Patent Abstract:
A detention facility cell door lock housing assembly includes a lock mechanism housing to be mounted on the exterior surface of a cell wall adjacent the cell door opening and lock pocket housing correspondingly mounted on the exterior surface of the cell door. The lock mechanism housing includes a stepped side wall having at least a portion with an exterior facing surface to act as a stop. The lock pocket housing includes an opposingly stepped side wall, such that when the door is close the respective side walls fit together and the stop is engaged to prevent further door travel.

Full Description:
BACKGROUND 
     1. Field 
     The present invention relates generally to detention facility cell door locks, and in particular to detention facility cell door locks with protective housings, and further, to such protective housings that are mounted on the exterior of the cell. 
     2. Description of the Problem and Related Art 
     Many detention facilities have cells that were originally provided with conventional swinging doors locked with a lock mounted in a door frame jamb and that fits within a 2″ wide face. Many of these locks have to be replaced due to inmate access to the lock bolt (tampering), fatigue and destructive physical abuse directly to the door and frame. 
     Conventional frame- and door-mounted cell lock mechanisms are subject to tampering because the thickness of a typical door frame and the relatively thin width of the door stop (typically about ⅝ of an inch) gives an inmate an opportunity to use a playing card, a credit card, a calling card, or something similar that is stiff but flexible, and small enough to be secretly carried, to block the lock bolt by inserting the object in the path of the lock bolt as the cell door is closing. 
     An inexpensive alternative to complete replacement of the door, frame and lock, and a common practice is to replace the lock and lock pocket by cutting away a large portion of the wall and frame and installing a new lock pocket with lock known as “recessed mounting.” This invasive method can compromise the structural integrity of the wall and door and involves extensive preparation for demolition and clean up after installation. The time to modify a door and frame in this manner means detention facility staff must closely coordinate the relocation and heightened supervision of inmates for prolonged periods. 
     Accordingly, a structure is needed that securely supports a lock mechanism for prison or jail cells that deters or inhibits tampering, but may be installed quickly, cheaply, and does not impair the structural integrity of the existing wall and door. 
     SUMMARY 
     For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     A detention facility cell door lock housing assembly includes a lock mechanism housing to be mounted on the exterior surface of a cell wall adjacent the cell door opening and lock pocket housing correspondingly mounted on the exterior surface of the cell door. The lock mechanism housing includes a stepped side wall having at least a portion with an exterior facing surface to act as a stop. The lock pocket housing includes an opposingly stepped side wall, such that when the door is close the respective side walls fit together and the stop is engaged to prevent further door travel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
         FIG. 1  is a perspective view of an exemplary lock housing assembly for mounting on the exterior surfaces of the door and wall (partial views) of a detention facility cell; 
         FIG. 2A  depicts an exemplary lock mechanism housing mounted to the exterior surface of a cell wall and door frame; 
         FIG. 2B  shows an opposing view of the exemplary lock mechanism housing of  FIG. 2B  along with a lock pocket housing mounted to the exterior surface of a cell door; 
         FIG. 3A  is an elevation view of respective exemplary mounting plates for mounting the lock housing assembly; 
         FIG. 3B  is a plan view from above of the lock housing assembly of  FIG. 1 ; 
         FIG. 3C  is a side elevational view of an exemplary lock pocket housing; 
         FIG. 3D  is a side elevational view of an exemplary lock mechanism housing; and 
         FIG. 4  is a section view from above showing the engaging of the lock housing assembly mounted on the exterior surfaces of the cell door and cell walls. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments of the present invention and their advantages are best understood by referring to  FIGS. 1 through 4  of the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. Throughout the drawings, like numerals are used for like and corresponding parts of the various drawings. 
     This invention may be provided in other specific forms and embodiments without departing from the essential characteristics as described herein. The embodiments described above are to be considered in all aspects as illustrative only and not restrictive in any manner. The appended claims rather than the description and drawings indicate the scope of the invention. 
       FIG. 1  depicts an exemplary lock housing assembly  10  enclosed in which is a lock mechanism  7 . The housing assembly  10  is mounted on the exterior surfaces of a cell door  3  and wall  2  across the door jamb  5 .  FIGS. 2A &amp; 2B  show the respective exterior components of the housing assembly  10  comprising a lock mechanism housing  201  that is mounted to the wall  2  adjacent the existing door jamb  5 . The lock mechanism housing  201  supports the lock mechanism  7 , and is configured with a frame lock facing wall  231  stepped-shaped to include a rabbet portion  211  in which is defined openings through which a lock bolt  205  and a lock roller bolt  207  may be selectively extended when the cell door  3  is closed. The frame lock facing wall is further shaped to define a stop  213 , analogous to a conventional door stop that is defined by a soffit in a conventional door frame. The stop  213  is essentially a perpendicular transition between the rabbet portion  211  and a shoulder portion  215  and extends generally parallel to the cell wall exterior surface. The shoulder portion  215  extends between the wall surface and the stop  213 . 
