JP2011081012A - Measuring probe and device for proving the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring probe for measuring magnetization data of at least one item such as a security document having one magnetic security material, and to provide a proving device having the measuring probe. <P>SOLUTION: The measuring probe includes at least one core-less magnetization coil 3, and at least two magnetic field sensors 4s and 4c are arranged in it at both ends of the magnetization coil 3. The proving device determines a magnetic security printed matter using the measuring probe. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention records and compares the magnetic characteristics of a document or article and the magnetic characteristics are contained within the document or article or tied to a magnetic material applied to the document or article by ink, coating composition or foil. The present invention relates to a measurement probe for certifying a security document or an article and a proof device having the same.

Magnetic inks are known in the technical field of security printing. “US banknote black”, which has been printed on dollar bills for more than a century, is based on magnetite powder Fe ₃ O ₄ used as a black pigment. Iron, cobalt and nickel powder, brown iron oxide Fe ₂ O ₃ , chromium dioxide CrO ₂ , ferrite MFe ₂ O ₃ (where M is Mg ²⁺ , Mn ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ Divalent iron such as ZnFe ₂ O ₃ , garnet A ₃ B ₅ O ₁₂ (where A is trivalent rare earth iron, B is Al ³⁺ , Fe ³⁺ , Ga ³⁺ , Bi ^3+, etc.) ), Many other magnetic materials such as yttrium / iron / garnet Y ₃ Fe ₅ O ₁₂ (YIG) and others have been proposed and used as pigments in ink and coating compositions.

  A magnetic material is markedly characterized by the dependence of its magnetization intensity B on the function of the applied external magnetic field H. In the low magnetic field H, the magnetization B is roughly proportional to H, ie B = μ · H; the proportionality constant μ is called the relative permeability. The non-linear behavior of the magnetization function B (H) is almost observed in the high magnetic field H, where μ is finally at magnetic saturation, which is substantially equal to 1. All magnetic materials exhibit magnetic saturation.

  Many magnetic materials also exhibit a non-reciprocal magnetization function, ie, B remains at a certain value Br (magnetic remanence) as the magnetic field strength H decreases from saturation to zero. In order to return B to zero again, a negative magnetic field -Hc (magnetic coercivity) must be applied to the material. This non-reciprocal magnetic behavior is called hysteresis and the B (H) curve or magnetization feature of such a material is called the hysteresis curve.

FIG. 1 a shows the hysteresis curve of the retentive magnetic material, where the magnetization strength B is plotted against the magnetic field strength H. The non-linear characteristics of the B (H) magnetization function are shown along with the coercivity Hc of the magnetic material, the residual magnetization Br after removal of the external field, and the saturation magnetization (μ = 1) Bs of the material. Hc is a material specific and quantity independent intensive value, while Br and Bs are quantity dependent extensive values.

  In practical applications, the magnetization B as a function of H or the time variable dB (H) / dt as a function of magnetic induction or H (t) can be measured using a suitable sensing device. FIG. 1b shows the magnetic induction dB / dt obtained by the sensing coil and corresponding to the path from point b to point d on the hysteresis curve shown in FIG. 1a.

  For the purpose of proofing security documents or articles carrying magnetic inks or coatings, it is important to use the material-related magnetization (eg, hysteresis) curve B (H) = μ · H of magnetic properties. Measurement of the magnetization or hysteresis curve usually requires heavy experimental equipment. Such an installation or hysteresis meter has a measurement probe for the formation and sensing of a magnetic field, together with the necessary drivers and data processing electronics.

The layout of a magnetic measurement probe as known in the art and used in conjunction with a laboratory hysteresis meter is shown schematically in FIG. 2a. A sample of magnetic material M ′ is placed inside the first part of the magnetizing coil 3. The coil 3 is a cylinder-shaped coil without a magnetic core, that is, a solenoid that is driven by a periodically changing current I (t) and thereby generates a periodically changing magnetic field H (t). The magnetic material M ′ inside the coil is magnetized by the field H (t) and causes an additional element B (t) = A · μ (H) · H (t) in the magnetic field H (t). A is a proportionality constant related to the amount of magnetic material present.

