| 摘要 |
PURPOSE:To realize the automatic centering, by using an inexpensive delay circuit of a narrow band. CONSTITUTION:A green output video signal supplied from an input terminal 11G and a red or blue output video signal from a switch 15 are applied to a difference circuit 23. Thus the 1st difference signal E is obtained. At the same time, a signal A given from the terminal 11G is supplied to a difference circuit 25 through a delay circuit 24. Thus the 2nd difference signal B is obtained. Furthermore a signal C from the switch 15 is supplied to a difference circuit 27 through a delay circuit 26. Thus the 3rd difference signal D is obtained. These signals B and D are supplied to a sum circuit 28 to obtain a sum signal F. Then a negative or positive signal G is obtained with an upward or downward shift respectively by supplying signals E and F to a multiplying circuit 17 since these signals have opposite phases to each other or the same phase. The signal G is sampled with a signal H of a full-wave rectifying circuit 20, and a DC signal I is delivered 21. Then the automatic centering is possible with use of the signal I. |
