| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable to minimize heat generation of a circuit, reduce the number of wirings, uniformize brightness of light-emitting diodes, and prevent deviation of brightness. <P>SOLUTION: An LED unit 10 has eight LED's 9 all connected in series and the 12 V voltage of a power source 3 by way of a battery of a vehicle is not enough, so that a booster circuit 4 is provided in a control unit 2, by which a boosted voltage of about 16 V is impressed on the eight LED's. The tip of the LED unit 10 is connected to a constant-current circuit 8, in the vicinity of which is a voltage detecting circuit 7 connected to the constant-current circuit 8 for detecting voltage impressed on the constant-current circuit 8, which, compared with a standard voltage 5 taken in from the power source 3, and amplified by an amplifier 6, is inputted to the booster circuit 4 as a booster control signal. The booster control signal is outputted to control the booster current so that voltage detected by the voltage detecting circuit 7 be as low as possible. <P>COPYRIGHT: (C)2003,JPO |
