Abstract
A flexible screen material can be cut out of square, or part of the screen frame can be formed out of square such that when the screen is fitted to the screen frame, there is less sagging.
Claims
1. A window or door opening screen assembly, the assembly comprising: (a) a flexible screen material having opposed side edges and an upper and lower edge, and a multiplicity of longitudinal zones extending between the side edges, (b) a first at least substantially rigid edge member to which one of the opposed side edges of the screen material is attached, (c) a second at least substantially rigid edge member to which the other of the opposed side edges of the screen material is attached, (d) the screen material able to be wound onto and off the second edge member, (e) a tensioner to tension the screen material, and, (f) a tension equalizer to provide substantially equivalent tension to the longitudinal zones, wherein the tension equalizer is formed by making at least one of the opposed side edges of the screen material concave and attaching at least one of the rigid edge members along the concave length of the at least one of the opposed side edges.
2. The assembly of claim 1, wherein the screen material is a mesh and the multiplicity of longitudinal zones comprise longitudinal fibers of the mesh material.
3. The assembly of claim 1, wherein the tensioner comprises at least one spring or other biasing means.
4. The assembly of claim 3, wherein the spring biases the second edge member to adopt rotation about a rotational axis of the edge member.
5. The assembly of claim 4, wherein the spring is associated with the first edge member.
6. The assembly of claim 1, wherein the edge member which attaches to the concave side edge of the screen material is straight.
7. A window or door opening screen assembly, the assembly comprising a flexible screen material having opposed side edges, upper and lower edges and longitudinal zones extending between the opposed side edges, one side edge being attached to a first rigid or substantially rigid edge member, the other side edge being attached to a second rigid or substantially rigid edge member, and a tension equalizer to provide equivalent tension to the longitudinal zones, wherein the tension equalizer is formed by making at least one of the side edges of the screen material concave and attaching at least one of the rigid edge members along the concave length of the at least one side edge the flexible screen material to be wound onto and off at least one of the edge members in an expected manner.
8. The assembly of claim 7, wherein the zones comprise fibers.
9. The assembly of claim 7, wherein the screen material is an insect screen.
10. The assembly of claim 7, wherein the upper and lower edges of the screen material are substantially straight.
11. The assembly of claim 1, wherein the tension equalizer further maintains the upper and lower edges of the screen material in a substantially straight orientation.
12. The assembly of claim 1, wherein tension is maintained in the upper and lower edges of the of the screen material without requiring an edge member attached to the upper and lower edges.
13. The assembly of claim 7, wherein the tension equalizer further maintains the upper and lower edges of the screen material in a substantially straight orientation.
14. The assembly of claim 7, wherein tension is maintained in the upper and lower edges of the of the screen material without requiring an edge member attached to the upper and lower edges.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Embodiments of the invention will be described with reference to the following drawings in which:
(2) FIGS. 1-6 ILLUSTRATE A PARTICULAR NON-LIMITING TYPE OF LARGE SCREEN ASSEMBLY WHERE THE SCREEN MATERIAL CAN BENEFIT FROM THE TENSION EQUALLIZER OF THE PRESENT INVENTION.
(3) FIG. 1. Illustrates an upper portion of the screen assembly particularly illustrating the drum and the screen fully extended.
(4) FIG. 2. Illustrates the view of FIG. 1, with the screen partially extended.
(5) FIG. 3. Illustrates a lower portion of the front edge of the screen and particularly illustrating the third pulley, the fourth pulley and the lower end of the biasing means (the housing being removed on the front edge of the screen for clarity).
(6) FIG. 4. Illustrates an upper portion of the front edge of the screen and particularly illustrating the first return pulley and a second pulley and an upper part of the biasing means which is adjacent the front edge of the screen.
(7) FIG. 5. Illustrates the screen in the retracted position.
(8) FIG. 6. Illustrates the screen in the approximately half extended position.
