U.S. patent number 3,651,464 [Application Number 05/117,271] was granted by the patent office on 1972-03-21 for high security electrical key.
This patent grant is currently assigned to Eaton Yale & Towne Inc.. Invention is credited to Robert H. Du Quesnay, Robert A. Hedin.
United States Patent |
3,651,464 |
Hedin , et al. |
March 21, 1972 |
HIGH SECURITY ELECTRICAL KEY
Abstract
A key for use with an electrical security system includes a
plurality of contacts for conveying a binary coded permutation of
electric signals to key receiving means of the system for actuating
the system when the key is the proper key, a plurality of conductor
paths for interconnecting at least a portion of the plurality of
contacts, and control means associated with the conductor paths for
controlling the conductivity therethrough. The control means has a
first condition when the key is engaged with the key receiving
means and second condition when the contacts are disengaged from
the key receiving means. When the control means is in its first
condition the contacts convey the predetermined binary coded
permutation to the key receiving means so as to actuate the
security system and when the control means is in its second
condition the contacts are inoperable to convey the predetermined
code stored on the key. Accordingly, deciphering of the key by an
unauthorized person is prevented when the key is disengaged from
the key receiving means and the control means is in its second
condition.
Inventors: |
Hedin; Robert A. (Yorba Linda,
CA), Du Quesnay; Robert H. (Buena Park, CA) |
Assignee: |
Eaton Yale & Towne Inc.
(Cleveland, OH)
|
Family
ID: |
22371937 |
Appl.
No.: |
05/117,271 |
Filed: |
February 22, 1971 |
Current U.S.
Class: |
235/487;
361/172 |
Current CPC
Class: |
G07C
9/00182 (20130101); G07C 2009/00761 (20130101) |
Current International
Class: |
G07C
9/00 (20060101); H04q 009/00 (); G05b 001/00 ();
H01h 047/00 () |
Field of
Search: |
;340/149,150,151 ;200/46
;235/61.11,61.11A,61.12 ;317/134 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yusko; Donald J.
Claims
What we claim is:
1. A key for actuating a security system having key receiving
means, said key comprising a body member, a plurality of contacts
mounted on said body member for conveying a binary coded
permutation of signals to the key receiving means, a plurality of
conductor paths each of which interconnects at least two of said
plurality of contacts to enable said contacts to convey a binary
coded permutation of signals to the key receiving means of the
security system, and control means disposed in said plurality of
conductor paths for controlling the conductivity of said plurality
of conductor paths, said control means having a first condition
wherein the conductor paths conduct in a predetermined manner and
said contacts convey said binary coded permutation of signals to
the key receiving means and a second condition in which said
conductor paths are prevented from conducting in said predetermined
manner and said contacts are inoperable to convey said binary coded
permutation of signals.
2. A key for actuating a security system as defined in claim 1
wherein said control means is operable to render at least one of
said conductive paths, which is disposed between at least a first
and second one of said contacts, conductive when said control means
is in one of said first and second conditions and nonconductive
when said control means is in the other of said first and second
conditions, said first one of said contacts being operable to
convey a 1 bit of information when said conductive path is
conductive and a 0 bit of information when said conductive path is
non-conductive, said bits of information forming a part of said
binary coded permutation of signals.
3. A key for actuating a security system as defined in claim 2
wherein said second one of said contacts is a power receiving
contact operable to have a potential applied thereto upon
engagement of said power receiving contact with the key receiving
means, said power receiving contact transmitting said potential to
said control means to thereby actuate said control means to said
first condition.
4. A key for actuating a security system as defined in claim 1
further including a power receiving contact operable to have a
potential applied thereto upon engagement with said key receiving
means and wherein at least one of said plurality of contacts is
operable to apply a potential to the key receiving means upon
engagement therewith when said control means is in said first
condition, said power receiving contact directing said potential to
said control means to thereby actuate said control means to said
first condition to control the potential applied by said one
contact to the key receiving means.
