Abstract:
A seating structure employing a thermoplastic flexor defining the flexibility and stiffness of a seatback is provided. The seating structure may comprise a seat portion for supporting a user, a seatback portion for supporting a user, a frame for supporting the seat portion and the seatback portion, one or more base portions extending at an angle from the seatback portion, and one or more thermoplastic flexors affixed to or within the seatback and base portions of the seating structure. The thermoplastic flexor has certain material characteristics which define and limit the deflection and a rebound of the seatback portion relative to the base portion when under load. The seating structure may further comprise one or more anchors securing the seatback portion, base portion, and thermoplastic flexor to the frame. The seat portion, seatback portion, and base portion may comprise a unibody or multipiece chair shell, and the thermoplastic flexor may be completely enveloped within the shell, or partially disposed behind the shell in a nested mechanical relationship.

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority to U.S. Provisional patent application 62/305,984, entitled “Thermoplastic Chair Flexor,” filed Mar. 9, 2016, incorporated herein by reference in its entirety for all purposes. 
     
    
     FIELD 
       [0002]    The present disclosure relates generally to structures for permitting and limiting movement of a seatback in predetermined manner. 
       BACKGROUND 
       [0003]    Chairs and seatback hinges are generally known. Typically, a chair comprises a seat and a seatback interconnected by some structure. The structure connecting the seat and the seatback can be rigid, such as a metal elbow and flange, or it can provide some flexibility, like a spring. 
         [0004]    Chair users tend to enjoy the ability to recline, as it provides enhanced comfort. However, chair users also enjoy having support for sitting in an upright fashion. Traditionally, providing both advantages; stiffness and flexibility, required the use of one or more metal springs, such as coil springs. 
         [0005]    Using metal components in chairs, such as for a spring connecting a seat to a seatback, poses substantial cost and complexity to the production and sale of a chair. A user may be required to assemble the chair and properly install the spring. If the spring is not properly installed, then the chair will not provide the desired flexibility and stiffness. Additionally, metal springs rust and can make noise while in operation. 
         [0006]    In contrast, using plastic components in chairs has the advantage of reduced cost. However, plastics are often not suitable for structural members, because plastics tend to deflect and deform when placed under stress, and traditionally have poor rebound characteristics. Flexible plastic chairs are often irreparably bent, which fails to deliver the desired support. Also by the same token, stiff plastic chairs are often so hard that a great deal of force is required to induce any deflection, with is uncomfortable and unpleasant for the user. 
         [0007]    Accordingly, a need exists for a plastic chair flexor that provides both the flexibility and stiffness desired by a user. 
       SUMMARY 
       [0008]    The following simplified summary provides a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview, and is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later. 
         [0009]    For example, the following embodiments disclose a seating structure comprising a seat portion for supporting a user, a seatback portion for supporting a user, a frame for supporting the seat portion and the seatback portion, a base portion extending at an angle from the seatback portion an thermoplastic flexor affixed to the seatback and base portions of the seating structure, and wherein the thermoplastic flexor defines and limits the deflection and the rebound of the seatback portion relative to the base portion, and an anchor securing the seatback portion, base portion, and thermoplastic flexor to the frame. 
         [0010]    Moreover, some embodiments disclose a seating structure having one or more thermoplastic flexors comprised of a material, with an ultimate tensile strength characteristic, ranging from 5-117 MPa, an elastic modulus characteristic, E; ranging from 587-20700 MPa; a creep modulus, C, ranging from 1800-2500 MPa when a stress is applied for one hour, and a yield strain, Ys, of greater than 5%. 
         [0011]    Some embodiments identify that the thermoplastic flexor may be a curvilinear elbow comprising an upper extension, a lower extension, and a waist connecting the upper and lower extensions. The thermoplastic flexor may further comprise dimples, apertures, teeth, or other mechanical interlocks throughout the body of the flexor. Differential mechanical interlocking features may optionally be located throughout the upper extension and the waist, as compared to the lower extension. The mechanical interlocking features serve to mechanically secure the thermoplastic flexor internally to the seatback and base portions. 
