JP2011049847A - Mobile wireless equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To disclose a method of reducing the power ratio absorption rate (a local SAR) in a mobile wireless equipment. <P>SOLUTION: When a mobile wireless equipment is used, a power feeding spring 140 for transmitting a wireless signal to an antenna structure 130 is arranged on a substrate surface on an opposite side of a side in the vicinity of the surface contacting with a human body. The power feeding spring 140 communicates a signal transmitted via a wiring pattern 160 through a power amplifier 112 from a communicating circuit 111 to the antenna structure 130. And the width of an extended end 150 of the wiring pattern for arranging the power feeding spring 140 is extended so as to be wider than a wiring width to that point. The extended end 150 is extended so that the length from a cross point of a vertical line, which is taken down from a contact between the power feeding spring 140 and the antenna structure 130 to substrate 110, to the most-distant end of the extended end 150 falls into a range of 1/20 of the length of a wavelength of a signal to be received and transmitted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a portable wireless device, and more particularly, to reduction of the power specific absorption rate of a human body.

In a portable wireless device typified by a cellular phone, when transmitting / receiving a wireless signal, there is a possibility that heat is generated by emitting a high-intensity microwave and the human body is affected. For this reason, in the mobile phone, it is desirable that the human specific power absorption rate (hereinafter referred to as SAR (SAR: Specific Absorption Rate)) is as low as possible.
In a mobile phone, a value called a local SAR is used, and the local SAR is required to be within a predetermined specified value. The local SAR refers to an average value of energy absorbed in a tissue per 10 g of a human body for 6 minutes when the human body is exposed to electromagnetic waves. The unit of local SAR is W / kg.

The local SAR standard value is determined for each country. For example, in the case of Japan, it is 2.0 W / kg or less, and in the case of the United States, the human body is not per 10 g of human tissue. It is obliged to design a wireless device so that it becomes 1.6 W / kg or less per 1 g of tissue.
Patent Document 1 discloses a technique for reducing local SAR by shifting the resonance frequency of an antenna. Patent Document 2 discloses a technique for reducing local SAR due to interference by providing two antenna elements, that is, a transmitting antenna, a receiving antenna, and two antenna elements so that the radiation characteristics of both antennas are orthogonal to each other. It is disclosed.

Japanese Patent Laid-Open No. 2002-217637 JP-T-2002-526956

Incidentally, as described above, although there is a technique capable of reducing the local SAR, it is needless to say that the local SAR can be reduced when designing the portable wireless device.
Accordingly, the portable wireless device according to the present invention aims to realize such reduction of the local SAR by using a method different from the above-described Patent Document 1 and Patent Document 2.

  In order to solve the above-mentioned problem, the present invention is provided with an antenna structure spaced apart from a substrate in a housing, and a wiring pattern is extended from the amplification stage of the communication circuit on the substrate to the vicinity of the antenna structure, A portable wireless device in which a wiring pattern and the antenna structure are connected via an electrically conductive member at an extended end, wherein the wiring pattern is a portion where the line width at the extended end is connected to the amplification stage side It is characterized by being formed wider than the line width in FIG.

  With the configuration as described above, in the portable wireless device, the wiring is set wide in the wiring portion to which the antenna structure is directly connected. Thereby, it is possible to suppress the current from being concentrated on a part of the wiring pattern at a time, and the current can be diffused at the above-described extension end, so that the reduction of the local SAR can be realized.

It is an external view of a mobile phone. It is a disassembled perspective view of a mobile phone. It is a figure which shows the structure at the time of seeing the arrangement | positioning of the board | substrate and antenna of a mobile telephone from the side. It is a three-plane figure which shows the structure of an antenna. It is a perspective view which shows a board | substrate, an antenna, and a feeding spring. It is a plane enlarged view of the part by which the electric power feeding spring connected with the antenna of the board | substrate of the side by which an antenna is arrange | positioned is arrange | positioned. It is a table | surface which shows the measured value of SAR according to the size of an extension end. It is a top view of a board | substrate at the time of making the shape of an extension end circular. It is a table | surface which shows the measured value of SAR when an extension end is made circular. It is a top view which shows the shape of other extension ends. It is a top view of the part by which the electric power feeding spring connected with the antenna of the board | substrate of the side by which the conventional antenna is distribute | arranged is arrange | positioned.

Hereinafter, a mobile phone which is an embodiment of a mobile wireless device according to the present invention will be described with reference to the drawings.
<Embodiment 1>
<Configuration>
FIG. 1 shows an external view of the mobile phone 100. As shown in FIG. 1, the mobile phone 100 is a straight type mobile phone.

