JP2016082835A - Piezoelectric drive device, finger assist device and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a driving device and a driven section from being locked even when a control device is stuck.SOLUTION: A finger assist device comprises: a driving section having a piezoelectric material; a driven section capable of being brought into contact with the driving section; and a movable section capable of being brought into contact with the driving section. The movable section has a first state and a second state. Pressing force from the driving section to the driven section in the first state less than pressing force from the driving section to the driven section in the second state.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a piezoelectric drive device, a finger assist device, and a robot.

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

JP 2004-320979 A

  Conventionally, a free mode (free state) in which the rotor can be freely rotated by the control of the control device has been used. However, when the control device freezes, there is a problem that the piezoelectric driving device (driving unit) is locked in a state where the protruding portion is pressed against the rotor, and the rotor (driven portion) cannot be moved. Further, the inventor of the present application has found a problem that it is difficult to remove the finger assist device from the finger when such a freeze occurs when the piezoelectric drive device is used as a drive device for the finger assist device. .

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

(1) According to one aspect of the present invention, a piezoelectric driving device is provided. The piezoelectric driving device includes a driving unit having a piezoelectric body, a driven unit that can come into contact with the driving unit, and a movable unit that can come into contact with the driving unit, and the movable unit has a first state and a first state. The pressing force from the driving unit to the driven unit in the first state is smaller than the pressing force from the driving unit to the driven unit in the second state. According to this aspect, if the movable portion is in the first state, the pressing force from the drive portion to the driven portion can be reduced as compared with the second state. It can be moved.

(2) In the piezoelectric driving device according to the aspect described above, in the first state, the movable unit may separate the driving unit from the driven unit. According to this aspect, if the drive unit and the driven unit are separated from each other, the driven unit can be moved freely.

(3) In the piezoelectric drive device according to the aspect described above, the movable unit includes an input unit that receives an external force, and is capable of transitioning between the first state and the second state by receiving the external force. May be. According to this aspect, by inputting an external force to the movable part, it is possible to transition between a state where the driven part can be moved (first state) and a state where the driven part cannot be moved (second state).

(4) In the piezoelectric driving device according to the above aspect, when the electric power is not applied to the piezoelectric body and the movable portion is in the second state, the driving portion and the driven portion are in contact with each other. You may do it. According to this aspect, when the electric power is not applied to the piezoelectric body, the driven portion can be locked so as not to move.

(5) In the piezoelectric drive device according to the above aspect, the movable portion may be an eccentric body or a slide member. According to this embodiment, the movable part can be realized with a simple configuration.

(6) According to an aspect of the present invention, a finger assist device is provided. The finger assist device includes the piezoelectric driving device according to the above aspect, a first driven body that is rotated by the piezoelectric driving device and has a circular shape, a speed reducer that decelerates the rotation of the first driven body, A second driven body that is connected to the speed reducer and assists the movement of the finger.

(7) The finger assist device of the above aspect may include an encoder.

(8) According to one aspect of the present invention, a robot is provided. This robot is equipped with the piezoelectric drive device of the said form.

  The present invention can be realized in various forms. For example, the present invention can be realized in various forms such as a piezoelectric drive device and a finger assist device, as well as a finger assist device and a robot.

Explanatory drawing which shows the finger assistance apparatus which concerns on 1st Embodiment. The top view and sectional drawing which show schematic structure of a piezoelectric drive device. The top view of a diaphragm. Explanatory drawing which shows the electrical connection state of a piezoelectric drive device and a drive circuit. Explanatory drawing which shows the example of operation | movement of a piezoelectric drive device. The schematic diagram which looked at the piezoelectric drive device and reduction gear of the 1st finger assist device from the opposite side to a finger. The schematic diagram which looked at the piezoelectric drive device and reduction gear of the 1st finger assist device from the finger side. Explanatory drawing which shows operation | movement of an eccentric body. Explanatory drawing which shows operation | movement of an eccentric body. Explanatory drawing which shows embodiment using the slide member instead of the eccentric body. Explanatory drawing which shows embodiment using the pushbutton switch instead of the eccentric body. Explanatory drawing which shows an example of the robot using the above-mentioned piezoelectric drive device. Explanatory drawing of the wrist part of a robot.

