GB2431190A

GB2431190A - Adjustable screen

Info

Publication number: GB2431190A
Application number: GB0520816A
Authority: GB
Inventors: John Benjamin Slater
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-10-13
Filing date: 2005-10-13
Publication date: 2007-04-18
Anticipated expiration: 2025-10-13
Also published as: GB2431190B; GB0520816D0

Abstract

A screening device has a screening material 1 between and wound around rollers 2, 3. Each roller is independently movable, each moving with a combined translational and rotational movement so that with movement of one roller towards or from the other roller it rotates to winds or unwinds the screening material. The screening device also has tensioning means to keep taut the screening material 1 between the rollers as they are moved, a mechanism being provided to allow the rollers independently to be located in a plurality of positions.

Description

Title: Adjustable screen

Field of the Invention:

The invention relates to a screen that operates using two rollers to make it adjustable in both size and position by having opposite edges independently repositionable.

Prior Art:

Most Prior Art screens that operate from one roller are limited by the fact that they fix the roller, making only one edge of the screen adjustable. A few Prior Art devices allow the roller to be repositioned vertically on rails, cords or movable brackets.

Most Prior Art screening or shading devices that have opposite edges separately movable do so by using screening material that can itself compact or expand, for example in the manner of a pleated or cellular blind.

Several Prior Art screening devices use a screen between two rollers but one or both rollers is in a fixed position.

The only published device using two movable rollers known to the applicant at this time is UK Patent Application GB 2108557 (Brian Hingpo Tse). This uses a screen between two horizontal rollers which are supported vertically by an arrangement of two cords which permits each roller to be grasped and moved up or down by hand. Any slack produced in the screen is then taken up by rotating the bottom roller by hand.

Summary of the invention:

The invention is hereinafter described using the following tenns: line - a member whose length is substantially greater than its breadth and width which features longitudinal strength, lateral flexibility and relatively low longitudinal elasticity, such as but not limited to cord, string, wire, rope, chain, beaded string, cable, twine, belt, band, or functionally similar members or members constructed from any combinations of these screen - a member whose thickness is substantially less than its length and width which features lateral flexibility (such that it could be wound around a roller) such as but not limited to fabric, cloth, netting, sheet material such as plastics or metals or other kinds of woven, fabricated or natural sheet matenal or composite which may have holes, folds, gaps, surface variations, reflective or other coatings, reinforcement elements, designs, patterns or text or other substructural elements roller - a tube or rod or other substantially cylindrical member to which an edge of a screen may be attached, and around which the screen may be wound driving-wheel - a wheel functionally suited to converting linear movement into rotational movement such as but not limited to a pulley where linear movement relative to a line causes the pulley to rotate, or a gear where linear movement relative to a chain or rack causes rotation of the gear direction-changer - a device of known design for converting the tension in a line in one direction into tension in the same or another line in another direction, as exemplified by but not limited to lines passing over rotating or smooth surfaces such as pulleys, wheels, gears, smooth rods, loops or other members; or mechanical devices such as but not limited to levers, electromechanical devices, magnetic devices or any other device which achieves the necessary change in tension direction torque-device - a component which operates between two members that share a substantially common axis of rotation in such a way as to produce and maintain a torque between the two members with respect to their shared axis, as exemplified by but not limited to all manner of springs; stretched or twisted components made of matenals with suitable elasticity; components of known design that produce a torque by pneumatic, magnetic, electrical or electromagnetic means; and all manner of machines or mechanical devices of known design that can produce and maintain a torque between two such members In addition, all descriptions, drawings and claims hereinafter use conventional three-dimensional Cartesian axes X, Y and Z to specify the relative positions, orientations and movements of the components. Various embodiments of the invention can be made to operate with these axes inclined at various angles to the horizontal.

