Abstract:
According to an aspect of an embodiment, a mobile terminal device includes a lower casing, an upper casing, and an intermediate casing, an intermediate casing connected to the lower casing by a hinge structure which enables the intermediate casing to rotate about an axis, the intermediate casing supporting a back surface of the upper casing by a front surface of the intermediate casing, wherein the upper casing has a first groove formed in a vertical direction with respect to the rotation axis on a surface facing the intermediate casing, the intermediate casing has a first portion protruding from a surface facing the upper casing and fitting the groove of the upper casing, and the upper casing is rotatable with respect to the intermediate casing for the portion being guided by the groove.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates a foldable mobile terminal device in which an upper casing and a lower casing are rotatably coupled. 
     2. Description of the Related Art 
     In recent years, the mobile phone is equipped with a camera function for photographing subjects, a browser function for browsing web sites, a television function for viewing television programs and so on, in addition to a standard talking function, a transmission/reception function for electronic mails, etc. The mobile phone has been used not only as means for performing communications, but also has been used, among people of all ages, as one&#39;s own multifunctional terminal that substitutes for a digital camera, personal computer, and television. 
     However, although usual televisions or personal computers have a display screen with a horizontally elongated shape, mobile phone terminals typically have a vertically elongated shape on a whole, and the display screen thereof has also a vertically elongated shape in order to improve holdability or operability by one hand. As a consequence, when a horizontally elongated shaped image displayed on a television or personal computer is browsed by the mobile telephone, the image is often displayed by reducing its size in keeping with the display screen of a vertically elongated shape, or the image is often displayed sideways with respect to the display screen and a user browses the image by holding sideways the mobile phone. This raises a problem that either of the size of an image and the holdability of the mobile phone becomes victim to the other. 
     Japanese Unexamined Patent Application Publication No. 2003-319043 discloses a foldable mobile phone including an upper casing having a display screen, a lower casing having an operator, and a support casing that is hingedly connected to the lower casing and that supports the upper casing so as to be able to rotate the upper casing in the left/right direction about a shaft. 
     However, as shown in  FIG. 2  in the above-described patent document, in order to prevent corners of the upper casing from suffering interference from the hinge when the upper casing is rotated about the shaft provided to the support casing, the lower edge of the upper casing must be significantly curved from its center toward the left and right edge of the upper casing  100 A. As a result, in the foldable mobile phone set forth in this patent document, there occurs a problem that the display screen is reduced in size or the design of the device is limited. 
     SUMMARY 
     A mobile terminal device comprises a lower casing, an upper casing, and an intermediate casing. The intermediate casing is connected to the lower casing by a hinge structure which enables the intermediate casing to rotate about an axis. The intermediate casing supports a back surface of the upper casing by a front surface of the intermediate casing. A first casing which is either the upper casing or the intermediate casing has a first groove formed in a vertical direction with respect to the rotation axis on a surface facing a second casing which is the other of the upper casing and the intermediate casing, the second casing has a first portion protruding from a surface facing the first casing and fitting the groove of the first casing, and the upper casing is rotatable with respect to the intermediate casing for the portion being guided by the groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an external appearance of a mobile phone according to an embodiment of the present invention; 
         FIG. 2  is an internal block diagram of the mobile phone according to an embodiment of the present invention; 
         FIG. 3  is a diagram showing the surface sides of a lower casing and an intermediate casing, with an upper casing removed according to an embodiment of the present invention; 
         FIG. 4  is a diagram showing the back surface side of the upper casing according to an embodiment of the present invention; 
         FIG. 5  is a perspective diagram of the upper casing, the lower casing, and the intermediate casing according to an embodiment of the present invention; 
         FIG. 6  is a diagram showing operations for inclining the upper casing toward the lower casing according to an embodiment of the present invention; 
         FIG. 7  is a diagram showing operations for inclining the upper casing toward the lower casing, in a mobile phone according to a second embodiment of the present invention; 
         FIGS. 8A and 8B , respectively, are a front view and side view of the upper casing and the intermediate casing in a mobile phone according to a third embodiment of the present invention; 
         FIG. 9  is an oblique perspective view of the upper casing and the intermediate casing according to a third embodiment of the present invention; 
         FIGS. 10A and 10B  are perspective diagrams each showing a mobile phone according to a fourth embodiment of the present invention; 
         FIGS. 11A to 11C  are enlarged diagrams each showing the vicinity of buttons in the mobile phone according to a fourth embodiment of the present invention; 
         FIGS. 12A and 12B  are diagrams each showing an operation when one of the buttons is pushed; 
         FIGS. 13A and 13B  are diagrams each showing a rotational operation of the upper casing; 
         FIGS. 14A and 14B  are diagrams each showing an operation when the one of the buttons is pushed; 
         FIGS. 15A and 15B  are diagrams each showing the upper casing in a mobile phone according to a fifth embodiment of the present invention; 
         FIG. 16  is a diagram showing the intermediate casing in the mobile phone; 
         FIG. 17  is a diagram showing operations for inclining the upper casing toward the lower casing; 
         FIG. 18  is a diagram showing the surface side of the intermediate casing in a mobile phone according to a sixth embodiment of the present invention; 
         FIG. 19  a diagram showing the back surface side of the upper casing; 
         FIG. 20  is a perspective diagram showing the upper casing, the lower casing, and the intermediate casing; 
         FIGS. 21A and 21B  are diagrams showing various dimensions in the mobile phone; 
         FIG. 22  is a diagram showing operations for inclining the upper casing toward the lower casing; 
         FIGS. 23A and 23B  are diagrams showing various dimensions in a mobile phone according to a seventh embodiment of the present invention; 
         FIG. 24  is a diagram showing operations for inclining the upper casing toward the lower casing; 
         FIGS. 25A and 25B  are diagrams showing various dimensions in a mobile phone according to an eighth embodiment of the present invention; 
         FIG. 26  is a diagram showing the surface side of the intermediate casing in a mobile phone according to a ninth embodiment of the present invention; 
         FIG. 27  is a diagram showing the back surface side of the upper casing; and 
         FIG. 28  is a diagram showing operations for inclining the upper casing toward the lower casing. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the appended drawings. 
