Roller blind assembly mountable by friction

Abstract

A roller blind assembly is disclosed which is mountable by friction. It has a sheet of shade material on a roller, a drive unit with a first shaft 6, 26 with a friction head, and an idle unit with a s

Description

TECHNICAL FIELD OF THE INVENTION This invention relates to roller blind assemblies which include a drive unit and an idle end unit. BACKGROUND In a well known form of roller blind assembly a fabric blind or shade is wound on a roller which is normally, but not always, a tube. One end of the roller has a drive unit known as a sidewinder by which the roller may be manually rotated using a cord, ball chain or wand. The opposite end of the roller is provided with an idle end unit. The blind may be mounted in a window opening by engaging the sidewinder and idle end unit with metal or plastic brackets which are typically fixed in the opening using screws. Fixing the brackets securely and in the correct positions at the sides of the opining or on a window frame requires a certain amount of skill, and inevitably causes damage to the surfaces to which the brackets are attached. Roller blinds are known which can be secured using nothing more than friction applied to opposite sides of the window opening, but these have not been particularly successful, mainly because they are awkward for the average person to handle and secure. In particular, it is not easy to accurately position the assembly and hold it in place at the same time as the assembly is being secured. SUMMARY OF THE INVENTION When viewed from one aspect the present invention proposes a roller blind assembly which is mountable by friction within a window opening. The assembly includes a sheet of shade material (2) wound on a roller (3), a drive unit (4) at one end for rotatably driving the roller, and an idle end unit (5) at a second end of the roller. The drive unit (4) includes a first shaft (6) provided with a friction head (7), the idle end unit (5) includes a second shaft (26) provided with a friction head (27), and at least one of the first and second shafts is extendable relative to the roller. At least one of the friction heads (7, 27) has a non-circular profile. BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a general view of a roller blind assembly which is mountable by friction; Figure 2 is a general view of a drive unit which is attached to one end of the roller blind; Figure 3 is a longitudinal section through the drive unit; Figure 4 is a general view of an idle end unit which is attached to the opposite end of the roller blind; Figure 5 is a longitudinal section through the idle end unit; Figure 6 is a detailed general view, axially sectioned, of an extendable shaft and friction head for use in the roller blind assembly; Figures 7-13 show seven different configurations of the friction head. DETAILED DESCRIPTION OF THE DRAWINGS Referring firstly to Fig. 1, the roller blind assembly 1 which is mountable by friction within a window opening includes a sheet of shade material 2 which is wound on a roller 3. A drive unit 4 and an idle end unit 5 are secured at opposite ends of the roller. The drive unit 4 is used for rotatably driving the roller. In the present embodiment the drive unit is of the kind known as a sidewinder which enables the shade material to be manually wound and unwound using a ball chain 16 looped around the sidewinder, although other means of rotation can be used such as a friction cord or, as described in GB 2 486 555-A, a rotatable wand. Drive units which incorporate an electric motor may also be used. Referring to Fig. 2, the sidewinder 4 includes a first telescopically extendable shaft 6 which projects from the body of the sidewinder and is provided with a friction head 7. A compression spring 8 is coiled around the shaft 6 and acts to urge the shaft towards an extended position, as shown. The end face of friction head 7 which is remote from the body of the sidewinder 4 may be formed with concentric friction rings 9, as shown. Turning to Fig. 3, it can be seen that the sidewinder comprises a moulded plastics cover 10 which is formed with an internal cylindrical projection 11. This projection slidably receives the shaft 6 and compression spring 8 and is stepped at 12 forming an abutment for the spring 8. The inner end of the projection 11 is formed with spring fingers 13 which have external locating shoulders 14 (see below). The inner end of the shaft 6 extends beyond the cylindrical projection 11 to carry a retaining ring 15, also seen in Fig. 2. It will thus be appreciated that the spring 8 acts between the friction head 7 and the abutment 12 to urge the shaft towards the extended position which is limited by the retaining ring 15. The shaft 6 is keyed to the inside of the cylindrical projection 11, e.g. by splines or by having a hexagonal or other non-circular cross-section. The cover 10 and projection 11 are thereby non-rotatably fixed in relation to the friction head 7. The cover 10 contains a pulley 18 which is externally profiled to engage the ball chain 16 (Fig. 1) thereby allowing the pulley to be rotated within the cover 10. The pulley 18 is integrally formed with a tubular spigot 19 which is rotatably located about the projection 11. A drive member 20 is, in turn, rotatably located about the tubular spigot 19 