Patent Publication Number: US-2023160417-A1

Title: Raising/lowering-type biaxial hinge and terminal apparatus using said raising/lowering-type biaxial hinge

Description:
FIELD OF THE INVENTION 
     The invention relates to a raising/lowering-type biaxial hinge especially suitably used in a dual-screen foldable tablet with a keyboard, which is a kind of terminal device, and to the dual-screen foldable tablet with the keyboard, which further uses the raising/lowering-type biaxial hinge. 
     BACKGROUND ART 
     Among biaxial hinges used in a terminal device, such as a foldable notebook PC, an electronic dictionary or a PDA, the ones disclosed in Patent Documents 1 and 2 below are known. 
     BACKGROUND ART DOCUMENTS 
     Patent Documents 
     
         
         [Patent Document1] JP Laid-Open Patent Application No. 2018-10422 
         [Patent Document2] JP Laid-Open Patent Application No. 2019-35474 
       
    
     SUMMARY OF INVENTION 
     Problem to be Solved by the Invention 
     Each of conventional biaxial hinges as described above enables a first casing making up a keyboard portion and a second casing making up a display portion to be opened and closed 360 degrees assuring a free stop, but cannot adjust a shaft-to-shaft distance between a first hinge shaft and a second hinge shaft making up the biaxial hinge. 
     Recently, a dual-screen foldable tablet with a keyboard has been developed. This kind of terminal device is developed to ensure that a separate keyboard is prepared to enhance its user-friendliness, that this keyboard is placed on the first casing to allow for its use as in an ordinary PC with a keyboard, and that a keyboard panel is placed between a first casing and a second casing during its transport to allow for its movement. 
     In such a terminal device, its thickness varies with or without a keyboard panel, so that a biaxial hinge for enabling an adjustment of shaft-to-shaft distance between a first hinge shaft and a second hinge shaft of the biaxial hinge to make only one type of biaxial hinge compatible with both uses of the terminal device. 
     Therefore, an object of the invention is to provide a raising/lowering-type biaxial hinge configured to avoid troubles in its opening and closing operation even if a keyboard panel is placed on a first upper surface making up a terminal device, as well as a terminal device using this raising/lowering-type biaxial hinge. 
     Solution to Problem 
     To meet an object as mentioned above, a raising/lowering-type biaxial hinge according to claim  1  is characterized in that it is composed of a movable hinge shaft attached to a first casing side; a fixed hinge shaft attached to a second casing side; a first coupling member for movably coupling the movable hinge shaft and for rotatably bearing the fixed hinge shaft at a fixed position; a plurality of second coupling members for rotatably bearing the movable hinge shaft at a shift position and for movably coupling a first displaceable rotary shaft and a second displaceable rotary shaft provided between the movable hinge shaft and the fixed hinge shaft; a plurality of third coupling members for coupling the fixed hinge shaft and the first displaceable rotary shaft, the first displaceable rotary shaft and the second displaceable rotary shaft, and the second displaceable rotary shaft and the movable hinge shaft to avoid change in their respective shaft-to-shaft distances; and a synchronous rotation mechanism provided between the movable hinge shaft and the fixed hinge shaft on one hand, and between the first displaceable rotary shaft, and the second displaceable rotary shaft on the other. 
     Here, a raising/lowering-type biaxial hinge according to claim  2  is characterized in that a guide long hole into which a movable hinge shaft is slidably inserted and a first bearing hole in which a fixed hinge shaft is rotatably borne are provided on a first coupling member. 
     Further, a raising/lowering-type biaxial hinge according to claim  3  is characterized in that bent guide long holes into which a movable hinge shaft is slidably inserted and a second bearing hole in which a fixed hinge shaft is borne are provided on each of second coupling members. 
     Further, a raising/lowering-type biaxial hinge according to claim  4  is characterized in that a shaft-to-shaft distance stabilizing mechanism is provided, wherein it is made up of a pair of hook members attached to a movable hinge shaft and engaged with a fixed hinge shaft. 
     Further, a raising/lowering-type biaxial hinge according to claim  5  is characterized in that a synchronous rotation mechanism is made up of gears provided on a movable hinge shaft and a fixed hinge shaft, and meshed with each other. 
     Here, a raising/lowering-type biaxial hinge according to claim  6  is characterized in that friction torque generation mechanisms are provided on a movable hinge shaft and a fixed hinge shaft and a first displaceable rotary shaft, and a second displaceable rotary shaft. 
