WO2010107376A1

WO2010107376A1 - Multiple layer fabric

Info

Publication number: WO2010107376A1
Application number: PCT/SE2010/050288
Authority: WO
Inventors: Siw Eriksson
Original assignee: Siw Eriksson
Priority date: 2009-03-16
Filing date: 2010-03-16
Publication date: 2010-09-23
Also published as: EP2408957A1; EP2408957A4; EP2408957B1; SE534293C2; SE0950160A1

Abstract

This invention relates to a three-dimensional multilayer woven fabric comprising at least two woven layers extending substantially parallel to each other whereinsaid woven fabric further comprises at least one woven interconnecting structure interposed between the at least two layers and being arranged to connect the at least two layers to one another, which interconnecting structure comprises warp yarn arranged to extend between and integrate with said two respective layers in an alternating manner.

Description

MULTIPLE LAYER FABRIC

TECHNICAL FIELD This invention relates to a three-dimensional multilayer woven fabric comprising at least two layers extending substantially parallel to each other. The invention also relates to a method for producing a multilayer woven fabric.

BACKGROUND ART It is previously known to use stuffing within upholstery industry, where upholstery may refer to the work of providing furniture, especially seats, with padding, springs, webbing and fabric covers. In addition, an upholsterer may apply to domestic furniture as well as to applications in automobiles and boats. Various procedures of producing upholstery apply to various fields. For instance, when designing seats for automobiles a supporting metal frame, virtually corresponding to the shape of the seat, is covered with an injection molded foam, usually made out of polyurethane. The layer of polyurethane is then draped with an additional cover of composite fabric which generally consists of a lower base material, a middle layer of foam padding (made out of polyurethane) and an outer cover of thin tricot fabric. Said composite fabric is put together by means of lamination or gluing; a procedure which is quite laborious as well as time consuming.

Also, having a substantial portion made of polyurethane the foam material within these composite fabrics cannot be recycled. An example of such laminated material is presented in US 2005/0214511.

Another type of material is shown in patent US 4,379,798 wherein is shown a three- dimensional integral woven reinforcement for structural components which are applicable within airplanes, ships and automobiles. The material in US 4,379,798 is formed as an integral woven assembly of warp and fill yarns, with tie yarn passing from one side of the layer to the other. The fabric is arranged in a certain shape whereupon it is impregnated with resin in order to form the desired structural component. A material according to US 4,379,798 would not be suitable as upholstery fabric since its quality is robust and primarily adapted to act as a spacer that is rigid and has a fixated structure.

An increasingly important area within the field of material science concerns the development of smart textiles, meaning fabrics that assume additional function/s over the conventional purpose. For instance by integrating conductive filaments a material may be heatable and/or could be provided with a function of e.g. sensing humidity or measuring temperature. A known problem within this technical field is how to protect the conductive parts within the fabric (or any functional filament) from outer wear and tear that would disturb or even harm the function.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve or at least to minimise the above mentioned problems. This is achieved by means of a three-dimensional multilayer woven fabric comprising at least two woven layers extending substantially parallel to each other wherein said woven fabric further comprises at least one woven interconnecting structure interposed between the at least two layers and being arranged to connect the at least two layers to one another, which interconnecting structure comprises warp yarn arranged to extend between and, in an alternating manner, being integrated with the respective two adjacent layers. Preferably, but not necessarily, said interconnecting structure also comprises weft yarn. The interconnecting structure may also be referred to as an "interconnecting middle layer", "interconnecting layer" or "intermediate layer".

The interconnecting layer comprises a plurality of distancing layers each whereof is extending between the at least two adjacent layers, and wherein said distancing layers are arranged to distance the two adjacent layers from each other. Further said distancing layers comprises warp yarn extending substantially perpendicularly to the planes defined by the adjacent at least two layers.

When producing the fabric according to the invention the at least two layers and the interconnecting middle layer are woven simultaneously in one step, meaning a multiple layer fabric is acquired directly from the loom.

Several advantages are achieved thanks to the inventive multiple layer fabric, which comprises at least two layers (a first upper and a second lower layer) connected and stabilized by an intermediate interconnecting structure. According to one example of the invention the interconnecting structure represents a middle supporting layer within the fabric which stabilizes two adjacent outer layers, and at the same time keeps the fabric flexible and soft. Hereby the multilayer fabric is perfectly suitable e.g. as upholstery material e.g. for furniture, car seats and/or mattresses, and could thus readily replace any conventional laminated composite material. Being woven in one step a multilayer fabric may be collected directly from the loom and brought to e.g. an upholster and/or other manufacturers, virtually without any need of other ensuing treatments prior to further use. In particular, laborious lamination and/or gluing procedures are excluded from the making of the fabric which saves working time and cuts the cost of making upholstery material.

