JP2016077792A - Finger joint driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized finger joint driving device.SOLUTION: A finger joint driving device comprises: a driving device; a first driven body being rotated by the driving device and having a circular shape; and an encoder. The encoder includes: a disc rotating in accordance with rotation of the first driven body and having a slit or a reflector; and a detector capable of detecting the slit or the reflector. A diameter of the disc is less than a diameter of the first driven body.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a finger joint drive device.

  A finger joint driving device provided with an encoder for detecting the rotation angle of the finger joint is known (for example, Patent Document 1).

JP 2008-066782 A

  In order to control the finger joint drive device with high accuracy, it is required to increase the detection accuracy of the rotation angle of the finger joint. Therefore, it is preferable to further increase the resolution of the encoder. Here, as a method for increasing the resolution of the encoder, it is common to enlarge the slit plate of the encoder. However, when the slit plate is enlarged, there is a problem that the finger joint drive device is enlarged and the action of the wearer of the finger joint drive device is restricted such that the hand cannot be put into a narrow gap. The finger joint drive device is required to be downsized, and the configuration of an encoder that can cope with downsizing has not been sufficiently studied.

  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 an aspect of the present invention, a finger joint driving device is provided. The finger joint driving device includes a driving device, a first driven body that is rotated by the driving device and has a circular shape, and an encoder. The encoder responds to the rotation of the first driven body. And a disc having a slit or a reflector, and a detector capable of detecting the slit or reflector, and the diameter of the disc is the diameter of the first driven body. Smaller than. According to this aspect, since the diameter of the disk of the encoder is made smaller than the diameter of the first driven body, the encoder can be reduced in size, and the finger joint drive device can also be reduced in size.

(2) In the finger joint drive device according to the above aspect, the finger joint drive device is disposed between the first driven body and the disk, and the rotational speed of the disk is made faster than the rotational speed of the first driven body. May be. According to this embodiment, the resolution of the encoder can be increased.

(3) In the finger joint drive device according to the above aspect, the drive device may be a piezoelectric drive device. According to this embodiment, since the driving device is a piezoelectric driving device, no magnets or coils are required, and the finger joint driving device can be downsized.

(4) The finger joint drive device according to the above aspect includes: a speed reducer that decelerates the rotation of the first driven body; and a second driven body that is connected to the speed reducer and assists the movement of the finger. May be. According to this aspect, the torque of the second driven body can be increased and backlash can be suppressed.

(5) In the finger joint drive device according to the above aspect, the diameter of the disc is smaller than the largest gear of the speed reducer, and the disc from any one of the directions along the rotation axis of the speed reducer gear. The disk may be arranged at a position hidden in the gear of the speed reducer. According to this aspect, the encoder disk does not protrude from the outer edge of the gear of the speed reducer, so that the finger joint drive device can be made compact.

  The present invention can be realized in various forms, for example, in various forms such as an encoder in the finger joint drive apparatus, an encoder arrangement method in the finger joint drive apparatus, in addition to the finger joint drive apparatus. Can do.

Explanatory drawing which shows the finger joint drive device 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 joint drive 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 joint drive device from the finger side. Explanatory drawing which shows the structure of the 3rd finger joint drive apparatus used in 2nd Embodiment. Explanatory drawing which shows the structure of the encoder in 2nd Embodiment.

First embodiment:
FIG. 1 is an explanatory diagram illustrating a finger joint driving apparatus 1000 according to the first embodiment. The finger joint driving device 1000 includes a first finger joint driving device 1001, a second finger joint driving device 1002, and a base member 1003. The first finger joint driving device 1001 is attached to the middle phalanx portion 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 joint drive device 1002 is connected to the first finger joint drive device 1001 and is attached to the proximal phalanx portion of the finger 700, and at the joint between the proximal phalanx and the metacarpal bone, Assist 700 exercises. The base member 1003 is connected to the second finger joint driving device 1002 and is attached to the back of the hand.

