JP2017103954A - Piezoelectric driving device, motor, robot, and pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric driving device that can reduce the amount of change in resonance frequency of a vibrator part by specifying the spring constant of a contact member that is in contact with a driving target body.SOLUTION: There is provided a piezoelectric driving device comprising: a substrate including a stationary part and a vibrator part that is provided with a piezoelectric element and supported by the stationary part; and a contact member that is in contact with a driving target body and transmits the movement of the vibrator part to the driving target body, in which the contact member is provided on the vibrator part via an adhesive; a low spring constant area having a spring constant equal to or lower than an initial spring constant is provided between the vibrator part and the contact member; the low spring constant area includes the adhesive; the initial spring constant is a spring constant of a system in which a first virtual sphere of the same material and same volume as those of the contact member is pressed against a second virtual sphere of the same material and same volume as those of the driving target body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric drive device, a motor, a robot, and a pump.

  Piezoelectric actuators (piezoelectric driving devices) that drive a driven body by vibrating a vibrating body by a piezoelectric element are used in various fields because they do not require a magnet or a coil.

  In such a piezoelectric driving device, the driven body of the piezoelectric driving device is used for the purpose of preventing transient vibration, preventing wear of the contact portion between the ultrasonic vibrator and the driven body member, and improving power efficiency. It is described that a spring region is provided in the vicinity of the contact portion with (see Patent Documents 1 to 3, for example).

JP 2008-295234 A Japanese Patent Laid-Open No. 06-22565 Japanese Patent Laying-Open No. 2015-80329

  However, Patent Documents 1 to 3 only describe qualitatively that there is a spring region, and do not mention a specific spring constant of the spring region, a deformation amount of the contact member due to pressing, or the like. .

  One of the objects according to some aspects of the present invention is to specify a spring constant of a contact member that is in contact with a driven body, thereby reducing the amount of change in the resonance frequency of the vibrating body portion. Is to provide. Another object of some embodiments of the present invention is to provide a motor, a robot, or a pump including the piezoelectric driving device described above.

  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 aspects or application examples.

[Application Example 1]
One aspect of the piezoelectric drive device according to the present invention is:
A fixed portion, and a substrate having a vibrating body portion provided with a piezoelectric element and supported by the fixed portion;
A contact member that contacts the driven body and transmits the movement of the vibrating body portion to the driven body;
Including
The contact member is provided on the vibrating body part via an adhesive,
A low spring constant region having a spring constant equal to or less than an initial spring constant is provided between the vibrating body portion and the contact member,
The low spring constant region includes the adhesive,
The initial spring constant is a spring constant of a system in which a first phantom sphere having the same material and the same volume as the contact member is pressed against a second phantom sphere having the same material and the same volume as the driven body.

In such a piezoelectric driving device, even if the contact member is worn due to contact with the driven body or the contact state between the contact member and the driven body is changed due to a disturbance, the resonance frequency ( The amount of change in the resonance frequency of the longitudinal vibration) can be reduced (details will be described later).

[Application Example 2]
In application example 1,
The Young's modulus of the first phantom sphere is E ₁ , the Poisson's ratio is ν ₁ , the radius is R ₁ ,
The Young's modulus of the second phantom sphere is E ₂ , the Poisson's ratio is ν ₂ , the radius is R ₂ ,
When the radius of the contact surface between the first phantom sphere and the second phantom sphere when the first phantom sphere is pressed against the second phantom sphere with the pressing force F ₀ is a ₀ , the low spring constant The spring constant K of the region is
May be satisfied.
However,
It is.

  In such a piezoelectric drive device, the amount of change in the resonance frequency of the vibrating body portion can be reduced.

[Application Example 3]
In application example 1 or 2,
The low spring constant region may be the adhesive.

  In such a piezoelectric drive device, the amount of change in the resonance frequency of the vibrating body portion can be reduced.

[Application Example 4]
One aspect of the motor according to the present invention is:
The piezoelectric drive device according to any one of Application Examples 1 to 3,
A rotor rotated by the piezoelectric drive device;
including.

  Such a motor can include a piezoelectric drive according to the present invention.

[Application Example 5]
One aspect of the robot according to the present invention is:
A plurality of link parts;
A joint part connecting a plurality of the link parts;
The piezoelectric drive device according to any one of Application Examples 1 to 3, in which a plurality of the link portions are rotated at the joint portions,
including.

  Such a robot can include the piezoelectric driving device according to the present invention.

[Application Example 6]
One aspect of the pump according to the present invention is:
The piezoelectric drive device according to any one of Application Examples 1 to 3,
A tube that transports the liquid;
A plurality of fingers for closing the tube by driving the piezoelectric driving device;
including.

  Such a pump can include a piezoelectric drive according to the present invention.

