Patent Publication Number: US-2003228884-A1

Title: Two folding mobile telephone and mobile telephone

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a mobile telephone such as a two folding mobile telephone.  
       [0003] 2. Related Art of the Invention  
       [0004] In recent years, mobile telephones have been widely used as an information terminal having not only a talking function of a telephone but also an information communicating function using the Internet such as the access to a web site or use of an electronic mail.  
       [0005] Mobile telephones of this type usable as an information terminal require a display screen for displaying information as an image. To secure a large display screen and maintain the portability, a two folding type constituted by separately setting a display screen and keys for inputting data to two housings which can be collapsed is the mainstream as a present mobile telephone.  
       [0006] FIGS.  12 ( a ) to  12 ( c ) and FIGS.  13 ( a ) and  13 ( b ) show a conventional two folding mobile telephone (for example, see Japanese Patent Publication No. 2821333). As shown in FIGS. 12 and 13, a mobile telephone  1300  has a first housing  1310  with an input section  1311  such as a ten-key pad and the like set on its inside principal plane and a second housing  1320  with a display screen  1321  set on its inside principal plane.  
       [0007] A voice input plane  1312  having a built-in microphone for inputting voices is formed on the inside principal plane of the first housing  1310  in addition to the input section  1311  and moreover, hinge brackets  1313   a  and  1313   b  to be rotatably connected with the second housing are set to positions opposite to the voice input plane  1312  at the both sides of the input section  1311 . Moreover, a retractable helical antenna  1314  is set nearby the outside principal plane of the first housing  1310  and an grounding plate  1315  for earthing various sections of internal circuits of the mobile telephone is built in the first housing  1310 . The position in which the grounding plate  1315  is built is a position at which the thickness of the first housing is substantially halved.  
       [0008] Furthermore, a voice output plane  1322  storing a loudspeaker for outputting voices is set to the inside principal plane of the second housing  1320  in addition to the display screen  1321  and a hinge arm  1323  for rotatably connecting the second housing  1320  with the first housing  1310  is set at an end portion of the second housing  1320  opposite to the voice output plane  1322  at the side of the display screen  1321 .  
       [0009] As shown in FIGS. 12 and 13, the first housing  1310  and the second housing  1320  are connected each other because the hinge arm  1323  is fitted between the hinge brackets  1313   a  and  1313   b  and rotatably movable in the directions of the arrows in FIGS. 12 and 13. In this case, when the first housing  1310  with the hinge arm set on it rotates up to a predetermined angle, the rotation of the housing  1310  is stopped by a stopper  1316  formed at an end of the rotating first housing  1310 .  
       [0010] As shown in FIGS.  13 ( a ) and  13 ( b ), when the above two folding mobile telephone  1300  is not operated, it is possible to collapse the telephone  1300  so that the inside principal planes of the both housings are faced each other. Thus, the portability is improved and a large display screen can be secured.  
       [0011] Though not illustrated, holding means of holding the angle of aperture formed between the first housing  1310  and second housing  1320  at a specific angle by an energizing force using a spring is set in the hinge brackets  1313   a  and  1313   b  and the hinge arm  1323  and the specific angle is applied to the collapsed state shown in FIG. 13( a ) and the operating state shown in FIG. 12 ( a ). Furthermore, the entire disclosure of Japan Patent No. 2821333 are incorporated herein by reference in its entirety.  
       [0012] The above two folding mobile telephone is further decreased in thickness and size in order to further improve its portability.  
       [0013] However, the above two folding mobile telephone has the following problems.  
       [0014] When operating a mobile telephone, a user talks by bringing the mobile telephone nearby his head so that the voice output plane comes nearby his ear and the voice input plane nearby this mouth. FIG. 14( a ) is an illustration schematically showing a positional relation between each portion of a mobile telephone when operated and the head of a user.  
       [0015] As shown in FIG. 14( a ), when bringing the two folding mobile telephone  1300  nearby a head  1400 , various portions formed on the first housing  1310  and second housing  1320  also approach the head  1400 . Among these portions, a position of front ends of the grounding plate  1315  and helical antenna  1314  and the head  1400  greatly influence the gain of a two folding mobile telephone.  
       [0016] In FIG. 14( a ), distance A shows the distance from the front end of the helical antenna  1314  up to the head  1400 , distance B shows the distance from the grounding plate  1315  in the first housing up to the surface of the head  1400 , and distance C shows the average thickness of the second housing, and distance D shows the average thickness of the first housing. The angle of aperture formed between the first housing  1310  and the second housing  1320  is equal to 165° in the case of conventional examples 1 and 2. Therefore, the angle of depression “a” of the first housing  1310  to the second housing  1320  becomes 15° as shown in figure. Moreover, the arrow extending from the voice output plane  1322  shows the direction in which the directivity of an audio signal output from the voice output plane  1322  is maximized.  
       [0017]FIG. 14( b ) shows a relation between the thickness of the housing of a two folding mobile telephone, the distance between the phase center C p  between the grounding plate  1315  and the helical antenna  1314  minimized in length, and the head  1400  on one hand and a gain loss on the other in the form of a table.  
