GB2284324A - Antenna circuit for non-contact type portable storage device and method of manufacturing the same by trimming - Google Patents

Antenna circuit for non-contact type portable storage device and method of manufacturing the same by trimming Download PDF

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Publication number
GB2284324A
GB2284324A GB9500044A GB9500044A GB2284324A GB 2284324 A GB2284324 A GB 2284324A GB 9500044 A GB9500044 A GB 9500044A GB 9500044 A GB9500044 A GB 9500044A GB 2284324 A GB2284324 A GB 2284324A
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GB
United Kingdom
Prior art keywords
coil
antenna circuit
storage device
portable storage
conductive pattern
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.)
Granted
Application number
GB9500044A
Other versions
GB2284324B (en
GB9500044D0 (en
Inventor
Kenichi Takahira
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from JP3090323A external-priority patent/JPH04321190A/en
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Publication of GB9500044D0 publication Critical patent/GB9500044D0/en
Publication of GB2284324A publication Critical patent/GB2284324A/en
Application granted granted Critical
Publication of GB2284324B publication Critical patent/GB2284324B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
    • H01Q1/2225—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0723—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
    • G06K19/0726—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G06K19/0775—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card arrangements for connecting the integrated circuit to the antenna
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G06K19/07773—Antenna details
    • G06K19/07777—Antenna details the antenna being of the inductive type
    • G06K19/07779—Antenna details the antenna being of the inductive type the inductive antenna being a coil
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G06K19/07773—Antenna details
    • G06K19/07777—Antenna details the antenna being of the inductive type
    • G06K19/07779—Antenna details the antenna being of the inductive type the inductive antenna being a coil
    • G06K19/07783—Antenna details the antenna being of the inductive type the inductive antenna being a coil the coil being planar
    • 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
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Details Of Aerials (AREA)
  • Credit Cards Or The Like (AREA)

Abstract

Disclosed is an antenna circuit for a non-contact type portable storage device. The antenna circuit exchanges signals with an external device utilizing an electromagnetic wave. The antenna circuit includes a coil and a capacitor connected to the coil to form a resonant circuit. The coil includes a main coil having a spiral conductive pattern formed by trimming a pattern laid down on a peripheral portion of a substrate of the non-contact type portable storage device. Also disclosed are arrangements for selecting the number of active turns by trimming or switching. <IMAGE>