Moreover, the materials that are chosen for weaving the fabric according to the invention are preferably recyclable, meaning that the material provides an environmental friendly alternative to present composite fabrics.

Another advantage brought by the inventive fabric is that the woven material will provide outer layers which are rigid and wear resistant, and at the same time may provide a dense and smooth surface, which is a required property in particular for materials that are meant to form a sitting area of e.g. a couch, an armchair or a car seat.

In addition, each or all of the many layers may comprise yarn that provides a certain utility, e.g. yarn that is conductive, which would lead to a fabric that is associated with a function. If, for instance, such a conductive yarn would be integrated within the middle layer of the fabric according to the invention, these yarns are shielded from outer wear which helps to avoid short circuits and/or prolongs the lifetime of the functionality of the smart textile in question.

Each of the at least three layers (e.g. the upper, middle and lower layers) in the fabric according to the invention is woven independently, but simultaneously, in a weaving machine, meaning that for instance the quality of the yarn as well as the thickness and design of the respective upper, intermediate and lower layer may be chosen individually. The upper side surface design and the lower side surface design of the multilayer fabric may be composed out of two designs different from each other. This leads to a large number of possible variations of fabric design and quality which enables for adaption thereof to particular needs. For instance, if the multiple layer fabric is supposed to cover an office chair the layer of the fabric which will be facing outwards may be woven with a certain pattern, in a specific colour or in a quality that for instance is made particularly smooth and soft, in order to render a comfortable seat. At the same time, thanks to the inventive weaving method, the innermost layer of the fabric could be woven in a less expensive material and/or be more/less rigid compared to the outermost layer. Another area of application of the multiple layer fabric is in the field of interior architecture, especially due to a capacity of absorbing sound waves. As a result of the many layers the fabric can be designed to dampen sounds, for instance by providing the intermediate layer with a bulky yarn type, which makes it suitable to act as wall and/or ceiling cover. Furthermore, the outer layers of the fabric may be designed and patterned an any way possible within a weaving process. Thus, the fabric would be suitable to for instance partially drape walls and ceilings within a room, thereby providing decorative details and at the same achieve a less noisy environment since the fabric will readily absorb parts of emitted sound waves.

It is possible to create a multilayer fabric according to the invention with more than three layers, as previously described. In such an arrangement said three-dimensional multilayer woven fabric may for instance comprise three layers extending substantially parallel in such a way representing one upper, one middle and one lower layer, said upper and middle layers representing one pair, and said middle and lower layers representing another pair, wherein each pair of parallel layers is connected by an interconnecting structure in the form of an interconnecting layer. Each of the two interconnecting layers in the given example, in their turn, is arranged to undulate between, and be integrated with, one of said pair of layers during the weaving process, thus forming a plurality of distancing layers. Said three layers and said two interconnecting layers of the present example are woven simultaneously in a loom during the manufacturing process, creating a fabric with five layers, each layer which may be designed individually from the other ones, and still the whole entity is manufactured in one single manufacturing procedure.

The five layers as referred to in the above given example would be: a first upper layer, a second interconnecting layer, a third mid- layer, a fourth interconnecting layer and a fifth lower layer. Such a fabric may be used e.g. as a functional material, where conductive threads may be integrated within one of the inner layers (i.e. within either of the interconnecting layers, or within the third mid-layer) which means conductive threads are protected from outer wear and tear at least by the uppermost and lowermost layers.

It is understood that by "yarn" means any kind of yarn, thread or other suitable filament or fiber that may be used for weaving. Yarns to be chosen in the present invention may be selected depending on the using purpose. Examples of suitable yarns include, in addition to monofilaments, multifilaments, spun yarns, bulky yarn or stretchy yarn. The material of the warp and weft yarns used in said layers of the fabric can be selected freely and usable examples include polyester, nylon, cotton, wool and metal.

According to yet another aspect of the invention each of said interconnecting layers consists of a continuous woven layer arranged to be folded back and forth between two adjacent layers by means of weaving. Hereby the interconnecting middle layer will be arranged to undulate (i.e. it will have a wavelike form) in between the adjacent upper and lower layers.

