U.S. patent number 3,868,057 [Application Number 05/366,762] was granted by the patent office on 1975-02-25 for credit card and indentity verification system.
Invention is credited to Robert C. Chavez.
United States Patent |
3,868,057 |
Chavez |
February 25, 1975 |
CREDIT CARD AND INDENTITY VERIFICATION SYSTEM
Abstract
An improved form of credit or identification card and a system
for verifying the propriety of ownership thereof. The card
comprises, in addition to the conventional embossed indicia which
ordinarily includes a name and an account number, a laminated or
encapsulated center layer of material upon which is deposited an
electrical circuit consisting of a matrix of electrical conductors
and semiconductors coupled to a plurality of contact points. At
least three of the contact points are coupled to certain ones of
the semiconductor devices thereby providing a code number unique to
each card and the remaining contacts are coupled to other parts of
the circuit to give a false code. A card verifier has a like
plurality of electrical contacts adapted to engage the card
contacts and a plurality of selectors for selectively coupling the
circuit in the card with a circuit in the verifier so as to produce
a YES or NO output signal to verify selection of the proper code
number.
Inventors: |
Chavez; Robert C. (Las Vegas,
NV) |
Family
ID: |
22565936 |
Appl.
No.: |
05/366,762 |
Filed: |
June 4, 1973 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
157928 |
Jun 29, 1971 |
|
|
|
|
Current U.S.
Class: |
235/380; 235/443;
235/492; 283/904; 235/487; 235/488; 283/83; 340/5.86 |
Current CPC
Class: |
G06K
19/067 (20130101); G07F 7/1008 (20130101); G06K
7/065 (20130101); G07F 7/10 (20130101); G07F
7/1058 (20130101); G06Q 20/347 (20130101); G07F
7/1025 (20130101); Y10S 283/904 (20130101) |
Current International
Class: |
G07F
7/10 (20060101); G06K 19/067 (20060101); G06K
7/06 (20060101); G06k 005/00 (); G06k 007/06 ();
G06k 019/06 () |
Field of
Search: |
;235/61.7B,61.11A,61.11C,61.12N,61.12C ;340/149A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Cook; Daryl W.
Attorney, Agent or Firm: Lyon; & Lyon
Parent Case Text
This is a continuation-in-part of my previous application, Ser. No.
157,928 filed June 29, 1971, now abandoned.
Claims
I claim:
1. An improved identity verification system, comprising:
a card, a plurality of contact points situated upon said card,
first and second circuit means embedded within said card, three or
more of said contact points being coupled to said first circuit
means and providing a unique set of contact points, the remainder
of said contact points being coupled to said second circuit
means;
card reader means comprising contact means for establishing
electrical contact with each of the contact points of said card,
third circuit means in said reader means, a plurality of selector
means electrically coupled between said contact means and said
third circuit means for selectively coupling individual ones of
said contact means to said third circuit means; and
indicator means coupled to said first and third circuit means, said
indicator means providing an output signal when said first and
third circuit means are coupled together.
2. The system set forth in claim 1 wherein said indicator means
includes first and second output means, said first output means
providing a first output signal when all of said contact points are
coupled to said first circuit means, and said second output means
providing a second output signal when any of said contact points
are coupled to said second circuit means.
3. The system set forth in claim 1 wherein said first circuit means
comprises a three terminal semiconductor device.
4. The system set forth in claim 1 wherein said first circuit means
comprises a unijunction transistor.
5. The system described in claim 1 wherein said first circuit means
comprises a NAND gate.
6. The system described in claim 3 wherein said second circuit
means comprises a plurality of diodes coupled in randomly-oriented
fashion between various of said contact points.
7. The system described in claim 1 wherein:
said first circuit means comprises a unijunction transistor, the
three terminals of which are connected to three individual ones of
said contact points; and
said second circuit means comprises a plurality of diodes coupled
in randomly-oriented fashion between all the remaining ones of said
contact points.
8. The system described in claim 1 wherein:
said first circuit means comprises a NAND gate having two input
terminals, one output terminal and two bias terminals, each of said
terminals being connected to individual ones of said contact
points; and
said second circuit means comprises a plurality of diodes coupled
in randomly-oriented fashion between all the remaining ones of said
contact points.
9. The system described in claim 1 wherein:
said first circuit means comprises a first plurality of
silicon-controlled-rectifiers coupled in series circuit
relationship, each of said rectifiers having a gate electrode
coupled to one of said contact points which define said unique set
of points, the last in said series of rectifiers having an output
conductor coupled to said indicator means;
said second circuit means comprises a second plurality of
silicon-controlled-rectifiers coupled in parallel circuit
relationship, each of said rectifiers having a gate electrode
coupled to one of the remainder of said contact points, said second
plurality of rectifiers having an output conductor coupled to said
indicator means.
10. The system set forth in claim 9 werein said indicator means
comprises a light-emitting diode coupled to the output conductor of
said first rectifiers, a silicon-controlled-rectifier coupled in
parallel with said diode, said silicon-controlled-rectifier having
a gate electrode coupled to the output conductor of said second
plurality of rectifiers.
