EP0464186A1 - Procede et dispositif pour l'analyse des informations d'un support de code - Google Patents

Procede et dispositif pour l'analyse des informations d'un support de code

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Publication number
EP0464186A1
EP0464186A1 EP19910903419 EP91903419A EP0464186A1 EP 0464186 A1 EP0464186 A1 EP 0464186A1 EP 19910903419 EP19910903419 EP 19910903419 EP 91903419 A EP91903419 A EP 91903419A EP 0464186 A1 EP0464186 A1 EP 0464186A1
Authority
EP
European Patent Office
Prior art keywords
code carrier
code
field
magnetic
carrier
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.)
Withdrawn
Application number
EP19910903419
Other languages
German (de)
English (en)
Inventor
Kurt Wally
Roland GRÖSSINGER
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of EP0464186A1 publication Critical patent/EP0464186A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; 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
    • G06K7/087—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 flux-sensitive, e.g. magnetic, detectors
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; 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
    • G06K19/06187—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 with magnetically detectable marking

Definitions

  • the invention relates to a code carrier for evaluating a code for identifying products, which code carrier is arranged under a cover layer and consists of magnetic, magnetizable and / or electrically conductive material, and to a method for evaluating the information of one of them Cover layer of a product arranged code carrier, in which the code carrier consists of magnetic, magnetizable and / or electrically conductive material and has a geometric configuration containing the code. Furthermore, the invention relates to a coding system for labeling products
  • At least one code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as Recesses, breakthroughs and / or cross section changing over an axis of the code carrier
  • at least one field source at least one field source
  • at least one field sensor for measuring the stray field caused by the code carrier
  • code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as recesses, openings and / or cross-section changing over an axis of the code carrier, for evaluating the stray field which forms in an electromagnetic field for identification purposes ⁇ Drawing of the product by the code carrier arranged under a cover layer of the product.
  • code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as recesses, openings and / or cross-section changing over an axis of the code carrier, for evaluating the stray field which forms in an electromagnetic field for identification purposes ⁇ Drawing of the product by the code carrier arranged under a cover layer of the product.
  • a complete monitoring of a product means that the product is provided with an appropriate marking or coding, if possible at the beginning of its manufacture. This marking can then be read and logged at every production step. For example, it is possible to register the time of the individual manufacturing steps of each product. This enables a cost optimization of the manufacturing process.
  • Barcode is a simple, optically readable line pattern. This type of coding is used on a large scale today to identify mass products in sales. In the manufacture of products, however, problems arise when reading the bar code because it is contaminated, or the bar code is covered during manufacture, or is also destroyed by a processing operation.
  • Electronic marking systems consist of an electronic logic circuit into which information can be read or read without contact, for example via infrared, or inductively can be.
  • Chip cards which are used for high-security systems, but also for production monitoring.
  • the information is in a programmable memory chip which can then be read in and read out via high-frequency systems.
  • This is an intelligent system that is very versatile.
  • the disadvantage arises that such systems are too expensive for production with large quantities.
  • the chip can therefore never be permanently integrated into the product. In most cases, the chip would not be able to withstand the production process due to thermal and mechanical loads. This system is therefore not sufficiently robust.
  • a magnetoresistive converter device for reading out coded information for franking machines is known.
  • the code is implemented by the known change in an electrical resistance in a magnetic field (“magnetoresistance”), the arrangement of magnetoresistors and so-called soft-magnetic focusing units representing the code.
  • the shape of the code carrier and its magnetization play no role here.
  • a disadvantage of this system is that, owing to its arrangement and its space requirement, it is not suitable for coding mass products. The measurement of the magnetoresistance is also hardly possible without contact.
  • the magnetic code is implemented by an arrangement of permanent magnets, the code being represented by the north or south poles.
  • the geometrical shape of the magnets plays no role in this system.
  • the reading elements consist of Hall elements, which allow the north or south pole to be recognized by the voltage supplied. The given here This Hall voltage is very dependent on the distance and decreases approximately with the third power of the distance, so that a measurement only gives reproducible statements if the distance tolerances are kept to a close margin.
  • the magnets can also not be arranged very close to one another, since they would otherwise influence one another.
  • Such modules, which contain permanent magnets are neither cheap to manufacture nor easy to integrate into any mass product.
  • a similar electronic system for acquiring binary data on workpieces on a transfer line is known from DE-Al-33 31 694.
  • the code information is written into a so-called EPROM (erasable memory component).
  • An inductively operating system consisting of a special transformer, serves both for the energy supply of the EPROM and for data transmission.
  • the disadvantage here is that the use of an EPROM is both too expensive for many mass-produced products and that the environmental conditions existing during manufacture, for example pressure, temperature or the like, would destroy the EPROM.
  • the use of an active component as a code memory also makes an energy supply necessary in principle, which leads to significant restrictions.
  • DE-Al-27 12 016 discloses a method and a device for detecting and identifying objects provided with coded labels.
  • the aim of this known prior art is to facilitate the automatic sorting of packages and mail bags.
  • the code consists of thin magnetic strips or wires.
  • the code is realized by dividing these magnetic strips or by grouping together several such magnetic strips. Another possibility is to use materials with different coercive field strengths. Another disadvantage is that this code can hardly be produced so inexpensively in terms of production technology that it can be mass-produced. products is usable.