       [0018] In the case of the conventional example 2, thicknesses of the first housing  1310  and second housing  1320  are smaller than the case of the conventional example 1. Moreover, the distance A from the front end of the helical antenna  1314  up to the surface of the head  1400  and the distance B from the grounding plate  1315  up to the surface of the head  1400  in the case of the conventional example 2 are smaller than the case of the conventional example 1. That is, front ends of the grounding plate and antenna built in a housing in the case of the conventional example 2 having a housing thinner than that of the conventional example 1 are closer to a head compared to the case of the conventional example 1.  
       [0019] In this case, a mobile telephone has a problem that when an antenna approaches a human body, the gain loss for transmission or reception increases.  
       [0020] In the case of the example shown in FIG. 14( b ), the conventional example 2 produces the total gain loss of approx. −2.0 dB including the gain loss α caused by the helical antenna  1314  and the gain loss β caused by the grounding plate  1315  on the basis of the conventional example 1. That is, decrease of a housing in thickness causes reception gain to decrease.  
       SUMMARY OF THE INVENTION  
       [0021] The present invention is made to solve the above problems and its object is to provide a two folding mobile telephone capable of reducing the attenuation of gain for reception even if a housing is decreased in size and thickness.  
       [0022] The 1 st  aspect of the present invention is a two folding mobile telephone comprising:  
       [0023] a first housing having an antenna, a built-in grounding plate, and a hinge bracket set to an inside principal plane of said first housing;  
       [0024] a second housing having a hinge arm corresponding to said hinge bracket, which is set over at least an end portion, a display screen set to an inside principal plane to display information, and a voice output plane of a loudspeaker opposite to said hinge arm at the both sides of said display screen; and  
       [0025] a fixing mechanism of temporarily fixing said hinge bracket and said hinge arm; wherein,  
       [0026] said first housing and said second housing are connected so that their inside principal planes face each other when closed,  
       [0027] an angle of aperture formed between the inside of a virtual plane orthogonal to the direction when the directivity of an audio signal of said loudspeaker is maximized and the inside of a plane including said grounding plate is held at substantially 165° or larger by temporary fixing by said fixing mechanism, and  
       [0028] said virtual plane is substantially the same as or parallel with a plane including the voice output plane of said loudspeaker and said display screen for displaying information.  
       [0029] The 2 nd  aspect of the present invention is the two folding mobile telephone according to the 1 st  aspect, where in,  
       [0030] said fixing mechanism has a stopper set to said first housing and/or said second housing and elastic holding means of holding so that said angle of aperture is held constant by an elastic force,  
       [0031] said elastic holding means provides an energizing force for said angle of aperture to tend to a predetermined first angle,  
       [0032] said stopper is set so that said angle of aperture becomes a second angle smaller than said first angle, and  
       [0033] said second angle is an angle equal to or smaller than a first limit angle at which an allowance accompanying holding by the energizing force of said elastic holding means cannot be permitted.  
       [0034] The 3 rd  aspect of the present invention is the two folding mobile telephone according to the 1 st  aspect, wherein,  
       [0035] said fixing mechanism has elastic holding means for holding so that said angle of aperture is kept constant by an elastic force, and  
       [0036] said angle of aperture is equal to or smaller than a second limit angle at which said angle of aperture can be held by said elastic holding means.  
       [0037] The 4 th  aspect of the present invention is the two folding mobile telephone according to the 1 st  aspect, wherein,  
       [0038] said angle of aperture kept by said temporary fixing substantially 166° or larger and 172° or smaller at which said angle of aperture can be held by said temporary fixing.  
       [0039] The 5 th  aspect of the present invention is the two folding mobile telephone according to the 1 st  aspect, wherein,  
       [0040] the inside principal plane of said first housing and the inside principal plane of said second housing have a step when the inside principal plane of said first housing and the inside principal plane of said second housing open so that the angle formed between the inside principal planes of them becomes substantially 180°, and  
       [0041] the inside principal plane of said first housing retreats toward the inside of the housing from the inside principal plane of said second housing.  
       [0042] The 6 th  aspect of the present invention is the two folding mobile telephone according to the 1 st  aspect, wherein,  
       [0043] the average distance between the inside principal plane of said first housing and the outside principal plane opposite to the inside principal plane of said first housing is equal to substantially 7 mm and the average distance between the inside principal plane of said second housing and the outside principal plane opposite to the inside principal plane of said second housing is equal to substantially 9.8 mm.  
       [0044] The 7 th  aspect of the present invention is a two folding mobile telephone comprising:  
       [0045] a first housing having an antenna, a built-in grounding plate, and a hinge bracket set to the inside principal plane of said first housing;  
       [0046] a second housing having a hinge arm corresponding to said hinge bracket, which is provided over at least an end portion, a display screen set to an inside principal plane to display information, and a voice output plane of a loudspeaker opposite to the hinge arm at the both sides of said display screen; and  
       [0047] a fixing mechanism of temporarily fixing said hinge bracket and said hinge arm; wherein,  
       [0048] said first housing and said second housing are connected so that their inside principal planes face each other when closed,  
       [0049] a virtual plane orthogonal to a direction when the directivity of an audio signal of said loudspeaker is maximized tilts from a plane including said display screen, and  
       [0050] a direction of said tilt is in a direction in which the direction when the directivity of the audio signal of said loudspeaker is maximized and said display screen form an obtuse angle.  
