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You are an expert at summarizing long articles. Proceed to summarize the following text: 
This invention relates to an electronic lock assembly having a side bar plunger and solenoid cylinder locking mechanism. This application claims the benefit of U.S. Provisional Application No. 60/176,997 filed Jan. 19, 2000, herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     BACKGROUND OF THE INVENTION 
     In many environments, such as apartment houses, multi-family dwellings, condominiums or the like, the transient nature of residents present problems in using conventional locking mechanisms in association with a door having a latch which is operable from both sides of the door by means of a handle or the like. In such environments, keys usable to unlock conventional lockable latching mechanisms are easily replicated, thereby potentially compromising the security provided by the lockable latching mechanism. As tenants or occupants move from such an environment, a key or copy of the key can be retained, though the former tenant or occupant is no longer entitled to access thereto. Similarly, if maintenance or repair procedures require access by other personnel, maintaining security may again be compromised if keys are duplicated or not returned by the repair or maintenance personnel. Thus, security standards in such environments may require that the lock be removed in its entirety and replaced, or the lockable latching mechanism is swapped with another mechanism from another unit to ensure security. Another alternative is to have the lockable latching mechanism re-keyed such that the previous key will not operate the mechanism. In each of these situations, the replacement, re-keying or swapping of the lockable latching mechanism is costly, both in terms of expense and/or personnel resources, and/or presents a time consuming and inefficient process for ensuring security. 
     Attempts have therefore been made to provide enhanced security by providing an electronic lock which employs a programmable processor which can be programmed to only allow operation of the lock if a valid key is used. Thus, when a tenant moves from a premises, the electronic lock can simply be reprogrammed so that the old key will not operate the lock, thereby eliminating the need to replace or re-key the lock. Although electronic locks using card readers, key pads or contact activated data ports are known, various deficiencies in such electronic lock assemblies have been found, and such systems have generally been cost prohibitive or complex, thereby limiting widespread use in such environments. 
     SUMMARY OF THE INVENTION 
     Based upon the foregoing, the present invention is directed at an electronic lock assembly which uses a simplified locking mechanism, which is operable by a suitably programmed electronic key. It is therefore an object of the invention to provide an electronic lock mechanism which can be manufactured simply, is reliable in use, and is cost-effective to facilitate use in suitable environments, and to avoid the need to re-key or replace existing lock mechanisms while providing enhanced security. 
     The invention is directed to a cylinder type locking mechanism wherein a solenoid and plunger is provided to electronically lock and unlock a key cylinder, thereby allowing rotation of the key cylinder for unlocking of a locking mechanism when a suitably programmed electronic key is used in connection with the mechanism. A side bar and retaining spring engage the cylinder plug to prevent rotation thereof in the locked position with the side bar contacted by the plunger of the solenoid to prevent the side bar from moving until an authorized key is used to unlock the mechanism. 
     These and other aspects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective exploded schematic view showing an electronic deadbolt locking mechanism according to an embodiment of the invention; 
     FIG. 2 is a perspective schematic view of a cylinder housing assembly; 
     FIG. 3 is an exploded perspective view of the cylinder housing assembly as shown in FIG. 2; 
     FIG. 4 is a side elevational view of the cylinder plug according to this embodiment; 
     FIG. 5 is a cross sectional view taken along line  5 — 5  in FIG. 4; 
     FIG. 6 is an exploded view of the solenoid and plunger according to this embodiment; 
     FIG. 7 is a side elevational view of a sidebar according to this embodiment; 
     FIG. 8 is a cross sectional view taken along line  8 — 8  in FIG. 7; and 
     FIG. 9 is a top elevational view of an alternate embodiment of a solenoid/cylinder locking mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to FIG. 1, the present invention will be described in conjunction with an electronic deadbolt assembly  10 . As shown in FIG. 1, the deadbolt assembly  10  may include a face plate  12 , which will normally be visible from the edge of the door. A front case  14  may be joined to the front plate  12 , and a rear case  16  is provided in telescopic adjustable relationship to the front case  14 . A deadbolt  18  is provided in slideable relationship within the front case  14 , and is coupled to a swivel generally indicated at  20 . The swivel mechanism  20  may include a pair of ears  22  connected to a link  24 . The link  24  is connected to the bolt  18  in a suitable fashion, and operation of the deadbolt  18  between a fully extended position and a retracted position is provided by means of a spindle  26  in a known fashion. In general, spindle  26  is engaged between inner and outer cylinders, wherein upon rotation of the cylinders, spindle  26  rotates to cause corresponding movement of the swivel  22  and link  24  and movement of bolt  18  between extended and retracted positions. The structures of the front case  14 , rear case  16  and operation of the deadbolt is typical, and details of this construction and operation may be modified in accordance with known mechanisms. 
