JPS63287376A - Oscillatory wave motor - Google Patents

Abstract

PURPOSE:To diminish the space and reduce the cost, by using a plurality of grooves arranged in the diameter direction, for an oscillating unit, and by forming a position detector. CONSTITUTION:An oscillatory wave motor is composed of a movable unit 1, an oscillating unit 2 having an electrostriction element, and a luminous diode photo-transistor 3 as a position detector fixed at a part of the movable unit 1. The oscillating unit 2 is provided with a plurality of oscillating pieces 2a and grooves 2b arranged in the diameter direction. As a result, when the movable unit 1 is rotated, then a case that light from said luminous diode enters the photo-transistor through the grooves 2b, and a case that the light is interrupted by the oscillating pieces 2a are alternately found, and so the output voltage signal of the photo-transistor is pulsated, and a positional detection can be performed by counting this pulse.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibration wave motor driven by progressive vibration waves, and in particular to a position detection device that uses grooves in a vibrating body without using an encoder. This is related to those that have the following.

[Prior Art] “First, the principle of a vibration wave motor that utilizes the traveling wave of bending vibration will be explained with reference to FIG. 7 showing the detection state and FIG. 8 showing the bottom side thereof. As shown in the figure, for example, a first group of electro-mechanical energy conversion elements 11a and a second group of electro-mechanical energy conversion elements ttb are arranged on the lower surface of a ring plate-shaped diaphragm 12 made of a metal elastic body. The array is fixed. These electrical-mechanical energy conversion elements include:
A piezoelectric element, a strain element, a magnetostrictive element, or the like can be used, but in the following, it will simply be referred to as a conversion element.

First, regarding the first group conversion elements 11a, electrode films (not shown) are provided on the upper and lower surfaces of all conversion elements 11a, and these electrodes are connected to each other by electrical connection means (not shown). The lower surface electrodes are electrically connected in parallel, and a voltage is simultaneously applied to each conversion element 11a, and each conversion element is configured to expand and contract in the circumferential direction by applying this voltage. Each conversion element 11a is arranged in the circumferential direction so that adjacent ones have opposite polarities, that is, as one expands, the other contracts, and with a pitch of λ/2. Arranged.

The same applies to the configuration and arrangement of the second group conversion element 11b.

The first group conversion element 11a and the second group conversion element 11b are λ/
They are arranged offset by an odd multiple of 4. Also, diaphragm 1
The total length of 2 is an integral multiple of the above entry. Note that the portion 11 between the first group conversion element 11a and the second group conversion element flb
' is a region where no voltage is applied and no active expansion or contraction occurs. In this way, the diaphragm 12 and the conversion element 11a.

11b and portion 11' form a vibrating body.

In the above-described configuration and arrangement, when an AC voltage is applied only to the first group converting element 11a, the vibrating body convexes downward in the extending converting element 11a, and the converting element 11 contracts.
As a result of the upwardly convex bending deformation in the part a, a standing wave of bending vibration occurs over the entire circumference of the vibrating body, that is,
A standing wave of wavelength λ is generated. In this case, each conversion element 11
The intermediate position between a and each position every λ/2 from there becomes a node. When an AC voltage is applied only to the second group conversion element 11b, a standing wave of wavelength λ is similarly generated, but the position of the node is shifted by λ8 compared to that of the standing wave.

At the same time as applying an AC voltage to the first group conversion element 11a,
This means that an AC voltage with a phase difference of π/2 is electrically applied to a second
When applied to the group conversion element flb, as a result of the synthesis of the standing waves of both, a traveling wave of bending vibration that travels in the circumferential direction is generated in the vibrating body, and its traveling direction is determined by the sign or negative of the phase difference of the applied voltage. . In this traveling wave of bending vibration, points on the neutral plane of the thickness of the diaphragm 12 only vibrate in the vertical direction, but points on the top and bottom surfaces of the diaphragm 12 vibrate in the vertical direction and in the circumferential direction. It performs a type of elliptical motion that is a combination of vibrations. Therefore, if the diaphragm 12 is appropriately supported so as not to rotate, and the movable body 13 of the ring plate is brought into pressure contact with the upper surface of the diaphragm 12, the movable body 13 will be moved by the frictional force caused by the elliptical motion of the diaphragm 12. It is driven to rotate, and the direction of rotation can be selected depending on the positive or negative phase difference of the voltages applied to the conversion element groups 11a and 11b. The above is the principle of a vibration wave motor that uses traveling waves of bending vibration.

In addition, the vibration wave 12 has a large number of grooves 12a in the radial direction and a vibrating piece 12 in order to obtain a vibration effect by lowering the neutral plane of the thickness.
b.

Conventionally, in such a vibration wave motor, an external encoder has been used to detect the position of the vibration wave motor.

[Problems to be solved by the invention] As mentioned above, in the past, an external encoder was required to detect the position of the vibration wave motor, which required a large amount of space and was costly. The problem was that it was expensive.

The present invention attempts to solve these problems. That is, the present invention aims to provide a vibration wave motor equipped with a position detection device that can be used in a smaller base space and at a lower cost than when a conventional external motor is installed. This is the purpose.

[Means for Solving the Problems] A position detection device is provided that detects the position by using a large number of grooves provided in the radial direction of the vibrating body.

[Function] Since the vibrating body has a large number of grooves and vibrating pieces provided in the radial direction, the rotation of the moving body causes the action of light from the light emitting diode or magnetism from the magnet to be caused by the grooves and the vibrating pieces. As a result, the output voltage signal of the phototransistor or Hall element changes in a pulsed manner, and by counting the pulses, the position of the moving object can be detected.

