EP3999355A1 - Signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui émet dans le domaine spectral infrarouge - Google Patents

Signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui émet dans le domaine spectral infrarouge

Info

Publication number
EP3999355A1
EP3999355A1 EP20734880.6A EP20734880A EP3999355A1 EP 3999355 A1 EP3999355 A1 EP 3999355A1 EP 20734880 A EP20734880 A EP 20734880A EP 3999355 A1 EP3999355 A1 EP 3999355A1
Authority
EP
European Patent Office
Prior art keywords
security feature
phosphor
feature according
security
basic
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.)
Pending
Application number
EP20734880.6A
Other languages
German (de)
English (en)
Inventor
Roland HEISE
Oliver Muth
Starick Detlef
Thomas JÜSTEL
Viktor Anselm
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.)
Bundesdruckerei GmbH
Original Assignee
Bundesdruckerei 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 Bundesdruckerei GmbH filed Critical Bundesdruckerei GmbH
Publication of EP3999355A1 publication Critical patent/EP3999355A1/fr
Pending legal-status Critical Current

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
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/378—Special inks
    • B42D25/382—Special inks absorbing or reflecting infrared light
    • 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
    • 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
    • B42D25/378—Special inks
    • B42D25/387—Special inks absorbing or reflecting ultraviolet light
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7756—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing neodynium
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7756—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing neodynium
    • C09K11/7758—Aluminates; Silicates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7774—Aluminates

