US20010011479A1 - Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor - Google Patents
Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor Download PDFInfo
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- US20010011479A1 US20010011479A1 US09/812,087 US81208701A US2001011479A1 US 20010011479 A1 US20010011479 A1 US 20010011479A1 US 81208701 A US81208701 A US 81208701A US 2001011479 A1 US2001011479 A1 US 2001011479A1
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Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5607—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks
- G01C19/5628—Manufacturing; Trimming; Mounting; Housings
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
- G01P15/0922—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up of the bending or flexing mode type
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P2015/0805—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration
- G01P2015/0808—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate
- G01P2015/0811—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate for one single degree of freedom of movement of the mass
- G01P2015/0817—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining in-plane movement of the mass, i.e. movement of the mass in the plane of the substrate for one single degree of freedom of movement of the mass for pivoting movement of the mass, e.g. in-plane pendulum
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/42—Piezoelectric device making
Definitions
- the present invention relates to a vibration gyro sensor.
- the present invention relates to a vibration gyro sensor (scope) for detecting the angular velocity of rotation by utilizing the Coriolis force generated when a vibrator is rotated while making vibration, and a method for producing the vibration gyro sensor.
- the present invention also relates to a combined sensor including the vibration gyro sensor.
- the gyro sensor which is a sensor for detecting the angular velocity of rotation, has been hitherto used, for example, for inertial navigation systems of aircraft and shipping. Recently, the gyro sensor is used for vehicle-carried navigation systems and for attitude control systems of automatically guided robot vehicles. Further, the gyro sensor is also used, for example, for picture blurring-preventive systems of VTR cameras. In such circumstances, a compact type gyro sensor is required, which is appropriately used in various fields as described above. Accordingly, the vibration gyro sensor attracts attention.
- the vibration gyro sensor (scope) of this type has a basic structure comprising a driving piezoelectric element and a detecting piezoelectric element which adhere to a vibrator formed of a constant resilience metal represented by the elinvar alloy.
- a driving piezoelectric element and a detecting piezoelectric element which adhere to a vibrator formed of a constant resilience metal represented by the elinvar alloy.
- the Coriolis force acts in the y axis direction to the vibrator.
- the bending vibration in the y axis direction caused in the vibrator by the Coriolis force is detected as a voltage by the aid of the detecting piezoelectric element.
- the angular velocity is determined on the basis of the detected voltage.
- the conventional vibration gyro sensor as described above, the amount of displacement of the vibrator, which is based on the vibration induced by the driving piezoelectric element, is small. Therefore, the voltage (electromotive force), which is detected by the detecting piezoelectric element, is small. As a result, the conventional vibration gyro sensor involves a problem that the sensitivity is low.
- the driving piezoelectric element and the detecting piezoelectric element are glued and fixed to the vibrator by using an adhesive. Therefore, the adhesive intervenes between the vibrator and the piezoelectric elements. As a result, the stress is absorbed by the adhesive. Due to this fact, together with other factors, if any, a problem arises in that the detection sensitivity is lowered.
- the vibrator comprises a member which is composed of a sound chip or a tuning fork formed of an elinvar alloy
- a problem arises in that the characteristics of the vibrator tend to be affected by an ambient magnetic field, because the elinvar alloy is a ferromagnetic material.
- the shape or the material of the vibrator as described above there is an implicit problem that it is difficult to perform processing or machining when the resonance frequency of the vibrator is adjusted.
- the present invention provides a vibration gyro sensor which is constructed as a whole by an integrated fired product made of ceramics without using any magnetic material. Therefore, the vibration gyro sensor according to the present invention scarcely affected by any ambient magnetic field. Further, the vibration gyro sensor includes first plate-shaped sections and second plate-shaped sections which are thin-walled respectively and which are provided as easily bendable sections in driving and detecting directions for making displacement of vibrators respectively. Therefore, large displacement is obtained in any of the detecting and driving directions, thus giving a large electromotive force (voltage) generated depending on the displacement detected by piezoelectric/electrostrictive elements, and making it possible to effectively increase the detection sensitivity. Especially, the detecting section has a structure to which the stress is concentrated. Therefore, a large output is obtained.
- the vibration gyro sensor according to the present invention includes the detecting piezoelectric/electrostrictive elements which are formed in an integrated manner in accordance with a film formation method on the first plate-shaped sections for giving the detecting sections constructed by the integrated fired product made of ceramics.
- the piezoelectric/electrostrictive elements directly contact with the first plate-shaped sections without any intervening adhesive layer. Therefore, any absorption of stress, which would be otherwise caused due to the presence of such an adhesive layer, is effectively avoided.
- the displacement (bending vibration) of the vibrators which is caused by the Coriolis force induced when the vibrators are rotated, can be effectively detected by the piezoelectric/electrostrictive elements, making it possible to advantageously contribute to the improvement in sensitivity.
- the electrode area of the piezoelectric/electrostrictive element provided on the detecting section can be easily changed by using an appropriate removing means such as a laser. Therefore, the vibration gyro sensor also has such a feature that its electric characteristics are easily adjusted.
- the vibrator is provided with a thin-walled excisable section extending from a forward end of the vibrator, and a resonance frequency of the vibrator is adjusted in accordance with an amount of excision of the excisable section.
- the thin-walled excisable section which is provided at the end of the vibrator, is an easily processible or machinable portion.
- the resonance frequency of the vibrator can be easily adjusted to have a desired value by providing such an excisable section for trimming beforehand, and excising the excisable section by means of an appropriate excising means such as laser machining and ultrasonic machining.
- the vibration gyro sensor may be constructed such that the driving means comprises a third plate-shaped section which is more thin-walled than the vibrator and which is composed of the integrated fired product of ceramics together with the vibrator, and a driving piezoelectric/electrostrictive element formed in an integrated manner on the third plate-shaped section in accordance with the film formation method.
- a support bar is arranged at a position which is located between the two vibrators and which is separated from the vibrators, and the support bar is supported in an integrated manner by the support base together with the two vibrators.
- the support base is constructed by an attachment frame which is disposed outside the vibrator and separated therefrom by a predetermined distance so that the vibrator is surrounded thereby. Provision of the attachment frame makes it, possible to tightly fix the vibration gyro sensor, exhibiting a feature that a place for installing the vibration gyro sensor can be selected with a large degree of freedom.
- the driving means may be provided in an integrated manner between the two vibrators.
- the driving means may be provided in an integrated manner between the second plate-shaped sections.
- the driving means may be provided in an integrated manner between the support bar and the vibrators respectively, or the driving means may be provided in an integrated manner between the support bar and the second plate-shaped sections respectively.
- the driving means may be provided in an integrated manner between the attachment frame and the vibrators respectively, or the driving means may be provided in an integrated manner between the attachment frame and the second plate-shaped sections respectively.
- a second type of the vibration gyro sensor wherein a second plate-shaped section and a third plate-shaped section are provided in an integrated manner at opposing regions on a frame for supporting two vibrators, and a driving piezoelectric/electrostrictive element is formed in an integrated manner on the third plate-shaped section so that the two vibrators may be vibrated in an excited manner in accordance with deformation vibration of the frame effected by the driving piezoelectric/electrostrictive element.
- the vibration gyro sensor which makes the deformation vibration of the frame as described above, advantageously adopts a structure in which an attachment section for fixing the frame is formed in an integrated manner on an outer surface of a region of the frame for forming the second plate-shaped section, in order to facilitate fixation of the frame.
- the attachment section includes, in an integrated manner, an attachment frame which is positioned outside the frame and separated therefrom by a predetermined distance so that the frame is surrounded thereby.
- Such an attachment frame realizes tight fixation of the vibration gyro sensor.
- a third type of the vibration gyro sensor according to the present invention which is different from the vibration gyro sensors of the foregoing two types. Namely, support base portions for supporting two vibrators respectively are individually subjected to deformation vibration respectively by the aid of driving piezoelectric/electrostrictive elements provided on third plate-shaped sections for making connection to an attachment frame disposed outside. Accordingly, the two vibrators, which are supported by the respective support base portions, are individually vibrated in an identical plane respectively.
- the vibration gyro sensor of the third type is also advantageously constructed such that each of the vibrators has a thin-walled excisable section extending from a forward end thereof, in the same manner as the vibration gyro sensor of the second type.
- the resonance frequency of the vibrator is adjusted in accordance with the amount of excision of the excisable section. Accordingly, trimming can be easily performed by means of an excising means such as laser machining and ultrasonic machining. Thus it is possible to easily adjust the resonance frequency.
- a fourth type of the vibration gyro sensor according to the present invention.
- the force (Coriolis force) directed in the certain direction is generated in an alternating manner in the vibrators in accordance with the vibration.
- a force acts on the detecting sections in the certain direction, and the detecting sections are vibrated by the force.
- rotational vibration is generated around the axis of rotation at portions comprising the vibrators and the support base.
- the generated vibration is detected as an electromotive force (voltage) by the piezoelectric/electrostrictive elements of the detecting sections.
- all of the vibrators, the support base, and the detecting sections are. constructed by an integrated fired product made of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. As a result, the characteristics of the sensor are not affected by any ambient magnetic field.
- the detecting section is constructed by the first plate-shaped section which is more thin-walled than the vibrator in its direction of height, and thus it has the structure having low rigidity. Therefore, large strain or distortion is obtained in the detecting section when the vibration is generated around the axis of rotation by the angular velocity, and thus the detection sensitivity of the piezoelectric/electrostrictive element is greatly improved.
- the vibration gyro sensor according to the present invention functions such that the vibration is generated in the detecting section only when the angular velocity is applied. Therefore, the output (null voltage), which is obtained from the piezoelectric/electrostrictive element in a state in which no angular velocity is applied, is extremely small. Thus the detection sensitivity is greatly improved. Moreover, the probability of occurrence of fatigue fracture at the detecting section due to vibration is lowered, and it is possible to contemplate a long service life of the sensor.
- the vibration gyro sensor according to the present invention has the structure not for measuring the angular velocity around the major axis of the vibrator, but for measuring the angular velocity around the axis perpendicular to the plane which includes the certain direction and the extending direction of the support base. Therefore, the vibrators, the support base, and the frame can be made thin in their direction of height. Thus it is possible to facilitate realization of a compact size and a light weight of the sensor.
- each of the detecting sections is constructed by a ring member formed between the support base and the frame, and the first plate-shaped section provided in a bridged manner in the ring member in parallel to the extending direction of the support base.
- the force acts in the certain direction on the detecting section.
- the action of the force allows the ring member to make vibration while giving an elliptic configuration having its major or minor axis directed in the certain direction.
- the vibration of the ring member along the certain direction is detected as an electromotive force (voltage) by the piezoelectric/electrostrictive element.
- the vibration gyro sensor it is preferable for the vibration gyro sensor according to the present invention that at least two of the vibrators are supported by the support base in parallel to one another, and a driving means for vibrating the respective vibrators in an excited manner in mutually opposite directions is disposed between the two vibrators.
- the at least two vibrators make excited vibration in the mutually opposite directions, namely in directions to make mutual separation and approach in one plane (in the plane which includes the certain direction and the extending direction of the support base).
- the driving means includes, for example, a third plate-shaped section which is more thin-walled in its direction of height than the vibrator and which is constructed by the integrated fired product of ceramics together with the vibrator, and a driving piezoelectric/electrostrictive element formed on the third plate-shaped section.
- the driving means is provided in an integrated manner between the two vibrators.
- the driving means is arranged on a line for connecting respective centers of gravity of the both vibrators. This arrangement is advantageous to improve the sensitivity of the detecting section, since the at least two vibrators can make mutual approach and separation efficiently.
- the driving means may be provided in an integrated manner between the respective vibrators and the support base.
- the vibration gyro sensor constructed as described above further comprises a reference means for performing feedback control so that the vibration of the driving means is constant.
- the reference means may comprise a fourth plate-shaped section which is more thin-walled in its direction of height than the vibrator and which is constructed by the integrated fired product made of ceramics together with the vibrator, and a reference piezoelectric/electrostrictive element formed on the fourth plate-shaped section.
- the reference means may be provided in an integrated manner between the respective vibrators.
- the reference means may be provided in an integrated manner between the respective vibrators and the support base.
- the vibration gyro sensor constructed as described above further comprises vibration-applying sections provided in an integrated manner between the respective vibrators and the support base.
- the vibration-applying section may comprise a fifth plate-shaped section arranged between the vibrator and the support base and extending in parallel to a longitudinal direction of the support base, a sixth plate-shaped sections for connecting the support base to the fifth plate-shaped section, and a seventh plate-shaped section for connecting the vibrator to the fifth plate-shaped section.
- the driving means may be provided in an integrated manner between the respective vibration-applying sections.
- the driving means may be provided in an integrated manner between each of the vibration-applying sections and the support base.
- the vibration gyro sensor constructed as described above further comprises thin-walled first projections for adjusting a resonance frequency for driving, provided at free ends of the vibrators, and thin-walled second projections for adjusting a resonance frequency for detection, provided at both ends of the support base in its longitudinal direction, wherein the first and second projections are constructed by the integrated fired product made of ceramics together with the vibrators and the support base.
- the resonance frequency for driving can be adjusted by applying a trimming treatment (excising treatment) to the first projection
- the resonance frequency for detection can be adjusted by applying a trimming treatment (excising treatment) to the second projection.
- the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving.
- the resonance frequency for driving it is preferable that the resonance frequency for driving is firstly adjusted, and then the resonance frequency for detection is adjusted.
- the first and second projections may be constructed to be plate-shaped and thin-walled in a direction of height with respect to the vibrators.
- the first and second projections may be constructed to be plate-shaped and thin-walled in the extending direction of the support base with respect to the vibrators.
- the former construction is advantageous in that the trimming treatment can be easily performed by means of, for example, laser beam scanning over the upper surface.
- regions to be subjected to the trimming treatment are disposed over entire surfaces perpendicular to the direction of vibration of the vibrators, and hence an extremely excellent mass balance is obtained.
- the trimming treatment is performed, for example, by applying percussion such as ultrasonic waves after laser radiation so that unnecessary portions are excised.
- the vibration gyro sensor constructed as described above that the third plate-shaped section of the driving means is also used as an adjustment objective for a resonance frequency for driving, and the first plate-shaped section of the detecting section is also used as an adjustment objective for a resonance frequency for detection.
- the resonance frequency for driving is adjusted by trimming-treating, in the widthwise direction, the third plate-shaped section of the driving means, and the resonance frequency for detection is adjusted by trimming-treating, in the widthwise direction, the first plate-shaped section of the detecting section.
- this embodiment lies in the method in which the resonance frequencies for driving and detection are adjusted by changing spring constants of the first and third plate-shaped sections, rather than that the resonance frequencies for driving and detection are adjusted by changing masses of the vibrator and the support base.
- the resonance frequency can be easily adjusted. Unlike the method in which the resonance frequency is adjusted by changing the mass, the resonance frequency for driving and the resonance frequency for detection can be adjusted completely independently.
- a fifth type of the vibration gyro sensor wherein vibrators are constructed by wide and lengthy first plate-shaped sections respectively. Accordingly, the mass and the moment of the vibrator are increased. As a result, the velocity ( ⁇ amplitude) brought about by the driving vibration is increased. Therefore, it is possible to further improve the sensitivity.
- the detecting piezoelectric/electrostrictive element is formed in an integrated manner on an approximately entire surface of the first plate-shaped section. This embodiment is advantageous in the case of the current-detecting system, because it is possible to accumulate a large amount of electric charge.
- the vibration gyro sensor constructed as described above that the first plate-shaped section has, on its back surface, a plurality of recesses, and the detecting piezoelectric/electrostrictive elements as defined above are formed in an array of islands at positions on a front surface of the first plate-shaped section corresponding to the plurality of recesses.
- the strength is decreased at the portions of the first plate-shaped section at which the recesses are formed. Therefore, when the first plate-shaped section is deformed by the Coriolis force, large strain is generated at the portions at which the recesses are formed as compared with other portions at which no recess is formed. Accordingly, when the detecting piezoelectric/electrostrictive elements are formed on the portions corresponding to the recesses, a large detection output can be obtained, and the sensitivity can be further improved.
- the vibration gyro sensor constructed as described above that a thick-walled block section is provided in an integrated manner between the first plate-shaped section and the second plate-shaped section.
- a thick-walled block section is provided in an integrated manner between the first plate-shaped section and the second plate-shaped section.
- the support base may be constructed by a frame which is positioned outside the vibrators and separated by predetermined distances so that the vibrators are surrounded thereby.
- the support base has the form of frame, it is possible to obtain a large degree of freedom for attachment, and the rigidity is excellent. Therefore, this embodiment is preferred from a practical viewpoint.
- the driving means may be provided in an integrated manner between the respective second plate-shaped sections.
- the driving means may be provided in an integrated manner between the respective block sections.
- the driving means may be provided in an integrated manner between the block section and the frame.
- the vibration gyro sensor constructed as described above further comprises a reference means for performing feedback control so that the vibration of the driving means is constant.
- the reference means may be provided in an integrated manner between the respective second plate-shaped sections.
- the driving means may be provided in an integrated manner on one plate-shaped section of the respective second plate-shaped sections, and the reference means may be provided on the other plate-shaped section.
- an attachment section for fixing the support base is provided in an integrated manner on a surface opposite to a surface of the support base on which the second plate-shaped sections are formed
- a fifth plate-shaped section which is thin-walled in a widthwise direction of the support base, is provided in an integrated manner between the support base and the attachment section
- a tuning fork is constructed by at least the support base and the vibrators.
- the fifth plate-shaped section functions as a support rod for supporting the tuning fork. Therefore, it is easy to discriminate necessary modes for the vibration gyro sensor from unnecessary modes, and it is possible to improve the detection accuracy.
- the attachment section is constructed by an attachment frame which is positioned outside the tuning fork and separated by predetermined distances therefrom so that the tuning fork is surrounded thereby.
- this embodiment it is possible to improve the detection accuracy. Further, this embodiment is preferred, for example, from viewpoints of the degree of freedom for attachment and rigidity, because the attachment section is provided as the attachment frame.
- the present invention makes it possible to advantageously construct and realize a combined sensor by using those provided with the attachment frame, of the vibration gyro sensors described above, wherein a second attachment frame integrated with the attachment frame is provided adjacent to the attachment frame, and another sensor having a function different from that of the vibration gyro sensor is supported in an integrated manner in the second attachment frame.
- the conventional vibration gyro sensor merely realizes an element having only one function.
- an additional sensor having another function is provided by utilizing the attachment frame as described above, it is possible to easily provide a combined sensor or an integrated sensor which not only functions as the vibration gyro sensor, but also simultaneously realizes another function.
- the present invention lies in a method for producing a vibration gyro sensor, comprising the steps of stacking and integrating at least a substrate layer and a thin plate layer composed of green sheets, followed by firing to produce a fired product including, in an integrated manner, at least one or more vibrators each having a major axis extending in a certain direction, a support base extending in a direction perpendicular to the certain direction, for supporting the vibrator at one end, a frame having its frame surface parallel to a plane which includes the certain direction and the extending direction of the support base, for surrounding the vibrator and the support base, and at least one or more detecting sections attached between the support base and the frame; forming at least one or more piezoelectric/electrostrictive elements on at least the detecting sections in accordance with a film formation method; adjusting a resonance frequency for driving by applying a trimming treatment to a part of the vibrator; and adjusting a resonance frequency for detection by applying a trimming treatment to a part
- the vibration gyro sensor having the structure in which the support base and the vibrators are surrounded by the frame, and the support base is connected to the frame via the detecting sections.
- the resonance frequencies for driving and detection can be easily adjusted by trimming-treating a part of the vibrators and a part of the support base respectively. Therefore, this method is advantageous to reduce the number of production steps.
- a vibration gyro sensor comprising at least two of the vibrators supported in parallel to one another by the support base, and a driving means provided between the two vibrators for vibrating the respective vibrators in an excited manner in mutually opposite directions
- the driving means includes a third plate-shaped section which is more thin-walled in its direction of height than the vibrators and which is composed of the integrated fired product made of ceramics together with the vibrators, and a driving piezoelectric/electrostrictive element formed on the third plate-shaped section.
- the adjustment for the resonance frequency for driving is performed by applying a trimming treatment to a thin-walled first projection protruding in an integrated manner from a free end of the vibrator
- the adjustment for the resonance frequency for detection is performed by applying a trimming treatment to thin-walled second projections protruding in an integrated manner from both ends of the support base in its longitudinal direction.
- the resonance frequency for driving can be adjusted by applying the trimming treatment (excising treatment) to the first projection
- the resonance frequency for detection can be adjusted by applying the trimming treatment (excising treatment) to the second projection.
- the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving.
- the adjustment for the resonance frequency for driving is performed by applying a trimming treatment to the third plate-shaped section in its widthwise direction
- the adjustment for the resonance frequency for detection is performed by applying a trimming treatment to the first plate-shaped section of the detecting section in its widthwise direction.
- This embodiment lies in the method in which the resonance frequencies for driving and detection are adjusted by changing spring constants of the first and third plate-shaped sections, rather than that the resonance frequencies for driving and detection are adjusted by changing masses of the vibrators and the support base. Therefore, it is unnecessary to form the first and second projections at the free ends of the vibrators and at the both ends of the support base in the longitudinal direction respectively. Accordingly, the production steps can be simplified. Further, since the regions to be subjected to the trimming treatment are thin-walled, the resonance frequency can be easily adjusted. Unlike the method in which the resonance frequency is adjusted by changing the mass, the resonance frequency for driving and the resonance frequency for detection can be adjusted completely independently.
- the resonance frequency for detection is adjusted after the resonance frequency for driving is adjusted.
- FIG. 1 schematically shows a perspective view illustrating a first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 2 schematically shows an exploded perspective view illustrating the vibration gyro sensor shown in FIG. 1.
- FIG. 3 schematically shows a partial perspective view illustrating, in a magnified manner, a portion of a first plate-shaped section of the vibration gyro sensor shown in FIG. 1.
- FIG. 4 schematically shows a perspective view illustrating a second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 5 schematically shows a perspective view illustrating a third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 6 schematically shows a perspective view illustrating a fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 7 schematically shows a perspective view illustrating a fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 8 schematically shows a perspective view illustrating a sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 9 schematically shows a perspective view illustrating a seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 10 schematically shows a perspective view illustrating an eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 11 schematically shows a perspective view illustrating a ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 12 schematically shows a perspective view illustrating a tenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 13 schematically shows a perspective view illustrating an eleventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 14 schematically shows a perspective view illustrating a twelfth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 15 schematically shows a perspective view illustrating a preferred embodiment of the combined sensor according to the present invention.
- FIG. 16 schematically shows a perspective view illustrating another preferred embodiment of the combined sensor according to the present invention.
- FIG. 17 schematically shows illustrative production steps for the vibration gyro sensor according to the first embodiment shown in FIG. 1.
- FIG. 18 schematically shows illustrative production steps for the vibration gyro sensor according to the fifth embodiment shown in FIG. 7.
- FIG. 19 shows a perspective view illustrating a magnified electrode structure of the type based on the use of the longitudinal effect of the electric field-induced strain.
- FIG. 20 schematically shows a perspective view illustrating a thirteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 21 schematically shows a perspective view illustrating a fourteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 22 schematically shows a perspective view illustrating a fifteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 23 schematically shows a perspective view illustrating a sixteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 24 schematically shows a perspective view illustrating an exemplary structure of projections used to adjust the resonance frequency in the vibration gyro sensor according to the fifteenth embodiment.
- FIG. 25 schematically shows a perspective view illustrating another exemplary structure of projections used to adjust the resonance frequency in the vibration gyro sensor according to the fifteenth embodiment.
- FIG. 26 schematically shows a perspective view illustrating a seventeenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 27 schematically shows a perspective view illustrating an exemplary structure used to adjust the resonance frequencies for driving and detection by changing spring constants of the driving and detecting sections in the vibration gyro sensor according to the seventeenth embodiment.
- FIG. 28 schematically shows a perspective view illustrating an eighteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 29 schematically shows a perspective view illustrating a nineteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 30 schematically shows a perspective view illustrating a twentieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 31 schematically shows a perspective view illustrating a twenty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 32 schematically shows a perspective view illustrating a twenty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 33 schematically shows a perspective view illustrating a twenty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 34 schematically shows a perspective view illustrating a twenty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 35 schematically shows a perspective view illustrating a twenty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 36 schematically shows a perspective view illustrating a twenty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 37 schematically shows a perspective view illustrating an exemplary wiring formation pattern led from pairs of electrodes of piezoelectric/electrostrictive elements in the vibration gyro sensor according to the seventeenth embodiment.
- FIG. 38 schematically shows a perspective view illustrating a twenty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 39 schematically shows a perspective view illustrating a twenty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 40 schematically shows a perspective view illustrating a twenty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 41 schematically shows a perspective view illustrating a thirtieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 42 schematically shows a perspective view illustrating a thirty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 43 shows a cross-sectional view taken along a line A-A shown in FIG. 42.
- FIG. 44 schematically shows a perspective view illustrating a thirty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 45 schematically shows a perspective view illustrating a thirty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 46 schematically shows a perspective view illustrating a thirty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 47 schematically shows a perspective view illustrating a thirty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 48 shows a cross-sectional view taken along a line B-B shown in FIG. 47.
- FIG. 49 schematically shows a perspective view illustrating a thirty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 50 schematically shows a perspective view illustrating a thirty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 51 schematically shows a perspective view illustrating a thirty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 52 schematically shows a perspective view illustrating a thirty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 53 shows characteristic curves illustrating the change in resonance angular frequency ratio depending on the length of the support rod for supporting the tuning fork.
- FIG. 54 schematically shows a perspective view illustrating a fortieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 55 schematically shows a perspective view illustrating a forty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 56 schematically shows a perspective view illustrating a forty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 57 schematically shows a perspective view illustrating a forty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 58 schematically shows a perspective view illustrating a forty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 59 schematically shows a perspective view illustrating a forty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 60 schematically shows a perspective view illustrating a forty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 61 schematically shows a perspective view illustrating a forty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 62 shows a magnified structure of a portion at which lead wires are led in the vibration gyro sensor according to the forty-seventh embodiment.
- FIG. 63 schematically shows a perspective view illustrating a forty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 64 shows a magnified structure of a portion at which lead wires are led in the vibration gyro sensor according to the forty-eighth embodiment.
- FIG. 65 schematically shows a perspective view illustrating a forty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 66 schematically shows a perspective view illustrating a fiftieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 67 schematically shows a perspective view illustrating a fifty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 68 schematically shows a perspective view illustrating a fifty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 69 schematically shows a perspective view illustrating a fifty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 70A shows a cross-sectional view taken along a line C-C shown in FIG. 69.
- FIG. 70B shows a cross-sectional view taken along a line D-D shown in FIG. 69.
- FIG. 70C shows a cross-sectional view taken along a line E-E shown in FIG. 69.
- FIG. 71 schematically shows a perspective view illustrating a fifty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 72 schematically shows a perspective view illustrating a fifty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 73 schematically shows an exploded perspective view illustrating another structure of the vibration gyro sensor according to the first embodiment shown in FIG. 1.
- FIG. 74 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-third embodiment shown in FIG. 45.
- FIG. 75 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-fourth embodiment shown in FIG. 46.
- FIG. 76 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47.
- FIG. 1 an embodiment (first embodiment) of the vibration gyro sensor according to the present invention is shown in FIG. 1.
- two angular rod-shaped vibrators 2 , 2 composed of a fired product of ceramics, each of which has a rectangular cross section and extends longitudinally, are arranged in parallel to one another and separated from each other by a predetermined spacing distance.
- the two vibrators 2 , 2 are connected in an integrated manner at their proximal ends to a rectangular angular rod-shaped support base 4 composed of a fired product of ceramics respectively so that the vibrators 2 , 2 are supported by the support base 4 .
- Each of the vibrators 2 , 2 includes a first plate-shaped section 6 to serve as a detecting section which is formed in an integrated manner with its thin-walled region disposed fairly close to the support base 4 and with its principal surface extending in a direction of arrangement of the vibrators 2 , 2 .
- Each of the vibrators 2 , 2 has its proximal end region to serve as a thin-walled second plate-shaped section 8 which has its width thinner than a width of the vibrator 2 and has its principal surfaces extending in a direction perpendicular to the first plate-shaped section 6 .
- the vibrators 2 , 2 are connected in an integrated manner to the support base 4 via the second plate-shaped sections 8 , 8 .
- the two vibrators 2 , 2 are connected to one another in an integrated manner at their regions located between the first plate-shaped sections 6 , 6 and the second plate-shaped sections 8 , 8 respectively via a third plate-shaped section 10 which is more thin-walled than the vibrators 2 , 2 and has its principal surface parallel to the principal surfaces of the first plate-shaped sections 6 , 6 .
- the two vibrators 2 , 2 , the support base 4 , the first plate-shaped sections 6 , 6 , the second plate-shaped sections 8 , 8 , and the third plate-shaped section 10 are constructed by an integrated fired product made of ceramics, thus giving an integrated structure.
- the vibration gyro sensor which is constructed by the integrated fired product of ceramics as described above, can be grasped as an integrated stacked structure comprising a thin plate layer 22 , a substrate layer 24 , and a spacer layer 26 .
- the first plate-shaped sections 6 , 6 and the third plate-shaped section 10 are given by the thin plate layer 22
- the vibrators 2 , 2 and the second plate-shaped sections 8 , 8 are given by stacking and integrating the thin plate layer 22 and the substrate layer 24
- the support base 4 is given by stacking and integrating the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 .
- Detecting piezoelectric/electrostrictive elements 12 , 12 are formed in an integrated manner on the thin-walled first plate-shaped sections 6 , 6 formed on the respective vibrators 2 , 2 , in accordance with a known film formation method respectively. As shown in FIG. 3 with magnification, the detecting piezoelectric/electrostrictive element 12 is directly formed on the first plate-shaped section 6 in a form in which a thin film-shaped lower electrode 12 a, a piezoelectric/electrostrictive layer 12 b, and an upper electrode 12 c are stacked and integrated with each other.
- the detecting piezoelectric/electrostrictive elements 12 , 12 detect vibration or displacement induced in the vibrators 2 , 2 in a direction perpendicular to the arrangement plane of the two vibrators 2 , 2 .
- a driving piezoelectric/electrostrictive element 14 to serve as a driving means is formed in an integrated manner on the third plate-shaped section 10 , as constructed in the same manner as the detecting piezoelectric/electrostrictive elements 12 , 12 , in accordance with the known film formation method as well.
- the two vibrators 2 , 2 are subjected to bending vibration in their arrangement plane in mutually opposite directions, i.e., in directions to make mutual approach and separation in the x axis direction.
- Thin-walled excisable sections 16 , 16 are provided at forward ends of the respective vibrators 2 , 2 on a side opposite to the connecting section with respect to the support base 4 , and the excisable sections 16 , 16 extend in an integrated manner therefrom.
- the excisable sections 16 , 16 may be easily trimmed by means of, for example, laser machining and ultrasonic machining.
- the upper surface of the support base 4 is flush with the upper surfaces of the vibrators 2 , 2 , and the support base 4 has a shape with its thickness which is thicker than that of the vibrators 2 , 2 . Accordingly, the lower surface of the support base 4 is located at a position lower than the vibrators 2 , 2 .
- the support base 4 includes, in an integrated manner, a spacer section 18 corresponding to the spacer layer 26 shown in FIG. 2.
- the support base 4 is thicker than the vibrators 2 , 2 by a thickness of the spacer section 18 .
- the vibration gyro sensor is attached at the portion of the support base 4 to a flat attachment plane in the vertical direction by the aid of bolts 20 , the vibrators 2 , 2 do not suffer interference from the attachment plane, owing to the presence of the spacer section 18 as described above.
- the vibration gyro sensor having the structure as described above is operated as follows. Namely, the third plate-shaped section 10 undergoes deformation by operating the driving piezoelectric/electrostrictive element 14 . Accordingly, the two vibrators 2 , 2 are subjected to excited vibration (bending vibration) in mutually opposite directions in the x axis direction, in other words, in directions to make mutual approach and separation in the rectangular coordinate system composed of the x, y, z axes shown in FIG. 1.
