| 摘要 |
PURPOSE:To improve the image contrast by cutting the both edge parts of a video signal of a scan line in order to set a part projecting on an inner wall surface of the funnel of a deflected electronic beam at a cut-off level. CONSTITUTION:The signal processing is carried out to shorten the display time of a scan line at the upper and lower end parts of a raster based on the scan line of the display time a0 of a scan line 9 set when the light is emitted evenly on the entire raster. Under such conditions, DELTAS<= (OS-100) (1/100) (4/3) (1/2) (1/Y) y<2> is satisfied when the cut width is set at DELTAS at one of both sides of the display time together with the height of an effective screen set at Y, the over-scan rate set at OS%, and the vertical coordinates set at y with the center of the screen defined as an original point respectively. Then the raster formed by a processed video input signal is identical with a raster formed when the outside part is deleted from a single dot line drawn at a corner part of the outside raster of an effective screen 10. Therefore, the electronic beams projecting on the inner wall surface of a funnel are eliminated. |
