JP2013093396A - Arm type conveyance apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arm type conveyance apparatus in which a center position of a conveyance subject can be detected without conveying the conveyance subjects, one by one, to an aligner or the like which is installed at any other place than the arm type conveyance apparatus.SOLUTION: An arm type conveyance apparatus comprises an arm mechanism 2, an edge detection section 3, a rotation angle detection section 27 and a center position calculation section 41. In the arm mechanism 2, a first link 21 for holding a perfectly circular conveyance subject W is mounted through a rotary shaft C1 to a second link 22 that is a base member in a rotatable manner within a horizontal plane. The edge detection section 3 is mounted to the second link 22 together with the rotary shaft C1 and detects that an edge of the perfectly circular conveyance subject W is located at a detection position Se which is determined in accordance with a mount position. The rotation angle detection section 27 detects a rotation angle θ of the first link 21 with respect to the second link 22. The center position calculation section 41 calculates a center position of the perfectly circular conveyance subject W with respect to the link 21 on the basis of the corresponding rotation angle θ which is detected by the rotation angle detection section 27 when the edge of the perfectly circular conveyance subject W passes through the edge detection section 3.

Description

  The present invention relates to an arm-type transfer device having a rotatable link, and more particularly to an arm-type transfer device with an optimized function for detecting the center position of a regular circular transfer object such as a wafer and correcting a positional deviation.

  2. Description of the Related Art A conveyance device that conveys a thin circular object such as a semiconductor wafer according to a manufacturing process is known. Among them, a plurality of links are connected in series via a joint portion so as to be rotatable, and each joint portion is rotationally driven, so that one piece of transport object is stored from a storage case that stores the transport target object at a predetermined pitch. There is an arm type conveying device that takes out and conveys each one.

  When a regular circular conveyance object is conveyed to a processing apparatus, a general conveyance system uses a device called an aligner to correct the positional deviation of the regular circular conveyance object and convey the conveyance object properly. The alignment is performed. The alignment is performed in three directions: the X and Y directions and the θ direction of the aligner rotation axis.

  Japanese Patent Application Laid-Open No. 2004-133620 discloses a method for detecting the displacement in the X and Y directions and the θ direction as a means for aligning a regular circular conveyance object.

JP-A-8-222611

  However, according to the method disclosed in Patent Document 1, the center position of the circular object to be transported can be detected only on an aligner installed at a location different from the arm-type transporter during transport. When transporting a circular object, once the circular object is transported to the aligner, aligned, and then removed and transported to the target location. There is a problem that it takes time to align with the conveyance time.

  In addition, the general aligner including Patent Document 1 corrects the deviation detected by the starting shafts provided in the X and Y directions and the rotation direction after detecting the amount of positional deviation in each direction. On the other hand, three drive shafts had to be provided, and there was a problem that the cost was high.

  The present invention solves such a problem, makes it possible to detect the center position of a regular circular transport object in a short time, and based on the detected center position of the regular circular transport object, An object of the present invention is to provide an arm-type transfer device that determines the displacement of an object.

  In order to achieve this object, the present invention takes the following measures.

  That is, the arm-type transfer device according to the present invention includes an arm mechanism in which a link that holds a circular transfer object is attached to a base member so as to be rotatable in a horizontal plane via a rotation shaft, and the base member includes the arm mechanism. An edge detection unit that detects that the edge of the right circular conveyance object is positioned at a detection position that is attached together with the rotation shaft and is determined according to the attachment position; and a rotation angle detection unit that detects a rotation angle of the link with respect to the base member; Center position calculation for calculating the center position of the circularly circular conveyance object with respect to the link based on the corresponding rotation angle detected by the rotation angle detecting unit when the edge of the circularly circular conveyance object passes through the edge detection unit It comprises the part.

