PRIORITY DOCUMENTS

[0001] The present application claims priority from Australian Provisional Patent Application No. 2017902381 titled "A LOW PROFILE RETROFITABLE RETRACTABLE SCREEN SYSTEM" and filed on 21 June 2017, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to a retractable screen system that can be retrofitted to windows. BACKGROUND

[0003] It is a common requirement to provide a screen in relation to doors or windows. For example, in the case of a window, there may be provided a horizontal or vertical sliding window panel which is used to open the window or a hinged window panel with a hinge in the upper edge and that is opened by using a winding mechanism to pivot the lower part of the window panel about the upper hinge, or a similarly hanging panel hinged on the vertical edge. Conventionally, a screen is used to prevent ingress of insects or debris while at the same time providing ventilation. Also, screens are generally open mesh which also provides visibility through the screen.

[0004] One disadvantage in the case of windows is that existing screen systems cover one half or a number of portions of the window. They are generally permanently installed screens so that a portion of the window provides a clear view while for the remainder of the window, the user will have to look through the window and screen. In some cases the screen covers the entire window panel (for example in the case of a hinged window panel) so that the user will have to look through the window and screen. It would be much more desirable to have simply glass unobstructed by any screens.

[0005] Also, the screens are normally provided in a frame which is then mounted to the window. This then results in restricted access to the window for the purpose of cleaning or other maintenance.

[0006] A screen system was previously developed to address these issues and enable a screen system to be retrofitted to a window or door opening. Whilst this system is applicable to most doors and windows, the system can be bulky for small windows such as those found in caravans, recreational vehicles and mobile homes. In such cases space is often very limited and the previous system is over engineered for these requirements. In one previous system the caravan window comprises a permanently fixed insect screens (or no screen) and a gravity driven screen which is held in place purely through friction. This only allows the use of a single screen (either an insect screen or a blind). Also as the system wears it tends not to hold its position (and thus will fully extend across the opening). Another system used in caravans comprises a spring within the spindle which acts to retract the screen, and a braking arrangement in the screen handle (screen edge) to keep the screen in an extended position. This comprises a release mechanism that withdraws/extends two rods (brakes) out/into a series of parallel recesses in the side frames. The rods are spring driven to drive them into the recesses and thus prevent movement (eg retraction) of the blind. To operate the screen the user squeezes the brake handle to retract the two side rods (brakes) from the recesses and moves the screen before releasing the brake handle to drive the brake members (via brake springs) into new recesses. This movement is done against the retracting bias force of the spindle spring, which is typically quite strong. If the user accidentally lets go the blind with rapidly fully retract which can be loud and/or hazardous to the system. Additionally (or as a result of rapid retraction) the blind can get out of alignment if the two side brakes engage with non matching recesses (ie those not in the same plane). Further as this is a spring loaded spindle, users are advised against driving with the blinds down, as bumps may cause one or both of the brakes to fail allowing retraction of the screen. Thus other existing screen systems tend to be bulky and/or difficult to use, particular for elderly occupants who may have limited strength or mobility, and are also prone to failure.

[0007] There is thus a need to provide an improved screen system that can be fitted to windows such as those found in caravans and the like, or at least provide a useful alternative to existing systems.

SUMMARY

[0008] According to a first aspect, there is provided an apparatus comprising:

a screen support assembly comprising a frame defining a screen opening, the frame comprising a first end, a second end, a first side and a second side, the first side comprising a first slot and second side comprising a second slot, wherein the frame is either adapted to be retrofitted to an existing window frame, or forms part of a window frame;

a first roller assembly mounted in the first end comprising:

a first screen;

a first spindle rotatably mounted adjacent the screen opening around which the first screen is wound so that the first screen can be unwound from or wound onto the first spindle; and a first spindle rotation assembly for rotating the first spindle comprising a first spindle pulley;

a first screen end panel located at the distal end of the first screen and extending laterally into the first slot in the first side and the second slot in the second side;

a first guide assembly and tension adjustment arrangement located in the first side and comprising: a first operative means, a first shuttle pulley, a first anchor pulley, a first end guide, an elastic member connected between the first shuttle pulley and an anchor point, wherein

the first operative means is connected between the first spindle pulley and the lateral end of the first screen end panel, and follows a path from the first spindle pulley to the first shuttle pulley, from the first shuttle pulley to the first anchor pulley, from the first anchor pulley to the first end guide, and from the first end guide to the lateral end of the first screen, and the first shuttle pulley is distal of the first anchor pulley with respect to the first spindle pulley, and the first end guide is distal of the maximum extended location of the first screen end panel, and

as the first screen is extended across the screen opening, the first screen is wound off the first spindle and the operative means is wound onto the first spindle pulley, and as the screen is retracted across the screen opening the first screen is wound onto the first spindle and the first operative means is wound off the first spindle pulley, and

the elastic member adjusts the tension in the first operative means as the first screen is wound and unwound from the first spindle.

[0009] In one form, the apparatus further comprises:

a second roller assembly mounted in the second end comprising:

a second screen;

a second spindle rotatably mounted adjacent the screen opening around which the second screen is wound so that the second screen can be unwound from or wound onto the second spindle; and

a second spindle rotation assembly for rotating the second spindle comprising a second spindle pulley;

a second screen end panel located at the distal end of the second screen and extending laterally into the first slot in the first side and the second slot in the second side;

and the first guide assembly and tension adjustment arrangement further comprises:

a second operative means, a second shuttle pulley, a second anchor pulley, a second end guide, and the elastic member is connected between the first shuttle pulley and the second shuttle pulley, wherein

the second operative means is connected between the second spindle pulley and the lateral end of the second screen end panel, and follows a path from the second spindle pulley to the second shuttle pulley, from the second shuttle pulley to the second anchor pulley, from the second anchor pulley to the second end guide, and from the second end guide to the lateral end of the second screen, and the first shuttle pulley is distal of the first anchor pulley with respect to the first spindle pulley, and the first end guide is distal of the maximum extended location of the first screen end panel, and

as the second screen is extended across the screen opening, the second screen is wound off the second spindle and the operative means is wound onto the second spindle pulley, and as the screen is retracted across the screen opening the second screen is wound onto the second spindle and the second operative means is wound off the second spindle pulley, and

the elastic member adjusts the tension in the first operative means as the first screen is wound and unwound from the first spindle and adjusts the tension in the second operative means as the second screen is wound and unwound from the second spindle.

[0010] In one form, the first operative means is a cable, the second operative means is a cable, and the elastic member is a spring.

[001 1] In one form, each of the first shuttle pulley, the first anchor pulley, the second shuttle pulley, the second anchor pulley, the first spindle pulley and the second spindle pulley are located in a first plane, and first end guide and second end guide are located in a second plane parallel to the first plane and proximal to the screen opening.

[0012] In a further form, a third plane comprises a proximal side of the first spindle pulley, a proximal side of the second spindle pulley, a distal side of the first end guide, and a distal side of the second end guide.

[0013] In a further form, the first side further comprises an extrusion defining the first slot and a third slot, wherein each of the first shuttle pulley, the first anchor pulley, the second shuttle pulley, and the second anchor pulley each comprise a base portion which is slidably received in the third slot, and the axis of the first shuttle pulley, the first anchor pulley, the second shuttle pulley, and the second anchor pulley are each orthogonal to the slot.

[0014] In a further form, the first shuttle pulley and second shuttle pulley are identical and each comprise a pulley, spring anchor, and a base comprising a T shaped section adapted to be retained within the third slot, and the first anchor pulley and the second anchor pulley are identical and each comprise a pulley, a grub screw and a base comprising a T shaped section adapted to be retained within the third slot, wherein the grub screw is configured to pass through the base to secure the anchor pulley to the third slot.

