In view of the existing manual blackboard noise, poor perspective, dust hazards and other shortcomings, it designs a wheel conversion bit blackboard. The three blackboards are fixedly connected with the pins on the chain, and the power is provided by the motors. It realizes the circular motion of the three blackboards along the fixed track. It uses the motors and chain drive to control three blackboards, connects the pin on the chain with each blackboard, achieves three of the blackboard along the fixed trajectory cycle movement. The blackboard is automatically erased by extruding and rubbing ...
