JP2016178711A - Piezoelectric drive device, robot, and method of driving the robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessively strong braking from being applied to a driven body.SOLUTION: A piezoelectric drive device comprises: a piezoelectric drive part for driving a driven body; and a drive circuit for driving the piezoelectric drive part. The piezoelectric drive part comprises: a piezoelectric vibrator having a first piezoelectric element and a second piezoelectric element; and a contact part contacted with the driven body. In the piezoelectric vibrator, at least a part of the first piezoelectric element is arranged at one side with respect to a center line along a longitudinal direction of the piezoelectric vibrator, and at least a part of the second piezoelectric element is arranged at the other side with respect to the center line. The drive circuit, at least at one of a stop or a braking of the driven body, supplies to the first piezoelectric element a first drive signal whose voltage is periodically changed in a predetermined cycle, and supplies to the second piezoelectric element a second drive signal whose voltage is periodically changed in a predetermined cycle having a different phase from the first drive signal, and thereby, makes the contact part vibrate in a width direction crossing the longitudinal direction.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a piezoelectric driving device, a robot, and a driving method thereof.

  As a piezoelectric actuator (piezoelectric driving device) that drives a driven body by vibrating a vibrating body by a piezoelectric element, for example, a piezoelectric driving device described in Patent Document 1 is known. In this piezoelectric driving device, by applying an alternating voltage to the piezoelectric element, stretching vibration that expands and contracts the vibrating body in the length direction (also referred to as “longitudinal vibration”), and bending vibration that causes the vibrating body to bend in the width direction, The abutting portion provided on the vibrating body is moved so as to draw a substantially elliptical trajectory, and the abutting portion is brought into contact with the driven body according to the elliptical motion (also referred to as “elliptical vibration”) to be driven. Driving the body.

JP2013-13218A

  When the application of the AC voltage to the piezoelectric element of the piezoelectric driving device is stopped and the driving of the driven body is stopped, the vibration of the piezoelectric driving device (vibrating body) stops. At this time, excessive braking force acts on the driven body due to a large frictional force acting between the contact portion and the driven body, and abnormal noise is generated from the apparatus using the piezoelectric driving apparatus, or the piezoelectric driving apparatus is used. In some cases, the device could not operate smoothly. In addition, slippage may occur between the contact portion and the driven body due to a large frictional force, and the contact portion or the driven body may be deteriorated due to friction, resulting in a decrease in durability. Further, in a state where the drive of the driven body is stopped and the movement of the driven body is stopped, it is difficult to manually move the driven body.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(1) According to one aspect of the present invention, a piezoelectric driving device is provided. The piezoelectric drive device includes a piezoelectric drive unit that drives a driven body; and a drive circuit that drives the piezoelectric drive unit. The piezoelectric driving unit includes a piezoelectric vibrating body having a first piezoelectric element and a second piezoelectric element; and a contact part that contacts the driven body. In the piezoelectric vibrator, at least a part of the first piezoelectric element is disposed on one side with respect to a center line along the longitudinal direction of the piezoelectric vibrator; at least of the second piezoelectric element. A part is arranged on the other side of the one side with respect to the center line. The drive circuit supplies a first drive signal whose voltage periodically changes at a predetermined cycle to the first piezoelectric element when the driven body is stopped or braked. The second piezoelectric element is supplied with a second drive signal whose voltage periodically changes in the predetermined cycle with a phase different from that of the first drive signal, thereby moving the contact portion in the longitudinal direction. Vibrate along the intersecting width direction.
According to this aspect, since the contact portion vibrates along the width direction, when the driven body is braked, the frictional force acting between the driven body and the contact portion is reduced, and an excessive braking force is applied to the driven body. Can be prevented from working. As a result, braking of the device using the piezoelectric drive device can be performed smoothly, and generation of abnormal noise from the device using the piezoelectric drive device can be suppressed. Further, when the driven body is stopped, the driven body can be manually moved.

(2) In the piezoelectric driving device according to the aspect described above, the piezoelectric vibrating body may be configured such that the first piezoelectric element and the second piezoelectric element are arranged symmetrically with respect to the center line.
According to this aspect, at the time of braking of the driven body, the frictional force acting between the driven body and the contact portion can be effectively reduced, and an excessive braking force can be prevented from acting on the driven body. . Further, when the driven body is stopped, the driven body can be manually moved.

(3) In the piezoelectric driving device according to the above aspect, the piezoelectric vibrating body includes the first piezoelectric element and the second piezoelectric element arranged along the longitudinal direction on one side of the one side. On the other hand, the second piezoelectric element and the first piezoelectric element may be arranged along the longitudinal direction.
According to this aspect, at the time of braking of the driven body, the frictional force acting between the driven body and the contact portion is more effectively reduced, and it is possible to suppress the excessive braking force from acting on the driven body. it can. Further, when the driven body is stopped, the driven body can be manually moved.

(4) In the piezoelectric drive device according to the above aspect, the drive circuit changes at least one of a voltage amplitude of the first drive signal, a voltage amplitude of the second drive signal, and a phase difference. It is good also as including the adjustment circuit to make.
According to this aspect, for example, by adjusting the phase difference, amplitude, DC offset, and the like between the first drive signal and the second drive signal, the characteristic difference between the first piezoelectric element and the second piezoelectric element can be reduced. Compensation, compensation for displacement of the assembly position of the piezoelectric drive unit, and the like can be performed. Moreover, the neutral point of vibration can be adjusted.

(5) In the piezoelectric driving device according to the above aspect, the piezoelectric vibrating body further includes a third piezoelectric element disposed along the center line; the driving circuit is at least one of the stop state and the brake state A) supplying the first drive signal to the first piezoelectric element and supplying the second drive signal to the second piezoelectric element, thereby moving the contact portion in the width direction. B) bending vibration to be oscillated along, and b) supplying a third drive signal whose voltage periodically changes at the predetermined period to the third piezoelectric element, thereby causing the contact portion to extend along the longitudinal direction. It is also possible to execute either one of the longitudinal vibration to vibrate in a switchable manner.
According to this aspect, when the driven body is stopped or braked, the bending vibration and the longitudinal vibration can be appropriately switched and operated.

(6) In the piezoelectric drive device of the above aspect, the drive circuit supplies the first drive signal to the first piezoelectric element and at least one of the second drive at least one of the stop time and the brake time. Bending vibration that causes the contact portion to vibrate along the width direction by supplying the second driving signal to the piezoelectric element; and b) applying the predetermined force to the first piezoelectric element and the second piezoelectric element. By supplying a third drive signal whose voltage periodically changes at a period of, it is possible to switch any one of the longitudinal vibration that vibrates the contact portion along the longitudinal direction. Also good.
Also in this form, when the driven body is stopped or braked, the bending vibration and the longitudinal vibration can be appropriately switched and operated.

(7) In the piezoelectric driving device according to the aspect described above, the contact portion is provided so as to be able to contact the driven body disposed along the longitudinal direction of the piezoelectric vibrating body; A vibration in which the driven body and the contact portion repeat contact and non-contact along the longitudinal direction; the first bending vibration and the second bending vibration are each along a direction intersecting the longitudinal direction. The driven body and the contact portion may be vibrations that repeat sliding and non-sliding.
According to this aspect, it is possible to suppress an excessive braking force from acting on the driven body disposed along the longitudinal direction of the piezoelectric vibrating body. Further, when the driven body is stopped, the driven body can be manually moved.

(8) In the piezoelectric drive device according to the above aspect, the piezoelectric vibrating body may be provided on a diaphragm.

  The present invention can be realized in various forms. For example, in addition to a piezoelectric driving device, a driving method of the piezoelectric driving device, a manufacturing method of the piezoelectric driving device, a robot equipped with the piezoelectric driving device, and a piezoelectric driving device. It can be realized in various forms such as a driving method of a robot to be mounted, an electronic component conveying device, a liquid feeding pump, a medication pump, and the like.

