JPH0628506B2 - Non-contact flat type XY table - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-contact flat type XY table suitable for use in dust-proof semiconductors and biotechnology-related factories.

(Prior Art) Conventionally, there is a direct drive type XY table using a linear motor. This type of linear motor is described in, for example, the editor and the publisher "The Institute of Electrical Engineers of Japan", "Linear Motor and Its Applications," 124-
It is described on page 127. This XY table has programs such as (1) table body with built-in drive mode, (2) motor drive power element section (driver section), (3) positioning stop points for X and Y axes, acceleration / deceleration, and sequence. It consists of three parts of the configurable controller.

(Problems to be Solved by the Invention) However, in this type of conventional XY table, the table including the work is separated from the linear motor and supported by a mechanical linear bearing. Therefore, since this mechanical linear bearing portion is provided, dust is generated from this portion and it is unsuitable for use in a clean room for semiconductor manufacturing or biotechnology. Further, in a high vacuum state, there is a problem that the lubricating oil evaporates, polluting the atmosphere and causing the bearing part to burn.
It was not sufficient as a drive source in an atmosphere under such severe conditions.

The present invention eliminates the above-mentioned problems, and the floating of a movable body by a magnetic force is performed by a blocked linear motor magnetic pole, which is a dustless type and a non-contact flat type X driven directly.
It is intended to provide a Y table.

(Means for Solving Problems) In order to solve the above problems, according to the present invention, in a non-contact plane type XY table, (a) each tip has a plurality of teeth aligned in one direction At least 4 installed at intervals of
A pole member having two pole pieces, and a propulsion guide magnetic pole excited by a propulsion guide coil wound on the pole piece, and wound on the core member adjacent to the propulsion guide magnetic pole. It has first and second linear motor magnetic poles that are integrated with a magnetic pole for attraction excited by an attraction coil, and is arranged so that the tooth rows of the first and second linear motor magnetic poles are orthogonal to each other. A fixed body, and (b) a movable body having a plurality of tooth rows facing the tooth rows of the magnetic poles of each of the linear motors and having a constant pitch and aligned in the tooth row direction, respectively (c)
Displacement detecting means for detecting relative displacement between the fixed body and the movable body, and (d) adjusting a gap between the fixed body and the movable body based on a detection value from the displacement detecting means, and A control means for propelling the body in the magnetically levitated state in the X and Y directions is provided.

(Operation) According to the present invention, in the flat XY table, the movable body is held in a non-contact state by the magnetic force of the attraction magnetic pole, and the set of linear motors that propel the movable body by the magnetic force of the propulsion guide magnetic pole. The movable body having the table in which the teeth of the magnetic poles are arranged so as to be orthogonal to each other can move in the XY directions in a non-contact state.

Further, it has a displacement detection means for detecting the displacement state of the movable body having a table, and a control means for performing the attitude control and the movement control of the movable body based on the detected value. Done.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 to 4, reference numeral 1 indicates the front and rear surfaces are opened,
It is a fixed body having a hollow portion, and is composed of a bottom surface portion 1a, side surface portions 1b extending upward from both ends of the bottom surface portion, and an upper surface portion 1c spanning between upper ends of the side surface portions. have. Reference numeral 2 denotes a linear motor magnetic pole provided below the upper surface portion 1c, and two X-axis driving magnetic poles 2a and Y-axis driving magnetic poles 2b are arranged on a diagonal line so as to be adjacent to each other. Reference numeral 3 is a gap detector attached to the bottom surface 1a, and 4 is a movable body having a table which is supported in a non-contact state by the magnetic force of the linear motor magnetic poles 2 and which is driven in the XY directions.
And a side surface portion 4b extending downward from both ends of the table surface.
And a lower surface portion 4c that extends over both ends of the side surface portion, have. The movable body 4 and the fixed body 1 are arranged so as to interlink. Reference numeral 5 denotes a tooth row formed on the upper surface of the lower surface portion 4c of the movable body 4. Further, four linear motor magnetic poles are arranged on the back side of the upper surface 1c of the fixed body 1. These linear motor magnetic poles have core members as shown in FIG.
A suction coil 11 of the movable body 4 is wound around the base of the movable body 4, and a propulsion guide coil 12 is wound around the tip of the movable body 4. That is, the attraction magnetic pole for magnetically attracting the movable body 4 for non-contact support and the magnetic pole for propulsion guide for magnetically propelling the movable body 4 are integrated. For example, it is constructed by stacking ferromagnetic materials such as electromagnetic net plates punched in a concatenated shape having a concave shape, and suction coils 11-1 and 11-2 are provided on the outer periphery of each recess of the core member 10. They are wound so that they have opposite polarities. Each tip of the core member 10 comprises a first pole piece, a second pole piece, a third pole piece, and a fourth pole piece, and each pole piece has a propulsion guide coil 12-1, 12-2, 12-, respectively.
3, 12-4 are wound, the first magnetic pole 13, the second magnetic pole 14, the third magnetic pole
The magnetic pole 15 and the fourth magnetic pole 16 are formed. These magnetic poles 13,
The pitch of the teeth provided on 14, 15, 16 is the same as the pitch of the teeth of the movable body 4, but the pitch of the teeth of the magnetic poles is deviated,
Based on the first magnetic pole 13, the second magnetic pole 14 has a 1/2 pitch, the third magnetic pole 15 has a 1/4 pitch, and the fourth magnetic pole 16 has
Are arranged so as to be displaced relative to the pitch of the teeth of the movable body 4 by 3/4 pitch.