感知及び補償コイルは機械的に対称的な方法で配置され、互いに関して電気的に平衡にされ、これら両方は、感知コイルの内部に磁性材料が存在しない場合にＵｓ−Ｕｃがゼロになるように、共通の接地（Ｇｎｄ）に接続される。感知コイル４ｓの内部に磁性材料が存在する場合は、非対称的な寄与Ａ・μ（Ｈ）＝ｄＢ_M／ｄｔが生じ、これはＵｓ−Ｕｃの差として検出できる。 The sensing coil 4s is placed on top of the first part of the magnetizing coil and houses the sample M ′. The compensation coil 4c is placed on top of the second part of the magnetizing coil and does not contain a sample. The changing magnetic field H (t) generates voltages Us, Uc in the sensing and compensation coils, respectively:

The sensing and compensation coils are arranged in a mechanically symmetric manner and are electrically balanced with respect to each other such that Us− Uc is zero when there is no magnetic material inside the sensing coil. , Connected to a common ground (Gnd). When a magnetic material is present inside the sensing coil 4s, an asymmetric contribution A · μ (H) = dB _M / dt is generated, which can be detected as a difference of Us−Uc.

  In order to perform this measurement, the magnetic sample material must be placed inside the magnetizing coil to ensure uniform magnetic field conditions across the entire sample volume. Such a state is prominently present inside the cylinder coil. In this case, the magnetic field lines are parallel and have a constant density. Outside the coil, the magnetic field lines diffuse and the field becomes inhomogeneous. Therefore, the measurement of the magnetization characteristics of the bulk material usually does not occur outside the magnetizing coil. The reason is that all parts of the sample under test do not receive the same field strength. To remedy this drawback, some instruments use a similar pair of large coils having their axes aligned. While such coils, known as Helmholtz coils, can produce a volume of homogeneous magnetic field in free space, they require the insertion of a sample between both coil parts.

  Due to the geometric constraints described above, spread flat magnetic objects such as magnetic prints or magnetically coated articles are difficult to handle as samples. These must be cut into pieces so that they fit into the available measurement space of the hysteresis meter (destructive analysis method) or very special instruments with coils at the top and bottom of the sample to be measured must be provided I must.

  Nondestructive M (H) magnetic measurement probes are disclosed in, for example, US Pat. No. 4,843,316, US Pat. No. 4,901,016, JP02,248,879, FR-A- No. 2,686,980 and DE-A-313887. However, none of these probes are suitable for “on top” proof of spread sheets such as magnetic prints or paper carrying coatings. Conventional measurement probes have been considered for characterizing recording media having a particularly flat surface; this probe cannot be successfully applied to structured surfaces such as those represented by magnetic intaglio.

U.S. Pat. No. 4,843,316 US Pat. No. 4,901,016 JP02,248,879 specification FR-A-2,686980 specification DE-A-313887 Specification

  It would be desirable to have a means available for non-destructive evaluation of the magnetic characteristics of sheet-like spread tissue material such as paper carrying magnetic prints or coatings. Further, there is provided a method and apparatus that can be used to enable “on top” proof of magnetic features on a printed valuable document or article without the need for two matched magnetizing coils on both sides of the document. It is particularly desirable to obtain.

  It is an object of the present invention to provide a measurement probe that allows measurement of the magnetic characteristics of a sheet-like material without any restrictions with respect to the spread of the material sheet. Such measurement probes are reliable in sheet-like material, easy to implement, and fast by simply positioning and / or moving the measurement probe over and / or above the surface of a document or article. It is possible to prove prominently.

  This object of the invention is solved by a magnetic measurement probe and a proving device having it and by a proving method carried out using said device according to the features of the claims.

FIG. 1a is a diagram showing a typical magnetization (hysteresis) curve B (H) of a coercive magnetic material showing remanent and saturation magnetization values Br and Bs together with a coercive magnetic field Hc. FIG. 1b is a diagram showing a magnetic induction curve dB (H) / dt corresponding to the path from point b to point c of the hysteresis curve of FIG. 1a. FIG. 2a shows a schematic layout of a standard magnetic measurement probe for acquisition of magnetization or hysteresis data of a magnetic sample M ′ located inside a magnetizing coil. FIG. 2b shows a schematic layout of a novel magnetic measurement probe as used for “on top” acquisition of the magnetization or hysteresis data of a sheet-like magnetic sample M located in front of and outside the magnetizing coil. FIG. FIG. 3a shows a first preferred embodiment of a magnetic measurement probe for measuring magnetic induction data of a sheet-like material 7 by means of an inductive sensing coil 4s and a compensation coil 4c arranged at both ends in the cavity of the magnetizing coil 3. FIG. FIG. 3b shows a second preferred embodiment of a magnetic measuring probe for measuring the magnetization data of a sheet-like material 7 by means of a field sensing element 8s and a compensation element 8c arranged at both ends in the cavity of the magnetizing coil 3. It is a longitudinal cross-sectional view. FIG. 2 is a partial electrical diagram of an embodiment of a proving device that uses a magnetic measurement probe according to the present invention. Three certification devices MD, MD ′, MD according to the present invention that acquire magnetic characteristics of items and upload the obtained data to a security server for remote certification via communication links 1, 1 ′, 1 ″. It is a figure which shows roughly a part of embodiment which has ″.

