JP4666578B2 - Ultrasonic vibration element and ultrasonic actuator using the same - Google Patents

Description

  The present invention relates to an ultrasonic vibration element that uses vibration excited by displacement of a piezoelectric material as a drive source, and an ultrasonic actuator for an ultrasonic motor using the ultrasonic vibration element.

  Ultrasonic motors are small and excellent in quietness, can generate high torque, have large holding power, and do not generate electromagnetic noise. Recently, they have attracted attention as a new motor that can replace electromagnetic motors. It has begun to be used as a power source for various devices. 1 and 2 show an example of an actuator-type ultrasonic motor, FIG. 1 is a perspective view showing a Y-type ultrasonic linear actuator, and FIG. 2 is a side view showing a π-type ultrasonic linear actuator. is there. Linear means a motor that performs a linear operation.

  The Y-type ultrasonic linear actuator 10 includes a vibration element 11 as a driving source and an elastic body 12 for converting the expansion / contraction motion (vibration) generated by the vibration element 11 into an ultrasonic elliptical motion and transmitting it to the driven body 13. And have a joined structure. Similarly, the π-type ultrasonic linear actuator 20 includes the vibration element 11 as a driving source and an elastic body 22 for converting the expansion and contraction motion generated by the vibration element 11 into an ultrasonic elliptical motion and transmitting the ultrasonic motion to the driven body 23. And have a joined structure. In order to drive the Y-type ultrasonic linear actuator 10 and the π-type ultrasonic linear actuator 20 efficiently, it is desirable to drive them in the vicinity of the resonance frequency. It is desirable to make one end free (refer to Non-Patent Document 1 for the ultrasonic motor).

JP-A-9-85172 JP 2003-180091 A JP 2001-68749 A New Actuator Handbook for Precision Control (Japan Industrial Technology Promotion Association Solid Actuator Research Group), 942-958 pages, Part II Application, Chapter 2 Ultrasonic Motor, Section 9 Ultrasonic Linear Motor FC Report 20 (2002) No. 11 pages 248-250 Nolia Application Note, Comparing d31 versus d33 Actuators

  FIG. 3A and FIG. 3B are cross-sectional views illustrating a d33 (piezoelectric longitudinal effect) driven multilayer piezoelectric element that is conventionally used as the vibration element 11. The laminated piezoelectric element 30 shown in FIG. 3 (a) and the laminated piezoelectric element 31 shown in FIG. 3 (b) are both laminated with a piezoelectric layer 14 sandwiched between electrode layers 18 and 19. It is polarized in the direction. When a voltage is applied in the same direction as the polarization direction, it is displaced in the same direction as the stacking direction, that is, the direction in which the stacked piezoelectric element extends, based on the piezoelectric longitudinal effect. In order to obtain a larger expansion / contraction displacement, it is necessary to increase the number of stacked piezoelectric layers 14.

  In the laminated piezoelectric elements 30 and 31, it is necessary to change the polarity of the electrode layers 18 and 19 every other layer. Therefore, a non-displacement part or a part that restrains the displacement is likely to be generated. There is a problem to be improved that the amount is reduced.

  In the laminated piezoelectric element 31, one end of the electrode layers 18 and 19 is alternately embedded in the piezoelectric layer 14 so that the polarity of the electrode layers 18 and 19 can be changed every other layer. In this way, the external electrodes 28 and 29 can be directly attached to the outer periphery, which facilitates manufacture, but the end portions of the piezoelectric layer 14 where the electrode layers 18 and 19 are not opposed become non-displaceable portions. Further, the external electrodes 28 and 29 directly attached to the outer periphery restrain the expansion / contraction displacement.

  In the laminated piezoelectric element 30, the electrode layers 18 and 19 are provided on the entire surface of the piezoelectric layer 14, and the polarities of the electrode layers 18 and 19 are changed every other layer by alternately covering the exposed portions on the outer periphery with the insulating portions 15. Trying to get. This eliminates the non-displaced portion and reduces the stress concentration, but in order to increase the insulation reliability, the insulation portion 15 must be made larger than a certain size, and this insulation portion 15 is directly attached to the outer periphery. Together with the external electrodes 28 and 29, the expansion and contraction displacement is constrained. In addition, the manufacturing process becomes complicated, and there is a limit to reducing the cost (see Non-Patent Document 2 for the same type as the multilayer piezoelectric element 30).

  Further, in the stacked piezoelectric elements 30 and 31, the amount of displacement is determined by the number of stacked layers of the piezoelectric layer 14. Therefore, in order to obtain a large amount of displacement, the number of stacked layers must be increased, resulting in an increase in cost. Furthermore, due to the structure in which the stacking direction of the piezoelectric layer 14 and the electrode layers 18 and 19 coincides with the expansion / contraction displacement direction, it has a problem that it is easily broken from the stacking surface when driving with a large amplitude near the resonance frequency. Yes.

  In addition, multilayer piezoelectric elements utilizing the piezoelectric longitudinal effect, such as the multilayer piezoelectric elements 30 and 31, were originally developed for precision positioning applications and are usually used with a compressive load (preload) applied. It is desirable to do. Therefore, due to its structure and characteristics, there are the following problems when it is used in a preferable mode as a vibration element for an ultrasonic motor.

  First, as described above, since the piezoelectric layers and the electrode layers are alternately laminated in the expansion / contraction direction, the tensile force is weak. However, the piezoelectric layer and the electrode layer are easily broken particularly in a usage mode in which one end is free to vibrate. In particular, even if it is applied as a vibration element used in the vicinity of the resonance frequency and an attempt is made to drive with a large amplitude vibration by applying a high drive voltage, the drive voltage cannot be increased because the element may be destroyed. In addition, there is a problem in durability even when a high drive voltage is not applied and the apparatus is vibrated for a long time at a frequency in the ultrasonic region.

  Next, there are many electrode layers perpendicular to the transmission direction (stretching direction) of vibration energy to the vibration element, and the external electrode restrains expansion / contraction displacement, so that energy loss due to vibration is large. In particular, the mechanical quality factor indicating the performance of the vibration element used in the vicinity of the resonance frequency rapidly decreases when the drive voltage is increased, and the vibration energy does not increase even when the drive voltage is increased.

  Since the multilayer piezoelectric element using the piezoelectric longitudinal effect has such a problem, it is necessary to consider other types of piezoelectric elements. For example, according to the description of Non-Patent Document 3, a multilayer piezoelectric actuator (element) that exhibits displacement based on the piezoelectric lateral effect (d31) is shown. However, in the disclosed multilayer piezoelectric actuator, the external electrode is provided at a position (both end faces in the displacement direction) that restrains displacement of the actuator side surface, and even if the piezoelectric lateral effect is used, Similar to the multilayer piezoelectric element that develops displacement based on the piezoelectric longitudinal effect, energy loss due to vibration is large. Further, when driving at a frequency in the ultrasonic region for a long time, the external electrode is partially fatigued and easily broken. Furthermore, the described actuator is used for a static positioning mechanism and is different from an ultrasonic vibration element.

