Patent Publication Number: US-2009217486-A1

Title: Hinge device and electronic apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-048648, filed on Feb. 28, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One embodiment of the invention relates to a hinge device and an electronic apparatus, and more particularly to a hinge device having a mechanism for increasing the torque. 
     2. Description of the Related Art 
     Conventionally, an electronic apparatus such as a portable computer, is configured of a main body unit having a keyboard, and a display unit including a liquid crystal display. The display unit is rotatably supported by a hinge device on the main body unit. 
     The hinge device has a first bracket, a second bracket and a hinge shaft. One end of the hinge shaft is rotatably supported on the first bracket, and the other end of the hinge shaft is fixed to the second bracket. Therefore, the first bracket and the second bracket can be relatively rotated around the axis of the hinge shaft. 
     In recent years, as a liquid crystal display device of larger size is favorable, the display unit of the portable computer also tends to be larger in size. Accordingly, the hinge device is required to produce a larger rotational torque along with the larger size of the display device. 
     JP-A-2005-76790 (see page 10, FIG. 3) discloses a technique for increasing the rotational resistance by providing a rotational resistance increasing elastic portion formed of a leaf spring between a relative rotation portion and a second mounting portion like a case relatively rotated around a rotational shaft portion. 
     However, the leaf spring of JP-A-2005-76790 has necessarily the shape incorporated into the second mounting portion, whereby the shape of the leaf spring itself is complicated. Accordingly, there may be a problem that the hinge device has a complex constitution as a whole. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. 
         FIG. 1  is an exemplary perspective view of the portable computer according to an embodiment of the present invention; 
         FIG. 2  is an exemplary perspective view, partially broken away, of the portable computer; 
         FIG. 3  is an exemplary perspective view showing a hinge device  21 ; 
         FIG. 4  is an exemplary perspective view showing the hinge device  21 ; 
         FIG. 5  is an exemplary exploded view showing the hinge device  21 ; 
         FIG. 6  is an exemplary exploded view showing the hinge device  21 . 
         FIGS. 7A and 7B  are exemplary views showing a state where a display unit  3  is closed on the main body unit  2 ; 
         FIGS. 8A and 8B  are exemplary views showing a state where the display unit  3  is opened up to 90° with respect to the main body unit  2 ; 
         FIGS. 9A and 9B  are exemplary views showing a state where the display unit  3  is opened up to 135° with respect to the main body unit  2 ; and 
         FIG. 10  is an exemplary perspective view showing a hinge shaft  230 . 
     
    
    
     DETAILED DESCRIPTION  
     Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, there is provided a hinge device including: a first bracket; a first cam member having a first cam face at one side, wherein the other side engages with the first bracket; a second cam member having a second cam face at one side, the second cam face provided correspondingly to the first cam face; a disc spring that urges the second cam member on the other side thereof, which is opposite to the second cam face; a first friction plate provided correspondingly to the first bracket, the first friction plate disposed oppositely to the first cam member with respect to the first bracket; a stopper member provided correspondingly to the first friction plate on one side thereof, the stopper member disposed oppositely to the first bracket with respect to the first friction plate, the stopper member engaged with the first bracket; and a hinge shaft having a shaft that rotatably supports the first bracket, the first cam member, the disc spring, and the stopper member, and that unrotatably supports the second cam member and the first friction plate. 
     Embodiment of the Invention 
     The embodiment of the present invention will be described below with reference to the drawings in connection with a portable computer.  FIG. 1  shows a portable computer  1  as an electronic apparatus. This portable computer  1  is configured of a main body unit  2  and a display unit  3 . 
     The main body unit  2  has a first casing  4  made of resin. This first casing  4  has a base  5  and a top cover  6 , and is formed in the shape of a flat box. 
     An outer face of the top cover  6  exposed outside has an upper wall  4   b  and a side wall  4   c.  At a back end portion of the top cover  6 , a pair of leg portions  15   a  and  15   b  are spaced in the width direction of the first casing  4 . 
     The display unit  3  includes a liquid crystal display portion  14  having a second casing  13  and a screen  14   a  received within the second casing  13 . The second casing  13  is composed of an LCD cover  16  and an LCD mask  17 , and an opening portion  18  for display is provided on a front wall of the LCD mask  17 . This opening portion  18  has a size extending over most part of the front wall, and the screen  14   a  of the liquid crystal display portion  14  is exposed outward of the display unit  3  through this opening portion  18 . 
