JP2801229B2 - Vibration type motor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving device for a vibration type motor (vibration wave motor).

[Conventional technology]

2. Description of the Related Art Conventionally, when controlling the number of revolutions in a driving device of a vibration type motor (vibration wave motor), a method of adjusting the driving frequency has been adopted. In this method of controlling the number of revolutions by changing the frequency, when the speed control is performed by a micro computer, the number of revolutions is designated as a digital value from the computer, and the digital value is once converted into an analog signal by a D / A converter. It is conceivable to convert the driving frequency to a value corresponding to the set value by using an oscillator that oscillates according to this voltage.

[Problems to be solved by the invention]

However, since the vibration type motor (vibration wave motor) has a very fast response to the change in the rotation speed with respect to the frequency change, it is necessary to finely change the driving frequency. Changing the value one step at a time does not allow a smooth transition of the rotational speed.

[Means for Solving the Problem] The present invention according to claim 1 has been made in view of the above, and has a setting circuit for setting digital data;
A frequency signal forming circuit for forming a frequency signal having a frequency corresponding to the data set by the setting circuit; and a frequency voltage having a different phase according to the frequency signal from the frequency signal forming circuit is applied to the electromechanical energy conversion element portion. In the vibration type motor device that excites the vibrating body and obtains a driving force, an oscillation period in which a frequency signal is formed by the data without changing data set in the setting circuit during one cycle,
The data set in the setting circuit is changed to different data during the one cycle, and the data is fixed by providing control means for providing an oscillation period for forming a frequency signal by the changed data during the one cycle. In addition to the normal frequency set, an intermediate frequency can be set by changing the data.

According to a second aspect of the present invention, there is provided a vibration type motor device comprising an oscillation circuit which oscillates at a frequency corresponding to the digital data set by the setting circuit, as the configuration of the frequency signal forming circuit. It is.

According to a third aspect of the present invention, as the configuration of the frequency signal forming circuit, a digital-to-analog converter for converting digital data set by the setting circuit into an analog signal is provided, and the oscillation circuit converts the analog signal to the analog signal. An object of the present invention is to provide a vibration type motor device configured to oscillate at an appropriate frequency.

According to a fourth aspect of the present invention, the control means alternately performs the data change between the first data and the second data as the change to the different data during the one cycle. The present invention provides a mold motor device.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of a vibration type motor (vibration wave motor) driving device according to the present invention.

In the figure, 1 is a microcomputer, 2 is a D / A converter connected to the output port of the microcomputer 1 and D / A converting a value set in the output port, 3
Is an operational amplifier whose non-inverting input terminal is connected to the output of the D / A converter and whose inverting input terminal is connected to the resistor 22; 19 is a base connected to the output of the operational amplifier 3;
Transistor connecting 22; 18 is a transistor connecting the collector to the collector of the transistor 19; 20 is a transistor connecting its base to the base of the transistor 18; these transistors 18, 20
Constitutes a current mirror circuit. 24 is a capacitor connected to the collector of the transistor 20; 4 is a comparator connected to the-input terminal of which a constant voltage Vc is applied and + terminal is connected to the output terminal of the capacitor 24; 21 is connected in parallel to the capacitor 24; , Its base resistance 23
Is a transistor connected to the output of the comparator 4 via the. In the above configuration, the condenser 24 has D / A
A current having a current value corresponding to the output of the converter 2 is supplied and charged. When the charge level of the capacitor 24 reaches Vc, the comparator 4 inverts and sends a high-level output (hereinafter, referred to as H), turning on the transistor 21 to discharge the charge of the capacitor 24. As a result, the output of the comparator 4 is inverted from H to a low level output (hereinafter, referred to as L), turning off the transistor 21 and restarting the charging of the capacitor 24. Hereinafter, by repeating the above operation, a pulse having a frequency corresponding to the output level of the D / A converter 2 is output from the comparator 4. Reference numerals 5 and 6 denote D-type flip-flops which connect the clock terminal CK to the output of the comparator 4. The D input of the flip-flop 5 is connected to the Q output of the flip-flop 6, and the D input of the flip-flop 6 is connected to the flip-flop 5.
Connected to the output. These flip-flops output pulses that are 90 degrees apart from their Q (flip-flop 5) and output (flip-flop 6) outputs. 7 is an exclusive OR gate, 8 and 9 are AND gates, 10 and 11 are amplification circuits, 13 and 14 are matching coils, 15 is a vibration type motor (vibration wave motor), and an electric motor is mounted on a stator (not shown). A piezoelectric body as a mechanical energy conversion element is provided. Reference numerals 16 and 17 denote drive electrodes for applying a drive voltage to the piezoelectric body, respectively.

