JP2017103955A - Piezoelectric driving device, motor, robot, and pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric driving device that can stabilize output characteristics by specifying the amount of deformation of a contact part due to a pressing force.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 part 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 part is provided at an end in the longitudinal direction of the vibrator part; the difference between the distance between the end and a leading end of the contact part when the contact part is not pressed against the driving target body and the distance between the end and the leading end when the contact part is pressed against the driving target body is smaller than the amplitude of the longitudinal direction when the vibrator part is driven.SELECTED DRAWING: Figure 4

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

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

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

  One of the objects according to some aspects of the present invention is to provide a piezoelectric driving device capable of stabilizing output characteristics by specifying the amount of deformation of a contact portion due to pressing. 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 portion that contacts the driven body and transmits the movement of the vibrating body portion to the driven body;
Including
The contact portion is provided at an end portion in the longitudinal direction of the vibrating body portion,
The distance between the end when the contact portion is not pressed against the driven body and the tip of the contact portion, and the end when the contact portion is pressed against the driven body And the distance between the tip and the tip is smaller than the amplitude in the longitudinal direction when the vibrating body portion is driven.

  In such a piezoelectric drive device, the contact portion can repeat contact and separation with the driven body during driving of the vibrating body portion (of the piezoelectric drive device). As a result, in such a piezoelectric drive device, the output characteristics can be stabilized.

[Application Example 2]
In application example 1,
When the amplitude is X ₀ and the pressing force of the driven body to the contact portion is F ₀ , the spring constant K in the longitudinal direction of the contact portion is
K> F ₀ / X ₀
May be satisfied.

  In such a piezoelectric driving device, the distance between the end of the vibrating body portion and the tip of the contact portion when the contact portion is not pressed against the driven body, and the contact portion is pressed against the driven body. In this case, the difference between the distance between the end of the vibrating body portion and the tip of the contact portion can be made smaller than the amplitude in the longitudinal direction when the vibrating body portion is driven.

[Application Example 3]
In application example 2,
The contact portion includes a tip portion constituting the tip, and an adhesive portion provided between the tip portion and the vibrating body portion,
The length in the longitudinal direction of the tip portion is Ls, the length in the width direction perpendicular to the longitudinal direction of the contact surface between the tip portion and the adhesive portion is Ws, and the length direction and the width of the contact surface are When the length in the direction orthogonal to the direction is Ts, the Young's modulus of the tip portion is Es, and the Young's modulus of the adhesive portion is Ea, the length La in the longitudinal direction of the adhesive portion is:
La <(X ₀ / F ₀ ) × Ea × Ws × Ts− (Ls × Ea) / Es
May be satisfied.

  In such a piezoelectric driving device, the distance between the end of the vibrating body portion and the tip of the contact portion when the contact portion is not pressed against the driven body, and the contact portion is pressed against the driven body. In this case, the difference between the distance between the end of the vibrating body portion and the tip of the contact portion can be made smaller than the amplitude in the longitudinal direction when the vibrating body portion is driven.

[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 top view which shows typically the piezoelectric drive device which concerns on this embodiment. The perspective view which shows typically the piezoelectric drive device which concerns on this embodiment. 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 top view which shows typically the piezoelectric drive device which concerns on the 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. 3 and 4 are plan views schematically showing the vicinity of the contact portion 20 of the piezoelectric driving device 100 according to the present embodiment. FIG. 5 is a perspective view schematically showing the vicinity of the contact portion 20 of the piezoelectric driving device 100 according to the present embodiment.
As shown in FIGS. 1 to 5, the piezoelectric driving device 100 includes a substrate 10, a contact portion 20, 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 portion 20 is provided at the end portion 12 a in the longitudinal direction of the vibrating body portion 12 (hereinafter, also simply referred to as “longitudinal direction”). 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). The contact portion 20 is a protruding portion that protrudes from the end portion 12a. In the illustrated example, the shape of the contact portion 20 is a rectangular parallelepiped. Contact part 2
0 has a tip 20a, and the contact portion 20 contacts the driven member (specifically, the rotor 4 shown in FIGS. 3 and 4) at the tip 20a to drive the movement of the vibrating body portion 12. It is a member that is transmitted to the member. The shape of the rotor 4 is, for example, a cylindrical shape or a spherical shape. The tip 20a is a surface opposite to the surface in contact with the end 12a of the contact portion 20.

