| 摘要 |
PROBLEM TO BE SOLVED: To provide a vertical synchronous signal detecting circuit for liquid crystal monitor, etc., capable of surely fetching a vertical synchronous signal, and performing a screen display with little fluctuation. SOLUTION: This circuit is formed of a horizontal counter 2, a horizontal synchronous signal width register 3, a comparator 4, and a vertical synchronous signal acquiring circuit 5. A vertical synchronous signal is fetched when the same period as the period where a horizontal synchronous signal is in H-level further passed after this period. Namely, the vertical synchronous signal is fetched in the position twice the horizontal synchronous signal width, thereby, it can be surely fetched.
|
