JPS63209481A - Controlling circuit of oscillatory wave motor - Google Patents

Abstract

PURPOSE:To start a motor in a short time, by setting the frequency at which the motor actually began to pivot in the last drive as the starting frequency in the next motor drive, and by transferring it to the frequency for desired speed. CONSTITUTION:A controlling circuit of an oscillatory wave motor is constituted by the use of a microcomputer CPU, of which from an output port PA the information deciding the driving frequency is outputted, while from an output port B1 the motor drive signal and from another output port PB2 the direction signal to decide normal or reverse rotation are respectively sent out and from other output ports PC0-PC3 the resonance frequency information is outputted. A phase locked loop is composed of a DA conversion circuit DA, a comparator CP1, a low pass filter LPF1, voltage control oscillator VCO1 and a division circuit FR1, with which the frequency is detected when the rotation of motor begins, and this frequency information is set out as the frequency initial value in the next starting of rotation. After starting, it is transferred to the frequency for desired speed and the frequency in the abovementioned starting is held in an RAM.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention generates progressive vibration waves on the surface of a vibrating body by applying a frequency voltage to an electro-mechanical energy conversion element such as an electrostrictive element or a piezoelectric element. The present invention relates to a control circuit for a vibration wave motor that drives a moving object using the vibration waves.

(Prior Art) A method is known in which the frequency of the frequency voltage is varied in adjusting the speed of this type of motor.

When setting the motor to the desired speed using this method,
It is sufficient to select a frequency corresponding to the desired speed and apply it to the electro-mechanical energy conversion element, but with this method, the motor starts rotating suddenly, and it is not possible to rotate the motor smoothly. do not have.

In order to solve the above problem, 'when starting the motor, the driving frequency may be gradually lowered from a high frequency to a frequency corresponding to the desired speed in 8 lines.

In this case, the high frequency at startup is set to the frequency at which the motor actually starts rotating, and if the frequency is gradually lowered from this set frequency, the motor can be smoothly driven to the desired speed in a short time. However, the characteristics of the motor mentioned above are not constant and are affected by environmental changes such as temperature, so if the frequency at the start of startup is fixed, it will not be able to cope with changes in temperature, and the characteristics of the above motor will not be constant until the sudden rotation or the start of startup. This causes inconveniences such as a longer time.

〔the purpose〕

The present invention has been made in view of the above-mentioned problems, and when starting the motor, the frequency applied to the motor is gradually lowered from a predetermined high frequency to a frequency corresponding to the desired speed, and the frequency applied to the motor is By setting the frequency to the frequency at which the motor actually started rotating the last time the motor was started, it is possible to start the motor smoothly and in a short time.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of a control circuit for a vibration wave motor according to the present invention.

In the figure, CPU indicates a microcomputer.

In the computer CPυ, PAO~P A t
is an output port, and information for determining the drive frequency is output from the port. Further, a motor drive stop signal is sent from the output port PB+, and a direction signal that determines forward/reverse rotation of the motor is sent from the output port PB2. PC
O~PC3 are output ports that output resonance frequency information, P
Do is an input port for inputting a lock signal, and PEG is a port for inputting pulses from the encoder ENC.

DA is the output port P A o ~ PA7 of the above CPU,
This is a digital-to-analog (DA) conversion circuit that connects the board and performs DA conversion of information output from the board. op...
OP, TR, and TR2 are operational amplifiers and transistors, respectively, and OP, and Tr form a current according to the output of the DA conversion circuit, and the transistors Trs and T
The current is formed in a current mirror circuit consisting of r4. Also, the above OP2. Tr2 is an offset circuit in which an offset current is generated, and as a result, the transistor Tr2 forming a current mirror circuit
4, a current is formed by adding the offset current to the current corresponding to the output of the DA converter circuit.

