Abstract:
An adjustable screen re don system is presented. The present invention screen retention system comprises a mesh Of perforate screen retained within a frame composed of frame members have channel cross sections. The screen is formed with a rolled or U-shaped edge hem. The edge hem having a free edge that folds inwardly over the inner face of the screen and is parallel to, and spaced above, the inner face of the screen. The framing members are channel section extrusions which contain features for retaining, tensioning and locking the screen. The adjustable screen retention system herein presented improves upon the prior art by providing a more secure attachment of the screen within the channel of the frame members thereby providing increased resistance to screen impact loading. The new system also provides for a broader range of screen of tensioning adjustment than has heretofore been available and further electrically isolates the screen from the walls of the channel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to screens for windows, doors and the like, and in particular, to a screen retention assembly for securing a screen to a frame or surround. The invention presented is primarily intended for security screens that deter human intruders and provide impact protection from flying debris. However, the system may also be used for security screens that prevent the intrusion of insects and small animals into a building. 
         [0003]    2. Background of the Invention 
         [0004]    Doors or windows incorporating a semi-transparent screen or mesh provide the advantages of visibility, ventilation, and also the ability to prevent the passage of insects or small animals through the aperture covered by the screen. Screens are typically made from a flexible wire mesh although other flexible or semi-rigid perforate sheet materials may be used. 
         [0005]    Common prior art screen systems attach the mesh directly to the perimeter of the window or door opening with simple fasteners such as screws, rivets or glue. While such systems are functional, they lack a means of applying tension to the screen upon installation. A tensioned screen is important because ordinary use of a door or window often causes repeated impact loads to the screen, for example pushing the door open by pushing or kicking the screen. Thus, the semi-rigid material of the screen often appears floppy after a short period of ordinary use. 
         [0006]    The strength and appearance of a screen attached using simple fasteners is also overly dependent on the skill of the fabricator. For example, if the screen is cut slightly too small, the screen will be weakened and subject to pulling out of the frame because the fasteners will be too close to the edge of the mesh. If glue is used, it will not sufficiently cover enough surface area of the mesh to create a strong bond. On the other hand, if the screen is cut slightly to large, then the mesh will be unavoidably floppy because the use of simple fasteners provide no means for tensioning the mesh. 
         [0007]    To overcome many of the weaknesses of directly fastening a screen to the perimeter of a window or door opening, more modern systems that frame the openings with extruded metal, typically aluminum, channel sections have been developed, wherein the edges of the screen are secured within the channel walls. A wide variety of means for securing screens within the channel walls have been developed. Prior art systems range from simple friction fits between the screens and the channels to complex turnbuckle like fasteners mounted in the channels which grip and tension the screen. 
         [0008]    Screen retention systems that feature channel section frames about the perimeter of door or window opening have effectively overcome many of the drawbacks of systems that attached the screen directly to the door or window frame. Aesthetic appearance has been improved due to the lack of visible fasteners. Function has also been improved because some of the prior channel section screen retention systems have some ability to tension the screen. 
         [0009]    Prior an channel-based screen retention systems do suffer from certain drawbacks however. In particular, prior art systems typically use flat or screen edges which allow for only a very limited amount of screen tensioning and offer only modest resistance to screen impact loading. When screen tensioning provisions are specifically provided, they nevertheless often have a very limited adjustment range. In addition, many prior art screen retention systems allow the metal of the screen, typically iron or steel, to contact the wall of the, typically aluminum, channel. This contact of dissimilar metals allows for galvanic corrosion at the interface between the screen and the channel. Power coated stainless steel is the preferred material for security screens. Common insect screens are typically made using vinyl coated fiber glass, aluminum mesh, galvanized steel, bronze, stainless steel, or vinyl coated polyester. 
         [0010]    What is needed in the art is an improved channel-based screen retention system that provides a more secure attachment of the screen within the channel to provide increased resistance to screen impact loading. Also desirable is a broader range of screen of tensioning adjustment and for a design that electrically isolates the screen from the walls of the channel, when the channel and screen are both made from metallic materials as is commonly the case. 
