JP6442913B2 - Piezoelectric drive device, robot, and drive method thereof - Google Patents

Description

  The present invention relates to a piezoelectric drive device and various devices such as a robot including the piezoelectric drive device.

  Conventionally, a piezoelectric actuator (piezoelectric driving device) using a piezoelectric element is known (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.

  Conventionally, the frequency of the AC voltage to be applied (hereinafter also referred to as “drive frequency”) is set to a frequency close to the mechanical resonance frequency of the piezoelectric drive device, and the reciprocating motion or elliptical motion of the piezoelectric drive device is efficiently performed. To be done.

JP 2004-320979 A

  However, since the mechanical resonance frequency of the piezoelectric drive device changes depending on the operating conditions (disturbances) such as temperature conditions and load conditions, even if the same AC voltage is applied, the displacement of the reciprocating motion or elliptical motion of the piezoelectric drive device The amount changes, and the mechanical driving state by the piezoelectric driving device changes. For this reason, there exists a subject that it is difficult to maintain the mechanical drive state by a piezoelectric drive device in the substantially same state. The “mechanical driving state” means an operating state of the driven body when the piezoelectric driving device operates the driven body (for example, the rotor).

  Simply, it is possible to feed back the change in the mechanical resonance frequency of the piezoelectric drive device to change the drive frequency, but it is difficult to detect the change in the mechanical resonance frequency of the piezoelectric drive device. . For this reason, there has been a demand for a technique that can maintain the mechanical drive state of the piezoelectric drive device in substantially the same state even when the mechanical resonance frequency of the piezoelectric drive device changes.

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.
A piezoelectric driving device according to one aspect of the present invention includes: a piezoelectric body; an electrode provided on the piezoelectric body; a piezoelectric element having the piezoelectric body; The drive circuit drives the piezoelectric element so that the drive current value of the piezoelectric element approaches a target current value that is a drive current value corresponding to a drive frequency set when the piezoelectric element has standard characteristics. Feedback control is performed using the current as a control amount and the drive voltage as an operation amount.
According to the piezoelectric drive device of this aspect, the piezoelectric element is arranged such that the drive current value of the piezoelectric element approaches the target current value that is the drive current value corresponding to the drive frequency set when the piezoelectric element has standard characteristics. It is possible to execute feedback control using the drive current as the control amount and the drive voltage as the operation amount. As a result, even if the mechanical resonance frequency of the piezoelectric drive device changes as described in the problem, it is possible to prevent the mechanical drive state of the piezoelectric drive device from changing.
In addition, the present invention can be realized as the following forms.

(1) According to an aspect of the present invention, there is provided a piezoelectric driving device including a piezoelectric body, an electrode provided on the piezoelectric body, a piezoelectric element having the piezoelectric body, and a driving circuit that applies a driving voltage to the electrode. Is done. The drive circuit controls the drive voltage based on a drive current value of the piezoelectric element.
According to this piezoelectric drive device, even if the mechanical resonance frequency of the piezoelectric drive device changes as described in the subject by controlling the drive voltage based on the drive current value of the piezoelectric element, the piezoelectric drive device It is possible to prevent the mechanical drive state from changing.

(2) In the piezoelectric drive device, the drive circuit may perform feedback control using the drive current of the piezoelectric element as a control amount and the drive voltage as an operation amount.
According to this piezoelectric driving device, the mechanical resonance frequency of the piezoelectric driving device can be reduced as described in the problem by executing feedback control using the driving current value of the piezoelectric element as a control amount and the driving voltage as an operation amount. Even if it changes, it becomes possible to maintain the mechanical drive state by the piezoelectric drive device in substantially the same state.

(3) In the piezoelectric drive device, the drive circuit may execute upper limit control so that the drive voltage or drive power does not exceed a preset upper limit.
According to this configuration, damage to the piezoelectric element can be suppressed.