  With this configuration, the position of the object to be transported can be transported one by one to an aligner or the like installed separately from the arm-type transport device simply by passing the link holding the object to be transported in a circular shape through the edge detection unit of the base member. There is no need for alignment, and the center position coordinates of the circular object can be calculated from the rotation angle detection unit and the center position calculation unit, greatly reducing the time required for conveyance and alignment and greatly increasing costs. Can be reduced.

  Further, in order to determine the position deviation from the center position coordinate where the regular circular conveyance object should be originally, the position deviation of the regular circular conveyance object is detected based on the center position calculated by the center position calculation unit. A center position deviation determination unit is provided, and the center position deviation determination unit calculates the center position calculation unit for a reference center position given in advance and a circular object to be measured placed on a link to be measured. It is preferable that the center position deviation from the reference center position to the actual center position is determined based on the actual center position at the time.

  According to the present invention described above, just passing the circular object to be conveyed through the edge detection unit provided on the link base end side, the sheet is conveyed one by one to the aligner and the like, and the alignment of the circular object is performed. Even without this, since the center position coordinates of the circular object to be transported can be calculated, the time for transport and alignment can be greatly reduced, and the cost can be greatly reduced.

The perspective view which shows the arm which concerns on one Embodiment of this invention. The perspective view which shows operation | movement of the arm type conveying apparatus. The expansion perspective view which shows the edge detection part of the same arm. The top view which shows typically operation | movement of the arm. The xy coordinate diagram which shows the relationship between the edge and center position of a perfect circular conveyance target object after finishing passing an edge. The schematic diagram which shows the motion of the perfect circular conveyance target object at the time of link rotation. Explanatory drawing for demonstrating the function which determines the center position shift of a perfect circular conveyance target object.

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

The arm type transfer device of the present embodiment is of a robot arm type, and as shown in FIGS. 1 and 4, a first effector called an end effector that holds a circular transfer object W such as a disk-shaped semiconductor wafer. A plurality of links 21, 22, and 23 including links 21 are held by the first link 21 and the arm mechanism 2 that is configured to be pivotably connected in a horizontal plane via joint portions 24, 25, and 26. The edge detection unit 3 for detecting the edge of the regular circular conveyance object W and the rotation drive of each joint portion 24, 25, 26 in the arm mechanism 2 are controlled by the first link 21. And a control unit 4 that transports the circular object W to a desired position.

  As shown in FIGS. 1 and 4, the arm mechanism 2 includes a first link 21 that holds the circular object to be conveyed W on the distal end side, and a base end portion 21 b of the first link 21 on the distal end portion 22 a in a horizontal plane. A second link 22 that is pivotably connected within, a third link 23 that is pivotally connected to a distal end portion 23a in a horizontal plane with a base end portion 22b of the second link 22, and a third link. And a base 20 that rotatably supports a base end portion 23b of the base plate 23 in a horizontal plane. The first link 21 is substantially Y-shaped and plate-shaped in plan view, and a stepped portion 21c having a shape corresponding to the periphery of the regular circular conveyance object W is formed on the upper surface. The step portion 21c is a mounting surface on which the conveyance object is placed, and exhibits a function of holding the conveyance object by being formed lower on the inner circumferential side than on the outer circumferential side. The proximal end portion 21b of the first link 21 and the distal end portion 22a of the second link 22 are connected to each other so as to be rotatable in a horizontal plane around the rotation axis C1 along the vertical direction. It is composed. Similarly, the proximal end portion 22b of the second link 22 and the distal end portion 23a of the third link 23, the proximal end portion 23b of the third link 23, and the base 20 are also rotational axes C2 along the vertical direction. The second joint portion 25 and the third joint portion 26 are configured to be pivotable within a horizontal plane around C3. Each of the joint portions 24, 25, and 26 is configured to be able to change the angle θ of each link 21, 23, and 24 by being driven to rotate independently of the other joint portions by a power unit M using a motor or the like. (See FIG. 4).

