Abstract:
A multi-layered support structure provides ergonomic, adaptable seating support. The multi-layered support structure includes multiple cooperative layers to maximize global comfort and support while enhancing adaptation to localized variations in a load, such as in the load applied when a person sits in a chair. The cooperative layers each include elements such as pixels, springs, support rails, and other elements to provide this adaptable comfort and support. The multi-layered support structure also uses aligned material to provide a flexible yet durable support structure. Accordingly, the multi-layered support structure provides maximum comfort for a wide range of body shapes and sizes.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority to both of U.S. Provisional Patent Application No. 61/135,997, filed Jul. 25, 2008, titled MULTI-LAYERED SUPPORT STRUCTURE, and U.S. Provisional Patent Application No. 61/175,670, filed May 5, 2009, titled MULTI-LAYERED SUPPORT STRUCTURE, which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The invention relates to load support structures. In particular, the invention relates to multi-layered seating structures. 
         [0004]    2. Related Art 
         [0005]    Most people spend a significant amount of time sitting each day. Inadequate support can result in reduced productivity, body fatigue, or even adverse health conditions such as chronic back pain. Extensive resources have been devoted to the research and development of chairs, benches, mattresses, sofas, and other load support structures. 
         [0006]    In the past, for example, chairs have encompassed designs ranging from cushions to more complex combinations of individual load bearing elements. These past designs have improved the general comfort level provided by seating structures, including providing form-fitting comfort for a user&#39;s general body shape. Some discomfort, however, may still arise even from the improved seating structures. For example, a seating structure, though tuned to conform to a wide variety of general body shapes, may resist conforming to a protruding wallet, butt bone, or other local irregularity in body shape. This may result in discomfort as the seating structure presses the wallet or other body shape irregularity up into the seated person&#39;s backside. 
         [0007]    Thus, while some progress has been made in providing comfortable seating structures, there remains a need for improved seating structures tuned to fit and conform to a wide range of body shapes and sizes. 
       SUMMARY 
       [0008]    A multi-layered support structure may include a global layer, a local layer, and a top mat layer. The global layer provides controlled deflection of the seating structure upon application of a load. The global layer includes multiple support rails which also support the local layer. The global layer may also include multiple aligned regions which may include an aligned material to facilitate deflection of the global layer when a load is imposed. 
         [0009]    The local layer facilitates added and independent deflection upon application of a load to the multi-layered support structure. The local layer includes multiple spring elements supported by the multiple support rails. The multiple spring elements each include a top and a deflection member. Each of the multiple spring elements may independently deflect under a load based upon a variety of factors, including the spring type, relative position of the spring element within the multi-layered support structure, spring material, spring dimensions, connection type to other elements of the multi-layered support structure, and other factors. 
         [0010]    The top mat layer may be the layer upon which a load is applied. The top mat layer includes multiple pixels and bull nose extension fingers positioned above the multiple spring elements. The multiple pixels and bull nose extension fingers contact with the tops of the multiple spring elements. Like the multiple spring elements, the multiple pixels and multiple bull nose extension fingers may also provide a response to an applied load substantially independent of the responses of an adjacent pixel. 
         [0011]    Accordingly, the multi-layered support structure includes cooperative yet independent layers, with each layer including cooperative yet independent elements, to provide maximized global support and comfort to an applied load while also adapting to and supporting localized load irregularities. Further, the load support independence provided by the multi-layered support structure allows specific regions to adapt to any load irregularity without substantially affecting the load support provided by adjacent regions. 
         [0012]    Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    The system may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
           [0014]      FIG. 1  shows a portion of a layered support structure. 
           [0015]      FIG. 2  shows a broader view of the support structure shown in  FIG. 1 . 
           [0016]      FIG. 3  shows a top view of a global layer. 
           [0017]      FIG. 4  shows a portion of the support rail including the node connected between two straps. 
           [0018]      FIG. 5  shows a top view of a local layer. 
           [0019]      FIG. 6  shows a portion of the spring attachment member. 
           [0020]      FIG. 7  shows a top view of an exemplary local layer. 
           [0021]      FIG. 8  shows a top view of a top mat layer. 
           [0022]      FIG. 9  shows the underside of a pixel within the top mat layer. 
           [0023]      FIG. 10  is a process for manufacturing a layered support structure. 
           [0024]      FIG. 11  shows a global layer stretched by an assembly apparatus. 
