Abstract:
An air conditioning unit and method of mounting the same in a hole in a wall, particularly a hole housing a window. The unit includes a front section disposed inside the building on a first side of the hole; and a rear section disposed outside the building on a second side of the hole. A duct extends between the front and rear sections and is clampingly engaged between the sill and a bottom end of the window. The duct includes a first duct member which moves cooled air in a first direction towards the inside of the building; and a second duct member which moves return air in a second direction away from the inside of the building. The duct is changeable in length to alter the distance between the front and rear sections so as to accommodate the air conditioning unit&#39;s installation in windows in different thickness walls.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/672,438 filed Jul. 17, 2012, the entire specification of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    This invention relates generally to air conditioners. More particularly, this invention relates to a window-mounted air conditioning unit. Specifically, this invention is directed to an air conditioning unit which includes an expandable duct that enables the unit to be installed in holes or windows defined in different thickness walls, and to a method of installing the unit therein. 
         [0004]    2. Background Information 
         [0005]    Window-mounted air conditioning units are known in the art. Typically, these devices are generally rectangular in overall shape and are installed in the lower part of a double hung window. When installed, a bottom wall of the unit sits on part of the sill and the bottom of the lower window engages the top wall of the unit. The unit is thus sandwiched between the sill and the lower window and is thereby held in place. 
         [0006]    There are a number of problems with these units. Firstly, they are difficult and potentially dangerous to install, especially in instances where they are installed in windows that are on a second or higher story of a building. Even small air conditioning units weigh quite a lot and that weight is unevenly distributed within the device. Consequently, the installer may accidentally lose control of the unit during installation and it may drop some distance to the ground below, leading to damage to the unit and potential injury to passersby. 
         [0007]    Secondly, the units take up a substantial part of the space defined by the window. This reduces the amount of light coming into a room through that window. Still further, the units do not occupy the entire width of the window and because of the overall height of the unit; fairly substantially gaps are created on either side thereof. Even though baffles or some other type of obstruction are placed on either side of the unit, there may be fairly substantial exchange of air between the interior of the room and the air outside the building. This reduces the overall efficiency and effectiveness of the air conditioning unit. Additionally, the baffles block a lot of the light that could otherwise illuminate the interior of the room. 
         [0008]    Additionally, previously known window air-conditioning units make a substantial amount of noise during operation. 
         [0009]    There is therefore a need in the art for an improved window-mounted air conditioning unit which addresses some of the shortcomings of presently known devices. 
       SUMMARY 
       [0010]    An air conditioning unit mountable in a window on a wall of a building. The unit includes a front section configured to be disposed inside the building and on a first side of the window; and a rear section configured to be disposed outside the building and on a second side of the window. A duct extends between the front and rear sections and is positioned to be clampingly engaged between the window sill and a bottom end of the lower window. The front section of the unit hangs downwardly away from the sill and is disposed adjacent a first side of the wall. The rear section of the unit hangs downwardly away from the sill and is disposed adjacent a second side of the wall. The duct includes a first duct member which moves cooled air in a first direction towards the inside of the building; and a second duct member which moves return air in a second direction away from the inside of the building. The duct is changeable in length to alter the distance between the front and rear sections so as to accommodate the air conditioning unit&#39;s installation in different windows that are installed in walls of different thickness. 
         [0011]    There is further disclosed a method of installing an air conditioning unit, as described above, in a window defined in a wall of a building. The method comprises the steps of:
       changing the length of the duct which extends between the front section and rear section of the air conditioning unit;   resting the duct on the window sill;   positioning the front section inside the building and adjacent a first side of the wall beneath the window sill;   positioning the rear section outside the building and adjacent a second side of the wall beneath the window sill;   lowering the window so that the bottom end thereof contacts the upper surface of the duct.       
 
         [0017]    The method further includes the step of moving the front and rear sections of the duct towards each other so that the wall is sandwiched therebetween. 
