U.S. patent number 3,761,892 [Application Number 05/163,767] was granted by the patent office on 1973-09-25 for electronic locking system.
Invention is credited to Robert Joseph Bosnyak, John W. Chu.
United States Patent |
3,761,892 |
Bosnyak , et al. |
September 25, 1973 |
ELECTRONIC LOCKING SYSTEM
Abstract
An electronic locking system utilizes a circuit to compare
read-only-memories. Identical read-only-memories constitute a
portable "key" and a fixed "lock" which are instantaneously
compared electronically so that a determination of identity will
initiate a locking or unlocking operation.
Inventors: |
Bosnyak; Robert Joseph (Los
Gatos, CA), Chu; John W. (Sunnyvale, CA) |
Family
ID: |
22591470 |
Appl.
No.: |
05/163,767 |
Filed: |
July 19, 1971 |
Current U.S.
Class: |
235/382;
340/5.65 |
Current CPC
Class: |
G07F
7/0866 (20130101); G07C 9/00182 (20130101); G07C
2009/00761 (20130101) |
Current International
Class: |
G07F
7/08 (20060101); G07C 9/00 (20060101); H04g
003/00 () |
Field of
Search: |
;340/149A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pitts; Harold I.
Claims
We claim:
1. An n-dimensional logic function generation and comparison system
for use as an electronic locking system comprising,
An n-dimensional counter capable of generating in electrical
impulse form all numbers of a n-dimensional logic system;
A reference logic function source having a unique logic function
stored at a plurality discrete addresses therein, each of said
addresses having a one-to-one correspondence with a number in said
n-dimensional logic system, said reference logic function source
generating in electrical impulse form the logic function stored at
a specific address upon receipt in electrical impulse form of said
number corresponding to said address;
An unknown logic function source having a unique logic function
stored at a plurality of discrete addresses, each of said addresses
having a one-to-one correspondence with a number in said
n-dimensional logic system, said unknown logic function source
generating in electrical impulse form the logic function stored at
a specific address upon receipt in electrical impulse form of said
number corresponding to said address;
A comparator adapted to receive simultaneously said unique logic
functions in electrical impulse form from said reference logic
function source and said unknown logic function source, said
comparator comparing said simultaneously received logic functions
in stepwise progression, said comparator emitting a first
electrical signal if all logic functions match and emitting a
second and different electrical signal if at least one bit of one
pair of said logic functions does not match; and
An electrically responsive instrumentality adapted to be energized
or de-energized upon receipt of said first electrical signal.
2. The electronic locking system of claim 1 in combination with a
trial counter and alarm circuit to monitor the number of attempted
comparisons between the unknown logic function source and the
reference logic function source and to register an alarm when more
than a predetermined number of unsuccessful attempted comparisons
have been made and a maximum voltage sensor to deactivate the
locking system if a surge of current above a predetermined level is
surged through the system.
3. The electronic locking system of claim 2 wherein said unknown
logic function source is an m'th state to n'th state logic
encoder.
4. The electronic locking system of claim 3 wherein said m'th state
to nth state logic encoder is a decimal to binary encoder.
5. The electronic locking system of claim 2 wherein said
n-dimensional system is the binary system, said counter is an
oscillator driven binary counter and said reference and unknown
logic function sources are read-only-memories and said unknown
read-only-memory is detachably attachable with a socket having an
array of electrical connectors therein to establish temporary
electrical communication between the inputs of said unknown ROM and
said binary counter and between the outputs of said unknown ROM and
said binary comparator.
6. The electronic locking system of claim 5 wherein said
read-only-memories are MOS devices.
7. The electronic locking system of claim 5 wherein said
read-only-memories are fusible read-only-memories.
8. The electronic locking system of claim 5 wherein said
read-only-memories are amorphous semiconductor
read-only-memories.
9. The electronic locking system of claim 5 wherein said
read-only-memories are avalanche induced electromigration
read-only-memories.
10. The electronic locking system of claim 5 wherein said
electrically responsive instrumentality is a solenoid-operated lock
and wherein said first electrical signal from said comparator
serves to energize said solenoid to open said lock.
11. The electronic locking system of claim 10 in combination with a
recording means to record the time and place said unknown
read-only-memory is presented for comparison and to record the
identity of the authorized holder of the unknown
read-only-memory.
