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众所周知,如果电视机图像信号的灰度层次分明,彩色逼真,则图像看上去具有纵深、明快的感觉。为此,须把对应于图像黑色电平的消隐脉冲固定在某一规定的数量等级上,有了这个固定的消隐脉冲黑色电平作基础,电视信号的平均电平、白色电平,也就相对地保持在一定的数量等级上,从而能够正确地再现图像的灰度层次,保证在黑色电平附近的彩色逼真度得到充分体现。为达到上述目的,在电子线路中采用了消隐脉冲箝位电路。然而,这一方法是按一般情况考虑设计的,在其它情况下采用上述电路不能达到预期的目的。比如,当电视机在高亮度或强对比的情况下,
As we all know, if the gray scale of the television image signal is clear and the color is vivid, then the image looks deep and bright feeling. For this purpose, the blanking pulses corresponding to the black level of the image have to be fixed at a specified number of levels, with the fixed black level of the blanking pulse as the basis, the average level of the television signal, and the white level also It is relatively maintained at a certain level of quantity so that the grayscale level of the image can be correctly reproduced to ensure that the color fidelity around the black level is fully reflected. In order to achieve the above purpose, a blanking pulse clamp circuit is used in the electronic circuit. However, this method is designed for general use, and in other cases the use of the above circuit does not achieve its intended purpose. For example, when the television is in high brightness or strong contrast,