  The control unit 4 is composed of a normal microcomputer unit having a CPU, a memory, and an interface, and stores a program for outputting a control signal to each motor. The CPU reads and executes this program as appropriate. Then, the regular circular conveyance object W held by the first link 21 is conveyed to the target position.

  In such control, when the center position of the circular object W is deviated from the normal position on the first link 21 that is the end effector, the tip of the first link 21 is moved along the required trajectory. Even if it is moved to the target position, a situation occurs in which the circular object W is not transferred to the target position.

  Therefore, the present embodiment further includes an edge detection unit 3 for detecting the edge of the regular circular conveyance object W held by the first link 21 in order to detect the center position of the regular circular conveyance object W; A rotation angle detector 27 such as an encoder for detecting the rotation angle of the first link 21, and a center position for calculating the center position of the regular circular conveyance object W based on the detection values in these detectors 3 and 27 A calculation unit 41 and a center position deviation determination unit 42 that determines a deviation from the center position based on the center position coordinates obtained by the center position calculation unit 41 are provided.

  As shown in FIG. 3, the edge detection unit 3 for detecting the edge of the regular circular conveyance object W is a detection position Se corresponding to the mounting position, such as a photoelectric sensor including a light emitting element 30 and a light receiving element 31. The edge of the regular circular conveyance object W is detected, and the circular conveyance object W passes through the detection position Se, which is a light path connecting the light emitting element 30 and the light receiving element 31, and the light receiving element 30 receives the light receiving element. The edge of the circular object to be conveyed W is detected according to whether or not the light traveling toward 31 is blocked. As shown in FIGS. 1 to 4, the edge detection unit 3 is a base member that is a base member on the proximal end side of the first link 21 among the plurality of links 21, 22, and 23 constituting the arm mechanism 2. As shown in FIGS. 2 and 4, the first link 21 is attached in the direction in which the first link 21 approaches the second link 22 to which the edge detection unit 3 is attached. The mounting position of the edge detection unit 3 is set so that the edge of the right circular conveyance object W can be detected by passing through the detection position Se on the first link 21 when the joint portion 24 is rotated. The data is output to the control unit 3 as a signal S1. Furthermore, the mounting position of the edge detection unit 3 is set so as not to interfere with the plurality of links 21, 22, and 23 when the joint units 24, 25, and 26 are rotationally driven. That is, it can be said that the edge detection unit 3 is attached at a position that avoids the rotation trajectory of each of the links 21, 22, and 23.

  Further, in FIG. 2, the rotation angle detection unit 27 is provided at the distal end portion 22a of the second link 22 on the proximal end side in order to rotationally drive the first link 21 that holds the circular object to be conveyed W. The rotation angle of the first link 21 with respect to the second link 22 is detected and the data is sent to the control unit 4 as a signal E1 as shown in the block diagram at the upper left of FIG. Output.

  The center position calculation unit 41 passes the regular circular conveyance object W through the edge detection unit 3 while rotating the first link 21 with respect to the second link 22, and thereby the regular circular conveyance object W. The center position of is detected.

  The center position calculation unit 41 is configured by the following calculation program written in the memory of the control unit 4. When the calculation program is executed by the control unit 4, the center position calculation unit 41 functions as the center position calculation unit 41. To do.

  The calculation is based on the edge position storage step for reading the edge coordinates obtained by detecting the edge twice and the rotation angle of the first link corresponding to the edge coordinates from the control unit 4, and the circular transfer based on the information. A center position calculating step of calculating center position coordinates of the object W and storing the obtained center position coordinates in the control unit 4.

  First, the edge position storing step will be described.

  In FIG. 6, the first link 21 holding the regular circular conveyance object W is rotated clockwise about the rotation axis C1 (the regular circular conveyance object W passes from the left side to the right side toward the edge detection unit 3). Then, it is assumed that the detection position Se of the edge detection unit 3 is on the y axis.