       FIG. 1  is a diagram showing an external appearance of a mobile phone to which an embodiment of the present invention has been applied; 
     The mobile phone shown in  FIG. 1  is equipped with a photographing function for photographing subjects, a television function for viewing television programs, etc., in addition to data communications function for exchanging voices and electronic mails with an external device. 
     The mobile phone includes an upper casing  100 A with a liquid crystal panel  101 , a lower casing  100 B held in a hand by a user, and an intermediate casing  100 C hingedly connected to the lower casing  100 B. The upper casing  100 A is supported by the intermediate casing  100 C so as to be turnable in the right and left directions, and the upper casing  100 A and the intermediate casing  100 C are integrally opened/closed with respect to the lower casing  100 B. The upper casing  100 A is one example of what the present invention terms “upper casing”, and the lower casing  100 B is one example of what the present invention terms “lower casing”, and the intermediate casing  100 C is one example of what the present invention terms “intermediate casing”. The construction of each of these upper casing  10 A, lower casing  100 B, and intermediate casing  100 C is described in detail later. 
     The upper casing  100 A includes the liquid crystal panel  101  on which telephone numbers, television programs, photographed images and the like are displayed, a speaker (refer to  FIG. 2 ) provided inside, and a mouthpiece  102  for uttering voices issued from a speaker. The lower casing  100 B includes a selection button  104  used for the selection of various functions and used as a shutter button in photographing, push buttons  105  for inputting telephone numbers and so on, a microphone (refer to  FIG. 2 ) provided inside, and an ear piece  106  for transmitting the voices to the microphone. 
     Next, the internal structure of the mobile phone will be described. 
       FIG. 2  is an internal block diagram of the mobile phone. 
       FIG. 2  shows a CPU  110 , ROM  111 , nonvolatile memory  112 , RAM  113 , microphone device  121 , display device  122 , speaker device  123 , key device  124 , camera device  125 , clock  126 , short-distance device  131 , long-distance device  132 , television device  133 , media controller  140 , and rechargeable battery  150 . These are connected to one another via busses. 
     The CPU  110  has a function of executing various programs, and exerts control over the entire mobile phone. 
     The ROM  111  stores various programs to be executed by the CPU  110 , and various constants necessary for executing these various programs. The CPU  110  executes the programs stored in the ROM  111  using the RAM  113  as a work area. 
     The nonvolatile memory  112  records various pieces of information, such as an address book or received electronic mails, to be possibly rewritten. 
     The microphone device  121  is a functional block comprising a microphone for picking up voices of the user, and the processing of the voices picked up by the microphone. 
     The speaker device  123  is a functional block comprising a speaker for outputting voices to the user, and the producing of vocal signals for driving the speaker. 
     The camera device  125  is a block governing the collection of image data by photographing, the display device  122  is a block governing the display of images on the liquid crystal panel  101  (refer to  FIG. 1 ), the key device  124  is a block for detecting various key-operations by the user, and the clock  126  is a block for acquiring a current time. 
     The media controller  140  is a block for reading data from a loaded recording media  141  or writing image data and the like produced by the camera device  125  into the recording media  141 . 
     The short-distance device  131  is a block for transmitting images, telephone numbers and the like to an external device at a short distance, by infrared communications without interposition of a base station (not shown). 
     The long-distance device  132  is a block for performing talking or the exchange of electronic mails via a base station (not shown). 
     The television device  133  is a block for converting electronic waves received by an antenna into digital program data by a tuner, and causing the liquid crystal panel  101  (refer to  FIG. 1 ) to display programs expressed by the program data. 
     The mobile phone according to the present embodiment has basically the above-described constructions. 
     Next, the upper casing  100 A, lower casing  100 B, and intermediate casing  100 C will be each explained in a more detailed manner. Hereinafter, in a state where the upper casing  100 A and intermediate casing  100 C are opened with respect to the lower casing  100 B, the side on which the liquid crystal panel  101  is provided is referred to as the “surface” side, and the back of the side on which the liquid crystal panel  101  is provided is referred to as the “back” side. 
       FIG. 3  is a diagram showing the surface side of each of the lower casing  100 B and the intermediate casing  100 C, with the upper casing  100 A removed, and  FIG. 4  is a diagram showing the back surface side of the upper casing  100 A. 