retained by the spring fingers 13. As can be seen in Fig. 2, the drive member 20 has external splines 21 allowing the spigot to be non-rotatably fixed within the roller 3. A thrust bearing 22 is axially interposed between the end of the spigot 19 and the inner end of the drive member 20. Relative rotation between the drive member 20 and the fixed parts of the drive unit (6, 7, 10 and 11) is controlled as described in GB 2 486 555-A. The cylindrical projection 11 carries a clutch member in the form of a helical coil spring 23 which encircles the projection for a number of turns, the inside diameter of the coil spring being slightly less than the outside diameter of the projection. The ends of the spring are out-turned to form a pair of circumferentially spaced projecting drive tangs. The tubular spigot 19 contains an axial slot in which the drive tangs are received, and the drive member 20 has an internal axial rib which is located between the tangs. Rotation of the pulley 18 in either direction causes the tangs to contact the sides of the slot which unwinds the spring causing it to release its grip on the projection 11. Drive is transmitted to the drive member via the internal rib, allowing the blind to be wound onto or unwound from the roller. Rotation of the projection 11 other than by the pulley, e.g. under the weight of the blind, causes the rib to engage one or other of the tangs which winds up the spring causing it to tighten its grip on the projection 11, thereby resisting further rotation of the roller. Referring now to Fig. 4, the idle end unit 5 includes a second telescopically extendable shaft 26, which is unsprung. This shaft projects from the body of the unit 5 and is provided with a friction head 27. The end face of friction head 27 remote from the body of the unit 5 may be formed with concentric friction rings 29. The idle end unit also includes a rotatable drive wheel 30 which has a number of teeth or a similar gripping profile around its periphery. Referring now to Fig. 5, the drive wheel 30 is integrally formed with a cylindrical projection 31 which extends into the body of the unit 5 and is internally screw-threaded. An externally screw-threaded screw cylinder 39 is located about the shaft 26 to screw-threadedly engage the projection 31. External to the projection 31 a drive member 40 is located about the projection and, as can be seen in Fig. 4, the drive member has external splines 41 which allow the spigot to be non-rotatably fixed within the roller 3. The inner end of the drive member 40 includes an annular end wall 42 which is closed by a hollow integral axial protrusion 43. A thrust bearing 52 is axially interposed between the end wall 42 and the inner end of the cylindrical projection 31. The shaft 26 is preferably profiled, e.g. with splines, a hexagonal cross-section or other non-circular profile, to be a non-rotational sliding fit within the screw cylinder 39. The inner end of the screw cylinder has an internal annular rib 45 which co-operates with an annular shoulder 46 on the shaft 26 such that, when the shaft is fully inserted into the idle end unit, the rib 45 engages the shoulder 46 to extend the shaft. The inner end of the shaft, remote from the friction head 27, is provided with at least one, and preferably two, rebated sealing rings 53 and 54 which frictionably engage the inside of the protrusion 43. The rings therefore retain the shaft within the idle end unit whilst ensuring that shaft can be extended when driven by the screw cylinder 39. When the screw cylinder 39 is fully screwed into the projection 31 as shown, and with the shaft 26 fully inserted, the friction head 27 is snugly received within the rotatable drive wheel 30. As the drive wheel is manually rotated relative to the drive member 40 the screw cylinder 39 will be gradually extended along with the shaft 26 and friction head 27. If the shaft and friction head are partially extended as shown, they will only commence further outward movement when engaged by the screw cylinder 39. To mount the roller blind assembly in a window opening the width of the opening can be measured and the second shaft 26 pre-extended by a sufficient distance that, with the first shaft 6 depressed against its spring loading, the distance between the friction heads 7 and 27 is slightly less than the width of the opening. The first head 7 is then placed against one side of the opening and, applying manual axial pressure to the roller blind assembly, the head is telescoped into the sidewinder until the second friction head 27 opposes the opposite side of the opening. Since both friction heads now engage opposite sides of the opening the pressure on the first friction head can be relaxed. To achieve secure permanent fixation the drive wheel 30 is rotated causing the screw cylinder 39 to further advance the second friction head 27. The outward pressure will therefore increase further as the spring 8 is compressed. Once the pressure exerted by the friction heads 7 and 27 is sufficient to securely hold the assembly within the window opening no further rotation of the drive wheel is necessary. It will be appreciated that since the friction head 7 of the sidewinder is engaged with the window opening first, the depending ball chain, cord or wand will not impede manipulation of the assembly during adjustment of