JP2006174680A - Oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the facing opposite ends of a piezoelectric oscillator drive, which moves in a lower-order mode of vibration, in an elliptical motion in the directions opposite to each other by a large driving force. <P>SOLUTION: The piezoelectric oscillator 10 has a plate-like piezoelectric elements 20, 20 and a shim. The piezoelectric elements 20, 20 are polarized in the thickness direction and have a first and second projection parts 21a, 21b which extend from center to both sides along a first direction D1. The tip ends of the first and second projection parts 21a, 21b have side parts 22 parallel to a second direction D2. A third and fourth projection parts 21c, 21d are formed on the piezoelectric elements 20, 20, so that each projection part reduces its width, as they extend from the center along the second direction D2. An electrode is provided on the surfaces of the piezoelectric elements 20, 20 and is divided into two or more along the second direction, to form the first and second electrodes 23a, 23b. The first and second electrodes 23a, 23b are applied with an AC voltage that has different phase and makes the side parts 22 move in an ellipse. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vibrator for driving an ultrasonic motor or the like.

  2. Description of the Related Art Conventionally, there is known an ultrasonic motor that is driven by vibrating a plate-like vibrator (hereinafter, unless otherwise noted, vibration refers to in-plane vibration of the plate-like vibrator). A lens barrel drive device to which such an ultrasonic motor is applied is disclosed (Patent Document 1). In this lens barrel driving device, an elliptical motion is performed on one point on the outer periphery of the disk by using a symmetrical vibration (R, 1) mode and an asymmetric vibration (1, 1) mode in which the perforated disk vibrator expands and contracts. The point of elliptical movement of the perforated disk vibrator is pressed from the direction parallel to the optical axis against the rotating body that rotates coaxially with the optical axis of the lens, and the rotating body is rotated. It is possible to move the lens in the optical axis direction by converting it into a linear motion in the optical axis direction.

  Further, it is disclosed that the linear motor is driven using the symmetric vibration (R, 1) mode and the asymmetric vibration (1, 1) mode of the above-described perforated disk vibrator (Non-patent Document 1). In this linear motor, elliptical motions whose rotational directions are opposite to each other by overlapping two contact portions provided on the outer circumference on one diameter of the perforated disk vibrator with tangential displacement in the same direction as radial expansion and contraction in the radial direction. In this way, the guide provided on the moving body is pressurized toward the two contact portions, and a driving force in the tangential direction is applied to the moving body to linearly drive the moving body.

  In general, in an ultrasonic motor, the output is increased by driving the vibrator in a resonance state, and it is practically necessary to match the resonance frequencies of two vibrations that are substantially orthogonal to each other when elliptically moving. In the perforated disk vibrator, a hole having a predetermined diameter is provided in the center of the disk in order to match the resonance frequencies of the symmetric vibration (R, 1) mode and the asymmetric vibration (1, 1) mode.

  Since such a perforated disk vibrator uses a low-order in-plane vibration mode, it is less affected by the position error of the electrode and can obtain a stable vibration. Therefore, since the counterpart member can be driven in the same direction, the vibrator is suitable for application to the linear motor disclosed in (Non-Patent Document 1).

However, when pressurizing the rotating body or the moving body, a relatively large circumferential tensile stress acts on the inside of the hole. Therefore, for example, when a piezoelectric ceramic such as PZT is used for the vibration generating member, a strong pressing force cannot be applied to the rotating body or the like from the vibrator because the tensile strength of the piezoelectric ceramic is weak. When the pressing force is weak, the frictional force between the vibrator and the rotating body is reduced, and the driving force cannot be increased.
JP-A-11-275878 Takahiro Masuda and two others, “Piezoelectric Linear Motor Uzing (R, 1)-((1,1)) Mode Disc Equiped With Tee Type Support Jigs For Realizing It Fine Performance (Piezoelectric Linear Motor Using (R, 1)-((1,1)) Mode Disk Equipped with T-Type Support Jigs for Realizing its Fine Performance), Japanese Journal of・ Applied Physics, The Japan Society of Applied Physics, 2004, Vol. 43, no. 5B, p. 2879-2883

  Accordingly, an object of the present invention is to provide a vibrator that is resistant to tensile stress and generates elliptical motions in opposite directions at both ends that expand and contract.

