An improved latch incorporating adjustable backset and cylinder latch bolt assemblies, working in cooperation with a door handle, mounting rods and spindle. The backset latch includes novel configured inner and outer casing parts through which extend the mounting rods and spindle, and which sandwich therebetween an actuating plate and follower plate arrangement. The cylinder latch bolt further includes a novel subassembly including a bolt mounted in spring biasing fashion via a stem portion extending therefrom and interengaging the actuating plate to selectively retract the bolt into a cylinder shaped and interiorly open body.

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to tubular lock mechanisms and, more specifically, to such lock mechanisms as which incorporates an adjustable backset. More particularly, the present invention discloses an improved backset assembly incorporating modified inner and outer casing parts, as well as a novel “T” shaped hook portion associated with a sandwichingly disposed actuating plate, for the purpose of providing improved backset adjustment. 
         [0003]    2. Description of the Prior Art 
         [0004]    The prior art is well documented with examples of tubular lock assemblies with some form of adjustable backset structure. In particular, a desirable feature of such assemblies is the ability to conform to both longer and shorter backsets. 
         [0005]    A first example of a tubular lock with backset adjustability is set forth in U.S. Pat. No. 6,293,597, issued to Huang, and which teaches a latch bolt cylinder engaged with a casing consisting of two casing parts. An actuating plate is mounted between the casing parts and includes two separate teeth and protrusions. A follower plate, including two separate teeth, is in close contact with the actuating plate and to which the protrusions bear against. A spindle of the tubular lock bears against two teeth of the follower plate, thereby allowing the actuating plate to retract the latch bolt indirectly. Alternatively, the actuating plate can be directly actuated to retract the latch bolt. 
         [0006]    Another example of the prior art is set forth in U.S. Pat. No. 6,257,630, issued to Huang, and which teaches a tubular lock including a latch bolt cylinder that may be extended beyond the doorplate or retracted there into. A casing consists of two casing parts and is engaged to an inner end of the latch bolt cylinder. An actuating plate is mounted between the casing parts and includes two teeth and a number of protrusions. A follower plate is removably held by the protrusions and also has two teeth. A spindle of the tubular lock bears against the teeth of the follower plate or the actuating plate, thereby allowing the actuating plate to retract the latch bolt directly or indirectly. A movable plate is mounted between the casing parts and may be extended beyond the casing parts. The movable plate includes a positioning hole through which one of two mounting posts of the tubular lock extends. 
         [0007]    Finally, another version of a latch bolt mechanism is disclosed in U.S. Pat. No. 6,334,635, again issued to Huang, and which differs from Huang '630 in that it teaches the teeth associated with the actuating plate as including a block formed thereon, the blocks being pressed against by a follower plate that also includes two teeth. When either tooth of the actuating plate or follower plate is pressed against by a spindle of the lockset, the latch bolt is retracted. An extension casing is mounted around the plates and movable toward or away from the latch bolt housing. The extension casing includes a first hole and a second hole through which the spindle of the lockset is selectively extended. 
       SUMMARY OF THE PRESENT INVENTION 
       [0008]    The present invention discloses a latch design with adjustable backset and latch bolt features and which provides structural improvements over prior art latch designs. In particular, the present latch design provides an improved configuration associated with the inner and outer casing portions, as well as the intermediately disposed actuating portion, and such as to provide for improved backset adjustment and operation. 
         [0009]    A handle is rotatably mounted to a housing, with a spindle extending from the handle in rotatably slaved fashion and a pair of fixed mounting rods extending from the housing in parallel fashion relative to the spindle. The backset subassembly is arranged in substantially perpendicular extending fashion relative to the spindle and mounting rods, the backset operatively engaging the handle and, in turn, actuating a latch bolt assembly to linearly withdraw in a direction towards the backset upon rotation of the handle. 
         [0010]    Features of the backset include an inner casing part, an outer spaced apart and aligning casing part, and a linearly actuating plate and a follower plate sandwichingly engaged between the inner and outer casing parts. Each of the inner and outer casing parts having a specified shape and size and each includes a centrally located and aligning opening through which extends the spindle and in combination with at least first and second pairs of individual positioning holes arranged on opposite sides of the central aligning openings and for receiving the mounting rods therethrough. In a preferred arrangement, a third and outermost pair of aligning holes supplements the first side located pair of holes. 
