WO1986002186A1 - Identification system - Google Patents

Identification system Download PDF

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Publication number
WO1986002186A1
WO1986002186A1 PCT/SE1985/000368 SE8500368W WO8602186A1 WO 1986002186 A1 WO1986002186 A1 WO 1986002186A1 SE 8500368 W SE8500368 W SE 8500368W WO 8602186 A1 WO8602186 A1 WO 8602186A1
Authority
WO
WIPO (PCT)
Prior art keywords
frequencies
abovementioned
unit
frequency
transmitter unit
Prior art date
Application number
PCT/SE1985/000368
Other languages
French (fr)
Inventor
Bengt Larsson
Original Assignee
Saab Automation Ab
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
Application filed by Saab Automation Ab filed Critical Saab Automation Ab
Publication of WO1986002186A1 publication Critical patent/WO1986002186A1/en

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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
    • 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
    • G06K19/0672—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 resonating marks
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/20—Individual registration on entry or exit involving the use of a pass
    • G07C9/28—Individual registration on entry or exit involving the use of a pass the pass enabling tracking or indicating presence

Definitions

  • the present invention is a system for identifying objects by means of an identification tag which is attached to them. Identification is carried out by using radio frequency electromagnetic waves from a transmitter, which are detected by a sensor unit.
  • the identification tag contains electrical resonance circuits tuned to various frequencies within the work area of the transmitter.
  • radio frequency electromagnetic waves to detect resonance cir ⁇ cuits is already known.
  • Such systems are used, for example, to detect theft in department stores, where a tag containing a resonance circuit is attached to the goods to be protected against theft. If an item with a tag attached is carried through a passage equipped with transmitters and sensor elements, a tag containing a resonance circuit is detected and an alarm sounds.
  • the American patent specification 3,671,721 describes a system for read ⁇ ing data from identification tags containing several different circuits.
  • circuits tuned to three different frequencies are placed in columns. By exciting these different frequencies with an oscillator, the frequencies that load the oscillator are detected.
  • the circuits in the adjacent columns are tuned to different frequencies to prevent them from interfering with the scan.
  • alternate columns are tuned to the three first frequencies, while the other columns are tuned to three dif ⁇ ferent frequencies.
  • This device which is already known, has the major drawback that the circuits can only be detected at close range and the sensors are er sensitive to the position of the circuits. If, for example, a tag is inverted, the reading it gives will be completely wrong.
  • the purpose of the present invention is to create an identification sys ⁇ tem to be attached to the objects to be identified, each identification tag containing electrical resonance circuits tuned to different resonance frequencies. These must be possible to detect by a sensor unit, both at considerable distances and irrespective of the position of the iden ⁇ tification tag. This means that it must be possible to place the iden ⁇ tification tag in any position without causing errors in recognition.
  • the invention solves these problems in the way described in the appended Patent Claim 1.
  • the basis of this claim is that an identification tag is fitted either to the outside or inside of the object to be identified, and that this tag contains resonance circuits tuned to various frequencies. Radio frequency electromagnetic waves are transmitted from an antenna in such a way that the waves reach the identification tag.
  • a sensor element is connected to a-second, or possibly the same, antenna.
  • each identification tag con ⁇ tains a predetermined number of resonance circuits, tuned to one or more frequencies selected from a given set of frequencies, and that the trans ⁇ mitter unit emits radio frequency signals with a frequency content cor ⁇ responding exactly to each and one of the choice of resonance frequencies from the abovementioned set of frequencies.
  • the signal transmitted consists of a pulse sequence with a predetermined number of pulses with a fixed fundamental frequency, where the pulse length and interval and the abovementioned fixed fundamental frequency have been chosen so that the pulse sequence's Fourier spectrum produces frequencies that correspond to the different frequencies in the abovementioned set of frequencies.
  • the rise and fall times of the pulses must be the same as, or shorter than, the fundamental frequency period.
  • the signal transmitted is of very short duration and is terminated very abruptly.
  • the sensor unit is de-activated, this block being so arranged that it is removed immediately after the abrupt termination of the transmitted signal. All the resonance circuits in the identification tag will then, after being excited by the respec ⁇ tive Fourier component's frequencies, self-oscillate even after the ex ⁇ citation signal has ceased.
  • the sensor unit By equipping the sensor unit with the same number of band-pass circuits as the different self-osci 11 ating frequencies in the identification tag or by scanning in discrete stages over the frequency band in question, the sensor unit can rapidly detect the presence or absence of certain frequencies. This information constitutes the basis for generating data that will explicitly give the number or corresponding code of the identification tag in question.
  • the transmitter and receiver scan in discrete stages over the entire frequency band. If the decay time of the resonance circuits is shorter than the scanning time, the transmitter scan may suitably be divided in a way that will avoid the signal level in the self-oscillating circuits dropping close to the noise level. The transmitter unit then retransmits signals which are detected by the receiver. While the transmitter is in operation, and shortly before and after each transmission, the input of the sensor unit is blocked.
  • the local oscillator of the receiver may suitably be used as the master oscillator of the transmitter and generate the different frequencies by using an offset oscillator linked to the receiver.
