JP3198041B2 - Ultrasonic motor speed controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an elastic vibration generated by supplying an ultrasonic voltage to a piezoelectric vibrator that produces a piezoelectric effect as a driving source, and a moving body pressed by the piezoelectric vibrator generates a frictional force. The present invention relates to a speed control device for an ultrasonic motor that moves a driven body using a driving force obtained through the speed control device.

[0002]

2. Description of the Related Art Hitherto, a piezoelectric vibrator obtained by subjecting a ferroelectric substance to polarization processing has been used as a conversion element between electric energy (voltage, electric charge, etc.) and mechanical energy (displacement, strain, etc.). Due to the piezoelectric effect of the piezoelectric vibrating body, the piezoelectric vibrating body expands and contracts when a voltage is supplied, and a high-frequency voltage signal belonging to an ultrasonic region is supplied as a voltage signal, whereby the piezoelectric vibration The body generates elastic vibration of compression and expansion in accordance with the ultrasonic frequency of the voltage signal, and the moving body pressed by the piezoelectric vibrator rotates by the driving force obtained through the frictional force of the pressing force.

The frequency at which an output can be efficiently obtained with respect to the voltage signal supplied to the piezoelectric vibrator is near a resonance frequency fs at which the vibration amplitude increases as shown in FIG. It depends on the shape and material of the piezoelectric vibrator. Further, in order to generate a traveling wave that generates rotation in the piezoelectric vibrator, an electrode was divided into quarters of the wavelength λ in the piezoelectric vibrator and the direction of polarization was alternately changed in adjacent driving electrodes. Two kinds of voltage signals having a phase difference of π / 2 are supplied to the two-phase electrodes.

As shown in FIGS. 2 and 9, a driving device for the ultrasonic motor is a DC power source 4 and is driven by the DC power source 4 to transmit an ultrasonic voltage signal to the piezoelectric vibrator 1.
Driving means 51 for supplying one two-phase electrode 11a, 11b
And the ultrasonic motor 1 driven by the driving means 51. The driving unit 51 includes an oscillating unit 6 that oscillates a voltage signal having a required frequency, a phase control unit 71 that controls a phase difference between voltage signals supplied to the two-phase electrodes 11a and 11b, It comprises an amplitude adjusting means 81 for adjusting to a voltage signal.

Here, the phase difference control means 71 sets the phase difference between the voltage signal supplied to the two-phase electrodes 11a and 11b based on the one voltage signal and the other voltage signal to the one voltage signal by π. / 2, a reversing means 7b for reversing the ± sign of the phase difference for reversing the ultrasonic motor, and a voltage of an ultrasonic voltage signal supplied to the piezoelectric vibrator 11. Phase difference detecting means 7c for detecting a phase difference of a current and the two-phase electrode 1
It comprises a phase difference varying means 7d for changing the phase difference between the voltage signals supplied to 1a and 11b.

The signal detected by the phase difference detecting means 7c is input to a feedback means 91 via a line L2, and a control signal is supplied via a line L3 so as to maintain the phase difference at a constant value or within a certain range. And controls the frequency of the ultrasonic voltage signal oscillated from the oscillating means 6.

By the way, in such an ultrasonic motor device, a speed detecting means 10 such as an encoder for detecting the speed of the ultrasonic motor 1 is installed, and the speed is inputted to the feedback means 91 through a line L4, A control signal for oscillating an ultrasonic voltage signal having a predetermined speed by comparing the speed signal from the speed detecting means 10 with the speed command signal 1 including the inversion signal input via the line L1 in the feedback means 91. Is input to the oscillating means 6 via the line L3, and an ultrasonic voltage signal having a required frequency is oscillated and input to the phase difference means 7c.

[0008] Here, a voltage signal whose phase is shifted by π / 2 with respect to the voltage signal input by the phase difference means 7c is generated, and the voltage signal of the original phase is transmitted via a line L15 via a line L14. The signal is input to the reversing means 7b. Further, inversion is performed by changing the phase of the voltage signal input from the line L15 to 0 or ± π in accordance with an inversion command input from the feedback means 91 via the line L6. The original phase voltage signal input to the inverting means 7b via the line L14 is input directly to the amplitude adjusting means 8a via the line L16, and the speed command signal input via the line L8 by the feedback means 91. The amplitude is adjusted in accordance with the equation (1) and supplied to one electrode 11 a of the piezoelectric vibrating body 11.

On the other hand, the reversing means 7 is connected via a line L15.
The voltage signal which is input to b and the phase of which is changed by the inversion command signal is input to the phase difference varying means 7d via the line L17, and is input from the feedback means 91 to the phase difference varying means 7d via the line L7. The phase of the voltage signal is changed according to the speed command signal Vp and output to the amplitude adjusting means 8a. The amplitude adjusting means 8a adjusts the amplitude according to the speed command signal input via the line L8 by the feedback means 91. Then, it is supplied to another electrode 11b of the piezoelectric vibrator 11.

Thus, the electrode 11 of the piezoelectric vibrating body 11
The ultrasonic motor 1 is changed to a predetermined speed by a change in amplitude or a change in phase difference of the voltage signals supplied to the a and 11b.

As a conventional ultrasonic motor speed controller, there is an ultrasonic motor speed controller described in, for example, JP-A-6-237584. In the speed control device described in the above publication, the piezoelectric vibrator 11 is controlled based on a control signal from the feedback unit 91.
The speed of the ultrasonic motor 1 is varied by changing both the amplitude and the frequency of the ultrasonic voltage signal supplied to the two-phase electrodes 11a and 11b.

Further, based on the control signal from the feedback means 91, both the frequency of the ultrasonic voltage signal supplied to the two-phase electrodes 11a and 11b of the piezoelectric vibrator 11 and the phase difference between the ultrasonic voltage signals change. Thus, the speed of the ultrasonic motor 1 is varied. Here, when changing the amplitude or frequency of the ultrasonic voltage signal, it means that the ultrasonic voltage signals supplied to the two-phase electrodes 11a and 11b are both changed.

The two-phase electrode 1 of the piezoelectric vibrating body 11
The speed of the ultrasonic motor 1 is changed by setting the phase difference of the ultrasonic voltage signals supplied to 1a and 11b to π / 2 and changing the phase difference around π / 2.
The inversion of the ultrasonic motor is performed by reversing the ± sign of the voltage signal.

[0014]

However, the conventional speed control device as described above has the following problem in that simple and stable speed control is performed.

First, the change in the speed of the ultrasonic motor 1 does not become linear as shown in FIG. 11 with respect to the change in the amplitude of the ultrasonic voltage signal. To perform this, complicated speed control by the speed detecting means 10 and the feedback means 91 is required. Next, by changing the phase difference of the ultrasonic voltage signal supplied to the two-phase electrodes 11a and 11b around π / 2,
The speed of the ultrasonic motor 1 can be changed.

