Electronic ballast having open circuit in output
US6720741B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 2002 |
| Grant date | Apr 13, 2004 |
| Priority date | — |
| Expiry date | Feb 1, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/2851
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Gas discharge lamps may conduct current from the common rail to earthen ground through a fixture containing the lamps. A transistor is coupled in series in the current path to the common rail. When the ballast is placed in a quiescent state, the transistor is rendered non-conducting, thereby solating the lamps from the common rail and preventing flicker. In accordance with another aspect of the invention, the control electrode of the transistor is coupled to a source of low voltage and the transistor is rendered non-conducting when the source of low voltage is turned off. The lamps can also be isolated from the common rail by using a semiconductor switch in the rectifier section or by referencing the output of the inverter to the high voltage rail.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.