     The deadbolt assembly  10  as shown in FIG. 1 further comprising an outside housing assembly  30 , which includes an outside rose  32  and a lock cylinder or cylinder plug  34 , which will be described in more detail hereafter. The cylinder plug  34  includes a keyway  36 , into which an electronic key  130  is inserted for operation of the deadbolt assembly  10 . The deadbolt assembly  10  further comprises an inside turn assembly generally designated  50 , over which an inside rose  52  is positioned. A thumbturn  54  engages the inside turn assembly  50  such that operation of the thumbturn  54  will in turn cause rotation of a thumbturn extension  56  coupled to the inside turn assembly  50  having an outwardly extending portion  58  which engages spindle  26  in the deadbolt assembly. Thus, upon rotation of the thumbturn  54  on the interior of the door, rotation of the thumbturn extension  56  will in turn cause rotation of extension portion  58  so as to operate spindle  26  causing corresponding extension or retraction of the deadbolt  18  in a known fashion. The deadbolt  18  in its extended position engages a strike  60  positioned on the doorjamb, and an associated strike box  62 . A strike reinforcer  64  may be provided to enhance the structural integrity and security of the deadbolt latch. 
     It should be recognized that operation of a thumbturn in conjunction with the inside turn assembly  50  to selectively extend or retract the deadbolt  18  is generally known, and will not be described further. 
     Turning now to FIGS. 2 and 3, the outer housing assembly is shown in more detail. The outside housing assembly  30  includes a cylinder housing cap  70  having a hole  71  through which the cylinder plug  34  is exposed at the outside of the lock assembly. In this manner, keyway  36  will be exposed on the exterior of the lock assembly for access by an electronic key. The cylinder plug  34  is dimensioned to extend within a cylinder outside housing  72 , and is selectively rotatable within cylinder outside housing  72  by means of an authorized electronic key  130  positioned within keyway  36 . The electronic key  130  may include a data pin  146  extending from the front of a key housing to engage a data pin assembly  104  on the front of cylinder plug  34  as will be hereafter described in more detail. The cylinder outside housing  72  is removed from FIG. 2 for clarity of other elements situated within housing  72 . After insertion of the cylinder plug  34  into housing  72 , the rearward or opposing end of cylinder plug  34  disposed opposite keyway  36  engages a cylinder tailpiece  74  which is retained thereon by a retaining ring  76 . The cylinder tailpiece  74  engages the spindle  26  associated with the deadbolt latch assembly as described in FIG.  1 . In this manner, rotation of the cylinder plug  34  will in turn cause rotation of the spindle  26  and extends and retracts the deadbolt  18  as previously described. There also may be provided in association with the rearward end of the cylinder plug  34  a pick cap  78  which helps to prevent picking or tampering with the lock assembly. 
