JP2002153080A - Ultrasonic motor and electronic apparatus provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small size and easily operable ultrasonic motor having a sophisticated encoder function for detecting rotating angle and rotating speed and a control function. SOLUTION: A piezoelectric element 3 is provided on a supporting plate 2. A moving body 5 mounted to freely rotate is disposed on a projection 4a of a vibration body 4 connected to the piezoelectric element 3. A pressurizing means 6 places the moving body 5 with pressure in contact with the vibration body 4. Moreover, a motor drive circuit 9 and a regulation capacitor are provided for generating an AC voltage to be supplied to the piezoelectric element from the DC power supply. The moving body 5 is connected in direct with an encoder disc 20. On the supporting plate 2, a wiring means 7 for fixing each element through connection of the electrical system is integrated. The wiring means 7 is provided with a motor drive circuit 9 and a rotation detecting element 21. The wiring means 7 and a piezoelectric body are connected with a lead as the extended portion of the wiring, and an AC voltage is fed thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, an electronic device using an ultrasonic motor, such as a clock, a measuring device, an industrial robot, a factory automation device, and an optical communication device, and an optical device.

[0002]

2. Description of the Related Art In recent years, ultrasonic motors are characterized by their small size and light weight, and are used in small precision equipment such as watches and optical communication equipment.

A conventional ultrasonic motor 101 is shown in FIGS.
As shown in the schematic diagram of FIG. 1 and the block diagram of FIG. 8, the piezoelectric element 3, the vibrating body 4 connected to the piezoelectric element 3 on the support plate 2, and the movement rotatably mounted on the projection 8 of the vibrating body 4. It comprises a body (rotor) 105 and pressure means 6 for pressing the moving body 105 against the vibrating body 4. Further, a drive circuit 9 for generating an AC voltage supplied from the DC power supply to the piezoelectric element and an adjustment capacitor 11 are provided.

As an example of a conventional ultrasonic motor,
JP-A-7-170772 and the like.

[0005]

However, the conventional ultrasonic motor has no means for detecting the rotation angle and the rotation speed, and if a positioning control function is required to incorporate the ultrasonic motor into various devices, a separate ultrasonic motor is required. It was necessary to take measures such as connecting a rotary encoder or the like to a shaft via a gear or a mechanical joint. Therefore, there is a problem that it is difficult to reduce the size of the device. In addition, there is a problem in that the number of parts and the number of assembling steps increase, resulting in an increase in cost.

[0006]

According to the present invention, there is provided a piezoelectric element which expands and contracts by application of an alternating current, a vibrating body which vibrates in accordance with the expansion and contraction of the piezoelectric element, and a drive which is driven in accordance with the vibration of the external conductor. In the ultrasonic motor configured to be supported by a support plate, an ultrasonic motor driving unit having a moving body to be connected and a connection means for electrical connection, rotation detection for detecting rotation information of the moving body by the connection means An ultrasonic motor having an element and an encoder disk connected to the moving body.

[0007] With this, by providing an encoder disk connected to the moving body and a rotation detecting element, and by providing the rotation detecting element in the connection means, it is possible to detect rotation information such as a rotation angle and the number of rotations, and to provide a control function. However, a small ultrasonic motor can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An ultrasonic motor according to this embodiment is configured as shown in the schematic diagrams of FIGS. 1A and 1B and the configuration block diagram of FIG.

A piezoelectric element 3, a vibrating body 4 connected to the piezoelectric element 3, a moving body (rotor) 5 rotatably mounted on a projection 4a of the vibrating body 4, and a vibrating body 5 on the supporting plate 2. Body 4
And pressurizing means 6 for pressing against. Further, it includes a motor drive circuit 9 for generating an AC voltage to be supplied from the DC power supply to the piezoelectric element, and an adjustment capacitor.

An encoder disk 20 is directly connected to the moving body 5, and a connecting means (connection board) 7 for connecting an electric system and fixing each element is integrally mounted on the support plate 2. . The motor drive circuit 9 and the rotation detecting element 21 are provided on the connection means 7. The connection means 7 and the piezoelectric body are connected by a lead extending from the wiring of the connection means 7, and AC voltage is supplied. As shown in FIGS. 6A and 6B, the connection means 7 includes a metal wiring layer 41 and a resin insulation layer 4.
2, and the metal wiring layer is patterned by photolithography. In each electronic circuit (integrated circuit) and each electronic element, the lead terminal 43 and the metal wiring layer 41 of the connection means 7 are connected by soldering.

