Screen Tensioning Mechanism And System

Abstract

A screen tensioning mechanism for use in a retractable blind, said screen tensioning mechanism comprising: (a) a projecting member having a head portion and a resiliently deformable tail portion; and (b) a housing member comprising: (i) a first opening adapted to receive an end of a support rod; and (ii) a second opening having a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Australian provisional patent application number 2010 904052 filed on Sep. 9, 2010, and titled SCREEN TENSIONING MECHANISM AND SYSTEM, which is incorporated herein by reference.

TECHNICAL FIELD

[0002] This invention relates generally to a screen tensioning system and, in particular, to a screen tensioning mechanism for use in retractable blinds. The invention is particularly useful in relation to Roman blinds that are predominantly constructed from fabric however, it should be understood that the invention is intended for broader application and use.

BACKGROUND

[0003] The functional and decorative use of blinds, and particularly Roman blinds, dates back over two thousand years to times when glass windows were not available for architectural applications. In modern times, the use of blinds and window coverings in residential and commercial settings has become commonplace.

[0004] Roman blinds are predominantly constructed using a soft fabric material which gathers into pleats as the blind is raised. A cord is generally connected to dowel rods or slats that are attached to, or within, the fabric material to facilitate the pleating of the fabric as the blind is raised, and the straightening of the fabric as the blind is lowered. In the modern construction of Roman blinds, and particularly those blinds incorporating a soft fabric material, it has become common to use horizontally oriented dowel rods or slats throughout the fabric to create the desirable regular pleats as the blind is raised. However, the use of support members such as dowel rods and slats is often ineffective in producing the required degree of tension in the fabric, and irregular pleating, or even creasing, of the fabric results. Such undesirable results often become more prominent after repeated operation of the blind.

[0005] In view of these limitations, there is a need for a screen tensioning mechanism and system for a retractable blind that can maintain the requisite degree of horizontal tension in a screen, which in turn will facilitate the proper pleating and straightening operations of the blind.

[0006] In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of the common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY

[0007] According to an aspect of the present invention, there is provided a screen tensioning mechanism for use in a retractable blind, said screen tensioning mechanism comprising:

[0008] (a) a projecting member having a head portion and a resiliently deformable tail portion; and

[0009] (b) a housing member comprising: [0010] (i) a first opening adapted to receive an end of a support rod; and [0011] (ii) a second opening having a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, [0012] wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

[0013] The head portion and tail portion may be integrally formed. Alternatively, the tail portion may be releasably attached to the head portion. In addition, the tail portion may comprise a length of resiliently deformable material such as, for example, strip steel.

[0014] The tail portion preferably comprises at least two legs extending from the head portion, and these legs may diverge from one another as they extend from the head portion. In one embodiment of the invention, two legs extend from the head portion and each incorporate an initial straight portion followed by a gradual curve as the legs diverge. The divergence of the legs, created by the curved portions, improves the biasing of the projecting member by allowing for earlier engagement of the legs with the tapered internal profile of the second opening. The head portion and the legs may be integrally formed. Through the use of modern manufacturing techniques such as the injection moulding of plastics, it may be advantageous if at least the projecting member could be formed as single piece.

[0015] The tapered internal profile preferably comprises a first pair of opposing internal surfaces which, in use, engage and inwardly displace the legs. This first pair of opposing internal surfaces may converge toward one another, and may also have a predefined angular separation. This predefined angular separation may fall substantially in the range from 5 degrees to 25 degrees. In a particularly preferred embodiment of the invention, the predefined angular separation may be approximately 10 degrees, or approximately 14 degrees. By increasing the predefined angular separation of the opposing internal surfaces, it is possible to increase the biasing force that is applied to the projecting member. Depending on the dimensions of the blind and/or the weight of the screen material used, it may be advantageous to increase the biasing force applied to the projecting member which, in turn, would increase the tensioning force that can be applied to the screen.

[0016] In a representative embodiment of the invention, the tapered internal profile may comprise a second pair of opposing internal surfaces having a predefined angular separation that is different from the first pair of opposing internal surfaces. Advantageously, the tail portion of the projecting member can be forcibly received by the second opening in either a light tension orientation or a heavy tension orientation. The light and heavy tension orientations correspond to the engagement of the legs with either the first pair of opposing surfaces or the second pair of opposing surfaces. As the predefined angular separation of the first pair of opposing surfaces and second pair of opposing surfaces is different, one of these pairs will provide less biasing force to the projecting member, and thus a lesser tensioning force to the screen.

