Tracking control circuit using a delayed tach signal

Claim 1

A video tape recorder in which a video signal is recorded on a magnetic tape as a plurality of skewed tracks by a rotary magnetic head which is rotated in synchronism with a frame frequency signal contained in the video signal and in which a recorded video signal is reproduced by the rotary magnetic head from the magnetic tape on which a control signal synchronized with the frame frequency is recorded comprising: a. first and second rotary magnetic heads mounted on a support member and spaced apart by 180° and a tape guide drum for guiding the magnetic tape about the surface of the drum so that the rotary magnetic heads scan the tape; b. a capstan for transporting the magnetic tape about the drum; c. means for driving the capstan and head driving means for driving the rotary magnetic head; d. a control signal magnetic head operable during a signal recording operation to record said control signal onto said magnetic tape and operable during a signal reproducing operation to reproduce the control signal from the magnetic tape; e. a first transducer for detecting the position of the rotary magnetic heads and for generating an output signal when one of the rotary magnetic heads rotates into an initial tape contact position whereat the rotary magnetic head arrives proximate a recorded area corresponding to that associated with a reproduced control signal; and a second transducer angularly displaced from said first transducer by a predetermined amount for detecting the position of the rotary magnetic head and for generating a second output signal time displaced from said first output signal when the other rotary magnetic head is rotated into an initial tape contact position; f. variable delay means connected to said second transducer for imparting a selectively variable time delay to the second output signal, the total time delay imparted to said second output signal being no greater than the time separating said first and second output signals; g. phase comparator means for determining the phase difference between signals applied thereto, said phase comparator means including a first input and a second input; h. manually operable switch means operable during a signal recording operation to supply the phase comparator means with a signal synchronized with the frame frequency signal contained in a received video signal and to couple the first transducer to the phase comparator means, and operable during a signal reproducing operation in a first mode to couple the control signal magnetic head and the first transducer to the phase comparator, and being further operable during a signal reproducing operation in a second mode to couple the control signal magnetic head and the variably delayed second output signal to the phase comparator; and i. phase control means for adjusting the driving phase of at least one of said driving means in accordance with the output signal produced by the phase comparator means.