Abstract:
A spring locking knob and a fixed stop at the upper ends of the front legs of a chair frame cooperate to restrict movement of a slideset joining the front legs, rear legs and seat support struts of a chair in making the chair more stable and resistant to an inadvertent folding closure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application corresponds to one filed Jun. 14, 2006 as PCT/CN/2006/001319. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Research and development of this invention and Application have not been federally sponsored, and no rights are given under any Federal program. 
       REFERENCE TO A MICROFICHE APPENDIX 
       [0003]    NOT APPLICABLE 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    This invention relates to collapsible chairs, in general, and to those provided with a back support, in particular. 
         [0006]    2. Description of the Related Art 
         [0007]    One of the problems associated with a typical design for a collapsible chair provided with a back is that the chair is not entirely stable, firm and safe. As such, it exhibits a tendency to lose its center of gravity, causing injury to the body. As will become clear from the following description, the collapsible chair of the present invention overcomes such problem. 
       SUMMARY OF THE INVENTION 
       [0008]    As will become clear, the collapsible chair of the first two embodiments of the present invention provides the stability by preventing the chair seat from collapsing upwardly if an extended force is applied downwardly on the rear of the seat, while the third embodiment provides the stability if the extended force is applied upwardly on the front. The center of gravity will be seen to be maintained in each, limiting any possible injury to a person sitting on the chair at such time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    These and other features of the present invention will be more clearly understood from a consideration of the following description, taken in connection with the accompanying drawings, in which: 
           [0010]      FIG. 1  is a pictorial drawing of the structure of a typically employed collapsible chair design in which its center of gravity can be lost, as representative of the collapsible chairs with a back typifying the prior art; 
           [0011]      FIGS. 2-5  are schematic diagrams helpful in understanding the first embodiment of the invention, in which  FIG. 3  shows the structure in its open state,  FIG. 4  shows the structure covered with a soft seating overlay, and  FIG. 5  shows the structure in its folded, closed state; 
           [0012]      FIGS. 6-9  are schematic diagrams helpful in an understanding of the second embodiment of the invention, in which  FIG. 7  illustrates the embodiment covered with a soft seat overlay,  FIG. 8  shows the embodiment in its half-folded state, and  FIG. 9  shows the embodiment completely folded and closed; and 
           [0013]      FIG. 10  is a schematic diagram of the third embodiment of the invention, with  FIG. 11  showing its structure in its folded, closed state. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    In the prior art collapsible chair with a back of  FIG. 1 , it will be noted that the chair is constructed with two inclined front legs  1 , and two rear legs  2 . The upper sides of the front legs  1  extend rearwardly and upwardly at an oblique angle in forming a support  3  for the back of the chair. The middle of a support  4  for the seat  5  is jointed with the front legs  1  on both sides by a pivot, as at  6 . The back of the support  4  is jointed with the rear legs  2  on both sides by a second pivot, as at  7 . A connecting plate  8  is included, jointed at both sides with the front legs  1  and rear legs  2 , as by a pivot at  9 . 
         [0015]    When the chair is opened and sat upon, the upper side of the rear legs  2  are intended to sustain pressures produced upon the middle of the front legs  1 . 
         [0016]    However, experience has shown a deficiency of this construction in that if an extended force is downwardly applied on the back of the seats, the front side of the seat begins to rise so that the entire chair loses its center of gravity. As a result, as the chair begins to close, the connecting plate  4  could easily injure a person sitting on the chair as the chair begins to fold up. 
         [0017]    The first two embodiments of the present invention, however, prevent the fold-up from happening. More specifically: 
         [0018]    A. In the collapsible chair embodiment of  FIGS. 2-5 , a modified construction for the chair is presented. Its two front legs are shown at  10 ,  11 , its two rear legs are shown at  12 ,  13  and two support struts for a seat frame are shown  14 ,  15 . A pair of sliding brackets, or slidesets  16 ,  17  are hinged at the upper ends of the rear legs  12 ,  13 , respectively, as by pivots  18 ,  19 , to slide along the upper length of the front legs  10 ,  11 . A fixed bracket or tube  20 , is secured to encircle the upper end of each front leg  10 ,  11  in limiting the upward movements of the slidesets  16 ,  17  in a manner to be described. The middle parts of the support struts  14 ,  15  are respectively jointed by pivots with the front legs  10 ,  11 , as at  21 ,  22 . The rear ends of the support struts  14 ,  15  are similarly pivot connected with the middle of the rear legs  12 ,  13 , as at  23 ,  24 . As will be appreciated, the interconnections between the front legs, the rear legs, and the support struts for the seat form “A” structures on both sides of the chair. 
         [0019]    As more clearly shown in  FIGS. 2 ,  3  and  5 , the front legs  10 ,  11  extend rearwardly and upwardly to join with a pair of extender struts  25 ,  26  for supporting the back of the chair. An overlay exists between the front leg  10  and left extender  25 , and between the front leg  11  and right extender  26  so that they may be fitted together and jointed by a pivot coupling through apertures provided on the extenders, as shown at  100  on the left extender  25 . A pair of cross support struts  30 ,  31  are hingeably connected, as at  32 ,  33  to secure at their lower ends to the front legs  10 ,  11 —for example, as by pivots  34 . A second pair of cross support struts  40 ,  41  are included, hinged at their upper ends to the extenders  25 ,  26  as by pivots at  42 ,  43 , at their lower ends to the lower portion of the rear legs  12 ,  13  as at  44 ,  45  and to each other, midway along their lengths, as at  46 . 