The top view which shows typically the piezoelectric drive device which concerns on this embodiment. 1 is a cross-sectional view schematically showing a piezoelectric drive device according to an embodiment. The top view which shows typically the piezoelectric drive device which concerns on this embodiment. The figure for demonstrating the state which pressed the 1st virtual sphere against the 2nd virtual sphere. The figure which shows the equivalent circuit for demonstrating the piezoelectric drive device which concerns on this embodiment. The figure for demonstrating operation | movement of the piezoelectric drive device which concerns on this embodiment. The table | surface which shows the relationship between the radius of a contact surface, a load, a displacement, and an equivalent spring constant. The graph which shows the relationship between the radius of a contact surface, a load, a displacement, and an equivalent spring constant. The graph which shows the relationship between the drive time of a piezoelectric drive device, and the diameter of a contact surface. The graph which shows the relationship between the drive time of a piezoelectric drive device, and the difference of the resonant frequency of longitudinal vibration, and the resonant frequency of bending vibration. The graph which shows the relationship between a frequency and an impedance. The graph which shows the relationship between a frequency and an impedance. The figure for demonstrating the model used for simulation. The graph which shows the relationship between a spring constant and a resonant frequency. The table | surface which shows the variation | change_quantity of the change amount of a spring constant, and the resonance frequency of a longitudinal vibration. The table | surface which shows the relationship between a spring constant and the variation | change_quantity of a resonant frequency. A table showing the relationship between Young's modulus and thickness. The top view which shows typically the piezoelectric drive device which concerns on the 1st modification of this embodiment. The top view which shows typically the piezoelectric drive device which concerns on the 2nd modification of this embodiment. The figure for demonstrating the robot which concerns on this embodiment. The figure for demonstrating the wrist part of the robot which concerns on this embodiment. The figure for demonstrating the pump which concerns on this embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

1. Piezoelectric Drive Device First, a piezoelectric drive device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a plan view schematically showing a piezoelectric driving device 100 according to this embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 schematically showing the piezoelectric driving device 100 according to the present embodiment. FIG. 3 is an enlarged view of the vicinity of the contact member in FIG. 1.

  As shown in FIGS. 1 to 3, the piezoelectric driving device 100 includes a substrate 10, a contact member 20, a low spring constant region 22, and a piezoelectric element 30.

  The substrate 10 is composed of, for example, a stacked body of a silicon substrate, a silicon oxide layer provided on the silicon substrate, and a zirconium oxide layer provided on the silicon oxide layer.

  As shown in FIG. 1, the substrate 10 includes a vibrating body portion 12, a fixing portion 14, a first connection portion 16, and a second connection portion 18. In the illustrated example, the planar shape (the shape viewed from the thickness direction of the substrate 10) of the vibrating body portion 12 is a rectangle. A piezoelectric element 30 is provided on the vibrating body portion 12, and the vibrating body portion 12 can vibrate by deformation of the piezoelectric element 30. The fixing portion 14 supports the vibrating body portion 12 via the connection portions 16 and 18. For example, the fixing portion 14 is fixed to an external member (not shown). In the illustrated example, the connecting portions 16 and 18 extend from a central portion in the longitudinal direction of the vibrating body portion 12 in a direction orthogonal to the longitudinal direction and are connected to the fixing portion 14.

The contact member 20 is provided on the end portion 12 a in the longitudinal direction (hereinafter, also simply referred to as “longitudinal direction”) of the vibrating body portion 12 via the low spring constant region 22. The end portion 12 a is configured by the short side of the vibrating body portion 12 in plan view (as viewed from the thickness direction of the substrate 10). In the illustrated example, the shape of the contact member 20 is a rectangular parallelepiped. The contact member 20 is a member that contacts the driven member (specifically, the rotor 4 shown in FIG. 6 described later) and transmits the movement of the vibrating body portion 12 to the driven member. The material of the contact member 20 is, for example, ceramics (specifically, alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N), or a mixture thereof).

  The low spring constant region 22 is provided between the vibrating body portion 12 and the contact member 20. In the illustrated example, the shape of the low spring constant region 22 is a rectangular parallelepiped. The low spring constant region 22 includes an adhesive. In the illustrated example, the low spring constant region 22 is an adhesive. Specifically, the low spring constant region 22 is an elastic adhesive such as silicone, urethane, or epoxy.

The low spring constant region 22 has a spring constant equal to or less than the initial spring constant in the longitudinal direction. Here, the “initial spring constant” means that, as shown in FIG. 4, the first phantom sphere B ₁ having the same material and the same volume as the contact member 20 is replaced with the second phantom sphere having the same material and the same volume as the driven body. This is the spring constant of the system pressed against B ₂ (for details, see “3. Experimental example” described later).

Further, the Young's modulus of the first phantom sphere B ₁ is E ₁ , the Poisson's ratio is ν ₁ and the radius is R _1, and the Young's modulus of the second phantom sphere B ₂ is E ₂ , the Poisson's ratio is ν ₂ , and the radius is R ₂ is the radius of the contact surface C formed by deforming the phantom spheres B ₁ and B ₂ when the first phantom sphere B ₁ is pressed against the second phantom sphere B ₂ with the pressing force F ₀ . Assuming a ₀ , the spring constant K of the low spring constant region 22 satisfies the relationship of the following formula (1).

However, E *, _{a 0,} and R satisfy the relationship of formula (2) to (4).