However, first, after the phase difference is shifted to π / 2, the phase difference is changed around π / 2. In order to reverse the rotation direction of the ultrasonic motor,
Since a circuit component for reversing the ± sign of the phase difference of the ultrasonic voltage signal is required, the number of circuit components increases.

Further, the frequency of the ultrasonic voltage signal is shown in FIG.
Although the speed of the ultrasonic motor 1 is changed by changing between the resonance frequency fs and the anti-resonance frequency fp as shown in FIGS. 10A and 10B, the admittance is changed as shown in FIG. When the characteristics are steep, the speed of the ultrasonic motor 1 greatly changes due to a slight change in the frequency, and the admittance characteristics between the resonance frequency fs and the anti-resonance frequency fp are not linear, so that the speed control is complicated. become.

For the above reasons, it is difficult to change the speed stably with the frequency control. Further, at the resonance frequency fs, which is the frequency at which the maximum output is obtained, the phase of the impedance of the piezoelectric vibrator suddenly changes and the ultrasonic motor may stop.
(A) and (B), a voltage signal in a frequency band in which the impedance phase of the piezoelectric vibrator, that is, the phase difference between the voltage and current of a voltage signal to be supplied is stable and the vibration amplitude of the piezoelectric vibrator is large. Must be supplied to the piezoelectric vibrator, and the lower limit frequency is set to be higher than the resonance frequency fs. Therefore, it cannot be driven at the maximum output frequency, and the maximum output value also changes rapidly due to a change in the admittance characteristic due to a temperature change or the like.

Therefore, when the speed of the ultrasonic motor 1 is varied by changing the frequency of the ultrasonic voltage signal, the change in the frequency of the ultrasonic motor 1 due to the change in the frequency is large. It is difficult to obtain a wide-range linear speed change, and in addition, the admittance characteristic moves right and left in FIG. 10A including the resonance frequency fs and the anti-resonance frequency fp due to a temperature change. Therefore, complicated speed control is required in consideration of performing a stable speed change with respect to a temperature change.

For this reason, a phase difference detecting means 7c for detecting a phase difference between a voltage and a current of the ultrasonic voltage signal supplied to the two-phase electrodes 11a and 11b of the piezoelectric vibrator 11 in response to a temperature change is provided. The phase difference between the voltage of the voltage signal supplied to the piezoelectric vibrator and the current is detected, and the signal from the phase difference detecting means 7c is input to the feedback means 91 to keep the phase difference at a constant value or within a constant range. There is a method of controlling the frequency of the ultrasonic voltage signal output from the oscillation circuit 6 as described above.

However, in the above method, a rapid change in speed due to a change in admittance with respect to a change in temperature can be suppressed. However, the phase difference detecting means 7c is required, and the structure of the feedback means 91 becomes complicated, resulting in an increase in cost. There is a problem of inviting.

[0022]

According to a first aspect of the present invention, there is provided an ultrasonic motor control device comprising: a piezoelectric vibrating body comprising two-phase electrodes;
A driving circuit that supplies a voltage signal having the same frequency and amplitude to each of the two-phase electrodes, the ultrasonic motor control device comprising : Voltage signal
A phase difference, an ultrasonic motor control apparatus characterized in that a phase difference generating means for varying the -π / 2~ + π / 2 at once.

According to a second aspect of the present invention, in the ultrasonic motor control apparatus, the driving means for detecting a frequency due to the vibration of the piezoelectric vibrator as a vibration voltage signal is provided based on the vibration voltage signal detected from the piezoelectric vibrator. 2. The ultrasonic motor control device according to claim 1, wherein a voltage signal is supplied to the piezoelectric vibrator.

The ultrasonic motor control device according to claim 3 is characterized by comprising an amplitude control means for varying the amplitude of the voltage signal towards that secure the front SL one of the voltage signals
An ultrasonic motor control device according to claim 1 .

According to a fourth aspect of the present invention , in the ultrasonic motor control device, the phase difference generating means includes an operational amplifier and a capacitor.
And a junction FET, and the internal resistance of the FET is K1
~ K3, with the capacitance of the capacitor as C
Phase angle when the transfer function immediately before the + terminal side is obtained
∠G (jω) = ∠ (K1 (C) · jω) − (∠ (1
+ K2 (C) / jω) + ∠ (1 + K3 (C) / jω))
2. The ultrasonic motor control device according to claim 1, wherein

According to a fifth aspect of the present invention , in the ultrasonic motor control device, the phase difference generating means may be configured such that the one terminal is connected to the negative terminal side.
Signal is input and the one voltage signal is
An operational amplifier whose signal is input via a capacitor,
A drain is connected between the non-inverting input terminal and the capacitor.
Source is connected to the source, and speed is
Ultrasonic motor control apparatus according to claim 1, characterized in that comprising a junction type FET which command signal is input.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) In Embodiment 1, in an ultrasonic voltage signal supplied to two-phase electrodes of the piezoelectric vibrator and having the same frequency and the same amplitude, the one voltage signal is used as a reference and the other voltage is used. The speed is changed by changing the phase of the signal with respect to the one voltage signal at a time around π / 2.

That is, by equalizing the amplitude and frequency of the two-phase ultrasonic voltage signal, the ultrasonic motor linearly covers a wide range with respect to a change in the phase difference between the two-phase ultrasonic voltage signals. Speed can be changed.

In the prior art, the phase difference between the two-phase ultrasonic voltage signals is first shifted to π / 2, and then the speed is changed by changing the phase difference around π / 2. That is, the voltage signals to be supplied to the piezoelectric vibrator are written as in equations (1) and (2), respectively: E1 (t) = A1 · sin (ω1 · t) (1) E2 (T) = A2 · sin (ω2 · t) (2) Here, A1 = A2, but the angular vibration frequency of the one voltage signal is ω1, and the angular vibration of the other voltage signal is Frequency ω
Assuming that the phase difference between the two phases is Δθ1, the phase of the one voltage signal at time t is ω1t and the phase of the other voltage signal is ω2t, so that ω2 · t = ω1 · t ± (π / 2 + Δθ1) −π / 2 ≦ Δθ1 ≦ 0 (3) Here, ± in the equation (3) indicates inversion.

However, in the present invention, instead of first performing the step of shifting the phase difference to π / 2, the equation (3) is used.
The phase difference π / 2 + Δθ1 is changed as a phase difference Δθ2 in equation (4) described later, and the phase difference becomes 0 or the speed becomes 0, and the driving direction is reversed at the phase difference 0 as a boundary. The phase difference is collectively determined by using -π / 2 to + π
By changing to / 2, an inversion function can be provided.

That is, ω2 · t = ω1 · t + Δθ2−π / 2 ≦ Δθ2 ≦ + π / 2 (4) Therefore, since the speed can be changed linearly with respect to the change in the phase difference, the speed can also be changed linearly with respect to the change in the speed command signal, and further, the speed can be varied with a simplified circuit configuration and also with inversion.

