Importance

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Abstract

A piezoelectric gripping system firmly secures a semiconductor wafer or other workpiece onto a robotic transfer blade so as to allow for acceleration forces that exceed the frictional holding force between the blade and workpiece. To prevent production of contaminating particulates during grasping, the piezoelectric grippers of the system are independently actuated into slight contact with the workpiece so as to prevent frictional movement of the workpiece relative to the blade during the grasping operation. Once all of the grippers are in slight contact with the workpiece, the voltage to each gripper is increased by a predetermined amount to thereby uniformly increase the force exerted by each gripper on the workpiece and to thereby more firmly secure the workpiece to the blade. Thereafter, the blade may transfer the workpiece at extremely high speeds without the workpiece moving frictionally relative to the blade.

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First Claim