         [0012]    Some embodiments further disclose a thermoplastic flexor further comprising a gap located transversely across the lower extension, a bridge connecting the two sides of the lower extension separated by the gap, a channel running axially from the bridge to the end of the lower extension, and at least one upright flange running axially from the gap to the end of the lower extension. In such embodiments, the gap creates a plurality of discontinuous cross sectional areas for resisting deflection through lower extension. The gap, bridge, channel, and one or more upright flanges further serve as mechanical interlocking features. Further, in some embodiments, the plurality of discontinuous cross sectional areas in the lower extension comprise (i) an area defined by the channel, (ii) an area defined by the bridge, and (iii) an area defined by the waist. Optionally in some embodiments, the shape of the channel changes throughout the length of the lower extension, and thus creates a differential cross sectional area throughout. For example, the cross sectional area defined by the channel and upright flanges may be greater on one side of the gap and bridge as compared to the cross sectional area formed by the channel and the upright flanges on the other side of the gap and bridge. In one embodiment, the channel terminates at a wall beyond the gap on the far side of the end of the lower extension. The termination of the channel at the wall defines the end of the cross sectional area of the channel, and the beginning of a much greater cross-sectional area of the waist. 
         [0013]    In some embodiments, the thermoplastic flexor may further comprise a first fulcrum formed at a first interface of the lower extension and the anchor, and a second fulcrum formed at a second interface of the lower extension and the anchor. In one embodiment, the second fulcrum is located beneath the channel formed on the far side of the bridge relative to the end of the lower extension. In one embodiment, the first fulcrum may be beneath the bridge, and the second fulcrum may be beneath a transition region between the lower extension and the waist. 
         [0014]    The embodiments disclose how the thermoplastic flexor exerts resistance forces sequentially through the plurality of discontinuous cross sectional areas, when the seatback is under a force. Specifically, the resistance forces are exerted first through the area defined by the channel, and next through the area defined by the bridge, and finally through the area defined by the waist. When the discontinuous cross sectional areas are resisting a force, it triggers the first fulcrum to engage before the second fulcrum engages, and when both fulcrums are engaged, a bending moment is concentrated through the bridge. In one embodiment, the second fulcrum engages before the first fulcrum. The sequential order in which the plurality of fulcrums engage can be defined by variations made to their positioning within the waist, lower extension, and transition region therebetween, as well as variation to the depth and/or angle of the gap, and also through variation to the cross sectional properties of the channel and upright flanges. 
         [0015]    As a result of the discontinuous and sequential resistance imparted by the thermoplastic flexor, the seatback portion deflects according to a variable response characteristic when under load. Typically, the deflection of a seatback is determined by measuring the back deflection at the point of load wherein a load is applied according to an industry standard Sections 5 &amp; 6 of ANSI/BIFMA X5.1-2011. Specifically, this load is applied horizontally to the seatback portion sixteen inches above the seat in the center of the seatback. 
         [0016]    According to an embodiment, the thermoplastic flexor of the present disclosure results in a variable deflection response characteristic of the seatback when placed under load. When plotted on a graph, the variable deflection characteristic comprises a curve approaching a multi-linear response, meaning that deflection increases steadily for a predetermined distance according to a function as force is increased on the seatback, and thereafter deflection increases according to a second function as force is continued to be exerted on the seatback. For example, when a user exerts force on the seatback, the thermoplastic flexor may permit flexibility to allow the seatback to deflect more easily for a predetermined distance, and thereafter, the thermoplastic flexor will decrease flexibility and increase stiffness, permitting the seatback to deflect less easily. Inversely, the seatback may rebound according to a variable response characteristic when load is released. In this respect, the seatback may quickly and/or aggressively rebound initially through a predetermined distance when load is released from a significantly deflected state. This aggressive and/or fast rebounding is associated with enhanced stiffness preferred by a user for supporting upright sitting. Thereafter, the seatback may not rebound as aggressively as load continues to be released from a less deflected state. This non-aggressive and/or slower rebounding is associated with enhanced flexibility as desired by users through moderate ranges of deflection. When plotted on a graph, the variable rebound response characteristic of the seatback may comprise a curve approaching a multi-linear stiffness response when measured relative to the base portion. 
