Abstract:
An insect screen comprised of knitted synthetic yarns and having a knitted pattern incorporated therein. First and second groups of yarns, such as polypropylene, are knitted with the first group of yarns forming a grid or mesh while the second group of yarns form a pattern. Once the insect screen is knitted, the insect screen is subjected to a finishing operation. In finishing the insect screen is stretched and placed in tension using selvages formed of a third group of yarns. The tensioned insect screen is heated causing the yarns to at least slightly plasticize and causing heat fusion of at least some stitches. Thereafter the insect screen and yarns are cooled, resulting in the insect screen becoming more rigid and generally assuming the stretched configuration in the absence of stretching.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to insect screens. 
       BACKGROUND OF THE INVENTION 
       [0002]    Insect screens are widely used in windows, doors, porches, gazebos and the like. No one will argue that insect screens are not functional. Whether they are used in doors, windows or screened porches, insect screens make certain areas of a home habitable and enjoyable, especially during summer months and in areas where insects are prevalent. 
         [0003]    Aside from functionality, little can be said for insect screens. They are not particularly aesthetically pleasing, nor are they even designed to be. But yet, insect screens are often used in and around areas of the home where a great deal of time and attention has been devoted to design and aesthetics. 
         [0004]    Therefore, there is a need for a “designer type” insect screen, one that will not only fit in with fine or even extraordinary furnishings and interior design, but one that will even compliment and add to the aesthetics of a home. 
       SUMMARY OF THE INVENTION 
       [0005]    A knitted insect screen is provided with a pattern incorporated into the insect screen. 
         [0006]    In one particular embodiment, the insect screen is knitted from at least two groups of yarn. The first group of yarns forms a grid or mesh while the second group of yarns is knitted into a pattern that extends over an area of the insect screen. 
         [0007]    Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1  is a front elevation view of an insect screen in a window. 
           [0009]      FIGS. 2A and 2B  are lapping diagrams for mesh yarn inlays. 
           [0010]      FIG. 2C  illustrates lapping diagrams for pillar stitched mesh yarns. 
           [0011]      FIG. 2D  illustrates the combination of yarn inlays and pillar stitched yarns of  FIGS. 2A and 2B . 
           [0012]      FIG. 2E  illustrates patterning yarns showing pillar stitching in non-non-patterned areas and tricot stitching across two wales in patterned areas. 
           [0013]      FIG. 2F  illustrates patterning yarns showing pillar stitching in non-non-patterned areas and tricot stitching across three wales in patterned areas. 
           [0014]      FIG. 2G  illustrates patterning utilizing the patterning yarns of  FIGS. 2E and 2F  superimposed. 
           [0015]      FIG. 3  is a threading diagram and stitch construction for an insect screen fabric using a 3 needle/3 needle technique. 
           [0016]      FIG. 4  is a threading diagram and stitch construction for an insect screen fabric using a 2 needle/3 needle technique. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    With further reference to the drawings, the insect screen of the present invention is shown therein and indicated generally by the numeral  100 . Insect screen  100  is of a general mesh or grid construction. Integrated into the insect screen  100  is a pattern indicated generally by the numeral  101 . Pattern  101  can include individual patterns spaced apart on the insect screen  100 , as illustrated in  FIG. 1 , or can include one continuous pattern that extends over a substantial portion of the insect screen. Various patterns  101  can be incorporated. Typical examples of patterns are palm trees, leaves, landscapes, etc. Generally, insect screen  100  can be used in a wide variety of areas. For example, insect screen  100  can be used in doors, windows, porches, gazebos and other areas where desirable to prevent the ingress of insects. In the example shown in  FIG. 1 , the insect screen  100  is incorporated into a window frame  100 A. 
         [0018]    Insect screen  100  is of a knit construction. Yarns, such as synthetic yarns, are knitted together to form the basic mesh or grid construction as well as the pattern  101 . Basically, at least two groups of yarns are utilized to form insect screen  100 . A first group of yarns is knitted together to form the mesh or grid. This first group of yarns is sometimes referred to as mesh yarns. The mesh or grid can assume various shapes. Typically the mesh or grid will include tiny rectangular openings formed between yarns. In addition to the first group of yarns, or the mesh yarns, there is also a second group of yarns utilized to form pattern  101  that visually contrasts with the mesh or grid. These yarns may be referred to as patterning yarns. 
