JP2000092869A - Driving circuit for ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving circuit for an ultrasonic motor having high reliability and capable of attaining optimum frequency of alternating current easily. SOLUTION: A CPU 8 closes the relay RL of a relay part 4, connects DC power supply 2 with two transformers T1, T2, and sets a gate IC in such a condition that a timing pulse signal from the CPU 8 can be conducted. The CPU 8 determines timing pulses P1, P2, P3, P4 for driving an ultrasonic motor 7 based on external information to output them to respective switching elements Q1, Q2, Q3, Q4. The respective switching elements Q1, Q2, Q3, Q4 passes the direct current of the DC power supply to the respective primary windings of the respective transformers T1, T2 with the timing pulses P1, P2, P3, P4. As a result, two levels of alternating currents Φ0, Φ90 of high frequency voltage occur with two phases having a phase difference 90 deg., which is applied to the ultrasonic motor 7 to drive it.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a driving circuit for an ultrasonic motor, and more particularly, to a driving circuit for an ultrasonic motor for producing a high-voltage alternating current necessary for operating a traveling ultrasonic motor. It belongs to the technical field.

2. Description of the Related Art Conventionally, various ultrasonic motors have been developed, and a progressive ultrasonic motor, which is one of the ultrasonic motors, operates according to the following principle. That is, on the surface of the elastic body that is the stator,
When the longitudinal wave and the transverse wave are combined to form a traveling wave that propagates at the speed of sound in the longitudinal direction of the elastic body, the traveling wave causes the surface of the elastic body to perform elliptical vibration. When the rotor is brought into pressure contact with the surface of the elastic body that is performing such elliptical vibration, the rotor comes into contact with the apex of the elastic body due to the elliptical vibration, and the vibration speed is increased due to the friction between the rotor and the stator. Then, it moves in the opposite direction to the traveling wave. In order to form a traveling wave on an elastic body which is a stator of such a traveling ultrasonic motor, a bending elastic wave is used. A method for generating this bending elastic wave will be described. As shown in FIG. 12A, a stator a is configured by attaching a piezoelectric body (piezoelectric ceramic) b in which adjacent sections are alternately polarized in the thickness direction to an elastic body c. In the figure, the arrow of the piezoelectric body b indicates the polarization direction. When a high-frequency voltage is applied to the piezoelectric ceramic b and the applied frequency is equal to the natural frequency of the stator a, the stator a resonates and causes bending vibration in the circumferential direction as shown in FIG. The vibration wave of the stator a is, for example, shown in FIG.
If it is divided into 9 wavelengths like this, 9 wave peaks m _{1 to} m ₉
Is formed, and this wave is a so-called standing wave. On the other hand, as shown in FIGS. 12 and 14, the phases of the mutual positions of the sections A and B of the piezoelectric ceramic 2 are shifted by ／ wavelength (λ) of the applied high-frequency voltage, and the sections A and B are mutually shifted. 90 ° time phase different by applying a high frequency voltage .PHI ₀ and .PHI _90, each of the high-frequency voltage .PHI ₀ as described above, the standing wave is generated by .PHI _90, the interference of these standing waves are mutually The traveling wave is formed only for the first time by being combined.

By the way, as the electric power required for the operation of the ultrasonic motor, as described above, the alternating current of the high-frequency voltages Ф ₀ and Ф ₉₀ whose time phases are different from each other by 90 ° is required. To increase the efficiency of the ultrasonic motor, it is necessary to maintain the alternating current at an optimum frequency. In addition, the drive circuit of the ultrasonic motor is required to improve its reliability. In addition, a drive circuit for the ultrasonic motor is required to easily generate such an alternating current. The present invention has been made in view of such a problem, and an object of the present invention is to provide a drive circuit for an ultrasonic motor that is highly reliable and can easily generate an AC having an optimum frequency. .

In order to solve the above-mentioned problems, a driving circuit for an ultrasonic motor according to the first aspect of the present invention comprises an ultrasonic motor for generating a high voltage alternating current necessary for operating the ultrasonic motor. In a motor drive circuit, a DC power supply, a transformer for applying an AC ultrasonic motor of a two-phase high-frequency voltage having a predetermined phase difference for driving the ultrasonic motor, and a DC current from the DC power supply to the transformer. And a central processing unit that controls the operation of the switching means at the predetermined timing. The invention according to claim 2 is provided with a temperature detecting means for monitoring a temperature rise of the switching means, and the central processing unit comprises:
When the temperature of the switching means detected by the temperature detecting means is equal to or higher than a first fixed temperature, the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced. Further, the invention according to claim 3 is provided with a temperature detecting means for monitoring a temperature rise of the switching means, and the central processing unit determines that the temperature of the switching means detected by the temperature detecting means is a first setting. When the temperature is equal to or higher than the temperature, the driving of the ultrasonic motor is stopped, or the output of the ultrasonic motor is set to the first level.
And when the temperature falls below a second set temperature lower than the first set temperature, the ultrasonic motor is re-driven at a first set output or higher. Further, the invention according to claim 4 is provided with a temperature detecting means for monitoring a rise in the temperature of the transformer, and the central processing unit determines that the temperature of the transformer detected by the temperature detecting means is a second constant temperature. In the above, the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced. Further, the invention according to claim 5 is provided with a temperature detecting means for monitoring a rise in the temperature of the transformer, and the central processing unit detects that the temperature of the transformer detected by the temperature detecting means is equal to or higher than a third set temperature. At the time of, the drive of the ultrasonic motor is stopped, or the output of the ultrasonic motor is reduced below a second predetermined output, and when the temperature falls below a fourth set temperature lower than the third set temperature, It is characterized in that the ultrasonic motor is driven again at a second predetermined output or more. Further, according to the invention of claim 6, when the information signal of the rotation state of the ultrasonic motor is supplied to the central processing unit, when the central processing unit detects abnormality of the ultrasonic motor based on the information signal, The driving of the ultrasonic motor is stopped. Further, the invention according to claim 7 is a drive circuit for an ultrasonic motor for producing a high voltage alternating current necessary for operating the ultrasonic motor, wherein a direct current power source and a direct current from the direct current power source are generated by a + potential and a − potential. DC high voltage converting means for converting to DC high voltage, and +
It is characterized by comprising switching means operating to supply a high DC voltage generated by the potential and the negative potential to the ultrasonic motor at a predetermined timing, and a central processing unit controlling the operation of the switching means at the predetermined timing. Further, the invention according to claim 8 is characterized by further comprising a sine wave converting means for converting the output from the switching means into a sine wave and supplying the sine wave to the ultrasonic motor. Further, the invention of claim 9 is characterized in that the central processing unit sets the operation timing of the switching means based on external information of the ultrasonic motor. Furthermore,
The invention according to claim 10 is characterized in that the central processing unit sets the operation timing of the switching means based on the rotation state of the ultrasonic motor.

