Lock system
FIELD OF THE INVENTION 
     The invention pertains to the field of electronic combination lock systems. More particularly, the invention pertains to lock systems and related methods for providing controlled access to an area by means of limited use unlocking sequences. 
     BACKGROUND OF THE INVENTION 
     In the residential real estate industry, an obvious and major part of marketing a home for sale is the physical showing of property to a potential buyer by a sales broker or agent. If the owner is at home, entry can be readily achieved without the broker or agent needing a key. 
     In the vast majority of showings, the owner is not at home. The real estate agent has to somehow obtain a key. A key can be obtained from the listing broker to show the house. The key then has to be returned. This takes time and a great amount of effort. It presents a substantial logistics problem, time wise, to real estate brokers. It is this effort, known as &#34;key chasing,&#34; which needs to be eliminated, or measurably reduced. 
     Lock boxes or key safes now exist which house keys to a particular home offered for sale. The lock box is attached to the residence to allow a real estate agent to take a customer directly to the property. The lock box is unlocked with a special key issued to the agent. The house key can then be removed from the lock box and used to gain access to the property. A known type of lock box is illustrated, in U.S. Pat. No. 3,436,937 issued to Barrett. 
     With regard to known, key operated lock boxes, it is necessary for the key to be widely distributed. Typically, all of the agents in a given Real Estate Board would have a master key that unlocks all of the boxes used within the area of that Board. The number of keys in circulation might range from 20 to 400. As a result, the listing agent has little knowledge or control over whether the property is entered, when it is entered or by whom. 
     The broker is unable to report to the client as to the extent of interest in the property that he has been able to generate. Further, the large number of keys in circulation causes both the listing broker and the client to have concern for the security of the property. 
     Combination lock key boxes partially eliminate these problems if the internal combination is set to a new value each time the lock is installed at a different property. In this case, an agent wishing to enter a given property must communicate with the listing broker to determine the combination in use at a given property. 
     However, for subsequent entries to the same property, the agent already knows the combination and need not check with the listing broker to reenter. In addition, the combination for a given property is readily passed to other persons. Of course, these problems could be circumvented if the listing broker changed the combination after each time that the property was entered. This is an impractical solution however. This solution would entail as much work as the key &#34;chasing.&#34; 
     While the use of lock boxes is convenient and does eliminate &#34;key chasing,&#34; it does not afford the owner or his agent desirable control and information. If the residence was shown in the owner&#39;s absence, it may not be possible to determine who showed the property and when. Because known lock boxes fail to provide this information, and additionally raises security questions in owner&#39;s minds, many real estate offices prefer not to use the lock box as it now exists. This, creates, by necessity, the logistical problem of &#34;key chasing.&#34; 
     There thus continues to be a need for lock boxes or key safes which provide ready access to the stored key but which control initial access as well as repeated access by one or more parties to the stored key. Further, there continues to be a need for a key safe which can be opened without the need of a special key but still has the aforementioned access control capabilities. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention an apparatus and a method are provided for permitting controlled access to a region. The apparatus, a lock system, includes a multiple sided, generally rectangular shaped, housing. The housing defines an interior region therein. The interior region of the housing can be closed by a pivotably attached front panel. 
     A lock, affixed to the housing within the interior region, will lock the front panel to the housing until a valid input sequence has been entered. Input sequences can be entered into the lock system by means of a manually operable keypad affixed to the front panel. 
     The keypad includes 12 buttons. Ten of the buttons are numerically coded. Two of the buttons, the &#34;*&#34; and the &#34;#&#34; can be used for definition of selected special functions. 
     Affixed to an interior surface of the front panel is an electronic control system which can receive the input sequence from the keypad. The electronic control system is electrically coupled to a solenoid. The solenoid is an integral part of the lock mechanism. 
     The electronic control system can include a programmable processor as well as read only memory and random access memory. The processor can sense when an input sequence has been entered through the keypad. The entered input sequence is compared to a plurality of predetermined valid combinations. 
     If a match is detected between the input sequence and one member of the plurality of predetermined valid combinations, the processor can check to determine whether or not the matched combination has been enabled. If so, the processor energizes the solenoid. 
     The energized solenoid mechanically couples a locking plate member to a camming plate member within the lock mechanism. Once the two members are mechanically coupled together, the operator wishing to open the lock system can depress an unlocking bar which is carried by the housing. Depressing the unlocking bar deflects the coupled together camming member and locking member. This coupled together and deflected combination trips the lock mechanism. The front panel is forced open, away from its locked position, to an intermediate position by an internal biasing spring. The front panel can then be moved from its intermediate position to its fully opened position to provide access to the region within the housing. 