  Hereinafter, prior patent documents will be described. For example, according to the description in Patent Document 1, a structure is described in which a vibration detecting piezoelectric element is bonded or integrally formed with a vibrating element made of a laminated piezoelectric element. However, both ends of the vibration element are held and one end is not free, and there is a limit to improving the efficiency of vibration generation as a vibration element that generates ultrasonic waves. In addition, since the multilayer piezoelectric element exhibits a displacement based on the piezoelectric longitudinal effect, it has the same problem as the multilayer piezoelectric elements 30 and 31.

  Further, according to the description of Patent Document 2, an ultrasonic linear motor is described in which a laminated piezoelectric element is used as a vibration element (piezoelectric element) as a driving source and one end vibrates freely. However, the detailed structure and driving principle of the piezoelectric element are not described.

  Furthermore, according to the description of Patent Document 3, a multilayer piezoelectric actuator (element) that expresses displacement based on the piezoelectric lateral effect (d31) is described. However, the described actuator has a serious problem as an ultrasonic vibration element. That is, in the disclosed actuator, in order to simplify the insulation process, no electrode is formed on the entire surface of the piezoelectric ceramic layer (piezoelectric body) before lamination, and an electrode non-formed portion remains on the outer peripheral portion ( FIG. 2 of Patent Document 3), and the outer peripheral surface portion of the laminated body formed by laminating the piezoelectric ceramic layers on which the electrodes are formed in such a manner has a structure that is not displaced. When a large amplitude vibration is generated in the vicinity of the resonance frequency for a multilayer piezoelectric actuator with such a structure, the piezoelectric ceramic layer that is not displaced restrains the vibration, resulting in a large energy loss or damage to the actuator itself. There is a high possibility that

  Next, a laminated piezoelectric element obtained in the course of the applicant's research and not suitable as an ultrasonic vibration element will be described with reference to FIGS. 8 (a), 8 (b), and 8 (c). To do. The laminated piezoelectric element 81 shown in FIG. 8A is substantially the same as the laminated piezoelectric element 31 shown in FIG. 3 in structure, but the electrode layers are formed on the uppermost surface and the lowermost surface, and the piezoelectric lateral effect is obtained. This is a piezoelectric element that excites vibration by displacement based on the above. The laminated piezoelectric element 81 is not constrained on the side surface (the surface where the electrode layers 48 and 49 are exposed in FIG. 8A), and the electrode layers 48 and 49 are present on the entire surface of the vibration generating portion 76. Excellent in terms. However, since the external electrodes 78 and 79 are provided on both end surfaces in the S direction that are subject to displacement (vibration), there is a possibility that displacement (vibration) may be impeded in practice. This is because the external electrodes 78 and 79 are often used while being fixed to either one.

  8B is provided with a non-operating portion 85 on a surface parallel to the S direction applied to displacement (vibration). In the vibration generating portion 76, the electrode layers 48 and 49 are provided. Since the piezoelectric layer 44 is not laminated on the entire surface, vibration is prevented.

  Further, the multilayer piezoelectric element 83 shown in FIG. 8C has substantially the same structure as the multilayer piezoelectric element 81, but the surface parallel to the S direction in which the external electrodes 78 and 79 are subjected to displacement (vibration). This prevents vibrations.

  The present invention has been made in view of the above-described circumstances or problems of the prior art, and the object of the present invention is even when driving at a large amplitude near the resonance frequency with one end free. Another object of the present invention is to provide an ultrasonic vibration element that is difficult to be destroyed, has durability, has low energy loss, is highly efficient, and can be manufactured at a lower cost, and an ultrasonic actuator using the ultrasonic vibration element. As a result of repeated studies on multilayer piezoelectric elements that exhibit displacement based on the piezoelectric lateral effect, it has been found that the above object can be achieved by the following means.

  [1] A drive that has a plurality of piezoelectric layers made of piezoelectric material and a plurality of electrode layers made of a conductive material, which are alternately stacked, and has a rectangular parallelepiped shape. A piezoelectric element that excites vibrations near a resonance frequency by displacement based on a piezoelectric transverse effect in a longitudinal direction of the body, wherein the driving body has a vibration generating portion and a terminal electrode portion, and the terminal electrode portion is a rectangular parallelepiped shape. In the vibration generating portion, the electrode layer is laminated on the entire surface of the piezoelectric layer, and in the terminal electrode portion, a pair of external electrodes are provided on one end surface, and a plurality of electrodes are provided. An ultrasonic vibration element in which a layer is electrically connected to one of a pair of external electrodes every other layer.

  In the ultrasonic vibration element according to [1], the electrode layer is laminated on the entire surface of the piezoelectric layer in the vibration generating portion, which means that the vibration generating portion is a full surface electrode type piezoelectric element. The terminal electrode part is provided on one end face side of the driving body having a rectangular parallelepiped shape, which means that the terminal electrode part is provided only on the one end face side of the driving body. Since it is not composed of a plane, it means that it is provided including one end face.

  That is, the ultrasonic vibration element according to [1] is a piezoelectric element in which a piezoelectric layer having electrodes stacked on the entire surface is continuously formed except for one end face where the terminal electrode portion is provided and its vicinity. It has become. Therefore, the displacement based on the piezoelectric lateral effect is not hindered in the portion other than the terminal electrode portion, that is, the vibration generating portion. In other words, the terminal electrode part is provided only on one end face side of the rectangular parallelepiped driving body that is a position that does not hinder the vibration of the vibration generating part, in which each of the pair of external electrodes is not short-circuited. In addition, it has a mode of conducting with every other electrode layer.

  The ultrasonic vibration element according to [1] is expressed as being connected to a plurality of electrode layers and a pair of external electrodes and approximately every other layer (alternately). This is because the vibration generating unit can be driven even when the layers are not separated. In a preferred embodiment, all electrode layers are laminated with alternate polarity (alternately).

  The ultrasonic vibration element according to [1] is a piezoelectric element that excites vibrations near a resonance frequency by a displacement based on a piezoelectric lateral effect in a longitudinal direction of a driving body having a rectangular parallelepiped shape. In addition to the case of resonance, an ultrasonic vibration element is used as a vibration source of an ultrasonic actuator described later, and an elastic body connected to the ultrasonic vibration element is excited by vibration of the ultrasonic vibration element. There is a case of resonance of the body or a case of resonance in which the ultrasonic vibration element and the elastic body vibrate together, and the mode of resonance is not limited to one.

  [2] The ultrasonic vibration element according to [1], wherein the electrode layer is laminated on one side of the piezoelectric layer in the terminal electrode portion.

  The ultrasonic vibration element according to [2] has a mode in which the electrode layer is laminated on only one surface of the piezoelectric layer in the terminal electrode portion, in other words, one end surface provided with an external electrode, and In the vicinity thereof, the polarity of the stacked electrode layers is only one of the polarities of the pair of external electrodes, and the pair of electrode layers does not sandwich the piezoelectric layer, that is, does not overlap. is there.

