Abstract:
A cylinder lock device including: a body housing having a bore, with a direction of elongation defining an axial direction for the device; a rotatable cylindrical plug in the bore, the plug having an axially extending key slot from at least one end of the plug; a plurality of driver pins configurable substantially perpendicular to the key slot and located within the body housing and substantially outside of the plug; a plurality of tumbler pins corresponding to and positionable substantially collinear with each one of the plurality of driver pins and substantially inside the plug, the tumbler pins displaceable by a key to bias the driver pins to enable rotation of the plug, the driver pins adapted to displace the respective tumbler pins; and a displacement mechanism being deployed within the body housing and adapted to displace the plurality of driver pins thereby selectively enabling rotation of the plug when no key is present in the slot.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to cylinder locks and, in particular, it concerns a cylinder lock apparatus that can be operated with or without a key. 
         [0002]    In a conventional mechanical cylinder lock, when an appropriate matching key is inserted into the cylinder lock, the key selves to mechanically align tumbler pins, and thereby allowing the cylindrical plug to be rotated freely to open the lock. Referring now to  FIGS. 1A and 1D , which are representations of a prior art cylinder lock  10 , with a key  12  inserted into the cylinder lock, and a door lock  15 . Door lock  15  includes, inter alia, a shaped slot  16  for receiving cylinder lock  10  and a door lock hole  16  through which a bolt (not shown) is inserted to secure the cylinder lock inside a door. Typically, door lock  15  is inserted into a hollowed-out edge of the door (not shown) and cylinder lock  10  is inserted through prepared holes in the door (not shown in the figure) and perpendicularly into and through shaped slot  16 , substantially along axis  18 . Door lock further comprises a locking tongue  19  Typically, cylinder lock  10 , when unlocked, serves to translate locking tongue  19  allowing the tongue to alternately inhibit and allow opening of the door. Typically, other cylinder locks having a cross-sectional profile and length substantially matching cylinder lock  10  may be replaced or retrofitted instead of cylinder lock  10 . Typical names/manufacturers of such cylinder locks include, but are not limited to: Euro Cylinders; Oval Cylinders; Asec 6-pin Euro profile; and Chubb M3, Overall lengths of such cylinders typically vary from approximately 70-95 mm. 
         [0003]    Reference is now made to  FIGS. 2A and 2B , which are cross sectional side views A-A of the cylinder lock shown in  FIG. 1A . The cylinder lock has a body housing  20 , which is bored from one end to the other end and a cylindrical plug  22 , which is fitted into the bore, and which may be rotated, as described hereinbelow A set hole  23  is located approximately in the middle of cylinder lock  10  to receive a bolt which is inserted into lock hole  16 , to secure the cylinder lock within door lock  15 , as described hereinabove in  FIG. 1B . Cylindrical plug  22  has a key slot  25  formed axially in cylindrical plug. Key  12  is inserted into slot  25 . A pin-tumbler set  30  is located in body housing  20  and in cylindrical plug  22  to serve to lock and unlock rotational movement of cylindrical plug  22 . Cylindrical plug  22  and a second cylindrical plug  31  may be mechanically coupled and uncoupled to a rotating tongue  35  by means of a selector mechanism (not shown in the figure), which allows either cylindrical plugs to rotate the rotating tongue, which in turn serves to move the locking tongue of the door lock (refer to  FIG. 1B ). The cylinder lock shown in  FIGS. 2A and 2B  is called a “blind cylinder”, meaning that a key can be inserted into only one side of the lock, with only one pin-tumbler set present, and that the other side of lock cannot accept a key. However, cylinder lock  10  may also comprise pin-tumbler sets in respective cylindrical plugs at both ends. 
