JP6455017B2 - Piezoelectric driving device and driving method thereof, robot and driving method thereof - Google Patents

Description

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

  A piezoelectric actuator (piezoelectric driving device) that drives a driven body by vibrating a piezoelectric body is used in various fields because it does not require a magnet or a coil (for example, Patent Document 1). The basic configuration of this piezoelectric drive device is a configuration in which four piezoelectric elements are arranged in two rows and two columns on each of two surfaces of the reinforcing plate, and a total of eight piezoelectric elements are included in the reinforcing plate. It is provided on both sides. Each piezoelectric element is a unit in which a piezoelectric body is sandwiched between two electrodes, and the reinforcing plate is also used as one electrode of the piezoelectric element. One end of the reinforcing plate is provided with a protrusion for rotating the rotor in contact with the rotor as a driven body. When an AC voltage is applied to two of the four piezoelectric elements arranged diagonally, the two piezoelectric elements expand and contract, and the protrusion of the reinforcing plate reciprocates or elliptically moves accordingly. I do. And according to the reciprocating motion or elliptical motion of the protrusion of the reinforcing plate, the rotor as the driven body rotates in a predetermined rotation direction. In addition, the rotor can be rotated in the reverse direction by switching the two piezoelectric elements to which the AC voltage is applied to the other two piezoelectric elements.

JP 2004-320979 A

  When a voltage is applied to the piezoelectric driving device, one electrode is grounded and a driving voltage is applied to the other electrode. For this reason, the magnitude of the voltage applied to the piezoelectric body is equal to the magnitude of the output voltage of the drive circuit. Here, when increasing the voltage applied to the piezoelectric body, it is necessary to increase the output voltage of the drive circuit. When increasing the output voltage of the drive circuit, it is necessary to increase the breakdown voltage of the components of the drive circuit.

  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 vibration plate, a first piezoelectric element provided on the vibration plate, and a drive circuit that drives the first piezoelectric element. The first piezoelectric element includes a first electrode, a second electrode, and a piezoelectric body disposed between the first electrode and the second electrode. The drive circuit applies a first drive signal that varies periodically to the first electrode, and applies a second drive signal that varies to the second electrode. According to this embodiment, the amplitude of the voltage applied to the piezoelectric body can be increased or decreased as compared with the case where one electrode is grounded.

(2) In the above embodiment, the first drive signal and the second drive signal may periodically vary. According to this embodiment, the voltage applied to the piezoelectric body can be periodically changed.

(3) In the above aspect, the first drive signal and the second drive signal may be different in at least one of phase, amplitude, and period. According to this embodiment, the amplitude of the voltage applied to the piezoelectric body can be increased or decreased as compared with the case where one electrode is grounded.

(4) In the above aspect, the drive circuit includes a phase of the first drive signal, an amplitude of the first drive signal, a period of the first drive signal, and a phase of the second drive signal. And at least one of the amplitude of the second drive signal and the period of the second drive signal may be variably controlled. According to this embodiment, the amplitude of the voltage applied to the piezoelectric body can be freely changed.

(5) In the above aspect, the drive circuit may have the same period of the first drive signal applied to the first electrode as that of the second drive signal applied to the first electrode. According to this aspect, the period of the voltage applied to the piezoelectric body can be made equal to the period of the drive signal applied to the first electrode or the second electrode.

(6) In the above aspect, the drive circuit may shift the phase of the first drive signal with respect to the phase of the second drive signal. According to this embodiment, the amplitude of the voltage applied to the piezoelectric body can be changed.

(7) In the above embodiment, a second piezoelectric element is further provided. The second piezoelectric element is separated from the first electrode of the first piezoelectric element and the first electrode forming one continuous conductor layer, and the second electrode of the first piezoelectric element. And a second electrode. The drive circuit applies the first drive signal to the first electrode and the second electrode of the second piezoelectric element, and applies the second drive signal to the second electrode of the first piezoelectric element. The drive signal may be applied. According to this aspect, since the amplitude of the voltage applied to the second piezoelectric element becomes zero, of the two piezoelectric elements having the same first electrode, the first piezoelectric element is driven to extend and contract, The piezoelectric element can be prevented from extending and contracting.

(8) In the above aspect, the drive circuit may set the cycle of the first drive signal to N times (N is an integer of 2 or more) or 1 / N of the cycle of the second drive signal. According to this aspect, the cycle of the voltage applied to the piezoelectric body can be made the same as the cycle of the longer drive signal out of the two drive signals.

