JP2010207938A - Substrate transfer robot having multistage motor as drive source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate transfer robot having a multistage concentric motor as a drive source, which has a small detector in the motor, can ensure a high level of arm controllability and can realize easy replacement of the detector. <P>SOLUTION: The substrate transfer robot includes a drive having a first rotary motor 13 and a second rotary motor 14 for driving a robot arm disposed axially in a multistage manner. A rotary position detector in the first rotary motor 13 includes a first incremental encoder head 21 and rotational angle sensors 25a, 25b as absolute value position detectors of which the rotational position detection accuracy is lower than that of the first incremental encoder head 21. The rotary position detector in the second rotary motor 14 includes a second incremental encoder head 22 and rotational angle sensors 26a, 26b as absolute value position detectors of which the rotational position detection accuracy is lower than that of the second incremental encoder head 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate transfer robot for transferring a substrate such as a semiconductor wafer, and more particularly to a robot whose arm is driven by a multi-stage motor.

  2. Description of the Related Art In a semiconductor or liquid crystal manufacturing apparatus or inspection apparatus, a substrate transfer robot has been conventionally used to transfer a substrate such as a semiconductor wafer, a mask, or liquid crystal glass to a predetermined position. Part of the manufacturing process of semiconductors and liquid crystals is often performed in a decompressed space in the vacuum chamber, and the substrate transfer robot is required to operate in the vacuum chamber. The substrate transfer robot usually has a plurality of arms connected in the horizontal direction, and rotationally drives them to move the end effector installed at the tip of the arm to a desired position. The end effector is configured to hold the substrate. In many cases, a drive source of a substrate transfer robot that operates in a vacuum chamber is provided with motors that directly drive a plurality of arms in a so-called body portion in multiple stages on concentric shafts. This is mainly because each arm can be driven directly, so that high-precision control can be obtained, and because it is not necessary to use a sealing member such as a magnetic fluid seal, it is easy to obtain a high vacuum degree of the vacuum chamber. That is why. A substrate transfer robot using such multi-stage concentric motors is disclosed in, for example, Patent Document 1.

Since the vacuum chamber is depressurized from the atmospheric pressure, it is firmly manufactured to withstand the pressure due to the differential pressure. In many cases, the view port for monitoring the inside of the vacuum chamber is installed to the minimum. Even if a substrate transfer robot built into a device such as a vacuum chamber that cannot be checked visually is brought out of control and stopped due to unforeseen circumstances, the arm can be operated without contacting the surrounding obstacles, and a normal posture can be obtained. Must be able to recover. For this purpose, it is necessary to incorporate an encoder of an absolute value type instead of an incremental type in a position detector of a motor for driving and controlling the arm.
Therefore, a substrate transfer robot having a multistage concentric motor as a drive source for an arm has an absolute value rotational position detector manufactured to withstand it even in a vacuum environment. It is incorporated in the vicinity. For example, FIG. 1 of Patent Document 1 discloses that as many absolute value rotational position detectors are installed as the number of motors. Normally, each arm of the vacuum substrate transfer robot can often perform the necessary work by an operation within 360 degrees in the vacuum chamber. Therefore, the absolute value rotation position detector disclosed in Patent Document 1 is one rotation of the motor. It is intended to detect within. Therefore, if each arm is rotated 360 degrees or more, it is necessary to count the number of rotations of the motor, and a counter for that purpose and an auxiliary power source for maintaining the information when the power source is shut off are provided. A circuit board or the like is installed.

JP 2007-325433 A

However, it is not ideal to simply incorporate a vacuum-designed absolute value rotational position detector specially designed as described above into a part of the multistage concentric motor of the substrate transfer robot. This is because the drive unit of the substrate transfer robot is enlarged, and the increase in the drive unit leads to an increase in the capacity of the vacuum chamber. As the capacity of the vacuum chamber increases, it becomes difficult to maintain and achieve the desired degree of vacuum. Therefore, the detection part of the multistage concentric motor must be made as small as possible.
Also, in order to obtain a high control performance of the arm, the encoder needs to have a higher resolution, but the absolute value type detector has a lower resolution than that of the incremental type and obtains a high control performance. It is difficult.
In addition, the arrangement and configuration of the detectors in Patent Document 1 have a problem in that it is not easy to replace the detector when the detection unit fails, and the replacement cannot be performed unless the drive unit of the substrate transport robot is disassembled. That is, it is necessary to easily replace the detector of the substrate transfer robot.
The present invention has been made in view of such problems, and even in a substrate transfer robot having a multistage concentric motor as a drive source, the motor detection unit is small, and the arm has high control performance. An object of the present invention is to provide a substrate transfer robot that can be secured and in which a detection unit can be easily replaced.
It is another object of the present invention to provide a substrate transfer robot that does not require an auxiliary power source even though the detection is possible even when the motor rotates many times.

