JPH07137842A - Magnetic levitating conveyer - Google Patents

Abstract

PURPOSE:To convey an article in a clean condition on a track having a step difference by adjusting a magnetic field of electromagnets for giving levitating force to a conveying base, and conveying it while lifted on the track. CONSTITUTION:A device comrises a conveying base 16 having a secondary conductor consisting of at least partially non-magnetic further good conductor, many electromagnets 12 juxtaposed in a track surface and a control unit 15 for generating an alternating magnetic field in the electromagnet 12 and also generating an alternating magnetic field repulsive to an eddy current induced in the secondary conductor of the conveying base by this electromagnet to levitate the conveying base 16 on a track. The track is constituted of a plurality of track units 11A, 11B, 11C, 11D successively connected with a step difference each other, to detect a position of the conveying base 16 by a position detector 17, and also, while detecting a levitation amount of the conveying base 16 by a levitation amount detector 1, a quantity of AC current fed to the electromagnet 12 is arbitrarily adjusted by the control unit 15, so as to convey the conveying base 16 while lifted along the track having a step difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction-repulsion type magnetic levitation transporting device for levitating and transporting a carrier on a track by a repulsive magnetic force, and more particularly to raising and lowering the carrier on a track provided with a step. It is related to the device.

[0002]

2. Description of the Related Art For example, a wafer transfer apparatus in a semiconductor manufacturing process is required to prevent the transferred wafer from being contaminated by dust and scattered oil. For this reason, it is convenient to use a transfer device that avoids mechanical structures that easily cause dust and oil to scatter, and the magnetic force that causes the transfer table on which the wafer is placed to levitate on the track by the magnetic force of induced repulsion is used. The use of a levitation type carrier is being considered. In this magnetic levitation type transfer device, a secondary conductor (metal plate) made of a non-magnetic and good conductor is provided on a transfer table, and an alternating magnetic field is generated by passing an alternating current through an electromagnet provided on a track, thereby generating an alternating magnetic field. An alternating magnetic field that is repulsed by an eddy current induced in the secondary conductor of the carrier is generated, and the carrier is levitated on the track and transported.

[0003] Here, for example, due to the necessity of the layout of the manufacturing equipment, it is necessary to vertically move the carrier as well as vertically move the carrier. Conventionally, such raising and lowering of the carrier has been performed by an apparatus as shown in FIG. 7 or 8. The transporting device shown in FIG. 7 has track units 2A and 2A in which the tracks serving as the transport path of the transport base 1 are installed with steps.
The track unit 2B is composed of B and 2C, and the track unit 2B located between the track units 2A and 2C is moved up and down by the elevator apparatus 3, and is provided on the surface portion of each track unit 2A, 2B, and 2C. The amount of alternating current to the electromagnet 4 is constant,
The flying height of the carrier 1 on the track is always constant. In this transport device, for example, track unit 2
When the carrier 1 is to be lifted from A to the track unit 2C side and to be transported, the elevator unit 3 sets the track unit 2B at the same height as the track unit 2A, and the carrier 1 is magnetically levitated. After moving from 2A onto the orbital unit 2B and raising the orbital unit 2B to the same height as the orbital unit 2C by the elevator device 3, the carrier 1 on the orbital unit 2B is moved onto the orbital unit 2C by magnetic levitation. Let

The transport device shown in FIG. 8 has a track unit 6 in which the tracks serving as the transfer path of the transfer table 5 are installed with a step difference therebetween.
A robot 7 having a lifting / rotating function, which is composed of A and 6B, receives the carrier 5 (or only the object to be transported) from one track unit and transfers it to the other track unit between these track units. Each orbital unit 6A, 6
The amount of alternating current to the electromagnet 8 provided on the surface portion of B is constant, and the flying height of the carrier table 5 on the track is always constant. In this transfer apparatus, for example, when the transfer table 5 is to be moved from the track unit 6A to the track unit 6B side for transfer, the rotary table 9 of the robot 7 is set at the same height as the track unit 6A, and the transfer table is moved. 5 is moved from the track unit 6A onto the rotary table 9 and the rotary table 9 is raised to the same height as the track unit 6B.
The carriage 5 on the turntable 9 is moved onto the track unit 6B.

[0005]

In the conventional magnetic levitation transport apparatus as described above, since it has a mechanical lifting function portion such as the elevator apparatus 3 and the robot 7, scattering of dust and oil is possible. However, the advantage of the magnetic levitation transfer device, that is, the avoidance of a mechanical structure portion that is apt to occur, has not been fully exerted. Further, since it has a mechanical mechanism, it requires periodical maintenance management such as refueling and replacement of wear parts, which has increased the running cost of the magnetic levitation transport device.

The present invention has been made in view of the above-mentioned conventional circumstances. By fully utilizing the characteristics of the magnetic levitation transfer system, it is possible to effectively prevent the occurrence of contamination factors of the transferred object such as dust and oil scattering. Therefore, it is an object of the present invention to provide a magnetic levitation transfer device that can transfer an object to be transferred up and down in a clean state and further reduce the running cost of the device.