     The first casing  4  includes a keyboard mounting portion  8  and a touch pad  19 . The keyboard mounting portion  8  is a rectangular recess portion opening to the upper face of the upper wall  4   b,  and bears a keyboard  10 . The touch pad  19  is provided to be exposed through an opening portion  12   c  located in front of the keyboard  10  on the upper wall  4   b  of the top cover  6 , and has switches  19   a  and  19   b.    
     The display unit  3  has a pair of connecting concave portions  23 A and  23 B at one end portion thereof. Each of the connecting concave portions  23 A and  23 B is composed of a concavity that opens forward, downward and backward of the display unit  3 . The connecting concave portions  23 A and  23 B are spaced in the width direction of the display unit  3 , and led to the leg portions  15   a  and  15   b  of the first casing  4 . And these connecting concave portions  23 A and  23 B are rotatably supported by the hinge devices  21  and  22  at the back end portion of the first casing  4 , as will be described later. 
     Therefore, the display unit  3  can be rotated between a closed position where it is flattened to cover the upper wall  4   ba  and the keyboard  10  from above and an open position where it is raised to expose the upper wall  4   b  and the keyboard  10 . In  FIG. 1 , it should be noted that the computer  1  is illustrated in the open position. 
       FIG. 2  is a perspective view, partially broken away, of the portable computer according to the embodiment of the invention.  FIGS. 3 and 4  are perspective views showing the hinge device  21 . 
     The base  5  of the first casing  4  has a pair of hinge support portions  20   a  and  20   b  in the areas for supporting the first hinge device  21  and the second hinge device  22 . In  FIG. 2 , a hinge support portion  20   a  is only illustrated. A basic structure around the hinge is almost equivalent for both the hinge support portions  20   a  and  20   b,  because they are disposed in bilateral symmetry. In the following, the hinge support portion  20   a  is only explained, and the hinge support portion  20   b  is not explained except for specific cases. 
     The hinge support portion  20   a  rotatably supports the base  5  and the LCD cover  16  by the first hinge device  21  made of metal, fastened by a screw  23  (not shown). The hinge support portion  20   a  has a screw fixing portion  200  and a positioning portion  201 . 
     The first hinge device  21  has a first bracket  210  fastened by a screw to the hinge support portion  20   a  of the base  5 , and the first bracket  210  has a screw through hole  211  for passing the screw  23  and a positioning hole  212 , as shown in  FIGS. 3 and 4 . 
     The hinge device  21  is provided to link between the base  5  and the LCD cover  16 , as shown in  FIG. 2 . More specifically, the first bracket  210  of the hinge device  21  is fixed to the hinge support portion  20   a  in the base  5 . The hinge device  21  is fastened to the screw fixing portion  200  of the base  5  by the screw inserted through the screw through hole  211  of the first bracket  210  (the screw is not shown). The positioning portion  201  is inserted into the positioning hole  212  of the first bracket  210  to position the first bracket  210 . 
     On the other hand, a second bracket  240  of the hinge device  21  is fixed to a hinge support portion  20 A in the LCD cover  16 . The second bracket  240  is fixed to the first hinge device  21 , and connected with the LCD cover  16  by a screw, as shown in  FIG. 2 . Herein, the hinge support portion  20 A is an area for supporting the first hinge device  21 , and located in an area opposed to the hinge support portion  20   a  or in the neighborhood of the opposed area, when the display unit  3  is in the closed position. This positional relation depends on the shaft length of a hinge shaft  230 . 
     The hinge support portion  20 A has the screw fixing portion  200  and the positioning portion  201 . In  FIG. 2 , the screw fixing portion  200  in the hinge support portion  20 A is not shown. 
     The second bracket  240  has a shaft fixing portion  241  fixed to the hinge shaft  230 , an arm  242  integrated with the shaft fixing portion  241 , an LCD cover fixing piece  243  provided at the top end of the arm  242 , and a screw through hole  244  for passing a screw fixing the second bracket  240  to the LCD cover of the display unit  3 . The LCD cover  16  is fastened by the screw passed through the screw through hole  244  in a state where the LCD cover fixing piece  243  is engaged at the screw fastened position. 
     The first hinge device  21  has a rotation regulating portion for regulating the rotation of the shaft based on a relative displacement between the first bracket  210  and the second bracket  240  on the shaft in the axial direction away from the second bracket  240  received within the display unit  3 . The rotation regulating portion is mainly composed of a stopper member  219  and a pin  230   a  as will be described later, and regulates the rotation of the display unit  3  at a certain angle in the open position. Also, the first hinge device includes a cam mechanism portion for holding the hinge shaft to prevent the display unit  3  from being rotated in the opening direction in the closed position. The cam mechanism portion is mainly composed of a first cam member  215  and a second cam member  216 . 
