CA1169968A - Electronic identification system - Google Patents
Electronic identification systemInfo
- Publication number
- CA1169968A CA1169968A CA000376860A CA376860A CA1169968A CA 1169968 A CA1169968 A CA 1169968A CA 000376860 A CA000376860 A CA 000376860A CA 376860 A CA376860 A CA 376860A CA 1169968 A CA1169968 A CA 1169968A
- Authority
- CA
- Canada
- Prior art keywords
- inductor
- electromagnetic field
- identifier
- array
- identification system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/08—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
- G06K7/082—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors
- G06K7/083—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive
- G06K7/086—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive sensing passive circuit, e.g. resonant circuit transponders
Abstract
BRW:ajh ELECTRONIC IDENTIFICATION SYSTEM
ABSTRACT
An electronic identification system for reading a pre-defined identifier code. A preferred application provides a credit card sized "identifier" which includes an array of electrical inductors, some of which are elec-trically connected in a selected pattern to define the identifier code. The identifier may be positioned close-ly proximate to a substantially identical inductor array included in a "reader" so that each identifier inductor is centred over a corresponding reader inductor. An alternating current is applied to each reader inductor in turn to induce an electromagnetic field in the region surrounding the driven inductor. The electromagnetic field so pro- duced induces a voltage across the identi-fier inductor centred over the driven reader inductor.
If that identifier inductor is electrically connected to another identifier inductor(s) a current will flow in the other inductor(s) and a second electromagnetic field will be generated in the region(s) surrounding the connected inductor(s). The second electromagnetic field induces a voltage across reader inductor(s) centred under the con-nected inductor(s). Each reader inductor is separately sensed. If a current output signal is sensed at reader inductor(s) other than the driven inductor, it may be assumed that identifier inductor(s) corresponding to the driven inductor and to the reader inductor(s) at which an output signal is sensed have been electrically connected.
A master control device may thus determine the identifier code by noting those identifier inductors which are elec-trically connected.
ABSTRACT
An electronic identification system for reading a pre-defined identifier code. A preferred application provides a credit card sized "identifier" which includes an array of electrical inductors, some of which are elec-trically connected in a selected pattern to define the identifier code. The identifier may be positioned close-ly proximate to a substantially identical inductor array included in a "reader" so that each identifier inductor is centred over a corresponding reader inductor. An alternating current is applied to each reader inductor in turn to induce an electromagnetic field in the region surrounding the driven inductor. The electromagnetic field so pro- duced induces a voltage across the identi-fier inductor centred over the driven reader inductor.
If that identifier inductor is electrically connected to another identifier inductor(s) a current will flow in the other inductor(s) and a second electromagnetic field will be generated in the region(s) surrounding the connected inductor(s). The second electromagnetic field induces a voltage across reader inductor(s) centred under the con-nected inductor(s). Each reader inductor is separately sensed. If a current output signal is sensed at reader inductor(s) other than the driven inductor, it may be assumed that identifier inductor(s) corresponding to the driven inductor and to the reader inductor(s) at which an output signal is sensed have been electrically connected.
A master control device may thus determine the identifier code by noting those identifier inductors which are elec-trically connected.
Description
9 ~ ~
ELECTRONIC IDENTIFICATION SYSTEM
Field of the Invention This invention relates to electronic i.dentification systems and, in particular, electronic S identification systems which sense ("read") the electro-magnetic characteristics of an identifier which bears an identifier code.
Background of the Invention -Several types of electronic identification sys-tems are known. Optical systems typically provide elec-tronic means for optically reading features presented ina defined pattern ~typically holes in a punched card) which comprises an identifier code recognizable by the system~ Optical systems suEfer several disadvantages including the fact that they are frequently easily cir-cumvented since the optical identifier code is ofteneasily duplicated. Furthermore, optical systems may suffer a degradation in performance due to wearing of the optically-encoded identifier and due to the presence of ;20 dirt or other foreign matter on either the optical reader, the identifier, or both.
: Magnetically encoded electronic identification systems usually offer better security than optically : encoded systems since the magnetic code on an identifier 25~ ~ ~ lS~ invisible (typically, the identifier comprises a sub-strate having a strip of magnetic material which is mag-netlzed in a predetermined pattern which defines the : identif~ier code). However, magnetic systems suffer several d~i~sadvantages including susceptibility to wear ; 30 (for example, a magnetic oxide~trip placed upon a : ::
, ~ ~ 69~6f~
card-type identifier substrate may eventually wear off);
the magnetic code on the identifier may be accidentally altered or erased; and, dirt or other foreign matter on the magnetic reader, the identifier, or both/ may degrade system performance by introducing errors when the system attempts to read the code on the identifier.
Surnmary of the Invention The invention is directed to an electronic identification system, comprising drive means for produc-ing a first electromagnetic field at a first location, detector means for producing an output signal upon detec-tion of a second electromagnetic field ak a second loca-tion where the first electromagnetic field has a neglig-ible effect upon the detector means, and identifier means Eor sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the first electromagnetic field; the identi-fier means being physically separable from the drive means and from the detector means.
The drive means may include a first electrical inductor about which the first electromagnetic field is induced in response to an applied current. The detector means may include a second electrical inductor in which the output signal is induced when the second electro-magnetic field surrounds the second inductor. The ident-;~ ifier means may comprise a third elec~rical inductor and a fourth electrical inductor connected in series with the third electrical inductor.
In one embodiment, the invention provides an electronic identification system, comprising a plurality 1 ~ 699~3 of drive means, each separately responsive to an applied current to produce a first electromagnetic field, a plurality of detector means, each separately responsive to an applied second electromagnetic field -to produce an output signal and identifier means for detecting the Eirst electromagnetic field and producing the second electromagnetic field in response thereto~
Advantageously, means are provided for select-ively applying a current to one of the drive means, thereby producing the first electromagnetic field. Means may also be provided for scanning each of the detector means to detect the second electromagnetic field.
Preferably, the identifier means is physically separable from the drive means and from the detector means.
The identifier means includes means for sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the irst electromagnetic fleId.
~; 20 Preferably, each drive means includes an elec-trical inductor for producing the first electromagnetic fieId and each detector means includes an electrical lnductor responsive to the second electromagnetic field.
Preerably the identifier means comprises at least two ~ electrical inductors connected in series. Advantage-ously, each inductor included in one of the drive means is also included in one of the detector means. The inductors included in the drive means and in the detector means may be positioned in a first array. The identifier means may include a plurality of electrical inductors . .
9 6 ~3 positioned in a second array substantially identical to the first array.
The invention also provides an electronic identification system, comprising a first array of elec-trical inductors, means :Eor applying a current to one of the inductors to produce a first electromagnetic field, and means for scanning each inductor in the Eirst array to detect a second electromagnetic Eield at another in-ductor in the first array. Identifier means which in-cludes a second array of electrical inductors substan-tially identical to the first array are provided. Advan-tageously, the identifier is physically separable from remaining components of the electronic identification system. Two or more inductors of ~he second array are lS electrically connected whereby, when the inductors of the second array are centred over corresponding inductors of ; the first array and placed closely proximate thereto, a current applied to an inductor in ~he first array induces ~the first electromagnetic field which induces a current : 20 in an adjacent inductor of the second array which induced ;~ : current produces the second electromagnetic field in other inductors of the second array which are electrical-ly connected to the adjacent inductor.
: Brief Description of the Drawing ~25 : : Figure 1 is a simplified schematic diagram of ~:an;electronic identification system having 2 inductors in the "reader" and 2 inductors on the l'identifier";
Figure ? is an electronic schematic circuit diagram of a reader having 24 inductors;
Figure 3 is an electronic schematic circuit dia-gram o one of the drive amplifiers included in Figure 2;
_ ~ _ i$ ~
.
1 3 ~'~9~
Figure 4 is an electronic schematic circuit diagram of one of the sensors included in Figure 2;
Figure 5 is a plan view of one side of an in-ductor array which may be included in either the identi-fier or the reader of a 24 inductor electronic identific-ation system; and, Figure 6 is a graph including representative waveforms illustrative of the sequence of operations of the reader of Figure 2.
Description of a Preferred Embodiment The electronic identification system to be de-scribed includes a "reader" and a separate "identifier".
A separate identifier would be provided for each indi-vidual, piece of equipment, or the like which is to be "identified". 'me reader includes electronic circuitry for detecting a code which has been included (as herein-after described) on a given identifier.
It is to be understood that the reader is to be controlled by a master control device (such as a com-puter) capable of causing the reader to perform its vari-o~us intended functions, analyzing the results of thereader~'s performance and taking appropriate steps as desired, depending upon the particular application. The ~; description of the preferred embodiment deals with one way that the master control device might control the `
reader. However, the construction and operation of the master control device is not considered to form a part of the~invention. Accordingly, no detailed description of the master control device is included herein. similarly, the invention may be applied to a wide range of uses such :
~:
. .
, 1 ~ B996C3 as access control systems, identity monitoring systems, point of sale terminals, or the like. Depending upon the particular application, the master control device might simply record the time of day and the code of a particu-lar identifier presented to the reader. In some applica-tions, presentation of a specific identifier might cause the master control device to enable access to controlled premises or equipment. Such applications are described by way of example only and are not to be taken as limit-ing the scope of the invention defined in the appendedclaims.