11. The system described in claim 1 wherein said card reader
includes means for selectively sensing said contact points, said
means comprising means for receiving a card in the reader, contact
means in said receiving means for contacting each of said contact
points, a plurality of switching means coupled to said contact
means for selecting certain ones of said contact means according to
the aforesaid system of index numbers assigned to the contact
points on a card, said switching means having indexing means for
selecting contact points according to said series of code
numbers.
12. The system described in claim 11 wherein said indicating means
in said card reading means comprises a fourth circuit means, said
fourth circuit means having first and second output indicating
devices, a source of electrical power, means for coupling said
source of power to said switching means, current responsive means
coupled to said switching means and said indicating devices, said
current responsive means being operative to energize said first
output device when said switching means is coupled only to said
first circuit means in a card, said current responsive means
operative to energize said second output device when said switching
means is not coupled only to said first circuit means.
13. An improved identity verification system, the combination
comprising:
a card, first and second circuit means embedded in aid card, a
plurality of contact points upon said card, said contact points
disposed in a matrix pattern, said first circuit means being
coupled to more than two but substantially less than all of said
contact points, said second circuit means being coupled to all of
the remaining contact points;
a card reader having means for receiving a card therein, contact
means situated in said receiving means, said contact means disposed
in a matrix pattern adapted to register with the contact points of
a card, third circuit means situated in said card reader, selector
means coupling said third circuit means to said contact means
whereby any one of said contact points of a card may be coupled
into said third circuit, said third circuit means including
indicator means, said third circuit means being operative to
provide an output at said indicator means when said selector means
has been actuated to couple only said first circuit means to said
third circuit means.
14. An improved identification card and a system for verification
thereof comprising, in combination:
a card comprising at least two lamina adhered together, said card
having a matrix of electrical contact points disposed upon a
surface of one of said laminae, access means formed upon one or
more surfaces of said card for permitting access to said contact
points, a first plurality of semiconductor means disposed within
said matrix and interconnecting substantially all of said contact
points in random fashion, one or more second semiconductor devices
having three or more terminals, said terminals being connected to
individual remaining ones of said contact points thereby defining a
unique combination of points within said matrix;
a card reading apparatus for verifying ownership of said card, said
apparatus having means for receiving a card therein, a plurality of
contact means situated within said receiving means for making
electrical contact with the aforesaid contact points of said card,
selector means coupled to said contact means for selecting
individual ones of said contact points, circuit means coupled to
said selector means, said circuit means including means responsive
to the aforesaid second semiconductor devices to produce a unique
output signal when said selector means has been actuated to couple
said second semiconductor devices to said circuit means.
15. The system described in claim 12 wherein said current
responsive means comprises a relaxation oscillator.
16. The system set forth in claim 1 wherein said first and second
circuit means of said card have portions thereof coupled together
therein whereby external electrical measurements taken at said
contact points will not indicate which contact points are unique to
said first circuit means.
17. The system as set forth in claim 9 wherein said first and
second circuit means of said card have portions thereof coupled
together therein whereby external electrical measurements taken at
said contact points will not indicate which contact points are
unique to said first circuit means.
18. An improved identification card verification system
comprising:
a card having a plurality of contact points situated thereon
defining a matrix, first and second circuit means embedded within
said card, said first circuit means comprising one or more first
circuit components coupled to selected ones of said contact points,
said selected contact points thereby defining a unique code number
within said matrix, said second circuit means comprising a
plurality of second circuit components coupled to the remainder of
said contact points of said matrix, said second circuit components
having individual electrical characteristics substantially similar
to said first circuit components, said remainder of contact points
coupled to said second components thereby defining false code
numbers within said matrix;
card reading means comprising contact means for simultaneously
establishing electrical contact with all of the contact points of
said card, third circuit means, coded selector means coupled
between said contact means and said third circuit means, and
indicator means coupled to said third circuit means for indicating
whether or not said coded selector means has coupled the contact
points of said first circuit means with said third circuit means
according to said unique code number.
19. An improved identification card verification system
comprising:
a card having a plurality of contact points situated thereon
defining a matrix, first and second circuit means embedded within
said card, said first circuit means comprising one or more first
circuit components coupled to selected ones of aid contact points,
said selected contact points thereby defining a unique code number
within said matrix, said second circuit means comprising a
plurality of second circuit components coupled to the remainder of
said contact points of said matrix, said second circuit components
having individual electrical characteristics substantially similar
said first circuit components, said remainder of contact points
coupled to said second components thereby defining false code
numbers within said matrix;
card reading means comprising contact means for simultaneously
establishing electrical contact with all of the contact points of
said card, third circuit means, coded selector means coupled
between said contact means and said third circuit means; and
indicator means coupled to said first and second circuit means,
said indicator means including means providing a visual indicator
when said first circuit means has been coupled to said third
circuit means according to said unique code number, said visual
indication means providing no visual indication whenever any
portion of said second circuit means is coupled to said third
circuit means.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a credit card system
which makes possible the virtual elimination of credit card misuse.
The ensuing description deals with the use of the invention as a
credit card, although it will be apparent that potential scope of
the invention would include any use as a positive means of
identification. The advent of credit cards for the convenient
acquisition of goods and services in lieu of the use of currency
has carried with it considerable problems in what may be generally
called credit card misuse. Misuse of credit cards includes the use
by others of cards which have been either lost or stolen,
unpremediated felonious users who have received unsolicited credit
cards in the mail, but who deny having used them, outright
counterfeiting of credit cards, and the use of cards by the
rightful owner thereof beyond the agreed credit limits. In such
cases, substantial financial liability may be borne by either the
credit card holder, the credit card company or both, and recent
reports have indicated that losses sustained on account of credit
card misuse total in the hundreds of millions of dollars annually.