  The vibrator according to the present invention includes first and second protrusions having sides parallel to a second direction perpendicular to the first direction extending from the center of the vibrator to both sides along the first direction. The third and fourth protrusions extending on both sides along the second direction from the first to the second electrodes, and are vibrated by applying alternating voltages having different phases to the first and second electrodes, respectively. According to such a configuration, the first and second protrusions can be elliptically moved in directions opposite to each other without providing a hole in the vibrator.

  Moreover, it is preferable that an electrode is further provided between the first and second electrodes.

  Moreover, it is preferable that a width | variety becomes small as a 3rd, 4th protrusion part extends along a 2nd direction from the center. Moreover, it is preferable that a 1st protrusion part is formed of two sides parallel to a side part and a 1st direction. Furthermore, it is preferable that the distance between the tip of the third protrusion and the tip of the fourth protrusion is shorter than the distance between the tip of the first protrusion and the tip of the second protrusion. With such a configuration, it is possible to reduce the size in the second direction of the vibrator and the size in the second direction including the support member as described later.

  Further, a third electrode is provided between the first and second electrodes, and the phase of the AC voltage applied to one of the first and second electrodes is 90 ° and the other is applied to the other. It is preferable to apply an AC voltage whose phase is -90 ° different from that of the AC voltage. With such a configuration, the first vibration mode is driven by the third electrode as the center electrode, and the second vibration mode is driven by the two outermost electrodes, the first and second electrodes, respectively. These electrodes can be configured with a simple circuit.

  Each of the third and fourth protrusions includes first and second support members for supporting the piezoelectric vibrator on a piezoelectric vibrator support body provided with the piezoelectric vibrator, and the first support member The first connecting point for connecting the piezoelectric vibrator and the first support member is a straight line passing through the vibration center, which is the point where the vibration in the second direction of the piezoelectric vibrator is the largest, and in the second direction. Provided at a position deviating from the parallel straight line, the second support member connecting the piezoelectric vibrator and the second support member to the second support member at a position deviating from the straight line parallel to the second direction passing through the vibration center. It is preferable to be provided.

  Further, a plate-like vibrating body having first and second projecting portions and first and second electrodes and vibrating by applying an AC voltage, and a first and It is preferable to provide an elastic plate member having an adjustment portion extending outward from the second protrusion, and it is preferable that both ends of the elastic plate member along the first direction are formed in parallel with the second direction. Furthermore, the elastic plate member is preferably provided with a contact portion that protrudes outward from both ends along the first direction.

  In addition, the elastic plate member having the first to fourth projecting portions, the length in the first direction is longer than the width in the second direction, the first and second electrodes are in close contact with the elastic plate member, and an AC voltage is applied. It is preferable to include a plate-like vibrating body that vibrates when applied. With such a configuration, it is possible to increase the amplitude of the stretching vibration in the first direction.

  Furthermore, the vibrating body is preferably a rectangle having sides parallel to the first direction and the second direction.

  In addition, the resonance frequency adjusting method for a vibrator according to the present invention is characterized in that one or both of both ends along the first direction of the elastic plate member in the vibrator are removed. Furthermore, it is preferable that one or both of both ends along the first direction of the elastic plate member are removed in parallel with the second direction.

  According to the present invention, in a piezoelectric vibrator that vibrates in a low-order vibration mode, elliptical motions in opposite directions can be generated with a large driving force at both ends extending from the center without providing a hole.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a front view of a piezoelectric vibrator to which the first embodiment of the present invention is applied. FIG. 2 is a side view of the piezoelectric vibrator. The piezoelectric vibrator 10 includes plate-like piezoelectric elements 20 and 20 and a shim 30 that is a metal plate. The shim 30 is sandwiched between plate-like piezoelectric elements 20 and 20 polarized in the thickness direction.

  The piezoelectric elements 20 and 20 are formed with a first protrusion 21a and a second protrusion 21b that extend from the center of the piezoelectric elements 20 and 20 to both sides along a first direction D1 on the surface. The first protrusion 21a and the second protrusion 21b are formed in a rectangular shape by two sides parallel to the first direction D1 and a side 22 parallel to the second direction D2 perpendicular to the first direction D1. The side portion 22 is located at the forefront along the first direction D1 from the center of the piezoelectric elements 20 and 20.

