Patent Abstract:
A spring back hinge interconnects a backrest frame to a chair seat frame or is mountable to just the chair base frame, the spring back hinge being optionally fittable with a lever actuated locking assembly and the spring back hinge being fittable on a single side or both sides, alternative back rest frames being fittable to the spring back hinge.

Full Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority based on U.S. Provisional Application Ser. No. 61-558,808 filed Nov. 11, 2001. Additionally, embodiments may utilize a spring arrangement taught in co-pending application Ser. No. 10-595,330, also published as Publication No. 2007-0040311 on Feb. 22, 2007, which disclosures are incorporated by reference as if full set forth herein. 
     
    
     BACKGROUND 
     Field of Invention 
       [0002]    The present technology relates generally to backrest adjustment, and more particularly to a flexible hinge that allows a backrest to rock and a spring lock to allow or inhibit the backrest to rock. 
       SUMMARY 
       [0003]    A spring back hinge with or without a spring lock mechanism is provided for a backrest. The spring back hinge is mounted on a left, right or both left and right side of a backrest frame that and provides spring in the back frame to allow a user to “rock” the backrest fore and aft independent of a fixed seat frame or cushion. The hinge allows for mechanical adjustment of the tension used in the flex of the back frame assembly allowing a softer or firmer “ride” depending on the user&#39;s preference. An optional spring-lock spring mechanism provides a means to the user to fix the back position in the normal sitting position by simply moving a lever. The design as a whole can operatively connect standard seat frame units with easily interchangeable back frame and arm rest profiles and also different spring hinge assemblies, which improves adaptability to different styles and configuration of finished furniture with improved performance and reduced number of variable parts. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0004]      FIG. 1  is an isometric view of a spring back hinge assembly. 
           [0005]      FIG. 2A  is an exploded view of the spring back hinge and backrest assembly with optional spring lock mechanism. 
           [0006]      FIG. 2B  is a perspective view illustrating an alternative embodiment of seat back. 
           [0007]      FIG. 2C  is a perspective view illustrating an alternative embodiment of seat back. 
           [0008]      FIG. 2D  is a perspective view illustrating an alternative embodiment of seat back. 
           [0009]      FIG. 3  is an isometric view of another embodiment of a seat assembly with a spring back hinge and without a lock mechanism. 
           [0010]      FIG. 3A  is a detailed isometric view of the installed spring back hinge without a lock mechanism. 
           [0011]      FIG. 4  is an isometric view of a third embodiment of a seat assembly with a spring back hinge and a lock mechanism in the unlocked position. 
           [0012]      FIG. 4A  is a detailed isometric view of the installed spring back hinge with a lock mechanism in the unlocked position. 
           [0013]      FIG. 5  is an isometric view of a fourth embodiment of a seat assembly with a spring back hinge and a lock mechanism in the locked position. 
           [0014]      FIG. 5A  is a detailed isometric view of the installed spring back hinge with a lock mechanism in the locked position. 
           [0015]      FIG. 6  is an isometric view of a fifth embodiment of a seat assembly with a spring back hinge mounted to a chair frame. 
           [0016]      FIG. 6A  is a detailed isometric view of the installed spring back hinge mounted to a chair frame. 
           [0017]      FIG. 7  is a perspective view of the installed spring back hinge of  FIGS. 6 and 6A . 
           [0018]      FIG. 8  is a perspective view of the installed spring back hinge of  FIGS. 6 and 6A  from an angle rotated from that of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The foregoing drawings and the description below represent a system using a left and right spring back hinge with or without lock. For single side systems, one side would be replaced with a pivoting hinge system. 
         [0020]    Referring now to  FIGS. 1 and 2  a spring back hinge assembly  10  is provided. The assembly  10  has a base plate  12  and a hinge plate  14 . The base plate  12  has a locking pin  16  and lock rod clearance slot  18 . Locking pin  16  allows for the base plate  12  and hinge plate  14  to be locked in a fixed position when an optional spring lock assembly  46  is installed. Locking pin  16  may also act as a motion limit pin which limits rearward travel of the back frame assembly. The base plate  12  contains a spring mounting plate  20 . In a preferred embodiment, the spring mounting plate  20  is formed from a bend  22  in the base plate  12 . The base plate  12  may also contain bends, such as bends  24 , in a preferred embodiment, to conform to the design of a chair frame. Additionally, in a preferred embodiment, the base plate  12  has mounting holes  26  and a recess  28  to allow for mounting to a chair frame. The hinge plate  14  may also contain a spring return plate  14 A. In several embodiments, the spring return plate  14 A is formed from a bend  14 B in hinge plate  14 . Lock rod clearance slot  18  may receive a lock rod  48  when lock assembly  46  is installed. Because of the obround shape of slot  18 , engagement of lock assembly  46  moves the ends of rod  48  in slot  18  to lock seat back  112 . 
