Material or article handling – Horizontally swinging load support – Swinging about pivot
Reexamination Certificate
2001-11-13
2004-07-20
Underwood, Donald W. (Department: 3652)
Material or article handling
Horizontally swinging load support
Swinging about pivot
C901S015000, C901S021000, C074S490050
Reexamination Certificate
active
06764271
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a robot for conveying a substrate, for example, a substrate conveyer robot suitable for use in conveying a semiconductor wafer substrate to place it in a container such as a cassette, and to take it out from the container.
2. Related Art
Conventionally, a wafer substrate conveyer robot of the belt link type has an arm expansion/contraction mechanism with first through third arms, in which the gear ratio of the pulley furnished on the rotation spindle of each arm is 2:1:2. This type of robot conveys the substrate horizontally by the control of only two axes. One of them is a robot advancing/retreating axis R for linearly advancing and retreating the third arm by the belt link mechanism, and the other one is a robot revolving axis &thgr; for revolving the rotary base of the robot. Further, with lifting/lowering of all arms, the robot inserts and removes the substrate to and from the cassette.
In general, a substrate conveyer robot
01
possesses an arm expansion/contraction mechanism composed of three arms
05
,
07
,
09
, and the two control axes, i.e., the robot revolving axis &thgr; and the robot advancing/retreating axis R. As illustrated in
FIG. 11
, the center of the substrate
030
held by a hand
010
fixed on the third arm
09
advances and retreats along a straight line J
0
that passes through the center of a rotary shaft (=a first spindle; this is positioned on the same axis as the robot revolving axis &thgr;) of the first arm
05
. Thus, the substrate conveyer robot
01
is designed to convey and insert the substrate
030
only into a cassette
032
that is disposed with its face centered on the line J
0
. Here, the straight line J
0
coincides with the robot advancing/retreating axis R.
The cassette
032
is in the shape of a quadrangle, and permits the substrate
030
to be inserted only from one direction perpendicular to the plane of the opening thereof. In the case of the conventional robot with two axes, as illustrated in FIG.
11
(
a
) through FIG.
11
(
c
)), the robot
010
or cassette
032
has been required to be disposed in such a manner that the center line of the cassette
032
perpendicular to the aperture plane passes through the robot revolving axis &thgr; (the pivotal center). A rotation base
03
is rotatable around the robot revolving axis &thgr;, so that the third arm
09
can be positioned perpendicular to the front of the cassette
032
. The third arm
09
is advanced and retreated linearly along the robot advancing/retreating axis R (the straight line J
0
), thereby inserting and taking out the substrate
030
to and from the cassette
032
. In other words, the control of the rotating movement around the robot revolving axis &thgr; and the control of the advancing and retracting movement along the robot advancing/retreating axis R have been carried out sequentially, not simultaneously.
As described above, most of the conventional robots possessing two control axes, the robot revolving axis &thgr; and the robot advancing/retreating axis R, presumably, do not combine the control of rotation around the robot revolving axis &thgr; with simultaneous control of the advancing and retracting along the robot advancing/retreating axis R. Therefore, the conventional robots could only insert and remove the substrate to and from the cassette that is positioned in a radial manner to (in other words, positioned right in front of) the robot revolving axis &thgr;.
Therefore, in order for the robot to control the insertion and removal of the substrate to and from the cassette, even in case the cassette is positioned on an arbitrary straight line deviating from the robot revolving axis &thgr;, there was no way to use such a robot other than that disclosed in Japanese Patent Laid-Open No. Hei 11(1999)-33948 Publication. This robot adds one axis to the foregoing two axes (two control axes) to freely control the position and direction of the hand of the last arm in the horizontal plane.
However, the use of the robot disclosed in the above publication requires an extra drive along the additional axis, and at the same time complicates control, thus increasing the cost.
The substrate conveyer robot illustrated in
FIG. 11
is a single arm sequence type, having an arm expansion/contraction mechanism composed of three arms operative in a single sequence. However, a double arm sequence type substrate conveyer robot that has (a pair) bilaterally symmetrical arm expansion/contraction mechanisms operative in two sequences has the same problem as described above.
SUMMARY OF INVENTION
The present invention has been made with a view toward solving the above-described problems of the conventional substrate conveyer robots, and an object of the invention is to provide a substrate conveyer robot that can insert and remove a substrate to and from a container disposed in an arbitrary position and orientation, within an accessible range of the robot hand, with a minimum number of control axes, and at a low production cost.
To accomplish the foregoing object, according to one aspect of the invention, the substrate conveyer robot is provided with a rotatable base
3
rotatably driven by a first motor M
1
inside the body of the robot, which has a rotational axis Q, on which a first spindle
4
is located in a state isolated from the rotation of the rotatable base
3
, which is coaxial with the rotational axis Q, and is rotatably driven by a second motor M
2
. One end of a first arm
5
is attached to the first spindle
4
and a second spindle
6
protrudes from the other end of the first arm
5
independent of the rotation of the first arm
5
, which is rotated with a gear ratio of 2:1 by way of pulleys and a timing belt inside the first arm
5
. One end of a second arm
7
is attached to the second spindle
6
and a third spindle
8
protrudes from the other end of the second arm
7
and is independent of rotation of the second arm
7
, which is rotated at a gear ratio of 1:2 by way of pulleys and a timing belt inside the second arm
7
. The distance between the first spindle
4
and the second spindle
6
is equal to the distance between the second spindle
6
and the third spindle
8
. One end of a third arm
9
is attached to the third spindle
8
and a hand
10
for holding a substrate is firmly attached on the other end of the third arm
9
. With the angle of rotation of the rotation base
3
represented by &thgr; and the angle of rotation of the first arm
5
is represented by &phgr;, a control device is provided which controls the angles of rotation &thgr; and &phgr; in such a manner that the center point of the substrate held by the hand
10
, horizontally spaced from the pivotal center Q, moves linearly relative to the body of the robot on the straight line H, in an arbitrary direction within an accessible range of the hand
10
, and the substrate is inserted into and removed from a container, while the substrate is being rotated.
The substrate conveyer robot with the above construction is a so-called single arm sequence type substrate conveyer robot having a single sequence arm expansion/contraction mechanism that contains the first through third arms
5
,
7
, and
9
. The control device controls the angle of rotation &thgr; of the rotatable base
3
provided in the body of the robot and the angle of rotation &phgr; of the first arm
5
, in such a manner that the center point of the substrate held by the hand
10
, spaced from the pivotal center Q, moves linearly relative to the body of the robot on the straight line H in an arbitrary direction within the accessible range of the hand
10
, and the substrate is inserted into and removed from the container, while the substrate is being rotated. Therefore, in contrast to the conventional single arm sequence type substrate conveyer robot, the invention provides a substrate conveyer robot that can insert and remove the substrate to and from the container disposed in an arbitrary position and direction within the accessible range of
Hirata Corporation
Lorusso, Loud & Kelly
Underwood Donald W.
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