Patent Publication Number: US-2011075335-A1

Title: Biaxial hinge mechanism

Description:
TECHNICAL FIELD 
     The present invention relates to a biaxial hinge mechanism for opening and closing a monitor to unfold and fold the monitor and for making a rotation (autorotation) to change the orientation of the monitor. 
     BACKGROUND ART 
     Passenger cars in recent years include one having provided therein a monitor for a television, DVD, game, or the like, intended for a rear seat occupant. In a vehicle including three-row seats or opposed seats, the monitor is mounted on a ceiling of the vehicle. Preferably, such a monitor is arranged such that the orientation of the screen thereof can be changed according to a seating position of the occupant, that is, how the occupant is seating facing forward or backward, in a reclining position, or the like. Further, there arises such a request not only in a vehicle but also in a system including a monitor. 
       FIG. 7  shows a structure of a conventional biaxial hinge that opens and closes a monitor to unfold and fold the monitor, and rotates the monitor to change the orientation of the monitor.  FIG. 7  is a front view illustrating the state where the monitor is attached to the conventional biaxial hinge. The biaxial hinge is composed of a monitor rotating mechanism  100  for allowing a monitor  3  to rotate (autorotate) and a monitor opening and closing mechanism  200  for opening and closing the monitor  3 . The monitor opening and closing mechanism  200  allows the monitor  3  to rotate together with the monitor rotating mechanism  100  about a first rotation center axis (hereinafter referred to as a “first axis”) X, and the monitor rotating mechanism  100  allows the monitor  3  to rotate about a second rotation center axis (hereinafter, referred to as a “second axis”) Y. 
       FIG. 8  is an exploded perspective view of the monitor rotating mechanism  100  of the conventional biaxial hinge as shown in  FIG. 7 , and  FIG. 9A  is a sectional view of the monitor rotating mechanism  100 . A cylindrical boss  11  using the second axis Y as a central axis is provided on one face of the monitor  3 . The boss  11  has formed at the end thereof on the opposite side from the monitor  3 , D-cut sections  11   a  which are formed by flattening a portion of the outer peripheral face thereof, and a peripheral groove  11   c  which is formed by reducing in diameter the front end thereof. Further, a holding section  11   b  projecting from the outer peripheral face is formed therearound on the upper side of the D-cut sections  11   a.    
     The boss  11  is passed therethrough by a presser plate  12  and a leaf spring  13  having a ring shape, a sub-base  14 , a leaf spring  15  and a presser plate  16  also having a ring shape in this order. By crimping or caulking a fringe of the peripheral groove  11   c  of the boss  11  to form a crimped section  11   d , the boss  11  is fixed to the sub-base  14 . The sub-base  14  is secured to a base  21  of the monitor opening and closing mechanism  200  with screws  17 . 
     Around the inner peripheries of holes formed through the presser plates  12 ,  16 , and the leaf springs  13 ,  15  are formed straight line sections  12   a ,  13   a ,  15   a , and  16   a  for fitting with the D-cut sections  11   a  of the boss  11 . The D-cut sections  11   a  fit in the straight line sections  12   a ,  13   a ,  15   a , and  16   a , thus rotating the presser plates  12 ,  16 , and the leaf springs  13 ,  15  together with the boss  11  when the boss  11  is rotated. On the other hand, since a hole  14   a  bored through the sub-base  14  does not have a straight line section provided around the inner periphery thereof, the sub-base  14  is not rotated even when the boss  11  is rotated. 
     The presser plate  16  is formed so as to have an inner diameter that fits in the peripheral groove  11   c , and the presser plate  16  fits in the peripheral groove  11   c , thus restraining the presser plate from moving to the upside. Furthermore, the presser plate  16  is fixed to the peripheral groove  11   c , thus determining a holding width H ( FIG. 9A ) which is formed by the presser plate  16  and the holding section  11   b . In the portion of the holding width H are attached the presser plate  12 , the leaf spring  13 , the sub-base  14 , and the leaf spring  15 , and those components are sandwiched in the vertical direction by the holding section  11   b  and the presser plate  16 . 
