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. 17, 1999
Filed:
Apr. 14, 1998
Eiji Nakagawa, Ukyo-ku, JP;
Sachito Horiuchi, Ukyo-ku, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
A liquid crystal back light illuminating device includes a driving circuit which receives a first value voltage at light-on starting. The device drives a voltage stepping up circuit and lights on a cold cathode tube with a stepped-up high voltage. Thereafter, it receives a second value voltage, drives the voltage stepping up circuit and continues the lighting-on of the cold cathode tube with a lower stepped-up voltage than the former stepped-up high voltage. A slowly varying voltage which is obtained by charging a capacitor with a small current is applied to the driving circuit via an amplifier and a switch circuit. When the varying output voltage comes close to the second value voltage beyond a predetermined value, the switch circuit switches to the second value voltage. Thereby, flickering of the cold cathode tube at the time of switching the light-on condition is prevented.