Patent Abstract:
A sling chair includes a back frame member having side rails held in substantially parallel relation by a pair of cross bar members. In one embodiment, the cross bar members are generally curved so as to extend away from the back faces of the side rails, forming a concave back structure which can receive a sling member and, eventually, a seated occupant. The cross bar members are adapted to retain the sling member in secure fashion through upper and lower backrest assemblies, resulting in better support and more efficient assembly. This also facilitates separate provisioning of decorative features to improve the chair&#39;s aesthetic qualities.

Full Description:
FIELD OF THE INVENTION 
   The present invention relates to chair constructions, and more particularly relates to a chair construction employing a sling-type backrest which promotes chair stability, comfort and a variety of design alternatives. 
   BACKGROUND OF THE INVENTION 
   Various types of sling chairs have been known which provide a somewhat concave and/or giving backrest. Such chairs generally include a back portion and a seat portion, and may optionally include armrest portions. The back portion generally includes a back frame and a flexible yet supportive backrest made of fabric or other suitable material and mounted to the back frame. Different mechanisms have been employed for securing the backrest to the back frame, and these prior art mechanisms have suffered from several deficiencies. First, these prior art mechanisms often fail to provide a secure connection, which can result in the backrest being unsupportive of the seated individual. Further, the sling backrest for these chairs is frequently retained along the chair side rail supports, creating side-to-side sling tension, restricting the potential to add decorative chair features, and complicating assembly. 
   SUMMARY OF THE INVENTION 
   The present invention provides a connection assembly for a sling chair which allows for efficient chair assembly and results in a comfortable yet sturdy chair. The present invention includes a back frame member having side rails held in substantially parallel relation by a pair of cross bar members. In one embodiment, the cross bar members are generally curved so as to extend away from the back faces of the side rails, forming a concave back structure which can receive a sling member and, eventually, a seated occupant. The cross bar members are adapted to retain the sling member in secure fashion through upper and lower backrest assemblies. In this way, the sling member is not secured to the side rails, but rather to the cross bar members, resulting in better support, a more secure connection and more efficient assembly. The method of securing the sling member using a detachable support bar having a scaffold support element ensures that the sling member is efficiently and securely retained. The present invention also facilitates separate provisioning of decorative features to improve the chair&#39;s aesthetic qualities. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a right side view of an exemplary chair showing one embodiment of the present invention. 
       FIG. 2  is a rear elevational view of the back frame and backrest elements of the chair assembly of the present invention. 
       FIG. 3  is a bottom cross-sectional view of the upper backrest assembly of one embodiment of the present invention, taken along the line III-III of  FIGS. 1 and 2 . 
       FIG. 4  is a bottom plan view of one embodiment of the bottom cross bar member of the present invention. 
       FIG. 5  is a right side cross-sectional view of the upper backrest assembly portion of one embodiment of the present invention, taken along the line V-V of  FIGS. 2 and 3 . 
       FIG. 6  is a right side cross-sectional view of the lower backrest assembly portion of one embodiment of the present invention, taken along the line VI-VI of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIGS. 1 through 6 , the present invention provides a single frame sling chair  10 , having a rigid frame  12 .  FIG. 1  shows an overall, right side view of one embodiment of a chair according to the present invention, including monolithic welded frame  12  comprising frame rails  14 , seat  16 , armrests  18  and leg portions  20 . A backrest assembly  22  is also shown, including upper backrest assembly portion  24  and lower backrest assembly portion  26 . Upper backrest assembly portion  22  includes top cross bar  28  and detachable support bar  30 , described more completely hereafter. Top cross bar  28  may be integrally formed with top element  32  and connective fascia  34 , or may be secured to elements  32  and  34  as separate members. Top cross bar is secured to, and acts as a spreader between, frame side rails  14 , as shown in  FIG. 2 . 