In the ultrasonic motor driving circuit according to the present invention having the above-described structure, an alternating current for driving the ultrasonic motor from a direct current can be easily produced. Moreover,
By considering the external information and feeding back the rotational state of the ultrasonic motor, the alternating current applied to the ultrasonic motor is maintained at an optimal frequency, and the efficiency of the ultrasonic motor is increased. Further, the ultrasonic motor drive circuit according to the present invention has a self-diagnosis function of monitoring the temperature rise of the switching means, the temperature rise of the transformer, and the abnormality of the rotational state of the ultrasonic motor. Thereby, the reliability of the drive circuit of the ultrasonic motor is improved.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of an embodiment of a drive circuit for an ultrasonic motor according to the present invention.
Is an electric circuit diagram of this example. In the drive circuit of the ultrasonic motor of this example, an alternating current of two-phase high-frequency voltage having a phase difference of 90 ° or −90 ° is generated from a low-voltage direct current. A drive circuit for this will be described. FIG.
As shown in FIG. 1, a drive circuit 1 for the ultrasonic motor includes a DC power supply (DC power supply) 2 for generating a low-voltage DC, a noise filter 3, and a relay unit for supplying and cutting off DC from the DC power supply 2. 4, a switching element unit 5 for controlling the supply of DC from the DC power supply 2 with a predetermined timing pulse
And a DC section controlled by the switching element section 5 to generate a high-frequency voltage AC that has been boosted to a high voltage in two phases with a phase difference of 90 °, and supplies the AC to the ultrasonic motor 7. And a signal based on external information such as the load of the ultrasonic motor 7, a monitoring signal for monitoring the state of the power supply voltage of the DC power supply 2, the switching element unit 5 and the ultrasonic motor 7
Based on each feedback signal from the
And a central processing unit (CPU) 8 for controlling the relay unit 4 and the switching element unit 5 so that the frequency of the AC generated by the switching unit becomes optimum. With reference to the electric circuit diagram shown in FIG. 2, a description will be given of a method in which the ultrasonic motor drive circuit 1 generates a two-phase high-frequency voltage AC having a phase difference of 90 ° from a low-voltage DC. First, the CPU 8 outputs the control signal α to the relay unit 4 and closes the relay RL of the relay unit 4. Then, the DC power from the DC power source 2 becomes 2
The transformers T ₁ and T ₂ are supplied to the center of the primary winding.
Further, the CPU 8 sets the gate IC to a state where the timing pulse signal from the CPU 8 can be conducted by giving the gate signal β to the gate IC. Furthermore, CPU 8 is in the switching element 5, which is connected to both ends of the two primary windings of the switching elements Q _1, Q ₂ and the transformer T ₂ which is connected to both ends of the primary winding of the transformer T ₁ 2 number of switching elements Q _3, signals detected temperature information of the thermistor N ₁ attached to the heat radiating fins (not shown) of the Q ₄ gamma, signal monitoring information of the power supply voltage [delta], and on the basis of external information, as shown in FIG. 3 Ultrasonic motor 7
Timing pulse P ₁ is a 4-layer clock pulse for driving the, P _2, P _3, with determining the P _4, these timing pulses P _1, P _2, P _3, each switching element P ₄ respectively Q ₁ , Q ₂ , Q ₃ and Q ₄ are output. The timing pulses P ₁ , P ₂ , P ₃ and P ₄ shown in FIG. 3 are P ₁ → P ₃ → P ₂ →
It is output in the order of P ₄ → P ₁ . As a result, each switching element Q ₁ , Q ₂ , Q ₃ , Q ₄ causes the DC current of the DC power supply to pass through each transformer T ₁ , T ₂ according to these timing pulses P ₁ , P ₂ , P ₃ , P _4. In each of the primary windings. Therefore, the AC .PHI ₀ of boosted high-frequency voltage is generated in the secondary winding side of the transformer T _1, AC .PHI ₉₀ of the high-frequency voltage boosted in the secondary winding side of the transformer T ₂ occurs I do. At this time, the phase difference between the two alternating currents Ф ₀ and Ф ₉₀ generated is 90 に よ り due to the timing pulses P ₁ , P ₂ , P ₃ and P ₄ shown in FIG. In this manner, an alternating current of two-phase high-frequency voltage having a phase difference of 90 ° from the direct current is generated. When the two-phase alternating current is applied to the ultrasonic motor 7, the ultrasonic motor 7 operates. At this time, the information signal ε of the rotation state (number of rotations) is fed back to the CPU 8. Then, the CPU 8 obtains an optimum AC waveform for driving the ultrasonic motor 7 based on the external information and the rotation state of the ultrasonic motor 7, and sets the timing pulses P ₁ , P _2, P _3, P ₄
Is set. As described above, according to the drive circuit 1 of this example, the alternating current applied to the ultrasonic motor 7 can be maintained at the optimum frequency, so that the efficiency of the ultrasonic motor can be increased. In addition, according to the drive circuit 1, an alternating current can be easily generated by a direct current. By the way, when the ultrasonic motor 7 is operated by the alternating current generated from the direct current as described above, a sine wave is supplied to the ultrasonic motor 7, so that the capacitor component of the ultrasonic motor 7 and the transformers T ₁ and T ₂ are different. The parallel resonance occurs due to the inductance component on the secondary side,
When the ultrasonic motor 7 is driven for a long time, a large amount of power supply current flows through the switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ due to the change in the resonance frequency of the parallel resonance, and the switching elements Q ₁ , Q ₂ , Q ₃ and Q ₄ generate heat. Therefore, the heat generation of the switching elements _{Q 1, Q 2, Q 3} , Q 4 and monitored by thermistor N _1, when the temperature detected by the thermistor N ₁ is equal to or greater than a predetermined temperature, CPU 8 is a timing pulse P _1,
The output of P ₂ , P ₃ , and P ₄ is stopped, and the output of the gate signal of the gate IC is also stopped. As a result, the driving of the ultrasonic motor 7 stops. As described above, by stopping the ultrasonic motor by the double stop method, the ultrasonic motor 7 is reliably stopped when the switching elements Q ₁ , Q ₂ , Q ₃ , and Q ₄ are heated to a high temperature. I have. When the temperature detected by the thermistor N ₁ is equal to or higher than a predetermined temperature, the current applied to the ultrasonic motor 7 may be reduced by the transformers T ₁ and T ₂ . Further, to set the two comparison reference temperatures of the first set temperature lower than the first set temperature second set temperature, as shown in FIG. 4, the temperature detected by the thermistor N ₁ is first set temperature or more and When this happens, the driving of the ultrasonic motor 7 is stopped, or the output of the ultrasonic motor 7 is reduced below a predetermined output,
When the temperature detected by the thermistor N ₁ becomes equal to or lower than the second set temperature, the ultrasonic motor 7 is driven again at a predetermined output or higher, so that the drive control of the ultrasonic motor 7 may have hysteresis. . Further, the ultrasonic motor 7
Is fed back to the CPU 8 so that the CPU 8 stops the ultrasonic motor 7 by the above-described double stop method even when the CPU 8 detects an abnormality in the rotational state of the ultrasonic motor 7. . As described above, the drive circuit 1 of the ultrasonic motor 7 of this example has the self-diagnosis function, and when the temperature is abnormally increased and the rotational state is abnormal, the ultrasonic motor 7 is reliably stopped by the double stop method. Therefore, the reliability of the drive circuit 1 is improved.
FIG. 5 is an electric circuit diagram similar to FIG. 2, showing another example of the embodiment of the present invention. Note that the same components as those of the above-described drive circuit are denoted by the same reference numerals, and a detailed description thereof will be omitted. As described above, when the ultrasonic motor 7 is driven, parallel resonance occurs. However, if the resonance state of the parallel resonance is broken or if the ultrasonic motor 7 is driven for a long time, the windings of the transformers T ₁ and T ₂ are increased. The wires also generate heat due to copper loss. Therefore, the driving circuit 1 of this embodiment, in addition to the driving circuit 1 of the example described above, as shown in FIG. 5, further heating of the transformer T _1, T ₂ and monitored with a thermistor N _2, a thermistor N ₂ Signal ζ of the detected temperature information is input to CPU 8. When the temperatures of the transformers T ₁ and T ₂ are equal to or higher than a certain temperature, the CPU 8 issues timing pulses P ₁ and P 2
_2, P _3, and stops the output of the P ₄ stops driving the ultrasonic motor 7, or the transformer T _1, T ₂ by the output of the ultrasonic motor 7 decreases the current applied to the ultrasonic motor 7 Is made lower than a predetermined output. In this case, the thermistor N ₂ is provided in the primary winding portion that generates a large amount of heat as shown in FIG. Timing pulse P ₁ , P
₂ , P ₃ , P ₄ output stops, switching elements Q ₁ ,
