JP2007135268A - Stator of ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator which can enhance the efficiency of an ultrasonic motor while increasing the torque. <P>SOLUTION: In an ultrasonic motor comprising a stator for forming a traveling wave by a plurality of piezoelectrics bonded to a resilient body, and a rotor and arranged to rotate the rotor by bringing it into pressure contact with the traveling wave formation side of the stator, a plurality of comb teeth are provided in the circumferential direction of the stator, and the comb teeth are formed by a plurality of slits provided at a predetermined angle to a normal on the circumference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stator used for a vibrating body such as an ultrasonic motor.

  2. Description of the Related Art Conventionally, an ultrasonic motor that can drive a rotor in contact with a stator by vibration of a piezoelectric element on the stator side without using magnetic force has been developed.

  Ultrasonic motors can be used for various purposes by devising the number of stators and the shape of the rotor. For example, disk-type and ring-type rotors are already well known. Recently, development of a spherical ultrasonic motor having a rotor as a sphere has also been advanced.

  A stator of such an ultrasonic motor is formed by, for example, polarizing a predetermined portion of a flat plate-shaped piezoelectric element in a predetermined direction to form an A phase and a B phase as piezoelectric element members. A traveling wave is generated in the elastic body to which the piezoelectric element member is fixed by applying a predetermined voltage to the drive electrode provided for each phase. The rotor is brought into pressure contact with the traveling wave forming surface, and the rotor is rotated by friction.

  Patent Documents 1 and 2 disclose the shape of comb teeth of a stator of a conventional ultrasonic motor. The structure of this conventional stator will be described below with reference to the drawings.

  8A and 8B are views showing a stator of a conventional ultrasonic motor, in which FIG. 8A is a plan view seen from the direction in which the rotor contacts, and FIG. 8B is a side sectional view of a comb tooth portion.

  As shown in FIG. 8A, a large number of comb teeth 233 are provided on the rotor contact surface of the stator 203b along the circumference of the stator 203b. A ring-shaped piezoelectric element member is fixed to the back surface of the stator, and is repeatedly expanded and contracted by application of an alternating voltage, and a traveling wave is generated in the circumferential direction of the stator.

  The comb teeth 233 have an effect of expanding the vibration amplitude in the rotation direction of the rotor in order to efficiently rotate the rotor (not shown) that is in pressure contact with the convex portions of the comb teeth.

  In the conventional ultrasonic motor stator 203b, as shown in FIGS. 8 (a) and 8 (b), a plurality of slits 233a provided radially in a direction coinciding with the normal line of the circumference of the disk-shaped stator 203b. Thus, the comb teeth 233 are formed.

Japanese Patent Laid-Open No. 7-80793 JP 2000-270569 A

  Conventionally, in an ultrasonic motor, it has been a problem to increase the torque by improving the efficiency.

  The present invention has been made in view of the above points, and it is possible to improve the efficiency of the ultrasonic motor and increase the torque by improving the shape of the comb teeth that greatly affect the vibration amplitude of the stator and the slits that form the comb teeth. An object is to provide a stator.

  The present invention includes a stator that forms a traveling wave by a plurality of piezoelectric bodies fixed to an elastic body, and a rotor, and is configured to rotate by bringing the rotor into pressure contact with the traveling wave forming surface of the stator and rotating the rotor. In the stator of a sonic motor, a plurality of comb teeth are provided in the circumferential direction of the stator, and the comb teeth are formed by a plurality of slits provided at a predetermined angle with a normal line on the circumference. And

  According to the present invention, since the length of the comb teeth is increased, the amplitude is increased and the torque of the ultrasonic motor can be increased.

  Further, according to the present invention, since the slits on the stator surface are inclined in the circumferential direction, the rigidity in the circumferential direction can be made uniform, and the traveling wave can be stabilized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a spherical ultrasonic motor according to an embodiment of the present invention.

  In the present embodiment, a case of a spherical ultrasonic motor in which the rotor is a sphere will be described. However, the stator of the ultrasonic motor according to the present invention can also be applied to a disk-shaped rotor.

