| 摘要 |
PURPOSE:To use all the output light for transmitting information while reducing cost by detecting forward voltage of driven LED, controlling thc ambient temperature of an LED drive section or the LED by employing the forward voltage and keeping the power of output light constant. CONSTITUTION:When an LED 1 is driven by an LED drive section 6, an LED output-beam control means 7 controlling the ambient temperature of the LED drive section 6 or the LED 1 by using the forward voltage of the LED 1 detected and keeping the power of output beams from the LED 1 constant is provided. All of LED output beams can be utilized for transmitting information because LED output beams are employed only in an indirect manner in order to stabilize the power of LED output beams while cost is reduced because no expensive spectroscope is used. |
