JPH09285151A - Ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to more accurately detect vibration by clamping a conductor connected to an elastic body as common ground between conductors used for taking electric continuity from a drive electrode of an piezoelectric body and a vibration detection electrode to the outside respectively. SOLUTION: A flexible printed wiring board 6 is arranged to a piezoelectric body 1 and is respectively connected to a drive electrode 4 and an electric body 2 as common ground through a drive electrode 4 and an electric body 2 as common ground through a drive electrode connecting portion 7 and also connected to a detecting electrode 5 through a ground connecting portion 8 and a detecting electrode connecting portion 9 respectively with soldering or a conductive adhesive. Electrical leader lines are made so as to position a common ground line 10 between a drive conductor 11 and detection conductor 12 and are connected to an external drive circuit. By doing this, a sine wave signal from the drive detection electrode 5 has a peak voltage of 1/10 to 1/2 of the sine wave drive voltage applied to the drive electrode 4, so that the effect of the drive voltage on vibration detection signal is absorbed by the ground line and thus more accurate vibration and detection can be performed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ultrasonic motor mounted on various information devices.

[0002]

2. Description of the Related Art Conventionally, a means for applying a voltage to a piezoelectric body as a drive source of an ultrasonic motor is disclosed in Japanese Patent Laid-Open No. 62-2605.
The one described in Japanese Patent Publication No. 67 is known.

FIG. 5 shows a means for applying a voltage to the piezoelectric body of the ultrasonic motor. In FIG. 5, a connecting portion 29 for connecting the drive electrode and the vibration detecting electrode on the piezoelectric body is arranged on the flexible P plate 28.
Pattern is formed and the extraction unit 30 is connected to an external drive circuit.

[0004]

The sinusoidal drive voltage applied to the drive electrodes is usually 2 to 10 times higher than the sinusoidal vibration detection signal from the vibration detection electrodes. If the conducting wires for taking out electrical continuity to the outside are adjacent to each other, they will interfere with each other and the vibration detection signal will not be accurate, which may cause a malfunction when control is performed using the vibration detection signal. .

Further, when there are a plurality of vibration detection electrodes and their positions are displaced from each other with respect to the vibration waveform of the vibrating body, there is a phase difference between the respective vibration detection signals and they interfere with each other, so that the vibration detection signals are accurately Will cause the lack of.

Further, since the drive electrode and the vibration detection electrode are usually adjacent to each other on the piezoelectric body, the signal of the vibration detection electrode interferes with the drive voltage for the above-mentioned reason, so that accurate vibration information is not obtained. Of course, similarly, in a piezoelectric body in which a plurality of vibration detection electrodes are adjacent to each other, respective signals interfere with each other and accurate vibration information cannot be obtained.

It is an object of the present invention to realize more accurate vibration detection in such a method of extracting a vibration detection signal of a vibrating body which is a drive source of an ultrasonic motor.

[0008]

In the method of extracting electrodes of an ultrasonic motor according to the present invention, a common ground is provided between a lead wire for extracting a drive electrode and a lead wire for extracting a vibration detecting electrode, and between lead wires for a plurality of vibration detecting electrodes. By arranging the lead wires for extraction, it is possible to suppress the interference of signals with each other and realize more accurate vibration detection.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention amplifies the vibration amplitude of a piezoelectric body between a lead wire from a drive electrode and a lead wire from a vibration detection electrode on a piezoelectric body which is a drive source of an ultrasonic motor. Therefore, it is fixed by adhesion, etc., and the conductor for ground extraction from the elastic body, which is a common ground, is sandwiched, and the influence of the drive voltage applied to the drive electrode on the signal from the vibration detection electrode is absorbed by the conductor for ground extraction. , Has the effect of performing more accurate vibration detection.

Further, in an ultrasonic motor having a plurality of vibration detecting electrodes for detecting the vibration of the vibrating body, the elastic body which is a common ground between the lead wires taken out from the respective vibration detecting electrodes is used. It has an action of arranging an extraction lead wire, suppressing interference of vibration detection signals with each other, and performing more accurate vibration detection.

