JP3701785B2 - Vibrator, vibratory gyroscope, linear accelerometer and measuring method of rotational angular velocity - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibrator, a vibratory gyroscope, a rotational angular velocity measuring method, and a linear accelerometer used in an angular velocity sensor used to detect a rotational angular velocity in a rotating system.
[0002]
[Prior art]
Conventionally, as an angular velocity sensor for detecting a rotational angular velocity in a rotating system, a vibratory gyroscope using a piezoelectric body has been used for confirming the position of an aircraft, a ship, a space satellite, or the like. Recently, it is used as a consumer field for car navigation, detection of camera shake of a VTR or a still camera, and the like.
[0003]
Such a piezoelectric vibrating gyroscope utilizes the fact that when an angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration. The principle is analyzed by a mechanical model (for example, “Acoustic wave device technology handbook”, Ohm, pages 491 to 497). Various piezoelectric vibratory gyroscopes have been proposed so far. For example, Sperry tuning fork type gyroscope, Watson tuning fork type gyroscope, equilateral triangular prism type piece gyroscope, cylindrical type piece gyroscope, etc. are known.
[0004]
[Problems to be solved by the invention]
However, in all of the conventional piezoelectric vibration type gyroscopes, the drive vibration of the drive vibration arm has some sort of influence on the detection arm as distortion, and noise is generated in the detection signal. For this reason, it has been difficult to improve the signal / noise ratio (S / N ratio) in the detection signal to some extent.
[0005]
An object of the present invention is to suppress the influence on the detection arm due to the drive vibration of the drive vibration arm in the piezoelectric vibration type gyroscope, and to improve the S / N ratio in the detection signal.
[0006]
[Means for Solving the Problems]
The present invention is a vibrator for rotating around a predetermined rotation axis, and the vibrator includes a frame portion in which a hollow region is formed inside, and a plurality of vibration systems, At least one of the plurality of vibration systems protrudes into the hollow region from an inner edge of the frame portion facing the hollow region. The plurality of vibration systems are formed so as to extend in a predetermined plane intersecting the rotation axis, and at least a pair of vibration systems of the plurality of vibration systems are mutually with respect to the center of gravity of the entire vibrator. Provided on the opposite side It is characterized by.
[0007]
The present invention also relates to a vibratory gyroscope for detecting a rotational angular velocity of a rotating system, wherein the vibrator, excitation means for exciting drive vibration to the vibrator, and vibration caused by rotation of the vibrator. And detecting means for detecting detection vibration generated in the child.
[0008]
The present invention also relates to a method for detecting the rotational angular velocity of a rotating system, which is caused by Coriolis force generated when drive vibration is excited in the vibrator and the vibrator is rotated in accordance with the drive vibration. The detection vibration excited by the vibrator is detected, and the rotational angular velocity is measured from the detection result.
[0009]
The present invention is also a linear accelerometer for detecting linear acceleration, wherein the transducer and the deformation of the transducer by Newton's force applied to the transducer when linear acceleration is applied to the transducer. The present invention relates to a linear accelerometer characterized by comprising a detecting means for detecting.
[0010]
The present inventor has conducted basic research on the vibration principle of a vibrator that can be used in a vibratory gyroscope. In this process, the inventors have succeeded in developing a vibrator and a vibratory gyroscope based on a completely new principle. This point will be described with reference to the schematic diagrams of FIGS.
[0011]
For example, in FIG. 1, the vibrator includes a frame portion 10A, and a plurality of predetermined vibration systems 1A, 1B, 2A, and 2B are provided in the hollow region 8 inside the frame portion 10A. Each vibration system protrudes from the inner edge 10a of the frame portion 10A toward the hollow region 8. The vibration systems 1A, 1B, 2A, and 2B are all connected via the frame portion 10A.
[0012]
In particular, in each embodiment shown in FIGS. 1-3, each vibration system and the frame portion extend in a predetermined plane, thereby forming a flat plate-like vibrator. In these embodiments, the rotational angular velocity can be detected by rotating the vibrator about the rotation axis Z as indicated by an arrow ω. The principle of detection of the rotational angular velocity in these embodiments will be further described, and then the advantages of the present invention will be described.
