Technical field

This invention relates to curtain driving means, that is to say, to driving means arranged, when suitably mounted in position, for drawing to and fro across an opening or space to be covered, curtains or other vertical sheet or strip materials (for example, as in vertical blinds) acting as curtains, which curtains are suspended from suspension devices carried on and movable along a suspension track or rail system secured over and across said opening or space.

A curtain suspension track or rail system may comprise a single, full-length track or rail extending over the full span of the curtains, or it jnay comprise, for example, two half-length tracks or rails, which together extend across that span and have at the centre of the span over-lapping portions. For simplicity's sake, in what follows the term 'curtain suspension track ' or more simply 'curtain track' will be used to cover, where appropriate, both kinds of track or rail system as referred to above.

The present invention relates more particularly to curtain driving means for use with curtains of the sizes commonly encountered in domestic households and commercial offices, though the application of the present invention is not limited in this respect.

Background art

It is known to provide, as such a driving means, a system of cords for drawing curtains by their respective leading edge portions to and fro across the opening; and to accommodate such cords in supporting channels provided in the curtain track system, so as to prevent them sagging in an unsightly manner across the said opening. It is also known to operate such a cord system manually, or by means of an electrically powered drive unit.

• _

-2-

One such drive unit comprised an electric driving motor provided with a cord driving pulley, which pulley drivingly engaged a tightly stretched continuous loop of curtain drawing cord which extended downwardly thereto from said curtain track cord channels. However, the bulkiness of that particular form of drive unit prevented it in most cases from being mounted closely adjacent the curtain track, there being an insufficient distance between the wall adjacent the track and the curtains suspended from that track. Hence, the use of such an electric drive unit required the motor to be mounted somewhat remotely from the track, and the consequent use of long lengths of curtain drawing cord gave rise to problems caused by the stretching of such long cord lengths. Moreover, that form of drive unit could be applied to an existing curtain installation only when the curtain track incorporated, or could incorporate, a suitable curtain driving cord system for drawing the curtains along the track.

In one alternative form of prior art electric curtain driving means, the electric drive unit was formed as an integral part of the curtain suspension track system, so that it had to be made to measure and could not be applied separately to an existing track system. Moreover, such an integral system had a relatively high selling price, so that the adoption of such an integral system involved the scrapping of any existing curtain track system, and a high outlay for the replacement integral system.

The present invention seeks to provide an alternative form of curtain driving means which does not have the disadvantages of the prior art mentioned above, and which in particular can be fitted to most existing curtain suspension track systems, both readily and at a relatively low cost; and which can be readily adapted to suit curtain suspension tracks of various spans.

Disclosure of the invention

According to the present invention, there is provided a curtain driving means for use in association with a curtain suspension system which comprises a track or rail system and a plurality of curtain suspension members carried thereon, which driving means comprises:-

(a) a drive unit arranged for mounting in a predetermined operating position at one side of an opening or space to be covered by a curtain or curtains when drawn to, said unit incorporating a rotatable belt-driving pulley, and said pulley bein aligned, when said drive unit is mounted in its said operating position, for rotation about a vertical axis;

(b) a return unit arranged for mounting in a predetermined operating position on the said wall at the opposite side of said opening or space, and incorporating a rotatable belt- return pulley, which pulley, when said return uxiit is mounted in its said operating position, is aligned for rotation about a vertical axis;

(c) a driving belt in the form of a continuous closed loop of a belt material having a thin, broad cross section, ■ which belt loop is arranged to be stretched tightly over and to engage at its respective end portions the said rotatable drive and return pulleys respectively (when mounted in their respective positions), the belt when in position on said pulleys having its greater transverse dimension extending in the vertical direction and being so tensioned as to prevent the belt sagging under its own weight to any substantial extent; and

(d) for each curtain to be drawn along said track or rail system a link member secured on said belt loop (when stretched over said pulleys) at an appropriate driving position, which link member is arranged for coupling with said curtain or a curtain suspension member supporting said curtain.