Further, an electrode which is not involved in driving or detecting is provided between the drive electrode on the piezoelectric body which is the drive source of the ultrasonic motor and the vibration detection electrode and is connected to the elastic body which is a common ground. This has the effect of suppressing the influence of the drive voltage on the signal from the vibration detection electrode and obtaining more accurate vibration information.

Further, when a plurality of vibration detection electrodes provided on the piezoelectric body are arranged adjacent to each other, both the drive and detection are performed between the respective electrodes so that the vibration detection signals do not interfere with each other. An electrode that does not participate is disposed, and this electrode and the elastic body that is a common ground are short-circuited to obtain more accurate vibration information.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, a vibrating body 3 is formed by fixing an elastic body 2 for amplifying the vibration to a piezoelectric body 1 serving as a vibration source of an ultrasonic motor. In order to generate three elastic traveling waves in the circumferential direction on the surface of the vibrating body 3 on the piezoelectric body 1, sinusoidal frequency voltages having a phase difference of 90 ° from each other are applied to the two drive electrodes 4. To do. The vibration speed control of the ultrasonic motor is performed using a sinusoidal signal from the vibration detection electrode 5 that converts the vibration thus generated into the movement amount of the electric charge. At this time, in order to apply a voltage from the outside, a flexible P plate 6 is arranged in the vicinity of the inner peripheral portion where the vibration amplitude of the piezoelectric body 1 is small, and the drive electrode 4 is a common ground via the drive electrode connecting portion 7. The elastic body 2 is connected to the detection electrode 5 via a ground connection portion 8 and a detection electrode connection portion 9 by soldering or a conductive adhesive, respectively.
A common ground wire 1 between the drive conductor 11 and the detection conductor 12.
It is electrically taken out so that 0 is located and connected to an external drive circuit. The sinusoidal signal of the vibration detecting electrode 5 is 10 to 2 of the sinusoidal driving voltage applied to the driving electrode 4.
Since the peak voltage is one-half, the influence of the drive voltage on the vibration detection signal can be absorbed by the ground line and more accurate vibration detection can be performed.

(Embodiment 2) In FIG. 2, in order to detect the vibration of the vibrating body 3 which is the vibration source of the ultrasonic motor, two vibrations are detected on the piezoelectric body 1 fixed on the vibrating body 3. In the ultrasonic motor having the electrodes 13, the ground wire 18 taken out from the elastic body 2 which is a common ground via the ground connection portion 14 is sandwiched between the respective detection lead wires 17 from the vibration detection electrodes 13. Further, the ground line 18 absorbs the influence of mutual vibration detection signals on each other, so that more accurate vibration detection can be performed.
At this time, it goes without saying that the ground line 18 is also arranged between the drive conductor 19 and the detection conductor 17 as described in the first embodiment.

(Embodiment 3) In FIG. 3, a vibrating body 3 is formed by fixing an elastic body 2 for amplifying the vibration to a piezoelectric body 1 serving as a vibration source of an ultrasonic motor. In order to generate three elastic traveling waves in the circumferential direction on the surface of the vibrating body 3 on the piezoelectric body 1, sinusoidal frequency voltages having a phase difference of 90 ° from each other are applied to the two drive electrodes 4. To do. The vibration speed control of the ultrasonic motor is performed using a sinusoidal signal from the vibration detection electrode 5 that converts the vibration thus generated into a change in the amount of electric charge. An electrode that is not involved in driving or detection is formed between the drive electrode 4 and the vibration detection electrode 21,
The elastic body 2 that is a common ground is connected via a ground wire 22. At this time, in order to establish electrical continuity with an external drive circuit, the flat cable 23 is connected to the vicinity of the inner peripheral portion of the piezoelectric body 1 where the vibration amplitude is small by soldering in order of the electrodes or by a conductive adhesive. By doing so, a ground wire is arranged between the drive electrode 4 and the vibration detection electrode 20, and the sinusoidal drive voltage applied to the drive electrode 4 detects the sinusoidal vibration from the drive detection electrode 20. The influence on the signal can be suppressed, and more accurate vibration detection can be performed.