     As shown in  FIG. 3 , the lower casing  100 B and the intermediate casing  100 C are connected so as to be foldable in the hinge portion  200 . The hinge portion  200  has an abutting mount  201  against which the upper casing  100 A is abutted. On the surface side of the intermediate casing  100 C, there is provided a longitudinal groove  210  extending in the vertical direction. The hinge portion  200  is one example of what the present invention terms “hinge portion”. The longitudinal groove  210  is one example of what the present invention terms “vertical groove”. The abutting mount  201  is one example of what the present invention terms “guide”, as well as one example of what the present invention terms “pillow”. In this embodiment example, the intermediate casing  100 C is one example of what the present invention terms “first casing”. 
     As shown in  FIG. 4 , on the back surface side of the upper casing  100 A, there is provided a hollow protrusion  310  having therein a through-hole  311 . The protrusion  310  is one example of what the present invention terms “protrusion”. In this embodiment example, the upper casing  100 A is one example of what the present invention terms “second casing”. 
     Fitting the protrusion  310  ( FIG. 4 ) of the upper casing  100 A into the longitudinal groove  210  ( FIG. 3 ) of the intermediate casing  100 C allows the upper casing  100 A to be turnably supported by the intermediate casing  100 C. 
       FIG. 5  is a perspective diagram of the mobile phone. 
     As shown in  FIG. 5 , the protrusion  310  of the upper casing  100 A has gotten into the longitudinal groove  210  of the intermediate casing  100 C. An electrical cable  410  for electrically connecting the upper casing  100 A and the lower casing  100 B is arranged through the through-hole  311  in the protrusion  310 . The electrical cable  410  is one example of what the present invention terms “electrical cable”. 
     The CPU  110  shown in  FIG. 2  is disposed in the lower casing  100 B, while the speaker device  123 , the camera device  125 , the display device  122  and the like are disposed in the upper casing  10 A. Therefore, the upper casing  100 A and the lower casing  100 B must be electrically connected in order to exchange instructions and various pieces of data between the CPU  110  and various components. In the mobile phone according to this embodiment, passing the electrical cable  410  through the through-hole  311  in the protrusion  310  prevents the complication of wiring. This allows the electrical cable to be short, and to be inhibited from the breaking. 
     This mobile phone also has a spring  420  for resiliently urging downward the upper casing  100 A toward the lower casing  100 B. The spring  420  is one example of what the present invention terms “resiliently-urging member”. 
       FIG. 6  is a diagram showing operations for inclining the upper casing toward the lower casing. 
     In  FIG. 6 , the electrical cable  410  and the spring  420  and the like shown in  FIG. 5  are omitted from illustration in order to make the figure easily viewable. 
     In the upright state, in which the upper casing  100 A is not inclined toward the lower casing  100 B (step S 11  in  FIG. 6 ), the spring  420  shown in  FIG. 5  resiliently urges downward the upper casing  100 A toward the lower casing  100 B, and the upper casing  100 A is maintained in a longitudinal posture with respect to the lower casing  100 B. Also, the lower side of the upper casing  100 A is abutted against the abutting mount  201  to thereby reduce wobbling of the upper casing  100 A. 
     In this embodiment, in the upright state shown in step S 11  in  FIG. 6 , it is designed that the width of the upper casing  100 A and that of the intermediate casing  100 C conform to each other and that the protrusion  310  is located at the lowest position of the longitudinal groove  210 . 
     When the upper casing  100 A is inclined toward the left side, the protrusion  310  moves upward under the guidance of the longitudinal groove  210  to thereby rotate the upper casing  100 A (step S 12  in  FIG. 6 ). At first, by the spring  420  shown in  FIG. 5 , the upper casing  100 A is resiliently urged toward the direction in which it is maintained in the upright state (step S 11  in  FIG. 6 ). However, when the upper casing  100 A is further inclined against the resiliently urging force, the upper casing  100 A is resiliently urged toward the same direction as the rotational direction from the time when the upper casing  100 A is inclined by an angle of about 45 degrees. As a result, the bottom left corner of the upper casing  100 A is guided by the abutting mount  201 , as well as the protrusion  310  moves downward under the guidance of the longitudinal groove  210 , whereby the upper casing  100 A rotates (step S 12  in  FIG. 6 ), and is felled sidelong toward the left side with respect to the lower casing  100 B (step S 13  in  FIG. 6 ). 
     In the leftward felled-sidelong state shown in step S 13 , the face  1001  of the upper casing  100 A, opposite to the lower casing  100 B is abutted against the abutting mount  201 , and further the upper casing  100 A is resiliently urged downward by the spring  420  so as to maintain its leftward felled-sidelong state, thereby reducing wobbling in the leftward felled-sidelong state. Also, in the leftward felled-sidelong state, the right edge  1002  of the upper casing  100 A is flush with the right edge of the intermediate casing  100 C, and further the upper edge  1003  of the upper casing  100 A is flush with the upper edge of the intermediate casing  100 C. 
