Patent Publication Number: US-6905168-B2

Title: Stackable folding chair

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This is a continuation-in-part of application Ser. No. 10/102,664, filed Mar. 22, 2002, and now U.S. Pat. No. 6,592,182. 

   BACKGROUND OF THE INVENTION 
   The invention relates to an improved folding chair. More particularly, the invention relates to a stackable folding chair having stacking guides and a notch that permit multiple chairs to be stacked on top of each other and maintained in an organized manner. 
   DESCRIPTION OF RELATED ART 
   It is well known that conventional folding chairs provide readily available seating. Typically, such chairs are used as temporary seating arrangements and are easily folded and stored when not in use. For situations involving large audiences, such as when used in arenas, for weddings, and other such events, the large number of folding chairs are usually stacked on top of each other and stored accordingly. Unfortunately, the conventional folding chair suffers from a drawback of being difficult to stack in an organized manner and tend to slide relative to each other when stacked. An attempt to overcome the sliding problem has been to configure containers or carts that are specifically structured to receive and hold the folded chairs in an orderly manner. 
   Attempts have also been made to design and manufacture folding chairs that do not require separate containers and/or carts specifically configured to store the folded chairs. 
   U.S. Pat. No. 5,634,684 to Kojima et al. discloses a typical example of stacked folding chairs wherein a separate brace device is attached to the chair legs so as to engage the brace of a second folded chair in order to stack multiple folded chairs. The Kojima et al. folding chair suffers from the drawback of requiring the brace as an additional component that is attached to chair, which increases the cost of manufacturing each chair and adds a step in stacking the chairs as a result of having to ensure the braces of the stacked chairs engage each other. 
   U.S. Pat. No. 5,738,408 to Wu discloses a stackable folding chair having protrusions integrally formed on a front side of the front legs and a corresponding number of indentations integrally formed on a back side of the same front legs opposite the protrusions. The indentations are configured to receive the protrusions from a second chair. 
   Therefore, when the chairs are folded and positioned adjacent to one another, the protrusions on the front side of the front legs of a first chair fit within the corresponding indentations on the back side of the front legs of the next or second chair. The first and second chairs are thus retained in the stacked arrangement. Furthermore, each protrusion has a first geometric shape occupying a first surface area. Each indentation is multi-leveled to have a first region adjacent an outer surface of the back leg having the same general geometric shape of the protrusion, but occupies a larger surface area. A second, inner region of each indentation is positioned inward of the first region and has the same geometric shape as the protrusion. The second region is dimensioned so the protrusion sits flush within the second region. 
   The indentations are formed to have multi levels so the person stacking the chairs can first locate the protrusion within the first region of the indentation. Because the first region of the indentation is larger than the protrusion, the person stacking the chairs is able to generally position the protrusion of the first chair within the first region of the corresponding indentation on the second chair. After the protrusions of the first chair are positioned within the first regions of the corresponding indentations of the second chair, the person stacking the chairs can position the protrusions within the second region to securely stack the first and second chairs together as the outer edges of the first region act as a boundary. 
   As such, the Wu folding chair suffers from complicated and costly manufacturing methods in order to machine the legs to have the multi leveled indentations capable of receiving the protrusions therein, thereby raising the cost of each chair. Furthermore, the step of aligning the protrusion first with the first region of the indentation and then the second region of the indentation can become rather cumbersome if a large number of chairs is involved in the stacking process. 
   Another example of an attempt to provide a stackable folding chair is disclosed in U.S. Pat. No. 6,099,073 to Bruschi. Bruschi discloses a stackable plastic folding chair having front legs with shaped portions that extend outwardly from opposite sides of an intermediate section to form stop abutments for ends of a back leg of an adjacent folding chair. The seat of the chair is connected to the front legs by pivot pins and is connected to the back legs by pivot pins. The pivot pins connecting the seat to the front legs are only rotatable, whereas the pivot pins connecting the seat to the back legs are slidable in grooves formed along a longitudinal axis of the back legs. The seat also has a transverse housing positioned at the rear of the seat. 
   The transverse housing has a U-shape when seen from a side view and is configured to hook a crosspiece connecting the back legs from below. It is important to note that the transverse housing is not a feature of the Bruschi chair involved in the stacking process. 
   Rather, each front and back leg has a right-angled profile including a larger wing and a smaller wing, respectively, with each large wing being perpendicular to its respective small wing. In the compacted position, the front and back legs are close to each other so as to substantially define side columns having C-shaped profiles. In the compacted position side columns, the large wings of the front legs are next to the small wings of the back legs. Accordingly, first and second shaped portions are provided at upper and lower end sections, respectively, of the front legs to form stop abutments for the first and second ends of the back legs of a second chair in the compacted position that is to be stacked with the first chair in the compacted position. 
