DE2650959B1

DE2650959B1 - Inductive reading system for magnetic cards - has transmitter coils inducing signal in receiver coil that changes in comparison with reference

Info

Publication number: DE2650959B1
Application number: DE19762650959
Authority: DE
Inventors: Juergen Ing Machate
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-11-08
Filing date: 1976-11-08
Publication date: 1978-01-12
Also published as: DE2650959C2

Abstract

The reading of information stored in the form of small magnetic elements on a plate, is achieved using an inductive reading head. The card (3) contains a matrix of small metallic elements (15) used to store data. As the card is inserted into the reader two rows of reading coils are passed. Each reading cell consists of a transmission coil (6) supplied from an A.C. generator. A receiver coil (7) is located parallel to a reference coil (8) and with no cell present the signal outputs are identical. A bridge is used to compare the signals. The presence of a cell causes the receiver coil output to fall and the reference coil signal to increase.

Description

F i g. 3 und F i g. 4 zeigen eine derartige Leseeinheit in vergrößertem Maßstab. Dabei sind die Spulen 6, 7 und 8 räumlich so angeordnet, daß ihre Mittelachsen fluchten und die Empfangsspule 7 als auch die Referenzspule 8 um die gleiche Entfernung von der verlängerten Mittelachse der Sendespule 6 nach rechts und links versetzt sind und außerdem ihr Abstand zur Sendespule derselbe ist. Wird an die Klemmen 9 und 10 der Sendespule 6 ein Wechselspannungsgenerator 21 angeschlossen, so induziert der dadurch entstehende magnetische Wechselfluß in den Spulen 7 und 8 Wechselspannungen, die an den Klemmen 11 und 12, beziehungsweise 13 und 14 meßbar sind. Infolge der F i g. 3 and F i g. 4 show such a reading unit on an enlarged scale Scale. The coils 6, 7 and 8 are spatially arranged so that their central axes align and the receiving coil 7 and the reference coil 8 by the same distance offset from the extended central axis of the transmitter coil 6 to the right and left and their distance to the transmitter coil is the same. Is connected to terminals 9 and 10 of the transmitter coil 6, an alternating voltage generator 21 is connected, so induced the resulting alternating magnetic flux in coils 7 and 8 alternating voltages, which can be measured at terminals 11 and 12 or 13 and 14. As a result of

symmetrischen Anordnung der Spulen 7 und 8 sind die in ihnen induzierten Spannungen nahezu amplituden-und phasengleich. Wird ein metallisch-leitendes Flächenelement 15 zwischen Sendespule 6 und Empfangsspule 7 geschoben, so induziert der sie durchdringende Teil des magnetischen Wechselflusses in diesem Plättchen eine Wechselspannung, die einen Kurzschlußstrom 16 zur Folge hat. Dieser Wechselstrom 16 erzeugt einen magnetischen Sekundärfluß 17, der so gerichtet ist, daß er im Bereich der Empfangsspule 7 den Primärfluß schwächt, dagegen aber im Bereich der Referenzspule 8 den Primärfluß verstärkt. Auf diese Weise wird die induzierte Spannung in der Empfangsspule 7 entsprechend reduziert und gleichzeitig die Spannung in der Referenzspule 8 erhöht. Dieser Effekt wird in der in Fig.5 dargestellten Brückenschaltung genutzt. Mit i hilfe des Potentiometers 18 wird die Brücke bei nicht eingeschobenem Plättchen so abgeglichen, daß die an den Eingängen des Verstärkers anstehende Wechselspannung nahezu zu Null wird.symmetrical arrangement of the coils 7 and 8 are those induced in them Voltages almost identical in amplitude and phase. Becomes a metallic conductive surface element 15 pushed between the transmitter coil 6 and the receiver coil 7, so induces the penetrating coil Part of the alternating magnetic flux in this platelet produces an alternating voltage that a short circuit current 16 has the consequence. This alternating current 16 generates a magnetic one Secondary flux 17, which is directed so that it is 7 in the region of the receiving coil The primary flux weakens, but the primary flux in the area of the reference coil 8 reinforced. In this way, the induced voltage in the receiving coil 7 becomes corresponding reduced and at the same time the voltage in the reference coil 8 increased. This effect is used in the bridge circuit shown in Figure 5. With the help of the potentiometer 18, the bridge is adjusted so that the plate is not inserted so that the AC voltage present at the inputs of the amplifier becomes almost zero.

Beim Einbringen des Plättchens 15 zwischen Sendespule 6 und Empfangsspule 7 wird das elektrische Brückengleichgewicht verstimmt. Die daraus resultierende Spannung wird im Verstärker 19 verstärkt und steht an dessen Ausgangsklemme zur Bewertung zur Verfügung.When inserting the plate 15 between the transmitter coil 6 and the receiver coil 7 the electrical bridge equilibrium is detuned. The resulting Voltage is amplified in amplifier 19 and is available at its output terminal Assessment available.