First embodiment:
FIG. 1 is an explanatory diagram illustrating a finger assist device 1000 according to the first embodiment. The finger assist device 1000 includes a first finger assist unit 1001, a second finger assist unit 1002, and a base member 1003. The first finger assist unit 1001 is worn from the middle phalanx to the distal phalanx of the finger 700, and assists the movement of the finger 700 at the joint between the middle phalanx and the proximal phalanx. The second finger assist unit 1002 is connected to the first finger assist unit 1001 and is attached to the proximal phalanx portion of the finger 700. At the joint between the proximal phalanx and the metacarpal bone, Assist exercise. The base member 1003 is connected to the second finger assist unit 1002 and is attached to the back of the hand.

  The first finger assist unit 1001 includes the piezoelectric driving device 10, a speed reducer 501, and a finger support unit 701. The second finger assist unit 1002 includes the piezoelectric driving device 10, a speed reducer 502, a finger support unit 702, and a band 703. Except for the band 703, the first finger assist unit 1001 and the second finger assist unit 1002 have substantially the same configuration. The band 703 fixes the second finger assist unit 1002 from the ventral side of the finger 700. The band 703 is also provided in the first finger assist unit 1001, but is omitted in FIG. In the present embodiment, the finger assist device 1000 includes the two finger assist units 1001 and 1002, but may include three finger assist units. In this case, the third finger assist unit is attached to the distal phalanx portion of the finger 700, for example. Moreover, the structure provided with only one finger assist part may be sufficient. In this case, the finger assist device 1000 may include only the second finger assist unit 1002 attached to the proximal phalanx portion of the finger 700.

  Since the second finger assist unit 1002 and the first finger assist unit 1001 have the same configuration, the first finger assist unit 1001 will be described below as an example. The piezoelectric driving device 10 is a driving device that drives a piezoelectric body by expanding and contracting by applying a voltage to the piezoelectric body. The reducer 501 is a reduction device that reduces the speed by connecting a plurality of gears in series. The piezoelectric drive device 10 and the speed reducer 501 will be described later. The finger support portion 701 is a member that supports the finger 700 from the back and side surfaces of the finger 700. The piezoelectric driving device 10 and the speed reducer 501 are provided on one side surface of the finger support portion 701. When the finger assist device 1000 is attached to the index finger, the side surface on which the piezoelectric driving device 10 and the speed reducer 501 are provided is preferably the side surface opposite to the thumb (middle finger side). The thumb has a greater degree of freedom of movement than other fingers, and when the finger assist device 1000 is attached to the thumb side, the finger assist device 1000 of the index finger may interfere with the finger assist device 1000 attached to the thumb or the thumb. Because there is. Note that the piezoelectric driving device 10 and the speed reducer 501 may be disposed on the back of the finger support portion 701.

-Configuration of the piezoelectric drive device 10:
FIG. 2A is a plan view showing a schematic configuration of the piezoelectric driving device 10 according to the first embodiment of the present invention, and FIG. 2B is a sectional view taken along the line BB in FIG. The piezoelectric driving device 10 includes a vibration plate 200 and two piezoelectric vibration members 100 arranged on both surfaces (first surface 211 and second surface 212) of the vibration plate 200, respectively. The piezoelectric vibrating body 100 includes a substrate 120, a first electrode 130 formed on the substrate 120, a piezoelectric body 140 formed on the first electrode 130, and a second electrode formed on the piezoelectric body 140. An electrode 150. The first electrode 130 and the second electrode 150 constitute a piezoelectric element by sandwiching the piezoelectric body 140. The two piezoelectric vibrators 100 are arranged symmetrically about the diaphragm 200. In this embodiment, the piezoelectric vibrating body 100 is installed on the vibration plate 200 so that the substrate 120 and the vibration plate 200 sandwich the piezoelectric element (130, 140, 150). Since the two piezoelectric vibrators 100 have the same configuration, the configuration of the piezoelectric vibrator 100 below the diaphragm 200 will be described below unless otherwise specified.

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

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

  The piezoelectric body 140 is formed as five piezoelectric layers having substantially the same planar shape as the second electrodes 150a to 150e. Alternatively, the piezoelectric body 140 may be formed as one continuous piezoelectric layer having substantially the same planar shape as the first electrode 130. Five piezoelectric elements 110a to 110e (FIG. 2A) are configured by a laminated structure of the first electrode 130, the piezoelectric body 140, and the second electrodes 150a to 150e.