[0015] In a further form, the first end guide and the second end guide are identical and each comprise a pair of vertically separated cylindrical guides, each mounted on a shaft extending from a corner support wherein the cylindrical guides are co-planar and each axis is vertically aligned, and the vertical separation of the pair of vertically separated cylindrical guides is less than or equal to the diameter of the first spindle pulley and the less than or equal to the diameter of the second spindle pulley.

[0016] In a further form, the extrusion further comprises a flange defining an upper surface of the first slot, and an uppermost edge of an upper cylindrical guide of a pair of vertically separated cylindrical guides is vertically above an uppermost edge of the shuttle pulleys, and the lowermost edge of a lower cylindrical guide of a pair of vertically separated cylindrical guides is vertically below a lowermost edge of the shuttle pulleys and above the plane or in the plane of the flange.

[0017] In one form the apparatus further comprises a second guide assembly and tension adjustment arrangement located in the second side, wherein the second guide assembly and tension adjustment is a mirror image of the first guide assembly and tension adjustment arrangement.

[0018] According to a second aspect, there is provided an apparatus comprising:

a screen support assembly defining a screen opening and adapted for insertion into and removal from a frame comprising a first end, a second end, a first side and a second side, the first side and second side each comprising a slot;

a first roller assembly mounted in the first end comprising:

a first screen;

a first spindle rotatably mounted adjacent the screen opening around which the first screen is wound so that the first screen can be unwound from or wound onto the first spindle; and a first spindle rotation assembly for rotating the first spindle comprising a first spindle pulley;

a screen end panel located at the distal end of the first screen and extending laterally into the slot in the first side and the slot in the second side;

a tension adjustment arrangement fixed to or located over the screen end panel and comprising an elastic member connected to a plurality of removable linkage members;

an operative means connected between the tension adjustment arrangement and the first spindle rotation assembly, wherein the operative means wraps around the first spindle pulley, such that as the screen is extended across the screen opening, the screen is wound off the first spindle and the operative means is wound onto the first spindle pulley, and as the screen is retracted across the screen opening the screen is wound onto the first spindle and the operative means is wound off the first spindle pulley; a first guide assembly comprising a first guide mounted to the first side, a second guide mounted on the screen end panel wherein first guide is mounted in a location distal of the second guide when the screen is fully extended across the screen opening and redirects the operative means from the first spindle pulley to the second guide, and the second guide guides the operative means from the first guide to the first end of the of the tension adjustment arrangement, and the tension adjustment arrangement adjusts the tension in the operative means as the screen is wound and unwound from the first spindle.

[0019] In one form, the first guide comprises a first pulley, and the second guide comprises a second pulley wherein an axis of the first pulley is parallel to a rotation axis of the first spindle pulley, and an axis of the second pulley is normal to the screen end panel and rotation axis of the first spindle pulley. [0020] In a further form, the first side comprises a front cover member parallel to the screen opening and a side member orthogonal to the screen opening and the slot is defined between the front cover member and a slot wall member extending from the side member and the first guide is mounted to the side member above the slot wall member, and the second guide is mounted on the screen end panel such that the second pulley is adjacent to the slot so that the path of the operative means from the first spindle pulley to the second pulley is located substantially over the slot wall member.

[0021 ] In one form, the apparatus further comprises

a second roller assembly mounted in the second end comprising:

a second screen;

a second spindle rotatably mounted adjacent the screen opening around which the second screen is wound so that the second screen can be unwound from or wound onto the second spindle; and

a second spindle rotation assembly for rotating the second spindle comprising a second spindle pulley;

a second screen end panel located at the distal end of the second screen and extending laterally into the slot in the first side and the slot in the second side;

a second tension adj ustment arrangement fixed to or located over the second screen end panel and comprising a second elastic member connected to a plurality of second removable linkage members; a second operative means connected between the second tension adjustment arrangement and the second spindle rotation assembly, wherein the second operative means wraps around the second spindle pulley, such that as the second screen is extended across the screen opening, the second screen is wound off the second spindle and the second operative means is wound onto the second spindle pulley, and as the second screen is retracted across the screen opening the second screen is wound onto the second spindle and the second operative means is wound off the second spindle pulley;

a second guide assembly comprising a third guide mounted to the first side, a fourth guide mounted on the second screen end panel wherein third guide is mounted in a location distal of the fourth guide when the second screen is fully extended across the screen opening and redirects the second operative means from the second spindle pulley to the fourth guide, and the fourth guide guides the second operative means from the third guide to the first end of the of the second tension adjustment arrangement, and the second tension adjustment arrangement adjusts the tension in the second operative means as the second screen is wound and unwound from the second spindle.

[0022] In a further form, the third guide comprises a third pulley, and the fourth guide comprises a fourth pulley wherein an axis of the third pulley is parallel to the axis of the first pulley, and an axis of the fourth pulley is parallel to the axis of the second pulley. [0023] In a further form, the fourth guide is mounted on the second screen end panel such that the fourth pulley is adjacent to the slot so that the path of the second operative means from the second spindle pulley to the fourth pulley is located substantially over the slot wall member.

[0024] In one form, the elastic member is a spring, the removable linkage members are chain loops, and the tension adjustment arrangement is fixed to the screen end panel. In an alternative form the elastic member is a spring, the removable linkage members are a ball chain, and a retaining arrangement is located on the screen end panel and configured such that a length of the ball chain between the spring and retaining arrangement can be varied to allow adjustment of the tension in the spring.

[0025] In one form, the first spindle is rotatably mounted to the first side, and the first roller assembly further comprises a third spindle rotatably mounted to the second side and a third spindle rotation assembly for rotating the third spindle comprising a third spindle pulley which rotates about the rotation axis of the first spindle pulley, and the apparatus further comprises:

a third operative means connected between a second end of the tension adjustment assembly and the third spindle rotation assembly, wherein the operative means wraps around the third spindle pulley, such that as the screen is extended across the screen opening, the screen is wound off the third spindle and the operative means is wound onto the third spindle pulley, and as the screen is retracted across the screen opening, the screen is wound onto the third spindle and the operative means is wound off the third spindle pulley;

a third guide assembly comprising a fifth guide mounted to the second side, a sixth guide mounted on the screen end panel wherein the fifth guide is mounted in a location distal of the sixth guide when the screen is fully extended across the screen opening and redirects the third operative means from the third spindle pulley to the sixth guide; and

wherein the first end of the tension adjustment is proximal to the first side and the second end of the tension adj ustment arrangement is proximal to the second side.

[0026] In a further form, the removable linkage members are chain loops, and the tension adjustment arrangement is located over the screen end panel.

