JP2001358514A - Radio terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve characteristics of an antenna and to reduce an SAR (Specific Absorption Rate). SOLUTION: A radio terminal device comprises first and second flipper antenna elements 3Fa and 3Fb formed in an electrically same length and provided at a flipper 15 openably and closably mounted at a lower part of a body, and a balanced-to-unbalanced transforming means (balun 20) provided between the first and second flipper antenna elements and an unbalanced transmission line. When the flipper is opened, the first and second antenna elements are connected to a transmitter-receiver circuit system to function as the antenna, while when the flipper is closed, the antenna elements projected from the upper part of the body are connected to the transmitter-receiver circuit system to function as the antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless terminal device such as a portable telephone device.

[0002]

2. Description of the Related Art FIG. 24 shows an example of a mobile radio communication terminal.
(A) and (b) show a mobile phone device. FIG. 24A shows an antenna 101 protruding from an upper portion of a main body 100. Similarly, FIG.
Are provided so as to protrude, and a flipper 103 which can be opened and closed is provided below the main body 100. The flipper 103 is formed of a non-metallic material and functions as a lid that covers and protects, for example, a keypad, and is opened during a call as illustrated.

[0003] As shown in these figures, an antenna 101 is usually provided so as to protrude from an upper part of a main body of a terminal, and an element used as an element is formed by winding a conductive linear element in a coil shape. Generally, it is a so-called helical antenna. This protruding antenna 1
In some cases, 01 can be pulled out by pulling it in the longitudinal direction of the terminal so that a stable call state can be maintained during a call. In this case, the extracted linear antenna element, a so-called rod antenna element, operates as an antenna, or a composite antenna of the aforementioned helical antenna element disposed inside the rod and the extracted rod antenna element. Operate as an antenna.

In recent years, with the rapid growth of the mobile phone market, base stations of mobile phone systems have been improved, and the number of places where stable communication can be maintained without having to pull out the antenna 101 has been increasing. The number of terminals in which the protruding antenna 101 is a so-called fixed type antenna that is not capable of being pulled out is increasing. The fixed type antenna has a simpler structure than the drawer type antenna, so the manufacturing cost can be reduced.
Particularly in the European market, portable radio terminals employing this fixed antenna have become popular.

[0005] The antenna in such a conventional mobile radio communication terminal includes a protruding antenna element 101.
However, whether it is a fixed type or a telescopic type that can be stored and pulled out inside and outside the terminal, the one that is supplied directly from an unbalanced transmission line such as a coaxial cable via a matching circuit for impedance matching Lord. In any case, as shown in FIG. 24C, a ground 104 having substantially the same size as the portable wireless terminal exists for the antenna element 101 protruding from the housing.

[0006]

FIG. 26 shows such an excitation mode of the antenna. As shown in FIG. 26 (a), first and second antenna elements 220 and 220, which are structurally and electrically symmetrical like a dipole antenna,
The antenna composed of the first and second antennas 221 operates by generating voltages having the same amplitude in the first and second antenna elements 220 and 221 and being out of phase by about 180 degrees with each other, thereby achieving a balanced excitation mode. Therefore, it is classified as a balanced antenna.

As shown in FIG. 26 (c), for example, an object arranged almost vertically on a ground member which can be regarded as being infinite and infinitely larger than a disk having a radius of one wavelength (electric length). A ground member 222 that is structurally asymmetric and can be regarded as infinite, such as a pole antenna,
Antenna element 223 arranged almost perpendicular to this
This vast ground member 22
2 has a substantially zero potential, and a voltage that changes in a predetermined cycle is generated in the antenna element 223 to operate and take an unbalanced excitation state. Therefore, the antenna element 223 is classified as an unbalanced antenna.
In such an unbalanced antenna, an image current flowing through the unbalanced antenna can be easily assumed by having the vast ground member 222, and the antenna characteristics of the unbalanced antenna are different from those of the balanced antenna. They can be selected almost equally.

However, in the antenna configuration of the portable telephone device as shown in FIG. 24, when the ground 104 does not fulfill the original proper function as the ground, and the protruding antenna element 101 is the first antenna element, the ground 104 operates as a second antenna element, and as a whole, an asymmetric dipole composed of the first and second antenna elements and having an intermediate excitation form that cannot be balanced or unbalanced In other words, it functions as an antenna. For example, FIG.
As shown in FIG. 6 (b), the first and second antenna elements 224 and 225, which are structurally and electrically asymmetric, cause an imbalance in current due to the difference in the excitation mode, and a balanced excitation mode. Since they take an intermediate excitation state that cannot be taken as an unbalanced excitation state, they are classified as antennas different from the balanced antenna and the unbalanced antenna (hereinafter, referred to as antennas in the intermediate excitation state).

Here, as shown in FIG. 27, a model of an antenna configuration in which a transmission / reception circuit 231 and balanced antenna elements 220 and 221 are connected by an unbalanced transmission line 232 such as a microstrip line is considered. In this manner, in the antenna configuration, basically, one of the antenna elements 220 of the balanced antenna is connected to the unbalanced transmission line 232.
And the other antenna element 221 is electrically connected to the transmission / reception circuit 231 via the ground side 234 of the unbalanced transmission line 232, and is electrically connected to the transmission / reception circuit 231 via the hot side 233. It is grounded via the side 234 to the shield case (that is, the ground 104 in FIG. 24C).

In this antenna configuration, however, the antenna elements 220 and 221 assume a balanced excitation mode, whereas the unbalanced transmission line 232 assumes an unbalanced excitation mode due to the grounding of the ground side 234. Since the antenna elements 220 and 221 and the unbalanced transmission line 232 are directly electrically connected to each other, when the antenna elements 220 and 221 operate as antennas, a current is generated due to a difference in the excitation state. Unbalance occurs. As a result, the antenna element 22
1 through a ground side 234 of the unbalanced transmission line 232, a leakage current i2 flows to a shield case (ground 104) having substantially the same potential as the ground side 234, and the shield case (ground 104)
2 operates as an antenna.

