You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
PRIORITY 
     This application claims priority from U.S. Provisional Application No. 60/956,007, filed Aug. 15, 2007, the disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to an improved cylinder lock assembly. In particular, the present invention discloses a cylinder lock assembly that maintains a rotational coupling between a cylinder plug and a tailpiece in the event that the connection between them is forcibly breached. 
     2. Description of the Related Art 
     Cylinder lock assemblies are known in the art. In general, a cylinder lock assembly may comprise a cylinder plug and a tailpiece. The tailpiece is normally operatively coupled to a deadbolt, latch or the like on one end and to the cylinder plug on the other end, thereby coupling the cylinder plug to the deadbolt or latch. When the cylinder plug is rotated—e.g., by inserting and turning an appropriate key—it causes the tailpiece to rotate, which then causes a reciprocal retraction or extension of the deadbolt or latch. Typically, the cylinder plug, and therefore the tailpiece, can only rotate when the proper key is inserted into the plug. A problem associated with this kind of lock, however, is that a tailpiece may be made to rotate independantly of a cylinder plug by forcibly disconnecting the without the insertion of the proper key. 
       FIG. 1  shows a conventional cylinder lock assembly. The lock includes a cylinder plug  10  that is rotatably held within a housing (not shown) and includes a front end  14  and a rear end  12 . Exemplary cylinder locks of the type shown are described in the following patents assigned to Medeco Security Locks, Inc.—the respective disclosures of which are hereby incorporated by reference: U.S. Pat. No. 3,499,302 Spain et al (1970) U.S. Pat. No. 3,722,240 Spain et al (1973), U.S. Pat. No. 4,635,455 Oliver (1987), U.S. Pat. No. 5,289,709 Field (1994), U.S. Pat. No. 5,419,168 Field (1995), U.S. Pat. No. 5,570,601 Field (1996), U.S. Pat. No. 5,615,565 Field (1997), U.S. Pat. No. 6,023,954 Field (2000), and U.S. Pat. No. 6,477,875 Field et al. (2002). 
     As is conventional with cylinder locks of the type shown, cylinder plug  10  may include a plurality of radially arranged tumbler shafts  16  for receiving tumbler pins (not shown). A tailpiece  20  is connected to the rear end  12  of the cylinder plug by means of screws, bolts, or other suitable fasteners  1  extending through fastener holes  22  of a tailpiece retainer (retainer plate)  18  and into a fastener-receiving hole  24  formed in the cylinder plug  10 . The cylinder lock is operated by means of a key (not shown) inserted into a keyway opening at the front end  14  of the cylinder plug to thereby rotate the cylinder plug  10  about its longitudinal axis within the housing. Rotation of the cylinder plug  10  causes a corresponding rotation of the tailpiece  20  and tailpiece retainer plate  18 . The tailpiece  20  is coupled to a bolt or a door-latching mechanism (e.g., a lockset) in a known manner to cause reciprocal retraction and extension of the bolt or latch due to the rotation of the tailpiece  20 . 
     It has been suggested that the cylinder lock shown in  FIG. 1  can be breached by inserting a thin rigid object (e.g., a punch) into the keyway, such that the object extends through the rear end  26  of the keyway and against the retainer plate  18  or the end of the tailpiece  20 , and thereafter applying a sharp impact force to the rigid object, thereby shearing or otherwise disabling the fastener(s)  1  connecting the tailpiece retainer plate  18  to the cylinder plug  10 . With the tailpiece retainer plate  18  disconnected from the cylinder plug  10 , the tailpiece retainer plate  18  and the tailpiece  20  can be rotated independently of the cylinder plug  10 . Accordingly, if a narrow tool can be inserted into the keyway to grasp and rotate the tailpiece retainer plate  18  and tailpiece  20 , the bolt or door latching mechanism can be retracted without rotating the cylinder plug  10 , and thus the lock can be bypassed without a key. 
