JPH0775442B2 - Magnetic levitation carrier - Google Patents

Description

The present invention relates to a magnetic levitation transfer apparatus, and more particularly, to a magnetic levitation transfer apparatus suitable for transferring a silicon wafer or the like between semiconductor manufacturing apparatuses and inspection apparatuses in a clean room. It relates to the device.

[Prior art]

2. Description of the Related Art Conventionally, in a clean room used for semiconductor manufacturing, a transfer device for transferring a silicon wafer or the like is provided between a semiconductor manufacturing device and an inspection device. A contact-type transfer device in which wheels using rolling bearings as bearings roll on guide rails is used for this transfer device.

[Problems to be Solved by the Invention]

In the above-mentioned conventional contact type transfer device, a lubricant is often used for the rolling bearing and the like, and there is a problem that the clean room is contaminated by the splash of the lubricant or the vapor.

In addition, there is a problem that the structural member is worn at the contact portion and causes dust generation, and these contaminants adhere to the silicon wafer to reduce the product yield.

Further, in the contact type transfer device, rails having a large radius have to be laid in order to change the transfer direction, and there is also a problem that a wide space is required for the direction change.

The present invention has been made in view of the above points, and eliminates the above problems and solves the problem of dust generation caused by contamination with lubricants and sliding of parts. It is an object of the present invention to provide a magnetic levitation transfer device that does not contaminate the product, has a long life, can be maintenance-free, and requires a small installation space.

[Means for Solving the Problems]

In order to solve the above problems, the present invention includes a moving part (100) and a fixed part (200), and the moving part (100) has a fixed part (20).
0) is a magnetic levitation device that levitates and moves with a magnetic force, and the moving part (100) has a levitation floor plate (2) on which the transported object (1) is placed and a flat surface made of a magnetic material. A structure including a yoke flat plate (4), and a connecting rod (3) that connects the floating floor plate (2) and the yoke flat plate (4) at respective center positions with a predetermined gap, The fixed part (200) has a frame (5) fixed to the installation floor (50), and the connecting rod (3) is attached to the frame (5) by moving the moving part (100).
Has a notch (10) through which a plurality of stator electromagnets (6) are fixed on both sides of the notch (10) so that they can face the plane of the yoke plate (4). The yoke plate (4) has a rectangular shape, and the interval between each of the plurality of stator electromagnets (6) is approximately half the length of the side of the yoke plate (4) in the moving direction. The stator electromagnet (6) has a substantially circular cross-sectional shape, and the distance between the frame (5) and the plane of the yoke flat plate (4) is detected at the center of the stator electromagnet (6). The sensor (8) is fixed, and the plane of the yoke plate (4) facing the stator electromagnet (6) faces the stator electromagnet (6) along the moving direction of the yoke plate (4). Exciting electric field provided with a convex portion (9) having a width substantially equal to the diameter and receiving a detection signal from the sensor (8) and supplying it to the stator electromagnet (6). It is characterized by comprising an electromagnet control circuit for controlling the flow and a linear motor comprising a primary coil (30) fixed to the frame (5) with the yoke flat plate (4) as a secondary conductor.

Further, the cutouts (10) of the frame (5) and the plurality of stator electromagnets (6) arranged on both sides thereof are orthogonal to the cutouts (10) of the other frame (5) and arranged on both sides thereof. The plurality of stator electromagnets (6) are arranged.

The connecting rod (3) is characterized by being made of a material that converts vibration energy into heat energy.

[Action]

According to the present invention, by constructing the magnetic levitation transport device as described above, the yoke flat plate 4 is moved by supplying the exciting current to the stator electromagnets 6 provided in one row on each side of the notch 10 of the frame 5. A magnetic force for attracting is generated, the yoke plate 4 is levitated, and the floating floor plate 2 connected to the yoke plate 4 by a connecting rod 3 is also levitated.
By supplying the current to the next coil 30, the moving unit 100 can be moved in a predetermined direction in a non-contact manner. At this time, the connecting rod 3 passes through the notch 10.

The stator electromagnet 6 has a substantially circular cross-sectional shape, and the sensor 8 is arranged in the central portion, so that the sensor 8 serves as the yoke plate 4.
And the stator electromagnet 6 are detected, the detection signal is output to the electromagnet control circuit, and the exciting current supplied to the stator electromagnet 6 is controlled. Therefore, between the yoke flat plate 4 and the stator electromagnet 6. The gap d is always kept at a predetermined interval.

Further, by disposing the stator electromagnets 6 so that the intervals between the stator electromagnets 6 are approximately half the lengths of the sides of the yoke plate 4 in the moving direction, the yoke plate 4 is always attracted to the four stator electromagnets 6. As a result, it is possible to stably rise from the frame 5.