  The piezoelectric element 30 is provided on the substrate 10 as shown in FIG. Specifically, the piezoelectric element 30 is provided on the vibrating body portion 12. The piezoelectric element 30 includes a first electrode 32, a piezoelectric layer 34, and a second electrode 36.

  The first electrode 32 is provided on the vibrating body portion 12. In the example illustrated in FIG. 1, the planar shape of the first electrode 32 is a rectangle. The first electrode 32 may be configured by an iridium layer provided on the vibrating body portion 12 and a platinum layer provided on the iridium layer. The thickness of the iridium layer is, for example, not less than 5 nm and not more than 100 nm. The thickness of the platinum layer is, for example, not less than 50 nm and not more than 300 nm. The first electrode 32 is a metal layer made of Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, Cu, or a mixture or stack of two or more of these. It may be a thing. The first electrode 32 is one electrode for applying a voltage to the piezoelectric layer 34.

  The piezoelectric layer 34 is provided on the first electrode 32. In the illustrated example, the planar shape of the piezoelectric layer 34 is a rectangle. The thickness of the piezoelectric layer 34 is, for example, not less than 50 nm and not more than 20 μm, and preferably not less than 1 μm and not more than 7 μm. Thus, the piezoelectric element 30 is a thin film piezoelectric element. If the thickness of the piezoelectric layer 34 is smaller than 50 nm, the output of the piezoelectric driving device 100 may be small. Specifically, when the voltage applied to the piezoelectric layer 34 is increased in order to increase the output, the piezoelectric layer 34 may cause dielectric breakdown. If the thickness of the piezoelectric layer 34 is greater than 20 μm, the piezoelectric layer 34 may crack.

As the piezoelectric layer 34, a perovskite oxide piezoelectric material is used. Specifically, the material of the piezoelectric layer 34 is, for example, lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT), lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O). ₃ : PZTN). The piezoelectric layer 34 can be deformed (stretched) when a voltage is applied by the electrodes 32 and 36.

  The second electrode 36 is provided on the piezoelectric layer 34. In the illustrated example, the planar shape of the second electrode 36 is a rectangle. The second electrode 36 may be configured by an adhesion layer provided on the piezoelectric layer 34 and a conductive layer provided on the adhesion layer. The thickness of the adhesion layer is, for example, 10 nm or more and 100 nm or less. The adhesion layer is, for example, a TiW layer, a Ti layer, a Cr layer, a NiCr layer, or a laminate thereof. The thickness of the conductive layer is, for example, 1 μm or more and 10 μm or less. The conductive layer is, for example, a Cu layer, an Au layer, an Al layer, or a laminate thereof. The second electrode 36 is the other electrode for applying a voltage to the piezoelectric layer 34.

A plurality of piezoelectric elements 30 are provided. In the example shown in FIG. 1, five piezoelectric elements 30 are provided (piezoelectric elements 30a, 30b, 30c, 30d, and 30e). In plan view, for example, the areas of the piezoelectric elements 30a to 30d are the same, and the piezoelectric element 30e is equivalent to the piezoelectric element 30a.
It has an area larger than ˜30d. The piezoelectric element 30 e is provided along the longitudinal direction of the vibrating body 12 at the central portion in the short direction of the vibrating body 12. The piezoelectric elements 30 a, 30 b, 30 c, and 30 d are provided at the four corners of the vibrating body portion 12. In the illustrated example, in the piezoelectric elements 30a to 30e, the first electrode 32 is provided as one continuous conductive layer.

  Although not shown, the piezoelectric driving device 100 is electrically connected to the insulating layer provided so as to cover the piezoelectric element 30, the first wiring layer electrically connected to the first electrode 32, and the second electrode 36. There may be a second wiring layer connected to each other.

  FIG. 5 is a diagram showing an equivalent circuit for explaining the piezoelectric driving device 100. The piezoelectric elements 30 are divided into three groups. The first group has two piezoelectric elements 30a and 30d. The second group has two piezoelectric elements 30b and 30c. The third group has only one piezoelectric element 30e. As shown in FIG. 5, the first group of piezoelectric elements 30 a and 30 d are connected in parallel to each other and connected to the drive circuit 110. The second group of piezoelectric elements 30 b and 30 c are connected in parallel to each other and connected to the drive circuit 110. The third group of piezoelectric elements 30e are connected to the drive circuit 110 independently.

  The drive circuit 110 has a period between predetermined electrodes of the five piezoelectric elements 30a, 30b, 30c, 30d, and 30e, for example, the first electrode 32 and the second electrode 36 of the piezoelectric elements 30a, 30d, and 30e. An alternating voltage or a pulsating voltage that changes with time is applied. Thereby, the piezoelectric driving device 100 can rotate the rotor (driven member) contacting the contact member 20 in a predetermined rotation direction by ultrasonically vibrating the vibrating body portion 12. 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) of the pulsating voltage is one direction from one electrode to the other electrode.

  The direction of the electric field is preferably from the second electrode 36 to the first electrode 32 rather than from the first electrode 32 to the second electrode 36. Further, by applying an AC voltage or a pulsating voltage between the electrodes 32 and 36 of the piezoelectric elements 30b, 30c and 30e, the rotor contacting the contact member 20 can be rotated in the reverse direction.

