Back rest for seat back

Abstract

The invention provides a back rest for a seat back which will not exert too much burden on the thoracic vertebrae and the lumbar vertebrae, resulting in the likelihood of accumulation of fatigue or pain in the lower back after a long hour driving being reduced being reduced. The back rest has a front side having a slight concave extending from the intermediate portion to the upper portion thereof and a convex extending from said intermediate portion to the lower portion, thus forming a configuration following an S line of the human spinal column while having a reverse side provided with reinforcement ribs together with a plurality of slits generally formed in said back rest.

What is claimed is:  
     
         1 . A back rest for a seat back, said back rest having a front side and a reverse side, which back rest comprises a slight concave extending from substantially an intermediate portion of said front side to an upper portion thereof; a slight convex extending from said intermediate portion to a lower portion of said front side to form in combination a configuration following an S line of the human spinal column; and ribs provided for reinforcement at said reverse side, said back rest being generally formed with a plurality of apertures.  
     
     
         2 . A back rest as set forth in  claim 1 , wherein said back rest slightly curves from right to left to enclose a human back.  
     
     
         3 . A back rest as set forth in any one of claims  1  and  2 , wherein said apertures are a plurality of slits.