         [0004]      FIG. 2B , which is a detailed view of  FIG. 2A , shows in greater detail pin-tumbler set  30  Pin-tumbler set  30  includes tumbler pins  32  and driver pins  34 , both of which are constrained to move generally perpendicularly to key  12 . Springs  33  typically serve to preload tile driver pins and the tumbler pins, displacing them towards slot  25 , thereby advancing part of one or more of driver pins  34  into cylindrical plug  22  through openings in the plug (not shown in the figure) and thereby locking rotation of cylindrical plug  22  when no key is present in the slot. Typically, key  12  is formed to fit the pattern and respective lengths of tumbler pins  32  When key  12  is fully inserted into slot  25 , the key presses tumbler pins  32  and driver pins  34  against springs  33 , alignedly inserting driver pins  34  into body housing  20 , and thereby enables rotation of the cylindrical plug. Whereas key  12  is shown inserted, with its wider traverse edge contacting the tumbler pins, another inserted orientation of key  12  may include its thinner traverse edge contacting the tumbler pins. Also, one or more additional sets of collinearly arranged tumbler pins (not shown) may be present, in the case of a master key, which is used to lock and unlock a number of such specially configured cylinder locks. 
         [0005]    A number of prior art electronic or combination electrical/mechanical lock systems allow a user to open a locked cylinder in a number of ways. In U.S. Pat. No. 3,889,501 by Fort, whose disclosure is incorporated herein by reference, a combination electrical and mechanical system is described. The system includes a lock having a fixed lock cylinder and a rotatable key slug. A first solenoid is employed in the current system to drive a lock pin, which is normally extended to lock the key slug. Upon insertion of an appropriately aperture-encoded key, light sources and detectors mounted in the lock are used in concert with appropriate circuitry to operate to the first solenoid to unlock key slug A second solenoid is operable, in response to an electrical power failure, to extend a latch pin. When the latch pin is extended a proper mechanical key is inserted and rotated, extension of the lock pin is prevented. A proper mechanical key can be inserted to move a plurality of spring loaded pin tumblers in the lock to enable rotation of the key slug during an electrical power failure. 
         [0006]    Aston, in U.S. Pat. No. 5,839,305 whose disclosure is incorporated herein by reference, discloses an electrically operable cylinder lock device, which includes a body with a bore housing a rotatable barrel, having a key slot. The device has an electromagnet, which is employed to interact with a detent bar, the detent bar positioned to alternately inhibit or enable, with the aid of the electromagnet, rotation of the rotatable barrel. Another embodiment disclosed by Aston has a microswitch which interacts with an inserted key and controls the supply of electrical power. 
         [0007]    While the prior art includes an array of combination electrical/mechanical lock systems of varying complexity, there is a need for an electronic or combination electrical/mechanical cylinder lock that, taking advantage of the inherent cylinder pin tumbler mechanism, can be unlocked or unlocked without the insertion of a key, while also functioning as a conventional lock operated with a key in case of an electrical power failure, 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is a combined electrical/mechanical cylinder lock that, taking advantage of the inherent pin tumbler mechanism, can be unlocked or unlocked without the insertion of a key, while also functioning as a conventional lock operated with a key in case of an electrical power failure. 
         [0009]    According to the teachings of the present invention there is provided, a cylinder lock device including: a body housing having a bore, with a direction of elongation defining an axial direction for the device; a rotatable cylindrical plug in the bore, the plug having an axially extending key slot from at least one end of the plug; a plurality of driver pins configurable substantially perpendicular to the key slot and located within the body housing and substantially outside of the plug; a plurality of tumbler pins corresponding to and positionable substantially collinear with each one of the plurality of driver pins and substantially inside the plug, tile tumbler pins displaceable by a key to bias the driver pins to enable rotation of the plug, the driver pins adapted to displace the respective tumbler pins; and a displacement mechanism being deployed within the body housing and adapted to displace the plurality of driver pins thereby selectively enabling rotation of the plug when no key is present in the slot. 
         [0010]    Most preferably, the key slot extends substantially radially to the side of the plug, forming a lateral opening in the plug and wherein the cylinder lock further comprises a fitted inhibitor adapted to cover the lateral opening so that tile plurality of displacer pins do not enter the lateral opening and thereby do not serve to inhibit disruption of rotation of the rotatable cylindrical plug. Preferably, the displacement mechanism is adapted to controllably displace the plurality of driver pins between a first state in which the plurality of driver pins are biased towards the key slot to provide a locked state and a second state in which the plurality of driver pins are aligned to allow rotation of the cylindrical plug. 