According to one important preferred feature of the present invention, said belt material comprises a substantially inextensible strip material in which are formed on one face thereof uniformly spaced teeth which extend transversely of the length of the strip material, and said belt driving

pulley comprises a toothed pulley arranged to be engaged by and to cooperate in a driving manner with the teeth of said belt material. Said belt return pulley may comprise as desired a similarly toothed pulley, or a plain cylindrical pulley.

Said loop of belt material may comprise at least two similar pieces of said toothed belt material joined in overlapping relationship at their respective end portions, one such piece having its teeth facing inwardly of the loop for engaging said toothed driving pulley, and the other piece having its teeth facing outwardly of the loop, and each pair of said overlapping end portions of the respective belt pieces being held together with their respective sets of teeth in inter-engagement.

Each said pair of said overlapping portions may be secured, with the respective sets of teeth of said portions inter- engaged, by a clamp. Such a clamp.pa comprise a U-shaped clip of a deformable sheet material, which clip has been compressed and plastically deformed on to a said pair of overlapping end portions. Alternatively, such a clip may be made of a resilient material, and be opened to place it in position, whereafter it returns to its closed position in which it then clasps the opposed overlapping end portions and secures them together.

According to another important feature of the present invention, said driving pulley is drivingly carried on the end of an elongate driving shaft which is supported from a base member, and which is drivingly coupled at its opposite end to a driving means, which driving means is carried on the said base member at a predetermined substantial distance * from the said driving pulj»ey such that that pulley may be positioned substantially at the height of the said curtain suspension members and between them and the adjacent wall, whilst said driving means is disposed between said wall and the adjacent curtain at a position substantially below the level of a row of curtain hooks on and by means of which

said curtain is suspended from said curtain suspension members. With such a drive unit, the drive to the curtains is applied directly to the curtain suspension members (or even to the curtain hooks carried thereby) , whilst the said driving means is capable of being concealed lower down behind the adjacent curtain.

The belt driving means advantageously comprises a high speed electric motor having its output shaft coupled to a high- ratio, speed-reduction gear unit, the output shaft of which constitutes said elongate drive shaft carrying said belt driving pulley; and said motor is preferably a low-voltage motor supplied via a step-down transformer from the normal domestic electricity supply circuit.

Other features of the present invention will appear from the description that follows hereafter, and from the claims appended at the end of that description.

One curtain driving means according to the present invention, and various modified forms thereof, as used in relation to different forms of curtain suspension track, will now be described by way of example and with reference to the accompanying diagrammatic drawings.

Brief description of the drawings

Figure 1 shows in front elevation a window opening in a wall, which opening is to be covered by a pair of curtains, and the relative dispositions of the various items

_* _- constituting the curtain driving means;

Figure 2 shows in plan view the disposition of some of those items, disclosed in relation to one form of curtain suspension track; Figure 3 shows to a different scale and iri a pictorial manner the curtain driving means applied to a different form of curtain suspension track, with the drive unit shown, for simplicity's sake, in side elevation; Figure 4 shows an enlargement of a belt clamp which is shown

encircled in the Figure 3;

Figure 5 shows pictorially an alternative form of belt clamp for use in place of that shown in the Figure 4;

Figure 6 shows pictorially an alternative form of belt-end fastening means for substitution in place of said belt clamps; and

Figure 7 shows, in a view similar to that of Figure 1, the application of such curtain driving means to a plurality of window openings spaced apart along a common wall.

Modes for carrying out the invention

Referring now to the drawings, Figure 1 shows a window opening 10 in a wall 12 that is to be provided with a pair of curtains, which are represented in chain-dotted form at references 14 and 16. A curtain suspension track is likewise shown in chain-dotted form at reference 18, being secured to the wall over and spanning the opening 10. The track is provided with a _^ plurality of suspension runners (Fig.2, 20; Fig.3, 22) for receiving curtain hooks (Fig.3, 24) which are engaged in the upper parts of the curtains. As will be seen from the Figures 2 and 3, the track comprises a single, full-length rail or rod carrying all the suspension members for both curtains. The curtain driving means that is about to be described in relation thereto would be equally useful in relationship to an alternative suspension track that comprises two half-length rails or rods which overlap at the centre of the span, or a plurality of such sets of half-length rails or rods.