  The piezoelectric elements 20 and 20 are formed with a third protrusion 21c and a fourth protrusion 21d that extend on both sides along the second direction D2. The third and fourth protrusions 21c and 21d are formed such that the width decreases in a tapered shape as they extend outward along the second direction D2. The piezoelectric elements 20 and 20 are line symmetric with respect to the first direction D1 and the second direction D2. The frequency can be adjusted by adjusting the length and angle of the taper.

  Electrodes are provided on the surfaces of the piezoelectric elements 20 and 20. The electrode is divided into two along the second direction D2, and the first electrode 23a and the second electrode 23b are formed. AC voltages having different phases are applied to the first and second electrodes 23a and 23b.

  The shim 30 includes a first contact portion 31a, a second contact portion 31b, a first support portion 32a, and a second support portion 32b. The 1st contact part 31a and the 2nd contact part 31b are further extended outside along the 1st direction D1 from the 1st protrusion part 21a and the 2nd protrusion part 21b, respectively.

  The piezoelectric elements 20, 20 and the shim 30 are formed so as to be substantially symmetric in the first and second directions D1 and D2, respectively. Accordingly, the piezoelectric vibrator 10 as a whole is substantially symmetric in the first and second directions D1 and D2. According to such a shape, it becomes possible to generate a stable vibration.

  As an example, when the shim 30 is stainless steel and the piezoelectric element 20 is PZT in the piezoelectric vibrator 10 described above, the width from the tip of the first protrusion 21a to the tip of the second protrusion 21b (see E in FIG. 1). , The width from the tip of the third protrusion 21c to the tip of the fourth protrusion 21d (see FIG. 1 reference A), the width of the tip of the first and second protrusions 21a and 21b (see reference B of FIG. 1), third, The widths of the tips of the fourth protrusions 21c and 21d (see reference numeral F in FIG. 1) are formed so as to have a ratio of 8.1: 8: 4: 1.7, respectively, thereby matching the resonance frequencies of the two modes. It is possible to make it.

  FIG. 3 is a view showing a cross section of an ultrasonic motor 50 including the piezoelectric vibrator of the present embodiment. As shown in FIG. 3, the first and second contact portions 31a and 31b are in contact with the rotors 52 and 52, respectively. With such a configuration, the piezoelectric element is prevented from coming into direct contact with the rotors 52 and 52, and the durability of the entire piezoelectric vibrator is improved.

  The first and second support portions 32 a and 32 b are formed in a T shape having an arm portion 33 and a leg portion 34. The leg portion 34 is parallel to the second direction D2, extends outward from the third and fourth projecting portions 21c, 21d, and the arm portion 33 is arranged to be parallel to the first direction D1. A hole is provided in the arm portion 33 in the thickness direction of the piezoelectric vibrator 10. The piezoelectric vibrator 10 is supported by the ultrasonic motor 50 by inserting the male screw into the hole and screwing the male screw into the ultrasonic motor 50 that is a piezoelectric vibrator support body provided with the piezoelectric vibrator. .

  As shown in FIG. 1, a hole 35a (first connection point) provided in the first support part 32a and a hole 35b (second connection point) provided in the second support part 32b are in a second direction D2 to be described later. Is provided at a position that deviates from a straight line that passes through the vibration center C where the bending vibration is the largest and is parallel to the second direction D2.

  The value obtained by dividing the square root of the ratio of the piezoelectric vibrator 10 and the sum of the rigidity of the first and second support portions 32a and 32b in the second direction D2 by 2 × π matches the frequency of the applied AC voltage. Thus, the length of the arm portion 33 is determined.

  By determining the length of the arm portion 33 as described above, the rigidity in the second direction of the first and second support portions 32a and 32b at the frequency of the applied AC voltage becomes sufficiently small, and the piezoelectric vibrator 10 Can be prevented from being damaged by the first and second support portions 32a and 32b.

  FIG. 4 is a block diagram showing a drive circuit for driving the piezoelectric vibrator 10 to which the first embodiment is applied. The drive circuit 40 includes an oscillation unit 41, a phase shift unit L42, a phase shift unit F43, a first amplification unit 44a, a second amplification unit 44b, a first addition unit 45a, and a second addition unit 45b.