       FIG. 2B  provides a view of a lock pocket housing  203  mounted to the exterior surface of the door  3  and configured with a door strike mounting wall formed to define surfaces opposing those defined by the frame lock facing wall, having one surface that will seat against the stop  213  when the door  3  is closed. The lock pocket housing  203  includes a second shoulder portion  217  in which is defined an opening  204  for receiving the lock bolt  205  and an opening  202  for receiving the lock roller bolt  207 . A strike plate  209  may be installed with corresponding openings to protect the structure of the shoulder portion  217  surrounding the openings  204 ,  202 . The door strike mounting wall  233  is shaped to include a stop mating surface  221  interposed between the shoulder portion  217  and a second rabbet portion  219 . An additional optional feature is a guard flange  225  extending laterally from the front of the lock pocket housing  203 . The lock mechanism housing  201  is preferably configured with a third rabbet  224  dimensioned to receive the guard flange  225  when the door  3  is closed in order to provide a flush face across the front of the assembly  10 . The guard flange  225  inhibits access to the locking bolts from the outside of the cell when the cell door is closed. 
       FIG. 4  is a cross-section view, looking vertically downward, which illustrates the lock mechanism housing  201  mounted on the exterior surface  402  of the existing cell wall  2  and the exterior surface  404  of the existing door frame  5 . The lock pocket housing  203  similarly is mounted on the exterior surface  406  of the existing door  3 . This view also shows the existing door frame  5  defines a door stop  410  against which the door  3  is seated when the door is closed. 
     It can be seen that the two respective housings  201 ,  203  are shaped such that when the door  3  is closed the stop mating surface  221  of lock pocket housing  203  is seated against the stop  213  of the lock mechanism housing  201 . Further, the housings  201 ,  203  are formed so that the shoulder portion  215  and the second rabbet portion  219  extend outward from the door frame  5  and door  3 , respectively, and formed so that the stop  213  extends laterally offset vis-á-vis the door frame  5 , i.e., away from the door frame edge. Moreover, respective opposing surfaces  215 ,  219  and  211 ,  217 , are matingly stepped and dimensioned appropriately to provide a close engagement of the two housing components  201 ,  203 , minimizing the gap between the two opposing surfaces. 
     The depth of the shoulder portion  215  should optimally be as great as possible while still accounting for space constraints to reduce the likelihood of an inmate inserting objects between the lock mechanism bolts  205 ,  207  and their respective openings  204 ,  202  in the lock pocket housing  203 , e.g., a playing card, credit card, or other objects which may be stiff but flexible and prevent the lock bolt from engaging. The width of the stop  213  is also dimensioned to be as wide as possible. Preferably, the width of the stop  213  should be greater than that of the standard door stop  410  which is about ⅝ inch. Still more preferably, the width of the stop  213  is between about ⅞ inch to about one inch, or greater, including widths of about 15/16 inch. As with the extended depth of the shoulder portion  215 , the wider stop  213  surface reduces the ability of an inmate to tamper with the lock function by interposing a stiff but flexible card. 
     Both housing components  201 ,  203  are preferably formed with sloping top and bottom surfaces. This feature provides enhanced protection of the locking mechanism from overhead impacts as well as a clean, modern appearance. 
       FIGS. 3A through 3D  varying aspects of an exemplary lock housing assembly  10  and, in particular illustrate exemplary methods of mounting the assembly  10  to the cell door  3  and cell wall  2  exterior surfaces. The exemplary assembly  10 , therefore, comprises a wall mounting plate  301  and a door mounting plate  303  for mounting of the lock mechanism housing  201  and the lock pocket housing  203  respectively. 
     Various methods are known in the art for securely attaching similar structures to wall and door surfaces, and thus, the following description is merely provided for illustration, and should not be considered to be the sole technique for mounting of the lock housing assembly  10 . Accordingly, in a preferred embodiment, each mounting plate  301 ,  303  comprises a back plate  301   a ,  303   a , in each of which may be defined a plurality of slots  302  that can provide access to the mounting surface for a welding torch, thus welding the mounting plate  301 ,  303  to the mounting surface. Of course, the plates may also be bolted to the wall or door, but this requires drilling holes in each structure which increases installation time. 
     Each mounting plate  301 ,  303  may include a plurality of attachment flanges  305  that extend perpendicularly, in either direction, from the back plate  301   a ,  303   a , and may be configured with fastener openings to allow attachment of the housing  201 ,  203  to the mounting plate  301 ,  303 . Additionally, the housing  201 ,  203 , may include a back wall  311  and may be attached to each mounting plate  301 ,  303  with a plurality of suitable fasteners  309  through openings in each wall  311 . Each housing  201 ,  203  also may include reinforcing ribs  307  and other structures for supporting and mounting of a locking mechanism. 
     An additional feature resides in the design of the lock pocket housing  203  in that it is hollow. Often, an inmate will stuff any kind of debris, such as paper scraps or candy or food wrappers, in the bolt hole in the door frame, which, if it is shallow enough, will fill in a relatively short amount of time and may prevent the lock bolt from fully engaging the bolt hole, compromising the security of the cell. A hollow lock pocket housing  203  deters this tactic as it would require a greater amount of debris and a longer period of time to full sufficiently to interfere with the lock bolt operation. In addition, the housing  203  may optionally be configured with an opening to allow periodic cleaning of the housing interior. 
     It will be appreciated that since the respective housings are surface-mounted to the existing door and frame, the structural integrity of the wall and frame are preserved. Further, installation time, and thus, down time is greatly reduced, which in turn, reduces disruption of the security routine, and temporary relocation of inmates during installation. Applicant has successfully tested prototypes of the above-described structures and installation method in accordance with ASTM F1450-05 standard methods for hollow metal swinging door assemblies for detention and correctional facilities. 
     As described above and shown in the associated drawings, the present invention comprises an apparatus for a detention facility cell door lock housing assembly. While particular embodiments of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications that incorporate those features or those improvements that embody the spirit and scope of the present invention.

Technology Classification (CPC): 4