AN IMPROVED LOUVRE SYSTEM

FIELD OF THE INVENTION

The present invention relates to an improved louvre system. The invention may find particular use in domestic applications such as louvres for houses. However, the invention may also be used in a wide range of other applications.

BACKGROUND

Louvres are commonly used in windows, and they are also often used to create other forms of shades, coverings, screens and the like. Louvres typically comprise a number of long thin blades each of which is pivotably mounted to rotate about an axis parallel to the length of the blade. The blades are mounted adjacent each other so that pivoting the blades causes variable opening and closing of the window or covering.

The ends of the louvre blades are generally connected to a side frame in a manner that allows this pivotal movement.

Figure 1 shows an example of the way louvres can be used to create windows. In Figure 1, the louvre blades comprise long thin rectangular panes of clear glass. However, other materials can also be used to create other forms of windows. Figures 2 and 3 illustrate other ways that louvres can be used to create other forms of coverings and shades. In Figure 2, the louvres create a variably openable and closable shade for each of the windows of the house (the windows are scarcely visible in Figure 2 because they are behind the partially closed louvres). Similarly, in Figure 3 the louvres create a variably openable and closable screen for the side of a verandah.

hi Figures 1-3 (and in louvres systems generally), the blades usually pivot in concert with each other. In other words, the respective blades remain at least substantially parallel to each other as they rotate, meaning that the angle of rotation of every blade in the louvre assembly is substantially the same. This allows the louvres to be closed by pivoting the blades so that the long edge(s) of each blade partially overlaps with the long edge(s) of the adjacent blade(s) to prevent clear lines of sight between the blades. Closing the louvres in this way can variously prevent light, wind, water etc from penetrating between the blades. Conversely, the louvres can be opened by pivoting the blades to open up clear sight-lines between the respective adjacent

blades. The extent to which the louvres are "open" depends on how far the louvres are rotated and thus how wide the sight-line between the blades becomes. The wider the sight-line between the blades, the more open the louvres may be said to be.

The person skilled in the art will appreciate that louvre blades can generally pivot between two extremes. At one extreme, each blade is oriented so that its edge(s) overlap with the edges(s) of the adjacent blade(s). Then, as the blades are rotated away from this extreme, the sight-lines between the blades begin to open until the sight-lines reach their maximum width whereupon the louvres are fully open. Further rotation of the blades in the same direction will then cause the sight-lines between the blades to reduce in width until the blades' edges again overlap closing the sight-lines and thus closing the louvres at the other extreme. In most louvre systems, the extent of the blades' rotation between the two extremes is generally slightly less than 180° (typically approximately 170°), because the overlap and contact between the blades at each extreme prevents the blades from rotating a full 180°.

It will be appreciated that the arrangements shown in Figures 1-3 are given for the purpose of example only, and that louvres can be used to create a wide range of other forms of windows, screens, coverings, shades and the like. For example, in some instances louvres may be used to create screens in which the length of the blades extends vertically and the blades pivot about vertical axes.

There are a number of problems associated with louvre systems currently available in the marketplace. One problem arises from the fact that many existing louvre systems require the louvres to be fully assembled offsite prior to installation on the house or building. In other words, in these systems the louvre blades must be assembled and mounted within the louvre frame and the entire louvre assembly must then be installed on the house or building, effectively as one piece. In these instances, the size and weight of the assembled louvres can make the job of installation heavy and difficult work, often requiring two or more workmen. This can in turn increase the time and cost of louvre installation.

Other existing louvre systems allow the blades to be inserted after the frame has been installed. However, in most of these systems, the louvre blades typically need to be

carefully slid into or positioned in cradles or other fittings that are already mounted to the sides of the frame to receive the ends of the blades. Inserting the blades into these receiving fittings can be a fiddly, difficult and time-consuming exercise, and great care must often be taken not to damage the blades while inserting them into the fittings. Removing the louvre blades in these arrangements can also be problematic, and indeed in some arrangements it is necessary to remove many or all of the blades simply to replace a single blade (for example a single broken blade).

Louvre systems generally require some kind of actuator to enable the user to selectively adjust the angle of the louvre blades, hi many existing arrangements, the actuator comprises a lever or levers extending out of one or both sides of the frame.

The lever(s) can be rotated in an arc (as shown for example by the arrows in Figure 1) to adjust the angle of the blades. The lever(s) generally operate a mechanism extending inside the length of the frame which functionally connects the lever(s) to each of the blades so that the rotation of the lever(s) is imparted to each of the blades.