 The operation of the circuit shown in FIG. 1 will be described.

As described above, the capacitor 24 is charged with a current value corresponding to the output of the D / A converter 2 as shown in FIG. 2A, and the output of the comparator 4 is a pulse having a frequency corresponding to the output of the converter 2 (FIG. 2B). ) Is formed. In synchronization with the pulse of the comparator 4, the Q output of the flip-flop 5 and the output of the flip-flop 6 form a 90 ° phase-shifted rectangular wave as shown in FIGS.

When L is applied to the exclusive OR gate 7 from the output port of the microcomputer 1, the gate 7 passes the output of the flip-flop 5 as it is. When the AND gates 8 and 9 are open, the electrodes 16 and 17 are driven with different phases by 90 ° according to the outputs of the flip-flops 5 and 6 via the amplification circuits 10 and 11 and the coils 13 and 14. When a voltage is applied, the vibration type motor (vibration wave motor) rotates at a speed corresponding to the output of the D / A converter 2. When H is applied from the computer 1 to the exclusive OR gate 7, a pulse obtained by inverting the output of the flip-flop 5 is output, and the rotation direction is reversed.

Since the vibration type motor (vibration wave motor) 15 is configured as described above, the digital signal output from the micro computer 1 is D / A converted, and further converted to a frequency, amplified and driven. Although it is inherently impossible to control the number of revolutions more finely than the change in the minimum bit of the converter 2, the present invention enables more precise control by the following method.

FIG. 3 is a one-wave charging waveform of the capacitor 24 shown in FIG. 2A. In the figure, f ₀ is the charging characteristic when the digital data input to the D / A converter is D (n), and f ₁ is the charging characteristic when the digital data input to the D / A converter is D (n + 1). It is a charging characteristic. Now, when data is to t ₁ one cycle to the output of the capacitor 24 reaches Vc when D (n), the data at time t ₃ about half of the period from D (n) D (n + 1) , The charging characteristic for the capacitor 24 changes from time t ₃ to f ₀
Off switched to f ₁ from. Therefore, in this case, data D
Intermediate time between one cycle t ₁ and t ₂ for (n) and D (n + 1)
At t _4, the voltage of the capacitor 24 reaches Vc,
The same effect can be obtained as when the resolution of the D / A converter is increased.

Also, if about 3/4 of the time t ₆ of about 1/4 hour t ₅ and t ₁ of t ₁ with respect to the period t ₁ performed the data switching, the effect is obtained that it is further increased resolution.

FIG. 4 illustrates the above effect, wherein A is the same voltage waveform across the capacitor 24 as in FIGS. 2A and 3A. B~E are a diagram showing a change in frequency f with respect to time T, the frequency of the time t _0, respectively the frequency of the time t _0, t ₈ and f _1. f ₁ −f ₀ is a frequency change when the bit of the D / A converter is switched.

FIG. B shows a simple switching of the D / A converter by one bit at t ₈ ′, and FIG. C shows that the D / A converter is switched from t ₄ ′ to t ₈ ′ by half the period t of FIG. Bit switched. That is, the resolution of the D / A converter is apparently increased by one bit.

Figure D is t ₂ 'from t _4' until the period t _1/4, t 4 'from t _6'
In this case, the D / A converter is switched by one bit in 1/2 time from t ₆ ′ to t ₈ ′ in 3/4 time. This has the effect of increasing the apparent resolution of the D / A converter by 2 bits.

FIG. E shows a further half of the control, which has the effect of increasing the resolution of the D / A converter by 3 bits.