E~igure 1 depicts a simplified electronic iden-tification system which illustrates the principle of operation of the present invention. The reader includes an inductor A positioned at a first location, and an inductor D positioned at second location. A drive ampli-fier is electrically connected to inductor A to form a drlve means. A sensor is electrically connected to inductor D to form a detector means.
~ rme identifier comprises a pair of inductors B
and C which are fixed on a substrate in the same relative ~; location that inductors A and D are positioned relative to one another. Thus, if the identifier is physically removed from the reader, it may later be repositioned 25 ~ w1th~respect to the reader with inductors A and B closely proximate ~ne another and centred over tor under, or be-slde~, as the case may be) one another and with inductors C and D closely proximate one another and centred with respect to one another~
~::
: :
1 169~3G~
If the drive amplifier oE Figure 1 is energized to cause an al~ernating current to flow in inductor A
(and assuming that inductors A and D on the one hand and inductors B and C on the other are positioned sufficient-ly far apart that the effects of any mutual inductancebetween inductor pairs is negligible) then a first elec-tromagnetic field will be induced in the region surround-ing inductor A. If inductor B is positioned sufficiently close to inductor A, then the electromagnetic field sur-rounding inductor A will induce a voltage across inductorB. If inductor B is connected to lnductor C, then a cur-rent will flow in inductor C, and a second electromagnet-ic field will be induced in the region surrounding in-ductor C. Inductors B and C thus serve as an identifier means for sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the first electromagnetic field. If inductor D is positioned sufficiently close to inductor C, then the second electromagnetic field will induce a current in inductor D which current may be used by the detector means to produce an output signal for detection by the master control device.
Inductors B and C each have two terminals which may be connected together in series in one of two differ-~ ent ways (i.e. corresponding terminals on each inductormay be connected together or, alternatively, the two terminals may be cross-connec~ed). The phase of the :
current signal induced to flow in inductor D will depend upon the~method selected to connect the terminals of inductors B and C togethe~.
.
~ 1 6~9G':~
The apparatus of Figure l comprises a 2 induc-tor "electronic identification system" having an identi-fier ~hich may include one of two different identifier codes corresponding to the two possible methods for con-necting inductors B and C. The master control device may control the reader by applying an alternating current signal to the drive amplifier to induce an electromagnet-ic field in the region surrounding inductor A. Concur-rently, the master control device may examine the output of the detector means to detect a current induced in in-ductor D in response to an electromagnetic field sur-rounding inductor D. If an appropriate output signal is not detected at the output of the detector means then several interpretations are possible:
(1) no identifier is positioned near the in-ductors included in the reader; or,
ELECTRONIC IDENTIFICATION SYSTEM
Field of the Invention This invention relates to electronic i.dentification systems and, in particular, electronic S identification systems which sense ("read") the electro-magnetic characteristics of an identifier which bears an identifier code.
Background of the Invention -Several types of electronic identification sys-tems are known. Optical systems typically provide elec-tronic means for optically reading features presented ina defined pattern ~typically holes in a punched card) which comprises an identifier code recognizable by the system~ Optical systems suEfer several disadvantages including the fact that they are frequently easily cir-cumvented since the optical identifier code is ofteneasily duplicated. Furthermore, optical systems may suffer a degradation in performance due to wearing of the optically-encoded identifier and due to the presence of ;20 dirt or other foreign matter on either the optical reader, the identifier, or both.
: Magnetically encoded electronic identification systems usually offer better security than optically : encoded systems since the magnetic code on an identifier 25~ ~ ~ lS~ invisible (typically, the identifier comprises a sub-strate having a strip of magnetic material which is mag-netlzed in a predetermined pattern which defines the : identif~ier code). However, magnetic systems suffer several d~i~sadvantages including susceptibility to wear ; 30 (for example, a magnetic oxide~trip placed upon a : ::
, ~ ~ 69~6f~
card-type identifier substrate may eventually wear off);
the magnetic code on the identifier may be accidentally altered or erased; and, dirt or other foreign matter on the magnetic reader, the identifier, or both/ may degrade system performance by introducing errors when the system attempts to read the code on the identifier.
Surnmary of the Invention The invention is directed to an electronic identification system, comprising drive means for produc-ing a first electromagnetic field at a first location, detector means for producing an output signal upon detec-tion of a second electromagnetic field ak a second loca-tion where the first electromagnetic field has a neglig-ible effect upon the detector means, and identifier means Eor sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the first electromagnetic field; the identi-fier means being physically separable from the drive means and from the detector means.
The drive means may include a first electrical inductor about which the first electromagnetic field is induced in response to an applied current. The detector means may include a second electrical inductor in which the output signal is induced when the second electro-magnetic field surrounds the second inductor. The ident-;~ ifier means may comprise a third elec~rical inductor and a fourth electrical inductor connected in series with the third electrical inductor.
In one embodiment, the invention provides an electronic identification system, comprising a plurality 1 ~ 699~3 of drive means, each separately responsive to an applied current to produce a first electromagnetic field, a plurality of detector means, each separately responsive to an applied second electromagnetic field -to produce an output signal and identifier means for detecting the Eirst electromagnetic field and producing the second electromagnetic field in response thereto~
Advantageously, means are provided for select-ively applying a current to one of the drive means, thereby producing the first electromagnetic field. Means may also be provided for scanning each of the detector means to detect the second electromagnetic field.
Preferably, the identifier means is physically separable from the drive means and from the detector means.
The identifier means includes means for sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the irst electromagnetic fleId.
~; 20 Preferably, each drive means includes an elec-trical inductor for producing the first electromagnetic fieId and each detector means includes an electrical lnductor responsive to the second electromagnetic field.
Preerably the identifier means comprises at least two ~ electrical inductors connected in series. Advantage-ously, each inductor included in one of the drive means is also included in one of the detector means. The inductors included in the drive means and in the detector means may be positioned in a first array. The identifier means may include a plurality of electrical inductors . .
9 6 ~3 positioned in a second array substantially identical to the first array.
The invention also provides an electronic identification system, comprising a first array of elec-trical inductors, means :Eor applying a current to one of the inductors to produce a first electromagnetic field, and means for scanning each inductor in the Eirst array to detect a second electromagnetic Eield at another in-ductor in the first array. Identifier means which in-cludes a second array of electrical inductors substan-tially identical to the first array are provided. Advan-tageously, the identifier is physically separable from remaining components of the electronic identification system. Two or more inductors of ~he second array are lS electrically connected whereby, when the inductors of the second array are centred over corresponding inductors of ; the first array and placed closely proximate thereto, a current applied to an inductor in ~he first array induces ~the first electromagnetic field which induces a current : 20 in an adjacent inductor of the second array which induced ;~ : current produces the second electromagnetic field in other inductors of the second array which are electrical-ly connected to the adjacent inductor.
: Brief Description of the Drawing ~25 : : Figure 1 is a simplified schematic diagram of ~:an;electronic identification system having 2 inductors in the "reader" and 2 inductors on the l'identifier";
Figure ? is an electronic schematic circuit diagram of a reader having 24 inductors;
Figure 3 is an electronic schematic circuit dia-gram o one of the drive amplifiers included in Figure 2;
_ ~ _ i$ ~
.
1 3 ~'~9~
Figure 4 is an electronic schematic circuit diagram of one of the sensors included in Figure 2;
Figure 5 is a plan view of one side of an in-ductor array which may be included in either the identi-fier or the reader of a 24 inductor electronic identific-ation system; and, Figure 6 is a graph including representative waveforms illustrative of the sequence of operations of the reader of Figure 2.
Description of a Preferred Embodiment The electronic identification system to be de-scribed includes a "reader" and a separate "identifier".
A separate identifier would be provided for each indi-vidual, piece of equipment, or the like which is to be "identified". 'me reader includes electronic circuitry for detecting a code which has been included (as herein-after described) on a given identifier.
It is to be understood that the reader is to be controlled by a master control device (such as a com-puter) capable of causing the reader to perform its vari-o~us intended functions, analyzing the results of thereader~'s performance and taking appropriate steps as desired, depending upon the particular application. The ~; description of the preferred embodiment deals with one way that the master control device might control the `
reader. However, the construction and operation of the master control device is not considered to form a part of the~invention. Accordingly, no detailed description of the master control device is included herein. similarly, the invention may be applied to a wide range of uses such :
~:
. .
, 1 ~ B996C3 as access control systems, identity monitoring systems, point of sale terminals, or the like. Depending upon the particular application, the master control device might simply record the time of day and the code of a particu-lar identifier presented to the reader. In some applica-tions, presentation of a specific identifier might cause the master control device to enable access to controlled premises or equipment. Such applications are described by way of example only and are not to be taken as limit-ing the scope of the invention defined in the appendedclaims.
E~igure 1 depicts a simplified electronic iden-tification system which illustrates the principle of operation of the present invention. The reader includes an inductor A positioned at a first location, and an inductor D positioned at second location. A drive ampli-fier is electrically connected to inductor A to form a drlve means. A sensor is electrically connected to inductor D to form a detector means.
