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CROSS-REFERENCE TO RELATED DOCUMENTS 
       [0001]    The present application claims priority to Provisional Patent Application 62/185,483 filed on Jun. 26, 2015, and all disclosure of the parent application is incorporated at least by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is in the field of entrance and egress hardware including gate latches and pertains particularly to a system for latching and unlatching a gate. 
         [0004]    2. Discussion of the State of the Art 
         [0005]    In the art of construction, particularly of perimeter fencing, gate latches are used to affect latching between a swing gate and a gatepost. The most common latches are vertical latches that, with the aid of gravity and a passive bar-grabbing design function to latch gates to prevent entrance to or egress from a fenced area. 
         [0006]    Many vertical latch assemblies include a flat mounting plate and latch housing with a pivotally mounted latching plate disposed within the latch housing. Gravity keeps the latch plate in the closed position. A rounded front face on the latch plate allows a latch bar to be inserted into the latching position of the assembly, such action lifting the latch plate enough to accept the bar. Gravity then urges the latch plate down over the latch bar providing a latched gate. A limitation with current vertical latches is that there are no user-operated components for opening or for closing the latch. A user may swing the gate closed to effect latching but must manually lift the latch to release the gate. 
         [0007]    The inventor is aware of a tube assembly that houses a pull line inserted through the tube that may be tied or otherwise connected to a seat on a vertical latch plate of a mounted latch bar assembly and to a handle or knob on the pull end of the gate post. The tube assembly contains a spring installed over and crimped in place on the pull line to provide resistance on pull or lift up of the latch plate and mild back pressure when released or relaxed to provide some force, however slight, to assist the latch plate to stay closed over the latch bar. One limitation of the tube assembly is that there are no user-operable and aesthetic interfaces on the side of the assembly opposite the pull knob. 
         [0008]    Therefore, what is clearly needed is a gate latching and unlatching system that addresses the limitations discussed above. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In one embodiment of the present invention a gate latch system is provided, comprising a latch line operating sub-assembly comprising an elongated tube of a first length greater than a thickness of a gatepost and a tube diameter, the elongated tube having external male threads the full first length and extending through a hole with a bore diameter greater than the tube diameter through the gatepost, a first tubular cap element having a cap length with a female thread from a flanged open end, the flange diameter greater than the hole bore diameter, the female thread matching the thread of the elongated tube, and a substantially closed opposite end having a central hole of a diameter to freely accommodate a latch line, the first cap element threaded onto the elongated tube with the flange bearing on a first side of the gatepost, a second tubular cap identical to the first tubular cap element, the second cap element threaded onto the elongated tube with the flange bearing on a second side of the gate post opposite the first side, such that the cap elements securely contain the elongated tube through the gatepost, a latch line having a first end and a second end, passing through the central hole in the first cap element, the elongated tube and the second cap element, a coil spring having a spring length surrounding the latch line within the elongated tube with a first end bearing on the closed end of the first cap element and a second end bearing on a crimp element crimped to the latch line, and a pull knob affixed to the first end of the latch line such that the pull knob bears on the closed end of the first cap element with the coil spring extended. The system in one embodiment has a gravity latch mechanism comprising a body presenting a mounting flange to the second side of the gatepost, the mounting flange having two side-by-side vertically oriented slots allowing the body to be adjustably mounted to the second side of the gatepost at a point on a vertical centerline below the mounting of the latch line operating sub-assembly, and angled entrance for receiving a latch bar, and a slot for restraining a latch plate, a gravity-operated latch plate mounted at a pivot point in the body, with a groove for receiving and latching the latch bar by rotating around the pivot point, the latch plate having an operating arm extending about two inches upward from the pivot point at an outward angle from the gatepost, the operating arm having a planar portion facing the gatepost with a vertically-oriented slot receiving the second end of the latch line, terminated by a crimp element wider than the slot crimped to the second end, and ending in a separate planar portion oriented for a operating the latch plate manually, such that withdrawing the latch line against the coil spring lifts the latch plate. The system further has a latch bar comprising a horizontally-oriented mounting base having side-by-side horizontal slots adjustably mounting the latch bar by screw fasteners to a gate adjacent the gatepost at a height to engage the latch bar with the gravity latch mechanism, a bar extension extending first outward and then parallel to the gate an extent to engage the latch plate in the gravity latch mechanism with the gate in a closed position, and a handle knob joined to the latch bar by one of the fasteners. Pulling on the pull knob at the first end of the latch line on one side of the gate lifts the gravity latch on the other side of the gate, allowing the gate to swing open, and the spring in the latch line sub-assembly extends the latch line when the pull knob is released, allowing the gravity latch mechanism to reposition to latch the latch bar when the gate closes again. 
