Altra, Inc.

Raymond B Larsen

Mark A Edwards

Robin W Chu

A disk drive head position encoder is for use in a disk drive having a storage media, a read/write head and an actuator configured to control a position of the head. The position encoder includes a scale having gratings formed by undulations configured to distort light penetrating therethrough. A light source is configured to penetrate the scale and to direct light onto a photodetector, where the photodetector is configured to generate a photodetector signal in response to the light. A processor is coupled to the photodetector and the actuator and configured to determine a head position of the head on the storage media by processing the photodetector signal. In one embodiment, the is constructed from a material having a coefficient of thermal expansion similar to that of said storage media. In another embodiment, the processor includes an analog to digital convertor configured to convert the photodetector signal to a digital signal representative of an amplitude of the photodetector signal, and the processor is configured to determine the head position based at least in part on the digital signal. Advantages of the invention include the ability to accurately position the head on the storage media tracks during prolonged operation of the disk drive. As a result, the recording tracks on the storage media can be made very small and the head can be accurately placed on the recording tracks.

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Rawlins, WY, United States of America

Raymond B Larsen