           [0025]      FIG. 12  shows a pre-aligned global layer. 
           [0026]      FIG. 13  shows a close-up view of a portion of a pre-aligned global layer. 
           [0027]      FIG. 14  shows a top view of a global layer cavity mold and hot drop channel for forming a pre-aligned global layer. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    The layered support structure generally refers to an assembly of multiple cooperative layers for implementation in or as a load bearing structure, such as a chair, bed, bench, or other load bearing structures. The cooperative layers include multiple elements, including multiple independent elements, to maximize the support and comfort provided. The extent of the independence exhibited by the multiple elements may depend on, or be tuned to, individual characteristics of each element, the connection type used to interconnect the multiple elements, or other structural or design characteristics of the layered support structure. The multiple elements described below may be individually designed, positioned, or otherwise configured to suit the load support needs for a particular individual or application. The dimensions discussed below with reference to the various multiple elements are examples only and may vary widely depending on the particular desired implementation and on the factors noted below. 
         [0029]      FIG. 1  shows a portion of a layered support structure  100 . The layered support structure  100  includes a global layer  102 , a local layer  104 , and a top mat layer  106 . 
         [0030]    The global layer  102  includes multiple support rails  108  and a frame attachment  110 . Each support rail  108  may include one or more straps  112  and multiple nodes  114  connected between the straps  112 . Each strap may include aligned regions  116  and unaligned regions  118  defined along the length of the strap  112 . The nodes  114  may connect to adjacent straps between the unaligned regions  118  of the adjacent straps  112 . 
         [0031]    The local layer  104  includes multiple spring elements  120  above (e.g., supported by or resting on) the multiple support rails  108 . Each of the multiple spring elements  120  includes a top, a deflectable member  122 , and one or more node attachment members  124 . In  FIG. 1 , the deflectable member  122  includes two spiral arms  126 . The spring elements  120  may alternatively include a variety of spring types, such as those disclosed in U.S. application Ser. No. 11/433,891, filed May 12, 2006, which is incorporated herein by reference. 
         [0032]    The top mat layer  106  includes multiple pixels and bull nose extension fingers  128 . Each of the multiple pixels includes an upper surface and a lower surface. The lower surface of each pixel may include a stem which contacts the top of at least one of the spring elements  120 . Each of the bull nose extension fingers  128  may also include an upper surface  130  and a lower surface. The lower surface of each bull nose extension finger  128  may include one or more stems that each contact with the top of at least one of the spring elements  120 . 
         [0033]    The global layer  102  may be injection molded from a flexible material such as a thermal plastic elastomer (TPE), including Arnitel EM400 or 460, a polypropylene (PP), a thermoplastic polyurethane (TPU), or other soft, flexible materials. 
         [0034]    The global layer  102  connects to a frame  132  via the frame attachment  110 . The frame attachment  110  may be connected to the end of the straps  112  of the support rails  108  and oriented substantially perpendicular to the straps  112 .  FIG. 1  shows a frame attachment  110  that includes discrete segments  134 . The frame attachment  110  may define by a gap  136  between each segment  134 . Each of the discrete segments  134  may connect to the ends of two or more adjacent straps  112 . The frame attachment  110  may include a single segment extending along an entire side of the global layer  102 , such as the frame attachment shown in  FIG. 3 . 
         [0035]    In  FIG. 1 , each support rail  108  includes two cylindrical straps  112  extending substantially in parallel. The support rails  108 , however, may include alternative configurations. For example, the support rails  108  may include a single strap, or multiple straps. The support rails  108  of the global layer  102  may include a varying number of straps  112  tailored to various factors, such as the location of the support rail  108  within the global layer  102 . The support rails  108  may include alternative geometries. For example, the straps  112  of the support rails  108  may include four sides with multiple ends. An example of such straps is disclosed in U.S. application Ser. No. 11/433,891. 
         [0036]    A strap  112  may include multiple aligned regions  116  and multiple unaligned regions  118  defined along the strap  112 . The strap  112  may include alternating aligned and unaligned regions  116  and  118 . Each of the aligned and unaligned regions may be defined by a cross-sectional area. The cross-sectional area of each aligned region defined along a strap may vary and be tailored to the position of the aligned region along the strap. The cross-sectional area may be proportional to the position of the aligned region relative to a gate location of the mold. For example, the gate location corresponds to the middle of the strap, where the aligned regions have a greater cross-sectional area the more distant they are from the middle. As shown in  FIG. 1 , the cross-sectional area of the unaligned regions may be greater than that of the adjacent aligned regions. The aligned regions defined along the straps of the support rails may be aligned using a variety of methods including compression and/or tension aligning methods. 
