JPH0213277A - Drive circuit for ultrasonic linear motor - Google Patents

Abstract

PURPOSE:To improve resonance efficiency of a piezoelectric vibrator by additionally providing a drive circuit with a circuit, which applies voltage of a frequency out of the resonance frequency to the piezoelectric vibrator in a condition that its temperature is always raised to a saturation temperature and stops the drive. CONSTITUTION:A driving circuit of an ultrasonic linear motor is provided with a select switch 11, frequency select circuit 13, high frequency oscillator 15 and a power amplifier 17, and an output line 18 of the driving circuit is connected to a vibrator 1 constituting a mover 4. A frequency voltage applying circuit, which applies voltage of a frequency out of the resonance frequency to advance drive legs 3a, 3b to right and left driving and stopping the vibrator 1 in a condition that its temperature is always raised to a saturation temperature, is built in said frequency select circuit 13. Hence in a stop position of the select switch 11, the voltage of frequency is applied to the vibrator 1 through the high frequency oscillator 15 from said applying circuit, when a vibrator temperature reaches the saturation temperature, the select switch 11 is placed, for instance, in a right advance position, and drive is started.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic linear motor comprising a vibrator driven by an alternating current or direct current pulse power source and a drive leg made of an elastic body connected to the vibrator. The present invention relates to a drive circuit.

BACKGROUND OF THE INVENTION Various examples of motors using ultrasonic vibrators have been proposed in the past, and as an example, Japanese Patent Laid-Open No. 148384/1984 describes a vibrating piece to which vibration is applied by a vibrator and the vibrator. and a contact body in surface contact with the vibrator, the vibrator applying vibration in a direction normal to a contact surface between the contact body and the vibrator, and forming a constant angle with respect to the normal direction. A configuration example of a vibration wave motor including another vibrator that applies vibration in a direction is disclosed. According to such a configuration, it is possible to generate elliptical motion in the vibrating element by combining vibrations in two different directions, and to cause relative movement between the running surface and the vibrating element.

Furthermore, as an example of using another ultrasonic vibrator or a near motor, as shown in FIG. drive legs 3a, 3b formed of a pair of elastic bodies protruding from both ends of the back side in a vertical direction and in a direction opposite to the vibrator 1;
A structure in which the mover 4 is formed by the following can be considered. 5a in the figure.

5b is a lead wire for applying a specific frequency voltage to the bipedal vibrator 1.

According to such a configuration, when a specific frequency voltage is applied to the vibrator 1 from a drive circuit (not shown) via the lead wires 5a and 5b, longitudinal vibration is excited in the vibrator 1, and this longitudinal vibration is excited. The vibration is transmitted through the base 2 made of an elastic body to the pair of drive legs 3a.
, 3b, and an elliptical vibration, which is a combination of the flexural vibration of the elastic body and the longitudinal vibration, is excited in the drive legs 3a, 3b. At this time, by making the resonance frequencies of the pair of driving legs 3a and 3b different, a phase difference occurs in the vibrations of both driving legs 3a and 3b, and the circular vibration is transmitted from the pair of driving legs to the running surface 6. The drive legs 3a, 3b and the running surface 6
The movable element 4 can be caused to travel along the running surface 6 by the frictional force between the movable element 4 and the travel surface 6. In the illustrated example, the driving legs 3a and 3b have different thicknesses E and F, respectively, which makes the resonance frequencies of the driving legs 3a and 3b different. Furthermore, since the moving direction of the moving element 4 can be changed to either the left or right by changing the frequency and voltage of the AC power source, the moving element 4 can be moved in any desired direction.

Problems to be Solved by the Invention However, such conventional ultrasonic linear motors, particularly the configuration example described in Japanese Patent Application Laid-open No. 148384/1984, have two vibrators that vibrate in different directions. In addition to the disadvantage that the cost increases because it is necessary to set up a vibrator and apply voltages with different phases to each vibrator, the circuit configuration for driving becomes complicated and the manufacturing process is complicated. There was a problem with this.

On the other hand, in the case of the configuration example shown in FIG. 15, since the drive frequency for moving the vibrator 1 to the right or left has a high temperature dependence, the mover 4 is immediately driven to run under all temperature conditions. The problem was that there were times when it was not possible to do so.

