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:
Oct. 13, 1998
Filed:
Jul. 20, 1995
Richard D Cappels, San Jose, CA (US);
Apple Computer, Inc., Cupertino, CA (US);
Abstract
A system and method of compensating for the effects of aging of phosphors and faceplate upon color accuracy in cathode ray tubes, wherein beam current measurements are made upon individual cathodes of a cathode ray tube to sample the individual beam currents at periodic intervals. The sum-totals of the individual beam current measurements are then stored in a non-volatile memory location. Correction factors are calculated for both luminous efficiency degradation and for deviations in hue, based on the stored sum-total beam current measurements in combination with empirically-derived formulae. These correction factors are then used to calculate corrected tristimulus values X, Y, and Z. The corrected tristimulus values are used to calculate the amount of beam current necessary to compensate for color degradation of the cathode ray tube. Finally, the respective gains of the video amplifiers are adjusted to achieve the amount of beam current necessary to compensate for the effects of aging of the cathode ray tube.