         [0037]    The unaligned region  118  and aligned region  116  of the adjacent straps  112  may substantially line up with each other. As shown in  FIG. 1 , the nodes  114  may connect between adjacent unaligned regions  118  of adjacent straps  112 . Each node  114  may include a spring connection for connecting to a spring element  120  of the local layer. The spring connection may be an opening defined in the node  114  for receiving a corresponding spring element  120 , such as shown in  FIG. 4 . 
         [0038]    The global layer  102  may or may not be pre-loaded. For example, prior to securing the global layer  102  to the frame, the global layer  102  may be formed, such as through the injection molding process, with a shorter length than is needed to secure the global layer  102  to the frame. Before securing the global layer  102  to the frame, the global layer  102  may be stretched or compressed to a length greater than its original length. As the global layer  102  recovers down after being stretched, the global layer  102  may be secured to the support structure frame when the global layer  102  settles to a length that matches the width of the frame. 
         [0039]    As another alternative, the global layer  102  may recover down and then be repeatedly re-stretched until the settled down length of the global layer  102  matches the width of the frame. The global layer  102  may be pre-loaded in multiple directions, such as along its length or its width. In addition, different pre-loads may be applied to different regions of the global layer  102 . Applying different pre-loads according to region may be done in a variety of ways, such as by varying the amount of stretching or compression at different regions and/or varying the cross-sectional area of different regions. 
         [0040]    The multiple spring elements  120  of the local layer  104  may include a variety of dimensions according to a variety of factors, including the spring element&#39;s relative location in the support structure  100 , the needs of a specific application, or according to a number of other considerations. For example, the heights of the spring elements  120  may be varied to provide a three-dimensional counter to the support structure  100 , such as by providing a dish-like appearance to the support structure  100 . In this example, the height of the spring elements  120  positioned at a center portion of the local layer  104  may be less than the height of spring elements  120  positioned at outer portions of the local layer  104 , with a gradual or other type of increase in height between the center and outer portions of the local layer  104 . 
         [0041]    The local layer  104  may include a variety of other spring types. Examples of other spring types, as well as how they may be implemented in a support structure, are described in U.S. application Ser. No 11/433,891, filed May 12, 2006, which is incorporated herein by reference. The spring types used in the local layer  104  may include alternative orientations. For example, the spring types may be oriented upside-down, relative to their orientation described in this application. In this example, the portion of the spring described in this application as the top would be oriented towards and connect to the global layer  102 . Further, in this example the deflectable members  122  may connect to the top mat layer  106 . The deflectable members  122  may connect to the top mat layer  106  via multiple spring attachment members  124 . However, the examples discussed in this application do not constitute an exhaustive list of the spring types, or possible orientations of spring types, that may be used to form the local layer  104 . The spring elements  120  may exhibit a range of spring rates, including linear, non-linear decreasing, non-linear increasing, or constant rate spring rates. 
         [0042]    The local layer  104  connects to the global layer  102 . In particular, the spring attachment members  124  connect on the nodes  114  positioned between the unaligned regions  118  of adjacent straps  112 . This connection may be an integral molding, a snap fit connection, or other connection method. The multiple spring elements  120  may be injection molded from a POM, such as Ultraform N 2640 Z6 UNC Acetal or Uniform N 2640 Z4 UNC Acetal, from a TPE, such as Arnitel EM 460, EM550, or EL630, a TPU, a PP, or from other flexible materials. The multiple spring elements  120  may be injection molded individually or as a sheet of multiple spring elements. 
         [0043]    As the local layer  104  includes multiple substantially independent deflectable elements, i.e., the multiple spring elements, adjacent portions of the local layer  104  may exhibit substantially independent responses to a load. In this manner, the support structure  100  not only deflects and conforms under the “macro” characteristics of the applied load, but also provides individual, adaptable deflection to “micro” characteristics of the applied load. 
