U.S. patent number 3,787,714 [Application Number 05/283,846] was granted by the patent office on 1974-01-22 for electronic lock and key systems employing paired key and master coding modules.
This patent grant is currently assigned to SAID Sam L. Resnick, by said Stephen Berens. Invention is credited to Stephen Berens, Sam L. Resnick.
United States Patent |
3,787,714 |
Resnick , et al. |
January 22, 1974 |
ELECTRONIC LOCK AND KEY SYSTEMS EMPLOYING PAIRED KEY AND MASTER
CODING MODULES
Abstract
There is disclosed an electronic key and lock system for
activating an electric latch when a valid key is inserted into a
key receiving receptacle. The system is energized by the insertion
of the key into the receiving receptacle to energize both the key
and a master coding card to cause a correlation sequence to be
implemented to determine whether information contained on the key
is valid by comparing this information with predetermined
information on the master coding card. Various embodiments utilize
key cards having light accommodating apertures operative in
conjunction with photodetectors, key cards having electrical
components operative in conjunction with voltage comparators and
cards employing frequency determining elements.
Inventors: |
Resnick; Sam L. (Bayside,
NY), Berens; Stephen (Peekskill, NY) |
Assignee: |
SAID Sam L. Resnick, by said
Stephen Berens (N/A)
|
Family
ID: |
23087809 |
Appl.
No.: |
05/283,846 |
Filed: |
August 25, 1972 |
Current U.S.
Class: |
361/172; 361/176;
361/182; 361/187; 361/205; 340/5.23; 340/5.65 |
Current CPC
Class: |
G07C
9/00714 (20130101) |
Current International
Class: |
G07C
9/00 (20060101); E05b 049/00 () |
Field of
Search: |
;317/134
;340/147R,147MD,149 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
"Security Lock-Actuating System", IBM Technical Disclosure
Bulletin, Vol. 12, No. 9, Feb. 1970; p. 1473..
|
Primary Examiner: Miller; J. D.
Assistant Examiner: Moose, Jr.; Harry E.
Claims
1. An electronic lock and key system for activating an electric
latch to an opened position to permit entry to a secured area,
comprising:
a. key means having located thereon at least one electrical
component,
b. first means for receiving said key means,
c. second means coupled to said first means and responsive to said
key means being received for generating a plurality of reference
potential levels, one of said levels selected for energizing said
component,
d. means coupled to said first means and responsive to said
energized component for providing a control signal different from
any of said reference potential levels and solely according to the
energization of said component, and
e. comparison means coupled to said latch and responsive to a
different one of said potential levels and said control signal to
activate said latch when said level and said control signal are
within a predetermined range.
2. The electronic lock and key system according to claim 1 further
comprising:
a. auxiliary circuit means capable of being selectively received by
said first means, said auxiliary circuit means including a separate
potential source of a magnitude selected according to said one
potential level for causing said means coupled to said first means
to generate said control
3. Apparatus for activating an electric latch to an opened position
to permit entry to a secured area, comprising:
a. a key receiving receptacle,
b. a key card having located thereon an electrical network, said
key card adapted for insertion into said received receptacle,
c. a master coding card coupled to said receptacle and having at
least one network located thereon, said network arranged according
to said electrical network on said card, to provide a predetermined
control signal when a desired key card is being received by said
receptacle,
d. a selectively activated source of operating potential capable of
providing a plurality of reference potentials when activated,
e. means coupled to said selectively activated source and
responsive to the insertion of said key card into said receptacle
for activating said source,
f. circuit means coupled to said key card and said master coding
card for applying said reference potentials thereto to energize the
same to cause said electrical network on said card to modify one of
said reference potentials, said modified potential being further
modified by said master coding card to provide said control signal,
and
g. actuator means coupled to said latch and responsive to said
control
4. The apparatus according to claim 3 further comprising:
a. auxiliary circuit means capable of being selectively coupled to
said key receiving receptacle, said auxiliary circuit means
including a second source of operating potential of a magnitude
selected acording to one of said reference potentials to cause said
actuator means to operate
5. The apparatus according to claim 4 wherein said key card has
located thereon a plurality of frequency determining components,
each capable of
6. The apparatus according to claim 5 wherein said master coding
card includes a plurality of second frequency determining elements
each one of which is associated with only one of said frequency
determining components on said key card to provide a plurality of
specific frequency control signals when said desired key card is
being received by said receptacle, and means responsive to said
frequencies for generating a single control
7. A locking system of the type for providing an actuation signal
operative to energize an electrical latch to permit access to a
secured area, comprising:
a. a key card having a plurality of terminals areas on an edge
thereof, said card further containing electrical components of a