Description

A1JTENNA CIRCUIT FOR NON-CONTACT TYPE PORTABLE STORAGE DEVICE AND METHOD OF MANUFACTURING THE SAME BACKGROUND OF THE INVENTION FIELD OF THE INVENTION: The present invention relates to an antenna circuit for a non-contact type portable storage device and a method of manufacturing such an antenna circuit.
DESCRIPTION OF THE RELATED ART: Among the portable storage devices, such as IC cards, non-contact type portable storage devices designed to exchange signals using space transmission media, such as electromagnetic waves or light, have been used in recent years. Fig. 5 shows the configuration of such a non-contact type storage device. A ROM 2 and a RAM 3 are connected through a bus 8 to a CPU 1 for controlling the operation of the storage device. An input/output control circuit 4 for controlling input of data from and output of data to an external device (not shown) is connected to the bus 8. An antenna circuit 6 is connected to the input/output control circuit 4 through a modem circuit 5. A battery 7 is incorporated in the storage device for supplying power to the individual electric circuits in the storage device.
In such a storage device, a command signal received by the antenna circuit 6 from an external device, such as a terminal machine, in the form of an electromagnetic wave is demodulated by the modem circuit 5 and then input to the CPU 1 through the input/output control circuit 4. The CPU 1 decodes the command signal and creates a predetermined response signal. This response signal is input to the modem circuit 5 through the input/output control circuit 4 which modulates this signal. The modulated signal is transmitted to an external device from the antenna circuit 6.
In a practical storage device, as shown in Fig. 6, the CPU 1, the ROM 2, the RAM 3, the input/output control circuit 4, the modem circuit 5 and the bus 8 are fabricated in a single IC 9, and this IC 9 and the battery 7 are mounted on a card substrate 10. The antenna circuit 6 for exchanging signals with an external device using an electromagnetic wave has a coil 62 having an inductance L and consisting of a conductive pattern 61 formed in a spiral fashion on the peripheral portion of the card substrate 10, and a capacitor 63 having a capacitance C and fabricated on the card substrate 10. A combination of the coil 62 and the capacitor 63 forms an LC parallel resonant circuit which induces a voltage when it receives an electromagnetic wave of a frequency close to the resonant frequency, as shown in Fig. 7. Reception is made by detecting that induced voltage. In that case, the frequency of the electromagnetic waves that can be received by the antenna circuit 6 is determined by the resonant frequency fo = 1/{2X(L-C) 1/2} of the LC parallel resonant circuit.
As stated above, the coil 62 of the antenna circuit 6 is formed on the peripheral portion of the card substrate 10 in the form of a conductive pattern. Therefore, the inductance L of the coil 62 is determined at the time of manufacture of the card substrate 10, and a change of. the inductance L after the manufacture is impossible. Such an antenna circuit will not be used when the frequency of a carrier used for exchanging signals is changed.
Furthermore, matching of the resonant frequency cannot be sufficiently conducted after the card substrate 10 is manufactured.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an antenna circuit for a non-contact type portable storage device which is capable of coping with a change of the carrier frequency and of matching a resonant frequency after the circuit components are fabricated on a substrate.
Another-object of the present invention is to provide a method of manufacturing such an antenna circuit for a noncontact type portable storage device.
In order to achieve the above objects, according to one aspect of the present invention, there is provided an antenna circuit for a non-contact type portable storage device which comprises a coil and a capacitor connected to the coil to form a resonant circuit. The coil includes a main coil having a spiral conductive pattern formed on a peripheral portion of a substrate, and a plurality of adjusting patterns each of which electrically connects a portion of the conductive pattern corresponding to a desired number of turns of the main coil to one end of the main coil. The plurality of adjusting patterns are cut except for one adjusting pattern to obtain desired inductance characteristic.
According to another aspect of the present invention, there is provided an antenna circuit for a non-contact type portable storage device, which comprises a coil having a conductive pattern formed on a peripheral portion of a substrate, part of the conductive pattern being trimmed in a spiral fashion to obtain desired inductance characteristics of the coil, and a capacitor connected to the coil to form a resonant circuit.
According to another aspect of the present invention, there is provided an antenna circuit for a non-contact type portable storage device, which comprises a coil having a spiral conductive pattern formed on a peripheral portion of a substrate, a plurality of switches each of which is electrically connected between a portion of the conductive pattern corresponding to a desired number of turns of the coil to one end of the coil, and a capacitor connected to the other end of the coil to form a resonant circuit.
