Video tape recorder method and apparatus

Abstract

Motor drive and servo systems particularly useful in high quality broadcast video tape recorders. A sine/cosine drive for a brushless DC motor permits high motor efficiency in a system adapted for use in a servo loop. A technique for phase locking a pair of frequency related phase locked control variable signals to a pair of frequency related reference signals, horizontal and vertical sync signals, for example, provides the advantages and precision of closed loop correction at widely variable correction rates. More accurate tape shuttling in a VTR is provided by running a DC motor in a phase locked loop as a synchronous motor and more accurate stopping of the tape is provided by comparing the capstan speed to ground in a closed loop. Improved tape tension control in the head area is provided by a pair of vacuum columns controlled by an error signal derived from the peak-to-peak tension error.

Dependencies are inferred from the claim text.