JPH03135382A - Oscillatory wave motor - Google Patents

Abstract

PURPOSE:To drive an oscillatory wave motor stably in a wide speed region by changeably forming the two oscillation modes of an in-plane mode and an out-of-plane mode in a diaphragm. CONSTITUTION:An ultrasonic motor is composed of an annular elastic body 1, on a circumferential surface of which an inclined plane 1a is shaped, a piezoelectric element 2, a rotor 3 to which a frictional member 4 is fixed, a support member 7 fastening a bearing 5 and supporting the elastic body 1, etc., and the frictional member 4 is pressure-welded to the inclined face 1a of the elastic body 1. Since the inclined plane 1a is formed to the elastic body 1, progressive waves at both modes of an out-of-plane mode and an in-plane mode are shaped in the inclined plane 1a, and the rotor 3 can be driven in either mode. Accordingly, one mode is used for revolution at high speed and the other mode for revolution at low speed, thus allowing stable drive in a wide speed region.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibration wave motor, and more specifically, it is capable of switching speed ranges, and decelerates when approaching a search area, such as when searching for microfilm. The present invention relates to a vibration wave motor that can be used for X-Y stages and θ stages for both coarse and fine movements, and for paper feed devices of printers and copying machines that require high torque only when feeding paper.

[Prior art] Conventionally, vibration wave motors have generally used an out-of-plane vibration mode, and those using an in-plane vibration mode have been described in Japanese Patent Laid-Open No. 6
No. 0-210173, No. 60-210175, etc., vibrate a vibrating body using in-plane vibration mode, torsional vibration mode, or out-of-plane imaging and rapid vibration of torsional vibration, and frictionally drive a moving body in contact with it. , it is designed to be driven in one mode.

[Problems to be Solved by the Invention] By the way, a vibration wave motor has excellent drive characteristics in a low speed range, but in order to drive at a lower speed, the vibration amplitude of the elastic body must be reduced, so the rotation is slow. It becomes stable. Therefore, low-speed driving is performed by switching to burst driving or the like, but this has the disadvantage of increasing speed unevenness.

Furthermore, since only one characteristic can be selected, there is a drawback that the application is narrow.

An object of the present invention is to provide a vibration wave motor that can be driven stably over a wide speed range.

[Means and operations for solving the problem] The gist of the present invention is to switch between an out-of-plane vibration mode and an in-plane vibration mode formed on a diaphragm, and to change the frequencies of both modes. can be designed arbitrarily, but if the frequency difference between the two motes is about a few percent, and the distance between the friction surface of one mode and the neutral axis is 15 times that of the other, then the If the vibration amplitude is the same, if a progressive vibration wave is generated, the vibration amplitude in the feeding direction in which the friction material in contact with the diaphragm is moved is approximately proportional to the distance between the friction surface and the neutral axis. The vibration amplitude in the feed direction of one mode is approximately 1.
One mode is used for high-speed rotation, and the other mode is used for low-speed rotation, allowing stable driving over a wide speed range.

Embodiments Embodiment 1 FIG. 1 is a sectional view showing Embodiment 1 of a vibration wave motor according to the present invention. 1 is an annular elastic body with an inclined surface 1a on the inner circumference; 2 is a piezoelectric element made of an electro-mechanical energy conversion element such as a piezoelectric body fixed to the bottom surface of the elastic body 1; 3 is an inner circumference. 4 is a friction member fixed to the outer peripheral end of the rotor 3; 5 is a bearing supporting the central axis 3a of the rotor 3; 6 is a screw threaded portion 3b provided on the central axis 3a of the rotor 3; a nut for adjusting the pressing force between the rotor 3 and the elastic body 1 via the friction member 4;
7 is a support member that fixes the bearing 5 and supports the elastic body 1; 8 is a felt that is inserted between the elastic body 1 and the support member 7 to absorb vibration; The member 4 is pressed into contact with the member 4. That is, the elastic body 1 has an inclined surface 1a.
By providing this, traveling waves in both the out-of-plane mode and the in-plane mode can be formed on the inclined surface 1a, and the rotor 3 can be driven in either mode.