     Next, when the user rotates the upper casing  100 A in the right direction from the leftward felled-sidelong state (step S 13  in  FIG. 6 ), the upper casing  10 A, at first, is resiliently urged by the spring  420  shown in  FIG. 5  in the direction in which the upper casing  100 A is maintained in the leftward felled-sidelong state. However, as the upper casing  100 A gets close to the upright state, it is resiliently urged in the same direction as the rotational direction. As a result, the upper casing  100 A rotates while being guided by the abutting mount  201 , and thus returns to the upright state. 
     On the other hand, when the user inclines the upper casing  100 A from the upright state (step S 11  in  FIG. 6 ) in the right direction (step S 14  in  FIG. 6 ), the protrusion  310  of the upper casing  100 A is guided by the longitudinal groove  210 , as well as the bottom right corner of the upper casing  100 A is guided by the abutting mount  201 , whereby the upper casing  100 A is felled sidelong toward the right side with respect to the lower casing  100 B (step S 15  in  FIG. 6 ). 
     As described above, according to the mobile phone of the present invention, it is possible to easily incline the upper casing  100 A leftward and rightward with respect to lower casing  100 B, without providing a large curve to each of the lower corners of the upper casing  100 A. This allows the upper casing  100 A to have a large liquid crystal panel  101 , which makes it possible to browse an image by displaying it in a large size while maintaining the holdability of the mobile phone. 
     Next, a second embodiment according to the present invention will be described. Because the second embodiment has the same construction as that of the first embodiment except that a longitudinal groove  210  in the intermediate casing  100 C in the second embodiment is different in length from that in the first embodiment. Therefore, in this embodiment, the same components as those in the first embodiment are designated by the same symbols, and description thereof is omitted. Only differences of the second embodiment from the first embodiment are described. 
       FIG. 7  is a diagram showing operations for inclining the upper casing toward the lower casing, in a mobile phone according to the present embodiment. 
     The mobile phone according to this embodiment has substantially the same construction as that according to the first embodiment shown in  FIG. 6 , but a longitudinal groove  210 ′ is longer than the longitudinal groove  210  in the first embodiment, and the protrusion  310  is designed to come to an intermediate position of the longitudinal groove  210 ′ in the upright state shown in step S 21  in  FIG. 7 . 
     When the upper casing  100 A is inclined toward the left side (step S 22  in  FIG. 7 ), as in the case of the first embodiment, the upper casing  100 A is resiliently urged downward by the spring  420  shown in  FIG. 5 , the protrusion  310  is guided by the longitudinal groove  210 ′ and the bottom left corner of the upper casing  100 A is guided by the abutting mount  201  and the like. 
     In the leftward felled-sidelong state in which the upper casing  100 A has been felled sidelong toward the left side with respect to the lower casing  100 B (step S 23  in  FIG. 7 ), the right edge  1004  of the upper casing  100 A does not become flush with the right edge  1005  of the intermediate casing  100 C, and the entire upper casing  100 A is brought close to the center, differently from the leftward felled-sidelong state in the first embodiment (step S 13  in  FIG. 6 ). 
     Also, when the upper casing  100 A is inclined (step S 24  in  FIG. 7 ) and has been completely felled sidelong toward the right side with respect to the lower casing  100 B (step S 25  in  FIG. 7 ), the left edge  1006  of the upper casing  100 A does not become flush with the left edge  1007  of the intermediate casing  100 C, and the upper casing  100 A is brought close to the center. 
     In this manner, bringing the entire upper casing  100 A close to the center when the upper casing  100 A is inclined into leftward felled-sidelong state and rightward felled-sidelong state, allows an improvement in a feeling of stability when the mobile phone is held in a hand. 
     A third embodiment according to the present invention will now be described. Because the third embodiment has the same construction as that of the first embodiment except that the shape of a hinge portion  200  in the third embodiment is different from that in the first embodiment, only differences of the third embodiment from the first embodiment are described. 
       FIGS. 8A and 8B , respectively, are a front view and a side view of the upper casing  100 A and the intermediate casing  100 C in the mobile phone according to this embodiment, and  FIG. 9  is an oblique perspective view of the upper casing  100 A and the intermediate casing  100 C in the mobile phone according to this embodiment. 
     As shown in  FIGS. 8A and 8B , in this embodiment, a dent portion  520  is provided at each of the left and right ends of the hinge portion  200  in the intermediate casing  100 C. The dent portion is one example of what the present invention call “recess portion”. 
     As shown in  FIG. 9 , the dent portion  520  is a spacing provided between the upper casing  100 A and the abutting mount  201 . As described above, when the upper casing  100 A is inclined by about 45 degrees with respect to the lower casing  100 B, the upper casing  100 A automatically rotates up to the leftward felled-sidelong state and the rightward felled-sidelong state under the resiliently urging force of the spring  420  shown in  FIG. 5 . Therefore, the user can easily fell the upper casing  100 A sideways only by holding the mobile phone in one hand, entering fingertips into the dent portions  520 , and pushing up the upper casing  100 A. 
     Next, a fourth embodiment according to the present invention will be described. In the fourth embodiment also, the same components as those in the first embodiment are designated by the same symbols, and description thereof is omitted. Only differences of the fourth embodiment from the first embodiment are described. 
       FIGS. 10A and 10B  are perspective diagrams each showing a mobile phone according to this embodiment. 
       FIG. 10A  is a perspective diagram of the mobile phone as seen from the front thereof, and  FIG. 10B  is its perspective diagram as seen from the side thereof. 