(4) In the piezoelectric driving device, the piezoelectric body may have a thickness of 0.05 μm or more and 20 μm or less.
According to this configuration, when the mechanical resonance frequency of the piezoelectric driving device changes compared to the case where the thickness of the piezoelectric body exceeds 20 μm, the mechanical driving state by the piezoelectric driving device is maintained in substantially the same state. The effect is remarkable.

(5) The piezoelectric driving device includes a diaphragm having a first surface and a second surface, and a piezoelectric vibrating body including the piezoelectric element, wherein the piezoelectric vibrating body includes the first surface of the vibrating plate and It may be arranged on at least one of the second surfaces.
According to this configuration, force can be generated by the vibration of the diaphragm and the piezoelectric vibrating body.

(6) In the piezoelectric driving device, the piezoelectric vibrating body may be disposed on the first surface and the second surface of the diaphragm.
According to this configuration, since the piezoelectric vibrating bodies are arranged on both the first surface and the second surface of the diaphragm, the driving force of the piezoelectric driving device can be increased.

(7) The piezoelectric driving device may include a protrusion provided on the diaphragm and capable of contacting the driven body.
According to this configuration, the driven body can be operated using the protrusion.

(8) In the piezoelectric driving device, the electrode may include a first electrode and a second electrode, and the piezoelectric body may be located between the first electrode and the second electrode. .

  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 view showing the schematic structure of the piezoelectric drive device of one embodiment. 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. It is explanatory drawing which shows the internal structure of a drive circuit. It is explanatory drawing shown about the feedback control of the drive current in a drive voltage generation circuit. Sectional drawing of the piezoelectric drive device of other 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. It is explanatory drawing of the wrist part of a robot. Explanatory drawing which shows an example of the liquid feeding pump using a piezoelectric drive device.

A. Embodiment:
FIG. 1A is a plan view showing a schematic configuration of a piezoelectric driving device 10 according to an embodiment of the present invention, and FIG. 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 of the piezoelectric driving device 10, a pair of diagonal second electrodes 150a and 150d are electrically connected to each other via the wiring 151, and another diagonal pair of first electrodes The two 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 or a pulsating voltage that periodically changes between the pair of second electrodes 150a and 150d and the first electrode 130, It is possible to rotate the rotor (driven body) in contact with the protrusion 20 in a predetermined rotation direction. 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. In addition, by applying an AC voltage or a pulsating current voltage between the other pair of second electrodes 150b and 150c and the first electrode 130, it is possible to rotate the rotor in contact with the protrusion 20 in the reverse direction. is there. Such application of voltage is simultaneously performed 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 or a pulsating voltage between the pair of second electrodes 150a and 150d and the first electrode 130, and the piezoelectric elements 110a and 110d. Expands and contracts in the direction of arrow x in FIG. 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. When the drive circuit 300 applies an AC voltage or a pulsating 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 showing the internal configuration of the drive circuit 300. Here, it is explanatory drawing which shows the circuit structure which applies an alternating voltage or a pulsating voltage to a pair of piezoelectric element 110a, 110d of the piezoelectric drive devices 10. FIG. Although not shown and described, the circuit configuration for applying an alternating voltage or a pulsating voltage to the other pair of piezoelectric elements 110b and 110c and the central piezoelectric element 110e of the piezoelectric driving device 10 is also the same.

