JP2003008321A - Antenna assembly for portable terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an antenna provided in a metal enclosure from being influenced by high frequency currents flowing on a ground conductor of a circuit board to avoid deterioration of the antenna efficiency. SOLUTION: The antenna assembly for portable terminals having a circuit board 13 having a ground conductor 14, a conductive case 11 and antenna 15 connected to the ground conductor 14 comprises insulating means (an annular conductor 18 and an inductor 21) disposed between the conductive case 11 and the ground conductor 14 of the circuit board 13 against high frequency currents for operating the antenna 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile terminal antenna device provided in a mobile wireless device such as a mobile phone.

[0002]

2. Description of the Related Art FIG. 4 shows, for example, JP-A-11-34086.
FIG. 7 is a schematic exploded perspective view showing a conventional mobile terminal antenna device described in Japanese Patent Publication No. In the figure, 1 is a metal front case, 2 is a circuit board, 3 is a resin rear case, the circuit board 2 is housed in the resin rear case 3, and the resin rear case 3 and the metal rear case By combining the front case 1 with the front case 1, the housing of the portable wireless communication device is assembled.

Reference numeral 4 is a metal contact provided on the circuit board 2, 5 is an antenna feeding point on the circuit board 2, and 6 is a portion of the circuit board 2 near the antenna feeding point 5. This is a provided ground surface, and the contactor 4 is arranged on this ground surface 6, and the contactor 4 is connected to a portion (contactor connection portion) 1a of the metal front case 1. Reference numeral 7 denotes a projecting antenna attached to the resin rear case 3, and the antenna 7 is a circuit inside the resin rear case 3 from an antenna mounting hole 8 opened on the top surface of the resin rear case 3. It is connected to the antenna feeding point 5 on the substrate 2.

Next, the operation will be described. By connecting the contactor 4 on the circuit board 2 to the portion 1a of the metal front case 1, the metal front case 1 and the ground surface 6 of the circuit board 2 are electrically connected to each other, and the antenna feeding point 5 to the antenna 7 is connected. A ground current that is paired with the flowing current is guided to the metal front case 1, and the metal front case 1 functions as a radiating element.

[0005]

Since the conventional antenna device for a mobile terminal is constructed as described above, a metal contactor for electrically connecting the metal front case 1 and the ground surface 6 of the circuit board 2 to each other. Since 4 is required, there is a problem that a contact failure is likely to occur, a conduction failure occurs when viewed at a frequency at which the antenna is operated, which causes deterioration of antenna efficiency. Further, in recent years, due to the trend toward weight reduction of mobile phones, magnesium alloy is frequently used as the material of the metal front case 1. However, in the case of magnesium alloy, an oxide film is likely to be formed on the surface, and the influence of the oxide film. However, there is a problem that it becomes difficult to obtain perfect continuity.

The present invention has been made to solve the above problems, and an object thereof is to obtain an antenna device for a mobile terminal, which can prevent the efficiency deterioration of an antenna provided in a metal casing. .

Further, the present invention is for a portable terminal which can prevent the deterioration of the efficiency of the antenna even in the case of a two-fold type portable terminal comprising a combination of a plurality of circuit boards and one or a plurality of cases. The purpose is to obtain an antenna device.

Further, the present invention provides a portable terminal antenna device capable of reliably preventing a high frequency current flowing through a ground conductor of a circuit board from flowing to the case side and further improving antenna efficiency. With the goal.

A further object of the present invention is to provide an antenna device for a mobile terminal capable of reliably interrupting a high frequency current flowing through a ground conductor of a circuit board at a conductive portion between a case and the circuit board.

A further object of the present invention is to obtain an antenna device for a mobile terminal in which an antenna can be arranged by utilizing a gap formed by a plurality of circuit boards.

A further object of the present invention is to obtain an antenna device for a mobile terminal which can reduce the weight of the case.