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

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

  The piezoelectric vibrating body 100 (FIG. 2) is bonded to the upper surface (first surface 211) and the lower surface (second surface 212) of the vibrating body portion 210 using an adhesive. The ratio of the length L to the width W of the vibrating body part 210 is preferably L: W = about 7: 2. This ratio is a preferable value for performing ultrasonic vibration (described later) in which the vibrating body portion 210 bends left and right along the plane. The length L of the vibrating body portion 210 can be set in a range of, for example, 3.5 mm or more and 30 mm or less, and the width W can be set in a range of, for example, 1 mm or more and 8 mm or less. In addition, in order for the vibrating body part 210 to perform ultrasonic vibration, the length L is preferably set to 50 mm or less. The thickness of the vibrating body part 210 (thickness of the vibration plate 200) can be in the range of, for example, 50 μm or more and 700 μm or less. If the thickness of the vibrating body portion 210 is 50 μm or more, the vibrating body portion 210 has sufficient rigidity to support the piezoelectric vibrating body 100. Further, if the thickness of the vibrating body portion 210 is 700 μm or less, a sufficiently large deformation can be generated according to the deformation of the piezoelectric vibrating body 100.

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

  FIG. 4 is an explanatory diagram showing an electrical connection state between the piezoelectric driving device 10 and the driving circuit 300. Among the five second electrodes 150a to 150e, a pair of diagonal second electrodes 150a and 150d are electrically connected to each other via the wiring 151, and another diagonal pair of second electrodes 150b and 150c. Are also electrically connected to each other via the wiring 152. These wirings 151 and 152 may be formed by a film forming process, or may be realized by wire-like wiring. The three second electrodes 150b, 150e, and 150a in FIG. 4 and the first electrode 130 (FIG. 2) are electrically connected to the drive circuit 300 via wirings 310, 312, 314, and 320. The drive circuit 300 ultrasonically vibrates the piezoelectric drive device 10 by applying an alternating voltage or a pulsating voltage that periodically changes between the pair of second electrodes 150a and 150d and the first electrode 130, It is possible to rotate the rotor (driven body) in contact with the protrusion 20 in a predetermined rotation direction. Here, the “pulsating voltage” means a voltage obtained by adding a DC offset to an AC voltage, and the direction of the voltage (electric field) is one direction from one electrode to the other electrode. In addition, by applying an AC voltage or a pulsating current voltage between the other pair of second electrodes 150b and 150c and the first electrode 130, it is possible to rotate the rotor in contact with the protrusion 20 in the reverse direction. is there. Such voltage application is performed simultaneously on the two piezoelectric vibrating bodies 100 provided on both surfaces of the diaphragm 200. Note that the wirings (or wiring layers and insulating layers) constituting the wirings 151, 152, 310, 312, 314, and 320 shown in FIG. 4 are not shown in FIG.

In the embodiment shown in FIG. 4, the five piezoelectric elements 110a to 110e are divided into the following three groups of piezoelectric elements.
(1) First piezoelectric element group PG1: Piezoelectric elements 110a and 110d
(2) Second piezoelectric element group PG2: piezoelectric elements 110b and 110c
(3) Third piezoelectric element group PG3: Piezoelectric element 110e
The piezoelectric elements 110 included in each piezoelectric element group are always driven simultaneously. Further, since the first piezoelectric element group PG1 includes two piezoelectric elements 110a and 110d, the second electrodes 150a and 150d of these piezoelectric elements 110a and 110d are directly connected to each other via the wiring 151. The same applies to the second piezoelectric element group PG2. As another embodiment, one set of piezoelectric element groups can be configured by three or more piezoelectric elements 110. Generally, a plurality of piezoelectric elements are composed of N sets (N is an integer of 2 or more). It can be divided into piezoelectric element groups. Also in this case, when two or more piezoelectric elements 110 are included in the same piezoelectric element group, the second electrodes 150 are directly connected to each other through wiring. Here, “directly connected via wiring” means that passive elements (such as resistors, coils, capacitors, etc.) and active elements are not included in the middle of the wiring. In this embodiment, one conductive layer common to the five piezoelectric elements 110a to 110e is used as the first electrode 130, but the first electrode 130 is separated for each piezoelectric element. In addition, it is preferable that the first electrodes of two or more piezoelectric elements belonging to the same piezoelectric element group are also directly connected via a wiring.

