Electronic circuit for operating a HID lamp, and image projector
US6779896B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 23, 2002 |
| Grant date | Aug 24, 2004 |
| Priority date | — |
| Expiry date | Jul 23, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B47/20
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic circuit for operating a High Intensity Discharge (HID) lamp, in particular a Ultra High Pressure (UHP) lamp, such as those preferably used in image projectors. The circuit comprises a lamp ballast for offering a controlled lamp current for operating the HID lamp and a brightness sensor for generating and providing a sensor signal which represents the brightness of the light applied by the lamp to the image generator. The lamp ballast controls the lamp current such that the brightness of the light of the lamp remains constant. Brightness control is made possible throughout the entire operational life of the lamp, and the use of sensors of simple construction is made possible by an incorporation within the electric circuit of a filter that high-pass filters the sensor signal before it is supplied as a control signal to the lamp ballast.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.