Vcr Servo Control Technology

The performance of servo control system determines the reliability and stability of VTR (Video Tape Recorder), and enables ultimately VTRs to record and replay video signal accurately. In this thesis, the servo control system of VTR is expounded from two points. One is the composing, function and principle of rotate speed and phase servo system of magnetic drum; the other is of capstan. To produce servo controlling signal, frequency splitting, sampling and retaining, and pulse duration modulating are decisive techniques. That is because the signal frequency splitting directly have an effect on the precision of sampling signal, and the sampling-pulse is modulated into a square wave signal that is fed back to control electric motor. For a VTR with long time recording performance, the capstan's rotate speed is totally determined by the frequency splitting of capstan's standard signal.On the theoretical base of VTR servo control system technique, this thesis describes the principle of a new model, ZN79-CMC. The self-designed tape-speed control system for model ZN79-CMC is introduced in detail. 20 sets of the new model have been produced in CHMAVC (China Hualu Matsushita AVC Co., Ltd) and they all pass through the quality examinations accord to the national technology standard of GB/T 15643-1995.