- the Coriolis force acts in the y axis direction on the vibrators 2 , 2 on the basis of the angular velocity about the z axis. Accordingly, the Coriolis force allows the vibrators 2 , 2 to make vibration in mutually opposite directions in the y axis direction.
- the bending vibration of the vibrators 2 , 2 in the y axis direction as described above is detected as an electromotive force (voltage) by the aid of the detecting piezoelectric/electrostrictive elements 12 , 12 .
- the vibration gyro sensor is constructed as a whole by the integrated fired product made of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. For this reason, no problem occurs, i.e., the characteristics of the sensor are not affected by any ambient magnetic field.
- the detecting piezoelectric/electrostrictive elements 12 , 12 and the driving piezoelectric/electrostrictive element 14 are directly formed in the integrated manner on the first plate-shaped sections 6 , 6 and the third plate-shaped section 10 in accordance with the film formation method. No adhesive layer exists at all between the elements and the plate-shaped sections. Therefore, the problem of decrease in sensitivity, which would be otherwise caused by the absorption of stress brought about by such an adhesive layer, is effectively dissolved.
- the deformation is advantageously caused by the operation of the driving piezoelectric/electrostrictive element 14 , owing to the fact that the driving piezoelectric/electrostrictive element 14 to serve as an actuator is formed in the integrated manner on the thin-walled third plate-shaped section 10 .
- the respective vibrators 2 , 2 are connected in the integrated manner to the support base 4 via the thin-walled second plate-shaped sections 8 , 8 , and the second plate-shaped sections 8 , 8 are provided as the thin plate sections having their principal surfaces which extend in the direction (y axis direction) perpendicular to the direction (x axis direction) of vibration of the vibrators 2 , 2 .
- the rigidity in the direction of vibration is effectively decreased, making it possible to cause vibration easily.
- large displacement is obtained by the driving operation effected on the vibrators 2 , 2 by the driving piezoelectric/electrostrictive element 14 .
- the ratio of the width (thickness) to the height of the second plate-shaped section 8 is made small, it is possible to suppress vibration in the vertical direction (y axis direction) which serves as a factor to decrease the sensitivity.
- the first plate-shaped section 6 on which the detecting piezoelectric/electrostrictive element 12 is formed in the integrated manner, is formed to be more thin-walled than the vibrator 2 so that its principal surface extends in the direction of vibration (x axis direction) of the vibrator 2 , in other words, the principal surface is located within the vibration plane of the vibrator 2 . Accordingly, large displacement is obtained when bending vibration is generated in the y axis direction which is the direction perpendicular to the x axis direction.
- the easily bendable regions exist in any of the direction of detecting vibration (direction of the y axis) and the direction of driving vibration (direction of the x axis), and hence large displacement is obtained in any of the driving and detecting operations. Accordingly, the sensitivity of the vibration gyro sensor is extremely enhanced.
- the first plate-shaped section 6 on which the detecting piezoelectric/electrostrictive element 12 is formed for giving the detecting section, is thin-walled to provide the structure so that the stress is concentrated. Thus a large output is obtained.
- the thin-walled excisable section 16 which extends in the integrated manner from the forward end of the vibrator 2 . Therefore, the excisable section 16 is easily subjected to the trimming processing or machining such as the laser machining and the ultrasonic machining, making it easy to adjust the resonance frequency of the vibrator 2 .
- the electrode area of the detecting piezoelectric/electrostrictive element 12 and the driving piezoelectric/electrostrictive element 14 can be easily changed by using a laser or the like, making it possible to easily adjust the electric characteristics thereof.
- the vibration gyro sensor according to this embodiment has the structure in which the third plate-shaped section 10 , on which the driving piezoelectric/electrostrictive element 14 is provided, is formed in the integrated manner so that the two vibrators 2 , 2 are bridged at their proximal ends. Accordingly, the vibration gyro sensor is also advantageous in that it is possible to effectively suppress the restriction of vibration of the vibrators 2 , 2 by the third plate-shaped section 10 .
- the vibration gyro sensor according to the present invention may be embodied by various structures other than the structure described above, within a range without deviating from the gist or essential characteristics of the present invention. Representative embodiments are shown in FIG. 4 and followings. The following embodiments will be explained only for their characteristic portions. The same or equivalent components or parts as those described in the first embodiment are designated by the same reference numerals, detailed explanation of which will be omitted.
- a second embodiment shown in FIG. 4 has the following feature. Namely, vibrators 2 , 2 are connected in an integrated manner to forward ends of U-shaped portions of a U-shaped support base 4 via thin-walled first plate-shaped sections 6 , 6 . Second plate-shaped sections 8 , 8 are positioned at forward ends of the vibrators 2 , 2 . A thin-walled third plate-shaped section 10 for connecting the two vibrators 2 , 2 in an integrated manner is formed in an integrated manner at positions located nearer to the forward ends as compared with the second plate-shaped sections 8 , 8 .
- the third plate-shaped section 10 is provided at the position nearer to the forward ends of the vibrators 2 , 2 as compared with the first embodiment. Therefore, although a problem arises in that the vibration of the vibrators 2 , 2 tends to be restricted by the third plate-shaped section 10 , it is still possible to obtain displacement which is larger than that obtained by the conventional vibration gyro sensor.
- the vibration gyro sensor is constructed by an integrated fired product made of ceramics having a structure in which an angular bar-shaped support bar 28 having a rectangular cross section is arranged between two vibrators 2 , 2 in parallel to the vibrators 2 , 2 .
- the support bar 28 is disposed between the two vibrators 2 , 2 at a position separated from the vibrators 2 , 2 by a predetermined distance, and it is integrally connected to and supported by a support base 4 .
- Thin-walled third plate-shaped sections 10 , 10 are formed in an integrated manner between the support bar 28 and the vibrators 2 , 2 disposed at the right and left thereof.
- Driving piezoelectric/electrostrictive elements 14 , 14 are formed on the third plate-shaped sections 10 , 10 respectively. The operation of the driving piezoelectric/electrostrictive elements 14 , 14 causes the right and left vibrators 2 , 2 to make excited vibration in mutually opposite directions respectively.
- FIGS. 7 and 8 show fifth and sixth embodiments having the following structure respectively. Namely, an integrated fired structure of ceramics is used in a state in which the support base 4 for supporting two vibrators 2 , 2 at their proximal ends is constructed by an attachment frame 30 having a rectangular configuration. The two vibrators 2 , 2 are accommodated in the attachment frame 30 , and predetermined gaps are formed between the vibrators 2 , 2 and the attachment frame 30 .
- Independent driving means are provided in an integrated manner between the two vibrators 2 , 2 and the attachment frame 30 which surrounds the two vibrators 2 , 2 respectively.
- actuators are provided in an integrated manner between the two vibrators 2 , 2 and the attachment frame 30 which surrounds the two vibrators 2 , 2 respectively.
- thin-walled third plate-shaped sections 10 , 10 are formed in an integrated manner between the two vibrators 2 , 2 and sides of the attachment frame 30 opposing thereto.
- Driving piezoelectric/electrostrictive elements 14 , 14 are formed on the third plate-shaped sections 10 , 10 respectively in accordance with the film formation method.
- the attachment frame 30 can be tightly fixed to a flat attachment plane via the spacer section 18 by the aid of bolts 20 or the like. Accordingly, the vibration gyro sensor is advantageous in that the degree of freedom is large concerning the place for installation.
- FIGS. 9 and 10 have similar structures as those described in the first and second embodiments concerning the support base 4 .
- the support base 4 is provided as an integrated fired structure made of ceramics in a form of an attachment frame 30 having a rectangular configuration so that the two vibrators 2 , 2 are surrounded thereby.
- each of the vibration gyro sensors according to the seventh and eighth embodiments includes a driving means 10 , 14 formed in an integrated manner between the two vibrators 2 , 2 arranged in the attachment frame 30 having the rectangular frame structure.
- the attachment frame 30 can be tightly fixed via the spacer section 18 in the same manner as described in the fifth and sixth embodiments.
- These embodiments are also advantageous in that the degree of freedom is large concerning the place for installation.
- FIG. 11 shows a ninth embodiment of the vibration gyro sensor according to the present invention.
- the vibration gyro sensor is constructed by an integrated fired product structure made of ceramics wherein a frame 32 having a rectangular configuration, which serves as a support base for supporting two vibrators 2 , 2 at their proximal ends, is provided so that the two vibrators 2 , 2 are surrounded thereby.
- a thin-walled second plate-shaped section 8 which is provided to lower the rigidity of the vibrators 2 , 2 in the direction of vibration and facilitate vibration, is formed in an integrated manner at a portion of the frame 32 located between support regions for the two vibrators 2 , 2 so that the second plate-shaped section 8 gives its principal surface extending in a direction perpendicular to the direction of vibration (arrangement plane for the vibrators 2 , 2 ).
- a third plate-shaped section 10 which is more thin-walled than the frame 32 , is formed at a portion of the frame 32 opposing to the region for forming the second plate-shaped section 8 so that the third plate-shaped section 10 has its principal surface parallel to the principal surfaces of the first plate-shaped sections 6 , 6 .
- a driving piezoelectric/electrostrictive element 14 is formed in an integrated manner on the third plate-shaped section 10 in accordance with the film formation method.
- the operation of the driving piezoelectric/electrostrictive element 14 causes deformation of the third plate-shaped section 10 which induces bending vibration in the frame 32 by using the region of the second plate-shaped section 8 as a center.
- the two vibrators 2 , 2 are vibrated in an excited manner.
- FIGS. 12 and 13 show tenth and eleventh embodiments respectively, each based on the use of an integrated fired product structure made of ceramics, as illustrative structures for facilitating fixation of the vibration gyro sensor shown in FIG. 11.
- the embodiment shown in FIG. 12 includes an attachment section 34 for fixing a frame 32 , which is provided in an integrated manner at an outer surface corresponding to a region for forming the second plate-shaped section 8 formed in the rectangular frame 32 .
- the attachment section 34 has a triangular configuration, and it is connected in an integrated manner to the outer surface of the second plate-shaped section 8 at an apex of the triangle.
- the connecting section, at which the attachment section 34 is connected to the second plate-shaped section 8 has a width (length in the lateral direction in FIG. 12) which is smaller than a width of the second plate-shaped section 8 (length in the lateral direction in FIG. 12) because of the following reason.
- the vibration gyro sensor is fixed such that the attachment section 34 is fixed via the spacer section 18 by the aid of bolts 20 or the like.
- FIG. 13 illustrates a modified embodiment of the attachment section 34 as described in the embodiment shown in FIG. 12.
- this embodiment has a structure including, in an integrated manner, an attachment frame 36 which is disposed outside the frame 32 and separated therefrom by predetermined distances so that the frame 32 for giving the vibration gyro sensor is surrounded.
- a tight fixing structure can be realized by fixing the attachment frame 36 having a rectangular frame configuration by using bolts 20 .
- FIG. 14 A twelfth embodiment of the vibration gyro sensor according to the present invention is shown in FIG. 14, based on the use of an integrated fired product structure made of ceramics.
- a support base 4 which is provided for supporting two vibrators 2 , 2 at their proximal ends, has an angular U-shaped configuration.
- a second plate-shaped section 8 is formed at a portion located between support regions of the support base 4 for the two vibrators 2 , 2 .
- An attachment section 34 for fixing the support base 4 is connected in an integrated manner to the outer surface of the second plate-shaped section 8 , in the same manner as the embodiment shown in FIG. 13.
- Third plate-shaped sections 10 , 10 which are more thin-walled than the attachment frame 36 and the support base 4 , are formed in an integrated manner with their principal surfaces parallel to principal surfaces of first plate-shaped sections 6 , 6 so that the third plate-shaped sections 10 , 10 bridge the attachment frame 36 and portions of the support base 4 located on both sides of the second plate-shaped section 8 respectively.
- Driving piezoelectric/electrostrictive elements 14 , 14 are formed in an integrated manner on the third plate-shaped sections 10 , 10 in accordance with the film formation method.
- the attachment frames 30 , 36 shown in FIGS. 7 to 10 and FIGS. 13 and 14 may be utilized to provide a second attachment frame which is adjacent to the attachment frame and integrated with the attachment frame, as an integrated fired product structure made of ceramics.
- Another sensor, which has a function different from that of the vibration gyro sensor, is supported in an integrated manner in the second attachment frame.
- FIG. 15 An illustrative embodiment of such a combined sensor is shown in FIG. 15.
- a second attachment frame 38 integrated with an attachment frame 36 is provided as an integrated fired product structure made of ceramics, the second attachment frame 38 being adjacent to the attachment frame 36 of the vibration gyro sensor as shown in FIG. 13.
- An acceleration sensor which has a function distinct from the vibration gyro sensor, is provided in an integrated manner in the second attachment frame 38 .
- an acceleration sensor section 40 for detecting the angular velocity around the z axis, which constructs the vibration gyro sensor is provided on the left side of the system.
- An acceleration sensor section 42 is formed in the second attachment frame 38 on the right side of the system.
- the acceleration sensor section 42 comprises a first sensor 44 A and a second sensor 44 B for detecting the acceleration in the y axis direction, and a third sensor 44 C and a fourth sensor 44 D for detecting the acceleration in the x axis direction.
- Each of the first and second sensors 44 A, 44 B comprises a vibrator 46 a, 46 b as an inertial mass, a thin plate-shaped detecting section 48 a, 48 b for connecting the vibrator 46 a, 46 b to the attachment frame 38 in an integrated manner, and a detecting piezoelectric/electrostrictive element 50 a, 50 b formed on the detecting section 48 a, 48 b in an integrated manner in accordance with the film formation method and having the same or equivalent structure as that of the detecting piezoelectric/electrostrictive element 14 described above. Therefore, when an acceleration in the y axis direction is inputted, the detecting sections 48 a, 48 b are deformed respectively.
- a predetermined electromotive force (voltage) is outputted from the detecting piezoelectric/electrostrictive elements 50 a, 50 b on the basis of the deformation.
- the first and second sensors 44 A, 44 B also detect the acceleration in the x axis direction. When they are operated as described above, the two sensors make deformation in mutually opposite directions, the displacement being different from the displacement in an identical direction brought about when the acceleration in the y axis direction is applied. Accordingly, it is possible to achieve signal separation.
- Each of the third and fourth sensors 44 C, 44 D also comprises a vibrator 46 c, 46 d as an inertial mass, a thin plate-shaped detecting section 48 c, 48 d for connecting the vibrator 46 c, 46 d to the attachment frame 38 in an integrated manner, a detecting piezoelectric/electrostrictive element 50 c, 50 d formed on the detecting section 48 c, 48 d in an integrated manner in accordance with the film formation method and having the same or equivalent structure as that of the detecting piezoelectric/electrostrictive element 12 described above, and a thin plate-shaped connecting section 46 c′, 46 d′ for connecting the vibrator 46 c, 46 d to the attachment frame 38 to support the vibrator 46 c, 46 d in a state in which the vibrator 46 c, 46 d is easily displaceable in the x axis direction.
- any of the vibration gyro sensors and the combined sensors according to the present invention is composed of the integrated fired product made of ceramics except for the piezoelectric/electrostrictive elements 12 , 14 and 50 a to 50 d. Specifically, they are produced as follows.
- the main sensor body which comprises, for example, the vibrators 2 , the support base 4 , the first to third plate-shaped sections 6 , 8 , 10 , and the spacer section 18 , is given by the integrated fired product made of ceramics.
- materials for forming the integrated fired product of ceramics for providing the main sensor body include any of ceramic materials composed of oxide and any of ceramic materials composed of those other than oxide, provided that the material is an insulative material or a dielectric material having large mechanical strength, which can be subjected to a heat treatment at about 1400° C.
- those preferably adopted include materials comprising a major component of at least any one of aluminum oxide, magnesium oxide, zirconium oxide, aluminum nitride, and silicon nitride, in order to obtain excellent operation characteristics, i.e., large displacement, large generated force, and quick response speed.
- ceramic materials comprising, as a major component or major components, aluminum oxide and/or zirconium oxide.
- those advantageously used include materials comprising a major component of zirconium oxide stabilized with at least one compound selected from the group consisting of yttrium oxide, ytterbium oxide, cerium oxide, calcium oxide, and magnesium oxide, because they exhibits features such as high toughness and high mechanical strength obtained even when the plate thickness is thin.
- the foregoing compound is preferably added in an amount of 1 mole % to 30 mole % in the case of yttrium oxide and ytterbium oxide, 6 mole % to 50 mole % in the case of cerium oxide, or 5 mole % to 40 mole % in the case of calcium oxide and magnesium oxide.
- yttrium oxide is desirably added in an amount of 1.5 mole % to 6 mole %, more preferably 2 mole % to 4 mole %.
- the integrated fired product of ceramics which constructs the main sensor body as described above, advantageously comprises the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 , if necessary. It is advantageous to contain silicon oxide (SiO, SiO 2 ) at least in the material to give the thin plate layer 22 .
- the content of silicon oxide is preferably not less than 0.5% by weight and not more than 5% by weight, and especially desirably not less than 1% by weight and not more than 3% by weight.
- the content of silicon oxide in the ratio as described above is effective to avoid any excessive reaction with the piezoelectric/electrostrictive material during the heat treatment for the piezoelectric/electrostrictive element 12 , 14 formed on the thin plate layer 22 so that good actuator characteristics or detection characteristics may be obtained.
- the thin plate layer 22 preferably has an average particle diameter of crystals of 0.1 to 2 ⁇ m. More preferably, the thin plate layer 22 is desirably composed of a ceramic material having an average particle diameter of not more than 1 ⁇ m.
- Those usable to obtain the integrated fired product of ceramics to give the main sensor body comprising the thin plate layer 22 and the substrate layer 24 (and the spacer layer 26 ) as described above include, for example, a green sheet stacking method for stacking, in a state of green sheets, the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 , as well as various molding methods based on the use of a mold, such as pressure molding, casting molding, and injection molding, and processing or machining methods for forming, for example, the vibrator 2 , the support base 4 , and the first to third plate-shaped sections 6 , 8 , 10 by means of machining processing such as ultrasonic, cutting, and grinding processing methods.
- machining processing such as ultrasonic, cutting, and grinding processing methods.
- the green sheet stacking method is preferably based on the use of first, second, and third green sheets for providing the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 respectively.
- a method is adopted, in which the first, second, and third green sheets are stacked by means of thermal adhesion under a pressure, and then they are integrated with each other by firing. It is preferable to use, as the first to third green sheets, green sheets which at least have the same degree of percentage of contraction by firing, upon the firing and integration.
- the green sheet stacking method as described above specifically includes the following three methods.
- the first to third green sheets are formed to have shapes corresponding to the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 shown in FIG. 2 respectively. They are stacked and integrated with each other, followed by firing to produce an integrated fired product.
- the piezoelectric/electrostrictive elements 12 , 14 are formed in an integrated manner at predetermined regions on the thin plate layer 22 in accordance with the film formation method.
- the first green sheet, to which the shape of the thin plate layer 22 is not given is stacked and integrated with the second and third green sheets having shapes corresponding to the substrate layer 24 and the spacer layer 26 , and they are fired to obtain an integrated fired product.
- the shape of the thin plate layer 22 is realized by means of, for example, laser machining and ultrasonic machining, and then the piezoelectric/electrostrictive elements are formed in an integrated manner at predetermined regions on the thin plate layer 22 .
- the first green sheet, to which the shape of the thin plate layer 22 is not given is used.
- the first green sheet is stacked and integrated with the second and third green sheets having shapes corresponding to the substrate layer 24 and the spacer layer 26 , followed by firing to produce an integrated fired product.
- Piezoelectric/electrostrictive elements are formed in an integrated manner at predetermined regions of fired product portions of the first green sheet.
- the shape of the thin plate layer 22 is realized by means of, for example, laser machining and ultrasonic machining.
- the objective vibration gyro sensor is obtained.
- the present invention advantageously adopts the last-mentioned third method in order to avoid deformation which would be caused by the heat treatment during formation of the piezoelectric/electrostrictive elements.
- the shapes of the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 are preferably realized by using the method in which the green sheets are shaped to give such shapes, or by adopting, for example, laser machining, press working with a mold, and ultrasonic machining. Especially, the press working with a mold is advantageously used, because this method is excellent in mass production performance and integration performance.
- FIG. 17 shows an example of the desirable production technique (third method) for the vibration gyro sensor in accordance with the green sheet stacking method as described above.
- a first green sheet 52 for giving the thin plate layer 22 is not processed into the shape of the thin plate layer 22 at all.
- the first green sheet 52 is merely used as one thin plate having a rectangular configuration.
- a second green sheet 54 for giving the substrate layer 24 is processed into the shape corresponding to the shape of the substrate layer 24 .
- a third green sheet 56 for giving the spacer layer 26 is also processed into the shape corresponding to the shape of the spacer layer 26 .
- the first, second, and third green sheets 52 , 54 , 56 are stacked, and then they are fired and integrated into one unit.
- the piezoelectric/electrostrictive elements 12 , 14 are formed in an integrated manner on the predetermined regions on the thin plate layer 22 of the obtained fired product 58 in accordance with the film formation method as described later on. Subsequently, cutting processing is applied to portions of the thin plate layer 22 of the integrated fired product 58 by means of, for example, laser machining or ultrasonic machining. Thus the vibration gyro sensor as shown in FIG. 1 is completed.
- the order of the step of forming the piezoelectric/electrostrictive elements 12 , 14 and the step of processing the thin plate layer 22 is inverted, and the piezoelectric/electrostrictive elements 12 , 14 are formed in an integrated manner.
- the vibration gyro sensor as shown in FIG. 1 is completed.
- the vibration gyro sensor is obtained by stacking the first, second, and third green sheets 52 , 54 , 56 as described above, it is extremely easy to form the thin plate-shaped excisable section 16 extending from the forward end of the vibrator 2 by considering the shape of the thin plate layer 22 .
- the resonance frequency is measured, and the excisable section 16 formed at the forward end of the vibrator 2 is cut (excised) by means of, for example, laser machining and ultrasonic machining, if necessary.
- the resonance frequency can be finely adjusted with ease.
- the vibration gyro sensor shown in FIG. 1 is constructed such that the second green sheet 54 for giving the substrate layer 24 has a discontinuous structure of a form in which the portions for giving the vibrators 2 , 2 are separated, because the first plate-shaped sections 6 , 6 are formed by the thin plate layer 22 which is given by the first green sheet 52 . For this reason, it is difficult to position such discontinuous sections. Further, there is an implicit problem that deformation tends to occur during the firing and the heat treatment performed when the piezoelectric/electrostrictive elements are formed. Therefore, a technique is preferably adopted, in which a continuous green sheet is prepared and used during stacking, and discontinuous sections as described above are formed after completion of the stacking and integration or the firing and integration. An example of such a technique is shown in FIG. 18.
- FIG. 18 shows one of effective techniques to produce the vibration gyro sensor shown in FIG. 7.
- a second green sheet 54 for giving the substrate layer 24 is provided as a continuous sheet as shown in FIG. 18.
- sections 58 , 58 for forming the vibrators 2 , 2 are connected via connecting sections 62 , 62 to a section 60 for forming the attachment frame 30 , and thus the second green sheet 54 is used in a state including no discontinuous portion.
- the second green sheet 54 is stacked together with a first green sheet 52 and a third green sheet 56 , and they are fired and integrated with each other.
- the piezoelectric/electrostrictive elements 12 , 14 are formed in an integrated manner thereon, followed by performing machining for the thin plate layer 22 given by the first green sheet 52 .
- the connecting sections 62 , 62 which connect the vibrators 2 , 2 and the attachment frame 30 , are cut by means of, for example, laser machining or ultrasonic machining to make separation from the attachment frame 30 .
- cut sections 64 , 64 are formed from the connecting sections 62 , 62 , the vibrators 2 , 2 are released from restriction by the attachment frame 30 .
- the vibration gyro sensor shown in FIG. 7 is completed.
- the structure, in which any discontinuous section is not exist in the second green sheet 54 as described above, may be realized not only for the sensors having the structure which includes the attachment frame 30 , 36 , 38 and the frame 32 so that the vibrators 2 , 2 are surrounded as shown in FIGS. 7 to 16 , but also for the sensors having the structure including the support bar 28 provided between the two vibrators 2 , 2 as shown in FIGS. 5 and 6 such that connecting sections 62 , 62 are formed between the vibrators 2 , 2 and the support bar 28 , and they are finally cut at the cut sections 64 , 64 .
- the piezoelectric/electrostrictive elements 12 , 14 are formed on the predetermined regions on the thin plate layer 22 as follows.
- the electrode films 12 a, 12 c and the piezoelectric/electrostrictive film 12 b composed of respective materials on the predetermined regions on the thin plate layer 22 it is possible to appropriately adopt various known film formation methods including, for example, thick film methods such as screen printing, application methods such as dipping, and thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating.
- thick film methods such as screen printing
- application methods such as dipping
- thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating.
- ion beam sputtering
- CVD chemical vapor deposition
- plating there is no limitation thereto at all.
- the piezoelectric/electrostrictive film 12 b it is preferable to adopt techniques based on, for example, screen printing, dipping, and application.
- the film can be formed on the thin plate layer 22 by using a paste or a slurry comprising, as a major component, piezoelectric/electrostrictive ceramic particles, in which good operation characteristics can be obtained.
- the piezoelectric/electrostrictive element 12 , 14 is formed in accordance with the film formation method as described above, the element can be integrated with the thin plate layer 22 without using any adhesive. Accordingly, the use of the film formation method is especially preferred because the reliability and the reproducibility are excellent, and it is easy to achieve integration.
- the shape of such a film is formed by means of pattern formation by using, for example, the screen printing method and the photolithography method. Alternatively, the pattern may be formed by removing unnecessary portions by using mechanical processing methods such as laser processing, slicing, and ultrasonic processing.
- the shape of the film and the structure of the piezoelectric/electrostrictive element 12 , 14 formed integrally on the predetermined region on the thin plate layer 22 in accordance with the film formation method are not limited at all, to which those hitherto known may be appropriately adopted.
- the structure based on the use of the lateral effect of the electric field-induced strain as shown in FIG. 3 it is possible to appropriately adopt those having a structure based on the use of the longitudinal effect of the electric field-induced strain. No problem occurs concerning the shape of the film.
- the shape of the film may be any of polygonal configurations such as triangles and rectangles, circular configurations such as circles, ellipses, and rings, comb-shaped configurations, lattice-shaped configurations, and special configurations obtained by combining the foregoing configurations.
- the respective films 12 a, 12 b, 12 c which are formed on the first and third plate-shaped sections 6 , 10 given by the thin plate layer 22 , may be heat-treated every time when each film is formed so that the integrated structure is established together with the respective plate-shaped sections. Alternatively, all of the films may be formed, and then they may be simultaneously heat-treated so that the respective films may be simultaneously joined with the plate-shaped section in an integrated manner.
- the heat treatment is not necessarily indispensable to achieve integration in some cases.
- the heat treatment temperature to integrate the films formed as described above and the plate-shaped section a temperature of about 800° C. to 1400° C. is generally adopted, and preferably, a temperature within a range of 1000° C. to 1400° C. is advantageously selected.
- the piezoelectric/electrostrictive film 12 b is heat-treated, it is preferable to perform the heat treatment while controlling the atmosphere by using an evaporation source composed of a piezoelectric/electrostrictive material together so that the composition of the piezoelectric/electrostrictive film is not unstable at a high temperature.
- the material for the electrode films 12 a, 12 c for constructing the piezoelectric/electrostrictive element produced in accordance with the foregoing method is not specifically limited provided that the material is a conductor which can withstand the oxidizable atmosphere at a high temperature of a degree of the heat treatment temperature and the firing temperature.
- the material may be a simple substance of metal or an alloy.
- the material may be a mixture of a metal or an alloy and an additive such as an insulative ceramic and glass.
- no problem occurs when the material is a conductive ceramic. More appropriately, it is preferable to use electrode materials comprising major components of high melting point noble metals such as platinum, palladium, and rhodium, and alloys such as silver-palladium, silver-platinum, and platinum-palladium.
- the mixture described above it is desirable to use, as the ceramic to be added to the metal and the alloy, the same material as the material for constructing the first plate-shaped section and the third plate-shaped section or the piezoelectric/electrostrictive material described later on.
- the same material as the material for the plate-shaped section is preferably added in an amount of 5 to 30% by volume.
- the same material as the piezoelectric/electrostrictive material is preferably added in an amount of about 5 to 20% by volume.
- the mixture which is obtained by mixing the metal or the alloy described above with the material for constructing the plate-shaped section and the piezoelectric/electrostrictive material, is advantageously used to form the objective electrode.
- the electrodes 12 a, 12 c which are formed by using the material as described above, are allowed to have appropriate thicknesses depending on the use or application.
- the electrode in the case of the type based on the use of the lateral effect of the electric field-induced strain, the electrode is generally formed to have a thickness of not more than 15 ⁇ m, and preferably not more than 5 ⁇ m.
- the electrode in the case of the type based on the use of the longitudinal effect of the electric field-induced strain, the electrode is appropriately formed to have a thickness of not less than 3 ⁇ m, preferably not less than 10 ⁇ m, and more preferably not less than 20 ⁇ m.
- any material may be used as the piezoelectric/electrostrictive material to give the film-shaped piezoelectric/electrostrictive layer 12 b for constructing the piezoelectric/electrostrictive elements 12 , 14 , provided that the material exhibits the electric field-induced strain such as the piezoelectric or electrostrictive effect.
- the material may be crystalline materials, or amorphous materials. No problem occurs when the material is any of semiconductor materials, dielectric ceramic materials, or ferroelectric ceramic materials.
- the material may be materials which require the polarization treatment, or materials which do not require the polarization treatment.
- those preferably used as the piezoelectric/electrostrictive material employed in the present invention include, for example, materials comprising a major component of lead zirconate titanate (PZT system), materials comprising a major component of lead magnesium niobate (PMN system), materials comprising a major component of lead nickel niobate (PNN system), materials comprising a major component of lead zinc niobate, materials comprising a major component of lead manganese niobate, materials comprising a major component of lead antimony stannate, materials comprising a major component of lead titanate, materials comprising a major component of barium titanate, and composite materials thereof.
- PZT system lead zirconate titanate
- PMN system lead magnesium niobate
- PNN system materials comprising a major component of lead nickel niobate
- materials comprising a major component of lead zinc niobate materials comprising a major component of lead manganese niobat
- the thickness of the piezoelectric/electrostrictive element 12 , 14 constructed as described above is generally not more than 100 ⁇ m, preferably not more than 50 ⁇ m, and more preferably not more than 30 ⁇ m.
- the spacer section 18 is provided, for example, for the support base 4 , the attachment frame 30 , 36 , or the attachment section 34 so that the respective vibrators 2 , 2 do not interfere with the attachment plane even when the vibrators 2 , 2 makes vibration for detection.
- the support base 4 , the attachment frame 30 , 36 , or the attachment section 34 is fixed by using the bolts.
- Those usable as the adhesive include, for example, those of the epoxy resin type, the acrylic resin type, the synthetic rubber type, the hot melt type, the cyanoacrylate type, and the polyurethane resin type.
- the first plate-shaped section 6 on which the detecting piezoelectric/electrostrictive element 12 is formed in the integrated manner, is provided at the intermediate portion or the proximal end of the vibrator 2 .
- FIGS. 20 and 21 it is possible to provide the first plate-shaped section 6 at the forward end of the vibrator 2 to give an integrated structure continued to the excisable section 16 .
- the Coriolis force applied to the detecting piezoelectric/electrostrictive element 12 is lowered, and the sensitivity is decreased.
- this structure has a feature that it is advantageous concerning achievement of a compact size and concerning breakage.
- the vibration gyro sensor comprises a rectangular parallelepiped-shaped support base 100 with its longitudinal direction extending in a certain direction (X direction in FIG. 22), two vibrators 102 A, 102 B provided on one side surface of the support base 100 and having their direction of major axes extending in a direction (Y direction in FIG. 22) perpendicular to the certain direction, two vibrators 102 C, 102 D provided on another side surface of the support base 100 and having their direction of major axes extending in the Y direction, and a frame 104 having its frame surface parallel to a plane including the X and Y directions, for surrounding the support base 100 and the four vibrators 102 A to 102 D.
