JP2006203979A - Flat motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat motor capable of avoiding collision at the time of returning to its origin. <P>SOLUTION: In the flat motor, two sliders and a platen have their origin return positions respectively. The motor is equipped with overhanging sections which are mounted on each side of the origin return positions of the two sliders and movably overhang from the outer edge of the platen, and a means for blocking which is mounted at the center of the platen and is large enough not to move to other areas as far as the overhang sections overhang from the platen when the sliders move. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a planar motor that can avoid a collision at the time of return to origin.

  Prior art documents related to planar motors include the following.

JP 2000-65970 A

7 is a diagram illustrating the configuration of a conventional example that is generally used conventionally, FIG. 8 is a configuration diagram of the main part of FIG. 7, FIG. 9 is a configuration diagram of the main part of FIG. 7, and FIG. FIG. 11 is a configuration diagram of a main part of FIG.
In FIG. 7, the lattice platen 30 has teeth formed at a constant pitch along the X-axis direction and the Y-axis direction. In the figure, only a part of the teeth is shown for simplification.
Such a lattice platen 30 is formed by cutting grooves in a lattice shape on a flat surface. The lattice platen 30 is made of a magnetic material.

An object to be positioned is placed on the slider portion 31.
The levitation means 32 levitates the slider portion 31 on the lattice platen 30.
A nozzle is provided on the surface of the slider portion 31 that faces the grid platen 30, and the levitation force is obtained by the levitation means 32 ejecting compressed air from the nozzle.
Air blown from the nozzle flows between the slider portion 31 and the lattice platen 30 to constitute an air bearing. The gap between the slider portion 31 and the grating platen 30 is about several tens of μm.

The Y-axis motor 33 is mounted on the slider portion 31, and teeth 332 are formed at a constant pitch in the Y-axis direction on the surface of the core 331 that faces the lattice platen 30.
The Y-axis motor 33 generates a magnetic attractive force between the teeth 332 and the teeth 301 of the lattice platen 30 to move the slider portion in the Y-axis direction.
The coil 333 is wound around the core 331.

The X-axis motors 34 and 35 are mounted at positions symmetrical with respect to the center of the slider portion 31.
In the X-axis motors 34 and 35, teeth 342 and 352 are formed at a constant pitch in the X-axis direction on the surfaces of the cores 341 and 351 facing the lattice platen 30.
The X-axis motors 34 and 35 generate a magnetic attractive force between the teeth 342 and 352 and the teeth 301 to move the slider portion in the X-axis direction.
The coils 343 and 353 are wound around the cores 341 and 351.

The connecting members 311 and 312 connect the Y-axis motor 33 and the X-axis motors 34 and 35.
The X-axis mirror 36 is mounted on the side surface of the grating platen 30 and has a mirror surface in the Y-axis direction.
The Y-axis mirror 37 is mounted on the side surface of the grating platen 30 and has a mirror surface in the X-axis direction.

The Y-axis sensor 38 is mounted on the Y-axis motor 33 and detects the position of the slider portion 31 in the Y-axis direction.
The Y-axis sensor 38 is an interferometer that irradiates the Y-axis mirror 37 with light, receives the reflected light, and detects the position of the slider portion 31 in the Y-axis direction using light interference.

X-axis sensors 39 and 40 are mounted on the X-axis motors 34 and 35, respectively, and detect the position of the slider portion 31 in the X-axis direction.
The X-axis sensors 39 and 40 are interferometers that irradiate the X-axis mirror 36 with light, receive the reflected light, and detect the position of the slider portion 31 in the Y-axis direction using light interference.

The Y-axis control unit 41 feedback-controls the position of the slider unit 31 based on the detection position of the Y-axis sensor 38.
The X-axis control units 42 and 43 perform feedback control of the position of the slider unit 31 based on the detection positions of the X-axis sensors 39 and 40, respectively.

