U.S. patent number 3,587,051 [Application Number 04/884,440] was granted by the patent office on 1971-06-22 for electronic combination switching device.
This patent grant is currently assigned to North American Research Corporation. Invention is credited to John Morris Hovey.
United States Patent |
3,587,051 |
Hovey |
June 22, 1971 |
ELECTRONIC COMBINATION SWITCHING DEVICE
Abstract
An electronic combination switching device for storage safes,
credit card verification, etc. having a randomly varying
operational sequence such that unauthorized persons cannot
determine how to operate the device by observing an authorized
person operate it. A random bit word is loaded into a storage
register having preselected stages connected to a manually operable
decoder. The authorized user observes the condition of the various
register stages by indicator lights, and, having knowledge of the
preselected stages, or combination, actuates the decoder to produce
a raised output. Each proper actuation is accumulated in a counter
and a new random word is loaded into the register after each
actuation. The counter yields an output after a predetermined
number of proper actuations. Improper actuations reset the counter
and operate an alarm.
Inventors: |
Hovey; John Morris (Oxon Hill,
MD) |
Assignee: |
North American Research
Corporation (Oxon Hill, MD)
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Family
ID: |
25384635 |
Appl.
No.: |
04/884,440 |
Filed: |
December 11, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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791439 |
Jan 15, 1969 |
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Current U.S.
Class: |
340/5.27;
340/543; 361/172; 340/5.3; 340/5.54 |
Current CPC
Class: |
G07C
9/00698 (20130101) |
Current International
Class: |
G07C
9/00 (20060101); H04q 003/02 () |
Field of
Search: |
;340/147,164,167,274
;317/134 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yusko; Donald J.
Parent Case Text
This application is a continuation-in-part of application Ser. No.
791,439, filed Jan. 15, 1969 now abandoned.
Claims
What I claim is:
1. An electronic combination switching device comprising:
a. a plural stage register,
b. means for loading a random bit word into the register,
c. selective switching means coupled to preselected stages of the
register for producing an output upon proper manual actuation
dependent upon the condition of the register stages and knowledge
of the preselected stages, and
d. means responsive to the output from the selective switching
means for actuating the switching device.
2. An electronic combination switching device as defined in claim 1
wherein the means recited in subparagraph (d) comprises a counter
and decoding means therefor for yielding an output after a
predetermined number of successive counts.
3. An electronic combination switching device as defined in claim 1
further comprising means responsive to the actuation of the
selective switching means for loading a new random bit work into
the register.
4. An electronic combination switching device as defined in claim 2
further comprising means responsive to the actuation of the
selective switching means for loading a new random bit word into
the register.
5. An electronic combination switching device as defined in claim 2
further comprising means response to the improper actuation of the
selective switching means for resetting the counter and actuating
an alarm device.
6. An electronic combination switching device as defined in claim 1
further including means for indicating the condition of each
register stage.
7. An electronic combination switching device as defined in claim 1
further comprising:
a. a second plural stage register for loading with a random bit
word by the means recited in subparagraph (b) of claim 1,
b. second selective switching means coupled to preselected stages
of the second register,
c. means responsive to the proper actuation of the second selective
switching means for producing an output signal, and
d. means responsive to the means recited in subparagraph (d) of
claim 1 and subparagraph (c) above for producing a final output
signal.
8. An electronic combination switching device as defined in claim 1
wherein the selective switching means is individually coupled to
the preselected register stages by means comprising:
a. a card insert station having a card receiving slot and sensing
means disposed adjacent the slot, and
b. a card insertable in the slot and having electrical circuit
defining means thereon cooperable with the sensing means to effect
the desired circuit coupling.
9. An electronic combination switching device as defined in claim 1
wherein the selective switching means comprises:
a. a plurality of decoding means individually coupled to
preselected stages of the register, and
b. a plurality of switches individually coupled to the outputs of
the decoding means, whereby a particular decoding means may be
manually actuated by the closure of its associated switch
10. An electronic combination switching device as defined in claim
1 wherein the selective switching means comprises:
a. an AND gate, and
b. a plurality of single-pole double-throw switches individually
coupled between preselected stages of the register and the AND
gate.
