Patent Abstract:
A stretching structure of a stretching material in a chair in which the ratio of the rear frame of a backrest to the outline of the chair is small, design is smart, weight is reduced, the number of parts is reduced, and assemblability is improved and the backrest of the chair. In the chair having the backrest formed by stretching the stretching material on the front surface of the rear frame, the rear frame comprises a front frame to which the peripheral edge part of the stretching material is fixed and an upper reinforcement frame rod. The laterally facing upper reinforcement frame rod is connected at its both ends to both ends of the laterally facing upper frame rod at the top of the front frame with the center part of the upper reinforcement frame rod separated backward from the upper frame rod.

Full Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a chair and the structure for stretching a mesh over the backrest, a seat, a headrest etc. of the chair. 
       BACKGROUND OF THE INVENTION 
       [0002]    U.S. Pat. No. 6,386,634B1 discloses the backrest structure of a chair and the stretching structure of a mesh in the backrest in which edge material is mounted by molding around the mesh to which tension is already applied, the edge material engaging in grooves in a front surface of a back frame to apply mesh over the front surface of the back frame. 
         [0003]    JP2004-49685A discloses that an engagement piece mounted to the periphery of a mesh engages on a peripheral groove on the rear surface of a back frame, said engagement piece being pressed into the groove by the binding frame mounted to the rear surface of the back frame to apply tension to the mesh over the upper surface of the back frame. 
         [0004]    A hanger for having clothes of a sitting person is mounted to the backrest of a chair in JP6-45553U, JP2004-159745A, JP9-10189U, JP11-155690A and JP5-7179U. 
       Problems to be Solved by the Invention 
       [0005]    However, U.S. Pat. No. 6,386,634B1 discloses that it is necessary to take the width of the back frame to prevent flexure of the back frame by force applied to the mesh when the user sits down, a groove which engages with the edge material around the mesh being formed on the front surface of the back frame so that the periphery of the back frame is exposed from the mesh. The back frame greatly occupying the appearance of the chair causes bad appearance in design. 
         [0006]    In JP2004-49685A, when a user sits down on the chair, flexing of the back frame against the force applied to the mesh is prevented by both the back frame and binding frame. Thus, the back frame covered with the mesh and binding frame not covered with the mesh are overlapped and exposed to the outside, which does not produce good appearance in design as well as heavy weight, a lot of the parts, a lot of time for assembling and high cost. 
         [0007]    In JP6-45553U and JP2004-159745A, the support rod for supporting the hanger body is directly mounted in the middle of the rear surface of the backrest. It cannot be applied to a chair in which mesh is applied to the back frame. And a special device is required so that the mounting parts do not project from the front surface of the backrest when the support rod is directly attached to the middle of the rear surface of the backrest. 
         [0008]    In JP9-10189U, JP11-155690A and JP5-7179U, the support rod is mounted to the transverse rod at the lower part of the rear of the backrest or support post standing from the lower part thereby increasing the length of the support rod. When the chair is pulled with the hunger body, the hanger is likely to be broken. 
         [0009]    In view of the above disadvantages in the prior art, it is objects of the present invention to solve the problems below: 
         [0010]    (A) To provide a chair with the backrest structure in which the ratio of the back frame is small with respect to the appearance of the chair, having good design, light weight, reduction in the number of parts and improvement in assembling. 
         [0011]    (B) To provide a chair with a hanger in which the hanger is easily mounted to the backrest to allow parts for mounting the hanger not to project from the front surface of the backrest, preventing the hanger from being damaged and providing good appearance. 