12. An n-dimensional logic function generation and comparison
system for use as a transient electronic locking system,
comprising:
An n-dimensional counter capable of generating in electrical
impulse form al numbers of an n-dimensional logic system;
At least one master reference logic function source having a unique
logic function stored at a plurality of discrete addresses therein,
each of said addresses having a one-to-one correspondence wtih a
number in said n-dimensional logic system, said reference logic
function source generating in electrical impulse form the logic
function stored at a specific address upon receipt in electrical
impulse form of said number corresponding to said address;
A tenant reference logic function source having a unique logic
function stored at a plurality of discrete addresses therein, each
of said addresses having a one-to-one correspondence with a number
in said n-dimensional logic system, said reference logic function
source generating in electrical impulse form the logic function
stored at a specific address upon receipt in electrical impulse
form of said number corresponding to said address;
An unknown logic function source having a unique logic function
stored at a plurality of discrete addresses, each of said addresses
having a one-to-one correspondence with a number in said
n-dimensional logic system, said unknown logic function source
generating in electrical impulse form the logic function stored at
a specific address upon receipt in electrical impulse form of said
number corresponding to said address, and said unknown logic
function source having an indicator means to indicate whether said
unknown source is an unknown tenant or a particular unknown master
logic function source;
A comparator adapted to receive simultaneously said unique logic
functions in electrical impulse form from the appropriate reference
logic function source and said unknown logic function source, said
comparator comparing said simultaneously received logic functions
in stepwise progression, said comparator emitting a first
electrical signal if all logic functions match and emitting a
second and different electrical signal if at least one bit of one
pair of said logic functions does not match; and
An electrically responsive instrumentatlity adapted to be energized
or de-enerigzed upon receipt of said first electrical signal.
13. The transient electronic locking system of claim 12 wherein
said n-dimensional system is the binary system, said reference and
unknown logic function sources are read-only-memories, wherein said
unknown read-only-memory is detachably attachable with a socket
having an array of electrical connectors therein to establish
temporary electrical communication between the inputs of said
unknown read-only-memory and said binary counter and between the
outputs of said unknown read-only-memory and said binary
comparator, wherein said electrically responsive instrumentality is
a solenoid-operated lock and wherein said first electrical signal
emitted by said comparator energizes said solenoid to open said
lock.
14. The transient electronic locking system of claim 13 in
combination with a trial counter to monitor the number of attempts
to compare said unknown logic function source with the appropriate
reference logic function source, an alarm circuit to register an
alarm and to deactivate said solenoid when more than a
predetermined number of unsuccessful comparison attempts have been
made, a maximum voltage sensor to deactivate said solenoid when a
surge of current above a predetermined level is passed through the
system, and a recording means to record the time and place said
unknown logic function source is presented for comparison and to
record the identity of the authorized holder of the unknown logic
function source.
15. The transient electronic locking system of claim 14 wherien
said read-only-memories are MOS devices.
16. The transient electronic locking system of claim 14 wherein
said read-only-memories are fusible read-only-memories.
17. The transient electronic locking system of claim 14 wherein
said read-only-memories are amorphous semiconductor
read-only-memories.
18. The transient electronic locking system of claim 14 wherein
said read-only-memories are avalanche induced electro-migration
read-only-memories.
Description
BACKGROUND OF THE INVENTION
This invention relates to an electronic n-dimensional logic
generation and comparision system for rapidly identifying an
unknown logic function source and, more particularly, relates to an
electronic logic generation and comparison system for use as an
electronic locking system.
Conventional mechanical locks and locking systems are by and large
based on the use of spring loaded pins and tumblers which control
the operation of bolt locks. Concentric cylindrical tumblers have a
series of pins passing through them so that inner tumblers can
revolve within outer tumblers only if the pins are lined up to a
depth at which they do not engage an adjacent tumbler. A key with a
series of varying indentations is inserted within the innermost
tumbler to line the pins up so the inner tumblers can revolve to
open the bolt lock. An inherent problem with mechanical
pin-and-tumbler locks is that an experienced locksmith can "pick"
them by lining the pins up one by one or a universal pick can be
used by an amateur to open any lock. Or, wax impressions can be
obtained of the key way and an appropriate bogus key can be
fabricated. Furthermore, once a lock is set it is costly and
difficult to reset them. And large locking systems have master key
and grandmaster keys which are capable of opening the locks,
thereby creating a greater number of pin settings which permit the
locks to open so the locks may be more readily picked.
