The invention relates to a device for pairwise coupling of rotatable shafts of systems for window covering.

Rotatable shafts of adjacently placed systems for window covering are in practice mutually coupled with the purpose of enabling simultaneous operation thereof by means of a control which preferably takes a motorized form. One motor then suffices to drive the shafts of the coupled systems, whereby the cost of a second motor can be saved. It is of great importance here that the adjacent window coverings are aligned, i.e. that the bottom slats of the adjacent window coverings hang at the same height. For this purpose the window coverings must be made extremely accurately to size for assembly purposes. Even then it is found unavoidable in practice that a difference results in the height of the slats of adjacent window coverings. Even a difference of only a few millimetres is visible to the naked eye and is perceived as irritating.

The invention has for its object to provide a device for pairwise coupling of systems for window covering, which are each provided with at least one rotatable shaβ4or-windir4g-up-c^nwinctag4he4fvindow-cαveri^ adapted for connection to the winding shaft of a first system, a second part adapted for connection to the winding shaft of a second system, wherein the first and second parts are rotatable relative to each other and wherein the first part and the second part are provided with co-acting adjusting means which are adapted to adjust the winding shaft of the second system relative to the winding shaft of the first system over a desired angle of adjustment and to fix the winding shaft of the second system in the corresponding position.

Owing to the adjusting means the two parts of the device according to the invention can be adjusted relative to each other such that the corresponding winding shafts, and thereby the window coverings mounted thereon, come to hang at the same height.

Such a coupling device is known from European patent application EP 1936107. The known coupling device is provided with co-acting adjusting means with mutually engaging teeth. During each rotational adjustment of the winding shafts the teeth must first be moved apart in axial direction. The known coupling device is provided for this purpose with an additional telescopic end plug. As a result of the mutually engaging teeth only a stepwise adjustment is possible. The present invention has for its object to provide a coupling device of the type stated in the preamble, which enables a continuously variable, infinite adjustment with a minimum number of parts.

For this purpose the coupling device according to the invention has the feature that the adjusting means comprise a worm wheel transmission, wherein the worm screw forms part of the first part and the worm wheel forms part of the second part.

The coupling device according to the invention provides with few parts a continuous, endless adjustment which can moreover be operated in simple manner. The practical problems outlined above are hereby obviated.

By applying a worm wheel transmission the production costs of the device according to the invention can remain low. This stems from the lower cost of the worm wheel transmission itself and from the fact that a worm wheel transmission is self-braking, whereby the use of a separate brake has become unnecessary. In addition, a worm wheel transmission is technically very reliable.

In a first preferred embodiment of the device according to the invention the first part comprises a peripheral edge in which the worm screw is received. The worm screw is readily accessible in the peripheral edge so that the adjustment can be performed on location in the position of use of the coupling device. According to a further development, the peripheral edge is further provided with an adjusting screw for adjusting the worm screw. Together with the adjusting screw, the worm screw forms a stable two-part structure.

In a further development the worm wheel is enclosed by the peripheral edge. The worm wheel transmission is hereby fully concealed in the peripheral edge. The width of the peripheral edge now defines the built-in dimension. By choosing the narrowest possible peripheral edge the light gap between adjacent systems for window covering can remain minimal.

According to an elegant preferred embodiment of the device according to the invention, the first part comprises a central bush for receiving an outer end of the winding shaft of the first system such that the first part can co-rotate with the winding shaft.

According to a further development, the second part is provided with a central passage for the bush such that the second part is rotatable round the bush.

In a practical preferred embodiment the worm wheel is arranged round the passage.

According to a practical preferred embodiment, the second part is adapted for clamping connection to the winding shaft of the second system. The invention also relates to an assembly of a first system for window covering and a second system for window covering, which are each provided with at least one rotatable shaft for winding up or unwinding the window covering, wherein the first system is provided with a control for rotatingly driving the winding shaft, wherein the assembly is further provided with a device according to the invention, with which the first and the second system are coupled in pairwise manner. In a preferred embodiment the control comprises a motorized drive.

The invention will now be described in more detail with reference to the figures.

Figure 1 shows an assembly of two systems for window covering which are coupled by means of a device according to the invention.

Figures 2 and 3 shows an exploded view of the assembly of figure 1.

Figures 4A and 4B show two schematic views of the device according to the invention.