Since Q ₂ , Q ₃ , and Q ₄ do not operate, current flows through the transformers T ₁ , T ₂
, And the operation of the transformers T ₁ and T ₂ stops. Thereby, the transformers T ₁ and T ₂ are protected. Moreover, by reducing the current applied to the ultrasonic motor 7, the output of the transformer T _1, T ₂ is reduced, suppressed heat generation of the transformer T _1, T ₂ is likewise transformer T _1, T ₂ is Protected. As described above, the drive circuit 1 of the ultrasonic motor 7 in this example further operates when the transformers T ₁ and T ₂ are abnormally heated.
The operation of the transformers T ₁ and T ₂ is stopped or the transformers T ₁ and T ₂
Or the heat generation of the transformers T ₁ and T ₂ is suppressed, so that the reliability of the drive circuit 1 is further improved. Note that the drive control of the ultrasonic motor 7 can be provided with hysteresis even when the transformers T ₁ and T ₂ are abnormally heated, as in the case shown in FIG. Other configurations and other effects of the drive circuit of the ultrasonic motor of this example are the same as those of the above-described example. FIG. 7 is a block diagram showing still another example of the embodiment of the present invention.
Fig. 8 is an electric circuit diagram of the example shown in Fig. 7. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted. In each of the above-described examples, the alternating current Ф ₀ and Ф ₉₀ are generated by flowing the direct current to the transformers T ₁ and T ₂ while performing switching control by the switching element unit 5. The drive circuit 1 converts the DC from the DC power supply into a DC high voltage by + potential and −potential, and switches the DC high voltage by a timing pulse while controlling the ultrasonic motor 7.
To supply it. In this case, the output waveform of the DC high voltage resulting from the switching is a square wave, and is converted into a sine wave and supplied to the ultrasonic motor 7. More specifically, as shown in FIG. 7, a drive circuit 1 for an ultrasonic motor according to this embodiment includes a DC power supply 2 and a DC from the DC power supply.
DC- for converting to DC high voltage by + potential and -potential
A DC converter 9, a switching element unit 5 that outputs these DC high voltages to the ultrasonic motor 7 while switching them, a CPU 8 that outputs a timing pulse to control the operation of the switching element unit 5, and a switching element unit 5.
And a resonance inductance 10 for converting the output square wave into a sine wave. With reference to the electric circuit diagram shown in FIG. 8, a description will be given of a method in which the ultrasonic motor drive circuit 1 of this example generates two-phase high-frequency AC having a phase difference of 90 ° from low-voltage DC. First, when a low-voltage direct current is supplied from the DC power supply 2 to the DC-DC converter 9, the DC-DC converter 9 converts the supplied direct current into a high direct-current voltage by a + potential and a − potential, and outputs the high voltage. . In that case, among these DC high voltage with a DC high voltage by one positive potential is supplied to the high-pressure switching element to Q ₁ switching element portion 5, the other - DC high voltage due to the potential of the switching element portion 5 It is supplied to the high-pressure switching element Q _2. Then, the CPU 8 outputs predetermined timing pulses P ₁ , P ₂ , P ₃ , P ₄ to the switching element section 5 and outputs the respective high-voltage switching elements Q ₁ , Q ₂ to these timing pulses P ₁ , P ₂ , P 4. _3, the switching control in accordance with P _4. These timing pulses P ₁ , P ₂ , P
_3, P ₄ can can either be configured in the same way as the previous example, to set the appropriate optionally outside. Thus, the high-frequency voltage .PHI ₀ from the high pressure switching element Q ₁ is outputted from the high-pressure switching element Q _2, a high frequency voltage .PHI ₀ temporal phase difference of 90 ° RF voltage .PHI ₉₀
Is output. At this time, each high-voltage switching element Q ₁ ,
Since the high-frequency voltages Ф ₀ and か ら₉₀ from Q ₂ are square waves and cannot drive the ultrasonic motor 7 smoothly, these square waves are converted into sine waves by the resonance inductance 10. It is supplied to the ultrasonic motor 7.
Thus, the ultrasonic motor 7 is driven smoothly. Other functions and effects of the ultrasonic motor drive circuit 1 of this example are the same as those of the above-described examples. FIG. 9 is an electric circuit diagram similar to FIG. 5, showing still another example of the embodiment of the present invention. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted. In the example shown in FIG. 5 described above, four switching elements Q ₁ , Q ₂ , Q ₃ , and Q ₄ are used in the switching element section 5, and each switching element Q ₁ , Q ₂ , Q ₃ , and Q _{4 is used} . The primary coil of each of the transformers T ₁ and T ₂ in the transformer section 6 is provided, and the CPU 8 outputs a four-phase clock pulse composed of four timing pulses P ₁ , P ₂ , P ₃ and P _4. However, in the example shown in FIG. 9, two switching elements Q ₂ , Q
₄ is omitted, the remaining two switching elements Q ₁ and Q ₃ are used, and primary coils of transformers T ₁ and T ₂ are provided for both switching elements Q ₁ and Q ₃ , respectively. As shown in FIG. 10 (a), as shown in FIG.
Switching elements Q ₁ , Q ₃
The CPU 8 outputs a two-phase clock pulse composed of two timing pulses P ₁ and P _{3 with} respect to. By one of the timing pulses P _1, the output of the switching element Q ₁ is, the output of only the upper portion of a sine wave as shown in Figure 10 (b). Similarly, the other of the timing pulses P _3, the output of the switching element Q ₃ are the output of only the upper portion of a sine wave as shown in Figure 10 (b). The outputs of these switching elements Q ₁ and Q ₃ are shifted from each other by １ ／ wavelength (λ), that is, 90 °. The other configuration of the drive circuit of the ultrasonic motor of this example is the same as the example shown in FIG. In the driving circuit 1 of the ultrasonic motor of this example is configured, the output of the switching element Q _1, transformer T ₁ is outputted to boosts the output of the switching element Q _1. At this time, the lower portion of the sine wave as the output of the switching element Q ₁ is shown in FIG. 10 (b) (- side portion) is missing, but does not output the switching element Q ₁ is in this part, the transformer T ₁ The secondary flyback effect, the secondary inductance L of the transformer T ₁ and the capacitance C of the ultrasonic motor 7
The resonance effect of the load based on, at the output and not part of the switching element Q ₁ as shown in FIG. 10 (c), the lower portion of the sine wave - so to output the (side portions). After all, the high-frequency voltage .PHI ₀ supplied from the transformer T ₁ to the ultrasonic motor 1 becomes full sinusoidal waveform. Similarly, the high-frequency voltage Ф ₉₀ supplied from the transformer T ₂ to the ultrasonic motor 1 also has a full sine wave waveform.
The high frequency voltage .PHI ₉₀ for the high-frequency voltage .PHI _0, becomes phase-quarter wavelength (lambda) i.e. 90 DEG. According to the drive circuit 1 of the ultrasonic motor 7 of this example, the number of switching elements can be reduced by two compared with the example shown in FIG. 5 and the number of parts can be reduced. Becomes easier. In addition, since the timing pulse output from the CPU 8 is reduced by two to become a two-phase clock pulse, the control is facilitated, the program processing is simplified, and the level of the CPU 8 can be lowered. Thus, the cost of the drive circuit 1 can be reduced, and the size of the substrate in the CPU 8 can be reduced. Other functions and effects of the drive circuit of the ultrasonic motor of this example are the same as those of the example shown in FIG. FIG. 11 is an electric circuit diagram similar to FIG. 8, showing still another example of the embodiment of the present invention. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted. In the example shown in FIG. 8 described above, the two high-voltage switching elements Q ₁ ; Q ₂ of the switching element section 5 are respectively supplied with two timing pulses P ₁ ,
P ₂ ; P ₃ , P ₄ are controlled. In the drive circuit 1 of this example, as shown in FIG. 11, each high-voltage switching element Q ₁ , Q ₂ is controlled by one timing pulse P _1. ,
So as to control at P _3. The timing pulses P ₁ and P _{3 at} this time are the same as those in FIG. The other configuration of the ultrasonic motor drive circuit of this example is the same as the example shown in FIG. Then, the high-frequency voltage Ф ₀ output from the high-voltage switching element Q ₁ and the high-voltage switching element Q ₂
The output of which is from the high-frequency voltage .PHI ₉₀ includes a fly-back effect of the resonant inductance 10, is converted to a full sine wave by the resonance effect due to the load based on the capacitance C of the resonant inductance 10 and the ultrasonic motor 7 It is supplied to the ultrasonic motor 7. Thus, the ultrasonic motor 7 is driven smoothly. Drive circuit 1 for ultrasonic motor 7 of this example
According to the embodiment, the timing pulse output from the CPU 8 is reduced by two to become a two-phase clock pulse as compared with the example shown in FIG. Can be lowered. Thus, the cost of the drive circuit 1 can be reduced, and the size of the substrate in the CPU 8 can be reduced. Other functions and effects of the driving circuit 1 of the ultrasonic motor of this example are the same as those of the example shown in FIG.