This invention relates to a flexible screen whose effective area operates between two substantially parallel movable rollers. The rollers can be independently repositioned and this has the effect of extending, retracting or moving the effective area of the screen. Each movable roller is substantially parallel to the X axis and rotates about an axis of rotation through its centre and substantially parallel to the X axis. The rollers move independently in a direction substantially parallel to the Y axis and have substantially equal X coordinates. One edge of the screen is attached to one roller and the opposite edge of the screen is attached to the other roller in such a way that the axes of rotation of the two rollers are both substantially parallel to the plane of the effective area of the screen when it is tensioned between them. At various times during the use of the invention either or both of the two rollers may have part of the screen wound around them by the rotation of the roller about its axis.

The invention depends upon a driving mechanism which must ensure that when either roller is moved in a direction substantially parallel to the Y axis to extend the screened area, the said roller simultaneously rotates about its axis to unwind a length of screen which is close to being equal to the distance moved by the roller. Conversely, when either roller moves to reduce the screened area, it simultaneously rotates about its axis to wind up a length of screen which is close to being equal to the distance moved by the roller.

Depending on the manner in which the movement is produced, each roller may also incorporate a separate braking mechanism to allow the roller to be parked in a plurality of positions. In other embodiments the driving mechanism may itself act as a brake.

This combined rotational and translational movement of each roller may be produced by one or more driving-wheels on each roller. The embodiment described hereinafter uses two driving-wheels per roller, but embodiments may have any number of driving-wheels per roller. These driving-wheels are concentric with the roller and share the roller's axis of rotation which is substantially parallel to the X axis.

Alternatively the dnving-wheels may be a functionally equivalent integral part of the roller.

The required rotational and translational motion may be created by arranging the driving-wheels so that they roll along a member and have a radius which is substantially equal to that of the roller. A few example embodiments will serve to explain this and to illustrate the variety of ways in which it can be implemented: the driving-wheels may be toothed wheels or gears or pinions which engage with and roll along toothed racks or engage with and run along chains; they may be flanged wheels that run along rails, or wheels that run along and grip a surface by having a high coefficient of friction in the manner of a tyre on a road; they may be pulleys that run without slipping along lines, or hang in a loop of line one end of which is fixed, and run up and down the line as the other end is moved up and down, pulled and released, or wound and unwound, possibly via one or more direction-changers; in a similar way, they could be toothed wheels or gears hanging in a loop of chain which would operate in the same way.

To keep the effective region of the screen between the two rollers tensioned, a tensioning-means is incorporated. The tensioning-means in some embodiments is a torque-device fitted to one or both rollers.

The torque-device operates between one or more of the driving-wheels and its roller to produce and maintain a torque between them throughout normal operation. The tensioning-means is necessary because as the screen is progressively wound around a roller the effective radius of the roller increases because of the thickness of the screen. With many of the driving-wheel embodiments this makes it impossible to ensure that the length of screen unwound or wound up by the rotation is exactly equal to the distance moved by the translational movement of the roller throughout the full range of its movement. The tensioning-means compensates for this discrepancy by taking up or releasing any slack in the screen which would otherwise become present. The tensioning-means also compensates for any possible stretching or shrinkage of the screen during its lifetime. An alternative to the torque-device would be to use screen matenal with suitable longitudinal elasticity.

Alternatively the required rotational and translational motion may be created by the operation of a suitable machine of known design attached to one or both rollers such as but not limited to electric motors or servos. Alternatively the rotational component of the required motion may be produced predominantly or exclusively by a torque-device in one or both rollers which serves to roll up the screen as the rollers are moved towards each other.

Embodiments vary in the orientation of the axes and in the details of the driving mechanism and tensioning-means. A preferred embodiment will now be described by way of example only.

