U.S. patent number RE29,259 [Application Number 05/700,554] was granted by the patent office on 1977-06-07 for self re-keying security device.
Invention is credited to Daniel M. Sabsay.
United States Patent |
RE29,259 |
Sabsay |
June 7, 1977 |
Self re-keying security device
Abstract
A security system for use in secure areas, buildings, hotels,
automobiles and so forth. Each lock mechanism is controlled by a
decoding circuit having a changeable binary memory. A basic key has
two decodable information fields: a key field and an authorization
field. When a key field is sensed by the decoding circuit and found
to contain a number equal to the combination previously stored in
the decoding circuit memory, the lock mechanism is opened. If the
comparison does not find a match, the authorization field number
and the combination are then compared. If they are found to be
equal, the decoding circuit memory changes itself to the number
found in the key field and the lock mechanism opened. In this way,
lock combinations may be changed. In addition, the key may contain
other information fields, such as various levels of master
combinations, key insertion information, and so forth.
Inventors: |
Sabsay; Daniel M. (Cambridge,
MA) |
Family
ID: |
23380358 |
Appl.
No.: |
05/700,554 |
Filed: |
June 28, 1965 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
351298 |
Apr 16, 1973 |
03821704 |
Jun 28, 1974 |
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Current U.S.
Class: |
235/382.5;
713/185; 340/5.67; 340/5.24; 340/544 |
Current CPC
Class: |
G07C
9/215 (20200101) |
Current International
Class: |
G07C
9/00 (20060101); H04Q 003/00 () |
Field of
Search: |
;340/149A,149R,274C
;317/134 ;235/61.7B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pitts; Harold
Parent Case Text
This is a continuation of application Ser. No. 234,157, filed Mar.
13, 1972 now abandoned.
Claims
I claim:
1. The method of operating security device, comprising the steps
of
entering into said security device a key number and an
authorization number,
comparing the key number with a combination number previously
stored in said security device,
operating said security device, if the compared numbers are found
to match,
comparing the authorization number with the combination number
previously stored in said security device, if the key number was
found not to match the combination number,
causing the key number to be stored in said security device in
place of the previously stored combination number, if the
authorization number was found to match the combination number,
and,
operating said security device, if the authorization number was
found to match the combination number.
2. The method of claim 1, wherein said step of operating the
security device if the authorization number was found to match the
combination number comprises the steps of comparing the entered key
number with the number stored in place of the previously stored
combination number and operating said security device if the
numbers are found to match.
3. The method of claim 1, wherein said entering step further
includes the step of entering two combination identification
numbers, each of said combination identification numbers associated
with one of said key or authorization numbers.
4. The method of claim 3,
further comprising the step of first storing a plurality of
combination numbers of said security device, and,
wherein said step of comparing the key number with a combination
number previously stored includes the step of selecting the
combination number to be compared from the plurality of such
numbers on the basis of the combination identification number
associated with said key number.
5. The method of claim 3,
further comprising the step of first storing a plurality of
combination numbers in said security device, and,
wherein said step of comparing the authorization number with the
combination number previously stored in said security device
includes the step of selecting the combination number to be
compared from the plurality of such numbers on the basis of the
combination identification number associated with said
authorization number.
6. The method of claim 1, wherein said step of entering comprises
the step of decoding said numbers from information encoded on a
user's key.
7. The method of operating an .[.electrically.]. controlled
security device, comprising the steps of
retrievably storing a plurality of combination numbers in said
security device,
decoding from information encoded on a user's key a key number and
an associated first combination identification number and an
authorization number and an associated second combination
identification number,
comparing the key number with a particular one of said combination
numbers determined by said first combination identification
number,
operating said security device, if the compared numbers are found
to match,
comparing the authorization number with a particular one of said
combination numbers determined by said second combination
identification number, if the compared key number and combination
number were found not to match,
causing the key number to be stored in said security device in
place of the combination number selected by said first combination
identification number, if the compared authorization number and
combination number were found to match, and,
operating said security device, if the compared authorization
number and combination number were found to match.
8. The method of claim 7, wherein said step of operating said
security device if the compared authorization number and
combination number were found to match, comprises the steps of
comparing the key number with the number stored in place of the
combination number selected by said first combination
identification number and operating said security device if the
numbers are found to match.