As is apparent from the above description, according to the ultrasonic motor drive circuit of the present invention, it is possible to easily produce an alternating current for driving the ultrasonic motor from a direct current. Further, by considering the external information and feeding back the rotational state of the ultrasonic motor, the alternating current applied to the ultrasonic motor can be maintained at an optimal frequency, and the efficiency of the ultrasonic motor can be improved. Furthermore, according to the ultrasonic motor drive circuit of the present invention, the self-diagnosis function of monitoring the temperature rise of the switching means, the temperature rise of the transformer, and the abnormality of the rotational state of the ultrasonic motor is provided. The reliability of the driving circuit is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an embodiment of a drive circuit for an ultrasonic motor according to the present invention.

FIG. 2 is an electric circuit diagram of the example shown in FIG.

FIG. 3 is a diagram showing a timing pulse of the example shown in FIGS. 1 and 5;

FIG. 4 is a diagram for explaining another example of drive control of the ultrasonic motor based on the temperature information in the examples shown in FIGS. 1 and 5;

FIG. 5 is an electric circuit diagram similar to FIG. 2, showing another example of the embodiment of the present invention.

FIG. 6 is a view showing a mounting position of a thermistor.

FIG. 7 is a block diagram showing still another example of the embodiment of the present invention.

8 is an electric circuit diagram of the example shown in FIG.

FIG. 9 is an electric circuit diagram similar to FIG. 5, showing still another example of the embodiment of the present invention.

10 shows signals in the electric circuit of the example shown in FIG. 9, (a) shows a timing pulse, (b) shows an output waveform of each of the switching elements Q ₁ and Q _{2 in} the switching element section, (C) is a diagram showing waveforms (output waveforms of a transformer) of the high-frequency voltages Ф ₀ and Ф ₉₀ applied to the ultrasonic motor.

FIG. 11 is an electric circuit diagram similar to FIG. 8, showing still another example of the embodiment of the present invention.

FIG. 12 shows a stator of a general ultrasonic motor,
(A) is a side view, (b) is a plan view.

FIG. 13 is a perspective view showing an excited state of a stator.

FIG. 14 is a diagram illustrating a method of exciting a stator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic motor drive circuit, 2 ... DC power supply (DC power supply), 4 ... Relay part, 5 ... Switching element part, 6 ... Transformer, 7 ... Ultrasonic motor, 8 ... Central processing unit (CP)
U), 9 ... DC-DC converter, 10 ... resonant inductance, RL ... relay, IC ... _{gate, Q 1, Q 2, Q} 3,
Q ₄ ... switching elements, T _1, T ₂ ... transformer, N _1, N ₂
… Thermistor, P ₁ , P ₂ , P ₃ , P ₄ … Timing pulse,
Ф ₀ , Ф ₉₀ … High frequency voltage

[Procedure amendment]

[Submission date] July 19, 1999 (1999.7.1)
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Detailed description of the invention

[Correction method] Change

[Correction contents]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a driving circuit for an ultrasonic motor, and more particularly, to a driving circuit for an ultrasonic motor for producing a high-voltage alternating current necessary for operating a traveling ultrasonic motor. It belongs to the technical field.