Further, by providing the convex portion 9 having a width substantially equal to the diameter of the stator electromagnet 6 along the moving direction of the yoke flat plate 4 on the surface of the yoke flat plate 4 facing the stator electromagnet 6, Even if the tip portion of 6 and the convex portion 9 are deviated from each other in the direction perpendicular to the moving direction, the restoring force is generated by the magnetic force in the oblique direction generated therebetween, and the yoke flat plate 4 is always located in the central portion of the convex portion 9. It is pulled back and always points in the direction of movement.

Further, since the frame 5 and the plurality of stator electromagnets 6 arranged on both sides thereof are orthogonal to the other frame 5 and the plurality of stator electromagnets 6 arranged on both sides thereof, the moving unit 100 is When this crossing point is reached, the moving direction of the moving unit 100 can be changed to the perpendicular direction by supplying the current supplied to the primary coil 30 forming the linear motor to the primary coil 30 in a direction different from this moving direction.

In addition, by forming the connecting rod 3 that connects the floating floor plate 2 and the yoke flat plate 4 with a material that converts vibration energy into heat energy, yawing that may occur in a magnetic levitation transfer device that is a "spring / weight vibration system". Since vibrations of pitching and pitching are dissipated as heat energy, these vibrations can be reduced.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing the structure of a magnetic levitation transfer device according to an embodiment of the present invention, FIG. 2 is a view showing the structures of an electromagnet and a displacement sensor fixed to a transfer device frame, and FIG. It is a sectional top view of the AA arrow direction of FIG.

As shown in FIG. 1, the magnetic levitation transport device has a moving part 10
It is composed of 0 and a fixed part 200.

The moving unit 100 has a structure in which the floating floor plate 2 on which the transported object 1 is loaded and the yoke flat plate 4 having a horizontal surface made of a magnetic material are connected at predetermined center positions by connecting rods 3.

The fixing portion 200 has a structure in which the frame 5 is fixed to the installation floor 50 and a linear motor stator (primary coil) 30 is provided in the center of the frame 5.

A groove-shaped notch 10 is formed in the frame 5 so that the connecting rod 3 can move therethrough. A plurality of stator electromagnets 6 are fixed to the frame 5 on both sides of the notch 10 in a row and so as to face the yoke flat plate 4. The stator electromagnet 6 has a circular cross-sectional shape and generates a magnetomotive force that gives an upward attraction force to the yoke flat plate 4.

2 (a) is a longitudinal sectional view of the stator electromagnet 6, FIG. 2 (b).
Is a view of the stator electromagnet 6 as seen from below. As shown in the figure, the stator electromagnet 6 has a core 6a having a circular cross section, and an annular groove is formed on the tip end face (lower end face) of the core 6a. 6b is formed, and an annular coil 7 is fitted in the groove 6b. A sensor 8 is fixed to the central portion of the stator electromagnet 6, and a coil 7 is arranged on the outer peripheral portion of the sensor 8. The cross-sectional shape of the stator electromagnet 6 does not have to be a perfect circle, but may be a substantially circular shape so that the annular coil 7 can be wound.

The sensor 8 detects the relative displacement between the stator electromagnet 6 and the yoke flat plate 4, and this output signal is guided to the electromagnet control circuit, and this electromagnet control circuit causes a small gap between the stator electromagnet 6 and the yoke flat plate 4. The exciting current supplied to the stator electromagnet 6 is controlled so that d becomes constant.

Further, since the convex portion 9 having a width substantially equal to the diameter of the stator electromagnet 6 is provided in the moving direction on the surface of the floating yoke plate 4 facing the stator electromagnet 6, the tip of the stator electromagnet 6 is provided. When a deviation in the direction perpendicular to the moving direction occurs between the convex portion 9 and the convex portion 9, a restoring force is exerted by the magnetic flux in the oblique direction generated therebetween and the floating floor plate 2 does not always deviate from a fixed trajectory.

Further, as shown in FIG. 3, the stator electromagnets 6 or the interval l ₂ between the convex portions 9 on the surface of the yoke plate 4 are fixed so as to be approximately half the width l of the yoke plate 4 in the moving direction. When the child electromagnet 6 is arranged, the floating floor plate 2 and the yoke flat plate 4 are always attracted by the four stator electromagnets 6 no matter which position the frame 5 is moved.
Therefore, it is possible to obtain a stable levitating state.

It should be noted that the stable levitation is more stable as the gap between the stator electromagnets 6 is smaller, but by making the width approximately 1 of the width l of the yoke flat plate 4 in the moving direction as in the present embodiment, the minimum stator is obtained. A stable levitation force can be obtained by the electromagnet 6.

Further, in FIG. 3, l'when the moving direction is the lateral direction.
And l ₂ ′ are the same.

