JPS59156169A - Controller for vibration wave motor - Google Patents

Abstract

PURPOSE:To efficiently operate a motor by sequentially varying the frequency of a frequency voltage applied to an electrostrictive element and obtaining the frequency that the amplitude of a vibrator becomes maximum. CONSTITUTION:The output of a clock generator CG2 is inputted to drivers DR1, DR2, and traveling vibration waves are respectively generated from electrostrictive elements 3A, 3B by the drivers DR1, DR2. The resistors R0-R4 of the clock generator CG2 are sequentially selected while rotating a vibration wave motor, and the frequency of the applied voltage is gradually reduced. At this time the frequency value of when the vibrating amplitudes of electrostrictive elements 3A, 3B become maximum is stored in a register of a CPU and the generator CG2 then outputs the frequency voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the frequency of progressive vibration waves in order to improve the driving efficiency of a vibration wave motor driven by progressive vibration waves using an electrostrictive element as a driving medium. .

As disclosed in, for example, Japanese Patent Laid-Open No. 52-28192, a vibration wave motor converts the vibration motion generated when a frequency voltage such as an alternating current or pulsating current is applied to an electrostrictive element into rotational interlocking or -dimensional motion. It is something that converts. Compared to conventional electromagnetic motors, electromagnetic motors do not require windings, so they have a simpler and more compact structure, can provide high torque even when rotating at low speeds, and have a small moment of inertia, so they have been attracting attention recently.

However, when conventionally known vibration wave motors convert vibration motion into rotational motion, they use standing vibration waves generated in the vibrator to frictionally drive a rotor or other moving body in contact with the vibrator in one direction. The vibrating body and the moving body come into frictional contact during the forward motion of vibration, and separate during the backward motion. Therefore, the vibrating body and the moving body must have a structure in which they come into contact in a minute range, that is, a structure close to point or line contact, which results in poor friction drive efficiency.

Further, the driving force acts in a fixed direction, and since it is a spider, the moving direction of the moving body is only one direction. In order to move in the opposite direction, it is necessary to mechanically switch the vibration direction using another vibrating body. Therefore, in order to obtain a vibration wave motor capable of forward and reverse rotation, the device becomes complicated, and the simplicity and compactness of the structure, which are the characteristics of the vibration wave motor, are halved.

The structure of a vibration wave motor that eliminates the drawbacks of the vibration wave motor as described above is disclosed in Japanese Patent Application No. 57-2 filed by the present applicant.
It is disclosed in specifications such as No. 06300 and No. 219532.

The outline is as follows.

Figure 1 shows a vibration wave motor disassembled into each element.
are doing.

A vibration absorber 4, a metal annular vibrating body 2 with an electrostrictive element 3 bonded to the side of the absorber 4, and a movable body l are fitted into the central cylindrical portion 5a of the fixed body 5, which serves as a base, in this order. - The absorber 4 and the vibrator 2 are attached so that they do not rotate relative to each other. The movable body 1 is pressed against the vibrating body 2 by its own weight or a biasing means (not shown) to maintain the integrity of the motor.

In the plurality of electrostrictive elements 3, a group of electrostrictive elements 3A to 3A7 are arranged with a pinch of half the wavelength of the vibration wave, and the polarization directions of the electrostrictive elements 3A, 3A, 3, 3A5, and 3A7 are as follows. Electrostrictive elements 3A2, 3A4, and 3A4 are the same and located between them.
The polarization direction of 3A6 is opposite. Therefore, the electrostrictive element 3A, ~
In 3A7, the polarization directions of the adjacent ones are opposite to each other. The other groups of electrostrictive elements 3B, -3B are similarly arranged at a pitch of 1/2, and the polarization directions of adjacent elements are opposite to each other.

Phase n of electrostrictive elements 3A, ~3A, and 3B, ~3B7: Pitch is (no + 174) = O, -1, 2
, 3...) A shifted phase difference arrangement is made.

It should be noted that a plurality of I'E strain elements 3 are not arranged in a row, but as shown in FIG. 2, an annular intermediate element 3 is used and polarized in the pinch described above to form the polarization processing sections 3a, -3a5, and 3b.

~3bs may be used.