  The drive circuit 300 includes a drive voltage generation circuit 340 and a monitor circuit 350. The drive voltage generation circuit 340 generates, as a drive voltage, an alternating voltage or a pulsating voltage that fluctuates between a positive side and a negative side with respect to a certain level of DC voltage equal to or higher than the ground potential. The generated drive voltage is applied to the piezoelectric elements 110a and 110d via the wirings 314 and 320. The frequency of the drive voltage (hereinafter also referred to as “drive frequency”) is preferably set to a frequency close to the mechanical resonance frequency of the piezoelectric drive device 10. This drive frequency will be described later. The monitor circuit 350 is a current monitor 352 that detects the current value of the drive current Ip that flows through the piezoelectric elements 110a and 110d, and a drive that is applied between the second electrodes 150a and 150d and the first electrode 130 from the drive voltage generation circuit 340. And a voltage monitor 354 for detecting a voltage value of the voltage Vp. The detected drive current value Ip and drive voltage value Vp are supplied to the drive voltage generation circuit 340. As described below, the drive voltage generation circuit 340 performs feedback control using the drive current value Ip as a control amount and the drive voltage Vp as an operation amount. The drive voltage generation circuit 340 preferably limits the generated drive voltage Vp based on the drive voltage value Vp, as will be described below.

  FIG. 6 is an explanatory diagram showing drive current feedback control in the drive voltage generation circuit 340. FIG. 6 is a graph conceptually showing the relationship between the frequency (drive frequency) fp of the drive voltage Vp, the impedance Z of the pair of piezoelectric elements 110a and 110d, and the drive current Ip.

  The piezoelectric driving device 10 has a resonance frequency fr1 of mechanical vibration in the longitudinal direction (referred to as “longitudinal primary vibration”) and a meandering mechanical vibration in the lateral direction (referred to as “flexed secondary vibration”). Resonance frequency fr2. Hereinafter, the resonance frequency of the longitudinal primary vibration is also simply referred to as “longitudinal resonance frequency”, and the resonance frequency of the bending secondary vibration is also simply referred to as “lateral resonance frequency” or “flexural resonance frequency”. Further, when the longitudinal resonance frequency and the bending resonance frequency are not particularly distinguished or collectively shown, they are also simply referred to as “resonance frequency”.

  A solid line in FIG. 6 indicates characteristics in a standard use environment. In general, the impedance Z of the pair of piezoelectric elements 110a and 110d takes a minimum value at the mechanical resonance frequencies fr1 and fr2, and the impedance Z increases as the frequency deviates from the resonance frequencies fr1 and fr2. 6). Further, the value of the drive current Ip changes according to the change of the impedance Z. That is, the value of the drive current Ip increases as the value of the impedance Z decreases, and the value of the drive current Ip decreases as the value of the impedance Z increases (lower stage in FIG. 6).

  Therefore, the drive displacement amount (mechanical displacement) of the piezoelectric drive device 10 is usually set by setting the drive frequency fp of the piezoelectric drive device 10 to the same frequency as the mechanical resonance frequencies fr1 and fr2 or a frequency close thereto. The amount is increased. However, as described above, since there are two mechanical resonance frequencies, the longitudinal resonance frequency fr1 and the bending resonance vibration frequency fr2, the frequency fts between them is set as the drive frequency fp, and the longitudinal primary frequency Driving characteristics of both vibration and bending secondary vibration can be obtained efficiently. The drive voltage Vp is set to a predetermined set voltage value Vts in the initial state. Of course, the drive frequency fp may be set to one of the resonance frequencies. Hereinafter, the frequency fts between the longitudinal resonance frequency fr1 and the bending resonance vibration frequency fr2 is also referred to as “set drive frequency fts”.

  Here, as described in the prior art, the mechanical resonance frequencies fr1 and fr2 of the piezoelectric driving device 10 change depending on various operating conditions (disturbances) such as a temperature condition and a load condition. Characteristics and drive current characteristics change. In particular, as in the piezoelectric driving device 10 of the present embodiment (FIG. 1), a piezoelectric driving device using a piezoelectric element having a thin film structure in which the thickness of the piezoelectric body 140 is less than 100 μm (particularly 0.05 μm to 20 μm). In some cases, the mechanical resonance frequency is easily affected by the change in the operating condition and is likely to change.