[0002]

2. Description of the Related Art Conventionally, various ultrasonic motors have been developed, and a progressive ultrasonic motor, which is one of the ultrasonic motors, operates according to the following principle. That is, on the surface of the elastic body that is the stator,
When the longitudinal wave and the transverse wave are combined to form a traveling wave that propagates at the speed of sound in the longitudinal direction of the elastic body, the traveling wave causes the surface of the elastic body to perform elliptical vibration. When the rotor is brought into pressure contact with the surface of the elastic body that is performing such elliptical vibration, the rotor comes into contact with the apex of the elastic body due to the elliptical vibration, and the vibration speed is increased due to the friction between the rotor and the stator. Then, it moves in the opposite direction to the traveling wave.

In order to form a traveling wave on an elastic body which is a stator of such a traveling ultrasonic motor, a bending elastic wave is used. A method for generating this bending elastic wave will be described. As shown in FIG. 12A, a stator a is configured by attaching a piezoelectric body (piezoelectric ceramic) b in which adjacent sections are alternately polarized in the thickness direction to an elastic body c. In the figure, the arrow of the piezoelectric body b indicates the polarization direction.

When a high-frequency voltage is applied to the piezoelectric ceramic b and the applied frequency is equal to the natural frequency of the stator a, the stator a resonates and causes bending vibration in the circumferential direction as shown in FIG. If the vibration wave of the stator a is divided into nine wavelengths in the circumferential direction as shown in FIG. 13, for example, nine wave peaks m _{1 to} m ₉ are formed, and this wave is a so-called standing wave. It is called a wave.

On the other hand, as shown in FIGS.
Piezoelectric shifted 3/4 wavelength of the applied high frequency voltage phase of the mutual position between the ceramics 2 Category A Category B (lambda), and Category A Category B mutual temporal phases 90 ° different high frequency voltage Ф ₀ and the application of a .PHI _90, each of the high-frequency voltage .PHI ₀ as described above, the standing wave is generated by .PHI _90, by these standing waves are synthesized cause interference with each other, the first traveling wave Is formed.

[0006]

By the way, as the electric power required for the operation of the ultrasonic motor, as described above, the alternating current of the high-frequency voltages Ф ₀ and Ф ₉₀ whose time phases are different from each other by 90 ° is required. To increase the efficiency of the ultrasonic motor, it is necessary to maintain the alternating current at an optimum frequency. In addition, the drive circuit of the ultrasonic motor is required to improve its reliability. In addition, a drive circuit for the ultrasonic motor is required to easily generate such an alternating current.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a drive circuit for an ultrasonic motor which has high reliability and can easily produce an AC having an optimum frequency. That is.

[0008]

In order to solve the above-mentioned problems, a driving circuit for an ultrasonic motor according to the first aspect of the present invention comprises an ultrasonic motor for generating a high voltage alternating current necessary for operating the ultrasonic motor. In a motor drive circuit, a DC power supply, a transformer for applying an AC ultrasonic motor of a two-phase high-frequency voltage having a predetermined phase difference for driving the ultrasonic motor, and a DC current from the DC power supply to the transformer. And a central processing unit that controls the operation of the switching means at the predetermined timing.

Further, the invention of claim 2 is provided with a temperature detecting means for monitoring a rise in temperature of the switching means, and the central processing unit detects the temperature of the switching means detected by the temperature detecting means. When the temperature is equal to or higher than the first predetermined temperature, the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced.

Further, according to a third aspect of the present invention, there is provided a temperature detecting means for monitoring a rise in the temperature of the switching means, and the central processing unit is adapted to detect the temperature of the switching means detected by the temperature detecting means. When the temperature is equal to or higher than the first set temperature, the driving of the ultrasonic motor is stopped, or the output of the ultrasonic motor is reduced below a first predetermined output, and is set to be equal to or lower than a second set temperature lower than the first set temperature. When this happens, the ultrasonic motor is re-driven at a first predetermined output or more.

Further, according to a fourth aspect of the present invention, there is provided a temperature detecting means for monitoring a rise in temperature of the transformer, and the central processing unit causes the temperature of the transformer detected by the temperature detecting means to be a second temperature. When the temperature is equal to or higher than the predetermined temperature, the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced.

Further, according to a fifth aspect of the present invention, there is provided a temperature detecting means for monitoring a rise in the temperature of the transformer, and the central processing unit detects the temperature of the transformer detected by the temperature detecting means as a third temperature. When the temperature is equal to or higher than the set temperature, the driving of the ultrasonic motor is stopped, or the output of the ultrasonic motor is reduced below a second predetermined output, and becomes equal to or lower than a fourth set temperature lower than the third set temperature. At this time, the ultrasonic motor is re-driven at a second output or more.

Further, according to a sixth aspect of the present invention, an information signal of a rotation state of the ultrasonic motor is supplied to the central processing unit, and the central processing unit detects abnormality of the ultrasonic motor based on the information signal. Then, the driving of the ultrasonic motor is stopped.

According to a seventh aspect of the present invention, there is provided an ultrasonic motor driving circuit for generating a high voltage alternating current necessary for operating the ultrasonic motor, wherein a direct current power source and a direct current from the direct current power source are supplied with a + potential and DC high voltage converting means for converting into a DC high voltage by a -potential, and switching means operating to flow a DC high voltage from the DC high voltage converting means by a + potential and a-potential to an ultrasonic motor at a predetermined timing. And a central processing unit for controlling the operation of the switching means at the predetermined timing.

Further, the invention according to claim 8 is characterized by further comprising sine wave converting means for converting the output from the switching means into a sine wave and supplying the sine wave to the ultrasonic motor. Further, the invention of claim 9 is characterized in that the central processing unit sets the operation timing of the switching means based on external information of the ultrasonic motor. Further, in the invention according to claim 10, the central processing unit comprises:
The operation timing of the switching means is set based on the rotation state of the ultrasonic motor.

[0016]

In the ultrasonic motor driving circuit according to the present invention having the above-described structure, an alternating current for driving the ultrasonic motor from a direct current can be easily produced. Moreover,
By considering the external information and feeding back the rotational state of the ultrasonic motor, the alternating current applied to the ultrasonic motor is maintained at an optimal frequency, and the efficiency of the ultrasonic motor is increased. Further, the ultrasonic motor drive circuit according to the present invention has a self-diagnosis function of monitoring the temperature rise of the switching means, the temperature rise of the transformer, and the abnormality of the rotational state of the ultrasonic motor. Thereby, the reliability of the drive circuit of the ultrasonic motor is improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of an embodiment of a drive circuit for an ultrasonic motor according to the present invention.
Is an electric circuit diagram of this example. In the drive circuit of the ultrasonic motor of this example, an alternating current of two-phase high-frequency voltage having a phase difference of 90 ° or −90 ° is generated from a low-voltage direct current. A drive circuit for this will be described.