In the portable telephone device as shown in FIG. 23, the ground 104 operates as an antenna element, and the intermediate excitation state as shown in FIG. 26B is caused by the leakage current i2. is there.

As can be understood from the above, FIG.
In the conventional portable wireless terminal antenna configuration as described above, the second antenna element, which is relatively large, that is, the shield case serving as the ground 104 is covered with the hand when the user holds the terminal with the hand. Will be. As a result, there is a problem that the antenna characteristics and the communication quality are significantly deteriorated.

FIGS. 25A and 25B show FIGS.
(B) shows the state of each mobile terminal device during a call. During a call, not only the protruding antenna element 101 but also the ground 1 which is a relatively large second antenna element.
04 also approaches the human head (distance DH). This not only causes deterioration of antenna characteristics and communication quality, but also SAR (Specific Absorption).
Rate: It is undeniable that the suppression of power (power per unit time / unit mass absorbed by a specific part of the human body) is disadvantageous (it is less than the upper limit value but approaches the upper limit value).

[0014]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention improves the antenna characteristics and communication quality, and improves the SAR performance.
It aims at realizing reduction of.

[0015] For this reason, a wireless terminal device for mobile communication according to the present invention comprises a flipper mounted on the lower part of the main body so as to be openable and closable, a first flipper antenna element formed on the flipper, and A second flipper antenna element having the same length as the first flipper antenna element;
, An unbalanced transmission line for feeding power to the first and second flipper antenna elements, and an unbalanced transmission line between the unbalanced transmission line and the first and second flipper antenna elements. And equilibrium-unbalance conversion means for performing a balance conversion operation.

In addition to the above configuration, furthermore, a protruding antenna element protruding from an upper portion of the main body, and a switch for selectively connecting the protruding antenna element and the first and second flipper antenna elements to a transmission / reception circuit system. Means, detecting means for detecting the open / close state of the flipper, and when the detecting means detects that the flipper is open, the first and second flipper antenna elements are connected to the transmission / reception circuit system. Switching control means for controlling the switching means so that the protruding antenna element is connected to the transmitting and receiving circuit system when the detecting means detects that the flipper is closed. Prepare. Further, the balance-unbalance conversion means is arranged near the tip of the flipper.

That is, in the present invention, a balun (balanced-to-balanced) is provided between the unbalanced transmission line 32 and the flipper antenna means provided on the flipper which is a lid which can be opened and closed at the bottom of the main body. -unbalanced trans
a leakage current from the flipper antenna means to the ground side of the unbalanced transmission line, and the shield case (ground) operates as an antenna due to the leakage current. To prevent In addition, by using flipper antenna means provided on a flipper which is relatively far from the user's head during use, SAR can be reduced and antenna characteristics can be improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a portable telephone device will be described as an embodiment of a wireless terminal device of the present invention, and the description will be made in the following order. 1. 1. First embodiment Second embodiment3. 3. Configuration example of flipper antenna element that can be used in each embodiment 4. Configuration example of balun that can be adopted in each embodiment Connection configuration example of balun and matching circuit that can be adopted in each embodiment

1. First Embodiment FIGS. 1A, 2A, and 2B show examples of the appearance of a mobile phone device according to a first embodiment. This mobile phone device has a flipper 15 which is a lid that can be opened and closed at the bottom of the main body. FIG. 2A shows a state in which the flipper 15 is opened, and FIG. 2B shows a state in which the flipper 15 is closed. (Folded)
Each state is shown in a perspective view. The flipper is made of a non-metallic material, and for example, can be pivoted for opening and closing by being pivotally attached to one end of the main body.

As shown in FIGS. 1A and 2, a display unit 9 made of, for example, a liquid crystal panel is formed on the plane of the main body of the portable telephone device. For example, an operation menu,
Calling phone number, incoming phone number and name of the other party, reception status, e-mail text, service menu,
Characters and images of receivable data services, character images, screen saver images, and the like can be displayed.

An operation unit 10 using various operation keys for user operation is provided on the plane of the main body. In addition,
Although an operation key such as a push dial is shown here, a jog dial, a slide switch, and the like, which can be rotated and pressed, may be provided. The operation unit 10 allows the user to perform various operations for telephone calls, menu operations, selection operations, input operations of characters and the like, and various other necessary operations. The operation unit 10 does not appear when the flipper 15 is closed as shown in FIG. 2B. As a result, protection of the operation keys during carrying and prevention of erroneous operations (such as accidental pressing of keys) are performed. The loudspeaker 7 and the microphone 8 are input / output portions for voice during a call.

On the flipper 15, there are provided flipper-mounted antenna elements (hereinafter referred to as flipper antenna elements) 3Fa and 3Fb. The flipper antenna elements 3Fa and 3Fb are, for example, flippers 15
It is formed of a conductive material of a size and thickness that can be mounted on the top. And each flipper antenna element 3Fa,
3Fb has the same electrical length and a symmetric structure. The flipper antenna elements 3Fa and 3Fb are respectively connected to two terminals on the balanced side of the balun 20, and are connected via the balun 20 to a transmission / reception circuit provided inside the portable telephone device main body. It has a structure in which it is electrically connected to a transmission line (described later) and is supplied with power.

Although FIGS. 1 and 2 show an example in which the balun 20 is mounted on the flipper 15, the balun 20 may be installed inside the portable telephone device body.

FIG. 1B schematically shows the structure of the ground 14 in the main body. The ground 14 has the same potential as the ground of the unbalanced high-frequency transmission line, and refers to a conductor block contained in the main body of the mobile phone device. Usually, this is a shield case that covers a circuit board on which circuit elements of a mobile phone device are mounted.

