JPH04183282A - Drive controller for ultrasonic motor - Google Patents

Abstract

PURPOSE:To apply a higher pulse voltage than a normal driving voltage irrespective of whether it is a vibration deviation state and to surely start an ultrasonic motor by providing high frequency voltage generating means for generating a high frequency voltage to be applied to the motor. CONSTITUTION:When a start signal generator 10 outputs a start signal at a time t0, a pulse generator 11 generates a pulse signal for generating a pulse voltage higher than a driving voltage at a normal time. In this case, since an MPX 13 is so switched as to output a pulse signal from the generator 11, the signal is output. The signal is amplified to a pulse driving voltage by amplifiers 15a, 15b, and applied to driving electrodes 1b-R, 1b-L of an ultrasonic motor M. The pulse driving voltage at the time of starting is higher than the driving voltage at the normal time, the pulse voltage having a high frequency, and the motor M in which high vibration energy is applied, is stably started without falling in a vibration deviation state.

Description

[Detailed description of the invention] A. Industrial application field The present invention relates to a drive control device for an ultrasonic motor.

B. Conventional technology A progressive vibration wave type ultrasonic motor is disclosed in, for example, Japanese Patent Application Laid-open No. 1986-
As shown in Japanese Patent No. 111609, the bending vibration generated when an alternating current voltage is applied to a piezoelectric material is used to generate progressive vibration waves in an elastic body to which a piezoelectric material is attached. This is a motor that operates frictionally by bringing the rotor into pressure contact.

This ultrasonic motor has the following characteristics: IEICE Journal ■o1.7
0. No, 7. pp717-pp720 (July 1987
As shown in the following issue, it has a characteristic that when the load exceeds the rated value, it deviates from resonance and stops. If the ultrasonic motor stops under such conditions, the voltage of the drive electrode of the ultrasonic motor (
The phase difference between the voltage of the monitor electrode (hereinafter simply referred to as the drive voltage) and the voltage of the monitor electrode (hereinafter simply referred to as the monitor voltage) deviates from the value during normal rotation, and the vibration of the stator almost disappears (
Hereinafter, in this specification, such a state will be referred to as a vibration deviation state). This vibration deviation state is likely to occur when the expiration voltage is lower than a predetermined value.

C0 Problem to be Solved by the Invention When an ultrasonic motor having such characteristics is started by gradually increasing the drive voltage for a time longer than one cycle of the drive frequency as shown in Fig. 4, the There is a problem that the device falls into a state of vibration deviation and does not start.

Furthermore, in order to escape from this vibration deviation state, the load must be released and the drive frequency must be set higher than the resonant frequency and restarted. but.

A clutch mechanism is required to release the load,
Not only is the device complicated and large, but it takes time to restart it.

An object of the present invention is to provide a drive control device that reliably starts an ultrasonic motor by applying a pulse voltage higher than a normal active voltage to the ultrasonic motor, regardless of whether the ultrasonic motor is in a vibration deviation state. It is in.

The present invention will be explained in conjunction with FIG. 1 showing an embodiment of the present invention.Means for Solving the Problems 00 The present invention includes a high-frequency voltage generating means 12 that generates a high-frequency voltage to be applied to an ultrasonic motor M. Ultrasonic motor N
1, temporary control device number 2 is applied.

A pulse voltage generating means 11 that generates a pulse voltage higher than the high frequency voltage, a starting signal generating means 10 that outputs a starting signal for a predetermined time when starting the ultrasonic motor M, and this starting signal generating means 10 The above object is achieved by comprising a switching means 13 that switches the voltage applied to the ultrasonic motor M from the high frequency voltage of the high frequency voltage generating means 12 to the pulse voltage of the pulse voltage generating means 11 when the starting signal is not output from the is achieved.

When the activation signal is output from the E3 action activation signal generator 10,
The voltage applied to the ultrasonic motor M is switched from the high frequency voltage of the high frequency voltage generating means 12 to the pulse voltage of the pulse voltage generating means 11 by the switching means 13. As a result, the pulse voltage of the pulse generating means 11 is applied to the ultrasonic motor M at the time of starting, and the ultrasonic motor M is reliably started without falling into a state of vibration deviation during starting.

In the above-mentioned sections and Section E that describe the present invention in detail, figures of embodiments are used to make the present invention easier to understand, but the present invention is not limited to the embodiments.

F. Embodiment FIG. 1 is a block diagram showing the overall configuration of one embodiment, and FIG. 2 is an exploded view of the ultrasonic motor.

The drive control device for the ultrasonic motor M is composed of five devices shown in FIG. 1o is a starting signal generating device, which generates a starting signal when the ultrasonic motor M is started. A pulse generator 11 generates a pulse signal when the activation signal is supplied from the activation signal generator 10. This pulse signal generates a pulsed traction voltage that is higher in voltage than the active voltage in steady state. Reference numeral 12 denotes a high-frequency signal generator, which generates a high-frequency signal that determines the drive voltage and active frequency in steady state. Numeral 13 is a multiplexer (hereinafter referred to as MPX) for switching the signal, which outputs the pulse signal from the pulse generator 11 when the activation signal is supplied from the activation signal generator 1o, and otherwise outputs the pulse signal from the pulse generator 11; A high frequency signal from the signal generator 12 is output. 1
4 is a phase shifter, which shifts the signal phase from MPX 13 to +π// in accordance with a rotation direction command of an ultrasonic motor M (not shown).
2 or −π/2. Furthermore, 15a, 15
Reference numeral b denotes an amplifier, which amplifies the power of the signal from the M P X 13 and the signal from the phase shifter 14 whose phase is shifted by +π/2 or −π/2 from that signal.

