| US 7,521,876 B2 | ||
| Electronic ballast with lamp type determination | ||
| William L. Keith, Lake in the Hills, Ill. (US); George L. Grouev, Arlington Heights, Ill. (US); and Kent E. Crouse, Carpentersville, Ill. (US) | ||
| Assigned to Koninlijke Philips Electronics, N.V., Eindhoven (Netherlands) | ||
| Appl. No. 10/596,330 PCT Filed Dec. 09, 2004, PCT No. PCT/IB2004/052736 § 371(c)(1), (2), (4) Date Jun. 09, 2006, PCT Pub. No. WO2005/060319, PCT Pub. Date Jun. 30, 2005. |
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| Claims priority of provisional application 60/528637, filed on Dec. 11, 2003. | ||
| Prior Publication US 2007/0090822 A1, Apr. 26, 2007 | ||
| Int. Cl. H05B 37/02 (2006.01) | ||
| U.S. Cl. 315—291 [315/224; 315/247] | 8 Claims |
| 1. A method for open circuit voltage regulation for an electronic ballast, the method comprising:
providing a resonant tank circuit connected to an output of the electronic ballast;
providing a regulating pulse width modulator having an output voltage threshold limit;
sensing a tank current in the resonant tank circuit to produce a sensed output voltage signal;
comparing the sensed output voltage signal to the output voltage threshold limit; and
limiting the output voltage when the sensed output voltage signal exceeds the output voltage threshold limit by limiting a
pulse width of pulses output from the regulating pulse width modulator.
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