JPH07101996B2 - Ultrasonic motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a position detection function or speed that can be used mainly in electrical equipment such as automobiles and aircraft, OA fields such as printers, FA fields such as robots, and the like. The present invention relates to a motor having a detection function.

2. Description of the Related Art The mounting position of a means for detecting the speed or position of a moving body of an ultrasonic motor is not determined in consideration of the magnitude of the vibration amplitude of the vibrating body. In most cases, the position detecting means is installed in a place where the vibration amplitude is not zero or is relatively large.

Therefore, since the vibration of the vibrating body is always transmitted to the velocity or position detecting means of the moving body, the mechanical strength of the velocity or position detecting means of the moving body is rapidly deteriorated and the durability is improved. There was a problem of poor sex.

Further, due to this vibration, it is difficult to detect the position with high accuracy.

The object of the present invention is that the vibration of the vibrating body is not transmitted to the speed or position detecting means of the moving body, and the detecting means has excellent durability and has a highly accurate position detecting or speed detecting function of the moving body. It is to provide an ultrasonic motor.

Means for Solving the Problems The present invention configures a vibrating body by concentrically bonding a disc-type elastic body and a disc-type piezoelectric body, and a moving body is installed by pressingly contacting the vibrating body, By exciting the bending vibration mode of the vibrating body as a traveling wave, the moving body is moved and the displacement distribution of the vibrating body has a part that does not vibrate at all, and the amplitude of the vibrating body becomes zero. The ultrasonic motor is provided with a detecting unit for detecting the position or speed of the moving body at the node.

Action With the above configuration, the detecting means for detecting the position or speed of the moving body does not receive the vibration of the vibrating body.
The durability and the speed or position of the moving body can be detected with high accuracy.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is an amplitude distribution in the radial direction of the vibrating body 1 when a piezoelectric body is excited by applying a voltage, where A is the maximum amplitude portion,
B is a node where the amplitude is always zero, and the node is shown in the dotted line in FIG.

FIG. 3 is an exploded perspective view of the vibrating body 1 and the moving body 2, and a part of the moving body 2 is a sectional view.

Comb-shaped teeth 6 for amplifying the amplitude are provided at the circumferential portion (A in FIG. 2) where the amplitude of the vibrating body 1 is maximum. Mobile 2
The radius is designed to be smaller than the radius of the node portion, and the lining material 11 having a large friction coefficient is attached to the contact portion with the vibrating body. Furthermore, the moving body 2 is installed by pressing the spring 9 on the vibrating body 1 with the screw 10 under pressure. On the circumferential portion of the moving body 2, as shown in FIG. 1, N-poles and S-poles are alternately magnetized to form magnetized portions 3.

Reference numeral 4 is a magnetic detection element, and for example, a magnetic resistance element or the like can be used. The magnetic detection element 4 is installed at the node portion 5 of the vibrating body 1 so as to be able to detect a magnetic field change by the magnetizing portion 3.

As shown in Japanese Patent Application Laid-Open No. 60-190178, the piezoelectric body has a disk shape on the bottom surface of the vibrating body 2, and is divided into, for example, 8 parts radially.
Piezoelectric bodies 7 and 8 polarized in opposite directions at intervals of 45 ° are spatially shifted in phase by 90 ° from each other and bonded to the vibrating body 1, and the piezoelectric bodies 7 and 8 are temporally shifted in phase by 90 °. Different numbers
Apply an AC signal of 10KHz. By applying an AC signal,
A standing wave is generated in each of the piezoelectric bodies 7 and 8, and the two standing waves are combined to generate a traveling wave traveling in the circumferential direction of the vibrating body 1. The amplitude of the traveling wave is amplified by the comb-like teeth 6, and the moving body 2 that is installed under pressure on the vibrating body 1 is effectively rotated.
Further, the rotation speed or the rotation angle of the moving body 2 is detected by the magnetic detection element 4 to control the rotation speed or the rotating position of the moving body 2.

FIG. 4 shows an embodiment of rotational position control.

