BACKGROUND OF THE INVENTION

THIS invention relates to a transmission system for a blind. More specifically, the invention relates to a system for transmitting drive and/or rotation to each of a plurality of slats making up such blind.

Blinds, and specifically blinds made up from rigid slats are well known. An important aspect relating to such blinds is how the slats are movable across a window or doorway opening in a manner that positions the slats equidistantly relative to one another in an expanded condition such that the major sides of adjacent slats can overlap one another when shut.

MOENCH in US patent no. 4,993,469 teaches of a blind transmission system that incorporates a plurality of spacer arms extending between adjacent slat support carriages. The spacer arms are pivotally connected at one end to one of the carriages, and include a hook formation on an opposite end to hook a catch formation on the adjacent carriage, thereby to equidistantly space the carriages in the expanded condition.

As the carriages are brought together into a compact condition (i.e. where the slats are bunched together), an angled surface near the hook formation of each of the spacer arms rides along the catch formation causing the spacer arm to pivot upwardly to allow the carriages to ride nearer and/or into abutment with one another. The MOENCH invention has two clear drawbacks, namely that: (i) with a single drive shaft, the slats of the blind can only be drawn to the compact bunched condition to one side of the window or doorway opening; and (ii) if the spacer arms do not pivot downwardly while the slats are drawn to the expanded condition (i.e. where grit jams up the pivot), the slats will move beyond a position at which their sides will be able to overlay one another in a slat shut condition.

TOTI in US patent no. 2,794,502 also incorporates a plurality of spacer arms extending between adjacent slat support carriages, but instead of being pivotally connected at one end to one of the carriages, they are rigidly fixed spacer arms that are angularly displaceable through inherent material resilience to ride over adjacent spacer arms while drawing the slats to the compact bunched condition. Again, the slats in the TOTI invention can only be drawn to the compact bunched condition to a single side of the window or doorway opening and, once the spacer arms loose their required resilience, the spacer arms will no longer efficiently operate to hook the catch formations on adjacent carriages as the slats are drawn towards the expanded condition.

It is an object of the present invention to provide a transmission system for a blind that not only is capable of equidistantly spacing slats in the shut condition, but also to enable the slats to be drawn together into the open condition at of the ends of the window, or any intermediary position therebetween.

SUMMARY OF THE INVENTION

According to the invention there is provided a transmission system for a blind including: at least first and second threaded drive shafts; a first outer carriage for supporting an end of a first outer slat making up the blind, the first carriage having: a threaded guide for threadably engaging the first drive shaft such that rotary motion of the first drive shaft is transmittable therethrough into an axial sliding motion of the first outer carriage; and an aligning guide sized and shaped for the second threaded drive shaft to pass substantially freely therethrough; a second outer carriage for supporting an end of a second outer slat making up the blind, the second carriage having: a threaded guide for threadably engaging the second drive shaft such that rotary motion of the second drive shaft is transmittable therethrough into an axial sliding motion of the second outer carriage; and an aligning guide sized and shaped for the first threaded drive shaft to pass substantially freely therethrough; and one or more intermediary inner carriages each for supporting an end of a respective inner slat, the intermediary inner carriages each having a pair of aligning guides sized and shaped for one of the first and second threaded drive shafts to pass substantially freely therethrough; wherein drive of the outer carriages is transmittable to the intermediary inner carriages through abutment such that the carriages are axially pushed nearer and/or into contact with one another into a compact condition to either side of a window or doorway opening to which the blind is operably fitted, or any intermediary position therebetween.

Generally, the transmission system includes a plurality of elongate spacers each having a first end, being fixedly connectable to one of the carriages, and a second end, being slidably connectable to the adjacent carriage, wherein the carriages and spacers have respective limiting formations that are operatively abutable with one another to limit the axial displacement of the adjacent carriages relative to one another during operable movement from the compact condition to an expanded condition, wherein the carriages are spaced relative to one another across the window or doorway opening.

