Overvoltage protection circuit
US5532894A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 11, 1994 |
| Grant date | Jul 2, 1996 |
| Priority date | — |
| Expiry date | Jul 11, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power supply is provided for a presentation system having a light source which allows for overdriving of the light source, but protects against transient surges on the input line when overdriving the light source. The power supply includes an input line connected to the external ac source, two output lines, and a relay selectively connecting the input line to one of the two output lines. The relay is indirectly controlled by a voltage sense circuit which converts the ac source voltage to a dc output voltage. The dc output voltage is examined to determine whether the input line is in a low- or high-voltage state, the high-voltage state corresponding to a surge on the line. The output lines are coupled to the load line (leading to the light source) in such a manner that the ac voltage source, when applied to the first output line, will produce a lower voltage at the lamp than that produced when the ac voltage source is applied to the second output line, thus overdriving the lamp when the relay connects the input line to the second output line. As long as the input line is not surging, i.e., while it is in the low-voltage state, the relay connects the input line to the second output…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.