U.S. patent number 3,906,447 [Application Number 05/328,179] was granted by the patent office on 1975-09-16 for security system for lock and key protected secured areas.
Invention is credited to Paul A. Crafton.
United States Patent |
3,906,447 |
Crafton |
September 16, 1975 |
Security system for lock and key protected secured areas
Abstract
An electronic lock security system including a control console
and several remote secured areas, the entrance to each of the
secured areas being controlled by an electronic lock mechanism
responsive to a digital coded key. A key code is stored in each
lock mechanism and compared with the key code on a digital coded
key. If correspondence exists, entrance to the secured area is
granted. The lock mechanism stored key code can be changed in
response to an order code imprinted directly on the key. This
obviates the requirement of wired or wireless wave communications
links between the control console and each of the remote secured
areas. A further feature of the invention resides in the provision
of apparatus for automatically changing the stored key code at each
secured area after a variable predetermined time interval.
Inventors: |
Crafton; Paul A. (Potomac,
MD) |
Family
ID: |
23279857 |
Appl.
No.: |
05/328,179 |
Filed: |
January 31, 1973 |
Current U.S.
Class: |
235/382.5;
340/5.3; 340/5.67 |
Current CPC
Class: |
G07C
9/00571 (20130101); G07C 9/27 (20200101); G07C
9/21 (20200101); G07C 9/00904 (20130101) |
Current International
Class: |
G07C
9/00 (20060101); H04q 003/00 () |
Field of
Search: |
;340/149A,149R,147MD
;179/2CA ;235/61.7B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pitts; Harold I.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn and
Macpeak
Claims
What is claimed is:
1. A lock mechanism for generating an unlock trigger signal, said
mechanism including storage means storing a key code and comparison
means for comparing the stored key code with an applied key code to
cause the generation of the unlock trigger signal when the two key
codes coincide, the improvement comprising:
a machine readable card having formed thereon an order code and a
key code enciphered together,
means in said lock mechanism for reading said order code and key
code in enciphered form,
means for deciphering said order code and said key code,
first comparison means for comparing the order code with a lock
mechanism generated signal, and
means responsive to said comparison for storing the key code read
from said coded key in said storage means.
2. The lock mechanism of claim 1, wherein said order code
represents time, said lock mechanism including means for generating
a time representative signal, said first comparison means
comprising means for subtracting the time represented by said order
code from the time representative signal, said lock mechanism
further including threshold means responsive to the output of said
subtracting means for producing a key code accept signal when the
value of the output of the subtracting means is below the threshold
level of said threshold means.
3. The lock mechanism of claim 2, wherein said key has further
formed thereon an identification code, said lock mechanism further
including means for storing a lock mechanism identification code,
means for reading the identification code from the key, second
comparison means for comparing the stored lock mechanism
identification code with the read identification code and means for
blocking said key code accept signal when the stored lock mechanism
identification code does not correspond to the read identification
code.
4. The lock mechanism of claim 3, wherein said lock mechanism
further includes a lock bolt control circuit responsive to said
unlock trigger signal and a lock bolt responsive to the lock bolt
control circuit, said lock mechanism being coupled to an entrance
door of a room, said key having further formed thereon a time of
departure code, said lock mechanism including third comparison
means responsive to said time of departure code and lock mechanism
generated time representative signal for producing a key code
non-accept signal when said time representative signal is greater
than the time of departure code, means for storing a randomly
generated key code and means responsive to said non-accept signal
for resetting said key code storage means and entering said
randomly generated key code therein.
5. A security system for a lock mechanism comprised of a lock belt,
a lock bolt control circuit and unlock trigger command circuitry,
said unlock trigger command circuitry including means for storing a
key code and means for comparing the stored key code with a key
code read from a key, said security system including apparatus for
encoding said key comprising:
means for generating a random key code,
shift register means for storing the output of said generating
means,
means for storing an order code,
adder means for adding said order code and said key code,
pseudorandom sequence generator receiving said key code and the
output of said adder,
a first binary counter receiving the output of said adder to preset
said first counter,
means for simultaneously incrementing said first counter and
pseudorandom sequence generator until the binary counter reaches
its full count, and
key card writer means, for forming the number contained in the
pseudorandom sequence generator on a key card said number being
said order code and said key code enciphered together.