(9) According to one aspect of the present invention, a robot is provided. The robot includes: a plurality of link units; a joint unit that connects the plurality of link units; and the piezoelectric drive device according to any one of the above aspects, wherein the plurality of link units are rotated by the joint unit. Prepare. According to this embodiment, the piezoelectric driving device can be used for driving the robot.

(10) According to one aspect of the present invention, a method for driving a robot is provided. In this driving method, a first driving signal that fluctuates is applied to the first electrode, and a second driving signal that fluctuates is applied to the second electrode, thereby driving at least a part of the plurality of piezoelectric elements. Then, the plurality of link parts are rotated by the joint parts to drive the robot. According to this aspect, it is possible to change the rotation force of the robot by changing the amplitude of the voltage applied to the piezoelectric body without changing the voltage of the drive circuit.

(11) According to an aspect of the present invention, there is provided a driving method for the piezoelectric driving device according to the above aspect. In this driving method, a fluctuating first driving signal is applied to the first electrode, and a fluctuating second driving signal is applied to the second electrode. According to this embodiment, the amplitude of the voltage applied to the piezoelectric body can be increased or decreased as compared with the case where one electrode is grounded.

  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, a liquid feeding pump, and a medication pump.

The top view and sectional drawing which show schematic structure of a piezoelectric drive device. The top view of a diaphragm. Explanatory drawing which shows the electrical connection state of a piezoelectric drive device and a drive circuit. Explanatory drawing which shows the example of operation | movement of a piezoelectric drive device. FIG. 6 is an explanatory diagram illustrating an example of a drive circuit. The drive waveform of a comparative example. The graph which shows the voltage applied to the drive waveform and piezoelectric element of a 1st Example. The graph which shows the voltage applied to the drive waveform and piezoelectric element of a 2nd Example. The graph which shows the drive waveform of a 3rd Example, and the voltage applied to a piezoelectric element. The graph which shows the drive waveform of 4th Example, and the voltage applied to a piezoelectric element. The graph which shows the voltage applied to the drive waveform and piezoelectric element of a 5th Example. The graph which shows the drive waveform of 6th Example, and the voltage applied to a piezoelectric element. Explanatory drawing which shows a piezoelectric element and its drive signal typically. The graph which shows the voltage applied to a drive signal and a piezoelectric element. Explanatory drawing which shows the piezoelectric drive device of the modification of 1st Embodiment. The top view of the piezoelectric drive device of other embodiment. Explanatory drawing which shows an example of the robot using a piezoelectric drive device. Illustration of the wrist part of the robot Explanatory drawing which shows an example of the liquid feeding pump using a piezoelectric drive device.

  FIG. 1A is a plan view showing a schematic configuration of the piezoelectric driving device 10, and FIG. 1B is a cross-sectional view taken along the line BB. The piezoelectric driving device 10 includes a vibration plate 200 and two piezoelectric vibration members 100 arranged 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. 1A, 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. 1, 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. 1A) are configured by a laminated structure of the first electrode 130, the piezoelectric body 140, and the second electrodes 150a to 150e.

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. If the thickness of the piezoelectric body 140 is 20 μm or less, the piezoelectric driving device 10 can be sufficiently downsized.

  FIG. 2 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 attachment portion 230 is used for attaching the piezoelectric driving device 10 to another member with a screw 240. The diaphragm 200 can be formed of a metal material such as stainless steel, aluminum, an aluminum alloy, titanium, a titanium alloy, copper, a copper alloy, or an iron-nickel alloy, for example.

  The piezoelectric vibrating body 100 (FIG. 1) 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, for example, 3.5 mm or more and 30 mm or less, and the width W can be set in a range of, for example, 1 mm or more and 8 mm or less. 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, for example, 50 μm or more and 700 μm or less. If the thickness of the vibrating body portion 210 is 50 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” 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, Al ₂ O ₃ ).

  FIG. 3 is an explanatory diagram showing an electrical connection state between the piezoelectric driving device 10 and the driving circuit 300. Among the five second electrodes 150a to 150e, a pair of second electrodes 150a and 150d at the first diagonal are electrically connected to each other via the wiring 151, and another pair of second diagonals at the second diagonal are connected. The second electrodes 150b and 150c 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. Three second electrodes 150b, 150e, and 150d on the right side of FIG. 3 and the first electrode 130 (FIG. 1) are electrically connected to the drive circuit 300 via wirings 310, 312, 314, and 320. . The drive circuit 300 ultrasonically vibrates the piezoelectric drive device 10 by applying an alternating voltage that periodically changes between the pair of second electrodes 150 a and 150 d and the first electrode 130, thereby causing the protrusion 20 to vibrate. The contacting rotor (driven body) can be rotated in a predetermined rotation direction. Further, by applying an AC voltage between the other pair of second electrodes 150b and 150c and the first electrode 130, the rotor contacting the protrusion 20 can be rotated in the reverse direction. Such voltage application is performed simultaneously on the two piezoelectric vibrating bodies 100 provided on both surfaces of the diaphragm 200. Note that the wirings (or wiring layers and insulating layers) constituting the wirings 151, 152, 310, 312, 314, and 320 shown in FIG. 3 are not shown in FIG.

