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:
Sep. 26, 1995
Filed:
Feb. 05, 1993
Charles M White, Noblesville, IN (US);
Thomas D Gurley, Indianapolis, IN (US);
Thomson Consumer Electronics, Inc., Indianapolis, IN (US);
Abstract
A driver for a cathode ray tube includes a black level compensation circuit which generates an offset voltage which tracks the current flowing to the output of the driver and therefore the average picture level (APL). The offset voltage is added as a component of the output voltage so as to increasingly shift the output voltage toward black as the APL increases. This compensates for CRT gamma non-linearities and for light scattering effects which might otherwise cause the loss of perceived detail and sharpness in dark areas of a high APL image. In the disclosed embodiment, the driver comprises a cascode amplifier and the offset voltage generating element includes a capacitively bypassed resistor connected in a reference voltage network connected to the emitter circuit of the lower (common emitter configured) transistor of the cascode amplilfier.