[0012]

An antenna device for a mobile terminal according to the present invention comprises a circuit board having a ground conductor, a case having conductivity, and an antenna connected to the ground conductor. In the device, an insulating means against a high frequency current for operating the antenna is provided between the case and the ground conductor of the circuit board.

An antenna device for a mobile terminal according to the present invention includes a plurality of circuit boards having ground conductors, a linear conductor bundle connected between the circuit boards, and one or a plurality of cases having conductivity. And an antenna connected to the ground conductor, and insulating means for operating a high frequency current for operating the antenna is provided between the case and the ground conductor of the circuit board.

In the antenna device for a portable terminal according to the present invention, an insulating means electrically insulated from the ground conductor of the circuit board is provided in the conductive portion between the case and the circuit board.

In the portable terminal antenna device according to the present invention, the conducting portion between the case and the circuit board is DC-connected to the ground conductor of the circuit board by an inductor.

The antenna device for a mobile terminal according to the present invention has an antenna arranged in a gap formed by a plurality of circuit boards.

In the portable terminal antenna device according to the present invention, the case is made of a magnesium alloy.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. 1 is a schematic exploded perspective view showing an antenna device for a mobile terminal according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 11 denotes a front case for a mobile terminal such as a mobile phone, which is made of a metal material such as a magnesium alloy and has conductivity. A rear case 12 is paired with the front case 11 and is made of a dielectric material such as ABS resin. Reference numeral 13 is a circuit board, 14 is a ground (ground conductor) provided on the circuit board 13, 15 is a planar antenna integrally formed on the circuit board 13, 16
Is a high frequency voltage source connected between the ground 14 and the antenna 15.

In the above, the circuit board 13 is assembled and set in the front case 11, and the front case 1
1 and the rear case 12 are combined to form a circuit board 13 by the front case 11 and the rear case 12.
The portable terminal case is sandwiched and held. At this time, the front case 11 and the ground 14 of the circuit board 13 are insulated from each other by a high frequency for operating the antenna 15. The high frequency insulating means will be described with reference to FIG.

FIG. 2 is a schematic perspective view showing a state in which high-frequency insulating means is provided in the antenna device for a portable terminal of FIG. 1, and the same components as those in FIG. Omit it. In FIG. 2, reference numeral 17 denotes a circuit board 1 which is integrally formed on the inner bottom portion of the front case 11 having conductivity.
3 is a pedestal on which the pedestal 3 is seated, and the pedestal 17 is electrically connected to the front case 11. 18 is a circuit board 13
A ring-shaped conductor provided on the
8 and the ground 14 on the circuit board 13 are electrically insulated, and the insulation can be easily realized by the etching pattern of the circuit board 13. Therefore, the ring-shaped conductor 18 serves as a constituent element of an insulating means against a high frequency current flowing on the ground 14 of the circuit board 13.

Reference numeral 19 denotes a screw insertion hole which is opened in the central portion of the ring-shaped conductor 18 and is positioned corresponding to the pedestal 17,
Is a metal screw that is screwed into the pedestal 17 through the screw insertion hole 19 and fastens and fixes the circuit board 13 to the pedestal 17. The head of the screw 20 is the ring-shaped conductor 1
It comes in contact with 8. Reference numeral 21 is an inductor that connects the ground 14 on the circuit board 13 and the ring-shaped conductor 18. The inductor 21 is for connecting the ground 14 and the front case 11 to each other by direct current as an ESD countermeasure, and has a function of preventing a high-frequency current on the ground 14 of the circuit board 13 from flowing to the front case 11 side. Therefore, also in the case of the inductor 21, it is an element that constitutes an insulating means against the high frequency current on the ground 14. The circuit board 13 shown in FIG.
The circuit board 13 has the same configuration as that of the circuit board 13 shown in FIG. 1, and has the antenna 15 and the high frequency voltage source 16 shown in FIG.