It would be desirable, then, to utilize electrical or electronic
principles in implementing an electrical or electronic locking or
identification system. Attempts have been made to construct
electrically controlled locks. See for example U. S. Pat. No.
3,529,454 in which a solenoid-operated bolt lock is controlled by a
remote electromechanical code device. Such electromechanical
locking mechanisms require hardware components which take up
considerable space. Furthermore, the size of such remote control
devices varies in direct proportion to the complexity of the
potential code, so that extremely complex codes cannot be employed.
Furthermore, many of the devices require the user to be familiar
with the proper code to operate the control mechanism, a feature
which renders the systems less suitable for large scale transient
locking operations such as hotel door locks, industrial gate locks,
automobile locks, and the like.
Electronic switching and comparison circuits which are capable of
correlating the output from an unknown circuit with a reference
circuit are well-known. See, for example, Marcus, M. P., "Switching
Circuits for Engineers", 2nd ed. Comparison circuits which can
accommodate a rapid succession of time spaced electrical signals
are also known and have been widely used in data processing
applications. The development of integrated circuits has made it
possible to reduce the size of these circuits. Integrated circuits
contain numerous components such as resistors, diodes, and
capacitors, and are fabricated by the deposition of successive
layers or by the selective diffusion of resistive materials,
conductive materials and dopants such as boron and phosphorus onto
semiconductor materials. Such circuits are nonvolatile so they do
not require continuous power to be supplied. The more complex the
circuit the lower the yield but once a circuit has been
successfully fabricated and tested it will perform with a high
reliability rating.
Up to the present no one has applied miniature switching circutiry
techniques directly to portable large scale locking and
identification systems. Such circuitry has been considered to be
not portable enough to be utilized in such applications.
Furthermore, the cost of such a system has been considered highly
prohibitive. In addition no one has proposed a suitable electronic
logic function generation and comparison circuit for such an
application.
It is accordingly an object of this invention to provide
electronically a logic function generation and comparison circuit
wherein logic functions of a high order complexity are generated by
a portable and lightweight source (i.e. a key) and are compared
nearly instantaneously with the logic functions generated by a
known logic function source (i.e. a lock) to permit rapid and
reliable identification of the unknown source so that an unlocking
or locking operation may be performed.
It is a further object of this invention to provide electronically
an n-dimensional logic function generation and comparison circuit
which has a nearly infinitesimal chance of mis-identifying an
unknown logic function source.
It is another object of this invention to provide a portable
electronic logic function generation source which is matable with a
fixed electronic logic function identification circuit and which is
capable of withstanding intermittent mechanical shocks up to 30,000
g's. without malfunctioning.
It is another object of this invention to provide a portable
electronic n-dimensional logic function generation and comparison
circuit wherein a plurality of master key logic function sources
can be employed in alternation with a tenant key logic function
source to complete a comparison circuit to activate a locking
system.
A further object of this invention is the provision of an
electronic push button combination locking system wherein an m'th
and n'th state logic encoder is used to generate a series of test
logic functions which are compared with a fixed logic function
source so that the presentation of the proper combination initiates
a locking or unlocking operation.
It is a still further object of this invention to provide
electronically a logic function generation and comparison system
which will trigger an alarm system if a given number of improper
logic function sources are presented for identification to the
locking system.
It is a final object of this invention to provide electronically a
logic function generation and comparison system which will require
resetting by presentation of the proper unknown logic function
source once a given number of logic function sources have been
presented for identification and an alarm system has been
triggered.
SUMMARY OF THE INVENTION
An identical set of integrated circuit logic function sources such
as read-only-memories (hereinafter described as ROMs) is
fabricated. These logic function sources will be small in physical
size even though they both contain a large number of addresses each
of which is capable of storing a multi-bit word or byte of
information. One or more of the ROMs serve as a reference or lock
logic function source and the remaining ROMs serve as unknown or
key logic function sources.
The input leads of the reference ROM are connected to the output of
an n-dimensional counter and the output leads of the reference ROM
are connected to an n-dimensional comparator. This reference ROM
serves as a reference logic function generation source. As the
counter ranges through all number permutations possible in an
n-dimensional logic system with the given number of inputs for the
reference ROM and transmits these numbers in electrical impulse
form to the reference ROM a series of logic functions (in
n-dimensional logic) is produced by the reference ROM; there is a
one to one correspondence between each logic function generated and
each number transmitted to the reference ROM. The logic function
and their sequence is unique and depends upon the bytes stored at
the individual addresses of the reference ROM. The logic functions
are transmitted in electrical impulse form to the inputs of the
comparator.