6. The apparatus of claim 5, wherein said order code represents
time, said apparatus further comprising a second binary, counter
clock means for incrementing the count in the binary counter at
predetermined time intervals, and means responsive to a request for
coding said key for transferring the contents of said counter to
said order code storage means.
7. The apparatus of claim 6, wherein said lock mechanism is coupled
to an entrance door of a hotel room further including means for
storing a room number, said adding means including means for adding
said room number to said order code, departure time and key code,
said key card writer means including means for forming the room
number on said key in decimal form.
8. The apparatus of claim 7, further comprising a central memory
means storing the key code and its associated room number, card
reader means for reading the codes on said key, comparison means
for comparing the key code and room number stored in said central
memory with the read codes from said key and means for producing a
billing accept signal when correspondence is determined.
9. The apparatus of claim 3, wherein said lock mechanism is
attached to a baggage locker.
10. The apparatus of claim 3, wherein said lock mechanism is
attached to an automobile starter circuit.
11. The security system including the apparatus of claim 5 wherein
said lock bolt control circuitry comprises:
means in said lock mechanism for reading the order code and the key
code as formed on said key card,
first comparison means for comparing the order code with a lock
mechanism generated signal, and
means responsive to said comparison for storing the key code read
from said coded key in said means for storing a key code.
12. The security system of claim 11 wherein the apparatus for
encoding further includes means for storing a departure time code,
and said lock bolt control circuit further includes means for
generating a time representative signal, second comparison means
for comparing the time representative signal with the departure
time code to produce a non-accept signal when a one-to-one
comparison exists, and means responsive to the non-accept signal
for changing the lock mechanism stored key code; said adder means
in said apparatus for encoding further including means for adding
said departure time code to said key code, said pseudorandom
sequence generator receiving as the output of the adder the sum of
the key code, order code and departure time code.
13. The apparatus of claim 6 further including means for storing a
departure time code, said adder means further including means for
adding said departure time code to said key code, said pseudorandom
sequence generator receiving as the output of the adder the sum of
the key code, order code and departure time code.
14. The apparatus of claim 13, further including first
transformation matrix means for scrambling said order code and
departure code prior to their application to the adder means,
second transformation matrix means for scrambling the output of the
adder means and key code prior to their application to the
pseudorandom sequence generator, and third transformation matrix
means responsive to the output of said adder means and pseudorandom
sequence generator for scrambling and means for applying the output
of said third transformation matrix means to said key writer
means.
15. The security system including the apparatus of claim 14 wherein
said lock bolt control circuitry comprises:
means in said lock mechanism for reading the scrambled order code,
departure code and key code as formed on said key card,
fourth transformation matrix means connected to said means for
reading and being the reverse of said thrid transfer matrix means
for unscrambling to provide outputs corresponding to the outputs of
said adder means and pseudorandom sequence generator,
second pseudorandom sequence generator receiving the second of the
outputs of said fourth transformation matrix,
third binary counter initially preset to its full count,
third comparison means for comparing the output of said third
binary counter with the first of the outputs of said fourth
transformation matrix,
means for simultaneously decrementing said third counter and said
second pseudorandom sequence generator until said third comparison
means produces an output,
fifth transformation matrix means connected to said second
pseudorandom sequence generator and being the reverse of said
second transfer matrix means for unscrambling to provide outputs
corresponding to the output of said adder means and said key
code,
subtractor means for subtracting the two outputs of said fifth
transformation matrix means to recover said order code scrambled
with said departure code,
sixth transformation matrix means connected to said subtractor
means and being the reverse of said first transformation matrix
means for unscrambling said order code and said departure code,
fourth comparison means for comparing the order code with a lock
mechanism generated signal, and
means responsive to said fourth comparison means for storing the
key code from said fifth transformation matrix means in said means
for storing a key code.