According to another aspect of the present invention, there is provided a method of manufacturing an antenna circuit for a non-contact type portable storage device, which comprises the steps of forming a main coil having a spiral conductive pattern on a peripheral portion of a substrate, forming on the substrate-a plurality of adjusting patterns each of which electrically connects a portion of the conductive pattern corresponding to a desired number of turns of the main coil to one end of the main coil, cutting the plurality of adjusting patterns except for one adjusting pattern to obtain desired inductance characteristics, and connecting a capacitor to the other end of the main coil to form a resonant circuit.
According to another aspect of the present invention, there is provided a method of manufacturing an antenna circuit for a non-contact type portable storage device, which comprises the steps of forming a conductive pattern on a peripheral portion of a substrate, forming a coil by trimming part of the conductive pattern in a spiral form while measuring an inductance of the conductive pattern until a desired inductance is obtained, and connecting one end of the coil to a capacitor to form a resonant circuit.
In the antenna circuit set forth in claim 1 of the present invention, a plurality of inductance characteristic adjusting patterns are provided. The inductance characteristics of the coil are adjusted by cutting the adjusting patterns except for one adjusting pattern.
In the antenna circuit set forth in claim 2 of the present invention, the inductance characteristics of the coil are adjusted by trimming part of the conductive pattern in a spiral form.
In the antenna circuit set forth in claim 3 of the present invention, the inductance characteristics of the coil are adjusted by turning on one of a plurality of switches while turning off the other switches.
In the manufacturing method set forth in claim 5 of the present invention, the adjusting patterns are cut except for one adjusting pattern to obtain an antenna circuit having desired characteristics.
In the manufacturing method set forth in claim 6 of the present invention, part of the conductive pattern is trimmed in a spiral form while the inductance of the conductive pattern is measured to obtain desired characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic plan view of a coil of a first embodiment of an antenna circuit for a non-contact type portable storage device according to the present invention; Fig. 2 is a schematic plan view of a coil of a second embodiment of the antenna circuit; Fig. 3 is a schematic plan view of a conductive pattern formed at the initial stage of the manufacturing process of the antenna circuit shown in Fig. 2; Fig .4 is a circuit diagram showing the configuration of a third embodiment of the antenna circuit according to the present invention; Fig. 5 is a block diagram of a conventional non-contact type portable storage device; Fig. 6 is a plan view showing the mechanical structure of the non-contact type portable storage device of Fig. 5; and Fig. 7 is a circuit diagram of an antenna circuit for the non-contact type portable storage device shown in Fig.
5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.
Fig. 1 shows a coil 11 of a first embodiment of an antenna circuit for a non-contact type portable storage device according to the present invention. Fig. 1 is a schematic view of the coil 11. Practically, the coil 11 is formed on the peripheral portion of a card substrate, while an IC and other components, such as a battery, are located on the inner side of the coil 11, as shown in Fig. 6. The coil 11 has a main coil 12 consisting of a conductive spiral pattern formed in three turns on the substrate in such a manner that it decreases in size as it approaches the center. A first adjusting pattern 13 for connecting a portion D at which the first turn intersects the second turn, as viewed from an end portion A of the main coil 12, to the other end portion B of the main coil 12 is formed on the substrate. A second adjusting pattern 14 for connecting a portion E at which the third turn terminates, as viewed from the end portion A of the main coil 12, to the other end portion B of the main coil 12 is formed on the rear surface of the substrate. The second adjusting pattern 14 is electrically connected to the main coil 12 via through-holes 16. A third adjusting pattern 15 for connecting a portion F at which the third turn terminates, as viewed from the end portion A of the main coil 12, to the other end portion B of the main coil 12 is formed on the rear surface of the substrate. This adjusting pattern 15 is electrically connected to the main coil 12 via through-holes 16.
The number of turns needed to form the coil 11 can be selected~from among one to three by cutting these three adjusting patterns 13 to 15 at a cutting line L1, L2 or L3 except for one adjusting pattern. For example, if the adjusting pattern 13 is left connected while the other adjusting patterns 14 and 15 are cut, a coil 11 having a single turn is provided. Similarly, if the adjusting pattern 14 is left connected, a coil 11 having two turns is provided. Leaving the adjusting pattern 15 connected provides a coil 11 having three turns.
Generally, a relationship, expressed by L = a N2, establishes between the inductance L of the coil and the number of turns N of the coil, where ffi is the constant determined by the shape of a coil. Therefore, the inductance L of the coil 11 can be adjusted by changing the number of turns of the coil 11.
A capacitor having a capacitance C is connected to the end portion A of the coil 11, as shown in Figs. 6 and 7.
This capacitor and the coil 11 in combination form an LC parallel resonant circuit which acts as an antenna circuit.
In this antenna circuit, even after the circuit components are built on the substrate, a change of the carrier frequency can be coped with and matching of the resonant frequency can be conducted by making a selection on the adjusting patterns 13 to 15.