9. The method of operating an .[.electrically.]. controlled
security system comprised of a plurality of security devices,
comprising the steps of
storing a plurality of combination numbers in each of said security
devices,
decoding from a user's key a key number and associated first
combination identification number and an authorization number and
associated second combination identification number,
comparing the key number with the one of said stored combination
numbers selected by said first combination identification
number,
operating one of said security devices, if the numbers are found to
match,
comparing the authorization number with the one of said stored
combination numbers selected by said second combination
identification number, if the key number was found not to match the
selected combination number,
causing the key number to be stored in said security device in
place of the one of said stored combination numbers selected by
said first combination identification number, if the authorization
number was found to match the selected combination number, and,
operating said security device, if the authorization number was
found to match the selected combination number.
10. The method of claim 9, wherein said step of operating said
security device if the authorization number was found to match the
selected combination number includes the steps of comparing the key
number decoded from the user's key with the number stored in the
location of the combination number selected by said first
combination identification number and then operating said security
device.
11. In a security device for .[.electrically.]. controlling a lock,
said security device having stored therein at least one combination
number.Iadd., .Iaddend..[.for operating said device,.].
.Iadd.comprising: .Iaddend.
means for entering a key number and an authorization number into
said security device,
means for comparing said key number with .[.one of.]. said
.[.stored.]. combination .[.numbers.]. .Iadd.number and for
comparing said authorization number with said combination number if
said key number is found not to match said combination number,
.Iaddend.
means for operating said security device if said key number is
found to match said combination number .Iadd.and for operating said
security device if said authorization number is found to match said
combination number and said key number is found not to match said
combination number, and .Iaddend.
.[.means for comparing said authorization number with said
combination, if the key number is found not to match said
combination number,.].
means for storing the key number in said security device in place
of said combination number, if the authorization number .[.was.].
.Iadd.is .Iaddend.found to match said combination number.[.,
and,.].
.[.means for operating said security device if the authorization
number was found to match said combination number.]..
12. The combination of claim 11, wherein said security device
comprises means for retrievably storing a plurality of combination
.[.number.]. .Iadd.numbers.Iaddend., and,
said entering means comprises means for entering a first
combination identification number associated with said key number
and a second combination identification number associated with said
authorization number.
13. The combination of claim 12, wherein said means for comparing
said key number with one of said combination numbers .Iadd.and for
comparing said authorization number with said combination number if
said key number is found not to match said combination number
.Iaddend.includes means for selecting for said comparison a
particular one of said plurality of combination numbers as
determined by said first combination identification number.
14. The combination of claim 12, wherein said means .Iadd.for
comparing said key number with said combination number and
.Iaddend.for comparing said authorization number with one of said
combination numbers .Iadd.if said key number is found not to match
said combination number .Iaddend.includes means for selecting for
said comparison a particular one of said plurality of combination
numbers are determined by said second combination identification
number.
15. The combination of claim 11, wherein said key number storing
means retrievably stores said key number in the location of the
combination number determined by said first combination
identification number.
16. The combination of claim 11, wherein said means for operating
said security device .Iadd.if said key number is found to match
said combination number and for operating said security device
.Iaddend.if the authorization number .[.was.]. .Iadd.is
.Iaddend.found to match said combination number .Iadd.and said key
number is found not to match said combination number
.Iaddend.comprises means for comparing the key number with the
number stored in place of the previously compared combination
number and then operating said security if the numbers match.
17. The method of operating an .[.electrically.]. controlled
security system comprised of a plurality of security devices, each
of said devices operable by entry of an assigned key number,
comprising the steps of
storing at least one combination number in each of said security
devices,
controlling a computer to retrieve from its memory the combination
number previously stored in a designated one of said security
devices,
controlling said computer to obtain a .[.randomly valued.].
.Iadd.selected .Iaddend.number and store said number in the memory
in place of the retrieved number,
producing a key encoded with said retrieved combination number as
an authorization number and said .[.randomly valued.].
.Iadd.selected .Iaddend.number as a key number,
decoding from the key said key number and said authorization number
and entering said numbers into said designated security device,
comparing said key number with said previously stored combination
number,
operating said designated security device, if the numbers are found
to match,
comparing the authorization number with the combination number
previously stored in the security device, if the key number was
found not to match the combination number,
causing the key number to be stored in said designated security
device in place of the previously stored combination number, if the
authorization number was found to match the combination number,
and,
operating said designated security device, if the authorization
number was found to match the combination number.
