Friction device for rolling up curtains and the like

A friction device for rolling up curtains and the like, including:

• a tubular roller (1), on which a curtain (1a) is wound;
• support means (10) for rotatably supporting said roller (1);
• a threaded stem (2) supported inside said roller (1) in a way as to create an angular displacement of said roller with respect to said threaded stem during rotation of said roller;
• this device being characterized in that it further includes:
• an operative body (3), situated slidingly inside the roller (1) and screw-fitted onto said stem (2), said operative body (3) being linked to said roller (2) in relation to rotation so as to move axially along said threaded stem (2) during the rotation of the roller due to unrolling and rolling up of said curtain (l a) from a rolled up configuration (A) to be unrolled configuration (B) and vice-versa;
• first elastic means (4) and second elastic means (5) acting on said operating body (3) and in opposition to one another, so as to produce a variable friction effect on said operating body (3)
• during motion of said curtain (la) between said unrolled configuration (B) and rolled up configuration (A), and vice-versa, such that the curtain can be driven in a substantially balanced way during rolling up and/or unrolling;
• first stop means (40) and second stop means (50) fastened to said threaded stem (2), and aimed at pressing respectively and first elastic means (4) and second elastic means (5), against corresponding first surface (3a) and second surface (3b) of said operating body (3).