- the respective two vibrators 102 A, 102 B and 102 C, 102 D are supported by the support base 100 at the respective side surfaces so that they extend in parallel to one another while giving a predetermined spacing width “d”.
- Each of the vibrators 102 A to 102 D has a rectangular parallelepiped-shaped main vibrator body 106 , and a thin-walled plate-shaped connecting section (second plate-shaped section) 108 for connecting the main vibrator body 106 to the support base 100 .
- the connecting section 108 extends from a central portion in the widthwise direction of an end surface of the main vibrator body 106 on the side of the support base 100 to the support base 100 .
- the height of the connecting section 108 is approximately the same as that of the main vibrator body 106 , and the width thereof is designed to be smaller than the width of the main vibrator body 106 , in the same manner as described in the first embodiment (see FIG. 1).
- An opening 110 which has an approximately rectangular planar configuration, is formed through the frame 104 at its central portion.
- the opening 110 penetrates through the frame 104 in its direction of height, and it has an opening area of a degree to make it possible to surround the support base 100 and the four vibrators 102 A to 102 D.
- the opening 110 has rectangular cutouts 112 at portions corresponding to both longitudinal ends of the support base 100 .
- the distance between bottoms of the respective cutouts 112 is designed to be longer than the length of the support base 100 in the longitudinal direction.
- Side surfaces of the respective cutouts 112 are opposed, at portions near to the opening 110 , to the side surfaces of the support base 100 .
- the support base 100 is formed such that its both ends in the longitudinal direction are inserted into the corresponding cutouts 112 respectively.
- the respective two vibrators 102 A, 102 B and 102 C, 102 D which are connected to the both side surfaces of the support base 100 , are provided with plate-shaped driving sections (third plate-shaped sections) 114 which are thin-walled in the direction of height and formed between the main vibrator bodies 106 respectively.
- each of the driving sections 114 has its upper surface which is disposed on a side of the upper surface of the main vibrator body 106 , and which is disposed at a position nearest to the connecting sections 108 .
- the respective driving sections 114 are actually disposed on the side of the upper surface of the main vibrator body 106 . However, strictly speaking, they are convex upward or convex downward, giving a structure in which they are not in an identical plane (plate spring structure).
- Plate-shaped sections 116 which are thin-walled in their direction of height, are provided between portions of the both side surfaces of the support base 100 in the vicinity of the both ends in the longitudinal direction and side surfaces of the cutouts 112 opposing to the portions.
- the upper surfaces of the respective plate-shaped sections 116 are depicted in a state in which they are flush with the upper surface of the support base 100 and the upper surface of the frame 104 .
- the respective plate-shaped sections 116 are disposed on the side of the upper surface of the support base 100 and on the side of the upper surface of the frame 104 , they are convex upward or convex downward. Strictly speaking, the respective plate-shaped sections 116 have a structure in which they are not disposed in an identical plane (plate spring structure).
- the support base 100 , the four vibrators 102 A to 102 D, the frame 104 , the four connecting sections 108 , the two driving sections 114 , and the four plate-shaped sections 116 are constructed by an integrated fired product made of ceramics.
- the vibration gyro sensor further comprises driving piezoelectric/electrostrictive elements 118 formed on the driving sections 114 , and detecting piezoelectric/electrostrictive elements 120 formed on the plate-shaped sections 116 .
- driving means 122 for vibrating the vibrators 102 in an excited manner are constructed by the driving sections 114 and the driving piezoelectric/electrostrictive elements 118
- detecting sections 124 are constructed by the plate-shaped sections 116 and the detecting piezoelectric/electrostrictive elements 120 .
- the driving piezoelectric/electrostrictive elements 118 are operated by applying an electric power thereto, the respective two vibrators 102 A, 102 B and 102 C, 102 D make vibration while being bent in mutually opposite directions in the X axis direction, i.e., in directions to make mutual approach or separation in the arrangement plane thereof.
- the connecting sections 108 provided between the main vibrator bodies 106 and the support base 100 will now be described.
- the aspect ratio (width: height) of the connecting section 108 is preferably within a range of 1:1.2 to 1:1000, and more preferably within a range of 1:1.8 to 1:50.
- the aspect ratio should be designed within the foregoing range because of the following reason. Namely, if the aspect ratio of the connecting section 108 is larger than 1:1.2, unnecessary vibration in the Z axis direction tends to occur in the vibrators 102 A to 102 D. As a result, unnecessary vibration tends to occur in the detecting sections 124 . On the other hand, if the aspect ratio is smaller than 1:1000, it is difficult to process and machine the connecting sections 108 . As a result, the processing accuracy is deteriorated.
- the vibration gyro sensor when the driving piezoelectric/electrostrictive elements 118 are operated, the driving sections 114 undergo deformation.
- the respective two vibrators 102 A, 102 B and 102 C, 102 D make excited vibration (lateral vibration) in mutually opposite directions in the X axis direction.
- all of the vibrators 102 , the support base 100 , and the detecting sections 124 are constructed by the integrated fired product of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. Accordingly, the characteristics of the sensor are not affected by any ambient magnetic field.
- the detecting section 124 is constructed as having the plate-shaped section 116 which is more thin-walled than the main vibrator body 106 in its direction of height so that it has a structure having low rigidity. Therefore, when the vibration is caused around the Z axis by the angular velocity as described above, a large strain or distortion is obtained in the plate-shaped section 116 . Thus it is possible to greatly improve the detection sensitivity of the detecting piezoelectric/electrostrictive element 120 formed on the plate-shaped section 116 .
- the vibration is generated in the detecting section 124 only when the angular velocity is applied. Therefore, the output (null voltage), which is obtained from the detecting piezoelectric/electrostrictive element 120 in a state in which no angular velocity is applied, is extremely small. Thus the detection sensitivity is greatly improved. Moreover, the probability of occurrence of fatigue fracture at the detecting section 124 due to vibration is lowered, and it is possible to contemplate a long service life of the vibration gyro sensor.
- the vibration gyro sensor has the structure not for measuring the angular velocity around the major axis of the vibrator 106 (around the Y axis), but for measuring the angular velocity around the axis perpendicular to the plane which includes the certain direction and the extending direction of the support base 100 (around the Z axis). Therefore, the vibrators 102 , the support base 100 , and the frame 104 can be made thin in their direction of height. Thus it is possible to facilitate realization of a compact size and a light weight of the vibration gyro sensor.
- FIG. 23 Components or parts corresponding to those shown in FIG. 22 are designated by the same reference numerals, duplicate explanation of which will be omitted.
- the vibration gyro sensor according to the sixteenth embodiment has approximately the same structure as that of the vibration gyro sensor according to the fifteenth embodiment (see FIG. 22). However, the detecting sections 124 are different in the following points.
- the detecting section 124 comprises a ring member 130 formed of ceramics in an integrated manner between a side surface of the cutout 112 and a portion of both side surfaces of the support base 100 in the vicinity of the both ends in the longitudinal direction, a plate-shaped section 116 provided in an integrated and bridged manner in parallel to the extending direction of the support base 100 (X axis direction) in the ring member 130 , and a detecting piezoelectric/electrostrictive element 120 formed on the plate-shaped section 116 .
- the vibration gyro sensor according to the sixteenth embodiment is operated as follows. Namely when an angular velocity is applied around the axis perpendicular to the plane including the certain direction and the extending direction of the support base 100 (around the Z axis) in a state in which the respective two vibrators 102 A, 102 B and 102 C, 102 D are vibrated in accordance with the operation of the driving piezoelectric/electrostrictive elements 118 , a force acts in the Y axis direction on the detecting sections 124 . The action of the force causes the ring members 130 to make vibration while forming elliptic configurations with their major or minor axis directed in the Y axis direction.
- the vibration of the ring members 130 in the Y axis direction is detected as an electromotive force (voltage) by the detecting piezoelectric/electrostrictive elements 120 .
- the strain in the detecting sections 124 in the Y axis direction is indirectly measured via the deformation of the ring members 130 by using the detecting piezoelectric/electrostrictive elements 120 .
- This embodiment provides an effect that the vibration gyro sensor is excellent in durability.
- the resonance frequency is adjusted in the same manner as, for example, the vibration gyro sensor according to the first embodiment described above (see FIG. 1).
- the adjustment for the resonance frequency will be specifically explained with reference to FIGS. 24 and 25, as represented by the vibration gyro sensor according to the fifteenth embodiment.
- the gyro sensor according to the fifteenth embodiment is actually constructed as follows in order to adjust the resonance frequency. Namely, as shown in FIG. 24, thin-walled first projections 132 , which protrude outwardly from respective free ends of the respective two vibrators 102 A, 102 B and 102 C, 102 D, are formed of ceramics in an integrated manner. Further, thin-walled second projections 134 , which protrude outwardly from both ends of the support base 100 in the longitudinal direction, are formed of ceramics in an integrated manner.
- the resonance frequency for driving is adjusted by trimming-treating the first projections 132
- the resonance frequency for detection is adjusted by trimming-treating the second projections 134 .
- the resonance frequency for driving can be adjusted by applying a trimming treatment (excising treatment) to the first projections 132
- the resonance frequency for detection can be adjusted by applying a trimming treatment (excising treatment) to the second projections 134 .
- the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving.
- the shapes of the first and second projections 132 , 134 may by constructed as follows.
- the first and second projections 132 , 134 may be constructed as plate-shaped and thin-walled in the direction of height with respect to the respective main vibrator bodies 106 .
- the first and second projections 132 , 134 may be constructed as plate-shaped and thin-walled in the extending direction of the support base 100 (X axis direction) with respect to the respective main vibrator bodies 106 .
- the shape shown in FIG. 24 is advantageous in that the trimming treatment can be easily performed by means of, for example, laser beam scanning over the upper surface.
- regions to be subjected to the trimming treatment are disposed over entire surfaces perpendicular to the direction of vibration of the respective two vibrators 102 A, 102 B and 102 C, 102 D, and hence an extremely excellent mass balance is obtained.
- the trimming treatment is performed, for example, by applying percussion such as ultrasonic waves after laser radiation so that unnecessary portions are excised.
- the resonance frequency for detection is considerably affected.
- the resonance frequency for driving is not affected. Therefore, when the resonance frequency is actually adjusted, it is preferable that the resonance frequency for driving is firstly adjusted by trimming-treating the first projections 132 , and then the resonance frequency for detection is adjusted by trimming-treating the second projections 134 .
- the vibration gyro sensor according to the seventeenth embodiment is constructed in approximately the same manner as the vibration gyro sensor according to the fifteenth embodiment. However, the former is different from the latter in that plate-shaped driving sections 114 of the driving means 122 are arranged on lines for connecting centers of gravity of the respective main vibrator bodies 106 respectively.
- the respective two vibrators 102 A, 102 B and 102 C, 102 D can efficiently make mutual approach and separation, as compared with the vibration gyro sensor including the driving sections 114 disposed in the vicinity of the connecting sections 108 (for example, the vibration gyro sensor according to the fifteenth embodiment). Accordingly, this embodiment is advantageous in that the detection sensitivity in the detecting sections 124 can be improved.
- the adjustment for the resonance frequency by means of the trimming treatment for the vibration gyro sensor may be performed in another way, in place of the trimming treatment for the first and second projections 132 , 134 described above (see FIGS. 24 and 25).
- the driving sections 114 provided between the respective main vibrator bodies 106 , and the plate-shaped sections 116 of the detecting sections 124 provided between the support base 100 and the frame 104 are allowed to have wide widths respectively beforehand.
- the widths of the driving sections 114 and the plate-shaped sections 116 are appropriately changed.
- the resonance frequencies for driving and detection may be adjusted.
- the resonance frequencies for driving and detection are not adjusted by changing the masses of the main vibrator bodies 106 and the support base 100 , but the resonance frequencies for driving and detection are adjusted by changing spring constants of the driving sections 114 and the plate-shaped sections 116 .
- the two plate-shaped driving sections 114 disposed between the respective main vibrator bodies 106 are excised by means of, for example, laser machining or ultrasonic machining.
- the four plate-shaped sections 116 disposed between the support base 100 and the frame 104 are excised by means of, for example, laser machining or ultrasonic machining.
- the resonance frequency is easily adjusted because the region subjected to the trimming treatment is thin-walled.
- the method of this embodiment is also advantageous in that the resonance frequency for driving and the resonance frequency for detection can be adjusted completely-independently from each other.
- the fifteenth to seventeenth embodiments are illustrative of the formation of the driving section 114 between the main vibrator bodies 106 .
- the driving section 114 may be formed between the support base 100 and the main vibrator body 106 .
- FIGS. 28 and 29 show eighteenth and nineteenth embodiments.
- a vibration gyro sensor according to the nineteenth embodiment comprises driving sections 114 each of which is formed between a support base 100 and a portion corresponding to a region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction.
- the driving section 114 is not formed between the adjacent main vibrator bodies 106 . Accordingly, it is possible to narrow the spacing distance between the adjacent main vibrator bodies 106 , making it possible to facilitate realization of a compact size of the vibration gyro sensor.
- the connecting section 108 which is formed between each of the main vibrator bodies 106 and the support base 100 , is disposed at the position on each of the main vibrator bodies 106 , the position being located at the central portion of the end surface of the main vibrator body 106 on the side of the support base 100 .
- the position is not necessarily indispensable that the position is the central portion.
- the position, at which the connecting section 108 is formed on each of the main vibrator bodies 106 may be disposed at a portion of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the frame 106 (twentieth embodiment).
- the position may be a portion corresponding to a region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction.
- a vibration gyro sensor according to a twenty-first embodiment shown in FIG. 31 is constructed such that the vibration gyro sensor according to the seventeenth embodiment shown in FIG. 26 further comprises reference means 140 provided in the vicinity of the connecting sections 108 of the respective main vibrator bodies 106 .
- the reference means 140 is constructed in approximately the same manner as the driving means 122 , comprising a plate-shaped reference section (fourth plate-shaped section) 144 which is thin-walled in the direction of height, and a reference piezoelectric/electrostrictive element 142 formed on the reference section 144 .
- the reference section 144 is formed of ceramics in an integrated manner in the same manner as the driving section 114 .
- a signal which is obtained from the reference piezoelectric/electrostrictive element 142 of the reference means 140 , is fed to the driving piezoelectric/electrostrictive element 118 in the feedback manner to give constant vibration of the driving means 122 formed on the line for connecting the centers of gravity of the respective main vibrator bodies 106 .
- the plate-shaped section provided on the line for connecting the centers of gravity of the respective main vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122
- the plate-shaped section provided in the vicinity of the connecting section 108 of each of the main vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140 .
- a vibration gyro sensor according to a twenty-second embodiment shown in FIG. 32 is constructed such that the vibration gyro sensor according to the eighteenth embodiment shown in FIG. 28 further comprises reference means 140 provided between the support base 100 and a portion corresponding to a region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction.
- a signal which is obtained from a reference piezoelectric/electrostrictive element 142 of, the reference means 140 , is fed to the driving piezoelectric/electrostrictive element 118 in a feedback manner to give constant vibration of the driving means 122 provided between the support base 100 and a portion of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the frame 104 .
- the plate-shaped section provided between the support-base 100 and the portion of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the frame 104 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122
- the plate-shaped section provided between the support base 100 and the portion corresponding to the region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140 .
- a vibration gyro sensor according to a twenty-third embodiment shown in FIG. 33 is constructed such that the vibration gyro sensor according to the seventeenth embodiment shown in FIG. 26 further comprises a reference means 140 provided between the support base 100 and a portion corresponding to a region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction.
- a signal which is obtained from a reference piezoelectric/electrostrictive element 142 of the reference means 140 , is fed to the driving piezoelectric/electrostrictive element 118 in a feedback manner to give constant vibration of the driving means 122 formed on the line for connecting the centers of gravity of the respective main vibrator bodies 106 .
- the plate-shaped section provided on the line for connecting the centers of gravity of the respective main vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122
- the plate-shaped section provided between the support base 100 and the portion corresponding to the region of the end surface of the main vibrator body 106 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140 .
- the driving means 122 and the reference means 140 are disposed in an inverse manner.
- any of the vibration gyro sensors according to the first to twenty-third embodiments has the structure of the so-called forced vibration system in which the vibrator 2 (or 102 ) is directly vibrated by the driving section.
- FIGS. 34 to 36 it is allowable to adopt structures based on the free vibration system.
- This vibration gyro sensor is illustrative of a structure comprising plate-shaped vibration-applying sections (fifth plate-shaped sections) 150 arranged between a support base 100 and respective main vibrator bodies 106 and extending in parallel to the longitudinal direction of the support base 100 , thin-walled plate-shaped first connecting sections (sixth plate-shaped sections) 152 for connecting the support base 100 and the vibration-applying sections 150 , thin-walled plate-shaped connecting sections (seventh plate-shaped sections) 154 for connecting the main vibrator bodies 106 and the vibration-applying sections 150 , and driving means 122 provided between the respective vibration-applying sections 150 .
- the first and second connecting sections 152 , 154 have approximately the same dimensional relation as those of the connecting sections 108 of the vibration gyro sensors according to the fifteenth to twenty-third embodiments described above.
- the height of the vibration-applying section 150 is approximately the same as that of the main vibrator body 106 .
- the width of the vibration-applying section 150 is designed to be smaller than the width of the main vibrator body 106 and slightly larger than those of the first and second connecting sections 152 , 154 .
- a vibration gyro sensor according to a twenty-fifth embodiment shown in FIG. 35 is constructed in approximately the same manner as the vibration gyro sensor according to the twenty-fourth embodiment. However, the former is different from the latter in that the driving means 122 is provided between the support base 10 and a portion of the end surface of the vibration-applying section 150 on the side of the support base 100 in the vicinity of the frame 104 .
- a vibration gyro sensor according to a twenty-sixth embodiment shown in FIG. 36 is constructed in approximately the same manner as the vibration gyro sensor according to the twenty-fourth embodiment. However, the former is different from the latter in that the driving means 122 is provided between the support base 10 and a portion corresponding to a region of the end surface of the vibration-applying section 150 on the side of the support base 100 in the vicinity of the center of the support base 100 in the longitudinal direction.
- the vibrators 102 A to 102 D are indirectly vibrated by giving vibration to the vibration-applying sections 150 disposed between the main vibrator bodies 106 and the support base 100 by the aid of the driving means 122 .
- These vibration gyro sensors are advantageous in the following points because the main vibrator bodies 106 are scarcely affected by the driving sections 114 . Namely, (1) it is easy to obtain large amplitude when the vibrators 102 A to 102 D are vibrated, and (2) the vibration waveform scarcely suffers disturbance in the vibrators 102 A to 102 D, and it is possible to obtain a vibration waveform following the regular sine wave.
- Vibration gyro sensors which have been hitherto used, employ the elinvar alloy for the vibrator in many cases, in which the bulky piezoelectric/electrostrictive element formed with the electrodes is fixed to the vibrator by means of adhesion. Therefore, it is necessary to use, for example, solder or Ag paste for connecting external wiring to the electrodes of the piezoelectric/electrostrictive element. In this procedure, for example, the solder, the Ag paste, and the external wiring itself behave as added weights which greatly affect the vibration characteristics of the vibrator, making it difficult to produce the vibration gyro sensors.
- Vibration gyro sensors of another type is also known, in which a piezoelectric ceramic is used for the vibrator.
- vibration gyro sensors are not essentially different from the foregoing conventional vibration gyro sensors in that the lead wire is connected to the part which is used to make vibration. Problems arise in that (a) the connecting section to the external wiring is less reliable, and (b) the dispersion in production is large.
- the vibration gyro sensors according to the first to twenty-sixth embodiments described above are advantageous in that external wiring can be easily connected to the pair of electrodes of the respective piezoelectric/electrostrictive elements 118 , 120 .
- the vibration gyro sensor is constructed by the integrated fired product made of ceramics (non-conductive materials) except for the respective pairs of electrodes of the driving means 122 and the detecting sections 124 .
- the wiring formation pattern will be specifically explained below.
- the two wirings ( 160 , 162 ) and ( 164 , 166 ) which are led from the pairs of electrodes for constructing the piezoelectric/electrostrictive elements 118 of the driving means 122 provided between the respective main vibrator bodies 106 are formed such that they are led to the frame 104 via the upper surfaces of the main vibrator bodies 106 adjacent to the respective electrodes, the upper surfaces of the connecting sections 108 , the upper surface of the support base 100 , and the upper surfaces of the plate-shaped sections 116 of the detecting sections 124 adjacent to the vibrators 102 A, 102 B.
- the two wirings ( 168 , 170 ), ( 172 , 174 ), ( 176 , 178 ) and ( 180 , 182 ) which are led from the pairs of electrodes of the piezoelectric/electrostrictive elements 120 of the respective detecting sections 124 are formed such that they are led to the frame 104 from the respective detecting sections 124 .
- the material for constructing the electrodes and the wirings is not specifically limited provided that the material is a conductor which can withstand the oxidizable atmosphere at a high temperature of a degree of the heat treatment temperature and the firing temperature.
- the material may be a simple substance of metal or an alloy.
- the material may be a mixture of a metal or an alloy and an additive such as an insulative ceramic and glass.
- no problem occurs when the material is a conductive ceramic.
- electrode materials comprising major components of high melting point noble metals such as platinum, palladium, and rhodium, and alloys such as silver-palladium, silver-platinum, and platinum-palladium.
- the method for forming the electrodes and the wirings it is possible to appropriately adopt, for example, thick film methods such as screen printing, application methods such as dipping, and thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating.
- thick film methods such as screen printing
- application methods such as dipping
- thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating.
- thick film methods such as screen printing
- application methods such as dipping
- thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating.
- a vibration gyro sensor according to a twenty-seventh embodiment shown in FIG. 38 is constructed in approximately the same manner as the vibration gyro sensor according to the first embodiment shown in FIG. 1.
- the former is different from the latter in that a third plate-shaped section 10 , on which a driving piezoelectric/electrostrictive element 14 is provided, is formed in an integrated manner so that the two second plate-shaped sections 8 are bridged with the third plate-shaped section 10 .
- a vibration gyro sensor according to a twenty-eighth embodiment shown in FIG. 39 is constructed in approximately the same manner as the vibration gyro sensor according to the third embodiment shown in FIG. 5.
- the former is different from the latter in that thin-walled third plate-shaped sections 10 are formed in an integrated manner between the support bar 28 and the second plate-shaped sections 8 disposed at the right and left thereof, and driving piezoelectric/electrostrictive elements 14 are formed on the third plate-shaped sections 10 respectively so that the right and left two vibrators 2 are vibrated in an excited manner in mutually opposite directions by operating the driving piezoelectric/electrostrictive elements 14 respectively.
- a vibration gyro sensor according to a twenty-ninth embodiment shown in FIG. 40 is constructed in approximately the same manner as the vibration gyro sensor according to the fifth embodiment shown in FIG. 7.
- the former is different from the latter in that thin-walled third plate-shaped sections 10 are formed in an integrated manner between the two second plate-shaped sections 8 and sides of the attachment frame 30 opposing thereto, and driving piezoelectric/electrostrictive elements 14 are formed in an integrated manner on the third plate-shaped sections 10 in accordance with the film formation method.
- a vibration gyro sensor according to a thirtieth embodiment shown in FIG. 41 is constructed in approximately the same manner as the vibration gyro sensor according to the seventh embodiment shown in FIG. 9.
- the former is different from the latter in that a thin-walled third plate-shaped section 10 is formed in an integrated manner between the two second plate-shaped sections 8 disposed in the attachment frame 30 having the rectangular frame structure, and a driving piezoelectric/electrostrictive element 14 is formed in an integrated manner on the third plate-shaped section 10 in accordance with the film formation method.
- the vibration gyro sensors according to the twenty-seventh to thirtieth embodiments are constructed such that the vibrators 2 are not driven directly, but the second plate-shaped sections 8 are driven. Accordingly, the vibrators 2 can make vibration without being restricted by the third plate-shaped section 10 which constructs the driving means 122 . Therefore, Q factor of the vibrator 2 is increased, and hence the vibration is not readily attenuated. Thus it is easy to handle the detection signal detected by the detecting piezoelectric/electrostrictive element 12 . Further, the amplitude of vibration of the vibrator 2 is increased, and it is possible to further improve the sensitivity.
- the first plate-shaped section 6 for constructing the detecting section is formed to be more thin-walled than the vibrator 2 , and they are integrated with each other in structure. However, in view of the function, the first plate-shaped section 6 or the detecting section is constructed distinctly from the vibrator 2 .
- a vibration gyro sensor is constructed in an integrated manner by using an integrated fired product made of ceramics to have a structure comprising a rectangular block-shaped support base 4 having a predetermined thickness, two second plate-shaped sections 8 which extend from proximal ends on a longitudinal side surface of the support base 4 in a direction perpendicular to the longitudinal side surface of the support base 4 while being separated from each other by a predetermined spacing distance, two first plate-shaped sections 6 each having an approximately strip-shaped (wide and lengthy) planar configuration which extend from proximal ends on upper portions of free ends of the respective second plate-shaped sections 8 in the direction perpendicular to the longitudinal side surface of the support base 4 while being separated from each other by a predetermined spacing distance (see FIG. 43), and a third plate-shaped section 10 having an approximately strip-shaped planar configuration formed to bridge the two second plate-shaped sections 8 therewith.
- vibrators 2 are constructed by the first plate-shaped
- the width of the second plate-shaped section 8 is thinner than the width of the first plate-shaped section 6 .
- the second plate-shaped section 8 is a thin-walled plate-shaped section having a principal surface which extends in the direction perpendicular to the first plate-shaped section 6 .
- the first plate-shaped section 6 (vibrator 2 ) is connected in an integrated manner to the support base 4 via the second plate-shaped section 8 .
- the third plate-shaped section 10 is connected in an integrated manner between portions of the second plate-shaped sections 8 in the vicinity of the support base 4 .
- detecting piezoelectric/electrostrictive elements 12 are formed on approximately entire surfaces of upper surfaces of the respective first plate-shaped sections 6 which are formed to be wide.
- a driving piezoelectric/electrostrictive element 14 is formed on an approximately entire surface of an upper surface of the third plate-shaped section 10 .
- the vibrator 2 is constructed by the wide and lengthy first plate-shaped section 6 . Accordingly, the vibrator 2 has a large mass and a large moment. As a result, the velocity ( ⁇ amplitude) brought about by the driving vibration is increased. Therefore, it is possible to further improve the sensitivity. Further, the detecting piezoelectric/electrostrictive element 12 is formed on the approximately entire surface of the first plate-shaped section 6 . Therefore, it is possible to accumulate a large amount of electric charge, and thus this embodiment is advantageous in the current detection system.
- a vibration gyro sensor according to a thirty-second embodiment shown in FIG. 44 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment (see FIG. 42). However, the former is different from the latter in that thick-walled block sections 70 are formed in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42 the first plate-shaped section 6 is directly formed on the second plate-shaped section 8 . Therefore, it is feared that the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 may be disadvantageous from a viewpoint of strength.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion. Accordingly, this embodiment is advantageous to improve the reliability.
- a vibration gyro sensor according to a thirty-third embodiment shown in FIG. 45 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42.
- the former is different from the latter in that the support base 4 is provided as a rectangular frame 32 .
- Two second plate-shaped sections 8 are formed in an integrated manner so that they extend from proximal ends disposed on one short side of inner frame wall surfaces of the frame 32 in a direction parallel to long sides of the frame 32 while being separated from each other by a predetermined spacing distance.
- the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42 includes the block-shaped support base 4 . Therefore, such a vibration gyro sensor suffers a problem concerning installation in that when the support base 4 is installed and fixed by using an adhesive or the like, the area for fixation is small, and it also suffers a problem concerning strength in that the rigidity of the support base 4 tends to be lowered, and the vibration is readily transmitted to the support bars 4 .
- the support base 4 is provided in the form of the frame 32 , and thus the degree of freedom for attachment is increased. Further, the rigidity is also improved. Therefore, the foregoing problems can be solved, and hence this embodiment is practically appropriate.
- a vibration gyro sensor according to a thirty-fourth embodiment shown in FIG. 46 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-third embodiment (FIG. 45). However, the former is different from the latter in that thick-walled block sections 70 are formed in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 . Further, this embodiment is advantageous from viewpoints of installation and rigidity because the frame 32 is used.
- a vibration gyro sensor according to a thirty-fifth embodiment shown in FIG. 47 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-third embodiment (FIG. 45).
- the former is different from the latter in that a plurality of recesses 72 are formed on the back surface of the first plate-shaped section 6 as shown in FIG. 48, and detecting piezoelectric/electrostrictive elements 12 are formed in an array of islands at positions on the upper surface of the first plate-shaped section 6 corresponding to the plurality of recesses 72 .
- the embodiment shown in FIG. 47 is illustrative of a structure in which the recess 72 has a circular contour, and the detecting piezoelectric/electrostrictive element 12 has a circular planar configuration.
- the strength is lowered at the portions of the first plate-shaped section 6 on which the recesses 72 are formed. Therefore, when the first plate-shaped section 6 is deformed by the Coriolis force, a strain, which is larger than that obtained at portions without having any recess 72 , is generated at the portions on which the recesses 72 are formed. Accordingly, a large detection output can be obtained by forming the detecting piezoelectric/electrostrictive elements 12 at the portions corresponding to the recesses 72 . Thus it is possible to further improve the sensitivity.
- a vibration gyro sensor according to a thirty-sixth embodiment shown in FIG. 49 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47.
- the former is different from the latter in that thick-walled block sections 70 are provided in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 . Further, this embodiment is advantageous from viewpoints of high reliability and improvement in sensitivity, because a large output can be obtained.
- the vibration gyro sensors according to the thirty-fifth and thirty-sixth embodiments described above are illustrative of the structure in which the detecting piezoelectric/electrostrictive elements 12 each having the approximately circular planar configuration are formed in the array of islands on the upper surface of the first plate-shaped section 6 .
- both of the contour of each of the recesses 72 (see FIG. 48) and the detecting piezoelectric/electrostrictive elements 12 may be square or rectangular (thirty-seventh and thirty-eighth embodiments).
- planar configuration of the recess 72 and the detecting piezoelectric/electrostrictive element 12 include, for example, circular and rectangular configurations as described above, as well as rhombic configurations.
- the shape of these components is not specifically limited.
- a vibration gyro sensor according to a thirty-ninth embodiment shown in FIG. 52 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42.
- the former is different from the latter in that an attachment section 74 for fixing the support base 4 is provided in an integrated manner on a surface of the support base 4 opposite to the surface on which the second plate-shaped sections 8 are formed, and a support section (fifth plate-shaped section) 76 , which is thin-walled in the widthwise direction of the support base 4 , is provided in an integrated manner between the support base 4 and the attachment section 74 .
- the vibration gyro sensor according to the thirty-ninth embodiment has a structure in which a tuning fork 78 is constructed by the support base 4 , the two second plate-shaped sections 8 , and the two vibrators 2 (first plate-shaped sections 6 ), and the tuning fork 78 is connected in an integrated manner to the attachment section 74 via the support section (fifth plate-shaped section) 76 .
- the mode which is obtained when the tuning fork 78 is supported by an arbitrary fixing means with a support rod and the tuning fork 78 is vibrated, includes a mode in which the two vibrators 2 of the tuning fork 78 are vibrated in mutually opposite directions, and a mode in which the two vibrators 2 are vibrated in an identical direction respectively.
- the mode which is required for the vibration gyro sensor, is the former mode (the mode of vibration in mutually opposite directions).
- the latter mode is an unnecessary mode for the vibration gyro sensor. Accordingly, when the frequency of the necessary mode is greatly different from the frequency of the unnecessary mode, they can be easily discriminated from each other, and the detection accuracy in the necessary mode can be improved.
- FIG. 53 shows how the frequency in the necessary mode and the frequency in the unnecessary mode change depending on the length of the support rod.
- a curve “a” indicates a characteristic of the necessary mode
- a curve “b” indicates a characteristic of the unnecessary mode.
