JP2001211672A - Ultrasonic motor control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a device which can be driven independently or simultaneously, by using a plurality of ultrasonic motors. SOLUTION: A plurality of ultrasonic motor 2 and 3 which have respectively different mechanical resonance frequencies are branched from one output line 7 extended from a driver 1. A 1st driving frequency output circuit 1a and a 2nd drive frequency output circuit 1b, which output driving frequencies corresponding to the mechanical resonance frequencies of the respective ultrasonic motors, are provided in the driver. Further, respective driving frequency signals f1 and f2 are superposed upon each other by a mixer 4 and outputted from the driver. If only one drive frequency signal is outputted, only the corresponding ultrasonic motor is resonated and the other is not. With this constitution, only a single driver is necessary and wirings between the driver and the respective ultrasonic motors can be reduced as many as possible, so that weight reduction, dimensional reduction and cost reduction of a system as a whole can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor control circuit for driving a plurality of ultrasonic motors.

[0002]

2. Description of the Related Art An ultrasonic motor has a simple structure and can generate a large torque as compared with an electromagnetic motor, so that a motor requiring the same torque can be made compact. Suitable for use in such devices. In such an ultrasonic motor, a piezoelectric element is attached to a resonator made of an elastic body, and a comb is formed on a side opposite to the side on which the piezoelectric element is attached to form a stator, and the elastic support is provided. The rotator is resiliently urged against the comb teeth, and a high frequency voltage is applied to the piezoelectric element to generate a traveling wave or a standing wave on the comb teeth, which makes resilient contact with the comb teeth. There is one that rotates a rotor.

[0003]

The driving frequency of the ultrasonic motor having the above-mentioned structure is affected by various factors such as the shape and the pressing load of the rotor. Drivers capable of outputting a motor applied voltage corresponding to the drive frequency of each ultrasonic motor are required in a one-to-one relationship. Therefore, when two or more ultrasonic motors are separately driven, ultrasonic motors having different driving frequencies (mechanical resonance frequencies) are controlled by corresponding drivers.

Therefore, in the case of a device which can be driven independently or simultaneously by using a plurality of ultrasonic motors as described above, the number of drivers is required by the number of motors. However, since the cost occupied by the driver in the ultrasonic motor system is large, there is a problem that the cost increases in the case of a device using a plurality of ultrasonic motors and capable of independent control.

[0005]

An ultrasonic motor control circuit for driving a plurality of ultrasonic motors having different mechanical resonance frequencies from each other. Each drive frequency output means for outputting a drive frequency signal corresponding to each mechanical resonance frequency of the ultrasonic motor, and one drive frequency output means provided between each drive frequency output means and the plurality of ultrasonic motors An output line, the drive frequency signals from each of the drive frequency output means are collectively input to the output line, and the plurality of ultrasonic motors are connected in parallel to the output line, When driving the ultrasonic motors independently, the drive frequency signals are output to the output lines independently, and when the plurality of ultrasonic motors are simultaneously driven in any combination, It was assumed to be outputted to the output line by superimposing a corresponding one of the driving frequency signal.

According to this, when a plurality of ultrasonic motors are provided, the number of output lines leading to the ultrasonic motors can be reduced, and it is not necessary to provide the same number of output lines as the number of ultrasonic motors. The number of output lines can be reduced to one, so that wiring to the ultrasonic motor can be omitted as much as possible, and the effect of noise can be prevented by simplifying the wiring.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings.

FIG. 1 is a schematic block diagram of a control circuit for an ultrasonic motor to which the present invention is applied. As shown in FIG. 1, a plurality of (two in the illustrated example) ultrasonic motors 2 and 3 are branched and connected to one output line 7 from the driver 1. Each of the ultrasonic motors 2 and 3 has a different mechanical resonance frequency. For example, the mechanical resonance frequency of one ultrasonic motor 2 is 32 kHz and the mechanical resonance frequency of the other ultrasonic motor 3 is It is 52 kHz.

In the driver 1, as shown in FIG.
The mechanical resonance frequency of the one ultrasonic motor 2 (32 k
Hz) as the driving frequency output means for outputting the driving frequency (32 kHz) corresponding to the first driving frequency output circuit 1
a and a second drive frequency output circuit 1b as drive frequency output means for outputting a drive frequency (52 kHz) corresponding to the mechanical resonance frequency (52 kHz) of the other ultrasonic motor 3.

The respective driving frequency signals f1 and f2 output from the respective driving frequency output circuits 1a and 1b are the respective sine waves shown in FIG. 2 and further serve as superimposing means provided in the driver circuit 1. The output is superimposed and output collectively by the mixer 4. The mixer 4 is connected to one output terminal 6 provided on the driver 1, and the output terminal 6 is connected to an output line 7 for one ultrasonic motor. The ultrasonic motors 2 and 3 are connected to the respective branch lines so as to be parallel to each other.

When only one of the ultrasonic motors 2 and 3 is driven, only the selected one of the driving frequency signals f1 and f2 is output, and only the corresponding one of the ultrasonic motors 2 and 3 is output. Resonates. This is because the resonance part of each ultrasonic motor itself acts as a mechanical filter,
This is to select, resonate and drive its own mechanical resonance frequency. For example, when a drive frequency signal f1 of 32 kHz is output, one ultrasonic motor 2 resonates,
The other ultrasonic motor 3 whose mechanical resonance frequency is 52 kHz does not resonate, and when the drive frequency signal f2 of 52 kHz is output, the other ultrasonic motor 3 resonates and the mechanical resonance frequency is 32 kHz. One ultrasonic motor 2
Does not resonate.