given value and arranged in a given format on said card,
b. a master coding card having a number of terminals associated
therewith and having located thereon at least one electrical
component selected in accordance with said given value and format
of said component on said key card,
c. terminal receptacle means for selectively receiving said key
card, said terminal means including receptacle means for receiving
said master coding card,
d. reference means coupled to said terminal receptacle means for
providing a plurality of reference potentials for applying to said
key card at least a first one of said potentials to cause said
electrical components on said key card to modify said potential,
said modified potential being applied to said master coding card
and said electrical component for further modification of said
potential to provide a control potential,
e. a comparator having a first and second input terminals and an
output terminal, said first input terminal coupled to said master
coding card and adapted to receive said control potential, said
second input terminal coupled to said reference means for receiving
another of said reference potentials to cause an activation signal
to appear at said output when said control potential is
substantially equal to said another reference potential, and
f. activation means having an input terminal coupled to said output
of said comparator and an output terminal coupled to said latch for
operating the same upon receipt of said activation signal to permit
access to said
8. The system according to claim 7 further comprising:
a. auxiliary circuit means capable of being selectively coupled to
said terminal receptacle means, said auxiliary circuit means
including a separate source of potential of a predetermined
magnitude to energize said key card and said master coding card to
cause said activation means to operate even though there is no
correlation of information on said master coding card.
Description
BACKGROUND OF INVENTION
This invention relates to a lock apparatus and more particularly to
an electronically operated lock and key, capable of accommodating a
number of different control combinations.
Basically the prior art is replete with a great number of patents
directed towards electronic lock and key assemblies. The advantage
of electronic locks over their mechanical counterparts are
relatively obvious in that electronic lock assemblies offer greater
protection in guarding against unauthorized entry, key duplication
or "lock picking."
In recognizing the advantages of using electronics in this art
area, the prior art envisioned various schemes, which essentially
provided a control electronic assembly which operated a solenoid or
electromechanical latch when the correct circuit key was inserted
into the assembly. The control assembly served to implement a
predetermined sequence under control of the key, which sequence if
correct, caused the control unit to activate the latch thus
permitting access to the secured area.
Such control assemblies employ various electrical and magnetic
coding schemes, such as pulses codes, binary codes, selective
frequency determination and so on, to determine correlation between
the predetermined condition and the particular key arrangement.
The major disadvantages of such electronic or magnetic locking
systems resides in the fact that the control units or those units
associated with the door latch exhibit a fixed response
characteristics operated only by a single coded key.
In order to implement a combination so that the door or control
unit can be accessed by other keys, rewiring, component changes and
so on are necessary. Still other prior art systems cannot without
extensive redesign of the systems accommodate a plurality of
different keys simply, reliably and economically.
This particular feature is of prime importance in certain business
activities, such as hotels, motels and so on. In the operation of
such establishments, which cater to guests and in general to the
transient trade, keys are exchanged thousands of times a year. Such
keys are stolen, lost or misplaced, and as such an unauthorized
person possessing such a key would have direct access to the
premises. Due to these factors such establishments suffer huge
losses in regard to stolen property and vandalism.
It would therefore be advantageous to provide a key and lock
assembly which would be difficult to pick, be secure and further
possess the characteristic of being easily changed on a daily or a
more frequent basis. This being necessary to eliminate the problem
of unauthorized access as described above.
BRIEF DESCRIPTION OF PREFERRED EMBODIMENT
A new and improved electronic lock and key system of the type for
providing an actuation signal operative to energize an electric
latch to permit access to a secured area, comprises a key card
having a plurality of terminal areas on an appropriate edge; the
key card further containing predetermined electrical information in
a given format; a master coding card has a number of terminals
associated therewith and has located thereon electrical information
substantially correlated to said information on said key card, said
terminal receptacle means including means for energizing said key
card and said master coding card to cause said respective
information to be compared by providing a comparison signal and
activation means coupled to said latch and responsive to said
comparison signal for operating the latch to permit access to said
secured area only when said information on said key card correlates
with said information on said master coding card.