16. The security system of claim 15 further including means for
generating a time representative signal, fifth comparison means for
comparing the time representative signal with the departure time
code to produce a non-accept signal when a one-to-one comparison
exists, and means responsive to the non-accept signal for changing
the lock mechanism stored key code.
17. The security system of claim 11 wherein said order code
represents time, said apparatus for encoding further comprising a
second binary counter, clock means for incrementing the count in
the binary counter at predetermined time intervals, and means
responsive to a request for coding said key for transferring the
contents of said counter to said order code storage means.
18. The security system of claim 17, said lock bolt control circuit
including means for generating a time representative signal, said
first comparison means comprising means for subtracting the time
represented by said order code from the time representative signal,
threshold means responsive to the output of said subtracting means
for producing a key code accept signal when the value of the output
of the subtracting means is below the threshold level of said
threshold means.
19. The security system of claim 11, said encoding apparatus
further including means for storing a departure time code, said
adder means further including means for adding said departure time
code to said key code, said pseudorandom sequence generator
receiving as the output of the adder the sum of the key code, order
code and departure time code.
20. The security system of claim 19 wherein said reading means also
reads said departure time code, said lock bolt control circuitry
including means for generating a time representative signal, second
comparison means for comparing the time representative signal with
the departure time code to produce a non-accept signal when a
comparison exists, and means responsive to the non-accept signal
for changing the lock mechanism stored key code.
21. The security system of claim 20, said second comparison means
comprising means for subtracting the time represented by the
departure time code from the time representative signal, threshold
means responsive to the output of said subtracting means for
producing a non-accept signal when the value of the output of the
subtracting means is above the threshold level of said threshold
means.
Description
BACKGROUND OF THE INVENTION
At the present time, most secured areas such as rooms in hotels,
motels and office buildings, as well as baggage lockers and
ignition systems on rental cars, are provided with locks operated
by the mechanical interaction of a key and lock tumbler. In recent
years this ancient mechanical system has, to some extent, given way
to new electronic lock systems responsive to digitally coded keys.
In brief, the entrance to a secured area is controlled with an
electronic lock which includes an unlocked trigger command circuit,
responsive to a digitally coded key, a lock bolt, and an associated
lock-bolt control logic circuit responsive to an unlock trigger
signal. Included in the unlock trigger command circuit is a memory
storing a unique digital key code. When a coded key is inserted
into the electronic lock mechanism, the code on the key is read and
compared with the stored key code to determine correspondence. If
correspondence exists, an unlock trigger command signal is
generated to activate the lock bolt control logic to cause the lock
bolt to move to its unlocked position.
An example of an unlocked trigger control circuit, responsive to
digitally coded keys is described in U.S. Pat. No. 3,668,269 to
Edwin Miller. An example of a lock bolt control circuit, responsive
to an unlock trigger command and its associated lock bolt is
described in copending application, Ser. No. 84,085 by Stephen
Paull and Paul A. Crafton, filed Oct. 26; 1970 and assigned to an
affiliate of the assignee of the present invention.
Although the electronic key lock is indeed an important improvement
over the prior mechanical key and tumbler arrangement, many of the
security problems associated with the mechanical key and tumbler
arrangement remain with the electronic key lock. For example, with
respect to secured areas such as motels and hotels, where numerous
people have access to room keys, an unauthorized person might
easily gain access to a guest's room. For example, a hotel guest
may retain his key after checking out of the hotel and at a later
date illegally enter the room now occupied by another guest.
Attempts at solving this problem have involved changing the key
code which permits entrance into a secured area each time the
identity of the person authorized to enter the area is changed.
Examples of such systems can be found in U.S. Pat. No. 3,622,991 to
Lehrer et al., issued Nov. 23, 1971 and U.S. Pat. No. 3,662,342 to
Hedin et al., issued Feb. 16, 1971. In such prior art systems,
alteration of the stored key code at each of the remote areas
requires the use of wired or wireless wave communications links.