     Engaging convexities  13   b ,  15   b  for engaging with engaging holes  14   b  of the sub-base  14  on the faces on the sub-base  14  side of the leaf springs  13 ,  15  are provided, respectively, and the engaging convexities  13   b ,  15   b  are pressed against the sub-base  14  by the elastic force of the leaf springs  13 ,  15 , respectively. The engaging convexities  13   b ,  15   b  rotates while sliding on the sub-base  14  with the convexities pressed against the sub-base, and engage in the engaging holes  14   b , thus positioning the monitor  3  at a predetermined angle with respect to the sub-base  14 . Otherwise, when the engaging convexities  13   b ,  15   b  are in the positions where the convexities do not engage in the engaging holes  14   b , the leaf springs  13 ,  15  are flexed by the height of the engaging convexities  13   b ,  15   b . To secure a clearance required for the boss  11  to rotate with respect to the sub-base  14 , the holding width H is adjusted to provide a clearance I each between the sub-base  14  and the leaf springs  13 ,  15  located on both sides of the sub-base. It is to be noted that the clearances I are not higher than the height to which the engaging convexities  13   b ,  15   b  project. 
     Therefore, since the monitor  3  can autorotate about the second axis Y with respect to the sub-base  14  using the boss  11 , and further the monitor is resiliently pressed against the sub-base  14  by the leaf springs  13 ,  15 , the monitor has suitable sliding resistance, and can autorotate requiring a suitable torque. 
     Moreover, the hinge device disclosed, e.g., in Patent Document 1 is arranged by passing a hinge main body through a cylindrical section provided across each end of two casings to rotatably connect the two casings to each other. The hinge main body has provided at the tip thereof, an engaging section having resilience, and the engaging section is arranged to resiliently engage with the cylindrical section. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         Patent Document 1: JP-A-2005-249067 
       
    
     SUMMARY OF THE INVENTION 
     Since the conventional hinge mechanism is arranged as described above, there is a problem such that in the biaxial hinge mechanism shown in  FIG. 7  to  FIG. 9A , the leaf springs  13 ,  15  are flexed by vibrations within the inclination of the boss  11  brought about by the clearances I, which causes the chatter of the monitor rotating mechanism  100 .  FIG. 9B  is a sectional view showing a state of the chatter when vibrations are transmitted to the monitor rotating mechanism  100  of the conventional biaxial hinge as shown in  FIG. 9A . Since the monitor rotating mechanism  100  is provided with the only one hinge connection section which is parallel to the second axis Y, the chatter of the boss  11  caused in the clearances I of the monitor rotating mechanism  100  directly brings about the swing J of the monitor  3 . Since the resilient leaf springs  13 ,  15  are flexed by transmission of vibrations, the inclination at the bottom of the boss  11  owing to the clearances I can cause the large swing J. 
     Further, in the conventional type hinge mechanism as disclosed in Patent Document 1, since the engaging section resiliently presses both the casings, the casings can be prevented from chattering in the direction of the hinge main body axis; however, the casings cannot be prevented from being flexed in the direction orthogonal to the axis of the engaging section. Therefore, there is a problem such that when vibrations are transmitted to the casings, the engaging section can be flexed to thus cause chatter. 
     Furthermore, when the aforementioned conventional hinge mechanism is applied to a monitor apparatus mounted in a vehicle, vibrations during operation causes chatter in the hinge mechanism to thus swing the monitor; consequently, there is a problem such that it becomes difficult to see the image thereof. 
     The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent a monitor rotating mechanism from being chattered by vibrations to restrain a monitor from being swung. 
     The biaxial hinge mechanism according to the present invention is composed of a monitor opening and closing mechanism for allowing a monitor to open and close with respect to a first rotation center axis, and a monitor rotating mechanism for allowing the monitor which is rotated in the open direction with respect to the first rotation center axis to rotate with respect to a second rotation center axis orthogonal to the first rotation center axis, and the biaxial hinge mechanism is arranged such that the monitor rotating mechanism includes a sub-base fixed to a base of the monitor opening and closing mechanism; a cylindrical boss of which one end is fixed to the monitor, and of which the other end is supported rotatably about the second rotation center axis by the sub-base; and a bush of which one end is fixed to the base of the monitor opening and closing mechanism and which is inserted into the boss from the other end side thereof to journal the boss. 
