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:
Dec. 06, 1994
Filed:
Oct. 31, 1991
Steven C Brummette, Knoxville, TN (US);
William G Miller, Knoxville, TN (US);
James F Asbury, Memphis, TN (US);
William R Krenik, Garland, TX (US);
Norman L Culp, Plano, TX (US);
North American Philips Corporation, New York, NY (US);
Texas Instruments Inc., Dallas, TX (US);
Abstract
A clamp circuit including a clamping capacitor and a differential amplifier charge and discharge the clamping capacitor in accordance with the magnitude of difference signals applied to the differential amplifier's inverting and non-inverting inputs. The inverting input receives the voltage produced by the clamping capacitor. This voltage is digitized by an analog-to-digital converter (ADC) and is set to a reference voltage range by a voltage divider network. The ADC output signal is compared to a given reference level corresponding to a selected voltage in the reference voltage range to produce a difference output signal. This difference output signal is summed with the selected voltage in the reference voltage range and applied to the non-inverting input of the differential amplifier to produce a clamp voltage with substantially minimum offsets due to the amplifier, ADC and DAC. A clamp enable signal operates the clamping circuit during a blanking interval of a video signal applied to the clamping capacitor. A digital processing circuit of a television receiver receives the video signal clamped to the level of the clamp voltage. Instead of processing the video signal at the clamped level, a blanking signal code word is inserted in the clamped video signal to save memory. The video signal applied to the digital processing circuit is thus clamped to the voltage level by the inserted code word.