(9) FIG. 7. Illustrates the “Catenary Effect” on a fibre.
(10) FIG. 8. Illustrates an undesirable sagging effect on the mesh,
(11) FIG. 9. Illustrates an ideal screen assembly where each rigid each member is infinitely stiff and therefore all the longitudinal zones/fibres are horizontal.
(12) FIG. 10. Illustrates (in an exaggerated manner) the reality of a large screen assembly where the edge members deform causing unequal tension (and therefore creation of sagging zones) in the longitudinal fibres.
(13) FIG. 11. Illustrates a solution to the sagging of the screen assembly according to a first embodiment whereby one edge of the screen material is concave to provide the tension equalizer.
(14) FIG. 12. Illustrates a screen assembly using the solution of the first embodiment and illustrating substantially equivalent tension in the longitudinal fibres thereby preventing sagging zones being formed in the screen material.
(15) FIG. 13. Illustrates a solution according to a second embodiment of the invention and where both side edges of the screen material are concave to provide the tension equalizer.
(16) FIGS. 14a-d. Illustrate a solution according to a third embodiment of the invention and wherein one of the edge members provides the tension equalizer.
(17) FIGS. 15-16. Illustrates variations in configuration of the edge member to provide the tension equalizer.
(18) FIG. 17. Illustrates the sagging of the upper horizontal edge and the lower horizontal edge of a screen material (which is undesirable).
(19) FIG. 18. Illustrates a solution to the sagging of the upper horizontal edge and the lower horizontal edge.
(20) FIG. 19. Illustrates a solution to the sagging of the upper horizontal edge and the lower horizontal edge.
(21) FIG. 20. Illustrates a solution to the sagging of the upper horizontal edge and the lower horizontal edge.
(22) FIG. 21. Illustrates the shape of the screen material with no forces applied and providing a solution to the sagging of the upper horizontal edge and the lower horizontal edge.
(23) FIGS. 22-26. Illustrate various other shapes of the screen material.
BEST MODE
(24) Referring to FIGS. 1-6, these figures illustrates an exemplary type of large screen arrangement where the screen material would be otherwise prone to having sag zones if it were not for the benefit of the present invention. The screen assembly according to the particular embodiment basically comprises the following components: A screen 10, which in the particular embodiment comprises an insect screen, a supporting member (the second at least substantially rigid edge member) 11 about which the screen is wound and unwound, a drum 12 which is positioned in an upper part of the assembly and on top of supporting member 11, a front edge 13 of the screen 10 and which is made of an elongate aluminium section (the first at least substantially rigid edge member), a biasing means 14 (the lower portion being visible in FIG. 3, and the upper portion being visible in FIG. 4), the biasing means being attached to front edge 13, a line member which is split into a first line member 15 and a second line member 16 (this will be described in greater detail below), a first return pulley 17 (FIG. 4), a second pulley 18 (FIG. 4), a third return pulley 19 (FIG. 3) and a fourth pulley 20 (FIG. 3).
(25) The screen assembly as illustrated in FIGS. 1-6 does not clearly illustrate the tension equalizer which is better illustrated in the remaining figures.
(26) Screen 10, in the particular embodiment, can extend between 2-5 m and therefore has this length at least. One end of the screen 10 is attached to the supporting member 11. Supporting member 11 is mounted for rotation about its longitudinal axis such that the screen 10 can be wound and unwound from the supporting member. Importantly, as screen 10 is wound or unwound from the supporting member, the diameter (this being the diameter of the supporting member plus (+) any attached screen material) will vary, and will decrease as the screen is unwound and will increase as the screen is wound.