         [0044]    The local layer  104  may also be tuned to exhibit varying regional responses in any particular zone, area, or portion of the support structure to provide specific support for specific parts of an applied load. The regional response zones may differ in stiffness or any other load support characteristic, for example. Certain portions of the support structure may be tuned with different deflection characteristics. One or more individual pixels which form a regional response zone, for example, may be specifically designed to a selected stiffness for any particular portion of the body. These different regions of the support structure may be tuned in a variety of ways. Variation in the spacing between the lower surface of each pixel and the local layer  104  (referring to the spacing measured when no load is present) may vary the amount of deflection exhibited under a load. The regional deflection characteristics of the support structure  100  may be tuned using other methods as well, including using different materials, spring types, thicknesses, cross-sectional areas, geometries, or other spring characteristics for the multiple spring elements  120  depending on their relative locations in the support structure. 
         [0045]    The top mat layer  106  connects to the local layer  104 . The lower surface of each pixel is secured to the top of a corresponding spring element  120 . The lower surface of each bull nose extension finger  128  may also be secured to the top of one or more corresponding spring elements  120 . These connections may be an integral molding, a snap fit connection, or other connection method. The lower surface of the pixel and/or bull nose extension finger  128  may connect to the top of the spring element  120 , or may include one or more stems or other extensions for resting upon or connecting to the spring element  120 . The top of each spring element  120  may define an opening for receiving the stem of the corresponding pixel or bull nose extension finger  128 . Alternatively, the top of each spring element  120  may include a stem or post for connecting to an opening defined in the corresponding pixel or bull nose extension finger  128 . 
         [0046]    When a load presses down on the top mat layer  106 , the multiple pixels press down on the tops of the multiple spring elements  120 . In response, the multiple spring elements  120  deflect downward to accommodate the load. The amount of deflection exhibited by an individual spring element  120  under a load may be affected by a spring deflection level associated with that spring element  120 . As the multiple spring elements  120  deflect downward, the lower surfaces of the multiple pixels and/or multiple bull nose extension fingers  128  move toward the global layer  104 . Relative to the ground, however, the spring elements  120  may deflect further in that the local layer  104  may deflect downward under a load as the global layer  102  deflects under the load. As such, the spring elements  120  may individually deflect under a load according to the spring deflection level, and may also, as part of the local layer  104  as a whole, deflect further as the global layer  102  bends downward under the load. 
         [0047]    The spring deflection level may be determined before manufacture and designed into the support structure  100 . For example, the support structure  100  may be tuned to exhibit an approximately 25 mm of spring deflection level. In other words, the support structure  100  may be designed to allow the multiple spring elements  120  to deflect up to approximately 25 mm. Thus, where the local layer  104  includes spring elements of 16 mm height (i.e., the distance between the top of the global layer  102  and the top of the spring element), the lower surfaces of the multiple pixels may include a 9 mm stem. As another example, where the local layer  104  includes spring elements of 25 mm height, the lower surfaces of the multiple pixels may omit stems, but may connect to the tops of the multiple spring elements. As explained above, the height of each spring element  120  may vary according to a number of factors, including its relative position within the support structure  100 . 
         [0048]    The multiple pixels of the top mat layer  106  may be interconnected with multiple pixel connectors, as shown in  FIG. 8  and described below. The top mat layer  106  may include a variety of pixel connectors, such as planar or non-planar connectors, recessed connectors, bridged connectors, or other elements for interconnecting the multiple pixels, as described below. The multiple pixel connectors may be positioned at a variety of locations with reference to the multiple pixels. For example, the multiple pixel connectors may be positioned at the corners, sides, or other positions in relation to the multiple pixels. The multiple pixel connectors provide an increased degree of independence as between adjacent pixels, as well as enhanced flexibility to the top mat layer  106 . For example, the multiple pixel connectors may allow for flexible downward deflection, as well as for individual pixels to move or rotate laterally with a significant amount of independence. 
         [0049]    The top mat layer  106  may be injection molded from a flexible material such as a TPE, PP, TPU, or other flexible material. In particular, the top mat layer  106  may be formed from independently manufactured pixels and bull nose extension fingers  128 , or may be injection molded as a sheet of multiple pixels. 
         [0050]    When under a load, the load may contact with and press down on the top mat layer  106 . Alternatively, the support structure  100  may also include a covering layer secured above the top mat layer  106 . The covering layer may include a cushion, fabric, leather, or other covering materials. The covering layer may provide enhanced comfort and/or aesthetics to the support structure  100 . 