~ rme identifier comprises a pair of inductors B
and C which are fixed on a substrate in the same relative ~; location that inductors A and D are positioned relative to one another. Thus, if the identifier is physically removed from the reader, it may later be repositioned 25 ~ w1th~respect to the reader with inductors A and B closely proximate ~ne another and centred over tor under, or be-slde~, as the case may be) one another and with inductors C and D closely proximate one another and centred with respect to one another~
~::
: :
1 169~3G~
If the drive amplifier oE Figure 1 is energized to cause an al~ernating current to flow in inductor A
(and assuming that inductors A and D on the one hand and inductors B and C on the other are positioned sufficient-ly far apart that the effects of any mutual inductancebetween inductor pairs is negligible) then a first elec-tromagnetic field will be induced in the region surround-ing inductor A. If inductor B is positioned sufficiently close to inductor A, then the electromagnetic field sur-rounding inductor A will induce a voltage across inductorB. If inductor B is connected to lnductor C, then a cur-rent will flow in inductor C, and a second electromagnet-ic field will be induced in the region surrounding in-ductor C. Inductors B and C thus serve as an identifier means for sensing the first electromagnetic field and for producing the second electromagnetic field in response to sensing of the first electromagnetic field. If inductor D is positioned sufficiently close to inductor C, then the second electromagnetic field will induce a current in inductor D which current may be used by the detector means to produce an output signal for detection by the master control device.
Inductors B and C each have two terminals which may be connected together in series in one of two differ-~ ent ways (i.e. corresponding terminals on each inductormay be connected together or, alternatively, the two terminals may be cross-connec~ed). The phase of the :
current signal induced to flow in inductor D will depend upon the~method selected to connect the terminals of inductors B and C togethe~.
.
~ 1 6~9G':~
The apparatus of Figure l comprises a 2 induc-tor "electronic identification system" having an identi-fier ~hich may include one of two different identifier codes corresponding to the two possible methods for con-necting inductors B and C. The master control device may control the reader by applying an alternating current signal to the drive amplifier to induce an electromagnet-ic field in the region surrounding inductor A. Concur-rently, the master control device may examine the output of the detector means to detect a current induced in in-ductor D in response to an electromagnetic field sur-rounding inductor D. If an appropriate output signal is not detected at the output of the detector means then several interpretations are possible:
(1) no identifier is positioned near the in-ductors included in the reader; or,
(2) the inductors on the identifier are not : centred over those in the reader (and thus the induced electromagnetic field(s) will not surround appropriate adjacent induc-tors on either the reader or the identi-fier); or,
(3) the inductors on the identifier are not connected together (Thus, no current flows ~ in inductor C. The second electromagnetic : field is therefore not present, and no current is induced in inductor D); orr
(4) the electrical characteristics of the inductors on the identifier are difEerent ~:: 30 than those expected, resulting in .
-:~ . , :
' i~9(~ 3 production of an output signal of unex-pected magnitude.
If an appropriate output signal is not detected, then the master control device should simply assume that an iden-tifier having a "valid" identiEier code has not been detected. If the particular application involves, for example, an access control system, then the master con-trol device would deny access to the controlled premises, equipment, etc. and possibly take other action such as sound an alarm.
Of course, the "electronic identification sys-tem" illustrated in Figure 1 may not be of great practi-cal value because the number of different possible iden-tifier codes is severely limited. Preferably, an elec-tronic identification system should provide a relatively large number of different possible identifier codes. If more inductors are provided, then the number of possible ~; ways of interconnecting the inductors to form different identifier codes is increased.
Figures 2 through 6 depict a practical elec-tronlc identification system which includes 24 induc~ors in the "reader" and 24 inductors in the "identifier". 24 inductors have been selected since these may, as discus-sed below, be interconnected in a relatively large number of ways, each of which may constitute a different identi-:
fier code. Also, 24 inductors of a size offering accept-able electrical characteristics may conveniently be placed on a credit card sized substrate which is easily ~; ~ carried on the person.
~;~ 30 ::
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~ ~9~36~
To simplify the description of the preferred embodiment, a number oE assumptions are made. First, it is assumed that inductors on the identifier are only to be interconnected in pairs, although no restriction is placed on the total number of connected inductor pairs.
That is, there may be from 1 to 12 pairs of connected inductors on the identifier. (If three or more inductors are to be interconnected, then the threshold of the out-put signal induced by the second electromagnetic field may be lowered, which may necessitate a modification to the reader so that such low level signals may be detected~. Second, although a given inductor pair may be interconnected in two different ways, the resulting dif-ferences in phase of the induced current output signal are ignored. That is, it is assumed that inductor pairs are either "connected", or "not connected" without regard to the manner of connection. Even if these simplifying assumptions are made, it can be shown that it is still ~; ~ possible to connect the 24 inductors on the identifier in over 3.78 x 1013 different ways. It is to be noted however that these simplifying assumptions are not in-:
tended~to limit the scope of the invention as defined in the appended claims.
Figure 5 is a plan view of a 24 inductor array
-:~ . , :
' i~9(~ 3 production of an output signal of unex-pected magnitude.
If an appropriate output signal is not detected, then the master control device should simply assume that an iden-tifier having a "valid" identiEier code has not been detected. If the particular application involves, for example, an access control system, then the master con-trol device would deny access to the controlled premises, equipment, etc. and possibly take other action such as sound an alarm.
Of course, the "electronic identification sys-tem" illustrated in Figure 1 may not be of great practi-cal value because the number of different possible iden-tifier codes is severely limited. Preferably, an elec-tronic identification system should provide a relatively large number of different possible identifier codes. If more inductors are provided, then the number of possible ~; ways of interconnecting the inductors to form different identifier codes is increased.
Figures 2 through 6 depict a practical elec-tronlc identification system which includes 24 induc~ors in the "reader" and 24 inductors in the "identifier". 24 inductors have been selected since these may, as discus-sed below, be interconnected in a relatively large number of ways, each of which may constitute a different identi-:
fier code. Also, 24 inductors of a size offering accept-able electrical characteristics may conveniently be placed on a credit card sized substrate which is easily ~; ~ carried on the person.
~;~ 30 ::
: - g _ ::
:;
~ ~9~36~
To simplify the description of the preferred embodiment, a number oE assumptions are made. First, it is assumed that inductors on the identifier are only to be interconnected in pairs, although no restriction is placed on the total number of connected inductor pairs.
That is, there may be from 1 to 12 pairs of connected inductors on the identifier. (If three or more inductors are to be interconnected, then the threshold of the out-put signal induced by the second electromagnetic field may be lowered, which may necessitate a modification to the reader so that such low level signals may be detected~. Second, although a given inductor pair may be interconnected in two different ways, the resulting dif-ferences in phase of the induced current output signal are ignored. That is, it is assumed that inductor pairs are either "connected", or "not connected" without regard to the manner of connection. Even if these simplifying assumptions are made, it can be shown that it is still ~; ~ possible to connect the 24 inductors on the identifier in over 3.78 x 1013 different ways. It is to be noted however that these simplifying assumptions are not in-:
tended~to limit the scope of the invention as defined in the appended claims.
Figure 5 is a plan view of a 24 inductor array
5~ ~which may be included in either the reader or the identi-fier.~ The inductor array for e1ther the identifier or - -the reader may be formed on one side of a credit card-sized piece of conventional printed circuit board sub-strate. Conventional printed circuit techniques may be :
;~ 30 used~to etch 24 helical coils on the substrate, each coil ;~ :::
.,, -` ~ ~ 699~, comprising an electrical inductor. This technique is desirable because the resul~ing array may be made rela-tively flat and the identifier can thus be small and easily carried on the person. The other side of the sub-strate (not shown) provides connection terminals for eachinductor. It has been found that a pattern of 24 helical coils, each having an overall diameter of about .5 inch, and each comprising 8 turns of .015 inch wide x .001 inch thick copper conductor may conveniently be etched on a credit card-sized substrate.
Preferably, the inductor arrays for both the reader and the identifier are fabricated from the same printed circuit artwork to ensure that inductors included in the reader array will have the same relative spacings as corresponding inductors included in the identifier array. Thus, the inductor array on the identifier may be positioned with each identifier inductor centred over (or under, or beside, as the case may be) a corresponding in-ductor of the reader array. This is important to ensure that an electromagnetic field induced about an inductor in one array will surround a corresponding inductor in the other array. Usage of the same printed circuit art-work to fabricate both the identifier and reader inductor arrays also ensures that the electrical characteristics o individual inductors will be more or less uniform so that the reader need not compensate for fluctuations in the output signal caused by the presence of inductors of differing electrical characteristics. (~owever, some tolerance is acceptable since it is only necessary to determine whether or not a given inductor pair on the .. . .
'3 ~ ~
iden-tifier has been connected - theoretically, any current induced to flow by the second electromagnetic field should indicate the presence of a connected induc-tor pair on the identifier). Although a satisfactory inductor array might be constructed by mounting indivi-dual inductor circuit components on a substrate, it is believed that this would lead to problems in positioning of the inductors with respect of one another, would result in a relatively bulky identifier, and would also likely be a labour-lntensive procedure and therefore relatively costly~
An identifier ha~ing a given code may be con-structed by connecting one or more selected pairs of inductors in a given pattern. (In this manner a plural-ity of distinct identifier codes may be provided. Themaster control device may be programmed to recognize each such code and, depending upon the particular application, to take appropriate action upon detection of a specified identifier code.) The identifier substrate may then be encapsulated in an opaque material such as epoxy to pre-~ent physical damage to the ind~ctor array and to prevent visual inspection of the inductor connection pattern. `!
The inductors included in the reader array are not inter-cQnnected and need only be encapsulated to protect them from physical damage.
