Patent Application
20110227799
1. Field of the Invention
The present invention relates to an antenna for use in RF-ID (Radio Frequency Identification) and NFC (Near Field Communication), as well as to a portable terminal using the same.
2. Description of the Related Art
In recent years, a loop antenna has frequently been used in a portable terminal, like a portable phone and a smart phone, in order to read information from a non-contact IC card and an IC tag and exchange information with a reader/writer.
In general, the loop antenna is smaller than the non-contact IC card, and a magnetic field capture area (a communicable area) is narrow. For these reasons, when the loop antenna reads information from; for instance, a non-contact IC card, difficulty is often encountered in reading information.
Accordingly, in order to expand the communicable area, a combination of the loop antenna with a metallic line is available (see; for instance, JP-2008-28506A).
However, since the communicable area is expanded by use of the metallic line in the related art structure, an air field where the metallic area is absent exists in the vicinity of the expanded area.
For this reason, if a transmission magnetic field originating from the non-contact IC card enters the air field, dielectric electromotive force originating from a magnetic flux from the IC card hardly develops in the loop antenna. As a consequence, even when a communication area is expanded, there is a potential of the loop antenna being unable to establish a communication with the IC card in the air field.
Accordingly, in light of the foregoing problem, the present invention aims at providing an antenna that exhibits superior communication performance win a communicable area while expanding the communicable area as well as a portable terminal using the antenna.
In order to solve the problem, the present invention provides an antenna comprising a loop antenna having an aperture; a metallic body that is electrically insulated from the loop antenna and that is placed on one side where the aperture of the loop antenna is provided; and a notch that is smaller than an outer shape of the loop antenna and that is coupled with a periphery of the metallic body, wherein the loop antenna is placed on the metallic body so as to cover the notch.
The present invention makes it possible to provide an antenna that exhibits superior communication performance within a communicable area because an air field in the communicable area is reduced while expanding the communicable area and provide a portable terminal using the antenna.
Another objective of the present invention is to cause an electric current oriented in a direction to cancel an electric current flowing through a loop antenna to flow through the notch, whereby an electric current oriented in the same direction as that of the electric current flowing through the loop antenna flows through the entire metallic body, so that the antenna pattern can be apparently made greater.
Still another objective of the present invention is to make it easy to generate an eddy current flowing through a metallic body, so that more superior communication performance is exhibited within a communicable area.
Yet another objective of the present invention is to let a loop antenna oppose a metallic body without fail, whereby much superior communication performance is exhibited within a communicable area.
Yet another objective of the present invention is to let a loop antenna oppose a metallic body without fail in the greatest area, so that extremely superior communication performance is exhibited within a communicable area.
An antenna of the present invention includes a loop antenna having an aperture and a metallic body that is electrically insulated from the loop antenna and that is provided on one side where the aperture of the loop antenna is provided. A notch that is smaller than an outer shape of the loop antenna and that is coupled with a periphery of the metallic body is provided on the metallic body. The loop antenna is placed on the metallic body so as to cover the notch.
It thereby becomes possible to reduce an air field within a communicable area while the communicable area is being expanded, so that an antenna exhibiting superior communication performance within a communicable area can be provided.
Further, the notch is substantially identical in size with the aperture of the loop antenna, whereby the antenna can be coupled with the metallic body with superior efficiency, so that electric power induced in the metallic body by an external magnetic field can be transmitted to the antenna with superior efficiency.
The antenna is provided within enclosures, and the metallic body is provided on a back side of one of the enclosures, whereby it is possible to provide a portable terminal that exhibits superior communication performance within a communicable area while the communicable area is being expanded by utilization of the enclosures.
Further, the antenna is provided within the enclosures, and a circuit board provided within the enclosures is used as a metallic body. It thereby becomes possible to provide a portable terminal that exhibits superior communication performance within a communicable area while the communicable area is being expanded by utilization of the circuit board of the portable terminal.
Embodiments of the present invention are hereunder described by reference to the drawings.