- the support base 4 is connected in the integrated manner to the attachment section 74 via the support section 76 . Therefore, the support section 76 functions as the support rod, making it possible to improve the detection accuracy.
- a vibration gyro sensor according to a fortieth embodiment shown in FIG. 54 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-ninth embodiment shown in FIG. 52.
- the former is different from the latter in that thick-walled block sections 70 are provided in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 .
- the vibration gyro sensor has a tuning fork 78 which is constructed in an integrated manner on the support section 76 . Therefore, this embodiment is advantageous in order to improve the detection accuracy.
- a vibration gyro sensor according to a forty-first embodiment shown in FIG. 55 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-ninth embodiment shown in FIG. 52.
- the former is different from the latter in that the attachment section 76 has a form of a rectangular frame (hereinafter referred to as “attachment frame 80 ”).
- the support section 76 is formed in an integrated manner so that it extends from its proximal end disposed on one short side of inner frame wall surfaces of the attachment frame 80 in a direction parallel to long sides of the attachment frame 80 .
- a vibration gyro sensor according to a forty-second embodiment shown in FIG. 56 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-first embodiment shown in FIG. 55.
- the former is different from the latter in that thick-walled block sections 70 are provided in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 . Moreover, this embodiment is advantageous from viewpoints of installation and rigidity, because the attachment frame 80 is used.
- a vibration gyro sensor according to a forty-third embodiment shown in FIG. 57 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-first embodiment shown in FIG. 55.
- the former is different from the latter in that a plurality of recesses 72 are formed on the back surface of the first plate-shaped section 6 as shown in FIG. 48, and detecting piezoelectric/electrostrictive elements 12 are formed in an array of islands at positions on the upper surface of the first plate-shaped section 6 corresponding to the plurality of recesses 72 .
- the embodiment shown in FIG. 57 is illustrative of a structure in which the recess 72 has a circular contour, and the detecting piezoelectric/electrostrictive element 12 has a circular planar configuration.
- a vibration gyro sensor according to a forty-fourth embodiment shown in FIG. 58 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-third embodiment shown in FIG. 57.
- the former is different from the latter in that thick-walled block sections 70 are provided in an integrated manner between the first plate-shaped sections 6 and the second plate-shaped sections 8 respectively.
- the presence of the block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shaped section 6 and the second plate-shaped section 8 . Moreover, a large output can be obtained. Accordingly, this embodiment is advantageous in view of high reliability and improvement in sensitivity.
- the vibration gyro sensors according to the forty-third and forty-fourth embodiments described above are illustrative of the structure in which the detecting piezoelectric/electrostrictive elements 12 each having the approximately circular planar configuration are formed in the array of islands on the upper surface of the first plate-shaped section 6 .
- both of the contour of each of the recesses 72 (see FIG. 48) and the detecting piezoelectric/electrostrictive elements 12 may be square or rectangular (forty-fifth and forty-sixth embodiments).
- planar configuration of the recess 72 and the detecting piezoelectric/electrostrictive element 72 also include, for example, circular and rectangular configurations as described above, as well as rhombic configurations.
- the shape of these components is not specifically limited.
- the driving means 122 which has the driving section (third plate-shaped section) 10 with the driving piezoelectric/electrostrictive element 14 formed on its upper surface, is provided in the integrated manner between the second plate-shaped sections 8 .
- a mechanism wherein a signal, which is obtained from a reference means 140 disposed at a position different from that of the driving section 10 , is fed to the driving means 122 in a feedback manner in order to maintain constant vibration of the vibrators 2 .
- a vibration gyro sensor according to a forty-seventh embodiment shown in FIG. 61 has such a structure that the vibration gyro sensor according to the thirty-fourth embodiment (see FIG. 46) further comprises the reference means 140 which is provided in parallel to the driving means 122 between the two second plate-shaped sections 8 .
- the reference means 140 is constructed in approximately the same manner as the driving means 122 , comprising a plate-shaped reference section (fourth plate-shaped section) 144 which is thin-walled in its direction of height, and a reference piezoelectric/electrostrictive element 142 formed on the reference section 144 .
- the reference section 144 is integrally formed of ceramics in the same manner as the driving section 10 .
- the reference section 144 and the driving section 10 are arranged in accordance with the following relation. Namely, the driving section 10 is formed in an integrated manner at a position close to the frame 80 between the second plate-shaped sections 8 .
- the reference section 144 is formed in an integrated manner at a position slightly nearer to the first plate-shaped sections 6 as compared with the driving section 10 .
- the signal which is obtained from the reference piezoelectric/electrostrictive element 142 of the reference means 140 , is fed to the driving piezoelectric/electrostrictive element 14 in the feedback manner to give constant vibration of the driving means 122 formed between the second plate-shaped sections 8 .
- the driving signal is supplied to the driving means 122 via lead wires 200 a, 200 b connected to upper and lower electrodes (not shown) formed on upper and lower surfaces of the driving piezoelectric/electrostrictive element 14 .
- the reference signal is obtained from the reference means 140 via lead wires 202 a, 202 b connected to upper and lower electrodes (not shown) formed on upper and lower surfaces of the reference piezoelectric/electrostrictive element 142 .
- the detection signal is obtained from the detecting piezoelectric/electrostrictive element 12 formed on the first plate-shaped section 6 via lead wires 204 a, 204 b connected to upper and lower electrodes (not shown) formed on upper and lower surfaces of the detecting piezoelectric/electrostrictive element 12 .
- a vibration gyro sensor according to a forty-eighth embodiment shown in FIG. 63 has such a structure that the vibration gyro sensor according to the thirty-sixth embodiment shown in FIG. 49 further comprises a reference means 140 which is provided in parallel to the driving means 122 between the two second plate-shaped sections 8 .
- This embodiment is constructed as follows as shown in FIG. 64. Namely, the respective upper electrodes of the plurality of detecting piezoelectric/electrostrictive elements 12 formed in the array of islands are electrically connected to lead wires 204 a via mediating conductors 206 a respectively. The respective lower electrodes of the plurality of detecting piezoelectric/electrostrictive elements 12 are electrically connected to lead wires 204 b via mediating conductors 206 b respectively. The detection signal is obtained from the detecting piezoelectric/electrostrictive elements 12 via the lead wires 204 a, 204 b.
- a vibration gyro sensor according to a forty-ninth embodiment shown in FIG. 65 is constructed as follows, based on the vibration gyro sensor according to the thirty-ninth embodiment (see FIG. 52). Namely, a mediating section (sixth plate-shaped section) 208 having a free end is provided in an integrated manner at an approximately central portion of a side surface of the support base 4 facing to the vibrators 2 . A driving means 122 is provided in an integrated manner between the mediating section 208 and one of the second plate-shaped sections 8 . A reference means 140 as described above is provided in an integrated manner between the mediating section 208 and the other second plate-shaped section 8 .
- the support section 76 (fifth plate-shaped section) is formed between the support base 4 and the attachment section 74 so that the support section 76 is disposed at a position which is approximately coincides with the position of line symmetry of the tuning fork 78 . Accordingly, when one of the two second plate-shaped sections 8 is vibrated to vibrate the corresponding vibrator 2 , the other vibrator 2 is vibrated at an identical frequency.
- a vibration gyro sensor according to a fiftieth embodiment shown in FIG. 66 is constructed as follows, based on the vibration gyro sensor according to the thirty-ninth embodiment (see FIG. 52). Namely, a plurality of mediating sections 210 a, 210 b having respective free ends are provided in an integrated manner at positions of both ends in the longitudinal direction on a side surface of the support base 4 facing to the vibrators 2 .
- a driving means 122 is provided in an integrated manner between one of the second plate-shaped sections 8 and one of the mediating sections 210 a.
- a reference means 140 is provided in an integrated manner between the other second plate-shaped section 8 and the other mediating section 210 b.
- the vibration gyro sensors according to the forty-ninth and fiftieth embodiments have the structure in which the tuning fork 78 is provided in the integrated manner on the block-shaped attachment section 74 .
- the attachment section 74 is provided as a rectangular frame (attachment frame) 80 , as exemplified by vibration gyro sensors according to fifty-first and fifty-second embodiments shown in FIGS. 67 and 68.
- the reference means 140 may be used to perform feedback control so that the vibration effected by the driving means 122 is constant. Further, these embodiments are advantageous from viewpoints of, for example, the degree of freedom for attachment and rigidity, because the attachment section is provided as the attachment frame 80 .
- a vibration gyro sensor according to a fifty-third embodiment shown in FIG. 69 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-second embodiment shown in FIG. 56.
- the former is different from the latter in that the support section 76 is constructed as follows.
- the support section 76 comprises a first support section 212 provided in an integrated and bridged manner to bridge a pair of inner wall surfaces of inner wall surfaces of the attachment frame 80 along the extending direction of the vibrators 2 so that the vibrators 2 are disposed thereover as shown in FIGS. 70A and 70C, and a second support section 214 provided in an integrated and bridged manner to bridge the first support section 212 and the support base 4 so that the driving means 122 is disposed thereover as shown in FIG. 70B.
- the vibration gyro sensor according to the forty-second embodiment has the structure in which the support section 76 constructed by the fifth plate-shaped section is provided in the integrated manner between the support base 4 and the attachment frame 80 . Therefore, if the support section 76 is elongated, the entire length of the sensor is also elongated in accordance therewith. Accordingly, the elongation of the support section 76 is limited.
- the second support section 214 which functions in substantially the same manner as the support rod for the tuning fork 78 , is provided in parallel to the two second plate-shaped sections 8 , giving the structure in which the second support section 214 extends in the same direction as the second plate-shaped sections 8 . Therefore, even when the length of the second support section 214 is elongated, the entire length of the sensor is not changed until the length of the second support section 214 exceeds a certain range. Accordingly, the second support section 214 can be elongated, and it is possible to realize further improvement in detection accuracy.
- first and second support sections 212 , 214 can be also applied, for example, to vibration gyro sensors each including the driving means 122 and the reference means 140 as shown in FIGS. 71 and 72.
- the vibration gyro sensor according to a fifty-fourth embodiment shown in FIG. 71 is constructed such that the first and second support sections 212 , 214 are provided in place of the support section 76 of the vibration gyro sensor according to the fifty-first embodiment shown in FIG. 67.
- the vibration gyro sensor according to a fifty-fifth embodiment shown in FIG. 72 is constructed such that the first and second support sections 212 , 214 are provided in place of the support section 76 of the vibration gyro sensor according to the fifty-second embodiment shown in FIG. 68.
- the vibration gyro sensor constructed by the integrated fired product made of ceramics can be formed as the integrated stacked structure comprising the thin plate layer 22 , the substrate layer 24 , and the spacer layer 26 as shown in FIG. 2.
- the vibration gyro sensor can be constructed by using an additional layer (intermediate layer) 216 which is allowed to intervene between the thin plate layer 22 and the substrate layer 24 .
- the thickness of the intermediate layer 216 is appropriately 1 ⁇ m to 500 ⁇ m, preferably 10 ⁇ m to 400 ⁇ m, and more preferably 50 ⁇ m to 300 ⁇ m. If the thickness exceeds 500 ⁇ m, it is difficult to make bending, and hence the sensitivity is lowered. If the thickness is thinner than 1 ⁇ m, the strength is low, and hence a problem arises in that the intermediate layer 216 tends to suffer breakage. Accordingly, it is preferable to adopt the foregoing range for the thickness of the intermediate layer 216 .
- the formation of the intermediate layer 216 is preferred in order to ensure the strength and improve the sensitivity, concerning the vibration gyro sensors of the type in which the block-shaped vibrators 2 are supported by the thin-walled first plate-shaped sections 6 (see FIGS. 1, 4 to 18 , and 38 to 41 ), and concerning the vibration gyro sensors of the type in which the support base 100 integrally provided with the four block-shaped vibrators 102 A to 102 D is supported by the thin-walled plate-shaped sections 116 (see FIGS. 22 and 24 to 37 ).
- the intervention of the intermediate layer 216 is also advantageous in order to ensure the strength and improve the sensitivity for those of the type in which the vibrator 2 is constructed by the thin-walled first plate-shaped section 6 , as in the vibration gyro sensors according to the thirty-first to fifty-fifth embodiments shown in FIGS. 42 to 72 . Examples of such construction are shown in FIGS. 74 to 76 .
- FIG. 74 An embodiment shown in FIG. 74 is illustrative of a structure in which the intermediate layer 216 is allowed to intervene between the thin plate layer 22 and the substrate layer 24 for constructing the vibration gyro sensor according to the thirty-third embodiment shown in FIG. 45.
- An upper surface portion 32 a of the frame 32 , upper portions 6 a of the first plate-shaped sections 6 , upper end portions 8 a of the second plate-shaped sections 8 , and the third plate-shaped section 10 are formed in an integrated manner by processing the thin plate layer 22 .
- An upper portion 32 b of the frame 32 except for the upper surface portion thereof, lower portions 6 b of the first plate-shaped sections 6 , and upper portions 8 b of the second plate-shaped sections 8 except for the upper end portions thereof are formed in an integrated manner by processing the intermediate layer 216 .
- a remaining portion 32 c of the frame 32 and remaining portions 8 c of the second plate-shaped sections 8 are formed in an integrated manner by processing the substrate layer 24 .
- the layers are stacked and integrated with each other, followed by firing.
- FIG. 75 An embodiment shown in FIG. 75 is illustrative of a structure in which the intermediate layer 216 is allowed to intervene between the thin plate layer 22 and the substrate layer 24 for constructing the vibration gyro sensor according to the thirty-fourth embodiment shown in FIG. 46.
- An upper surface portion 32 a of the frame 32 , upper portions 6 a of the first plate-shaped sections 6 , upper end portions 8 a of the second plate-shaped sections 8 , and the third plate-shaped section 10 are formed in an integrated manner by processing the thin plate layer 22 .
- An upper portion 32 b of the frame 32 except for the upper surface portion thereof, lower portions 6 b of the first plate-shaped sections 6 , and upper portions 8 b of the second plate-shaped sections 8 except for the upper end portions thereof are formed in an integrated manner by processing the intermediate layer 216 .
- a remaining portion 32 c of the frame 32 , remaining portions 8 c of the second plate-shaped sections 8 , and the block sections 70 are formed in an integrated manner by processing the substrate layer 24 .
- the layers are stacked and integrated with each other, followed by firing. Thus the vibration gyro sensor according to the thirty-fourth embodiment is produced.
- FIG. 76 An embodiment shown in FIG. 76 is illustrative of a structure in which the intermediate layer 216 is allowed to intervene between the thin plate layer 22 and the substrate layer 24 for constructing the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47.
- An upper surface portion 32 a of the frame 32 , upper portions 6 a of the first plate-shaped sections 6 , upper end portions 8 a of the second plate-shaped sections 8 , and the third plate-shaped section 10 are formed in an integrated manner by processing the thin plate layer 22 .
- the vibrators 2 (or 102 ), the support base 4 (or 100 ), the attachment frame 30 , 36 , 38 , the frame 32 (or 104 ), and other components are constructed as a whole by the integrated fired product made of ceramics (non-conductive substances) represented by zirconia oxide. Accordingly, the present invention is advantageous in that external wiring can be directly wired and formed thereon by means of the film formation method.
- the film formation method such as screen printing is used to form the electrodes of the piezoelectric/electrostrictive elements 12 , 14 , 118 , 120 , 142 .
- the present invention is also advantageous in that when the electrodes of the piezoelectric/electrostrictive elements 12 , 14 , 118 , 120 , 142 are formed, the wiring for these electrodes can be simultaneously extended up to the frame section (frame 104 ) so that the vibration characteristics are not affected. Therefore, it is possible to realize improvement in yield and easy production of the vibration gyro sensor.
- the thin-walled second plate-shaped sections 8 are depicted as those having the planar plate configuration in any case.
- the present invention is not limited to those having the planar plate configuration. It is allowable to use a structure in which the rigidity is lowered in order to easily vibrate the vibrators in their desired vibration directions. It is needless to say that no problem occurs at all when those having a partially constricted shape are used.
- the vibration gyro sensor according to the present invention is constructed as a whole by the integrated fired product made of ceramics, and no magnetic material is used at all. Therefore, it is completely unnecessary to consider any influence exerted on the characteristics by the ambient magnetic field, and the vibration gyro sensor does not undergo any restriction concerning its installation place or the like. Further, the large displacement is obtained by using the first and second plate-shaped sections in the detecting and driving directions of the vibrators. Moreover, the vibration gyro sensor has the integrated structure in which the piezoelectric/electrostrictive element directly contacts with the vibrator. Accordingly, the large output is effectively obtained, and any cause to lower the sensitivity due to absorption of stress is effectively dissolved. Thus the highly sensitive sensor is advantageously provided.
- the combined sensor according to the present invention is different from the conventional sensor which has only one function for one element.
- the combined sensor makes it extremely easy to provide another sensor in the integrated manner adjacent to the vibration gyro sensor. For example, it is possible to easily realize the structure in which the vibration gyro sensor and the acceleration sensor are simultaneously provided as one element (integrated sensor).
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Abstract
A vibration gyro sensor is constructed as follows. Namely, a detecting piezoelectric/electrostrictive element 12, which detects displacement generated in a direction perpendicular to a direction of vibration of a vibrator 2 when the vibrator is rotated, is provided on a detecting section. The detecting section is constructed by an integrated fired product made of ceramics together with the vibrator 2 and a support base 4. The detecting section is constructed by a first plate-shaped section 6 which is more thin-walled than the vibrator 2 and which has its principal surface extending in the direction of vibration. The piezoelectric/electrostrictive element 12 is formed in an integrated manner on the first plate-shaped section 6 in accordance with a film formation method. Further, a thin-walled second plate-shaped section 8, which is provided for decreasing rigidity in the direction of vibration and facilitating the vibration for the vibrator 2, is formed in an integrated manner so that its principal surface extends in the direction perpendicular to the direction of vibration. Accordingly, it is possible to obtain the vibration gyro sensor made of ceramics having excellent sensitivity, in which the characteristics of the vibrator are scarcely affected by an ambient magnetic field, processing or machining can be easily performed, and the electric characteristics can be advantageously adjusted.
Description
- The present invention relates to a vibration gyro sensor. In particular, the present invention relates to a vibration gyro sensor (scope) for detecting the angular velocity of rotation by utilizing the Coriolis force generated when a vibrator is rotated while making vibration, and a method for producing the vibration gyro sensor. The present invention also relates to a combined sensor including the vibration gyro sensor.
- The gyro sensor (scope), which is a sensor for detecting the angular velocity of rotation, has been hitherto used, for example, for inertial navigation systems of aircraft and shipping. Recently, the gyro sensor is used for vehicle-carried navigation systems and for attitude control systems of automatically guided robot vehicles. Further, the gyro sensor is also used, for example, for picture blurring-preventive systems of VTR cameras. In such circumstances, a compact type gyro sensor is required, which is appropriately used in various fields as described above. Accordingly, the vibration gyro sensor attracts attention.
- As well-known, the vibration gyro sensor (scope) of this type has a basic structure comprising a driving piezoelectric element and a detecting piezoelectric element which adhere to a vibrator formed of a constant resilience metal represented by the elinvar alloy. In a rectangular coordinate system of x, y, z axes, when the vibrator is rotated about the z axis while giving bending vibration in the x axis direction to the vibrator by using the driving piezoelectric element, the Coriolis force acts in the y axis direction to the vibrator. Accordingly, the bending vibration in the y axis direction caused in the vibrator by the Coriolis force is detected as a voltage by the aid of the detecting piezoelectric element. The angular velocity is determined on the basis of the detected voltage.
- However, in the case of the conventional vibration gyro sensor as described above, the amount of displacement of the vibrator, which is based on the vibration induced by the driving piezoelectric element, is small. Therefore, the voltage (electromotive force), which is detected by the detecting piezoelectric element, is small. As a result, the conventional vibration gyro sensor involves a problem that the sensitivity is low.
- In addition, the driving piezoelectric element and the detecting piezoelectric element are glued and fixed to the vibrator by using an adhesive. Therefore, the adhesive intervenes between the vibrator and the piezoelectric elements. As a result, the stress is absorbed by the adhesive. Due to this fact, together with other factors, if any, a problem arises in that the detection sensitivity is lowered.
- When the vibrator comprises a member which is composed of a sound chip or a tuning fork formed of an elinvar alloy, a problem arises in that the characteristics of the vibrator tend to be affected by an ambient magnetic field, because the elinvar alloy is a ferromagnetic material. Further, due to the shape or the material of the vibrator as described above, there is an implicit problem that it is difficult to perform processing or machining when the resonance frequency of the vibrator is adjusted.
- The present invention has been made on the background of such circumstances, an object of which is to solve all problems as described above and provide a vibration gyro sensor having excellent sensitivity. Another object of the present invention is to provide a vibration gyro sensor made of ceramics, in which the characteristics of the vibrator are scarcely affected by an ambient magnetic field, processing or machining can be easily performed, and the electric characteristics can be advantageously adjusted.
- The present invention provides a vibration gyro sensor which is constructed as a whole by an integrated fired product made of ceramics without using any magnetic material. Therefore, the vibration gyro sensor according to the present invention scarcely affected by any ambient magnetic field. Further, the vibration gyro sensor includes first plate-shaped sections and second plate-shaped sections which are thin-walled respectively and which are provided as easily bendable sections in driving and detecting directions for making displacement of vibrators respectively. Therefore, large displacement is obtained in any of the detecting and driving directions, thus giving a large electromotive force (voltage) generated depending on the displacement detected by piezoelectric/electrostrictive elements, and making it possible to effectively increase the detection sensitivity. Especially, the detecting section has a structure to which the stress is concentrated. Therefore, a large output is obtained.
- Moreover, the vibration gyro sensor according to the present invention includes the detecting piezoelectric/electrostrictive elements which are formed in an integrated manner in accordance with a film formation method on the first plate-shaped sections for giving the detecting sections constructed by the integrated fired product made of ceramics. The piezoelectric/electrostrictive elements directly contact with the first plate-shaped sections without any intervening adhesive layer. Therefore, any absorption of stress, which would be otherwise caused due to the presence of such an adhesive layer, is effectively avoided. Accordingly, the displacement (bending vibration) of the vibrators, which is caused by the Coriolis force induced when the vibrators are rotated, can be effectively detected by the piezoelectric/electrostrictive elements, making it possible to advantageously contribute to the improvement in sensitivity.
- In the vibration gyro sensor according to the present invention, for example, the electrode area of the piezoelectric/electrostrictive element provided on the detecting section can be easily changed by using an appropriate removing means such as a laser. Therefore, the vibration gyro sensor also has such a feature that its electric characteristics are easily adjusted.
- In a preferred embodiment of the present invention, the vibrator is provided with a thin-walled excisable section extending from a forward end of the vibrator, and a resonance frequency of the vibrator is adjusted in accordance with an amount of excision of the excisable section. The thin-walled excisable section, which is provided at the end of the vibrator, is an easily processible or machinable portion. The resonance frequency of the vibrator can be easily adjusted to have a desired value by providing such an excisable section for trimming beforehand, and excising the excisable section by means of an appropriate excising means such as laser machining and ultrasonic machining.
- In another preferred embodiment of the present invention constructed as described above, two of the vibrators are supported in parallel to one another by the support base, and the two vibrators are vibrated by the driving means in an excited manner in mutually opposite directions. In this embodiment, the vibration gyro sensor may be constructed such that the driving means comprises a third plate-shaped section which is more thin-walled than the vibrator and which is composed of the integrated fired product of ceramics together with the vibrator, and a driving piezoelectric/electrostrictive element formed in an integrated manner on the third plate-shaped section in accordance with the film formation method.
- In still another preferred embodiment of the present invention constructed as described above, a support bar is arranged at a position which is located between the two vibrators and which is separated from the vibrators, and the support bar is supported in an integrated manner by the support base together with the two vibrators.
- In still another preferred embodiment of the present invention constructed as described above, the support base is constructed by an attachment frame which is disposed outside the vibrator and separated therefrom by a predetermined distance so that the vibrator is surrounded thereby. Provision of the attachment frame makes it, possible to tightly fix the vibration gyro sensor, exhibiting a feature that a place for installing the vibration gyro sensor can be selected with a large degree of freedom.
- The following embodiments may be adopted for the position of arrangement of the driving means. Namely, the driving means may be provided in an integrated manner between the two vibrators. Alternatively, the driving means may be provided in an integrated manner between the second plate-shaped sections.
- When the vibration gyro sensor includes the support bar, the driving means may be provided in an integrated manner between the support bar and the vibrators respectively, or the driving means may be provided in an integrated manner between the support bar and the second plate-shaped sections respectively.
- When the vibration gyro sensor includes the attachment frame, the driving means may be provided in an integrated manner between the attachment frame and the vibrators respectively, or the driving means may be provided in an integrated manner between the attachment frame and the second plate-shaped sections respectively.
- According to another aspect, there is provided a second type of the vibration gyro sensor according to the present invention, wherein a second plate-shaped section and a third plate-shaped section are provided in an integrated manner at opposing regions on a frame for supporting two vibrators, and a driving piezoelectric/electrostrictive element is formed in an integrated manner on the third plate-shaped section so that the two vibrators may be vibrated in an excited manner in accordance with deformation vibration of the frame effected by the driving piezoelectric/electrostrictive element.
- The vibration gyro sensor, which makes the deformation vibration of the frame as described above, advantageously adopts a structure in which an attachment section for fixing the frame is formed in an integrated manner on an outer surface of a region of the frame for forming the second plate-shaped section, in order to facilitate fixation of the frame. Alternatively, a structure is advantageously adopted, in which the attachment section includes, in an integrated manner, an attachment frame which is positioned outside the frame and separated therefrom by a predetermined distance so that the frame is surrounded thereby. Such an attachment frame realizes tight fixation of the vibration gyro sensor.
- According to still another aspect, there is provided a third type of the vibration gyro sensor according to the present invention, which is different from the vibration gyro sensors of the foregoing two types. Namely, support base portions for supporting two vibrators respectively are individually subjected to deformation vibration respectively by the aid of driving piezoelectric/electrostrictive elements provided on third plate-shaped sections for making connection to an attachment frame disposed outside. Accordingly, the two vibrators, which are supported by the respective support base portions, are individually vibrated in an identical plane respectively.
- The vibration gyro sensor of the third type is also advantageously constructed such that each of the vibrators has a thin-walled excisable section extending from a forward end thereof, in the same manner as the vibration gyro sensor of the second type. The resonance frequency of the vibrator is adjusted in accordance with the amount of excision of the excisable section. Accordingly, trimming can be easily performed by means of an excising means such as laser machining and ultrasonic machining. Thus it is possible to easily adjust the resonance frequency.
- According to still another aspect, there is provided a fourth type of the vibration gyro sensor according to the present invention. At first, when an angular velocity is applied around an axis perpendicular to a plane which includes a certain direction and an extending direction of the support base in a state of vibration of the vibrators, the force (Coriolis force) directed in the certain direction is generated in an alternating manner in the vibrators in accordance with the vibration. As a result, a force acts on the detecting sections in the certain direction, and the detecting sections are vibrated by the force. Namely, rotational vibration is generated around the axis of rotation at portions comprising the vibrators and the support base. The generated vibration is detected as an electromotive force (voltage) by the piezoelectric/electrostrictive elements of the detecting sections.
- According to the present invention, all of the vibrators, the support base, and the detecting sections are. constructed by an integrated fired product made of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. As a result, the characteristics of the sensor are not affected by any ambient magnetic field.
- The detecting section is constructed by the first plate-shaped section which is more thin-walled than the vibrator in its direction of height, and thus it has the structure having low rigidity. Therefore, large strain or distortion is obtained in the detecting section when the vibration is generated around the axis of rotation by the angular velocity, and thus the detection sensitivity of the piezoelectric/electrostrictive element is greatly improved.
- Especially, the vibration gyro sensor according to the present invention functions such that the vibration is generated in the detecting section only when the angular velocity is applied. Therefore, the output (null voltage), which is obtained from the piezoelectric/electrostrictive element in a state in which no angular velocity is applied, is extremely small. Thus the detection sensitivity is greatly improved. Moreover, the probability of occurrence of fatigue fracture at the detecting section due to vibration is lowered, and it is possible to contemplate a long service life of the sensor.
- The vibration gyro sensor according to the present invention has the structure not for measuring the angular velocity around the major axis of the vibrator, but for measuring the angular velocity around the axis perpendicular to the plane which includes the certain direction and the extending direction of the support base. Therefore, the vibrators, the support base, and the frame can be made thin in their direction of height. Thus it is possible to facilitate realization of a compact size and a light weight of the sensor.
- The vibrator has the structure including no thin-walled detecting section and supported singly by the support base which has high strength. Therefore, the vibrator itself is allowed to have a large mass. Accordingly, the Coriolis force (Fc=2 mv Ω) generated in the vibrator is increased, and hence it is possible to realize a high sensitivity in relation to the detection of strain effected by the detecting section.
- It is preferable for the vibration gyro sensor according to the present invention that each of the detecting sections is constructed by a ring member formed between the support base and the frame, and the first plate-shaped section provided in a bridged manner in the ring member in parallel to the extending direction of the support base.
- In this embodiment, when the angular velocity is applied around the axis perpendicular to the plane which includes the certain direction and the extending direction of the support base in a state in which the vibrator is rotated, the force acts in the certain direction on the detecting section. The action of the force allows the ring member to make vibration while giving an elliptic configuration having its major or minor axis directed in the certain direction. The vibration of the ring member along the certain direction is detected as an electromotive force (voltage) by the piezoelectric/electrostrictive element.
- It is preferable for the vibration gyro sensor according to the present invention that at least two of the vibrators are supported by the support base in parallel to one another, and a driving means for vibrating the respective vibrators in an excited manner in mutually opposite directions is disposed between the two vibrators. In this embodiment, the at least two vibrators make excited vibration in the mutually opposite directions, namely in directions to make mutual separation and approach in one plane (in the plane which includes the certain direction and the extending direction of the support base). It is preferable that the driving means includes, for example, a third plate-shaped section which is more thin-walled in its direction of height than the vibrator and which is constructed by the integrated fired product of ceramics together with the vibrator, and a driving piezoelectric/electrostrictive element formed on the third plate-shaped section.
- It is preferable for the vibration gyro sensor constructed as described above that the driving means is provided in an integrated manner between the two vibrators. Especially preferably, the driving means is arranged on a line for connecting respective centers of gravity of the both vibrators. This arrangement is advantageous to improve the sensitivity of the detecting section, since the at least two vibrators can make mutual approach and separation efficiently. Alternatively, the driving means may be provided in an integrated manner between the respective vibrators and the support base.
- It is preferable that the vibration gyro sensor constructed as described above further comprises a reference means for performing feedback control so that the vibration of the driving means is constant. The reference means may comprise a fourth plate-shaped section which is more thin-walled in its direction of height than the vibrator and which is constructed by the integrated fired product made of ceramics together with the vibrator, and a reference piezoelectric/electrostrictive element formed on the fourth plate-shaped section.
- The reference means may be provided in an integrated manner between the respective vibrators. Alternatively, the reference means may be provided in an integrated manner between the respective vibrators and the support base.
- It is preferable that the vibration gyro sensor constructed as described above further comprises vibration-applying sections provided in an integrated manner between the respective vibrators and the support base. The vibration-applying section may comprise a fifth plate-shaped section arranged between the vibrator and the support base and extending in parallel to a longitudinal direction of the support base, a sixth plate-shaped sections for connecting the support base to the fifth plate-shaped section, and a seventh plate-shaped section for connecting the vibrator to the fifth plate-shaped section. In this embodiment, the driving means may be provided in an integrated manner between the respective vibration-applying sections. Alternatively, the driving means may be provided in an integrated manner between each of the vibration-applying sections and the support base.
- It is preferable that the vibration gyro sensor constructed as described above further comprises thin-walled first projections for adjusting a resonance frequency for driving, provided at free ends of the vibrators, and thin-walled second projections for adjusting a resonance frequency for detection, provided at both ends of the support base in its longitudinal direction, wherein the first and second projections are constructed by the integrated fired product made of ceramics together with the vibrators and the support base.