         [0020]    With the middle of the support struts  30 ,  31  being pivotally connected together as at  35 , and with their upper ends being pivotally connected to the seat support struts  14 ,  15 , as at  36 ,  37 , the front legs  10 ,  11 , the rear legs  12 ,  13 , the support struts  14 ,  15 , and the support struts  40 ,  41  form two “X” configurations jointed by a hinge in the middle. More specifically, both lower ends of the “X” configurations are jointed with the two front legs,  10 ,  11  by hinges at  33 ,  34 , and both upper ends of the “X” configurations are jointed with the support struts  14 ,  15  by the hinges  36 ,  37 . 
         [0021]    Such pivot or hinge connections will be understood to allow the middle part of the two front legs  10 ,  11  and the middle part of the two rear legs  12 ,  13  to be folded. Both upper ends of the cross support struts  30 ,  31  are bent and extend outwardly from the pivots  36 ,  37  at the seat support struts  14 ,  15  in forming an armrest for a cover for the seat. Such cover is shown at  50  in  FIG. 4 , with the armrests at  51 ,  52  to receive the bent extended portions  53  of the support struts  30 ,  31 . The two extenders  25 ,  26  will be seen from  FIG. 4  to also couple with the overlay  50  in providing the seat and back for the chair. 
         [0022]    A locking device for the slidesets  16 ,  17  is provided as it moves along the front legs  10 ,  11  towards the restrictor tubes  20 . The locking device shown in  FIGS. 2-5  includes a spring knob  55  set on each of the front legs  10 ,  11 . A recess is provided on the inside wall of each slideset  16 ,  17 , into which the spring knob  55  is configured to fit. A button  57  on each slideset is used to press the spring knob  55  out from the recess, on the outside wall of the slideset. As will be understood, an extended force exerted downwardly at the rear of cover for the seat is in a direction to collapse or fold the chair because of the various pivot connections, but once the slidesets move to the two restrictors, the spring knobs  55  slide into the recess. This locks up the two slidesets and the front legs  10 ,  11 , so that the slidesets can neither move further upwards nor downwards along the front legs. As a result, the support for the chair becomes more stable. Pressing the buttons  57  to release the spring knobs  55  from the recesses allows the slidesets to be released for sliding down the front legs so that the chair can be folded ( FIG. 5 ). 
         [0023]    When the chair according to this embodiment is opened, a soft seating cover  50  can be put in place as previously mentioned. Once the chair is to be stored away, the cover  50  is removed, and the chair can then be folded on a central axis to arrive at the configuration of  FIG. 5 . With this construction, the various supports are connected together side by side, in sharing the same set of front legs, rear legs and support struts for the seat in their respective pivoted connections. The construction allows the connected support struts to be folded in the central direction in accordance with the described hinged connections. 
         [0024]    B. The embodiments of  FIGS. 6-9  differ from those of  FIGS. 2-5  in the employment of horizontal armrests  60 ,  61 , the back end of which is jointed with the slidesets  16 ,  17  on the front legs  10 ,  11  by means of a further pivot or hinge  62 ,  63 . Between the armrests  60 ,  61  and the seat support struts  14 ,  15  are support poles or further struts  64 ,  65  that are joined with the supports  14 ,  15  by pivots  66 ,  67 . As with the embodiments of  FIGS. 2-5 , the two restrictors  20  limit the upward movement of the slidesets  16 ,  17  to prevent the folding of the chair by an extended force pushing down on the rear of the seat.  FIG. 7 , once again, shows the soft seating cover  50  in place, while  FIG. 8  shows the slidesets moving towards the restrictors  20  where they will eventually be stopped by the spring knob  55 . 
         [0025]    C. The embodiments of  FIGS. 10 and 11  will be appreciated as one where a hard seat  70  is fitted between the two support frame struts  14 ,  15  of  FIGS. 2-9 . Such seat  70  will be appreciated to either serve as a seat for the chair, or act as a supporting device for a seat between the front legs  10  and  11 , the rear legs  12 ,  13  and the support struts  14 ,  15 . A lateral support  71  is connected at the upper ends of the front legs  10 ,  11  via hinges at  72  on each leg. With this configuration, when the chair of  FIGS. 10 and 11  is folded (as by pulling up on the front of the seat or by pushing down on its rear), the front of the support struts  14 ,  15  rise rearwardly and upwardly.  FIG. 11  illustrates that the two front legs and the two rear legs cannot close as tightly together as in the embodiments of  FIGS. 2-5  and  6 - 9 . However, as with those embodiments, the restrictors  20  and spring knobs  55  continue to co-act with the slidesets  16 ,  17  to limit the fold-up of the chair—but to a point slightly less than fully closed. 
         [0026]    While there have been described what are considered to be preferred embodiments of the present invention, it will be readily appreciated by those skilled in the art that modifications can be made without departing from the scope of the teachings herein. For example, although various components of the folding chair of the invention have been described as being in the form of struts, its will be acknowledged that such components could also be in the form of tubes, poles, bars or like metallic members—and the term “struts” is intended to apply to each. For at least such reason, therefore, resort should be had to the claims appended hereto for a true understanding of the scope of the invention.