[0007]

SUMMARY OF THE INVENTION A magnetic levitation transport apparatus of the present invention comprises a carrier having at least a part thereof a secondary conductor made of a non-magnetic and good conductor, a track serving as a carrier path of the carrier, and a track. A large number of electromagnets arranged side by side in the longitudinal direction of the track on the surface part of the magnet and an alternating magnetic field is generated by passing an alternating current through the electromagnet, and the eddy current induced in the secondary conductor of the carrier is repulsed by the alternating magnetic field. In a magnetic levitation transfer apparatus including a control device for generating an alternating magnetic field to levitate the transfer table on the track, the track has a plurality of dimensions each longer than the length of the transfer table and connected to each other with steps. It is characterized in that it is composed of track units, and the control device can arbitrarily adjust the amount of alternating current supplied to the electromagnet.

[0008]

In the magnetic levitation transfer apparatus of the present invention, the controller adjusts the amount of the alternating current supplied to the electromagnet provided on the surface of the track so that the levitation amount of the transfer table is equal to or greater than the step of the continuous portion of the track unit. By sequentially lifting and lowering the carrier between the track units, the carrier is vertically lifted at the total height of each step. Furthermore, by adjusting the amount of alternating current based on the information from the position detector, accurate control according to the position of the carrier is performed.

The magnetic levitation transfer apparatus of the present invention can be used as a wafer transfer apparatus in a clean vacuum in a semiconductor manufacturing process, and for example, in a transfer apparatus under strict hygiene control of foods, in a high temperature or low temperature atmosphere. The present invention can be widely applied to various kinds of transfer devices such as the transfer device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the orbit of the magnetic levitation transport apparatus is constituted by connecting orbit units 11A, 11B, 11C and 11D, and these orbit units 11A, 11B and 1 are connected.
A step is formed at the connecting portion of 1C and 11D, and the positions are sequentially increased from the track unit 11A side to the track unit 11D. Each orbital unit 11A, 11B, 11C, 11D
A large number of electromagnets 12 are arranged side by side in the longitudinal direction of the track on the surface portion of each electromagnet 12, and each electromagnet 12 includes a magnetic pole 13 and an exciting coil 14 wound around the magnetic pole 13.

The exciting coil 14 of each electromagnet is a controller 15
The control device 15 controls the alternating current to supply power. A carrier 16 on which a carrier such as a wafer is placed and floated on a track is provided for each track unit 11A, 11A.
B, 11C, 11D has a dimension shorter than the length in the longitudinal direction (that is, each orbital unit has a dimension longer than the length of the carrier 16), and the carrier 16 has each orbital unit 11A, 11B, 11
It fits perfectly on C and 11D. Also,
Although the carrier table 16 is illustrated as a flat plate in the present embodiment, the carrier table 16 may be provided on at least a part thereof, such as a bottom surface part, even if the entire illustrated part is not a secondary conductor. It suffices to have a secondary conductor made of a non-magnetic and good conductor.

Each orbital unit 11A, 11B, 11C, 11
The position detector 1 is located above the entrance and exit of D, for example.
7, the position detector 17 detects the step between the track units or the carriage 16 approaching the entrance or exit of the track, and inputs position information about the carriage 16 to the controller 15. It has become. For example, a photoelectric sensor is used as the position detector 17, but another type of sensor may be used as long as the position of the carrier 16 can be detected.

Each orbital unit 11A, 11B, 11C, 11
A flying height detector 18 is provided above D, for example, and these flying height detectors 18 are used for the respective track units 11A and 11A.
The flying height of the carrier 16 above B, 11C, and 11D is detected, and information regarding the flying height of this carrier 16 is input to the control device 15. For example, a photoelectric sensor is used as the flying height detector 18, and the flying height is detected from the position of the surface of each track unit and the detected position of the carrier 16. However, if the flying height of the carrier 16 can be detected, other Types of sensors can also be used.

The control device 15 is capable of arbitrarily adjusting the amount of alternating current supplied to the exciting coil 14 of the electromagnet on the basis of information input from the position detector 17 and the flying height detector 18, and the alternating current power supply and control are possible. And a circuit portion. When a stationary alternating magnetic field is generated by causing an alternating current of the same phase to flow from the control device 15 to the electromagnet 12, a stationary alternating magnetic field repulsed by the eddy current induced in the carrier 16 is generated by this, and the carrier 16 is on orbit. Will surface. By applying an alternating current of different phase to the electromagnet 12,
When the moving alternating magnetic field is generated, the carrier table 16 travels according to the moving alternating magnetic field due to the principle of the linear induction motor.
Therefore, if the controller 15 arbitrarily adjusts the amount and phase of the alternating current supplied to the electromagnet 12, the flying height and the moving speed of the carrier 16 are adjusted accordingly.