The ultrasonic motor M has a stator 1 and a rotor 2 shown in FIG.
It consists of Furthermore, stator 1.

The rotor 2 is composed of an elastic body 1a and a piezoelectric body 1b bonded to the elastic body 1a, and the rotor 2 has a ring-shaped rotor base material 2a.
and a slider material 2b bonded to the rotor base material 2a.

The piezoelectric body 1b of the ultrasonic motor M has electrodes 1b-R, 1b
-L, 1b-G, and lb-M are provided. Electrode 1b
-R and 1b-L are active electrodes.

They are connected to amplifiers 15a and 15b, respectively, and drive voltages are applied thereto. Electrode 1b-G is a ground electrode and is grounded. Further, the upper electrode -M is a monitor electrode, and the AC and ft voltages correspond to the vibrations of the elastic body 1a.

That is, a monitor voltage is generated.

FIG. 3 is a time chart showing changes in each signal when the ultrasonic motor M is started by the drive control device. The operation of the drive control device will be explained with reference to this time chart.

At time 10, when the activation signal is output from the activation signal generation device 10, the pulse generation device 11 generates a pulse signal for generating a pulse voltage higher than the drive voltage during normal operation. At this time, the MPX 13 has been switched to output the pulse signal from the pulse generator 11, so the pulse signal is output from the MPX 13 as shown in FIG. This pulse signal is transmitted to the amplifiers 15a and 15.
b is amplified into a pulse drive voltage and applied to the drive electrodes 1b-R and 1b-L of the ultrasonic motor M.

This pulse drive voltage at the time of startup is higher than the active voltage at steady state, and is also a pulse voltage with a high frequency, and the ultrasonic motor M given such high vibration energy does not fall into a state of vibration deviation. .

Starts stably. Furthermore, even if the device is stopped in a vibration deviation state before starting, it can easily escape from the vibration deviation state and start by applying a high pulse voltage such as 2.

At time t1 after starting the ultrasonic motor M, the MPX 13 switches to output the high frequency signal from the high frequency generator 12, so as shown in FIG. , phase shifter 14 and amplifier 15a.

15b, the amplified voltages are amplified into a pair of drive voltages having phases different from each other by +π/2 or 1π/2, and are applied to the drive electrodes 1b-R and 1b-L of the ultrasonic motor M. That is, the ultrasonic motor M continues to rotate with the drive voltage and drive frequency applied during normal operation.

As explained above, when starting the ultrasonic motor, a pulse voltage higher than the normal drive voltage is applied, so that the ultrasonic motor can be started reliably without falling into a vibration deviation state, and the drive control device Improved reliability. In addition, even if the device is in the pre-start L: vibration deviation state, it can be easily started after exiting the state.

Although the above embodiments have been described using a rotary type ultrasonic motor as an example, the present invention can also be applied to a linear type ultrasonic motor.

Further, in the above embodiment, when the ultrasonic motor M is started, the pulse signal of the pulse generator 11 and the high frequency signal generator 12 are
The high frequency signal of generate,
The circumferential drive voltage may be switched by a switch and applied to the ultrasonic motor.

In the configuration of the above embodiment, the high frequency signal generator 12
constitutes a high frequency voltage generating means, the pulse generating device 11 constitutes a pulse voltage generating means, the starting signal generating device 10 constitutes a starting signal generating means, and the multiplexer 13 constitutes a switching means.

G0 Detailed Description of the Invention According to the present invention, when starting the ultrasonic motor, a pulse voltage higher than the high frequency voltage in the steady state is applied, so that the ultrasonic motor is in a vibration deviation state when starting. This improves the reliability of the active control device. Furthermore, even if the device is in a vibration deviation state before starting, it can be easily started after getting out of that state.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, Fig. 2 is a sectional view of the ultrasonic motor, and Fig. 3 is a time chart showing changes in output signals of various parts of the device when the ultrasonic motor is started. , FIG. 4 is a time chart showing changes in drive voltage when starting an ultrasonic motor using a conventional device. 10: Starting signal generator 11: Pulse generator 12:
High frequency signal generator 13: MPX14: Phase shifter
15a, 15b: Amplifier M: Ultrasonic motor

Claims (1)

[Scope of Claims] An ultrasonic motor drive control device comprising a high-frequency voltage generating means for generating a high-frequency voltage to be applied to the ultrasonic motor, comprising: a pulse voltage generator for generating a pulse voltage higher than the high-frequency voltage; means for outputting a starting signal for a predetermined period of time when starting the ultrasonic motor; and when the starting signal is output from the starting signal generating means, the voltage to be applied to the ultrasonic motor is set to the high frequency voltage. A drive control device for an ultrasonic motor, comprising: switching means for switching from the high frequency voltage of the voltage generating means to the pulse voltage of the pulse voltage generating means.