Roller blind assembly, drive unit and idle end unit

Abstract

A roller blind assembly 1 with a roller blind 2, a drive unit 4 at one end and an idle end unit 5 at a second end of the roller 3. The drive unit 4 (or sidewinder) includes a first extendable shaft wi

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. 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 extendable shaft (6) provided with a friction head (7), and spring means (8) which acts to urge the first extendable shaft towards an extended position. The idle end unit (5) includes a rotatable drive wheel (30) and a second extendable shaft (26) provided with a friction head (27), the arrangement being such that, in use, rotation of the drive wheel causes the shaft to extend to apply pressure on a surface of the window opening. The second extendable shaft (26) is preferably unsprung. 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 general view, axially sectioned, of a modified form of extendable shaft and friction head for use in the roller blind assembly. 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 disc-shaped 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 is formed with concentric friction rings 9, although the end face could have other forms, such as a resilient rubber pad for example. 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 disc-shaped friction head 27. The end face of friction head 27 remote from the body of the unit 5 is formed with concentric friction rings 29. As noted above however, the end face could have other forms such as a resilient pad. 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. Fig. 6 shows a modification to the friction heads 7 and 27 in which the head is rectangular rather than circular. This has the advantage that edges of the friction head may abut the top and / or rear surface of the opening to provide more positive location of the blind during fixing. 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 extendable shaft (6) provided with a friction head (7), and spring means (8) which acts to urge the first extendable shaft towards an extended position;wherein the idle end unit (5) includes a rotatable drive wheel (30) and a second extendable shaft (26) provided with a friction head (27), the arrangement being such that, in use, rotation of the drive wheel causes the shaft to extend to apply pressure on a surface of the window opening.

2. The roller blind assembly of claim 1 wherein the drive unit (4) includes a cover (10) having a cylindrical projection (11) and the first shaft (6) is slidably received within the cylindrical projection.

3. The roller blind assembly of claim 2 wherein the cylindrical projection (11) is stepped (12) forming an abutment for the spring means (8).end of the cylindrical projection (11) is formed with spring fingers (13) which have external locating shoulders (14).

5. The roller blind assembly of claim 2, 3 or 4 wherein an inner end of the shaft (6) extends beyond the cylindrical projection (11) and carries a retaining ring (15).

6. The roller blind assembly of claim 2, 3, 4 or 5 wherein the cover (10) contains a pulley (18) which is integrally formed with a tubular spigot (19) which is rotatably located about the cylindrical projection (11).

7. The roller blind assembly of claim 6 wherein a drive member (20) is located about the tubular spigot (19) for engagement with the roller (3).

8. The roller blind assembly of claims 4 and 7 wherein the drive member (20) is retained by the spring fingers (13).

9. The roller blind assembly of claim 7 or 8 wherein a thrust bearing (22) is axially interposed between the tubular spigot (19) and an inner end of the drive member (20).

10. The roller blind assembly of claim wherein the idle end unit (5) includes a rotatable drive wheel (30) having a cylindrical projection (31) which is internally screw-threaded.externally screw-threaded screw cylinder (39) is located about the second shaft (26) and screw-threadedly engaged with the cylindrical projection (31).

12. The roller blind assembly of claim 11 wherein the screw cylinder (39) has an internal annular rib (45) which co-operates with an annular shoulder (46) on the second shaft (26) to extend the second shaft.

13. The roller blind assembly of claim 10, 11 or 12 wherein a drive member (40) is located about the cylindrical projection (31) for engagement with the roller (3).

14. The roller blind assembly of claim 13 wherein the drive member (40) has an annular end wall (42) which is closed by a hollow axial protrusion (43) to receive the second shaft (26).

15. The roller blind assembly of claim 14 wherein the second shaft (26) is provided with at least one rebated sealing ring (53, 54) which frictionably engages the inside of the axial protrusion (43).

16. The roller blind assembly of claim 14 or 15 wherein a thrust bearing (52) is axially interposed between the annular end wall (42) and the inner end of the cylindrical projection (31).

17. The roller blind assembly of any preceding claim wherein the second extendable shaft (26) is unsprung.

18. The roller blind assembly of any preceding claim wherein the friction heads (7, 27) are of substantially rectangular profile.

19. The drive unit of any of claims 1 to 9.

20. The idle end unit of any of claims 12 to 17.

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