[0017] The second opening may further comprise a guide means which in use restricts rotational movement of said projecting member. This guide means may comprise one or more U-shaped grooves which slidably receive at least one of said legs. In one embodiment of the invention, the guide means may comprise two pairs of opposing U-shaped grooves (i.e. on opposing sides of the second opening) which facilitate the insertion of the tail portion of the projecting member in either a light tension or heavy tension orientation. The positioning of the U-shaped grooves about one or more of the legs advantageously prevents rotation of the projecting member and thereby ensures that the legs remain engaged with (or at least in slideable orientation with) either the first pair of opposing surfaces or the second pair of opposing surfaces.

[0018] At least one of said legs may comprise a protrusion on an outer surface that is engageable with the housing member to prevent the tail portion from being ejected from the housing member.

[0019] In an alternative embodiment, the guide means may comprise at least one longitudinal slot which slidably receives a protrusion on an outer surface of the projecting member. In accordance with this embodiment of the invention, the guide means may comprise a pair of opposing longitudinal slots (i.e. on opposing sides of the second opening) which slidably receive a corresponding pair of protrusions on opposing outer surfaces of the projecting member. Each of the protrusions is engageable with a respective one of the slots to prevent the projecting member from being ejected from the housing member. The positioning of the protrusions within the slots advantageously prevents rotation of the projecting member and thereby ensures that the legs remain engaged with (or at least in slideable orientation with) either the first pair of opposing surfaces or the second pair of opposing surfaces.

[0020] Furthermore, the second opening may comprise an internal lip that is engageable with the projecting member to prevent the tail portion from being ejected from the housing member. Advantageously, the frictional engagement between the protrusion on the outer surface of the leg and the internal lip on the second opening is sufficient to prevent the tail portion from being ejected, or simply falling free from, the housing member.

[0021] According to a further aspect of the present invention, there is provided a screen tensioning system for use in a retractable blind, said screen tensioning system comprising: [0022] (a) a support rod for insertion into a pocket of a retractable screen; and [0023] (b) a pair of tensioning mechanisms according to the first aspect of the invention, said pair of tensioning mechanisms being positioned at opposing ends of said support rod, [0024] wherein in use, said head portion of each of said pair of tensioning mechanisms delivers an opposing tensioning force to said pocket of said retractable screen.

[0025] Preferably, the head portion of each of said pair of tensioning mechanisms delivers an opposing tensioning force to an internal side wall of the pocket. The screen tensioning system may be provided in a pocket of the screen which has at least two side walls to secure the support rod and pair of tensioning mechanisms. The size and length of the support rod are preferably selected in accordance with the weight and width of the screen. In use, the head portions of the pair of tensioning mechanisms are biased axially outward from the support rod in opposing directions. Advantageously, and due to the positioning of the support rod between the pair of tensioning mechanisms, this creates a certain degree of horizontal tension in the screen which facilitates the proper pleating operation of the screen. The screen is preferably constructed from fabric, and more preferably a soft fabric material which has a tendency to form soft pleats as the screen is raised.

[0026] According to a still further aspect of the present invention, there is provided a screen tensioning system for use in a retractable blind, said screen tensioning system comprising: [0027] (a) a projecting member having a head portion and a resiliently deformable tail portion; and [0028] (b) a support rod comprising a housing member, said housing member having an opening with a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, [0029] wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

[0030] The housing member may be a separate unit having an end that is adapted to be received in an opening in the support rod. Alternatively, the support rod and the housing member may be integrally formed. In this embodiment of the invention, it is desirable that the tapered internal profile of the housing member is formed during the manufacture of the support rod.

[0031] According to a still further aspect of the present invention, there is provided a screen tensioning mechanism for use in a retractable blind, said screen tensioning mechanism comprising: [0032] (a) a projecting member having a head portion and a resiliently deformable tail portion; and [0033] (b) a housing member comprising: [0034] (i) an end adapted to be inserted into an opening of a support rod; and [0035] (ii) an opening having a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, [0036] wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

[0037] The end of the housing member may be adapted to be inserted into an opening of the support rod such that, in use, the housing member is substantially contained within the support rod.

[0038] According to a still further aspect of the present invention, there is provided a support rod for a screen tensioning mechanism comprising a housing member, said housing member having an opening with a tapered internal profile,

[0039] wherein said opening is adapted to forcibly receive a resiliently deformable tail portion of a projecting member to bias said projecting member axially outward from said support rod.