         [0051]      FIG. 2  shows a broader view of the support structure  100  shown in  FIG. 1 . The top mat layer  106  is supported on the local layer  104 , which is supported on the global layer  102 . The global layer  102  is secured to the frame  132 . While  FIG. 2  shows a rectangular multi-layered support structure  100 , the support structure  100  may include alternative shapes, including a circular shape. 
         [0052]    The top mat layer  106  includes a pixel region  200  connected to a bull nose extension finger region  202 . The pixel region  200  includes multiple interconnected pixels  204 . The bull nose extension finger region  202  includes multiple interconnected bull nose extension fingers  128 . 
         [0053]    The top mat layer  106  also includes multiple pixel connectors to facilitate the connections between adjacent pixels  204  and bull nose extension fingers  128 . The pixel connectors are described in more detail below and a close-up of one pixel connector is shown in  FIG. 8 . 
         [0054]    The pixels  204  provide enhanced flexibility to the top mat layer  106 . The pixels  204  may include stems for connecting to a local layer  104 . The bull nose extension fingers  128  may facilitate connection of the top mat layer  106  to a seating structure. For example, the bull nose extension fingers  128  may be glidably inserted into a seating structure. For example, the seating structure may include tracks into which each bull nose extension finger glides. 
         [0055]      FIG. 2  shows the spring attachment members  124  of the multiple spring elements  120 . The spring attachment members  124  include a stem  206  extending downward towards the global layer  102 . Each stem  206  may be inserted into and secured within an opening defined in a corresponding node  114  of the global layer  102 . The stems  206  of the spring elements  120  are discussed in more detail below and are shown close-up in  FIG. 6 . The respective heights of the stems  206  may vary within the local layer  104  to provide counter to the support structure  100 . 
         [0056]      FIG. 3  shows a top view of a global layer  300 . As noted above in connection with  FIG. 1 , the global layer  300  includes multiple support rails  302  and one or more frame attachments  304 . The ends of the support rails  302  connect between two substantially parallel frame attachments  304 . In  FIG. 3 , the frame attachments  304  each comprise a unitary segment extending along the length of the frame attachment  304 . As shown in  FIG. 1 , the frame attachments may include discrete segments. 
         [0057]    The global layer  300  may be formed using an injection molding technique. In particular, the global layer  300  may be formed using a center gating injection molding technique in which the cavity mold is gated at or near positions of the cavity mold that correspond to the center of the support rails. An injection molding process may result in molding pressure loss within the molded apparatus, where the pressure loss may be greater in regions farther from the gate than regions closer to the gate. The center gating technique may facilitate symmetrical pressure loss along the support rails  302 . As pressure loss can affect alignment, a symmetrical pressure loss within the support rails may facilitate symmetrical alignment within the support rails  302 . 
         [0058]    Each support rail  302  comprises two straps  306  and multiple nodes  308  connected between adjacent straps. Each strap  306  includes aligned regions  310  and unaligned regions  312  defined along the length of the strap  306 . The aligned regions  310  may be defined by a cross-sectional area that is less than the cross-sectional area of the unaligned regions  312 . The cross-sectional area of each aligned region  310  defined along a strap  306  may be tuned to the relative location of the aligned region  310  on the strap  306 . The cross-sectional area of aligned regions  310  along a strap  306  may gradually increase the farther the aligned region  310  is from the center of the strap  306 . The cross-sectional area of the aligned regions  310  may also be tuned to the relative position of each aligned region  310  from the position of the gate. The cross-sectional area of each aligned region  310  may increase by between about 0.1% to about 1%, such as by about 0.5%, the more distant the aligned region is from the position of the gate. For example, the cross-sectional area of an aligned region may be between about 0.1% and about 1% greater than the cross-sectional area of an aligned region on the strap that is immediately closer to the position of the gate. 
         [0059]    The nodes  308  are connected between adjacent unaligned regions  312 . The nodes  308  may comprise a spring connection for connecting the global layer  300  to the local layer. The spring connection may be an opening defined in the node  308  for receiving a stem or other protrusion from a spring element. The nodes  308  may connect to the spring elements with a snap-fit connection, a press fit, or be integrally molded together. 