This lever arrangement and the associated mechanism has a number of problems. One particular problem arises when the louvres are to be used to create shades or other coverings mounted on the outside of buildings, but where it is desired for the louvres to be operable from the inside of the building. Figure 2 provides one example of such a situation. In Figure 2, the louvres are mounted on the outside of the house to provide shade to the windows, but it would be preferable if the louvres could be adjusted from inside the house so that it is not necessary for the user to go outside to adjust the louvres. With the lever arrangements described above and shown for example in Figure 1, operation of the external louvres from inside the building can create significant difficulties.

Attempts have been made to overcome this problem using a gearbox type arrangement. In these arrangements, a rotatable "winder" type handle is mounted on the inside of the house or building for operating the louvres. A shaft is then provided which extends through the building's exterior wall connecting the handle to a gearbox associated with the blade operating mechanism in the louvre frame. Hence, in these arrangements, the rotation caused by winding the handle from inside the building is transmitted to the gearbox via the connecting shaft, and the gearbox then imparts the

rotation to the blade operating mechanism to change the angle of the blades as desired.

These gearbox arrangements have overcome a number of the difficulties associated with operating exterior louvres from inside a house or building, and from locations remote from the louvres. However, the gearbox arrangements have also given rise to additional problems. In particular, with these gearbox arrangements it is possible to

"force" the louvre operating mechanism by attempting to continue winding the handle, even after the louvre blades have reached the closed position at one or other of their extremes of rotation. Such attempts to "force" the mechanism by over-winding the handle can result in damage to the gearbox and/or other internal components of the louvre operating mechanism.

Yet a further difficulty with existing louvre arrangements arises because the mechanism which transmits the rotation from the lever or the gearbox to the blades is contained within the frame. This is a problem particularly in instances where damage occurs to the internal mechanism or components thereof, or where it is necessary to perform maintenance or adjustment of the mechanism. Because the mechanism is contained within the frame, it can be necessary to significantly disassemble the louvre assembly (for example by removing some or all of the blades at least) in order to perform the repairs or maintenance. This is so even if the mechanism is only affected in its operation in respect of, say, one of the blades.

It will be clearly appreciated that any reference herein to background material or a prior publication is for the purpose of assisting in understanding the invention only and is not to be taken as an acknowledgement or admission that any background material, publication or combination thereof formed part of the common general knowledge in the field, or is otherwise admissible prior art, whether in Australia or in any other country.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a louvre system which may at least partially ameliorate one or more of the above-mentioned disadvantages, or which may provide a useful or commercial choice in the marketplace.

In a first aspect, the present invention resides in a louvre system comprising a frame, one or more blades, resilient means for connecting at least one blade to the frame, an actuator for selectively changing the angle of the one or more blades relative to the frame, and anti-forcing means. Suitably, resilient means may be used for connecting many or all of the blades to the frame. Also, the actuator may be associated with a louvre actuating mechanism.

Thus, the invention in accordance with the first aspect may help to overcome a number of the disadvantages mentioned above. For example, the resilient means which are adapted for connecting blade(s) to the frame may help to significantly reduce the difficulty in inserting the blades into the frame, including where the blade(s) are inserted into the frame after the frame has been installed on site. The resilient means may also reduce the difficulty in removing the blades (even individual blades) from the frame. Allowing simpler installation and removal of the blades may also help to reduce the time (and hence the cost) of louvre installation, maintenance and repair, and it may also help to reduce the incidence or likelihood of damage to louvre blades as they are installed in, or removed from, the frame. Furthermore, the anti-forcing means may prevent or at least reduce the possibility of causing damage to components of the louvre system by forcing the actuator.

The frame used in the present louvre system may be made from any material known by those skilled in the art to be suitable, and it may take any suitable configuration. It is envisaged that the frame will typically comprise at least a first side and a second side with the respective ends of each of the blades connecting with the respective sides of the frame. In most cases, the two sides of the frame will be oriented substantially vertically with the louvres extending substantially horizontally between the two sides. However, no limitation is meant thereby and other configurations are also possible. For example, the two sides may be oriented substantially horizontally with the blades extending vertically therebetween, or the sides may even be oriented diagonally with the blades extending diagonally therebetween. It is also possible that the blades may extend at an angle other than perpendicular relative to one or both of the sides.

Preferably, the resilient means for connecting the blades(s) to the frame may be associated with one or more of the blades. The frame may then incorporate apertures, indents, detents, holes or any other formations or features capable of receiving the resilient means that connect the blade(s) to the frame. In embodiments where the frame has two sides, one or both of the sides may have these formations or features. The configuration of the sides will also preferably provide structural rigidity to the louvre system. Hence, the sides may comprise structural members such as box sections or the like, and each side may be formed as a single unitary component or from multiple components, m particularly preferred embodiments, the frame may be adapted to receive a gearbox (described further below). The frame may also comprise other parts, such as a top and bottom etc.