That is, the vibrator 1 starts to raise its temperature from the outside air temperature at a specific speed due to self-heating immediately after applying a predetermined frequency voltage, and the resonant frequency for driving the movable element 4 also changes with the temperature. , the drive circuit must be set in advance so that the resonant frequency applied to the vibrator 1 changes in accordance with the temperature. Therefore, the configuration of the drive circuit becomes complicated and it cannot be used outside of a predetermined temperature range. There is a drawback that the moving operation of the mover 4 is no longer performed. In other words, the mover 4 will not start running unless a certain period of time has elapsed since the application of a predetermined frequency voltage to the vibrator 1 and the temperature of the vibrator l has risen to a predetermined temperature or higher. In order to continue, the relationship between the resonance frequency and the temperature is required to be within a predetermined range, and it is impossible for the mover 4 to run outside the above range. .

Furthermore, if normal positive and negative sinusoidal voltages are applied to the vibrator 1 for a long period of time, the positive and negative voltages induce rapid polarization and reversal of the piezoelectric element that constitutes the vibrator 1, and the self-heating effect of the vibrator 1 becomes large. In addition, the amount of residual displacement at high temperatures becomes small, resulting in a reduction in resonance efficiency.

Therefore, the present invention solves the problems of the conventional driving means of an ultrasonic linear motor, eliminates the temperature dependence of the vibrator when the moving element is running, and makes it possible to As soon as a predetermined frequency voltage is applied, the moving element starts running, and even during long running, the amount of heat generated by the transducer is kept small, the residual displacement of the piezoelectric element is kept large, and the resonance efficiency is improved. It is an object of the present invention to provide a drive circuit for an ultrasonic linear motor that can be improved.

Means for Solving the Problems In order to achieve the above object, the present invention includes a base made of an elastic body, and a pair of drive legs that project vertically from both ends of the base and have mutually different resonance frequencies. and a piezoelectric vibrator or an electrostrictive vibrator that is fixed to the base or between the pair of driving legs and excites the vibration of the pair of driving legs, and the piezoelectric vibrator or electrostrictive vibrator In a configuration comprising a drive circuit that moves the drive leg to the right or to the left based on the difference in resonance frequency by applying a predetermined frequency voltage to the child, first, according to claim 1, the drive circuit includes a drive circuit. Applying a frequency voltage that deviates from the resonance frequency at which the foot moves to the right or left to stop the movement of the mover while keeping the piezoelectric vibrator or electrostrictive vibrator constantly heated to its saturation temperature. It is configured as a drive circuit for an ultrasonic linear motor with an attached circuit, and according to claim 2, means for detecting a temperature value of a piezoelectric vibrator or an electrostrictive vibrator when a frequency voltage is applied to the vibrator is provided. On the other hand, the drive circuit has a configuration in which a frequency voltage selection circuit is attached to the drive circuit to select a frequency voltage suitable for a resonance frequency at which the drive foot moves to the right or left under the temperature condition based on the detected temperature value. .

Furthermore, according to claim 3, a positive voltage is supplied to the drive circuit for increasing the amount of residual displacement of the piezoelectric vibrator or electrostrictive vibrator when application of the frequency voltage to the piezoelectric vibrator or electrostrictive vibrator is stopped. Claim 4: The structure includes a voltage generator.
A frequency voltage application circuit that applies a constant DC bias voltage to the piezoelectric vibrator or electrostrictive vibrator to the drive circuit to maintain the amount of residual strain in the piezoelectric vibrator or electrostrictive vibrator at high temperatures. The configuration of the drive circuit is as follows.

According to the drive circuit for an ultrasonic linear motor according to claim 1, the frequency voltage application circuit applies a frequency deviating from the resonant frequency at which the drive foot moves to the right or left to the piezoelectric vibrator or the electrostrictive vibrator. Since the movement of the mover is stopped while the voltage is applied and the temperature of the piezoelectric vibrator or electrostrictive vibrator is constantly raised to the saturation temperature, the piezoelectric vibrator or electrostrictive vibrator is always kept at the saturation temperature. Therefore, when a frequency voltage for causing the drive leg to run is applied to the vibrator, the movable element can immediately start running at the same time as the voltage is applied.