         [0060]    The frame attachments  304  facilitate connection of the global layer  300  to a frame. The frame attachments  304  may comprise an inside edge  314  and an outside edge  316 . Each strap  306  that is part of a support rail  302  may include two ends that connect to the inside edges  314  of the frame attachments  304 . The connection between the ends of adjacent straps  306  and the inside edge  314  of a frame attachment  304  may define an opening  318  between adjacent straps  306  along the inside edge  314  of the frame attachment  304 . 
         [0061]      FIG. 4  shows a portion of the support rail  302  including the node  308  connected between two straps  306 . In particular, the node  308  is connected between the adjacent unaligned regions  312  of the two straps  306 . Each strap  306  includes aligned regions  310  connected on either side of the corresponding unaligned region  312 . The cross-sectional area of the unaligned region  312  may be greater than the cross-sectional area of the aligned regions  310 . 
         [0062]    The node  308  may include a spring connection  400  for connecting the global layer  300  to a local layer. In  FIG. 4 , the spring connection  400  is an opening defined in the node  308  for receiving a stem or other protrusion of the local layer. The spring connection may alternatively be a stem or protrusion extending vertically above the node  308  for mating with an opening defined in the local layer. 
         [0063]      FIG. 5  shows a top view of a local layer  500 . The local layer  500  includes multiple interconnected spring elements  502 . The local layer  500  may be formed from a unitary piece of material. Each of the spring elements  502  includes a top  504 , at least one deflectable member  506 , and a spring attachment member  508 . The top  504  may define an opening for receiving a stem or other protrusion extending from the lower surface of a corresponding pixel of a top mat layer. 
         [0064]    The deflectable member  506  includes two spiral arms connected to and spiraling away from the top  504 . The cross-sectional area of the spiraled arms may be tapered or otherwise vary along the length of each arm. For example, the cross-sectional area of a spiral arm may gradually increase or decrease, beginning where the arm connects to the top  504 , along the length of the spiral arm and be smallest where the spiral arm connects to the spring attachment member  508 . The cross-sectional area of each spiral arm may be tailored to the relative location of the spring element  502  within the local layer  500 , a desired spring rate of the spring element  500 , or other factors. 
         [0065]    The spiral arms may include or be connected to the spring attachment member  508 . In  FIG. 5 , a spiral arm of two adjacent spring elements  502  connects the same spring attachment member  508 . 
         [0066]    The spring elements  502  are arranged in diagonal rows extending from one side of the local layer  500  to the other. The spring elements  502  may be interconnected with adjacent spring elements in the same diagonal row, but may not directly connect to spring elements in adjacent diagonal rows. In this configuration, spring elements  502  within a diagonal row may deflect or respond to a load substantially independently to the response of spring elements  502  in an adjacent diagonal row. 
         [0067]      FIG. 6  shows a portion of the spring attachment member  508 . In particular,  FIG. 6  shows a portion of the stem that may fit into an opening defined in the global layer. The stem includes a first cylindrical portion  600  that tapers down into a second cylindrical portion  602 , where the first cylindrical portion  600  has a greater cross-sectional area than does the second cylindrical portion  602 . The second cylindrical portion  602  may include a tapered end  604 . A portion of the second cylindrical portion  602  may be recessed to define a ridge  606  in the face of the second cylindrical portion  602 . The ridge  606  may facilitate a snap-fit connection between the stem and an opening defined in the global layer. 
         [0068]      FIG. 7  shows a top view of an exemplary local layer  700 . The local layer  700  includes multiple spring elements  702  that each includes a top  704 , a deflectable member  706 , and a spring attachment member  708 . The deflectable member  706  may include at least one spiraled arm  710 . For example,  FIG. 7  shows that some of the spring elements  712  near the edges of the local layer  700  include deflectable members having a single spiraled arm  710 . 
         [0069]      FIG. 8  shows a top view of a top mat layer  800  including a pixel region  802  and a bull nose region  804 . The pixel region  802  includes multiple hexagonal pixels  806  interconnected at their corners with pixel connectors  808 . Each of the multiple pixels includes an upper surface and a lower surface. The multiple pixels  806  are shown as hexagonal, but may take other shapes, such as rectangles, octagons, triangles, or other shapes. The lower surface includes a stem extending from the lower surface for connecting to the local layer. 
         [0070]    Each of the multiple pixel connectors  808  interconnects three adjacent pixels  806 . The multiple pixel connectors  808  may alternatively interconnect the multiple pixels  806  at their respective sides. The multiple pixels  806  may be planar, non-linear, and/or contoured. 
