Abstract:
A self-locking keyboard bracket is disclosed to include a four-bar linkage, formed of a base frame, a connecting frame, a coupling frame, and a braking mechanism, a supporting frame fastened pivotally with the coupling frame, and an angle adjustment control unit for locking the supporting frame to the coupling frame at the desired angle by means of the operation of a locking bar with a cam. The braking mechanism uses a beveled block to mach with a beveled guide block to further control friction resistance between the base frame and the connecting frame, thereby achieving self-locking of the keyboard bracket.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a keyboard bracket and more particularly, to a self-locking keyboard bracket, allowing the user to conveniently adjust the elevation and angle of the supporting frame.  
         [0003]     2. Description of Related Art  
         [0004]     Following fast development of information industry, computer is becoming a popular equipment used in office as well as at home for paper working to substitute conventional writing apparatus. In consequence, computer peripheral apparatus such as keyboard and mouse have come intimate partners of a computer user. However, regular computer peripheral apparatus occupy much installation gap space. It is difficult to find a gap space on the limited area of the top of a table for receiving a computer peripheral apparatus. It is also inconvenient to operate a computer peripheral apparatus on the top of a table. When installed a computer peripheral apparatus, the elevation and angle of the computer peripheral apparatus may not fit the user perfectly, and the user may ache all over within a short period of time in operating the computer peripheral apparatus. In order to eliminate this problem, adjustable bracket means may be used to support a computer peripheral apparatus on a table for convenient use.  
         [0005]     FIGS.  1 A˜ 1 C show a conventional keyboard bracket for supporting a keyboard on a table. The structure of keyboard bracket comprises a holder base  10 , a connecting frame  20 , a limiter  25 , an adjustment control set  30 , a first torsional spring  24 , a keyboard support  26 , a second torsional spring  28 , and a locking mechanism  36 . The holder base  10  is a substantially          -shaped solid frame. The connecting frame  20  is a substantially          -shaped frame bar having a first pivot hole  21  at one end, a second pivot hole  23  at the other end, and a smoothly arched sliding slot  22  adjacent to the first pivot hole  21 . The first pivot hole  21  and the smoothly arched sliding slot  22  of the connecting frame  20  are respectively pivoted to the holder base  10  by a first pivot pin  11  and a second pivot pin  12 . The limiter  25  is a flat rod member longitudinally suspended inside the connecting frame  20 , having a pivot hole  252  disposed at one end and coupled to the second pivot pin  12  and a longitudinal sliding slot  253  disposed at the other end and coupled to the second pivot hole  23  of the connecting frame  20 . The adjustment control set  30  comprises a pivot pin  31  pivotally fastened to a pivot hole  261  in one end of the keyboard support  26  and the second pivot hole  23  of the connecting frame  20  and the longitudinal sliding slot  253  of the limiter  25 , a traction plate  32  coupled between the pivot pin  31  and the keyboard support  26 , a barrel  34  sleeved onto the pivot pin  31  and stopped between the locking mechanism  36  and the traction plate  32 , a spring member  33  mounted on the pivot pin  31  and stopped between the traction plate  32  and one end of the barrel  34 , a cushion  37  mounted on the pivot pin  31  and supported between the traction plate  32  and the spring member  33 , and washers  35  mounted on the pivot pin  31  at the two distal ends of the barrel  34 . The first torsional spring  24  is mounted on the first pivot pin  11  and connected between the holder base  10  and the connecting frame  20 . The keyboard support  26  is shaped like a channel bar for supporting a keyboard or computer peripheral apparatus. The second torsional spring  28  is mounted on a pin in the keyboard support  26  and connected between the connecting frame  20  and the keyboard support  26 . The locking mechanism  36  comprises an eccentric block  36  coupled to the pivot pin  31 , the eccentric block  36  being a parallelogram having a long side  362 , a short side  364 , and an arched opening  363 , a locating block  365  extended from one side of the eccentric block  36 , and a handle  367  fastened to the locating block  365  for turning the eccentric block  36 . By means of operating the handle  367  to turn the eccentric block  36  relative to the keyboard support  26 , and the limiter  25  and the traction plate  32  can be loosened, enabling the keyboard support  26  to be adjusted to the desired elevation or angle.  