FIGS. 1, 2 and 3 show Embodiment 1 of the present invention.
It will be described based on. As shown in FIG. 2, as the ultrasonic motor, a stator 3 that generates a traveling wave by being supplied with a voltage signal of a frequency in an ultrasonic wave (20 KHz or more) region, and is pressed against the stator 3 with an appropriate pressure. Thus, the rotor 2 is driven by rotation.
Further, the stator 3 includes a piezoelectric vibrating body 11 that generates a traveling wave by an ultrasonic voltage signal supplied from a driving unit 52 described later, and an elastic body 3 a bonded to the piezoelectric vibrating body 11.
The rotor 2 is composed of a lining material 2b and a lining material 2 that effectively convert the traveling wave generated by the stator 3 into rotational motion by being pressed.
b, which is fixed to b and transmits the rotational motion to the external driven body
a. The piezoelectric vibrator 11 uses a barium titanate-based piezoelectric element or the like.

In the control apparatus for the ultrasonic motor, the driving means 51 is provided as shown in FIG. 1 together with the DC power supply 4 for operating the driving means 51. Further, a speed detecting means 10 for detecting the speed of the ultrasonic motor is provided, and a speed command voltage signal 1Vi1 including a speed signal Vs from the speed detecting means 10 and an inversion command for giving a predetermined speed is input. Means 92 are provided. In addition, an oscillating unit 6 that oscillates an ultrasonic voltage signal of an appropriate frequency to the piezoelectric vibrator 11 based on a control signal from the feedback unit 92 is provided as a component of the driving unit 52. Here, the configuration of the driving means 52 includes the oscillating means 6 for oscillating an ultrasonic voltage signal and two kinds of ultrasonic waves generated by the oscillating means 6 and supplied to the two-phase electrodes 11a and 11b of the piezoelectric vibrating body 11. A phase control unit 72 for controlling the phase of the voltage signal and an amplitude adjusting unit 82 for adjusting the amplitudes of the two types of ultrasonic voltage signals are further provided.

The phase control means 72 includes a phase difference detection means 7c for detecting the phase of the voltage and current of the ultrasonic voltage signal supplied to the piezoelectric vibrator 11, and the one of the two types of ultrasonic voltage signals. There is provided a phase difference generating means 7e which also serves as an inverting means, in which the phase difference relating the other ultrasonic voltage signal to the one ultrasonic voltage signal with respect to the ultrasonic voltage signal is collectively centered on π / 2. .

Next, the present configuration will be described with reference to FIG. 1 along the progress of the oscillating voltage signal. First, when a DC current is supplied from the DC power supply 4, an ultrasonic voltage signal is generated by the oscillating means 6 and input to the phase difference detecting means 7c. Here, the phase difference between the voltage and the current of the ultrasonic voltage signal input by the phase difference detection means 7c is detected, and the detected signal is input to the feedback means 92 via the line L2 so that the phase difference is within a certain range. By inputting a control signal for oscillating an internal frequency to the oscillating means 6 via a line L3, an ultrasonic voltage signal of a required frequency is oscillated from the oscillating means 6 and input to the phase difference detecting means 7c again. .

The frequency adjustment range of the ultrasonic voltage signal oscillated from the oscillating means 6 varies from the resonance frequency fs of the piezoelectric vibrator 11 to the anti-resonance frequency fp as shown in FIG.
Between. By the way, the ultrasonic voltage signal passing through the phase difference detecting means 7c is divided into a line L11 and a line L12, and the ultrasonic voltage signal passing through the line L11 is directly input to the amplitude adjusting means 8b and shown in the equation (1). After the amplitude is adjusted to the required maximum output A1, the voltage is input to one of the two-phase electrodes 11a of the piezoelectric vibrating body 11.

The ultrasonic voltage signal passing through the line L12 is input to a phase difference generating means 7e, and the phase difference generating means 7e performs speed control based on the speed control signal Vp input from the feedback means 92 via the line L9. In order to change the amplitude, the phase of the ultrasonic voltage signal is changed, and the amplitude is adjusted to the required maximum output A2 (= A1) shown in Expression (2) by the amplitude adjusting means 8b. Of the voltage signal having the same amplitude and the same frequency to be supplied to the two-phase electrodes 11a and 11b. Here, the operation of the phase difference generating means 7e will be described with reference to FIG.

Here, the resistors 21 and 22 shown in FIG.
Is an element that determines the amplification factor in the operational amplifier 23 that generates a phase difference, and the operational amplifier 2
The amplification factor in 3 is set to 1. Also, a phase difference is generated between the capacitor 24 and the junction type FET 25, and the
6, the offset adjustment and the like are performed. Here, FET2
Although a speed command signal is input from the gate side of 5, the gate voltage normally becomes a negative value, but in order to make it easier to control, the bias voltage is raised and the speed can be varied from 0V to several volts in the plus direction on the gate side. As described above, the source is basically grounded, and the variable resistor 26 is adjusted also as an offset adjustment amount.

Next, the transfer function immediately before the capacitor 24 and immediately before the + terminal side of the operational amplifier 23 is obtained to explain the occurrence of the phase difference, as shown in equation (5). Assuming that the electric capacity of the capacitor 24 is C, G (s) = K1 (C) · s / ((1 + K2 (C) · s) · (1 + K3 (C) · s)) (5) where s = Substituting jω, the phase angle becomes ∠G (jω) = ∠ (K1 (C)） jω)-(∠ (1 + K2 (C) ・ jω) + ∠ (1 + K3 (C) ・ jω)) (6) Where K1 to K3 are the internal resistance and the capacitance C of the capacitor 24 when the equivalent circuit of the FET is rewritten.
Is a coefficient according to This gives equations (5) and (6)
, The denominator is a differential element, where the phase advances by + π / 2 regardless of C and K1. Next, when looking at the numerator, it is a second-order delay element, and it can be seen that the phase can be changed from 0 to -π here.

That is, the phase difference in the phase difference generating means 7e can be changed from -π / 2 to + π / 2. In this manner, a traveling wave is generated in the piezoelectric vibrator 11 by elastic vibration due to the piezoelectric effect, and the ultrasonic motor 1 is driven to rotate.

The rotational speed of the ultrasonic motor 1 is obtained by transmitting the speed signal Vs detected by the speed detecting means 10 such as an encoder to the feedback means 9 through a line L4.
2 and compared with the speed command signal 1Vil, a speed control signal Vp for performing speed control in the phase difference generation means 7e is output via a line L9, and speed control is performed in the phase difference generation means 7e. .

As described above, in the first embodiment, in the ultrasonic voltage signal supplied to the two-layered electrode, the one ultrasonic voltage signal is used as a reference and the other ultrasonic voltage signal is used as the one ultrasonic voltage signal. On the other hand, by providing the phase difference generating means 7e for changing the phase difference collectively around π / 2, the phase difference is changed around π / 2 after the conventional phase difference is shifted to π / 2. As compared with the method, by inverting the method, the circuit configuration can be simplified, and the speed can be linearly changed over a wide range by the phase difference change.

