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 INVENTION  
       [0001]     The present invention is directed to a viewport for use with a door or wall, and more particularly, is directed to a frameless viewport for a door of an air handling unit.  
       BACKGROUND OF THE INVENTION  
       [0002]     Viewports for doors are desirable as they provide a means to visually perceive what is otherwise hidden by the door without having to open the door. This capability is especially desirable for access doors for air handling units, wherein operation of a ventilation system must typically be interrupted to safely open the access door. Similarly, viewports can be installed in wall panels of an enclosure. Typically, the viewport includes a frame surrounding one more panes of a transparent material. The panes are typically environmentally sealed to prevent the formation of condensation between the panes, which obscures viewing through the panes. The frame typically is provided in two portions, each portion being assembled to openings formed in opposed door or wall panels, the two portions being drawn together by fasteners. Unfortunately, the frame adds significant expense to the viewport construction.  
         [0003]     What is needed is a frameless viewport that can be easily installed between opposed door or wall panels.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention relates to a viewport for a door or wall including substantially aligned openings disposed in inner and outer panels of a door or wall. A pane assembly is configured to permit viewing therethrough, the pane assembly being secured into position between the inner and outer panels in alignment with the openings. An injected insulating material is disposed between the inner and outer panels and around the pane assembly to substantially fill an open space between the inner and outer panels, the insulating material being configured and disposed to maintain the secured position of the pane assembly.  
         [0005]     The present invention further relates to a viewport for an air handling unit including substantially aligned openings disposed in inner and outer panels of a door or wall of an air handling unit. A pane assembly is configured to permit viewing therethrough, the pane assembly being secured into position between the inner and outer panels in alignment with the openings. An injected insulating material is disposed between the inner and outer panels and around the pane assembly to substantially fill an open space between the inner and outer panels, the insulating material being configured and disposed to maintain the secured position of the pane assembly.  
         [0006]     The present invention still further relates to a method for installing a viewport. The method includes providing inner and outer panels of a door or wall, and securing a pane assembly into position between the inner and outer panels in alignment with the openings, the pane assembly configured to permit viewing therethrough. The method also includes disposing injected insulating material between the inner and outer panels to substantially fill an open space between the inner and outer panels, the insulating material being configured and disposed to maintain the secured position of the pane assembly.  
         [0007]     An advantage of the present invention is that it is inexpensive to fabricate.  
         [0008]     A further advantage of the present invention is that it requires fewer parts.  
         [0009]     A still further advantage of the present invention is that it has a compact construction.  
         [0010]     Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an exploded perspective view of a frameless viewport of the present invention.  
         [0012]      FIG. 2  is a perspective view of an assembled viewport of  FIG. 1  of the present invention.  
         [0013]      FIG. 3  is an elevation view of an assembled viewport of  FIG. 1  of the present invention.  
         [0014]      FIG. 4  is an exploded perspective view of an alternate embodiment of a frameless viewport of the present invention.  
         [0015]      FIG. 5  is an exploded perspective view of a viewing pane subassembly of the present invention.  
         [0016]      FIG. 6  is a partial elevation view of a viewing pane subassembly of  FIG. 5  of the present invention.  
         [0017]      FIG. 7  is a partial elevation view of an alternate embodiment of a viewing pane subassembly of the present invention. 
     
    
       [0018]     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     One embodiment of a viewport  10  is shown in  FIGS. 1 and 2 . Preferably, viewport  10  is used with an air handling unit (not shown), the view port  10  being formed in a wall or an access door of the air handling unit. An opening  14  is formed in a panel  12  and an opening  18  is formed in a panel  16 , the openings  14 ,  18  being substantially aligned when the panels  12 ,  16  are brought together during assembly. A pane  22  of a substantially transparent material having suitable optical, strength and thermal insulative properties, sized slightly larger than the openings  14 ,  16 , is provided for insertion between the panels  12 ,  16  in substantial alignment with the openings  14 ,  16 . To permit pane  22  to span the distance between the panels  12 ,  16  as assembled, a spacer  24  is interposed between one side of pane  22  and panel  12 , as shown in  FIG. 1 . The combination of pane  22  and spacer  24  defines a pane subassembly  20 . Preferably, a tape  32  having opposed adhesive surfaces is applied along the periphery of opening  18  on an inner surface  30  of panel  16  to secure the pane  22  to the panel  16  and along the periphery of opening  14  on an inner surface  40  of panel  12  to secure the spacer  24  to the panel  12 . Alternately, tape  32  can be first applied to the pane  22  and to the spacer  24 , or portions of tape  32  can first be applied to panel  12 ,  16 . Stated another way, the order of surfaces to which tape  32  is applied is not important. Upon installation of the pane assembly  20  between panels  12 ,  16  as shown by  FIG. 2 , insulating material (not shown), such as a polyurethane foam, is injected between the panels  12 ,  16  to further secure the position of the pane subassembly  20  as originally installed.  