A lead wire 11a is connected to the absorber 4 side to each of the electrostrictive elements 3A, -3A, and a lead wire 11b is connected to each of the electrostrictive elements 3B1 to 3B7.
It is connected to the 0° phase shifter 6b (see FIG. 3), and a lead wire 11'c is connected to the gold JA vibrating body 2, which is connected to the AC power source 6a.

The operation of the vibration wave motor configured as described above is as follows.

FIG. 3 shows how the vibration waves of the motor are generated. Electrostrictive elements 3A1 to 3A bonded to the metal vibrating body 2
4 and 3B, to 3B4 are shown adjacent to each other for convenience of explanation, but since they satisfy the above-mentioned input/4 phase shift condition, the electrostrictive element 3A of the motor shown in FIG. ,~3
A4a and 3B.

It is substantially equivalent to the arrangement of ~3B4. In each of the electrostrictive elements 3A, 3A4, 3B, and 3B4, ■ indicates that the electrostrictive elements expand when the alternating current voltage is in the positive cycle, and e indicates that the electrostrictive elements contract in the positive cycle.

The metal vibrating body 2 is connected to electrostrictive elements 3A, ~3A4, and 3B1~B.
4, an AC voltage of V=Vo Si nωt is applied from the AC power supply 6a to the electrostrictive elements 3A and 3A4, and AC voltages a6a to 9 of the AC type are applied to the electrostrictive elements 3B and 3B4.
Through the 0° phase shifter 6b, input/4 phase shifted, V=V
. An AC voltage of 5 inches (ωt±π/2) is applied. The ten or minus in the equation is switched by the phase shifter 6b depending on the direction in which the movable body 1 (omitted in this figure) is moved; when switched to the + side, the phase shifts by +90° and moves in the positive direction, and is switched to the - side. The phase shifts by 90 degrees and moves in the opposite direction. Now switched to the negative side, V=V in the electrostrictive elements 3B, ~'3B4,
A voltage of sin (ωt-π/2) is applied. shall be. Electrostrictive element 3A, ~3A4 injury voltage ■-V. sinω
When the electrostrictive elements 3B and 3B4 vibrate due to the voltage v=Vosin (ω is 1π/2), vibrations occur due to standing waves as shown in Figure (a). Vibrations occur due to standing waves as shown in (b). The above two phase-shifted alternating currents are simultaneously transmitted to each electrostrictive element 3A1.
When applied to ~3A4, 3B, and ~3B4, the vibration wave becomes progressive. (A) is time t = 2nπ/ω, (B) is t = π
/2ω+2nπ/ω, (c) is L−π/ω+2nπ/ω
, (d) is when t=3π/2ω+2nπ/ω,
The wavefront of the vibration wave travels in the X direction.

Such progressive vibration waves are accompanied by longitudinal waves and transverse waves, and as shown in Fig. 4, they arrive at mass point A of the vibrating body 2.
Then, it is performing counterclockwise rotational elliptical motion with a vertical amplitude U and a horizontal amplitude W. Since the movable body 1 is in pressure contact with the surface of the vibrating body 2 and is in contact only with the apex of the vibrating surface, the longitudinal amplitude U of the elliptical interlocking of the mass point A-A... at the apex is
The movable body 1 moves in the direction of arrow N.

The velocity at the apex of the mass point A is V = 2πfu (f is the Oscillatory wave number), and the moving velocity of the moving body 1 depends on this, and since it is moved firmly by friction due to pressurized contact, the lateral amplitude W
It also depends on. That is, mobile object 1. The moving speed of is proportional to the magnitude of the elliptical motion of mass point A.

On the other hand, since the itching drive of the movable body 1 is performed at the apex of the wavefront of the progressive vibration wave of the vibrating body 2,
In order to improve drive efficiency, it is necessary that the wavefront in the Z-axis direction in the figure resonates. Input terminal frequency f(-2
πω) of the vibrating body 2〉・G rate E・Sound intensity ρ・Thickness, h
If the wavelength of the wave created by this is input as (
``There is a relationship of -T main -n 3ρ·πh/in2, and a plate thickness that satisfies this relationship will resonate.