  FIG. 5 is an explanatory diagram illustrating an example of the operation of the piezoelectric driving device 10. The protrusion 20 of the piezoelectric driving device 10 is in contact with the outer periphery of the rotor 50 as a driven body. In the example shown in FIG. 5A, the drive circuit 300 (FIG. 4) applies an alternating voltage or a pulsating voltage between the pair of second electrodes 150a and 150d and the first electrode 130, and the piezoelectric element 110a and 110d expand and contract in the direction of arrow x in FIG. In response to this, the vibrating body portion 210 of the piezoelectric driving device 10 is bent in the plane of the vibrating body portion 210 and deformed into a meandering shape (S-shape), and the tip of the protrusion 20 reciprocates in the direction of the arrow y. Or elliptical motion. As a result, the rotor 50 rotates around the rotation axis O1 in a predetermined direction z (clockwise direction in FIG. 5). Three connecting portions 220 (FIG. 3) of the diaphragm 200 described with reference to FIG. 3 are provided at the positions of the vibration nodes of the vibrating body portion 210. When the drive circuit 300 applies an AC voltage or a pulsating voltage between the other pair of second electrodes 150b and 150c and the first electrode 130, the rotor 50 rotates in the reverse direction. If the same voltage as the pair of second electrodes 150a and 150d (or the other pair of second electrodes 150b and 150c) is applied to the center second electrode 150e, the piezoelectric driving device 10 expands and contracts in the longitudinal direction. The force applied to the rotor 50 from the protrusion 20 can be further increased. Such an operation of the piezoelectric driving device 10 (or the piezoelectric vibrating body 100) is described in the above-mentioned prior art document 1 (Japanese Patent Laid-Open No. 2004-320979 or corresponding US Pat. No. 7,224,102). The disclosure of which is incorporated by reference.

  FIG. 5B shows a state in which the piezoelectric driving device 10 also curves in the thickness direction when the piezoelectric driving device 10 vibrates in the in-plane direction as shown in FIG. Such a curvature in the thickness direction is undesirable in that it causes deflection (strain) on the surface of the piezoelectric driving device 10. However, in the piezoelectric driving device 10 of the present embodiment, the piezoelectric vibrating body 100 is installed on the vibration plate 200 so that the substrate 120 and the vibration plate 200 sandwich the piezoelectric element 110 (130, 140, 150). Such undesirable deflection (strain) can be suppressed by the substrate 120. FIG. 5C is an example in which the piezoelectric vibrating body 100 is installed on the vibration plate 200 so that the substrate 120 is in contact with the vibration plate 200, contrary to FIG. 5B. In the stacked structure in FIG. 5C, undesirable deflection (strain) on the surface of the second electrode 150 may become excessively large. Therefore, as shown in FIG. 5B, it is preferable to install the piezoelectric vibrating body 100 on the vibration plate 200 so that the substrate 120 and the vibration plate 200 sandwich the piezoelectric element (130, 140, 150). By doing so, it is possible to reduce the possibility of failure or damage of the piezoelectric drive device 10. In particular, it is preferable that the substrate 120 be made of silicon because it is difficult to be damaged by bending (strain). In the present embodiment, the diaphragm 200 and the piezoelectric element 110 (130, 140, 150) are in contact with each other. Therefore, by forming a wiring layer on the diaphragm 200, a voltage can be applied to the piezoelectric element 110 via the wiring layer of the diaphragm 200. However, as shown in FIG. 5C, if the piezoelectric vibrating body 100 is installed on the vibration plate 200 so that the substrate 120 is in contact with the vibration plate 200, the drive circuit 300 and the piezoelectric elements 110 (130, 140, 150) Wiring between them is easier than in the example shown in FIG.

-Configuration of the first finger assist unit:
FIG. 6 is a schematic view of the piezoelectric driving device and the speed reducer of the first finger assist unit 1001 as viewed from the side opposite to the finger. FIG. 7 is a schematic view of the piezoelectric driving device and the speed reducer of the first finger assist unit 1001 as viewed from the finger side. In addition to the piezoelectric drive device 10 and the speed reducer 501, the first finger assist unit 1001 includes a first driven body 50 (rotor 50), a second driven body 59, an encoder 601, and a leaf spring 400. The eccentric pin 450 is provided. The configuration of the piezoelectric driving device 10 is as described above. The first driven body 50 is a circular plate that is rotationally driven by the piezoelectric driving device 10.