11. An electronic combination switching device as defined in claim
10 further comprising means responsive to the improper actuation of
all of the switches for enabling the actuation of the switching
device and simultaneously actuating an alarm device.
Description
BACKGROUND OF THE INVENTION
This invention relates in general to a novel electronic combination
switching device, and more particularly to such a device having a
randomly varying or pseudo randomly varying operational sequence
which prevents unauthorized persons from breaking the combination
even after observing authorized persons operate the device. It has
special, although by no means exclusive, application to combination
locks for bank vaults, storage safes, etc., and to identification
or credit card verification.
The prior art electronic combination locks, as exemplified by U.S.
Pat. Nos. 3,024,452 --Leonard, 3,093,994 --Richard, and 3,234,516
--Miller, are generally operated by the selection or closure of a
predetermined sequence of switches, which sequence constitutes the
combination. In all cases, however, the sequence, once set, is
fixed and invariant, and thus anyone can operate the device by
merely observing an authorized person operate it and then repeating
the latter's procedure. This lack of variance in operational
sequence has long constituted a serious drawback in the prior art
devices, and has become more a cut in recent years in view of the
development of very sensitive and sophisticated electronic
surveillance equipment which enables undetected observations of,
for example, a band vault lock during operation.
Combination switching devices have been embodied in I.D. or credit
card verifiers, as exemplified by U.S. Pat. No. 3,317,799 --Kellen,
in which the bearer inserts the card, carrying coded electronic
indicia of the combination, into a sensing station in the verifier.
He thereafter depresses the correct combination of switch buttons
corresponding to the combination on the card to establish his
identity. These systems can all be defeated, due to their invariant
operational sequences, by an unauthorized person who observes a
true card bearer the verifier and who subsequently comes into
possession of the card.
SUMMARY OF THE INVENTION
This invention overcomes the problems discussed above by
introducing a randomly varying operational sequence feature into
combination switching devices. Briefly, according to the invention,
a random word is loaded into a plural stage shift register provided
with indicator lights or the like to show the condition of each
stage. In one embodiment, preselected stages of the register are
connected to a plurality of AND gates constituting a decoding
network such that for any given condition of the preselected
stages, only one AND gate will have a raised output. The authorized
operator, having knowledge of the preselected stages, or
combination, observes their conditions or states and then selects
the proper AND gate by closing a corresponding switch. This
supplies a pulse to a correct selection counter and also loads a
new random word into the shift register. The AND gate selection
operation is then continuously repeated in this manner, each time
with a different random word in the register, until the counter
reaches a predetermined value, at which time an output signal is
issued which actuates the lock mechanism, verification light, etc.
Incorrect AND gate selections reset the counter and actuate an
alarm device.
Since a bare observer does not know which register stages are
involved in the combination, he has no way of knowing which
indicator lights the operator is looking at in making the proper
AND gate selection, and since the selected gate varies in a
completely random manner according to the random words in the
register, he is unable to break the combination even after
observing the operation of the device.
In an alternate embodiment of the basic device, the preselected
stages are individually coupled to a single AND gate by single
pole-double throw switches to implement the decoding function. This
achieves the same overall result at a considerable savings in
circuitry, as will be developed below. A modified form of this
embodiment includes means responsive to the reverse or improper
selection of all of the switches for opening the lock and at the
same time actuating a remote alarm. This is an antiambush feature
whereby an operator, under the threat of physical violence, may
comply by opening the lock while simultaneously, but in an
undetected manner, generating an alarm signal.
In the card verification embodiment, circuit means carried on the
card effect the electrical connections between the preselected
register stages and the decoding network. Thus, only the authorized
card bearer, having knowledge of the stages selected by the card
circuitry, is able to successfully operate the device.