(Embodiment 4) In FIG. 4, in order to detect the vibration of the vibrating body 3 which is the vibration source of the ultrasonic motor, two vibration detecting electrodes 2 are provided on the piezoelectric body 1 fixed on the vibrating body.
In the ultrasonic motor having No. 5, a ground electrode 24 which is not involved in driving or detection is formed between the two vibration detection electrodes 25. As described in the third embodiment, a similar ground electrode 24 is arranged between the drive electrode 4 on the piezoelectric body 1 and the vibration detection electrode 25, and a ground wire is connected to the elastic body 2 which is a common ground. Connect via 26. At this time, in order to establish electrical conduction with an external drive circuit, the flat cable 27 is connected to the inner peripheral portion of the piezoelectric body 1 having a small vibration amplitude by soldering in order of the electrodes or by a conductive adhesive. As a result, a ground is arranged between the two vibration detection electrodes 25 and between the drive electrode 4 and the vibration detection electrode 25. The influence of mutual interference between the sinusoidal vibration detection signals It is possible to suppress the influence of the drive voltage of 1) on the sinusoidal vibration detection signal, and more accurate vibration detection can be performed.

[0018]

As described above, according to the present invention, a more stable and accurate vibration detection signal can be obtained when the piezoelectric body, which is the drive source of the ultrasonic motor, is electrically connected to the outside. More accurate control can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an electrode extraction structure showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an electrode lead-out structure showing a second embodiment of the present invention.

FIG. 3 is a perspective view showing a piezoelectric electrode structure showing a third embodiment of the present invention.

FIG. 4 is a perspective view showing a piezoelectric electrode structure showing a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a means for applying a voltage to a piezoelectric body of an ultrasonic motor.

[Explanation of symbols]

 1 Piezoelectric body 2 Elastic body 3 Vibrating body 4 Driving electrode 5,13,20,25 Vibration detection electrode 6,16,28 Flexible P plate 7 Driving electrode connection part 8,14 Ground connection part 9,15 Detection electrode connection part 10, 18,22 Ground wire 11,19 Drive lead wire 12,17 Detection lead wire 21,24,26 Ground electrode 23,27 Flat cable 29 Electrode connection part 30 Extraction part

Claims (4)

[Claims] 1. A drive electrode for applying an electric field from the outside to excite an elastic traveling wave serving as a drive source for an ultrasonic motor,
In an ultrasonic motor having a vibrating body in which an elastic body for amplifying the vibration amount is fixed by adhesion or the like to a piezoelectric body having a vibration detecting electrode for converting the vibration amount into a moving amount of electric charge, An ultrasonic motor characterized in that a conductor wire connected to the elastic body, which is a common ground, is sandwiched between conductor wires used to electrically connect the drive electrode and the vibration detection electrode of the piezoelectric body to the outside. . 2. An ultrasonic motor having a plurality of vibration detecting electrodes for detecting vibration of a vibrating body, which is provided on a piezoelectric body, and is used to electrically connect the respective vibration detecting electrodes to the outside. An ultrasonic motor characterized in that a conductor connected to an elastic body that is a common ground is sandwiched between the conductors. 3. A drive electrode for applying an electric field from the outside to excite an elastic traveling wave serving as a drive source of an ultrasonic motor,
In an ultrasonic motor using a vibrating body as a driving source, a piezoelectric body having a vibration detection electrode for converting the amount of vibration into a moving amount of electric charge and an elastic body for amplifying the amount of vibration fixed to the piezoelectric body by adhesion or the like. An ultrasonic motor characterized in that an electrode that is not involved in driving or detection is provided between the drive electrode of the piezoelectric body and the vibration detection electrode, and the electrode and the elastic body that is a common ground are short-circuited. 4. An ultrasonic motor in which a vibration detecting electrode for detecting vibration of a vibrating body on a piezoelectric body is divided into a plurality of parts.
An ultrasonic motor characterized in that an electrode that is not involved in driving or detection is provided between each vibration detection electrode, and is short-circuited to an elastic body that is a ground common to the electrodes.