Circuit for detecting near or below resonance operation of a fluorescent lamp driven by half-bridge circuit
US6331755A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1998 |
| Grant date | Dec 18, 2001 |
| Priority date | — |
| Expiry date | Jun 10, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/2986
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit which detects near or below resonance operation of a fluorescent lamp being driven with a half-bridge circuit and which deactivates the half-bridge circuit before any damage to the circuit can result. In the circuit of the present invention, the voltage across a sense resistor disposed either the lower transistor switch and ground, or between the lower lamp filament and ground, is compared against a predetermined reference voltage to generate an output comparison signal. The output comparison signal is gated to the turn-off edge of the lower MOSFET (in the case of the sense resistor disposed between the lower MOSFET and ground) or to the turn-off edge of the upper MOSFET (in the case of the sense resistor between the lower lamp filament and ground) to generate a signal for shutting down the half-bridge circuit in the event of near or below resonance operation of the lamp resonant circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.