         [0021]    In  FIG. 1 , hinge plate  14  is movably connected to base plate  12  with a fastener  30  (for example a bolt, rivet, pin, etc.) to permit rotation of plate  14  relative to plate  12 . The fastener  30  is received through a hole in the hinge plate  14  and hole in the base plate  12 . The adjustable tension bolt  32  is fixedly received through a hole in the spring mounting plate  20  and slidably received through a hole in the spring return plate  14 A. A spring  34  surrounds the adjustable tension bolt  32 , which can then be adjusted to increase or decrease the tension on the hinge plate  14 . For example, when the bolt  32  is tightened, the spring  34  is compressed, thus increasing the tension in the spring  34  resulting in increased tension in the hinge plate  14  in relation to the base plate  12 . When the tension in the spring  34  is increased, more pressure is required from a user to “rock” or recline in the chair or seat. 
         [0022]    Hinge plate  14  has a mounting plate  36  with mounting holes  38  to be mounted to a backrest frame  112 . In a preferred embodiment, the mounting plate  36  is formed from a bend  40  in the hinge plate  14 . The hinge plate  14  may also contain bends, such as bends  42 , in a preferred embodiment to conform to the design of a chair frame or backrest frame  112 . Hinge plate  14  also contains a lock mechanism receiving hole  44  for receiving a lock assembly  46 . 
         [0023]    Referring now to  FIG. 2 , an exploded view of the assembly  10  and how it connects with a backrest frame  112  is provided. In the provided embodiment, the backrest frame  112  is a substantially rectangular structure with sinuous springs  114  extending between a frame cross member  116 . In a preferred embodiment, the sinuous springs  114  are generally parallel to the chair base frame  110  (shown in  FIGS. 3-5   a ), although other types of springs may provide equivalent functionality.  FIG. 2  preferred embodiment shows the lock assembly  46  having a lock rod  48  locking plate  52  fixed to lock rod  48  and having a lever handle  50  and locking arm  54  and locking cam  56 . Alternately locking plate  52  and handle  50  can be located on one side of lock rod  48  only. Backrest frame  112  has mounting holes for receiving mounting bolts  118 . Mounting bolts  118  are received by the mounting holes  38  of the mounting plate  36 , thereby fixing the hinge plate  14  to the backrest frame  112 . Additionally, mounting bolts  118  are received by mounting holes  120  in spring steel straps  122  with optional spring lock  46 . Spring steel straps  122  are ‘L’ shaped and apply pressure to the lock rod  48  to maintain a locked or unlocked position of the locking levers  50 .  FIG. 2A ,  FIG. 2B  and  FIG. 2C  illustrate variations in backrest frame  112  outside shape, which may be used as alternatives to provide selected appearance to a finished, upholstered chair or seat. The independent operation of spring assembly  10  permits this adaptation, while keeping the other components the same. 
         [0024]    Referring now to  FIG. 3 , an exemplary embodiment of a chair or seat is shown with spring hinge assembly  10 . The chair or seat is made up of legs  102  and  104 , armrests  106 , chair base frame  110 , and backrest frame  112 . Other chair and seating designs, for example different types of bases, number of legs, or types of backrests, movable chairs, or mounted seats, in a variety of uses, such as furniture in or associated with buildings or outdoors, or seating in vehicles, have been considered. In one embodiment, two spring hinge assemblies  10  are attached via the base plates  12  of the assemblies  10  to the base frame  110 , and a backrest frame  112  is mounted to the hinge plates  14  of the assemblies  10 . Another embodiment is for the spring hinge  10  to be attached to arm assembly  136 . 
         [0025]    Chair base frame  110  as shown is a leg assembly which can be individually attached to a seat frame unit consisting of side rails and front and rear frame end members  132 , without or without springs. In this embodiment, sinuous springs  134  are stretched between the frame end members  132 , although other spring types could be considered. Also shown in a preferred embodiment are the armrests  106  and rear legs being formed from one continuous member  105 , and with additional side members  130  attached although other commonly known designs are considered. 
         [0026]      FIGS. 3 and 3   a  are shown without an optional lock assembly. Specifically referring to  FIG. 3   a , which is taken from cutout “ 3 A” of  FIG. 3 , the lock assembly receiving hole  44  does not include the lock rod  48  of the lock assembly  46 . 
