JP2011188459A - High frequency coupler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency coupler that is immune to a traverse shift, while achieving small-sizing and thinning, in the high frequency coupler being used for communicating a high frequency signal. <P>SOLUTION: A high frequency coupler includes: a circuit board; and an antenna element which is formed on either a front surface or an inner surface of the circuit board and having shape which turns around along the circle while alternately repeating a first route extending from the inside of the circle to the outside thereof and a second route extending from the outside of the circle to the inside thereof when a circle is drawn on the surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-frequency coupler used for high-frequency signal communication.

  In recent years, proximity wireless transfer technology based on broadband wireless technology has been proposed and is expected to become popular in the future. This proximity wireless transfer technology is a technology for performing contactless communication via an antenna using an induction electric field. This proximity wireless transfer technology is a technology capable of transferring a large amount of data at a high speed in a short time, and is suitable for transferring a large amount of data such as music data or moving image data. In addition, this proximity wireless transfer technology is assumed to have a communication distance of several centimeters or less, and has an advantage that the possibility of data leakage during communication is low.

  As means for realizing such a proximity wireless transfer technology, for example, a high-frequency coupler having a structure in which a coupling electrode is formed of a linear conductor and folded in a coil shape has been proposed (Patent Document 1).

  A structure in which a high-frequency coupler is formed on a substrate has also been proposed (Patent Document 2).

JP 2009-100111 A JP 2008-271606 A

  This high-frequency coupler is assumed to be mounted on a small device such as a mobile phone, and there is a strong demand for downsizing and thinning.

  However, in the case of the high-frequency coupler having a structure in which the linear conductor disclosed in Patent Document 1 is folded in a coil shape, the height of the coil is required although it is folded in a coil shape. It is difficult to reduce the size and thickness to a level sufficient for mounting on such a small device.

  Another requirement of the high frequency coupler is to increase the tolerance of lateral deviation between the high frequency coupler on the transmission side and the high frequency coupler on the reception side. When the two high-frequency couplers on the transmission side and the reception side are correctly aligned with each other, even if sufficient coupling strength is obtained and communication between them is possible, the two high-frequency couplers are relatively If the bond strength is suddenly weakened when it is shifted to the side, it becomes difficult to use.

  For this reason, when the two high-frequency couplers are shifted relative to each other, the lateral distance at which sufficient coupling strength is obtained becomes a problem.

  The high frequency coupler disclosed in Patent Document 2 is formed on a substrate and is superior in terms of miniaturization as compared with the high frequency coupler disclosed in Patent Document 1, but as shown in a comparative example described later. It is considered that the tolerance for lateral displacement is lowered.

  It is an object of the present invention to provide a high-frequency coupler that is more resistant to lateral displacement while being reduced in size and thickness.

  The high-frequency coupler of the present invention that achieves the above object is formed on a surface of a circuit board and either the surface or the inner surface of the circuit board, and when the circle is drawn on the surface, An antenna element having a shape that circulates along the circle while alternately repeating a first path extending from the inside to the outside and a second path extending from the outside to the inside of the circle is provided.

  Here, in the high frequency coupler of the present invention, the first path and the second path that constitute the antenna element are both linearly extending paths, and the first path and the second path that are adjacent to each other are mutually connected. They may be alternately repeated in contact with each other with an angle between them.

  Furthermore, the high-frequency coupler according to the present invention preferably includes a second antenna element that circulates around the antenna element and is formed on the surface or the inner surface of the circuit board.

  The high-frequency coupler of the present invention may have a loop antenna element that circulates around the antenna element on the surface of the circuit board.

  According to the present invention, even when the transmission high-frequency coupler and the reception high-frequency coupler having the same shape of the antenna element are overlapped with each other and shifted laterally, the transmission and reception are parallel to each other. A pair of line segments close to each other is formed, so that strong coupling strength is maintained even if there is a lateral shift.

It is the figure which showed the surface (A) and back surface (B) of the high frequency coupler of embodiment of this invention. It is the figure which showed the state (A) and the state shifted to the side (B) where two circuit boards for transmission and reception each formed with an antenna element overlap each other. It is the figure which showed the state which shifted the circular antenna element sideways. It is the figure which showed the state which shifted the star-shaped antenna element sideways. It is the figure which showed the relationship between the shift amount to a side, and coupling strength. It is the figure which showed the various modifications of embodiment shown in FIG. It is the figure which showed the modification of the antenna element.

  Embodiments of the present invention will be described below.