FIG. 3 shows the internal configuration of the portable telephone device. As shown, the CPU 1, the memory 2, the flipper antenna elements 3Fa and 3Fb, the transmission / reception circuit 4, the baseband processing unit 5, the audio unit 6, the speaker 7, the microphone 8,
The display unit 9, the operation unit 10, and the balun 20 are electrically connected. Note that a matching circuit (13F) for impedance adjustment is provided between the transmitting / receiving circuit 4 and the flipper antenna elements 3Fa and 3Fb, but is omitted in FIG. 3 and will be described later with reference to FIG.

The CPU 1 is a part that performs overall control of the operation of the portable telephone device, that is, voice communication operation, packet communication operation, storage, management, user operation, display operation, and the like of various information. The memory 2 comprehensively indicates a storage area provided in the mobile phone device, such as a ROM, a flash memory, or a D-RAM, and stores / reads information under the control of the CPU 1. The memory 2 is used, for example, for storing operation programs for the CPU 1 to perform various controls, coefficients and set values used for processing, and as a work area for the CPU 1. In addition, storage of information captured by packet communication and storage of telephone numbers registered by the user are also performed.

As shown in FIGS. 1 and 2, the operation unit 10 is the above-mentioned operation key provided on the main body of the portable telephone device and used for user operation. The search information is supplied to the CPU 1. The CPU 1 executes a required control operation according to a user's operation using the operation unit 10. The user can also input character information for message input or dial registration by operating the operation unit 10, and the CPU 1 performs transmission processing and storage processing for the input character information in the memory 2. The display unit 9 is formed of, for example, a liquid crystal panel as described with reference to FIGS. 1 and 2, and presents various kinds of information to the user based on the control of the CPU 1.

Flipper antenna elements 3Fa, 3F
b, the balun 20 (and the matching circuit 13F, not shown), the transmission / reception circuit 4, the baseband processing unit 5, and the audio unit 6 execute communication processing during a call or packet communication. In the transmission / reception circuit unit 4, in the reception circuit system, reception / demodulation processing at a selected required frequency and the TDMA method (Time
Division Multiplex Access) to obtain a baseband signal. That is, at the time of reception, amplification is performed on the radio signal received by the flipper antenna elements 3Fa and 3Fb, reception / demodulation processing on a required frequency channel, TDMA decoding and the like are performed, and demodulation is performed as a baseband signal. 5

Further, the transmission circuit system in the transmission / reception circuit 4 performs processing such as encoding, transmission modulation, and amplification in the TDMA system. That is, at the time of transmission, the signal supplied from the baseband processing unit 5 is subjected to TDMA encoding and modulation processing using a required frequency, and the transmission signal is amplified, so that the flipper antenna elements 3Fa and 3F
From b, radio wave transmission output is performed.

The baseband processing unit 5 performs predetermined signal processing on a signal demodulated to a baseband signal by the transmission / reception circuit 4 at the time of reception. A signal decoded by the baseband processing unit 5 during a voice call is supplied to the voice unit 6 and output from the speaker 7. Microphone 8
Is supplied to the baseband processing unit 5 through the processing of the audio unit 6, subjected to predetermined signal processing, and further processed and transmitted by the transmission / reception circuit 4. At the time of packet communication, the received packet data is supplied to the CPU 1 via the baseband processing unit 5, stored in the memory 2, or displayed on the display unit 9.

FIG. 4 shows a transmitting / receiving circuit 4 via a balun 20.
And the connection state of the flip-flop antenna elements 3Fa and 3Fb (the matching circuit 13F is omitted).

In this example, the flipper antenna elements 3Fa and 3Fb have the same electrical length and a symmetric structure, and function as a balanced antenna. As described in FIG. 27, when an unbalanced high-frequency transmission line such as a coaxial cable or a microstrip line is directly connected to a balanced antenna, a leakage current i2 flows to the unbalanced high-frequency transmission line side. An unbalanced high-frequency transmission line also radiates radio waves like an antenna, and a ground portion operates as an antenna element. In order to prevent the generation of the leakage current i2, a balanced / unbalanced conversion circuit inserted between the unbalanced high-frequency transmission line and the balanced antenna has a balun (balun: bala).
nced-to-unbalanced transformer) 20.

Therefore, as shown in FIG. 4, a balun 20 for performing a balance-unbalance conversion operation is provided between the unbalanced transmission line 19 (hot side 17 and ground side 18) and the flipper antenna elements 3Fa and 3Fb. The balun 20 converts the unbalanced state into a flipper antenna element 3.
The leakage current i2 is prevented from flowing from Fb to the ground side 18 of the unbalanced transmission line 32, thus preventing the ground 14 (shield case) shown in FIG. 1B from operating as an antenna due to the leakage current i2. The specific structure of the balun 20 will be described later.

As described above, in this example, the two flipper antenna elements 3Fa and 3Fb are electrically the same length and symmetric in structure, and are unbalanced high-frequency transmission lines 19
And a balun 20, and the balance / unbalance conversion is performed, so that the excited state is almost the same as the balanced antenna shown in FIG. 26A, that is, the dipole antenna. Since the balanced-unbalanced conversion is reliably performed by the balun 20, there is no leakage current to the unbalanced side, that is, the high-frequency transmission line 19 side, and the balanced type flipper operates as an antenna. Only the antenna elements 3Fa and 3Fb are provided. That is, ground 1
4 does not work as an antenna.

Therefore, as shown in FIG. 5, when the user talks while holding the main body in his hand, the ground 14 as a shield case does not become an antenna, so that the antenna element is covered with the user's hand or the head is Will not be near. Further, the flipper 15 is a part that is not normally held by the hand, and the flipper antenna elements 3Fa and 3Fb functioning as antennas are not covered with the hand. As a result, in this example, even during a call (in the state of being close to a human body), the antenna characteristics are improved, and an improvement in call quality can be realized.
Further, as shown as a distance DF in FIG.
(Flipper antenna elements 3Fa, 3Fb) are the parts farthest from the user's head. Therefore, the SAR can be kept low.

