Automatic brightness control circuit employing a closed control

Details Automatic brightness control circuit employing a closed control Automatic brightness control circuit employing a closed control

1978-03-22

1979-03-06

Martin, John C.

Facsimile and static presentation processing

Static presentation processing

Attribute control

358168, 358172, H04N 516, H04N 9535

Patent

active

041433980

ABSTRACT:
Brightness control apparatus in a video system employing a sample and hold circuit including a charge storage capacitor. The sample and hold circuit forms a closed control loop with a signal processing channel, and is keyed during periodic blanking intervals of the video signal to sample the magnitude of a reference voltage and a brightness representative blanking level of the video signal. The sample and hold circuit provides an output control signal indicative of the voltage difference between the reference voltage and the blanking level. The control signal is applied to the signal channel for translating the blanking level in a direction to minimize the voltage difference, so that a desired relationship between the reference voltage and the blanking level is preserved. In a preferred embodiment, a diode coupled between a sampling transistor and the capacitor assures that the capacitor is not charged improperly in the event the normal current conducting mode of the transistor is disrupted in the presence of large amplitude video signals, thereby preventing operation of the closed control loop from being disrupted.

REFERENCES:
patent: 3588341 (1971-06-01), Hansen
patent: 3597540 (1971-08-01), MacIntyre
patent: 3885093 (1975-05-01), Mooney
patent: 3985954 (1976-10-01), Kuniyoshi et al.

Affiliated with

Also associated with

Rating

Automatic brightness control circuit employing a closed control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Automatic brightness control circuit employing a closed control , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic brightness control circuit employing a closed control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-924171