         [0011]    Typically, the displacement mechanism includes a first artificial muscle unit adapted to selectively displace the respective plurality of driver pins Preferably, the displacement mechanism includes an electromagnetic assembly, wherein the electromagnetic assembly comprises a controllable magnetic pole configuration to selectively displace the respective plurality of driver pins to allow the respective plurality of driver pills to be selectively displaced Typically, the displacement mechanism includes a magnetic unit, wherein the magnet unit includes a magnetic pole configuration to allow the respective plurality of driver pins to be selectively displaced. Most preferably, the displacement mechanism includes a mechanical linkage, the mechanical linkage driven by a linkage driver selected from the group consisting of: a second artificial muscle unit; a linear motor assembly, a rotational motor assembly, and an electromagnetic assembly. 
         [0012]    Most preferably, a rotatable tongue is positionable substantially axially with and at the interior end of the first rotatable plug and having an axial engager enabling the rotatable tongue to rotate with the first plug; a second rotatable cylindrical plug is in the bore, the axial engager enabling the rotatable tongue to rotate with the second plug; and a selector mechanism is adapted to selectively engage and disengage the axial engager when a key is present in the slot and when no key is present in the slot, the selector mechanism being adapted to preferentially engage the axial engager, enabling the rotatable tongue to rotate with the first plug. Preferably, the selector mechanism is further adapted to engage the axial engagement and to rotate the first plug when a key is present in the slot, after the rotatable tongue has been rotated by the second plug Typically, the selector mechanism is mechanically, electrically, and mechanically and electrically actuable. Most typically, the body housing dimensions are substantially identical to at least one of the following cylinder lock standards: Euro Cylinder; Oval Cylinder; Asec 6-pin Euro profile; and Chubb M3. 
         [0013]    There is further provided a cylinder lock device including a body housing having a bore, with a direction of elongation defining an axial direction for the device; a rotatable cylindrical plug in the bore, tile plug having an axially extending key slot from at least one end Of the plug; and a mechanically accessible handle permanently mechanically linked to tile plug at the end of the plug having the slot, the handle adapted to rotate the plug when the plug is freed to rotate and when no key is present in the slot. Most preferably, the handle is adapted to allow insertion and removal of a key from the slot. Preferably, the handle is further adapted to be hinged, so that the handle is stowed substantially perpendicular to axis of the plug and deployed substantially parallel to the axis of the plug. 
         [0014]    There is further provided a method of forming a cylinder lock device comprising the steps of: forming a bore in a body housing of the cylinder lock device, the body housing having a direction of elongation defining an axial direction for the device; inserting a rotatable cylindrical plug in the bore, the plug having an axially extending key slot from at least one end of the plug; configuring a plurality of tumbler pins in the plug, whereby a key displaces the tumbler pins to enable rotation of the plug; positioning a plurality of driver pins, corresponding to and substantially collinear with each one of the plurality of tumbler pins and locatable distally from the slot and from the plurality of tumbler pins, adapted to displace the respective tumbler pins; and deploying a displacement mechanism within the body housing to displace the plurality of driver pins thereby enabling or disabling rotation of the plug when no key is present in the slot. Most preferably, the method further includes the steps of: positioning a rotatable tongue substantially axially with and at the interior end of the first rotatable plug, and having an axial engager enabling the rotatable tongue to rotate with the first plug; inserting a second rotatable cylindrical plug in the bore, the axial engager enabling the rotatable tongue to rotate with the second plug; and configuring a selector mechanism to selectively engage and disengage the axial engager when a key is present in the slot and when no key is present in the slot, the selector mechanism preferentially engaging the axial engager, enabling the rotatable tongue to rotate with the first plug. 