     Further, a raising/lowering-type biaxial hinge according to claim  7  is characterized in that each of friction torque generation mechanisms comprises friction washers and disc springs, wherein a movable hinge shaft and a fixed hinge shaft, and a first displaceable rotary shaft and a second displaceable rotary shaft are respectively inserted into both of these. 
     Next, the invention according to claim  8  is characterized in that a terminal device uses a raising/lowering-type biaxial hinge as described above. 
     Advantageous Effects of Invention 
     Following the invention according to claim  1 , when a raising/lowering-type biaxial hinge according to the invention is used in a dual-screen foldable tablet being an example of a terminal device: when a first casing is opened relative to a second casing, a fixed hinge shaft is rotated to enable an opening and closing operation of the second casing via a second bracket; at the same time, a rotation of a fixed hinge shaft is transmitted from a first displaceable rotary shaft to a second displaceable rotary shaft and to a movable hinge shaft via a synchronous rotation mechanism, the first casing is opened in its opening direction opposite to an opening direction of the second casing, so that the first casing and the second casing are opened, with their opening and closing angle changing from 0 degree to 90 degrees, then from 90 degrees to 180 degrees, further from 180 degrees to 360 degrees. 
     Following the invention according to claim  2 , a movable hinge shaft slides and moves inside a guide long hole relative to a fixed hinge shaft rotatably borne at a fixed position in a first bearing hole of a first coupling member to change a shaft-to-shaft distance between a fixed hinge shaft and a movable hinge shaft. 
     Further, a raising/lowering-type biaxial hinge according to claim  3  is characterized in that bent guide long holes into which a movable hinge shaft is slidably inserted and a second bearing hole in which a fixed hinge shaft is borne are provided on each of second coupling members. 
     Following the invention according to claim  4 , hook members making up a shaft-to-shaft distance stabilizing mechanism can more securely prevent change in a shaft-to-shaft distance between a fixed hinge shaft and a movable hinge shaft. 
     Following the invention according to claim  5 , a rotation drive force can be more securely transmitted from a fixed hinge shaft to a first displaceable rotary shaft and from a second displaceable rotary shaft to a movable hinge shaft, or inversely, than a synchronous rotation mechanism using gears. 
     Following the invention according to one of claims  6  and  7 , a friction torque is generated at the time of respective rotations of a movable hinge shaft, a fixed hinge shaft, a first displaceable rotary shaft and a second displaceable rotary shaft, a first casing and a second casing can be stopped assuring a free stop during their opening and closing operation, and a display portion installed on a second casing side can be held to avoid a change in opening and closing angle, even if it is touched by a finger or a stylus. 
     Following the invention according to claim  8 , a terminal device comprising a raising/lowering-type biaxial hinge having features as described above can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  to  FIG.  1 C  show a dual-screen foldable tablet being an example of a terminal device using a raising/lowering-type biaxial hinge according to the invention,  FIG.  1 A  being a perspective view of its closed state,  FIG.  1 B  its side view, and  FIG.  1 C  a side view of its opened state at 90 degrees; 
         FIG.  2    shows a perspective view of a raising/lowering-type biaxial hinge according to the invention; 
         FIG.  3    shows a plan view with a partial cross section of a raising/lowering-type biaxial hinge as shown in  FIG.  2   ; 
         FIG.  4    shows an exploded perspective view of a raising/lowering-type biaxial hinge as shown in  FIG.  2   ; 
         FIG.  5 A  and  FIG.  5 B  show a movable hinge shaft and a fixed hinge shaft of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  5 A  being its elevation view, and  FIG.  5 B  its plan view; 
         FIG.  6    shows a perspective view of a first coupling member of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ; 
         FIG.  7 A  and  FIG.  7 B  show a first displaceable rotary shaft of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  7 A  being its elevation view, and  FIG.  7 B  its plan view; 
         FIG.  8 A  and  FIG.  8 B  show a second displaceable rotary shaft of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  8 A  being its elevation view, and  FIG.  8 B  its plan view; 
         FIG.  9 A  and  FIG.  9 B  show second coupling members of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  9 A  being a perspective view of a second A coupling member and a second B coupling member, and  FIG.  9 B  a perspective view of a second C coupling member; 