         [0071]    The multiple pixels  806  may define openings within each pixel. The openings may add flexibility to the top mat layer  800  in adapting to a load. The top mat layer  800  may define any number of openings within each pixel  806 , including zero or more openings. Additionally, each pixel  806  within the top mat layer  800  may define a different number of openings or different sized openings, depending, for example, on the pixel&#39;s respective position within the pixel region  802 . 
         [0072]      FIG. 9  shows the underside of a pixel  900  within the top mat layer  800  in which the lower surface  902  of the pixel  900  is shown facing upwards. In particular,  FIG. 9  shows the lower surface  902  of the pixel and a stem  904  extending from the lower surface  902 . The stem  904  may connect the pixel  900  to a spring element of a local layer. The connection between the stem  904  and a spring element may be an integral molding, a snap-fit connection, or another connection technique. 
         [0073]    The stem may include two ends  906  and  908 , a first end  906  connected to the lower surface of the pixel  902 , and a second end  908  for connecting to the spring element. The stem  904  may include one or more shoulders  910  extending laterally from the stem  904 , where the shoulder  910  has a height that is less than the height of the stem  904 . The second end  908  of the stem  904  may be tapered. The second or tapered end  908  may include a lip  912  extending beyond the stem  904 . To facilitate connection between the top mat layer and a local layer, the stem may be inserted into an opening defined in a top of the spring element. After the stem  904  passes a certain distance into the opening of the top of the spring element, the lip  912  may provide a catch to hold the stem  904  within the opening and resist removal of the stem  904 . The lip  912  may catch on the lower surface of the top, on a ridge defined in an inside edge of the top opening, or on another surface. 
         [0074]    The shoulders  910  may mate or otherwise be in contact with the upper surface of the top when the stem  904  passes through the top opening sufficiently for the lip to catch on the top and secure the pixel  900  to the top of the corresponding spring element. As an alternative, the stem  904  may omit the shoulders  910  and the lower surface  902  may contact with the upper surface of the top when the stem  904  mates with the top opening. 
         [0075]      FIG. 9  shows a pixel connector  914  connecting adjacent pixels. In  FIGS. 8 and 9 , the pixel connectors  914  connect between the corners of three adjacent hexagonal pixels. The pixel connector  914  includes arched arms  916  connected to a corner of one of the pixels to provide slack for each pixel&#39;s independent movement when a load is applied. The arched arms  916  may extend from the corner and meet at a junction  918  between the pixels. The junction  918  may be below the plane defined by the interconnected pixels. Other shapes, such as an S-shape, or other undulating shape may be implemented as part of the pixel connector  914 . The pixel connectors  914  may help reduce or prevent contact between adjacent pixels under deflection. The top mat layer  600  may alternatively omit the pixel connectors to increase the independence of the multiple pixels. While  FIGS. 8 and 9  show pixel connectors  914  connected at the corners of the multiple pixels, the multiple pixels may alternatively be connected at their respective sides. The pixel connectors  914  may, for example, include a U-shaped bend connected between the sides of adjacent pixels. 
         [0076]      FIG. 10  is a process  1000  for manufacturing a layered support structure. The process  1000  may be may automated or executed manually. An assembly apparatus may be utilized to carry out the process  1000 . The process  1000  obtains the global layer, local layer, and the top matt layer ( 1002 ). Each of the obtained global, local, and top mat layers may correspond to the layers described above, respectively. 
         [0077]    One or more of the global layer, local layer, and top mat layer may be formed using an injection molding technique. The global layer may be formed using a center gated injection molding technique. The gates used in the cavity mold for the injection molding process may be located on the portion of the cavity mold corresponding to approximately the middle of each support rail. The cavity mold may include a gate corresponding to each support rail, or each strap of the support rails, or according to other configurations. 
         [0078]    As discussed above, the global layer within a layered support structure includes straps with aligned and unaligned regions defined along the straps. Before alignment, the global layer may include pre-alignment regions defined along the straps. The pre-alignment regions may become the aligned regions after alignment or orientation of those regions. The global layer obtained for the process may have been previously aligned. 
         [0079]    As an alternative, the process  1000  may align or orient the global layer ( 1004 ). The process  1000  may stretch the global layer to orient the pre-alignment regions. Other alignment techniques may also be used, including compression. The assembly apparatus may grip or otherwise hold opposite sides of the global layer and stretch the global layer along the direction of the support rails. The global layer may be stretched between approximately 10-12 inches. The stretching may also cause each pre-alignment region to stretch between approximately four to approximately eight times its original length. 