         [0019]    The two groups of yarns may be of the same color or shade. Alternatively, each group may include yarns of different or distinct colors or shades from the yarns of the other group. For example, the mesh yarns could be clear polypropylene yarns while the patterning yarns could be colored yarns or yarns that are more nearly opaque or black. This provides an additional visual contrast between the mesh or grid and pattern  101 . Similarly, the two groups of yarns may be selected to exhibit other properties. such as composition, denier, ply, etc., that are different in one group than in the other group. 
         [0020]    In the example shown in  FIG. 1 , insect screen  100  includes non-patterned areas  102  and patterned areas  104 . In the non-patterned areas  102 , the patterning yarn lies generally adjacent the mesh yarn. Thus, in the non-patterned areas, the mesh or grid is formed by both the mesh yarn and the patterning yarn. In patterned areas  104 , the patterning yarn is diverted from the mesh yarn to form pattern  101 . In a general sense the patterning yarn is extended across mesh or grid openings so as to partially close selected openings. This gives rise to a pattern effect. 
         [0021]      FIGS. 2A-2G  illustrate sequentially the basic construction of the insect screen  100 . Each of  FIGS. 2A-2G  illustrate the same 10 course (C 1 -C 10 ) by 5 wale (W 1 -W 5 ) portion of insect screen  100  showing the dispositions of the various yarns used in forming the screen. A single course indicates the instantaneous location of the knitting machine needle array while forming screen  100 . Each wale indicates the sequence of locations of a particular needle in the needle array during the formation of screen  100 . A first group of yarns, referred to as the mesh yarns, include an array of zigzag yarns that zigzag back and forth across wales and along courses forming inlays  33  and  34 , as shown in  FIGS. 2A and 2B . The mesh yarns also include an array of connecting yarns that form connecting stitches  32  as shown in  FIG. 2C . Connecting stitches  32  bind the zigzag yarns together. 
         [0022]    The zigzag yarns comprise two sub-groups of yarns. The two sub-groups of zigzag yarns form opposing inlays, one as illustrated in  FIG. 2A  and the other as illustrated in  FIG. 2B . Once the zigzag yarns are connected by the connecting yarns, it follows that tiny openings within the formed mesh are defined. In one example, the connecting yarns form pillar stitches  32  at selected locations to bind the zigzag yarns together, which in turn forms the mesh. 
         [0023]    In forming the mesh or grid, the zigzag yarns of one sub-group extend across a predetermined number of courses along a wale and then turn and extend across a predetermined number of wales to the next course, and thereafter continue to extend along wales and courses in alternating fashion. For example, as shown in  FIG. 2A , one of the zigzag yarns lies below needle location C 1 -W 3 , extends around the needle location to the left, extends along wale W 3  to needle location C 3 -W 3 , turns and extends out of wale W 3  and across wale W 4  to needle location C 4 -W 5 . A zigzag yarn may, in some embodiments, start in every wale in course C 1  and zigzag along wales and across courses in this manner, as illustrated in  FIG. 2A . The zigzag yarns of the other sub-group are inlayed in opposition as can be seen by comparing  FIGS. 2A and 2B . For example, in  FIG. 2B , one of the zigzag yarns lies below needle location C 1 -W 3 , extends to the right of the needle location, extends along wale W 3  to needle location C 3 -W 3 , and then turns and extends out of wale W 3  and across wale W 2  to needle location C 4 -W 1 . Thus, one sub-group of zigzag yarns forms inlays  33  that are open to one side, and the other sub-group of the zigzag yarns forms inlays  34  that are opposed and open to the opposite side. However, when the two inlays are superimposed, as occurs in the knitting process, the side openings are effectively closed to form the mesh and the tiny openings are bounded by the zigzag yarns. 
         [0024]      FIG. 2D  shows the yarn layout when inlays  33  and  34  and pillar stitches  32  are superimposed. The mesh or grid is clearly apparent in that each opening is bounded by a vertical element  105 V and a horizontal element  105 H. Vertical elements  105 V are formed by pillar stitches  32  and portions of inlays  33  and  34  which run within each wale. Horizontal elements  105 H are formed by the portions of inlays  33  and  34  that extend out of wale from one course to another course. 