More specifically, a control console is connected to each of the
remote secured areas by way of wires. When a key code is to be
changed, the control console transmits over a wired or wireless
wave communication link an address signal identifying the secured
area at which the key code is to be changed along with a new key
code.
This type of system is extremely expensive and oftentimes not
feasible especially in older buildings where the installation of
additional electrical lines between some central control console
and each of the rooms of the building is not practical.
SUMMARY OF THE INVENTION
The present invention is directed to an improved electronic lock
security system.
In accordance with the teachings of the present invention, each
secured area has associated therewith an electronic lock mechanism
storing a unique key code. When an individual seeks to enter a
secured area, he presents a digitally coded key to the lock
mechanism wherein the key code on the key is compared with the
stored key code and if correspondence exists an unlock trigger
command is generated and applied to lock bolt control circuitry to
unlock the secured area. The key code stored in each lock mechanism
is easily and rapidly changed in response to an order code
contained directly on the digitally coded key. As a result, no
wired or wireless wave communication links are required between a
control console and the remote secured areas to accomplish the
selected changing of the stored key codes.
Imprinted on the key is an order code which, according to one
embodiment of the invention may be made to correspond to the time
the key is issued. The lock mechanism operates to compare the order
code on the key presented to it with the time of presentation, and
if the time difference is within a predetermined time interval, the
key code on the key is set into the lock mechanism. According to an
alternative embodiment of the invention, the order code corresponds
to the key code formerly set into the lock mechanism. The former
key code would have been stored, for example, in the central
control console for imprinting as an order code on the next issued
key for the secured area. Other order codes will be readily
apparent to those of ordinary skill in the art and, in any choice
of an order code, subsequent presentation of the key to this lock
mechanism causes the generation of an unlock trigger command.
A further feature of the invention, particularly applicable to
hotels and motels and the like, involves the generation of a time
of departure code. This time of departure code is imprinted on the
key when issued and entered into the lock mechanism when the order
code is presented thereto. When the departure time is reached, the
lock mechanism automatically changes at random the stored key code,
thus preventing the guest from entering the room.
A still further feature of the invention resides in apparatus,
responsive to the key code on a digitally coded key which permits
the hotel to verify the guest's authority to use the hotel's
restaurant, bar, shops, parking lot and other servide
facilities.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b are a detailed functional block diagram of the
control console of the instant invention;
FIG. 2 is a drawing of one example of a digitally coded key, which
may be used with the security system of the invention;
FIGS. 3a and 3b are a functional block diagram of the lock
mechanism of the instant invention; and
FIG. 4 is a block diagram illustrating the application of the
invention to a hotel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For ease in understanding the present invention, the security
system will be described with reference to its use in a hotel,
although it is to be understood that the security system is not
limited to this use alone, having a more general application. The
security system can be used to secure any area to which access is
given to many people, each for only short periods of time. Once a
person's permissible access time is over, he is barred from
entering the area. In addition to hotels, the present invention
will find application in securing baggage lockers, the ignition
lock system of rental vehicles, protected cargo areas and office
buildings.
A secured area is generally protected from unauthorized entrance by
a lock mechanism. Those with authority to enter are given a key
which gains them access to the secured area. Since keys are easily
reproduced, security against unauthorized entrance by a person
formally having authority to enter an area is very weak. The
quality of security increases greatly if the lock mechanism is
changed each time the identity of the authorized user changes, so
that even if he reproduces or keeps the key which formally admitted
him to the area, it becomes ineffective once his authorization has
expired.
The present invention, which involves an improved security system
of the type which uses electronic key locks, provides a reliable
and inexpensive technique for changing the key code stored in the
lock mechanism. As previously indicated, in electronic lock
systems, the stored key code is compared with the key code on a key
presented to the lock mechanism by the individual who desires
access to the secured area and if the two codes correspond,
entrance is granted. The present invention provides for alteration
of the stored key code in the lock mechanism by incorporating on
the key issued to the authorized user what is termed herein an
order code which, upon presentation to the lock mechanism, causes
the mechanism to be set to the key code on the key of the
authorized user. Thereafter, each time the user presents his key to
the lock mechanism, he is permitted to enter the secured area.
