Operating mechanism for a roller blind or roman blind

Abstract

Operating mechanism for a blind, comprising a tube provided with a drive mechanism (7) and a clamping mechanism (9), wherein the drive mechanism (7) comprises a first carriage (10) and a drive wheel (12) connected to the first carriage (10), whereby the drive mechanism (7) is provided with a first attachment element (4), whereby the clamping mechanism (9) comprises a second carriage (19) and an idler wheel (20) connected to the second carriage (19), whereby the clamping mechanism (9) is provided with a second attachment element (5) provided with a second brake surface (22) that makes contact with a second contact surface (21) on the idler wheel (20), whereby the clamping mechanism (9) is provided with a spring (23) which pushes away the idler wheel (20) from the second carriage (19), such that the spring (23) pushes the brake surfaces (16,22) and contact surfaces (15,21) against each other.

Description

[0001] The present invention relates to an operating mechanism for a roller blind or Roman blind.

[0002] In particular, the invention is intended for opening and closing a roller blind, a Roman blind, an awning with horizontal slats or the like.

[0003] Traditionally, such roller blind or Roman blind is rolled up or unrolled from a rotatable tube, which at its free ends is suspended on bearings between two attachment elements.

[0004] Traditional operating mechanisms for a roller blind or Roman blind work with a chain and a sprocket, which is mounted at one free end of the tube. The place where the sprocket is mounted is referred to in technical language as the drive side, the other side of the tube, opposite the drive side is referred to as the idler side.

[0005] Usually, the operating mechanism also contains a gear mechanism to transfer the rotation of the sprocket to the tube. Such gear mechanism is for example a planetary gear mechanism, such that big forces can be transferred between the sprocket and the tube without any problem.

[0006] Traditionally the operating mechanism also comprises a locking mechanism, for example a ratchet mechanism, to let the roller blind or Roman blind hang at the desired height.

[0007] Said known operating mechanisms have the disadvantage of not being very visually attractive because the drive side and the idler side are not symmetrical. Usually, the drive side, where the sprocket and the gear mechanism are mounted, take up much more space than the idler side.

[0008] Another disadvantage is that the operation with chain, sprocket and gear mechanism is very noisy. Raising and lowering the roller blind or Roman blind is accompanied by a rattling sound, especially if the mechanism is poorly maintained or shows wear and tear.

[0009] Another disadvantage is that the height of the roller blind or Roman blind is only adjustable in steps. More specifically, this is because the height of every step depends on the number of teeth of the sprocket and of the gear mechanism.

[0010] Yet another disadvantage of the known operating mechanisms is that the operating force of said mechanisms is not adjustable. The operating force varies with the weight and therefore the width of the blind and also with the thickness and composition of the chosen fabric. In case of bad maintenance or worn out mechanisms more operating force is often required, which may even result in failure of the mechanism.

[0011] The known operating mechanisms with planetary gear transmissions are complex, maintenance sensitive and not very durable. Indeed, often the gear transmissions are made of plastic, which are nonetheless subjected to very high forces during operation. Moreover, often said mechanisms are mounted behind a window such that they can get very hot. Consequently the components of the mechanism may expand and block the mechanism or cause the components to age faster and render the mechanism unusable.

[0012] The purpose of the present invention is to provide a solution to the aforementioned and other disadvantages.

[0013] To this end, the invention relates to an operating mechanism for a roller blind or Roman blind, comprising a tube on which the blind can be rolled up and unrolled, whereby a drive side of the tube is provided with a drive mechanism and an idler side of the tube is provided with a clamping mechanism, whereby the drive mechanism comprises a first torque transmitting carriage to be applied at least partly in an open end of the drive side of the tube and a drive wheel that is connected to the first carriage in a torque transmitting manner, whereby the drive wheel is provided with a cord or the like to be able to drive the drive wheel, whereby the drive mechanism is further provided with a first attachment element for attaching the operating mechanism on the level of a window or the like, whereby the clamping mechanism comprises a second torque transmitting carriage to be applied at least partly in an open end of the idler side of the tube, an idler wheel that is connected to the second carriage in a torque transmitting manner, whereby the clamping mechanism is further provided with a second attachment element for attaching the operating mechanism on the level of the window or the like, said second attachment element being provided with a second brake surface that makes contact with a corresponding second contact surface provided to this end on the idler wheel, whereby the clamping mechanism is further provided with a tensioned spring that is applied between the second carriage and the idler wheel and which pushes the idler wheel in an axial direction away from the second carriage, all this such that after assembly the spring pushes the brake surfaces and contact surfaces against each other in an axial direction.