Moreover, the above-mentioned claim 2. ? According to the drive circuit of the Mi sonic linear motor No. 8, when a frequency voltage is applied to the piezoelectric vibrator or the electrostrictive vibrator, the final temperature value of the vibrator is detected by the detection means, and the frequency voltage selection circuit Based on this detected temperature value, a frequency voltage that matches the resonance frequency at which the driving leg constituting the transducer moves to the right or left under this 4 degree condition is selected, and this selected frequency voltage is applied to the transducer. Therefore, regardless of the magnitude of the temperature value during operation of the vibrator, the desired running motion can be obtained immediately, and the temperature dependence of the piezoelectric vibrator or electrostrictive vibrator can be eliminated. This effect is brought about.

Furthermore, according to the drive circuit according to claim 3, when the application of the frequency voltage to the vibrator is stopped, a voltage obtained from a voltage generator that always generates a positive voltage is applied to the vibrator, thereby suppressing the vibration. The residual displacement of the child can be increased, and the resonance efficiency of the mover can be improved.

Further, according to the drive circuit according to claim 4, since a positive DC bias voltage is always applied to the vibrator, voltages in the plus and minus directions are alternately applied like a normal sine wave. Compared to , the heat generation m of the vibrator itself is small,
In addition to the effect of making it difficult for the frequency voltage to deviate from a predetermined frequency range, the amount of distortion in the vibrator at low and high temperatures is approximately the same amount in the positive and negative directions centering on the positive bias voltage. This has the effect of maintaining normal operation.

Embodiments Hereinafter, various embodiments of an ultrasonic linear motor drive circuit according to the present invention will be described in detail with reference to the drawings, with the same reference numerals assigned to the same components as in the conventional structure.

FIG. 1 shows an embodiment of the present invention as set forth in claim 1, in which 11 is a select switch, 13 is a frequency selection circuit, 15 is a high frequency oscillator 117 is a power amplifier, , an output line 18.18 derived from the power amplifier 17 is connected to a vibrator l constituting the mover 4. The movable element 4 shown in FIG.
Piezoelectric vibrator or strain vibrator l fixed between 3a and 3b
(hereinafter abbreviated as oscillator 1).
The structure of the mover 4 may be that shown in FIG. 15 above.

The base portion 2 and the drive legs 3a, 3b are made of an elastic material that can transmit vibrations well, such as aluminum, brass, stainless steel, iron, glass material, duralumin, or a composite material thereof.

In addition, the vibrator 1 is composed of a laminated piezoelectric element or an electrostrictive element, and in addition to the above, a single plate piezoelectric or electrostrictive vibrator, or a single plate piezoelectric or electrostrictive vibrator and an elastic vibrator can be used. A combination of so-called Langevin oscillators or the like can be used. When a driving frequency voltage is applied to this vibrator 1, it vibrates at a frequency corresponding to the frequency of the frequency voltage, and this vibration causes the driving legs 3a,
3b, the driving legs 3a, 3b can be caused to travel along the running surface 6.

The select switch 11 is on the right row of the mover 4.

This is a switch for selecting either stop or left row, and the frequency selection circuit 13 has the function of determining the drive frequency to be supplied to the vibrator l according to the instruction from the selection switch 11. Further, the high frequency oscillator 15 is connected to the frequency selection circuit 13.
The power amplifier 17 amplifies the sine wave oscillation output from the high frequency oscillator 17 and supplies this oscillation output to the vibrator l.

- Figure 2 is a graph showing the relationship between the temperature when moving the moving element 4 and the frequency of the sine wave output from the high-frequency oscillator 15, and the graph ■ is when moving the moving element 4 to the right. It shows the frequency characteristic of
8KIIz, and as the temperature rises, the frequency and temperature are in an inversely proportional relationship.

Graph ■ shows the frequency characteristics when moving the movable element 4 to the left. Similarly, when the temperature of the vibrator 1 is 30°C,
Kllz, iQQ is 57KIlz at °C, and as with the case of rightward movement, the resonant frequency and temperature are in an inversely proportional relationship as the temperature rises. The broken line 8.8 in the figure is the mover 4
It shows the area where it is possible to drive the vehicle.