       [0051] The 8 th  aspect of the present invention is a mobile telephone comprising:  
       [0052] a housing having an antenna, a built-in grounding plate, a display screen set to an inside principal plane to display information, and the voice output plane of a loudspeaker, wherein,  
       [0053] a virtual plane orthogonal to a direction in which the directivity of an audio signal of said loudspeaker is maximized tilts from a plane including said display screen, and  
       [0054] a direction of tilt is in a direction in which a direction when the directivity of the audio signal of said loudspeaker is maximized and said display screen form an obtuse angle.  
       [0055] The 9 th  aspect of the present invention is the two folding mobile telephone according to the 7 th  aspect, wherein,  
       [0056] said virtual plane is formed as said voice output plane on the inside principal plane of said first housing.  
       [0057] The 10 th  aspect of the present invention is a two folding mobile telephone comprising:  
       [0058] a first housing having a built-in grounding plate and a hinge bracket set on an inside principal plane of said first housing;  
       [0059] a second housing having a hinge arm corresponding to said hinge bracket, provided over at least an end portion, a display screen set to an inside principal plane to display information, a voice output plane of a loudspeaker opposite to said hinge arm at the both sides of said display screen, an antenna; and  
       [0060] a fixing mechanism of temporarily fixing said hinge bracket and said hinge arm; wherein,  
       [0061] said first housing and said second housing are connected so that the housings are faced each other and closed,  
       [0062] an angle of aperture formed between the inside of a virtual plane orthogonal to a direction in which the directivity of the audio signal of said loudspeaker is maximized and the inside of the plane including said grounding plate is held at substantially 165° or larger by temporary fixing by said fixing mechanism, and  
       [0063] said virtual plane is substantially the same as or parallel with a plane including the voice output plane of said loudspeaker and the display screen for displaying information.  
       [0064] The 11 th  aspect of the present invention is a two folding mobile telephone comprising:  
       [0065] a first housing having a hinge bracket set to an inside principal plane of said first housing and an antenna;  
       [0066] a second housing having a hinge arm corresponding to said hinge bracket, which is set over at least an end portion, a display screen set to an inside principal plane to display information, a voice output plane of a loudspeaker opposite to said hinge arm at the both sides of said display screen, and a built-in grounding plate; and  
       [0067] a fixing mechanism of temporarily fixing said hinge bracket and said hinge arm; whrein,  
       [0068] said first housing and said second housing are connected so that the inside principal planes of said housings are faced each other and closed,  
       [0069] an angle of aperture formed between the inside of a virtual plane orthogonal to a direction in which the directivity of the audio signal of said loudspeaker is maximized and the inside of a plane including said grounding plate is held at substantially 165° or larger by temporary fixing by said fixing mechanism, and  
       [0070] said virtual plane is substantially the same as or parallel with a plane including the voice output plane of said loudspeaker and said display screen for displaying information. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0071]FIG. 1( a ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0072]FIG. 1( b ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0073]FIG. 1( c ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0074]FIG. 2( a ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0075]FIG. 2( b ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0076]FIG. 2( c ) is a block diagram of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0077]FIG. 3( a ) is an illustration schematically showing a positional relation between each section of the two folding mobile telephone of the embodiment 1 of the present invention when operated and the head of a user;  
     [0078]FIG. 3( b ) is an illustration showing a table of comparison between gain losses of the two folding mobile telephone of the embodiment 1 of the present invention and a conventional example;  
     [0079]FIG. 4( a ) is an illustration schematically showing a configuration of elastic holding means of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0080]FIG. 4( b ) is an illustration schematically showing a configuration of elastic holding means of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0081]FIG. 4( c ) is an illustration schematically showing a configuration of elastic holding means of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0082]FIG. 4( d ) is an illustration schematically showing a configuration of elastic holding means of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0083]FIG. 5 is an illustration for explaining operations of the elastic holding means of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0084]FIG. 6( a ) is an illustration showing an angle of aperture between housings of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0085]FIG. 6( b ) is an illustration showing an angle of aperture between housings of a conventional two folding mobile telephone;  
     [0086]FIG. 7( a ) is a block diagram of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0087]FIG. 7( b ) is a block diagram of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0088]FIG. 7( c ) is a block diagram of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0089]FIG. 8 is an illustration schematically showing a positional relation between each section of the two folding mobile telephone of the embodiment 2 of the present invention when operated and the head of a user;  
     [0090]FIG. 9( a ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0091]FIG. 9( b ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0092]FIG. 9( c ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 2 of the present invention;  
     [0093]FIG. 10( a ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0094]FIG. 10( b ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0095]FIG. 10( c ) is an illustration showing another configuration of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0096]FIG. 11( a ) is an illustration schematically showing a positional relation between each section of the two folding mobile telephone of the embodiment 1 of the present invention when operated and the head of a user;  
     [0097]FIG. 11( b ) is an illustration showing a table of comparison between gain losses of the two folding mobile telephone of the embodiment 1 of the present invention and a conventional example;  
     [0098]FIG. 12( a ) is a block diagram of a two folding mobile telephone of the prior art;  
     [0099]FIG. 12( b ) is a block diagram of a two folding mobile telephone of the prior art;  
     [0100]FIG. 12( c ) is a block diagram of a two folding mobile telephone of the prior art;  
     [0101]FIG. 13( a ) is a block diagram of a two folding mobile telephone of the prior art;  
     [0102]FIG. 13( b ) is a block diagram of a two folding mobile telephone of the prior art;  
     [0103]FIG. 14( a ) is an illustration schematically showing a positional relation between each section of a two folding mobile telephone of the prior art when operated and the head of a user;  
     [0104]FIG. 14( b ) is a table of comparison between gain losses of a two folding mobile telephone of the prior art;  
     [0105]FIG. 15 is an illustration showing a graph showing a relation between the angle of aperture between the first housing and second housing and the antenna gain of the two folding mobile telephone of the embodiment 1 of the present invention;  
     [0106]FIG. 16 is a block diagram of a mobile telephone of the second embodiment of the present invention;  
     [0107]FIG. 17 is an illustration showing a configuration of a loop antenna of an embodiment of the present invention;  
     [0108]FIG. 18 is an illustration showing another configuration of the present invention; and  
     [0109]FIG. 19 is an illustration showing another configuration of the present invention. 