         [0015]    There is further provided a method of forming a cylinder lock device comprising the steps of: forming a bore in a body housing of the cylinder lock device, the body housing having a direction of elongation defining an axial direction for the device; inserting a rotatable cylindrical plug in the bore, the plug having an axially extending key slot from at least one end of the plug; and configuring a mechanically accessible handle permanently mechanically linked to the plug at the end of the plug having the slot, whereby the handle serves to rotate the plug when the lock is unlocked and when no key is present in the slot. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0017]      FIGS. 1A and 1B  are representations of a prior art cylinder lock and a door lock, respectively; 
           [0018]      FIGS. 2A and 2B  are cross sectional side views of the cylinder lock shown in  FIGS. 1A and 1B ; 
           [0019]      FIG. 3  is an end view and a cross sectional view of a cylinder lock with magnetic displacement of the pin-tumbler set, in accordance with of an embodiment of the present invention; 
           [0020]      FIG. 4  is an end view and a cross sectional view of the cylinder lock of  FIG. 3  with magnetic displacement of the pin-tumbler set, in accordance with an embodiment of the present invention; 
           [0021]      FIGS. 5A and 5B  are end and cross sectional views, respectively of the cylinder lock of  FIG. 3 , with artificial muscle displacement of the pin-tumbler set showing an unlocked and locked state, respectively, in accordance with of an embodiment of the present invention; 
           [0022]      FIGS. 6A-C  are cross-sectional, representative, and cross sectional views, respectively, of the cylinder lock of  FIG. 3 , having a mechanical linkage assembly displacement of the pin-tumblers and having a cylindrical plug rotational handle, in accordance with embodiments of the present invention; 
           [0023]      FIGS. 7A and 7B  are schematic illustrations of a modified cylindrical plug and the key, in accordance with an embodiment of the present invention; 
           [0024]      FIGS. 8A-F  are schematic illustrations of exemplary configurations of a modified cylindrical plug, an inhibitor, and the inhibitor assembled onto the modified cylindrical plug, of an embodiment of the present invention; 
           [0025]      FIGS. 9A-C  are top, side and sectional views, and isometric illustrations including partially sectional views, respectively of a cylinder lock a selector mechanism, in accordance with an embodiment of the present invention; and 
           [0026]      FIG. 10  are isometric illustrations including partially sectional views of the cylinder plugs and the selector mechanism of  FIGS. 9A-C . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0027]    The present invention includes a lock apparatus that may be opened with or without a key and methods thereof. 
         [0028]    Reference is now made to  FIGS. 3 ,  4 ,  5 A,  5 B, and, which are end and cross sectional views of cylinder lock  110 , and to  FIGS. 6A-C , which are cross-sectional, representative, and cross sectional views, respectively, of cylinder lock  110 , in accordance with embodiments of the present invention. Apart from differences described below, cylinder lock  110  is generally similar to operation of cylinder lock  10  as shown in  FIGS. 2A and 2B , so that elements indicated by the same reference numerals are generally identical in configuration and operation. Embodiments of the current invention disclosed hereinbelow are directed to be generally replaceable to cylinder lock  10  and/or retrofittable to cylinder lock  10  in door lock  15  shown in  FIGS. 1A ,  1 B,  2 A, and  2 B. 
         [0029]    A pin displacement mechanism  136  is located in body housing  20  to displace tumbler pins  32  and driver pins  34 . Pin displacement mechanism  136  comprises one or more configurations as shown in  FIGS. 3 ,  4 ,  5 A,  5 B,  6 A, and  6 C, to preload driver pins  34  and tumbler pins  32  towards slot  25  when no key is present, thereby advancing part of one or more of driver pins  34  into cylindrical plug  22  and locking rotation of cylindrical plug  22 . Alternatively, pin displacement mechanism  136  may be activated to displace driver pins  34  into body housing  20 , thereby aligning them so as to enable rotation of the cylindrical plug, even when no key is inserted into slot  25 . 