2. Second Embodiment Next, the configuration and operation of a mobile phone device according to a second embodiment of the present invention will be described. FIGS. 6A and 6B
FIG. 2 is a perspective view showing the appearance of the mobile phone device according to the second embodiment, with the flipper 15 opened and closed. Also in this example, the flipper antenna elements 3Fa and 3Fb having the same length and a symmetrical structure are provided on the flipper 15 which can be opened and closed by a non-metallic material, and power is supplied via the balun 20. This is the same as in the first embodiment. In this example, an antenna element 3T is provided as an antenna protruding above the main body. The protruding antenna element 3T is a so-called helical antenna in which a conductive linear element is wound in a coil shape. In this example, the fixed antenna has a simple structure and a low manufacturing cost as compared with the rod antenna. The display unit 9 using a liquid crystal panel, the operation unit 10 using various operation keys, the speaker 7, and the microphone 8 are provided in the same manner as in the first embodiment. Also in this case, the ground 14 is formed by a shield case or the like in the main body housing as shown in FIG.

FIG. 7 shows the internal configuration of the portable telephone device. As shown, CPU 1, memory 2, projecting antenna element 3T, flipper antenna elements 3Fa, 3F
b, transmission / reception circuit 4, baseband processing unit 5, audio unit 6,
Speaker 7, microphone 8, display unit 9, operation unit 10,
Each part of the open / close detection unit 11, the switching circuit 12, the matching circuit 13T, and the balun 20 is electrically connected. A matching circuit 13F is arranged between the flipper antenna elements 3Fa and 3Fb and the transmitting / receiving circuit 4, but is omitted here as in the case of FIG. 3 and will be described later with reference to FIG.

The CPU 1, the memory 2, the flipper antenna elements 3Fa and 3Fb, the transmission / reception circuit 4, the baseband processing section 5, the audio section 6, the speaker 7, the microphone 8, the display section 9, the operation section 10, and the balun 20 are basically described. Is the same as in FIG. 3 and the description is omitted.

In this case, the projecting antenna element 3T
And the flipper antenna elements 3Fa and 3Fb are selectively connected to the transmission / reception circuit 4 by the switching circuit 12,
When each is connected to the transmission / reception circuit 4, it functions as an antenna.

The open / close detector 11 detects the open / closed state of the flipper 15. Various concrete configurations are conceivable, and various examples are conceivable, such as a configuration in which a mechanical switch is turned on / off in accordance with the rotation of the flipper 15, and a configuration in which a reflection-type optical sensor or the like optically detects. Information detected by the open / close detector 11 is supplied to the CPU 1. The CPU 1 controls the switch connection state of the switching circuit 12 according to the open state and the closed state of the flipper.

FIG. 8 schematically shows a system from the projecting antenna element 3T, the flipper antenna elements 3Fa and 3Fb to the transmitting / receiving circuit 4. The protruding antenna element 3T is connectable to the transmission / reception circuit 4 via the matching circuit 13T, the high-frequency transmission line 16, and the switching circuit 12. The flipper antenna elements 3Fa and 3Fb can be connected to the transmission / reception circuit 4 via the balun 20 (and the matching circuit 13F not shown), the unbalanced high-frequency transmission line 19, and the switching circuit 12. Therefore, the projecting antenna element 3T and the flipper antenna elements 3Fa, 3Fb
In both cases, depending on the switch connection state of the switching circuit 12,
It can function as a transmitting and receiving antenna.

As shown, the switching circuit 12 has a terminal t.
A switch having 1 and t2 is provided. And C
When the connection terminal is selected at the terminals t1 and t2 by the PU1, the protruding antenna element 3T and one of the flipper antenna elements 3Fa and 3Fb are selected as functioning antennas. Specifically, CPU
1 connects the t2 terminal of the switching circuit 12 during a period in which the flipper 15 is detected as being opened by the opening / closing detection unit 11, for example, during a call, so that the flipper antenna elements 3Fa and 3Fb are used as antennas. Let it work. On the other hand, the CPU 1 connects the t1 terminal of the switching circuit 12 during the period in which the flipper 15 is detected to be closed by the open / close detection unit 11, for example, in a standby period, so that the protruding antenna element 3T is used as an antenna. Let it work.

In the second embodiment, the following effects can be obtained. First, when the flipper 15 is opened, that is, when the user is talking, the flipper antenna elements 3Fa and 3Fb function as antennas. FIG. 9 shows a state during a call. The distance DH between the protruding antenna element 3T and the user's head, the flipper antenna elements 3Fa and 3Fb are shown.
The distance DF between the user and the user's head is DF> DH. Therefore, the flipper antenna elements 3Fa, 3Fb
Is used to reduce the value of SAR. Further, the flipper antenna element 3Fa,
3Fb is the balun 2 as in the case of the first embodiment.
0, and are connected via an unbalanced high-frequency transmission line 19 as shown in FIG. Therefore, as in the case of the first embodiment, the leakage current is prevented, and the ground 14 does not function as an antenna, so that an improvement in antenna characteristics and an improvement in communication quality can be realized.

On the other hand, when the flipper 15 is closed,
That is, when the user has the mobile phone device in his bag or pocket (at standby), the protruding antenna element 3T functions as an antenna. In this case, since the mobile phone device is not close to the user's head, there is no problem in terms of SAR even if the protruding antenna element 3T is used.

