GB2577539A

GB2577539A - Roller blind assembly

Info

Publication number: GB2577539A
Application number: GB1815827.9A
Authority: GB
Inventors: Brookes Jason; Bridgewater Jonathan
Original assignee: WIDNEY Manufacturing Ltd
Current assignee: WIDNEY Manufacturing Ltd
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-01
Anticipated expiration: 2038-09-28
Also published as: GB2577539B; GB201815827D0

Abstract

A roller blind assembly 10 comprising a web of material 12 mounted to a winding mechanism 14 and extendable between parallel guide tracks 26. A draw bar 20 at the free end of the web has a connection 34 at either end coupled with the guide tracks. Each connection has a first clamp member (42 Fig.2) within an undercut channel (28) in the guide track and a second clamp member (44) engaging a guide track exterior surface. The clamp members are biased by first biasing mechanism (46, 54) to clamp the guide track and hold the draw bar in any extended position. Each connection may have a second biasing arrangement (50,56) which applies an additional biasing force drawing the first and second clamp members towards each other if the draw bar becomes skewed and spacing between the first clamp members increases, acting to maintain the draw bar orthogonal to the guide tracks. The blind assembly may comprise further guide bars (74, Fig.5) disposed rearward of the draw bar to support the web at curved regions of the guide tracks. The assembly may be used as a vehicle panoramic sunroof shade.

Description

Roller Blind Assembly

Technical Field of the Invention

The present invention relates to a roller blind assembly and in particular, but not exclusively, to a roller blind assembly for a vehicle.

Background to the Invention

Roller blinds are known in which a web of material is attached at one end to a winding mechanism for movement between extended and retracted positions. The winding mechanism typically includes a rotationally mounted roller, which may be a tube, on to which the majority of the web is wound when in a retracted position and from which the web can be unwound to one of a number of extended positions. The roller is usually spring loaded to wind the web onto the roller so that the blind is automatically retracted unless held in an extended position against the spring force. A draw bar is attached to the free end of the web and can be pulled by a user to extend the web. In order to hold the web in an extended position, it is known to engage the ends of the draw bar in retention formations such as hooks or notches which are fixed either side of the blind. An array of retention formations can be provided so that the web can be secured in a range of positions including fully and partially extended positions.

The known roller blind arrangements are satisfactory but it can be difficult to engage and disengage the draw bar from the notches or formations in order to hold or release the blind. A further problem is that the blind can only be secured in a number of discrete extended positions.

It is also known to use a roller blind as a screen for use in a vehicle. For example, it is known for vehicles to be provided with a sunroof and to use a roller blind to provide an adjustable shade for the sunroof In some known arrangements, the draw bar is slidably engaged at either end in a lateral guide track and slides along the track as the blind is extended and retracted. In GB 2 556 900 A, we proposed a cam arrangement which frictionally locks the draw bar to the tracks when the draw bar is rotated in order to releasably hold the blind in a range of extended position. The cam arrangement works effectively but in some applications it can be difficult to access the draw bar in order to rotate it when the blind is in an extended position. Accordingly, it would be desirable to provide an alternative locking arrangement which does not require the draw bar to be rotated to lock and unlock the blind.

A further issue that can arise in roller blinds where the draw bar slidably engages in tracks at either end is that the bar can become stuck in the tracks if it is not held square as the blind is extended and retracted.

An objective of the present invention is to provide an alternative roller blind assembly which overcomes, or at least mitigates, some or all of the limitations of the known roller blind assemblies.

It is a further objective to provide an alternative roller blind assembly that is easier for a user to lock in an extended position and/or to release.

Summary of the Invention

Aspects of the invention relate to a roller blind assembly and to a vehicle having a roller blind assembly.

According to first aspect of the present invention, there is provided a roller blind assembly comprising a web of material mounted at one end to a winding mechanism for movement between extended and retracted positions of the web, the winding mechanism applying a bias force tending to retract the web, a pair of lateral guide tracks spaced apart in substantially parallel relationship either side of the web and a draw bar attached to the web at a free end, the draw bar extending between the guide tracks and having a connection arrangement at either end coupled with a respective one of the guide tracks for movement along the guide track as the web is extended and retracted, wherein each guide track comprises an undercut channel, each connection arrangement having a first clamp member located within the undercut channel in engagement with an interior surface of the guide track and a second clamp member at an end of the draw bar in engagement with an exterior surface of the respective guide track, the first and second clamp members being movable relative to one another in a direction parallel to a longitudinal axis of the draw bar and each connection arrangement including a first biasing mechanism for biasing the first and second clamp members towards each other so as to clamp a portion of the guide track between them, the arrangement configured such that, in use, the connection arrangements clamp the guide tracks with sufficient friction force to hold the draw bar at any given position along the guide tracks against the bias force of the winding mechanism but which friction force can be overcome by a user to extend or retract the web by sliding the draw bar along the guide tracks.

In a roller blind assembly in accordance with the first aspect of the invention, the connection arrangements which clamp to the guide tracks enables the web to be extend and retracted by a user simply pulling or pushing on the draw bar to slide it along the tracks, with the clamping arrangement automatically holding the draw bar in the selected position when it is released. This is very easy to use and allows for infinite adjustment of the blind along the guide tracks.

