Light dimmer for solid state ballast
US4414493A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 6, 1981 |
| Grant date | Nov 8, 1983 |
| Priority date | — |
| Expiry date | Oct 6, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A system for controlling the current in a solid state, high frequency ballast energizing a gaseous discharge lamp for providing light dimming therein is disclosed. The ballast includes a thyristor/capacitor inverter bridge for generating the lamp current which is regulated by a commutation circuit synchronized with zero crossings of the thyristor current. Lamp current and voltage level signals are fed back to the commutation circuit for proper lamp current regulation. A dimming signal is added to either the lamp current feedback or voltage feedback signal and this composite signal is provided to the lamp current regulator in varying the bias thereof for selectively controlling light intensity. Dimming may be accomplished either manually by means of a rotatable switch having an output which varies linearly with shaft rotation or automatically by means of an ambient light level sensor to provide a predetermined output light level which may be manually adjusted. A common isolated control line facilitates photosensing control in a multiple ballast/light system with inter-ballast and ground isolation provided by optoisolators. In a preferred embodiment, a user adjustable balanced bridge…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.