[0014] A major advantage of an operating mechanism according to the invention is that a very robust and user-friendly mechanism is obtained with a minimum of components. The operating mechanism according to the invention is therefore less maintenance sensitive and less prone to failure.

[0015] As the operating mechanism according to the invention does not use a sprocket and gear mechanism, but a drive wheel and a cord, the height of the blind is continuously adjustable and not in steps.

[0016] Obviously, thanks to the absence of the gear mechanism, the operating mechanism according to the invention, is many times quieter during operation than traditional operating mechanisms.

[0017] The spring that pushes the respective contact surfaces and brake surfaces against each other acts as a locking mechanism to keep the blind at the desired height.

[0018] Another advantage is that the operating force of the operating mechanism also depends on the spring constant of the mounted spring. Consequently, adjusting the operating force can be easily done by changing the spring.

[0019] Yet another major advantage of an operating mechanism according to the invention is that a visually attractive roller blind or Roman blind is obtained because the drive side and the idler side can be symmetrically executed and that the blind remains perfectly symmetrical and in the middle of the window.

[0020] In a preferred embodiment the first attachment element is also provided with a first brake surface that makes contact with a corresponding first contact surface provided to this end on the drive wheel such that both the drive side and the idler side are braked.

[0021] The first brake surface and first contact surface, on the one hand, and the second brake surface and second contact surface, on the other hand also act as axial bearing and ensure the rotation of the tube in the attachment elements.

[0022] For the same reason according to a preferred aspect of the invention, the first attachment element and the second attachment element are identical to each other, but are obviously mounted in a mirrored way.

[0023] According to a preferred characteristic of the invention, the drive side and the idler side are located at opposite axial ends of the tube.

[0024] With the intention of better showing the characteristics of the invention a few embodiments of an operating mechanism for a roller blind or Roman blind according to the invention are described hereinafter, by way of an example without any limiting nature, with reference to the accompanying drawings, wherein: figure 1 schematically shows an operating mechanism for a roller blind or Roman blind according to the invention; figure 2 shows a disassembled view similar to that of figure 1, but in a perspective view; figure 3 shows a cross-section according to line III-III of figure 1; figure 4 shows a cross-section according to line IV-IV of figure 2; figure 5 shows a cross-section according to line V-V of figure 2; figure 6 shows a cross-section according to line VI-VI of figure 1; figure 7 shows a cross-section of a variant of an operating mechanism according to the invention; figure 8 shows a detail of the clamping mechanism indicated with the arrow F8 in figure 7.

[0025] The operating mechanism 1 for a blind 2 shown in figure 1 comprises a tube 3, on which the blind 2 can be rolled up or unrolled, said tube 3 being rotatably suspended between a first attachment element 4 and a second attachment element 5. For the sake of simplicity the blind 2 is omitted in figures 1 to 3, but is added in figures 6 and 7.

[0026] The attachment elements 4,5 in this example are executed identically, such that the complete operating mechanism 1 also looks symmetrical. Obviously the attachment elements 4,5 are mounted in a mirrored way.

[0027] The disassembled condition, as shown in figure 2, shows that at a drive side 6, the tube 3 is provided with a drive mechanism 7 and at an idler side 8 is provided with a clamping mechanism 9.

[0028] The drive mechanism 7 comprises a first torque transmitting carriage 10, which in mounted condition, is at least partly applied in an open end 11 on the side of the drive side 6 of the tube 3, and a drive wheel 12 which is connected to the first carriage 10 in a torque transmitting manner.

[0029] In this example, the drive wheel 12 is provided with a groove 13 in which a cord 14 is applied to be able to drive the drive wheel 12. The cord 14 and drive wheel 12 can act as a pulley in this way.

[0030] The drive wheel 12, on the side facing the first attachment element 4, is provided with a first contact surface 15. The first attachment element 4, on the side facing the drive wheel 12, is in turn provided with a first brake surface 16.

[0031] In this example, the first carriage 10 is provided with axial grooves 17 along the outer contour, which correspond with protrusions 18 provided to this end on an inner wall of the tube 3. The grooves 17 and protrusions 18 can cooperate with each other in mounted condition such that a rotation of the drive wheel 12 and the first carriage 10 also causes a rotation of the tube 3.

[0032] It is understood that the protrusions 18 and corresponding grooves 17 could also be one or more corresponding cams and recesses or the like.