   Put simply, Bruschi uses the wings formed by the shaped portions of the front and back legs to facilitate stacking of multiple chairs. The shaped portions require additional materials and manufacturing steps, thereby increasing the amount of time needed to produce each chair as well as the cost of such. 
   U.S. Pat. No. 5,967,605 to Stanfield discloses a folding chair having a stacking device or brace that is sized to be fitted snugly to a cylindrical chair leg. The brace engages the brace of a second chair wherein multiple chairs can be stacked in an orderly manner. The braces require additional materials as they are an additional component that must be added to the standard framework of the chair. The braces therefore require additional manufacturing time and material which result in an increased overall cost of the chair. 
   In the stackable folding chair disclosed in co-pending patent application Ser. No. 10/102,644, stacking guides  34 ,  34  and a stacking notch  41   a  are integrated into the structure of the seat  30  of the chair  1 . As shown in  FIGS. 1-6 , the chair  1  also includes a pair of parallel front legs  11 ,  12  and a pair of parallel back legs  21 ,  22  pivotally connected to the front legs  11 ,  12 . The front legs  11 ,  12  are separated by top, bottom and intermediate crosspieces  15 ,  13 , and  14 , respectively, wherein the top crosspiece  15  forms a back rest. The back legs  21 ,  22  are separated by a top and a bottom crosspiece  24  and  23 , respectively. A seat  30  is rotatably connected to the front legs  11 ,  12  by a rod  31  between the backrest  15  and intermediate crosspiece  14  and slidably connected to the back legs  21 ,  22  by a pair of dowel pins  38 ,  38  that engage dowel slots  29 ,  29  formed on the inner side face of each back leg  21   a ,  22   a.    
   The seat  30  includes a plurality of stacking guides  34 ,  34 , a stacking lip  40   a  integrally formed therein, and a receiving groove  35  that receives the intermediate crosspiece  14  of the main frame  10  when the chair  1  is folded. The stacking guides  34  extend downward and away from a bottom surface  33  of the seat  30  and the stacking lip  40   a  extends in a direction relatively orthogonal to a top surface of the  39  seat  30  to form a substantially right angle shape. The extending direction of the stacking lip  40   a  is substantially opposite the extending direction of the stacking guides  34 ,  34 . 
   The stacking lip  40   a  includes a notch  41   a  that engages the top crosspiece  24  of the back legs when the chair  1  is in the open or in use position and receives a lower back corner  42   b  of a second seat in the closed or folded position, wherein the first and second chairs are orderly stacked together. 
   The intermediate crosspiece  14  of the main frame  10  requires additional material, additional manufacturing time, and increases the overall cost of the chair  1 . Furthermore, the receiving groove  35 , which engages the intermediate crosspiece  14  of the main frame  10 , requires a rather complicated die in which the plastic or resin is injected to form the bottom surface  33  of the seat  30 . Additionally, the presence of the receiving groove  34  can decrease the overall strength of the seat  30 . 
   SUMMARY OF THE INVENTION 
   It is an object of this invention to overcome the above-described drawbacks of the related art. 
   It is also an object of this invention to provide a stackable folding chair having longitudinally extended stacking guides and a stacking notch integrated into the structure of the seat of the chair, wherein the main frame of the chair includes only top and bottom crosspieces separating the legs thereof and the bottom surface of the seat omits the receiving groove, resulting in a seat bottom surface that is relatively smooth, except for the stacking guides extending along and therefrom. 
   It is yet another object of this invention to provide a stackable folding chair having a pair of parallel front legs and a pair of parallel back legs pivotally connected to the front legs. The front legs are separated by top and bottom crosspieces, wherein the top crosspiece forms a back rest. The back legs are separated by a top and a bottom crosspiece. A seat is rotatably connected to the front legs by a rod between the backrest and bottom crosspiece and slidably connected to the back legs by a pair of dowel pins that engage dowel slots formed on the inner side face of each back leg. The seat includes a plurality of longitudinally extended stacking guides and a stacking lip integrally formed therein. The stacking guides extend downward and away from a bottom surface of the seat and the stacking lip extends in a direction relatively orthogonal to a top surface of the seat to form a substantially right angle shape. The extending direction of the stacking lip is substantially opposite the extending direction of the stacking guides. A bottom surface of the seat is relatively uniform and smooth with the exception of the stacking guides extending along and therefrom. The stacking lip includes a notch that engages the top crosspiece of the back legs when the chair is in the open or in use position and receives a lower back corner of a second seat in the closed or folded position, wherein the first and second chairs are orderly stacked together. 
