Patent Publication Number: US-6981742-B1

Title: Cushion for backrest of chair

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a cushion, and more particularly to a cushion for a backrest of a chair. 
   2. Description of the Related Art 
   A conventional cushion for a backrest of a chair in accordance with the prior art shown in  FIG. 9  comprises a curved main body  50  having a first end formed with a fixed portion  51  and a second end formed with a movable portion  52 , an adjusting device  53  mounted on the fixed portion  51  of the main body  50 , and a guide wire  54  having a first end connected to the movable portion  52  of the main body  50  and a second end connected to the adjusting device  53 . Thus, the guide wire  54  is driven and moved by operation of the adjusting device  53  to pull or release the movable portion  52  of the main body  50  so as to adjust the curvature of the main body  50 . 
   However, the curvature of the main body  50  is changed by operation of the adjusting device  53 , so that the curvature of the main body  50  cannot be adjusted automatically, thereby causing inconvenience to a user in adjustment of the curvature of the cushion. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, there is provided a cushion, comprising:
         a flexible curved main body having a first end formed with a fixed portion and a second end formed with a movable portion; and   an elastic mechanism mounted on the main body and biased between the fixed portion and the movable portion of the main body.       

   The primary objective of the present invention is to provide a cushion whose curvature can be adjusted automatically so as to fit users of different statures. 
   Another objective of the present invention is to provide a cushion, wherein the elastic mechanism is stretched by the pulling action of the movable portion of the main body to counteract the user&#39;s weight and to mate with variation of the curvature of the main body, so that when the main body is pressed and deformed by the user&#39;s weight, the main body has a greater elastic action, and the curvature of the main body is arbitrarily changed in an automatic manner by the elastic force of the elastic mechanism, so as to fit users of different statures and weights. 
   A further objective of the present invention is to provide a cushion that only needs to provide the elastic mechanism to reach the purpose of changing the curvature of the cushion arbitrarily, thereby decreasing costs of fabrication. 
   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 DRAWINGS 
       FIG. 1  is an exploded perspective view of a cushion in accordance with the preferred embodiment of the present invention; 
       FIG. 2  is a side plan assembly view of the cushion as shown in  FIG. 1 ; 
       FIG. 3  is a schematic operational view of the cushion as shown in  FIG. 2  in use; 
       FIG. 4  is a schematic operational view of the cushion as shown in  FIG. 3  in use; 
       FIG. 5  is a schematic operational view of the cushion as shown in  FIG. 3  in use; 
       FIG. 6  is an exploded perspective view of a cushion in accordance with another embodiment of the present invention; 
       FIG. 7  is a side plan assembly operational view of the cushion as shown in  FIG. 6 ; 
       FIG. 8  is an exploded perspective view of a cushion in accordance with another embodiment of the present invention; and 
       FIG. 9  is an exploded perspective view of a conventional cushion in accordance with the prior art. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the drawings and initially to  FIGS. 1–3 , a cushion in accordance with the preferred embodiment of the present invention comprises a flexible curved main body  10  having a first end formed with a fixed portion  11  and a second end formed with a movable portion  12 , and an elastic mechanism  2  mounted on the main body  10  and biased between the fixed portion  11  and the movable portion  12  of the main body  10 . 
   The elastic mechanism  2  includes a tensile spring  21  having a first end secured on the fixed portion  11  of the main body  10  and a second end secured on the movable portion  12  of the main body  10 . 
   The fixed portion  11  of the main body  10  has a mediate portion formed with a substantially inverted L-shaped support plate  13  mounted on the first end of the tensile spring  21  of the elastic mechanism  2 . The support plate  13  of the fixed portion  11  has a distal end formed with a planar support face  130  to support the first end of the tensile spring  21  of the elastic mechanism  2 . The support face  130  of the support plate  13  is formed with a through hole  132 , and the first end of the tensile spring  21  is provided with a threaded rod  210  extended through the through hole  132  of the support face  130 . A nut  211  is screwed onto the threaded rod  210  of the first end of the tensile spring  21  and rested on a side of the support face  130  of the support plate  13 . 
   The movable portion  12  of the main body  10  has a mediate portion formed with a support block  120  mounted on the second end of the tensile spring  21  of the elastic mechanism  2 . The support block  120  of the movable portion  12  is formed with a through hole  122 , and the second end of the tensile spring  21  is provided with a threaded rod  212  extended through the through hole  122  of the movable portion  12 . A nut  213  is screwed onto the threaded rod  212  of the second end of the tensile spring  21  and rested on a side of the movable portion  12 . 
   As shown in  FIG. 3 , the fixed portion  11  of the main body  10  is fixed on a backrest  201  of a chair  20 , and the movable portion  12  of the main body  10  is pulled by the elastic force of the tensile spring  21  of the elastic mechanism  2 , so that the main body  10  is pulled by the tensile spring  21  to have a smaller curvature. 
   As shown in  FIGS. 4 and 5 , when a user&#39;s back is rested on the main body  10  of the cushion, the main body  10  is pressed and deformed by the user&#39;s weight to form a greater curvature and to pull the movable portion  12  outward, so that the curvature of the main body  10  is changed by the pressure of the user&#39;s weight. In such a manner, the tensile spring  21  of the elastic mechanism  2  is stretched by the pulling action of the movable portion  12  of the main body  10  to counteract the user&#39;s weight and to mate with variation of the curvature of the main body  10 , so that the main body  10  has a greater elastic action, and the curvature of the main body  10  is arbitrarily changed in an automatic manner by the elastic force of the tensile spring  21  of the elastic mechanism  2 , so as to fit users of different statures and weights. 
   Referring to  FIGS. 6 and 7 , the elastic mechanism  2  includes a support rod  3  having a first end extended through the support plate  13  of the fixed portion  11  and a second end secured on the movable portion  12  of the main body  10 , and a compression spring  22  mounted on the support rod  3  and urged between the support plate  13  of the fixed portion  11  and the first end of the support rod  3 . The first end of the support rod  3  is provided with an urging plate  30  rested on a first end of the compression spring  22  which has a second end rested on a side of the support face  130  of the support plate  13 . The support rod  3  is slidably mounted in the through hole  132  of the support face  130 . The second end of the support rod  3  is formed with an outer thread  32  extended through the through hole  122  of the movable portion  12 . A nut  31  is screwed onto the outer thread  32  of the support rod  3  and rested on a side of the movable portion  12 . 
   Referring to  FIG. 8 , the movable portion  12  of the main body  10  has a mediate portion formed with a locking slot  17 , the support face  130  of the support plate  13  is formed with a mounting hole  134 , the elastic mechanism  2  includes a tensile spring  24  having a first end secured on the support plate  13  of the fixed portion  11 , and the cushion further comprises a guide tube  4  slidably mounted in the mounting hole  134  of the support plate  13  and having a first end provided with a fixing rod  41  locked in the locking slot  17  of the movable portion  12  and a second end provided with a fixing plate  410  locked on a second end of the tensile spring  24 . 
   Accordingly, the elastic mechanism  2  is stretched by the pulling action of the movable portion  12  of the main body  10  to counteract the user&#39;s weight and to mate with variation of the curvature of the main body  10 , so that when the main body  10  is pressed and deformed by the user&#39;s weight, the main body  10  has a greater elastic action, and the curvature of the main body  10  is arbitrarily changed in an automatic manner by the elastic force of the elastic mechanism  2 , so as to fit users of different statures and weights. In addition, the cushion only needs to provide the elastic mechanism  2  to reach the purpose of changing the curvature of the cushion arbitrarily, thereby decreasing costs of fabrication. 
   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.