Invented by Kazuhisa Takagi, Yuko Takami, Yuji Koyamashita, ASAHI FR R&D Co Ltd, Asahi R&D Co Ltd
The ASAHI FR R&D Co Ltd, Asahi R&D Co Ltd invention works as followsThe dielectric material A has carbons dispersed within a silicone rubber material 1. In any of the dielectric materials A, 1), there are 150 to 300 pts.wt. Carbons are dispersed in a silicone rubber base material 1, wherein any one of the dielectric raw materials A, 1) contains 150 to 300 pts.wt. Carbons per 100 pts.wt.
Background for Dielectric raw materials, antenna device and portable phone, electromagnetic wave shielding body
Traditionally, portable phone manufacturers have demanded that they be light in weight, thin and small. They also asked for a new technology to reduce the thickness, weight and size. A request was made for an improved antenna radiation efficiency. Patent Document 1 reveals a technology that can enhance the antenna radiation efficiency of a portable telephone without compromising its compactness or lightness. Patent Documents 2 through 4, for instance, disclose technologies to enhance the antenna radiation efficiency in portable phones.
Recently however, an increased antenna radiation efficiency was requested to further reduce the thickness of mobile phones. To meet this demand, it’s necessary to create a dielectric material with an enhanced permittivity. When a dielectric material is used to increase the magnetic permeability of an electromagnetic wave shielding, it tends to make the body heavier. In recent years, the demand for portable phones with an antenna body built in has increased, as well as a tendency to reduce their size. A portable phone with an integrated antenna device has a close proximity between the antenna body and the feeding point. The conventional sheet of magnet material (electromagnetic waves controlling body) would reduce the antenna radiation efficiency if placed near the antenna body. Therefore, it was difficult to use such a sheet for an antenna built into a mobile phone.
In recent years, a growing number of apartment buildings made of ferroconcrete have been fitted with electric cooking stoves that use electromagnetic waves instead of gas cookers. In response to this trend, the development of an electromagnetic wave shielding device is required in order to protect the body from electromagnetic waves produced by an electric cooker during cooking.
DISCLOSURE of INVENTION
Problems that can be solved by invention
The present invention was made taking into consideration the above-mentioned circumstance, and one object of the invention is to provide dielectric raw materials having a high permistivity. It is also an object of the invention to provide a dielectric raw-material electromagnetic wave shielding material that can enhance antenna radiation efficiency even when disposed near the antenna body. This is especially useful for a built in antenna device in a mobile phone. It is also an object of the invention to provide a mobile phone that can be reduced in size, weight and thickness, while enhancing the antenna radiation efficiency, using an electromagnetic shielding body containing the dielectric material. It is also an object of the invention to provide a dielectric raw-material-containing electromagnetic wave shielding material that can effectively shield electromagnetic waves, such as those generated by an electric cooker.
Means to Solve the Problems
The present inventors conducted extensive and intensive investigations to achieve the above objectives. The investigations have revealed that when carbons in a silicone base material are arranged in a way to increase the mutual contact between carbons and form a carbon network, this increases the electrostatic capacitance, resulting in a dielectric material with a greater permittivity. Further intensive and extensive investigations have revealed that a dielectric material of this type can enhance the antenna radiation efficiency, even if it is placed near the antenna body. The present invention is completed based on the findings.
Accordingly to the present invention there is (1) a dielectric material with carbons dispersed within a silicone base material that contains a silicone as its main material. This can be in either of 1) to 3 described below. The carbons in the silicone rubber are not evenly distributed or they are arranged with at least some of them contacting one another.
1) A dielectric raw-material containing 150 to $300 parts by weight carbons per every 100 parts of silicone rubber.
2) A dielectric raw material that is formed by crosslinking a mixture consisting of silicone rubber in its uncrosslinked state and a noncrosslinked organic polymer, and carbons.
3) A dielectric raw material, formed by combining at least two different types of carbons, selected from flat carbon, spherical or spherical, carbon fibers with an aspect of no more than 11, carbon nanotubes, and conductive carbon.
In this case, it is preferred that the dielectric material described in (1) has at least a part of its surface with conduction pathways.
According to the present invention there is also (2) an antenna device that includes the dielectric raw materials as described in (1).” Preferably, the antenna described in (2) is an antenna built into a mobile phone.
Furthermore,” says the present invention, “there are also provided (3) a mobile phone equipped with a dielectric wave shielding material described in (1), and (4) utilizing the dielectric material described in the (1). The electromagnetic wave-shielding body described in (4) is preferably an electric cook electromagnetic wave-shielding body to shield electromagnetic waves generated by the electric cooker.
Effects Of The Invention
The dielectric material of the invention can be used to produce a dielectric material with a high permittivity that is also lightweight and flame resistant. The antenna device can also be improved in antenna radiation efficiency even when an electromagnetic wave-controlling body is located near an antenna body. This is especially useful for a built in antenna of a mobile phone. The portable phone of the invention can also be made lighter, thinner and smaller, while extending the cell life by increasing the antenna radiation efficiency. The electromagnetic wave shielding of the present invention can also be used to create an electromagnetic wave-shielding body that can shield electromagnetic waves and protect the body by shielding electromagnetic waves from electric cookers, for example.
BRIEF DESCRIPTION DES DRAWINGS
FIG. “FIG.Click here to view the patent on Google Patents.