Patent Publication Number: US-7588297-B1

Title: Shaped fabric chair diaphragm and method of forming same

Description:
FIELD OF THE INVENTION 
   This invention relates generally to a fabric diaphragm for a chair seat and backrest, and more particularly to the construction and method of applying fabric on a chair frame. 
   BACKGROUND OF THE INVENTION 
   Fabric diaphragms for seat and backrest of a cushioned chair used in, for example, airplanes are typically stretched between or around two tubes so as to create a flexible surface on which a cushion may be placed and the passenger is seated. The diaphragm is stretched flat across (or front to back). In cases where the tubes are straight, the fabric also will be stretched straight. In cases where the frame is contoured, the diaphragm will follow the contours of the frame, but will still be stretched straight across. Stretching the diaphragm to form a generally flat, non-contoured surface does not provide an optimally comfortable surface upon which to sit for a prolonged duration. 
   It is therefore an object of the present invention to provide a shaped fabric diaphragm for the seat and backrest of a chair which overcomes the drawbacks of prior fabric diaphragms. 
   SUMMARY OF THE INVENTION 
   In an aspect of the present invention, a support diaphragm for a seat or backrest of a chair includes a support frame having laterally spaced first and second support portions. A support material includes a flexible sheet extending from and generally tensioned between the first support portion and the second support portion to form a front portion, and extending from and generally tensioned between the first support portion and the second support portion to form a back portion spaced from and in underlying relationship to the front portion. A strut is coupled at a first lateral end to the front portion of the support material and coupled at a second lateral end to the back portion of the support material. The strut lengthwise extends along the support material in at least one predetermined direction relative to a direction of tension in the support material. The strut is configured to provide generally no resistance to movement of the front portion and the back portion toward each other when pressure is applied to the front portion, and a width of the strut between the first lateral end and the second lateral end provides a desired amount of contouring of the front portion of the support material. 
   In a second aspect of the present invention, a method of forming a support diaphragm for a chair seat or backrest includes extending and generally tensioning a flexible sheet of support material between laterally spaced first and second support portions of a support frame to form a front portion. The flexible sheet of support material is extended to and generally tensioned between the laterally spaced first and second support portions of the support frame to form a back portion spaced from and in underlying relationship to the front portion. A strut is coupled at a first lateral end to the front portion of the support material and is coupled at a second lateral end to the back portion of the support material such that the strut lengthwise extends along the support material in at least one predetermined direction relative to a direction of tension in the support material. The strut is configured to provide generally no resistance to movement of the front portion and the back portion toward each other when pressure is applied to the front portion, and a width of the strut between the first lateral end and the second lateral end is configured to provide a desired amount of contouring of the front portion of the support material. 
   In a third aspect of the present invention, a support diaphragm for a backrest of a chair includes a support frame including laterally spaced first and second support portions. A support material includes a flexible sheet extending from and generally tensioned between the first support portion and the second support portion to form a front portion, and extending from and generally tensioned between the first support portion and the second support portion to form a back portion spaced from and in underlying relationship to the front portion. The front portion is configured as a backrest including a lumbar area fabricated from a generally non-stretchable material and a remaining area of the front portion fabricated from a generally stretchable material. A strut is coupled at a first lateral end to the front portion of the support material and coupled at a second lateral end to the back portion of the support material. The strut lengthwise extends along the support material in at least one predetermined direction relative to a direction of tension in the support material. The strut is configured to provide generally no resistance to movement of the front portion and the back portion toward each other when pressure is applied to the front portion. A width of the strut between the first lateral end and the second lateral end is configured to provide a desired amount of contouring of the front portion of the support material. 
   In a fourth aspect of the present invention, a support diaphragm for a seat or backrest of a chair includes a support frame including laterally spaced first and second support portions. A support material includes a flexible sheet extending from and generally tensioned between the first support portion and the second support portion to form a front portion, and extending from and generally tensioned between the first support portion and the second support portion to form a back portion spaced from and in underlying relationship to the front portion. At least a portion of the front portion is fabricated from a generally stretchable material, and the back portion is fabricated from a generally non-stretchable material. A strut is coupled at a first lateral end to the front portion of the support material and coupled at a second lateral end to the back portion of the support material. The strut lengthwise extends along the support material in at least one predetermined direction relative to a direction of tension in the support material. The strut is configured to provide generally no resistance to movement of the front portion and the back portion toward each other when pressure is applied to the front portion. A width of the strut between the first lateral end and the second lateral end is configured to provide a desired amount of contouring of the front portion of the support material. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a support diaphragm for a chair seat or backrest embodying the present invention. 