The present invention will be described with reference to the drawings.
The present invention is based on a significant improvement in magnetic measurement probes that allow for “on top” acquisition of magnetic features such as B (H) hysteresis or dB (H) / dt magnetization features of sheet-like materials. Here, the material can be tissue or flat.

  In fact, surprisingly, the magnetic properties of thin sheet-like materials such as prints or coatings made with coating compositions composed of ink or magnetic security pigments when using special and novel coil or sensor configurations It has been found that can be obtained quickly and reliably outside the bore of the magnetizing coil. A measurement probe according to such a discovery is shown in FIGS. 3a and 3b as two exemplary embodiments.

A cylinder-shaped coreless magnetic solenoid coil 3 made of insulated and electrically conductive wires is used as a magnetizing coil to generate a magnetic field H (t). This magnetic field is homogeneous inside the magnetizing coil 3 (field zone H ₁ ) and inhomogeneous outside the magnetizing coil 3 (field zone H ₂ ). There are also two small field areas H ₃ with substantial field homogeneity outside the magnetizing coil 3 at both ends near the magnetic poles of the coil. In this case, substantial field homogeneity should mean that the magnetic field strength in the H ₃ zone does not deviate from the value H ₁ possessed inside the magnetizing coil 3 by 15%, preferably more than 10%. This should be received as the definition of the H ₃ area.

The present invention relies on the use of such a polar zone H ₃ to examine the magnetic characteristics of a flat and spread item 7, in particular a security document carrying a magnetic security marking M. According to one aspect of the present invention, as shown schematically in the layout according to Figure 2b, 2 or more magnetic sensors, preferably in the vicinity of the pole area H ₃ of magnetizing coil 3 at its both ends It is arranged inside the magnetizing coil 3.

  In the first embodiment of the magnetic measurement probe according to FIG. 3a, the magnetic sensors are an inductive sensing coil 4s and a compensation coil 4c. They are preferably located symmetrically inside the magnetizing coil 3 at both ends and have their magnetic coil axis substantially aligned with the coil axis CC of the magnetizing coil 3. According to the invention, the outer diameter of the sensing and compensation coils 4 s, 4 c must be smaller than the inner diameter of the magnetizing coil 3. Furthermore, the sensing and compensation coils are preferably kept thin; that is, their outer diameter is kept close to their inner diameter. The use of an induction coil makes it possible to perform a dynamic measurement of the magnetization change dB / dt.

  Instead, as shown in the second embodiment of the magnetic measurement probe according to FIG. 3b, the magnetic sensor is a field sensing element 8s and a compensation element 8c, so that the field sensing element 8s and the compensation element 8c are magnetized coils. Must be smaller than the inner diameter. These elements are preferably located symmetrically at both ends within the magnetizing coil 3 and have their magnetic axis substantially aligned with the coil axis CC of the magnetizing coil 3. The field sensing element 8s and the compensation element 8c can be of any type known in the art; in particular, they can be Hall effect sensors or magnetoresistive (MR, GMR) sensors. Both types of small sensors are known in the art and are commercially available. The use of a magnetic field sensor makes it possible to carry out a static measurement of the magnetization B.

For correct operation, the sheet-like item 7 carrying the magnetic material M is preferably held in place with respect to the magnetic measurement probe by the probe holder so that the inductive sensing coil or magnetic field sensor faces the magnetic security material M. To do. The magnetic field lines of the magnetizing coil 3 should penetrate into the sheet-like item 7 substantially perpendicular to its surface. The inductive sensing coil or magnetic field sensor need not touch the magnetic security material M directly. If necessary, the magnetic security material M deviates from its value H ₁ in the coil 3 by 15%, preferably more than 10% if the magnetic field H ₃ in the relevant measurement region still satisfies the homogeneous state described above. If not, it can be located at a distance of up to half the inner diameter of the magnetizing coil in the direction away from the magnetic sensor.

