| 摘要 |
PROBLEM TO BE SOLVED: To stably conduct automatic phase adjustment for a dot clock the being a sampling clock of analog video signals without being adversely affected by noise components of the signals. SOLUTION: A noise mask section 15 detects a maximum value of the fluctuation of digital signals in a blanking period of analog video input signals as a noise level value, determines a value that is not lower than the noise level value, as a mask signal value and masks noise components included in the digital signals by the mask signals. A phase detecting section 16 outputs a phase detection result based on the digital signals in which noise components are masked. A CPU 13 conducts a phase setting having several steps in a PLL circuit 14, stores the phase detection result of the phase of the circuit 14 at each step, determines the phase, at which the result becomes a maximum, as an optimum and sets the optimum phase in the circuit 14. |
