| 摘要 |
The invention is related to billboards which contain a lower roller (2) and an upper roller (3) that are positioned to perform an axial movement by means of the fixing levers (1.1) on the supporting frame (1 ) and on which the advertisement screen is wound and is characterized by a spring (3.2) which is positioned in the said tube (3.3) of the upper roller (3) and centered and connected by means of a supporting shaft (3.1 ) and a drive group (4) by which movement is transmitted to the said lower roller (2) by using a single drive center to ensure the said advertisement screen to be in a smooth and stretched condition and provide the rollers (2, 3) with movement by using a single drive center. |