In fact, an important requirement for the correct operation of the disclosed measurement probe is that the magnetic material in the detection region of the magnetic sensor is in the magnetic field area H ₃ of the magnetizing coil 3 and the magnetic field strength is inside the magnetizing coil 3. The value H ₁ does not deviate from 15%, preferably 10% or more.

  The probe holder is sufficient to avoid measurements from magnetic variations that do not occur from the magnetic characteristics of the sample, particularly to eliminate magnetic variations that occur from magnetic materials located within the far field area of the magnetizing coil. It can have the additional function of providing a non-magnetic sample support of thickness. The sample support can be any non-magnetic material such as plastic, wood, glass or the like. However, strong conductive supports such as aluminum or other metals should be avoided; they interfere with dynamic magnetic measurements due to eddy current contributions.

  Referring to FIG. 4, the proof device to be used in the method of the present invention is a magnetization value B or induction value dB / coupled to the drive (2, 6), sensing (5) and processing electronics (1). It has a measurement probe (P) for measuring any of dt. The apparatus further comprises an algorithm executed by at least one software for performing the method according to the invention. The measured magnetization or induction signal value is digitized by the A / D converter (1b) of the processor and stored in the memory (1c, 1d) as a digital value Vs. A plurality of such values Vs obtained for subsequent values of the magnetic field H finally form a digital point-to-point representation of the respective induction or magnetization curve of the sample.

  In the embodiment of the verification device according to the invention having a measurement probe coupled to the drive, sensing and processing electronics as shown in FIG. 4, the sensing and compensation inductive or field sensors 4s, 4c; 8s, 8c are measured. The electrical responses Us, Uc are each balanced (subtracted) by the balance regulator 5cs, amplified by the operational amplifier 5, and finally the digital A / D of the processor to obtain the digital sample induction or magnetization value Vs. Digitized by the D converter 1b. By obtaining a plurality of such values Vs for subsequent values of the magnetic field H, a digital point-to-point representation of the sample induction or magnetization curve can be obtained.

The proof of item 7 obtains a predetermined plurality of sample induction or magnetization values Vs, forms a sample curve portion Cs of the magnetic security material induction or magnetization (eg hysteresis) curve, and determines a predetermined comparison algorithm and a predetermined use tolerance criterion, by comparing the value of the sample curve portion Cs with the previously stored value of the corresponding reference curve portion C _R, it is achieved. The tolerance criterion here can be either a single value criterion or a combination of several conditions that must be met.

  The present invention provides a sequence of B (H) magnetization values, such as those obtainable by Hall effect or giant magnetoresistive (GMR) sensors, or certification indications for security documents or articles, such as those obtainable by induction coil sensors. Based on the use of any corresponding dB (H (t)) / dt derivative sequence of magnetic material contained in, or printed on, or applied to a security document or article as a means A method is disclosed. If H (t) is a known function of time, the derived value dB (H (t)) / dt can be obtained significantly and can be used advantageously for proof. The magnetization or inductive function of the material under test is ultimately a numerical table containing multiple (H, B) or (H, dB / dt) value pairs, or if H changes in a known manner, B Or expressed as a simple list of dB / dt values.

  The proof method according to the invention is characterized by the use of the same type of apparatus and measurement protocol to obtain reference and test sample magnetization features and thus to support "learning mode" and "test mode". Rely on. Here, the reference and test sample features are represented as a table of digital values and compared using a predetermined comparison algorithm, so that a decision about authenticity or falseness is used using a pre-established certification criterion. Derived from the result of the comparison.

  The proof method according to the present invention works well without a model and is not affected by systematic measurement errors that can occur in the proof device; therefore, the hardware of the device is more than that which requires precise absolute measurements. Remarkably easy to keep. Thus, the method of the present invention is not for measuring and comparing individual absolute physical values, but for comparing induced or magnetized “curve shapes” represented by a sequence of relative values such as those “seen” by the apparatus of the present invention. rely.