An unknown portable ROM is carried by the individual or object
which seeks identification to activate the locking system. The
unknown ROM is inserted into a socket-like device which provides
electrical connections for the inputs and outputs of the unknown
ROM. The input leads to the socket are connected to the same
n-dimensional counter as the first ROM so that the numbers in
electrical impulse form are presented to the reference and unknown
ROMs simultaneously. The logic functions generated by the unknown
ROM are transmitted through the output connections of the socket to
the comparator. The logic functions generated by the reference and
unknown ROMs will then be compared by the n-dimensional comparator.
The comparator ascertains if they are identical in a stepwise
fashion, i.e. ascertains if each bit of each byte is identical. If
they are exactly identical the comparator will emit an electrical
signal which will activate an electrically responsive
instrumentality such as a solenoid operated lock. If they are not,
the comparator emits an electrical signal which can be used to
indicate a mismatch or can prevent the instrumentality from being
activated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating the components of the
electronic locking system of the present invention in combination
with a trial counter, and alarm network and maximum voltage
sensor.
FIG. 2 is a block diagram of the components included in a
master-tenant embodiment of the electronic locking system of the
present invention.
FIG. 3 is a side cross-sectional view of an unknown portable logic
function generation device.
FIG. 4 is a pictorial view of a portable logic function generation
device illustrating an external key-way nub.
FIG. 5 is a schematic circuit diagram of the basic logic function
generation and comparison circuit of this invention in combination
with a trial counter alarm system.
FIG. 6 is a block diagram illustrating the components of the
circuit of the present invention in combination with a key
recording system, a standby power supply, and a trial counter and
alarm network.
FIG. 7 is a schematic diagram of an embodiment of the present
invention employing an octal to binary state logic encoder for the
unknown logic function.
DESCRIPTION OF PREFERRED EMBODIMENT
Before describing the preferred embodiment in detail it is
instructive to set forth the mathematical and electronic precepts
on which it is grounded. An n-dimensional logic system is one in
which n discrete states are capable of combination in any manner
and sequence to form logic functions. For example, the decimal
system has ten discrete states, i.e. the numbers 0 through 9, which
can be used to generate a multitude of logic functions, e.g. sums,
or powers of the ten basic numbers. The binary system has two
discrete states, 0 and 1; the tertiary system has three discrete
states, 0, 1 and 2, and so on. Any of these logic systems, i.e. an
n-dimensional logic system, can be used to form logic
functions.
The discrete states of an n-dimensional logic system are typically
represented in electronic form as fixed voltage levels (although
theoretically they could be represented by fixed impedances,
currents or the like). The two states of the binary system are
often represented in electronic form as a more positive fixed
voltage for a 1 and a less positive voltage for 0 (so-called
positive logic) or a less positive voltage for a 1 and a more
positive voltage for 0 (so-called negative logic). A tertiary
system could be handled in electronic form, for example, by
assigning a zero voltage for 0, a positive fixed voltage for 1 and
a higher positive fixed voltage for 2. Throughout the following
description of the preferred and ancillary embodiments a binary
system is used for purposes of example only and it is to be
understood that any n-dimensional logic may be used with the
reference and unknown logic function sources. The invention is
premised on the application of miniature circuitry to prepare
exceedingly complex logic function sources for use as comparison
components in an electronic locking system and higher order logic
systems have higher inherent complexity.
Referring now to the block diagram of FIG. 1 it can be seen that
start switch 111 controls the energization of trial counter 105,
binary counter 107 and oscillator 108, and binary comparator 103.
The combination of oscillator 108 and binary counter 107 comprises
an address generation subcircuit 109 which can generate rapidly in
sequence all possible binary permutations for a given number of
inputs to a reference logic function source 102 and an unknown
logic function source 101. The binary numbers are generated in
electrical impulse form and may be generated by any binary counter,
e.g. TEXAS INSTRUMENTS 54/74160 or 54/74193, SIGNETICS 8284 or
8281, driven by an oscillator. Such subcircuits can generate well
in excess of 10.sup.8 numbers/seconds.