    
    
     DESCRIPTION OF SYMBOLS  
     [0110] 100  Two folding mobile telephone  
     [0111] 110  First housing  
     [0112] 111  Input section  
     [0113] 112  Voice input plane  
     [0114] 113   a,    113   b  Hinge bracket  
     [0115] 114  Helical antenna  
     [0116] 115  Grounding plate  
     [0117] 116  Stopper  
     [0118] 120  Second housing  
     [0119] 121  Display screen  
     [0120] 122  Voice output plane  
     PREFERRED EMBODIMENTS OF THE INVENTION  
     [0121] Embodiments of the present invention are described below by referring to the accompanying drawings.  
     [0122] (Embodiment 1)  
     [0123] FIGS.  1 ( a ) to  1 ( c ) and FIGS.  2 ( a ) and  2 ( b ) are block diagrams of a two folding mobile telephone of an embodiment  1  of the present invention. As shown in FIGS. 1 and 2, the configuration of a two folding mobile telephone  100  is basically the same as that of the conventional example shown in FIGS. 12 and 13 and the two folding mobile telephone  100  has a first housing  110  with an input section including a ten-key pad set on its inside principal plane and a second housing  120  with a display screen  121  set on its inside principal plane.  
     [0124] A voice input plane  112  with a microphone for inputting voices set on it is formed on the inside principal plane of the first housing  110  in addition to an input section  111  and moreover, hinge brackets  113   a  and  113   b  to be rotatably connected with the second housing are set to positions opposite to the voice input plane  112  at the both sides of the input section  111  on the inside principal plane. Moreover, a retractable helical antenna  114  is set nearby the outside principal plane of the first housing and an grounding plate  115  for earthing various sections of internal circuits of a mobile telephone is built in the first housing. The position to which the earthing bottom bard  1145  is set is a position at which the thickness of the first housing is substantially halved.  
     [0125] Moreover, a voice output plane  122  with a loudspeaker set on it for outputting voices is formed on the inside principal plane of the second housing  120  in addition to the display screen  121  and a hinge arm  123  to be rotatably connected with the first housing is set to the position opposite to the voice output plane  122  at the both sides of the display screen  121  at an end portion of the second housing.  
     [0126] As shown in FIGS. 12 and 13, the first housing  110  and second housing  120  are connected each other because the hinge arm  123  is fitted between the hinge brackets  113   a  and  113   b  and rotatably movable in directions of the arrows in FIGS. 12 and 13. Though the hinge brackets  113   a  and  113   b  are set to the both ends of the hinge arm  123 , it is also allowed to divide the hinge arm  123  into two parts or more and set the hinge brackets  113   a  and  113   b  between the divided hinge arms. However, from the viewpoint of the strength of a hinge for holding an angle of aperture, it is preferable to use the illustrated structure.  
     [0127] In this case, the first housing  110  with the hinge arm set on it rotates up to a predetermined angle, it is stopped by a stopper  116  set to an end of the first housing  110 . Moreover, as shown in FIG. 2( c ) , when assuming that the stopper  116  is omitted and setting the angle of aperture formed between the first housing  110  and second housing to 180°, a configuration is realized in which the inside principal plane of the first housing  110  and that of the second housing  120  have a step d and the inside principal plane of the first housing retreats to the inward of the housing compared to the inside principal plane of the second housing  120  by the step d.  
     [0128] When the two folding mobile telephone  100  is not operated, it is possible to collapse the two folding mobile telephone  100  so that the inside principal planes of the both housings are faced each other as shown in FIG. 2 ( a ) and ( b ), improve the portability, and secure a large display screen using the most part of the inside principal plane of the second housing.  
     [0129] The two folding mobile telephone of this embodiment having the above configuration is characterized in that the angle of aperture formed between the first housing  110  and second housing  120  is made larger than the case of a conventional example. The effect of the large angle of aperture is described below.  
     [0130]FIG. 3( a ) is an illustration schematically showing a positional relation between each section of a two folding mobile telephone when operated and the head of a user. Because the correspondence of symbols showing distances and dimensions is the same as the case of the conventional example shown in FIG. 14 ( a ) , detailed description is omitted. However, the angle of aperture formed between the first housing  110  and second housing shown in FIG. 3 ( a ) is equal to 168° in the case of this embodiment and therefore, the angle of depression “a” of the first housing  110  to the second housing  120  becomes 12°.  