[0013]
Of the plurality of vibration systems, the first vibration system 1A, 1B Vibration of the center of gravity Includes radial vibration components 5A and 5B that vibrate in the radial direction within a predetermined plane when the center of gravity GO of the entire vibrator is the center. The first vibration . Also, the second vibration system 2A, 2B Vibration of the center of gravity Includes circumferential vibration components 6A and 6B that vibrate in the circumferential direction within a predetermined plane with the center of gravity GO of the entire vibrator as the center. Second vibration .
[0014]
When the vibration bodies 3A and 3B in the first vibration systems 1A and 1B are used as driving vibration bodies and the radial vibration components 5A and 5B are used as driving vibrations, the vibration systems 1A and 1B are rotated after rotation. In contrast, the Coriolis force 7A acts. Correspondingly, circumferential vibration components 6A and 6B are generated in the vibrating bodies 4A and 4B in the second vibration systems 2A and 2B. The vibrations of the vibration systems 2A and 2B mainly composed of the vibration component are detected, and the rotational angular velocity is calculated from the detected value.
[0015]
Further, when the vibrating bodies 4A and 4B in the second vibration systems 2A and 2B are used as driving vibration bodies and the circumferential vibration components 6A and 6B are used as driving vibrations, the vibration systems 2A, Coriolis force 7B acts on 2B. Corresponding to this, radial vibration components 5A and 5B are generated in the vibrating bodies 3A and 3B in the first vibration systems 1A and 1B. This vibration component is detected, and the rotational angular velocity is calculated from the detected value.
[0016]
According to the vibratory gyroscope of this form, since the drive vibration system is on both sides of the center of gravity GO of the entire vibrator, the drive vibration is buffered and offset, and the influence of the drive vibration is transmitted to the detection vibration system. It is hard to be done. At this time, it is important that the drive vibration system and the detection vibration system protrude from the frame portion 10A, whereby each vibration of each vibration system that vibrates differently is effectively separated. It was found that the S / N ratio was improved. In this respect, the present invention solves the fundamental problem inherent in the vibration type gyroscope.
[0017]
Note that the circumferential vibration component refers to a vibration component that vibrates in the circumferential direction within a predetermined plane as viewed from the center of gravity GO of the entire vibrator. The radial vibration component refers to a vibration component that vibrates in the diameter direction of a circle within a predetermined plane when viewed from the center of gravity GO of the entire vibrator, that is, a direction away from the center of gravity GO of the entire vibrator. A component that vibrates alternately with respect to the approaching direction.
[0018]
According to such a vibrator and a vibratory gyroscope, the vibrator drive vibration and the vibration for detection are both performed within a predetermined plane, and the vibrator arm of the vibrator intersects the rotation axis. Even when the vibrator is installed so as to extend in the direction, it is possible to detect the rotational angular velocity with sufficiently high sensitivity without providing a protrusion having a constant weight in the direction of the rotation axis from the vibrator.
[0019]
As shown in FIGS. 1 to 3, for example, when the radial vibration components 5A and 5B in the first vibration systems 1A and 1B are used as drive vibrations, the first vibration system reduces the center of gravity GO of the entire vibrator. As a result, the drive vibrations cancel each other. As a result, the influence of the drive vibration on the second vibration system for detecting the detected vibration is reduced.
[0020]
In this way, a plurality of first vibration systems can be provided, and each vibration system can be provided in a rotationally symmetric position around the center of gravity GO of the entire vibrator. For example, in FIGS. 1 to 3, the first vibration systems 1 </ b> A and 1 </ b> B are provided at positions that are two-fold symmetrical about the center of gravity GO.
[0021]
It is preferable that a plurality of second vibration systems are provided, and each second vibration system is provided at a rotationally symmetric position with respect to the center of gravity GO. For example, in FIGS. 1 to 3, the second vibration systems 2 </ b> A and 2 </ b> B are provided at positions that are two-fold symmetrical about the center of gravity GO.
