AU760547B2 - A blind control mechanism - Google Patents

Description

2 A BLIND CONTROL MECHANISM This invention relates to blinds and similar arrangements for extending across a window or the like. The invention is particularly concerned with such blinds that are selectively operable between closed and open conditions. It will be convenient to hereinafter describe the invention in relation to roller blinds however it should be appreciated that the invention has wider application.

Roller blinds generally include a length of flexible material wound onto a cylinder with the roller blind operating between its open and closed conditions by rotation of the cylinder causing extension and retraction of the flexible material. Roller blinds generally include a mechanism for facilitating such operation. One type of mechanism may be descried as a spring roller. This type of mechanism uses a biasing spring to counterbalance the weight of the 15 extended flexible material and a latch to stop unauthorised retraction of the material. The material can be retracted by rotating the cylinder ,in an extending direction, to a position that disengages the latch, and rotating the cylinder, in a retracting direction, at a speed that will not permit the latch to re-engage. This speed may be dictated by the release of the energy stored in the spring alone or 20 as altered by manual intervention. This type of mechanism can be difficult to operate as the latch is controlled by rotation of the blind cylinder and what is a suitable speed to avoid re-engagement of the latch is variable. Furthermore the :spring may retract the material a such a speed that the blind over rotates past its retracted position, which will affect the tension of the spring.

Another type of roller mechanism, which may be described as a clutch roller, is the subject of Australian patent 667615. The clutch roller includes a drive member which is operable to cause rotation of a driven member. The driven member cannot rotate unless it is rotated by the drive member. This is achieved by the driven member engaging a helical spring which grips a fixed shaft when a rotating force is applied directly to the driven member. The drive member is operable to release the grip of the helical spring and thereby cause rotation of the driven member, which is connected to the blind cylinder.

Operation of the blind therefore requires the user to overcome the frictional W:\KATHY\TJCSPECI\CAP OF P02410 BLINDDOC 3 resistance of the helical springs. Furthermore, the clutch roller does not include any means to counter balance the weight of the extended material. However, operation of the blind using the clutch roller mechanism is relatively accurate.

It is an object of this invention to provide a mechanism that is relatively easy to operate. It is a further object of this invention to provide such a mechanism that accommodates, at least to some extent, the weight of the extended material.

A blind control mechanism according to this invention includes a rotatable cylinder, manually operable drive means connected to the cylinder and being operable to rotate the cylinder in either a blind extending direction or a blind retracting direction, biasing means connected to said cylinder being responsive to rotation of the cylinder in a blind extending direction to store energy and being responsive to rotation of said cylinder in a blind retracting direction to release said stored energy and thereby apply a turning force to the cylinder, said turning force acting in the blind retracting direction, and clutch means acting between said cylinder and a relatively fixed member so as to at least resist rotation of said cylinder under the influence of said release of stored energy alone, said clutch means being responsive to operation of said drive 20 means to adopt at least a partially disengaged condition such as to permit rotation of said cylinder by operation of said drive means Preferably the biasing means is a biasing spring however this is not essential, as clearly other forms of biasing means may also be suitable. Where the biasing means is a biasing spring it is preferred that one end of the biasing spring engage the blind cylinder whilst the other end is associated with the relatively fixed member. This arrangement allows the biasing spring to store and release the energy resulting from with the rotation of the rotatable cylinder.

It is preferred that the biasing spring be associated with the relatively fixed member via an interconnecting means. It is further preferred that the interconnecting means be in the form of a connecting member having a distal portion attached to the biasing means and a proximal portion attached to the relatively fixed member. Where the biasing means is in the form of a biasing W:\KATH\Tjc\SPECI\AP OF P02410 BLINDMOC 4 spring it is preferred that the distal portion of the connecting member have a frusto conical portion to receive the proximal end of the spring, however this is not essential. It is preferred but not essential that the frusto conical portion include a thread to receive the spring. In this preferred arrangement it is intended that the spring be wound onto the threaded frusto conical portion, however other methods of attaching the distal portion of the connecting member to the proximal end of the spring are clearly possible.

The proximal portion of the connecting member may be attached to the relatively fixed member any appropriate manner. It is preferred that the connecting member snap engage the relatively fixed member, but this is not essential. It is also preferred that the proximal portion of the connecting member include at least one flange that can engage at least one surface of a Oil slot in the relatively fixed member. The at least one flange restricts the 15 connecting member from rotating relative to the relatively fixed member which fixes the proximal end of the spring from rotating. This manner of fixing the connecting member from rotating is not essential and alternatives are clearly possible.

20 The invention will be hereinafter described by reference to the accompanying drawings which show a preferred embodiment of the invention. The particularity of the related description is not to be understood as superseding the generality of the broad identification of the invention as given in the claims of this specification.

Figure 1 is an exploded view of a blind control mechanism according to one preferred embodiment of the invention.

Figure 2 is a cross-sectional illustration of the blind control mechanism according to the preferred embodiment of the invention.