It is submitted that such losses are sustained as a direct result
of the fact that credit card misuse is relatively easy to commit by
those persons so disposed because of the lack of a positive and
easy means of identification.
Most credit cards currently in use have a place for the signature
of the authorized user but this proper signature is seldom, if
ever, checked or compared with the actual user's signature because
the clerks handling an individual transaction are not competent to
analyze the handwriting. Other credit cards currently in use have a
picture of the authorized user but again this is not a positive
means of identification, it is an inconvenience when the rightful
user desires to permit another to use his card, and it certainly
does not prevent counterfeiting. Other methods of positive
identification have been proposed, such as a fingerprint check or a
magnetically-encoded strip of material on the card which can be
read by an appropriate card-reading device but these systems are
very costly to implement.
SUMMARY OF THE INVENTION
The foregoing shortcomings may be eliminated through the use of the
present invention inasmuch as the credit card herein proposed is
provided with a secret code number which shall be known only to the
rightful user thereof. When the holder of the credit card desires
to use it, it is inserted in a verification device and the rightful
user thereof selects by means of appropriate control on the
verification device the code number known only to him and when he
selects the proper series of numbers, there will be a visual
indication that the number encoded on the card corresponds with the
number selected by the card user. Obviously, not knowing the proper
number, one who finds or steals the card will not be able to use
it. The manner in which the code number is encoded on the card
makes it extremely difficult to ascertain the correct code
number.
In one embodiment the credit card contains a matrix of contact
points, ideally a hundred or more and each contact point can then
be assigned a code according to a numerical or alpha-numerical
system. Each of the contact points is interconnected with the other
by thin deposits of electrical conducting material but rather than
being directly connected to one another each of the points is
electrically connected to a small deposit of semiconductor material
which in the form of diode provides a finite electrical resistance
between any two points. Three or more of these contact points are
not interconnected in the manner just described but in turn are
electrically connected to a semiconductor device having three or
more terminals, such as a transistor. The contact points which are
connected to the semiconductor device are selected at random in the
matrix. It is these three or more points which determine the unique
code number for the individual card, as determined by the coding
system.
The card verification device contains a plurality of sensing
devices adapted to contact the contact points on the card when the
card is inserted in the device. The verification device also
contains a number of selectors by which the card user selects the
contact points corresponding to the code or index number so that
the device electrically connects to the three or more terminals
which communicate with the semiconductor device. By this method,
the semiconductor device is coupled to a circuit in the
verification device so that an electrical circuit is completed
whereby current will be conducted to indicate a proper selection of
code numbers. If the incorrect number is selected, the circuit
within the verification device will not be properly completed and
an error signal will result. The interconnection of all of the
unused contact points through semiconductor material renders it
extremely difficult to ascertain the proper code number inasmuch as
resistance measurements made upon the card using an ohmmeter, for
example, will provide confusingly false readings between any two
contact points whether the meter is attached to the proper contact
points or not. Thus, resistance measurements made upon all of the
contact points trying all of the various combinations will not
permit a wrongful possessor of the card to determine the proper
code number.
In a modified form of the invention a unique coding circuit
employing a series of SCR's is embedded in the card and due to the
configuration of this circuit the number of contact points on the
card, and therefore in the verifier as well, is reduced to a small
number. This circuit still provides a very large number of possible
combinations while also providing false code indications if effort
is made to decode the same.
It is an object therefore of the present invention to provide a
credit card and a credit card verification device whereby improper
use can be substantially eliminated.
It is also an object of the present invention to provide an
improved credit card system whereby the proper owner of a credit
card may utilize it without fear of financial liability on account
of loss or theft and in addition permitting the credit card company
to utilize the card verification device for accounting
purposes.
It is a further object of the invention to provide a credit card
verification system which will substantially facilitate the
recovery of lost or stolen cards.
Further objects and advantages of the present invention will be
readily apparent upon reading the ensuing detailed description in
conjunction with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial representation of a form of a credit card
verification device showing a credit card in association
therewith.
FIG. 2 is an exploded perspective view of a credit card made in
accordance with one embodiment of the present invention.
FIG. 3 is an enlarged sectional view showing the relationship of
the credit card verifier and the credit card.
FIG. 4 is an enlarged plan view of one embodiment of the
intermediate layer showing the matrix arrangement and
semiconductors thereon.
FIG. 5 is a circuit diagram of one embodiment of the electrical
portion of the credit card verifying device.
FIG. 6 is a plan view of the intermediate layer of the card showing
another embodiment thereof employing a NAND gate.
FIG. 7 is another circuit diagram for an alternative electrical
portion of the card verifier.
FIG. 8 is the equivalent circuit for the NAND gate employed in FIG.
6.
FIGS. 9a and 9b are circuit diagrams of another embodiment of the
present invention showing an improved and simplified coding circuit
for the card in FIG. 9a and a simplified code selection and
verification circuit in FIG. 9b.