BRIEF DESCRIPTION OF DRAWINGS

[0027] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:

[0028] Figure 1 A is a front view of an apparatus for retrofitting a retractable screen system into a window frame opening according to an embodiment; [0029] Figure IB is a rear view of the apparatus of Figure 1A showing a first screen and a second screen, both in retracted positions;

[0030] Figure 2 is a schematic rear view of the top and bottom corners of the apparatus of Figure 1A;

[0031 ] Figure 3 is a schematic rear view of the top and bottom corners of another embodiment of an apparatus for retrofitting a retractable screen system into a window frame;

[0032] Figure 4 is sectional profile view of the top corner of the apparatus of Figure 1A;

[0033] Figure 5A is a schematic side view of the path of the cords in a dual screen arrangement according to an embodiment;

[0034] Figure 5B is a schematic top view of the path of the cords in a dual screen arrangement according to an embodiment;

[0035] Figure 5C is a schematic side view of the path of the cord in a single screen arrangement according to an embodiment;

[0036] Figure 5D is a schematic top view of the path of the cord in a single screen arrangement according to an embodiment;

[0037] Figure 6A is a perspective view of a pulley guide arrangement according to an embodiment;

[0038] Figure 6B is a front view of the pulley guide arrangement of Figure 6A;

[0039] Figure 6C is a first side view of the pulley guide arrangement of Figure 6A

[0040] Figure 6D is a rear view of the pulley guide arrangement of Figure 6 A;

[0041 ] Figure 6E is a second side view of the pulley guide arrangement of Figure 6A;

[0042] Figure 7A is a rear view of a screen assembly within a frame according to an embodiment;

[0043] Figure 7B is a close up view of the adjustment mechanism tension adjustment arrangement of the screen assembly in Figure 7A;

[0044] Figure 8A is an isometric view of another embodiment of a dual screen arrangement according to an embodiment; [0045] Figure 8B is a rear perspective view of one side of the dual screen arrangement shown in Figure 8A;

[0046] Figure 8C is a top perspective view of one side of the dual screen arrangement shown in Figure 8A;

[0047] Figure 8D is a sectional view of one side of the dual screen arrangement shown in Figure 8A;

[0048] Figure 8E is scaled top view of a side of the dual screen arrangement shown in Figure 8A with covers removed;

[0049] Figure 8F is a perspective view of the pulleys and tension adjustment arrangement of one side of the dual screen arrangement shown in Figure 8A;

[0050] Figure 8G is a an exploded perspective view of one side of the dual screen arrangement shown in Figure 8A;

[0051 ] Figure 8H is a sectional view through one a side of the dual screen arrangement shown in Figure 8A;

[0052] Figure 81 is a perspective view showing the path of a single cord in the dual screen arrangement shown in Figure 8A;

[0053] Figure 9A is a perspective view of a shuttle pulley arrangement according to an embodiment;

[0054] Figure 9B is a front view of the shuttle pulley arrangement of Figure 9A;

[0055] Figure 9C is a first side view of the shuttle pulley arrangement of Figure 9A

[0056] Figure 9D is a rear view of the shuttle pulley arrangement of Figure 9A;

[0057] Figure 9E is a second side view of the shuttle pulley arrangement of Figure 9A;

[0058] Figure 9F is a perspective view of an anchor pulley arrangement according to an embodiment;

[0059] Figure 9G is a front view of the anchor pulley arrangement of Figure 9F;

[0060] Figure 9H is a first side view of the anchor pulley arrangement of Figure 9F;

[0061] Figure 91 is a rear view of the anchor pulley arrangement of Figure 9F; and [0062] Figure 9 J is a second side view of the anchor pulley arrangement of Figure 9F.

[0063] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0064] Various embodiments of a retractable screen system for retrofitting or installation by insertion into a frame of a window such as those found in caravans and mobile homes. Embodiments of this system are compact and easy to use enabling use by elderly occupants who may have limited strength or mobility. Various embodiments allow the inclusion of a single screen such as a block out blind or insect screen, or a dual screen arrangement such as a block out blind and an insect screen.

[0065] Figure 1 A is a front view of an apparatus 1 for retrofitting a retractable screen system into a window frame opening according to an embodiment. In this embodiment the apparatus 1 comprises a screen support assembly 10 comprised of a first end 1 1, a second end 12, a first side 13 and a second side 14 which define a screen opening 15. A first screen 21 , which in this embodiment is a block out blind can be extended and retracted from the first end 11, and a second screen 31, which in this embodiment is an insect screen, can be extended and retracted from the second end 12. The first screen 21 ends in a screen end panel 22 which has a handle 23 located on the front face (accessible to the user) and the second screen 31 ends in a second screen end panel 32 which has a second handle 33 located on the front face.

[0066] Figures IB through 4 show various additional views to illustrate various aspects of apparatus. Figure IB is a rear view of the apparatus of Figure 1A showing the first screen 21 and a second screen 31 in retracted positions. To further illustrate the mechanism and function of the tension adjustment arrangement and the path of a cord from the tension adjustment arrangement to spindle pulley, Figure 2 is a schematic rear view of the top and bottom corners of the apparatus of Figure 1A, Figure 4 is sectional profile view of the top corner of the apparatus of Figure 1 A, and Figures 5A and 5B show views of the path of the cords. Figure 3 and Figures 5C and 5D show another embodiment with a single screen (blind or insect screen). To illustrate various aspects of the apparatus these embodiments will now be discussed with reference to Figures 1 A to 5D.

[0067] A first roller assembly is mounted in the first end 11 and comprises a first spindle 41 which is rotatably mounted adjacent the screen opening 15. The first screen 21 is wound (or rolled) onto and off the spindle 41 as the screen is retracted and extended across the screen opening 15. A spindle pulley 42 is co-axially located on the spindle, and a spindle mount 43 is formed as a cavity in the side 14 near the top corner of the screen support assembly 10. This receives an axial projection from the spindle 41 and defines the rotation axis of the spindle 41 and spindle pulley 42. The cavity is provided with a curved access path from an insertion aperture in the rear of the side member 14 to allow insertion of the spindle and screen. An additional equivalent spindle, spindle pulley and spindle mount is also provided in the second side 13. Similarly a second roller assembly is provided for the second screen 31 in the lower corner or side member 14 (comprising second spindle 71, second spindle pulley 72 and second spindle mount 73) and an additional spindle, spindle pulley and spindle mount is also provided in the second side 13.

[0068] A screen end panel 22 is located at the distal end of the screen 21 . This is a rigid panel that extends laterally into a slot 17 formed in the first side and a similar slot in the second side 14. As shown in Figure 4, the side 14 comprises a front cover member 18 which is parallel to the screen opening 15 and a side member 19 which is orthogonal to the screen opening. The slot 17 is formed and defined between the front cover member 18 and a slot wall member 16 extending from the side member 19. As shown in Figure 4 the side member 19 comprises projections which form a friction fit with the slot wall member 16 to support the slot wall member 16. An equivalent (second) slot is provided in the second side 13 so that the two slots guide the path of the screen as it is extended and retracted.

[0069] To assist in the extension and retraction of the screen an operative means 51, such as a cord, cable, chain, ribbon, or other flexible linking member is connected between a tension adjustment arrangement 50 and the first spindle rotation assembly. More complicated multi-component linkage arrangement comprising linked flexible and rigid members for example with the flexible members passing around pulleys and rigid members spanning the gap between pulleys could also be used. For ease of description the operative means 51 will be referred to as a cord, although it is to be understood that the cord shown in the various Figures could be replaced with an alternative operative means 51.

[0070] The cord 51 wraps around the first spindle pulley 42. As the screen 21 is extended across the screen opening 15, the screen is wound off the first spindle 41 and the cord 51 is wound onto the first spindle pulley 42. Conversely as screen 21 is retracted across the screen opening 15, the screen is wound onto the first spindle 41 and the cord 51 is wound off the first spindle pulley 42.

[0071] In many prior art systems, the spindles are tapered and/or grooved so that the length of the cable remains constant during winding and unwinding so that the tension in the cable is constant. However this tends to require large spindles, and is not suitable to compact and low profile arrangements such as that used in caravans. Thus a tension adjustment arrangement 50 is also provided and is fixed to or located over the screen end panel 22. A first guide assembly is also provided to guide the cord 51 from the spindle pulley 42 to the tension adjustment arrangement 50. The tension adjustment arrangement 50 adjusts the tension in the cord as the screen 21 is wound and unwound from the first spindle 41. The tension adjustment arrangement comprises an elastic member 55 connected to a plurality of removable linkage members 54. In this embodiment the elastic member 55 is metal spring and the removable linkage members 54 are metal chain loops each formed from a single piece of wire bent into two loops with the first loop orthogonal to the second loop. As the screen 21 is extended and retracted, the cord 51 is wound onto and off the spindle pulley 42 and the path length of the cord 51 from the spindle pulley to the tension adjustment arrangement changes. The spring 55 elastically compensates for changes in tension in the cord due to this change in path length to assist providing smooth movement of the screen over the full range. To provide further tension adjustment, the metal chain loops can be individually removed or added. This allows a degree of customisation to be provided to suit the specific window size (ie the same spring can be used for different window sizes), as well for maintenance in case the elasticity of the spring changes over time (eg through use).