For example, the two detection elements 4 of the magnetic field detection section are installed so that the magnetic field changes of the magnetized section 3 of the vibrating body 1 are spatially 90 ° out of phase. In the position detection circuit 12, the two signals that have detected the magnetic field change are wave-shaped to form two square waves, and if the signals are A and B, the signals A and B, the rising and the rising of each of them. The direction of rotation of the moving body 2 is detected by detecting the signal level of each other at the time of falling, and the rotating position of the moving body 2 is detected by a digital value by counting up or down the up-down counter provided in the position detection circuit 12. Detect 15

In the comparison circuit 13, the preset target rotational position 16 and the current rotational position 15 are compared, and based on the result, the ultrasonic motor drive circuit 14 is turned on / off command signal 17 for the ultrasonic motor. And the rotation direction command signal 18 is output.

FIG. 5 is a functional explanatory diagram of an example of the ultrasonic motor drive circuit.

The oscillator 21 outputs an exciting frequency and connects it to the amplifier 28 and the phase shifter 23 via the analog switch 22.
The phase shifter 23 outputs the signal from the oscillator 21 with a 90 ° phase shift. A 90 ° phase-shifted signal is a non-inverting amplifier
24, and the outputs of the non-inverting amplifier 24 and the inverting amplifier 25 are connected to the inverting amplifier 25 and the amplifier 27 via the analog switch 26.
Connect to.

Outputs 19 and 20 of the amplifiers 27 and 28 are drive signals for exciting the vibrating body 1 having phases different from each other by 90 °, and the phase difference between the outputs 19 and 20 is obtained by switching the signal of the rotation direction command signal 18. It changes from + 90 ° to −90 °, the direction of the traveling wave of the vibrating body is reversed, and the direction of rotation is reversed.

An output ON / OFF signal 17 from the comparison circuit 13 switches the drive signals 19 and 20.

With such a configuration, by comparing the current rotational position 15 of the moving body 2 and the target rotational position 16, the position of the vibrating body 2 can be rotated to the target rotational position 16 and stopped.

In the embodiment shown in FIG. 5, the rotation speed of the moving body 2 is not detected, but the rotation speed is detected and the rotation speed is changed according to the difference between the current rotation angle and the target angle. It is also possible to perform the position control in consideration of the rotation speed such as the method of performing.

Further, the position detecting element is not limited to being placed at one point on the node, and for example, the sliding portion of the potentiometer may be arranged over the entire node.

EFFECTS OF THE INVENTION As described above, the ultrasonic motor according to the present invention includes the vibrating body 1 and the moving body 2 installed in pressure contact with the vibrating body 1, and includes the means 4 for detecting the rotation speed or the position. The moving body is installed at the node 5 of the elastic vibration of the vibrating body, the vibration of the vibrating body is not transmitted to the detecting means of the speed or position of the moving body, and the detecting means has excellent durability and high precision. It is possible to configure an ultrasonic motor having a function of detecting the speed or the position.

Then, the speed or position of the moving body can be controlled on the basis of the output of the detecting means, and the speed or position of the moving body can be controlled, and the reduction mechanism utilizing the thin, lightweight, low speed, and high torque features of the ultrasonic motor. It is possible to realize an ultrasonic actuator without any. Thus, the practical effect of specifying the installation position of the speed or position detection means is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view of an ultrasonic motor according to an embodiment of the present invention, FIG. 2 is a distribution diagram of displacement amplitude in a radial direction of a vibration body of the motor, and FIG. 3 is an exploded perspective view of the motor. FIG. 5 is a block diagram of the rotational position control of the motor, and FIG. 5 is a block diagram of the ultrasonic motor drive circuit in FIG. 1 ... Vibrating body, 2 ... Moving body, 3 ... Magnetization part, 4 ... Magnetic detection element, 5 ... Nodal part, 6 ... Comb tooth, 7,8 ... Piezoelectric body, 9 ... Spring, 10 ... screw, 11 ... lining material,
15 …… Current rotation position, 16 …… Target rotation position, 17 …… ON / O
FF command signal, 18 ... Rotation direction command signal, 19, 20 ... Ultrasonic motor drive signal, 22 ... Analog switch, 26 ... Analog switch, 24 ... Non-inverting amplifier, 25 ... Inversion amplifier, 50 ... … Elastic body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Kawamura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-59-20447 (JP, A)

Claims (1)

[Claims] 1. A moving body (2) having a vibrating body (1) for generating a traveling wave and a magnetizing part (3), which is made of a piezoelectric material, and is installed in pressure contact with the vibrating body (1). ) And a means (4) for detecting the magnetic field of the magnetized portion (3) of the moving body (2), the means (4) being a node portion (5) for elastic vibration of the vibrating body (1). An ultrasonic motor characterized by being installed in.