The binary coded electrical impulses received by the reference
logic function source 102 and the unknown logic function source 101
will cause the generation of respective logic functions which
consist of binary numbers in electrical impulse form and which are
then transmitted to parallel inputs of binary comparator 103.
Binary comparator 103 examines each of the binary bits of the
side-by-side functions to determine if they are identical. Such
binary comparators are built around well known logic circuitry. For
example, see Ryder, John D., "Electronic Fundamentals and
Applications," pp. 521, et. seq. Binary comparators currently
available on the market include: Fairchild model numbers 9324 and
93L24; Signetics model number 8242; and Texas Instruments model
numbers 5486, 7486, 54L86, and 74L86. Binary comparator 103 will
produce a first electrical signal if all inputs are identical. If
there is at least one mismatch between the logic functions received
then a second electrical impulse is emitted. The output of binary
comparator 103 can be keyed to a variety of electro-mechanical
instrumentalities 104 so that the instrumentality is energized or
de-energized only if the first electrical signal is received. As an
adjunct to the basic circuit of the present invention a trial
counter 105 receives an input from lead 110 by which it can monitor
the number of times that an unknown logic source is presented for
identification. The trial counter may be any electro-mechanical or
electronic counter, although the electronic counter circuit 117 of
FIG. 5 is the preferred embodiment. The trial counter may be
pre-set to trigger alarm 106 when a given number of improper
unknown logic function sources have been presented. Additionally,
the trial counter can be reset to zero by input 112 whenever
electro-mechanical instrumentality 104 is energized or
de-energized. Any suitable alarm system 106 may be employed.
To implement the present invention it is necessary to utilize logic
function sources which are non-volatile and which are embodied in
miniature circuitry. To obtain this feature it is necessary that
the individual elements of the logic function circuits be at least
temporarily fixed or programmed to represent a series of unique
logic functions at specific addresses. It is also desirable that
the logic function sources may later be changed, i.e. reprogrammed,
so that the "lock" may be changed. These requirements are satisfied
by a number of read-only-memories including mask programmed
read-only-memories (ROMs), fusible ROMs or FROMs, MOS ROMs
fabricated with MOS technology, amorphous semiconductor ROMs and
avalanche induced electromigration ROMs.
Read-only-memories, commonly denoted ROMs, consist of a complex
interlayering of diodes and other components, i.e. fuses and
amorphous demiconductors, which are connected together to form an
array of specific addresses each of which is capable of inherently
storing a given number of bits or bytes of information. If a binary
logic system is employed, a bit of information, i.e. a 1/0 or a
0/1, is represented respectively by a functioning diode link or a
fused diode link (a diode which has been rendered inoperative by a
surge of electrical current so that an open circuit exists). Mask
programmed ROMs have a fixed arrangement of diodes and open
circuits and can never be reprogrammed. Fusible ROMs or FROMs have
an arrangement of diodes and fuses which can be altered by blowing
additional fuses by surges of current. This process is, however,
irreversible so that, eventually, the fusible ROM would approach
the situation where all diode links were fused. Some MOS ROMs may
be reprogrammed at will and are especially desirable for their low
power consumption characteristics. Amorphous semiconductor ROMs and
avalanche induced electromigration ROMs are also field
programmable.
ROMs are defined in terms of the input and output leads as 2.sup.M
.times. N where M is the number of input leads (determining the
binary input combinations) and N is the number of output leads
(determining the complexity of the logic functions produced). Such
ROMs as are currently available include: Mask programmed ROMs --
Signetics model numbers 8224 and 8228; fusible ROMs -- Harris
semiconductor model number HROM 0512 (64 by 8), HROM - 1256 (256 by
1); Monolithic Memories model numbers 6305 and 5305; Motorola model
number MC 10139, and Signetics model number 8223; MOS ROMS -- INTEL
model numbers 1601 and 1701; amorphous semiconductor ROMs --
Ovionics model number RM - 256; and avalanche induced
electromigration ROMs -- INTERSIL model number 5600C.
The preferred and ancillary embodiments of this invention may be
fabricated by incorporating the listed commercially available
integrated circuit components or a custom designed integrated
circuit incorporating the oscillator, binary counter, programmable
or fusible ROMs, binary comparator, trial counter and alarm may be
fabricated. The latter alternative is a more desirable approach for
successful large scale commercial or consumer applications. Whether
commercial components or a custom designed integrated circuit are
utilized the comparison circuit will have highly desirable
reliability and thermal shock characteristics and will be able to
withstand intermittent physical shocks up to 30,000 g's. See
Madland, et. al., "Integrated Circuit Technology," pp. 344-347. To
add greater reliability various portions of the comparison circuit
may be made redundant.