The contact portion 20 includes a tip portion 22 constituting the tip 20 a and an adhesive portion 24 provided between the tip portion 22 and the vibrating body portion 12. The material of the tip 22 is, for example, ceramics (specifically, alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N), or a mixture thereof). The adhesive portion 24 is configured by an adhesive that adheres the distal end portion 22 and the vibrating body portion 12. In the illustrated example, the shapes of the tip portion 22 and the adhesive portion 24 are rectangular parallelepipeds.

Here, the distance L _X0 (see FIG. 3) between the end 12a and the tip 20a when the contact portion 20 is not pressed against the rotor 4 (when not pressed), and the contact portion 20 against the rotor 4 The difference δx between the distance L _X1 (see FIG. 4) between the end portion 12a and the tip end 20a when is pressed (pressed) is a vibrating body when the vibrating body portion 12 is driven longitudinal lower amplitude _{X 0} parts 12. The boundary part (connection part) with the contact part 20 of the vibrating body part 12 is driven to draw an ellipse by driving the piezoelectric element 30. Amplitude X ₀ is, for example, a length in the longitudinal direction component of the vibration body 12 of the ellipse boundary of the vibrating body 12 is drawn. In the illustrated example, the amplitude X ₀ is the length of the minor axis of the ellipse drawn by the boundary portion of the vibrating body portion 12.

When the vibrating body 12 is driven, the longitudinal amplitude X ₀ of the vibrating body 12 and the pressing force (pressing force in the longitudinal direction) on the contact portion 20 of the rotor 4 is F _0. The spring constant K in the direction satisfies the relationship of the following formula (1).

K> F ₀ / X ₀ (1)

  The contact portion 20 has a spring constant that deforms to some extent when the rotor 4 is pressed against it.

  As shown in FIG. 5, the length in the longitudinal direction of the tip portion 22 is Ls, the length in the width direction perpendicular to the longitudinal direction of the contact surface 23 between the tip portion 22 and the adhesive portion 24 is Ws, and the length of the contact surface 23 is When the length in the direction perpendicular to the longitudinal direction and the width direction is Ts, the Young's modulus of the tip portion 22 is Es, and the Young's modulus of the adhesive portion 24 is Ea, the length La in the longitudinal direction of the adhesive portion 24 is The relationship of Formula (2) is satisfy | filled. Furthermore, the length La preferably satisfies the relationship of the following formula (3).

La <(X ₀ / F ₀ ) × Ea × Ws × Ts− (Ls × Ea) / Es (2)
La <(1/2) × (X ₀ / F ₀ ) × Ea × Ws × Ts− (1/2) × (Ls × Ea) / Es (3)

The length Ws is, for example, not less than 0.1 mm and not more than 0.5 mm. The length Ls is, for example, not less than 0.1 mm and not more than 0.5 mm. The length Ts is, for example, not less than 0.1 mm and not more than 0.5 mm. Amplitude _{X 0} is, for example, 0.1μm or more 5μm or less. More specifically, Ws = 0.2 mm, Ts = 0.2 mm, Ls = 0.1 mm, and X ₀ = 1 μm.

  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 shown in FIG.
The planar shape 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 piezoelectric elements 30a to 30d have the same area, and the piezoelectric element 30e has a larger area than the piezoelectric elements 30a to 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. 6 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. 6, 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) in contact with the contact portion 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. Moreover, the rotor which contacts the contact part 20 can be rotated in a reverse direction by applying an alternating voltage or a pulsating current voltage between the electrodes 32 and 36 of the piezoelectric elements 30b, 30c and 30e.

  FIG. 7 is a diagram for explaining the operation of the vibrating body 12 of the piezoelectric driving device 100. As shown in FIG. 7, the contact portion 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 portion 12 as described above, the boundary portion between the vibrating body portion 12 and the contact portion 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. 7, 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, the distance L _X0 between the end 12 a and the tip 20 a when the contact portion 20 is not pressed against the rotor 4, and the end when the contact portion 20 is pressed against the rotor 4. 12a and the distance _{L X1} between the front end 20a, the difference δx is smaller than the amplitude _{X 0} in the longitudinal direction when the vibrating body 12 is driven. Therefore, in the piezoelectric driving device 100, the contact portion 20 can repeat contact and separation with the rotor 4 during driving of the vibrating body portion 12 (of the piezoelectric driving device 100). As a result, the piezoelectric drive device 100 can stabilize the output characteristics.

For example, if it when the difference δx is above the amplitude X _0, during the operation of the vibrator part 12, the contact portion 20 will be always in contact with the rotor 4, it may not be possible to rotate the rotor 4. As a result, the output characteristics may become unstable.