DESCRIPTION OF THE FIRST EMBODIMENT
As shown in FIG. 1, the new credit card generally designated 10
comprises three initially separate layers of material which are
subsequently permanently bonded together. As is the current
practice, the materials used in the three separate layers may be
any suitable, somewhat rigid plastic. The top layer 12 would have
the same general appearance as do most credit cards today including
the name 13 of the credit card holder, his account number 14 and an
insignia or name indicating the credit card company as represented
by the design 15. The name 13 and the account number 14 are
ordinarily embossed on the surface of the card and provide a means
for imprinting the name and account numberon invoices. When
constructed in this manner, the credit card of the present
invention is compatible with credit card imprinting devices
currently in use but it is contemplated that the credit card
verification device disclosed herein may also incorporate the
details of credit card invoice printing devices although it is not
deemed necessary to show the details of such construction inasmuch
as they are well known in the art.
The bottom layer of the card 16 is a substantially flat member with
no raised or embossed indicia thereon but is provided with a
plurality of spaced apertures 18 which are symmetrically located
over the entire surface of the bottom layer 16 in a grid or matrix
fashion defining a system of coordinates. The purpose of the
apertures 18 is to provide access to contact points in the interior
of the card as will soon be readily apparent.
The middle layer or lamina 20 is also a substantially flat, thin
piece of pliable plastic material which is electrically
nonconductive as are layers 12 and 16. on the surface of lamina 20
which when bonded will be facing the bottom layer 16 there is
deposited or etched a plurality of electrical contact points 22.
Contact points 22 are symmetrically arranged on this surface of
layer 20 in the same manner as are the apertures 18 in layer 16
providing a system which can be described by numerical or
alpha-numerical coordinates and these contact points are positioned
to coincide with apertures 18. As shown in FIG. 2 and more
completely in FIGS. 4 and 6, deposited on the surface of lamina 20
are a plurality of diodes 24. Each of the contact points 22 is
connected to one or more of these diodes by means of conductor
paths 26 which are also etched upon the surface of lamina 20. The
diodes are thus connected in strings, the polarities being
alternated at random, and the strings not necessarily connected
together. The exception to the foregoing statement is that three or
more of these contact points will not be interconnected to these
diodes but will be connected to a semiconductor device.
FIG. 4 shows one embodiment of the invention in which the
semiconductor is a unijunction transistor 28 deposited upon a
surface of intermediate layer 20 which can be made, according to
present technology very small so as not to provide a bulky area or
excess thickness in the card. Unijunction 28 has an emitter
electrode 30, and two base electrodes 32 and 34. Each of these
electrodes is connected through an etched-on circuit path,
respectively to selected ones of the contact points 22a, those
contact points being ones which are not interconnected to any of
the diodes 24. As shown in FIG. 4, in which the set of coordinates
established by the contact points is numbered from left to right,
it is shown that the emitter electrode 30 is connected to the
contact point indexed No. 56, the base electrode 32 is connected to
the contact point indexed No. 22 and the other base electrode 34 is
connected to the contact point indexed No. 108. Thus, the code
number established by the coordinates for the card shown in FIG. 4
is the number 56-22-108.
Turning now to the details of the card verification device, this is
pictorially represented in FIG. 1 and indicated generally by the
numeral 40. The device 40 includes a slot 42 into which the card to
be verified shall be inserted. It would be desirable, in order to
assure that the card is properly inserted in the slot 42 to provide
the card with some sort of indexing means. It should be obvious
that because the contact points are indexed according to a certain
numerical order, it is necessary that the card not be reversed.
Thus, the card could have a notch cut in one end as shown at 41 in
FIG. 1 which would permit the card to be inserted all the way into
slot 42 there being an embossment 43 (See FIG. 3) which would be
received in notch 41 to permit the card to be inserted all the way.
The exterior of the card reading device has a number of selector
knobs on the exterior thereof. The first series of knobs 44, 45 and
46 are multiple position rotatable switches used to select an index
number. Another series of knobs 47, 48 and 49 are again multiple
position switches having three or more positions which select which
set of the series of numbers in the combination shall correspond to
the number selected by the corresponding number selection switch.
In other words, in order to prevent someone from learning the
combination of the credit card, the user may select switch 48 to be
the first digit whereupon he will set that to the first digit
position and then set dial 45 to his first number, in our case that
being number 56 then he might select the knob 47 to be the second
digit whereupon he will adjust knob 44 to number 22, and so on.
After having properly adjusted all of these knobs, the card holder
or the attendant depresses button 50 and if the proper card has
been properly inserted and the numbers properly selected as
aforesaid, an indicator light 52 will be lighted indicating and
thereby verifying that the card holder is in possession of a proper
card.
As previously described, bottom layer 16 of the card is provided
with a series of apertures 18. In FIG. 3, the card 10 is shown
inserted in slot 42 with the bottom layer 16 facing downwardly. In
the interior of slot 42 there is positioned a plurality of contact
members 54 herein shown as electrically conducting spheres. The
contact spheres 54 are held in place by a perforated plate 56
having apertures 58 therein, the diameter of which is slightly less
than the diameter of spheres 54. The spheres are biased upwardly by
springs 60 which also provide electrical conducting paths and to
which are connected conductor leads 62. It should be apparent that
when card 10 is properly inserted all the way in slot 42 all of the
contact spheres 54 will reside in the apertures 18 providing
electrical connections to each contact point 22.