     As in the case of the mobile phone according to the first embodiment shown in  FIG. 5 , in the mobile phone according to this embodiment shown in  FIGS. 10A and 10B , the upper casing  100 A is resiliently urged downward by the spring  420 , and the upper casing  100 A is rotatably supported by the intermediate casing  100 C by the protrusion  310  of the upper casing  100 A getting into the longitudinal groove  210  provided in the intermediate casing  100 C. Also, in the mobile phone according to this embodiment, by the user pushing one of buttons  611  provided at the left and right ends, the upper casing  100 A rotates in a respective one of the left and right directions. 
       FIGS. 11A to 11C  are enlarged diagrams each showing the vicinity of the buttons  611  in the mobile phone, shown in  FIG. 10 . 
       FIG. 11A  is a side view showing the vicinity of the buttons  611  in the mobile phone,  FIG. 11B  is a perspective diagram of the vicinity of the buttons  611  as viewed from the front thereof, and  FIG. 11C  is a sectional view of the vicinity of the buttons  611  as viewed from the side thereof. Meanwhile, the mobile phone according to this embodiment has a left-side component for inclining the upper casing  100 A toward the left side and a right-side component for inclining the upper casing  100 A toward the right side. However, because the left-side component and the right-side component have the same construction, only the left-side component is hereinafter described as a representative of them. 
     The intermediate casing  100 C includes a button claw  613  that extends from the button  611 , a button spring  612  that pulls the button claw  613  toward the button  611 , a lever  614  that rotates downward about a shaft  616  by being pushed by the button claw  613 , a leaf spring  615  that resiliently urges upward the lever  614 , a lock claw  617  attached to the front end of the lever  614 , a moving claw  618  that is inhibited from its movement by the lock claw  617 , and a pulling spring  619  that pulls the moving claw  618  in the direction of the shaft  616 . The upper casing  100 A includes an erection hole  621  into which the moving claw  618  is fitted when the upper casing  100 A is in the upright state, and a falling-sidelong hole  622  into which the moving claw  618  is fitted when the upper casing  100 A is in the leftward felled-sidelong state. 
     In a state where the button  611  has not yet been pushed, the moving claw  618  is kept pulled by the pulling spring  619  in the direction of the shaft  616  (the right direction in  FIG. 11B ), but the moving claw  618  is inhibited from moving by being locked by the lock claw  617  and further by being fitted into the erection hole  621  of the upper casing  100 A. The upper casing  100 A is maintained in the upright state by being resiliently urged downward by the spring  420  shown in  FIG. 5 . 
       FIGS. 12A and 12B  are diagrams showing an operation when the button  611  is pushed, and  FIGS. 13A and 13B , and  FIGS. 14A and 14B  are diagrams showing a rotational operation of the upper casing  10 A. 
     When the user pushes the button  611 , as shown in  FIG. 12 , the lever  614  is rotated downward about the shaft  616  by the lever  614  being pushed by the button claw  613 , and the lock claw  617  gets down, whereby the lock that has inhibited the moving claw  618  is released. Upon release of the lock, the moving claw  618  is pulled by the pulling spring  619  in the right direction, in a state of being fitted in the erection hole  621  of the upper casing  100 A. As a result, as shown in  FIG. 13 , a pulling force A by the pulling spring  619  outweighs a resiliently urging force B by the spring  420  (refer to  FIG. 5 ), in the direction in which the upright state is maintained (refer to  FIG. 5 ), whereby the upper casing  100 A is rotated leftward while the protrusion  310  is guided by the longitudinal groove  210  to thereby move upward. 
     Here, since the lever  614  shown in  FIG. 12  is resiliently urged upward by the leaf spring  615 , the lever  614  is moved downward by the button  611  being pushed, thereby releasing the lock. Thus, when the moving claw  618  gets over the lock claw  617 , the lever  614  is moved upward, and the button  611  is returned to the original state. 
     When the upper casing  100 A is rotated by about  45  degrees, the moving claw  618  shown in  FIG. 12  is displaced from the erection hole  621  of the upper casing  10 A, and loses its force for pulling the upper casing  100 A in the right direction. However, as shown in  FIG. 14 , the spring  420  (refer to  FIG. 5 ) resiliently urges the upper casing  100 A in the downward direction, which is the same as the rotational direction, and rotates the upper casing  100 A up to the leftward felled-sidelong state. When the upper casing  100 A is rotated up to the leftward felled-sidelong state, the moving claw  618  is fitted into the falling-sidelong hole  622  of the upper casing  100 A, thus inhibiting the movement of the upper casing  100 A. 
     In this way, according to this embodiment, the user can easily incline the upper casing  100 A only by pushing the button  611 . 
     When attempting to return the upper casing  100 A from the leftward felled-sidelong state to the upright state, the user should slide upward the upper casing  100 A and then rotate it in the right direction. Thereupon, the moving claw  618  is displaced from the falling-sidelong hole  622  of the upper casing  100 A to thereby be moved leftward against a pulling force by the pulling spring  619 , and in the upright state, the moving claw  618  is fitted into the erection hole  621 . 