     [0131]FIG. 3( b ) shows a relation between the thickness of the housing of a two folding mobile telephone, distances between the grounding plate  115 , the front end of the helical antenna  114  minimized in length, and the head  300  on one hand and a gain loss on the other as a comparison table between this embodiment and the conventional example in FIG. 14( b ).  
     [0132] As shown in the table, because the embodiment 1 and the conventional example 2 have housings of the same dimensions, the distance C and distance D are equal to each other. However, because the angle of aperture between the first housing  110  and second housing  120  of this embodiment is larger than the case of the conventional example 2 by 3°, the distance A becomes smaller than the case of the conventional example 2 but the distance B becomes larger than the case of the conventional example 2.  
     [0133] Therefore, as shown in the table, the gain loss α due to the distance A from the front end of the helical antenna  114  up to the surface of the head  300  slightly increases. However, the reduction of the gain loss β due to the distance B from the grounding plate  115  up to the surface of the head  300  increases and the increase of the gain loss β is sufficiently compensated. Therefore, the gain loss is decreased as a whole.  
     [0134] However, when further increasing the angle of aperture between the first housing  110  and the second housing, the distance A decreases and the gain loss α due to the distance A further increases. However, because the reduction amount of the gain loss α due to the increase of the distance B approaches a saturated state, the gain loss increases as a whole. Therefore, it is preferable to realize an angle of aperture so that the relation between the distances A and B is optimized.  
     [0135]FIG. 15 shows a relation between the angle of aperture between the first housing  110  and second housing  120  and influences of the helical antenna  114  and grounding plate  115  on a reception gain in the form of a graph in detail. As shown by the broken line A in FIG. 15, when the angle of aperture between the first housing  110  and second housing  120  increases, an single antenna moves only in the direction of approaching the head  300  and thereby, the gain of the antenna reduces. The inclination of the reduction increases as an angle of aperture increases, for example, by −0.3 dB for 1° when an angle of aperture is smaller than substantially 168°, −0.5 dB for 1° when an angle of aperture ranges substantially between 168° and 170°, −0.7 dB for 1° when an angle of aperture ranges between 170° and 172°, and −1.0 dB for 1° when an angle of aperture is larger than 172°.  
     [0136] However, as shown by the broken line B, when an angle of aperture is approx. 165° the same as the case of a conventional example, the gain of an antenna increases as an angle increases and the grounding plate  115  provides an inclination of monotone increase (+1.0 dB for 1°) until the angle of aperture becomes 168°. Moreover, an increasing trend is maintained substantially up to 168° to 170° but the inclination is moderated (+0.5 dB for 1°) and further moderated in the range of substantially 170° to 172° (+0.2 dB for 1°) to increase an antenna gain, and a saturated state is realized (inclination of 0) when the angle of aperture becomes 172° or more.  
     [0137] As described above, by making the angle of aperture between the first housing  110  and second housing  120  larger than 165° which is conventionally known, the attenuation of a gain due to the fact that an antenna approaches the head  300  is compensated by the increase of a gain due to the fact that the grounding plate  115  is spaced away from the head  300 . Therefore, it is found that the total gain is monotone-increased up to an angle of aperture of substantially 168°. Moreover, it is possible to keep the peak up to at least 170°.  
     [0138] Therefore, by setting the angle of aperture between the first housing  110  and second housing  120  to a value larger than the case of a conventional example and ideally setting a range of 168° substantially to 170° or substantially setting a range of at least 166° to 172° as an optimum angle, it is possible to sufficiently increase an antenna gain.  
     [0139] Then, a mechanism for keeping the angle of aperture between the first housing  110  and second housing  120  at a value larger than the case of a conventional example is described below.  
     [0140] This embodiment also includes elastic holding means of holding the angle of aperture between the first housing  110  and second housing  120  at a specific angle in a collapsed state or operating state by an energizing force using a spring or the like in the hinge brackets  113   a  and  113   b  and the hinge arm  123  the same as the case of a conventional example.  
     [0141]FIG. 4( a ) schematically shows a configuration of elastic holding means. The elastic holding means is constituted by a spring portion fixed in the hinge bracket  113   a  or  113   b  and a support portion fixed in the hinge arm  123 . The spring portion has a hollow helical spring  401  with a predetermined length and hollow sliding members  402   a  and  402   b  connected to the both ends of the helical spring  401  and a support body  411  of the support portion is built in the hollow portion. In FIG. 4 ( a ), the support body  411  is schematically locally cut off so that description is understandable.  
     [0142] The support portion has the support body  411  in which the spring portion is set and end members  412   a  and  412   b  set to the both ends of the support body  411 . Because an elastic force works on the helical spring  401  in the direction in which the length increases, an energizing force is applied to the sliding members  402   a  and  402   b  in the direction in which the members are separate from each other (arrows in FIG. 4( a )) and thereby the end member  412   a  contacts with the sliding member  402   a  and the end member  412   b  contacts with the sliding member  402   b.  Therefore, by opening or closing the first housing  110  and second housing  120  of the two folding mobile telephone  100 , the spring portion fixed to the first housing  110  rotates around the shaft of the support body  411 .  
     [0143] Moreover, in the case of the sliding member  402   a  and end member  412   a , predetermined concave and convex shapes corresponding to each other are formed on face opposite to each other. FIG. 4 ( a ) shows the shape of the sliding member  402   a  and FIG. 4( b ) shows the shape of the end member  412   a.  The sliding member  402   a  has a convex portion  403  on its principal plane and the end member  412   a  has a concave portion  413  corresponding to the convex portion  403  on its principal plane.  