     Within the outside cylinder housing  72  is positioned a solenoid assembly generally indicated at  80 , including a solenoid plunger  82  which is spring biased to an outward position by means of solenoid spring  84 . As seen in FIG. 6, the solenoid assembly  80  may comprise a supporting frame  81  in association with a solenoid bobbin  83  to which electrical connection is made via pins  85 . The bobbin  83  is inserted and retained therein through an opening in the frame  81 . Other suitable configurations to provide solenoid assembly within the lock architecture would be recognized by those of ordinary skill, and are contemplated by the invention. Associated with the solenoid  80  is a flex assembly  86  which includes a flexible electrical connecting interface  88 , which carries electrical signals to a microprocessor  89  housed within the inside turn assembly  50  as described with reference to FIG.  1 . The flex assembly  86  also couples power to the solenoid  80  from a battery power source  91  housed within inside turn assembly  50  via clip (not shown) positioned at the end of flexible electrical connecting interface  88 . A stiffener  92  is provided to support various components in conjunction with the flex assembly  86 , including an LED  94 , a ground clip  96  and a data transfer spring  98 . A light pipe  100  is associated with the LED  94  to transmit light from LED  94  to the exterior of the electronic lock through an aperture  102  formed in the cylinder housing cap  70 . The LED will provide information to the user, as to whether an authorized key  130  is being used (green indicating light), or whether an unauthorized key has been inserted into the electronic lock assembly (red indicating light) as an example. The LED  94  can be multi-colored to allow various light signaling indications to the user. The ground clip  96  electrically grounds the assembly to the outside cylinder housing  72  when the flex and solenoid assembly is inserted into the outside cylinder housing  72 . The data transfer spring  98  extends to be electrically coupled in association with a cylinder data pin assembly  104  which is housed in association with the cylinder plug  34 . The cylinder pin assembly  104  extends to a position to be accessible at the front face of the cylinder plug  34  when positioned therein, through an access hole  106 . Preferably, the cylinder pin assembly  104  extends to be flush with the front face of cylinder plug  34 . In operation, when an electronic key  130  is inserted into keyway  36 , a contact pin  146  associated with the electronic key  130  contacts the cylinder pin assembly  104  which is in electrical wiper contact with the data transfer spring  98  to communicate data from the electronic key  130  through the flex assembly  86  to the microprocessor  89 . If an authorized key  130  is used, the microprocessor  89  will in turn send a signal through the flex assembly  86  to the solenoid assembly  80  to selectively withdraw the solenoid plunger  82  against the force of bias spring  84 . 
     As only an authorized electronic key  130  will provide data to initiate actuation of the solenoid by the microprocessor, rotation of the cylinder plug  34  is otherwise prevented by a rotation preventing member or sidebar  110 . The sidebar  110  includes a substantially flat major face  111  extending substantially parallel to the cylinder plug  34  and a sidebar spring  112  which biases the sidebar  110  into engagement with the cylinder plug  34 , to prevent rotation of the cylinder plug  34  until actuation of the solenoid and withdrawal of the plunger  82 . Sidebar spring  112  may comprise one or more of many types of springs and is not limited to the leaf spring type shown. Although not shown, a pair of coil springs could also be used as the sidebar spring  112 . As seen in FIGS. 4 and 5, the cylinder plug  34  includes an elongated slot  120  into which a bottom portion of the sidebar  110  is positioned. As seen in FIG. 8, the bottom portion of the sidebar comprises a contoured point  116 , which is substantially matched to engage the slot  120  formed in the plug cylinder  34 . As shown in FIG. 8, the contoured point  116  may be provided with angled portions, which in this embodiment are approximately 45°, to substantially match the configuration of the slot  120 , which in this embodiment is formed as an approximate 90° angled slot as seen in FIG.  5 . Upon attempting rotation of the cylinder plug  34 , and due to the configuration of the slot  120  in association with the bottom portion  116  of the sidebar  110 , the sidebar  110  will be urged outwardly from the slot  120  against bias spring  112 . To prevent such movement of the sidebar  110  unless an authorized key is inserted into the cylinder plug  34 , the plunger  82  of the solenoid engages the slot  114 , which extends into the flat major face  111 . As seen in FIG. 8, the slot  114  may also be configured to have angled sides at approximately 45°, into which the plunger  82  is positioned in its normally extended position. When the plunger  82  is positioned within the slot  114 , the sidebar  110  is not able to move outwardly relative to the slot  120  formed in the cylinder plug  34 . Thus, rotation of the cylinder plug  34  is prevented, thereby effectively locking the deadbolt mechanism, and not allowing retraction of the deadbolt  18  accordingly. When an authorized electronic key is inserted into the cylinder plug  34 , and a data signal is generated by a microprocessor to actuate the solenoid  80 , the plunger  82  is withdrawn from the slot  114  for a predetermined period of time. As a user rotates the authorized electronic key, the sidebar  110  will be urged out of the slot  120  in the cylinder plug  34  against the force of the bias spring  112 , to thereby selectively allow rotation of the cylinder plug and actuation of the deadbolt mechanism to retract the deadbolt  18  and allow opening of the door. After actuation of the deadbolt mechanism by an authorized electronic key, the cylinder plug  34  is rotated back to its initial position, and the sidebar spring  112  urges sidebar  110  back into slot  120  in the cylinder plug  134  and the solenoid plunger  82  into slot  114 , to thereby lock rotation of the cylinder plug at the home position until further actuation. 