The curtain driving means includes on the left hand side of the window opening 10 a drive unit 26 disposed in a position, largely below the curtain track 18, where it is concealed at all times by the left hand curtain, and on the right hand side of the opening 10 a belt return unit 28 which is mounted behind the right hand end of the curtain track 18 and which is concealed by the right hand curtain 16, likewise at all times.

The drive unit 26 comprises a base 30 on which are carried a high-ratio, speed-reducing gear unit 32, and a reversible, high-speed, electric driving motor 3 which is coupled to an input shaft (not shown) of the gear unit. An elongate output shaft 36 of the gear unit is journalled in a bearing extension 38 of the base 30 and carries at its free end and drives a toothed and flanged driving pulley 40.

The belt return unit 28 comprises a bracket 42 secured by screws 44 to the wall 12, a vertical stub shaft 46 carried on that bracket and being slidably adjustable thereon in a transverse direction along a slot 48, and a flanged, cylindrical belt-return pulley 50 mounted for rotation on that stub shaft.

Stretched tautly over the toothed driving pulley 40 and untoothed return pulley 50 is a continuous belt 52 in the form of a closed loop of a thin, broad, toothed, substantially inextensible belt material. That loop comprises two similar half-portions 54, 56 joined together with overlapping end portions 58, 60, the teeth 62 on one half-portion 54 (the driving portion) projecting inwardly and engaging the toothed driving pulley 40, and the teeth 62 on the other half-portion 56 projecting outwardly, so that the non-toothed side of that half-portion engages the cylindrical surface of the return pulley 50.

Each pair of overlapping end portions 58, 60 of the belt half-portions is clamped, with the respective sets of teeth of those portions inter-engaged, by means of a clamp 64 in the form of a thin shell 66 of square section, in which a pressure plate 68 is urged against the said end portions by a clamping screw 70 which is screwed through the shell wall. That clamping screw carries a ring-shaped head 72 through the eye of which is looped a flexible draw loop or link 74 for engaging at its free end around the lower part of a said curtain suspension member 22, in the manner indicated in chain-dotted form at reference 76 in Figure 3. By means of such draw links, the belt is coupled to selected curtain

suspension members 22 (or even to the curtain hooks carried thereby), so that on rotation of the belt driving pulley 40, the curtains are driven in appropriate directions. It will be appreciated that since the two draw links 74 shown are coupled to the respective clamps 64 that are associated respectively with the front and rear belt runs, the two sets of clamps and associated links move in opposite directions when the belt is driven by the belt driving pulley.

Other forms of clamp may be used instead of those shown in the Figures 3 and 4. For example, in Figure 5 the clamp 78 comprises a deformable metal clip 80, generally of U- shape, which has been slid over and then plastically compressed on to the opposed end portions of the belt half- portions, whereby to secure them together. The draw link 74 is looped through apertures 82 formed in the lower free ends of the clip.

Instead of using plastically deformable clips as described above, each such clip may be made instead of a metal or a plastics material that is resiliently openable from a closed, clamping position, so as to enable it to be slipped over the opposed end portions, whereafter it is allowed to snap back to its closed condition, and so hold those end portions secured together.

Alternatively, a U-shaped clip (of metal or a plastics material) may be provided with catch parts on the respective free ends of the clip, which catch parts may be caused to inter-engage after closing the clip on to the opposed end portions, and so hold the clip closed thereon.

Toothed, fibre-reinforced belt materials with very low extension rates are commercially available, and such belt materials can be adequately tensioned so that with the broad dimension of the belt material extending vertically very little downward deflection of the belt loop can be observed. Thus, the curtain driving belt loop appears substantially linear in front view, and does not droop across the window

<_

-9- opening in an unsightly manner.