     A fifth embodiment according to the present invention will now be described. Because the fifth embodiment has the same construction as that of the first embodiment except that, in the fifth embodiment, motors and the like for automatically inclining the upper casing  100 A are provided in the upper casing  100 A and the lower casing  100 B, only differences of the fifth embodiment from the first embodiment are described. 
       FIGS. 15A and 15B  are diagrams each showing the upper casing in the mobile phone according to this embodiment, and  FIG. 16  is a diagram showing the intermediate casing in the mobile phone according to this embodiment. 
     As shown in  FIGS. 15A and 15B , the mobile phone according to this embodiment has the same protrusion  310  as that in the first embodiment shown in  FIG. 4 , and further includes, on the lower side of the upper casing  100 A, pinion gears  712 , motors  711  for rotationally driving the pinion gears  712 , and inclination buttons  700  for inclining the upper casing  100 A to respective left and right directions. 
     Also, as shown in  FIG. 16 , the mobile phone according to this embodiment includes the same longitudinal groove  210  as that in the first embodiment shown in  FIG. 3 , and a rack gear  720  with which the two pinion gears mesh. 
       FIG. 17  is a diagram showing operations for inclining the upper casing  100 A toward the lower casing  100 B, in the mobile phone according to this embodiment. 
     In this embodiment, in the upright state of the upper casing  100 A (step S 31  in  FIG. 17 ), the protrusion  310  is disposed at the lowest position of the longitudinal groove  210 , and the two pinion gears  712  provided in the upper casing  100 A is in a meshing engagement with the rack gear  720  provided in the intermediate casing  100 C. 
     When the user pushes the inclination button  700  for inclining the upper casing  100 A toward the left side, a drive instruction is issued from the CPU  110  to the motor  711 , and the motor  711  is rotationally driven in the right direction. As a result, the two pinion gears  712  are rotated and moved along the rack gear  720  in the right direction, and after the right pinion gear  712  has been displaced from the rack gear  720 , the protrusion  310  is guided by the longitudinal groove  210 , as well as the left pinion gear  712  is guided by the longitudinal groove  210 , thereby rotating the upper casing  100 A in the left direction (step S 32  in  FIG. 17 ). 
     When the upper casing  100 A is inclined in the left direction, the upper casing  100 A is abutted against the abutting mount  201 , and the movement of the pinion gear  712  is stopped (step S 33  in  FIG. 17 ). 
     When the user pushes the inclination button  700  for inclining the upper casing  100 A toward the right side, the motor  711  is rotationally driven in the left direction. As a result, the two pinion gears  712  are moved in the left direction, and after the left pinion gear  712  has been displaced from the rack gear  720 , the upper casing  100 A is rotated in the right direction (step S 34  in  FIG. 17 ). When the upper casing  100 A is inclined up to the rightward felled-sidelong state, the movement of the pinion gear  712  is stopped (step S 35  in  FIG. 17 ). 
     As described above, according to the mobile phone of this embodiment, the user can easily incline the upper casing  100 A only by pushing the button  611 , without applying a large force. 
     Next, a sixth embodiment according to the present invention will be described. In the sixth embodiment also, the same components as those in the first embodiment are designated by the same symbols, and description thereof is omitted. Only differences of the sixth embodiment from the first embodiment are described. 
       FIG. 18  is a diagram showing the surface side of the intermediate casing  100 C in the mobile phone according to this embodiment. 
     As shown in  FIG. 18 , the intermediate casing  100 C according to this embodiment has a longitudinal groove  210  that vertically extends, as in the intermediate casing  100 C in the first embodiment, and further, has a V-groove  211  that extends in the left and right directions, formed below the longitudinal groove  210 . The V-groove is one example of what the present invention terms “guide groove”. 
       FIG. 19  is a diagram showing the back surface side of the upper casing  100 A in the mobile phone according to this embodiment. 
     As shown in  FIG. 19 , as in the case of the upper casing  100 A in the first embodiment shown in  FIG. 4 , the upper casing  100 A has an protrusion  310  to be fitted into the longitudinal groove  210 , and further, has an auxiliary protrusion  312  to be fitted into the V-groove  211 . The auxiliary protrusion  312  is one example of what the present invention terms “guide pin”. 
       FIG. 20  is a perspective diagram showing the upper casing  100 A, the lower casing  100 B, and the intermediate casing  100 C. 
     The mobile phone according to the present invention also has a spring  420  that is connected to the protrusion  310  and that resiliently urges the upper casing  100 A in the downward direction. Also, in this embodiment, the auxiliary protrusion  312  has a through-hole, and an electrical cable  410  for electrically connecting the upper casing  100 A and the lower casing  100 B is arranged through the through-hole of the auxiliary protrusion  312 . Passing the electrical cable  410  through the through-hole of the auxiliary protrusion  312  allows the prevention of breaking of the electrical cable  410 , as well. 
       FIGS. 21A and 21B  are diagrams showing various dimensions in the mobile phone according to this embodiment. 