  FIG. 6 is a diagram for explaining the operation of the vibrating body portion 12 of the piezoelectric driving device 100. As shown in FIG. 6, the contact member 20 of the piezoelectric driving device 100 is in contact with the outer periphery of the rotor 4 as a driven member. The drive circuit 110 applies an alternating voltage or a pulsating voltage between the electrodes 32 and 36 of the piezoelectric elements 30a and 30d. Thereby, the piezoelectric elements 30a and 30d expand and contract in the direction of the arrow x. In response to this, the vibrating body portion 12 is bent and vibrated in the plane of the vibrating body portion 12 and deformed into a meandering shape (S-shape). Furthermore, the drive circuit 110 applies an alternating voltage or a pulsating voltage between the electrodes 32 and 36 of the piezoelectric element 30e. Thereby, the piezoelectric element 30e expands and contracts in the direction of the arrow y. Thereby, the vibrating body portion 12 vibrates longitudinally within the plane of the vibrating body portion 12. Due to the bending vibration and longitudinal vibration of the vibrating body 12 as described above, the contact member 20 moves elliptically as indicated by an arrow z. As a result, the rotor 4 rotates around the center 4a in a predetermined direction R (clockwise direction in the illustrated example).

  When the drive circuit 110 applies an AC voltage or a pulsating voltage between the electrodes 32 and 36 of the piezoelectric elements 30b, 30c, and 30e, the rotor 4 is in a direction opposite to the direction R (counterclockwise direction). Rotate to.

  Moreover, it is preferable that the resonance frequency of the bending vibration and the resonance frequency of the longitudinal vibration of the vibrating body 12 are the same. Thereby, the piezoelectric drive device 100 can rotate the rotor 4 efficiently.

  As shown in FIG. 6, the motor 120 according to the present embodiment includes the piezoelectric driving device (piezoelectric driving device 100 in the illustrated example) according to the present invention and the rotor 4 rotated by the piezoelectric driving device 100. The material of the rotor 4 is ceramics, for example. In the illustrated example, the rotor 4 has a cylindrical shape.

  The piezoelectric drive device 100 has the following features, for example.

  In the piezoelectric driving device 100, a low spring constant region 22 having a spring constant equal to or less than the initial spring constant is provided between the vibrating body portion 12 and the contact member 20. Therefore, in the piezoelectric driving device 100, even if the contact member 20 is worn due to contact with the rotor 4 or the contact state between the contact member 20 and the rotor 4 is changed due to a disturbance, the resonance frequency of the vibrating body portion 12. (See “3. Experimental example” described later for details). As a result, in the piezoelectric drive device 100, the output characteristics can be stabilized and the life can be extended.

2. Next, a method for manufacturing a piezoelectric drive device according to the present embodiment will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the first electrode 32 is formed on the vibrating body portion 12 of the substrate 10. The first electrode 32 is formed, for example, by sputtering, CVD (Chemical Vapor Deposition), vacuum deposition, or the like, and patterning (patterning by photolithography and etching).

Next, the piezoelectric layer 34 is formed on the first electrode 32. The piezoelectric layer 34 is formed, for example, by repeating the formation of a precursor layer by a liquid phase method and the crystallization of the precursor layer, followed by patterning. The liquid phase method is a method of forming a thin film material using a raw material liquid containing a constituent material of a thin film (piezoelectric layer), and specifically, a sol-gel method or MOD (Metal Organic).
Deposition) method and the like. Crystallization is performed by, for example, heat treatment at 700 ° C. to 800 ° C. in an oxygen atmosphere.

  Next, the second electrode 36 is formed on the piezoelectric layer 34. The second electrode 36 is formed by the same method as the first electrode 32, for example. Although not shown, the patterning of the second electrode 36 and the patterning of the piezoelectric layer 34 may be performed as the same process.

  Through the above steps, the piezoelectric element 30 can be formed on the vibrating body portion 12 of the substrate 10.

  Next, the contact member 20 is bonded to the vibrating body portion 12 through the low spring constant region 22 that is an adhesive.

  The piezoelectric driving device 100 can be manufactured through the above steps.

3. Experimental Example An experimental example is shown below to describe the present invention more specifically. The present invention is not limited by the following experimental examples.

3.1. Calculation of radius of contact surface and equivalent spring constant A first phantom sphere B ₁ and a second phantom sphere B ₂ made of alumina were assumed. First virtual sphere B ₁ represents, corresponds to the contact member, the second virtual sphere B ₂ corresponds to the rotor. The first phantom sphere B ₁ has a radius R ₁ of 1 × 10 ⁻⁴ m, a Young's modulus E ₁ of 3.7 × 10 ¹¹ Pa, and a Poisson's ratio ν ₁ of 0.23. The radius R ₂ of the second phantom sphere B ₂ was 1 × 10 ⁻² m, the Young's modulus E ₂ was 3.7 × 10 ¹¹ Pa, and the Poisson's ratio ν ₂ was 0.23.