  Comparison of this sample magnetization or induced “curve shape” with the reference “curve shape” is preferably done on a point-to-point basis after curve normalization. Normalization means that both the sample and the reference curve are scaled linearly so that they have the same predetermined maximum intensity value. Given the fact that crumpling and use can reduce the amount of magnetic material present on the print, such standardization is particularly useful for concentration-independent comparisons, i.e. banknote proofs. Gives the found features. Comparing standardized magnetization or induction curves corresponds to the mere specification of such magnetic security materials, independent of the amount of material actually present on the print. Standardization has also proven useful in eliminating the effects of small distance changes between the sample and the measurement probe in the data acquisition (measurement) process.

  A comparison is a mathematical standard known in the art that subtracts the corresponding sample value from the reference value and uses the resulting difference or an amount derived therefrom as an indication for authenticity or falsehood. Can be carried out according to various methods.

  The method and apparatus of the present invention can be applied to all types of magnetic materials, whether or not they are coercive. In particular, they can be used to identify magnetic materials that have zero coercivity (ie, have no hysteresis loop) but have different magnetic saturation fields. Accordingly, various magnetic materials having different coercivity values can be identified by the method of the present invention. In addition, it is possible to use a mixture of such magnetic materials to produce a more complex dB / dt curve shape. Any curve shape can be prominently demonstrated by the method and apparatus of the present invention.

  The maximum value of the scanning field Hmax can be easily adapted to the specific application, for example as low as 100 Gauss to distinguish between different EAS materials or as high as 1 Tesla to distinguish between different hard magnetic ferrites You can choose to height.

The memory of the verification device provides space for storing one or more reference data sets to allow the device to verify (and identify) one or more different magnetic materials Can do. Furthermore, “learning mode” and “test mode” do not require implementation on the same physical device; in practice, the proof device uses a reference data set provided by a separate “reference definition device”. A sample can be provided exclusively for proof. These reference data can be downloaded into the permanent memory of the proving device, or alternatively, the reference data can be transferred to the proving device in the form of a physical memory unit containing them. It is also possible to keep the reference data in a secure location such as a safety server and upload at least one measured sample derivation or magnetization value for safe and independent comparison at the safety server.
Exemplary Embodiment According to an embodiment of a measurement probe for sensing the inductive value dB / dt, and referring to FIG. 3a, the coil body is a fiber reinforced phenolic resin with a total length of 10 mm and 30 mm. With an overall diameter of The sensing and compensating coils 4s, 4c are located inside the inner periphery at both ends of the magnetizing coil 3, and each have an inner diameter of 7.5 mm and a length of 1.5 mm. Each of these coils consists of 100 windings of “enamel” insulated copper wire of 0.1 mmΦ. The magnetizing coil 3 has an inner diameter of 10 mm and is composed of 200 wound bodies of “enamel” insulated copper wire of 0.6 mmΦ. This is placed on top of the sensing and compensation coil and fills the remaining space in the coil body. The three coil winding bodies are embedded in an epoxy resin in order to prevent instability of the coil due to mechanical or electromechanical deformation.

  According to an embodiment of the present invention, a proving device having a measuring probe P is assembled with reference to FIG. The proving device further comprises a processing device 1 embodied by ADuC812 MicroConverter (trade name) from Analog Devices. The ADuC812 chip has an 8052 microprocessor CPU 1a, a 12-bit analog / digital (A / D) converter 1b, an internal RAM, and an electrically erasable permanent EE / flash memory 1c for program and data storage. . The proving device also has a 32K external random access memory (RAM) 1d.

The verification device further comprises a voltage up converter 6 with a storage capacitor for generating the required coil driver voltage; and a triangular current ramp or simplified {+ U (Δt); −U (2Δt); + U ( Δt)} coil driver device 2 implemented as a switching bridge and driven by a microprocessor to drive the magnetizing coil 3 of the probe in a voltage sequence (where Δt is the basic time interval); and A / D of the microcontroller And a sense coil / compensation coil subtraction operational amplifier 5 which is supplied with output to the converter 1b. The input of the operational amplifier 5 is notably connected to the balance regulator 5cs, allowing fine adjustment of the compensation (“zero induction”) point. The processing electronics 1 is further connected to a mode switch _SLT for selection of the learning / test mode L / T and to a push button B for starting the measurement cycle, and also displays on / off and approval / failure status Are connected to yellow, green and red LEDs 81, 82, 83. The push button B is for turning on the main power supply Vcc of the circuit. A processor controlled power switch 9 is provided to allow the processor to maintain its own power to complete the measurement cycle and turn itself off in good condition.