  The leaf spring 400 is disposed on both surfaces of the piezoelectric driving device 10 and includes a first part 410, a second part 420, and a third part 430. The first portion has an elongated shape whose longitudinal direction is parallel to the longitudinal direction of the finger support portion 701, and is attached to the finger support portion 701 with a screw 242. The 1st site | part 410 should just be fixed with the finger | toe support part 701, The shape is arbitrary. The second portion has a substantially rectangular shape, and is attached to the attachment portion 230 (FIG. 3) of the diaphragm 200 with a screw 240. In addition, since the piezoelectric vibrating body 100 exists on both surfaces of the vibration plate 200, a washer is bitten between the attachment portion 230 and the second portion 420. The second portion 420 may be attached to the attachment portion 230 of the diaphragm 200, and the shape thereof is arbitrary. The diaphragm 200 and the piezoelectric vibrating body 100 are sandwiched between two second parts 420. In the above-described embodiment, the configuration in which the leaf spring 400 is provided on both surfaces of the piezoelectric driving device 10 is employed. However, the configuration in which the leaf spring 400 is disposed on one surface of the piezoelectric driving device 10 may be employed. The third portion 430 is two elongated portions that connect the first portion 410 and the second portion. When the piezoelectric vibrating body 100 is extended, the protrusion 20 at the tip of the vibrating plate 200 presses the first driven body 50. At this time, the piezoelectric vibrating body 100, the diaphragm 200, and the second portion 420 of the leaf spring move in the opposite direction to the first driven body 50 by the reaction force against the pressing force. When the second part 420 moves in the direction opposite to the first driven body 50, the third part is deformed because the first part 410 is fixed to the finger support portion 701. The leaf spring 400 functions as a spring by a restoring force that attempts to return to the undeformed state from the deformation of the third part.

  The eccentric body 450 is a member that can rotate around the rotation shaft 452, and is provided in the finger support portion 701. The rotation shaft 452 is at a position shifted from the center of the eccentric body 450. A groove 454 for inserting a flathead screwdriver is dug in the rotating shaft 452. The groove 454 functions as an input unit that receives an external force from the minus driver. The shape of the groove 454 may be a shape for a screwdriver, a hexagonal screwdriver, or any other special driver other than the shape for a flathead screwdriver. The operation of the eccentric body 450 will be described later.

  The speed reducer 501 includes a plurality of gears 51, 52, 53, 54, and 55. The gear 51 is a gear having the same rotation axis O <b> 1 as the first driven body 50, and is a small diameter gear having a diameter smaller than the diameter of the first driven body 50. The gear 52 is a gear that meshes with the gear 51 and is a large-diameter gear having a diameter larger than the diameter of the gear 51. As a result, the rotation speed of the gear 52 is smaller than the rotation speed of the gear 51. The gear 53 is a gear having the same rotation axis O <b> 2 as the gear 52, and is a small diameter gear having a diameter smaller than the diameter of the gear 52. The rotation speed of the gear 53 and the rotation speed of the gear 52 are the same. The gear 53 is drawn with a broken line because it is hidden behind the gear 52 in FIG. 6, and is not shown in FIG. 7. The gear 54 is a gear that meshes with the gear 53 and is a large-diameter gear having a diameter larger than the diameter of the gear 53. As a result, the rotation speed of the gear 54 is smaller than the rotation speed of the gear 53. The gear 55 is a gear having the same rotation axis O <b> 3 as the gear 54, and is a small diameter gear having a diameter smaller than the diameter of the gear 54. The rotation speed of the gear 55 and the rotation speed of the gear 54 are the same.

  At one end of the second driven body 59, a gear portion 59g that meshes with the small-diameter gear 55 at the final stage of the speed reducer 501 is formed. The other end of the second driven body 59 is connected to the finger support portion 702 of the second finger assist portion 1002. When the first piezoelectric driving device 10 rotates the first driven body 50 by driving the first finger assist section 1001, the gear 52, the gear 54, and the gear section 59g are moved from the first driven body 50. The rotation speed decreases in the order of. As a result, the gear portion 59g of the second driven 59 is rotated at a rotation speed lower than the rotation speed of the first driven body 50. Note that the torque of the second driven body 59 increases conversely. In addition, the finger assist unit 1001 includes the speed reducer 501 so that backlash can be suppressed.

  In the present embodiment, the first driven body 50 and the gears 51, 52, 53, 54, and 55 are arranged substantially in a straight line. Accordingly, a large reduction ratio can be obtained, and the size of the reduction gear 501 in the height direction can be reduced. As a result, the size of the first finger assist unit 1001 can be reduced. In the present embodiment, five gears are used for the reducer 501, but the number and diameter of the gears can be arbitrarily set according to a desired reduction ratio.