It was assumed that the first phantom sphere B ₁ as described above was pressed against the second phantom sphere B ₂ with a pressing force F ₀ = 0.6 N (see FIG. 4). According to the equations (2) to (4), the radius of the contact surface C formed by deforming the phantom spheres B ₁ and B ₂ by being pressed with the converted Young's modulus E *, the converted radius R, and F ₀ ( the initial radius) a _0, was determined as follows. The shape of the contact surface C is a circle.

E * = 1.95 × 10 ¹¹ N / cm ²
R = 9.9 × 10 ⁻⁵ m
a ₀ = 6.1 × 10 ⁻⁶ m

Next, the radius a of the contact surface C is swung, and the load (force acting on the phantom spheres B ₁ and B ₂ ) F, displacement (first) according to the following formulas (5) to (7) based on the Hertzian stress theory. The sum of the deformation amount of the phantom sphere B _{1 and} the deformation amount of the second phantom sphere B ₂ ) and the equivalent spring constant K were obtained.

  FIG. 7 is a table showing the load F, displacement δ, and equivalent spring constant K when the radius a is swung. FIG. 8 is a graph showing the relationship between the radius a and the equivalent spring constant K.

7 and 8, it was found that the radius a of the contact surface C and the equivalent spring constant K are in a proportional relationship, and that the equivalent spring constant K increases as the radius a increases. As the load F is increased, the phantom spheres B ₁ and B ₂ are deformed and the area of the contact surface C is increased, so that the equivalent spring constant K is increased. Further, when the phantom spheres B ₁ and B ₂ are shaved and the area of the contact surface C increases, it can be said that the equivalent spring constant K increases.

7 and 8, the radius a = 6.1 × 10 ⁻⁶ m corresponds to the radius a ₀ and is the radius of the contact surface C immediately after the phantom spheres B ₁ and B ₂ are brought into contact with each other. Constant K = 1.6 × 10 ⁶ N / m is a spring constant of the system when the second phantom sphere B ₂ is pressed against the first phantom sphere B ₁ with a pressing force of 0.6 N (initial spring constant). It is.

3.2. Experiment on Change of Contact Surface Size and Resonant Frequency Next, an experiment was performed using a contact member made of alumina and a rotor. The contact member is pressed against the rotor with a load of 0.6 N to drive the piezoelectric drive device, the diameter Φ of the contact surface C between the contact member and the rotor, and the resonance frequency and bending of the longitudinal vibration in the vibrating body of the piezoelectric drive device A difference Δf from the resonance frequency of vibration was determined. A spherical body having a radius of 1 × 10 ⁻⁴ m was used as the contact member. A cylindrical body having a radius of 1 × 10 ⁻² m was used as the rotor. In addition, since the radius of the rotor is sufficiently larger than the radius of the contact member, the contact surface C between the contact member and the rotor can be regarded as formed by shaving (deforming) the contact member.

  FIG. 9 is a graph showing the relationship between the driving time of the piezoelectric driving device and the diameter Φ of the contact surface C. FIG. 10 is a graph showing the relationship between the driving time of the piezoelectric driving device and the difference Δf between the resonance frequency of the longitudinal vibration and the resonance frequency of the bending vibration.

  As shown in FIGS. 9 and 10, it was found that the contact member was shaved by the driving of the piezoelectric driving device, and the resonance frequency of the vibrating body portion was changed. With about 15 minutes of driving, the contact member was scraped until the diameter Φ of the contact surface C reached 36 μm, and the difference Δf in resonance frequency increased by 14 kHz immediately after the start of driving.

  11 and 12 are graphs showing the relationship between frequency and impedance. FIG. 11 shows a state immediately after the start of driving of the piezoelectric driving device (drive time zero), and FIG. 12 shows a state after about 15 minutes have elapsed.

  As shown in FIG. 11, immediately after the start of driving of the piezoelectric driving device, only one valley of the impedance curve was confirmed. This is because the resonance frequency of the longitudinal vibration of the vibrating body portion and the resonance frequency of the bending vibration are the same. On the other hand, as shown in FIG. 12, two valleys of the impedance curve were confirmed after about 15 minutes. This is because the resonance frequency of the longitudinal vibration of the vibrating body portion and the resonance frequency of the bending vibration are shifted. The laser Doppler vibrometer revealed that the valley with the lower frequency corresponds to bending vibration, and the valley with the higher frequency corresponds to longitudinal vibration. The resonance frequency of the bending vibration increased by about 10 kHz immediately after the start of driving. The resonance frequency of the longitudinal vibration increased by about 24 kHz immediately after the start of driving. The reason why the change in the resonance frequency of the bending vibration is smaller than the change in the resonance frequency of the longitudinal vibration is considered to be due to slippage between the contact member and the rotor in the bending direction (lateral direction).

3.3. Simulation concerning matching between calculation and experiment A simulation by a finite element method was performed using a model M as shown in FIG. In the simulation, the load F was applied to the model M to change the spring constant in the longitudinal direction of the model M, and the resonance frequency of the longitudinal vibration at that time was obtained.

  FIG. 14 is a graph showing the relationship between the spring constant in the longitudinal direction of the model M and the resonance frequency of the longitudinal vibration of the model M.

