| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method of selecting light emitting diodes which reliably discards light emitting diodes having negative resistance characteristics. SOLUTION: A second transistor 6 is set on for a predetermined speed time TR to apply a backward voltage VR to an LED 1, and then a first transistor 5 is set on for a predetermined time Tr to apply a forward voltage to the LED 1. When the forward voltage is applied to the LED 1, a forward current begins to rapidly flow and quickly start the LED 1 to light, if it has a normal p-n junction. But, if the junction structure is abnormal, a time is taken for starting to flow the forward current after applying the forward voltage to the LED 1.</p> |