5. A key for actuating a security system as defined in claim 4
wherein a second one of said plurality of contacts is operable to
have a potential applied thereto upon engagement with the key
receiving means and a third one of said plurality of contacts is
operable to apply a potential to the key receiving means upon
engagement therewith, said second contact directing said potential
to said control means to thereby control the potential applied by
said third contact to the key receiving means, said second contact
having no potential applied thereto when said third contact is
utilized to convey a 0 bit of information to the key receiving
means to actuate a security system with one predetermined binary
coded permutation and said second contact having a potential
applied thereto to enable said third contact to direct a 1 bit of
information to the key receiving means to effect actuation of a
security system by another predetermined binary coded
permutation.
6. A key for actuating a security system as defined in claim 1
further including a power receiving contact operable to have a
potential applied thereto upon engagement with the key receiving
means and wherein said control means includes switch means disposed
in at least one of said plurality of conductor paths for
controlling the conductivity therethrough, said power receiving
contact being connected with said switch means, said switch means
having a conductive condition when a potential is applied thereto
by said power receiving contact and said power receiving contact is
engaged with the key receiving means and a nonconductive condition
when said power receiving contacts are disengaged from the key
receiving means.
7. A key for actuating a security system as defined in claim 6
wherein said switch means includes a transistor having its base,
collector, and emitter connected to first and second ones of said
plurality of contacts and to said power receiving contact, said
transistor having a nonconductive state when said plurality of
contacts and power receiving contact are disengaged from the key
receiving means and a conductive state when said plurality of
contacts and said power receiving contact engage with the key
receiving means and a predetermined potential is applied to said
first and second of said plurality of contacts and to said power
receiving contact, said transistor when in said conductive state
enabling said plurality of contacts to convey said binary coded
permutation of signals to the key receiving means.
8. A key for actuating a security system having a plurality of
contacts some of which receive information from said key and at
least one of which is a power contact for applying a potential to
said key, said key comprising a body member, a plurality of spaced
apart key contacts mounted on said body member, each of said
plurality of key contacts having a first end portion and a second
end portion that is engageable with the plurality of contacts of
the security system for conveying information to the security
system to effect actuation thereof, a power receiving contact
engageable with the power contact of the security system for
directing a potential to at least one of said plurality of key
contacts, and control means mounted on said body member
interconnecting said first end portions of at least a portion of
said plurality of key contacts, said control means having a first
condition when said key contacts engage with the plurality of
contacts of the security system and said power receiving contact
engages with the power contact and a second condition when said key
contacts are disengaged from the plurality of contacts of the
security system, said control means when in said first condition
interconnecting said key contacts in a predetermined manner to
enable said key contacts to direct a predetermined code to the
plurality of contacts of the security system, said control means
when in said second condition interconnecting said key contacts in
a second predetermined manner to prevent said key contacts from
conveying said predetermined code.
9. A key for actuating a security system as defined in claim 8
wherein said predetermined code directed to the security system
when said control means is in said first condition is a binary
coded permutation, said binary coded permutation including 0 and 1
bits of information, each of said plurality of key contacts being
operable to convey a 1 bit of information when said key contacts
receive a potential applied thereto from said power receiving
contact and a 0 bit of information when said key contacts are
prevented from having a potential applied thereto by said power
receiving contact, said control means when in said first condition
enabling at least one of said key contacts to have a potential
applied thereto by said power receiving contact and when in said
second condition preventing a potential from being applied from
said power receiving contact to said one key contact.
10. A key for actuating a security system as defined in claim 8
wherein said power receiving contact is connected to said control
means, said power receiving contact upon the application of a
potential thereto by the power contact actuating said control means
to said first condition.
11. A key for actuating a security system as defined in claim 10
wherein said power receiving contact directs said potential to said
control means to thereby control the potential applied by other of
said key contacts to the plurality of contacts of the security
system.
