Material or article handling – Horizontally swinging load support – Swinging about pivot
Reexamination Certificate
1998-10-16
2002-12-10
Underwood, Donald W. (Department: 3652)
Material or article handling
Horizontally swinging load support
Swinging about pivot
C414S936000
Reexamination Certificate
active
06491491
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to an articulated robot. Furthermore, the present invention relates to an articulated robot which transfers a workpiece, such as a semiconductor wafer.
b) Description of the Related Art
An articulated robot is used for transferring a workpiece such as a semiconductor wafer from a cassette to a processing device for photo lithography, deposition and etching. For example, as shown in FIG.
16
(A), articulated robot
100
comprises base
101
, first arm
102
, which is rotatably supported by base
101
, second arm
103
, which is rotatably supported by first arm
102
, and hand portion
104
which is supported by the end of second arm
103
. Articulated robot
100
transfers workpiece
107
from cassette
105
to processing device
106
.
In the case where a semiconductor wafer is used as workpiece
107
, it is necessary to maintain the direction of workpiece
107
for a thermal processing and deposition since the crystals of each semiconductor wafer have a directional property. Therefore, it is required to keep all workpieces
107
, . . . ,
107
on processing device
106
in the same direction when they are transferred.
For the above reasons, a mark, such as a notch and a D flat, is formed at a given position on the edge of workpiece
107
while a workpiece rotating device, called aligner
108
, having a means to detect the mark is formed, separate from cassette
105
and processing device
106
as shown in FIG.
16
. As shown in FIGS. (A) through (C), workpiece
107
, which is removed from cassette
105
by hand portion
104
, is first mounted on aligner
108
(FIG.(D)); after the direction of the workpiece is aligned in a given direction by turning it, workpiece
107
is transferred to and mounted on processing device
106
in a given direction (FIGS. (E) and (F)).
However, as shown in
FIG. 17
, if base
101
is formed such that workpiece
107
can be transferred by sliding to each of processing devices
106
, . . . ,
106
, which are connected in parallel, the time required to transfer workpiece
107
becomes longer. In other words, it is necessary for workpieces
107
, . . . ,
107
to pass through aligner
108
to align the workpieces in one direction, and there is usually only one aligner
108
for two cassettes
105
,
105
and a plurality of processing devices
106
, . . . ,
106
. Therefore, if one wants to transfer workpiece
107
from lower cassette
105
to processing device
106
at the bottom in the figure, workpiece
107
must pass through aligner
108
; as a result, distance of transfer by robot
100
becomes longer such that it takes a longer time for workpiece
107
to be transferred.
Also, if one wants to transfer workpiece
107
from upper cassette
105
to processing device
106
at the top in the figure, workpiece
107
cannot be transferred until the orientation for alignment by aligner
108
is complete; therefore, robot
100
shall be idling while the orientation is carried out.
On the other hand, articulated robot
100
, which transfers a workpiece such as a semiconductor wafer from a cassette to a processing device and vice versa, generally comprises two arms
102
,
103
and hand portion
104
, as shown in
FIG. 18
, such that workpiece
107
can be transferred along a linear path. In the case of such an articulated robot
100
, or articulated robot
100
having three arms
102
,
103
,
113
as shown in
FIG. 19
, hand portion
104
holding workpiece
107
is linearly transferred in the axial direction of the hand portion such that workpiece
107
can be transferred without being rotated.
There are known transportation mechanisms such as a belt and pulley, in which two arms
102
,
103
can be formed to be mechanically connected, as a means to linearly move hand portion
104
. Due to these mechanisms, articulated robot
100
limits movements of arms
102
,
103
(,
113
). Additionally, each of workpieces
107
mounted at various positions in a connected plurality of cassettes can be transferred from each position by being held by hand portion
104
.
However, when hand portion
104
is transferred while the axis of hand portion
104
passes through the vicinity of the rotational center of arm
102
, that is, when the center of transferred workpiece
107
shows a path passing the vicinity of rotational center
116
, a rapid rotation of arm
102
is required at rotational center
116
of arm
102
, and such a position is called a singularity. As a result, an excessive load may be caused in the movement of arms
102
,
103
of the above mechanism. In other words, as shown in FIGS.
20
(A) through (C), when support point
117
of hand portion
104
passes the vicinity of rotational center (singularity)
116
of arm
102
, each of arms
102
,
103
are required to move around rotational center (singularity)
116
for about 180 degree. Additionally, if workpiece
107
is transferred at a constant speed, each of arms
102
,
103
must be rapidly and vigorously rotated such that unnatural movement will be caused therein. This phenomena is also observed in articulated robot
100
having three arms
102
,
103
,
113
and hand portion
104
as shown in FIG.
21
.
On the other hand, as shown in
FIG. 22
, articulated robot
100
having direct-acting mechanism
119
capable of a horizontal transfer together with base
121
has been suggested. According to this mechanism, horizontal transfer of workpiece
107
is possible while hand portion
104
is distant from rotational center
116
of arm
102
. Consequently, hand portion
104
does not have to pass the vicinity of rotational center
116
of arm
102
; thus, the above problems related to the generation of a singularity can be solved. Nonetheless, to form articulated robot
100
such that it is capable of a linear movement including base
121
, a space for direct-acting mechanism
119
is needed. In addition to dust generated by direct-acting mechanism
119
during transfer, it is difficult to seal the dust inside the robot such that the robot is not able to be used in a clean room.
OBJECT AND SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to improve the above problems which an articulated robot to transfer a workpiece, such as a semiconductor wafer, conventionally has had. More specifically, the present invention intends to provide an articulated robot in which workpieces can be transferred while orientation of the workpieces is carried out such that efficiency of transfer of workpieces is improved. Another object is to provide an articulated robot in which transfer of workpieces can be carried out without unnatural movement in arms and generation of dust is minimized during transfer of workpieces.
In accordance with the invention, an articulated robot comprises a movable first transferring portion and a second transferring portion movably supported in relation to the movable first transferring portion by a joint portion. A workpiece is positioned at a position, where a workpiece positional deviation detecting means is located, by a hand portion formed at an end of the second transferring portion. The workpiece positional deviation detecting means detects the amount of deviation in the position of the workpiece. A positioning portion of the workpiece and a sensor portion for detecting deviations of the workpiece are formed either at the first transferring portion or the second transferring portion which form the articulated robot. A detecting operation by the sensor portion and transferring of the first and second transferring portions are enabled when the workpiece is positioned at the positioning portion of the articulated robot.
REFERENCES:
patent: 4675516 (1987-06-01), Guion
patent: 4693663 (1987-09-01), Brenholt et al.
patent: 5306380 (1994-04-01), Hiroki
patent: 5746565 (1998-05-01), Tepolt
patent: 5944476 (1999-08-01), Racchi et al.
patent: 0556865 (1993-08-01), None
patent: 0617488 (1994-09-01), None
patent: 0774732 (1997-05-01), None
patent: 0913236 (1999-05-01), None
patent: 2774
Kitahara Yasuyuki
Tsuneda Haruhiro
Reed Smith LLP
Sankyo Seiki Mfg. Co. Ltd.
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