| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of achieving luminous flux-color temperature characteristics allowing color temperature to vary with luminous flux like an incandescent lamp while using LEDs as a light source. <P>SOLUTION: A light source unit 10 has a resistor R2 connected in series to a first LED 11 to prevent the ratio of the luminous flux from the first LED 11 to the luminous flux from a second LED 12 from being constant. Therefore, in the first LED 11, the gradient of a change characteristic of a forward current (voltage-current characteristic) with respect to the variation of an output voltage of a power supply unit 2 is smaller by the amount of the voltage drop occurring in the resistor R2. When the output voltage of the power supply unit 2 is increased gradually, the ratio of the luminous flux from the second LED 12 to the total luminous flux of the emitted light gradually increases. The emitted light is created as a mixed-color light by mixing the output light from the first LED 11 and the output light from the second LED 12. Thus, the color temperature varies with the change of the luminous flux in the emitted light. <P>COPYRIGHT: (C)2012,JPO&INPIT |
