Patent ID: 6122132
Filing Date: 2000-09-19
Classification: G11B

Abstract:
A disk drive head position encoder for use in a disk drive having a storage media, a head coupled to an arm having a fixed pivot point and an actuator configured to control a position of said head, comprising:a scale coupled to said arm having gratings formed by undulations configured to distort light penetrating therethrough;a light source configured to penetrate said scale and to direct light onto a photodetector, said photodetector configured to generate a photodetector signal in response to said light; anda processor coupled to said photodetector and said actuator and configured to determine a head position of said head on said storage media by processing said photodetector signal;wherein said scale is constructed from a material having a coefficient of expansion similar to that of said storage media; andwherein said processor is configured to compensate for the movement of said head position by an amount equal to the ratio of an effective distance L1 of the scale from the pivot point to an effective distance L2 of the head from the pivot point.