Chair Backrest

Abstract

A chair backrest comprises a closed loop frame, a net, a frame cover, and the subsidiary supporting-arms. The frame includes a protruding loop edge, defining a global frame-net interface with frame fixing holes therein. A loop-like net fixing piece is used for nailing the border of the net onto the frame-net interface. The subsidiary supporting-arms consists of a pair of branching poles; the ends of the branching poles are connected to a common base with the upper portion of the poles fixed to the frame by frame-arm fixing devices and frame-arm fixing pieces. A back reinforcement board traversing between the right side and the left side of the frame can be added to the rear side of the frame to further support the frame against forces applied.

1 . A chair backrest comprising:
 a frame made of hard plastics shaped like a closed loop with frame fixing holes, wherein
 the outer front loop-like edge of said frame protrudes outwards facing a chair occupant's back, defining a loop-like frame-net interface with a sharp angle, wherein said frame-net interface being confined by said front loop-like edge and the opposing rear periphery of said frame; said frame-net interface is formed with frame-net fixing holes; 
 on each the right and left side of the rear of said frame is formed a frame-arms fixing section, defining an inner groove and frame-arms connection holes for engagement; 
   a net fixing piece;   a net made from soft materials with the border of said net secured onto said frame-net interface by said net fixing piece;   a frame cover shaped like a closed loop for mounting over said frame-net interface;
 said frame cover is configured with cover-fixing bores at locations corresponding to said frame-net fixing holes; 
 along the inner surface of said frame cover is formed a loop-like suppressing lock for stabilizing in position the border of said net and said net fixing piece underneath; and 
   a supporting-arms assembly with branching V-like supporting poles; the upper portion of each said supporting poles connects to said frame-arms fixing section of said frame.   
   
   
       2 . The chair backrest as claimed in  claim 1  wherein said net fixing piece is a nailing loop. 
   
   
       3 . The chair backrest as claimed in  claim 1  wherein said supporting-arms assembly comprises:
 two supporting poles, shaped in a V-like branch from bottom to top, with frame-arm fixing bores at the upper portion of said supporting poles;   a base plate to which the bottom ends of said two poles connect; and   frame-arm fixing pieces for engaging the upper portion of each said supporting pole to said frame-arms fixing section of said frame; each said frame-arms fixing piece defines an inner pole-fixing groove and a pole-fixing bore for fasteners to go through.   
   
   
       4 . The chair backrest as claimed in  claim 1  wherein said frame is made from hard plastics, while said supporting poles and said base plate are made of metals. 
   
   
       5 . The chair backrest as claimed in  claim 1  wherein said frame is reinforced with a frame supporting board, traversing between the right and left side of said frame in a curve way toward the rear of said frame.