| 摘要 |
PROBLEM TO BE SOLVED: To obtain a specified current regardless of the voltage of inputted power and keep the illuminance of a light emitting element constant, by changing the value of the start resistance of 4 control IC by input voltage, and turning off the control IC, making use of this start resistance for the current limiting resistance of the light emitting element. SOLUTION: When a power save signal is inputted from a host system, a drive circuit 7 stops the output voltage from the tertiary winding 83 of a transformer 8, and besides a reduction circuit 3 leads the current decided by a starting resistor Rs into a light emitting element LED, and starts lighting, and cuts the current of supply power to the control IC 5 so as to stop the operation of the switching power source. Hereby, the illuminance of a power save light emitting element can be kept constant. |