         FIG.  10    shows a perspective view of a third coupling member of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ; 
         FIG.  11 A  and  FIG.  11 B  show a shaft-to-shaft distance stabilizing mechanism of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  11 A  being a perspective view of a hook member, and  FIG.  11 B  its plan view with a partial cross section; 
         FIG.  12 A  to  FIG.  12 D  are illustrative views showing an operation of a raising/lowering-type biaxial hinge as shown in  FIG.  3    and  FIG.  4   ,  FIG.  12 A  showing a closed state in which a first casing and a second casing are at 0 degree,  FIG.  12 B  a state in which they are opened 80 degrees,  FIG.  12 C  a state in which they are opened 180 degrees and  FIG.  12 D  a state in which they are opened 360 degrees; 
         FIG.  13 A  to  FIG.  13 C  show another terminal device using a raising/lowering-type biaxial hinge according to the invention,  FIG.  13 A  being a perspective view of its closed state,  FIG.  13 B  its side view, and  FIG.  13 C  a side view of its opened state at 90 degrees; and 
         FIG.  14 A  to  FIG.  14 C  are illustrative views showing an operation of a raising/lowering-type biaxial hinge according to the invention in case of a terminal device as shown in  FIGS.  13 A to  13 C ,  FIG.  14 A  showing a closed state in which a first casing and a second casing are at 0 degree,  FIG.  14 B  a state in which they are opened 80 degrees, and  FIG.  14 C  a state in which they are opened 180 degrees. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following, reference is made to a raising/lowering-type biaxial hinge according to the invention as applied to a terminal device being a dual-screen foldable tablet comprising a first casing and a second casing; but examples of a terminal device to which the invention is applied include terminal devices such as notebook type PC, laptop type PC and PDAs in particular an electronic dictionary. Furthermore, it can be also used in various devices or containers in which a first casing and a second casing are openably and closably coupled by a raising/lowering-type biaxial hinge. 
     Embodiment 1 
     A terminal device  1  to which the invention is applied, especially that in Embodiment 1 is a dual-screen foldable tablet comprising a first casing  2  provided with a first display portion  2   a  and a second casing  3  provided with a second display portion  3   a  as shown in  FIGS.  1 A to  1 C ; additionally it comprises a separate keyboard panel  21 , and the terminal device  1  can be carried together with the keyboard panel  21  as placed between the first casing  2  and the second casing  3 , as shown in  FIG.  13 A  to  FIG.  13 C . 
     A pair of raising/lowering-type biaxial hinges  4 ,  4  are configured to ensure that no problem occurs, even if a first casing  2  and a second casing  3  are closed as a keyboard panel  21  is placed between the first casing  2  and the second casing  3 ; raising/lowering-type biaxial hinges  4 ,  4  are attached at a predetermined interval on the right and left on respective rear end portions of the first casing  2  and the second casing  3 . The first casing  2  and the second casing  3  are coupled by the raising/lowering-type biaxial hinges  4 ,  4  to be openable and closable relative to each other. In other words, a terminal device  1  is configured to ensure that the first casing  2  and the second casing  3  can be opened from a closed state of 0 degree to a fully-opened state, having an angle of e.g. 90 degrees, 180 degrees, 270 degrees and 360 degrees and also restore the closed state of 0 degree from 360 degrees, having an angle of e.g. 270 degrees, 180 degrees, 90 degrees and then 0 degree, and that the first casing  2  and the second casing  3  can be opened and closed from 0 degree to 360 degrees, even if the first casing  2  and the second casing  3  are closed, as the keyboard panel  21  is placed between the first casing  2  and the second casing  3 . 
     A first display portion  2   a  and a second display portion  3   a  have a function of enabling touch input operations by a finger, etc. on a screen, in addition to that of displaying a calculated image. In this embodiment, as a pair of raising/lowering-type biaxial hinges  4 ,  4  having the same structure are provided on the right and left, reference is made in the following to a raising/lowering-type biaxial hinge  4  on the right in  FIG.  1 A , and a raising/lowering-type biaxial hinge  4  on the left is not described. 
     A raising/lowering-type biaxial hinge  4  as described above is housed inside a case portion A, especially as shown in  FIG.  2    to  FIG.  4   , while respective portions of a movable hinge shaft  6  and a fixed hinge shaft  7 , as well as a first bracket  5  and a second bracket  8  project outside. 