     In one embodiment of the present invention an object such as a key for a lock can be stored in the region within the housing. Once the lock system has been opened, the stored key can then be retrieved and used to unlock the related door lock. In another embodiment of the present invention, instead of opening the front panel on the housing, movement of the coupled together cam plate and locking plate can cause movement of a dead bolt. The dead bolt can be moved from a locked position to an unlocked position. In the unlocked position, a cabinet or door, previously locked closed, can then be opened to provide access to a region on the other side of the door. 
     Further in accordance with the invention, the programmable processor can automatically test each matched valid combination to determine whether or not that combination should be switched from an activated to a deactivated state. A prestored valid combination which has been set to a deactivated state will no longer actuate the solenoid. 
     Further, in accordance with the invention, a method of providing controlled access to a closed region is provided. The method includes a step of entering an input sequence. The entered input sequence is compared to the members of a plurality of predetermined valid unlocking sequences. If the entered input sequence matches one of the members of the predetermined plurality, the matched member of the plurality is tested to determine whether or not that sequence, though valid, has been enabled. 
     In the event that the matched sequence has been enabled an unlocking mechanism is actuated providing access to the selected region. In the event that the matched sequence has been deactivated the unlocking mechanism is not actuated. 
     Further, in accordance with the invention a method is provided for accessing rooms such as hotel rooms. The method includes providing a first enabling sequence which will enable a lock system for the room. A second sequence is then entered into the lock by the guest. The second sequence can be used to unlock the room as many times as desired during that period of time in which the lock system has been enabled. After a predetermined period of time, the lock system can be disabled and the unlocking sequence no longer functions to provide access to the room. 
     In an alternate to this method, the enabling sequence can be provided by hotel or motel management. The guest can then enter an arbitrary multicharacter sequence into the lock to be used to activate the lock during the stay. In this embodiment none but the entering guest would know what the multidigit operating sequence for the lock is during this stay. At the end of the stay the lock can be disabled. Subsequently a new multicharacter enabling sequence can be provided to the next guest assigned to that particular room. That subsequent guest could then enter another arbitrary multicharacter operating sequence. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which the details of the invention are fully and completely disclosed as a part of this specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a lock system in accordance with the present invention supported on a doorknob; 
     FIG. 2 is a perspective view of the lock system of FIG. 1 with a front panel pivoted to an open position and illustrating an interior region wherein a key can be stored; 
     FIG. 3 is an enlarged view, in perspective, partly broken away, illustrating various components of the lock system of FIG. 1; 
     FIG. 4 is an enlarged fragmentary side sectional view of the lock system of FIG. 1, taken along plane 4--4 of FIG. 3, illustrating the interrelationship of the components of the lock mechanism when the front panel is locked closed; 
     FIG. 5 is a sectional view taken along plane 5--5 of FIG. 4; 
     FIG. 6 is an enlarged fragmentary side sectional view of the lock system of FIG. 1 taken along plane 4--4 of FIG. 3 illustrating an initial coupling together of portions of the lock mechanism prior to unlocking the lock system; 
     FIG. 7 is an enlarged fragmentary side sectional view of the lock system of FIG. 1 taken along plane 4--4 of FIG. 3 illustrating manually induced movement of members of the lock system causing the lock mechanism to unlock the front panel; 
     FIG. 8 is an enlarged fragmentary side sectional view of a portion of the lock system of FIG. 1 taken along plane 4--4 of FIG. 3 illustrating the front panel in an intermediate position between its locked position and its fully opened position; 
     FIG. 9 is a fragmentary enlarged sectional view of the lock system of FIG. 1 taken along plane 4--4 of FIG. 3 illustrating relative movement of a doorknob clamping shackle with respect to the housing of the lock system; 
     FIG. 10 is an enlarged fragmentary front plan view, partly in section, illustrating relative position of the shackle and the housing such that the lock system can be removed from the supporting doorknob; 
     FIG. 11 is an enlarged, fragmentary, side sectional view of the lock system of FIG. 1 illustrating interaction of members of the lock mechanism as the front panel is being pivoted into its closed position; 
     FIG. 12 is a schematic diagram of a control system for use with the lock system of FIG. 1; 
     FIG. 13 is a block diagram of a sequence of steps involved in opening the lock system of FIG. 1; 
     FIG. 14 is an enlarged, fragmentary perspective view of an alternate embodiment of a lock system in accordance with the present invention; and 
     FIGS. 15-17 taken together illustrate in a side sectional view taken along plane 15--15 of FIG. 14, an operational sequence for unlocking the lock system of FIG. 14. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     With respect to the figures, a lock system 10 is illustrated hanging from a doorknob D. The lock system 10 includes a housing 12 and a cylindrical U-shaped shackle 14. The shackle 14 can be used to removably affix the lock system 10 to the doorknob D 
     The housing 12 is formed with four rigidly connected sides 12a through 12d and a fixedly attached back panel 12e. A front flange 12f is attached to front edges of each of the sides 12a-12d. 
