JP2009164772A - Mobile phone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile phone having an excellent antenna performance even when a person holds a terminal for the radio waves of at least two kinds of frequency bands. <P>SOLUTION: The mobile phone has: a first antenna provided on one end or the other end in the longitudinal direction of a first case held by a user, for receiving the radio waves of a first frequency band; and a second antenna provided on each of one end and the other end of the first case, for receiving the radio waves of a second frequency band which is different from the first frequency band. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile phone having a radio communication function of radio waves in at least two types of frequency bands.

It is known that the antenna performance of a wireless device deteriorates when a human body is in close proximity. In small portable wireless devices such as mobile phones, in recent years, the design of terminals has been emphasized, and demands for thinning and miniaturization of terminals have increased. In terms of functionality, the number of terminals is increasing in functionality, such as mounting a WLAN (Wireless Local Area Network) communication function and a terrestrial digital TV reception function on a mobile phone (see Patent Document 1).
JP 2004-207880 A

  As described above, the mobile phone is required not only to be thin and small, but also to receive radio waves of a plurality of types of frequency bands due to its multi-function. In order to obtain a certain level of communication quality when receiving radio waves in each frequency band, it is better to increase the physical distance between the antenna and the human body as much as possible, but it is difficult to secure that distance. Yes.

  The present invention has been made to solve the above-described problems of the technology, and a portable device having good antenna performance even if a person holds a terminal for radio waves of at least two types of frequency bands. The purpose is to provide a telephone.

In order to achieve the above object, the cellular phone of the present invention provides:
A first antenna for receiving radio waves in the first frequency band, provided at one end or the other end in the longitudinal direction of the first housing held by the user;
The second casing is provided at each of one end and the other end of the first casing and receives radio waves in a second frequency band that is a frequency band different from the first frequency band. An antenna,
It is the structure which has.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that communication quality deteriorates even if a part of human body approaches a terminal about a radio wave of at least 2 or more types of frequency bands, when a person holds a terminal.

  Examples of the mobile phone according to the present embodiment will be described. In the present embodiment, the case where the mobile phone is a foldable terminal will be described.

(First embodiment)
The mobile phone of this embodiment will be described. In the present embodiment, two types of frequency bands are considered, that is, two types of frequencies, a frequency for telephone communication and a frequency for WLAN. The frequency band of the radio wave for telephone communication is set to 800 MHz, and the frequency band of the radio wave for WLAN communication is set to 2400 MHz. Actually, the usable frequency width is determined for each, but the detailed description thereof is omitted here.

  FIG. 1 is a diagram illustrating a configuration example of a mobile phone according to the present embodiment. FIG. 1A is a perspective view in a state where the mobile phone is opened.

  As shown in FIG. 1A, the mobile phone has a lower casing 17 including a communication circuit board 12 for communication processing and an upper casing 15 including a display circuit board 13 for displaying a screen. . The upper housing 15 and the lower housing 17 are connected by a hinge portion 16. FIG. 1B is an external perspective view showing an example of the hinge portion.

  In FIG. 1B, a part of the upper casing 15 and the lower casing 17 are shown in the figure, and the other parts are not shown in the figure. The lower housing 17 corresponds to the first housing of the present invention, and the upper housing 15 corresponds to the second housing of the present invention.

  In the present embodiment, each of the upper housing 15 and the lower housing 17 is a rectangular parallelepiped having a predetermined thickness. FIG. 1 shows a state in which the cellular phone is opened, but it is possible to fold one of the upper casing 15 and the lower casing 17 by rotating the casing toward the other side about the hinge portion 16 as an axis. . When making a call using the phone function of the mobile phone, the user usually holds the mobile phone with the two long sides of the lower housing 17 touching his / her finger while the mobile phone is open as shown in FIG. To do.

  The upper casing 15 is provided with a display circuit board 13 for operating a display (not shown), and the lower casing 17 is provided with a communication circuit board 12 for communication processing. The communication circuit board 12 and the display circuit board 13 are connected by a flexible cable 14.

  The hinge unit 16 is provided with a telephone communication antenna 1 and a WLAN communication first antenna 51. Since these antennas are provided inside the hinge portion 16, they cannot be seen in the external perspective view of FIG. In the lower housing 17, a second WLAN communication antenna 52 is provided at the end opposite to the hinge portion 16.