[0022]
Here, each vibration system being in a rotationally symmetric position with the center of gravity GO as the center means a state where a plurality of vibration systems in question are separated from each other by the same predetermined angle within a predetermined plane with the center of gravity GO as the center. . Therefore, when an operation is performed to rotate one vibration system by a predetermined angle within a predetermined plane, the vibration system is positioned at another vibration system. For example, in FIGS. 1 to 3, the first vibration systems 1 </ b> A and 1 </ b> B are separated from each other by 180 °, and therefore, when an operation of rotating the vibration system 1 </ b> A by 180 ° is performed, the first vibration system 1 </ b> A is positioned.
[0023]
Specifically, the rotational symmetry is preferably a 2-fold symmetry, 3-fold symmetry, or 4-fold symmetry. Further, whether the drive vibration system is the first vibration system or the second vibration system, a plurality of drive vibration systems are provided at rotationally symmetric positions with the center of gravity GO as the center. Since the influence on the minute detection vibration can be suppressed, the effect is great.
[0024]
In particular, it is preferable that the entire center of gravity GD of the vibration of the drive vibration system (for example, the first vibration system 1A, 1B) is located in a region near the center of gravity GO. The influence on the vibration system) can be suppressed.
[0025]
Specifically, the fact that the entire center of gravity GD of the vibration of the drive vibration system is located in the region near the center of gravity GO may be substantially located on the center of gravity GO, but the diameter from the center of gravity GO is 1 mm. Means it is in the circle.
[0026]
In FIG. 1 (and FIGS. 2 to 6), the rotation center (intersection of the rotation axis and the predetermined surface) O coincides with the center of gravity GO of the vibrator and the entire center of gravity GD of the drive vibration. However, O need not match GO. This is because the vibrator of the present invention is basically useful even when the rotation center O does not coincide with the center of gravity GO of the vibrator, and even when the rotation center O is located outside the vibrator. This is because it can be used for the vibratory gyroscope of the present invention.
[0027]
This is because when the vibrator is rotating, the displacement speed of each part of the vibrator when the center of rotation O and the center of gravity GO of the vibrator do not coincide is the same as the center of gravity GO of the vibrator. In this case, the vector sum of the displacement speed of each part of the vibrator (displacement of each part of the vibrator due to rotation) and the displacement speed caused by the translational motion of each part of the vibrator in the case of being applied. This is because the Coriolis force does not act on the displacement speed due to the translational motion of each part of the vibrator, and can be eliminated without being detected by the vibratory gyroscope.
[0028]
“A plurality of vibration systems extending in a predetermined plane” includes a case where a plurality of vibration systems are formed within a thickness of 1 mm or less. Further, the part other than the vibration system may protrude from the predetermined surface, but it is preferable that the entire vibrator is formed within the predetermined surface.
[0029]
The angle formed between the predetermined surface and the rotation axis is preferably 60 to 120 degrees, more preferably 85 to 95 degrees, and still more preferably orthogonal.
[0030]
In the present invention, as illustrated in FIG. 1, all of the first vibration system and the second vibration system can be protruded from the inner edge of the frame portion. In this case, the vibration of the drive vibration system can be suppressed from affecting the detection vibration system, and the width of the vibrator can be minimized, so that a compact vibrator can be provided. In particular, when a vibrator is produced by processing a piezoelectric single crystal, a piezoelectric single crystal flat plate is prepared, the peripheral portion of the flat plate is used as a frame portion, and the inside of the frame portion is processed. The vibrator can be manufactured only by this.
[0031]
In FIG. 2, the first vibration systems 1A and 1B are projected from the inner edge 10a of the frame portion 10B to the hollow region 8, and the second vibration systems 2A and 2B are outward from the outer edge 10b of the frame portion 10B. It protrudes toward Also in this case, each vibration system operates as described above. In contrast to the one shown in FIG. 2, the second vibration systems 2A and 2B are projected from the inner edge 10a of the frame portion 10B to the hollow region 8, and the first vibration systems 1A and 1B are moved to the frame portion 10B. It can project toward the outside from the outer edge 10b.
[0032]
In this way, driving is performed by providing one of the driving vibration system (for example, the first vibration system) and the detection vibration system (for example, the second vibration system) inside the frame portion and the other outside the frame portion. The influence on the detection signal due to vibration of the vibration system is further reduced.