  [3] One electrode layer of the plurality of electrode layers is exposed at one end surface of the one end surface from the piezoelectric layer and is electrically connected to one of the pair of external electrodes. Other than the above, the other end of the plurality of electrode layers, which is embedded in the piezoelectric layer and insulated from the other of the pair of external electrodes, is one part of one end surface. The other end of the pair of external electrodes is exposed from the piezoelectric layer and is electrically connected to the other of the pair of external electrodes. The other end of the pair of external electrodes The ultrasonic vibration element according to [1] or [2], which is insulated from one side.

  The ultrasonic vibration element according to [3] shows a relationship between two unspecified electrode layers stacked adjacent to each other among a plurality of electrode layers. Specifically, it is specifically shown that conduction is made with one of the pair of external electrodes in every other layer.

  [4] Of two short directions perpendicular to the longitudinal direction of the driving body having a rectangular parallelepiped shape, the resonance frequency based on the piezoelectric longitudinal effect applied to the stacking direction of the piezoelectric layers corresponding to one short direction, and the other short sides The ultrasonic vibration element according to any one of [1] to [3], wherein a resonance frequency based on a piezoelectric lateral effect in the width direction of the piezoelectric layer corresponding to the direction is adjusted to be equal.

  In the ultrasonic vibration element according to [4], the width direction of the piezoelectric layer refers to a direction perpendicular to a direction (length direction) applied to the displacement in the piezoelectric layer.

  [5] One end face of the driving body on the side where the terminal electrode portion is provided is any one of both end faces in the direction of displacement of the driving body. [1] to [4] The ultrasonic vibration element as described.

  In the present specification, the both end faces in the direction of displacement (vibration) of the driving body are both end faces substantially perpendicular to the direction of displacement (vibration) of the driving body. Point to.

  [6] Two driving bodies having a rectangular parallelepiped shape are provided, and the two driving bodies join one end face, share a terminal electrode portion, and are integrally fired. Any one of [1] to [5] The ultrasonic vibration element according to any one of the above.

  The ultrasonic vibration element according to [6] is an ultrasonic vibration element that vibrates by being divided into two driving bodies (vibration generating units) with one end face as a symmetry plane.

  [7] A vibration detection unit that includes a piezoelectric layer and at least a pair of electrode layers provided between the piezoelectric layers and detects an electrical signal generated in the piezoelectric layer due to mechanical vibration by the pair of electrode layers. The ultrasonic vibration element according to any one of [1] to [6].

  The ultrasonic vibration element according to [7] is a suitable means when the use environment and use conditions change. In general, since an ultrasonic actuator using an ultrasonic vibration element changes its resonance frequency due to temperature fluctuations or load fluctuations, in order to maintain an optimum driving condition, it is applied to the ultrasonic vibration element while monitoring the vibration state. It is necessary to control the driving frequency. As a means for realizing this, there may be a method of indirectly detecting a vibration state by monitoring a change in driving current and feeding back to the control circuit. However, the ultrasonic vibration element described in [7] It is a means by which the frequency can be monitored.

  In the ultrasonic vibration element according to [7], a specific aspect of the vibration detection unit is not limited. Since it is easy to manufacture, it may be formed of the same components as the vibration generating portion of the driving body, or may have a different configuration. However, it serves as a sensor and cannot share the terminal electrode portion, and it is necessary to provide a dedicated terminal electrode portion for providing an external electrode and conducting with the electrode layer. In the ultrasonic vibration element according to [7], it is preferable that the whole including the vibration detection unit is baked and integrated. This is because the efficiency of generating vibration is increased.

  [8] A drive that has a plurality of piezoelectric layers made of piezoelectric material and a plurality of electrode layers made of a conductive material that are alternately stacked, and has a rectangular parallelepiped shape. A piezoelectric element that excites vibrations near a resonance frequency by a displacement based on a piezoelectric transverse effect in a longitudinal direction of the body, wherein the driving body has one terminal electrode part and two vibration generating parts, and one terminal The electrode part is provided in the approximate center of the driving body having a rectangular parallelepiped shape, and the second vibration generating part is provided on both sides of the terminal electrode part in the direction of displacement. In the vibration generating part, the electrode layer is the entire surface of the piezoelectric layer. In the terminal electrode portion, the electrode layer is laminated on one side of the piezoelectric layer, and a pair of external electrodes are provided on the end face parallel to the direction of displacement, and the plurality of electrode layers are arranged at every other layer. Conduction with one of a pair of external electrodes In which the ultrasonic vibration element.

  [8] The ultrasonic vibration element according to [8] is substantially the same as the one in which the two ultrasonic vibration elements according to [1] are integrated by sharing the terminal electrode portion, [6] The one substantially equivalent to the ultrasonic vibration element described in 1 is manufactured integrally from the beginning.

  A preferable aspect of the ultrasonic vibration element according to any one of [1] to [7] will be described below. In order to vibrate all the piezoelectric layers by displacement based on the piezoelectric lateral effect, the outermost layers of the driver are both electrode layers. At this time, in order to enhance the insulation between the electrode layer and the outside or the electrode layer, if necessary, the outermost electrode layer is coated with an insulator having excellent elasticity so as not to affect the displacement (vibration). It is also preferable. Examples of the insulator include rubber and resin.

  The ultrasonic vibration element according to any one of [1] to [7] preferably has a multilayer structure in which the number of stacked piezoelectric layers is 10 or more and 1000 or less. More desirably, the number of stacked layers is 30 or more and 300 or less. If it is less than 10 layers, there is a possibility that sufficient generated force may not be obtained, and if it exceeds 1000 layers, production becomes gradually difficult. The thickness of the electrode layer is preferably 0.1 μm or more and 10 μm or less. If it is thinner than 0.1 μm, it may be difficult to form a uniform electrode layer on the surface of the piezoelectric body. If it is thicker than 10 μm, it becomes difficult to deform the electrode and hinder displacement (vibration). Energy loss may increase. Furthermore, it is desirable that the cross section of the drive body having a rectangular parallelepiped shape is substantially square. This is because the transmission area of the generated force due to vibration is minimized, and stress due to deformation is evenly distributed to enhance durability.

  In the ultrasonic vibration element according to any one of [1] to [7], the ratio of the length and thickness of the piezoelectric layer is preferably 10: 1 to 1000: 1. The length indicates the dimension of the piezoelectric layer in the direction of displacement (vibration), and the thickness indicates the dimension of the piezoelectric layer in the direction of stacking (the dimension in the direction perpendicular to the direction of displacement (vibration) is called the width). . The length of the piezoelectric layer (driver) is preferably 1 mm or more and 50 mm or less, and more preferably 3 mm or more and 20 mm or less. If the length is less than 1 mm, the amount of displacement and the force that can be generated may be too small. If the length is longer than 50 mm, the strength decreases, so that it may be difficult to apply as a drive source of the ultrasonic actuator, and may be difficult to incorporate into the ultrasonic actuator. is there.

