Ballast circuit for a gas-discharge lamp having a filament drive circuit with monostable control
US8232727B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 12, 2010 |
| Grant date | Jul 31, 2012 |
| Priority date | — |
| Expiry date | Feb 4, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/295
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic ballast circuit includes a filament drive circuit that can adjust the pulse width of a pulsed heating signal in accordance with the lamp current to a gas-discharge lamp. A logic device, such as an SR flip-flop, is used to control a switch that is coupled to the primary winding of a filament drive transformer coupled to the lamp filaments. The logic device opens and closes the switch device to generate the pulses of the pulsed heating signal and thus controls the pulse width of the pulses. A clock signal triggers logic device to start a pulse while the end of the pulse is determined by a signal level across a resistor in series with the primary winding of filament drive transformer. Once this signal level is at or above a threshold level, logic device switches the switch device to end the pulse.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.