     According to the present invention, the bush fixed to the base is arranged so as to be inserted into the boss, which is rotatably supported by the sub-base, to journal the boss. Thus, the rigidity of the monitor rotating mechanism is improved, thus preventing the chatter caused by vibrations. As a result, the monitor  3  can be restrained from being swung. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view showing an operation of a monitor to which a biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the monitor closed. 
         FIG. 1B  is a schematic sectional view of the state shown in  FIG. 1A . 
         FIG. 1C  is a perspective view showing an operation of the monitor to which the biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the monitor opened 120 degrees. 
         FIG. 1D  is a perspective view showing an operation of the monitor to which the biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the monitor opened 90 degrees. 
         FIG. 1E  is a perspective view showing an operation of the monitor to which the biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the monitor reversed from the state shown in  FIG. 1C . 
         FIG. 1F  is a perspective view showing an operation of the monitor to which the biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the reversed monitor rotated 30 degrees from the state shown in  FIG. 1E . 
         FIG. 1G  is a perspective view showing an operation of the monitor to which the biaxial hinge mechanism in accordance with the first embodiment of the present invention is applied with the reversed monitor housed. 
         FIG. 2A  is a front view of the biaxial hinge mechanism in accordance with the first embodiment of the present invention. 
         FIG. 2B  is a perspective view of the biaxial hinge mechanism in accordance with the first embodiment of the present invention. 
         FIG. 3  is a perspective view of the biaxial hinge mechanism in accordance with the first embodiment of the present invention with a monitor rotating mechanism and a monitor opening and closing mechanism both disassembled. 
         FIG. 4  is a disassembled perspective view showing the monitor rotating mechanism of the biaxial hinge mechanism in accordance with the first embodiment of the present invention. 
         FIG. 5A  is a sectional view of the monitor rotating mechanism of the biaxial hinge mechanism in accordance with the first embodiment of the present invention, taken along the line M-M in  FIG. 2B . 
         FIG. 5B  is a sectional view of the monitor rotating mechanism of the biaxial hinge mechanism in accordance with the first embodiment of the present invention, taken along the line N-N in  FIG. 2B . 
         FIG. 6  is an explanatory view showing an operation of the monitor rotating mechanism of the biaxial hinge mechanism in accordance with the first embodiment of the present invention. 
         FIG. 7  is a front view showing a state where a monitor is attached to a conventional biaxial hinge. 
         FIG. 8  is a disassembled perspective view showing a monitor rotating mechanism of the conventional biaxial hinge. 
         FIG. 9A  is a sectional view showing the monitor rotating mechanism of the conventional biaxial hinge. 
         FIG. 9B  is a sectional view showing a state where vibrations have been transmitted to the monitor rotating mechanism of the conventional biaxial hinge. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will now be described with reference to the accompanying drawings in order to explain the present invention in more detail. 
     First Embodiment 
     A first embodiment of the present invention will next be described with reference to the drawings in detail. It should be appreciated that in the following explanation of the embodiment, parts which are the same as or equivalent to the constituent elements in the conventional art ( FIG. 7  to  FIG. 9B ) previously explained are designated by similar numerals, and these explanations will be omitted. 
     In the first embodiment, a biaxial hinge mechanism according to the present invention is applied to a monitor apparatus mounted on a ceiling of the interior of a vehicle.  FIG. 1A  to  FIG. 1G  are views showing a series of opening and closing, and autorotating operations of a monitor apparatus including a biaxial hinge mechanism in accordance with the first embodiment.  FIG. 2A  is a front view showing the biaxial hinge mechanism in accordance with the first embodiment to be employed in the monitor apparatus, and  FIG. 2B  is a perspective view of the biaxial hinge mechanism.  FIG. 3  is a perspective view of the biaxial hinge mechanism in accordance with the first embodiment with a monitor rotating mechanism  100  and a monitor opening and closing mechanism  200  both disassembled, and  FIG. 4  is a disassembled perspective view of the monitor rotating mechanism  100 .  FIG. 5A  is a sectional view of the monitor rotating mechanism  100 , taken along the line M-M in  FIG. 2B , and  FIG. 5B  is a sectional view of the mechanism, taken along the line N-N in  FIG. 2B .  FIG. 6  is an explanatory view showing an operation of the monitor rotating mechanism  100 , viewed from the direction L as shown in  FIG. 3 . 