C1 is a capacitor charged by the output current of the transistor Tr4, CP is a comparator, and Trs is a transistor. When the capacitor CI is charged to a predetermined voltage Vc, the comparator CPI sets the output to a high level (hereinafter referred to as 1). ) and transistor Tr5
Turn on. Therefore, the comparator CP1 outputs a pulse having a frequency corresponding to the current value of the transistor Tr4. DFFl is a D flip-flop whose clock terminal is connected to the output terminal of the comparator CPs,
The flip-flop operates in synchronization with the pulse from the comparator CP1, and converts the output pulse of the comparator CPI into a pulse with a duty of 50%.

Pct is a phase comparator, and when the phases of the input pulses to the inputs R and S match, the output is set as an oven, and the degree of coincidence of the input pulse phases is, for example, different from the pulse to the R input terminal to the S input terminal If the pulse at the S input terminal is delayed, the output will be set to a high level (hereinafter referred to as 1) by the amount of delay, and conversely, if the pulse at the S input terminal advances with respect to the pulse to the R input terminal, the output will be set to a low level (hereinafter referred to as 1) by that amount. 0), LPF is a low pulse filter, for example, P C+
When the output becomes 1, the output level is increased, and when it becomes 0, the output level is decreased, and when the oven is used, the output level is maintained. The VCOI is a voltage controlled oscillator, and its output frequency is configured such that the larger the output of the LPF, the higher the frequency. FR is a frequency dividing circuit that divides the output of the VCO by 32. The above configuration (PC+
, LPF+, VCO+.

FBI) configures a phase-locked loop 1, and controls the S and R inputs of comparator Pc1 to be the same pulse, and as a result, the output of VCO□ is 32f1, which is 32 times the pulse frequency f of DFF. Outputs a pulse of

SR is an 8-bit shift register whose D input is connected to the Q output of the DFF1, and its clock input is connected to the output of the VCO.

With this configuration, the shift register SR outputs a pulse whose phase is shifted by 90 degrees with respect to the pulse to the D input.

ex is an S-OR gate, which inputs the Q output of the register SR and the direction signal DIR from the output port PBz of the CPU, and when the signal from the output port PB2 is 0, the gate outputs the Q output of the register SR. Q of ,
The output is output as is, and when it is 1, register SK
The Q output of , is inverted and output. With this, gate e
The output pulse of Xl is set to be a pulse offset by ±90@ with respect to the flip-flop OFF, and the rotation direction of the motor is switched. AN, , AN2 are AND gates, and these gates respectively input the output of the DFFI and the output of the gate ex to the amplifier AP.

Tell AP2. BI is a vibrating body in which an electrostrictive element is arranged. The vibrating body has, for example, a ring shape, and an electrostrictive element is arranged on the surface of the vibrating body. Further, a moving body having the same shape as the vibrating body is in frictional contact with the surface of the vibrating body, and is driven by progressive vibration waves generated in the vibrating body.

FIG. 2 is an explanatory diagram showing the arrangement of electrostrictive elements arranged on the surface of the vibrating body BI. AI and B in Figure 2,
are first and second electrostrictive element groups arranged on the vibrating body Bl in the illustrated phase and polarization relationships, respectively. Further, S1 is an electrostrictive element for a sensor arranged at a phase shifted by 45 degrees with respect to the first electrostrictive element group B1. Each of these electrostrictive elements may be attached to the vibrating body individually, or may be formed integrally by polarization treatment.

Returning to FIG. 1, A, B, and S are respectively 1. A drive electrode and a sensor electrode are shown for the second electrostrictive element group and the sensor electrostrictive element St, and the amplifier AP is connected to the electrode A.
A frequency voltage is applied to the electrode B via the AP, and a frequency voltage via the AP is applied to the electrode B.
A progressive vibration wave is formed on the surface of the cloth. Further, when the vibration wave is formed in the vibrating body, the sensor electrostrictive element S outputs an output (frequency voltage) according to the state of the vibration wave, and this is detected by the sensor electrode S1.