  FIG. 4 is an explanatory diagram illustrating an example of the operation of the piezoelectric driving device 10. The protrusion 20 of the piezoelectric driving device 10 is in contact with the outer periphery of the rotor 50 as a driven body. In the example shown in FIG. 4, the drive circuit 300 (FIG. 3) applies an AC voltage between the pair of second electrodes 150 a and 150 d and the first electrode 130, and the piezoelectric elements 110 a and 110 d are shown in FIG. 4. It expands and contracts in the direction of arrow x. In response to this, the vibrating body portion 210 of the piezoelectric driving device 10 is bent in the plane of the vibrating body portion 210 and deformed into a meandering shape (S-shape), and the tip of the protrusion 20 reciprocates in the direction of the arrow y. Or elliptical motion. As a result, the rotor 50 rotates around the center 51 in a predetermined direction z (clockwise direction in FIG. 4). The three connection portions 220 (FIG. 2) of the diaphragm 200 described with reference to FIG. 2 are provided at the positions of the vibration nodes (interferences) of the vibration body portion 210. Note that when the drive circuit 300 applies an AC voltage between the other pair of second electrodes 150b and 150c and the first electrode 130, the rotor 50 rotates in the reverse direction. If the same voltage as the pair of second electrodes 150a and 150d (or the other pair of second electrodes 150b and 150c) is applied to the center second electrode 150e, the piezoelectric driving device 10 expands and contracts in the longitudinal direction. The force applied to the rotor 50 from the protrusion 20 can be further increased. Such an operation of the piezoelectric driving device 10 (or the piezoelectric vibrating body 100) is described in the above-mentioned prior art document 1 (Japanese Patent Laid-Open No. 2004-320979 or corresponding US Pat. No. 7,224,102). The disclosure of which is incorporated by reference.

FIG. 5 is an explanatory diagram illustrating an example of a drive circuit. The drive circuit 300 includes a control circuit 330, a reference clock generation circuit 335, a waveform forming circuit 340, and amplification circuits 350 and 352. The reference clock generation circuit generates a clock signal Clk having a predetermined frequency (for example, several hundred kHz to several MHz). The waveform forming circuit 340 includes two frequency dividing circuits 342 and 344. The frequency dividing circuits 342 and 344 divide the clock signal Clk to generate digital signals DS1 and DS2 having a frequency lower than that of the clock signal Clk, respectively. The control circuit 330 controls the frequency and timing of the digital signals DS1 and DS2. That is, the control circuit 330 instructs the frequency dividing circuits 342 and 344 to control the number of times of frequency division from the clock signal Clk and the timing for starting frequency division. The amplifier circuit 350 is a class D amplifier, and generates an alternating voltage (also referred to as a drive signal Drv1) using the digital signal DS1. The amplifier circuit 352 is also a class D amplifier, and generates an alternating voltage (also referred to as a drive signal Drv2) using the digital signal DS2. The drive signals Drv1 and Drv2 are drive signals that periodically vary, and may be sine wave signals. When the drive signals Drv1 and Drv2 are sine waves, and the amplitudes of the drive signals are V1 and V2, the periods are T1 and T2, and the phases are α and β, the voltage at time t is expressed as follows.
Drv1: V1 × sin (2π × t / T1 + α) (1)
Drv2: V2 × sin (2π × t / T2 + β) (2)

  The control circuit 330 instructs the amplification circuits 350 and 352 on the amplification factor when generating the drive signals Drv1 and Drv2. The drive signal Drv1 is applied to the first electrode 130, and the drive signal Drv2 is applied to the second electrode 150. In the present embodiment, the digital signals DS1 and DS2 are generated using the two frequency dividing circuits 342 and 344. However, when the frequencies of the digital signals DS1 and DS2 are the same, a delay circuit is used instead of the frequency dividing circuit 344. May be used. The drive circuit 300 (control circuit 330) can control the periods of the drive signals Drv1 and Drv2 based on the number of frequency divisions from the clock signal Clk, can control the phases of the drive signals Drv1 and Drv2 based on the timing of the frequency division start, and can be amplified. Thus, the amplitudes of the drive signals Drv1 and Drv2 can be controlled.