The correction means 44 and 45 are provided for the X-axis control units 42 and 43, respectively, and hold correction tables 46 and 47 in which the position of the slider unit and the correction amount for removing yawing of the slider unit are associated.
The correction means 44 and 45 read the correction amount from the correction tables 46 and 47 based on the given command position, and correct the command position given to the X-axis control units 42 and 43 with the read correction amount.

The data in the correction tables 46 and 47 are data obtained by calibration. The correcting means 44 and 45 are provided for correcting a bending due to a mechanical error between the X-axis mirror 36 and the Y-axis mirror 37.
If the bends of the X-axis mirror 36 and the Y-axis mirror 37 do not affect the position detection, the correcting means 44 and 45 need not be provided.

FIG. 8 is a configuration diagram of a surface of the slider portion 31 that faces the lattice platen 30.
FIG. 9 is a cross-sectional view taken along the line AA ′ of FIG.
In these drawings, an example of the X-axis motor 34 is shown. Other motors have the same configuration.
The groove 344 is formed on the opposing surface.
The nozzle 345 is formed in the groove 344 and ejects compressed air supplied from the levitation means 32.

The embedded member 346 is embedded in the recess of the tooth 342. The embedded member 346 is made of a nonmagnetic material.
By applying the coating on the facing surface, the embedded member 346 can be formed in the recess of the tooth 342.

The compressed air ejected from the nozzle 345 flows along the groove 344, and the core 341 is levitated by the pressure of the compressed air.
The embedded member 346 prevents the compressed air from leaking outside through the recess of the tooth 342.

FIG. 10 is a diagram illustrating a configuration example of the control unit in FIG.
Although FIG. 10 shows an example of the X-axis control unit 42, the X-axis control unit 43 and the Y-axis control unit 41 have the same configuration.
In FIG. 10, a photodiode array (PDA) 420 detects the brightness of the interference fringes formed on the X-axis sensor 39.

The signal processing circuit 421 performs arithmetic processing on the detection signal of the PDA 420.
Comparators 422 and 423 generate an A-phase pulse and a B-phase pulse from the calculation signal of the signal processing circuit 421.

The direction discriminating circuit 424 discriminates the moving direction of the slider unit 31 from the phase relationship between the A-phase pulse and the B-phase pulse, and generates an up pulse or a down pulse according to the discrimination result.
The up / down counter 425 counts up or down according to the up pulse or the down pulse.
The count of the up / down counter 425 becomes the detection position of the slider unit 31.

In the initial state, it is known in advance how much the phases of the rotor teeth and the stator teeth are shifted when a known current is passed through each phase coil of the X-axis motor 34.
The value of the up / down counter 425 at this time is set to a reference value, for example, 0.
As the slider 31 moves, the up / down counter 425 detects the position by counting up or down from the reference value.
In this way, position detection is performed incrementally.

The subtractor 426 obtains a deviation between the position command value X0 and the count X1 (detection position) of the up / down counter 425.
The position control means 427 outputs a control signal for performing position feedback control of the X-axis motor 34 based on the deviation obtained by the subtractor 426.
The speed calculation means 428 detects the moving speed of the slider portion 31 from the changing speed of the count X1 of the up / down counter 425.
The speed calculation means 428 is, for example, an F / V converter.

A subtractor 429 obtains a deviation between the control signal of the position control means 427 and the speed calculation means 428.
The speed control means 430 outputs a control signal for speed feedback control of the X-axis motor 34 based on the deviation obtained by the subtractor 429.

In the sin table 431, the count of the up / down counter 425 and the sin value are stored correspondingly.
When the X-axis motor 34 is a three-phase motor, when the count of the up / down counter 425 is given, the values of sin (θ + 120 °) and sin (θ−120 °) are read from the sin table 431.
θ is an angle that changes according to the count of the up / down counter 425.

Multiplexing digital-analog converters (MDAs) 432 and 4334 are analog input signals obtained from the speed control unit 430, sin (θ + 120 °) read from the sin table 431, and sin (θ-120). A current command value (I is a current amplitude) of Isin (θ + 120 °) and Isin (θ−120 °) is output using the value of °) as a gain setting signal.
Here, the reason why the phases of the two command values are shifted by 120 ° is that the motor is a three-phase motor. When the number of phases is different, the phase shift has another value.