  [9] An elastic body and the ultrasonic vibration element according to any one of [1] to [7], wherein the ultrasonic vibration element is any of both end faces in the direction of displacement of the driving body. An ultrasonic actuator which is bonded to an elastic body on the side of one of the end faces and has a remaining surface free.

  [10] A connection means for connecting a pair of external electrodes provided in the terminal electrode portion of the ultrasonic vibration element and an external power source for applying a driving voltage to the pair of external electrodes is integrally formed with the elastic body. The ultrasonic actuator according to [9], which is formed.

  [11] An elastic body and the ultrasonic vibration element according to the above [7], wherein the ultrasonic vibration element is on either end face side of both end faces in the displacement direction of the driving body. It is bonded to an elastic body, and the remaining surface is free, and is connected to a pair of external electrodes provided in the terminal electrode portion of the ultrasonic vibration element and an external power source for applying a driving voltage to the pair of external electrodes. Connecting means for connecting the electrode layer provided in the vibration detection unit of the ultrasonic vibration element and an external power source for applying a driving voltage to the electrode layer integrally with the elastic body. The formed ultrasonic actuator.

  In the ultrasonic actuator according to any one of [9] to [11], the free remaining surface is not only an end surface to which an elastic body is not joined among both end surfaces in the direction of displacement (vibration) of the driving body. All the end surfaces except the end surface to which the elastic body is joined among the both end surfaces in the direction of displacement (vibration) of the driving body are indicated. That is, the remaining surface is free means that only the surface to which the elastic body is joined is constrained and all the remaining surfaces are not constrained.

  In the ultrasonic actuator according to [10] or [11], the connection means is integrally formed with the elastic body, and the connection means is not a means separated from an elastic body such as a lead wire, but is elastic, for example. It is a wiring pattern or the like provided on the body itself, and means a means inseparable from the elastic body.

  In the ultrasonic vibration element according to the above [1], since the entire vibration generating part excluding the terminal electrode part can vibrate without being restricted, the energy loss of vibration is extremely small. In addition, a pair of external electrodes connected to the electrode layer every other layer is a terminal electrode portion (one end face of the driving body) that does not hinder vibration due to displacement based on the piezoelectric lateral effect of the piezoelectric layer (vibration generating portion). On the other hand, the vibration generating portion has a structure in which the piezoelectric layer is sandwiched between electrode layers made of a conductive material having excellent durability against vibration. Therefore, even when a large amplitude vibration is driven in the vicinity of the resonance frequency, the deterioration of its own mechanical strength is extremely small and the characteristic deterioration hardly occurs. Furthermore, since the piezoelectric layer that generates and transmits vibration energy is continuously formed in the displacement (vibration) direction, it has excellent energy conversion efficiency and can easily achieve high output.

  The ultrasonic vibration element according to the above [1] is an ultrasonic vibration element that excites vibration by displacement based on a piezoelectric lateral effect. In the vibration generating part, the piezoelectric layer is sandwiched between electrode layers and the thickness of the piezoelectric layer is increased. Used with polarization in the vertical direction. The amount of displacement of the piezoelectric layer is determined by the length of the element, and it is not necessary to increase the number of piezoelectric layers stacked in order to increase the amount of displacement. Therefore, the manufacturing process becomes simpler and can be manufactured at a lower cost.

  In the ultrasonic vibration element according to the above [2], the electrode layer does not overlap with the piezoelectric layer sandwiched in the terminal electrode portion (one end face and its vicinity) provided with the external electrode. Accordingly, the piezoelectric layer does not exhibit displacement at the one end face and in the vicinity thereof, and unnecessary displacement restraint and energy loss can be avoided.

  According to the ultrasonic vibration element described in [3] above, electrical connection is established with every other electrode layer so that each of the pair of external electrodes in the ultrasonic vibration element described in [1] or [2] does not short-circuit. In order to realize such a mode, it is not necessary to separately provide an insulating portion, the manufacturing process is simplified, and the cost can be easily reduced.

  In the ultrasonic vibration element described in [4] above, the resonance frequency based on the piezoelectric longitudinal effect applied in the stacking direction of the piezoelectric layers is equal to the resonance frequency based on the piezoelectric transverse effect applied in the width direction of the piezoelectric layers. Since it is adjusted, the operation when used as a vibration source such as an ultrasonic actuator becomes more stable, and vibration energy loss becomes extremely small.

  In order to adjust the two resonance frequencies to be equal to each other, for example, the measurement of each resonance frequency by an impedance measuring instrument or the like and the grinding of the outer dimensions in the two lateral directions are repeatedly performed. Means such as matching frequencies can be employed. It cannot be realized simply by combining the two lateral dimensions. This is due to the following reason.

  In a conventional multilayer piezoelectric element that uses displacement based on the piezoelectric longitudinal effect that does not belong to the present invention, it corresponds to the expansion and contraction operation in the stacking direction (the main axis direction in the case of a rectangular parallelepiped, corresponding to the longitudinal direction in the present invention) In the biaxial direction perpendicular to the stacking direction (corresponding to the two short directions in the present invention), expansion and contraction occurs due to the piezoelectric lateral effect. For example, a laminated piezoelectric element having a rectangular parallelepiped shape, the same width and thickness, a large length (for example, 5 mm wide × 5 mm thick × 10 mm long) and stacked in the length direction In this case, the length direction is the stacking direction (corresponding to the longitudinal direction in the present invention), and the short direction (biaxial direction) perpendicular to the stacking direction (main axis direction) is displaced based on the same piezoelectric lateral effect. Therefore, by making the width and thickness of the laminated piezoelectric element equal as in this example, it is possible to match the resonance frequencies of vibrations in the biaxial direction (short direction).

  However, even when the outer shape is a rectangular parallelepiped, the width and thickness are the same size and the length is large (for example, width 5 mm × thickness 5 mm × length 10 mm), the ultrasonic wave according to the present invention is used. In the vibration element, it is not laminated in the length direction but in the thickness direction, the length direction (longitudinal direction) is the direction of displacement (vibration), and the longitudinal direction (main axis direction is not the lamination direction) The thickness direction (stacking direction) as an ultrasonic vibration element expresses displacement based on the piezoelectric longitudinal effect, and the width direction expresses displacement based on the piezoelectric transverse effect. However, the displacement is different. In addition, since the width direction is composed of only a piezoelectric layer, the thickness direction is a laminated structure of a piezoelectric layer and an electrode layer, so the width and thickness of the ultrasonic vibration element are the same. However, their resonance frequencies do not match. Therefore, if only the outer dimensions are matched as in the conventional multilayer piezoelectric element, a complicated vibration mode is likely to be induced and stable operation may be difficult. The ultrasonic vibration element according to the above [4] is characterized by solving this problem.

  The ultrasonic vibration element according to the above [7] is obtained by adding a vibration detection unit to the ultrasonic vibration element according to the above [1] to [6] as a constituent element. The vibration state of the vibration generating section) can be accurately and directly detected and fed back to a predetermined control circuit. Even if the resonance frequency shifts due to load fluctuations or temperature fluctuations, it is possible to maintain optimum driving conditions.