  FIG. 6 is a graph showing the driving waveform and the voltage applied to the piezoelectric element of the comparative example, where the horizontal axis is time, the vertical axis is the relative value of the voltage, and the amplitude of the driving signal Drv2 is 1. The same applies to each embodiment described later. In the comparative example, the ground potential is applied to the first electrode 130 and the drive signal Drv2 is applied to the second electrode 150. In the comparative example, the voltage ΔV applied to the piezoelectric body 140 is equal to the voltage of the drive signal Drv2.

  FIG. 7 is a graph showing the driving waveform and the voltage applied to the piezoelectric element in the first embodiment. In the first embodiment and the following embodiments, the first drive signal Drv1 is applied to the first electrode 130, and the second drive signal Drv2 is applied to the second electrode 150. In the first embodiment, the two drive signals Drv1 and Drv2 have the same periods T1 and T2 and the same amplitudes V1 and V2, but the phases α and β are shifted by π. In the first example, as can be seen from the graph, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is twice that of the comparative example. According to the present embodiment, it is possible to apply a voltage twice that of the comparative example to the piezoelectric body 140 without increasing the drive voltage generated by the amplifier circuits 350 and 352 of the drive circuit 300.

  FIG. 8 is a graph showing the drive waveform and the voltage applied to the piezoelectric element in the second embodiment. In the second embodiment, the two drive signals Drv1 and Drv2 have the same periods T1 and T2, the same amplitudes V1 and V2, and the same phases α and β. In the second embodiment, as can be seen from the graph, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is zero. According to the present embodiment, the voltage applied to the piezoelectric body 140 can be made zero while generating periodic drive signals from the amplifier circuits 350 and 352 of the drive circuit 300.

  FIG. 9 is a graph showing the driving waveform and the voltage applied to the piezoelectric element of the third embodiment. In the third embodiment, the two drive signals Drv1 and Drv2 have the same periods T1 and T2 and the same amplitudes V1 and V2, but are shifted in phase by π / 12. In the third example, as can be seen from the graph, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is about half that of the comparative example. According to the present embodiment, the drive circuit 300 can change the voltage applied to the piezoelectric body 140 without changing the drive voltage generated by the amplifier circuits 350 and 352. In the above description, the phase difference Δθ (= | α−β |) of the two drive signals Drv1 and Drv2 is π / 12. However, if the phase difference Δθ is changed, the voltage applied to the piezoelectric body 140 can be changed. . When the period and amplitude of the two drive signals Drv1 and Drv2 are the same and the phase difference is Δθ, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is | 2 × sin (−Δθ / 2) |. When the phase difference between the two drive signals Drv1 and Drv2 is 0, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is zero as described in the second embodiment. If the phase difference is less than π / 3, the amplitude of the voltage ΔV can be made smaller than the amplitude in the comparative example. If the phase difference is π / 3, the amplitude of the voltage ΔV can be the same as the amplitude in the comparative example. If the phase difference is larger than π / 3 and smaller than π, the amplitude of the voltage ΔV can be made larger than the amplitude in the comparative example. When the phase difference is π, the amplitude of the voltage ΔV can be doubled as compared with the comparative example as described in the first embodiment. The drive circuit 300 may determine the phase difference Δθ between the drive signals Drv1 and Drv2 from the amplitude of the voltage ΔV applied to the piezoelectric body 140. In addition, the drive circuit 300 may determine which of the phase of the drive signal Drv1 and the phase of Drv2 is first. The phase difference between the two drive signals Drv1 and Drv2 described above can be determined by the difference in timing of the frequency division start of the frequency dividing circuits 342 and 344 (FIG. 5).