Next, the operation will be described. The high-frequency voltage source 16 in FIG. 1 excites a high-frequency current on the antenna 15, and the high-frequency current is induced not only on the antenna 15 but also on the ground 14 of the circuit board 13 to the same extent. Here, the front case 11 and the circuit board 1
When the ground 14 of 3 is electrically connected at a certain contact point, a high-frequency current flows at the contact point so that the ground 14 and the front case 11 have the same potential. When the contact point is defective, the high-frequency current resistance is generated there, and the high-frequency power is consumed by this resistance value, so that the efficiency of the antenna 15 deteriorates. Since it is insulated by the high-frequency components that operate the antenna 15, loss of the high-frequency current flowing between them does not occur and the antenna 1
It is possible to prevent the efficiency deterioration of item 5.

That is, in FIG. 2, the ring-shaped conductor 18 insulated from the ground 14 of the circuit board 13 and the front case 11 are electrically connected by the metal screw 20 to connect the front case 11 and the circuit board 13. A conduction part is configured. As a result, the ring-shaped conductor 18 and the front case 11 are kept at the same potential, and the ring-shaped conductor 18 and the ground 14 of the circuit board 13 are connected by the inductor 21. With proper setting, the ring-shaped conductor 18 and the ground 14 are insulated from the high frequency current flowing through the ground 14.

Here, since the front case 11 and the ring-shaped conductor 18 are connected by the metal screw 20, there is a possibility that conduction failure due to high frequency may occur at the connection portion. Since the high frequency current of 1 is cut off by the inductor 21, the efficiency of the antenna 15 does not deteriorate due to the high frequency.

According to the first embodiment described above, the ring-shaped conductor 18 electrically insulated from the ground 14 is provided on the circuit board 13, and the ring-shaped conductor 18 is connected to the ground 14.
And the inductor 21 are connected to each other, and a screw insertion hole 19 is provided at the center of the ring-shaped conductor 18 insulated from the ground 14 of the circuit board 13 as described above. Since the circuit board 13 and the front case 11 are configured to be fastened and connected with each other by the screw 20,
The high-frequency current flowing through the ground 14 on the circuit board 13 does not flow through the front case 11, and the efficiency of the antenna 15 can be prevented from deteriorating. In addition, the ring-shaped conductor 18 is the circuit board 13.
In addition to being insulated from the upper ground 14, the ring-shaped conductor 18 and the ground 14 are DC-connected by the inductor 21.
The high-frequency current above causes the ring-shaped conductor 18 and the screw 2 to
0 is surely blocked from the conducting portion between the front case 11 and the circuit board 13 and no high-frequency current flows in the conducting portion, so that the efficiency deterioration of the antenna 15 can be prevented more reliably. There is. further,
The ring-shaped conductor 18 serving as a means for insulating high-frequency current in the conductive portion between the front case 11 and the circuit board 13.
Has an effect that it can be easily formed by the etching pattern of the circuit board 13.

Embodiment 2. FIG. 3 is a schematic exploded perspective view showing a two-fold type portable terminal antenna device according to a second embodiment of the present invention. In FIG. 3, 31 is an upper front case, 32 is an upper rear case, 33 is an upper circuit board sandwiched and held by the upper front case 31 and the upper rear case 32, 34 is a lower front case, and 35 is a lower rear case. Is a lower circuit board sandwiched and held by the lower front case 34 and the lower rear case 35, and the ground 33a of the upper circuit board 33 and the ground 36a of the lower circuit board 36.
Are connected by a linear conductor bundle 37 which is a signal line for transmitting a signal between the circuits of the two circuit boards 33 and 36. Three
Reference numeral 8 denotes an antenna arranged in a gap between the lower rear case 35 and the lower circuit board 36, and 39 denotes a high frequency voltage source connected between the antenna 38 and the ground 36a of the lower circuit board 36.