         [0025]    Inlays  33  and  34 , may, as illustrated in  FIGS. 2A and 2B , be repeated in every wale or they may be spaced apart one or more wales. Connecting yarns form stitches  32  along every wale in which a zigzag yarn turns around a needle location. In one embodiment, illustrated in  FIGS. 2A and 2B , zigzag yarns form inlays  33  and  34  that are immediately adjacent one another, and the connecting yarns form pillar stitches  32  extending along every wale and connecting to the zigzag yarns at every needle location. 
         [0026]    The size of the tiny openings in the mesh can be varied in several ways. For example, the size of the openings can be varied by varying the needle spacing or varying the length of the in wale run of the zigzag yarns. 
         [0027]    The patterning yarn, or second group of yarns, is incorporated into insect screen  100  in two different ways as illustrated in  FIGS. 2E-2G . First, in non-patterned areas  102 , the yarns of the second group tend to follow the connecting yarns of the first group. That is, in non-patterned areas  102 , the yarns of the second group extend alongside the connecting yarns of the first group, and also form pillar stitches  31 A and  31 B. Thus, in non-patterned areas  102 , the yarns of the second group, or the patterning yarns, cooperate with the yarns of the first group to form the mesh or grid. However, in patterned areas  104 , the yarns of the second group are diverted to form a pattern or series of patterns. Effectively, the patterning yarns are diverted such that they extend across openings in the mesh or grid, and at least partially close these openings such that when a substantial area of the screen  100  is viewed a pattern  101  is seen. When the second group of yarns is diverted for the purpose of forming the pattern  101 , they are attached to other yarns in the insect screen  100  by tricot stitches  31 AP and  31 BP. 
         [0028]    The yarns utilized in producing insect screen  100  may be beam or creel fed. Generally, yarns used to form stitches which consume approximately equal amounts of yarn continuously may be beam fed. That is, such yarns would be wound on the beam together ad fed generally uniformly from the beam. Yarns forming stitches or inlays with varying consumption rates during the knitting process are generally creel fed. Each yarn is supplied from a separate spool housed in the creel and fed from there to the knitting machine. Creel feeding such yarns prevents distortion of the grid or mesh structure of insect screen  100 . 
         [0029]      FIG. 3  illustrates one embodiment the insect screen  100  constructed by warp knitting on a Piezo Jacquard machine equipped with a fall plate and employing the 3 needle/3 needle inlay technique. The machine gauge is 12 needles per inch. The stitch construction, indicated generally by the numeral  30 , shows a representative portion of screen  100  showing non-patterned areas  102  and patterned areas  104 . The yarns and threading thereof utilized in forming screen  100  are illustrated in the threading diagram, indicated generally by the numeral  50 . The stitch construction  30  that forms screen  100  illustrates the stitches and their relationships in the fabric that forms the screen  100 . 
         [0030]    Insect screen  100  comprises a generally rectangular mesh or grid structure formed along courses C 1 -C 11  and across wales W 1 -W 9 . Patterned areas  104  are yarn structures that are integrated with the mesh or grid structure to form an aesthetic appeal while maintaining functional attributes. Non-patterned areas  102  comprise the grid or mesh structure. The 3 needle/3 needle inlay technique provides relatively high width stability to the mesh or grid structure of insect screen  100 . For this embodiment, the openings in the grid or mesh structure are spaced approximately 14 openings per inch. 
         [0031]    As mentioned before, yarns used to form insect screen  100  may be of various types, including synthetic yarns. In one embodiment, the yarns are polypropylene yarns, specifically 1/70/36 HESR 100% polypropylene solution dyed. A first group of yarns is utilized uniformly throughout the fabric to form the mesh or grid structure. Yarns of a second group are aligned with and form a part of the mesh or grid structure in non-patterned areas  102 , but are diverted in patterned areas  104  to form the pattern or patterns structures. In one embodiment the yarns of the second group would preferably be creel fed so as to have little or no distortion of the mesh or grid structure. Yarns  52 ,  53 , and  54  comprise the first group of yarns and are guided by ground guide bars L 2 , L 3 , and L 4 , respectively, to form the grid or mesh structure. Yarns  51 A and  51 B comprise the second group of yarns, guided by Jacquard guide bar L 1 A, L 1 B to alternately align with the mesh or grid in non-patterned areas  102  and selectively divert in patterned areas  104  to form pattern  101 . As is appreciated by one of ordinary skill in the art, the guide bars are functional elements of a warp knitting machine that engage needles to form the various stitches and inlays to comprise the structure of a knitted fabric. Selectively diverting yarns  51 A and  51 B is effected by shifts of certain individual guides of Jacquard L 1 A and L 1 B using the piezo capability of the Jacquard. 