On the other hand, FIG. 3 is a graph showing the relationship between the time (minutes) that elapses after a predetermined frequency voltage is applied to the vibrator 1 and the temperature of the vibrator l. When 1 minute has passed after the start of application, the temperature of vibrator 1 reaches 90°.
The temperature reaches 100°C (saturation temperature) in about 3 minutes. Therefore, when applying a specific frequency voltage to the vibrator 1,
After a certain period of time has elapsed since the start of application, the t temperature of the vibrator 1 is within the range of a predetermined temperature (30°C in the illustrated example) to the saturation temperature (100°C in the illustrated example) for the vibrator l. By applying the predetermined frequency voltage shown in FIG. 2, the moving element 4 can be moved to the right or left.

In view of the frequency characteristics and temperature characteristics of the vibrator l shown in FIGS. 2 and 3 above, the frequency selection circuit 1 in the first embodiment
3, a frequency voltage that is different from the resonance frequency at which the drive legs 3a and 3b constituting the mover 4 move to the right or left is applied, and the vibrator l is driven with the temperature raised to the saturation temperature at all times. It has a built-in frequency voltage application circuit that stops it.

The operation of the embodiment having such a configuration will be explained below. That is, when the select switch 11 is in the stop position, a voltage of 20K is applied to the vibrator 1 from the frequency voltage application circuit built in the frequency selection circuit 13 via the high frequency oscillator 15.
A frequency voltage of Hz is applied. This 20 KHz is a frequency voltage that deviates from the resonance frequency when the drive legs 3a, 3b to which the vibrator 1 is fixed moves to the right or left (the area outside the broken lines 8, 8 in FIG. 2). Even in such a case, the temperature of the vibrator 1 rises rapidly as shown in Fig. 3, reaching 90°C one minute after the start of application, and saturating after about three minutes.) ! ! However, as mentioned above, the frequency voltage of 20 Kllz does not fall within the resonant frequency region shown by the broken lines 8 and 8 in Fig. 2, so the mover 4 remains in a stopped state. .

Next, suppose that the select switch 11 is turned to the right position.
Since the temperature has reached 00°C, the frequency selection circuit 13 instructs the high frequency oscillator 15 to output a frequency voltage of 88K II2. Then, the high frequency oscillator 15
A frequency voltage of 86 HIz is outputted from the oscilloscope, and this frequency voltage is amplified by the power amplifier 17 and applied to the vibrator l of the movable element 4, so that the movable element 4 immediately starts moving to the right. In this operation, the vibration of the vibrator l is first transmitted to the drive legs 3a and 3b as a deflection vibration, and an elliptical vibration, which is a combination of the vibration and the deflection vibration, is generated at the tips of the drive legs 3a and 3b. Since the driving legs 3a, 3b are excited and have different resonance frequencies, a phase difference in vibration occurs between the driving legs 3a, 3b, causing the elliptical vibration and the driving legs 3a, 3b and the running surface 6. Due to the frictional force between them, the mover 1 starts moving to the right. Note that the movement relationship of the mover 4 can be adjusted by changing the voltage value of the applied frequency voltage.

Next, when the select switch 11 is turned to the left position, the oscillator 1 is at the saturation temperature 1 as described above.
Since the temperature has reached 00°C, the frequency selection circuit 13 outputs 57KI to the high frequency oscillator 15! 7 frequency voltage to be output. Then, a frequency voltage of 57 KIIz is output from the high frequency oscillator 15, and this frequency voltage is amplified by the power amplifier 17 and applied to the vibrator l of the moving element 4, thereby causing the driving legs 3a, 3 that constitute the moving element 4 to
b immediately starts moving to the left based on the driving principle described above.

The frequency voltage applied to the vibrator 1 when the select switch 11 is in the stop position is not limited to the front Fa20Kllz, but may be any other frequency voltage as long as it is a value that deviates from the resonant frequency at which the driving ff13a, 3b can run. Needless to say, it is fine.

