| 摘要 |
PURPOSE:To prevent the bad influence upon the display screen of a CRT, by using a round CRT to deflect the raster scanning and blanking four corners of the video signal in respect to a scanning part overflowed from the display screen of the CRT. CONSTITUTION:The output of an X address register 12 to which an X clock pulse XCL is inputted is transferred to a memory 11, and also compared with the output of an up/down counter 16 by a comparator 14, and the output of the comparator 14 is inputted to an FF18. Similarly, the output of the register 12 is compared with the output of an up/down counter 17 by a comparator 15, and the output of the comparator 15 is transferred to the FF18 through an OR gate 19. A gate 20 is opened by the output Q of the FF18, and a radar video signal RVS read out from the memory 11 is outputted. The output Q of the FF18 is reduced to an unblanking gate UBG. A horizontal synchronizing pulse HD is inputted to counters 16 and 17 to control the blanking part at four corners of the video signal. |