  • the known reading unit consists of an AC excitation coil, which can also have Helmholtz geometry in a known manner in order to generate a more homogeneous field.
  • the code is detected with the aid of balanced detector coils by measuring the voltage amplitudes resulting from induction, or phase shifts, in the case of code materials with different hysteresis loops.
  • the measured signal depends on the speed of the moving object. It is therefore
  • DE-Al-24 37 547 discloses a method for displaying and evaluating a digital code applied to a carrier with ferro-magnetic material.
  • the code is produced by intermeshing, ferromagnetic strips or strip groups.
  • the disadvantage here is that the manufacturing implementation of this code carrier for mass products is too complicated. The presence
  • AT-PS 309 111 From AT-PS 309 111 it is known to attach a ferromagnetic carrier to a body to be identified and to magnetically code it from a distance in order to read the code with a reading head. Such a method can be based on
  • skis are covered with markings that become visible under UV radiation. to press.
  • markings that become visible under UV radiation. to press.
  • This marking is deleted in certain processing steps, such as grinding or normal wear, as is also the case with the use of so-called barcodes, which is customary for product identification.
  • an inexpensive coding system that is and remains firmly attached to each individual product would be desirable. It is also advantageous if the coding element is covered in the product, i.e. not directly visible or at least protected under a cover layer. This also allows the "career" of the product to be checked after its sale, which e.g. in warranty cases but also underwriting, for example in the event of theft, can be advantageous.
  • the invention now aims to provide a code carrier of the type mentioned at the outset, which is characterized by sufficient mechanical stability to withstand damage during the production process and its attachment in or on the product to be labeled, and also also is adequately protected so that it cannot be easily destroyed when the product is used as intended.
  • the invention aims to make such a code carrier as inexpensive as possible with regard to its use in mass products and with simple and reliable devices to be able to read. It is essential that for the purposes of using bulk products both a correspondingly simple design of the code carrier and a simple and reliable procedure for reading out the code are provided. Essentials
  • the code carrier according to the invention essentially consists in that for the evaluation of a stray field which changes in an axis of a plane parallel to the main axis of the code carrier, the code carrier has cutouts, recesses or a changing cross section.
  • a correspondingly stable and inexpensive code carrier can be used, which is distinguished by a relatively simple geometric configuration and nevertheless certainly also in the proposed method for reading out the information of the code carrier or the code can be recognized if the reader is not guided exactly.
  • a stray field to identify the code contained in the code carrier is to a much lesser extent sensitive to distance and allows the use of simple field sensors for the identification of the code.
  • Such a simple code carrier can moreover be integrated in a particularly simple manner in mass articles, such as skis, tennis rackets or the like, during the production process, with a high degree of stability also taking into account the required material selection Production process is ensured.
  • the ability to evaluate such a code carrier by measuring a stray field makes it possible to dispense with complex adjustment and tuning work, as would be required, for example, when measuring magnetic resistances or a coupling field by resonance tuning.
  • the code carrier is in the form of a plate or film, as a result of which the installation in products is particularly simplified, particularly when products with a multilayer structure are involved.
  • the code carrier can also be formed from a conductive metal-plastic emulsion applied to a substrate, such a code carrier being able to be attached to the mass article in a particularly cost-effective manner during production, for example.
  • the code carrier can have openings, recesses or changing cross-section in a particularly simple manner in at least two planes parallel to the main axis, the openings, recesses or the changing cross-section being (are) regularly formed in one plane.
  • Regular training in one level offers the advantages of one
  • the design is advantageously such that the code carrier is arranged invisibly from the outside, the code carrier advantageously being an integral part of the product or being formed by components of the product.
  • the method according to the invention for evaluating the information arranged under a cover layer of a product Code carrier in which the code carrier consists of magnetic, magnetizable and / or electrically conductive material and has a geometric configuration containing the code, is essentially characterized in that an electromagnetic field is generated and that this is essentially parallel to a main axis of the code carrier changing stray field is measured and evaluated. Either a high-frequency alternating field can be used to generate such an electromagnetic field
  • the method according to the invention is thus advantageously characterized in that the
  • code carrier is exposed to a high-frequency alternating field and the changes in the high-frequency field caused by the eddy currents generated in the code carrier are detected via the properties of the high-frequency resonant circuit.
  • a weich ⁇ magnetic material is used as a code carrier and exposed to this soft magnetic material is a magnetic field and measuring the resultant location-dependent magnetic stray field using £ "J magnet-sensitive sensors to advantage.
  • the magnetic field can hiebei both the field of a permanent magnet or a magnetic A constant DC field and, as in a preferred embodiment of the method according to the invention, a periodic alternating magnetic field are generated
  • an at least partially permanent magnetic code carrier can naturally also provide a location-dependent, magnetic stray field which can be measured with magnetically sensitive sensors.
  • a permanently magnetic code carrier is, however, characterized by significantly lower security, since the magnetic stray field is one
  • Such permanent magnets can be changed by a correspondingly high external magnetic field, which means that there is a risk that the code originally introduced will be lost or changed.