     [0144] As shown in FIG. 4( c ), when the first housing  110  and the second housing  120  are opened or closed, the sliding member  402   a  rotates around the main-shaft body  411  while the convex portion  403  contacts with the principal plane of the end member  412   a.  When the end member  412   a  rotates up to a certain extent, the convex portion  403  and concave portion  413  are faced each other, the convex portion  403  is fitted into the concave portion  413  by the energizing force of the helical spring  401  as shown in FIG. 4( d ), and the spring portion and support portion are fixed to each other. The vicinity of the fixing position serves as the angle of aperture between the first housing  110  and second housing  120  (corresponding to a predetermined first angle of the present invention). However, because accuracies of the convex portion  403  and concave portion  413  are not very strict but the so-called allowance is provided for them, a tolerance is produced in an angle of aperture even if the convex portion  403  is fitted into the concave portion  423 .  
     [0145] This represents that it is impossible to temporarily fix the angle of aperture between the first housing  110  and second housing  120  by only the holding force of the elastic holding means. Therefore, the angle of aperture is temporarily fixed by the energizing force of the elastic holding means and the drag from the stopper  116  by using the stopper  116  of the first housing  110 .  
     [0146]FIG. 5 is an illustration for explaining a condition for temporarily fixing the angle of aperture between the first housing  110  and second housing  120  of the two folding mobile telephone  100 .  
     [0147] As shown in FIG. 5, when spreading the first housing  110  and second housing  120 , the convex portion  403  of the sliding member  402   a  of the spring portion moves on the principal plane of the end member  412   a  in the direction of being fitted into the concave portion  413  and a force is applied in the direction of being further fitted into the concave potion  413  by the energizing force from the helical spring  401 . Therefore, when the convex portion  403  is present in an area “a” which is a slope on the concave portion  413 , a force is applied to the convex portion  403  in the direction in which the angle of aperture θ between the first housing  110  and second housing  120  increases. Moreover, when the convex portion  403  is present in an area “b” which is the bottom of the concave portion  413 , a force is applied in the direction of being fixed to the concave portion  413 . Furthermore, when the convex portion  403  is present in an area “c” which is the slope of the concave portion  413 , a force is applied in the direction in which the angle of aperture θ between the first housing  110  and second housing  120  decreases.  
     [0148] In this case, as shown in FIG. 6( a ), the first housing  110  is stably fixed by the energizing force of the spring portion and the drag as a counteraction of the energizing force received from the stopper  116  by setting the stopper  116  so as to correspond to a first limit angle obtained by assuming the angle of aperture between the first housing  110  and second housing  120  when the convex portion  403  is present in the area “a” as the fist limit angle, that is, as an angle at which the allowance due to holding by the energizing force of the elastic holding means cannot be allowed.  
     [0149] As shown in FIG. 5, the area “a” where an energizing force works in the direction in which the angle of aperture θ between the first housing  110  and second housing  120  increases has a predetermined width. In the case of a conventional example, however, the stopper  116  is set so as to be θ=165° as shown (A) in FIG. 5 because of a human-engineering reason.  
     [0150] In the case of this embodiment, however, the stopper  116  is set to a potion at which θ decided as the first limit angle further increases in order to obtain optimum conditions of the antenna and grounding plate shown in FIG. 15 by separating the grounding plate  115  built in the first housing  110  from the head of a user and θ is set to, for example, 168° as shown (B) in FIG. 5 to obtain the results shown in FIG. 3.  
     [0151] Though it is possible to increase the angle of aperture θ as long as the position of the convex portion  403  is mechanically present in the area “a” in FIG. 5, it is impossible to exceed the second limit angle at which holding can be made by the elastic holding means. Therefore, it is most preferable to set 170° which is a limit angle of aperture for proving an optimum antenna gain or an angle of approx. 172° when considering a tolerance to θ as the above second limit angle.  
     [0152] Moreover, when setting θ to such an extremely large value as the phase center C p  of the helical antenna  114  comes above the rotational center of a hinge, the phase center C p  approaches the display screen  121  and the radiation from the antenna may adversely affect screen display.  
     [0153] Moreover, particularly when θ exceeds substantially 180°, a two folding mobile telephone bends backward as a whole and thereby, a trouble occurs that the two folding mobile telephone cannot be easily handled. Therefore, it is not preferable to set θ to an angle larger than substantially 180°.  
     [0154] In the above description, the angle of aperture θ corresponds to an angle of aperture formed between the inside of a virtual plane orthogonal to a direction in which the directivity of an audio signal of a loudspeaker of the present invention is maximized and the inside of a plane including an grounding plate.  
     [0155] Moreover, it is allowed to form this embodiment so as to have the constitution shown in FIGS.  10 ( a ) to  10 ( c ).  
     [0156] FIGS.  10 ( a ) to  10 ( c ) are block diagrams of another example of the two folding mobile telephone of the embodiment 1. As shown in FIGS.  10 ( a ) to  10 ( c ), for the constitution of the two folding mobile telephone  1000 , a portion same as or corresponding to that in FIG. 1 is provided with the same symbol and its detailed description is omitted. Moreover, a raised portion  1010  formed because a part of the helical antenna  114  is slightly raised is present on the outside principal plane located at the opposite side of the inside principal plane of the first housing  110  to the grounding plate  115 . The raised portion  1010  is formed by setting the helical antenna  114  to a position nearby the outside principal plane compared to the case of a conventional example.  