FIG. 6A shows a case where the edge detection unit 3 is turned on (hereinafter referred to as “sensor on”) (when the edge detection unit 3 starts detecting the regular circular conveyance object W), which will be supplementarily described later. the rotation angle with respect to the second link 22 of the first link 21 at this time is theta _2.

FIG. 6B shows the case where the edge detection unit 3 is turned off (when the sensor has finished detecting the circular object to be transferred W), and (x ₂ , y ₂ ) is the circular detection that the edge detection unit 3 transfers. The coordinates of the movement destination of the edge when the object W starts to be detected, and (x ₁ , y ₁ ) are the coordinates of the edge when the edge detection unit 3 finishes detecting the regular circular conveyance object W. The rotation angle of the first link 21 with respect to the second link 22 at this time is θ ₁ .

  Although it is the above-mentioned supplementary explanation, as the said rotation angle with respect to the 2nd link 22 of the 1st link 21 is shown by FIG.4 (b), the 1st link 21 and the 2nd link 22 are as follows. This indicates the rotation angle when the first link 21 rotates the joint portion 24 clockwise when θ = 0 degrees is set in a straight line via the joint portions 24 of both links.

  However, since this angle is one setting example, the position is not limited to this, and the position where θ = 0 degree can be arbitrarily selected, and the counterclockwise direction can be set as the positive direction of the rotation angle.

Here, θ _{1 and} θ ₂ in FIG. 6 are signals E1 from the rotation angle detection unit 27 attached to the shaft motor 28 provided at the tip 22a of the second link 22 to the control unit 4 (see FIG. 1). Is output as

These pieces of information are stored in the control unit 4, and the center position calculation unit 41 detects the two edge coordinates (x ₁ , y ₁ ), (x ₂ , The rotation angle θ ₁ , θ ₂ of the first link corresponding to y ₂ ) with respect to the second link 22 is collected, and a program embodying the following algorithm for calculating the center position stored in advance is stored in the control unit 4. To run.

FIG. 5 shows the position of the regular circular conveyance object W when the edge of the regular circular conveyance object W has been detected for the second time in the xy coordinates. (X ₁ , y ₁ ) is The coordinates at the end of edge detection coincide with the detection position Se of the edge detection unit 3. (X ₂ , y ₂ ) are the coordinates of the movement destination of the point where the edge at that time has started to be detected, and (a, b) are the coordinates of the center position of the regular circular conveyance object W.

  Here, the origin O is the rotation axis C1 of the first link 21 shown in FIG. 1 and FIG. 2, and the distance from the origin O of the first link 21 to the detection position Se of the sensor is R, and a circular transfer is performed. Let r be the radius of the object W.

The rotation angle amount of the first link 21 to the second link 22 during sensor operation is θ = θ ₁ −θ _2.

θ ₁ : When the sensor is turned off (when the edge detection unit 3 has finished detecting the regular circular conveyance object W)

θ ₂ : When the sensor is on (when the edge detection unit 3 starts to detect the regular circular conveyance object W)
As shown in FIGS. 5 and 6B, when the edge detection unit 3 finishes detecting the circular conveyance object W (when the sensor is off), the detection position coordinates of the circular conveyance object W are ( When x ₁ , y ₁ ) = (0, R),
(X ₂ , y ₂ ) = (R sin θ, R cos θ)
It is represented by

となる。 Since the equation of the circle representing the regular circular conveyance object W is (x−a) ² + (y−b) ² = r ² ,

It becomes.

とすると、

となり、θ、Ｒ、ｒは既知の値であるから、センサが正円形搬送対象物Ｗを検出し終えた時（センサオフ時）の正円形搬送対象物Ｗの中心座標（ａ，ｂ）が中心位置算出部４１により算出される。 here,
(X ₁ , y ₁ ) = (0, R)
Substituting (x ₂ , y ₂ ) = (R sin θ, R cos θ)

Then,

Since θ, R, and r are known values, the center coordinates (a, b) of the regular circular conveyance object W when the sensor finishes detecting the regular circular conveyance object W (when the sensor is off) are centered. Calculated by the position calculation unit 41.