     Thus, there is a continued need for new and improved cylinder lock assemblies that prevent the deadbolt or latch from being operated even when the tailpiece has been forcibly disconnected from a cylinder plug. 
     SUMMARY OF THE INVENTION 
     A goal of the invention is to improve the security of cylinder locks by enabling such locks to resist attacks, such as by a punch hammered through the keyway of the lock. Accordingly, aspects of the invention are embodied in a cylinder lock assembly constructed and arranged to maintain a rotational coupling between the cylinder plug and the tailpiece in the event the conventional connection between the plug and the tailpiece (e.g. screws, clips, caps, etc.) is forcibly breached. More specifically, aspects of the invention are embodied in a cylinder lock assembly which includes a rotational coupling element for rotationally coupling the tailpiece to the cylinder plug so that the tailpiece cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug when the assembly is installed, for example, in a door, and regardless of whether the tailpiece is normally connected to the cylinder plug. 
     In the context of the this disclosure, a distinction is made between (a) a “connection” between the tailpiece and the cylinder plug, such as the conventional connection described above in which the tailpiece is fixedly attached to the cylinder plug, and (b) rotational “coupling” provided in accordance with aspects of the present invention whereby, although not fixedly attached to one another, the tail piece and cylinder plug are physically engaged so that the tail piece cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug. 
     According to one embodiment of the present invention, a cylinder lock assembly includes a cylinder plug that is rotatable about its longitudinal axis, a tailpiece adapted to operatively couple the cylinder plug to a deadbolt or a door latch actuator and configured so as to rotate with the cylinder plug when the tailpiece is connected to the cylinder plug, and a coupling element rotationally coupling the tailpiece to the cylinder plug so as to prevent the tailpiece from rotating about the longitudinal axis of the cylinder plug independently of the cylinder plug when the tailpiece is not conventionally connected to the cylinder plug. 
     The coupling element may, for example, include one or more anti-rotation legs integrally formed with and extending from the tailpiece into openings formed in the cylinder plug. Alternatively, the coupling element may comprise a structural interface, such as a pin or projection extending from the tailpiece retainer plate. The assembly may include a tailpiece retainer cap as opposed to a retainer plate, and a structural interface rotationally coupling the retainer cap to the cylinder plug may include an anti-rotation pin or other extension projecting from the cylinder plug into an opening formed in the retainer cap or a flattened surface formed on a side of the cylinder plug that engages a mating flattened surface formed in the interior of the retainer cap. 
     According to another embodiment of the invention, a method is provided for rotationally coupling the tailpiece to the cylinder plug of a cylinder lock assembly comprising the step of providing a coupling element that is fixed with respect to the tailpiece and extends axially into the cylinder plug at a location offset from the longitudinal axis of the cylinder plug. 
     According to another embodiment of the present invention, a method for modifying a cylinder lock assembly includes securing a pin to the tailpiece retainer plate such that the pin extends in a generally axial direction with respect to the cylinder plug and inserting the pin into an axial hole formed in the cylinder plug at a location offset from the longitudinal axis of the cylinder plug. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further applications and advantages of various embodiments of the present invention are discussed below with reference to the following figures: 
         FIG. 1  is an exploded perspective view of a portion of a conventional cylinder lock assembly including a cylinder plug, a tailpiece for coupling the lock to a bolt or door latching mechanism, a fastener, and a tailpiece retainer plate. 
         FIG. 2  is an exploded perspective view of a portion of a cylinder lock assembly embodying aspects of the invention including a cylinder plug, a tailpiece with an extended, anti-rotation leg that is insertable into an off-center hole formed in the cylinder plug, a fastener, and a tailpiece retainer plate. 
         FIG. 3  is an exploded perspective view of the portion of the cylinder lock assembly of  FIG. 2  with the tailpiece retainer plate omitted. 
