Camouflage material

Abstract: There is disclosed an adaptive material (1) comprising a sheet, a plurality of members (4) having regions with different electromagnetic radiation absorbing and/or reflecting properties movably retained on or within the sheet such that portions of the members (4) are visible through apertures (3) in the sheet when the material is viewed in a direction perpendicular to the plane of the sheet and means for moving the members (4) such that different portions thereof become visible through the apertures (3). The overall appearance of the material is thereby changed. Also disclosed is an adaptive material in which the overall permeability of the material can be changed.

Description: This invention relates to adaptive material. In particular, the invention concerns materials which are able to adapt or to be adapted to their surroundings. Adaptive materials of this type may be used, for example, as camouflage. The benefits of materials which blend with their surroundings have long been recognised. US-A-5281451, its content is taken as basis for the preamble of claims 1 and 14 discloses an ultra-lightweight camouflage net system suited for tactical concealment of objects and equipment. However, a problem with most of the conventional materials of this type is that they are unable to adapt to a change in surroundings. For example, conventional green or brown camouflage fails to serve its purpose after heavy snow when the surroundings become white. Also, effective camouflage can become a hindrance rather than an advantage when the wearer of a camouflage suit needs to be rescued. The present invention relates to materials which can be adapted to their surroundings, referred to herein as "adaptive materials". It has been proposed to base adaptive materials on the use of chemicals which change colour under certain conditions either external (e.g., temperature) or under the control of a human operator. These materials can be expensive to produce, however, are sometimes slow to change colour and can have limited lifetimes. The present invention alleviates these problems whilst providing a material which is sufficiently flexible to form part of a garment. According to a first aspect of the present invention, there is provided an adaptive material comprising a sheet, a plurality of members having regions with different electromagnetic radiation absorbing and/or reflecting properties movably retained on or within the sheet such that portions of the members are visible through apertures in the sheet when the material is viewed in a direction perpendicular to the plane of the sheet characterised by means for moving the members relative to the sheet such that different portions thereof become visible through the apertures, thereby changing the overall appearance of the material in the visible or invisible region of the electromagnetic spectrum when viewed in the said direction. The sheet and the members are preferably arranged such that the portions of the members which are visible at any given position of the members relative to the sheet have the same electromagnetic absorbing and/or reflecting properties (hereinafter referred to as "optical properties"). Thus, for example, at any given time the portions of the members which are visible may be all green or all brown and, therefore, the overall appearance of the sheet may change from green to brown when the members are moved relative to the sheet. The members are preferably elongate and are movable relative to the sheet by rotation about their own axis. The members may be helical or substantially cylindrical with the regions having different optical properties preferably arranged as stripes extending lengthwise along the members such that as a member is rotated different regions can be seen, in turn. Preferably each member has at least three, more preferably three or four, regions having different optical properties. If each member has three such regions, for example, the overall appearance of the sheet may take three different forms (e.g., green, sand and white coloured). The sheet in the material of the invention preferably comprises a series of tubes connected substantially in a line along their longitudinal edges, each tube being capable of acting as a housing for a colour change member. The sheet is advantageously of fabric and may be produced as a double layer fabric with the connections between the tubes being formed either as part of the process in which the fabric is formed (e.g., by knitting or weaving) or by adhering the two layers to each other after the double layer fabric has been produced. The sheet comprises apertures through which the members are visible. Preferably, the apertures are disposed in a chequered arrangement on the sheet. By having the apertures in a chequered arrangement, the impact of the colour of the sheet itself on the overall appearance of the material can be minimised, thereby maximising the contribution to the appearance of the material which is made by the members. The sheet preferably has a neutral colour, such as a shade of light brown or grey, again so as to minimise the influence of the sheet on the overall appearance of the material. The apertures in the sheet are generally formed as part of the process for producing the sheet and are preferably on one side of the sheet only (although they could be on both sides of the sheet). In a preferred embodiment of the invention in which the sheet is of fabric, the apertures are formed in the sheet by spaces between groups of weft threads. By using groups of weft threads which pass over and under the warp threads and making neighbouring groups of weft threads 180° out of phase with each other, a chequered arrangement of apertures can be produced. The means for moving the members relative to the sheet preferably comprises a rod which runs along the edge of the sheet substantially perpendicular to the members. The members can then be made to move together by movement of the rod translationally along its axis or rotationally about its axis. Suitable methods for converting movement of the rod into movement of the members are well-known to those skilled in the art. The members may rotate completely about their longitudinal axis or only partially. The members may be moved by a human operator or, preferably, automatically in response to a change