18. The method of operating a security device comprising the steps
of
storing a plurality of combination numbers in said security
device,
entering into said security device a key number, an authorization
number, and two combination identification numbers, each of said
combination identification numbers being associated with one of
said key or authorization numbers,
comparing said key number with one of said combination numbers
previously stored in said security device, selected on the basis of
the combination identification number associated with said key
number,
operating said security device, if the compared numbers are found
to match,
comparing said authorization number with one of said combination
numbers previously stored in said security device, selected on the
basis of the combination identification number associated with said
authorization number, if said key number was not found to match
said combination number,
causing said key number to be stored in said security device in
place of a previously stored combination number, said combination
number being replaced being selected on the basis of the
combination identification number associated with said key number,
if said authorization number was found to match the combination
number with which it was compared,
operating said security device, if the authorization number was
found to match the combination number with which it was
compared.
19. The method of operating a security device comprising the steps
of
retrievably storing a plurality of combination numbers in said
security device,
entering into said security device a key number, an authorization
number, and a combination identification number,
comparing the key number with a particular one of said combination
numbers determined by the combination identification number,
operating said security device, if the compared numbers are found
to match,
comparing the authorization number with said particular combination
number, if the key number was found not to match the selected
combination number,
causing the key number to be stored in said security device in
place of said previously stored particular combination number, if
the authorization number was found to match said particular
combination number, and,
operating said security device, if the authorization number was
found to match said particular combination number.
20. The method of operating a security device comprising the steps
of
retrievably storing a plurality of combination numbers in said
security device,
entering into said security device a key number and an
authorization number,
comparing the key number with all combination numbers previously
stored in said security device,
operating said security device, if any of the compared combination
numbers are found to match said key number,
comparing the authorization number with all combination numbers
previously stored in said security device, if no combination
numbers were found to match the key number,
causing the key number to be stored in said security device in
place of the previously stored combination number which matched the
authorization number if such a match occurred, and,
operating said security device, if the authorization number was
found to match any of the stored combination numbers.
21. The method of operating security device, comprising the steps
of
entering into said security device a key number and an
authorization number,
comparing the key number with a combination number previously
stored in said security device,
operating said security device, if the compared numbers are found
to match,
comparing the authorization number with the combination number
previously stored in said security device, if the key number was
found not to match the combination number,
causing the key number to be stored in said security device in
place of the previously stored combination number, if the
authorization number was found to match the combination number.
Description
BACKGROUND OF THE INVENTION
This invention relates to code responsive logic circuits for
operation of lock mechanisms.
There are many applications which require complex and changeable
lock systems. For example, in large hotels it is the current
practice to provide each room with a standard mechanical tumbler
lock. A guest is provided with a key which matches only the lock to
the room he is assigned. As keys are lost or taken inadvertently,
new keys must be made, which is a time consuming and costly
operation. Further, theft poses a very substantial problem. It is
often necessary to change or re-key door locks when it is suspected
that keys may have fallen into unauthorized hands.
A further complication in such a system is imposed by the usual
necessity of a number of levels of master keys. In a hotel, for
example, a maid must be provided with a master key which unlocks
rooms she services; for security reasons, however, it is generally
desirable to provide her with a master key which opens only the
rooms to which she is assigned and no others. A supervisor of maids
may be given a higher level master key which opens the rooms
assigned to all persons under her supervision. Still higher level
master keys may be given to hotel personnel, each for opening all
doors in a large section of the hotel in case of fire. Finally,
there may be a highest level master key which will open all
doors.
It may be seen, then, that the requirement of a number of levels of
master keys and the recurrent need to change individual door locks
or groups of door locks to control theft presents a very
substantial problem. Skilled locksmiths must be employed on a
virtually constant basis. Because of the cost and time involved in
changing locks, however, there is a resulting reluctance to make
such changes. As a consequence, security against unauthorized
entries and thefts is often lessened.
The problems encountered in the example given are found in any
present security system in which standard mechanical locks are
used. The application of the system and the types of master levels
involved may vary, but the problems remain.
