Signal generating circuit for ballast control of discharge lamps
US4952848A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 5, 1988 |
| Grant date | Aug 28, 1990 |
| Priority date | — |
| Expiry date | Jul 5, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A ballast control apparatus for an electric discharge lamp comprises a first series circuit including a first winding of an AC supply voltage transformer, a first winding of a ballast transformer, a lamp current sensing resistor and the lamp. A current sensing transformer has a first winding parallel to the resistor. A second winding of the supply voltage transformer, the ballast transformer and the current sensing transformer are connected in a second series circuit. A signal voltage proportional to lamp power is derived by adding together the voltages induced in the three series-connected second windings. A second signal voltage proportional to lamp voltage is derived across the series combination of the second windings of the ballast transformer and the supply voltage transformer. The voltage induced in the second winding of the current sensing transformer is proportional to lamp current. A signal voltage indicative of the condition of the lamp load can be derived across the second winding of the ballast transformer. These three signal voltages are used to control a DC/AC inverter that energizes the lamp via the supply voltage transformer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.