       FIG.  3   ,  FIGS.  11 A and  11 B  show a concrete structure of a raising/lowering-type biaxial hinge  4  as described above, and as shown in respective drawings, the raising/lowering-type biaxial hinge  4  comprises a movable hinge shaft  6  attached via a first bracket  5  to a first casing  2  on which a first display portion  2   a  is installed; a fixed hinge shaft  7  attached via a second bracket  8  to a second casing  3  on which a second display portion  3   a  is installed; a guide long hole  9   a  for movably bearing the movable hinge shaft  6 ; a first coupling member  9  comprising a first bearing hole  9   b  for rotatably pivotally supporting the fixed hinge shaft  7  at a fixed position; three second coupling members, i.e. a second A coupling member  10 , a second B coupling member  11  and a second C coupling member  12 , respectively comprising bent guide long holes  10   a ,  11   a ,  12   a  for movably and rotatably bearing the movable hinge shaft  6  and second bearing holes  10   b ,  11   b ,  12   b  for rotatably bearing the fixed hinge shaft  7  at a fixed position; seven third coupling members  15 ,  15 ,  15  . . . for coupling the movable hinge shaft  6  and the fixed hinge shaft  7 , as well as a first displaceable rotary shaft  13  and the second displaceable rotary shaft  14  to avoid changes in their respective shaft-to-shaft distances; a shaft-to-shaft distance stabilizing mechanism B provided between the movable hinge shaft  6  and the first displaceable rotary shaft  13 ; and a synchronous rotation mechanism C provided between the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14 . 
     Still further, a first friction torque generation mechanism F 1 , a second friction torque generation mechanism F 2 , a third friction torque generation mechanism F 3  and a fourth friction torque generation mechanism F 4  can be respectively provided on a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 . It is noted that in this specification and claims, the first friction torque generation mechanism F 1 , the second friction torque generation mechanism F 2 , the third friction torque generation mechanism F 3  and the fourth friction torque generation mechanism F 4  are collectively referred to as friction torque generation mechanisms F. Still further, the number of respective friction torque generation mechanisms F is not limited to that in Embodiments. These can be provided on some of a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 . 
     In the following, reference is made to respective members in order. It is noted that in what follows, a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14  are collectively referred to as respective shafts. 
     First, especially as shown in  FIGS.  5 A and  5 B , a movable hinge shaft  6  comprises, as seen from its one end portion, an attaching flat portion  6   b  comprising flange portions  6   a ,  6   a  on its both end portions and formed by slicing off a section between these flange portions  6   a ,  6   a ; a first small diameter portion  6   c  provided next to the attaching flat portion  6   b  and having a circular cross section; a first gear portion  6   d  provided next to the first small diameter portion  6   c  and having a diameter larger than the first small diameter portion  6   c ; a second small diameter portion  6   e  provided next to the first gear portion  6   d ; a third small diameter portion  6   f  provided next to the second small diameter portion  6   e ; a fourth small diameter portion  6   g  provided next to the third small diameter portion  6   f ; a deformed shaft portion  6   h  provided from the middle of the fourth small diameter portion  6   g ; and a male screw portion  6   i  provided on one end portion of the deformed shaft portion  6   h.    
     It is noted that a plurality of attaching holes  6   k ,  6   k  . . . are provided on an attaching flat portion  6   b  of a movable hinge shaft  6 , and a first bracket  5  is fixedly attached by attaching screws  6   m ,  6   m  . . . passing through these attaching holes  6   k ,  6   k  . . . ; as it is structured in a well-known manner, it is not concretely shown in the drawings, but a rear end portion of a first casing  2  is attached to the first bracket  5 . As per attaching holes provided on the first bracket  5 , reference numerals  5   a ,  5   a  denote the ones for attaching via the attaching screws  6   m ,  6   m  . . . to the movable hinge shaft  6 , while reference numerals  5   b ,  5   b  denote the ones for attaching using the attaching screws (not shown) to the first casing  2 . It is noted that reference numerals  5   c ,  5   c  denote spacers. 
     Next, a fixed hinge shaft  7  is of the same structure as a movable hinge shaft  6 ; as is equally shown by reference numerals in parentheses in  FIGS.  5 A and  5 B , it comprises an attaching flat portion  7   b  comprising flange portions  7   a ,  7   a  on its both end portions and formed by slicing off a section between these flange portions  7   a ,  7   a ; a first small diameter portion  7   c  provided next to the attaching flat portion  7   b  and having a circular cross section; a first gear portion  7   d  provided next to the first small diameter portion  7   c  and having a diameter larger than the first small diameter portion  7   c ; a second small diameter portion  7   e  provided next to the first gear portion  7   d ; a third small diameter portion  7   f  provided next to the second small diameter portion  7   e ; a fourth small diameter portion  7   g  provided next to the third small diameter portion  7   f ; a deformed shaft portion  7   h  provided from the middle of the fourth small diameter portion  7   g ; and a male screw portion  7   i  provided on one end portion of the deformed shaft portion  7   h.    
