| 摘要 |
An electromotive blackboard eraser is provided to wipe off the surface of a blackboard clearly by using a pair of chalk shaking rods and to collect chalk dust generated in automatically shaking the chalk shaking rods. An electromotive blackboard eraser is composed of: a case(100) vertically installed at a blackboard, wherein the lateral side of the case coming into contact with the blackboard is opened; a pair of chalk shaking rods(200) rotatably installed in the case; a dust collecting duct(300) installed in the center of the case to communicate with the inside of the case; a driving unit(400) rotating a pair of chalk shaking rods; an outer body covering the driving unit; and a transfer unit(500) horizontally moving the rotating chalk shaking rods. The driving unit comprises a first gear(420) turned by driving of a motor(410) and a second gear(430) engaged with the first gear and provided with rotational speed ratio different from that of the first gear. The chalk shaking rods connected to driving shafts(421,431) of the first and second gears have different rotational speed ratios.
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