The blades used in the present louvre system may take a wide range of forms. For example, when the louvre system is used to create a window, the blades will often (but need not necessarily) comprise panes of glass similar to those described in the background section above. In other applications such as shades and screens, the blades may be made from other transparent, translucent or opaque materials such as plastics, metal, wood etc depending on the particular needs of the intended application. As an example of this, where the louvre system is used to create a shade, the blades may be substantially opaque to block out light when the louvres are closed and to reduce the amount of light coming in when the louvres are partially closed. The blades may take any suitable shape (including planar and non-planar shapes), although it is envisaged that the blades will normally have a long thin substantially rectangular shape. Those skilled in the art will appreciate that the material from which the blades are made should be sufficiently rigid to enable the blades to function in the louvre assembly, and the blades will preferably also be resistant to damage from exposure to the environment to which they may be exposed in their particular applications. Hence, in different applications, the materials from which the blades are made may be able to variously withstand things like wind loading, exposure to ultra violet radiation, rain and moisture exposure, extremes of temperature etc.

As explained above, in the first aspect of the invention, at least one blade (but preferably some or all of the blades) in the louvre system has resilient means adapted for connecting each said blade to the frame. The resilient means may be on one or

both ends of the blade. Suitably, the resilient means may include features adapted to engage with the corresponding features on the frame to enable the blade to be mounted to the frame in a pivotable manner. Suitably, the feature(s) on at least one end of the blade will be resilient to enable easy installation of the blade. The resilient means for connecting the blade to the frame may be part of the main body of the blade, or a separate component that can be attached to the main body of the blade before the blade is installed in the frame.

The resiliency of the resilient means may be achieved in a number of ways. For example, the feature(s) on the blade which engage with the corresponding features on the frame may be flexible or bendable. Alternatively, in preferred embodiments, the resilient means may comprise a feature or features which can be depressed as the blade is inserted into the frame, and which can then snap back into position once the blade is correctly oriented within the frame. Hence, preferred embodiments of the resilient means may provide a "snap fit" type arrangement.

In particularly preferred embodiments, end caps may be provided which can be attached on an end of the main body of each blade before the said blade is inserted into the frame. Preferably, a pair of end caps may be provided which can be attached on the respective ends of each blade. Each end cap may include a short rod, pin or stub axel type member (hereinafter referred to as a "rod") extending outwardly away from the respective end of the blade, the rod being adapted to be received in a corresponding hole or similar feature in the frame so as to enable that end of the blade to be secured to the corresponding side of the frame in a pivotable manner. Suitably, the rod of the end cap on at least one end of the blade (i.e. the rod on one end of the blade) may be resiliently inwardly depressible, although the depressible rod in each case should also be biased towards an extended non-depressed position. Put another way, the rod on at least one of the end caps on each blade may be displaceable against its bias (in the direction of the rod's longitudinal axis) into the end cap and towards the main body part of the blade.

m embodiments that operate with the pair of end caps described above, each blade may be installed in the frame by first inserting the rod on one end of the blade (i.e. the rod on one end cap) into its corresponding receiving hole or other feature on one side

of the frame. Then, in order to position the rod on the other end of the blade in its corresponding receiving feature the other side of the frame, the rod on that second end may be depressed out of the way so that that rod does not impact with, or slides across, the frame as the blade is manipulated into position. Finally, when the blade is correctly positioned, the rod on the second end may be released whereupon it may snap back out into engagement with its receiving feature in the frame, thereby securing the second end of the blade to the frame. Individual blades may be removed from the louvre assembly simply by reversing this process.

The louvre system in accordance with the first aspect of the invention has an actuator to enable a user to selectively change the angle of the blades relative to the frame. It is envisaged that the actuator will typically comprise a winding handle similar to those used in some existing louvre systems and described in the background section above. However, no particular limitation is meant in this regard and any other form of actuator known by those skilled in the art to be suitable for allowing operation of a louvre system may be employed. For example, automatic or electronic mechanisms having internal electric winder motors etc.

The actuator may be associated with a louvre blade actuating mechanism so that operation of the actuator causes the angle of the louvre blades to change as desired.

This mechanism may take any suitable form. However, in preferred embodiments, the mechanism may incorporate a gearbox, preferably located in, or associated with, the frame. In embodiments having a gearbox, the actuator should be of a type which can be operated to deliver rotation, such as for example a winding handle or an electric winder, which can deliver many revolutions of rotation. This rotation may be transmitted to the gearbox. In some cases, the actuator may connect directly to the gearbox so that the rotation of the actuator is delivered directly into the gearbox.