[0033] In this case, the idler side 8 with the clamping mechanism 9 is located opposite the drive side 6 of the tube 3 as shown in figure 3.

[0034] Said clamping mechanism 9 comprises a second torque transmitting carriage 19 which, in mounted condition, is partly applied in an open end 11 of the idler side 8 of the tube 3. In this example, the second carriage 19 is also provided with axial grooves 17, which correspond with the protrusions 18 on the inner wall of the tube 3.

[0035] The clamping mechanism 9 further comprises an idler wheel 20 which is connected to the second carriage 19 in a torque transmitting manner. Said idler wheel 20 is provided with a second contact surface 21, which faces the second attachment element 5. Said second attachment element 5 is in turn provided with a second brake surface 22 which faces the second contact surface 21 of the idler wheel 20.

[0036] Furthermore, the clamping mechanism 9 comprises a spring 23 which, in mounted condition, is tensioned between the second carriage 19 and the idler wheel 20.

[0037] The attachment elements 4,5 also comprise a cover 4A and 5A, which cover the threaded holes.

[0038] How the components interact with each other after assembly is shown better in the cross-sections of figures 3, 4 and 5.

[0039] More specifically, these figures show that the first carriage 10 and the drive wheel 12 are mounted on a shared first shaft 24, such that a rotation of the drive wheel 12 also causes a rotation of the first shaft 24 and the first carriage 10. Said first shaft 24 is also provided with a flat washer 25 that connects up against the first carriage 10.

[0040] Said first shaft 24 is bearing-mounted by means of a first bearing 26 in the first attachment element.

[0041] The second carriage 19 and the idler wheel 20 are in turn mounted on a second shaft 27, such that a rotation of the tube 3 and thus also the second carriage 19 also causes a rotation of the idler wheel 20.

[0042] The second shaft 27 is in turn bearing-mounted by means of a second bearing 28 in the second attachment element 4.

[0043] The first bearing 26 and second bearing 28 are radial bearings, for example needle bearings.

[0044] In this example, said first shaft 24 and second shaft 27 are bolts, but can also be custom-made components.

[0045] Figure 3 shows the operation of the operating mechanism 1 better, which, moreover, is very simple.

[0046] More specifically, in this example the second carriage 19 is provided with a central axial bore 29 in which the aforementioned spring 23 is partly housed. Consequently, the diameter of the bore 29 is slightly greater than the diameter of the used spring 23.

[0047] The spring 23 is applied around the second shaft 27. The axes of the spring 23, the bore 29 in the second carriage 19 and the second shaft 27 lie in each other's extension in this example.

[0048] Because the spring 23 has a greater diameter than the second shaft 27, around which the spring 23 is applied, the spring 23 can shift over the second shaft 27 in the axial direction, but also the second shaft 27 can shift in the central bore 29 of the second carriage 19.

[0049] Consequently, the spring 23 is able to axially push the idler wheel 20 against the second attachment element 5, such that the second brake surface 22 and the second contact surface 21 are pushed against each other and act as a brake.

[0050] Furthermore, the reaction force of the pressure between idler wheel 20 and second attachment element 5 ensures that the tube 3 is pushed in the direction of the first attachment element 4, such that the drive wheel 12 is also axially pushed against the first attachment element 4.

[0051] The first contact surface 15 is therefore also pushed against the first brake surface 16.

[0052] The friction between the respective contact surfaces 15,21 and brake surfaces 16,22 acts as a brake such that the tube 3 cannot rotate if no external force acts on the drive wheel 12.

[0053] In this example the idler wheel 20 is executed in two parts, i.e. an inner part 30 and an outer part 31 which are connected to each other in a torque transmitting manner. This is shown in more detail in the cross-section as shown in figure 5.

[0054] This means that a rotation of the outer part 31 also causes a rotation of the inner part 30. The inner part 30 is then provided with the second contact surface 21, which faces the second brake surface 22 of the second attachment element 5.

[0055] The outer part 31 is provided with a central bore 32, the diameter of which is greater than the diameter of the spring 23, such that the spring 23, in mounted condition of the operating mechanism 1, is tensioned between the second carriage 19 and the inner part 30. Indeed, it is the inner part 30 that is provided with the second contact surface 21 and that therefore must be pushed against the second brake surface 22.