FIG. 1 illustrates the central control console of the invention
adapted for use in a hotel or motel. When a guest is assigned a
room, his room number is entered into the control console through
the decimal keyboard 100 which is coupled to the room number
register 11. For a three digit room number, the register may take
the form of three ten stage registers, each stage of a register
representing a different digit. Register 11 is coupled to a decimal
to binary converter 9, wherein the room number is converted into a
binary code. Subsequently the binary coded room number is stored in
binary register 6.
The guest key code, which will be imprinted on a room key and
subsequently presented to the lock mechanism at the guest's
assigned room, is a randomly generated number produced by a random
number generator 105 and stored in shift register 2. The key code
and the room number in binary form may be directly imprinted on the
room key. However, this would be detrimental to the security of the
area since the codes could easily be counterfeited and reproduced.
As an added measure of security, the room number and the key code
are enciphered in a manner to be described in detail below, prior
to its formation on the key.
The order code and its generation will now be described. The order
code, according to one embodiment is a time representative code and
corresponds to the time a guest checks in, that is, his arrival
time. At each lock mechanism there is provided, as described in
greater detail below, mechanism which compares the order code, that
is, the arrival time, with the time that the guest presents his key
to the lock mechanism located at the entrance to his room and if
the difference in time is within a predetermined time interval, the
new guest code is entered into the room lock mechanism. The measure
of time used in this system is advantageously not real time, but
rather non-real time corresponding simply to a count in a binary
counter. The counter may be preset to any arbitrary number with the
lock mechanisms at each of the hotel rooms synchronized to this
preset number. Each count in the counter corresponds to a known
unit of time, such as 1/60 of a second. The counter would have a
recycle time longer than the longest expected guest stay. For
example, the counter may be made to recycle once every two or three
years. A long recycle time is desirable when the security system is
provided with the optional time departure feature, wherein the
guest's check-out time is also set into the lock mechanism and at
this time, the key code assigned to the guest's room is
automatically changed so that this key will no longer gain him
entrance to the room.
The order code generator is comprised of binary counter 16 and
clock 17. Clock 17 may be a conventional oscillator, powered from
the 60 Hertz building power source. Thus, each pulse produced by
clock 17 and each increment of the counter 16 corresponds to 1/60
of a second. The system may be initialized by resetting counter 16,
to zero. A signal at terminal A, which may be generated manually,
through the use of a simple pushbutton switch, resets the counter
16. The counter then begins to increment in 1/60 of a second
intervals. Recalling that a day is comprised of 86,400 seconds, in
a system wherein each count in the counter represents a time
interval of 1/60 of a second, a 32 stage counter has a recycle
period greater than the two weeks, and a 48 stage counter has a
recycle period greater than 100,000 years.
The arrival time is set into counter 5 and applied to
transformation matrix 4 which simply interleaves the bits from
registers 5 and 6 in a manner determined by the wiring of the
matrix 4.
When the departure time feature is used, the scheduled departure
time of the guest is entered into register 7. The departure time is
a function of the check-in time. That is, the departure time is
merely the arithmetic sum of the check in time plus the duration of
the guest's stay. To enter the departure time into the system, the
duration of stay is entered into decimal keyborad 200, the output
of which is supplied to decimal to binary converter 202. The
duration of stay is preferably determined in hours, since guests
often do not check into a hotel at the beginning of the hotel's
day, usually beginning around noon and ending the following noon.
Binary register 208 stores a count corresponding to an hour in
system time. In the system under discussion, register 208 stores
the binary equivalent to 60 .times.to 360 = 21,600 which
corresponds to the number of counts in a one hour period. The
contents of register 208 are multiplied by the output from decimal
to binary converter 202 to generate a binary number equivalent to
the duration of stay in system time. This number is added to the
arrival time from counter 16 in adder 206 and stored in departure
time register 7.
