| 摘要 |
PURPOSE:To obtain a stable color picture at all times without disturbing the phase of an index signal showing an electronic beam scanning position on the fluorescent surface, by enabling to obtain a correct index signal by executing the horizontal scanning two times. CONSTITUTION:In case of a beam index color television receiver of the linear sequential system, phase of an index signal which is obtained at the time of reproduction of red leads slightly comparing with its original phase, and phase of the index signal at the time of reproduction of green lags slightly comparing with its original phase. Also, at the time of reproduction of blue, since a beam current is cut off at the position of the index stripe, the index signal cannot be obtained. Therefore, a white W signal is applied as the first horizontal scanning to be executed immediately after the vertical synchronizing pulse, an optical index signal having correct phase is generated, the signal which has passed through the photoelectric conversion element 7 and the multiplying circuit 8 is divided into two, and one and the other are applied to the adding circuit 10 directly and through the 1H delay element 9, respectively. Accordingly, the following index signal becomes that which has been added with the index signal obtained by the previous horizontal scanning. |