         [0012]    (C) To provide the structure for a mesh over the backrest of a chair in which the ratio of a frame to appearance of the chair is small to provide good appearance, light weight, reduction in the number of parts and improvement in assembling. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a front elevational view of the first embodiment of a chair according to the present invention; 
           [0014]      FIG. 2  is a side elevational view thereof; 
           [0015]      FIG. 3  is a rear perspective view thereof; 
           [0016]      FIG. 4  is a front perspective view of the backrest; 
           [0017]      FIG. 5  is a sectional view taken along the line V-V in  FIG. 4 ; 
           [0018]      FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 4 ; 
           [0019]      FIG. 7  is an enlarged perspective view of the part VII in  FIG. 4 ; 
           [0020]      FIG. 8  is a side view of the second embodiment of a chair with a hanger according to the present invention; 
           [0021]      FIG. 9  is an enlarged rear perspective view of main part of the chair in  FIG. 8 ; 
           [0022]      FIG. 10  is a rear enlarged exploded perspective view of the chair in  FIG. 8 ; 
           [0023]      FIG. 11  is a front enlarged exploded perspective view thereof; 
           [0024]      FIG. 12  is an enlarged sectional view taken along the line XII-XII in  FIG. 9 ; and 
           [0025]      FIG. 13  is an enlarged sectional view taken along the line XIII-XIII in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]      FIGS. 1-7  show the first embodiment of the present invention. 
         [0027]    The present application is applied to the structure of the backrest of the chair and the structure of mesh in the backrest. 
         [0028]    As shown in  FIGS. 1 and 2 , a reclining chair  1  comprises a leg  4  comprising five leg rods  3  each of which has a caster  2  at the end. At the center of the leg  4 , a telescopic leg post  6  which comprises a gas spring  5  stands. At the upper end of the leg post  6 , a rear part of a support base  7  is fixed. 
         [0029]    The support base  7  comprises a hollow rhombus-like box which opens at an upper front part, and arms  8 , 8  are integrally formed from each side of the front part of the support base  7 . 
         [0030]    A hexagonal pivot  9  passes through the support base  7  in the middle. At each end of the pivot  9  extending from the support base  7 , a tubular portion  11   a  fits. The tubular portions  11   a  are provided at the lower front ends of a pair of backrest support rods  11 , 11  that support a backrest  10 . The backrest  10 , the backrest support rods  11 , 11  and the backrest  10  are rotated around the pivot  9  with respect to the support base  7 . 
         [0031]    Inside the support base  7 , there are provided a rubber torsion unit for promoting the pivot  8  in an anticlockwise direction and a promoting-force adjusting device (not shown). In the middle of the front lower surface of the support base  7 , there is a gas spring unit  13  for assisting promoting force of the rubber torsion unit in connection with the rubber torsion unit to form a force-promoting unit to stand the backrest  10 . 
         [0032]    Short arms  12 , 12  project from the backrest support rods  11 , 11  at the back of the pivot  9 . At the upper ends of the arms  12 , 12 , a pair of seat-supporting frames  15 , 15  which support each side of a seat  14  are connected at the rear ends with a shaft  16 . 
         [0033]    The backrest  10  will be described with respect to  FIGS. 3-7 . 
         [0034]    In  FIG. 3 , a back frame  17  of the backrest  10  comprises a rectangular synthetic-resin front face frame  18 . The front face frame  18  comprises an upper frame rod  18   a , a lower frame rod  18   b , a left-side frame rod  18   c  and a right-side frame rod  18   d . The rods  18   b , 18   d  are wider than the rods  18   a , 18   b . A mesh is held on the rods  18   a , 18   b , 18   c , 18   d.    
         [0035]    In  FIGS. 4 and 5 , a pair of grooves  19 , 20  is formed longitudinally on the outer side surfaces of the right and left side frame rods  18   c , 18   d.    
         [0036]    In  FIG. 6 , a groove  21  is horizontally formed along the lower edge of the front surface of the upper frame rod  18   a , and a groove  22  is horizontally formed along the upper edge of the front surface of the lower frame rod  18   b.    
         [0037]    A surface  21   a  between the lower edge of the front surface of the upper frame rod  18   a  and the groove  21  and a surface  22   a  between the upper edge of the front surface of the lower frame rod  18   b  and the groove  22  are grooved by thickness of an outward portion  25   b  of an edge piece  25 . When the edge piece  25  engages with a corner between the lower surface and the front surface of the upper frame rod  18   a  and the front surface and with a corner between the upper surface and the front surface of the lower frame rod  18   b , the end face of each of the edge piece  25  is coplanar with the front surfaces of the upper frame rod  18   a  and the lower frame rod  18   b.    