         [0017]    In one embodiment, the seatback portion, base portion, and seat portion of the seating structure of the present disclosure may comprise a unibody thermoplastic shell. The unibody shell may be mounted directly to the chair frame, meaning that the seat, seatback, base, and base portions all connect to the frame together. In one embodiment, the unibody shell may connect to the frame at least through the anchor. 
         [0018]    In one embodiment, optionally, the seatback portion and base portion comprise a multipiece shell. In this example, the seatback portion and base portions are an integrated structure, whereas the seat portion is a separate structure. In this configuration, the structure comprising the seatback portion and base portion is connected to the frame independently from the seat portion. In one embodiment, the structure comprising the seatback portion and base portion is connected to the frame independently from the seat portion at least through the anchor. 
         [0019]    According to one embodiment, the thermoplastic flexor of the seating structure disclosed comprises polyoxymethylene (POM). This material, for example, is offered under the trademark, CELCON® M90, by Ticona Engineering Polymers. 
         [0020]    According to various embodiments, the thermoplastic flexor may be injection molded. The thermoplastic flexor may be secured to the seatback and base portions through mechanical means, such as a screw and nut assembly, clips, pins, glue, or the like. Alternatively, the seatback and base portions may be overmolded relative to the thermoplastic flexor to surround and envelop the thermoplastic flexor. 
         [0021]    According to an embodiment, the thermoplastic flexor may further comprise a stringer to increase the stiffness and/or enhance the rebound characteristics of the seatback. For example, the stringer may be molded within the thermoplastic flexor. 
         [0022]    According to an embodiment, the thermoplastic flexor may not be totally encased within the base portion and seatback. Instead, in this configuration, the thermoplastic flexor remains at least partially disposed within the base portion. In this respect, the thermoplastic flexor is mechanically secured to the back of the seatback and underside of the base portions through mechanical attachment means. By not encasing or overmolding the thermoplastic flexor, less material may be used, and less cost incurred. Rather than requiring the thermoplastic flexor to be manufactured (molded) into the structure of the shell, or requiring the shell to be molded to the flexor, the flexor may be separately sourced and manufactured, and thereafter applied to the chair shell to obtain the desired performance characteristics. 
         [0023]    To the accomplishment of the foregoing and related ends, certain illustrative aspects are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the claimed subject matter may be employed and the claimed subject matter is intended to include all such aspects and their equivalents. Other advantages and novel features may become apparent from the following detailed description when considered in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is an isometric view of a seating structure, disclosing a seat, seatback, two base portions, one on each side of the seat, and a wire-type frame. The thermoplastic flexor of the present invention is not in view because in this embodiment, the chair shell is overmolded. 
           [0025]      FIG. 2  is an exemplary isometric view of a chair shell disconnected from a frame. The seat, seatback, two base portions, and a thermoplastic flexor in each of the base portions are visible in ghost. 
           [0026]      FIG. 3  discloses the chair shell of  FIG. 2 , but the thermoplastic flexors in each of the base portions are not visible. 
           [0027]      FIG. 4  is an exemplary profile view of the thermoplastic flexor of the present disclosure isolated outside the chair shell. The upper extension, waist, and lower extension are visible. A transverse gap and bridge are visible between the waist and the end extension. The upright flange of the axial channel is visible extending from the gap to the end of the lower extension. 
           [0028]      FIG. 5  is an isometric view of the thermoplastic flexor of  FIG. 4 . More clearly visible are the mechanical interlocks, for mechanically securing the flexor to the chair shell, as well as the axial channel extending from the waist to the end of the lower extension, as well as a pair of upright flanges on either side of the axial channel. 
           [0029]      FIG. 6  is an isometric view of the thermoplastic flexor of  FIG. 4  but enveloped by the chair shell. 
           [0030]      FIG. 7  is section-view of the thermoplastic flexor disclosed in  FIG. 6 . More clearly visible are the interlocking teeth mechanically securing the flexor to the chair shell. The interlocking teeth are formed by the mechanical interlocks in the flexor. 
           [0031]      FIG. 8  is a profile view of an embodiment of the thermoplastic flexor encased in the seatback and base and mounted to the anchor of the frame. The frame is not in view. 
