Cordless balanced window covering

#1. Field of the Invention

#The present invention relates generally to the art of spring motors useful for a variety of applications, including venetian blinds and window shades. More specifically the present invention relates to a system in which lifting cords and cord mechanisms are eliminated from shades or blinds. More specifically the invention relates to window covering systems which, inter alia, employ one or more spring motors to balance the weight of the accumulated window covering material, independent of the extent to which the blind or shade is raised or lowered. Even more specifically, the present invention utilizes an adjustable friction member for engagement with one of a coupled drive and drive actuator to permit the use of spring motors not requiring such rigid specifications.

#2. Description of the Art

#FIG. 1 is a schematic front elevational view, partially in fragment to illustrate the placement of a spring motor for operation in a venetian blind;

#FIG. 2 is an enlarged fragmentary plan view of the motor shown in FIG. 1;

#FIG. 3 is an enlarged perspective view of an adjustable friction member which is engageable in the spring motor to permit adjustment of the friction so as to allow the motor to be employed with various venetian blind and/or shade systems;

#Referring now to the drawings, it is understood that the drawings are intended for illustration of the preferred embodiments of the invention and not for the purposes of limiting the invention. As illustrated, FIG. 1 schematically portrays a motor 10 operatively associated with a venetian blind unit 12 to provide a cordless arrangement for elevating and lowering the blind. As illustrated, the venetian blind unit 12 includes a headrail 14, a bottom or bottom rail 16, and a plurality of slats 18. As is known in the art, the slats 18 are independently supported from the headrail 14 as by flexible members or cords 20, 22 so as to be vertically spaced from one another when the bottom rail 16 is lowered, as shown in FIG. 1. The bottom rail 16 is connected to the terminal ends 20a, 20b of the cords 20, 22. When the bottom rail is elevated, the slats collectively stack upon one another and are supported by the bottom rail 16 when the latter is elevated to its retracted position beneath and closely adjacent the headrail 14. Motor 10 may be mounted in the headrail by any convenient means.

#Referring now to FIG. 2, the motor 10 comprises a storage drum 30 having a first axis 30a and an output drum 40 mounted for rotation about a second axis 40a parallel to and spaced from the first axis 30a. A spring member 35 is connected to and between the storage drum 30 and the output drum 40 to form a spring motor 11. As illustrated, the spring motor 11 has or includes laterally extending, spaced apart drum supports or side walls 50, 52 on opposite sides of the drums 30 and 40 to support them for rotation therebetween. In the position shown in FIG. 2, the spring 35 is tightly wound on the storage drum 30 (and this corresponds to a condition where, as will be shown hereinafter, the bottom rail 16 lies closely adjacent the top rail 14 supporting the slats 18 on the bottom rail). A coupled drive 60, in the present instance comprising a plurality of gears 62, 64, 66, and 68, have the gears 64 and 66 connected respectively to the storage drum 30 and the output drum 40 of the spring motor 11. The coupling of the drive by the gears forces rotation of one of the drums 30, 40 in a first direction about its axis and the other of the drums in an opposite direction allowing winding and unwinding of the spring member 35 between the drums.

#The coupled drive actuator comprises flexible member or cord storage spools 70 and 72, and are connected to the gears 62 and 68 respectively while being mounted for rotation by axles 71 and 73 of the spools 70 and 72. As shown, the flexible member or cord 22 is wound upon spool 72 while the flexible cord 20 is wound on the spool 70. Because the gears 62 and 68 form part of the coupled drive or drive train 60, it is easy to ascertain that if the cord 22 (relative to FIG. 2) is moving to the right, in the direction of arrow 21, then the cord 20 must be moving to the left in the direction of the arrow 19. This corresponds to a lowering of the blind. Again because of the coupled drive and coupled drive actuator 60, as the flexible member or cord 22 is pulled to the right, the spring member 35 starts winding on the output drum 40 and unwinding from the storage drum 30.