  • the method according to the invention is carried out in such a way that the changing stray field of the code carrier in the electromagnetic field is measured with at least two mutually independent sensors and that the measured signals are fed to a common evaluation circuit. In this way, the security of the evaluation of the reading process is significantly improved.
  • the invention further relates to the use of a code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as e.g. Recesses, breakthroughs and / or cross-section changing over an axis of the code carrier, for evaluating the stray field formed in an electromagnetic field for identifying the product by the code carrier arranged under a cover layer of the product, such a code carrier being used, for example, in a sports device, in particular a ski, ball game racket or the like, can be used.
  • a code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as e.g. Recesses, breakthroughs and / or cross-section changing over an axis of the code carrier, for evaluating the stray field formed in an electromagnetic field for identifying the product by the code carrier arranged under a cover layer of the product, such a code carrier being used, for example, in a sports device, in particular a ski, ball game
  • the coding according to the invention also includes a coding system for labeling products
  • At least one code carrier made of magnetic, magnetizable and / or electrically conductive material with a defined shape, such as Recesses, openings and / or over an axis of the
  • Cross section changing code carrier b) at least one field source, and C ) at least one field sensor for measuring the stray field caused by the code carrier created their elements are particularly simple to implement and can be put into practice and, in combination, ensure a high degree of operational safety, robustness and mechanical stability.
  • a coding system can advantageously contain a plate or film as the code carrier, in the context of this coding system the code carrier in a particularly simple manner from a conductive metal-plastic emulsion or magnetic powder-plastic applied to a substrate. Emulsion can be formed, which can further simplify the introduction or application of the code.
  • the code carrier can namely be applied by a simple printing process or by spraying on using a stencil, which leads to a further cost reduction, in particular in the case of bulk articles.
  • the coding system according to the invention is advantageously further developed such that the code carrier has openings, recesses or changing cross-section in at least two planes parallel to the main axis and that the openings, recesses or the changing cross-section is (are) regularly formed in one plane ), which creates a clock trace for the evaluation, which enables the stray field to be measured independently of the speed at which the field source or the field sensor is moved relative to the code carrier.
  • the field source should preferably generate an electromagnetic field that can be displaced relative to the code carrier, wherein a periodic alternating magnetic field can advantageously be used as part of the coding system in the manner already described above with regard to the reading method.
  • the field sensor can be formed by a Hall probe or field plates, with the advantage, in addition, of increasing the accuracy. speed at least one pick-up coil can be provided. However, a pick-up coil can also be used as a field sensor under certain conditions.
  • the coding system is advantageously developed in such a way that a reading device for the code of the code carrier, comprising the field source and the field sensor, an oscillator for an electromagnetic HF field for exciting eddy currents in the code carrier, a trigger and comprises an output stage for converting the attenuation of the RF field, which is dependent on the geometric shape of the code carrier, into an evaluable code signal, with such a configuration of the coding system being particularly easy to evaluate the code by exciting eddy currents in the code carrier.
  • the training for evaluation can also be such that a reading device for the code of the code carrier, comprising the field source and the field sensor, an oscillator for an electromagnetic HF field for exciting eddy currents in the code carrier, a detector coil system, a differential amplifier, a comparator and an output stage for converting the attenuation of the RF field, which is dependent on the geometric shape of the code carrier, into an evaluable code signal.
  • a reading device for the code of the code carrier comprising the field source and the field sensor, an oscillator for an electromagnetic HF field for exciting eddy currents in the code carrier, a detector coil system, a differential amplifier, a comparator and an output stage for converting the attenuation of the RF field, which is dependent on the geometric shape of the code carrier, into an evaluable code signal.
  • FIG. 1 to 6 show schematic views of different code carriers; 7 and 8 schematically the reading of two code carriers and FIG. 9 a basic circuit diagram of an eddy current head; 10 to 20 different reading processes, some with associated signal diagrams; and FIG. 21 shows a block diagram of an embodiment of the evaluation electronics.
  • the code information is in a variation of the cross-section or more generally in a special shape of the code carrier. gers saved.
  • the change in shape determined by a simple coding rule such as, for example, the cross-section, the profile or the surface along at least one spatial axis or in one axis of a plane parallel to the main axis of the code carrier, represents the code it is also advantageous if there is a "clock track" parallel to the "code track” so that the signals can be correctly assigned in any case regardless of the scanning speed.
  • FIGS. 1 to 6 Examples of the shape of the code carrier are shown in FIGS. 1 to 6.
  • the code carrier can either consist of an electrically conductive metal or of a soft magnetic or else of a hard magnetic material.
  • the code that is stored in the change in shape is always detected by a spatial distortion of the electromagnetic field or stray field caused thereby.
  • the presence of the projections 3 is determined by the significantly stronger damping of the eddy currents, in the second or third case the projections can be detected with field sensors using their stray fields.
  • the code carrier is a body 4, the surface of which has ribs 5 in an arrangement that means the code.
  • the code carrier can again consist of an electrically conductive metal as well as a soft magnetic or also hard magnetic material.
  • 3 shows in cross section a metal plate 6 which has bulges 7 for coding at certain intervals.
  • an electrically conductive metal appears to be suitable as the code carrier material.
  • An eddy current method is therefore suitable for reading if the bulges 7 lie inside, flat parts of the plate 6, however, outside the detectable area of an eddy current sensor (not shown in more detail).
  • a further advantageous embodiment for such code carriers can e.g. formed by a metal foil 8, as shown in FIG. This consists of a good leader.