Next, the operation of this linear motor magnetic pole will be described with reference to FIG.

(1) When a current is applied only to the suction coils 11-1 and 11-2 in the direction indicated by the arrow in FIG. 6 (the positive direction), FIG. 6 (a)
As shown in, the magnetomotive force is generated so that the magnetic flux flows.

(2) When a current is applied only to the propulsion guide coils 12-1 and 12-2 that excite the first magnetic pole 13 and the second magnetic pole 14, magnetic flux flows as shown in FIG. 6 (b). Produces a magnetomotive force.
When a current is passed in the negative direction, the direction of magnetomotive force is reversed and the magnetic flux also flows in the opposite direction.

(3) The same applies to the propulsion guide coils 12-3 and 12-4 that excite the third magnetic pole 15 and the fourth magnetic pole 16 as shown in FIG. 6 (c).

Here, a certain constant current Ic is passed through the suction coil 11. That is, the magnetomotive force shown in FIG. 6 (a) is generated to flow the magnetic flux, and at the same time, the propulsion guide coil 12-1,
When a positive current Ia is passed through 12-2, the magnetomotive forces of the current Ic and the current Ia are strengthened in the first magnetic pole 13, while the magnetomotive forces of the current Ic and the current Ia are canceled in the second magnetic pole 14 to move. The body 4 generates a restoring force that stabilizes at the position shown in FIG. 6 (b). That is, an attempt is made to stabilize the position such that the convex portions of the teeth of the first magnetic pole 13 and the convex portions of the teeth of the movable body 4 coincide with each other.

Next, if the current Ia is made zero and the current Ib is made positive, the third
A magnetic flux acts on the magnetic pole 15 to generate a thrust on the movable body 4 so that the movable body 4 is stabilized at the position shown in FIG. 6 (c).
Advances by 1/4 pitch.

Next, if the current Ib is made zero and the current Ia is made negative, the second
Since the magnetomotive force with respect to the magnetic pole 14 is strengthened and the magnetic flux flows, the step advances by 1/4 pitch.

In this way, Ia (positive) → Ib (positive) → Ia (negative) →
Ib (negative), such as propulsion guidance coils 12-1, 12
-2, 12-3, and 12-4 by switching the current, the movable body 4 is stepped every 1/4 pitch.

With such a configuration, non-contact support of the movable body and propulsion of the movable body can be achieved by a compact linear motor magnetic pole, and a conventional mechanical bearing mechanism such as a rolling bearing can be completely abolished.