  As shown in FIG. 1, the ultrasonic motor 1 according to the present embodiment rotates a spherical rotor 2 while being held by three stators 3 a, 3 b and 3 c provided on a frame member 4. 2 are provided on the surfaces of the stators 3a, 3b, and 3c that come into contact with the rotor 2, and the comb teeth 33 vibrate to generate traveling waves, whereby the rotor 2 rotates. Be made.

  In the present embodiment, the structures of the stators 3a, 3b, and 3c are the same. Therefore, the stator 3b will be described below as a representative.

  FIG. 2 is a plan view of the stator 3 b shown in FIG. 1 as viewed from the contact surface of the rotor 2.

  As shown in FIG. 2, a large number of comb teeth 33 are provided on the contact surface of the rotor 2 of the stator 3b along the circumference of the stator 3b. Below these comb teeth 33, a piezoelectric element member 31 shown in FIG. 3 is provided, and the piezoelectric elements of the piezoelectric element member expand and contract by voltage application to vibrate the comb teeth 33. In the ultrasonic motor 1, the rotor 2 can be rotated in an arbitrary direction by controlling this vibration.

  In the stator 3b of the present embodiment, as shown in FIG. 2, adjacent comb teeth 233 are separated radially in a direction in which the angle formed with the normal line of the circumference of the disk-shaped stator 3b is 10 °. A slit 33a is provided to form each of the plurality of comb teeth 33.

  3 is an exploded perspective view showing the stator 3b shown in FIG. 2 disassembled into an elastic body 30 and a piezoelectric element member 31. As shown in FIG.

  As shown in FIG. 3, the stator 3 b includes an elastic body 30 and a piezoelectric element member 31.

  As shown in FIG. 2, a plurality of comb teeth 33 separated by slits 33 a are provided on the surface of the elastic body 30.

  The piezoelectric element member 31 includes a flat plate-shaped piezoelectric element 36, an individual electrode 34 for polarizing a predetermined piezoelectric element piece of the piezoelectric element 36 in a predetermined direction for the A phase, and a piezoelectric element 36. Individual electrodes 35 for causing the predetermined piezoelectric element pieces to be polarized in a predetermined direction for the B phase, drive electrodes 38 for driving the A phase piezoelectric element pieces, and driving the B phase piezoelectric element pieces. Drive electrode 37, an individual electrode 50 for polarizing a predetermined piezoelectric element piece of the piezoelectric element 36 in a predetermined direction for vibration detection, and a piezoelectric element piece below the individual electrode 50 by vibration of the piezoelectric element 36 Vibration detection electrode 51 for detecting the potential generated by the voltage, wiring 40 for applying voltage to the A-phase driving electrode 38, wiring 41 for applying voltage to the B-phase driving electrode 37, and vibration detection For detecting potential from the electrode 51 Configured to have a wiring 42.

  The individual electrode 34, the individual electrode 35, the individual electrode 50, the vibration detection electrode 51, the drive electrode 37, and the drive electrode 38 are, for example, silver electrodes, and each of the wiring 40, the wiring 41, and the wiring 42 is, for example, soldered. 40 is connected to the drive electrode 38, the wiring 41 is connected to the drive electrode 37, and the wiring 42 is connected to the vibration detection electrode 51.

  4A and 4B are views showing the structure of the piezoelectric element member 31 of the stator 3b shown in FIG. 3, wherein FIG. 4A is a perspective view of the piezoelectric element member 31, and FIG. 4B is a dotted line. It is the perspective view which rotated with the axis | shaft XX and was seen from the back, (c) is a partially broken perspective view which fractures | ruptures and shows a part of (a).

  As shown in FIGS. 4A to 4C, in the piezoelectric element member 31, a part of the flat plate annular piezoelectric element 36 in the circumferential direction is an A phase, and another part of the circumferential direction is a B phase. The A phase and the B phase are driven with their phases shifted in time to generate a traveling wave of vibration.

  FIG. 5 is a plan view showing the polarization direction of the piezoelectric element member 31 of the present embodiment shown in FIG.