Das Prinzipschaltbild der gesamten Leseeinheit ist in F i g. 6 dargestellt. Das Steuerwerk 24 schaltet zyklisch eine der Oszillatorstufen 21 ein und gleichzeitig wird die jeweils zugehörige Brückenschaltung 7, 8, 18 mit Hilfe des entsprechenden steuerbaren Analogschalters 22 zum Eingang des Verstärkers 19 durchgeschaltet. Nach Gleichrichtung 23 wird das Signal zum Dateneingang eines Speichers 25 geführt. Die Adressierung des Speichers 25 beim Einschreiben erfolgt durch das Steuerwerk 24 synchron zum Zyklus der Leseeinheiten.The basic circuit diagram of the entire reading unit is shown in FIG. 6 shown. The control unit 24 cyclically switches one of the oscillator stages 21 on and at the same time is the respective associated bridge circuit 7, 8, 18 with the help of the appropriate controllable analog switch 22 connected to the input of the amplifier 19. To In rectification 23, the signal is fed to the data input of a memory 25. the The addressing of the memory 25 during writing is carried out by the control unit 24 synchronous to the cycle of the reading units.

Einen besonders ausgestalteten Datenträger zeigt F i g. 7, bei dem die dunklen Felder aus dünnen, leitenden Metallbahnen auf einem nichtleitenden Material wie Plastik oder Papier bestehen. Symmetrisch zur Mittellinie sind zwei Steuerspuren 27 und 28 sowie zehn Informationsspuren 29-1 bis 29-10 angeordnet.A specially designed data carrier is shown in FIG. 7, where the dark fields of thin, conductive metal strips on a non-conductive material like plastic or paper. Two control tracks are symmetrical to the center line 27 and 28 as well as arranged ten information tracks 29-1 to 29-10.

Jedes Informationselement 30 besteht hier aus einem geschlossenen Ring. der den Vorteil leichter Entwertbarkeit aufweist. In gleicher Weise sind metallische Vollplättchen als Informations-Elemente geeignet, wobei einem geschlossenen Ring ein Plättchen und einem getrennten Ring ein fehlendes Plättchen entspricht. Die Karte wird im Leser so geführt, daß die Empfängerspulen 7 etwa über der Mitte der zugehörigen Spuren 29-1 bis 29-10 stehen und die Referenzspulen 8 zwischen zwei, mit einem Abstand nebeneinanderliegenden Spuren stehen. Bei jeder Änderung der Information von einer der beiden zueinander versetzten Steuerspuren 27 oder 28 erfolgt die Speicherung einer Informations-Zeile. Die Information der anderen Steuerspur ermöglicht die Erkennung der Transportrichtung und bewirkt im Steuerwerk 24 eine Erhöhung oder Erniedrigung der Zeilenadresse zum Speicher um Eins. Die normale Erkennung des gesamten Dateninhaltes erfolgt durch zeilenweise Lesung und Speicherung während des kontinuierlichen Einschiebens der Karte in den Lese Eine fehlerhafte Lesung durch wechselweises hineinschieben und teilweises Herausziehen der Karte während des Lesevorganges wird durch die oben beschriebene Transportrichtungserkennung verhindert.Each information element 30 here consists of a closed one Ring. which has the advantage of being easy to cancel. In the same way are metallic Solid platelets suitable as information elements, with a closed ring a tile and a separate ring corresponds to a missing tile. the Card is guided in the reader so that the receiver coils 7 about the middle of the associated tracks 29-1 to 29-10 and the reference coils 8 between two, with a gap between adjacent tracks. Whenever the information changes the storage takes place from one of the two mutually offset control tracks 27 or 28 an information line. The information from the other control track enables this Detection of the transport direction and causes an increase or in the control unit 24 Decrease in line address to memory by one. The normal detection of the whole The data content is carried out by reading it line by line and storing it during the continuous Inserting the card into the reader. An incorrect reading by inserting it alternately and partial extraction of the card during the reading process is indicated by the above described transport direction detection prevented.

Zwei zusätzliche, induktiv lesbare Marken 31 und 32 ermöglichen die Erkennung der Kartenlage im Leser.Two additional, inductively readable marks 31 and 32 enable Recognition of the card position in the reader.

