Methods and apparatus for positioning a substrate relative to a support stage

1. A substrate positioning system adapted to adjust a position of an edge of a substrate relative to a stage that supports the substrate, comprising:

a plurality of pushing devices and stops arranged in a spaced relation around a stage that is adapted to support a substrate, wherein each stop occupies a fixed position relative to the stage and each pushing device comprises a movable pusher that is adapted to:

extend toward an edge of the substrate that is supported by the stage;

contact the edge of the substrate while the substrate is supported by the stage; and

continue extending so as to cause the substrate to translate relative to the stage toward one or more of the stops until the substrate contacts the one or more stops;

wherein each pushing device further comprises a biasing device coupled to the pusher of the pushing device and adapted to move the pusher toward the edge of the substrate; and

wherein each pushing device further comprises a retracting device coupled to the pusher of the pushing device and adapted to counteract the biasing device so as to move the pusher away from the edge of the substrate.

2. The substrate positioning system of claim 1 , wherein each pushing device is adapted to:

cause the pusher of the pushing device to extend toward the edge of the substrate that is supported by the stage;

cause the pusher of the pushing device to contact the edge of the substrate while the substrate is supported by the stage; and

cause the pusher of the pushing device to continue extending so as to cause the substrate to translate relative to the stage toward one or more of the stops until the substrate contacts the one or more stops.

3. The substrate positioning system of claim 2 wherein:

the pusher of each pushing device is further adapted to retract from the edge of the substrate; and

each pushing device is further adapted to cause the pusher of the pushing device to retract from the edge of the substrate.

4. The substrate positioning system of claim 1 further comprising a controller coupled to each pushing device, and adapted to:

cause the pusher of each pushing device to extend toward the edge of the substrate that is supported by the stage;

cause the pusher of each pushing device to contact the edge of the substrate while the substrate is supported by the stage; and

cause the pusher of each pushing device to continue extending so as to cause the substrate to translate relative to the stage toward one or more of the stops until the substrate contacts the one or more stops.

5. The substrate positioning system of claim 1 , wherein each pusher is further adapted to extend toward the edge of the substrate along a straight-line path.

6. The substrate positioning system of claim 5 , wherein the plurality of pushing devices reside in a common plane containing the straight-line paths of the pushers.

7. The substrate positioning system of claim 6 , wherein the plurality of pushing devices include a first pushing device oriented such that the pusher of the first pushing device extends in a first direction, and a second pushing device oriented such that the pusher of the second pushing device extends in a second direction substantially perpendicular to the first direction.

8. The substrate postioning system of claim 1 , wherein the biasing device comprises a spring.

9. The substrate positioning system of claim 1 , wherein the retracting device comprises a bellows.

10. The substrate positioning system of claim 1 , wherein the biasing device and the retracting device are coupled to a common frame.

11. The substrate positioning system of claim 1 , wherein the stage is adapted to support glass substrates for flat panel displays.