JPS63206173A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To detect movement at high precision and lower a cost, by providing a moving unit with a sensor confronted with a stationary unit, and by sequentially detecting the individual projections of a pectinate section with the sensor when the moving unit is in motion. CONSTITUTION:A stator base metal 11 is formed in the shape of a ring, and on the back side surface, a piezoelectric unit (electrostrictive element) 12 is fitted to compose a stator (stationary unit) 10. On the base metal 11, projections 13 are arranged in the circumferential direction (progressive direction of progressive wave). Besides, a rotor base metal 21 is formed in the shape of a ring having a width smaller than that of the stator base metal 11, and on the back side surface of the metal 21, a slider 22 is fitted to compose a rotor (moving unit) 20. From the rotor base metal 21, internal and external arms 211, 212 project. An internal arm tip section 211a is provided with a luminous element 31, and an external arm tip section 212a is provided with a light receiving element 32, and via a groove 14 between said projections 13, the generated light of the luminous element 31 is received by the light receiving element 32. Then, along with the driving of the rotor 20, said projections 13 are sequentially detected, and the moving speed and the like of a motor can be determined by the number of pulses and the period.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to an ultrasonic motor that drives a moving object using progressive vibration waves formed in a fixed body using a piezoelectric material, and particularly to an ultrasonic motor that has a built-in movement detection sensor. Regarding.

B. Prior art This type of ultrasonic motor, for example a rotary ultrasonic motor, is
As shown in FIGS. 9(a) and 9(b), a movable body 72 having the same shape is pressed against an annular fixed body 71 with a predetermined pressing force by a spring member or the like (not shown). A piezoelectric body 73 is attached to the back surface of the fixed body 71, and segment electrodes 74a to 74d are formed on the surface of the piezoelectric body 73. The piezoelectric bodies 73 under segment electrodes 74b and 74d are alternately polarized. When the segment electrode 74a is grounded and high frequency electrical signals with a phase shift of 90 degrees are supplied to the segment electrodes 74b and 74d, the piezoelectric body 73
vibrates, thereby forming a progressive vibration wave in the fixed body 71 and rotationally driving the movable body 72.

Position detection of this type of ultrasonic motor is known, for example, from Japanese Patent Application Laid-open No. 60
As disclosed in Japanese Patent No. 113675, a through hole is formed in the thickness direction of a rotor that is a moving body, and a light emitting device is placed on one side of the through hole and a light detecting device is placed on the other side, This is done based on pulses output from a photodetector in accordance with the rotation of the rotor.

On the other hand, various ultrasonic motors aiming at higher efficiency have been proposed, for example, in Japanese Patent Application Laid-open No. 102177/1982,
A device is disclosed in which the progressive vibration waves formed in the fixed body also form the progressive vibration waves in the moving body. Also,
Nikkei Electronics March 24, 1986 issue P90
92 discloses an ultrasonic motor shown in FIG. This has a plurality of comb-teeth-like protrusions 82 on one surface of a fixed body 81 in the direction of propagation of progressive vibration waves, and a movable body 83 is brought into pressure contact with the comb-teeth-like protrusions 82. shaped protrusion 8
The moving body 83 is driven by the movement of 2. Note that 84 is a piezoelectric body and 85 is a slider.

Problems to be Solved by the C0 Invention In order to accurately detect the position of the highly efficient ultrasonic motor mentioned above, it is necessary to drill a large number of highly accurate through holes in the moving body, which reduces the processing cost. In addition, it is difficult to design the vibration state of the moving body of this type of high-efficiency ultrasonic motor, and it becomes even more difficult to obtain the optimum vibration state by drilling a large number of through holes.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic motor that can accurately detect movement without affecting the efficiency of the ultrasonic motor that has comb-like protrusions.

The present invention will be explained with reference to FIG. 1 showing an embodiment of a means for solving the D0 problem. The ultrasonic motor according to the present invention has a plurality of It has a fixed body 10 having a comb-teeth-like protrusion 13, and a movable body 2o that is brought into pressure contact with the plurality of comb-teeth-like protrusions 13 and is driven by the traveling wave generated in the comb-teeth-like protrusion 13. However, the above-mentioned problem can be solved by providing the sensors 31 and 32 on the movable body 20, and when the movable body 20 moves over the plurality of comb-like projections 13, the sensors 31 and 32 are disposed on the movable body 20.
1 and 32 are solved by sequentially detecting the plurality of comb-like protrusions 13.