         [0020]     Referring to  FIGS. 1 and 3 , spacer  24  preferably includes a plurality of interconnected legs  25  substantially corresponding to the periphery of pane  22  along a surface  38 . Each leg  25  includes a web  26  that extends at opposite ends preferably transverse to the web  26  to form flanges  28 . The profile of the web  26  and flanges  28  of each leg  25  defines a C-section. Preferably, the flanges  28  of one side of the legs  25  abut surface  38  of the pane  22  and the flanges  28  of the other side of the leg  25  abut surface  40  of panel  12 . If required, as shown in  FIG. 3 , an application of tape  32  having opposed adhesive surfaces can be applied along the periphery of opening  14  along surface  40  of panel  12  to secure panel  12  to the flanges  28  of spacer  24 . Similarly, the surface of pane  22  opposite spacer  24  abuts surface  30  of panel  16 . If required, as shown in  FIG. 3 , an application of tape  32  having opposed adhesive surfaces can be applied along the periphery of opening  18  along surface  30  of panel  16  to secure panel  16  to pane  22 . Once the pane subassembly  20  has been installed, the junctures between the panels  12 ,  16 , pane  22  and the spacer  26 , which junctures are enhanced if required by adhesives, such as contained in tape  32 , are substantially fluid tight to prevent the flow of insulating material injected between the panels  12 ,  16 .  
         [0021]     Referring to  FIGS. 4-7 , an alternate embodiment of viewport  110  is provided which is substantially similar to viewport  10 , except pane subassembly  120  is substituted for pane subassembly  20 . Pane subassembly  120  preferably includes a plurality of panes  22 , each adjacent pane  22  being separated by a gasket  34 . Gasket  34  preferably defines a closed, contiguous geometric shape that abuts opposed surfaces of adjacent panes along their respective peripheries to provide a fluid tight seal therebetween without visually obscuring the view through the panes  22  once assembled. In a preferred embodiment, gaskets  34  will incorporate a desiccant to absorb moisture that could otherwise form on the inaccessible surfaces of adjacent panes  22 . In the embodiment shown in  FIG. 6 , which is a partial elevation view of the assembled pane subassembly  120 , the edges of the gaskets  34  and panes  22  are substantially aligned. However, in an alternate construction, such as shown in  FIG. 7 , a single gasket  134  can extend around the periphery of a panel  122  that is between outer panels  222 . Panel  122  is thus concealed when viewed from the side of the assembled panel subassembly  120 . Although panel  122  is shown as being smaller than panels  222 , it is to be understood that panels  122 ,  222  can have the same outside dimensions. It is also to be understood that a combination of gaskets  134 ,  34  can be used with a pane subassembly.  
         [0022]     Preferably, gasket  134  does not extend around the periphery of the outer panels  222 , as such a construction requires that the gasket  134  abuts surfaces  30  and  40  of respective panels  16 ,  12 . However, such a construction of gasket  134  is contemplated by the present invention, so long as there is substantially no flow of injected insulating material between gasket  134  and panels  12 ,  16 .  
         [0023]     One skilled in the art can appreciate that the number of panes can exceed three, and that one or more spacers  24  can be used with panel subassembly  20 ,  120 . Further, while tape  32  can be interposed between the junctures of any combination of panels, panes, gaskets and spacers, such tape may not be required if the junctures are sufficiently fluid tight to substantially prevent the flow of injected insulating material therebetween and the panel subassembly  20 ,  120  remains in the desired installed position. This combination is intended to include the application of tape on the panes or to a spacer or combination thereof. Any suitable treatment or process to achieve this, such as heat or pressure, can be used, if desired.  
         [0024]     It is to be understood that the panel openings and corresponding panes and gaskets can have any closed geometric shape.  
         [0025]     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Summary:
A viewport including substantially aligned openings disposed in inner and outer panels for a door or wall is provided. A pane assembly configured to permit viewing therethrough is provided, the pane assembly being secured into position between the inner and outer panels in alignment with the openings. An injected insulating material is disposed between the inner and outer panels and around the pane assembly to substantially fill an open space between the inner and outer panels, the insulating material being configured and disposed to maintain the secured position of the pane assembly.