| 摘要 |
PURPOSE:To maintain a proper light quantity by controlling the cooling quantity with the detection signal of an outer temperature. CONSTITUTION:The blowing quantity of a fan 6 for cooling the rising of the temperature of a tube wall by lighting a fluorescent lamp 3 is changed according to the change of the outer temperature through a control circuit 8 based on the detection signal from a temperature detecting member 7. When the outer temperature is low, the blowing quantity is made minimum because the temperature of blowing wind becomes lower, and when the outer temperature is high, the blowing quantity is move maximum. Thus, the temperature of the tube wall of the fluorescent lamp 3 can be maintained at a proper temperature and the proper light quantity can be obtained whether the outer temperature is high or low. |