The antenna 1 shown in
In order to lessen influence generated when metal is placed on the antenna, a magnetic sheet 4 is placed on the antenna pattern 3.
The antenna pattern 3 is connected to an input-output terminal of a matching circuit and an input-output terminal of an IC by means of input-output terminals 5 and 6.
A metallic body 7 is provided with a notch 8 that is formed so as to connect with a periphery of the metallic body 7 and that assumes a rectangular shape matching the shape of the antenna. The metallic body 7 is formed into the shape of the letter C by means of the notch 8.
Specifically, the notch 8 is not formed so as to make a hole in the metallic body 7 but assumes a shape cut out of the periphery of the metallic body 7.
The antenna board 2 and the antenna pattern 3 are positioned, while substantially adjoining the metallic body 7, so as to cover the notch 8 of the metallic body 7, and the metallic body 7, the antenna board 2, the antenna pattern 3, and the magnetic sheet 4 are stacked in sequence.
Detailed descriptions are provided to the shape of the antenna pattern 3 and the shape of the notch 8 by reference primarily to
As is obvious from the drawings, the notch 8 is smaller than an outer shape of the antenna pattern 3 (the outermost loop of the antenna pattern 3), and the notch is also formed so as to extend along an aperture (the innermost loop of the antenna pattern 3) of the antenna pattern 3.
Specifically, the notch 8 is made substantially equal in size to the aperture of the antenna pattern 3.
The aperture of the antenna pattern 3 is arranged so as to match the notch 8. As shown in
As shown in
The configuration mentioned above makes it possible to efficiently utilize an electric current developing in the metallic body 7, which will be described later.
In the embodiment, the notch 8 is placed so as to situate at the center of the side where the notch is to be formed.
A configuration of the antenna 1 is hereunder described.
First, the antenna board 2 is described. The antenna board 2 is a base board on which electronic members, like the antenna pattern 3, the input-output terminals 5 and 6, and others, are to be mounted. In the embodiment, the essential requirement for the base board is a substrate that exhibits an insulation property. The base board can be formed from; for instance, polyimide, PET, a glass epoxy substrate, and the like.
The antenna pattern 3 is now described. The antenna pattern 3 is formed in a spiral shape. A spiral structure is a spiral shape having an aperture in its center. The spiral structure can assume either a circular shape, a substantial rectangular shape, or a polygonal shape typified by a triangular shape and a square shape. Moreover, the antenna pattern 3 may also be placed in one plane or piled. By adoption of a spiral structure, a magnetic field developing from a reader/writer is caused to effect inter-linkage with the aperture, to thus induce electric power, and it becomes possible to transmit an electric signal to a matching circuit connected to the input-output terminals 5, 6 and an IC chip and to establish communication with the reader/writer. Any material is used as a material for the pattern, so long as the material exhibits electrical conductivity. The material is selected as appropriate from a conductive metallic wire, a metallic plate material, a metallic foil material, and a metallic sleeve material, like gold, silver, copper, aluminum, and nickel. The pattern can be formed from a metallic wire, a metallic foil, a conductive paste, transfer plating, sputtering, deposition, or screen printing.
The magnetic sheet 4 is now described. The magnetic sheet 4 is placed on the antenna pattern 3 and may assume any of a circular shape, a substantially rectangular shape, or a polygonal shape typified by a triangular shape or a square shape. The magnetic sheet 4 is intended for lessening influence which arises when the metallic body is placed on the magnetic sheet 4. It is desirable that the magnetic sheet 4 shall completely cover the antenna pattern 3. So long as the magnetic sheet covers the antenna pattern 3, the magnetic sheet may be larger than the antenna pattern 3. For instance, the magnetic sheet may also be equal in size to the metallic body 7.
Further, either an insulating magnetic material like ferrite or a conductive magnetic material like an electromagnetic steel plate can also be employed as a material for the magnetic body.