     Referring to  FIGS. 3 to 6 , a structure of the first hinge device  21  will be described below in detail. 
       FIGS. 5 and 6  are the exploded views of the hinge device  21 . The hinge device  21  has the first bracket  210 , the first cam member  15 , the second cam member  216 , a plurality of disc springs  217 , a first and a second friction plates  218 A and  218 B, the stopper member  219 , a fixing plate  220 , the hinge shaft  230 , and the second bracket  240 . In  FIGS. 5 and 6 , the second bracket  240  is not shown. For the hinge device  21  as shown in  FIGS. 5 and 6 , the portion except for the disc springs  217  is formed of stainless steel (SUS), and the first cam member  215  and the second cam member  216  are parkerized as a surface treatment to increase wear resistance. 
     Each element of the first hinge device  21  will be described below. 
     The first bracket  210  has a bracket main body  210   a , base fixing pieces  213  and  214 , and a cam fixing piece  210   b . The base fixing pieces  213  and  214  are positioned and fastened by screw or the like in the hinge support portion  20   a  of the base  5 . Also, the cam fixing piece  210   b  has a concave portion  210   b A. The first bracket  210  has a circular hole portion  210 A having a larger area than the cross section of a first shaft  221 A, and attached to the first shaft  221 A to be rotatable around the first shaft  221 A. Also, the first bracket  210  has a hole portion  210   c  in the shape of rectangular cross section that is equivalent to the cross section of an engagement piece  219 C in the bracket main body  210   a.    
     The first cam member  215  has a cam face  215   a  at one end of cylindrical shape, and an engagement piece  215 B at the other end. The cam face  215   a  is composed of a convex face  215   c  and a flat face  215   d.  The engagement piece  215 B is engaged in a concave portion  210   b A of the cam fixing piece  210   b  to regulate the relative rotational motion with the first bracket  210 . The cam face  215   a  of the first cam member  215  and a cam face  216   a  of the second cam member  216  as will be described later are contacted to fulfill a function of cam. Accordingly, the first cam member  215  fulfills the function of a cam member on the stationary side. The first cam member  215  has a hole portion  215 A in the shape of rectangular cross section that is equivalent to the cross section of the shaft  221 , and attached to the first shaft  221 A to regulate the rotation around the first shaft  221 A. 
     The second cam member  216  has the cam face  216   a  composed of a convex face  216   c  and a flat face  216   d,  and the flat face  216   d  has the shape engaged with the convex face  215   c  of the cam face  215   a.    
     The convex face  215   c  is formed with a smooth curved face at the corner portion. The force of torque can be adjusted by adjusting the angle of this curved face. The second cam member  216  has a hole portion  216 A in the shape of rectangular cross section that is equivalent to the cross section of the shaft  221 , and is attached to the first shaft  221 A to regulate the rotation around the first shaft  221 A. 
     The disc springs  217  apply an elastic force to the second cam member  216 . The disc springs  217  are formed of high tensile steel to have the cross section like a gentle curve, and attached to the shaft  221  so that the concave faces  217   a  of two disc springs  217  may be confronted and combined to form a pair. Each disc spring  217  has a circular hole portion  217 A having a larger area than the cross section of the first shaft  221 A, and is attached to the first shaft  221 A to be rotatable around the first shaft  221 A. One pair of disc springs  217  are deformed according to an external force to cause a resiliency, if the external force is applied in a direction compressing the convex face  217   b.  In this embodiment, three pairs of disc springs  217  are employed. 
     The first friction plate  218 A is a flat plate having a circular cross section, and in the center has a hole portion  218 AA in the shape of rectangular cross section that is equivalent to the cross section of the first shaft  221 A, and is attached to the first shaft  221 A to regulate the rotation around the shaft  221 . The first friction plate  218 A has a hole portion  218   a  for supplying grease to a contact surface between the stopper member  219  and the first bracket  210 . The contact surface is supplied with a proper amount of oil owing to grease supplied through the hole portion  218   a  to suppress the increasing sliding resistance. The first friction plate  218 A is provided between the stopper member  219  and the first bracket  210  through the shaft  221 . 
