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. 11, 1992
Filed:
Jul. 16, 1991
Arnoldus J Boudewijns, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
The frequency of a local oscillator is maintained within a small frequency window around any one of a number of reference frequencies so that it can lock onto the frequency of an incoming color burst (CHRM). The oscillator (10) may be a current-controlled oscillator. Its control input is switched via a fet (32) to a capacitor (20) charged to a voltage level which will, when connected to the oscillator control input, result in the correct oscillator frequency (Fo). The connection to this capacitor (20) is made when the charge on either one of two control capacitors (22,24) exceeds a threshold value. The threshold values are exceeded when the local oscillator frequency (Fo) is respectively greater than or less than the reference frequency (Fr) by a predetermined frequency difference.