Apparatus and method for controlling the capstan motor of the video

Abstract

An apparatus and a method for controlling automatically a fine-slow in a VCR comprises a servo control device for controlling an operation of a capstan motor, a control head for detecting a control pulse from a video tape and applying the detected control pulse to the servo control device, a Schmidt trigger circuit for Schmidt-wave shaping the detected control pulse from the control head, an envelope detector for receiving a playback radio frequency signal and detecting an envelope signal of DC component from the received signal, and a microcomputer for sampling the detected envelope signal from the envelope detector in intervals of a head switching signal of the front and rear of the control pulse in a slow playback interval, A/D-converting the sampled values, comparing the digital sampled values with each other and applying slow control data based on the comparison of the digital sampled values to the servo control device to control shift of the control pulse, the slow control data being data for controlling the capstan motor in a slow mode. The microcomputer compares the sampled values with each other and control shift of the control pulse in a positive (+) or negative (-) direction in accordance with the compared result until the sampled values are the same.