Figure 2 is an electronic schematic circuit dlagram o~ a reader for a 24 inductor electronic identi-fication system. For ease of illustration, the 24 induc-tors included in the reader array are shown side-by-side as Ll through L24 respectively. In practice, these would : :
3 9 ~ s:3 appear in an array substantially identical to the induc-tor array on the identiEier.
The reader also includes drive amplifiers and sensors which serve analogous functions to those discus-sed with reference to Figure 1. 24 separate driveamplifiers Dl through D24 are provided - one for each of inductors Ll through L24. To simplify the reader control procedures, the 24 drive amplifiers are arranged in three groups of 8 drive amplifiers each (the groups are, res-pectively, drive amplifiers Dl through D8, D9 throughD16, and D17 through D24). Three multiplexers, MUXl, MUX2, and MUX3 are provided to sequentially activate the drive amplifiers as hereinafter described~ As shown in Figure 2, the output of drive amplifier Dl is electrical-ly connected to one terminal of inductor Ll to form afirst drive means, the output of drive amplifier D2 is electrically connected to one terminal of inductor L2 to orm a second drive means, and so on. The second termin-als of each of inductors Ll through L24 are connected to ~ the inductor supply voltage. (The "inductor supply volt-;~ age" should be distinguished from the "reader supply voltage"~ In the preferred embodiment, the reader supply voltage is 12 volts. The oscillator voltage was selected to range between 0 and 10 volts. The inductor supply voltage is thus 5 volts - the mid-range of the oscillator voltage. It is important that the reader supply voltage exceed the oscillator voltage in order to prevent damage to the multiplexors).
Figure 3 is an electronic schematic circuit diagram representative of each of drive amplifiers Dl 3 1 6~6 ~
through D24. A drive signal (the output of the oscilla-tor discussed below) may be applied via capacitor Cl to the base of transistor Ql Resistor Rl Provides biasing for Ql Capacitor C2 "tunes" the drive amp-lifier for a given oscillator frequency and inductorgeometry to ensure optimum energy transfer. (The value of capacitor C2 may be determined experimentally. For example, in a system using helical coil inductors of about .5 inches overall diameter comprising 8 turns of .015 inch by .001 inch copper conductor fabricated on a standard epoxy glass printed circuit substrate and used in a system having an oscillator frequency of 10 ~Ihz., a value of 820 pf was found appropriate for C2.) The drive amplifier output signal appears at the collector of transistor Ql The reader also includes three sensors Sl, S2 and S3. As hereinafter described, the input terminal of sensor Sl may be selectively connected to one of induc-tors Ll through L8 to form a first detector means.
Similarly, sensor S2 may be selectively connected to one .
oE inductors L9 through L16, and sensor S3 may be select-iveIy connected to one of inductors L17 through L24.
igure 4 is an electronic schematic circuit d1agram~representative of each of sensors SL, S2 or 25~ S3. If no current has been induced to flow in the in-ductor which is connected to the input ~erminal of the :~ :
sensor, then the sensor input will be pulled to the reader supply voltage through the inductor and transistor 2 will be "off", causing the output of the Schmitt trigger (integrated circuit 74C14) to be in the logic ;
1 ~ ~;996~
"low" state and its output to be in the logic "high"
state. If a current is induced to flow in the inductor which is connected to the input terminal of the sensor, then transistor Q2 Will turn "on", pulling the input of the Schmitt trigger "high" and causing its output to be "low". The master control device may examine the output of the Schmitt trigger to determine whe~her a curren~ is flowing in the inductor connected to the sensor input terminal. If the output of the Schmitt trigger is "low", then the master control device may assume that current is flowing in the inductor connected to the sensor input terminal. If the Schmitt trigger output is "high", it may be assumed that no current is flowing in the inductor connected to the sensor.
The master control device may, as described below, drive each inductor in the reader array and then determine whether a current is induced to flow in any other inductor in the reader array. In this manner the master control device may determine which pairs of induc-;~ ~ 20 tors on the identifier are connected together and thus ;~ ~ "read" the identifier code.
Operation of the reader is described with reference to figure 6 which includes representative wave-forms. Initially,~the master control device applies an 25~ ~ ~appropriate pulse (Figure 6A) to the scan counter RESET
line, resetting the counter to zero. (The scan counter is ~a conventional binary counter and is designated in Figure 2~as integrated circuit 4040). The eight output lines 0 through O7 Of the scan counter are all in the ; loglc~"low" state at this point (Figure 6C). The master i3 6 ~
control device then applies an appropriate pulse train or clock signal (Figure 6B) to the scan counter CLOCR line.
Each pulse applied to the scan counter CLOCK line incre-ments the scan coun-ter by one. For example, the first clock pulse applied to the scan counter after the reset pulse results in a logic "high" state on scan counter output line O0 and logic "low" states on scan counter output lines l through O7 (Figure 6C). The next clock pulse results in a logic "high" state on scan counter output line l and logic "low" states on scan counter output lines o0 and 2 through O7, (Figure 6C) etc~
Scan counter output lines o~ l and 2 are connected respectively to the Aor Al and A2 "select" terminals of each of multiplexers MUX4, MUX5 and MUX6. The "enable" terminals (designated "E") of each of multiplexers MUX4, MUX5 and MUX6 are grounded. Since the input to each "enable" terminal is automatically inverted by the particular integrated circuit multiplexer used in the preferred embodiment, multiplexers MUX4, MUX5 and ; MUX6 are continuously enabled. As scan counter output lines o~ l and 2 are sequentially incremented from "0" through to "7" (i.e. the sequence of scan counter output lines o~ l and 2 all "low"
25~ through to all "hlgh") each of multiplexers MUX4, MUX5 ; and MUX6 is caused to "select'i one of its eight input lines for connection to the input of the sensor coupled to the particular multiplexer. For example, with scan counter output lines o~ l and 2 in the "low"
state, multiple~er MUX4 will "select" inductor Ll for - 16 ~
- ~ 3 ~;~39~
connection to sensor Sl. Similarly, ~UX5 "selects" in-ductor L9 for connection to sensor S2 and MUX6 "selects"
inductor Ll7 for connection to sensor S3. When the scan counter is incremented so that output line O0 is "high"
and lines l and 2 are "low", MUX4 "selects" inductor L2 for connection to sensor Sl, MUX5 "selects" inductor LlO for connection to sensor S2, etc. The scan counter, MUX4, MUX5 and MUX6 thus provide a means for scanning each of the inductorsensor detector means.
Scan counter output lines 6 and O7 are connected to the "enable" terminals of multiplexers MUXl, MUX2 and MUX3. Two logic inverters and two logic "nand"
gates are positioned be~ween scan counter output lines
;~ 30 used~to etch 24 helical coils on the substrate, each coil ;~ :::
.,, -` ~ ~ 699~, comprising an electrical inductor. This technique is desirable because the resul~ing array may be made rela-tively flat and the identifier can thus be small and easily carried on the person. The other side of the sub-strate (not shown) provides connection terminals for eachinductor. It has been found that a pattern of 24 helical coils, each having an overall diameter of about .5 inch, and each comprising 8 turns of .015 inch wide x .001 inch thick copper conductor may conveniently be etched on a credit card-sized substrate.
Preferably, the inductor arrays for both the reader and the identifier are fabricated from the same printed circuit artwork to ensure that inductors included in the reader array will have the same relative spacings as corresponding inductors included in the identifier array. Thus, the inductor array on the identifier may be positioned with each identifier inductor centred over (or under, or beside, as the case may be) a corresponding in-ductor of the reader array. This is important to ensure that an electromagnetic field induced about an inductor in one array will surround a corresponding inductor in the other array. Usage of the same printed circuit art-work to fabricate both the identifier and reader inductor arrays also ensures that the electrical characteristics o individual inductors will be more or less uniform so that the reader need not compensate for fluctuations in the output signal caused by the presence of inductors of differing electrical characteristics. (~owever, some tolerance is acceptable since it is only necessary to determine whether or not a given inductor pair on the .. . .
'3 ~ ~
iden-tifier has been connected - theoretically, any current induced to flow by the second electromagnetic field should indicate the presence of a connected induc-tor pair on the identifier). Although a satisfactory inductor array might be constructed by mounting indivi-dual inductor circuit components on a substrate, it is believed that this would lead to problems in positioning of the inductors with respect of one another, would result in a relatively bulky identifier, and would also likely be a labour-lntensive procedure and therefore relatively costly~
An identifier ha~ing a given code may be con-structed by connecting one or more selected pairs of inductors in a given pattern. (In this manner a plural-ity of distinct identifier codes may be provided. Themaster control device may be programmed to recognize each such code and, depending upon the particular application, to take appropriate action upon detection of a specified identifier code.) The identifier substrate may then be encapsulated in an opaque material such as epoxy to pre-~ent physical damage to the ind~ctor array and to prevent visual inspection of the inductor connection pattern. `!
The inductors included in the reader array are not inter-cQnnected and need only be encapsulated to protect them from physical damage.
Figure 2 is an electronic schematic circuit dlagram o~ a reader for a 24 inductor electronic identi-fication system. For ease of illustration, the 24 induc-tors included in the reader array are shown side-by-side as Ll through L24 respectively. In practice, these would : :
3 9 ~ s:3 appear in an array substantially identical to the induc-tor array on the identiEier.