In an embodiment, the draw bar includes a hollow main body member, each second clamp member having a projection non-rotatably received in an end of the hollow main body member, and wherein in each connection arrangement the first clamp member is mounted to a spigot which slidably extends through an aperture in the second clamp member to project beyond the second clamp member within the hollow main body member, the first biasing mechanism comprising a first compression spring operatively connected between the spigot and the second clamp member to apply a bias force to the spigot tending to draw the first damp member towards the second clamp member.

In an embodiment, each guide track comprises a C section channel member defining an elongate slot extending longitudinally along an inner wall of the channel member which slot opens into the undercut channel, the spigot of each connecting arrangement projecting through the slot of its respective channel member. The slot may divide the inner wall into a first wall portion and second wall portion either side of the slot, and the first and second clamp members may engage inner and outer faces respectively of the first and second wall portions of their respective guide track.

In an embodiment, the first bias mechanisms are operative draw the first clamp members into contact with inner surfaces of the guide tracks such that when the draw bar is aligned substantially orthogonal to the guide tracks, the first clamp members are spaced apart by a first predetermined distance, each connecting arrangement comprising a second biasing arrangement operative in use to apply an additional biasing force tending the draw the first and second damp members towards each other in the event the spacing between the first clamp members is increased beyond the first predetermined distance, at least where the increase in spacing is by a predetermined amount or more.

In an embodiment, the second biasing mechanism comprises an abutment fixedly located within the hollow main body and a second compression spring, the spigot projecting inwardly beyond the abutment, the second compression spring being operative between the abutment and an abutment fixed relative to the spigot so as to apply said additional bias force to the spigot tending to draw the first and second clamp members towards each other at least when the first clamp members are spaced apart by a distance which is greater than the first predetermined distance by the predetermined amount or more. The arrangement may be configured such that when the draw bar is aligned substantially orthogonal to the guide tracks and the first clamp members are spaced apart by said first predetermined distance, there is free play between the abutment, the second compression spring and the spigot abutment such that the second biasing arrangement does not apply an additional biasing force tending the draw the first and second clamp members towards each other. The second biasing arrangement may be configured such that if the spacing between the first clamp members is increased, the free play is gradually taken up until the second compression spring begins to apply said additional bias force once the spacing as increased by said predetermined amount. The abutment may be an abutment block fixedly located in the main body.

In an embodiment, at least part of the guide tracks are curved and the roller blind assembly includes a guide bar extending between the guide tracks below the web, the guide bar being spaced rearwardly from the draw bar when the web is fully extended to support the web and having a connection arrangement at either end coupled with a respective one of the guide tracks for movement along the guide track as the web is extended and retracted, the connection arrangements of the guide bar having substantially all the features of the connection arrangements of the draw bar set out above. Accordingly, each connection arrangement of the guide bar may have a first clamp member located within the undercut channel in engagement with an interior surface of the guide track and a second clamp member at an end of the guide bar in engagement with an exterior surface of the respective guide track, the first and second clamp members being movable relative to one another in a direction parallel to a longitudinal axis of the guide bar and each connection arrangement including a first biasing mechanism for biasing the first and second clamp members towards each other so as to clamp a portion of the guide track between them. In an embodiment, the guide bar includes a hollow main body member, each second clamp member having a projection non-rotatably received in an end of the hollow main body member, and wherein in each connection arrangement the first clamp member is mounted to a spigot which slidably extends through an aperture in the second clamp member to project beyond the second clamp member within the hollow main body member, the first biasing mechanism comprising a first compression spring operatively connected between an abutment fixed relative to the spigot and the second clamp member to apply a bias force to the spigot tending to draw the first clamp member towards the second clamp member. In an embodiment, each guide track comprises a C section channel member defining an elongate slot extending longitudinally along an inner wall of the channel member which slot opens into the undercut channel, the spigot of each connecting arrangement projecting through the slot of its respective channel member. The slot may divide the inner wall into a first wall portion and second wall portion either side of the slot, and the first and second clamp members may engage inner and outer faces respectively of the first and second wall portions of their respective guide track.

In an embodiment, the first bias mechanisms are operative draw the first clamp members into contact with inner surfaces of the guide tracks such that when the guide bar is aligned substantially orthogonal to the guide tracks, the first clamp members are spaced apart by a first predetermined distance, each connecting arrangement comprising a second biasing arrangement operative in use to apply an additional biasing force tending the draw the first and second clamp members towards each other in the event the spacing between the first clamp members is increased beyond the first predetermined distance, at least where the increase in spacing is by a predetermined amount or more.

In an embodiment, the second biasing mechanism comprises an abutment fixedly located within the hollow main body and a second compression spring, the spigot projecting inwardly beyond the abutment, the second compression spring being operative between the abutment and an abutment fixed relative to the spigot so as to apply said additional bias force to the spigot tending to draw the first and second clamp members towards each other at least when the first clamp members are spaced apart by a distance which is greater than the first predetermined distance by the predetermined amount or more. The arrangement may be configured such that when the guide bar is aligned substantially orthogonal to the guide tracks and the first clamp members are spaced apart by said first predetermined distance, there is free play between the abutment, the second compression spring and the spigot abutment such that the second biasing arrangement does not apply an additional biasing force tending the draw the first and second clamp members towards each other. The second biasing arrangements may be configured such that if the spacing between the first clamp members is increased, the free play is gradually taken up until the second compression spring begins to apply said additional bias force once the spacing as increased by said predetermined amount. The abutment fixed relative to the main body may be an abutment block fixedly located in the main body.