The contents of register 7 together with the contents of registers
5 and 6, are applied to transformation matrix 4 through the
register 8 whereby they are interleaved. Further encipherment is
accomplished by adding the output of transformation matrix 4 with
the randomly generated key code in register 2 in a modulo 2 adder
3. The output of the adder 3, together with the contents of the key
code register 2 are applied to a further transformation matrix 20
to further scramble the codes. The output of the matrix 20 is
supplied to the input of a conventional psuedorandom sequence
generator 21. The output of the adder 3 is also supplied directly
to counter 13 to preset this counter.
When counter 13 is loaded, a signal B, which may be manually
generated using a push button switch, or automatically generated in
response to the loading of counter 13, enables coincidence gate 23.
Gate 14, coupled to the output of counter 13, provides a logic 1
when the counter has reached its full count. Thus, when counter 13
is preset from the output of adder 3, with a count other than a
full count, the output of gate 14 is a logic 0, which is inverted
to a logic 1, by operation of inverter 26, to enable gate 24. When
gates 23 and 24 are enabled, clock pulses from clock 22
simultaneously increment counter 13 and register 18 of the
psuedorandom sequence generator 21. Incrementing continues until
counter 13 reaches its full count, at which time the output of gate
14 assumes a logic 1 thereby disabling gate 24 through the
operation of inverter 26. In this manner, the key code, and the
output of adder 3 are further enciphered increasing still further
the security of the system. This encipherment prevents an
individual from isolating the arrival time from the codes imprinted
on the room key and subsequently counterfeiting a room key
including thereon an order code corresponding to the time at which
he seeks to enter the room illegally.
The output of the psuedorandom sequence generator 21, together with
the output of adder 3 is further enciphered in transformation
matrix 25 and applied to a key writer 27, which imprints, as
illustrated in FIG. 2, an encipherment 300 of the key code, room
number, order code and departure time on the key. In addition, the
room number 302, in decimal form, may also be imprinted on the key.
As illustrated in FIG. 2, the key may take the form of a key card
having a configuration equivalent to that of an ordinary credit
card.
Alternatively to entering the encipherment 300 as an array of holes
as shown in FIG. 2, the encipherment may be a printed or magnetized
array of marks, or any kind of signal in any form representing the
information in the encipherment.
In addition to the above information, the key card may also have
imprinted thereon hotel advertising 304.
The lock mechanism at each room will now be described. Referring to
FIG. 3, each lock mechanism is provided with an electronic key
reader 37, such as that described in U.S. Pat. No. 3,688,269. The
reader 37 reads the encipherment of the key code, room number,
order code and time of departure, from the inserted key card 28.
This encipherment is partially unscrambled by transformation matrix
38, which is the reverse of transformation matrix 25. The output of
transformation matrix 38 therefore corresponds to the output of the
adder 3 and the output of the psuedorandom sequence generator 21
after gate 24 has been disabled. The information on bus 32
corresponds to the output of adder 3 which was previously supplied
as the preset input to counter 13. At the remote lock mechanism,
this preset count is applied to register 43. The remaining bits
from transformation matrix 38 are applied to the shift register 31
forming part of psuedorandom sequence generator 39. When register
31 is loaded, clock 40 increments shift register 31 backwards,
while decrementing binary counter 45 previously preset to its full
count. Decrementing of register 31 and counter 45 continues until
comparator 44 detects correspondence between the preset count in
register 43 and the count in counter 45. At this point, the output
of comparator 44 goes to a logic 1, which, through the operation of
inverter 60, disables coincidence gate 41 to thereby block further
clock pulses from entering register 31 and counter 45. Register 31
now stores a binary number identical to that which was supplied
from transformation matrix 20 to shift register 18 of the
psuedorandom sequence generator 21 at the control console.