In order to solve the above problem, the present invention is configured as follows.
According to the first aspect of the present invention, in the substrate transfer robot having a drive unit in which at least two or more rotary motors for driving the robot arm are arranged in multiple stages in the axial direction, each rotational position of the rotary motor is detected. The portion includes an incremental position detector, and an absolute value position detector having a rotational position detection accuracy coarser than that of the incremental position detector.
According to a second aspect of the present invention, the absolute value position detector is fixed to a rotating disk that rotates together with the output shaft of the rotary motor, and is a ring magnet magnetized in the radial direction of the output shaft; 2. The substrate transfer robot according to claim 1, further comprising: a rotation angle sensor that detects the ring-shaped magnet and obtains a sine wave two-phase signal.
The invention according to claim 3 is the substrate transfer robot according to claim 2, wherein the rotation angle sensor is fixed to a sensor holder that can be inserted and removed from an external frame of the drive unit. .
According to a fourth aspect of the present invention, in the substrate according to the third aspect, the sensor holder is fixed to the outer frame via a sealing material for maintaining the airtightness of the outer frame of the driving unit. This is a transfer robot.
The invention according to claim 5 is characterized in that two of the rotation angle sensors are arranged so as to be opposed to the output shaft by 180 ° with the ring-shaped magnet interposed therebetween. The substrate transport robot according to claim 1 is used.
According to a sixth aspect of the present invention, the incremental position detector includes an incremental encoder scale attached to a rotating disk that rotates together with the output shaft of the rotary motor, an incremental encoder head that detects the incremental encoder scale, The substrate transport robot according to claim 1, comprising:
The invention according to claim 7 is the substrate transfer robot according to claim 6, wherein the incremental encoder head is fixed to a sensor holder that can be inserted and removed from an external frame of the drive unit. .
The invention according to claim 8 is the substrate according to claim 7, wherein the sensor holder is fixed to the outer frame through a sealing material for maintaining airtightness of the outer frame of the driving unit. This is a transfer robot.
The invention according to claim 9 is characterized in that the absolute value position detector includes a main driving magnetic gear that rotates together with an output shaft of the rotary motor, a driven gear having a diameter n times that of the main driving magnetic gear, 2. The substrate according to claim 1, comprising a magnet that rotates together with the driven gear and is magnetized in the radial direction of rotation, and a rotation angle sensor that detects the magnet and obtains a sine wave two-phase signal. This is a transfer robot.
A tenth to thirteenth aspect of the present invention is a semiconductor or liquid crystal manufacturing / inspection apparatus including the substrate transfer robot according to the first aspect.

As described above, according to the present invention, a relatively coarse absolute value position detection and a high-resolution incremental encoder can be incorporated into a concentric robot having two or more output shafts, and a robot main body that is short in the axial direction can be configured. Even if the robot stops due to unforeseen circumstances, use the absolute position detection function to recognize the robot's posture and return the robot arm to a normal state without making contact with surrounding interference. It is possible to shorten the time until the apparatus is restored and minimize the decrease in productivity. Further, in a robot that controls the hollow shaft side with multiple rotations, it is possible to detect multi-rotation absolute value position detection without an auxiliary power supply.

The internal block diagram of the robot for board | substrate conveyance which shows 1st Example of this invention Explanatory drawing which shows the position detector by the side of the 1st rotation motor of 1st Example. Explanatory drawing which shows the position detector by the side of the 2nd rotary motor of 1st Example. Signal processing block diagram for detecting the absolute value rotation angle within one rotation Explanatory drawing which shows the position detector which measures the motor rotation angle in n rotation of 2nd Example. Signal processing block diagram for detecting an absolute value rotation angle within n rotations