Further, when the flipper 15 is closed, the flipper antenna elements 3Fa and 3Fb come close to the ground portion of the main body, so that the antenna characteristics may be slightly deteriorated depending on the frequency band used. However, this is not a problem because the projecting antenna element 3T is used. The protruding antenna element 3T does not have very good antenna characteristics near the human body, but does not pose a problem since it functions as an antenna when the mobile phone is in a standby state away from the human body.

The switching operation of the switching circuit 12 may be manually selected by the user. For example, it is also possible to provide a dedicated switching key or switch in advance so that the user can switch over himself or herself, and to operate the key or switch to perform electrical or mechanical control. Although the switching operation of the switching circuit 12 is controlled by the CPU 1, a switching mechanism that mechanically switches according to the opening and closing of the flipper 15, for example, may be formed. That is, the switch mechanism has a flipper open / close detection and switching control function.

3. Configuration example of flipper antenna element that can be adopted in each embodiment By the way, flipper antenna elements 3Fa and 3Fb
Various examples other than the shapes shown in the above embodiments are possible. 10 to 13, examples of various flipper antenna elements 3Fa and 3Fb will be described.

The flipper antenna elements 3Fa and 3Fb shown in FIG. 1, FIG. 2 and FIG.
Is formed on the inside of the flipper 15 (the surface facing the operation unit 15 of the main body) so as to be hidden from the outside when folded, but is formed on the outer surface side of the flipper. You may. Furthermore, a pattern as flipper antenna elements 3Fa and 3Fb may be formed inside flipper 15 so that contact with the outside is completely cut off. In each of the examples described below, these modifications can be considered.
Further, the two flipper antenna elements 3Fa and 3Fb mounted on the flipper 15 are of the same electrical length, and may be any conductive element having a size and thickness that can be mounted on the flipper portion.

FIG. 10 shows that the unbalanced high-frequency transmission line 19 coming from the internal transmission / reception circuit 4 extends to the tip of the flipper 15, and has the same electrical length and symmetrical structure from the center of the tip of the flipper 15. In this example, two flipper antenna elements 3Fa and 3Fb are supplied with power via a balun 20. According to this configuration, since the unbalanced high-frequency transmission line 19 is elongated, the loss is increased accordingly, but the SAR is more advantageous. This is because the maximum point of the current distribution in the dipole antenna is near the feeder, and the SAR
This hot point is also here, but with this configuration,
The hot point is located at the tip of the flipper 15 (near the balun 20), and this tip is usually the most distant from the human body during a call.
This is because AR reduction can be achieved.

FIGS. 11A, 11B and 11C show examples of patterns as flipper antenna elements 3Fa and 3Fb. Depending on the used frequency band, it may not be sufficient to simply make the length of the antenna element straight on the flipper 15. That is, the lower the frequency band of the system,
It is required to increase the antenna element length. In this case, as shown in FIG. 11A, each of the flipper antenna elements 3Fa and 3Fb may have a meander line shape to increase the element length. Or FIG.
Each flipper antenna element 3Fa as shown in FIG.
3Fb may be formed as a zigzag line in a V-shape to increase the element length. Further, as shown in FIG. 11C, the length of the antenna element is increased by forming each flipper antenna element 3Fa, 3Fb as a zigzag line that alternately appears on the front surface and the rear surface of the flipper 15 through the through hole TH. It is possible

FIG. 12 shows that each of the flipper antenna elements 3Fa and 3Fb is linearly formed along the end of the flipper 15 on the main body side, and then is formed in a meander line shape along the side end of the flipper 15 so that the antenna is formed. This is to increase the element length. FIG. 13 shows that after extending the unbalanced high-frequency transmission line 19 to the tip of the flipper 15 as shown in FIG. 10, the flipper antenna elements 3Fa and 3Fb connected via the balun 20 are attached to the tip of the flipper 15. Then, the antenna element length is increased by forming a straight line along the side edge of the flipper 15 and then forming a meander line along the side end.

With the configuration shown in FIGS. 11 to 13, regardless of the size and shape of the flipper 15,
The required antenna element length can be ensured, and the transmission and reception characteristics of the flipper antenna elements 3Fa and 3Fb can be improved. Although various examples of the flipper antenna element 3F have been described, it is needless to say that various other patterns can be considered as the pattern of the flipper antenna element 3F. For example, in the examples of FIGS. 12 and 13, the meandering portion may be shaped as shown in FIGS. 11B and 11C, or the shapes of FIGS. 11A, 11B, and 11C may be combined.

4. Configuration example of balun that can be adopted in each embodiment Subsequently, the balun 20 described in the first and second embodiments is used.
Various examples will be described as specific configuration examples.

FIGS. 14 to 16 show a balun 20 in which the phase of two terminals on the balanced side is shifted by 180 ° to suppress the leakage current to the unbalanced side, which is called a conversion type balun. It is.

FIG. 14 shows that the phase shift of 180 ° is shifted by λ /
This is a balun with a λ / 2 detour, in which a line having an electrical length of 2 is realized by a coaxial cable 22. That is, one end of the hot side 22a of the coaxial cable (detour path) 22 having an electrical length of 波長 wavelength at the used frequency is electrically connected to one end of the hot side 17 of the unbalanced transmission line 19 formed of the coaxial cable 21. At the same time, one end of the ground side 18 of the unbalanced transmission line 19 is
b is electrically connected at one end. In the balun 20 having such a configuration, a flipper antenna element 3Fa as a substantially balanced antenna is electrically connected to one end of the hot side 17 of the unbalanced transmission line 19, and the hot side 22a of the bypass line 22 is electrically connected. The other end is electrically connected to a flipper antenna element 3Fb.
The high-frequency signal to be transmitted to the flipper antenna element 3Fa via the hot side 17 of the unbalanced transmission line 19 is shifted by about 180 degrees with respect to the flipper antenna element 3Fa via the hot side 22a of the detour path 22 so as to be flipped. Also sent to antenna element 3Fb,
This prevents leakage current from flowing from the flipper antenna element 3Fb to the ground side 18 of the unbalanced transmission line 19.