However, in other cases (for example where the actuator is inside a building and the louvres, including the gearbox, are on the outside) the rotation of the actuator may be transmitted to the gearbox by any suitable arrangement of shafts, linkages, chains, belts, gears and the like. In any event, the gearbox may then further transmit the rotation to the louvre blades.

In particularly preferred embodiments, a louvre blade actuating mechanism may operate to directly alter the angle of rotation of only one of the blades (hereinafter referred to as the "driven" blade). The angle of rotation of any other blades in the louvre assembly (the "slave" blade(s)) may be associated with the rotation of the driven blade by linking means. Suitably, the linking means may connect the driven blade to each of the slave blades in such a way that rotation of the driven blade (by operation of the actuator and gearbox etc) is transmitted to each of the slave blades. Hence, the linking means may cause the slave blades to rotate in concert with the driven blade, enabling the louvre system to operate in the normal manner. Preferably, the linking means may comprise an elongate rigid member (hereinafter referred to as a "control bar") attached via pivotable connections to each respective blade in the louvre assembly. Suitably, the connection between the control bar and each of the blades in the louvre assembly may be such that the control bar is outside the frame and easily accessible.

The control bar may incorporate means for preventing itself from rotating significantly about an axis parallel to its length. Such rotation of the control bar might cause flexing and strain on the connections between the control bar and the blades. Preferably, the control bar may incorporate features such as wings, edges, protrusions or the like which may contact with the blades, the frame, or both to prevent the above- mentioned rotation related flexing and strain.

As described above, in embodiments that use a control bar, the control bar will preferably be attached via pivotable connections to each respective blade in the louvre assembly. This pivotable connection between the control bar and each respective blade may also be easily disconnectable. This may enable the control bar to be temporarily disconnected from individual blades. When it is also considered that the resilient means for connecting the blades to the frame allows easy removal of individual blades as described above, those skilled in the art will appreciate that this control bar type configuration may be considerably simpler to maintain and repair than the mechanisms in many existing louvre systems. For example, unlike the existing systems described above where the mechanism for changing the angle of the blades is contained within the frame, in preferred embodiments of the present invention, the control bar may be positioned outside the frame and may therefore be

easily accessible for repair or maintenance. Furthermore, because the control bar may be easily disconnectable from individual blades, and because the resilient means allow individual blades to be easily removed, the present system may facilitate maintenance or repair of the mechanism, or replacement of individual blades, without the need to substantially disassemble the entire assembly.

The first aspect of the present invention also includes anti-forcing means. Suitably, the anti-forcing means may prevent forcing of the louvre blade actuating mechanism in cases where the user attempts to operate the actuator to try and force the blades to rotate beyond one of the extremes of rotation. As the blades cannot rotate past either of the extremes (because they overlap and come into contact with each other), such forcing of the mechanism imposes considerable strain on the components of the mechanism and can cause damage. Preferably, the anti-forcing means may prevent forcing of the mechanism when the user attempts to operate the actuator to force the blades past either of the extremes. Even more preferably, the anti-forcing means may allow the user to continue to operate the actuator even after the blades have reached one or other of the extremes, but such that any further operation of the actuator after the blades have reached an extreme does not impose further force on the components of the mechanism.

hi preferred embodiments, the particular configuration of the gearbox may provide the anti-forcing means. In these embodiments, the gearbox may comprise a worm gear, a pinion gear, and a gearbox housing. The worm gear may comprise a slightly elongate generally cylindrical component having a helical screw-type thread extending along at least part of its length. The pinion gear may comprise a round component generally similar to an ordinary spur gear with radially pointing teeth, except that the teeth may only extend around a portion of the pinion gear's circumference.

The housing may have sufficient internal mounts and other sculptings for mounting the worm and pinion gears for rotating interaction therein as described below, and it may also have external sculptings adapted for securely mounting the gearbox within the frame. The housing may also have a first opening for allowing the actuator to connect to the worm gear (or to allow the shafts or linkages to connect to the worm gear in cases where the actuator is remote from the gearbox). The housing may further

have a second opening for allowing a shaft to extend out from within the housing to connect the pinion gear to the driven blade.

hi the normal operation of these preferred embodiments of the louvre system, the actuator will be operated causing rotation to be imparted (possibly through a series of connecting shafts or linkages) to the worm gear in the gearbox. The worm gear is mounted within the gearbox to rotate about its longitudinal axis in such a way that its screw threads mesh with the teeth that extend partly around the pinion gear. Hence, the rotation from the actuator is conveyed through the rotating worm gear to cause rotation of the pinion gear. The rotation of the pinion gear is then transmitted via the shaft extending out of the gearbox housing directly to the driven blade. This in turn causes corresponding rotation of the slave blades via the linking means (the control bar in preferred embodiment).