  The ultrasonic actuator according to [9] is an actuator in which the ultrasonic vibration element according to [1] to [7] is bonded to an elastic body, and both end faces of the ultrasonic vibration element in the vibration direction. One of the end faces is characterized in that it is joined so as to vibrate freely. Accordingly, since it can be regarded as a continuous monolithic structure of a piezoelectric layer made of a piezoelectric material in the direction of propagation of vibration to the elastic body, resonance energy can be transmitted efficiently. In addition, since both sides of the piezoelectric layer are reinforced by electrode layers, it has excellent mechanical strength against tensile and compressive stress acting on the ultrasonic vibration element during large amplitude vibration due to resonance. Demonstrate. In addition, even if the drive voltage is increased, the mechanical quality factor does not decrease, and it is possible to efficiently excite large-amplitude vibration by vibrating near the resonance frequency.

  The ultrasonic actuator according to the above [10] does not use means separated from an elastic body such as a lead wire as a wiring means for applying a drive signal to the ultrasonic vibration element. The change of the resonance condition and energy loss of the ultrasonic vibration element due to the addition cannot occur. In the ultrasonic actuator described in [10] above, the minimum connection means such as soldering may be used on the joint surface between the elastic body and the ultrasonic vibration element, and the variation in the resonance conditions of the ultrasonic vibration element is extremely small. As a result, the ultrasonic vibration element can be efficiently driven.

  In the ultrasonic actuator according to [11], in addition to the aspect of the ultrasonic actuator according to [10], when an ultrasonic vibration element including a vibration detection unit is used, an electrode provided in the vibration detection unit The ultrasonic actuator according to [10], wherein the connection means for conducting the layer and an external power source for applying a driving voltage to the electrode layer is formed integrally with the elastic body. According to the above effect, even if the vibration detection unit is provided, the variation in the resonance condition of the ultrasonic vibration element is suppressed to be extremely small, and as a result, the ultrasonic vibration element can be driven efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. However, the present invention should not be construed as being limited to these, and those skilled in the art will be able to do so without departing from the scope of the present invention. Various changes, modifications and improvements can be made based on the knowledge. For example, the drawings show preferred embodiments of the present invention, but the present invention is not limited by the modes shown in the drawings or the information shown in the drawings. In practicing or verifying the present invention, means similar to or equivalent to those described in the present specification can be applied, but preferred means are those described below.

  First, the ultrasonic vibration element according to the present invention will be described. In general, the term “stacked piezoelectric element” refers to a piezoelectric element that can increase displacement by increasing the number of stacked layers, and that exhibits displacement based on the piezoelectric longitudinal effect. Is a laminated piezoelectric element that excites vibration by displacement based on the piezoelectric lateral effect, and can increase displacement by increasing the length of the piezoelectric layer regardless of the number of laminated layers It is. The ultrasonic vibration element according to the present invention is a piezoelectric element that includes a drive body having a rectangular parallelepiped shape and excites vibrations near the resonance frequency by displacement based on the piezoelectric lateral effect in the longitudinal direction of the drive body. The driving body has a vibration generating portion and a terminal electrode portion, and the terminal electrode portion is provided on one end face side of the driving body having a rectangular parallelepiped shape, and the electrode layer is provided on the entire surface of the piezoelectric layer in the vibration generating portion. In the terminal electrode portion, a pair of external electrodes are provided on one end face, and the plurality of electrode layers are electrically connected to any one of the pair of external electrodes in every other layer.

  An example of an embodiment of an ultrasonic vibration element according to the present invention is shown in FIG. The ultrasonic vibration element 40 shown in FIG. 4 is a piezoelectric element that excites vibrations near the resonance frequency by displacement based on the piezoelectric lateral effect. The ultrasonic vibration element 40 includes a plurality of piezoelectric layers 44 made of a piezoelectric material and a plurality of electrode layers 48 and 49 made of a conductive material, which are alternately stacked. The ultrasonic vibration element 40 includes a drive body 41 having a rectangular parallelepiped shape. The drive body 41 includes a vibration generation unit 46 and a terminal electrode unit 47, and the terminal electrode unit 47 is connected to the drive unit 41. It is provided on the side of one end face. The one end face is one of the two end faces in the direction of displacement (vibration) of the drive body 41. That is, the drive body 41 (ultrasonic vibration element 40) vibrates in the S direction (arrow in FIG. 4). One end face is provided with a pair of external electrodes 58 and 59, connected to an external power source (not shown) via the external electrodes 58 and 59, and a voltage is applied between the electrode layers 48 and 49.

  The electrode layers 48 and 49 are electrically connected to the pair of external electrodes 58 and 59 in every other layer in the terminal electrode portion 47. In the ultrasonic vibration element 40, the electrode layers 48 and 49 are laminated on the entire surface of the piezoelectric layer 44 in the vibration generating portion 46 of the driving body 41, but the electrode layers 48 and 49 are piezoelectric in the terminal electrode portion 47. The layers 44 are laminated only on one side, and the electrode layers 48 and 49 do not overlap. In the terminal electrode portion 47, one of the electrode layers 48, 49 has an end exposed from the piezoelectric layer 44 in the vicinity of the external electrode 58 and is electrically connected to the external electrode 58, but in the vicinity of the external electrode 58. Except for the portion, the end portion is embedded in the piezoelectric layer 44 and is not electrically connected (insulated) to the external electrode 59. On the other hand, the electrode layer 49, which is one layer from the electrode layer 48, exposes the end from the piezoelectric layer 44 in the vicinity of the external electrode 59 and is electrically connected to the external electrode 59. The end portion is embedded in the piezoelectric layer 44 and is not electrically connected (insulated) to the external electrode 58.

  The ultrasonic vibration element 40 includes a non-operating portion 45 that includes only the piezoelectric layer 44 and is not laminated with the electrode layers 48 and 49, in addition to the drive body 41 having the vibration generating portion 46 and the terminal electrode portion 47. The non-operating portion 45 is provided on the side opposite to the end surface where the terminal electrode portion 47 is provided. That is, similarly to the terminal electrode portion 47, since it is provided on one of the end faces in the direction of displacement (vibration) of the drive body 41, the vibration of the drive body 41 (ultrasonic vibration element 40). Not disturb. The non-operation unit 45 plays a role of protecting the ultrasonic vibration element 40.