         [0010]    In one embodiment the pull knob comprises a tubular first portion having an externally threaded open first end and a closed second end having a central opening receiving the latch line retained by a crimp element, and an internally threaded cap closure engaging the tubular first portion. Also in one embodiment the pull knob comprises one or more lighting elements illuminating the knob. Also in one embodiment the one or more lighting elements comprise light-emitting diodes and a power supply mechanism. Also in one embodiment the power supply mechanism incorporates a solar panel. 
         [0011]    In one embodiment the handle knob joined to the latch bar comprises a tubular first portion having an externally threaded open first end and a closed second end having a central opening receiving one of the screw fasteners, and an internally threaded cap closure engaging the tubular first portion. Also in one embodiment the handle knob comprises one or more lighting elements illuminating the knob. Also in one embodiment the one or more lighting elements comprise light-emitting diodes and a power supply mechanism. Still in one embodiment the power supply mechanism incorporates a solar panel. 
         [0012]    In one embodiment the system further comprises lighting elements joined to one or both of the gatepost or the gate. Also in one embodiment the lighting elements are LEDs powered by one or more solar panels. Also in one embodiment the system further comprises lighting elements in one or more parts of the system or on the gatepost or gate, one or more power supplies providing power to the lighting elements, and one or more manual or automatic switching elements for switching power on and off to individual ones of the lighting elements. And in one embodiment the tubular cap elements exhibit longitudinal ridges providing grip enhancement for a user to assemble the tube and caps through a gatepost. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]      FIG. 1  is a partially sectioned and exploded side elevation view of a gate latching and unlatching system according to an embodiment of the present invention. 
           [0014]      FIG. 2  is a front elevation view of the system of  FIG. 1  with the lighting components removed for clarity. 
           [0015]      FIG. 3  is a perspective view of the threaded cap of  FIG. 1  depicting a ridged outer surface. 
           [0016]      FIG. 4  is a perspective view of a crimp nut of  FIG. 1  depicting inside threads for crimping onto the latch line. 
           [0017]      FIG. 5  is a side elevation view of system  100  assembled and latched. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    In various embodiments described in enabling detail below the inventor provides a unique system for latching and unlatching a swing gate. The present invention is described using the following examples, which may describe more than one relevant embodiment falling within the scope of the invention. 
         [0019]      FIG. 1  is a partially-sectioned and exploded side-elevation view of a gate latching and unlatching system  100  according to an embodiment of the present invention. System  100  may be installed on and through a gatepost and adjacent vertical gate member such as a gatepost  101  shown partially sectioned, and a vertical gate member illustrated herein as a vertical gate member  102 . Gatepost  101  may be made of a variety of materials such as wood, Polyvinyl Chloride (PVC) or some other weather and sun (UV) resistant material, or metal or a combination of materials. Gatepost  101  may be solid such as a solid wooden post or a hollow post without departing from the spirit and scope of the present invention. Vertical gate member  102  may be manufactured of wood, PVC or some other weather and sun (UV) resistant material, metal, or a combination of materials. 
         [0020]    System  100  includes an elongate threaded tube  103 . Tube  103  may be manufactured of Polyvinyl Chloride (PVC) or some other weather and sun (UV) resistant material or metal without departing from the spirit and scope of the invention. Tube  103  has male threading along the full length thereof in one implementation. Tube  103  is adapted to be inserted through an opening formed through gatepost  101 , such as by drilling, and has an outside diameter just smaller than the diameter of the opening formed through gatepost  101 . Tube  103  must have a length that is longer than the thickness of gatepost  101  so that it may be secured in position through the post. Tube  103  is therefore preferably provided in a length that would accommodate being cut to length required to facilitate a secure mounting through any host gatepost that is of lesser thickness than the length of tube  103 . Tube  103  may therefore be cut to a proper length for gateposts of different thicknesses. 
         [0021]    System  100  includes two threaded caps  106  configured to be threaded onto tube  103 , one at each end, once tube  103  is cut to proper length and internal elements are assembled. Threaded caps  106  may be molded from PVC or some other weather and sun (UV) resistant material. Caps  106  each comprise a tubular body closed at one end with a central opening through the closed end at proximate center in one implementation. The opening is just large enough to pass a latch line  105 . Cap  106  is female threaded on the inside diameter of the body portion at least partly the length of the cap to the closed end. The open end of the cap body includes a flanged rim having an outside diameter larger than the outside diameter of the cap body, and greater in diameter than the diameter of the bore through the gatepost to accommodate tube  103 . 