         [0038]    A mesh  23  may be preferably net-like or mesh-like material knitted or woven from high-tension plastic or other elastic fibers, or may be woven fabric, synthetic resin sheet or porous sheet. Synthetic resin edge pieces  24 , 24  which engage in a pair of grooves  19 , 20  are fixed in the left and right side edges of the mesh  23  by molding. The synthetic-resin edge pieces  25 , 25  which has a hook-like portions  25   d , 25   d  and engage in the grooves  21 , 22  are fixed in the upper and lower edges by molding. 
         [0039]    The edge piece  25  comprises a base  25   a , the outward portion  25   b , and a turning portion  25   c  which turns in parallel with the base  25   a  from the end of the outward portion  25   b . The base  25   a  and the outward portion  25   b  constitute the hook-like portion  25   d.    
         [0040]    The size of the mesh  23  mounted to the edge pieces  24 , 24 , 25 , 25  is formerly determined to apply a suitable tension to the mesh  23  when the edge pieces  24 , 24 , 25 , 25  engage in the grooves  19 , 20  or the grooves  21 , 22 . 
         [0041]    In  FIGS. 4-7 , the right and left edge pieces  24 , 24  of the mesh  23  engage in the grooves  19 , 20  of the right and left side frame rods  18   c , 18   d . The upper and lower ends of the mesh  23  are wound from the front surface to the rear surface around the upper and lower surfaces of the upper and lower frame rods  18   a , 18   b . The hook-like portions  25   d , 25   d  of the upper and lower edge pieces  25 , 25  engage on the corner between the lower surface and the front surface, and the corner between the upper surface and the front surface. The turning portions  25   c , 25   c  of the upper and lower edge pieces  25 , 25  engage in the upper and lower grooves  21 , 22 , so that the mesh  23  is stretched over the entire front surface of the front face frame  18  tensionally. 
         [0042]    Thus, the front surface of the front face frame  18  or the front surface of the back frame  17  is entirely covered with the mesh  23 . So the back frame  17  is not so occupied in the appearance of the chair, so that good impression is given in design. 
         [0043]    In  FIGS. 3 and 6 , to each side end of the upper frame rod  18   a  of the front face frame  18 , an arcuate upper reinforcement rod  26  is joined so that the middle of the rod  26  is spaced apart from the upper frame rod  18   a . The upper reinforcement rod  26  and the upper frame rod  18   a  is like crescent. 
         [0044]    The upper reinforcement rod  26  keeps strength of the upper part of the back frame  17  together with the back frame  17 . When a user is reclined on the backrest  10 , it is allowed for the upper frame rod  18   a  to be slightly flexed elastically. 
         [0045]    The upper reinforcement rod  26  is spaced apart from the upper frame rod  18   a . Thus, without hindering attachment of the mesh  23 , a headrest  27  as shown by dotted lines in  FIG. 4  and an optional member such as a hanger for clothes in  FIG. 8  and so on are detachably mounted. 
         [0046]    The upper reinforcement rod  26  is also used with a hand when the chair is moved. 
         [0047]    In  FIGS. 3 ,  6  and  7 , to the lower ends of the right and left side frame rods  18   c , 18   d  of the front face frame  18 , both ends of the lower reinforcement rod  28  are coupled. The middle of the lower frame rod  18   b  is spaced forward of the lower reinforcement rod  28 , but each end thereof is fastened to each end of the lower reinforcement rod  28  with a screw  29 . 
         [0048]    The lower end of the mesh  23  is wound around the lower frame rod  18   b  after the lower frame rod  18   b  is fastened to the front surface of the lower reinforcement rod  28 . A folding portion  25   c  of the lower edge piece  25  is engaged in the groove  22  of the lower frame rod  18   b , so that the mesh  23  is mounted to the lower frame rod  18   b.    