As shown in FIG. 1, a drive circuit 1 for this ultrasonic motor supplies a DC power supply (DC power supply) 2 for generating a low-voltage DC, a noise filter 3, and a DC power supply from the DC power supply 2. A relay unit 4 that performs cut-off control, a switching element unit 5 that controls the supply of DC from the DC power supply 2 with a predetermined timing pulse, and a DC that is controlled and supplied by the switching element unit 5 has a phase difference of 90 °. In two phases,
A transformer unit 6 that generates an alternating current of a high frequency voltage boosted to a high voltage and supplies it to the ultrasonic motor 7, a signal based on external information such as a load of the ultrasonic motor 7, and a monitor that monitors the state of the power supply voltage of the DC power supply 2. A central processing unit that controls the relay unit 4 and the switching element unit 5 based on the signals, the feedback signals from the switching element unit 5 and the ultrasonic motor 7 so that the AC frequency generated by the transformer unit 6 is optimized. CPU) 8.

Referring to the electric circuit diagram shown in FIG. 2, a method in which the ultrasonic motor drive circuit 1 generates a two-phase high-frequency voltage alternating current having a phase difference of 90 ° from a low-voltage direct current voltage will be described. First, the CPU 8 sends a control signal α to the relay section 4.
Is output to close the relay RL of the relay unit 4. Then
DC power is supplied from the DC power supply 2 to the center of the primary windings of the _two transformers T ₁ and T ₂ . Further, the CPU 8 sets the gate IC to a state where the timing pulse signal from the CPU 8 can be conducted by giving the gate signal β to the gate IC.

Furthermore, CPU 8 is in the switching element 5, respectively connected to both ends of the two primary windings of the switching elements Q _1, Q ₂ and the transformer T ₂ which is connected to both ends of the primary winding of the transformer T ₁ are two signals of the detection temperature information of the switching element Q _3, a thermistor N ₁ attached to the heat radiating fins (not shown) of Q ₄ and gamma, based on the signal [delta], and the external information monitoring information of the power supply voltage,
4 for driving the ultrasonic motor 7 as shown in FIG.
Timing pulses P ₁ , P ₂ , P
₃ , P ₄ , and these timing pulses P ₁ , P ₂ , P ₃ , P ₄ are respectively connected to the switching elements Q ₁ ,
Output to Q ₂ , Q ₃ , Q ₄ . The timing pulses P ₁ , P ₂ , P ₃ , and P ₄ shown in FIG. 3 are output in the order of P ₁ → P ₃ → P ₂ → P ₄ → P ₁ .

Thus, each of the switching elements Q ₁ , Q ₂ ,
Q ₃ and Q ₄ correspond to these timing pulses P ₁ , P ₂ , P ₃ and P ₄
, The DC current of the DC power supply is applied to each transformer T ₁ , T
₂ to each primary winding. Therefore, the AC .PHI ₀ of boosted high-frequency voltage is generated in the secondary winding side of the transformer T _1, AC .PHI ₉₀ of the high-frequency voltage boosted in the secondary winding side of the transformer T ₂ occurs I do. At this time, the phase difference between the two alternating currents Ф ₀ and Ф ₉₀ generated is 90 に よ り due to the timing pulses P ₁ , P ₂ , P ₃ and P ₄ shown in FIG. In this manner, an alternating current of two-phase high-frequency voltage having a phase difference of 90 ° from the direct current is generated. And this 2
When the phase alternating current is applied to the ultrasonic motor 7, the ultrasonic motor 7 operates. At this time, the information signal ε of the rotation state (number of rotations) is fed back to the CPU 8.
Then, the CPU 8 obtains an optimum AC waveform for driving the ultrasonic motor 7 based on the external information and the rotation state of the ultrasonic motor 7, and sets the timing pulses P ₁ , P ₂ , P ₃ and P ₄ are set.

As described above, according to the drive circuit 1 of this embodiment, the alternating current applied to the ultrasonic motor 7 can be maintained at the optimum frequency, so that the efficiency of the ultrasonic motor can be increased. it can. Moreover, this drive circuit 1
According to this, an alternating current can be easily produced by a direct current.

When the ultrasonic motor 7 is operated by the alternating current generated from the direct current as described above, a sine wave is supplied to the ultrasonic motor 7, so that the capacitor component of the ultrasonic motor 7 and the transformers T ₁ and T _{1 Due to} the secondary side inductance component of 2, parallel resonance occurs, but
When the ultrasonic motor 7 is driven for a long time, a large amount of power supply current flows through the switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ due to the change in the resonance frequency of the parallel resonance, and the switching elements Q ₁ , Q ₂ , Q ₃ and Q ₄ generate heat.

Therefore, the switching elements Q ₁ , Q ₂ , Q
_3, the heat generation of the Q ₄ is monitored by a thermistor N _1, thermistor N ₁
When the temperature detected in the step becomes a certain temperature or more, the CPU
8 stops the output of the timing pulses P ₁ , P ₂ , P ₃ , P ₄ and also stops the output of the gate signal of the gate IC. As a result, the driving of the ultrasonic motor 7 stops. As described above, by stopping the ultrasonic motor by the double stop method, the switching elements Q ₁ , Q ₂ , Q ₃ ,
At a high temperature heating of Q _4, and so as to stop the ultrasonic motor 7 reliably.

When the temperature detected by the thermistor N ₁ exceeds a certain temperature, the current applied to the ultrasonic motor 7 may be reduced by the transformers T ₁ and T ₂ . In addition, as shown in FIG.
Set the two comparison reference temperature lower than the set temperature the second set temperature, when the temperature detected by the thermistor N ₁ becomes the first preset temperature or more, or to stop the drive of the ultrasonic motor 7, or The output of the ultrasonic motor 7 is reduced below a predetermined output, and when the temperature detected by the thermistor N ₁ becomes lower than the second set temperature, the ultrasonic motor 7 is driven again at a predetermined output or higher, Sound wave motor 7
It is also possible to give hysteresis to the drive control. Further, by sending the information signal of the rotation state of the ultrasonic motor 7 to the CPU 8, even when the CPU 8 detects an abnormality in the rotation state of the ultrasonic motor 7, the ultrasonic motor 7 is stopped by the above-described double stop method. I try to stop.

As described above, the drive circuit 1 of the ultrasonic motor 7 of this embodiment has a self-diagnosis function, and when the temperature is abnormally increased and the rotational state is abnormal, the ultrasonic motor 7 is stopped by a double stop method. Since the stop is ensured, the drive circuit 1
Reliability is improved.

FIG. 5 is an electric circuit diagram similar to FIG. 2, showing another example of the embodiment of the present invention. Note that the same components as those of the above-described drive circuit are denoted by the same reference numerals, and a detailed description thereof will be omitted.

As described above, when the ultrasonic motor 7 is driven,
Parallel resonance is performed. If the resonance state of the parallel resonance is lost or the ultrasonic motor 7 is driven for a long time, the windings of the transformers T ₁ and T ₂ also generate heat due to copper loss. Therefore, in the drive circuit 1 of this example, in addition to the drive circuit 1 of the above-described example, as shown in FIG. 5, the heat generation of the transformers T ₁ and T ₂ is further monitored by the thermistor N ₂ , and the thermistor N ₂
The signal の of the temperature information detected in ₂ is input to the CPU 8. When the temperatures of the transformers T ₁ and T ₂ are equal to or higher than a certain temperature, the CPU 8 issues timing pulses P ₁ , P ₂ , P ₃ ,
Or to stop the output of the P ₄ stops driving the ultrasonic motor 7, or trans T _1, the T ₂ decreases the current applied to the ultrasonic motor 7 decreases below a predetermined outputs the output of the ultrasonic motor 7 I try to make it. In this case, the thermistor N ₂ is provided in the primary winding portion that generates a large amount of heat as shown in FIG.

