EP3898248A1 - Élément de sécurité actif dans le domaine des thz et son procédé de fabrication - Google Patents

Élément de sécurité actif dans le domaine des thz et son procédé de fabrication

Info

Publication number
EP3898248A1
EP3898248A1 EP19831592.1A EP19831592A EP3898248A1 EP 3898248 A1 EP3898248 A1 EP 3898248A1 EP 19831592 A EP19831592 A EP 19831592A EP 3898248 A1 EP3898248 A1 EP 3898248A1
Authority
EP
European Patent Office
Prior art keywords
layer
security element
thz
longitudinal slots
grid structure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19831592.1A
Other languages
German (de)
English (en)
Other versions
EP3898248B1 (fr
Inventor
Hans Lochbihler
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.)
Giesecke and Devrient Currency Technology GmbH
Original Assignee
Giesecke and Devrient Currency Technology GmbH
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 Giesecke and Devrient Currency Technology GmbH filed Critical Giesecke and Devrient Currency Technology GmbH
Publication of EP3898248A1 publication Critical patent/EP3898248A1/fr
Application granted granted Critical
Publication of EP3898248B1 publication Critical patent/EP3898248B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
    • B42D25/29—Securities; Bank notes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/373—Metallic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/405—Marking
    • B42D25/425—Marking by deformation, e.g. embossing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/45—Associating two or more layers
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/003—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using security elements
    • G07D7/0032—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using security elements using holograms
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
    • G07D7/12—Visible light, infrared or ultraviolet radiation
    • G07D7/1205—Testing spectral properties

