The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 1987
Filed:
Nov. 09, 1984
Wolfram Klemmer, Pfungstadt, DE;
Robert Bosch GmbH, Stuttgart, DE;
Abstract
A video signal as it comes from a camera is inverted and clamped to an adjustable voltage for the black level and then proceeds at an amplified level to a differential amplifier that applies a signal to the gate of an N-channel FET. The voltage source provides a positive voltage through a load resistor and the drain-source path of the FET in series, while the drain electrodes is fed back through the differential amplifier in phase opposition to the incoming video, causing the drain current to vary in the same way as the video signal voltage. The applied voltage and the load resistor are such as to operate the FET in its saturation region, with the result that the gate voltage which is the voltage at the output of the differential amplifier, has the desired square root curve characteristic for correcting the gradation distortion of the picture tube. If a P-channel FET is used, the polarity of the voltage supply is reversed and the video is applied to the differential amplifier non-invertedly and clamped low rather than high. A potentiometer adjusts the clamping level to obtain the desired value of the gradation slope (gamma).