| 摘要 |
PURPOSE:To eliminate the need for manual operation and to avoid troublesome operation by detecting the lightness of surrounding, selecting a voltage of a grid electrode in response to the lightness and adjusting it automatically. CONSTITUTION:A circuit 11 detecting the lightness of surrounding generates a detection signal 12 whose value differs from the lightness of surrounding. The detection signal 12 is fed to a brightness adjusting signal generator 13. The generator 13 sections the brightness adjustment to some stages, a brightness adjusting signal 14 is changed depending on the range of lightness to apply brightness adjustment stepwise. Then a voltage signal 5 in response to the signal value is generated by a brightness controller 4 and fed to the grid electrode of a picture tube 2. Thus, no manual operation is required and remote control is attained.
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