     The housing 12 also includes a pivotably attached locking door 12g which also functions as a front panel member. The housing 12 defines an interior volume 15 bounded by the sides 12a through 12d, the rear panel 12e and the pivotably mounted door 12g. 
     Mounted on the door 12g is a 12-key keypad 16. Also mounted on the door 12g are a plurality of indicators 18. The indicators 18 can be implemented as low power light emitting diodes. The indicators 18 can be selected so as to emit light of different colors such as a yellow diode 18a, a green diode 18b and a red diode 18c. 
     Mounted on the front flange 12f is an elongated, manually operable, depressable, door opener 20. A battery recharging access port 22 is mounted on the bottom panel 12d. 
     In normal operation, the lock system 10 would be hung from a doorknob D as illustrated in FIG. 1. A key K for a lock associated with the doorknob D is stored in the interior region 15. When the door 12g is opened, as seen in FIG. 2, access is provided to the key K for purposes of opening the respective lock. 
     The shackle 14 has a first position where it is locked about the doorknob D, illustrated in FIG. 1. The shackle 14 is locked in position about the doorknob D, relative to the housing 12, by means of a retaining mechanism 24. The retaining mechanism 24 can be released when the door 12g is in the open position, as in FIG. 2. 
     Once released, the shackle 14 can be moved to a second position, illustrated in phantom in FIG. 1. The lock system 10 can be removed from the doorknob D for use elsewhere. 
     The lock system 10 includes a door latch or locking mechanism indicated generally at 26. The door latch mechanism 26 locks the door 12g closed until a valid combination has been entered, via the keypad 16, into the lock system 10. At that time the latch mechanism 26 is activated. The party entering the combination can then depress the elongated releasing bar 20. The door 12g is then pushed open slightly by an internal spring. The door 12g may then be manually opened the rest of the way to provide access to the key K. 
     The door 12g carries a set of locking pawls 28 which engage the latch mechanism 24 when the door is closed. Each pawl 28 includes a locking cam surface 28a and an unlocking cam surface 28b. 
     The locking pawls 28 are pivotably attached via a pivot shaft 30 to the door 12g. The locking pawls 28 are continuously forced to a first or locking position by springs 32. 
     The door 12g also carries electronic circuitry in a housing 34. The electronic circuitry is coupled to the keypad 16 and actuates the latch mechanism 26 in response to a valid combination having been entered via the keypad 16. The housing 34 could be plugable into the lock system 10 for easy replacement. 
     With respect to FIG. 3, the shackle 14 is slidably retained within the interior volume 15 by a flange 40 pivotably attached to the side walls 12c. An elongated end 42 of the flange 40 carries a locking wedge 44. The wedge 44 can engage a correspondingly shaped recess 46 at an end 14a of the shackle 14. 
     Cooperative interaction between the locking wedge 44 and the wedge-shaped recess 46 on the shackle 14 provides a strong yet simple mechanism for locking the shackle 14 about the doorknob D. The locking wedge 44 can be released by tripping a finger lug 42a and sliding the shackle 14 out of the top surface 12b of the housing 12. 
     When the locking wedge 44 is engaging the recess 46, a free end 14b of the shackle 14 extends through a boring 48 in the top surface 12b. The free end 14b is thus locked to the housing 12 when the locking wedge 44 engages the recess 46. In this condition, the shackle 14 does not rotate with respect to the housing 12. 
     When the finger lug 42a has been tripped permitting the locking wedge 44 to move away from the recess 46, the free end 14b can be withdrawn from the boring 48 to facilitate removal of the system 10 from the doorknob D. 
     The latch mechanism 26 includes a sliding cam plate 52, a rigidly mounted locking block 54 and a sliding locking plate 56. The rigidly mounted locking block 54 is fixedly attached to the interior of the housing 12. The sliding cam plate 52 an elongated, essentially rectangular member includes first and second slots 58a and b which permit linear movement thereof with respect to the locking block 54. Screws 60a and b which extend through the slots 58a and b slidably affix the cam plate 52 to the locking block 54. The locking plate 56 is slidably affixed to the locking block 54 in a similar fashion. 
