Patent Publication Number: US-10306977-B2

Title: Height adjustable desk

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a desk and more specifically pertains to a height adjustable desk. 
     Height adjustable desks are widely available in the marketplace. To reduce the force required by users to lift up the desktop when adjusting the height of the desk, hydraulic cylinders are commonly used. However, such height adjustable desks have more complicated structure, and are therefore less economical to manufacture. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the aforesaid disadvantages now present in the prior art, the object of the present invention is to provide a height adjustable desk which are simple in structure, easy to manufacture and assemble and low in costs. The present invention is capable of reducing the force required by the user to lift up the desktop, and also provides a convenient means for user to adjust the desktop  1  to various heights. 
     To attain this, the height adjustable desk of the present invention comprises a desktop which engages with a pair of base supports by a pair of X-shaped frames and is adjustable between a fully raised position and a fully lowered position. The pair of X-shaped frames each comprises a first arm and a second arm; the first arm has a first top end and a first bottom end, wherein the first top end is pivotally connected to a top front pivot point fixedly connected to the desktop, and the first bottom end is pivotally connected to a bottom rear pivot point movably connected to the corresponding base support; the second arm has a second top end and a second bottom end, wherein the second top end is pivotally connected to a top rear pivot point movably connected to the desktop, and the second bottom end is pivotally connected to a bottom front pivot point fixedly connected to the corresponding base support. The pair of base supports each comprises a first biasing means and a second biasing means. The first biasing means has a first end which engages the second bottom end of the corresponding second arm and a second end which engages a front end of the corresponding base support; the first biasing means is configured to bias the corresponding second arm upwards to move the desktop towards the fully raised position. The second biasing means has a first end which engages the first bottom end of the corresponding first arm and a second end which engages the corresponding base support; the second biasing means is configured to bias the corresponding first arm upwards to move the desktop towards the fully raised position. 
     In one embodiment, each of the first biasing means is in form of a torsion spring with a first leg engaging the second bottom end of the corresponding second arm and a second leg abutting against an inner side of the corresponding base support. 
     In one embodiment, each of the second biasing means is in form of a coil spring with the second end thereof engaging the corresponding base support at a position near the front end of the corresponding base support. In other embodiments, each of the second biasing means may also be in form of a gas spring with the second end thereof engaging the corresponding base support at a position near a rear end of the corresponding base support. 
     In one embodiment, a first lower bracket is provided at a lower end of each of the first arms and slides along a lower guide rail extending along the corresponding base support; each of the first lower brackets has an upper portion and a lower portion; the first bottom end of the corresponding first arm is pivotally connected to the corresponding upper portion at the corresponding bottom rear pivot point; the lower portion is provided with a protrusion by which the first end of the corresponding second biasing means engages the first bottom end of the corresponding first arm. 
     In one embodiment, a pair of height adjustment means is provided on an underside of the desktop, each of which comprises a handle, a guiding member, a connecting piece and a biasing member. The handle is rotatable between an upward position and a downward position. The guiding member is provided with a plurality of slots and fixedly connected to the corresponding top rear pivot point and is movable in relation to the desktop along an upper guide rail as the desktop is moved between the fully raised position and the fully lowered position. The connecting piece is connected to the handle via a linkage mechanism so that rotation of the handle to the upward position moves the connecting piece to an unlocking position and rotation of the handle to the downward position moves the connecting piece to a locking position; the connecting piece is provided with a laterally extended tab portion which is configured to fit into any of the plurality of slots of the guide member in the locking position so as to fix the position of the desktop in relation to the pair of base supports. The biasing member biases the connecting piece towards the locking position. 
     In one embodiment, each of the linkage mechanism comprises a rotating rod, a first linkage member and a second linkage arm. The rotating rod has a first end rotatably connected to the corresponding handle. The first linkage member has a first end which is rotatable by a second end of the rotating rod. The second linkage arm has a first end which is pivotably connected to a second end of the first linkage member and a second end which is pivotably connected to the corresponding connecting piece. Simultaneous rotation of the handles to the upward position drives rotation of the first linkage members around the rotating rods along a first direction and thereby rotates the first ends of the second linkage arms from a vertical position to a horizontal position; the second ends of the second linkage arms are thereby driven to move downwards and causes the connecting pieces to overcome biasing force exerted by the biasing members to move downward to the unlocking position 
     In one embodiment, each of the biasing members is in form of a spring with a first end abutting against the underside of the desktop and a second end abutting against the corresponding connecting member. 