  FIG. 1 is a view showing a front surface (A) and a back surface (B) of a high-frequency coupler according to an embodiment of the present invention.

  As shown in FIG. 1A, the high-frequency coupler 10 includes a circuit board 20, a star-shaped antenna element 30 formed on the surface of the circuit board 20, and a star shape on the surface of the circuit board 20. A loop antenna element 40 formed so as to circulate around the antenna element 30. Further, as shown in FIG. 1B, a ground surface 33 is widely formed at the center of the back surface of the circuit board 20, and the star antenna element 30 is formed in the opening from which the ground surface 33 is cut. A power feeding section 34 is formed. One end of the star-shaped antenna element 30 formed on the surface of the circuit board 20 is connected to the power feeding portion 34 formed on the back surface of the circuit board 20 through the through hole 38, and the other end of the star-shaped antenna element 30 is formed. Is connected to the ground surface 33 on the back surface of the circuit board 20 through the through hole 39.

  In addition, two power feeding portions 41 for the loop antenna element 40 are formed on the back surface of the circuit board 20. Both ends of the loop antenna element 40 formed on the surface of the circuit board 20 are connected to the two power feeding portions 41 on the back surface of the circuit board 20 through the through holes 49, respectively.

The star-shaped antenna element 30 includes a first path 31 extending from the inside to the outside of the circle 37 and a second path 32 extending from the outside to the inside of the circle 37 when the circle 37 is drawn on the surface of the circuit board 20. And alternately and repeatedly around the circle 37. The antenna element 30, as shown in FIG. 1, a size of the antenna elements having a width of about of about 10 mm, it is possible to perform high-speed communications at a wavelength of 4～5GH _Z bands.

  In the antenna element 30 shown in FIG. 1, the first path 31 and the second path 32 are both linearly extending paths, and the first path 31 and the second path 32 adjacent to each other are mutually connected. It repeats alternately with an angle in between and touching each other.

  The loop-shaped antenna element 40 is formed on the surface of the circuit board 20 so as to go around the star-shaped antenna element 30 as described above. Both ends of the loop antenna element are connected to two power feeding portions 41 formed on the back surface of the circuit board 20 through a pair of through holes 49.

  The loop antenna element 40 is used as a so-called RFID radio antenna.

  FIG. 2 is a diagram showing a state (A) in which two circuit boards for transmission and reception, each having an antenna element formed thereon, are overlapped (A) and a state (B) in which they are shifted laterally.

  Here, consideration is given to a case where two star-shaped antenna elements 30 shown in FIG. 1 are prepared for transmission and reception, and are relatively shifted laterally as shown in FIG. 2 (A) to FIG. 2 (B). To do. Here, the interval between the two antenna elements for transmission and reception is 1 mm.

  FIG. 3 is a diagram showing a state in which a circular antenna element is shifted laterally. This circular antenna element is a comparative antenna element compared with the embodiment of the present invention.

  The coupling strength between the transmitting antenna element and the receiving antenna element is roughly determined by the length of a pair of line segments that are close to each other and extend parallel to each other and the degree of proximity.

  When the two antenna elements 50A and 50B for transmission and reception are slightly shifted as shown in FIG. 3A, the antenna element 50A for transmission and the antenna for reception are placed in the upper and lower parts of FIG. 3A. There are parallel line segment pairs that are close to each other with the element 50B. However, if they are largely shifted as shown in FIG. 3B, the parallel parts are separated from each other, and only weak coupling strength is obtained.

  FIG. 4 is a diagram showing a state in which the star-shaped antenna element is shifted laterally.

  As shown in FIG. 4A, when the two antenna elements 60A and 60B for transmission and reception are slightly shifted, the entire circumference between the antenna element 60A for transmission and the antenna element 60B for reception is almost the entire circumference. There are parallel line segments that are close to each other. 4B, line segment pairs that are close to each other and parallel to each other exist as shown by a dotted line in FIG. 4B. Therefore, a strong coupling strength can be obtained even if it is greatly displaced laterally as shown in FIG.

  FIG. 5 shows the relationship between the lateral shift amount and the coupling strength in the star-shaped antenna element (example) shown in FIG. 1 and the circular antenna element (comparative example) capable of transmitting and receiving in the same wavelength region. FIG.

"Example" is a star shape as shown in FIG. 1, has a width of about 10 mm, an antenna element whose length is determined so as to transmit and receive radio waves 4～5GH _Z bands. Furthermore, "comparative example" is a circular plate-shaped antenna elements, as in the "Examples", is the length to transmit and receive radio waves in the frequency band of 4～5GH _Z are determined.