In an embodiment, the first biasing arrangements of the guide bar are configured to apply a lower clamping force to the guide tracks than is applied by the first biasing arrangements of the draw bar.

In an embodiment, each connection arrangement of the guide bar includes a pull tab projecting forwardly from the first clamp member within the undercut channel beyond the first clamp member of the draw bar, the pull tab having a fixed length and an abutment formation which locates in front of the respective first clamp member of the draw bar, the arrangement being, configured such that in use, the abutment formations are engaged by the respective first clamp members of the draw bar when the draw bar is moved from a retracted position in an extension direction by a set distance, continued movement of the draw bar in the extension direction beyond the set distance causing the guide bar to be drawn forward in the extension direction by draw bar acting on the pull tab members. Each of the first clamp members of the draw bar may define a slot within which a respective pull tab of the guide bar is slidably received. The first clamp members may be "H" shaped, The arrangement may be configured such that when the draw bar is moved from a fully extended position towards a fully retracted position, the first clamp members slide relative to the pull tabs of the guide bar such that the guide bar remains stationary until the draw bar contacts the guide bar, further movement of the draw bar towards a fully retracted position causing the guide bar to be pushed towards a fully retracted position by the draw bar.

Each pull tab may comprise an elongate polymeric strip. Each pull tab may comprise a polymeric (e.g. nylon) cable tie.

In an embodiment, the guide bar is a first guide bar and the roller blind assembly comprises a second guide bar, the second guide bar extending between the guide tracks below the web and being spaced rearwardly from the first guide bar when the web is fully extended, wherein the second guide bar has similar connection arrangements to the first guide bar, the pull tabs of the second guide bar extending forwardly beyond the respective first clamp members of the first guide bar and those of the draw bar, abutment formations of the second guide bar pull tabs being engaged by the respective first clamp members of the draw bar when the draw bar has been moved from a fully retracted position in the extension direction by a second set distance, the arrangement being such that, in use, continued movement of the draw bar in the extension direction beyond the second set distance causes the second guide bar to be drawn forward in the extension direction by the draw bar acting on the abutment formations of pull tabs of the second guide bar.

According to second aspect of the present invention, there is provided a roller blind assembly comprising a web of material mounted at one end to a winding mechanism for movement between extended and retracted positions of the web, the winding mechanism applying a bias force tending to retract the web, a pair of lateral guide tracks spaced apart in substantially parallel relationship either side of the web and a draw bar attached to the web at a free end, the draw bar extending between the guide tracks and having a first slide member at either end slidably engaged in a respective guide track, wherein the guide tracks have a curved region and the roller blind assembly includes a guide bar extending between the guide tracks below the web, the guide bar being spaced rearwardly from the draw bar when the web is fully extended to support the web and having a second slide member at either end slidably engaged in a respective one of the tracks, the guide bar being operatively connected with the draw bar by means of pull tabs projecting forwardly from the second slide members beyond their respective first slide members, the pull tabs having a fixed length and an abutment formation which locates in front of the respective first slide members of the draw bar, the arrangement being configured such that in use, the abutment formations are engaged by the respective first slide members of the draw bar when the draw bar is moved from a retracted position in an extension direction by a set distance, continued movement of the draw bar in the extension direction beyond the set distance causing the guide bar to be drawn forward in the extension direction by draw bar acting on the pull tab members.

Each of the first slide members of the draw bar may define a slot within which a respective pull tab of the guide bar is slidably received. The first slide members may be 1-1" shaped, The arrangement may be configured such that when the draw bar is moved from a fully extended position towards a fully retracted position, the first slide members slide relative to the pull tabs of the guide bar such that the guide bar remains stationary until the draw bar contacts the guide bar, further movement of the draw bar towards a fully retracted position causing the guide bar to be pushed towards a fully retracted position by the draw bar.

The roller blind assembly according to either of the first or second aspects of the invention may be configured for use in a vehicle, especially a construction vehicle. The roller blind assembly may be configured for use as shade for a sunroof of the 25 vehicle In accordance with a third aspect of the invention, there is provided a vehicle comprising a roller blind in accordance with the first aspect or the second aspect of invention as set out above. The vehicle may be a construction vehicle. The vehicle may have a sunroof and the blind assembly may be configured as a screen for the sunroof

Detailed Description of the Invention

In order that the invention may be more clearly understood an embodiment will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 Figure 2 is a perspective view of a roller blind assembly in accordance with an embodiment of an aspect of the invention; is a cross sectional view through one end of a draw bar and an adjacent guide track of the roller blind assembly of Figure 1 showing a connection arrangement slidably connecting the draw bar to the guide track, taken on line X-X of Figure 1; is a perspective view of the end region of the draw bar of Figure 2, in which a main body of the draw bar is shown ghosted so that internal detail can be seen; is a perspective view of a clamping unit forming part of the connection arrangement of Figures 2 to 3; is a view similar that of Figure 1 but also showing in an exploded manner a draw bar and first and second guide bars forming part of the roller blind assembly; is a perspective view of an end region of a second guide bar forming part of the roller blind assembly of Figures 1 and 5; is a perspective view of an end region of a first guide bar forming part of the roller blind assembly of Figures 1 and 5; and is a perspective view of an end region of a draw bar forming part of the roller blind assembly of Figures 1 and 5.

Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 1 illustrates an embodiment of a roller blind assembly 10 in accordance with an aspect of the invention. The roller blind assembly 10 in this embodiment is configured for use as a shade for a sunroof in a motor vehicle. In particular, the roller blind assembly 10 is configured for use as a shade for a panoramic sunroof in a l0 construction vehicle such as a mechanical digger. However, roller blind assemblies in accordance with an aspect of the invention are not limited to use as a shade for a sunroof in a vehicle but can be adapted for a wide variety of uses on a vehicle and could also be used in non-vehicle applications, such as a blind for a window in a building or the like.

The roller blind assembly 10 is adapted to be mounted inside a vehicle cab (not shown) below the sunroof where a driver can access the blind in order to extend and/or retract a web 12 forming part of the blind to vary the degree of shade provided. The roller blind assembly 10 includes a roller blind cassette 14 which in use is mounted to the vehicle body so as to extend transversely to the rear of the sunroof The roller blind cassette 14 includes a housing 16 fixedly mounted to the vehicle body in which a roller 18 is supported for rotation about its longitudinal axis Z. The web 12 of material is attached at a first end to the roller and can be wound onto and off the roller in a conventional manner. The roller 18 is spring loaded so as to rotate in a direction which winds the web 12 onto the roller such that the web is automatically retracted unless held in an extended position against the spring force. The roller 18 and spring arrangement (not shown) can be considered as a winding mechanism for the blind.

A generally rigid draw bar 20 is fixed to the free, forward end of the web 12. A handle 22 is optionally attached at a central location to the draw bar and/or to the forward end of the web 12. The handle 22 extends downwardly so that a user of the vehicle can grab the handle 22 in order to draw the web 12 forwardly to an extended position against the spring force of the winding mechanism and/or to guide the web rearwardly as it is retracted by the winding mechanism. The draw bar 20 can be fixed to the free end of the web 12 in any suitable manner. In the present embodiment, the free end of the web 12 is formed into a loop 24 and the draw bar is inserted into the loop. However, other means for fixing the draw bar to the web can be adopted. For example, the web could be adhered or clamped to the draw bar 20.

A pair of lateral guide tracks 26 are mounted to the vehicle body either side of the sunroof extending in a longitudinal direction of the vehicle, orthogonal to the longitudinal axis of the roller. Each guide track defines an undercut channel 28 which opens inwardly (that is to say on the side directed towards the web) by means of a longitudinal slot 30 in an inner wall 32 of the guide track. The slot 30 divides the inner I1 wall 32 into a first, upper wall portion 32a and second, lower wall portion 32b. The guide tracks 26 can be made of any suitable material in any suitable way. For example, the guide tracks could be made from metallic, polymeric, or composite material. In a non-limiting embodiment, the guide tracks are formed from extruded C-section lengths.

The roller blind assembly 10 in the embodiment as shown is adapted for use in a vehicle having a panoramic sunroof which has an upper generally planar section but which curves downwardly at a forward end of the vehicle cab. To accommodate this, the guide tracks 26 each have a straight section 26a which extends alongside the planar section of the sunroof from the rear towards the front and a forward section 26b which curves downwardly.

The draw bar has a longitudinal axis Y which corresponds with the direction of line X-X in Figure 1 and in normal use extends transversely of the vehicle, orthogonal to the guide tracks. The draw bar 20 has a connection arrangement (indicated generally at 34) at either end which slidably couples the draw bar 20 to the adjacent guide track 26 so that the draw bar can be moved forwardly along the tracks to extend the web 12 in an extension direction A and rearwardly in the opposite direction to retract the web. The connection arrangements 34 are also operative to hold the draw bar 20 at any given location along the guide tracks against the bias force of the winding mechanism so that the web 12 can be held in a fully or partially extended position. The connection arrangement 34 at the left hand side of the draw bar 20 as shown in Figure 1 will now be described with reference to Figures 2 to 4. However, it should be understood that a corresponding connection arrangement 34 is provided on the right hand side, the connection arrangement on the right hand side being a mirror image of the one on the left.

With reference to Figures 2 to 4, the draw bar 20 has a hollow main body 36 which extends over the majority of the distance between the two guide tracks 26. The main body 36 can be made of any suitable material such as extruded plastic or aluminium or the like. The main body 36 is generally rigid, or at least sufficiently rigid that it supports the free end of the web and can be used the pull the web from the roller 18 to extend the blind. In the present embodiment, the main body 36 is a hollow tubular member having cross section which is broadly in the form of an elongate oval or which can be considered as rectangular with curved short sides. However, this is not essential and the main body could have a different shape in cross section, though it is preferable if the shape is non-circular.

The connection arrangement 34 includes a clamping unit 38 as shown on its own in Figure 4. The clamping unit has an elongate rod-like spigot 40 to which is mounted in turn from an outside end of the spigot to and inside end a first clamp member 42 (also referred to as a first slide member), a second clamp member 44, a first compression spring 46, an abutment block 48 and a second compression spring 50. The spigot 40 projects through corresponding bores in the first and second clamp members 42, 44 and the abutment block 48. The first clamp member 43 is located at the outer end of the spigot 40 and is held on the spigot by a first circlip 52 which engages in a first groove in the spigot. The second clamp member 44 is located on the spigot adjacent the first clamp member. The first compression spring 46 is a helical coil spring mounted about the spigot on the opposite side of the second clamp member 44 from the first clamp member 42. The first compression spring is mounted about the spigot between the second clamp member and a second circlip 54 engaged in a second groove in the spigot inwardly of the second clamp member. The abutment block 48 is located on the inwardly of the second circlip 54 and the second compression spring 50 is a further helical coil spring mounted about the spigot between the abutment block 48 and a third circlip 56 engaged in a third groove 57 in the spigot 40.

