A system for cyclically generating a control signal for controlling the operation of a positionable mechanism

摘要

1,073,875. Positioning magnetic head assemblies; electric selective signalling. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 17, 1965 [Dec. 16, 1964], No. 48777/65. Headings G4H and G5R. [Also in Division H3] A magnetic head assembly (22, Fig. 1, not shown) is positioned radially on one of 512 tracks on a magnetic disc (10) by comparing the number of the desired track with the number of the actual track and using the error signal to correct the position. The disc may include a clock track (14) operating on a count base of 512 and feeding a binary counter (44, Fig. 2, not shown). A first digital quantity representing the desired track is stored in a register (40), and a second digital quantity representing the actual track is stored in a second register (42), the two registers feeding respective comparators (46 and 47) which produce output pulses each time the binary counter (44) reaches the corresponding digits. The output pulses are used to start and stop ramp generators which produce an output which is proportional to the magnitude and sense of the error and which is used to control a transducer positioning mechanism. The transducer mechanism may include a reference pattern sensor of magnetic or optical type for indicating the. actual track, or the reference track (14) may include radial variations by which the separate data track positions may be identified. The disc (10) may be one of a number of parallel discs in a multi-disc array mounted on a common shaft.