  • the transmitter unit antenna may also be arranged so that the object to be identified is made to pass through a closed antenna loop.
  • the transmitter units feeds to frame- formed sub-antennas both of which enclose the path of the object to be identified; these two frame antenna being set at a certain angle to each other. This configuration prevents the occurrence of dead -zones, i.e. zones in which the signal strength at the polarization in question is so weak that detection becomes impossible or uncertain.
  • figure 1 shows a device using known technology
  • figure 2 shows a device for applying this invention to identify par- eels on a conveyer belt
  • figure 3 shows a time sequence for transmitting and detecting as per this invention
  • figure 4 shows a transmission pulse in detail
  • figure 5 shows the frequency content of a typical transmission pulse
  • figure 6 finally shows a possible antenna configuration.
  • the application shown in figure 1 is based on an arrangement of resonance circuits in the form of open spirals at predetermined places.
  • This card thus has 6 columns, in each of which three resonance circuits may be placed.
  • the resonance frequencies of these resonance circuits vary in each column, where three different frequencies can occur.
  • the frequency content of the circuits in the adjacent columns have been arranged to avoid cross talk causing any collision of frequencies.
  • By using a detec ⁇ tor cable to scan column by column the frequencies that occur in a given column may be identified.
  • the frequencies that are detected are compared with predetermined frequencies, and this comparison gives a binary code for each column.
  • the problem in using this type of scanning is that in certain situations it may be difficult or unsuitable to use a sensor unit and circuits with resonance frequencies as close to each other as this system requires.
  • Another disadvantage is that detection is extremely sensitive to position, which can cause scanning errors or other problems.
  • FIG. 2 shows a system according to this invention, in which an object (1), for example a parcel, is transported on a conveyer belt (7).
  • This belt passes through two enclosed antenna loops which are connected to an electronic unit containing a transmitting unit (3) and a sensor unit (4).
  • the two antenna loops (5 and 6) are placed so that they can both detect the direction of the objects that are passing and also prevent any dead zones in which detection is not possible.
  • Attached to an object (1) is an identification tag (2) containing resonance circuits tuned to dif ⁇ ferent frequencies.
  • the transmitter (3) excites these resonance circuits and when the signal transmitted abruptly ceases, the resonance circuits continue to oscillate for a period, during which time the frequencies are detected by using the same antenna configuration to which the sensor unit is connected.
  • the frequency content gives a code that may be presented for example in alphanumeric form on a display (8).
  • the identification tag (2) need not be attached to the outside of the object (1) but may also be placed inside the object. The important factor is that the iden ⁇ tification tag (2) passes through the closed antenna loops (5 and 6).
  • Figure 3 shows a practical time diagram of/the sequence of transmission and detection.
  • the transmitter emits radio frequency electromagnetic waves.
  • either one of the frequencies contained in the frequency spectrum can be trans ⁇ mitted at a time, with reception immediately following each transmission, or each transmission can emit all or a certain proportion of the fre ⁇ quencies in the set of frequencies.
  • the result will be that all of the resonance circuits in the identification tag will be excited.
  • the transmission abruptly ceases by shorting the output over a suitable resistance, the sensor unit being activated shortly afterwards. Detection then takes place while the resonance circuits are oscillating.
  • frequency scanning can be done by means of parallel detection with the aid of several band-pass circuits set at the predetermined frequencies.
  • FIG 4 is a more detailed diagram of a transmitter pulse according to the first design of the invention.
  • the transmitted pulse starts at time t " - and continues until time t .
  • the transmitter pulse envelope is shown as a shaded area.
  • the transmitter pulse thus consists of several identi ⁇ cal sub-pulses 12, 13, 14, 15, 16, in the form of sine oscillations at the frequency f-.
  • the pulse length and pulse interval and the frequency of the pulses f 0 thus determines the Fourier spectrum of the pulse train.
  • Figure 5 shows a typical Fourier spectrum of this kind. It may be ob ⁇ served that there are a number of frequencies, and that they are located in mirror image symmetry around the fundamental frequency. The dif ⁇ ference in frequency between adjacent frequencies can be made constant f, but this is not essential. The different sub-frequencies will then cause the resonance circuits that are tuned to the sub-frequency in ques ⁇ tion to oscillate.
  • FIG. 6 shows a possible antenna configuration.
  • the antennas here con ⁇ sist of two closed loops (5 and 6). In these loops, either the transmit ⁇ ter or the receiver coil windings have, been divided into two separate systems. These two closed circuits can either be connected so that their fields counteract each other, or so that the fields interact.
  • the second loop in the field is connected to the abovementioned second function, i.e. if the transmitter unit is connected with the unbroken lines, the receiver unit is connected with the broken lines.
  • the different resonance cir ⁇ cuits are excited sequentially, the transmitter unit transmitting fixed frequencies controlled by the same master oscillator that controls the receiver.
  • the signal sequences do not need to be in any particular order or of any particular length, but the pulses should cease abruptly.
  • the tuning of the dif ferent resonance circuits in the identification tags may suitably be carried out by a programming unit. In this way it will address the ob ⁇ ject to which the identification tag is attached.
  • the device that is the subject of the present invention may be used, for example, for marking goods, addressing letters, marking patients in hospitals, or for conventional identification tags to allow access and exit.