hi these embodiments, the anti-forcing means arises because the teeth on the pinion gear only extend part of the way around the pinion gear's circumference. Preferably, the teeth may extend sufficiently far around the pinion gear's circumference to enable it to rotate the blades through their full extent of rotation from one extreme to the other. Hence, it is envisaged that the teeth will generally extend slightly less than 180° around the pinion year (typically approximately 170°). Therefore, at one extreme, only the last tooth on one end of the pinion gear's row of teeth engages with the screw thread on the worm gear. Conversely, at the other extreme, only the last tooth on the other end of the pinion gear's row of teeth engages with the screw thread. Consequently, any further rotation from the actuator after the blades reach either of the extremes may still cause further rotation of the worm gear, but at these points there are no further teeth on the pinion gear for the screw thread to mesh with to continue rotating the pinion gear, and so no further rotation of the pinion gear or the blades occurs. In preferred versions of the gearbox, a spring may be provided to keep the last tooth on either end of the pinion gear's row of teeth engaged with the worm gear at the respective extremes.

hi a second aspect, the present invention resides in a gearbox for a louvre system, the gearbox comprising anti- forcing means. Preferably the gearbox of the second aspect of the invention may comprise a rotatably driven worm gear and a rotatable pinion

gear, the worm gear engaging with the pinion gear to rotate the pinion gear between two opposed extremes of rotation of the pinion gear, characterised in that the worm gear can rotate in either direction indefinitely, but the pinion gear can only be rotated between the two extremes of rotation.

In a third aspect, the present invention resides in a control bar for use in a louvre system that has a driven pivotable blade and one or more pivotable slave blades, the control arm being connectable to each of the blades via pivotable connections, the control arm linking the blades so that each of the one or more slave blades pivots in concert with the driven blade.

In a fourth aspect, the present invention resides in an end cap that is securable to an end of a louvre blade and which incorporates resilient means adapted for connecting the end of said louvre blade to a louvre frame in pivotable manner.

In a fifth aspect, the present invention resides in a louvre assembly comprising a frame, one or more louvre blades, at least one of the blades having at least one deflectable rod or pin adapted for connecting the blade to the frame, and means for changing the orientation of the one or more blades with respect to the frame when the one or more blades are connected to the frame.

In a sixth aspect, the present invention resides in a louvre assembly comprising at least one louvre blade connected to a frame, each blades being rotatable with respect to the frame between two extremes of rotation, the assembly further comprising rotatable means for changing the orientation of the at least one blade with respect to the frame wherein the rotatable means can be rotated indefinitely without causing the at least one blade to rotate past either extreme of rotation.

In a seventh aspect, the present invention resides in a louvre system comprising a frame, one or more blades, resilient means for connecting at least one blade to the frame, and an actuator for selectively changing the angle of the one or more blades relative to the frame.

In an eighth aspect, the present invention resides in a louvre system comprising a frame, one or more blades connected to the frame, an actuator for selectively changing the angle of the one or more blades relative to the frame, and anti-forcing means.

Each of the different aspects of the invention may incorporate features described with particular reference to other aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows an example of an existing louvre system used to create a window;

Figure 2 shows an example of an existing louvre system used to create shades for the windows of a house;

Figure 3 shows an example of an existing louvre system used to create a screen for the side of a verandah; Figure 4 shows a partial perspective view of a louvre system in accordance with a particularly preferred embodiment of the present invention;

Figure 5 shows the louvre system of Figure 4 with the left-hand side of the frame omitted to more clearly illustrate the control bar and the gearbox;

Figure 6 demonstrates the operation of the louvre assembly of Figures 4-5; Figure 7 is a close-up view of the gearbox, the driven blade, two slave blades and a part of the control bar (the left-hand side of the frame has again been omitted to reveal the gearbox contained therein);

Figure 8 shows an exploded top view of an end cap used in the particularly preferred embodiment of the invention presently described; Figure 9 is a cross-sectional top view of the end cap of Figure 8 when it is assembled;

Figure 10 is a front view of the end cap body of Figures 8-9;

Figure 11 is a perspective view of the end cap used on the end of the driven blade that connects to the gearbox; Figure 12 is a perspective view of an end cap of the kind used on the other end of the driven blade, and also on the ends of the slave blades;

Figure 13 is a top view looking down the inside of the frame at the gearbox. Figure 13 also shows part of the shaft which connects the gearbox to the actuator, when viewed from above;

Figure 14 is a perspective view showing, in particular, the control bar and the way it is shaped to prevent pivoting;

Figure 15 illustrates the way the control bar connects with the end caps; Figure 16 is an exploded view of the components of the gearbox; Figure 17 is a partially cut-away perspective view of the gearbox housing; and

Figure 18 shows the internal workings of the gearbox.