   As further shown in  FIGS. 1 and 2 , lower backrest assembly portion  26  includes bottom cross bar  38  which is secured to frame rails  14  and acts as a spreader to hold frame rails  14  apart. Bottom cross bar  38  cooperates with top cross bar  28  to hold frame rails  14  in substantially parallel relation. A backrest  33 , such as a sling fabric member, is secured to the upper  24  and lower  26  backrest assembly portions to provide body support to individuals using the chair of the present invention. 
   In the embodiment as shown in  FIG. 2 , top and bottom cross bar members are provided in substantially parallel relation. The crossbars  28 ,  38  are provided of a curved or concave shape generally, and can be solid or hollow. As shown in  FIGS. 1 and 2 , the crossbars  28 ,  38  project at least partially outwardly away from respective back faces  15  of side rails  14 . The crossbars  28 ,  38  can be any of a variety of section shapes, and can be adapted to accept a decorative casting  34  as part of or an attachment to crossbar, as shown in the exemplary embodiment of  FIG. 2 . Decorative side castings  35  can also be provided as shown in  FIG. 2  so as to flank sling member  33 . The sectional shape of side rails  14  as well as that of support bar  30  can be circular, oval, square, or other shape, for example. Further, support bar  30  and side rails  14  can be solid or hollow. 
   The remainder of the chair frame can have any arrangement for a seat bottom, it may have arms or no arms, and it may have any number of legs, or a pedestal instead of legs, and may be a rocker, swivel chair, swivel-rocker, swivel-glider, or a rigid monolithic frame. 
   The method of securing top  28  and bottom  38  cross bar members to back frame rails  14  can be by conventional means, such as by welding or by providing the frame rails with open interior slots for receiving respective ends of cross bar members  28 ,  38  (not shown). The method of securing backrest  33  to top and bottom cross members involves upper  24  and lower  26  backrest assemblies. Upper backrest assembly  24  comprises at least top cross bar member  28  and detachable support bar  30 . As shown in  FIGS. 2 ,  3  and  5 , detachable support bar  30  is provided with a base portion  41  and a scaffold portion  42 , wherein scaffold portion can be “c”-shaped as shown for receiving a substantially rigid rod  50 . As shown in  FIG. 5 , rod member  50  is placed through a loop  40  in sling member  33 , wherein the sling loop  40  and rod  50  rest in the channel created by scaffold portion  42 . Loop  40  can be formed, for example, by bending sling member edge back upon itself and securing the sling member to itself, such as via a hem or similar method. A portion of sling member  33  thus rests in the gap  43  created by the base portion  41  and cross bar member  28 . The support bar  30  can be secured to the bottom face  45  of top cross bar  28  using screws  46  mating with internal threads  47  in base portion  41  and cross bar  28 , for example. Alternative means of fastening support bar  30  to top cross bar  28  can be employed, such as sheet metal screws, hook and loop fasteners, clamps, or malleable plug members extending from support bar  30  into openings in cross bar  28 , for example. 