  The oscillation unit 41 is connected to the phase shift unit L42 and the phase shift unit F43. The phase shifter L42 is connected to the first amplifier 44a, and the phase shifter F43 is connected to the second amplifier 44b. Both the first addition unit 45a and the second addition unit 45b are connected to the first amplification unit 44a and the second amplification unit 44b. The first adder 45a is connected to the first electrode 23a of the piezoelectric vibrator 10, and the second adder 45b is connected to the second electrode 23b.

  An alternating voltage is generated in the oscillating unit 41 and applied to the phase shift unit L42 and the phase shift unit F43. The phase of the AC voltage generated in the oscillating unit 41 is changed to become a signal for causing the piezoelectric vibrator 10 to expand and contract in the first direction D1 in the phase shift unit L42, and the voltage becomes sin ωt. The phase of the AC voltage generated in the oscillating unit 41 is changed to be a signal for bending and vibrating the piezoelectric vibrator in the second direction D2 in the phase shift unit F43, and the voltage becomes cos ωt.

  The voltages sinωt and cosωt at the output terminals of the phase shift unit L42 and the phase shift unit F43 are amplified by predetermined amplification factors A and B by the first amplification unit 44a and the second amplification unit 44b, and become Asinωt and Bcosωt. . The first amplifying unit 44a and the second amplifying unit 44b are respectively connected to the amplitude control unit 46, and the amplification factors A and B are set by the amplitude control unit 46.

  The first adder 45a adds the voltage Asinωt at the output terminal of the first amplifier 44a, subtracts the voltage Bcosωt at the output terminal of the second amplifier 44b, and applies the voltage of Asinωt−Bcosωt to the first electrode 23a. To do.

  The second adder 45b adds the voltage Asinωt at the output terminal of the first amplifier 44a, adds the voltage Bcosωt at the output terminal of the second amplifier 44b, and applies the voltage Asinωt + Bcosωt to the second electrode 23b.

  The vibration of the piezoelectric vibrator 10 due to the voltage applied by the circuit configuration as described above will be described with reference to FIGS. 1 and 5 to 8.

  FIG. 1 is a view showing the appearance of the piezoelectric vibrator in a state where no voltage is applied to the first electrode 23a and the second electrode 23b. In a state where no voltage is applied, the piezoelectric element does not deform and remains stationary. In the piezoelectric vibrator 10, a portion to which a positive voltage is applied expands, and a portion to which a negative voltage is applied contracts. For example, when a positive voltage is applied to the first electrode 23a, the piezoelectric element in the first electrode 23a expands, and when a negative voltage is applied to the second electrode 23b, the piezoelectric element in the second electrode 23b contracts.

  FIG. 5 is a diagram showing a state of the piezoelectric vibrator 10 when the phase of the applied voltage is ωt = 0. At this time, a negative voltage −B is applied to the first electrode 23a, and a positive voltage + B is applied to the second electrode 23b. Accordingly, the piezoelectric element in the first electrode 23a contracts and the piezoelectric element in the second electrode 23b expands. The piezoelectric vibrator 10 bends in the second direction D2 until the first state in which the piezoelectric element contracts in the first electrode 23a and the piezoelectric element expands in the second electrode 23b is maximized. Since the bending primary mode vibration is free at both ends, the center C of the piezoelectric vibrator 10 is displaced in the opposite direction along the first and second contact portions 31a and 31b and the second direction D2.

  FIG. 6 is a diagram illustrating the state of the piezoelectric vibrator 10 when the phase of the applied voltage is ωt = π / 2. At this time, a positive voltage + A is applied to both electrodes 23a and 23b. Therefore, the expansion and contraction of the piezoelectric element in the first electrode 23a and the piezoelectric element in the second electrode 23b expands along the first direction D1 from the stationary state. The piezoelectric vibrator 10 expands in the first direction D1 until the second state where the expansion of the piezoelectric elements 20 and 20 is maximized.

  At this time, the piezoelectric vibrator 10 extends in the first direction D1, but most of the third and fourth projecting portions 21c and 21d are displaced inward in the second direction. This vibration mode is a mode corresponding to the contour sliding mode in the square plate, and is the lowest order mode in which the length between the first and second contact portions 31a and 31b expands and contracts.