In addition, in a resonant state, the vibration wave motor has a characteristic that the phase relationship between the drive voltage to the A electrode and the output voltage from the sensor electrode is a specific relationship, and a frequency signal is applied at the electrode A. The phase relationship between the first electrostrictive element group AI and the sensor electrostrictive element S is determined, and in the case of this embodiment, resonance occurs when the signal waveforms of the electrodes A and S are out of phase by 135 degrees in the normal rotation state. In addition, in the case of reversal, a resonance state is indicated when the angle shifts by 45 degrees, and the further the shift from resonance, the more the above-mentioned phase difference relationship shifts. CP2°CP represents a comparator that shapes the output waveforms of the electrodes A and S into a pulse shape, respectively.

FR is a 4-bit shift register whose D input is the output of the comparator CP2 and whose clock input is connected to the output of the VCOI.
Shifts the frequency signal by 45 degrees. FR3 is an 8-bit shift register whose D input is connected to the Q output of the shift register FR2, and whose clock input is connected to the output of the VCO.The output of the shift register FR2 is further shifted by 90 degrees, and the entire comparator is Shift the output of the controller CP2 by 135°. SEL is shift register F
This is a data selector that selects the output of R or FR. The selector selects input B when the signal DIR at the output port PB2 indicates normal rotation, and selects input A when it indicates reverse rotation.

PC2 is a phase comparator that detects the phase relationship of the input pulses to inputs S and R as shown in Figure 3, and the larger the phase difference, the smaller the output duty of 1 from the bottom of the output Σ is output. .

11 is an inverter, C0UI is a counter, AN3 is an AND gate, and the above counter is a reset input RES.
It is reset when the signal to ET is 0. Further, the AND gate AN3 is connected to the inverter 1. When the output of COU1 is 1, the pulse from the VCOI is transmitted to the counter COU1.

In the above configuration, the counter COU + counts pulses from VCOI while the output of the comparator PC2 is 0, and as the motor approaches a resonance state, the count value of the counter C0UI decreases. MCI is input (AO
~A3) and (B.

~BS) and outputs 1 when A<B. The output of the comparator MCI is connected to the D input of the D-type flip-flop DFF2. The clock input of the flip-flop DFFz is connected to the output PD of the comparator PC2, and detects the state of the D input in synchronization with the rise of the pulse to the clock input.

LPF is a low-pass filter, and C20 is a comparator, which transmits a 1 signal to the input port PDφ of the CPU in response to the Q output 1 of the flip-flop DFF2.

The ENC is a code plate, such as a pulse plate, which rotates in conjunction with the moving body of the motor, and forms pulses with a frequency corresponding to the rotational speed of the motor.

RAM is a random access memory that communicates data with the CPU. The RAM is a backup power supply BT,
Power is constantly supplied from the main switch SW, and power is also supplied from the power supply BT2 via the main switch SW. Moreover, the amplifier AP is connected to the power supply BT2.

Power is supplied to each circuit section except AP2.

SW2 is a switch that is turned on in conjunction with the switch SW1, and the high voltage power supply BT is connected via the switch SW2.
The output of S is the amplifier AP.

A P x is supplied. SW is a reset switch that resets the contents of the memory RAM.

Figure 4 shows the R built in the computer CPU in Figure 1.
FIG. 2 is a program diagram showing a program flow programmed in the OM, and the computer CPU executes control operations according to the program flow.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

When the main switch SW is now turned on, the output of the power supply BT2 is applied to each circuit. Now computer C
PU starts operating.

When the computer CPU starts operating, step 1 is executed first. The operation of each step will be explained below.

Step 1: Output O from output port PBo and 0 from PB. A predetermined set value $3 is output from output ports PC0 to PC.

Step 2: Enter valid bit data in RAM manually.

Step 3: When the above data is O, variable FMAX=$
FF, and when it is 1, the previous highest frequency stored in the RAM is read out, and FMAX=previous highest frequency.

When the motor is driven for the first time, the valid bit data is O, and the variable FMAX is set to $FF.

