A positioning hinge for providing pivotal positioning is disclosed. The positioning hinge comprises a pivotal member, a pivotal base, a first torsion spring and a friction device. The friction device includes a positioning element and a slide-friction member, which are kept in a resilient friction contact with each other by means of a resilient mechanism. This enables the LCD display to be opened due to the pivoting action of the pivotal base under the results of resilience and frictional positioning. It is appreciated that the above features advantageously result in an appropriate reduction in the opening speed of the LCD display while at the same time obtaining a steady frictional pivotal positioning, thereby prolonging the working life of the positioning hinge.

FIELD OF THE INVENTION  
         [0001]    The present invention relates to a positioning hinge, particularly to a positioning hinge for pivoting between a main unit and an LCD display of a portable computer or electronic dictionary, which can adjust the pivot orientation of the LCD display.  
         BACKGROUND OF INVENTION  
         [0002]    LCD displays of conventional portable computers are generally pivotally assembled on main units by a pair of hinges. U.S. Pat. No. 6,108,868 issued on 29 Aug. 2000 to Davys Lin discloses a positioning hinge having a cam block and a resilient friction member mounted on a pivotal base. The resilient friction member resiliently presses against the surface of the cam block to achieve the purpose of adjusting the orientation of the LCD display relative to the main unit. It is true that the '868 patent successfully achieves its predetermined purposes. However, because its resilient friction member is mounted on the pivotal member, the friction between the resilient friction member and the cam block has an undesirable, sudden change due to the complicated contour of the cam surface. That is, as the peripheral surface of the cam block diminishes in diameter, the friction force will be greatly reduced at the same time. This results in an unsmooth swinging of the LCD display. In details, the torsion spring constantly has a great torsion force during the swinging of the LCD display. When the LCD display suddenly stops due to the pivot positioning effect, the great torsion force in the torsion spring will shake the main unit and the LCD display due to the inertia in the display. In view of this defect, there is a need to provide an improved positioning hinge having a cushioning mechanism so as to obtain a relatively longer life.  
         SUMMARY OF THE INVENTION  
         [0003]    The object of the present invention is to provide an improved positioning hinge having the following advantages: (a) it provides a resilient swinging operation to the LCD display; (b) it allows a user to adjust the orientation of the LCD display when the display is resiliently swung to a predetermined viewing angle so as to adapt to ambient lighting; (c) it provides a smooth swinging operation to the LCD display so as to correct the positioning defects between the main unit and the display; and d) it provides a cushioning mechanism to the friction structure so as to reduce the wear between the hinge components.  
           [0004]    To achieve the above intended purposes, the positioning hinge according to the present invention essentially comprises a pivotal member, a pivotal base, a first torsion spring and a friction device.  
           [0005]    According to one embodiment of the present invention, the pivotal member is secured to a main unit and has a rotary shaft having a rotary axis. The pivotal base is secured to the LCD display and essentially includes a first support through which the rotary shaft passes so that the rotary shaft can pivot thereabout. The torsion spring has two ends which bias against the pivotal member and pivotal base, respectively, thereby providing a torsion force to allow the pivotal base to rotate with respect to the pivotal member so as to result in a relative pivotal movement between the display and the main unit. The positioning element formed with a friction surface is non-rotatably installed around the rotary shaft. The resilient compression member includes a slide-friction member and a resilient mechanism, wherein the resilient mechanism is provided between the pivotal base and the slide-friction member so that there is always a cushioning frictional contact between the slide-friction member and the positioning member.  
           [0006]    The above and other features and advantages of the present invention may be realized from the accompanying drawings and the following descriptions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is an exploded perspective view of a first embodiment of the present invention;  
         [0008]    [0008]FIG. 2 is an assembled perspective view of the embodiment of FIG. 1;  
         [0009]    FIGS.  3 A- 3 D are schematic views illustrating the positioning hinge being assembled to a portable computer;  
         [0010]    [0010]FIG. 4 is an exploded perspective view of a second embodiment of the present invention;  
         [0011]    [0011]FIG. 5 is an exploded perspective view of a third embodiment of the present invention;  
         [0012]    [0012]FIG. 6 is an assembled perspective view of the embodiment of FIG. 5;  
         [0013]    [0013]FIG. 7 is an exploded perspective view of a forth embodiment of the present invention; and  
         [0014]    [0014]FIG. 8 is an assembled perspective view of the embodiment of FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    [0015]FIGS. 1 and 2 illustrate a positioning hinge  1  according to a first embodiment of the present invention. The positioning hinge  1  generally comprises a pivotal member  10 , a pivotal base  20 , a first torsion spring  30 , a friction device  40  and a fastening member R.  