     As shown in  FIG. 1A  to  FIG. 1G , a monitor apparatus  1  consists of a monitor housing case  2  serving as a monitor housing section mounted on a ceiling of a vehicle and a monitor  3  that can be rotated (opened and closed) to be unfolded and folded with respect to the monitor housing case  2 . A screen  3   a  is provided on one face of the monitor  3 . The monitor  3  is rotated about a first axis X provided at one end portion thereof to be opened with respect to the monitor housing case  2 , as shown in  FIG. 1C , for instance. In the state where the monitor is opened 90 degrees with respect to the monitor housing case  2  as shown in  FIG. 1D , the monitor  3  is reversed as shown in  FIG. 1E  when rotated 180 degrees about a second axis Y that is orthogonal to the first axis X and parallel to the screen  3   a  of the monitor  3 . Further, the monitor  3  can be housed in the monitor housing case  2  as shown in  FIG. 1G  even in the reversed state. It is to be noted that in the following explanations, regardless of the angle about the first axis X, the state where the monitor  3  is in a state prior to the rotation of the monitor about the second axis Y ( FIG. 1A  to  FIG. 1D ) is referred to as a normal state, and the state where the monitor is rotated 180 degrees about the second axis Y to be reversed ( FIG. 1E  to  FIG. 1G ) is referred to as a reversion state or reversed state regardless of the angle to which the monitor is opened about the first axis X. 
     A lock mechanism  4  for locking or unlocking the monitor  3  to or from the monitor housing case  2  is provided between the end portion of the monitor  3  and the monitor housing case  2 . A lock hole  5  serving as a lock member on one side of the lock mechanism  4  is formed in the middle of the end face on the tip side of the monitor  3 . As shown in  FIG. 1B , the lock hole  5  is provided on the second axis Y that is orthogonal to the first shaft X and passes through the center of the monitor  3  in the directions of the width and thickness thereof. On the side of the monitor housing case  2 , a lock pawl member  6  working as a lock member on the other side thereof and having a pawl  6   a  that can engage and disengage with the lock hole  5  is provided rotatably through a shaft  7 . The lock pawl member  6  has an operating section  6   b  provided on the opposite side thereof from the pawl  6   a  with respect to the shaft  7 , and a spring force for pushing the pawl  6   a  into the lock hole  5  by a spring  8  is imparted to the operating section  6   b . The operating section  6   b  has a button  9  provided on the opposite side thereof from the spring  8 , and the button  9  is exposed from the surface of the monitor housing case  2 . By pushing the button  9 , the lock pawl member  6  is rotated to disengage the pawl  6   a  from the lock hole  5 , and thereby the monitor  3  is opened downwardly about the first axis X. Further, when the monitor  3  is pushed into the monitor housing case  2 , the monitor  3  enters the monitor housing case  2  while rotating the pawl  6   a  and the lock pawl member  6  against the spring force of the spring  8 ; when the lock hole  5  comes the position of the pawl  6   a , the pawl  6   a  enters the lock hole  5  to lock the monitor  3 . The pawl  6   a  has an incline provided at the tip thereof to be easily rotatable when pushed by the monitor  3 . 
     In this context, the monitor housing case  2  has a rubber cushion  10  provided in a portion thereof against which the face (the portion in the front face of the monitor except the portion where the screen  3   a  is provided, and the back face  3   b  thereof) of the monitor  3  abuts. When the monitor  3  is housed therein, the face of the monitor  3  and the rubber cushion  10  are arranged to be in contact with each other, or keep a certain distance therebetween. Upon housing of the monitor  3 , the rubber cushion  10  works as a buffer when the monitor  3  is pressed in the monitor housing case  2 , and also prevents the monitor  3  housed therein from generating abnormal noise because of vibrations and being damaged thereby. 