Step 4: From the output ports PAO to PA, the above variable F
Output MAX. The variable FMAX information from the boat is converted into an analog voltage by the DA converter DA, and the amplifier o
A current value corresponding to the variable FMAX flows through the transistor Tr< by the action of p, , OP2 and the transistor TrINTRr4.

Step 4': Store the variable FMAX in the internal memory F.

Step 5: Output 1 from output port P B o. 0 from the boat PBo acts as a so-called busy signal, and the busy state is canceled and the computer C
This indicates that communication with the computer CPU is permitted for a circuit (not shown) connected to the PU.

Step 6: Detect data input from a circuit (not shown) to the human power boat SDI of the computer, determine whether or not a drive command signal is input manually as data from the circuit (not shown), and determine whether the drive command signal is input. Steps 5 and 6 are repeated until the drive command signal is input, and the process proceeds to step 7. The drive command signal is generated when a manually operated starting switch provided in a circuit (not shown) is turned on, and is input to the human-powered boat SDI, and is generated when the starting switch is operated. Step 7
Transition to.

When step 5 is executed, communication with the circuit (not shown) is allowed as described above, and during this time, data such as motor rotation speed information 1 rotation amount information 2 rotation direction information set in the circuit (not shown) is transmitted. is the computer input boat SDI
is input.

Step 7: Set the output boat PB0 to 0, prohibit communication between the unillustrated circuit and the computer CPU, and store the rotation amount information set above as the specified number of pulses in the memory C0U.
The set rotational speed information is stored in the VEL as a designated speed. Further, the output boat PB2, PB61, or O is output based on the set rotational direction information.

Also, information 1 or O from the input boat PEO is stored in the memory P.
Enter LEVEL. The input boat PEO is connected to an encoder ENC, which is composed of a code plate (pulse plate), etc., and forms a pulse, that is, a repetition of a 1.0 signal by rotation of the motor. Therefore, the output of the encoder ENC before the motor starts rotating is O or 1 depending on the initial position of the code plate, and this initial state of the code plate is stored in the memory PLEVEL.

Step 8: Output 1 from the output port FBI. This opens AND gates ANI and AN2',
The output of the flip-flop DFFI and the output of the exclusive OR gate 8Xl are transmitted to the amplifiers API and AP2.

As mentioned above, the transistor Tr4 has the variable FMAX=
A current corresponding to $FF is flowing, and the flip-flop OFF outputs a pulse with a frequency corresponding to the current value as described above, and the exclusive OR gate exI outputs the output of the flip-flop DFF as described above. Since a pulse with a phase difference of 90 degrees with respect to the pulse is output, a frequency voltage of a frequency $FF with a phase difference of 90 degrees is applied to electrodes A and B of the motor, and the motor starts rotating.

Step 9: Reset the internal timer and then release the reset. The timer now starts counting.

Step 10: It is detected whether or not the timer has counted a predetermined period of time. If the timer has not elapsed, the process proceeds to step 11; if the timer has elapsed, the process proceeds to step 13.

Step 11: It is detected whether the input signal from the input boat PEo and the signal in the memory PLEVEL are the same. If they are the same, the process goes to step 10 again, and if they are not the same, the process goes to step 12.

The memory PLEVEL stores the signal of the encoder ENC before starting the motor, and when the motor rotates from that state, the output signal of the encoder ENC changes, so it becomes inconsistent with the signal stored in the memory PLEVEL. Therefore, in this step, a change in the signal of the encoder ENC is detected to detect whether or not the motor has actually started rotating, and when the motor has started rotating, the process moves to step 12.

Now if the motor does not start rotating within the time counted by the timer, steps 10.11 above are repeated;
When the timer is up, the process moves to step 13.

Step 13: Add -1 to the variable FMAX and use FMA
Let X-1 be a new variable FMAX.

Step 14: R with the new variable as the previous highest frequency
Manpower for AM.