As a result, each of the ultrasonic motors 2 and 3 can be independently driven only by signals (independent signals) output from the driver 1 via one output line 7. Therefore, for example, when the present invention is applied to the angle adjustment of a door mirror of an automobile, one ultrasonic motor 2 can move up and down and the other ultrasonic motor 3 can move left and right. When the vehicle is installed on the vehicle cabin side, the number of wire harnesses passing through the hinge portion of the door can be reduced.

When the operator wants to move at a stroke in a diagonal direction such as diagonally upward to the right, both switches must be pressed simultaneously. In such a case, both driving frequency output circuits 1a and 1
The drive frequency signals f1 and f2 are simultaneously output from b. In this case, the two drive frequency signals f1 and f2 are superimposed by the mixer 4 and a signal (having one waveform as shown in FIG. 3) from the output terminal 6 of the driver 1 through one output line 7. (Superimposed signal) is output.

One output signal obtained by superimposing the respective drive frequencies is input to each of the ultrasonic motors 2 and 3, and the one output signal includes the components of the respective drive frequency signals f1 and f2. One ultrasonic motor 2 can resonate only with the corresponding drive frequency signal f1, and the other ultrasonic motor 3 can resonate only with the corresponding drive frequency signal f2. Therefore, with only one output line 7 (one output system),
A plurality of independent ultrasonic motors can be driven simultaneously.

In the above description, two ultrasonic motors 2
・ The example using 3 was shown, but it is not limited to 2 units.
The present invention is also applicable to a configuration in which three or more ultrasonic motors are connected to each other in parallel. As one example of such a case, an ultrasonic motor 5 connected as a third unit is shown by imaginary lines in FIG. The driver 1 is provided with a drive frequency output circuit 1c for outputting a drive frequency signal f3 corresponding to the resonance frequency of the ultrasonic motor 5, and the drive frequency signal f3 is supplied from the driver 1 via the mixer 4. Is output.

Therefore, the three ultrasonic motors 2.3
5 are simultaneously driven, the driver 1 outputs the superposed output signals of the respective drive frequency signals f1, f2, f3 to the respective ultrasonic motors 2, 3, 5 via one output line 7. The ultrasonic motors 2, 3, and 5 are driven by driving frequency signals corresponding to the respective resonance frequencies.

Further, the present invention can be similarly applied to a case where four or more ultrasonic motors are connected. Further, the present invention is not limited to the above-described angle adjustment of the door mirror, and can be applied to various other motor devices. In the case of an automobile, for example, a wiper motor (front / rear) or a power window motor (each side window) can be considered.

The circuits in the control circuit to which the present invention is applied are not limited to the above-described example, but may be, for example, the driving frequency output circuits 1a, 1b, and 1 described above.
The same number of oscillation circuits can be provided in place of c, and a power amplifier circuit (such as a transformer) can be provided in place of the mixer 4. Also in this case, the waveform of the output voltage of the power amplifier circuit is as shown in FIG. 3 in the above-described example, and each of the ultrasonic motors 2, 3, and 5 can be driven at the corresponding drive frequency.

The ultrasonic motor control circuit according to the present invention can be applied to an ultrasonic motor using either a traveling wave type or a standing wave type driving system.

In the illustrated example, a combination of one driver 1 and one output line 7 is shown. However, according to the present invention, the present invention is not limited to the illustrated example, and a plurality of drivers may be provided. May be used. In that case, the same number of driver connection lines as the number of each driver exist, but these driver connection lines are collectively connected to one end of one output line 7, and the other end of the output line 7 The ultrasonic motors 2, 3, and 5 may be connected in the same manner as in the illustrated example. Even in this case, for example, only one output line from the control panel to the branch point to each ultrasonic motor is sufficient, which is effective for simplifying wiring when the length is long, and noise is reduced by simplifying wiring. Can be prevented.

[0021]

As described above, according to the present invention, the number of drivers when a plurality of ultrasonic motors are provided can be reduced as much as possible, and it is not necessary to provide the same number of drivers as the number of ultrasonic motors. Since the number of output lines from the driver to be connected can be reduced to one, and the wiring between the driver and each ultrasonic motor can be omitted as much as possible, the weight, size, and cost of the entire system can be reduced. Not only can be improved, but also the effect of noise can be prevented by simplifying the wiring.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a control circuit for an ultrasonic motor to which the present invention is applied.

FIG. 2 is a diagram showing each waveform of a driving frequency signal for driving each ultrasonic motor.

FIG. 3 is a diagram showing a waveform in which each driving frequency signal is superimposed.

[Description of Signs] 1 Driver 1a ・ 1b ・ 1c Driving frequency output circuit 2.3 Ultrasonic motor 4 Mixer 5 Ultrasonic motor 6 Output terminal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroki Kuroiwa 1-2681, Hirosawa-cho, Kiryu-shi, Gunma Co., Ltd. Inside the Mitsuba Corporation (72) Inventor Junichi Saito 1-2681-1, Hirosawa-cho, Kiryu-shi, Gunma Co., Ltd. F Terms (reference) 5H680 AA00 AA18 AA19 BB03 BB19 BB20 BC07 CC06 CC07 FF26

Claims (1)

[Claims] An ultrasonic motor control circuit for driving a plurality of ultrasonic motors having different mechanical resonance frequencies from each other, the control circuit corresponding to each of the mechanical resonance frequencies of the plurality of ultrasonic motors. Each drive frequency output means for outputting a drive frequency signal, and one output line provided between each drive frequency output means and the plurality of ultrasonic motors; each drive frequency output means The plurality of ultrasonic motors are collectively input to the output line and the plurality of ultrasonic motors are connected in parallel to the output line, and the plurality of ultrasonic motors are independently driven. Each drive frequency signal is independently output to the output line, and when simultaneously driving the plurality of ultrasonic motors in any combination, the corresponding one of the drive frequency signals is superimposed. A control circuit for the ultrasonic motor.