         [0030]    The term “axial” and “axially”, as used hereinbelow and in the claims is meant to describe a configuration generally parallel to an axis. Additionally, the terms “open” and “closed, when used hereinbelow and in the claims in reference to a state of the cylinder lock, are meant to describe the respective states whereby plug rotation is enabled and disabled. 
         [0031]    Pin displacement mechanism  136  may comprise a magnetic unit  138 , as shown in  FIG. 3 . Magnetic unit  138  includes a series of rotatable permanent magnets (of which one is shown in the figure), corresponding to respective driver pins  34 . Dependant on the respective polarities of the individual magnets, respective magnets serve to displace respective driver pins towards and away from slot  25 . Polarities of respective magnets of magnetic unit  138  may be configured in a non-uniform configuration to obviate magnetic “picking” of cylinder lock  110 , such as when an external magnetic field is applied to tile cylinder, in an attempt to open the cylinder lock. Magnetic unit  138  includes a driver (not shown in the figure) for rotating respective magnets. 
         [0032]    Pin displacement mechanism  136  may alternatively comprise an electro-magnetic unit  146 , as shown in  FIG. 4 . Driver pin displacement functionality of electromagnetic unit  146  is generally similar to that described hereinabove for magnetic unit  138 , except that respective electro-magnets remain stationary. Polarities of respective electromagnets of electro-magnetic unit  146  may be changed and configured in a non-uniform configuration to obviate magnetic “picking” of cylinder lock  110 , such as when all external magnetic field is applied to the cylinder, in an attempt to open the cylinder lock. Magnetic unit  138  includes connections (not shown in tile figure) for operating tile respective electro-magnets. 
         [0033]    Another configuration of the pin displacement mechanism may be that of an artificial muscle unit  156 , as shown in  FIGS. 5A and 5B , showing respective locked and unlocked configurations of cylinder lock  110  Artificial muscle unit  156  may comprise one or more respective artificial muscles, which can individually displace one or more respective driver pins towards and away from slot  25 . Artificial muscle unit  156  includes connections (not shown in the figure) for operation. 
         [0034]    Pin displacement mechanism  136  may alternatively be a mechanical linkage  160 , as shown in  FIGS. 6A and 6C . In the example shown here, mechanical linkage  160  comprises: a pin driver arm  164 , which is Formed with tooth-like formation of respective plungers on one transverse edge of the arm, serving to contact corresponding driver pins; a linear driving arm  166  constrained to move generally parallel to the axis of cylindrical plug  22  and shaped to bear upon pin driver arm  164 ; and a linkage driver unit  167  which effects movement of linear driving arm  166 . 
         [0035]    Pin driver arm  164  and linear driving arm  166  are configured to enable controlled displacement of driver pins  34 , enabling locking and unlocking, as described hereinbelow. Pin driver arm  164  is constrained to move only towards or away from slot  25 , thereby displacing corresponding driver pins towards or away from slot  25 . The opposite transverse edge of pin driver arm  164  facing linear driving arm  166  has one or more diagonally formed bearing surfaces. Pin driver arm  164  has corresponding diagonal bearing surfaces along its upper transverse surface to bear upon the surfaces of pill driver  164 . Linkage driver unit  167  may comprise a linkage attached to a rotary motor, as shown in the figure. An alternative configuration for linkage driver unit  167  is a linear motor. Yet another alternative configuration for linkage driver unit  167  is an artificial muscle. Locked and unlocked configurations are shown in  FIG. 6C . 
         [0036]    Activation of pin displacement mechanism  136  as described hereinabove may be effected by direct wiring to a power and command unit outside of cylinder lock  110 . Alternatively, power for the pin displacement mechanism operation may be obtained from at least one on-board battery and activation may be through a wireless means. One example of wired and wireless activation is through a small number pad located near cylinder lock  110 . 
         [0037]    The embodiments described hereinabove allow for opening cylinder lock  110  and rotating the cylinder plug with a matching key, in a manner similar to that of a prior art cylinder lock, if necessary. However, when no key is present in slot  25  and pin displacement mechanism  136  is commanded to open cylinder lock  110 , there must be a means with which to similarly rotate cylindrical plug  22  and thereby open the door. 