[0072] As mentioned above a first guide assembly guides the cord 51 from the spindle pulley 42 to the tension adjustment arrangement 50 and comprises a first guide 52 which is mounted to the first side 14, a second guide 53 which is mounted on the screen end panel 22. The first guide 52 is mounted in a location distal of the second guide 53 when the screen 21 is fully extended across the screen opening 15 and redirects the cord 51 from the first spindle pulley 42 to the second guide 53. The second guide 53 guides the cord from the first guide 52 to the first end of the of the tension adjustment arrangement 50.

[0073] In this embodiment the first guide 52 comprises a first pulley, and the second guide 53 comprises a second pulley. The axis of rotation of the first pulley 52 is parallel to a rotation axis of the first spindle pulley 42, and the axis of the second pulley 53 is normal to the screen end panel 22 and rotation axis of the first spindle pulley 42. As can be seen in Figure 4B the first guide 52 is mounted to the side member 19 above the slot wall member 16, and the second guide 53 is mounted on the screen end panel 22 such that the second pulley is adjacent to the slot 17 so that the path of the cord from the first spindle pulley 42 to the second pulley 53 is located substantially over the slot wall member 16.

[0074] In this embodiment the same pulley guide arrangement is used for the first and second guides (and other guides as outlined below). This facilitates manufacturing as the same design can be reused for different components. The design of this pulley guide is shown in Figures 6A to 6E which are perspective 601 , front 602, first side 603, rear 604, and second side 605 views. This pulley guide arrangement comprises a body 612 which supports a pulley 614 at one end of the body and mounting surface 616 at the other end of the body. A support 618 is formed or connected to the base of the body 612, and is formed with a T shaped profile to form two side slots in the base. A fixing means 619 such as a rotatable screw arrangement which can pass through the body 612 and support 61 8 is also provided to allow the pulley mount arrangement to be fixed in a particular location, for example to support panel 22 or side member 19 as shown in Figure 4. The two side slots in the base which can be used to assist in aligning or constraining the location of the pulley guide. For example the side member 19 can be provide with flanged projections (or a similar arrangement) which are retained in the slots allowing the pulley guide to be moved in only one axis (eg vertically) prior to fixing the location. [0075] In this embodiment a second screen 31 such as insect screen is also provided, with similar components to the arrangement for the first screen 21. A second roller assembly 70 is provided with a second spindle 71 which is rotatably mounted adjacent the screen opening in the second end 12 allowing the second screen 31 to be unwound from or wound onto the second spindle 71. A second screen end panel 32 is located at the distal end of the second screen 31 and extends laterally into the slot 16 in the first side 14 and the slot in the second side 13. A second operative means 61 (eg cord, cable, chain, ribbon, or other flexible linking member), hereafter cord 61 for simplicity, is connected between the second screen end panel 32 and the second spindle rotation assembly 70.

[0076] The second cord 61 wraps around the second spindle pulley 72. As the second screen 31 is extended across the screen opening 15, the screen 31 is wound off the second spindle 71 and the second cord 61 is wound onto the second spindle pulley 72. Conversely as second screen 31 is retracted across the screen opening 15, the screen 31 is wound onto the second spindle 71 and the second cord 61 is wound off the second spindle pulley 72. A second guide assembly comprises a third guide 62 mounted to the first side, and a fourth guide 63 mounted on the second screen end panel 32. The third guide 62 is mounted in a location distal of the fourth guide 63 when the second screen 31 is fully extended across the screen opening 15 and redirects the second operative means 61 from the second spindle pulley 72 to the fourth guide 63. A second tension adjustment arrangement 70 is located over (although it could be fixed to) the second screen end panel 31. This comprises a second elastic member 65 (eg spring) connected to a plurality of second removable linkage members 64 (eg chain loops). The second cord 61 operative member is connected to a first end of the second tension adjustment arrangement 70 and the fourth guide 63 guides the second cord 61 from the third guide 62 to the first end of the of the second tension adjustment arrangement 70, and the second tension adjustment arrangement 70 adjusts the tension in the cord 61 as the second screen 32 is wound and unwound from the second spindle.

[0077] This first side 14 with the two screens 21 31, and associated roller assemblies, tension adjustment arrangements, and guide assemblies is shown in Figure 2. It can be seen that the first spindle pulley 41, the second spindle pulley 72, the first guide pulley 52 and third guide pulley 62 have parallel rotation axes and are aligned so that the cords are following similar paths (eg vertically aligned in Figure 2). The axes of the second guide and fourth guide are aligned and are normal to the screen end panels. As noted above the guides can be pulley guide arrangements as shown in Figures 6A to 6E. The fourth guide 63 is mounted on the second screen end panel 32 such that the fourth pulley 63 is adjacent to the slot 17 so that the path of the second cord from the second spindle pulley 72 to the fourth pulley 63 is located substantially over the slot wall member 16.

[0078] Figures 5A and 5B are schematic side and top views of the path of the cords 51 61 . The path of the cords is further illustrated in Figure 2 and 4. From these Figures it can be seen the spindle pulleys are larger diameter than the guide pulleys, such that the cords 51 and 61 are elevated and distal of the front cover member 18 and follow inclined paths and cross over (forming an X) before they are double backed by first and second guides 52 62 . After doubling back through first and third guides 52 62 the cords 51 61 are located just above slot wall member 16, and follow slanted (or inclined) paths towards the third and fourth guide members 53 63 (ie deflected towards the screen opening 15 and away from side 14). That is the path initially drops in height above the slot wall member whilst maintaining a constant distance from the side 14, and after doubling back stays at the same height with respect to the slot wall member 16, but diverges away from the side 14. When installed this height drop is change in the dimension or direction normal to the plane of the screen opening 15 and window panel, and represents the thickness dimension of screen assembly. The drop height of the path of the cord 81 is shown in Figure 5A, and the lateral width 82 of the path of the cord is shown in Figure 5B. In this context lateral is in the plane parallel to the screen opening 15 and slot wall member 16. The total height or (installed) thickness 83 of the side 14 and slot depth 86 are also shown in Figure 5A, and Figure 5B shows the lateral width 84 of the slot wall member 16 and the width 85 of the side wall including cover portion 18 (these widths are in the plane parallel to the screen opening 15). The present arrangement allows the vertical drop 81 and lateral width 83 to be kept small, allowing the frame thickness 83 and side wall widths 85 to be kept small, enabling use in small frames such as windows in caravans and mobile houses.

[0079] In this embodiment the guide pulleys are 12mm in diameter, the slot depth 86 is 5mm and the vertical drop height 81 of the path of the cord 81 is around 16mm (4mm above the pulley, 12mm around the pulley). In this embodiment the spindle pulley is 38mm in diameter, but in other embodiments this could be made smaller to reduce the profile such as around 30mm. The size of the spindle pulley 38mm will be dictated by the size of the window opening, and thus the amount of screen material that must be capable of being rolled onto it. In one embodiment the same size pulley may be used for multiple size windows to reduce the part count and increase manufacturing efficiency and in other embodiments a range of spindle pulleys may be used to enable smaller profiles for smaller windows. It is to be understood that these sizes are representative of this embodiment, and that in other embodiments different size pulleys could be used.