The interconnecting structure, in the form of an undulate layer, comprises warp yarn and preferably also weft yarn, meaning it is a woven material where the weaving takes place simultaneously to weaving the other layers that constitute the fabric. It is understood that "undulate" said continuous layer refers to that the woven intermediate layer is brought to be alternately attached to, and by means of weaving integrated with, the upper and the lower layers respectively during the process of weaving.

Preferably, the material of the warp yarns used in said interconnecting structure is a resilient material, such as polyester or nylon.

The material of the weft yarns used in said interconnecting layer can be selected freely depending on the purpose of use. Examples of appropriate materials for weft yarns in said interconnecting layer may include metal, optic fiber, polyester, cotton, wool and other manmade materials such as polyvinylidene fluoride, polypropylene sulfide, polyethylene naphtalate.

During weaving, the warp of the middle interconnecting layer will alternate between, firstly, attaching to the adjacent upper layer and, secondly, attaching to the adjacent lower layer of the fabric hereby forming an undulatory structure. This results in a number of interconnecting bridges from one layer to the other, also called distancing layers. The resilient property of the warp within said interconnecting bridges will give the structure both a supporting and a stabilizing function, but will also at the same time allow a certain softness to the material.

The intermediate interconnecting structure and its distancing layers will be substantially covered by the adjacent layers of the fabric. In particular the weft of the intermediate layer will be completely protected from the outer surroundings, which is especially advantageous for certain types of yarns that might be sensitive to touch and wear. An example would be conductive filaments or conductive materials that may be integrated within the fabric creating a system which provides the function of a sensor. A sensor function may be e.g. to heat the material, register pressure, humidity or temperature. If such functional filaments would be introduced as a weft within the interconnecting layer, these filaments would be completely and effectively protected from the outside by the surrounding layers of the fabric.

According to yet another aspect of the invention, said fabric may be designed to comprise a particularly high absorption factor. It is understood that "absorption factor" refers to the quality of being absorptive, meaning the capability of absorbing e.g. a sound wave. By creating an interconnecting structure which comprises bulky weft yarns an intermediate layer with a high absorption factor is provided. Preferably, said multilayer fabric will provide an absorption factor between 0,4 - 0,8 for 500 Hz, and between 0,7 - 1,1 for 1 - 5 kHz.

It is understood that a multiple layer fabric may comprise one or more than one interconnecting layer, which interconnecting layer/layers may connect one or several pairs of layers, and where each interconnecting layer may or may not comprise functional filaments.

BRIEF DESCRIPTION OF THE DRAWINGS

The fabric and method of weaving the same will hereinafter be described in more detail with reference to the appended figures. The following description should be considered as preferred form only, and is not decisive in a limiting sense.

Fig. Ia is a perspective view showing a piece of multiple layer fabric according to one example of the invention;

Fig. Ib is a detailed view according to Ib of Fig. Ia; Fig. Ic schematically shows a portion of a side of the multiple layer fabric according to one embodiment of the invention; Fig. Id schematically shows a portion of a side of the multiple layer fabric according to another embodiment of the invention;

Fig. 2a is part of a cross sectional view taken somewhere along the line Ha of fig. 1;

Fig. 2b-2c each shows a part of a cross section of another example of the multiple layer fabric; Fig. 2d shows part of a cross section of another example of the multiple layer fabric; Fig. 3a is part of a cross sectional view taken somewhere along the line Ilia of fig. l; Fig. 3b-c each is a part of a cross section of the fabric according to another example of the invention;

Fig. 3d shows part of a cross sectional view taken along the line IHd of fig. 2d;

Fig. 4 is an example of a design diagram showing a repeating unit a multiple layer fabric according to the present invention; Fig. 5a and 5b include cross sectional views taken along lines Va-Vd at weft 1 '-4' over warp 1-16 illustrated in fig. 4 respectively; Fig. 6a and 6b includes cross sectional views taken along lines VIa-VId at warp 13-16 over weft l '-42' illustrated in fig. 4 respectively; and

Fig. 7a and 7b is an example of how a system of warp yarns may be organized in a fabric according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 schematically shows an example of a piece of multiple layer fabric 1 according to the invention where said piece comprises an uppermost surface 13, a lowermost surface 14, a short side 2 and a long side 3 where the short side 2 represents the side that is determined by the width of the loom wherein the fabric is produced, and the long side 3 represents the longitudinal side which elongates out from the loom as the weaving proceeds.