DETAILED DESCRIPTION OF THE DRAWINGS

As mentioned above, Figures 4-5 show partial perspective views of a louvre system 10 in accordance with a particularly preferred embodiment of the present invention.

The louvre system 10 comprises a frame having a first side 12 and a second side 14, a number of louvre blades including a driven blade 16 and a series of slave blades 18

(only two slave blades are shown in Figures 4-5), an actuator in the form of a winding handle 20, a gearbox 22, a control bar 24, and an elongate linkage member 26 that connects handle 20 with gearbox 22. It will be appreciated from Figures 4-5 that the gearbox 22 is housed inside the first side 12 of the frame.

hi the configuration shown in Figures 4-6, the louvres and the frame etc are mounted on the outside of a building, but the handle is mounted on the inside of the building's exterior wall. A small portion of the wall is shown by reference numeral 11 with the handle 20 mounted on the inside thereof. It will be appreciated that in order to connect handle 20 to the gearbox 22, the elongate linkage member 26 must extend through the wall, hi the embodiment shown, there is one main linkage member 26. However, in other embodiments, a number of linkage segments may be present. Furthermore, it will be appreciated that in some situations it may be necessary to mount the handle 20 at a position on the wall that is offset from the gearbox such that the linkage member/segnient(s) 26 may need to extend diagonally or in a deviating line to connect handle 20 to the gearbox 22. Hence, the linkage segments may be interconnected via spherical or other pivotable types of joints to enable the entire linkage to rotate in accordance with the rotation of the handle 20, even where the linkage extends diagonally or in a deviating line between the handle and the gearbox.

The general mode of operation of the louvre system 10 is shown in Figure 6. It can be seen that rotation of handle 20 in the direction indicated by arrow "A" causes the

louvre blades to rotate as shown. It will also be understood that rotating handle 20 in the opposite direction will cause the blades to rotate in the opposite direction to the one shown.

Next, Figure 7 demonstrates the way that the rotation of the handle is transmitted to cause the rotation of the blades. Firstly, it will be appreciated that the end of the linkage member/segment(s) 26 (not shown in Figure 7) insert into the square socket 28 in the gearbox to deliver rotation from the handle 20 into the gearbox 22. The internal workings of the gearbox will be described below. However, for present purposes it is sufficient to note that the rotation delivered to the gearbox via socket 28 is then transmitted to rotate driven louvre 16 as shown by the arrows. The rate of rotation of driven louvre 16 may be different to the rate of rotation delivered into socket 28 from the handle 20 because of the effective gearing ratio of the gearbox. Preferably the effective gearing ratio of the gearbox may cause the rate of rotation of the driven blade 16 to be slower than the rate of rotation of the handle. This may help to reduce the risk that small or slow rotations of the handle could cause large or rapid (potentially damaging) rotations of the blades. The same may also apply when other forms of actuators (including electronic or automatic actuators) are used in place of winding handle 20.

The driven blade 16 has a control bar 24 connected via a pivotal connection at one corner thereof, and the control bar 24 also connects in an identical pivotal manner at corresponding corners on each of the slave blades 18. hi this embodiment, the control bar 24 actually connects to the end caps on the ends of the blades closest to the first side 12 of the frame. The end caps are described further below. The control bar could also operate by connecting to the respective blades at any suitable point offset from the blades' axes of rotation.

Because control bar 24 is pivotably connected to the blades at points offset from the blades' axes of rotation, the rotation of driven blade 16 therefore pushes and pulls on the control bar 24 as shown by arrow "B" in Figure 7. Then, because control bar 24 is substantially rigid and because the slave blades 18 are pivotably mounted to the frame, the pushing and pulling indicated by arrow "B" causes the slave blades 18 to rotate in concert with the driven blade 16.

In the present embodiment, all of the louvre blades have an end cap fixed on each end of the blade. All of the end caps 30 (the "ordinary" end caps) are the same, except for the end cap 31 (the driven end cap) on the end of the driven blade 16 which connects with the gearbox 22. The driven end cap 31 is slightly different to the ordinary end caps 30 and is shown in Figure 11. The ordinary end caps 30 used on the remaining ends of the louvre blades are shown in Figures 8, 9, 10 and 12.