The second clamp member 44 has a mounting portion 58 which locates within the interior of the main body 36 and a clamping head 60 which locates outside the main body 36. When the clamping unit 38 is mounted to the main body 36, the mounting portion 58 of the second clamp member 44, the abutment block 48, the first and second compression springs 46, 50 and the majority of the spigot 40 are received inside the main body. The mounting portion 58 on the first clamp member has an elongate oval cross sectional shape which corresponds to shape of the interior of the main body 36 and is a close sliding fit in the main body so that the second clamp member 44 is held rotationally fast with the main body.

The clamping head 60 of the second clamp member 44 engages an outer surface 62 of the upper and lower wall portions 32a, 32b of the inner wall of the guide track 26, as best seen in Figure 2. The clamping head 60 also has a lip 64 which locates below a lower wall of the guide track 26 so as to prevent the second clamp member 44, and hence the main body, from rotating relative to the guide track beyond a limited amount.

The first clamp member 42 locates inside the undercut channel 28 and is arranged to abut an inner surface 66 of the upper and lower wall portions 32a, 32b of the inner wall of the guide track, as also best seen in Figure 2. The first clamp member 42 is configured to be a close sliding fit inside the undercut channel 28 and is generally "H" shaped, having a pair of outer flanges 68, 70 interconnected by a central web 72. The flanges 68, 70 are arranged to be a close sliding fit between the upper and lower walls of the guide track. The first clamp member 42 has a width which is slightly less than the corresponding width of the undercut channel 28 so that the first damp member 42 can tilt to a limited extent within the undercut channel relative to the longitudinal axis of the channel. Outer edges of the outermost flange 70 are tapered at the front and rear to assist in inserting the second clamp member in the undercut channel 28.

The clamping unit 38 is configured so that when the draw bar 20 is assembled to a guide track 26 with the first clamp member 42 inside the undercut channel 28 and the second clamp member 44 engaged with the guide track on the outside, the first compression spring 46 is compressed between the second clamp member 44 and the first circlip 54 and is operative to apply a bias force tending to draw the first and second clamp members towards each other such that they clamp the upper and lower wall portions 32a, 32b of the inner wall of the guide track between them. This can be considered as a first biasing mechanism and the arrangement is configured such that the combined friction force produced by the clamping units engaging with the guide tracks on either side of the draw bar is sufficient to hold the draw bar at any given position along the guide tracks against the bias force of the web winding mechanism in the cassette 14. However, the friction force can be overcome by a user to extend or retract the web 12 by simply pushing or pulling on the draw bar, say by using the handle 26, to slide the draw bar along the guide tracks 26. This provides a particularly effective locking mechanism for the blind, whereby the user can extend the blind from a retracted position simply by pulling on the draw bar 20 or its handle 22 to move it forwardly along guide tracks to a desired position, unwinding the web 12 from the roller 18. When the user lets go of the draw bar 20, the friction forces generated by the clamping units 38 hold the draw bar 20 and the web 12 in the selected position against the bias force of the winding mechanism. To further adjust the blind, the user can either move the draw bar 20 further forward along the guide tracks 26, if the blind is not fully extended, or slide the draw bar back along the guide tracks towards the roller blind cassette 14. In this latter case, the winding mechanism will operate to take up any slack in the web by winding it back on to the roller 18. This friction locking arrangement does not require the draw bar 20 to be twisted to lock it in position or engagement of the draw bar with locking formations and so is easy to use and highly adjustable.

In normal use, the draw bar 20 is aligned with its longitudinal axis Y orthogonal to the inner walls of the guide tracks 26. Since the first clamp members 42 are biased into engagement with the inner surfaces 66 of the inner walls 32 of the guide tracks, they are normally maintained at a set spacing determined by the spacing between the guide tracks. This can be regarded as a first predetermined spacing between the first clamp members 42. However, in certain circumstances it is possible for a user to advance one end of the draw bar 20 further along its respective guide track 26 than the other end so that the draw bar becomes skewed. When this happens, the spacing between the first clamp members 42 is increased from the first predetermined distance because the draw bar extends between the guide tracks at an angle other than 90 degrees.

In this circumstance, it is possible for the draw bar to become stuck and difficult to move. To resist this, the roller blind assembly 10 has an anti-skew mechanism comprising a second biasing arrangement in each of the clamping units 38 which applies an additional biasing force tending to draw the first and second clamp members towards each other in the event that the spacing between the first clamp members 42 is increased beyond the first predetermined distance by a predetermined amount. This additional bias force acts together with the bias force of the first biasing mechanism 46 to draw the first clamp members 42 inwardly towards the second clamp members 44 and has the effect of tending to move the draw bar 20 back into orthogonal alignment with the guide tracks.