12. A key for actuating a security system as defined in claim 8
further including a power receiving contact operable to have a
potential applied thereto upon engagement with the key receiving
means, and wherein said control means includes switch means
disposed in at least one of said plurality of conductor paths for
controlling the conductivity therethrough, said power receiving
contact being connected with said switch means, said switch means
having a conductive condition when a potential is applied thereto
by said power receiving contact and said power receiving contact is
engaged with the key receiving means and a nonconductive condition
when said power receiving contact is disengaged from the key
receiving means.
13. A key for actuating a security system as defined in claim 12
wherein said predetermined code is a binary coded permutation of
signals that said key contacts direct to the plurality of contacts
of the security system, said binary coded permutation of signals
being controlled by the conduction and non-conduction effected by
said control means between said power receiving contact and said
plurality of key contacts, each of said key contacts conveying a 1
bit of information when said control means effects conduction
between said key contact and said power receiving contact and a o
bit of information when said control means prevents conduction
between said key contact and said power receiving contact.
14. In a key for applying a particular binary coded permutation of
electric signals to an electric security system and having a
plurality of contacts through which the signals are applied to the
system, said particular permutation comprising a normal code of the
key, circuit means interconnecting contacts of said plurality of
contacts on the key, control means forming a part of said circuit
means and changing state when potential is applied through a
certain combination of said contacts to the circuit through
portions of said circuit means through which said potential will
act when said control means are in a changed state to establish
said particular permutation of signals the said plurality of
contacts, and the establishing of said signal permutation through
said control means circuit portions being dependent upon the
changed state of the control means so that said control means will
withhold the normal key code when a potential is applied through a
contact combination that differs from said certain combination.
15. A key for applying a particular binary coded permutation of
electric signals to an electric security system as defined in claim
14 in which said circuit means include portions whereby said
control means make one contact of said plurality of contacts
relatively conductive and nonconductive so as to offer alternately
a 1 bit signal or a 0 bit signal.
16. A key for applying a particular binary coded permutation of
electric signals to an electric security system as defined in claim
14 in which said circuit means include a portion that causes said
control means to change state in response to a potential applied
through a further contact of said plurality of contacts.
17. A key for applying a particular binary coded permutation of
electric signals to an electric security system as defined in claim
14 in which said circuit means include resistive elements offering
a limited degree of conductivity between contacts of said plurality
of contacts.
Description
The present invention relates to a key for controlling electric
locks and security systems, and more specifically to a key having
binary coded information stored thereon and means for preventing
deciphering of the coded information stored on the key.
Keys that utilize open and closed electrical circuits to convey a
binary coded permutation to a lock or security system are known in
the art. One such key is disclosed in the Hedin and Balzano U.S.
Pat. Re. No. 27,013, issued Dec. 22, 1970. The Hedin and Balzano
patent discloses a key having a plurality of contact members
engageable with contacts of a lock or security system. Certain of
the contact members are in a closed circuit and others are in an
open circuit so that a binary code may be applied to the lock
system to effect actuation thereof. Another known key utilizing a
binary coded permutation to operate a security system is disclosed
in the Hedin application entitled "Keys for Electronic Security
Apparatus," Ser. No. 23,272, Filed Mar. 27, 1970, which discloses a
key that may be termed a memory key. The memory key, unlike the key
disclosed herein, need have no permanent code but is equipped with
memory elements that will retain different codes that may be
impressed upon them. The key disclosed herein will permanently
retain a particular code that will be the normal code of the key,
and will offer a different code only when put to improper use.
While the binary coded keys of the prior art offer security that is
satisfactory for many purposes, it is possible to utilize
procedures that will decipher the keys and there is need for a key
that will offer the best security.
Accordingly, an object of the present invention is to provide a new
and improved key for actuating a security system which has means
therein to prevent the deciphering of the code stored on the
key.