         [0049]    When the chair is scrapped, a tool such as a screwdriver (not shown) is stuck through the mesh  23  and engaged with a head of the screw  29  which is loosened, so that the lower frame rod  18   b  is removed from the lower reinforcement rod  28 . Thereafter, the upper edge of the mesh  23  and the right and left side edges are removed from the upper frame rod  18   a  and the right and left side frame rods  18   c , 18   d  with the edge members  25 , 24 , 24 . The mesh  23  is separately removed from the back frame  17  and replaced with a new one. 
         [0050]    When the chair is moved and hit with another chair, the lower frame rod  18   b  is protected by the lower reinforcement rod  28 , so that the lower ends of the lower frame rod  18   b  and the mesh  23  are prevented from being damaged. 
         [0051]      FIGS. 8-13  show the second embodiment in which a hanger is mounted to the chair in the first embodiment of the present invention. The basic structure of the chair is similar to the first embodiment, and the same numerals are allotted to the same members. Description thereof is omitted. 
         [0052]    A chair  30  with a hanger in the second embodiment of the invention comprises a hanger  31  that moves up and down behind the backrest  10 . 
         [0053]    The hanger  31  comprises a hanger body  32  on which a suit can be hung; and a pair of support rods  33 , 34  which support the body  32 . The support rods  33 , 34  are mounted on the backrest  10  with a mounting member  35  and a screw seat piece  36  by a screws  37 . 
         [0054]    The backrest  10  comprises the back frame  17  in which the mesh  23  in  FIGS. 1-7  is stretched over the front face frame  18 . The middle of the hanger  31  is spaced apart from the upper frame rod  18   a  of the front face frame  18 , and each end of the hanger  31  is mounted to the middle of the upper reinforcement rod  26  connected to the upper frame rod  18   a.    
         [0055]    A pair of support rods  33 , 34  comprises parallel vertical rod portions  33   a , 34   a ; extending rod portions  33   b , 34   b  inclined upward of the vertical rod portions  33   a , 34   a ; and connecting portions  33   c , 34   c  curved downward of the vertical rod portions  33   a , 34   a . The support rods  33 , 34  are connected at inner ends of the connecting portions  33   c , 34   c.    
         [0056]    The upper ends of the extending rod portions  33   b , 34   b  are plain. The extending rod portions  33   b , 34   b  are mounted to the right and left ends of the hanger body  32  with screws (not shown), so that the support rods  33 , 34  are fixed to the hanger body  32 . 
         [0057]    The extending rod portions  33   b , 34   b  of the support rods  33 , 34  are curved forward. So the hanger body  32  is positioned in front of the rear end of the upper reinforcement rod  26 . 
         [0058]      FIGS. 12 and 13  are enlarged sectional views taken along the line XII-XII and XIII-XIII in  FIG. 9 . 
         [0059]    In  FIGS. 9-12 , plain portions  40 , 41  are formed on opposite surfaces  38 , 39  of the vertical rod portions  33   a , 34   a  of the right and left support rods  33 , 34 . 
         [0060]    A mounting member  35  comprises a thick rectangular plate. The right and left ends  42 , 42  are formed in size such that the mounting member  35  can engage in the plain portions  40 , 41  of the vertical rod portions  33   a , 34   a  of the right and left support rods  33 , 34 . 
         [0061]    On the inner side edges of the plain portions  40 , 41 , vertical projections  43 , 44  are provided in parallel with each other. 
         [0062]    The projections  43 , 44  engage in engagement grooves  45 , 45  on the front surface of the mounting member  35  so that the support rods  33 , 34  slidably move with respect to the mounting member  35 . 
         [0063]    In  FIGS. 11 and 12 , vertical forward projections  46 , 46  are provided on the front surface of the vertical rod portions  33   a , 34   a  of the right and left support rods  33 , 34 . On the rear surface of the upper reinforcement rod  26  of the backrest  10 , vertical engagement grooves  47 , 47  are provided to engage with the forward projections  46 , 46 . 
         [0064]    Through holes  48 , 48  are formed in the mounting member  35 , and through holes  49 , 49  are formed in the upper reinforcement rod  26 . Blind bores  50 , 50  are formed in the rear surface of a screw seat piece  36  at a position corresponding to the through holes  48 , 48 . 