FIG. 5 shows one embodiment of an electrical circuit diagram
contained in the card verification unit 40 specifically a circuit
to operate in conjunction with the unijunction device shown in FIG.
4. The three coordinate number selecting switches 44, 45 and 46 are
shown with the contacts being dependent upon the number of contact
points designed to be on each card. To the contact points 64 are
connected the conductors 62 which connect to the spring contacts as
previously described. It should be apparent that all of the
contacts 64 assigned No. 1 are connected to spring contact No. 1
and so on. The wiper 66 of selector switch 44 connects through
condctor 68 to one of the terminals of each of the digit selector
switches 47, 48 and 49. Likewise, the wipers of the other number
selecting switches 45 and 46 connect to corresponding terminals on
digit selector switches 47 and 48.
Assuming the digit and number selectors are properly set, line 72
connected to wiper 70, will be coupled to the emitter 30 of
unijunction 28, line 74 connected to wiper 76 will be coupled to
one base 32 and line 78 connected to wiper 80 will be coupled to
the other base electrode 34. Conductor 72 is connected to junction
point 82 between capacitor 84 and variable resistor 86 which are
coupled in series. Capacitor 84 is connected to the negative ground
bus 88 to which is connected the negative terminal of battery 90.
Resistor 86 is coupled through positive bus line 87 to push button
switch 92, relay contact 98a and power switch 94 to the positive
terminal of battery 90. Line 74 is connected through series
resistor 96 to positive bus line 87. Line 78 is connected to one
side of relay coil 87. Line 78 is connected to one side of relay
coil 98 the other side of which is connected to negative bus 88.
Relay coil 100 is coupled in series with resistor 102 between
negative bus 88 and positive bus 87. Relay contact 100a is normally
open (operated in response to current in relay coil 100) is coupled
across switch 92.
Lamp 104 is coupled in series with relay contacts 98b and 100b,
both of which are normally closed, between negative bus 88 and
positive bus 87. Lamp 106 is coupled in series with relay contact
100c, which is normallyopen, between negative bus 88 and positive
bus 87. In this configurations as properly connected to the
unijunction transistor, the circuit is a relaxation oscillator,
lamp 104 indicating when power normally open on and lamp 106
indicating proper interconnection Of the unijunction into the
oscillator circuit.
Following are typical types and values of the circuit elements
employed in this circuit:
Unijunction transistor 2N1671B Texas Inst. Capacitor 84 100
Microfarad Resistor 86 1 Megohm Resistors 96, 102 330 ohm Relays
98, 100 WABCO No. 6739, 26.5VDC, 700 Ohm Power supply 24 VDC
When power switch 94 is closed, lamp 104 lights indicating the
system is ready. The DC voltage is applied across the push button
switch 92 which when depressed applies current through relay coil
100 closing contacts100a across the switch 92, and opening contacts
100b with the result that lamp 104 goes out. At the same time
contacts 100c close turning on lamp 106. Release of switch 92 will
not change this condition. DC power will also be applied to base
electrode 32 through resistor 96 and current will also flow through
capacitor 84 starting it to charge. After a specific time
determined by the values of resistor 86 and capacitor 84, the
charge on the capacitor will bias the emitter 30 sufficiently to
cause unijunction 28 to conduct. When it conducts, capacitor 84
discharges through base electrode 34 and through relay coil 98. The
current through coil 98 being sufficient to momentarily energize
the relay, contacts 98a and 98b both open, cutting off current to
relay 100 and thereby returning the entire circuit to its original
state.
The flashing sequence of lamps 104 and 106 indicates proper
connection of the card into the circuit. If lamp 106 is green and
lamp 104 is red, the sequence will be first a green light, then
upon depressing switch 92 a red light for a preset time, followed
by a green light again.
Improper connection of the card contacts into this circuit will
cause either no change in the initial green light signal or other
sequences all indicating wrong code selection. For example, if
conductors 74 and 78 were connected across a diode of the wrong
polarity, relay 100 would energize turning on the red lamp, but
relay 98 will never energize so the red lamp will remain lit. If
conductors 74 and 78 were conducted across a diode of proper
polarity both relays will energize but contact 98a will keep
opening and closing causing lamps 104 and 106 to continue blinking
on and off as long as switch 92 is depressed. The same action will
occur if conductors 72 and 74 are coupled across a diode of either
polarity. Relay 98 will never energize, thus keeping the red lamp
106 on.
The chains of diodes 24 to which the unused contact points are
connected provide a means for giving erroneous electrical readings
between the inactive contact points so that someone trying to
electrically determine the combination number through resistance
measurements would not be able to do so. Resistance measurement
between contact points will indicate either a small finite
resistance representing the forward resistance of the diodes (about
200 ohms) or the unijunction or an open circuit indicative of the
back resistance of one or more diodes or the unijunction. The
forward resistance of the unijunction is E to B.sub.1,
approximately 200 ohms, E to B.sub.2 - 600 ohms and B.sub.1 to
B.sub.2 infinite To effectively decode the card would take a three
element resistance check and it should be recalled that there are
over one million possible combinations. With all of these
measurements. it is clear that the investigator has determined
nothing about the location of the proper contact points. A card
containing 100 electrical contact points, of which three are
active, provides one million possible combinations. Since the
correct selection of the switches 47, 48 and 49 is also required,
this multiplies the number of possible combinations by three. Four
terminal semiconductor devices are also available which if used
could raise the number of possible combinations to three hundred
million.