[0080] As mentioned above and illustrated in Figure IB, the second side 13 comprises similar components in a similar arrangement to those on the first side. For example the first roller assembly further comprises a third spindle rotatably mounted to the second side and a third spindle rotation assembly for rotating the third spindle, for example using a third spindle pulley. The third spindle pulley rotates about the rotation axis 44 of the first spindle pulley 42. A further operative means (eg cord) and guide assembly is also provided in the second side to assist movement of the screen. In the embodiment shown in Figure 1 B, the tension adjustment is located over the screen end panel 22 and a single spring is used in the tension adjustment arrangement for both sides. That is the first end of the spring (or tension adjustment) is proximal to the first side 14 and the second end of the tension adjustment arrangement is proximal to the second side 13. Alternatively two springs could be used, with each anchored to the screen end panel 22.

[0081] The above embodiments provide an effective and low profile retrofitable system for providing a retractable screen. However, other variations and embodiments are possible, for example including additional components or varying the location of the components. Figure 7A show a rear perspective view of a screen assembly according to another embodiment. In this embodiment the window is a wide window as is found in many caravans and the screen assembly further includes an insect screen retaining arrangement to assist in retaining the insect screen 21 when extended across the screen opening 15.

[0082] The screen assembly 1 shown in Figure 7A is fitted within a window frame housing 2 which acts as a cover and support to the screen assembly 1. The window frame housing 2 defines an inner frame edge comprising upper and lower inner edges 3 and side edges 5. The window frame housing further comprises a plurality of clips located on the underside of the frame housing 2 for attaching the window frame housing to supports (eg tubes) located around the window. In this embodiment the window is wide compared to the height (ie side 5 is longer than the top 3). Typical height to width ratios for caravan windows range from 0.33 to 1.3 with most heights between 300mm and 900mm and widths between 500mm and 1450mm.

[0083] The screen assembly 10 can be formed as a frame configured to sit within the window frame housing 2 and fixed in place with a plurality of mounting arrangements. The screen assembly mounting arrangement comprises a flange 91 extending from the second side and a fastener 92 in the form of a screw that screws the flange to support surface formed in the attachment window frame housing 2. This is just adjacent a clip 4. In this embodiment two flanges are located on each of the first and second sides 13 and 14, each near the first and second ends 1 1 and 12. In this embodiment the distal part of the first edge 22 comprises a soft trim 26 and the distal part of the second edge 32 comprises a soft trim 36. The soft trim may be natural fibre (wool), synthetic fibre or blend. Further the second guide 53 is a pulley mounted via a fastener through the pulley axis.

[0084] In embodiments such as this where the blind 21 is in the top side 11 and the insect screen 31 is in the lower side 12 and the window opening is wide (as in this embodiment) or the insect screen is heavy, there may be insufficient frictional engagement between the insect screen and the support assembly, and/or tension on the insect screen to keep the insect screen in the extended position to resist the gravitation force acting on the extended screen. Thus in this embodiment the screen apparatus further comprises a screen retaining arrangement. In this embodiment two magnets 34 are fitted to inner surface of the first edge of the insect screen panel 32, and two retaining plates 35 mounted to the top side 1 1 and aligned with the magnets 34. When the insect screen is fully extended across the window opening 15, the magnets 34 engage with the retaining plates 35 to hold the insect screen in position. [0085] The screen retaining arrangement is only required for the lower screen, as typically the upper screen system is less affected by the gravitational force (there is greater friction or tension forces to resist the gravitational force). Thus typically the screen retaining arrangement is an insect screen retaining arrangement as an insect screen is typically only required to be fully extended or fully retracted whereas the blind may be required to stop at various positions across the opening 15 (and thus the insect screen is located in the lower side 12).

[0086] The use of magnets allows the user to simply pull the handle 33 down to overcome the magnetic attraction between the magnet 34 and retaining plate 35 when the user wishes to retract the insect screen 31. A single located in the centreline or two magnets is sufficient for most applications, but more magnets can be used if required (eg 3, 4, 5 or more). Other reversible fastening arrangements can also be used such as clips, studs, catches, etc, that will engage when the screen is fully extended across the opening, and can easily be disengaged by the user when they wish to retract the insect screen 31. In one embodiment the retaining plates 15 (or engaging part) could be located on the blind end panel 22 rather than mounted to the top side 1 1 to bind the lower insect screen to the upper blind screen. In another embodiment these reversible fastening arrangements may be located within the sides 13 14 for example in slot 17. In another embodiment screen retaining arrangement comprises adapting the lateral edge of the screen end panel 32 to act as an engaging part with a retaining part in the slot 17 or side 13 14. In one embodiment the lateral edge of the screen end panel 32 or the slot is adapted to increased friction between the screen edge panel 32 and slot to assist in retaining the insect screen in the extended position. Similarly the side extrusion could be designed to have increase friction.

[0087] In this embodiment an alternative tension adjustment arrangement is used to the embodiment shown in Figures 1 A to 5C. Figure 17B is a close up view of the adjustment mechanism of the tension adjustment arrangement on the insect screen end panel 32. As can be seen in these Figures the removable linkage members in the tension adjustment arrangement are a ball chain 54 located distal of the spring 55 (with respect to the side) which is directly attached to the cord 51 . The ball chain is comprised of balls on a chain or cord such that the diameter of the balls is greater than the diameter of the chain or cord. To adj ust the tension, a retaining arrangement 54 in the form of a slotted flange attached to the inner surface of the screen end panels 22 32 is used. The width of the slot is greater than the width of the chain (or cord) but less than the diameter of the balls and thus to adjust the tension a user can simply grab the distal trailing end of the ball chain and place a different part of the chain in the slot to define a new length of the ball chain between the slot 56 and spring 55. Additionally the diameter of the balls can be chosen so that they are less than the internal diameter of the spring, so excess ball chain length can be inserted inside the spring 55 65. That is the length of the ball chain can be adjusted at both ends. An additional advantage of this arrangement is that the occupant can easily adjust the tension, by simply opening the window and leaning into the window to view the interior side, removing any cover (if present) and then grasping the trailing edge of the ball chain and adjusting the length of the ball chain between the spring and retaining arrangement (ie by placing a different ball behind the slot to alter the length).

[0088] In some embodiments the apparatus uses a single screen, which may be a blind or an insect screen, and extend from either the first end 1 1 or second end 12. Figure 3 is a schematic rear view of the top and bottom corners of such an embodiment, and Figures 5C and 5D shows schematic side and top views of the path of the cord in this single screen embodiment. Parts numbers are as for the dual screen embodiment.

[0089] Figure 8A is an isometric view of another embodiment of a dual screen arrangement 1 according to an embodiment. In this embodiment the system can be retrofitted to an existing window frame or integrated with the window during manufacture. The system comprises a screen support assembly which comprises a frame that defines a screen opening. The frame comprises a first end 1 1, a second end 12, a first side 13 and a second side 14. In the retrofit case this frame fits over the window frame, and in the integrated case this frame forms part of the window frame. Figures 8B and 8C show rear and top perspective view, and Figure 8D is a sectional view of one side of the dual screen arrangement shown in Figure 8A. Figure 8E is scaled top view of a side of the dual screen arrangement shown in Figure 8A with covers removed and scaled to exacerbate the paths of the cords to facilitate viewing of the respective paths. Figure 8F is a perspective view of the pulleys and tension adjustment arrangement, and Figure 8G is an exploded perspective view of one side showing the side extrusion and pulleys. Figure 8H is an end sectional view through the side, and Figure 81 is a perspective view showing the path of a single cord in the dual screen arrangement shown in Figure 8A. In the description that follows the lateral direction is the x direction in Figure 8H, or axial direction of a spindle (width direction), and the vertical direction is the y direction in Figure 8H, (the height or thickness of the frame). Distal directions will typically be distal with respect to a spindle pulley 42 or 72.