Typically, the carriages each comprise one or more primary spacing formations protruding outwardly therefrom, and further wherein the carriage limiting formations are opposing sides of such primary spacing formation. Preferably, the spacers each define at least a socket cavity, sized and shaped for fixedly capturing the primary spacing formation of one of the carriages therein so as to restrict relative axial movement between the spacer and such carriage, and a track cavity, sized and shaped for slidably capturing the primary spacing formation of the adjacent carriage therein, with the ends of the track cavity being the spacer limiting formations, such in the event of abutment between the carriage and the spacer limiting formations during movement of the carriages away from one another, the spacers axially pull the adjacent carriages into the expanded condition.

More preferably, the spacers are near equivalently sized such that the carriages are slidably movable by the spacers near equidistantly apart with respect to one another in the expanded condition.

The carriages may comprise secondary spacing formations protruding therefrom such that a plurality of spacers connected to the same side of the carriage are movable passed each other along separate parallel planes while the carriages are axially driven between the compact and expanded conditions.

Generally, the primary spacing formations are a pair of primary spacing formations extending laterally outwardly from the carriage in a direction facing away from a central axis lying between the first and the second threaded drive shafts.

Typically, the secondary spacing formations are a pair of secondary spacing formations extending laterally outwardly from the carriage in a direction facing away from the central axis lying between the first and the second threaded drive shafts, and operatively superjacent the primary spacing formations.

It will be appreciated that each of the carriages may include further pairs of spacing formations to accommodate a larger number of spacers and their respective movements along planes offset from one another.

The carriages may each comprise a pivot mount for pivotally supporting the end of the respective slat.

Furthermore, the carriages house a gearing cluster therein, and further wherein the geared carriages are interconnected thereby to transmit a rotational motion imparted on one of the slats to synchronised rotational motion of the other slats, such that in use, the slats are rotatable between an open condition, wherein major sides of adjacent slats are spaced relative to one another, and a shut condition, wherein the major sides of adjacent slats overlap one another. Preferably, the carriages supporting one end of the slats are of the type comprising only the pivot mount on which the slats are freely pivotally mounted, while the carriages supporting the opposite end of the slats are the geared carriages. Generally, the geared carriages are interconnected via a connector rod such that rotational motion of the slats is translatable into a rotational motion of the connector rod, such that operable rotation of any one slat or the connector rod causes synchronise rotation of all of the interconnected slats. Typically, the transmission system includes a connector rod drive for driving rotation of the connector rod.

The carriages may ride along elongate tracks on bearings, wheels or bushings. Preferably, the carriages are slidably captive within the elongate tracks.

In a preferred embodiment, the carriages are electrically connectable to the slat to either: (i) electrify the slats in use as an intruder barrier; or (ii) transmit electrical power from photovoltaic slats to power electrical components of the transmission system or other independent system.

Furthermore, the transmission system may include a lock to lock the carriages and/or slats in at least one of the compact, expanded, open and shut conditions.

BRIEF DESCRIPTION OF THE INVENTION

The invention will now be described in more detail, by way of example only, with reference to the accompanying illustrations, in which: Figure 1 is a first perspective view of an embodiment of a transmission system for a blind in accordance with the present invention;

Figure 2 is a zoomed in perspective view of an outer carriage of the transmission system of figure 1 ; Figure 3 is a second perspective view of the transmission system of figure 1 ;

Figure 4 is a perspective view of another embodiment of a transmission system for a blind in accordance with the present invention; and

Figure 5 is a perspective view of a blind assembly incorporating the transmission system of the present inventions.

DETAILED DESCRIPTION OF THE INVENTION

A transmission system for a blind according to a preferred embodiment of the invention is designated generally in figures 1 to 3 by reference numeral 10. The transmission system 10 comprises first and second threaded drive shafts 12, 14, a first outer carriage 16, a second outer carriage 18 and a plurality of intermediary inner carriages 20.

