JPH06284785A - Positioning table apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to minimize the decrease in torque during phase switching. [Structure] A table top plate 1 is attached to a guide 2 so as to sandwich a linear motor coil 4 via a guide portion 12, and the table top plate 1 is guided by a guide 2 so as to be slidable in the coil arrangement direction. To be done. A position detector 6 for detecting the position of the table top 1 is provided on the side of the guide 2. The position detector 6 is connected with a counter unit 7 for obtaining a position signal of the table, and the counter unit 7 is connected with a phase switching controller 9 for switching each coil phase. The phase switching controller 9 is connected with a time measuring means 13 for measuring the time after the energization of the next coil phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning table device used for a machine tool, a semiconductor exposure apparatus, etc., and more particularly to a position detector for detecting the position of the table and a coil selectively energized according to the position of the table. The present invention relates to a positioning table device having a multi-phase type motor.

[0002]

2. Description of the Related Art FIG. 6 is a schematic configuration diagram of a conventional positioning table device. The conventional positioning table device as shown in this figure includes a linear motor coil 104 in which four-phase coils are arranged in a straight line. The linear motor coil 104 is supported by the coil support member 103, and a pair of guides 102 are provided in parallel with the direction in which the coils forming the linear motor coil 104 are arranged. A pair of upper and lower table tops 101 are provided on the guides 11 as guide portions 11.
The linear motor coil 104 is mounted so as to sandwich the linear motor coil 104, and the pair of upper and lower table top plates 1 are slidably guided by guides 102 in the direction in which the coils are arranged. As the guide portion 112, rolling, sliding, static pressure guide or the like is used in consideration of positioning accuracy and maintainability. A movable magnet 105 is attached to each of the pair of upper and lower table tops 101, and the movable magnet 105 is formed by arranging four permanent magnets with alternating polarities in the direction in which the coils are arranged. The movable magnets 105 are attached to the table top plate 101 via the linear motor coils 104 so as to face each other with different polarities.

A position detector 106 such as a linear scale for detecting the position of the table top 101 is provided on the side of the guide 102. The position detector 106 is connected to a counter unit 107 for obtaining a position signal of the table, and the counter unit 107 is connected to a phase switching controller 109 for switching each coil phase. The phase switching controller 109 controls switching of the switch 110 according to the position signal of the table from the counter unit 107. Each switch 11
For each 0, the coil phase is connected via the current amplifier 111, and the phase switching controller 109 controls the switching of the switch 110 to switch the energization to each coil. Further, the counter unit 107 is connected to a servo controller 108 that calculates a difference between the target position of the table and the current position obtained from the counter unit 107 and outputs the difference to each switch 10 as a command value.

Here, the energization pattern of the linear motor coil in the conventional positioning table device is shown. FIG. 7 is a diagram showing an energization pattern of a linear motor coil provided in a conventional positioning table device. In the figure, four coils forming the linear motor coil are referred to as coils 1 to 4 from the left in the figure for convenience. The symbol A
Symbols B and B indicate the directions of the currents flowing in the coils, symbol A indicates the direction of the currents facing backward when viewed from the front of the drawing, and symbol B indicates the currents that face toward the front when viewed from the front of the drawing.

As shown in FIGS. 7 (a) to 7 (h), the direction of the coil to be energized and the current flowing through the coil are switched depending on the position of the movable magnet 105, and thrust is generated in the same direction, whereby the movable magnet 105 is generated. Is moved in a predetermined direction and the table is moved.

[0006]

However, the above-mentioned conventional example has a problem that the torque is reduced to near zero at the time of switching because of the control configuration in which the coils are switched phase by phase at a predetermined position. It was

FIG. 8 is a diagram showing a state of torque when the coil 1 is switched to the coil 2. As shown in (a) of this figure, for example, when the coil 1 is switched to the coil 2, it takes time ΔT to rise the current of the coil 2, so that as shown in (b) of FIG. Will fall.

Problems when such a reduction in torque (phase switching) occurs near the target position will be described below. FIG. 9 is a graph showing a case where there is no torque decrease near the target position, and FIG. 10 is a graph when there is a torque decrease (phase switching) near the target position.

As compared with the graph shown in FIG. 9 in the case where there is no decrease in torque, in the graph shown in FIG. 10, when there is a decrease in torque, the followability (servo characteristic) of the target value deteriorates. Therefore, it can be seen that the position of the table is oscillating. For this reason, the decrease in torque is not preferable because it causes a decrease in positioning accuracy, an increase in positioning time, and the like, which adversely affects the control system.