  FIG. 10 is a graph showing the drive waveform and the voltage applied to the piezoelectric element of the fourth embodiment. In the fourth embodiment, the amplitude and phase of the two drive signals Drv1 and Drv2 are the same, but the cycle T2 of the second drive signal Drv2 is twice the cycle T1 of the first drive signal Drv1. In this embodiment, when the periods are different, the same phase means that the zero-cross point at the rising edge of the short-cycle drive signal (first drive signal Drv1 in this embodiment) is the longer-cycle drive signal ( In the present embodiment, the case where the second driving signal Drv2) coincides with the rising zero cross point is described. As can be seen from the graph, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is larger than that of the comparative example. Further, the cycle of the voltage ΔV applied to the piezoelectric body 140 is the same as the cycle T2 of the second drive signal Drv2. If the phase difference Δθ is provided in the two drive signals Drv1 and Drv2 so that the maximum values of the two drive signals Drv1 and Drv2 match (for example, when the cycle of the drive signal Drv2 is 2π, If the phase difference between the drive signals Drv1 and Drv2 is π / 4), the voltage ΔV applied to the piezoelectric body 140 can be doubled compared to the comparative example. Conversely, the drive circuit 300 may set the cycle T1 of the drive signal Drv1 to twice the cycle T2 of the drive signal Drv2. In this case, the period of the voltage ΔV applied to the piezoelectric body 140 is the same as the period T1 of the drive signal Drv1. Note that the period of the two drive signals Drv1 and Drv2 can be controlled by the number of frequency divisions of the frequency dividing circuits 342 and 344.

  FIG. 11 is a graph showing the drive waveform and the voltage applied to the piezoelectric element of the fifth embodiment. In the fifth embodiment, the amplitude and phase of the two drive signals Drv1 and Drv2 are the same, but the period T2 of the drive signal Drv2 is three times the period T1 of the drive signal Drv1. As can be seen from the graph, the amplitude of the voltage ΔV applied to the piezoelectric body 140 is larger than that of the comparative example. Further, the cycle of the voltage ΔV applied to the piezoelectric body 140 is the same as the cycle T2 of the drive signal Drv2. Thus, the cycle T2 of the drive signal Drv2 may be three times the cycle T1 of the drive signal Drv1. If the phase difference Δθ is provided in the two drive signals Drv1 and Drv2 so that the maximum values of the two drive signals Drv1 and Drv2 coincide (for example, when the cycle of the drive signal Drv2 is 2π, 2 If the phase difference between the two drive signals Drv1 and Drv2 is π / 6), the amplitude of the voltage ΔV applied to the piezoelectric body 140 can be double that of the comparative example. Note that the drive circuit 300 may set the cycle T1 of the drive signal Drv1 to three times the cycle T2 of the drive signal Drv2, as in the fourth embodiment. As can be seen from the fourth and fifth embodiments, the drive circuit 300 may set the cycle of one drive signal to an integral multiple of the cycle of the other drive signal. Further, the cycle of the two drive signals Drv1 and Drv2 may be a simple integer ratio. In this case, the period of the voltage ΔV applied to the piezoelectric body 140 is the period of the least common multiple of the periods T1 and T2 of the two drive signals Drv1 and Drv2.

  FIG. 12 is a graph showing the driving waveform and the voltage applied to the piezoelectric element in the sixth embodiment. In the sixth embodiment, the phases of the drive signals Drv1 and Drv2 are the same, but the amplitude V2 of the drive signal Drv2 is three times the amplitude V2 of the drive signal Drv1, and the period T2 of the drive signal Drv2 is the drive signal It is three times the period T1 of Drv1. Thus, not only the period T2 but also the amplitude of the drive signal Drv1 may be changed. The amplitudes of the drive signals Drv1 and Drv2 can be controlled by the amplification factors of the amplifier circuits 350 and 352 (FIG. 5). As can be seen from the first to sixth embodiments, in the drive circuit 300, the first drive signal Drv1 and the second drive signal Drv2 are different from each other in at least one of phase, amplitude, and period. May be allowed. Further, the drive circuit 300 includes the phase of the first drive signal Drv1, the amplitude V1 of the first drive signal Drv1, the period T1 of the first drive signal Drv1, the phase of the second drive signal Drv2, At least one of the amplitude V2 of the second drive signal Drv2 and the period T2 of the second drive signal Drv2 may be variably controlled. The voltage applied to the piezoelectric body 140 can be easily controlled. As in the sixth embodiment, the amplitude of the short cycle drive signal (Drv1 in the sixth embodiment) is smaller than the amplitude of the long cycle drive signal (Drv2 in the sixth embodiment). Contrary to the sixth embodiment, the amplitude of the short cycle drive signal (Drv1 in the sixth embodiment) is set to the amplitude of the long cycle drive signal (Drv2 in the sixth embodiment). It may be larger than the amplitude.