         [0018]    The air conditioning unit is substantially quieter than previously known units. Previously known air conditioning units sit on the window sill, with the mechanical components thereof situated partially within the room or building and partially outside the room or building. The user can therefore readily hear those components operating. The air conditioning unit described herein is contemplated to have substantially all of its mechanical components situated outside of the building. The user will therefore not easily hear these components in operation, particularly because the window is closed, and more particularly because the mechanical components are positioned below the closed window. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]    A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
           [0020]      FIG. 1  is a front elevational view of a window in which is mounted a window air conditioning unit, with the unit being shown from inside a room of a building and looking through the window to a location outside the building; 
           [0021]      FIG. 2  is a perspective view of the air conditioning unit shown removed from the window; 
           [0022]      FIG. 3  is a cross-sectional side view of the air conditioning unit taken along line  3 - 3  of  FIG. 2 ; 
           [0023]      FIG. 3A  is an enlarged cross-sectional view of the highlighted region of  FIG. 3 ; 
           [0024]      FIG. 4  is a top view of the rear end of the air conditioning unit taken along line  4 - 4  of  FIG. 3 ; 
           [0025]      FIG. 5  is a top view of the air conditioning unit taken along line  5 - 5  of  FIG. 3 ; 
           [0026]      FIG. 6  is a front view of the air conditioning unit taken along line  6 - 6  of  FIG. 3 ; 
           [0027]      FIG. 7  is a rear view of the air conditioning unit taken along line  7 - 7  of  FIG. 3 ; and 
           [0028]      FIG. 8  is a cross-sectional side view of the air conditioning unit shown in an expanded condition and installed on a wider wall and window frame than the installation shown in  FIG. 3 . 
       
    
    
       [0029]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows a wall  10  within which is mounted a double-hung window  12  that is surrounded by a frame  14 . Window  12  includes an upper window  12   a  and a lower window  12   b.  Lower window  12   b  may be raised and lowered relative to a window sill  16  ( FIG. 3 ). The window  12  is shown from the perspective of a person looking from inside a room of a building toward the window  12 . If one looks through the window  12   a / 12   b  one will see an area outside of the building.  FIG. 3  shows that wall  10  includes a first side  10   a  that is located inside the room and on a first side of window  12 ; and a second side  10   b  that is located on the outside of the building and on a second side of window  12 . Siding  18  is illustrated as being installed over the second side  10   b  of wall  10 . 
         [0031]    A window-mounted air conditioning unit is installed in window  12  and is generally indicated by the reference character  20 . Air conditioning unit  20  as shown in greater detail in  FIG. 2-7 , comprises a front section  22 , a rear section  24  and an air duct  26  that extends between front and rear sections  22 ,  24 . As best seen in  FIG. 3 , air conditioning unit  20  is generally U-shaped when viewed in cross-section taken from one side of the device; as opposed to the generally square or rectangular configuration of previously known window-mounted air conditioning units. 
         [0032]    Air conditioning unit  20  is installed in window  12  such that front section  22  thereof is retained within the room to be air conditioned, rear section  24  is retained outside of the building, and the air duct  26  extends between the interior and exterior of the building and is the only part of air conditioning unit  20  that is contacted by the lower window  12   b.  In particular, air conditioning unit  20  is secured in window  12  by duct  26  being wedged between the lower window  12   b  and sill  16 . Still further, front section  22  is disposed adjacent and substantially parallel to first side  10   a  of wall  10  and on a first interior side of window  12 . Rear section  24  is disposed adjacent and substantially parallel to second side  10   b  of wall and on a second exterior side of window  12 . Wall  10  is substantially wedged between front and rear sections  22 ,  24 . 
