High frequency ballast for gaseous discharge lamps
US4873471A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 8, 1987 |
| Grant date | Oct 10, 1989 |
| Priority date | — |
| Expiry date | Oct 8, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic frequency inverter circuit receives input electrical power at a lower frequency and energizes a load circuit including gaseous discharge lamps in a range of higher frequencies. First and second semiconductors are operated alternatively by a logic circuit in current mode control such that the switches operate at the high frequency range and the frequency of current in the load circuit varies as the magnitude of said source voltage varies. The load circuit has an impedance which varies with frequency such that the peak amplitude of the load current remains substantially constant despite variations in the magnitude of said source voltage to achieve a desirable crest factor for the lamp current. A high current limit circuit rapidly turns off the switches when excessively high current begins to flow through the switches. Low voltage is supplied in port from the high frequency current. Normal operation is ensured during start-up, for reduced line voltage and for a semiconductor chip embodiment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.