| 摘要 |
PROBLEM TO BE SOLVED: To provide an image quality enhancement circuit capable of bringing effect of sufficient vertical contour correction even on a signal with a large APL (Average Picture Level) by adding a comparatively simple circuit. SOLUTION: The image quality enhancement circuit includes: a vertical contour correction circuit 22 for correcting a contour of a received video signal; a gain and loopback point control circuit 23 for controlling a gain of a contour correction signal and a loopback point in response to a control signal; an ABCL (Automatic Brightness Contrast Limiter) circuit 25 for limiting a cathode current as to a video signal whose APL level is a prescribed value or over on the basis of a detected value (ABCL control voltage) of a cathode current of a CRT; and a control means 26 for generating the control signal on the basis of the detected value of the ABCL circuit 25 to control the gain and loopback point control circuit 23. The setting of vertical contour correction is switched depending on when the APL is high or low on the basis of the detected value of an ABCL voltage so as to enhance the reduction in the effect of vertical contour correction at input of the high APL signal. COPYRIGHT: (C)2003,JPO
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