         [0011]    The actuating plate further includes a lengthwise extending and open interior for facilitating passage therethrough by the spindle and mounting rods. The actuating plate further includes an extending end exhibiting oppositely extending hook portions for engaging the latch bolt assembly. The follower plate seats between the casing parts and against the actuating plate to facilitate extension and retraction of the latch bolt assembly, the follower plate being linearly repositioned between shorter and longer backset positions relative to the casing parts. 
         [0012]    The latch bolt assembly further includes a cylinder shaped and interiorly open body within which is mounted a bolt in spring biasing fashion, a stem portion extending from the bolt including gripping tabs for seating the hook portions of the actuating plate and for thereby translating said linear retraction of the actuator plate to the bolt. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Reference will now be made to the attached drawings, when read in combination with the following detailed description, wherein like reference numerals refer to like parts throughout the several views, and in which: 
           [0014]      FIG. 1  is an exploded view of a latch assembly with adjustable backset according to the present inventions; 
           [0015]      FIG. 1A  is a rotated exploded perspective of the latch assembly shown in  FIG. 1 ; 
           [0016]      FIG. 2  is a sectional exploded view of the latch bolt cylinder housing incorporated into the latch assembly; 
           [0017]      FIG. 3  is an enlarged partial view of an end portion of the outer casing part and illustrating the provision of a distinct and additional positioning hole; 
           [0018]      FIG. 4  is a further partial view of an end portion of the outer casing part and illustrating a unique end serration configuration; 
           [0019]      FIG. 5  is an enlarged partial end view of a substantially “T” shaped hook portion associated with the intermediate positioned actuating plate; and 
           [0020]      FIG. 6  is a fragmentary view of a tab shaped and extending side edge associated with the inner casing part. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Referring to  FIG. 1 , an exploded view is illustrated generally at  10  of a latch assembly with adjustable backset according to the present inventions. As will be subsequently described, the present invention discloses a novel and adjustable backset latch and combination latch bolt assembly for incorporating into a handle activated and door locking assembly. 
         [0022]    Although not shown, the latch assembly is incorporated into a door and door jamb application, and whereby suitable recess configurations are pre drilled or otherwise pre formed between the door and opposing door jamb. It is further understood that all of the components comprising the latch, backset and latch bolt are preferably constructed from a durable and high strength steel or other metal. 
         [0023]    As shown in  FIG. 1 , a handle  12  is rotatably mounted to a housing, shown as being generally circular in shape at  14 . As also shown in the rotated perspective view of  FIG. 1A , a spindle  16  extends from the handle  12  in rotatably slaved fashion. A pair of fixed mounting rods  18  and  20  further extending from the housing  14  in parallel fashion relative to the spindle  16 . As is best shown in  FIG. 1A , the spindle  16  includes a pair of keyed openings  22  and  24 , these as will be subsequently described engaging portions of the backset latch assembly and for the purpose of actuating the retraction of the lock cylinder bolt. 
         [0024]    As clearly referenced in  FIGS. 1 and 1A , a backset subassembly is illustrated in exploded manner and arranged in substantially perpendicular extending fashion relative to the spindle  16  and mounting rods  18  and  20 . As will be described subsequently in further detail, the backset is operatively engaged by the handle  12  and, in turn, actuates a latch bolt assembly (see as generally shown at  26  in  FIG. 1 ) to linearly withdraw in a direction towards the backset, upon rotation of said handle. 
         [0025]    In relevant part, the backset assembly includes an inner casing part  28  and an outer spaced apart and aligning casing part  30 . As will be described in additional detail, a linearly actuating plate  32  and a follower plate  34  are sandwichingly engaged between the inner  28  and outer  30  casing parts. 
         [0026]    Each of the inner  28  and outer  30  casing parts have a specified shape and size and include a centrally located and aligning opening (see arcuate shaped openings defined by inner boundary edges  36  and  38 ) and through which extends the spindle  16 . In combination, first and second pairs of individual positioning and aligning holes (see at  40  &  42  and at  44  &  46 ) are arranged on opposite sides of the central aligning openings for parts  28  and  30 , and for receiving the mounting rods  18  and  20  therethrough. A third pair of apertures  48  &  50  are further illustrated in association with the casing parts  28  and  30  and are positioned in likewise aligning fashion between the first pair of apertures  40  &  42  and the arcuate central openings  36  and  38 . 
