Dimming circuit with saturated semiconductor device
US3936696A · kind A · utility
49Cited by
3References
31Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 27, 1973 |
| Grant date | Feb 3, 1976 |
| Priority date | — |
| Expiry date | Aug 27, 1993 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A fluorescent lamp is operated by a-c pulses having a pulse length sufficiently short that the lamp acts like slightly positive impedances. A pulse modulator which produces the pulses has a power transistor biased to saturation. However, varying the base drive of the saturated transistor causes a generally linear change in tube current to permit tube dimming and control. A servo circuit provides feedback control of the base drive to automatically compensate for variable effects to maintain constant tube lighting. Tube dimming is obtained by adjusting the feedback circuits of the servo.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.