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. 12, 2000
Filed:
Oct. 15, 1998
Katsunori Kumasaka, Soma, JP;
Hiroyuki Sato, Sendai, JP;
Tokin Corporation, Miyagi, JP;
Abstract
To provide a cold-cathode tube lighting circuit which quickly and smoothly carries out lighting of a cold-cathode tube and prevents damage of a piezoelectric transformer as an inverter transform in the lighting circuit, the lighting circuit is provided with a protection circuit for detecting a primary current of the piezoelectric transformer. The protection circuit stops operation of an oscillator for driving the piezoelectric transformer when the primary current is excessive. The protection circuit may be provided to detect excess of a secondary voltage of the piezoelectric transformer. When the cold-cathode tube is used as a backlight for a liquid crystal display driven by the use of a scanning frequency, a dimmer circuit is used for producing a dimmer signal with a dimmer frequency and a controlled duty ratio given by a manual selector for controlling start and stop of the oscillator according to a desired brightness of the backlight. The dimmer frequency is obtained from frequency division of the scanning frequency. The controlled duty ratio is also modified corresponding to the divided frequency.