         [0027]    The actuating plate  32  further includes a lengthwise extending and open interior  52  for facilitating passage therethrough by the spindle  16  and mounting rods  18  and  20 . The actuating plate  32  further exhibits an extending end with oppositely arrayed hook portions  54  and  56  (see also enlarged view of  FIG. 5 ), and for engaging the latch bolt assembly  26 . 
         [0028]    The follower plate  34  seats between the casing parts  28  and  30  and in sliding fashion against the actuating plate  32  to facilitate extension and retraction of the latch bolt assembly  26 . The follower plate  34  is further linearly repositioned between shorter and longer backset positions relative to the casing parts. To facilitate such action, the follower plate  34  includes a first edge extending and arcuate recess  58  terminating, at opposite ends, in a pair of teeth  60  and  62  (these being dimensioned such as to receive the key apertures defined in circumferential offset along the spindle  16  as previously described at  22  and  24 ). A second opposite edge including a likewise central extending and arcuate recess  64 . 
         [0029]    In a shorter backset position, a selected on of the teeth  60  or  62  engages the rotating spindle, simultaneously with contacting protrusions associated with end legs, see at  66  and  68  of the actuating plate  32  extending opposite the hook portions  54  and  56  thereof, and to indirectly retract the bolt assembly  26 . In the longer backset position, the follower plate  34  is moved longitudinally relative to the inner  28  and outer  30  casing parts, such that the first arcuate recess  58  is positioned in alignment with a selected pair of aligning and individual positioning holes (e.g. at  40  and  42 ) through which a selected mounting rod  18  extends, and further such that the second arcuate recess  64  of the follower plate  34  operates as an axle bearing against the spindle  16  in order to rotate at a fixed point. 
         [0030]    Additional features associated with the backset includes the follower plate  34  exhibiting a pair of bead shaped protrusions, see at  70  and  72  in the rotated view of  FIG. 1A , these extending from an exposed face thereof. A pair of angled edge tabs  74  and  76  are associated with the outer casing part  30  and contact the bead shaped protrusions  70  and  72  to define a linear end stop position of the follower plate  34  within the backset subassembly. 
         [0031]    The actuating plate  32  further exhibits a specified and generally flattened configuration with the opposite extending hook portions  54  and  56  each further including a substantially rectangular shape. A pair of inner arcuate edges, see at  78  and  80  as best shown in  FIG. 5 , are associated with each hook portion  54  and  56 , thereby defining a seating location for receiving appropriate gripping components of the lock bolt assembly  26  (and as will be shortly described as including a gripping tabs associated with a stem portion of the retractable latch bolt). 
         [0032]    Additional features of the inner casing part  28  includes a pair of angularly extending side walls  82  and  84 , first and second pairs of finger portions  86  &  88  and  90  &  92  extending from first and second (typically end) locations of each of the side walls  82  and  84 . Reference is also made to the enlarged view of  FIG. 6  illustrating the shaping of selected finger gripping portion  90 . The outer casing part  30  further includes a substantially plate-shaped (i.e. flattened) configuration with side edge notches (see at  94  &  96  and  98  &  100 ), see also  FIG. 4 , these aligning and assembling with the finger portions  86 ,  88 ,  90  and  92  associated with the inner casing part  28  for seatingly engaging to the inner casing part in a desired spaced apart fashion. 
         [0033]    The inner casing portion  28  further includes an integral and forward extending blade portion  102 , this inserting through a slot shaped aperture  104  (see  FIG. 1A ) associated with an end face of the latch bolt  26  and providing coplanar support with the actuating plate  32 . A tab  106  (see  FIG. 1 ) extends from a forward location of the inner casing part  28  and engages an inside edge surface of the bolt slot aperture  104 . 
         [0034]    The outer casing part  30  further includes a first pair of linearly edge extending gripping portions, at  108  &  110  (again also  FIG. 4 ), and a second pair of angled and opposite edge extending gripping portions  112  &  114  (see also  FIG. 3 ) for securing the assembled backset in a desired mounting position within a door (not shown). A further pair of linearly edge extending gripping portions are also shown at  116  &  118  for inner casing part  28  and in order to further assist in securing in place the backset assembly. 