In the non-contact plane type XY table of this embodiment, two pairs of linear motor magnetic poles thus arranged are arranged on the back side of the upper surface 1c of the fixed body 1 in directions orthogonal to each other.
That is, as is clear from FIG. 1, linear motor magnetic poles are mounted on the diagonals in which the directions of the magnetic pole tooth rows are aligned in the same direction. That is, the first linear motor magnetic pole 2a
Are provided in the lower right and upper left portions and function as X-axis drive. The second linear motor magnetic pole 2b is provided in the lower left and upper right portions and functions for driving the Y axis.

The tooth row 5 of the movable body 4 facing the linear motor magnetic pole is formed so as to be parallel to the first linear motor magnetic pole 2a in the direction in which the magnetic poles are arranged. That is, it is formed in the vertical direction. Further, the tooth row 5 is the second linear motor magnetic pole 2b.
Also, it is formed so as to be parallel to the direction in which the magnetic poles are arranged. That is, it is formed in the lateral direction.

In this manner, the two first linear motor magnetic poles 2a and the second linear motor magnetic poles 2b are diagonally attached, and the tooth rows 5 face each other so that the movable body 4 can be propelled correspondingly.

Next, the operation of the XY table will be described.

The operation of the XY table is performed by the magnetic force of the magnetic poles of the linear motor magnetic poles for propelling and guiding, and in the case of the XY table, the propulsion of the linear motor magnetic poles 2a, 2a, 2b, 2b so that the movable body 4 can be driven in the XY directions. Guide coil
It is performed by distributing the number of changes of the exciting current to 12. For example,
When the movable body 4 is driven in the X direction, the exciting current is changed only in the propulsion guide coil 12 of the first linear motor magnetic poles 2a, 2a. When driving the movable body 4 only in the Y-axis direction, the magnetic pole current is changed only in the propulsion guide coil 12 of the second linear motor magnetic poles 2b, 2b.

Driving in both X and Y directions can be achieved by changing the exciting current the number of times corresponding to the vector component.

Next, the attitude control of the movable body will be described.

FIG. 7 is a schematic configuration diagram of such a control device.

In the figure, 21 is an electronic control device, 21-1 is a CPU (central processing unit), 21-2 is a memory, 21-3 is an input interface, 21-4 is an MDI (manual data input) device, and 21-5 is I. / O interface, 22 is a power supply, and 23 is a drive circuit.

As shown in this figure, the detection value from each gap detector 3 is read into the electronic control unit 21 via the input interface 21-3, and the gap between the movable body 4 and the fixed body 1 is monitored, When the gap changes, the exciting current of the attraction coil 12 of the linear motor magnetic poles 2a and 2b supplied from the drive circuit 23 is adjusted so as to compensate for the change. That is, when the movable body 4 is tilted, the tilt value of the movable body 4 is corrected by comparing the detected value from each gap detector 3 with the reference value of the gap stored in the memory 21-2 of the electronic control unit 21. can do. In this way, the posture of the movable body 4 is normally controlled.

Next, the micro step drive of the movable body will be described.

Here, the micro-step driving is a method of driving two windings of a magnetic pole of a linear motor with a two-phase current having a 90 ° phase shift to drive as a synchronous motor. For example, the propulsion currents Ia and Ib of the movable body 4 are used. The waveform as shown in FIG.

FIG. 9 is a block diagram of a microstep drive system,
In the figure, 31 is a ring counter, 32 and 33 are ROMs, 34 and 35 are D / A converters, and 36 and 37 are drive amplifiers.

As shown in this figure, when the movement command value is input to the ring counter 31, the waveform data stored in the ROMs 32 and 33, that is, the sine and cosine values are read out and the D / A converters 34 and 35 are read. The analog amount is driven via the drive amplifier 36, 37
Is input to and amplified by the propulsion guide coils 12-1 to 12-
Added to 4. In the waveform, the ratio of the A phase and the B phase is determined by the electrical angle position (time), which is output according to the angular electrical angle position to move the movable body 4. If a voltage amplifier is used as the drive amplifier, passive damping can be expected. With this configuration, the movable body can move smoothly and can be positioned at a minute distance.

By the way, since this actuator drives the movable body 4 in a non-contact state, mechanical diping with respect to the movement of the movable body 4 is very small. Therefore, even if the micro step drive is performed, some vibration is accompanied. In order to suppress this vibration, it is configured as follows.