BRIEF DESCRIPTION OF FIGURES
FIG. 1 is a block diagram showing a secured door and including an
electronic lock and key apparatus according to this invention.
FIG. 2 is a detailed block diagram showing an electronic lock and
key configuration according to this invention.
FIG. 3 is a detailed schematic diagram of an embodiment according
to FIG. 2.
FIG. 4 is a perspective view of a lock and key arrangement
utilizing electro-optical techniques.
FIG. 5 is a partial perspective and block schematic in greater
detail of the embodiment shown in FIG. 4.
FIGS. 6A and 6B show a perspective view of a card and a schematic
diagram of detecting apparatus utilized with the key card.
FIG. 7 is a detailed block diagram of an electronic key and card
assembly using frequency selective principles.
FIG. 8 is a circuit schematic of the apparatus according to FIG.
7.
DETAILED DESCRIPTION OF FIGURES
Referring to FIG. 1, there is shown a door 10 which may be an
enclosure entrance to a room in a motel or hotel or some other
secured area. The door 10 can be opened if the retractable bolt 11
is withdrawn from a locking position (shown dashed) to an opening
position. The retractable bolt 11 may by the plunger of a solenoid
or may be coupled to a suitable electromechanical device as a motor
and so on by means of a mechanical linkage. The function of the
bolt 11 being to provide a first door restraining or locking
position and a second door opening or access position. The
operation of the bolt 11 is under the control of an
electromechanical latch assembly 16, this assembly may contain a
motor and mechanical linkage to afford the desired movement to the
bolt 11.
The electromechanical latch assembly 16 is controlled by means of a
master electronic lock system 17. The system 17, as will be
described in greater detail, contains logic or other circuitry
which performs a predetermined sequence of steps capable of
ascertaining whether an associated key 13 inserted into the slot 14
is valid. If validation is determined, the system 17 operates the
bolt 11 via the latch 16, to withdraw the bolt from the door, thus
permitting entry therethrough.
To implement operation of the bolt 11, a component key receptacle
14 is shown. The receptacle 14 is designed to accommodate a key
card 13, which, as will be explained, has located thereon a circuit
format, capable of causing the master lock system 17 to validate
the card and therefore energize the bolt 11, only for insertion of
the correct key card 13 into slot 14.
Essentially the key card 13 coacts with a terminal board or contact
assembly positioned within key receptacle 14. The terminal or
contact assembly is electrically coupled to the master electronic
lock system 17 by means of wires or otherwise. Also shown located
on a surface of the lock system 17 is a receptacle 18 having a card
accommodating slot 19. Into this slot is inserted a master coding
card 20, which functions as the main validation means for verifying
that a correct key card 13 was inserted into receptacle 14. The
master coding card 20 can therefore be easily removed and replaced
at the whim of the operator of the establishment and can therefore
provide a plurality of different locking combinations solely
dependent upon the nature and characteristics of the master coding
card 20 and its associated key card 13.
In regard to physical location, the electronic lock system 17 is
placed within the confines of the room or area associated with door
10, or at some master location within the building, strictly under
control and access of the operator of the establishment.
In this manner, after a guest checks out, the manager merely
changes the master coding card 20 simultaneous with the preparation
of the room for a new guest. When the new guest arrives, he is
given a new appropriate key card 13, to correlate with the master
coding card 20. In regard to such procedures, it can be seen that
keys or key cards can be supplied to guests on a random basis and
the same key card need not ever be used to activate the same
locking mechanism associated with a particular door. While, of
course, the utility of such arrangements have been described in
conjunction with motel and hotel security, it will be apparent that
various other establishments and systems would also require the
apparatus to be more fully described.
Referring to FIG. 2, there is shown a detailed block diagram of a
key card assembly (as 13 of FIG. 1), a master electronic lock
system (as 17 of FIG. 1) incorporating a master coding card (as 20
of FIG. 1).
As shown in FIG. 2, the key card 13 may include a component network
21, which network includes one or more electrical components as
resistors, capacitors, inductors and so on. The key card 13 has
located on an edge thereof a plurality of terminals designated as
22 through 35 respectively. It is understood that the exact number
of terminals are not important as more or less could be employed.
It is, however, noted that the component network does not
necessarily interface or couple to all the existing terminals 22 to
35 as located on the card assembly 13.