Further, the fabric according to the example of fig. 1 comprises two layers that extends substantially parallel to each other: one upper layer 10 and one lower layer 11. Each of said layers 10, 11 within the three-dimensional multilayer woven fabric 1 comprises warp yarns and weft yarns directed along a first and a second direction respectively which first and second directions are substantially perpendicular to one another in accordance with a conventional woven fabric.

The upper 10 and the lower 11 layers are interconnected by a middle intermediate structure 12 which is arranged to zigzag between the upper 10 and lower 11 layers thus forming a plurality of distancing layers 121 each extending between the two layers 10, 11. As is seen at the long side 3 of the piece of fabric in fig. 1, and as will be more thoroughly explained in connection to further figures 2a-2d, the interconnecting structure 12 is in the form of a woven continuous layer that is attached to, and directed back and forth between, the two adjacent upper 10 and lower 12 layers of the fabric 1 thus forming an undulatory structure.

Said interconnecting structure 12 of said woven fabric contains warp yarns 122 extending substantially along a direction substantially perpendicular to the planes defined by said upper and lower adjacent two layers 10, 11. Thus, the warp yarns 122 of the interconnecting structure 12 are extending in such a way crossing the planes that are defined by each of the adjacent at least two layers 10, 11, and ties the at least first 10 and the second 11 layers together.

The attaching of the intermediate interconnecting layer 12 to the adjacent layers is carried out during the weaving procedure, wherein the interconnecting layer 12 is woven simultaneously with the upper 10 and the lower 11 layers. The warp of the woven interconnecting layer is alternatingly integrated with the warp of the upper 10 and the lower 11 layer respectively, preferably forming distancing bridges 121 in between the two. Said resulting bridges 121 (also referred to as distancing layers) are extending between the upper 10 and the lower layers 11, however, it is to be understood that the plurality of distancing layers 121 are all part of a continuous layer preferably consisting of warp and weft.

It is equally possible to let the intermediate layer 12 alternate between being an integrated part of the upper 10 and the lower 11 layers without forming any distancing bridges there between, in which example of the invention the upper 10 and the lower 11 layers are arranged closely connected parallel to each other and attached by the intermediate layer 12.

The encircled enlargement Fig. IB of a corner piece of fabric 1 in fϊg.l shows that the interconnecting layer 12 is connecting the upper 10 and the lower 11 layers to each other, at the same time represents a plurality of distancing layers 121. Furthermore, the figure shows that the interconnecting layer 12 in the given example comprises warp 122 and weft 123 yarns. The weft yarns 123 of the intermediate layer 12 are protected by the upper 10 and the lower 11 surfaces respectively.

The weft 123 of said intermediate layer 12 is preferably composed by a manmade material, such as polyester threads, or any other resilient material which will provide stability and yet allow a certain springiness to the fabric. It is understood that by "springiness" means that the fabric will return to its original shape after having been compressed.

The general principle of weaving according to the invention is illustrated in the schematic Figures, lc-d, wherein is shown an example of how a warp yarn 122 of the interconnecting middle layer 12 is arranged in relation to the adjacent upper 10 and lower 11 layers respectively. In the figure is shown, in cross section, the weft yarns 100 of the upper layer 10 and weft yarns 110 of the lower layer 11 respectively. For clarifying reasons no warp yarns of the upper and lower layers 10, 11 are shown. Further, in a longitudinal section, there is shown a warp yarn 122 pertaining to the interconnecting middle layer 12 alternating between attaching to the adjacent upper 10 and lower 11 layers respectively thus forming an undulatory structure in a longitudinal direction. As is clear from looking at Figs, lc-d the warp 122 of the middle layer 12 is arranged to attach to the adjacent layers by means of binding to the weft yarns 100, 110 of the adjacent layers 10, 11 in an alternating manner.