  The dashed-dotted line in FIG. 6 shows the impedance characteristic and the drive current force characteristic when the resonance frequency is shifted to a higher frequency than in a standard use environment. The impedance Z corresponding to the set drive frequency fts in this case changes to an impedance value Z1 higher than the impedance value Zts in the standard characteristics, and accordingly, the drive current Ip is greater than the set drive current value Its in the standard characteristics. It changes to a low current value I1. For this reason, the driving displacement amount (mechanical displacement amount) of the piezoelectric driving device 10 is reduced as compared with the standard characteristic state, that is, the state where the resonance frequency is not shifted.

  Therefore, the drive voltage generation circuit 340 uses the set drive current value Its as the target drive current value, and performs feedback control so that the drive current value Ip detected by the current monitor 352 approaches the target drive current value Its, thereby setting the drive voltage Vp. Occur. For example, as shown in FIG. 6, when the drive current value Ip is a current value I1 lower than the target drive current value Its, the voltage value of the drive voltage Vp so that the drive current value Ip approaches the target drive current value Its. To increase. On the contrary, when the drive current value Ip is larger than the target drive current value Its, the voltage value of the drive voltage Vp is lowered so that the drive current value Ip approaches the target drive current value Its.

  However, if the voltage value of the drive voltage Vp becomes excessively large, the piezoelectric elements 110a and 110d may be damaged. Therefore, it is preferable that the drive voltage generation circuit 340 performs control so that the drive voltage value Vp does not exceed a predetermined upper limit value Vu.

  Further, if the voltage value of the drive voltage Vp is excessively small, the piezoelectric elements 110a and 110d may not be displaced with a sufficient size. Therefore, it is preferable that the drive voltage generation circuit 340 controls the drive voltage value Vp so that it does not fall below the lower limit value Vd of the voltage that the piezoelectric element 110 can drive. However, both or one of the upper limit control and the lower limit control of the drive voltage Vp may be omitted.

  As described above, the drive circuit 300 of the piezoelectric drive device 10 of the present embodiment is configured so that the mechanical displacement amount by the piezoelectric drive device 10 is constant even if the mechanical resonance frequency of the piezoelectric drive device 10 changes. Can be driven. As a result, the driving state of the driven body when the piezoelectric driving apparatus 10 drives the driven body (for example, the rotor) is maintained substantially the same even if the mechanical resonance frequency of the piezoelectric driving apparatus 10 changes. Is possible.

B. Other embodiments of the piezoelectric drive:
FIG. 7 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. 7, as in FIG. 1B, wiring (or a wiring layer and an insulating layer) for electrical connection between the second electrodes 150a to 150e, 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. 8A 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. 8A to 8C, 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 in FIG. 8A, 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. 8A, these three second electrodes 150a, 150e, and 150d are formed as one continuous electrode layer. May be.

  FIG. 8B 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. 8C 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. 8A to 8C, 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 8A and 8B, 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.

C. 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. The piezoelectric driving device 10 is, for example, 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, a piezoelectric driving device used for a head. Then, since the diaphragm is not resonated, it cannot be applied to the head. Hereinafter, representative embodiments will be described.

  FIG. 9 is an explanatory diagram 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. 10 is an explanatory diagram of the 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 grips 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 compared to 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 a robot hand. Wiring can be arranged even in a small space such as 2000.

  FIG. 11 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.

D. Variation:
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) 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.

(2) 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.

(3) Modification 3:
In the above embodiment, the configuration in which the drive voltage value Vp is controlled so as not to exceed the predetermined upper limit value Vu has been described as an example. However, the drive power represented by the product of the drive current Ip and the drive voltage Vp is You may make it control so that the defined upper limit may not be exceeded.