[0033]
In FIG. 3, the base 9 is provided in the hollow area 8 inside the frame 10C. The second vibration systems 2A and 2B protrude from the inner edge 10a of the frame portion 10C toward the base portion 9. The first vibration systems 1A and 1B extend radially from the peripheral edge 9a of the base 9 in a direction away from the center of gravity GO.
[0034]
In FIG. 3, the first vibration systems 1A and 1B are protruded from the inner edge 10a of the frame portion 10C toward the base 9, and the second vibration systems 2A and 2B are moved from the peripheral edge 9a of the base 9. It can be formed to extend radially in a direction away from the center of gravity GO. Further, in FIG. 3, the second vibration systems 2A and 2B can be projected from the outer edge 10b of the frame portion 10C toward the outside of the frame portion 10C.
[0035]
In this way, by providing one of the drive vibration system (for example, the first vibration system) and the detection vibration system (for example, the second vibration system) at the base and the other at the frame portion, The influence on the detection signal is further reduced.
[0036]
The first vibration system includes, for example, a support portion protruding in a radial direction from the peripheral edge portion of the base portion, the inner edge of the frame portion or the outer edge of the frame portion, and a first bending vibration piece extending in a direction intersecting the support portion. And. In the first vibration system, the longitudinal direction of the support portion and the longitudinal direction of the first bending vibration piece are not necessarily perpendicular, but are preferably perpendicular. In the simplest form, the second vibration system includes a second flexural vibration piece projecting radially from the peripheral edge of the base, the inner edge of the frame, or the outer edge of the frame. By providing a weight portion on the second bending vibration piece, the overall dimension of the bending vibration piece can be shortened.
[0037]
Hereinafter, more specific embodiments of the present invention will be described.
When the displacement of the vibrator of the present invention occurs in a predetermined plane, the whole vibrator can be formed of the same piezoelectric single crystal. In this case, first, a piezoelectric single crystal thin plate is prepared, and the thin plate is processed by etching and grinding, whereby a vibrator can be manufactured. Each part of the vibrator can be formed by a separate member, but it is particularly preferable that the parts are integrally formed.
[0038]
When a vibrator is formed from a flat plate material, for example, a piezoelectric single crystal flat plate material such as quartz, by an etching process, a protrusion having a specific shape on each constituent piece such as each bending vibration piece of the vibrator, for example, An elongated protrusion may be generated. Strictly speaking, such protrusions cause a decrease in the symmetry of the vibrator planned at the time of design. However, this protrusion may be present, and it is preferable that the height of the protrusion is small. However, if the height of the protrusion is 1/5 or less of the width of the constituent piece of the vibrator, it can be generally used without any problem. The same applies to the case where an asymmetric part other than the protrusion due to other manufacturing causes exists in the vibrator.
[0039]
In addition, when protrusions and the like are present on the vibrator as described above, by removing a part of the protrusions by laser processing or the like, or by removing parts other than the protrusions of the vibrator by laser processing or the like, The center of gravity GD of the driving vibration system can be adjusted after the etching process so that the center of gravity GD of the driving vibration system is located in a region near the center of gravity GO of the vibrator during driving.
[0040]
Further, the material of the vibrator is not particularly limited, but crystal, LiNbO _Three LiTaO _Three Lithium niobate-lithium tantalate solid solution (Li (Nb, Ta) O _Three It is preferable to use a piezoelectric single crystal made of a single crystal, a lithium borate single crystal, a langasite single crystal, or the like.
[0041]
Among the single crystals described above, LiNbO _Three Single crystal, LiTaO _Three The single crystal, lithium niobate-lithium tantalate solid solution single crystal has a particularly large electromechanical coupling coefficient. LiNbO _Three Single crystal and LiTaO _Three Compared with single crystal, LiTaO _Three Single crystal is LiNbO _Three The electromechanical coupling coefficient is larger than that of the single crystal, and the temperature stability is better.
[0042]
When a piezoelectric single crystal is used, detection sensitivity can be improved and detection noise can be reduced. In addition, when a piezoelectric single crystal is used, a vibrator that is particularly insensitive to temperature changes can be manufactured, and such a vibrator is suitable for in-vehicle use that requires temperature stability. This point will be further described.