Also shown in cross section are weft yarns 123 of the interconnecting middle layer 12. The interconnecting middle layer 12 separates the outer adjacent layers 10, 11 by distance d. In the example of Fig. Ic the warp 122 and weft 123 of the middle layer 12 are seen to be aligned to form a criss-cross pattern, typically referred to as "plain weave". However, a person skilled in the art will understand that many other alignments are possible and that the choice of how to align the warp 122 and weft 123 yarns within the middle layer 12 depends on the desired function of the final fabric. For instance the alignment shown in Fig. Ic may be advantageous if it is desirable to achieve a highly absorptive fabric since plain weave allows for a thick fabric with a large number of weft yarns 123 over a given distance. Another alignment is shown in Fig. Id, wherein a plurality of adjacent weft yarns 123 (here, three weft yarns) has the same alignment within the middle layer 12 and are woven together on the same side of the warp yarn 122. Such a configuration may be preferred in order to achieve a resilient fabric suitable for e.g. upholstery since the alignment of the weft yarns 123 allows for compression of the three layers 10, 11, 12 in the vertical direction, that is, thanks to the presented alignment the weft yarns 123 will not prevent the warp yarn 122 from getting compressed, nevertheless the weft yarns 123 will still provide a certain stability to the middle layer 12. Furthermore the warp 122, being preferably made from a resilient material will provide stability and yet allow a certain springiness to the fabric meaning the fabric will return to its original shape after having been compressed. Fig. 2a shows a part of a cross section taken somewhere along line Ha of fig 1. This figure further clarifies that the intermediate interconnecting layer 12 alternates between attaching to the upper 10 and to the lower 11 layers. The overall thickness of the multilayer fabric is denoted T_tot, the thickness of the upper layer is denoted T₁, the thickness of the lower layer T₂ and the distance between the upper and lower layers is denoted d.

The distance d is predetermined before weaving is initiated and can be varied depending on the required qualities of the final fabric material. A part of the interconnecting layer 12 which extends between two adjacent layers over the distance d is referred to as a "distancing layer". A large distance d will lead to a higher flexibility in the structure whereas a short distance d will render the fabric more stable and rigid.

It is possible to design a fabric according to the invention wherein T_tot essentially equals Ti + T₂, which would mean that the intermediate layer 12 will alternate between being integrated as a warp of the upper 10 layer, and being integrated as warp of the lower 11 layer, having the function of holding the two layers together.

The thickness of the upper Ti and lower T₂ layers may be varied by means of choosing a thicker or thinner yarn for the warp and weft respectively when weaving that particular layer.

Fig. 2b is a cross section showing another example from a view corresponding to that of fig. 2a where an upper 10 and a lower 11 layer are connected to each other by a distancing interconnecting layer 12. The interconnecting layer 12 comprises a plurality of distancing layers 121 and is alternating between being attached to the upper and the lower layers respectively.

When weaving the fabric, the warp yarns 123 of the interconnecting layer 12 are integrated with a section of the layer whereto it is meant to be attached (e.g. the upper) prior to being transferred to the other layer (e.g. the lower) and attached in the same manner.

In the example of fig. 2b the multiple layer fabric 1 is woven with a less number of distancing layers 121 along a given length of the fabric compared to the fabric of fig. 2a, meaning that during weaving longer sections of warp 122 of the intermediate layer 12 are integrated within the upper 10 and the lower 11 layers respectively. Fig. 2c illustrates another example of a multilayer fabric according to the present invention, wherein three layers 10, 11, 15 extend substantially parallel to each other, said three layers being interconnected by two interconnecting structures 12, 12' whereof each comprises a plurality of distancing layers 121 (also referred to as distancing bridges). It is to be understood that the interconnecting layers within one type of multilayer fabric might be designed individually and independently of other layers. This means that for instance the middle layer 15 may be provided with conductive filaments, and that the surrounding interconnecting structures 12, 12' may be designed to protect such conductive filaments from e.g. short circuits and/or outer wear. This may be achieved e.g. by means of introducing bulky, non-conductive weft yarns within adjacent interconnecting layers 12, 12'.

Moreover, as is seen in fig. 2c, the distance between the upper and the middle layers di may be shorter than the distance between the middle and the lower layers d2, and it is equally possible to vary the number of distancing layers 121 along a given length of the fabric. All of the described variations of outlining the fabric according to the present invention will result in a certain quality of the fabric, where examples of such qualities might include high or low resistance, stability and/or rigidity respectively.

Fig. 3a shows a part of a cross section taken somewhere along line Ilia of fig 1. In this figure is seen how the interconnecting layer 12 extends between the two adjacent upper 10 and lower 11 layers respectively, the warp yarns 122 of the interconnecting layer 12 being directed essentially perpendicular to the direction of the warp yarns in the upper 10 and lower 11 layers respectively. As is seen in the example of fig. 3a the interconnecting layer 12 also comprises weft yarns 123 extending horizontally across the warp. These inner weft yarns 123 may be of any suitable material and may, for instance, have certain function which enables for a specific functionality. In fig. 3 a two weft yarns 123 are inserted in the distancing layer, whereas fig. 3b shows an example where a multiplicity of six weft yarns 123 are extending across the warp yarns 122.