     One example of the operation of the monitor apparatus  1  will be discussed with reference to  FIG. 1A  to  FIG. 1G .  FIG. 1A  and  FIG. 1B  illustrate the state where the monitor  3  is housed in the monitor housing case  2 . Under such a condition, the button  9  is pushed to disengage the pawl  6   a  of the lock pawl member  6  from the lock hole  5 , and the monitor  3  is rotated about the first axis X by the self-weight thereof to be opened.  FIG. 1C  shows the state where the monitor  3  is opened and rotated to the position where the screen  3   a  is suitable for a viewing (and listening) from the direction F (the position where the monitor is rotated 120 degrees from the closed state). Some positions suitable for the viewing are arranged to be selectable according to occupant&#39;s seating conditions.  FIG. 1D  illustrates the state where the monitor  3  is rotated 90 degrees with respect to the closed position. The monitor  3  is rotated (autorotated) about the second axis Y with the state as a reference position.  FIG. 1E  illustrates the state where the monitor  3  autorotates through 180 degrees with respect to the state as shown in  FIG. 1D . The monitor  3  can be positioned in a predetermined viewing position when rotated about the first axis X in the reversed state thereof.  FIG. 1F  shows the state where the monitor is rotated a predetermined angle (60 degrees with respect to the closed position) from the reversed state as shown in  FIG. 1E  to be positioned in a position suitable for a viewing from the direction B. Specifically, for example, this is the state where the position of the screen  3   a  is changed from the viewing position ( FIG. 1C ) for an occupant facing forwardly to the viewing position for an occupant facing backwardly in a vehicle room. Furthermore,  FIG. 1G  shows the state where the monitor  3  in the reversed state is housed in the monitor housing case  2  as it stands. The screen  3   a  is in a state housed in the ceiling, and this state provides a comfortable viewing, for example, when a seat is set in a reclining position by an occupant. 
     Referring to  FIG. 2A  to  FIG. 5B , the monitor rotating mechanism  100  of the biaxial hinge mechanism that achieves the above-described autorotating operation of the monitor  3  about the second axis Y will next be discussed. The monitor  3  has a flat rectangular shape, and has the screen  3   a  provided on one face thereof as mentioned above. A cylindrical boss  11  using the second axis Y as a central axis is crimped to the central portion of a top face  3   c  of the monitor  3 . On the other hand, a cylindrical rigid bush  34  having an outer diameter smaller than the inner diameter of the boss  11  by the dimension of a fit is secured to a base  21  of the monitor opening and closing mechanism  200 . As illustrated in  FIG. 3 , the bush  34  is inserted in the boss  11 , and a sub-base  14  united with the boss  11  is fastened to tapped holes  22  of the base  21  with screws  17 , thus connecting the monitor rotating mechanism  100  with the monitor opening and closing mechanism  200 . As shown in  FIG. 5A  and  FIG. 5B , the bush  34  is arranged to have a length in the direction of the second axis Y extending partway along the height of the boss  11 . Even if burrs or swellings are produced to form a swelling portion  35  upon crimping the boss  11  to the top face  3   c , when the bush  34  is arranged to have the length in the direction of the second shaft Y extending partway along the height of the boss, that is, have the dimension not abutting against the swelling portion  35 , the insertion of the bush  34  into the boss  11  can be completed; thus, there are no cases where the sub-base  14  is fixed to the base  21  in an incomplete insertion position. As a result, the rotational performance of the boss  11  to the bush  34  can be stabilized. 