The reader also includes drive amplifiers and sensors which serve analogous functions to those discus-sed with reference to Figure 1. 24 separate driveamplifiers Dl through D24 are provided - one for each of inductors Ll through L24. To simplify the reader control procedures, the 24 drive amplifiers are arranged in three groups of 8 drive amplifiers each (the groups are, res-pectively, drive amplifiers Dl through D8, D9 throughD16, and D17 through D24). Three multiplexers, MUXl, MUX2, and MUX3 are provided to sequentially activate the drive amplifiers as hereinafter described~ As shown in Figure 2, the output of drive amplifier Dl is electrical-ly connected to one terminal of inductor Ll to form afirst drive means, the output of drive amplifier D2 is electrically connected to one terminal of inductor L2 to orm a second drive means, and so on. The second termin-als of each of inductors Ll through L24 are connected to ~ the inductor supply voltage. (The "inductor supply volt-;~ age" should be distinguished from the "reader supply voltage"~ In the preferred embodiment, the reader supply voltage is 12 volts. The oscillator voltage was selected to range between 0 and 10 volts. The inductor supply voltage is thus 5 volts - the mid-range of the oscillator voltage. It is important that the reader supply voltage exceed the oscillator voltage in order to prevent damage to the multiplexors).
Figure 3 is an electronic schematic circuit diagram representative of each of drive amplifiers Dl 3 1 6~6 ~
through D24. A drive signal (the output of the oscilla-tor discussed below) may be applied via capacitor Cl to the base of transistor Ql Resistor Rl Provides biasing for Ql Capacitor C2 "tunes" the drive amp-lifier for a given oscillator frequency and inductorgeometry to ensure optimum energy transfer. (The value of capacitor C2 may be determined experimentally. For example, in a system using helical coil inductors of about .5 inches overall diameter comprising 8 turns of .015 inch by .001 inch copper conductor fabricated on a standard epoxy glass printed circuit substrate and used in a system having an oscillator frequency of 10 ~Ihz., a value of 820 pf was found appropriate for C2.) The drive amplifier output signal appears at the collector of transistor Ql The reader also includes three sensors Sl, S2 and S3. As hereinafter described, the input terminal of sensor Sl may be selectively connected to one of induc-tors Ll through L8 to form a first detector means.
Similarly, sensor S2 may be selectively connected to one .
oE inductors L9 through L16, and sensor S3 may be select-iveIy connected to one of inductors L17 through L24.
igure 4 is an electronic schematic circuit d1agram~representative of each of sensors SL, S2 or 25~ S3. If no current has been induced to flow in the in-ductor which is connected to the input ~erminal of the :~ :
sensor, then the sensor input will be pulled to the reader supply voltage through the inductor and transistor 2 will be "off", causing the output of the Schmitt trigger (integrated circuit 74C14) to be in the logic ;
1 ~ ~;996~
"low" state and its output to be in the logic "high"
state. If a current is induced to flow in the inductor which is connected to the input terminal of the sensor, then transistor Q2 Will turn "on", pulling the input of the Schmitt trigger "high" and causing its output to be "low". The master control device may examine the output of the Schmitt trigger to determine whe~her a curren~ is flowing in the inductor connected to the sensor input terminal. If the output of the Schmitt trigger is "low", then the master control device may assume that current is flowing in the inductor connected to the sensor input terminal. If the Schmitt trigger output is "high", it may be assumed that no current is flowing in the inductor connected to the sensor.
The master control device may, as described below, drive each inductor in the reader array and then determine whether a current is induced to flow in any other inductor in the reader array. In this manner the master control device may determine which pairs of induc-;~ ~ 20 tors on the identifier are connected together and thus ;~ ~ "read" the identifier code.
Operation of the reader is described with reference to figure 6 which includes representative wave-forms. Initially,~the master control device applies an 25~ ~ ~appropriate pulse (Figure 6A) to the scan counter RESET
line, resetting the counter to zero. (The scan counter is ~a conventional binary counter and is designated in Figure 2~as integrated circuit 4040). The eight output lines 0 through O7 Of the scan counter are all in the ; loglc~"low" state at this point (Figure 6C). The master i3 6 ~
control device then applies an appropriate pulse train or clock signal (Figure 6B) to the scan counter CLOCR line.
Each pulse applied to the scan counter CLOCK line incre-ments the scan coun-ter by one. For example, the first clock pulse applied to the scan counter after the reset pulse results in a logic "high" state on scan counter output line O0 and logic "low" states on scan counter output lines l through O7 (Figure 6C). The next clock pulse results in a logic "high" state on scan counter output line l and logic "low" states on scan counter output lines o0 and 2 through O7, (Figure 6C) etc~
Scan counter output lines o~ l and 2 are connected respectively to the Aor Al and A2 "select" terminals of each of multiplexers MUX4, MUX5 and MUX6. The "enable" terminals (designated "E") of each of multiplexers MUX4, MUX5 and MUX6 are grounded. Since the input to each "enable" terminal is automatically inverted by the particular integrated circuit multiplexer used in the preferred embodiment, multiplexers MUX4, MUX5 and ; MUX6 are continuously enabled. As scan counter output lines o~ l and 2 are sequentially incremented from "0" through to "7" (i.e. the sequence of scan counter output lines o~ l and 2 all "low"
25~ through to all "hlgh") each of multiplexers MUX4, MUX5 ; and MUX6 is caused to "select'i one of its eight input lines for connection to the input of the sensor coupled to the particular multiplexer. For example, with scan counter output lines o~ l and 2 in the "low"
state, multiple~er MUX4 will "select" inductor Ll for - 16 ~
- ~ 3 ~;~39~
connection to sensor Sl. Similarly, ~UX5 "selects" in-ductor L9 for connection to sensor S2 and MUX6 "selects"
inductor Ll7 for connection to sensor S3. When the scan counter is incremented so that output line O0 is "high"
and lines l and 2 are "low", MUX4 "selects" inductor L2 for connection to sensor Sl, MUX5 "selects" inductor LlO for connection to sensor S2, etc. The scan counter, MUX4, MUX5 and MUX6 thus provide a means for scanning each of the inductorsensor detector means.
Scan counter output lines 6 and O7 are connected to the "enable" terminals of multiplexers MUXl, MUX2 and MUX3. Two logic inverters and two logic "nand"
gates are positioned be~ween scan counter output lines
6 and O7 and multiplexers MUXl, ~UX2 and MUX3 such that MUXl is "enabled" when scan counter output lines 6 and o7 are "low", MUX2 is "enabled" when scan counter output line 6 is "high" and O7 is "low", and MUX3 is "enabled" when scan counter output line 6 is "low" and O7 is "high"O Scan counter output lines O3, O4 and O5 are connected to the "select" termin-als of multiplexers MUXl, MUX2 and MUX3. As the scancounter is incremented, the oscillator output signal ~Figure 6D - note that the time scale of Figure 6D has been greatly exaggerated for purposes of illustration) i5 sequeotially applied to each of the 24 inductors through its associa~ed drive amplifier. The scan counter, MUXl, MUX2, MUX3, and the logic gates thus provide a means for selectively applyiny a current to one of the inductor-drive amplifier drive means.
~ ~ ~99~
Scan counter output line oO represents the "least significant bit" (meaning that it changes state most rapidly as the scan counter is incremented). Scan counter output line O7 represents the "most signiEicant bit" (meaning that it changes state least rapidly as the scan counter is incremented). Scan counter output line o3 changes state only after scan counter output lines O' l and 2 Undergo seven changes of state.
Thus, the input connected to each sensor may be changed seven times before any one of multiplexers MUXl, MUX2 or MUX3 is activated to "select" a different drive. When one of multiplexers MUXl, MUX2, or MUX3 is activated to select the next output, output lines o~ l and 2 will again undergo seven changes of state before another drive means is selected by multiplexers MUXl, MUX2 or MUX3. This means that a single induc-tor may ~e contin-uously driven while multiplexers MUX4, MUX5 and MUX6 each selectively connect eight inductors to sensors Sl, S2 or S3. Thus all 24 inductors may be "read" by the master control device while a single inductor is driven.
With multiplexer MUXl "enabled" and scan counter output lines O3, O4 and O5 "low", MUXl "selects" drive amplifier Dl to which the oscillator ("OSC") output signal (Figure 6D) is applied. The oscil-lator output signal (a 10 Mh~. oscillator output signalhas been used) is amplified and coupled to inductor Ll, inducing an electromagnetic field in the region surround-ing Ll. While Ll is driven, inductors Ll through L8, L9 through L16, and L17 through L24 are sequentially coupled to sensors Sl, S2 and S3 respectively. Because Ll is ` ~ :7 ~i3g6s;~
driven, an output signal should be detected when it is coupled to sensor ~1 (Figure ~E)~ The master control device may use this feature to verify correct operation of the reader. If an identifier having an appropriate inductor array is positioned closely proximate the reader array so that correspondin~ inductors in each array are centred over (or under, or beside, as the case may be) one another (the chassis housing the reader could provide a guide slot within which the identifier may be inserted for accurate positioning relative to the reader inductor array) an output signal will also be detected from induc-tors of the reader array which are adjacent inductors on the identifier that are connected to the identifier inductor which is adjacent the driven inductor. The inductors are "sensed" three at a time via sensors Sl, S2 and S3. When the eight inductors associated with each sensor have each been "read", the scan counter is incremented by the master control device and the oscil-lator output signal is applied via drive amplifier D2 to inductor L2. All 24 inductors are again "read"
while L2 is driven. (The master contro~ device shouldmaintain a record of connected pairs of inductors by noting those reader inductors in which a current is induced to flow when a given reader inductor is driven).