In addition, since the vibrating body 2 is annular, the progressive vibration wave propagates along the ring, and the newly generated wave has a circumference of πD or n times the wavelength (n
is a natural number), that is, it resonates when n = πD.

As the progressive vibration resonates, the amplitude becomes sharper and the drive efficiency of the vibration wave motor is improved.

In order to improve the drive efficiency of such a vibration wave motor, it is necessary to control the frequency of the applied frequency voltage by taking into consideration various conditions such as the thickness of the vibrating body and the ring diameter.

However, even once adjusted, the resonant frequency may shift due to changes in the temperature of the motor itself or the temperature of the oscillation circuit, or due to fatigue of the motor over time, such as wear of the vibrator. be.

In addition, there is also a cost problem in the manufacturing process due to the addition of a frequency adjustment process.

It is an object of the present invention to provide a control device that solves the above-mentioned problems and achieves high driving efficiency of a vibration wave motor. “In order to achieve this objective 1-1, the present invention applies a frequency voltage to an electrostrictive element that is brought into contact with a vibrating body, and a progressive vibration wave is generated in the vibrating body to bring it into contact with the vibrating body. Sequentially vary the frequency of the frequency voltage of the vibration wave motor that drives the moving body, measure the amplitude of the vibrating body at each of the varied frequencies, sequentially compare and calculate the measured values, and calculate the total 71
This is a control device for a vibration wave motor, characterized in that a frequency at which a 111 value is tolerated is stored, and the vibration wave motor is driven with the frequency' voltage of the stored frequency.

The circuit of this 11J control device is shown in FIG.

In the same figure, CI)U is a microcomputer, and DF4 is D
5 is a circuit consisting of 3 type D type flip-flops, BF is a tri-state buffer, G
1.G2 is Nando game 1., II~■9 is inverter,
Di-D2 is a frequency divider, AS is an analog multiplexer,
RO to R15 are resistors, CA P l - CA P 3'
is a capacitor, Tr1 to Tr9 are transistors, Di
is a diode, ADC is an analog-to-digital converter,
ONI is a one-shot circuit, and OPI/OF2 is a buffer amplifier. 3A and 3B are electrostrictive elements, one of which is bonded to the vibrating body 2 of the vibration wave motor, and 11 is an electrostrictive element, which is also attached to the vibrating body 2 in parallel with the electrostrictive elements 3A and 3B. (No. 9)
(see figure).

Inverters l3-I4, capacitor CAP1, and resistors RO-R4 whose values increase in sequence form a clock generator CG2. Analog multiplexer AS is A
One of Xo-X4 is selected by the digital input of O-A2 and electrically connected to the X terminal. Therefore, the resistor RO-R4 is selected by the digital signal, and the clock generator CG2 is selected.
The output CLK of is an oscillation output at a different frequency. The frequency dividers D1 and D2 each divide the frequency by one stage depending on the rising edge of the clock output CLK. Since the frequency divider D2 is connected to the inverter 5, the outputs of the frequency dividers Di and D2 become phase-shifted waveform outputs of ACLK and BCLK shown in FIG. 6, respectively.

Outputs of this waveform are input to driver circuits DRI and DR2, respectively. The driver circuit DRI is composed of a push-pull circuit operated by the output waveform ACLK, and applies a frequency voltage to the electrostrictive element 3A. Driver circuit DR2 outputs waveform B
Similarly, a frequency voltage having a phase shift of 1/4 wavelength is applied to the electrostrictive element 3B using CLK. The applied voltage causes the electrostrictive elements 3A and 3B to vibrate, and the vibrating body 2 also vibrates accordingly.

The vibration motion of the vibrating body 2 is transmitted to the electrostrictive element 11, and an electromotive force is generated in the electrostrictive element 11. The output voltage of the electrostrictive element 11 increases as the vibration amplitude of the vibrating body 2 increases, that is, as the resonance condition improves.

The output voltage of the electrostrictive element 11 is connected via a buffer amplifier OF1 to a peak hold circuit consisting of an ode Di and a capacitor CAP3, and the maximum value of the voltage is stored in a capacitor CAP3. The voltage of capacitor CAP3 is input to analog voltage input VIN of converter ADC via buffer amplifier OF2. flip flop DF
The output of 4 is in transstate, and an output signal is generated at terminals QO-Q3 by inputting to terminal OE.