     In the mobile phone according to this embodiment, in the leftward felled-sidelong state shown in  FIG. 21A , the distance B 1  between the right edge of the upper casing  100 A and the center of the protrusion  310  is made equal to the distance B 2  between the lower edge of the upper casing  100 A and the center of the auxiliary protrusion  312 , and the distance C 1  between the center of the protrusion  310  and the center of the auxiliary protrusion  312  is made equal to the distance C 2  between the center of the protrusion  310  and the center of the auxiliary protrusion  312  in the upright state shown in  FIG. 20B . Also, in order to smoothly rotate the upper casing  100 A, a spacing A is provided between the lower edge of the upper casing  100 A and the abutting mount  201 . By using the upper casing  100 A and intermediate casing  100 C with such dimensions, it is possible to bring the right edge of the upper casing  100 A in line with that of the intermediate casing  100 C, in the leftward felled-sidelong state, and to bring the left edge of the upper casing  100 A in line with that of the intermediate casing  100 C, in the rightward felled-sidelong state. Furthermore, in both of the leftward felled-sidelong state and rightward felled-sidelong state, it is possible to bring the upper edge of the upper casing  100 A in line with that of the intermediate casing  100 C. 
       FIG. 22  is a diagram showing operations for inclining the upper casing  100 A toward the lower casing  100 B. 
     As shown in  FIG. 21B  also, when the upper casing  100 A is in the upright state (step  41  in  FIG. 22 ), the protrusion  310  is located at the lowest position of the longitudinal groove  210 , and an auxiliary protrusion  313  is located at the lowest position of the V-groove  212 . 
     When the user inclines the upper casing  100 A toward the left side, first, the protrusion  310  moves upward under the guidance of the longitudinal groove  210 , as well as the auxiliary protrusion  312  moves upward along the right side groove of the V-groove  211 , and the upper casing  100 A starts rotating in the left direction against the resiliently urging force of the spring  420  (step S 42  in  FIG. 22 ). 
     Upon being rotated by about 45 degrees, the upper casing  100 A is resiliently urged by the spring  420  in the same direction as the rotational direction, and the upper casing  100 A is rotated while the bottom corner thereof is guided by the abutting mount  201 , to thereby be felled sidelong leftward with respect to the lower casing  100 B (step  43  in  FIG. 22 ). 
     On the other hand, when the user inclines the upper casing  100 A toward the right side (step  44  in  FIG. 22 ), the protrusion  310  is guided by the longitudinal groove  210  and the auxiliary protrusion  312  is guided by the left side groove of the V-groove  211  and moves along it, whereby the upper casing  100 A is rotated in the right direction, and is felled sidelong rightward with respect to the lower casing  100 B (step S 45  in  FIG. 22 ). Thus providing the V-groove  211  in addition to the longitudinal groove  210  allows the upper casing  100 A to be more smoothly inclined. 
     Next, a seventh embodiment according to the present invention will be described. Because the seventh embodiment has the same construction as that of the sixth embodiment except that the dimension of a longitudinal groove  210  in this embodiment is different from that of the sixth embodiment, only differences of the seventh embodiment from the sixth embodiment are described. 
       FIGS. 23A and 23B  are diagrams showing various dimensions in the mobile phone according to this embodiment of the present invention. 
     In the mobile phone according to this embodiment, in the leftward felled-sidelong state shown in  FIG. 23A , when the distance between the right edge of the intermediate casing  100 C and that of the upper casing  100 A is represented as β, and the distance between the center of the protrusion  310  and that of the auxiliary protrusion  312  is represented as J, let the distance between the right edge of the upper casing  100 A and the center of the protrusion  310  be (H+β), and let the distance between the center of the protrusion  310  and that of the auxiliary protrusion  312  in the upright state shown in  FIG. 23B  be (J−β). Moreover, in order to smoothly rotate the upper casing  10 A, a spacing D is provided between the lower edge of the upper casing  100 A and the abutting mount  201 . Forming the upper casing and the intermediate casing with such dimensions makes it possible, in the leftward felled-sidelong state and the rightward felled-sidelong state, to bring the upper casing  100 A close to the center and to improve the stability when the user holds the mobile phone in a hand. 
       FIG. 24  is a diagram showing operations for inclining the upper casing  100 A toward the lower casing  100 B. 
     As shown in  FIG. 23B  also, when the upper casing  100 A is in the upright state (step  51  in  FIG. 24 ), the protrusion  310  is located at the central position of the longitudinal groove  210 , and the auxiliary protrusion  312  is located at the lowest position of the V-groove  211 . 
     When the user inclines the upper casing  100 A toward the left side, the protrusion  310  is guided by the longitudinal groove  210 , and the auxiliary protrusion  312  is guided by the right side groove of the V-groove  211  and moves along it, whereby the upper casing  100 A rotates in the left direction (step S 52  in  FIG. 24 ). 
     When the upper casing  100 A is rotated up to the leftward felled-sidelong state (step  53  in  FIG. 24 ), the upper casing  100 A is subjected to an interference with the abutting mount  201 , and the movement of the upper casing  100 A is stopped. 
     On the other hand, when the user inclines the upper casing  100 A toward the right side (step  54  in  FIG. 24 ), the protrusion  310  is guided by the longitudinal groove  210  and the auxiliary protrusion  312  is guided by the left side groove of the V-groove  211  and moves along it, whereby the upper casing  100 A is rotated in the right direction and felled sidelong rightward with respect to the lower casing  100 B (step S 55  in  FIG. 24 ). 
