| 摘要 |
<p>In a roller blind sign in which the ends of a web (1) of flexible material carrying a pluralty of display items are carried by respective supporting rollers (2, 3), the rollers are mechanically coupled to each other for enabling them to be rotated in unison by a common reversible drive, and the part of the web between the rollers passes over a movable jockey roller (8) which is biased in a direction which ensures that the web is maintained under tension throughout the whole of its transference from one supporting roller to the other, thereby compensating for changes in the length of that part of the web due to changes in the effective diameters of the rollers as the web is transferred.</p> |