FIG. 4 shows an embodiment of the present invention as set forth in claim 2, and shows the same constituent parts as the embodiment of the invention as set forth in claim 1. It is indicated with a symbol. That is, 11 is a select switch, 40
19 is a CPU (microcomputer) that determines the frequency voltage to be supplied to the vibrator l, and 19 is a D/A converter that converts the frequency of the frequency voltage selected by the CPU 40 into an analog signal.

15 is a high frequency oscillator, and 17 is a power amplifier.

An output line 1818 derived from the power amplifier 17 is connected to the vibrator 1 constituting the mover 4. Furthermore, a thermocouple 21 is attached to the vibrator l, and an output line 23.23 derived from this thermocouple 21 is input to a thermocouple amplifier 25, and further fed back to the CPU 40 via a signal line 27. ing. That is, thermocouple 2
1 and the thermocouple amplifier 25 form means for detecting the temperature value of the vibrator 1 when a frequency voltage is applied to the vibrator 1.

The above-mentioned CPIJ 40 has a built-in frequency voltage selection circuit that selects a frequency voltage suitable for the resonance frequency at which the drive leg moves to the right or left under various degrees of rotation of the vibrator 1.

The effects of the configuration of this embodiment are as follows. That is, the thermocouple 21 constantly detects the temperature value of the vibrator 1,
This temperature value is fed to the CPU 40 via the thermocouple amplifier 25. On the other hand, the relationship between the frequency applied to the vibrator 1 and the temperature value (the graph explained in FIG. A frequency voltage for moving the mover 4 to the right or left in accordance with the temperature value is selected from the table data and the D/A is performed.
Output to converter 19. Then, after this frequency voltage is converted into an analog signal by the D/A converter 19, it is input to the high frequency oscillator 15, which oscillates a sine wave of the frequency selected by the CPU 40, and the power amplification 317 is the high frequency oscillator. The oscillation output of 17 is amplified and this oscillation output is sent to the oscillator l.
supply to. As a result, the vibration of the vibrator 1 is started, and the movable element 4 can be moved to the right or left based on the driving principle described above. Therefore, regardless of the magnitude of the temperature value when the vibrator 1 is in operation, the desired running operation is immediately performed, and the temperature dependence of the vibrator 1 in the operation can be made.

FIG. 5 shows an embodiment of the present invention as set forth in claim 3, and the same components as in the embodiment of the invention as set forth in claim 2 are given the same reference numerals. It is attached and displayed. That is, 11 is a select switch, 40 is a CPU that selects the frequency voltage to be supplied to the vibrator l, and 19 is a C
A D/Δ converter that converts the frequency of the frequency voltage selected by the PU 40 into an analog signal, 15 a high frequency oscillator, 17 a power amplifier, 29 a voltage generator that always supplies a positive voltage, and the power amplifier A changeover switch 31 is provided between the high frequency oscillator 15 and the voltage generator 29. This changeover switch 31 is controlled on/off by a control line 33 output from the CPU 40. Further, an output line 18.18 led out from the power amplifier 17 is connected to the vibrator 1 constituting the mover 4.

Figure 6 is a graph showing the relationship between the temperature of the vibrator 1 and the amount of residual displacement of the vibrator 1 corresponding to the temperature. That is, it is known that the polarization direction of the piezoelectric element constituting the vibrator 1 is normally disturbed when driven by applying positive and negative voltages, and in particular, when a positive and negative sine wave is applied for a long period of time, the direction of polarization is disturbed. Although the amount of residual displacement at the minus side temperature shown in the figure is large, as the temperature of the vibrator 1 increases, the amount of residual displacement becomes extremely small, and the movement of the movable element 4 deteriorates. In the example of FIG. 6, when the vibrator 1 reaches 100° C., the residual displacement becomes O. Therefore, in the third embodiment, when moving the mover 4 to the right or to the left based on the above-described operating principle, the select switch 11 is moved to the right or to the left, and the control line from the CPU 40 is 33, switch the changeover switch 31 to the high frequency oscillator 15 side,
After converting the frequency voltage selected by the CPU 40 into an analog signal by the D/A converter 19, the high frequency oscillator 15 oscillates a sine wave of the selected frequency, and this sine wave is amplified by the power amplifier 17 to generate vibrations. While supplying the frequency voltage to the moving element 1, when stopping the application of the frequency voltage to the moving element 4, the select switch 11 is set to the stop position and at the same time the CPU 40
The selector switch 31 is switched to the voltage generator 29 side via the control line 33. Then, the positive voltage supplied from the voltage generator is input to the vibrator 1 via the power amplifier 17, the disturbance in polarization due to the sine wave is corrected, the residual displacement of the vibrator I is increased, and the movable element 4 can be normalized. That is, to summarize the operation of the third embodiment, when the application of the frequency voltage to the vibrator 1 is stopped, the voltage generation '
By applying the positive voltage obtained from a29 to the vibrator 1, the amount of residual displacement of the vibrator 1 can be increased, and the resonance efficiency can be increased.

