Method and apparatus for compensating positioning error in magnetic-head and magnetic-disk tester

摘要

A magnetic head and disk tester which has linear encoders (40 and 42) installed on lateral sides of a carriage (30) which carries a magnetic head (34), movable in a radial direction along a hard disk. Positions of the magnetic head with respect to the hard disk are measured by means of the linear encoders which are arranged on both lateral sides of the carriage. Outputs of the encoders are supplied to an arithmetic unit (45) which calculates the arithmetic mean of the encoder's outputs and transmits the resulting signal via a feedback line (47) to a piezoelectric translator (37). The translator is the final drive element in the carriage-drive system and is used for fine positioning of the carriage. Thus, if during positioning of the magnetic head the latter is installed in an erroneous position, e.g., because of yawing which may result from asymmetrical friction on both sides of the carriage, the feedback-positioning system composed of the encoders, the arithmetic unit, and the piezoelectric translator calculates the error and shifts the carriage in a direction opposite to the error to the correct position.