         [0027]    Referring now to  FIGS. 4 and 4   a , an exemplary embodiment of a chair or seat as shown in  FIG. 3  is provided along with the lock assembly  46 . The spring back hinge assemblies  10  in this embodiment are mounted to the seat frame unit  132 , and the backrest frame  112  is mounted to the assemblies  10  as described above.  FIGS. 4 and 4   a  show the lock assembly  46  in the unlock position. Specifically referring to  FIG. 4   a , which is taken from cutout “ 4 A” of  FIG. 4 , while in the unlock position, the lever handles  52  are in an upward position, and thus locking cam  56  is below locking pin  16  and the locking arms  54  will not contact or engage with the locking pins  16  when a user leans against the backrest frame  112 . Therefore, with the lock assembly  46  in this position, the user can freely “rock” or recline backwards while sitting in the chair, within the mechanical limits of the apparatus. As mentioned above, the spring steel strap  122  provides pressure to the lock rod  48  in order to keep the lock assembly  46  in the unlock (upward) position. Lock assembly is maintained in this position by spring steel straps  122 . Spring steel straps  122  are ‘L’ shaped and apply pressure to the lock rod  48  to maintain a locked or unlocked position of the locking levers  50 . Moving lever handle  52  engages cam and displaces spring strap  122  until the area between cam  56  and arm  54  engages pin  16 , as shown in  FIG. 5  and  FIG. 5A . 
         [0028]    Referring now to  FIGS. 5 and 5   a , an exemplary embodiment of a chair as shown in  FIGS. 3 and 4  is provided with the lock assembly  46  in the lock position. As stated above, in this embodiment the spring back hinge assemblies  10  are mounted to the seat frame  132 , and the backrest frame  112  is mounted to the assemblies  10 . This, therefore, permits mounting and rotation independently of armrests  106  and is particularly well adapted to structures that have different chair frames, such as wooden or arm-less chair frames.  FIGS. 5 and 5   a  show the lock assembly  46  in a locked position. Specifically referring to  FIG. 5   a , which is taken from cutout “ 5 A” of  FIG. 5 , when lever handle  52  is placed in a locked position (such as in a downward position) being moved against spring steel strap  122  and then held in engagement by spring steel strap  122 , locking arm  54  will prevent the backrest frame  112  from rocking by bracing against locking pin  16 . Therefore, when a user leans back against the backrest frame  112 , the locking arm  54  will immediately engage the locking pin  16  and prevent the backrest frame  112  from “rocking” or reclining. 
         [0029]      FIG. 6  and  FIG. 6A  show an embodiment in which the spring hinge  10  is attached to arm assembly  136 . Arm assembly  136  includes a plate or web  138  that interconnects the arm and leg portions into a structural unit. In this embodiment In  FIG. 7  and  FIG. 8  hinge plate  214  is movably connected to base plate  212  with a fastener  230  (for example a bolt, stud, rivet, pin, etc.) which may be adapted to receive an adjustable tension nut  232 . The fastener  230  is fixedly mounted to the base plate  212  and passes through the hinge plate  214  so as to permit the relative motion, as restrained by spring  234 . In particular, fastener  230  passes through the seat back mounting plate flange  220  of plate  214  such as through an aperture. A spring  234  surrounds the fastener  230  and compressed by adjustable tension nut  232 , which can then be adjusted to increase or decrease the tension on the plate  214 . For example, when the nut  232  is tightened, the spring  234  is compressed, thus increasing the tension in the spring  234  resulting in increased tension in the hinge plate  214  in relation to the base plate  212 . When the tension in the spring  234  is increased, more pressure is required from a user to “rock” or recline in the chair. 
         [0030]    Hinge plate  214  has a mounting plate  236  with mounting holes  238  to be fastened mounted to a backrest frame  112 . In a preferred embodiment, the mounting plate  236  is formed by two bends  240  in the hinge plate  214 . Base plate  212  has hole  226  in mounting flange  228  for mounting to plate  138  or such other suitable gusset, flange or structure. Frame  112  mounted to plate  236  rotates around pin  242  to permit movement, which movement compresses spring  234  as frame  112  is moved or rocked by a user of the seating device. This arrangement permits back frame  112  to be mounted and move independently of seat frame unit  132 . 
         [0031]    Also seen in  FIG. 6 , seat frame unit  132  has been preferably been replaced by a double spring function leaf spring and coil spring seat frame unit  250 . Seat frame unit  250  is taught in co-pending application Ser. No. 10-595,330, also published as US Publication No. 2007-0040311 on Feb. 22, 2007, which disclosures are incorporated by reference as if full set forth herein. 
         [0032]    Numerous modifications to the features described and shown are possible. Accordingly the described and illustrated embodiments are to be construed as merely exemplary of the inventive concepts expressed herein.

Technology Classification (CPC): 8