Transformation matrix 46, which receives the contents of shift
register 31 is the reverse of the transformation matrix 20. Thus,
the bits on bus 35 correspond to the guest key code, while those on
bus 33 correspond to the output of adder 3. The bits on bus 33 are
applied to modulo-2 subtractor 48, while the key code on bus 35 is
applied to the subtrahend input of the subtractor 48. The output of
the subtractor thus corresponds to the input to adder 3 from the
transformation matrix at the control console. Transformation matrix
49 is the reverse of transformation matrix 4 and thus, the output
of transformation matrix 49 corresponds to the order code, room
number and time of departure. The order code is supplied to
subtractor 50, the room number to comparator 51 and the time of
departure to the comparator 52 and subtractor 90.
Each lock mechanism is provided with a binary counter 65 operating
in synchronism with the binary counter 16 of the control console.
Clock 66 corresponds to clock 17, and thus when clock 17 provides
clock pulses spaced at 1/60 of a second, clock 66 also provides
pulses at 1/60 of a second intervals. Any lack of synchronism is
acceptable to the system as long as the time interval is within the
allowable time interval between check-in time and the time of
presentation of the key card 28 to the lock mechanism.
The count in binary counter 65 is applied to the subtrahend input
of the subtractor 50, while the minuend input receives the order
code from the transformation matrix 49. The output of the
subtractor 50 is supplied to a conventional threshold detector 68,
the threshold of which is set to correspond to the allowable time
interval between check-in time and the time of presentation of the
key card 28 to the lock mechanism. If the key card 28 is presented
to the key reader 37 within the predetermined time interval, the
output of the threshold gate 68 is at a logic 0, enabling the
coincidence gate 53, through inverter 67. The second input to gate
53 is coupled to the output of comparator 51 which compares the
room number derived from the transformation matrix 49 with the room
number stored in register 72. If a match exists, the output of
comparator 51 goes to a logic 1 causing the output of coincidence
gate 53 to also obtain a logic 1 enabling coincidence gate 69,
while simultaneously resetting shift register 54. Shift register 54
is now ready to receive a new key code. This new key code is
provided by the key code on bus 35, which is applied to the shift
register 54 through enabled coincidence gate 69 and OR gate 71. In
addition, the logic 1 at the output of gate 53 is applied to the
lock bolt control circuit 62 through the OR gate 55 to cause the
lock bolt associated with the room to move to its unlocked
position. The lock bolt control circuit may correspond to that
described in co-pending patent application Ser. No. 84,08, by
Stephen Paull and Paul A. Crafton, filed Oct. 26, 1970 and assigned
to an affiliate of the assignee of the present invention.
The guest continues to gain access to his room even after the
preset time interval determined by the threshold of threshold gate
68 has passed. Once the lock mechanism has been set with the new
key code, each time the guest presents his key card 28 to the key
reader 37, the encipherment is read therefrom and passed through
transformation matrix 38, psuedorandom sequence generator 39 and
the transformation matrix 46 to recover the key code and place it
on bus 35 in the manner just described.
More specifically, the bits on bus 32 correspond to the preset
count applied to the binary counter 13 of FIG. 1, while the code
applied to the shift register 31 from the matrix 38 corresponds to
the output from the shift register 18 of the psuedorandom sequence
generator 21 when coincidence gate 24 has been disabled. Clock 40,
operating through coincidence gate 41, shifts register 31 backwards
while decrementing counter 45, which has been preset to its full
count. When the preset count in register 43 corresponds to the
count in counter 45, the output of comparator 44 goes to a logic
high disabling gate 41. At this time, the output from shift
register 31, which is applied to the transformation matrix 46
corresponds to the guest key code and the output of the adder 3
after it has been interleaved by matrix 20. Transformation matrix
46 is the inverse of transformation matrix 20 and thus, the key
code is recovered on bus 35 and applied to comparator 47. Since the
key code on the guest's key card 28 now corresponds to the key code
stored in shift register 54, the output of comparator 47 goes to a
logic 1 generating an unlock trigger signal which is applied to the
lock bolt mechanism 62 causing the lock bolt of the room to move to
its unlocked position.