         [0032]    Turning now to a more detailed description of stitch construction  30  for the exemplary insect screen  100  of  FIG. 3 , the fabric is formed utilizing several stitch trajectories. Yarn  54  forms inlay  34  spanning 3 needle locations, and yarn  53  forms an opposed inlay  33  likewise spanning 3 needles. This 3 needle/3 needle inlay technique provides relatively high width stability to the grid or mesh structure. Both inlay  33  and inlay  34  each span three wales, or needle locations. For example, yarn  54 , guided by guide bar L 4 , laps to the right about needle position C 1 -W 3 , then back to the left to lap C 2 -W 1 , then to the right to lap C 2 -W 1 , then to the left to lap C 3 -W 1 , and finally to the right to C 5 -W 3 . Inlay  34  repeats up across the courses, and the stitch is repeated for every wale. That is, an inlay  34  begins, in one embodiment as shown in stitch construction  30 , at each of wales W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , W 8 , W 9 , and each inlay repeats across the courses. Thus, successive inlays  34  partially overlap preceding inlays  34  forming a portion of the grid or mesh structure. Similarly, yarn  53 , guided by guide bar L 3 , forms an opposed inlay  33  by lapping, for example, to the left of C 1 -W 4 , then right to lap C 2 -W 6 , then left to lap C 3 -W 6 , then right to lap C 4 -W 6 , and finally left to C 5 -W 4  to form a cycle of the inlay. As with inlay  34 , inlay  33  repeats across courses with a yarn forming an inlay  33  beginning in every wale. It is appreciated that yarns  53  and  54  form opposed inlays  33  and  34  due to the opposed shogging of guide bars L 3  and L 4  to produce the conformation of the grid or mesh with relatively high width stability. Portions of yarns  53  and  54  running generally closely spaced and in a slightly angled fashion, in one embodiment, form horizontal elements  105 H of the grid or mesh as described here before. The generally vertical elements  105 V of the grid or mesh are formed by the partially overlapping portions that run sinuously up individual wales between the horizontal elements. 
         [0033]    The mesh or grid is bound or stitched together by open pillar stitches  32  formed utilizing yarn  52  running up each wale. Pillar stitches  32  engage and wrap yarns  53  and  54  where they cross to provide the lengthwise stability of screen  100 . In non-patterned area  102  yarns  51 A and  51 B, guided by Jacquard sections L 1 A and L 1 B, respectively, generally align with, and lay adjacent, yarn  52  running along the wales. In one embodiment, yarns  51 A and  51 B from open pillar stitches  31 A and  31 B, respectively, in unison with stitches  32  in non-patterned areas  102 . Because of the changing nature of the stitches formed by yarns  51 A and  51 B, the yarns may be creel fed. 
         [0034]    In patterned areas  104 , yarns  51 A and  51 B are diverted to form open tricot stitches  31 AP and  31 BP crossing one or more wales. For example, yarn  51 A binds other yarns at C 1 -W 2 , then laps leftward to C 2 -W 1  binding and engaging yarns at that location, and finally laps rightward to C 3 -W 2  to form open tricot stitch  31 AP. It is to be noted that the portion of yarn  51 A lapping from, for example, C 2 -W 1  to C 3 -W 2  crosses a portion of the mesh cell formed by vertical grid elements  105 V formed along wales W 1  and W 2  and the horizontal grid elements  105 H between C 1  and C 2  and between C 4  and C 5 . Yarn  51 A crossing a mesh cell creates part of a pattern area  104 . Likewise, yarn  51 B binds other yarns at C 1 -W 3 , angles leftward to bind other yarns at C 2 -W 1 , and finally angles rightward to form open tricot stitch  31 BP. As with yarn  51 A, it is appreciated that yarn  51 A being thus diverted crosses one or more mesh cells and forms part of a pattern area  104  by partially closing an opening in the mesh. It is further appreciated that by selectively diverting yarns  51 A and  51 B at various locations in fabric, various pattern structures may be produced. 