(Embodiment 2) In Embodiment 2, the first embodiment
In the ultrasonic motor, the frequency due to the vibration of the piezoelectric vibrator is detected as a vibration voltage signal so that the change in the admittance characteristic due to the temperature change of the piezoelectric vibrator can be tracked to the change in the resonance frequency of the piezoelectric vibrator. Driving means for supplying a voltage signal to the piezoelectric vibrator based on the detected voltage signal.

Here, when the piezoelectric vibrator is driven by the driving means, the piezoelectric vibrator tends to vibrate near the natural frequency (resonant frequency) due to the resonance characteristics of the piezoelectric vibrator at the natural frequency. Therefore, a resonance frequency can be detected from the piezoelectric vibrator.

Further, since the voltage signal is tracked so that the frequency of the voltage signal can be maintained at the resonance frequency fs at which the maximum output is obtained, a more stable output can be obtained as compared with the related art. Therefore, by using the self-excited oscillation method, the speed becomes stable when the resonance frequency fs changes due to a temperature change or the like.
The change in speed due to the variable phase difference of the voltage signal is further stabilized, and the circuit configuration is simplified by eliminating the oscillation means and the like.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, components having the same functions as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the control device of the ultrasonic motor, the driving means 5
3 is provided with the DC motor 4 for operating the driving means 53 and the ultrasonic motor 1 as shown in FIG.
Here, a vibration voltage signal indicating a frequency due to the vibration of the piezoelectric vibrating body 11 is detected, and the driving means 53 is connected to the driving means 53 by a line L5 so that an ultrasonic voltage signal can be supplied to the piezoelectric vibrating body 11 based on the vibration voltage signal. Feedback will be given.

The driving means 53 has a phase control means 73 for controlling the phases of two types of ultrasonic voltage signals supplied to the two-phase electrodes 11a and 11b of the piezoelectric vibrator 11.
And an amplitude adjusting means 83 for adjusting the amplitudes of the two types of ultrasonic voltage signals. Further, the phase control means 73 sets the phase difference between the two types of ultrasonic voltage signals with respect to the one ultrasonic voltage signal with respect to the one ultrasonic voltage signal with respect to the one ultrasonic voltage signal at a center of π / 2. Only the phase difference generating means 7e, which also functions as the inverting means, is provided.

Next, the present configuration will be described with reference to FIG. 4 along the progress of the voltage signal. First, a DC current is supplied from the DC power supply 4 to the piezoelectric vibrator 11 of the ultrasonic motor 1 in the vicinity of a resonance frequency fs determined by a natural frequency of the piezoelectric vibrator itself and a constant of a circuit of the driving unit 53. Generates vibration. A vibration voltage signal due to the vibration generated in the piezoelectric vibrator 11 is detected and fed back to the driving unit 53 through a line L5, and an ultrasonic voltage signal is supplied to the piezoelectric vibrator 11 based on the vibration voltage signal. Incidentally, the oscillating voltage signal is supplied to a line L5 input to the phase control means 73 in the driving means 53.
And the amplitude adjusting means 8b are divided into a line L13 and a line L13.
The ultrasonic voltage signal passing through 13 is directly input to the amplitude adjusting means 8b and adjusted to the required maximum output A1 shown in the equation (1). Is input to one of the electrodes 11a.

The ultrasonic voltage signal passing through the line 5 is input to a phase difference generating means 7e in the phase control means 73, and the phase difference generating means 7e directly outputs a speed command signal 3Vi3 including an inversion command. In order to change the speed, the phase of the ultrasonic voltage signal is changed, and a phase difference is generated between the voltage signals supplied to the two-phase electrodes 11a and 11b. Here, the operation of the phase difference generating means 7e is the same as that of the first embodiment, and thus the detailed description is omitted.

Further, the ultrasonic voltage signal whose phase has been shifted by the phase difference generating means 7e is inputted to the amplitude adjusting means 8b and the amplitude A2 which becomes the required maximum output shown in the equation (2) is obtained.
After being adjusted to (= A1), the ultrasonic wave is applied to the other electrode 11b of the two-phase electrodes of the piezoelectric vibrator 11, whereby a traveling wave is generated in the piezoelectric vibrator 11 by elastic vibration, and the ultrasonic motor 1 is driven to rotate.

As described above, in the second embodiment, in the ultrasonic voltage signal supplied to the two-phase electrode, the other ultrasonic voltage signal is converted to the one ultrasonic voltage signal with reference to the one ultrasonic voltage signal. On the other hand, by providing the phase difference generating means 7e for changing the phase difference collectively around π / 2, the phase difference is changed around π / 2 after the conventional phase difference is shifted to π / 2. In contrast to the method, the circuit configuration is simplified by also inverting, and the method of changing the phase difference is simplified by also having the inversion, and the speed is linearly changed over a wide range by the phase difference change. Can be changed. Further, since the output is stable because of the self-excited oscillation method that does not require the oscillation means 6, the output can be stabilized against temperature changes without using the speed detection means 10, and the speed can be linearly detected over a wide range. Without using the means 10, the speed can be changed linearly over a wide range in a stable and stable manner against a temperature change and the like, and the phase difference detecting means 7c and the feedback means 92 in the first embodiment can be omitted.

( Example 1 of Example 3) In Example 1 of Example 3 , a piezoelectric vibrating body composed of two-phase electrodes and the same frequency and π /
An ultrasonic motor having at least a drive circuit for supplying a voltage signal having a phase difference of two, wherein the one voltage signal is fixed as a fixed-side voltage signal and the other voltage signal is changed as an adjustment-side voltage signal to change the amplitude. The speed is changed by providing the amplitude control means. That is, the fixed-side voltage signal can be expressed as Expression (7), and the adjustment-side signal can be expressed as Expression (8).

E1 (t) = A1 · sin (ω1 · t) (7) E2 (t) = A2 · sin (ω2 · t) (8) Here, if ω1 = ω2, ω2 · t = ω1 · t ± π
/ 2, and ± means inversion. Then, the speed is changed by changing A2 in the expression (8) at 0 ≦ A2 ≦ A1 without changing the expression (7) side at all. This allows
Since the speed changes linearly with the change in the amplitude of the adjustment-side voltage signal, the speed changes linearly even with a change in the speed command signal. Moreover, since the speed can be changed by changing only the amplitude of the adjustment-side signal, the speed control and the circuit configuration are simplified.

[0055] The premise Example 1 of the real施例3 of the present invention will be described with reference to FIGS. In the present embodiment, components having the same functions as those described in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

In the control device for the ultrasonic motor, the driving means 5
4 is provided with the DC motor 4 for operating the driving means 54 and the ultrasonic motor 1 as shown in FIG.
Further, a speed detecting means 10 for detecting the speed of the ultrasonic motor 1 is provided, and a speed signal Vs from the speed detecting means 10 and a speed command voltage signal 1Vi1 including an inversion command for giving a predetermined speed are input. Feedback means 93 is provided.

