JP2006333652A - Linear motor and precision rotary table - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor and a precision rotary table that make it possible to, in industrial machines, such as semiconductor or liquid crystal processing equipment, requiring precise rotary indexing or alignment positioning, simplify their mechanisms and carry out precise rotary indexing and positioning. <P>SOLUTION: A pair of lower and upper magnets 11, 12 having partly arc shape simulating the peripheral end portion of a rotary table T are disposed as moving members 10 in fan shape at the peripheral end portion of the rotary table T. Coils portions 21 having the same partly arc shape are fixed as stators 20 on a machine fixed portion S so that they cut across the magnetic fields formed by the lower and upper magnets 11, 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention simplifies the mechanism and provides high-precision rotation indexing and positioning in an industrial machine that requires high-precision rotation indexing or alignment positioning, such as a linear motor and a precision rotary table, particularly a semiconductor or liquid crystal manufacturing apparatus. The present invention relates to a linear motor and a precision rotary table that are made possible.

  In the conventional rotary indexing machine, the table is driven by a motor coupled to the central axis of the table, and the table is driven by the rotation of the motor. While the motor drive direction and the table operation direction are both rotation directions, the table shape has been increased in size to improve the rotation indexing accuracy. As the table shape increases, the mechanical strength and rigidity of the shaft and joint are increased. The rotary indexing machine was large.

  The machine table has an appropriate rotary bearing (bearing) in order to hold the article to be processed accurately. Further, since the motor also has the same rotation bearing, the coupling portion needs a mechanism that absorbs mechanical interference due to misalignment between the central axes. For this reason, the rigidity of a drive part falls and it cannot position with high precision.

  Further, since the table drive of the machine is performed with the rotation center axis, a very high drive resolution is required for the motor when determining the position of the end side of the table with high accuracy. In addition, since the high inertia table is rotated by driving the central axis, a high torque is required for the motor.

  Further, even in the alignment operation in which the position correction operation in a minute range is performed in the positioning operation of the table, the motor drive is a full range operation, which is wasteful and high in cost. As an improvement measure, a method of driving a minute range with a linear actuator using a ball screw or the like that linearly drives the end of the table is used (see, for example, Non-Patent Document 1). However, adjustment is difficult due to the complicated mechanism. Further, since the driving force is in the rotational direction with respect to the linear direction, the control becomes complicated and it becomes difficult to ensure the rotation indexing accuracy.

“IKO Precision Alignment Table AT”, Nippon Thompson Corporation, [online], [Search May 19, 2005], Internet <URL: http: /www.ikont.co.jp/product/mecha/mch10.htm >

As described above, in order to perform highly accurate positioning in the conventional rotary indexing machine, the mechanical rigidity of the central axis must be increased, and thus the mechanism portion including the central axis is necessarily increased in size. Further, a mechanism and adjustment for avoiding interference between the rotary bearings due to misalignment of the machine and motor shafts are required. As a result, there is a problem that the cost increases and the mechanism including the coupling portion becomes complicated. Further, if the rotation of the large table is driven by the central axis, a large torque is required for the motor, and the motor becomes large. High-precision positioning driving requires a high-resolution sensor and high-resolution torque control. In addition, the motor that drives the central axis has a problem of poor work efficiency because it is driven all around even in a minute range drive.
On the other hand, the end driving by the linear actuator has a problem that it is difficult to ensure performance because the mechanism is complicated and the drive direction is different because the linearity of the control is lost.
Accordingly, the present invention has been made in view of the above-described problems of the prior art, and the problem to be solved requires a semiconductor or liquid crystal manufacturing apparatus, an inspection apparatus for determining rotation with high accuracy, or alignment positioning. An object of the present invention is to provide a linear motor and a precision rotary table that are used as drive motors in industrial machines, simplify the mechanism of the devices, and enable high-precision rotation indexing and positioning in the devices.

In a first aspect of the invention for achieving the above object, a coreless linear motor that generates an electromagnetic force by a mutual induction action of a field part and an armature part, wherein the field part is a rotating table to be driven. The rotor is disposed at an outer peripheral end portion, and the armature portion is fixed at a position crossing the magnetic field formed by the field magnet portion to become a stator, and the driving direction of the electromagnetic force corresponds to the rotation direction of the rotary table. It is characterized by being.
In the linear motor according to the first aspect of the invention, the field portion is disposed at the outer peripheral end portion of the rotary table and serves as the rotor, and the armature portion is fixed to the stator, so that the rotary table is driven at the outer peripheral end portion. The As a result, the rotary table can be driven with a small thrust. Thereby, in order to drive the rotary table, it is sufficient to drive a part of the outer peripheral end portion of the rotary table, so that work efficiency is increased. Furthermore, since the driving direction of the electromagnetic force corresponds to the rotating direction of the rotary table, in addition to improving the controllability of the rotary table, the rotary table to be driven has a center including the drive shaft. A coupling portion that couples the shaft and the drive shaft and a mechanism that absorbs mechanical interference due to misalignment of the shaft core and the like are unnecessary, which can contribute to simplification of the drive mechanism of the rotary table.