Beim Einschieben der Karte in den Leser wird mit Hilfe einer in F i g. 1 ersichtlichen Lichtschranke 26 der Kartenanfang erkannt, wodurch das Steuerwerk die Information der Spuren 29-4; 29-5; 29-6 und 29-7 al'fragt. Die beiden Marken 31 und 32 sind auf der Karte räumlich so angeordnet, daß bei jeder der vier möglichen Kartenlagen nur eine bestimmte Spur ein Informations-Element enthält. Da der Leser grundsätzlich auch bei seitenverkehrtem Einlegen der Karte die Informationselemente richtig erkennt, ist mit Hilfe dieser Marken ein Sortieren der Daten bei allen vier Kartenlagen möglich.When the card is inserted into the reader, a message shown in F i g. 1 visible light barrier 26 recognized the beginning of the card, whereby the control unit the information of lanes 29-4; 29-5; 29-6 and 29-7 asks. The two brands 31 and 32 are spatially arranged on the map so that each of the four possible Map layers only a certain track contains an information element. As the reader basically the information elements even if the card is inserted the wrong way round recognizes correctly, a sorting of the data is with the help of these marks with all four Card positions possible.

Claims

Claims: 1. Device for inductive reading of data that by means of metallic information elements applied in a certain arrangement non-conductive, card-shaped data carriers are formed, with a reading unit has two coils electrically connected in a bridge circuit, of which a coil is magnetically influenced by the information element and an electrical one Brings about detuning of the bridge, d a d u r c h g e - indicates that a one alternating magnetic flux generating primary coil is provided and also the second arranged in the bridge circuit coil magnetically influenced by the information element is that the two secondary coils are spatially arranged to each other so that in induced voltages of the same amplitude and phase for them without any information element and that when the metallic information element (15) enters through the short-circuit current developing in this element, the alternating magnetic fluxes be influenced in such a way that the amplitudes of the alternating voltages in the change both secondary coils in opposite directions.

2. Device according to claim 1, characterized in that several these reading units are arranged spatially next to one another and at a specific time Sequence one reading unit after the other is turned on and in this way the information content of a row is scanned.

3. Device according to claim 2, characterized in that the triggering the read cycles as well as the control of the saving by two on the data carrier applied, inductively readable control tracks (27, 28) takes place and that these control tracks are designed so that the transport direction of the card can be recognized with their help will.

4. Device according to claim 2, characterized in that on the Two additional inductively readable marks (31, 30) are applied to the data carrier, which are scanned at the beginning of the reading process and their spatial arrangement allows the data carrier to determine the four possible positions of the card in the reader.

The invention relates to a device for inductive reading of Data according to the preamble of claim 1.

Card-shaped and machine-readable data carriers in which the representation the information through the presence or absence of metallic platelets is formed at predetermined locations on the data carrier, the recognition of the Information on reducing the electromagnetic coupling of coils through the interposed metallic information element is based, are increasing Dimensions used for identity cards or travel and admission tickets. You wise to others, such as B. or magnetically readable data carriers have the advantage of large Robustness on. The possibility of the information elements between two opaque, difficult to separate cover layers of the data carrier gers to arrange offers the wciteren Advantages of being unrecognizable and forgery-proof.

The known readers for recognizing such information elements consist of several reading points, each of which consists of a coil to generate a, magnetic field changing over time and an associated secondary coil exist. In the secondary coil there will be a change in size and time of the coupling primary flux induced voltage proportional to the amplitude of the Recognition of the information is evaluated. When the metal plate is inserted in between induces a lower voltage. The generation of the magnetic flux can thereby both from a generator or z. B. also by a capacitor discharge (DT-AS 12 90 003). Furthermore, the individual reading points can be simultaneously or can be controlled and queried in groups one after the other (DT-OS 23 20 574). The metallic information elements are usually full, flat plates. However, an arrangement of annular metallic surface elements is also known (P 2558917.7-53).

The known arrangements have the disadvantage that they are used for recognition the information require a relatively large reduction in the coupling magnetic flux and therefore metallic surface elements with comparatively large dimensions require.

In the case of a reading device, it is already known that the information element magnetically influenced scanning coil to be built into a bridge circuit, whereby a greater change in output voltage is achieved during sampling.

The invention is based on the object of a simple device of the type mentioned at the outset, which make reliable detection very small metallic information elements and which are characterized by greater sensitivity with regard to the perception of the information elements.

This object is achieved according to the invention by the in the characterizing part of claim 1 contained features solved.

Further developments of the invention are contained in the subclaims.

An exemplary embodiment is described below with reference to FIGS. 1-7.

The in F i g. 1 and F i g. 2 shown reading device consists from a housing 1 with a mouthpiece 2 for easy insertion of the card 3. In the reader, the card is fed between two circuit boards 4-1 and 4-2.

The information is recognized while the Map through the reading blocks 5-1 and 5-2 located close to the mouthpiece. The reading pads are made up of several, here twelve, reading units, each consisting of one Transmitting coil 6, a receiving coil 7 and a reference coil 8 exist.