Patent Publication Number: US-2009224592-A1

Title: Chair Backrest that is Assembled and Disassembled Easily and Quickly Without Needing Aid of a Hand Tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a backrest and, more particularly, to a backrest for a chair. 
     2. Description of the Related Art 
     A conventional chair backrest in accordance with the prior art shown in  FIGS. 6 and 7  comprises a support bracket  1  and a backrest cushion  2 . The support bracket  1  has two parallel support bars  11  each provided with a mounting groove  12  and a mounting hole  13 . The backrest cushion  2  has two parallel connecting portions  21  each provided with a snapping groove  22  and a mounting bore  23 . In assembly, each of the connecting portions  21  of the backrest cushion  2  is inserted into the mounting groove  12  of the respective support bar  11  of the support bracket  1 , and the conventional chair backrest further comprises two locking screw  20  each extending through the mounting hole  13  of the respective support bar  11  of the support bracket  1  and the mounting bore  23  of the respective connecting portion  21  of the backrest cushion  2  to attach the backrest cushion  2  to the support bracket  1 . 
     However, the locking screw  20  are screwed and unscrewed by aid of a hand tool, such as a screwdriver, so as to assemble and disassemble the chair backrest, so that the chair backrest cannot be assembled and disassembled easily and quickly, thereby causing inconvenience to a user when assembling and disassembling the chair backrest. In addition, the locking screw  20  are unscrewed easily during a long-term utilization, so that the backrest cushion  2  is not combined with the support bracket  1  solidly and stably. Further, the locking screw  20  are easily missed after being unscrewed, thereby greatly causing inconvenience to the user when assembling and disassembling the chair backrest. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a chair backrest, comprising a support frame having an inner periphery provided with a support portion which has an upper edge provided with a plurality of locking blocks, and a backrest cushion having a periphery provided with an elastic snapping portion which is snapped onto the support portion of the support frame and retained by the locking blocks of the support frame. 
     Preferably, the support portion of the support frame has an upper end and a lower end each provided with a locking groove, and the support portion of the support frame has a right side and a left side each provided with a locking face. 
     Preferably, the snapping portion of the backrest cushion is compressible and retractable inwardly and elastically. 
     Preferably, the snapping portion of the backrest cushion functions as a locking bar. 
     Preferably, the locking blocks are formed on the upper edge of an upper end, a right side and a left side of the support portion of the support frame. 
     Preferably, the snapping portion of the backrest cushion is clamped between the locking grooves, the locking faces and the locking blocks of the support portion of the support frame, so that the backrest cushion is locked onto the support frame. 
     The primary objective of the present invention is to provide a chair backrest that is assembled and disassembled easily and quickly without needing aid of a hand tool. 
     Another objective of the present invention is to provide a chair backrest, wherein the backrest cushion is mounted on and detached from the support frame by forcing and retracting the snapping portion of the backrest cushion, so that the chair backrest is assembled and disassembled easily and quickly without needing aid of any hand tool, thereby facilitating the user assembling and disassembling the chair backrest, and thereby facilitating the user replacing the backrest cushion. 
     A further objective of the present invention is to provide a chair backrest, wherein the snapping portion of the backrest cushion is clamped between the locking grooves, the locking faces and the locking blocks of the support portion of the support frame, so that the backrest cushion is locked onto the support frame exactly and closely. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is an exploded perspective view of a chair backrest in accordance with the preferred embodiment of the present invention. 
         FIG. 2  is a longitudinal cross-sectional assembly view of the chair backrest as shown in  FIG. 1 . 
         FIG. 3  is a transverse cross-sectional assembly view of the chair backrest as shown in  FIG. 1 . 
         FIG. 4  is an exploded perspective view of a chair backrest in accordance with another preferred embodiment of the present invention. 
         FIG. 5  is a longitudinal cross-sectional assembly view of the chair backrest as shown in  FIG. 4 . 
         FIG. 6  is an exploded perspective view of a conventional chair backrest in accordance with the prior art. 
         FIG. 7  is a cross-sectional assembly view of the conventional chair backrest as shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 1-3 , a chair backrest in accordance with the preferred embodiment of the present invention comprises a support frame  3  and a backrest cushion  4 . 