The input-output terminals 5 and 6 are now described. The input-output terminals 5 and 6 are electrically connected to the antenna pattern 3. Any material is available, so long as the material exhibits conductivity. The material can be selected as appropriate from a conductive metallic wire, a metallic plate material, a metallic foil material, and a metallic sleeve material, like gold, silver, copper, aluminum, and nickel. The input-output terminals can be formed from a metallic wire, a metallic foil, a conductive paste, transfer plating, sputtering, deposition, or screen printing. The input-output terminals 5 and 6 are electrically connected to a matching circuit and an IC chip. There can be selected a commonly utilized connection technique, such as pin connection, spring connection, soldering, connector connection, and the like.
Any material is used as a material for the input-output terminals, so long as the material exhibits electrical conductivity. The material is selected as appropriate from a conductive metallic foil material and a metallic plate material, like gold, silver, copper, aluminum, and nickel. The input-output terminals can be formed from a metallic foil, a conductive paste, transfer plating, sputtering, deposition, or screen printing.
A concept of operation of the antenna of the present invention is now described by reference to
A one-turn search coil measuring 72 mm×42 mm is placed above the antenna 1, and both ends of the search coil are connected to observation terminals of an oscilloscope, thereby carrying out observations at a port impedance of 1 MΩ. The magnetic field developed from the antenna 1 performs cross linkage with respect to the search coil, whereupon an induced voltage occurs at both ends of the search coil. The induced voltage is observed by means of the oscilloscope. The search coil is disposed in such a way that a center of the metallic body 7 of the antenna 1 faces up to a center of the search coil.
When the metallic body 7 is not used, the center of the antenna pattern 3 is arranged so as to face up to the center of the search coil. A horizontal axis shown in
Although the metallic body 7 does not need to be attached to the enclosure 24, the characteristic of the antenna will be deteriorated when metallic components mounted on the metallic body 7 and metallic components mounted on the board 21 approach each other. Therefore, it is desirable to keep the metallic components mounted on the metallic body as far away as possible from the metallic components mounted on the board 21.
The enclosure 24 and the metallic body 7 can also be integrated together. Any material may be employed for the enclosure 24 in the case, so long as the material exhibits conductivity in the same manner as does the metallic body 7. The material is selected as appropriate from a conductive metallic plate material, and a conductive metallic foil material, like gold, silver, copper, aluminum, and nickel. The enclosure can be formed from a metallic foil, a conductive paste, transfer plating, sputtering, deposition, or screen printing.
The board 21 can also be used in place of the metallic body 7. In such a case, the antenna is disposed on the other side of the board 21 where the liquid crystal panel is not disposed. From the structural viewpoint, the magnetic sheet 4 and the antenna pattern 3 are provided on the underside of the board 21 in sequence from the board.
Moreover, in the present embodiment, the metallic body 7 is formed from a metallic foil, or the like. Therefore, for instance, a notch is formed in the metallic body 7 in accordance with a layout of components in a portable terminal into which the antenna is to be incorporated, such as a camera, so that the metallic body can be arranged so as to avoid the layout of the components.
A foldable material, such as a metallic foil, is utilized for the metallic body 7 as mentioned above, or the metallic body is formed directly on a curved surface of an enclosure by means of sputtering, or the like. Thus, the metallic body 7 can be placed along the curved surface of the enclosure. Thus, as compared with a related art antenna that cannot be disposed on a curved surface, the antenna can be freely designed.
In the antenna 1 shown in
A concept of operation of the antenna of the present invention is now described by reference to
In
As mentioned above, the antenna of the present invention includes the followings; namely, a loop antenna having an aperture, a metallic body that opposes the loop antenna and that is electrically insulated from the loop antenna; and a notch that is provided in the metallic body and that is coupled with the periphery of the metallic body. At least a portion of the loop antenna opposes the metallic body, and at least a portion of the notch is covered with the aperture. An air field in a communicable area is reduced while the communicable area is being expanded. Therefore, it is possible to provide an antenna that exhibits superior communication performance within the communicable area.