Here, according to the experiment of “3.2.” Described above, when the driving time is about 15 minutes, the diameter Φ of the contact surface C becomes 36 μm, and the longitudinal vibration may increase by about 24 kHz compared to immediately after the start of driving. all right. When the diameter Φ of the contact surface C is 36 μm (that is, the radius a is 18 μm), the equivalent spring constant is 4.6 × 10 ⁶ N / m according to the calculation of “3.1.” Described above (from FIG. 7). is there. In the experiment of “3.2.” Described above, since the load F is 0.6 N, the equivalent spring constant immediately after the start of driving is 1.6 × 10 ⁶ N / m. That is, when the equivalent spring constant is changed from 1.6 × 10 ⁶ N / m to 4.6 × 10 ⁶ N / m by the calculation of “3.1.” And the experiment of “3.2.” Described above, It can be said that the resonance frequency of the longitudinal vibration increases by about 24 kHz.

In the simulation result shown in FIG. 14, when the spring constant is changed from 1.6 × 10 ⁶ N / m to 4.6 × 10 ⁶ N / m, the resonance frequency of the longitudinal vibration is increased by about 30 kHz. The increase amount of the resonance frequency of the longitudinal vibration almost coincided with the value of about 24 kHz obtained in the experiment of “3.2.”. It can be said that when the contact member is scraped, the spring constant changes and the resonance frequency of the vibrating body portion changes.

  When the shape of the contact member is spherical or bowl-shaped (semi-cylindrical), the contact member is shaved due to wear and the contact area between the contact member and the rotor increases, so that the resonance frequency of the vibrating body portion changes. Even when the shape of the contact member is a rectangular parallelepiped or cylindrical system, the rotor hits the corner of the contact member due to assembly error or external shock, or the contact state between the contact member and the rotor changes due to the eccentricity or undulation of the rotor. During the driving of the piezoelectric driving device, the resonance frequency of the vibrating body portion changes.

3.4. Calculation on change in spring constant and resonance frequency in low spring constant region Next, assuming a piezoelectric drive device in which a low spring constant region is provided between the contact member and the vibrating body, a spring constant in the low spring constant region, The relationship between the change in the resonance frequency of the longitudinal vibration of the vibrating body portion was calculated. In a series connection system in which a low spring constant region is provided between the contact member and the vibrating body, the combined spring constant of the contact member and the low spring constant region is the spring constant of the low spring constant region having a low spring constant. Dependent.

FIG. 15 shows changes in the spring constant when a low spring constant region having a spring constant K _T = 1.6 × 10 ⁶ N / m is provided (when present) and when not present (when not present). It is a table | surface which shows the variation | change_quantity of the resonance frequency of quantity and longitudinal vibration.

In FIG. 15, in the case of “none”, “initial spring constant” corresponds to the spring constant K _S1 of the contact member immediately after driving the piezoelectric driving device, and “after spring constant change” indicates that the piezoelectric driving device is, for example, 15 This corresponds to the spring constant K _S2 of the contact member when driven for a minute. In the case of "Yes", "spring constant initial" corresponds to the synthetic spring constant K _G1 between the contact member and the low spring constant area was calculated by the following equation (8). In the case of "Yes", "after the spring constant variation" corresponds to the combined spring constant K _G2 between the contact member and the low spring constant area was calculated by the following equation (9).

In FIG. 15, in the case of “none”, 24 kHz of “longitudinal resonance frequency change amount” is a value obtained by the above-described experiment of “3.2.”. In the case of “present”, the value ΔF _T (= 3.097 kHz) of the “longitudinal resonance frequency change amount” has a proportional relationship between the spring constant and the resonance frequency as shown in FIG. The change amount of the spring constant in the case of is ΔK _S (= 3 × 10 ⁶ N / m), the change amount of the longitudinal resonance frequency in the case of “None” is ΔF _S (= 24 kHz), and the spring constant in the case of “Yes” The amount of change was calculated from the following formula (10) as ΔK _T (= 3.9 × 10 ⁵ N / m).

As shown in FIG. 15, by providing a low spring constant region with a spring constant K _T = 1.6 × 10 ⁶ N / m, the amount of change in the resonance frequency of the longitudinal vibration of the vibrating body portion can be reduced. It was found that it was suppressed to about 1/8 compared with the case where it was not provided. Here, “1.6 × 10 ⁶ N / m spring constant” indicates that the first phantom sphere B ₁ is pushed against the second phantom sphere B ₂ as shown in the calculation of “3.1.” Above. This is the spring constant when applied (initial spring constant). Therefore, by providing a low spring constant having a spring constant equal to or less than the initial spring constant in the longitudinal direction between the vibrating body portion and the contact member, for example, even if the contact member is worn, the longitudinal vibration of the vibrating body portion is reduced. It was found that the amount of change in resonance frequency can be reduced.

  FIG. 16 is a table showing the relationship between the spring constant in the low spring constant region and the amount of change in the resonance frequency of the longitudinal vibration of the vibrating body portion. The amount of change in resonance frequency for each spring constant was calculated by the same method as in FIG.

As shown in FIG. 16, it was found that the amount of change in resonance frequency can be suppressed to less than 1 kHz by setting the spring constant in the low spring constant region to 5 × 10 ⁵ N / m or less.