  • the coding results from the arrangement of holes or recesses 9 and 9 '.
  • the holes are circular in Fig. 4, but can also have any other shape.
  • the optimal shape of the holes should be adapted to the shape and type of sensor that is to be used for reading the code information. The presence of the holes is detected, for example, with a commercially available eddy current sensor. It should be pointed out that the size of the holes and thus the achievable density of the bits / area unit determines the distance from which the code must be read. The greater this distance, the larger the diameter of these holes must be.
  • Such a metal foil with punched holes is a particularly inexpensive and easily accommodatable code carrier.
  • the continuous row of holes 9 'adjacent to the edge represents the cycle track which is used for synchronization, while the information is contained in the further rows 9 of holes.
  • Fig. 5 shows another form of a code carrier similar to that of Fig.l.
  • the plate 10 is provided on both sides with projections 11 and thus coded.
  • one side can be used as a "code track” and the other as a "clock track”.
  • the code carrier can again consist of an electrically conductive metal as well as a soft magnetic or also hard magnetic material.
  • the code carrier consists of disks 12 arranged one behind the other. Each disc carries extensions 13 along its circumference, the arrangement of which represents the code.
  • An analogous function can also be achieved by appropriately shaping a cylindrical rod.
  • the code carrier can again consist of both an electrically conductive metal and a soft magnetic or also hard magnetic material.
  • code carrier can be easily integrated into the workpiece and not visible from the outside or at least protected under a cover layer.
  • the code is determined once at the start of production, for example by mechanical processing of the code carrier, and cannot and should not be changed.
  • the code is only destroyed by destroying the element. In any case, there is visible damage to the product, so that the change in the code carrier is also visible. Unwanted manipulations, or those with fraudulent intentions, can thus easily be discovered.
  • the information on the code carrier is always read without contact.
  • the code carrier is located inside the product and is not located right on the surface.
  • the materials used in the product can limit the reading methods that can be used. Reading methods are therefore also possible and described below which, for example, also allow a code to be detected on the code carrier in the presence of metals or through metals.
  • the code of the code carrier can be detected in various ways.
  • the reading method to be used depends, among other things, on the material of the code carrier and its environment, i.e. on the materials used in the product.
  • An electrically conductive code carrier e.g. made of copper, can be scanned via a stray field caused by eddy currents. If the code carrier consists of a soft magnetic material, such as iron or permalloy, the shape variation and thus the code can be scanned using its magnetic stray field. If the code carrier consists of a soft magnetic, metallic material, magnet-inductive and eddy current methods can be combined, which increases reading security.
  • the magnetic methods generally have the advantage that the code can also be detected in the presence of other metals.
  • stray fields can basically have the following physical causes: stray fields can be caused by eddy currents or magnetically. In both cases, the reading process is carried out by scanning the stray field.
  • eddy currents are generated in a metallic conductor by a high-frequency alternating field.
  • the metallic conductor is the code carrier here.
  • the eddy currents generated therein dampen the HF oscillator. This damping can be measured either with a reduction in the amplitude of the oscillator or as with commercially available sensors which both generate the HF field and measure the damping Shift of the resonance frequency of the oscillator can be determined.
  • the shape-dependent stray field of the soft or hard magnetic code carrier is registered with conventional field measuring probes. It is clear that the methods are related to the Maxwell equations, but there are fundamental differences in the physical mechanisms. These reading methods are described in more detail below.
  • Any metal is suitable as a code carrier when scanning stray fields caused by eddy currents. It is preferably a good electrical conductor. However, studies have shown that the size of the electrical conductivity only slightly influences the distance dependence of the commercially available sensors. Similarly, the (soft) magnetic state of a metallic code carrier hardly influences the threshold value of the distance at which the commercial eddy current sensor changes its output level suddenly. Commercial eddy current sensors can, however, be sensitive in their sensitivity, i.e. in their dependency on distance can be significantly improved. The arrangement of these detector coils must be adapted to the shape of the emission lobe of the transmitter.
  • FIG. 7 schematically shows a reading arrangement for stray fields caused by eddy currents. Either the reading head 14 is moved past the code carrier 16 in the direction of the arrow 15, or the code carrier 16 is moved past the fixed reading head 14. One or more small detector coils can additionally be accommodated directly at the end of the emitting oscillator head 14 in order to improve the sensitivity. The one with a conveyor belt normal speeds do not interfere with the reading process.
  • 7b is a top view of the measuring arrangement according to FIG. 7a.
  • the reference number 17 denotes holes in the code carrier 16, the arrangement of which represents the code.
  • FIG. 8 shows an arrangement similar to that of FIG. 7, the code carrier consisting of a metal plate with lateral extensions, as shown in FIG. It should be noted that the distance x of the plate from the sensor required for code detection and the height h of these lateral extensions must be such that the detectability limit, which is indicated by the dashed line s in FIG. 8, of the sensor is greater than x but smaller as x + h i ⁇ t. As already mentioned, s can be increased by using additional detector coils to increase the sensitivity, but then the distance between adjacent "bits", i.e. the lateral extensions must also be enlarged.
  • Fig .9 shows schematically the basic apparatus for a reader for stray fields caused by eddy currents.
  • the principle of the scanning is based on contactless, electronically operating proximity sensors.
  • the reader essentially consists of an oscillator 18, a trigger 19, and an amplifying logic switching output 20.
  • the distance of the sensor from the code carrier is essentially determined by the diameter of the emitting sensor surface.