           [0032]      FIG. 9  is a magnified view of the encased thermoplastic flexor of  FIG. 8 . The anchor is more clearly visible interconnected with the lower extension 
           [0033]      FIG. 10  is a profile view of an embodiment of the thermoplastic flexor encased in the seatback and base and mounted to the anchor of the frame to show deflection in the seatback and deflection at the fulcrums near the base. The frame is not in view. 
           [0034]      FIG. 11  is a profile view of the seating structure of the current disclosure. The seat, seatback, and base have a continuous semi-annular flange that extends to cover the thermoplastic flexor. 
           [0035]      FIG. 12  is a magnified view of  FIG. 11 , focusing particularly on the bend in the base portion connecting the seat and seatback portions of the seating structure. The continuous semi-annular flange covering the thermoplastic flexor is more clearly visible. 
           [0036]      FIG. 13  is a section view of  FIG. 12 . Exposed is the thermoplastic flexor nested and mechanically secured to the seat, seatback, and base portions of the chair shell. The thermoplastic flexor is further connected to the anchor of the frame. 
           [0037]      FIG. 14  is a front isometric view of an embodiment of the seating structure disclosed herein. The unibody chair shell is seen in ghost, and the chair frame, which has four legs, is connected to the underside of the seat portion. A thermoplastic flexor is seen on each side of the chair, extending from the seatback portion through the base portion to the seat portion and connected to the anchor at the frame. 
           [0038]      FIG. 15  is a rear isometric view of an embodiment of the seating structure disclosed herein. The unibody chair shell is seen in ghost, and the chair frame, which has four legs, is connected to the underside of the seat portion. A thermoplastic flexor is seen on each side of the chair, extending from the seatback portion through the base portion to the seat portion and connected to the anchor at the frame. 
           [0039]      FIG. 16  is a sectional profile view of an embodiment of the disclosed seating structure. The section has been cut through the thermoplastic flexor to expose its mechanical connection and nested relationship to the rear of the seatback portion and the base portion, extending to the underside of the seat portion and connected to an anchor at the frame 
           [0040]      FIG. 17  is a magnified view of  FIG. 16 , focusing particularly on the bend in the base portion. The section has been cut through the thermoplastic flexor to expose its mechanical connection and nested relationship to the rear of the seatback portion and the base portion, extending to the underside of the seat portion. 
           [0041]      FIG. 18  is an isometric view of an embodiment of the seating structure disclosed, including armrests extending from the frame for supporting a user&#39;s arms. The thermoplastic flexor is not in view, as it is obscured by the chair shell. 
           [0042]      FIG. 19  is an isometric view of an embodiment of an alternative frame assembly of the seating structure disclosed, here including a lift comprising a pneumatic cylinder on wheels. The thermoplastic flexor is not in view, as it is obscured by the chair shell. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    The features of the present disclosure may be economically molded by using one or more distinct parts and associated components which, when assembled together, may form the disclosed device regardless of the particular form. Unless defined otherwise, all terms of art, notations and other scientific terms or terminology used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this invention belongs. 
         [0044]    In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art. 
         [0045]    As used herein, “a” or “an” means “at least one” or “one or more.” 
         [0046]    The seating structure employing a thermoplastic flexor can now be better understood turning to the following detailed description. It is to be expressly understood that the illustrated embodiments are set forth as examples and not by way of limitations on the embodiments as ultimately defined in the claims. 
         [0047]    Turning to  FIG. 1 , is an isometric view of a seating structure  101 , disclosing a seat  103 , seatback  105 , two base portions  109 , one on each side of the seat  103 , and a wire-type frame  107 . The thermoplastic flexor  201  of the present invention is not in view because in this embodiment, a chair shell  102  is overmolded around the flexor  201 . In this embodiment, the chair shell  102  is a two-piece shell. One piece  121  comprises the seatback  105  and base  109 , while the second piece comprises the seat  103 . This embodiment also illustrates the potential configuration wherein the thermoplastic flexor  201  is injection molded into the base  109  of one piece of the chair shell  102 . 
