Abstract:
A slide-type wireless terminal apparatus includes a first casing and a second casing slidable relative to the first casing. The wireless terminal apparatus includes a first circuit board which is provided in the first casing, an antenna which is provided in the first casing, a second circuit board which is provided in the second casing, a sliding member which is disposed between the first circuit board and the second circuit board, the sliding member including a portion which faces the antenna, the sliding member having electrical conductivity and being electrically connected to the first circuit board, and a guide member which is provided in the second casing, the guide member being for guiding the sliding member such that the sliding member slides relative to the guiding member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2010-249185, filed on Nov. 5, 2010, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiment discussed herein is related to a slide-type wireless terminal apparatuses. 
       BACKGROUND 
       [0003]    A known slide-type wireless terminal apparatus includes two casings, that is, a fixed casing and a movable casing. The movable casing is slidable relative to the fixed casing. 
         [0004]      FIGS. 1A and 1B  respectively illustrate a plan view and side view of an example of a slide-type wireless terminal apparatus in a casing-closed state, and  FIG. 1C  illustrates a side view of the example of the slide-type wireless terminal apparatus in a casing-open state. 
         [0005]    A slide-type wireless terminal apparatus  1  includes a fixed casing  2  and a movable casing  3 . The fixed casing  2  includes components such as a battery and an antenna  4 . The movable casing  3  includes a display portion  5 . 
         [0006]      FIGS. 2A and 2B  respectively illustrate sectional views of the example of the slide-type wireless terminal apparatus in the casing-open state and the casing-closed state. 
         [0007]    The fixed casing  2  is provided with a slide module  7  in a surface that contacts the movable casing  3 , and the movable casing  3  is provided with a rail plate  8  in a surface that contacts the fixed casing  2 . The slide module  7  of the fixed casing  2  is engaged with the rail plate  8  of the movable casing  3  so as to allow the movable casing  3  to slide. Thus, the state of the slide-type wireless terminal apparatus  1  changes from the casing-open state illustrated in  FIG. 2A  to the casing-closed state illustrated in  FIG. 2B , and from the casing-closed state to the casing-open state. 
         [0008]    In the related art fixed casing  2 , a distal end of the slide module  7  does not extend to the antenna  4  position in the Y direction, which is the longitudinal direction of the casing. The antenna  4  and the slide module  7  are disposed such that the slide module  7  and the antenna  4  do not oppose each other in the Z direction. 
         [0009]    A technology is disclosed, in which an electrically conductive member is electrically connected to a ground pattern of a lower board and disposed at a position that is on a surface opposing a surface of the lower board in which an antenna element is disposed and that allows the electrically conductive member to be capacitively coupled to a flexible cable. In the technology, when a lower casing and an upper casing are closed, the electrically conductive member serves as a ground plate for the antenna element. In a slid open state, in which the upper casing has been slid relative to the lower casing, the electrically conductive member is capacitively coupled to the flexible cable so as to obtain an optimum capacitance as well as serving as a ground plate for the antenna element, thereby causing the current flowing in the lower board and the current flowing in the upper board to be in phase (refer to, for example, Japanese Laid-open Patent Publication No. 2009-194689). 
         [0010]    A slide-type mobile phone including a board for operation portion having an antenna element formed on the board is also known (refer to, for example, Japanese Laid-open Patent Publication No. 2006-325098). 
         [0011]    There is also a known technology in which a chip antenna is mounted on a board such that a power feeding terminal side of an antenna conductor overlaps a ground pattern, and a portion of the antenna that is closer to an end than the power feeding terminal side portion does not overlap the ground pattern. The chip antenna includes a meandering antenna conductor, and the portion of the meandering antenna conductor where the conductor is closely folded partially or entirely overlaps the ground pattern (refer to, for example, Japanese Laid-open Patent Publication No. 2002-314316). 
         [0012]    As illustrated in  FIG. 1C , the fixed casing  2  partially overlaps the movable casing  3  in the slide-type wireless terminal apparatus  1  in the casing-open state. When the case current (or image current) flows in the longitudinal direction of the casing, it is desirable that the current flowing in a board of the fixed casing  2  and the current flowing in a board of the movable casing  3  in the casing-open state are in phase, the currents flowing in the same direction as illustrated by the arrows in  FIG. 3A . 