  The maximum current required to drive the magnetizing coil 3 is typically on the order of 20 A or more for a 200 wound coil, producing a magnetic field on the order of 2000 gauss. The entire measurement cycle lasts on the order of 1 millisecond or less, followed by a longer waiting time, so no coil cooling is required. The electronic circuit is significantly simpler by driving the coil with a rectangular voltage sequence of the form {0 / + U (in Δt) /-(2Δt in) / + U (in Δt) / 0} provided by a simple switching device. It was found that Δt is a basic time interval selected here to be appropriately short. Under such circumstances, the current in the coil follows a substantially rectangular waveform because of the induction law d (I (t)) = (U / L) dt.

  In one example, the induction curve is sampled, digitized and stored at a rate of 200 KHz. Other faster or slower sampling rates can also be used. Raw data processing preferably can include background (zero) correction and, if necessary, noise filtering. For weak signals, the results of two or more measurement scans can be accumulated and averaged together to improve the signal to noise ratio.

According to an embodiment of the present invention, the method is carried out in the processing apparatus 1a to verify a security document or article carrying a thin layer of magnetic material with the disclosed verification device and measurement probe. This proof method is
a) Provide a digital point-to-point representation of at least part of the magnetization curve B (H) or induction curve dB (H (t)) / dt of the magnetic reference material as reference data (V _R ) in the digital memory. Process and;
b) providing a security document or article to be certified having a thin layer of magnetic material in or on at least a portion of its surface;
c) Using the verification device and measuring probe according to the invention, the magnetization curve of a thin layer of magnetic material in or on the document or article provided in step b) in the digital memory as sample data (Vs) Obtaining a digital point-to-point representation of at least a portion of B (H) or induction curve dB (H (t)) / dt;
d) processing the digital data obtained in step (c) to make corrections for the measurement-related environment;
e) Using a predetermined comparison algorithm and a predetermined tolerance criterion, the data obtained in step (d) is compared with the stored reference data provided in step (a), whereby the proof “yes” Deriving a “no” indication;
Have

According to the present invention, the same type of hardware can be used to define the reference data (V _R ) and the sample data (Vs): In “learning mode”, data from the reference sample is acquired. Are stored as reference data. In “test mode”, data from the document or article to be certified is acquired, processed, and compared with reference data to derive a true / false indication.

In the preferred example, device acquisition and test modes could be used to distinguish many different magnetic sample prints from each other. A set of four standard magnetic pigments M1-M4 with coercivity ranging from zero to 700 oersteds were mixed in different ratios as printing inks to obtain a magnetic security device:
Pigment Coercivity [Oersted]
M1: ~ 1 (soft magnetic iron)
M2: ~ 100
M3: ~ 300
M4: ~ 700
Fifteen intaglio ink samples S1 to S15 containing magnetic pigments M1 to M4 in different proportions and using a total pigment weight of 40 to 50% in the ink were prepared. The pigments were mixed to give an intaglio varnish of the type known to those skilled in the art:
M1: M M1: M3 M1: M4 M2: M3 M2: M4 Total (% by weight)
S1 1.00 40.00
S2 1.03 47.20
S3 1.00 40.00
S4 4.00 40.00
S5 4.13 42.57
S6 4.00 40.00
S7 0.25 40.00
S8 0.26 53.09
S9 0.25 40.00
S10 1.03 47.20
S11 0.26 53.09
S12 4.13 42.57
S13 1.00 40.00
S14 0.25 40.00
S15 4.00 40.00
Using a standard intaglio press and a 100 μm gravure depth engraved plate, the resulting ink was printed on paper in banknote format to obtain magnetic intaglio prints with different magnetic characteristics. All of the intaglio prints realized with these ink samples S1 to S15 could be distinguished from each other by the method and apparatus disclosed in the present invention.