The terminal assembly of card 13 is adapted to coact with the card
accommodating receptacle (14 of FIG. 1) which as previously
explained is located and associated with the master electronic lock
system. The receptacle 14 has a corresponding terminal for each
terminal 22 to 35 located on card 13.
There is also shown a switch 36, which has a moveable plunger or
actuator arm 37. The function of the switch is to supply power to
the lock system only upon insertion of the key card 13 into the
card accommodating receptacle 14.
For example, as is schematically shown in FIG. 2, one conductor 38
of the AC lines 38 and 41 (120 volts, 60 Hz or other) is directed
through switch 36, which is normally opened. As the card 13 is
inserted, the edge of the card 13 activates the plunger 37 causing
AC to be applied to the power supply module 40. Therefore, as long
as a card 13 is coacting with receptacle 14 switch 36 is operated
to supply prime (AC) power to power supply 40.
As can be seen, lines 42, 43 and 44 emanate from the power supply
40 and are coupled to appropriate terminals of receptacle 14, which
is in this instance corresponds with terminals 29, 30 and 31 of key
card 13. The circuit components contained in network 21 (as
resistors) therefore respond to these applied voltages and the
altered voltages due to the action of the network are in turn
applied to contacts 23 through 28. It is seen that once the card 13
is inserted into receptacle 14, the contacts 23 through 28 are
directly wired to another receptacle or terminal assembly 18 and
thereby directly interface with terminals 45 to 50. Terminal 22 is
directed via the receptacle 14 directly to the electric latch 52,
to therefore assure that operating potential is available at the
latch 52 when a card is inserted.
The master coding card 53 (20 of FIG. 1) is inserted into
receptacle 18 and has terminals thereon which directly interface
with terminals 45 to 50 of receptacle 18, and therefore terminals
23 to 28 of card 13.
Briefly, but as will be explained in greater detail, the master
coding card 53 is matched to the key card 13 and is arranged to
process the altered voltages developed by the component network 21
to predetermined voltages at the output terminals 54 and 55 of the
master coding card 53. These predetermined voltages are applied to
voltage comparator circuits 56. The comparators 56 also receive
standard comparision voltages from the potentiometer module 59.
Module 59 contains a number of variable elements which are
energized by lines 57 and 58 emanating from the main power supply
module 40. The potentiometers are used to establish reference
voltages for the comparators 56. These reference voltages are
compared with the master coding card processed levels, and if they
compare within predetermined tolerances, the comparators 56 will
supply an activating signal to NOR gate 62. Gate 62 in turn
triggers a silicon controlled rectifier or SCR 64, which in turn
activates the electric latch 52 and the associated bolt to the door
opened position.
This therefore releases the bolt and permits entry to the room via
door 10 of FIG. 1.
As can be seen, power is supplied by means of power supply 40 to
the entire unit, i.e., comparators 56, key card 13, master coding
card 53 and so on. Therefore, without further structure, a power
failure would cause the entire lock system to become
inoperative.
The unit contains a series of auxiliary voltage dividers 66 which
have inputs coupled to receptacle 14 at those terminals
corresponding to the unused terminals 32, 33, 34 and 35 of key card
13.
These terminals are associated with a special key card 13 for use
only during such a powerful failure by the management or authorized
personnel.
The special key card contains a source of power as a battery. When
the special card is inserted, the battery energizes the auxiliary
voltage dividers 66, the auxiliary comparators 67, the auxiliary
NOR gate 68 and the auxiliary SCR 69.
The auxiliary SCR 69 is also coupled to the electric latch 52, to
activate the same and therefore release the bolt.
This structure specifies operation during power failure and enables
supervisory personnel to gain access to the enclosure or room
protected by the lock system. It is also noted that the special key
and associated auxiliary circuit arrangements enable operation of
the lock if there is a component failure in the main assembly, such
as a failure of NOR gate 62 and so on.
This, of course, provides redundancy and enables back-up operation
for such contingencies.
