Abstract:
A foldable portable wireless communication apparatus which ensures miniaturization of housing and good antenna characteristic has first casing including transmitter and/or operation section, and second housing including receiver and/or display section and rotatably linked with the first casing through hinge section provided on one end portion of the first housing on the front face side thereof. An antenna board is provided in area at back of the hinge section inside the first housing, and a circuit board having a radio-frequency circuit section mounted thereon is provided in area not overlapping the hinge section inside the first housing. A connection conductor connecting the antenna board and the high frequency wave input/output point of the radio-frequency circuit section is configured into a monopole antenna by setting the direction of extension of the connection conductor in the lengthwise direction of the first housing in the vicinity of the high frequency wave input/output point.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a foldable portable wireless communication apparatus, and more particularly, a foldable portable wireless communication apparatus which has a built-in antenna.  
         [0003]     2. Description of the Related Art  
         [0004]     Cellular phones become very popular as foldable portable wireless communication apparatuses. Some of such cellular phones incorporate an antenna in a casing, i.e., they have a built-in antenna.  
         [0005]     For example, in a foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535, an operation-side housing provided with a transmitter microphone, a key operation section, and the like extends upward beyond a hinge section provided on one end portion of the anterior surface of the housing. The foldable cellular phone employs a structure that an antenna is housed in an area extending from below the hinge section to an extended part of the operation-side housing.  
         [0006]     As the foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535 is structured to house the antenna behind the hinge section, the foldable cellular phone is unlikely to be affected by a human body at the time of talking, and is superior in terms of high packing density of parts.  
         [0007]     In the case of the structure of the foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535, however, when a display-side housing is folded toward the operation-side housing, the antenna housing portion of the operation-side housing protrudes upwardly beyond the hinge section. Accordingly, the foldable cellular phone is not preferable in design, and has not achieved sufficient miniaturization of the casing.  
         [0008]     In a case where a protrusive portion is not provided, as an antenna housing section is shortened in the lengthwise direction of the housing, the built-in antenna should be shortened in the lengthwise direction by what corresponds to the shortened length of the antenna housing section. Therefore, the structure having no protrusive portion is brings about a disadvantage that the gain of a vertical polarization component at the built-in antenna decreases.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is made in view of the aforementioned circumstance, and it is an object of the invention is to provide a foldable portable wireless communication apparatus which ensures miniaturization of a casing and a good antenna characteristic.  
         [0010]     To achieve the object, a foldable portable wireless communication apparatus of the invention comprises: 
        a first housing having at least one of a transmitter and an operation section;     a second housing which has at least one of a receiver and a display section, and is rotatably linked with the first housing through a hinge section provided on one end portion of the first housing on a front face side thereof;     a first antenna element provided in an area which is a back of the hinge section inside the first housing;     a circuit board provided in an area not overlapping the hinge section inside the first housing, and having a radio-frequency circuit section mounted thereon; and     a connection conductor which connects the first antenna element and a high frequency wave input/output point of the radio-frequency circuit section on the circuit board, extends along a lengthwise direction of the first housing in the vicinity of the high frequency wave input/output point, and is so configured into a monopole antenna as a second antenna element.        
 
         [0016]     The connection conductor constitutes a quarter-wave antenna together with the first antenna element.  
         [0017]     Each of electrical lengths of the first antenna element and the connection conductor is approximately one-eighth of a wavelength in a communication band.  
         [0018]     The first antenna element is a linear antenna element.  
         [0019]     The first antenna element is a modified monopole antenna.  
         [0020]     The first antenna element is a thin planar antenna element.  
         [0021]     The first antenna element is formed on a printed board.  
         [0022]     The connection conductor comprises a metal plate.  
         [0023]     The metal plate is integrally molded with a resin by insert molding.  
         [0024]     According to the invention, it is not necessary to provide a protrusive portion on the side end portion of the hinge section, thus miniaturizing a housing. A shortfall of a gain of a vertical polarization component by the first antenna element miniaturized as a built-in antenna is complemented by the connection conductor which is configured into a monopole antenna as the second antenna element, and connects the first antenna element and the high frequency wave input/output point of the radio-frequency circuit section on the circuit board, thus improving an antenna characteristic. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     These objects and other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which:  
         [0026]      FIG. 1  is a perspective view illustrating the structure of a foldable cellular phone as a folding portable wireless communication apparatus to which the invention is applied according to one embodiment, as viewed from the front side with the cellular phone opened;  
         [0027]      FIG. 2  is an exploded perspective view illustrating a foldable cellular phone closed as viewed from the rear side, and is an exploded view with a battery unit removed;  
         [0028]      FIG. 3  is a perspective view illustrating a front cover (top casing) of an operation-side unit (first housing), hinge caps, hinge covers, internal modules, and the like removed in the open state of  FIG. 1 ;  
         [0029]      FIG. 4  is an explanatory perspective view of the structure of an antenna section illustrating the battery unit of the operation-side unit, a rear cover (bottom cover), the hinge caps, and the like removed in the close state of  FIG. 2 ;  
         [0030]      FIG. 5  is a cross-sectional view illustrating the cross-sectional structure of a hinge section side, and illustrating an area covered by the hinge cover integrated with a key top plate;  
         [0031]      FIG. 6  is a cross-sectional view illustrating the cross-sectional structure of the hinge section side, and illustrating the area covered by the hinge cover integrated with the key top plate;  
         [0032]      FIG. 7A  is a perspective view illustrating an antenna connection conductor (part) as viewed from the same direction as that of  FIG. 3 ;  
         [0033]      FIG. 7B  is a perspective view illustrating the antenna connection conductor (part) as viewed from the same direction as that of  FIG. 4 ; and  
         [0034]      FIG. 8  is a plan view illustrating a modification of an antenna pattern. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]     A best mode for carrying out the invention will be elaborated with reference to the accompanying drawings.  
         [0036]      FIG. 1  illustrates a foldable cellular phone as an embodiment of a foldable portable wireless communication apparatus to which the invention is applied opened. A first housing  1  and a second housing  2  are rotatably linked with each other by a hinge section  3 .  
         [0037]     The first housing  1  is constituted by combining a top casing  4 , a bottom casing  5  (see  FIGS. 2 and 3 ) and a bottom cover  6 . The first housing  1  has various key switches (operation section)  7 , a microphone (transmitter)  8 , and a key top plate  9  provided on the top casing  4  which overlaps the second housing  2  in a folded state.  
         [0038]     The second housing  2  is constituted by combining a top casing  11  and a bottom casing  12 . The second housing  2  has a liquid crystal display screen (display section)  13 , a receiver  14  and a logo plate  15  provided on the top casing  11  which overlaps the first housing  1  in a folded state.  
         [0039]     As illustrated in  FIG. 3 , the hinge section  3  has brackets  10 ,  10  provided on the bottom casing  5  of the first housing  1  and brackets  20 ,  20  provided on the bottom casing  12  of the second housing  2  and interlined with the respective brackets  10 ,  10  by a hinge unit. Each of the outward brackets  10 ,  10  is covered with a hinge cap  16 . Aportion between the hinge caps  16 ,  16  is covered by a pair of a hinge cover  17  integral with the key top plate  9  and a hinge cover  27  attached to the bottom casing  5  of the first housing  1  (see  FIG. 3 ), and pairs of hinge covers  18 ,  19  integral with the logo plate  15  and respective hinge covers  28 ,  29  attached to the bottom casing  12  of the second housing  2  (see  FIG. 3 ).  
         [0040]      FIG. 2  illustrates a disassembly state where a battery unit  21  is removed with the foldable cellular phone closed as viewed from the rear side. A battery housing section  22  which is for loading the battery unit  21  is formed on the bottom casing  5  and the bottom cover  6  of the fast housing  1 . A speaker  23 , a battery attachment/detachment operation lever  24 , a connector cover  25 , and an antenna cover  26  are assembled with the bottom casing  5  and the bottom cover  6 .  
         [0041]      FIG. 3  illustrates the logo plate  15  which is integral with the hinge covers  18 ,  19 , the key top plate  9  which is integral with the hinge cover  17 , the hinge caps  16 , the top casing  4  of the first housing  1 , the connector cover  25 , internal modules, and the like removed in the open state of  FIG. 1 . The hinge cover  27  is attached to the bottom casing  5  of the first housing  1 , and the hinge covers  28 ,  29  are attached to the bottom casing  12  of the second housing  2 . The hinge covers  28 ,  29  are integral with each other.  
         [0042]     As illustrated in the figure, a packing groove  31  is formed around the bottom casing  5  of the first housing  1 . A hole  32  for an FPC and a hole  33  for an antenna are formed in the left and right of the end surface of the hinge section  3  side of the bottom casing  5 , respectively, and the one end side of an antenna connection conductor  34  fitted into the antenna hole  33  protrudes therefrom.  
         [0043]     A speaker attachment section  35  is provided inside the bottom casing  5 . A lock mechanism  36  which operates together with the battery attachment/detachment operation lever  24  and holds the battery unit  21  (see,  FIG. 2 ) in a loaded state, and a vibrator  37  for incoming announcement are assembled inside the bottom casing  5 .  
         [0044]     A hole  38  for an FPC is formed in the end surface of the hinge section  3  side of the bottom casing  12  of the second housing  2 .  
         [0045]      FIG. 4  is for explaining the structure of an antenna section with the battery unit  21 , the bottom cover  6  of the first housing  1 , the hinge caps  16 , the antenna cover  26  and the like removed in the close state of  FIG. 2 .  
         [0046]     As illustrated in the figure, an antenna housing recess portion  41  is formed along the end portion of the hinge section  3  side behind the hinge section  3 . The antenna hole  33  (see,  FIG. 3 ) reaches the antenna housing recess portion  41 . Therefore, the other end section of the antenna connection conductor  34  protrudes inside the antenna housing recess portion  41 .  
         [0047]     As illustrated in  FIG. 4 , inside the antenna housing recess portion  41 , an antenna board fixing surface  41   a  is formed on the left, and a rib  41   b  for holding the antenna board is formed on the right. The antenna board fixing surface  41   a  and the antenna board holding rib  41   b  have the same height, and an antenna board  43  is mounted on the antenna board fixing surface  41   a  and the antenna board holding rib  41   b.    
         [0048]     A packing groove  42  is formed around the antenna housing recess portion  41 . An antenna packing (waterproof cover)  44  is fitted into the packing groove  42 .  
         [0049]     As illustrated in the figure, the antenna board  43  has a meanunder line linear antenna patterned on a rigid board (a hard printed board). That is, an electrode  43   a  for power feeding is formed on the antenna board  43 , and meanunder line antenna elements  43   b,    43   c  made by patterning copper films are formed on the right and the left of the feeding electrode  43   a.    
         [0050]     In  FIG. 4 , the menunder line antenna element  43   b  on the left is for communication, and the menunder line antenna element  43   c  on the right is for GPS (Global Positioning System). Both antenna elements  43   b,    43   c  are modified monopole antennas. The antenna elements  43   b,    43   c  are thin planer monopole antennas.  
         [0051]     The antenna board  43  integrally has a spring connector  43   d  which protrudes from the feeding electrode  43   a  to the opposite side.  
         [0052]     The antenna packing  44  works as a waterproof cover, and has a seal lip section  44 a therearound.  
         [0053]     As illustrated in  FIG. 7A , the antenna connection conductor  34  is structured by molding a metal plate  34   a  with a resin  34   b.  More specifically, the antenna connection conductor  34  is structured as a molded piece that the metal plate  34   a  is inserted in the resin  34   b  by insert molding.  
         [0054]     In the embodiment, the antenna connection conductor  34  is formed in an approximately L shape as illustrated in the figure, and the one end portion thereof has a circuit board side connection terminal  34   c  exposing the metal plate  34   a  (see  FIG. 7A ). As illustrated in  FIG. 7B , a small hole  34   d  is formed in the other end portion opposite to the circuit board side connection terminal  34   c  of the mold resin  34   b,  and a portion of the metal plate  34   a  exposed in the small hole  34   d  is an antenna board connection terminal  34   e.    
         [0055]     Next, how to assemble the antenna connection conductor  34  and the antenna board  43  will be explained.  
         [0056]     The antenna connection conductor  34  is inserted into the antenna hole  33  from the interior of the bottom casing  5  of the first housing  1  with the antenna board side connection terminal  34   e  being a leading end of the insertion. Accordingly, as illustrated in  FIG. 3 , the circuit board side connection terminal  34   c  side of the antenna connection conductor  34  is located at the side of the vibrator  37 . As illustrated in the figure, the circuit board side connection terminal  34   c  is, however, located at a place away from the vibrator. As illustrated in  FIG. 4 , the antenna board side connection terminal  34   e  side of the antenna connection conductor  34  is located in the antenna housing recess portion  41 . The antenna board side connection terminal  34   e  is located near the antenna board fixing surface  41   a  as illustrated in the figure.  
         [0057]     Next, the antenna board  43  is inserted into the antenna housing recess portion  41 . With the spring connector  43   d  being connected to the antenna board side connection terminal  34   e,  the antenna element  43   b  side of the antenna board  43  is bonded to the antenna board fixing surface  41   a  by a double-sided tape or the like. At this time, the antenna element  43   c  side of the antenna board  43  is supported by the antenna board holding rib  41   b.    
         [0058]     Subsequently, the seal lip section  44   a  around the antenna packing  43  is fitted into the packing groove  42  around the antenna housing recess portion  41 . The antenna housing recess portion  41  is covered by the antenna packing  43  for waterproofing.  
         [0059]      FIGS. 5 and 6  illustrate the cross-sectional structure of the hinge section  3  side. As illustrated in  FIGS. 5 and 6 , the foldable cellular phone firther has a circuit board  45 , electronic parts  46 ,  47 , and  48 , a connector  49 , a module frame (sealed casing)  51 , a sheet key  52 , a key pad  53 , a contact point spring  54 , a flexible wiring board (FPC)  55 , a waterproof cap  56 , a connector  57 , and a waterproof cap  58 . As illustrated in the figure, a seal lip section around the key pad  53  is fitted into the packing groove  31  of the bottom casing  5 .  
         [0060]     As illustrated in  FIG. 6 , inside the first housing  1  (bottom casing  5 ), the circuit board side connection terminal  34   c  of the antenna connection conductor  34  (see,  FIGS. 3 and 7 ) is connected to the high frequency wave input/output point of a radio-frequency circuit section mounted on the circuit substrate  45 , i.e., a feeding point for the antenna through the contact point spring  54 .  
         [0061]     As illustrated in the figure, the FPC  55  is provided in a space covered by the hinge covers  17 ,  27 , and the like. The FPC  55  connects the circuit board  45  in the first housing  1  (bottom casing  5 ) and a circuit board in the second housing  2  (bottom casing  12 ) with each other.  
         [0062]     That is, the one end side of the FPC is led to the interior of the first housing  1  (bottom casing  5 ) through the FPC hole  32  as illustrated in  FIG. 5 . The connector  57  is provided on the leading end of the one end side of the FPC  55 , and connected to the connector  49  on the circuit board  45 . The FPC hole  32  is sealed by the waterproof cap  56  which is integrally attached to the FPC  55 .  
         [0063]     As illustrated in  FIG. 6 , the other end side of the FPC  55  is led to the interior of the second housing  2  (bottom casing  12 ) through the FPC hole  38 . It is not illustrated, but a connector is provided on the leading end of the other end side of the FPC  55 . The other end side of the FPC  55  is connected to the circuit board through the non-illustrated connector in the second housing  2  (bottom casing  12 ). The FPC hole  38  is sealed by the waterproof cap  58  integrally attached to the FPC  55 .  
         [0064]     As mentioned above and illustrated in FIGS.  4  to  6 , in the embodiment, the antenna board  43  is disposed behind the hinge section  3 .  
         [0065]     The antenna on the antenna board  43 , i.e., the linear antenna elements  43   b,    43   c  are located on a surface away from the hinge section  3  of the antenna board  43  (i.e., a surface opposite to the hinge section  3  side) to reduce the affection from the FPC  55  (more specifically, the affection of an electromagnetic wave emitted from the FPC  55  and becoming a noise).  
         [0066]     The linear antenna elements  43   b,    43   c  on the antenna board  43  are connected to the high frequency wave input/output point (feeding point) of the radio-frequency circuit section mounted on the circuit board  45  through the antenna connection conductor  34 .  
         [0067]     That is, as illustrated in  FIGS. 7A and 7B , the antenna connection conductor  34  is formed in an approximately L shape, and the antenna board side connection terminal  34   e  is disposed behind the hinge section  3 , and is connected to the spring connector  43   d  (see,  FIGS. 4 and 6 ) of the antenna board  43 . The circuit board side connection terminal  34   c  side of the antenna connection conductor  34  passes through the antenna hole  33  formed in a partition wall which divides off the hinge section  3  and the first housing  1  (bottom casing  5 ) housing the circuit board  45  and the like (also works as the peripheral wall of the antenna housing recess portion  41 ), and runs into the first housing  1  (bottom casing  5 ). The circuit board side connection terminal  34   c  of the antenna connection conductor  34  running into the first housing  1  is connected to the contact point spring  54  provided on the circuit board  45  (see,  FIGS. 3 and 6 ). The contact point spring  54  is connected to the radio-frequency circuit section mounted on the circuit board  45 , and functions as the input/output point of a high frequency wave (feeding point for the antenna).  
         [0068]     In such a structure, an antenna current which flows through the antenna connection conductor  34  becomes maximum near the feeding point.  
         [0069]     In the embodiment, the portion of the antenna connection conductor  34  in the vicinity of the feeding point is configured into a monopole antenna, i.e., the portion of the antenna connection conductor  34  in the vicinity of the feeding point is disposed in such a manner as to extend along the lengthwise direction (direction to be vertical at the time of communication) of the housing, and work as a monopole antenna. The antenna connection conductor  34  configured into the monopole antenna is hybrid together with a built-in antenna. That is, the linear antenna elements  43   b,    43   c  and the antenna connection conductor  34  constitute a hybrid antenna.  
         [0070]     Accordingly, the portion configured into the monopole antenna contributes to transmission and reception of a vertical polarization component, thereby increasing the gain of a vertical polarization component.  
         [0071]     In portable wireless communication apparatuses like cellular phones, generally, a quarter-wave antenna whose electrical length is a quarter of a wavelength in a communication band is used.  
         [0072]     Therefore, in the embodiment, the antenna connection conductor  34  (metal plate  34   a  thereof) and the linear antenna element  43   b  on the antenna board  43  work together, and function as a quarter-wave antenna.  
         [0073]     Accordingly, the linear antenna element  43   b  itself on the antenna board  43  does not need to be quarter wavelength. Therefore, the antenna board  43  is miniaturized, and can be housed in a portion behind the hinge section  3  which cannot provide an enough space in the lengthwise direction of the first housing  1  (bottom casing  5 ).  
         [0074]     As a result, a protrusive portion is not required on the hinge section side end portion, thereby miniaturizing the first housing  1 .  
         [0075]     As the antenna board  43  which has the linear antenna element  43   b  as the built-in antenna is miniaturized, the gain of a vertical polarization component is reduced. However, the gain of a vertical polarization component is complemented by the linear antenna element  43   b  on the antenna board  43  and the antenna connection conductor  34  which constitutes the hybrid antenna and is configured into the monopole antenna. Therefore, the gain of a vertical polarization component increases.  
         [0076]     It is desirable that each of the electrical lengths of the linear antenna  43   b  (linear antenna for communication) on the antenna board  43  and the antenna connection conductor  34  should be one-eighth of a wavelength in a communication band, but functions well if it is approximately one-eighth. For example, even if the electrical length of the monopole antenna section is less than one-eighth of a wavelength in a communication band but is approximately one-eighth, it is possible to perform transmission and reception of a vertical polarization component well. That is, the gain of a vertical polarization component increases.  
         [0077]     In the embodiment, a structure that the vibrator is disposed near the antenna connection conductor  34  is employed as illustrated in  FIG. 3 , but an affection from the vibrator  37  (more specifically, the affection of a electromagnetic wave which is emitted from the vibrator  37  when the vibration  37  operates and becomes a noise) is minimized as the antenna connection conductor  34  is bent in a direction away from the vibrator  37 .  
         [0078]     It is not illustrated in the figure, but in the metal plate  34   a  portion of the antenna connection conductor  34 , a portion which connects the antenna board side connection terminal  34   e  and the circuit board side connection terminal  34   c,  i.e., the metal plate  34   a  portion running along the lengthwise direction of the first housing  1  (bottom casing  5 ) is molded in such a manner as to be located on a side away from the vibrator  37 . Because of this structure, the antenna connection conductor  34  is also not likely to be affected by the vibrator  37 .  
         [0079]     As illustrated in  FIG. 4 , the antenna board side connection terminal  34   e  of the antenna connection conductor  34  disposed behind the hinge section  3  is disposed in such a manner as to be pulled toward the partition wall which divides off the hinge section  3  side and the interior of the first housing  1  (bottom casing  5 ), and is unlikely to be affected by the FPC  55 .  
         [0080]      FIG. 8  illustrates an modification of the antenna pattern.  
         [0081]     As illustrated in the figure, an antenna board  61  is constituted by forming linear antenna elements  61   b,    61   c  which extend from an electrode  61   a  for power feeding to the external side and the center by patterning copper films.  
         [0082]     In the figure, an external thick linear antenna element  61   b  which extends from the left around the antenna board  61  is for communication. A central thin linear antenna element  61   c  which linearly extends toward the left is for GPS. Both of the linear antenna elements  61   b,    61   c  are modified monopole antennas.  
         [0083]     It is not illustrated in the figure, but the antenna board  61  integrally has a spring connector which protrudes from the feeding electrode  61   a  to the opposite side.  
         [0084]     In the aforementioned embodiment, the explanation has been given of a case where the cellular phone is taken as an example of the foldable portable wireless communication apparatus, but the invention is not limited to this case, and may be applied to a laptop computer, a PDA (Personal Digital Assistance), and other portable wireless communication apparatuses having a wireless communication function.  
         [0085]     A foldable portable wireless communication apparatus may be one that the first housing has at least a transmitter and the second housing has a receiver, or one that the first housing has an operation section and the second housing section has a display section.  
         [0086]     In the embodiment, although a case where the antenna connection conductor is constituted by a resin molded metal plate is taken as an example, but a non-resin-molded metal plate or metal wires may be used.  
         [0087]     The shape or the like of the antenna disposed behind the hinge section is arbitrary, and it is needless to say that other specific details and structures are changeable appropriately. For example, the antenna disposed behind the hinge section may be a linear antenna, and may be a wire antenna formed in an arbitrary shape like a helical antenna, an antenna which is a bent long and thin metal plate, as well as one which has an antenna pattern formed on a flexible board instead of a rigid board. In a case where an antenna pattern is formed on a flexible board by a copper film, a conductive material which connects the antenna pattern and a feeding point may be formed by a copper film pattern.  
         [0088]     Various embodiments and changes may be made thereunto without departing from the broad spirit and scope of the invention. The above-described embodiment is intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiment. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.  
         [0089]     This application claims priorities of Japanese Patent Application No. 2005-211695 filed on Jul. 21, 2005 and Japanese Patent Application No. 2006-88117 filed on Mar. 28, 2006, and the contents of which incorporated herein in their entirety.