     Moreover, a clearance K formed between the inner peripheral face of the boss  11  and the outer peripheral face of the bush  34  is slightly the dimension of a fit. For this reason, even if vibrations are transmitted to the biaxial hinge mechanism, the boss  11  is controlled on the level to be inclined with respect to the bush  34  within the range of the clearance K; thus, the chatter by flexing of leaf springs  13 ,  15  in a clearance I can be prevented. Consequently, the monitor  3  is not greatly swung in the direction orthogonal to the second axis Y. Further, the bush  34  is formed in a hollow through which a wiring member  37  such as a flexible printed board is passed. The wiring member  37  connects the monitor  3  with a main board (not shown) on the side of the monitor housing case  2  to send and receive electric signals. Furthermore, a groove  34   a  is provided along the outer peripheral face of the bush  34  near to the monitor  3 , and an O-ring (a viscoelastic member)  36  is fit in the groove  34   a . The O-ring  36  serves as a buffer when vibrations are transmitted to the biaxial hinge mechanism to prevent the generation of the collision noise of the boss  11  with the bush  34 . 
     Two stoppers  31  for restraining the monitor  3  from further rotation by abutting against an abutting section  32  on the side of a presser plate  16  are prepared protrudingly downward on the surface of the sub-base  14 . Further, the abutting section  32  and a protrusion  33  projecting outwardly in a radial direction are provided in the presser plate  16 . The abutting section  32  is formed with a length to abut against the stopper  31  of the sub-base  14 , while the protrusion  33  is formed with a length shorter than that of the abutting section  32  so as not to abut against the stopper  31 . 
     Referring to  FIG. 6 , the autorotating operation of the monitor rotating mechanism  100  will next be described.  FIG. 6  is a figure viewed from the back of the sub-base  14 , and the drawing of the monitor  3  connected to the monitor rotating mechanism  100  will be omitted. 
     The position of the abutting section  32  shown in  FIG. 6(   a ) is defined as “a reference position.” When the monitor  3  is in the reference position, the monitor is in a normal position. As shown in  FIG. 6(   a ), the abutting section  32  of the presser plate  16  is formed at the position where the abutting section abuts against the stopper  31  or at the position where a slight clearance exists therebetween when engaging convexities  13   b ,  15   b  of the leaf springs  13 ,  15  engage with engaging holes  14   b  of the sub-base  14 . Therefore, when the monitor  3  is autorotated from the reference position as shown in  FIG. 6(   a ), the boss  11  is rotated together with the monitor  3  while journaled by the bush  34 , and further, the abutting section  32  of the presser plate  16  fitting in the boss  11  is also rotated. At that time, since the protrusion  33  is shorter than the abutting section  32  in the radial length, no protrusion abuts against the stopper  31  ( FIG. 6(   b )). When the abutting section  32  is rotated 180 degrees from the reference position, that is, to the position shown in  FIG. 6(   c ), the engaging convexities  13   b ,  15   b  are engaged in the engaging holes  14   b  to be positioned, and even if the abutting section is pushed in an attempt to be further rotated in the same direction, the abutting section  32  is arranged not to be further rotated since the abutting section abuts against the stopper  31 . At that time, the monitor  3  autorotates through 180 degrees to be in the reversed position. 
     In such a way, the abutting section  32  abuts against the stopper  31 , thus limiting the rotation angle of the monitor  3  to 180 degrees and also regulating the rotatable direction to one direction. Therefore, the helix angle of a wiring member  37  passing through the interior of the boss  11  and the bush  34  is also regulated 180 degrees or less, thus preventing twist breakage of the wiring. 
     Referring to  FIG. 2A ,  FIG. 2B , and  FIG. 3 , the monitor opening and closing mechanism  200  of the biaxial hinge mechanism that achieves the opening and closing operation about the first axis X of the monitor  3  will next be discussed. 
     A pair of brackets  26  is provided in the monitor housing case  2  in a predetermined distance from each other. Meanwhile, the base  21  has a connection section  23  attached at each end thereof, and those connection sections  23  have their respective opening and closing shafts  24  provided on a straight line therein. The opening and closing shaft  24  has provided at the tip thereof an opening and closing leaf spring  25  attached therearound such that the spring is rotated integrally with the opening and closing shaft  24 . Further, the bracket  26  is attached between the opening and closing shaft  24  and the opening and closing leaf spring  25 . The opening and closing leaf spring  25  has an opening and closing engaging convexity  25   a  provided on the face of the one bracket  26  side thereof, and the opening and closing engaging convexity  25   a  is resiliently pressed against the bracket  26  by the elastic force obtained from the opening and closing leaf spring  25 . Meanwhile, the other bracket  26  has opening and closing engaging concavities  28   a ,  28   b , and  28   c  provided therein circumferentially in a predetermined distance. Those opening and closing engaging concavities  28   a ,  28   b , and  28   c  are used for positioning the monitor  3  in the predetermined viewing positions, and the distance (angle) therebetween is properly determined. 
