| US 7,402,960 B2 | ||
| LED-based lamp apparatus | ||
| Yuji Kajita, Chita-gun (Japan) | ||
| Assigned to DENSO Corporation, Kariya (Japan) | ||
| Filed on Jan. 09, 2007, as Appl. No. 11/651,131. | ||
| Claims priority of application No. 2006-004345 (JP), filed on Jan. 12, 2006. | ||
| Prior Publication US 2007/0159736 A1, Jul. 12, 2007 | ||
| Int. Cl. H05B 37/02 (2006.01) | ||
| U.S. Cl. 315—291 [315/224; 315/225; 315/127; 315/312; 323/276; 323/278; 323/271; 363/80; 363/74] | 4 Claims |
| 1. A lamp apparatus comprising:
a LED unit including a plurality of light emitting diodes connected in series;
a circuit including a switching element and for stepping up a power supply voltage by a switching action of the switching
element to supply an electric current to the LED unit;
a sensing element for measuring a value of the current; and
a controlling element connected in series with the LED unit to control the current based on the measured current value.
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