Abstract:
A two-way auto-locking tablet PC hinge is described. The two-way auto-locking tablet PC hinge includes a hinge base, a central rotational frame, a shaft, a fixing bracket, a rotational cam, a fixed cam, and two positioners. The fixing bracket, the rotational cam, and the fixed cam are configured on the shaft. A monitor of the tablet PC is fixed on the fixing bracket and the hinge base is fixed on a tablet PC base. The positioners are composed of protrusion blocks and concaves and are axially symmetrically formed on the fixed cam and the rotational cam respectively. When the monitor is parallel to the tablet PC base, the protrusion blocks are engaged with the concaves correspondingly, thereby locking the monitor on the tablet PC.

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Taiwan Application Serial Number 94209564, filed Jun. 8, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     FIELD OF THE INVENTION 
     The present invention generally relates to a tablet personal computer hinge. More particularly, the present invention relates to a two-way auto-locking tablet personal computer hinge. 
     BACKGROUND OF THE INVENTION 
     Due to rapid developments in electrical technologies and computer industries, notebook computers are gradually becoming smaller and lighter with each passing day. Notebooks with portable size and weight have been granted an enormous increase in processing speed, and therefore notebook computers have become a popular electrical product. Since notebook computers possess convenient portability and powerful calculation ability, they have become required equipment for most businessmen. 
     In different operation environments, the notebook computer has to provide different display angles to enhance its demonstration capabilities. However, due to the conventional restricted display angle range, the notebook computer cannot provide a clear image to all viewers. In addition, due to software and hardware improvements, a tablet personal computer (Tablet PC) has been provided that combines the notebook computer with a hand-writable input device on the display. The tablet PC is changing the input habits of computer users and is advancing the information industry beyond a new milestone. A dual-purpose tablet PC with high processing performance combines the hand-writable input device on the display panel and the keyboard input of the notebook computer. 
     The dual-purpose tablet PC provides a humanized input interface for users who usually work in a mobile environment. The display of a dual-purpose tablet PC can rotate about 180 degrees so that viewers around the tablet PC can easily see the information and images on the display. 
     As the display of the dual-purpose tablet PC is able to rotate on the tablet PC, effectively fixing the display on the tablet PC is very important. Therefore, there is a need to design a fixing device for effectively fixing the display on the dual-purpose tablet PC. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a display of the tablet PC without a hook exposed thereon yet able to be locked on a base of the tablet PC. 
     It is another object of the present invention to provide a two-way auto-locking hinge for a tablet PC so that a display of the tablet PC can be quickly and easily locked or rotated regardless of the display being closed or under a handwriting input mode. 
     To accomplish the above objectives, the present invention provides a two-way auto-locking tablet PC hinge. The two-way auto-locking tablet PC hinge includes a hinge base, a central rotational frame, a shaft, a fixing bracket, a rotational cam, a fixed cam, and two positioners. The hinge base is coupled to a base of a tablet PC and the central rotational frame is rotatably coupled to the hinge base. The shaft is fixed on the central rotational frame and the fixing bracket is rotatably coupled to the shaft. A display of the tablet PC is fixed on the fixing bracket, and the rotational cam is rotatably coupled to the shaft and is fixed on the fixing bracket to synchronously rotate with the display. The fixed cam can engage with the rotational cam by the two positioners and is slidably coupled to the shaft. 
     The positioners are symmetrically formed between the rotational cam and the fixed cam to lock the rotational cam for fixing the display when the display is parallel to the base. Each of the positioners is composed of a protruding block and a concave. The protruding block is preferably formed on the rotational cam and the concave is preferably formed on the fixed cam to engage with the protruding block correspondingly when the display is parallel to the base, thereby locking the display to the base at 0, 180, or 360 degrees. 
     The two-way auto-locking tablet PC hinge further includes a spring washer coupling to the shaft to push the fixed cam toward the rotational cam so as to automatically engage the concave of the fixed cam with the protruding block of the rotational cam and lock the display when the concave is close to the protruding block. The two-way auto-locking tablet PC hinge further includes an auxiliary bracket rotatably coupling to the shaft, and the auxiliary bracket has an auxiliary bracket protrusion to couple to a fixing bracket opening of the fixing bracket to allow the auxiliary bracket to slide on the shaft and support the fixing bracket. In addition, two friction washers slidably coupling to the shaft are preferably disposed on two sides of the auxiliary bracket to increase a frictional force while rotating the fixing bracket and the auxiliary bracket. 
     The shaft further includes a shaft fixing surface, and the fixed cam and the friction washers further include a cam fixing surface and friction washer fixing surfaces respectively, thereby enabling the fixed cam and the friction washers to slide on the shaft without rotations. 