(27) Attached to the top of supporting member 11 is drum 12. In the particular embodiment, drum 12 has a tapered face and is therefore substantially conical. The taper goes from a smaller diameter adjacent the top of the supporting member 11 to a large diameter. It is envisaged that the drum may also be positioned the other way as well. The length of the drum is approximately 3 cm. The widest part of the drum (in the particular embodiment) will be approximately the same diameter as the widest diameter of the supporting member 11 plus (+) screen 10 (that is when the screen is fully wound on the drum and is completely retracted), and the narrowest part of the drum (in the particular embodiment) will be approximately the same diameter of the diameter of the supporting member plus (+) any remaining screen 10 when the screen has been fully extended, and unwound from the drum.
(28) The first line member 15, which in the particular embodiment comprises a plastic coated steel wire having a diameter of between 1-3 mm, has one end attached to the drum. Therefore, rotation of the drum will cause line member 15 to wind on to the drum or off the drum as the case may be. In the particular embodiment, and because of the cone shape of the drum, the line member will be laid next to each other on the drum. Thus, the diameter of the drum at the point where the line member is wound onto or off the drum will vary because of the conical shape of the drum.
(29) The first line member 15 extends from drum 12 and extends about first return pulley 17 and then about second pulley 18 and is ultimately attached to the upper part of the biasing means 14 which in the particular embodiment comprises a spring. Thus, there is tension in the first line member 15. A second line member 16 is also provided which is formed from the same material as first line member and second line member 16 has one end which is joined to first line member (and therefore branches therefrom) in between drum 12 and first return pulley 17. Second line member 16 then also extends about first return pulley 17 but then extends substantially vertically to extend about third pulley 19, then fourth pulley 20 and is attached to the lower end of biasing means 14. Thus, there is tension in second line member 16.
(30) The biasing means 14, and second pulley 18 and third pulley 19 are all attached to or relative to the front edge 13 of the screen and therefore move with the screen.
(31) In use, as the screen is extended, the first line member will be wound about and onto drum 12. In the particular embodiment, as the line winds onto the drum the line progressively winds from the larger diameter of the drum to the narrower diameter of the drum and therefore the diameter reduces where the line is wound onto the drum. This can be seen with reference to FIG. 1 and FIG. 2. At the same time, the diameter of the support member 11 containing the wound up screen material 10 will decrease as the screen material is unwound, and the construction and arrangement is such that the diameter of the drum is about the same at any one point as the diameter of the support member plus (+) any remaining screen material. This will also be the case when the screen is retracted as this will cause the diameter of the support member plus (+) screen material to increase and at the same time the line member is being unwound from the drum at progressively increasing diameters.
(32) A disadvantage with the above type of screen assembly (and other larger screen assemblies) is that even though tension is used (e.g. spring) to tension the screen material, the material still sags under gravity because of the Catenary effect which has been described previously and which is illustrated in FIG. 7 and FIG. 8. This results in the screen mesh not looking attractive and having “sag zones” in the screen mesh. The effect comes about because the rigid edge members are not infinitely stiff and instead do deflect or deform slightly during use. This causes unequal tension in the longitudinal zones/fibres of the screen mesh and this, in turn, causes the sag zones to appear which is not desirable.
(33) The term “zones” is meant to encompass a screen that is not woven and therefore does not contain easily identifiable longitudinal fibres. This type of screen may comprise a plastic sheet and the “longitudinal zones” in the plastic sheet will comprise “imaginary” thin bands/strips extending from one edge to the other edge. A screen comprising a plastic sheet which has some stretch, will benefit from the tension equalizer according to the present invention.
(34) FIG. 9 illustrates schematically an ideal (but not possible) screen assembly where the edge members 25, 26 are infinitely stiff and therefore the longitudinal fibres 27 in the screen material are all horizontal.
(35) FIG. 10 illustrates schematically the realistic situation in a screen assembly where the edge members 25, 26 deform inwardly slightly (in FIG. 10 the deformation is exaggerated), and the results is that the tension 28 is unequal in the various longitudinal fibres in the screen material resulting in sag zones. Specifically, the tension in the middle longitudinal fibres is less than the tension in the longitudinal fibres which are in an upper area and lower area of the screen material.