When all reader inductors have been driven and all other .
reader inductors separately "read", the process is com-plete. The master control device may compare the con-nected inductor pairs which have been detected with a given ldentifier code (or codes) and take appropriate action depending~upon the particular application.
9 ~ ~
It should be noted that each connected inductor pair will be detected twice since both induc-tors in the pair will be separately driven and an induced current detected in the other inductor of the pair. This "double read" characteristic may be utilized as an error-monitor-ing feature by the master control device.
m e following table lists preferred values for circuit components of a reader constructed for use with a 24 inductor electronic identification system in which -the inductors were fabricated as helical coils on a standard epoxy glass substrate. Each coil was about .5 inch in diameter and comprised 8 turns of .001 inch x .015 inch copper conductor. An oscillator frequency of 10 Mhz. was used.
Cl .01 ~f Rl 470 S~
; Ql 2N4401 C2 820 pf 20~ R2 470 S~
.
R3 10K S~
:
I4 - (SC~MITT
TRIGGER) 74C14 (integrated circuit) SCAN COUNTER 4040 (integrated circuit) NAND GATES 4011 (integrated circuit) INVERTERS 4069 (integrated circuit) MUXl~MUX6 4051 (integrated circuit) :; : ::
: ~
-It has been found that a reader constructed as described above may operate successfully if the gap be~
tween the ind~lctors in the reader and the inductors in the identifier is up to about .050 inches. Furthermore, dirt or other foreign matter accumulated on either induc-tor array does not degrade system performance since the arrays are "coupled!' by means of induced electromagnetic fields which may penetrate most foreign matter that would accumulate on the reader or identiEier under ordinary field conditions. The system is thus well suited to out-door use (for example in applications which involve moni-toring or controlling access to equipment located out~
doors) where relatively substantial accumulations of foreign matter may be expected.
Those skilled in the art will readiIy appre-ciate that by programming the master control device in an appropriate manner, very sophisticated electronic identi-fication systems may be constructed. For example, the master control device may be programmed to record the code of each identifier presented to the reader, together with the time of day. A multiplicity of readers may be provided in different locations so that the master con-trol device may keep track of personnel or equipment associated with individual identifiers, In some applica-tions, readers may be included in "point of sale" termin-als. Identifiers bearing unique codes could be provided to individual consumers for presentation at a point of sale terminal as a conventional credit card. As another example, an access control system offering excellent security may be constructed by programming the master .
.~
.
`` 1 1 ~39~
control device to deEine a given identifier code as "valid" - upon detection of an identifier bearing that code the master control device may take action to permit access to controlled equipment or premises, log the time of entry, etc. In some applications, more than one iden-tifier code may be defined as 'valid" to construct a hierarchy of valid identifier codes and appropriate action may be taken by the mas~er control device upon detection of each. An identifier might also be "dis-abled" at any time simply by chanying the program for the master control device - if desired, one or more new "valid" identifier codes could then be included in the program for the master control device. It is to be noted however that these "features" are all functions (primar-ily governed by computer programming) of the particular master control device selected, all of which may be accomodated with the preferred embodiment described.
;
~:`
:
~ ~ ~99~
Scan counter output line oO represents the "least significant bit" (meaning that it changes state most rapidly as the scan counter is incremented). Scan counter output line O7 represents the "most signiEicant bit" (meaning that it changes state least rapidly as the scan counter is incremented). Scan counter output line o3 changes state only after scan counter output lines O' l and 2 Undergo seven changes of state.
Thus, the input connected to each sensor may be changed seven times before any one of multiplexers MUXl, MUX2 or MUX3 is activated to "select" a different drive. When one of multiplexers MUXl, MUX2, or MUX3 is activated to select the next output, output lines o~ l and 2 will again undergo seven changes of state before another drive means is selected by multiplexers MUXl, MUX2 or MUX3. This means that a single induc-tor may ~e contin-uously driven while multiplexers MUX4, MUX5 and MUX6 each selectively connect eight inductors to sensors Sl, S2 or S3. Thus all 24 inductors may be "read" by the master control device while a single inductor is driven.
With multiplexer MUXl "enabled" and scan counter output lines O3, O4 and O5 "low", MUXl "selects" drive amplifier Dl to which the oscillator ("OSC") output signal (Figure 6D) is applied. The oscil-lator output signal (a 10 Mh~. oscillator output signalhas been used) is amplified and coupled to inductor Ll, inducing an electromagnetic field in the region surround-ing Ll. While Ll is driven, inductors Ll through L8, L9 through L16, and L17 through L24 are sequentially coupled to sensors Sl, S2 and S3 respectively. Because Ll is ` ~ :7 ~i3g6s;~
driven, an output signal should be detected when it is coupled to sensor ~1 (Figure ~E)~ The master control device may use this feature to verify correct operation of the reader. If an identifier having an appropriate inductor array is positioned closely proximate the reader array so that correspondin~ inductors in each array are centred over (or under, or beside, as the case may be) one another (the chassis housing the reader could provide a guide slot within which the identifier may be inserted for accurate positioning relative to the reader inductor array) an output signal will also be detected from induc-tors of the reader array which are adjacent inductors on the identifier that are connected to the identifier inductor which is adjacent the driven inductor. The inductors are "sensed" three at a time via sensors Sl, S2 and S3. When the eight inductors associated with each sensor have each been "read", the scan counter is incremented by the master control device and the oscil-lator output signal is applied via drive amplifier D2 to inductor L2. All 24 inductors are again "read"
while L2 is driven. (The master contro~ device shouldmaintain a record of connected pairs of inductors by noting those reader inductors in which a current is induced to flow when a given reader inductor is driven).
When all reader inductors have been driven and all other .
reader inductors separately "read", the process is com-plete. The master control device may compare the con-nected inductor pairs which have been detected with a given ldentifier code (or codes) and take appropriate action depending~upon the particular application.
9 ~ ~
It should be noted that each connected inductor pair will be detected twice since both induc-tors in the pair will be separately driven and an induced current detected in the other inductor of the pair. This "double read" characteristic may be utilized as an error-monitor-ing feature by the master control device.
m e following table lists preferred values for circuit components of a reader constructed for use with a 24 inductor electronic identification system in which -the inductors were fabricated as helical coils on a standard epoxy glass substrate. Each coil was about .5 inch in diameter and comprised 8 turns of .001 inch x .015 inch copper conductor. An oscillator frequency of 10 Mhz. was used.
Cl .01 ~f Rl 470 S~
; Ql 2N4401 C2 820 pf 20~ R2 470 S~
.
R3 10K S~
:
I4 - (SC~MITT
TRIGGER) 74C14 (integrated circuit) SCAN COUNTER 4040 (integrated circuit) NAND GATES 4011 (integrated circuit) INVERTERS 4069 (integrated circuit) MUXl~MUX6 4051 (integrated circuit) :; : ::
: ~
-It has been found that a reader constructed as described above may operate successfully if the gap be~
tween the ind~lctors in the reader and the inductors in the identifier is up to about .050 inches. Furthermore, dirt or other foreign matter accumulated on either induc-tor array does not degrade system performance since the arrays are "coupled!' by means of induced electromagnetic fields which may penetrate most foreign matter that would accumulate on the reader or identiEier under ordinary field conditions. The system is thus well suited to out-door use (for example in applications which involve moni-toring or controlling access to equipment located out~
doors) where relatively substantial accumulations of foreign matter may be expected.
Those skilled in the art will readiIy appre-ciate that by programming the master control device in an appropriate manner, very sophisticated electronic identi-fication systems may be constructed. For example, the master control device may be programmed to record the code of each identifier presented to the reader, together with the time of day. A multiplicity of readers may be provided in different locations so that the master con-trol device may keep track of personnel or equipment associated with individual identifiers, In some applica-tions, readers may be included in "point of sale" termin-als. Identifiers bearing unique codes could be provided to individual consumers for presentation at a point of sale terminal as a conventional credit card. As another example, an access control system offering excellent security may be constructed by programming the master .
.~
.
`` 1 1 ~39~
control device to deEine a given identifier code as "valid" - upon detection of an identifier bearing that code the master control device may take action to permit access to controlled equipment or premises, log the time of entry, etc. In some applications, more than one iden-tifier code may be defined as 'valid" to construct a hierarchy of valid identifier codes and appropriate action may be taken by the mas~er control device upon detection of each. An identifier might also be "dis-abled" at any time simply by chanying the program for the master control device - if desired, one or more new "valid" identifier codes could then be included in the program for the master control device. It is to be noted however that these "features" are all functions (primar-ily governed by computer programming) of the particular master control device selected, all of which may be accomodated with the preferred embodiment described.
;
~:`
:
Claims (30)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electronic identification system, comprising:
(a) drive means for producing a first electro-magnetic field at a first location;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field; said identifier means being physically separable from said drive means and from said detector means.
(a) drive means for producing a first electro-magnetic field at a first location;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field; said identifier means being physically separable from said drive means and from said detector means.