Step 15: Set valid pit data in RAM to 1.

Step 16: Output the new FMAX obtained in Step 13 from the output ports P A o to P A 7, update the driving frequency to electrodes A and B as described above, and input the FMAX to the memory F. Then, proceed to step 9 again. By performing the processing in steps 13 to 16, FMAX becomes -1, and the set frequency decreases (lowers). Therefore, even though the motor has started to be driven in step 8, if the motor does not actually start rotating, the set frequency is decreased (lowered) by a fixed amount at predetermined time intervals. As a result, the driving frequency for the motor gradually decreases, and the driving frequency for the motor is scanned.

Further, when the motor rotates while the drive frequency is being scanned as described above, the step shifts to step 12 as described above. Therefore, the frequency at which the motor actually starts rotating is stored in the RAM.

As described above, the frequency of the frequency voltage applied to the electrodes A and B is updated (decreased), and when the motor starts rotating, step 12 is executed.

Step 12: Measure the pulse interval time from the encoder input to the input boat REO to determine the rotational speed of the motor. This pulse interval 1fllJf measures the interval time between two pulses that are continuously input from the encoder ENC.

Step 17: Compare the detected rotation speed obtained in step 12 with the specified rotation speed stored in the memory VEL, and if the detected rotation speed is less than the specified rotation speed, proceed to step 19,
Detected rotation speed> When the specified rotation speed is reached, the process moves to step 18, and when the detected rotation speed - the specified rotation speed, the process moves to step 20.

The lower the driving frequency, the faster the motor rotates, and as mentioned above, the driving frequency of the motor is gradually lowered from $FF to move the motor into a rotating state, so normally when the motor starts rotating, the detected rotational speed is There is a relationship of <VEL, and the process moves to step 19.

Step 19: Subtract -1 from the contents of memory F, ie, FMAX at the time the motor starts rotating, and input FMAX-1 to memory F.

Step 20: Input the contents of the memory F above into the board P.
Since 0 is input to the 0 normal input port PDO to which the value of Do is added, normally the contents of the memory F do not change in this operation.

Step 21: Output port PAO~PA? The contents of the memory F are output from. As a result, the driving frequency for the motor is reduced by a certain value from the frequency FMAX at the start of motor rotation, and the motor rotates at a higher speed.

Step 22 -1 is applied to the number of pulses representing the rotational speed of the motor set in memory C0UNT.

That is, the pulse interval time measurement process in step 12 is as follows:
This is done every time one pulse is input from the encoder ENC, so by executing the above step, the motor is driven by one pulse, and the -1 above is executed.
, calculate the remaining rotation amount and store it in the memory C0UNT.
Enter 1.

Step 23: Detect whether memory C0UNT=O or not. If C0UNT=O, go to step 12 again and C0
When UNT=O, the process moves to step 24.

That is, when the remaining motor rotation amount is not zero due to the rotation of the motor, the process moves to step 12 again and the above operation is repeated.

Each time the above steps 12, 17, and 19 to 23 are repeated, the motor drive frequency gradually decreases.
The rotational speed of the motor will gradually increase.

If the rotational speed of the motor reaches the designated speed by repeating the above steps, this is detected in step 17, and the process proceeds to step 20 without going through step 19.

Therefore, when the number of rotations of the motor reaches the specified number of rotations, the -1 operation on the contents of the memory F is stopped, the motor is driven at the driving frequency at that time, and the rotational speed also becomes the specified speed.

A case will be explained in which the motor speed exceeds the specified drive for some reason while the motor is rotating at the specified speed.

In this case, since the rotational speed>VEL is detected in step 17, the process moves to step 18.

Step 18: Compare the contents of memory F and FMAX stored in RAM, and if F≦FMAX, step 2
5, or if F>FMAX, proceed to step 26.

Now, in the above step, it is assumed that the contents of the memory F are smaller than the contents when the motor is driven, that is, FMAX stored in the RAM. In this case, the process moves to step 25.

