Ballast control device
US4037148A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1975 |
| Grant date | Jul 19, 1977 |
| Priority date | — |
| Expiry date | Aug 15, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F1/66
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Ballast control circuit for regulating power supply to high intensity discharge lamp by compensating for changes in line voltage and lamp voltage. Current flowing in power supply to lamp is controlled by a circuit including a triac inductively coupled to the supply line, a triggering circuit for firing the triac at predetermined time intervals for phase control of the alternating current supply to the lamp, a non-linear amplifier circuit for controlling the phase interval of firing of the triac, a synchronizing circuit for synchronizing the triac firing with the lamp voltage, and a voltage reference circuit for controlling the operation of the non-linear amplifier circuit in response to changes in the lamp voltage. A power supply circuit is connected to the alternating current supply for supplying direct current with both regulated and unregulated voltage to the above-described control circuit. The circuit operates to automatically provide constant power to the lamp to maintain desired lamp brightness even with changes in lamp voltage and varying line voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.