         [0013]    However, in the 800 MHz frequency band, the current flowing in the board of the fixed casing  2  and the current flowing in the board of the movable casing  3  in the casing-open state are completely out of phase as illustrated by the arrows in  FIG. 3B . This degrades the transmission/reception characteristics in many cases. 
         [0014]    Effects that degrade the transmission/reception characteristics are reduced by increasing the distance between the fixed casing  2  and the movable casing  3 . However, since the size and the thickness of terminal apparatuses are being increasingly reduced, maintaining a large distance between the casings would decrease competitiveness of the products. 
       SUMMARY 
       [0015]    According to an aspect of an embodiment, a slide-type wireless terminal apparatus includes a first casing and a second casing slidable relative to the first casing. The wireless terminal apparatus includes a first circuit board which is provided in the first casing, an antenna which is provided in the first casing, a second circuit board which is provided in the second casing, a sliding member which is disposed between the first circuit board and the second circuit board, the sliding member including a portion which faces the antenna, the sliding member having electrical conductivity and being electrically connected to the first circuit board, and a guide member which is provided in the second casing, the guide member being for guiding the sliding member such that the sliding member slides relative to the guiding member. 
         [0016]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1A  is a plan view of an example of a slide-type wireless terminal apparatus. 
           [0019]      FIG. 1B  is a side view of the example of the slide-type wireless terminal apparatus. 
           [0020]      FIG. 1C  is a side view of the example of the slide-type wireless terminal apparatus. 
           [0021]      FIGS. 2A and 2B  are sectional views of the example of the slide-type wireless terminal apparatus in the casing-open state and the casing-closed state. 
           [0022]      FIGS. 3A and 3B  illustrate the phases of the currents flowing in a fixed casing and a movable casing. 
           [0023]      FIGS. 4A ,  4 B, and  4 C are respectively a perspective view, a plan view, and a side view of a slide-type wireless terminal apparatus according to an embodiment. 
           [0024]      FIGS. 5A ,  5 B, and  5 C are respectively a perspective view, a plan view, and a side view of the slide-type wireless terminal apparatus according to the embodiment. 
           [0025]      FIG. 6  is a sectional view of a slide-type wireless terminal apparatus according to a first embodiment. 
           [0026]      FIG. 7  is a plan view of a fixed casing of the slide-type wireless terminal apparatus according to the first embodiment. 
           [0027]      FIG. 8  is a sectional view of a slide-type wireless terminal apparatus according to a second embodiment. 
           [0028]      FIG. 9  is a plan view of a fixed casing seen from a front side. 
           [0029]      FIG. 10  is a plan view of the fixed casing illustrated in  FIG. 9  with a slide module removed. 
           [0030]      FIG. 11  is a plan view of the fixed casing with a rear half thereof removed seen from a front side. 
           [0031]      FIG. 12  is a plan view of the fixed casing illustrated in  FIG. 11  with a front half removed. 
           [0032]      FIG. 13  is a plan view of the fixed casing illustrated in  FIG. 11  with the front half removed. 
           [0033]      FIG. 14  is a frequency/VSWR characteristics graph of antennae. 
           [0034]      FIG. 15  is a sectional view of the slide-type wireless terminal apparatus according to a modification according to the second embodiment. 
           [0035]      FIGS. 16A and 16B  are plan views illustrating part of a circuit board. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0036]    Embodiments will be described below with reference to the drawings. 
         [0037]    Structure of Slide-Type Wireless Terminal Apparatus 
         [0038]      FIGS. 4A ,  4 B, and  4 C are respectively a perspective view, a plan view, and a side view of a slide-type wireless terminal apparatus in a casing-closed state according to an embodiment.  FIGS. 5A ,  5 B, and  5 C are respectively a perspective view, a plan view, and a side view of a slide-type wireless terminal apparatus in a casing-open state according to the embodiment. 
         [0039]    The slide-type wireless terminal apparatus according to the present embodiment includes a first casing and a second casing. Referring to  FIGS. 4A to 4C  and  5 A to  5 C, a slide-type wireless terminal apparatus  11  includes a fixed casing  12  as the first casing and a movable casing  13  as the second casing. The fixed casing  12  includes a front half  12   a,  a rear half  12   b,  and a first operation portion  15   a.  The fixed casing  12  houses a battery and an antenna. The movable casing  13  includes a front half  13   a,  a rear half  13   b,  a display portion  15   b,  and a second operation portion  15   c.    