[0040] According to a still further aspect of the present invention, there is provided a projecting member for a screen tensioning mechanism comprising: [0041] (a) a head portion; and [0042] (b) a resiliently deformable tail portion, [0043] wherein said tail portion is adapted to be inserted into an opening in a housing member of a support rod to bias said projecting member axially outward from said support rod.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Representative embodiments of the present invention will now be described with reference to the accompanying drawings. These embodiments are given by way of illustration only and other embodiments of the invention are possible. Consequently, the particularity of the accompanying drawings are not to be understood as superseding the generality of the preceding description. In the drawings:

[0045] FIG. 1A is a front perspective view line drawing of a screen tensioning mechanism according to a representative embodiment of the present invention. FIG. 1B is a rear perspective view line drawing of the screen tensioning mechanism of FIG. 1A.

[0046] FIG. 2A is a front perspective view line drawing of the screen tensioning mechanism of FIG. 1A with the projecting member in a light tension orientation. FIG. 2B is a front perspective view line drawing of the screen tensioning mechanism of FIG. 1A with the projecting member in a heavy tension orientation.

[0047] FIG. 3A is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 1A with the projecting member in a light tension orientation. FIG. 3B is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 1A with the projecting member in a heavy tension orientation. FIG. 3C is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 1A with the projecting member in an operating position.

[0048] FIG. 4A is perspective view line drawing of a screen tensioning mechanism according to a further embodiment of the present invention. FIG. 4B is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 4A.

[0049] FIG. 5A is perspective view line drawing of a screen tensioning mechanism according to a further embodiment of the present invention. FIG. 5B is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 5A.

[0050] FIG. 6A is perspective view line drawing of a screen tensioning mechanism according to a further embodiment of the present invention. FIG. 6B is a rear perspective view line drawing of the screen tensioning mechanism of FIG. 6A.

[0051] FIG. 7A is a front perspective view line drawing of the screen tensioning mechanism of FIG. 6A with the projecting member in a first tension orientation. FIG. 7B is a rear perspective view line drawing of the screen tensioning mechanism of FIG. 6B with the projecting member in a first tension orientation.

[0052] FIG. 8A is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 6A. FIG. 8B is a cross-sectional side view line drawing of the screen tensioning mechanism of FIG. 6A with the projecting member in an operating position.

DETAILED DESCRIPTION OF THE REPRESENTATIVE EMBODIMENTS

[0053] Embodiments of the screen tensioning mechanism and system will now be described with reference to the accompanying drawings. The invention is particularly useful in relation to Roman blinds that are predominantly constructed from fabric and it will therefore be convenient to describe the invention in that environment. However, it should be understood that the invention is intended for broader application and use.

[0054] Referring to the drawings, FIGS. 1A and 1B illustrate a screen tensioning mechanism 100 in accordance with a representative embodiment of the present invention. The screen tensioning mechanism 100 comprises a projecting member 102 having a head portion 104 and a resiliently deformable tail portion 106. The head portion 104 has a rounded end to facilitate the efficient operation of the mechanism 100 within a fabric pocket of a Roman blind. Since the mechanism 100, and specifically the head portion 104, is designed to deliver a tensioning force to the screen of the blind, the rounded end of the head portion 104 gives the blind an aesthetically pleasing appearance when in use. Furthermore, the rounded end of the head portion 104 minimises the likelihood of the fabric pocket becoming ripped as a result of the tensioning force.

[0055] The tail portion 106 includes two resiliently deformable legs 108 that extend from the head portion 104. In the initial extension from the head portion 104, the legs 108 remain substantially straight and parallel. The legs 108 then curve outwardly from one another, although the divergence between the legs 108 is substantially planar. In a particularly preferred embodiment of the invention, the legs 108 are joined (as shown in the drawings) at a point where the curvature begins. Advantageously, this join between the legs 108 provides additional structural support and limits the range of deformation of the legs 108.

[0056] The head portion 104 and the tail portion 106 are integrally formed and are preferably manufactured from a plastic material using injection moulding techniques. The flexibility of the plastic material allows the legs 108 to be resiliently deformable, although an alternative material with similar physical properties could also be used for the construction of the projecting member 102.