  FIG. 7 is a diagram showing a state of the piezoelectric vibrator 10 when the phase of the applied voltage is ωt = π. At this time, a positive voltage + B is applied to the first electrode 23a, while a negative voltage -B is applied to the second electrode 23b. Accordingly, the piezoelectric element in the second electrode 23b contracts and the piezoelectric element in the first electrode 23a expands. The piezoelectric vibrator 10 bends in the second direction D2 until the third state in which the contraction of the piezoelectric element in the second electrode 23b and the expansion of the piezoelectric element in the first electrode 23a are maximized. Since the bending primary mode vibration is free at both ends, the center C of the piezoelectric vibrator 10 is displaced in the opposite direction along the first and second contact portions 31a and 31b and the second direction D2.

  FIG. 8 is a diagram illustrating a state of the piezoelectric vibrator 10 when the phase of the applied voltage is ωt = (3/2) π. At this time, a negative voltage −A is applied to both electrodes 23a and 23b. Therefore, the expansion and contraction of the piezoelectric element in the first electrode 23a and the piezoelectric element in the second electrode 23b is reduced from the stationary state in the first direction D1. The piezoelectric vibrator 10 contracts in the first direction D1 until the fourth state where the contraction of the piezoelectric elements 20 and 20 is maximized. At this time, the piezoelectric vibrator 10 contracts in the first direction D1, but most of the third and fourth projecting portions 21c and 21d are displaced outward in the second direction D2.

  The piezoelectric vibrator 10 changes from the fourth state to the first state, and thereafter cyclically deforms in a second state, a third state, a fourth state, a first state, and so on. When the outer shape of the piezoelectric vibrator 10 changes in this way, an arbitrary point on the side portion 22 performs an elliptical motion.

  According to the configuration as described above, it is possible to generate vibrations in the expansion / contraction primary mode and the bending primary mode in the first direction D1 and the second direction D2, respectively, and the side portion 22 of the first protrusion portion. In addition, it is possible to generate an elliptical motion having a large driving force in opposite directions and in the bending direction at the side portion 22 of the second projecting portion.

  FIG. 9 shows a second embodiment of the present invention. This embodiment is different from the first embodiment in the arrangement of electrodes provided on the surface of the piezoelectric element and the voltage applied to each electrode. In the present embodiment, the electrode is divided into three along the second direction D2, and the first electrode 23a and the second electrode 23b are formed on both sides, and the third electrode 23c is formed in the middle.

  AC voltages having different phases are applied to the first to third electrodes 23a, 23b, and 23c. As will be described later, the polarities of the AC voltages applied to the first and second electrodes 23a and 23b are reversed, and the third electrode 23c is applied to one of the first and second electrodes 23a and 23b. The AC voltage is 90 ° different in phase from the AC voltage applied, and the AC voltage applied is 90 ° different in phase from the AC voltage applied to the other.

  FIG. 10 is a block diagram showing a drive circuit for driving the piezoelectric vibrator 100 to which the second embodiment is applied. The drive circuit 400 includes an oscillation unit 41, a phase shift unit L42, a phase shift unit F43, a first amplification unit 44a, a second amplification unit 44b, a first addition unit 45a, and a second addition unit 45b.

  The oscillating unit 41 is connected to the phase shift unit L42 and the phase shift unit F43. The phase shifter L42 is connected to the first amplifier 44a, and the phase shifter F43 is connected to the second amplifier 44b. The first amplification unit 44a is connected to the third electrode 23c. The second amplification unit 44b is connected to the first addition unit 45a and the second addition unit 45b. The first adder 45a is connected to the first electrode 23a of the piezoelectric vibrator 10, and the second adder 45b is connected to the second electrode 23b.

  An alternating voltage is generated in the oscillating unit 41 and is applied to the phase shift unit L42 and the phase shift unit F43. The phase of the AC voltage generated in the oscillating unit 41 is changed to become a signal for causing the piezoelectric vibrator 10 to expand and contract in the first direction D1 in the phase shift unit L42, and the voltage becomes sin ωt. The phase of the AC voltage generated in the oscillating unit 41 is changed to be a signal for bending and vibrating the piezoelectric vibrator in the second direction D2 in the phase shift unit F43, and the voltage becomes cos ωt.