[0056] To transfer the torque and the rotation from the outer part 31 to the inner part 30, the outer part 31 is provided with a cavity 33 in which the inner part 30 can at least partly be housed. In this example the contours of said cavity 33 correspond with the outer contour of the inner part 30, all this such that the inner part 30, in mounted condition, is fittingly enclosed in the outer part 31.

[0057] In this case, said aforementioned cavity 33 of the outer part 31 and the corresponding outer contour of the inner part 30 are polygonal but alternatively can also be provided with one or more corresponding cams and recesses such that the inner part 30 and outer part 31 are connected to each other in a torque transmitting manner.

[0058] Because the spring 23 only pushes against the inner part 30 and not against the outer part 31, the outer part 31, which remains visible in mounted condition, always remains in the same position relative to the rest of the operating mechanism 1. Consequently, the outer part 31 will only rotate but not be moved axially. This has the advantage that the operating mechanism 1 remains completely symmetric, also during the operation of the operating mechanism 1.

[0059] Apart from rotate, the inner part 30, on the other hand, can also be moved axially such that the second contact surface 21 can be pushed against the second brake surface 22 under the influence of the spring 23.

[0060] The axial movement of the inner part 30 is partly made possible thanks to the play between the inner part 30 and outer part 31, and also thanks to the play between a head 34 of the second shaft 27 and the second carriage 19.

[0061] Furthermore, said play ensures that the tube 3 is easy to mount between the already mounted first attachment element 4 and second attachment element 5. Indeed, the tube 3 can first be attached to the first attachment element 4, after which the idler wheel 20 can be pushed in against the spring force and subsequently the tube 3 can be mounted in the second attachment element 5. After releasing the idler wheel 20, the spring 23 will push the second shaft 27 in the direction of the second attachment element 5 such that the second shaft 27 is coupled with the second attachment element 5.

[0062] The drive of the operating mechanism 1 is easier to understand based on the cross-section as shown in figure 6, whereby a blind 2 is applied on the tube 3.

[0063] At rest, this means, when no external forces engage on the drive wheel 12, the axial force with which the spring 23 pushes the brake surfaces 16,22 and contact surfaces 15,21 against each other is greater than the tangential force A as a result of the weight of the amount of unrolled blind mass. Said tangential force A is indicated in figure 6 with arrow A.

[0064] As the brake force, under the influence of the spring 23, between the contact surfaces 15,21 and brake surfaces 16,22 is greater than the tangential force A, the tube 3 and thus also the blind 2 will not rotate, such that the blind 2 remains suspended at the same height.

[0065] However, when an operating force B is exerted on the cord 14, said operating force B of the cord 14 will be transmitted to the drive wheel 12, whereby the drive wheel 12 is subjected to a rotation which is transmitted to the tube 3.

[0066] The blind 2 opens or rolls up when the operating force B in the figure is exerted to the left of the cord 14 and is greater than the tangential force A.

[0067] The blind 2 closes or unrolls when the operating force B in the figure is exerted to the right of the cord 14 and is greater than the tangential force A.

[0068] When no operating force B is exerted on the cord 14, the blind 2 will remain suspended. Consequently, the blind 2 can be put at any height in a continuous way.

[0069] The first bearing 26 and second bearing 28 guarantee that the total weight C, which is the sum of the operating mechanism 1, the blind 2 and the operating force B, can be rotated when the operating force B is exerted to the left or right of the cord 14.

[0070] Adjusting the required operating force B to operate the operating mechanism 1 can be varied by replacing the applied spring 23 by a spring 23 with a different spring constant or by changing the compression of the spring 23.

[0071] Alternatively, the compression of the spring 23 can also be changed by applying shims in the bore 29 of the second carriage 19.

[0072] The variant shown in figure 7 is identical to the operating mechanism 1 shown in figures 1 to 6, but differs in the idler wheel 20 and the second shaft 27.

[0073] Indeed, figure 7 shows that the idler wheel 20 is made in one piece and there is thus no inner part 30 and outer part 31.

[0074] The operation is analogue to the variant described above, the difference being that the complete idler wheel 20 is moved axially under the influence of the spring 23. However, this has the disadvantage that the play between the drive wheel 12 and the first attachment element 4 and the play between the idler wheel 20 and the second attachment element 5 are not always equal in size, such that the operating mechanism 1 does not always look perfectly symmetric.

[0075] The exploded view of the clamping mechanism 9 in figure 8 shows that the second shaft 27 is also different from the variant described above. The second shaft 27 is an oblong body with two different cross-sections. A first part 35 has a circular cross-section while a second part 36 has a polygonal cross-section. Alternatively, the second part 36 could also have a substantially circular cross-section with a local cam or the like.