   These and other objects and aspects of the invention will be described in or be apparent from the following description of the preferred embodiment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein: 
       FIG. 1  is a perspective view of a conventional stackable folding chair in the open or in use position; 
       FIG. 2  is a perspective view of the seat of the conventional stackable folding chair shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of two of the conventional stackable folding chairs shown in  FIG. 1  before being stacked together; 
       FIG. 4  is a perspective view of two seats from the conventional chairs stacked together; 
       FIG. 5  is a sectional view of two stacked conventional chairs; 
       FIG. 6  is a perspective view of a folded conventional chair 
       FIG. 7  is a perspective view of the main frame of the conventional chair shown in  FIG. 1 ; 
       FIG. 8  is a perspective view of the main frame of the stackable folding chair according to the present invention; 
       FIG. 9  is a bottom view of the seat of the conventional chair shown in  FIG. 1 ; 
       FIG. 10  is a bottom view of the seat of the stackable folding chair according to the present invention; 
       FIG. 11  is a perspective view of the conventional folding chair in the closed position; 
       FIG. 12  is a perspective view of the stackable folding chair according to the present invention in the closed position; 
       FIG. 13  is a sectional view of two stacked folding chairs according to the present invention; 
       FIG. 14  is a perspective view of the complete stacked folding chairs shown in  FIG. 13 ; and 
       FIG. 15  is a perspective view of the stackable folding chair according to the present invention in the open or in use position. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     FIG. 7  is a perspective view of the main frame  10  of the conventional stackable folding chair  1  shown in  FIGS. 1-6 . The main frame  10  includes a pair of substantially parallel front legs  11  and  12  separated by a bottom crosspiece  13 , an intermediate crosspiece  14 , and a top crosspiece  15 , wherein the top crosspiece  15  forms a backrest.  FIG. 8  is a perspective view of a main frame  110  of a stackable folding chair according to the present invention. As shown in  FIG. 8 , the main frame  110  includes a pair of substantially parallel front legs  111  and  112 , separated by top and bottom crosspieces  115  and  113 , wherein the top crosspiece  115  functions as a backrest. A comparison of the main frame  10  from the conventional chair and the main frame  110  from the stackable folding chair of the present invention reveals the fact that the main frame  110  of the present invention does not include an intermediate crosspiece and therefore requires less material to manufacture, which results in a simpler injection die, requires less time to manufacture, and lowers overall costs. 
   The main frame  110  of the present invention operates with the support frame  20  of the conventional stackable folding chair shown in  FIGS. 1 ,  3 , and  5 - 6 . The support frame includes a pair of substantially parallel back legs  21  and  22  pivotally connected to the front legs  111  and  112  by pivot pins  27 ,  27 . The back legs  21  and  22  are separated by a bottom crosspiece and a top crosspiece,  23  and  24 , respectively. 
   It should be noted that it is preferable that the components of the stackable folding chair according to the present invention are primarily formed using plastic or resin injection molding techniques. However, it is within the scope of this invention to manufacture the components of the chair from any other suitable material, such, as, for example, metal, wood, and the like. 
     FIG. 9  is a bottom view of the seat  30  of the conventional chair, which includes has a substantially rectangular shape body and is pivotally connected to the front legs  11  and  12  by a rod  31  at a location above the intermediate crosspiece  14  and below the pivot pins  27 ,  27  connecting the support frame  20  to the main frame  10 . As shown in  FIGS. 2 ,  4  and  9 , a bottom surface  33  of the seat  30  includes a pair of stacking guides  34  extending away therefrom and a receiving groove  35  that receives the intermediate crosspiece  14  of the main frame  10  when the chair  1  is folded. Furthermore, the rod  31  passes through the seat  30  via through-holes  37 ,  37  disposed intermediate the receiving groove  35  and stacking guide  34 . 
   A stacking lip  40   a  is integrally formed with the seat  30  and extends away from an upper surface  39  of the seat in an orthogonal direction relative thereto to form a substantially right angle shape. The extending direction of the stacking lip  40   a  is substantially opposite relative to the extending direction of the stacking guides  34 , i.e., upward and away from the upper surface  39  of the seat  30 . 
