Abstract:
The present invention relates to a locking mechanism, especially for sliding glass patio doors. The invention provides a locking device with improved strength and increased resistance to forced entry for new and existing sliding glass patio doors. The invention further provides a retrofit device to occupy a void or crevice in the lock mechanism such that force against the lock mechanism is distributed along adjacent parts.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an improved locking mechanism, especially for sliding glass patio doors.  
       BACKGROUND  
       [0002]     Glass patio doors have been used for many years in residential home construction. Glass patio doors are typically plate glass with a metal or plastic border on at least part of one edge of the glass. This border houses a lock mechanism. The lock mechanism engages a striker mounted in a metal or plastic door frame. Glass patio doors typically slide on bearings or rollers within a frame to achieve open and closed positions.  
         [0003]     The structural characteristics of glass demand that locking mechanisms for glass patio doors be constructed differently than locks for wooden doors or steel doors. Doors constructed of wood or steel typically are at least 1½ inches thick. This thickness is sufficient to house the locking mechanism within the door. Sliding glass doors, however, are typically less than ½ inch thick, which is insufficient to house a robust internal locking mechanism of the kind typically found in standard wooden or steel doors. Constructing the sliding glass door to a comparable thickness as that of a typical wooden or metal door is impractical; the weight of the glass would be very difficult to slide even with the aid of bearings or rollers.  
         [0004]     Consequently, locks for sliding glass patio doors are typically mounted in the metal or plastic border on one edge of the plate glass. In the closed and locked position, the lock engages a stationary metal or plastic striker mounted to a door frame surrounding the entire door.  
         [0005]     Conventional sliding glass patio door designs maximize the area of glass used to construct the door to emphasize the aesthetic quality of glass. Unfortunately, this comes at a cost—security. As stated previously, the sliding glass patio door lock is housed in the marginal metal or plastic border of the plate glass. This border is constructed to preserve the maximum surface area of the glass and is not much thicker than the thickness of the plate glass.  
         [0006]     Furthermore, the conventional design of glass patio doors allows for voids and crevices in critical areas around the lock mechanism. Consequently, the border does not allow for a robust locking mechanism such as that found in a hinged metal or wooden door. The conventional design permits the flexing, stressing, and eventual breakage of the lock mechanism. This weakness, at least in part, results in the targeting of sliding glass patio doors as access points for home invasions.  
         [0007]     In addition, sliding glass patio doors are now required to pass more stringent testing for forced entry. Such increased security standards underscore the deficiencies in conventional sliding glass patio door lock design.  
         [0008]     Thus, there is a need for an improved sliding glass patio door lock.  
         [0009]     Furthermore, there is a need for an economical, easily installed retrofit device that increases the strength of the door lock mechanism and enhances security against forced entry for sliding glass patio doors already in use.  
       SUMMARY OF THE INVENTION  
       [0010]     It is an object of the present invention to provide a locking device with improved strength and increased resistance to forced entry for new sliding glass doors.  
         [0011]     It is a further object of the present invention to provide an economical, easily installed retrofit device for a sliding glass door lock mechanism.  
         [0012]     It is a further object of the present invention to provide a retrofit device to occupy a void or crevice in the lock mechanism such that force against the lock mechanism is distributed along parts adjacent to the lock mechanism. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of a sliding glass patio door with an arrow pointing to the lock mechanism housing.  
         [0014]      FIG. 2  is an exploded view of the conventional sliding glass door lock mechanism.  
         [0015]      FIGS. 3   a  and  3   b  are sectional views of the current sliding glass door lock mechanism in the unlatched ( FIG. 3   a ) and latched ( FIG. 3   b ) positions.  
         [0016]      FIGS. 4   a  and  4   b  are sectional views of the improved sliding glass door lock mechanism in the unlatched ( FIG. 4   a ) and latched ( FIG. 4   b ) positions.  
         [0017]      FIG. 5  is a side view of a unitary hook reinforcing element for a sliding glass patio door, including the lock hook, reinforcing boot, mounting hole, and mounting ear. 
     
    
     DETAILED DESCRIPTION  
       [0018]     In one aspect, the invention is a sliding glass door assembly having an improved locking mechanism. The improved locking mechanism of the present invention provides increased resistance to forced entry.  
         [0019]     Embodiments of the present invention are depicted in  FIGS. 1-5 . It will be understood that the illustrations are for describing the typical embodiment of the invention and are not intended to limit the invention. Like numbers refer to like elements throughout the drawings and specification.  
         [0020]      FIG. 1  depicts a sliding glass door assembly  10 . The sliding glass door assembly  10  typically includes a sliding door  11  having a border  12  and a lock hook mechanism housing  13 . The sliding door  11  slides between closed and open (arrow) positions within a U-shaped channel  14  (i.e., guide). The channel  14  may be part of the door frame  19 , or may be a separate piece connected to the frame  19  with one or more fasteners  18  (e.g., a sheet metal screw). Other appropriate fasteners are known to those of ordinary skill in the art.  
         [0021]     Referring to  FIG. 2 , a conventional sliding glass door lock mechanism is depicted. In a typical embodiment, the sliding door  11  includes a lock hook mechanism housing  13  within the sliding door border  12 . The lock hook mechanism housing  13  includes a front plate  15  and a back plate  16 , and may also include a handle  17 . The handle  17  may be mounted to the lock hook mechanism housing  13  using one or more fasteners  18 , such as a threaded screw.  
