Rotating shuttle payload platform

Details Rotating shuttle payload platform Rotating shuttle payload platform

1999-11-10

2001-08-14

Valenza, Joseph E. (Department: 3651)

Conveyors: power-driven

Conveyor for changing attitude of item relative to conveyed...

By actuating item-holder relative to holder-carrying conveyor

C198S377010

Reexamination Certificate

active

06273237

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The present invention relates generally to manufacturing operations, and more specifically to a system and apparatus for transport of semiconductor wafers in a semiconductor wafer fabrication facility.
Shuttle platforms are known which transport a payload, such as a semiconductor wafer pod, about a manufacturing facility. The payload is manipulated by various fabrication processes at different locations. The use of a shuttle platform expedites transport, provides precise placement, and minimizes the potential for operator error, such as a dropped payload. In manufacturing of delicate products, such as semiconductor wafers, operator error can result in substantial losses.
It is often advantageous to rotate a payload on a shuttle platform. Rotation serves to dispose the payload for optimal access by the various fabrication processes which manipulate the payload. A payload may be rotated to orient the payload for storage, to position the payload for access to a sealed environment, to allow for pickup by a robotic arm, and for other fabrication operations.
Rotation may be provided by direct activation from a drive source, such as a servo motor, or selectively provided through a rotary indexing mechanism. A separate drive source, however, must then be provided and powered, thereby increasing complexity and cost. Further, such a drive source must be calibrated to provide the precise positioning required. Finally, as a payload such as semiconductor wafers must not be subjected to bumping or jarring, rotation must not accelerate or decelerate too abruptly to avoid damaging the payload.
It would be beneficial, therefore, to provide a rotating payload platform which does not require a separate drive source, which provides a smooth motion profile through rotary acceleration and deceleration, and which minimizes calibration maintenance without sacrificing precision of rotation.
BRIEF SUMMARY OF THE INVENTION
A semiconductor wafer pod payload platform is operable for rotation in response to linear movement of the platform by a cam assembly having rollers adapted to engage a cam surface. The payload platform is rotatably attached to a shuttle platform adapted for movement along linear rails. The shuttle platform is supported by shuttle glides adapted to move along the linear rails. A cam follower assembly is connected to the payload platform through a shaft extending through the shuttle platform and operable to rotate the payload platform. A cam surface substantially parallel to the linear rails is adapted to engage rollers on the cam follower assembly. Linear movement of the shuttle platform causes the rollers on the cam follower assembly to engage the cam surface and dispose the cam follower assembly so as to rotate the payload platform via the shaft.
A shuttle drive motor attached to the shuttle platform drives the platform along the linear rails by engaging a gear or roller along a drive track surface. As the shuttle platform moves, the rollers on the cam follower assembly follow the contour of the cam surface. The cam follower assembly has a plurality of rollers which follow different cam tracks on the cam surface. The cam follower assembly is therefore rotated as the rollers are disposed along the cam surface. The payload platform is thus rotated by the cam follower assembly through the shaft. Since rotary motion is derived from the linear movement through the cam assembly, no additional rotational drive sources are required. The cam surfaces do not require adjustment, and are shaped so as to provide a smooth cycloidal rotational momentum from a constant linear velocity.


REFERENCES:
patent: 3283883 (1966-11-01), Cruzen, Jr.
patent: 3952874 (1976-04-01), Owen
patent: 4886155 (1989-12-01), Toyonaga et al.
patent: 5014843 (1991-05-01), Linton et al.
patent: 5535999 (1996-07-01), Ford
patent: 5579890 (1996-12-01), Harris

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