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:
Feb. 03, 2009
Filed:
May. 30, 2007
Young-sik Lee, Seoul, KR;
Gye-hyun Cho, Bucheon, KR;
Young-Sik Lee, Seoul, KR;
Gye-Hyun Cho, Bucheon, KR;
Fairchild Korea Semiconductor, Ltd., Bucheon-Si, KR;
Abstract
A circuit for detecting the end of life of a fluorescent lamp is provided. In this circuit, a rectifier rectifies a voltage signal detected from a ballast. A phase detector detects the phase of the voltage signal and outputs at least one phase detection signal. A signal separator separates the rectified voltage on a phase basis to generate first and second voltage signals in response to the phase detection signal. A first maximum level detector detects the maximum level of the first voltage signal. A second maximum level detector detects the maximum level of the second voltage signal. A first comparison unit compares the first and second maximum levels and detects whether or not the difference is higher than a predetermined allowable level. A controller determines whether or not the fluorescent lamp is at the end of life in response to the detection from the first comparison unit.