The current sensors 434 and 435 detect the coil current flowing in the coils L1 and L2 of the X-axis motor 34.
Subtractors 436 and 437 determine the deviations of Isin (θ + 120 °) and Isin (θ−120 °) and current sensors 434 and 435, respectively.
Pulse width modulation circuits (referred to as PWM circuits) 438 and 439 generate pulse width modulation signals (referred to as PWM signals) for feedback control of the excitation current of the motor coil based on the deviation obtained by the current sensors 434 and 435. And output.

A subtracter 440 subtracts the PWM signals from the PWM circuits 438 and 439.
The PWM circuit 441 generates a PWM signal from the subtraction signal of the subtracter 440.
The drive circuit 442 is a bridge-type inverter circuit, and drives the X-axis motor 34 based on the three-phase PWM signals of the PWM circuits 438, 439, and 441.

In the circuit of FIG. 10, when the power is turned on, a known current is passed through each coil of the X-axis motor 34, and the rotor teeth of the motor and the teeth of the stator are set to a known phase relationship.
The phase relationship set in this way is set as the origin of the commutation angle.
At this time, the count of the up / down counter 425 is set to a reference value, for example, 0.

  Thereafter, the detected value of the X-axis sensor 39 changes with the movement of the slider unit 31, and the current command values Isin (θ + 120 °) and Isin (θ−120 °) change according to the change of the count of the up / down counter 425. The current is controlled by changing the value of θ.

FIG. 11 is a diagram showing a configuration example of the sensor of FIG.
The Y-axis sensor 38 and the X-axis sensors 39 and 40 in FIG. 7 have the same configuration.
The X-axis sensor 39 will be described as an example.
In FIG. 11, the laser light source 391 emits laser light.
Mirrors 392 and 393, a half mirror 394, a deflection beam splitter (referred to as PBS) 395, a λ / 4 plate 396, and a corner cube 397 are disposed in the optical path of the emitted light from the laser light source 391.

The light emitted from the laser light source 391 includes light that travels in the path of the half mirror 394, the mirror 393, the mirror 392, and the half mirror 394 and travels in the direction a in the figure.
This light is the first light.
The light emitted from the laser light source 391 includes half mirror 394, PBS 395, λ / 4 plate 396, X axis mirror 36, λ / 4 plate 396, PBS 395, corner cube 397, λ / 4 plate 396, and X axis mirror. 36, λ / 4 plate 396, PBS 395, and half mirror 394. The light travels in the direction a in the figure.
This light is the second light.

The first light and the second light described above interfere to form an interference fringe S. The PDA 398 detects the interference fringes S. The PDA 398 includes four photodiodes 398A to 398D.
The four photodiodes 398A to 398D are arranged within one pitch of the interference fringes S.
The photodiodes 398A to 398D are arranged so as to be shifted by P / 4 (P is a pitch of interference fringes).

The subtractor 399 performs an operation of (detection signal of the photodiode 398A) − (detection signal of the photodiode 398C).
The subtractor 400 is (detection signal of the photodiode 398B) − (photodiode 39).
8D detection signal).
The subtracters 399 and 400 constitute the signal processing circuit 421 in FIG.

When the slider portion 31 moves, the interference fringes move in the direction dd ′ in FIG.
When the interference fringes move, the light and dark portions of the interference fringes that hit the photodiodes 398A to 398D move, and the detection values of the photodiodes 398A to 398D change. Based on this, the position of the slider portion 31 is detected.

