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:
Feb. 06, 1990
Filed:
Feb. 15, 1989
William G Miller, Knoxville, TN (US);
North American Philips Consumer Electronics Corp., Knoxville, TN (US);
Abstract
The coring circuit in a luminance processor has a characteristic which starts at the O input/O output point and extends linearly in both a positive and negative direction. The characteristic is implemented by a linear amplifier from which the input luminance signal is blocked until it has reached a predetermined threshold amplitude. Low amplitude, high frequency noise is therefore removed without causing overpeaking at high transition levels. The coating stage is preceded in the signal processor by a circuit which furnishes a peaking signal whose rise and fall time are independent of the amplitude of the transition. This circuit is implemented by feeding back the peaked luminance signal through a first filter which has a cut-off at 4 MHz and therefore furnishes a signal responsive both to the change in amplitude and the rate of change of that amplitude, and a second filter whose output is proportional only to the change in amplitude. The output of the second filter is subtracted from that of the first, so that the resultant gain control signal varies only as a function of the transition time. This gain control signal is then applied to a gain control amplifier in the forward loop. The feedback operates to keep the transition times constant.