- In this embodiment, the resonance frequency for driving can be adjusted by applying a trimming treatment (excising treatment) to the first projection, and the resonance frequency for detection can be adjusted by applying a trimming treatment (excising treatment) to the second projection. Namely, the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving. When the resonance frequency is adjusted, it is preferable that the resonance frequency for driving is firstly adjusted, and then the resonance frequency for detection is adjusted.
- For example, the first and second projections may be constructed to be plate-shaped and thin-walled in a direction of height with respect to the vibrators. Alternatively, the first and second projections may be constructed to be plate-shaped and thin-walled in the extending direction of the support base with respect to the vibrators. The former construction is advantageous in that the trimming treatment can be easily performed by means of, for example, laser beam scanning over the upper surface. In the case of the latter construction, regions to be subjected to the trimming treatment are disposed over entire surfaces perpendicular to the direction of vibration of the vibrators, and hence an extremely excellent mass balance is obtained. In this case, the trimming treatment is performed, for example, by applying percussion such as ultrasonic waves after laser radiation so that unnecessary portions are excised.
- It is preferable for the vibration gyro sensor constructed as described above that the third plate-shaped section of the driving means is also used as an adjustment objective for a resonance frequency for driving, and the first plate-shaped section of the detecting section is also used as an adjustment objective for a resonance frequency for detection. Specifically, the resonance frequency for driving is adjusted by trimming-treating, in the widthwise direction, the third plate-shaped section of the driving means, and the resonance frequency for detection is adjusted by trimming-treating, in the widthwise direction, the first plate-shaped section of the detecting section. Namely, this embodiment lies in the method in which the resonance frequencies for driving and detection are adjusted by changing spring constants of the first and third plate-shaped sections, rather than that the resonance frequencies for driving and detection are adjusted by changing masses of the vibrator and the support base.
- In this embodiment, it is unnecessary to form the first and second projections at the free ends of the vibrators and at the both ends of the support base in the longitudinal direction respectively. Accordingly, the production steps can be simplified. Further, since the regions to be subjected to the trimming treatment are thin-walled, the resonance frequency can be easily adjusted. Unlike the method in which the resonance frequency is adjusted by changing the mass, the resonance frequency for driving and the resonance frequency for detection can be adjusted completely independently.
- According to still another aspect, there is provided a fifth type of the vibration gyro sensor according to the present invention, wherein vibrators are constructed by wide and lengthy first plate-shaped sections respectively. Accordingly, the mass and the moment of the vibrator are increased. As a result, the velocity (∝ amplitude) brought about by the driving vibration is increased. Therefore, it is possible to further improve the sensitivity.
- It is preferable that the detecting piezoelectric/electrostrictive element is formed in an integrated manner on an approximately entire surface of the first plate-shaped section. This embodiment is advantageous in the case of the current-detecting system, because it is possible to accumulate a large amount of electric charge.
- It is preferable for the vibration gyro sensor constructed as described above that the first plate-shaped section has, on its back surface, a plurality of recesses, and the detecting piezoelectric/electrostrictive elements as defined above are formed in an array of islands at positions on a front surface of the first plate-shaped section corresponding to the plurality of recesses. In this embodiment, the strength is decreased at the portions of the first plate-shaped section at which the recesses are formed. Therefore, when the first plate-shaped section is deformed by the Coriolis force, large strain is generated at the portions at which the recesses are formed as compared with other portions at which no recess is formed. Accordingly, when the detecting piezoelectric/electrostrictive elements are formed on the portions corresponding to the recesses, a large detection output can be obtained, and the sensitivity can be further improved.
- It is preferable for the vibration gyro sensor constructed as described above that a thick-walled block section is provided in an integrated manner between the first plate-shaped section and the second plate-shaped section. In this embodiment, owing to the presence of the block section, it is possible to increase the strength of the boundary portion, which is advantageous from a viewpoint of improvement in reliability.
- The support base may be constructed by a frame which is positioned outside the vibrators and separated by predetermined distances so that the vibrators are surrounded thereby. When the support base has the form of frame, it is possible to obtain a large degree of freedom for attachment, and the rigidity is excellent. Therefore, this embodiment is preferred from a practical viewpoint.
- The driving means may be provided in an integrated manner between the respective second plate-shaped sections. Alternatively, the driving means may be provided in an integrated manner between the respective block sections. Further alternatively, the driving means may be provided in an integrated manner between the block section and the frame.
- It is preferable that the vibration gyro sensor constructed as described above further comprises a reference means for performing feedback control so that the vibration of the driving means is constant. The reference means may be provided in an integrated manner between the respective second plate-shaped sections.
- In still another embodiment, the driving means may be provided in an integrated manner on one plate-shaped section of the respective second plate-shaped sections, and the reference means may be provided on the other plate-shaped section.
- In this embodiment, it is possible to adopt a structure in which a mediating section having a free end is provided in an integrated manner at an approximately central portion of a side surface of the support base facing to the vibrating section, the driving means is provided in an integrated manner between one of the second plate-shaped sections and the mediating section, and the reference means is provided in an integrated manner between the other second plate-shaped section and the mediating section.
- It is also possible to adopt a structure in which a plurality of mediating sections each having a free end are provided in an integrated manner at positions of both ends in a widthwise direction of the support base facing to the vibrating sections, the driving means is provided in an integrated manner between one of the second plate-shaped sections and one of the mediating sections, and the reference means is provided in an integrated manner between the other second plate-shaped section and the other mediating section.
- It is preferable for the vibration gyro sensor constructed as described above that an attachment section for fixing the support base is provided in an integrated manner on a surface opposite to a surface of the support base on which the second plate-shaped sections are formed, a fifth plate-shaped section, which is thin-walled in a widthwise direction of the support base, is provided in an integrated manner between the support base and the attachment section, and a tuning fork is constructed by at least the support base and the vibrators. In this embodiment, the fifth plate-shaped section functions as a support rod for supporting the tuning fork. Therefore, it is easy to discriminate necessary modes for the vibration gyro sensor from unnecessary modes, and it is possible to improve the detection accuracy.
- It is preferable for the vibration gyro sensor constructed as described above that the attachment section is constructed by an attachment frame which is positioned outside the tuning fork and separated by predetermined distances therefrom so that the tuning fork is surrounded thereby. In this embodiment, it is possible to improve the detection accuracy. Further, this embodiment is preferred, for example, from viewpoints of the degree of freedom for attachment and rigidity, because the attachment section is provided as the attachment frame.
- In the embodiment provided with the attachment frame as described above, it is possible to adopt a structure in which a support section is provided in an integrated and bridged manner so that a pair of inner wall surfaces of the attachment frame, which extend along the extending direction of the vibrators, are bridged by the support section facing to the vibrators disposed thereover, and the fifth plate-shaped section is provided in an integrated manner between the support section and the support base.
- In this embodiment, even when the length of the fifth plate-shaped section is elongated, the entire length of the sensor is not changed until within a certain range. Therefore, it is possible to elongate the fifth plate-shaped section, and it is possible to realize further improvement in detection accuracy.
- In still another aspect, the present invention makes it possible to advantageously construct and realize a combined sensor by using those provided with the attachment frame, of the vibration gyro sensors described above, wherein a second attachment frame integrated with the attachment frame is provided adjacent to the attachment frame, and another sensor having a function different from that of the vibration gyro sensor is supported in an integrated manner in the second attachment frame.
- Especially, the conventional vibration gyro sensor merely realizes an element having only one function. However, when an additional sensor having another function is provided by utilizing the attachment frame as described above, it is possible to easily provide a combined sensor or an integrated sensor which not only functions as the vibration gyro sensor, but also simultaneously realizes another function.
- In still another aspect, the present invention lies in a method for producing a vibration gyro sensor, comprising the steps of stacking and integrating at least a substrate layer and a thin plate layer composed of green sheets, followed by firing to produce a fired product including, in an integrated manner, at least one or more vibrators each having a major axis extending in a certain direction, a support base extending in a direction perpendicular to the certain direction, for supporting the vibrator at one end, a frame having its frame surface parallel to a plane which includes the certain direction and the extending direction of the support base, for surrounding the vibrator and the support base, and at least one or more detecting sections attached between the support base and the frame; forming at least one or more piezoelectric/electrostrictive elements on at least the detecting sections in accordance with a film formation method; adjusting a resonance frequency for driving by applying a trimming treatment to a part of the vibrator; and adjusting a resonance frequency for detection by applying a trimming treatment to a part of the support base.
- According to this method, it is possible to easily and highly reliably produce the vibration gyro sensor having the structure in which the support base and the vibrators are surrounded by the frame, and the support base is connected to the frame via the detecting sections. The resonance frequencies for driving and detection can be easily adjusted by trimming-treating a part of the vibrators and a part of the support base respectively. Therefore, this method is advantageous to reduce the number of production steps.
- It is preferable to use, as the vibration gyro sensor, a vibration gyro sensor comprising at least two of the vibrators supported in parallel to one another by the support base, and a driving means provided between the two vibrators for vibrating the respective vibrators in an excited manner in mutually opposite directions, wherein the driving means includes a third plate-shaped section which is more thin-walled in its direction of height than the vibrators and which is composed of the integrated fired product made of ceramics together with the vibrators, and a driving piezoelectric/electrostrictive element formed on the third plate-shaped section.
- It is preferable that the adjustment for the resonance frequency for driving is performed by applying a trimming treatment to a thin-walled first projection protruding in an integrated manner from a free end of the vibrator, and the adjustment for the resonance frequency for detection is performed by applying a trimming treatment to thin-walled second projections protruding in an integrated manner from both ends of the support base in its longitudinal direction. In this embodiment, the resonance frequency for driving can be adjusted by applying the trimming treatment (excising treatment) to the first projection, and the resonance frequency for detection can be adjusted by applying the trimming treatment (excising treatment) to the second projection. Namely, the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving.
- It is preferable that the adjustment for the resonance frequency for driving is performed by applying a trimming treatment to the third plate-shaped section in its widthwise direction, and the adjustment for the resonance frequency for detection is performed by applying a trimming treatment to the first plate-shaped section of the detecting section in its widthwise direction.
- This embodiment lies in the method in which the resonance frequencies for driving and detection are adjusted by changing spring constants of the first and third plate-shaped sections, rather than that the resonance frequencies for driving and detection are adjusted by changing masses of the vibrators and the support base. Therefore, it is unnecessary to form the first and second projections at the free ends of the vibrators and at the both ends of the support base in the longitudinal direction respectively. Accordingly, the production steps can be simplified. Further, since the regions to be subjected to the trimming treatment are thin-walled, the resonance frequency can be easily adjusted. Unlike the method in which the resonance frequency is adjusted by changing the mass, the resonance frequency for driving and the resonance frequency for detection can be adjusted completely independently.
- It is preferable that the resonance frequency for detection is adjusted after the resonance frequency for driving is adjusted.
- FIG. 1 schematically shows a perspective view illustrating a first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 2 schematically shows an exploded perspective view illustrating the vibration gyro sensor shown in FIG. 1.
- FIG. 3 schematically shows a partial perspective view illustrating, in a magnified manner, a portion of a first plate-shaped section of the vibration gyro sensor shown in FIG. 1.
- FIG. 4 schematically shows a perspective view illustrating a second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 5 schematically shows a perspective view illustrating a third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 6 schematically shows a perspective view illustrating a fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 7 schematically shows a perspective view illustrating a fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 8 schematically shows a perspective view illustrating a sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 9 schematically shows a perspective view illustrating a seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 10 schematically shows a perspective view illustrating an eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 11 schematically shows a perspective view illustrating a ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 12 schematically shows a perspective view illustrating a tenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 13 schematically shows a perspective view illustrating an eleventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 14 schematically shows a perspective view illustrating a twelfth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 15 schematically shows a perspective view illustrating a preferred embodiment of the combined sensor according to the present invention.
- FIG. 16 schematically shows a perspective view illustrating another preferred embodiment of the combined sensor according to the present invention.
- FIG. 17 schematically shows illustrative production steps for the vibration gyro sensor according to the first embodiment shown in FIG. 1.
- FIG. 18 schematically shows illustrative production steps for the vibration gyro sensor according to the fifth embodiment shown in FIG. 7.
- FIG. 19 shows a perspective view illustrating a magnified electrode structure of the type based on the use of the longitudinal effect of the electric field-induced strain.
- FIG. 20 schematically shows a perspective view illustrating a thirteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 21 schematically shows a perspective view illustrating a fourteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 22 schematically shows a perspective view illustrating a fifteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 23 schematically shows a perspective view illustrating a sixteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 24 schematically shows a perspective view illustrating an exemplary structure of projections used to adjust the resonance frequency in the vibration gyro sensor according to the fifteenth embodiment.
- FIG. 25 schematically shows a perspective view illustrating another exemplary structure of projections used to adjust the resonance frequency in the vibration gyro sensor according to the fifteenth embodiment.
- FIG. 26 schematically shows a perspective view illustrating a seventeenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 27 schematically shows a perspective view illustrating an exemplary structure used to adjust the resonance frequencies for driving and detection by changing spring constants of the driving and detecting sections in the vibration gyro sensor according to the seventeenth embodiment.
- FIG. 28 schematically shows a perspective view illustrating an eighteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 29 schematically shows a perspective view illustrating a nineteenth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 30 schematically shows a perspective view illustrating a twentieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 31 schematically shows a perspective view illustrating a twenty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 32 schematically shows a perspective view illustrating a twenty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 33 schematically shows a perspective view illustrating a twenty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 34 schematically shows a perspective view illustrating a twenty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 35 schematically shows a perspective view illustrating a twenty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 36 schematically shows a perspective view illustrating a twenty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 37 schematically shows a perspective view illustrating an exemplary wiring formation pattern led from pairs of electrodes of piezoelectric/electrostrictive elements in the vibration gyro sensor according to the seventeenth embodiment.
- FIG. 38 schematically shows a perspective view illustrating a twenty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 39 schematically shows a perspective view illustrating a twenty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 40 schematically shows a perspective view illustrating a twenty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 41 schematically shows a perspective view illustrating a thirtieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 42 schematically shows a perspective view illustrating a thirty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 43 shows a cross-sectional view taken along a line A-A shown in FIG. 42.
- FIG. 44 schematically shows a perspective view illustrating a thirty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 45 schematically shows a perspective view illustrating a thirty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 46 schematically shows a perspective view illustrating a thirty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 47 schematically shows a perspective view illustrating a thirty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 48 shows a cross-sectional view taken along a line B-B shown in FIG. 47.
- FIG. 49 schematically shows a perspective view illustrating a thirty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 50 schematically shows a perspective view illustrating a thirty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 51 schematically shows a perspective view illustrating a thirty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 52 schematically shows a perspective view illustrating a thirty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 53 shows characteristic curves illustrating the change in resonance angular frequency ratio depending on the length of the support rod for supporting the tuning fork.
- FIG. 54 schematically shows a perspective view illustrating a fortieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 55 schematically shows a perspective view illustrating a forty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 56 schematically shows a perspective view illustrating a forty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 57 schematically shows a perspective view illustrating a forty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 58 schematically shows a perspective view illustrating a forty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 59 schematically shows a perspective view illustrating a forty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 60 schematically shows a perspective view illustrating a forty-sixth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 61 schematically shows a perspective view illustrating a forty-seventh preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 62 shows a magnified structure of a portion at which lead wires are led in the vibration gyro sensor according to the forty-seventh embodiment.
- FIG. 63 schematically shows a perspective view illustrating a forty-eighth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 64 shows a magnified structure of a portion at which lead wires are led in the vibration gyro sensor according to the forty-eighth embodiment.
- FIG. 65 schematically shows a perspective view illustrating a forty-ninth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 66 schematically shows a perspective view illustrating a fiftieth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 67 schematically shows a perspective view illustrating a fifty-first preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 68 schematically shows a perspective view illustrating a fifty-second preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 69 schematically shows a perspective view illustrating a fifty-third preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 70A shows a cross-sectional view taken along a line C-C shown in FIG. 69.
- FIG. 70B shows a cross-sectional view taken along a line D-D shown in FIG. 69.
- FIG. 70C shows a cross-sectional view taken along a line E-E shown in FIG. 69.
- FIG. 71 schematically shows a perspective view illustrating a fifty-fourth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 72 schematically shows a perspective view illustrating a fifty-fifth preferred embodiment of the vibration gyro sensor according to the present invention.
- FIG. 73 schematically shows an exploded perspective view illustrating another structure of the vibration gyro sensor according to the first embodiment shown in FIG. 1.
- FIG. 74 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-third embodiment shown in FIG. 45.
- FIG. 75 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-fourth embodiment shown in FIG. 46.
- FIG. 76 schematically shows an exploded perspective view illustrating the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47.
- The feature of the present invention will be described in detail below with reference to various embodiments of the vibration gyro sensor illustrated in the drawings in order to more specifically and clearly describe the present invention.
- At first, an embodiment (first embodiment) of the vibration gyro sensor according to the present invention is shown in FIG. 1. In this embodiment, two angular rod-shaped
vibrators vibrators support base 4 composed of a fired product of ceramics respectively so that thevibrators support base 4. Each of thevibrators section 6 to serve as a detecting section which is formed in an integrated manner with its thin-walled region disposed fairly close to thesupport base 4 and with its principal surface extending in a direction of arrangement of thevibrators vibrators section 8 which has its width thinner than a width of thevibrator 2 and has its principal surfaces extending in a direction perpendicular to the first plate-shapedsection 6. Thevibrators support base 4 via the second plate-shapedsections vibrators sections sections section 10 which is more thin-walled than thevibrators sections vibrators support base 4, the first plate-shapedsections sections section 10 are constructed by an integrated fired product made of ceramics, thus giving an integrated structure. - Namely, as shown in FIG. 2, the vibration gyro sensor, which is constructed by the integrated fired product of ceramics as described above, can be grasped as an integrated stacked structure comprising a
thin plate layer 22, asubstrate layer 24, and aspacer layer 26. Accordingly, the first plate-shapedsections section 10 are given by thethin plate layer 22, while thevibrators sections thin plate layer 22 and thesubstrate layer 24. Further, thesupport base 4 is given by stacking and integrating thethin plate layer 22, thesubstrate layer 24, and thespacer layer 26. - Detecting piezoelectric/
electrostrictive elements sections respective vibrators electrostrictive element 12 is directly formed on the first plate-shapedsection 6 in a form in which a thin film-shapedlower electrode 12 a, a piezoelectric/electrostrictive layer 12 b, and anupper electrode 12 c are stacked and integrated with each other. The detecting piezoelectric/electrostrictive elements vibrators vibrators electrostrictive element 14 to serve as a driving means is formed in an integrated manner on the third plate-shapedsection 10, as constructed in the same manner as the detecting piezoelectric/electrostrictive elements electrostrictive element 14 is operated, the twovibrators - Thin-walled
excisable sections respective vibrators support base 4, and theexcisable sections excisable sections support base 4 is flush with the upper surfaces of thevibrators support base 4 has a shape with its thickness which is thicker than that of thevibrators support base 4 is located at a position lower than thevibrators support base 4 includes, in an integrated manner, aspacer section 18 corresponding to thespacer layer 26 shown in FIG. 2. Thesupport base 4 is thicker than thevibrators spacer section 18. When the vibration gyro sensor is attached at the portion of thesupport base 4 to a flat attachment plane in the vertical direction by the aid ofbolts 20, thevibrators spacer section 18 as described above. - Therefore, the vibration gyro sensor having the structure as described above is operated as follows. Namely, the third plate-shaped
section 10 undergoes deformation by operating the driving piezoelectric/electrostrictive element 14. Accordingly, the twovibrators vibrators vibrators vibrators vibrators electrostrictive elements - As described above, the vibration gyro sensor is constructed as a whole by the integrated fired product made of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. For this reason, no problem occurs, i.e., the characteristics of the sensor are not affected by any ambient magnetic field. The detecting piezoelectric/
electrostrictive elements electrostrictive element 14 are directly formed in the integrated manner on the first plate-shapedsections section 10 in accordance with the film formation method. No adhesive layer exists at all between the elements and the plate-shaped sections. Therefore, the problem of decrease in sensitivity, which would be otherwise caused by the absorption of stress brought about by such an adhesive layer, is effectively dissolved. - It is a matter of course that the deformation is advantageously caused by the operation of the driving piezoelectric/
electrostrictive element 14, owing to the fact that the driving piezoelectric/electrostrictive element 14 to serve as an actuator is formed in the integrated manner on the thin-walled third plate-shapedsection 10. Further, therespective vibrators support base 4 via the thin-walled second plate-shapedsections sections vibrators vibrators electrostrictive element 14. Especially, when the ratio of the width (thickness) to the height of the second plate-shapedsection 8 is made small, it is possible to suppress vibration in the vertical direction (y axis direction) which serves as a factor to decrease the sensitivity. Further, as for the region of arrangement of the detecting piezoelectric/electrostrictive element 12, the first plate-shapedsection 6, on which the detecting piezoelectric/electrostrictive element 12 is formed in the integrated manner, is formed to be more thin-walled than thevibrator 2 so that its principal surface extends in the direction of vibration (x axis direction) of thevibrator 2, in other words, the principal surface is located within the vibration plane of thevibrator 2. Accordingly, large displacement is obtained when bending vibration is generated in the y axis direction which is the direction perpendicular to the x axis direction. - As described above, the easily bendable regions exist in any of the direction of detecting vibration (direction of the y axis) and the direction of driving vibration (direction of the x axis), and hence large displacement is obtained in any of the driving and detecting operations. Accordingly, the sensitivity of the vibration gyro sensor is extremely enhanced. Especially, the first plate-shaped
section 6, on which the detecting piezoelectric/electrostrictive element 12 is formed for giving the detecting section, is thin-walled to provide the structure so that the stress is concentrated. Thus a large output is obtained. - In the embodiment described above, there is provided the thin-walled
excisable section 16 which extends in the integrated manner from the forward end of thevibrator 2. Therefore, theexcisable section 16 is easily subjected to the trimming processing or machining such as the laser machining and the ultrasonic machining, making it easy to adjust the resonance frequency of thevibrator 2. The electrode area of the detecting piezoelectric/electrostrictive element 12 and the driving piezoelectric/electrostrictive element 14 can be easily changed by using a laser or the like, making it possible to easily adjust the electric characteristics thereof. - Further, the vibration gyro sensor according to this embodiment has the structure in which the third plate-shaped
section 10, on which the driving piezoelectric/electrostrictive element 14 is provided, is formed in the integrated manner so that the twovibrators vibrators section 10. - The vibration gyro sensor according to the present invention may be embodied by various structures other than the structure described above, within a range without deviating from the gist or essential characteristics of the present invention. Representative embodiments are shown in FIG. 4 and followings. The following embodiments will be explained only for their characteristic portions. The same or equivalent components or parts as those described in the first embodiment are designated by the same reference numerals, detailed explanation of which will be omitted.
- At first, a second embodiment shown in FIG. 4 has the following feature. Namely,
vibrators U-shaped support base 4 via thin-walled first plate-shapedsections sections vibrators section 10 for connecting the twovibrators sections - In the second embodiment, the third plate-shaped
section 10 is provided at the position nearer to the forward ends of thevibrators vibrators section 10, it is still possible to obtain displacement which is larger than that obtained by the conventional vibration gyro sensor. - Third and fourth embodiments shown in FIGS. 5 and 6 respectively have the following feature as compared with the first and second embodiments described above. Namely, the vibration gyro sensor is constructed by an integrated fired product made of ceramics having a structure in which an angular bar-shaped
support bar 28 having a rectangular cross section is arranged between twovibrators vibrators - Namely, the
support bar 28 is disposed between the twovibrators vibrators support base 4. Thin-walled third plate-shapedsections support bar 28 and thevibrators electrostrictive elements sections electrostrictive elements vibrators - FIGS. 7 and 8 show fifth and sixth embodiments having the following structure respectively. Namely, an integrated fired structure of ceramics is used in a state in which the
support base 4 for supporting twovibrators attachment frame 30 having a rectangular configuration. The twovibrators attachment frame 30, and predetermined gaps are formed between thevibrators attachment frame 30. - Independent driving means (actuators) are provided in an integrated manner between the two
vibrators attachment frame 30 which surrounds the twovibrators sections vibrators attachment frame 30 opposing thereto. Driving piezoelectric/electrostrictive elements sections - In the vibration gyro sensor having the structure as described above, the
attachment frame 30 can be tightly fixed to a flat attachment plane via thespacer section 18 by the aid ofbolts 20 or the like. Accordingly, the vibration gyro sensor is advantageous in that the degree of freedom is large concerning the place for installation. - Seventh and eighth embodiments shown in FIGS. 9 and 10 have similar structures as those described in the first and second embodiments concerning the
support base 4. However, thesupport base 4 is provided as an integrated fired structure made of ceramics in a form of anattachment frame 30 having a rectangular configuration so that the twovibrators - Namely, each of the vibration gyro sensors according to the seventh and eighth embodiments includes a driving means10, 14 formed in an integrated manner between the two
vibrators attachment frame 30 having the rectangular frame structure. In these embodiments, theattachment frame 30 can be tightly fixed via thespacer section 18 in the same manner as described in the fifth and sixth embodiments. These embodiments are also advantageous in that the degree of freedom is large concerning the place for installation. - FIG. 11 shows a ninth embodiment of the vibration gyro sensor according to the present invention. The vibration gyro sensor is constructed by an integrated fired product structure made of ceramics wherein a
frame 32 having a rectangular configuration, which serves as a support base for supporting twovibrators vibrators section 8, which is provided to lower the rigidity of thevibrators frame 32 located between support regions for the twovibrators section 8 gives its principal surface extending in a direction perpendicular to the direction of vibration (arrangement plane for thevibrators 2, 2). A third plate-shapedsection 10, which is more thin-walled than theframe 32, is formed at a portion of theframe 32 opposing to the region for forming the second plate-shapedsection 8 so that the third plate-shapedsection 10 has its principal surface parallel to the principal surfaces of the first plate-shapedsections electrostrictive element 14 is formed in an integrated manner on the third plate-shapedsection 10 in accordance with the film formation method. - Therefore, in the vibration gyro sensor having the structure as described above, the operation of the driving piezoelectric/
electrostrictive element 14 causes deformation of the third plate-shapedsection 10 which induces bending vibration in theframe 32 by using the region of the second plate-shapedsection 8 as a center. On the basis of the bending vibration, the twovibrators - FIGS. 12 and 13 show tenth and eleventh embodiments respectively, each based on the use of an integrated fired product structure made of ceramics, as illustrative structures for facilitating fixation of the vibration gyro sensor shown in FIG. 11.
- Of the tenth and eleventh embodiments, the embodiment shown in FIG. 12 includes an
attachment section 34 for fixing aframe 32, which is provided in an integrated manner at an outer surface corresponding to a region for forming the second plate-shapedsection 8 formed in therectangular frame 32. Specifically, theattachment section 34 has a triangular configuration, and it is connected in an integrated manner to the outer surface of the second plate-shapedsection 8 at an apex of the triangle. The connecting section, at which theattachment section 34 is connected to the second plate-shapedsection 8, has a width (length in the lateral direction in FIG. 12) which is smaller than a width of the second plate-shaped section 8 (length in the lateral direction in FIG. 12) because of the following reason. Namely, it is desirable to suppress, as small as possible, the restriction on the deformation of the second plate-shapedsection 8, which would be caused by the connection of theattachment section 34. The vibration gyro sensor is fixed such that theattachment section 34 is fixed via thespacer section 18 by the aid ofbolts 20 or the like. - The embodiment shown in FIG. 13 illustrates a modified embodiment of the
attachment section 34 as described in the embodiment shown in FIG. 12. Namely, this embodiment has a structure including, in an integrated manner, anattachment frame 36 which is disposed outside theframe 32 and separated therefrom by predetermined distances so that theframe 32 for giving the vibration gyro sensor is surrounded. A tight fixing structure can be realized by fixing theattachment frame 36 having a rectangular frame configuration by usingbolts 20. - A twelfth embodiment of the vibration gyro sensor according to the present invention is shown in FIG. 14, based on the use of an integrated fired product structure made of ceramics. In this embodiment, a
support base 4, which is provided for supporting twovibrators section 8 is formed at a portion located between support regions of thesupport base 4 for the twovibrators attachment section 34 for fixing thesupport base 4 is connected in an integrated manner to the outer surface of the second plate-shapedsection 8, in the same manner as the embodiment shown in FIG. 13. Anattachment frame 36 having a rectangular frame configuration, which is formed in an integrated manner together with theattachment section 34, is disposed outside the twovibrators support base 4 and separated by predetermined distances therefrom so that the twovibrators support base 4 are surrounded thereby. - Third plate-shaped
sections attachment frame 36 and thesupport base 4, are formed in an integrated manner with their principal surfaces parallel to principal surfaces of first plate-shapedsections sections attachment frame 36 and portions of thesupport base 4 located on both sides of the second plate-shapedsection 8 respectively. Driving piezoelectric/electrostrictive elements sections - In the vibration gyro sensor having the structure as described above, the portions of the
support base 4 located on the both sides of the second plate-shapedsection 8 are vibrated by the operation of the driving piezoelectric/electrostrictive elements attachment section 36 and the portions of thesupport base 4. On the basis of the vibration, thevibrators - The use of the structure of the vibration gyro sensor according to the present invention as described above makes it possible to easily realize combination with other sensors. Specifically, the attachment frames30, 36 shown in FIGS. 7 to 10 and FIGS. 13 and 14 may be utilized to provide a second attachment frame which is adjacent to the attachment frame and integrated with the attachment frame, as an integrated fired product structure made of ceramics. Another sensor, which has a function different from that of the vibration gyro sensor, is supported in an integrated manner in the second attachment frame. Thus it is possible to provide a combined sensor. An illustrative embodiment of such a combined sensor is shown in FIG. 15.
- In a combined sensor illustrated in FIG. 15, a
second attachment frame 38 integrated with anattachment frame 36 is provided as an integrated fired product structure made of ceramics, thesecond attachment frame 38 being adjacent to theattachment frame 36 of the vibration gyro sensor as shown in FIG. 13. An acceleration sensor, which has a function distinct from the vibration gyro sensor, is provided in an integrated manner in thesecond attachment frame 38. In FIG. 15, anacceleration sensor section 40 for detecting the angular velocity around the z axis, which constructs the vibration gyro sensor, is provided on the left side of the system. Anacceleration sensor section 42 is formed in thesecond attachment frame 38 on the right side of the system. Namely, theacceleration sensor section 42 comprises afirst sensor 44A and asecond sensor 44B for detecting the acceleration in the y axis direction, and athird sensor 44C and afourth sensor 44D for detecting the acceleration in the x axis direction. - Each of the first and
second sensors vibrator section vibrator attachment frame 38 in an integrated manner, and a detecting piezoelectric/electrostrictive element section electrostrictive element 14 described above. Therefore, when an acceleration in the y axis direction is inputted, the detectingsections electrostrictive elements second sensors - Each of the third and
fourth sensors vibrator section vibrator attachment frame 38 in an integrated manner, a detecting piezoelectric/electrostrictive element section electrostrictive element 12 described above, and a thin plate-shaped connectingsection 46 c′, 46 d′ for connecting thevibrator attachment frame 38 to support thevibrator vibrator electrostrictive elements sections - FIG. 16 shows another embodiment of the combined sensor having a different structure. A combined sensor disclosed in FIG. 16 has an integrated fired product structure made of ceramics in which an angular
velocity sensor section 40 and anacceleration sensor section 42 are provided in an integrated manner, in the same manner as the combined sensor illustrated in FIG. 15. However, this embodiment is different from the foregoing embodiment in the structures of the first andsecond sensors - Namely, a connecting
section 46 a′, 46 b′, which is provided for connecting, in an integrated manner, avibrator second sensors attachment frame 38 respectively, is formed to have a thin plate configuration which is easily deformed in the z axis direction. Therefore, when an acceleration in the z axis direction is inputted, thevibrators sections 46 a′, 46 b′ to be easily deformed, on the basis of which a predetermined electromotive force (voltage) is outputted by the detecting piezoelectric/electrostrictive elements - Any of the vibration gyro sensors and the combined sensors according to the present invention is composed of the integrated fired product made of ceramics except for the piezoelectric/
electrostrictive elements - At first, in the present invention, the main sensor body, which comprises, for example, the
vibrators 2, thesupport base 4, the first to third plate-shapedsections spacer section 18, is given by the integrated fired product made of ceramics. Those usable, without any problem, as materials for forming the integrated fired product of ceramics for providing the main sensor body include any of ceramic materials composed of oxide and any of ceramic materials composed of those other than oxide, provided that the material is an insulative material or a dielectric material having large mechanical strength, which can be subjected to a heat treatment at about 1400° C. as described later on, and which can be stacked and integrated with the piezoelectric/electrostrictive elements - In order to stabilize zirconium oxide, the foregoing compound is preferably added in an amount of 1 mole % to 30 mole % in the case of yttrium oxide and ytterbium oxide, 6 mole % to 50 mole % in the case of cerium oxide, or 5 mole % to 40 mole % in the case of calcium oxide and magnesium oxide. Especially, it is desirable to use yttrium oxide as a stabilizer. In this case, yttrium oxide is desirably added in an amount of 1.5 mole % to 6 mole %, more preferably 2 mole % to 4 mole %. When yttrium oxide is added to zirconium oxide in the foregoing range of addition, the crystal phase is partially stabilized, thus giving excellent characteristics for the main sensor body.