[0043]
As an angular velocity sensor using a tuning fork type vibrator, for example, there is a piezoelectric vibration type gyroscope described in JP-A-8-128833. However, in such a vibrator, the vibrator vibrates in two directions. For this reason, when the vibrator is formed of a piezoelectric single crystal, it is necessary to match the characteristics of the two directions of the piezoelectric single crystal. However, in reality, the piezoelectric single crystal has anisotropy.
[0044]
In general, a piezoelectric vibration type gyroscope is required to maintain a certain vibration frequency difference between the natural resonance frequency of the driving vibration mode and the natural resonance frequency of the detection vibration mode in order to improve measurement sensitivity. ing. However, the piezoelectric single crystal has anisotropy, and when the crystal plane changes, the degree of temperature change of the vibration frequency differs. For example, when cutting along a specific crystal plane, there is almost no change in temperature of the vibration frequency, but when cutting along another crystal plane, the vibration frequency responds sensitively to temperature change. Therefore, when the vibrator vibrates in two directions, at least one of the two vibration surfaces becomes a crystal surface with a large temperature change of vibration frequency.
[0045]
In contrast, by making the entire vibrator vibrate within a predetermined plane and forming the vibrator by a piezoelectric single crystal, only the crystal plane having the best temperature characteristics of the single crystal can be used in the vibrator. Became.
[0046]
In other words, since the entire vibrator is designed to vibrate within a predetermined plane, it is possible to manufacture the vibrator using only the crystal plane of the piezoelectric single crystal that hardly changes the temperature of the vibration frequency. it can. As a result, a vibratory gyroscope with extremely high temperature stability can be provided.
[0047]
When the vibrator of the present invention is formed of a piezoelectric material, the vibrator is provided with a drive electrode and a detection electrode. Examples of the piezoelectric material include piezoelectric ceramics such as PZT in addition to the piezoelectric single crystal.
Further, the vibrator of the present invention can be formed of a constant elastic metal such as Elinvar. In this case, it is necessary to attach a piezoelectric body to a predetermined portion of the vibrator.
[0048]
In addition to the piezoelectric material and the constant elastic alloy described above, the vibrator of the present invention can also be formed by a silicon semiconductor process so as to be used in a silicon micromachine. In this case, electrostatic force or the like is used when driving the vibrator.
[0049]
The vibratory gyroscope of the present invention can be used, for example, in a rotational speed sensor used in a vehicle control method of a vehicle body rotational speed feedback type of an automobile. In such a system, the direction of the steering wheel itself is detected by the rotation angle of the steering wheel. At the same time, the rotational speed at which the vehicle body is actually rotating is detected by the vibration gyroscope. Then, the direction of the steering wheel is compared with the actual rotational speed of the vehicle body to obtain a difference, and based on this difference, correction is made to the wheel torque and the steering angle, thereby realizing stable vehicle body control.
[0050]
The vibrating gyroscope having the configuration shown in FIGS. 1 to 3 can detect the rotational angular velocity even when the vibrator is arranged perpendicularly to the rotation axis (so-called horizontal placement).
[0051]
4 to 6 are perspective views schematically showing the vibrator of each vibration gyroscope according to each embodiment of the present invention.
[0052]
The vibrator shown in FIG. 4 corresponds to the type shown in FIG. However, in the present embodiment, two frame portions 10D are provided by dividing the frame portion in FIG. The base portion 9A has a four-fold symmetric square with respect to GO. Two drive vibration systems 1A and 1B (first vibration system in this example) protrude from the peripheral portion 9a of the base 9A. The drive vibration systems 1A and 1B are two-fold symmetric about GO.
[0053]
The drive vibration systems 1A and 1B include a support portion 12 that protrudes from the peripheral edge portion 9a of the base portion 9A, and first bending vibration pieces 3C and 3D that extend in a direction orthogonal to the support portion 12 from the distal end 12b side of the support portion 12. ing. As for each bending vibration piece 3C, 3D, the center part is restrained and both ends are open | released. More specifically, the first bending vibration piece includes bending vibration pieces 11A, 11B, and 11C, 11D.
