The present invention relates to pocketed springs for an upholstered article or similar.

Pocketed springs, sometimes referred to as encased springs, are used in a variety of upholstered articles, such as mattresses. Mattresses in which the springs are encased in pockets of fabric are generally held to be more comfortable and luxurious than conventionally sprung mattresses. This is partly because discrete, independently acting pocketed springs are more able to conform to the shape of a person' s body than a mesh of interconnected springs in which the springs are unable to deform without affecting their neighbours. Also, the presence of the fabric pocket between adjacent springs lessens the likelihood that the springs will rub together, which can generate an unwelcome level of noise in what is meant to be a quiet environment. Broadly, there are two common types of pocketed spring unit. The first is of the type described in our PCT Patent application, published as WO 2007/031774, in which coil springs are located between axially spaced sheets of material, which sheets are welded or otherwise attached together at points between the springs to encapsulate the springs in individual pockets. This method produces an array of individually pocketed springs as a pocketed spring unit . The other type is made by encasing each spring in a pocket formed by folding a sheet of material and then welding or otherwise attaching together the leaves of the folded sheet along the side of the spring. The thus formed strings of springs are then stacked alongside one another and are glued at their ends, axially above and below the springs, to further sheets of material to form a pocketed spring unit .

Various types of material are used in the manufacture of the above-described pocketed springs, and particularly common is the use of non-woven, spun-bonded polyester, as this can readily be welded to itself using electrical welding apparatus.

The present invention is defined in the attached independent claims, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto.

According to another aspect of the present invention, there is provided a pocketed spring comprising a spring encased in a pocket at least partly formed from a non-opaque, weldable material.

According to another aspect of the present invention, there is provided a pocketed spring comprising a spring encased in a pocket at least partly formed from a woven, weldable material .

According to yet another aspect of the present invention, there is provided a pocketed spring comprising a spring encased in a pocket at least partly formed from a woven, non-opaque material. The invention also includes a pocketed spring unit comprising a plurality of springs encased in pockets according to any statement herein.

In a preferred arrangement at least some of the pocketed springs are attached at least at their one ends to a common sheet of weldable material .

The pocketed springs may be attached at their one ends to a first common sheet and may be attached at their second ends to a second common sheet .

The non-opaque material may comprise substantially translucent material, and/or substantially transparent material .

At least some of the pockets may be formed from material that is woven and weldable.

The invention also includes a pocketed spring unit comprising a plurality of springs encapsulated in one or more pockets formed between first and second sheets of material, which material is non-opaque and weldable.

The invention also includes a pocketed spring unit comprising a plurality of springs encapsulated in one or more pockets formed between first and second sheets of material, which material is woven and weldable.

The invention also includes a pocketed spring unit comprising a plurality of springs encapsulated in one or more pockets formed between first and second sheets of material, which material is non-opaque and woven.

The first and second sheets may be bonded, welded or otherwise joined together at spaced locations to form the pockets for the springs.

The springs may comprise coil springs and may be of wire. At least some of the springs may have coils of different diameters at opposed ends.

Preferably, in respect of at least some of the springs, the diameter of at least one of the coils is greater than the axial length of the spring in the pocket. For at least some of the springs the first and second layers may be joined together at a position that is closer to one end of the spring than the other.

The first and second layers may be welded together, for example ultrasonically or thermally. The weld may form a join that may be wider than it is tall, and is preferably substantially flat. In a preferred arrangement the pockets are formed from only the first and second sheets. For at least some springs the first and second layers of material may be joined at a position that is closer to an end of the spring having a coil of larger diameter.

Preferably substantially the same area of material is arranged to cover each end of the spring. In a preferred arrangement the unit is also at least partly compressible in at least one direction transverse to the axis of the springs. Preferably at least some of the springs are held under compression in their pockets.

The springs are preferably wire and are more preferably of steel, aluminium or titanium, or of an alloy thereof.

Preferably the unit is flexible in at least one lateral direction, generally perpendicular to the axis of the springs . The material may be translucent or transparent and is preferably breathable. More preferably at least a portion of the material may comprise holes or perforations.

In a preferred arrangement the material comprises a woven polymeric fibre such as polypropylene.

The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclusive, or mutually inconsistent.

Ά preferred embodiment of the present invention will now be described. By way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows in schematic perspective view a first embodiment of pocketed spring unit according to the present invention; Figure 2 shows the pocketed spring unit of Figure 1 in schematic sectional view; and

Figure 3 shows in schematic perspective view a second embodiment of pocketed spring unit according to the present invention.

Turning to Figures 1 and 2, there is shown generally at 10 a pocketed spring unit comprising a plurality of coil springs 12 each encased in its own individual pocket 14 formed between two sheets 16 and 18 of material. The sheets 16 and 18 have been welded at points 20 between the springs , so as to form the pockets.

One method for forming such a pocketed spring unit is described in our PCT patent application, published as WO 2007/031774, the entire contents of which are incorporated herein by reference.

In the embodiment shown, the material from which the sheets are made is polypropylene which in this case is woven. The material is weldable and breathable and in this example is also substantially transparent so that the springs 12 are visible within their pockets. In this embodiment the upper layer is also perforated with holes to allow air to circulate freely within the spring unit. In an alternative embodiment (not shown) the lower layer may be perforated, or both layers may be perforated.

Figure 3 shows another common type of pocketed spring unit, generally at 30. A plurality of individual coil springs 32 are each encased within an individual pocket 34 formed of the material described above in relation to the embodiment of Figures 1 and 2. A number of the pocketed springs 32 are formed together as a linear string of springs and the strings are then placed together and joined at upper and lower ends by sheets 36 and 38 of material by gluing or preferably welding the material of the sheets 36, 38 to the material of the pockets 34. Again, he upper sheet 36 or lower sheet 38, or both sheets, may be perforated.

The welding may be ultrasonic or thermal welding. The material, being woven, helps to deaden the noise made by the movement of the springs in use. In addition, as it is substantially transparent, the springs themselves are visible, which may be of interest to a purchaser. One or both of the sheets 16, 18 or 36, 38 may be nonopaque, such as translucent or transparent, or only a portion of at least one of these sheets may be non-opaque.

The upper and lower layers, or as the case may be sheets, may have different properties or characteristics, and may be combined in various ways. Examples include but are not limited to differences between the layers in respect of thermal characteristics, waterproofing, weight, density, water absorption or repellence, visual appearance, tactile properties, structural differences such as woven or non- woven, knitted, felted, wear characteristics, elasticity, antibacterial, anti-static, properties of flavour and/or fragrance and flame-retardance .

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.