| 摘要 |
PURPOSE:To decrease the speed of A/D conversion remarkably while improving horizontal linearity by writing an information signal of horizontal linearity in a memory after A/D conversion, by D/A-converting a signal read from the memory and then by supplying a D/A conversion output to the method of correcting horizontal linearity. CONSTITUTION:Information on horizontal linearity is written in RAM71 after A/D converted by A/D converter 70 made of a sequential comparative type so that it will sequentially be set, bit by bit, from the highest order bit among lines at intervals of one field or a few frames continuing in terms of time. An information signal, read from RAM71, is latched by latch circuit 72 and, after D/A-converted by D/A converter 73, supplied to correcting horizontal deflecting method 90 by way of switch circuit 74 and driving circuit 28. Then, the horizontal linearity is corrected by deflecting method 90 to nearly equalize scanning speeds of electron beams, so that frequencies of index signals will nearly be constant. |