In the above, the upper front case 31 is made of a metal material such as magnesium alloy, and the upper rear case 32, the lower front case 34 and the lower rear case 35 are made of a dielectric material such as ABS resin. Then, the upper circuit board 33 is sandwiched and held by the upper front case 31 and the upper rear case 32, and the upper front case 31 and the upper rear case 32 are united to assemble the upper casing of the mobile terminal (mobile phone). To be Further, the lower circuit board 36 having the antenna 38 and the high-frequency voltage source 39 is sandwiched and held between the lower front case 34 and the lower rear case 35, and the lower front case 34 and the lower rear case 35 are combined to carry. The lower housing of the terminal is assembled, and the lower housing and the upper housing are connected by a hinge or the like to form a two-foldable mobile terminal that can be opened and closed.

In the second embodiment, the upper circuit board 33 has the ring-shaped conductor 18 and the screw insertion hole 19 shown in FIG. 2 as in the case of the circuit board 13 according to the first embodiment.
The inductor 21 is provided as high-frequency insulating means, and the pedestal 17 in FIG. 2 is provided on the inner bottom of the upper front case 31. The pedestal 17 is provided with the metal screw 20 through the screw insertion hole 19. The upper circuit board 33 is configured to be fastened and fixed.

Next, the operation will be described. A high frequency current is excited on the antenna 38 by the high frequency voltage source 39, and the high frequency current is applied to the ground 36 of the lower circuit board 36.
The point induced by a is the same as in the case of the first embodiment. However, in the case of the two-fold type portable terminal according to the second embodiment, the ground 3 of the upper circuit board 33 is
A high frequency current is also induced in 3a.

Here, the antenna 38 is the lower circuit board 36.
Ground 36a of the ground conductor of the upper circuit board 33
Is connected to the ground conductor, that is, the ground 36a of the lower circuit board 36 by the linear conductor bundle 37, so that the operating frequency of the antenna 38 that allows the ground 33a of the upper circuit board 33 to be seen from the ground 36a of the lower circuit board 36. When the wavelength becomes larger than about 1/4 of the wavelength at, the ground 33a of the upper circuit board 33 operates as a non-excitation element, and a large high frequency current is induced there. Therefore, even in the upper housing to which the antenna 38 is not directly connected, the antenna efficiency may deteriorate due to the factors described in the first embodiment.

However, according to the second embodiment, the ring-shaped conductor 18, the screw insertion hole 19 and the inductor 21 shown in FIG. 2 are provided on the upper circuit board 33 as the high frequency insulating means. The upper front case 31 and the ground 33a of the upper circuit board 33 in the body can be high-frequency insulated (insulated from high-frequency current on the ground 33a of the upper circuit board 33). Therefore,
Even in the case of the two-folded type mobile terminal, it is possible to prevent deterioration of the antenna efficiency as in the case of the first embodiment, and at the same time, the configuration is simple and the cost increase can be suppressed.

Embodiment 3. In the first embodiment, the antenna 15 is a portable terminal with a built-in antenna provided on the rear case 12 side with respect to the ground 14 of the circuit board 13. Therefore, the front case 11 is provided so as not to interfere with the radiation of the antenna 15. Although the metal material and the rear case 12 are made of the dielectric material, the antenna 15 does not necessarily have to be the built-in type, and may be a projecting antenna that can be pulled out and stored. In this case, the same effect can be obtained. In that case, the rear case 12 may be made of a metal material and the front case 11 may be made of a dielectric material. In the second embodiment, only the upper front case 31, which is a part of the upper housing of the mobile terminal, is made of a metal material, but a metal case may be used as a part of the lower housing. Even if there is, it is possible to prevent the efficiency deterioration of the antenna by taking the same high frequency insulation measures. The same effect can be obtained even if both the upper and lower casings are metal cases.

[0033]

As described above, according to the present invention, between the conductive case and the ground conductor of the circuit board, the insulating means against the high frequency current for operating the antenna connected to the ground conductor is provided. Since the structure is provided, there is an effect that it is possible to prevent the efficiency deterioration of the antenna due to the high frequency current flowing on the ground conductor.