2. An electronic identification system as defined in Claim 1, wherein said drive means includes a first electrical inductor about which said first electromagnet-ic field is induced in response to an applied current.
3. An electronic identification system as defined in Claim 2, wherein said detector means includes a second electrical inductor in which said output signal is induced when said second electromagnetic field surrounds said second inductor.
4. An electronic identification system as defined in Claim 3, wherein said identifier means comprises a third electrical inductor and a fourth electrical - Page 1 of Claims -inductor connected in series with said third electrical inductor.
5. An electronic identification system, compris-ing:
(a) a plurality of drive means, each separate-ly responsive to an applied current to produce a first electromagnetic field;
(b) a plurality of detector means, each separ-ately responsive to an applied second electromagnetic field to produce an output signal; and, (c) identifier control means for detecting said first electromagnetic field and pro-ducing said second electromagnetic field in response thereto.
(a) a plurality of drive means, each separate-ly responsive to an applied current to produce a first electromagnetic field;
(b) a plurality of detector means, each separ-ately responsive to an applied second electromagnetic field to produce an output signal; and, (c) identifier control means for detecting said first electromagnetic field and pro-ducing said second electromagnetic field in response thereto.
6. An electronic identification system as defined in Claim 5, further comprising means for selectively applying a current to one of said drive means, thereby producing said first electromagnetic field.
7. An electronic identification system as defined in Claim 6, further comprising means for scanning each of said detector means to detect said second electromagnetic field.
8. An electronic identification system as defined in Claim 5, 6 or 7 wherein said identifier means is physically separable from said drive means and from said detector means.
9. An electronic identification system as defined in Claim 5, 6 or 7, wherein said identifier means is physically separable from said drive means and from said - Page 2 of Claims -detector means and includes means for sensing said first electromagnetic field and for producing said second elec-tromagnetic field in response to sensing of said first electromagnetic field.
10. An electronic identification system as defined in Claim 5, 6 or 7, wherein:
(a) said identifier means is physically separ-able from said drive means and from said detector means and includes means for sensing said first electromagnetic field and for producing said second electromag-netic field in response to sensing of said first electromagnetic field; and, (b) each of said drive means includes an elec-trical inductor for producing said first electromagnetic field and wherein each of said detector means includes an electrical inductor responsive to said second elec-tromagnetic field.
(a) said identifier means is physically separ-able from said drive means and from said detector means and includes means for sensing said first electromagnetic field and for producing said second electromag-netic field in response to sensing of said first electromagnetic field; and, (b) each of said drive means includes an elec-trical inductor for producing said first electromagnetic field and wherein each of said detector means includes an electrical inductor responsive to said second elec-tromagnetic field.
11. An electronic identification system as defined in Claim 5, 6 or 7 wherein:
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-- Page 3 of Claims -tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field; and, (c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field.
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-- Page 3 of Claims -tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field; and, (c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field.
12. An electronic identification system as defined in Claim 5, 6 or 7 wherein:
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field;
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and, (d) each inductor included in one of said drive means is also included in one of said detector means.
- Page 4 of Claims -
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field;
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and, (d) each inductor included in one of said drive means is also included in one of said detector means.
- Page 4 of Claims -
13. An electronic identification system as defined in Claim 5, 6 or 7 wherein:
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field:
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and (d) each inductor included in one of said drive means is also included in one of said detector means and said inductors are positioned in a first array.
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field:
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and (d) each inductor included in one of said drive means is also included in one of said detector means and said inductors are positioned in a first array.
14. An electronic identification system as defined in Claim 5, 6 or 7 wherein:
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical - Page 5 of Claims -inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field;
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and, (d) each inductor included in one of said drive means is also included in one of said detector means, said inductors are positioned in a first array and said identifier means includes a plurality of electrical inductors positioned in a second array substantially identical to said first array.
(a) said identifier means:
(i) is physically separable from said drive means and from said detector means;
(ii) comprises at least two electrical - Page 5 of Claims -inductors connected in series; and, (iii) includes means for sensing said first electromagnetic field and for producing said second electromagne-tic field in response to sensing of said first electromagnetic field;
(b) each of said drive means includes an electrical inductor for producing said first electromagnetic field;
(c) each of said detector means includes an electrical inductor responsive to said second electromagnetic field; and, (d) each inductor included in one of said drive means is also included in one of said detector means, said inductors are positioned in a first array and said identifier means includes a plurality of electrical inductors positioned in a second array substantially identical to said first array.
15. An electronic identification system, comprising:
(a) a first array of electrical inductors;
(b) means for applying a current to one of said inductors to produce a first electro-magnetic field; and, (c) means for scanning each inductor in said first array to detect a second electro-magnetic field at another inductor in the first array;:
- Page 6 of Claims -said electronic identification system for use with identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electromagnetic field.
(a) a first array of electrical inductors;
(b) means for applying a current to one of said inductors to produce a first electro-magnetic field; and, (c) means for scanning each inductor in said first array to detect a second electro-magnetic field at another inductor in the first array;:
- Page 6 of Claims -said electronic identification system for use with identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electromagnetic field.
16. An electronic identification system as defined in Claim 15, further comprising identifier means which includes a second array of electrical inductors substan-tially identical to said first array.
17. An electronic identification system as defined in Claim 16, wherein said identifier means is physically separable from remaining components of the electronic security system.
18. An electronic identification system as defined in Claim 17, wherein two or more inductors of said second array are electrically connected whereby, when the induc-tors of said second array are centred over corresponding inductors of said first array and placed closely proxi-mate thereto, a current applied to an inductor in said first array induces said first electromagnetic field which induces a current in an adjacent inductor of said second array which induced current produces said second electromagnetic field in other inductors of said second array which are electrically connected to said adjacent inductor.
19. An electronic identification system, comprising:
(a) drive means for producing a first electro-magnetic field at a first location, said drive means including a first electrical - Page 7 of Claims -inductor about which said first electro-magnetic field is induced in response to an applied current;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, said detector means including a second electrical inductor in which said output signal is induced when said second electromagnetic field surrounds said second inductor; and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field, said identifier means including a third electrical inductor and a fourth electrical inductor connected in series with said third electrical induc-tor, and said identifier means being physically separable from said drive means and from said detector means.
(a) drive means for producing a first electro-magnetic field at a first location, said drive means including a first electrical - Page 7 of Claims -inductor about which said first electro-magnetic field is induced in response to an applied current;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, said detector means including a second electrical inductor in which said output signal is induced when said second electromagnetic field surrounds said second inductor; and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field, said identifier means including a third electrical inductor and a fourth electrical inductor connected in series with said third electrical induc-tor, and said identifier means being physically separable from said drive means and from said detector means.
20. An electronic identification system, com-prising:
(a) a plurality of drive means, each separ-ately responsive to an applied current to produce a first electromagnetic field, and each including at least one electrical - Page 8 of Claims -inductor for producing said first electro-magnetic field, (b) a plurality of detector means, each separ-ately responsive to an applied second electromagnetic field to produce an output signal, and each including at least one electrical inductor responsive to said second electromagnetic field; and, (c) identifier means for detecting said first electromagnetic field and for producing said second electromagnetic field in response thereto.
(a) a plurality of drive means, each separ-ately responsive to an applied current to produce a first electromagnetic field, and each including at least one electrical - Page 8 of Claims -inductor for producing said first electro-magnetic field, (b) a plurality of detector means, each separ-ately responsive to an applied second electromagnetic field to produce an output signal, and each including at least one electrical inductor responsive to said second electromagnetic field; and, (c) identifier means for detecting said first electromagnetic field and for producing said second electromagnetic field in response thereto.
21. An electronic identification system as defined in claim 20, wherein said identifier means comprises at least two electrical inductors connected in series.
22. An electronic identification system as defined in claim 21, wherein each inductor included in one of said drive means is also included in one of said detector means.
23. An electronic identification system as defined in claim 22, wherein the inductors included in said drive means and in said detector means are positioned in a first array.
24. An electronic identification system as defined in claim 23, wherein said identifier means includes a plurality of electrical inductors positioned in a second array substantially identical to said first array.
25. An electronic identification system as defined in claim 20, further comprising means for selectively applying a current to one of said drive means, thereby - Page 9 of Claims -producing said first electromagnetic field.
26. An electronic identification system as defined in claim 25, further comprising means for scanning each of said detector means to detect said second electromag-netic field.
27. An electronic identification system as defined in claim 20, 21 or 24 wherein said identifier means is physically separable from said drive means and from said detector means.
28. An electronic identification system as defined in claim 20, 21 or 24 wherein:
(a) said identifier means is physically separ-able from said drive means and from said detector means; and, (b) said identifier means includes means for sensing said first electromagnetic field and for producing said second electromag-netic field in response to sensing of said first electromagnetic field.
(a) said identifier means is physically separ-able from said drive means and from said detector means; and, (b) said identifier means includes means for sensing said first electromagnetic field and for producing said second electromag-netic field in response to sensing of said first electromagnetic field.
29. An electronic identification system, compris-ing:
(a) a first array of electrical inductors;
(b) means for applying a current to one of said inductors to produce-a first electro-magnetic field;
(c) means for scanning each inductor in said first array to detect a second electromag-netic field at another inductor in the first array; and, (d) identifier means including a second array - Page 10 of Claims -of electrical inductors substantially identical to said first array.
wherein two or more inductors of said second array are electrically connected whereby, when the inductors of said second array are centered over corresponding induc-tors of said first array and placed closely proximate thereto, a current applied to an inductor in said first array produces said first electromagnetic field, which induces a current in an adjacent inductor of said second array, which induced current produces said second elec-tromagnetic field in other inductors of said second array which are electrically connected to said adjacent induc-tor.
