| 摘要 |
The solution of the drive for the billboard elements having the form of vertical prisms with equilateral triangle section that successively present their walls of which the consists the image, lies in the application, for rotation of each of them, of a set of control plates with a peg and a triangle cam with cut-outs, mounted on the prism axis. The cam is mounted inside the control plate, tangent to its inside edge. The plate performs slow rotational movement and the peg mounted on its edge gets into the cut-outs in the cam edges, rotating it successively by 120 DEG . Simultaneously during the plate rotation, its folded edge 'slides' on the convex cam edge, stabilising its position at the time of presentation of the prism wall. All the plates that co-operate with the cams have common drive or are jointed with cogbelts, V-belts or a chain in order to ensure their simultaneous rotation. Through repositioning of the successive plates by a small angle it is possible to delay the reciprocal cam rotation, which allows for 'waving' change of the image on the advertisement billboard. |