  • a differential amplifier can also be used, for example, which amplifies the signal generated by the above-mentioned additional detector coils 48. This signal arrives at a comparator, which compares it with an adjustable reference signal and, depending on this, emits a signal ("bit") or not. The evaluation is then carried out again in a corresponding logic circuit (20).
  • the oscillator 18 uses an oscillating circuit coil to generate an electromagnetic RF field 21 which emerges from the active surface of the sensor. The frequency of this alternating field determines the depth of penetration into a metallic body, as represented here by the code carrier 22.
  • eddy currents indicated schematically by 43 are generated by the alternating electromagnetic field according to the Maxwell equations, which are directed in such a way that the primary field is shielded.
  • the strength of these eddy currents depends on the frequency of the alternating field, on the electrical conductivity and, in the case of a magnetic material, also on its permeability.
  • the sensitivity of the overall system can in principle be influenced by a suitable choice of the material of the code carrier.
  • tests show that commercially available eddy current sensors are generally too insensitive to be used in a material-specific manner.
  • the formation of these eddy currents draws energy from the oscillator. This causes a change in amplitude or a change in the resonance frequency at the output of the oscillator, which is converted into a logic signal via the trigger 19 and the output stage 20.
  • the system advantageously consists of at least two coils, which are wound or arranged in such a way that the induction signal generated in them is antiparallel, i.e. cancel each other out. If a metallic code carrier is brought close to the oscillator, it changes the strength and direction of the vortex field. This changes the symmetry of the detector coil system and results in a signal caused by the code carrier. In this way, the sensitivity with which, for example, a hole is determined in a metallic foil can be significantly increased.
  • the strength of these eddy currents and thus the strength of this damping depends essentially on the distance of the sensor metal. If the sensitivity limit s is such that parts of a geometric shape which represents the code exceed or fall below this limit, the parts scanned in this way can be implemented as a code (see, for example, FIG. 8). In this way, for example, ribs or ridges can be detected on a metallic code carrier (for example, Fig. 2, Fig. 3, Fig. 5 or Fig. 6). Even three-dimensional cross-sectional changes on a metallic code carrier can thus be detected as a code with an eddy current sensor if the sensitivity limit passes through this cross-sectional variation.
  • Another possibility is that the presence or absence of a metal is detected if it is within the sensitivity limit.
  • holes can be detected in a metallic foil, for example, if the hole diameter corresponds approximately to the sensor diameter.
  • additional detector coils however, holes with smaller diameters can also be detected, as a result of which the overall information density can be increased.
  • very thin, metallic foils can be used, which is particularly advantageous in terms of production technology. It is also possible to implement the code by means of electrically conductive lacquers or metal powder which are suspended in plastics, and then to detect it by means of eddy currents.
  • Eddy currents can only be used to read the code if there are no other metals in the product in the immediate vicinity of the code carrier. If this is the case, the code carrier must be within the sensitivity limit s and all other metallic components are located outside the sensitivity limit s. In this case, however, magnetically detectable code carriers appear to be particularly advantageous. This means that the code of both soft-magnetic and hard-magnetic code carriers can be detected through other metallic materials, for example made of aluminum, copper, etc.
  • the code can be detected to the outside by the geometry-dependent stray field of the code carrier.
  • the code carrier is magnetized by an exciting magnetic field generated from outside. This magnetic field can be either a direct field or an alternating field.
  • FIG. 10 shows a reading arrangement for magnetically caused stray fields with magnetization with a constant field, FIG. 11 showing a signal obtained in this way.
  • the constant field is generated, for example, by a permanent magnet 23.
  • a field coil through which direct current flows can also be used.
  • the permanent magnet or the field coil should be designed so that the magnetic field generated by it is homogeneous over the length of the code carrier. It is particularly advantageous, it appears when the thickness of the Magnetfelde ⁇ H is chosen so that the code carrier, the highest value of the permeability ⁇ m ax of the material used is achieved. A significant improvement in the sensitivity of the system can thereby be achieved.
  • the product and with it the code carrier 24 is moved in the direction of arrow 25 by the magnetic field.
  • the field lines of the external magnetic field are distorted in a manner that is significant for the special shape of the code carrier.
  • An example of a field line distribution is shown schematically in Fig.12.
  • the shape-specific field line distribution over the length of the code carrier is measured, for example, via Hall probes 26.
  • other corresponding sensors for example field plates, magnetoresistive sensors, etc., can also be used.
  • the voltage which is induced in additional pick-up coils can also be used here (for example FIG. 13) when the code carrier is moved through a pick-up coil and in this way a magnetic flux change and thereby generating a signal.
  • a field coil is designated 27 in FIG.
  • the code carrier 28 is moved in the field coil and the magnetic field lines shown are formed, which can be used to read the code.
  • Conventional, correspondingly sensitive field sensors are particularly suitable here, although the size of the sensor (active area) must correspond approximately to the spatial extent of the recess, elevation or change in cross-section representing a bit.
  • a so-called pick-up coil is suitable for reading the code.
  • the field coil should be designed so that the magnetic field generated by it st homogeneously over the length of the code carrier. It appears to be particularly advantageous if the strength of the magnetic field H is selected so that the highest value of the permeability ⁇ m a of the material used for the code carrier is reached.
  • the frequency of the alternating field should be relatively low (ie f ⁇ 10 kHz) in order to avoid shielding effects via eddy currents. A skilful choice of the modulation field and its frequency can significantly improve the sensitivity of the system.
