| 摘要 |
PURPOSE:To attain the automatic control of each servo control part and to simplify the control of a video tape recorder, by comparing the phases of a capstan and a cylinder motor and a digital control signal obtained from a speed signal with the standard data stored previously. CONSTITUTION:The capstan reference phase data obtained by converting digitally the capstan phase control signal of a reference level, i.e., a capstan phase control signal of 1/2 power supply voltage V of a servo circuit is stored in a reference value memory 41 for capstan phase consisting of a ROM. A coincidence circuit 40 compares the capstan detection phase data with the capstan reference phase data with the timing of the 1st clock pulse for capstan control. When the coincidence is obtained from said comparison and the capstan phase control voltage is set at an optimum level, the circuit 40 delivers a count stop signal to a counter 37. Thus the counter 37 stops its counting action. In this case, the count value of the counter 37, i.e., the data on designation of a capstan speed time constant is written and stored to a capstan phase control voltage memory 42 consisting of a RAM. Thus the control is through with the capstan phase control voltage. |