An advantage of the present invention is that astronomically large
numbers of unique logic functions can be generated in extremely
short periods of time. Logic functions containing 10.sup.8 bits of
information can be processed by the system of the present invention
in one second. Additionally, microcircuitry renders the present
invention applicable to countless commercial and consumer
situations. A list of the many possible applications includes
personnel identification, the opening of doors, the identification
of a person for purposes of advancing consumer credit, the
establishment of a permanent record of one's presence at a
particular place at a particular time, etc.
The circuit represented schematically in FIG. 5 is used to
illustrate, by way of example only, a particular application of the
system of the present invention. The output of binary counter 124
is transmitted to the inputs of a reference or lock ROM 122 and the
ROM socket 121. Since the number of address related output leads of
binary counter 124 is equal to the number of input leads to the
lock ROM 122 and the ROM socket 121, the binary counter will
present in electrical impulse form every binary combination
possible to lock ROM 122 and ROM socket 121 and thence to unknown
or key ROM 123 which is insertable within ROM socket 121.
The outputs from lock ROM 122 are connected to the input of binary
comparator 120. The equal number of outputs from ROM socket 121
(with key ROM 123 inserted therein) are also connected to the input
of binary comparator 120. Binary comparator 120 is programmed to
compare the respective values for the outputs of lock ROM 122 and
socket 121 to determine identity. If all binary bits of all logic
functions are identical a uniform voltage, representing the binary
number 1, is emitted from binary comparator 120.
In order to render the system crack proof it is necessary to
prevent someone from ascertaining the logic functions which are
stored at indivdual addresses. Since the addresses are externally
accessible through socket 121 an unauthorized person can present
all possible binary functions through the output pins of socket 121
and, if the system is designed to shut off at the first mismatch,
the unauthorized person will eventually ascertain the logic
functions at each address so long as he does not conduct successive
unsuccessful matching attempts in excess of the number which will
trigger the alarm. Thus, it is highly desirable that the system
will be rendered inoperative only after the complete sequence of
logic functions have been generated with the occurrence of one or
more mismatches.
The operation of the electronic locking system is initiated by
operating pushbutton 152. The energization of the set input of
flip-flop 136 causes the output Q, initially 0, to go from zero to
1. The change of the Q output of flip-flop 136 from 0 to 1
initiates a pair of pulses from the pulse generator 137. The Q
output of pulse generator 137 goes from 1 to 0 to 1 while the Q
output goes from 0 to 1 to 0. One shot pulse generators which are
available commercially include Fairchild model numbers 9601 and
9602, Signetics model number 8162 and Texas Instruments model
numbers 54121, 54122, and 54123. The Q pulse resets the individual
outputs a.sub.1, a.sub.2, . . . a.sub.n.sub.+1 of binary counter
124 to 0s. Once a.sub.n.sub.+1 goes to 0 the inhibition control of
oscillator 125 is lifted so that oscillator 125 begins to oscillate
and drive binary counter 124. Meanwhile, the Q pulse of pulse
generator 137 sets flip-flop 153 so that the output of the
flip-flop becomes 1. As oscillator 125 increments the outputs
a.sub.1, a.sub.2. . . a.sub.n from all 0s to all 1s the comparison
process described above takes place.
If there is a single mismatch between a single bit of a word at the
same address of the lock ROM and the key ROM the appropriate
Q.sub.i will go from 1 to 0 and the output of inverter 141 will go
from 0 to 1. The 1 output of inverter 141 will reset the flip-flop
153 so that its output will go from 1 to 0. As soon as a single
mismatch occurs the output of flip-flop 153 will go to 0 and will
remain at 0 for the duration of the complete cycle of operation. In
effect, flip-flop 154 remembers that a mismatch has occurred so
that the system does not have to be shut down before the complete
cycle has been run. If no mismatch has occurred during the complete
cycle the output Q of flip-flop 153 is one. Since the output of
NAND gate 143 is one unless both inputs are one in which case the
output is 0 solenoid 144 will only be activated when the cycle has
run (i.e. a.sub.n.sub.+1 becomes 1) and no mismatch has
occurred.
