Patent ID: 8683643

Claim:
A stocker comprising: a main body unit having a plurality of receiving shelves; a transfer unit transferring a received material to be moved to the main body unit; a robot arm stacking the received material transferred by the transfer unit on one of the receiving shelves of the main body unit; a dirt collecting unit moving in conjunction with the robot arm to remove particles from inside the main body unit from a first receiving shelve of the plurality of receiving shelves, said dirt collecting unit having a dirt collecting duct contained entirely within the robot arm or entirely attached directly to the robot arm that moves in conjunction with the robot arm; and a cleaning pad having a base substrate and an absorbing unit formed at an underside edge of the base substrate, said cleaning pad is stacked on the main body unit so that the absorbing unit contacts an upper side surface of a second shelve of the plurality receiving shelves of the main body unit, wherein dirt is simultaneously removed from the first and second shelves, said first and second shelves are different and separate shelves.