(36) FIG. 11 and FIG. 12 illustrate a tension equalizer according to a first embodiment of the invention to provide substantially equivalent tension in the longitudinal fibres of the screen material. Referring initially to FIG. 11, the screen material (fabric) 10 has one vertical side edge 29 cut with a curve such that the middle longitudinal fibres are shorter than the fibres in the upper area and a lower area of the screen material. Each edge member 25, 26 is substantially straight.
(37) When the screen material (fabric) is attached to each edge member, the curvature of side edge 29 accommodates the deforming of the edge members 25, 26 such that the tension (illustrated by arrows 30) in the longitudinal fibres is approximately the same. It will be appreciated that in this and other embodiments following, that the screen material may simply be attached to the edge member in a way which follows the desired shape without actually being cut thus.
(38) This is illustrated in FIG. 12.
(39) FIG. 13 illustrates a tension equalizer according to a second embodiment of the invention. In this embodiment, each side edge of the screen material 10 is cut with a curve (29, 31) such that subsequent attachment to the edge members 25, 26 will result in substantial equivalent tension in each of the longitudinal fibres of the screen material.
(40) FIG. 14a-d illustrates a third embodiment of the invention. In this embodiment, the tension equalizer is provided by a specially designed edge member and the screen fabric does not need to be cut into a curve. Specifically, the figures illustrates a rectangular piece of fabric 10 to which are attached two edge members 32, 33 which are roughly parallel to each other. To one edge member 32 is provided a second stiffer edge member 34. A restraining force is then applied to the ends of the edge members and both edge members deflect due to the tension from the fabric. An adjusting means is provided which can comprise shims, adjusting screws or the like to deform edge member 32 to compensate for the deflection and therefore restoring equal tension in the longitudinal fibres.
(41) FIG. 14(b) illustrates the edge members 32, 33 attached to the screen 10 but where no tension has yet been applied. FIG. 14(c) illustrates tension applied to the screen and showing the unequal tension (arrows 30) in the longitudinal fibres and illustrates the additional stiffer edge member 34 attached but not yet adjusted. FIG. 14(d) illustrates how the edge member 32 can be deformed the other way by the use of adjusting screws (or something else) between the edge member 32 and the stiffer edge member 34, and in doing so, results in the creation of substantially equivalent tension in the longitudinal fibres in the screen material 10.
(42) FIG. 15 and FIG. 16 illustrates another embodiment of the invention which can comprise a system where the fabric (screen material 10) is used as a movable screen or blind and where it is desirable for at least one edge member to have a substantially straight edge so that it can align with a second screen or blind or with the edge of a window or door opening (for example). Achieving the straight edge can be achieved by curving or otherwise shaping one edge member (36) such that when the edge member is attached to the screen material and tension load from the fabric is applied to the edge member, the edge member is largely restored to a straight condition (see FIG. 16). The edge member may have the configuration illustrated as reference numeral 36 but may also have different configurations (e.g. 37, 38).
(43) FIGS. 17-26 illustrate various ways to keep the top edge and the bottom edge of the mesh material (fabric) substantially straight. It is highly desirable that the top edge and the bottom edge are substantially straight and do not sag as illustrated in FIG. 17. It is found that if the fabric is longer than 1.5 m, the sagging in the top and bottom edges becomes quite significant. This can result in several disadvantages. One disadvantage is that the fabric may not properly wind onto or off the vertical rod to which the fabric is attached. Another disadvantage is that the upper edge in the lower edge of the fabric is typically hidden by a top channel and bottom channel. Although the fabric is not attached to the channel (if it were, the fabric could not be attached to a roll), the top edge is hidden from view by passing into and moving along the top channel and the bottom edge is hidden from view by passing into and moving along the bottom channel. If the bottom edge of the screen sags, it can drag in the bottom channel and become damaged. If the top edge of the screen droops too much it can leave the top channel and there will be gap between the top edge of the screen and the top channel which is unsightly and in the case of an insect screen, would allow insects to pass through the gap etc.