Definitions

  • the invention relates to a security element acting in the THz area for the production of ID cards, cards, passports or documents of value, such as banknotes, checks or the like, which has a lattice structure which cannot be seen with the naked eye, e.g. is formed by a metal layer.
  • the invention further relates to a method for producing such a security element.
  • the invention further relates to a document of value with such a security element.
  • Security elements are used to secure documents of value such as banknotes, checks or the like against counterfeiting.
  • Holograms are an example of open security elements.
  • a security feature in such a way that it is both an open security feature, i.e. a security feature that can be recognized by a user, and a concealed security feature that can usually only be checked with the machine by the unarmed eye and possibly by a user not even noticeable.
  • the prior art according to DE 102015009584 A1 combines open security features based on metallized sawtooth structures or color shift inscriptions or embossed structures, which are coated with a thin metal layer, with lattice structures acting in the THz region. These lattice structures have a period of approx.
  • the invention is therefore based on the object to provide a THz radiation detectable and thus concealed security element which has even more favorable properties in the THz area and requires little additional effort in series production. It should also be particularly advantageous to combine with open security features.
  • a security element for producing documents of value which has a lattice structure which cannot be seen with the naked eye and which is arranged in a dielectric, opaque layer for THz radiation, preferably a metal layer, is formed, the first layer lying in a first plane and having, for example, a layer thickness between 6 nm and 1 pm.
  • a dielectric, opaque layer for THz radiation preferably a metal layer
  • the first layer lying in a first plane and having, for example, a layer thickness between 6 nm and 1 pm.
  • the first layer is embedded in a dielectric that is transparent to THz radiation.
  • the longitudinal slots are arranged next to one another periodically or quasi-periodically with a period, for example between 8 pm and 200 pm.
  • the width of the longitudinal slots is not greater than 1/5, preferably 1/10, of the period.
  • the slots are preferably at least 5 times as long as the period.
  • a second layer is further arranged in the dielectric in a second plane, which is parallel to the first plane. This is also formed from a layer material which is opaque for THz radiation and has a second line grating structure. This is designed vertically to the first line grid structure and offset by half a period. As a result, the second line grid structure forms longitudinal webs which, when viewed from above, exactly fill the gaps left by the first longitudinal slots in the first layer.
  • the second line grid structure from parallel longitudinal webs, one of the longitudinal webs of the second layer being underneath each of the longitudinal slots of the first layer.
  • the superimposed pairs of longitudinal slots and longitudinal webs each have essentially the same width (i.e. within the scope of manufacturing tolerances, which can be 5-10%, for example), so that the gap filling mentioned is realized.
  • the distance between the first and second levels is between 50 nm and 100 pm, particularly preferably between 500 nm and 5 pm.
  • the period is more preferably in the same interval.
  • Quasi-periodic means that the grating period fluctuates around an average. This fluctuation can preferably last up to half a period, particularly preferably be up to 1/10 period. With quasi-periodic arrangement, periodic structures are covered in particular, in which the period fluctuates due to production. Such quasi-periodic arrangements of slit structures also have an increased TM transmission in the THz range.
  • the first and / or the second layer comprises a color shift coating. This improves visual recognition - in addition to the machine evaluability that takes place in the THZ area.
  • DE 102015009584 Al with security features that are visible to the naked eye are possible.
  • hologram structures, sub-wavelength gratings with periods between 200 ran and 500 nm, sawtooth structures etc. come into question here.
  • the disclosure content of DE 102015009584 A1 is fully incorporated here with regard to this.
  • a first layer is arranged in a dielectric transparent to THz radiation in a first plane, which is formed from a layer material that is opaque for THz radiation. It has a periodic or quasi-periodic, first line grid structure made up of parallel longitudinal slots, which cannot be seen with the naked eye, and which produce longitudinal slots in the first layer. A width of the longitudinal slots is not greater than 1/5 of the period, preferably not greater than 1/10 of the period.
  • a second layer is arranged in the dielectric in a second plane, which is parallel to the first plane, and is also formed from a layer material that is opaque for THz radiation. In the second shift a second line grid structure is formed. It is inverted to the first line grid structure and offset by half a period. This in turn ensures that the longitudinal webs, which are formed in the second layer, exactly fill the longitudinal slots in plan view.
  • the security element according to the invention can be checked in the THz range, since the slot structure is transparent for THz radiation with TM polarization, but opaque for TE polarization or vice versa. Due to the slit structure, the security feature acts as a polarizer that transmits THz radiation with one polarization. If the incident THz radiation is appropriately polarized, a large proportion of this polarization component passes through the security element. The security element can therefore be subjected to a machine authenticity check very easily. A THz radiation source and a THz detector are used for this. Ideally, the THz radiation is polarized, and the security element can also be recognized with unpolarized THz radiation. In this case, a polarizer that acts as an analyzer is then mandatory in front of the detector.
  • the authenticity check can be carried out with a measurement in transmission as well as in reflection.
  • the security element acts as a polarizer, which transmits the THz radiation with TM polarization. If the THz radiation is correspondingly linearly polarized, this component largely passes through the security element and is rization of the analyzer completely detected. If the polarization directions of the radiation source and detector are perpendicular to each other, the trivial case of a hole in the security element can be excluded. This could also be checked visually. If the security feature is rotated, a vertically polarized THz radiation is rotated as it passes through the security element and the analyzer with horizontal polarization can receive the THz signal.
  • the machine authenticity check can thus be carried out both with a parallel orientation of the polarization of the beam source and detector and with a crossed orientation.
  • the rotation of the security feature is a rotation of the security feature in the plane, which is defined by the longitudinal slots lying next to one another periodically or quasi-periodically.
  • the slit structure cannot be seen with the naked eye, at least for an inexperienced observer and / or in a mere plan view, since the width of the longitudinal slits is not greater than 1/5 of the period. If you lower this upper limit, the slit structure is very difficult or even impossible for an experienced observer who is looking for the slit structure and / or when using special viewing techniques (for example, certain tilting and turning of the security element) . It is particularly preferred that the width of the longitudinal slots is not greater than 1/10 of the period, since the slot structure then creates a particularly well-concealed security feature.