     It is noted that a second bracket  8  is fixedly attached to an attaching flat portion  7   b  of a fixed hinge shaft  7  by attaching screws  7   m ,  7   m  . . . passing through a plurality of attaching holes  8   a ,  8   a  . . . provided on it; as it is structured in a well-known manner, it is not concretely shown in the drawings, but a rear end portion of a second casing  3  is attached to the second bracket  8 . Reference numerals  8   b ,  8   b  . . . on the second bracket  8  denote attaching holes for attaching using attaching screws (not shown) to the second bracket  8 . 
     Next, a first coupling member  9  is a single plate-like article having a substantially oval form in plan view, as shown in  FIG.  4    and  FIG.  6   , wherein a guide long hole  9   a  for movably bearing flange portions  6   a  of a movable hinge shaft  6  is provided on its one end portion, and a first bearing hole  9   b  for rotatably bearing flange portions  7   a  of a fixed hinge shaft  7 ; the first coupling member  9  has an insertion convex portion  9   c  on its one end surface, and as shown in  FIG.  4   , it also functions as a lid body for a case portion A at the same time by fitting the insertion convex portion  9   c  into an inlet of the case portion A. 
     Especially as shown in  FIG.  4   ,  FIGS.  7 A and  7 B , a first displaceable rotary shaft  13  comprises a first small diameter portion  13   a  provided with a circumferential groove  13   b  on its end portion; a third gear portion  13   c  provided next to the first small diameter portion  13   a ; a second small diameter portion  13   d  provided next to the first gear portion  13   c ; a flange portion  13   e  of a slightly larger diameter provided next to the second small diameter portion  13   d ; a long third small diameter portion  13   f  provided next to the flange portion  13   e ; a deformed shaft portion  13   g  provided on the third small diameter portion  13   f ; and a male screw portion  13   h  provided on the deformed shaft portion  13   g.    
     Especially as shown in  FIG.  4   ,  FIGS.  8 A and  8 B , a second displaceable rotary shaft  14  comprises a fourth gear portion  14   a  provided on its end portion; a first small diameter portion  14   b  provided next to the fourth gear portion  14   a ; a flange portion  14   c  of a slightly larger diameter provided next to the first small diameter portion  14   b ; a long second small diameter portion  14   d  provided next to the flange portion  14   c ; a deformed shaft portion  14   e  provided next to the second small diameter portion  14   d ; and a male screw portion  14   f  provided on the deformed shaft portion  14   e.    
     Next, especially as shown in  FIG.  3   ,  FIG.  4   ,  FIGS.  9 A and  9 B , second coupling members are composed of three second coupling members, i.e. a second A coupling member  10 , a second B coupling member  11  and a second C coupling member  12  arranged at predetermined intervals on an inner side from a first coupling member  9 , i.e. on the side located inside a case portion A; as shown in  FIG.  9 A , the second A coupling member  10  and the second B coupling member  11  have the same structure, while a female screw hole  12   c  to which an attaching rod  20  is attached is provided on the second C coupling member  12  as shown in  FIG.  4    and  FIG.  9 B . The attaching rod  20  fixes a raising/lowering-type biaxial hinge  4  to the case portion A; its one end portion side is fixed by screw to the second C coupling member  12 , while its free end side is fixed by an attaching screw a to a side plate portion of the case portion A. Moreover, three second coupling members in total, i.e. the second A coupling member  10 , the second B coupling member  11  and the second C coupling member  12  are provided in this Embodiment, but their number is not limited. 
     Especially as shown in  FIG.  9 A , a second A coupling member  10  and a second B coupling member  11  are plate-like articles having a size and shape having their outer circumferences in contact with the inner surface of a case portion A over its overall circumference; these respectively comprise bent guide long holes  10   a ,  11   a  for movably bearing a second small diameter portion  6   e  of a movable hinge shaft  6 , as well as a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 ; and second bearing holes  10   b ,  11   b  respectively provided facing these bent guide long holes  10   a ,  11   a  for bearing and rotatably pivotally supporting a fixed hinge shaft  7  at a fixed position. 