The threaded drive shafts 12, 14 are rotatably supported at their respective ends on a support structure 70, and rotatably driveable by one or more independent drives (not shown). The first outer carriage 16 comprises a pivot mount 22 for supporting an end of first outer slat (not shown) and a threaded guide 24 for threadably engaging the first drive shaft 12 such that rotary motion of the first drive shaft 12 is transmittable therethrough into an axial sliding motion of the first outer carriage 16 in direction“D”.

Furthermore, the first outer carriage 16 comprises an aligning guide 26 sized and shaped for the second threaded drive shaft 14 to pass substantially freely therethrough in a manner that the aligning guide 26 co-operatively with the second threaded drive shaft 14 maintain the first outer carriage 16 substantially square to the threaded drive shafts 12, 14 while moving axially therealong in direction“D”.

Similarly, the second outer carriage 18 comprises a pivot mount 28 for supporting an end of second outer slat (not shown) and a threaded guide 30 for threadably engaging the second drive shaft 14 such that rotary motion of the second drive shaft 14 is transmittable therethrough into an axial sliding motion of the second outer carriage 18 in direction“D”.

The second outer carriage 18 also comprises an aligning guide 32 sized and shaped for the first threaded drive shaft 12 to pass substantially freely therethrough in a manner that the the aligning guide 32 co-operatively with the first threaded drive shaft 12 maintain the second outer carriage 18 substantially square to the threaded drive shafts 12, 14 while moving axially therealong in direction“D”. The intermediary inner carriages 20 each comprise a pivot mount 34 for supporting an end of a respective inner slat (not shown). Furthermore, the intermediary inner carriages 20 each have a pair of opposing aligning guides 36, 38 sized and shaped for one of the first and second threaded drive shafts 12, 14 to respectively pass substantially freely therethrough, in a manner that the the aligning guides 36, 38 co- operatively with the first and second threaded drive shafts 12, 14 maintain the intermediary inner carriages 20 substantially square to the threaded drive shafts 12, 14 while moving axially therealong in direction“D”.

It will be appreciated then, that the intermediary inner carriages 20 are not directly linked to drive via the first and second threaded drive shafts 12, 14. Rather, drive of the outer carriages 16, 18 is transmittable to the intermediary inner carriages 20 through abutment such that the carriages 16, 18, 20 are axially pushed nearer and/or into contact with one another into a compact condition (i.e. condition wherein carriages and slats mounted thereon are bunched together) to either side of a window or doorway opening to which the blind is operably fitted (not shown), or any intermediary position therebetween (i.e. bunched together in the centre of the window or doorway opening).

To drive the carriages 16, 18, 20 into an expanded condition, that is where the carriages are spaced relative to one another across the window or doorway opening, the transmission system 10 includes a plurality of elongate spacers 40, each having opposing first and second ends 42, 44.

The spacer 40, at or near the first end 42 thereof, defines a socket cavity 46 for receiving therein one of a pair of primary spacing formations 60 protruding laterally outwardly from opposing sides of each of the carriages 16, 18, 20, where each of the primary spacing formations 60 comprise opposing carriage limiting formations 62, 64, the use of which will become clearer in the description that follows. The socket cavity 46 is shaped and sized substantially to snugly receive such primary spacing formation 60, thereby to fixedly connect the spacer 40 to the respective carriage 16, 18, 20 so as to restrict relative axial movement therebetween. For the purposes of clearly describing the invention, reference is made to the spacer 40 connectable in figure 1 between the second outer carriage 18 and the adjacent intermediary inner carriage 40, with the socket cavity 46 thereof connected to the second outer carriage 18.

With the socket cavity 46 located at or near the first end 42 of the spacer 40, the remainder of the spacer 40 defines a track cavity 48, extending between the socket cavity 46 and the second end 44 of the spacer 40, for slidably receiving therein one of the primary spacing formations 60 of an adjacent carriage, in this case the immediately adjacent intermediary inner carriage 20. The track cavity 46 is shaped and sized substantially to capture such primary spacing formation 60, while enabling such primary spacing formation 60 to slide therein between spacer limiting formations 50, 52, which are the ends of the track cavity 48.