in the surrounding conditions (e.g., movement of the members is caused by a light or temperature sensor). The members may have gaps therein which enable the adaptive material to be used as a variable climate material, for example clothing. Thus, when the gap fully or partially coincides with the aperture, air, moisture, and/or heat can be transferred to or from the wearer thus providing a material which can adapt its thermal insulating properties according to its surroundings. Where the members are helical, rotational and translational movement is required in order to expose a portion of the member having different optical properties to the aperture. However, rotational or translational movement alone can also be useful because this can have the effect of bringing a gap in the helix into line with the aperture, preferably on both faces of the sheet simultaneously, thus providing a passage for air through the material. Hence, in particular members which are helical can provide a material which can be adapted in terms of its optical properties, as well as being able to vary its permeability. The regions on the members having different optical properties are preferably selected from regions which are coloured green, sand, brown or white and/or regions which are fluorescent, retro-reflective, radar and/or infra-red reflecting and/or absorbing. The optical properties may be due to the properties of the substance from which the members are made or may be provided by a coating which is applied to the members. According to a second aspect of the present invention, there is provided an adaptive material comprising a sheet, a plurality of permeability varying members retained on or within the sheet such that portions of the members are adjacent apertures in the sheet, characterised by means for moving the members relative to the sheet such that different portions thereof become adjacent the apertures, thereby changing the overall permeability of the material. One or more of the portions may be an air gap. Other preferred or alternative features are mentioned above. The material of the invention can be made to be flexible and is therefore particularly useful for a suit of clothing e.g., a camouflage suit. The material may form all or just a part of the suit of clothing. Alternatively, the material may form a camouflage cover, for example for stationary or mobile equipment or machines such as are used in military activities. Other uses of the material of the invention include displays, such as advertising hoardings which can be changed to show different advertisements, road signs and garments which enhance the visibility of the wearer e.g., jackets for workmen or cyclists. The invention will now be described, by way of example only, with reference to the accompanying drawings wherein: Figure 1 is a perspective view of adaptive material according to the invention, in partial cross-section; Figure 2 is a plan view of adaptive material of the invention; Figure 3 is a perspective view of a cylindrical member for use in the material of the invention; Figure 4 is a schematic end view of the cylindrical member shown in Figure 3; Figure 5 is a schematic view of a helical member for use in the material of the invention; and Figure 6 shows, schematically, an item of clothing which incorporates adaptive material of the invention. Referring to Figure 1, adaptive material 1 comprises a sheet in the form of a series of interconnected tubes 2. The sheet is preferably based on a woven or knitted double layer fabric although the sheet could equally be constructed in other ways from other materials (e.g., from sheet plastics material). Tubes 2 are formed from the double layer fabric by attaching one layer of fabric to the other at regular intervals across the sheet; this attachment of the layers of the double fabric preferably takes place as part of the weaving or knitting process for producing the fabric but can be effected in other ways (e.g., by heat sealing or otherwise adhering the two layers together). The sheet material is constructed such that each tube 2 has a plurality of apertures 3 on at least one face of the sheet material. Apertures 3 are preferably formed during the weaving or knitting process for producing the double layer fabric but can also be formed after the sheet has been produced (e.g., by cutting through one layer of the sheet). Where the sheet material is woven, apertures 3 can be made by gaps between groups of threads in the weft direction, with the groups of threads passing over a first tube 2 and then under its nearest neighbouring tube 2. In this way, a chequered arrangement of apertures 3 (as shown in Figure 1) can be attained. Members 4 are housed in tubes 2 such that portions thereof, spaced along the length of the members, can be seen through apertures 3. Members 4 are movable relative to tubes 2 by rotation within tubes 2 or by translation into and out of tubes 2. As shown in Figures 3 to 5, members 4, 4a are elongate and are preferably substantially cylindrical members 4 (Figures 3 and 4) or helical members 4a (Figure 5). Members 4, 4a have surfaces which have different coatings applied to them, each coating having different electromagnetic radiation absorbing and/or reflecting properties (e.g., different colours), the different coatings being illustrated in the figures by different hashed or dotted shading. The different coatings on cylindrical member 4 are arranged as stripes along the length of member 4. In Figure 4, a schematic end view of member 4 which has three different optical coatings is shown; the three coatings are arranged as stripes down the length of the member, each stripe forming the outer surface of a roughly 120° segment of member 4. Helical member 4a shown in Figure 5 has three different optical coatings around its helix. Helical member 4a can be formed by winding up a strip of material (e.g., plastics material) which has a series of bands having different optical properties. Alternatively, helical member 4a can be produced by applying coatings to a preformed helix. Although the members 4, 4a shown in Figures 3 to 5 have three coatings on their surface, it will be appreciated that they could equally have a different number of coatings e.g., two, four or more than four. With reference to Figure 2, material 1 comprises rod 5 which moves members 4 relative to