- When stabilized or partially stabilized zirconia is used for the thin plate layer, it is preferable to contain an auxiliary shown in the following table. An equivalent effect can be obtained even when the piezoelectric/electrostrictive element contains the following auxiliary.
TABLE Type of Preferable More applicable content preferable electric range range field-induced Auxiliary (% by weight) (% by weight) Effect strain alumina 0.1˜5.0 0.2˜2.0 *1 lateral effect titania 0.1˜5.0 0.2˜2.0 *2 longitudinal effect - As shown in FIG. 2, the integrated fired product of ceramics, which constructs the main sensor body as described above, advantageously comprises the
thin plate layer 22, thesubstrate layer 24, and thespacer layer 26, if necessary. It is advantageous to contain silicon oxide (SiO, SiO2) at least in the material to give thethin plate layer 22. The content of silicon oxide is preferably not less than 0.5% by weight and not more than 5% by weight, and especially desirably not less than 1% by weight and not more than 3% by weight. The content of silicon oxide in the ratio as described above is effective to avoid any excessive reaction with the piezoelectric/electrostrictive material during the heat treatment for the piezoelectric/electrostrictive element thin plate layer 22 so that good actuator characteristics or detection characteristics may be obtained. - Further, in order to obtain quick response and large displacement in the vibration gyro sensor and the combined sensor including the same according to the present invention, the thickness of the
thin plate layer 22 on which the piezoelectric/electrostrictive elements are formed in the integrated manner, i.e., the thickness of the first plate-shapedsection 6 and the third plate-shapedsection 10 is generally not more than 50 μm, preferably not more than 30 μm, and more preferably not more than 15 μm. On the other hand, the thickness of thesubstrate layer 24 is appropriately determined. However, the thickness of thesubstrate layer 24 is generally not less than 30 μm, preferably not less than 50 μm, and more preferably not less than 100 μm. In order to obtain large displacement and large generated force in the actuator or the detecting section, at least thethin plate layer 22 preferably has an average particle diameter of crystals of 0.1 to 2 μm. More preferably, thethin plate layer 22 is desirably composed of a ceramic material having an average particle diameter of not more than 1 μm. - Those usable to obtain the integrated fired product of ceramics to give the main sensor body comprising the
thin plate layer 22 and the substrate layer 24 (and the spacer layer 26) as described above include, for example, a green sheet stacking method for stacking, in a state of green sheets, thethin plate layer 22, thesubstrate layer 24, and thespacer layer 26, as well as various molding methods based on the use of a mold, such as pressure molding, casting molding, and injection molding, and processing or machining methods for forming, for example, thevibrator 2, thesupport base 4, and the first to third plate-shapedsections thin plate layer 22 is high. The green sheet stacking method is preferably based on the use of first, second, and third green sheets for providing thethin plate layer 22, thesubstrate layer 24, and thespacer layer 26 respectively. A method is adopted, in which the first, second, and third green sheets are stacked by means of thermal adhesion under a pressure, and then they are integrated with each other by firing. It is preferable to use, as the first to third green sheets, green sheets which at least have the same degree of percentage of contraction by firing, upon the firing and integration. - The green sheet stacking method as described above specifically includes the following three methods. In the first method, the first to third green sheets are formed to have shapes corresponding to the
thin plate layer 22, thesubstrate layer 24, and thespacer layer 26 shown in FIG. 2 respectively. They are stacked and integrated with each other, followed by firing to produce an integrated fired product. After that, the piezoelectric/electrostrictive elements thin plate layer 22 in accordance with the film formation method. In the second method, the first green sheet, to which the shape of thethin plate layer 22 is not given, is stacked and integrated with the second and third green sheets having shapes corresponding to thesubstrate layer 24 and thespacer layer 26, and they are fired to obtain an integrated fired product. After that, the shape of thethin plate layer 22 is realized by means of, for example, laser machining and ultrasonic machining, and then the piezoelectric/electrostrictive elements are formed in an integrated manner at predetermined regions on thethin plate layer 22. In the third method, the first green sheet, to which the shape of thethin plate layer 22 is not given, is used. The first green sheet is stacked and integrated with the second and third green sheets having shapes corresponding to thesubstrate layer 24 and thespacer layer 26, followed by firing to produce an integrated fired product. Piezoelectric/electrostrictive elements are formed in an integrated manner at predetermined regions of fired product portions of the first green sheet. After that, the shape of thethin plate layer 22 is realized by means of, for example, laser machining and ultrasonic machining. Thus the objective vibration gyro sensor is obtained. Especially, the present invention advantageously adopts the last-mentioned third method in order to avoid deformation which would be caused by the heat treatment during formation of the piezoelectric/electrostrictive elements. The shapes of thethin plate layer 22, thesubstrate layer 24, and thespacer layer 26 are preferably realized by using the method in which the green sheets are shaped to give such shapes, or by adopting, for example, laser machining, press working with a mold, and ultrasonic machining. Especially, the press working with a mold is advantageously used, because this method is excellent in mass production performance and integration performance. - FIG. 17 shows an example of the desirable production technique (third method) for the vibration gyro sensor in accordance with the green sheet stacking method as described above. In this procedure, a first
green sheet 52 for giving thethin plate layer 22 is not processed into the shape of thethin plate layer 22 at all. The firstgreen sheet 52 is merely used as one thin plate having a rectangular configuration. A secondgreen sheet 54 for giving thesubstrate layer 24 is processed into the shape corresponding to the shape of thesubstrate layer 24. A thirdgreen sheet 56 for giving thespacer layer 26 is also processed into the shape corresponding to the shape of thespacer layer 26. The first, second, and thirdgreen sheets electrostrictive elements thin plate layer 22 of the obtained firedproduct 58 in accordance with the film formation method as described later on. Subsequently, cutting processing is applied to portions of thethin plate layer 22 of the integrated firedproduct 58 by means of, for example, laser machining or ultrasonic machining. Thus the vibration gyro sensor as shown in FIG. 1 is completed. - In the case of the second method based on the green sheet stacking method described above, the order of the step of forming the piezoelectric/
electrostrictive elements thin plate layer 22 is inverted, and the piezoelectric/electrostrictive elements - In the green sheet stacking method in which the vibration gyro sensor is obtained by stacking the first, second, and third
green sheets excisable section 16 extending from the forward end of thevibrator 2 by considering the shape of thethin plate layer 22. After the vibration gyro sensor is produced, the resonance frequency is measured, and theexcisable section 16 formed at the forward end of thevibrator 2 is cut (excised) by means of, for example, laser machining and ultrasonic machining, if necessary. Thus the resonance frequency can be finely adjusted with ease. - As clarified from FIGS. 2 and 17, the vibration gyro sensor shown in FIG. 1 is constructed such that the second
green sheet 54 for giving thesubstrate layer 24 has a discontinuous structure of a form in which the portions for giving thevibrators sections thin plate layer 22 which is given by the firstgreen sheet 52. For this reason, it is difficult to position such discontinuous sections. Further, there is an implicit problem that deformation tends to occur during the firing and the heat treatment performed when the piezoelectric/electrostrictive elements are formed. Therefore, a technique is preferably adopted, in which a continuous green sheet is prepared and used during stacking, and discontinuous sections as described above are formed after completion of the stacking and integration or the firing and integration. An example of such a technique is shown in FIG. 18. - Namely, FIG. 18 shows one of effective techniques to produce the vibration gyro sensor shown in FIG. 7. In this procedure, a second
green sheet 54 for giving thesubstrate layer 24 is provided as a continuous sheet as shown in FIG. 18. Namely,sections vibrators sections section 60 for forming theattachment frame 30, and thus the secondgreen sheet 54 is used in a state including no discontinuous portion. The secondgreen sheet 54 is stacked together with a firstgreen sheet 52 and a thirdgreen sheet 56, and they are fired and integrated with each other. After that, the piezoelectric/electrostrictive elements thin plate layer 22 given by the firstgreen sheet 52. Simultaneously with the machining, or before or after the machining, the connectingsections vibrators attachment frame 30, are cut by means of, for example, laser machining or ultrasonic machining to make separation from theattachment frame 30. When cutsections sections vibrators attachment frame 30. Thus the vibration gyro sensor shown in FIG. 7 is completed. - The structure, in which any discontinuous section is not exist in the second
green sheet 54 as described above, may be realized not only for the sensors having the structure which includes theattachment frame frame 32 so that thevibrators support bar 28 provided between the twovibrators sections vibrators support bar 28, and they are finally cut at thecut sections - In the production steps for the vibration gyro sensors and the combined sensors described above, the piezoelectric/
electrostrictive elements thin plate layer 22 as follows. - At first, in order to form the
electrode films electrostrictive film 12 b composed of respective materials on the predetermined regions on thethin plate layer 22, it is possible to appropriately adopt various known film formation methods including, for example, thick film methods such as screen printing, application methods such as dipping, and thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating. However, there is no limitation thereto at all. In order to form the piezoelectric/electrostrictive film 12 b, it is preferable to adopt techniques based on, for example, screen printing, dipping, and application. In these techniques, the film can be formed on thethin plate layer 22 by using a paste or a slurry comprising, as a major component, piezoelectric/electrostrictive ceramic particles, in which good operation characteristics can be obtained. When the piezoelectric/electrostrictive element thin plate layer 22 without using any adhesive. Accordingly, the use of the film formation method is especially preferred because the reliability and the reproducibility are excellent, and it is easy to achieve integration. The shape of such a film is formed by means of pattern formation by using, for example, the screen printing method and the photolithography method. Alternatively, the pattern may be formed by removing unnecessary portions by using mechanical processing methods such as laser processing, slicing, and ultrasonic processing. - The shape of the film and the structure of the piezoelectric/
electrostrictive element thin plate layer 22 in accordance with the film formation method are not limited at all, to which those hitherto known may be appropriately adopted. For example, other than the structure based on the use of the lateral effect of the electric field-induced strain as shown in FIG. 3, it is possible to appropriately adopt those having a structure based on the use of the longitudinal effect of the electric field-induced strain. No problem occurs concerning the shape of the film. The shape of the film may be any of polygonal configurations such as triangles and rectangles, circular configurations such as circles, ellipses, and rings, comb-shaped configurations, lattice-shaped configurations, and special configurations obtained by combining the foregoing configurations. - The
respective films sections thin plate layer 22, may be heat-treated every time when each film is formed so that the integrated structure is established together with the respective plate-shaped sections. Alternatively, all of the films may be formed, and then they may be simultaneously heat-treated so that the respective films may be simultaneously joined with the plate-shaped section in an integrated manner. Incidentally, when the electrode film is formed by means of the thin film formation technique, the heat treatment is not necessarily indispensable to achieve integration in some cases. - As for the heat treatment temperature to integrate the films formed as described above and the plate-shaped section, a temperature of about 800° C. to 1400° C. is generally adopted, and preferably, a temperature within a range of 1000° C. to 1400° C. is advantageously selected. When the piezoelectric/
electrostrictive film 12 b is heat-treated, it is preferable to perform the heat treatment while controlling the atmosphere by using an evaporation source composed of a piezoelectric/electrostrictive material together so that the composition of the piezoelectric/electrostrictive film is not unstable at a high temperature. - The material for the
electrode films - As for the mixture described above, it is desirable to use, as the ceramic to be added to the metal and the alloy, the same material as the material for constructing the first plate-shaped section and the third plate-shaped section or the piezoelectric/electrostrictive material described later on. The same material as the material for the plate-shaped section is preferably added in an amount of 5 to 30% by volume. The same material as the piezoelectric/electrostrictive material is preferably added in an amount of about 5 to 20% by volume. Especially, the mixture, which is obtained by mixing the metal or the alloy described above with the material for constructing the plate-shaped section and the piezoelectric/electrostrictive material, is advantageously used to form the objective electrode.
- The
electrodes - Any material may be used as the piezoelectric/electrostrictive material to give the film-shaped piezoelectric/
electrostrictive layer 12 b for constructing the piezoelectric/electrostrictive elements - Specifically, those preferably used as the piezoelectric/electrostrictive material employed in the present invention include, for example, materials comprising a major component of lead zirconate titanate (PZT system), materials comprising a major component of lead magnesium niobate (PMN system), materials comprising a major component of lead nickel niobate (PNN system), materials comprising a major component of lead zinc niobate, materials comprising a major component of lead manganese niobate, materials comprising a major component of lead antimony stannate, materials comprising a major component of lead titanate, materials comprising a major component of barium titanate, and composite materials thereof. No problem occurs when the material comprising the major component of the PZT system is appropriately added with predetermined additives to give materials, for example, those of the PLZT system containing, as additives, oxides of lanthanum, barium, niobium, zinc, nickel, and manganese, or other types of compounds thereof.
- It is desirable that the thickness of the piezoelectric/
electrostrictive element - The present invention has been specifically described above on the basis of the several embodiments. However, the present invention should not be interpreted at all as one which is limited by the foregoing embodiments. It should be understood that various changes, modifications, and improvements may be added to the present invention on the basis of the knowledge of those skilled in the art without deviating from the scope of the present invention.
- For example, in the illustrative respective embodiments, the
spacer section 18 is provided, for example, for thesupport base 4, theattachment frame attachment section 34 so that therespective vibrators vibrators spacer section 18 depending on the shape or the structure of the attachment plane. - In the illustrative embodiments, for example, the
support base 4, theattachment frame attachment section 34 is fixed by using the bolts. However, it is also effective to glue and fix such components by using an adhesive. In this case, it is preferable to fix the entire lower surface of thespacer section 18 by using an adhesive. Those usable as the adhesive include, for example, those of the epoxy resin type, the acrylic resin type, the synthetic rubber type, the hot melt type, the cyanoacrylate type, and the polyurethane resin type. - In the illustrative vibration gyro sensor according to the present invention, the first plate-shaped
section 6, on which the detecting piezoelectric/electrostrictive element 12 is formed in the integrated manner, is provided at the intermediate portion or the proximal end of thevibrator 2. However, as shown in FIGS. 20 and 21, it is possible to provide the first plate-shapedsection 6 at the forward end of thevibrator 2 to give an integrated structure continued to theexcisable section 16. In this case, the Coriolis force applied to the detecting piezoelectric/electrostrictive element 12 is lowered, and the sensitivity is decreased. However, this structure has a feature that it is advantageous concerning achievement of a compact size and concerning breakage. - Next, a fifteenth embodiment of the vibration gyro sensor according to the present invention will be described with reference to FIG. 22.
- The vibration gyro sensor according to the fifteenth embodiment comprises a rectangular parallelepiped-shaped
support base 100 with its longitudinal direction extending in a certain direction (X direction in FIG. 22), twovibrators support base 100 and having their direction of major axes extending in a direction (Y direction in FIG. 22) perpendicular to the certain direction, twovibrators support base 100 and having their direction of major axes extending in the Y direction, and aframe 104 having its frame surface parallel to a plane including the X and Y directions, for surrounding thesupport base 100 and the fourvibrators 102A to 102D. - The respective two
vibrators support base 100 at the respective side surfaces so that they extend in parallel to one another while giving a predetermined spacing width “d”. - Each of the
vibrators 102A to 102D has a rectangular parallelepiped-shapedmain vibrator body 106, and a thin-walled plate-shaped connecting section (second plate-shaped section) 108 for connecting themain vibrator body 106 to thesupport base 100. The connectingsection 108 extends from a central portion in the widthwise direction of an end surface of themain vibrator body 106 on the side of thesupport base 100 to thesupport base 100. The height of the connectingsection 108 is approximately the same as that of themain vibrator body 106, and the width thereof is designed to be smaller than the width of themain vibrator body 106, in the same manner as described in the first embodiment (see FIG. 1). - An
opening 110, which has an approximately rectangular planar configuration, is formed through theframe 104 at its central portion. Theopening 110 penetrates through theframe 104 in its direction of height, and it has an opening area of a degree to make it possible to surround thesupport base 100 and the fourvibrators 102A to 102D. Theopening 110 hasrectangular cutouts 112 at portions corresponding to both longitudinal ends of thesupport base 100. The distance between bottoms of therespective cutouts 112 is designed to be longer than the length of thesupport base 100 in the longitudinal direction. Side surfaces of therespective cutouts 112 are opposed, at portions near to theopening 110, to the side surfaces of thesupport base 100. Namely, thesupport base 100 is formed such that its both ends in the longitudinal direction are inserted into the correspondingcutouts 112 respectively. - The respective two
vibrators support base 100, are provided with plate-shaped driving sections (third plate-shaped sections) 114 which are thin-walled in the direction of height and formed between themain vibrator bodies 106 respectively. In the illustrative embodiment shown in FIG. 22, each of the drivingsections 114 has its upper surface which is disposed on a side of the upper surface of themain vibrator body 106, and which is disposed at a position nearest to the connectingsections 108. Therespective driving sections 114 are actually disposed on the side of the upper surface of themain vibrator body 106. However, strictly speaking, they are convex upward or convex downward, giving a structure in which they are not in an identical plane (plate spring structure). - Plate-shaped
sections 116, which are thin-walled in their direction of height, are provided between portions of the both side surfaces of thesupport base 100 in the vicinity of the both ends in the longitudinal direction and side surfaces of thecutouts 112 opposing to the portions. In the illustrative embodiment shown in FIG. 22, the upper surfaces of the respective plate-shapedsections 116 are depicted in a state in which they are flush with the upper surface of thesupport base 100 and the upper surface of theframe 104. However, in fact, although the respective plate-shapedsections 116 are disposed on the side of the upper surface of thesupport base 100 and on the side of the upper surface of theframe 104, they are convex upward or convex downward. Strictly speaking, the respective plate-shapedsections 116 have a structure in which they are not disposed in an identical plane (plate spring structure). - In the vibration gyro sensor according to the fifteenth embodiment, the
support base 100, the fourvibrators 102A to 102D, theframe 104, the four connectingsections 108, the two drivingsections 114, and the four plate-shapedsections 116 are constructed by an integrated fired product made of ceramics. The vibration gyro sensor further comprises driving piezoelectric/electrostrictive elements 118 formed on the drivingsections 114, and detecting piezoelectric/electrostrictive elements 120 formed on the plate-shapedsections 116. Accordingly, driving means 122 for vibrating thevibrators 102 in an excited manner are constructed by the drivingsections 114 and the driving piezoelectric/electrostrictive elements 118, and detectingsections 124 are constructed by the plate-shapedsections 116 and the detecting piezoelectric/electrostrictive elements 120. When the driving piezoelectric/electrostrictive elements 118 are operated by applying an electric power thereto, the respective twovibrators - The connecting
sections 108 provided between themain vibrator bodies 106 and thesupport base 100 will now be described. The aspect ratio (width: height) of the connectingsection 108 is preferably within a range of 1:1.2 to 1:1000, and more preferably within a range of 1:1.8 to 1:50. The aspect ratio should be designed within the foregoing range because of the following reason. Namely, if the aspect ratio of the connectingsection 108 is larger than 1:1.2, unnecessary vibration in the Z axis direction tends to occur in thevibrators 102A to 102D. As a result, unnecessary vibration tends to occur in the detectingsections 124. On the other hand, if the aspect ratio is smaller than 1:1000, it is difficult to process and machine the connectingsections 108. As a result, the processing accuracy is deteriorated. - Integrated firing of the ceramics and formation of the piezoelectric/electrostrictive elements have been described in detail above, explanation of which will be omitted in this section.
- In the vibration gyro sensor according to the fifteenth embodiment, when the driving piezoelectric/
electrostrictive elements 118 are operated, the drivingsections 114 undergo deformation. Thus the respective twovibrators - When an angular velocity is applied around the axis (around the Z axis in FIG. 22) perpendicular to the plane including the certain direction and the extending direction of the
support base 100 in a state in which the respective-twovibrators sections 116 of the detectingsections 124. The force causes the detectingsections 124 to make lateral vibration. Namely, rotational vibration occurs around the Z axis, and the vibration is detected as an electromotive force (voltage) by the piezoelectric/electrostrictive elements 120 of the detectingsections 124. - In the present invention, all of the
vibrators 102, thesupport base 100, and the detectingsections 124 are constructed by the integrated fired product of ceramics. Therefore, there is no magnetic material such as the conventional elinvar alloy in the materials for constructing the vibration gyro sensor. Accordingly, the characteristics of the sensor are not affected by any ambient magnetic field. - The detecting
section 124 is constructed as having the plate-shapedsection 116 which is more thin-walled than themain vibrator body 106 in its direction of height so that it has a structure having low rigidity. Therefore, when the vibration is caused around the Z axis by the angular velocity as described above, a large strain or distortion is obtained in the plate-shapedsection 116. Thus it is possible to greatly improve the detection sensitivity of the detecting piezoelectric/electrostrictive element 120 formed on the plate-shapedsection 116. - Especially, in the vibration gyro sensor according to the fifteenth embodiment, the vibration is generated in the detecting
section 124 only when the angular velocity is applied. Therefore, the output (null voltage), which is obtained from the detecting piezoelectric/electrostrictive element 120 in a state in which no angular velocity is applied, is extremely small. Thus the detection sensitivity is greatly improved. Moreover, the probability of occurrence of fatigue fracture at the detectingsection 124 due to vibration is lowered, and it is possible to contemplate a long service life of the vibration gyro sensor. - The vibration gyro sensor has the structure not for measuring the angular velocity around the major axis of the vibrator106 (around the Y axis), but for measuring the angular velocity around the axis perpendicular to the plane which includes the certain direction and the extending direction of the support base 100 (around the Z axis). Therefore, the
vibrators 102, thesupport base 100, and theframe 104 can be made thin in their direction of height. Thus it is possible to facilitate realization of a compact size and a light weight of the vibration gyro sensor. - The four
vibrators 102A to 102D have the structure in which each of themain vibrator bodies 106 includes no thin-walled plate member and each of them is supported singly by thesupport base 100 having the high strength. Therefore, each of themain vibrator bodies 106 itself is allowed to have a large mass. Accordingly, the Coriolis force (Fc= 2 mv Ω) generated in thevibrators 102A to 102D is increased, and hence it is possible to realize a high sensitivity in relation to the detection of strain effected by the detectingsections 124. - Next, a vibration gyro sensor according to a sixteenth embodiment will be explained with reference to FIG. 23. Components or parts corresponding to those shown in FIG. 22 are designated by the same reference numerals, duplicate explanation of which will be omitted.
- As shown in FIG. 23, the vibration gyro sensor according to the sixteenth embodiment has approximately the same structure as that of the vibration gyro sensor according to the fifteenth embodiment (see FIG. 22). However, the detecting
sections 124 are different in the following points. - Namely, the detecting
section 124 comprises aring member 130 formed of ceramics in an integrated manner between a side surface of thecutout 112 and a portion of both side surfaces of thesupport base 100 in the vicinity of the both ends in the longitudinal direction, a plate-shapedsection 116 provided in an integrated and bridged manner in parallel to the extending direction of the support base 100 (X axis direction) in thering member 130, and a detecting piezoelectric/electrostrictive element 120 formed on the plate-shapedsection 116. - The vibration gyro sensor according to the sixteenth embodiment is operated as follows. Namely when an angular velocity is applied around the axis perpendicular to the plane including the certain direction and the extending direction of the support base100 (around the Z axis) in a state in which the respective two
vibrators electrostrictive elements 118, a force acts in the Y axis direction on the detectingsections 124. The action of the force causes thering members 130 to make vibration while forming elliptic configurations with their major or minor axis directed in the Y axis direction. The vibration of thering members 130 in the Y axis direction is detected as an electromotive force (voltage) by the detecting piezoelectric/electrostrictive elements 120. In the sixteenth embodiment, the strain in the detectingsections 124 in the Y axis direction is indirectly measured via the deformation of thering members 130 by using the detecting piezoelectric/electrostrictive elements 120. This embodiment provides an effect that the vibration gyro sensor is excellent in durability. - In the vibration gyro sensors according to the fifteenth and sixteenth embodiments, the resonance frequency is adjusted in the same manner as, for example, the vibration gyro sensor according to the first embodiment described above (see FIG. 1). The adjustment for the resonance frequency will be specifically explained with reference to FIGS. 24 and 25, as represented by the vibration gyro sensor according to the fifteenth embodiment.
- The gyro sensor according to the fifteenth embodiment is actually constructed as follows in order to adjust the resonance frequency. Namely, as shown in FIG. 24, thin-walled
first projections 132, which protrude outwardly from respective free ends of the respective twovibrators second projections 134, which protrude outwardly from both ends of thesupport base 100 in the longitudinal direction, are formed of ceramics in an integrated manner. - The resonance frequency for driving is adjusted by trimming-treating the
first projections 132, and the resonance frequency for detection is adjusted by trimming-treating thesecond projections 134. - In this embodiment, the resonance frequency for driving can be adjusted by applying a trimming treatment (excising treatment) to the
first projections 132, and the resonance frequency for detection can be adjusted by applying a trimming treatment (excising treatment) to thesecond projections 134. Namely, the resonance frequencies for driving and detection can be independently adjusted respectively. Therefore, for example, it is possible to avoid the inconvenience that the resonance frequency for detection is affected by adjustment for the resonance frequency for driving. - The shapes of the first and
second projections second projections main vibrator bodies 106. Alternatively, as shown in FIG. 25, the first andsecond projections main vibrator bodies 106. - The shape shown in FIG. 24 is advantageous in that the trimming treatment can be easily performed by means of, for example, laser beam scanning over the upper surface. In the case of the shape shown in FIG. 25, regions to be subjected to the trimming treatment are disposed over entire surfaces perpendicular to the direction of vibration of the respective two
vibrators - Actually, upon the adjustment for the resonance frequency, if the
first projections 132 are subjected to the trimming treatment in order to adjust the resonance frequency for driving, the resonance frequency for detection is considerably affected. However, even when thesecond projections 134 are subjected to the trimming treatment in order to adjust the resonance frequency for detection, the resonance frequency for driving is not affected. Therefore, when the resonance frequency is actually adjusted, it is preferable that the resonance frequency for driving is firstly adjusted by trimming-treating thefirst projections 132, and then the resonance frequency for detection is adjusted by trimming-treating thesecond projections 134. - Next, a vibration gyro sensor according to a seventeenth embodiment will be explained with reference to FIG. 26. Components or parts corresponding to those shown in FIG. 22 are designated by the same reference numerals, duplicate explanation of which will be omitted.
- As shown in FIG. 26, the vibration gyro sensor according to the seventeenth embodiment is constructed in approximately the same manner as the vibration gyro sensor according to the fifteenth embodiment. However, the former is different from the latter in that plate-shaped
driving sections 114 of the driving means 122 are arranged on lines for connecting centers of gravity of the respectivemain vibrator bodies 106 respectively. - In this embodiment, the respective two
vibrators sections 114 disposed in the vicinity of the connecting sections 108 (for example, the vibration gyro sensor according to the fifteenth embodiment). Accordingly, this embodiment is advantageous in that the detection sensitivity in the detectingsections 124 can be improved. - The adjustment for the resonance frequency by means of the trimming treatment for the vibration gyro sensor may be performed in another way, in place of the trimming treatment for the first and
second projections sections 114 provided between the respectivemain vibrator bodies 106, and the plate-shapedsections 116 of the detectingsections 124 provided between thesupport base 100 and theframe 104 are allowed to have wide widths respectively beforehand. The widths of the drivingsections 114 and the plate-shapedsections 116 are appropriately changed. Thus the resonance frequencies for driving and detection may be adjusted. - In this adjustment method, the resonance frequencies for driving and detection are not adjusted by changing the masses of the
main vibrator bodies 106 and thesupport base 100, but the resonance frequencies for driving and detection are adjusted by changing spring constants of the drivingsections 114 and the plate-shapedsections 116. - Specifically, when the frequency for driving is changed, the two plate-shaped
driving sections 114 disposed between the respectivemain vibrator bodies 106 are excised by means of, for example, laser machining or ultrasonic machining. When the frequency for detection is changed, the four plate-shapedsections 116 disposed between thesupport base 100 and theframe 104 are excised by means of, for example, laser machining or ultrasonic machining. - In this embodiment, it is unnecessary to form the
first projections 132 and thesecond projections 134 at the free ends of the respectivemain vibrator bodies 106 and at the both ends of thesupport base 100 in the longitudinal direction respectively. Accordingly, the production steps can be simplified. Moreover, the resonance frequency is easily adjusted because the region subjected to the trimming treatment is thin-walled. Unlike the method in which the resonance frequency is adjusted by changing the mass, the method of this embodiment is also advantageous in that the resonance frequency for driving and the resonance frequency for detection can be adjusted completely-independently from each other. - The fifteenth to seventeenth embodiments are illustrative of the formation of the
driving section 114 between themain vibrator bodies 106. Besides, thedriving section 114 may be formed between thesupport base 100 and themain vibrator body 106. Several examples of this arrangement are shown in FIGS. 28 and 29 as eighteenth and nineteenth embodiments. - Namely, as shown in FIG. 28, a vibration gyro sensor according to the eighteenth embodiment comprises driving
sections 114 each of which is formed between asupport base 100 and a portion of an end surface of amain vibrator body 106 disposed on a side of thesupport base 100 in the vicinity of aframe 104. As shown in FIG. 29, a vibration gyro sensor according to the nineteenth embodiment comprises drivingsections 114 each of which is formed between asupport base 100 and a portion corresponding to a region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction. - In both of the vibration gyro sensors according to the eighteenth and nineteenth embodiments, the
driving section 114 is not formed between the adjacentmain vibrator bodies 106. Accordingly, it is possible to narrow the spacing distance between the adjacentmain vibrator bodies 106, making it possible to facilitate realization of a compact size of the vibration gyro sensor. - In the fifteenth to nineteenth embodiments, the connecting
section 108, which is formed between each of themain vibrator bodies 106 and thesupport base 100, is disposed at the position on each of themain vibrator bodies 106, the position being located at the central portion of the end surface of themain vibrator body 106 on the side of thesupport base 100. However, it is not necessarily indispensable that the position is the central portion. For example, as shown in FIG. 30, the position, at which the connectingsection 108 is formed on each of themain vibrator bodies 106, may be disposed at a portion of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the frame 106 (twentieth embodiment). Although not shown, the position may be a portion corresponding to a region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction. - As shown in FIGS.31 to 33, in order to maintain constant vibration of the
driving section 114 effected by the driving piezoelectric/electrostrictive element 118 of the driving means 122, it is also preferable to adopt a mechanism wherein a signal, which is obtained from a reference piezoelectric/electrostrictive element 142 of a reference means 140 provided at a position different from that for the driving means 122, is fed to the driving means 122 in a feedback manner. - Namely, a vibration gyro sensor according to a twenty-first embodiment shown in FIG. 31 is constructed such that the vibration gyro sensor according to the seventeenth embodiment shown in FIG. 26 further comprises reference means140 provided in the vicinity of the connecting
sections 108 of the respectivemain vibrator bodies 106. The reference means 140 is constructed in approximately the same manner as the driving means 122, comprising a plate-shaped reference section (fourth plate-shaped section) 144 which is thin-walled in the direction of height, and a reference piezoelectric/electrostrictive element 142 formed on thereference section 144. Thereference section 144 is formed of ceramics in an integrated manner in the same manner as thedriving section 114. - A signal, which is obtained from the reference piezoelectric/
electrostrictive element 142 of the reference means 140, is fed to the driving piezoelectric/electrostrictive element 118 in the feedback manner to give constant vibration of the driving means 122 formed on the line for connecting the centers of gravity of the respectivemain vibrator bodies 106. - In the embodiment described above, the plate-shaped section provided on the line for connecting the centers of gravity of the respective
main vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122, and the plate-shaped section provided in the vicinity of the connectingsection 108 of each of themain vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140. However, it is allowable to adopt an arrangement in which the driving means 122 and the reference means 140 are disposed in an inverse manner. - Next, a vibration gyro sensor according to a twenty-second embodiment shown in FIG. 32 is constructed such that the vibration gyro sensor according to the eighteenth embodiment shown in FIG. 28 further comprises reference means140 provided between the
support base 100 and a portion corresponding to a region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction. - A signal, which is obtained from a reference piezoelectric/
electrostrictive element 142 of, the reference means 140, is fed to the driving piezoelectric/electrostrictive element 118 in a feedback manner to give constant vibration of the driving means 122 provided between thesupport base 100 and a portion of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of theframe 104. - In the embodiment described above, the plate-shaped section provided between the support-
base 100 and the portion of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of theframe 104 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122, and the plate-shaped section provided between thesupport base 100 and the portion corresponding to the region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140. However, it is allowable to adopt an arrangement in which the driving means 122 and the reference means 140 are disposed in an inverse manner. - Next, a vibration gyro sensor according to a twenty-third embodiment shown in FIG. 33 is constructed such that the vibration gyro sensor according to the seventeenth embodiment shown in FIG. 26 further comprises a reference means140 provided between the
support base 100 and a portion corresponding to a region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction. - A signal, which is obtained from a reference piezoelectric/
electrostrictive element 142 of the reference means 140, is fed to the driving piezoelectric/electrostrictive element 118 in a feedback manner to give constant vibration of the driving means 122 formed on the line for connecting the centers of gravity of the respectivemain vibrator bodies 106. - In the embodiment described above, the plate-shaped section provided on the line for connecting the centers of gravity of the respective
main vibrator bodies 106 and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the driving means 122, and the plate-shaped section provided between thesupport base 100 and the portion corresponding to the region of the end surface of themain vibrator body 106 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction and the piezoelectric/electrostrictive element formed on the plate-shaped section are used as the reference means 140. However, it is allowable to adopt an arrangement in which the driving means 122 and the reference means 140 are disposed in an inverse manner. - Any of the vibration gyro sensors according to the first to twenty-third embodiments has the structure of the so-called forced vibration system in which the vibrator2 (or 102) is directly vibrated by the driving section. However, as shown in FIGS. 34 to 36, it is allowable to adopt structures based on the free vibration system.
