D.C. MOTOR SPEED CONTROL CIRCUIT

摘要

In a helical scan video tape recorder, a capstan motor is speed-controlled in response to a command frequency of a command signal under a special reproducing mode called a SEARCH MODE. A speed servo loop for the capstan motor for this purpose includes a pair of pulse converters and a pair of integrating circuits for comparing the command signal and a rotation signal generated by a frequency generator attached to the capstan motor. A time constant of the integrating circuit for the command signal path is selected to be smaller than that of the integrating circuit for the rotation signal, so that the capstan motor is driven in a pulse drive mode below a predetermined speed.