JPS63237831A - Positioning device for xy table - Google Patents

Abstract

PURPOSE:To promote the improvement of positioning accuracy of an XY table, by mounting one of the linear scale, which forms a position detector, and the detecting head to the side surface of a yoke and the other to a stage. CONSTITUTION:Position detectors 20', 20 in y-axis and x-axis directions, mounting respectively to their side surface a detecting head 22 and a linear scale 21, are constituted between a stage 7 and an X-axis yoke 3 and between the stage 7 and a Y-axis yoke 3. Now a threaded shaft 12 is rotated by a motor 11, and if the Y-axis yoke 3 is moved in the y-axis direction, the stage 7 moves in the y-axis direction along a guide hole 6 of the X-axis yoke 2 and stops if the position detector 20' reads its measurement value agreeing with the instruction value. Here yawing action is generated in a linear bearing 5, and if a movement theta is generated in the Y-axis yoke 3, an error e0 is generated between the y-axis direction position detector 20' and the center of the stage 7, but this value, obtaining a difference between the conventional error e1 and a measured value e2, provides a less error. In this way, the stage can be high accurately positioned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning device for an XY table used for moving a workpiece to an arbitrary position on a plane.

[Prior art and its problems] As a prior art of the above-mentioned XY table, there is one shown in FIG. This XY table has an X-axis yoke 2 and a Y-axis yoke 3 arranged orthogonally on the upper surface of a pedestal 1, and both ends of each yoke 2.3 are supported by a pair of parallel linear bearings 4.5. It supports the X-axis yoke 2 and the Y-axis yoke 3 so as to be movable in orthogonal directions.

In addition, a long guide hole 6 is formed in each of the X-axis yoke 2 and the Y-axis yoke 3 in a direction perpendicular to the moving direction of each yoke 2.3, and a stage 7 arranged at the intersection of the guide holes 6 is placed in each It supports movably along the guide hole 6.

Further, the X-wheel yoke 2 and the Y-axis yoke 3 are moved by an X-axis moving device 10 and a y-axis moving device 10', respectively.

Here, the X-axis moving device 10 and the y-axis moving device 10' consist of a screw shaft 12 rotated by a motor 11 and a NAND 13 screwed into this screw shaft 12. It is rotatably supported by a bearing 14 mounted on the top surface, while a nut 13 is fixed to the bottom surface of each yoke 2.3.

Therefore, the motor 11 is driven to rotate the screw shaft 12,
When the X-axis yoke 2 is moved along the parallel linear bearing 4, the stage 7 is moved along the guide hole 6 of the Y-axis cork 3 in the X-axis direction (horizontal direction in FIG. 3), and the Y-axis yoke 3
When the stage 7 is moved, the stage 7 moves in the y-axis direction (vertical direction in FIG. 3) along the guide hole 6 of the X-axis yoke 2.

In such an XY table, since high positioning accuracy is required for the stage 7, position detectors 20 and 20' are usually provided to detect the position of the stage 7 in the X-axis direction and the y-axis direction. The measured values of the detectors 20 and 20' are used to control the motor 11 of the X-axis moving device 10 and the motor 11 of the Y-axis moving device 10'. Control each motor 11 by giving feedback to each section 711? ■I try to do that.

By the way, in the conventional XY table, the linear scale 21 forming the position detector 20.20' is disposed between the linear bearing 4.5 and the screw shaft 12 and supported by the pedestal 1.
Since the detection head 22 is attached to the end faces of the X-axis yoke 2 and the Y-axis cork 3, the position detector 20.20'
A large distance is created between the detection position of the stage 7 and the center of the stage 7,
There is a disadvantage that the positioning accuracy of the stage 7 is poor.

That is, in the XY table, each of the X-axis yoke 2 and the Y-axis yoke 3 is supported by a linear bearing 4.5, so when each yoke 2.3 moves, the linear bearing 4
．． 5, and if the yawing causes the y-axis yoke 3 to tilt by an angle θ, for example,
An error corresponding to e occurs between the detected position of the position detector 20' and the center of the stage 7. In the case of feedback control, when the command value input to the control section of the motor of the moving device matches the measured value fed back to the control section from the position detector 20', positioning is completed. A positional shift occurs at 01 at the stop position.

