| 摘要 |
PROBLEM TO BE SOLVED: To protect a light emitting diode against thermal breakdown due to overload. SOLUTION: An overheat preventive transistor 4 and an overvoltage preventive constant voltage diode 5 are connected in parallel to form a composite protective element 3 which is then connected in parallel with a light emitting diode 2. The transistor 3 is thermally coupled with the light emitting diode 2. When an abnormal temperature is detected utilizing the negative temperature coefficient of the transistor 3, the transistor 3 is conducted to form a bypath of the light emitting diode 2. |