Since the center coordinates are coordinates when the rotation axis of the first link 21 is the origin O and the coordinates (x ₁ , y ₁ ) when the edge is detected is (0, R), the center position is calculated. Of the information obtained by detecting the edge twice, the unit 41 actually uses the coordinates (x ₁ , y ₁ ) when the edge of the regular circular conveyance object W has been detected as a reference, and The center position coordinate of the actual circular transfer object W is calculated.

  When the center position calculation unit 41 executes the program embodying the algorithm described above, the obtained center position coordinates are stored in the memory of the control unit 4 and the center position calculation step is completed.

  Then, the center position deviation determination unit 42 uses the center position calculation unit 41 to execute a program embodying the following algorithm for the position deviation from the center position where the regular circular conveyance object W should be originally located. Judging by.

  In order to detect displacement, first, a reference point is obtained. In the present embodiment, the center position of the regular circular conveyance object W when the regular circular conveyance object W is held by the first link 21 without any deviation from the reference point is the rotation axis of the first link 21. Located on the center line of the link 21 extending from O (C1) toward the tip of the link so as to be symmetrical (see, for example, the states of FIGS. 1, 4, 6, etc.) For example, it is set at a position where there is no hindrance to the transportation of the article W to, for example, FOUP (Front Opening Unified Pod).

  The reference center position as a reference point is obtained by calculation from the original installation conditions of the robot and the dimensions of each part of the robot, and the reference center position coordinates are set by teaching or the like.

  In addition to this method, the center position deviation determination unit 42 performs the center position calculation step for the regular circular conveyance object W placed on the first link 21 without any deviation. It is also possible to calculate the reference center position coordinates by causing the control unit 41 to execute it.

  The reference center position coordinates calculated in this way are stored in the memory of the control unit 4 in advance, and the center position calculation unit 41 is caused to execute the actual center position of the regular circular conveyance object W whose positional deviation is to be known.

Then, as shown in FIG. 7, the actual center position coordinates of the regular circular conveyance object W placed shifted on the first link 21 are (a ₁ , b ₁ ), and the reference center position coordinates are (a ₀ , b ₀ ), the center position deviation determination unit 42 determines (Δx, Δy) = (a ₁ −a ₀ , b ₁ −b ₀ ), which is the difference between the coordinates, as the center position deviation. ing.

  If the reference center position coordinates are stored in the memory of the control unit 4 together with the identification data of the regular circular conveyance object W, it is sufficient to calculate only the actual reference position only by inputting or selecting the identification data. It becomes.

  As described above, the arm-type transfer apparatus according to the present embodiment is the first base member that can turn the first link 21 holding the circular transfer object W in the horizontal plane via the rotation axis C1. The edge of the right circular conveyance object W is positioned at the detection position Se that is attached to the second link 22 together with the rotary shaft C1 and is determined according to the attachment position. An edge detection unit 3 to detect, a rotation angle detection unit 27 to detect the rotation angle θ of the first link 21 with respect to the second link 22, and the edge of the regular circular conveyance object W pass through the edge detection unit 3 A center position calculation unit 41 that calculates the center position of the circularly circular object W relative to the link 21 based on the corresponding rotation angle θ detected by the rotation angle detection unit 27. Since it comprised, the aligner installed separately from the arm type | mold conveying apparatus only by allowing the 1st link 21 holding the perfect circular conveyance target object W to pass through the edge detection part 3 of the 2nd link 22 which is a base member. For example, the center position coordinates of the regular circular conveyance target W can be calculated from the rotation angle detection unit 27 and the center position calculation unit 41 without the need to align the regular circular conveyance target W one by one. In addition, the alignment time can be greatly shortened, and the cost can be greatly reduced.