       SUMMARY OF THE INVENTION 
       [0011]    It is the purpose of the present invention to provide an improved channel-based screen retention system that increases the resistance to screen impact loading; provides for a broad range of screen tensioning adjustability, and that electrically isolates the screen from the walls of the channel to prevent galvanic corrosion, among other features. 
         [0012]    The invention comprises a screen retention system comprised of a screen retained within a frame, the frame being composed of frame members having channel cross sections. In the exemplary embodiment, the frame members are extrusions, the outer perimeter of which frame a window, door, or like structure, or are designed to be received within the opening of a door, window, or like structure, where it is desired to close out the opening with a screen. The mesh or perforate screen features an inner face and an outer face. The perimeter of the screen is formed with a rolled or u-shaped edge hem. The edge hem having a flange which folds inwardly over the inner face of the screen and is parallel to, and spaced above, the inner face of the screen. 
         [0013]    The inner perimeter of the members which form the frame for the screen include an opening or main channel for receipt of the screen. In cross section, an upper interior wall of the main channel of each frame member has a serrated surface while an opposing lower, interior wall features a pair of spaced apart inner and outer interior longitudinal channels. The interior longitudinal channels serve to secure an elastomeric gasket. A substantial depth of clear space exists inwardly of the serrations and a bottom of the main channel. The depth of free space allows for a broad range of adjustability for tensioning the screen. 
         [0014]    The elastomeric gasket features a pair of spaced apart, longitudinally running per and lower ribs featuring a bulb style cross section for engagement with the mating spaced apart inner and outer interior longitudinal channels formed in the lower interior wall of the main channel of the frame members. On an opposite side, the elastomeric gasket has serrations for engaging the mesh or perforations of the screen. The screen is inserted into the channel sections such that the u-shaped hem of the screen faces away from the serrations in the elastomeric gasket. 
         [0015]    The screen is locked into place within the channel of the frame members by means of a plurality of locking tabs. In the exemplary embodiment, the locking tabs are of generally rectangular cross-section and are composed of a deformable material. One face of the tabs includes serrations. During assembly, the locking tabs are inserted into the channel of the frame members between the inner face of screen and the upper interior wall of the channel. The screen is locked into place and tensioned by pressing the locking tabs downwardly into the channel such that the serrated face of the tabs engages the serrations on the upper interior wall of the channel while a perpendicular face of the tabs engages an upper edge of the flange of the u-shaped hem on the screen. The degree of screen tension is controlled by the insertion depth of the tabs. During tab insertion the fixed elastomeric gasket beneath the screen mesh is compressed and provides a constant force to hold the tabs in position. 
         [0016]    After the screen has been secured within the channel of the frame members as described above, an elastomeric gasket is partially inserted into the opening between the inward face of the screen and the upper interior wall of the channel for the purpose of sealing out the elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a perspective view of a framed screen for closing out an aperture; 
           [0018]      FIG. 2  is a partial side sectional view through the line A-A of  FIG. 1 , showing the components of an adjustable screen retention assembly in accordance with an illustrative embodiment of the present invention, showing the main channel, screen, retention gasket, locking tab(s) and sealing gasket, among other features. 
           [0019]      FIG. 3  is a partial side sectional view through the line A-A of  FIG. 1 , showing the components of an adjustable screen mention assembly in accordance with the illustrative embodiment of  FIG. 2 , with the sealing gasket removed. 
           [0020]      FIG. 4  is a partial side sectional view through the line A-A of  FIG. 1 , of the components of an adjustable screen retention assembly in accordance with the illustrative embodiment of  FIG. 2 , with the outer sealing gasket, screen and locking tabs removed. 
           [0021]      FIG. 5  is a partial side sectional view of the screen used in the illustrative embodiment of the adjustable screen retention assembly of  FIG. 2 . 