         [0033]    Front section  22  preferably is a generally rectangular member that has a width “W”, a height “H 1 ” and a length “L 1 ”. Duct  26  comprises a first duct  28  and a second duct  30  which are laterally separated from each other by a gap  32 . The overall width of duct  26  is slightly less than width “W”. The height of first and second ducts  28 ,  30  is substantially identical and is indicated as height “H 2 ”. The length of the first and second ducts  28 ,  30 , shown in  FIG. 2 , is length “L 2 ”. As will be described further herein length “L 2 ” is selectively telescopingly adjustable to change the distance between front and rear sections  22 ,  24  and therefore the size of the gap  23  ( FIGS. 2 &amp; 3 ) disposed therebetween. Rear section  24  is also a generally rectangular member that has substantially the same width “W” as front section  22  and is of a height “H 3 ” and a length “L 3 ”. As is evident from  FIG. 2 , the height “H 2 ” of duct  26  is smaller than the height “H 1 ” of front section  22 , which in turn is smaller than the height “H 3 ” of rear section  24 . Thus, unlike presently known air conditioning units (not shown), the overall height of air conditioning unit  20  is not constant between its front end  22   a  and rear end  24   b.  Most advantageously, the height “H 1 ” and length “L 2 ” of front section  22  of air conditioning unit  20  disposed within the interior of the room to be cooled are relatively small in comparison to previously known devices. Additionally, front section  22  is not seated within the space defined by window frame  14 . Instead, a portion of front section  22  hangs downwardly from the lower part  14   a  of frame  14  and sill  16  and is disposed adjacent first side  10   a  of wall  10 . Still further, rear section  24  hangs downwardly from the lower part  14   a  of frame  14  and sill  16 , and is disposed adjacent a second side  10   b  of wall  10 . This arrangement makes it less likely that an installer will loose control of unit  20  during installation. This is because air conditioning unit  20  is generally U-shaped in cross-section and is thereby relatively easily engaged over the top of sill  16  without needing to be precariously balanced in place on top of the sill until engaged by the lower window  12   b.    
         [0034]    Referring to  FIGS. 2 and 3 , front section  22  includes a front wall  22   a,  a rear wall  22   b,  a top wall  22   c,  a bottom wall  22   d,  a first side  22   e,  and a second side  22   f.  Walls  22   a - 22   f  bound and define an interior compartment  34  ( FIG. 6 ). Compartment  34  is divided into upper and lower chambers  34   a,    34   b  ( FIG. 3 ) by an angled interior wall  36 . Front wall  22   a  includes a display screen  38  and control buttons  40  and knobs  42  for activating, setting and monitoring the functioning of air conditioning unit  20 . It will be understood that any desired controls and displays may be provided on front section  22 . Front wall  22   a  further includes one or more vents  44  which are in fluid communication with compartment  34 , most particularly the upper chamber  34   a  thereof. Cooled air is able to exit unit  20  through vents  44 , as will be hereinafter described. 
         [0035]      FIG. 3  shows that bottom wall  22   d  is also provided with a plurality of vents  46 . Vents  46  are in fluid communication with compartment  34 , most particularly the lower chamber  34   b  thereof. Vents  46  are provided for return air from the room to be drawn into air conditioning unit  20 . A filter  48  extends across lower chamber  34   b  of compartment  34  adjacent vents  46  to filter the return air. 
         [0036]    As shown in  FIGS. 3 and 5 , a threaded bolt  50 , with associated washers  52  and nut  54  extends from front wall  22   a  of front section  22  through to front wall  24   a  of rear section  24 . This bolt  50  maintains air conditioning unit  20  at a desired overall length that is determined by setting the length of duct  26 , as will be hereinafter described.  FIG. 2  shows that an electrical cord  56  extends outwardly from front section  22  of air conditioning unit  20  to connect the same to a remote outlet or other source of power (not shown). 
         [0037]    Rear section  24  of air conditioning unit  20  includes a front wall  24   a,  a rear wall  24   b,  a top wall  24   c,  a bottom wall  24   d,  a first side wall  24   e,  and a second side wall  24   f.  A horizontally oriented wall  58  ( FIG. 3 ) divides the rear section into an upper compartment  60  and a lower compartment  62 . Upper compartment  60  is bounded and defined by a first portion of front wall  24   a,  a first portion of rear wall  24   b,  top wall  24   c,  and upper portions of first and second side walls  24   e,    24   f.  An angled wall  64  ( FIG. 7 ) extends between horizontal wall  58  and first side wall  24   de  to create a channel  66  for directing air into first duct  28  as will be hereinafter described. A vertical wall  67  ( FIGS. 3 &amp; 5 ) extends between top wall  24   a  and horizontal wall  58  and divides upper compartment  60  into first and second chambers  60   a,    60   b.  An aperture  69  ( FIGS. 5 &amp; 7 ) is defined in wall  67 . An evaporator  68  and blower  70  are also situated in upper compartment  60  adjacent an exit to second duct  30 . Evaporator  68  is located in first chamber  60   a  and blower  70  is located in second chamber  60   b.  In particular, blower  60   b  is positioned immediately adjacent aperture  69  in wall  67  between first and second chambers  60   a,    60   b.  A first motor  72  is operatively engaged with blower  70  to rotate the same about drive shaft  74  and draw air through second duct  30 , through first chamber  60   a  and move it into second chamber  60   b.    
