JPH06109481A - Code disk mounting position adjusting device - Google Patents

Abstract

PURPOSE:To move a code disk to a target direction accurately by obtaining the eccentricity vector of the center of the code disk for the center of a shaft and then compensating the eccentricity based on it. CONSTITUTION:A shaft 2 is rotated by one revolution and a computer 20 obtains the eccentricity state of the center of a code disk 1 for the center of the shaft 2 as vector information from the output waveform of a light reception element 6 at this time. When the eccentricity vector is determined, the computer 20 calculates the amount of travel of an X-Y stage corresponding to it and then gives the amount of travel needed for actuators 15 and 16. Each actuator moves the code disk 1 in a specific direction based on the data and then performs centering. At this time, a rough-move actuator is initially operated and further a fine-move actuator is operated for a fine adjustment in micron order. In this manner, the shaft 2 may be rotated by one revolution and each actuator performs positioning in one piece with the code disk 1, thus moving the code disk 1 accurately in the target direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for adjusting a mounting position of a circular code plate used as an angle detecting portion of a rotary encoder, and more particularly, to improvement of center position alignment with respect to a shaft.

[0002]

2. Description of the Related Art As an angle detecting portion of a rotary encoder, a code plate provided with a large number of slits at equal intervals along a circumferential direction as shown in FIG.

By the way, when attaching such a code plate to the shaft, the center of the code plate must be aligned with the center of the shaft. FIG. 5 shows a schematic configuration of a conventional cord plate mounting position adjusting device. In the figure, 1
Is a code plate and is attached to the shaft 2.
The shaft 2 is rotatably supported by a body 4 via a bearing 3. Reference numeral 5 is a light emitting element, and 6 is a light receiving element. The light emitting element 5 and the light receiving element 6 are arranged facing each other on both sides of the code plate 1 so as to function as an optical sensor for optically detecting the band-shaped slit of the code plate 1. ing. Reference numeral 7 denotes an actuator that selectively presses the outer circumference of the code plate 1, and is arranged on a straight line passing through the center of the shaft 2 and the optical sensor.

In such a structure, the output of the light receiving element 6 when the shaft 2 is rotated is recorded. here,
If the center of the code plate 1 and the center of the shaft 2 are aligned without eccentricity, the output becomes constant, but if the center of the code plate 1 and the center of the shaft 2 are eccentric, the output becomes sinusoidal. Therefore, the eccentricity can be eliminated by adjusting the attachment position of the cord plate 1 by the actuator 7 so that the sine wave signal output becomes zero. Specifically, since the amplitude of the sinusoidal signal output is proportional to the magnitude of the eccentricity, the detection sensitivity of the optical sensor (output per unit distance, for example, mV /
By previously obtaining (μm), the amount of eccentricity can be obtained from the amplitude of the sinusoidal signal output. Since the eccentric direction is the position of the shaft 2 where the maximum amplitude is generated, the code plate 1 may be moved by the actuator 7 by the eccentric amount obtained from the amplitude of the sinusoidal signal output at that position.

[0005]

However, with such a conventional configuration, it is difficult to move the code plate 1 in the correct direction accurately even if the code plate 1 is moved with an accuracy of the order of microns, and the position adjustment is repeated many times. It is the current situation that the above is repeated to converge to the desired mounting positional relationship.

The cause is that the code plate 1 has a slight difference in static friction coefficient between the contact surfaces of the code plate 1 and the shaft 2.
It is conceivable that it will shift in an oblique direction different from the direction in which was pressed. If the code plate 1 moves in the wrong direction in this way, the code plate 1 must be rotated again to measure the eccentricity amount and the eccentric direction, and the position adjustment work must be repeated. Shaft 2 is used to adjust these positions.
After measuring the output signal of the optical sensor by rotating the shaft 1 once, the shaft 2 or the optical sensor must be rotated to a position where the actuator 7 pushes the code plate 1, that is, a position where the output signal of the optical sensor is maximized. Since the rotating operation is required twice, it is an obstacle to automated production.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to accurately move a cord plate in a target direction and to prevent a rotational motion during adjustment. It is to provide a code plate attachment position adjusting device that can be turned.

[0008]

A cord plate mounting position adjusting device according to the present invention is provided with a rotatable shaft, a large number of slits in the circumferential direction, and a single band-shaped slit, and is attached to the shaft. Based on the output of the eccentricity detection unit and an eccentricity detection unit that obtains an eccentricity vector of the center of the code plate with respect to the center of the shaft by optically detecting a code plate and a slit provided in a band shape on the code plate. And at least two actuators for moving the code plate from at least two directions orthogonal to each other so as to correct the eccentricity.

[0009]

The eccentricity detecting section obtains the eccentricity state of the center of the code plate with respect to the center of the shaft as vector information by rotating the shaft once.

Each actuator moves the code plate by a predetermined amount from a direction orthogonal to each other based on the eccentricity vector information,
Corrects the eccentricity of the center of the code plate with respect to the center of the shaft with high accuracy.

As a result, the shaft need only be rotated once to obtain the eccentricity vector, and the eccentricity can be corrected in a short time.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a block diagram of an embodiment of the present invention, FIG.
FIG. 3 is a configuration diagram of the actuator section of FIG. 1, parts common to FIG. 5 are designated by the same reference numerals, and re-explanation thereof will be omitted.