  FIG. 13 is an explanatory diagram schematically showing a case where a plurality of piezoelectric elements are driven. A first drive signal Drv1 to a fourth drive signal Drv4 are output from the drive circuit 300, and the first electrode 130, the second electrode 150b, and 150e are respectively connected via the wirings 320, 310, 312, and 314. , 150d. The voltage ΔVb applied to the first piezoelectric element 110b is Drv2-Drv1, and the voltage ΔVe applied to the second piezoelectric element 110e is Drv3-Drv1, and is applied to the third piezoelectric element 110d. The voltage ΔVd is Drv4-Drv1. As shown in FIG. 3, the first electrode 130 is one continuous conductor layer, the second electrode 150b and the second electrode 150c are connected by a wiring 152, and the second electrode 150d and the second electrode 150a. Are connected by the wiring 151, the piezoelectric element 110c is also driven when the first piezoelectric element 110b is driven, and the piezoelectric element 110a is also driven when the third piezoelectric element 110d is driven.

  FIG. 14 is a graph showing drive signals Drv1 to Drv4 and voltages ΔVb, ΔVe, and ΔVd applied to the piezoelectric elements. The drive circuit 300 (FIG. 13) makes the period and amplitude of the two drive signals Drv1 and Drv2 the same, and shifts the phase by π. As a result, as described in the first embodiment, a voltage ΔVb having an amplitude twice as large as that of the comparative example is applied to the piezoelectric element 110b. Further, the drive circuit 300 (FIG. 13) makes the period, phase, and amplitude of the three drive signals Drv1, Drv3, Drv4 the same. In this case, the amplitudes of the voltages ΔVe and ΔVd applied to the piezoelectric bodies 140 of the piezoelectric elements 110e and 110d are zero as described in the second embodiment. Therefore, the piezoelectric elements 100b and 100c are expanded and contracted, and the piezoelectric elements 100e, 100d, and 100a are not expanded and contracted. In the above description, the phases of the two drive signals Drv1 and Drv2 are shifted by π. However, as described in the third embodiment, the phase difference Δθ between the two drive signals Drv1 and Drv2 can be any value between 0 and π. It may be. In this case, the amplitude of the voltage ΔVb applied to the piezoelectric element 110b is determined by the phase difference Δθ. Further, as described in the fourth to sixth embodiments, the two drive signals Drv1 and Drv2 may be different in at least one of the period, the phase, and the amplitude.

  In the above description, the case where the piezoelectric element 100b is expanded and contracted and the piezoelectric elements 100e and 100d are not expanded and contracted is described. However, the piezoelectric element 100e can be expanded and contracted, and the piezoelectric elements 100b and 100d can not be expanded and contracted. In this case, the period, phase, and amplitude of the three drive signals Drv1, Drv2, and Drv4 may be the same, and at least one of the period, phase, and amplitude of the drive signals Drv1 and Drv3 may be different. Further, the two piezoelectric elements 100b and 100e can be expanded and contracted, and the piezoelectric element 100d can not be expanded and contracted. In this case, the period, phase, and amplitude of the drive signals Drv1, Drv4 are made the same, at least one of the period, phase, and amplitude of the drive signals Drv1, Drv2 is changed, and the period, phase, and phase of the drive signals Drv1, Drv3 are changed. At least one of the amplitudes may be different. Note that the period, phase, and amplitude of the drive signals Drv2, Drv3 may be the same or different. That is, a drive signal having the same period, phase, and amplitude is supplied between the two electrodes 130, 150 of the piezoelectric element that is not desired to be expanded and contracted. If a drive signal having at least one of the amplitudes is supplied, any piezoelectric element among the piezoelectric elements 100b, 100e, and 100d can be expanded and contracted, and the other piezoelectric elements can be prevented from expanding and contracting. In the present embodiment, it is not necessary to divide the first electrode 130 for each piezoelectric element, and only one wiring is connected to the first electrode 130.

-Other embodiments of the piezoelectric drive:
FIG. 15 is a cross-sectional view of a piezoelectric driving device 10a as another embodiment of the present invention and corresponds to FIG. 1B of the first embodiment. In the piezoelectric driving device 10a, 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. 1B, 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 device 10a can also achieve the same effect as that of the first embodiment.

  FIG. 16A is a plan view of a piezoelectric driving device 10b as still another embodiment of the present invention, and corresponds to FIG. 1A of the first embodiment. 16A to 16C, for convenience of illustration, the connection part 220 and the attachment part 230 of the diaphragm 200 are not shown. In the piezoelectric driving device 10b of FIG. 16A, the pair of second electrodes 150b and 150c are omitted. The piezoelectric driving device 10b can also rotate the rotor 50 in one direction z as shown in FIG. Since the same voltage is applied to the three second electrodes 150a, 150e, and 150d in FIG. 16A, these three second electrodes 150a, 150e, and 150d are formed as one continuous electrode layer. May be.