In the preferred arrangement shown, a rotatable cylinder 1 is adapted to carry blind material (not shown) so that the material is wound onto the cylinder 1 when retracted, and is wound off the cylinder 1 when extended. The cylinder 1 WAKATHYTJCSPECACAP OF P02410 BLINDMOC is connected to biasing means 2 as hereinafter described, and is also connected to drive means 3 which is manually operable to rotate the cylinder 1 in either a blind extending direction or a blind retracting direction. The biasing means 2 is responsive to operation of the drive means 3 so as to either store energy, or release stored energy, according to circumstances as hereinafter described. In the latter case, the biasing means 12 applies a force to the cylinder 1 (by way of the released energy) so as to urge the cylinder 1 in the blind retracting direction.

The drive means 3 is rotatably mounted on a relatively fixed member, preferably a shaft 4 and includes a drive member 5 and a driven member 6. Each of those members 4, 5, 6 forms part of clutch means 7 as hereinafter described. The 0 driven member 6 is preferably assembled on a projecting cylindrical barrel part of the drive member 5 so that the drive and driven members 5, 6 are capable of 15 limited relative rotation in a manner described in patent specification 667615.

The drive means 3 and the rotatable cylinder 1, form respective parts of a rotatable assembly 9 supported at one end by the shaft 4 and supported at the other end by appropriate means (not shown). The biasing means 2 acts between the rotatable assembly 9 and the shaft 4 as hereinafter described.

*o o The clutch means 7 functions to resist rotation of the driven member 6. In the preferred arrangement shown in the drawings, the degree of that resistance is reduced by operation of the drive means 3. In circumstances where the drive means 3 is not being operated, it is preferred that the clutch means 7 applies sufficient resistance to rotation of the driven member 6 to prevent rotation of the assembly 9 under the influence of the biasing means 2 alone. That is, energy stored in the biasing means 2 cannot apply a turning force to the assembly 9 of sufficient magnitude to overcome the resistance of the clutch means 7. On the other hand, operation of the drive means 3 such as to rotate the assembly 9 in the blind retracting direction, permits the release of stored energy from the biasing means 2 so that rotation of the assembly 9 in the blind retracting direction is assisted by a turning force applied to the assembly 9 by the biasing means 2.

W:(KATHYTJCSPECFCAP OF PQ2410 BLIND.DOC 6 In the particular arrangement shown in the accompanying drawings, the cylinder 1 is in the form of an open ended tube, and the drive means 3 is connected to one end of that tube. The drive means 3 in the arrangement shown, in particular the drive member 5 and a driven member 6, is of generally tubular form. The driven member 6 is mounted on the tubular barrel portion 8 of the drive member 5 so as to be capable of a limited degree of rotation relative to the member 5. An end portion of the cylinder 1 is located over a tubular barrel portion of the driven member 6, and is connected to that member in a manner such that the cylinder 1 is held against rotation relative to the driven member 6.

Rotation of the cylinder 1 is thereby controlled by rotation of the drive means 3 relative to the fixed support shaft 4.

Any suitable drive mean 3 could be employed. In the arrangement shown, the drive member 5 is of a generally known form, and includes a wheel section 8 15 around which a control cord (not shown) is looped. The cord, and its manner of cooperation with the wheel section, is known. The arrangement is such that the cylinder 1 is turned in a blind extending direction when the section of cord at one side of the wheel section 8 is pulled, and the cylinder 1 is turned in a blind retracting direction when the section of cord at the other side of the wheel section 8 is pulled. The driven member 6 rotates with the drive member 5 as S.hereinafter explained.

The clutch means 7 can be of any suitable form, but preferably includes a S"friction-type clutch. In the particular arrangement shown, the clutch is generally as described in Australian patent 667616, and includes at least one, but preferably more than one, helical spring 10 mounted on the fixed shaft 4. Each spring 10 has a laterally projecting finger 11 at each end, and as shown by Figure 1, those fingers are spaced apart in the circumferential direction of the spring 10. The spring 10 clamps firmly on the shaft 4 when the fingers 11 are moved so as to increase the circumferential distance between them. On the other hand, a decrease in that distance increases the diameter of the spring and thereby reduces, or removes entirely, the gripping force between the spring and the shaft 4.

W:VXATHYTJC\SPECI\CAP OF PQ2410 BLINDOOC 7 In the particular arrangement shown, the spring fingers 11 extend through a slot 12 formed longitudinally through the wall of the barrel section of the drive member 5. Each finger 11 is therefore engageable with a respective longitudinal edge 13, 14 of the slot 12. A longitudinally extending rib 15 formed on the barrel section of the driven member 6 is also positioned within the slot 12, and is located between the spring fingers 11. The width of the rib 15 is preferably such that the driven member 6 can rotate to a limited extent relative to the drive member 5 for a reason hereinafter made clear.