Such an antenna circuit will be manufactured in the following manner: First, the main coil 12 consisting of the spiral conductive pattern is formed on the peripheral portion of the substrate, while the adjusting patterns for respectively connecting the portions D to F of the main coil 12 to the end portion B are formed. Next, the adjusting patterns 13 to 15 are cut except for any one of these patterns corresponding to a desired inductance. Cutting of the adjusting patterns is conducted by, for example, illumination of a laser beam to the pattern, cutting by means of sand or chemical etching. Thereafter, the capacitor is connected to the end portion A of the main coil 12 to form a resonant circuit. Connection of the capacitor to the end portion A of the main coil 12 may be conducted prior to the cutting of the adjusting patterns.
Although the main coil 12 having three turns is shown in Fig. 1, the number of turns of the coil is not limited to this. In a practical circuit, a main coil having a several tens of turns is used. Regrading this, the number of adjusting patterns is not limited to three but four or more adjusting patterns may be formed.
Fig. 2 shows a coil 17 of a second embodiment of an antenna circuit according to the present invention. Fig. 2 is a schematic view of the coil 17. Practically, the coil 17 is formed on the peripheral portion of a card substrate, while an IC and other components, such as a battery, are located on the inner side of the coil 17, as shown in Fig.
6. The coil 17 has a conductive pattern 18 formed on the substrate and partially trimmed in a spiral form. The innermost portion G of the conductive pattern 18 is electrically connected to an end portion pattern 21 formed on the surface of the substrate vig through-holes 19 and a connection pattern 20 formed on the rear surface of the substrate. The conductive pattern 18 is trimmed in a spiral form from position el to position e2. A number of turns of the coil 17 can be changed and the inductance characteristics of the coil 17 can thus be adjusted by changing the trimming ending portion e2. In Fig. 2, a dashed line indicates a pattern line for further trimming A capacitor having a capacitance C is connected to an end portion H or J, as shown in Figs. 6 and 7. This capacitor and the coil 17 in combination form an LC parallel resonant circuit which acts as an antenna circuit. In this embodiment, even after the circuit components are fabricated on the substrate,* a change in the carrier frequency can be coped with and matching of the resonant frequency can be conducted by further trimming the conductive pattern 18.
Such an antenna circuit will be manufactured in the manner described below. First, a wide ring-shaped conductive pattern 18 is formed on the peripheral portion of the substrate, as shown in Fig. 3, while the connection pattern 20 and the end portion pattern 21, connected to the portion G of the conductive pattern 18, are formed. Next, the conductive pattern 18 is trimmed in a spiral form starting from the position el while the inductance between the end portion H of the conductive pattern 18 and the end portion J of the end portion pattern 21 is measured using an inductance measuring device until a desired inductance value is obtained. At that time, trimming is conducted such that the width of the conductive pattern which is not trimmed is constant. As trimming proceeds, the number of turns of the coil 17 as viewed from the end portions H and J gradually increases, thus increasing the inductance L of the coil 17.
Trimming is ended when the desired inductance value has been obtained. Thereafter, the capacitor is connected to the end portion H of the conductive pattern 18 or to the end portion J to form a resonant circuit.
Connection of the capacitor may be conducted prior to trimming of the conductive pattern 18.
In this method of manufacturing the antenna circuit, since trimming of the conductive pattern 18 is conducted while measuring the inductance of the coil 17, the inductance can be adjusted with a very high degree of accuracy.
Fig. 4 shows a third embodiment of the antenna circuit according to the present invention. One end of a coil 22 having an inductance L is connected to one end of a capacitor 23 having a capacitance C to form an LC resonant circuit. The coil 22 is shaped in the form of a solenoid coil; Portions P, Q and R corresponding predetermined numbers of turns are connected to one end of switches S1, S2 and S3. The other ends of these switches Si, S2 and S3 are connected with each other and thereby form the other end of the coil 22.
By turning on one of the switches S1, S2 and S3 while turning off the other switches, the number of turns of the coil 22 can be selected from among three values. That is, by changing the switch to be turned on, the number of turns of the coil 22 can be changed. Consequently, the inductance of the resonant circuit can be adjusted.
The third embodiment may be implemented by forming a coil consisting of a spiral conductive pattern and a plurality of adjusting patterns on the peripheral portion of the substrate in a similar manner to that of the first embodiment shown in Fig. 1 and then by providing a switch for turning on and off the adjusting pattern on each adjusting pattern.
The switches S1, S2 and S3 may be a semiconductor analog switch Also, the number of switches is not limited to three.
In the third embodiment, on-off of the switches S1, S2 and S3 can be controlled by a control signal from a CPU (not shown) incorporated in the non-contact type portable storage device. That is, the essential inductance of the coil 22 can be changed in an application program by the program which controls the CPU.