         FIG. 4  is top plan view of the portion of the cylinder lock assembly of  FIGS. 2 and 3  with the tailpiece retainer plate omitted and the anti-rotation leg partially inserted into an axial hole  36  in the cylinder plug that extends axially toward the front end of the cylinder plug and beyond a tumbler shaft  16  disposed closest to the rear end of the cylinder plug. The anti-rotation leg  32  extends axially toward the front end of the cylinder plug and beyond a tumbler shaft disposed closest to the rear end of the cylinder plug. 
         FIG. 5  is an exploded perspective view of a portion of a cylinder lock assembly embodying aspects of the invention including a cylinder plug, a tailpiece with two anti-rotation legs that are insertable into off-center holes formed in the cylinder plug. 
         FIG. 6  is top plan view of the portion of the cylinder lock assembly of  FIG. 5  with the two anti-rotation legs partially inserted into the cylinder plug. 
         FIG. 7  is an exploded perspective view of a portion of a cylinder lock assembly showing an alternative embodiment of the invention including a cylinder plug, a tailpiece, a tailpiece retainer plate, and an anti-rotation pin extending from the tailpiece retainer plate and insertable into an off-center hole formed in the cylinder plug. 
         FIG. 8  is an end view of a portion of an alternative embodiment of a cylinder lock assembly in which the off-center hole is in the shape of a rectangle. 
         FIG. 9  is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug and a tailpiece with an extended, anti-rotation leg that is insertable into an off-center slot formed in the outer surface of cylinder plug. 
         FIG. 10  is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug and a tailpiece with three extended, anti-rotation legs that are insertable into corresponding off-center holes formed in the cylinder plug. 
         FIG. 11  is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug, a tailpiece, a tailpiece retainer cap, and an anti-rotation pin that extends from the cylinder plug into an opening formed in the tailpiece retainer cap. 
         FIG. 12  is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug, a tailpiece, a tailpiece retainer cap, and an anti-rotation surface formed on the cylinder plug that engages a mating surface within the tailpiece retainer cap. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention may be embodied in many different forms, a number of illustrative embodiments are described herein with the understanding that the present disclosure is to be considered as providing examples of the principles of the invention and such examples are not intended to limit the invention to preferred embodiments described herein and/or illustrated herein. 
       FIGS. 2-10  show various embodiments of a cylinder lock assembly constructed and arranged in accordance with the aspects of the present invention to prevent the tailpiece  20  from rotating about the longitudinal axis of the cylinder plug  10  independently of the cylinder plug  10 , while the tailpiece is still engaged with the dead bolt or door latch, should the tailpiece retainer plate  18  (or other means for connecting the tailpiece to the cylinder plug) be disconnected from the cylinder plug  10 , for example, as described in the Background above. More generally, the cylinder lock assembly includes a rotational coupling element for coupling the tailpiece to the cylinder plug. 
     In accordance with a first embodiment of the invention shown in  FIGS. 2-4 , the cylinder lock assembly includes a rotational coupling element in the form of an anti-rotation leg  32  extending from a shoulder  34  of the tailpiece  30 . The tailpiece shoulder  34  is configured to engage with the slot  3  in the rear end  12  of the cylinder plug, thereby configuring the tailpiece  30  to rotate with the cylinder plug  10  when the tailpiece is connected to the cylinder plug. The anti-rotation leg  32  extends into an off-center axial hole  36  formed in the cylinder plug  10  and extends axially toward the front end of the cylinder plug and beyond a tumbler shaft disposed closest to the rear end of the cylinder plug. The axial hole  36  is at a location that is offset from the longitudinal axis of the cylinder plug  10 . In the illustrated embodiment, axial hole  36  is a round, oblong hole formed in the plug  10  and extends axially toward the front end of the cylinder plug and beyond a tumbler shaft disposed closest to the rear end of the cylinder plug. Alternatively, hole  36  may be circular or rectangular or any other shape that will accommodate the leg  32 . Also in the illustrated embodiment, the tailpiece  30 , shoulder  34 , and anti-rotation leg  32  comprise a single, integrally-formed component. One of ordinary skill in the art, however, would appreciate that the tailpiece  30 , shoulder  34 , and anti-rotation leg  32  need not comprise a single component and each could, for example, comprise a separate component. Similarly, while the tailpiece  30  and the tailpiece retainer plate  18  are shown as separate components, they could be an integrally-formed, unitary piece.  FIG. 3  shows the assembly without the tailpiece retainer plate  18  to avoid obscuring the view of the tailpiece  30 . 