- At first, a vibration gyro sensor according to a twenty-fourth embodiment shown in FIG. 34 will be described. This vibration gyro sensor is illustrative of a structure comprising plate-shaped vibration-applying sections (fifth plate-shaped sections)150 arranged between a
support base 100 and respectivemain vibrator bodies 106 and extending in parallel to the longitudinal direction of thesupport base 100, thin-walled plate-shaped first connecting sections (sixth plate-shaped sections) 152 for connecting thesupport base 100 and the vibration-applyingsections 150, thin-walled plate-shaped connecting sections (seventh plate-shaped sections) 154 for connecting themain vibrator bodies 106 and the vibration-applyingsections 150, and driving means 122 provided between the respective vibration-applyingsections 150. - The first and second connecting
sections sections 108 of the vibration gyro sensors according to the fifteenth to twenty-third embodiments described above. The height of the vibration-applyingsection 150 is approximately the same as that of themain vibrator body 106. The width of the vibration-applyingsection 150 is designed to be smaller than the width of themain vibrator body 106 and slightly larger than those of the first and second connectingsections - A vibration gyro sensor according to a twenty-fifth embodiment shown in FIG. 35 is constructed in approximately the same manner as the vibration gyro sensor according to the twenty-fourth embodiment. However, the former is different from the latter in that the driving means122 is provided between the
support base 10 and a portion of the end surface of the vibration-applyingsection 150 on the side of thesupport base 100 in the vicinity of theframe 104. - A vibration gyro sensor according to a twenty-sixth embodiment shown in FIG. 36 is constructed in approximately the same manner as the vibration gyro sensor according to the twenty-fourth embodiment. However, the former is different from the latter in that the driving means122 is provided between the
support base 10 and a portion corresponding to a region of the end surface of the vibration-applyingsection 150 on the side of thesupport base 100 in the vicinity of the center of thesupport base 100 in the longitudinal direction. - In the vibration gyro sensors according to the twenty-fourth to twenty-sixth embodiments, the
vibrators 102A to 102D are indirectly vibrated by giving vibration to the vibration-applyingsections 150 disposed between themain vibrator bodies 106 and thesupport base 100 by the aid of the driving means 122. These vibration gyro sensors are advantageous in the following points because themain vibrator bodies 106 are scarcely affected by the drivingsections 114. Namely, (1) it is easy to obtain large amplitude when thevibrators 102A to 102D are vibrated, and (2) the vibration waveform scarcely suffers disturbance in thevibrators 102A to 102D, and it is possible to obtain a vibration waveform following the regular sine wave. - Vibration gyro sensors, which have been hitherto used, employ the elinvar alloy for the vibrator in many cases, in which the bulky piezoelectric/electrostrictive element formed with the electrodes is fixed to the vibrator by means of adhesion. Therefore, it is necessary to use, for example, solder or Ag paste for connecting external wiring to the electrodes of the piezoelectric/electrostrictive element. In this procedure, for example, the solder, the Ag paste, and the external wiring itself behave as added weights which greatly affect the vibration characteristics of the vibrator, making it difficult to produce the vibration gyro sensors.
- Vibration gyro sensors of another type is also known, in which a piezoelectric ceramic is used for the vibrator. However, such vibration gyro sensors are not essentially different from the foregoing conventional vibration gyro sensors in that the lead wire is connected to the part which is used to make vibration. Problems arise in that (a) the connecting section to the external wiring is less reliable, and (b) the dispersion in production is large.
- On the contrary, the vibration gyro sensors according to the first to twenty-sixth embodiments described above are advantageous in that external wiring can be easily connected to the pair of electrodes of the respective piezoelectric/
electrostrictive elements - This advantage will be explained on the basis of the vibration gyro sensor according to the seventeenth embodiment shown in FIG. 26. As shown in FIG. 37, the vibration gyro sensor is constructed by the integrated fired product made of ceramics (non-conductive materials) except for the respective pairs of electrodes of the driving means122 and the detecting
sections 124. Accordingly, the pair of electrodes for constructing the piezoelectric/electrostrictive element 118 of the driving means 122, two external wirings (160, 162) and (164, 166) led from the pair of electrodes, the pair of electrodes for constructing the piezoelectric/electrostrictive element 120 of the detectingsection 124, and two external wirings (168, 170), (172, 174), (176, 178) and (180, 182) led from the pair of electrodes can be formed with an identical wiring material in accordance with the film formation method respectively. - The wiring formation pattern will be specifically explained below. The two wirings (160, 162) and (164, 166) which are led from the pairs of electrodes for constructing the piezoelectric/
electrostrictive elements 118 of the driving means 122 provided between the respectivemain vibrator bodies 106, are formed such that they are led to theframe 104 via the upper surfaces of themain vibrator bodies 106 adjacent to the respective electrodes, the upper surfaces of the connectingsections 108, the upper surface of thesupport base 100, and the upper surfaces of the plate-shapedsections 116 of the detectingsections 124 adjacent to thevibrators - The two wirings (168, 170), (172, 174), (176, 178) and (180, 182) which are led from the pairs of electrodes of the piezoelectric/
electrostrictive elements 120 of the respective detectingsections 124 are formed such that they are led to theframe 104 from the respective detectingsections 124. - As described above, the material for constructing the electrodes and the wirings is not specifically limited provided that the material is a conductor which can withstand the oxidizable atmosphere at a high temperature of a degree of the heat treatment temperature and the firing temperature. For example, the material may be a simple substance of metal or an alloy. The material may be a mixture of a metal or an alloy and an additive such as an insulative ceramic and glass. Further, no problem occurs when the material is a conductive ceramic. More appropriately, it is preferable to use electrode materials comprising major components of high melting point noble metals such as platinum, palladium, and rhodium, and alloys such as silver-palladium, silver-platinum, and platinum-palladium.
- As for the method for forming the electrodes and the wirings, it is possible to appropriately adopt, for example, thick film methods such as screen printing, application methods such as dipping, and thin film methods such as ion beam, sputtering, vacuum vapor deposition, ion plating, CVD, and plating. However, there is no limitation thereto.
- Next, other embodiments will be further explained. The embodiments described below may be grasped as modified embodiments of the various embodiments shown in FIGS.1 to 21. Accordingly, components or parts corresponding to those shown in FIGS. 1 to 21 are designated by the same reference numerals, duplicate explanation of which will be omitted.
- At first, a vibration gyro sensor according to a twenty-seventh embodiment shown in FIG. 38 is constructed in approximately the same manner as the vibration gyro sensor according to the first embodiment shown in FIG. 1. However, the former is different from the latter in that a third plate-shaped
section 10, on which a driving piezoelectric/electrostrictive element 14 is provided, is formed in an integrated manner so that the two second plate-shapedsections 8 are bridged with the third plate-shapedsection 10. - A vibration gyro sensor according to a twenty-eighth embodiment shown in FIG. 39 is constructed in approximately the same manner as the vibration gyro sensor according to the third embodiment shown in FIG. 5. However, the former is different from the latter in that thin-walled third plate-shaped
sections 10 are formed in an integrated manner between thesupport bar 28 and the second plate-shapedsections 8 disposed at the right and left thereof, and driving piezoelectric/electrostrictive elements 14 are formed on the third plate-shapedsections 10 respectively so that the right and left twovibrators 2 are vibrated in an excited manner in mutually opposite directions by operating the driving piezoelectric/electrostrictive elements 14 respectively. - A vibration gyro sensor according to a twenty-ninth embodiment shown in FIG. 40 is constructed in approximately the same manner as the vibration gyro sensor according to the fifth embodiment shown in FIG. 7. However, the former is different from the latter in that thin-walled third plate-shaped
sections 10 are formed in an integrated manner between the two second plate-shapedsections 8 and sides of theattachment frame 30 opposing thereto, and driving piezoelectric/electrostrictive elements 14 are formed in an integrated manner on the third plate-shapedsections 10 in accordance with the film formation method. - A vibration gyro sensor according to a thirtieth embodiment shown in FIG. 41 is constructed in approximately the same manner as the vibration gyro sensor according to the seventh embodiment shown in FIG. 9. However, the former is different from the latter in that a thin-walled third plate-shaped
section 10 is formed in an integrated manner between the two second plate-shapedsections 8 disposed in theattachment frame 30 having the rectangular frame structure, and a driving piezoelectric/electrostrictive element 14 is formed in an integrated manner on the third plate-shapedsection 10 in accordance with the film formation method. - The vibration gyro sensors according to the twenty-seventh to thirtieth embodiments are constructed such that the
vibrators 2 are not driven directly, but the second plate-shapedsections 8 are driven. Accordingly, thevibrators 2 can make vibration without being restricted by the third plate-shapedsection 10 which constructs the driving means 122. Therefore, Q factor of thevibrator 2 is increased, and hence the vibration is not readily attenuated. Thus it is easy to handle the detection signal detected by the detecting piezoelectric/electrostrictive element 12. Further, the amplitude of vibration of thevibrator 2 is increased, and it is possible to further improve the sensitivity. - In the vibration gyro sensors according to the first to thirtieth embodiments, the first plate-shaped
section 6 for constructing the detecting section is formed to be more thin-walled than thevibrator 2, and they are integrated with each other in structure. However, in view of the function, the first plate-shapedsection 6 or the detecting section is constructed distinctly from thevibrator 2. - The following various embodiments are constructed such that the
vibrator 2 and the detecting section are integrated with each other both in structure and function. Such embodiments are more advantageous in order to improve the sensitivity. Explanation for such embodiments will be made in an specified manner below. Components or parts corresponding to those shown in FIGS. 1 to 21 are designated by the same reference numerals, duplicate explanation of which will be omitted. - At first, a vibration gyro sensor according to a thirty-first embodiment shown in FIG. 42 is constructed in an integrated manner by using an integrated fired product made of ceramics to have a structure comprising a rectangular block-shaped
support base 4 having a predetermined thickness, two second plate-shapedsections 8 which extend from proximal ends on a longitudinal side surface of thesupport base 4 in a direction perpendicular to the longitudinal side surface of thesupport base 4 while being separated from each other by a predetermined spacing distance, two first plate-shapedsections 6 each having an approximately strip-shaped (wide and lengthy) planar configuration which extend from proximal ends on upper portions of free ends of the respective second plate-shapedsections 8 in the direction perpendicular to the longitudinal side surface of thesupport base 4 while being separated from each other by a predetermined spacing distance (see FIG. 43), and a third plate-shapedsection 10 having an approximately strip-shaped planar configuration formed to bridge the two second plate-shapedsections 8 therewith. In this embodiments,vibrators 2 are constructed by the first plate-shapedsections 6. - The width of the second plate-shaped
section 8 is thinner than the width of the first plate-shapedsection 6. The second plate-shapedsection 8 is a thin-walled plate-shaped section having a principal surface which extends in the direction perpendicular to the first plate-shapedsection 6. The first plate-shaped section 6 (vibrator 2) is connected in an integrated manner to thesupport base 4 via the second plate-shapedsection 8. - The third plate-shaped
section 10 is connected in an integrated manner between portions of the second plate-shapedsections 8 in the vicinity of thesupport base 4. - In the vibration gyro sensor according to the thirty-first embodiment, detecting piezoelectric/
electrostrictive elements 12 are formed on approximately entire surfaces of upper surfaces of the respective first plate-shapedsections 6 which are formed to be wide. A driving piezoelectric/electrostrictive element 14 is formed on an approximately entire surface of an upper surface of the third plate-shapedsection 10. - In the vibration gyro sensor according to the thirty-first embodiment, the
vibrator 2 is constructed by the wide and lengthy first plate-shapedsection 6. Accordingly, thevibrator 2 has a large mass and a large moment. As a result, the velocity (∝ amplitude) brought about by the driving vibration is increased. Therefore, it is possible to further improve the sensitivity. Further, the detecting piezoelectric/electrostrictive element 12 is formed on the approximately entire surface of the first plate-shapedsection 6. Therefore, it is possible to accumulate a large amount of electric charge, and thus this embodiment is advantageous in the current detection system. - A vibration gyro sensor according to a thirty-second embodiment shown in FIG. 44 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment (see FIG. 42). However, the former is different from the latter in that thick-
walled block sections 70 are formed in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42, the first plate-shaped
section 6 is directly formed on the second plate-shapedsection 8. Therefore, it is feared that the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8 may be disadvantageous from a viewpoint of strength. However, in the vibration gyro sensor according to the thirty-second embodiment, the presence of theblock section 70 makes it possible to increase the strength of the boundary portion. Accordingly, this embodiment is advantageous to improve the reliability. - Next, a vibration gyro sensor according to a thirty-third embodiment shown in FIG. 45 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42. However, the former is different from the latter in that the
support base 4 is provided as arectangular frame 32. Two second plate-shapedsections 8 are formed in an integrated manner so that they extend from proximal ends disposed on one short side of inner frame wall surfaces of theframe 32 in a direction parallel to long sides of theframe 32 while being separated from each other by a predetermined spacing distance. - For example, the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42 includes the block-shaped
support base 4. Therefore, such a vibration gyro sensor suffers a problem concerning installation in that when thesupport base 4 is installed and fixed by using an adhesive or the like, the area for fixation is small, and it also suffers a problem concerning strength in that the rigidity of thesupport base 4 tends to be lowered, and the vibration is readily transmitted to the support bars 4. However, in this embodiment, thesupport base 4 is provided in the form of theframe 32, and thus the degree of freedom for attachment is increased. Further, the rigidity is also improved. Therefore, the foregoing problems can be solved, and hence this embodiment is practically appropriate. - Next, a vibration gyro sensor according to a thirty-fourth embodiment shown in FIG. 46 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-third embodiment (FIG. 45). However, the former is different from the latter in that thick-
walled block sections 70 are formed in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In this embodiment, the presence of the
block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8. Further, this embodiment is advantageous from viewpoints of installation and rigidity because theframe 32 is used. - Next, a vibration gyro sensor according to a thirty-fifth embodiment shown in FIG. 47 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-third embodiment (FIG. 45). However, the former is different from the latter in that a plurality of
recesses 72 are formed on the back surface of the first plate-shapedsection 6 as shown in FIG. 48, and detecting piezoelectric/electrostrictive elements 12 are formed in an array of islands at positions on the upper surface of the first plate-shapedsection 6 corresponding to the plurality ofrecesses 72. The embodiment shown in FIG. 47 is illustrative of a structure in which therecess 72 has a circular contour, and the detecting piezoelectric/electrostrictive element 12 has a circular planar configuration. - In the vibration gyro sensor according to the thirty-third embodiment, the strength is lowered at the portions of the first plate-shaped
section 6 on which therecesses 72 are formed. Therefore, when the first plate-shapedsection 6 is deformed by the Coriolis force, a strain, which is larger than that obtained at portions without having anyrecess 72, is generated at the portions on which therecesses 72 are formed. Accordingly, a large detection output can be obtained by forming the detecting piezoelectric/electrostrictive elements 12 at the portions corresponding to therecesses 72. Thus it is possible to further improve the sensitivity. - Next, a vibration gyro sensor according to a thirty-sixth embodiment shown in FIG. 49 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47. However, the former is different from the latter in that thick-
walled block sections 70 are provided in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In this embodiment, the presence of the
block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8. Further, this embodiment is advantageous from viewpoints of high reliability and improvement in sensitivity, because a large output can be obtained. - The vibration gyro sensors according to the thirty-fifth and thirty-sixth embodiments described above are illustrative of the structure in which the detecting piezoelectric/
electrostrictive elements 12 each having the approximately circular planar configuration are formed in the array of islands on the upper surface of the first plate-shapedsection 6. Alternatively, as shown in FIGS. 50 and 51, both of the contour of each of the recesses 72 (see FIG. 48) and the detecting piezoelectric/electrostrictive elements 12 may be square or rectangular (thirty-seventh and thirty-eighth embodiments). Those conceivable as the planar configuration of therecess 72 and the detecting piezoelectric/electrostrictive element 12 include, for example, circular and rectangular configurations as described above, as well as rhombic configurations. The shape of these components is not specifically limited. - Next, a vibration gyro sensor according to a thirty-ninth embodiment shown in FIG. 52 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-first embodiment shown in FIG. 42. However, the former is different from the latter in that an
attachment section 74 for fixing thesupport base 4 is provided in an integrated manner on a surface of thesupport base 4 opposite to the surface on which the second plate-shapedsections 8 are formed, and a support section (fifth plate-shaped section) 76, which is thin-walled in the widthwise direction of thesupport base 4, is provided in an integrated manner between thesupport base 4 and theattachment section 74. - Namely, the vibration gyro sensor according to the thirty-ninth embodiment has a structure in which a
tuning fork 78 is constructed by thesupport base 4, the two second plate-shapedsections 8, and the two vibrators 2 (first plate-shaped sections 6), and thetuning fork 78 is connected in an integrated manner to theattachment section 74 via the support section (fifth plate-shaped section) 76. - In general, the mode, which is obtained when the
tuning fork 78 is supported by an arbitrary fixing means with a support rod and thetuning fork 78 is vibrated, includes a mode in which the twovibrators 2 of thetuning fork 78 are vibrated in mutually opposite directions, and a mode in which the twovibrators 2 are vibrated in an identical direction respectively. - The mode, which is required for the vibration gyro sensor, is the former mode (the mode of vibration in mutually opposite directions). The latter mode is an unnecessary mode for the vibration gyro sensor. Accordingly, when the frequency of the necessary mode is greatly different from the frequency of the unnecessary mode, they can be easily discriminated from each other, and the detection accuracy in the necessary mode can be improved.
- FIG. 53 shows how the frequency in the necessary mode and the frequency in the unnecessary mode change depending on the length of the support rod. In FIG. 53, a curve “a” indicates a characteristic of the necessary mode, and a curve “b” indicates a characteristic of the unnecessary mode. As understood from FIG. 53, when the length of the support rod is large, the frequencies in the both modes greatly differ. However, as the support rod becomes short, the frequencies in the both modes approach to one another, and it is difficult to discriminate the both from each other. Therefore, the short length is disadvantageous from a viewpoint of detection accuracy.
- On the contrary, in the vibration gyro sensor according to the thirty-ninth embodiment, the
support base 4 is connected in the integrated manner to theattachment section 74 via thesupport section 76. Therefore, thesupport section 76 functions as the support rod, making it possible to improve the detection accuracy. - Next, a vibration gyro sensor according to a fortieth embodiment shown in FIG. 54 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-ninth embodiment shown in FIG. 52. However, the former is different from the latter in that thick-
walled block sections 70 are provided in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In this embodiment, the presence of the
block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8. Moreover, the vibration gyro sensor has atuning fork 78 which is constructed in an integrated manner on thesupport section 76. Therefore, this embodiment is advantageous in order to improve the detection accuracy. - Next, a vibration gyro sensor according to a forty-first embodiment shown in FIG. 55 is constructed in approximately the same manner as the vibration gyro sensor according to the thirty-ninth embodiment shown in FIG. 52. However, the former is different from the latter in that the
attachment section 76 has a form of a rectangular frame (hereinafter referred to as “attachment frame 80”). Thesupport section 76 is formed in an integrated manner so that it extends from its proximal end disposed on one short side of inner frame wall surfaces of theattachment frame 80 in a direction parallel to long sides of theattachment frame 80. - In this embodiment, it is possible to improve the detection accuracy. This embodiment is practically preferred from viewpoints of, for example, the degree of freedom for attachment and rigidity, because the attachment section is provided in the form of the
attachment frame 80. - Next, a vibration gyro sensor according to a forty-second embodiment shown in FIG. 56 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-first embodiment shown in FIG. 55. However, the former is different from the latter in that thick-
walled block sections 70 are provided in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In this embodiment, the presence of the
block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8. Moreover, this embodiment is advantageous from viewpoints of installation and rigidity, because theattachment frame 80 is used. - Next, a vibration gyro sensor according to a forty-third embodiment shown in FIG. 57 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-first embodiment shown in FIG. 55. However, the former is different from the latter in that a plurality of
recesses 72 are formed on the back surface of the first plate-shapedsection 6 as shown in FIG. 48, and detecting piezoelectric/electrostrictive elements 12 are formed in an array of islands at positions on the upper surface of the first plate-shapedsection 6 corresponding to the plurality ofrecesses 72. The embodiment shown in FIG. 57 is illustrative of a structure in which therecess 72 has a circular contour, and the detecting piezoelectric/electrostrictive element 12 has a circular planar configuration. - In this embodiment, it is possible to improve the detection accuracy, and a large detection output can be obtained. Thus it is possible to improve the sensitivity.
- Next, a vibration gyro sensor according to a forty-fourth embodiment shown in FIG. 58 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-third embodiment shown in FIG. 57. However, the former is different from the latter in that thick-
walled block sections 70 are provided in an integrated manner between the first plate-shapedsections 6 and the second plate-shapedsections 8 respectively. - In this embodiment, the presence of the
block section 70 makes it possible to increase the strength of the boundary portion between the first plate-shapedsection 6 and the second plate-shapedsection 8. Moreover, a large output can be obtained. Accordingly, this embodiment is advantageous in view of high reliability and improvement in sensitivity. - The vibration gyro sensors according to the forty-third and forty-fourth embodiments described above are illustrative of the structure in which the detecting piezoelectric/
electrostrictive elements 12 each having the approximately circular planar configuration are formed in the array of islands on the upper surface of the first plate-shapedsection 6. Alternatively, as shown in FIGS. 59 and 60, both of the contour of each of the recesses 72 (see FIG. 48) and the detecting piezoelectric/electrostrictive elements 12 may be square or rectangular (forty-fifth and forty-sixth embodiments). In these embodiments, those conceivable as the planar configuration of therecess 72 and the detecting piezoelectric/electrostrictive element 72 also include, for example, circular and rectangular configurations as described above, as well as rhombic configurations. The shape of these components is not specifically limited. - In the vibration gyro sensors according to the thirty-first to forty-sixth embodiments, the driving means122, which has the driving section (third plate-shaped section) 10 with the driving piezoelectric/
electrostrictive element 14 formed on its upper surface, is provided in the integrated manner between the second plate-shapedsections 8. Alternatively, as shown in FIG. 61, it is preferable to adopt a mechanism wherein a signal, which is obtained from a reference means 140 disposed at a position different from that of the drivingsection 10, is fed to the driving means 122 in a feedback manner in order to maintain constant vibration of thevibrators 2. - Namely, a vibration gyro sensor according to a forty-seventh embodiment shown in FIG. 61 has such a structure that the vibration gyro sensor according to the thirty-fourth embodiment (see FIG. 46) further comprises the reference means140 which is provided in parallel to the driving means 122 between the two second plate-shaped
sections 8. - The reference means140 is constructed in approximately the same manner as the driving means 122, comprising a plate-shaped reference section (fourth plate-shaped section) 144 which is thin-walled in its direction of height, and a reference piezoelectric/
electrostrictive element 142 formed on thereference section 144. Thereference section 144 is integrally formed of ceramics in the same manner as the drivingsection 10. Thereference section 144 and the drivingsection 10 are arranged in accordance with the following relation. Namely, the drivingsection 10 is formed in an integrated manner at a position close to theframe 80 between the second plate-shapedsections 8. Thereference section 144 is formed in an integrated manner at a position slightly nearer to the first plate-shapedsections 6 as compared with the drivingsection 10. - The signal, which is obtained from the reference piezoelectric/
electrostrictive element 142 of the reference means 140, is fed to the driving piezoelectric/electrostrictive element 14 in the feedback manner to give constant vibration of the driving means 122 formed between the second plate-shapedsections 8. - As shown in FIG. 62, the driving signal is supplied to the driving means122 via
lead wires 200 a, 200 b connected to upper and lower electrodes (not shown) formed on upper and lower surfaces of the driving piezoelectric/electrostrictive element 14. The reference signal is obtained from the reference means 140 vialead wires electrostrictive element 142. - The detection signal is obtained from the detecting piezoelectric/
electrostrictive element 12 formed on the first plate-shapedsection 6 vialead wires electrostrictive element 12. - Other embodiments, in which the reference means140 is formed, will be explained below. At first, a vibration gyro sensor according to a forty-eighth embodiment shown in FIG. 63 has such a structure that the vibration gyro sensor according to the thirty-sixth embodiment shown in FIG. 49 further comprises a reference means 140 which is provided in parallel to the driving means 122 between the two second plate-shaped
sections 8. - This embodiment is constructed as follows as shown in FIG. 64. Namely, the respective upper electrodes of the plurality of detecting piezoelectric/
electrostrictive elements 12 formed in the array of islands are electrically connected to leadwires 204 a via mediatingconductors 206 a respectively. The respective lower electrodes of the plurality of detecting piezoelectric/electrostrictive elements 12 are electrically connected to leadwires 204 b via mediatingconductors 206 b respectively. The detection signal is obtained from the detecting piezoelectric/electrostrictive elements 12 via thelead wires - Next, a vibration gyro sensor according to a forty-ninth embodiment shown in FIG. 65 is constructed as follows, based on the vibration gyro sensor according to the thirty-ninth embodiment (see FIG. 52). Namely, a mediating section (sixth plate-shaped section)208 having a free end is provided in an integrated manner at an approximately central portion of a side surface of the
support base 4 facing to thevibrators 2. A driving means 122 is provided in an integrated manner between the mediatingsection 208 and one of the second plate-shapedsections 8. A reference means 140 as described above is provided in an integrated manner between the mediatingsection 208 and the other second plate-shapedsection 8. - This embodiment is based on the use of the following feature. Namely, the support section76 (fifth plate-shaped section) is formed between the
support base 4 and theattachment section 74 so that thesupport section 76 is disposed at a position which is approximately coincides with the position of line symmetry of thetuning fork 78. Accordingly, when one of the two second plate-shapedsections 8 is vibrated to vibrate thecorresponding vibrator 2, theother vibrator 2 is vibrated at an identical frequency. - Therefore, when one of the
vibrators 2 is vibrated by operating the driving means 122, theother vibrator 2 is also vibrated at an identical frequency. Therefore, a signal obtained by the reference means 140 may be used to perform feedback control so that the vibration of the driving means 122 is constant. - Next, a vibration gyro sensor according to a fiftieth embodiment shown in FIG. 66 is constructed as follows, based on the vibration gyro sensor according to the thirty-ninth embodiment (see FIG. 52). Namely, a plurality of mediating
sections support base 4 facing to thevibrators 2. A driving means 122 is provided in an integrated manner between one of the second plate-shapedsections 8 and one of the mediatingsections 210 a. A reference means 140 is provided in an integrated manner between the other second plate-shapedsection 8 and theother mediating section 210 b. - In this embodiment, when one of the
vibrators 2 is vibrated by operating the driving means 122, theother vibrator 2 is also vibrated at an identical frequency in the same manner as described above. Therefore, a signal obtained by the reference means 140 may be used to perform feedback control so that the vibration of the driving means 122 is constant. - The vibration gyro sensors according to the forty-ninth and fiftieth embodiments have the structure in which the
tuning fork 78 is provided in the integrated manner on the block-shapedattachment section 74. Alternatively, theattachment section 74 is provided as a rectangular frame (attachment frame) 80, as exemplified by vibration gyro sensors according to fifty-first and fifty-second embodiments shown in FIGS. 67 and 68. - In these embodiments, the reference means140 may be used to perform feedback control so that the vibration effected by the driving means 122 is constant. Further, these embodiments are advantageous from viewpoints of, for example, the degree of freedom for attachment and rigidity, because the attachment section is provided as the
attachment frame 80. - Next, a vibration gyro sensor according to a fifty-third embodiment shown in FIG. 69 is constructed in approximately the same manner as the vibration gyro sensor according to the forty-second embodiment shown in FIG. 56. However, the former is different from the latter in that the
support section 76 is constructed as follows. - Namely, the
support section 76 comprises afirst support section 212 provided in an integrated and bridged manner to bridge a pair of inner wall surfaces of inner wall surfaces of theattachment frame 80 along the extending direction of thevibrators 2 so that thevibrators 2 are disposed thereover as shown in FIGS. 70A and 70C, and asecond support section 214 provided in an integrated and bridged manner to bridge thefirst support section 212 and thesupport base 4 so that the driving means 122 is disposed thereover as shown in FIG. 70B. - As described above, when the support rod for the
tuning fork 78 is elongated, it is possible to more clearly discriminate the necessary mode from the unnecessary mode. Accordingly, the elongation of the support rod for thetuning fork 78 is preferred in order to improve the detection accuracy of the sensor. However, the vibration gyro sensor according to the forty-second embodiment (see FIG. 56) has the structure in which thesupport section 76 constructed by the fifth plate-shaped section is provided in the integrated manner between thesupport base 4 and theattachment frame 80. Therefore, if thesupport section 76 is elongated, the entire length of the sensor is also elongated in accordance therewith. Accordingly, the elongation of thesupport section 76 is limited. - On the contrary, in the vibration gyro sensor according to the fifty-third embodiment, the
second support section 214, which functions in substantially the same manner as the support rod for thetuning fork 78, is provided in parallel to the two second plate-shapedsections 8, giving the structure in which thesecond support section 214 extends in the same direction as the second plate-shapedsections 8. Therefore, even when the length of thesecond support section 214 is elongated, the entire length of the sensor is not changed until the length of thesecond support section 214 exceeds a certain range. Accordingly, thesecond support section 214 can be elongated, and it is possible to realize further improvement in detection accuracy. - Besides, the foregoing structure of the first and
second support sections - The vibration gyro sensor according to a fifty-fourth embodiment shown in FIG. 71 is constructed such that the first and
second support sections support section 76 of the vibration gyro sensor according to the fifty-first embodiment shown in FIG. 67. The vibration gyro sensor according to a fifty-fifth embodiment shown in FIG. 72 is constructed such that the first andsecond support sections support section 76 of the vibration gyro sensor according to the fifty-second embodiment shown in FIG. 68. - The vibration gyro sensor constructed by the integrated fired product made of ceramics can be formed as the integrated stacked structure comprising the
thin plate layer 22, thesubstrate layer 24, and thespacer layer 26 as shown in FIG. 2. Alternatively, as shown in FIG. 73, the vibration gyro sensor can be constructed by using an additional layer (intermediate layer) 216 which is allowed to intervene between thethin plate layer 22 and thesubstrate layer 24. - The thickness of the
intermediate layer 216 is appropriately 1 μm to 500 μm, preferably 10 μm to 400 μm, and more preferably 50 μm to 300 μm. If the thickness exceeds 500 μm, it is difficult to make bending, and hence the sensitivity is lowered. If the thickness is thinner than 1 μm, the strength is low, and hence a problem arises in that theintermediate layer 216 tends to suffer breakage. Accordingly, it is preferable to adopt the foregoing range for the thickness of theintermediate layer 216. - The formation of the
intermediate layer 216 is preferred in order to ensure the strength and improve the sensitivity, concerning the vibration gyro sensors of the type in which the block-shapedvibrators 2 are supported by the thin-walled first plate-shaped sections 6 (see FIGS. 1, 4 to 18, and 38 to 41), and concerning the vibration gyro sensors of the type in which thesupport base 100 integrally provided with the four block-shapedvibrators 102A to 102D is supported by the thin-walled plate-shaped sections 116 (see FIGS. 22 and 24 to 37). - The intervention of the
intermediate layer 216 is also advantageous in order to ensure the strength and improve the sensitivity for those of the type in which thevibrator 2 is constructed by the thin-walled first plate-shapedsection 6, as in the vibration gyro sensors according to the thirty-first to fifty-fifth embodiments shown in FIGS. 42 to 72. Examples of such construction are shown in FIGS. 74 to 76. - An embodiment shown in FIG. 74 is illustrative of a structure in which the
intermediate layer 216 is allowed to intervene between thethin plate layer 22 and thesubstrate layer 24 for constructing the vibration gyro sensor according to the thirty-third embodiment shown in FIG. 45. Anupper surface portion 32 a of theframe 32,upper portions 6 a of the first plate-shapedsections 6,upper end portions 8 a of the second plate-shapedsections 8, and the third plate-shapedsection 10 are formed in an integrated manner by processing thethin plate layer 22. Anupper portion 32 b of theframe 32 except for the upper surface portion thereof,lower portions 6 b of the first plate-shapedsections 6, andupper portions 8 b of the second plate-shapedsections 8 except for the upper end portions thereof are formed in an integrated manner by processing theintermediate layer 216. A remainingportion 32 c of theframe 32 and remainingportions 8 c of the second plate-shapedsections 8 are formed in an integrated manner by processing thesubstrate layer 24. The layers are stacked and integrated with each other, followed by firing. Thus the vibration gyro sensor according to the thirty-third embodiment is produced. - An embodiment shown in FIG. 75 is illustrative of a structure in which the
intermediate layer 216 is allowed to intervene between thethin plate layer 22 and thesubstrate layer 24 for constructing the vibration gyro sensor according to the thirty-fourth embodiment shown in FIG. 46. Anupper surface portion 32 a of theframe 32,upper portions 6 a of the first plate-shapedsections 6,upper end portions 8 a of the second plate-shapedsections 8, and the third plate-shapedsection 10 are formed in an integrated manner by processing thethin plate layer 22. Anupper portion 32 b of theframe 32 except for the upper surface portion thereof,lower portions 6 b of the first plate-shapedsections 6, andupper portions 8 b of the second plate-shapedsections 8 except for the upper end portions thereof are formed in an integrated manner by processing theintermediate layer 216. A remainingportion 32 c of theframe 32, remainingportions 8 c of the second plate-shapedsections 8, and theblock sections 70 are formed in an integrated manner by processing thesubstrate layer 24. The layers are stacked and integrated with each other, followed by firing. Thus the vibration gyro sensor according to the thirty-fourth embodiment is produced. - An embodiment shown in FIG. 76 is illustrative of a structure in which the
intermediate layer 216 is allowed to intervene between thethin plate layer 22 and thesubstrate layer 24 for constructing the vibration gyro sensor according to the thirty-fifth embodiment shown in FIG. 47. Anupper surface portion 32 a of theframe 32,upper portions 6 a of the first plate-shapedsections 6,upper end portions 8 a of the second plate-shapedsections 8, and the third plate-shapedsection 10 are formed in an integrated manner by processing thethin plate layer 22. Anupper portion 32 b of theframe 32 except for the upper surface portion thereof,lower portions 6 b of the first plate-shapedsections 6 formed with a plurality of holes 218 (for constructing therecesses 72 shown in FIG. 48 together with the thin plate layer 22), andupper portions 8 b of the second plate-shapedsections 8 except for the upper end portions thereof are formed in an integrated manner by processing theintermediate layer 216. A remainingportion 32 c of theframe 32 and remainingportions 8 c of the second plate-shapedsections 8 are formed in an integrated manner by processing thesubstrate layer 24. The layers are stacked and integrated with each other, followed by firing. Thus - the vibration gyro sensor according to the thirty-fifth embodiment is produced.