It is understood that the number of weft yarns may be increased, and that the interconnecting layer may either consist of a thick fabric with dense weft and warp yarns or may equally consist of a layer of multiple juxtaposed warp yarns without, or with a few only, weft yarns. Each such variation of the fabric will give certain properties to the resulting final fabric product. For instance, in one version of the fabric where the interconnecting layer 12 comprises both a dense plurality of weft yarns 122, and a large number of distancing layers 121 along a given length of the fabric will provide a material will particularly good absorptive quality. In one example of the fabric it will have an absorption factor between 0,7 and 1,1 for frequencies between 1 - 5 kHz.

In fig. 3c is shown another example of a cross section of a multiple layer fabric according to the invention, where the cross section illustrates the fabric from a perspective corresponding to the perspective of fig. 3a, but showing a different example. Herein, a number of three layers 10, 11, 15 are extending substantially parallel to each other. The upper 10 and the middle 15 layers represent one pair, and equally the middle 15 and the lower 11 layers represents one pair. The layers of each pair are connected to each other by integrated woven interconnecting layers 12, 12'. Each of the two interconnecting layers 12, 12' comprises warp yarns 122, preferably polyester warp, and preferably also a number of weft yarns 123. In the example of fig. 3c it is possible that the uppermost interconnecting layer 12' acts as an insulator of the lowermost interconnecting layer 12, meaning any conductive filaments that exist within the lowermost distancing layers of the fabric will be shielded and protected from e.g. a short circuit by the uppermost interconnecting layer 12'.

Figs. 2d and 3d illustrates yet another example of a cross section of the fabric according to the present invention, which cross section 2d corresponds to the perspective of fig. 2a, and cross section 3d corresponds to the perspective of fig. 3a.

As is seen in fig. 2d the fabric is woven in such a way that the distance d between the upper 10 and the lower layers 11 is varied for each distancing bridge 121 of the intermediate layer 12. This is achieved by changing the length of the distancing bridges 121 of the intermediate layer 12 along the length of the woven fabric. The result of such a design is a fabric which presents a wave-formed profile. Such a fabric may provide advantages e.g. as sound dampening material, since the wavy surface will be facing different directions and will therefore absorb sound equally effectively no matter where the source of emitted sound is located in relation to the fabric itself.

Fig 3d shows a cross section of the same example as in fig. 2d, taken along line IHd of fig. 2d. An intermediate layer 12 creates a distance d between the upper 10 and the lower 11 layers, only in this example the distance d varies along the length of the fabric resulting in a wave formed uppermost surface 13 and a wave formed lowermost surface 14. In the example of fig. 3d the uppermost 13 and the lowermost 14 surfaces are linear along a direction corresponding to a direction across the short side 2 of a piece of fabric. It is possible to let this surface embrace a wave shaped form alike the undulate surface of the profile in fig. 2d.

Fig. 4 shows a design diagram representing an example of a repeating unit of a multilayer fabric according to the present invention. The fabric of the present example is a 16-shaft three layer fabric having an upper layer, an intermediate interconnecting layer and a lower layer, each layer respectively comprising warp and weft yarns.

The numerals of 1 - 16 denote upper layer warp, interconnecting layer warp and lower layer warp yarns and the numerals of 1 '- 42' denote upper layer weft, interconnecting layer weft and lower layer weft yarns.

Referring to numerals which denote the warp yarns, only 1 '- 4' and 39'- 42' are shown explicitly in fig. 4, however, it is understood that the numerals 5' - 38' are represented as well by the corresponding intermediate rows of the design diagram.

In the design diagram in fig. 4 indicated at numerals 4, 8, 12 and 16 are warp yarns of the interconnecting layer, indicated at numerals 1, 2, 5, 6, 9, 10, 13 and 14 are warp yarns of the upper layer and indicated at numerals 3, 7, 11, and 15 are warp yarns of the lower layer of the fabric according to the invention.

Furthermore, in the design diagram in fig. 4 indicated at numerals l'-3' and 25' - 29' are weft yarns of the lower layer, indicated at numerals 4' - 8' and 22' - 24' are weft yarns of the upper layer and indicated at numerals 9' - 21' and 30' - 42' are weft yarns of the interconnecting layer.

In this diagram a mark Δ means that an upper layer warp lies over an upper layer weft; a mark o means that a lower layer warp lies over a lower layer weft; the marks 0, c, Θ and / means that an interconnecting layer warp lies over an interconnecting layer weft; the mark ~ means weaving of weft within the lower layer; the marks - or • means weaving of weft within the upper layer; and ∞ means weaving of weft within the intermediate interconnecting layer.