         [0022]    Caps  106  thread onto the tube ends with the flanges at the open ends bearing on the gate post, locking the tube into its inserted position through the post. Tube  103  has an inside diameter  104  large enough to accept latch line  105  inserted there through. Latch line  105  may be manufactured of a resilient and flexible material such as PVC or some other weather and sun (UV) resistant material, a coated wire, or a strong fiber line or cord. 
         [0023]    Latch line  105  has an outside diameter that is smaller than the inside diameter  104  of tube  103 . The inside diameter of tube  103  may be small enough to prevent latch line  105  from doubling or kinking within the tube. In one embodiment a latch spring  126  is assembled over the latch line within tube  103  to provide spring resistance to a pull knob assembly  107 , described in detail below, against cap  106  in operation. The inside diameter of latch spring  126  is larger than the outside diameter of latch line  105 , and the outside diameter of latch spring  126  is smaller than the inside diameter  104  of tube  103 , but larger than the diameter of the central opening through the closed ends of caps  106 . One end of spring  126  may therefore bear against the inside of the closed end of cap  106 . Latch spring  126  may be a straight spring or a tapered spring without departing from the spirit and scope of the present invention. 
         [0024]    Latch line  105  passes through the central openings on the otherwise closed ends of threaded caps  106  at both ends of tube  103  in assembly. Latch spring  126  bears on the inside end of cap  106 . At the opposite end of spring  126  a crimp nut  111  is placed over line  105  and crimped closed. In one embodiment a plastic washer  109  resides between crimp nut  111  and the end of spring  126 . 
         [0025]    Latch line  105  extends further out of threaded cap  106  through an optional rubber or plastic spacer  108  and through the central opening in an otherwise closed end of a pull-handle body  110 , which is part of pull knob assembly  107 . Pull handle body  110  is closed at one end and open at the opposite end to allow assembly of latch line  105 . Handle body  110  may be manufactured of PVC or some other weather (UV) resistant material. A crimp nut  111  is placed on the end of latch line  105  within body  110 , and crimped. 
         [0026]    In one implementation handle body  110  has male threads on the outside diameter thereof to accept the female threading on a handle cap  112  of pull knob assembly  107 . In another implementation handle cap  112  may be snapped onto handle body  110 . Handle cap  112  may be connected onto handle body  110  to form a convenient user interface for pulling on latch line  105  against the tension of latch-spring  126 . 
         [0027]    Cap  112  has a larger outside diameter than handle body  110  which, in turn, has a significantly larger outside diameter than threaded cap  106 . Cap  112  provides a highly visible user interface for pulling the latch plate to release the latch bar and swing open the gate. Additionally it serves to hide the connection with latch line  105  within handle body  110 . 
         [0028]    It will be apparent from  FIG. 1 , that with tube  103 , line  105 , spring  126  and pull handle  107  all assembled, handle  107  will bear against cap  106  with some minimum force from spring  126 , and a user may pull on pull handle  107  a distance allowed by the length of spring  126 , which also will withdraw the opposite end of latch line  105  the same distance, and when the user releases handle  107 , the handle will return to cap  106  and the latch line will extend again to it&#39;s relaxed position. 
         [0029]    An object of the invention is to operate a gravity latch assembly  139  on one side of gatepost  101  by pulling on handle  107  on the other side of the gatepost. Gravity latch assembly  109  comprises a gravity latch housing  115  within which a vertically-oriented gravity-operated latch plate may operate. Similar gravity latches are known in the art, but the gravity latch according to embodiments of the present invention has features previously unknown in the art. Many of the unique features are a part of latch plate  114 . 
         [0030]    Latch plate  114  may be manufactured of steel or another durable sheet metal suitable for the purpose. Latch plate  114  is generally a flat and relatively thin plate or blade. Latch plate  114  includes a top or neck portion  124  different than known in previous art. One unique feature is that the latch plate has an extended neck portion  124  that extends from assembly  139  at approximately a 45 degree angle from vertical when the gravity latch is closed in latch position. Neck portion  124  is shown partially sectioned in  FIG. 1 , and may be formed from the same sheet metal as plate  114  by heating and twisting the stock to present orthogonally (flat sides) from the broad flat face of the latch plate. Latch plate  114  may have a uniform thickness. 