FIGS. 6 through 8 set forth another embodiment of the invention of
a more simplified form. Here, the operative semiconductor element
comprises a NAND circuit 120 deposited upon the intermediate lamina
20. NAND circuit 120 has input terminals 121 and 123 which are
coupled to unused contact points 122 and 124 respectively, and an
output terminal 125 connected to contact point 126. In addition,
the NAND circuit requires biasing, so the positive or B+ terminal
is connected to contact point 128 and the negative or B- terminal
is connected to contact point 130. because all cards using a NAND
circuit will require this biasing, contact points 128 and 130 may
preferably be additional to the contact points making up the
encoding grid and may be situated along the edges of the card.
Location of the biasing contacts within the encoding grid would of
course increase the number of possible code combinations but may
make false readings possible.
In FIG. 7, the switching apparatus previously described in
connection with FIG. 5 schematically designated by the boxes 132,
133 and 134 inasmuch as the details thereof are the same. Switches
132 and 133 couple the inputs 122 and 124 through a push button
switch 136 to a DC power supply 138 the output of which may be
aslow as 1 VDC. The output terminal 126 is coupled through switches
134, through Zener diode 140, to indicator lamp 142 to the negative
terminal 144 of supply 138. The negative supply terminal 144
couples directly to the card B- terminal 130. The positive supply
terminal 146 of approximately 4 VDC is coupled through power switch
148 to the B+ terminal 128. power lamp 150 is coupled across switch
148 and negative supply terminal 144.
When switched on, lamp 150 preferably green is it. If the proper
contact points the card are selected, depression of switch 136 will
produce an output at terminal 126 of sufficient amplitude to cause
Zener diode 140 to conduct, causing indicator lamp 142 to light,
signifying a proper code selection. Zener diode having a Zener
level of about 3 VDC will prevent improper input connections from
causing lamp 142 to light since the input signals are only about 1
VDC.
FIG. 8 is the equivalent circuit of a typical NAND gate employing
two transistors and appropriate biasing resistors. It will be
readily apparent that resistance measurements made attempting to
decode a card will not be fruitful because the overall diode matrix
will produce similar results. With the NAND gate biasing points
separate from the encoding matrix, it cannot be shorted to the
output, so a false reading cannot occur in that way either.
FIGS. 9a and 9b set forth an improved embodiment of the present
invention in that the circuitry therein shown provides the
previously discussed feature of having a single unique code
sequence for a card together with the provision of false code
indications so that the card cannot be easily decoded but this
embodiment permits the reduction of contact points on the card, and
therefore on the card verifying unit to a very low number while
still permitting an extremely large number of possible code
combinations. The obvious advantage of reducing the number of
contact points is that it will reduce the number of possible
mechanical failures in reading or verifying cards. It is apparent
that for a large number of contact points, it is possible that one
of the important contacts may become dirty and fail to make the
proper electrical contact with the verifier unit, or the spring
loaded contacts of the verifier unit may, upon continued usage,
suffer some mechanical defect which could result in wrongly failing
to properly verify a good card. It is important that the card
verifiers be dependable so that customers who use them and
proprietors who have them can maintain a high degree of confidence
in them.
The verification unit, the circuitry of which is shown in FIG. 9b
may be constructed in virtually any configuration, it being
necessary only that there be provided the number of contact points
to be hereinafter discussed together with a number of momentary
contact switches or push buttons and a pair of multi-positioned
rotary switches. It will be seen from the ensuing discussion that
the power supply requirement of this particular circuitry is
extremely low so that the unit can be small, portable and self
contained. The verification unit consists of 14 contact points
generally designated in FIG. 9b by the numeral 200 and these
contact points are indexed by the digits "0" through "9," letters
"A" and "B" and signs "-" and "+." Each of the contact points 200
is coupled to one terminal 202 of momentary push button switches
204. A first rotary switch 206 has a wiper arm 208 and a plurality
of contacts 210. A second rotary switch 212 is similarly provided
with a wipe arm 214 and a plurality of contacts 216. The switch
contacts 210 and 216 have, in addition to "off" positions to which
no connections are made, connections indicated by the arrows and
numered from "0" to "9" which are coupled in turn to the terminals
202 of the push button switches 204 numbered "0" through "9" and
"A" and "B" so that contacts 210 and 216 are coupled in parallel to
the correspondingly numbered push button switches, such as one-one,
two-two, etc. The exception to the foregoing manner of connection
is that one of the contacts 210a, which may be any of the numbered
contacts 210 is coupled through conductor 218 to terminal 202aof
push button switch 204a, which is in turn also coupled to the
contact designated by the letter "A." Similarly, one of the
contacts 216b of rotary switch 212 is coupled through conductor 220
to terminal 202b of push button switch 204b, that terminal also
being coupled to the contact indexed with the letter "B."