Thus, with a curtain track of the kind illustrated in the Figure 3, the belt driving loop can be hidden from view behind the curtain track, in the manner shown.

Though toothed belt material cooperating with a toothed driving pulley (as shown in the Figure 3) is greatly advantageous, belt material not having teeth may be used instead, in which case the belt driving pulley may have a cylindrical belt-contacting surface.

The elongate drive pulley shaft 36 and the upward extension of the base 30 of the drive unit 26 enable (a) the belt loop 52 to be positioned as high as possible and even behind the curtain track in appropriate cases, so as to be obscured from v _^ iew; and (b) the motor and i,ts associated gear unit to be positioned lower down away from the curtain track, where there is more space to accommodate them.

Moreover, the adoption of a driving mechanism involving a high-speed motor (for example, one having a no-load speed of 8000 RPM) and a high-reduction-ratio gear unit results in a drive unit 26 of suitable size and proportions, such that it may be satisfactorily accommodated behind the curtain in the desired location near the curtain track 18.

The reduction in size of the driving motor is facilitated by the use of a low-voltage motor supplied through its own voltage-reducing transformer. Moreover, the use of a low- voltage motor also reduces the risk of electric shock to the person fitting or adjusting the curtain driving system to a curtain installation.

In the Figure 2, the curtain track is of the kind in which a large diameter cylindrical pole 84 is carried by two end brackets 86 secured to the wall 12, and the suspension runners 20 comprise large diameter rings carried on the pole and having, lowermost, small suspension eyes for receiving

curtain hooks such as those indicated in Figure 3 at reference 24.

In Figure 3, the curtain track comprises a thin strip 88 standing on edge and supported at intervals by mounting brackets 90 secured to the wall. The suspension runners 22 engage around the upper and lower edges of the strip 88 in the manner shown, and have eyes for receiving the curtain hooks 24.

The curtain drawing system described above can be supplied at relatively low cost to the purchaser (compared to the costs of the prior art systems). Moreover, it can be fitted to any set of curtains, whether existing or new, since there is no -special adaptation required to suit it to the particular circumstances of the curtain suspension installation, beyond the selection of appropriate lengths of belt material so as to suit the particular span of the curtains. »

It will be appreciated that the installation of the curtain drawing system described above is relatively simple to accomplish, and requires no special expertise. Furthermore, it will be appreciated that the positions of the drive and return units 26 and 28 may be readily interchanged to suit the particular circumstances of a given curtain installation, for example, where the power supply is situated on the opposite side of the window opening 10.

Though in the above description the driving motor has comprised an electric motor, other forms of reversible motor may be used instead.

Other forms of positive-drive belt and belt-driving pulley may be used instead of the toothed belt and pulley described above. For example, a belt having uniformly spaced apertures may be arranged to cooperate with a driving pulley having spikes or projections spaced apart uniformly around its circumference.

In a modification of the system described above with reference to the Figures 3 and 4, the belt clamps 64 are omitted, and as shown in the Figure 6, one end of each of the belt half-portions 54, 6 is provided with a buckle 100 for receiving and securing in a non-slip manner the other end of the other belt half-portion. That buckle comprises a closed buckle loop 102 secured permanently to the looped end of one belt half-portion 54, and a movable cross bar 104 which is slidably mounted on the side portions of the loop 102 and around which the free end of the other belt half- portion 6 is looped in the re-entrant manner shown, so as to trap itself securely between the transverse free end portion of the buckle loop 102 and the cross bar 104.

With such a modified belt system, the length of the belt can be readily adjusted by means of the buckles 100, so that the return pulley 50 can be mounted on a vertical shaft 46 that is non-adjustably fixed on th bracket 42.

4* A vertical pin or projection may be provided on that bracket 42 for temporarily holding one end of one such belt half- portion 5 , 56 whilst that belt half-portion is stretched across to the drive unit pulley 40 so as to determine the required length of that belt half-portion. For that purpose, the said buckle 100 may be temporarily impaled on said pin or projection so as to hold the associated end of the belt half-portion whilst that belt half-portion is stretched across to the driving pulley 40.