  The voltages sinωt and cosωt at the output terminals of the phase shift unit L42 and the phase shift unit F43 are amplified by predetermined amplification factors A and B by the first amplification unit 44a and the second amplification unit 44b, and become Asinωt and Bcosωt. . The first amplifying unit 44a and the second amplifying unit 44b are respectively connected to the amplitude control unit 46, and the amplification factors A and B are set by the amplitude control unit 46.

  The voltage Asinωt amplified in the first amplifying unit 44a is applied to the third electrode 23c. In the first adder 45a, the voltage Bcosωt at the output terminal of the first amplifier 44a is subtracted, and a voltage of −Bcosωt is applied to the first electrode 23a. In the second adder 45b, the voltage Bcosωt at the output terminal of the second amplifier 44b is added, and a voltage of + Bcosωt is applied to the second electrode 23b.

  In the piezoelectric vibrator to which the second embodiment is applied as described above, bending vibration along the second direction D2 is generated by expansion and contraction of the piezoelectric elements in the first electrode 23a and the second electrode 23b, and the third electrode The expansion and contraction vibration along the first direction D1 can be generated by expansion and contraction of the piezoelectric element in 23c, and an elliptical motion can be performed on the side portion by combining these vibrations.

  FIG. 11 shows a vibrator to which the third embodiment of the present invention is applied. This embodiment is different from the first embodiment in the shape of a piezoelectric element and a shim constituting a piezoelectric vibrator.

  The shim 300 (elastic plate member) is formed with a first protrusion 36a and a second protrusion 36b extending from the center of the shim 300 to both sides along the first direction D1 on the surface. The first protrusion 36a and the second protrusion 36b are formed in a rectangular shape by two sides parallel to the first direction D1 and a side parallel to the second direction D2 perpendicular to the first direction D1.

  The shim 300 is formed with a third projecting portion 36c and a fourth projecting portion 36d that extend on both sides along the second direction D2. The third and fourth protrusions 36c and 36d are formed such that the width decreases in a tapered shape as they extend outward along the second direction D2. The shim 300 is line symmetric with respect to the first direction D1 and the second direction D2. The frequency can be adjusted by adjusting the length and angle of the taper.

  The first and second contact portions 31a and 31b formed on the shim 300 are further extended outward along the first direction D1 from the first and second projecting portions 36a and 36b. The configurations and functions of the first and second support portions 32a and 32b formed in the shim 300 are the same as those in the first embodiment.

  The piezoelectric elements 200 and 200 (vibrating bodies) are formed in a rectangular shape having two sides along the first direction D1 and two sides along the second direction D2 as outer edges. The piezoelectric elements 200 and 200 are formed so that the length in the first direction D1 is longer than the width in the second direction D2. The configuration in which the first and second electrodes 230a and 230b are provided on the surfaces of the piezoelectric elements 200 and 200 is the same as that in the first embodiment.

  Also in the piezoelectric vibrator 101 of the present embodiment as described above, the vibration of the expansion / contraction primary mode and the bending primary mode can be generated in the first direction D1 and the second direction D2 using the drive circuit 40, respectively. It is possible, and it is possible to generate an elliptical motion with a large driving force in the bending direction in the first protruding portion 36a and the second protruding portion 36b in opposite directions.

  The resonance frequency of the stretching vibration in the first direction D1 and the resonance frequency in the second direction D2 of the piezoelectric vibrator are determined by the shape of the entire piezoelectric vibrator, and not only the shape of the piezoelectric element but also the shape of the shim described above. By forming in this way, a vibrator capable of vibrating according to the purpose can be obtained.

  In this embodiment, the amplitude of the stretching vibration in the first direction D1 can be increased as compared with the piezoelectric vibrators of the first and second embodiments. Like the third and fourth projecting portions 21c and 21d of the piezoelectric elements used in the first and second embodiments, there is no projecting portion extending from the center to both sides along the second direction, and it expands and contracts in the first direction D1. It is because it becomes easy to do.

  In the present embodiment, the shape of the piezoelectric elements 200 and 200 is rectangular, but the shape extends in the first direction D1, and the length in the first direction D1 is longer than the width in the second direction D2. For example, it may be oval.