[Example] FIG. 1 shows a first embodiment of the invention.

In FIG. 1, 1 is a moving body, 2 is a vibrating body having an electrostrictive element, 2a is a large number of vibrating pieces provided in the radial direction of the vibrating body 2, 2b is also a groove, and 3 is a moving body as a position detection device. 1
A light emitting diode/phototransistor is fixed to a part of the

In Figure 2, the horizontal axis represents the 10 rotation angle ωt of the moving body (ω is the angular velocity,
t is time), and the vertical axis is the output voltage V of the phototransistor.

In the vibration wave motor configured as shown in FIG. When the light enters the phototransistor of the light emitting diode/phototransistor 3 through 2b, and when it is blocked by the vibrating piece 2a,
Since they appear alternately, the output voltage signal of the phototransistor becomes a pulse 1 as shown in FIG. 2, and by counting these pulses, the position can be detected.

FIG. 3 shows a second embodiment of the invention.

In FIG. 3, 4 is a non-magnetic body fixed to the moving body 1, 5 is a permanent stone bonded to the non-magnetic body 4, and 6 is fixed to the moving body 1 facing the permanent magnet 5. It is a Hall element that has been Also, what is the width of the permanent magnet 5? g 2 be equal to or less than the width of b. That is, the third
The illustrated embodiment corresponds to the case where a Hall element 6 is used in place of the light emitting diode/phototransistor 3 of the embodiment shown in FIG.

In the vibration wave motor configured as shown in FIG. 3, when the motor rotates, that is, when the moving body 1 rotates, the Hall element 6 and permanent magnet 5 (not shown) and structure 2b alternately. When the Hall element 6 is sandwiched between the permanent magnet 5 and the vibrating piece 2a, the magnetic flux generated by the permanent magnet 5 interlinking with the -L element 6 becomes the maximum, and the output voltage of the Hall element 6 becomes the maximum.

Further, when the Hall element 6 faces the side 2b, the magnetic flux generated by the permanent magnet 5 interlinking with the Hall element 6 becomes the minimum, and the output voltage of the Hall element 6 also becomes the minimum. Therefore, the output voltage signal of the Hall element 6 when the motor rotates is as shown in FIG. 2, so by counting the pulses,
Position detection is possible.

FIG. 4 shows a third embodiment of the invention.

In FIG. 4, 7 is an annular non-magnetic body fixed to the movable body 1, and 8 is an annular magnetic body bonded to the non-magnetic body. A permanent magnet 5 having a width equal to or less than the width of the groove 2b is fixed at one location on the magnetic body 8, and a Hall element 6 is attached between the permanent magnet 5 and the vibrating body 20. .

In the vibration wave motor configured as shown in FIG. 4, when the motor is rotating, that is, when the moving body 1 is rotating, when the permanent magnet 5 and the vibrating piece 2a come to a position where they overlap, , a magnetic bus as shown by the arrow in FIG. 5(a) is constructed, and the magnetic flux generated by the permanent magnet 5 interlinks with the Hall element 6 and outputs a corresponding voltage signal. On the contrary, Figure 5 (
When the permanent magnet 5 is in a position where it overlaps fi2b as shown in b), the permanent magnet 5 generates almost no magnetic flux, so the flux linkage with the Hall element 6 is also small, and the output voltage is also small. Also, once per rotation, when the permanent magnet 5 and the Hall element 6 come to a position where they overlap, the magnetic flux generated by the permanent magnet 5 interlinking with the Hall element 6 is in the opposite direction, as shown in Fig. 5(C). , the output voltage of the Hall element 6 has opposite polarity. Therefore, the output voltage of the Hall element 6 in this third embodiment becomes as shown in FIG. 6, and the index signal can also be detected. Moreover, compared to the first and second embodiments, since the Hall element 6 is located closer to the vibrating body 2, the power feeding method is easier.

[Effects of the Invention] Since the present invention is equipped with a position detection device that uses a large number of grooves provided in a vibrating body as an encoder without using an external encoder, it can be carried out in a small space. The cost can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view showing a first embodiment of the present invention;
FIG. 2 is an explanatory diagram of the output voltage waveform in the configuration of FIG. 1 and the configuration of FIG. 3, FIG. 3 is a partially cutaway side view showing the second embodiment of the present invention, and FIG. 4 is a diagram of the present invention. FIG. 5(a) is an explanatory diagram of one action in the configuration of FIG. 4, and FIG. 5(b) is an explanatory diagram of another action in the same manner. , FIG. 5(c) is an explanatory diagram of yet another operation, FIG. 6 is an explanatory diagram of the output voltage waveform in the configuration of FIG. 4, and FIG. 7 is a perspective view for explaining the principle of the vibration wave motor. FIG. 8 is another perspective view. 1... Moving body 2... Vibrating body 2a...
Vibration piece 2b...Groove 3...Light emitting diode/phototransistor 4...Nonmagnetic material 5.
...Permanent magnet 6...Hall element 7...Non-magnetic material 8...Magnetic material Fig. 2 Fig. 4 Fig. 5

Claims (1)

[Claims] (1) A frequency voltage is applied to an electric-mechanical energy conversion element, and a progressive vibration wave is generated in a vibrating body that is joined to the conversion element and has a large number of grooves in the radial direction. A vibration wave motor for driving a body, characterized in that the vibration wave motor is equipped with a position detection device that uses the groove of the vibrating body as an encoder.