     [0157] The two folding mobile telephone having the above configuration is different in that the helical antenna  114  is set more nearby the outside principal plane by a value equivalent to the raised portion  1010  though the angle of aperture between the first housing  110  and second housing  120  is the same as the case of the configuration shown in FIG. 1.  
     [0158]FIG. 11( a ) is an illustration schematically showing a positional relation between each section of the two folding mobile telephone of this embodiment when operated in another configuration and the head of a user. Because the correspondence of each symbol showing a distance or dimension is the same as the case of the conventional example shown in FIG. 14( a ) , detailed description of the symbol is omitted. Moreover, the angle of aperture formed between the first housing  110  and second housing  120  is substantially 168° and the angle of depression of the first housing  110  to the second housing  120  shown in FIG. 11( a ) is substantially 12°.  
     [0159]FIG. 11( b ) shows relations between the thickness of the housing of a two folding mobile telephone, the distance between the grounding plate  115  the front end of the helical antenna  114  and the head  300 , and a gain loss as a table of comparison between the configuration in FIG. 1 and the conventional example 2 in FIG. 14( b ).  
     [0160] As shown in the table, because this embodiment and the conventional example 2 respectively have a housing of substantially the same dimension, the distance C and distance D are equal to each other. However, the angle of aperture formed between the first housing  110  and second housing is 168° which is the same as the case of the embodiment 1 and the distance A between the front end of the helical antenna  114  and the head  300  becomes larger than the cases of the conventional example 2 and the embodiment 1 because the raised portion  1010  is formed as shown in FIG. 11 ( a ). The table shows an example in which the distance A is set to a value 0.4 mm larger than the case of the embodiment 1.  
     [0161] Therefore, it is possible to further reduce the gain loss α due to the distance A from the helical antenna  114  up to the surface of the head  300  compared to the case of the embodiment 1 and reduce the whole gain loss.  
     [0162] Also in the case of a conventional example, it is known that the distance between an antenna and the body of a user is maximized by, for example, setting the antenna so that it greatly rises from the surface of a housing including the antenna.  
     [0163] However, when setting the antenna so that it greatly rises from the surface of the housing in order to reduce the gain loss due to decrease of the housing in thickness and mounting the housing on the ground or a table, the housing may be mounted in an unstable state due to a part of the housing and the antenna or a user may feel uncomfortable when grasping the housing by his hand.  
     [0164] Therefore, it is more preferable to minimize the height of the raised portion  1010  from the outside principal plane of the portion  1010  because the portion  1010  does not interrupt taking-in/out when housed or does not make a user feel uncomfortable.  
     [0165] Thus, according to this embodiment, because the angle of aperture between housings is increased than ever, it is possible to obtain an optimum condition for reducing an antenna gain loss due to decrease of a mobile telephone in thickness by keeping an grounding plate from a head while making an antenna approach a human body.  
     [0166] A setting position of the antenna  114  is not restricted to the position shown in FIG. 1. It is allowed to set the antenna to any position as long as the position becomes more distant from a human body when increasing the angle of aperture between the housing  110  and second housing  120 .  
     [0167] (Embodiment 2)  
     [0168] FIGS.  7 ( a ) to  7 ( c ) are block diagrams of a two folding mobile telephone of an embodiment 2 of the present invention. As shown in FIGS.  7  ( a ) to  7  ( c ), a portion of the configuration of a two folding mobile telephone  700  same as or corresponding to that in FIG. 1 is provided with the same symbol and its detailed description is omitted.  
     [0169] Moreover, on the inside principal plane of a second housing  120 , a partial plane including a voice output plane  122  forms a slope  701  tilted from a plane on which a display screen  121  is formed at a predetermined angle φ.  
     [0170] The two folding mobile telephone of this embodiment having the above configuration is different from a conventional example in that a slope  701  is formed though the angle of aperture between a first housing  110  and the second housing  120  is the same as the case of the conventional example. Advantages of the embodiment 2 are described below.  
     [0171]FIG. 8 is an illustration schematically showing a relation between each section of a two folding mobile telephone while operated and the head of a user. Because the correspondence of each symbol showing a distance or dimension is the same as the case of the conventional example shown in FIG. 14( a ), detailed description is omitted. Moreover, the angle of aperture formed between the first housing  110  and second housing  120  is substantially 165° which is the same as the case of the conventional example and the angle of depression “a” of the first housing  110  to the second housing  120  shown in FIG. 8 is 15°.  
     [0172] Moreover, in the case of the two folding mobile telephone  700  of this embodiment, the position of an ear of a head  300  and the slope  701  of the second housing  120  are held while they are faced each other substantially in parallel. In the case of the conventional example, the position of the head  300  and the whole inside principal plane of the second housing  120  are held while they are faced each other substantially in parallel (refer to FIG. 14( a )) because the display screen  121  and voice output plane  122  are formed on a uniform inside principal plane in the second housing  120 . These holding states are common in that the positional relation between a virtual plane including the voice output plane  122  and the position of the ear of the head  300  is kept substantially in parallel.  