the drive wheel. If a motorised drive unit is used the extra weight of the motor is supported by the friction of the first head while the assembly is being secured. In the preceding drawings the friction heads 7 and 27 are represented as conventional discs. Fig. 6 shows, in axial cross-section, one of the friction heads 7, 27 in greater detail. Both of the friction heads may be of of the same size and profile. The telescopically extendable shafts 6 and 26 which project from the body of the sidewinder 4 and idle end unit 5 are each provided with a respective friction head 7, 27 with a non-circular profile. The end face of each friction head which is remote from the shaft 6, 26 is shown with concentric friction rings 9, 29 although the end face could have other forms, such as a resilient rubber pad for example. Referring to Fig. 7, the friction head 7 has four straight edges 60-63 of equal length arranged in a substantially square profile. The position of the central axis of the respective shaft 6 is indicated by the centre of cross A, which is located at the centre of the head 7. With this arrangement two adjacent edges, e.g. 61-62 or 61-60, may abut substantially flat top and rear faces of the window opening to provide positive location of the blind assembly during fixing. Indeed, positioning of the blind is made easier even if only one of the edges 60-63 abuts a surface of the opening. In this first example the square friction head is symmetrical about two mutually perpendicular axes and the distance B between each of the sides 60-63 and the axis A is the same. However, the friction heads are not necessarily square. Fig.s 8-11 show alternative shapes which can also provide positive location between the top and / or rear faces of a window opening. In Fig. 8 the friction head 7 is of cruciform shape with four arms ending in four straight edges 64-67 of equal length each arranged perpendicular to the adjacent edges. The axis of the respective shaft is again indicated by the cross A. The friction head is symmetrical about two perpendicular axes and the distance C between each of the edges 64-67 and the axis A is the same. As before, two adjacent edges 64-67 may abut the top and / or rear faces of the window opening to provide positive location of the blind during fixing. Fig. 9 shows a hexagonal friction head 7 with six straight edges 68-73 of equal length. The axis of the shaft is again indicated by the cross A. The friction head is symmetrical about perpendicular axes and the distance D between each of the six edges and the axis A is the same. In this example only one of the edges 68-73 may abut the perpendicular top or rear faces of the window opening to provide positive location during fixing. However, the apex of two adjacent edges may still abut another side of the window at the same time. This may be particularly useful in the case of window openings with irregular or non-perpendicular faces. Another regular shape is shown in Fig. 10 in the form of an octagonal friction head 7 with eight straight edges 74-81 of equal length. The axis of the shaft is again indicated bythecrossA. The friction head is symmetrical about perpendicular axes and the distance E between each of the edges and the axis A is the same. In this example alternate edges are arranged perpendicularly, two of which may abut the top and / or rear faces of the window opening to provide positive location of the blind during fixing. As with the hexagonal friction head, it is not necessary for all of the edges which abut the faces of the window opening to be straight. Fig. 11 shows a regular four-pointed star-shaped friction head 7 in which two adjacent points can abut two perpendicular faces of the opening and still provide positive location during fitting of the blind. The axis of the shaft is indicated by the cross A and the friction head is symmetrical about perpendicular axes. Also, the distance F between each face of the opening and the axis A is the same. In some installations it may be desirable for the blind to have different spacing from the top and rear faces of a window opening. This may be achieved by means of the rectangular friction head of Fig. 12 in which two opposite edges 82 and 84 are longer than the other two edges 83 and 85. The axis of the shaft is indicated by cross A. The friction head is symmetrical about perpendicular axes but the distance G between edges 82 and 84 and the axis A is shorter than the distance H between edges 83 and 85 and Axis A. Fig. 13 shows yet another configuration of friction head 7 which is of cruciform shape with four arms ending in four straight edges 86-89 of equal length each extending perpendicular to the adjacent edges. The axis of the shaft is indicated by cross A, but the friction head is asymmetrical and the distances I-L between each of the edges 86-89 and the axis A are all different. As before, two adjacent edges 64-67 may abut the top and / or rear faces of the window opening to provide positive location of the blind during fixing, but in this case the friction head provides a choice of four different spacings. In all of the above examples the friction heads 7 and 27 would be of the same size and profile. However, in the case of non-symmetrical heads one head would be a mirror image of the other. Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