[0057] The mechanism 100 also comprises a housing member 110 that includes a first opening 114 and a second opening 112. The first opening 114 is adapted to receive an end of a support rod (not shown). In this particular embodiment of the invention, the first opening 114 is adapted to receive a circular support rod, although it should be understood that other shapes for the support rod could be used with suitable adaptations of the first opening 114. The embodiments of the present invention envisage various sizes of housing member 110, and particularly the first opening 114, to accommodate support rods having 6 mm and 8 mm diameters. However, it should be understood that alternative sizes would also be suitable. The support rod is preferably constructed from a light-weight metal, plastic or wooden material, which is able to provide the screen with a high degree of horizontal rigidity when the tensioning mechanism is in use. The housing member 110, as with the projecting member 102, is preferably manufactured from a plastic material using injection moulding techniques.

[0058] In an alternate embodiment of the present invention, the housing member 110 may have an end (not shown) that is adapted to be inserted into an opening of a support rod. This would allow for a substantial portion, if not all, of the housing member 110 to be contained within the support rod during use. In an embodiment of the present invention, the support rod may be hollow cylinder made from a light-weight metal or plastic material. It is envisaged that the housing member 110 could be inserted into an end of a hollow support rod, and retained in that position by some mechanical engagement with the support rod, such as by frictional engagement or by means of a lip on the housing member.

[0059] In a further alternate embodiment of the present invention, the housing member 110 may be integrally formed with the support rod. In this case, the tapered internal profile of the housing member 110 is preferably formed in one or more ends of the support rod during the manufacture of the support rod.

[0060] The second opening 112 of the housing member 110 has a tapered internal profile that is adapted to forcibly receive and inwardly displace the resiliently deformable legs 108 of the tail portion 106. The insertion of the tail portion 106 within the second opening 112 of the housing member 110, as illustrated in FIGS. 2A and 2B of the drawings, requires the application of force by the user. As the tail portion 106, and particularly the legs 108, are slidably inserted into the second opening 112, the legs 108 will engage with the tapered internal profile of the housing member 110. This tapered internal profile consists of a first pair of opposing internal surfaces 116 and a second pair of opposing internal surface 118. Each of the first and second pairs of opposing internal surfaces 116 and 118, converge toward one another and have a different predetermined angular separation. As the user continues to apply force to the projecting member 102, the engagement of the resiliently deformable legs 108 with either the first pair of opposing internal surfaces 116 or second pair of opposing internal surfaces 118 causes the legs 108 to flex and become inwardly displaced as the tail portion 106 is further inserted into the housing member 110.

[0061] While the legs 108 are inwardly displaced, by either the first pair of opposing internal surfaces 116 of the second pair of opposing internal surface 118, the resilience of the legs 108 biases the projecting member 102 axially outward from the support rod. It is this bias which allows the head portion 104 to deliver a tensioning force to the fabric pocket of the screen.

[0062] The first pair of opposing internal surfaces 116 has a predefined angular separation of approximately 10 degrees, and the second pair of opposing internal surfaces 118 has a predefined angular separation of approximately 14 degrees. The greater the angular separation of the opposing internal surfaces, the greater the force required to insert and deflect the legs 108 within the housing member 110. Therefore, it follows that if more force is required to insert the tail portion 106, then a greater bias will subsequently be delivered to the head portion 104 of the projecting member 102. Thus, the housing member 110 allows for two different orientations of the projecting member 102. When the projecting member is inserted in a light tension orientation, as shown in FIGS. 2A and 3A, the legs 108 will engage with the first pair of opposing internal surfaces 116. By contrast, when the projecting member 102 is inserted in a heavy tension orientation, as shown in FIGS. 2B and 3B, the legs 108 will engage with the second pair of opposing internal surfaces 118. The orientation of the projecting member 102 can be selected by the user depending on the requirements (e.g. dimensions and weight of the screen) of the particular application.

[0063] To facilitate the positioning of the projecting member 102 in either the light tension orientation or heavy tension orientation, the second opening 112 also includes two pairs of opposing U-shaped grooves 120. Each of these pairs of grooves 120 aligns with one of the first pair of opposing internal surfaces 116 or the second pair of opposing internal surfaces 118. The grooves 120 slidably receive the legs 108 of the projecting member 102, as it is inserted into the housing member 110, and substantially prevent rotation of the projecting member 102 during use. By preventing rotation of the projecting member 102 it possible to maintain a constant bias, and thus tensioning force, by ensuring that the projecting member 102 remains in either the light tension orientation or the heavy tension orientation.