  In the first to third embodiments, the electrode is divided into two or three along the second direction D2, but is divided into two or more along the second direction D2, that is, second. A similar effect can be obtained if a plurality of electrodes are arranged along the direction D2. Moreover, when dividing | segmenting into 3 or more, the structure in which an electrode is further provided between the 1st, 2nd electrode is preferable. That is, AC voltages having different phases are input to the two outermost electrodes along the second direction D2.

  Further, in the first to third embodiments, the metal shim is used, but if it is a plate member having elasticity, the same effect as that of the present embodiment is produced.

  In the first and second embodiments, the piezoelectric vibrator has a shape in which a rectangular protrusion is provided on the outer side from two opposite sides of the octagon. However, as shown in FIG. 12, the piezoelectric element 201 formed in an octagon. Therefore, the resonance frequency of the primary mode of expansion and contraction and the primary mode of bending can be matched without opening a hole. Alternatively, the same effect can be obtained even when the shim in the third embodiment is formed in an octagon like the piezoelectric element 201.

  Furthermore, if the vibrator has a shape having protrusions on both sides along the first and second directions D1 and D2 from the center, and a side portion is provided at the tip of at least one pair of opposite protrusions, The effect is obtained.

  In the first to third embodiments, the piezoelectric element is used to vibrate the vibrator. However, an element (vibrating body) that vibrates by applying an AC voltage such as an electrostrictive element may be used. The effects described above can be obtained.

  Next, a modification of the shim in the first to third embodiments is shown in FIG. In this modification, the shim 301 (elastic plate member) having elasticity is formed in a plate shape. The plate-like surface of the shim 301 and the plate-like surface of the piezoelectric element 20 are combined.

  The shim 301 is formed to extend outwardly beyond the first and second projecting portions 21 a and 21 b along the first direction D <b> 1 in a state where the shim 301 is coupled to the piezoelectric elements 20 and 20. Further, the shim 301 is formed such that both ends 37 and 37 along the first direction D1 are parallel to the second direction D2. In the shim 301, the first and second contact portions 31a and 31b are formed so as to protrude outward beyond both ends 37 and 37 along the first direction D1 of the shim 301. The configurations and functions of the piezoelectric elements 20 and 20 are the same as those in the first embodiment.

  As described above, the resonance frequency in the first direction D1 and the resonance frequency in the second direction D2 of the vibrator 102 to which the shim 301 is applied are equal to one or both of the both ends 37, 37 along the first direction D1 of the shim 301. It changes at a different rate depending on the size to be deleted. That is, by appropriately removing one or both of the both ends 37 and 37 along the first direction D1 of the shim 301 with respect to the formed vibrator, the resonance frequencies of the first and second directions D1 and D2 are respectively removed. Can be matched.

  In the vibrator after formation, it is difficult to change the size of the piezoelectric element, and when the resonance frequency in the first and second directions D1 and D2 shifts due to the formation error of the piezoelectric element, fine adjustment to match the resonance frequency is difficult. However, according to the vibrator using the shim formed of a member that can be cut, fine adjustment for matching the resonance frequency is facilitated.

  In addition, it is desirable to measure in advance the amount of change in the resonance frequency of the vibrator 102 in the first and second directions D1 and D2 with respect to the cutting amount parallel to the second direction D2 of both ends 37 and 37. By removing both ends 37 and 37 of the shim 301 in parallel with the second direction D2 based on the measured variation with respect to the resonance frequency shift in the first and second directions D1 and D2 of the formed vibrator. Fine adjustment becomes easier.

  In this modification, the shim 301 extends on both sides along the first direction D1, but may have a configuration extending on both sides along the second direction D2. However, the configuration extending along the second direction D2 is less sensitive to the change in the resonance frequency with respect to the cutting amount at both ends than the configuration extending along the first direction D1. Therefore, when the formation accuracy of the piezoelectric element is relatively high and the fine adjustment of the resonance frequency is small, a sufficient effect can be obtained even with the configuration extending in the second direction D2.

