Lamp control scheme for rapid warmup of fluorescent lamp in office equipment
US5907742A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 1997 |
| Grant date | May 25, 1999 |
| Priority date | — |
| Expiry date | Mar 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B41/386
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A lamp control scheme for rapid warmup of a cold cathode fluorescent lamp, to minimize the warmup time while maintaining long lamp service light. The lamp is over-driven with high current for up to a predetermined time limit to accelerate mercury vaporization. The drive current is then reduced to a normal level. The scanner light output is monitored by a sensor circuit, and the system waits until the light output exceeds a minimum output and the light profile is sufficiently stable. The scanner is then calibrated to a white reference, and the closed loop control of the signal level is activated. The scan or copy process is now performed, and the light level control is deactivated as needed. Thereafter, between uses the lower lamp current is 40% of normal level to keep the lamp warm while extending the life of the product. If the product has not been used in a long time, the lamp is turned off.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.