     Therefore, the monitor  3  can be rotated about the first axis X with respect to the bracket  26  using the opening and closing shaft  24 , and moreover, the opening and closing leaf spring  25  is resiliently pressed against the bracket  26  by the opening and closing engaging convexity  25   a . Thus, the monitor has suitable sliding resistance, and is opened and closed requiring a suitable torque. 
     Further, an opening and closing stopper  27  is formed on a fringe on the opening and closing engaging concavity  28   a  side of the bracket  26 . The opening and closing stopper  27  is abutted against by the opening and closing leaf spring  25  attached at the tip of the opening and closing shaft  24  to thereby prevent the monitor  3  from being opened and closed beyond a predetermined amount. 
     It is to be noted that since the monitor opening and closing mechanism  200  includes two opening and closing shafts  24  parallel to the direction of the first shaft X, the mechanism has high vibration resistance, and does not easily chatter. 
     As discussed above, in accordance with the first embodiment, the monitor rotating mechanism  100  is arranged to include the sub-base  14  fixed to the base  21  of the monitor opening and closing mechanism  200 ; the cylindrical boss  11  of which one end is fixed to the top face  3   c  of the monitor  3 , and of which the other end is supported rotatably about the second axis Y by the sub-base  14 ; and the bush  34  of which one end is fixed to the base  21  and which is inserted into the boss  11  to journal the boss  11 . For this reason, if vibrations are transmitted to the biaxial hinge mechanism, the boss  11  is inclined with respect to the bush  34  only within the range of clearance K, thus enabling the leaf springs  13 ,  15  to be prevented from being flexed to chatter. As a result, the rigidity of the monitor rotating mechanism  100  is increased to prevent chatters by vibrations, which makes it possible to restrain swing of the monitor  3 . 
     Further, the bush  34  is formed having a length extending halfway along the length of the boss  11 . On that account, the bush  34  does not abut against the swelling section  35  of the boss  11 , and the bush  34  can be completely inserted in the boss  11 . Consequently, the rotational performance of the boss  11  to the bush  34  can be stabilized. 
     Furthermore, the groove  34   a  is provided along the outer peripheral face of the bush  34 , and the O-ring  36  is inserted in the groove  34   a . For this reason, if vibrations are transmitted to the biaxial hinge mechanism, the O-ring  36  acts as a buffer to enable the collision noise of the boss  11  with the bush  34  to be prevented from being generated. 
     Moreover, since the bush  34  is arranged to have a cylindrical shape, the wiring member  37  for connecting the monitor  3  with the main board can be passed through the bush  34 . 
     In this context, in accordance with the first embodiment discussed above, it is arranged that the groove  34   a  to be inserted by the O-ring  36  be inserted is provided along the outer peripheral face of the bush  34 ; however, it may be arranged that the boss  11  have a groove provided along the inner peripheral face thereof to insert an O-ring in the groove. 
     Besides, fluid with a high viscosity such as silicone oil may be placed in the groove in place of the O-ring. 
     INDUSTRIAL APPLICABILITY 
     As discussed above, the biaxial hinge mechanism according to the present invention, in order to prevent the chatter of the monitor rotating mechanism caused by vibrations and thereby restrain the monitor from swinging, is composed of the monitor opening and closing mechanism and the monitor rotating mechanism, and further the biaxial hinge mechanism is arranged such that the monitor rotating mechanism includes the sub-base, the cylindrical boss, and the bush for journaling the boss. Thus, the biaxial hinge mechanism is suitable for use in a biaxial hinge mechanism or the like used for opening and closing a monitor mounted on an automobile.