When the output of the timing pulses P ₁ , P ₂ , P ₃ , P ₄ is stopped, the switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ do not operate, so that a current is applied to the transformers T ₁ , T _2. And the operation of the transformers T ₁ and T ₂ stops. This allows
Transformers T ₁ and T ₂ are protected. Also, the ultrasonic motor 7
The transformers T ₁ , T _1
Since the output of the transformer ₂ decreases, the heat generation of the transformers T ₁ and T ₂ is suppressed, and the transformers T ₁ and T ₂ are similarly protected.

[0030] Thus, the drive circuit 1 of the ultrasonic motor 7 in this example, further abnormal Atsushi Nobori of the transformer T _1, T _2, either stop the operation of the transformer T _1, T _2, the transformer T ₁ , and either output reduction of T _2, since the suppressing heat generation of the transformer T _1, T _2, the reliability of the drive circuit 1 becomes further improved. Note that the drive control of the ultrasonic motor 7 can be provided with hysteresis even when the transformers T ₁ and T ₂ are abnormally heated, as in the case shown in FIG. Other configurations and other effects of the drive circuit of the ultrasonic motor of this example are the same as those of the above-described example.

FIG. 7 is a block diagram showing still another embodiment of the present invention, and FIG. 8 is an electric circuit diagram of the embodiment shown in FIG. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted. In each of the above-described examples, the alternating current Ф ₀ and Ф ₉₀ are generated by flowing the direct current to the transformers T ₁ and T ₂ while performing switching control by the switching element unit 5. The drive circuit 1 converts a direct current from a direct current power supply into a high DC voltage by a + potential and a − potential, and supplies the DC high voltage to the ultrasonic motor 7 while switching the DC high voltage with a timing pulse. In this case, the output waveform of the DC high voltage resulting from the switching is a square wave, and is converted into a sine wave and supplied to the ultrasonic motor 7.

More specifically, as shown in FIG. 7, a drive circuit 1 for an ultrasonic motor according to this embodiment comprises a DC power supply 2
A DC-DC converter 9 for converting a DC from a DC power supply into a DC high voltage by a + potential and a − potential, and an ultrasonic motor 7 while switching these DC high voltages.
And a CPU for outputting a timing pulse and controlling the operation of the switching element 5
8 and a resonance inductance 10 for converting a square wave output from the switching element unit 5 into a sine wave.

Referring to the electric circuit diagram shown in FIG. 8, a method in which the drive circuit 1 of the ultrasonic motor of this embodiment generates a two-phase high-frequency voltage AC having a phase difference of 90 ° from a low-voltage DC. explain. First, when a low-voltage direct current is supplied from the DC power supply 2 to the DC-DC converter 9,
The -DC converter 9 converts the supplied direct current into a direct current high voltage by a + potential and a -potential and outputs it. In that case, among these DC high voltage with a DC high voltage by one positive potential is supplied to the high-pressure switching element to Q ₁ switching element portion 5, the other - DC high voltage due to the potential of the switching element portion 5 It is supplied to the high-pressure switching element Q _2.

Then, the CPU 8 outputs predetermined timing pulses P ₁ , P ₂ , P ₃ , P ₄ to the switching element section 5 and outputs the high-voltage switching elements Q ₁ , Q ₂ to these timing pulses P ₁ , P 2. Switching control is performed according to ₂ , P ₃ and P ₄ . These timing pulses P ₁ , P ₂ , P ₃ , and P ₄ can be set in the same manner as in the above-described example, or can be set arbitrarily outside. Thus, the high-frequency voltage .PHI ₀ from the high pressure switching element Q ₁ is outputted from the high-pressure switching element Q _2, the time phase with a high frequency voltage .PHI ₀ is output 90 ° different RF voltage .PHI _90.
At this time, the high frequency voltages Ф ₀ , Ф ₉₀ from the high voltage switching elements Q ₁ , Q ₂ are square waves and cannot drive the ultrasonic motor 7 smoothly. Is converted into a sine wave and supplied to the ultrasonic motor 7. Thus, the ultrasonic motor 7 is driven smoothly. Other functions and effects of the ultrasonic motor drive circuit 1 of this example are the same as those of the above-described examples.

FIG. 9 is an electric circuit diagram similar to FIG. 5, showing still another example of the embodiment of the present invention. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted. In the example shown in FIG. 5 described above, four switching elements Q ₁ , Q ₂ , Q ₃ , and Q ₄ are used in the switching element section 5, and each switching element Q ₁ , Q ₂ , Q ₃ , and Q _{4 is used} . , A primary coil of each transformer T ₁ , T ₂ in the transformer section 6, and four timing pulses P ₁ , P ₂ ,
Although a four-phase clock pulse composed of P ₃ and P ₄ is output, in the example shown in FIG. 9, two switching elements Q ₂ and Q ₄ are omitted in the switching element section 5 and the remaining elements are omitted. together and using two switching elements Q _1, Q _3, provided with a respective transformer T _1, the primary side coil of the T ₂ respectively both switching elements Q _1, Q _3, shown in FIG. 10 (a) As described above, of the four timing pulses shown in FIG. 3, a two-phase clock pulse composed of two timing pulses P ₁ and P ₃ for the switching elements Q ₁ and Q _{3 is} output from the CPU 8.

Then, one timing pulse P₁By
Switching element Q₁Is shown in FIG. 10 (b).
The output is only the upper part of such a sine wave. Similarly,
The other timing pulse P_ThreeBy switching element
Q_ThreeIs the upper side of the sine wave as shown in FIG.
Only the part is output. These switching elements Q₁,
Q _ThreeAre mutually 互 い に wavelength (λ), ie, 9
It is shifted by 0 °. The ultrasonic motor of this example
Other configurations of the drive circuit are the same as those in the example shown in FIG.

