JP5260822B2 - Portable wireless terminal - Google Patents

Description

  The present invention relates to a portable wireless terminal, and more particularly to improvement of an antenna of a foldable portable wireless terminal.

  With the rapid spread of mobile phones in recent years, the subscriber capacity has become tight, so-called dual that can be used in both the 800M band and 1.5G band and in both the 800M band and 2G band. There is a need for mobile phones that support bands. On the other hand, a wide variety of shapes of mobile phones, which are portable radio terminals, are provided. As one of these mobile phones, there is a foldable mobile phone capable of increasing the size of the display (Patent Document 1). reference).

  8 and 9 show an example of such a foldable mobile phone. FIG. 8 is a perspective view of the foldable mobile phone in an open state, and is shown in a perspective view for easy understanding of the inside. As shown in FIG. 8, the foldable mobile phone includes an upper case 1 as a first case having a display unit 20 mounted on the front side 3 and a plurality of data input buttons or buttons on the front side 5. A lower casing 2 as a second casing on which a key operation section 17 including a key is mounted, and a hinge section 19 that rotatably connects the upper casing 1 and the lower casing 2 to each other. I have.

  In the figure, 4 is the back of the upper casing, 6 is the back of the lower casing, 7 is the battery, 8 is the upper casing (printed) circuit board, 9 is the lower casing (printed) circuit board, and 10 is the upper casing. A circuit unit, 11 is a lower casing circuit unit, 12 is an amender antenna, 15 is a receiver, 16 is a microphone, and 18 is an upper and lower circuit connecting unit for electrically connecting the upper and lower casing circuit boards to each other. FPC (Flexible Printed Circuit). Reference numeral 23 denotes an external interface, which is a connector used for data communication.

  In such a foldable mobile phone, at least one of the upper casing 1 and the lower casing 2 is formed by molding plastic. A metal film (not shown) is formed on the formed surface by vapor deposition or plating, but this metal film is formed so as not to reach the hinge portion 19. For this reason, the upper housing 1 including the circuit board 8 and the lower housing 2 including the circuit board 9 are maintained in an electrically insulated state so that high-frequency current does not flow between them.

  In this case, as shown in FIG. 8, the upper housing 1 and the lower housing 2 are connected by the FPC 18 for electrical connection between the circuit boards 8 and 9, but the hinge portion 19 at this time Considering the characteristics of the antenna 12 arranged in the vicinity, as shown in FIG. 9A, by adjusting the length of the FPC 18 in the hinge portion 19 (in particular, FPC is not shown in FIG. 9), The high-frequency current B flowing through the lower casing circuit board 9 and the current A flowing through the upper casing circuit board 8 can be in phase, so that these currents A and B are in phase with the current C flowing through the antenna 12. And the efficiency of the antenna 12 is improved.

In such a foldable mobile phone, it is necessary to provide another antenna in addition to the antenna 12 in order to cope with the dual band described above, but in order to provide another antenna in addition to the antenna 12. However, it is necessary to secure another space for this purpose in the housing, but it is extremely difficult to secure such extra space in a mobile phone that is required to be reduced in size and weight.

Referring now to Patent Document 2, instead of providing another antenna, the circuit board 8 and 9 are respectively provided on upper and lower portions of the housings 1 and 2, dipole Ruantena pair of radiating elements (antennas A technique for operating as an element) is disclosed. According to this technique, since the circuit board itself is operated as an antenna element, there is an advantage that an antenna mounting space becomes unnecessary.

  As described above, in order to operate the circuit boards 8 and 9 of the upper and lower casings 1 and 2 as a pair of antenna elements of the dipole antenna, the circuit boards 8 and 9 are electrically connected to each other by the feed line. However, considering the characteristics of the antenna 12 in this case, as shown in FIG. 9B, a high-frequency current B flowing in the lower casing circuit board 9 and a current flowing in the upper casing circuit board 8 A is opposite to each other, which disturbs the current distribution of the antenna 12 and deteriorates its characteristics, making it impossible to obtain good characteristics.