         [0016]    The pivotal member  10  comprises a mounting end  12  and a rotary shaft  14 . The mounting end  12  may further comprise holes R for mounting the pivotal member  14  to a main unit M (see FIGS.  3 A- 3 D). The rotary shaft  14  having a rotary axis preferably extends to a cylindrical shape.  
         [0017]    The pivotal base  20  comprises one or one pair of mounting part(s)  22  and at least one first support  24 . The mounting part  22  mounts the pivotal base  20  to an LCD display D (see FIGS.  3 A- 3 D). The support  24  is formed with a pivotal opening  26  through which the rotary shaft  14  passes. The pivotal base  20  is assembled to the pivotal member  10  through the pivotal opening  26  which allows the pivotal base  20  to rotate about the rotary axis of the pivotal member  10  between a first position (i.e., the LCD display being at a closed state) illustrated in FIG. 3A and a second position (i.e., the LCD display being at an open state) illustrated in FIGS.  3 B- 3 D.  
         [0018]    The first torsion spring  30  provided around the rotary shaft  14  has a first end  32  and a second end  34  biasing against the pivotal member  10  and the pivotal base  20 , respectively, to provide a torsion force to allow the pivotal base  20  to rotate about the pivotal member  10 . The couplings between the first end  32  and pivotal member  10  and between the second end  34  and the pivotal base  20  may be achieved by various structures. For example, it is preferable to provide a notch-type mounting ring  16  having a notch  18  on the pivotal member  10  and a tab  28  on the pivotal base  20 .  
         [0019]    The friction device  40  comprises a positioning element  50  and a resilient compression member  60 . The positioning element  50  comprises a friction surface  52  and a through hole  54 . The friction surface  52  generally shapes as a cam sidewall surrounding the rotary axis. The through hole  54  is configured to facilitate the positioning element  50  being non-rotatably assembled to the rotary shaft  14 .  
         [0020]    The resilient compression member  60  comprises a slide-friction member  62  and a resilient mechanism  64 . The slide-friction member  62  has a longitudinal axis supported by the pivotal base  20  and a contact surface  62   a  directly contacting the friction surface  52  of the positioning element  50 . The resilient mechanism  64  biases the slide-contact member  62  between the pivotal base  20  and the positioning element  50 . The resilient mechanism  64  preferably consists of at least one of disk springs  64   a  and slit-type disk springs  64   b.  Other appropriate resilient mechanism  64  includes arc-shaped resilient washers (not shown), wavy-shaped resilient washers (not shown), or a single spiral spring (not shown).  
         [0021]    After the members ( 10 , 20 , 30 , 40 ) are assembled to the pivotal member  10 , a ring-type fastening member R may be provided to secure these members in place so as to constitute the positioning hinge  1 . The ring-type fastening member R may be replaced by a nut-type fastening member N (see FIG. 4) or a collar-type fastening member C (see FIG. 5).  