The neutral axis in the in-plane mode is in the rotational axis direction of the rotor 3, and the neutral axis in the out-of-plane mode is in the radial direction of the elastic body 1, and L1 in FIG. 1 is the neutral axis in the in-plane mode, L2
is the neutral axis of the out-of-plane moat, and when the width (W) of the elastic body 1 is made larger than the thickness (H), the resonance frequency f1 in the in-plane mode and the resonance frequency f2 in the out-of-plane mode will be different.

The resonance frequencies f1 and T2 are approximately determined by the ratio of the width (W) and thickness (H) of the elastic body 1, and are expressed as f1~-T2H, and the speed ratio when the vibration amplitudes of both modes are made equal is If the speed in the inside mode is 19 and the speed in the outside mode is V2, it is expressed as follows. Here, for example, if W=1.5H,
v,/v,=2.25. Also, when driving a vibration wave motor, the optimal vibration and amplitude of the elastic body are as follows:
It is determined by the surface roughness of the contact area between the elastic body and the friction material, and good wow and flutter performance is determined by the surface roughness of the contact area between the elastic body and the friction material.
] (peak to peak), and for safety reasons such as destruction of the piezoelectric element, the vibration amplitude is 2.0.
~2.5 [tt m] (peak to pea
k) The following are desirable. Therefore, the speed range when controlling the speed by changing the vibration amplitude is about 2.5 times the speed range.

In this embodiment, by setting W≧1.5H, the speed ranges of both vibration motes can cover not only two different speed ranges but also a wide continuous speed range.

Next, changes in speed performance depending on the angle of the slope provided on the contact surface between the elastic body 1 and the I2 friction material 4 will be explained. FIG. 13 is a sectional view of the elastic body 1.

FIG. 3(a) shows the vibration component during in-plane vibration, and FIG. 2(b) shows the vibration component during out-of-plane vibration. In the figure, T, , T, are vibration components that contribute to the rotation of the motor, and T2 and T2 are vibration components in the sliding direction that do not contribute to the rotation.

As is clear from the figure, T = T = T.

Inside and outside, T+ = ToXsin θ, T2 = Toxco
within s θ
Inner TI = ToXCOS
θ - T2 = To We will discuss the effects of T2 and T2 on a certain first order.

Everything inside and outside will be a loss. Therefore, in this example, in order to equalize the loss due to sliding vibration in both modes and increase the overall efficiency, the angle of the slope provided on the elastic body l is set to 45.
°. Further, depending on the balance between the usage times of both modes, the angle θ of the inclined portion provided on the elastic body 1 may be selected so as to reduce the sliding vibration loss in the vibration mode with the longer usage time.

FIG. 2 shows the electrode pattern of the piezoelectric element 2 shown in FIG. 1, and the + and - signs indicate the direction of polarization.

In FIG. 2, 2-a and 2-b are driving electrode groups (hereinafter referred to as By applying AC voltages whose temporal phases are shifted by 90° to the A phase 2-a and the B phase 2-1], the positional phase changes to λ/ on the elastic body 1. Two standing waves shifted by 2 are generated, and a progressive vibration wave is generated by combining these two standing waves. Then, the frequency of the AC voltage applied to the A phase 2-a and the B phase 2-b is set near the resonance frequency of the in-plane mode and near the resonance frequency of the out-of-plane mode, and by switching between these two modes, the rotor 3 is rotated. It allows you to switch speeds. Reference numeral 2-c denotes an electrode for detecting the vibration of the vibrating body, which is divided into two in the radial direction so that both in-plane mode and out-of-plane mode vibrations can be detected. In this example, it is divided into six parts, and the middle electrode of the three on the inner circumference or the middle TL pole of the three on the outer circumference is used, and the others are used by short-circuiting between them and the vibrating body. . 2-d is an open electrode which is normally short-circuited with the vibrating body.

Example 2 FIG. 3 is a sectional view showing the second embodiment.

In this example, a vibration wave motor is configured in a cylindrical shape, and has 9
10 is an elastic body having an inclined surface 9a on the outer periphery; 10 is a support plate;
11 is a bearing, 12 is a leaf spring, 13 is a friction member, 1
4 is felt, 15 is a friction material fixing ring, 16 is a spacer, 17 is a rotor, and 18 is a friction material fixing screw.

FIG. 4 is a plan view of the elastic body 9, in which a plurality of protrusions 9b are formed on the inner periphery, and rotation is prevented between the elastic body 9 and the support plate 10 using a bottle (not shown) or the like.

