| 摘要 |
PURPOSE:To eliminate the need for the readjustment against a phase fluctuation caused by environmental changes and the initial adjustment and to keep on optimum state, by detecting the phase difference between a character signal and a sampling clock and adjusting the phase of the sampling clock in response to the detected phase difference. CONSTITUTION:A mutliplex character signal is extracted from a video signal with a character signal extracting means 11 and applied to an S-P converting circuit 6, and also to a synchronizing pulse generating circuit 3, a phase comparator 4 and a phase adjusting means 5. Further, a sampling clock generating means 2 counts down a high frequency signal to generate a sampling pulse, and a load signal 31 synchronized with the character signal at the circuit 3 is applied to the means 2. Further, the phase difference between the sampling clock 23 and the character signal is detected at a comparator 4, an output signal corresponding to this phase difference is converted into a digital number at the means 5 at each field, the number is applied to the means 2 as an adjusting signal so as to make the phase of the character signal and the sampling clock 23 coincident with each other. |
