| 摘要 |
PURPOSE:To limit automatically the luminance at receiving of an RGB signal by providing an RGB contrast variable circuit and a DC level variable circuit changing a DC level at an RGB contrast variable terminal in response to the increase in an anode current of a picture tube so as to reduce the contrast of the RGB video. CONSTITUTION:In receiving a video having stricking RGB contrast, a voltage at a connecting point TPD1 changes from a positive to a negative value when a beam current of a prescribed value or over flows and a diode 13 is conductive. When an RGB automatic luminance limit control signal is applied to a base of a transistor(TR) 14 (other than the super pause mode), TR9, 14 are turned on, a voltage at an RGB contrast variable terminal T1 is decreased, an RGB output level is decreased and the luminance of video is reduced. In receiving the super pause, a base of TR14 goes to low potential, the TR9, 14 are turned off and the RGB automatic luminance limit is not operated. |
