You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE DISCLOSURE 
     This patent generally relates to insulated doors and, more specifically, to doors that include a flexible panel such as an insulated curtain. 
     BACKGROUND 
     Cold storage rooms are refrigerated areas in a building that are commonly used for storing perishable foods. Cold storage rooms are typically large enough for forklifts and other material handling equipment to enter. Access to the room is often through a power actuated insulated door that separates the room from the rest of the building. To minimize thermal losses when someone enters or leaves the room, the door preferably opens and closes as quickly as possible. 
     Vertically operating roll-up doors and similar doors with flexible curtains are perhaps some of the fastest operating doors available. When such a door opens, its curtain usually bends upon traveling from its closed position in front of the doorway to its open position on an overhead storage track or take-up roller. 
     Such bending is not a problem if the curtain is relatively thin. However, an insulated curtain may not bend as well due to the required thickness of the insulation. When a take-up roller or curved track bends a thick curtain, relative translation may occur between opposite faces of the curtain. Designing a thick, insulated curtain that can accommodate such translation can be challenging. 
     Moreover, if an insulated curtain becomes temporarily creased or locally compressed along the horizontal line where the curtain bends, such a crease or compression might trap a pocket of air inside the curtain, and that trapped air might cause the curtain to bulge and adversely affect the door&#39;s operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing an example door in a closed position. 
         FIG. 2  is a front view similar to  FIG. 1  but showing the example door partially open. 
         FIG. 3  is a front view similar to  FIGS. 1 and 2  but showing the example door in an open position. 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a front view of the example door panel of  FIGS. 1-3  with a lower-left section of the panel&#39;s outer sheet cutaway. 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 . 
         FIG. 7  is a cross-sectional view similar to  FIG. 6  but with the insulation omitted to more clearly show one of the example baffles. 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 5 . 
         FIG. 9  is a cross-sectional view similar to  FIG. 8  but showing the example door panel being assembled. 
     
    
    