         [0038]    Lower compartment  62  is bounded and defined by a second portion of front wall  24   a,  a second portion of rear wall  24   b,  bottom wall  24   d,  and lower portions of first and second side walls  24   e,    24   f.  A plurality of vents  76  ( FIG. 7 ) are provided on first side wall  24   e.  Vents  76  are in fluid communication with lower compartment  62  and are provided to draw air from outside of the building and into air conditioning unit  20 . A plurality of vents  78  ( FIG. 3 ) are provided in rear wall  24   b  and these vents  78  are in fluid communication with lower compartment  62 . Vents  78  are provided to permit heated air to exit lower compartment  62  and be released into the environment outside of the building. 
         [0039]    A plurality of components is housed in lower compartment  62 . A condenser  80  ( FIG. 4 ) is positioned adjacent rear wall  24   b  and vents  78 . A compressor  82  is operatively connected to a first end of condenser  80  by a first tube  84 . A second tube  86  ( FIG. 3 ) extends between a second end of condenser  80  and evaporator  68  in upper compartment  60 . A third tube  88  ( FIG. 3 ) extends between compressor  82  and evaporator  68 . A fan  90  is connected by way of a drive shaft  92  to a second motor  94 . Fan  90  is positioned so that the blades  90   a  thereof are spaced a distance from a first region of condenser  80 . It will be understood that instead of air conditioning unit  20  including both of the first and second motors  72 ,  94 , unit  20  may alternatively be configured to include only a single motor which provides power to all of the powered components. In this latter instance, components like fan  90  and blower  70  may be operatively connected together by a drive belt (not shown). It will be understood that there are suitable electrical connections between the remote power outlet and the components within second section  24  but these have not been illustrated in the figures for the sake of clarity. 
         [0040]    As is evident from  FIGS. 4 and 7 , a vertical wall  96  extends between horizontal wall  58  and bottom wall  24   d.  Wall  96  has an opening  98  therein that is substantially circular and is of generally the same diameter as fan  90 . A portion of wall  96  is cut-away in  FIG. 7  to show the compressor  82  and first and third tubes  84 ,  88 . Wall  96  divides lower compartment into front and rear chambers  62   a,    62   b  ( FIG. 4 ). Wall  96  enables the air flow through lower compartment  62  to be redirected as illustrated by the unnumbered airflow arrows in the various figures. 
         [0041]    As indicated previously herein duct  26 , which extends between front and rear sections  22 ,  24 , is comprised of first and second ducts  28 ,  30 . First duct  28  extends between upper chamber  34   a  of front section  22  and second chamber  60   b  of upper compartment  60  of rear section  24 . Second duct  30  extends between lower chamber  34   b  of front section  22  and first chamber  60   a  of upper compartment  60  of rear section  24 . 
         [0042]    Duct  26  is a telescoping duct that is able to be adjusted to change the distance between rear wall  22   b  of front section  22  and front wall  24   a  of rear section  24 . Particularly, duct  26  telescopes to change the size of gap  23  between a first length “L 2 ” ( FIGS. 1-3 ) and a second length “L 4 ” ( FIG. 8 ). Duct  26  is able to move between a first collapsed position where gap  23  has a size “L 2 ” and a second expanded position where gap  23  has a size “L 4 ”. 
         [0043]    Referring to  FIG. 5  there is shown the construction of first duct  28 . First duct  28  is comprised of a first duct member  100  and a second duct member  104  that are telescopingly engaged with each other. First duct member  100  is integral with front section  22  and extends for a distance rearwardly from rear wall  22   b  thereof. First duct member  100  is a tubular sleeve that is generally rectangular in cross-sectional shape and defines a first bore  102  therein. First duct member  100  terminates in an outermost edge  100   a.  Second duct member  104  is integral with rear section  24  and extends for a distance forwardly from front wall  24   a  thereof. Second duct member  104  is a tubular sleeve that is generally rectangular in cross-section shape and defines a second bore  106  therein. Second duct member  104  is sized so as to be receivable within the bore  102  of first duct member  100 . Second duct member  104  terminates in an outermost edge  104   a.  Seals  108  are provided between the interior surface of first duct member  100  and the exterior surface of second duct member  104 . Seals  108  preferably are secured to the second duct member  104 . Air flows through bore  106  of second duct member  104  when air conditioning unit  20  is operated. 