Abstract

Device for identifying objects (1) to which identification tags (2) have been attached. Identification is carried out with the aid of radio frequency electromagnetic waves. The device consists of a transmitter (3) and a sensor unit (4), each connected to a separate or common antenna (5 and 6) and where the abovementioned identification tags contain electronic resonance circuits tuned to predetermined resonance frequencies. The invention is characterised by each identification tag (2) containing one or more resonance circuits, each tuned to a different frequency, where each of these frequencies is selected from a given set of frequencies, and that the transmitter unit (4) transmits radio frequency signals with a frequency content corresponding to each of the frequencies contained in the abovementioned set of predetermined frequencies.

Description

Identification system
The present invention is a system for identifying objects by means of an identification tag which is attached to them. Identification is carried out by using radio frequency electromagnetic waves from a transmitter, which are detected by a sensor unit. The identification tag contains electrical resonance circuits tuned to various frequencies within the work area of the transmitter.
The use of radio frequency electromagnetic waves to detect resonance cir¬ cuits is already known. Such systems are used, for example, to detect theft in department stores, where a tag containing a resonance circuit is attached to the goods to be protected against theft. If an item with a tag attached is carried through a passage equipped with transmitters and sensor elements, a tag containing a resonance circuit is detected and an alarm sounds.
The American patent specification 3,671,721 describes a system for read¬ ing data from identification tags containing several different circuits. In this device, circuits tuned to three different frequencies are placed in columns. By exciting these different frequencies with an oscillator, the frequencies that load the oscillator are detected. The circuits in the adjacent columns are tuned to different frequencies to prevent them from interfering with the scan. Thus, alternate columns are tuned to the three first frequencies, while the other columns are tuned to three dif¬ ferent frequencies. This device, which is already known, has the major drawback that the circuits can only be detected at
Figure imgf000003_0001
close range and the sensors are er sensitive to the position of the circuits. If, for example, a tag is inverted, the reading it gives will be completely wrong.
The purpose of the present invention is to create an identification sys¬ tem to be attached to the objects to be identified, each identification tag containing electrical resonance circuits tuned to different resonance frequencies. These must be possible to detect by a sensor unit, both at considerable distances and irrespective of the position of the iden¬ tification tag. This means that it must be possible to place the iden¬ tification tag in any position without causing errors in recognition. The invention solves these problems in the way described in the appended Patent Claim 1. The basis of this claim is that an identification tag is fitted either to the outside or inside of the object to be identified, and that this tag contains resonance circuits tuned to various frequencies. Radio frequency electromagnetic waves are transmitted from an antenna in such a way that the waves reach the identification tag. A sensor element is connected to a-second, or possibly the same, antenna.
A characteristic of the invention is that each identification tag con¬ tains a predetermined number of resonance circuits, tuned to one or more frequencies selected from a given set of frequencies, and that the trans¬ mitter unit emits radio frequency signals with a frequency content cor¬ responding exactly to each and
Figure imgf000004_0001