Further, an oscillating means 6 for oscillating an ultrasonic voltage signal of an appropriate frequency to the piezoelectric vibrator 11 based on a control signal from the feedback means 93 is provided as a component of the driving means 53. Here, the configuration of the driving means 54 is such that the oscillating means 6 for oscillating an ultrasonic voltage signal and the piezoelectric vibrating body 11 generated by the oscillating means 6 are used.
Phase control means 74 for controlling the phase of two types of ultrasonic voltage signals supplied to the two-phase electrodes 11a and 11b, and amplitude adjusting means 84 for adjusting the amplitudes of the two types of ultrasonic voltage signals. .

The phase control means 74 detects the phase of the voltage and current of the ultrasonic voltage signal supplied to the piezoelectric vibrator 11 and the phase difference detecting means 7c and the one of the two ultrasonic voltage signals. Phase difference means 7a for setting the phase difference of the other ultrasonic voltage signal with respect to the one ultrasonic voltage signal to π / 2 based on the ultrasonic voltage signal, and inverting means for inverting the signal by reversing the ± sign of the phase difference 7b is provided.

Next, the description of the present configuration will be made along the progress of the oscillating voltage signal with reference to FIG. First, when a DC current is supplied from the DC power supply 4, an ultrasonic voltage signal is generated by the oscillating means 6 and input to the phase difference detecting means 7c. Here, the phase difference between the voltage and the current of the ultrasonic voltage signal inputted by the phase difference detecting means 7c is detected, and the detected signal is fed back to the feedback means 93 inputted via the line L2 so that the phase difference is constant. A control signal for oscillating a frequency within the range is input to the oscillating means 6 via a line L3, an ultrasonic voltage signal of a required frequency is oscillated from the oscillating means 6, and input again to the phase difference detecting means 7c.

The frequency adjustment range of the ultrasonic voltage signal oscillated from the oscillating means 6 varies from the resonance frequency fs of the piezoelectric vibrator 11 to the anti-resonance frequency fp as shown in FIG.
Between.

The ultrasonic voltage signal passing through the phase difference detection means 7c is input to the phase difference means 7a, and the voltage signal whose phase is shifted by π / 2 is supplied via a line L15 to the signal of the original phase. Are separately output to the inversion means 7b via the line L14. The two types of ultrasonic voltage signals input to the inverting means 7b are changed according to an inversion command signal input from the input feedback means 93.
The direction of rotation is changed by reversing the ± sign of the phase difference between the types of ultrasonic voltage signals.

Here, the voltage signal of the original phase is inputted as a fixed-side voltage signal to the amplitude adjusting means 8b via the line L16, and the amplitude A which becomes the required maximum output shown in the equation (7) is obtained.
The adjustment-side voltage signal adjusted to 1 and having its phase changed to ± π / 2 by the inversion means 7b is input to the amplitude adjustment means 8c, and the amplitude is changed from 0 to the amplitude A2 which becomes the required maximum output from equation (8).
(= A1), the speed can be changed, and the two-phase electrode 11 of the piezoelectric vibrating body 11 can be changed.
a, 11b, the piezoelectric vibrator 1
A traveling wave is generated by the elastic vibration 1 and the ultrasonic motor 1 is driven to rotate. Here, the voltage signal amplitude adjusting means 8c forms a switching circuit by resistors 33 and 31 as shown in the circuit diagram of FIG.
Since the P-type power transistor 32 is complementarily symmetrically connected, it can be adjusted to a voltage signal having an amplitude corresponding to the control voltage + V. Therefore, the amplitude adjustment means 8c for the adjustment-side voltage signal has a speed command signal voltage Va2 (= A2). Then, the speed can be changed by changing the voltage between 0 ≦ Va2 ≦ A1.

The rotational speed of the ultrasonic motor 1 is obtained by transmitting the speed signal Vs detected by the speed detecting means 10 such as an encoder to the feedback means 9 via a line L4.
3 is compared with a speed command signal 1Vi1 including an inversion command input from a line L3, and outputs a speed control signal Va2 for performing speed control on the amplitude adjusting means 8c for the adjustment-side voltage signal. Then, speed control is performed.

As described above, in the first example of the third embodiment, 2
In the ultrasonic voltage signals supplied to the phase electrodes 11a and 11b, if one of the ultrasonic voltage signals is fixed as a fixed-side voltage signal and the other ultrasonic voltage signal is an adjustment-side voltage signal, only the adjustment-side voltage signal is used. In this method, the circuit configuration and speed control can be simplified, and the speed can be linearly changed over a wide range by changing only the amplitude of the adjustment-side voltage signal.

( Prerequisite Example 2 of Embodiment 3 ) In Premise Example 2 of Embodiment 3, in the ultrasonic motor of the embodiment, the admittance characteristic of the piezoelectric vibrator against the change of the admittance characteristic due to the temperature change of the piezoelectric vibrator is changed. A drive unit that detects a frequency due to the vibration of the piezoelectric vibrator as a vibration voltage signal to supply a voltage signal to the piezoelectric vibrator based on the detected voltage signal so that the piezoelectric vibrator can track the change in the resonance frequency. Use a self-excited vibration system.

Here, when the piezoelectric vibrating body is driven by the driving means in the same manner as in the first embodiment, the piezoelectric vibrating body is driven by the natural frequency (resonance characteristic) due to the resonance characteristics at the natural frequency of the piezoelectric vibrating body. (Vibration frequency), the resonance frequency can be detected from the piezoelectric vibrator. In addition, the tracking is performed so that the frequency of the piezoelectric vibrator can be maintained at the resonance frequency fs at which the maximum output is obtained, so that a more stable output than before can be obtained. Therefore, by using the self-excited oscillation method, the speed is stabilized when the resonance frequency fs changes due to a temperature change or the like, the speed change due to the variable amplitude of the voltage signal is further stabilized, and the circuit is eliminated by removing the oscillation means and the like. The configuration is also simplified.

[0067] The premise Example 2 real 施例3 of the present invention will be described with reference to FIG. In addition, in this premise example, the above-mentioned first to third embodiments are used.
Components having the same functions as the components described in 2 and the first premise are denoted by the same reference numerals, and the description thereof is omitted.

In the control device for the ultrasonic motor, the driving means 5
5 is provided with the ultrasonic motor 1 and the DC power supply 4 for operating the driving means 55 as shown in FIG.
Here, the driving means is detected by a line L5 so as to detect a vibration voltage signal indicating a frequency due to the vibration of the piezoelectric vibration body 11 and supply an ultrasonic voltage signal to the piezoelectric vibration body 11 based on the detected vibration voltage signal. This is fed back to 55. The driving means 55 includes a phase control means 75 for controlling the phases of two types of ultrasonic voltage signals supplied to the two-phase electrodes 11a and 11b of the piezoelectric vibrator 11,
Further, an amplitude adjusting means 84 for adjusting the amplitudes of the two types of ultrasonic voltage signals is provided.

