| 摘要 |
The contrast of an image reproduced by a television receiver is manually adjustable by means of a picture control potentiometer, and automatically adjustable by means of an ambient light responsive circuit. Automatic picture control is accomplished selectively, independent of the manual control setting, in accordance with a predetermined combination of ambient light and image brightness levels such that the contrast of bright images, rather than the contrast of all images, is automatically reduced in low ambient light. In a preferred embodiment such automatic picture control is accomplished by using the light responsive circuit to control the threshold operating level of an automatic kinescope beam current limiter of the receiver.
|
