The present disclosure relates to antenna components and, in particular, to an antenna component used in a short-range wireless communication system.
One known example antenna component is a transmission antenna coil described in Patent Document 1. The transmission antenna coil includes a magnetic core and leads. The magnetic core has a stick shape extending along a predetermined direction. A first winding portion and a second winding portion are formed by winding the leads. The first winding portion and second winding portion are spaced apart from each other in the predetermined direction. In this transmission antenna coil, a magnetic flux leaks from between the first winding portion and second winding portion, a rise in self-inductance is reduced, a Q factor decreases. This results in a wide resonance range and improved broadness in the transmission antenna coil.
There is a desire to achieve a larger output in the above-described transmission antenna coil in Patent Document 1.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-175965.
Accordingly, it is an object of the present disclosure to provide an antenna component from which a large output is obtainable.
An antenna component is disclosed that includes a magnetic core and a coil antenna including a first coil portion to an nth coil portion (n being an integer more than two) wound around the magnetic core. The first coil portion to the nth coil portion are electrically connected in series and are disposed such that they are spaced apart from each other and arranged in the order from the first to nth coil portions. The number of turns of each of the second coil portion to the (n−1)th coil portion is smaller than the number of turns of each of the first coil portion and the nth coil portion.
In the above-described antenna component, preferably, the magnetic core may have a stick shape extending along a predetermined direction, and the first coil portion to the nth coil portion may be disposed such that they are spaced apart from each other in the predetermined direction and arranged in the order from the first to the nth coil portions.
In the above-described antenna component, preferably, the first coil portion to the nth coil portion may be electrically connected in series in the order from the first to the nth coil portions.
In the above-described antenna component, preferably, the antenna component may be attached to a metal body for use.
According to the present disclosure, a large output can be obtained.
(Configuration of Antenna Component)
A configuration of an antenna component according to an embodiment is described below with reference to the drawings.
Hereinafter, the lengthwise direction of the antenna component 10 is defined as front-rear direction. The widthwise direction of the antenna component 10 is defined as left-right direction. The thickness direction of the antenna component 10 is defined as up-down direction. The front-rear direction, left-right direction, and up-down direction are perpendicular to each other. The front-rear direction, left-right direction, and up-down direction are directions defined for the sake of convenience and do not necessarily have to be the same as the front-rear direction, left-right direction, and up-down direction of the antenna component 10 in actual use.
The antenna component 10 is an antenna component for transmission in a short-range communication system in the low frequency (LF) range (30 kHz to 300 kHz) and is mainly used in a remote keyless system, in which a vehicle door is locked or unlocked by remote control. The antenna component 10 is typically mounted inside a door of the vehicle. Specifically, the antenna component 10 is configured to be attached on the back side of a door panel made of a material containing iron, although it should be appreciated that the metal in the material of the door panel can be another material besides iron.
As illustrated in
As illustrated in
Each of the flange portions 14a to 14f has a rectangular frame shape as seen from the front side in plan view, and they are arranged in this order from the front side to rear side. That is, each of the flange portions 14a to 14f is configured by forming a rectangular hole in a plate member being rectangular as seen from the front side in plan view, the hole extending through the plate member in the front-rear direction. The size of the rectangular hole is virtually the same as the size of the magnetic core 12 as seen from the front side in plan view.
The connecting portion 14g is an elongated member extending in the front-rear direction and connects the left-side edges of the flange portions 14a to 14f. The connecting portion 14h is an elongated member extending in the front-rear direction and connects the right-side edges of the flange portions 14a to 14f.
Preferably, the bobbin 14 having the above-described configuration is produced by integral molding performed on polybutylene terephthalate (PBT).
The magnetic core 12 is a stick-shaped member extending along the front-rear direction and having a rectangular parallelepiped shape as seen from the up side in plan view. One example of the magnetic core 12 may be produced by compression molding in which impalpable powder of a manganese-zinc ferrite or other amorphous magnetic materials is formed into a flat board shape and firing it.
As illustrated in
Hereinafter, as illustrated in
As illustrated in
The top surface and bottom surface of the magnetic core 12 in the regions E1 to E5 are exposed outside from the bobbin 14. The right surface and left surface of the magnetic core 12 are covered with the connecting portions 14h and 14g.
The coil antenna 16 is configured by winding a lead in which a surface of a core wire made of a conductive material, such as copper, is covered with an insulating material around the magnetic core 12. As illustrated in
The coil portion 16a is configured by winding a lead around the magnetic core 12 and connecting portions 14g and 14h in the region E1 and has a spiral shape. The coil portion 16b is configured by winding a lead around the magnetic core 12 and connecting portions 14g and 14h in the region E3 and has a spiral shape. The coil portion 16c is configured by winding a lead around the magnetic core 12 and connecting portions 14g and 14h in the region E5 and has a spiral shape. The coil portions 16a to 16c are wound in the same direction. The region E2 with no lead wound is present between the coil portion 16a and coil portion 16b. The region E4 with no lead wound is present between the coil portion 16b and coil portion 16c. Thus, the coil portions 16a to 16c are disposed such that they are spaced apart from each other and arranged in this order from the front side to rear side.
The connecting portion 16d connects the rear end of the coil portion 16a and the front end of the coil portion 16b. The connecting portion 16e connects the rear end of the coil portion 16b and the front end of the coil portion 16c. Thus, the coil portions 16a to 16c are electrically connected in series in this order.
The extended portion 16f is connected to the front end of the coil portion 16a. The extended portion 16g is connected to the rear end of the coil portion 16c.