- As described above, in the vibration gyro sensors according to the first to fifty-fifth embodiments, the vibrators2 (or 102), the support base 4 (or 100), the
attachment frame electrostrictive elements electrostrictive elements - In the respective embodiments of the illustrated vibration gyro sensors, the thin-walled second plate-shaped
sections 8 are depicted as those having the planar plate configuration in any case. However, the present invention is not limited to those having the planar plate configuration. It is allowable to use a structure in which the rigidity is lowered in order to easily vibrate the vibrators in their desired vibration directions. It is needless to say that no problem occurs at all when those having a partially constricted shape are used. - As clarified from the foregoing description, the vibration gyro sensor according to the present invention is constructed as a whole by the integrated fired product made of ceramics, and no magnetic material is used at all. Therefore, it is completely unnecessary to consider any influence exerted on the characteristics by the ambient magnetic field, and the vibration gyro sensor does not undergo any restriction concerning its installation place or the like. Further, the large displacement is obtained by using the first and second plate-shaped sections in the detecting and driving directions of the vibrators. Moreover, the vibration gyro sensor has the integrated structure in which the piezoelectric/electrostrictive element directly contacts with the vibrator. Accordingly, the large output is effectively obtained, and any cause to lower the sensitivity due to absorption of stress is effectively dissolved. Thus the highly sensitive sensor is advantageously provided.
- The combined sensor according to the present invention is different from the conventional sensor which has only one function for one element. The combined sensor makes it extremely easy to provide another sensor in the integrated manner adjacent to the vibration gyro sensor. For example, it is possible to easily realize the structure in which the vibration gyro sensor and the acceleration sensor are simultaneously provided as one element (integrated sensor).
Claims (64)
1. A vibration gyro sensor comprising at least one or more vibrators subjected to excited vibration effected by at least one or more driving means, a support base for supporting said vibrator at a proximal end thereof, and at least one or more detecting sections including at least one or more detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrator when said vibrator is rotated, said vibration gyro sensor including:
said detecting section composed of an integrated fired product made of ceramics together with said vibrator and said support base, said detecting section being constructed by a first plate-shaped section which is more thin-walled than said vibrator and which has a principal surface extending in said direction of vibration;
said detecting piezoelectric/electrostrictive element formed in an integrated manner on said first plate-shaped section in accordance with a film formation method; and
at least one or more thin-walled second plate-shaped sections for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being provided for said vibrator in an integrated manner so that a principal surface thereof extends in said direction perpendicular to said direction of vibration.
2. The vibration gyro sensor according to , wherein:
claim 1
said vibrator is provided with a thin-walled excisable section extending from a forward end thereof; and
a resonance frequency of said vibrator is adjusted in accordance with an amount of excision of said excisable section.
3. The vibration gyro sensor according to or , wherein two of said vibrators are supported in parallel to one another by said support base, and said two vibrators are vibrated by said driving means in an excited manner in mutually opposite directions.
claim 1
2
4. The vibration gyro sensor according to any one of to , wherein said driving means comprises:
claims 1
3
a third plate-shaped section which is more thin-walled than said vibrator and which is composed of said integrated fired product made of ceramics together with said vibrator; and
a driving piezoelectric/electrostrictive element formed in an integrated manner on said third plate-shaped section in accordance with said film formation method.
5. The vibration gyro sensor according or , wherein:
claim 3
4
a support bar is arranged at a position which is located between said two vibrators and which is separated from said vibrators; and
said support bar is supported in an integrated manner by said support base together with said two vibrators.
6. The vibration gyro sensor according to any one of to , wherein said support base is constructed by an attachment frame which is disposed outside said vibrator and separated therefrom by a predetermined distance so that said vibrator is surrounded thereby.
claims 1
5
7. The vibration gyro sensor according to any one of to , wherein said driving means is provided in an integrated manner between said two vibrators.
claims 3
6
8. The vibration gyro sensor according to any one of to , wherein said driving means is provided in an integrated manner between said second plate-shaped sections.
claims 3
6
9. The vibration gyro sensor according to , wherein said driving means are provided in an integrated manner between said support bar and said vibrators respectively.
claim 5
10. The vibration gyro sensor according to , wherein said driving means are provided in an integrated manner between said support bar and said second plate-shaped sections respectively.
claim 5
11. The vibration gyro sensor according to , wherein said driving means are provided in an integrated manner between said attachment frame and said vibrators respectively.
claim 6
12. The vibration gyro sensor according to , wherein said driving means are provided in an integrated manner between said attachment frame and said second plate-shaped sections respectively.
claim 6
13. A vibration gyro sensor comprising two vibrators arranged in parallel to one another and mutually subjected to excited vibration, a frame for surrounding said vibrators and supporting said vibrators at proximal ends thereof, and detecting sections including detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrators when said vibrators are rotated, said vibration gyro sensor including:
said detecting sections composed of an integrated fired product made of ceramics together with said vibrators and said frame, said detecting sections being constructed by first plate-shaped sections which are more thin-walled than said vibrators and which have principal surfaces extending in said direction of vibration;
said detecting piezoelectric/electrostrictive elements formed in an integrated manner on said first plate-shaped sections in accordance with a film formation method;
a thin-walled second plate-shaped section for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being formed in an integrated manner for a portion located between regions of said frame for supporting said two vibrators so that a principal surface thereof extends in said direction perpendicular to said direction of vibration;
a portion of said frame opposing to a region for forming said second plate-shaped section, said portion being a third plate-shaped section which is more thin-walled than said frame; and
a driving piezoelectric/electrostrictive element formed in an integrated manner on said third plate-shaped section in accordance with said film formation method, wherein:
said two vibrators are vibrated in an excited manner on the basis of vibration of said frame effected by said driving piezoelectric/electrostrictive element.
14. The vibration gyro sensor according to , wherein:
claim 13
each of said vibrators is provided with a thin-walled excisable section extending from a forward end thereof; and
a resonance frequency of said vibrator is adjusted in accordance with an amount of excision of said excisable section.
15. The vibration gyro sensor according to or , wherein an attachment section for fixing said frame is formed in an integrated manner on an outer surface of a region of said frame for forming said second plate-shaped section.
claim 13
14
16. The vibration gyro sensor according to , wherein said attachment section includes, in an integrated manner, an attachment frame which is positioned outside said frame and separated therefrom by a predetermined distance so that said frame is surrounded thereby.
claim 15
17. A vibration gyro sensor comprising two vibrators arranged in parallel to one another and mutually subjected to excited vibration, a support base for supporting said vibrators at proximal ends thereof, and detecting sections including detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrators when said vibrators are rotated, said vibration gyro sensor including:
said detecting sections composed of an integrated fired product made of ceramics together with said vibrators and said support base, said detecting sections being constructed by first plate-shaped sections which are more thin-walled than said vibrators and which have principal surfaces extending in said direction of vibration;
said detecting piezoelectric/electrostrictive elements formed in an integrated manner on said first plate-shaped sections in accordance with a film formation method;
a thin-walled second plate-shaped section for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being formed in an integrated manner for a portion located between regions of said support base for supporting said two vibrators so that a principal surface thereof extends in said direction perpendicular to said direction of vibration;
an attachment section provided with an attachment frame connected in an integrated manner to an outer surface of a region for forming said second plate-shaped section and disposed outside said two vibrators and said support base while being separated therefrom by predetermined distances so that said two vibrators and said support base are surrounded thereby;
third plate-shaped sections more thin-walled than said support base and formed in an integrated manner to bridge said attachment frame and portions of said support base located on both sides of said second plate-shaped section respectively; and
driving piezoelectric/electrostrictive elements formed in an integrated manner on said third plate-shaped sections in accordance with said film formation method, wherein:
said two vibrators are vibrated in an excited manner on the basis of vibration of said support base effected by said driving piezoelectric/electrostrictive elements.
18. The vibration gyro sensor according to , wherein:
claim 17
each of said vibrators is provided with a thin-walled excisable section extending from a forward end thereof; and
a resonance frequency of said vibrator is adjusted in accordance with an amount of excision of said excisable section.
19. A vibration gyro sensor comprising:
a vibrator having a major axis extending in a certain direction;
a support base extending in a direction perpendicular to said certain direction, for supporting said vibrator at an end thereof;
a frame for surrounding said vibrator and said support base, with a frame surface being parallel to a plane including said certain direction and said extending direction of said support base; and
a detecting section provided with a detecting piezoelectric/electrostrictive element attached between said support base and said frame, for detecting strain generated when said vibrator is rotated around an axis perpendicular to said plane, wherein:
all of said vibrator, said support base, and said detecting section are constructed by an integrated fired product made of ceramics;
said detecting section is constructed by a first plate-shaped section which is more thin-walled than said vibrator in its direction of height; and
said vibrator is supported by said support base at said end which is constructed by a second plate-shaped section which is thin-walled in said certain direction.
20. The vibration gyro sensor according to , wherein said detecting section is constructed by a ring member formed between said support base and said frame, and said first plate-shaped section provided in a bridged manner in said ring member in parallel to said extending direction of said support base.
claim 19
21. The vibration gyro sensor according to or , wherein at least two of said vibrators are supported by said support base in parallel to one another, and a driving means for vibrating said respective vibrators in an excited manner in mutually opposite directions is disposed.
claim 19
20
22. The vibration gyro sensor according to , wherein said driving means includes:
claim 21
a third plate-shaped section which is more thin-walled in its direction of height than said vibrator and which is constructed by said integrated fired product made of ceramics together with said vibrator; and
a driving piezoelectric/electrostrictive element formed on said third plate-shaped section.
23. The vibration gyro sensor according to or , wherein said driving means is provided in an integrated manner between said two vibrators.
claim 21
22
24. The vibration gyro sensor according to , wherein said driving means is arranged on a line for connecting respective centers of gravity of said both vibrators.
claim 23
25. The vibration gyro sensor according to or , wherein said driving means is provided in an integrated manner between said respective vibrators and said support base.
claim 21
22
26. The vibration gyro sensor according to any one of to , further comprising a reference means for performing feedback control so that said driving means makes constant vibration.
claims 21
25
27. The vibration gyro sensor according to , wherein said reference means comprises:
claim 26
a fourth plate-shaped section which is more thin-walled in its direction of height than said vibrator and which is constructed by said integrated fired product made of ceramics together with said vibrator; and
a reference piezoelectric/electrostrictive element formed on said fourth plate-shaped section.
28. The vibration gyro sensor according to or , wherein said reference means is provided in an integrated manner between said respective vibrators.
claim 26
27
29. The vibration gyro sensor according to or , wherein said reference means are provided in an integrated manner between said respective vibrators and said support base.
claim 26
27
30. The vibration gyro sensor according to any one of to , further comprising a vibration-applying section provided in an integrated manner between said vibrator and said support base.
claims 19
29
31. The vibration gyro sensor according to , wherein said vibration-applying section comprises:
claim 30
a fifth plate-shaped section arranged between said vibrator and said support base and extending in parallel to a longitudinal direction of said support base;
a sixth plate-shaped sections for connecting said support base to said fifth plate-shaped section; and
a seventh plate-shaped section for connecting said vibrator to said fifth plate-shaped section.
32. The vibration gyro sensor according to or , wherein said driving means is provided in an integrated manner between said respective vibration-applying sections.
claim 30
31
33. The vibration gyro sensor according to or , wherein said driving means is provided in an integrated manner between said vibration-applying section and said support base.
claim 30
31
34. The vibration gyro sensor according to any one of to , further comprising:
claims 19
33
thin-walled first projections for adjusting a resonance frequency for driving, possessed by said vibrator at free ends thereof; and
thin-walled second projections for adjusting a resonance frequency for detection, possessed by said support base at both ends thereof in its longitudinal direction, wherein:
said first and second projections are constructed by said integrated fired product made of ceramics together with said vibrator and said support base.
35. The vibration gyro sensor according to , wherein said first and second projections are thin-walled in a direction of height with respect to said vibrator.
claim 34
36. The vibration gyro sensor according to , wherein said first and second projections are thin-walled in said extending direction of said support base with respect to said vibrator.
claim 34
37. The vibration gyro sensor according to any one of to , wherein:
claims 22
36
said third plate-shaped section of said driving means is also used as an adjustment objective for a resonance frequency for driving; and
said first plate-shaped section of said detecting section is also used as an adjustment objective for a resonance frequency for detection.
38. A vibration gyro sensor comprising at least one or more vibrators subjected to excited vibration effected by a driving means, a support base for supporting said vibrator at a proximal end thereof, and at least one or more detecting sections including at least one or more detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrator when said vibrator is rotated, said vibration gyro sensor including:
said vibrator composed of an integrated fired product made of ceramics together with said support base, said vibrator being constructed by a first plate-shaped section which is more thin-walled than said support base and which has a principal surface extending in said direction of vibration;
said detecting section constructed by said first plate-shaped section and said detecting piezoelectric/electrostrictive element formed in an integrated manner on said first plate-shaped section in accordance with a film formation method; and
at least one or more thin-walled second plate-shaped sections for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being provided for said vibrator in an integrated manner so that a principal surface thereof extends in said direction perpendicular to said direction of vibration.
39. The vibration gyro sensor according to , wherein two of said vibrators are supported in parallel to one another by said support base, said driving means is arranged between said respective second plate-shaped sections, and said two vibrators are vibrated by said driving means in an excited manner in mutually opposite directions.
claim 38
40. The vibration gyro sensor according to or , wherein said driving means comprises:
claim 38
39
a third plate-shaped section which is more thin-walled than said support base and which is composed of said integrated fired product made of ceramics together with said second plate-shaped sections; and
a driving piezoelectric/electrostrictive element formed in an integrated manner on said third plate-shaped section in accordance with said film formation method.
41. The vibration gyro sensor according to any one of to , wherein said detecting piezoelectric/electrostrictive element is formed in an integrated manner on an approximately entire surface of said first plate-shaped section.
claims 38
40
42. The vibration gyro sensor according to any one of to , wherein:
claims 38
41
said first plate-shaped section has, on its back surface, a plurality of recesses; and
said detecting piezoelectric/electrostrictive elements are formed in an array of islands at positions on a front surface of said first plate-shaped section corresponding to said plurality of recesses.
43. The vibration gyro sensor according to any one of to , wherein a thick-walled block section is provided in an integrated manner between said first plate-shaped section and said second plate-shaped section.
claims 38
42
44. The vibration gyro sensor according to any one of to , wherein said support base is constructed by a frame which is positioned outside said vibrators and separated by predetermined distances so that said vibrators are surrounded thereby.
claims 38
43
45. The vibration gyro sensor according to any one of to , wherein said driving means is provided in an integrated manner between said respective second plate-shaped sections.
claims 38
44
46. The vibration gyro sensor according to or , wherein said driving means is provided in an integrated manner between said respective block sections.
claim 43
44
47. The vibration gyro sensor according to claim 44, wherein said driving means is provided in an integrated manner between said block section and said frame.
48. The vibration gyro sensor according to any one of to , further comprising a reference means for performing feedback control so that said vibration of said driving means is constant.
claims 38
47
49. The vibration gyro sensor according to , wherein said reference means comprises:
claim 48
a fourth plate-shaped section which is more thin-walled in its direction of height than said support base and which is constructed by said integrated fired product made of ceramics together with said vibrator; and
a reference piezoelectric/electrostrictive element formed on said fourth plate-shaped section.
50. The vibration gyro sensor according to or , wherein said reference means is provided in an integrated manner between said respective second plate-shaped sections.
claim 48
49
51. The vibration gyro sensor according to any one of to , wherein said driving means is provided in an integrated manner on one plate-shaped section of said respective second plate-shaped sections, and said reference means is provided on the other second plate-shaped section.
claims 48
50
52. The vibration gyro sensor according to , wherein:
claim 51
a mediating section having a free end is provided in an integrated manner at an approximately central portion of a side surface of said support base facing to said vibrating section;
said driving means is provided in an integrated manner between one of said second plate-shaped sections and said mediating section; and
said reference means is provided in an integrated manner between the other second plate-shaped section and said mediating section.
53. The vibration gyro sensor according to , wherein:
claim 51
a plurality of mediating sections each having a free end are provided in an integrated manner at positions of both ends in a widthwise direction of said support base facing to said vibrating sections;
said driving means is provided in an integrated manner between one of said second plate-shaped sections and one of said mediating sections; and
said reference means is provided in an integrated manner between the other second plate-shaped section and the other mediating section.
54. The vibration gyro sensor according to any one of to , wherein:
claims 38
53
an attachment section for fixing said support base is provided in an integrated manner on a surface opposite to a surface of said support base on which said second plate-shaped sections are formed;
a fifth plate-shaped section, which is thin-walled in a widthwise direction of said support base, is provided in an integrated manner between said support base and said attachment section; and
a tuning fork is constructed by at least said support base and said vibrators.
55. The vibration gyro sensor according to , wherein said attachment section is constructed by an attachment frame which is positioned outside said tuning fork and separated by predetermined distances therefrom so that said tuning fork is surrounded thereby.
claim 54
56. The vibration gyro sensor according to , wherein:
claim 55
a support section is provided in an integrated and bridged manner so that a pair of inner wall surfaces of said attachment frame, which extend along said extending direction of said vibrators, are bridged by said support section facing to said vibrators disposed thereover; and
said fifth plate-shaped section is provided in an integrated manner between said support section and said support base.
57. A combined sensor comprising a vibration gyro sensor and another sensor having a function different from that of said vibration gyro sensor; said vibration gyro sensor comprising at least one or more vibrators subjected to excited vibration effected by at least one or more driving means, a support base for supporting said vibrator at a proximal end thereof, at least one or more detecting sections including at least one or more detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrator when said vibrator is rotated, said detecting section composed of an integrated fired product made of ceramics together with said vibrator and said support base, said detecting section being constructed by a first plate-shaped section which is more thin-walled than said vibrator and which has a principal surface extending in said direction of vibration, said detecting piezoelectric/electrostrictive element formed in an integrated manner on said first plate-shaped section in accordance with a film formation method, at least one or more thin-walled second plate-shaped sections for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being provided for said vibrator in an integrated manner so that a principal surface thereof extends in said direction perpendicular to said direction of vibration, said support base constructed by an attachment frame positioned outside said vibrator and separated by predetermined spacing distances therefrom so that said vibrator is surrounded thereby, and said driving means provided in an integrated manner between said attachment frame and said vibrator; and said combined sensor further comprising a second attachment frame formed in an integrated manner with said attachment frame and provided adjacent to said attachment frame of said vibration gyro sensor; wherein said another sensor is supported in an integrated manner in said second attachment frame.
58. A combined sensor comprising a vibration gyro sensor and another sensor having a function different from that of said vibration gyro sensor; said vibration gyro sensor comprising two vibrators arranged in parallel to one another and mutually subjected to excited vibration, a frame for surrounding said vibrators and supporting said vibrators at proximal ends thereof, detecting sections including detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrators when said vibrators are rotated, said detecting sections composed of an integrated fired product made of ceramics together with said vibrators and said frame, said detecting sections being constructed by first plate-shaped sections which are more thin-walled than said vibrators and which have principal surfaces extending in said direction of vibration, said detecting piezoelectric/electrostrictive elements formed in an integrated manner on said first plate-shaped sections in accordance with a film formation method, a thin-walled second plate-shaped section for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being formed in an integrated manner for a portion located between regions of said frame for supporting said two vibrators so that a principal surface thereof extends in said direction perpendicular to said direction of vibration, a portion of said frame opposing to a region for forming said second plate-shaped section, said portion being a third plate-shaped section which is more thin-walled than said frame, a driving piezoelectric/electrostrictive element formed in an integrated manner on said third plate-shaped section in accordance with said film formation method, said two vibrators being vibrated in an excited manner on the basis of vibration of said frame effected by said driving piezoelectric/electrostrictive element, an attachment section provided for fixing said frame and formed in an integrated manner on an outer surface of said region for forming said second plate-shaped section, and an attachment frame provided in an integrated manner with said attachment section, said attachment frame being positioned outside said frame and separated by predetermined distances therefrom so that said frame is surrounded thereby; and said combined sensor further comprising a second attachment frame formed in an integrated manner with said attachment frame and provided adjacent to said attachment frame of said vibration gyro sensor; wherein said another sensor is supported in an integrated manner in said second attachment frame.
59. A combined sensor comprising a vibration gyro sensor and another sensor having a function different from that of said vibration gyro sensor; said vibration gyro sensor comprising two vibrators arranged in parallel to one another and mutually subjected to excited vibration, a support base for supporting said vibrators at proximal ends thereof, and detecting sections including detecting piezoelectric/electrostrictive elements for detecting displacement generated in a direction perpendicular to a direction of vibration of said vibrators when said vibrators are rotated, said vibration gyro sensor including:
said detecting sections composed of an integrated fired product made of ceramics together with said vibrators and said support base, said detecting sections being constructed by first plate-shaped sections which are more thin-walled than said vibrators and which have principal surfaces extending in said direction of vibration;
said detecting piezoelectric/electrostrictive elements formed in an integrated manner on said first plate-shaped sections in accordance with a film formation method;
a thin-walled second plate-shaped section for decreasing rigidity in said direction of vibration and facilitating said vibration, said second plate-shaped section being formed in an integrated manner for a portion located between regions of said support base for supporting said two vibrators so that a principal surface thereof extends in said direction perpendicular to said direction of vibration;
an attachment section provided with an attachment frame connected in an integrated manner to an outer surface of a region for forming said second plate-shaped section and disposed outside said two vibrators and said support base while being separated therefrom by predetermined distances so that said two vibrators and said support base are surrounded thereby;
third plate-shaped sections more thin-walled than said support base and formed in an integrated manner to bridge said attachment frame and portions of said support base located on both sides of said second plate-shaped section respectively; and
driving piezoelectric/electrostrictive elements formed in an integrated manner on said third plate-shaped sections in accordance with said film formation method;
said two vibrators being vibrated in an excited manner on the basis of vibration of said support base effected by said driving piezoelectric/electrostrictive elements; and said combined sensor further comprising a second attachment frame formed in an integrated manner with said attachment frame and provided adjacent to said attachment frame of said vibration gyro sensor; wherein said another sensor is supported in an integrated manner in said second attachment frame.
60. A method for producing a vibration gyro sensor, comprising the steps of:
stacking and integrating at least a substrate layer and a thin plate layer composed of green sheets, followed by firing to produce a fired product including, in an integrated manner, at least one or more vibrators each having a major axis extending in a certain direction, a support base extending in a direction perpendicular to said certain direction, for supporting said vibrator at one end, a frame having its frame surface parallel to a plane which includes said certain direction and said extending direction of said support base, for surrounding said vibrator and said support base, and at least one or more detecting sections attached between said support base and said frame;
forming at least one or more piezoelectric/electrostrictive elements on at least said detecting sections in accordance with a film formation method;
adjusting a resonance frequency for driving by applying a trimming treatment to a part of said vibrator; and
adjusting a resonance frequency for detection by applying a trimming treatment to a part of said support base.
61. The method according to , wherein:
claim 60
said vibration gyro sensor comprises at least two of said vibrators supported in parallel to one another by said support base, and a driving means provided between said two vibrators for vibrating said respective vibrators in an excited manner in mutually opposite directions; and
said driving means includes a plate-shaped section which is more thin-walled in its direction of height than said vibrators and which is composed of said integrated fired product made of ceramics together with said vibrators, and a driving piezoelectric/electrostrictive element formed on said plate-shaped section.
62. The method according to , wherein:
claim 60
said step for adjusting said resonance frequency for driving is performed by applying a trimming treatment to a thin-walled first projection protruding in an integrated manner from a free end of said vibrator; and
said step for adjusting said resonance frequency for detection is performed by applying a trimming treatment to thin-walled second projections protruding in an integrated manner from both ends of said support base in its longitudinal direction.
63. The method according to , wherein:
claim 60
said step for adjusting said resonance frequency for driving is performed by applying a trimming treatment to said plate-shaped section of said driving means in its widthwise direction; and
said step for adjusting said resonance frequency for detection is performed by applying a trimming treatment to a plate-shaped section in its widthwise direction, said plate-shaped section constructing said detecting section attached between said support base and said frame for surrounding said vibrator and said support base.
64. The method according to , wherein said resonance frequency for detection is adjusted after said resonance frequency for driving is adjusted.
claim 60
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/812,087 US6321599B2 (en) | 1996-03-29 | 2001-03-19 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8-076,434 | 1996-03-29 | ||
JP8-076434 | 1996-03-29 | ||
JP7643496 | 1996-03-29 | ||
JP20359596 | 1996-08-01 | ||
JP8-203595 | 1996-08-01 | ||
US08/952,596 US6065339A (en) | 1996-03-29 | 1997-03-28 | Vibration gyro sensor, combined sensor and method for producing vibration gyro sensor |
US09/545,688 US6244110B1 (en) | 1996-03-29 | 2000-04-07 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
US09/812,087 US6321599B2 (en) | 1996-03-29 | 2001-03-19 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
Related Parent Applications (1)
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US09/545,688 Division US6244110B1 (en) | 1996-03-29 | 2000-04-07 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
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US20010011479A1 true US20010011479A1 (en) | 2001-08-09 |
US6321599B2 US6321599B2 (en) | 2001-11-27 |
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Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/952,596 Expired - Fee Related US6065339A (en) | 1996-03-29 | 1997-03-28 | Vibration gyro sensor, combined sensor and method for producing vibration gyro sensor |
US09/545,688 Expired - Fee Related US6244110B1 (en) | 1996-03-29 | 2000-04-07 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
US09/812,087 Expired - Fee Related US6321599B2 (en) | 1996-03-29 | 2001-03-19 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
Family Applications Before (2)
Application Number | Title | Priority Date | Filing Date |
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US08/952,596 Expired - Fee Related US6065339A (en) | 1996-03-29 | 1997-03-28 | Vibration gyro sensor, combined sensor and method for producing vibration gyro sensor |
US09/545,688 Expired - Fee Related US6244110B1 (en) | 1996-03-29 | 2000-04-07 | Vibration gyro sensor, combined sensor, and method for producing vibration gyro sensor |
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US (3) | US6065339A (en) |
EP (2) | EP0939296A3 (en) |
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Also Published As
Publication number | Publication date |
---|---|
EP0829703A1 (en) | 1998-03-18 |
EP0939296A3 (en) | 2001-01-17 |
US6244110B1 (en) | 2001-06-12 |
EP0829703A4 (en) | 2000-04-19 |
US6065339A (en) | 2000-05-23 |
US6321599B2 (en) | 2001-11-27 |
EP0939296A2 (en) | 1999-09-01 |
WO1997037195A1 (en) | 1997-10-09 |
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