| 摘要 |
<p>PURPOSE:To preclude an entanglement phenomenon by providing a pantograph mechanism constituted by intersecting a couple of belt plates, which have fulcrums of rotation at the mid-points and are in the same shape, with each other at the fulcrum positions. CONSTITUTION:The couple of belt plates 63a and 63b which have the fulcrums of rotation at the mid-points and are in the same shape are coupled rotatably while made to cross each other at the fulcrum positions. Namely, the angle of intersection of the couple of belt plates 63a and 63b is invariably equal at opposite positions, so when a keyboard cover 41 is placed in opening/closing operation in a right-angled direction in the length direction of long holes 45a and 45b, and 57a and 57b connecting two places of the front ends of the couple of belt plates and the two places of the rear ends, the movement quantity becomes equal between both end parts of the keyboard cover 41. Therefore, even when one of both end parts of the keyboard cover is held in the hand and opened or closed quickly, the keyboard cover never slants. Consequently, the entanglement phenomenon is precluded.</p> |