  The encoder 601 includes four gears 60, 61, 62, 63, a disc 64, and optical sensors 66A, 66B. The gear 60 is a gear that meshes with the gear 53 of the reduction gear 501. The gear 61 meshes with the gear 60, and the gear 62 is a gear having the same rotational axis as the gear 61 and is a large-diameter gear having a diameter larger than the diameter of the gear 61. The gear 63 meshes with the gear 62, and the disc 64 is a disc having the same rotational axis as that of the gear 63. The disc 64 includes slits 65 formed at a predetermined pitch. The optical sensors 66 </ b> A and 66 </ b> B are photointerrupters that irradiate the rotating disk 64 with light and detect the position of the slit 65 based on whether or not the light passes through the slit 65. The four gears 60, 61, 62, 63 may have a rotational speed of the disc 64 higher than that of the first driven body 50 by appropriately setting the diameter thereof. If the rotational speed of the disk 64 is increased, the number of pulses per unit time increases, so that the resolution of the encoder can be increased. It is not necessary to provide all the gears 60, 61, 62, 63, and any number of the gears 60, 61, 62, 63 can be used as long as the disk 64 can be rotated in synchronization with the first driven body 50. Or can be omitted.

  The diameter of the disk 64 is smaller than the diameter of the first driven body 50 and the diameters of the large diameter gears 52 and 54 of the speed reducer 501. The “large diameter gear” means a gear having a larger diameter among the two large and small gears provided coaxially. In this embodiment, the diameters of the gears 52 and 54 are substantially the same, but the diameter of the disc 64 is preferably smaller than the diameter of the largest gear of the gears 52 and 54. Further, when the first finger assist unit 1001 is viewed from the side opposite to the finger, the disc 64 is hidden behind the large-diameter gears 52 and 54 and cannot be seen. Thus, it is preferable to arrange the disc 64 so that the disc 64 is hidden by the large-diameter gears 52 and 54.

  The disc 64 has a slit 65 formed along the circumference. The width of the slit 65 in the direction along the circumference and the width of the non-slit portion are preferably the same length. The optical sensors 66A and 66B are arranged so as to sandwich the disc 64. The periods of the signals generated by the optical sensors 66A and 66B are the same. The optical sensors 66A and 66B may be arranged so that the phase of the signal generated by the optical sensor 66A and the phase of the signal generated by the optical sensor 66B are shifted by π / 2 when this period is 2π. preferable. In the present embodiment, the slit 65 is provided in the disc 64, but a reflecting plate may be provided in place of the slit 65. In this case, a photo reflector is used as the optical sensors 66A and 66B.

  8 and 9 are explanatory diagrams showing the operation of the eccentric body 450. FIG. In FIG. 8 and FIG. 9, the direction of the eccentric body 450 is different. In the second state shown in FIG. 8, the eccentric body 450 is on the opposite side of the leaf spring 400 across the rotation shaft 452, and the eccentric body 450 and the leaf spring 400 are not in contact with each other. In the first state shown in FIG. 9, the eccentric body 450 is between the rotating shaft 452 and the leaf spring 400, and the eccentric body 450 and the leaf spring 400 are in contact with each other. The two states of FIGS. 8 and 9 can be changed from each other by rotating the eccentric body 450 around the rotation axis 452. In the case of assisting a finger operation using the finger assist unit 1001, the eccentric body 450 is set to the second state shown in FIG.

  In the second state of FIG. 8, when the control device freezes and power supply to the piezoelectric vibrating body 100 is stopped, the piezoelectric driving device 10 is in a state where the protrusion 20 is pressed by the first driven body 50 (rotor 50). Stops. In such a case, the first driven body 50 is locked by the frictional force between the protrusion 20 and the first driven body 50 (rotor 50), and the first driven body 50 cannot be rotated. For example, the finger assist device 1000 may be locked while the finger is bent, and it may be difficult to remove the finger assist device 1000 from the finger. Here, the user rotates the eccentric body 450 with a screwdriver until the first state shown in FIG. 9 is reached. In this state, since the protrusion 20 and the first driven body 50 are separated from each other, there is nothing to lock the first driven body 50, and the first driven body 50 can freely rotate. . Therefore, even if the control device freezes and power supply to the piezoelectric vibrating body 100 stops, the finger assist device 1000 can be removed from the finger. In the above embodiment, in the first state shown in FIG. 9, the protrusion 20 and the first driven body 50 are completely separated from each other. Need not be completely separated. If the second portion 420 of the leaf spring 400 and the diaphragm 200 are moved to the right as much as shown in FIG. 8, the pressing force between the protrusion 20 and the first driven body 50 is reduced. If the pressing force is reduced, the force for rotating the first driven body 50 can be reduced with a relatively weak force.