80 action When a progressive vibration wave is formed in the fixed body 20 by the piezoelectric body 12, the comb-like protrusions 13 amplify the vibration and the moving body 20
and drives the moving body 20.

As the movable body 2o is driven, the sensors 31 and 32 sequentially detect the comb-like protrusions 13. Therefore, since the sensor output is generated in the form of pulses, the amount of movement and speed of the ultrasonic motor can be easily detected by measuring the number and period of the pulses.

F. Example 1.First embodiment- A first embodiment will be explained with reference to FIGS. 1 and 2.

The stator base material 11 is formed in a ring shape, and a piezoelectric material (electrostrictive element) 12 is adhered to the back surface thereof, for example, as shown in FIG. 9(b), thereby forming the stator (fixed body) 10. Ru. As shown in FIG. 10, the stator base material 11 has comb-like protrusions 13 arranged in the circumferential direction, that is, in the traveling direction of the oscillatory traveling wave (hereinafter referred to as traveling wave). On the other hand, the rotor base material 21 is formed into a ring shape having a width narrower than the stator base material 11, and a slider 22 is attached to the back surface of the rotor base material 21, thereby forming a rotor (moving body) 20. Rotor base material 21
The inner arm 21 extends from
1 and an outer appearance 212 are respectively protruded. The inner arm tip 211a is provided with a light emitting element 31, and the outer arm tip 211a is provided with a light emitting element 31.
12a is provided with a light receiving element 32, and the light emitted from the light emitting element 31 is received by the light receiving element 32 through the groove 14 between the comb-like protrusions 13. Said 1
A pair of light emitting element 31 and light receiving element 32 constitute a sensor.

33 is an input/output portion provided on a fixing member (not shown), and is an input brush 33a for a light emitting element.

33b and light-receiving element output brushes 33c and 33d, each brush comes into contact with a conductive pattern (not shown) formed on the surface of the rotor base material 21, and slides on the pattern as the rotor 20 rotates. The conductive pattern is the inner arm 211.
Also formed on the outer arm 212, the input brushes 33a, 33b and the light emitting element 31 are electrically connected, and the output brush 33c
, 33ci and the light receiving element 32 are electrically connected.

Next, the operation of this embodiment will be explained.

When a high frequency electric signal is supplied to each electrode of the piezoelectric body 12 from a drive control circuit (not shown), the piezoelectric body 12 vibrates and a traveling wave is formed in the stator base material 11.

This traveling wave is amplified by the comb-shaped protrusion 13 and the slider 22
is transmitted to the rotor base material 21 via. Rotor base material 21
rotates while vibrating in synchronization with the stator base material 11.

On the other hand, the light emitting element 31 is connected via the input brushes 33a and 33b.
When power is supplied to the light emitting element 31, the light emitting element 31 emits light.

Since the light emitted from the light-emitting element 31 travels toward the light-receiving element 32 along the illustrated path P, the light is received by the light-receiving element 32 every time the path P crosses the groove 14 between the comb-like protrusions 13. As a result, the second
A pulse signal as shown in the figure is obtained. Therefore, by counting these pulses with a counter or the like, the rotational angular position of the rotor 20 can be detected. Furthermore, by measuring the pulse interval, the rotational speed and rotational angular velocity can be detected.

In addition, the inner arm 211. The mounting position of the outer arm 212 is the rotor 2
Any location is fine as long as it does not interfere with the 0 rotation.

1. Second Embodiment - FIG. 3 shows a second embodiment. The basic configurations of the stator 10 and rotor 20 are the same as in the first embodiment, and similar parts are given the same reference numerals and only the differences will be explained.

A light emitting element 31 is provided on the lower surface of an inner arm 211 protruding from the rotor 20 toward the rotation center, and a light receiving element 32 is provided on the lower surface of the outer shell 212 protruding outward from the rotor 20.
The light emitted from the light emitting element 31 is reflected by the groove bottom 15 between the comb-like protrusions 13 as indicated by a path P, and is incident on the light receiving element 32. The pair of light emitting element 31 and light receiving element 32 constitute a sensor. Therefore, when both arms 211 and 212 face the top 16 of the comb-like protrusion 13, no light enters the light receiving element 32. As a result, each time one pixel element 31, 32 passes through the groove 14 between the comb-like protrusions 13 in synchronization with the rotation of the rotor 2o, the output of the light receiving element becomes high level, and the pulse signal shown in FIG. 2 is obtained. .