         [0038]    Reference is now made to  FIGS. 6A-C , which are cross-sectional, representative, and cross sectional views, respectively, of the cylinder lock of  FIG. 3 , with a cylindrical plug rotational handle  169 , in accordance with of an embodiment of the present invention. Rotational handle  169  is mechanically attached to the exterior edge of cylindrical plug  22 . The rotational handle has a flattened wide shape and a hinge which allows rotational handle  169  to be deployed generally axially to cylinder lock  110 , thereby enabling rotation of opened cylindrical plug  22  in a manner similar to that of when a key is inserted into the cylinder lock. When not in use, rotational handle  169  is stowed substantially perpendicularly to the longitudinal axis of cylinder lock  110 , allowing access of a key to be inserted into slot  25 . 
         [0039]    Note that the slot in cylinder lock  110 , as shown in the end views of  FIGS. 3 and 4  and in  FIG. 5A , extends radially from approximately the center of cylindrical plug  22  to the periphery of the cylindrical plug, presenting an opening of the slot facing body housing  20 . As noted hereinabove, driver pins  34  and tumbler pins  32  move generally perpendicular to key  12 , and likewise perpendicularly to slot  25  When a matching key is inserted into cylinder lock  110  (thereby displacing driver pins  34  and tumbler pins  32  to allow rotation of the plug as described hereinabove), the key is then rotated, thus rotating cylindrical plug  22 . As cylindrical plug  22  is rotated, tumbler pins  32  are retained within the cylindrical plug by body housing  20  and driver pins  34  are retained in position within body housing  20  by the cylinder plug. Upon further rotation of cylinder plug, whereby slot  25  is presented to driver pins  34 , driver  34  pins continue to be retained due to the presence of the key in the slot. 
         [0040]    When no key is present in slot  25  and pin displacement mechanism  136  is commanded to displace driver pins  34  and tumbler pins  32  to allow rotation of the plug, cylindrical plug  22  may be rotated as described hereinabove Upon further rotation of the cylindrical plug, tie opening of slot  25  may be presented to driver pins  34 . Although no key is present in the slot, driver pins  34  are nonetheless retained in position by pin displacement mechanism  136 , as described hereinabove. However, if pin displacement mechanism  136  is presently commanded to displace driver pins  34  and tumbler pins  32  to disallow rotation of the plug, driver pins  34  may be undesirably driven into the opening of slot  25 , thereby disrupting rotation of cylindrical plug  22 . Similarly, when pin displacement mechanism  136  is commanded to displace driver pins  34  and tumbler pins  32  to allow rotation of the plug (i.e., with no key present, as described above), and following partial rotation of plug  22  (without the opening of slot  25  being presented to driver pins  34 ) displacement mechanism  136  may be presently commanded to displace driver pins  34  and tumbler pins  32  to disallow rotation of the plug. In this case, because driver pins  34  are retained in position within body housing  20  by the cylinder plug, rotation of the cylinder plug will still be allowed. Depending on the relative rotational position of the cylindrical plug, further rotation of the cylinder plug ill this case will result in either engaging driver pins  34  with tumbler pins  32  (thereby disallowing rotation of the cylinder plug, as desired) or in driver pins  34  being undesirably driven into the opening of slot  25 , thereby disrupting rotation of cylindrical plug  22  as noted hereinabove. A solution to the undesirable disruption of rotation is described hereinbelow. 
         [0041]    Reference is now made to  FIGS. 7A and 7B , which are schematic illustrations of a modified cylindrical plug  222  and key  12 , in accordance with an embodiment of the present invention. Note that modified cylindrical plug  222  is formed so that slot  225  does not present an opening at the periphery of the cylindrical plug, in contradistinction to the slot in cylindrical plug  22 , as shown in the end views of  FIGS. 3 and 4  and in Fig,  5 A, as previously noted. Modified cylindrical plug  222  may be used in embodiments described hereinabove of cylinder lock  110 , in place of cylindrical plug  22 , thereby obviating the problem of disruption of rotation previously noted. Sectional view B-B of  FIG. 7B  further illustrates that slot  225  does not present an opening at the periphery Of the cylindrical plug. Openings  231  are also shown in modified cylindrical plug  222 , for passage of the driver pins and the pin-tumblers. 