[0076] The spring 23 is applied around the first part 35 of the second shaft 27 with circular cross-section and is tensioned in the bore 29 of the second carriage 19, between the second carriage 19 and the second part 36 with polygonal cross-section of the second shaft 27.

[0077] The first part 35 of the second shaft 27 runs completely through the second carriage 19 and at its end is provided with a circlip 37 which limits the axial movement of the second shaft 27 relative to the second carriage 19.

[0078] The opposite end of the second shaft 27, at the free end of the second part 36, is fittingly enclosed during the assembly in a cavity 38 of the idler wheel, with similar contours as the cross-section of the second part 36, such that the second shaft 27 and the idler wheel 20 are connected to each other in a torque transmitting manner.

[0079] In this variant, not the second shaft 27, but the idler wheel 20 is bearing-mounted in the second attachment element 5. It is understood that in this case the idler wheel 20 is provided with the second contact surface 21 which under the influence of the spring 23 is pushed against the second brake surface 22.

[0080] The further operation is completely analogue to the variant described above and here also the spring 23 will push the brake surfaces 16,22 and the contact surfaces 15,21 against each other such that the tube 3 cannot rotate when no external forces engage on the drive wheel 12.

[0081] Although the shown embodiments relate to a roller blind, for the person skilled in the art it is clear that the operating mechanism 1 can also be applied to Roman blinds or pleated blinds. In that case the blind 2 is provided with at least two ropes that are wound or unwound on the tube 3. Said ropes are located at a distance of sixty centimetres from each other for example.

[0082] Although not shown in the figures the cord 14 or the like can be provided with an extra weight to keep the cord 14 taut or to influence the operating force B of the operating mechanism 1.

[0083] Although in the described embodiments the brake surfaces 16,22 are provided on the attachment elements 4,5 and the contact surfaces 15,21 on the drive wheel 12 and the idler wheel 20 respectively, it is also possible that the contact surfaces 15,21 are provided on the attachment elements 4,5 and the brake surfaces 16,22 on the drive wheel 12 and the idler wheel 20.

[0084] Although the shown embodiments, both on the idler side 8 and the drive side 6, are provided with brake surfaces 16,22 and contact surfaces 15,21 it is possible that only the idler side 8 is provided with a brake surface 22 and contact surface 21 and that the drive side 6 is not. However, in that case an axial bearing must be provided on the drive side 6 to accommodate the spring force of the spring 23. Such axial bearing is for example a thrust bearing.

[0085] For the person skilled in the art it is clear that the groove 13 in the drive wheel 12 can be absent if a drive wheel with teeth or a sprocket is used, whereby in such case the cord 14 can be replaced by a chain or ball chain.

[0086] It is understood that many feasible embodiments are possible and more specifically relating to the clamping mechanism 9.

[0087] The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but an operating mechanism according to the invention can be realised in all kinds of forms and dimensions, without departing from the scope of the invention.

Claims

1. Operating mechanism for a roller blind or Roman blind, comprising a tube (3) on which the blind (2) can be rolled up and unrolled, whereby a drive side of (6) of the tube (3) is provided with a drive mechanism (7) and an idler side (8) of the tube (3) is provided with a clamping mechanism (9), characterised in that the drive mechanism (7) comprises a first torque transmitting carriage (10) to be applied at least partly in an open end (11) of the drive side (6) of the tube (3) and a drive wheel (12) that is connected to the first carriage (10) in a torque transmitting manner, whereby the drive wheel (12) is provided with a cord (14) or the like to be able to drive the drive wheel (12), whereby the drive mechanism (7) is further provided with a first attachment element (4) for attaching the operating mechanism (1) on the level of a window or the like, whereby the clamping mechanism comprises (9) a second torque transmitting carriage (19) to be applied at least partly in an open end (11) of the idler side (8) of the tube (3), an idler wheel (20) that is connected to the second carriage (19) in a torque transmitting manner, whereby the clamping mechanism (9) is further provided with a second attachment element (5) for attaching the operating mechanism (1) on the level of the window or the like, said second attachment element (5) being provided with a second brake surface (22) that makes contact with a corresponding second contact surface (21) provided to this end on the idler wheel (20), whereby the clamping mechanism (9) is further provided with a tensioned spring (23) which is applied between the second carriage (19) and the idler wheel (20) and which pushes the idler wheel (20) in an axial direction away from the second carriage (19), all this such that after assembly the spring (23) pushes the brake surfaces (16,22) and contact surfaces against each other (15,21) in an axial direction.

