| 摘要 |
PURPOSE:To eliminate remaining heat by the self-heating of a light source while it is turned on and to obtain a stable emitted light quantity even when the light source is turned on again within a short time by providing an operation means for a cooling means which stops the cooling means after a short time when the light source is turned off. CONSTITUTION:A target temperature decision means 61 decides a target temperature T1 corresponding to an environmental temperature from a temperature sensor 2. Before a fluorescent lamp 4 is turned on, the temperature T1 is maintained by a temperature sensor 1 and a heating means 3. When the fluorescent lamp 4 is turned on, it occurs the self-heating, so that the large part of the temperature T1 can be maintained even in the case of using a cooling fan 5 at the end. The cooling fan 5 makes the rise of the temperature caused by the self-heating small. Besides, it can set the temperature T1 to be low and make the heating capacity of the means 3 small. Simultaneously, when the fluorescent lamp 4 is turned off, the cooling fan 5 is operated for a while by the operating means for the cooling means 63 so that the remaining heat by the self-heating is eliminated and the emitted light quantity when the fluorescent lamp 4 is turned on again is stabilized. |