Embodiment 3 FIG. 5 shows an electrode pattern of a piezoelectric element for increasing the vibration efficiency of the in-plane solder compared to the pattern in FIG. 2. Space=8i2d is divided in the radial direction, and the polarization direction is changed between the inner and outer circumferences. 1st A
Phase 19-al, second A phase 19-a2. 1st B phase 19-b
The second B phase 19-b2 connects adjacent electrodes in the circumferential direction, and the polarity of the electrode pattern is set to λ/
The dividing point between the inner and outer circumferences is the neutral axis of the in-plane mode. The first open electrode 19-di and the second open electrode 19-d2 are short-circuited to the elastic body. Further, either the center electrode of the first vibration detection electrode group 19-cl or the center electrode of the second vibration detection electrode group 19-c2 is used as the vibration detection electrode, and the other electrodes are short-circuited to the elastic body 1. has been done.

The applied voltage during driving is the 1st A phase 19- in the in-plane mode.
al and the second A phase 19-a2, and the first B phase 19-b1 and the second B phase 19-b2 are the same phase AC voltages, and the first
The temporal phases of the AC voltages applied to the A phase 19-al and the first B phase 19-bl are shifted by 90 degrees, and in the out-of-plane mode, the first
A phase 19-al, second A phase 19-a2, and first B phase 19
-b 1 and the second B-phase 19-b2 are AC voltages with opposite phases, respectively, and the temporal phases of the AC voltages applied to the first A-phase 19-at and the first B-phase 19-bl are shifted by 90 degrees.

FIG. 6 shows the electrode pattern shown in FIG. 5 with a flexible electrode for power supply attached. 20 is flexible N, h, terminal a1 is the first A phase 19-al, terminal a2 is the second A phase
Phase 19-a2, terminal C1 is the first vibration detection electrode group +9-
cl, the terminal c2 is the middle electrode of the second vibration detection electrode group 19-c2, and the terminal b1 is the first B phase 19-
b1. The terminals b2 are respectively connected to the second B phase 19-b2.

FIG. 7 is a block diagram of a drive circuit when the electrode pattern of FIG. 5 is used.

Reference numeral 21 denotes a mode switching command device for commanding mode switching, which outputs a mode command signal in response to a command from a speed command device (not shown) or the like. 22 are terminals al, a2 . of the flexible electrode 20 . A reference signal generation circuit for generating an AC voltage and a reference signal to be applied to bl and b2,
The variable range of the frequency of the AC signal is switched according to the mode command signal of the mode switching command device 21, and the amplitude of the signal from the vibration detection electrode cl (the middle electrode of 19-cl), the temporal phase difference with the reference signal, etc. The frequency is controlled so that is a predetermined value. 23 outputs a signal 90 which advances or delays the reference signal by 90 degrees in time according to a rotation direction command signal from a rotation direction command means (not shown).
A phase shifter 24 is a forward/reverse switch for switching whether or not the reference signal is inverted by the mode command signal; 25 is a 90° phase shifter (the output signal of the prephasor 23 is inverted by the mode command signal); The forward/reverse switch 26.27, 28.29 is a power amplifier whose output side is connected to the terminals at, a2.bl, and b2. In the case of in-plane mode and out-of-plane mode, Fig. 8(a) and (b)
) The voltage is applied at the timing shown in . In addition, the 8th
FIG. 8(a) shows the in-plane mode, and FIG. 8(b) shows the out-of-plane mode.

Embodiment 4 FIGS. 9 to 12 each show an example of a groove structure formed in an elastic body, in which (a) is a cross-sectional view, the grooves are indicated by dotted lines, and (b) is a plan view.

In the embodiment shown in FIG. 9, grooves 30 are provided at the upper and inner peripheral portions of the elastic body 1 with a constant width.

In the embodiment shown in FIG. 10, grooves 30 are provided on both sides in the radial direction except for the contact portion 1a with the friction material, in order to improve wow and flutter.

The embodiment shown in FIG. 11 is an example in which the width d of the projection 31 on which the inclined surface 1a is formed is constant, and the embodiment shown in FIG. In the example of dimensions, the widths (W) of the groove portion 31 and the protrusion portion 32 are radial and have equal central angles.

Incidentally, in each of the above-mentioned embodiments, an annular shape was used, but the same applies to other shapes such as an oval shape.