The second biasing mechanism in each clamping unit 38 comprises the abutment block 48 and the second compression spring 50. The abutment block 48 has an outer profile which conforms to the inner cross-sectional shape of the main body 36 and is a close sliding fit in the main body. When the clamping unit is mounted to the man body 36 of the draw bar, the abutment block is fixed in position relative to the main body. In the present embodiment, the abutment block is fixed in position by indenting the main body to produce dimples 73 which engage in corresponding recess in the abutment block. However, other arrangements for fixing the abutment block can be adopted such as by means of fasteners inserted through the main body into the abutment block.

The clamping units 38 are arranged so that when the draw bar 20 is assembled to the guide tracks 26 with its longitudinal axis Y orthogonal to the guide tracks 26, there is a small amount of free play W between the second compression spring 50, the abutment block 48 and the third circlip 56 on the spigot 40. This ensures that the second biasing mechanism is not operative in normal use and so does not affect the usual friction force generated by the first biasing mechanism, which might otherwise adversely affect the user's feel when adjusting the blind. However, should the draw bar become skewed and the spacing between the first clamp members 42 increased, the free play is gradually taken up until the second compression spring 50 is compressed between the abutment block 48 and the third circlip 56 and starts to apply an additional bias force to the spigot tending to draw the first clamp member 42 inwardly. This additional bias force tends to restore the draw bar to its usual orientation with its longitudinal axis Y orthogonal to the guide tracks. It will be appreciated that the greater the angle of skew, the more the second compression spring 50 is compressed and the greater the restoring force applied by the second biasing mechanism. Whilst a certain amount of free play in the second biasing mechanism can be advantageous, it is possible that the second biasing mechanism is configured with no free play so that it contributes to the usual bias force clamping the first and second clamp members to guide tracks even when the draw bar 20 is orthogonal to the guide tracks 26.

In the clamping units 38, circlips 52, 54, 56 located in grooves in the spigot 40 are used to provide fixed abutments on the spigot. However, it will be appreciated that other arrangements for providing fixed abutments on the spigot could be used.

In the present embodiment in which the guide tracks 26 curve downwardly at the front, to prevent the web 12 from encroaching in to the head space in the vehicle cab when the draw bar 20 moves into the curved forward section 26a of the guide tracks, the roller blind assembly has first and second guide bars 74, 76 which locate beneath the web 12 and are spaced apart rearwardly of the draw bar 20 when the web 12 is extended as shown in Figure 1. The guide bars 74, 76 are each slidably mounted to the guide tracks 26 by means of a connection arrangement at either end which are substantially the same as those of the draw bar 20 previously described above with reference to Figures 2 to 4. Thus each guide bar 74, 76 comprises a hollow main body 36 and a clamping unit 38 mounted to each end for engagement with a respective guide track 26. However, the first biasing mechanisms of clamping units in the guide bars 74, 76 are arranged to apply a lower clamping force than those of the draw bar so that the guide bars 74, 76 are easier to slide along the guide tracks 26 but without being too loose. To this end, the first compression springs 46 in the connection arrangements of the guide bars 74, 76 may have a lower spring rate that those used in the draw bar.

The first and second guide bars 74, 76 are not attached to the web but are moved along the guide tracks by the draw bar 20 as the web is extended and retracted. To this end, the guide bars 74, 76 are provided an elongate pull tabs 78a, 78b, each of which is attached to a respective one of the first clamp members 42 (also known as a second slide member) and extends forwardly for co-operation with the first clamp member 42 of the draw bar 20 on its respective side. Accordingly, the first guide bar 74 has first pull tabs 78a whilst the second guide bar 76 has second pull tabs 78b. The pull tabs have a fixed length with the first pull tabs 78a being shorter than the second pull tabs 78b. The pull tabs 78a, 78b in the present embodiment comprise elongate plastic strips which whilst flexible, will not stretch under tension during normal operation of the roller blind. In a convenient manner, the pull tabs 78a, 78b could be manufactured from conventional plastic (e.g. nylon) cable ties of the appropriate length.

Figure 6 shows an end region of the second, uppermost guide bar 76 showing a second pull tab 78b attached at one end to a forward part of the first clamp member 42 and projecting forwardly. Figure 7 shows the corresponding end region of the first, intermediate guide bar 74. A first pull tab 78a is attached at one end to a forward part of the first clamp member 42 of the first guide bare and projects forwardly whilst the second pull tab 78b of the second guide bar 76 extends over the top of the first pull tab 78a and is slidably received in a slot defined between the flanges 68, 70 of the first clamp member 42. Figure 8 shows the corresponding an end region of the draw bar 20.

Both the first and second pull tabs 78a, 78b of the first and second guide bars 74, 76 are slidably received in a slot defined between the flanges 68, 70 of the first clamp member 42. Each of the first and second pull tabs 78a, 78b has an abutment formation 80a, 80b at is free, forward end. These abutments are wider than the spacing between the flanges 68, 70 and so are engaged by the flanges when the draw bar is moved forwardly to extend the web. Figure 8 shows the abutment 80a of the first tab 78a of the first guide bar engaged by the first clamp member 42 of the draw bar, whilst the abutment 80b of the second pull tab 78b is not yet engaged. It will be appreciated that corresponding pull tab arrangements are provided at the other ends of the guide and draw bars.