In this embodiment, the inner arm 211. The outer arm 212 is the stator 10
Since it does not protrude from the circumferential surface of the cylinder, it is effective when radial space is limited.

-Third Embodiment- FIG. 4 shows a third embodiment. The basic configurations of the stator 10 and rotor 20 are the same as in the first embodiment, and similar parts are given the same reference numerals and only the differences will be explained.

Only the outer face 212 is provided protruding from the outer peripheral surface of the rotor base material 21, and a light emitting element 31 and a light receiving element 32 are arranged in parallel in the circumferential direction on the lower surface of the tip thereof, and the emitted light from the light emitting element 31 is directed to the path P.
As shown, the light is reflected by the top 16 of the comb-like protrusion 13 and is received by the light receiving element 32. The pair of light emitting element 31 and light receiving element 32 constitute a sensor.

Therefore, when the outer face 212 faces the groove bottom 15 between the comb-like protrusions 13, no light enters the light receiving element 32. As a result, in synchronization with the rotation of the rotor 2o, the pixel 3
1.32 confronts the top 16 of the comb-shaped protrusion 13, the output of the light receiving element becomes high level, and the pulse signal shown in FIG. 2 is obtained.

Note that the pixel elements 31 and 32 may be arranged in parallel in the radial direction.
Alternatively, the light emitted from the light emitting element 31 may be reflected by the groove bottom 14 between the comb-like protrusions 13 and enter the light receiving element 32.

This embodiment is effective when there is a space restriction inside the rotor 2o and there is also a space restriction outside the stator 10.

-Fourth Embodiment- FIG. 5 shows a fourth embodiment. The basic configurations of the stator 10 and rotor 20 are the same as in the first embodiment, and similar parts are given the same reference numerals and only the differences will be explained.

The tip of the external face 212 protruding outward from the rotor base material 21 is bent, and a light emitting element 31 and a light receiving element 32 are arranged in parallel in the circumferential direction on a surface facing the outer peripheral surface 17 of the comb-like protrusion 13 to emit light. The light emitted from the element 31 is reflected by the outer circumferential surface 17 of the comb-like protrusion 13 along the path P, and is transmitted to the light receiving element 32.
It is configured to receive light at The pair of light emitting element 31 and light receiving element 32 constitute a sensor. Therefore, the pixel elements 31 and 32 are connected to the groove 1 between the comb-like protrusions 13.
4, no light enters the light receiving element 32. As a result, the pixel 31
, 32 confronts the outer circumferential surface 17 of the comb-like protrusion 13, the output of the light receiving element 32 becomes high level, and a pulse signal shown in FIG. 2 is obtained. Note that the pixel elements 31 and 32 may be arranged side by side in the thickness direction of the rotor.

In this embodiment, there is a spatial restriction between the surface 21a of the rotor 20 and the top 16 of the comb-like protrusion 13. It is effective in some cases.

Note that in the above four embodiments, the positional relationship between the light emitting element 31 and the light receiving element 32 may be reversed. However, in the case of a camera or the like in which an optical lens system or the like is arranged inside the rotor 20, the detection light is emitted from the inside to the outside as in the first embodiment, and the optical lens system is affected by the detection light. It is preferable that there be no

In addition, 3rd. In the fourth embodiment, an inner arm is provided protruding from the inner peripheral surface of the rotor base material 21, and the pixel elements 31 and 32 are attached to the rotor 2.
It may be located on the inner diameter side of 0.

-Fifth Embodiment- FIG. 6 shows a fifth embodiment. The basic configurations of the stator 10 and rotor 20 are the same as in the first embodiment, and similar parts are given the same reference numerals and only the differences will be explained.

The stator base material 11 of this embodiment is made of a magnetic material. A magnetic sensor 41 such as a Hall element or a magnetoresistive element is provided on the lower surface of the tip of the outer shell 212 that protrudes outward from the rotor 21 .

The magnetic field formed by the stator base material 11 increases as the magnetic sensor 41 approaches the stator base material 11.
Therefore, each time the rotor 20 rotates and the magnetic sensor 41 confronts the top 16 of the comb-shaped protrusion 13 and the groove bottom 15, a detection signal in the form of a rectangular wave shown in FIG. 8 is obtained. By counting the number of repetitions of this rectangular wave, the rotational angular position of the rotor 20 is detected. Further, by measuring the period of this rectangular wave, the rotation angle and the rotation angular velocity can be detected.