  In the ultrasonic vibration element 40 shown in FIG. 4, the number of stacked piezoelectric layers 44 is 13. This is for the sake of convenience, giving priority to improving the visual understanding of the structure in the drawing. As described above, a larger number of layers is desirable. Further, the thickness of the electrode layers 48 and 49 is indicated by D1 in FIG. 4, the thickness of the piezoelectric layer 44 is indicated by D2, and the length of the piezoelectric layer 44 is indicated by L1 and L2. L2 indicates the entire length of the piezoelectric layer 44 regardless of whether or not the electrode layers 48 and 49 are stacked. L1 indicates a piezoelectric layer applied to the vibration generating unit 46 in which the electrode layers 48 and 49 are stacked on the entire surface of the piezoelectric layer 44. The length of 44 is shown. In designing the ratio of the length and thickness of the piezoelectric layer, the length indicates the dimension of the piezoelectric layer in the direction of displacement (vibration), and therefore the length indicates L2. Usually, as a preferred embodiment, the length L2 is increased with respect to the thickness D2 of the piezoelectric layer 44, and the lengths of the terminal electrode portion 47 and the non-operation portion 45 are suppressed. Therefore, in L1 / D2 and L2 / D2, There is almost no difference.

  Another example of the embodiment of the ultrasonic vibration element according to the present invention is shown in FIGS. 7 (a) and 7 (b). The ultrasonic vibration element 71 shown in FIG. 7A is obtained by removing the non-operation part 45 from the ultrasonic vibration element 40. When protection is not necessary, the ultrasonic vibration element 71 can be further downsized.

  The ultrasonic vibration element 72 shown in FIG. 7B includes two driving bodies 41, which join one end face 55 and separate the vibration generating section 46 but share the terminal electrode section 47. And fired and integrated. That is, two ultrasonic vibration elements 71 are integrated. Also in the ultrasonic vibration element 72, the two vibration generating parts 46 except the terminal electrode part 47 located at the center are not restrained at all, and no energy loss of vibration occurs.

  Of course, the ultrasonic vibration element 72 can be manufactured integrally from the beginning, and can be regarded as one drive body having one terminal electrode portion 47 and two vibration generation portions 46. In other words, in the ultrasonic vibration element 72, one terminal electrode portion 47 is provided in the approximate center of one driving body having a rectangular parallelepiped shape, and the second vibration generating portion 46 is in the S direction of displacement (vibration). Provided on both sides of the terminal electrode portion 47. In the vibration generating portion 46, the electrode layers 48 and 49 are laminated on the entire surface of the piezoelectric layer 44. In the terminal electrode portion 47, the electrode layers 48 and 49 are piezoelectric. The layer 44 is laminated on one side. In the terminal electrode portion 47, a pair of external electrodes 58 and 59 are provided on end faces parallel to the S direction of displacement (vibration), and the plurality of electrode layers 48 and 49 are arranged in pairs every other layer. , 59 is electrically connected.

  Next, means for adjusting the resonance frequencies in the two short directions in the ultrasonic vibration element according to the present invention having a rectangular parallelepiped shape will be described. In the ultrasonic vibration element according to the present invention, the measurement of each resonance frequency by the impedance measuring instrument and the grinding of the outer dimensions in the two short directions can be repeatedly performed to match the two resonance frequencies.

  First, an ultrasonic vibration element according to the present invention having a rectangular parallelepiped shape and having the same width and thickness and a large length is manufactured. For example, it is an ultrasonic vibration element having the same form as the ultrasonic vibration element 40 shown in FIG. 4, the outer dimensions are different from those of the ultrasonic vibration element 40, and the S direction (displacement ( 4 is the longitudinal direction (length direction) having the largest dimension, and is the thickness direction (one short direction and the stacking direction of the piezoelectric layer 44) as a rectangular parallelepiped ultrasonic vibration element. The ultrasonic vibration element having the same dimension in the vertical direction) and the width direction (the other short direction, the left depth direction in FIG. 4) corresponds to this.

  In the ultrasonic vibration element according to the present invention having the same dimensions as the width and thickness, the resonance frequencies in the two lateral directions (thickness direction and width direction) do not match. FIG. 10 is a graph showing an example in which the resonance frequencies do not coincide with each other, and an impedance measuring device is used for the ultrasonic transducer element according to the present invention having a rectangular parallelepiped shape whose outer dimensions are width 5 mm × thickness 5 mm × length 10 mm. The graph showing the result of measuring the frequency characteristics of impedance. In FIG. 10, peak 1 corresponds to resonance vibration in the longitudinal direction (length direction), and peak 2 and peak 3 correspond to resonance vibrations in two lateral directions (width direction and thickness direction), respectively. Peak 2 is the resonance in the width direction based on the piezoelectric transverse effect, and peak 3 is the resonance in the thickness direction (stacking direction) based on the piezoelectric longitudinal effect. Even if the width and thickness are the same, the resonance frequencies do not match. It is shown.

  The ultrasonic vibration element having the same width and thickness dimensions is measured by measuring the resonance frequency with an impedance measuring instrument while shortening the width direction dimension by grinding. Confirm that the peak shifts to the side, and adjust so that peak 2 and peak 3 overlap. To shorten the dimension in the width direction by grinding means, for example, that the surface where the piezoelectric layer 44 of the ultrasonic vibration element 40 shown in FIG. 4 is exposed, that is, the surface on the right depth side in FIG. In other words, an ultrasonic vibration element that originally has the same width and thickness is processed into an ultrasonic vibration element whose width is smaller (shorter) than the thickness, such as the ultrasonic vibration element 40. It means to go.

  FIG. 11 is a graph showing an example in which the resonance frequencies coincide as a result of the adjustment. 10 shows that the frequencies of peak 2 and peak 3 in FIG. 10 are equal to each other and peak 5 in FIG. 11 is obtained. In FIG. 11, the peaks as seen in the vicinity of peak 2 and peak 3 in FIG. It can be seen that the graph has a simple shape. This eliminates the complicated vibration mode in the vicinity of the peak 2 and peak 3 frequencies in FIG. 10, and the operation stability is improved when the ultrasonic vibration element according to the present invention is used as a vibration source such as an ultrasonic actuator. This indirectly indicates that vibration energy loss is greatly suppressed.

  Next, the ultrasonic actuator according to the present invention will be described. An example of an embodiment of an ultrasonic actuator according to the present invention is shown in FIG. The ultrasonic actuator 50 shown in FIG. 5 has an elastic body 61 and two ultrasonic vibration elements 62, which are coupled so as to form a Y shape as a whole. The ultrasonic actuator 50 that forms a Y-shaped non-linear coupling uses the ultrasonic vibration element 62 as a drive source, excites the combined vibration of longitudinal vibration and bending vibration as a whole, and generates a motion that draws an elliptical locus. It becomes a power source for the motor (for example, see Non-Patent Document 1 for the principle). In the ultrasonic actuator 50, each of the two ultrasonic vibration elements 62 is joined to the elastic body 61 on either end face side of both end faces in the S direction of displacement (vibration) of the drive body 41, and The remaining surface is free.

