| 摘要 |
PURPOSE:To prevent the quantity of light from decreasing owing to overcooling by controlling a voltage applied to the driving motor for a fan for cooling a light source so that the voltage is high when the quantity of light of the light source is large or low when said quantity is small. CONSTITUTION:A signal generation part 20 sends out a light quantity control signal for a halogen lamp 8 according to the overexposure or underexposure of a film original. This signal is sent to a 1st power source part 17A and a 2nd power source part 17B and when the film original is overexposed, the output voltage is so controlled as to rotate fans 15 and 16 speedily according to the indication of the signal while the light quantity of the halogen lamp 8 is increased. Further, when the film original is underexposed, the output voltage is so controlled as to rotate the fans 15 and 16 slowly while the light quantity of the halogen lamp 8 is lowered. Consequently, even when the light quantity of the light source is lowered and light is projected on the film original for a long time, the light quantity of the light source is prevented from decreasing.
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