| 摘要 |
PROBLEM TO BE SOLVED: To provide a constant voltage type power source device capable of simply controlling brightness of an LED with good accuracy. SOLUTION: The power source device is composed of a variable voltage power source 3 impressing a voltage corresponding to a received voltage indication signal on the LED 21 and making it emit light; a current measuring part 4 measuring a current flowing through the LED 21 and outputting a measuring signal corresponding to the measured value; a related data generation part 51 changing the value of the voltage indication signal within a prescribed range, generating data indicating the relation between the value of the voltage indication signal and the measured value by obtaining the value of the measuring signal changing in correspondence with the voltage indication signal; and a conversion part 52 receiving light control signals controlling the LED in an intended brightness, setting a value of voltage indication signal corresponding to the value of the light control signal depending on the relation data, and outputting the value of the voltage indication signal to the variable voltage power source. COPYRIGHT: (C)2007,JPO&INPIT |