FIG. 5 shows a control flow of the micro computer 1 for controlling the D / A converter, and FIG.
The processing when the frequency is changed by 1/2 bit every eight oscillation waveforms of FIG. As shown in FIG. 1, the output of the comparator 4 is connected to the CK inputs of the D flip-flops 5 and 6, while being connected to the interrupt input terminal of the microcomputer 1. When the comparator 4 is inverted, the output of the microcomputer 1 is changed. Is generated, and the flow of FIG. 5 is executed each time an interrupt occurs.

 Hereinafter, the control flow of FIG. 5 will be described.

[Step 1] The value of the memory in the RAM (not shown) of the micro computer 1 is incremented by one.

[Step 2] When the count value reaches 16, the flow branches to step # 8. Otherwise, the flow branches to step # 3.

[Step 3] Output D (n) to the D / A converter.

[Step 4] If the count value is 8 or more, go to # 5; otherwise, go to # 7.
Branch to

[Step 5] Wait 1/2 時間 of the half of the oscillation period t corresponding to the data D (n) determined in Step 3.

[Step 6] D (n + 1) is output to the D / A converter.

[Step 7] Enable the interrupt and end the interrupt processing.

The count value becomes 7 by the operation of the above steps 1 to 7.
Until data D (n) from computer 1
Is input to the D / A converter 2, the oscillation operation at cycles t ₁ corresponding to the data D (n) is carried out 7 times, after step 5 and 6 is executed. Thus, half the charging of the capacitor 24 of the current value corresponding to data D (n) at step 3 and 5 in the oscillating operation of the eighth after the relative period t ₁ corresponding to the data D (n) time t _1/2 After that, the data is switched from D (n) to D (n + 1), and the charging is continued until the output reaches the output Vc. Therefore, the output of the condenser 24 at cycle t ₄ as described above is to repeat the oscillation operation at cycles t ₄ reaches Vc in the oscillating operation of the eighth after. Doing oscillation at the period t ₄ 8 times step proceeds to 8 after, data at step 8,9 D (n + 1) is set, the count value is cleared at step 10. Therefore, the subsequent eight oscillation oscillating in period t ₂ in accordance with the data D (n + 1) is performed, the period becomes possible to vary fine step for each oscillation of 8 times, achieve a smooth rotation speed variation You can do it.

With the configuration as described above, the resolution of the D / A converter can be apparently increased, and a wide range of frequency changes can be changed in fine frequency steps.

Note that the control flow in FIG. 5 is an example in which the frequency is changed every eighth shot. However, when performing the rotation speed control according to the set value, the frequency is changed by the data D (n) according to the set rotation speed. A mode for determining and a mode for switching data D (n) to D (n + 1) on the way as described above may be provided, and the above two modes may be selected according to the set rotation speed.

[Effects of the Invention] As described above, in the present invention, the operation of changing the data for determining the frequency to different data in one cycle is periodically repeated, so that the frequency is fixed and the frequency is determined. There is an effect that a frequency that is more specific than that can be set.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a vibration wave motor driving device according to the present invention, FIG. 2 is a waveform diagram for explaining the operation of the circuit shown in FIG. 1, and FIGS. FIG. 5 is an explanatory diagram showing a program of an operation control flow according to the present invention. 1. Microcomputer 2. D / A converter

Claims (4)

(57) [Claims] A setting circuit for setting digital data; a frequency signal forming circuit for forming a frequency signal having a frequency corresponding to the data set by the setting circuit; Are applied to the electro-mechanical energy conversion element section to excite the vibrating body to obtain a driving force.
An oscillation period in which a frequency signal is formed by the data without changing the data set in the setting circuit during the cycle, and changing the data set in the setting circuit to different data during the one cycle; A vibration-type motor device comprising a control means for providing an oscillation period for forming a frequency signal based on data changed during a cycle, wherein the frequency is changed more finely than a change unit of digital data. 2. The vibration type motor device according to claim 1, wherein said frequency signal forming circuit has an oscillation circuit which oscillates at a frequency corresponding to the digital data set by said setting circuit. 3. A digital-to-analog converter for converting digital data set by the setting circuit into an analog signal is provided, and the oscillation circuit oscillates at a frequency corresponding to the analog signal. Item 3. A vibration type motor device according to item 2. 4. The apparatus according to claim 1, wherein said control means alternately changes data between the first data and the second data as a change to different data during the one cycle. Or the vibration type motor device according to 3.