           [0022]      FIG. 6  is a cross sectional view of the locking to shown in the illustrative embodiment of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
         [0024]    With reference to  FIG. 1 , there is illustrated a screen retention system  10  having a frame  12  comprised of elongate frame members  14  having channel cross sections  18  with a mesh or perforate screen  16 , attached to the frame members  14 . The screen  16  covers the opening enclosed by the frame  12 . In the exemplary embodiment of  FIG. 1 , the screen retention system  10  is shown as having a discrete frame  12 , the outside perimeter of which is sized to fit within an opening in a door, wall or other structure having an aperture. It should be understood however, that the present invention is net limited to a discrete frame or any particular style or shape of frame. In alternative embodiments, the frame  12  may form the primary structural frame for a door, window inset in a wall, or other structure where an aperture is desired. 
         [0025]    With reference to  FIGS. 2-4 , the cross-section  18  of the channel of the frame members  14  of the screen retention system  10  of the present invention is depicted along with the screen  16 , screen retention or retaining gasket  20  at least one locking tabs  22  and sealing gasket  24  which comprise the major components of the screen tensioning system  10 . 
         [0026]    Referring now to  FIG. 5 , the mesh or perforate screen  16  features an inner face  26  and an outer face  28 . The perimeter of the semen  16  is formed with a rolled or u-shaped edge horn  30 . The edge hem  30  has a flange  32  which folds inwardly over the inner face  26  of the screen  16  and is parallel to, and spaced above, the inner face  26  of the screen  16 . The screen  16  may be made from a wide variety of mesh or perforate materials. Wire mesh made from virtually all plastically deformable metallic materials including steel, iron, and aluminum, among others, is suitable. Wire mesh made from type 304 stainless steel is one particularly preferred screen material. Perforate plastic sheet materials that can be formed with the edge hem  30  or its functional equivalent, are also suitable. A stepped surface around the border of a plastic sheet material would be the functional equivalent of the edge hem  30  in a wire mesh material 
         [0027]    Referring now to  FIGS. 2-4 , the channel  18  of the frame members  14  features an upper interior wall  36  and a lower interior wall  38 . The upper interior wall  36  includes a serrations  40  for engaging the at least one locking tabs  12 . The opposing lower interior wall  38  features a pair of spaced apart inner  44  and outer  42  lower interior longitudinal channels. The lower interior longitudinal channels  42  and  44  serve to receive and retain the semen retention gasket  20 . The inner  44  and outer  42  lower interior longitudinal channels both feature inwardly facing retaining flanges  48  (see  FIG. 4 ), which serve to capture and retain inner longitudinal ribs  50  and  52  of the screen retaining gasket  20 . The inner and outer longitudinal ribs  50  and  52  have a bulb-style cross section  51  which is retained by the inwardly facing retaining flanges  48 . A substantial depth of free space  46  (see  FIG. 4 ) exists inwardly of the lowermost of the serrations  40  and a bottom surface  54  of the channel  18 . The depth of the free space  46  allows for a broad range of adjustability with respect to tensioning the screen  16 . The framing members  14  may be made from a variety of metallic and plastic materials. One exemplary preferred material is extruded aluminum. 
         [0028]    Referring to  FIG. 4 , the screen retention gasket  20  features the spaced apart, longitudinally miming upper  50  and lower  52  ribs with a bulb-style cross section  51  on an inner face  56  of the gasket  20  for engagement with the spaced apart inner  42  and outer  44  lower interior longitudinal channels formed in the lower interior wall  38  of the cross-section  18  of the framing members  14 . On an opposite outer face  58  of the gasket  20  are serrations  60  for engaging the mesh of the screen  16 . The screen  16  is inserted into the channel section  18  such that the u-shaped hem  30  of the screen faces away from the serrations  60  in the retaining gasket  20 . The screen retention gasket  20  may be made from a variety of elastomeric materials as well as deformable plastic materials. 
         [0029]    The screen  16  is locked into place within the channel section  18  of each frame member  14  by means of the at least one locking tabs  22 . Referring now to  FIG. 6 , in the exemplary embodiment, the at least one locking tabs  22  are of generally rectangular cross-section having a serrated upper face  62  and a planar lower face  63 , as well as planar edge faces  64 . In the exemplary embodiment, the at least one locking tabs  22  and are composed of a deformable material. 