     Biasing springs 62a and 62b bias the locking plate 56 upperwardly towards the top member 12D. A solenoid 64 is fixedly attached to and carried by the cam plate 52. The solenoid 64 could be covered by a protective housing if desired. 
     The cam plate 52 also carries a pair of spaced-apart cam surfaces 66a and 66b. The cam surfaces 66a and 66b slidably engage a corresponding elongated surface 20a on the depressable release member 20. As the release member 20 is depressed, the surface 20a slidably engages the cam surfaces 60a and b. This slidable engagement forces the slidable cam plate 52 downward toward the bottom member 12d of the housing 12. 
     The locking plate 56 is essentially rectangular in shape. A return or biasing spring 57 pulls the locking plate upwardly to the top panel 12b. A metal extension 70 is affixed to the plate 56 and is positioned over an end of the solenoid 64. As is discussed further subsequently, in response to energizing the solenoid 64, the upper portion 70 of the locking plate 56 is attracted toward the solenoid. 
     As a result of this attraction, the upper portion 70 moves toward the solenoid 64. The portion 70 can move into contact with an end of the solenoid 64. Movement of the upper portion 70 also causes the remainder of the sliding locking plate 56 to move downwardly toward the bottom surface 12D of the housing 12. 
     A battery 72 is mounted within the interior region 15 as a source of energy for the system 10. To frame the portion of the region 15 wherein the key K is stored, a premolded rectangular box 74 with an open front can be positioned within the interior region 15. The keybox 74 can be glued or affixed to the interior of the housing 12 in any convenient fashion. 
     FIGS. 4 through 8 illustrate a sequence of operations for opening the door 12g in response to a sequence or combination of characters having been entered through the keypad 16. In FIG. 4 the relative relationship of the various members of the system 10 prior to a valid combination having been entered is illustrated. In this state, sliding locking plate 56 is located at its uppermost position adjacent the top panel 12b in response to forces generated by the spring 57. Cam surface 56a carried by the sliding locking plate 56 is spaced-apart from unlocking cam surface 28b carried by the locking pawls 28. Further, locking cam surface 28a is lockingly engaged with a locking surface 54b of the block 54 for the purpose of keeping the door 12g closed. 
     Subsequent to a valid combination having been detected by the system 10, the solenoid 64 can be, as described below, energized. With respect to FIG. 6, in response to the solenoid 64 having been energized, the upper portion 70 of the slidable locking plate 56 moves downwardly in a direction 80 from the top panel 12B of the housing 12 until it contacts the solenoid 64. In this condition, the unlocking cam surface 56a comes into contact with the unlocking surface 28b on the locking pawls 28. Movement of the upper portion 70 and the locking plate 56 in the direction 80 stretches the biasing spring 57. 
     Once the valid, enabled combination has been detected by the system 10, in addition to energizing the solenoid 64 the green light emitting diode 18b, can be energized. Upon light from the green light emitting diode 18b being observed, the operator can then manually depress the release member 20 as illustrated in FIG. 7. In response to this depression, the surface 20a engages cam surfaces 66a and 66b. This slidable engagement forces the cam plate 52, and the sliding locking plate 56, both of which are temporarily coupled together by the solenoid 64, downwardly in the direction 80. 
     Movement in the direction 80 deflects the spring 52a causing it to bear against a cam surface 33 of the door 12g. In addition, the movement of the locking plate 56 in the direction 80 due to the interaction of the cam surfaces 56a and 28b deflects the locking pawls 28 downwardly also in the direction 80. This movement releases the locking pawls 28 from the fixed locking block 54. 
     As illustrated in FIG. 8, in response to the force from deflected release spring 52a the door 12g, which has now been released from the stationary locking block 54, rotates slightly in a direction 82 to a position intermediate its locked and its open positions. Movement in the direction 82 in response to the deflected spring 52a is great enough that the locking surfaces 28a of the locking pawls 28 no longer engage the locking surfaces 54b of the stationary locking block 54. The operator can then manually open the unlocked door 12g the remainder of the way. 
     With the door 12g opened, the operator can manually move the finger lug 42a thereby releasing the wedge 44 from the locking surface 46. The shackle 14 can then be moved in a direction 86 to release the system 10 from the doorknob D. Alternately, the key K can be removed from the keybox 74 and the respective lock unlocked. 