In a further embodiment adapted for operation by two different
persons, each possessing only half of the overall combination, the
register, decoding network and counter are duplicated, with
different preselected stages in the second register being connected
to the corresponding decoding network. The first person then
operates half of the device until the first counter registers an
output signal, after which the second person operates the other
half of the device, using a different combination known only to
him, until the second counter produces an output. When the outputs
from both counters are raised, a final output signal is produced to
actuate the utilization device.
It would also be feasible to have data from one half of the device
telemetered to a remote location over a telephone line or by other
suitable means of communication for the purpose of operation by a
remote operator. For example, a central bank office could control
the vaults in all of its branch offices.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and advantages of the
invention will be apparent from the following more particular
description of a preferred embodiment of the invention, as
illustrated in the accompanying drawings in which:
FIG. 1 shows a block diagram of an electronic combination switching
device constructed in accordance with the teachings of this
invention,
FIG. 2 shows a typical control panel for operating the circuit of
FIG. 1,
FIG. 3 shows a block diagram of a portion of an alternate
embodiment adapted for operation by two different persons,
FIG. 4 shows a portion of an alternate embodiment adapted for I.D.
or credit card verification,
FIG. 5 shows an alternate embodiment of the invention shown in FIG.
1 employing simplified circuitry, and
FIG. 6 shows a portion of an alternate embodiment of the invention
shown in FIG. 5 incorporating an antiambush feature.
DESCRIPTION of THE PREFERRED EMBODIMENT
Referring now to FIG. 1, the operation of the device is initiated
by momentarily closing start switch 20, which triggers the
monostable multivibrator of Single Shot 22 from the filtered power
supply 24. Diode 25 isolates the remaining portions of the
circuitry from the initial start signal. The raised output from the
Single Shot conditions AND gate 26 and simultaneously actuates a
random bit generator 28. Such generators are well known in the art
and will not be described herein in detail. The random pulse train
output from the generator passes through AND gate 26 into an eight
stage shift register 30 where it is stepped along to the right in
FIG. 1 by a clock source, not shown, synchronized with the
generator bit rate. After a predetermined time delay sufficient to
permit the complete loading of the register, the output from Single
Shot 22 drops to deenergize the generator 28 and disable AND gate
26. At this point, the shift register 30 is fully loaded with a
random 8 -bit word, and the condition of each stage, either on or
off, is shown by its corresponding indicator light 32. In the
example shown, stages 1, 2, 4 and 7 are on while stages 3, 5, 6 and
8 are off.
Each register stage is provided with both on and off sense lines
34, as shown, which have raised signal levels depending upon
whether their corresponding register stages are on or off. If
stages 3 is off, for example, the "3" sense line will have a
lowered signal level while the "3" line will have a raised signal
level.
In FIG. 1, the sense lines 34 of register stages 1, 5 and 7 are
shown, by way of example, as being coupled to AND gate decoding
network 36 by an interconnection matrix 38. The decoding network
comprises eight AND gates 40, 42, 44, 46, 48, 50, 52 and 54 each
having three inputs. The number of register stages is completely
arbitrary, 8 being shown in FIG. 1 by way of example only. The
number of AND gates in the decoding network is determined by the
number of register stages selected for the combination, and is a
power of two functions. Thus, if four stages had been selected,
sixteen AND gates would be required.
It will be noted that the sense lines for register stage 5 are
connected to the first inputs of each AND gate, or the inputs
furthest to the left in FIG. 1. The sense lines for register stage
1 are connected to the second or middle inputs of each AND gate,
and the sense lines for register stage 7 are connected to the third
inputs, or those furthest to the right, of each gate. This yields a
combination of 517. It will be further noted that the numbers in
the combination may be in an ascending, descending, or mixed order.
With an eight stage register, for example, there are 8 .times.7
.times.6 or 336 possible three-number combinations involving no
repeating numbers.