When weaving a fabric according to the diagram of fig. 4 the weaving proceeds in the following way. Warp and weft yarn for each of the different layers (upper, intermediate and lower layers) are arranged within the weaving machine, and the warp yarns are brought through their respective heddles. When starting weaving the machine begins with the weft corresponding to numerals 1 ' and proceeds upwards according to increasing numerals: 2', 3', 4' and so on, up to 42'.

Firstly the machine will weave in the lower layer (1 '-3') after which it weaves in the upper layer (4'-8'). Then, weaving in the interconnecting layer will take place (9'-2T) and the warps of the intermediate layer is elevated by the corresponding shaft so that the warps are positioned above the upper layer and are integrated with the warp yarns of this upper layer. Again, weaving in the upper layer will proceed (22'-24'), followed by weaving in the lower layer (25 '-29'). Finally weaving in the interconnecting layer (30'- 42') and redirecting this layer by lowering the corresponding shaft to be part of the lower layer is concluding the cycle of the given example, which is then repeated.

Figure 5a is a cross sectional view taken along the lines Va and Vb in fig. 4 at weft yarns 1 ' and 2' respectively, where Va is represented by yarn 51 and Vb is represented by yarn 52.

In a similar manner, fig. 5b is a cross sectional view taken along the lines Vc and Vd in fig. 4 at weft yarns 3' and 4' respectively. Here, Vc is represented by yarn 53 and Vd is represented by yarn 54.

Fig. 6b is a cross sectional view taken along the lines Via and VIb in fig. 4 at warp yarns 16 and 15 respectively, where Via is represented by yarn 61 and VIb is represented by yarn 62. Moreover, fig. 6b is a cross sectional view taken along the lines VIc and VId in fig. 4, at warp yarns 14 and 13 respectively. VIc corresponds to yarn 63 and VId corresponds to yarn 64.

Figs. 7a and 7b are illustrating how a system of warp yarns may be arranged in order to create a certain functionality of the fabric. In these figures five warp yarns 125, 126, 127, 128, 129 represent a profile according to an example of the multilayer fabric.

Two yarns 125 and 129 represent the warp or the upper and the lower layers respectively, and three yarns 126, 127 and 128 represent warps that belong to the interconnecting layer of the fabric. (It is to be understood that in reality the interconnecting layer 12 comprises many more parallel warp yarns that are not shown in fig. 7a for clarifying reasons.) One warp yarn 126 is made out of conductive filaments, or out of a material constituting a mix between non-conductive and conductive materials. Examples of such materials may be carbon, silver, copper or other metals and/or alloys. When weaving the fabric the conductive warp 126 is brought to surface the fabric at certain limited regions whereby the warp yarns create a cushion 7 of conductive filaments. Cooperating yarns 127, 128 are brought along with said conductive yarn 126 and may surface with it e.g. in order to create a distancing structure 71 within said cushion 7 and/or provide isolation protection 127 whereby short circuits are avoided.

The result of such a design is a number of protruding conductive cushions 7 which are surfacing the fabric 1 at predetermined sites, where the locations of said sites are decided during the outline of a design diagram for weaving. A fabric according to this particular example is seen in fig. 7b wherein is shown the upper surface of a piece of fabric which is woven with a number of surfacing conductive cushions 7.

At the portions of the fabric where no conductive cushions are required the warps 126, 127, 128 are kept in between the warp yarns 125, 129 of the outer upper and lower layers 10, 11. A fabric with conductive spots, e.g. in the form of said cushions 7, may be used e.g. for sensing pressure on mattress covers in hospitals, where it may be important to monitor lying patients in order to avoid bedsores. In such an application the conductive cushions would represent electrodes that are brought into contact with the person as he/she lies upon the fabric with such an outline.

It is possible that a warp filament of the intermediate layer 12 never surfaces, but elongates in between the two adjacent layers 10, 11. Such a version may provide a way of heating the fabric from the inside. By adding a voltage over the conductive filaments the filaments will heat up, which in its turn will warm up the surrounding fabric.

Said conductive yarn 126 may be replaced by any kind of yarn, conductive or non- conductive, whereby the choice of having non-conductive yarns will still lead to a certain surface structure corresponding to surface comprising protruding cushions as shown in fig. 7b.