         [0042]    Reference is now made to  FIGS. 8A-F , which are schematic illustrations of exemplary configurations of a modified cylindrical plug  222 A and  222 B—both having slot opening  26 , an inhibitor  240  and  240 A, and the respective inhibitors assembled onto the respective modified cylindrical plugs, of an embodiment of the present invention Apart from difference described below, elements indicated by the same reference numerals of previous figures are generally identical in configuration and operation In the configuration shown in  FIGS. 8A-C  cylindrical plug  222 A has been machined or otherwise formed to reduce its diameter along much of it length to leave a ridge  238  along tile length of the cylindrical plug and a/lip  239  at one end of the cylindrical plug. Inhibitor  240  is typically formed from a thin, strong, metallic material and comprises openings  241 , which are formed to substantially match and align with openings  231 , and a space  242 , which is formed to substantially match and mate with ridge  238 . The thickness of the material forming inhibitor  240  is chosen so that when the inhibitor is  1 fitted onto cylindrical plug  222 A, the periphery of the inhibitor, ridge  238 , and lip  239  are all substantially flush. As shown in the  FIGS. 6B and 8C , inhibitor  240  is formed to fit snugly about the periphery of cylindrical plug  222 A and is maintained in position on the cylindrical plug by ridge  238 , and lip  239 . 
         [0043]    Referring to the configuration shown in  FIGS. 8D-F , cylindrical plug  222 B has been machined or otherwise formed to reduce its diameter along much of it length to leave a.lip  239  at one end. Inhibitor  240 A is similar to inhibitor  240  described hereinabove except that inhibitor  240  without tile space, presenting a complete peripheral surface. Inhibitor  240 A is formed to fit snugly about the periphery of cylindrical plug  222 A, having openings  241 , which are formed to substantially match and align with openings  231 . Inhibitor  240 A is maintained in position on the cylindrical plug by lip  239 . 
         [0044]    It should be noted that any configuration similar to the configurations of modified cylindrical plugs  222 A and  222 B and inhibitors  240  and  240 A, respectively, allowing effective covering of slot opening  26 , while not inhibiting movement of driver pins  34  into and out of openings  231 , and allowing substantially free rotation of the modified plug within tile cylinder body serves to solve the problem of disruption of rotation described hereinabove. 
         [0045]    As noted hereinabove, rotating tongue  35  (refer to  FIGS. 2A ,  3 ,  5 B, and  6 C) may be rotated by either of the cylindrical plugs when the cylinder lock is unlocked. The rotation may be controlled by means of a typical clutch mechanism, as known in the art. The control of rotation is advantageous, for example, in the case of a “blind cylinder”, where the blind end of the cylinder lock is typically towards the “inside”, meaning the side of the door which is not typically locked with a key. In the case of a conventional blind cylinder, the mechanism is designed to primarily allow rotation of the rotating tongue by the cylindrical plug from the inside, meaning the rotating tongue may be engaged when the cylinder lock is turned (unlocked) from the inside, even when the other cylindrical plug (outside) of the cylinder lock may be locked. When the outside cylindrical plug of a conventional cylinder lock is opened with a key, the key serves to engage the clutch mechanism so rotation of the rotating tongue by the cylindrical plug may be accomplished from the outside. However, because cylinder lock  110 , as described above, may be opened without the use of key  12 , a different clutch mechanism is employed, as described hereinbelow. 