In the figure, 10 is an actuator section. The actuator section 10 includes a code plate 11 having a plurality of slits provided at regular intervals in a band shape along the circumferential direction, which constitutes an encoder for detecting the code plate position for determining the rotational position of the code plate 1, and the code plate 11. A shaft holding portion 12 for fixing the actuator portion 10 to the shaft 2 with a plate 11 arranged on the upper portion, and the shaft holding portion 12
The XY stage 13 integrated with the XY stage 1, the code plate 1 provided below the XY stage 13, and the XY stage 1
3 and a code plate suction portion 14 for mechanically fixing them. Then, on the XY stage 13,
Actuators 15 and 16 are provided, which are composed of a motor, precision screws, and piezoelectric elements, and precisely position the XY stage 13 in the X and Y directions, respectively.

Reference numeral 17 denotes a light emitting element, and 18 denotes a light receiving element, which function as an optical sensor which constitutes an encoder for detecting the position of the code plate, and are arranged so as to detect the slit of the code plate 11. There is. Reference numeral 19 is an air source for air-chucking the cord plate suction portion 14 to the cord plate 1. Reference numeral 20 denotes a computer for controlling each unit, which receives the output signals of the light receiving elements 6 and 18 constituting each optical sensor and outputs movement amount data to the actuators 15 and 16.

The operation of the cord plate mounting position adjusting device thus constructed will be described. The actuator 10 is attached to the shaft 2 as follows. In advance, the code plate 11 of the separate rotary encoder is attached to the upper part of the shaft hold portion 12. As the rotary encoder, one having a relatively low resolution of about 500 pulses per rotation is sufficient, and with this, the rotation angle of the shaft 2, that is, the rotation angle of the code plate 1 is quantitatively measured. Further, an XY stage 13 is attached to the lower part of the shaft hold unit 12. As described above, the XY stage 13 is provided with actuators 15 and 16 that are configured by the motor, the precision screw, and the piezoelectric element as described above, and that precisely position the XY stage 13 in the X direction and the Y direction. Has been. These actuators 1
The motors 5 and 16 and precision screws perform coarse position adjustment, and the piezoelectric elements perform precision position adjustment. Further, a code plate suction portion 14 that suctions and mechanically fixes the code plate 1 and the XY stage 13 is provided below the XY stage 13.

The shaft holding portion 12 to which these respective components are attached is fitted on the upper portion of the shaft 2 to which the code plate 1 is attached. Then, first, the code plate 1 is fixed to the XY stage 13 by an air chuck, and then the shaft hold portion 12 is fixed to the shaft 2. As a result, the code plate 1 can be moved in any desired direction with a micron-order resolution.

Specifically, the shaft 2 is rotated once by a method similar to the conventional method, and the computer 20 decenters the center of the code plate 1 from the center of the shaft 2 based on the phase and amplitude of the output waveform of the light receiving element 6 at this time. Obtain the state as vector information. The output signal of the light receiving element 18 is used for the eccentric direction. By determining the eccentricity vector to move the code plate 1, the corresponding movement amount of the XY stage 13 can be calculated, and the computer 20 gives the calculation results of the required movement amount data to the actuators 15 and 16. Each of the actuators 15 and 16 moves the code plate 1 in a predetermined direction based on the movement amount data to perform centering. At this time, the coarse actuator is operated up to 10 μm, and thereafter the fine actuator is used for fine adjustment on the order of micron. As described above, by providing the coarse movement and the fine movement, fine adjustment is possible even if the initial mounting accuracy of the cord plate is largely deviated from the center.

As is clear from the above description, the shaft 2 may be rotated once in order to calculate the eccentricity vector, and the actuators 15 and 16 are integrated with the code plate 1 to perform positioning. The plate 1 can be accurately moved in the target direction.

FIG. 3 is a block diagram of another embodiment of the present invention. In FIG. 3, four actuators similar to those in FIG.
They are provided around the shaft 2 at intervals. This allows
Even if the code plate 1 moves in an oblique direction according to the driving force of one actuator, it can be immediately corrected by the driving forces of the other three actuators.

[0020]

According to the present invention described above, it is possible to provide a cord plate mounting position adjusting device which can accurately move a cord plate in a target direction and can perform one rotation operation at the time of adjustment.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of an actuator unit in FIG.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a configuration diagram of an example of a code plate.

FIG. 5 is a schematic configuration diagram of a conventional cord plate attachment position adjusting device.

[Explanation of symbols]

 1, 11 Code plate 2 Shaft 3 Bearing 4 Body 5,17 Light emitting element 6,18 Light receiving element 12 Shaft hold part 13 XY stage 14 Code plate suction part 15 X direction actuator 16 Y direction actuator 19 Air source 20 Computer

Claims (1)

[Claims] 1. A rotatable shaft, a plurality of slits in the circumferential direction, a cord plate provided with one strip-shaped slit and attached to the shaft, and a slit provided in the cord plate in a strip shape. An eccentricity detection unit that obtains an eccentricity vector of the center of the code plate with respect to the center of the shaft by optical detection, and moves the code plate from at least two orthogonal directions so as to correct the eccentricity based on the output of the eccentricity detection unit. A cord plate mounting position adjusting device comprising at least two actuators.