[0064] It will be possible for a user to force the tail portion 106 into the housing member 110 until the point at which the distal ends of the legs 108 engage with an internal wall 140 of the housing member 110, or until the head portion 104 engages with, and abuts, the housing member 110. As the insertion force is withdrawn by the user, the bias applied to the projecting member 102 will cause the projecting member 102 to withdraw from the housing member 110 as shown by the arrow in FIG. 3C of the drawings. This movement or ejection of the projecting member 102 from the housing member 110 will continue until such time as the legs 108 are no longer being deflected by the opposing internal surfaces.

[0065] In order to prevent the projecting member 102 from becoming ejected from the housing member 110, the mechanism 100 comprises a protrusion 130 on the outer surface of each of the legs 108 and a corresponding internal lip 132 on the second opening 112 of the housing member 110. The flexibility of the plastic material, from which the projecting member 102 is manufactured, allows the projecting member 102 to be pushed through this internal lip 132 as it is inserted into the housing member 110. The frictional engagement of the protrusion 130 and the internal lip 132 prevents the projecting member 102 from being released from the housing member 110, and assists the user with the installation process. In an alternative embodiment of the present invention, the retention of the projecting member 102 within the housing member 110 may be secured by more a more rigid structure (such as through the use of different materials to manufacture the components) which would prevent removal of the projecting member 102 from the housing member 110.

[0066] The present invention is also embodied in screen tensioning system which includes a suitable support rod, and a pair of screen tensioning mechanisms as described above in relation to FIGS. 1A to 3B of the drawings. In such a screen tensioning system, a screen tensioning mechanism 100 is positioned at either end of the support rod by inserting the respective ends of the support rod into the second opening 114 of each of mechanisms 100. The specific length of the support rod will be determined by the width of the blind, although this length should be less than the width of the screen to accommodate the positioning of the mechanisms 100 at either or both ends of the support rod.

[0067] The screen tensioning system, incorporating the support rod and the mechanisms 100, can then be inserted into a horizontal fabric pocket of the screen by applying a force to one or more of the projecting members 102 to reduce the overall length of the system. Once the system has been inserted into the fabric pocket, in an appropriate position, the force applied to the projecting members 102 by the user can then be withdrawn. As this force is withdrawn, the biasing force applied to the projecting members 102 of the mechanisms 100 causes the assembly to increase in length. Preferably, the system will continue to increase in length until the head portions 104 of the mechanisms 100 engage with the side walls of the fabric pocket. At such time, the system will be delivering a horizontal tensioning force across the pocket, and therefore across the screen. By maintaining this horizontal tensioning force, it is possible to ensure the correct pleating and straightening operations of the retractable Roman blind as the screen is raised and lowered respectively. More specifically, the rigidity created by this tensioning force substantially prevents irregular pleating or creasing of the soft fabric material.

[0068] FIGS. 4A and 4B illustrate a screen tensioning mechanism 200 according to an alternative embodiment of the present invention. The screen tensioning mechanism 200 incorporates similar structures to those described above in relation to FIGS. 1A to 3B of the drawings. More particularly, the mechanism 200 comprises a projecting member 202 which has a head portion 204 and a tail portion 206. The tail portion 206 includes two resiliently deformable legs 208 which extend from the head portion 204 and remain substantially parallel to one another. The mechanism 200 also comprises a housing member 210 which includes a first opening 214 and a second opening 212. The first opening 214 is adapted to receive an end of a support rod (not shown). The second opening 212 has a tapered internal profile which is adapted to forcibly receive and inwardly displace the legs 208 of the projecting member 202.

[0069] The tapered internal profile of the housing member 210 incorporates a helical configuration. When the projecting member 202 is slidably inserted into the housing member 210, the legs 208 engage with internal helical surfaces 216 of the housing member 210. As more force is applied to the projecting member 202 by the user, the resiliently deformable legs 208 are caused to inwardly deflect and twist as they slidably engage with the helical surfaces 216. The projecting member 202 also includes a pair of ridges 230 along a section of the tail portion 206. These ridges 230 engage with corresponding channels (not shown) in the internal surface of the housing member 210, and substantially prevent rotation of the projecting member 202.

[0070] As the force applied to the projecting member 202 by the user is withdrawn, the resilience of the legs 208 applies a bias to the projecting member 202 which allows the head portion 204 to deliver a tensioning force within the fabric pocket of a screen.