The phases of the plurality of linear motor magnetic poles arranged in the propulsion direction with respect to the teeth of the movable body 4 are shifted from each other by π / 4.
That is, at a certain point in time, in the propulsion guide coil of one of the linear motor magnetic poles 2a, one of the linear motor magnetic poles 2a is generated so that the magnetomotive force shown in FIG. 10 (a) is generated.
The magnetic poles of the linear motor are arranged so as to generate a magnetomotive force as shown in FIG.

In this way, when the position of the magnetic pole of the linear motor that controls propulsion is shifted by π / 4 in terms of electrical angle, the thrust and damping characteristics are made uniform, and smoother driving is possible compared to the case of the in-phase arrangement. It will be possible.

In the above, the case of the micro step drive has been described.
The pattern is as shown. That is, the linear motor magnetic pole I
Is the one-phase excitation, the motor magnetic pole II is the two-layer excitation, and vice versa.

Here, the plus and minus in the table are the polarities of the coil voltage (or current) when driving the stepper byporter.

As described above, damping can be performed by shifting the excitation phase not only in the micro step drive but also in the case of a normal step motor.

Furthermore, even if n × π / 4 (n = 1, 3, 5, 7) is advanced or delayed, the above-described effects can be obtained. That is, when one of the two is two-phase excitation, the other one is preferably one-phase excitation.

Next, the control of the movable body can be performed as follows.

First, the origin position of the movable body 4 is determined by a dog switch or the like, and the movable body 4 is supported in a non-contact manner at this position. That is, the drive circuit 23 is previously attached to the suction coil of the linear motor magnetic pole.
An exciting current is flown through to bring the movable body 4 into a non-contact state.

Next, in the non-contact state, the detection value from each gap detector 3 is input to the electronic control unit 21.
-3, the read value is compared with the reference value (reference air gap value) of each gap detector 3,
The drive circuit 23 adjusts the excitation current value of the suction coil in each magnetic pole of the linear motor through the I / O interface 21-5 so that the deviation becomes zero.

Thus, by performing the feedback control, it is possible to smoothly perform the attitude control of the movable body.

Next, another embodiment of the non-contact type XY table of the present invention will be described.
This will be described with reference to FIGS. 12 and 13.

In the figure, 41 is a base, 42 is a support, 43 is a fixed body, 44a and 44b are linear motor magnetic poles, 45 is a movable body, and a table surface 45a.
And a side surface portion 45b extending downward from both ends of the table surface.
And a bottom plate 45c extending inward from the lower ends of the four corners of the side surface
Consists of. 46 is a gap detector.

As shown in these figures, a fixed body 43 in which linear motor magnetic poles 44a, 44b are fixed to four corners of a base 41 via columns 42
Is provided. On the other hand, in the movable body 45, the movable body 45 having a plurality of tooth rows is provided on the upper surface of the bottom plate 45c so as to face the linear motor magnetic poles 44a and 44b. Further, the gap detector 46 is provided on the base 41, and the movable body 45 and the base 41 are
It is used to detect the gap between them, that is, the gap between the movable body 45 and the fixed body 43, and to control the attitude of the movable body 45. The structure and operation of the other parts are the same as those in the above-described embodiment, and thus the description thereof is omitted.

According to this embodiment, the movable part covers the fixed part,
It is possible to enhance the waterproof and dustproof functions for the drive unit.

The present invention is not limited to the above embodiment,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, (1) in a non-contact flat type XY table, each tip has a plurality of teeth aligned in one direction and is installed at a predetermined interval. On the core member having a core member having at least four pole pieces that are excited by a propulsion guide coil wound on the pole piece and adjacent to the propulsion guide magnetic pole. It has first and second linear motor magnetic poles that are integrated with a magnetic attraction pole that is excited by a wound suction coil, and the directions of the tooth rows of the first and second linear motor magnetic poles are orthogonal to each other. A fixed body arranged as described above, a movable body having a plurality of tooth rows facing the tooth rows of the magnetic poles of the respective linear motors and having a constant pitch and aligned in the tooth row direction, and the fixed body. Displacement detecting means for detecting relative displacement between the movable body and the movable body And a control means for adjusting a gap between the fixed body and the movable body based on a detection value from the displacement detection means and for propelling the movable body in the X and Y directions in a magnetically levitated state. Therefore, the movable body can be moved in the XY directions in a non-contact state, and its control is extremely smooth. Moreover, the levitation force of the movable body having the table surface can be easily adjusted by changing the magnetic flux generated in the attraction magnetic pole by increasing / decreasing the current supplied to the attraction coil. In particular, it is necessary to frequently adjust the levitation force of the movable body according to the weight of the sample set on the table surface, which is effective.