In order to prevent an unauthorized person from continuously
attempting to present logic functions for comparison, it is
desirable to use a trial counter and alarm system powered by a
separate power supply V.sub.cc2 which is always on to insure a
record of the number of trials in the event the comparison circuit
power supply is cut off. In the embodiment of FIG. 5 two toggle
flip-flops are used in conjunction with a NAND gate and a solenoid.
The truth table of the toggle flip-flop is shown below.
##SPC1##
Where: Q.sub.n is the state before the clock pulse, and
Q.sub.n.sub.+1 is the state after the clock pulse. When the output
of NAND gate 143 goes from 1 to 0, i.e. when the locking system is
energized or de-energized, trial counter 117 is reset by the
individual resetting of toggle flip-flops 132 and 133. When an
additional trial is attempted the output of flip-flop 136 goes from
0 to 1. Since the T input of flip-flop 132 is connected to a
separate trial counter power supply V.sub.cc2 through a resistor T
is always 1 so that the output Q of toggle flip-flop 132 goes from
0 to 1. When the output of flip-flop 135 arrives at toggle
flip-flop 132 the output of toggle flip-flop 132 was still 0.
Therefore, the output Q of toggle flip-flop 133 does not change
since its T input is 0; this will present inputs of 1, 0 to NAND
gate 127. If this trial fails the next trial will toggle both
toggle flip-flops 132 and 133 so the inputs to NAND gate 127 will
be 0, 1. If the third trial fails, the inputs of the NAND gate 127
will read 1,1. Thus, a 0 will result at NAND gate 127's output. The
trial counter will be held at 1, 1 through the set inputs to the
toggle flip-flops 132 and 133 which override the clock pulse. The 0
at the output of NAND gate 127 will activate solenoid 147 and turn
on an alarm system. The alarm will continue to operate until the
proper key is used to make the output of NAND gate 143 go to 0 so
that the reset inputs to toggle flip-flop 132 and 133 can override
the set inputs so that the alarm will be turned off.
The block diagram of FIG. 6 illustrates several additional features
which are added to the embodiment of the invention illustrated in
FIG. 1. A reserve power supply 119 such as a long life dry cell may
be added to the system to allow the system to operate in event of a
power failure. The circuitry included in the system of the present
invention requires little current so that only a small battery or
reserve power supply network is required. Also, a key recorder 118
has been added to work in conjunction with the key logic function
source. A fixed portion of the addresses in the key logic function
source or the overall pattern of the key logic function can be used
to indicate the identification of the key (and therefore the
identification of the authorized key holder) which can be recorded
in conjunction with the place at which the key was used
(information which can be obtained from the lock logic function
source) as well as the time and date. A maximum voltage sensor 121
serves as an additional safeguard in the event that a burglar
attempted to break down the system by forcing large currents
through it. If a surge of current were detected by the maximum
voltage sensor 121 the whole system would shut down, the alarm
would be triggered and the locking system could not be reactivated
until a person with the proper key arrived.
For large scale portable applications of the system of the present
invention it is necessary that a key logic function source be
fabricated in a form that is highly portable as well as secure from
mechanical shock. One embodiment using a portable ROM as a key is
illustrated in the cross-sectional view of FIG. 3. Pins 71 of
packaged integrated circuit ROM 70 are mounted on the straight
through pin socket 77, and the composite of 70 and 77 is then
affixed to the interior of cylindrical form 73. Cylindrical form 73
may also serve as an electromagnetic shield for the packaged
integrated circuit. Pin socket 77 is open at the bottom end so that
when key form 73 is inserted into a key channel, socket 77 will
make electrical contact with interlocking electrical contacts which
are in electrical communication with the identification circuit. A
sealant 72 protects ROM 70 from the corrosive effect of external
exposure and from mechanical shock. Access to ROM 70 is obtained by
removal of plug 76 which is attached to key handle 75 and by
removal of sealant 72.
FIG. 4 shows key-way nub 74 to be mounted externally on cylindrical
form 73. Nub 74 serves as a guide that will ride in a key-way
adjacent to the key channel. A key way with a particular
configuration and a particular pin-socket configuration add two
more threshold tests to the identification scheme of the present
invention. For example, the key-way may require the key to be
inserted and twisted so the electrical contacts within the key way
line up with the electrical connectors in ROM socket 77.
