Apparatus for controlling the brightness of a magnetron-excited lamp
US5438242A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 1993 |
| Grant date | Aug 1, 1995 |
| Priority date | — |
| Expiry date | Jun 24, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power supply for providing a stable operating current to a magnetron-excited lamp. The power supply includes a DC to DC inverter for driving a primary winding of a high voltage transformer. The DC to DC inverter has a circuit including two pairs of switching elements for connecting a DC voltage supply to the primary winding. During each half of the switching cycle, one of the switching elements is pulse width modulated while the other remains on for a substantially fixed period of time. During the second half of the cycle, the remaining pair operates so that one switching device is on for a pulse width modulated period of time, and the other is on a substantially constant amount of time. The on time for the pulse width modulated switching elements is defined by an input voltage setting representing a desired brightness level for the lamp, the output magnetron current, and a representative of the integral of the current flowing through the primary of the inverter transformer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.