(a) a first array of electrical inductors;
(b) means for applying a current to one of said inductors to produce-a first electro-magnetic field;
(c) means for scanning each inductor in said first array to detect a second electromag-netic field at another inductor in the first array; and, (d) identifier means including a second array - Page 10 of Claims -of electrical inductors substantially identical to said first array.
wherein two or more inductors of said second array are electrically connected whereby, when the inductors of said second array are centered over corresponding induc-tors of said first array and placed closely proximate thereto, a current applied to an inductor in said first array produces said first electromagnetic field, which induces a current in an adjacent inductor of said second array, which induced current produces said second elec-tromagnetic field in other inductors of said second array which are electrically connected to said adjacent induc-tor.
30. An electronic identification system, com-prising:
(a) drive means for producing a first electro-magnetic field at a first location, said drive means including a first electrical inductor about which said first electro-magnetic field is induced in response to an applied current;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, said detector means including a second electrical inductor in which said output signal is induced when said second electromagnetic field surrounds said - Page 11 of Claims -second inductor; and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field, said identifier means including a third electrical inductor and a fourth electrical inductor and means interconnecting said third and fourth electrical inductors.
- Page 12 of Claims -
(a) drive means for producing a first electro-magnetic field at a first location, said drive means including a first electrical inductor about which said first electro-magnetic field is induced in response to an applied current;
(b) detector means for producing an output signal upon detection of a second electro-magnetic field at a second location where said first electromagnetic field has a negligible effect upon said detector means, said detector means including a second electrical inductor in which said output signal is induced when said second electromagnetic field surrounds said - Page 11 of Claims -second inductor; and, (c) identifier means for sensing said first electromagnetic field and for producing said second electromagnetic field in response to sensing of said first electro-magnetic field, said identifier means including a third electrical inductor and a fourth electrical inductor and means interconnecting said third and fourth electrical inductors.
- Page 12 of Claims -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/161,515 US4354099A (en) | 1980-06-20 | 1980-06-20 | Electronic identification system |
| US161,515 | 1980-06-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1169968A true CA1169968A (en) | 1984-06-26 |
Family
ID=22581484
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376860A Expired CA1169968A (en) | 1980-06-20 | 1981-05-05 | Electronic identification system |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4354099A (en) |
| JP (1) | JPS5730082A (en) |
| CA (1) | CA1169968A (en) |
| DE (1) | DE3122923A1 (en) |
| FR (1) | FR2485231B1 (en) |
| GB (1) | GB2079017B (en) |
| IT (1) | IT1137080B (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58151722A (en) * | 1982-03-05 | 1983-09-09 | Arimura Giken Kk | Data transmitter containing no carrier oscillator |
| JPS599783A (en) * | 1982-07-09 | 1984-01-19 | Hitachi Ltd | Card having built-in ic |
| JPS59212949A (en) * | 1983-05-18 | 1984-12-01 | Dainippon Printing Co Ltd | Ic card and its processing method and device |
| GB8332443D0 (en) * | 1983-12-06 | 1984-01-11 | Mars Inc | Tokens and handling devices |
| DE3427581A1 (en) * | 1984-07-26 | 1986-02-06 | Robert Bosch Gmbh, 7000 Stuttgart | DEVICE FOR TRANSMITTING BINARY DATA BETWEEN A MOBILE DATA CARRIER AND A FIXED STATION |
| JPS62186392A (en) * | 1986-02-12 | 1987-08-14 | Toko Inc | Signal detecting method for ic card |
| US4791283A (en) * | 1986-06-03 | 1988-12-13 | Intellicard International, Inc. | Transaction card magnetic stripe emulator |
| GB8618540D0 (en) * | 1986-07-30 | 1986-09-10 | Newman Tonks Security | Magnetic card reader |
| US5347263A (en) * | 1993-02-05 | 1994-09-13 | Gnuco Technology Corporation | Electronic identifier apparatus and method utilizing a single chip microcontroller and an antenna coil |
| JPH08102701A (en) * | 1994-09-30 | 1996-04-16 | Toshiba Corp | Drive system for magnetic coupling circuit |
| US5625327A (en) * | 1995-07-13 | 1997-04-29 | Gnuco Technology Corporation | Modified Colpitts oscillator for driving an antenna coil and generating a clock signal |
| US5594384A (en) * | 1995-07-13 | 1997-01-14 | Gnuco Technology Corporation | Enhanced peak detector |
| WO1997024689A1 (en) * | 1995-12-29 | 1997-07-10 | Dresser Industries, Inc. | Dispensing system and method with radio frequency customer identification |
| US6005387A (en) * | 1997-04-16 | 1999-12-21 | Mitutoyo Corporation | Reduced offset high accuracy induced current position transducer |
| US5936399A (en) * | 1997-09-16 | 1999-08-10 | Mitutoyo Corporation | Inductive position transducer having a multi-tap receiver winding |
| JP3994492B2 (en) * | 1997-11-28 | 2007-10-17 | 松下電器産業株式会社 | Card reader |
| US20040230487A1 (en) * | 2003-05-13 | 2004-11-18 | Tripp Jeffrey William | Local data access system |
| US20040230497A1 (en) * | 2003-05-13 | 2004-11-18 | Tripp Jeffrey William | Global marketing data system |
| US20050003839A1 (en) * | 2003-05-13 | 2005-01-06 | Tripp Jeffrey William | Decision influence data system |
| US20090159699A1 (en) * | 2007-12-24 | 2009-06-25 | Dynamics Inc. | Payment cards and devices operable to receive point-of-sale actions before point-of-sale and forward actions at point-of-sale |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2473664A (en) * | 1946-05-10 | 1949-06-21 | Joseph E Taylor | Electric locking device |
| US2774060A (en) * | 1953-06-15 | 1956-12-11 | Richard B Thompson | Detecting means for stolen goods |
| US3015087A (en) * | 1955-07-26 | 1961-12-26 | Security Systems Inc | Security system |
| US3470359A (en) | 1966-04-05 | 1969-09-30 | Fmc Corp | Anti-counterfeit document |
| US3530281A (en) * | 1966-09-13 | 1970-09-22 | Wilfred Smeiman | Data storage and readout devices |
| US3581017A (en) * | 1968-06-13 | 1971-05-25 | Aerojet General Co | Electronic multiplexer |
| DE1774618C3 (en) * | 1968-07-27 | 1973-12-13 | Bopp & Reuther Gmbh, 6800 Mannheim | Device for electrical scanning of information |
| GB1233260A (en) * | 1968-12-12 | 1971-05-26 | ||
| GB1249061A (en) | 1969-01-30 | 1971-10-06 | Revenue Systems Ltd | Improvements in or relating to data carrying cards and data storage systems |
| DE2016485A1 (en) * | 1970-04-07 | 1971-10-28 | Deutsche Geraetebau Gmbh | Machine-readable customer ID for data acquisition devices in vending machines |
| US3699311A (en) * | 1971-01-25 | 1972-10-17 | Remvac Systems Corp | Coded card and reader therefor |
| US3774205A (en) | 1971-08-02 | 1973-11-20 | Ncr Co | Merchandise mark sensing system |
| US3967161A (en) * | 1972-06-14 | 1976-06-29 | Lichtblau G J | A multi-frequency resonant tag circuit for use with an electronic security system having improved noise discrimination |
| GB1375087A (en) * | 1972-09-29 | 1974-11-27 | ||
| DE2252046A1 (en) * | 1972-10-24 | 1974-05-02 | Remvac Systems Corp | CARD WITH ENCRYPTED INFORMATION BITS AND ASSOCIATED READER |
| GB1459185A (en) | 1972-12-29 | 1976-12-22 | Group 4 Total Security Ltd | Token reader |
| GB2046968A (en) | 1979-04-17 | 1980-11-19 | Itt Consumer Products Uk Ltd | Card reader |
| GR74576B (en) * | 1980-06-13 | 1984-06-29 | Securitas Int Prod |
-
1980
- 1980-06-20 US US06/161,515 patent/US4354099A/en not_active Expired - Lifetime
-
1981
- 1981-04-23 GB GB8112628A patent/GB2079017B/en not_active Expired
- 1981-05-05 CA CA000376860A patent/CA1169968A/en not_active Expired
- 1981-05-29 IT IT22044/81A patent/IT1137080B/en active
- 1981-06-10 DE DE19813122923 patent/DE3122923A1/en not_active Withdrawn
- 1981-06-18 JP JP9312681A patent/JPS5730082A/en active Pending
- 1981-06-19 FR FR8112172A patent/FR2485231B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5730082A (en) | 1982-02-18 |
| FR2485231B1 (en) | 1989-01-06 |
| GB2079017B (en) | 1985-03-27 |
| FR2485231A1 (en) | 1981-12-24 |
| IT1137080B (en) | 1986-09-03 |
| IT8122044A0 (en) | 1981-05-29 |
| DE3122923A1 (en) | 1982-04-08 |
| US4354099A (en) | 1982-10-12 |
| GB2079017A (en) | 1982-01-13 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |