US3641498A

US3641498A - Keys for electronic security apparatus

Info

Publication number: US3641498A
Application number: US23272A
Authority: US
Inventors: Robert A Hedin
Original assignee: PHINIZY RB
Current assignee: PHINIZY RB; R B PHINIZY
Priority date: 1970-03-27
Filing date: 1970-03-27
Publication date: 1972-02-08
Anticipated expiration: 1989-02-08
Also published as: AU2690771A; FR2087896A5; GB1335416A; DE2114458A1

Abstract

A key is constructed with a base member of epoxy glass on which are electrically conductive contact strips offering a binary code permutation of open and closed circuit paths for controlling a security apparatus such as an electronic lock or computer. The code permutation can be established in the key by applying electric current that changes the state of the circuits on the key. For the purpose, the key circuits are equipped with fusible elements or magnetic memory elements. The memory elements may be of a type that will change the code when the key is used. The key may have a portion forming an identification card. In further forms the key will have eddy current rings that will react when applied to proper key-receiving means, and the key may comprise an optical mask containing a binary code in the form of a pattern of opaque and translucent areas.

Description

X5? 3 a t a MP8 We; I [151 3,641,498 Hedin 1 Feb. 8, 1972 [54] KEYS FOR ELECTRONIC SECURITY 3,399,473 9/1968 Jaffee ..40/2.2 APPARATUS 3,428,953 2/1969 Baxter et al... ....340/166X 3,525,083 8/1970 Slob et al.... ..340/166X [72] Inventor: Robert A. Hedin, San Pedro, Calif. newt.MV H.-.. V.VW,. A m. t V 73 Assignee: R. B. Phinizy, Anaheim, Calif. OTHER PUBLICATIONS [22] Filed: Mar-27,1970 Optical Hole Sensing Using Fiber Optics" Stahl et al 21 A LN 23 72 Applied Optics July 1966, Vol. 5, No. 7, p 1203-1206 1 pp 0 J 250-227) Related U.S.Applicafionl)ata Memory Array Demit et al IBM Technical Disclosure 1 [63] Continuation-in-part of Ser. No. 628,599, Apr. 5, ii-litinlgllLNglrJunegw-Rgjom173s?) 1967, abandoned, Continuation-impart of Ser. No. primary Examiner nonald J'Yusko 889,666, Dec. 31, 1969. Atwmey Teagm& Teddy [52] US. Cl. ..340/ 164 R, 340/ 166 R 57 ABSTRACT [51] Int. Cl. ..H04q 9/00 I 1 [58] Field of Search ..340/149, 166, 173, 164, 147; A key is constructed with a base member of epoxy glass on 235/61.11 A which are electrically conductive contact strips offering a binary code permutation of open and closed circuit paths for [55] Refe (3M controlling a security apparatus such as an electronic lock or computer. The code permutation can be established in the key UNITED STATES PATENTS by applying electric current that changes the state of the circuits on the key. For the purpose, the key circuits are 31788o3 4/1965 Schibfi et equipped with fusible elements or magnetic memory elements.

....... ..340/ I66 UX g g The memory elements may be of a type that will change the 3l9ll51 6 1965 34 166 code when the key is used. The key may haveaportion form- 0/ ing an identification card. In further forms the key will have 3245697 4/1966 "340/149 UX eddy current rings that will react when applied to proper key- 3,360,785 12/1967 lshidate.... .....340/166 X receiving means, and the key may comprise an optical mask 3,384,879 5/1968 Stahl et al. ..340/l66 X containing a binary code in the form of a pattern of opaque 3,396,379 8/ 1968 Chapman et al. .340/147 and translucent New 25 Claims, 21 Drawing figures KEYS FOR ELECTRONIC SECURITY APPARATUS This application is a continuation-in-part of the earlier U.S. Pat. applications of Hedin Ser. No. 628,599 filed Apr. 5. 1967, now U.S. Pat. No. 3,544,769 entitled Electronic Identification and Credit Card System, and of Hedin et al. Ser. No. 889,666 filed Dec. 31, 1969, entitled Key Controlled Electronic Security System.

BACKGROUND OF THE INVENTION 1. Field of the lnvention The present invention relates to keys that are utilized with electronic locks and other electronic security apparatus and more particularly to keys having a binary permutation code stored in a form which may be accessed electrically, magnetically or optically.

2. Description of the Prior Art Recent years have seen increasing acceptance of electronic systems for controlling entrances to protected areas and for identifying individuals without the requirement for a guard. Typically, a door may be provided with an electronic lock which responds to a preselected binary permutation code contained on a key. A person wishing to gain entrance through the door inserts his key in a receptacle associated with the lock, and lock circuitry determines if the key has the correct coding. If so, an actuation signal is provided to an electric door latch or strike; if the key has an improper code, there will be no actuation signal, and at the same time the system may generate an alarm signal.

Electronic locks have several significant advantages as compared with conventional lock systems. For example, a very large number of codes are available on a key of small size. The number of combinations available may be expressed as follows:

Total number of combinations =(n!/r!(n-r) where n is the number of available binary coded elements on the key, and r is the number of stored binary one hits required to energize the electronic lock. For example, for a key having 20 binary coded elements (n=20) used with an electronic lock requiring r=l stored binary one bits for energization, a total of l 0! l0! )=l 84,756 combinations are available.

- In electronic locks, very simple circuit changes permit the lock rapidly to be changed so as to be actuated by any of the potentially available key codes. The large number of key combinations, together with the ease with which alarm means may be incorporated in the lock, make electronic locks significantly harder to pick than mechanical systems. Moreover, a large number of remote electronic key identification stations can be monitored at a single central control station.

An electronic lock using a binary permutation coded key is described in U.S. Pat. No. 3,392,558 to R. A. Hedin et al. The circuitry employed will recognize a particular binary pennutation code stored on a key and will apply a signal to actuate a door latch or other utilization device. Other electronic lock circuitry and central electronic security systems incorporating such circuitry are set forth in the copending application Ser. No. 889,666, mentioned above.

The use of binary coded keys is not limited permutation of the circuits to control of with contacts protected key-receiving means for applying the code permutation to an electronic security apparatus, said electronic security apparatus being actuatable in response to a predetermined code permutation being applied thereto and being nonactuatable upon the application of a code permutation other than said predetermined code permutation thereto, a substantially flat, electrically nonconductive base member a plurality of electrically conductive strips mounted in spaced relation to one another on said base member, each of said strips extending longitudinally on a forward portion of said member and presenting a surface for engaging a contact of said key-receiving uses are described in the article by Robert A. Hedin entitled Electronic Identification of the Human Population for Controlled Access and Automatic Crediting", appearing in the periodical Industrial Security, Vol. 1 1, No. 2.

Described herein are a variety of keys for use in electronic locks, automatic crediting systems and the like. While referring merely to keys, it is to be understood that the keys may be formed with a portion that will bear information such as is needed on a credit or other identification card. The keys disclosed include both permanently coded and alterable data configurations. The latter keys are particularly well suited for application wherein data is to be periodically updated.

SUMMARY OF THE INVENTION In accordance with the present invention, there are set forth various keys for use with electronic locks that respond to a binary permutation code stored in the key. l mention locks for convenience of description, and when referring to a lock I intend to include other electronic security apparatus that will be controlled by a key. In different embodiments, the code may be entered in the key at the time of manufacture, entered subsequent to manufacture and thereafter permanently retained, or entered and/or revised at any time. Depending upon the embodiment, the codes may be sensed electrically, magnetically or optically.

In one form, the key code may comprise a permutation of open or closed AC or DC electrical paths in a circuit printed or etched on an electrically insulative substrate or base member. Keys of this type may be precoded at the time of manufacture. However, as a feature of my invention 1 may equip the keys with elements for subsequent entry of a binary code permutation.

More particularly, the keys may have memory elements for storage of the code. These memory elements may comprise singleor multiple-apertured magnetic cores or other magnetic storage elements, or may comprise a diode or transistor matrix. Certain of the magnetic memory element keys are particularly well adapted for the storage of data which is to be altered from time to time.

Another key embodiment incorporates a plurality of electrically conductive strips of ring shape located at selected positions on an electrically insulative, nonmagnetic base member substrate. The location of these eddy current rings, the presence of which may be sensed magnetically, represent the code of the key. In yet another embodiment, the-key may include an optical mask containing a pattern of transparent and opaque areas that form the coding of the key. The position of the optically coded regions may be sensed using a fiber optic bundle and an associated plurality of photodetectors.

Thus, it is an object of the present invention to provide improved keys for use with an electronic lock or other electronic device that will respond to a binary code permutation of electrical circuits.

It is another object of the present invention to provide keys for electronic locks, which keys contain binary codes which may be sensed electrically, magnetically or optically.

Another object of the present invention is to provide various embodiments of keys for electronic locks, wherein a code may be represented on a key by open or closed electrical paths in a printed circuit, by data stored in magnetic or other memory elements, by positions of active components in a diode or transistor matrix, by the location of eddy current rings on a nonmagnetic substrate, or by the juxtaposition of opaque and transparent regions in an optical mask.

Still another object of the present invention is to provide keys having planar, electrically insulative base members or substrates, a set of spaced, parallel conductive strip terminals adjacent a common edge of the substrate and means for electrically connecting or disconnecting selected terminals to a common conductor also disposed on the substrate.

It is still another object of the present invention to provide keys incorporating an electrically insulative substrate or base member having a plurality of conductive members ofl'ering contact-engaging surfaces thereon, and including memory elements associated with selected members for storing a binary permutation code.

A further object of the present invention is to provide a coded device useful as an identification or credit card for use with electronic code recognition circuitry, the device containing memory elements permitting storage of alterable coded data.

It is a further object of the present invention to provide a key wherein the coding is represented by the positions of a plurality of eddy current rings on a nonmagnetic substrate.

Yet a further object of the preset invention is to provide a key including an optical mask having juxtaposed opaque and transparent regions, the coding represented thereby being determinable by use of a fiber optic bundle in conjunction with a plurality of photodetectors.

BRIEF DESCRIPTION OF THE DRAWINGS Still other objects, features and attendant advantages of the present invention will become apparent to those skilled in the art from a description of the preferred embodiments constructed in accordance herewith, taken in conjunction with the accompanying drawings, wherein like numerals designate like parts in the several figures, and wherein:

FIG. 1 is a plan view of a printed circuit key having fusible elements for the entry of a code;

FIGS. 2a and 2b respectively show the top and bottom view of another key embodiment having a pattern of open and closed electrical paths in a printed circuit;

FIGS. 3a and 3b illustrate one manner in which a key of the type shown in FIG. 1 may be constructed to obscure the coding thereof;

FIG. 4 shows a key constructed according to the invention and including an identification or credit card portion;

FIG. 5 is a simplified perspective view of a key embodiment wherein a binary code is represented by a permutation of open or closed AC electrical paths;

FIGS. 6a and 6b respectively show perspective and crosssectional views of an encapsulated key for an electronic lock;

FIG. 7 is a perspective view of a key incorporating a plurality of memory elements which store coded data;

FIG. 8 is a simplified electrical block diagram of utilization circuitry for a key of the type shovm in FIG. 7;

FIGS. 9a and 9b show various types of magnetic core devices which may be employed as memory elements in the key of FIG. 7;

FIG. 10 is a sectional view of a thin film magnetic memory element that may be utilized in the key of FIG. 7;

FIG. 11 is a perspective view of a key employing plated wire memory elements;

FIG. 12 is a simplified, somewhat diagrammatic view of a key employing a diode matrix;

FIG. 13 is a perspective view of a key employing an integrated diode or transistor matrix and requiring an appropriate access code for interrogation of the key;

FIG. 14 is an electrical schematic diagram of a transistor matrix array that may be utilized in the key of FIG. 13;

FIG. 15 is a perspective view of a key incorporating a plurality of ring-shaped electrically conductive strips, the positions of which may be detected magnetically;

FIG. 16 is a top plan view of a key incorporating an optical mask coded with opaque and transparent regions;

FIG. 17 diagrammatically illustrates apparatus for accessing the code contained in the key of FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and particularly to FIG. 1 thereof, there is shown a first embodiment of a key having certain features like those which are set forth in the copending applications mentioned above, Ser. No. 628,599 and Ser. No. 889,666. As illustrated in FIG. 1, key 10 comprises a substantially flat and generally rectangular base member or substrate 11 of electrically insulative material such as epoxy glass. Disposed on a surface of substrate 11 is a pattern 12 of electrically conductive strips, which may be fabricated in accordance with conventional electronic printed or etched circuit techniques.

Pattern 12 (FIG. 1) includes a substantially L-shaped conductor 13, which I may call a common conductor, having a first portion 13a extending transversely on a rearward portion of substrate 11. Conductor 13 also includes a second portion 13b extending toward front edge 14 so as to form a terminal offering a surface for engaging a contact of key-receiving means. Pattern 12 also includes a plurality of spaced parallel conductive strips 15 extending longitudinally on the forward portion of substrate 11 toward edge 14. Each of conductive strips 15 is electrically connected to conductor portion via a respective fuse strip 16 formed as an integral part of pattern 12. Preferably, the width of each of fuse strips 16 is significantly less than the width of the associated conductive strip 15, the latter typically being at least five times as wide as the associated fuse strip 16.

A binary code permutation of open and closed electrical paths may be provided in pattern 12 by blowing out one or more of fuse strips 16. This may be accomplished by providing an electrical current of sufficient magnitude to destroy a fuse section 16, but not so large as to cause damage to the associated conductive strip 15. For example, fuse strip 16 may be blown by providing a current of appropriate magnitude between conductor terminal portion 13b and conductive strip 15. The resultant binary permutation code would consist of three adjacent terminals 15 which are connected to common conductor 13, and one conductive strip 15 which is electrically disconnected from common conductor 13. Thus, the key 10 comprises memory means that can be changed to a state offering a particular binary code permutation that may be detected by appropriate circuitry such as that described in the aforementioned US. Pat. No. 3,392,558 to R. A. Hedin et al.

While key 10 (FIG. 1) is illustrated as having a coded conductive pattern 12 on one side only of substrate 11, the invention is not so limited and both top and bottom faces of substrate 11 could be provided with coded conductive patterns. Such conductive patterns may include a separate common conductor on each face of the substrate, or may utilize a single conductor that extends on both faces.

A key having a conductor common to both faces is illustrated in FIGS. 2a and 2b. Referring thereto, a key 19 includes a generally planar, electrically insulative substrate 20 having a top face 21, a bottom face 22, a front edge 23 and a rear edge 24. A pattern 25 of electrically conductive strips is formed on substrate 20 by conventional electronic printed circuitry techniques. Pattern 25 includes a common conductor 26 which extends along rear edge 24 and overlaps onto both front face 21 and rear face 22. Conductor 26 includes terminal portions 26a and 26b extending on respective faces 21 and 22 to front edge 23.

Disposed on top face 21 (FIG. 2a) is a first plurality of spaced parallel conductive strips 27 and 27' each of which initially is connected to common conductor 26 via a fuse strip 28 analogous to fuse strip 16 in the key embodiment of FIG. 1. Similarly, bottom face 22 includes a plurality of

conductive strips

29 and 29, each of which initially is connected to common conductor 26 by means of a fuse strip 30.

In a manner similar to that described in conjunction with FIG. 1, selected ones of fuse strips 28 and 30 may be blown to enter in key 19 (FIGS. 2a and 2b) a particular binary permutation code. By making the associated electronic lock circuitry simultaneously responsive to the coded contacts on both the top and bottom of key 19, the number of possible combinations of key 19 is considerably greater than available on a key of the same physical size but having contacts on one side only.

Alternatively, the electronic circuitry utilized with key 19 (FIGS. 2a and 2b) may be made responsive to the code on only one side (i,e., either top or bottom) of key 19. Then, by using identical patterns on the top and bottom, key 19 would operate the electronic lock regardless of whether top face 21 or bottom face 22 were inserted in a particular direction (e.g., up or down) with respect to a key-receiving means.

Key 19 also may be employed in another mode. Specifically, different codes may be entered on the top and bottom of key 19, and appropriate circuitry provided so that if key 19 were inserted with a particular face up, the lock would operate normally. If key 19 were inserted with the same face down, the coding could be such as to operate the lock while having a further function such as actuation of an alarm. With such a system, if the key holder were being forced to enter the controlled area, he could insert the key upside down"; the door would open, but at the same time a silent alarm could be transmitted to a guard or other person.

FIGS. 30 and 3b show one manner in which I construct the key so that its coding cannot be observed. Thus, a typical key 33 comprises an enclosing member 34 which may be formed of a flexible plastic or like material. Member 34 includes a pouch portion 35 into which is inserted all of key 33 except its forward portion on which are front edge 36 and the contactengaging terminals 37. Member 34 may be held assembled by an appropriate grommet 36 extending through the substrate of key 33. Member 34 further includes a flap 38 which encloses terminals 37 when key 33 is not in use, and which folds back as shown in FIG. 3a to expose terminals 37 for insertion into key-receiving means of an electronic lock. Flap 38 may be held closed (FIG. 3b) by a snap fastener 39.

As an alternative to the enclosing technique just described, the rearward portion of a key of the type shown in FIGS. 1, 2a or 2b may be coated with an opaque plastic or like material, leaving uncoated the front portion and the contact-engaging surfaces of its key terminals. Conventional identification or credit card information then may be printed and/or imbedded in the plastic coating.

A typical example of a combined credit or identification card and key is illustrated in FIG. 4. Referring thereto, identification card key 41 includes a key of the type described herein, and including a substrate or base member 42 having a front edge 43 adjacent to which is situated a plurality of terminals 44. Card key 41 includes a coating 45 on all but the terminal area of substrate 42. Printed or imbedded in coating 41 is conventional identification card information, possibly including a picture 46 and fingerprint 47 identifying the user. Such indicia is particularly advantageous for credit card applications, wherein a merchant can compare the photograph and other identifying information on the card with the features of the person presenting the card.

Referring now to FIG. 5, there is shown an embodiment of a key 50 having features like those shown in my earlier copending application Ser. No. 889,666, including a binary code permutation of open or closed AC electrical paths. In particular, the key 50 includes a planar, electrically insulative substrate or base member 51 on the surface of which is provided what I term a common conductor strip 52. Also provided on substrate 51 are a plurality of spaced terminals 53 and 53' disposed along a front edge 54 of substrate 51.

Terminals

53 and 53 are not directly electrically connected to conductor 52. Further, key 50 is provided with a pair of

conductive strip terminals

55a and 55b extending from conductor 52 toward front edge 54.

Strip terminals

55a and 55b may be used to complete a DC current path through conductor 52 when inserted into the key-receiving means of an associated electronic lock.

Referring still to FIG. 5, one or more capacitors 56 are connected between common conductor 52 and selected ones of the terminals adjacent edge 54 of key 50. In the embodiment shown, capacitors 56 are connected between conductor 52 and terminals 53. It should be apparent that while capacitors 56 complete an AC path between conductor 52 and respective terminals 53'; neither an AC nor a DC path exists between conductor 52 and terminals 53. Thus, an AC signal applied to either of

terminals

55a or 55b will be communicated via capacitors 56 to terminals 53', but will not be communicated to terminals 53. Nevertheless appropriate electronic lock circuitry will be responsive to the communicated AC signal and will detect the permutation code .of key 50.

Note that the code of key (FIG. 5) cannot be determined by measuring DC conductivity between either of terminals a or 55b and the remainder of terminals 53 and 53' due to the fact that the capacitor will not pass the DC current. Further, to prevent determination of the code by visual inspection, key 50 can be encapsulated in plastic, epoxy or the like, to provide a key of the configuration shown generally in FIG. 6a and 6b. As evident therein, a key 50' includes encapsulation material 58 covering all of substrate 51' except for front edge 54 and the terminals (generally designated 59) adjacent thereto. As indicated in FIG. 6b, encapsulation material 58 completely encloses the capacitors 56' connecting common conductor 52' with selected ones of terminals 59.

Another embodiment of a key for electronic lock or related application is illustrated in FIG. 7. Shown therein is a key 60 having a planar, electrically insulative substrate 61 forming a base member atop which are disposed a plurality of memory elements 62. Also disposed on substrate 61 is a common conductor 63 extending in substantially spaced parallel relation with a front edge 64 of key 60. A conductive strip 63a extends between common conductor 63 and front edge 64 to form a terminal for conductor 63. Further, a plurality of spaced parallel conductive strip members 63b extend from conductor 63 to respective ones of memory elements 62. A like plurality of spaced parallel conductive terminal strips 65 extend between respective memory elements 62 and key front edge 64. Another conductive strip 66 extends across key 60, intersecting each of memory element 62. The ends of conductive strip 66 extend toward front edge 64 to form terminals 66a and 66b.

The interconnections between memory elements 62, common conductor 63, terminal strips 65 and conductive strip 66 are described hereinbelow in conjunction with the typical memory elements shown in FIGS. 90, 9b, and 10. In general, each memory element 62 may comprise a magnetic or ferroelectric storage device of either the destructive or nondestructive readout type. Typically, each memory element 62 will store one binary digit (bit) of data. The data stored in memory elements 62 may be readout by providing a read current along conductive strip 66. When such read current is provided, an output voltage will appear between common conductor terminal 63a and those ones of temrinal strips 65 associated with memory elements 62 storing binary l bits. Thus, conductive strip 66 and terminal strips 65 are analogous respectively to the word line and digit drive/sense lines of a conventional magnetic core memory.

If memory elements 62 are of the destructive type, provision normally is made in the associated electronic key or related circuitry to rewrite the stored code back into memory element 62 immediately after reading the same; if nondestructive readout devices are used for memory elements 62, such rewriting is not required. Further, means may be provided for altering data in some but not all of memory elements 62. This is particularly useful when some of memory elements 62 are used to store an identification code and the remainder to store date (e.g., funds or credit available in an account) which may be updated each time the key is used.

Referring now to FIG. 8, there is shown a simplified schematic diagram'of circuitry for utilizing the key of FIG. 7. Specifically, there is a key receptacle 70 that may be like the one shown in us. pat. No. 3,392,558, including a slot 71 into which the front portion 64 of key 60 is inserted. Within key receptacle 70 are a plurality of contacts 72 which engage and make electrical contact with terminal strips 65 of the inserted key 60.

Additional contacts

72a, 72b, and 72c respectively engage terrninal 66a, 66b and 63a of key 60. A cable 73 electrically interconnects the contacts of key receptacle 70 with conventional read/write circuitry 74. Circuitry 74 may be of the type commonly used to enter data into, or read data from magnetic core memories.

The data read by circuitry 74 from memory elements 62 is provided via aline 75 to key code recognition circuitry 76. Circuitry 76 produces an output along a line 77 whenever the IAIIVI" nun code read from a set of memory elements 62 corresponds to a code preset in code recognition circuitry 76. Thus the occurrence of a signal on line 77 indicates that the correct key has been inserted in key receptacle 70.

The signal on line 77 is provided to a utilization device 78 which, in the case of electronic lock, may comprise an electric door latch. In a credit card type application, the code contained in some but not all of memory element 62 on key 60 may represent the credit card number, and code recognition circuitry 76 may be programmed to determine if the credit card number is a valid one.

In such credit card applications, utilization device 78 may include a computer for detennining the amount of credit or funds still available to the credit card holder. Alternatively, others of memory elements 62 may store data indicating the balance of funds or credit available to the credit card holder. In this case, utilization device 78 could add or subtract the amount of the credit card transaction from the previous balance stored on the key. The new balance then may be transmitted via line 79 (FIG. 8) to read/write circuitry 74 for entry of the new credit balance into key 60.

FIG. 9a shows a first embodiment of a memory element 62, comprising a conventional annular magnetic core 81. As is well known, such a magnetic core 81 has a substantially square hysteresis loop, representing two stable magnetic states. Thus if core 81 is set to the magnetic state representing a binary l, the core will remain in this state until switched to the alternate state by subsequent application of an appropriate magnetic field.

Referring to FIG. 9a, core 81 is threaded by a first wire 82 extending between segments of conductive strip 66. A second wire 83 also is threaded through core 81, and extends between conductive strip 63b and terminal strip 65.

To enter data into a core 81 which is preset to the binary state, a write current is provided between terminal 66a and 66b (FIG. 7); this current flows through wire 82. Typically, the write current will be selected so that the resultant magnetic field about wire 82 is insufi'icient to magnetize core 81 to the binary 1 state. If it is desired to set core 81 to the binary 1 state, another current simultaneously is provided between terminal 63a and the terminal strip 65 associated with the particular core 81 to be so set. The resultant current through conductor 83, together with the write current through conductor 82, produce a net magnetic field which is sufficient to set core 81 to the one state. Alternatively, if a binary 0 is to be set, no current is provided through wire 83. Since the write current through wire 82 itself is insufficient to flip core 81 from the 0 state to the 1 state, the core remains set at binary 0.

To read data from core 81, a read current is applied between terminals 66a and 66b. This read current, which flows through wire 82, is of appropriate magnitude and direction so that the resultant. magnetic field will cause core 81 to flip into the zero state. If core 81 contains a binary 0, its magnetic state will not change when the read current is applied, and no voltage will be induced in wire 83. Alternatively, if core 81 contains a binary 1, application of the read current through wire 82 will cause core 81 to flip from the binary 1 to the binary 0 state, inducing a signal in wire 83. This induced signal will appear between terminals 63a (FIG. 7) and the terminal strip 65 associated with the particular core 81. The presence or absence of such an induced signal at each of terminals 65 of key 60 (FIG. 7) thus is indicative of the data stored in corresponding memory elements 62.

Readout of core 81 (FIG. 9a) is destructive. That is, upon readout core 81 is set to the 0 state regardless of whether a binary one or binary 0 had been stored therein. Accordingly, external circuitry is necessary to rewrite the data back into core 81 if the same data is to be maintained therein. The value of a destructive readout may be appreciated when it is understood that a key thereby may be limited to one useful operation, so that a person possessing the key may have merely a single access to the electronic apparatus. Also, the apparatus if so aligned may readily apply a different code to the key. In contradistinction, the magnetic core element illustrated in FIGS. 9b offer nondestructive readout. That is, data in the core can be sensed without disturbing or destroying data contained therein.

In FIG. 9b, a two-apertured magnetic core is employed. Threading the large and

small apertures

85a and 85b of core 85 is a sense/write wire 87. Wire 87 is connected between segments of conductive strip 63b and terminal strip 65 so that a sense/write signal provided or generated between terminal 63a and a terminal strip 65 (FIG. 7) will flow through wire 87 A read wire 86, connected between segments of conductive strip 66, threads through small aperture 85b in core 85. When a read current of appropriate magnitude is provided through wire 86, a voltage is either induced or not induced in wire 87, depending on whether core 85 is storing respectively a binary lor a binary 0. In either case, the magnetic state of core 85 is not switched by application of the read current; that is, readout is nondestructive and the data bit stored in core 85 subsequently can be reaccessed from the core.

FIG. 10 shows an exemplary thin film memory element which may be employed as a memory element 62 in the key of FIG. 7. Memory element 95 is formed on a substrate 96 which could either correspond to substrate 61 of key 60 or, alternatively, could be a separate substrate that is subsequently attached to key 60. Formed on substrate 96 is a first magnetic film 97, disposed atop which is a conductive word line 98. Magnetic film 97 is oriented so that the easy axis of magnetization is parallel to word line 98. Further, word line 98 may be connected in series with segments of conductive strip 66 on key 60 (FIG. 7).

Still referring to FIG. 10, memory element 95 includes an insulation layer 99 separating the top of word line 98 from a conductive digit sense/line 100. Digit/sense line 100 itself is perpendicular to word line 98 and may be connected electrically between a conductive strip 63b and a terminal strip 65 of key 60 (FIG. 7). Another insulation layer 101 separates conductor 100 from a second magnetic film 102. Again, the easy axis of magnetization of magnetic film 102 is oriented parallel to word line 98, and perpendicular to digit/sense line 100. Finally, a protective, electrically insulating substrate 103 is disposed atop magnetic film 102.

In planar magnetic films, such as those employed in memory element 95 (FIG. 10) the flux is rotated rather than switched,

thereby affording high speed operation. Data may be readout of memory element 95 by applying an appropriate read current along word line 98. An output signal, indicative of the data stored in memory element 95, is induced on digit/sense line 100.

Yet another embodiment of a key for an electronic lock is illustrated in FIG. 11. As seen therein, a key 105 includes a planar, electrically insulative substrate 106 having a front edge 107. Disposed atop substrate 106 is a common conductor 108 having a generally L-shaped configuration, including a terminal portion 108a extending toward edge 107. A plurality of spaced parallel terminal strips 109 are disposed atop substrate 106 adjacent front edge 107. Mounted on substrate 106 is a like plurality of plated wire magnetic memory elements 110. Each element 110 includes a central conductor wire 111 connected between conductor 108 and a respective one of terminal strips 109.

Also disposed on substrate 106 of key 105 (FIG. 11) are a pair of terminal strips 112a and 112b. Electrically connected in series between terminal strips 112a and 112b is an insulated wire 113 which functions as a word line for memory elements 110. Insulated wire 113 is woven about each of memory elements 110. When a current is applied between terminal strips 1 12a and 11212, the magnetic field induced by woven word line 113 causes output signals to be generated by those memory elements 110 which are storing binary ones. These output signals appear at the corresponding ones of terminals 109. No such outputs are produced by memory elements 110 in which binary zeros are stored. As in the other key configurations described herein, the coding of the key is represented by the permutation of binary digits stored in memory elements 110.

A further form of key for an electronic lock is shown in FIG. 12. In this embodiment, a key 115 incorporates a diode matrix which is capable of providing a particular binary permutation code output in response to application of a multibit interrogation code.

As indicated diagrammatically in FIG. 12, key 115 comprises a substantially fiat, electrically nonconductive base member or substrate 116 having a top surface 116a, a bottom surface 116k and a front edge 1 17 Disposed in spaced parallel relation on substrate top surface 116a, perpendicular to edge 117, is a first plurality of conductive strips 118, 118a, 118b which serve as column conductors for the diode matrix.

Disposed on substrate bottom surface 1 16b is a second plurality of conductive strips 119, 119a, 11% which form row conductors for the matrix. A set of diodes 120, 120a, 120b are electrically connected between selected intersections of row conductors 119 and column conductors 118. For example, diode 120a is electrically connected between column conductor 118a and row conductor 119a. Similarly, diode 12% is electrically connected between column conductor 1l8b and row conductor 1 19a.

It will be appreciated that when a voltage is applied to one of row conductors 119, a corresponding output voltage will appear only on those of column conductors 118 which are diode connected to the energized row conductor. Thus if a voltage were applied only to row conductor 119a, an output voltage will appear only on column conductors 118a and 1l8b; no output voltage will appear on the others of column lines 118. Similarly, a different binary output permutation will be produced on column lines 118 if a voltage is supplied to one of the other row conductor, 119. Thus, diode matrix key 115 could be used to store information of different significance in different matrix rows. For example, the binary permutation code associated with row 119a may represent a credit card number, while information along row 11% may represent a maximum amount of credit available.

Alternatively, note that a voltage could be applied simultaneously to several of the row conductors 119, and that the resultant binary permutation output code appearing on column conductors 118 would be a function of (a) the particular ones of row conductors 119 receiving a voltage input, and (b) the specific configuration of diodes 120 in the matrix. Thus, key 115 could be accessed with a multibit interrogation code applied to row conductors 119, and would produce a particular output code only if the diode matrix were correctly configured. With this type of operation, an extremely large number of information combinations (i.e., binarypermutation codes) would be available on key 115.

The diode matrix of FIG. 12 may be constructed by utilizing discrete diodes mounted through holes in substrate 116 at the appropriate intersections between row conductors 119 and column conductors 118. Alternatively, the diode array may be in the form of integrated circuit fabricated with diodes at each matrix intersection. To code the matrix, at intersections where no diode is desired, the prefabricated diode may be blown or otherwise open circuited by application of a sufficiently large current. Another possibility is to fabricate the array with diodes only at certain preselected matrix intersections.

FIG. 13 illustrates a key employing an integrated circuit diode or transistor matrix. As indicated therein, a key 122 includes a planar, electrically insulative substrate 123 having a front edge 124. The diode or transistor matrix array is housed in a flat-pack 125 mounted on the surface of substrate 123. Electrical connections to the row conductors of the matrix are provided by a plurality of conductive strips 126 disposed on the same surface of substrate 123 and extending to front edge 124 thereof. Similarly, electrical connections to the column conductors of the matrix are provided via a plurality of spaced parallel terminal strips 127 disposed on the same surface of substrate 123 and also extending to front edge 124 thereof. When using a transistor matrix, an additional voltage connection is made to the matrix by means of a conductive strip 128 also provided on the same surface of substrate 123.

FIG. 14 is an electrical schematic diagram of a transistor matrix which may be utilized in key 122 of FIG. 13. In particular, matrix array 130 includes a plurality of bipolar transistors 131 arranged in a matrix of rows and columns. The collectors of all transistors in the array are electrically connected to a common conductor 132 to which is supplied a voltage via conductive strip 128 of key 122 (FIG. 13).

Transistor array 130 (FIG. 14) also includes a first plurality of row conductors 133 and a second plurality of column conductors 134 which may be conducted respectively to conductive strips 126 and terminal strips 127 of key 122 (FIGv 13). The base of each transistor 131 is connected to its respective row conductor 133 by means of a resistor 135.Further, the emitters of selected ones of transistors 131 are electrically connected to the respective column lines 134 via conductive links 136. The emitters of the remainder of transistors 131 are not connected to an associated column line 134, as indicated by missing links 137. The particular selected array of links 136 and missing links 137 may be provided by appropriate masking during fabrication of transistor matrix 130.

It will readily be appreciated that when an interrogate voltage is supplied on one of row lines 133, each of transistors 131 in the corresponding interrogated row will be turned on. Accordingly, a collector voltage supplied on line 132 will appear on those of column lines 134 to which transistors 131 in the interrogated row are connected by means of links 136. No such voltage will appear on the remainder of the column lines 134.

As in the case of the diode array described hereinabove, the matrix rows may be interrogated individually or, alternatively, a multibit interrogate code may be applied simultaneously to all of row lines 133 to produce a unique code along column lines 134. Further, while FIG. 14 is shown to incorporate bipolar transistors, this is not required, and metal oxide semiconductor field effect transistors (MOS FET3s) or other transistor types could be employed. l

Another key for an electronic lock, the binary permutation code of which may be sensed magnetically, is shown in FIG. 15. Specifically, a key 140 comprises a planar, electrically insulative, nonmagnetic base member or substrate 141. Disposed at selected locations on the surface of substrate 141 are a plurality of electrically conductive circular strips or eddy current rings 142.

As is well known, when an annular wire or conductive strip is exposed to a changing magnetic field, an eddy current will be induced in the annulus. The eddy current itself will produce a counter magnetic field which tends to oppose the change in the field inducing the eddy current. Thus, the presence or absence of an eddy current ring 142 at a particular location on substrate 141 may be sensed by applying a changing magnetic field at that location, and determining whether the magnitude of the field is (a) changed, indicating the presence of an annular conductive strip 142, or (b) unchanged, indicating the absence of an eddy current ring. By simultaneously or sequentially determining the presence or absence of eddy current rings 142 at a plurality of locations on the key 140, the binary permutation code of key 140 can be sensed.

An optical key for an electronic lock is illustrated in FIG. 16. As shown therein, key 145 includes a substrate 146 having an aperture 147 therein. Disposed across aperture 147 is an optical mask 148 comprising a matrix of opaque spots 149 and transparent spots 150. The coding of key 145 is determined by the particular locations of opaque spots 149. 1

Apparatus for detecting the particular code of key 145 is illustrated in FIG. 17. As seen therein, key 145 is inserted between a light source 152 and an end 153 of a fiber optic bundle 154. At the other end 156, the various fibers of bundle 155 are fanned out and directed to individual photodetectors 157. The outputs of photodetectors 157 are connected to appropriate electronic lock circuitry 158.

In operation, the transparent spots of optical mask 148 will permit light from source 152 to enter the fibers in corresponding positions in fiber optic bundle 155. The light entering these fibers will be transmitted to bundle end 156 and impinge on the associated photodetectors 157. These photodetectors will provide an output signal to lock circuitry 158. The opaque spots 149 will prevent light from source 152 from entering others of the fibers in fiber optic bundle 155. Accordingly, those of photodetectors 157 associated with nonilluminated fibers will provide no output signals to lock circuitry 158. Thus, the permutation of signals and no signals from photodetectors 157 will be indicative of the orientation of opaque spots 149 and transparent spots 150 in optical mask 148. Lock circuitry 158 may be, prewired to be responsive only to a particular optical code included in mask 148 of key 145.

While the invention has been described with respect to the preferred physical embodiments constructed in accordance therewith, it would be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention.

I claim:

1. A key for effecting operation of an electronic security apparatus by the application of a binary coded activating signal thereto, said key being adapted to contain a binary code permutation of circuits, said key comprising a plurality of electrically conductive members for engaging contacts of a key receiving means through which the permutation code may be applied to the electronic security apparatus, electrically changeable binary state memory means connected between said conductive members so as to be efi'ective when activated to establish a binary coded permutation on the key, said memory means having first and second states for establishing said binary coded permutation of circuits, said memory means when in said first state establishing one binary coded permutation of circuits and when in said second state establishing another binary coded permutation of circuits, said memory means being changeable between said first and second states to establish the one and the other binary coded permutation of circuits, said key-receiving means being operably connected to a source of power for directing power from said contacts to at least one of said conductive members to energize said hinary coded permutation of circuits and establish said binary coded permutation of circuits which is indicative of the state of said memory means, said binary coded permutation of circuits being operable when said memory means is in a predetermined one of said states to activate the electronic security apparatus, said binary coded permutation of circuits being ineffective to activate the electronic security apparatus when the memory means is in a state other than said predetermined one of said state.

2. A key as set forth in claim 1 including circuit means associated with said memory means on the key for the application of electric signals changing the state of said memory means.

3. A key as set forth in claim 2, in which said key comprises an electrically nonconductive forward portion on which said electrically conductive members are mounted in position for engaging contacts of the key-receiving means, and a portion concealing said memory means on a rearward portion of the key.

4. A key as set forth in claim 2 in which said memory means comprise electronic components forming rows and columns of an integrated matrix, said columns of said matrix being connected to corresponding ones of said electrically conductive members, and further conductive members forming parts of said circuit means for placing each row of said matrix in circuit with a contact of the key receiving means.

5. A key as set forth in claim 2, in which there is a further electrically conductive member for engaging a contact of the key-receiving means, said further member forming a part of said circuit means for the application of signals to said memory means.

6. A key as set forth in claim 5 in which said memory means comprise a magnetic memory element.

7. A key as set forth in claim 6, in which said magnetic memory element operatively associated with said circuit means and said first-mentioned conductive members.

8. A key as set forth in claim 5 in which said memory means comprise one of said first-mentioned conductive members having a portion of relatively high-electrical resistance connected to said further conductive member whereby to be destroyed when a relatively large electric current is applied through said one conductive member and said further member.

9. A key as set forth in claim 8, in which said portion of said one conductive member is a diode.

10. A key as defined in claim 2 wherein said memory means comprises a magnetic core having two stable magnetic states and said circuit means for changing the state of said magnetic core includes means for establishing a magnetic field about said magnetic core to set said magnetic core in a desired one of said stable magnetic states and further including second circuit means for reading the state of said magnetic core including means for establishing a magnetic field which causes said magnetic core to be in a predetermined one of said states, said magnetic core remaining in said one state if said magnetic core is in said one state prior to the application of said magnetic field by said second circuit means and said magnetic core changing to said one state if said magnetic core is in the other state prior to the application of said magnetic field by said second circuit means.

11. A key as defined in claim 10 wherein the application of said magnetic field by said second circuit means effects a destructive readout of the state of said magnetic core and sets said core to said one state regardless of the state said core was previously in.

12. A key as defined in claim 11 further including means for resetting said magnetic core to the state said magnetic core was in prior to the application of said magnetic field by said second circuit means.

13. A key adapted to contain binary code permutations of circuits to be connected to contacts of key receiving means for applying a predetermined code permutation to an electronic security apparatus to effect operation thereof comprises, an electrically nonconductive base member for the key, a plurality of electrically conductive members mounted in spacedrelation to one another on said base member and having each a surface in position for engaging a contact of said key-receiving means, a plurality of electrically changeable memory elements having open circuit and closed circuit states and connected each between at least two of said electrically conductive members on the base member of the key, and circuit means associated with each memory element on the key for the application of electrical signals changing the state of that element between said open and closed circuit states so as to establish a binary code permutation of circuits on the key, said circuit means being operable to effect the establishment of said predetermined and other code pennutation on said key, said key when having said other code permutation of circuits being ineffective to actuate said electronic security apparatus, said key when having said predetermined code permutation of circuits being effective to actuate said electronic security apparatus.

14. A key as set forth in claim 13 in which said base member of the key is substantially flat, each of said electrically conductive members forming a strip extending longitudinally in position on a forward portion of the base member for engaging a contact of the key-receiving means, and a conductive strip extending transversely on a rearward portion of said base member and comprising a connection between each memory element and at least two of the longitudinal strips.

15. A key as set forth in claim 13, in which each memory element comprises a circuit connected at one end to one of said electrically conductive members and at its opposed end in common with a corresponding circuit end of each other memory element.

16. A key as set forth in claim 15, in which said electrically nonconductive base member is epoxyglass and said memory elements comprise a relatively narrow fusible portion of one of said conductive members.

17. A key as set forth in claim 15, in which the key has a further electrically conductive member for placing the commonly connected circuit ends of said memory elements in circuit with a contact of the key-receiving means.

18. A key as set forth in claim 13 in which said memory means comprise each a magnetic memory element, said memory element being operatively associated with said circuit means for changing the state of the element, and said circuit means comprising a conductor that is adapted to engage a contact of the key receiving means.

19. A key adapted to contain a binary code permutation of circuits to be connected with contacts of key-receiving means for applying the code permutation to an electronic security apparatus, said electronic security apparatus being actuatable in response to a predetermined code permutation being applied thereto and being nonactuatable upon the application of a code permutation other than said predetermined code permutation thereto, a substantially flat, electrically nonconductive base member, a plurality of electrically conductive strips mounted in spaced relation to one another on said base member, each of said strips extending longitudinally on a forward portion of said member and presenting a surface for engaging a contact of said key-receiving means, a conductive common strip extending transversely on a rearward portion of said base member, changeable means placing each longitudinally extending strip individually in closed circuit or alternately in open circuit relation to said common transverse strip, and means for changing said changeable means on said key so that the key may be selectively equipped with said predetermined binary code permutations of closed and open circuits for actuating said electronic security apparatus or with said other binary code permutations os as to pervent the actuation of said electronic security apparatus in response to engagement of said plurality of electrically conductive strips with said contacts of said key-receiving means.

20. A key as set forth in claim 19 in which there are longitudinal strips and a common transverse strip on each opposed face of the base member so that the key may offer differing code permutations when applied in inverted positions to the key-receiving means.

21. A key as set forth in claim 19 in which the key comprises a member enclosing said changeable means on said rearward portion of said base member, and said enclosing member having flap portion that is movable relatively to a position covering said electrically conductive strips on the forward portion of the base member.

22. A key as set forth in claim 19 in which said changeable means comprise a plurality of memory elements electrically changeable between open circuit and closed circuit states, said key further including a conductive segmental strip extending transversely on a rearward portion of said base member, each of said memory elements having a circuit connected between a corresponding longitudinally extending strip and said common transverse strip and further having a circuit connected between segments of said segmental strip, and strip portions for placing said common and segmental strips in circuit with contacts of the key-receiving means, enabling signals supplied through the keymeans to change the state of said memory elements whereby to establish said predetermined binary code permutation that the key can reapply to the keyreceiving means to effect actuation of said electronic security apparatus.

23. A key for conveying a predetermined code to effect operation of a controlled device, said key having a plurality of electrically conductive members for engaging respective contacts of key-receiving means for conveying said predetermined code thereto to effect operation of the controlled device, a conductor in closed circuit relation to a portion of said conductive members and in open circuit relation to a further portion of said members whereby to offer a binary code permutation of circuits to said key receiving means, and a capacitor connected between said conductor and one of said conductive members, said capacitor roviding a closed circuit path between said conductor and sat one conductive member whereby AC current is applied therebetween to effect the application of said predetermined code to said key receiving means and providing an open circuit path to offer a code indication other than said predetermined code when DC current is applied through the conductive members.

24. A key for controlling an electronic security apparatus that is responsive to a predetermined binary code permutation, said key comprising an electrically nonconductive base member, a plurality of electrically conductive elements mounted in relative positions forming a binary code pattern on said base member which is indicative of said predetermined binary code permutation for controlling the security apparatus, each of said elements being shaped to form a closed electrical circuit, permitting the binary code pattern to be detected through the use of eddy currents that may be induced in each element upon the application of a changing magnetic field to said elements, said eddy currents producing a counter magnetic field which acts to oppose the changing magnetic field applied to said elements and enables the binary code pattern to be detected by sensing the magnitude of the applied magnetic field.

25. In a key for applying a predetermined binary coded permutation of electrical signals to an electric security system to effect actuation of the system and having a plurality of contacts through which the signals are transmitted to the system, circuit means connected to certain contacts of said plurality of contacts on the key for establishing a relationship between said certain contacts that is effective to transmit the predetermined binary coded permutation of electric signals to effect actuation of the system, electrically changeable state control means forming a part of said circuit means for controlling the coded relationship established between said certain contacts by the circuit means, said control means having a first state for enabling the key to apply said predetermined binary coded permutation of electric signals to effect actuation of the elec tric security system and a second state which prevents said key from applying said predetermined binary coded permutation of electric signals, said control means when in said second state rendering said key inoperative to actuate said electric security system and circuit portions through which a potential will act when externally applied to a certain combination of said contacts to change the state of said control means to said first state to enable said plurality of contacts to apply said predetermined coded permutation of signals to said electric security system to effect actuation thereof.

Claims

1. A key for effecting operation of an electronic security apparatus by the application of a binary coded activating signal thereto, said key being adapted to contain a binary code permutation of circuits, said key comprising a plurality of electrically conductive members for engaging contacts of a key receiving means through which the permutation code may be applied to the electronic security apparatus, electrically changeable binary state memory means connected between said conductive members so as to be effective when activated to establish a binary coded permutation on the key, said memory means having first and second states for establishing said binary coded permutation of circuits, said memory means when in said first state establishing one binary coded permutation of circuits and when in said second state establishing another binary coded permutation of circuits, said memory means being changeable between said first and second states to establish the one and the other binary coded permutation of circuits, said key-receiving means being operably connected to a source of power for directing power from said contacts to at least one of said conductive members to energize said binary coded permutation of circuits and establish said binary coded permutation of circuits which is indicative of the state of said memory means, said binary coded permutation of circuits being operable when said memory means is in a predetermined one of said states to activate the electronic security apparatus, said binary coded permutation of circuits being ineffective to activate the electronic security apparatus when the memory means is in a state other than said predetermined one of said state.

13. A key adapted to contain binary code permutations of circuits to be connected to contacts of key receiving means for applying a predetermined code permutation to an electronic security apparatus to effect operation thereof comprises, an electrically nonconductive base member for the key, a plurality of electrically conductive members mounted in spaced relation to one another on said base member and having each a surface in position for engaging a contact of said key-receiving means, a plurality of electrically changeable memory elements having open circuit and closed circuit states and connected each between at least two of said electrically conductive members on the base member of the key, and circuit means associated with each memory element on the key for the application of electrical signals changing the state of that element between said open and closed circuit states so as to establish a binary code permutation of circuits on the key, said circuit means being operable to effect the establishment of said predetermined and other code permutation on said key, said key when having said other code permutation of circuits being ineffective to actuate said electronic sEcurity apparatus, said key when having said predetermined code permutation of circuits being effective to actuate said electronic security apparatus.

18. A key as set forth in claim 13 in which said memory means comprise each a magnetic memory element, said memory element being operatively associated with said circuit means for changing the state of the element, and said circuit means comprising a conductor that is adapted to engage a contact of the key-receiving means.

19. A key adapted to contain a binary code permutation of circuits to be connected with contacts of key-receiving means for applying the code permutation to an electronic security apparatus, said electronic security apparatus being actuatable in response to a predetermined code permutation being applied thereto and being nonactuatable upon the application of a code permutation other than said predetermined code permutation thereto, a substantially flat, electrically nonconductive base member, a plurality of electrically conductive strips mounted in spaced relation to one another on said base member, each of said strips extending longitudinally on a forward portion of said member and presenting a surface for engaging a contact of said key-receiving means, a conductive common strip extending transversely on a rearward portion of said base member, changeable means placing each longitudinally extending strip individually in closed circuit or alternately in open circuit relation to said common transverse strip, and means for changing said changeable means on said key so that the key may be selectively equipped with said predetermined binary code permutations of closed and open circuits for actuating said electronic security apparatus or with said other binary code permutations so as to prevent the actuation of said electronic security apparatus in response to engagement of said plurality of electrically conductive strips with said contacts of said key-receiving means.

22. A key as set forth in claim 19 in which said changeable means comprise a plurality of memory elements electrically changeable between open circuit and closed circuit states, said key further including a conductive segmental strip extending transversely on a rearward portion of said base member, each of said memory elements having a circuit connected between a corresponding longitudinally extending strip and said common transverse strip and further having a circuit connected between segments of said segmental strip, and strip portions for placing said common and segmental strips in circuit with contacts of the key-receiving means, enabling signals supplied through the key-receiving means to change the state of said memory elements whereby to establish said predetermined binary code permutation that the key can reapply to the key-receiving means to effect actuation of said electronic security apparatus.

23. A key for conveying a predetermined code to effect operation of a controlled device, said key having a plurality of electrically conductive members for engaging respective contacts of key-receiving means for conveying said predetermined code thereto to effect operation of the controlled device, a conductor in closed circuit relation to a portion of said conductive members and in open circuit relation to a further portion of said members whereby to offer a binary code permutation of circuits to said key receiving means, and a capacitor connected between said conductor and one of said conductive members, said capacitor providing a closed circuit path between said conductor and said one conductive member whereby AC current is applied therebetween to effect the application of said predetermined code to said key receiving means and providing an open circuit path to offer a code indication other than said predetermined code when DC current is applied through the conductive members.

25. In a key for applying a predetermined binary coded permutation of electrical signals to an electric security system to effect actuation of the system and having a plurality of contacts through which the signals are transmitted to the system, circuit means connected to certain contacts of said plurality of contacts on the key for establishing a relationship between said certain contacts that is effective to transmit the predetermined binary coded permutation of electric signals to effect actuation of the system, electrically changeable state control means forming a part of said circuit means for controlling the coded relationship established between said certain contacts by the circuit means, said control means having a first state for enabling the key to apply said predetermined binary coded permutation of electric signals to effect actuation of the electric security system and a second state which prevents said key from applying said predetermined binary coded permutation of electric signals, said control means when in said second state rendering said key inoperative to actuate said electric security system and circuit portions through which a potential will act when externally applied to a certain combination of said contacts to change the state of said control means to said first state to enable said plurality of contacts to apply said predetermined coded permutation of signals to said electric security system to effect actuation thereof.