[0090] In this embodiment the frame is formed of cover extrusions 11 1, 112, 113, 1 14 which connect at corner extrusions (defining the first end 11, second end 12, first side 13 and second side 14 respectively). For example Figures 8B and 8C show top cover 11 1 connects to top corner 1 15 which in turn connects to second side cover 1 14, which in turn connects to bottom corner 1 16 , which in turn connects to bottom cover 113. The ends of the covers and corners feature matching slots and projections to facilitate assembly. The corners also support internal frame members such as internal top and bottom cross members 128 129 and side extrusions such as second side extrusion 150 shown in detail in Figures 8G and 8H. The side extrusions also support the pulley and tension adjustment arrangements located in frame sides and provide mounting points for the spindles and spindle pulleys. For example as shown in Figure 8A the first side 13 comprises a first pulley and tension adjustment arrangement 103 and the second side comprises a second pulley and tension adjustment arrangement 104 which is substantially identical or a mirror image of the first pulley and tension adjustment arrangement 103. [0091] Figures 8B to 81 show the second pulley and tension adjustment arrangement 104 in more detail. In this embodiment the pulley and tension adjustment is a low profile compact loop arrangement that accommodates the components for operating both the first screen 21 and the second screen 31. The first screen may be a blind and the second screen may be an insect screen or vice versa. The spindles comprise an inner cylindrical recess to retain the inner end of the screen which then wraps around the spindle. The pulley and tension adjustment 104 comprises a first cable 51 that winds off first spindle 41 and is directed to a shuttle pulley 52 (first guide pulley 52) that redirects the cable 51 back to an anchor pulley 53 (second guide pulley 53) located between the shuttle pulley 52 and the spindle 41. The anchor pulley 53 redirects the cable back past the shuttle pulley to a first end guide in the form of a pair of vertically aligned guide pins 59 that redirect the cable 51 to an anchor point 123 on the edge panel 22 of the first screen 21. The end guide, in this embodiment vertically aligned pins 59, are located adjacent the second spindle 72, and past the maximum extended position of the first screen 21. That is, the guide pins 59 are distal of the maximum distal location of the edge of the first screen 22. Similarly a second cable 61 that winds off second spindle 71 is directed to a shuttle pulley 62 (a first guide pulley) that redirects the cable 61 back to an anchor pulley 63 (a second guide pulley) located between the shuttle pulley 62 and the spindle 71 . The anchor pulley 63 redirects the cable 61 back past the shuttle pulley 62 to a second end guide which in this embodiment is a pair of vertically aligned guide pins 69 that redirect the cable 61 to an anchor point on the edge panel 32 of the second screen 31. In this embodiment the tension adjustment is provided by a spring 55 anchored to the two shuttle pulleys 52 and 62. This provides a more compact arrangement than two springs, or two springs on the screen edge panels 22 as shown in the previous embodiment.

[0092] The design of the shuttle pulley guide is shown in Figures 9 A to 9E which are perspective 901 , front 902, top 903, rear 904, and bottom 905 views. The shuttle pulley comprises a body 91 1 which supports a pulley 912 on axis pin 913 at one end of the body and a spring anchor arrangement at the other end of the body comprising a slot 915 though which an anchor pin 914 passes through. The anchor pin 914 axis is orthogonal to the pulley axis pin 913. A support 916 is formed or connected to the base of the body 911 and is formed with a T shaped profile to form two side slots 917 in the base. The design of the anchor pulley guide is shown in Figures 9F to 9J which are perspective 921 , front 922, top 923, rear 924, and bottom 925 views. The anchor pulley comprises a body 931 which supports a pulley 932 on axis pin 933 at one end of the body and a projection arrangement 934 to separate the incoming and outgoing cable (and so protect the pulley and prevent cable fouling). A support 936 is formed or connected to the base of the body 931 and is formed with a T shaped profile to form two side slots 937 in the base. An anchor arrangement 935 such as a rotatable grub screw which can pass through the body 911 and support 936 is also provided to allow the anchor pulley to be fixed (anchored) in a particular location, for example to side member 19 such as extrusion 150. Identical shuttle pulleys and anchor pulleys are used for each path which facilitates manufacturing as each component is reused (ie 4 identical shuttle pulleys and anchor pulleys per frame). In this embodiment both the first and second end guides are a pair of vertically aligned pins, and may comprise grooves to guide the cable. The pins are supported by shaft 168 extending form the corner piece. In other embodiments the end guides could each be single piece or comprise multiple guide surfaces. The T-shaped base of the shuttle pulleys provide a frictional contact surface with the slot walls to assist in smooth movement of the system.

[0093] The location of the anchor pulley 53 63 and path of the shuttle pulleys 52 62 is constrained by side extrusion 150. The extrusion 150 is shown in Figures 8G and 8H and comprises a slotted pulley channel 151 with flanges that are received into the slots 917 937 formed in the bases 916 936 of the anchor and shuttle pulleys. This constrains the anchor and shuttle pulleys to slide along the channel. At a desired location the anchor pulley is anchored by screwing grub screw 935 to the extrusion 150 (base of slotted channel 151). The shuttle pulleys are then able to slide along the channel 151 to adjust tension in the cables during winding and unwinding operations.

[0094] The extrusion 150 also comprises a tab 152 and projection 153 to receive a removable internal cover 160 which hides the pulley and tension adjustment arrangement 104. The removable internal cover 160 has a projection to clip into the tab 152. The extrusion 150 further comprises an upper slot 154 with a vertically descending arm 155 which clips into outer cover 114. Clips 170 are used to clip the outer cover 1 14 to the extrusion 150. The extrusion also comprises cavities 157 and 159 which receive matching projections 167 and 169 from corner pieces 117 and 118. Below the pulley channel 151 a flange projection 156 extends laterally inward (and is aligned with the base of cavity 159). A flange projection 156 and projection forming lower cavity 157 form a guide (ie define a guide slot) for the lateral end pieces 122 of the screen edge panels 22 and 32. Additionally the lower laterally extending member ends in slot 1 58, which together with matching slot 161 formed at the lower end of the internal cover 160, forms an opening through which the end of the screen edge panels 22 and 32 can pass (with lateral end pieces 122 being guided and constrained by the slot formed by flange 156 and cavity projection 157). To protect against ingress of dust, light or insects, brush pieces may be inserted in each side of the slot (161 and 158) which extend to the screen panel 22 (not shown).

[0095] The pulleys in the shuttle pulley and anchor pulleys are aligned (ie in the same plane) and are above flange 156, whereas the pair of guides 59 and 69 are laterally offset with respect to the pulleys (parallel plane) and located past the end of flange projection 156. Thus as shown in Figure 8E, in which the lateral dimension has been significantly expanded (with the original on the left and the expanded version indicated by dotted arrow on the right), the two cables 51 and 61, when travelling from anchor pulley to the pair of guides 59 extend in a lateral direction. As can be seen in Figure 8E, each of the first shuttle pulley, the first anchor pulley, the second shuttle pulley, the second anchor pulley, the first spindle pulley and the second spindle pulley are located in a first plane, and the first end guide and the second end guide are located in a second plane parallel to the first plane and proximal to the screen opening. A third plane comprises a proximal side of the first spindle pulley, a proximal side of the second spindle pulley, a distal side of the first end guide, and a distal side of the second end guide. The lowermost guide in a pair of guides 59 and 69 are located vertically above the screen edge panel so the cable drops slightly as it connects to the screen edge panels.