Step 25: Add +1 to the contents of memory F,
Input F+1 into memory F, move to step 20,
Thereafter, rotation speed>VEL.

As long as F≦FMAX, repeat steps 12→17→18→25 and steps 20→21→22-23.

Therefore, when the rotational speed becomes higher than the designated speed, the driving frequency gradually increases and the rotational speed decreases.

In each step explained above, the rotation speed of the motor is normally servo-controlled to the specified speed, but even if the contents of memory F are larger than FMAX for some reason during the deceleration operation, the speed cannot be decelerated to the specified speed. The case where there is no such information will be explained.

When such a state ()")FMAX) is detected in step 18, the process moves to step 26.

Step 26: Set the contents of memory F as variable FMAX. As a result, a higher frequency FMAX is formed with respect to the FMAX stored in the RAM when the motor starts rotating.

Step 27: Set FMAX formed in step 26 above in the RAM as the new previous highest frequency.

Step 28: Add +1 to the contents of memory F, F+1
is input into memory F.

Step 28': Set the valid bit data of RAM to 1
and move to step 20, after which rotation speed>VEL,
As long as F>FMAX, step 12 → 17 → 18
→ 26 → 27 → 28 → 20 → 21 → 2
Repeat 2-23.

Even if F > FMAX in the above operation, if the motor rotation speed is higher than the specified speed, the contents of memory F are increased by +1, the drive frequency is gradually increased, and the previous highest frequency of RAM is also increased. The rotational speed of the motor is updated (increased) in the same way, and the rotational speed of the motor is gradually decreased, and the rotational speed of the motor is controlled to become the specified speed.

In steps 12, 17 to 23, and 25 to 28 above, the motor is controlled to the specified speed, and the motor drive frequency at that time is higher than the frequency FMAX set in the RAM when the motor is started. At times,
The frequency is stored in RAM, and the actual highest frequency at which the motor is driven is stored in RAM.

In addition, in the process of increasing the speed of the motor when controlling the speed of the motor and gradually decreasing the driving frequency, when the driving frequency becomes the resonant frequency of the motor or a frequency near it, The above-mentioned frequency is not lowered below that level.

That is, the counter COU of FIG. 1 as described above.

is configured to count pulses from VCO during a period in which 0 is output from output PD of comparator PC2. In addition, the comparator PCz is configured to output O from the output PD for a short time according to the phase difference between the pulses of the inputs R and S, as the phase difference becomes zero, and as the motor approaches the resonance state, , the above comparator P
The configuration is such that the pulse phase to the inputs R and S of C2 approaches zero. Therefore, the count value of the counter C0UI decreases as the motor approaches the resonance state, and when the count value reaches or is close to the resonance state of the motor, it becomes less than the predetermined value $3. This state is detected by the comparator MCI, and when the motor resonates or near resonance, the output of the comparator MCI becomes 1, which is detected by the flip-flop DFF.
The output Q of DFF2 becomes 1. In addition, in response to the Q output 1 of the DFF2, the comparator CP4 also outputs 1, which is input to the input port PDO of the computer CPU.

Therefore, when the motor is in a resonance state or in the vicinity thereof, 1 is transmitted to the input port PDO, and in step 20 during the motor speed increase control process, F '' F +
P Do = F = F + 1 is made. Therefore, with speed increase control, F=F-1 is performed in step 19,
When the frequency reaches a resonance state or its vicinity after the frequency is decreased, +1 is added to F in step 20, and as a result, F=F-1+1=F, and the frequency decrease in step 19 is performed in step 20. When the frequency becomes at or near the resonant frequency, even if the motor rotation speed has not reached the specified speed, the frequency will be prevented from becoming any lower, and the motor drive frequency will eventually become It does not drop below the frequency at or near resonance. The reason for limiting the frequency when reducing the motor frequency in this way is that as shown in Figure 5, when the motor passes the resonant frequency f1 and the frequency drops below the resonant frequency, the rotation speed decreases rapidly. This is because such a phenomenon is prevented from occurring by the above-mentioned frequency restriction.