Referring to Figure 8, it can be seen that each ordinary end cap 30 comprises an end cap body 32, a stub axle type pin 34, a pin retaining member 36 and a small helical spring 38. The body of the end cap 32 is shaped so as to be securable on the end of the louvre blade, hi the particular embodiment shown, the end cap body comprises substantially flat flange portions 40 and recesses 42 for this purpose. However, any other shape, sculpting or means for securing the end cap on the end of the blade may be used. The pin 34 comprises two portions, namely an outer portion 44 and an inner portion 46. Both portions of the pin are substantially cylindrical but the inner portion 46 has a slightly greater diameter than the outer portion 44. The discontinuity between the inner and outer portions of the pin forms a step 48.

The pin retainer 36 has a generally rectangular elongate prism shape (best seen in Figure 12) with a flange 50 on one end (best seen in Figures 8-9). The retainer 36 also has a blind internal cylindrical bore (visible in Figure 9) that opens at the flange end 50. The diameter of the bore is slightly narrower near the flanged end than further down inside the bore, and the discontinuity between the two diameters in the bore creates a lip 52 within the bore. The diameter of helical spring 38 is sufficiently small to enable the spring to be inserted into the bore.

The cross-sectional view of the ordinary end cap 30 in Figure 9 shows the way the various components of the end cap 30 described above are assembled together. Firstly, the spring 38 is inserted into the bottom of the bore in retainer 36. The pin 34 is also inserted into the bore on top of the spring 38 thereby compressing the spring between the end of the pin's inner end 46 and the blind end of the bore. The pin 34 is secured within the bore because the step 48 on the pin engages with the lip 52 in the bore. Hence, it will be seen that the spring urges the pin 34 outwardly with respect to

the retainer 36, but the pin 34 is prevented ftom sliding out of the retainer 36 because the step 48 on the pin engages with the lip 52 in the bore. On the other hand, the pin 34 can move inwardly with respect to the retainer 36 if it is pushed further into the bore against the bias of the spring 38 (i.e. further compressing the spring). Also, because the pin 34 and the bore in the retainer 36 are both cylindrical, the pin 34 is able to rotate freely about its longitudinal axis within the confines of the bore. Finally, Figure 10 shows that the end cap 30 has a rectangular aperture 54 therein adapted for receiving the retainer 36 (the external shape of which is also rectangular).

With the above description of the ordinary end caps 30 in mind, the way in which the slave blades (and the end of the driven blade that does not connect to the gearbox) become pivotably mounted to the respective sides of the frame can be more easily understood. Each blade may be installed in the frame by first inserting the outer portion 44 of the pin 34 which protrudes from one of the end caps 30 into a corresponding receiving hole in one side of the frame. One such hole is shown by reference numeral 13 in Figure 4. Then, in order to position the pin 34 on the other end of the blade in its corresponding receiving hole on the other side of the frame, the pin on that second end can be depressed by pushing that pin 34 down into the bore against the bias of the spring 38, as described above. This moves the said second pin 34 out of the way so that it does not impact with, or it slides over, the frame as the blade is manipulated into position. Finally, when the blade is correctly positioned, the depressed pin 34 is released allowing it to snap out into engagement with its receiving hole in the frame, thereby securing the second end of the blade to the frame. Individual blades may be removed from the louvre assembly simply by reversing this process. It will be appreciated that because the pins 34 are able to rotate relative to the end caps and the blade (they rotate within the confines of the retainer 36), therefore when the blades are mounted in this way the blades are therefore able to pivot with respect to the frame.

The person skilled in the art will appreciate that in order to allow the blades to pivot as described above, the axes of rotation of the pins 34 in each end cap of each blade should be at least substantially collinear. In the embodiment shown, the axis of rotation of each of the pins on each blade (and hence the axis of rotation of the blade) runs down the centre of the blade. However, the axis need not run down the centre,

and the blades will be able to rotate as required provided that the axis of rotation of the pin on either end of each blade is at least substantially collinear.

The only difference between the driven end cap 31 (Figure 11) and the ordinary end caps 30 described above is that the driven end cap 31 has a rectangular shaft 56 inserted fixedly into the aperture 54, rather than the retainer 36 and pin 34 etc. In Figure 7, it can be seen that the fixed shaft 56 used in the driven end cap 31 extends directly into the gearbox 22 so that rotation from the gearbox is imparted directly to the driven blade 16.