Here, referring to Patent Document 3, in order to adjust the mutual coupling between antennas when two antennas are provided, there is a technique for adjusting the termination impedance of a non-selected antenna to prevent the deterioration of the characteristics of the selected antenna. It is disclosed. FIG. 10 is a diagram showing a circuit disclosed in Patent Document 3. In the case where two antennas 12 and 13 are provided, matching circuits 122 and 132 are provided for each of these antennas, and a three-terminal network T is provided. The type phase shifters 123 and 133 are provided, and the antenna selection switch 21 controls the selection of both antennas. Reference numeral 22 denotes a transmission / reception circuit common to both antennas.

  Further, referring to Patent Document 4, in a diversity antenna system for mobile communication, when one antenna is selected, a pin diode is used to electrically disconnect the power feeding terminal and the power feeding transmission line of the other antenna. A technique for preventing wasteful power consumption by preventing unnecessary high-frequency power from being supplied to a non-selected antenna using the switch circuit according to FIG.

JP 2003-008320 A JP 2004-172919 A JP 2000-286767 A JP 2000-068909 A

  In the circuit shown in FIG. 10, it is difficult to optimally adjust the terminal impedance at the same time in the mobile phone that covers both the 800M and 1.5G bands and the 800M band and the 2G band as described above. When the band is optimally adjusted, there is a problem that the other band must be used with the antenna characteristics deteriorated. In addition, the provision of the phase circuits 123 and 133 for improving the antenna characteristics increases the passage loss, thereby deteriorating the characteristics of the mobile phone.

  Furthermore, in order to improve the characteristics of the first antenna 12 provided in the vicinity of the hinge portion 19 of the foldable mobile phone shown in FIGS. 8 and 9, the upper housing circuit board 8 and the lower housing circuit board 9 are used. As described above, it is necessary to adjust the length of the FPC 18 that is the upper and lower circuit connecting portion of the phase of the antenna current of the upper casing circuit board 8 and the lower casing circuit board 9. In the case of adopting a system that constitutes the antenna 13, the upper antenna circuit board 8 and the lower chassis circuit board 9 need to be electrically connected by a feeder line. There is a problem that the characteristics of the above deteriorate significantly.

  Furthermore, in the technique of Patent Document 4, there is no idea that the second antenna is constituted by the upper casing circuit board and the lower casing circuit board in the foldable mobile phone, and this technique is equipped with two antennas. The purpose is to reduce power consumption at the time, and not to prevent the unselected antenna from adversely affecting the selected antenna.

  An object of the present invention is to provide a portable radio terminal capable of supporting a dual mode by preventing the influence of antennas when two antennas are mounted.

  Another object of the present invention is to support dual mode that can improve antenna efficiency by eliminating the factor of degrading other antenna characteristics, which is a particular problem when a circuit board is used for one of the two antennas. Is to provide a portable wireless terminal.

In the portable wireless terminal according to the present invention, in addition to the first antenna, the first and second circuit boards housed in each of the first and second housings are connected by a feed line as a second antenna. a portable wireless terminal so as to use, when the first antenna is selected, the switch means to open said second antenna, and a matching circuit for the second antenna And the switch means is provided between the feed line of the second antenna and the matching circuit, and the switch means comprises a switch circuit using a PIN diode.

  The operation of the present invention will be described. In the foldable portable wireless terminal, an antenna connection switch is provided between the feeding line of the second antenna and the matching circuit of the second antenna by the upper casing circuit board and the lower casing circuit board. When the first antenna is selected, the antenna connection switch is opened and the second antenna is not operated, so that the current distribution of the first antenna is not disturbed. Prevent characteristic deterioration.

  According to the present invention, in a foldable portable wireless terminal, there is provided an antenna system in which the upper casing circuit board and the lower casing circuit board are operated as antennas without deteriorating the characteristics of the antenna provided in the hinge portion. There is an effect that it is possible to construct. In addition, when the antenna provided in the hinge portion is covered with a hand, even if the characteristics of the antenna are deteriorated, it is possible to ensure call quality by switching to the other antenna side.

  Furthermore, according to the present invention, even in a dual-band portable wireless terminal that covers two or more different bands, it is possible to easily adjust the phase shifter to reduce the coupling between antennas, thereby reducing the passage loss. There is an effect that it becomes possible to do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an embodiment of the present invention, and the same parts as those in FIGS. In the drawing, the inside is shown in a perspective view for easy understanding.