Also, when the motor is driven by a specified rotation amount during the speed control of the motor as described above, the memory C0
The contents of UNT become 0.

Therefore, in this case, the process moves to step 24.

Step 24: Output O from FBI.

As a result, the gates AN, , AN are closed, the application of the frequency voltage to the electrodes A and B is prohibited, the motor is stopped, and the first motor drive is completed.

After this, the step shifts to step 2 above.

Now, when driving the motor for the first time, steps 13 to 16,
Alternatively, steps 27-28' are executed and the valid bit of the RAM is set to 1 when the highest frequency of the RAM is changing from $FF.

Therefore, the highest frequency at which the motor was actually driven during the first motor drive is read out from the RAM in step 2.3 of the first motor drive, and output ports PAO~
The highest frequency from the previous time is outputted from the PA and inputted to the memory F, so that when the next time the motor is driven, the drive frequency at the time of starting the motor is designated and prepared to be the highest frequency at which the motor could actually be driven last time.

Therefore, when the next time the motor is driven, the start switch is turned on at a concave path (not shown) and the motor is controlled by executing each step after step 7, the drive frequency will start from the previous highest frequency. do.

Also, if the highest frequency that was actually able to drive the motor when the motor was driven immediately before is set as the driving frequency of the next motor, the motor will be able to rotate at that frequency, and this will change the driving frequency to $ The motor starts rotating immediately without the need for scanning from the FF.

Furthermore, even if the main switch SWI is turned off after the first motor drive, the contents of the RAM are retained, and even if the main switch SWI is turned on again and the program is executed from step 1, the contents of the RAM will be retained from the previous highest frequency. Driving will begin.

〔effect〕

As described above, in the present invention, the frequency at which the motor actually started rotating when the vibration wave motor was driven last time is set as the starting frequency for the next motor drive, and the desired speed is adjusted from this frequency. Since the frequency is shifted to the lower frequency direction, it is possible to gradually shift the frequency from the frequency that started the motor when it was used just before to the frequency direction that indicates the desired speed, and the motor runs smoothly.
Moreover, it can be started up in a short time.

In addition, although an electrostrictive element is shown as an electro-mechanical energy conversion element in the embodiment, a piezoelectric element may be used instead.

In addition, in the embodiment, the frequency at the time the motor starts rotating is memorized and this is set as the initial value for the next startup, but the frequency at the time the motor starts rotating is within a predetermined range. Memorize the frequency of or find it by calculation,
This may be set as the next initial value.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a control circuit for a vibration wave motor according to the present invention, and FIG. 2 is a configuration diagram showing an electrostrictive element arranged on a vibrating body of a vibration wave motor used in the present invention. Third
The figure is a waveform diagram for explaining the operation of the comparator PC2 shown in Figure 1, Figures 4(a) and (b) are explanatory diagrams showing the program flow built in the computer CPU of Figure 1, and Figure 5 is an explanatory diagram showing the program flow built in the computer CPU of Figure 1. It is an explanatory view explaining rotation control operation of a vibration wave motor of the present invention.

Claims (1)

[Claims] (1) Applying a frequency signal to an electric-mechanical energy conversion element arranged on the vibrating body to form a progressive vibration wave in the vibrating body,
A control circuit for a vibration wave motor that drives a moving object using the vibration waves includes a frequency adjusting means for gradually changing the frequency signal from a predetermined frequency toward a lower frequency when the motor is started, and detecting rotation of the motor. rotation detection means for
A frequency detection means is provided for detecting frequency information corresponding to a frequency when the start of rotation of the motor is detected by the rotation detection means when the frequency is being changed by the frequency adjustment means, the detection means A control circuit for a vibration wave motor, characterized in that an initial value of a frequency to be changed by the frequency adjustment means at the next time the motor is started is set based on frequency information detected by the vibration wave motor.