US20070161310A1

US20070161310A1 - Methods and apparatus for infrared reflecting system

Info

Publication number: US20070161310A1
Application number: US11/329,820
Authority: US
Inventors: Steven Shope
Original assignee: U S Positioning Group LLC
Current assignee: U S Positioning Group LLC
Priority date: 2006-01-10
Filing date: 2006-01-10
Publication date: 2007-07-12

Abstract

An infrared reflecting system according to various aspects of the present invention includes an infrared reflective material and at least one layer. The infrared reflecting material is configured to deflect infrared radiation. The layers inhibit heat transfer via convection and/or conduction and/or obscure the infrared reflective material.

Description

BACKGROUND OF THE INVENTION

Three primary mechanisms facilitate heat transfer: convection, conduction, and radiation. Convection is the transfer of heat by fluid currents. As a fluid rises in temperature, it often expands and moves away from the heat source, taking energy with it. The warm air is then replaced with colder air. The human body continuously warms a thin layer of air next to the skin. If this layer is drawn away through convection, then the body feels cold. To combat heat loss through convection, humans wear clothes. Clothing attempts to minimize the amount of warm air that is lost by trapping the warm air close to the body.
Conduction is the transfer of heat through molecular movement within a material, without any motion of the material as a whole. Heat transfer between two materials occurs when the materials are in direct physical contact and have different temperatures. The rate of heat transferred is dependent upon the surface area of contact and the conductivity of the materials. Materials that pass heat easily are known as conductors, while materials that do not pass heat easily are known as insulators. Many metals have a particularly high rate of heat transfer and are thus good conductors. Plastic, wood, and cotton do not transfer heat easily, and thus are good insulators. To reduce the heat loss through conduction, clothing generally is made of materials that are good insulators.
Radiation is the transfer of heat through electromagnetic energy. This form of energy transfer does not require the presence of matter to occur. Heat transfer through radiation is from warmer to cooler objects, and occurs in all directions.
Heat transfer may also occur through a mixture of these primary mechanisms. For example, the human body may lose heat through convection, conduction, and radiation by having skin exposed to air and in contact with a conductive material. This makes the prevention of heat loss a more complicated problem.