  FIG. 2 is an exploded perspective view of the mobile phone 100. As shown in FIG. 2, the mobile phone 100 includes a first cover 101, a second cover 102, a substrate 110, and an antenna arrangement member 120 on which an antenna structure (hereinafter referred to as an antenna structure) 130 is arranged. The board 110 and the antenna arrangement member 120 are covered with a first cover 101 and a second cover 102. Although not shown, the substrate 110 is a multilayer substrate, on which various circuits and components necessary for the mobile phone 100 are arranged, and wiring patterns for connecting the circuits and components are stretched. The antenna arrangement member 120 is an insulating member and is mainly made of synthetic resin or the like.

FIG. 3 is a diagram showing a state where the exploded state shown in FIG. 2 of the mobile phone 100 is viewed from the right, and shows an arrangement relationship between the substrate 110 and the antenna arrangement member 120.
Since a strong radio signal is output from the antenna structure 130, it is desirable to dispose the antenna structure 130 in a direction away from the human body as much as possible in order to reduce the local SAR. Inside the housing of 100, it is arranged as far as possible from the substrate in a direction away from the human body in a usage pattern when making a call.

FIG. 4 is a three-view diagram illustrating the configuration of the antenna structure 130 and the antenna arrangement member 120. The upper diagram shown in FIG. 4 shows the side of the antenna arrangement member 120 close to the substrate 110, and the lower diagram shows the opposite side.
As shown in FIG. 4, the antenna structure 130 includes an excitation element 131 and a power feeding unit 132, and the power feeding unit 132 is formed so as to wrap around from one surface to the side surface of the antenna arrangement member 120 and another surface. . The excitation element 131 is provided on the one surface over a predetermined length that is a quarter wavelength of the wavelength of a signal to be transmitted and received.

  Returning to FIG. 3, the description will be continued. Since the signal transmitted from the antenna structure 130 is generated by a communication circuit disposed on the substrate 110, the communication signal of the substrate 110 is transmitted in order to transmit the signal from the wiring pattern of the substrate 110 to the antenna structure 130. A power supply spring 140 for bringing the wiring pattern into contact with the power supply portion 132 of the antenna structure 130 is soldered to the wiring pattern on the substrate 110. The feeding spring 140 is a conductive member, and is configured to come into contact with the feeding unit 132 of the antenna structure 130 as shown in FIG. In FIG. 4, the power supply spring 140 is in contact with the power supply unit 132 shown in the upper diagram.

FIG. 5 shows the substrate 110 and the antenna arrangement member 120 before assembly.
As shown in FIG. 5, a communication circuit 111 is disposed on the substrate 110, and the wiring pattern 160 extends from the communication circuit 111 to the vicinity of the antenna structure 130 via the power amplifier 112 that is an amplification stage. ing. The extended end 150 of the wiring pattern 160 is formed by extending the wiring width, as can be understood from FIG. In this specification, the extension end 150 refers to a region where the power supply spring 140 is disposed. That is, although the extension end 150 is labeled as an extension end, it is not completely the end of the wiring pattern 160. As shown in FIG. 5, the power supply spring 140 is connected from the end opposite to the power amplifier 112 of the wiring pattern 160. It should be noted that this includes a certain range that is sufficient for distribution.

FIG. 6 is a plan view when the substrate 110 in the state shown in FIG. 5 is viewed from above. As shown in FIG. 6, the extended end 150 shown in the first embodiment is formed in an L × M square shape. The dimensions of L and M will be described later.
Since the extended end 150 is a part of the wiring pattern 160, the extended end 150 is made of a conductive member (for example, copper (copper foil)), and may function as an antenna depending on its shape and size. I cannot deny. Therefore, the extension 150 is provided with the following restrictions. That is, it is assumed that a perpendicular is drawn from the contact 141 between the feeding spring 140 and the feeding part 132 of the antenna structure 130 to the substrate 110, from the intersection of the perpendicular and the substrate 110 to the farthest end of the extension end 150. This is a restriction that the length (arrow 142 in FIG. 6) is 1/20 or less of the wavelength of the signal transmitted and received by the antenna structure 130.

This is because the length in the longitudinal direction of the excitation element 131 of the antenna structure 130 is usually set to be a quarter wavelength of the wavelength of the signal transmitted and received by the antenna structure 130. As a result of determining that the length of the ¼ wavelength is up to 20% as a length that will not sometimes affect, ¼ × 0.2 = 1/20 or less.
As described above, by configuring the extended end 150 formed by extending the end portion of the wiring pattern 160 opposite to the portion connected to the power amplifier 112, the mobile phone shown in the first embodiment is provided with the local SAR. Realize the reduction. 5 and 6 show only the communication circuit 111 and the power amplifier 112, other elements and circuits may be interposed between them.
<Discussion>
Here, the effect of reducing the local SAR when the extension end 150 is expanded to a square as described above will be described.

