DESCRIPTION

FABRIC THAT HAS THE PROPERTY OF SHIELDING ELECTROMAGNETIC FIELDS

Subject of the Invention

This invention is about a fabric that has the property of shielding electromagnetic waves created by devices like cellular phones, televisions, computers, radios.

State of Prior Art

With developments in technology, devices creating electromagnetic waves have become part of our daily lives. Cellular phones, televisions, satellite receivers, satellite transmitters, imaging and sound transmission devices, computers, radios and all kinds of signal receiving and transmitting devices cause electromagnetic pollution.

In the electromagnetic spectrum, the electromagnetic field that is in Radio Frequency (RF) band in the range between 3 kHz and 300 GHz is created by many devices like phones and televisions which we use daily. Thus, today there is virtually no environment which is free of electromagnetic field.

Electromagnetic fields can harm living things, electronic devices, systems as well as the environment, through public transportation vehicles. For example, the distortion of an image displayed on a computer screen by the usage of a cellular phone is a proof of this harmful effect of electromagnetic fields.

The effect of electromagnetic waves on living things emerges as increase in body temperature. When humans are subjected to electromagnetic waves in the RF region for long periods of time they experience headaches, burning in the eyes and fatigue. The effect of electromagnetic waves on human health varies with the level of the energy and the exposure time to the energy.

In the state of art, protection from harmful effects of electromagnetic waves scientifically is achieved by shielding. The environment or matter that is to be protected is electromagnetically isolated. Materials like silver, copper, steel that have high conductivity are used for electromagnetic shielding.

Electromagnetic shielding is frequently used in high sensitivity cables, electronic circuit and systems today. Shielding is achieved by overlaying or covering the regions which are desired to be protected with highly conductive metals. Generally, the metal in the form of layer is used to overlay or cover the surface of the object that is to be protected. Electromagnetic Shielding is achieved by adding metal plates, metal reinforced composite fibers, or metal fragments to various material structures.

Nevertheless, these kinds of products are expensive products that are used in the industry and which are not suitable for personal or home usage. Products providing electromagnetic shielding have been developed in recent years and these products have especially been tried to be modified for personal use.

One application which is in the state of art is manufacturing of fabric that has the property of weakening electromagnetic fields. Fabrics manufactured by using the current methods are produced by adding thin layers of metal to a layered fabric structure.

Metal plates added to the fabric as a layer provide the fabric with the property of low electromagnetic wave permeability but they also lead to the stiffening of the fabric and increasing its weight. These fabrics create problems in the areas they are used and also they are not suitable to personal use.

Aimed at removing the disadvantages of stiff fabrics, Japanese patents published with numbers 1996176962 and

1998292252 have created a layer that hinders passage of the waves by using flexible conductive fibers. However, the usage of these fabrics that are 100% metal reinforced is limited due to their stiffness and they can cause allergic reactions when they are in contact with the human body. The materials which are the subject of the aforementioned inventions can not be preferred due to their high price and limited use.

Decreasing electromagnetic permeability has been the subject of many inventions; yet, none of the applications included a fabric that has high shielding property and a soft touching and also has the desired properties.

With this invention, a fabric which has low electromagnetic permeability, which can have any patterns and the necessary softness suitable for usage in any field, and which can be manufactured by knitting or weaving is obtained.

Detailed Description of the Invention

The subject of the invention is related to a fabric which weakens the electromagnetic field in the interval between AF and SHF (0-48 GHz) ; which has a net structure that is formed by highly conductive metal filaments (1) like copper, silver, steel, nickel, carbon; and that can be obtained by either knitting or weaving method.

Usage of filaments (1) made of silver, copper, steel, carbon or alloyed metal filaments in knitted or woven fabric such that they will form a net structure provides the fabric with the electromagnetic field shielding property.

Metal filaments (1) are tied in a continuum, such that they will not lose contact with each other, to form a net structure in the base of the fabric. Through the usage of this structure, which is formed in the back faces and is independent of the pattern on the fabric, another type of filament (2) that can create the desired soft touch effect in the front face can be used.

The fabric that has the electromagnetic field shielding property is obtained by knitting or weaving methods. The fabric manufactured through either of the two methods, weakens electromagnetic fields by the reflection and absorption mechanisms of the net structure formed by highly conductive filaments (1) .

The net structure formed in the base of the fabric by weaving is obtained by making 90° angles between the metal weft filaments and warp filaments. Before the woven fabric is

manufactured, the warp in which metal filaments are pulled with a pattern is prepared. The metal filament to be used is put next to another during warp pulling and the pattern is thus formed. The metal filament is laid on this warp as the weft to form the pattern. For example, an ordered series is formed by placing three polyester filaments next to three metal filaments. The presence of the same ordered series structure in the warp creates the chequered look on the fabric.

Owing to the net structure formed by the metal filaments in the base layer the fabric can be given the desired patterns. Since the electromagnetic field shielding property would increase with decreasing the distance between the rectangles formed, the electromagnetic field weakening property is also increased.

The woven fabric is fundamentally made up of two sections: the base and the front face. Alternatively, an additional layer can be formed between the front face and the base of the fabric by using inlay filaments (b) . Additional properties can be added to the fabric by using inlay filaments (b) . The three layered knit structure of the fabric is shown in Figure 2.

For example, kanecaron and outlast filaments (b) that can be inlaid in the metal filament (1) net structure or the front face can provide the fabric with the property of delayed flammability and thermal insulation, in addition to further decreasing its electromagnetic field permeability.

For example, usage of silver coated filaments in the net structure of base provides the electromagnetic field

weakening property while usage of another filament (2) in the front face provides the fabric with the desired properties and soft touching.

In figure 1, the net structure formed in the base was formed with two layers of filaments and the metal filaments (1) were knitted without letting them lose contact with each other. Forming the net structure in the base with one layer of filaments (1) is possible. Conductivity can be achieved in the net structure, keeping the filaments (1) in touch with each other, when one layer of filaments is knitted as well.

Instead of knitting the base of the fabric with metal coated or alloyed filaments, electromagnetic field shielding property can also be provided by forming a base with applying a mixture that includes metal particles of 60-80 microns made of silver, copper, steel, carbon, which have high conductance coefficient to the back face of the fabric.

Effectiveness of the electromagnetic shielding property is increased with the single layered base in the net structure by means of the continuous structure formed. Thus, the net structure obtained in the base by one layer of metal filaments (1) provides economy in terms of cost of filament.

In this invention, even the net structure that is formed in the base with just one layer of metal filaments (1) allows for obtaining a fabric that has electromagnetic field shielding property economically and practically.

Since the filaments (1) that make up this fabric having electromagnetic shielding property is in net structure a

suitable structure that allows for obtaining fabric having different degrees of softness and patterns can be created.

Since the electromagnetic shielding property of the fabric can be altered based on the type of metal filament (1) used, the net structure, and the manufacturing method (weaving or knitting) , the fabric can be manufactured to have the appropriate shielding effectiveness and appropriate fabric properties depending on usage.

The fabric having electromagnetic field shielding property incorporates all of the fabric properties of the state of the art since it has layers (front face, inlay layer and the base) connected to each other by the net cage structure of metal filaments (1) .

Explanation of Figures

Explanations of the figures pertaining to the invention are as follows:

Figure 1 : Knitted base net structure with two filaments Figure 2 : Knitted base fabric structure with three layers

References

1. Metal filament

2. Other filament a. Base filament b. Inlay filament

C. Front face filament d. Second base filament e . Second front face filament