When the interference fringes move in the d direction, the photodiode outputs VA to VD are as follows.
VA = K [1 + msin {x · 2π / (λ / 4)}] + Kn
VB = K [1 + mcos {x · 2π / (λ / 4)}] + Kn
VC = K [1-msin {x · 2π / (λ / 4)}] + Kn
VD = K [1-mcos {x · 2π / (λ / 4)}] + Kn
x: distance to be detected, K, m: coefficient, Kn: noise component

The subtraction signals of the subtracters 399 and 400 are as follows.
VA−VC = 2 mKsin {x · 2π / (λ / 4)}
VB−VD = 2 mK cos {x · 2π / (λ / 4)}
As a result of the subtraction, the DC noise component Kn generated by the disturbance light is canceled.
Signals VA-VC and VB-VD are converted into the aforementioned A-phase pulse and B-phase pulse.
When the interference fringe moves in the direction d ', the phase relationship between the signals VA-VC and VB-VD is reversed.

With the above configuration, the operation of the XY stage in FIG. 7 will be described.
When the power is turned on, a known current is supplied to each coil of the X-axis motor 34 to position the slider portion 31 at the reference position (this is referred to as an origin return operation).
When the slider unit 31 moves in the X-axis direction and the Y-axis direction from the reference position, the two-dimensional position is detected incrementally by the X-axis sensor 39.40 and the Y-axis sensor 38.

When the bending of the X-axis mirror 36 and the Y-axis mirror 37 does not affect the position detection, the correcting means 44 and 45 are not provided. At this time, the same command position is given to the X-axis controllers 42 and 43.
For this reason, the X-axis motors 34 and 35 position the slider unit 31 at the same X-axis position by feedback control of the X-axis control units 42 and 43.
Thereby, yawing of the slider part 31 is removed.

A case where the bending of the X-axis mirror 36 and the Y-axis mirror 37 affects the position detection will be described.
At this time, correction means 44 and 45 are provided.
Before performing the positioning operation, the XY stage is calibrated.

When the slider unit 31 is positioned at the coordinates (X1, Y1) in the calibration, yawing occurs in the slider unit 31 due to a mechanical error of the XY stage and the detected values of the X-axis sensors 39 and 40 are X1 + ΔX1. And X2−ΔX2. At this time, (X1, Y1) and -ΔX1 are stored in correspondence in the correction table 46, and (X1, Y1) and + ΔX2 are stored in correspondence in the correction table 47.
The slider portion 31 is positioned at other positions to determine the correction amount. In this way, a correction table is created.

In the actual positioning operation, when the slider unit 31 is positioned at the coordinates (X1, Y1), the correction unit 44 corrects the command position given to the X-axis control unit 42 by −ΔX, and the correction unit 45 is the X-axis control unit. The command position given to 43 is corrected by + ΔX.
Thereby, yawing of the slider part 31 is removed.
In this way, the rotational deviation in the θ-axis direction of the slider portion 31 due to the bending of the mirror surface is corrected.

  A rotation control unit is provided for controlling the rotational position of the slider unit by adding a predetermined value to one command position and subtracting the predetermined value from the other command position with respect to the command position given to the X-axis control unit. A configuration may be used.

Further, the two X-axis sensors may detect the rotation angle of the slider portion based on the difference between the detection positions.
Further, a configuration may be adopted in which a mirror is mounted on the slider portion, and the positions of the X-axis sensor and the Y-axis sensor are fixed.

In the case of such a planar motor device having a single movable part (slider) configuration, the planar motor is incorporated in one work process.
As shown in FIG. 12, when a plurality of work processes exist in the apparatus, it is necessary to transfer the work target work to a planar motor in another process.
In FIG. 12, A1 and B1 are planar motor devices having a single movable part (slider) configuration, C1 is a workpiece transfer means, and LD is a semiconductor laser emission source (laser diode).
In this case, with respect to the conventional example of FIG. 7, the laser light source relationship is arranged not on the slider but on the platen side.
For the sake of clarity, details of the interferometer portion are omitted, and only the state of light distribution to each axis is described.

By the way, in the apparatus of FIG.
In a manufacturing apparatus that requires precise positioning, it is necessary to correct a shift of the workpiece mounting position caused by the transfer or adopt a moving method that does not cause a position error.
The time required to transfer the workpiece becomes wasted time and the production efficiency of the device is reduced.
Since it is necessary to arrange a workpiece transfer means necessary for workpiece transfer, the apparatus becomes large.