  Further, in both the “Example” and “Comparative Example”, the distance in the facing direction between the transmitting antenna element and the receiving antenna element is 1 mm (see FIG. 2).

  In FIG. 5, the horizontal axis indicates the relative shift distance [mm], and the vertical axis indicates the coupling strength [dB]. The coupling strength [dB] is expressed in decibels (dB) of the power transmitted to the receiving antenna element with respect to the power input to the transmitting antenna element.

Here plots the binding strength, in the frequency band of the peaks in the shifting distance of the coupling strength of each frequency band when were further divided into a plurality of frequency bands the frequency band of 4~5GH _Z.

  In the case of the comparative example shown by the broken line in FIG. 5, the bond strength is greatly reduced at a shift distance of about 10 mm or more, whereas in the case of the example, a sharp decrease in the bond strength as in the comparative example is seen. Absent. That is, in the case of the embodiment, even if the receiving antenna element is arranged at a position considerably deviated from the transmitting antenna element, communication is possible between them, and the practicality is excellent.

  FIG. 6 is a diagram showing various modifications of the embodiment shown in FIG.

  A high-frequency coupler 10A shown in FIG. 6A is an example in which a star-shaped antenna element 30A, a ground plane 33A, and a power feeding portion 34A are all formed on the same surface of the circuit board 20A.

  Thus, the high frequency coupler of the present invention can also form all elements on only one surface of the circuit board.

  Further, in the high frequency coupler 10B shown in FIG. 6B, all elements of the star-shaped antenna element 30B, the ground surface 33B, and the power feeding portion 34B are formed on the same surface of the circuit board 20B as in FIG. 6A. In this example, an opening 331B is formed in the ground surface 33B, and the antenna element 30B is disposed in the opening 331B.

  Further, in the high frequency coupler 10C shown in FIG. 6C, as in FIGS. 6A and 6B, the star-shaped antenna element 30C, the ground surface 33C, and the feeding portion 34C are formed on the same surface of the circuit board 20C. Further, similarly to FIG. 6B, the ground surface 33C spreads so as to surround the antenna element 30C. However, in FIG. 6B, the opening 331B surrounding the antenna element 30B has a partially circular arc shape, and in FIG. 6C, the opening 331C surrounding the antenna element 30C is rectangular. .

  As shown in FIG. 1 and FIGS. 6A to 6C, the antenna element and the ground plane can be arranged in various forms.

  FIG. 7 is a diagram illustrating a modification of the antenna element.

  In the case of the antenna element 30 shown in FIG. 1, the first path 31 and the second path 32 are formed in the circle 37 while being alternately in contact with each other at an angle between the inside and the outside of the circle 37. It is circling along.

  On the other hand, in the case of the antenna element 30D shown in FIG. 7, the first path 31D and the second path 32D are in direct contact with each other while forming an angle inside the circle 37D, but the first path 31D and the second path 32D are outside the circle 37D. The path 31D and the second path 32D are not in direct contact with each other, but are connected via a line segment 35D extending in parallel with the circle 37D. Alternatively, the first path 31D and the second path 32D may be connected via a curve instead of the line segment 35D. Instead of being outside the circle 37D, it may be connected via a line segment or a curve inside the circle 37D, or both outside and inside the circle 37D.

  In the present invention, the first route and the second route are not necessarily directly connected as described above.

  In the present embodiment, the star-shaped antenna element is formed on the surface of the circuit board, but may be formed on the inner surface of the circuit board.

10, 10A, 10B, 10C High frequency coupler 20, 20A, 20B, 20C Circuit board 30, 30A, 30B, 30C, 30D, 50A, 50B, 60A, 60B Antenna elements 31, 31D First path 32, 32D Second path 33, 33A, 33B, 33C Ground plane 34, 34A, 34B, 34C, 41 Feeding portion 35D Line segment 37, 37D Circle 38, 39, 49 Through hole 40 Loop antenna element 331B, 331C Opening

Claims (3)

A circuit board;
A first path formed on either the surface or the inner surface of the circuit board and extending from the inside to the outside of the circle when a circle is drawn on the surface, and extending from the outside to the inside of the circle An antenna element having a shape that circulates along the circle while alternately repeating the second path.   The first path and the second path are both linearly extending paths, and the first path and the second path adjacent to each other form an angle between each other and contact each other and repeat alternately. The high frequency coupler according to claim 1.   3. The high frequency coupler according to claim 1, further comprising a loop antenna element that circulates around the antenna element on a surface of the circuit board.

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