| 摘要 |
PURPOSE:To automatically cut off the power supply to an electronic blackboard even when a power source switch is left turned on so as to economize the power consumption, by providing a photosensor which detects the illuminance of the location where the main body of the backboard is provided and cutting off the power supply when the illuminance detected by the photosensor declines to a level below a fixed value. CONSTITUTION:In an electronic blackboard power supply is required to various members, such as a winding shaft 3 driving motor, etc., and a power supply switch 13 is provided in a power source circuit 12. In addition, a photosensor 14 which detects the illuminance of the location where the main body 1 of this blackboard is provided is installed to the upper front section of the main body 1. Furthermore, a power supply turning-off circuit 16 which turns off the power supply to the blackboard by opening a relay contact 15 connected with the said power supply switch 13 is series when the illuminance detected by the photosensor 14 declines to a level which is lower than a fixed value (for example, 300 x) is provided.
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