     To reclose the door 12g the operator merely rotates it, as illustrated in FIG. 11 in a direction 88 opposite the direction 82. The locking pawls 28 which carry the cam surfaces 28c will deflect and slide past the stationary locking block 54 due to interaction with the cam surfaces 54a. The system 10 will then return to its locked condition as illustrated in FIG. 4. 
     Control circuitry 100 for the system 10 is illustrated in the schematic of FIG. 12. The control circuitry 100 is carried within the container 34. The control circuitry 100 includes a programmable processor 102, type HD63705. The processor 102 includes read-only memory for program storage as well as storage for a plurality of predetermined valid combinations. The processor 102 also includes random access storage. 
     The processor 102 is electrically coupled to the keypad 16. The processor is also coupled to the plurality 18 of light emiting diodes 18a, 18b and 18c. 
     Driver transistors 104a, 104b and 104c provide drive current to the light emiting diodes 18 in response to control signals from the processor 102. The processor 102 is also coupled, via a driver 64a, to the electrical coil of the solenoid 64. 
     The circuitry 100 is powered by a rechargeable battery 106. The battery 106 can be recharged through the access port 22. A recharging and current limiting circuit 108 is provided between the access port 22 and the battery 106. Integrated circuit 110 is a low voltage detector. When the voltage of the battery 106 drops below a predetermined value, the red light emitting diode 18c is energized. The circuit 110 is a type S8053. 
     A switch 112 provides a signal indicating that the door 12q is open. Switch 112 can be located adjacent the base member 12d. 
     The processor 102 includes both read only memory for program storage as well as read only memory for storage of a plurality of valid combinations. In a preferred embodiment, a plurality of valid combinations such as 300 can be provided. Valid combinations could be represented by a 5, 6 or 7 digit number. It will be understood that the number of digits selected to represent a valid combination is not a limitation of the present invention. 
     In one embodiment of the invention, each combination is useable at any time but is useable only once. Once that combination has been used to open the lock system 10 it is disabled until the lock system 10 is reset using a provided reset function. 
     It will be understood that a variety of implementations are possible. The exact number of times a given combination may be used is not a limitation of the present invention. For example, each combination could be used twice if desired rather than just once. 
     The locking system 10 thus provides a convenient and cost effective way to control access to the key K stored therein. Each time a combination is issued to a party desiring access to the key K, that combination can be used just to provide one access. Subsequent accesses will require another combination. It is of further significance with respect to the present invention that all valid combinations are equivalent and any valid combination can be used at any time. 
     FIG. 13 is a flow diagram illustrating operation of the lock system 10. In an initial step, an operator depresses the &#34;*&#34; key on the keypad 16. The system 10 then illuminates the yellow light emitting diode 18a. This indicates that the system 10 is awaiting operator entry of a sequence or combination. The system 10 keeps track of the amount of time between entered digits. If more than ten seconds elapses between digits, the system automatically resets to its initial condition. Each time a character or digit is entered by depressing a key on the keypad 16, the green light emitting diode 18b flashes. 
     Upon receipt of a 5, 6 or 7 character key combination, the system 10 checks to determine whether of not a valid sequence has been entered. If not the system then checks to determine whether or not one of four valid function codes has been entered. 
     A valid sequence or combination is one which matches a member of a predetermined set of valid combinations. The predetermined set of combinations can be stored in memory or generated for comparison to entered combinations. 
     If a valid function code has been detected, the system 10 then flashes both the yellow and green light emitting diodes. The four available functions are: (1) a deactivate function which disables the prestored sequences or soft keys until the system 10 has been reactivated; (2) a reactivate function which reactivates the disabled soft keys; (3) a restart function which enables all of the used and disabled soft keys; and (4) a master function which always opens the door 12g and cannot be disabled. 
     In the event that a valid, lock opening, sequence or soft key has been detected, the green light emitting diode is turned on indicating to the operator to depress the bar 20. The front panel 12g then is unlocked and moves outwardly in the direction 82. The operator can then remove the key K and open the lock associated with the doorknob D. Upon completion of the visit, the key K can be returned to the key box 74 in the system 10. The front panel 12g can then be reclosed which automatically relocks it. 