         [0080]      FIG. 11  shows a global layer  1100  stretched by an assembly apparatus  1102 . The aligned regions  1104  of the stretched global layer  1100  correspond to the thinner portions of each strap  1106 . The unstretched or unaligned regions  1108  of the global layer correspond to the positions at which a node  1110  is connected between adjacent straps  1106 . The global layer  1100  includes openings  1112  defined between adjacent nodes and adjacent straps of the global layer  1100 . The cross-sectional area of each opening  1112  increases as the global layer  1100  is stretched. 
         [0081]    While the global layer is stretched according to block  1004  of the process  1000 , node locators may be inserted into the openings  1112  ( 1006 ). The node locators may be part of or separate from the assembly apparatus. The node locators may be blocks that fit in the openings  1112 . 
         [0082]    The process  1000  may connect the local layer to the global layer ( 1008 ). As discussed above, the local layer may include spring elements having spring attachment members that facilitate connection of the local layer to the global layer, such as the spring attachment member  508  shown in  FIGS. 5 and 6 . The process  1000  may guide the spring attachment members into corresponding openings defined in the nodes of the global layer until a snap-fit or other connection type is achieved. 
         [0083]    The process  1000  connects the top mat layer to the local layer ( 1010 ). As discussed above, the top mat layer may include pixels having one or more stems extending downward from the pixels. The stems may facilitate connection of the top mat layer to the local layer. The process  1000  may guide the stems into corresponding openings at the top of each spring element until a snap-fit or other connection type is achieved. 
         [0084]    The process  1000  may assemble the layered support structure in an upside-down orientation relative to the assembly apparatus, or relative to the orientation of the layered support structure&#39;s intended use (e.g., in a chair). For example,  FIG. 10  shows the assembly apparatus from a top view perspective holding the global layer with its underside facing up, i.e., the side of the global layer viewable in  FIG. 10  is the side that would typically face down in a chair application. 
         [0085]    In this example, the node locators (according to  1006 ) may be inserted from above the upside-down oriented global layer down into the openings  1112 . According further to this example, the process  1000  may connect the local layer to the global layer (according to  1008 ) by bringing the local layer, oriented upside-down relative to the assembly apparatus, and guiding the spring attachment members up into the corresponding openings defined by the nodes of the global layer until snap-fit or other connection type is achieved, such that the top of each spring element is oriented downward relative to the assembly apparatus. Likewise, the process  1000  may connect the top mat layer to the local layer (according to  1010 ) be bring the top mat layer, oriented upside-down relative to the assembly apparatus, and guiding the stems of the pixels up into corresponding openings at the top of each spring element until a snap-fit or other connection type is achieved, such that the top of the top mat layer is oriented downward relative to the assembly apparatus. 
         [0086]    The process  1000  retracts the node locators ( 1012 ) from the assembled layered support structure. The process  1000  may secure the assembled layered support structure to a frame, such as the frame of a chair, or may provide the assembled layered support structure to another process for frame attachment. 
         [0087]      FIG. 12  shows a pre-aligned global layer  1200 . The pre-aligned global layer  1200  may be provided using an injection molding process. The gate locations  1202  for the molding process may be located at the center, or near the center of each pre-aligned support rail  1204 . The gate locations  1202  may be located at a node  1206  or other portion of each pre-aligned support rail  1204 . In  FIG. 12 , the gate location is at a node  1206  located near the center of each pre-aligned support rail  1204 . 
         [0088]      FIG. 13  shows a close-up view of a portion of the pre-aligned global layer  1200  shows in  FIG. 12 . In particular,  FIG. 13  shows the gate location  1202  on the node  1206 . The hot drop depression  1300  in the unaligned region  1302  connected to the node  1206  may be product of the molding process. For example, the hot drop depression  1300  may correspond to a depression in the cavity mold for providing clearance to a hot drop tip. 
         [0089]      FIG. 14  shows a top view of a global layer cavity mold  1400  and hot drop channels  1402  for forming a pre-aligned global layer, such as the pre-aligned global layer  1200  shows in  FIG. 12 , though an injection molding process. The positions of the hot drops  1402  relative to the cavity mold correspond approximately to the gate locations of the mold. 
         [0090]    While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.