[0096] In this embodiment each of the pair of guides 59 and 69 are vertically separated cylindrical guides supported by a guide projections 168 in the corner pieces 117 118. For example in this embodiment the guide projections are shafts. As can be seen the cylindrical guides are co-planar and each axis is vertically aligned, and the vertical separation of the pair of vertically separated cylindrical guides is less than or equal to the diameter of the first spindle pulley 42 (and the less than or equal to the diameter of the second spindle pulley 72). As can be seen in Figures 8E and 8H, in this embodiment an uppermost edge of an upper cylindrical guide is vertically above an uppermost edge of the shuttle pulleys, and the lowermost edge of a lower cylindrical guide of a pair of vertically separated cylindrical guides is vertically below a lowermost edge of the shuttle pulleys and above the plane or in the plane of the flange 156. In this embodiment the cylindrical guides are cylinders with central grooves to guide the cable as shown in Figure 8E. In other embodiments other shaped guides including a single vertically extended guide, or guides with internal channels could be used.

[0097] Thus in this embodiment the first operative is connected between the first spindle pulley and the lateral end of the first screen end panel, and follows a path from the first spindle pulley to the first shuttle pulley, from the first shuttle pulley to the first anchor pulley, from the first anchor pulley to the first end guide, and from the first end guide to the lateral end of the first screen, and the first shuttle pulley is distal of the first anchor pulley with respect to the first spindle pulley, and the first end guide is distal of the maximum extended location of the first screen end panel. A similar arrangement is used for the second operative means for the second screen (ie replace first with second in the above description). The elastic member (spring) adjusts the tension in the first operative means as the first screen is wound and unwound from the first spindle, and adjusts the tension in the second operative means as the second screen is wound and unwound from the second spindle.

[0098] This embodiment uses shuttle pulleys which provide some additional friction which provides more consistent tension and assists in holding the screen in place. It also contributes to a smooth and gentle feeling when using the screen system - as in contrast to prior art systems the screen is not being moved against a spindle spring retracting force. Additionally when moving one of the screens, the other screen is effectively fixed in place as the other shuttle acts as an anchor point for the spring ie the friction between the shuttle and the slot acts to clamps the spring in place. However the system allows both screens to be moved at the same time, in which case each opposing shuttle still provides an anchoring point for the spring. This enables either screen to be moved and held in place at any point along the track. Further connecting the spring between two shuttles provides an extremely compact arrangement and reduces the part count. This enables a more compact arrangement than the earlier embodiment with the springs on the screen edge panel 22.

[0099] Additionally the compact paths enable two sets of cables to overlap with minimal interaction or friction. The cables have two contact points where they cross over - the first as they move from anchor pulley to the end guides, and the second as they run from the end guides to the anchor points on the screen edge panel 22. Also the point of contact moves (ie slides distally or proximally towards a spindle) as the screen is moved. Thus the point of contact between cables is not fixed leading to excessive wear. Further, and in each case, the two cables have a low opening angle (ie are almost parallel) so when one cable is moving there is very little force imparted on the other cable reducing any wear. This thus contributes to long life and reduces maintenance. In one embodiment the cables are formed of a strong wear resistant material such as Kevlar.

[00100] In one embodiment the spindle pulley has an outer diameter of 30mm and inner diameter of 21mm, and the anchor and shuttle pulleys have an outer diameter of 14mm and inner diameter of 12mm. The end guides are formed of two cylinders with a 7.6mm outer diameter and 7mm inner diameter. The vertical separation of the centre of the cylinders is 10mm, which with the two radii gives a vertical drop 87 of 17mm for the cables around the end guide. The length and width of the anchor pulley is 18.5mm is 14.2 mm respectively and the length and width of the shuttle pulley is 21 mm and 13.7mm respectively. In one embodiment the two end guides span 248mm and the two spindle pulleys are separated by 294mm. The inner span of the spindle pulley (around which the cable is wrapped) is 6.7mm and the outer span (including side walls) is 8.6mm. The gives a maximum lateral span of the cable 82 of 10mm (ie from distal most inner wall of spindle pulley to proximal most inner wall of cylindrical guide). The lateral width of the cylindrical end pieces is 3.9mm, and thus the total lateral span from the proximal edge of the cylindrical end pieces to the edge of the extrusion (slot) is 18.2mm. In one embodiment the spring is a 25mm spring. In one embodiment, when a screen is fully retracted the distance from the midpoint to the centre of the pulley in the shuttle pulley is 33mm, the distance from the midpoint to the centre of the pulley in the anchor pulley is 80mm, the distance from the midpoint to the centre of the cylinders forming the end pieces is 124mm, and the distance from the midpoint to the centre of the spindle pulley is 147mm. In other embodiments the components can remain the same but the separation distances changed to suit the size requirements of the installation. Further during installation the location of the anchor pulley may be adjusted to find the best operating point for the system (ie smoothest operation). The system is well suited to long window spans (ie long first/top end 11 and second/bottom ends 12).

[00101] In contrast to the previous embodiments, this arrangement forms a more compact low profile tension adjustment arrangement fully housed in the side frame and allows the use of (fully retractable) dual screens and blinds. One issue with the previous embodiment is that when the spring is at full extension it can lead to some resistance. Moving the springs from the end panels 22 and to the shuttle pulleys, and the incorporation of additional friction provided by the shuttle pulleys reduces parts and provides a more compact and smoother operation over the full range than the previous embodiments, This embodiment is thus well suited to windows in caravans and recreational vehicles where space is at a premium. The use of anchor pulleys, anchored into the extrusion, with slideable shuttles connected by spring 55 provides a smooth and compact tension adjustment arrangement. Both screens can be easily extended and retracted by hand, with the tension adjustment compensating for change in cable lengths to ensure smooth and easy operation.

[00102] These embodiments have the advantage of prior art systems in that they do not require a spring loaded spindle (ie no spring within the spindle). This allows the use of a smaller spindle contributing to a low profile system. Further the system is less complex and less prone to failure. The mechanism is gentler and allows use by elderly and can be left down whilst the vehicle is in transit (particularly appealing when traversing deserts and the outback to prevent heating of the caravan during the day). The system can also provide a dual screen arrangement. However in another embodiment only a single screen could be used, and a single cable, shuttle pulley, anchor pulley and pair of guides are used. In this embodiment the elastic member connects the shuttle pulley to a fixed anchor point on the extrusion (eg midpoint of the extrusion). Whilst this embodiment is a single screen system it still retains the compact and low profile advantages of the dual screen system described above.

[00103] In some embodiments the screen support assembly is adapted for insertion and removal from the window frame so that it can be retrofitted to an existing window (eg on a caravan, recreational vehicle or house). This may be achieved in several ways. In one embodiment, the dimensions of the window frame are accurately measured and the screen frame is constructed to closely match these. This allows for slideable insertion and removal of the screen support assembly into and out of the window frame, with the close match of window frame to screen dimensions passively retaining the screen frame in place. In other embodiments, the screen may be adapted for insertion and removal using a mounting arrangement that can be positively engaged to retain the screen frame in place, and disengaged when it is desirable to remove the screen frame. The mounting arrangement comprises one or more mounts or components to firmly mount or fix the screen support assembly in the window frame or window frame housing 2. The use of a mounting arrangement provides greater flexibility, as it allows for greater tolerances during manufacture of the frame and compensation for variations between the actual dimensions of the window frame and the screen frame that can occur for a variety of reasons such as measurement errors, imperfect construction, and deviation from orthogonality, temperature effects, or humidity effects. It may also allow use of the system with standard or nominal window frame sizes, or a range of sizes (ie allowing consumers to measure their windows and select the appropriate screen frame to match).