  The first finger joint drive device 1001 includes the piezoelectric drive device 10, a speed reducer 501, a finger support unit 701, and a band 703. The second finger joint drive device 1002 includes the piezoelectric drive device 10, a speed reducer 502, a finger support unit 702, and a band 704. The first finger joint drive device 1001 and the second finger joint drive device 1002 have substantially the same configuration. The band 703 fixes the first finger joint driving device 1001 from the ventral side of the finger 700. The band 704 fixes the second finger joint driving device 1002 from the ventral side of the finger 700. In the present embodiment, the two finger joint driving devices 1001 and 1002 are provided, but three finger joint driving devices may be provided. In this case, the third finger joint drive device is attached to, for example, the distal phalanx portion of the finger 700. Moreover, the structure provided with only one finger joint drive device may be sufficient. In this case, the finger joint driving device 1000 may include only the second finger joint driving device 1002 attached to the proximal phalanx portion of the finger 700.

  Since the second finger joint driving device 1002 and the first finger joint driving device 1001 have the same configuration except for the presence or absence of the band 703, the first finger joint driving device 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 joint driving 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 joint drive device 1000 is attached to the thumb side, the finger joint drive device 1000 of the index finger interferes with the finger joint drive device or thumb attached to the thumb. It is because there is a possibility of doing. 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 joint drive device:
FIG. 6 is a schematic view of the piezoelectric driving device and the speed reducer of the first finger joint driving device 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 joint driving device 1001 as viewed from the finger side. The first finger joint driving device 1001 includes a first driven body 50 (rotor 50), a second driven body 59, and an encoder 601 in addition to the piezoelectric driving device 10 and the speed reducer 501. 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 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 joint drive device 1002. When the first piezoelectric driving device 10 rotates the first driven body 50 by driving the first finger joint driving device 1001, the gear 52, the gear 54, and the gear unit are moved from the first driven body 50. The rotation speed decreases in the order of 59 g. 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. Moreover, the finger joint drive device 1000 can suppress the backlash by including the speed reducer 501.

  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. As a result, a large reduction ratio can be obtained, and the size of the reduction gear 501 in the height direction can be reduced, so that the size of the first finger joint driving device 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 joint driving device 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.

  As described above, according to the first embodiment, the diameter of the disc 64 of the encoder 601 is smaller than the diameter of the first driven body 50 and the diameters of the large gears 52 and 54 of the speed reducer 501. 1 finger joint drive device 1001 can be made small. Further, since the piezoelectric driving device 10 is used as the driving device of the first finger joint driving device 1001, no magnet or coil is required, and the first finger joint driving device 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.

Second embodiment:
FIG. 8 is an explanatory diagram showing the configuration of the first finger joint drive device 100a1 used in the second embodiment. The first finger joint drive device 1001a of the second embodiment can be used instead of the first finger joint drive device 1001 or the second finger joint drive device 1002 of the first embodiment.

  The first finger joint driving device 1001a differs from the first finger joint driving device 1001 in the following points. The speed reducer 503 further includes two gears 56 and 57 as compared with the speed reducer 501. The gear 56 is a gear that meshes with the gear 55 and is a large-diameter gear having a diameter larger than the diameter of the gear 55. As a result, the rotation speed of the gear 56 is smaller than the rotation speed of the gear 55. The gear 57 is a gear having the same rotation axis O <b> 4 as the gear 56, and is a small diameter gear having a diameter smaller than the diameter of the gear 56. The rotation speed of the gear 57 and the rotation speed of the gear 56 are the same. The gear 57 meshes with the gear portion 59g. The gear portion 59g has an arc shape, and the curvature of the gear portion 59g is smaller than the curvature of the gear 57. As a result, the rotation speed of the gear portion 59g is smaller than the rotation speed of the gear 57. In the reduction gear 501 of the first finger joint driving device 1001, the three rotation axes O1, O2, and O3 are on a substantially straight line, but the first finger joint driving device 1001a of the second embodiment. In the reduction gear 503, the rotation axes O1, O2, O3, and O4 are arranged at the vertices of a rhombus or a rectangle. Further, the disc 64 is disposed on the inner side of a virtual outer edge Lx obtained by extending the upper end of the uppermost large gear 54 in the direction of the piezoelectric driving device 10. In the present embodiment, the back side of the finger is referred to as “upper” or “upper side”, and the abdomen side is referred to as “lower” or “lower side”. As a result, the size of the finger 700 in the length direction can be reduced, and the size of the first finger joint driving device 1001a can be reduced.