FIG. 15A shows a case where the above-mentioned 180 ° phase shift is constituted by a π-type or T-type phase shift circuit 23 having a symmetric structure as shown in FIGS. 15B to 15E. The inductive reactance element (inductor) L and the capacitive reactance element (capacitor) C1, which are components of the phase shift circuit 23, are 18
The constant is determined such that the phase shifts by 0 °. As shown in FIG. 15A, the balun 20 branches one end of the hot side 17 of the unbalanced transmission line 19 into two systems, and the one of the branched transmission lines has the flipper antenna element 3.
Fa is electrically connected to the other transmission line and the flipper antenna element 3F via the phase shift circuit 23.
b is electrically connected. Here, in the phase shift circuit 23, for example, as shown in FIG. 15B, two inductive reactance elements L1 and L2 are connected in series, and one end of the capacitive reactance element C1 is conductively connected to a connection point P1. In addition, a plurality of T-type phase shift circuits having a symmetric structure in which the other end of the capacitive reactance element C1 is grounded to a ground (shield case) is configured. The phase shift circuit 23 shifts the phase of the high-frequency signal supplied from the transmission / reception circuit 4 via the hot side 17 of the unbalanced transmission line 19 by about 180 degrees in the used frequency band, and the flip-flop antenna elements 3Fa, It will be sent to 3Fb. As a result, from the flipper antenna element 3Fb to the ground side 1 of the unbalanced transmission line 19
8 prevents leakage current from flowing.

Further, as shown in FIG. 15C, the phase shift circuit 23 connects two capacitive reactance elements C2 and C3 in series, and electrically connects one end of the inductive reactance element L3 to a connection midpoint P2. 15 and a combination of a plurality of T-type phase shift circuits having a symmetric structure in which the other end of the inductive reactance element L3 is grounded.
As shown in (d), one ends of the capacitive reactance elements C4 and C5 are electrically connected to one end and the other end of the inductive reactance element L4, respectively, and the other ends of the capacitive reactance elements C4 and C5 are grounded. 15 (e), one end and the other end of the capacitive reactance element C6 are provided with inductive reactance elements L5 and L6, respectively, as shown in FIG. It may be configured by combining a plurality of symmetric π-type phase shift circuits having one ends conductively connected and the other ends of the inductive reactance elements L5 and L6 grounded. In other words, the circuit configuration is not limited as long as the phase of the high-frequency signal can be shifted by about 180 degrees in the used frequency band.

The balun 20 in FIG. 16 is called an LC bridge balun. In this case, the first and second inductive reactance elements L7 and L8 and the first and second
And the capacitive reactance elements C7 and C8 are sequentially and alternately connected in a ring shape, and the hot side of the unbalanced transmission line is connected to a middle point P6 between the first inductive reactance element L7 and the second capacitive reactance element C8. Electrical connection,
The ground side of the unbalanced transmission line is electrically connected to a connection point P3 between the first capacitive reactance element C7 and the second inductive reactance element L8. A flipper antenna element 3 is provided at a connection point P5 between the first inductive reactance element L7 and the first capacitive reactance element C7.
Fa is electrically connected, and a flipper antenna element 3Fb is electrically connected to a midpoint P4 between the second inductive reactance element L8 and the second capacitive reactance element C8.

In the balun 20 having such a configuration, the first
And the inductances L of the second inductive reactance elements L7 and L8 are set to the same value.
The capacitances C of the capacitive reactance elements C7 and C8 are set to the same value, and the inductance L and the capacitance C are set so that (2πf) ² LC = 1 L / C = Z0 · ZA By the selection, the high-frequency signal given from the hot side of the unbalanced transmission line is directly transmitted from the connection midpoint P5 to the flipper antenna element 3Fa, and this high-frequency signal is transmitted 180 degrees to the flipper antenna element 3Fa in the used frequency band. The high-frequency signal obtained by shifting the phase by about
4 to the flipper antenna element 3Fb. Note that Z0 represents the impedance between the hot side and the ground side of the unbalanced transmission line, and ZA represents the impedance of the connection midpoints P5 and P4. Further, f represents a used frequency.

By the way, in the balun 20 using the inductor L and the capacitor C as shown in FIGS. 15 and 16, the inductor L and the capacitor C are 1 mm, which are commercially available.
Since a chip having a shape of about a square can be used, and the balun can be configured to be relatively small, it is effective in view of the recent trend of miniaturization of portable radio terminals.

FIGS. 17 to 20 show a balun 20 in which the phases of two terminals on the balanced side are shifted by 180 ° using a transformer circuit.

FIG. 17 shows a transformer type in which an air-core coil 110 formed between the hot side and the ground side of the unbalanced transmission line is opposed to an air-core coil 111 formed substantially between the flipper antenna elements 3Fa and 3Fb. The balun 20. FIG. 18 shows an air-core coil 113 formed between the hot side of the unbalanced transmission line and the flipper antenna element 3Fa, and an air-core coil 114 formed between the ground side of the unbalanced transmission line and the flipper antenna element 3Fb. Is a transformer-type balun 20 facing the balun 20.

In addition to this, as shown in FIG. 19, this type of balun 20 includes an air-core coil 116 formed between the hot side of the unbalanced transmission line and the flipper antenna element 3Fa, and a balun 20 of the unbalanced transmission line. An air-core coil 117 formed between the ground side and the ground, and an air-core coil 118 formed between the ground side of the unbalanced transmission line and the flipper antenna element 3Fb;
There is also a transformer-type balun in which an air-core coil 119 formed between the hot side of the unbalanced transmission line and the ground is opposed to the balun. The transformer-type balun 20 having such a configuration is used.
, The impedance between the connection terminals of the flipper antenna elements 3Fa and 3Fb is 4 compared to the impedance Z between the hot side and the ground side of the unbalanced transmission line.
The size is about twice (4Z).