As a result of the metallic body being disposed on the side where the aperture of the loop antenna exits, an eddy current flowing through the metallic body becomes likely to develop, and much superior communication performance can be exhibited within the communicable area.
An outer shape of the loop antenna is smaller than the metallic body, and the notch is smaller than the outer shape of the loop antenna, so that the loop antenna thoroughly faces the metallic body. Hence, much superior communication performance can be exhibited within the communicable area.
The aperture of the loop antenna is placed on the metallic body so as to cover the entirety of the notch. As a result, the loop antenna thoroughly opposes the metallic body within the greatest area, and hence highly superior communication performance can be exhibited within the communicable area.
Since the notch is substantially equal in size with the aperture of the loop antenna, the loop antenna thoroughly opposes the metallic body, so that the magnetic field passing through the aperture is not blocked by the metallic body. Accordingly, the loop antenna thoroughly opposes the metallic body within the greatest area and hence highly superior communication performance can be exhibited within the communicable area.
The entirety of an end that is an end of the metallic body and that makes up the notch opposes the loop antenna. As a result, the loop antenna opposes the metallic body without fail in the greatest area, and hence very excellent communication performance can be exhibited within the communicable area.
The metallic body includes the notch covered with the aperture of the loop antenna, an opposite direction current generation block that opposes the loop antenna, and a non-opposing block that does not opposes the antenna. As a result, the communicable area can be expanded without fail. Since the air field in the communicable area is reduced, there can be provided an antenna that efficiently exhibits superior communication performance within the communicable area.
Further, an electric current flowing through the opposite direction current generation block is opposite in direction to an electric current flowing through the loop antenna. An electric current flowing through the non-opposing block is identical in direction with the electric current flowing through the loop antenna. The communicable area is thereby expanded without fail. Moreover, since the air field in the communicable area is reduced, there can be provided an antenna that efficiently exhibits superior communication performance within the communicable area.
A magnetic field caused by the electric current flowing through the opposite direction current generation block is opposite in direction to a magnetic field caused by the electric current flowing through the loop antenna. A magnetic field caused by the electric current flowing through the non-opposing block is identical in direction to the magnetic field caused by the electric current flowing through the loop antenna. The communicable area can thereby be expanded reliably. Further, the air field in the communicable area is reduced, and hence there can be provided an electronic device that efficiently exhibits superior communication performance within the communicable area.
The entire aperture of the loop antenna is situated within the notch, whereby a magnetic field passing through the aperture is not blocked by the metallic body. Accordingly, the loop antenna thoroughly opposes the metallic body within the largest area, and hence much superior communication performance can be exhibited within the communicable area.
The antenna of the present invention has the followings; namely, a loop antenna having an aperture, a metallic body that is electrically insulated from the loop antenna and that is placed on a side where the aperture of the loop antenna is provided; and a notch that is smaller than the outer shape of the loop antenna, that is provided in the metallic body, and that is coupled with a periphery of the metallic body. The loop antenna is placed on the metallic body so as to cover the notch. The air field within the communicable area is thereby reduced while the communicable area is being expanded, and hence there can be provided an antenna that exhibits superior communication performance within a communicable area.
Further, as a result of the antenna being disposed in the enclosures and the metallic body being provided on the back side of the enclosure, the air field within the communicable area is reduced while the communicable area is being expanded. Hence, there can be provided an antenna that exhibits superior communication performance within the communicable area.
The antenna is disposed within the enclosures, and a circuit board disposed within the enclosures is used as a metallic body. The air field within the communicable area is thereby reduced while the communicable area is being expanded, and hence there can be provided an electronic device that exhibits superior communication performance within the communicable area. Further, further miniaturization of the antenna can be pursued.
The antenna of the present invention and the portable terminal using the same exhibit superior communication performance within a communicable area while expanding the communicable area and hence are useful for an electronic device, like a portable phone.
This application claims the benefit of Japanese Patent application No. 2010-060617 filed on Mar. 17, 2010, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2010-060617 | Mar 2010 | JP | national |