It is a block diagram which shows schematic structure of the piezoelectric drive device as 1st Embodiment. It is a schematic block diagram of a piezoelectric drive part. It is a top view of a diaphragm. It is explanatory drawing which shows the electrical connection state of a piezoelectric drive part and a drive circuit. It is explanatory drawing which shows the example of a waveform of the 1st and 2nd bending drive signal and a longitudinal drive signal. It is explanatory drawing which shows the example of the waveform of alternating current drive voltage SAC. It is explanatory drawing which shows typically the longitudinal vibration operation | movement of a piezoelectric drive part. It is explanatory drawing which shows typically the bending vibration operation | movement of a piezoelectric drive part. It is explanatory drawing which shows typically the elliptical vibration operation | movement of a piezoelectric drive part. It is explanatory drawing shown about the vibration direction of the bending vibration of FIG. It is explanatory drawing which shows schematic structure of the piezoelectric drive part and drive circuit in the piezoelectric drive device of 2nd Embodiment. It is explanatory drawing shown about the elliptical vibration operation | movement of a piezoelectric drive part. It is explanatory drawing shown about the bending vibration operation | movement of a piezoelectric drive part. It is explanatory drawing shown about the longitudinal vibration operation | movement of a piezoelectric drive part. It is sectional drawing of the piezoelectric drive part as other embodiment of this invention. It is a plane schematic diagram of the piezoelectric drive part as other embodiment of this invention. It is explanatory drawing which shows an example of the robot using a piezoelectric drive device. It is explanatory drawing of the wrist part of a robot. It is explanatory drawing which shows an example of the liquid feeding pump using a piezoelectric drive device.

A. Piezoelectric drive device of the first embodiment:
A1. Piezoelectric drive configuration:
FIG. 1 is a block diagram showing a schematic configuration of a piezoelectric driving apparatus 1000 as the first embodiment. The piezoelectric drive device 1000 includes a piezoelectric drive unit 10 that drives a driven body (rotor in this example) 50 and a drive circuit 300 that drives the piezoelectric drive unit 10.

  FIG. 2 is a schematic configuration diagram of the piezoelectric driving unit 10. 2A is a plan view of the piezoelectric drive unit 10, and FIG. 2B is a cross-sectional view taken along the line BB. The piezoelectric drive unit 10 includes a vibration plate 200 and two piezoelectric vibration members 100 disposed on both surfaces (first surface 211 and second surface 212) of the vibration plate 200, respectively. The piezoelectric vibrating body 100 includes a substrate 120, a first electrode 130 formed on the substrate 120, a piezoelectric body 140 formed on the first electrode 130, and a second electrode formed on the piezoelectric body 140. An electrode 150. The first electrode 130 and the second electrode 150 sandwich the piezoelectric body 140. The two piezoelectric vibrators 100 are arranged symmetrically about the diaphragm 200. Since the two piezoelectric vibrators 100 have the same configuration, the configuration of the piezoelectric vibrator 100 on the upper side of the diaphragm 200 will be described below unless otherwise specified.

The substrate 120 of the piezoelectric vibrating body 100 is used as a substrate for forming the first electrode 130, the piezoelectric body 140, and the second electrode 150 by a film forming process. The substrate 120 also has a function as a diaphragm that performs mechanical vibration. The substrate 120 can be formed of, for example, Si, Al ₂ O ₃ , ZrO ₂ or the like. As the Si substrate 120, for example, a Si wafer for semiconductor manufacturing can be used. In this embodiment, the planar shape of the substrate 120 is a rectangle. The thickness of the substrate 120 is preferably in the range of 10 μm to 100 μm, for example. If the thickness of the substrate 120 is 10 μm or more, the substrate 120 can be handled relatively easily during the film forming process on the substrate 120. If the thickness of the substrate 120 is 100 μm or less, the substrate 120 can be easily vibrated according to the expansion and contraction of the piezoelectric body 140 formed of a thin film.

  The first electrode 130 is formed as one continuous conductor layer formed on the substrate 120. On the other hand, as shown in FIG. 2A, the second electrode 150 is divided into five conductor layers 150a to 150e (also referred to as “second electrodes 150a to 150e”). The second electrode 150e at the center is formed in a rectangular shape covering almost the entire length of the substrate 120 at the center in the width direction of the substrate 120. The other four second electrodes 150 a, 150 b, 150 c, and 150 d have the same planar shape and are formed at the four corner positions of the substrate 120. In the example of FIG. 2, both the first electrode 130 and the second electrode 150 have a rectangular planar shape. The first electrode 130 and the second electrode 150 are thin films formed by sputtering, for example. As a material of the first electrode 130 and the second electrode 150, for example, any material having high conductivity such as Al (aluminum), Ni (nickel), Au (gold), Pt (platinum), Ir (iridium) or the like is used. Is available. Instead of the first electrode 130 being one continuous conductor layer, the first electrode 130 may be divided into five conductor layers having substantially the same planar shape as the second electrodes 150a to 150e. In addition, wiring (or wiring layer and insulating layer) for electrical connection between the second electrodes 150a to 150e, and electrical connection between the first electrode 130 and the second electrodes 150a to 150e and the drive circuit The wiring for the purpose (or the wiring layer and the insulating layer) is not shown in FIG.

  The piezoelectric body 140 is formed as five piezoelectric layers having substantially the same planar shape as the second electrodes 150a to 150e. Alternatively, the piezoelectric body 140 may be formed as one continuous piezoelectric layer having substantially the same planar shape as the first electrode 130. Five piezoelectric elements 110a to 110e (FIG. 2A) are configured by a laminated structure of the first electrode 130, the piezoelectric body 140, and the second electrodes 150a to 150e. Of the five piezoelectric elements 110a to 110e, four piezoelectric elements 110a to 110d are a pair of piezoelectric elements 110a and 110d at a first diagonal, and a pair of piezoelectric elements 110b and 110c at a second diagonal. These are symmetric with respect to the center line CX along the longitudinal direction of the piezoelectric vibrating body 100. The remaining piezoelectric element 110e is sandwiched between the pair of piezoelectric elements 110a and 110d and the other pair of piezoelectric elements 110b and 110c, and is at the center position in the width direction of the piezoelectric vibrating body 100 along the center line CX. Hereinafter, the pair of piezoelectric elements 110a and 110d is also referred to as “first piezoelectric elements 110a and 110d”, and the other pair of piezoelectric elements 110b and 110c is also referred to as “second piezoelectric elements 110b and 110c”. The central piezoelectric element 110e is also referred to as “third piezoelectric element 110e”.

The piezoelectric body 140 is a thin film formed by, for example, a sol-gel method or a sputtering method. As a material of the piezoelectric body 140, any material exhibiting a piezoelectric effect such as ceramics having an ABO ₃ type perovskite structure can be used. Examples of ceramics having an ABO ₃ type perovskite structure include lead zirconate titanate (PZT), barium titanate, lead titanate, potassium niobate, lithium niobate, lithium tantalate, sodium tungstate, zinc oxide, titanium Barium strontium acid (BST), strontium bismuth tantalate (SBT), lead metaniobate, lead zinc niobate, lead scandium niobate, or the like can be used. It is also possible to use a material exhibiting a piezoelectric effect other than ceramic, such as polyvinylidene fluoride and quartz. The thickness of the piezoelectric body 140 is preferably in the range of, for example, 50 nm (0.05 μm) to 20 μm. A thin film of the piezoelectric body 140 having a thickness in this range can be easily formed using a film forming process. If the thickness of the piezoelectric body 140 is 0.05 μm or more, a sufficiently large force can be generated according to the expansion and contraction of the piezoelectric body 140. Moreover, if the thickness of the piezoelectric body 140 is 20 μm or less, the piezoelectric vibrating body 100 (piezoelectric drive unit 10) can be sufficiently downsized.

  FIG. 3 is a plan view of the diaphragm 200. The diaphragm 200 has a rectangular-shaped vibrating body portion 210 and three connecting portions 220 that extend from the left and right long sides of the vibrating body portion 210, respectively. Two attachment portions 230 are connected to each other. In FIG. 2, the vibrating body portion 210 is hatched for convenience of illustration. The attaching part 230 is used for attaching the piezoelectric driving part 10 to another member with a screw 240. The diaphragm 200 is formed of a material such as silicon, silicon compound, stainless steel, aluminum, aluminum alloy, titanium, titanium alloy, copper, copper alloy, iron-nickel alloy or the like, metal oxide, or diamond. It is possible.

  The piezoelectric vibrating body 100 (FIG. 2) is bonded to the upper surface (first surface) and the lower surface (second surface) of the vibrating body portion 210 using an adhesive. The ratio of the length L to the width W of the vibrating body part 210 is preferably L: W = about 7: 2. This ratio is a preferable value for performing ultrasonic vibration (described later) in which the vibrating body portion 210 bends left and right along the plane. The length L of the vibrating body portion 210 can be set in a range of 0.1 mm to 30 mm, for example, and the width W can be set in a range of 0.05 mm to 8 mm, for example. In addition, in order for the vibrating body part 210 to perform ultrasonic vibration, the length L is preferably set to 50 mm or less. The thickness of the vibrating body part 210 (thickness of the vibration plate 200) can be in the range of 20 μm to 700 μm, for example. If the thickness of the vibrating body portion 210 is 20 μm or more, the vibrating body portion 210 has sufficient rigidity to support the piezoelectric vibrating body 100. Further, if the thickness of the vibrating body portion 210 is 700 μm or less, a sufficiently large deformation can be generated according to the deformation of the piezoelectric vibrating body 100.

