Patent ID: 8628288

Claim:
A substrate transport apparatus comprising: a drive mechanism; a movable arm assembly connected to the drive mechanism; an end effector connected to the movable arm assembly; a chuck for holding a substrate, the chuck being mounted on the end effector and having a movable edge gripper with a contact surface, the movable edge gripper has an open and closed position wherein an edge of the substrate is gripped by actuating the movable edge gripper from the open position, wherein the contact surface is disengaged from the substrate and the substrate is unclamped, to the closed position that causes the contact surface to come into contact with the substrate so that the contact surface engages the substrate and the substrate is clamped by the movable edge gripper; and a motion sensor configured to sense acceleration of the end effector and to provide a close signal when the substrate is placed on the chuck and is unclamped or to provide an open signal when the substrate is on the chuck and is clamped, to actuate the movable edge gripper to move from the open position to the closed position and from the closed position to the open position for respectively clamping and unclamping the substrate; wherein the movable edge gripper is configured so that in response to the close signal from the motion sensor sensing acceleration of the end effector the movable edge gripper is actuated from the open position, in which the substrate positioned on the chuck is disengaged from the contact surface and is unclamped, to the closed position wherein the substrate becomes engaged and clamped by the edge gripper, and in response to an open signal from the motion sensor sensing acceleration of the end effector the movable edge gripper is actuated from the closed position to the open position producing disengagement from and unclamping of the substrate.