In a further modification, each said flexible draw loop or link 7 is formed as a simple piece of cord on one end of which is permanently secured a smaller version of the buckle 100. By adjustment of the position of the free end of the cord in the buckle, the length of the draw link can be read- ily adjusted to suit the particular arrangement of curtains and track. Each such buckled draw link 74 may be connected with the belt 52 by looping it through the closed buckle loop 102 of the relevant buckle 100 in the manner shown.

In the above described embodiments the curtain driving loop 52 has comprised two similar pieces of belt material joined in various ways as described. However, where a suitable belt material is commercially available in a length sufficient to provide such a continuous loop in one single piece only, to suit a desired window span, such a one-piece loop is preferred, and may be formed by permanently securing a buckle, such as that referenced 100 in the Figure 5, to one end of the belt material, for example, in the manner indicated in that Figure, and then threading the other end of that piece of belt material through the free end of the buckle and adjustably securing it there, for example, in the manner shown in that Figure. After forming that single- piece continuous loop in the manner described above, and engaging it loosely around the driving and return pulleys 40 and 50, the belt is tightened by drawing the free end of the belt material further through the buckle. When a toothed belt material (as used in the other embodiments) is used to form such a continuous one-piece loop, the teeth all face inwardly of the loop, and in that case preferably both the driving and the return pulleys are toothed pulleys.

In the past, toothed, fibre-reinforced belt materials with low extension rates have been available only in the form of continuous belts, such as have been used as for timing purposes in various forms of engine or other machine. Hence, the maximum available length of such toothed belt material has so far been determined by the maximum available size of such a continuous belt. That limitation on the maximum length of belt material has so far dictated, for all but the smallest window spans, the use of a two-piece curtain driving loop. However, by the use of recently devised, special production methods, it is now possible to produce such toothed belt material in much greater lengths than hitherto. Hence, it will be more convenient and cheaper to produce one-piece, toothed, curtain driving loops.

Where one-piece curtain driving loops are used, the leading ends of the respective curtains may be coupled to the

curtain driving loop 52 by means of flexible draw links such as those illustated at reference 74 in the Figures 3 and 4. Such draw links may be looped around the toothed belt material 52 itself at desired positions, or otherwise looped around suitable clips which are removably positioned on the belt material at those desired positions.

Whereas in the above described embodiments the curtain driving means have been illustrated and described as driving but a single pair of curtains across a single window opening, such curtain driving means may alternatively be arranged to span a plurality of similar window openings that are spaced apart along a single wall, and to simultaneously operate in that case the various pairs of curtains that are associated with the respective window openings. That may be achieved by similarly coupling each left hand curtain in like manner to, for example, the front run of the curtain driving loop 52, and each right hand curtain in like manner to, for example, the rear run of. that driving loop. ^' Such an arrangement is shown diagrammatically and by way of example in the Figure 7.

Though in the arrangement of Figure 1 the electric driving motor is supplied via a plug 104 which incoporates a transformer and the associated reversing switches, other embodiments may use a remote switch-control device having for example either a trailing cable linked to the plug or an infra-red transmitter link.

In contrast to the bulky prior art arrangements referred to in the introduction to this description, the driving and return pulleys 40 and 50 need have a diameter of only 12 mm. , as compared with the much larger pulleys of some 35 mm- diameter used in those bulky prior art arrangements.

We are aware of the following prior British patent specifications, namely:

563,499 (WILTSHIRE); 991,543 (FRENCH); and 1,045,250 (OVER)

In contrast to the disclosures of those specifications, it should be noted that the present invention provides a curtain driving means that (a) is quite independent of the curtain track or rail system on which the curtains are, or are to be suspended; (b) can be fitted to any existing or new curtain installation without alteration of that installation; (c) requires between the driving and return units 26 and 28 no intermediate supports or channels for supporting the weight of the continuous driving loop 2 so as to prevent it sagging in an unsightly manner; and (d) has good curtain driving characteristics.