  • the security element is designed such that the layer comprises a plurality of fields, between which a longitudinal direction of the longitudinal slots differs.
  • the fields therefore have an individual angular orientation of their directions of the longitudinal slots. Such individual fields appear differently bright depending on the rotational position and / or orientation to the THz detector.
  • the design of the lattice structure in the layer is practically imperceptible to the naked eye.
  • a potential counterfeiter receives no indication of the presence of such a security feature.
  • the layer differs in reflection and transmission from a layer that is formed without the longitudinal slots.
  • it is possible to combine the security element with a visually visible structure e.g. in that the areas of the layer lying between the longitudinal slots are additionally provided with a further security feature which is visible to the naked eye.
  • the security element has hidden properties that can be seen with THz radiation and additional properties that can be seen with the naked eye, i. H. open security features.
  • the additional security feature perceptible to the naked eye can be, in particular, a metallized hologram, a subwavelength grating with periods from 200 nm to 500 nm, a sawtooth structure and / or a color shift coating.
  • the manufacturing method according to the invention can be designed in such a way that the described preferred configurations and embodiments of the security element are manufactured. It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations or on their own without departing from the scope of the present invention.
  • FIG. 1 is a schematic representation of a banknote with a security element
  • 3A to 7B curves to illustrate the effect of the security element of FIGS. 2A to 2D on radiation in the THz range
  • FIG. 8 shows a plan view of an embodiment of the security element with fields of different longitudinal orientation of a structure influencing THz radiation
  • FIG. 9 shows various embodiments of a field for coding hidden information with one of the security elements of FIGS. 2A to 2D.
  • 1 shows a top view of a bank note 2 which is provided with a security element 4.
  • the security element 4 is designed in such a way that it filters radiation in the THz range in a certain way and at the same time is designed such that it cannot be seen by the unarmed eye.
  • the security element 4 thus already provides a covert Si security feature that can be read out with a corresponding detector.
  • the security element 4 cannot be perceived visually as far as possible with regard to the structures that make the effect effective in the THz area, so as not to give a potential counterfeiter an indication of the presence of a structure effective in the THz area, the THz structure is in the visible wavelength range almost opaque or at least not recognizable. This does not rule out that the structure is combined or overlaid with a visually transparent structure, as is the case in the embodiments of FIGS. 2B to 2D.
  • the security element 4 can be exposed on both sides (for example when used as a fixed element spanning) and also on one side. It can also be completely embedded in the substrate transparent to THz radiation. Examples of the substrate or the dielectric are paper or plastic.
  • FIGS. 2A to 2D show a sectional view of the security element 4, which has a dielectric 6 arranged on a carrier (not designated in more detail).
  • a first line grating structure 8 is embedded, which is constructed from a THz radiation-absorbing coating, which is located in a first plane 10.
  • a second line grating structure 14 is located in the dielectric 6 in a second plane 12 lying parallel to it by a distance h, which is also constructed from a material absorbing THz radiation, preferably from the same material as the first line grating structure 8.
  • the first and the second line grating structure 8, 14 form a bi-layer grating 16.
  • the first and the second line grating structure 8, 14 are formed inverted to each other.
  • the first line grid structure 8 consists of metallic strips 18 which are spaced apart from one another by longitudinal slots 20. This structure is arranged according to a period p.
  • the second line grid structure 14 is inverted. It has longitudinal slots 24 at those locations in which the first line grid structure 8 has the strips 18 and strips 22 at the locations of the longitudinal slots 20.
  • the layer which forms the strips 18 has, for example, a thickness T1, the layer which the strips 22 forms a thickness t2.
  • the strips 18, 22, and thus the line grating structures 8, 14 have a refractive index n and are completely surrounded by the dielectric 6, which preferably and optionally above and below the line grating structures 8, 14 has the same refractive index n.
  • the refractive indices in the dielectric 6 can also vary.
  • the inverted shape which the second line grid structure 14 has for the first line grid structure 8 has the consequence that the width d of the strips 18 of the first line grid structure 8 corresponds exactly to the width of the longitudinal slots 24 of the second line grid structure 14.
  • the inverted line grids are also relatively shifted by half a period in the plane 10 or 12 in such a way that a top view of the security element 4 2A (according to the direction of sight in Fig. 2A from top to bottom) a gap-free layer by the stripes fen and 22 is formed.
  • FIG. 2A shows that a plane wave falls on the security element 4 at an azimuth angle ph and an elevation angle th.
  • This incident radiation S is partly transmitted as transmitted radiation T tiert and partially reflected as reflected radiation R.
  • the properties of this effect on radiation in the THz range are explained in more detail below with reference to FIGS. 3 to 7.
  • FIGS. 2B to 2D differ from those of FIG. 2A by the configuration of the strips 18. They are used to additionally generate a visually perceptible effect. Despite this visually perceptible effect, the structure effective in the THz area cannot be recognized. The covert security feature is therefore retained. In this context it is expressly referred to
  • the structure described above for authenticity detection in the THz area is preferably produced on film substrates and can then be applied, for example, to bank notes 2.
  • a metallic reflecting surface is not very attractive to an observer. It is possible to overprint this area.
  • Known metallized security features such as holograms, micromirror arrangements or metallic sub-wavelength grids, are primarily human features that are difficult to check authentically by machine. By superimposing these structures with the THz feature described above, a mechanical check of these structures in the THz area is possible.
  • an overlay with various known metallized Si security features is therefore advantageous.
  • Such an overlay can with embossed holograms, as shown schematically in Fig. 2B. 2B, the strips of the first line grating structure 8 consist of a hologram structure 26. It is opaque for THz radiation, so that the hidden security property of the security element 4 is retained.
  • Such holograms consist of grating arrangements with periods of approximately 500 nm to 1500 nm.
  • the grating profile has a sinusoidal shape or a rectangular shape with pitch of approximately 100 nm to 300 nm.
  • the structure is metallized over the entire surface. Aluminum, silver or copper with layer thicknesses of approximately 30 nm to 80 nm are preferably used as metals.
  • the overlay with the THz structure described above means that narrow periodic regions of the embossed hologram or mirror strip lie on the lower level 12. Since the period of the hologram grating is significantly smaller than the grating period of the THz structure, there is no additional interaction in the THz area with this structure. Because the period of the hologram is orders of magnitude smaller than the wavelength of the THz radiation. There is therefore a comparable transmission in the THz range as in the bi-layer grating 16 described above.