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a side section of the internal structure of a substrate transfer robot 1 having a concentric biaxial motor as a drive source to which the present invention is applied. The substrate transfer robot 1 is installed on the bottom surface of the vacuum chamber 40 via a robot mounting flange 39 or the like. The robot body 2 has a bucket shape, and the inside of the robot body 2 communicates with the vacuum chamber 40. That is, the inside of the robot body 2 can be brought into a decompressed state together with the vacuum chamber 40. The robot body 2 accommodates a plurality of rotary motors that serve as drive sources for the arms, which will be described later. In the case of the present embodiment, the first rotary motor 13 and the second rotary motor 14 are accommodated. The second motor output shaft 16 of the rotary motor 14 has a multistage configuration that passes through the hollow interior of the first motor hollow output shaft 15 of the first rotary motor 13.
In the present embodiment, the arm portion of the substrate transfer robot 1 includes a first arm 3, a second arm 4, and an end effector 5. The second arm 4 is rotatably supported at the tip of the first arm 3, and the end effector 5 is rotatably supported at the tip of the second arm 4. A substrate is placed on the end effector 5.
The base end of the first arm 3 is directly connected to the hollow output shaft 15 and is directly driven to rotate by the first rotary motor 13. The output shaft 16 of the second rotary motor 14 is connected to a first pulley 6 provided inside the base end side of the first arm 3 and rotationally drives it. The rotation is transmitted to the second pulley 7 provided in the front end side of the first arm 3 through the first belt 11 wound around the first pulley 6, and the second pulley 7 and the base end side are connected to each other. The connected second arm 4 is rotationally driven. Furthermore, the ratio of the third pulley 8 fixed inside the proximal end of the second arm 4 via the shaft 10 fixed inside the distal end side of the first arm 3 and the rotation inside the distal end side of the second arm 4 are possible. The end effector 5 is relatively driven to rotate so that the end effector 5 faces a desired constant direction by the ratio of the fourth pulley 9 fixed to the second pulley 12 and the second belt 12 wound around these.

Next, the rotational position detectors of the first rotary motor 13 and the second rotary motor 14 will be described. As shown in FIG. 2, in the present embodiment, the rotational position detectors of the first rotary motor 13 and the second rotary motor 14 are mounted at the lower part of each motor.
First, for the first rotary motor 13, a thin ring-shaped first rotary disc 17 is fixed to the lower end of the first motor hollow output shaft 15. The first rotary disk 17 is located between the upper and lower sides of the first rotary motor 13 and the second rotary motor 14. A ring-shaped first ring-shaped magnet 23 magnetized in the radial direction is fixed to the first rotating disk 17. On the other hand, a stick-shaped first sensor holder 31 is fixed from the external frame of the robot body 2 toward the center thereof. In the present embodiment, two first sensor holders 31 are mounted on the robot body 2. A rotation angle sensor 25 is fixed to each tip of the first sensor holder 31. The rotation angle sensor 25 is fixed to the first sensor holder 31 so that its detection part faces the outer peripheral surface of the first ring magnet 23. The rotation angle detection sensor is a general arrangement in which two magnetoresistive elements such as MR elements and Hall elements are bridge-connected and mechanically provided with a 90 ° angle difference with respect to the magnetizing direction of the magnet. Sensor can be used. Further, the two rotation angle sensors 25a and 25b are fixed by the first sensor holder 31 so as to face each other by 180 ° with the first ring-shaped magnet 23 interposed therebetween. The first sensor holder 31 is fixed via a seal member (not shown) so that it can be inserted and removed from the outside of the robot body 2 and the airtightness of the robot body 2 can be maintained.
That is, as shown in FIG. 2, the absolute value rotation angle detection within one rotation of the first rotary motor 13 is detected in the first ring magnetized in the radial direction of the ring shape attached to the lower end of the first motor hollow output shaft 15. A ring-shaped magnet 23 and rotation angle sensors 25a and 25b arranged to face the outer periphery of the magnet 23 so as to face the outer periphery of the magnet 23 obtain a sine wave two-phase signal detection with a phase difference of 90 °. Find the absolute rotation angle of. The two rotational angle sensors 25 are arranged for the purpose of improving the accuracy of rotational angle detection for correcting eccentricity of the rotating magnet, but it is preferable to arrange two or more rotational angle sensors 25.