         [0006]     Referring to  FIGS. 2A and 2B , when wishing to adjust the elevation or angle of the keyboard support  26 , operate the handle  367  to move the eccentric block  361 , causing the position of the arched opening  363  of the eccentric block  361  to be changed through 90° angle relative to the pivot pin  31 . At this time, the long side  362  of the eccentric block  361  is moved into contact with one washer  35  against the barrel  34 , and the short side  364  of the eccentric block  361  is moved to the axial direction of the pivot pin  31 , and therefore the eccentric block  361  occupies less axial gap space around the pivot pin  31 , allowing the spring member  33  to push the barrel  34  outwards. Upon outward displacement of the barrel  34  along the pivot pin  31 , the limiter  25 , the cushion  37  and the traction plate  32  are loosened.  
         [0007]     Referring to  FIGS. 3A and 3B , when wishing to adjust the angle of the keyboard support  26 , operate the handle  367  to loosen the keyboard bracket as stated above, and then turn the keyboard support  26  about the pivot pin  31  relative to the connecting frame  20  to the desired angle, and then turn the handle  367  in the reversed direction to force the short side  364  of the eccentric block  361  against the washers  35 , the barrel  34  and the spring member  33 , and at the same time the long side  362 of the eccentric block  361  is moved to the axial direction of the pivot pin  31  to occupy more axial gap space around the pivot pin  31 , and therefore the barrel  34  is forced into the inside of the keyboard support  34  to compress spring member  33  against the cushion  37 , the limiter  25  and the traction plate  32 , and therefore the keyboard support  26  is locked to the connecting frame  20 .  
         [0008]     When wishing to adjust the elevation of the keyboard support  26 , operate the handle  367  to loosen the keyboard bracket, and then turn the connecting frame  20  with the keyboard support  26  about the first pivot pin  11 . Because of the keyboard support  26  is coupled to the longitudinal sliding slot  253  of the limiter  25  by the pivot pin  31 , the keyboard support  26  is maintained in horizontal when turning the connecting frame  20  about the first pivot pin  11  relative to the holder base  10 . When adjusted to the desired elevation, the handle  367  is turned in the reversed direction to lock the limiter  25  and the traction plate  32  again.  
         [0009]     This structure of keyboard bracket is functional, however it still has numerous drawbacks as outlined hereinafter. 
        1. Simply using one adjustment control set to control the elevation and angle of the keyboard bracket does not allow the user to accurately and rapidly adjust the keyboard bracket to the desired position.     2. Upon each elevation or angle adjustment, the eccentric block is forced to rub against the respective washer, therefore the eccentric block starts to wear quickly with the use of the keyboard bracket. When the eccentric block starts to wear, the load carrying power of the keyboard bracket is relatively reduced.     3. The complicated adjustment control set greatly complicates the manufacturing process and increases the manufacturing cost.        
 
       SUMMARY OF THE INVENTION  
       [0013]     The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a self-locking keyboard bracket, which eliminates the aforesaid drawbacks. According to one aspect of the present invention, the self-locking keyboard bracket uses a four-bar linkage to support a supporting frame for carrying a keyboard, which four-bar linkage is formed of a base frame, a connecting frame, a coupling frame and a braking mechanism. The braking mechanism uses a beveled block to mach with a beveled guide block to further control friction resistance between the base frame and the connecting frame, thereby achieving self-locking of the keyboard bracket. According to another aspect of the present invention, the self-locking keyboard bracket further comprises an angle adjustment control unit, which is controlled by a locking lever with a cam to lock the supporting frame to the coupling frame or unlock the supporting frame from the coupling frame, for enabling the supporting frame to be adjusted to the desired angle. According to still another aspect of the present invention, packing members and washers are used in the braking mechanism to increase friction resistance between parts upon self-locking of the keyboard bracket, thereby increasing the load carrying power of the keyboard bracket. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1A  is an exploded view of a keyboard bracket according to the prior art.  