Claims (13)

In a magnetic measurement probe for acquisition of magnetization data of a magnetic item (7), such as a security document or article having one magnetization coil (3), in particular having at least one magnetic print or coating,
At least two magnetic sensors (4s, 4c, 8s, 8c) are located near the magnetic poles of the magnetizing coil (3), respectively, and their magnetic axes are substantially aligned with the magnetic field inside the coil (3). Have
The magnetizing coil (3) is operable to be applied to a time-varying magnetic field,
In the magnetic measurement probe, the magnetic material M carried on the magnetic item (7) in the detection region of the magnetic sensor is further in a substantially homogeneous magnetic field area (H ₃ ) of the magnetization coil (3). As further present, it further comprises a probe holder for maintaining the magnetic item (7) at an appropriate position and distance with respect to the magnetizing coil (3) and the sensors (4s, 4c; 8s, 8c), The magnetic measurement probe is characterized in that the magnetic field strength does not deviate by 15% or more, preferably 10% or more from the value (H ₁ ) of the magnetic field strength inside the magnetizing coil (3).   The magnetic measurement probe according to claim 1, wherein the magnetizing coil is a coil without a magnetic core.   3. The magnetic measurement probe according to claim 1, wherein the magnetizing coil (3) is a cylinder coil.   The magnetic sensor is an induction sensor in the form of a sensing coil (4s) and a compensation coil (4c), respectively, and the outer diameter of the sensing coil (4s) and the compensation coil (4c) is the inner diameter of the magnetizing coil (3). The magnetic measurement probe according to claim 1, wherein the magnetic measurement probe is smaller than the magnetic measurement probe.   The magnetic sensors are magnetic field sensors in the form of a sensing element (8s) and a compensation element (8c), respectively, and the outer diameters of the sensing element (8s) and the compensation element (8c) are the inner diameters of the magnetizing coil (3). The magnetic measurement probe according to claim 1, wherein the magnetic measurement probe is smaller than the magnetic measurement probe.   6. The magnetic measurement probe according to claim 1, further comprising a sample support made of a non-magnetic material having a low conductivity. Magnetization of at least a part of the magnetic item (7) having at least one magnetic material (M), in particular a magnetic item (7), such as a security document or article, for proving said magnetic item (7) In a method for measuring features,
a) with the magnetic material (7) is disposed on the probe holder, so that the material (M) is in substantial listing homogeneity in the area H ₃ magnetization coils of the probe (3), the magnetic material (7 ) Positioning the measurement probe (P) according to any one of claims 1 to 6, wherein in the magnetic field area, the magnetic field strength is the magnetic field strength inside the magnetizing coil (3). A process that does not deviate from the value of (H ₁ ) by 15% or more, preferably 10% or more;
b) applying a time-varying magnetic field to the magnetic item (7) by the magnetizing coil (3);
c) using the magnetic sensor (4s; 4c; 8s; 8c) to measure at least one value of the magnetic characteristics of the material (M);
A method characterized by comprising:   Method according to claim 7, characterized in that the corresponding magnetization value B (Vs) of the material (M) is measured when applying the time-varying magnetic field H to the material (M).   9. Method according to claim 8, characterized in that a corresponding induced value dB / dt (Vs) of the material (M) is measured upon application of the time-varying magnetic field to the material (M). A method according to any one of claims 7 to 9,
a) providing the magnetic feature value of the magnetic reference item in the digital memory of the proving device;
b) obtaining the magnetic feature value of the magnetic item (7) in the digital memory of the proving device;
c) processing the digital data obtained in step (b) in the processing unit of the proving device so as to correct for the measurement related environment;
d) Using a predetermined comparison algorithm and a predetermined tolerance criterion, the data obtained in step (c) is converted into the corresponding stored reference data provided in step (a) and the processing device. Deriving a “yes / no” indication of the proof, thereby comparing within;
A method characterized by comprising:   The method of claim 10, wherein the reference data is obtained by the certification device. A magnetic item (7) having at least one magnetic material (M), in particular a verification device for proving at least one magnetic item (7), such as a security document,
a) the measuring probe according to any one of claims 1 to 6 and corresponding driving and sampling electronics together with it;
b) a processing device (1) with an executed algorithm for driving the probe and sampling, digitizing, processing and comparing magnetic feature values;
c) at least one memory device (1c, 1d) for storing sample and reference magnetic feature values;
Have
The proof device obtains a reference magnetic feature of the magnetic reference item (7R), obtains a “learning mode” for storing and a sample magnetic feature value from the magnetic item (7) to derive a proof signal; Support "test mode" for memorizing and comparing,
Proving device characterized by that.   Performing the comparison of the measured magnetic feature value of the sample with the corresponding previously stored reference value to derive the proof “yes / no” indication at a remote location and 13. The certification device according to claim 12, further comprising a data transfer means for transmitting back to the back.

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