| 摘要 |
A background-picture compensating circuit using an OSD signal for performing a half tone function without requiring a half tone circuit includes a video signal processor for separating a received composite video signal into R, G, B signals, a microcomputer for muting the R, G, B outputs of the video signal processor upon the receipt of an OSD character display key input to supply a signal for a background picture of the OSD character, and a CRT driver for amplifying respective R, G, B signals from the video signal processor or microcomputer to provide the amplified signals to a cathode of a CRT, in which the microcomputer supplies pulses of a high frequency in response to an input of the signal for the background picture of the OSD character to swiftly repeat On/Off operation of the output of the R, G, B signals of the video signal processor on the background picture of the OSD character for making the background picture level lower than a surrounding level, thereby enabling a display of both an original picture covered by the background picture and the OSD character, simultaneously without any additional half tone circuit.
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