RAJENDER MALHOTRA
Broker in Beverly Farms, MA
License number
Massachusetts 78744
Issued Date
Mar 1, 1986
Expiration Date
Jul 16, 1988
Type
Salesperson
Address
Address
Beverly Farms, MA 01915
Professional information
Missing Or Broken Wafer Sensor
US Patent:
4513430, Apr 23, 1985
Filed:
May 24, 1982
Appl. No.:
6/381290
Inventors:
Mahasukh Vora - Beverly MA
Rajender Malhotra - Beverly MA
Rajender Malhotra - Beverly MA
Assignee:
Varian Associates, Inc. - Palo Alto CA
International Classification:
G01B 1104, G04F 1004
US Classification:
377 39
Abstract:
Apparatus for sensing a missing or broken wafer in an automated wafer transfer system. The apparatus includes means for moving a wafer transfer mechanism from a first position along a prescribed path. A counter coupled to an oscillator is enabled when the wafer transfer mechanism and a wafer are moved away from the first position. A photosensor senses the presence of the wafer at a second position along the prescribed path and inhibits the counter. The count stored in the counter is compared with a predetermined count corresponding to the time required for movement of an unbroken wafer to the second position. If the counts do not agree, a missing or broken wafer is indicated and corrective action is taken.