1. A roller blind assembly which is mountable by friction within a window opening:- a sheet of shade material (2) wound on a roller (3);- a drive unit (4) at one end for rotatably driving the roller;- an idle end unit (5) at a second end of the roller;wherein the drive unit (4) includes a first shaft (6) provided with a friction head (7);wherein the idle end unit (5) includes a second shaft (26) provided with a friction head (27);wherein at least one of the first and second shafts is extendable relative to the roller;wherein at least one of the friction heads (7, 27) has a non-circular profile.

2. The roller blind assembly of claim 1 wherein the head (7) has at least two mutually perpendicular edges (61-62, 61-60).

3. The roller blind assembly of claim 1 or 2 wherein the shaft (6) has a central axis (A) which is located at the centre of the friction head.

4. The roller blind assembly of any preceding claim wherein and the distance (B) between each of the sides (60-63) and the central axis (A) of the shaft (6) is the same.

5. The roller blind assembly of any preceding claim wherein the friction head (7) is symmetrical about two mutually perpendicular axes.

6. The roller blind assembly of any preceding claim wherein the friction head has four straight edges (60-63) of equal length arranged in a substantially square profile.

7. The roller blind assembly of any of claims 1 to 5 wherein the friction head (7) is of cruciform shape with four arms ending in four straight edges (64-67) of equal length.

8. The roller blind assembly of any of claims 1 to 5 wherein the friction head (7) hexagonal with six straight edges (68-73) of equal length.

9. The roller blind assembly of any of claims 1 to 5 wherein the friction head (7) is octagonal with eight straight edges (74-81) of equal length.

10. The roller blind assembly of any of claims 1 to 5 wherein the friction head (7) is star-shaped.

11. The roller blind assembly of claim 10 wherein the star-shaped friction head (7) has four points.

12. The roller blind assembly of claim 1 or 2 wherein the friction head (7) is asymmetrical.

13. The roller blind assembly of claim 12 wherein and the distances (I-L) between at least two of the edges (86-89) and the central axis (A) of the shaft (6) are different.

14. The roller blind assembly of claim 12 or 13 wherein the friction head is rectangular with two opposite edges (82 and 84) which are longer than the other two edges (83 and 85).

15. The roller blind assembly of claim 12 or 13 wherein the friction head (7) is of cruciform shape with four arms of unequal length.

16. The roller blind assembly of any preceding claim wherein both of the friction heads (7, 27) have substantially identical non-circular profiles.

17. The roller blind assembly of any preceding claim wherein one of the friction heads (7, 27) is a mirror image of the other.

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