| 摘要 |
FIELD: mechanics. ^ SUBSTANCE: device consists at least of two drums parallel to each other, band of placards wound on drums, motor and fixed support device. Placard band includes the front surface visible for people and rear surface. Support device gives a certain shape to rear surface of placard band between drums. Support device includes air chamber and air injection device. Air chamber is restricted with peripheral support frame adjacent to rear surface of placard band and with bottom part. The latter is offset backwards in relation to support frame. Inside support frame, the support device does not have any elements located near rear surface of placard band. Air injection device creates excess air pressure in air chamber for forming a thin air gap at boundary line between support frame and rear surface of placard band. ^ EFFECT: invention allows eliminating friction of and damage to placard band when it is scrolled along support device, and dirt of placards. ^ 10 cl, 5 dwg |