In the phase control means 74, of the two types of ultrasonic voltage signals, the one ultrasonic voltage signal is fixed as a fixed-side voltage signal, and the other ultrasonic voltage signal is fixed as a control-side voltage signal. A phase difference means 7a for setting a phase difference to π / 2 and an inversion means 7b for inverting the phase difference by inverting ± signs are provided.

Next, the configuration will be described with reference to FIG. 7 along the progress of the voltage signal. First, a DC voltage is supplied from the DC power source 4 to the piezoelectric vibrating body 11 of the ultrasonic motor 1 so that the natural frequency of the piezoelectric vibrating body itself and a resonance frequency near the resonance frequency determined by the circuit constant of the driving unit 55 are increased. Generates vibration. A vibration voltage signal due to the vibration generated in the piezoelectric vibrator 11 is detected and fed back to the phase difference means 7a in the driving means 55 through a line L5, and based on the vibration voltage signal, the piezoelectric vibrator 11 is detected.
To supply an ultrasonic voltage signal.

Here, in the oscillating voltage signal fed back to the phase difference means 7a, a voltage signal whose phase is shifted by π / 2 is separated via a line L15, and a signal of the original phase is separated via a line L14. The reversing means 7b
Is output to The two types of ultrasonic voltage signals input to the inverting means 7c are configured to reverse the ± sign of the phase difference between the two types of ultrasonic voltage signals according to the inversion command signal input from the input feedback means 93. Changes the direction of rotation. Here, the voltage signal of the original phase is input as a fixed-side voltage signal to the amplitude adjusting means 8b via the line L16 and is adjusted to the amplitude A1 which becomes the required maximum output shown in the equation (7). ± π / 2 phase at 7b
Is input to the amplitude adjusting means 8c and the speed command signal 2Vi2 input from the line L10.
The speed can be changed by adjusting the amplitude from 0 to the amplitude A2 (= A1) which is the required maximum output from the equation (8) according to the equation (8), and the two-phase electrodes 11a, When input to the piezoelectric vibration member 11b, a traveling wave is generated in the piezoelectric vibration member 11 by elastic vibration, and the ultrasonic motor 1 is driven to rotate. Here, the description of the speed change in the amplitude adjustment means 8c for the adjustment-side voltage signal will be described in the first assumption.
It is omitted because it is the same as.

As described above, in the second example of the third embodiment,
In the ultrasonic voltage signals supplied to the phase electrodes 11a and 11b, if one of the ultrasonic voltage signals is fixed as a fixed-side voltage signal and the other ultrasonic voltage signal is an adjustment-side voltage signal, only the adjustment-side voltage signal is used. The method of adjusting the amplitude of the circuit can simplify the circuit configuration and the speed control, and can reduce the conventional 2
In contrast to a method in which both amplitudes of the voltage signals supplied to the phase electrodes are changed in the same manner, the speed can be linearly changed in a wide range by changing only the amplitude of the adjustment-side voltage signal. Further, the output may be stable due to the self-excited system which does not require the oscillating means 6, so that the speed detecting means 10
Therefore, the speed can be changed linearly over a wide range in a stable manner even if temperature is not used, and the phase difference detecting means 7c and the feedback means 93 in the third embodiment can be omitted.

(Embodiment 3 ) In the embodiment, in the two-phase voltage signal of the ultrasonic motor according to the premise example 1 , the other voltage signal is opposed to the one voltage signal with reference to the one voltage signal. The speed is changed by additionally providing a phase difference generating means for changing the phase difference collectively around π / 2.

That is, although the ultrasonic voltage signals supplied to the two-phase electrodes of the piezoelectric vibrator have the same frequency, the one voltage signal is fixed as a fixed-side voltage signal and the other voltage signal is adjusted to the adjustment-side voltage signal. Assuming that the voltage signal is a voltage signal, a means for changing the speed by providing an amplitude control means for changing the amplitude of the adjustment-side voltage signal, and a phase difference between the fixed-side voltage signal and the adjustment-side voltage signal centered on π / 2. The speed can be changed by providing together a phase difference generating means for changing the speed at once.

Here, in the same manner as in the first embodiment , linear speed control over a wide range can be performed for the speed change due to the change in the phase difference. As for the speed change due to the variable amplitude, linear speed control can be performed in the same manner as in the first embodiment. However, in the case of the speed change only by the phase difference variable or the speed change only by the amplitude variable, depending on the use condition of the ultrasonic motor as the control motor, the phase difference variable minimum unit Δθ by the phase difference variable and the amplitude variable In some cases, the speed change with respect to the amplitude variable minimum unit ΔV is larger than the required minimum speed change amount. For this reason, it is necessary to make a finer speed change, and a high speed resolution may be required especially at a low speed.

Therefore, by performing the variable amplitude and the variable phase difference together, the speed can be linearly changed with respect to the speed command signal, and the speed resolution at the time of low speed can be finely taken. Fine and stable speed control can be performed over a wide range. In addition, the third embodiment
In the case of the above, since the phase difference was fixed to π / 2,
Means for making the phase difference π / 2 and means for reversing the ± sign of the phase difference for reversing the motor are required. However, if the variable by the phase difference in the first embodiment is performed, a circuit is required. The structure can be simplified.

A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the first and second embodiments and
Components having the same functions as the components described in the premise examples 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

In the control device for the ultrasonic motor, the driving means 5
6 is provided with the ultrasonic motor 1 and the DC power supply 4 for operating the driving means 56 as shown in FIG.
Further, a speed detecting means 10 for detecting the speed of the ultrasonic motor is provided, and a speed signal Vs from the speed detecting means 10 and a speed command voltage signal 1Vi1 which gives a predetermined speed and includes an inversion command are input. Means 94 are provided. In addition, the piezoelectric vibrating body 11 is controlled based on a control signal from the feedback means 94.
Oscillating means 6 for oscillating an ultrasonic voltage signal having an appropriate frequency
Are provided as components of the driving means 56. Here, the configuration of the driving means 56 is such that the oscillating means 6 oscillates an ultrasonic voltage signal and is supplied from the oscillating means 6 to the two-phase electrodes 11a and 11b of the piezoelectric vibrating body 11.
Phase control means 7 for performing phase control of various types of ultrasonic voltage signals
2, and an amplitude adjusting means 84 for adjusting the amplitudes of the two types of ultrasonic voltage signals. The phase control means 72 has the same configuration as that of the first embodiment, and has a phase difference detection means 7c for detecting the phase of the voltage and current of the ultrasonic voltage signal supplied to the piezoelectric vibrating body 11, and the two types of ultrasonic voltage A phase difference generating means 7e having a phase difference with respect to the one ultrasonic voltage signal with respect to the one ultrasonic voltage signal and a phase difference centering on .pi. / 2 at the same time, and also serving as an inverting means. Is provided.