     Should the tailpiece retainer plate  18  be disconnected from the cylinder plug  10  as a result of shearing or otherwise disabling the fastener(s)  1 , the tailpiece retainer plate  18 , being confined within the structure of the door in which the lock is installed (not shown), cannot be moved in an axial direction sufficiently far away from the cylinder plug  10  to fully withdraw the anti-rotation leg  32  from the off-center hole  36  formed in the plug  10 . Accordingly, as shown in  FIG. 4 , with a portion of the anti-rotation leg  32  inserted into the off-center hole  36  of the cylinder plug  10 , and with a portion of the tailpiece  30  engaged with a deadbolt or door latch actuator (not shown), the tailpiece  30  is not able to rotate about the longitudinal axis of the cylinder plug  10  independently of the cylinder plug  10 . More specifically, because the axis of rotation A 1  of the tailpiece  30  and the cylinder plug  10  (i.e., the longitudinal axis of the cylinder plug  10 ) is offset from the longitudinal axis A 2  of the anti-rotation leg  32 , the tailpiece  30  remains rotationally coupled to the cylinder plug  10 , even when the tailpiece  30  is disconnected from the end  12  of the cylinder plug  10 . 
       FIGS. 5 and 6  show an alternative embodiment of the invention.  FIG. 5  is an exploded perspective view of a portion of a cylinder lock assembly including a cylinder plug  10 , a tailpiece  35  with two anti-rotation legs  32   a ,  32   b  that are insertable into off-center holes  36   a ,  36   b  formed in the cylinder plug  10 . In the embodiment of  FIG. 5 , holes  36   a ,  36   b  are circular, but they could be oblong (as in  FIGS. 2 and 3 ) or rectangular or any other shape that will accommodate the legs  32   a ,  32   b .  FIG. 6  is top plan view of the embodiment of  FIG. 5  with the two anti-rotation legs  32   a ,  32   b  extending from the tailpiece  35  and partially inserted into the off-center holes  36   a ,  36   b  formed in the cylinder plug  10 . As shown in  FIG. 6 , with the anti-rotation legs  32   a ,  32   b  inserted into the off-center holes  36   a ,  36   b  of the cylinder plug  10 , and with a portion of the tailpiece  35  engaged with a deadbolt or door latch actuator (not shown), the tailpiece  35  is not able to rotate about the longitudinal axis of the cylinder plug  10  independently of the cylinder plug  10 . More specifically, because the axis of rotation A 1  of the tailpiece  35  and the cylinder plug  10  (i.e., the longitudinal axis of the cylinder plug  10 ) is offset from the longitudinal axes A 2  and A 3  of the anti-rotation legs  32   a  and  32   b , respectively, the tailpiece  35  remains rotationally coupled to the cylinder plug  10 , even when the tailpiece  35  is disconnected from the end  12  of the cylinder plug  10 . 
