SERVOSYSTEM FUER EINEN MOTOR

摘要

A servo system for a motor 10, such as the drum motor of a VTR, has a memory 24 which stores error data for a plurality of angular positions of the motor sensed by a detector 11. The error data is used by circuits 26, 28 to correct speed and phase measurements of the motor several times for each revolution and compensates for errors of the detector 11, e.g. caused by eccentricity. A system in which the speed of the motor is measured from the gradient of sinusoidal signals output from the detector at low speeds is also described, the signals being gain controlled if necessary.