(44) Therefore, there would be an advantage if it were possible to provide a screen material which, in use, would have a substantially straight top edge and a substantially straight bottom edge. There would be a particular advantage if the screen assembly as described above (having the tension equaliser) also has a substantially straight top edge and a substantially straight bottom edge.
(45) FIG. 18 illustrates a first embodiment which enables the top and bottom edges of the screen material to be straight in the unfurled (rolled up) position, thereby allowing the screen material to roll up in a predictable manner onto the vertical rod member. This would make management of the top and bottom edges of the fabric much more simple. In the embodiment of FIG. 18, this is achieved by cutting the screen material near the top and the bottom and typically for a distance of up to 50 mm or so and because this small amount of screen material is light, the screen material has enough integral stiffness to hold its flatness in these areas. The screen material can be cut to match the Catenary effect in the screen material so that the screen material will always have top and bottom edges at the same position and the screen material will roll up very neatly on the rod member.
(46) FIG. 19 illustrates one method to enable the screen material to be pre-cut prior to use. The method requires the screen material 10 to be supported vertically with even tension (see arrows 30) applied to the side edges, the tension closely matching the tension load that will be used in practice. This effectively replicates how the screen material will be installed. Once supported vertically, and with the tension adjusted, the top and bottom edges of the fabric can be trimmed off to be straight. Cut lines 40 illustrate this.
(47) FIG. 20 illustrates an alternative embodiment of the invention. In this method, the mesh material is positioned in the vertical plane so that gravity acts on the screen fabric. This (fabric) 10 is then rolled up on a rod member (second rigid end member 25) while still under tension and then to cut through both the mesh material 10 and the rod member 25. When reinstalled with the edge member is under tension, the top and bottom edges of the mesh material will be straight. Cut lines 41 illustrate this. It will be appreciated that in possible variation of this method, the rod member itself is not cut through.
(48) When the mesh material is cut according to the alternative embodiment illustrated in FIG. 20, and if the mesh material was laid flat with no forces applied to the mesh material, the shape of the mesh material would be as illustrated in FIG. 21. The fibres of the mesh material will be straight and the top and bottom edges will be curved.
(49) Therefore, rather than using the alternative embodiment illustrated in FIG. 20, it is also possible to pre-cut the mesh material into the desired shape before the mesh material has any forces applied to it. Thus, it is possible to pre-cut the mesh material to the shape illustrated in 21 prior to assembling the screen assembly, and FIG. 22 and FIG. 23 illustrate variations to the shape of the mesh material.
(50) FIGS. 24 and FIG. 25 illustrate an alternative method to precut the mesh material prior to assembling the screen assembly. In this alternative method, the mesh material can be attached to each members (not illustrated) and can be pulled in the direction of the arrow in FIG. 24 and FIG. 25 to approximate the shape that gravity will cause the mesh material to take when in the vertical plane. Simple straight cuts (see cut lines 42 and 43) can then be made at the top and the bottom of the mesh material to create a shape in the top and the bottom edges.
(51) Referring to FIG. 26, it is also possible to attach the mesh material 10 to a rod member 25, then to pull the mesh material as illustrated to create an approximate desired shape, then to roll the mesh material onto the rod member 25 while still under tension and then to cut through both the mesh material and the rod member (or just the mesh material) while the fabric is wound about the rod member (see cut lines 44). It is also possible to cut the fabric with a pair of stationery blades as the fabric is being wound up onto the rod member.
(52) Throughout the specification and the claims (if present), unless the context requires otherwise, the term “comprise”, or variations such as “comprises” or “comprising”, will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.
(53) Throughout the specification and claims (if present), unless the context requires otherwise, the term “substantially” or “about” will be understood to not be limited to the value for the range qualified by the terms.
(54) It should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.