On one short side of the diaphragm 200, a protrusion 20 (also referred to as “contact portion”, “contact portion”, or “action portion”) is provided. The protrusion 20 is a member that is in contact with the driven body and applies a force to the driven body. The protrusion 20 is preferably formed of a durable material such as ceramics (for example, Si, SiC, Al ₂ O ₃ , Zr0 ₂ ).

  FIG. 4 is an explanatory diagram showing an electrical connection state between the piezoelectric drive unit 10 and the drive circuit 300. Among the five second electrodes 150 a to 150 e of the piezoelectric driving unit 10, the second electrodes 150 a and 150 d of the pair of first piezoelectric elements 110 a and 110 d at the first diagonal are electrically connected to each other via the wiring 151. The second electrodes 150b and 150c of the pair of second piezoelectric elements 110b and 110c of the other second diagonal are also electrically connected to each other via the wiring 152. These wirings 151 and 152 may be formed by a film forming process, or may be realized by wire-like wiring. The three second electrodes 150b, 150e, and 150d on the right side of FIG. 4 and the first electrode 130 (FIG. 2) are electrically connected to the drive circuit 300 via wirings 310, 312, 314, and 320. . Note that the wirings (or wiring layers and insulating layers) constituting the wirings 151, 152, 310, 312, 314, and 320 shown in FIG. 4 are not shown in FIG.

  The piezoelectric drive circuit 300 includes an AC drive voltage generation circuit 332, a bending vibration drive circuit 334, a longitudinal vibration drive circuit 336, and a drive selection circuit 338. The AC drive voltage generation circuit 332 generates an AC drive voltage SAC that varies between a plus side and a minus side with respect to the ground potential. The AC drive voltage SAC is preferably a voltage signal having a frequency close to the mechanical resonance frequency of the piezoelectric drive unit 10.

  The drive selection circuit 338 supplies the AC drive voltage SAC to at least one of the bending vibration drive circuit 334 and the longitudinal vibration drive circuit 336 by the first selection circuit SW1 and the second selection circuit SW2. Specifically, when only the bending vibration driving circuit 334 is operated, the first selection circuit SW1 is selected (ON), the second selection circuit SW2 is not selected (OFF), and the bending vibration driving circuit 334 is operated. The AC drive voltage SAC is supplied only to. When only the longitudinal vibration drive circuit 336 is operated, the first selection circuit SW1 is not selected (OFF), the second selection circuit SW2 is selected (ON), and the AC drive voltage is applied only to the longitudinal vibration drive circuit 336. Supply SAC. When the bending vibration driving circuit 334 and the longitudinal vibration driving circuit 336 are operated, the first and second selection circuits SW1 and SW2 are selected (ON), and the AC driving voltage SAC is supplied to both the driving circuits 334 and 336. .

  The bending vibration drive circuit 334 generates two bending drive signals SBa and SBb of an AC voltage or a pulsating voltage based on the AC drive voltage SAC. The bending vibration driving circuit 334 supplies the first bending driving signal SBa to the second electrodes 150a and 150d of the pair of first piezoelectric elements 110a and 110d via the wiring 314, and the second bending driving signal SBb. The second electrodes 150b and 150c of the pair of second piezoelectric elements 110b and 110c are supplied via a wiring 310. Note that the drive circuit 300 supplies a voltage having the same potential as the ground potential to the first electrode 130 via the wiring 320 as the reference voltage signal SC. Here, the pulsating voltage means a voltage obtained by adding a DC offset to an AC voltage, and the direction of the voltage (electric field) is one direction from one electrode to the other electrode.

  The longitudinal vibration drive circuit 336 generates an alternating current or pulsating longitudinal drive signal SSV based on the alternating current drive voltage SAC, and supplies the vertical drive signal SSV to the second electrode 150e of the third piezoelectric element 110e at the center via the wiring 312.

  FIG. 5 is an explanatory diagram showing waveform examples of the first and second bending drive signals SBa and SBb and the vertical drive signal SSV. The first and second bending drive signals SBa and SBb and the longitudinal drive vibration SSV periodically change at a predetermined cycle corresponding to the frequency of the AC drive voltage SAC when the reference voltage Vc is the ground potential (0 V). An AC voltage signal is shown as an example.

  As shown in FIG. 5A, the second bending drive signal SBb is an AC voltage signal delayed by 180 degrees in phase with respect to the first bending drive signal SBa, and the second bending drive signal SBb The voltage is equal to a voltage obtained by inverting the sign of the first bending drive signal SBa around the reference voltage Vc. Hereinafter, the voltage of the first bending drive signal SBa is also expressed as SBa, and the voltage of the second bending drive signal SBb is also expressed as SBb = −SBa.

  As shown in FIG. 5B, the longitudinal drive signal SSV is generated by the phase adjustment circuit (not shown) included in the longitudinal vibration drive circuit 336 with respect to the first bending drive signal SBa and the second bending drive signal SBb. The signal is adjusted in phase. In the example shown in the figure, the phase is advanced by 90 degrees with respect to the first bending drive signal SBa and the phase is delayed by 90 degrees with respect to the second bending drive signal SBb. The longitudinal drive signal SSV can be adjusted, for example, in the range of −180 degrees to +180 degrees with respect to the first bending drive signal SBa and the second bending drive signal SBb. Hereinafter, the voltage of the vertical drive signal SSV is also expressed as SSV.

  FIG. 6 is an explanatory diagram showing an example of the waveform of the AC drive voltage SAC. The AC drive voltage SAC in FIG. 6A is a sine wave. The AC drive voltage SAC in FIGS. 6B and 6C is not a sine wave, but has a periodic waveform. As can be understood from these examples, the AC drive voltage SAC and the AC components of the drive signals SBa, SBb, and SSV generated based on the AC drive voltage SAC need only change periodically, and various waveforms are available. Can be used.

  In the piezoelectric driving unit 10, the first bending drive signal SBa is supplied to the first piezoelectric elements 110a and 110d, the second bending drive signal SBb is supplied to the second piezoelectric elements 110b and 110c, and the longitudinal driving is performed. When the signal SSV is supplied to the third piezoelectric element 110e, the operation is as described below.

A2. Operation of the piezoelectric drive:
<Vertical vibration operation (during weak braking)>
FIG. 7 is an explanatory diagram schematically showing the longitudinal vibration operation of the piezoelectric drive unit 10. In FIG. 7, the illustration of the diaphragm 200 is omitted for convenience. The piezoelectric driving unit 10 supplies the vertical driving signal SSV to the third piezoelectric element 110e (element shown by cross-hatching) in the center, so that the vibrating body part 210 (FIG. 3) of the diaphragm 200 extends along the longitudinal direction. The projection 20 operates in a stretching vibration (hereinafter also referred to as “longitudinal vibration”) that vibrates along the longitudinal direction.

  In FIG. 7A, the longitudinal vibration will be described with reference to the state P0 of the piezoelectric drive unit 10 when the voltage of the longitudinal drive signal SSV is the reference voltage Vc. In the state of SSV> Vc, the third piezoelectric element 110e extends in the longitudinal direction, and the vibrating body portion 210 (FIG. 3) of the diaphragm 200 extends in the longitudinal direction in the plane, and becomes PS1, and SSV <Vc. In the state, the third piezoelectric element 110e is contracted along the longitudinal direction, and the vibrating body portion 210 is contracted in the longitudinal direction within the plane PS2. As a result, the piezoelectric drive unit 10 is in a vibration state in which the protrusion 20 is alternately deformed into a stretched state and a contracted state in accordance with the supplied vertical drive signal SSV. In this way, the vibration operation that alternately changes along the longitudinal direction is “longitudinal vibration”. This longitudinal direction is also referred to as “longitudinal vibration direction”. The amplitude of this longitudinal vibration depends on the voltage amplitude of the longitudinal drive signal SSV, and increases as the voltage amplitude increases, and conversely decreases as the voltage amplitude decreases.

  In a state where the driven body 50 is operated (rotated in this example), when the piezoelectric drive unit 10 is longitudinally vibrated as shown in FIG. 7A, as shown in FIG. Repeatedly presses the outer peripheral surface of the driven body 50 (left side in FIG. 7B) and the projection 20 is separated from the driven body 50 (right side in FIG. 7B). The driver 50 can be braked. The driving operation of the piezoelectric driving unit 10 for operating the driven body 50 will be described later.