tubes 2. Connectors 6 cause motion of rod 5 to be translated into movement of members 4 relative to tubes 2 and, when members 4 are cylindrical, can simply be pins rotatably attached to rod 5 and rotatably attached to members 4 at a point radially spaced away from the axis of members 4. Thus, translational motion of rod 5 in a direction along its length causes members 4 to rotate within tubes 2 and changes the portions of members 4 which are visible through apertures 3. Preferably, all of the members 4, 4a are moved at the same time such that the portions of the members 4, 4a which are visible through apertures 3 after members 4, 4a are moved all have optical properties which are different from those of the portions of members 4, 4a which were initially visible. The overall appearance of the sheet can therefore be altered by moving rod 5 and this effect is increased by having a chequered arrangement of apertures 3 as shown in Figure 2. The change of optical properties can be further enhanced, particularly where a change in colour is involved, by making the background sheet material (i.e., the parts of the tubes which are not apertures) a relatively neutral colour e.g., a light shade of brown or grey. Means for moving rod 5 is not depicted in Figure 2. However, this could simply be a manually operated handle, a bi-metallic strip or an electric motor triggered by a detector sensitive to a change in the environment (e.g., activated by a change in temperature or light intensity). When helical members 4a are used in the material shown in Figure 2, connectors 6 need to be adapted such that part of the helix remains visible through apertures 3. Therefore, connectors 5 are adapted (e.g., by a peg which engages the helix) such that movement of rod 5 causes member 4a both to rotate within tubes 2 and to move translationally along the length of tubes 2. However, if members 4a are simply rotated, gaps in the helix overlap with apertures 3, providing the sheet with greater permeability (e.g., to air); this ability to alter the permeability of the sheet can be important and, therefore, rod 5 and connectors 6 are preferably adapted to allow rotational motion alone or rotational and translational motion together of members 4a within tubes 2. Figure 6 shows an item of clothing, jacket 7, which incorporates adaptive material 1. In the figure, material 1 is formed as a single panel in or over jacket 7. However, jacket 7 could equally comprise a plurality of different panels on different parts of jacket 7.

Claims: An adaptive material (1) comprising a sheet (2), a plurality of members (4; 4a) having regions with different electromagnetic radiation absorbing and/or reflecting properties movably retained on or within the sheet (2) such that portions of the members are visible through apertures (3) in the sheet (2) when the material (1) is viewed in a direction perpendicular to the plane of the sheet characterised by means (5, 6) for moving the members relative to the sheet such that different portions thereof become visible through the apertures, thereby changing the overall appearance of the material in a visible or invisible region of the electromagnetic spectrum when viewed in the said direction. An adaptive material as claimed in claim 1, wherein the sheet (2) and the members (4; 4a) are arranged such that the portions of the members which are visible at any given position of the members relative to the sheet (2) have the same electromagnetic absorbing and/or reflecting properties. An adaptive material as claimed in claim 1 or claim 2, wherein the members (4; 4a) are elongate and are movable relative to the sheet by rotation about their own axis. An adaptive material as claimed in claim 3, wherein the members (4a) are helical. An adaptive material as claimed in claim 3, wherein the members (4) are substantially cylindrical. An adaptive material as claimed in any one of claims 1 to 5, wherein the sheet (2) comprises a series of tubes (2) connected in a line along their longitudinal edges, each tube being capable of acting as a housing for a colour change member (4). An adaptive material as claimed in any one of claims 1 to 6, wherein the sheet (2) is of fabric. An adaptive material as claimed in any one of claims 1 to 7, wherein the apertures (3) are disposed in a chequered arrangement. An adaptive material as claimed in claim 7 or claim 8, wherein the apertures (3) are formed in the sheet (2) by spaces between groups of weft threads. An adaptive material as claimed in any one of claims 1 to 9, wherein the means (5, 6) for moving the members comprises a rod (5) which runs along the edge of the sheet (2) substantially perpendicular to the members (4; 4a). An adaptive material as claimed in any one of claims 1 to 10, wherein the members (4; 4a) are moved automatically in response to a change in the surrounding conditions. An adaptive material as claimed in any one of claims 1 to 11, wherein the regions with different electromagnetic radiation absorbing and/or reflecting properties comprise regions which are coloured green, sand, brown or white. An adaptive material as claimed in any one of claims 1 to 11, wherein the regions with different electromagnetic radiation absorbing and/or reflecting properties comprise regions which are fluorescent, retro-reflective, radar and/or infra-red reflecting and/or absorbing. An adaptive material (1) comprising a sheet (2), a plurality of permeability varying members (4; 4a) retained on or within the sheet (2) such that portions of the members (4; 4a) are adjacent apertures (3) in the sheet (2), characterised by means (5, 6) for moving the members (4; 4a) relative to the sheet (2) such that different portions thereof become adjacent the apertures (3), thereby changing the overall permeability of the material (1). An adaptive material according to claim 14, wherein at least one of the portions is an air gap. An adaptive material as claimed in any one of claims 1 to 15 which is a part of a suit of clothing (6). Suit of clothing (6) comprising the adaptive material (1) of any one of claims 1 to 16. Camouflage cover comprising the adaptive material of any one of claims 1 to 16.

Inventors: BUCKLEY ROY WILLIAM, BUCKLEY, ROY WILLIAM
Applicants: JOHN HEATHCOAT & COMPANY LTD, JOHN HEATHCOAT & COMPANY LIMITED
Application year: 2000
Main classification: F41H3
IPC codes: F41H3