       FIG. 7  shows an alternative embodiment of the invention. The embodiment of  FIG. 7  includes a tailpiece  20  and tailpiece retainer plate  18 , with a rotational coupling element in the form of an anti-rotation pin  42  extending through the tailpiece retainer plate  18  into an off-center axial hole  46  formed in the cylinder plug  10 . It would be understood by one of ordinary skill in the art that the tailpiece  20  and the tailpiece retainer plate  18  may comprise separate pieces, as shown here, or a single, integrally formed piece. Thus, the anti-rotation pin  42  provides a structural interface between the retainer plate  18  and the cylinder plug  10  to prevent the tailpiece  20  and the retainer plate  18  from rotating independently of the plug  10  when a portion of the tailpiece  20  is engaged with a deadbolt or door latch actuator (not shown). As with the embodiment described above, even with the tailpiece retainer plate  18  disconnected from the end  12  of the cylinder plug  10 , the anti-rotation pin  42  cannot be fully withdrawn from the off-center hole  46 , and thus the tailpiece retainer plate  18  and tailpiece  20  remain rotationally coupled to the cylinder plug  10  such that the tailpiece retainer plate  18  and tailpiece  20  cannot rotate independently of the cylinder plug  10 . 
     Thus, a conventional cylinder-tailpiece assembly, such as shown in  FIG. 1 , can be modified in accordance with an aspect of the present invention to rotationally couple the tailpiece  20  to the cylinder plug  10  by drilling a hole  46  in the plug  10  at a location that is offset from the longitudinal axis of the cylinder plug, drilling an aligned hole in the tailpiece retainer plate  18 , and inserting a pin  42  through the tailpiece retainer plate and into the off-center hole  46 . 
     In an alternative configuration to that shown in  FIG. 7 , pin  42  may be replaced or assisted by an axially extending projection formed integrally with the tailpiece retainer plate and which can be inserted into a hole or other opening formed in the cylinder plug  10  at a location that is offset from the longitudinal axis of the cylinder plug. 
       FIG. 8  shows an alternative embodiment of the invention. This embodiment differs from others in that the circular or oblong hole  36  formed in the end  12  of the cylinder plug  10  is replaced with a rectangular hole  56 . Other shapes such as semicircular, oval, or polygonal—e.g., square, hexagon, octagon, triangle—may be used as well for the shape of the off-center hole  56 . Additionally, the hole  56  could be circular for a portion of its axial extent and rectangular or polygonal for a different portion of its extent. The anti-rotation leg  32  can be provided so as to have the same shape as hole  56 , in which case, for, e.g., a polygonal or semicircular hole, the leg  32  cannot rotate inside the hole  56  about axis A 2 . Similarly, an oblong hole that partially matches the shape of the leg, which will also result in the leg not being able to rotate within the hole. 
     As is shown in  FIG. 9 , in a further alternative embodiment, a blind, off-center anti-rotation hole formed into the end of the cylinder plug  10  is replaced by an axially-extending groove  66  formed in the outer surface of the cylinder plug  10 . When the anti-rotation leg  32 —or an anti-rotation pin  42  or an axial projection extending from the tailpiece retainer plate  18 —is positioned inside the groove  66 , the tailpiece  20  or  30  cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug. With a rectangular anti-rotation leg, as with anti-rotation leg  32 , having the same shape as the groove  66 , the anti-rotation leg  32  is unable to rotate within the groove  66 , thereby achieving an additional anti-rotation effect. As an alternative to the embodiment shown in  FIG. 9 , the cylinder plug may have two or more axially-extending grooves formed in the outer surface of the plug, and the tailpiece may have two or more anti-rotation legs, or pins, configured and arranged to extend into the grooves. 
       FIG. 10  is perspective view of a portion of an alternative embodiment of a cylinder lock assembly with three anti-rotation legs  32   a ,  32   b ,  32   c  extending from the tailpiece  37  and insertable into off-center holes  36   a ,  36   b ,  36   c  formed in the cylinder plug  10 . Hole  36   c  is an extension of the keyway (reference number  26  in  FIG. 1 ). So that the third anti-rotation leg  32   c  does not interfere with a key inserted into the keyway, it may be necessary to elongate the plug  10  (and thus elongate the keyway), for example, by forming the plug from a longer piece of cylindrical stock or by adding an extension piece  13  to a conventional-length plug. Extension piece  13  may, for example, be secured to the plug  10  by screw or other suitable fastener elements. 