     In this manner, according to the mobile phone according to this embodiment, the upper casing  100 A can be brought close to the center when the upper casing  100 A is inclined. 
     An eighth embodiment according to the present invention will now be described. Because the eighth embodiment has the same construction as that of the seventh embodiment except that, in this embodiment, the dimension of a spacing between the intermediate casing and the intermediate casing is different from that of the seventh embodiment, only differences of the eighth embodiment from the seventh embodiment are described. 
       FIGS. 25A and 25B  are diagrams showing various dimensions in the mobile phone according to this embodiment. 
     In the mobile phone according to this embodiment, when the distance between the right edge of the intermediate casing  100 C and that of the upper casing  100 A in the leftward felled-sidelong state shown in  FIG. 25A  is represented as α, and the distance between the center of the protrusion  310  and that of the auxiliary protrusion  312  is represented as F, and when the distance between the lower edge of the upper casing  100 A in the upright state shown in  FIG. 25B  and the abutting mount  201  is represented D, let the distance between the right edge of the upper casing  100 A and the center of the protrusion  310  in the leftward felled-sidelong state shown in  FIG. 25A  be (E+α), and let the distance between the center of the protrusion  310  and the center of the auxiliary protrusion  312  in the upright state of the upper casing  100 A shown in  FIG. 25B  be F. According to the mobile phone of this embodiment, when the upper casing  100 A is inclined up to the leftward felled-sidelong state or the rightward felled-sidelong state, it is possible to bring the upper casing  100 A close to the center and to raise up the upper casing  100 A. 
     Next, a ninth embodiment according to the present invention will be described. In the ninth embodiment of the present invention also, the same components as those in the first embodiment are designated by the same symbols, and description thereof is omitted. Only differences of the ninth embodiment from the first embodiment are described. 
       FIG. 26  is a diagram showing the surface side of the intermediate casing  100 C in the mobile phone according to this embodiment. 
     As shown in  FIG. 26 , as in the case of the intermediate casing  100 C in the first embodiment shown in  FIG. 3 , the intermediate casing  100 C in this embodiment has a longitudinal groove  210  that vertically extends, and further has an auxiliary protrusion  313  that protrudes toward the lower casing  100 B. This auxiliary protrusion  313  is also one example of what the present invention terms “guide pin”. 
       FIG. 27  is a diagram showing the back surface side of the upper casing  100 A in the mobile phone according to this embodiment. 
     As in the case of the upper casing  100 A in the first embodiment shown in  FIG. 4 , the upper casing  100 A in this embodiment has a protrusion  310  to be fitted into the longitudinal groove  210 , and further has an arcuate groove  212  into which the auxiliary protrusion  313  is to be fitted. The arcuate groove  212  has a shape such that bilaterally symmetrical two arc-shaped grooves are connected at the center of the arcuate groove. This arcuate groove  212  is also one example of what the present invention terms “guide groove”. 
       FIG. 28  is a diagram showing operations for inclining the upper casing  100 A toward the lower casing  100 B. 
     When the upper casing  100 A is in the upright state (step  61  in  FIG. 28 ), the protrusion  310  is located at the lowest position of the longitudinal groove  210 , and an auxiliary protrusion  313  is fitted in the central position of the arcuate groove  212 . 
     When the user inclines the upper casing  100 A toward the left side, first, the protrusion  310  is guided by the longitudinal groove  210  to thereby vertically moves, and the left side groove of the arcuate groove  212  slides with the auxiliary protrusion  313  fitted-in, whereby the upper casing  100 A rotates in the left direction (step S 62  in  FIG. 28 ). 
     In the leftward felled-sidelong state in which the upper casing  100 A is felled sidelong leftward with respect to the lower casing  100 B (step  63  in  FIG. 28 ), the protrusion  310  has been moved to the lowest position of the longitudinal groove  210 , and the auxiliary protrusion  313  is fitted in the front end of the left side groove of the arcuate groove  212 . 
     On the other hand, when the user inclines the upper casing  100 A toward the right side (step  64  in  FIG. 28 ), the protrusion  310  is guided by the longitudinal groove  210 , and the right side groove of the arcuate groove  212  slides with the auxiliary protrusion  313  fitted-in, whereby the upper casing  100 A rotates in the right direction (step S 65  in  FIG. 28 ). As described above, using the arcuate groove instead of the V-groove allows the upper casing  100 A to be smoothly inclined, as well. Furthermore, sliding the groove with the auxiliary protrusion fitted-in instead of moving the auxiliary protrusion along the groove allows the upper casing  100 A to be rotated, as well. 
     Hereinbefore, examples in which the mobile terminal device according to the present invention is applied to mobile phones have been described, but the mobile terminal device according to the present invention may be applied to a personal digital assistant (PDA) and so on. 
     Also, in the forgoing description, examples in which the longitudinal groove is provided in the intermediate casing, and the protrusion is provided in the upper casing have been explained. However, the vertical groove termed by the present invention may be provided in the upper casing instead of the intermediate casing, and the protrusion termed by the present invention may be provided in the intermediate casing instead of the upper casing. 
     Besides, the hinge portion termed by the present invention may be configured integrally with the intermediate casing or the lower casing, or alternatively, may be configured as a hinge module, individually of the casings.