In a second aspect of the invention, the field portion has a pair of magnet portions that are in the shape of one partial arc simulating the outer peripheral end of the rotary table, and the armature portion is in the shape of the other partial arc. And having a coil portion that crosses the space between the pair of magnet portions.
In the linear motor according to the second aspect of the invention, both the magnet part of the field part and the coil part of the armature part have a partial arc shape simulating the outer peripheral end of the rotary table. The direction of the electromagnetic force acting on the field part coincides with the tangential direction of the rotary table, so that the rotational displacement of the rotary table with respect to driving has high linearity, and high-precision rotation indexing with respect to the rotary table to be driven and Allows rotational positioning.

In the third invention for achieving the above object, the rotary table, the linear motor of the first invention for driving the rotary table, the rotary position detecting means for detecting the position of the rotary table, and the rotary position And a control device that controls the driving of the linear motor based on detection information from the detection means, and enables highly accurate rotation indexing and rotation positioning with respect to the rotary table.
In the precision rotary table of the third invention, the linear motor that drives the rotary table has a linearity in which the rotary displacement of the rotary table with respect to the drive has high linearity. Therefore, the linear motor is driven by the rotary position detecting means and the control device. Highly accurate rotation indexing and rotation positioning with respect to the rotary table can be realized by suitably controlling. Further, since the linear motor drives the outer peripheral end of the rotary table, a small thrust is sufficient to drive the rotary table, and this precision rotary table has energy saving properties. Furthermore, the rotary table to be driven does not require a drive shaft, and a mechanism for absorbing mechanical interference due to misalignment of the center axis and the drive shaft and a shaft core are not required. The table drive mechanism is greatly simplified.

According to the linear motor of the present invention, the rotational displacement of the rotary table with respect to driving has high linearity. Further, since it is sufficient to drive a part of the outer peripheral end of the rotary table in order to drive the rotary table to be driven, a large torque is generated with a small thrust, and the work efficiency is increased.
Further, according to the precision rotary table of the present invention, high-precision rotary indexing and rotary positioning with respect to the rotary table are realized, energy saving is improved, and the rotary table drive mechanism is greatly simplified.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

FIG. 1 is an explanatory cross-sectional view of a main part showing an arc-shaped linear motor 100 according to an embodiment of the present invention.
This arc-shaped linear motor 100 includes a field element that forms a magnetic field, a mover 10 as a rotor, and an armature part that is energized to generate magnetomotive force and a stator 20 as a stator. It is configured.

  The mover 10 includes a lower magnet 11 that supplies magnetic flux to form a magnetic field, the upper magnet 12, a lower base 13 that supports the lower magnet 11, an upper base 14 that supports the upper magnet 12, It consists of a base fixing block 15 that fixes the lower base 13 and the upper base 14, and converts magnetic energy supplied from a coil portion 21 described later into kinetic energy such as rotation of the rotary table T, for example. The mover 10 is attached to the outer peripheral end of the turntable T, generates electromagnetic force in the tangential direction of the turntable T by electromagnetic induction action with the coil portion 21, and the electromagnetic force rotates the turntable T. Torque.

  Further, since the mover 10 is attached to the outer peripheral end of the turntable T, a large torque can be generated with a small electromagnetic force. Therefore, the conventional precision rotary indexing or positioning rotary table is a so-called center axis drive that rotates when the armature of the motor coupled coaxially with the center axis rotates, and as a result, a large torque However, since the arc-shaped linear motor 100 of the present invention is driven at the outer peripheral end, it can generate a large torque with a small current.

  Further, as will be described later, since this arc-shaped linear motor 100 is disposed as a part of the outer peripheral end portion of the rotary table, only a part of the outer peripheral end portion of the rotary table is driven. On the other hand, the motor for driving the conventional rotary table drives the entire circumference of the rotary table. Therefore, this arc-shaped linear motor 100 is excellent in work efficiency.

  The stator 20 is composed of a coil portion 21 as an armature around which a coil (not shown) is wound, and a coil fixing block 22 that supports the coil portion 21, and is fixed to the machine fixing portion S. Further, when a current flows through the coil portion 21, a magnetomotive force is generated, and a magnetic flux generated by the magnetomotive force penetrates the mover 10, thereby inducing an induced current in the mover 10. An electromagnetic force is generated in the movable element 10 due to the interaction between the induced current and the magnetic flux, and the electromagnetic force becomes a torque for rotating the rotary table T as described above.

It is explanatory drawing which shows the AA cross section of FIG. 2, FIG.
The lower magnet 11 has a partial arc shape simulating a part of the outer peripheral end portion of the turntable T, and is arranged in a fan shape along the arc of the outer peripheral end of the turntable T. The coil portion 21 has a partial arc shape that approximates the shape of the lower magnet 11 so as to overlap the lower magnet 11. The upper magnet 12 has the same shape as the lower magnet 11.

  By forming the lower and upper magnets 11 and 12 and the coil portion 21 in the shape of the above partial arc, it becomes possible to dispose them in a fan shape along the arc at the outer peripheral end of the turntable T. In the movable element 10, an electromagnetic force is generated in the tangential direction of the rotary table T, and the electromagnetic force becomes a torque for rotating the rotary table T.