     In one embodiment, each of the top front pivot points is fixedly connected to the desktop via a first upper bracket; each of the bottom rear pivot points is movably connected to the corresponding base support via the first lower bracket; each of the top rear pivot points is movably connected to the desktop via a second upper bracket; each of the bottom front pivot points is fixedly connected to the corresponding base support via a second lower bracket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of the present invention. 
         FIG. 2  is another perspective view of the preferred embodiment as shown in  FIG. 1 . 
         FIG. 3  is a partial perspective view of one of the pair of base supports of the preferred embodiment as shown in  FIG. 1  with some parts removed for better illustration of the first biasing means and the second biasing means. 
         FIG. 4  is another partial perspective view of one of the pair of base supports of the preferred embodiment as shown in  FIG. 1  with some parts removed for better illustration of the first biasing means and the second biasing means. 
         FIG. 5  is a partial perspective view illustrating one of the pair of height adjustment means of the preferred embodiment as shown in  FIG. 1 . 
         FIG. 6  is another partial perspective view illustrating one of the pair of height adjustment means of the preferred embodiment as shown in  FIG. 1 . 
         FIG. 7  is another partial perspective view illustrating one of the pair of height adjustment means of the preferred embodiment as shown in  FIG. 1  with some parts removed for better illustration. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is further described in detail with the following embodiment and the accompanying drawings. 
     As illustrated in  FIGS. 1-7 , a preferred embodiment of the height adjustable desk comprises a desktop  1 , a pair of base supports  2  and a pair of X-shaped frames  3 . The pair of X-shaped frames  3  engages the desktop  1  with the pair of base supports  2 . The desktop  1  is adjustable between a fully raised position and a fully lowered position. 
     The pair of X-shaped frames  3  each has a first arm  31  and a second arm  32 . Each of the first arms  31  has a first top end  311  and a first bottom end  312 , wherein the first top end  311  is pivotally connected to a top front pivot point  313  fixedly connected to the desktop  1  via a first upper bracket  315 , and the first bottom end  312  is pivotally connected to a bottom rear pivot point  314  movably connected to the corresponding base support  2  via a first lower bracket  316 . Each of the second arms  32  has a second top end  321  and a second bottom end  322 , wherein the second top end  321  is pivotally connected to a top rear pivot point  323  movably connected to the desktop  1  via a second upper bracket  325 , and the second bottom end  322  is pivotally connected to a bottom front pivot point  324  fixedly connected to the corresponding base support  2  via a second lower bracket  326 . 
     Each of the pair of base supports  2  has a first biasing means  4  and a second biasing means  5 . In this embodiment, the first biasing means  4  is in form of a torsion spring with a first leg and a second leg which respectively serve as a first end  41  and a second end  42  of the first biasing means  4 , wherein the first end  41  engages the second bottom end  322  of the corresponding second arm  32  and the second end  42  engages a front end  21  of the corresponding base support  2  by abutting against an inner side of the first lower bracket  326 ; the first biasing means  4  is configured to bias the corresponding second arm  32  upwards to move the desktop  1  towards the fully raised position. In this embodiment, the second biasing means  5  is in form of a coil spring having a first end  51  which engages the first bottom end  312  of the corresponding first arm  31  via the corresponding first lower bracket  316  and a second end  52  which engages the corresponding base support  2  at a position near the front end  21  of the corresponding base support  2 ; the second biasing means  5  is configured to bias the corresponding first arm  31  upwards to move the desktop  1  towards the fully raised position. 
     Each of the first lower brackets  316  provided at a lower end of each of the first arms  31  slides along a lower guide rail  7  extending along the corresponding base support  2 . Each of the first lower brackets  316  has an upper portion  3161  and a lower portion  3162 ; the first bottom end  312  of the corresponding first arm  31  is pivotally connected to the corresponding upper portion  3161  at the corresponding bottom rear pivot point  314 ; the lower portion  3162  is provided with a protrusion  3163  by which the first end  51  of the corresponding second biasing means  5  engages the first bottom end  312  of the corresponding first arm  31 . 
     During operation, when the user exerts a downward force to push the desktop  1  downward from the fully raised position to the fully lowered position, the first ends  41  of the first biasing means  4  are compressed, and the first lower brackets  316  are forced to slide rearward along the lower guide rails  7  and thus forces the second biasing means  5  to extend and enter a stressed state. When the user lifts the desktop  1  upwards, the first ends  41  of the first biasing means  4  are urged to return to their uncompressed state, thus providing an uplifting force which facilitates uplifting of the desktop  1 ; furthermore, the second biasing means  5  are also urged to contract and return to their relaxed state, thus providing a pull force to pull the first lower brackets  316  forward, thus facilitating uplifting of the desktop  1 . The actions of the first biasing means  4  and the second biasing means  5  help to reduce the force required by the user to lift up the desktop  1 . 