3.5. Calculation for Adhesive Thickness In order to obtain “1.6 × 10 ⁶ N / m spring constant K _T ” when the low spring constant region is an adhesive, the thickness of the adhesive (large in the longitudinal direction) is obtained. The calculation of how much T (see FIG. 3) should be set. As shown in FIG. 3, the shape of the contact member and the shape of the adhesive were rectangular parallelepiped. The contact area S between the contact member and the adhesive was 1 × 10 ⁻⁸ m ² .

FIG. 17 is a table showing the thickness T of the adhesive when K _T = 1.6 × 10 ⁶ N / m when the Young's modulus E of the adhesive is changed. The thickness T was determined by the following formula (11).

The Young's modulus of a silicone-based and urethane-based adhesive (for example, an elastic adhesive 590 manufactured by 3M) is about 3 × 10 ⁷ Pa. Therefore, when such an adhesive is used, the spring constant of the adhesive can be made 1.6 × 10 ⁶ N / m or less as shown in FIG. 17 if the thickness is made 0.19 μm or more.

The Young's modulus of a silicone-based adhesive (for example, DA6501 Dow Corning manufactured by Toray Industries, Inc.) is about 9 × 10 ⁵ Pa. Therefore, when such an adhesive is used, the spring constant of the adhesive can be made 1.6 × 10 ⁶ N / m or less from FIG. 13 if the thickness is made 0.0056 μm or more.

The Young's modulus of an epoxy adhesive (for example, 342-37 manufactured by Able Stick) is about 2.94 × 10 ⁹ Pa. Accordingly, when such an adhesive is used, the spring constant of the adhesive can be made 1.6 × 10 ⁶ N / m or less as shown in FIG. 13 if the thickness is made 18 μm or more.

  Among the above three adhesives, in consideration of miniaturization of the piezoelectric driving device, silicone-based and urethane-based adhesives or silicone-based adhesives are preferable.

4). 4. Modified example of piezoelectric drive device 4.1. First Modification Next, a piezoelectric drive device according to a first modification of the present embodiment will be described with reference to the drawings. FIG. 18 is a plan view schematically showing a piezoelectric driving device 200 according to a first modification of the present embodiment.

  Hereinafter, in the piezoelectric driving device 200 according to the first modification of the present embodiment, members having the same functions as those of the constituent members of the piezoelectric driving device 100 according to the present embodiment are denoted by the same reference numerals, and detailed description thereof is given. Is omitted. The same applies to the piezoelectric drive device according to the second modification of the present embodiment described below.

  In the piezoelectric drive device 100 described above, as shown in FIG. 3, the shape of the contact member 20 is a rectangular parallelepiped. On the other hand, in the piezoelectric drive device 200, as shown in FIG. 18, the shape of the contact member 20 is spherical. In the illustrated example, a notch 13 is provided in the vibrating body 12, and the notch 13 is filled with a low spring constant region 22 that is an adhesive. The contact member 20 is bonded by a low spring constant region 22 in the notch 13.

  In the piezoelectric driving device 200, similarly to the piezoelectric driving device 100, the difference between the resonance frequency of the longitudinal vibration of the vibrating body portion and the resonance frequency of the bending vibration can be reduced.

4.2. Second Modified Example Next, a piezoelectric driving device according to a second modified example of the present embodiment will be described with reference to the drawings. FIG. 19 is a plan view schematically showing a piezoelectric driving device 300 according to a second modification of the present embodiment.

  In the piezoelectric driving device 100 described above, as shown in FIG. 3, the low spring constant region 22 is an adhesive. On the other hand, in the piezoelectric driving device 300, as shown in FIG. 19, the low spring constant region 22 is a plastic sheet. The material of the low spring constant region 22 is, for example, a resin such as ABS, polyurethane, or polyethylene.

  The low spring constant region 22, which is a plastic sheet, is provided between the vibrating body portion 12 and the contact member 20. The low spring constant region 22 is bonded to the vibrating body portion 12 with an adhesive 24. The contact member 20 is bonded to the low spring constant region 22 with an adhesive 25.

  In the piezoelectric driving device 300, similarly to the piezoelectric driving device 100, the difference between the resonance frequency of the longitudinal vibration of the vibrating body portion and the resonance frequency of the bending vibration can be reduced.

  Furthermore, in the piezoelectric driving device 300, since the low spring constant region 22 is a separate member from the adhesive (because the low spring constant region 22 is not an adhesive), the thicknesses and Young's modulus are not considered as the adhesives 24 and 25. In addition, a material having high adhesiveness can be selected.

5). Device Using Piezoelectric Drive Device The piezoelectric drive device according to the present invention can apply a large force to a driven body by utilizing resonance, and can be applied to various devices. The piezoelectric drive device according to the present invention is, for example, as a drive device in various devices such as a robot (including an electronic component transfer device (IC handler)), a dosing pump, a calendar feeding device for a clock, and a paper feeding mechanism for a printing device. Can be used. Hereinafter, representative embodiments will be described. Hereinafter, an apparatus including the piezoelectric driving apparatus 100 will be described as the piezoelectric driving apparatus according to the present invention.