According to the magnetic levitation transporting apparatus having the above structure, it is possible to transport the pedestal 16 while moving it up and down along the track as follows. First, as shown in FIG. 2, when the carriage 16 is floated and conveyed on the track unit 11A and its tip reaches the vicinity of the step of the track unit 11B, as shown in FIG. The amount of alternating current supplied to the coil 14 is increased to increase the alternating magnetic field, and the carrier table 16 is levitated above this step. Then, as shown in FIG. 4, the carrier 16 is moved in the horizontal direction to get over the step, and as shown in FIG. 5, the carrier 16 is moved onto the track unit 11B, thereby raising the carrier 16. While carrying. Here, in the state of overcoming the step shown in FIG. 4, the magnitude of the alternating magnetic field of both track units is adjusted so that the carrier 16 has the same height by the alternating magnetic field of either track unit 11A, 11B. . When carrying the carrier 16 while lowering it, the operation reverse to the above may be performed.

Although the above-mentioned transport operation changes the alternating magnetic fields of all the electromagnets 12 provided in one orbital unit, the electromagnets included in a range in which the orbital unit is divided into a plurality of units in the longitudinal direction by the control device 15. The AC current may be adjusted for each 12 and the magnitude of the alternating magnetic field (that is, the flying height of the carrier 16) may be different for each range even within one orbit unit.

Incidentally, as shown in FIG. 6, the object 19 to be carried in or out of the carrier 16 on the track is often carried out by the hand 21 of the robot 20 such as a process device. 21 cannot be raised or lowered,
When the heights of the hand 21 and the transported object 19 do not match, the control device 15 adjusts the magnitude of the alternating magnetic field of the electromagnet 12 and adjusts the floating amount of the transportation platform 16 so that the transported object 19 does not interfere. Can be carried in and out.

In the above embodiment, the orbital units are connected so that the orbits are inclined as a whole.
Depending on layout circumstances and the like, the orbital units may be connected to each other so that the orbital shape becomes a mountain shape as a whole.

[0020]

As described above, according to the magnetic levitation transportation apparatus of the present invention, the orbit is composed of a plurality of orbital units connected with a step, and the magnetic field of the electromagnet that gives the levitation force to the carrier is adjusted. By doing so, since the carrier is moved up and down on the track, it is possible to eliminate the mechanical lifting function part such as an elevator device or robot that easily causes dust and oil from scattering from the structure of the carrier device. It is possible to fully convey the advantages of the transfer device and transfer the transfer target in a clean state. Further, by eliminating the mechanical mechanism, it is possible to reduce the periodic maintenance management such as refueling and replacement of wear parts, and it is also possible to reduce the running cost of the magnetic levitation transport device.

[Brief description of drawings]

FIG. 1 is a side sectional view of a magnetic levitation transport device according to an embodiment of the present invention.

FIG. 2 is a sectional view for explaining the operation of the magnetic levitation transport device.

FIG. 3 is a sectional view for explaining the operation of the magnetic levitation transport device.

FIG. 4 is a cross-sectional view illustrating the operation of the magnetic levitation transport device.

FIG. 5 is a cross-sectional view illustrating the operation of the magnetic levitation transport device.

FIG. 6 is a configuration diagram illustrating an example of use of the magnetic levitation transport device.

FIG. 7 is a side sectional view of a conventional magnetic levitation transport device.

FIG. 8 is a side sectional view of a conventional magnetic levitation transport device.

[Explanation of symbols]

 11A, 11B, 11C, 11D Orbital unit 12 Electromagnet 13 Magnetic pole 14 Excitation coil 15 Control device 16 Conveyor stand 17 Position detector 18 Levitation amount detector 19 Conveyed object

Claims (4)

[Claims] 1. A carrier having at least a part thereof a secondary conductor made of a non-magnetic and good conductor, a track serving as a carrier path of the carrier, and a surface portion of the track being aligned in the longitudinal direction of the track. A large number of electromagnets arranged, and an alternating magnetic field is generated by flowing an alternating current through the electromagnets, and an alternating magnetic field repulsive by the eddy current induced in the secondary conductor of the carrier is generated thereby, and the carrier is In a magnetic levitation transfer apparatus including a control device for levitating the track on the track, the track is composed of a plurality of track units each having a dimension longer than the length of the transfer table and connected to each other with steps, Is a magnetic levitation transfer device characterized in that the amount of alternating current supplied to the electromagnet can be arbitrarily adjusted. 2. A position detector for detecting the position of the carrier for each track unit is provided, and the controller adjusts the amount of alternating current for each electromagnet included in the track unit based on the information from the position detector. The magnetic levitation transfer device according to claim 1. 3. A flying height detector for detecting the flying height of the carrier for each track unit, and the controller adjusts the amount of alternating current for each electromagnet included in the track unit based on information from the flying height detector. The magnetic levitation transport device according to claim 1, wherein 4. The magnetic levitation transfer device according to claim 1, wherein the control device adjusts the alternating current for each electromagnet included in a range obtained by dividing the track unit into a plurality of units in the longitudinal direction.