GB2320902A

GB2320902A - Material with thermal properties

Info

Publication number: GB2320902A
Application number: GB9700019A
Authority: GB
Inventors: Stuart Collier
Original assignee: Colebrand Ltd
Current assignee: Colebrand Ltd
Priority date: 1997-01-02
Filing date: 1997-01-02
Publication date: 1998-07-08
Anticipated expiration: 2017-01-02
Also published as: GB9700019D0; GB2320902B

Abstract

A material with thermal properties comprises a metal film supported on a carrier sheet, the metal film being coated with a pigmented polymer. Such material can be used as a background for a display panel, a symbol being mounted in front of the background material with means for changing the temperature of the symbol in relation to the background material.

Description

MATERIAL WITH THERMAL PROPERTIES This invention relates to a material with thermal properties and also covers a display panel using such material.

A panel displaying a symbol benefits from the provision of a background to the symbol in order that the symbol can be recognised in a variety of situations. When it is desired not to use visible radiation for viewing the display, it is sometimes convenient to use wavelengths in the infrared region and to make the symbol more recognisable by changing its temperature in relation to the background, for example by means of a heating pad. The background material should clearly be thermally insulated from the heated symbol and its heating pad, but our researches have revealed a class of materials which provide much improved recognition of symbols when they are used as the background material. Such materials are known as thermal recognition materials and comprise a thin metal film, vaporised and vacuum deposited onto a carrier sheet preferably of plastics. The metal film is itself coated with a thin, pigmented, polymeric solution.

Such materials have utility in many applications in which a heat sink is required.

An example of the invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a plan of a display panel and Fig. 2 is a diagrammatic side elevation of the panel of Fig. 1 affixed to a structure.

A rectangular display panel 11 has a substrate film of polyester of from 8 to 20, preferably 12 micron thickness with an aluminium film of from 15 to 30 microns, preferably 20 microns thickness vapour deposited thereon, with a substantially uniform coating of pigmented vinyl copolymer solution 12 at a thickness of from 2 to 5 microns, preferably 3 microns. Mounted on the front surface of the substrate is a V-shaped symbol 13 of stainless steel provided with a heating pad embedded in polyurethane foam insulation. The substrate film is mounted on a secondary plastics film, typically low density polyethylene at a thickness of from 30 to 80 microns, preferably 50 microns using permanent adhesive (polyester bonded to polyethylene) at a thickness of from 15 to 30 microns, preferably 20 microns. This polyethylene film then has a layer of pressure sensitive adhesive applied to it at a thickness of 15 to 30 microns, preferably 20 microns, covered by a Kraft release paper to construct a self-adhesive tape and the tape can be stuck to a suitable backing board.

The panel can be mounted in a variety of ways and one suitable way is to provide a hinge 21 along the top edge of the panel fixed to a vertical surface 22 and to provide a hinged to bracket 22 from a lower point on the vertical surface against which the lower back edge of the substrate bears so that the panel is inclined to the vertical by a suitable angle in the range of 10 to 450, preferably 300, as shown in Fig. 2. In Fig. 2, the vertical surface 22 is the front surface of a stowage bin 24 on the turret of a tank. The panel can be detached from the front surface and stowed within the bin when not in use but can easily be mounted on the front surface of the stowage bin by the hinge and bracket arrangement shown in Fig. 2. The inclination of the panel can be adjusted in order to make the sign most visible from the direction from which it is expected to be recognised. If the tank is likely to be traversing rough ground, then the panel can be provided with anchoring means, such as elastic straps to hold it in the desired position during motion of the tank.

In this embodiment, the symbol is heated from a 12volt battery and achieves a temperature of approximately 40 centigrade and this temperature difference in relation to the background of thermal recognition material provides sufficient contrast for easy recognition. The special properties of the thermal recognition material enable the contrast to be maintained in hot conditions when the remainder of the tank is at temperatures approaching 40 C.

An unheated symbol on a background of thermal recognition material can be recognised by suitable sensors in most conditions but in very moist conditions, such as mist or rain, the outer coating of moisture on the material camouflages the material behind it and presents much the same radiation as that emanating from the moisture-covered symbol itself. By heating the symbol, moisture is driven off and the difference between the heated symbol and the thermal recognition material can be recognised, even in such moist conditions.

Other materials suitable for the substrate include polyethylene, polypropylene, polycarbonate at thicknesses between 5 microns and 25 microns. Other metals for the vapour-deposited film include gold, silver, copper and nickel at thicknesses of 5 microns to 50 microns. The pigments of the polymeric coating can be organic and/or inorganic.

Other suitable polymeric coating may be acrylic, polyurethane, chlorinated rubber, epoxy, fluorocarbons, polyethylene and silicones at thicknesses of 2 microns to 10 microns.

Claims

1. A thermal recognition material comprising a metal film supported on a carrier sheet, the metal film being coated with a pigmented polymer.

2. A material as claimed in claim 1 wherein the carrier sheet is a plastics sheet.

3. A material as claimed in claim 2 wherein the carrier sheet is of polyester.

4. A material as claimed in any one of the preceding claims wherein the metal film comprises aluminium.

5. A material as claimed in any one of the preceding claims wherein the coating is applied as a vinyl co-polymer solution.

6. Thermal recognition material substantially as herein before described with reference to the accompanying drawings.

7. A display panel comprising a background of thermal recognition material as claimed in any one of the preceding claims and a symbol mounted in front of said background material together with means for changing the temperature of said symbol in relation to said background material.

8. A display panel as claimed in claim 7 wherein said background comprises said thermal recognition material mounted on a plastics film.

9. A display panel as claimed in claim 8 wherein said plastics film is provided with an adhesive layer for attaching the display panel to a suitable structure.