Another object of the present invention is to provide a new and
improved key for actuating a security system which has key
receiving means, the key including a plurality of contacts, a
plurality of conductor paths interconnecting at least a portion of
the plurality of contacts and means located in the plurality of
conductor paths for controlling the conductivity of the paths, and
wherein the means for controlling the conductivity has a first
condition which enables the contacts to convey binary coded
permutation to the key receiving means and a second condition in
which the contacts are inoperable to convey the binary coded
permutation.
Still another object of the present invention is to provide a new
and improved key for actuating a security system, the key having a
plurality of contacts some of which receive information from the
key and at least one of which is a power contact for applying power
to the key, the key including a plurality of key contacts for
conveying information to the contacts of the security system, a
power receiving contact engageable with the power contact of the
security system and through which power will be directed to at
least one of the plurality of key contacts, and means
interconnecting at least a portion of the plurality of key contacts
and having a first condition when said key contacts engage with the
plurality of contacts of the security system, the power receiving
contact then engaging with the power contact, to interconnect the
key contacts in a predetermined manner to enable the key contact to
direct a predetermined code to the contacts of the security system,
and a second condition effective when the key contacts are
disengaged from the plurality of contacts of the security system to
prevent the key contacts from conveying the predetermined code.
A further object of the present invention is to provide a new and
improved key for actuating a security system having key receiving
means, including a plurality of contacts for conveying a
predetermined binary coded permutation to the key receiving means
to actuate the security system, a plurality of conductor paths
interconnecting at least a portion of the plurality of contacts,
and control means having a first condition enabling the contacts to
convey the predetermined binary coded permutation to the key
receiving means and a second condition disguising the predetermined
binary coded permutation when the contacts are not engaged with the
key receiving means, and wherein the control means when in its
second condition enables the contacts to convey a plurality of
binary coded permutations to thereby prevent deciphering of said
predetermined binary coded permutation.
Further objects and advantages of the present invention will become
apparent from the following detailed description thereof taken in
conjunction with the following drawings wherein:
FIG. 1 is a perspective view of a key embodying the present
invention; and
FIG. 2 illustrates schematically the circuitry of the key and the
security system.
A binary coded key 10 having a body member 12 and a plurality of
contacts 14, 16, 18, 20, 22, 24, 26, 28, 30, and 32 is illustrated
in FIG. 1 and 2. The key 10 is operable to be engaged with a key
receiving means of a security system which controls access to a
secured area. The security system is schematically illustrated as
including key receiving means and coded circuit 34 and a lock 36
which is controlled by the circuitry 34. The key receiving means
and coded circuits may be in a preferred embodiment similar to the
circuitry disclosed in the Hedin and Balzano patent already
referred to U.S. Pat. Re. No. 27,013 entitled "Key Actuated
Electronic Security System," issued Dec. 22, 1970. As is described
in the Hedin and Balzano patent the key receiving means is operable
to receive information stored on the key 10 upon engagement
therewith. The key receiving means directs the information to the
coded circuits and if the information directed to the coded
circuits is correct, i.e., a correct code, the coded circuits
effect operation of the lock 36 to provide for access to the
secured area.
The key receiving means includes a plurality of contacts 14a, 16a,
18a, 20a, 22a, 24a, 26a, 28a, 30a, and 32a which are operable to
engage with the contacts 14-32 respectively of the key 10 upon
insertion of the key 10 into the key receiving means. The key 10
will then be operable to convey a binary code via the key receiving
means to the code circuitry. If the binary code is a proper code
the controlled lock 36 will be actuated and entry to the secured
area may be effected as is described in the aforementioned patent.
A particular code is assumed simply for the purpose of describing
the invention, and that code is indicated in FIG. 2 by a group of
"0" and "1" information bits C contained in the coded circuits 34,
and by corresponding bits CK contained in the key.