     Accordingly, the auto-locking tablet PC hinge of the present invention can lock either face of the display on the base of the tablet PC without any exposed hook. The auto-locking mechanism is hidden in the hinge and provides the frictional force for positioning the display. Hence, the two-way auto-locking tablet PC hinge of the present invention can allow the display be quickly and easily opened or closed in various conditions. The two-way auto-locking tablet PC hinge of the present invention not only allows the user to conveniently operate the display of the tablet PC but also allows the display to stably fix on the base of the tablet PC. Therefore, the users can operate the tablet PC more quickly and reliably. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention are more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an exploded view of a two-way auto-locking tablet PC hinge according to the present invention; and 
         FIGS. 2A to 2C  are partial enlarged views of the two-way auto-locking tablet PC hinge according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description is of the best presently contemplated mode of carrying out the present invention. This description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined by referencing the appended claims. 
       FIG. 1  illustrates an exploded view of a two-way auto-locking tablet PC hinge according to the present invention. The two-way auto-locking tablet PC hinge according to the present invention includes a hinge base  110 , a central rotational frame  120 , a fixing bracket  130 , a shaft  210 , and an auto-locking mechanism  100 . The hinge base  110  is fixed on the base of a tablet PC and the fixing bracket  130  is coupled to a display of the tablet PC. The shaft  210  is coupled to the central rotational frame  120  and the fixing bracket  130  is rotatable on the shaft  210 . The central rotational frame  120  can rotate on the hinge base  110  so that the display can be rotated on the base of the tablet PC. 
     The display  20  fixed on the fixing bracket  130  can therefore rotate around the shaft  210  to open or close the display  20  from the base  10  of the tablet PC  30 . In addition, the display  20  can utilize the central rotational frame  120  to rotate on the hinge base  110  and the base  10  of the tablet PC  30 . Accordingly, the display  20  can easily adjust a vertical angle and a horizontal angle on the tablet PC  30 . 
     The auto-locking mechanism  100  further includes a rotational cam  140 , a fixed cam  150 , a spring washer  160 , friction washers  170 , an intermediate washer  174  and a threaded nut  190 . One end of the rotational cam  140  is fixed with the fixing bracket  130  and another end thereof is coupled to the fixed cam  150  to provide the two-way auto-locking functionality for the display of the tablet PC. The spring washer  160  and the friction washer  170  are coupled to the shaft  210  and disposed on another side of the fixed cam  150  opposite to the rotational cam  140 . In addition, a threaded nut  190  is fixed to the shaft  210  to tighten the foregoing components on the shaft  210 . After the foregoing components are coupled on the shaft  210 , the auto-locking mechanism  100  is similarly formed on the left side of  FIG. 1  as the assembled auto-locking mechanism  200 . 
     The spring washer  160  provides pressure on the fixed cam  150  for tightly coupling the fixing cam  150  to the rotational cam  140 . Accordingly, the display of the tablet PC can be laid and locked on the base of the tablet PC with the auto-locking mechanism  100  when the display faces up or down and closes on the base of the tablet PC. 
     In the central portions of the fixed cam  150  and the friction washer  170 , the fixed cam  150  and the friction washer  170  further include a cam fixing surface  152  and a friction washer fixing surface  172  respectively to couple to a shaft fixing surface  212  of the shaft  210 . Therefore, when the display and the fixing bracket  130  are rotated, the fixed cam  150  and the friction washer  170  are constrained to avoid rotating the other component, e.g. the threaded nut  190 , so as to effectively avoid loosening the auto-locking mechanism  100 . 
     The auto-locking mechanism  100  further includes an auxiliary bracket  180  coupled to the shaft  210 . A bracket protrusion  182  of the auxiliary bracket  180  is further coupled to an opening  132  of the fixing bracket  130  to allow the auxiliary bracket  180  to horizontally move along the shaft  210  and provide an auxiliary force for the fixing bracket  130  to improve the rotating stability of the display while rotating the display. The auxiliary bracket  180  can increase a total strength and a frictional area for assisting the fixing bracket  130  to provide an adequate and stable torque for rotating the display. Between the threaded nut  190  and the auxiliary bracket  180 , an intermediate washer  174  is coupled and locked to the shaft  210  to avoid the auxiliary bracket  180  rotating and loosening the threaded nut  190  when the fixing bracket  130  is rotated. In addition, a lock nut can be adopted to further avoid loosening the threaded nut  190 . Because both sides of the auxiliary bracket  180  can be installed friction washers  170  to increase the friction force for rotating the fixing bracket  130  and the auxiliary bracket  180 , the torque for rotating the display is increased so as to effectively avoid an unexpected rotation of the display. 