A number of electrically controlled systems have been proposed to
meet some of the problems mentioned above. The simplest type uses a
decoding device mounted adjacent to each door lock which may be
pre-set. A binary combination number is set into each device by,
for example, simple switches. A user operates a push-button key
switch or inserts a card-type key on which a number is binarily
encoded. If a comparison between the entered key number and the
previously stored combination number finds the numbers equal, the
door is unlocked.
Such a system is an improvement over the mechanical lock systems
described above in that each door lock may be more easily changed
or re-keyed. However, to change a combination, each door lock must
be opened by security personnel as with a mechanical system.
Further, such systems have no provision for various levels of
master keys or combinations. Also, since most such systems protect
the re-keying switches with a mechanical lock, many of the above
problems remain.
Another type of electrically controlled system utilizes similar key
and decoding hardware, but transmits entered key combinations to a
central location where they may be checked by a computer. If the
entered combination is a proper one, the lock is opened under
computer control.
A further type similar to the centrally controlled system described
above controls a change in a door combination when a new key is
issued. In this system, the new combination is transmitted to a
door lock memory device as the key is produced.
The disadvantage to the centrally controlled type of system is that
the control device must be connected by cables to each lock. While
this is reasonable in a small system, its use in a large building
complex or in any application requiring a greater number of
controlled locks is very expensive. Also, in both large and small
installations, connecting cables are vulnerable to tampering.
Moreover, such a system cannot be used in any application where
direct connection with a controlled lock is impossible, as in a
fleet of vehicles. Further, as the numbers of controlled locks
grow, larger central computers and, in some instances, multiplexing
systems, are required which also greatly increases system
costs.
SUMMARY OF THE INVENTION
In the invention disclosed and claimed herein, each lock is
controlled by a decoding device which includes a resettable memory.
In its simplest form, the memory is preset with a multi-digit
combination. Each time a key is used, at least two numbers are
entered: a key number and an authorization number. If the key
number is found to match the combination previously stored in the
memory, the lock is opened. If they are found not to match, a
comparison is made between the entered authorization number and the
previously stored combination. If the comparison finds them equal,
the decoding device memory is reset to the entered key number, the
first comparison step is repeated and the lock is opened. In this
way, the lock is automatically re-keyed without the intervention of
skilled workmen. To change a lock combination automatically, all
that is necessary is to encode a newly issued key with a new key
number and also encode the last key number used.
The advantages of this invention may be easily seen by considering
its application to the hotel example described above. When a guest
registers for a room, he is given one or more key cards having at
least two fields of information encoded thereon. One field, the key
field, contains his new key number. The second, the authorization
field, contains the number assigned to the last guest to use the
room. Upon the first insertion of his key, the lock is
automatically re-keyed to his new combination number. Thereafter,
until the lock combination is changed, the only key number that
will open his door is that assigned to the present guest. No prior
guest keys will open the lock since the decoding circuit now
contains a new key number.
Because the lock combination is stored in a memory accessible only
by the logic circuit, the door locks may not be picked. Further,
each lock is re-keyed without the intervention of anyone but the
user. Finally, there is no interconnection of a central controller
with each lock mechanism, which saves a considerable amount of
installation cost and provides for use of these devices in mobile
vehicles and isolated locations.
Further, provision is made in this invention for multi-levels of
master keys. Each key encoded according to this invention contains
a total of four information fields. In addition to the two fields
discussed above, the key and authorization fields, two level number
fields are encoded, one associated with each of the key and
authorization fields.
Prior to the first use of the lock, the decoding circuit memory is
loaded with as many different combination numbers as there are
master levels. The level number associated with any particular key
number determines which of the previously stored combination
numbers the entered key number will be compared against.
Similarly, the level number associated with the entered
authorization number determines which of the previously stored
combination numbers the authorization will be compared against.
Accordingly, if the level numbers associated with the key and
authorization numbers are the same, which is the usual case, only
the combination number on the same master level as the entered
authorization number may be changed. In some instances, however, it
is desirable to "cross load" the decoding circuit memory. In such a
case, the entered authorization number may be utilized to change a
combination on a different level than that assigned to the
authorization number; the level number associated with the key
number determines the combination to be changed. When "cross
loading" is not desired, the key need only carry a single level
number.