  As described above, the first WLAN communication antenna 51 is arranged on the hinge portion 16 corresponding to one end of the lower casing 17 in the longitudinal direction, and the second WLAN communication antenna 52 is disposed in the longitudinal direction of the lower casing 17. It is arranged at the other end. The length of the antenna for WLAN communication is a value of λ / 4 or 3λ / 4, where λ is a wavelength of a radio wave having a frequency of 2400 MHz.

  The WLAN communication first antenna 51 and the WLAN communication second antenna 52 correspond to the first antenna of the present invention, and the telephone communication antenna 1 corresponds to the second antenna of the present invention.

  Each antenna includes a resonant circuit unit that amplifies received radio waves in a desired frequency band and prevents mutual coupling between adjacent antennas, a radio circuit unit that demodulates received signals and modulates transmitted signals, and an antenna side A matching circuit unit for matching impedance on the wireless circuit unit side is connected.

  Referring to FIG. 1, the matching circuit unit 5 and the resonance circuit unit 8 are connected to the first WLAN communication antenna 51. Further, the matching circuit unit 6 and the resonance circuit unit 9 are connected to the second antenna 52 for WLAN communication. The resonant circuit unit 8 and the resonant circuit unit 9 are connected to the wireless circuit unit 11. A matching circuit unit 4, a resonance circuit unit 7, and a radio circuit unit 10 are connected to the telephone communication antenna 1.

  FIG. 2 is a block diagram showing a configuration example of the communication circuit board.

  A control unit 55 not shown in FIG. 1 is provided on the communication circuit board 12, and the wireless circuit unit 11 and the wireless circuit unit 10 are connected to the control unit 55. In addition, a speaker 58 provided in the upper housing 15 and an operation unit 56 and a microphone 57 provided in the lower housing 17 are connected to the control unit 55. The control unit 55 is provided with a CPU (Central Processing Unit) (not shown) for executing processing according to a program and a memory (not shown) for storing the program. Note that the control unit 55 may include a DSP (Digital Signal Processor) for processing analog signals and digital signals at high speed.

  The radio circuit units 10 and 11 demodulate the high frequency signal received via the antenna and pass it to the control unit 55. When the control unit 55 receives the compressed signal from the radio circuit units 10 and 11, the control unit 55 returns the signal to the original and outputs it from the speaker 58. The radio circuit unit 11 examines the reception sensitivities of the radio waves received via the two WLAN communication antennas, and selects the one having the higher reception sensitivity as the signal processing target. Thus, the radio circuit unit 11 performs diversity control.

  Since the present embodiment relates to a radio wave reception operation, a detailed description of radio wave transmission processing is omitted. In FIG. 2, radio waves are transmitted and received via each of the two WLAN communication antennas, but either one may be dedicated to reception.

  In general, antenna diversity is implemented for fading compensation. However, in a small terminal such as a mobile phone, there is a degree of freedom in how a person holds the housing, and when a human body is close to the antenna, the antenna performance is deteriorated. Therefore, in this embodiment, considering the antenna performance degradation due to the proximity of the human body, the antenna for WLAN communication is arranged at the hinge portion corresponding to the upper end portion of the lower housing and the lower end portion away from the hinge portion. . Therefore, even if one of the two antennas is covered with a hand and the antenna performance deteriorates, the other antenna functions.

  Next, the configuration from the antenna to the radio circuit unit will be described in detail.

  In order to suppress mutual coupling between the antennas and obtain isolation, it is considered ideal to short the other antennas to the substrate ground or to disconnect the connection with the radio circuit unit. In order to approximate the ideal condition, a resonance circuit unit is connected to each antenna.

  FIG. 3 is a diagram illustrating a configuration example from the antenna for telephone communication to the radio circuit unit.

  As shown in FIG. 3, the matching circuit unit 4 and the radio circuit unit 10 are connected in series, and the resonance circuit unit 7 is connected in parallel. A resonance circuit unit 7 is connected between a point A between the matching circuit unit 4 and the radio circuit unit 10 and the ground. In this circuit, the impedance when the direction of the arrow shown in the figure from the point A is viewed is OPEN (open) when the frequency of the received radio wave is 800 MHz for telephone communication, and SHORT (short circuit) for the 2400 MHz band for WLAN communication. ).