       FIG. 2  is a perspective of a prior art support diaphragm for a chair seat or backrest. 
       FIG. 3  is a flow diagram illustrating a method of forming a support diaphragm for a chair seat or backrest in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIG. 1 , a support diaphragm for a chair seat or backrest embodying the present invention is generally indicated by the reference number  10 . The support diaphragm  10  comprises a generally rigid support frame  12  including laterally spaced first and second support portions  14 ,  16 . As shown in  FIG. 1 , The support frame  12  includes a central portion  18  coupled at longitudinal ends to the first and second support portions  14 ,  16  to form a generally U-shaped support frame, but may take other practical shapes. 
   The support diaphragm  10  further comprises a support material  20  including a flexible sheet extending from and generally tensioned between the first support portion  14  and the second support portion  16  to form a front portion  22 . The flexible sheet of support material  20  further extends from and is generally tensioned between the first support portion  14  and the second support portion  16  to form a back portion  24  spaced from and in underlying relationship to the front portion  22 . More specifically, the front portion  22  of the support material  20  preferably is generally tensioned around one or both of the first and second support portions  14 ,  16  and extends to the other support portion to form the back portion  24 . When tensioned around the support portions  14 ,  16 , the front portion  22  and the back portion  24  are formed from a continuous flexible sheet of the support material  20 . 
   The support diaphragm  10  further comprises at least one strut  26  coupled at a first lateral end  28  to the front portion  22  of the support material  20 , and coupled at a second lateral end  30  to the back portion  24  of the support material  20 . In an exemplary embodiment the strut  26  is sewn to the support material  20 , but may be coupled to the support material by other practical means without departing from the scope of the present invention. The strut  26  lengthwise extends along the support material  20  in at least one predetermined direction relative to a direction of tension or in which the support material is being stretched onto the support portions  14 ,  16 . More specifically, the strut  26  can lengthwise be straight, curved, forming angles, or have lengthwise portions that are a combination of shapes such as straight, curved or forming angles from one lengthwise end to the other. Moreover, the strut  26  can lengthwise extend in any direction relative to the direction of tension in the support material  20 . In other words, the strut  26  can lengthwise extend in a direction having an angle ranging from that of parallel to perpendicular to the direction of tension in the support material  20 . The strut  26  is configured to provide generally no resistance to movement of the front portion  22  and the back portion  24  toward each other when pressure is applied to the front portion. Although two struts  26  are shown in  FIG. 1 , it should be understood that any number of struts having the same or different lengths, widths, lengthwise direction, and material construction relative to each other can be employed without departing from the scope of the present invention. 
   A width of the strut  26  between the first lateral end  28  and the second lateral end  30  is configured to provide three-dimensional shape to the diaphragm, or more specifically to provide a desired amount of contouring of the front portion  22  of the support material  20  by pulling the front portion  22  and the back portion  24  toward each other relative to the spacing between the front portion and the back portion without the strut. The width of the strut  26  can be non-uniform along the lengthwise direction to provide variable amounts of contouring along different portions of the front portion  22  of the support material  20 . The width of the strut  26  when relatively short pulls the front portion  22  and the back portion  24  closer together than when the width of the strut is relatively long. Moreover, the width of the strut  26  can be chosen at locations to be long enough to provide no localized contouring of the front portion  22 . 
   As shown in  FIG. 1 , for example, the width of the strut  26  progressively tapers along the lengthwise direction to provide the variable amounts of contouring along different portions of the front portion  22  of the support material  20 . Although the width of the strut  26  is illustrated as being progressively tapered by way of example, it should be understood that the width of the strut can take on any variation from one lengthwise end to the other lengthwise end. For example, the width of the strut  26  can be constant, progressively taper, or can increase and then decrease at least once along the lengthwise extent of the strut in order to custom contour the support material  20 . 