In the transformer type balun 20 shown in FIGS. 17, 18 and 19, the air-core coils 110,
111, 113, 114, 116, 117, 118, 1
19, instead of the multilayer wiring board 12 shown in FIG.
A pair of coils 124 and 125 formed by a through hole 122 and a conductor pattern 123 can also be used for 1. The transformer-type balun 20 uses a coil formed by integrating conductor patterns as described above.
As a whole, since it can be formed by a fine chip of about 1 to 3 [mm] square, similar to the above-described LC bridge balun, when considering the trend of miniaturization of the portable wireless terminal,
This is advantageous in terms of arrangement space.

FIG. 21 shows a balun with a λ / 4 branch conductor, and FIG. 22 shows a balun which is classified as a blocking balun. It is intended to be infinite.

FIG. 21 shows an unbalanced transmission line 19 composed of a coaxial cable 126. The unbalanced transmission line 19 and a conductor (branch conductor) 127 having an electrical length of １ ／ wavelength at the operating frequency are connected at the other end. The branch conductors 12
7 is electrically connected to one end of the hot side 17 of the unbalanced transmission line 19, and the other end of the branch conductor 127 is electrically connected to a portion of the unbalanced transmission line 19 facing the ground side 18. It is configured. In the balun 20 having such a configuration, a flipper antenna element 3Fa is electrically connected to the other end of the hot side 17 of the unbalanced transmission line 19, and a flipper antenna element is connected to the other end of the ground side 18 of the unbalanced transmission line 19. 3Fb is electrically connected. In this case, since the branch conductor 127 is selected to have an electrical length of １ ／ wavelength of the operating frequency, the unbalanced transmission line 19 becomes an internal conductor as a whole when viewed from the balanced side to the unbalanced side, and The conductor 127 can be regarded as a transmission line having an electrical length of 1/4 wavelength, one of which is short-circuited and one of which is short-circuited. Since the impedance becomes infinite against leakage current, the ground side of the unbalanced transmission line 19 18
To prevent a leakage current from flowing through.

FIG. 22 shows that the unbalanced transmission line 19 by the coaxial cable 127 is inserted through the cylindrical conductor 128, one end 128A of the cylindrical conductor 128 is opened, and the other end 128B is connected to the ground of the unbalanced transmission line 19. A so-called Sperrtopf balun or a Bazooka balun shorted to the side 18. In this balun 20, the flipper antenna element 3Fa is electrically connected to the hot side 17 of the unbalanced transmission line 19 on the open side (balanced side) of the cylindrical conductor 128, and the ground side of the unbalanced transmission line 19 18 is electrically connected to the flipper antenna element 3Fb, and a transmission / reception circuit is electrically connected to the hot side 17 and the ground side 18 of the unbalanced transmission line 19 on the short-circuited side (unbalanced side) of the cylindrical conductor 128. Is done. In the balun 20, since the cylindrical conductor 128 is selected to have an electrical length of 波長 wavelength of the used frequency, the unbalanced transmission line 19 becomes an internal conductor as a whole when the unbalanced side is viewed from the balanced side. Since the cylindrical conductor 128 serves as an outer conductor and one of which is short-circuited, it can be regarded as a transmission line having an electrical length of １ ／ wavelength, and the impedance becomes infinite with respect to leakage current. Leakage current can be prevented from flowing to the ground side 18 of the semiconductor device.

In the examples shown in FIGS. 21 and 22, physically, the branch conductor 127 having a length of 波長 wavelength of the operating frequency is used.
Alternatively, since the cylindrical conductor 128 is required, the size of the balun is larger than that of the baluns shown in FIGS. If so, such a blocking balun is very effective because there is almost no loss due to the balun 20.

In any case, an optimum one of the above-mentioned various baluns may be selected in consideration of the size of the portable telephone device body and the flipper 15 to be used, the allowable loss amount, and the like. The balun 20 is not limited to these examples.
As long as leakage current can be prevented from flowing to the ground side 18 of the ninth, baluns having various other configurations can be used.

5. Example of connection configuration of balun and matching circuit that can be employed in each embodiment In the description of the first and second embodiments, description of matching circuit 13F between flipper antenna elements 3Fa and 3Fb and transmitting / receiving circuit 4 is omitted. I was This matching circuit 13
F can be provided between the unbalanced transmission line 19 and the balun 20, for example, as shown in FIG.

Further, as shown in FIG.
0 and the flipper antenna elements 3Fa and 3Fb, a matching circuit 13F may be provided. Further, as shown in FIG. 23C, matching circuits 13Fa and 13Fb may be provided on both ends of the balun 20.

However, in the case of FIGS. 23 (b) and (c), if the matching circuit 13F or 13Fb on the balanced side of the balun 20 is grounded, the flipper antenna element 3Fb Leakage current generated at the ground 14 via the matching circuit 13F.
(Shield case), and as a result, the shield case operates as an antenna. Therefore, FIG.
(D) As shown in (e), an inductive reactance element connected in parallel between two transmission lines 49 and 50 that electrically connects the balanced side of the balun 20 and the flipper antenna elements 3Fa and 3Fb. It is necessary to configure the matching circuit 13F by using the L30 or the capacitive reactance element C20 so that the matching circuit 13F is not grounded. The matching circuit installed on the unbalanced side of the balun does not have such a limitation, and may have any configuration.

Although the embodiments of the present invention have been described above, the configuration and operation of the present invention are not limited to the above examples. In addition, the present invention can be widely applied not only to a mobile phone device but also to other types of communication devices and information devices as wireless terminal devices.