[Effects of the Invention] As explained above, according to the present invention, one motor can be electrically switched by forming a diaphragm so as to be able to switch between two vibration modes: an in-plane mode and an out-of-plane mode. Depending on the method, it can be used as two motors with completely different characteristics, so the speed can be switched between medium speed (low speed) and ultra low speed, and various combinations of motors can be realized, which requires high precision drive over a wide speed range. It has an effect that can be used for various purposes.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a first embodiment of the vibration wave motor according to the present invention, Fig. 2 is a plan view showing its electrode pattern, Fig. 3 is a sectional view showing the second embodiment, and Fig. 4 is an elastic body thereof. FIG. 5 is a plan view showing the electrode pattern of Example 3, and FIG. 6 is a plan view showing the electrode pattern of Example 3.
The figure is a plan view of flexible electrodes connected to the NJfi pattern in Figure 5, Figure 7 is a block diagram showing the drive circuit of Example 3, and Figures 8 (a) and (b) are in-plane and out-of-plane modes. Waveform diagrams in FIGS. 9(a), (b), FIGS. 10(a), (b), FIGS. 11(a), (b), and FIG. 12(a). (b) is a sectional view and a plan view of grooves formed in the elastic body, respectively. FIGS. 13(a) and 13(b) are cross-sectional views of the elastic body 1 showing vibration components of in-plane and out-of-plane vibrations. 1... Elastic body 2... Piezoelectric element 3... Rotor 4... Friction material 5... Hair ring
6... Nut 7... Support member 8...
Felt 1st figure 2nd figure = a '-1 3rd figure 2nd figure

Claims (1)

[Scope of Claims] 1. Two groups of drive electro-mechanical energy conversion element sections are arranged on an annular or oblong diaphragm made of an elastic material at an equal pitch of λ/2 within the group, and with voltage The polarities of expansion and contraction during application are alternately reversed, and the groups are arranged and fixed so that there is a shift of an odd multiple of λ/4, and the driving electricity is
By applying alternating current voltages having a constant temporal phase difference to the two groups of mechanical energy converting element sections, two groups of different wavelengths λ having a temporal phase difference generated by the respective groups are applied to the diaphragm. A vibration wave motor that generates a progressive vibration wave with a wavelength λ as a synthesis of standing waves to relatively move a member that is in pressure contact with the vibration plate and the vibration plate, the driving of the two groups. A vibration wave motor characterized in that a driving means for applying an alternating current voltage to the electro-mechanical energy conversion element section switches the vibration formed on the vibration plate into a plurality of modes. 2. The vibration according to claim 1, wherein the driving means generates vibrations in an in-plane mode and an out-of-plane mode, and switches the speed of the diaphragm and a member that moves relative to the diaphragm. wave motor. 3. Claim 1 or 2, characterized in that the ratio between the width and thickness of the diaphragm is 1.5 times or more on the longer side than on the shorter side.
The vibration wave motor described in . 4. The vibration wave motor according to claim 1, 2 or 3, wherein the frictional contact surface between the diaphragm and the member that moves relative to the diaphragm is an inclined surface. 5. The vibration wave motor according to claim 4, wherein the frictional contact surface has an inclination angle of 45 degrees. 6. The vibration wave motor according to claim 4, wherein the rated rotational speed of the friction contact surface is changed between an out-of-plane mode and an out-of-plane mode by changing the inclination angle of the friction contact surface. 7. Provide radial grooves at equal intervals in the circumferential direction on either the inner circumference or the outer circumference of the diaphragm, and provide radial grooves at equal intervals in the circumferential direction on the opposite side of the surface to which the electro-mechanical energy conversion element is fixed. Claims 1 and 2 characterized in that radial grooves are provided.
, 3, 4, 5 or 6. 8. The vibration wave motor according to claim 1, 2, 3, 4, 5, or 6, characterized in that no groove is formed in the contact portion of the inclined surface of the diaphragm with the relative moving member. 9. Claim 2, wherein the relative movement speed is switched between an in-plane vibration mode and an out-of-plane vibration mode in response to a speed command or a detection signal from a speed detection section.
, 3, 4, 5 or 6. 10. The vibration wave motor according to claim 7, wherein the width of the grooves formed in the diaphragm or the interval between the grooves is constant.