In a variation where level number fields are not present on the
key, the lock may search its memory for the combination which
matches. This provides for a situation where several locks are
owned by different people but it is required that a single key open
them all. Because each lock owner will allocate the memory's
combination levels in his lock according to his own needs, the key
used in common among these owners might need to activate the
several locks by means of a combination stored in a different level
in each lock.
Lastly, the invention provides for a field on the key which will
cause the lock to suppress the latch opening function during the
operation cycle which re-keys a level. This is useful when a master
key is being changed; a visit to each lock will cause the lock to
adapt to the new master key but the occupants of the room will not
be disturbed. Subsequent use of this key in the adapted locks opens
the door normally.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates one form of a Sabsay key, the key utilized to
operate lock mechanisms of this invention in its preferred
embodiment.
FIG. 2 is an illustrative diagram showing a key and key reader
which operate a latch mechanism through memory and decoding
circuits.
FIG. 3 is a block diagram of the system that prepares the keys of
this invention.
FIG. 4 is a block diagram of the invention, illustrating the memory
and comparator devices.
FIGS. 5 to 8 are logic circuits disclosing the operation of the
coded shift register of FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a key 100 for use with this invention is
shown. In the preferred embodiment, the key 100 is made from
plastic, of a type and size that may be easily carried and handled.
In addition to the encoded information, key 100 may contain such
matter as printing or pictorial data for use, for example, as
advertising. Information may be encoded on card 100 in a variety of
ways, such as magnetic spots or colored ink. In the preferred
embodiment, information is encoded via punched holes or apertures
101.
The key 100 is comprised of three areas 103, 104, 105. The center
area 103 contains two data tracks, a "1's" track 107 and a "0's"
track 108. Together, the two data tracks contain four binary
numbers, as will be discussed below. A single bit in the binary
numbers is represented by a perforation in either one of the two
tracks with no perforation in the other track. For example, a
binary one is represented by a perforation in the "1's" track and
no perforation in the opposite position of the "0's" track. A
binary zero is represented by the opposite condition.
The coding areas 104 at the opposite ends of key 100 will always
contain a perforation 110 in line with the "1's" track. The purpose
of the perforations in the end areas 104 is to define the "1's"
track so that the key may be read from either end. Similarly, areas
105 contain a perforation 111, for the purpose of defining the
beginning end of the binary number. In this way, the key 100 may be
inserted into the reader with either side up. Thus, there is no
chance that a user can insert his key into a key reader the wrong
way.
The center coding area 103 contains, in the preferred embodiment,
four binary numbers: the key number and associated level number;
the authorization number and associated level number. The key
number is the binary number that will operate to open its
corresponding lock. The authorization number is the binary number
which will cause the key number to be loaded into the decoding
circuit member, replacing the combination number previously found
there. Level numbers determine the master level of both their
associated key and authorization numbers. The significance and use
of each of these numbers is best understood by reference to FIG. 2
and 3 and the above example of the use of this invention in a large
hotel.
As shown in FIG. 2, each door lock is provided with a key reader
114, a memory and decoding circuit 115 and an electrically
controlled lock 116. The key 100 is inserted by hand into reader
114. If it contains a key number matching the previously stored
combination, memory and decoding circuits 115 cause the lock 116 to
open.
In the preferred embodiment, four binary numbers, representing four
levels of key and authorization numbers, are stored in the memory
and decoding circuit 115. Keys to match at least one of the four
numbers are prepared under computer control as shown in FIG. 3. In
the hotel of the example, a check-in desk is provided with a
keyboard input-output device 120. When a guest checks in the hotel,
he is assigned a room, as in the usual course. The room number,
request for a new key and level number is entered via the
input-output device 120. The computer 121 receives the data and
retrieves from its memory 122 the key number previously assigned to
the last guest in the same room. The previous key number is
transmitted to a key producer 124 which encodes the previous key
number as the present authorization number along with the level
number entered by the desk clerk. A randomizer 126, a high rate
free-running counter, constantly generates changing binary numbers
of the desired number of digits and presents them to computer 121
via parallel lines 127. The computer 121 transmits one of the
random numbers, along with the selected level number, so the key
producer 124 where it is encoded in the new key as the key number.
