JP4391257B2 - Ultrasonic motor position detector - Google Patents

Description

  The present invention relates to a position detection device that detects the rotational position of a rotor of an ultrasonic motor.

As a motor control method, a method of detecting the rotational position of the rotor and performing feedback control of the rotor based on the detected information is generally used. Various types of position detection devices for detecting the position of the rotor are known depending on the type of motor and use conditions. A so-called encoder and a device using a PSD as a position detecting element as disclosed in Patent Document 1 are known. In recent years, as disclosed in Patent Documents 2 to 5, for example, position detection devices used for ultrasonic motors have also been proposed.
JP-A-6-18285 JP-A-5-45150 JP-A-5-276767 JP 2000-78864 A JP 2002-156248 A

  Now, there is a demand for a motor position detection device that is smaller and has high detection accuracy, and for devices that are used in ultrasonic motors, further ingenuity is required to meet such demands. In particular, the ultrasonic motor rotates the rotor by bringing the rotor into close contact with a vibrating body mounted on a piezoelectric element such as ceramic and transmitting the elastic vibration of the piezoelectric element to the rotor via the vibrating body. Since the vibration frequency is 20 kHz or more, it is difficult to control by counting the number of pulses applied to the piezoelectric element. Another problem is that the rotor is displaced with respect to the number of pulses. This invention is made | formed in view of this situation, The objective is to provide the position detection apparatus of the more superior ultrasonic motor.

The invention described in claim 1 of the present application is a position detection device for detecting the rotational position of a rotor of an ultrasonic motor , wherein the ultrasonic motor constitutes a driving unit for an instrument, and vibrates a piezoelectric element. A rotor rotates on the outer periphery of a stator with a body mounted thereon, and the instrument drive unit displays a predetermined count according to an angle of a needle mounted on the rotor. Is formed by fixing a metal plate of a predetermined shape in close contact with the vibrating body to a pipe-shaped rotating shaft, and is rotatably supported by a case body via a bearing. When elastic vibration of the piezoelectric element is transmitted, the piezoelectric element and the vibrating body rotate around the rotating shaft portion, and the piezoelectric element and the vibrating body pass through the rotating shaft portion and support the base end portion of the case body. Fixed to And, the position detecting apparatus, and a link mechanism for converting rotary motion into linear motion of the rotor, and a link member for a linear movement by said link mechanism, and a translucent portion provided on said link member, said link A light guide disposed to face one side of the body, a light source for injecting light into the light guide, a position detection element disposed to face the other side of the link, A signal processing circuit for processing the output of the position detection element to identify the position of the rotor, spot light is irradiated from the light guide to the light receiving surface of the position detection element through the light transmitting portion, and the rotor rack There are those wherein the rotating spot light moves on the light receiving surface of the position detecting device, the link mechanism is provided with a gear at the tip of the rotation shaft, for the gear and meshed with said link member Was constructed by providing the link member is slidably held in strategic points in the case body, when the rotor rotates, the configuration which is adapted to move linearly in a direction perpendicular to the rotation shaft Ultra It is a position detection device of a sonic motor.

  According to the present invention, a more excellent ultrasonic motor position detection device can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. A motor apparatus 1 shown in FIGS. 1 to 5 is a driving unit for an instrument, and is used, for example, in a speedometer of an automobile. The motor device 1 includes an ultrasonic motor 100, a position detection device 200 that detects the rotational position of the rotor 110 of the ultrasonic motor 100, a control circuit 300 that controls the ultrasonic motor 100, and a case body 2 that holds them. And a predetermined count display is made according to the angle of the needle 3 attached to the rotor 110.

  The ultrasonic motor 100 is configured such that the rotor 110 rotates on the outer periphery of a stator 120 formed by mounting a vibrating body 122 on a piezoelectric element 121. The rotor 110 is formed by fixing a metal plate 111 having a predetermined shape in close contact with the vibrating body 122 to a pipe-shaped rotating shaft portion 112 with a metal ring 113. The rotor 110 is rotatably supported by the case body 2 via the bearing 4. When the elastic vibration of the piezoelectric element 121 is transmitted from the vibrating body 122, the rotor 110 rotates around the rotation shaft portion 112. Further, the piezoelectric element 121 and the vibrating body 122 are fixed to a support body 123 that passes through the rotating shaft portion 112 and supports the base end portion 123a of the case body 2 (see FIG. 2). That is, the stator 120 is fixed to the case body 2. The piezoelectric element 121 is wired with the control circuit 300. The control circuit 300 controls the excitation of the piezoelectric element 121 according to the rotational position of the rotor 110 detected by the position detection device 200, thereby rotating the rotor 110 toward the target position. That is, the rotor 110 is feedback controlled based on the detection information of the position detection device 200.

  The position detection device 200 of the present example includes a link mechanism that converts the rotational motion of the rotor 110 into a linear motion, a link body 210 that performs a linear motion by the link mechanism, a light transmitting portion 212 provided in the link body 210, a link Light guide 220 arranged to face one side of body 210, light source 230 for injecting light into light guide 220, and position detection arranged to face the other side of link body 210 An element (hereinafter referred to as PSD) 240 and a signal processing circuit 320 that processes the output of the PSD 240 and identifies the position of the rotor 110 are provided.