         [0015]      FIG. 1B  is a perspective assembly view of the keyboard bracket according to the prior art.  
         [0016]      FIG. 1C  is a top view in section of the keyboard bracket according to the prior art.  
         [0017]      FIG. 2A  is an enlarged view of a part of the keyboard bracket according to the prior art.  
         [0018]      FIG. 2B  is a top view of  FIG. 2A .  
         [0019]      FIG. 3A  is a schematic side view showing the supporting frame of the keyboard bracket adjusted between a first elevation and a second elevation according to the prior art.  
         [0020]      FIG. 3B  is a schematic side view showing the supporting frame of the keyboard bracket adjusted between a first angle and a second angle according to the prior art.  
         [0021]      FIG. 4A  is an exploded view of a self-locking keyboard bracket according to the present invention.  
         [0022]      FIG. 4B  is a perspective assembly view of the self-locking keyboard bracket according to the present invention.  
         [0023]      FIG. 5A  is a side view in an enlarged scale of a part of the present invention, showing the locking status of the braking mechanism in the connecting frame.  
         [0024]      FIG. 5B  is similar to  FIG. 5A  but showing the unlocking status of the braking mechanism.  
         [0025]      FIG. 5C  is bottom view in an enlarged scale of the present invention, showing the locking status of the keyboard bracket.  
         [0026]      FIG. 5D  is similar to  FIG. 5C  but showing the unlocking status of the keyboard bracket/  
         [0027]      FIG. 6A  is a side view in an enlarged scale of a part of the present invention, showing the supporting frame adjusted to a first elevation.  
         [0028]      FIG. 6B  is similar to  FIG. 6A  but showing the supporting frame adjusted to a second elevation.  
         [0029]      FIG. 7  is top views in an enlarged scale of a part of the present invention, showing the locking status and unlocking status of the angle adjustment control unit.  
         [0030]      FIG. 8A  is a side view in an enlarged scale of a part of the present invention, showing the supporting frame adjusted to a first angle.  
         [0031]      FIG. 8B  is similar to  FIG. 8A  but showing the supporting frame adjusted to a second angle. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]     Referring to  FIGS. 4A and 4B , a self-locking keyboard bracket in accordance with the present invention is shown comprised of a base frame  40 , a track  45 , a slide  47 , a connecting frame  50 , a coupling frame  60 , a supporting frame  70 , a braking mechanism  80 , and an angle adjustment control unit  75 .  
         [0033]     The base frame  40  comprises at least one, for example, two downwardly extended side wings  41 , a first axle hole  412  horizontally extended through each side wing  41 , a second axle hole  414  horizontally extended through each side wing  41  below the first axle hole  412 , and a third axle hole  43  vertically extended through the top wall thereof.  
         [0034]     The track  45  comprises two parallel sliding grooves  451 .  
         [0035]     The slide  47  comprises two side flanges  471  longitudinally slidably inserted into the sliding grooves  451  for allowing relative movement between the slide  47  and the track  45 , and a vertically extended axle hole  473  connected to the third axle hole  43  of the base frame  40  by a pivot pin  433  for allowing relative rotation in horizontal direction between the slide  47  and the base frame  40 .  
         [0036]     The connecting frame  50  comprises at least one, for example, two downwardly extended side wings  51 , a first axle hole  511  transversely extended through each side wing  51  near one end, a second axle hole  512  transversely extended through each side wing  51  near the other end, a third axle hole  515  transversely extended through each side wing  51  on the middle, and a smoothly arched sliding slot  514  cut through each side wing  51  adjacent to the second axle hole  512 .  
         [0037]     The coupling frame  60  comprises at least one, for example, two downwardly extended side wings  61 , and three axle holes, namely, the first axle hole  611 , the second axle hole  617  and the third axle hole  613  transversely extended through each side wing  61 .  
         [0038]     The supporting frame  70  comprises at least one, for example, two downwardly extended side wings  71 , an axle hole  711  and a smoothly arched sliding slot  717  cut through each side wing  71 .  