  The ultrasonic vibration element 62 constituting the ultrasonic actuator 50 includes a vibration detection unit 63 via a non-operation unit 65 in addition to the drive unit 41 (vibration generation unit and terminal electrode unit). The vibration detection unit 63 includes a piezoelectric layer and at least a pair of electrode layers provided between the piezoelectric layers, and constitutes a piezoelectric element. An electric signal generated in the piezoelectric layer due to mechanical vibration. Is detected by a pair of electrode layers. That is, the drive unit 41 performs electrical / mechanical conversion to generate vibration, and the vibration detection unit 63 performs mechanical / electrical conversion based on the piezoelectric effect to detect the vibration as an electrical constant. The vibration detection unit 63 may have the same structure as the drive unit 41 because it is easy to manufacture. Further, it may be composed of piezoelectric elements of other modes, for example, adopting stacked piezoelectric elements 30 and 31 driven by displacement based on the piezoelectric longitudinal effect shown in FIGS. 3 (a) and 3 (b). May be.

  In the ultrasonic actuator 50, each of the two ultrasonic vibration elements 62 is joined to the elastic body 61 on the vibration detection unit 63 side. However, the ultrasonic actuator according to the present invention is an elastic body on the drive unit side. An ultrasonic vibration element that is not provided with a vibration detection unit may be used. In the ultrasonic actuator 50, a lead wire 66 is used as a connection means with an external power source. However, like the ultrasonic actuator 50, the ultrasonic vibration element 62 is bonded to the elastic body 61 on the vibration detection unit 63 side. If there is a wiring pattern for conducting electrical connection between the electrode layer provided in the vibration detector 63 and an external power source for applying a driving voltage to the electrode layer, the elastic body 61 (inside or on the outer surface of the elastic body 61). ) Can be provided. In addition, when the elastic body 61 is joined on the drive unit 41 side, a pair of external electrodes provided in the terminal electrode unit of the drive unit 41 and an external power source for applying a drive voltage to the pair of external electrodes; It is possible to provide the elastic body 61 with a wiring pattern for conducting the above.

  Next, a method for manufacturing the ultrasonic vibration element according to the present invention will be described. An example of a schematic process of the method for manufacturing the ultrasonic vibration element according to the present invention is shown in FIGS. 6 (a) to 6 (c).

  First, a predetermined number of green sheets (hereinafter, also simply referred to as “sheets”) having a desired thickness mainly composed of a piezoelectric material are prepared. The green sheet can be produced by a conventionally known production method. For example, a piezoelectric material powder made of ceramics is prepared, and a slurry is prepared by preparing a binder, a solvent, a dispersant, a plasticizer and the like in a desired composition, and after defoaming treatment, a doctor blade method, a reverse roll A sheet can be formed by a sheet forming method such as a coater method.

  Then, an electrode paste made of a conductive material is applied to the sheet with a desired thickness by a printing method to produce approximately the same number of sheets 16 and sheets 17 each having flag-shaped electrode patterns 148 and 149 formed in different directions. (See FIG. 6 (a)). The electrode paste applied with the electrode pattern 148 of the sheet 16 (the flag flag portion 141 with the flag pole portion 141 being located at the lower left in the figure) is later formed into the electrode layer 48, and the electrode pattern 149 of the sheet 17 (the flag pole portion 142 is shown in the figure). The electrode paste painted in the left-facing flag shape located in the lower right of the middle becomes the electrode layer 49 later.

  In addition, according to the manufacture of the ultrasonic vibration element according to the present invention, it is preferable that the electrode pattern is such that the flagpole portions do not overlap when the sheets on which the electrode pattern is formed are laminated, such as the electrode patterns 148 and 149. . FIG. 9 shows an example in which flagpole portions overlap. In the sheet 216 and the sheet 217 shown in FIG. 9 in which the electrode patterns 248 and 249 are respectively formed, the flagpole portions 241 and 242 overlap each other in the overlapping portions 243 when stacked. Since the superimposing portion 243 is an electrode layer that sandwiches both surfaces of the piezoelectric layer later as an ultrasonic vibration element, it constitutes a portion where displacement can occur. On the other hand, since the flagpole parts 241 and 242 except for the superimposing part 243 do not overlap with each other, they constitute a part that does not generate displacement, and this part may cause a large internal stress and destroy the ultrasonic vibration element. Energy loss will occur. These problems can be avoided if an electrode pattern is formed so that the flagpole portions do not overlap when the sheets are stacked.

  Next, an adhesive paste made of the same piezoelectric material as the sheets is applied to the surfaces of the sheets 16 and 17 with a predetermined thickness, a desired number of layers are laminated, integrated by thermocompression bonding, and fired to obtain a laminate 70. (See FIG. 6 (b)).

  Then, after cutting along the cutting line 75 by a slicing method or other various machining processes, the pair of external electrodes 58 and 59 are formed on the end faces of the electrode patterns 148 and 149 on the flag pole portions 141 and 142 side in the laminated body 70. Then, the lead wire 66 is attached (see FIG. 6C). The external electrode 58 is electrically connected only to the electrode layer 48 via the flag pole portion 141, while not electrically connected to the electrode layer 49 (insulated). The external electrode 59 is electrically connected only to the electrode layer 49 via the flag pole part 142, while not electrically connected to the electrode layer 48 (insulated). Then, if a polarization process is performed as needed, the ultrasonic vibration element 60 will be obtained.

  Next, a method for manufacturing the ultrasonic actuator according to the present invention will be described. The ultrasonic actuator can be obtained by bonding the ultrasonic vibration element produced by the above method to an elastic body prepared separately. The means for joining the ultrasonic vibration element and the elastic body is not particularly limited, but a method of bonding using an adhesive such as an epoxy resin is suitable. In order to reduce the loss of vibration energy transmitted from the ultrasonic vibration element to the elastic body, it is desirable to bond the bonding surfaces with a minimum amount of adhesive, and for long-time ultrasonic vibration. It is desirable to select the joining conditions to withstand.

  Next, materials used for the ultrasonic vibration element and the ultrasonic actuator according to the present invention will be described. The piezoelectric material constituting the piezoelectric layer is not limited. A preferred piezoelectric material is piezoelectric ceramics in a broad sense. In the broad sense of piezoelectric ceramics, in addition to narrowly defined piezoelectric ceramic materials, electrostrictive ceramic materials, ferroelectric ceramic materials that exhibit polarization reversal, and antiferroelectric properties in which a phase transition between the antiferroelectric phase and the ferroelectric phase is observed. Body ceramic materials, and the like.

  Examples of piezoelectric ceramics include lead zirconate titanate, lead magnesium niobate (PMN), lead nickel niobate (PNN), lead zinc niobate, lead manganate niobate, lead antimony stannate, lead manganese tungstate, Ceramic materials containing lead cobalt niobate, barium titanate, sodium bismuth titanate, bismuth neodymium titanate (BNT), potassium sodium niobate, strontium bismuth tantalate alone, as a mixture, or as a solid solution It is done. In addition, lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium, bismuth, tin, etc. It is also preferable to add a substance or the like alone or in admixture. This is because there are cases where advantages such as adjustment of piezoelectric characteristics can be obtained.