Further, a center position deviation determination unit 42 for detecting a position deviation of the regular circular conveyance object W based on the center position calculated by the center position calculation unit 41 is provided, and the center position deviation determination unit 42 is given in advance. When the center position calculation unit 41 calculates the reference center position {coordinates (a ₀ , b ₀ )} and the circular object to be measured W placed on the first link 21 to be measured. The center position deviation from the reference center position to the actual center position is determined based on the actual center position {coordinates (a ₁ , b ₁ )} of the For those that can determine the misalignment of the center position of the regular circular conveyance object W and do not need to correct the rotation axis in the aligner, the misregistration of the regular circular conveyance object W with respect to the link 21 is controlled. Command from 4 Accordingly, since the circular transfer object W can be transferred to the transfer object transfer destination such as FOUP while correcting with the link 21, the time for transfer and alignment can be greatly shortened, and the cost can be greatly reduced. It becomes possible.

  For aligners that need to be corrected in the direction of the rotation axis, all the X-axis, Y-axis, and rotation-axis directions can be adjusted because they can be transported to the aligner to detect only the displacement in one direction. It is possible to shorten the operation time as compared with the case of aligning with the aligner.

  Further, after the reference center position coordinates once adopted are stored in the memory of the control unit 4 together with the identification data, a different type of conveyance object is conveyed thereafter, and the same circular conveyance object W as described above is again formed. In the case of carrying, it is only necessary to read the reference center position coordinates stored in the memory into the control unit 4 without detecting the edge again and calculating the center position coordinates. It becomes possible to grant.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in this embodiment, the edge detection unit 3 is attached to the second link 22, but is not limited to this as long as it is a link closer to the base end than the first link 21. You may attach to the link 23. In the present embodiment, the arm mechanism is configured by connecting the three links 21 to 23 so as to be rotatable in a horizontal plane, but may be configured by connecting two or four or more links.

  Furthermore, in this embodiment, a transmissive photoelectric sensor is used as the sensor, but a reflective photoelectric sensor may be used. If it is a reflective photoelectric sensor, it can be embedded in the arm, not the arm end.

  Furthermore, the trajectory correction described above is applied to a transport device provided with an arm mechanism configured by connecting a plurality of links in series in a rotatable manner. However, the trajectory correction is applied to a transport device using other arm mechanisms. Is also applicable. For example, a transport device such as a parallel manipulator in which a plurality of links are connected in parallel can be used.

  In addition, in this embodiment, it is configured to hold a circular transfer object such as a wafer by placing it on a first link (end effector). You may comprise so that it may hold | maintain with a chuck | zipper etc.

  In addition to the above, the specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

2 ... Arm mechanism 3 ... Edge detector 21 ... First link 22 ... Second link (base member)
27 ... Rotation angle detector (encoder)
41 ... Center position calculation unit 42 ... Center position deviation determination unit C1 ... Rotation axis Se ... Detection position W ... Regular circular transfer object (wafer)

Claims (2)

An arm mechanism that is attached to the base member so that a link that holds a circular object can be rotated in a horizontal plane via a rotation shaft;
An edge detection unit that is attached to the base member together with the rotation shaft and detects that an edge of a regular circular conveyance object is located at a detection position determined according to the attachment position;
Based on the rotation angle detection unit that detects the rotation angle of the link relative to the base member and the corresponding rotation angle detected by the rotation angle detection unit when the edge of the regular circular conveyance object passes through the edge detection unit. An arm-type transfer apparatus comprising: a center position calculation unit that calculates a center position of a circular object to be conveyed with respect to a link.   A center position deviation determination unit for detecting a position deviation of a regular circular conveyance object based on the center position calculated by the center position calculation unit is provided, and the center position deviation determination unit is given in advance. Based on the reference center position and the actual center position when the center position calculation unit calculates the regular circular conveyance object to be measured placed on the link from the reference center position to the actual center position. The arm type transfer device according to claim 1, wherein the center position deviation is determined.

Images