one of the choice of resonance frequencies from the abovementioned set of frequencies. In one design of the invention, the signal transmitted consists of a pulse sequence with a predetermined number of pulses with a fixed fundamental frequency, where the pulse length and interval and the abovementioned fixed fundamental frequency have been chosen so that the pulse sequence's Fourier spectrum produces frequencies that correspond to the different frequencies in the abovementioned set of frequencies. If this is to function satisfactorily, the rise and fall times of the pulses must be the same as, or shorter than, the fundamental frequency period. In the invention, the signal transmitted is of very short duration and is terminated very abruptly. During the transmission of the signal, the sensor unit is de-activated, this block being so arranged that it is removed immediately after the abrupt termination of the transmitted signal. All the resonance circuits in the identification tag will then, after being excited by the respec¬ tive Fourier component's frequencies, self-oscillate even after the ex¬ citation signal has ceased. By equipping the sensor unit with the same number of band-pass circuits as the different self-osci 11 ating frequencies in the identification tag or by scanning in discrete stages over the frequency band in question, the sensor unit can
Figure imgf000005_0001
rapidly detect the presence or absence of certain frequencies. This information constitutes the basis for generating data that will explicitly give the number or corresponding code of the identification tag in question.
In a different version of the invention, the transmitter and receiver scan in discrete stages over the entire frequency band. If the decay time of the resonance circuits is shorter than the scanning time, the transmitter scan may suitably be divided in a way that will avoid the signal level in the self-oscillating circuits dropping close to the noise level. The transmitter unit then retransmits signals which are detected by the receiver. While the transmitter is in operation, and shortly before and after each transmission, the input of the sensor unit is blocked. In this variation of the invention, the local oscillator of the receiver may suitably be used as the master oscillator of the transmitter and generate the different frequencies by using an offset oscillator linked to the receiver.
The transmitter unit antenna may also be arranged so that the object to be identified is made to pass through a closed antenna loop. In an advan¬ tageous form of the invention, the transmitter units feeds to frame- formed sub-antennas both of which enclose the path of the object to be identified; these two frame antenna being set at a certain angle to each other. This configuration prevents the occurrence of dead -zones, i.e. zones in which the signal strength at the polarization in question is so weak that detection becomes impossible or uncertain.
The invention is described in detail blow, referring to the appended diagrams 1-6 where:
figure 1 shows a device using known technology figure 2 shows a device for applying this invention to identify par- eels on a conveyer belt figure 3 shows a time sequence for transmitting and detecting as per this invention, figure 4 shows a transmission pulse in detail, figure 5 shows the frequency content of a typical transmission pulse and figure 6 finally shows a possible antenna configuration.
The application shown in figure 1 is based on an arrangement of resonance circuits in the form of open spirals at predetermined places. This card thus has 6 columns, in each of which three resonance circuits may be placed. The resonance frequencies of these resonance circuits vary in each column, where three different frequencies can occur. The frequency content of the circuits in the adjacent columns have been arranged to avoid cross talk causing any collision of frequencies. By using a detec¬ tor cable to scan column by column, the frequencies that occur in a given column may be identified. The frequencies that are detected are compared with predetermined frequencies, and this comparison gives a binary code for each column. The problem in using this type of scanning is that in certain situations it may be difficult or unsuitable to use a sensor unit and circuits with resonance frequencies as close to each other as this system requires. Another disadvantage is that detection is extremely sensitive to position, which can cause scanning errors or other problems.
Figure 2 shows a system according to this invention, in which an object (1), for example a parcel, is transported on a conveyer belt (7). This belt passes through two enclosed antenna loops which are connected to an electronic unit containing a transmitting unit (3) and a sensor unit (4). The two antenna loops (5 and 6) are placed so that they can both detect the direction of the objects that are passing and also prevent any dead zones in which detection is not possible. Attached to an object (1) is an identification tag (2) containing resonance circuits tuned to dif¬ ferent frequencies. The transmitter (3) excites these resonance circuits and when the signal transmitted abruptly ceases, the resonance circuits continue to oscillate for a period, during which time the frequencies are detected by using the same antenna configuration to which the sensor unit is connected. The frequency content gives a code that may be presented for example in alphanumeric form on a display (8). The identification tag (2) need not be attached to the outside of the object (1) but may also be placed inside the object. The important factor is that the iden¬ tification tag (2) passes through the closed antenna loops (5 and 6).