       FIGS. 2A to 2C  illustrate partial enlarged views of the two-way auto-locking tablet PC hinge according to the present invention to explain the operation principle thereof. The rotational cam  240  and fixed cam  250  of the auto-locking mechanism are coupled to the shaft  310 . The rotational cam  240  is fixed on the fixing bracket (referring to  FIG. 1 ) and rotated on the shaft  310  when the fixing bracket is rotated. In addition, the fixed cam  250  utilizes the cam fixing surface  252  to fixedly couple to the shaft fixing surface  312  of the shaft  310 , and therefore the rotational cam  240  can rotate around the shaft  310  without driving the fixed cam  250  to rotate around the shaft  310 . 
     On the rotational cam  240  and the fixed cam  250 , a first positioner  260  and a second positioner  270  are formed. The first positioner  260  and the second positioner  270  are axially symmetrically disposed between the rotational cam  240  and the fixed cam  250  and around the shaft; that is, the first positioner  260  and the second positioner  270  are separated by about 180 degrees. The first positioner  260  is composed of a first protruding block  262  and a first concave  268 , and the second positioner  270  is composed of a second protruding block  276  and a second concave  278 . When the rotational cam  240  is rotated along a rotational direction  242 , the first protruding block  262  is forced out of the first concave  268  and the fixed cam  250  is pushed toward a direction  266 . When the fixed cam  250  is pushed along the direction  266 , the spring washer (referring to  FIG. 1 ) is deformed and therefore provides a force on the fixed cam  250  so as to restrain the first protruding block  262  from moving out of the first concave  268 . By adjusting a first inclined plane  264  and a stiffness value of the spring washer, a desired release torque can be determined to effectively prevent the first protruding block  262  from being unexpectedly moved out of the first concave  268  and the second protruding block  276  from being unexpectedly moved out of the second concave  278 . 
     Referring to  FIG. 2B , when a first inclined plane  264  and a second inclined plane  265  of the first protruding block  262  do not escape from the first concave  268 , the rotational cam  240  can automatically maintain a closed situation, referring to the situation illustrated in  FIG. 2A , due to the functionalities of the first inclined plane  264  and the spring washer. Therefore, when the display is closed on the base of the tablet PC, the display can stably stay in the closed position until a user opens the display from the base. 
     When the user desires to operate the tablet PC, the user only needs to rotate the upper cover of the tablet PC around the shaft  310 ; that is, to rotate the rotational cam  240  along the rotational direction  242 . The torque exerted by the user forces the first protruding block  262  out of the first concave  268  and the second protruding block  276  out of the second concave  278 . When top surfaces of the first protruding block  262  and the second protruding block  276  are moved to bottom surfaces  256  of the fixed cam  250 , lock surfaces  246  of the rotational cam  240  are separated from the bottom surface  256 . 
     Due to an increase of a gap  248 , the force on the fixed cam  250  is increased while the torque for rotating the rotational cam  240  is also increased until the first protruding block  262  and the second protruding block  276  touch the bottom surface  256 . When the first protruding block  262  and the second protruding block  276  contact the bottom surface  256  to provide a surface contact therebetween, a predetermined friction force is determined thereon. The torque for rotating the rotational cam  240  can maintain a predetermined torque because the gap  248  maintains a predetermined interval and the friction force maintains the predetermined friction force. The predetermined torque can effectively avoid an unintentional movement of the display and fix the display in the desired working angle. 
     When the rotational cam  240  is relatively rotated about the fixed cam  250  about 180 degrees, the first protruding block  262  is rotated to a position of the second concave  278 . Due to the functionality of the first inclined plane  264 , the first protruding block  262  of the rotational cam  240  slides into the second concave  278  along the first inclined plane  264  to engage with the second concave  278 . In the same manner, the second protruding block  276  automatically engages with the first concave  268 . Therefore, the display of the tablet PC is faced upwardly and steadily fixed in this position. In conjunction with the rotation of the central rotational frame (referring to  FIG. 1 ), the display of the tablet PC is laid on the base of the tablet PC so as to allow the user to conveniently handwrite on the display. 
     The two-way auto-locking tablet PC hinge according to the present invention couples the display to the base to enable the display to face downwardly and close on the base, or reversely rotate the display to face upwardly and lay on the base for handwriting. Since there is no hook protruding from the display, the appearance of the display of the tablet PC is smoother than that of conventional tablet PCs and the display can be easily opened and closed without an additional switch operation. When the display is almost parallel with the base, the first positioner and the second positioner of the auto-locking mechanism can automatically force the display parallel with the base, for example, an included angle about 0, 180 or 360 degrees therebetween. In addition, the display and the base can steadily stay in a position, for example, closed or a horizontally opened, until the user rotates the display. 
     The two-way auto-locking tablet PC hinge according to the present invention can quickly close the display of the tablet PC on the base thereof and conveniently reversely rotate the display to face up and close on the base. The two-way auto-locking tablet PC hinge according to the present invention has no hook protruding from the display, so as to beautify and smoothen the appearance of the display and allow the tablet PC to be operated conveniently by users. 
     As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. It is intended that various modifications and similar arrangements be included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.