| 摘要 |
PURPOSE: An automatic lifting blackboard is provided to lift the blackboard smoothly and silently, reduce manufacture cost due to easy manufacture and installation and improve the efficiency of study. CONSTITUTION: A metal plate(21) of magnetic material(29) is mounted on the rear of the blackboard(11) in a vertical direction. A roller is rotatably mounted in contact with the metal plate(21) and contains a magnet(28). A motor(24) normally rotates and reversely rotates the roller for vertically moving the metal plate(21) and the blackboard(11).
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