     Especially as shown in  FIG.  9 B , a second C coupling member  12  is a plate-like element having a size and shape having its outer circumference in contact with the inner surface of a case portion A over its overall circumference; it comprises a bent guide long hole  12   a  for movably bearing a second small diameter portion  6   e  of a movable hinge shaft  6 , as well as a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 ; a second bearing hole  12   b  provided facing this bent guide long hole  12   a  for bearing and rotatably pivotally supporting a fixed hinge shaft  7  at a fixed position; and a female screw hole  12   c  for fixing a rod  20  by screw. 
     Especially as shown in  FIG.  3   ,  FIG.  4    and  FIG.  10   , third coupling members  15  are made up of seven elements having the same shape; they are configured to prevent the change in shaft-to shaft distances between a movable hinge shaft  6  and a first displaceable rotary shaft  13 , between this first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 , as well as between this second displaceable rotary shaft  14  and a fixed hinge shaft  7 . These third coupling members  15 ,  15  . . . are a plate-like elements having an oval shape in plan view, similar to remaining a first coupling member  9 , a second A coupling member  10 , a second B coupling member  11  and a second C coupling member  12 , but smaller than these; the third coupling members  15 ,  15  . . . are composed of seven such elements in total, but their number is not limited. Especially as in  FIG.  10   , where one representative of these third coupling members  15 ,  15  . . . is enlarged and shown, each two coupling holes  15   a ,  15   a  . . . and coupling holes  15   b ,  15   b  . . . are provided on it. Though not shown in detail, inner diameters of respective coupling holes  15   a ,  15   a  . . . and coupling holes  15   b ,  15   b  . . . are different in accordance with outer diameters of respective shaft portions of a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13 , and a second displaceable rotary shaft  14 , which are coupled to these holes. 
     As shown in  FIG.  4   ,  FIGS.  11 A and  11 B , a shaft-to-shaft distance stabilizing mechanism B between a movable hinge shaft  6  and a fixed hinge shaft  7  is made up of a pair of hook members  16 ,  17 . As in  FIGS.  11 A and  11 B , where one of them is enlarged and shown, these hook members  16 ,  17  respectively comprise coupling holes  16   a ,  17   a  and hook portions  16   b ,  17   b ; and these hook portions  16   b ,  17   b  always crossing each other hold a first small diameter portion  7   c  of the fixed hinge shaft  7 . 
     A synchronous rotation mechanism C for synchronously rotating a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14  is made up of third coupling members  15 ,  15  . . . as described above, as well as of a first gear portion  6   d , a second gear portion  7   d , a third gear portion  13   d  and a fourth gear portion  14   a , wherein these gear portions are respectively provided on the movable hinge shaft  6 , the fixed hinge shaft  7 , the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14  to mesh with each other, as shown in  FIG.  3    and  FIG.  4   . Outer diameters and gear ratios of these respective gear portions  6   d ,  7   d ,  13   d ,  14   a  may vary from one another. Moreover, this synchronous rotation mechanism C is not limited to the one in Embodiment, but can be replaced with the one using a belt. 
     Friction torque generation mechanisms F are of known structure, and as shown in  FIG.  3    and  FIG.  4   , made up of a first friction torque generation mechanism F 1 , a second friction torque generation mechanism F 2 , a third friction torque generation mechanism F 3  and a fourth friction torque generation mechanism F 4  respectively provided on a movable hinge shaft  6 , a fixed hinge shaft  7 , a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14 , and these are respectively made up of disc springs  18 ,  18 ,  18 ,  18  through which respective shafts (the movable hinge shaft  6 , the fixed hinge shaft  7 , the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14 ) are inserted; friction washers  19 ,  19 ;  19 ,  19 ;  19 ,  19 ;  19 ,  19 , wherein one pair each of these is provided for each disc spring  18 ,  18 ,  18 ,  18  to sandwich the latter; and fastening nuts  22 ,  22 ,  22 ,  22  screwed with respective male screw portions  6   i ,  7   i ,  13   h ,  14   f  of the respective shafts (the movable hinge shaft  6 , the fixed hinge shaft  7 , the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14 ). Insertion holes  19   a ,  19   a ;  19   a ,  19   a ;  19   a ,  19   a ;  19   a ,  19   a  provided on respective friction washers  19 ,  19 ;  19 ,  19 ;  19 ,  19 ;  19 ,  19  are deformed holes engaged with respective deformed shaft portions  6   h ,  7   h ,  13   g ,  14   e  of the respective shafts (the movable hinge shaft  6 , the fixed hinge shaft  7 , the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14 ); and respective insertion holes  18   a  of respective disc springs  18 ,  18 ,  18 ,  18  are all circular, though not shown. For the rest, in  FIG.  3    and  FIG.  4    reference numerals  23 ,  23 ;  23 ,  23  denote spacer rings, while reference numerals  24 ,  24  washers. It is noted that the first friction torque generation mechanism F 1 , the second friction torque generation mechanism F 2 , the third friction torque generation mechanism F 3  and the fourth friction torque generation mechanism F 4  are simply referred to as friction torque generation mechanisms, as stated above. 
