Cold-cathode fluorescent lamp multiple lamp current matching circuit
US8344658B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 2007 |
| Grant date | Jan 1, 2013 |
| Priority date | — |
| Expiry date | Aug 4, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/3927
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and circuit are provided for matching the brightness of a plurality of lamps driven by an AC drive current. The method may comprise the steps of: determining a brightness of each of said plurality of lamps, while said plurality of lamps are on, by using a current sensing device; selecting a first lamp having a lowest brightness from said plurality of lamps; and reducing a brightness of a second lamp to match said lowest brightness of the first lamp by interrupting the AC drive current in said scond lamp periodically for a predetermined number of half-cycles of said AC drive current. According to another implementation, a reference brightness maybe selected, or optionally a reference AC current level, and the method may reduce the drive current periodically so as to set the lamp brightness in relation to the reference brightness or optionally the reference AC current level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.