  FIG. 16B is a plan view of a piezoelectric driving device 10c as still another embodiment of the present invention. In the piezoelectric driving device 10c, the second electrode 150e at the center in FIG. 1A is omitted, and the other four second electrodes 150a, 150b, 150c, and 150d have a larger area than that in FIG. Is formed. This piezoelectric drive device 10c can also achieve substantially the same effect as in the first embodiment.

  FIG. 16C is a plan view of a piezoelectric driving device 10d as still another embodiment of the present invention. In the piezoelectric driving device 10d, the four second electrodes 150a, 150b, 150c, and 150d in FIG. 1A are omitted, and one second electrode 150e is formed with a large area. The piezoelectric driving device 10d only expands and contracts in the longitudinal direction, but can apply a large force from the protrusion 20 to the driven body (not shown).

  As can be understood from FIG. 1 and FIGS. 16A to 16C, at least one electrode layer can be provided as the second electrode 150 of the piezoelectric vibrating body 100. However, if the second electrode 150 is provided at the diagonal position of the rectangular piezoelectric vibrator 100 as in the embodiment shown in FIGS. 1 and 16A and 16B, the piezoelectric vibrator 100 and The diaphragm 200 is preferable in that it can be deformed into a meandering shape that bends in the plane.

-Embodiments of a device using a piezoelectric drive:
The piezoelectric drive device 10 described above can apply a large force to the driven body by utilizing resonance, and can be applied to various devices. Examples of the piezoelectric driving device include a robot (including an electronic component conveying device (IC handler)), a dosing pump, a calendar feeding device for a clock, and a printing device (for example, a paper feeding mechanism. However, in a piezoelectric driving device used for a head, It is not applicable to the head because the diaphragm is not resonated.) And can be used as a driving device in various devices. Hereinafter, representative embodiments will be described.

  FIG. 17 is an explanatory view showing an example of a robot 2050 using the piezoelectric driving device 10 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 portion 2020 includes the above-described piezoelectric drive device 10, and the joint portion 2020 can be rotated or bent by an arbitrary angle using the piezoelectric drive device 10. 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 device 10, and the piezoelectric driving device 10 can be used to open and close the gripping unit 2003 to grip an object. The piezoelectric drive device 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 device 10.

  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 rotation unit 2022 includes the piezoelectric driving device 10, and the piezoelectric driving device 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 grip portion 2003 can be moved in the robot hand 2000, and the piezoelectric driving device 10 is mounted on the base portion of the grip portion 2003. For this reason, by operating the piezoelectric driving device 10, it is possible to move the gripping part 2003 and grip the object.

  The robot is not limited to a single-arm robot, and the piezoelectric driving device 10 can be applied to a multi-arm robot having two or more arms. Here, inside the wrist joint 2020 and the robot hand 2000, in addition to the piezoelectric driving device 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 device 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 portion 2020 (particularly, the joint portion at the tip of the arm 2010) or the robot hand 2000. Wiring can be arranged even in such a small space.

  FIG. 18 is an explanatory diagram showing an example of a liquid feed pump 2200 using the above-described piezoelectric driving device 10. The liquid feed pump 2200 includes a reservoir 2211, a tube 2212, the piezoelectric driving device 10, a rotor 2222, a deceleration transmission mechanism 2223, a cam 2202, a plurality of fingers 2213, 2214, 2215, 2216, and a case 2230. 2217, 2218, and 2219 are provided. 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 driving device 10 is provided in a state of being pressed against the side surface of the rotor 2222, and the piezoelectric driving device 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 driving device 10 according to the above-described embodiment, the driving current is smaller than that of the conventional piezoelectric driving 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.

・ Modification:
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.

・ Modification 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 130 and the piezoelectric material are formed on the vibration plate 200. The body 140 and the second electrode 150 may be formed.

Modification 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.

  In each of the above embodiments, the piezoelectric element using 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.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 10, 10a, 10b, 10c, 10d ... Piezoelectric drive device 12 ... Tube 20 ... Protrusion part (contact part, action part)
50 ... Rotor (driven body)
51 ... Center of driven body 100 ... Piezoelectric vibrator 110a, 110b, 11c, 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 210 ... vibrating body portion 220 ... connecting portion 230 ... mounting portion 240 ... screw 300 ... drive circuit 310, 312, 314, 320 ... wiring 330 ... control circuit 335 ... reference Clock generation circuit 340... Waveform formation circuit 340
342, 344 ... Frequency divider 350, 352 ... Amplifier circuit 2000 ... Robot hand 2003 ... Grasping 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