The contacts 14-30 disposed on the body 12 of the key 10 are
operable to form either closed or open circuits with the contact 32
which is a power contact. The contact 32 is operable to be engaged
with the contact 32a of the key receiving means which is associated
with a power supply, schematically illustrated in FIG. 2, to
thereby apply power to the contact 32 upon insertion of the key 10
into the key receiving means. If a closed circuit is completed
between the contact 32 and one of the other contacts, a potential
will be applied to the one contact and the contact will convey to
the key receiving means a 1 bit of information. If an open circuit
is formed between the contact 32 and one of the other contacts, the
one contact will convey a o bit of information to the key receiving
means. As is schematically illustrated in FIG. 2 the contacts 14-30
form open and closed circuits with the contact 32 to convey
information in the form of binary bits to the coded circuits and
key receiving means 34. The contacts 14, 18, 20, 22 and 28 are
operable in the present embodiment of the invention to convey 1
bits of information to the key receiving means and coded circuits
34. The 0 and 1 bits of information form a binary coded permutation
which is utilized to actuate the lock 36. It should be appreciated
that while specific bits of information are illustrated associated
with specific contacts these may be easily varied to form a variety
of codes.
In the form that has been chosen to illustrate, the key contacts
18, 22, 28 and 30 merely utilize an earlier development shown in
the application of R. A. Hedin, Ser. No. 27,686, filed Apr. 13,
1970, entitled "Method and Apparatus for Producing Encoded
Electrical Keys." Thus, when the key 10 is engaged in the key
receiving means, power will be transmitted via the contact 32 to a
bus bar 40 located on the upper portion of the body member 12. The
bus bar 40 will then apply a potential directly to the contacts 18,
22, and 28 via the conductive portions 42, 44 and 46 disposed
between the bus bar 40 and the contacts 18, 22, and 28,
respectively. Thus, the contacts 18, 22 and 28 will convey 1 bits
of information to the key receiving means via the conductive
portions disposed between the bus bar 40 and the contacts. The
contact 30 may have been formed with a conductive portion
connecting it with bus bar 40, but that portion has been removed
and therefore no potential will be applied thereto and thus the
contact 30 will convey a 0 bit of information to the key receiving
means. By utilizing the earlier Hedin development mentioned above,
the owner of the key may remove any of the conductive portions 42,
44, 46 so as to make limited changes in the code, enabling him to
establish a code that is unknown to the manufacturer of the
key.
Supplying power to the power contact 32 also effects energization
of control means 38 disposed in the upper portion of the key body
12. The control means 38 is associated with circuitry which
provides conductor paths between certain of the contacts so that
either 0 or 1 bits of information can be conveyed by the contacts
associated with the control means 38. The control means 38 is
energized via the line 48 which is connected to the upper portion
of the contact 32. Energization of the control means 38 will enable
the contacts 14 and 20 to convey 1 bits of information to the key
receiving means and the contacts 16, 24 and 26 to convey 0 bits of
information to the key receiving means.
The control circuitry 38 includes a PNP transistor 50, and a pair
of NPN transistors 52 and 54. A resistor 56 is connected to the
base of the transistor 50, and resistors 58 and 60 are connected to
the bases of the transistors 52 and 54 respectively. The potential
applied to the line 48 will bias the base of transistor 52 through
the resistor 58 and the base of the transistor 54 through a line 62
and the resistor 60. The potential on line 48 will also be applied
through the conductor 62 to the emitter of the transistor 50. The
base of the transistor 50 is connected through the resistor 56 and
a lead 64 to contact 16. When contact 16 engages with the contact
16a of the key receiving means, there will be a difference of
potential in effect grounding the base of transistor 50, as
represented schematically by ground 66 connected to contact 16a of
the key receiving means. Since the base of transistor 50 is
grounded and a positive potential is applied to the emitter thereof
through the line 48 and the line 62, the transistor 50 will
conduct.
