| 摘要 |
PURPOSE:To prevent a black leveling by combining an emitter follower and a blanking transistor (TR) and connecting it to an output of a signal processing circuit so as to apply peak detection to the output. CONSTITUTION:When a black component in a video signal is detected by a peak detection diode 8, its output potential rises, while the potential is decreased in the absence of the black component. Through the operation above, in case of the presence of the black component, a diode 11 is cut off, the potential at a brightness control terminal 3 is unchanged and no diode 11 is turned on to decrease the potential of the brightness control terminal 3 thereby decreasing the brightness. Thus, the black leveling such as bringing a gray signal into a black level is avoided. That is, the black level correction is applied in a way that the brightness is decreased in case of a high APL and absence or black signal and that the luminance signal is not decreased in case of the pres ence of black signal.
|