SUMMARY OF THE INVENTION

An infrared reflecting system according to various aspects of the present invention includes an infrared reflective material and at least one layer. The infrared reflecting material is configured to reflect infrared radiation. The layers inhibit heat transfer via convection and/or conduction and/or obscure the infrared reflective material.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the following illustrative figures. In the following figures, like reference numbers refer to similar elements and steps throughout the figures.
FIG. 1 is a cross-sectional view an infrared reflective material between two layers.
FIG. 2 is a view of an infrared reflective material including woven strands.
FIG. 3 is a cross-sectional view of an infrared reflecting system including a covering.
FIG. 4 is a view of an infrared reflecting system having a flexible infrared reflecting material and layers.
Elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been rendered according to any particular sequence. For example, steps that may be performed concurrently or in different order are illustrated in the figures to help to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention is described partly in terms of functional components and various processing steps. Such functional components may be realized by any number of components configured to perform the specified functions and achieve the various results. For example, the present invention may employ various elements, infrared reflecting materials, conduction inhibitors, convection inhibitors, covering materials, and the like, which may carry out a variety of functions. In addition, the present invention may be practiced in conjunction with any number of applications and environments, and the systems described are merely exemplary applications for the invention. Further, the present invention may employ any number of conventional techniques for manufacturing, assembling, and the like.
Referring now to FIG. 1, an infrared reflecting system 100 according to various aspects of the present invention may be implemented in conjunction with an infrared reflecting material 110 between two layers 112, 114. The layers 112, 114 may be configured to face an internal environment 116 and/or an external environment 118. Generally, the infrared reflecting system 100 inhibits transfer of infrared radiation from one environment to the other. The layers 112, 114 inhibit heat transfer between the environments via conduction and convection, and the infrared reflecting material 110 inhibits heat transfer via radiation. For example, the internal environment 116 may be a human body, an animal, an object or an open space, and the external environment 118 may be a cold or warm climate, a sensor, or liquid. In various embodiments, the infrared reflecting system 100 may include only one layer 112 disposed on one side of the infrared reflecting material 110, two layers 112, 114 with the infrared reflecting material 110 disposed between the layers 112, 114, or multiple layers 112, 114, disposed one or both sides of the infrared reflecting material 110.
In the present embodiment, the infrared reflecting system 100 includes at least one layer 112, 114 on each side of the infrared reflecting material 110. The layers 112, 114 on each side of the infrared reflecting material 110 impede heat conduction and convection from the surface of the infrared reflecting material 110. The infrared reflecting system 100 may also be rigid, resilient, or flexible, such that the infrared reflecting system 100 may maintain a substantially constant shape or operate like a fabric to conform to a surface.
The infrared reflecting material 110 may comprise any suitable material that is at least partially reflective of infrared radiation (i.e., wavelengths of about 0.70 micrometers to about 1000 micrometers). In one embodiment, the infrared reflecting material 110 exhibits a high infrared reflectivity, for example approximately 0.35 or more for selected bands of infrared radiation or an average reflectivity of approximately 0.35 over the infrared band, under the conditions for which the infrared reflecting system 100 is adapted. In alternative embodiments, the infrared reflecting material 110 exhibits a higher reflectivity, for example approximately 0.50, 0.7, 0.8, or 0.9 or more for selected bands of infrared radiation, or an average reflectivity of approximately 0.50, 0.7, 0.8, or 0.9 over the infrared band. Generally, higher reflectivity in the infrared band improves the performance of the infrared reflecting system 100. In the present embodiment, the infrared reflecting material 110 comprises a material that reflects infrared radiation and exhibits low absorptivity of infrared radiation. For example, infrared reflecting material 110 may comprise one or more of several metals, such as copper, aluminum, gold, silver, beryllium, chromium, molybdenum, nickel, platinum, rhodium, tungsten, related alloys, and the like, that exhibit relatively high reflectivity of infrared radiation. Alternatively, the infrared reflecting material 110 may comprise a material having a high dielectric constant in the frequency range of interest, such as plastics, nylons, and/or rayons, treated with a high infrared reflectivity material and/or a high conductivity material. The infrared reflecting material 110 may be impregnated or otherwise treated with additional materials to create the infrared reflecting material 110 having any appropriate characteristics.
The infrared reflective material 110 may be configured in any suitable manner. In various embodiments, the infrared reflective material 110 may comprise a rigid and/or a flexible material. For example, the infrared reflecting material 110 may include a foil, film, strands, or other material including an infrared reflecting material, or foil, film, strands, or other material with a coating of infrared reflecting material. The infrared reflecting material 110 may be configured in any suitable manner, such as having any suitable thickness, material, reflectivity, flexibility, strength, and the like. The infrared reflecting material is suitably thick enough to effectively reflect infrared radiation.
For example, referring to FIG. 2, one embodiment of the infrared reflecting material 110 may comprise multiple woven strands 200. The strands 200 may comprise any appropriate material, such as threads or wire, and may be solid, hollow, parsed, twisted, or otherwise configured. In the present embodiment, the strands 200 are woven together in any suitable pattern to form a flexible fabric, allowing the fabric to conform to a surface or shape. Where the strands 200 have a coating, the coating may be applied before or after weaving. In one embodiment, the infrared reflecting material 110 includes a conductive fabric from Sauquot Industries comprising fiber strands coated with silver, gold, or other infrared reflective material, and woven to form a fabric. The strands may be configured, however, in any suitable manner, such as any suitable thickness, weave density, type of weave, material, reflectivity, flexibility, strength, coating thickness, coating material, coating reflectivity, and the like.
The infrared reflecting material 110 may also be adapted according to the particular application. For example, the infrared reflecting material 110 may be durable and resistant to corrosion, and may comprise any suitable dimensions and thickness. Further, the infrared reflecting material 110 may be configured and/or shaped for any suitable purpose, such as retaining heat, shielding from heat, shielding from sensors, or communication. For example, the infrared reflecting material 110 may comprise a large sheet, tarp, or other cover that may be interposed between an infrared sensor and an item to be hidden, such as a person or equipment. In another embodiment, the infrared reflecting material 110 may form letters or other symbols. The letters, symbols, or the like may be visible via an infrared sensor, but would be obscured by the layers 112, 114 that may transmit infrared radiation but opaque to visible light. The letters and/or symbols may be used for any suitable purpose, such as to identify a wearer or designate a particular area or item of interest. In another embodiment, the infrared reflecting material 110 may be configured for alternative functions, such as to form an antenna.
The layers 112,114 may inhibit heat transfer via convection and/or conduction, and may conceal and/or protect the infrared reflecting material 110. The layers 112, 114 may be comprise any suitable material, and may be configured in any suitable manner, such as rigid structures or flexible sheets having any appropriate dimensions or thicknesses. In one embodiment, at least one of the layers 112, 114 may comprise a vacuum. In another embodiment, referring to FIG. 3, the layers 112, 114 may comprise insulation 316 and covering materials 312, 314. The insulation 316 inhibits heat transfer via conduction and/or convection. The insulation 316 may comprise any suitable material for inhibiting convection and/or conduction, such as a conventional thermal insulator, for example, wool, silk, cotton, leather, natural fibers, synthetic fibers, and other appropriate materials.
The covering materials 312, 314 lay over the insulation 316. The covering materials 312, 314 may serve any suitable purpose, such as to protect the insulation 316 and/or infrared reflecting material 110, add comfort, provide an interface for mounting or connecting to another system, or other suitable purpose. For example, in one embodiment, one or both of the covering materials 312, 314 comprises a waterproof covering for repelling moisture. The covering materials 312, 314 may also substantially block or transmit visible light. Separate covering materials 312, 314 and insulation 316 may be beneficial where the insulation 316 is poorly suited for exposure. For example, in a household insulation system, the insulation 316 may comprise fiberglass, and the covering material 312 drywall. Another example is a down comforter, where the insulation 316 comprises down feathers and the covering 312 is a cotton, nylon or silk material.
The infrared reflecting system 100 may be configured and/or adapted for any suitable application or environment. For example, the layers 112, 114 and the infrared reflecting material 110 may be permeable to water vapor but impermeable to liquid water, such as by forming small perforations in the layers 112, 114 and the infrared reflecting material 110. Thus, the infrared reflecting system 100 provides a “breathable” system that allows humidity to escape, but repels the elements, like rain and snow, while inhibiting the heat loss. In other applications, such as for a dry suit or a tarp, the infrared reflecting system 100 may include substantially waterproof materials or be treated with a waterproofing agent. Alternatively, the infrared reflecting system 100 may be permeable to water but configured to retain heat, for example using larger holes in the layers 112, 114 and the infrared reflecting material 110, for use in various applications such as a wetsuit.
FIG. 4 illustrates an infrared reflecting system where the infrared reflecting material 110 and the layers 112, 114 are flexible, for example to conform to a surface. The infrared reflecting system 100 may be configured to conform to any kind of garment, blanket, survival enclosure, tarp, or other cover or protection. For example, the infrared reflecting system 100 may be incorporated into cold weather garments, footwear, and headgear, as well as environmental protective gear, such as sleeping bags, tents and shelters, ground pads, and survival enclosures. The flexible infrared reflecting system 100 may also be incorporated into diving suits, including wet suits and dry suits, blankets, bedding, tarps, medical coverings, awnings, and umbrellas. For infrared shielding or reflection, the flexible infrared reflecting system 100 may also be incorporated into military items as well, such as camouflage clothing, equipment, and material, military decoy material, and infrared ground marking targets. In alternative embodiment, the infrared reflecting system 100 is rigid, for example for household insulation, packaging materials, storage containers, pool covers, and/or window blinds. Furthermore, the system may be used to shield a person, object, or area from sensors, such as for a privacy garment that inhibits millimeter wave radar or infrared sensors from scanning individuals wearing the garment.
The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, conventional materials, configurations, coatings, and other functional aspects of the systems may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationships or physical connections may be present in a practical system.
The present invention has been described above with reference to a preferred embodiment. However, changes and modifications may be made to the preferred embodiment without departing from the scope of the present invention. These and other changes or modifications are intended to be included within the scope of the present invention, as expressed in the following claims.