   The stacking lip  40   a  includes a notch  41   a  extending substantially across an entire width W of the seat  30 . The notch  41   a  that engages the top crosspiece  24  of the support frame  20  when the chair  1  is in the open or in use position. Furthermore, the stacking lip  40   a  has vertical height H relative to the upper surface  39  of the seat  30 . The vertical height H of the stacking lip  40   a  is of a length wherein the notch  41   a  of the stacking lip  40   a  extends beyond an outer boundary defined by a rear face of either the front and back legs,  11 , 12  and  21 , 22 , respectively, when the chair is in the folded position. As shown within the circle of  FIG. 4 , the notch  41   a  receives a lower rear corner  42   b  of a second seat when the first and second seats are in the closed or folded position (FIG.  5 ), thereby permitting the first and second chairs to be orderly stacked together. 
   As shown in  FIG. 5 , when multiple chairs are folded to be stacked on top of each other, the stacking guides  34  of the first chair extend toward the second chair. The stacking guides  34  of each chair are designed to prevent the stacked chairs from sliding side to side as indicated by the line S—S when the chairs are stacked vertically, i.e., the support frame and seat of each chair are folded up or closed. Furthermore, the arrangement of the stacking guide  34  in conjunction with the notch  41   a  prevents the stacked chairs from sliding forward and backward relative to each other. 
   The stacking guides  34  extending downward and away from the bottom surface  33  of the seat  30  engage the intermediate crosspiece  14  separating the front legs  11  and  12  of the main frame  10  (FIG.  1 ). Thus, when a downward force is applied to the seat  30 , such as, for example, when a person sits down on the seat when the chair is in the open or in use position, the stacking guides  34  engage the intermediate crosspiece  14  and the notch  41   a  engages the top crosspiece  24 . 
     FIG. 10  is a bottom view of the seat  130  of the stackable folding chair according to the present invention. The seat  130  of the present invention has a substantially rectangular shape body and is pivotally connected to the front legs  111  and  112  by a rod  31  ( FIG. 2 ) in a manner similar to the seat  30  in the conventional chair  1 . Furthermore, the seat  130  of the present invention operates in a similar manner to the seat  30  of the conventional chair  1 . 
   However, a comparison of the seat  30  from the conventional chair and the seat  130  from the stackable folding chair of the present invention reveals the fact that the seat  130  of the of the present invention does not include a receiving groove  35  (FIG.  9 ). The seat  130  of the present invention does not require a receiving groove because the seat of the present invention does not need to engage an intermediate crosspiece since the main frame  110  of the present invention does not provide such a feature. Moreover, the stacking guides  134  are extended in a lengthwise direction that is parallel relative to the surface  133  of the seat  130  so as to overlap or extend beyond the region of the seat  130  that includes the through-holes  137 ,  137 , thereby increasing the overall strength of the seat  130 . 
   As a result, the seat  130  of the present has a relatively uniform and smooth bottom surface  133  except for the stacking guides  134  extending along and away therefrom in a manner similar to the stacking guides  34  of the conventional chair. The uniform and smooth bottom  133  of the seat  130  of the present invention, see  FIG. 10 , allows the die from which the seat  130  is manufactured by resin or plastic injection molding to be simplified. As a result, the manufacturing labor and time, as well as overall costs, is substantially reduced. Furthermore, the possibility for imperfections to arise in the injection molded seat  130  of the present invention are greatly reduced. Additionally, the absence of a receiving groove in conjunction with extending the stacking guides  134  in a lengthwise direction that is parallel relative to the bottom surface  133  increases the overall strength of the seat  130 . As will be explained below in further detail, the seat  130  of the present invention also has a pair of dowel pins  138  extending therefrom to connect the seat  130  of the present invention to the slots  29 ,  29  in the back legs  21 ,  22  of the support frame  20 , as well as a stacking lip  140   a  with a notch  141   a  that function similar to the dowel pins  38 ,  38 , notch  40   a , and lip  41   a  of the conventional chair. 
   It should be noted that it is within the scope of this invention to have the rod  31  formed either from plastic or resin injection molding techniques, metal, wood or any other suitable material. 
   It should be noted that the seat  130  of the present invention is shown in the drawing figures as having an opening  132  defined therein merely for explanatory purposes as well as to better illustrate the spatial and working relationship of the features of the chair. It is within the scope of this invention to have a seat  130  with a solid body, i.e., no opening, or even a covering element (not shown) that covers or fills the opening  132 . 
   More particularly and as shown in  FIG. 10 , the bottom surface  133  of the seat  130  of the present invention includes a pair of stacking guides  134  extending away therefrom. The stacking lip  140   a  is integrally formed with the seat  130  and extends away from an upper surface  139  of the seat in an orthogonal direction relative thereto to form a substantially right angle shape. The extending direction of the stacking lip  140   a  is substantially opposite relative to the extending direction of the stacking guides  134 , i.e., upward and away from the upper surface  139  of the seat  130 . 