A power switch 222 has one contact coupled to a source of positive
DC voltage, herein designated as the B+ terminal 224 and, for
example, the value of the B+ voltage is indicated as 10.5 volts DC.
The other terminal of switch 222 is coupled to ground terminal 226.
All of the push button switches 204 have their other terminals tied
to a common bus line 228 which in turn is coupled to conductor 230
to the base electrode 232b of transistor 232. The collector 232c is
coupled through an appropriate biasing resistor 234 to the B+ line
235. The emitter 232e is likewise coupled to the B+line 235 through
biasing resistor 236, as is the base electrode 232b coupled through
resistor 238. The emitter 232e is similarly coupled through
resistor 240 to conductor 242 which is connected to the wiper 214
of switch 212. The wiper 214 is also coupled through a conductor
244 to the grounding terminal 226 of switch 222. The circuit also
includes a capacitor 246 coupled between base electrode 232b and
ground conductor 242.
The emitter 248e of transistor 248 is connected directly to the B+
line 235, the collector electrode 248c is coupled to the wiper 208
of rotary switch 206. Thus, power is supplied to the circuit upon
the closure of switch 222 so that positive potential is applied
through line 235 to transistor 232 and 248, a common ground for the
circuit being coupled through switch contacts 226 to the wiper of
switch 212, and in the configuration shown in FIG. 9b,ground will
be supplied through conductor 220 to the contact point "B" coupled
to push button switch 202b. When power is applied to the circuit,
the base of transistor 232 goes positive and supplies approximately
11/2 volts on the bus line 228 to all of the switches 204. The
collector of transistor 248 also goes positive supplying plus 10.5
volts to the wiper 208 and through conductor 218 to the contact
terminal 202a. Thus, in the configuration of the circuit shown in
FIG. 9b, the unit provides a11/2 volt trigger signal to all of the
14 contacts; and, through the selector switches 206, 212, anode
voltage of plus 10.5 volts to any one of the contacts, and ground
potential to any other one of the contacts. The indicia herein
given to the various contacts are for the purpose of explanation
and it is equally possible that other numerical systems or
alpha-numerical systems may be adopted for the contacts other than
the "+" and "-" or the other indices herein indicated.
Turning now to FIG. 9a, there is shown a plurality of silicon
controlled rectifiers (SCR), there being 14 in number. Of those 14
SCR's, six are employed for the purpose of providing a false code
signal, seven are employed to establish a six-digit code and a
final SCR is used to control the function of an output indicator.
SCR's 250, 252, 254, 256, 258 and 260 each have their gate
electrodes connected directly to the contact points on the card
herein designated by the index digits "1," "4," "6," "5," "7" and
"+" respectively. These gate electrodes are likewise coupled
through resistors 251, 253, 255, 257, 259, 261 to the card common
ground bus 262 which is in turn coupled to contact point 264
indexed "B." The anodes of SCR's 250-260 are all coupled in
parallel and connected to B+ conductor 266, which is in turn
coupled to contact point 268 herein designated "A." The cathodes of
SCR's 250-260 are coupled in parallel and connected to conductor
270. SCR's 272, 274 and 276 are coupled in series with the anode of
SCR 272 coupled to B+ line 266. The gate electrodes of SCR's 272,
274 and 276 are connected directly to contact points on the card
herein designated by the digits "2", "-" and "8". These gate
electrodes are likewise coupled through resistors 273, 275, 277
respectively to ground bus 278 which is in turn coupled to the
other ground bus 262. Resistors 280, 281 and 282 are coupled
between the cathodes of SCR's 272, 274 and 276 respectively and
ground, to keep each SCR conducting after removal of its respective
trigger signal until the next successive SCR is made
conductive.
Another SCR 282 has its anode coupled to B+ line 266 and its
cathode coupled in series with SCR's 284, 286 and 288. The gate
electrode of SCR 282 is coupled through a resistor 290 to the
cathode of SCR 276. The gate electrodes of SCR's 284, 286 and 288
are connected directly to contact points on the card herein given
the index digits "3," "9" and "0". As with SCR 272, SCR's 284, 286
and 288 are provided with resistors coupled between the gate
electrodes and ground and between their cathodes and ground, with
the exception SCR 288 the cathode of which is coupled to one
terminal of a light emitting diode 290 the other terminal of which
is coupled through resistor 292 to ground. An additional SCR 294 is
connected across the light emitting diode 290, with its anode
coupled to the cathode of SCR 288, and the cathode of SCR 294
coupled to the junction between the diode 290 and resistor 292. The
gate electrode of SCR 294 is coupled through resistor 296 to
conductor 270 and through resistor 298 to ground.
The index digits mentioned herein as assigned to the contact points
on the card are given for illustrative purposes only, it being
understood that the indexing of the card contacts may be done so as
to provide any combination of digits. Here, the first two digits of
the combination are determined by the switches 206 and 212 and the
positions of those switches which provide the utputs to contacts
"A" and "B." With reference to FIG. 9b, it will be indicated that
the positions of those two rotary switches would correspond to
index digits "5" and "3" for letters "A" and "B" respectively. In
this manner, proper connection of those terminals to contacts "A"
and "B" will provide appropriate B+ and ground terminals to
contacts 268 and 264 on the card. The third, fourth and fifth
digits in the code will be represented by index digits "2", "-" and
"8" and the remaining digits in the code number will be determined
by the connections of the gate electrodes of SCR's 284, 286 and
288, here shown to be assigned the digits "3," "9" and "0." Thus,
the combination of the card shown in the drawings is AB2-8390.