Next, the present configuration will be described with reference to FIG. 8 along the progress of the oscillating voltage signal. First, when a DC current is supplied from the DC power supply 4, an ultrasonic voltage signal is generated by the oscillating means 6 and input to the phase difference detecting means 7c. Here, the phase difference detecting means 7c detects the phase difference between the voltage and the current of the ultrasonic voltage signal input thereto, and inputs the detected signal to the feedback means 94 via the line L2, so that the phase difference is within a certain range. A control signal for oscillating an internal frequency is output to the oscillating means 6 via a line L3, and an ultrasonic voltage signal of a required frequency is oscillated from the oscillating means 6 and input to the phase difference detecting means 7c again.

The frequency adjustment range of the ultrasonic voltage signal oscillated from the oscillating means 6 ranges from the resonance frequency fs of the piezoelectric vibrator 11 to the anti-resonance frequency fp as shown in FIGS. 10A and 10B. Between. By the way, the ultrasonic voltage signal passing through the phase difference detecting means 7c is divided into a line L11 and a line L12, and the ultrasonic voltage signal passing through the line L11 is inputted as it is to the amplitude adjusting means 8b and becomes an amplitude which becomes a required maximum output. After being adjusted to A1, it is fixed as a fixed-side voltage signal and input to one of the two-phase electrodes 11a of the piezoelectric vibrating body 11. In addition, line L12
The ultrasonic voltage signal passing through is input to the phase difference generating means 7e as an adjustment-side voltage signal, and the phase difference generating means 7e responds to the speed control signal Vp input from the feedback means 94 via the line L9. The phase of the adjustment-side voltage signal is changed to generate a phase difference between the voltage signals supplied to the two-phase electrodes 11a and 11b.

Further, the adjustment-side voltage signal, the phase of which has been changed by the phase difference generating means 7e, is input to the amplitude adjusting means 8c according to the speed command signal Va2 input from the feedback means 94 via the line L10. The speed can be varied by changing the amplitude A2 of the adjustment-side voltage signal from 0 to A1. After the amplitude is adjusted by the amplitude adjusting means 8c for the adjustment-side voltage signal, the piezoelectric vibrator 11 is adjusted.
Is input to the other electrode 11b of the two-phase electrodes, the two-phase electrodes are supplied with an ultrasonic voltage signal having the same frequency and a phase difference and an amplitude difference from each other.
That is, a traveling wave is generated in the piezoelectric vibrator 11 by elastic vibration due to the piezoelectric effect, and the ultrasonic motor 1 is driven to rotate.

The rotational speed of the ultrasonic motor 1 is obtained by inputting the speed signal Vs detected by the speed detecting means 10 such as an encoder to the feedback
A speed control signal Vp for performing speed control in the phase difference generating means 7e and a speed control signal for performing speed control in the vibration adjusting means 8c for adjusting the voltage signal are compared with the speed command 1Vi1 input from Step 1. Va2 is output to each means.

As described above, in the third embodiment, the two-phase electrode 1
In the ultrasonic voltage signals supplied to 1a and 11b, if one of the ultrasonic voltage signals is fixed as a fixed-side voltage signal and the other ultrasonic voltage signal is an adjustment-side voltage signal, the adjustment adjusts the voltage signal to the fixed-side voltage signal. By providing the phase difference generating means 7e for changing the phase difference collectively around π / 2 with respect to the voltage signal, the conventional phase difference is shifted to π / 2 after the phase difference is shifted to π / 2. In contrast to the method of changing the phase difference centering on 2, the circuit configuration is simplified by inversion, and the speed can be linearly changed over a wide range by the phase difference change.

Further, by changing only the amplitude of the adjustment-side voltage signal, the speed can be linearly changed in comparison with the conventional method of changing both the amplitudes of the voltage signals supplied to the two-phase electrodes in the same manner. That is, by combining the phase difference change and the amplitude change of only the adjustment-side voltage signal, not only can a high speed resolution be obtained at a low speed, but also fine and stable speed control can be performed over a wide range including at a high speed.

Here, the variable execution order and which one of the phase difference change and the amplitude change of only the adjustment-side voltage signal is used for the sign adjustment depend on the speed control method, the use condition of the ultrasonic motor 1, and the like. Furthermore, when the self-excited driving method is adopted as in the second embodiment and the second premise example in using the third embodiment, the circuit configuration and the speed control can be simplified. Although the above embodiments have been described with reference to the ultrasonic motor using the ring-shaped piezoelectric vibrator, the present invention can be applied to any ultrasonic motor of a progressive type.

[0086]

According to a first aspect of the present invention, there is provided an ultrasonic motor comprising at least a piezoelectric vibrator comprising two-phase electrodes and a drive circuit for supplying a voltage signal having the same frequency and amplitude to each of the two phases. The other voltage signal with respect to the one voltage signal with reference to the one voltage signal.
The speed is changed by providing a phase difference generating means for changing the phase difference of the pressure signal from -π / 2 to + π / 2 at a time. Here, the speed of the ultrasonic motor can be linearly changed over a wide range in response to a change in the phase difference between the two-phase ultrasonic voltage signals.

However, in the prior art, the speed is changed by first shifting the phase difference between the two-phase ultrasonic voltage signals to π / 2 and then changing the phase difference around π / 2. 1) to (3). However, in the present invention, the phase difference π / 2 + Δθ1 in the equation (3) is collectively changed as the phase difference Δθ2 in the equation (4) instead of first performing the step of shifting the phase difference to π / 2.

Further, when the phase difference is 0 and the speed is 0,
By utilizing the fact that the driving direction is reversed at the boundary of 0 phase difference and changing the phase difference from -π / 2 to + π / 2 at once, an inversion function can be provided. It can be expressed as follows. As described above, in the ultrasonic motor speed control device, the speed can be linearly changed over a wide range by changing the phase difference, so that the speed can be changed linearly even with a change in the speed command signal. Further, since the phase variable portion can be collectively performed, the circuit configuration can be simplified, and there is an effect that the speed can be stably changed by a simple speed control mechanism.

According to a second aspect of the present invention, in the ultrasonic motor according to the first aspect, the driving means for detecting a frequency due to the vibration of the piezoelectric vibrating body includes the two-phase motor based on a voltage signal detected from the piezoelectric vibrating body. It is provided to supply a voltage signal to the electrode. Here, when the piezoelectric vibrating body is driven by the driving means, the piezoelectric vibrating body tends to vibrate near the natural frequency (resonant frequency) due to resonance characteristics at the natural frequency of the piezoelectric vibrating body. The resonance frequency can be detected from the piezoelectric vibrator.

Conventionally, in response to a change in the resonance frequency of the piezoelectric vibrating body due to a change in the admittance characteristic of the piezoelectric vibrating body due to a change in temperature of the piezoelectric vibrating body or a change in a load pressing the moving body, The phase difference between the voltage and the current of the voltage signal supplied to the vibrating body is detected by a phase difference detection unit, and the detected phase difference is higher than a resonance frequency at which the phase difference becomes a constant value or a phase difference value within a certain range. This is a separately excited system provided with an oscillating means for oscillating a frequency voltage signal.