In the embodiment, a metal disk with a radially slit (grating) is used as an encoder disk, and a pair of a semiconductor light emitting element (LED) and a semiconductor light receiving element (PD) is used as a reflection type rotation detecting element. Used as The finer the pitch of the grating, the finer the resolution of the encoder. The same function can be obtained by using an encoder disk in which a radial lattice pattern is drawn on the surface of a transparent glass plate or the like and a transmission type rotation detecting element.

The rotation detecting element 21 detects the reflection of the light beam from the encoder disk 20 and outputs the signal from the encoder disk 20.
Is converted into an electric signal. The signal processing circuit 13 amplifies the electric signal of the rotation detecting element 21, adjusts the waveform, and sends a pulse signal to an externally connected counting circuit and control circuit. The rotation angle of the ultrasonic motor can be obtained by connecting a counting circuit and a control circuit to the above configuration. By providing the rotation detecting element 21 and the signal circuit 13 on the same connection means 7, the connection can be made with a minimum wiring length and there is no need to extend the wiring to the outside, so that the influence of waveform distortion, external noise, etc. Can also be prevented. Further, the overall configuration of the ultrasonic motor having the encoder function can be reduced in size.

As shown in FIGS. 5A and 5B, a wiring pattern is drawn on the connection means 7 and, at the same time, a positioning pattern 30 for indicating a fixed position of the rotation detecting element 21 is drawn. It can be installed at an accurate position, and the measurement accuracy of the rotation angle of the encoder can be kept high. The positioning pattern can be drawn by a silk print pattern in addition to the wiring pattern.

A computer-readable recording medium on which the above-described means are recorded may be used.

Second Embodiment Next, an ultrasonic motor according to a second embodiment will be described with reference to the drawings. 3A and 3B are schematic diagrams of the present embodiment, and FIG.
Is its block diagram. The ultrasonic motor according to the present embodiment includes a correction electronic element 25, a rotation detection element 21, a signal processing circuit 13, a control circuit 12, sensor elements 24 such as a voltage sensor, a current sensor, and a temperature sensor, and a microcomputer (microprocessor). 23 is provided on the connection means 7.

The voltage sensor and the current sensor measure the voltage and current of the piezoelectric element in order to know the operating state of the ultrasonic motor. Since the temperatures of the piezoelectric element and the vibrating body change the characteristics of the ultrasonic motor, it is desirable that the temperature sensor be installed at a position close to the ultrasonic motor in order to accurately measure the temperature. The correction electronic element 25 corrects a capacitance value in order to operate the ultrasonic motor most efficiently. In a conventional ultrasonic motor, a semi-fixed capacitor is used to drive the ultrasonic motor while the capacitance value once adjusted is fixed. But,
It is more desirable to change the capacitance value in accordance with a temperature change, a temporal change, a rotation speed, and the like. Therefore, an electronic element such as a PN junction diode whose capacitance changes due to a change in the width of the electric depletion layer due to the applied bias voltage is used for capacitance correction. The control circuit 12 is amplified by the signal processing circuit 13,
The signal of the rotation detecting element 21 whose waveform is shaped is counted,
The ultrasonic motor has a function of operating and stopping the ultrasonic motor at a specified angle in response to a command signal from the outside. The microcomputer 23 executes a program stored in a storage circuit for causing the ultrasonic motor to perform a complicated operation, or performs a calculation process of a parameter necessary for an optimal operation. For example, there is a case where the voltage applied to the ultrasonic motor is changed between high-speed rotation and fine positioning. Further, it is also possible to derive a correction value of the correction electronic element 25 by arithmetic processing from data such as the temperature and voltage obtained by the sensor 24 and the number of revolutions obtained by the encoder. The digital data of the correction value calculated by the microcomputer 23 is
Since the voltage is converted by the DA converter 27, a voltage can be applied to the correction electronic element to adjust the capacitance value.

