Circuit for detecting end of life of fluorescent lamp
US7486029B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 2007 |
| Grant date | Feb 3, 2009 |
| Priority date | — |
| Expiry date | Jul 25, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/44
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.