     Next, reference is made to an arrangement of each of a first coupling member  9 , second coupling members  10 ,  11 ,  12  and third coupling members  15 ,  15  . . . . Especially as shown in  FIG.  2    to  FIG.  4    and  FIG.  6   , the first coupling member  9  first also functions as a lid body for a case portion A; and a guide long hole  9   a  and a first bearing hole  9   b  of the first coupling member  9  bear respective flange portions  6   a ,  7   a  of a movable hinge shaft  6  and a fixed hinge shaft  7 . Three second coupling members, i.e. a second A coupling member  10 , a second B coupling member  11  and a second C coupling member  12  are installed at predetermined intervals on a rear side of the first coupling member  9 , i.e. on the left side especially as in  FIG.  3   ; respective small diameter portions  6   f ,  7   f  of a movable hinge shaft  6  and a fixed hinge shaft  7  are inserted into bent guide long holes  10   a ,  11   a ,  12   a  and second bearing holes  10   b ,  11   b ,  12   b  provided on these second coupling members. Each of a third small diameter portion  13   f  and a second small diameter portion  14   d  of a first displaceable rotary shaft  13  and a second displaceable rotary shaft  14  are displaceably coupled and borne by these bent guide long holes  10   a ,  11   a ,  12   a.    
     A movable hinge shaft  6  and a second displaceable rotary shaft  14 , the second displaceable rotary shaft  14  and a first displaceable rotary shaft  13 , as well as a second displaceable rotary shaft  13  and a fixed hinge shaft  7  are respectively coupled to each other by third coupling members  15 ,  15 ,  15 ,  15 , and configured to avoid a change in mutual shaft-to-shaft distances. 
     Next, reference is made to the operation of respective components and mechanisms of the raising/lowering-type biaxial hinge  4  according to the invention, and particularly to the case that it is used in the dual-screen foldable tablet-type terminal device  1  shown in  FIG.  1   , wherein both of the display portions  1   a ,  2   b  are installed on the first casing  2  and the second casing  3 . 
     In this case, the raising/lowering-type biaxial hinge  4  according to the invention functions in the same manner as an ordinary biaxial hinge, when the second casing  3  is opened as shown in  FIG.  12 C  from the closed state of the first casing  2  and the second casing  3  shown in  FIG.  12 A , the fixed hinge shaft  7  attached to the second casing  3  is rotated, here the rotation drive force is transmitted via the second gear portion  7   d  to the third gear portion  13   d  provided on the first displaceable rotary shaft  13 , then to the fourth gear portion  14   a  of the second displaceable rotary shaft  14  meshed with the third gear portion  13   d , and to the movable hinge shaft  6  comprising the first gear portion  6   d  meshed with the fourth gear portion  14   a ; as the movable hinge shaft  6  is rotated in a direction contrary to the fixed hinge shaft  7 , the first casing  2  and the second casing  3  are opened from the closed state at 0 degree e.g. to 80 degrees, 180 degrees and 360 degrees, respectively as shown in  FIGS.  12 B,  12 C,  12 D ; these casings are stopped at any opening angle by the second friction torque generation mechanism F 2 , the third friction torque generation mechanism F 3 , the fourth friction torque generation mechanism F 4  and the first friction torque generation mechanism F 1  of the friction torque generation mechanisms F provided on respective shafts (the fixed hinge shaft  7 , the first displaceable rotary shaft  13 , the second displaceable rotary shaft  14  and the movable hinge shaft  6 ) to assure the operable state. When the first casing  2  and the second casing  3  once opened 360 degrees are closed, the movement contrary to what is described above takes place, the first casing  2  and the second casing  3  are closed to 0 degree at the beginning. 