The respective electronic circuits and electronic elements are integrated by IC circuit technology or hybrid IC technology,
Furthermore, it is possible to reduce the size as a whole. Many recent one-chip microcomputers have a built-in A / D converter element for detecting a voltage value from a D / A converter element or a sensor. Therefore, by using these microcomputers, the number of parts can be increased without increasing the number of parts. A small, high-performance ultrasonic motor can be realized. In addition, by using an arithmetic circuit (processor) having a high arithmetic processing capability, it is possible to share the functions of a control circuit and a counting circuit.

It is to be noted that a computer-readable recording medium on which the above-described means are recorded may be used.

[0019]

According to the present invention, it is possible to provide a compact and easy-to-handle ultrasonic motor having an advanced encoder function and a control function for detecting a rotation angle and a rotation speed. In addition, cost increases can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a block diagram showing a first embodiment of the ultrasonic motor according to the present invention.

FIG. 3 is a schematic view showing a second embodiment of the ultrasonic motor according to the present invention.

FIG. 4 is a block diagram showing a second embodiment of the ultrasonic motor according to the present invention.

FIG. 5 shows connection means according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a second embodiment of the present invention;

FIG. 7 is a schematic view showing a conventional ultrasonic motor.

FIG. 8 is a block diagram of a conventional ultrasonic motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic motor 2 Support plate 3 Piezoelectric element 4 Vibrating body 5 Moving body 6 Pressurizing means 7 Connecting means 8 Projection part 9 Drive circuit 12 Control circuit 13 Signal processing circuit 14 Spacer 15 Connection lead part 20 Encoder disk 21 Rotation detecting element Reference Signs List 23 Microcomputer 24 Sensor element 25 Correction electronic element 26 AD converter 27 DA converter 28 Arithmetic circuit 29 External connection terminal 30a Positioning pattern 30b Positioning pattern 30c Positioning pattern 30d Positioning pattern 41 Metal wiring layer 42 Resin insulating layer 43 Lead terminal 101 Conventional Ultrasonic motor 105 Moving body 107 Connection means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Iino 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba F-Term (in reference) 2F077 AA43 NN02 NN28 PP19 QV02 VV10 VV10 VV33 WW04 2F103 CA03 DA01 DA13 EA02 EA12 EA19 EA21 EB06 EB12 EB32 ED07 5H680 AA19 BB16 BC02 BC08 DD01 DD23 DD53 DD72 EE21 EE23 FF36

Claims (9)

[Claims] A piezoelectric element that expands and contracts by application of an alternating current, a vibrating body that vibrates in accordance with the expansion and contraction of the piezoelectric element, a moving body that is driven in accordance with the vibration of an external conductor,
In an ultrasonic motor configured to support an ultrasonic motor driving unit having a connection unit for electrical connection on a support plate, a rotation detection element configured to detect rotation information of the moving body by the connection unit, and the moving body An ultrasonic motor comprising: an encoder disk connected to the ultrasonic motor; 2. The connection means has a pattern for determining a position of the rotation detecting element on a surface thereof.
An ultrasonic motor as described. 3. The ultrasonic motor according to claim 1, wherein said connection means has an electronic circuit for driving said rotation detecting element and an electronic circuit for performing signal processing. 4. A motor driving circuit for supplying an alternating current to the piezoelectric element, a signal processing circuit for converting an output signal of the rotation detecting element into a signal having rotation information of the moving body, and 4. An external circuit for processing the rotation information, and a control circuit for generating a signal for driving and controlling an ultrasonic motor from the rotation information obtained by the external circuit. An ultrasonic motor as described. 5. The ultrasonic wave according to claim 4, wherein the drive circuit has a correction electronic element capable of changing a capacitance value, and the correction electronic element has an appropriate value when the ultrasonic motor is driven. motor. 6. The drive circuit has a correction electronic element capable of changing a capacitance value, wherein the correction electronic element has a capacitance calculated from rotation information obtained from the encoder disk and the rotation detection element. The ultrasonic motor according to claim 4, wherein the value is set to a value. 7. The ultrasonic motor according to claim 6, wherein said connection means includes a sensor for measuring a physical quantity required for calculating a capacitance value of said correction electronic element. 8. The ultrasonic motor according to claim 1, wherein said connection means is provided integrally with said support plate. 9. An electronic apparatus comprising the ultrasonic motor according to claim 1.