  As shown in FIG. 4A, in the piezoelectric element member 31 of the present embodiment, the left side portion in the circumferential direction is the A phase, and the piezoelectric element pieces whose polarization directions are opposite in the A phase are alternately arranged. For example, it is provided with an angle of 36 °, and the right side portion in the circumferential direction is the B phase, and the piezoelectric element pieces whose polarization directions are reversed in the B phase are alternately set at an angle of, for example, 36 °. Is provided. Further, as shown in FIG. 5, the A phase and the B phase are configured to be shifted by 18 °, for example.

  FIG. 6 is a diagram showing experimental results of measuring the torque of the ultrasonic motor.

  6 shows the torque of the conventional stator shown in FIGS. 8A and 8B and the stator of the present embodiment shown in FIG. 2, and the pressing force for pressing the rotor against the stator is 1 kg in each case. The torque in the case of the case and 1.5 kg is shown.

  As can be seen with reference to FIG. 6, in both cases where the pressing force is 1 kg and 1.5 kg, the slits 233a on the stator surface and the stator 203b are shown in FIGS. 8 (a) and 8 (b). The angle formed between the slit 33a on the stator surface and the circumferential normal line of the stator 3b as shown in FIG. 2 is larger than the case where the angle formed with the circumferential normal line is 0 ° (shown as 0 ° in FIG. 6). In the case of 10 ° (shown as 10 ° in FIG. 6), a larger torque was obtained.

  By the way, in the embodiment shown in FIG. 2, the angle formed by the slit on the stator surface and the normal line of the circumference of the stator is 10 °, but the present invention is not limited to this, and it can be changed according to necessity. Can be an angle. An example of this is shown in FIG.

  FIG. 7 is a plan view showing another example of the stator according to the present invention different from FIG.

  As shown in FIG. 7, in the stator 103b of this example, slits that separate adjacent comb teeth 133 in a radial direction in a direction where the angle formed with the normal line of the circumference of the disk-shaped stator 103b is 30 °. 133a is provided, and thereby each of the plurality of comb teeth 133 is formed. The present invention can be configured as shown in FIG.

1 is a perspective view schematically showing a spherical ultrasonic motor according to an embodiment of the present invention. FIG. 2 is a plan view of the stator 3b shown in FIG. FIG. 3 is an exploded perspective view showing a stator 3b shown in FIG. 2 in an exploded manner with an elastic body 30 and a piezoelectric element member 31. It is a figure which shows the structure of the piezoelectric element member 31 of the stator 3b shown in FIG. 3, (a) is a perspective view of the piezoelectric element member 31, (b) is the axis XX which shows (a) with a dashed-dotted line. It is the perspective view seen from the back by rotating in (c), (c) is the partially broken perspective view which fractures and shows part of (a). It is a top view which shows the polarization direction of the piezoelectric element member 31 of this Embodiment shown to Fig.4 (a). It is a figure which shows the experimental result which measured the torque of the ultrasonic motor. It is a top view which shows the example different from FIG. 2 of the stator by this invention. It is a figure which shows the stator of the conventional ultrasonic motor, (a) is the top view seen from the direction which a rotor contacts, (b) is a sectional side view of a comb-tooth part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Position detection apparatus 2 Rotor 3a, 3b, 3c Stator 4 Frame member 30 Elastic body 31 Piezoelectric element member 33 Comb tooth 33a Slit 34, 35 Fixed electrode 36 Piezoelectric element 37, 38 Drive electrode 40, 41 Wiring

Claims (2)

A stator for an ultrasonic motor, comprising: a stator that forms a traveling wave with a plurality of piezoelectric bodies fixed to an elastic body; and a rotor, wherein the rotor is rotated in pressure contact with the traveling wave forming surface of the stator. In
An ultrasonic motor comprising a plurality of comb teeth in a circumferential direction of the stator, and the comb teeth are formed by a plurality of slits provided at a predetermined angle with a normal line on the circumference. Stator.   An ultrasonic motor comprising the stator according to claim 1, wherein the rotor is driven by the stator.

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