(2) In addition to the effect of (1) above, a direct drive type actuator is configured, and the configuration is simple and compact.

(3) The movable body only needs to be provided with a tooth row, and it is not necessary to dispose an electromagnetic device for generating a magnetic force.

Therefore, it is not necessary to connect a wire for supplying electricity, the movement of the movable body is smooth, and the temperature of the table surface is not increased due to heating of the electromagnetic device.
It is possible to provide a table capable of appropriately managing the temperature of the table surface.

(4) Since it does not require mechanical bearings, it is suitable for use in harsh environments such as dust-free semiconductor factories, biotechnology-related factories, or high vacuum atmospheres. Further, as compared with mechanical bearings, lubrication is unnecessary and maintenance is easy.

[Brief description of drawings]

1 is a partially cutaway perspective view of a non-contact flat type XY table showing an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a sectional view taken along line III-III ′ of FIG. Fig. 4 shows IV- in Fig. 2.
IV 'sectional view, FIG. 5 is a perspective view of a linear motor magnetic pole, FIG. 6 is an operation explanatory view of the linear motor magnetic pole, FIG. 7 is a schematic configuration diagram of a non-contact plane type XY table, FIG. 8 and FIG. FIG. 9 is a microstep drive current waveform diagram, FIG. 9 is a microstep drive system configuration diagram, FIG. 11 is an excitation sequence diagram, and FIG. 12 is a non-contact plane type X showing another embodiment of the present invention.
FIG. 13 is a partial plan view of the Y table, and FIG. 13 is XIII-XII in FIG.
It is a sectional view taken along the line I ′. 1,43 …… Fixed body, 2,44 …… Linear motor magnetic pole, 3,
46 ... Gap detector, 4, 45 ... Movable body, 5 ... Tooth row, 21 ... Electronic control unit, 22 ... Power supply, 23 ... Drive circuit.

Claims (5)

[Claims] 1. (a) A core member having a plurality of teeth arranged in one direction at each tip and having at least four pole pieces arranged at predetermined intervals, and wound on the pole pieces. A magnetic pole for propulsion guidance excited by a coil for propulsion guidance, and a magnetic pole for attraction excited by a coil for attraction wound adjacent to the magnetic pole for propulsion guidance on the core member. A fixed body having a second linear motor magnetic pole and arranged so that the tooth rows of the first and second linear motor magnetic poles are orthogonal to each other; (b) the tooth row of the magnetic poles of each linear motor A movable body having a plurality of tooth rows that are opposed to each other and have a constant pitch and are aligned in the direction of the tooth row, and (c) a displacement detection unit that detects a relative displacement between the fixed body and the movable body, (d) A gap between the fixed body and the movable body based on the detection value from the displacement detection means. And a control means for adjusting the position of the movable body and propelling the movable body in the magnetically levitated state in the X and Y directions. 2. The non-contact plane type XY table according to claim 1, wherein two pairs of the linear motor magnetic poles are arranged in directions orthogonal to each other. 3. A means for supplying a sine-wave current and a cosine-wave current to the propulsion guide coil, and performing micro-step driving by the current flowing in each of these phases. The non-contact plane type XY table according to item 1. 4. A displacement of the movable body in a traveling direction is detected by the displacement detecting means during the microstep driving,
The non-contact plane type XY table according to claim 3, further comprising means for performing closed loop control so that a constant excitation lead angle is obtained based on the detected value. 5. An arrangement according to claim 1, wherein the magnetic motors are arranged such that the excitation phases of a plurality of linear motor magnetic poles arranged in the traveling direction of the movable body are shifted by π / 4. Contact flat type XY table.