[0054]
In each of the detection vibration systems 2A and 2B, the frame portion 10D protrudes from the base portion 9, and the elongated circumferential bending vibration pieces 4C and 4D protrude from the hollow region 8A of each frame portion 10D, respectively. Each of the bending vibration pieces 4C and 4D extends in the radial direction when viewed from the center of gravity GO, and the end 13 on the side farthest from the center of gravity GO of each bending vibration piece is fixed to the frame portion 10D. The detection vibration systems 2A and 2B are two-fold symmetric about the center of gravity GO.
[0055]
At the time of driving, the bending vibration pieces 3C and 3D are bent and vibrated as indicated by arrows 5A and 5B with the vicinity of the front end portion 12b of the support portion 12 as a center. When this vibrator is rotated, a Coriolis force acts on each support portion 12 as shown by an arrow 7A, and each support portion 12 bends and vibrates in the circumferential direction around the fixing portion 12a to the base portion. In response to this, the bending vibration pieces 4C and 4D of the detection vibration system bend and vibrate as indicated by arrows 6A and 6B. At this time, the vibrations of the bending vibration pieces 4C and 4D increase as the distance from the center of gravity GO increases, and decrease as the distance from the center of gravity GO increases.
[0056]
The vibrator of FIG. 5 corresponds to the type of FIG. Two drive vibration systems 1A and 1B protrude from the inner edge 10a of the frame portion 10C in the hollow region 8B inside the frame portion 10C.
[0057]
The drive vibration systems 1A and 1B include a support portion 12A protruding from the inner edge 10a of the frame portion 10C, and first bending vibration pieces 3E and 3F extending in a direction orthogonal to the support portion 12A from the tip 12b side of the support portion 12A. ing. As for each bending vibration piece 3E, 3F, the center part is restrained and both ends are open | released. More specifically, the first bending vibration piece includes bending vibration pieces 11E and 11F, and 11G and 11H. The drive vibration systems 1A and 1B are two-fold symmetric about the center of gravity GO.
[0058]
In each of the detection vibration systems 2A and 2B, the bending vibration pieces 4E and 4F protrude from the outer edge 10b of the frame portion 10C. Each bending vibration piece 4E, 4F extends in the radial direction as viewed from the intersection point O, and an end portion 13A closest to the center of gravity GO of each bending vibration piece is fixed to the frame portion 10C. The detection vibration systems 2A and 2B are two-fold symmetric about the center of gravity GO.
[0059]
At the time of driving, each bending vibration piece 3E, 3F bends and vibrates as indicated by arrows 5A, 5B around the vicinity of the tip portion 12b of the support portion 12A. When this vibrator is rotated, a Coriolis force acts on each support portion 12A as shown by an arrow 7A, and each support portion 12A bends and vibrates around the fixing portion 12a to the frame portion. The magnitude of this vibration increases as it is closer to the center of gravity GO, and decreases as it is farther from the center of gravity GO. Correspondingly, the bending vibration pieces 4E and 4F of the detection vibration system bend and vibrate as indicated by arrows 6A and 6B.
[0060]
The vibrator shown in FIG. 6 corresponds to the type shown in FIG. Two drive vibration systems 1A and 1B protrude from the inner edge 10a of the frame portion 10C in the hollow region inside the frame portion 10C. Each drive vibration system is the same as that shown in FIG.
[0061]
In each of the detection vibration systems 2A and 2B, the bending vibration pieces 4C and 4D protrude from the inner edge 10a of the frame portion 10C. Each of the bending vibration pieces 4C and 4D extends in the radial direction as viewed from the intersection point O, and the end 13 on the side farthest from the center of gravity GO of each bending vibration piece is fixed to the frame portion 10C.
[0062]
At the time of driving, the bending vibration pieces 3E and 3F bend and vibrate as indicated by arrows 5A and 5B. When this vibrator is rotated, a Coriolis force acts on each support portion 12A as shown by an arrow 7A, and each support portion 12A bends and vibrates around the fixing portion 12a to the frame portion. The magnitude of this vibration increases as it is closer to the center of gravity GO, and decreases as it is farther from the center of gravity GO. Correspondingly, the bending vibration pieces 4C and 4D of the detection vibration system bend and vibrate as indicated by arrows 6A and 6B. At this time, the vibrations of the bending vibration pieces 4C and 4D increase as the distance from the center of gravity GO increases, and decrease as the distance from the center of gravity GO increases.