         [0035]    Additional features of the actuating plate  32  include its open interior (see as previously shown at  52 ) defining a larger interior aperture (see opposing inner walls  120 ) located approximate the end legs  66  and  68 . An interconnecting and narrowed aperture (see further opposing inner walls  122 ) extends forwardly in a direction towards the hook portions  54  and  56 . 
         [0036]    Referring now to  FIG. 2 , when viewed in combination with the perspective illustrations of  FIGS. 1 and 1A , an exploded illustration is shown of the latch bolt assembly  26  and which includes a cylinder shaped and interiorly open body  124 , within which is mounted a bolt  126  in spring biasing fashion. The bolt  126 , as known, exhibits a rounded arcuate outer profile along one edge which converges with a substantially straight edge to define a seating and opening preventative surface within a suitable door jamb mounted receptacle (not shown). 
         [0037]    A stem portion  128  ( FIG. 2 ) extends from the bolt  126  and includes a flattened forward end  130  which seats within an apertured interior  132  associated with the bolt  126  or can be otherwise integrally formed or mounted therewith. The stem  128  also includes gripping tabs  134  and  136 , these provided for seating and engaging the hook portions  54  and  56  of the actuating plate  32 , and for thereby translating the linear retraction of the actuator plate  32  (as influenced by the action of the spindle  16  upon the follower plate  34 ) to the bolt  126 . The end of the stem  128  opposite the bolt inserting end  130  is illustrated with a substantially “U” shaped configuration, see at  132 , it being understood that the shaping of the stem is dictated by dimensional considerations associated with the lock cylinder body interior  124  and the inserting components of the actuating plate  32  hook portions  54  and  56  and the blade portion  102  of the inner casing part  28 . 
         [0038]    Referring again to  FIG. 2 , a primary spring  134  is positioned so as to be supported upon a surface of the stem portion body  128  and which biases at opposite ends with the bolt  126  and the cylinder body  124  interior, so as to influence the bolt  126  in an outward direction relative to the cylinder shaped body  126 . An anti-theft pin  136  is supported in both individually retractable and slaved fashion relative to the bolt  126 , this feature accomplished by the keyed arrangement established between an underside projection  138  of the pin  136  and an end-stop  140  defined upon an upper surface of the bolt  126  and communicating with guide surfaces for seating thereupon the pin  136 . Upon mounting the pin  136  to the bolt  126 , the pin is permitted to selectively and individually displace in a direction towards the bolt cylinder  124  (relative to the main bolt  126 ) while being slaved for concurrent inward displacement along with the bolt  126  and as a result of its end stop  140  catching the pin underside projection  138 . thereby preventing the, a secondary spring supported upon opposing shaft portions associated with said anti-theft pin and a further pin mounted to an inside end surface of said open body. 
         [0039]    The latch bolt assembly further includes a disk portion, see at  142 , this being insertable within the open end of the cylinder shaped body  124 . A pair of circumferentially spaced apart end stops are shown at  144  and  146  (see in phantom in  FIG. 2  as well as in  FIG. 1 ) associated with intermediate inner locations of the open body  124 , these abutting lower edge locations of the insertable disk portion  142 . A cross wise slot is defined within and extends along the disk portion  142 , from an opposite top edge thereof, and defines first locations (see at  148  and  150 ) for engaging the extending stem gripping portions  134  and  136 , as well as a second location (at  152 ) for permitting passage therethrough of said anti-theft pin  136 . 
         [0040]    A secondary shoulder plate, at  154 , is supported upon a surface of the bolt retracting stem portion  128 , and for guidably supporting a secondary spring  156  which is secured at opposite ends to aligning and seating locations associated with both the anti-theft pin  136 , at  158 , as well as with a pin  160  mounted in extending fashion to an end wall surface of the bolt cylinder  124 , and through which the slot shaped aperture  104  is defined. A support plate  162  is secured in integrally extending fashion relative to the open end of the bolt assembly body  124 . A face plate  164  is sandwichingly engaged against the underlying support plate  162  and further defines an interior aperture  166  ( FIG. 2 ) for permitting passage therethrough of said bolt and anti-theft pin, as well as additional fastener mounting apertures  168  and  170  positioned astride the pin passage aperture  166 . 
         [0041]    Having described my invention, other and additional preferred embodiments will become apparent to those skilled in the art to which it pertains, and without deviating from the scope of the appended claims.