The piezoelectric drive device 100 satisfies the formula (1). Thus, the piezoelectric driver 100, (see "3. Experimental Example" which will be described in detail later) that it is possible to reduce the difference δx than the amplitude X _0.

The piezoelectric driving device 100 satisfies the formula (2). Thus, the piezoelectric driver 100, (see "3. Experimental Example" which will be described in detail later) that it is possible to reduce the difference δx than the amplitude X _0. For example, in a piezoelectric drive device 100, based on equation (2), by adjusting the length La of the adhesive portion 24, it is possible to reduce the difference δx than the amplitude X _0.

Here, since the piezoelectric driving device 100 is used for, for example, a small robot, the piezoelectric driving device 100 is also required to be downsized and have stable output characteristics. Therefore, there is a case where the amplitude _{X 0} and the length Ws, Ls, it is impossible to increase the Ts. Further, the material of the tip 22 is limited in addition to the size in order to ensure durability. Furthermore, the material of the adhesive part 24 is limited in order to ensure the adhesiveness between the tip part 22 and the vibrating body part 12. That is, the changeable range of the parameters of the amplitude X ₀ , the length Ws, Ts, Ls, and the Young's modulus Es, Ea is narrow (the degree of freedom is low). Therefore, it may be difficult to change these parameters to achieve the difference δx smaller than the amplitude X ₀ . Therefore, as described above, based on the equation (2), by adjusting the length La of the adhesive portion 24, there is a case where the difference δx becomes effective to reduce than the amplitude X _0.

The piezoelectric driving device 100 satisfies the formula (3). Therefore, in the piezoelectric driving device 100, the contact portion 20 is brought into contact with the rotor 4 in the upper half (half on the rotor 4 side) of the longitudinal amplitude X ₀ when the vibrating body portion 12 is driven, and the amplitude X ₀ In the lower half (half opposite to the rotor 4), the contact portion 20 can be separated from the rotor 4 (refer to “3. Experimental example” described later for details). Thereby, in the piezoelectric drive device 100, the contact part 20 can transmit the motion of the vibrating body part 12 to the rotor 4 efficiently. Incidentally, the difference δx may be less than half the amplitude X _0.

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 distal end portion 22 is bonded to the end portion 12 a of the vibrating body portion 12 via the adhesive portion 24. Thereby, the contact part 20 can be provided in the edge part 12a.

  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 Formula (1) As shown in FIG. 4, when the deformation amount of the contact portion when the rotor is pressed against the contact portion with force (pressing force) F ₀ is δx, the spring constant K in the longitudinal direction of the contact portion Becomes the following formula (4), and the following formula (5) can be obtained by expanding the formula (4).

K = F ₀ / δx (4)
δx = F ₀ / K (5)

On the other hand, the spring constant K _{0 in} the longitudinal direction of the contact portion when deformed by the same amount (length) as the amplitude X ₀ of the vibrating body portion is expressed by the following equation (6). (7) can be obtained.

K ₀ = F ₀ / X ₀ (6)
X ₀ = F ₀ / K ₀ (7)

For deformation amount .delta.x is smaller than the amplitude _{X 0} is because .delta.x _{<X 0,} the equation (5) and (7), can be obtained the following expression (8), further expand the formula (8) Thus, the following formula (9) can be obtained. Then, Expression (1) can be obtained from Expression (6) and Expression (9).

F ₀ / K <F ₀ / K ₀ (8)
K> K ₀ ... (9)
K> F ₀ / X ₀ (1)

3.2. Calculation of Formula (2) The spring constant Ks at the tip of the contact portion is expressed by the following formula (10). Moreover, the spring constant Ka of the adhesive part of a contact part becomes following formula (11).

Ks = Es × (Ws × Ts) / Ls (10)
Ka = Es × (Ws × Ts) / La (11)

  If the following formula (12) is satisfied, the contact portion 20 can repeat contact and separation with the rotor 4 during driving of the vibrating body portion 12.

1 / ((1 / Ka) + (1 / Ks))> F ₀ / X ₀ (12)

Expression (12) can be expanded to obtain the following expressions (13) and (14), and expressions (10) and (1
The following formula (15) can be obtained from 1) and (14). Then, Expression (15) can be expanded to obtain Expression (2).