According to the present invention, a plurality of circuit boards having ground conductors, a linear conductor bundle connected between these circuit boards, one or more cases having conductivity, and the ground conductor The portable terminal is, for example, a two-fold type, because it is provided with an antenna connected thereto, and an insulating means against a high frequency current for operating the antenna is provided between the case and the ground conductor of the circuit board. However, there is an effect that the efficiency deterioration of the antenna due to the high frequency current can be prevented.

According to the present invention, since the insulating means electrically insulated from the ground conductor of the circuit board is provided in the conductive portion between the case and the circuit board, the structure is simple and the cost is increased. The effect is that it can be suppressed.

According to the present invention, the conducting portion between the case and the circuit board is connected to the ground conductor of the circuit substrate by an inductor, so that the conducting portion between the case and the circuit board is on the ground conductor. The high frequency current can be cut off by the inductor, so that there is an effect that the efficiency deterioration of the antenna can be prevented.

According to the present invention, since the antenna is arranged in the gap formed by the plurality of circuit boards, there is an effect that the portable terminal can be downsized and simplified.

According to the present invention, since the case is made of the magnesium alloy, the weight of the portable terminal can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view showing an antenna device for a mobile terminal according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a state in which a high-frequency insulating unit is provided in the mobile terminal antenna device of FIG.

FIG. 3 is a schematic exploded perspective view showing an antenna device for a mobile terminal according to a second embodiment of the present invention.

FIG. 4 is a schematic exploded perspective view showing a conventional mobile terminal antenna device.

[Explanation of symbols]

1 Metal front case, 1a Contact connection part, 2
Circuit board, 3 resin rear case, 4 contacts, 5
Antenna feed point, 6 ground plane, 7 antenna, 8
Antenna mounting hole, 11 front case, 12 rear case, 13 circuit board, 14 ground (ground conductor), 1
5 antenna, 16 high frequency voltage source, 17 pedestal, 18
Ring-shaped conductor, 19 screw insertion hole, 20 screw, 21
Inductor, 31 upper front case, 32 upper rear case, 33 upper circuit board, 33a ground,
34 lower front case, 35 lower rear case, 3
6 lower circuit board, 36a ground, 37 linear conductor bundle, 38 antenna, 39 high frequency voltage source.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Omine             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Yasuto Imanishi             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Tetsuya Tanaka             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Hideaki Tokai             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F term (reference) 5J045 AA01 AA21 AB05 DA09 HA06                       NA01                 5J047 AA04 AA07 AB13 FD01                 5K023 AA07 BB06 LL01 LL05 LL06                       QQ03

Claims (6)

[Claims] 1. An antenna device for a mobile terminal, comprising: a circuit board having a ground conductor; a case having conductivity; and an antenna connected to the ground conductor, wherein the case is provided between the case and the ground conductor of the circuit board. An antenna device for a mobile terminal, further comprising insulating means for operating a high frequency current for operating the antenna. 2. A plurality of circuit boards having ground conductors, a linear conductor bundle connected between these circuit boards, one or more cases having conductivity, and an antenna connected to the ground conductors. An antenna device for a mobile terminal, comprising: an insulating means for operating a high frequency current for operating the antenna between the case and the ground conductor of the circuit board. 3. The insulating means is provided in a conductive portion between the case and the circuit board, and is electrically insulated from a ground conductor of the circuit board. Antenna device for mobile terminals. 4. The antenna device for a mobile terminal according to claim 3, wherein the conductive portion between the case and the circuit board is connected to the ground conductor of the circuit board by an inductor. 5. The antenna device for a mobile terminal according to claim 2, wherein the antenna is arranged in a gap formed by a plurality of circuit boards. 6. The antenna device for a mobile terminal according to claim 1, wherein the case is made of a magnesium alloy.