Next, the second rotary motor 14 will be described. The basic configuration of the rotational position detector is substantially the same as that of the first rotary motor 13. Regarding the second rotary motor 14, a thin plate-shaped second rotary disk 18 is fixed to the lower end of the second motor output shaft 16. The second rotating disk 18 is located below the second rotating motor 14. A second ring-shaped magnet 24 that is ring-shaped and magnetized in the radial direction is fixed to the second rotating disk 18. On the other hand, the second sensor holder 32 is fixed from the bottom surface of the external frame of the robot body 2. The second sensor holder 32 may be supported from the side of the outer frame of the robot body 2 like the first sensor holder 31. In the case of the present embodiment, two second sensor holders 32 are mounted on the robot body 2. A rotation angle sensor 26 is fixed to each of the second sensor holders 32. The rotation angle sensor 26 is fixed to the second sensor holder 32 so that its detection part faces the outer peripheral surface of the second ring magnet 24. The rotation angle detection sensor is a general arrangement in which two magnetoresistive elements such as MR elements and Hall elements are bridge-connected and mechanically provided with a 90 ° angle difference with respect to the magnetizing direction of the magnet. Sensor can be used. Further, the two rotation angle sensors 26 a and 26 b are fixed by the second sensor holder 32 so as to face each other by 180 ° with the second ring magnet 24 interposed therebetween. The second sensor holder 32 is fixed via a seal member (not shown) so that it can be inserted and removed from the outside of the bottom surface of the robot body 2 and the airtightness of the robot body 2 can be maintained.
That is, as shown in FIG. 3, the absolute rotation angle within one rotation of the second rotary motor 14 is detected by the magnet 24 (shaped in a ring shape) that is attached to the second motor output shaft 16 in the radial direction. The rotation angle sensors 26a and 26b arranged to face the outer periphery of the magnet 24 so as to oppose the outer periphery of the magnet 24 are used to obtain a sine wave two-phase signal detection with a phase difference of 90 ° and perform absolute rotation. Find the corner. For the reason described above, two rotation angle sensors are arranged, but one may be used.

  Further, the first and second encoder scales 19 and 20 of the rotary incremental encoder are mounted on the outer peripheries of the respective rotary disks 17 and 18 described above. Further, the incremental encoder heads 21 and 22 are fixed so that the respective scales can be read. Each of the incremental encoder heads 21 and 22 is fixed to an incremental encoder sensor holder 33. The incremental encoder sensor holder 33 can be inserted / removed from the outside of the robot body 2 and is fixed via a seal member (not shown) so that the airtightness of the robot body 2 can be maintained. Note that these incremental encoders use a high-resolution encoder so that each arm can obtain a desired controllability.

FIG. 4 is a signal processing block diagram for detecting an absolute value rotation angle within one rotation in the rotation position detection unit configured as described above. The signals from the rotation angle sensors 25a (26a) and 25b (26b) capable of detecting rotation angles up to 360 ° and the signal 21 (22) from the high-resolution incremental encoder head are used as an absolute value rotation angle calculator 35a within one rotation. (36b), a rotation angle signal with coarse accuracy within one rotation of the motor and an angle signal with high resolution are obtained.
When the substrate transfer robot stops due to the initial startup of the vacuum substrate transfer robot or due to unforeseen circumstances, first, signals from the rotation angle sensors 25a (26a) and 25b (26b) having coarse absolute value detection accuracy are used. Each of the output shafts of the motor, that is, the posture of the arm is detected and returned to the initial state of the arm. The initial state of the arm is an origin posture stored in advance. After returning to the initial state, the control is switched to the signal from the high-resolution incremental encoder head 21 (22), and once reset by the origin signal of this incremental encoder, the normal arm is received by this highly accurate incremental encoder signal. If the posture control is performed, the arm posture control can be usually performed with high accuracy by the signal of the incremental encoder, and the rotation angle sensor 25 a ( 26a) and 25b (26b) can be used to safely return the arm to its initial state. Further, in the rotational position detection unit, even if a failure occurs in each sensor, these can be inserted and removed from the outside of the robot body 2 and exchanged.
As described above, in this embodiment, an absolute value type angle detector can be incorporated in a motor having two or more concentric shafts configured by arranging motors in multiple stages, and the size of the motor body in the output shaft direction can be shortened. In addition, the angle detector can be easily attached and detached. As a result, the substrate transport robot body can be downsized, and the detector can be replaced without disassembling the substrate transport robot body.

Next, a configuration that enables detection of the rotational position even when the output shaft of each motor, that is, each arm rotates multiple times, will be described as a second embodiment.
For example, if the second rotary motor 14 is driven at twice the number of rotations, the command can be issued at a substantially double rotation angle, so that arm position control can be further improved. In this case, the absolute value position detection within two rotations is performed by providing a magnetic gear 27 on the second motor output shaft 16 or the second rotating disk 18 of the second rotating motor 14 as shown in FIG. Rotation is transmitted to the driven magnetic gear 28 having a diameter twice as large as that of the second rotary motor 14 with a circular magnet 29 that rotates together with the driven magnetic gear 28, for example. Like that. In this case, the driven magnetic gear 28 is rotatably supported inside the frame of the robot body 2. The circular magnet 29 is magnetized in the radial direction, and a sine wave two-phase signal detection with a phase difference of 90 ° is obtained by rotation angle sensors 30a and 30b arranged to face and oppose the outer periphery of the magnet 29 by 180 °. Find the rotation angle. Two rotational angle sensors are arranged, but one may be used. FIG. 6 is a signal processing block for detecting an absolute value rotation angle within n rotations. Also in this embodiment, the rotation angle sensor 30 is detachable from the outside of the robot body 2.
In addition, the same incremental encoder 22 as the first embodiment and its scale 20 are provided on the outer peripheral portion of the second rotating disk 18.