         [0030]    Referring now to  FIGS. 2-4 , during assembly, the at least one locking tabs  22  are inserted into the channel  18  between the inner face  26  of the screen  16  and the upper interior wall  36  of the channel  18 . The screen  16  is locked into place and tensioned by pressing the at least one locking tabs  22  downwardly into the channel  18  such that the serrated upper face  62  of the at least one locking tabs  22  engages the serrations  40  on the upper interior wall  36  of the channel  18  while one of the perpendicular edge faces  64  of the at least one locking tabs engages the upper edge  34  of the flange  32  of the u-shaped hem  30  of the screen  1 . The planer lower face  63  of the at least one locking tabs  22  abuts the interior face  26  of the screen  16 . The degree of screen tension is controlled by the insertion depth of the at least one locking tabs. The free space  46  of the channel  18 , provides clearance for the hem  30  of the screen  16  to be pressed downwardly within the free space  46  and therein allows for screen tension adjustability. 
         [0031]    In the exemplary embodiment, the serrations  40  of the upper interior wall  36  of the channel  18  are made from a material comparatively harder than that of the at least one locking tabs  22  to ensure that the serrations  40  of the channel  18  engage and plastically deform the mating serrations  62  the locking tabs  22 . The material of the retention gasket  20  is comparatively softer than that of the screen  16 , such that the serrations  60  of the gasket  20  engage with the mesh or perforations  15  in the screen  16 . 
         [0032]    After the screen  16  has been secured within the channels  18  of the frame members  14  as described above, an elastomeric sealing gasket  24  is partially inserted into the opening between the inward face of the screen  16  and the upper interior wall  36  of the channel  14  for the purpose of sealing out the elements. 
         [0033]    The above described screen retention system  10  presents several advantages over the prior art. In particular, the free edge  34  of the screen  16  does not require the addition of an electrical insulator because the at least one locking tabs  22  are themselves made (in the exemplary embodiment) from an insulating material, but more importantly the free edge  34  of the screen  16  does not face toward the dissimilar metal (in the exemplary embodiment aluminum) of the upper and lower interior walls  36  and  38  of the channel  18  of the frame members  14 , but instead faces toward one of the planer edge faces  64  of the at least one locking tabs  22 , thereby preventing dielectric corrosion. 
         [0034]    In addition more force can be applied to edge hem  30  of the screen  16  of the present invention without distortion of free edge  34  during tensioning of the screen  16 , as compared to, for example, a perpendicular lip as may be found in some prior art designs. This is important because a more highly tensioned screen  16  improves the aesthetics of the finished product, and for security screen applications can withstand greater impact due m it&#39;s improved pullout strength. The screen  16  of the present invention  10  may also be more centrally located within the frame  12  preventing an imbalance of the sealing gasket  24  and retention  20  gasket thicknesses, which further contributes to improved appearance. The screen&#39;s  16  tension is maintained by compressive force from the retention gasket  20 , holding serrated surface  62  of the at least one locking tab  22  into the matching serrations  40  of the upper interior wall  36  of the frame members  14 . The screen retention gasket  20  has a high degree of compressibility which allows for the use of screens of different thickness (wire thicknesses in the case of wire mesh screens) without the need to use gaskets of differing thicknesses. 
         [0035]    Also, the edge hem  30  of the screen  16  of the present invention has manufacturing advantages over the L-shaped edge hem used in some prior an designs in that formed screens can be stacked after the formation of edge hem  30  without risk of damage to the protective finish of adjacent screens  16 , as the free edges  34  of the screen are parallel to the plane of the screen. Screens featuring the U-shaped edge hem  3  of the present invention can be more easily guided into frame members having a narrow opening without risk of damage to the semen doe to the rounded edge profile as compared to the abrupt square or sharp edge of an L-shaped edge hem design. Further manufacturing efficiency is realized due to the fast installation of the tabs as compared to tensioning with a multitude of fasteners. 
         [0036]    The foregoing detailed description and appended drawings are intended as a description of the presently preferred embodiment of the invention and are not intended to represent the only forms in which the present invention may be constructed and/or utilized. Those skilled in the art will understand that modifications and alternative embodiments of the present invention which do not depart from the spirit and scope of the foregoing specification and drawings, and of the claims appended below are possible and practical. It is intended that the claims cover all such modifications and alternative embodiments.