Claims (11)

A diaphragm,
A first piezoelectric element and a second piezoelectric element which are piezoelectric elements provided on the diaphragm;
A drive circuit for driving the first piezoelectric element and the second piezoelectric element ;
With
The first piezoelectric element includes a first electrode, a second electrode, and a piezoelectric body disposed between the first electrode and the second electrode,
The second piezoelectric element is
A third electrode forming one continuous conductor layer with the first electrode of the first piezoelectric element;
A fourth electrode separated from the second electrode of the first piezoelectric element;
Have
Wherein the driving circuit, said at least one of the first electrode and the third electrode, wherein said fourth electrode of the second piezoelectric element, applying a first drive signal varies, the first Applying a varying second drive signal to the second electrode of the piezoelectric element ;
The first drive signal and the second drive signal fluctuate periodically,
The first driving signal and the second driving signal, and phase and amplitude, and period, that have at least one different among the piezoelectric drive device. The piezoelectric drive device according to claim 1 ,
The drive circuit includes a phase of the first drive signal, an amplitude of the first drive signal, a cycle of the first drive signal, a phase of the second drive signal, and the second drive. A piezoelectric drive device that variably controls at least one of a signal amplitude and a cycle of the second drive signal. A diaphragm,
A first piezoelectric element and a second piezoelectric element which are piezoelectric elements provided on the diaphragm ;
A drive circuit for driving the first piezoelectric element and the second piezoelectric element ;
With
The first piezoelectric element includes a first electrode, a second electrode, and a piezoelectric body disposed between the first electrode and the second electrode,
The second piezoelectric element is
A third electrode forming one continuous conductor layer with the first electrode of the first piezoelectric element;
A fourth electrode separated from the second electrode of the first piezoelectric element;
Have
Wherein the driving circuit, said at least one of the first electrode and the third electrode, wherein said fourth electrode of the second piezoelectric element, applying a first drive signal varies, the first Applying a varying second drive signal to the second electrode of the piezoelectric element ;
The first drive signal and the second drive signal fluctuate periodically,
The phase of the first drive signal, the amplitude of the first drive signal, the period of the first drive signal, the phase of the second drive signal, and the amplitude of the second drive signal, A piezoelectric drive device that variably controls at least one of the period of the second drive signal . In the piezoelectric drive device according to any one of claims 1 to 3 ,
The drive circuit is a piezoelectric drive device in which a cycle of the first drive signal is the same as a cycle of the second drive signal. In the piezoelectric drive device according to any one of claims 1 to 4 ,
The piezoelectric drive device, wherein the drive circuit shifts the phase of the first drive signal with respect to the phase of the second drive signal. A diaphragm,
A first piezoelectric element that is a piezoelectric element provided on the diaphragm;
A drive circuit for driving the first piezoelectric element;
With
The first piezoelectric element includes a first electrode, a second electrode, and a piezoelectric body disposed between the first electrode and the second electrode,
The drive circuit applies a first drive signal that fluctuates to the first electrode, and applies a second drive signal that fluctuates to the second electrode,
The first drive signal and the second drive signal fluctuate periodically,
The piezoelectric drive device , wherein the drive circuit sets the cycle of the first drive signal to N times (N is an integer of 2 or more) or 1 / N of the cycle of the second drive signal . The piezoelectric drive device according to claim 6 .
The piezoelectric drive device, wherein the first drive signal and the second drive signal are different in at least one of phase, amplitude, and period. The piezoelectric drive device according to claim 6 or 7 ,
The drive circuit includes a phase of the first drive signal, an amplitude of the first drive signal, a cycle of the first drive signal, a phase of the second drive signal, and the second drive. A piezoelectric drive device that variably controls at least one of a signal amplitude and a cycle of the second drive signal. A plurality of link portions and a joint portion connecting the plurality of link portions;
The piezoelectric drive device according to any one of claims 1 to 8, wherein the plurality of link portions are rotated by the joint portions;
Robot equipped with. A robot driving method according to claim 9,
By applying each of the second drive signal in which the first driving signal and varies to fluctuate the corresponding electrode of the piezoelectric element to drive the front Ki圧 Denmoto child,
A robot driving method in which the plurality of link parts are rotated by the joint parts to drive the robot. A driving method of a piezoelectric driving device for driving the piezoelectric driving device according to any one of claims 1 to 8,
Respectively applying the second drive signal in which the first driving signal and varies to fluctuate the corresponding electrode of the piezoelectric element, the driving method of the piezoelectric drive device.

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