Wth reference to the second outer carriage 18 and its directly adjacent intermediary inner carriage 20, for the purposes of demonstrating the principle of operation common to all of the carriages, it will be appreciated that the second outer carriage 18 is able to axially displace away from the directly adjacent intermediary inner carriage 20 while its primary spacing formation 60 slides within the track cavity 48 of the spacer 40.

In the event of abutment between the carriage limiting formation 64 with the spacer limiting formation 52, the directly adjacent intermediary inner carriage 20 is pulled axially along with the second outer carriage 18 by the spacer 40, which in turn pulls with it the next adjacent carriage until the carriages arrive in the full expanded condition, preferably spaced equidistantly from one another across the window or doorway opening. To prevent the spacers 40 themselves from coming into axial contact with one another, particular where the transmission system 10 is made up of many intermediary inner carriages 20, each of the carriages 16, 18, 20 preferably comprises a pair of secondary spacing formations 66, much the same as the primary spacing formations 60, protruding laterally outwardly from opposing sides of each of the carriages 16, 18, 20, but positioned thereon superjacent relative to the primary spacing formations 60.

In this manner, the spacer 40 connected between the first outer carriage 16 and its directly adjacent intermediary inner carriage 20 is operative along a plane being operatively parallel and beneath a plane along which the spacer 40 connected between the next intermediary inner carriages 20 is operative. As such, the spacers 40 will be capable of moving passed each other while the carriages 16, 18, 20 are axially driven between the compact and expanded conditions. In a second embodiment of the invention as depicted in figure 4, with like references designating like parts, the transmission system 1 10 comprises first and second threaded drive shafts 1 12, 1 14, a first outer carriage 1 16, a second outer carriage 1 18, a plurality of intermediary inner carriages 120 and a plurality of staggered spacers 140 supported across a support structure 170.

Although the second embodiment of the invention is in essence very similar to the first embodiment depicted in figure 1 and figure 3, the main point of difference is that the carriages 1 16, 1 18, 120 are geared carriages housing therein a gearing cluster 121 for driving slats (not shown) pivotally mounted therein rotatably between respective open and shut conditions.

A connector rod 123 interconnects each of the gearing clusters 121 housed in the carriages 1 16, 1 18, 120 thereby to transmit a rotational motion imparted on one of the slats to synchronised rotational motion of the other slats, such that in use, the slats are rotatable between the open and shut conditions by operable rotation of any one slat or the connector rod, the latter of which could be driven by the drives driving the first and second threaded drive shaft 1 12, 1 14 or an independent drive. In a particularly preferred arrangement as illustrated in figure 5, a blind assembly 200 may be manufactured with the geared carriages 1 16, 1 18, 120 of the second embodiment of the invention (as illustrated in figure 4) supporting the top ends of the slats 210 with the pivot mount carriages 16, 18, 20 of the first embodiment of the invention (as illustrated in figure 1 and figure 3) supporting the bottom ends of the slats, held together within a support structure 70, 170.

Although the invention has been described with reference to a preferred embodiment, it will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention.

For example, the carriages may ride captive along elongate tracks on bearings, wheels or bushings. Another example is that the spacers may instead of clipping to the spacing formations, they could simply be fastened to the carriages with a screw.

Furthermore, the carriages could be electrically connectable to the slats to either: (i) electrify the slats in use as an intruder barrier; or (ii) transmit electrical power from photovoltaic slats to power electrical components of the transmission system or other independent system.

The carriages or slats may also include a lock to lock the carriages and/or slats in at least one of the compact, expanded, open and shut conditions. Also, each of the carriages may include further pairs of spacing formations to accommodate a larger number of spacers and their respective movements along planes offset from one another.