The microcomputer CPU executes the output command, outputs data to the output bus DBO-DB3, and outputs an L level pulse to the terminal WR.

From this output, Noritsubu flop DF5 becomes DBO~.

Latch the data in DB2. At the same time this output is 'l'
The signal passes through 7/<-II6 and is input to the one-shot circuit oN1, whose output remains at H level for a certain period of time. This H signal is passed through the inverter I9 and the resistor R15 to the transistor Tr9.
is opened, and the peak hold circuit Di@CAP3 operates. In other words, the maximum voltage output from the electrostrictive element 11 during the time period during which the one-shot ONl is at the H level is stored in the capacitor CAP3 as described above.

This voltage is digitally converted by the converter ADC, and when the one-shot circuit ONI changes from H to L level, a trigger signal is applied to the flip-flop DF4 via the inverter I9 and latched.

The tri-state buffer bell converts the signal of the one-shot circuit ONI to inverter I9.
The signal is inputted to the terminal Xi through the terminal and outputted from the terminal Y1.

When the CPU reads data from an external input, the read signal RD output becomes L, and if the address signal AO is L, the output of NAND game) G2 becomes L, and the L signal is sent to OE of /to, faBF. input. When the address signal AO is H, the output of the Nant gate GL becomes L and is applied to the terminal OE of the flip-flop DF4, and the signal of the output QO-q) becomes C.
Loaded into PU.

When the CPU outputs to the outside, the write signal WR becomes L, so the flip-flop DF5 latches the data bus signal of the CPU. The output of flip-flop DF5 is input to analog multiplexer AS, and resistor RO-R4
Choose one.

Further, an integrating circuit consisting of a capacitor CAP2 and a resistor R6 is connected to the Re terminal, and resets the CPU when the power is turned on.

The above circuit operation will be explained with reference to the program flowchart shown in FIG.

When the power is turned on, the microcomputer CPU is reset and the program counter becomes 0, so the program starts from the top of the flowchart.

First, the variable K is initialized to O, and the contents of register RGl are set to the minimum value O (K=O.RGI-〇).

This value is output to the data bus (OUTK). Now =
Since it is 0, the value of flip-flop DF5 is 0,
Resistor RO is selected by analog multiplexer AS. Since the resistance value of the resistor RO is the smallest among the resistors RO-R4, the output wave CLK has the maximum frequency.

At this time, the write signal WR of the CPU applies a trigger to the one-shot cycle y4'-'o Nt via the inverter 6.

Next, input the port at address O (INPUT A
DO). At this time, the output AO of the CPU is L, so the output of /Helaf 7BF is sent to the CPU via the data bus.
is input. Next, it is determined whether the bitl of the data is 0 or 1. That is, it is a determination of the output of the input terminal 9. When bitl is O, that is, when the output of the one-shot ON1 is at H level and the peak hold circuit DleCAP3 is in operation, the program returns to INI.

When the one-shot ONI is at H level, the program repeats this loop, the vibrating body 2 of the vibration wave motor continues to vibrate, and the rotor (moving body) l continues to rotate. When the one-shot ONI becomes L level, the program exits the loop and proceeds to IN2.

IN2 performs port input at address 1 (INPU
TADZ), reads the output of flip-flop DF4.

As mentioned above, since the flip-flop DF4 latches when the output of the inverter I9 becomes H level, the CPU outputs a value corresponding to the maximum output from the electrostrictive element 11 while ONI is at the H level. can be entered.

The value input at IN2 (DATA) and register RG
Compare the lO values. Initially, RG1=0, so DAT
A must be greater than 0 and the program proceeds to MN. Here, DATA is stored in register RG1 (DATA+RG1), and the value " is stored in register RG2 (K-RG2).

The flocram advances to NXT and increments the K value (K+1→K). If DATA is less than or equal to the contents of register RGI, then
The program proceeds to NXT, leaving the contents of RG2 unchanged.

Next, it is determined whether the value is 5 or not. Since it is now l, the program returns to FST again. K to 1
, that is, the resistor R1 is newly selected and the same program is performed.