  • FIG. 13 shows an arrangement suitable for this and FIG. 14 schematically shows the resulting read signal.
  • the code carrier 30 is moved in the direction of the arrow 31.
  • the pick-up spool (s) 32 creates a voltage, the amplitude of which is proportional to the field line density and thus to the special shape of the code carrier.
  • “Compensated" pick-up system characterized by the fact that there is no signal in the absence of a code carrier, ie the voltage is only proportional to the magnetization.
  • adjacent bits can be identified with high security in a location-resolving manner without using a "track".
  • Particular attention must be paid to the spatial resolution of the pick-up system. The greater the average distance between code carrier and pick-up coils, the worse the spatial resolution in general. A high spatial resolution can then be achieved by a special shaping of the pick-up coils.
  • a pick-up system has a high spatial resolution if the magnetic field generated by this "fictitious" at the location of the "bit” goes large and outside towards zero.
  • Another arrangement would be the use of a dipole-compensated coaxial system which has a higher spatial resolution.
  • the location resolution can be further improved by the arrangement of additional coils.
  • the length of a pick-up coil is in turn determined to a maximum by the spatial extent of a change in cross-section representing a bit - a shorter system definitely offers more spatial resolution, but less sensitivity.
  • the use of a periodic alternating field is advantageous in terms of measurement technology, since the use of frequency- and phase-sensitive amplifiers enables a significant improvement in the signal-to-noise ratio of the code signal to be obtained.
  • the amplitude of the code signal changes in the rhythm of the shape variation of the code carrier, so that the read signal reproduces the code of the code carrier.
  • the use of an integrator in signal processing is particularly advantageous, as a result of which the signal voltage is independent of the frequency de Erregerfelde ⁇ but also from a movement of the object.
  • the integrator With the integration required here, the integrator must have two negative feedbacks with two different time constants ti and t 2 .
  • the time constant ti must be less than the period T in order to integrate the 'periodic AC voltage.
  • the time constant t 2 must be large in relation to ti - it should compensate for the integration of offset voltage or other long-term interference voltages which is very disruptive for integrators.
  • An example of a usable integrator is a hysteresis.
  • the output signal is in turn proportional to the magnetization and thus to the cross section representing the code.
  • a Hall probe can also be used here, for example, which measures the stray field which varies in shape.
  • the simultaneous use of a pick-up system with a sensor for measuring the stray field is particularly advantageous.
  • the corresponding measuring electronics are connected to both measuring systems. Only when the two independent systems recognize a "bit" is it actually registered as belonging to the code. In this way, the security of the system against interferences increases significantly.
  • a soft magnetic yoke 33 which has one or more measuring and excitation coils, is used.
  • the code carrier can consist of a soft magnetic or a permanent magnetic material which is provided with ribs. The sequence of the ribs represents the code. The ribs are labeled 34 and 35.
  • the code carrier is partially magnetized by the magnetic yoke 33 moving past if the code carrier is soft magnetic. In the case of a permanent magnetic code carrier, this code carrier magnetizes the soft magnetic yoke in the opposite way. In both cases the change in flow is measured by at least one secondary coil on the same yoke without contact.
  • the excitation coil can be supplied with direct and / or alternating current.
  • the strength of the current is determined here by the material of the yoke.
  • the current should in turn be set so that the total permeability of the circuit becomes maximum.
  • Other sensors sensitive to magnetic fields can also be used here, such as Hall probes and field measuring plates. These are located in the air gap between the code carrier, which is built into the product, and the soft magnetic yoke.
  • the read code results from the measurement of the spatially resolved scanned magnetic field or stray field which varies in this air gap and which is a result of the variation in the magnetic resistance caused by the ribs.
  • the result is an output signal whose amplitude represents a bit sequence that corresponds to the code.
  • Two soft magnetic code carriers can also be accommodated and read simultaneously on the front and on the back of the product (which doubles the bit density to be accommodated). If the distance d between the code carriers is greater than the distance y between the code carrier and the soft magnetic yoke, there is no influence (see FIG. 17).
  • the use of a combined measuring system appears to be particularly advantageous consisting of measuring coils 44 on the legs of the soft magnetic yoke 33 and the additional use of field sensors, for example Hall sensors 26. Only when both systems indicate the presence of a bit is a code actually registered. This again significantly increases the security of the system against undesired interference voltages.
  • the primary coil is designated 45 and is operated simultaneously with direct and alternating current.
  • the secondary coils 44 are wound anti-parallel.
  • a strip of a hard magnetic film 46 is first fully magnetized in an axis 47. Then it is machined according to the code by punching on its edges (see FIG. 19). The code is registered by measuring the stray field at the edges (demagnetizing field), the use of correspondingly small Hall probes here appearing to be particularly advantageous.
  • a strip made of a hard magnetic film is partially magnetized in different directions with the stray field of the air gap of a soft magnetic yoke prior to installation in the product (see FIG. 20).
  • the width of the magnetized area is determined here by the air gap.
  • the stray field of these magnetized areas can now be registered from the outside with field sensors (Hall probe, pick-up system, Fe yoke). Since the code for the products to be registered here has to be ascertained and read at greater intervals, correspondingly large areas must also be magnetized on the code carrier.
  • the width of the magnetized Areas correspond approximately to the distance at which the code can still be read.
  • the clock information is computed arithmetically from the width of a bit (NS stripe).
  • FIG. 21 A purely schematic block diagram of evaluation electronics of the measured signals is shown in FIG. 21.
  • the controller 36 RF transmitter, excitation current, Hall current