  • the stripes include a color shift coating 28, which can optionally also be applied to the stripes of the second line grid structure 14.
  • the color shift coatings 28, 30 produce a visually perceptible effect. Since they comprise a metal layer or another coating opaque for THz radiation, the effect of the security element 4 as a concealed security feature is also preserved here.
  • the color shift structure consists, for example, of a semi-transparent chrome layer, a dielectric spacer layer, preferably made of silicon dioxide, and a metallic mirror layer located underneath, e.g. B. aluminum. This layer structure is finally designed as a bi-layer structure 16. det. The area of the underlying structure is small compared to the total area. Therefore, the visual impression of these security features is hardly affected by the overlay with the THz structure.
  • the strips of the first line grid structure 8 are designed as a sawtooth structure 32. So there is an overlay with a saw tooth structure such.
  • Known sawtooth arrangements have a lateral extent between 1 mhi and 10 mha at a height between approximately 0.3 mih and 4 mih. Such arrangements are used to create movement and spatial effects in reflection. They are either covered with a simple metal layer or they are vapor-coated with a so-called color shift structure in order to additionally create a color effect.
  • the metallized structure is interrupted by the periodic arrangement of the longitudinal slots 20, below which the strips 22 lie on the lower plane. In the THz range, only this combination has an effect on the transmission, since the interaction with the sawtooth structure 32 itself is low.
  • the superimposition can also be carried out with (optical) sub-wavelength structures. These are 1-dimensional or 2-dimensional periodic gratings with periods between 100 nm and 500 nm, which are metallized. It should be mentioned that so-called metallic moth eye structures, which can serve as an absorbent background, can also be overlaid with the structure explained above. In addition, the metallized ridges are raised instead of recessed as in the above drawings. The transmission in the THz range is identical in this vertically mirrored arrangement. Furthermore, the above-mentioned THz radiation-absorbing coatings are not restricted to a simple metal layer or color shift structures. Other multilayer layers can also be used, as long as they are opaque to THz radiation - either in combination or due to an absorbent component or a layer.
  • the effect of the security element 4 on radiation in the THz range that is to say on radiation between, for example, 1 and 12 THz, is explained below using the example of the security element in FIG. 2A. Since the visually perceptible structures of the stripes of the first line grid structure 8 in the embodiments according to FIGS. 2B to 2D have no effect on the effect in the THz range, the embodiments also apply analogously to this.
  • the other parameters are identical to those of Figures 3A-C.
  • the figure labeled A shows the transmission for TM polarization
  • the figure labeled B shows the transmission for TE polarization
  • the figure labeled C shows the contrast.
  • a variation in the height distance h does not have a significant effect on the transmission behavior in the THz range.
  • the polarization properties are hardly influenced. This means that the process window in series production is not critical with regard to this parameter.
  • 5A and 5B that the spectral characteristic of the transmission is shifted towards low frequencies for increasing periods.
  • FIG. 7A shows the spectral transmission in the range from 0.1 to 3 THz for TM and TE polarization.
  • the degree of polarization was calculated from this and shown in FIG. 7B.
  • the structure is in here embedded a UV-curable embossing lacquer with a refractive index of 1.4.
  • the measurement confirms the previously presented properties of the bi-layer grating 16.
  • the unexpected high transmission is also present for superimposed grating structures.
  • the blocking effect for TE polarization is slightly lower for this sample. However, this is due to small defects in the sample through which the THz radiation penetrates unhindered. Nevertheless, the degree of polarization of the sample is high.
  • the bi-layer grating 16 superimposed in the hologram can be reliably detected.
  • this approach can be used to encode information that can be automatically evaluated in the THz area.
  • An example is the coding of the denomination or the value of banknotes, e.g. B. 5, 10, 20, 50 and 100.
  • These numerical values can be encoded by differently oriented areas of bi-layer gratings, preferably with areas rotated by 90 °.
  • FIG. 9 shows a plurality of coding fields 50-56 with a vertical longitudinal slot direction.
  • the security element 4 can be manufactured on an industrial scale by known methods. The essential steps in the positioning are: a) embossing the structure in UV varnish on foils,
  • the longitudinal slots 20 are formed by the corresponding embossed structure as depressions, and the metal is also deposited in the depressions in order to form the strips 22 there.
  • the security element can simply be subjected to an authenticity check by examining its polarization properties for radiation in the THz spectral range. Possible devices are shown in FIGS. 13 and 14 of DE 102015009584 A1.
  • the security feature 4 acts as a polarizer that transmits THz radiation with TM polarization. If the THz radiation is correspondingly linearly polarized, this component largely passes through.
  • the THz source can be followed by a polarizer; this can be omitted if the THz source already emits the corresponding polarized radiation. After passing through the security element 4 z. B.
  • an analyzer which filters the direction of polarization accordingly for the THz detector.
  • the contrast can be enhanced in two or more different polarization directions, ie the device is first set in the configuration with the same orientation of source radiation and detector and then with an orthogonal orientation to one another. If the security element has 4 areas with differently oriented slot structures, a spatially resolving detector measures different intensities for the individual areas. This increases the reliability of the authentication of this feature.
  • a THz radiation source and a THz detector are used, which are arranged opposite one another.
  • the security element 4 is located in between and is preferably irradiated approximately vertically.
  • the radiation from the THz beam source is preferably linearly polarized and the detector is also sensitive to polarization.
  • the security element 4 is arranged in such a way that TM polarization is present for at least one area of the bi-layer grating 16 and the THz radiation reaches the detector there almost unimpeded. In contrast, the transmission for the lattice areas is blocked in TE polarization.
  • the polarization directions of radiation source and detector are perpendicular to one another.
  • the trivial case of a hole in the security element can be excluded, through which the THz radiation would also pass unhindered.
  • a perpendicularly polarized THz radiation is rotated as it passes through and the analyzer with horizontal polarization can receive the THz signal.
  • the THz analysis can be carried out at a single frequency or in a single frequency band as well as for several frequencies or separate frequency bands. The latter two embodiments refine the authenticity check.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Computer Security & Cryptography (AREA)
  • Business, Economics & Management (AREA)
  • Accounting & Taxation (AREA)
  • Finance (AREA)
  • Credit Cards Or The Like (AREA)