[0071] FIGS. 5A and 5B illustrate a screen tensioning mechanism 300 according to an alternative embodiment of the present invention. The screen tensioning mechanism 300 incorporates similar structures to those described above in relation to FIGS. 1A to 3B of the drawings. The mechanism 300 comprises a projecting member 302 which has a head portion 304 and a tail portion 306. The tail portion 306 includes two resiliently deformable legs 308 which extend from the head portion 304. The legs 308 are positioned offset from one another to facilitate unobstructed movement (by forced deflection) of the legs 208 during use. The mechanism 300 also comprises a housing member 310 which includes a first opening 314 and a second opening 312. The first opening 314 is adapted to receive an end of a support rod (not shown). The second opening 312 has a tapered internal profile which is adapted to forcibly receive and inwardly displace the legs 308 of the projecting member 302.

[0072] The tapered internal profile of the housing member 310 incorporates two angled internal surfaces 316 which are positioned in opposing configurations. When the projecting member 302 is slidably inserted into the housing member 310, each of the legs 308 engages with one of the angled internal surfaces 316 of the housing member 310. As more force is applied to the projecting member 302 by the user, the resiliently deformable legs 308 are caused to inwardly deflect as they slidably engage with the angled internal surfaces 316. Due to the configuration of the angled internal surfaces 316, the legs 308 are deflected inwardly toward one another although, due to their offset positioning, contact between the legs 308 is avoided. The projecting member 302 also includes a pair of ridges (not shown) along a section of the tail portion 306. These ridges engage with corresponding channels (not shown) in the internal surface of the housing member 310, and substantially prevent rotation of the projecting member 302. As the force applied to the projecting member 302 by the user is withdrawn, the resilience of the legs 308 applies a bias to the projecting member 302 which allows the head portion 304 to deliver a tensioning force within the fabric pocket of a screen.

[0073] FIGS. 6A and 6B illustrate a screen tensioning mechanism 400 according to an alternative embodiment of the present invention. The screen tensioning mechanism 400 incorporates similar structures to those described above in relation to FIGS. 1A to 3B of the drawings. More particularly, the mechanism 400 comprises a projecting member 402 having a head portion 404 and a resiliently deformable tail portion 406. The head portion 404 has a rounded end to facilitate the efficient operation of the mechanism 400 within a fabric pocket of a Roman blind. A cross-sectional view of the mechanism 400 shown in FIGS. 6A and 6B is illustrated in FIGS. 8A and 8B. Since the mechanism 400, and specifically the head portion 404, is designed to deliver a tensioning force to the screen of the blind, the rounded end of the head portion 404 gives the blind an aesthetically pleasing appearance when in use. Furthermore, the rounded end of the head portion 404 minimises the likelihood of the fabric pocket becoming ripped as a result of the tensioning force.

[0074] The tail portion 406 is formed from a length of resiliently deformable material such as, for example, strip steel, and includes two resiliently deformable legs 408. The tail portion 406 is releasably attached to the head portion 404 by means of an attachment portion 420. The attachment portion 420 is adapted to loop around a support member 422 at the base of the head portion 404. In order to attach the tail portion 406 to the head portion 404, the legs 408 of the tail portion 406 are drawn together (by application of force by a user) to allow the attachment portion 420 to be placed over the support member 422. The portion of the legs 408 closest to the attachment portion 420 passes through an opening 424 in a side surface of the head portion 404. Once the attachment portion 420 is in position on the support member 422, the force applied to the legs 408 can be withdrawn such that the resilience of the material causes the legs 408 to separate. The tail portion 406 is held in position on the head portion 404 due to the abutment of the legs 408 against retaining projections 426 on the opening 424, which prevent the attachment portion 420 from slipping off the support member 422. Removal of the tail portion 406 from the head portion 404 can be achieved by performing a reversal of these steps.

[0075] The mechanism 400 also comprises a housing member 410 that includes a first opening 414 and a second opening 412. The first opening 414 is adapted to receive an end of a support rod (not shown). In this particular embodiment of the invention, the first opening 414 is adapted to receive a circular support rod, although it should be understood that other shapes for the support rod could be used with suitable adaptations of the first opening 414. This embodiment of the invention envisages various sizes of housing member 410, and particularly the first opening 414, to accommodate support rods having 6 mm and 8 mm diameters. However, it should be understood that alternative sizes would also be suitable. The support rod is preferably constructed from a light-weight metal, plastic or wooden material, which is able to provide the screen with a high degree of horizontal rigidity when the tensioning mechanism is in use. The housing member 410, as with the projecting member 402, is preferably manufactured using injection moulding techniques.