[0063]
In the vibratory gyroscope of the present invention, it is particularly preferable that the inside of the frame is supported and fixed. Thereby, the detection vibration generated by the Coriolis force can be effectively generated without being attenuated, the Q value of the detection vibration is increased, and the sensitivity can be increased. In this case, it is particularly preferable that the vibrator is held in a region that is substantially equidistant with respect to each drive vibration system. Here, the “region that is substantially equidistant with respect to each drive vibration system” refers to a region in which the difference in distance from each point in the region to each drive vibration system is within 1%.
[0064]
For example, in FIGS. 4, 5, and 6, when the vibrator is held in the region 20 in the frame portion, the influence of the drive vibration and the detection vibration is minimized, and the sensitivity is improved.
[0065]
The specific method for supporting the vibrator is not particularly limited, and any support method and fixing method can be adopted.
[0066]
For example, any known bonding method can be used as a bonding method of the piezoelectric material. As an example, the vibrator can be fixed by providing a predetermined support hole in the vibrator and inserting some support into the support hole. For example, the support tool can be protruded from a jig for supporting the vibrator, and the support tool can be inserted into the support hole and fixed. When inserting and fixing the support tool into the support hole, a metallized layer is provided on the surface of the support tool and / or a metallized layer is provided on the inner peripheral surface of the support hole, and then the inner periphery of the support tool and the support hole. Solder or braze the surface. Alternatively, the vibrator can be fixed by arranging a resin between the support and the support hole.
[0067]
The support hole may penetrate the vibrator or may not penetrate the vibrator. When the support hole is a through hole penetrating the vibrator, the support tool can be passed through the support hole, but the support tool need not be passed through.
[0068]
Further, when the vibrator is not provided with a support hole, the support tool can be soldered to the front surface and / or the back surface of the vibrator, or the support tool can be bonded with resin.
[0069]
According to the linear accelerometer using the vibrator of the present invention, the noise signal due to the stretching vibration of the base when driving vibration is applied to the vibrator is remarkably reduced. Can be prevented.
[0070]
In addition, a sensor that simultaneously measures the rotational speed and the linear acceleration can be manufactured using the vibrator of the present invention. In the vibrator of the present invention, when a rotational speed and a linear acceleration are simultaneously applied to the vibrator, a detection signal corresponding to the rotational speed and a signal corresponding to the linear acceleration are generated simultaneously. Among the detection signals at this time, the change in the amplitude of the signal component having the same frequency as that of the drive signal is proportional to the rotation speed, and the change in the DC voltage signal component is proportional to the linear acceleration.
[0071]
A vibrator having the form shown in FIG. 6 was produced, and the S / N ratio was measured. However, 200 angstroms of chromium and 3000 angstroms of gold are vapor-deposited on both sides of a 0.3 mm thick quartz crystal Z plate, and a mask pattern is formed by photolithography so that the arm length becomes 6 mm. A vibrator having the shape shown in FIG. 6 was produced by an etching method using an ammonium fluoride solution. Furthermore, 200 angstroms of chromium and 3000 angstroms of gold were vapor-deposited as electrodes in the predetermined pattern on the surface of the vibrator to produce a vibrator. When the S / N ratio of the gyroscope using this vibrator was measured, it was 1500.
[0072]
When measuring the S / N ratio, the amplitude of the voltage appearing on the detection electrode when the vibrator is not installed in the rotating system is defined as noise (N). Further, when the vibrator is installed in a rotating system with a rotational angular velocity of 1 radians / second, the amplitude of the voltage appearing on the detection electrode is defined as a signal (S). And said signal (S) / noise (N) was made into S / N ratio.
[0073]
【The invention's effect】
As described above, according to the present invention, in the piezoelectric vibration type gyroscope, the influence on the detection arm due to the drive vibration of the drive vibration arm can be suppressed, and the S / N ratio in the detection signal can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a vibrator of an embodiment in which each vibration system is provided in a hollow region inside a frame portion 10A.
FIG. 2 is a schematic diagram showing a vibrator in which a first vibration system is provided in a hollow region inside the frame portion 10B, and a second vibration system protrudes toward the outside of the frame portion 10B. is there.