       First Embodiment 
       [0040]      FIG. 6  illustrates a sectional view of the slide-type wireless terminal apparatus according to a first embodiment, and  FIG. 7  illustrates a plan view of a fixed casing  12  of the slide-type wireless terminal apparatus according to the first embodiment. 
         [0041]    In  FIG. 6 , the fixed casing  12  is provided with a slide module  17  formed of metal or the like on an outer side of the front half  12   a  that contacts the movable casing  13 , and the movable casing  13  is provided with a rail plate  18  in the rear half  13   b  that contacts the fixed casing  12 . The fixed casing  12  houses a circuit board  20  therein, and the movable casing  13  houses a circuit board  24  therein. The slide module  17  of the fixed casing  12  is engaged with the rail plate  18  of the movable casing  13  so as to allow the movable casing  13  to slide. Thus, the state of the slide-type wireless terminal apparatus  11  changes from the casing-open state to the casing-closed state, and from the casing-closed state to the casing-open state. 
         [0042]    Referring to  FIGS. 6 and 7 , in the fixed casing  12 , the distal end of the slide module  17  extends to the position of an antenna  14  in a Y 1  direction, which is the longitudinal direction of the casing. The antenna  14  and the slide module  17  are disposed between the fixed casing  12  and the movable casing  13  such that the slide module  17  partially or entirely opposes the antenna  14  in a Z 1  direction, which is a thickness direction of the casing. The slide module  17  is connected to a ground wiring pattern of the circuit board  20  that is housed in the fixed casing  12  using connecting members  19  such as metal screws. 
         [0043]    A metal component of the fixed casing  12  disposed closest to the movable casing  13  is the slide module  17 . The phases of the case current (or image currents) flowing in the circuit board  20  in the fixed casing  12  and the current flowing in the circuit board  24  in the movable casing  13  are determined in accordance with a positional relationship between the slide module  17  and the circuit board  24  housed in the movable casing  13 , and the area of the slide module  17 . 
         [0044]    The slide module  17  is an example of, for example, a sliding member, and the rail plate  18  is an example of, for example, a guide member. 
         [0045]    In a structure illustrated in  FIG. 2 , the distal end of the slide module  7  does not extend to the antenna  4  position so as not to cause the slide module  7  to oppose the antenna  4  in the Z direction, thereby decreasing electromagnetic coupling between the slide module  7  and a circuit board in the movable casing  3 . 
         [0046]    In contrast, according to the present embodiment, the slide module  17  partially opposes the antenna  14  and is connected to the ground wiring pattern of the circuit board  20  so as to be electromagnetically coupled to the antenna  14 . By feeding the power from the antenna  14  to the slide module  17  and the ground wiring pattern of the circuit board  20  by voltage feeding, a new resonance is generated. By changing the amount of coupling between the slide module  17  and the antenna  14 , and by changing the area of the slide module  17 , the frequency of the resonance is adjusted so as to generate a new resonance at a desired frequency. The above-described new resonance causes the current flowing in the circuit board  20  of the fixed casing  12  and the current flowing in the circuit board  24  of the movable casing  13  in the casing-open state to be in phase. 
         [0047]    At this time, the area in which the antenna  14  and the slide module  17  oppose each other is an important parameter. As the area in which the antenna  14  and the slide module  17  oppose each other increases, the amount of electromagnetic coupling increases and the characteristics in the casing-open state is improved. However, when the amount of electromagnetic coupling excessively increases, the characteristics in the casing-closed state degrade. This is because the slide module  17  would function as the ground in the casing-closed state. For this reason, the amount of coupling is determined such that desirable characteristics can be obtained in both of the casing-open state and the casing-closed state. In addition, the resonance frequency can be adjusted also by changing the positions of the connecting members  19  in the Y 1  direction. 
       Second Embodiment 
       [0048]      FIG. 8  illustrates a sectional view of the slide-type wireless terminal apparatus including the first casing and the second casing according to a second embodiment. 
