| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To radiate light stably, and to prolong the lifetime by reducing stress to an LED. <P>SOLUTION: A driver 5 detects a voltage V3 in a resistor 42 and a voltage V4 in a resistor 43. Then, on the basis of the voltages V3 and V4, DC voltage V1 and DC current I1 of a DC power supply 40 are converted into a drive voltage V2 and a drive current I2 so that electric power consumption, which is the product of the drive voltage V2 and the drive current I2 to be supplied to an LED unit 3 in which a plurality of LEDs 31 are connected in series, becomes constant. Subsequently, the drive voltage V2 and the drive current I2 are supplied to the LED unit 3. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