The time of departure feature will now be described. The guest's
time of departure has been recovered as previously explained and
applied to comparator 52 and subtractor 90. The comparator 52 also
receives the count in binary counter 65. When the count in the
binary counter 65 corresponds to the count representing the time of
departure, the output of the comparator 52 raises to a logic 1,
setting latch 96 to enable gate 94. The purpose of subtractor 90 is
to provide the guest with a check-out grace period. While the
subtrahend input of subtractor 90 receives the departure time, the
minuend input receives the count in counter 65. The difference
signal is applied to threshold circuit 92 having a threshold level
corresponding to the grace period. As long as the input to
threshold circuit 92 from subtractor 90 is below the threshold, and
thus within the grace period, the output of circuit 92 is at a
logic 0. When the grace period has lapsed, the output of threshold
circuit 92 assumes a logic 1 causing the output of coincidence gate
94 to assume a logic 1, enabling coincidence gate 70, while
resetting register 54. Each lock mechanism has associated therewith
a random number generator 73 and a shift register 74 storing the
random number generated by the generator 73. When coincidence gate
70 is enabled, the number stored in shift register 74 passes
through the gate 70 and OR gate 71 to the shift register 54.
Subsequent presentation of the guest key card 28 to the key reader
37 of the lock mechanism does not result in a logic high from
comparator 47 since the key code on the guest key card differs from
the key code now stored in shift register 54. Therefore, lock bolt
mechanism 62 is not triggered.
Provision is also made for allowing hotel employees to enter rooms
with a pass key. Pass keys are prepared in the same manner as the
guest's key cards. At each room, the entire circuitry illustrated
in FIG. 3, except for binary counter 65 and clock 66, are
duplicated. The room register associated with the pass key
circuitry at each lock mechanism, contains a common arbitrary room
number. The grace period determined by the threshold circuit 68 in
the pass key portion of the lock mechanism is set equal to the
length of the work shift and the time of departure is set to
correspond to the end of the work shift. In this manner, an
employee's key card is valid only for the duration of his work
shift.
FIG. 4 is a block diagram representation of the application of the
present invention to a hotel. Central console 500 may be connected
by means of wires to the hotel's restaurant 502, bar 503, shops 504
and the parking lot gate 505. Returning to FIG. 1, it can be seen
that the encipherment imprinted on the guest key card 28 is also
inserted into a central computer memory 400. This memory is
accessed by a card reading terminal 406 at each service area in the
hotel such as the bar or restaurant, using conventional computer
techniques. If the guest key card is still valid, the comparator
404 displays an accept signal at a signaling means 402 at the
service areas a reject signal otherwise.
By generating a random guest key code plus the room number, at the
cashier's console 408, the cashier can change at random the guest
key code in the central computer memory 400, thereby preventing the
guest from continuing to charge services after he has paid his
bill.
If a family or a group of persons is registered and assigned to two
or more rooms as a group, the rooms may be master keyed by storing
the key code used for the first key (as for example in a shift
register) and using the stored key code instead of a new key code
to generate the encipherment for the other room (s) of the group of
assigned rooms. Each key of the group of keys would be used in the
correct room lock mechanism the very first time the key is
inserted, but after the first insertion all keys may be used
interchangeably with each other. If it is desired to permit each
key to be used for any room of the group even the first time used,
the room numbers of all assigned rooms would be included in the
encipherment on each key, and the lock mechanism would accept that
one of the room numbers extracted from the encipherment that
corresponds to its own room number. The output of transformation
matrix 49 would involve all the assigned room numbers and would be
compared in turn with the binary register 72. If one compares
favorably, the output of comparator 51 becomes high.
As previously indicated, the system has application to baggage
lockers. When so used, the time of departure feature would
generally be omitted. Further, the inventive system has
applicability to the field of rental vehicles. The automobile
ignition lock, for example, may include a lock bolt mechanism and
control circuit such as the circuit 62 used in hotels. The
circuitry of FIG. 3 would be included in a box mounted in the
vehicle, while circuitry of FIG. 1 would be included in the rental
office.
While the invention has been particularly shown and described with
reference to a preferred embodiment thereof, it will be understood
by those skilled in the art that various changes in form and
details may be made therein without departing from the spirit and
scope of the invention.
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