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:
May. 13, 2008
Filed:
Feb. 28, 2006
Nobuaki Honbo, Kawasaki, JP;
Nobuaki Honbo, Kawasaki, JP;
NEC LCD Technologies, Ltd., Kanagawa, JP;
Abstract
A cold cathode tube lighting device is provided which is capable of obtaining stable luminance when a cold cathode tube is driven by applying voltages to input terminals on both ends of the cold cathode tube. A first current flowing through each of transformer secondary sides of transformers is detected by a tube current detecting circuit from a low-voltage side of each of the transformer secondary sides and a second current flowing through each of resonance capacitors is detected by the tube current detecting circuit and a difference between the first current and the second current is calculated for every separately-excited inverter and, based on the difference, a tube current of the cold cathode tube is obtained and frequencies of driving pulse voltages are changed by a voltage controlling oscillator for setting so that the tube current maintains a predetermined value.