Brief description of the drawings:

The invention will now be described solely by way of example and with reference to the accompanying

drawings which form part of this specification:

FIGURE us an elevation looking in a direction parallel to the Z axis showing the rollers and screen with the screen fully unrolled and their alignment and attachment in the preferred embodiment as well as the dimensions L, D and R referred to in the text FIGURE 2 is an elevation of the preferred embodiment looking in a direction parallel to the Z axis showing a suspension and driving mechanism for both ends of the roller which has the smaller Y coordinate FIGURE 3 is an elevation of the preferred embodiment looking in a direction parallel to the Z axis showing a suspension and driving mechanism for both ends of the roller which has the greater Y coordinate FIGURE 4 is a section view along the line IV-IV of Figure 2 showing a suspension and driving mechanism for one end of the roller which has the smaller Y coordinate FIGURE 5 is a section view along the line V-V of Figure 3 showing a suspension and driving mechanism for one end of the roller which has the greater Y coordinate FIGURE 6 is a cross section of the preferred embodiment parallel to the XY plane through the centre of the roller which has the smaller Y coordinate showing the torque-device FIGURE 7 shows four diagrammatic cross-sections parallel to the YZ plane showing four possible arrangements of the screen wound around the rollers

Description of the preferred embodiment

The preferred embodiment aligns the Y axis substantially vertical, uses lines and pulleys as the driving mechanism, is supported by being suspended by the lines from a supporting structure, uses a coiled spring to produce the torque-device, and can be manually operated by pulling or releasing the lines.

The arrangement shown in figure 1 shows the two cylindrical rollers 2 and 3 of substantially equal length R and diameter D and a rectangular screen 1 whose width is substantially equal to R and whose length L is not related to the value of R. As shown in figures 2 and 3, roller 2 has a Y coordinate greater than or equal to the Y coordinate of roller 3 throughout normal use of this embodiment. The rollers 2 and 3 are likely to have Z coordinates which do not differ significantly as shown in figures 4 and 5, though any difference between their relative Z coordinates has no impact on the functionality of the embodiment and is therefore unspecified. The effective region of the screen 1 between the two rollers 2 and 3 is likely to be substantially parallel to the XY plane provided that the said difference between the Z coordinates of the two rollers is small compared to the difference between their Y coordinates, a situation which is likely in the normal use of this embodiment.

Each roller 2 and 3 has a driving-wheel at each end by which it hangs from two loops of line. The line and driving-wheels in this embodiment are a beaded string pulley system of known design in which the line comprises cord with equidistantly spaced beads along its length and the driving-wheels are pulleys shaped to engage with the beads so that the line turns the driving-wheel without slipping. A constraining member (guard) of known design can be used to keep the line engaged with the driving-wheel. The radius of the surface of the pulley which is in contact with the line should be substantially equal to a radius determined by winding the screen around the roller to which the pulley is attached until approximately half the length of the screen has been wound up and then measuring the outer radius of the rolled-up portion of the screen around the roller.

Roller 2 has two such pulleys 10 and 11 attached to its ends as its driving-wheels as shown in figure 2.

Roller 3 is also fitted with two pulleys 12 and 13 as shown in figure 3 but these are attached using a torque- device as shown in figure 6 and constructed as follows. The two driving- wheels 12 and 13 are fixed to a solid axle 24 which runs through the centre of the roller 3 such that the axle, the roller and the dnving- wheels are concentric and have the same axis of rotation. The roller 3 is hollow to accommodate the axle 24 and is connected to the axle 24 by bearings 26 and 27 which can be any connecting mechanism of known design which allows the roller 3 and axle 24 to rotate relative to each other around their common axis while substantially allowing no other direction of relative movement or rotation. Minimising the friction in these bearings 26 and 27 gives optimal operation of the embodiment, though a certain amount of friction can be present without any impact on the successful operation of the embodiment. A helical coiled spring 25 with internal radius greater than that of the axle 24 and external radius less than the inner radius of the hollow roller 3 is positioned around the axle 24 inside the roller 3 between the bearings 26 and 27.

One end of the spring 25 is firmly attached to the outer surface of the axle 24 and the other end is firmly attached to the inside surface of the hollow roller 3.

This embodiment is supported by hanging from a supporting member such as but not limited to a beam, the ceiling, the lower face of the member across the top of an architectural aperture, or brackets attached to a wall. Roller 2 is suspended from the supporting structure by two lines 7 and 17 as shown in figures 3 and 5.