     [0173] This is because of the following reason. That is, when a user applies the voice output plane  122  of the two folding mobile telephone to an ear of the user, the user tries to adjust the ear to the direction in which the directivity of an audio signal output from the voice output plane  122  is maximized. This operation is unconsciously performed in order to listen to an audio signal output from the voice output plane  122  as easily as possible. The virtual plane including the ear is orthogonal to the direction of the directivity of the audio signal and the virtual plane including the voice output plane  122  is also orthogonal to the direction of the directivity of the audio signal. Therefore, the positional relation between the position of the ear and the virtual plane including the voice output plane  122  is kept substantially in parallel.  
     [0174] Therefore, it is possible to adjust the positional relation between the two folding mobile telephone and the head depending on how to set the virtual plane including the voice output plane  122  in the second housing  120 . As shown in FIGS.  7 ( c ) and  8 , the plane including the display screen  121  tilts from the slope  701  with the voice output plane  122  formed by an angle φ. Therefore, in FIG. 8, the whole two folding mobile telephone opens about an end of the second housing  120  with the slope  701  formed by the angle φ in X direction compared to the case of the conventional example. Thereby, a helical antenna  114  and grounding plate  115  formed on the first housing  110  are spaced away from the head  300  of a user. The direction of the angle φ formed between the direction in which the directivity of an audio signal is maximized and the display screen  121  is set so that the angle φ becomes an obtuse angle.  
     [0175] As shown in FIG. 8, because the embodiment 2 and a conventional example 2 have housings of substantially the same dimensions, distances C and D become equal to each other. As shown by the arrow X in FIG. 8, however, because the angle of aperture from an end of the second housing of this embodiment is larger than the case of the conventional example 2 by the angle φ, distances A and B become larger than the case of the conventional example 2. In the table, the angle φ is set to 2.6°.  
     [0176] Therefore, it is possible to reduce a gain loss β due to the distance B from the grounding plate  115  up to the surface of the head  300  and a gain loss α due to the distance A from the front end of the helical antenna  114  up to the surface of the head  300  and reduce the whole gain loss.  
     [0177] In the above description, only a part of the inside principal plane of the second housing  120  including the voice output plane  122  is formed into a slope so that the slope coincides with a virtual plane orthogonal to a direction in which the directivity of an audio signal output from the voice output plane  122  is maximized. However, it is also allowed to make the virtual plane coincide with the entire inside principal plane of the second housing  120  as shown in FIGS.  9 ( a ) to ( c ).  
     [0178] Though the above embodiment is described by using a two folding mobile telephone as an example, it is also allowed to form the configuration of the slope  701  of this embodiment by combining the configuration with a straight mobile telephone which is not the two folding type like the mobile telephone  1600  shown in FIG. 16. In FIG. 16, a portion same as or corresponding to that in FIG. 1 is provided with the same symbol and its detailed description is omitted.  
     [0179] Moreover, it is allowed to form the configuration of the slope  701  of this embodiment by combining the configuration with the configuration of the embodiment 1.  
     [0180] Furthermore, it is according to the invention to combine the configurations of the embodiments 1 and 2.  
     [0181] Furthermore, though an antenna of the present invention uses a retractable helical antenna in the case of each embodiment, it is also allowed to use an antenna of another type. For example, it is possible to use the loop antenna  170  set on the first housing  110  shown in FIG. 17.  
     [0182] Furthermore, though a configuration in which the first housing  110  is provided with the antenna  114  and grounding plate  115  is shown for the embodiment 1, it is also allowed to constitute the present invention by setting the grounding plate  115  to the first housing and the antenna  114  to the second housing  120 .  
     [0183] Also in the case of the above configuration, by making the angle of aperture between the first housing  110  and second housing  120  larger than 165° of a conventional example, the whole gain is improved because the gain of the grounding plate  115  increases because the board  115  goes away from a human body through the gain decreases because the antenna  114  approaches the human body.  
     [0184] Moreover, as shown in FIG. 19, it is allowed to realize a configuration by setting the antenna  114  to the first housing  110  and the grounding plate  115  to the second housing  120 . However, it is different from the embodiment 1 in that the antenna  114  is set not to a hinge bracket  113   a  but to a position closer to the voice input plane  112 .  
     [0185] In the case of the above configuration, by making the angle of aperture between the first housing  110  and second housing  120  larger than substantially 165° of the case of a conventional example, gain is improved because the antenna  114  is spaced away from a human body and the grounding plate  115  approaches the human body. Therefore, the entire gain is improved. In this case, it is allowed to set the antenna  114  to an arbitrary position on the second housing as long as the position is spaced away from a human body when increasing the angle of aperture between the first housing  110  and second housing  120 .  
     [0186] The optimum condition between the antenna and grounding plate shown in FIG. 15 is a condition when both the antenna  114  and grounding plate  115  are set to the first housing but it does not restrict the conditions of the configurations shown in FIGS. 18 and 19.  
     [0187] Moreover, in the case of the embodiment 1, elastic holding means uses the configuration shown in FIG. 4. However, it is also allowed to use another configuration as long as the configuration makes it possible to make an angle of aperture approach a predetermined angle in accordance with an energizing force based on an elastic force.  
     [0188] As described above, according to this embodiment, it is possible to reduce gain loss due to decrease of a mobile telephone in size and thickness.