If the identification system of the present invention is applied to
a locking system a great advantage is obtained over conventional
locks or electro-mechanical locks in that a high degree of security
is achieved. A binary ROM with M inputs and N outputs (a 2.sup.M
.times. N ROM) has a probability of 1/2.sup.M.sup.+N that a
randomly programmed 2.sup.M .times. N ROM can match the logical
function stored at a given address and a probability of
1/(2.sup.N).sup.2 ) that each and every address will be matched.
Thus, for example, a ROM that has three inputs and four outputs has
1/c24).sup.2 = 1/(16).sup.8 .apprxeq. 10.sup.-.sup.10 probability
that a randomly programmed 2.sup.3 .times. 4 ROM will contain
identical information at each and every address. The degree of
security that is achieved by utilizing ROMs in a locking system
surpasses the security which is currently obtainable, especially
for commercial applications such as hotels or building locks.
When the electronic locking system of the present invention is
applied to large scale locking systems it is highly desirable to
include an override or bypass scheme so that a hotel or building
management can have master or grandmaster logic function sources to
trigger locks without having immediate access to all individual
logic function sources. This bypass may be accomplished, as
indicated in FIG. 2, by a switching means 166 which is activated by
the key 161. The switching means 166 serves to select the proper
reference logic function source 165, i.e. selects either master
reference ROM 163 or tenant reference ROM 164, for comprison with
the key ROM. The switching means may be an electro-mechanical relay
which is thrown by the presence or absence of an additional
connector pin on the key. Or the switching means may be electronic
and may be included as logic functions located at preliminary
addresses in the key which activate a multiplexing unit in the
stationary portion of the identification circuit. The multiplexing
unit will then permit comparisons to be made only between the
appropriate (master, grandmaster, etc.) reference logic function
source 165 and the key logic function source 161. If the unknown
logic function source is a tenant key 161 it will be compared with
the tenant reference logic function source 164 so the tenant keys
will operate as described above. With large scale applications it
is further desirable to be able to readily rotate or change locks
or to expand the system by adding additional or larger ROMs.
Miniature circuit logic function sources can be readily replaced or
rotated and additional or larger ROMs can be added. In fact new
matched pairs can be employed if a key logic function source is
lost. And, as described supra, the logic functions contained in
fusible ROMs can be altered by fusing further links while MOS
programmable ROMs can be reprogrammed at will.
For certain high security applications such as bank vaults and for
applications in which portable keys are inconvenient combination
locks are desirable. The use of an m'th to n'th state logic encoder
can serve as the unknown logic function source. For example, in
FIG. 7 an octal to binary encoder, shown as circuit 140 (obtainable
by using eight of the 10 input leads and three of the four output
leads of Harris Bipolar Keyboard Encoder HD-0165) is used to
generate the unknown logic function source. The presentation of the
right eight digit number (the approximate size of a phone number)
to the eight address, three bit word encoder results in a
probability of 1/2.sup.24 .apprxeq. 10 .sup.-.sup.8 that a random
number would open the lock. The encoder as well as the other
components of the circuit can be fabricated in an integrated
circuit so the largest component by far in physical size would be
an 8 digit push button panel for the encoder. And, for fire
security, the encoder and reference ROM can be located remote from
the vault.
In operation, reset button 90 is depressed to reset the output of
binary counter 91 to 0, 0, 0 and to set the output of flip-flop 92
to 1. The first number button is depressed thereby presenting the
first unknown logic function to binary comparator 93. The logic
function stored at the first address of the lock logic function
source is presented to binary comparator 93 simultaneously with the
first unknown logic function source. If a match occurs between all
corresponding bits of the two logic functions the output of NOR
gate 95 remains 0 so that the Q of flip-flop 92 remains 1. When the
first push button is released the binary counter is advanced to the
next number because the clock input goes from 0 to 1. The process
is repeated and when all logic functions have been compared (the
output of the binary counter is 1, 1, 1) and if all logic functions
match, the output of flip-flop 92 will remain 1 so the output of
NAND gate 97 will be 0 and solenoid 98 will be activated. Every
unsuccessful attempted comparison will be recorded by the
tabulation of eight address comparisons without a reset by trial
counter 99. If more than a preset number of unsuccessful attempted
comparisons occurs then an alarm 100 will be triggered via NAND
gate 101.
While a number of specific embodiments of the preent ikvention have
been set forth in this specification, they are intended to be
representative only and the scope of this application for Letters
Patent is intended to be limited only by the scope and spirit of
the appended claims.
* * * * *