GB726150A - Improvements in or relating to venetian blinds - Google Patents

Abstract

726,150. Venetian blinds. ROLLADENFABRIK A. GRIESSER AKT.-GES. Aug. 19, 1953 [Feb. 21, 1953], No. 22911/53. Class 20 (3). In a Venetian blind of the kind having laths 9 carried by ladder tapes 8 suspended from tilting frames 7 coaxial with and rotatable independently of the winding shaft 2, a lifting drum 13 on the shaft 2 and a lifting tape 12 attached to the lowermost lath, rotation of the tilting frame 7 is brought about by the engagement of one or other-of pawls 21 with a rigidly mounted ratchet wheel 22. When, on turning the shaft 2 to raise or lower the blind a plate 19 integrally attached to the tilting frame 7 reaches either of two positions, a pawl 21 is tripped out of engagement with the ratchet wheel 22 by an abutment 23 and no further tilting can occur. Each of the sleeve portions extending from the sides of frame 7 is squared and carries a disc 14, a flat portion 15 of which rests on a ledge 16 when the laths are in the position shown in Fig. 2. Yokes 18 prevent the shaft from jumping out of its bearings in the plates 17. The blind is operated by a drawtape 4, wound on drum 3, the end of which is attached to a clamping device 25 which consists of a bottomless outer case 26 and a threesided member 27 pivoted at 28, of which the outer end is pressed by spring 29 to clamp tape 4 between it and a rubber strip 31. If the tape 4 is released by pulling member 27 downwards the blind tilts and descends as shown in Fig. 2 under its own weight. If the tape 4 is unwound from the drum 3, the laths tilt in the other direction before the blind begins to rise. When the blind is in motion the upper pawl 21 jumps the ratchet wheel 22. Stops 39 on the frame 17 and 38 may be provided in a modification in which spring pawls 35 in a plate 33 engage holes 37 in a ratchet wheel 36. The first pawl 35 in the direction of rotation is tripped out of engagement by a member 32. An alternative to the discs 14 and ledges 16 comprises a disc with a notch which engages a roller carried on a spring arm. The lower part of the surface 6 to which the ladder tapes 8 are attached by e.g. a spring clamp is apertured extensively for the passage of lifting tape 12, of steel, preferably, or of a synthetic material. Laths 9 are held in bridges 11 fixed to the ladder tapes 8.