         [0022]     Other appropriate fasteners are known to those of ordinary skill in the art. One-way screws and other tamper-resistant fasteners, such as those manufactured by Bryce Manufacturing, Inc., (Gilbert, Ariz., USA) are useful to resist forced entry. The unique head pattern of tamper-resistant fasteners serves to deter a person using standard tools from gaining entry through the sliding door  11  by disassembling the lock hook mechanism housing  13 .  
         [0023]     The handle  17  may be made of metal, wood, plastic, any combination thereof, or any suitable material known to those of ordinary skill in the art. In addition, the handle  17  may be coated with a soft, resilient material, such as foam rubber or the like. Coating the handle  17  serves at least three purposes. First, the handle  17  is safer in the event a person strikes the handle  17 . Second, the handle  17  is softer to the touch and less prone to temperature extremes in hot or cold weather. Third, the handle  17  is more aesthetically pleasing. Alternatively, the handle  17  may be integrated with the lock hook mechanism housing  13 .  
         [0024]     The front plate  15  further includes a lock hook  20 . The lock hook  20  may be moved upward or downward using a lock hook controller  21 . Movement of the lock hook  20  engages or disengages the lock hook  20  with the striker  22 . In a typical embodiment, the striker  22  is mounted to the sliding glass door frame  19  using one or more fasteners  18 , such as a threaded screw.  
         [0025]      FIGS. 3   a  and  3   b  depict sectional views of the conventional lock hook mechanism housing  13  in the unlatched and latched positions, respectively. Shown in  FIG. 3   a,  the lock hook mechanism housing  13  moves with the sliding door border  12  in the direction of the arrow toward the striker  22 . Depicted in  FIG. 3   b,  when the lock hook mechanism housing  13  reaches the striker  22 , the lock hook  20  engages the striker  22  to close and lock the door (not shown).  
         [0026]     Shown in  FIGS. 3   a  and  3   b,  the lock hook  20  is mounted within the lock hook mechanism housing  13  using conventional and tamper-resistant mounting hardware, such as a bolt  23  and a nut  24 . Other suitable mounting hardware is known to those of ordinary skill in the art. Furthermore, the lock hook mechanism housing  13  includes a mounting flange  25  to accommodate the lock hook  20 . The conventional design generally shown and described in  FIGS. 3   a  and  3   b  leaves a lock hook mechanism housing void  26  between the lock hook mechanism housing  13  and the front plate  15 .  
         [0027]      FIGS. 4   a  and  4   b  depict the improved sliding glass door lock mechanism of the present invention. In a typical embodiment, the lock hook  20  includes a reinforcing boot  30 . The reinforcing boot  30  substantially fills the void  26  between the lock hook mechanism housing  13  and the front plate  15 . Accordingly, the strength of the sliding glass door lock mechanism is improved in the closed and locked position.  
         [0028]     In another aspect, the invention is a unitary hook reinforcing element  27  suitable as a retrofit device for existing patio door locks. Depicted in  FIG. 5 , the lock hook  20  and reinforcing boot  30  are a single piece of material constructed to fit existing lock hook mechanism housings  13 . The unitary construction may include a mounting ear  31  to brace the mounting of the lock hook  20  and the reinforcing boot  30  within the mounting flange  25  of the lock hook mechanism housing  13 . The unitary hook reinforcing element  27  may further include a mounting aperture  32  to accommodate standard mounting hardware, such as a bolt  23 , nut  24 , or other fastener known to those of ordinary skill in the art.  
         [0029]     Thus, the unitary hook reinforcing element  27  of the present invention is suitable as a retrofit device for existing patio door locks. The unitary hook reinforcing element  27  of the present invention improves upon existing patio door locks by occupying a void  26  (see  FIG. 3 ) in the lock hook mechanism housing  13 . Thus, the strength of the sliding glass door assembly  10  is improved.  
         [0030]     The lock hook  20  and reinforcing boot  30  may be made of plastic or metal material suitable for use in a sliding door border  12 .  
         [0031]     Plastic materials include, but are not limited to, fiberglass, fiberglass-reinforced nylon, glass-filled nylon, glass-filled polypropylene, polyester, and vinyl.  
         [0032]     Metal materials include, but are not limited to, steel, titanium, brass, pewter, aluminum, or tin, or any alloys thereof. Furthermore, the metal material may be plated or coated to reduce its friction coefficient or to retard oxidation and corrosion. Substances suitable for this purpose include, but are not limited to, zinc, brass, bronze, or chrome.  
         [0033]     The lock hook mechanism housing  13  of the present invention is designed to pass a Forced Entry Resistance Test for locking mechanisms. Briefly, the Forced Entry Resistance Test includes a five-minute disassembly sequence, a five-minute tool manipulation sequence, and a series of “pulls” to test the locking mechanism strength.  
         [0034]     During the disassembly sequence, an operator attempts to access the lock mechanism by removing any protective covering (e.g., snap beads, weep hole covers, and Phillips or flat screws) from the exterior side of the sample within the allotted five-minute period.  
         [0035]     During the hand and tool manipulation test, the operator has five minutes to manipulate the locking mechanism by hand and with basic tools (e.g., a wire and a putty knife).  
         [0036]     Finally, the strength of the locking mechanism is tested using a series of “pulls.” Pulls exert force against the locking mechanism. The amount of force depends upon the rating (i.e., grade level) desired for a given locking mechanism. For example, the rating for a locking mechanism within a standard steel door would probably differ from the rating for a sliding glass door assembly of the present invention. The resisting force of the locking mechanism is measured with a dynamometer.  
         [0037]     In the specification and the drawings, typical embodiments of the invention have been disclosed. Specific terms have been used only in a generic and descriptive sense, and not for purposes of limitation. The scope of the invention is set forth in the following claims.