Excel Precision Corporation

Jean Chi

John C Tsai

Hubert Song

Kam-Fung Yan

Mervyn L Hopson

A servotrack writing apparatus (10) for use on computer disk drive workpieces (12). A writer controller (58) puts the writing apparatus (10) in the role of master to direct the workpiece (12) as a slave to position its read-write head (36) and to write the servotracks. A tracking section (54) provides a modulated light beam (72) from which a reflected portion is detected by a bi-cell photo sensor (70) and processed in the writer controller (58) to determine the position of a thru-hole (40) or a detection region (42) in the actuator arm (24) of the workpiece (12). The writer controller (58) may use a lock-in amplifier (102, 104) for the processing the reflected portion of the light beam (72). A reference arm (44) is locked and moved in a synchronous relationship with the actuator arm (24). A measurement section (56) determines the position of the reference arm (44), and may include an interferometer system (122) having a differential head (128) and a differential target (124), to permit increased resolution and nulling of errors. The interferometer system (122) may also use multiple frequency techniques to further increase resolution.

Growing community of inventors

San Jose, CA, United States of America

Jean Chi