  In describing the effect of reducing the local SAR, the shape of the conventional extension end will be described with reference to FIG. Conventionally, the extended end 150 is merely a part of the wiring pattern, and has only the same width as the wiring pattern up to that point. As shown in FIG. 11, the conventional extension end 150 has a feeding spring 140 soldered to an area of about 1 mm × 3 mm (L = 1 mm, M = 3 mm), and a radio signal is transmitted to the antenna via the feeding spring 140. Was configured to be transmitted.

Now, the effect of reducing the local SAR when the extension end 150 is expanded to a square by comparing with the case where the extension end 150 is a square of 1 mm × 3 mm will be described with reference to FIG.
FIG. 7 shows measured values of the local SAR at each size of the extension end 150. The table shown in FIG. 7 shows the total radiated power in free space (TRP Free Space [dBm] in FIG. 7) and the local SAR in the state where the mobile phone 100 is placed on the left cheek of the person, that is, in the state of making a call. The actual measurement value (SAR [W / kg] @Touch left in FIG. 7) and the decibel conversion value when TRP is 20 dBm (SAR [W / kg] @Touch left 20 dBm conversion in FIG. 7) are shown. The total radiated power is sometimes referred to as total radiated power. Further, the reason why the local SAR TRP shows a decibel conversion value at 20 dBm is that there is a variation in the total radiated power, so that the comparison is facilitated by conversion to 20 dBm. Hereinafter, the decibel conversion value when TRP is 20 dBm is referred to as “20 dBm conversion value”.

  In FIG. 7, the measured values in 25 channels (1851.25 MHz), 600 channels (1880.00 MHz), and 1175 channels (1908.75 MH) are shown. The actual measurement values are actual measurement values when the size of the extension end 150 (L × M) is 1 mm × 3 mm, 3 mm × 3 mm, 4 mm × 4 mm, 5 mm × 5.5 mm, respectively. The actual measurement value of 1 mm × 3 mm is that of a conventional mobile phone.

  First, in the case of the conventional extension end, that is, when the extension end 150 is 1 mm × 3 mm, the total radiated power is 22.2 dBm in the case of 25 channels, and the local SAR at this time is a converted value of 20 dBm. Thus, it is 0.92 W / kg. On the other hand, when the extension end 150 is expanded as in the present invention, the total radiated power in the case of 3 mm × 3 mm, 4 × 4 mm, 5 × 5 mm is 22.3 dBm, 22.0 dBm, 22 Although it does not change so much as .1 dBm, the local SAR is 0.78 W / kg, 0.78 W / kg, and 0.71 W / kg, which are 20 dBm equivalent values, which are smaller than the conventional local SAR.

  Below the 20 dBm conversion value of the local SAR in FIG. 7, the difference between the extended end of each size in each channel and the conventional case is shown, but as in the 1-0 column of 25 channels When the extension end 150 is a 3 mm × 3 mm square, it is clear that the local SAR of 0.14 W / kg has been successfully reduced. It can be understood that the local SAR is reduced by 0.08 W / kg and 0.22 W / kg in the case of 600 channels and 1175 channels, respectively.

Even when the extension end 150 is a square of 4 mm × 4 mm, as shown in the column 2-0 in FIG. 7, similarly, 0.14 W / kg, 0 in each of the 25 channel, 600 channel, and 1175 channel .17 W / kg, 0.25 W / kg and succeeded in reducing local SAR.
This is the same even when the extension end 150 is 5 mm × 5.5 mm. As shown in the column 3-0 in FIG. 7, 0.21 W / kg in each of the 25 channel, 600 channel, and 1175 channel. , 0.21 W / kg, 0.28 W / kg and succeeded in reducing local SAR.

From this, generally, the greater the degree of expansion of the extension end 150, the more local SAR can be expected to reduce.
<Embodiment 2>
In the above-described embodiment, the extension end has been described as having a rectangular shape. However, it is not necessary to provide the wiring pattern with a uniform uniform width. In the second embodiment, a case where the extended end is formed in another shape will be described.
<Configuration>
FIG. 8 shows a plan view of the substrate 110 when the extended end 150 of the substrate 110 is circular.

As shown in FIG. 8, the extension end 150 according to the second embodiment has the perpendicular line and the substrate 110 when assuming that the perpendicular line is dropped on the substrate 110 from the contact point between the power supply spring 140 and the power supply unit 132 of the antenna structure 130. It is a circle centered on the intersection. As shown in the first embodiment, the radius of the circle is desirably 1/20 wavelength or less of the wavelength of a signal to be transmitted / received. In addition, although described as a restriction on the radius of the circle, this is based on the assumption that the extended end 150 is perpendicular to the substrate 110 from the contact point between the feeding spring 140 and the feeding portion 132 of the antenna structure 130. And the restriction on the distance from the intersection point to the farthest end of the extended end 150 when it is deviated from the center of the circle. Become.
<Discussion>
Now, the effect of reducing the local SAR when the extension end 150 is circular in this way will be described.