To ensure uniqueness, the computer may check the random number
against key numbers currently in use. The new key contains, then, a
new key number selected completely at random, an authorization
number retrieved by the computer which is the prior key number
assigned to the same room and two level numbers entered by the
clerk. The position bits are encoded in each card by the key
producer. The newly prepared key is then presented to the
guest.
When the guest inserts his new key into the key reader 114 (FIG. 2)
located adjacent to his door lock, his new key number is first
compared by the memory and decoding circuits 115 with the
previously stored combination. The numbers do not match, so the
door is not unlocked. Then, the authorization number from his key
is compared to the previously stored combination. Since the
computer 121 caused the key producer to enter the previously stored
combination in the new key, a match is found. The memory and
decoding circuits then control the new random key number to be
entered into memory in place of the prior combination. The door is
then unlocked since the stored combination matches the key number
encoded on the guest's key. Thereafter, until a new key with a
different key number is created for that lock, the door will be
unlocked upon the first comparison since the key number encoded in
the key and the combination contained in the memory match.
Accordingly, by use of this invention, the door lock combination
may be changed each time a new guest is checked into a room. In
this way, no risk of theft because of previously stolen or retained
guest keys is encountered. Each guest may keep his key or discard
it, as he wishes. In a different application, a secure industrial
area, for example, new keys may be issued periodically or as
prudence dictates so as to regularly change the combinations of all
locks.
If a guest loses his key or wishes a duplicate, such keys may be
readily produced on the key producer 124. For a duplicate key, the
computer 121 is controlled to retrieve from its memory 122 the key
number assigned to the present guest and transmit the appropriate
numbers to the key producer. This may be controlled by appropriate
software with only the entry of the room number, level number and
duplicate key instruction into input-output device 120. A lost key
is replaced with a key containing a new random key number as
described above.
Referring still to the hotel example, a second master level of key
may be used by a maid. If, for example, one maid was assigned to
service ten rooms, the memory and decoding circuit would have
stored the same combination in the location assigned to the maid's
level. Her key, produced by the key producer 124, would remain
unchanged as long as it was desirable. If she were to terminate her
employment, for example, the ten rooms could be re-keyed at the
maid's level by production of a new key. As explained above, the
new key would be encoded with a new random key number and the prior
key number as its authorization number. Use of the new key in the
assigned locks would cause the re-keying of the ten rooms to the
new random key number.
Similarly, a higher level key could be produced which would unlock
all doors in a floor or wing of the hotel. The only difference
between such a key and those described above is that it would be
encoded as a different level key and would, thereby, access a
different stored combination.
In like fashion, a fourth level key could be produced which would
access yet a different previously stored combination to open every
door in the hotel. And, as may be readily appreciated, as many
levels of master keys could be employed as there are storage
locations in the memory and decoding circuit 115.
The computer 121 is, in the preferred embodiment, programmed in
obvious fashion to store in its memory 122 the present key numbers
of all levels of all locks. This information is necessary to enable
the locks to be re-keyed. When a new key number is selected from
the randomizer 126, it is also stored in the computer's memory 122
as the present key number of the assigned room. A printer 128 is
utilized to read out system administration information, as
desired.
In the above example, description of this invention was made in
terms of its application to a hotel with four levels of keys. As
may be readily appreciated, the number of levels may vary as needed
in the particular application. For example, use of the invention in
a high security defense plant may require many more than four
levels of keys. A change in the number of levels only requires a
change in the number of storage locations for different
combinations in the memory and decoding circuits.
The number of possible different combinations of key numbers
determines, of course, the density of information encoded on the
key as well as the number of bit storage locations required at each
level. Such numbers are, of course, variable and are set by the
requirements of the particular application.
The key reader 114 will take various forms dependent upon the type
of key encoding employed. In the preferred embodiment, which
utilizes a perforated key, the key reader is a standard
light-photocell arrangement.
Signals transmitted from the key reader to the memory and decoding
circuits 115, shown in detail in FIG. 4, may be in either parallel
or serial form. The four binary numbers are loaded into a coded
shift register 130 in the usual fashion. The key number from the
decoded key is transmitted to a comparator 131 and two identical
memory devices 132 and 134 over parallel lines 133.