   The stacking lip  140   a  on the seat  130  of the present invention includes a notch  141   a  extending substantially across an entire width W (see  FIG. 2 ) of the seat  130 . The notch  141   a  that engages the top crosspiece  24  of the support frame  20  when the chair is in the open or in use position. Furthermore, the stacking lip  140   a  has vertical height H (see  FIG. 2 ) relative to the upper surface  139  of the seat  130 . The vertical height H of the stacking lip  140   a  is of a length wherein the notch  141   a  of the stacking lip  140   a  extends beyond an outer boundary defined by a rear face of either the front and back legs,  111 ,  112  and  21 ,  22 , respectively, when the chair is in the folded position. 
   As exemplarily shown within the circle of  FIG. 4 , the notch  141   a  of the seat  130  of the present invention can also receive a lower rear corner  42   b  of a second seat when the first and second seats are in the closed or folded position (FIG.  5 ), thereby permitting the first and second chairs to be orderly stacked together. 
   As exemplarily shown in  FIG. 5 , when multiple chairs are folded to be stacked on top of each other, the stacking guides  134  of the seat  130  of the present invention extend toward a second chair. As such, the stacking guides  134  of each chair are designed to prevent the stacked chairs from sliding side to side as indicated by the line S—S when the chairs are stacked vertically, i.e., the support frame and seat of each chair are folded up or closed. Furthermore, the arrangement of the stacking guides  134  in conjunction with the notch  141   a  prevents the stacked chairs from sliding forward and backward relative to each other. 
   When a downward force is applied to the seat  130  of the present invention, such as, for example, when a person sits down on the seat when the chair is in the open or in use position, the notch  141   a  engages the top crosspiece  24  of the support frame  20 , which prevents the back legs  21  and  22  from separating away from the front legs  111  and  112 . 
   The chair is used as follows. 
   When the chair is in the closed or folded position as shown in  FIG. 12 , the chair is ready to be stacked onto other such chairs. Furthermore, the support frame  20  of the chair rotates toward the main frame  110  wherein outer side surfaces of the back legs  21  and  22  of the support frame  20  abut inner side surface of the front legs  111  and  112  of the main frame  110 . Additionally, a front portion of the seat  130  is proximate the backrest  115  of the main support  110  while the rear portion of the seat having the stacking lip  140   a  is located between the rod  31  of the seat  130  and the lower crosspiece  113  of the main support  110 . 
   As shown in  FIG. 11 , the conventional chair  1  requires the receiving groove  35  to receive the intermediate crosspiece  14  of the conventional chair  1 . 
   The chair of the present invention does not require such an action as the main support  110  does not include such an intermediate crosspiece and the seat  130  does not have such a receiving groove. 
   Therefore, when viewed from the side of the folded chair, the notch  141   a  of the stacking lip  140   a  extends beyond an outer boundary defined by a rear face of either the front and back legs,  111 ,  112  and  21 ,  22 , respectively. As such, the notch  141   a  is able to receive a lower rear corner  42   b  of a second seat when the first and second seats are in the closed or folded position (FIGS.  13  and  14 ), thereby permitting the first and second chairs to be orderly stacked together. Furthermore, the stacking guides  134  of each chair prevent the stacked chairs from sliding side to side relative to each other. 
   Accordingly, an orderly and manageable stacking of multiple folding chairs is obtained. 
   To place the folded chair in the open or in use position (FIG.  15 ), the front portion of the seat  130  is rotated around rod  131  outwardly in a direction away from the abutting front and back legs  111 ,  112  and  21 ,  22 , respectively. Simultaneously, the dowel pins  138  slide along the substantially linear dowel slots  29  formed in the rear legs  21 , and  22  in an upward direction relative to the backrest  115 . The sliding motion of the dowel pins  138  within the dowel slots  29  forces the rear legs  21 ,  22  of the support frame  20  to rotate around pins  27  and away from the front legs  111 ,  112  of the main frame  110 . At the moment the dowel pins  138  reach the top of the dowel slots  29 , the notch  141   a  of the stacking lip  140   a  engages the top crosspiece  24  of the support frame  20 . 
   While the invention has been described in conjunction with the preferred embodiment thereof, it is evident that many alternatives, modifications and variations may be apparent to those skilled in the art. For example, the stacking guides may be configured to have any suitable geometric configuration, such as, for example, circular, rectangular, trapezoidal, triangular, rhomboidal, oval, square, pentagonal, octagonal, parabolic, hyperbolic, elliptical, conical, and the like. Accordingly, the specific embodiment of the invention as set forth herein is intended merely to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as set forth in the following claims.