   The flexible sheet of support material  20  and the strut  26  are preferably made of fabric, but can be made of other practical flexible materials without departing from the scope of the present invention. In sum, contouring is introduced to the support diaphragm  10  through the sewing process and is further achieved when the support material  20  is under tension. 
   Contouring of the support material  20  provides several benefits as follows: 
   1) the support diaphragm in its three-dimensional configuration can be designed to conform to the body of the occupant better than a diaphragm stretched flat side to side (or front to back, if oriented in that direction), and 
   2) the seat requires less foam to distribute load than would otherwise be necessary, or the seat can be made without foam because the support diaphragm can cradle the occupant in the seat without the use of foam. 
     FIG. 2  illustrates a conventional support diaphragm  50  which is similar to the support diaphragm  10  except that the conventional support diaphragm does not include struts. Consequently, the conventional support diaphragm  50  is generally stretched flat and does not provide contouring of the support material  20  for user comfort. 
   Referring again to  FIG. 1 , for additional user comfort, the support material  20  forming the front portion  22  can be fabricated from a generally stretchable material to conform to the body shape of the user. Some areas of the support material  20  covering the front portion  22  can be fabricated from a generally non-stretchable material where additional support or firmness may be desirable. As shown in  FIG. 1 , for example, a lumbar area  31  of the front portion  22  when used as a backrest can be fabricated from a generally non-stretchable material, and a remaining area  32  of the front portion can be fabricated from a generally stretchable material. 
   The stretchable material is preferably a synthetic fiber which exhibits a 3% to 9% stretch when stretched onto a seat frame under tension. The stretchable material is preferably disposed on front and side surfaces of the support diaphragm used as a backrest, and disposed on top and sides of the support diaphragm used as a seat. Alternatively, the stretchable material can be disposed over the whole diaphragm or other predetermined portions thereof. 
   Material on the back portion of a support diaphragm used as a backrest, and bottom side of the bottom diaphragm is preferably non-stretchable. For example, the non-stretchable material includes a polyester fabric that has low stretch characteristics. Such non-stretchable material is lighter weight than the stretchable material and thus reduces the overall weight of the diaphragm system. Because it does not stretch, it also pulls the fabric diaphragm to the rear for a backrest, and to the bottom for a bottom cushion more than it would if the stretchable fabric were used. 
   The support diaphragm may be slid onto a seat frame, or alternatively, zippers may be used for installation of the support diaphragm. Zippers are located on the back side of the backrest support diaphragm or on the bottom side of the bottom or seat support diaphragm. In this instance, the diaphragm is placed around the side supports and the zipper is closed, thereby linking the material around the supporting members and stretching the material by the preferred amount. The zipper is longer than the diaphragm, thus allowing the closure to begin and pull the material together. 
   An example of a method of forming a support diaphragm for a chair seat or backrest is illustrated by the flow diagram of  FIG. 3 . A flexible sheet of support material is extended and generally tensioned between laterally spaced first and second support portions of a support frame to form a front portion (step  100 ). The flexible sheet of support material is extended to and generally tensioned between the laterally spaced first and second support portions of the support frame to form a back portion spaced from and in underlying relationship to the front portion (step  102 ). The steps of generally tensioning preferably include generally tensioning the front portion of the support material around at least one of the support portions and extending the support material to the other support portion to form the back portion. A strut is coupled (preferably sewn) at a first lateral end to the front portion of the support material and is coupled (preferably sewn) at a second lateral end to the back portion of the support material such that the strut lengthwise extends along the support material in at least one predetermined direction relative to a direction of tension in the support material (step  104 ). The strut material is configured to provide generally no resistance to movement of the front portion and the back portion toward each other when pressure is applied to the front portion, and a width of the strut between the first lateral end and the second lateral end is configured to provide a desired amount of contouring of the front portion of the support material (step  106 ). 
   As will be recognized by those of ordinary skill in the pertinent art, numerous modifications and substitutions can be made to the above-described embodiments of the present invention without departing from the scope of the invention. Accordingly, the preceding portion of this specification is to be taken in an illustrative, as opposed to a limiting sense.