  As described above, in this embodiment, for detecting the rotation angle of one or more rotations, the driven gear having a diameter n times the diameter of the main driving gear rotating together with the detected motor output shaft is rotated in a non-contact manner. The rotation angle up to n rotations of the shaft can be detected as an absolute value by a rotation angle sensor. In addition, it is possible to eliminate the need for an auxiliary power source for maintaining the multi-rotation amount of the motor.

DESCRIPTION OF SYMBOLS 1 Substrate conveyance robot 2 Robot main body 3 1st arm 4 2nd arm 5 End effector 6 1st pulley 7 2nd pulley 8 3rd pulley 9 4th pulley 10 Shaft 11 1st belt 12 2nd belt 13 1st rotation motor 14 Second rotary motor 15 First motor hollow output shaft 16 Second motor output shaft 17 First rotary disc 18 Second rotary disc 19 First encoder scale 20 Second encoder scale 21 First incremental encoder head 22 Second incremental Encoder head 23 First ring magnet 24 Second ring magnets 25a, 25b Rotation angle sensors 26a, 26b Rotation angle sensor 27 Drive magnetic gear 28 Driven magnetic gear 29 Circular magnets 30a, 30b Rotation angle sensor 31 First sensor holder 32 First 2 Sensor holder 33 Incremental encoder sensor Holder

35 1-rotation absolute value angle calculator 36 n-rotation absolute value angle calculator

39 Robot mounting flange 40 Vacuum chamber

Claims (13)

In a substrate transfer robot having a drive unit in which at least two or more rotary motors for driving a robot arm are arranged in multiple stages in the axial direction,
Each rotational position detector of the rotary motor is
A substrate transfer robot, comprising: an incremental position detector; and an absolute value position detector having a rotational position detection accuracy coarser than that of the incremental position detector. The absolute value position detector is
A ring-shaped magnet fixed to a rotating disk that rotates together with the output shaft of the rotary motor, and magnetized in the radial direction of the output shaft;
A rotation angle sensor that detects the ring-shaped magnet and obtains a sinusoidal two-phase signal;
The substrate transfer robot according to claim 1, comprising:   3. The substrate transfer robot according to claim 2, wherein the rotation angle sensor is fixed to a sensor holder that can be inserted and removed from an external frame of the drive unit.   4. The substrate transfer robot according to claim 3, wherein the sensor holder is fixed to the outer frame through a sealing material for maintaining airtightness of the outer frame of the driving unit.   5. The substrate transfer robot according to claim 2, wherein two rotation angle sensors are arranged to face the output shaft at 180 ° with the ring-shaped magnet interposed therebetween. The incremental position detector is
An incremental encoder scale affixed to a rotating disk that rotates with the output shaft of the rotary motor;
An incremental encoder head for detecting the incremental encoder scale;
The substrate transfer robot according to claim 1, comprising:   The substrate transfer robot according to claim 6, wherein the incremental encoder head is fixed to a sensor holder that can be inserted and removed from an external frame of the drive unit.   8. The substrate transfer robot according to claim 7, wherein the sensor holder is fixed to the outer frame via a seal material for maintaining airtightness of the outer frame of the driving unit. The absolute value position detector is
A main magnetic gear that rotates together with the output shaft of the rotary motor;
A driven gear having a diameter n times that of the main magnetic gear;
A magnet that rotates with the driven gear and is magnetized in the radial direction of rotation;
A rotation angle sensor that detects the magnet and obtains a sinusoidal two-phase signal;
The substrate transfer robot according to claim 1, comprising:   A semiconductor manufacturing apparatus comprising the substrate transfer robot according to claim 1.   A liquid crystal manufacturing apparatus comprising the substrate transfer robot according to claim 1.   A semiconductor inspection apparatus comprising the substrate transfer robot according to claim 1.   A liquid crystal inspection apparatus comprising the substrate transfer robot according to claim 1.

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