Claims

1. An infrared reflecting system comprising:

an infrared reflecting material with high infrared reflectivity; and

an inner layer and an outer layer, wherein:

the layers inhibit convection and thermal conduction; and

the infrared reflecting material is disposed between the layers.

2. An infrared reflecting system according to claim 1, wherein the infrared reflecting material comprises a plurality of strands.

3. An infrared reflecting system according to claim 2, wherein the infrared reflecting material comprises a woven material.

4. An infrared reflecting system according to claim 2, wherein the strands comprise at least one of a metal, a metal coating, and a material having a high dielectric constant.

5. An infrared reflecting system according to claim 1, wherein at least one layer further comprises an insulation and a covering.

6. An infrared reflecting system according to claim 1, wherein the infrared reflecting material further comprises a corrosion resistant material.

7. An infrared reflecting system according to claim 1, wherein the infrared reflecting material and the layers are flexible.

8. An infrared reflecting system according to claim 1, wherein the layers and infrared reflecting material are permeable to at least one of water and water vapor.

9. An infrared reflecting system according to claim 1, wherein the infrared reflecting material contains at least one of symbols and letters.

10. A method for reflecting infrared rays comprising:

providing an infrared reflecting material; and

placing the infrared reflecting material between a first layer of convection inhibiting and thermal conduction inhibiting material and a second layer of convection inhibiting and thermal conduction inhibiting material.

11. A method for reflecting infrared rays according to claim 10, wherein the material substantially conforms to a surface.

12. A method for reflecting infrared rays according to claim 10, wherein the system comprises at least a portion of at least one of a survival blanket and a survival enclosure.

13. An infrared reflecting system according to claim 10, wherein the layers and infrared reflecting material are permeable to at least one of water and water vapor.

14. An infrared reflecting system comprising:

a flexible infrared reflecting fabric exhibiting high infrared reflectivity; and

an inner layer and an outer layer, wherein the layers inhibit convection and thermal conduction;

and the infrared reflecting material is between the layers.