         [0031]    Neck portion  124  of latch plate  114  hosts a through opening  118  in the form of a slot or round hole. The width of slot  118  is greater than the outside diameter of latch line  105 . Latch line  105  is inserted through opening  118  during installation and a crimp nut  111  is crimped onto the end of latch line  105  such that withdrawing line  105  by pulling handle  107  will lift gravity latch plate  114 . Crimp nut  111  is not seen in  FIG. 1  as it is covered by a plastic cap  113 . Extending line  105  again will allow latch plate  114  to return to its rest or latched position. Neck portion  124  has a right-angle bend the ends at “thumb” extension  119 . Thumb extension  119  provides a simple user interface point that enables or facilitates lifting of the latch plate  114  from the inside of the gate without pulling on knob  107 . Thumb extension  119  may be wider than the rest of neck portion  124 . Thumb extension  119  may be annular and the remaining neck portion rectangular in one implementation. Other shapes may also be used such as a rounded square profile. 
         [0032]    Latch plate  114  is rotatably pinned within a latch plate housing  115  via a latch pin  116 . Latch plate  114  includes a latch bar straight slot having a width just larger than diameter of a latch bar  117 , and a depth such that the latch plate may rotate to close over the latch bar in a position relative to pin  116  that pressure on gate  102  will not cause the gravity latch to open. Latch plate  114  includes a through opening  125  which may be used for a pin to lock the latch plate. The latch plate housing may be manufactured of steel or another durable, weather resistant sheet metal. Latch plate housing  115  may be a section of sheet metal bent over on itself with some space between walls to form the housing with a significant portion cut away to provide relief for a latch bar  117  mounted to vertical gate member  102 . 
         [0033]    The latch plate housing may be formed to provide flat wings  120  to interface with the inside surface of gatepost  101 . Each mounting surface of wings  120  includes an elongate opening such as a slot  121 , better seen in  FIG. 2 . Openings  121  enable adjustable mounting of the latch plate housing to the surface of gatepost  101 . The length of each slot  121  is sufficiently larger in dimension than the mounting hardware (screws) facilitating manual adjustment up or down, and some angular adjustment of the latch housing for proper fit to accept a gate-mounted latch bar such as latch bar  117 . Tube  103  and latch-plate housing  115  are mounted along a common vertical center line, which may or may not be the center line of the gatepost. 
         [0034]    Latch bar  117  in one embodiment comprises a shaft portion of a diameter to be captured by the slot of the latch plate, and a rounded end larger in diameter than the shaft. Latch bar  117  may be manufactured of steel or of another durable metal or durable material that may be weather resistant. Latch bar  117  may be manufactured from a steel rod that is machine workable to alter thickness such as for machining the mounting surface and producing the offset bends required to properly mount and extend laterally from the mounted position on vertical gate member  102 . 
         [0035]    Latch bar  117  is mounted on vertical gate member  102  via a mounting surface (machined flat) on the latch bar on one side. In one implementation a separate mounting plate may be provided to accommodate the mounting of the latch bar on the gate member. Mounting surface  120  of the latch bar includes two slots  122  enabling mounting of the latch bar to the surface of the gate member via screw fasteners. The slots allow for adjustment of the bar in installation to position properly with gravity latch assembly  139 . 
         [0036]    In one embodiment, a knob-style gate-latch handle  123  is provided to cover the mounting point of the latch bar and provide a user hand interface for opening the gate on the side of the latch plate. To this end the thumb extension provides a convenient user interface for lifting latch plate  114  from that side of the gate. 
         [0037]    In operation a user may pull on handle assembly  107  to accomplish upward movement of latch plate  114  against gravity and spring tension to release latch bar  117  allowing the gate to open. The gate may be pushed closed from the other side to recapture latch bar  117  in latch plate  114 . 
         [0038]    In one implementation system  100  may include battery-powered or solar-powered light emitting diodes (LEDs) integrated with certain components of the system for user convenience. In one variation of this implementation, a solar panel  127  is provided atop gatepost  101 . A rechargeable battery  129  may be provided underneath the panel within the gatepost cap. A power line  128  leads to one or more strategically placed LEDs  130 . LEDs  130  are distributed about the top of gatepost  101  beneath the post cap. LEDs  130  may be switched on manually (switch not illustrated). In one implementation a timer (not illustrated) may be provided to switch on LEDs  130  when appropriate such as shortly after the sun sets. 
         [0039]    In another variation of the lighting implementation, a solar collector ring  131  is provided to fit over pull-handle body  110 . A power line  134  connects the collector ring to a rechargeable battery  133  within the hollow space of the handle body. Battery  133  may be mounted or contained in a compartment within the handle body. Power line  134  leads to an LED  132  installed on the user interface surface of handle knob or cap  112 . In one implementation both LEDs  130  and  132  are incorporated in combination to provide solar powered lighting for the top down area of the gatepost and for the pull handle cap. The periods of lighting may be controlled by timer. 