The authorized operator, knowing the combination to be 517,
observes the indicator lights of these three stages and notes that
stage 5 if off, stage 1 is on and stage 7 is on. This tells him
that only AND gate 52, which decodes the off, on, on or
-++sequence, has a raised output, and he therefore closes switch
S52 associated with AND gate 52.
The operator would not be required to memorize the decoding
function associated with each AND gate or corresponding switch
since same could be shown on a control panel, as illustrated in
fig. 2, above each switch toggle in a plus, minus manner.
The closure of switch S52 produces a raised signal on line 56 which
is applied to the toggle of count input of a three-stage, binary,
correct selection counter 58 and to the reset input of a two-stage,
binary, alarm counter 60. The signal applied to counter 58
registers a count of one.
Each of switches S40 --S54 is individually ganged to switch 68, as
indicated by the broken line 70, but switches S40 --S54 are not
ganged or connected to each other in any way. The closure of switch
S52 thus closes switch 68 which again triggers Single Shot 22 to
energize generator 28, enable AND gate 26 and load a new random
work into the shift register 30. AND gate 62 lowers the output of
Inverter 64.
The operator now repeats the procedure outlined above by observing
the indicator lights of register stages 5, 1 and 7 and closing the
switch corresponding to the AND gate in decoder network 36 having a
raised output. Each correct selection and switch closure increments
counter 58 by one and loads a new random word into the register.
This procedure is repeated until counter 58 reaches a predetermined
count which produces a final output signal from AND gate 72. Output
terminal 74 may be coupled to any suitable utilization device, such
as an operation relay or a lock mechanism. Counter 58 may, of
course, be decoded by AND gate 72 for any desired value. With the
connections shown in FIG. 1, for example, a final output signal is
produced when the counter reaches a value of five, corresponding to
five successive correct selections.
If an improper selection is made, the output from Inverter 64
remains raised, and, since the closure of switch 68 couples the
power supply 24 to AND gate 62, the latter raises its output to
reset selection counter 58 and toggle alarm counter 60. If three
successive improper selections are made, AND gate 76 produces an
output at terminal 78, which may be coupled to an alarm device.
Counter 60 may be decoded by AND gate 76 at any desired value,
three having been chosen in FIG. 1 by way of example only.
Counters 58 and 60 may be initially reset by separate circuitry,
not shown, coupled to start switch 20.
The embodiment shown in FIG. 3 is adapted for operation by two
different persons, each possessing only half of the overall
combination. The circuitry of FIG. 3 essentially duplicates much of
that shown in FIG. 1 and operates in the same manner. Shift
register 30' is loaded from random bit generator 28 through AND
gate 26, and the closure of any one of switches S40'--S54' also
closes switch 68 in FIG. 1 to generate a new random word. In
operation, the completion of the procedure described above with
respect to FIG. 1 by the first person conditions AND gate 80 in
FIG. 3 rather than directly opening the lock. The second person
then operates the FIG. 3 circuitry, using a different combination
provided by interconnection matrix 38', until the counter 58'
reaches a count of five. AND gate 72' then raises its output, which
actuates AND gate 80 and produces a final output signal at terminal
82. Both sections or halves of the device may, of course, be
operated simultaneously by the two persons involved, since each
half is wired for a different combination, and neither person is
able to determine the other's combination by mere observation.
A further consideration in the operation of this device is the ease
with which it can be adapted to the function of a secure remote
control device.
It would be feasible, for example, to have all of the device
installed at one location with the exception of the display which
could be located remotely. The person who wanted to operate the
lock would then have to contact the person who has custody of the
display. This contact could be established through the
authenticating-device embodiment of this invention. The person at
the lock would initiate the random word loading and the contents of
the shift register would be telemetered to the display. The person
at the display would relay the display information back to the
person at the lock.
It would also be feasible to have the entire operation performed by
remote stations. This type of operation, for example, would permit
full control of all the vaults in branch banks by the main office.