FIG. 7 shows an embodiment of the invention as set forth in claim 4, and the same components as in the first embodiment are denoted by the same reference numerals. That is, 11 is a select switch, 13 is a frequency selection circuit, 15 is a high frequency oscillator, 35 is a DC bias generator that always generates the above DC bias voltage, and 37 is the output of the high frequency oscillator 15 and the output of the DC bias generator 35. This is an adder that adds Reference numeral 17 denotes a power amplifier, and output lines 18 and 18 derived from the power amplifier 17 are connected to the vibrator 1 constituting the movable element 4.

According to such a configuration, when the mover 4 is moved to the right or to the left, when the select switch 11 is turned to the right or to the left, the frequency selection circuit 13 selects a predetermined value as in each of the above embodiments. A frequency voltage is selected and a normal sine wave 41 shown in FIG. 8 is supplied from the high frequency oscillation PJ15. On the other hand, the DC bias generator 35 always outputs a positive DC bias voltage 39 shown in FIG. Therefore, when this DC bias voltage 39 and the sine wave 41 are added by an adder 37, a positive bias voltage 43 is obtained as shown in FIG. This bias voltage 43 is applied to the vibrator 1 via the power amplifier 17, and the movable element 4 starts moving to the right or to the left.

The operation of the above embodiment is as follows. In other words, in the sine wave 41 that has been commonly used in the past, since voltages in the positive and negative directions are alternately applied to the vibrator 1, the polarization of the piezoelectric element constituting the vibrator 1 is rapidly reversed. As shown in Fig. 13, the residual strain ff1 (μ@) of the vibrator l is large when the driving voltage is O, as shown in Fig. 13, while the heat generation of the vibrator l increases. When the vibrator 1 is at a high temperature, the amount of residual strain at the driving voltage O becomes small as shown in FIG. 14, and when the voltage is negative, it becomes elongated, and the movement of the movable element 4 at high temperatures deteriorates. However, in the case of this embodiment, as shown in FIG. 11, the complete collapse of the vibrator 1 at low temperatures is caused by the positive bias, as shown by the bold line G in the same figure. 1, the amount of distortion in the transducer 1 is approximately the same amount in the plus and minus directions with the pressure 43 as the center, and even when the transducer 1 is at high temperature, the amount of distortion in the transducer 1 is as shown in the thick line in the figure, as shown in Fig. 12. As shown, since it is distorted by approximately the same m in the plus and minus directions around the positive bias voltage 43,
It can increase the resonance efficiency and activate the motor movement to maintain normal operation. Therefore, in the case of the fourth embodiment,
The amount of residual strain in the vibrator 1 at high temperatures can be increased, and the vibrator 41 expands and contracts in accordance with the shape of the positive bias voltage 43, thereby normalizing the operation of the movable element 4. Furthermore, since the applied voltage is not one in which positive and negative voltages are applied alternately like a normal sine wave, the amount of heat generated by the vibrator 1 itself is small, and the applied frequency voltage is not within a predetermined frequency range. It becomes difficult to deviate,
This brings about the effect that the moving operation of the mover 4 proceeds smoothly.