     In this embodiment of the invention, upon insertion of an authorized electronic key  130  into the cylinder plug  34 , the microprocessor  89  will withdraw the solenoid plunger from the slot  114  for a predetermined amount of time. It may be desirable to provide a short delay occurring between actuation of the solenoid and return of the plunger to its normally extended position. The microprocessor  89  may therefore be programmed to cause retraction of the plunger to accommodate a slight delay which may occur between insertion of an authorized electronic key  130  and the user rotating the cylinder plug  34  for actuation of the deadbolt mechanism. If the user does not rotate the cylinder plug  34  after insertion of an authorized electronic key  130 , the system will time out and the plunger will return to its normally extended position to engage slot  114  and lock the mechanism accordingly. 
     In an alternative embodiment as shown in FIG. 9, the sidebar  110  is eliminated, and a solenoid  121  including a solenoid plunger  122  and bias spring  124  act directly in conjunction with the cylinder plug  34  to selectively lock rotation thereof. In this embodiment, the plunger  122  in its normally extended position will engage a slot  132  formed on the cylinder plug  34 , whereby rotation of the cylinder plug  34  is prevented until actuation of the solenoid  121  and retraction of the plunger  122  by microprocessor control. Upon actuation of the solenoid  121 , and retraction of the solenoid plunger  122 , the cylinder plug  34  is able to rotate to thereby operate the deadbolt mechanism in the desired manner, and upon return of the cylinder plug to its home position, the plunger  122  will again engage the slot formed in the cylinder plug  34  to lock rotation thereof. Other operational features in this embodiment may be similar to that described with reference to the previous embodiment. In both embodiments of the invention, the axis of the solenoid plunger is transverse and offset with to respect to the lock cylinder rotational axis, thereby effectively inhibiting rotation of the cylinder plug  34  until retraction of the solenoid plunger in the desired manner. 
     The lock mechanism according to the present invention provides an electronically actuable mechanism which is simple in construction and yet effective to provide enhanced security in a variety of environments. The mechanism can be used to replace conventional locking mechanisms, such that no other preparation of a door or the like is necessary, and allows the user to simply reprogram the mechanism to allow only authorized electronic keys to be used therewith in the desired manner. No rekeying or replacement of the locking mechanism is required to maintain security of the mechanism, thereby avoiding cost or labor associated with such procedures. The lock mechanism has a limited number of parts, and is extremely reliable, and is cost-effective in its implementation. 
     Whereas the invention has been shown and described with reference to particular embodiments thereof, it should be realized that there may be many modifications, substitutions or alterations thereto which are encompassed within the scope of the invention. The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

Summary:
The present invention is directed at an electronic lock assembly which uses a simplified locking mechanism, which is operable by a suitably programmed electronic key. The invention is directed to a cylinder type locking mechanism wherein a solenoid and plunger is provided to electronically lock and unlock a key cylinder, thereby allowing rotation of the key cylinder for unlocking of a locking mechanism when a suitably programmed electronic key is used in connection with the mechanism. A side bar and retaining spring engage the cylinder plug to prevent rotation thereof in the locked position with the side bar contacted by the plunger of the solenoid to prevent the side bar from moving until an authorized key is used to unlock the mechanism.