  In the first embodiment, the shape of the eccentric body 450 is circular as shown in FIGS. 8 and 9, but the shape of the eccentric body 450 may be, for example, an ellipse or an egg.

  As described above, according to the first embodiment, the piezoelectric driving device 10 includes the driving unit (the piezoelectric vibrating body 100, the vibration plate 200, and the leaf spring 400) including the piezoelectric body (piezoelectric element 110), and the protrusion 20 of the driving unit. And a driven part (first driven body 50) that can come into contact with the movable part (eccentric body 450) that contacts the leaf spring 400 of the driving part. The eccentric body 450 is in the first state shown in FIG. 8 and the second state shown in FIG. 8, in the first state, the pressing force from the protrusion 20 of the driving unit to the first driven body 50 is reduced, and in the second state, the protrusion of the driving unit The pressing force from the unit 20 to the first driven body 50 is not reduced. As a result, when the control unit of the piezoelectric driving device 10 freezes and power is no longer supplied to the piezoelectric element, the protrusion 20 is pressed against the first driven body 50 to lock. However, if the eccentric body 450 is rotated to the first state shown in FIG. 9, the first driven body 50 can be rotated. The protrusion 20 and the first driven body may be completely separated from each other. The piezoelectric driving device 10 can be applied to the finger assist device 1000 as described above. In this case, even if the control unit of the finger assist device 1000 freezes, if the eccentric body 450 is rotated to the first state shown in FIG. 9, the first driven body 50 is rotated and the finger assist device is turned from the finger. 1000 can be removed.

  Further, according to the first embodiment, the diameter of the disk 64 of the encoder 601 is smaller than the diameter of the first driven body 50 and the diameters of the large diameter gears 52 and 54 of the speed reducer 501. One finger assist part 1001 can be made small. In addition, since the piezoelectric driving device 10 is used as a driving device for the first finger assist unit 1001, no magnet or coil is required, and the first finger assist unit 1001 can be made small. Furthermore, since the rotational speed of the disc 64 is made larger than the rotational speed of the first driven body 50 using a speed increasing device composed of a plurality of gears 60, 61, 62, 63, the resolution of the encoder 601 Can be increased.

-Another embodiment of a movable part FIG. 10: is explanatory drawing which shows embodiment using the slide member instead of the eccentric body. The slide member 460 has a protrusion 462. The protrusion 462 is in contact with the second portion 420 of the leaf spring 400. FIG. 10A corresponds to the second state. FIG. 10B corresponds to the first state, and the protrusion 20 and the first driven body 50 are separated from each other. The protrusion 465 functions as an input unit that receives external force. That is, it is possible to transition between the first state and the second state by sliding the protrusion 465. In the first embodiment, the eccentric body 450 is rotated using a tool such as a screwdriver, for example. However, in this embodiment, since the sliding operation is performed, for example, a finger is used without using another tool or the like. And can be easily slid. That is, it is possible to easily switch between the first state and the second state.

-Still another embodiment of movable part FIG. 11: is explanatory drawing which shows embodiment using the pushbutton switch 470 instead of the eccentric body. The push button switch 470 has a substantially truncated cone shape, and the second portion of the leaf spring 400 is in contact with the conical surface 472. FIG. 11A corresponds to the second state, in which the great circle 474 side of the conical surface 472 is in contact with the second portion 420 of the leaf spring 400. FIG. 11B corresponds to the first state, and the small circle 476 side of the conical surface 472 is in contact with the second portion 420 of the leaf spring 400. In addition, the lower figure of FIG. 11 (A) (B) is each 11x-11x cross section of the upper figure of FIG. 11 (A) (B). Each time the push button switch 470 is pressed from the great circle 474 side, the first state and the second state can be switched alternately. That is, the push button switch 470 functions as an input unit that receives external force. In the first embodiment, the eccentric body 450 is rotated by using a tool such as a screwdriver, for example. However, in this embodiment, since the push button switch 470 is simply pressed, for example, other tools or the like are not used. In addition, the push button switch 470 can be easily switched between the first state and the second state by using a finger.

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

  FIG. 12 is an explanatory diagram showing an example of a robot 2050 that uses the piezoelectric driving device 800 described above. The robot 2050 includes a plurality of link portions 2012 (also referred to as “link members”) and an arm 2010 (“a” that includes a plurality of joint portions 2020 that connect the link portions 2012 in a rotatable or bendable state. It is also called “arm”. Each joint portion 2020 includes the above-described piezoelectric drive device, and the joint portion 2020 can be rotated or bent by an arbitrary angle using the piezoelectric drive device. 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 drive device 800, and the piezoelectric drive device 800 can be used to open and close the gripping unit 2003 to grip an object. Further, a piezoelectric drive device 800 is also provided between the robot hand 2000 and the arm 2010, and the robot hand 2000 can be rotated with respect to the arm 2010 using the piezoelectric drive device 800.

