| 摘要 |
PURPOSE: A blackboard including a blackboard surface lifting control structure is provided to be used by controlling the position of the blackboard surface of a blackboard and by extending the blackboard surface, wherein a user simply operates the up-and-down lifting of a second board when occasionally required. CONSTITUTION: A blackboard including a blackboard surface lifting control structure includes a frame, a first board, a slider(30), a second board(40), a lifting guide strap(50) and a position setter. The frame has the space for the board arrangement in the inside. The first board is arranged in the space of the inside of the frame in a vertical direction. The slider is connected to both sides of the right and lifts to the position of the frame vertically. The second board has the end parts of both sides connected the slider to be arranged in the inside of the frame and is operated by lifting proportionally to the first board according to the lifting of the slider The lifting guide strap has one end part connected with a slider and the other end connected to the frame to be lifted upwards and downwards for the end parts of both sides of the second board to be guided to be proportionally lifted along the frame. The position setter makes the guide strap to be unwound or wound together with the second board and, at the same time, stops the guide strap for the second board to be fixed on a required position when the lifting operation of the second board is stopped. |