  While the protrusion 20 is pressing the driven body 50 (left side in FIG. 7B), a frictional force (dynamic frictional force) Fk corresponding to the pressing force Nf is generated. The frictional force Fk acts as a braking force on the driven body 50 that is moving (rotating in this example), and can brake the driven body 50. On the other hand, when the protrusion 20 is separated from the driven body 50 (on the right side of FIG. 7B), the frictional force Fk is not generated, so that the braking force is applied to the driven body 50. Absent. As a result, in the case of longitudinal vibration, the effective braking force is smaller than in the case where the driving of the piezoelectric driving unit 10 is stopped and the protrusion 20 constantly presses the driven body 50. In particular, since the time during which the protrusion 20 contacts the driven body 50 in the longitudinal vibration is very short, the effective braking force is further reduced by this. Therefore, in the case of longitudinal vibration, a gentle (smooth) deceleration can be executed as compared with the braking when the driving of the piezoelectric driving unit 10 is stopped.

  The braking force due to the longitudinal vibration can be adjusted by changing the magnitude of the voltage amplitude of the longitudinal drive signal SSV. For example, as the amplitude of the voltage is increased and the amplitude of the vibration is increased, the pressing force is increased, so that the braking force is increased and the degree of deceleration is increased. On the other hand, as the drive voltage is reduced and the vibration amplitude is reduced, the pressing force is reduced, so that the braking force is reduced and the degree of deceleration is reduced.

<Bending vibration operation (during moderate braking)>
FIG. 8 is an explanatory diagram schematically showing the bending vibration operation of the piezoelectric driving unit 10. Also in FIG. 8, the illustration of the diaphragm 200 is omitted as in FIG. 7. A first bending drive signal SBa is supplied to the pair of first piezoelectric elements 110a and 110d (elements shown by hatching diagonally to the left), which is the first diagonal of the piezoelectric drive unit 10, and the second pair The second bending drive signal SBb is supplied to the other pair of second piezoelectric elements 110b and 110c (elements shown by hatching diagonally downward to the right) that are corners. Thereby, the vibrating body portion 210 of the diaphragm 200 bends in the width (lateral) direction intersecting with the longitudinal direction, and the projection portion 20 operates in the lateral vibration in which the vibration occurs along the width direction (hereinafter also referred to as “bending vibration”). To do.

  In FIG. 8A, description will be made with reference to the state P0 of the piezoelectric driving unit 10 when SBa = SBb = Vc. In the state of SBa> Vc, SBb (= −SBa) <Vc, the first piezoelectric elements 110a and 110d extend in the longitudinal direction, and the second piezoelectric elements 110b and 110c contract in the longitudinal direction. Accordingly, the first piezoelectric element 110a and the second piezoelectric element 110c that are line-symmetric with respect to the longitudinal center line CX, and the first piezoelectric element 110d and the second piezoelectric element 110b, respectively. In the opposite deformation, the first piezoelectric element 110a and the second piezoelectric element 110b along the center line CX, and the second piezoelectric element 110c and the first piezoelectric element 110d are opposite to each other. It becomes the deformation of. Therefore, the piezoelectric drive unit 10 is in a meandering (S-shaped) state PB1 in which the vibrating body unit 210 is bent in the plane. On the other hand, in the state of SBa <V0, SBb (= −SBa)> Vc, the first piezoelectric elements 110a and 110d are contracted in the longitudinal direction, and the second piezoelectric elements 110b and 110c are expanded in the longitudinal direction. The drive unit 10 is in a meandering (S-shaped) state PB2 opposite to the state PB1. Accordingly, the piezoelectric driving unit 10 is in a vibration state in which the meandering direction is alternately deformed in the opposite direction in accordance with the supplied first bending driving signal SBa and second bending driving signal SBb. The position of the protrusion 20 changes in the width direction. As described above, in the bending vibration, the bending direction of the piezoelectric driving unit 10 (vibrating body part 210) is alternately changed along the width direction, and the position of the protrusion 20 of the piezoelectric driving unit 10 vibrates along the width direction. Is the action. The three connection portions 220 of the diaphragm 200 described with reference to FIG. 3 are provided at the positions of the vibration nodes of the vibrating body portion 210. This width direction (short direction) is also referred to as “bending vibration direction”. The amplitude of this bending vibration depends on the voltage amplitude of the first bending drive signal SBa and the second bending drive signal SBb, and increases as the voltage amplitude increases, and conversely decreases as the voltage amplitude decreases.

  In a state where the driven body 50 is operated (rotated in this example), when the piezoelectric driving unit 10 is bent and vibrated as shown in FIG. 8A, as shown in FIG. Repeatedly slide the outer peripheral surface of the driven body 50 (left side of FIG. 8B) and the state where the protrusion 20 is separated from the driven body 50 (right side of FIG. 8B), The driven body 50 can be braked. The driving operation of the piezoelectric driving unit 10 for operating the driven body 50 will be described later.

  While the protrusion 20 is sliding on the driven body 50 (left side of FIG. 8B), the rotation of the driven body 50 is performed while the protrusion 20 is in contact with the driven body 50. Correspondingly, a deformation force Nr against the deformation force Nd applied to the protrusion 20 (a force for deforming the protrusion 20) Nd is generated. The deformation drag Nr acts as a braking force on the driven body 50 that is moving (rotating in this example), and can brake the driven body 50. However, this deformation resistance Nr is weaker than the frictional force (dynamic frictional force and static frictional force) caused by the pressing force of the protrusion 20 pressing the driven member 50 when the piezoelectric driving unit 10 is driven. Further, when the protrusion 20 is separated from the driven body 50 and is not slid (right side in FIG. 8B), the deformation drag Nr is not generated and the braking force is applied to the driven body 50. Absent. As a result, even in the case of flexural vibration, the effective braking force is reduced as compared with the case where the driving of the piezoelectric driving unit 10 is stopped and the protrusion 20 constantly presses the driven body 50. Therefore, in the case of bending vibration, it is possible to execute a gentle (smooth) deceleration by suppressing the braking force, compared to the braking when the driving of the piezoelectric driving unit 10 is stopped.

  Here, the braking force due to the bending vibration is based on the deformation drag Nr while the protrusion 20 is sliding, as described above. Further, as described above, the braking force due to the longitudinal vibration is based on the frictional force Fk while the piezoelectric driving unit 10 is extended and the protrusion 20 is in contact with the driven body. As described above, the deformation resistance Nr is smaller than the frictional force Fk. Therefore, simply, it is considered that the braking force due to bending vibration is weaker than the braking force due to longitudinal vibration. However, the time during which the protrusion 20 is in contact with the driven body 50 in the longitudinal vibration is much shorter than the time during which the protrusion 20 slides on the driven body 50 in the bending vibration. For this reason, as an effective braking force, the braking force due to flexural vibration is larger than the braking force due to longitudinal vibration, specifically about twice as large. Accordingly, braking by bending vibration has a greater deceleration slope than braking by longitudinal vibration.

  The braking force due to the bending vibration can be adjusted by changing the magnitude of the voltage amplitude of the bending drive signals SBa and SBb and the DC offset. For example, as the voltage amplitude is increased and the vibration amplitude is increased, the sliding time is shortened, so that the braking force is reduced and the degree of deceleration is reduced. On the other hand, as the voltage amplitude is reduced and the vibration amplitude is reduced, the sliding time becomes longer. Therefore, the braking force is increased and the degree of deceleration is increased. Further, since the degree of contact of the protrusion 20 with the driven body 50 can be increased as the DC offset is increased, the force for sliding the driven body 50 is increased, and the braking force is increased accordingly. On the other hand, the lower the DC offset, the weaker the degree of contact of the protrusion 20 with the driven body 50, so that the force of sliding the driven body 50 becomes weaker, and the braking force is accordingly increased. become weak.

  As described above, the driven body 50 can be braked also by bending vibration driving. However, in the case of longitudinal vibration drive, the vibration is in the longitudinal direction with respect to the driven body 50, and since the contact time with the driven body 50 is short, the driven body 50 is in contact with the driven body 50. Since the pressing force applied to the surface tends to increase, the contact surface between the protrusion 20 and the driven body 50 is likely to deteriorate due to the impact when pressed, and the durability may be lowered. Further, the longitudinal vibration drive has a smaller braking force than the flexural vibration drive, and the effect of adjusting the braking force is also small. Therefore, it can be said that the braking by the bending vibration driving is more effective in terms of the braking effect, the braking adjustment effect, and the durability than the braking by the longitudinal vibration driving. Note that if the application of voltage to all the piezoelectric elements 110a to 110e is stopped to stop the operation of the piezoelectric drive unit 10, the protrusion 20 is strong by maintaining the pressed state against the driven body 50. It can be braking. However, in this case, as described in the problem, an excessive braking force works, resulting in a rapid deceleration operation.