Figure 3 shows a practical time diagram of/the sequence of transmission and detection. During the time interval t-, - t2 the transmitter emits radio frequency electromagnetic waves. During these transmissions either one of the frequencies contained in the frequency spectrum can be trans¬ mitted at a time, with reception immediately following each transmission, or each transmission can emit all or a certain proportion of the fre¬ quencies in the set of frequencies. The result, however, will be that all of the resonance circuits in the identification tag will be excited. At t2 the transmission abruptly ceases by shorting the output over a suitable resistance, the sensor unit being activated shortly afterwards. Detection then takes place while the resonance circuits are oscillating. If detection is sequential, thus requiring a certain amount of time, it may be appropriate to detect some of the frequency content at the first scan, the detector unit then being blocked while the next pulse is transmitted, followed by re-activation of the sensor unit and a continued frequency scan. This naturally requires the identification tag and resonance circuits to be in the field from the antenna loops for a suffi¬ cient period of time, which does not normally constitute a problem when handling physical objects. Alternatively, frequency scanning can be done by means of parallel detection with the aid of several band-pass circuits set at the predetermined frequencies.
Figure 4 is a more detailed diagram of a transmitter pulse according to the first design of the invention. The transmitted pulse starts at time t"- and continues until time t . The transmitter pulse envelope is shown as a shaded area. The transmitter pulse thus consists of several identi¬ cal sub-pulses 12, 13, 14, 15, 16, in the form of sine oscillations at the frequency f-. The pulse length and pulse interval and the frequency of the pulses f0 thus determines the Fourier spectrum of the pulse train.
Figure 5 shows a typical Fourier spectrum of this kind. It may be ob¬ served that there are a number of frequencies, and that they are located in mirror image symmetry around the fundamental frequency. The dif¬ ference in frequency between adjacent frequencies can be made constant f, but this is not essential. The different sub-frequencies will then cause the resonance circuits that are tuned to the sub-frequency in ques¬ tion to oscillate.
Figure 6 shows a possible antenna configuration. The antennas here con¬ sist of two closed loops (5 and 6). In these loops, either the transmit¬ ter or the receiver coil windings have, been divided into two separate systems. These two closed circuits can either be connected so that their fields counteract each other, or so that the fields interact. The second loop in the field is connected to the abovementioned second function, i.e. if the transmitter unit is connected with the unbroken lines, the receiver unit is connected with the broken lines. By having the antenna divided into two coils, it is possible to both detect the direction of movement and also create a field configuration that eliminates all dead zones.
In an alternative design for this invention, the different resonance cir¬ cuits are excited sequentially, the transmitter unit transmitting fixed frequencies controlled by the same master oscillator that controls the receiver. The signal sequences do not need to be in any particular order or of any particular length, but the pulses should cease abruptly.
When using the system according to this invention, the tuning of the dif ferent resonance circuits in the identification tags may suitably be carried out by a programming unit. In this way it will address the ob¬ ject to which the identification tag is attached.
The device that is the subject of the present invention may be used, for example, for marking goods, addressing letters, marking patients in hospitals, or for conventional identification tags to allow access and exit.