Referring to FIG. 3, there is shown a more detailed schematic
diagram of a locking system according to this invention. Numeral 71
references a key card which employs a series of resistor networks
located on the surface thereof. Alternatively, key card 71 can
employ integrated circuit techniques wherein the resistor would be
imbedded in the card or diffused. The resistors such as 72 and 73
form a voltage divider network. The junction between resistors 72
and 73 is coupled to a separate terminal on connector 78 which
connector performs a similar function as connector 14 of FIG. 2. An
additional resistor 74 is also shown, as is another voltage divider
comprising resistors 74, 75, 76 and 77. It is seen that the
junction between resistors 76 and 77 is also coupled to a separate
terminal which is associated with an appropriate terminal on
connector 78. There is also shown the power supply activating
switch 80 having a movable plunger 79 which serves to couple power
to power supply 81 upon activation of the switch 80. It is also
understood that while resistors are shown employed upon the key
card 71 other components and combinations such as capacitors,
semiconductors and so on could be utilized as well. The resistors
as 72 to 77 as contained upon the card are oriented in a desired
sequence which sequence has been predetermined and preset.
When the key card 71 is inserted in the receptacle 78, the power
supply 81 is thus activated and operating voltages (schematically
designated as +V, V3 and V4) are applied to the key card via
receptacle 78. The voltage dividers comprising the resistors 72 to
77 modify these voltages according to their predetermined voltage
division ratios. The action of the voltage dividers cause
predetermined fixed voltages to be applied to lines 87 and 88 which
lines are associated with and are contained upon the master key
card 85. The output lines 87 and 88 coact with appropriate mating
lines 89 and 90. It is first noted that resistors 83 and 84 on the
master coding card 85 further modify the voltages before
application to the dual comparator circuits 91 and 92. The
comparators also have resistors in conjunction with their inputs as
designated by numerals 89 and 90 which resistors further modify the
voltages applied to the appropriate terminals. In this instance,
the application of the voltages from the key card 71 and thence
from the master coding card 85 are applied to the inputs of the
comparators 91 and 92. The function of dual comparators 91 and 92
and circuits for such devices are well known in the art. Such dual
comparators can be purchased as operational amplifiers or other
suitable integrated circuit devices. The dual voltage comparators
91 and 92 also receive reference voltage inputs to their alternate
inverting and non-inverting inputs designated as 93 and 94 from two
potentiometers 95 and 96. The potentiometers receive operating
potential designated as V1 and V2 from power supply 81. The dual
voltage comparators 91 and 92 operate as follows: If the voltages
applied to the dual comparators equal the reference voltages
supplied by potentiometers 95 and 96, the comparators will supply a
near zero or ground output voltage. If both voltages from both dual
comparators 91 and 92 are at a low value, the output of gate 97
goes high. This high voltage enables the SCR 98. The anode of SCR
98 is coupled through a coil 99 which is the activation coil of the
electric latch or solenoid device. This device directly operates
the bolt as associated with the secured door. It is also shown that
one terminal of the coil 99 goes directly to a terminal on
connector 78 which terminal receives power from power supply 81 via
the key card 71 by means of the energizing line 82. Thus, if the
voltages at the inputs of the comparators correlate with the
voltages supplied by the reference source, the SCR 98 will trigger
and remain energized until the key card 71 is removed from the
receptacle 78.
FIG. 4 shows an alternate embodiment of a key card and a coding
card arrangement. The embodiment of FIG. 4 uses light sensitive
devices. In this particular arrangement, a key card 100 is
fabricated from a thin plastic or other type of material. On the
surface of the material 100 then exists a number of different
locations for different degrees of transparency. For example, the
key card 100 may exactly consist of a film negative having certain
areas which are light transmitting and other areas which are
opaque. In a similar manner, the card 100 may be an opaque piece of
plastic with holes punched or apertures located on the surface at
predetermined locations. The card 100 is inserted into a slot as
shown in the Figure. Insertion of the card activates a light source
102. The light source typically emits a uniform area light which is
directed at the card 100. For example, at the transparent area of
the card, light will shine through or pass through and impinge upon
the surface of a bank of photo cells which are contained in module
105. These photo cells typically designated as 104 through 120
respond to the intensity of the light allowed to propogate through
the card 100. Typically, a photo cell will decrease its resistive
value upon illumination. As indicated in conjunction with FIG. 3,
this change in resistance can alter the character of a voltage
device or other circuit element in a predetermined manner. The bank
of photo cells 105 is coupled to a connector 121. Also coupled to
connector 121 there is shown a master coding card 124 which is
inserted into a module 123. This master coding card as previously
indicated is matched to the electronic key card 100 and supplies
suitable information to indicate to circuit components, such as
comparators, that correlation has been made and the correct card
100 has been inserted. This would therefore cause the unlocking of
the door by means of an electromechanical device as previously
indicated.