         [0040]    In still another variation of the lighting implementation, a solar collector  135  is provided atop gate member  102 . A power line connects solar collector  135  to a battery  137  contained within latch-gate handle  123 . Battery  137  is connected by power line  138  to an LED  136  installed on the interfacing surface of the latch-gate handle. In one implementation lighting is available at the gate handle, under the gatepost cap, and at the latch line pull handle. 
         [0041]    In one implementation all of the mentioned lighting positions are integrated via switching elements (not illustrated) where a trigger-event switch such as a switch provided to the latch plate and latch pin assembly may power on the LEDs. In such an implementation, a user may activate powering on of the LEDs by moving the latch plate thus triggering the switch to power on the lights. The lighting may assist the user while navigating through the gate in an otherwise dark or unlighted area. Lighting may also be regulated by a timer as described previously. In one implementation components of system  100  such as handle bodies, caps and knobs may be provided with solar activated coatings or manufactured with glow-in-the-dark materials. 
         [0042]      FIG. 2  is a front elevation view of the system of  FIG. 1  with the lighting components not shown for clarity. System  100  is rotated in this view to illustrate a front elevation view of gatepost  101  and gate member  102 . Latch housing  115  is illustrated joined to gatepost  101 . Most of the elements labeled in  FIG. 1  are repeated in  FIG. 2 , to show from a different perspective the association and interactivity of the various elements. 
         [0043]    In an implementation using solar powered, AC powered, or battery-powered illumination, light may be provided at the top area of the gatepost extending down to the latch housing and an additional LED on gate handle  123  may illuminate the immediate area about the handle. Latch pin  116  may comprise a small switch activated by movement of the latch plate. The switch may be optical in nature or a physical switch that is activated by contact with a portion of the latch plate. 
         [0044]      FIG. 3  is a perspective view of threaded cap  106  depicting a ridged outer surface. In one implementation, threaded caps  106  have longitudinal ridges  301  molded in the cap body outer surface for the purpose of improving the ability of a user to grasp and turn the caps such as when threading them onto the tube during installation. Cap  106  is shown in  FIG. 3  as having a flat end surface, but may be rounded or of other shapes as well. 
         [0045]      FIG. 4  is a perspective view of crimp nut  111  depicting inside threads  401  provided for the purpose of ensuring a secure attachment to latch line  105  when the crimp nut is applied and crimped. 
         [0046]      FIG. 5  is a side elevation view of system  100  assembled with the gate closed and latched. Lighting element  130  (LEDs) may light up both sides of the installation. In one implementation light  130  is also provided on the side of the gatepost facing toward the gate. Solar collectors for the LEDs may be provided as described earlier. Again, as with  FIG. 2 , most of the elements shown in  FIG. 1  are again shown to provide a better understanding of placement and interactivity. 
         [0047]    In this view an extra crimp nut  111  is provided as a line stop that abuts against the neck portion of latch plate  114  when the latch spring is relaxed. Lighting in the form of LEDs may be provided to pull handle assembly  107  as LED  132  and on gate handle  123  as LED  136 . Associated solar collectors may be installed to post and or gate components such as collector  131 , collector  135 , and collector  127 . Batteries may be placed and wired as needed. 
         [0048]      FIG. 6  is a side elevation view of gravity latch assembly  139  illustrating an important feature of gravity latch plate  114 . 
         [0049]    It will be apparent to one with skill in the art that the swing gate latching and unlatching system of the invention may be provided using some or all of the mentioned features and components without departing from the spirit and scope of the present invention. It will also be apparent to the skilled artisan that the embodiments described above are specific examples of a single broader invention that may have greater scope than any of the singular descriptions taught. There may be many alterations made in the descriptions without departing from the spirit and scope of the present invention. 
         [0050]    It will be apparent to the skilled person that the arrangement of elements and functionality for the invention is described in different embodiments in which each is exemplary of an implementation of the invention. These exemplary descriptions do not preclude other implementations and use cases not described in detail. The elements and functions may vary, as there are a variety of ways the hardware may be implemented and in which the software may be provided within the scope of the invention. The invention is limited only by the breadth of the claims below.

Summary:
A gate latch system has a latch line operating sub-assembly, a gravity latch mechanism, and a latch bar. The latch line operating sub-assembly has a tube of a first length having male threading along the entire length, allowing the tube to be trimmed to length for gateposts of different widths. The system comprises lighting elements in handles and knobs to aid a user in operation.