In this way, while rotating the vibration wave motor, the resistance RO
~R4 is selected one after another, and the frequency of the applied voltage is gradually decreased.

When the variable K becomes 5, the count value when the vibration amplitude of the vibrating body reaches the maximum is stored in the register RG.
2 stores the respective values at that time.

Therefore, the program proceeds to FNS with the branch instruction = 5, and by outputting the value of register RG2', the optimum resistance is selected from among -resistors RO-R and 4, and clock generator CG2 is output. The program ends by controlling the output CLK of.

Then, by this controlled output CLK, the frequency divider D1
・D2 works. Frequency voltages according to the output ACLK of the frequency divider D1 and the output BCLK of the frequency divider D2 are applied to the electrostrictive elements 3A and 3B by the dry circuit DRI@DR2, respectively.

At this time, the frequency of the frequency voltage is controlled to achieve an optimum resonance state with respect to the shape and size of the vibrating body, the vibration amplitude of the vibrating body becomes maximum, and the driving efficiency becomes extremely high.

Since this control is performed when the motor starts driving, it is always controlled in an optimal state even if the usage conditions change each time the motor is driven. Furthermore, there is no need to make fine adjustments to the frequency during manufacturing, and the manufacturing process can be shortened.

Note that the output waveform of the frequency divider in the above embodiment is not limited to the square wave ACLK-BCLK as shown in FIG. 6, but the vibration wave motor operates even if a sine wave is added.

Furthermore, this control device can be applied not only to rotary vibration wave motors but also to linear vibration wave motors.

When using the annular single element 3 shown in FIG.
By detecting the electromotive force from the polarization processing section that is polarized at the same position as the electrostrictive element 11 shown in the figure, that is, between 3a5 and 3b5, the vibration amplitude of the single element 3 is obtained without using the vibration of the vibrating body 2. be able to.

FIG. 8 shows an application example in which a vibration wave motor is used to drive an autofocus lens of a camera, and the autofocus circuit 101 is described in Japanese Patent Application Laid-Open No. 55-1553.
Since this is a publicly known method described in Publication No. 37, its explanation will be omitted.

This circuit is obtained by adding an autofocus circuit 101 and selection games GIO and Gll to the circuit shown in FIG.

When in focus, both outputs of comparators 59 and 60 are L.
level, and when out of focus, the output of either g] comparator becomes H level, so the output is ant game)
The vibration wave motor M rotates forward or reverse when inputted to a selection gate G10 consisting of G12, G13 and an OR gate G14, or a selection game hG11 consisting of AND gates G15, G16 and an OR gate G17. The OR gate 018 is an output ST that becomes H when the motor is driven, and this signal is input to the 5TOP terminal of the microcomputer CPU. When the 5TOP terminal is at the L level, the CPU does not proceed with the program and enters a hold state, so the program proceeds only when the motor is driven for the first time after the power is turned on.

Application examples using the vibration wave motor are not limited to such autofocus; for example, in a camera, the vibration wave motor is applied to aperture control, film drive, and the like.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of the vibration wave motor, Figure 2 is a plan view of an embodiment of the electrostrictive element, Figures 3 and 4 are illustrations of the driving principle of the vibration wave motor, and Figure 5 is the vibration wave motor. FIG. 6 is a diagram explaining the output waveform of the frequency divider, FIG. 7 is a flowchart for implementing the control device of the present invention, and FIG. A control circuit diagram when applied to a mechanism, FIG. 9 is a perspective view of a vibrating body. 1 is a moving body, 2 is a vibrating body, 3A, 3B, and 11 are electrostrictive elements, CG2 is a clock generator, and C'PU is a microcomputer.

Claims (1)

[Claims] (1) A vibration wave motor that applies a frequency voltage to an electrostrictive element that is in contact with a vibrating body, and drives a moving body that is in contact with the vibrating body using progressive dynamic waves generated in the vibrating body. Sequentially varying the frequency of the frequency voltage, measuring the amplitude of the vibrating body at each of the varied frequencies, sequentially comparing and calculating the measured values, and storing the frequency at which the measured value is the maximum,
A control device for a vibration wave motor, characterized in that the vibration wave motor is driven by the frequency voltage having the stored frequency.