One end of line 7 is attached to the supporting member by a bracket 8. From here line 7 passes around and under the pulley 10 and then through direction-changers 9 and 21 leaving its unattached end hanging from direction-changer 21. The direction-changers in this embodiment are small pulleys whose mounting is attached to the supporting member. Similarly line 17 is attached to the supporting structure by bracket 18, passes around and under the pulley 11 and then through direction-changers 19 and 23 leaving its unattached end hanging from direction-changer 23. To achieve a full range of movement the length of line 7 should comfortably exceed (2L + R + 3.6D) (using the lengths L, D and R as shown on figure 1) and the length of line 17 should comfortably exceed (2L + 3.6D). The unattached ends of lines 7 and 17 are attached to each other with the lines 7 and 17 taut and roller 2 substantially horizontal by tying a knot 28. With this mechanism, if the knot 28 is pulled progressively (for example by a human operator) the roller 2 will move upwards with the required simultaneous rotational and translational movement and if the knot 28 is released progressively (for example by a human operator), the roller 2 will move downwards under gravity with the same simultaneous rotational and translational movement. The lines in this embodiment are pulled and released by hand and parked by attaching to a fixed bracket; alternative embodiments may use parking mechanisms of known design which work by gripping or pinching the line or by restricting the motion of one or more of the direction changers. Alternative embodiments can move and park the roller by winding the lines using a winch turned by a handle or motor-driven mechanism of known design which may have sufficient friction in its stationary position to park the roller at a plurality of positions or may incorporate a suitable braking mechanism.

In the same way roller 3 is independently suspended from the supporting structure by two further lines 4 and 14 as shown in figures 2 and 4. One end of line 4 is attached to the supporting member by a bracket 5.

From here line 4 passes around and under the pulley 12 and then through direction-changers 6 and 20 leaving its unattached end hanging from direction-changer 20. Similarly line 14 is attached to the supporting structure by bracket 15, passes around and under driving-wheel 13 and then through direction- changers 16 and 22 leaving its unattached end hanging from direction- changer 22. To achieve a full range of movement the length of line 4 should comfortably exceed (2L + R + 3.6D) and the length of line 14 should comfortably exceed (2L + 3.6D). Before the unattached ends of lines 4 and 14 are attached to each other by tying a knot 29, not only must the lines 4 and 14 be taut and roller 3 be substantially horizontal, but also the driving-wheels 12 and 13 should be turned relative to roller 3 in such a direction as will produce a torque which will tension the screen between the two rollers. This needs to be done without the pulley guards in place. With this mechanism, if the knot 29 is pulled progressively the roller 3 will move upwards with the required simultaneous rotational and translational movement and if the knot 29 is released progressively, the roller 3 should move downwards under gravity with the required simultaneous rotational and translational movement. As with roller 2, the lines in this embodiment are pulled and released by hand and parked by attaching to a bracket, but other embodiments could use mechanisms as described above for roller 3. This roller needs to be set up with sufficient torque to keep the screen taut throughout the full range of movement, but the torque must not be so great as to prevent the roller 3 from descending under its own weight when the lines 4 and 14 are released.

This embodiment uses the arrangement of lines in figures 4 and 5 which implement the pattern shown in figure 7a. The pattern shown in figure 7b can be implemented using a mirror-image of figures 4 and 5. If preferred, an alternative embodiment can be constructed to implement pattern 7c or 7d simply by reversing the direction of the line around its driving-wheel at each end of one of the two rollers and adjusting the positions of the brackets and direction changers accordingly.

This embodiment aligns the Y axis substantially vertical because the two rollers 2 and 3 hang under the influence of the force of gravity. Similar embodiments with the Y axis at an angle to the vertical can be constructed by arranging for the mechanism to operate in the presence of one or more additional forces which have a non-zero component in a direction parallel to the Z axis. Such forces may be applied to the device by means such as but not limited to: a mechanical constraint such as grooves, supports, struts, lines, brackets, an inclined plane or other such fixed members; by springs or other elastic elements; using forces such as magnetic, electrical, electromagnetic, moving fluid or centripetal force.

