| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent that a reverse voltage more than a rated forward voltage is applied to each semiconductor light-emitting device without using additional electric components, such as a reverse voltage preventing diode and the like, when using a constant voltage power source which has an output voltage more than the reverse voltage of the semiconductor light-emitting device to supply a constant current to the semiconductor light-emitting device driven by a current. <P>SOLUTION: A voltage output from a constant voltage power source 106 is dropped to a voltage at a midpoint between a resistance R1 and a resistance R2 by a current flowing in the resistance R1 (and the resistance R2). Since this voltage is a forward voltage of an LED2, a reverse voltage applied to an LED4 does not exceed a rated forward voltage, either. An output voltage of the constant voltage power source 106 is set to more than the reverse voltage of the LED to maintain a constant current. When switching transistors Q1 and Q2 are shared, application of the reverse voltage more than the rated forward voltage between two or more basic lighting control circuits which are correlating with each other can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