Conduction of transistor 50 will complete a circuit between the
emitter and collector thereof to apply a potential through a line
70 to the lead 68. The lead 68 is connected to the contact 14 and
thus a potential will be applied to the contact 14 which will
enable the contact 14 to convey a 1 bit to the contact 14a of the
key receiving means. The contact 16 will convey a 0 bit of
information to the contact 16a of the key receiving means. It
should be appreciated that while a small potential might be applied
to the contacts 16 and 16a due to grounding of the base of
transistor 50, the potential will not be great enough to effect the
conveyance of a 1 bit of information to the key receiving
means.
Conduction of the transistor 50 will also enable a positive
potential to be applied along the line 70 which is connected to the
collector of transistor 52. Since at this time a potential is
applied to the base of the transistor 52 through the resistor 58
from the line 48, the transistor 52 will conduct and complete a
circuit through the collector emitter thereof to line 72. The line
72 is connected to a lead 74 which is connected to the contact 20
and the potential on line 72 will then be applied through lead 74
to the contact 20. The potential applied to the contact 20 will
enable the contact 20 to apply a 1 bit of information to the
contact 20a of the key receiving means.
The application of power to the line 48 effects the biasing of the
base of transistor 54 through the resistor 60. HOwever, since no
potential is applied to the collector of the transistor the
transistor 54 will remain in an off condition and the leads 76 and
78 which are connected to the collector and emitter thereof
respectively will not have a potential applied there along. The
leads 76 and 78 are respectively connected to the contacts 26 and
24 of the key 10 and thus a 0 bit of information will be conveyed
by the contacts 24 and 36.
The purpose of transistor 54 will be better understood if at this
point a different condition is assumed. Thus, assume that, by some
means such as a testing instrument, a potential is applied directly
to the contact 26 of the key 10. The application of a potential to
the contact 26 would effect a potential along the line 76 to the
collector of transistor 54. If at this time the base of the
transistor 54 is biased by potential on line 48, the potential
which is applied to the collector would turn transistor 54 on and
power would flow through the collector emitter circuit thereof to
the line 78 to apply a potential to the contact 24. In the assumed
condition, where a potential is applied directly to the contact 26a
the contact 24 will indicate a 1 bit of information. That naturally
departs from the predetermined code of the key and therefore
indicates indicates false code.
It should be appreciated that when a potential is applied to key
contact 26, as when the key is in position engaging the key
receiving means, the transistor 54 will conduct and the key 10 will
convey a binary coded permutation which has a 1 bit of information
at the contact 24. If however, a zero potential is applied to the
contact 26 the transistor 54 will not conduct when the key engages
the key receiving means and accordingly a 0 bit of information will
be conveyed by the contact 24. Thus, it should be apparent that the
binary coded permutation that will be conveyed by the key will
depend upon the potential applied or not applied to the contact 26.
This enables the key to convey a plurality of binary coded
permutations. Since the key will convey its proper binary coded
permutation only when a potential is applied to a certain key
contact or contacts, in this example including the contact 26, the
proper permutation will be disguised when the key is removed from
the key receiving means.
At this point, attention may be called to the fact that the key can
be utilized to offer a second code permutation that may be desired.
Thus, in the circuitry described, the contact 24 can offer either a
1 or a 0 bit of information. Therefore, depending upon the
predetermined binary coded permutation needed to actuate the
security system, a potential may or may not be applied to the
contact 26 and the transistor 54 may or may not be utilized to
direct a 1 bit of information to the contact 24.