       FIG. 11  is perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug  10 , a tailpiece  70 , a tailpiece retainer cap  76 , and an anti-rotation pin  82  that extends from the cylinder plug  10  into an opening  80  formed in the tailpiece retainer cap  76 . A rectangular tailpiece opening  78  is formed in the retainer cap  76 . Tailpiece  70  extends through the opening  78  from inside the cap  76 , and shoulders  74  formed on the tailpiece  70  prevent the tailpiece from passing completely through the opening  78 . Retainer cap  76  fits over the end of the cylinder plug  10  and is secured to the plug  10  by mechanical fasteners (e.g., screws) or by press fit or other suitable means. So that the retainer cap  76  does not interfere with any of the tumbler holes, it may be necessary to elongate the plug  10 , for example by forming the plug from a longer piece of cylindrical stock or by adding an extension piece  15  to a conventional-length plug. Extension piece  15  may, for example, be secured to the plug  10  by screw or other suitable fastener elements. The assembly includes a structural interface rotationally coupling the retainer cap  76  to the plug  10  to prevent the tailpiece  70  and the retainer cap  76  from rotating independently of the plug  10 . In the embodiment of  FIG. 11 , the structural interface is provided by the anti-rotation pin  82  inserted into a radially-oriented hole  84  formed near the end of the plug  10 . When the cap  76  is installed onto the end of the plug  10 , pin  82  extends into the opening  80  formed in the cap  76 . In the illustrated embodiment, opening  80  is a slot formed in the side wall of the cap  76  that extends to the end of the cap, but opening  80  may alternatively be a hole formed through the sidewall of the cap  76 . When the retainer cap  76  is unconnected to the plug  10 , the anti-rotation pin  82  extending through the opening  80  will prevent the cap  76  and the tailpiece  70  from rotating independently of the plug  10 . 
     As an alternative to the anti-rotation pin  82  shown in  FIG. 11 , the structural interface between the retainer cap  76  and the cylinder plug  10  may be provided by a radial fin or other projection extending from the cylinder into the opening  80  formed in the cap  76 . Furthermore, the assembly may include more than one pin, fin, or other projection extending from the plug and engageable with a corresponding opening formed in the cap. 
       FIG. 12  is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug  10 , a tailpiece  70 , and a tailpiece retainer cap  86 . In the embodiment of  FIG. 12 , the structural interface rotationally coupling the retainer cap  86  to the plug  10  is a flattened surface  88  formed in an extended portion  19  of the plug  10  which engages a mating flattened surface (not shown) formed in the interior of the cap  86 . Engagement of the surface  88  with a mating surface within the cap  86  will prevent the cap from rotating independently of the cylinder plug  10 . The assembly may include one or more additional flattened surfaces formed on the cylinder plug  10  which engage one or more corresponding mating surfaces formed in the interior of the cap. 
     Alternative structural interfaces for rotationally coupling the retainer cap to the plug may include mating grooves and ridges formed on the retainer cap and the cylinder plug or any other structural feature that will prevent the retainer cap from rotating independently of the cylinder plug. 
     Thus, a number of preferred embodiments have been fully described above with reference to the drawing figures. Other details of the embodiments of the invention should be readily apparent to one skilled in the art from the drawings. Although the invention has been described based upon these preferred embodiments, it would be apparent to those skilled in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.

Summary:
The present application relates to lock assemblies that provide a secondary coupling point, utilizing an anti-rotation pin or extended tailpiece leg or other method, which rotationally couples the tailpiece to the cylinder plug, thereby preventing rotation of the tailpiece independently of the cylinder plug. Therefore, a tailpiece within a bolt cam or other actuator used to withdraw a bolt or unlock a lockset cannot be rotated after the tailpiece connector connecting the tailpiece to the cylinder plug has been forcibly removed, severed, or destroyed.