The present invention has been made in view of the above problems in the prior art, and an object of the present invention is to provide a positioning table device capable of suppressing a decrease in torque at the time of phase switching as much as possible.

[0011]

SUMMARY OF THE INVENTION To achieve the above object, the present invention is directed to a position detecting means for detecting the position of a table, and a number of coils selectively energized according to the position of the table. A positioning table device provided with a phase type motor, characterized in that it is provided with a time measuring means for measuring the time from when the next coil is energized, and a predetermined time measured by the time measuring means. The device may be one in which (N + 1) or more coils are energized during the time, and the device may be characterized in that the predetermined time is proportional to the current rising time of the coil energized next.

[0012]

As described above, according to the present invention, when the table is moved while sequentially switching the coils on the basis of the predetermined energization pattern, the time from the time when the next coil is energized is measured by the time measuring means. By not energizing the previous coil during the measurement time,
It becomes possible to suppress the decrease in torque at the time of switching as in the conventional case as much as possible.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic configuration diagram of a first embodiment of a positioning table device according to the present invention. The positioning table device of the present invention as shown in this figure includes a linear motor coil 4 in which four-phase coils are arranged in a straight line as in the prior art. The linear motor coil 4 is supported by the coil supporting member 3, and the linear motor coil 4 is
Of the pair of guides 2 parallel to the direction in which the coils forming the
Is provided. A pair of upper and lower table tops 1 are attached to the guide 2 so as to sandwich the linear motor coil 4 via a guide portion 12, and the pair of upper and lower table tops 1 are slid by the guide 2 in the direction in which the coils are arranged. Guided freely. As the guide portion 12, rolling, sliding, static pressure guide or the like is used in consideration of positioning accuracy and maintainability. A movable magnet 5 is attached to each of the pair of upper and lower table tops 1. The movable magnet 5 is formed by arranging four permanent magnets with alternating polarities in the direction in which the coils are arranged. And each movable magnet 5 is a linear motor coil 4
Are attached to the table top plate 1 so that polarities different from each other face each other.

A position detector 6 such as a linear scale for detecting the position of the table top 1 is provided on the side of the guide 2. The position detector 6 is connected with a counter unit 7 for obtaining a position signal of the table, and the counter unit 7 is connected with a phase switching controller 9 for switching each coil phase. Phase switching controller 9
Is for switching and controlling the switch 10 in accordance with the position signal of the table from the counter unit 7. A coil phase is connected to each switch 10 via a current amplifier 11, and the phase switching controller 9 controls switching of the switch 10 to switch energization to each coil phase. Further, the counter unit 7 is connected to a servo controller 8 that calculates a difference between the target position of the table and the current position obtained from the counter unit 7 and outputs the difference to each switch 10 as a command value.

The phase switching controller 9 is connected to a time measuring means 13, which is a feature of the present invention, for measuring the time from the moment when power is turned on to the next coil phase, and the time measuring means 13 is a counter. A circuit timer is possible. That is, the counter unit 7
When it is found from the table position signal obtained from the table that the table has reached the target position and the phase switching controller 9 energizes the next coil phase, the time measuring means 13 is activated at the same time. Thus, it is possible to delay the energization OFF of the previous coil phase at the time preset in the time measuring means 13.

From the above, the energization pattern in the positioning table device of the present invention is as shown in FIG. FIG. 2 is a diagram showing the movement locus of the movable magnet according to the energization pattern of the positioning table device of the present invention.

As shown in (a) to (h) of FIG. 2, during the conventional sequence of switching the coils one by one, the time measuring means described above turns on the two-phase coils for a predetermined time. A sequence is added.

The state of torque when the time measuring means is used during phase switching will be described with reference to FIG. FIG. 3 is a graph showing the state of torque during phase switching in the first embodiment of the table positioning device of the present invention.

As shown in FIG. 3A, when the coil 1 is switched to the coil 2, the coil 2 is energized.
At that time, the time measuring means is operated to energize the coil 1 while the coil 2 takes time ΔT to rise the current.
The FF can be delayed by the time Δt. For this reason,
As shown in FIG. 3B, the decrease in the combined torque can be suppressed as small as possible compared with the conventional case. Further, the time Δt for this purpose needs to be optimally adjusted (proportional) according to the current rising time ΔT of the coil.