In operation, when the web is fully reattached, the draw bar 20 is located in a fully retraced position close to the a roller blind cassette 14, with the first guide bar 74 adjacent a rear edge of the draw bar and the second guide bar 76 adjacent a rear edge of the first guide bar 74. In order to extend the web 12, the draw bar 20 is moved forwardly in the extension direction A along the guide tracks 26. Over an initial range of movement, the first and second pull tabs 78a, 78b are free to slide over the first clamp member 42 of the draw bar and so remain stationary as the draw bar is advanced. Once the draw bar has moved through a first predetermined distance in the extension direction dictated by the length of the first pull tabs 78a, the first clamp members 42 of the draw bar 20 engage with the abutments 80a at the ends of the first pull tabs 78a. Further movement of the draw bar in the extension direction A beyond the first predetermined distance results in the first guide bar 74 being drawn along the guide tracks by the first pull tabs 78a. At this stage, the second pull tabs 78b attached to the second guide bar 76 are still free to slide over the first clamp members 42 of the draw bar 20 so that the second guide bar 76 remains stationary. Once the draw bar 20 has moved through a second predetermined distance in the extension direction A dictated by the length of the second pull tabs 78b, the first clamp members 42 of the draw bar 20 engage with the abutments 80b at the ends of the second pull tabs 78b. Further movement of the draw bar beyond the second predetermined distance in the extension direction A results in both the first and second guide bars 74, 76 being drawn along the guide tracks by the first and second pull tabs 78a, 78b respectively. Once the draw bar 20 is moved to a fully extended position, the first and second guide bars 74, 76 are spaced behind the draw bar 20 by distances that are determined by the respective lengths of the first and second pull tabs 78a, 78b. To retract the web 12, the draw bar is moved rearwardly along the guide tracks, back towards the roller blind cassette 14. As the draw bar 20 is moved rearwardly from the fully extended position, the first and second pull tabs 78a, 78b are free to slide over their respective first clamp members 42 of the draw bar so that the first and second guide bars 74, 76 remain stationary until the draw bar is moved rearwardly sufficient that it contacts the first guide bar 74. Continued movement of the draw bar 20 towards the cassette 14 causes the first guide bar 74 to be push backwards by the draw bar 20. Initially, the second guide bar 76 will remain stationary until it is collected by the first guide bar 74. Thereafter, the first and second guide bars 74, 76 are both moved rearwardly with the draw bar 20 until the fully retracted position is reacted.

The pull tabs 78a, 78b are conveniently located within their respective guide tracks 26 so that they are not visible and will not catch on any cabling or other features inside the vehicle cab. The pull tabs 78a, 78b are also held in the slots defined between the flanges 68, 70 of the first clamp members of the draw bar 20 (and that of the first guide bar 74 in the case of the second pull tabs 78b) buy the guide tracks.

It will be appreciated that the spacing between the draw bar 20, the first guide bar 74 and the second guide bar 76 can be adjusted by selecting pull tabs 78a, 78b of an appropriate lengths. Whilst the present embodiment uses two guide bars 74, 76, the roller blind assembly 10 could be modified to have only a single guide bar or more than two guide bars. Furthermore, where there are two or more guide bars, the pull tab system could be modified so that the pull tabs on the second and any subsequent guide bars engage with the first clamp members of the guide bar in front rather than the draw bar when the blind is extend.

It should be appreciated that the roller blind assembly 10 in accordance with an aspect of the invention is not limited to use in a vehicle having a panoramic sunroof and need not have guide tracks 26 with curved forward sections 26b. Where the guide tracks 26 are entirely straight, the first and second guide bars 74, 76 and pull tabs as described above can be omitted.

The above embodiment is described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims. For example, the blind assembly need not be used as a horizontal blind for the vehicle sunroof but could be used as a vertical blind for a vehicle window or as a blind in any desired orientation for a window in a building.