     The stopper member  219  has a stopper  219 A, a stopper main body  219 B and an engagement piece  219 C. The engagement piece  219 C is inserted into an engagement hole portion  210   c  provided in the bracket main body  210   a  of the first bracket  210 . Thereby, the stopper main body  219 B confronts and contacts the first friction plate  218 A. The stopper main body  219 B has a circular hole portion  219   b  having a larger area than the cross section of the first shaft  221 A, and is attached to the first shaft  221 A to be rotatable around the first shaft  221 A. The stopper member  219  is located on the outer periphery of the second friction plate  218 B by folding the stopper  219 A. The stopper  219 A is regulated from being rotated because the pin  230   a  ( FIG. 3 ) of the hinge shaft  230  contacts the side face of the stopper  219 A with the rotation based on a relative displacement around the hinge shaft  230  between the first bracket  210  and the second bracket  240 . 
     The second friction plate  218 B has the same shape as the first friction plate  218 A. The second friction plate  218 B is provided between the stopper member  219  and a first flange member  231 A as will be described later. 
     Thereby, a frictional force occurs on the friction face not only between the first cam member  215  and the second cam member  216 , but also between the second friction plate  218 B and the stopper member  219 , between the stopper member  219  and the stopper  219 A, and between the first friction plate  218 A and the first bracket  210 . Accordingly, a larger torque can be produced than only between the first cam member  215  and the second cam member  216 . 
     The fixing plate  220 , which has a columnar shape, in the center has a hole portion  220 A in the shape of rectangular cross section that is equivalent to the cross section of the first shaft  221 A, and is attached to the first shaft  221 A to regulate the rotation around the shaft  221 . The fixing plate  220  is fixed with a fixing portion  222  configured of caulking with the first shaft  221 A passing through the hole portion  220 A. 
       FIG. 10  is a view showing the hinge shaft  230 . The hinge shaft  230  has a first shaft  221 A, a second shaft  221 B and a third shaft  221 C, as shown in  FIG. 10 . 
     The first shaft  221 A has the shape of rectangular cross section, and supports coaxially the second friction plate  218 B, the stopper member  219 , the first friction plate  218 A, the first bracket  210 , the first cam member  215 , the second cam member  216 , the disc springs  217  and the fixing plate  220 . 
     The second shaft  221 B has a larger cross section than the first shaft  221 A, and is like a crank as a whole. 
     The third shaft  221 C has the shape of rectangular cross section one size larger than the first shaft  221 A. The third shaft  221 C securely supports the second bracket  240 . 
     The first flange  231 A is provided between the first shaft  221 A and the second shaft  221 B. The first flange  231 A receives the second friction plate  218 B. Also, the pin  230   a  is provided on the side face of the first flange  231 A. 
     A second flange  231 B is provided between the second shaft  221 B and the third shaft  221 C. The second flange  231 B receives the second bracket  240  securely supported on the third shaft  221 C. The first shaft  221 A, the first flange  231 A, the second shaft  221 B, the second flange  231 B and the third shaft  221 C are integrally formed. 
     (Increasing Torque) 
     The cam mechanism portion of the hinge device  21  is configured between the first cam member  215  and the second cam member  216 , as previously described. This cam mechanism portion holds the first bracket  210  and the second bracket  240  at a certain angle based on a face contact between the cam face  215   a  of the first cam member  215  and the cam face  216   a  of the second cam member  216 .  FIGS. 3 and 4  show the state where the cam face  215   a  and the cam face  216   a  are engaged together by convex and concave. 
     The first shaft  221 A rotatably supports the stopper  219 A, the first bracket  210 , the disc springs  217 , and the first cam member  215 . Also, the first shaft  221 A supports the first friction plate  218 A, the second friction plate  218 B, the second cam member  216 , and the fixing plate  220  slidably in the axial direction. 
     With the first hinge device  21  configured as the above, a larger torque can be produced than the torque amount only between the first cam member  215  and the second cam member  216 . That is, in this embodiment, the first friction plate  218 A and the second friction plate  218 B are provided on both sides of the stopper member  219 . Thereby, a frictional force occurs on the friction face not only between the first cam member  215  and the second cam member  216 , but also between the second friction plate  218 B and the stopper member  219 , between the stopper member  219  and the stopper  219 A, and between the first friction plate  218 A and the first bracket  210 . 
     More specifically, if an operation of closing the display unit  3  on the main body unit  2  or opening the display unit  3  (rotation operation) is performed, the second bracket  240  fixed to the LCD cover  16  in a part of the display unit  3  is also rotated. Since the second bracket  240  is securely supported by the hinge shaft  230 , the first shaft  221 A in a part of the hinge shaft  230  is rotated with respect to the first bracket  210 . 