         [0044]    In a similar fashion, second duct  30  is constructed of a third duct member  110  and a fourth duct member  112  that are telescopingly engaged with each other. Third duct member  110  is integral with front section  22  and extends for a distance rearwardly from rear wall  22   b  thereof. Third duct member  110  is a tubular sleeve that is generally rectangular in cross-sectional shape and defines a third bore  114  therein. Third duct member  110  terminates in an outermost edge  110   a.  Fourth duct member  112  is integral with rear section  24  and extends for a distance forwardly from front wall  24   a  thereof. Fourth duct member  112  is a tubular sleeve that is generally rectangular in cross-sectional shape and defines a second bore  116  therein. Third duct member  110  is sized so as to be receivable within the bore  116  of fourth duct member  112 . Fourth duct member  112  terminates in an outermost edge  112   a.  Seals  118  are provided between the interior surface of fourth duct member  112  and the exterior surface of third duct member  110 . Seals  118  preferably are secured to third duct member  110 . Air flows through third bore  114  of third duct member  110  when air conditioning unit  20  is operated. 
         [0045]    Air conditioning unit  20  is installed and used in the following manner. The installer will first measure the thickness of wall  10  to determine how great a length to set duct  26  at for installation. This is accomplished by measuring the distance “D 1 ” between the innermost part of window  12  or wall  10 , and the outermost part window  12  or wall  10 .  FIG. 3  shows that this distance “D 1 ” is measured between an interior surface  15  of window frame member  14   a  and the outermost edge  16   a  of sill  16 . Duct  26  is then adjusted in length to initially be longer than distance “D 1 ” so that unit  20  may be easily positioned in the open window  12 . Duct  26  is adjusted by rotating bolt  50  in a first direction to loosen the engagement of front and rear sections  22 ,  24  and this causes the length of the shaft  50   a  ( FIG. 5 ) between nut  54  and bolt  50  to increase, thereby increasing the size of gap  23 . (Conversely, when bolt  50  is rotated in a second direction, the length of the shaft  50   a  between nut  54  and bolt  50  is decreased and front and rear sections  22 ,  24  are drawn towards each other closing the size of the gap  23 .) When bolt  50  is sufficiently loosened, the installer will pull front and rear sections  22 ,  24  away from each other in the direction of arrows “A” ( FIG. 2 ) to increase length “L 2 ” so that it is greater than distance “D 1 ”. This pulling motion causes a length of second duct  104  to be pulled outwardly from within the bore of first duct  100  so that end  100   a  of first duct  100  is moved a distance away from second section  24 . Simultaneously, a length of third duct  110  is pulled outwardly from within the bore of fourth duct  112  so that end  112   a  of fourth duct  112  is moved a distance away from front section  22 . The arrangement ensures that substantially the same length of duct is pulled outwardly in an even, smooth motion from the bores of the first and fourth ducts  100 ,  112 . Alternatively, if the movement is in the opposite direction, the arrangement ensures that the motion of pushing front and rear sections  22 ,  24  toward each other is a smooth, even or non-skewed motion. The arrangement ensures that rear wall  22   b  of front section  22  remains substantially parallel to front wall  24   a  of second section  24  at all times. 