     The predetermined list of one-use soft keys could be created and stored in memory when the processor 102 is programmed. Preferably, to minimize storage, the list of soft keys can be determined each time that an operator enters a potential lock opening combination. Preferably, the next soft key S n+1  can be determined as follows: 
     
         S.sub.n+1 =M of (S.sub.n *C)                               (1) 
    
     Where S n  is the previous valid soft key, a non-zero integer and C is an integer non-zero constant. The operation indicated by &#34;M of&#34; is a modulo 10 6  operation which limits a valid soft key to 999,999 or less. In Table 1, S 0  equals 100 and C equals 5. 
     
                       TABLE 1                                                     
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            S.sub.n                                                       
                  S.sub.n+1                                               
______________________________________                                    
S.sub.0        100     500                                                
S.sub.1        500     2500                                               
S.sub.2        2500   12500                                               
S.sub.3       12500   62500                                               
S.sub.4       62500   312500                                              
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     As each soft key is generated by equation (1), it can be compared to the entered combination. A match, provided that the key has not already been used, energizes the solenoid 64. 
     Once a soft key has been used, a record of that use is stored in non-volatile memory in the processor 102. That list of used combinations is checked after each match. If there is an entry in the non-volatile memory indicating prior use, the solenoid will not be engaged. 
     Use of the reactivate special function code will clear the list in volatile memory, thereby reactivating all of the valid combinations. The master function code can always be used to activate and unlock the system 10. 
     In the above described sequence, each soft key or predetermined combination is valid for use once. After a soft key has been detected, the system 10 generates an indicia which is stored in memory which indicates that that particular soft key has been used and is now deactivated. It will be understood that it would be within the spirit and scope of the present invention to permit a given soft key to open the lock system 10 more than one time before deactivating that soft key. In addition, it will be understood that the system 10 could be equipped with a two level soft key. A master level could enable one or more groups of prestored soft keys. Once enabled, a soft key from an enabled group could be used to open the lock system 10 one or more times. 
     FIG. 14 is an alternate embodiment of the present invention. In the embodiment of FIG. 14 an electronic lock system 120 in accordance with the present invention has been mounted in a door C. The system 120 includes a keypad 122 similar to the keypad 16. The lock system 120 also includes a manually depressable member 124. In contradistinction to the system 10, the system 120 does not include an openable front panel. As an alternate, the system 120 includes a dead bolt latch member 126. The dead bolt latch member 126 locks the door C closed against the supporting framework F. 
     As illustrated in FIGS. 15-17, when the system 120 detects a valid soft key that has been entered through the keypad 122 a light emitting diode corresponding to the light emitting diode 18b is turned on. Pressing the manually operable member 124 then moves the dead bolt latch from its locked to its unlocked position. The door C can then be opened providing access into the framework F. 
     When the door C is reclosed, the dead bolt latch 126 automatically relocks the door C closed. As in the case of the lock system 10, each time a valid soft key is used to open the lock system 120 the control circuitry checks to determine whether or not that soft key should be disabled. If so, that particular soft key will no longer function to open the lock system 120. 
     While the lock system 120 has been illustrated hanging by the shackle 14 from the doorknob D it will be understood that the exact mode of associating the lock system with a respective area is not a limitation of the invention. For example, the lock system 10 could be fixedly attached to the side of a building. Alternately it could be equipped with a hanger. The hanger can be positioned over the top of a door and the lock system 10 would then be removably affixed to the top section of a closed door. 
     As an alternate to the manually depressable member 20, a twistable knob could be used. Alternately, a slidable member rather than a depressable member could be used. 
     The lock system 10 or 120 can be used in any application wherein it is desirable to limit access to a region. If the lock system 120 is installed on a door C which is affixed to a parking lot money collection box daily access to the box can be provided to a collector. In this use of the lock system 120, the collector would receive a new combination each day and could only unlock the collection box once for that particular day. 
     Other uses of the present invention include access to a key for a rented vehicle. In general, the lock system 120 is usable wherever central control is required to provide access to a region. 
     In yet another installation, the lock system 120 could be utilized in hotels or motels. In this installation, the door C would correspond to a hotel or motel room door. An enabling sequence could be provided to a guest at check-in time. When the guest enters the enabling sequence through the keypad 122 the lock system is activated and can accept an arbitrary unlocking sequence to then be entered by the guest. In this mode of operation, the guest is free to specify an unlocking sequence to be used during this stay. This unlocking sequence can be used to operate the lock system 120 as many times as desired by the guest. At the end of the stay, the hotel or motel management can enter into the lock system 120 a disabling sequence. The lock will then stay disabled until a new enabling sequence is entered by the next guest. 
     Attached hereto as an Addendum is a listing of a computer program usable with the control system 100 to implement the flow diagram of FIG. 13. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims. ##SPC1##