  When the part different from FIG. 8 is described, in the present embodiment, a mobile phone is shown as a mobile wireless terminal. In this mobile phone, the first antenna 12 is mounted on the lower housing back surface portion 6 adjacent to the hinge portion 19. The antenna 12 is a meander antenna, and a feeding terminal 121 extends from the antenna 12 toward the front surface 5 of the lower housing. Further, the lower casing circuit board 9 and the upper casing circuit board 8 are connected by a feed line 131, and the lower casing circuit board 9 and the upper casing circuit board 8 are operated as a second antenna. It is configured like this.

  FIG. 2 is a diagram showing a matching circuit of the first antenna 12 and the second antenna 13, and the same parts as those in FIG. 10 are denoted by the same reference numerals. The first antenna 12 is connected to the matching circuit 122, is further connected to the antenna selection switch 21 via the phase adjustment circuit 123, and is connected to the transmission / reception circuit 22 via this switch 21.

  The second antenna 13 operates as an antenna by being fed by the feed line 131, and the feed line 131 is connected to the antenna connection switch 130, and further connected to the antenna selection switch 21 through the matching circuit 132. The switch 21 is connected to the transmission / reception circuit 21. The phase shifter 123 is adjusted so that the first antenna 12 does not operate when the second antenna 13 is selected.

  Here, the operation will be described. When the second antenna 13 is selected, the antenna selection switch 21 connects the second antenna 13 side and the transmission / reception circuit. At this time, the antenna connection switch 130 is turned on, the matching circuit 132 and the feed line 131 are connected, and the upper casing circuit board 8 and the lower casing circuit board 9 operate as the second antenna 13. At this time, the first antenna 12 is terminated by the phase shifter 123. Since the phase shifter 123 is adjusted so that the first antenna 12 does not operate when the second antenna 13 is selected, the second antenna 13 has good characteristics.

  On the other hand, when the first antenna 12 is operating, the antenna selection switch 21 selects the antenna 12 side, and the transmission / reception circuit 21 and the first antenna 12 are connected. At this time, the phase circuit 123 is adjusted so as to be 50Ω, and the matching circuit 122 is adjusted so that the impedance of the first antenna 12 can be matched with 50Ω. On the other hand, for the second antenna 13, the antenna connection switch 130 is disconnected, and the matching circuit 132 and the feed line 131 are disconnected. As a result, the second antenna 13 becomes open and does not operate as an antenna. Therefore, the operating current distribution of the first antenna 12 is not disturbed and good characteristics are obtained.

  FIG. 3 is a diagram illustrating a specific example of the circuit of FIG. 2, and is a circuit diagram in the case where the antenna connection switch 130 is configured by a PIN diode. The capacitors C1 to C4 are adjusted so that the impedance is sufficiently low at a desired frequency. Further, when the PIN diode X1 is off, the inductor L1 is selected so as to cancel the capacitance when the PIN diode X1 is off and the impedance is sufficiently large at a desired frequency in order to exhibit capacitance. The inductors L2 and L3 are also selected to be sufficiently large at a desired frequency so that the impedance of the control line is not affected.

  The resistor R1 is used for current adjustment, and is adjusted so that the resistance when the PIN diode X1 is on does not affect the antenna characteristics. When the antenna 13 is selected, the control signal becomes high level, a current flows through the inverter I1 via the PIN diode X1 and the resistor R1, and the second antenna 13 operates as an antenna. On the other hand, when the first antenna 12 is selected, the control signal is at a low level. At this time, the inverter output becomes a high level, a reverse bias voltage is applied to the PIN diode X1, and the PIN diode X1 is turned off.

  Here, although the ON resistance of the PIN diode X1 is about 1 to 2Ω, the ON resistance of the PIN diode X1 is high because the radiation resistance of the second antenna 13 is high as shown in FIG. The radiation loss at is sufficiently small and does not matter.

Here, in the technique disclosed in Patent Document 4, in general, when an antenna element of λ / 4 is used as an antenna element, as shown in FIG. 4B, its impedance (radiation resistance) is small. When an element having a resistance component such as a PIN diode is inserted in series, the antenna efficiency is deteriorated. However, when the circuit boards of the upper and lower casings are used as antenna elements as in this example, As described above, since the impedance (radiation resistance) is large, even if a PIN diode is inserted in series, the efficiency degradation due to the resistance of the PIN diode is small, and therefore the antenna is connected in series to the second antenna 13 as shown in FIG. it become possible to insert the switch 130.

  In FIG. 3, a PIN diode is used, but a GaAs switch or the like which is another switching element may be used.

  FIG. 5 is a diagram showing another embodiment of the present invention, in which an inverted F antenna is used as the first antenna 12, and FIG. 6 is a diagram showing still another embodiment of the present invention. There is an example in which an inverted L antenna is used as the first antenna 12. FIG. 7 is a diagram showing another embodiment of the present invention, which is an example in which a helical antenna is used as the first antenna 12. Thus, the same effect can be obtained regardless of the type of antenna used on the antenna 12 side.

  In addition, although the antenna connection switch 130 is put only in the 2nd antenna 13, you may provide a disconnection switch in both antennas. With this configuration, the second antenna 13 can be an antenna made up of an upper casing circuit board and a lower casing circuit board of a foldable mobile phone, and the first antenna 12 can be provided near the hinge portion. It becomes possible. And it becomes possible to reduce the phase circuit 133 of the 2nd antenna 13, and it becomes possible to reduce a passage loss.

  In each of the above embodiments, a mobile phone has been described. However, it is apparent that the present invention can be widely applied to portable wireless communication terminals in general.

1 is a perspective view of a mobile phone according to a first embodiment of the present invention. 1 is a circuit diagram of an antenna unit of a mobile phone according to a first embodiment of the present invention. FIG. 3 is a circuit diagram when a PIN diode is used for the antenna connection switch 130 of FIG. 2. (A) is a single impedance of the second antenna according to the first embodiment of the present invention, and (b) is a single impedance of a general λ / 4 antenna. It is a see-through | perspective perspective view of the mobile telephone which concerns on 2nd embodiment of this invention. It is a see-through | perspective perspective view of the mobile telephone which concerns on 3rd embodiment of this invention. It is a see-through | perspective perspective view of the mobile telephone which concerns on 4th embodiment of this invention. It is a perspective view of a conventional folding cellular phone. FIG. 9 is a side cross-sectional view showing a phase relationship between a high-frequency current flowing through the upper housing and a high-frequency current flowing through the lower housing in the portable wireless device of FIG. 8. It is a matching circuit diagram of the antenna part of the conventional portable radio | wireless terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper housing | casing 2 Lower housing | casing 3 Upper housing | casing front part 4 Upper housing | casing rear surface part 5 Lower housing | casing front surface part 6 Lower housing | casing rear surface part 7 Battery 8 Upper housing circuit board 9 Lower housing circuit board 10 Upper housing Circuit unit 11 Lower casing circuit unit 12 First antenna 13 Second antenna 18 Upper and lower circuit unit connection unit 19 Hinge unit 20 Display unit 21 Antenna selection switch 22 Transmission / reception circuit 121 Feeding terminal 122 Matching circuit 123 Phase shifter 130 Antenna connection switch 131 Feeding line 132 Matching circuit

Claims (4)

In addition to the first antenna, the portable radio terminal used as the second antenna by connecting the first and second circuit boards accommodated in each of the first and second casings by a feed line Because
When the first antenna is selected, the switch means to open said second antenna,
A matching circuit for the second antenna,
Providing the switch means between the feed line of the second antenna and the matching circuit;
The portable radio terminal characterized in that the switch means comprises a switch circuit using a PIN diode. The portable wireless terminal according to claim 1, wherein the first and second housings are connected to each other by hinges so as to be rotatable . The portable wireless terminal according to claim 1 or 2, wherein the first antenna is any one of a meander antenna, an inverted L antenna, an inverted F antenna, and a helical antenna . Portable wireless terminal in accordance with claim 1, characterized in that a mobile telephone.

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