(Second Embodiment) FIG. 4 is a schematic structural view of a second embodiment of the positioning table device of the present invention. Since the device of this embodiment is almost the same as the device configuration shown in the first embodiment, a configuration different from that of the first embodiment will be described in this embodiment.

In the positioning table device of the present invention, a magnetic or optical position detecting element 14 may be arranged separately from the position detector 6 for phase switching.

For example, as shown in FIG. 4, Hall elements 14 capable of detecting a magnetic field are arranged at the central portions of the coils constituting the linear motor coil 4 provided in the apparatus of the present invention. Each Hall element 14 is connected to the phase switching controller 9, and when a magnetic field for the Hall element 14 is applied by the movable magnet 5, the Hall element 1
Reference numeral 4 faithfully detects the position of the magnetic pole of the movable magnet 5, converts it into an electric signal, and outputs this electric signal to the phase switching controller 9. As a result, the phase switching controller 9 can sequentially turn on the coil phases according to the position of the table, as in the first embodiment.

The phase switching controller 9 is connected to a time measuring means 13, which is a feature of the present invention, for measuring the time from the moment when power is turned on to the next coil phase, and the time measuring means 13 is a counter. A circuit timer is possible. That is, when it is found from the table position signal obtained from the Hall element 14 that the target position has been reached, and the energization of the next coil phase is turned on by the phase switching controller 9, the time measuring means 13 is activated at the same time. As a result, it is possible to delay the energization OFF of the previous coil phase at the time preset in the time measuring means 13.

Therefore, also in the present embodiment, the decrease in torque can be suppressed as small as possible compared with the conventional case.

In the first and second embodiments described above, an optical or magnetic linear scale is used as the position detector 6, but in a highly accurate positioning table device such as a semiconductor exposure device, it has a high resolution. It is more preferable to use a different laser length measuring device.

In addition, in the first and second embodiments, normally 1
Although a case has been shown where two coils are energized and two coils are energized at the time of phase switching, depending on the configuration of the linear motor coil, normally N coils are energized and at the time of phase switching (N
It is of course possible to energize +1) or more coils.

Further, the present invention can be applied to a rotary type stage device having a circular multiphase motor coil as shown in FIG. FIG. 5 is a perspective view of the rotary stage device. Even in the stage in which the movable magnet 16 is arranged below the rotary table top 15 as shown in this figure, and which rotates on the divided motor coil 17 according to the position signal obtained from the position detector 18, the present invention can be used. The time measuring means can be similarly applied.

[0029]

According to the present invention as described above, the time measuring means is provided to suppress the decrease of the torque at the time of switching, so that the positioning accuracy, the positioning time, etc. and the control system are not adversely affected. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a positioning table device according to the present invention.

FIG. 2 is a diagram showing a moving locus of a movable magnet according to an energization pattern of a positioning table device of the present invention.

FIG. 3 is a graph showing a torque state during phase switching in the first embodiment of the table positioning device of the present invention.

FIG. 4 is a schematic configuration diagram of a second embodiment of the positioning table device of the present invention.

FIG. 5 is a perspective view of a rotary stage device.

FIG. 6 is a schematic configuration diagram of a conventional positioning table device.

FIG. 7 is a diagram showing an energization pattern of a linear motor coil provided in a conventional positioning table device.

FIG. 8 is a diagram showing a torque state when the coil 1 is switched to the coil 2.

FIG. 9 is a graph showing a case where there is no decrease in torque near the target position.

FIG. 10 is a graph when there is a decrease in torque (phase switching) near the target position.

[Explanation of symbols]

 1 table top plate 2 guide 3 coil support member 4 linear motor coil 5, 16 movable magnet 6 servo controller 7 counter unit 8 servo controller 9 phase switching controller 10 switch 11 current amplifier 12 guide section 13 time measuring means 14 hall element 15 rotary table Top plate 17 Motor coil 18 Position detector (rotary encoder)

Claims (3)

[Claims] 1. A positioning table device comprising position detecting means for detecting the position of a table, and a polyphase motor for selectively energizing N coils according to the position of the table, comprising: A positioning table device provided with a time measuring means for measuring a time from when the coil is energized. 2. The positioning table device according to claim 1, wherein (N + 1) or more coils are energized during a predetermined time measured by the time measuring means. 3. The positioning table device according to claim 2, wherein the predetermined time is proportional to a current rising time of a coil which is energized next time.