  It should be noted that either the braking by the bending vibration or the braking by the longitudinal vibration can be executed by switching by the drive selection circuit 338 according to the desired braking. For example, in the case of weak braking, braking by longitudinal vibration can be used, and in the case of moderate braking, braking by bending vibration can be used. Moreover, you may make it switch in the middle of braking operation | movement.

<Oval vibration operation (during normal driving)>
FIG. 9 is an explanatory diagram schematically showing the elliptical vibration operation of the piezoelectric drive unit 10. 9 also omits the illustration of the diaphragm 200 as in FIG. A first bending drive signal SBa is supplied to the pair of first piezoelectric elements 110a and 110d (elements shown by hatching diagonally to the left), which is the first diagonal of the piezoelectric drive unit 10, and the second pair The second bending drive signal SBb is supplied to the other pair of second piezoelectric elements 110b and 110c (elements shown by hatching diagonally downward to the right) that are corners. Further, the vertical drive signal SSV is also supplied to the third piezoelectric element 110e at the center. As a result, both the bending vibration and the longitudinal vibration described above are combined, and the protrusion 20 operates with an elliptical vibration that moves so as to draw a substantially elliptical locus. In the example shown in the figure, it is counterclockwise when viewed from the front side of the drawing. In the following description, unless otherwise specified, the direction of rotation is based on the case viewed from the front side of the page. The direction of this movement is such that the phase of the longitudinal drive signal SSV shown in FIG. 5 is delayed by 90 degrees with respect to the first bending drive signal SBa and delayed by 90 degrees with respect to the second bending drive signal SBb. If it is a signal, it can be clockwise. Note that the phase delay and advance are not limited to 90 degrees, and may be various other numerical values, and the shape and direction of the locus of the ellipse can be changed according to the phase value.

  When the piezoelectric driving unit 10 is caused to elliptically vibrate as shown in FIG. 9A during normal driving in which the driven body 50 operates (rotates in this example), as shown in FIG. It moves so that 20 draws the locus of an ellipse. At this time, as shown on the left side of FIG. 9B, while the protrusion 20 is in contact with the driven body 50, the driven body 50 slides to generate a driving force, and FIG. As shown on the right side of the figure, the ellipse trajectory is traced without sliding the driven body 50 while the protrusion 20 is separated from the driven body 50. Thereby, the protrusion part 20 of the piezoelectric drive part 10 can slide the to-be-driven body 50 only to a fixed direction, and can rotate the to-be-driven body 50 according to this to a fixed direction. In this example, it rotates clockwise according to the locus of the ellipse of the protrusion 20. The normal driving means a case where the driven body (rotor in this example) 50 is driven (rotated) in an accelerated state or a constant speed state by the piezoelectric driving unit 10.

  In addition, by supplying the first bending drive signal SBa to the pair of first piezoelectric elements 110a and 110d at the first diagonal, the piezoelectric drive unit 10 is caused to counterclockwise elliptically vibrate, and the driven body 50 is driven. Can also be driven clockwise. Further, by supplying the second bending drive signal SBb to the other pair of second piezoelectric elements 110b and 110c at the second diagonal, the piezoelectric drive unit 10 is caused to rotate in the clockwise direction, and the driven body is driven. It is also possible to drive 50 counterclockwise. Further, if the longitudinal drive signal SSV is supplied to the third piezoelectric element 110e in the center, a large amount of longitudinal vibration components are added, and the force applied from the protrusion 20 to the driven body 50 can be further increased. Such an operation of the piezoelectric drive unit 10 (or the piezoelectric vibrator 100) is described in the prior art document (Japanese Patent Application Laid-Open No. 2004-320979 or the corresponding US Pat. No. 7,224,102). The disclosure is incorporated by reference.

<Bending vibration direction>
FIG. 10 is an explanatory diagram showing the vibration direction of the bending vibration of FIG. FIG. 10A shows bending vibration (bending vibration A) when the first bending drive signal SBa is supplied only to the first piezoelectric elements 110a and 110d as a reference example, and FIG. 10B shows a reference example. The bending vibration (bending vibration B) when the second bending driving signal is supplied only to the second piezoelectric elements 110b and 110c is shown. FIG. 10C shows the direction of bending vibration in FIG.

  In the bending vibration A, as shown in FIG. 10A, the first bending drive signal SBa is supplied to the pair of first piezoelectric elements 110a and 110d (elements indicated by hatching) at the first diagonal. No driving signal is supplied to the other pair of second piezoelectric elements 110b and 110c and the central third piezoelectric element 110e at the second diagonal. In this case, the vibration generated in the vibrating body part 210 of the piezoelectric drive unit 10 includes not only the component in the width direction (bending vibration direction) but also the component in the longitudinal direction (longitudinal vibration direction). The elliptical vibration VRA is a counterclockwise ellipse as viewed from the front, and draws a locus of an ellipse whose major axis is inclined diagonally to the left.

  In the bending vibration B, as shown in FIG. 10B, the second bending drive signal SBb is applied to the pair of second piezoelectric elements 110b and 110c (elements indicated by hatching) at the second diagonal. The drive signal is not supplied to the pair of first piezoelectric elements 110a and 110d and the central third piezoelectric element 110e that are supplied and are located at the first diagonal. In this case, the vibration generated in the vibrating body part 210 of the piezoelectric driving unit 10 is similarly an elliptical vibration VRB. However, the elliptical vibration VRB is, for example, a locus in which the major axis is inclined obliquely in the upper left direction in the clockwise direction opposite to the elliptical vibration VRA when viewed from the front side of the drawing.

  The bending vibration shown in FIG. 8 is obtained by executing the elliptical vibration of the bending vibration A shown in FIG. 10A and the elliptical vibration of the bending vibration B shown in FIG. 10B. However, the second bending drive signal SBb supplied to the second piezoelectric elements 110b and 110c is a differential signal that is 180 degrees out of phase with the first bending drive signal SBa. Are different by 180 degrees, and the vibration reference point Sr is different by 180 degrees. For this reason, as shown in FIG. 10C, the flexural vibration of FIG. 8 cancels the longitudinal vibration component (longitudinal vibration) and becomes a lateral vibration only in the width direction, not the elliptical vibration. Note that the elliptical trajectory of the bending vibration A and the elliptical trajectory of the bending vibration B shown in FIG. 10C have the inclination of the major axis shown in FIGS. 10A and 10B for convenience of explanation. Ignored.

<In free mode>
In a state where the driving of the driven unit 50 is stopped and the operation of the driven unit 50 is stopped, the projection 20 of the piezoelectric driving unit 10 normally keeps pressing the driven unit 50 and is generated by the pressing force. The driven body 50 is in a fixed state (also referred to as “locked state”) by the holding force corresponding to the frictional force to be generated. For this reason, it is often difficult to manually move the device connected to the driven body 50 by applying an external force to the arm of the robot. Therefore, it is preferable that an apparatus using a piezoelectric drive device is provided with a state (so-called “free mode”) in which the fixed state is released and the device can be manually moved by an external force. In an apparatus having this free mode, for example, an arm of a robot, an operation for storing the movement of the arm, so-called “teaching” is possible.

  Here, in the above-described longitudinal vibration (FIG. 7), the braking of the driven body 50 by the longitudinal vibration has been described as an example. This can be reduced by causing the drive unit 10 to vibrate longitudinally.

  Although not shown, the holding force is generated based on the static frictional force generated by the pressing force of the protruding portion 20. Like the braking force, the protruding portion 20 is driven 50 by the longitudinal vibration. The effective holding force can be reduced by generating the holding force only while pressing. Then, by applying an external force larger than the effective holding force to the driven body 50 (actually, a device connected to the driven body 50), the driven body 50 can be manually moved. . Therefore, the free mode can be realized by using the longitudinal vibration.

  In the above-described bending vibration (FIG. 8), braking of the driven body 50 by bending vibration has been described as an example. However, the holding force for holding the driven body 50 is also piezoelectrically driven as in the case of longitudinal vibration. It can be reduced by bending vibration of the portion 10.