The length d2 of the region E3 in the front-rear direction is shorter than each of the length d1 of the region E1 in the front-rear direction and the length d3 of the region E5 in the front-rear direction. Thus, the length of the coil portion 16b in the front-rear direction is shorter than that of each of the coil portions 16a and 16c in the front-rear direction. Accordingly, the number of turns of the coil portion 16b is smaller than that of each of the coil portions 16a and 16c. As shown in
The antenna component 10 having the above-described configuration is attached to a door panel with an adhesive, double-sided adhesive tape, or the like for use. The extended portions 16f and 16g in the antenna component 10 are connected to a signal generating circuit.
According to the above antenna component 10, a large output is obtainable. More specifically, a magnetic-field output of the antenna component is determined by the ampere-turn of the coil antenna defined by Expression (1) below.
Ampere-turn=Number of Turns×Coil Current (1)
If the number of turns is increased to have a large magnetic-field output in the antenna component, the inductance value is increased and the resonant frequency is reduced, and it cannot be used at a desired frequency. Accordingly, if the number of turns of the coil antenna is increased, it is difficult to have a large output of the antenna component at a desired frequency.
The present inventor conceived a method of increasing the output of the antenna component 10 while suppressing an increase in the inductance value of the coil antenna 16 by an experiment described below.
The present inventor produced a first sample and a second sample of the antenna component 110 illustrated in
According to the disclosed antenna component 10, when the antenna component 10 is attached to a metal body, such as a door panel, for use, a large output can be obtained. More specifically, in the transmission antenna component described in Patent Document 1, an increased number of turns leads to an increased inductance value and thus to a high Q factor in the transmission antenna coil. This results in a narrow resonance range and decreased broadness in the transmission antenna coil. The decreased broadness of the transmission antenna coil causes the output to tend to decrease because of the effects of the metal body positioned in the vicinity of the transmission antenna coil.
For the antenna component 10, in which the number of turns of the coil portion 16b is smaller than that of each of the coil portions 16a and 16c, as previously described, when the number of turns of the coil antenna 16 is increased, the inductance value of the coil antenna 16 does not easily increase. Accordingly, when the number of turns of the coil antenna 16 is increased to have a large output of the antenna component 10, the increase in the inductance value of the coil antenna 16 is suppressed. Thus, the increase in the Q factor of the coil antenna 16 is suppressed, and the decrease in the broadness of the antenna component 10 is suppressed. With the ensured broadness of the antenna component 10, when the antenna component 10 is positioned in the vicinity of a metal body, the decrease in the output of the antenna component 10 is suppressed. As described above, according to the antenna component 10, when the antenna component 10 is attached to a metal body, such as a door panel, for use, a large output can be obtained.
The metal body is a metal plate having first and second principal surfaces opposed to each other. The antenna component 10 is attached to the first principal surface of the metal body by adhesive fixing or by screws, for example. The area of the metal body is larger than that of the antenna component 10 when the metal body is seen from the first principal surface side in plan view. The metal body may preferably be disposed such that the antenna component 10 fully overlaps it when the metal body is seen from the first principal surface side. Depending on the specifications of the door panel, the metal body may have a cut or through-hole.
The antenna component according to the present disclosure is not limited to the antenna component 10, and any modification may be made without departing from the scope of the present invention.
Other coil portions may be added to the coil portions 16a to 16c, and thus the total number of coil portions may be four or more. When a first coil portion to an nth coil portion (n being an integer more than two) are disposed along the magnetic core, the number of turns of each of the second coil portion to the (n−1)th coil portion is less than smaller than that of each of the first coil portion and the nth coil portion. The first coil portion to the nth coil portion are arranged in this order from the front side to the rear side. When n is three according to an exemplary embodiment, the second coil portion is the (n−1)th coil portion.
The order in which the coil portions 16a to 16c are electrically connected in series is not limited to a numerical order of the first to nth coil portions. They may preferably be connected in the numerical order because the length of the connecting portion between the coil portions can be shortened.
The magnetic core 12 extends straight along the front-rear direction. The magnetic core 12 may curve.
As described above, the present disclosure is useful as an antenna component and in particular is advantageous in that a large output can be obtained.
Number | Date | Country | Kind |
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2014-007900 | Jan 2014 | JP | national |
The present application is a continuation of PCT/JP2014/083708 filed Dec. 19, 2014, which claims priority to Japanese Patent Application No. 2014-007900, filed Jan. 20, 2014, the entire contents of each of which are incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
20040252068 | Hall | Dec 2004 | A1 |
20070091007 | Sako | Apr 2007 | A1 |
20100164822 | Iwasaki | Jul 2010 | A1 |
20110241957 | Ohara | Oct 2011 | A1 |
20140198011 | Tsubaki | Jul 2014 | A1 |
Number | Date | Country |
---|---|---|
S59152703 | Aug 1984 | JP |
2005175965 | Jun 2005 | JP |
H04287407 | Jun 2005 | JP |
2007288345 | Nov 2007 | JP |
2012239020 | Dec 2012 | JP |
WO 2008056601 | May 2008 | WO |
Entry |
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International Search Report issued for PCT/JP2014/083708, dated Mar. 10, 2015. |
Written Opinion of the International Searching Authority issued for PCT/JP2014/083708, dated Mar. 10, 2015. |
Number | Date | Country | |
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20160315388 A1 | Oct 2016 | US |
Number | Date | Country | |
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Parent | PCT/JP2014/083708 | Dec 2014 | US |
Child | 15202811 | US |