| 摘要 |
<P>PROBLEM TO BE SOLVED: To reliably detect an abnormality in a semiconductor light source element connected in series, with a simplified circuit configuration. <P>SOLUTION: A semiconductor light source device comprises: LEDs 20A-20D connected in series; a drive circuit 21 driving the LEDs 20A-20D; resistors RpA-RpD connected to the LEDs 20A-20D in series, respectively; a constant current source 22 flowing a prescribed current to the resistors RpA-RpD in non-luminous driving of the LEDs 20A-20D by the drive circuit 21; a voltage monitoring circuit 23 detecting a voltage value applied on the LEDs 20A-20D as a whole while the prescribed current is flown by the constant current source 22; and a control circuit 25 determining the number of elements short-circuited among the LEDs 20A-20D based on a voltage value detected in the voltage monitoring circuit 23 through a level shifter 24. <P>COPYRIGHT: (C)2012,JPO&INPIT |