It could also be used to allow access to certain areas only through
a main office.
Another variation of the device could be the location of the
display in one remote place and the location of the switches in a
different remote place. The operator at the display would inform
the operator at the switches by a suitable means of communication
what the display reading is for each cycle of operation.
In the FIG. 4 embodiment, adapted for I.D. or credit card
verification, the interconnection matrix 38 is replaced by a card
insert station 84 having a card accommodating slot 86 provided with
upper and lower electrical contact brushes 88. When a card 90,
carrying electrical circuitry for effecting the necessary
connections between the preselected register stages and the
decoding network, is inserted in slot 86, only the authorized
bearer, having knowledge of the combination provided by the card,
can successfully operate the device to establish his identity.
The decoder shown in FIG. 1 consists of 8 AND gates. Each AND gate
is connected to the three selected stages of the shift register in
a unique manner. The AND gates therefore provide a binary-to-octal
converter. One of the AND gates will be in a conducting state for
each possible combination of bits in the selected stages. The
operator must determine which gate is conducting through his prior
knowledge of the lock. It is necessary for the operator to mentally
decode the pattern and make a selection by choosing the appropriate
switch at the decoder output.
In an alternate embodiment of the invention, shown in FIG. 5, the
decoder and the operation of the device can be simplified in the
following manner. Referring to FIG. 5, the preselected stages of
the shift register 30 are coupled to single-pole double-throw
switches 94, 96 and 98. The center taps of each switch are coupled
to the inputs of an AND gate 100. If the operator now turns those
switches associated with the register stages in the ONE state to on
and those switches associated with the register stages in the ZERO
state to off, and AND gate will be energized. The operator may then
press switch 102 thereby entering a count in the correct selection
counter 58 and initiating a new cycle of operation. An incorrect
selection will toggle the alarm counter 60 as described above in
connection with FIG. 1.
This embodiment has the following advantages over that described in
FIG. 1. Only one AND gate is needed; the number of switches
required is reduced; and the operation is simplified. An operator
is only required to know which lights in the light display field
are used in the combination, and which switch is associated with
each of those lights. He then presses the switch on or off
depending upon the state of the associated lights. In so doing he
connects the appropriate inputs to the AND gate 100 and the
decoding function is automatically performed.
In the antiambush modification shown in FIG. 6, the outputs from
switches 94, 96 and 98 are coupled to AND gate 100, as in FIG. 5,
and in addition, they are fed through Inverters 104 to AND gate
106. The output from the latter is fed to OR gate 108 along with
the output from AND gate 100, and the OR gate output is supplied to
the upper terminal of switch 102. The output from AND gate 106 is
also fed to the alarm terminal 78 through OR gate 110. The alarm
terminal may lead to either a local or a remote alarm device. If
improper or reverse selections are made on all three switches, such
as by turning switches 94 and 98 off and switch 96 on, negative or
lowered signal levers with appear on all of the switch outputs,
thus blocking AND gate 100. The Inverters 104 raise the three
switch signals, however, which in turn raises the output of AND
gate 106, OR gate 108 and OR gate 110. The raised signal from OR
gate 108 permits the correct selection counter to be toggled in the
usual manner upon the closure of switch 102, thus enabling the lock
to be operated in a seemingly normal manner. The output from OR
gate 110, appearing at the alarm terminal 78, may actuated a remote
alarm, however, to alert the proper authorities that someone is
being forced to open the lock.
An alternate to the use of the random bit generator is to employ
the shift register as part of a pseudo random sequence generator.
This is accomplished by the addition of a multi-input modulo -2
adder. The inputs to the adder are taken from selected stages of
the shift register. The adder output is returned to the shift
register input. This configuration is known in the art as a
sequence generator and depending upon the configuration of taps
used will generate sequences exhibiting random properties.
While the invention has been particularly shown and described with
reference to preferred embodiments 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.
* * * * *