Effects of the Invention As explained in detail above, the drive circuit for an ultrasonic linear motor according to the present invention has a base made of an elastic body, and a motor that protrudes vertically from both ends of the base and that mutually has a resonant frequency. A movable element is constituted by a different pair of drive legs and a piezoelectric vibrator or an electrostrictive vibrator fixed to the base or between the pair of drive legs to excite vibration of the pair of drive legs, and the piezoelectric vibration According to claim 1, first of all, according to claim 1, there is provided a drive circuit which moves the drive leg to the right or to the left based on a difference in resonance frequency by applying a predetermined frequency voltage to a child or an electrostrictive vibrator. A frequency voltage that stops driving the piezoelectric vibrator or electrostrictive vibrator by constantly raising the temperature of the piezoelectric vibrator or electrostrictive vibrator to the saturation temperature by applying a frequency voltage that is different from the resonance frequency at which the drive leg moves to the right or left to the drive circuit. The drive circuit for an ultrasonic linear motor is configured with an application circuit, and according to claim 2, means for detecting a temperature value of a piezoelectric vibrator or an electrostrictive vibrator when a frequency voltage is applied to the vibrator. At the same time, the drive circuit is provided with a frequency voltage selection circuit which selects a frequency voltage suitable for a resonance frequency at which the drive foot moves to the right or left under this temperature condition by feeding the detected temperature value. Further, according to claim an, the drive circuit is configured to increase the amount of residual displacement of the piezoelectric vibrator or electrostrictive vibrator when the application of a frequency voltage to the piezoelectric vibrator or electrostrictive vibrator is stopped. According to a fourth aspect of the present invention, the drive circuit is configured to apply a constant DC bias voltage to the piezoelectric vibrator or the electrostrictive vibrator, so that Since the drive circuit is configured to include a frequency voltage application circuit that maintains the amount of residual strain in the piezoelectric vibrator or electrostrictive vibrator, the following effects are brought about.

That is, according to the ultrasonic linear motor drive circuit according to claim 1, when the frequency voltage application circuit is applied to the piezoelectric vibrator or the electrostrictive vibrator, the driving leg is always shifted from the resonant frequency at which it moves to the right or to the left. Since a frequency voltage is applied, the drive of the piezoelectric vibrator or electrostrictive vibrator is stopped with the temperature raised to the saturation temperature at all times. When a voltage is applied, the moving element can immediately start running at the same time as the voltage is applied.

According to the drive circuit for an ultrasonic linear motor according to the second aspect, the temperature value of the vibrator when the frequency voltage is applied to the vibrator is fed back to the frequency voltage selection circuit, thereby selecting the frequency voltage. Under these temperature conditions, the circuit selects a frequency voltage that matches the resonant frequency of the driving legs that make up the moving element moving to the right or left, and supplies this selected frequency voltage to the oscillator, so that the oscillator operates. Regardless of whether the temperature value is high or low at the time, the desired running operation can be performed immediately and the temperature dependence can be eliminated.

Further, according to the drive circuit according to the third aspect, when moving the movable element to the right or left, a sine wave of a selected frequency is oscillated by a high frequency oscillator, and this sine wave is supplied to the vibrator. On the other hand, when the moving element stops running, by manually applying a positive voltage obtained from a voltage generator to the vibrator, the disturbance in polarization due to the sine wave is corrected, and the residual displacement m of the vibrator is increased. It is possible to normalize the operation of the mover. Thereby, the resonance efficiency of the mover can be improved.

