| 摘要 |
PROBLEM TO BE SOLVED: To improve the sharpness by selectively switching a frequency response characteristic of a filter in response to a kind of visual contents of a video signal and giving a correction signal with an obtained frequency spectrum to a deflection magnetic field generator to modulate a beam scanning speed. SOLUTION: A switch control signal 28 is used to select a signal delay element 20a of a filter stage 20 when a signal Y including visual contents of an on-screen display character is a high definition ATSC video signal and is used to select both signal delay elements 20a, 20e when the signal Y is an NTSC video signal that is not contents of the on-screen display character. A subtractor 27 subtracts a signal selected from the filter stage 20 from the signal Y at a terminal 27b to generate a differentiated signal 25. This signal 25 is given to a D/A converter 21, which provides an output of a scan speed modulation signal SVM-OUT and it is coupled with a coil L1 provided to a CRT 36 via an LP filter 23 and an AMP 24.
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