[0076] The second opening 412 of the housing member 410 has a tapered internal profile that is adapted to forcibly receive and inwardly displace the resiliently deformable legs 408 of the tail portion 406. The insertion of the tail portion 406 within the second opening 412 of the housing member 410, as illustrated in FIGS. 7A and 7B of the drawings, requires the application of force by the user. As the tail portion 406, and particularly the legs 408, are slidably inserted into the second opening 412, the legs 408 will engage with the tapered internal profile of the housing member 410. This tapered internal profile consists of a pair of opposing internal surfaces 416 that converge toward one another and have a predetermined angular separation. As the user continues to apply force to the projecting member 402, the engagement of the resiliently deformable legs 408 with the pair of opposing internal surfaces 416 causes the legs 408 to flex and become inwardly displaced as the tail portion 406 is further inserted into the house member 410.

[0077] While the legs 408 are inwardly displaced, by the pair of opposing internal surfaces 416, the resilience of the legs 408 biases the projecting member 402 axially outward from the support rod. It is this bias which allows the head portion 404 to deliver a tensioning force to the fabric pocket of the screen.

[0078] The pair of opposing internal surfaces 416 has a predefined angular separation of approximately 17 degrees. However, it should be understood that alternative angular separations would also be possible and suitable. The greater the angular separation of the opposing internal surfaces 416, the greater the force required to insert and deflect the legs 408 within the housing member 410. Therefore, it follows that if more force is required to insert the tail portion 406, then a greater bias will subsequently be delivered to the head portion 404 of the projecting member 402.

[0079] Unlike the screen tensioning mechanism 100 described above, in the mechanism 400 described in this alternative embodiment of this invention, the housing member 410 allows for only one orientation of the projecting member 402 as there are only one pair of opposing internal surfaces 416. In order to achieve two or more different tensioning forces using a single pair of opposing internal surfaces 416, the strength of the resiliently deformable material used in the tail portion 406 can be changed. For example, the tail portion 406 can be manufactured from strip steel having a thickness of between 0.4 mm and 0.5 mm (or any similar thickness), in order to achieve two or more different tensioning forces. In any event, when the tail portion 406 is inserted into the housing member 410, as shown in FIGS. 7A, 7B and 8B, the legs 408 will engage with the pair of opposing internal surfaces 416.

[0080] To facilitate the positioning of the projecting member 402 in the required tension orientation (i.e. to prevent rotation of the projecting member 402 within the housing member 410), and to maintain engagement of the legs 408 with the opposing internal surfaces 416, the second opening 412 also includes a pair of opposing longitudinal slots 430. At least of one of the slots 430 (and preferably both of the slots 430) is adapted to slidably receive a protrusion 428 that is located on an outer surface of the projecting member 402. Preferably, a protrusion 428 is received in each of the longitudinal slots 430.

[0081] As the tail portion 406, and particularly the legs 408, are inserted into the second opening 412, at least one of the slots 430 slidably receives a protrusion 428 and substantially prevents rotation of the projecting member 402 during use. By preventing rotation of the projecting member 402 it is possible to maintain a constant bias, and thus tensioning force, by ensuring that the projecting member 402 remains in the required tension orientation.

[0082] It will be possible for a user to force the tail portion 406 into the housing member 410 until the point at which the distal ends of the legs 408 engage with an internal wall 440 of the housing member 410, or until the head portion 404 engages with, and abuts, the housing member 410. As the insertion force is withdrawn by the user, the bias applied to the projecting member 402 will cause the projecting member 402 to withdraw from the housing member 410 as shown by the arrow in FIG. 8B of the drawings. This movement or ejection of the projecting member 402 from the housing member 410 will continue until such time as the legs 408 are no longer being deflected by the opposing internal surfaces 416.

[0083] In order to prevent the projecting member 402 from becoming ejected from the housing member 410, the mechanism 400 comprises an abutting face 432 on the protrusion 428 that engages with at least one of the slots 430, as shown in FIGS. 7A and 7B of the drawings. The flexibility of the plastic material, from which the projecting member 402 is manufactured, allows the projecting member 402 and at least one protrusion 428 to be pushed through the second opening 412 as it is inserted into the housing member 410. The engagement of the abutting face 432 of the protrusion 428 and at least one of the slots 430 prevents the projecting member 402 from being released from the housing member 410, and assists the user with the installation process.