  In order to improve this, it is conceivable that a plurality of sliders are provided on a single platen, and a planar motor goes back and forth between processes while a workpiece is mounted.

Thus, when a plurality of sliders are provided on a single platen, the following problems occur.
Since the position detection value of the laser interferometer is not synchronized with the tooth pitch of the motor, it is necessary to operate the motor as a stepping motor and to synchronize the motor tooth position and the interferometer detection value. In addition, since the laser interferometer does not detect the absolute position, an origin return operation is required at the start of operation.
If multiple sliders are placed on the platen at this time, the positions of the sliders and the interferometer light will not be correct when the tooth alignment operation or home return operation is performed. An abnormal condition occurs, such as blocking the shaft, and manual recovery work is required, making it impossible to construct a stand-alone device.

For example, as shown in FIG. 13, if the A slider D1 moves to the position of the A origin sensor E1 and tries to move in the order of a → b, it collides with the B slider F1 during the movement of a.
Here, D1 is an A slider, F1 is a B slider, E1 is an A origin sensor, and G1 is a B origin sensor.
For example, as shown in FIG. 14, if the A slider D2 moves to the position of the A origin sensor E1 and tries to move in the order of b → a, it collides with the B slider F1 during the b movement.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and an object thereof is to provide a planar motor that can avoid a collision at the time of return to origin.

In order to achieve such a problem, in the present invention, in the planar motor of claim 1,
An overhang portion provided on the respective origin return position side of the two sliders and overhanging and movable from a peripheral portion of the platen, and the overhang portion provided in the center of the platen when the slider moves. Is provided with obstacle means having a size that cannot be moved to another region unless it is projected from the platen.

In the planar motor according to claim 2 of the present invention, in the planar motor according to claim 1,
The overhang portion is a plate-like protruding plate protruding from the slider.

In Claim 3 of this invention, in the planar motor of Claim 1,
It is characterized by that.

In a fourth aspect of the present invention, in the planar motor according to any one of the first to third aspects,
The overhang portion is composed of two poles protruding from the slider.

In claim 5 of the present invention, in the planar motor according to claim 4,
The pole is constituted by a pole having a circular cross section.

In claim 6 of the present invention, in the planar motor according to claim 4,
The pole may be a pole having a quadrangular cross section.

The present invention has the following effects.
Since the two slider positions can be mechanically limited, a flat motor can be obtained that can avoid a collision at the time of return to origin even if a malfunction of the slider is assumed.
Since a collision at the time of return to origin can be avoided without adding a sensor, a flat motor that is easy to control and inexpensive can be obtained.
A planar motor device having two sliders can be realized, and a planar motor that can contribute to improving the efficiency of the device can be obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view of a main part configuration of one embodiment of the present invention, FIG. 2 is a side view of the main part of FIG. 1, FIG. 3 is a main part part diagram of FIG. FIG. 5 is a side view of the main part of FIG. 4.

In FIG. 1, the overhang portions 51 and 52 are provided on the A and B origin sensor positions 55 and 56 side of the two A and B sliders 53 and 54, respectively, and can be moved by projecting from the peripheral portion of the platen 57. It is configured.
That is, the overhang portions 51 and 52 are provided on opposite sides of the two A and B sliders 53 and 54, respectively.

In this case, as shown in FIGS. 2 and 3, the overhang portions 51 and 52 are constituted by plate-like projecting plates projecting from the A and B sliders 53 and 54.
That is, the heights of the overhang portions 51 and 52 are set so that there are no obstacles when passing over the end of the platen 57.

The obstruction means 61 is provided in the center of the platen 57, and has a size that cannot move to other regions unless the overhang portions 51 and 52 protrude from the platen 57 when the A and B sliders 53 and 54 move. .
In this case, as shown in FIGS. 1 and 2, the obstacle means 61 is formed of a circular pole that stands upright on the surface of the platen 57.