     The support frame  3  is a substantially arc-shaped hollow frame. The support frame  3  has a narrower upper portion and a wider lower portion. The support frame  3  has a convex middle portion. The support frame  3  has an inner periphery provided with a support portion  31 . The support portion  31  of the support frame  3  has an upper end and a lower end each provided with a substantially semi-circular locking groove  311  and has a right side and a left side each provided with a locking face  312 . The support portion  31  of the support frame  3  has an upper edge provided with a plurality of locking blocks  32  each having an inner face provided with a barb-shaped tapered face. In the preferred embodiment of the present invention, the locking blocks  32  are formed on the upper edge of the upper end, the right side and the left side of the support portion  31  of the support frame  3 . 
     The backrest cushion  4  is a net-shaped body with a substantially arc-shaped profile. The backrest cushion  4  has a narrower upper portion and a wider lower portion. The backrest cushion  4  has a convex middle portion. The backrest cushion  4  has a periphery provided with a snapping portion  41  by sewing. The snapping portion  41  of the backrest cushion  4  is snapped onto the support portion  31  of the support frame  3  and retained by the locking blocks  32  of the support frame  3 . The snapping portion  41  of the backrest cushion  4  is formed by bending an elastic metallic hard bar. Thus, the snapping portion  41  of the backrest cushion  4  functions as a locking bar and is compressible and retractable inwardly and elastically. 
     In assembly, the snapping portion  41  (the locking bar) of the backrest cushion  4  is compressible and retractable inwardly and elastically so that the snapping portion  41  on any one of the four sides of the backrest cushion  4  is initially placed into the support portion  31  of the support frame  3 , abuts the respective locking groove  311  and the respective locking face  312 , and is clamped by the tapered faces of the locking blocks  32  respectively. Then, the snapping portion  41  on the other three sides of the backrest cushion  4  are retractable inwardly and elastically by a force (applied by a user) from the support frame  3  and are forced into the support portion  31  of the support frame  3 , abut the respective locking groove  311  and the respective locking face  312 , and are clamped by the tapered faces of the locking blocks  32  respectively. In such a manner, the backrest cushion  4  is mounted on and combined with the support frame  3  by the elastic inward retraction of the snapping portion  41 . In addition, the snapping portion  41  of the backrest cushion  4  is clamped between the locking grooves  311 , the locking faces  312  and the locking blocks  32  of the support portion  31  of the support frame  3 , so that the backrest cushion  4  is locked onto the support frame  3  exactly and closely. 
     On the contrary, the user only needs to provide a force on the snapping portion  41  on any one of the four sides of the backrest cushion  4  to force the snapping portion  41  to retract inwardly and elastically so as to release the snapping portion  41  of the backrest cushion  4  from the locking grooves  311 , the locking faces  312  and the locking blocks  32  of the support portion  31  of the support frame  3 , thereby detaching the backrest cushion  4  from the support frame  3 . Thus, the backrest cushion  4  is detached and removed from the support frame  3  easily and quickly. 
     Accordingly, the backrest cushion  4  is mounted on and detached from the support frame  3  by forcing and retracting the snapping portion  41  of the backrest cushion  4 , so that the chair backrest is assembled and disassembled easily and quickly without needing aid of any hand tool, thereby facilitating the user assembling and disassembling the chair backrest, and thereby facilitating the user replacing the backrest cushion  4 . In addition, the snapping portion  41  of the backrest cushion  4  is clamped between the locking grooves  311 , the locking faces  312  and the locking blocks  32  of the support portion  31  of the support frame  3 , so that the backrest cushion  4  is locked onto the support frame  3  exactly and closely. 
     Referring to  FIGS. 4 and 5 , the lower portion of the support frame  3 ′ has a middle portion provided with a mounting recess  33  located at an outer side of the support portion  31  of the support frame  3 ′ for mounting a retaining block  34  which abuts the snapping portion  41  of the backrest cushion  4  to clamp the snapping portion  41  of the backrest cushion  4  between the retaining block  34  and the support portion  31  of the support frame  3 ′. The retaining block  34  is secured in the mounting recess  33  by at least one locking screw  36 . The retaining block  34  has an inner side having a bottom provided with a substantially semi-circular or arc-shaped retaining groove  35  aligning with the respective locking groove  311  of the support portion  31  of the support frame  3 ′ to clamp the snapping portion  41  of the backrest cushion  4  between the retaining groove  35  of the retaining block  34  and the respective locking groove  311  of the support portion  31  of the support frame  3 ′. 
     Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.