FIG. 3 is a schematic diagram showing a vibrator in which a second vibration system is provided in a hollow region inside the frame portion 10C, and the first vibration system protrudes from a base portion in the frame portion 10C.
FIG. 4 is a perspective view schematically showing a vibrator according to an embodiment of the invention.
FIG. 5 is a perspective view schematically showing a vibrator according to another embodiment of the present invention.
FIG. 6 is a perspective view schematically showing a vibrator according to still another embodiment of the present invention.
[Explanation of symbols]
1A, 1B First vibration system 2A, 2B Second vibration system 3C, 3D First bending vibration piece 4C, 4D Circumferential bending vibration piece 8, 8A, 8B Hollow region 9, 9A Base 10A, 10B, 10C, 10D frame portion 10a inner edge of frame portion 10b outer edge of frame portion 12, 12A support portion O intersection of predetermined surface and rotation axis Z

Claims (10)

A vibrator for rotating around a predetermined rotation axis, the vibrator comprising a frame portion having a hollow region formed therein and a plurality of vibration systems, the plurality of vibration systems At least one of the frame portion protrudes from the inner edge of the frame portion facing the hollow region into the hollow region, and the plurality of vibration systems are formed to extend in a predetermined plane intersecting the rotation axis. The vibrator is characterized in that at least a pair of vibration systems among the plurality of vibration systems are provided at positions opposite to each other with respect to the center of gravity of the whole vibrator. 2. The vibrator according to claim 1, wherein all of the plurality of vibration systems protrude from the inner edge of the frame portion into the hollow region. The plurality of vibration systems are divided into a drive vibration system and a detection vibration system, and one of the drive vibration system and the detection vibration system is separated from the inner edge of the frame portion. protrudes into the hollow region, the other of the vibration system for the detection and vibration system for the drive, characterized in that provided on the outer edge side of the frame portion, according to claim 1 or 2, wherein Vibrator. The plurality of vibration systems are divided into a drive vibration system and a detection vibration system, and a base portion separated from the frame portion is provided in the hollow region, and the drive vibration system One of the vibration system for detection and the vibration system for detection is provided on the inner edge of the frame portion or the outer edge side of the frame portion, and the other of the vibration system for driving and the vibration system for detection is the characterized in that provided on the base, according to claim 1 or 2 vibrator according. Vibration of the center of gravity of the plurality of vibration systems, the centered on the center of gravity of the entire vibrator was first vibration including the specified plane radial vibration component oscillating in the radial direction when the, the entire vibrator wherein the second vibration and including things including a circumferential vibration component that vibrates in the circumferential direction at a predetermined plane when the center of gravity, to any one of claims 1-4 The vibrator described. A vibratory gyroscope for detecting a rotational angular velocity of a rotary system, wherein the vibrator according to any one of claims 1 to 5 and excitation means for exciting drive vibration to the vibrator And a vibrating gyroscope comprising: detecting means for detecting detected vibration generated in the vibrator by the rotation of the vibrator. The vibrating gyroscope according to claim 6 , further comprising a support member that supports the vibrator with the frame portion. A vibratory gyroscope for detecting a rotational angular velocity of a rotary system, comprising: the vibrator according to claim 3 ; excitation means for exciting drive vibration to the vibrator; and the vibration by rotation of the vibrator. Detecting means for detecting the detected vibration generated in the child, and one of the first vibration system and the second vibration system is used as a drive vibration system, and the other is used as a detection vibration system. This is a vibrating gyroscope. A method for detecting a rotational angular velocity of a rotating system, wherein a drive vibration is excited in the vibrator according to any one of claims 1 to 5 , and the vibrator is rotated in accordance with the drive vibration. A method of detecting a rotational angular velocity of a rotating system, wherein a detection vibration excited by the vibrator due to a Coriolis force generated at the time is detected, and the rotational angular velocity is measured from the detection result. A linear accelerometer for detecting linear acceleration, wherein the vibrator according to any one of claims 1 to 5 and a Newton applied to the vibrator when linear acceleration is applied to the vibrator. A linear accelerometer, comprising: detecting means for detecting the deformation of the vibrator due to the force of.

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