Figure 5 shows an exploded view of the device according to the invention.

Like components are designated in the figures with like reference numerals.

Figure 1 shows an assembly 50 consisting of a first system 30 for window covering and a second system 40 for window covering. Systems 30 and 40 are each provided with at least one rotatable shaft 31, 41 for winding up or unwinding the window covering. Assembly 50 can be mounted on a wall or a ceiling by means of mounting means 51.

For the sake of clarity the type of window covering is not shown here. The invention will be described with reference to the figures in the context of application in roller blind systems, it will however be apparent that the coupling according to the present invention is suitable for all window coverings which can be wound up and unwound. Several examples of such window coverings are horizontal blinds, folding blinds and pleated systems with raising cords. Figure 2 shows an exploded view of assembly 50, as does figure 3. It can be seen here that the first and second system are mutually coupled by means of a device 1 according to the invention.

Figures 4A and 4B show device 1 in two schematic views, while figure 5 shows an exploded view of device 1. Device 1 consists of a first part 10 and a second part 20. First part 10 is adapted for connection to winding shaft 31 of first system 30, while second part 20 is adapted for connection to winding shaft 41 of second system 40. First part 10 and second part 20 are rotatable relative to each other.

It is noted for the sake of completeness that the term winding shaft can here be understood to mean a roller blind tube. In other systems, for instance with raising cords, winding shaft can be understood within the scope of the invention to mean a rotatable shaft provided with a winding roller.

First part 10 is provided with a bush 12 with an opening 14 for receiving an outer end 32 of winding shaft 31. The periphery of opening 14 and/or outer end 32 of winding shaft 31 is non-round such that first part 10 co-rotates with winding shaft 31.

Second part 20 is provided with a passage 22 in which bush 12 can be received. The dimensions of passage 22 and bush 12 are chosen such that second part 20 is freely rotatable round first part 10. Second part 20 is adapted for clamping connection to winding shaft 41 of second system 40. In the illustrated example of roller blind tubes the clamping connection is formed by wedge-shaped elements 24 arranged around the outer periphery of second part 20. Roller blind tube 41 is hollow and the inner dimensions are chosen such that part 20 with wedge-shaped elements 24 can be clampingly received herein.

Second part 20 is further provided with a peripheral edge 23 which, in the assembled situation of the first and second parts, ties against peripheral edge 13 of first part 10. Adjusting means are received in peripheral edge 13 for adjusting the position of second part 20 relative to first part 10. Since second part 20 is fixedly connected to winding shaft 41 and first part 10 is fixedly connected to winding shaft 31 , this automatically results in an adjustment of winding shaft 41 of second system 40 relative to winding shaft 31 of first system 30 over a desired angle of adjustment V.

The adjusting means comprise a brakable tooth wheel assembly which is preferably formed by a worm wheel transmission. The worm wheel transmission consists of a worm 11 , which is formed by a shaft with screw thread and is also referred to as a worm screw, and a worm wheel 21 with spiral-shaped, oblique teeth. The axes of worm 11 and worm wheel 21 lie crosswise relative to each other. The worm forms the drive part, the worm wheel the driven part.

In the shown preferred embodiment 1 worm wheel 21 is situated on second part 20 and worm screw 11 is situated on first part 10. Worm screw 11 is adjustable by means of an adjusting screw 15 and an

Allen key 16. Adjusting screw 15 extends partially into worm screw 11 and is bearing mounted therein. Together they form a stable two-part structure. Because use is made of a brakable tooth wheel assembly, in this case a worm wheel transmission, adjusting means 11, 21, 15 also have a fixing function.

After rotation of second part 20 through the desired angle of adjustment V, winding shaft 41 will automatically remain in the corresponding position. Several examples of alternative brakable tooth wheel assemblies are a tooth wheel assembly with a high transmission or a tooth wheel assembly with brake. The coupling device according to the invention is easily accessible and simple to operate. The first part herein forms the reference point (fixed world) relative to which the second part is rotatable. The invention is of course not limited to the described and shown preferred embodiment. By applying a plurality of devices according to the invention the number of systems for coupling can for instance be increased as desired.

The invention therefore extends to any embodiment falling within the scope of protection as defined in the claims and as seen in the light of the foregoing description and accompanying drawings.