[0074]

As can be understood from the above description, the wireless terminal device of the present invention has first and second flipper antennas formed to have the same electrical length on a flipper mounted on the lower part of the main body so as to be openable and closable. An element is provided, and a balance-unbalance conversion means (balun) is provided between the first and second flipper antenna elements and the unbalanced transmission line. Accordingly, the first and second flipper antenna elements assume a balanced excitation state similarly to the dipole antenna, and the leakage current to the unbalanced transmission line side is eliminated by the balanced-unbalanced conversion means, whereby the ground functions as an antenna. Never. For this reason, a situation in which the user holds the wireless terminal device in his hand to cover the ground portion, or the ground portion approaches the user's head, resulting in a decrease in antenna characteristics and a deterioration in call quality. This has the effect of being eliminated. Also,
Because the flipper is the part that is farthest from the user's head during a call and is not covered with hands,
The antenna characteristics of the first and second flipper antenna means are good, and the communication quality is improved. Further, the position farthest from the user's head has an effect that SAR reduction can be realized.

Further, according to the present invention, when the flipper is opened, the first and second flipper antenna elements are connected to a transmission / reception circuit system to function as an antenna,
On the other hand, when the flipper is closed, the protruding antenna element on the upper part of the main body is connected to the transmission / reception circuit system to function as an antenna. As a result, the above effect can be obtained during a call in which the flipper is opened. In addition, while the flipper is closed, the flipper antenna means may approach the shield case as the ground of the main body, and the antenna characteristics may be degraded. Good characteristics can be maintained. Of course, during standby, the SAR is not a problem because the wireless terminal device is not approaching the user's head.

By disposing the balance-unbalance conversion means (balun) near the tip of the flipper, S
The AR hot point can be moved as far as possible from the user's head, which is effective in reducing SAR.

[Brief description of the drawings]

FIG. 1 is a front view of a mobile phone device according to a first embodiment of the present invention and an explanatory diagram of a ground.

FIG. 2 is a perspective view of the mobile phone device according to the first embodiment in a flipper open / closed state.

FIG. 3 is a block diagram of the mobile phone device according to the first embodiment.

FIG. 4 is an explanatory diagram of a connection state of a balun according to the embodiment;

FIG. 5 is an explanatory diagram when the mobile phone device of the first embodiment is used.

FIG. 6 is a perspective view of a mobile phone device according to a second embodiment of the present invention in a flipper open / closed state.

FIG. 7 is a block diagram of a mobile phone device according to a second embodiment.

FIG. 8 is an explanatory diagram of a switching configuration of an antenna element according to a second embodiment.

FIG. 9 is an explanatory diagram when the mobile phone device according to the second embodiment is used.

FIG. 10 is an explanatory diagram of an example of a flipper antenna element according to an embodiment.

FIG. 11 is an explanatory diagram of an example of a flipper antenna element according to an embodiment.

FIG. 12 is an explanatory diagram of an example of a flipper antenna element according to an embodiment.

FIG. 13 is an explanatory diagram of an example of a flipper antenna element according to an embodiment.

FIG. 14 is an explanatory diagram of a configuration example of a balun according to the embodiment;

FIG. 15 is an explanatory diagram of a configuration example of a balun according to the embodiment;

FIG. 16 is an explanatory diagram of a configuration example of a balun according to the embodiment;

FIG. 17 is an explanatory diagram of a configuration example of a balun according to an embodiment.

FIG. 18 is an explanatory diagram of a configuration example of a balun according to the embodiment;

FIG. 19 is an explanatory diagram of a configuration example of a balun according to the embodiment;

FIG. 20 is an explanatory diagram of a configuration example of a balun according to an embodiment.

FIG. 21 is an explanatory diagram of a configuration example of a balun according to an embodiment.

FIG. 22 is an explanatory diagram of a configuration example of a balun according to an embodiment.

FIG. 23 is an explanatory diagram of a connection configuration between a balun and a matching circuit according to the embodiment;

FIG. 24 is a perspective view of a conventional mobile phone device and an explanatory diagram of a ground structure.

FIG. 25 is an explanatory diagram of a usage state of a conventional mobile phone device.

FIG. 26 is an explanatory diagram of an excited state of an antenna.

FIG. 27 is an explanatory diagram of leakage current to an unbalanced transmission line.

[Explanation of symbols]

1 CPU, 2 memories, 3T projecting antenna element, 3Fa, 3Fb flipper antenna element, 4
Transmission / reception circuit, 5 baseband processing unit, 6 audio unit, 7
Speaker, 8 microphone, 9 display unit, 10 operation unit, 11 open / close detection unit, 12 switching circuit, 13T, 13F
Matching circuit, 15 flippers, 20 baluns

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 1/02 H04B 7/26 VF term (Reference) 5J047 AA03 AB07 FD01 5K023 AA07 BB06 LL05 MM03 5K027 AA11 BB03 MM04 5K067 BB04 KK01 KK17

Claims (3)

[Claims] A first flipper antenna element formed on said flipper; a first flipper antenna element formed on said flipper; and a first flipper attached to said flipper. A second flipper antenna element formed to have the same electrical length as the antenna element, an unbalanced transmission line for feeding the first and second flipper antenna elements, an unbalanced transmission line, And a balance-unbalance conversion means for performing a balance-unbalance conversion operation with the first and second flipper antenna elements. 2. A projecting antenna element protruding from an upper part of a main body, switching means for selectively connecting the projecting antenna element and the first and second flipper antenna elements to a transmission / reception circuit system, Detecting means for detecting an open / close state; and when the detecting means detects that the flipper is open, the first and second flipper antenna elements are connected to the transmitting / receiving circuit system, and Switching control means for controlling the switching means such that the projecting antenna element is connected to the transmission / reception circuit system when the flipper is detected to be closed by the means. The wireless terminal device according to claim 1, wherein: 3. The wireless terminal device according to claim 1, wherein the balance-unbalance conversion means is arranged near a tip of the flipper.