  The link mechanism is configured such that a gear 114 is fixed to the tip of the rotating shaft portion 112 of the rotor 110 and a rack portion 211 that meshes with the gear 114 is provided on the link body 210. The link body 210 is slidably held at the main part of the case body 2, and linearly moves in a direction orthogonal to the rotation shaft portion 112 of the rotor 110 when the rotor 110 rotates. The arrows in the figure indicate the moving directions of the link body 210 corresponding to the rotation directions CW and CCW of the rotor, respectively.

  The light guide 220 is a resin-made transparent member, and a fine concavity and convexity for diffusing light from the light source 230 to the outside is provided on the surface facing the link body 210. The light guide 220 is fixedly provided at a main point of the case body 2. Further, the light source 230 of this example is a light emitting diode provided at a key point of the case body 2.

  The PSD 240 is a spot light position sensor that uses the surface resistance of a photodiode. In this example, the PSD 240 is disposed so that the band-shaped light receiving surface is parallel to the moving direction of the link body 210. The light receiving surface of the PSD 240 is irradiated with spot light from the light guide 220 through the light transmitting part 212. The translucent part 212 is a small hole provided at a key point of the link body 210. When the rotor 110 rotates, the spot light moves on the light receiving surface of the PSD 240. The PSD 240 outputs a current having a value corresponding to the position of the spot light as the position signal of the spot light.

  The signal processing circuit 320 is incorporated in the control circuit 300. The control circuit 300 is configured such that the motor control circuit 310 controls the ultrasonic motor 100 in accordance with the position of the rotor 110 specified by the signal processing circuit 320. The signal processing circuit 320 converts the current output from the PSD 240 into a voltage by an input circuit 321 composed of a resistor or the like and amplifies it, further converts it into a digital signal by the A / D converter 322, and the digital signal is converted into an arithmetic unit 323. This is used as detection information for the position of the rotor 110.

  As described above, according to this example, it is possible to obtain a superior position detecting apparatus for an ultrasonic motor that is smaller and has high detection accuracy. In addition, it is needless to say that the configuration of each part in this example can be appropriately changed in design within the technical scope described in the claims, and is not limited to the illustrated example.

  The position detection device of the present invention can be suitably used in a motor device that uses an ultrasonic motor and feedback-controls the rotor.

It is explanatory drawing which concerns on the Example of this invention and shows the front inside of a motor apparatus. It is explanatory drawing which concerns on the Example of this invention and shows the side surface inside of a motor apparatus. It is explanatory drawing which concerns on the Example of this invention and shows the front of a rotor and a link body. It is explanatory drawing which concerns on the Example of this invention and shows the upper surface of a link body, a light guide, a light source, and PSD. It is explanatory drawing which shows PSD and a signal processing circuit concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor apparatus 2 Case body 3 Needle 4 Bearing 100 Ultrasonic motor 110 Rotor 111 Metal plate 112 Rotating shaft part 113 Metal ring 114 Gear 120 Stator 121 Piezoelectric element 122 Vibrating body 123 Support body 123a Base end part 200 of a support body Position detection apparatus 210 Link body 211 Rack section 212 Light transmission section 220 Light guide body 230 Light source 240 PSD
DESCRIPTION OF SYMBOLS 300 Control circuit 310 Motor control circuit 320 Signal processing circuit 321 Input circuit 322 A / D converter 323 Arithmetic unit

Claims (1)

In the position detection device that detects the rotational position of the rotor of the ultrasonic motor,
The ultrasonic motor constitutes a driving unit for an instrument, and a rotor rotates on the outer periphery of a stator formed by mounting a vibrating body on a piezoelectric element.
The instrument drive unit is a predetermined counting display according to the angle of the needle mounted on the rotor,
The rotor is formed by fixing a metal plate having a predetermined shape in close contact with the vibrating body to a pipe-shaped rotating shaft portion, and is rotatably supported by a case body via a bearing. When elastic vibration of the piezoelectric element is transmitted from the body, it rotates around the rotating shaft part,
The piezoelectric element and the vibrating body are fixed to a support that passes through the rotating shaft and supports the base end of the case body.
The position detection device includes a link mechanism that converts the rotational motion of the rotor into a linear motion, a link body that performs a linear motion by the link mechanism, a translucent portion provided in the link body, and one of the link bodies A light guide disposed to face the side surface of the light source, a light source for injecting light into the light guide, a position detection element disposed to face the other side surface of the link body, and the position detection A signal processing circuit that processes the output of the element and identifies the position of the rotor, and when the spot light is irradiated from the light guide through the light transmitting portion to the light receiving surface of the position detection element, the rotor rotates. The spot light moves on the light receiving surface of the position detecting element;
The link mechanism is configured by providing a gear at the tip of the rotary shaft portion and providing a rack portion meshing with the gear in the link body,
The link body is slidably held at an important part of the case body, and when the rotor rotates, the link body linearly moves in a direction orthogonal to the rotation shaft portion . Position detection device.

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