         [0039]     The braking mechanism  80  is comprised of at least one, for example, two links  81 , two beveled guide blocks  83 , a first sleeve  851 , a second sleeve  853 , packing members  87 , and washers  89 . The links  81  are arranged in parallel, each having a first end, which has a transversely extended axle hole  813 , and a second end, which is fixedly provided with a beveled block  815  and has an axle hole  814  transversely extended through the beveled block  815 . The beveled guide blocks  83  each have a coupling groove  835  disposed at one side and coupled to the beveled block  815  of one link  81 , and an axle hole  834  transversely extended through the coupling groove  835 . The packing members  87  each have a smoothly arched sliding slot  874  at one end and a transversely extended axle hole  875  at the other end. The washers  89  each have a center axle hole  894 .  
         [0040]     The angle adjustment control unit  75  is comprised of a locking lever  751 , a hollow stop block  753 , a barrel  755 , an axle  757 , and a fastening device  758 . The locking lever  751  has a cam  752  fixedly disposed one end and pivotally connected to one end of the axle  757  by a pivot  754 . The axle  757  has the other end provided with an outer thread  756 . The fastening device  758  according to this embodiment is a cap nut threaded onto the outer thread  756  of the axle  757 . The axle  757  is inserted through the hollow stop block  753  and the barrel  755  and then the sliding slots  717  in the downward side wings  71  of the supporting frame  70  and the second axle holes  617  in the downward side wings  61  of the coupling frame  60  and then screwed up with the fastening device  758 , thereby allowing relative movement between the supporting frame  70  and the coupling frame  60 .  
         [0041]     Further, a first pivot pin  91  is mounted in the axle holes  711  in the downward side wings  71  of the supporting frame  70 , the first axle holes  611  in the downward side wings  61  of the coupling frame  60  and the first axle holes  511  in the downward side wings  51  of the connecting frame  50  to pivotally secure the supporting frame  70 , the coupling frame  60  and the connecting frame  50  together. A second pivot pin  92  is mounted in the first axle holes  412  in the downward side wings  41  of the base frame  40 , and the second axle holes  512  in the downward side wings  51  of the connecting frame  50 . A spring member  52  is sleeved onto the second pivot pin  92 , having a protruding middle part  524  retained to the base frame  40  and two distal ends  525  retained to the connecting frame  50 . The spring member  52  returns the connecting frame  50  to its former position after the connecting frame  50  being turned relative to the base frame  40 . A third pivot  93  is mounted in the third axle holes  613  in the downward side wings  61  of the coupling frame  60  and the axle hole  813  in the first end of each link  81  of the braking mechanism  80  and the second sleeve  853  between the links  81  to pivotally couple the braking mechanism  80  to the coupling frame  60 . Due to the effect of the second sleeve  853 , relative turning action between the braking mechanism  80  and the coupling frame  60  is smoothened. A fourth pivot pin  94  is mounted in the second axle holes  414  in the downward side wings  41  of the base frame  40 , the smoothly arched sliding slots  514  in the downward side wings  51  of the connecting frame  50 , the axle holes  834  of the beveled guide blocks  83 , the axle hole  814  in the second end of each link  81 , the sliding slots  874  of the packing members  87 , and the first sleeve  851  to pivotally secure the braking mechanism  80  to the base frame  40 , allowing relative swivel motion between the braking mechanism  80  and the base frame  40 . Thus, the base frame  40 , the connecting frame  50 , the braking mechanism  80 , the coupling frame  60  and the supporting frame  70  form a four-bar linkage keyboard bracket. Further, a fifth pivot pin  95  is mounted in the third axle holes  515  in the downward side wings  51  of the connecting frame  50  and the axle holes  875  of the packing members  87  to hold the packing members  87  between the connecting frame  50  and the braking mechanism  80 .  
