| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a light-emitting device in which a plurality of light-emitting elements differing in driving currents are driven by a simple drive circuit and which has high electrical efficiency. <P>SOLUTION: Master light-emitting diodes 7a-7d and a slave light-emitting diode 8a requiring a larger current than the master light-emitting diodes are connected to a main secondary wiring 2b in series, a current detecting resistance 9 detects a main current J2, and voltage detecting resistances 22, 23 detect voltages applied on the light-emitting diodes, and a control circuit 4 controls an opening and closing time rate of a MOSFET 3 to carry out constant current control of the main current J2 in a range within a predetermined voltage, thereby driving the main and slave light-emitting diodes. Furthermore, the slave light-emitting diode 8a is supplied with a slave current L1 which is less than a current needed to obtain a desired light emission output from a slave second winding 2c, and is driven with a salve driving current SJ1. The light-emitting diodes 7 and 8a differing in driving currents are driven by one constant current drive circuit with voltage limitation to simplify the drive circuit and improve efficiency. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