The memory devices 132, 134 are standard units obtainable from the
usual suppliers of such items. In the preferred embodiment,
standard integrated circuit chips were used. Each is a read and
write memory, having as many word storage locations as there are
key levels. Each word storage location stores the number of bits
which make up the key or authorization numbers. Both memory devices
132, 134 contain the same stored binary numbers.
The level number associated with the key number is presented to the
word select (read) lines of memory device 132 and the word select
(write) lines of both memory devices 132, 134 over parallel lines
136. When the level number is received by memory device 132, it
serves as an address, causing the previously stored combination at
the designated level to be read out to the comparator 131 over
lines 138 after the memory device is enabled by line 141, as occurs
when the entire key has been entered.
If the comparator 131 finds a match between the key number on lines
133 and the previously stored combination on lines 138, the
comparator 131 turns on its output line 140. As will be explained
below, a "data ready" logic signal is derived which turns on line
141, indicating that the entire key has been entered. Coincidence
of the "on" state of the comparator output and the data ready
lines, determined by AND gate 142, triggers a high current driver
143. The driver 143, in turn, operates a latch mechanism 144,
causing the lock to be opened.
It may be seen, then, that if the key number read from the user's
key matches the previously stored combination, the latch mechanism
will be unlocked. A different sequence occurs, however, if the two
numbers do not match. In the instance when a lock's combination is
to be changed, as in the above example of a new hotel guest, the
new key number on lines 133 was chosen completely at random and
would not, therefore, match the prior combination. In such
instances, however, the prior key number is encoded on the new key
in a different location as the authorization number.
The decoded authorization number is transmitted to one side of
comparator 148 over parallel lines 149. Its associated level
number, which may or may not be the same level number appearing on
lines 136, is supplied to the word select (read) lines of memory
134 over lines 150. When the memory device is enabled by the data
ready line, the stored combination selected by the level number on
line 150 is read out to comparator 148 over lines 152. If there is
a match, the output line 154 of the comparator is turned on and
AND'ed with the data ready line by AND gate 155. Detection of the
coincidence turns on line 156 which is a write enable line to the
memory devices 132, 134. This causes the new key number on lines
133 to be entered in both memory devices at the locations
determined by the level number on lines 136.
Since the data ready line is still on, after the new key number is
entered in the memory device 132, it is outputed to comparator 131.
There, a match is found and the latch mechanism unlocked as
described above.
As is readily obvious, if a key is inserted in the wrong lock,
neither comparison step will find a match and the latch mechanism
will not be unlocked.
Two memory devices are disclosed in FIG. 4. Since each stores the
identical combinations, a single memory may be substituted, with
the appropriate timing logic, without departing from this
invention. Further, two comparators are shown which may, of course,
be replaced by a single comparator. Again, appropriate timing logic
would be required to present first the key number and then the
authorization number to a single comparator.
While it is believed that the coded shift register is readily
understandable from the above discussion of its operation in FIG.
4, a detailed diagram of its logic circuitry is disclosed in FIGS.
5 through 8.
Referring to FIG. 5, a bi-directional shift register 160 accepts
four logic signals and a data input derived from the decoded key.
The data input 161 is obtained by the logic circuit of FIG. 8 from
the two key data tracks. The shift left input on line 162 and shift
right input on line 163, derived by the logic of FIG. 7, determines
which end of the shift register will be loaded first. This, in
turn, is determined by which end of the key is first inserted into
the key reader. The clock input on the fourth input line 164 is on
each time a bit is sensed from either track of the key as it is
inserted into the key reader. The clock signal is derived by logic
of FIG. 8. The final input, a reset signal, is supplied on the
fifth input line 165. Its function is to clear the shift register
160 after the comparisons are made. As explained in connection with
the description of FIG. 4, the shift register 160 provides four
outputs, the new key number on lines 133, the key level number on
lines 136, the authorization number on lines 149 and the
authorization level number on lines 150.
As shown in FIG. 4, the shift register is referred to as "coded."
By this is meant that it is not necessary that all bit positions on
the key for a single binary number be in adjacent locations in the
shift register. For example, the new key number bits may be
interspersed on the key with authorization number bits. The
interspersal scheme is allowed for by the appropriate connection of
output lines to the shift register output points. Such interspersal
of number bits will aid the maintenance of security of the system
by greatly increasing the difficulty of unauthorized production of
keys.