1 / Ka + 1 / Ks <X ₀ / F ₀ (13)
1 / Ka <X ₀ / F ₀ −1 / Ks (14)
La / (Ea × Ws × Ts) <X ₀ / F ₀ −Ls / (Es × Ws × Ts) (15)
La <(X ₀ / F ₀ ) × Ea × Ws × Ts− (Ls × Ea) / Es (2)

For example, when alumina is used as the tip, an elastic adhesive 590 manufactured by 3M is used as the adhesive layer, and each parameter is set as follows, La <1.5 × 10 ⁻⁶ m from Equation (2). It becomes.

F ₀ = 0.4N
X ₀ = 5 × 10 ⁻⁷ m
Es = 3.7 × 10 ¹¹ Pa
Ws = 2 × 10 ⁻⁴ m
Ls = 1 × 10 ⁻⁴ m
Ts = 2 × 10 ⁻⁴ m
Ea = 3 × 10 ⁷ Pa

Furthermore, the following formula (3) can be obtained by performing the same calculation as the above formula (16). Equation (16), an amount corresponding to half the amplitude X ₀ (length) only, a condition in which the contact portion is deformed. Therefore, by satisfying the equation (3), in half of the amplitude X _0, the contact portion is brought into contact with the rotor, the other half of the amplitude X _0, you are possible to separate the contact portion from the rotor 4.

δx = (1/2) × X ₀ (16)
La <(1/2) × (X ₀ / F ₀ ) × Ea × Ws × Ts− (1/2) × (Ls × Ea) / Es (3)

4). Modified Example of Piezoelectric Drive Device Next, a piezoelectric drive device according to a modified example of this embodiment will be described with reference to the drawings. FIG. 8 is a plan view schematically showing a piezoelectric driving device 200 according to a modification of the present embodiment. Hereinafter, in the piezoelectric driving device 200 according to the modified example 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 omitted. To do.

  In the piezoelectric drive device 100 described above, as shown in FIG. 3, the adhesive portion 24 is provided only between the tip portion 22 and the vibrating body portion 12. On the other hand, in the piezoelectric driving device 200, the adhesive portion 24 is also provided on the side of the tip portion 22 as shown in FIG.

  In the piezoelectric driving device 200, as in the piezoelectric driving device 100, the output characteristics can be stabilized. Further, in the piezoelectric driving device 200, the adhesive strength between the tip portion 22 and the vibrating body portion 12 is increased as compared with the case where the adhesive portion 24 is provided only between the tip portion 22 and the vibrating body portion 12. be able to.

  The calculation of “3. Experimental example” can also be applied to the piezoelectric driving device 200. In this case, the distal end portion 22, the adhesive portion 24, and the contact surface 23 are surfaces that are not side surfaces of the distal end portion 22 (surfaces parallel to the end portion 12a in the illustrated example).

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. 9 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. 10 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. 11 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 portion 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, 14 ... Fixed part, 16 ... 1st connection part, 18 ... 2nd connection part, 20 ... Contact member, 20a ... Tip 22 ... tip part, 23 ... contact surface, 24 ... adhesive part, 30, 30a, 30b, 30c, 30d, 30e ... piezoelectric element, 32 ... first electrode, 34 ... piezoelectric layer, 36 ... second electrode, DESCRIPTION OF SYMBOLS 100 ... 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 feeding 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 portion that contacts the driven body and transmits the movement of the vibrating body portion to the driven body;
Including
The contact portion is provided at an end portion in the longitudinal direction of the vibrating body portion,
The distance between the end when the contact portion is not pressed against the driven body and the tip of the contact portion, and the end when the contact portion is pressed against the driven body And the distance between the tip and the tip is a piezoelectric drive device that is smaller than the amplitude in the longitudinal direction when the vibrating body portion is driven. In claim 1,
When the amplitude is X ₀ and the pressing force of the driven body to the contact portion is F ₀ , the spring constant K in the longitudinal direction of the contact portion is
K> F ₀ / X ₀
Piezoelectric drive device that satisfies the above relationship. In claim 2,
The contact portion includes a tip portion constituting the tip, and an adhesive portion provided between the tip portion and the vibrating body portion,
The length in the longitudinal direction of the tip portion is Ls, the length in the width direction perpendicular to the longitudinal direction of the contact surface between the tip portion and the adhesive portion is Ws, and the length direction and the width of the contact surface are When the length in the direction orthogonal to the direction is Ts, the Young's modulus of the tip portion is Es, and the Young's modulus of the adhesive portion is Ea, the length La in the longitudinal direction of the adhesive portion is:
La <(X ₀ / F ₀ ) × Ea × Ws × Ts− (Ls × Ea) / Es
Piezoelectric drive device that satisfies the above relationship. 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.

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