  • the signals coming from the sensors are amplified in the amplifier 38 (signal processing) and converted into digital signals in an analog-digital converter 39 and forwarded to the computer 40 (code recognition, evaluation, data storage).
  • code recognition, evaluation, data storage In the case of registration of the code with the aid of pick-up coils, it is better to use a hysteresis scanner to register the signal, as already mentioned, the simultaneous use of several measuring systems (for example pick-up coils and field sensors) appears. particularly cheap. Only when several measuring methods report a bit is it actually forwarded to the computer as read.
  • the code is recognized, evaluated and data stored in the computer, and the feed control 41 regulates the activation of the sensors 36, if necessary with the position detection 42 being interposed.
  • the invention serves for the identification (coding) of products which are manufactured in large numbers. This method is mainly intended for monitoring the production process, but also for safety, quality and guarantee services.
  • a feature is the accommodation of a code on a code carrier, which can consist of an electrically conductive material (metal), but also of a magnetic (soft or permanent magnetic) or magnetizable material. The choice of the material is decisive for the reading method or methods, but also for the legibility of the code.
  • the code consists of a variation in shape, changes in cross-section, changes in the contours, ribs or recesses or holes in the code carrier, or else a pattern made by means of a corresponding metal-plastic emulsion, for example "conductive lacquer", which is above it Eddy currents caused by stray field or also by their geometrically determined magnetic stray field can be detected.
  • the correspondingly determined, location-dependent analog measurement signal which becomes redundant through the simultaneous use of several independent reading methods, can be converted into digital information that corresponds to the code.
  • the code element should preferably be mechanically and thermally robust and invisible or covered from the outside and is therefore largely insensitive to environmental influences and preferably to be accommodated in or on the product and possibly inseparably connected to it.
  • the code carrier can have any shape.
  • the outer shape can be adapted to the shape of the product.
  • the invention is also distinguished by the high degree of flexibility in terms of shape.
  • parts of the product which are made of electrically conductive or magnetic material can also be used as code carriers by changing the cross-section, the outline, the surface or by making recesses of any shape.
  • the code carrier can consist of permanent magnetic elements, preferably a hard magnetic foil, plastic-magnetic powder emulsion or metal-plastic emulsion. It is advantageous that a magnetic code carrier can be detected even when other conductive components of the workpiece are present. This also applies if they are arranged directly above or below the code carrier.
  • eddy currents are generated by a high-frequency alternating field. Whether or not eddy currents actually arise depends to a large extent on the distance between the vortex flow head and the metallic code carrier.
  • the code is now realized in the code carrier by means of a special shaping (cross section, thickness, holes, etc.). As a result, the distance between the eddy current head and the code carrier is varied such that a logical "O" (distance too large) or a "1" (distance sufficiently small) is created.
  • the properties of the high-frequency resonant circuit which are changed as a result of the eddy currents thus generated are thus used as a signal for determining the code.
  • the code is generated in a soft magnetic material by means of a special shape (cross section, surface, etc.).
  • the location-dependent stray field which represents the code, is scanned with the aid of field-sensitive sensors.
  • the location-dependent stray field that represents the code can be registered by moving the product with the code carrier through a coil system with the aid of the pick-up voltage thus created.
  • the magnetizing magnetic field can be a periodic alternating field.
  • the location-dependent stray field, which represents the code, is detected with the aid of a location-resolving pick-up coil system as a periodic AC voltage.
  • the use of frequency- and phase-sensitive amplifiers for signal processing, which result in a better signal / interference ratio, is advantageous. Another possibility is the integration of the signal, as a result of which the frequency of the exciting field no longer influences the size of the measurement signal.
  • the location-dependent stray field which represents the code, can also be detected as a periodic alternating voltage using magnetically sensitive sensors, such as Hall sensors or field plates.
  • the periodic AC voltage makes the use of a frequency and phase sensitive amplifier for signal processing particularly advantageous. The result is a better signal / interference ratio.
  • the code contained in a soft magnetic code carrier which is fixed by special shaping, can be fixed by means of a soft magnetic yoke.
  • the code will be determined by changing the magnetic resistance either by monitoring the power consumption of the primary coil or also with the aid of additional special secondary coils or again by means of field-sensitive sensors, the latter responding to the change in the stray field in the air gap.
  • the stray fields that vary in this way can be carried out with the aid of a soft magnetic yoke (on which induction coils are located) or with correspondingly small ones Field sensors (Hall probes etc.) are scanned.
  • the arrangement of the detector reading heads is preferably such that reading is carried out without contact.
  • the size of the reading heads generally corresponds approximately to the spatial extent of the feature describing a bit, such as a change in cross-section. Otherwise, the arrangement of the heads can be adapted to the geometry of the code carrier and that of the product, and is therefore freely selectable.
  • the distance is determined by the geometric shape of a "bit" and its size, but also by the underlying physical laws, for example the distance dependence of the stray field.
  • the optimal shape of the recesses or changes in cross-section representing the "bits" is directly related to the shape of the active surface of the sensor used.
  • the code of the code carrier can be determined by means of a relative movement between the code carrier and the corresponding sensor, essentially along the main axis containing the code, with either the speed being known or a "clock track" being used for a corresponding resolution of the code.
  • the entire code carrier can also be scanned in one step, so that with a number of sensors corresponding to the information density, a relative movement between the code carrier and sensor (s) can be dispensed with and the time for reading the code can be shortened .

