| 摘要 |
PROBLEM TO BE SOLVED: To prevent light from a built-in light source from being leaked from an exhaust port to the outside of a casing without reducing the exhaust efficiency of an exhaust fan. SOLUTION: The position of a light shielding plate is arranged on a position corresponding to the gap of the exhaust fan 1 by controlling a light shielding plate power supply part for the power supply of a motor (stepping motor) for the light shielding plate 2, the phase of a power supply pulse from a fan power supply part for the motor of the exhaust fan 1 is matched with that of a power supply pulse from the light shielding plate power supply part for the motor of the plate 2 to synchronize the two motors and rotate the discharge fan 1 and the plate 2 in the same positional relation. Since light from the built-in power supply is shielded by either one of the exhaust fan 1 and the plate 2, the light is not leaked from the exhaust port to the outside and exhaust air is smoothly discharged from the exhaust port. |
