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. 07, 2006
Filed:
Aug. 09, 2004
Charles Guan, San Francisco, CA (US);
Charles Guan, San Francisco, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A method and circuit for digitally controlled vertical C linearity correction with constant start and end points without using an AGC. A squared voltage and a negative squared voltage are added as a correction voltage to a sawtooth-shaped ramping voltage that is employed to sweep an electron beam across a display. Line spacing toward the edges of a screen are maintained equal as a result enabling a uniform presentation of a picture on a non-spherical display. A digitally controlled attenuator determines a correction coefficient for correction voltages. The correction voltage is also processed by a sample-and-hold circuit to obtain a peak squared voltage. The peak squared voltage is then compared to a DC reference voltage and an offset adjustment current determined, based on a result of the comparison. The correction voltage is then added to the ramping voltage, which is also shifted by the offset amount.