Material or article handling – Horizontally swinging load support – Swinging about pivot
Reexamination Certificate
1999-03-23
2001-08-21
Underwood, Donald W. (Department: 3652)
Material or article handling
Horizontally swinging load support
Swinging about pivot
C414S917000, C901S019000
Reexamination Certificate
active
06276892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wafer handling apparatus and in particular relates to a wafer feeder adapted for wafer feed in a vacuum enclosure.
2. Description of the Related Art
Conventionally, in order to perform a wafer exchange operation, as shown in FIG.
9
and
FIG. 10
, equipment is known in which a blade
74
carrying a wafer is mounted at the tip of an arm
71
comprising a pair of freely bendable bending links
72
,
73
which are symmetrically arranged, the base ends of bending links
72
,
73
being supported so that they are rotatable in the peripheral direction, and the base ends of these bending links
72
,
73
being respectively driven in rotation by drive motors
77
,
78
and magnetic couplings
75
,
76
arranged on two vertical levels. Since bending links
72
,
73
have respectively independent drive axes, the equipment is constituted so as to sense their operations individually. Also, in the case of equipment where a plurality of arms
71
are arranged vertically, a complicated construction is provided below the arms to synchronize vertical drive of the arms in order to cut the number of drive axes.
Also, in the case of a single-direction double arm constituted such that a plurality of arms perform extension/retraction operation individually and towards a station in one direction, the blades of the upper and lower arm overlap during arm contraction, so, since it is not possible to use a transmission type sensor to identify on which blade the wafer is mounted, a reflective type sensor is arranged close to the blades.
However, the above prior art construction was subject to the problems that complicated control was required and the cycle time was made long since the operations of each drive shaft were sensed individually. Also, there was the problem that the swiveling radius became large due to the provision of a complex synchronization mechanism below the arm, and, with increasing wafer size, there was the problem that the mechanism itself tended to become of large size due to the need to strengthen the arm links, and a heavy object had thus to be raised and lowered.
Also, if a reflective type sensor was arranged close to the blade, there was the risk of interference with the wafer, blade or arm, etc. There was also a problem of unstable sensing occasionally caused by color differences on the surface of the wafer. To deal with these problems, a transmission type sensor could be arranged at some point along the path of extension/retraction of the arm and at each station, so as to detect which arm was extended and whether a wafer was placed thereon, but, if this was done, when the arm was driven, there was a risk of spurious detection due to the arm or blade passing over the transmission type sensor. This meant that the arm had to be stopped midway, or a time restriction monitored by a timer had to be imposed, leading to the problems of complicating the control operation and lowering the reliability of wafer sensing.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a wafer handling apparatus wherein the swiveling radius can be made small, drive of a single-direction double arm being achieved by a straightforward and compact mechanism, wherein the raising/lowering mechanism section can be reduced in weight, wherein high-speed feed can be achieved with a straightforward synchronization control, and wherein detection of the presence of a wafer can be performed with high reliability using a transmission-type sensor.
A wafer handling apparatus according to the present invention comprises: an upper double arm and a lower double arm, both being of a parallel link system, that are arranged within a vacuum enclosure and perform extension and retraction action in the same direction without mutual interference; a plurality of magnetic couplings arranged on an identical axis, through which drive of the respective extension/retraction action and swivel action of said upper and lower double arms are effected, whereby wafers can be delivered to a plurality of stations having a center point that coincides with said axis of the magnetic couplings in the vacuum enclosure; thus drive of a single-direction double arm can be effected with an uncomplicated and compact mechanism and the swiveling radius can be made small.
Also, by arranging upper and lower arm raising/lowering drive means below the magnetic couplings, the weight of the raising/lowering mechanism portion can be made small and generation of dust can be suppressed.
Also, by providing a cam box that drives three output shafts by a single input shaft, extension/retraction drive and raising/lowering drive of the upper and lower arms being performed by output shafts of the cam box, the wafer exchange operation being performed by a single arm drive motor and a swivel motor, high-speed feed can be achieved with uncomplicated synchronization control.
Also by providing detectors that identify whether a wafer is mounted on either of the upper and lower arms, arms using the parallel link system being employed, the presence of a wafer can be detected with high reliability using a transmission type sensor.
Also if detectors are arranged respectively in the directions of the vertices of a polygon in a polygonal vacuum enclosure wherein stations are arranged at each side, detectors can be shared by adjacent stations, making it possible to achieve high-reliability detection with a minimum number of detectors.
Also, if the speed of extension/retraction and the speed of swiveling of the upper and lower arms is altered in response to whether or not a wafer is carried, generation of dust can be reduced.
These and other objects, features and advantages of the invention will become more apparent upon a reading of the following detailed description and drawings.
REFERENCES:
patent: 5064340 (1991-11-01), Genov et al.
patent: 5604443 (1997-02-01), Kitamura
patent: 5720590 (1998-02-01), Hofmeister
patent: 5950495 (1999-09-01), Ogawa et al.
Haraguchi Hideo
Matsuda Izuru
Matsushita Electric - Industrial Co., Ltd.
Price and Gess
Underwood Donald W.
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