Referring to FIG. 5, a more detailed schematic of a light sensitive
key and lock configuration is shown. The light source 102 has a
mirror surface 126 as a backing thereof. The light source employed
can be conventional bulbs, neon devices or light emitting diodes.
The mirror surface 126 serves to reflect light from the source
towards a plurality of photosensitive devices mounted in a detector
module 103. There is shown a key card 100 having a plurality of
light emitting apertures located on the surface thereof. The key
card 100 may be selectively inserted between the light source 102
and the photodetector module 103. Upon insertion of the key card
102 into an appropriate slot, the plunger 127 of switch 128 is
depressed which serves to supply power to the power supply module
129. The operation of the switch 128 operates the light source and
the detector circuitry. The detector circuit 103 may employ a
plurality of light detecting devices 132 to 140. These devices may
be photocells or photo-sensitive resistors and as they are
selectively illuminated due to the particular card format, their
currents or voltages vary depending upon the circuit configuration
they are included in. These photocell currents, as determined by
the light intensity, are applied to the master coding card 124 via
the connector assemblies 132 and 141. The master coding card 124
may comprise a series of wire connections or circuit elements that
are picked according to the particular format of the key card 100.
In this manner, as indicated previously, the coding card 124 and
the key card 100 are matched. Therefore, if one desired to change
the operation of the lock associated with any particular door, one
merely would change the key card 100 and the master coding card
124. The master coding card interfaces with a series of logic gates
144. These gates are set up in a typical decoder circuit to assure
correlation between the coding card connections and the key card to
thereby activate the SCR 145 when a proper match is afforded.
Activation of the SCR 145 serves to operate the electric latch 146
thus providing admittance to a particular secured location.
FIG. 6 shows a more detailed arrangement for a light sensitive lock
assembly. FIG. 6A shows a typical card 148. The card 148, for
purposes of this example, has three apertures 149, 150 and 151
located on a surface thereof. As indicated, the card may be
fabricated from an opaque or non-light conducting plastic or other
material. The apertures or holes may be punched or otherwise formed
on the surface of the card. FIG. 6B shows a bank of photocells
arranged in a rectangular matrix configuration. The photocells are
numbered respectively as 152 through 160. It is immediately seen
that as the card 148 is placed in front of these photocells and a
source of light directed in front of the card, only certain of the
photocells would be subjected to light. The other cells would not
be exposed to light due to the fact that they would be blocked by
the opaque portions of card 148. For example, for a particular
configuration shown, only photocells 154, 155 and 159 would be
illuminated. The resistance of these cells would decrease
substantially while the resistance of the remaining cells would
remain at a high value. Each photocell in the bank receives an
operating voltage from a power supply (not shown). This operating
voltage causes currents to flow through the photocells. The value
of these currents depends upon whether or not the photocell is
being illuminated and the degree of illumination. Each photocell
has a ground return afforded through an associated resistor 161 to
169. As a photocell is being illuminated, then its resistance value
is lowered causing a large voltage to appear across the associated
resistor. The outputs of this circuit are taken from the resistors
161 to 169 and are applied to the connector 170 and thence to
connector 171. A master coding card 172 contains a series of
invertors or amplifiers 173 to 178. There is one amplifier for each
photocell. The photocells that are illuminated provide a high
voltage at the input of these amplifiers, which high voltage is
inverted to a low voltage at the output of the amplifiers. In the
above example, the photocells 154, 155 and 159 are illuminated.
Amplifiers 174, 176 and 177 then provide a low voltage at their
outputs. The low voltages cause the gates 179, 180 and 181 to
change logical states. The outputs of these gates 179 through 181
are coupled directly to gate 182. Therefore, gate 182 has three
simultaneous inputs all at the high level. Gate 182 then proceeds
to triger the SCR 183. The SCR 183 is in series with a coil 182
associated with the electromechanical latch and therefore this
latch is energized and thus causes the secured door or area to open
by moving a bolt to the door-opened position.
Thus far there has been shown a key card which includes electrical
components as resistors and operated to alter the voltage or
current. There has also been shown a key card and lock assembly
which uses light sensitive devices and operates with a resistor
change to thereby afford a voltage or current change. It is also
obvious to one skilled in the art that many additional components
and circuits may also be used in lieu of those shown above without
departing from the scope and concept of this invention.