The data ready signal line is turned on when the entire key has
been read, the shift register is loaded and a comparison is to be
made. In the preferred embodiment, the data ready signal, and other
internal logic signals, are derived by the logic circuit disclosed
in FIG. 6.
State 0 is defined as the reset state of the circuit. Accordingly,
state 0 lines 170, 171 are on before the key is first inserted into
the key reader. The output line 172 of AND gate 173 is off,
however, since no other inputs are present.
As will be explained in connection with FIG. 8, a clock pulse is
derived when each bit on a card is sensed. Accordingly, when the
key is first inserted, the first bit will cause clock line 174 of
FIG. 6 to turn on. AND gate 173 senses the coincidence between the
previously existing state 0 and the first clock pulse, and pulses
the counter 175 via OR gate 176 and counter input line 177. The
counter 175, in turn, triggers binary to decimal decoder 179,
causing the decoder to turn the state 0 line 170 off and the state
1 line 180 on.
AND gate 181 senses the coincidence of state 1 and the next clock
pulse, and again pulses the counter 175 through OR gate 176 and the
counter input line 177. The counter, in turn, causes binary to
decimal decoder 179 to turn the state 1 line 180 off and turn the
state 2 line 185 on. AND gate 188 has, then one input, the state 2
line 186, in an on condition. The second input, key-in, on line
187, indicates that the key has been fully read. Accordingly, the
circuit of FIG. 6 remains in state 2 during the rest of the key
insertion time. When the key-in line turns on, AND 188 gate pulses
the counter 175, which in turn causes the binary decoder 179 to
turn the state 2 line 185 off and turn on the data ready line 190.
The memory circuits are then enabled and the comparison read enable
lines steps begin. The circuit remains in this condition until it
is reset via reset line 191.
The logic of FIG. 7 determines whether the shift register 160 (FIG.
5) will load from the right or left side, depending upon which end
of the key is first inserted into the key reader. Flip flop 195 is
a standard J-K flip flop having one input grounded via line 196.
The second input is the AND'ed result of the signals on the data
line input 197 and the state 1 input line 198. If the data line
does not turn on during state 1 time, shift right line 200 is
turned on. If the data line turns on during state 1 time, the
coincidence is detected in AND gate 202 which causes the shift left
line 201 to be turned on, controlling the loading of the following
data through the left end of the shift register. As explained
above, the purpose of this is to allow insertion of either end of
the key in the key reader.
The data, clock, key-in and reset signals are derived, in the
preferred embodiment, by the logic of FIG. 8. Each key has, in the
preferred embodiment, two data tracks. As each data bit is received
on the track 1 line 205 or the track 2 line 206, multivibrator 207
is pulsed via OR gate 208 and line 209. A clock pulse on output
line 210 is, accordingly, produced during every sensed bit
time.
The two data track signals each are supplied as one input to two
AND gates 211, 212. The output of the two AND gates are OR'ed to
form the data signal. Which AND gate is enabled, to provide the
data signal, is determined by the first pulse sensed (110, FIG. 1)
which identifies the "1's" data track. This is, of course,
determined by the way the key is inserted into the key reader.
A flip flop 215 provides the controlling inputs to the two AND
gates via its true and complement output lines 216, 217. Which of
the AND gates is enabled is determined by the coincidence, or lack
thereof, of a bit signal on line 205 during state 0 time when state
0 line 221 is turned on. This coincidence is sensed by AND gate
240. If a bit is sensed during this time (from perforations 110),
line 216 is turned on and the bit signals on track 1 line 205
become the data signal. If no such coincidence is detected, line
217 remains on and the signals on track 2 line 206 become the data
signal. OR gate 241 receives the selected track signals to deliver
the data signals.
Each received data bit on either track is applied to retriggerable
monostable multivibrator 225 via OR gate 208 and line 209. AND gate
226 is turned on, generating a reset signal on line 227, when no
bits are received on either data line. The reset inverse signal is
developed therefrom in usual fashion.
NOR gate 230 generates an output on line 231 only when its three
inputs are off. A multivibrator 232 is turned on, supplying the
key-in signal, when NOR output line is turned on.
As may be readily appreciated by those skilled in the art, the
particular logic circuits may take many forms. This invention is
limited only by the following claims.
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