         [0022]    FIGS.  3 A- 3 D are schematic views illustrating the operational states among the LCD display D, main unit M, positioning element  50  and resilient compression member  60  after the positioning hinge  1  is assembled to the computer. Before the LCD display D is swung open, the LCD display D is maintained at a closed position (FIG. 3A) adjacent to the main unit M by means of fastening means (such as fasteners); the first torsion spring  30  (not illustrated in FIGS.  3 A- 3 D) is under a torsion state, and the positioning element  50  has a smallest radius at this state in which the disk springs  64   a,b  are in a relaxed condition. As a user opens the LCD display D by pushing a release switch or by other methods, the torsion energy in the torsion spring  30  will urge the LCD display D to swing up automatically such that the pivotal base  20  rotates about the pivotal axis until the swinging action slows at a position where the positioning element  50  slightly increases in radius (FIG. 3B). At this state, the disk springs  64   a,b  withstand a pressure from the positioning element  50  due to the increased radius and the resilience of the disk springs  62   a,b  forces the contact surface  62   a  to keep in a closer contact with the friction surface  52 . FIG. 3C illustrates an example operating viewing angle (which is larger than 90 degrees) where the swinging action stops and the positioning element  50  has a greater radius than the radius shown at the state of FIG. 3B. Finally, the user may further adjust the LCD display D to attain an optimum viewing angle. In the illustrated examples of FIGS.  3 A- 3 D, disk springs  64   a,b  continue to resiliently pressure the slide-friction member  62 . It is preferable that the swinging operation from FIGS.  3 A- 3 C results in a smoothly-increased friction urging by the disk springs  64   a,b , while the swinging operation form of FIGS.  3 C- 3 D continues this resilient urging so as to maintain a greater friction force.  
         [0023]    [0023]FIG. 4 illustrates a second embodiment of a positioning hinge  100  according to the present invention, which comprises a pivotal member  110 , a pivotal base  120 , a torsion spring  130  and a friction device  140 .  
         [0024]    The pivotal member  110  comprises a mounting end  112  and a rotary shaft  114 . The pivotal base  120  comprises a mounting part  122  and a first support  124 . The first support  124  is formed with a pivotal opening  126 . The first torsion spring  130  is provided around the rotary shaft  114  and has a first end  132  and a second end  134  biasing against the pivotal member  110  and the pivotal base  120 , respectively. The friction device  140  comprises a positioning element  150  and a resilient compression member  160 . The resilient compression member  160  comprises a slide-friction member  162  and a resilient mechanism  164 . The slide-friction member  162  has a longitudinal axis supported by the pivotal base  120 . The resilient mechanism  164  biases the slide-contact member  162  between the pivotal base  120  and the positioning element  150 .  
         [0025]    [0025]FIGS. 5 and 6 illustrate a third embodiment of a positioning hinge  200  according to the present invention. The positioning hinge  200  comprises a pivotal member  210 , a pivotal base  220 , a first torsion spring  230 , a friction device  240  including a positioning element  250  and resilient compression member  260 , and a fastening member C. The pivotal member  210  comprises a mounting end  212 , a rotary shaft  214 , and a notch-type mounting ring. The pivotal base  220  comprises at least one mounting part  222  and at least one first support  224 . The first torsion spring  230  has a first end  232  and a second end  234  biasing against a notch  218  of notch-type mounting ring  216  and the pivotal base  220 , respectively. A sleeve S may be fitted into the first torsion spring to avoid the leakage of the lubricant oil. The resilient compression member  260  comprises a slide-friction member  262  and a resilient mechanism  264 . The slide-friction member  262  has a longitudinal axis supported by the pivotal base  220 . The resilient mechanism  264  biases the slide-contact member  262  between the pivotal base  220  and the positioning element  250 . When the pivotal base  220  rotates, the slide-friction member  262  will slide on the friction surface  252  of the positioning element  250 , thereby traveling along its longitudinal axis depending on the ups or downs of the friction surface  252  under the biasing of the resilient mechanism  264 . The operation of positioning hinge  200  is identical to that shown in FIGS.  3 A- 3 D.  
         [0026]    The slide-friction member  262  preferably further comprises a tuning device ( 266 , 268 ) that couples with the pivotal base  220  to limit the axial movement of the slide-friction member  262 . The tuning device ( 266 , 268 ) allows a user to manually adjust the tightness degree of contact between the slide-friction member  262  and the positioning element  250 . The tuning device preferably consists of a threaded portion  266  formed on the slide-friction member  262  and a nut  268  mating with the threaded portion  266 .  
         [0027]    As the invention has been particularly described with respect to preferred embodiments thereof, persons skilled in the art will understand that the above and other changes in form and detail may be made without departing from the scope and spirit of the invention.