| 摘要 |
The apparatus automatically shakes off the eraser for the blackboard to prevent the chalk powder from floating. It comprises a case(10) including an insertion hole(11) for inserting the eraser into, and a drawer(12) for collecting the chalk powder; microswiches(13) serially connected at 4 sides of the hole(11); a speed reducing motor(M) driven by the microswitches(13); a timer(T) driving the motor(M) for a preset time; a rotary plate(14) driven by the motor(M); a twisted spring(17) recovering the position of an impact plate holder(16); an impact plate(20) installed at a side of a hookin member(22).
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