When the proper combination of the card is known, and the card is
inserted in the verification unit until all contacts are properly
made, the rotary switches 206 and 212 are moved to the proper
positions, here positions "A" and "B" or "5" and "3" respectively.
Power switch 222 is closed and the verification unit will thereby
provide a positive anode voltage at contact "A" and a ground
connection to contact "B," plus an SCR trigger voltage available at
each push button switch through common bus 228. Anode voltage is
provided to all of the SCR's 250-260, 272 and 283. The trigger
voltage is available to each gate of each SCR through the contacts
except of course the gates to SCR's 283 and 294. The next six
digits of the combination are introduced into the card by pushing
the proper push buttons in the correct sequence, in this case
"2-8390." When push button 2 is depressed, a trigger voltage is
applied to the gate of SCR 272 causing current to flow through the
SCR and through the cathode resistor 280 to ground so that SCR 272
is turned on and maintained in that condition, at the same time
supplying anode voltage to SCR 274. When the dash or minus button
is depressed, SCR 274 will be turned on in a similar manner
supplying anode voltage to SCR 276 which is in turn turned on by
depression of push button corresponding to that number. The
resistors coupled between the gates of the SCR's to ground
desensitize the gates so that they will not trigger the SCR's in
the event there is a stray noise. When SCR 276 is turned on it
turns on automatically SCR 283 thereby enabling SCR 284 and
supplies to the anode of SCR 284 the full anode voltage. It has
been found that due to junction voltage drops occuring between the
anode and cathode of an SCR, where SCRs are cascaded, the voltage
drop is too great if more than three SCR's are coupled in series.
Accordingly the series combination of SCR 272, 274 and 276 is
provided to trigger the intermediate SCR 283 which thereby supplies
full anode voltage to the next successive series of three SCR's.
Then, when push buttons "3," "9" and "0" are depressed, each of the
corresponding SCR's 284, 286 and 288 will fire, each enabling the
following SCR to fire in the same manner. When the "0" push button
is depressed, power is supplied to the light emitting diode 290
which lights to signify that the correct combination has been
introduced in the correct sequence, thereby verifying that the
owner of the card has properly identified himself.
If the proper combination is not known, particularly if the proper
positions for rotary switches 206 and 212 are not known, proper
bias can never be supplied to the card circuit. Even assuming that
those proper positions are known, only SCR 272 can be turned on
even if all of the push buttons are depressed. Assuming that SCR
272 was turned on, then if push button "9," for example, is
depressed, SCR 286 would have no anode voltage and cannot be fired.
Furthermore, the trigger voltage supplied to the gate of SCR 286
will be coupled through the gate resistor to ground and would cause
SCR 272 to turn off. Any other wrong sequence will have the same
effect. The reason that the circuit works in the correct sequence
is that the SCR's, when they have anode voltage, will turn on fast
enough to keep the reviously fired portion of the circuit from
resetting. If any push button other than those numbers which
comprise the correct combination or code sequence are depressed,
the corresponding SCR will fire since SCR 250, for example, will
always have anode voltage and if button "1" is depressed SCR 250
will indeed fire. The output of SCR's 250-260, i.e., their
cathodes, are all coupled through line 270, through resistor 296 to
the gate of SCR 294. If any outputs are obtained from SCR's 250-260
they will trigger SCR 294 on so that current will be shunted across
the diode 290 thereby preventing it from turning on. Therefore,
even if the proper code sequence was used, pushing any one button
corresponding to a number which is not an element of the sequence,
the LED will not light since SCR 294 would be enabled, there being
an available anode voltage to it as soon as an output is obtained
from SCR 288.
It is necessary that the first SCR of the proper code sequence be
immediately enabled and for that reason the anode of 272 is
connected directly to the B+ conductor 266. It would be possible to
determine electrically which is the first digit of the code by
determining which SCR turns on first, and then the next SCR and so
on. But, SCR's 250-260 are provided to give an additional set of
SCR's which can be turned on at any time to further confuse the
investigator. These six SCR's will effectively hide which SCR out
of the group 250-260 and 272 is the correct first digit since any
of them can be turned on first. It will also be noted that any of
the six SCR's 250-260 can be turned on one after the other and by
coupling those SCR's in parallel with essentially no load and all
having anode voltage it has been found that the SCR's will interact
between themselves in random fashion based upon the inherent
internal characteristics of each SCR, its relative location within
the circuit, the number of other SCR's that have been turned on,
etc. In other words, it is possible that all six of the SCR's can
be turned on, but in most cases several will be turned on and then
when a button is depressed to turn on an additional one, it may
reset one or all of the others in a random fashion which makes an
electrical investigation of the circuit extremely confusing.
It will thus be seen that the present invention has provided a
greatly improved method of credit card verification and which will
substantially reduce credit card misuse. While preferred
embodiments of the present invention have been shown and described
herein, it will be obvious to those persons skilled in the art that
changes and modifications might be made and it is, therefore,
contemplated that such changes and modifications are within the
scope of this invention.
* * * * *