  FIG. 9 is an explanatory diagram illustrating a configuration of the encoder 603 according to the second embodiment. The encoder 603 includes gears 67 and 68, a disc 64, and optical sensors 66A and 66B. The gear 67 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 rotational speeds of the first driven body 50 and the gear 67 are the same. The gear 68 is a gear that meshes with the gear 67 and is a very small diameter gear having a diameter smaller than the diameter of the gear 67. Therefore, the rotation speed of the gear 68 is larger than the rotation speed of the gear 67. The disc 64 has the same rotation axis O <b> 5 as the gear 68. The rotational speed of the disc 64 is the same as the rotational speed of the gear 68. The gears 67 and 68 constitute a speed increaser that makes the rotational speed of the disc 64 larger than the rotational speed of the first driven body 50. The disc 64 has a slit 65 formed along the circumference. Since the configuration of the disc 64, the slit 65, and the optical sensors 66A and 66B is the same as that of the first embodiment, further description thereof is omitted.

  As described above, also according to the second embodiment, the speed reducer 503 can be reduced, and the size of the first finger joint driving device 1001a can be reduced. In addition, according to the second embodiment, since the size of the finger 700 in the length direction of the first finger joint driving device 1001a can be reduced, the finger joint driving device 1000 can be applied to a short finger like a thumb. Can be installed.

  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, 56, 57 ... gear 59 ... second driven member 59g ... gear portion 60, 61, 62, 63 ... gear 64 ... disc 65 ... slit 66A, 66B ... optical sensor 67 ... Gear 68 ... Gear (Kana)
DESCRIPTION OF SYMBOLS 100 ... Piezoelectric vibrating body 110, 110a, 110b, 110e ... Piezoelectric element 120 ... Board | substrate 130 ... 1st electrode 140 ... Piezoelectric body 150 ... 2nd electrode 150a, 150b, 150e ... Conductor layer (2nd electrode)
151, 152 ... wiring 200 ... diaphragm 210 ... vibrating body part 211 ... first surface 212 ... second surface 220 ... connection part 230 ... mounting part 240 ... screw 300 ... drive circuit 310 ... wiring 501, 502, 503 ... speed reducer Reference numerals 601 and 603 are encoders 700 are fingers 701 and 702 are finger support portions 703 and 704 are bands 1000 are finger joint drive devices 1001 and 1001a are first finger joint drive devices 1002 are second finger joint drive devices 1003 are base members O 1, O 2, O 3, O 4, rotation axis Lx, outer edge PG 1, first piezoelectric element group PG 2, second piezoelectric element group PG 3, third piezoelectric element group

Claims (5)

A driving device;
A first driven body rotated by the driving device and having a circular shape;
An encoder,
With
The encoder is
A disc that rotates according to the rotation of the first driven body and has a slit or a reflector;
A detector capable of detecting the slit or reflector;
Have
A diameter of the disc is smaller than a diameter of the first driven body;
Finger joint drive device. The finger joint drive device according to claim 1,
A finger joint drive device, comprising: a speed increasing device that is disposed between the first driven body and the disk and that makes the rotational speed of the disk faster than the rotational speed of the first driven body. The finger joint drive device according to claim 1 or 2,
The finger joint drive device, wherein the drive device is a piezoelectric drive device. In the finger joint drive device according to any one of claims 1 to 3,
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 joint drive device comprising: In the finger joint drive device according to claim 4,
The diameter of the disc is smaller than the diameter of the largest gear among the gears of the reducer,
The finger joint drive device, wherein the disk is disposed at a position hidden by the gear of the speed reducer when the disk is viewed from either one of the directions along the rotation axis of the gear of the speed reducer.

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