     An underside  11  of the desktop  1  is provided with a pair of height adjustment means  8 . The pair of height adjustment means  8  each comprises a handle  81 , a connecting piece  82 , a linkage mechanism  83 , a biasing member  84  and a guiding member  85 . Each of the handles  81  is rotatable between an upward position and a downward position. Each of the guiding members  85  is provided with a plurality of slots  851  and is fixedly connected to the corresponding top rear pivot point  323  via the corresponding second upper bracket  325 , and is movable in relation to the desktop  1  along an upper guide rail  9  fixedly provided at the underside of the desktop  1  as the desktop  1  is moved between the fully raised position and the fully lowered position. Each of the connecting pieces  82  is connected to the corresponding handle  81  via a linkage mechanism  83  so that rotation of the corresponding handle  81  to the upward position moves the connecting piece  82  to an unlocking position and rotation of the corresponding handle  81  to the downward position moves the connecting piece  82  to a locking position. Each of the connecting pieces  82  is provided with a laterally extended tab portion  821  which is configured to fit into any of the plurality of slots  851  of the corresponding guiding member  85  in the locking position so as to fix the position of the desktop  1  in relation to the pair of base supports  2 . Each of the biasing members  84  biases the corresponding connecting piece  82  towards the locking position. In the present embodiment, each of the biasing members  84  is in form of a spring with a first end  841  abutting against the underside  11  of the desktop  1  and a second end  842  abutting against the corresponding connecting member  82 . 
     Each of the linkage mechanisms  83  comprises a rotating rod  831 , a first linkage member  832  and a second linkage arm  833 . Each of the rotating rods  831  has a first end  8311  rotatably connected to the corresponding handle  81 . Each of the first linkage members  832  has a first end  8321  which is rotatable by a second end  8312  of the corresponding rotating rod  831 . Each of the second linkage arms  833  has a first end  8331  which is pivotably connected to a second end  8322  of the corresponding first linkage member  832  and a second end  8332  which is pivotably connected to the corresponding connecting piece  82 . 
     During operation, when the user wishes to adjust the position of the desktop  1 , the user simultaneously rotates the two handles  81  to the upward position, thereby drives rotation of the first linkage members  831  around the rotating rods  832  along a first direction (as indicated by the arrow A in  FIG. 7 ) to rotate the first ends  8331  of the second linkage arms  833  from a vertical position (as shown in  FIG. 7 ) to a horizontal position; the second ends  8332  of the second linkage arms  833  are thereby driven to move downwards and causes the connecting pieces  82  to overcome biasing force exerted by the biasing members  84  to move downward to the unlocking position. The tab portions  821  of the connecting pieces  82  thus no longer snap into any of the slots  851  of the guiding members  85 , and the guiding members  85  are freely movable along the upper guide rails  9  to move the desktop  1  between the fully raised position and the fully lowered position. The plurality of slots  851  provided in each of the guiding members  85  allows the user to fix the desktop  1  at a corresponding number of positions between the fully raised position and the fully lowered position. 
     The present embodiment further comprises a keyboard tray  10  which is fixedly engaged with the desktop  1  so that adjusting the height of the desktop  1  also results in the same adjustment of the height of the keyboard tray  10 . An reinforcing bar  101  fixedly connects the first arms  31  of the pair of X-shaped frames  3  to improve rigidity of the desk. Covers  102  are provided at the pair of base supports  2  to conceal the first biasing means  4  and the second biasing means  5 . The aforementioned structures are obvious to those skilled in the art and are therefore not detailed herein. 
     The pair of X-shaped frames  3  and the pair of height adjustment means  8  of the present invention are simple in structure, easy to manufacture and assemble and low in costs. The pair of X-shaped frames  3  reduces the force required by the user to lift up the desktop  1 . The pair of height adjustment means  8  provides a convenient means for user to adjust the desktop  1  to various heights. 
     The above embodiment is a preferred embodiment of the present invention. The present invention is capable of other embodiments and is not limited by the above embodiment. Any other variation, decoration, substitution, combination or simplification, whether in substance or in principle, not deviated from the spirit of the present invention, is replacement or substitution of equivalent effect and falls within the scope of protection of the present invention.