  The conductive material constituting the electrode layer is not limited. For example, metals such as nickel, copper, palladium, silver, titanium, chromium, tantalum, hafnium, cobalt, zinc, zirconium, niobium, molybdenum, tungsten, iridium, magnesium, ruthenium may be used alone, or silver- You may use alloys, such as palladium, silver-platinum, silver-gold, nickel-gold, and nickel-silver.

  The material of the elastic body that constitutes the ultrasonic actuator together with the ultrasonic vibration element is selected depending on the output torque and speed required for the ultrasonic motor. For example, metal materials such as aluminum, ceramic materials such as alumina and zirconia, etc. Can be adopted.

  The ultrasonic actuator according to the present invention is suitable for controlling an ultrasonic motor operated near the resonance frequency to an optimum driving condition, and is particularly preferably used for a linear ultrasonic motor. The ultrasonic vibration element according to the present invention is suitably used as a drive source for such an ultrasonic actuator.

It is a perspective view showing an example of an actuator type ultrasonic motor. It is a side view showing other examples of an actuator type ultrasonic motor. FIG. 3A and FIG. 3B are cross-sectional views illustrating a piezoelectric longitudinal effect driving multilayer piezoelectric element used as a conventional vibration element. 1 is a perspective view showing an embodiment of an ultrasonic vibration element according to the present invention. It is a side view showing one embodiment of the ultrasonic actuator concerning the present invention. FIG. 6A to FIG. 6C are explanatory views showing an example of a schematic process of the method for manufacturing the ultrasonic vibration element according to the present invention. FIG. 7A and FIG. 7B are perspective views showing another embodiment of the ultrasonic vibration element according to the present invention. FIG. 8A to FIG. 8C are perspective views illustrating a multilayer piezoelectric element that is not suitable as an ultrasonic vibration element obtained in the course of the applicant's research. It is explanatory drawing which shows the schematic process of the method of manufacturing an ultrasonic vibration element, and shows an example in which the flagpole part of the electrode pattern formed on the green sheet overlaps. 5 is a graph showing impedance frequency characteristics in an example in which resonance frequencies in two short directions perpendicular to the longitudinal direction (major axis direction) do not match in the ultrasonic vibration element according to the present invention having a rectangular parallelepiped shape. 6 is a graph showing impedance frequency characteristics in an example in which resonance frequencies in two short directions perpendicular to the longitudinal direction (major axis direction) coincide in the ultrasonic vibration element according to the present invention having a rectangular parallelepiped shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Y type ultrasonic linear actuator, 11 ... Vibration element, 12, 22, 61 ... Elastic body, 13, 23 ... Driven body, 14, 44 ... Piezoelectric layer, 16, 17 ... Green sheet, 18, 19, 48 , 49 ... electrode layer, 20 ... π-type ultrasonic linear actuator, 28, 29, 58, 59, 78, 79 ... external electrodes, 30, 31, 81, 82, 83 ... stacked piezoelectric elements, 40, 60, 62 , 71, 72 ... ultrasonic vibration element, 41 ... drive unit, 45, 65, 85 ... non-operation unit, 46, 76 ... vibration generation unit, 47 ... terminal electrode unit, 50 ... ultrasonic actuator, 63 ... vibration detection unit , 66 ... lead wire, 70 ... laminate, 75 ... cutting line, 141, 142, 241, 242 ... flagpole part, 148, 149, 248, 249 ... electrode pattern, 243 ... overlapping part.

Claims (8)

A plurality of piezoelectric layers made of a piezoelectric material and a plurality of electrode layers made of a conductive material, which are alternately stacked, are composed of a driving body having a rectangular parallelepiped shape, and the length of the driving body exhibiting the rectangular parallelepiped shape A piezoelectric element that excites vibrations near a resonance frequency by displacement based on a piezoelectric lateral effect in a direction,
The driving body has a vibration generating portion and the terminal electrode portion, the terminal electrode portion is Rutotomoni provided on the side of one end face of the driver exhibiting the rectangular parallelepiped, driver exhibiting the rectangular shape Provided with two, the two driving bodies are joined by firing, joining the one end face, sharing the terminal electrode portion,
In the vibration generating portion, the electrode layer is laminated on the entire surface of the piezoelectric layer,
In the terminal electrode portion, the electrode layer is laminated on one surface of the piezoelectric layer, and in the terminal electrode portion, a pair of external electrodes are provided on the one end surface, and the plurality of electrode layers are substantially one layer. An ultrasonic vibration element that is electrically connected to any one of the pair of external electrodes. One electrode layer of the plurality of electrode layers is
In one portion of the one end surface, the end portion is exposed from the piezoelectric layer to be electrically connected to one of the pair of external electrodes, and in one portion other than the one end surface, the end portion is connected to the piezoelectric layer. Embedded and insulated from the other of the pair of external electrodes,
Of the plurality of electrode layers, another electrode layer that is substantially one layer from the one electrode layer,
In the other part of the one end face apart from the one part, the end is exposed from the piezoelectric layer and is electrically connected to the other of the pair of external electrodes. The ultrasonic vibration element according to claim 1, wherein an end portion is embedded in the piezoelectric layer and insulated from one of the pair of external electrodes.   Among the two short directions perpendicular to the longitudinal direction of the driving body having the rectangular parallelepiped shape, the resonance frequency based on the piezoelectric longitudinal effect in the lamination direction of the piezoelectric layer corresponding to one short direction, and the other short direction The ultrasonic vibration element according to claim 1, wherein a resonance frequency based on a piezoelectric transverse effect applied in a width direction of the piezoelectric layer corresponding to the piezoelectric layer is adjusted to be equal.   The one end face of the driving body on the side where the terminal electrode portion is provided is any one of both end faces in the direction of displacement of the driving body. Ultrasonic vibration element. A vibration detection unit that includes a piezoelectric layer and at least a pair of electrode layers provided between the piezoelectric layers, and detects an electric signal generated in the piezoelectric layer due to mechanical vibration by the pair of electrode layers. Item 5. The ultrasonic vibration element according to any one of Items 1 to 4 . It has an elastic body and the ultrasonic vibration element as described in any one of Claims 1-5 , and the said ultrasonic vibration element is any one of the both end surfaces concerning the displacement direction of the said drive body. An ultrasonic actuator which is bonded to the elastic body on the end face side and has a free remaining surface. Connection means for conducting a pair of external electrodes provided in the terminal electrode portion of the ultrasonic vibration element and an external power source for applying a driving voltage to the pair of external electrodes is formed integrally with the elastic body. The ultrasonic actuator according to claim 6 . An elastic body and the ultrasonic vibration element according to claim 5 , wherein the ultrasonic vibration element has the elasticity on one end face side of both end faces in the direction of displacement of the driving body. It is bonded to the body, and the remaining surface is free, and is connected to a pair of external electrodes provided in the terminal electrode portion of the ultrasonic vibration element and an external power source for applying a driving voltage to the pair of external electrodes. A connecting means for connecting the electrode layer provided in the vibration detecting unit of the ultrasonic vibration element and an external power source for applying a driving voltage to the electrode layer. Formed ultrasonic actuator.

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