  FIG. 13 is an explanatory diagram of the wrist portion of the robot 2050 shown in FIG. The wrist joint portion 2020 sandwiches the wrist rotating portion 2022, and the wrist link portion 2012 is attached to the wrist rotating portion 2022 so as to be rotatable around the central axis O of the wrist rotating portion 2022. . The wrist rotation unit 2022 includes a piezoelectric driving device 800, and the piezoelectric driving device 800 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 800 is mounted on the base portion of the grip portion 2003. For this reason, by operating the piezoelectric driving device 800, the gripping unit 2003 can be moved to grip the object. In such a robot 2050, when the control unit freezes while gripping an object, the gripping part 2003 is locked so that the object does not fall. On the other hand, if the gripping part 2003 is locked, the object may not be removed from the gripping part 2003. However, if the piezoelectric driving device 10 described above is used as a driving device for the gripping unit 2003, the gripping unit 2003 can be moved even after the gripping unit 2003 is locked by rotating the eccentric body 450, and the object is gripped by the gripping unit 2003. It becomes possible to remove from.

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

DESCRIPTION OF SYMBOLS 10 ... Piezoelectric drive device 20 ... Protrusion part 50 ... Rotor (1st to-be-driven body)
51, 52, 53, 54, 55 ... gear 59 ... second driven body 60, 61, 62, 63 ... gear 64 ... disk 65 ... slit 66A, 66B ... optical sensor 100 ... piezoelectric vibrator 110, 110a, 110b 110e ... piezoelectric element 120 ... substrate 130 ... first electrode 140 ... piezoelectric body 150 ... second electrode 150a, 150b, 150e ... conductor layer (second electrode)
151, 152 ... wiring 200 ... diaphragm 210 ... vibrating body portion 211 ... first surface 212 ... second surface 220 ... connection portion 230 ... mounting portion 240 ... screw 300 ... drive circuit 310 ... wiring 400 ... leaf spring 410 ... first Part 420 ... Second part 430 ... Third part 450 ... Eccentric body 452 ... Rotating shaft 454 ... Groove 460 ... Sliding member 462 ... Protrusion 470 ... Push button switch 472 ... Conical surface 474 ... Great circle 476 ... Small circles 501 and 502 , 503 ... Reducer 601, 603 ... Encoder 700 ... Finger 701, 702 ... Finger support part 703 ... Band 1000 ... Finger assist device 1001, 1001a ... First finger assist part 1002 ... Second finger assist part 1003 ... Base member O 1, O 2, O 3, O 4, rotation axis Lx, outer edge PG 1, first piezoelectric element group PG 2, second Electric element groups PG3 ... third piezoelectric element group

Claims (8)

A drive unit having a piezoelectric body;
A driven part that can contact the driving part;
A movable part that can come into contact with the drive part,
The movable part is
Having a first state and a second state;
The pressing force from the driving unit to the driven unit in the first state is smaller than the pressing force from the driving unit to the driven unit in the second state.
Piezoelectric drive device. The piezoelectric drive device according to claim 1,
In the first state, the movable portion separates the driving portion and the driven portion from each other. In the piezoelectric drive device according to claim 1 or 2,
The movable part is
An input unit for receiving external force;
A piezoelectric driving device capable of transitioning between the first state and the second state in response to the external force. In the piezoelectric drive device according to any one of claims 1 to 3,
The piezoelectric driving device, wherein no electric power is applied to the piezoelectric body, and the driving unit and the driven unit are in contact with each other when the movable unit is in the second state. In the piezoelectric drive device according to any one of claims 1 to 4,
The movable unit is a piezoelectric drive device that is either an eccentric body or a slide member. The piezoelectric driving device according to any one of claims 1 to 5,
A first driven body that is rotated by the piezoelectric driving device and has a circular shape;
A decelerator that decelerates the rotation of the first driven body;
A second driven body connected to the speed reducer and assisting finger movement;
A finger assist device. The finger assist device according to claim 6, wherein
A finger assist device including an encoder.   A robot comprising the piezoelectric drive device according to any one of claims 1 to 5.

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