2. Operating mechanism according to claim 1, characterised in that the first attachment element (4) is provided with a first brake surface (16) that makes contact with a corresponding first contact surface (15) provided to this end on the drive wheel (12).

3. Operating mechanism according to any one of the previous claims, characterised in that the drive side (6) and the idler side (8) are positioned at opposite axial ends of the tube (3).

4. Operating mechanism according to any one of the previous claims, characterised in that the drive wheel (12) along the outer contour is provided with a groove (13) in which the aforementioned cord (14) or the like is applied, all this such that the drive wheel (12) and cord (14) act as a pulley.

5. Operating mechanism according to any one of the previous claims, characterised in that the drive mechanism (7) is provided with a first bearing (26) and the clamping mechanism (9) is provided with a second bearing (28), to bearing-mount the tube (3) in the first attachment element (4) and second attachment element (5).

6. Operating mechanism according to any one of the previous claims, characterised in that the drive mechanism (7) is further provided with a first shaft (24), on which the first bearing (26), the drive wheel (12) and the first carriage (10) are mounted, all this such that a rotation of the drive wheel (12) also causes a rotation of the first shaft (24) and the first carriage (10).

7. Operating mechanism according to any one of the previous claims, characterised in that the clamping mechanism (9) is further provided with a second shaft (27), on which the second bearing (28), the idler wheel (20) and the second carriage (19) are mounted, all this such that a rotation of the second carriage (19) also causes a rotation of the second shaft (27) and the idler wheel (20).

8. Operating mechanism according to claim 7, characterised in that the second carriage (19) is provided with an axial bore (29) in which the aforementioned spring (23), in mounted condition of the operating mechanism (1), is partly housed, whereby the spring (23) is applied around the second shaft (27), all this such that the second shaft (27) is axially slideable in the bore (29), such that the spring (23) pushes the second carriage (19) and the idler wheel (20) apart.

9. Operating mechanism according to any one of the previous claims, characterised in that the idler wheel (20) is executed in two parts, i.e. an outer part (31) and an inner part (30) which are connected to each other in a torque transmitting manner, all this such that a rotation of the outer part (31) also causes a rotation of the inner part (30) and whereby the inner part (30) is provided with the aforementioned second contact surface (21).

10. Operating mechanism according to claim 9, characterised in that the outer part (31) is provided with a central bore (32), the diameter of which is greater than the diameter of the spring (23), such that the spring (23), in mounted condition of the operating mechanism (1), is tensioned between the second carriage (19) and the inner part (30).

11. Operating mechanism according to claim 9 or 10, characterised in that the outer part (31) is provided with a cavity (33) which corresponds with the outer contour of the inner part (30), all this such that the inner part (30), in mounted condition of the operating mechanism (1), is fittingly enclosed in the outer part (31).

12. Operating mechanism according to claim 11, characterised in that the aforementioned cavity (33) and the corresponding outer contour are polygonal or that the inner part (30) and outer part (31) are provided with one or more corresponding cams and recesses such that the inner part (30) and outer part (31) are connected to each other in a torque transmitting manner.

13. Operating mechanism according to any one of the previous claims, characterised in that the first attachment element (4) and the second attachment element (5) are identical to each other.

14. Operating mechanism according to any one of the previous claims, characterised in that carriages (10,19) are provided with axial grooves (17) along the outer contour which correspond with protrusions (18) provided to this end at an inner wall of the tube (3), all this such that a rotation of the carriages (10,19) causes a rotation of the tube (3) and vice versa.

15. Operating mechanism according to any one of the previous claims, characterised in that the operating force (B) of the operating mechanism (1) can be adjusted by varying the force that the spring (23) exerts when pushing apart the second carriage (19) and the idler wheel (20), for example by reducing the depth of the bore (29) in the second carriage (19) and / or partially filling it with one or more shims.

16. Operating mechanism according to any one of the previous claims, characterised in that in the case of a Roman blind, the Roman blind is provided with at least two ropes that are rolled up around the tube (3) when opening the Roman blind and unrolled from the tube (3) when closing the Roman blind.

17. Operating mechanism according to any one of the previous claims, characterised in that the cord (14) or the like is provided with a weight, to keep the cord (14) taut and / or to influence the operating force (B) of the operating mechanism (1).

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