Claims

Claims: The embodiments of the invention in which an exclusive property or

pnvilege is claimed are defined as follows: 1. A screening device whose position and size can be adjusted comprising a flexible screen between and separately wound around two substantially parallel independently movable rotatable rollers whose movement is controlled such that as either roller is moved in a direction to increase the effective area of the screen it also rotates in such a way as to unwind the screen progressively and such that as either roller is moved in a direction to decrease the effective area of the screen it also rotates in such a way as to wind up the screen progressively and incorporating a tensioning-means to keep the screen between the rollers substantially taut by compensating for any discrepancy between the distance of translational movement of the rollers and the length of screen wound up or unwound and incorporating a mechanism which allows the two rollers to be independently parked in a plurality of positions
2. A screening device according to claim 1 in which the required translational and rotational movement of each roller is produced by one or more driving-wheels which turn as they are moved away from or towards each other
3. A screening device according to claim 2 in which the driving-wheels are toothed wheels or gears or pinions which engage with and run along toothed racks to create the required rotational and translational motion
4. A screening device according to claim 2 in which the driving-wheels are toothed wheels or gears which engage with and run along chains to create the required rotational and translational motion
5. A screening device according to claim 2 in which the driving-wheels are pulleys and run without slipping along lines to create the required rotational and translational motion
6. A screening device according to claim 2 in which the driving-wheels run along a surface or track such that said surface or track and the outer circumference of said driving-wheel have a high enough mutual coefficient of fnction to create the required rotational and translational motion without slipping
7. A screening device according to claim 1 in which the rollers are fitted with a motor or other suitable machine of known design to create the required rotational and translational motion
8. A screening device according to claim I in which the rollers turn against a torque-device such that the tension in said torque-device winds the screen onto a roller as either of the two rollers is moved towards the other roller
9. A screening device according to claim 3 4 5 6 7 or 8 in which the tensioning-means is achieved by using screen material which has a suitable degree of elasticity in the direction from one roller to the other
10. A screening device according to claim 3 4 5 or 6 in which the tensioning-means is achieved by one or more torque-devices each of which operates between a roller and one or more of its driving wheels
11. A screening device according to claims 9 and 10 in which the tensioning-means is achieved by a combination of the features thereof
12. A screening device according to claim 4 or 5 in which each of the driving-wheels hangs freely under gravity in a loop of line which controls its translational and rotational movement and which incorporates a tensioning-means according to any one of claims 9 10 or 11
13. A screening device according to claim 12 in which one end of each line is fixed to a supporting structure above the device and the other end is pulled or released possibly via one or more direction-changers such that all lines controlling the same roller are pulled and released together to control its translational and rotational movement
14. A screening device according to claim 13 in which the lines are pulled and released by a person and in which each roller is parked by attaching its controlling lines to a fixed bracket
15. A screening device according to claim 13 in which the lines are pulled and released by a person and in which each roller is parked by a device of known design which grips or pinches its controlling lines
16. A screening device according to claim 13 in which the lines are pulled and released by handle- operated winches of known design which incorporate either a braking mechanism or sufficient friction to park the rollers in a plurality of positions
17. A screening device according to claim 13 in which the lines are pulled and released by motordriven winches of known design which when stopped can either prevent movement or incorporate a braking mechanism to park the rollers in a plurality of positions
18. A screening device according to claims 12 13 14 15 16 or 17 in which insofar as the force of gravity plays a part in the operation of this device an alternative or additional force may be used to play an equivalent role enabling the device to operate in a position which is not necessarily vertical
19. A screening device according to claim 18 in which the additional force is provided by mechanical constraint such as grooves, supports, struts, lines, brackets, an inclined plane or other such fixed members
20. A screening device according to claim 18 in which the additional force is provided by springs or other elastic elements
21. A screening device according to claim 18 in which any other source or sources of additional force such as but not limited to magnetic, electrical, electromagnetic, moving fluid, centripetal force is used