That is, the height of the pole 61 is set so as to collide with the overhang portions 51 and 52.
The size of the pole 61 is the distance L1 from the end of the platen 57 (vertical end in the figure) to the pole 61, which is the sum of the length L2 of the overhang portions 51 and 52 and the length L3 of the A and B sliders 53 and 54. It is set to be shorter than the specified length.

In the above configuration, the positions where the respective A and B sliders 53 and 54 can be taken are limited, and as shown in FIG. 4, when moving to the left and right areas at the portion divided by the pole 61, the A slider 53 is on the lower side. B sliders 53 and 54 are on the upper side.
In the arrangement of FIG. 1, after the A and B sliders 53 and 54 are moved in the direction a (in the figure, the A slider 53 is down and the B slider 54 is up), in the b direction (in the figure, the A slider 53 is left and the B slider 54 is By moving to the right), the tooth alignment operation and the origin return operation can be performed without collision between the A and B sliders 53 and 54.

As a result,
Since the positions of the A and B sliders 53 and 54 can be mechanically limited, a flat motor capable of avoiding a collision at the time of return to origin can be obtained even if a malfunction of the A and B sliders 53 and 54 is assumed.
Since a collision at the time of return to origin can be avoided without adding a sensor, a flat motor that is easy to control and inexpensive can be obtained.
A planar motor device having two A and B sliders 53 and 54 can be realized, and a planar motor that can contribute to improving the efficiency of the device is obtained.

FIG. 6 is an explanatory view showing the configuration of the main part of another embodiment of the present invention.
In this embodiment, the overhang portions 71 and 72 are composed of two poles 711 and 721 protruding from the A and B sliders 53 and 54.

  In the above-described embodiment, the pole 61 has been described as circular. However, the present invention is not limited to this, and for example, a square may be used. In short, the obstruction means 61 of the sliders 53 and 54 may be used.

The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is principal part structure explanatory drawing of one Example of this invention. It is a principal part side view of FIG. It is a principal part figure of FIG. It is operation | movement explanatory drawing of FIG. It is a principal part side view of FIG. It is principal part structure explanatory drawing of the other Example of this invention. It is structure explanatory drawing of the prior art example generally used conventionally. It is a principal part block diagram of FIG. It is a principal part block diagram of FIG. It is a principal part block diagram of FIG. It is a principal part block diagram of FIG. It is composition explanatory drawing of the other conventional example generally used conventionally. It is operation | movement explanatory drawing of another prior art example generally used conventionally. It is operation | movement explanatory drawing of FIG.

Explanation of symbols

30 Grid platen 31 Slider unit 32 Levitating means 33 Y-axis motor 34 X-axis motor 35 X-axis motor 36 X-axis mirror 37 Y-axis mirror 38 Y-axis sensor 39 X-axis sensor 40 X-axis sensor 41 Y-axis control unit 42 X-axis control Part 43 X-axis control part 44 Correction means 45 Correction means 51 Overhang part 52 Overhang part 53 A slider 54 B slider 55 A Origin sensor position 56 B Origin sensor position 57 Platen 61 Obstacle means 61 Pole 71 Overhang part 711 Pole 72 Overhang 721 Pole LD Semiconductor laser light source

Claims (6)

In a planar motor with two sliders and a platen with a return to origin position,
An overhang portion that is provided on the respective origin return position side of the two sliders and that is movable overhanging from a peripheral portion of the platen;
A flat motor comprising: obstacle means provided at a center of the platen and having a size that cannot move to another region unless the overhang portion protrudes from the platen when the slider moves. The flat motor according to claim 1, wherein the overhang portion is a plate-like protruding plate protruding from the slider. The planar motor according to claim 1, wherein the overhang portion includes two poles protruding from the slider. The planar motor according to any one of claims 1 to 3, wherein the obstacle means is configured by a pole standing upright on the platen surface. The planar motor according to claim 4, wherein the pole is a pole having a circular cross section. The planar motor according to claim 4, wherein the pole is a pole having a square cross section.

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