     Herein, the stopper member  219  is not rotated with respect to the first bracket  210 , because the engagement piece  219 C is engaged in the engagement hole portion  210   c.  However, the first friction plate  218 A and the second friction plate  218 B are rotated along with the rotation of the first shaft  221 A, because the hole portion  218 AA and the hole portion  218 BA have the same shape as the cross-sectional shape of the first shaft  221 A. That is, frictional resistance occurs between the face  218 Ba and the face  219 Bb. 
     Similarly, frictional resistance occurs between the face  219 Ba and the face  218 Ab, and between the face  218 Aa and the face  210   bb.    
     Accordingly, the first hinge device  21  has not only the torque in the cam mechanism between the first cam member  215  and the second cam member  216 , but also frictional resistance in other three portions, increasing the torque of the first hinge device  21  as a whole. 
     Accordingly, when the display unit  3  has a larger size, it is possible to produce a desired torque suitable for the display unit  3  by applying the hinge device of this embodiment. 
     Operation of this Embodiment 
     In the portable computer  1  of this configuration, the operation of the hinge device  21  in opening the display unit  3  with respect to the main body unit  2  from the closed state will be described below. 
       FIGS. 7A and 7B  show a state where the display unit  3  is closed on the main body unit  2 , in which  FIG. 7A  is a schematic view showing the state of the hinge device, the display unit and the main body unit, and  FIG. 7B  is a schematic view showing the state of the cam mechanism portion for the hinge device in  FIG. 7A . For the cam mechanism portion of  FIG. 7B , the schematic view shows the first cam member  215  and the second cam member  216  for the hinge device  21  as seen in the horizontal direction from the side of the keyboard. 
     When the display unit  3  is closed on the main body unit  2 , the angle made by the display unit  3  and the main body unit  2  with the shaft  221  as the rotation axis is about 0°, as shown in  FIG. 7A . At this time, the cam face  215   a  of the first cam member  215  and the cam face  216   a  of the second cam member  216  are partially contacted, as shown in  FIG. 7B . 
     In the state as shown in  FIG. 7B , a torque occurs in the direction urging the convex and concave engagement with the flat face  216   d  (the direction closing the display unit  3 ), owing to the shape of gentle curved face on the corner portion of the convex face  215   c.    
     Thereby, since the torque in the closing direction with the first shaft  221 A as the rotation axis is applied to the display unit  3 , the display unit  3  is not opened inadvertently. Though the angle (inclination of the display unit  3 ) when the convex face  215   c  and the flat face  216   d  are engaged by convex and concave is set at −15° in this embodiment, the torque in the closing direction occurs on the first shaft  221 A under the action of the cam mechanism portion if the inclination of the display unit  3  is 5 mainly or less. 
     In this embodiment, the first friction plate  218 A and the second friction plate  218 B are provided on both faces of the stopper member  219 . Thereby, a frictional force occurs on the friction face not only between the first cam member  215  and the second cam member  216 , but also between the second friction plate  218 B and the stopper member  219 , between the stopper member  219  and the stopper  219 A, and between the first friction plate  218 A and the first bracket  210 . Accordingly, a larger torque can be produced than only between the first cam member  215  and the second cam member  216 . Accordingly, when the display unit  3  has a larger size, a desired torque can be produced by applying the hinge device of this embodiment. 
       FIGS. 8A and 8B  show a state where the display unit  3  is opened up to 90° with respect to the main body unit  2 , wherein  FIG. 8A  is a schematic view showing the state of the hinge device, the display unit and the main body unit, and  FIG. 8B  is a schematic view showing the state of the cam mechanism portion for the hinge device in  FIG. 8A . 
     When the display unit  3  is opened up to 90° with respect to the main body unit  2  as shown in  FIG. 8A , a contact portion  250  between the convex face  215   c  and the convex face  216   c  has a larger area than in  FIGS. 7A and 7B , so that the face contact resistance is smaller than in  FIGS. 7A and 7B , as shown in  FIGS. 8A and 8B . Thereby, the display unit  3  can be rotated around the shaft  221  as the rotation axis with a smaller external force. 
       FIGS. 9A and 9B  show a state where the display unit  3  is opened up to 135° with respect to the main body unit  2 , in which  FIG. 9A  is a schematic view showing the state of the hinge device, the display unit and the main body unit, and  FIG. 9B  is a schematic view showing the state of the cam mechanism portion for the hinge device in  FIG. 9A . 
     When the display unit  3  is opened up to 135° with respect to the main body unit  2  as shown in  FIG. 9A , the stopper  219 A provided in the stopper member  219  contacts the pin  230   a  provided in the first flange  231 A of the hinge shaft  230 . Thereby, the rotation of the shaft  221  is regulated, so that the angle of the display unit  3  is kept at 135°.