The biasing means 2 preferably includes a biasing spring 16. In the example arrangement shown, the spring 16 is in the form of an elongate cylinder and is mounted on a support rod or tube 17. One end of the tube 22 engages a S"cylinder engaging member 18 and the other end is connected to interconnecting means 19. The interconnecting means 19 includes a frusto-conical section 15 and a mounting stem 21 by means of which the interconnecting means 20, and the tube 20, are connected to the shaft 5. It is preferred that the mounting stem 21 snap engages with the shaft 4, but other forms of releasable attachment could be used. It is also preferred that the stem 21 cooperates with the shaft 4 in a manner such as to be held against relative rotation.

S An end portion 22 of the biasing spring 16 is tightly wound onto the frustoconical section 20 so as to be held against relative rotation. The opposite end :of the spring 16 is attached to the cylinder engaging member 18 so as to rotate with the cylinder 1. The arrangement is such that rotation of the cylinder 1 in the blind extending direction causes the spring 16 to be tightened or tensioned, and thereby energised. That is, releasable energy is stored in the spring as it is tensioned. Rotation of the cylinder 1 in the blind retracting direction unwinds the spring 16 and thereby permits the release of stored energy such that the spring 16 can apply a turning force to the cylinder 1 in the blind retracting direction of rotation.

Assuming the blind material (not shown) is fully wound upon the cylinder 1, rotation of the cylinder 1 in the blind extending direction will cause the blind to be extended. Such rotation is achieved by pulling on the appropriate portion of W:\KATHY\TJC\SPECICAP OF P02410 BLIND.DOC 8 the control cord (not shown) so as to cause the drive member 5 to rotate in the appropriate direction. The initial part of that movement will, in most cases, be movement relative to the driven member 6, and will cause the fingers 11 of the or each spring 10 to be closer together. As a result of that movement, the springs 10 loosen their grip on the shaft 4.

Following the initial take-up movement of the drive member 5, the drive member presses against a side of the rib 15 of the driven member 6, through the intermediary of one group of spring fingers 11, and thereafter pushes the driven member 6 so that it rotates with the drive member 5. Such rotation of the driven member 6 causes the spring 16 to be tightened or tensioned as described above.

.:oo.i o If the drive member 5 is subsequently rotated in the blind retracting direction, the same interaction as described above occurs between the drive member spring 10, shaft 4, and driven member 6. On this occasion however, the spring 16 is caused to unwind and is thereby allowed to release stored energy.

Because of the connection between the spring 16 and the cylinder 1, such release of energy results in a turning force being applied to the cylinder 1, and that force acts in the blind retracting direction. Since the cylinder 1 is nonrotatably connected to the driven member 6, it follows that release of the stored energy reduces the magnitude of the manual effort required to turn the drive member 5 as it accommodates, at least to some extent the weight of the material.

Various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention as defined by the appended claims.

W:U(ATHykTJC\SPECI\CAP OF P02410 BLIND.DOC

Claims (7)

1. A blind control mechanism for controlling extension and retraction of a blind, the mechanism including a rotatable cylinder, manually operable drive means connected to the cylinder and being operable to rotate the cylinder in either a blind extending direction or a blind retracting direction, the biasing means connected to said cylinder being responsive to rotation of the cylinder in a blind extending direction to store energy and being responsive to rotation of said cylinder in a blind retracting direction to release said stored energy and thereby apply a turning force to the cylinder, said turning force acting in the blind retracting direction, and clutch means acting between said cylinder and a relatively fixed member so as to at least resist rotation of said cylinder under the influence of said release of stored energy alone, said clutch means being responsive to operation of said drive means to adopt at least a partially 15 disengaged condition such as to permit rotation of said cylinder by operation of said drive means.

2. A blind control mechanism according to claim 1, wherein the biasing means is a biasing spring one end of which engages the blind cylinder whilst 20 the other end is associated with the relatively fixed member whereby rotation of the blind cylinder in the blind extending direction and blind retracting direction allows the biasing spring to store and release energy respectively.

S3. A blind control mechanism according to claim 2, including a connecting member for associating the biasing spring with the relatively fixed member, the connecting member having a distal portion attached to the biasing means and a proximal portion attached to the relatively fixed member.

4. A blind control mechanism according to claim 3, wherein the distal portion of the interconnecting member includes a frusto-conical portion to receive a proximal end of the biasing spring, the frusto-conical portion including a thread to receive the biasing spring.

W:K(ATHYTJC\SPECI\CAP OF PQ2410 BLIND.DOC A blind control mechanism according to claim 3 or 4, wherein the proximal portion includes means for snap engagement of the relatively fixed member.

6. A blind control mechanism according to any one of claims 3 to 5, wherein a proximal portion includes at least one flange for engaging at least one surface of a slot in the relatively fixed member to restrict the connecting member from rotating relative to the fixed member.

7. A blind control mechanism substantially as hereinbefore described and illustrated. S. S DATED: 25 August 2000 PHILLIPS ORMONDE FITZPATRICK Attorneys for: DAMORGOLD PTY LTD 20 a 7 o W:AKATHY\TJC\SPECI\CAP OF PQ2410 BLIND.DOC