  As a result, in the end drive with a ball screw for a conventional rotary table, the driving direction is a straight line, while the rotational direction is a circumferential direction, so it is difficult to perform high-precision rotation indexing and positioning control on the rotary table. In the motor 100, the rotation direction of the rotary table matches the drive direction, and the rotary displacement of the rotary table with respect to the drive has high linearity, so that highly accurate rotary indexing and positioning control with respect to the rotary table can be performed.

  As described above, according to the arc-shaped linear motor 100, the rotational displacement of the rotary table T with respect to driving has high linearity. Moreover, since it is sufficient to drive a part of the outer peripheral end of the rotary table T in order to drive the rotary table to be driven, a large torque is generated with a small electromagnetic force, and further, a desired rotational angle or rotational displacement is achieved. On the other hand, work efficiency becomes high.

  In the above embodiment, the mover 10 that is a field part is a rotor and the stator 20 that is an armature part is a stator. On the contrary, the mover 10 is a stator and is a machine fixing part S. It is also possible to provide an arc-shaped linear motor in which the stator 20 is fixed to the outer peripheral end of the rotary table T and is arranged in a fan shape along the arc.

FIG. 3 is an explanatory view showing a precision rotary table 200 according to another embodiment of the present invention.
The precision rotary table 200 includes a rotary table 1 on which processed parts and the like are placed and which can be rotated around a rotary shaft 2. A movable element 10 is arranged in a fan shape along an arc of the rotary table 1. Reference numeral 20 denotes an arc-shaped linear motor 100 attached to the machine fixing unit 3, a sensor scale 4 and a rotational position sensor 5 as rotational position detecting means for detecting the rotational position of the rotary table 1, and electrical signals from the rotational position sensor 5. And a control device 6 for controlling the positioning of the rotary table 1 by driving the arc-shaped linear motor 100 based on the above.

  The sensor scale 4 is attached to the outer peripheral end face of the turntable 1, and the rotational position sensor 5 has the same or similar arc shape as the sensor scale 4. The sensor scale 4 and the rotational position sensor 5 are preferably, for example, a photoelectric rotary encoder that does not involve mechanical contact.

  For example, the control device 6 detects the rotation amount of the turntable 1 from the detection information of the sensor scale 4 and the rotation position sensor 5 attached to the turntable 1, and an error between the rotation amount and a preset reference rotation amount. Is calculated, an operation amount based on the error is calculated, and the circular linear motor 100 is driven based on the operation amount to control the rotational position of the turntable 1 to be controlled, so-called feedback control is performed. .

  As described above, according to the precision rotary table 200, since the outer peripheral end is driven by the arc-shaped linear motor 100, the driving direction and the rotational direction of the rotary table 1 coincide with each other, and the rotational displacement of the rotary table 1 with respect to driving is high. Have sex. As a result, the loop gain of the feedback control can be increased, and the rotation table 1 can be subjected to highly accurate rotation indexing or rotation positioning control. In addition, the motor drive shaft, the connecting portion that connects the drive shaft and the table rotation shaft, and the interference mechanism that corrects the misalignment of the shaft center, which are indispensable in the conventional rotary indexing machine, are unnecessary, and the mechanism is greatly simplified. The Furthermore, since the rotary table 1 is driven at the outer peripheral end by the arc-shaped linear motor 100, energy saving is achieved.

  The linear motor and the precision rotary table of the present invention are suitably applied to semiconductor and liquid crystal manufacturing apparatuses, inspection apparatuses that determine rotation with high accuracy, or industrial machines that require alignment positioning.

It is principal part sectional explanatory drawing which shows the circular arc type linear motor which concerns on embodiment of this invention. It is explanatory drawing which shows the AA cross section of FIG. It is explanatory drawing which shows the precision rotary table which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary table 2 Rotating shaft 3 Machine fixing | fixed part 4 Sensor scale 5 Rotation position sensor 6 Control apparatus 10 Movable element 20 Stator 100 Arc type linear motor 200 Precision rotary table

Claims (3)

  A coreless linear motor that generates electromagnetic force by a mutual induction action of a field part and an armature part, wherein the field part is disposed at an outer peripheral end of a rotary table to be driven and serves as a rotor, and the electric machine The child part is fixed at a position crossing the magnetic field formed by the field part and becomes a stator, and the driving direction of the electromagnetic force corresponds to the rotation direction of the rotary table.   The field portion has a pair of magnet portions that are in the shape of one partial arc simulating the outer peripheral end of the rotary table, and the armature portion is in the shape of the other partial arc and the pair of pairs The linear motor according to claim 1, further comprising a coil portion that crosses a space sandwiched between the magnet portions.   The rotation table, the linear motor according to claim 1 that drives the rotation table, a rotation position detection unit that detects a position of the rotation table, and detection information from the rotation position detection unit A precision rotary table comprising a control device for controlling driving and enabling highly accurate rotary indexing and rotary positioning with respect to the rotary table.

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