  Although not shown, in bending vibration, the deformation drag Nr (FIG. 8) acts as a holding force, and unless an external force larger than this holding force is applied, it is not possible to move the device to which the driven body 50 is connected. Can not. Here, as described above, the deformation resistance Nr is larger than the frictional force (static frictional force and dynamic frictional force) due to the pressing force with which the protrusion 20 presses the driven body 50 when the piezoelectric driving unit 10 is driven. weak. Moreover, since it does not generate | occur | produce during the non-sliding state which the protrusion part 20 is not contacting the to-be-driven body 50, effective holding force becomes smaller than the holding force by deformation | transformation drag Nr. Therefore, the driven body 50 is manually moved by applying an external force larger than the effective holding force based on the deformation drag Nr to the driven body 50 (actually, a device connected to the driven body 50). Is possible. Therefore, the free mode can be realized by using the bending vibration.

  The holding force due to the bending vibration is also larger than the holding force due to the longitudinal vibration, specifically about twice as large as the braking force. Therefore, when the apparatus is manually moved lightly with a smaller external force, it is preferable to use the longitudinal vibration in the free mode. On the other hand, when the apparatus is moved manually while feeling the weight of the apparatus or when it is desired not to move the apparatus excessively due to excessive force, it is preferable to use the bending vibration in the free mode. Further, switching may be performed in the middle, such as longitudinal vibration drive when moving a large amount and bending vibration drive when moving a small amount.

  Also, the braking operation may use bending vibration drive, and the free mode operation may use longitudinal vibration drive.

  As can be seen from the above description, in this embodiment, the first and second bending drive signals SBa, SBb correspond to the first and second drive signals of the invention, and the vertical drive signal SSV is the third. This corresponds to the drive signal.

B. Piezoelectric drive device of the second embodiment:
B1. Piezoelectric drive configuration:
FIG. 11 is an explanatory diagram showing a schematic configuration of the piezoelectric drive unit 10B and the drive circuit 300B in the piezoelectric drive device 1000B of the second embodiment. The driven body 50 is not shown.

  The piezoelectric drive unit 10B is the same as the piezoelectric drive unit 10 except that the third piezoelectric element 110e at the center of the piezoelectric drive unit 10 (see FIG. 2) is not provided. That is, the piezoelectric drive unit 10B includes a pair of first piezoelectric elements 110a and 110d at a first diagonal and a pair of second piezoelectric elements 110b and 110c at a second diagonal. The piezoelectric element has a structure that is symmetrical with respect to the center line CX of the piezoelectric vibrating body 100.

  The drive circuit 300B includes an AC drive voltage generation circuit 332, a bending vibration drive circuit 334, a longitudinal vibration drive circuit 336, and a drive selection circuit 338B. The functions of the AC drive voltage generation circuit 332, the bending vibration drive circuit 334, and the longitudinal vibration drive circuit 336 are the same as those of the drive circuit 300 (FIG. 4) in the first embodiment, and the description thereof is omitted here. .

  The drive selection circuit 338B includes two differential bending drive signals SBa and SBb generated by the bending drive circuit 334 by a combination of the first selection circuit SW11, the second selection circuit SW12, and the third selection circuit SW13. Select a supplier. Specifically, only the first bending driving signal SBa is selected as the first driving signal Sa, only the first bending driving signal SBa is selected as the second driving signal Sb, or the first bending driving is performed. The signal SBa is selected as the first drive signal Sa and the second bending drive signal SBb is selected as the second drive signal Sb, or neither is selected. In addition, when the drive selection circuit 338B does not select the two bending drive signals SBa and SBb, the fourth selection circuit SW14 uses the longitudinal drive signal SSV generated by the longitudinal vibration drive circuit 336 as the first drive signal Sa. And the second drive signal Sb.

  The first drive signal Sa is supplied to the second electrodes 150a and 150d of the first pair of first piezoelectric elements 110a and 110d via the wiring 314, and the second drive signal Sb is The electric power is supplied to the second electrodes 150b and 150c of the pair of second piezoelectric elements 110b and 110c in the second diagonal via the wiring 310. A reference voltage (= 0V) having the same potential as the ground potential of the drive circuit 300B is supplied to the first electrode 130 through the wiring 320 as a reference voltage signal SC.

  As will be described later, the piezoelectric driving unit 10B vibrates in one of longitudinal vibration, bending vibration, and elliptical vibration based on the supplied first driving signal Sa and second driving signal Sb, and enters this vibration state. Accordingly, the driven body 50 is driven.

B2. Operation of the piezoelectric drive:
<Oval vibration operation>
FIG. 12 is an explanatory diagram showing the elliptical vibration operation of the piezoelectric drive unit 10B. FIG. 12A shows the case where the first selection circuit SW11 of the drive selection circuit 338B (FIG. 11) is selected (ON) and the second to fourth selection circuits SW12 to SW14 are not selected (OFF). An elliptical vibration drive A is shown. In this case, since the first bending drive signal SBa is selected as the first drive signal Sa (FIG. 11) and supplied to the first piezoelectric elements 110a and 110d (elements indicated by hatching), piezoelectric drive is performed. The protrusion 10 of the part 10B can vibrate along the locus of the elliptical vibration VRA (FIG. 10). Thereby, the piezoelectric drive part 10B can drive the driven body (rotor) 50, and can rotate the driven body 50 clockwise.

  In contrast, in FIG. 12B, the second selection circuit SW12 of the drive selection circuit 338B is selected (ON), and the first, third, and fourth selection circuits SW11, SW13, and SW14 are not selected ( The elliptical vibration drive B in the case of “OFF” is shown. In this case, since the first bending drive voltage SBa is selected as the second drive signal Sb (FIG. 11) and supplied to the second piezoelectric elements 110b and 110c (elements indicated by hatching), piezoelectric drive is performed. The protrusion 10 of the part 10B can vibrate along the locus of the elliptical vibration VRA (FIG. 10). Thereby, the piezoelectric drive part 10B can drive the driven body (rotor) 50, and can rotate the driven body 50 counterclockwise.

<Bending vibration operation>
FIG. 13 is an explanatory diagram showing the bending vibration operation of the piezoelectric drive unit 10B. The piezoelectric drive unit 10B selects (ON) the first and third selection circuits SW11 and SW13 of the drive selection circuit 338B (FIG. 11) and does not select (OFF) the second and fourth selection circuits SW12 and SW14. Thus, it is possible to drive bending vibration. In this case, the first bending drive voltage SBa is selected as the first drive signal Sa, supplied to the first piezoelectric elements 110a and 110d (elements shown by hatching upward to the right), and the differential voltage A certain second bending drive voltage SBb is selected as the second drive signal Sb, and is supplied to the second piezoelectric elements 110b and 110c (elements shown by hatching downward to the right). Accordingly, the piezoelectric driving unit 10B can be flexibly vibrated along the width direction as described in the piezoelectric driving unit 10 of the first embodiment (FIG. 8). Accordingly, the piezoelectric drive unit 10B can gently brake the driven body 50 and can implement a free mode operation, similarly to the piezoelectric drive unit 10 of the first embodiment (FIG. 8).

<Vertical vibration drive>
FIG. 14 is an explanatory diagram showing the longitudinal vibration operation of the piezoelectric drive unit 10B. The piezoelectric drive unit 10B deselects (OFF) the first to third selection circuits SW11 to SW13 of the drive selection circuit 338B (FIG. 11), and selects (ON) the fourth selection circuit SW14. It can be driven by longitudinal vibration. In this case, the first bending drive signal SBa is selected as the first and second drive signals Sa and Sb, and the first piezoelectric elements 110a and 110d and the second piezoelectric elements 110b and 110c (all hatched areas) are selected. Device). As a result, the first piezoelectric elements 110a and 110d and the second piezoelectric elements 110b and 110c operate in the same manner as the third piezoelectric element 110e of the piezoelectric driving unit 10 of the first embodiment (FIG. 7), and in the longitudinal direction. Can be vibrated longitudinally. Accordingly, the piezoelectric drive unit 10B can gently brake the driven body 50 and can implement a free mode operation, similarly to the piezoelectric drive unit 10 of the first embodiment (FIG. 7).

  In this embodiment as well, as in the first embodiment, switching by the drive circuit 338B can be performed to perform either braking by bending vibration or braking by longitudinal vibration. For example, in the case of weak braking, braking by longitudinal vibration can be used, and in the case of moderate braking, braking by bending vibration can be used. Moreover, you may make it switch in the middle of braking operation | movement. In addition, the free mode based on the longitudinal vibration drive and the free mode based on the flexural vibration drive can be used in various ways depending on the use situation. Also, the braking operation may use bending vibration drive, and the free mode operation may use longitudinal vibration drive.