     Next, reference is made to the operation of the raising/lowering-type biaxial hinge  4  according to the invention, in case that the terminal device is used like a notebook PC, using the keyboard panel prepared separately from the dual-screen foldable tablet-type terminal device. 
     As shown in  FIGS.  13 A to  13 C , the reference numeral  1   a  denotes the dual-screen foldable tablet-type terminal device with the keyboard panel  21 . The dual-screen foldable tablet-type terminal device  1   a  with the keyboard panel  21  is normally used simply as the dual-screen foldable tablet-type terminal device, but as shown in  FIGS.  14 A to  14 C , it is configured to enable inputs by key operations as in a notebook PC, with the separately prepared keyboard panel  21  being placed on the first casing  2 , the keyboard panel  21  and the first display portion  2   a  and/or the second display portion  3   a  can communicate with each other using proximity wireless communication such as Bluetooth®. 
     When the operator finishes inputting by key operations on the keyboard panel  21  and removes the keyboard panel  21  from the first casing  2 , it can be used again as it is as the dual-screen foldable tablet-type terminal device; when he carries the keyboard panel  21  together with him to move, he can carry the keyboard panel  21  as placed between the first casing  2  and the second casing  3  to make it compact and to prevent the keyboard panel  21  Therefore, in this case it is necessary to ensure that the second casing  3  can be closed as the keyboard panel  21  is placed on the first casing  2 . In such case, when the second casing  3  is closed toward the keyboard panel  21 , the rear end portion of the second casing  3  abuts against the rear end portion of the keyboard panel  21 . 
     When the second casing  3  is further closed toward the first casing  2  or the keyboard panel  21  from this state, the movable hinge shaft  6  and the fixed hinge shaft  7  are under the force for pulling them vertically, the raising/lowering-type biaxial hinge  4  slides downward, as its case portion A as well as the second casing  3  are lifted upward together with the fixed hinge shaft  7 , and the movable hinge shaft  6  moves inside the guide long hole  9   a  and the bent guide long holes  10   a ,  11   a ,  12   a  provided respectively on the first coupling member  9  and on the second A coupling member  10 , the second B coupling member  11  and the second C coupling member  12 . Due to this movement, a gap corresponding to the thickness of the keyboard panel  21  is generated between the first casing  2  and the second casing  3 , so that the first casing  2  and the second casing  3  can be closed, as shown in  FIG.  14 A . 
     In other words, when the second casing  3  is closed relative to the first casing  2 , the movable hinge shaft  6  and the fixed hinge shaft  7  are under the force for extending the shaft-to-shaft distance between them; therefore, the first displaceable rotary shaft  13  and the second displaceable rotary shaft  14  are coupled by respective coupling members  15 ,  15 ,  15 ,  15 , so that these shafts move obliquely downward inside the bent guide long holes  10   a ,  11   a ,  12   a  of the second A coupling member  10 , the second B coupling member  11  and the second C coupling member  12 , as shown in  FIG.  14 A . In this manner, the raising/lowering-type biaxial hinge  4  with the first casing  2  and the second casing  3  being closed as the keyboard panel  21  placed between them is equally in the state shown in  FIG.  14 A . 
     At the same time, the synchronous rotation mechanism C moves, and in this case the rotation of the fixed hinge shaft  7  is transmitted to the movable hinge shaft  6 . 
     When the second casing  3  closed as described above is opened again, the raising/lowering-type biaxial hinge  4  restores its original state from the predetermined opening and closing angle, as shown in  FIGS.  14 B and  14 C . 
     Furthermore, when the keyboard panel  21  is removed from the upper surface of the first casing  2 , the raising/lowering-type biaxial hinge  4  itself descends to resume its original shape of dual-screen foldable tablet  1  and the raising/lowering-type biaxial hinge  4  restore its original state. 
     As stated in the foregoing, a raising/lowering-type biaxial hinge according to the invention is suitably used as a hinge for opening and closing an ordinary dual-screen foldable tablet or a dual-screen foldable tablet comprising a separate keyboard panel; it further makes it possible to provide a dual-screen foldable tablet using such a raising/lowering-type biaxial hinge as well as a dual-screen foldable tablet comprising an attachable and detachable keyboard panel; and it is further suitably used as a hinge for a terminal device equally varying its thickness depending on its applications.