End of lamp life or false lamp detection circuit for an electronic ballast
US6008592A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 10, 1998 |
| Grant date | Dec 28, 1999 |
| Priority date | — |
| Expiry date | Jun 10, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/2985
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit which detects an end-of-lamp life or false lamp condition in a fluorescent lamp being driven by an electronic ballast by indirectly sensing total load power through an analog signal indicative of the operating frequency while controlling lamp power using phase control, and which deactivates the half-bridge driver circuit if the operating frequency exceeds a predetermined maximum frequency. Controlling the lamp power via phase control enables the simple detection of excessive lamp power due to either a symmetrical or an asymmetrical increase in lamp running voltage over the course of the life of the lamp. A simple resistor user-programmable interface which allows flexibility for setting different threshold levels for different ballast/lamp combinations. The circuit is easily implemented in an electronic ballast driver IC (e.g., the IR2158/2159), resulting in the elimination of existing high-voltage-sensing-component methods, reduction of PCB interconnects, and an increase in manufacturability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.