(4) Modification 4:
In the above embodiment, the piezoelectric driving device 10 using the thin film piezoelectric body 140 formed by the film forming process has been described as an example. However, the driving circuit for driving the piezoelectric driving device using the so-called bulk piezoelectric body is also used. Applicable. In a piezoelectric drive device using a so-called bulk piezoelectric body, even if the mechanical resonance frequency of the piezoelectric drive device changes, it can be driven so that the mechanical displacement amount by the piezoelectric drive device becomes constant, Even if the mechanical resonance frequency of the piezoelectric driving device changes, the mechanical driving state by the piezoelectric driving device can be easily maintained in the same state. The “bulk piezoelectric body” means a piezoelectric body having a thickness of 100 μm or more. However, since the piezoelectric drive device 10 using the thin film-like piezoelectric body 140 of the above embodiment is more affected by the change in mechanical resonance frequency, the bulk-like thin film-like piezoelectric body 140 of the embodiment is used. The piezoelectric drive device 10 is more effective.

  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 ... Piezoelectric drive device 20 ... Projection part 50 ... Rotor 51 ... Center 100 ... Piezoelectric vibrating body 110 ... Piezoelectric element 120 ... Substrate 130 ... First electrode 140 ... Piezoelectric body 150 ... Second electrode 151, 152 ... Wiring 200 ... Diaphragm 211 ... first surface 212 ... second surface 210 ... vibrating body portion 220 ... connecting portion 230 ... mounting portion 240 ... screw 300 ... driving circuit 310, 312, 314, 320 ... wiring 340 ... driving voltage generating circuit 350 ... monitor circuit 352 ... Current monitor 354 ... Voltage monitor 2000 ... Robot hand 2003 ... Holding part 2010 ... Arm 2012 ... Link part 2020 ... Joint part 2022 ... Wrist rotation part 2050 ... Robot 2200 ... Liquid feeding pump 2202 ... Cam 2202A ... Protrusion 2211 ... Reservoir 2212 ... Tube 2213 ... Finger 22 22 ... Rotor 2223 ... Deceleration transmission mechanism 2230 ... Case

Claims (10)

A piezoelectric body, an electrode provided on the piezoelectric body, a piezoelectric element having the piezoelectric body,
A drive circuit for applying a drive voltage to the electrodes;
With
The drive circuit drives the piezoelectric element so that the drive current value of the piezoelectric element approaches a target current value that is a drive current value corresponding to a drive frequency set when the piezoelectric element has standard characteristics. A piezoelectric drive device that performs feedback control using a current as a control amount and the drive voltage as an operation amount . The piezoelectric drive device according to claim 1 ,
The piezoelectric drive device, wherein the drive circuit performs upper limit control so that the drive voltage or drive power does not exceed a preset upper limit. In the piezoelectric drive device according to claim 1 or 2 ,
The piezoelectric driving device, wherein the piezoelectric body has a thickness of 0.05 μm or more and 20 μm or less. In the piezoelectric drive device according to any one of claims 1 to 3 ,
A diaphragm having a first surface and a second surface;
A piezoelectric vibrator including the piezoelectric element,
The piezoelectric vibrator is disposed on at least one of the first surface and the second surface of the diaphragm. The piezoelectric drive device according to claim 4 .
The piezoelectric vibrator is disposed on the first surface and the second surface of the diaphragm. In the piezoelectric drive device according to claim 4 or 5 ,
A piezoelectric driving device comprising a protrusion provided on the diaphragm and capable of contacting a driven body. In the piezoelectric drive device according to any one of claims 1 to 6 ,
The electrode includes a first electrode and a second electrode,
The piezoelectric driving device, wherein the piezoelectric body is located between the first electrode and the second electrode. 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 7, wherein the plurality of link portions are bent at the joint portions.
Robot equipped with. The robot driving method according to claim 8 , wherein the driving circuit of the piezoelectric driving device performs feedback control using the driving current value of the piezoelectric element as a control amount and the driving voltage as an operation amount . A robot driving method in which the plurality of link portions are rotated by the joint portions. A method for driving a piezoelectric driving device according to any one of claims 1 to 7 ,
A method for driving a piezoelectric drive device, wherein feedback control is performed using a drive current value of the piezoelectric element as a control amount and the drive voltage as an operation amount .

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