Claims

CLAIMS1. A roller blind assembly comprising a web of material mounted at one end to a winding mechanism for movement between extended and retracted positions of the web, the winding mechanism applying a bias force tending to retract the web, a pair of lateral guide tracks spaced apart in substantially parallel relationship either side of the web and a draw bar attached to the web at a free end, the draw bar extending between the guide tracks and having a connection arrangement at either end coupled with a respective one of the guide tracks for movement along the guide track as the web is extended and retracted, wherein each guide track comprises an undercut channel, each connection arrangement having a first clamp member located within the undercut channel in engagement with an interior surface of the guide track and a second clamp member at an end of the draw bar in engagement with an exterior surface of the respective guide track, the first and second clamp members being movable relative to one another in a direction parallel to a longitudinal axis of the draw bar and each connection arrangement including a first biasing mechanism for biasing the first and second clamp members towards each other so as to clamp a portion of the guide track between them, the arrangement configured such that, in use, the connection arrangements clamp the guide tracks with sufficient friction force to hold the draw bar at any given position along the guide tracks against the bias force of the winding mechanism but which friction force can be overcome by a user to extend or retract the web by sliding the draw bar along the guide tracks.
2. A roller blind assembly as claimed in claim 1, wherein the draw bar includes a hollow main body member, each second clamp member having a projection non-rotatably received in an end of the hollow main body member, and wherein in each connection arrangement the first clamp member is mounted to a spigot which slidably extends through an aperture in the second clamp member to project beyond the second clamp member within the hollow main body member, the first biasing mechanism comprising a first compression spring operatively connected between an abutment fixed relative to the spigot and the second clamp member to apply a bias force to the spigot tending to draw the first clamp member towards the second clamp member.
A roller blind assembly as claimed in claim 2, wherein each guide track comprises a C section channel member defining an elongate slot extending longitudinally along an inner wall of the channel member which slot opens into the undercut channel, the spigot of each connecting arrangement projecting through the slot of its respective channel member.
4. A roller blind assembly as claimed in claim 3, wherein the slot divides the inner wall into a first wall portion and second wall portion either side of the slot, the first and second clamp members engaging inner and outer faces respectively of the first and second wall portions of their respective guide track.
5. A roller blind assembly as claimed in any one of claims 1 to 4, wherein the first bias mechanisms are operative draw the first clamp members into contact with inner surfaces of the guide tracks such that the first clamp members are spaced apart by a first predetermined distance when the draw bar is aligned substantially orthogonal to the guide tracks, each connecting arrangement comprising a second biasing arrangement operative in use to apply an additional biasing force tending the draw the first and second clamp members towards each other in the event the spacing between the first clamp members is increased beyond the first predetermined distance, at least where the increase in spacing is by a predetermined amount or more.
6. A roller blind assembly as claimed in claim 5 when dependent on claim 2, wherein the second biasing mechanism comprises an abutment fixedly located within the hollow main body and a second compression spring, the spigot projecting inwardly beyond the abutment, the second compression spring being operative between the abutment and an abutment fixed relative to the spigot so as to apply said additional bias force to the spigot tending to draw the first and second clamp members towards each other, at least when the first clamp members are spaced apart by a distance which is greater than the first predetermined distance by the predetermined amount or more.
A roller blind assembly as claimed in claim 6, the arrangement being configured such that when the draw bar is aligned substantially orthogonal to the guide tracks and the first clamp members are spaced apart by said first predetermined distance, there is free play between the abutment, the second compression spring and the spigot abutment such that the second biasing arrangement does not apply an additional biasing force tending the draw the first and second clamp members towards each other.
8. A roller blind assembly as claimed in claim 7, wherein the second biasing arrangements are configured such that if the spacing between the first clamp members is increased from the first predetermined spacing, the free play is gradually taken up until the second compression spring begins to apply said additional bias force once the spacing as increased by said predetermined amount.
9. A roller blind assembly as claimed in any one of claims 1 to 8, wherein at least a part of the guide tracks are curved, the roller blind assembly including a guide bar extending between the guide tracks below the web, the guide bar being spaced rearwardly from the draw bar when the web is fully extended to support the web and having a connection arrangement at either end coupled with a respective one of the guide tracks for movement along the guide track as the web is extended and retracted, the connection arrangements of the guide bar having substantially all the features of the connection arrangements of the draw bar as claimed in any one of claims 1 to 8.
10. A roller blind as claimed in claim 9, wherein the first biasing arrangements of the guide bar are configured to apply a lower clamping force to the guide tracks than is applied by the first biasing arrangements of the draw bar.
11. A roller blind assembly as claimed in claim 9 or claim 10, wherein each connection arrangement of the guide bar includes a pull tab projecting forwardly from the first clamp member within the undercut channel beyond the first clamp member of the draw bar, the pull tab having a fixed length and an abutment formation which locates in front of the respective first clamp member of the draw bar, the arrangement being configured such that in use, the abutment formations are engaged by the respective first clamp members of the draw bar when the draw bar is moved from a retracted position in an extension direction by a set distance, continued movement of the draw bar in the extension direction beyond the set distance causing the guide bar to be drawn forward in the extension direction by the pull tab members.
12 A roller blind assembly as claimed in claim 11, wherein each of the first clamp members of the draw bar define a slot within which a respective pull tab of the guide bar is slidably received.
13. A roller blind assembly as claimed in claim 12, wherein the arrangement is configured such that when the draw bar is moved from a fully extended position towards a fully retracted position, the first clamp members slide relative to the pull tabs of the guide bar such that the guide bar remains stationary until the draw bar contacts the guide bar, further movement of the draw bar towards a fully retracted position causing the guide bar to be pushed towards a fully retracted position by the draw bar.
14. A roller blind assembly as claimed in any one of claims 11 to 13, wherein each pull tab comprises an elongate polymeric strip.
15. A roller blind assembly as claimed in any one of claims 9 to 14, wherein the guide bar is a first guide bar and the roller blind assembly comprises a second guide bar, the second guide bar extending between the guide tracks below the web and being spaced rearwardly from the first guide bar when the web is fully extended, wherein the second guide bar has similar connection arrangements to the first guide bar, the pull tabs of the second guide bar extending forwardly beyond the respective first clamp members of the first guide bar and of the draw bar, the abutment formations of the second guide bar pull tabs being engaged by the respective first clamp members of the draw bar when the draw bar has been moved from a fully retracted position in the extension direction by a second set distance, the arrangement being such that, in use, continued movement of the draw bar in the extension direction beyond the second set distance causes the second guide bar to be drawn forward in the extension direction by the pull tabs of the second guide bar.
16. A roller blind assembly as claimed in any one of the preceding claims, wherein the roller blind assembly is configured for use in a vehicle, especially a construction vehicle.
17. A roller blind assembly as claimed in claim 16, wherein the roller blind assembly is configured for use as shade for a sunroof of the vehicle
18. A vehicle comprising a roller blind as claimed in any one of the preceding claims.
19. A vehicle as claimed in claim 18, wherein the vehicle is a construction vehicle.
20. A vehicle as claimed in claim 18 or claim 19, wherein the vehicle has a sunroof and the blind assembly is configured as a screen for the sunroof