Claims

PATENT CLAIM
1. A device for identifying objects (1) to which identification tags (2) have been attached, by using radio frequency electromagnetic waves. The device consists of a transmitter unit (3) and a sensor unit (4) each con¬ nected to its own antenna, or a common antenna (5,6) and when the abovementioned identification tag (2) containing electrical resonance circuits tuned to predetermined resonance frequencies, characterised by each identification tag (2) containing one or more resonance circuits, each tuned to a different frequency, each of these abovementioned frequencies being selected from a set of frequencies and that the trans¬ mitter unit (4) emits radio frequency signals with a frequency content corresponding to each of the frequencies contained in the given set of frequencies.
2. A device according to claim 1, characterised by a transmitter unit (4) transmitting pulses in sequence, in which each pulse has a given frequency, until all frequencies in a given frequency spectrum have been transmitted, and by a receiver being activated during the time intervals between the abovementioned pulses.
3. A device according to claim 1, characterised by a transmitter unit (4) during the same transmission interval, transmitting frequencies vary¬ ing in time, comprising all or only some of the frequencies included in the abovementioned set of frequencies.
4. A device according to claim 1, characterised by a transmitter unit (4) .transmitting sequence pulses at the same frequency during one and the same transmission interval, but with a pulse length and pulse interval that causes the pulse sequence's Fourier spectrum to cover all the frequencies included in the abovementioned set of frequencies.
5. A device according to one of the claims 1-5, characterised by a receiver unit (3) input being shorted during the transmission from the transmitter unit (4) and that the receiving unit's local oscillator is used as the oscillator in the transmitter unit.
PCT/SE1985/000368 1984-09-28 1985-09-26 Identification system WO1986002186A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8404876A SE8404876L (en) 1984-09-28 1984-09-28 IDENTIFICATION SYSTEM
SE8404876-8 1984-09-28

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WO1986002186A1 true WO1986002186A1 (en) 1986-04-10

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Cited By (20)