[Purpose of the invention]

Therefore, it is an object of the present invention to eliminate the above-mentioned disadvantages and improve the positioning accuracy of the XY table.

[Structure of the invention]

In order to achieve the above object, the present invention has a configuration in which one of the linear scale and the detection head forming the position detector is attached to the side of the yoke, and the other is attached to the stage.

(Function) With the above configuration, the position detector is placed close to the center of the stage inside the linear bearing that guides the movement of the yoke, so even if yawing occurs in the linear bearing, the position can be detected. The error occurring between the detected position of the device and the center of the stage is small, and as a result, the stage can be positioned with extremely high accuracy.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

Note that the same parts as in the conventional example shown in FIG. 3 described above are given the same reference numerals, and the explanation thereof will be omitted.

As shown in the figure, the stage 7 includes a plurality of guide rollers 8 that can contact the side surfaces of the guide holes 6 in the X-axis yoke 2 and the Y-axis yoke 3, and is provided between the stage 7 and the X-axis yoke 2. , a position detector 20' for detecting the position of the stage 7 in the y-axis direction is provided. Further, a position detector 20 is provided between the stage 7 and the Y-axis yoke 3 to detect the position of the stage 7 in the X-axis direction.

The position detector 20 in the X-axis direction and the position detector 20' in the y-axis direction are composed of a linear scale 21 and a detection head 22, and the linear scale 21 is attached to the side surface of the X-axis yoke 2 and the Y-axis yoke 3. , while the detection head 22 is
It is attached to the side of stage 7.

Note that the linear scale 21 may be attached to the stage 7 and the detection rod 22 may be attached to the X-axis yoke 2 and the Y-axis yoke 3.

Now, when the motor 11 is driven to rotate the screw shaft 12 and move the Y-axis yoke 3 in the y-axis direction, the stage 7 moves in the y-axis direction along the guide hole 6 of the X-axis yoke 2. The amount of movement is detected by the position detector 20' in the y-axis direction, and the measured value is fed back to the control section of the motor 11 in the y-axis moving device 10', and is combined with the command value input in advance to the control section. If they match, the motor 11 will stop.

In controlling the position of the stage 7 as described above, yawing occurs in the linear bearing 5 that guides the movement of the Y-axis yoke 3, and the Y-axis yoke 3 whose position is controlled has an angle θ as in the case of FIG. When peeling occurs around 1, an error of 00 occurs between the position detector 20 in the y-axis direction and the center of the stage 7.

This error, e, is, e.

= Q, -eg, so the value is smaller than el and the third
The error is smaller compared to the conventional XY table shown in the figure.
As a result, the stage 7 can be controlled with extremely high precision.

〔effect〕

As described above, according to the present invention, the position detector is installed between the stage and the two yokes that support the stage, and the position detector is placed inside the linear bearing that guides the movement of the yoke. , the position detector is mounted close to the center of the stage, and as a result, even if yawing occurs in the linear bearings that guide the movement of each yoke, the position error is extremely small and the stage can be positioned with extremely high precision. can.

[Brief explanation of drawings]

FIG. 1 is a plan view of a positioning device according to the present invention, and FIG.
The figure is a longitudinal sectional front view of the same as the above, and FIG. 3 is a plan view showing a conventional positioning device. 2...X-axis yoke, 3...Y-axis yoke, 4.5...linear bearing, 6...guide hole, 7...・Stage, 10...X-axis moving device, 10'...y-axis moving device, 20.20
'...Position detector, 21...Linear scale, 22...Detection head.

Claims (1)

[Claims] Equipped with two yokes movable in the directions of two orthogonal axes, a stage movable along guides formed on each yoke is placed at the intersection of the guides, and the position of the stage is detected by a position detector. In the positioning device for the XY table, which detects the position by the position detector and feeds back the measured value of the position detector to the control unit of the yoke moving device, one of the linear scale and the detection head forming the position detector is attached to the side of the yoke. X characterized in that the other side is attached to the stage
Y table positioning device.