1 is a front view of a piezoelectric vibrator to which a first embodiment of the present invention is applied. 1 is a side view of a piezoelectric vibrator to which a first embodiment is applied. It is sectional drawing of the ultrasonic motor provided with the piezoelectric material vibrator to which 1st Embodiment is applied. It is a block diagram of the drive circuit connected to the electrode of the piezoelectric vibrator to which the first embodiment is applied. It is a figure which shows the bending state to the 2nd direction of a piezoelectric material vibrator. It is a figure which shows the expansion | extension state to the 1st direction of a piezoelectric vibrator. It is a figure which shows the bending state to the 2nd direction of a piezoelectric material vibrator. It is a figure which shows the contraction state to the 1st direction of a piezoelectric vibrator. It is a front view of the piezoelectric vibrator to which the 2nd Embodiment of this invention is applied. It is a block diagram of a drive circuit connected to an electrode of a piezoelectric vibrator to which a second embodiment is applied. It is a front view of the piezoelectric vibrator to which the third embodiment of the present invention is applied. It is a figure which shows the modification of the external shape of the piezoelectric material vibrator to which the 1st, 2nd embodiment is applied. It is a figure which shows the modification of a shim.

Explanation of symbols

10, 100, 101, 102 Piezoelectric vibrators 20, 200, 201 Piezoelectric elements 21a-21d First to fourth protrusions 22 Sides 23a, 230a First electrodes 23b, 230b Second electrodes 23c Third electrodes 30, 300 , 301 Shims 31a, 31b First and second contact portions 32a, 32b First and second support portions 36a, 36b First and second protrusions 40, 400 Drive circuit 41 Oscillating portion 42 Phase shift portion L
43 Phase shift part F
44a, 44b First and second amplifiers 45a, 45b First and second adders C Center of vibration D1 First direction D2 Second direction

Claims (15)

First and second protrusions extending from the center of the vibrator to both sides along a first direction and having sides parallel to a second direction perpendicular to the first direction at the forefront;
Third and fourth protrusions extending from the center to both sides along the second direction;
First and second electrodes arranged along the second direction,
Vibrating by applying alternating voltages having different phases to the first and second electrodes, respectively.   The vibrator according to claim 1, wherein an electrode is further provided between the first and second electrodes.   2. The vibrator according to claim 1, wherein the width decreases as the third and fourth protrusions extend from the center along the second direction.   The vibrator according to claim 1, wherein the first protrusion is formed by the side and two sides parallel to the first direction.   The distance between the tip of the third protrusion and the tip of the fourth protrusion is shorter than the distance between the tip of the first protrusion and the tip of the second protrusion. The vibrator according to claim 1.   A third electrode is provided between the first and second electrodes, the phase of the AC voltage applied to one of the first and second electrodes to the third electrode is 90 °, and the other is applied to the other. The vibrator according to claim 1, wherein an AC voltage having a phase different from that of the AC voltage by −90 ° is applied.   The vibrator according to claim 1, wherein the vibrator is substantially symmetrical with respect to the first direction and the second direction. Each of the third and fourth protrusions has first and second support members for supporting the vibrator on a vibrator support provided with the vibrator,
In the first support member, a straight line passing through a vibration center where a first connection point connecting the vibrator and the first support member is a point where the vibration in the second direction of the vibrator is the largest. And provided at a position deviating from a straight line parallel to the second direction,
The second support member is provided with a second connection point for connecting the vibrator and the second support member at a position deviating from a straight line passing through the vibration center and parallel to the second direction. The vibrator according to claim 1. A plate-like vibrating body having the first and second protrusions and the first and second electrodes, and vibrating by applying an alternating voltage;
2. The vibrator according to claim 1, further comprising: an elastic plate member that is in close contact with the vibrating body and has an adjustment portion that extends outward from the first and second projecting portions along the first direction.   The vibrator according to claim 9, wherein both ends of the elastic plate member along the first direction are formed in parallel with the second direction.   The vibrator according to claim 10, wherein the elastic plate member is provided with a contact portion that protrudes outward from both ends along the first direction. An elastic plate member having the first to fourth protrusions;
The length of the first direction is longer than the width of the second direction, is in close contact with the elastic plate member, has the first and second electrodes, and vibrates by applying an AC voltage. The vibrator according to claim 1, further comprising: a vibrating body.   The vibrator according to claim 12, wherein the vibrating body is a rectangle having sides parallel to the first direction and the second direction.   11. The method for adjusting a resonance frequency of a vibrator according to claim 10, wherein one or both of both ends along the first direction of the elastic plate member are removed. 15. The resonance frequency adjustment of the vibrator according to claim 14, wherein one or both of both ends of the elastic plate member along the first direction are removed in parallel with the second direction. Method.

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