         [0046]    Reference is now made to  FIGS. 9A-C  and to  FIG. 10 , which are top, side, and detailed sectional views, and isometric illustrations including partially sectional views, respectively, of a cylindrical plug assembly  301  and a selector mechanism  305 , in accordance with an embodiment of the present invention. Apart from differences described below, cylindrical plug assembly  301  comprises, inter alia, cylindrical plug  22  and second cylindrical plug  31 , as shown in  FIGS. 2-6 , so that elements indicated by the same reference numerals in  FIGS. 9A-C  and  FIG. 10  are generally identical in configuration and operation Selector mechanism  305  functions to alternately allow rotation of rotating tongue  35  by plug  22  or by plug  31 . Selector mechanism  305  comprises a selector plunger  306 , a key-side drive block  340 , a blind-side drive block  341 , a selector plunger face plate  355 , a coil spring  360 , key bearing plate  364 , and a leaf spring  366 . Key-side drive block  340  and blind-side drive block  341  are positioned generally concentrically to rotating tongue  35 , and they are radially constrained at the interior axial end of their respective plugs and may move in an axial direction, as indicated in  FIGS. 9C and 10 . Both drive blocks have two projecting drive tabs  368 , oriented typically 180 degrees from one another, whose purpose is to engage and rotate rotating tongue  35 . Leaf spring  366  serves to bias, key-side drive block  340  and blind-side drive block  341  towards the blind side of the cylinder lock (as shown in  FIGS. 9A and 9C ) so that if cylindrical plug  22  is open (i.e. the driver pins have been aligned to allow rotation of the cylindrical plug, as described in embodiments hereinabove and by using a matching key), key-side drive block  340  is normally engaged to allow rotation of the rotating tongue. If it is desired to engage and rotate rotating tongue  35  from the blind side of the cylinder lock, selector plunger  306  is depressed towards plug  31  Selector plunger face plate  355 , which is connected to selector plunger  306 , translates blind-side drive block  341  axially towards and against key-side drive block  340 , which in turn compresses leaf spring  366 . The resultant axial translation of blind-side drive block  341  engages it to allow rotation of the rotating tongue by cylindrical plug  31 . At the same time, key-side drive block  340  is disengaged Selector plunger  306  may activated manually, as described hereinabove, and it may be activated by electronic means, such as a motor, in which case it may also be commanded remotely, such as by a wire or wireless connection. 
         [0047]    Selector mechanism  305  may operated so that the selector plunger is depressed and plug  31  rotates the rotating tongue. However, if the selector plunger is released before the engaged blind-side drive block  341  is returned to its initial radial orientation, it is possible that the selector mechanism may be inadvertently held in a configuration with blind-side block  341  engaged, thereby disengaging key-side block  340 . Should it then be desirable to engage key-side block  340 , it would not be possible to do this due to the preload of tile leaf spring, maintaining blind-side block  341  in its engaged position. 
         [0048]    A solution to this problem is afforded by the structure of key-side block  340 , as shown in  FIGS. 9B and 9C  and  10 . Block slot  372  extends radially from the periphery of key side block  340 , positioned typically 90 degrees from the projecting drive tabs, as shown. The block slot is formed to align with slot  25 . When the key is inserted into slot  25 , in addition to serving to allow rotation of the cylindrical plug as described hereinabove, the end of the key enters the block slot and bears upon key bearing plate  364 , which is preloaded by coil spring  360 , serving to urge key-side block  340  against blind-side block  341 . Rotation of the key presently serves to rotate both key-side block  340  and blind-side block  341 . The blind-side block may thereby be disengaged by rotating the key back and forth as necessary, typically approximately 30 degrees in each direction. Following this, key side block  341  is engaged and may rotate rotating tongue as described hereinabove. 
         [0049]    Whereas the cylindrical plug assembly shown in  FIGS. 3-10  has tumbler pins  32  and driver pins  34  pins and a blind end, embodiments described hereinabove are likewise applicable for a cylindrical plug with tumbler and driver pin sets at both ends, mutatis mutandis. Whereas references hereinabove have been made to a cylinder lock as typically used in a door, embodiments of the current invention are likewise applicable to any configuration wherein a cylinder lock is typically applied. Such configurations may include, but are not limited to: drawers, windows, safes, gates, etc 
         [0050]    It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.