When the key 10 is engaged with the key receiving means the binary
coded permutation is applied to the key receiving means via the
contacts 14-30 of the key 10. The binary coded information, which
consists of the 1 bits of information applied by the contacts 14,
18, 20, 22, and 28 and the 0 bits of information which are applied
by the contacts 16, 24, 26, and 30, is controlled by the presence
or absence of conductive portions between the bus bar 40 and the
contacts 14 to 30, the operation of the control means 38, and the
electrical condition of the key receiving means contacts 14a to
32a. It should be apparent from all of the foregoing that the
control means has a first condition when the key 10 is engaged with
the key receiving means and the contacts 14 to 32 engage the
contacts 14a to 32a and a second condition when the key is not
engaged with the key receiving means. The second condition of the
control means is such as to effectively prevent deciphering of the
code stored on the key 10 when the key is not engaged with the key
receiving means. Moreover, the body 12 of the key is preferably
made of a material which prevents X-ray of the key, and which also
renders the circuitry destroyed if the key is taken apart. Thus, if
the key 10 falls into the hands of an unauthorized person, he
cannot duplicate the code stored on the key without destroying the
key.
There are three general types of testing that might be attempted to
determine the binary coded permutation of the key. Perhaps the most
obvious test would be to use a battery and a light to test the
conductivity of the different terminals by engaging the contacts of
the battery and light with different contacts of the key. A test
such as this applied to the key would show that the terminals 18,
22, 28 and 32 are closed circuits. A person using this test would
have no way of knowing that the contacts 14, 20 are also closed
circuits. Thus, deciphering of the code by this method would not be
productive.
A more sophisticated test would be to use an ohmmeter and measure
the resistance of all the terminals. In this type of test it should
be appreciated that the resistances of the terminals 14, 16, 20,
24, 26 and 32 would all be about the same due to their connection
with the control means 38. Therefore, the distinction between these
terminals could not be found by using an ohmmeter. In a further
attempt to decipher the key, power might be applied to one of the
terminals and the output of the different terminals measured.
However, it should be apparent that if power were applied to the
terminal 32 it would be necessary to ground terminal 16 in order
for the code to be deciphered thereon since transistor 50 will not
conduct unless there is a certain potential through terminal 16.
Thus, unless it is known specifically what terminals to ground and
what terminals to apply power to, it will be exceedingly difficult
or impossible to decipher the key. Moreover, since it is also
possible to apply power to more than one of the leads, i.e., such
as the lead 26 to bias transistor 54 into condition to thereby
obtain from the key a different code in which the contact 24 would
convey a 1 bit of information, it would be impossible for an
unauthorized person to known exactly which of the codes he might
find would be the correct code.
It should be appreciated that while only 10 terminals have been
shown in conjunction with the key, more or less terminals could be
utilized depending upon the degree of security and the number of
possible combinations desired to be utilized with the key. For
example, a plurality of contacts such as the contacts 14-32
naturally may be disposed on the opposite side of the key in a
parallel relation to the contacts 14 to 32 shown in FIG. 1. This of
course would substantially increase the number of code changes
which could be stored on a key thereby adding to the complexity of
deciphering of the key. Moreover, the complexity of the control
means can be varied to connect more or less contacts to it as the
security is desired to be increased or decreased respectively. It
should be realized that the control means illustrated is for a
particular key and, using that key as an example, persons who are
skilled in the art will be able to vary the control means to enable
different codes to be stored on the key 10.
From the foregoing it should be apparent that a new and improved
key for actuating a security system has been provided. The key
includes a plurality of contacts receiving power from the security
system and in return conveying information to the security system.
Interconnecting at least a portion of the plurality of contacts is
a control means which is operable, when the contacts of the key
engage contacts of a key receiving means of a security system to
effect the application of a predetermined code from the key to the
key receiving means of the security system. When the key is removed
from the security system the control means takes another condition
which is different from the condition of the control means when the
key engages with the key receiving means of the security system.
The second condition of the control means is such as to effectively
prevent deciphering of the predetermined code stored on the key by
an unauthorized person.
While the key of the present invention has been described in
relation to a security system that comprises a lock mechanism, it
is to be understood that the key will be of equal value where a
security system will perform other functions such as identification
of the key or the operation of different types of mechanism.
* * * * *