5.1. Robot FIG. 20 is a diagram for explaining a robot 2050 using the piezoelectric driving device 100. The robot 2050 includes an arm 2010 (a plurality of link portions 2012 (also referred to as “link members”) and 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 a piezoelectric drive device 100, and the joint portion 2020 can be rotated or bent by an arbitrary angle using the piezoelectric drive device 100. 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 100, and the piezoelectric driving device 100 can be used to open and close the gripping unit 2003 to grip an object. Further, the piezoelectric driving device 100 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 driving device 100.

  FIG. 21 is a diagram for explaining 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 100, and the piezoelectric driving device 100 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 is movable in the robot hand 2000, and the piezoelectric drive device 100 is mounted on the base portion of the grip portion 2003. For this reason, by operating the piezoelectric driving device 100, the gripping portion 2003 can be moved to grip the target. The robot is not limited to a single-arm robot, and the piezoelectric drive device 100 can be applied to a multi-arm robot having two or more arms.

  Here, in the wrist joint 2020 and the robot hand 2000, in addition to the piezoelectric drive device 100, 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 wiring inside the joint portion 2020 and the robot hand 2000. However, since the piezoelectric drive device 100 can reduce the drive current as compared with a normal electric motor, wiring can be arranged even in a small space such as the joint portion 2020 (particularly, the joint portion at the tip of the arm 2010) or the robot hand 2000. Is possible.

5.2. Pump FIG. 22 is a diagram for explaining an example of a liquid feed pump 2200 using the piezoelectric driving device 100. The liquid feed pump 2200 includes a reservoir 2211, a tube 2212, a piezoelectric driving device 100, 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, 2219.

  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 contact member 20 of the piezoelectric driving device 100 is provided in a state of being pressed against the side surface of the rotor 2222, and the piezoelectric driving device 100 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 feed a very small amount with high accuracy.

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, since the drive current can be made smaller than that of a normal electric motor by using the piezoelectric drive device 100, the power consumption of the dosing device can be suppressed. Therefore, it is particularly effective when the medication apparatus is battery-driven.

  In the present invention, a part of the configuration may be omitted within a range having the characteristics and effects described in the present application, or each embodiment or modification may be combined.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 4 ... Rotor, 4a ... Center, 10 ... Board | substrate, 12 ... Vibrating body part, 12a ... End part, 13 ... Notch, 14 ... Fixed part, 16 ... 1st connection part, 18 ... 2nd connection part, 20 ... Contact Member, 22 ... low spring constant region, 24, 25 ... adhesive, 30, 30a, 30b, 30c, 30d, 30e ... piezoelectric element, 32 ... first electrode, 34 ... piezoelectric layer, 36 ... second electrode, 100 DESCRIPTION OF SYMBOLS ... Piezoelectric drive device, 110 ... Drive circuit, 120 ... Motor, 2000 ... Robot hand, 2003 ... Gripping part, 2010 ... Arm, 2012 ... Link part, 2020 ... Joint part, 2050 ... Robot, 2200 ... Liquid feed pump, 2202 ... Cam, 2202A ... projection, 2211 ... reservoir, 2212 ... tube, 2213, 2214, 2215, 2216, 2217, 2218, 2219 ... finger, 2222 ... Ta, 2223 ... deceleration transmission mechanism, 2230 ... case

Claims (6)

A fixed portion, and a substrate having a vibrating body portion provided with a piezoelectric element and supported by the fixed portion;
A contact member that contacts the driven body and transmits the movement of the vibrating body portion to the driven body;
Including
The contact member is provided on the vibrating body part via an adhesive,
A low spring constant region having a spring constant equal to or less than an initial spring constant is provided between the vibrating body portion and the contact member,
The low spring constant region includes the adhesive,
The initial spring constant is a spring constant of a system in which a first phantom sphere having the same material and the same volume as the contact member is pressed against a second phantom sphere having the same material and the same volume as the driven body. apparatus. In claim 1,
The Young's modulus of the first phantom sphere is E ₁ , the Poisson's ratio is ν ₁ , the radius is R ₁ ,
The Young's modulus of the second phantom sphere is E ₂ , the Poisson's ratio is ν ₂ , the radius is R ₂ ,
When the radius of the contact surface between the first phantom sphere and the second phantom sphere when the first phantom sphere is pressed against the second phantom sphere with the pressing force F ₀ is a ₀ , the low spring constant The spring constant K of the region is
Piezoelectric drive device that satisfies the above relationship.
However,
It is. In claim 1 or 2,
The low-spring constant region is the piezoelectric drive device, which is the adhesive. A piezoelectric driving device according to any one of claims 1 to 3,
A rotor rotated by the piezoelectric drive device;
Including a motor. A plurality of link parts;
A joint part connecting a plurality of the link parts;
The piezoelectric drive device according to any one of claims 1 to 3, wherein a plurality of the link portions are rotated by the joint portions;
Including robots. A piezoelectric driving device according to any one of claims 1 to 3,
A tube that transports the liquid;
A plurality of fingers for closing the tube by driving the piezoelectric driving device;
Including a pump.