| 摘要 |
PURPOSE:To reduce the phase shift of a vertical synchronizing pulse and to reduce an error by generating a mask pulse from a horizontal synchronizing process mask circuit to stop the actuation of a phase wave detecting circuit for a period of a vertical synchronizing signal and equivalent pulses before and after said synchronizing signal. CONSTITUTION:The oscillation output of a voltage control oscillator is divided by 1/16 divider 31 of a synchronizing signal reproducing circuit, and this division output is divided by a 1/2 divider 32 to produce horizontal synchronizing pulses. At the same time, the outputs of the divider 31 are counted by a vertical counter 33. Then the vertical synchronizing pulses are produced from a vertical synchronism detecting circuit 34. The output of the circuit 34 is applied to a reset pulse producing circuit 35, and the counter 33 is reset by the output of the circuit 35. A horizontal synchronizing process mask circuit 36 is provided in relation to the counter 33. The circuit 36 produces a mask pulse MKP stopping a phase wave detecting circuit 37. This reduces the position shift of the vertical synchronizing pulse as well as the error. |