The ultrasonic mode thus constructed in this example is
In the driving circuit 1 of the switch, the switching element Q₁Out of
By force, transformer T₁Is the switching element Q₁Output
Increase the pressure and output. At this time, the switching element Q₁of
As shown in FIG. 10B, the output is the lower part of the sine wave (−
Side part) is missing, and the switching element Q ₁
Does not output, but the transformer T₁Secondary side flyback
Effect and transformer T₁The secondary inductance L and
Effect by the load based on the capacitance C of the ultrasonic motor 7
As a result, as shown in FIG.
Q₁The lower part of the sine wave (-side part)
Minutes). After all, transformer T₁From super
High frequency voltage supplied to the ultrasonic motor 1₀Is the full sine
It becomes a wave shape. Similarly, the transformer T_TwoFrom ultrasound
High frequency voltage supplied to motor 1₉₀Also full sine wave
A high-frequency voltage₉₀Is high frequency
Pressure₀Has a phase of １ ／ wavelength (λ), that is, 90
゜ It is shifted. Drive time of the ultrasonic motor 7 of this example
According to the path 1, the switching element is different from the example shown in FIG.
Reduces the number of parts by two, and
The internal circuit is reduced, making it easier to create a transformer.
You. In addition, the timing pulse output from the CPU 8 is also 2
Control pulse is reduced to a two-phase clock pulse.
And the program processing becomes simpler,
The level of U8 can be lowered. This drives
The cost of the circuit 1 can be reduced and the CP
The size of the substrate in U8 can be reduced.
You. Other effects of the ultrasonic motor drive circuit of this example
Is the same as the example shown in FIG.

FIG. 11 is an electric circuit diagram similar to FIG. 8, showing still another example of the embodiment of the present invention. Note that the same components as those of the drive circuit of each of the above-described examples are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In the example shown in FIG. 8, the two high-voltage switching elements Q _{1 and} Q ₂ of the switching element section 5 are controlled by two timing pulses P ₁ , P ₂ ; P ₃ and P _{4 respectively} . However, in the drive circuit 1 of this example, FIG.
As shown in FIG. 1, each of the high-voltage switching elements Q ₁ and Q ₂ is controlled by _one timing pulse P ₁ and P ₃ , respectively. The timing pulses P ₁ and P _{3 at} this time are the same as those in FIG. The other configuration of the drive circuit of the ultrasonic motor of this example is the same as the example shown in FIG.

[0040] Then, a high frequency voltage .PHI ₉₀ that is the output from the high-frequency voltage .PHI ₀ and the high-voltage switching element Q ₂ which is the output from the high-pressure switching element Q ₁ is a fly-back effect of the resonant inductance 10, resonant inductance The signal is converted into a full sine wave by the resonance effect of the load based on the capacitance C of the ultrasonic motor 7 and supplied to the ultrasonic motor 7. Thus, the ultrasonic motor 7 is driven smoothly.

According to the drive circuit 1 of the ultrasonic motor 7 of this embodiment, the timing pulse output from the CPU 8 is reduced by two to become a two-phase clock pulse as compared with the embodiment shown in FIG. At the same time, the program processing is simplified, and the level of the CPU 8 can be reduced. Thus, the cost of the drive circuit 1 can be reduced, and the size of the substrate in the CPU 8 can be reduced. Other operational effects of the ultrasonic motor drive circuit 1 of this example are the same as those of the example shown in FIG.

[0042]

As is apparent from the above description, according to the ultrasonic motor drive circuit of the present invention, it is possible to easily produce an alternating current for driving the ultrasonic motor from a direct current. Further, by considering the external information and feeding back the rotational state of the ultrasonic motor, the alternating current applied to the ultrasonic motor can be maintained at an optimal frequency, and the efficiency of the ultrasonic motor can be improved. Furthermore, according to the ultrasonic motor drive circuit of the present invention, the self-diagnosis function of monitoring the temperature rise of the switching means, the temperature rise of the transformer, and the abnormality of the rotational state of the ultrasonic motor is provided. The reliability of the driving circuit is improved.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Kitazawa 1-4-30 Roppongi, Minato-ku, Tokyo F-term (reference) 5H680 AA06 AA08 AA09 BB03 BB16 CC02 CC07 DD01 DD15 DD23 DD27 DD53 DD66 DD87 FF08 FF25 FF30 FF33 FF38 FF40

Claims (10)

[Claims] 1. An ultrasonic motor drive circuit for generating a high-voltage alternating current necessary for operating an ultrasonic motor, comprising: a DC power supply; and a two-phase high-frequency voltage having a predetermined phase difference for driving the ultrasonic motor. A transformer applied to the AC ultrasonic motor, switching means for operating the DC current from the DC power supply to the transformer at a predetermined timing, and a central processing unit for controlling the operation of the switching means at the predetermined timing. A driving circuit for an ultrasonic motor, comprising: 2. A temperature detecting means for monitoring a temperature rise of the switching means, wherein the central processing unit comprises:
When the temperature of the switching means detected by the temperature detecting means is equal to or higher than a first predetermined temperature, the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced. Item 2. A drive circuit for an ultrasonic motor according to Item 1. 3. A temperature detecting means for monitoring a temperature rise of the switching means, wherein the central processing unit comprises:
When the temperature of the switching means detected by the temperature detecting means is equal to or higher than a first set temperature, the drive of the ultrasonic motor is stopped, or the output of the ultrasonic motor is reduced from a first predetermined output, 2. The driving circuit for an ultrasonic motor according to claim 1, wherein the ultrasonic motor is re-driven at a first predetermined output or more when the temperature falls below a second set temperature lower than the first set temperature. 4. A temperature detecting means for monitoring a rise in temperature of the transformer, wherein the central processing unit detects a temperature of the transformer detected by the temperature detecting means as a second temperature.
4. The driving circuit for an ultrasonic motor according to claim 1, wherein the driving of the ultrasonic motor is stopped or the output of the ultrasonic motor is reduced when the temperature is equal to or higher than a predetermined temperature. . 5. A temperature detecting means for monitoring a rise in temperature of the transformer, wherein the central processing unit detects that the temperature of the transformer detected by the temperature detecting means is a third temperature.
When the temperature is equal to or higher than the set temperature, the driving of the ultrasonic motor is stopped, or the output of the ultrasonic motor is reduced below a second predetermined output, and becomes equal to or lower than a fourth set temperature lower than the third set temperature. 5. The ultrasonic motor driving circuit according to claim 1, wherein said ultrasonic motor is re-driven at a second output or more. 6. An information signal of a rotation state of the ultrasonic motor is supplied to the central processing unit. When the central processing unit detects abnormality of the ultrasonic motor based on the information signal, the ultrasonic motor 6. The driving circuit for an ultrasonic motor according to claim 1, wherein the driving of the ultrasonic motor is stopped. 7. A driving circuit for an ultrasonic motor for producing a high-voltage alternating current necessary for operating the ultrasonic motor, comprising: a DC power supply;
DC high voltage converting means for converting into a DC high voltage by a potential; switching means operable to flow a DC high voltage from the DC high voltage converting means by a + potential and a − potential to an ultrasonic motor at a predetermined timing; A driving circuit for an ultrasonic motor, comprising: a central processing unit for controlling the operation of the switching means at the predetermined timing. 8. A driving circuit for an ultrasonic motor according to claim 7, further comprising a sine wave converting means for converting an output from said switching means into a sine wave and supplying the sine wave to an ultrasonic motor. . 9. The ultrasonic motor drive circuit according to claim 1, wherein the central processing unit sets the operation timing of the switching means based on external information of the ultrasonic motor. . 10. The driving of the ultrasonic motor according to claim 1, wherein the central processing unit sets the operation timing of the switching means based on the rotation state of the ultrasonic motor. circuit.