Since the format of the table is the same as that shown in FIG. 7, the details of each item are omitted here.
FIG. 9 shows the total of each of the channels when the radius of the extended end 150 is 3 mm, 5 mm, and for comparison, when the conventional extended end 150 is 1 mm × 3 mm. The radiated power, the local SAR, and the 20 dBm equivalent value of the local SAR are shown.

  In the columns 1-0 and 2-0 in FIG. 9, the difference value from the conventional case when the radius of the extended end 150 is 3 mm and the difference value from the conventional case when the radius is 5 mm are shown. ing. As can be seen from the difference value, for example, when the radius is 3 mm, the local SAR is a converted value of 20 dBm, which is 0.26 W / kg, 0. There is a reduction effect of 22 W / kg and 0.28 W / kg. In addition, when the radius is 5 mm, the local SAR is 20 dBm converted value, which is 0.39 W / kg, 0.35 W / kg, 0.42 W / kg in order of 25 channels, 600 channels, and 1175 channels, respectively. There is a reduction effect.

Even when the shape of the extended end 150 is a circle, it can be said that the effect of reducing the local SAR is higher when the distance from the contact point between the feeding spring 140 and the antenna structure 130 to the end of the extended end 150 is increased. .
<Supplement>
Although the present invention has been described in the above embodiment, the present invention is of course not limited thereto. Hereinafter, various modified examples included in the present invention other than the above-described embodiment will be described.
(1) In the above embodiment, the straight type mobile phone has been described as an example. However, this is not limited to the straight type, and the area of the extension end is provided wider than the conventional one at the extension end serving as the antenna contact point on the substrate. It may be a foldable or slide type mobile phone.
(2) In the above embodiment, a member called a power supply spring is used to connect the substrate and the antenna. However, this may be any member that can connect the substrate and the antenna through a path that is close to the shortest. A configuration may be adopted in which one conductive pin is soldered to the extension end and the other end of the pin is in contact with the antenna. In short, the shape is not limited as long as it is a conductive member that connects the extended end 150 of the wiring pattern and the antenna structure 130.
(3) In the above-described embodiment, the case of a square or a circle has been described. However, this is not limited to a square or a circle, and the end farthest from the contact point between the feeding spring and the antenna on the extended end on the substrate 110 is the same. It is sufficient that the distance between the contact and the end is equal to or less than 1/20 of the wavelength calculated from the resonance frequency of the signal transmitted and received by the antenna.

  If the condition is satisfied, the shape of the extended end may be, for example, an ellipse or a shape as shown in FIGS. In FIG. 10, each arrow connects a point when it is assumed that a perpendicular is dropped from the contact point between the feeding spring 140 and the antenna structure 130 to the substrate and the farthest end portion of the extension end 150 from the point. Therefore, it is sufficient that the length of the arrow is 1/20 or less of the wavelength of the signal transmitted and received by the antenna structure 130.

In the cellular phone, as shown in FIG. 10D, a method of providing a power supply spring 145 that is paired with the power supply spring 140 and grounding the power supply spring 145 in order to stabilize the resonance frequency of the antenna. May be used. The feeding spring 145 is configured to contact the antenna structure 130.
The power supply spring 145 is a conductive member and is soldered to the extended end 151. The extended end 151 is connected to the solid ground layer through a hole. Originally, the extension end 151 only needs to have a space enough to install the power supply spring 145, but it is possible to reduce the local SAR by slightly increasing the area.

  The mobile wireless device according to the present invention can be used as a mobile phone having a low SAR.

100 cellular phone 101 first cover 102 second cover 110 substrate 111 communication circuit 112 power amplifier (amplification stage)
120 Antenna Arrangement Member 130 Antenna Structure 131 Excitation Element 132 Power Supply 140, 145 Power Supply Spring (Conductive Member)
150, 151 Extension end 160 Wiring pattern

Claims (4)

An antenna structure is provided apart from the substrate in the housing, and a wiring pattern is extended from the amplification stage of the communication circuit on the substrate to the vicinity of the antenna structure, and the wiring pattern and the antenna structure are extended at the extended end. Is a portable wireless device connected via a conductive member,
The wiring pattern is formed so that a line width at an extended end thereof is wider than a line width at a portion connected to the amplification stage side. The line width of the extended end of the wiring pattern is the farthest of the extended end from the intersection of the substrate and the perpendicular when it is assumed that a perpendicular is dropped on the substrate from the contact point between the conductive member and the antenna structure. The portable wireless device according to claim 1, wherein a length to the end is 1/20 or less of a wavelength of a signal to be transmitted / received. The portable wireless device according to claim 2, wherein the extended end of the wiring pattern is square. The portable wireless device according to claim 2, wherein the extended end of the wiring pattern is circular or elliptical.

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