However, in the present invention, the self-excited driving means is provided which can track a change in the resonance frequency of the piezoelectric vibrator due to a change in the admittance characteristic of the piezoelectric vibrator. That is, the oscillation means and the phase difference detection means, which are conventionally required, and the feedback means to the oscillation means can be eliminated.

Since the voltage signal is tracked so that the frequency of the voltage signal can be maintained at the resonance frequency fs at which the maximum output is obtained, a stable output can be obtained. That is, the speed is stabilized when the resonance frequency fs changes due to a temperature change or the like, and the speed change due to the variable phase difference of the voltage signal is further stabilized. There is an effect that means can be eliminated and speed control can be simplified by simplifying the circuit configuration.

In the third aspect, the ultrasonic motor according to the first aspect is used.
The speed is changed by providing amplitude control means for fixing the one voltage signal and changing the amplitude of the other voltage signal. Conventionally, when changing the speed by changing the amplitude of the voltage signal, the amplitude of the two-phase voltage signal is changed to be the same for the two phases. However, in this method, the speed has a linear relationship with the amplitude change. In order to perform stable speed control without change, complicated speed control was required.

However, in the present invention, when one of the voltage signals is a fixed-side voltage signal and the other is an adjustment-side voltage signal, only the amplitude A2 in the equation (8) is changed by a change in the amplitude of the adjustment-side voltage signal. This changes the speed linearly. Therefore, since the speed can be changed linearly by changing only the amplitude of the adjustment-side voltage signal, the speed can be changed linearly with respect to the change of the speed command signal. It can be simplified because it can be performed only by using

[0095]

[0096]

[0097]

[0098]

That is, in claim 3, the one voltage signal is fixed as a fixed-side voltage signal and the other voltage signal is used as an adjustment-side voltage signal, and amplitude control means for changing the amplitude of the adjustment-side voltage signal is provided. And a phase difference generating means for collectively changing the phase difference of the adjustment-side voltage signal with respect to the fixed-side voltage signal from -π / 2 to + π / 2 . Here, the speed change due to the change of the previous SL retardation can linear speed control over a wide range, and may be linear conformal speed control the speed change by the phase difference variable.

However, in the case of the speed change only by the phase difference variable or the speed change only by the amplitude variable, depending on the use condition of the ultrasonic motor as the control motor, the speed with respect to the phase difference variable minimum unit Δθ by the phase difference variable is changed. In some cases, the change in speed and the speed change with respect to the amplitude variable minimum unit ΔV due to the amplitude change are larger than the required minimum speed change amount. For this reason, it is necessary to make a finer speed change, and a high speed resolution may be required especially at a low speed. Therefore, by performing the variable amplitude and the variable phase difference together, the speed can be changed linearly with respect to the speed command signal,
Further, not only can the speed resolution at a very low speed be obtained finely, but also the speed can be finely and stably controlled over a wide range including at a high speed.

[0101] In addition, in the case of fixing the previous Symbol phase difference to π / 2
In order to perform the inversion of the motor, both means for making the phase difference π / 2 and means for reversing the ± sign of the phase difference are required. By performing the variable by the phase difference, the circuit configuration of the phase control part can be simplified. Therefore, the overall circuit configuration is simplified, and the speed control is different from the conventional speed control based on the combination of variable speeds.

[Brief description of the drawings]

FIG. 1 is a main configuration diagram (part 1) of an ultrasonic motor speed control device according to the present invention.

FIG. 2 is a perspective view of a main part of the ultrasonic motor according to the present invention.

FIG. 3 is a circuit diagram of a phase difference generating means in the ultrasonic motor speed control device according to the present invention.

FIG. 4 is a main configuration diagram (part 2) of the ultrasonic motor speed control device according to the present invention.

FIG. 5 is a main configuration diagram (part 3) of the ultrasonic motor speed control device according to the present invention.

FIG. 6 is a circuit diagram of an amplitude adjusting unit in the ultrasonic motor speed control device according to the present invention.

FIG. 7 is a main configuration diagram (part 4) of the ultrasonic motor speed control device according to the present invention.

FIG. 8 is a main part configuration diagram (part 5) of the ultrasonic motor speed control device according to the present invention.

FIG. 9 is a configuration diagram of a main part of a conventional ultrasonic motor speed control device.

FIG. 10A is a diagram illustrating a relationship between the frequency of a voltage signal supplied to a piezoelectric vibrator and admittance characteristics. FIG. 3B is a diagram illustrating a relationship between a frequency of a voltage signal supplied to the piezoelectric vibrator and a logarithmic value of impedance, and a relationship between a frequency of the voltage signal and a phase difference between a voltage and a current.

FIG. 11 is a diagram illustrating the relationship between the amplitude and the speed of an ultrasonic voltage signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic motor 2 Rotor 2a Rotating body 2b Lining material 3 Stator 3a Elastic body 4 DC power supply 6 Oscillation means 7a Phase difference means 7b Inversion means 7c Phase difference detection means 7d Phase difference variable means 7e Phase difference generation means 8a Amplitude adjustment means 8b Amplitude adjusting means 10 Speed detecting means 11 Piezoelectric vibrator 11a Electrode 11b Electrode 21 Resistance 22 Resistance 23 Operational amplifier 24 Capacitor 25 FET 31 Transistor 32 Transistor 33 Resistance 53 Driving means 54 Driving means 74 Phase control means 84 Amplitude adjusting means 92 Feedback means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (5)

(57) [Claims] 1. An ultrasonic motor control device comprising: a piezoelectric vibrating body comprising two-phase electrodes; and a drive circuit for supplying a voltage signal having the same frequency and amplitude to each of the two-phase electrodes. The one voltage signal is based on the one voltage signal.
, The phase difference of the other voltage signal with respect to
Ultrasonic motor control apparatus characterized in that a phase difference generating means for varying a ~ + π / 2. 2. A driving unit for detecting a frequency due to the vibration of the piezoelectric vibrator as a vibration voltage signal supplies a voltage signal to the piezoelectric moving body based on the vibration voltage signal detected from the piezoelectric vibrator. The ultrasonic motor control device according to claim 1, wherein: 3. The power supply for fixing the one voltage signal.
That the amplitude control means for changing the amplitude of the pressure signal is provided.
The ultrasonic motor control device according to claim 1, wherein: 4. The method according to claim 1, wherein said phase difference generating means is connected to an operational amplifier.
Capacitor and junction type FET, and inside the FET
The resistance is K1 to K3 and the capacitance of the capacitor is C.
When the transfer function immediately before the + terminal side of the pair amplifier is found
Is characterized by satisfying ∠G (jω) = ∠ (K1 (C) · jω)-(∠ (1 + K2 (C) / jω) + ∠ (1 + K3 (C) / jω)). The super according to claim 1,
Sonic motor controller. 5. The phase difference generating means includes:
While one voltage signal is input, the one terminal is
Op signal is input through a capacitor
And a drain between the non-inverting input terminal and the capacitor.
The source is connected to ground,
And a junction type FET where the speed command signal is input to the
The ultrasonic motor control according to claim 1, wherein
apparatus.