In addition, the magnetic levitation transport device uses a magnetic force between the stator electromagnet 6 and the yoke plate 4 as a spring, a moving part 100 including the yoke plate 4, the connecting rod 3, the floating floor plate 2, and an accessory fixed to these. Since a "spring / weight vibration system" having a weight is configured, yawing and pitching vibrations may occur and continue on the floating floor plate 2. Here, if the connecting rod 3 is made of a material capable of converting vibration energy into heat energy, such as a vibration-proof rubber, the generated vibration can be reduced. The connecting rod 3 may be made of any material that can convert vibration energy into heat energy such as wood and plastic, as well as vibration-proof rubber.

FIG. 4 is a plan view showing the relative positions of the notch 10 of the frame 5, the stator electromagnet 6 and the linear motor stator (primary coil) 30. The primary coil 30 is fixed to the frame 5. Here, the yoke plate 4 is used as the secondary conductor, and the primary coil is used.
A linear motor with 30 as a stator is constructed. This linear motor is generally an induction linear motor, but a permanent magnet may be used instead of the yoke flat plate 4 to provide a synchronous linear motor. This makes it possible to accurately control the position of the moving unit 100. The floating floor plate 2 can be driven without contact by the linear motor.

In addition, as shown in FIG.
And a plurality of stator electromagnets 6 and a primary coil of a linear motor
Two systems are provided so that 30 are orthogonal to the X direction and the Y direction, and the primary coil 30 that conducts electricity at the intersection of the notches 10 is, for example, X
By changing the direction to the Y direction, the floating floor plate 2 can be turned at right angles and moved.

In this embodiment, the cross section of the stator electromagnet 6 has a circular shape, and its operation will be described with reference to FIGS. 6 and 7. 6 and 7, (a) is a plan view,
(B) is a side view. 6 and 7 show a case where a rectangular electromagnet 501 is used instead of the stator electromagnet 6 having a circular cross section. Note that 501a represents an exciting coil of the electromagnet 501. When the square electromagnet 501 is used as the stator electromagnet, the convex portion 9 of the yoke plate 4 and the square electromagnet 501 shown in FIG. 6 are used.
In the arrangement relationship, the passive restoring force sufficiently works in the guide direction A with respect to the moving direction S, but the restoring force generated in the arrangement relationship shown in FIG. 7 is small. Generally, this restoring force is approximately proportional to the outer width dimension 1 _M or the pole thickness dimension 2 × 1 _m of the rectangular electromagnet 501. Therefore, the same restoring force can be obtained by using a rectangular electromagnet whose dimension 1 _M is equal to dimension 2 × 1 _m , but TM and TM ′ indicating the width of the convex portion 9 are different,
Directionality occurs. This is very inconvenient because stable movement is impaired when the carrier table constituted by the yoke plate 4 is rotated by 90 ° for some reason. Further, if the rectangular electromagnet 501 is created so that TM and TM ′ indicating the width of the convex portion 9 are equal to each other, the gap C _m between the magnetic poles becomes 0, so that the magnet does not function as a magnet, which is meaningless. Will be things.

Therefore, by using the fixed electromagnet 6 having a circular cross section shown in FIG. 2, a sufficient passive restoring force can be obtained regardless of the guide direction with respect to the moving direction.

FIG. 5 is a block diagram showing an example of a control circuit for controlling the exciting current of the magnetically levitated stator electromagnet 6. As shown in the figure, the electromagnet control circuit includes a phase compensation circuit 22, a power amplifier.
Composed of 23. The small gap d between the stator electromagnet 6 and the yoke flat plate 4 is detected by the non-contact sensor 8, the detection output signal is amplified by the relative displacement sensor amplifier 21, and the output is supplied to the phase compensation circuit 22 and the power amplifier 23. Then, the exciting current is supplied to the coil 7 of the stator electromagnet 6. The current of the coil 7 is detected by the feedback resistor 24, and the power amplifier 23
Is fed back to control the current flowing through the coil 7.

〔The invention's effect〕

As described above, according to the present invention, the following excellent effects can be obtained.

(1) Since the transfer device is a non-contact magnetic levitation transfer device that does not require a lubricant, no lubricant is splashed or dust is not generated from the contact portion, so that a clean space can be realized.

(2) Further, since it is non-contact, there is no problem of wear of parts, and it becomes a highly durable and long-life transport device, and maintenance-free can be realized.

(3) By arranging the stator electromagnets (6) so that each interval is approximately half the length of the side of the yoke plate (4) in the moving direction, the yoke plate (4) is always four pieces. The magnetic attraction force of the stator electromagnet (6) can be suppressed to the minimum necessary for stable levitation while being attracted to the stator electromagnet (6) and maintaining a stable levitation state.