         [0042]     Referring to  FIGS. 5A-5D , when turning the coupling frame  60  about the first pivot pin  91  relative to the connecting frame  50 , the third pivot pin  93  is forced to move the links  81 , however, because the diameter of the second axle holes  814  of the links  81  (the axle holes in the second ends of the links), the fourth pivot pin  94  which is constrained by the second axle holes  414  of the base frame  40  is forced to move relative to the links  81  at this time. Therefore, the beveled blocks  815  of the links  81  are forced to move along the grooves  835  of the beveled guide blocks  83  to increase or reduce the gap in between the members coupled to the fourth pivot pin  94 . However, because the gap between the two downward side wings  41  of the base frame  40  is fixed, reducing/increasing the gap between each two adjacent members that are coupled to the fourth pivot pin  94  produces a resisting force or releases the force, thereby locking/unlocking the keyboard bracket. Further, the fourth pivot pin  94  is inserted through the axle holes  894  of the washers  89  to support the washers  89  between the links  81  and the packing members  87  and between the packing members  87  and the first sleeve  851  to increase friction resisting during locking of the keyboard bracket. Because the packing members  87  are provided between the connecting frame  50  and the braking mechanism  80 , turning the connecting frame  50  about the second pivot pin  92  relative to the base frame  40  causes the fifth pivot pin  95  to drag the packing members  87 , and therefore the fourth pivot pin  94  is moved along the smoothly arched sliding slots  874  of the packing members  87  relative to the packing members  87 . Thus, it is necessary to turn the coupling frame  60  within a limited small angle when locking/unlocking the keyboard bracket. When locked, the keyboard bracket supports a heady keyboard and the pressure from the user&#39;s wrist stably, enabling the user to operate the keyboard comfortably.  
         [0043]     Referring to  FIGS. 6A and 6B , when turning the coupling frame  60  to unlock the keyboard bracket, at this time the connecting frame  50  is turned about the second pivot pin  92  relative to the base frame  40 , and the fourth pivot pin  94 , due to the constraint of the second axle holes  414  of the base frame  40 , is forced to move along the smoothly arched sliding slots  514  of the connecting frame  50 . During this turning action, the braking mechanism  80 , the coupling frame  60  and the supporting frame  70  are moved with the connecting frame  50 . After having turned the supporting frame  70  to a proper elevation, stop turning the coupling frame  60 , allowing the coupling frame  60  to be forced downwards by the load at the keyboard bracket, and therefore the keyboard bracket is locked at the desired elevation.  
         [0044]     Referring to  FIG. 7 , as indicated above, the cam  752  of the locking lever  751  is pivoted to one end of the axle  757  with the pivot  754 , therefore the locking lever  751  can be turned relative to the axle  757  between two positions, namely, the locking position and the unlocking position. When turning the locking lever  751  to the locking position, the&amp; cam  752  forces the stop block  753  against the barrel  755  to move the supporting frame  70  and the coupling frame  60  leftwards, and at the same time the locking lever  751  pulls the axle  757  rightwards. However, because the axle  757  is inserted through the hollow stop block  753  and the barrel  755  and then the sliding slots  717  in the downward side wings  71  of the supporting frame  70  and the second axle holes  617  in the downward side wings  61  of the coupling frame  60  and then screwed up with the fastening device  758 , the aforesaid rightward traction force causes the fastening device  758  to act against the supporting frame  70  and the coupling frame  60  in contra to the leftward pressure from the barrel  755 , thereby holding down the supporting frame  70  and the coupling frame  60 . On the contrary, when turning the locking lever  751  in the reversed direction from the locking position to the unlocking position, the supporting frame  70  and the coupling frame  60  are loosened.  
         [0045]     Referring to  FIGS. 8A and 8B , when the supporting frame  70  and the coupling frame  60  are in the loosened status (unlocking position), the supporting frame  70  is turnable about the first pivot pin  91  relative to the coupling frame  60 . When turning the supporting frame  70  about the first pivot pin  91  relative to the coupling frame  60  at this time, the axle  757  is constrained by the second axle holes  617  of the coupling frame  60  and forced to move along the smoothly arched sliding slots  717  of the supporting frame  70 . After the supporting frame  70  has been adjusted to the desired angle, turn the locking lever  751  to the locking position to lock the supporting frame  70  to the coupling frame  60 .  
         [0046]     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.