[00104] In one embodiment the mounting arrangement comprises multiple mounts, such as flanges 91 , that extending from the side of the screen support assembly and fasteners 92 (eg screws, bolts, clips, adhesives, welds, etc) is used to fasten the flanges to corresponding support surfaces or structures on the interior side of the window frame housing 2 (see flanges 4 in Figure 7 A for an example). The support surfaces may be configured to receive the fasteners, or the mounting assembly may be configured to take advantage of suitable structures or surfaces on or in the interior side of the window frame housing 2. In another embodiment, the mounting arrangement is a clipable arrangement comprising a plurality of clips. The side members 13 14 may each comprise an outwardly sprung tabs to positively engage with the window frame and thus to lock the screen frame in place though frictional forces. Removal can be performed by using a screw driver or similar tool to depress one of the tabs. In other embodiments the locations of the tabs could be varied, similarly, other arrangements could be used, for example a set of screwable fasteners such as blunt screws that are accessible from the screen opening, and pass through a threaded portion of the screen frame members to allow screwable engagement (or disengagement) with the window frame members. In some embodiments, the fasteners may be hidden behind a removable cover. In one embodiment, double sided adhesive strips or tape is applied to the portions of the screen support assembly to bond or secure the support frame assembly to the window frame (or vice versa). In another embodiment, the profile of the exterior of the screen support assembly members could be tapered or formed with spring tabs to positively engage with the window frame and thus to lock the screen support assembly in place though frictional forces.

[00105] The screen support assembly will typically be comprised of several components or members which are assembled to form a housing or external cover for internal components of the system. When installed the support assembly members act or provide a rigid structure for mounting of the components of the screen system. The components of the assembly members may be thin sheets or extrusions manufactured from suitable materials such as aluminium alloys, steel alloys, and plastics. The screen support assembly may also include removable covers to hide and protect the working parts (eg roller assembly, guide assembly, operative means and tension adjustment arrangement). In one embodiment the screen support assembly is provided as a complete frame, eg a top member, a bottom member, a first side member and a second side member such as thin elongated panel members formed of Aluminium, steel, metal alloys, or plastic, which are fastened together (eg by welded or brackets and fasteners), or moulded as a unitary plastic frame, to form a rectangular frame dimensioned to fit within the interior of the window frame housing 2. In another embodiment the screen support assembly is provided as a partial frame comprising thin elongated panel side members with the first roller assembly and second roller assembly acting as a top member and a bottom member. In this embodiment the mounting arrangements are located on the side members.

[00106] The guide assembly functions to facilitate easy opening and closing of the screen without significant or discernible inertia when moving the screen. In the embodiments described above the guides are pulleys. In other embodiments, the pulleys could be replaced with semi-circular channels manufactured of low friction materials so that the cord can smoothly run through channel. Other variations and adaptions are also possible. For example more complicated guide assemblies utilising multiple tensioners and multiple double backs could be used, although these are less desirable as they increase the size and profile of the screen support assembly.

[00107] To assist in the opening and closing operation, the side members 13 14 comprise slots 16 or screen guide channels to guide the distal edges of the screen end panels. To facilitate guiding of the screen the ends or slots (or channels) may be moulded or fitted with a slideable insert or one or more rollers or bearings that run along the slot. When fully extended the screen covers the screen opening 15.

[00108] The screens 21 31 may comprise a mesh material, such as plastic or wire mesh material with apertures sized to allow air flow whilst preventing the entry of insects or other matter such as leaves/litter (eg a fly screen mesh). Additionally or alternatively, the screen could be a semi-opaque or opaque material or block-out material to provide privacy or to reduce the amount of light passing through the screen opening, ie for use as a window blind. The screen has a distal edge to which a screen end panel 22 is fixed and this can be pulled away from the spindle using a handle 23 to unwind the screen from the spindle and extend the screen across the screen opening 15. When the screen opening is no longer required to be covered (eg when the window is closed, or additional light is desirable), the screen is retracted by pushing the screen end panel back towards the spindle (ie in this context up). The screen system and apparatus described herein may be used for a range of windows including fixed and sliding windows (vertically or horizontal), and multi-panel sliding windows (with one or more sliding panels), and is particularly suitable for small windows. Additionally, the system could also be used for windows with multiple sliding panels. For example in one embodiment the window is comprised of 4 panels in which the inner 2 slide away from each other to cover each of the outer two panels to define a central opening corresponding to the original location of the inner two windows. In this case, the screen support assembly does not span the full width of the four windows, and instead only needs to be wide enough to span the inner two windows (ie the central opening). When installed, the edges of the screen support assembly are aligned with the inner edges of the first and fourth window panels (ie the boundaries of the first and second panels, and the third and fourth panels, when closed). As would be realised the system can be used for covering any opening including doors.

[00109] It is also to be understood that in the context of this specification, retrofitting refers to the fitting or installation of the screen system into an existing or separate window or door frame which for the sake of convenience we will refer collectively as the frame. This may occur during construction of a building as the frames will be installed first, and then embodiments of the screen system described herein are subsequently fitted to some or all of the frames during the construction phase. This may be immediately after installation of the window frames, for example by the same installer, or at a later time such as days or weeks later, by the same or a different installer. This system could be provided as an optional extra to purchasers of the caravan, and thus only installed on an as required basis (ie where the customer selects the option). Similarly the system could be installed into existing doors or windows in a building during occupancy, ie years after construction. As will become apparent the apparatus is designed to be independent of the window frame, so that it can be installed and maintained separately or independently from the window, and if needed removed independently of the window. That is embodiments of the system described herein are not integral in a frame or built into a frame, but rather the system is designed to be attached (or attachable) to an existing frame. Embodiments of the system may be retrofitted such that they appear seamless or integrated with the frame, when in fact they are separately removable. In addition to retrofitting to existing frames (including during manufacture), it will also be understood that the screen system could be integrated with a window frame. For example the screen support assembly may comprises a frame that also supports a window panel (a fixed panel or slideable panels), and the system would be installed as a single unit during construction of the building or caravan.

[001 10] Embodiments of the system can be retrofitted to a window to replace a permanent insect screen. In this embodiment the permanent insect system can be removed, and an insect screen system could then be attached to the window frame. This allows selective use of the insect screen, for example only when the window is open. In use the screen can be retracted to allow a person an unobstructed view through the window and can also be retracted on demand when greater airflow is desired, or at time of the year when insects are not of concern.

[001 11] The system described herein provides an improved retro fitable arrangement to provide a retractable screen or screens for a moving panel. When the window panel is closed, the screen can be fully retracted so that is does not obstruct the view to any extent. Further the system can be easily retrofitted to a range of existing windows without screens or with permanent screens where a retractable screen is desirable. One advantage of the screen system is that is does not require any form of spring based tensioning arrangements to rewind the screen onto the roller assembly. Instead, the arrangement guides an operative member such as a cord through a compact double back path to a tension adjustment arrangement located behind the screen end panel to provide a compact and smooth mechanism to extend and retract the screen. The tension adj ustment arrangement comprises a spring and removable chain members to allow adjustment of the tension. In an alternative embodiment the arrangement guides the operative members along a looped path around a shuttle pulley and anchor pulley before being directed to the screen end panel via end guides, with a spring connecting the two shuttles to provide a compact and smooth mechanism to extend and retract the screen. When the screen is extended, pushing the distal edge to force retraction of the screen is translated into a pulling action on the cord to unwind the cord off the first pulley, and this drives the rotation of the spindle to wind the screen back on. Conversely, pulling the distal edge to extend the screen rotates the spindle and pulley to wind the cord back onto the first pulley. This guide assembly is relatively compact, allowing the support assembly to have a low thickness/profile so that the support assembly does not extend in from the window frame and unnecessarily obscure the window panel. Further, to improve the smoothness and to provide adjustability, the guide assembly includes a tension adjustment assembly. The guide assembly and tension adjustment assembly are compact and have a low profile making the system suitable for use with windows including small caravan windows. The system is also less complex with fewer parts than existing systems enabling cheaper and more efficient manufacture.

[001 12] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[001 13] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[001 14] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the disclosure as set forth and defined by the following claims.