For example, now referring to FIG. 7 there is shown an electronic
key and lock assembly which operates on the basis of comparing
frequency. A key card 186 contains a component network 187.
Associated with the card 186 are electrical contacts 189 to 192
adapted to coact with a key card accommodating receptacle 188. The
receptacle 188, as previously described, coacts with the receptacle
206. The receptacle 206 is adapted to receive the master coding
card 207 and has its output coupled to an oscillator circuit card
207. The output of the oscillator circuit card is applied to a
frequency selective card 208. The output of the circuit card 208 is
applied to level converter card 209 which is coupled to an AND gate
210. The output of the AND gate 210 is coupled to a SCR 211 which
is in series with an electric latch 212 adapted to operate a
solenoid or other device to allow the opening of a door. The
circuit shown in FIG. 7 also includes auxiliary voltage dividers
and comparators 214 and 215 as well as an auxiliary gate 216 and
SCR 217 to enable operation of the lock during a power failure or a
component failure. This operation, as has been previously
described, is afforded by means of a special key card which the
operator can insert into receptacle 188 and which key card is
especially adapted to coact with terminals 199 to 202 of receptacle
188. This feature provides power failure operation as well as
operation in the case of a component failure.
Referring to FIG. 8 a detailed schematic of a frequency selective
circuitry particularly as shown in FIG. 9 is presented. The key
card 218 is shown (as 186 of FIG. 7) including a number of circuit
components and a piezo-electric or quartz crystal 224. Such
crystals are capable of producing very precise frequency signals
upon activation of such crystals in a suitable circuit. Also shown
on card 218 are additional components including capacitors 222 and
223 and a number of resistors 219 to 221. The key card 218 has a
series of terminals on a suitable edge which is designed to coact
with receptacle 225. Upon insertion of the card 218 into receptacle
225, power is applied to the system as previously described via
switch 227. There is shown coupled to the terminal assembly 225
first and second transistors 228 and 234. The transistor 228 has an
emitter electrode coupled to the base of a transistor 233. The
transistors 228 and 233 form a parallel T oscillator configuration.
The frequency of this oscillator is determined by resistors 219,
220 and 221 and capacitor 222. Transistor 235 is arranged in a
crystal oscillator configuration employing feedback from collector
to base through the crystal 224. This oscillator configuration is
sometimes referred to as a Pierce oscillator. The frequency of the
parallel T oscillator is in part determined by the components,
resistor 221 and capacitor 222; however, the additional components
such as 241 to 246, which is a T circuit configuration, appear on
the master coding card 240. In this manner, the exact frequency of
the oscillator is determined in part by the key card and in part by
the master coding card. Both the frequency of the parallel T
oscillator and the crystal oscillator are applied via terminals 246
and 247 associated with the master coding card receptacle 239 to
operational amplifier circuits 252 and 253 arranged as active
bandpass filters. The exact format and structure as well as circuit
design of such bandpass filters using operational amplifiers are
well known in the art. The active bandpass filters circuits are
responsive to the frequency of the parallel T oscillator and the
crystal oscillator, the components which determine the most
sensitive response of the active bandpass filters are also located
on the master coding card 240. These components include resistors
254, 255 and capitor 256 and 257 for the parallel T oscillator in
regard to the active bandpass amplifier 253. The active bandpass
response for the crystal oscillator is also determined by
components on the master coding card 240 including resistors 258,
259 and capacitor 261. It is noted that the insertion of the
various cards into the associated receptacles assures proper
circuit configuration to enable efficient oscillator and bandpass
filter operations. The outputs of the bandpass filters 252 and 253
are modified by means of the voltage dividers and potentiometers.
These outputs are coupled to the appropriate inputs of an AND gate
266. The AND gate provides a positive output when the frequencies
are correct which output triggers SCR 272 and activates the coil
270 associated with an electric latch. This therefore enables one
to gain access to the secured area.
While the specification has been illustrated in terms of passive
key card, it is obvious that key cards could include active devices
as transistors and so on to accomplish the results contained
herein. It is also noted that the concept described can provide a
number of different combinations for any lock having the structure
depicted herein and that each and every combination can be
correlated between a matching key card and master coding card which
cards can be changed quickly and inexpensively at the whim of an
operator. Since various modifications will become obvious to those
skilled in the art, such modifications are determined to be within
the actual scope and breadth of this invention as further defined
in the following claims.
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