         [0035]    Another embodiment entails the use of the 2 needle/3 needle inlay technique as illustrated in  FIG. 4 . The description of the yarns and construction as regards the yarns  61 A,  61 B, and  62  forming stitches  41 A,  41 AP,  41 B,  41 BP, and  42  is identical to that of  FIG. 3  for yarns  51 A,  51 B, and  52  forming stitches  31 A,  31 AP,  31 B,  31 BP, respectively. Insect screen  100  in this embodiment differs from the embodiment illustrated in  FIG. 3  in regards to inlays  43  and  44  formed by yarns  53  and  54  guided by ground bars L 3  and L 4 , respectively. Inlay  44  spans only two wales, or needle locations while inlay  43  spans three wales, or needle locations. For example, yarn  64  laps rightward around C 1 -W 7 , then leftward around C 2 -W 6 , then rightward around C 3 -W 6 , then leftward around C 4 -W 6 , and finally rightward to C 4 -W 7  to form inlay  44  spanning two wales, or needle locations. Yarn  63  laps leftward around C 1 -W 3 , then rightward around C 2 -W 5 , then leftward around C 3 -W 5 , then rightward around C 4 -W 5 , and finally leftward to C 4 -W 3  to form inlay  43  spanning three wales, or needle positions. As in the case of inlays  33  and  34  in  FIG. 3 , inlays  43  and  44  in  FIG. 4  each commence, in one embodiment, in each wale and run along wales across courses as described. It is appreciated that the 2 needle/3 needle inlay technique provides relatively lower widthwise stability of insect screen  100  as compared to the earlier-described embodiment that employs the 3 needle/3 needle inlay technique, albeit with a lower yarn consumption. Further, 2 needle/3 needle inlay technique may provide stiffer horizontal, or widthwise, elements  105 H in insect screen  100  due to the shorter wale-to-wale yarn traverses included in inlay  33 . Additionally, the 2 needle/3 needle inlay technique provides cleaner, more balanced in width and length mesh or grid openings. 
         [0036]    The embodiment described above utilizing the 2 needle/3 needle inlay technique also provides mesh or grid opening spacing of about 14 openings per inch. Other opening spacings can be produced. For example, employing an  18  gauge single Jacquard machine and using 3 needle/3 needle or 3 needle/4 needle inlay techniques can produce insect screen  100  with an opening spacing of about 20 openings per inch. It is appreciated that a wider inlay technique, such as a 3 needle/4 needle limits machine speed relative to narrower inlays. Another example is employing a Rascheltronic machine with 28 needles per inch, or 28 gauge, with a 2 needle/3 needle inlay technique to produce insect screen  100  with opening spacing of about 30 openings per inch. 
         [0037]    Turning now to the method of forming insect screen  100 , it is appreciated that the screen is knitted and subsequently subjected to one or more finishing operations. To facilitate handling insect screen  100  during finishing operations, opposed side selvages are integrally knitted onto the screen. The side selvages are utilized to attach opposed sides of insect screen  100  to pins or hooks of a conveyor that forms a part of the finishing system. The side selvages stretch insect screen  100  and maintain the screen in tension on the conveyer as the conveyor moves the screen through the finishing process. After finishing, the side selvages are removed from insect screen  100 . 
         [0038]    In one embodiment, finishing operations include stretching and tensioning insect screen and subjecting the screen to a heated environment for a certain period of time. This is accomplished using finishing ovens where the conveyor conveys the tensioned insect screen  100  through the ovens. Such finishing systems are well known to those of ordinary skill in the art. In one embodiment, where polypropylene yarns are utilized to construct insect screen  100 , the oven is set at about 330° F. and the screen is retained in the oven for approximately one minute. The melting point of polypropylene yarns is about 330° F., and the softening point is about 290° F. Heating the yarns that comprise insect screen  100  plasticizes the yarns and heat fuses the stitches. This causes insect screen  100  to be “set”, meaning that after being removed from the conveyor, the screen generally assumes the same area it assumes when stretched in tension on the conveyor. Moreover, plasticizing the yarns and heat fusing the stitches tends to make insect screen  100  more rigid. 
         [0039]    As mentioned above, insect screen  100  is tensioned by the side selvages when connected to pins or hooks of the conveyor that moves through the heated area. It is preferable to construct the side selvages of yarns having a higher melting point than the yarns utilized to form insect screen  100 . This will generally preclude the side selvages from being melted during the finishing operation by heat transmitted from the pins or hooks of the conveyor thereby enabling screen fabric  100  to be held throughout the finishing operation. 
         [0040]    The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.