| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit for lighting system capable of dealing with a wide power supply voltage, without causing deviation of brightness.SOLUTION: A control circuit for lighting system controlling the operation of a semiconductor light-emitting element includes a DC power supply 10 for applying a DC voltage, a current path H with which a light-emitting element 22 is connected in series, a current path I with which a light-receiving element 23, for receiving light outputted from the light-emitting element 22, is connected in series, a current path K with which a semiconductor light-emitting element 26 is connected in series in the same polarity direction, a semiconductor control element 41 connected with the current path K at a position of lower potential than the semiconductor light-emitting element 26 and connected with the light-emitting element 22, and a semiconductor element 25 connected in parallel with the semiconductor light-emitting element 26 at a predetermined interval, and connected with the light-receiving element 23. The semiconductor element 25 is controlled depending on the variation of the DC voltage, and a current flowing through the current path K is controlled.SELECTED DRAWING: Figure 1 |