Claims (4)

  1. A
    CLAIMS: 1. An antenna circuit for a non-contact type portable storage device, the antenna circuit exchanging signals with an external device utilizing an electromagnetic wave, the antenna circuit comprising: a coil having a conductive pattern formed on a peripheral portion of a substrate of said non-contact type portable storage device, part of said conductive pattern being trimmed in a spiral form to obtain desired inductance characteristics; and a capacitor connected to said coil to form a resonant circuit.
  2. 2. A method of manufacturing an antenna circuit for a non-contact type portable storage device, said method comprising the steps of: forming a conductive pattern on a peripheral portion of a substrate; forming a coil by trimming part ofthe conductive pattern in a spiral form while measuring an inductance ofthe conductive pattern until a desired inductance is obtained; and connecting one end ofthe coil to a capacitor to form a resonant circuit.
  3. 3. An antenna circuit for a non-contact portable storage device, substantially as herein described with reference to figures 2 and 3 ofthe accompanying drawings.
  4. 4. A method of manufacturing an antenna circuit for a non-contact portable storage device substantially as herein described with reference to figures 2 and 3 ofthe accompanying drawings.
GB9500044A 1991-04-22 1992-04-13 Method of manufacturing antenna circuit for non-contact type portable storage device Expired - Fee Related GB2284324B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP3090323A JPH04321190A (en) 1991-04-22 1991-04-22 Antenna circuit and its production for non-contact type portable storage
GB9208095A GB2255692B (en) 1991-04-22 1992-04-13 Antenna circuit for non-contact type portable storage device and method of manufacturing the same

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Publication Number Publication Date
GB9500044D0 GB9500044D0 (en) 1995-03-01
GB2284324A true GB2284324A (en) 1995-05-31
GB2284324B GB2284324B (en) 1995-10-04

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GB9500070A Expired - Fee Related GB2284325B (en) 1991-04-22 1992-04-13 Antenna circuit for non-contact type portable storage device
GB9500044A Expired - Fee Related GB2284324B (en) 1991-04-22 1992-04-13 Method of manufacturing antenna circuit for non-contact type portable storage device

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2744863A1 (en) * 1996-02-13 1997-08-14 Schlumberger Ind Sa METHOD FOR PRODUCING A PORTABLE OBJECT WITH A COILED ANTENNA

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5065780B2 (en) 2007-07-03 2012-11-07 株式会社日立製作所 RFID tag mounting board

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Publication number Priority date Publication date Assignee Title
US4494100A (en) * 1982-07-12 1985-01-15 Motorola, Inc. Planar inductors
EP0149240A2 (en) * 1983-12-27 1985-07-24 Polyonics Corporation Resonant tag circuits useful in electronic security systems
GB2207289A (en) * 1987-06-30 1989-01-25 H R Smith Forming metal film patterns on substrates

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Publication number Priority date Publication date Assignee Title
US4021705A (en) * 1975-03-24 1977-05-03 Lichtblau G J Resonant tag circuits having one or more fusible links

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4494100A (en) * 1982-07-12 1985-01-15 Motorola, Inc. Planar inductors
EP0149240A2 (en) * 1983-12-27 1985-07-24 Polyonics Corporation Resonant tag circuits useful in electronic security systems
GB2207289A (en) * 1987-06-30 1989-01-25 H R Smith Forming metal film patterns on substrates

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2744863A1 (en) * 1996-02-13 1997-08-14 Schlumberger Ind Sa METHOD FOR PRODUCING A PORTABLE OBJECT WITH A COILED ANTENNA
EP0790667A1 (en) * 1996-02-13 1997-08-20 Schlumberger Industries Method for realisation of a portable object with a coil antenna

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Publication number Publication date
GB2284325A (en) 1995-05-31
GB9500070D0 (en) 1995-03-01
GB2284324B (en) 1995-10-04
GB2284325B (en) 1995-09-27
GB9500044D0 (en) 1995-03-01

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Effective date: 19980413