  As an example of the resonance circuit unit 7, a configuration in which a capacitor and a coil are connected in parallel can be considered. In this case, the capacitor C of the capacitor, the reactance L of the coil, and the resonance frequency f0 are expressed by a relationship of f0 = 1 / (2π√LC). L and C can be obtained by solving the simultaneous equations with the resonance frequency impedance Z being Z = 0 at a certain frequency f1 and Z = ∞ at a certain frequency f2.

  FIG. 4 is a graph showing an example of impedance characteristics of the resonance circuit unit. Here, a resonance circuit unit 7 in which a capacitor and a coil are connected in parallel is used. The resistance value is 50Ω.

  In the graph shown in FIG. 4, the impedance becomes zero at the left end of the horizontal axis and becomes infinite at the right end of the horizontal axis. At a frequency of 850 MHz indicated by the marker 201, the impedance is a value close to infinity. On the other hand, at the frequency of 2450 MHz indicated by the marker 202, the impedance is a value close to zero.

  As described above, the impedance of the resonance circuit unit 7 can be adjusted to be OPEN in the 800 MHz band for telephone communication and SHORT in the 2400 MHz band for WLAN communication.

  The resonance circuit portions 8 and 9 of the first WLAN communication antenna 51 and the second WLAN communication antenna 52 are adjusted to have characteristics opposite to those of the resonance circuit portion 7 for telephone communication. That is, the impedance of the resonance circuit units 8 and 9 is adjusted to be OPEN in the WLAN communication frequency band and SHORT in the telephone communication frequency band. This can be set using the relational expression of the resonance frequency and the Smith chart shown in FIG. 4 as in the case of the resonance circuit unit 7.

  Next, a configuration example of the matching circuit unit will be described.

  FIG. 5 is a diagram illustrating a configuration example of the matching circuit unit. FIG. 5A shows a matching circuit called a T type. A capacitor 71 is connected in parallel between the coils 61 and 62 connected in series. FIG. 5B shows a matching circuit called a π type. A capacitor 72 is connected in parallel to one end of the coil 63, and a capacitor 73 is connected in parallel to the other end of the coil 63. The reactance of the coil and the value of the capacitor of the capacitor are set so that the impedances on the antenna side and the radio circuit unit side are close to each other.

  Next, the operation of the resonance circuit unit 7 will be described with reference to FIGS.

  With respect to the 800 MHz band radio wave used for telephone communication, the circuit configuration shown in FIG. 6 is established, and the impedance of the resonance circuit unit 7 is opened (opened). Therefore, the influence of the resonance circuit unit 7 is almost eliminated. On the other hand, with respect to radio waves in the WLAN communication frequency band, the circuit configuration is as shown in FIG. 7, and the impedance of the resonant circuit unit 7 is short-circuited. Therefore, an ideal state in which the telephone communication antenna is short-circuited to the substrate ground in the WLAN communication frequency band can be realized.

  In contrast to the resonant circuit unit 7, the resonant circuit units 8 and 9 have an impedance of zero when receiving radio waves in the WLAN communication frequency band, and an infinite impedance when receiving radio waves in the telephone communication frequency band. Become. The antenna for WLAN communication is in a state where it cannot receive radio waves in the telephone communication frequency band, and is in a state where it can receive radio waves in the WLAN communication frequency band.

  According to the present embodiment, since the antenna for WLAN communication is arranged at the upper end and the lower end of the lower housing, the antenna performance is deteriorated, for example, one of the two antennas is covered with a hand. Even so, the other antenna functions. It is possible to suppress deterioration in communication quality when a part of the human body approaches the antenna. A radio wave having a higher frequency than a radio wave used for telephone communication, such as a radio wave for WLAN communication, has a large space loss and a large influence on the radio wave reception sensitivity by a nearby human body. It is valid.

  If the antenna for WLAN communication and the antenna for telephone communication are close to each other, the antenna for WLAN communication may be mutually coupled with the antenna for telephone communication, and the antenna performance may be deteriorated. In this embodiment, since the resonance circuit operates corresponding to the frequency band of the received radio wave, the antenna performance degradation of the WLAN communication antenna due to mutual coupling with the mobile phone communication antenna can be reduced.

  This embodiment is more effective when there is a design or design limitation such that a whip antenna cannot be provided in the upper casing due to a demand for thinning the upper casing of the mobile phone.

(Second Embodiment)
In the present embodiment, the connection of the resonance circuit unit is different from that in the first embodiment. Other configurations are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  As a connection method of the resonance circuit unit different from that of the first embodiment, a case of the resonance circuit unit 7 corresponding to the telephone communication antenna 1 will be described.

  FIG. 8 is a diagram showing an example of how to connect the resonance circuit unit in the present embodiment.

  As shown in FIG. 8, the resonance circuit unit 7 is connected in parallel between the telephone communication antenna 1 and the matching circuit unit 10. However, as in the first embodiment, the impedance of the resonant circuit unit 7 is OPEN when the frequency of the received radio wave is in the telephone communication frequency band, and is SHORT when it is in the WLAN communication frequency band. Have been adjusted so that. The method of adjustment is the same as in the first embodiment. The resonance circuit units 8 and 9 can be connected in the same manner as the configuration shown in FIG.

  Next, as a method of connecting the resonance circuit unit, a case where the resonance circuit unit is connected in series with the wireless circuit unit and the matching circuit unit will be described. Here, the case of the resonant circuit unit 7 corresponding to the telephone communication antenna 1 will be described.

  FIG. 9 is a diagram illustrating an example of connecting the resonance circuit unit in series with the wireless circuit unit and the matching circuit unit.

  As shown in FIG. 9, the resonant circuit unit 7 is connected in series between the matching circuit unit 4 and the wireless circuit unit 7. In this case, the resonance circuit unit 7 is adjusted to be SHORT when the frequency of the received radio wave is in the telephone communication frequency band and to be OPEN when the frequency is in the WLAN communication frequency band. The method of adjustment is the same as the method used in the first embodiment.

  The resonance circuit portions 8 and 9 can be connected in the same manner as the configuration shown in FIG. In this case, the resonance circuit units 8 and 9 are adjusted to be SHORT when the frequency of the received radio wave is in the WLAN communication frequency band, and to be OPEN when the frequency is in the telephone communication frequency band. The method of adjustment is the same as the method used in the first embodiment.

  In addition, as shown in FIG. 10, a resonance circuit unit 7 may be connected in series between the telephone communication antenna 1 and the matching circuit unit 4. Similarly, for the WLAN communication antenna system, the resonance circuit unit 8 may be connected in series between the WLAN communication first antenna 51 and the matching circuit unit 5, and the resonance circuit unit 9 is connected to the second WLAN communication antenna. You may connect in series between the antenna 52 and the matching circuit unit 6.

  Also in this embodiment, the same effect as the first embodiment can be obtained.

(Third embodiment)
In the first and second embodiments, the case of the frequency band for telephone communication and the frequency band for WLAN communication having a higher frequency than the frequency band for telephone communication as the two or more types of frequency bands has been described. This embodiment is a case of a frequency band for telephone communication and a frequency band for terrestrial digital television having a lower frequency than the frequency band for telephone communication.

  In this embodiment, the frequency band for WLAN communication is replaced with the frequency band for terrestrial digital television in the first embodiment. Antennas are provided at both ends in the longitudinal direction of the lower housing 17 for transmitting or receiving radio waves in a relatively low frequency band of the two types of frequency bands. In this case, the length of the antenna is made to correspond to the wavelength.

  Also, when the resonance circuit units 8 and 9 receive radio waves in the frequency band for telephone communication, both ends of the resonance circuit units 8 and 9 are short-circuited and receive radio waves in the frequency band for terrestrial digital television. Is set to be open. The resonance circuit unit 7 is open when receiving radio waves in the frequency band for telephone communication, and short-circuits both ends of the resonance circuit unit 7 when receiving radio waves in the frequency band for terrestrial digital television. Is set to

  Also in this embodiment, the same effect as the first embodiment can be obtained.

  Further, the second embodiment may be applied to this embodiment. The resonant circuit units 8 and 9 are open when receiving radio waves in the frequency band for telephone communication, and are connected to the resonant circuit units 8 and 9 when receiving radio waves in the frequency band for terrestrial digital television. It is set so that both ends are short-circuited. The resonance circuit unit 7 is short-circuited at both ends of the resonance circuit unit 7 when receiving radio waves in the frequency band for telephone communication, and is opened when receiving radio waves in the frequency band for terrestrial digital television. Is set to

  As described above, even when the frequency band for telephone communication and the frequency band having a frequency lower than the frequency band for telephone communication are used as the two types of frequency bands, the same effect as the first embodiment can be obtained.

  In the first to third embodiments, not only the configuration shown in FIG. 1 but also the telephone communication antenna 1 may be provided at the lower end of the lower housing 17 as shown in FIG. Even if the antenna for telephone communication is arranged at the lower end of the lower housing 17, the same effect as in the first embodiment can be obtained.

  In the above-described embodiment, the case of a foldable mobile phone has been described. However, a mobile phone of a type in which an upper housing is slid on a lower housing or a mobile phone having a single housing may be used. . In any type of mobile phone, the case held by the user corresponds to the first case in the present invention.

It is a figure which shows one structural example of the mobile telephone of 1st Embodiment. It is a block diagram which shows the example of 1 structure of a communication circuit board. It is a figure which shows one structural example from the antenna for telephone communications to a radio | wireless circuit part. It is a graph which shows an example of the impedance characteristic of a resonance circuit part. It is a figure which shows an example of a matching circuit part. It is a figure for demonstrating operation | movement of a resonance circuit part. It is a figure for demonstrating operation | movement of a resonance circuit part. It is a figure which shows an example of the connection method of the resonance circuit part in 2nd Embodiment. It is a figure which shows an example in the case of connecting a resonance circuit part in series with a radio | wireless circuit part and a matching circuit part. It is a figure which shows another example in the case of connecting a resonance circuit part in series with a radio | wireless circuit part and a matching circuit part. It is a figure which shows another example of arrangement | positioning about the antenna for telephone communications.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 Upper housing | casing 17 Lower housing | casing 51 1st antenna for WLAN communication 52 2nd antenna for WLAN communication

Claims (6)

A first antenna for receiving radio waves in the first frequency band, provided at one end or the other end in the longitudinal direction of the first housing held by the user;
The second casing is provided at each of one end and the other end of the first casing and receives radio waves in a second frequency band that is a frequency band different from the first frequency band. An antenna,
A mobile phone having. A first matching circuit unit and a first wireless circuit unit are provided in series in the first housing to the first antenna, and between the first antenna and the first matching circuit unit or the first antenna A first resonant circuit unit is provided between the matching circuit unit and the first wireless circuit unit and the ground;
A second matching circuit unit and a second wireless circuit unit are provided in series with the second antenna on the first housing, and between or between the second antenna and the second matching circuit unit. A second resonant circuit unit is provided between the two matching circuit units and the second radio circuit unit and the ground,
When the first resonant circuit unit receives radio waves of the first frequency band, both ends of the first resonant circuit unit are short-circuited, and when receiving radio waves of the second frequency band Set to open,
The second resonance circuit unit is in an open state when receiving radio waves in the first frequency band, and is in an open state when receiving radio waves in the second frequency band. The mobile phone according to claim 1, wherein both ends are set to be short-circuited. A first radio circuit unit corresponding to the first antenna and a second radio circuit unit corresponding to the second antenna are provided in the first housing;
Between the first antenna and the first radio circuit unit, a first resonance circuit unit and a first matching circuit are provided connected in series in that order or in the reverse order,
Between the second antenna and the second radio circuit unit, a second resonant circuit unit and a second matching circuit are connected in series in that order or vice versa,
The first resonant circuit unit is in an open state when receiving radio waves in the first frequency band, and is in an open state when receiving radio waves in the second frequency band. Both ends are set to short circuit,
The second resonance circuit section is short-circuited when receiving the radio wave of the first frequency band, and opened when receiving the radio wave of the second frequency band. The mobile phone according to claim 1, wherein the mobile phone is set to be The first radio circuit unit includes:
Diversity control is performed on the first antenna provided at one end of the first casing and the first antenna provided at the other end of the first casing. 4. The mobile phone according to any one of 3 above. A second housing connected to the first housing via a hinge portion;
The mobile phone according to any one of claims 1 to 4, wherein one end of the first housing is the hinge portion.   The mobile phone according to any one of claims 1 to 5, wherein the second frequency band is a frequency higher than the first frequency band.

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