Further, according to the drive circuit according to claim 4, since the frequency voltage applied to the vibrator is a positive DC bias voltage, voltages in the plus and minus directions are applied alternately like a normal sine wave. In addition to the effect that the amount of heat generated by the vibrator itself is small compared to the above voltage, making it difficult for the frequency voltage to deviate from the predetermined frequency range, the amount of strain in the vibrator at low and high temperatures increases the bias voltage of the pressure. Since the distortion is approximately the same amount in the plus and minus directions around the center, a great effect can be obtained in that the normal operation of the motor can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the ultrasonic linear motor drive circuit according to claim 1 of the present invention, and FIG. 2 is a graph showing the frequency characteristics of the vibrator employed in the present invention. , FIG. 3 is a graph showing the temperature rise characteristics of the same vibrator, FIG. 4 is a block circuit diagram showing an embodiment according to claim 2 of the present invention, and FIG. 5 is a graph showing the temperature rise characteristic of the same vibrator. A block circuit diagram showing an embodiment according to claim 3, FIG. 6 is a graph showing the relationship between the temperature of the vibrator and the amount of residual displacement, and FIG. 7 is an embodiment according to claim 4 of the present invention. 8, 9, and 10 are graphs showing examples of applied voltage in the embodiment described in item 4 above, and 11.
Figures 12 and 12 are graphs showing the temperature characteristics of the embodiment described in item 4 above, Figures 13 and 14 are graphs showing similar temperature characteristics of the conventional device, and Figure 15 shows an example of the mover. It is a front view. DESCRIPTION OF SYMBOLS 1... Vibrator, 2... Base, 3a, 3b... Drive leg, 4... Mover, 5a, 5b... Lead wire, 6...
... Running surface, 11... Select switch, 13...
Frequency selection circuit, 15... High frequency oscillator, 17...
Power amplifier, 19... D/A converter, 21... Thermocouple, 25... Thermocouple amplifier, 29... Voltage generator,
31... Changeover switch, 35... DC bias generator, 37... Addition 2g, 40... CPU. Figure 1 Figure 2 Temperature Figure 3 Elapsed time 11J! (Minutes) Figure 4 Figure 5 Figure 6 Remaining = 50! (℃) Fig. 7 Fig. 8 □ Fig. 9 v Fig. 10 Fig. 11 Driving voltage (V) (a) Fig. 12 driving voltage (V) when low (b) Fig. 13 when high Distortion 150 TOO50050TOO150 Drive voltage (V
) (a) When low, Figure 14 Drive voltage (V) (b) When high

Claims (4)

[Claims] (1) a base made of an elastic body; a pair of drive legs that protrude vertically from both ends of the base and have mutually different resonance frequencies; A moving element is configured with a piezoelectric vibrator or an electrostrictive vibrator that excites the vibration of the drive foot of the drive foot, and by applying a predetermined frequency voltage to the piezoelectric vibrator or electrostrictive vibrator, the difference in resonance frequency can be adjusted. In a configuration including a drive circuit that moves the driving leg to the right or left based on the above, a frequency voltage that is different from the resonance frequency at which the drive leg moves to the right or left is applied to the drive circuit, and the piezoelectric vibrator Alternatively, a drive circuit for an ultrasonic linear motor, characterized in that it is equipped with a frequency voltage application circuit that stops the travel of the mover while the temperature of the electrostrictive vibrator is constantly raised to the saturation temperature. (2) a base made of an elastic body; a pair of drive legs that project vertically from both ends of the base and have mutually different resonance frequencies; and a pair of drive legs fixed to the base or between the pair of drive legs, A moving element is configured with a piezoelectric vibrator or an electrostrictive vibrator that excites the vibration of the drive foot of the drive foot, and by applying a predetermined frequency voltage to the piezoelectric vibrator or electrostrictive vibrator, the difference in resonance frequency can be adjusted. In a configuration including a drive circuit that moves the driving foot to the right or left based on the above, the piezoelectric vibrator or the electrostrictive vibrator is provided with means for detecting a temperature value of the vibrator when a frequency voltage is applied to the vibrator. , the drive circuit is characterized in that a frequency voltage selection circuit is attached to the drive circuit to select a frequency voltage matching a resonance frequency at which the drive foot moves to the right or to the left under this temperature condition based on the detected temperature value. Ultrasonic linear motor drive circuit. (3) A voltage generator is provided in the drive circuit to supply a positive voltage to increase the amount of residual displacement of the piezoelectric vibrator or electrostrictive vibrator when the application of the frequency voltage to the piezoelectric vibrator or electrostrictive vibrator is stopped. 3. The driving circuit for an ultrasonic linear motor according to claim 2, further comprising: a drive circuit for an ultrasonic linear motor. (4) A frequency voltage is applied to the drive circuit to maintain the amount of residual strain in the piezoelectric vibrator or electrostrictive vibrator at high temperatures by constantly applying a positive DC bias voltage to the piezoelectric vibrator or electrostrictive vibrator. Claims 1 and 2 characterized in that a circuit is attached.
Drive circuit for the ultrasonic linear motor described.