         [0046]    Air conditioning unit  20  is then positioned in the space created by raising lower window  12   b  away from bottom frame member  14   a.  Unit  20  is positioned so that front section  22  is disposed inside the room and adjacent first side  10   a  of wall  10 , and second section  24  is disposed outside of the building and adjacent second side  10   b  of wall  10 . Additionally, bottom surface  26   a  of duct  26  contacts and rests upon sill  16 , or upon the uppermost regions of bottom window frame  14   a.  When unit  20  is resting in this position the bolt  50  is rotated in the second direction to draw front and rear sections  22 ,  24  toward each other in the opposite direction of arrow “A”. This motion is continued until rear wall  22   b  of front section  22  is adjacent the interior surface  15  of window frame member  14   a  or first side  10   a  of wall  10 ; and front wall  24   a  of second section  24  is adjacent the outermost exterior surface of sill  16  or second side  10   b  of wall  10 . Thus, wall  10  is sandwiched between front and rear sections  22 ,  24 . Window  12   b  is then lowered so that a lower end  13  thereof contacts upper surface  26   b  of duct  26 . Duct  26  is therefore clampingly retained between lower end  13  of window  12  and sill  16 . At this point, gravity and window  12   b  keep unit  20  in place. Any tendency of unit  20  to rotate and drop out of window  12  to the outside of the building is resisted because front section  22  somewhat counterbalances the weight of second section  24 . It should be noted that the same installation method applied to installing unit  20  into a window having a greater wall thickness “D 2 ” as illustrated in  FIG. 8 . 
         [0047]    At this point, a small gap  51  ( FIG. 1 ) is defined on either side of unit  20  and between bottom end  13  of window  12 , window frame  14  and sill  16 . Unit  20  preferably is provided with baffles  53  to block gap  51  so as to prevent mixing of air within the building with the air disposed outside the building. Alternatively, baffles  53  may be replaced with foam blocks or other similar obstructions to close off gap  51 . It should also be noted that when unit  20  is installed, a spacer foot  55  ( FIG. 3 ) mounted on rear wall  22   b  of front section  22  contacts the front surface of first side  10   a  of wall  10  and keeps front section  22  in an orientation where it is substantially parallel to first side  10   a  of wall  10 . 
         [0048]    Once unit  20  is safely installed in window  12 , control buttons  40  and knobs  42  are then engaged to switch unit  20  on to cool the air within the interior the room. Unit  20  substantially functions in all other ways in the same manner as known air conditioning units to cool and circulate air. The rotation of fan  90  and blower  70  is indicated by arrows “B” and “C” respectively in  FIG. 7 . The airflow through air conditioning unit  20  is illustrated by way of the unlabeled arrows shown throughout the figures. Suffice to say to that return air is taken into air conditioning unit  20  from the room through vents  46  and cool air is expelled into the room through vents  44 . Furthermore, air is drawn into the second section  24  of air conditioning unit from the air outside the building, through vents  76  and is expelled from second section  24  and into the air surrounding the building through vents  78 . 
         [0049]    A method of installing an air conditioning unit  20  in a window  12  defined in a wall  10  of a building comprises the steps of:
       changing the length of duct  26  extending between front section  22  and rear section  24  of the air conditioning unit  20 ;   resting duct  26  on window sill  16 ;   positioning front section  22  inside the building and adjacent a first side  10   a  of wall  10  beneath the window sill;   positioning rear section  24  outside the building and adjacent a second side  10   b  of wall  10  beneath the window sill;   lowering window  12  so that bottom end  13  thereof contacts upper surface  26   b  of duct  26 .       
 
         [0055]    The method further includes the step of moving front and rear sections  22 ,  24  of duct  26  towards each other so that wall  10  is sandwiched therebetween. 
         [0056]    It will be understood that while the air conditioning unit has been described above as being mountable within a window of a building, it may alternatively be mounted through a hole in the wall of the building in a location free of a window. In this instance, the duct  26  will be positioned in the hole in the wall and the front and rear sections  22 ,  24  will be on opposite sides of the wall. The hole in the wall would be cut to be substantially equal in size to duct  26 . The through bolt  50  could be removed and the unit would be installed in two pieces, with the front  22  being on an inside of the wall and the rear  24  being on an exterior side of the wall. Once the front and rear  22 ,  24  have been matingly engaged together via duct  26  being inserted through the hole in the wall, the through bolt  50  could be reinstalled to hold front  22  and rear  24  together. The term “window” should therefore be interpreted to mean any suitably sized hole or aperture defined in a building wall, whether a window frame and sheet of glass mounted in that frame are present on not. 
         [0057]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0058]    Moreover, the description and illustration of the invention are an example and the invention is not limited to the exact details shown or described.