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Publication number Priority date Publication date Assignee Title
WO1989005984A1 (en) * 1987-12-23 1989-06-29 Schweizerische Aluminium Ag Process for adapting the frequency band of an oscillating circuit made from a metal-plastic-metal sandwich foil useful as an identification label, and sandwich foil for implementing the process
US5113183A (en) * 1987-06-16 1992-05-12 Casio Computer Co., Ltd. Remote code transmission system between a nameplate apparatus and a data processing apparatus
EP0494764A1 (en) * 1991-01-09 1992-07-15 Texas Instruments Incorporated Interrogation station for the identification of objects moved along a conveyor
EP0496611A1 (en) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Antenna system for an interrogating station for the identification of objects
EP0496610A2 (en) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Interrogating station for identification purposes, with separate transmitting and receiving antennae
EP0496609A1 (en) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Interrogating station for objects to be identified
US5140581A (en) * 1989-01-18 1992-08-18 Bell & Howell Phillipsburg Co. Read window for envelope reader
GB2259631A (en) * 1991-09-13 1993-03-17 Fluoroware Inc A device for identifying a person or object
FR2683951A1 (en) * 1991-11-14 1993-05-21 Michelin & Cie ANTENNA STRUCTURE SUITABLE FOR COMMUNICATION WITH AN ELECTRONIC LABEL IMPLANTED IN A TIRE.
EP0545910A2 (en) 1987-12-23 1993-06-09 Alusuisse-Lonza Services Ag Laminated foil for making high-frequency field interfering elements
WO1993013500A1 (en) * 1991-12-31 1993-07-08 Privates Institut Für Physikalisch Technische Auftragsforschung Gmbh Process for recording intermediate and final times in sporting events
US5381137A (en) * 1992-10-26 1995-01-10 Motorola, Inc. RF tagging system and RF tags and method
WO1995014938A1 (en) * 1993-11-26 1995-06-01 Magellan Technology Pty. Ltd. Location apparatus and method
WO1995028748A1 (en) * 1994-04-18 1995-10-26 Finlayson, Dorothy, Elizabeth Antenna arrangement
US5604486A (en) * 1993-05-27 1997-02-18 Motorola, Inc. RF tagging system with multiple decoding modalities
US5696481A (en) * 1991-12-31 1997-12-09 Pejas; Wolfram Process for recording intermediate and final times in sporting events
WO2001037004A1 (en) * 1999-11-15 2001-05-25 Bluetags A/S An object detection system
EP0677752B1 (en) * 1994-04-15 2001-06-27 Siemens Aktiengesellschaft Sensor System
US6624752B2 (en) 1999-11-15 2003-09-23 Bluetags A/S Object detection system
JP2018097666A (en) * 2016-12-14 2018-06-21 トッパン・フォームズ株式会社 Reading device and reading method

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US4023167A (en) * 1975-06-16 1977-05-10 Wahlstrom Sven E Radio frequency detection system and method for passive resonance circuits
US4069472A (en) * 1975-12-25 1978-01-17 Tokyo Shibaura Electric Co., Ltd. Foreground subject-identifying apparatus
US4209783A (en) * 1977-03-30 1980-06-24 Tokyo Shibaura Electric Co., Ltd. Object identification system
US4458235A (en) * 1980-02-27 1984-07-03 Tokyo Shibaura Denki Kabushiki Kaisha Foreground subject-identifying apparatus

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US3363247A (en) * 1967-05-05 1968-01-09 Gen Electric Identification system
US4023167A (en) * 1975-06-16 1977-05-10 Wahlstrom Sven E Radio frequency detection system and method for passive resonance circuits
US4069472A (en) * 1975-12-25 1978-01-17 Tokyo Shibaura Electric Co., Ltd. Foreground subject-identifying apparatus
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US4458235A (en) * 1980-02-27 1984-07-03 Tokyo Shibaura Denki Kabushiki Kaisha Foreground subject-identifying apparatus

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5113183A (en) * 1987-06-16 1992-05-12 Casio Computer Co., Ltd. Remote code transmission system between a nameplate apparatus and a data processing apparatus
WO1989005984A1 (en) * 1987-12-23 1989-06-29 Schweizerische Aluminium Ag Process for adapting the frequency band of an oscillating circuit made from a metal-plastic-metal sandwich foil useful as an identification label, and sandwich foil for implementing the process
EP0545910A2 (en) 1987-12-23 1993-06-09 Alusuisse-Lonza Services Ag Laminated foil for making high-frequency field interfering elements
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