         [0049]    In  FIG. 8 , the fixed casing  12  as the first casing is provided with copper tape  21  on the outer side of the front half  12   a  that contacts the movable casing  13  as the second casing. The fixed casing  12  is also provided with a metal slide module  22 . The copper tape  21  is electrically connected to the slide module  22 . The fixed casing  12  houses the circuit board  20  therein, and the movable casing  13  houses the circuit board  24  therein. 
         [0050]    The movable casing  13  is provided with the rail plate  18  in the rear half  13   b  that contacts the fixed casing  12 . The slide module  22  of the fixed casing  12  is engaged with the rail plate  18  of the movable casing  13  so as to allow the movable casing  13  to slide. Thus, the state of the slide-type wireless terminal apparatus  11  changes from the casing-open state to the casing-closed state, and from the casing-closed state to the casing-open state. 
         [0051]    In the fixed casing  12 , the distal end of the copper tape  21 , which is connected to the slide module  22 , extends to the antenna  14  position in the Y 1  direction, which is the longitudinal direction of the casing. The antenna  14  and the copper tape  21  are disposed between the fixed casing  12  and the movable casing  13  such that the copper tape  21  partially or entirely opposes the antenna  14  in the Z 1  direction. The slide module  22  is connected to the ground wiring pattern of the circuit board  20  that is housed in the fixed casing  12  using the connecting members  19  such as metal screws. Here, the copper tape  21  corresponds to, for example, electrically conductive tape. 
         [0052]    In the first embodiment, the size of the slide module  17  is adjusted. However, the adjustment of the size of the slide module  17  is difficult in application because of strength restrictions. For this reason, in the second embodiment, the copper tape  21  is added as a separate metal component and connected to the slide module  22  so as to electrically increase the size of the slide module  17 . The size of the copper tape  21  can be desirably changed, thereby increasing versatility in design. Also in the second embodiment, the resonance frequency can be adjusted also by changing the positions of the connecting members  19  in the Y 1  direction. 
         [0053]    Details of Second Embodiment 
         [0054]      FIG. 9  is a plan view of the fixed casing  12  seen from the front side (arrow Z 1  direction in  FIG. 5C ). 
         [0055]    In  FIG. 9 , the copper tape  21  is attached to the outer surface of the front half  12   a.  The metal slide module  22  is provided at a position in which the slide module  22  opposes part of the copper tape  21  and connected to the copper tape  21 . The slide module  22  is secured to the front half  12   a  with screws. 
         [0056]      FIG. 10  is a plan view of the fixed casing  12  illustrated in  FIG. 9  with the slide module  22  removed. In  FIG. 10 , the copper tape  21  has a protrusion  21   b  so as to extend from a rectangular main body  21   a  in the arrow Y 2  direction, which is the longitudinal direction of the casing. The main body  21   a  of the copper tape  21  is attached to the front half  12   a,  and the protrusion  21   b  of the copper tape  21  is bonded to the slide module  22  so as to electrically connect the copper tape  21  to the slide module  22 . Alternatively, the copper tape  21  may be attached to an inner surface of the front half  12   a.  In this case, the copper tape  21  is electrically connected to the slide module  22  with metal screws or the like that secure the slide module  22  to the front half  12   a.    
         [0057]    The front half  12   a  has grooves  23   a  and  23   b  formed therein. Part of legs  22   a  and  22   b  of the slide module  22  are respectively engaged with the grooves  23   a  and  23   b  so as to be positioned in the grooves  23   a  and  23   b.  Thus, the slide module  22  is secured to the front half  12   a.    
         [0058]      FIG. 11  is a plan view of the fixed casing  12  with the rear half  12   b  removed seen from the rear side (arrow Z 2  direction in  FIG. 5C ). 
         [0059]    In  FIG. 11 , an antenna  25  for the  800  MHz band is disposed in an upper edge portion of the fixed casing  12  and secured to the front half  12   a.  The antenna  25  corresponds to the antenna  14  illustrated in  FIGS. 6 to 8 . An antenna  26  for the  2  GHz band is disposed in an upper side of a right edge portion of the fixed casing  12  and secured to the front half  12   a.  A secondary battery  27  is disposed in a portion below the center of the fixed casing  12 . 
         [0060]      FIGS. 12 and 13  are plan views illustrating the fixed casing  12  illustrated in  FIG. 11  with the front half  12   a  and part of the circuit board  20  removed. In FIGS.  12  and  13 , the copper tape  21  and the slide module  22  are visible because of the removal of the front half  12   a.    
         [0061]    In  FIG. 12 , the length of the main body  21   a  of the copper tape  21  in the length direction, that is, in the longitudinal direction of the casing is set to Ya. An upper portion of the main body  21   a  of the copper tape  21  is set to oppose part of the antenna  25 . In  FIG. 13 , the length of the main body  21   a  of the copper tape  21  in the length direction is set to Yb (Yb&gt;Ya). An upper portion of the main body  21   a  of the copper tape  21  is set to oppose substantially entire portion of the antenna  25  in the longitudinal direction of the casing. Although the circuit board  20  is partially removed from  FIGS. 12 and 13 , for example, metal screws screwed through screw holes  28   a  and  28   b  secure the slide module  22  to the front half  12   a  and connect the slide module  22  to the ground wiring pattern of the circuit board  20 . 
         [0062]    Thus, the amount of electromagnetic coupling between the antenna  25  and the copper tape  21  can be adjusted by changing the length of the main body  21   a  of the copper tape  21  in the length direction. The amount of electromagnetic coupling between the antenna  25  and the copper tape  21  can also be adjusted by changing the length of the main body  21   a  of the copper tape  21  in the lateral direction. 
         [0063]    Referring to  FIG. 14 , frequency/voltage standing wave ratio (VSWR) characteristics of the antenna  25  in the casing-open state in the embodiment illustrated in  FIGS. 9 to 12  are indicated by a solid line. The dashed line indicates frequency/VSWR characteristics of the antenna  4  of the related art slide-type wireless terminal apparatus in the casing-open state. According to the characteristics of the present embodiment indicated by the solid line, a new resonance is generated with a frequency of about 800 MHz and the frequency VSWR/characteristics are improved around 800 MHz. 
         [0064]    Modification of Second Embodiment 
         [0065]      FIG. 15  is a sectional view of the slide-type wireless terminal apparatus according to a modification of the second embodiment. 
         [0066]    In  FIG. 15 , the fixed casing  12  is provided with the copper tape  21  on the outer side of the front half  12   a  that contacts the movable casing  13 . The fixed casing  12  is also provided with the metal slide module  22 . The copper tape  21  and the slide module  22  are electrically connected to each other. In the fixed casing  12 , the distal end of the copper tape  21 , which is connected to the slide module  22 , extends to the antenna  14  position in the Y 1  direction, which is the longitudinal direction of the casing. The antenna  14  and the copper tape  21  are disposed such that the copper tape  21  partially or entirely opposes the antenna  14  in the Z 1  direction. The slide module  22  is secured to the front half  12   a  with metal screws  31 . Connecting members  32 , which are metal springs or the like, connect the metal screws  31  to land patterns of the circuit board  20 . 
         [0067]      FIGS. 16A and 16B  are plan views illustrating part of the circuit board  20 .  FIG. 16A  illustrates one of land patterns  33  that are formed on a surface of the circuit board  20  opposing the front half  12   a.  One end of each connecting member  32  contacts the corresponding one of the land patterns  33 . Each land pattern  33  is connected to the ground wiring pattern (not illustrated). 
         [0068]    The amount of coupling that allows desirable characteristics to be obtained in both of the casing-open state and the casing-closed state is set by changing the shape of the slide module  17  or the copper tape  21  in the first or second embodiment. However, when such an amount cannot be set as in the first or second embodiment, an electronic component  35  illustrated in  FIG. 16B  is used. 
         [0069]      FIG. 16B  illustrates one of land patterns  34  that are formed on the surface of the circuit board  20  opposing the front half  12   a.  One end of each connecting member  32  contacts the corresponding one of the land patterns  34 . Each land pattern  34  is connected to a ground wiring pattern  36  with the electronic component  35  for adjusting a phase such as a capacitor or a coil therebetween. In this case, by adding inductance or capacitance of the electronic component  35 , the amount of coupling that allows desirable characteristics to be obtained in both of the casing-open state and the casing-closed state can be set. Here, the present embodiment is described as the modification of the second embodiment. However, it is clear that the first embodiment may use the structure as illustrated in  FIG. 16B . 
         [0070]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.