  As can be seen from the above description, in this embodiment, the first bending drive signal SBa supplied to the first piezoelectric elements 110a and 110d corresponds to the first drive signal of the invention, and the second piezoelectric element. The second bending drive signal SBb supplied to 110b and 110c corresponds to the second drive signal of the invention. Further, the first bending drive signal SBa supplied to the third piezoelectric element 110e corresponds to the third drive signal of the invention.

C. Other embodiments of the piezoelectric drive:
FIG. 15 is a cross-sectional view of a piezoelectric drive unit 10C as another embodiment of the present invention, and corresponds to FIG. 2B of the first embodiment. In the piezoelectric driving unit 10C, the piezoelectric vibrating body 100 is disposed on the diaphragm 200 in a state where the top and bottom of FIG. That is, here, the second electrode 150 is disposed close to the diaphragm 200 and the substrate 120 is disposed farthest from the diaphragm 200. In FIG. 15, as in FIG. 2B, wiring (or a wiring layer and an insulating layer) for electrical connection between the second electrodes 150 a to 150 e, the first electrode 130, and the second electrode Illustration of wirings (or wiring layers and insulating layers) for electrical connection between 150a to 150e and the drive circuit is omitted. This piezoelectric drive unit 10C can also achieve the same effects as in the first embodiment.

  FIG. 16A is a schematic plan view of a piezoelectric drive unit 10D as still another embodiment of the present invention, and corresponds to FIG. 8 of the first embodiment. 16A and 16B, for convenience of illustration, the connection part 220 and the attachment part 230 of the diaphragm 200 are not shown. In the piezoelectric drive unit 10D of FIG. 16A, differential bending is performed with respect to the first piezoelectric element 110a and the second piezoelectric element 110c (elements indicated by hatching) symmetrical to the center line CX. The structure which supplies a drive signal is shown. In the piezoelectric drive 10E of FIG. 16B, differential bending drive is performed with respect to the first piezoelectric element 110d and the second piezoelectric element 110b (elements indicated by hatching) symmetrical to the center line CX. The structure which supplies a signal is shown. However, in these configurations, the wires 151 and 152 in the piezoelectric driving unit 10 (see FIG. 4) are deleted, and independent wires need to be connected to the second electrodes of the respective piezoelectric elements. Also in these piezoelectric driving units 10D and 10E, it is possible to generate a bending vibration that vibrates in the width direction. That is, if a differential voltage is applied to the first and second piezoelectric elements that are symmetrical with respect to the center line CX, bending vibration that vibrates in the width direction can be generated. it can.

D. Embodiments of a device using a piezoelectric drive:
The piezoelectric drive unit described above can apply a large force to the driven body by utilizing resonance, and can be applied to various devices. Piezoelectric driving devices include, for example, robots, electronic component conveying devices (IC handlers), medication pumps, clock calendar feeding devices, printing devices (for example, paper feeding mechanisms. However, in piezoelectric driving devices used for heads, diaphragms Therefore, it can be used as a driving device in various devices. Hereinafter, representative embodiments will be described.

  FIG. 17 is an explanatory diagram showing an example of a robot 2050 using the piezoelectric driving device 1000 described above. The robot 2050 includes a plurality of link portions 2012 (also referred to as “link members”) and an arm 2010 (“a” that includes a plurality of joint portions 2020 that connect the link portions 2012 in a rotatable or bendable state. It is also called “arm”. Each joint unit 2020 incorporates the piezoelectric drive unit 10 of the above-described piezoelectric drive unit 1000, and the joint unit 2020 can be rotated or bent by an arbitrary angle using the piezoelectric drive unit 10. It is. A robot hand 2000 is connected to the tip of the arm 2010. The robot hand 2000 includes a pair of grip portions 2003. The robot hand 2000 also has a built-in piezoelectric driving unit 10, and the piezoelectric driving unit 10 can be used to open and close the gripping unit 2003 to grip an object. The piezoelectric drive unit 10 is also provided between the robot hand 2000 and the arm 2010, and the robot hand 2000 can be rotated with respect to the arm 2010 using the piezoelectric drive unit 10. A drive circuit 300 for controlling each piezoelectric drive unit 10 is included in a control circuit (not shown).

  FIG. 18 is an explanatory diagram of a wrist portion of the robot 2050 shown in FIG. The wrist joint portion 2020 sandwiches the wrist rotating portion 2022, and the wrist link portion 2012 is attached to the wrist rotating portion 2022 so as to be rotatable around the central axis O of the wrist rotating portion 2022. . The wrist rotating unit 2022 includes the piezoelectric driving unit 10, and the piezoelectric driving unit 10 rotates the wrist link unit 2012 and the robot hand 2000 around the central axis O. The robot hand 2000 is provided with a plurality of gripping units 2003. The proximal end portion of the gripping part 2003 is movable in the robot hand 2000, and the piezoelectric drive part 10 is mounted on the base part of the gripping part 2003. For this reason, by operating the piezoelectric drive unit 10, the gripping unit 2003 can be moved to grip the object. Further, by operating the piezoelectric drive unit 10 in the free mode, the arm 2010 and the wrist can be manually operated (so-called “teaching”), and the operation to be executed by the robot 2050 can be stored.

  The robot is not limited to a single-arm robot, and the piezoelectric drive unit 10 can be applied to a multi-arm robot having two or more arms. Here, in the wrist joint 2020 and the robot hand 2000, in addition to the piezoelectric drive unit 10, a power line for supplying power to various devices such as a force sensor and a gyro sensor, a signal line for transmitting a signal, and the like And requires a lot of wiring. Therefore, it is very difficult to arrange the wiring inside the joint portion 2020 and the robot hand 2000. However, since the piezoelectric drive unit 10 of the above-described embodiment can reduce the drive current as compared with a normal electric motor or a conventional piezoelectric drive device, the joint unit 2020 (particularly, the joint unit at the tip of the arm 2010) or a robot hand. Wiring can be arranged even in a small space such as 2000.

  FIG. 19 is an explanatory diagram showing an example of a liquid feed pump 2200 using the piezoelectric driving device 1000 described above. In the case 2230, the liquid feed pump 2200 includes a reservoir 2211, a tube 2212, a piezoelectric drive unit 10, a rotor 2222, a deceleration transmission mechanism 2223, a cam 2202, a plurality of fingers 2213, 2214, 2215, 2216, 2217, 2218, and 2219 are provided. The drive circuit 300 is not shown. The reservoir 2211 is a storage unit for storing a liquid to be transported. The tube 2212 is a tube for transporting the liquid sent out from the reservoir 2211. The protrusion 20 of the piezoelectric drive unit 10 is provided in a state of being pressed against the side surface of the rotor 2222, and the piezoelectric drive unit 10 rotationally drives the rotor 2222. The rotational force of the rotor 2222 is transmitted to the cam 2202 via the deceleration transmission mechanism 2223. Fingers 2213 to 2219 are members for closing the tube 2212. When the cam 2202 rotates, the fingers 2213 to 2219 are sequentially pushed outward in the radial direction by the protrusion 2202A of the cam 2202. The fingers 2213 to 2219 close the tube 2212 in order from the upstream side in the transport direction (reservoir 2211 side). Thereby, the liquid in the tube 2212 is transported to the downstream side in order. In this way, it is possible to realize a small liquid feed pump 2200 that can deliver an extremely small amount with high accuracy and that is small. In addition, arrangement | positioning of each member is not restricted to what was illustrated. Further, a member such as a finger may not be provided, and a ball or the like provided on the rotor 2222 may close the tube 2212. The liquid feed pump 2200 as described above can be used for a medication device that administers a drug solution such as insulin to the human body. Here, by using the piezoelectric drive unit device 1000 of the above-described embodiment, the drive current is smaller than that of the conventional piezoelectric drive device, so that the power consumption of the dosing device can be suppressed. Therefore, it is particularly effective when the medication apparatus is battery-driven.

E. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(1) In the above embodiment, the first electrode 130, the piezoelectric body 140, and the second electrode 150 are formed on the substrate 120. However, the substrate 120 is omitted and the first electrode is formed on the vibration plate 200. 130, the piezoelectric body 140, and the second electrode 150 may be formed.

(2) In the above embodiment, one piezoelectric vibrating body 100 is provided on each of both surfaces of the vibration plate 200, but one of the piezoelectric vibrating bodies 100 can be omitted. However, providing the piezoelectric vibrating bodies 100 on both surfaces of the diaphragm 200 is preferable in that it is easier to deform the diaphragm 200 into a meandering shape bent in the plane.

(3) In each of the above embodiments, the piezoelectric element that uses a piezoelectric body formed by a film forming process has been described as an example. However, the piezoelectric body may be a bulk piezoelectric body.