The invention is not to be seen as limited by the embodiments described above, but can be varied within the scope of the appended claims. For instance it is understood that the fabric may compose three, five or more layers which are woven simultaneously in accordance with the inventive method. Furthermore it is possible that all layers are woven of the same kind of material and, equally, that each of the respective layers is made out of a yarn type which is different from the other ones.

Claims

1. A three-dimensional multilayer woven fabric comprising at least two woven layers (10, 11) extending substantially parallel to each other characterized in that said woven fabric (1) further comprises at least one woven interconnecting structure (12) interposed between the at least two layers (10, 11) and being arranged to connect the at least two layers (10, 11) to one another, which interconnecting structure (12) comprises warp yarn (122) arranged to extend between and integrate with said two respective layers (10, 11) in an alternating manner.

2. A three-dimensional multilayer woven fabric according to claim 1, wherein said interconnecting structure comprises weft yarn (123).

3. A three-dimensional multilayer woven fabric according to claim 1 or 2 characterized in that said interconnecting structure (12) comprises a plurality of distancing layers (121) each whereof is extending between the at least two adjacent layers (10, 11), and wherein said distancing layers are arranged to distance the two adjacent layers (10, 11) from each other with a distance (d).

4. A three-dimensional multilayer woven fabric according to claim 3 characterized in that said distancing layers (121) comprises warp yarn (122) extending substantially perpendicular to the planes as defined by the adjacent at least two layers (10, 11).

5. A three-dimensional multilayer woven fabric according to claim 4 characterized in that said fabric comprises three layers (10, 11, 15) extending substantially parallel to each other in such a way representing one upper (10), one middle (15) and one lower (11) layer, said upper (10) and middle (15) layers representing one pair, and said middle (15) and lower (11) layers representing another pair, each pair of layers comprising an interconnecting structure (12, 12') with a plurality of distancing layers (121).

6. A three-dimensional multilayer woven fabric according to any of claims 1-5 characterized in that said interconnecting structure (12, 12') is a continuous woven layer arranged to extend back and forth between two adjacent layers (10, 11, 15) by means of a weaving process.

7. A three-dimensional multilayer woven fabric according to claim 7 characterized in that the warp yarn (123) of said interconnecting structure (12, 12') partially and discontinuously will be integrated with the warp of the adjacent two layers (10, 11, 15) respectively in such a way alternating between the upper (10) and the lower (11) layer respectively.

8. A three-dimensional multilayer woven fabric according to any of claims 1 - 7 characterized in that said warp yarn (122) within said interconnecting structure (12, 12') is made of a manmade yarn, preferably polyester monofilament yarn.

9. A three-dimensional multilayer woven fabric according to any of claims 2 - 8 characterized in that at least one of said weft yarns (123) within said continuous interconnecting structure (12, 12') is at least partially made out of a conductive material, such as copper, silver or carbon.

10. A three-dimensional multilayer woven fabric according to any previous claims characterized in that at least one of said warp yarns within any of said at least two layers (10, 11, 15) and/or within said continuous interconnecting structure

(12, 12') is made out of a conductive material, such as copper, silver or carbon.

11. A three-dimensional multilayer woven fabric according to any of previous claims characterized in that said interconnecting structure (12, 12') comprises a system of warp yarns (126, 127, 128) which may or may not protrude through the adjacent upper and/or lower layers (10, 11) of the fabric according to the invention.

12. A three-dimensional multilayer woven fabric according to any of previous claims characterized in that said woven fabric has an absorption factor of at least 0,4, preferably at least 0,7 and even more preferably at least 0,9 for 500 Hz.

13. A three-dimensional multilayer woven fabric according to any of previous claims characterized in that said woven fabric has an absorption factor of at least 0,5, preferably at least 0,7 and even more preferably at least 0,9 for frequencies between 1 - 5 kHz.

14. A method for producing a three-dimensional multilayer woven fabric comprising the steps of: providing a loom/apparatus for weaving; using the loom for weaving at least one first layer (10) of fabric; - using the loom for weaving at least one second layer (11) of fabric; characterized in that: said at least first (10) and second layers (11) are woven simultaneously within the loom; and at least one third intermediate layer (12) is woven within the loom simultaneously with the at least first (10) and second layers (11), which intermediate layer (12) is arranged to be continuously undulated in such a way back and forth between the adjacent first and second layers during weaving thus forming a plurality of distancing layers (121) which are integrated with, and are interconnecting, said two adjacent layers; and in that all of the above mentioned steps are carried out simultaneously within the loom to instantly produce a three-dimensional multilayer woven fabric (1).