| 摘要 |
<p>PURPOSE:To generate a clock with less jitters and a clock in synchronizing with a horizontal synchronizing signal even at broadcasting in white/black by switching a clock switching means with the aid of a color burst detection signal. CONSTITUTION:A switching signal 68 switches simultaneously switches of switching circuits 60 and 67. When the switches are switched to the upper side, the circuit 60 selects a horizontal synchronizing signal and outputs it as an output signal, while the circuit 67 selects an output signal of a 910-frequency divider circuit 65. Then the selected signal turns out to be a phase locked loop for clocking the horizontal synchronizing signal. When the switches of the circuits 60 and 67 are switched to the lower side, the circuit 60 selects a and outputs a color burst signal, while the circuit 67 selects an output signal of a 4-frequency divider circuit 66. Then the selected signal turns out to be phase locked loop for clocking the color brust signal. In terms of the switching signal 68, the switches of the circuits 60 and 67 are switched to the lower side and to the upper side at color broadcasting and white/black one, respectively, and data is written to a latch 61 from a CPU.</p> |