The magnetic sensor 41 may be provided at a position facing the outer circumferential surface or inner circumferential surface of the comb-teeth-like protrusion 13, or an inner arm may be provided protruding from the inner circumferential surface of the rotor 20 and the tip thereof may be provided with an inner arm as shown in FIG. It may also be provided in the same way.

1. Sixth Embodiment - FIG. 7 shows a sixth embodiment. The basic configurations of the stator 10 and rotor 20 are the same as in the first embodiment, and similar parts are given the same reference numerals and only the differences will be explained.

An outer face 212 is provided protruding from the outer peripheral surface of the rotor base material 21, and a counter electrode 51 is formed on the lower surface of the outer face 212,
Opposing electrodes 52 and 53 are also formed on the top portion 16 of the comb-like protrusion portion 13 and the groove bottom portion 15, respectively. The counter electrode 51
Configure the sensor. Here, the opposing electrodes 51 and 52
The gap between the opposing electrodes 51 and 53 is d2, and the opposing area between the opposing electrodes 51 and 52, and 51 and 53 is S.
, when the dielectric constant of air is ε, the opposing electrodes 51 and 52.5
The capacitance C between 3 is as follows. Since d<dZ, the capacitance C changes in a rectangular waveform as shown in FIG. The rotation of the rotor 21 can be detected by converting the change in capacitance C into a frequency signal using, for example, a CR oscillator, and converting this into a voltage value corresponding to the frequency using an F/V converter or the like.

In addition, the position of the counter electrode 51 on the rotor side may be provided on the inner arm of the rotor 21. In addition, the counter electrode 52 on the stator side
．． 53 may be provided on the same circumferential surface of the stator.

In the above, an optical sensor, a magnetic sensor, and a capacitance sensor are used as sensors, but an ultrasonic sensor or an AE (acoustic emission) sensor may also be used.

Furthermore, in the six embodiments described above, all rotary ultrasonic motors using a ring-shaped stator and rotor were explained, but there are also motors using a disc-shaped stator and rotor, and linear ultrasonic motors using a disk-shaped stator and rotor. This invention can also be applied to motors.

G1 Effects of the Invention According to the present invention, a sensor is provided on a movable body opposite to a fixed body having comb-like protrusions protruding from the fixed body and arranged in the traveling direction of a traveling wave, and when the movable body moves, the sensor is installed. Since each of the comb-like protrusions is sequentially detected, movement can be detected with high accuracy while maintaining high efficiency as in the conventional case. It is also possible to reduce costs.

[Brief explanation of the drawing]

1 and 2 show a first embodiment, where FIG. 1 is a partial perspective view and FIG. 2 is a waveform diagram of the sensor output. 3 to 7 are partial perspective views showing second to sixth embodiments of the present invention, respectively. FIG. 8 is a waveform diagram of the sensor output of the embodiment shown in FIGS. 6 and 7. 9(a) and 9(b) show the schematic configuration of a rotary ultrasonic motor, where (a) is a plan view thereof, (b) is a sectional view taken along line bb--b, and FIG. 10 is a comb-like protrusion. FIG. 1o: Stator 11: Stator base material 12: Piezoelectric body 13: Comb tooth-shaped protrusion 14: Groove
2o: Rotor 21: Rotor base material 22
Varnish slider 31: Light emitting element 32: Light receiving element 4
1: Magnetic sensor 51-53: Opposing electrode 211: Inner arm
212: External patent applicant: Nippon Kogaku Kogyo Co., Ltd. Representative Patent Attorney Fuyu Nagai Figure 1 Rotation amount Figure 2 Figure 5 Figure q

Claims (1)

[Scope of Claims] A fixed body having a plurality of comb-like protrusions arranged in the traveling direction of a traveling wave formed by a piezoelectric body, and a fixed body having a plurality of comb-teeth-like protrusions that are brought into pressure contact with the plurality of comb-teeth-like protrusions and are caused by the traveling wave. In an ultrasonic motor having a driven moving body, a sensor is provided on the moving body, and when the moving body moves over the plurality of comb-teeth shaped protrusions, the sensor moves over the plurality of comb-shaped protrusions. An ultrasonic motor characterized by being configured to sequentially detect protrusions.