[0084] The word `comprising`, and forms of the word `comprising`, when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0085] As the present invention may be embodied in several forms without departing from the essential characteristics of the invention, it should be understood that the above described embodiments should not be considered to limit the present invention but rather should be construed broadly. Various modifications, improvements and equivalent arrangements will be readily apparent to those skilled in the art, and are intended to be included within the spirit and scope of the invention.

Claims

1. A screen tensioning mechanism for use in a retractable blind, said screen tensioning mechanism comprising: (a) a projecting member having a head portion and a resiliently deformable tail portion; and (b) a housing member comprising: (i) a first opening adapted to receive an end of a support rod; and (ii) a second opening having a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

2. The screen tensioning mechanism according to claim 1, wherein said head portion and said tail portion are integrally formed.

3. The screen tensioning mechanism according to claim 1, wherein said tail portion is releasably attached to said head portion.

4. The screen tensioning mechanism according to claim 3, wherein said tail portion comprises a length of resiliently deformable material.

5. The screen tensioning mechanism according to claim 1, wherein said tail portion comprises at least two legs extending from said head portion.

6. The screen tensioning mechanism according to claim 5, wherein said legs diverge from one another as they extend from said head portion.

7. The screen tensioning mechanism according to claim 5, wherein said tapered internal profile comprises a first pair of opposing internal surfaces which converge toward one another, and which in use engage and inwardly displace said legs.

8. The screen tensioning mechanism according to claim 7, wherein said first pair of opposing internal surfaces have a predefined angular separation that falls substantially in the range from 5 degrees to 25 degrees.

9. The screen tensioning mechanism according to claim 7, wherein said tapered internal profile further comprises a second pair of opposing internal surfaces having a predefined angular separation that is different from said first pair of opposing internal surfaces.

10. The screen tensioning mechanism according to claim 1, wherein said second opening further comprises a guide means which in use restricts rotational movement of said projecting member.

11. The screen tensioning mechanism according to claim 10, wherein said guide means comprises at least one longitudinal slot, said slot being adapted to slidably receive a protrusion on an outer surface of said projecting member.

12. The screen tensioning mechanism according to claim 11, wherein said protrusion is engageable with said slot to prevent said projecting member from being ejected from said housing member.

13. The screen tensioning mechanism according to claim 1, wherein said second opening comprises an internal lip that is engageable with said projecting member to prevent said tail portion from being ejected from said housing member.

14. A screen tensioning system for use in a retractable blind, said screen tensioning system comprising: (a) a support rod for insertion into a pocket of a retractable screen; and (b) a pair of tensioning mechanisms according to claim 1, said pair of tensioning mechanisms being positioned at opposing ends of said support rod, wherein in use, said head portion of each of said pair of tensioning mechanisms delivers an opposing tensioning force to said pocket of said retractable screen.

15. The screen tensioning system according to claim 14, wherein said head portion of each of said pair of tensioning mechanisms delivers an opposing tensioning force to an internal side wall of said pocket.

16. A screen tensioning system for use in a retractable blind, said screen tensioning system comprising: (a) a projecting member having a head portion and a resiliently deformable tail portion; and (b) a support rod comprising a housing member, said housing member having an opening with a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

17. The screen tensioning system according to claim 16, wherein said support rod and said housing member are integrally formed.

18. A screen tensioning mechanism for use in a retractable blind, said screen tensioning mechanism comprising: (a) a projecting member having a head portion and a resiliently deformable tail portion; and (b) a housing member comprising: (i) an end adapted to be inserted into an opening of a support rod; and (ii) an opening having a tapered internal profile adapted to forcibly receive said tail portion by inwardly displacing said tail portion, wherein in use, said resiliently deformable tail portion biases said projecting member axially outward from said support rod.

19. A support rod for a screen tensioning mechanism comprising a housing member, said housing member having an opening with a tapered internal profile, wherein said opening is adapted to forcibly receive a resiliently deformable tail portion of a projecting member to bias said projecting member axially outward from said support rod.

20. A projecting member for a screen tensioning mechanism comprising: (a) a head portion; and (b) a resiliently deformable tail portion, wherein said tail portion is adapted to be inserted into an opening in a housing member of a support rod to bias said projecting member axially outward from said support rod.