   As shown in  FIGS. 2 ,  4  and  6 , lower backrest assembly  26  comprises at least bottom cross bar  38  and rod member  60 . As shown in  FIGS. 2 and 6 , bottom cross bar  38  can include an upper portion  52  and a lower portion  53  which join together at respective ends  38   a  and  38   b , and which have respective inside walls  54   a  and  54   b , outside walls  55   a  and  55   b  and interior facing walls  56   a  and  56   b . Cross bar member  38  can be formed as a unitary, monolithic piece or can be formed by securing respective portions  52  and  53  together at ends  38   a  and  38   b  through welding or other attachment means. Regardless of how formed, the interior facing walls  56   a  and  56   b  cooperate to form a through-and-through slot  44 . As shown in  FIG. 2 , slot  44  can extend for substantially the length of upper  52  and lower  53  portions. As shown in  FIG. 6 , the end of fabric sling  33  opposite the end secured to upper bracket assembly is provided with a loop  58  for receiving rod member  60 . Loop  58  can be formed in a manner similar to that described for forming loop  40 . Rod member and sling loop portion  58  are then retained against outside walls  55   a  and  55   b , which are respectively provided with inwardly extending portions  57   a  and  57   b  for such purpose. In one embodiment as shown in  FIG. 6 , inwardly extending portions  57   a  and  57   b  are arcuate in cross-section. Portions  57   a  and  57   b  assist in providing the back assembly  22  with a low profile, minimizing the extent of rod and sling extension outside of the plane formed by outside walls  55   a  and  55   b , which in turn minimizes sling member exposure to unnecessary wear and tear. As shown in  FIGS. 4 and 6 , the securing of sling member  33  within lower bracket assembly  26  can be optionally enhanced through the employment of one or more machine screws  64  extending through openings  66  in lower cross bar member and mated with hollow receiving screw  65  or other similar securing element. In one embodiment of the invention, a screw receiving member such as a nut having an interior threaded surface is maintained within walls of cross bar  38  so as to receive screw  64  while not extending outwardly of the upper portion  52  of cross bar  38 . In this way, minimum visibility of attachment elements such as nuts and bolts can be maintained, which enhances the aesthetic qualities of the present invention. 
   It will be appreciated that the shape of top  28  and bottom  38  cross bar members can be adapted to suit particular chair requirements in accordance with the present invention. For example, the top cross bar member  28  can have a rounded rectangle cross-sectional shape, as shown in  FIG. 5 , or can have a square, hexagonal, octagonal or other polygonal shape. Bottom cross bar member  38  can have a primarily rectangular shape with arcuate interior wall segments  57   a  and  57   b  as shown in  FIG. 6  and described earlier. Alternatively, bottom cross bar member  38  can have a square, hexagonal, octagonal or other polygonal shape. In one embodiment, bottom cross bar member  38  has an octagonal shape and adjacent edges establish a receiving channel for retaining rod member  58  and looped hem  60 , again minimizing the outward extension of the sling fabric loop and rod member beyond the lower backrest assembly. In a further embodiment, a metal frame member (not shown) can be secured to upper  52  and lower  53  portions of bottom cross bar member  38  to conceal and protect sling member  33  and loop  60 . 
   By placing the sling entrapment at the top and bottom in the cross members, rather than in the side rails, the invention facilitates the creation of a comfortable concave shape to the back rest. Also, the invention thereby allows for shorter looped hems and dowels than would exist if the sling were attached to the side rails. The invention also permits sturdier and more rigid frame construction and leaves open more design possibilities for accessory items. 
   The method of assembling the backrest  22  to the frame  12  according to the present invention can occur in several ways. In one exemplary way, chair frame  12  is provided with top cross bar member  28  and bottom cross bar member  38  secured to side rails  14  as shown in  FIG. 2 . Sling member  33  is provided with looped hems  40  and  58  at two ends thereof. Looped end  58  is manipulated through slot  44  in lower cross bar member so as to be positioned somewhat adjacent to wall portions  57   a  and  57   b . Rod member  60  is then manipulated through looped end  58  such that any tension applied to the remainder of sling member, such as pulling on sling member from a location on the interior of lower cross bar member, will result in looped hem  58  contacting wall portions  57   a  and  57   b . Machine screws and nuts or equivalent attachment means can assist in retaining sling member in place with respect to bottom cross bar member  38 . 
   Next, rod member  50  is placed through looped hem portion  40  of sling member  33 , and this arrangement is positioned over base portion  41  of support bar  30  and within scaffold portion  42 . Support bar  30  is then raised so as to align with the under face  45  of top cross bar member  28 . Threaded bolts  46  or similar attachment means can then be manipulated through base portion  41 , sling member  33  and top cross bar member  28  to securely maintain support bar and sling to top cross bar member  28 . 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the claims of the application rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Technology Classification (CPC): 0