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

Dans un support de code (1) pour l'analyse d'un code servant à identifier des produits, support disposé sous une couche de protection du produit à identifier et constitué d'un matériau magnétique, magnétisable et/ou électriquement conducteur, ce support de code présente, pour l'analyse d'un champ de fuite variant dans un axe (2) d'un plan parallèle à l'axe principal du support de code, des découpures, des évidements ou une section (3) variable.
EP19910903419 1990-01-23 1991-01-23 Procede et dispositif pour l'analyse des informations d'un support de code Withdrawn EP0464186A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT148/90 1990-01-23
AT14890A AT398497B (de) 1990-01-23 1990-01-23 Codiersystem und codeträger

Publications (1)

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EP0464186A1 true EP0464186A1 (fr) 1992-01-08

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EP19910903419 Withdrawn EP0464186A1 (fr) 1990-01-23 1991-01-23 Procede et dispositif pour l'analyse des informations d'un support de code

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EP (1) EP0464186A1 (fr)
JP (1) JPH04504479A (fr)
AT (1) AT398497B (fr)
CA (1) CA2049934A1 (fr)
WO (1) WO1991011777A1 (fr)

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GB9922517D0 (en) * 1999-09-24 1999-11-24 Thorn Secure Science Ltd A device for reading an elongate magnetic data carrier
DE102005008967A1 (de) * 2005-02-28 2006-08-31 Giesecke & Devrient Gmbh Verfahren und Vorrichtung zum Messen magnetischer Eigenschaften von Dokumenten
US7355150B2 (en) * 2006-03-23 2008-04-08 Access Business Group International Llc Food preparation system with inductive power
FI20085456A7 (fi) 2008-05-15 2009-11-16 Valtion Teknillinen Tutkimuskeskus Menetelmä ja laitteisto sähköisen koodin tunnistamiseksi
IES20110196A2 (en) * 2010-04-20 2011-11-09 Limerick Inst Of Technology Improvements in and relating to a sheet orientation detection system
DE102022124639A1 (de) 2022-09-26 2024-03-28 Audi Aktiengesellschaft Vorrichtung und Verfahren zur Werkstückträgeridentifikation

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DE2336246A1 (de) * 1973-07-17 1975-02-06 Interroll Foerdertechnik Gmbh Einstellbarer codierreflektor
US4134538A (en) * 1976-03-18 1979-01-16 La Societe Metalimphy Process and apparatus for identification of objects
AU533081B2 (en) * 1979-03-02 1983-10-27 Chubb Security Australia Pty Limited Code identification apparatus
FR2508203A1 (fr) * 1981-06-19 1982-12-24 Cii Honeywell Bull Dispositif de transduction magnetoresistant de lecture d'informations codees a faible densite
DE3331694A1 (de) * 1983-09-02 1985-03-21 Robert Bosch Gmbh, 7000 Stuttgart Kodiersystem zum erfassen von daten von werkstuecken auf transferstrassen
DE3729740A1 (de) * 1987-09-04 1989-03-23 Horstmann Electronic Identifikationssystem fuer bewegbare module
DE3901950A1 (de) * 1989-01-24 1990-08-02 Mel Mikroelektronik Gmbh Induktives erkennungssystem

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Title
See references of WO9111777A1 *

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ATA14890A (de) 1994-04-15
AT398497B (de) 1994-12-27
JPH04504479A (ja) 1992-08-06
CA2049934A1 (fr) 1991-07-24
WO1991011777A1 (fr) 1991-08-08

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