     DETAILED DESCRIPTION 
     Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify the same or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any example may be included with, a replacement for, or otherwise combined with other features from other examples. 
       FIGS. 1-4  illustrate a vertically operating door  10  that includes a flexible, insulated door panel  12  with means for managing undesirable air pressure conditions inside the panel. Door  10  is shown closed in  FIG. 1 , partially open in  FIG. 2 , and fully open in  FIGS. 3 and 4 . As door  10  opens and closes relative to a doorway  14 , door panel  12  bends over a mandrel  16 , which contributes to the air pressure problem that is addressed by the example methods and apparatus described herein. Mandrel  16  can be a fixed bar or a roller that extends across the width of doorway  14 . Although door panel  12  is shown having a certain double-bend, stored configuration, other stored configurations, such as coiled, wound on a roll tube, single-bend horizontal, serpentine, vertically planar, etc., are all well within the scope of this disclosure. Door  10  is particularly suited for a cold storage room. However, door  10  could also be applied to any other desired application. 
     With the exception of door panel  12  itself, the structure, operation and other details of door  10  are described and illustrated in U.S. Patent Application Publication No. US 2008/0110580 A1, which is hereby incorporated herein by reference in its entirety. Generally, a powered drive sprocket  18  ( FIG. 4 ) engages a cogged strip  20  at each lateral edge of door panel  12  to move door panel  12  between a lower guide track  22 , where door panel  12  is blocking doorway  14 , and an upper track  24  where door panel  12  is clear of the doorway. It should be noted, however, that door panel  12  can be applied to various other types of doors that operate with different drive or storage configurations. In each case, the thickness of the door panel, combined with air trapped therein and a bending of the panel, can cause the trapped air to balloon the bottom of the curtain or panel as the door opens. 
     Publication No. US 2008/0110580 A1 also explains the benefit of equipping an insulated door panel with an evacuation blower. However, unlike that published application, the example apparatus described herein enables the door panel  12  to be advantageously utilized without such a blower and associated hardware. 
     Instead of using an evacuation blower, door panel  12  includes a plurality of pliable baffles  26  ( FIGS. 5-9 ) that restrict the redistribution of air contained between a first sheet  28  and a second sheet  30  of door panel  12 . Sheets  28  and  30  are joined and generally sealed along their outer perimeter to create one large overall air chamber  32  between sheets  28  and  30 . Baffles  26  divide chamber  32  into a plurality of more manageable smaller chambers  34 . For illustrative clarity, baffles  26  and chambers  32  and  34  are shown in  FIG. 5  to extend slightly less than a full width  40  of door panel  12 , however, baffles  26  and chambers  32  and  34  preferably extend the full width of door panel  12  as depicted in  FIG. 5 . As door  10  opens and creates a horizontal crease in sheets  28  and  30  (e.g., where door panel  12  bends over mandrel  16 ), baffles  26  help prevent air trapped within chamber  32  from over inflating the lower end of door panel  12 . Thus, baffles  26  prevent the area between mandrel  16  and a lower leading edge  36  of door panel  12  from bulging excessively as door  10  opens. 
     While the division of large chamber  32  into smaller, more manageable chambers  34  helps solve the problems caused by air trapped in door panel  12 , baffles  26  used for this purpose may have other desirable properties. For example, baffles  26  may be sufficiently flexible to accommodate some relative translation between sheets  28  and  30  as door panel  12  bends over mandrel  16 . The flexibility of baffles  26  may also enable door panel  12  to restorably break away if something were to accidentally collide with the door. Additionally or alternatively, baffles  26  may be sufficiently flexible to conformingly mate with the lateral edges or vertical seams  33  of sheets  28  and  30  so that there is minimal leakage or air exchange between chambers  34 . Further, in some examples, baffles  26  preferably are sufficiently stiff to maintain a desired spacing between sheets  28  and  30 , particularly in examples where insulation is not used for maintaining such spacing. Further yet, in some examples, baffles  26  preferably have a thermal conductivity that generally is less than or equal to that of sheets  28  and  30 . The R-value of air enhanced with insulation in chambers  34  may be sufficient for preventing frost from forming on door panel  12 . However, if baffles  26  have relatively high thermal conductivity, frost lines might form on sheet  28  or  30  where baffles  26  connect to those sheets. 
     Although the actual construction of door panel  12  may vary, the illustrated examples have sheets  28  and  30  being made of any suitable polymeric or natural fabric material that is preferably pliable and can be joined along their outer perimeter by adhesion, tape, melting/fusing/welding, sewing, hook-and-loop fastener, snaps, rivets, zipper, etc. Substantially the entire outer perimeter, including seams  33  and the upper and lower edges of door panel  12 , is preferably sealed to prevent appreciable amounts of air from flowing in and out of chamber  32 . Inhibiting moist air from repeatedly entering chamber  32  prevents mold-promoting moisture from condensing inside chamber  32  on a panel sheet that is facing, for example, a cold storage room. 
     Baffles  26  can be made of a material similar to or different than that of sheets  28  and  30 . The flexibility of sheets  28  and  30  enables door panel  12  to bend over mandrel  16 , while the flexibility of baffles  26  enables limited relative translation between sheets  28  and  30  as door  10  opens and closes. As door  10  opens or closes and door panel  12  travels and bends across mandrel  16 , this action urges relative vertical translation between sheets  28  and  30 . Thermal insulation  38 , such as porous foam pads or polyester mats, preferably is installed within chambers  34 . 
     For the illustrated examples, baffles  26  are horizontally elongate, which enable them to not only restrict vertical airflow within door panel  12  but also to accommodate relative vertical translation between sheets  28  and  30 . In other examples, door panel  12  is provided with vertically elongate baffles or a combination of vertical and horizontal baffles. 
     To effectively restrict airflow within door panel  12 , horizontally elongate baffles  26  preferably extend along at least most of the full width  40  of door panel  12 . To facilitate manufacturing, however, baffles  26  can be made slightly shorter than the panel&#39;s full width  40  to make it easier to join the lateral vertical edges of sheets  28  and  30  together. Baffles  26  being a little shorter than full width  40  of door panel  12  places the plurality of air chambers  34  in fluid communication with each other. Thus, as door  10  opens and door panel  12  travels across mandrel  16 , some air within door panel  12  will be temporarily redistributed to at least one of the lower chambers (e.g., air chamber  34 ′) of the plurality of chambers  34 , thereby slightly increasing the air pressure within chamber  34 ′ temporarily, but not really detrimentally. 
     Although door panel  12  could be manufactured by several different methods,  FIG. 9  illustrates one example manufacturing method. One horizontal edge of each baffle  26  is melted or ultrasonically welded to first sheet  28 , thereby creating a plurality of fused joints  42  between sheet  28  and each of baffles  26 . Fusing baffles  26  to at least one of sheets  28  and  30  is schematically depicted by the block at reference number  44  of  FIG. 9 . Alternate methods of attaching baffles  26  in place include, but are not limited to, bonding, taping, sewing, fastening via hook-and-loop fastener, riveting, etc. 
     An outer perimeter of sheet  28  is fused, sewn or otherwise connected to sheet  30  as schematically depicted by the block at reference number  46  of  FIG. 9 . The plurality of baffles  26  are installed between sheets  28  and  30 , as schematically depicted by arrow  48  and insulation  38  is installed within chambers  34 , as schematically depicted by arrows  50 . The example method represented by the block at reference number  44  and arrows  48  and  50  may be done generally together in a progressive sequence from one end of door panel  12  to another or in any other suitable order.  FIG. 9 , for example, shows door panel  12  being assembled progressively from the bottom up. 
     At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
     In some examples, a door panel is comprised of two pliable sheets with a plurality of pliable baffles therebetween, wherein the baffles are horizontally elongate to not only restrict airflow within the panel but also to accommodate relative vertical translation between the two sheets. 
     In some examples, the baffles are sufficiently flexible or pliable to enable the two sheets to pinch together as the panel bends over a mandrel. 
     In some examples, a door panel is comprised of two pliable, generally parallel sheets to create an overall air chamber. The panel also includes a plurality of baffles that divide the overall air chamber into a plurality of smaller, more manageable chambers. 
     In some examples, the smaller, more manageable chambers are in fluid communication with each other. 
     In some examples, the horizontal baffles do not extend the full width of the door panel so that the perimeter of the panel&#39;s outer sheets can be readily joined to each other. 
     In some examples, the horizontal baffles extend as wide as possible to minimize fluid communication between the smaller chambers. 
     In some examples, the air pressure within the lower chamber temporarily increases as the door opens. 
     In some examples, the internal baffles are fused rather than sewn to the outer sheets for ease of manufacturing and to minimize air leakage between the interior and exterior of the door panel. 
     Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of the coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.

Summary:
An example of a vertically operating door includes a flexible panel comprising two pliable sheets of material with a plurality of pads or mats of thermal insulation between the two sheets. In some examples, a plurality of horizontally elongate baffles made of pliable strips of material are installed between the two sheets. The baffles effectively divide one large interior volume between the sheets into more manageable smaller volumes or chambers. The baffles restrict the air between the sheets from being forced to the bottom of the panel as the panel ascends and bends across an overhead roller. Without the baffles and smaller chambers, the panel sheets in the area near the bottom of the panel would tend to bulge outward as the door opens.