Abstract

L'invention concerne un élément de sécurité pour réaliser des documents de valeurs tels que des billets de banque, des chèques ou analogues. Dans un diélectrique (6) transparent au rayonnement THz, dans un premier plan (10) est disposée une première couche qui est formée d'une matière opaque au rayonnement THz et forme une première structure de réseau de lignes (8) périodique ou quasipériodique non reconnaissable à l'œil nu, faite de fentes longitudinales (20) parallèles entre elles, produisant des interstices dans la première couche, la largeur des fentes longitudinales (20) n'étant pas supérieure à 1/5 de la période (p), de préférence pas supérieure à 1/10 de la période (p). Dans le diélectrique (10), dans un second plan (12) qui est parallèle au premier plan (10), est disposée une seconde couche qui est également faite d'une matière opaque au rayonnement THz et forme une seconde structure de réseau de lignes (14) qui est inversée par rapport à la première structure de réseau de lignes (8).
EP19831592.1A 2018-12-17 2019-12-13 Élément de sécurité actif dans le domaine des thz et son procédé de fabrication Active EP3898248B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102018132516.9A DE102018132516A1 (de) 2018-12-17 2018-12-17 Im THz-Bereich wirkendes Sicherheitselement und Verfahren zu dessen Herstellung
PCT/EP2019/000339 WO2020126065A1 (fr) 2018-12-17 2019-12-13 Élément de sécurité actif dans le domaine des thz et son procédé de fabrication

Publications (2)

Publication Number Publication Date
EP3898248A1 true EP3898248A1 (fr) 2021-10-27
EP3898248B1 EP3898248B1 (fr) 2023-02-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19831592.1A Active EP3898248B1 (fr) 2018-12-17 2019-12-13 Élément de sécurité actif dans le domaine des thz et son procédé de fabrication

Country Status (4)

Country Link
EP (1) EP3898248B1 (fr)
CN (1) CN113195239B (fr)
DE (1) DE102018132516A1 (fr)
WO (1) WO2020126065A1 (fr)

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DE102015010191A1 (de) * 2015-08-06 2017-02-09 Giesecke & Devrient Gmbh Sicherheitselement mit Subwellenlängengitter
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WO2020126065A1 (fr) 2020-06-25
EP3898248B1 (fr) 2023-02-08
CN113195239A (zh) 2021-07-30
CN113195239B (zh) 2022-09-27

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