         [0048]    Turning to  FIG. 2  is an exemplary isometric view of a two-piece chair shell  102  disconnected from a frame  107  (not seen). The seat  103 , seatback  105 , two base portions  109 , and a thermoplastic flexor  201  in each of the base portions are visible in ghost. As noted in  FIG. 1 , the seatback  105 , two base portions  109  form the upper piece  121  of the two piece shell  102 , and the flexor  201  is located within the base  109  of the upper piece  121 . 
         [0049]    Turning to  FIG. 3  discloses the chair shell  102  of  FIG. 2 , but the thermoplastic flexors  201  in each of the base portions  109  of the upper shell  121  are not visible. This embodiment additionally depicts the configuration where the thermoplastic flexor  201  is optionally injection molded into the base  109  or in which the upper shell  121  is overmolded around the flexor  201 . 
         [0050]    Turning to  FIG. 4  is an exemplary profile view of the thermoplastic flexor  201  of the present disclosure isolated outside the chair shell  102 / 104 . The upper extension  203 , waist  205 , and lower extension  207  are visible. A transverse gap  215  and bridge  213  are visible between the  205  waist and the end extension  207 . The upright flange  211  of the axial channel (see  209  of  FIG. 5 ) is visible extending from the gap  215  to the end of the lower extension  207 . As will be explained in further detail, the flexor  201  interacts with an anchor connected to the frame  107  to form a plurality of fulcrums. The fulcrums may optionally be beneath the bridge  213 , beneath the channel formed on the far side of the bridge (left of  213 ) relative to the end of the lower extension, or beneath a transition region between the lower extension and the waist. 
         [0051]    Turning to  FIG. 5  is an isometric view of the thermoplastic flexor  201 . More clearly visible are the mechanical interlocks  217 , for mechanically securing the flexor  201  to the chair shell  202 / 204 , as well as the axial channel  209  extending from the waist  205  to the end of the lower extension  207 , as well as a pair of upright flanges  211  on either side of the axial channel  209 . In this embodiment, the mechanical interlocks  217  are apertures which extend through the body of the upper extension  203  and waist  205 . This embodiment also shows that the cross-sectional areas of the upright flanges  211  vary along their course of extension, where such variation can result in differential bending and flexing patterns. 
         [0052]    Turning to  FIG. 6  is an isometric view of the thermoplastic flexor  201  but enveloped by the chair shell  202 . The flexor  201  is seen in ghost, either injection molded into the shell  102 , or wherein the shell  102  has been overmolded around the flexor  201  to encase it. In this embodiment, the mechanical interlocks  217  are visible on the rear of the upper extension  203  of the flexor  201 , extending throughout the waist  205 . The bridge  213  and gap  215  are depicted as part of the lower extension  207  within the base  109 . 
         [0053]    Turning to  FIG. 7  is section-view of the thermoplastic flexor  201 . More clearly visible are the mechanical interlocks  217 , in this case, the apertures, when seen in section view, are effectively behaving as in some regions throughout the upper extension  207  and waist  205  as interlocking teeth, mechanically securing the flexor  201  to the chair shell  202 . The upright flanges  211  which define the transverse gap  215  are not in view, because the section cuts through the middle of the axial channel  209 . Thus, only visible in this depiction is the bridge  213 . 
         [0054]    Turning to  FIG. 8  is a profile view of an embodiment of the thermoplastic flexor  201  encased in the seatback  105  and base  109  and mounted to the anchor of the frame  107 . The frame  107  is not in view. 
         [0055]    Turning to  FIG. 9  is a magnified view of the encased thermoplastic flexor  201  of  FIG. 8 . The anchor  213  is more clearly visible interconnected with the lower extension  207 . 
         [0056]    Turning to  FIG. 10  is a profile view of an embodiment of the thermoplastic flexor  201  encased in the seatback  105  and base  109  and mounted to the anchor of the frame  107 . This embodiment depicts the seatback  105  when under horizontal force, causing horizontal deflection D 1  in the seatback and vertical deflection D 2  near the fulcrums at the base. This embodiment discloses how flexor  201  defines, resists, and determines deflection within throughout the seatback by simultaneously defining deflection in the base  109 . Here the base  109  has deflected relative to the anchor and the flexor  201  is imparting a resistance throughout the base  109 . The frame  107  is not in view. 
         [0057]    Turning to  FIG. 11  is a profile view of the seating structure  101  of the current disclosure. In this embodiment, the seat  103 , seatback  105  and base  109  comprise a unibody shell  104 . The seat  103 , seatback  105 , and base  109  further have a continuous semi-annular flange that extends to partially cover the thermoplastic flexor  201 . The unibody shell and flexor  201  are secured to the frame  107 , which in this case has four legs, through an anchor. 
         [0058]    Turning to  FIG. 12  is a magnified view of  FIG. 11 , focusing particularly on the bend in the base portion  109  connecting the seat  103  and seatback  105  portions of the seating structure  101  employing a unibody shell  102 . The continuous semi-annular flange partially covering the thermoplastic flexor  201  is more clearly visible. 
         [0059]    Turning to  FIG. 13 , is a section view of  FIG. 12 . Exposed is the thermoplastic flexor  201  nested and mechanically secured to the rear of the seat  103 , seatback  105 , and base portions  109  of a unibody chair shell  104 . The thermoplastic flexor  201  is further connected to the frame  107  through an anchor. 
         [0060]    Turning to  FIG. 14  is a front isometric view of an embodiment of the seating structure  101  disclosed herein. The unibody chair shell  104  is seen in ghost, and the chair frame  107 , which has four legs, is connected to the underside of the seat portion  103 . A thermoplastic flexor  201  is seen on each side of the chair, extending from the seatback portion  105  through the base portion  109  to the seat portion  103  and connected to the anchor at the frame  107 . In this embodiment, the flexor  201  is separately manufactured and affixed to the rear or the shell  104  through mechanical attachment means. 
         [0061]    Turning to  FIG. 15  is a rear isometric view of an embodiment of the seating structure  101  disclosed herein. The unibody chair shell  104  is seen in ghost, and the chair frame  107 , which has four legs, is connected to the underside of the seat portion  103 . A thermoplastic flexor  201  is seen on each side of the chair, extending from the seatback portion  105  through the base portion  109  to the seat portion  103  and connected to the anchor at the frame  107 . In this embodiment, the flexor  201  is separately manufactured and affixed to the rear or the shell  104  through mechanical attachment means. This configuration further illustrates how the flexors  201 , are only partially disposed within the base  109 . 
         [0062]    Turning to  FIG. 16  is a sectional profile view of an embodiment of the disclosed seating structure  101  employing a unibody shell  104 . The section has been cut through the base  109  and thermoplastic flexor  201  to expose its mechanical connection and nested relationship to the rear of the seatback portion  105  and the base portion  109 , extending to the underside of the seat portion  103  and connected to the frame  107  through an anchor. 
         [0063]    Turning to  FIG. 17  is a magnified view of  FIG. 16 , focusing particularly on the bend in the base portion  109 . The section has been cut through the thermoplastic flexor  201  to expose its mechanical connection and nested relationship to the rear of the seatback portion  105  and the base portion  109 , extending to the underside of the seat portion  103  of the unibody shell  104 . 
         [0064]    Turning to  FIG. 18  is an isometric view of an embodiment of the seating structure  101  disclosed, including armrests extending from the frame  107  for supporting a user&#39;s arms. The thermoplastic flexor  201  is not in view, as it is obscured by the two-piece chair shell  102 . 
         [0065]    Turning to  FIG. 19  is an isometric view of an embodiment of an alternative frame  107  assembly of the seating structure  101  disclosed, here including a lift comprising a pneumatic cylinder on wheels. The thermoplastic flexor  201  is not in view, as it is obscured by the two-piece chair shell  102 . 
         [0066]    Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the embodiments disclosed and described herein. Therefore, it is understood that the illustrated and described embodiments have been set forth only for the purposes of examples and that they are not to be taken as limiting the embodiments as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the embodiments include other combinations of fewer, more or different elements, which are disclosed above even when not initially claimed in such combinations. 
         [0067]    The definitions of the words or elements of the following claims are, therefore, defined in this specification to not only include the combination of elements which are literally set forth. It is also contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a subcombination(s). 
         [0068]    Furthermore, to the extent that the term “having,” “includes,” or “wherein” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.