(4) In the above-described embodiment, the configuration in which the vibration body portion 210 is supported by the connection portions 220 extending from the left and right long sides of the vibration body portion 210 so as to be able to vibrate is described as an example. The position and number are not limited to this, and various arrangement positions and numbers can be adopted. For example, a connection part may be provided only on one side along the longitudinal direction, and the vibrating body part 210 may be supported in a cantilever state. In addition, a connection portion may be provided on the short side of the vibrating body portion 210 opposite to the protruding portion 20 to support the vibrating body portion 210 in a cantilever state.

(5) In the above embodiment, the phase of the first drive signal supplied to the first piezoelectric elements 110a and 110d and the second drive signal supplied to the second piezoelectric elements 110b and 110c in bending vibration is 180. The example has been described using differential voltage signals of different degrees. However, the first drive vibration and the second drive signal are not limited to differential voltage signals. The bending vibration drive circuit 334 includes an adjustment circuit that changes the amplitude, phase difference, and DC offset of each of the two bending drive signals SBa and SBb, and signals having various phase differences and voltages having different amplitudes. Or a signal with a different DC offset. By adjusting the phase difference, amplitude, DC offset, etc. between the first drive signal and the second drive signal, compensation of the characteristic difference between the first piezoelectric element and the second piezoelectric element, and the combination of the piezoelectric drive unit It is possible to compensate for misalignment of the attached position. In addition, it is possible to change the position of the neutral point of vibration, and in free mode by bending vibration or longitudinal vibration, the contact force of the contact part to the driven body is changed to move the device connected to the driven body. The external force for changing can be changed.

(6) In the above embodiment, drive signals for bending vibration and longitudinal vibration are generated based on the AC drive voltage SAC that is a voltage signal having a frequency close to the mechanical resonance frequency of the piezoelectric drive unit 10, and AC drive is performed. Although the signal has the same frequency (cycle) as the voltage SAC, for example, the frequency (cycle) of the longitudinal drive signal in the case of braking by longitudinal vibration may be higher than the frequency of the flexural drive signal of flexural vibration.

(7) In the above-described embodiment, the configuration in which a pair of piezoelectric vibrating bodies is joined to the diaphragm has been described as an example. However, the number of piezoelectric vibrating bodies may be one. Moreover, it is good also as a structure which laminated | stacked the some piezoelectric vibrating body.

(8) In the above-described embodiment, the configuration in which the piezoelectric vibrating body is provided on the diaphragm has been described as an example, but the diaphragm is not an essential configuration and may be omitted.

(9) In the above-described embodiment, the configuration in which the protrusion (contact portion) is provided on one short side along the width direction intersecting with the longitudinal direction of the piezoelectric vibrator has been described as an example. A configuration in which a protruding portion (contact portion) is provided on the other long side may be employed.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

1000, 1000B ... Piezoelectric drive device 10, 10B, 10C, 10D, 10E ... Piezoelectric drive device 12 ... Tube 20 ... Projection (contact portion, action portion)
50 ... Rotor (driven body)
DESCRIPTION OF SYMBOLS 51 ... Center of driven body 100 ... Piezoelectric vibrator 110a, 110b, 110c, 110d, 110e ... Piezoelectric element 120 ... Substrate 125 ... Insulating layer 130 ... First electrode 140 ... Piezoelectric body 150, 150a, 150b, 150c, 150d, 150e ... second electrode 151,152 ... wiring 200 ... diaphragm 201 ... center of vibrating body part (vibrating plate) 202 ... center line 210 ... vibrating body part 220 ... connecting part 230 ... mounting part 240 ... screw 300, 300B ... drive Circuits 310, 312, 314, 320 ... wiring 332 ... AC drive voltage generation circuit 334 ... flexural vibration drive circuit 336 ... longitudinal vibration drive circuit 338, 338B ... drive selection circuit 2000 ... robot hand 2003 ... gripping part 2010 ... arm 2012 ... link Part 2020 ... joint part 2022 ... wrist rotation part 2050 ... robot 2200 ... Liquid feed pump 2202 ... Cam 2202A ... Projection 2211 ... Reservoir 2212 ... Tube 2213 ... Finger 2222 ... Rotor 2223 ... Deceleration transmission mechanism 2230 ... Case SW1, SW2 ... Selection circuit SW11, SW12, SW13, SW14 ... Selection circuit

Claims (10)

A piezoelectric drive for driving the driven body;
A drive circuit for driving the piezoelectric drive unit;
With
The piezoelectric drive unit is
A piezoelectric vibrator having a first piezoelectric element and a second piezoelectric element;
A contact portion that contacts the driven body;
The piezoelectric vibrating body includes:
At least a part of the first piezoelectric element is disposed on one side with respect to a center line along the longitudinal direction of the piezoelectric vibrator,
At least a portion of the second piezoelectric element is disposed on the other of the one side with respect to the center line;
The drive circuit is
At least one of when the driven body is stopped or braked, the first piezoelectric element is supplied with a first drive signal whose voltage periodically changes at a predetermined period, and the second piezoelectric element The second drive signal whose voltage periodically changes in the predetermined cycle having a phase different from that of the first drive signal is supplied along the width direction intersecting the longitudinal direction with the contact portion. A piezoelectric drive device characterized by being vibrated. The piezoelectric drive device according to claim 1,
The piezoelectric vibration device is characterized in that the first piezoelectric element and the second piezoelectric element are arranged symmetrically with respect to the center line. The piezoelectric drive device according to claim 2,
In the piezoelectric vibrating body, the first piezoelectric element and the second piezoelectric element are arranged along the longitudinal direction on one side of the piezoelectric element, and the piezoelectric vibrator is arranged along the longitudinal direction on the other side of the piezoelectric element. A piezoelectric driving device comprising a second piezoelectric element and the first piezoelectric element. The piezoelectric drive device according to any one of claims 1 to 3, wherein
The drive circuit includes an adjustment circuit that changes at least one of an amplitude of a voltage of the first drive signal, an amplitude of a voltage of the second drive signal, and a difference between the phases. Drive device. The piezoelectric driving device according to any one of claims 1 to 4, wherein
The piezoelectric vibrating body further includes a third piezoelectric element disposed along the center line,
The drive circuit is at least at the time of stopping or braking,
a) supplying the first drive signal to the first piezoelectric element and supplying the second drive signal to the second piezoelectric element, thereby causing the contact portion to extend along the width direction. Bending vibration to vibrate;
b) Longitudinal vibration that vibrates the contact portion along the longitudinal direction by supplying a third drive signal whose voltage periodically changes at the predetermined period to the third piezoelectric element;
Any one of the above is executed in a switchable manner. The piezoelectric driving device according to any one of claims 1 to 4, wherein
The drive circuit is at least at the time of stopping or braking,
a) supplying the first drive signal to the first piezoelectric element and supplying the second drive signal to the second piezoelectric element, thereby vibrating the contact portion along the width direction. Bending vibration,
b) Vibrating the contact portion along the longitudinal direction by supplying a third drive signal whose voltage periodically changes at the predetermined period to the first piezoelectric element and the second piezoelectric element. With longitudinal vibration,
Any one of the above is executed in a switchable manner. The piezoelectric drive device according to any one of claims 1 to 6, wherein
The contact portion is provided so as to be able to contact the driven body arranged along the longitudinal direction of the piezoelectric vibrating body,
The longitudinal vibration is vibration in which the driven body and the contact portion repeat contact and non-contact along the longitudinal direction,
The first bending vibration and the second bending vibration are vibrations in which the driven body and the contact portion repeat sliding and non-sliding along a direction intersecting with the longitudinal direction, respectively. A piezoelectric drive device. A piezoelectric driving device according to any one of claims 1 to 7,
The piezoelectric driving device according to claim 1, wherein the piezoelectric vibrating body is provided on a diaphragm. A plurality of link portions and a joint portion connecting the plurality of link portions;
The at least one piezoelectric driving device according to any one of claims 1 to 4, wherein the plurality of link portions are rotated by the joint portions.
Robot equipped with. The robot driving method according to claim 9, wherein the plurality of link parts are rotated by the joint parts by driving at least one of the piezoelectric driving devices,
A first drive signal whose voltage periodically changes at a predetermined cycle is supplied to the first piezoelectric element when at least one of the rotation of the plurality of link portions at the joint portion is stopped or during braking. By supplying a second drive signal whose voltage periodically changes in the predetermined cycle having a phase different from that of the first drive signal to the second piezoelectric element, the contact portion is made to be the piezoelectric vibrator. A driving method of a robot, wherein the piezoelectric driving device is driven so as to vibrate along a width direction intersecting with a longitudinal direction of the robot.

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