(4) Further, a convex having a width substantially equal to the diameter of the stator electromagnet (6) along the moving direction of the yoke flat plate (4) on the surface of the yoke flat plate (4) facing the stator electromagnet (6). By providing the portion (9), even if a displacement in the direction perpendicular to the moving direction occurs between the tip of the stator electromagnet (6) and the convex portion (9), the restoration due to the magnetic force in the oblique direction generated therebetween. Since a force is generated and the yoke plate (4) is always pulled back to the center of the convex portion (9), the moving portion (100) can always move on a stable trajectory.

(5) Further, perpendicular to the notch (10) of the frame (5) and a plurality of stator electromagnets (6) arranged on both sides of the notch (10),
By arranging the notch (10) of the other frame (5) and a plurality of stator electromagnets (6) arranged on both sides of the notch (10), when the moving part (100) reaches this intersection, a linear motor is constructed. By supplying the current supplied to the primary coil (30) to the primary coil (30) in a direction different from this moving direction, the moving direction of the moving part (100) can be changed to a right angle direction, so a large space is required. You can change the direction of the right angle without

(6) Further, the connecting rod (3) connecting the floating plate floor (2) and the yoke flat plate (4) is made of a material that converts vibration energy into heat energy, so that the connecting rod (3) is vibration-proof. The action can be expected and stable conveyance can be performed without unnecessary vibration.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a magnetic levitation transfer apparatus according to an embodiment of the present invention, FIG. 2 is a view showing a stator electromagnet, FIG. 1 (a) is an enlarged vertical cross-sectional view, and FIG. Is a bottom view seen from below, FIG. 3 is a sectional plan view taken along the line AA of FIG. 1, and FIG.
FIG. 5 is a plan view showing the relative positions of the notch 10 of the frame 5, the stator electromagnet 6 and the primary coil 30 of the linear motor, and FIG. 5 is a block diagram showing the configuration example of the electromagnet control circuit, FIG. 6 and FIG. FIG. 6 is a diagram for explaining the action of a stator electromagnet. In the figure, 1 ... Transported object, 2 ... Floating floor plate, 3 ... Connecting rod, 4 ... Yoke flat plate, 5 ... Frame, 6 ... Stator electromagnet, 7 ... Coil, 8 ... Sensor , 9 ... convex, 10 ...
… Frame cutouts, 21… Relative displacement sensor amplifier,
22 ... Phase compensation circuit, 23 ... Power amplifier, 24 ... Feedback resistance, 30 ... Linear motor primary coil, 50 ...
… Installation floor, 100 …… moving part, 200 …… fixed part.

Claims (3)

[Claims] 1. A moving part (100) and a fixed part (200) are provided,
The moving unit (100) is a magnetic levitation device that levitates and moves with respect to the fixed unit (200) by a magnetic force, and the moving unit (100) is a floating floor plate (on which a transported object (1) is placed. 2) and a yoke plate having a flat surface made of magnetic material (4)
And a connecting rod (3) that connects the floating floor plate (2) and the yoke flat plate (4) at respective center positions with a predetermined gap.
The stationary part (200) has a frame (5) fixed to the installation floor (50), and the moving part (10) is provided in the frame (5).
0) has a notch (10) through which the connecting rod (3) passes, and a plurality of stator electromagnets (6) are arranged on each side of the notch (10) in a row. It is a structure fixed so as to face the plane of the flat plate (4), the yoke plate (4) has a rectangular shape, and the intervals between the stator electromagnets (6) are the yoke plate (4). 4) is approximately half the length of the side in the moving direction, and the stator electromagnet (6) has a substantially circular cross-sectional shape,
A sensor (8) for detecting a distance between the frame (5) and the plane of the yoke plate (4) is provided at the center of the stator electromagnet (6).
Is fixed to the plane of the yoke plate (4) facing the stator electromagnet (6) along the moving direction of the yoke plate (4) and the diameter of the stator electromagnet (6). Convex portion (9) having a substantially equal width
An electromagnet control circuit for controlling an exciting current supplied to the stator electromagnet (6) by receiving a detection signal from the sensor (8), and the yoke flat plate (4) as a secondary conductor and the frame (5 )
A magnetic levitation transport device, comprising: a linear motor having a primary coil (30) fixed to the. 2. A cutout (10) of another frame (5) perpendicular to the cutout (10) of the frame (5) and the plurality of stator electromagnets (6) arranged on both sides thereof. The magnetic levitation transfer device according to claim 1, wherein the plurality of stator electromagnets (6) arranged on both sides thereof are arranged. 3. The magnetic levitation transfer apparatus according to claim 1, wherein the connecting rod (3) is made of a material that converts vibration energy into heat energy.