         [0065]    The hanger  31  will be mounted to the upper reinforcement rod  26  below. 
         [0066]    The right and left support rods  33 , 34  having the hanger body  32  at the upper end contacts the upper reinforcement rod  26  to allow the forward projections  46 , 46  of the vertical rods  33   a , 34   a  of the support rods  33 , 34  to engage in the engagement grooves  47 , 47  on the rear surface of the screw seat piece  26 , thereby positioning the support rods  33 , 34 . 
         [0067]    Then, the right and left ends of the mounting member  35  engage in the plain portions  40 , 41  of the vertical rod portions  33   a , 34   a  of the right and left support rods  33 , 34 . In the engagement grooves  45 , 45  on the front surface of the mounting member  35 , the projections  43 , 44  of the plain portions  40 , 41  of the vertical rod portions  33   a , 34   a  engage, and the mounting member  35  is positioned between the right and left vertical rod portions  33   a  and  34   a.    
         [0068]    Then, the screw seat piece  36  contacts the front surface of the upper reinforcement rod  26 . While the support rods  33 , 34  are put between the upper reinforcement rod  26  and the mounting member  35 , the upper reinforcement rod  26  is held between the mounting member  35  and the screw seat piece  36 . The screws  37 , 37  pass into the blind bores  50  of the screw seat piece  36  through the through holes  48 , 49 , so that the hanger  31  is mounted to move up and down with suitable resistance behind the backrest. 
         [0069]    An engagement bore  52  for mounting a cover member  51  is formed in the middle of the mounting member  35 . An inward projection  53  is provided on a rear edge of the engagement bore  52 . The cover member  51  comprises a thin elongate plate and has in the middle an engagement claw  54  which is engagable with the inward projection  53  of the engagement bore  52 . 
         [0070]    On the rear surface of the mounting member  35 , there is formed a recess  55  which engages with the cover member  51 . The engagement claw  54  of the cover member  51  is put in the engagement bore  52  of the mounting member  35  to allow the claw  54  to engage on the inward projection  53 . The entire cover member  51  engages in the recess  55 , so that the cover member  51  is mounted to the mounting member  35 . 
         [0071]    The cover member  51  is also used as nameplate. 
         [0072]    The hanger  31  is slidable up and down. When a suit is hung at an upper limit where the hanger slides, the hanger  31  moves down owing to the weight of the suit and the lower end of the suit contacts a floor, so that the suit is likely to become dirty. 
         [0073]    For prevention, in  FIGS. 10 and 12 , a plurality of small rearward projections  56   a , 56   b  are provided on the vertical rod portions  33   a , 34   a . and an engagement groove  57  which is elastically engagable with the small projections  56   a , 56   b  are provided in  FIGS. 11 and 12 . Thus, at a plurality of vertical positions where the small projections  56   a , 56   b  elastically engage in the engagement groove  57 , the hanger can be held against a certain load. 
         [0074]    By tightening the screw  37 , the support rods  33 , 34  may be held between the upper reinforcement rod  26  and the mounting member  35 . To change a height of the hanger  31 , the screw  37  is loosened to allow the support rods  33 , 34  to move up and down. Thereafter, the screw  37  is tightened again to allow the hanger  31  to be held at a desired height. 
         [0075]    Various modifications of the present invention may be possible without departing from the scope of claims. 
         [0076]    For example, in the foregoing embodiment, the upper reinforcement rod  26  and the lower reinforcement rod  28  are mounted on the rear surface of the upper and lower frame rods  18   a , 18   b . But the upper reinforcement rod  26  or the lower reinforcement rod  28  may be omitted. 
         [0077]    In the foregoing embodiments, the present invention is applied to the stretching structure of the mesh  23  of the backrest  10  of the chair, but may be applied to a seat of a chair or a headrest. 
         [0078]    The edge member  25  is made like a letter L and may engage to a corner between the lower surface and front surface of the upper frame rod  18   a  or lower frame rod  18   b.

Technology Classification (CPC): 0