As mentioned above, the control bar 24 in this particular embodiment attaches directly to the end caps on one end of each of the blades. This is most clearly illustrated in Figure 15. From Figure 15, it can be seen that the control bar 24 has a series of clips 58 which attach directly to corresponding mounts 60 provided on each end cap for this purpose. Each clip 58 has a round clasp which resili entry snaps around the correspondingly rounded shape of the mounts 60. The round shape of the clasp and the mounts enables the mounts to pivot within the clasp, thereby allowing the control bar 24 to operate as described above. The clips 58 can also be easily disconnected from the mounts 60 if it is necessary to remove individual blades.

Figure 15 also shows that the control bar 24 has a substantially straight edge 62 extending down one side thereof, and the other side has a number of protruding wings 64. Turning then to Figures 13-14, it can be seen that when the control bar is installed in the louvre system, the long edge 62 is positioned close to the edges of the blades, and the wings 64 are positioned close to the frame. Consequently, any significant rotation of the control bar 24 about its longitudinal axis (as shown by the arrow "C" in Figure 14) is prevented either by the long edge 62 coming into contact with the blades or the wings 64 coming into contact with the frame. This prevents the control bar 24 from pivoting in a manner which would cause flexure and possible damage to the mounts 60 on the end caps.

Figure 16 shows an exploded view of the components of the gearbox 22. The gearbox comprises a housing 66, a worm gear 68, a pinion gear 70 and a spring 72. Figure 16 also shows one of the linkage segments 26 used to connect the handle 20 to the

gearbox 22, including part of a spherical joint. Figure 17 shows that the gearbox housing 66 comprises two identical halves. The internal sculptings of the respective halves are such that when the halves are brought together they provide mounts for the worm and pinion gears. For example, the internal box-like portions 74 with circular cut-outs therein provide mounts for the worm gear, and the circular cutouts 76 in the shell of the casing enable the pinion gear to be secured in position by receiving the stepped notches 79 on the pinion gear (see Figure 16). The external ridges 78 on the outside of the housing operate to securely position the gearbox housing within the frame. The external ridges 78 engage with corresponding ribs 80 on the inside of the frame as shown for example in Figure 13.

Referring next to Figure 18 wherein the gearbox is shown in an assembled state, it will be appreciated that the helical screw type thread 82 on worm gear 68 meshes with the radially extending teeth 84 on pinion gear 70 such that rotation of handle 20 (and hence of worm gear 68) in the direction indicated by arrow "D" causes rotation of pinion gear 70 in the direction indicated by arrow "E". Likewise, rotation of worm gear 68 in the opposite direction to arrow "D" will cause rotation of pinion gear 70 in the opposite direction to arrow "E". However, the particular position of pinion gear 70 shown in Figure 18 is the position where in the louvre blades are at one of their extremes of rotation. In this position, it can be seen that only the last tooth on the pinion gear engages with the thread on the worm gear. Consequently, further rotation of worm gear 68 in the direction of arrow "D" will not cause the screw thread 82 to engage with any further teeth on the pinion gear, and so it will not cause any further rotation of the pinion gear in the direction of arrow "E". Hence, it is possible to continue rotating handle 20 (and hence worm gear 68) even after the louvre blades have reached an extreme of their rotation, however any such rotation will not cause any further rotation of the pinion gear or the blades, and so it will not impose any additional stress on the system.

An elongate spring 72 is mounted inside the gearbox in such a way that it becomes received within one or other of the notches 86 in the pinion gear when the pinion gear reaches one or other of the extremes of rotation (corresponding to the extremes of rotation of the louvre blades). The purpose of spring 72 is to push back against the pinion gear 70 (for example as indicated by arrow "F") so as to prevent the last tooth

on the pinion gear from continuing to rotate out of engagement with the screw thread on the worm gear. Put another way, when the pinion gear 70 is at the extreme of its rotation shown in Figure 18, further rotation of the worm gear in the direction of arrow "D" will still tend to push the last tooth away from the thread in the direction of arrow "E". However, in this position, spring 72 pushes back in the opposite direction (i.e. in the direction of arrow "F") so as to push the last tooth back into engagement with the worm thread after the worm thread has pushed it away. Those skilled in the art will appreciate that the same functionality also applies at the other extreme of rotation. Hence, this arrangement effectively gives the gearbox a "click back" function.

Maintaining the last tooth in engagement with the screw thread when the louvres are at an extreme of their rotation ensures that when the handle is operated to rotate the louvres back away from that extreme, the last tooth is in engagement with the thread and so the teeth on the pinion gear can again commence meshing with the thread on the worm gear. If the last tooth was not maintained in engagement with the thread, then the pinion gear may become totally disengaged from the worm gear preventing further rotation of the louvre blades.

Those skilled in the art will appreciate the various other changes and modifications can be made to the particular embodiment described without departing from the spirit and scope of the invention.