Definitions

  • Security feature for a security or value document with at least one fluorescent substance which can be excited in the ultraviolet spectral range and which emits in the infrared spectral range
  • the invention relates to a security feature for a security or value document, with at least one luminescent material which can be excited in the ultraviolet spectral range and which emits in the infrared spectral range after excitation has taken place.
  • the invention relates to a security or value document with a security feature according to the invention.
  • Luminescent organic and / or inorganic materials have long been used in diverse ways as security features in security and value documents, such as banknotes, passports, ID cards, driver's licenses, etc., but also in product protection.
  • luminescent security features are known from the technical and patent literature, which are used in different ways as copy protection and / or for the authenticity verification of value and security documents. It is also known to combine linearly and / or band-shaped emitting phosphors to form security features that exclusive luminescence codes can be assigned to the resulting complex emission spectra.
  • luminescence The electromagnetic radiation emitted by a physical system during the transition from an excited state to the ground state is referred to as luminescence.
  • luminescence relates to the conversion of higher-energy radiation into lower-energy radiation (down-conversion), the difference between the wavelength of the absorbed radiation and the wavelength of the emitted radiation being referred to as the Stokes shift.
  • different types of luminescence for example photoluminescence, cathodoluminescence, X-ray luminescence, electroluminescence etc.
  • anti-Stokes luminescence up-conversion
  • IR infrared
  • Phosphors are organic or inorganic chemical compounds which show luminescence phenomena when excited by electromagnetic or particle radiation or when excited by means of electric fields.
  • the basic phosphor grids (phosphor matrices) formed by the chemical compounds act as radiation centers Activator ions and, if necessary, additional coactivator ions incorporated.
  • These phosphors are often in the form of solids, in particular in the form of luminescent pigments.
  • the wavelength range of the electromagnetic radiation which is arranged between that of the X-rays and that of the microwaves is referred to as optical radiation. It thus includes the range of UV radiation, that of visible light and that of infrared radiation and thus the wavelength range between 100 nm and 10 6 nm (1 mm).
  • UV radiation relates to the wavelength range from 100 to 380 nm.
  • Visible light is that section of the electromagnetic spectrum that can be perceived by the human eye. For the normal observer, this range covers the wavelengths between 380 and 780 nm.
  • NIR near infrared
  • medium 3000 nm to 50 mm
  • far IR 50 mm to 1 mm
  • An emission spectrum describes the spectral intensity distribution of the electromagnetic radiation emitted by the phosphors at a fixed excitation wavelength.
  • Such an emission spectrum can consist of emission lines and / or emission bands.
  • An excitation spectrum illustrates the dependence of the intensity of the radiation emitted by a phosphor at a fixed wavelength on the wavelength of the excitation radiation.
  • the measured intensity is influenced by both the efficiency for the absorption of the excitation radiation and the efficiency of the radiation conversion.
  • UV radiation sources are available for UV excitation, including easy-to-use handheld devices, for example in the form of UV-emitting LEDs.
  • the acquisition of the NIR luminescence signals can take place with the aid of the same sensors that are also used for the detection of visible radiation.
  • comparatively inexpensive silicon detectors are preferred, which are characterized by the fact that they have their greatest spectral sensitivity in the range between 800 and 950 nm.
  • the emissions in the NIR range also form or contain machine-readable security codes that could be used for authenticity verification, nominal value coding or, if necessary, also for sorting, for example, different banknote denominations or value products.
  • the invention is thus based on the technical problem of providing a security feature which has a high level of protection against forgery or a high level of security and which at the same time can be verified with relatively little technical effort.
  • One aspect of the invention relates to a security feature for a security or value document, with at least one luminescent substance which can be excited in the ultraviolet spectral range and which emits essentially in the infrared spectral range after being excited.
  • another aspect of the invention relates to a security or value document with a security feature according to the invention.
  • a preferred embodiment of the invention relates to a security feature in which the selected phosphors emit in the near infrared spectral range at wavelengths from 780 nm to 3 mm and preferably in the wavelength range from 800 nm to 950 nm, and where the at least one phosphor is preferably doped with trivalent neodymium activator Ions (Nd 3+ ) and trivalent chromium sensitizer ions (Cr 3+ ).
  • ions which, due to their electronic structure, can be expected to act as activators in suitable basic lattices, after excitation with a higher-energy UV radiation, emissions in the preferred NIR spectral range, in particular between 800 to 950 nm.
  • the possible activators include the trivalent neodymium ions (Nd 3+ ), although these ions are characterized by the fact that they only have 4f-4f transitions in almost all basic lattices in the specified energy range for excitation, which is forbidden by quantum theory, which leads to that the efficiency of the spectral excitability and thus also that of the luminescences resulting from the excitation is extremely low. For this reason, it is preferred to find suitable sensitizer ions, which in turn are able to effectively absorb the excitation radiation and then transfer it to the Nd 3+ activator ions with a likewise high efficiency.
  • An advantageous embodiment of the invention therefore comprises a security feature that is based on the use of novel, specially configured Phosphors based in the UV-A range (for example in the UV-C range between 200 nm and 280 nm and / or in the UV-B wavelength range between 280 nm and 315 nm and / or preferably in the UV-A spectral range between 315 and 380 nm) and which have at least two emission peaks that are spectrally closely spaced in the NIR range, preferably in the range between 800 and 950 nm.
  • the preferred luminescence properties could be realized in particular through the combination of Nd 3+ activator and Cr 3+ sensitizer ions and through the selection of suitable basic lattices.
  • the surprisingly high efficiency of the energy transfer between the Cr 3+ and Nd 3+ ions results in luminescence intensities that ensure reliable detection.
  • the phosphor classes particularly suitable for generating UV-excitable emissions in the NIR range between 800 and 950 nm include, in particular, Cr 3+ - and Nd 3+ - codoped basic lattice materials with a garnet structure, or correspondingly co-activated aluminates or gallates, which have a magnetoplumbite Structure and special tungstates, which are also referred to as double perovskites with regard to their structural classification in specialist literature.
  • the basic lattice materials used for the phosphor configuration are known in principle from different types of technical applications.
  • the magnetoplumbites of the form SrGa 12 O 19 , SrAI 2 O 19 , LaMgAl 11 O 19 (LMA) were described as fluorescent host lattices as early as 1972 and 1974 in the work presented by JMPJ Verrisonen (Verêten 1972, Verstegen 1974), with these being used for doping in the case of excitation with 254 nm radiation, pigments which finally emit in the visible range were primarily Mn 2+ , but also Eu 2+ - TI + Ce 3+ and Tb 3+ ions, or combinations of these activators.
  • Garnet-based phosphors which are doped differently and luminescent under different excitation conditions are also known.
  • Special designs are the phosphors Y 3 Al 5 O 12 : Cr 3+ , Nd 3+ (garnet), SrAI 12 O 19 : Cr 3+ , Nd 3 + , LaMgAlnO 19 : Cr 3+ , Nd 3+ and SrGa 12 0i 9 : Cr 3+ , Nd 3+ (each magnetoplumbite) and Ca 2 MgWO 6 : Cr 3+ , Nd 3+ (double perovskite).
  • the preferred phosphor classes can be identified by the general formulas listed below:
  • a preferred embodiment of the invention relates to a security feature in which the at least one phosphor has a garnet-phosphor basic grid and can in particular be described by the general formula (Ln 1-x Ndx) 3 (M 1-y Cr y ) 5 O12 .
  • Ln here preferably stands for one of the two rare earth elements yttrium (Y) and / or lutetium (Lu), although these elements can also be completely or partially replaced by the elements lanthanum (La) and / or gadolinium (Gd), while M takes precedence denotes the elements aluminum (AI) and / or gallium (Ga), which can also be at least partially substituted by scandium (Sc).
  • the relations 0 ⁇ x ⁇ 0.2 and 0.005 ⁇ y ⁇ 0.4 or preferably the relations 0.01 ⁇ x ⁇ 0.1 and 0 apply, 01 ⁇ y ⁇ 0.06.
  • the at least one phosphor represents a magnetopium bit of the general formula (EA 1-x Nd x ) (M 1-yx / 12 Cr y / ⁇ / x / 12 ) i 2 0i 9 .
  • EA is used for the elements calcium (Ca), strontium (Sr), barium (Ba) and lead (Pb), which are wholly or partly as
  • the letter M here again primarily symbolizes the elements Al and / or Ga, while N preferably stands for the elements magnesium (Mg) and / or zinc (Zn), which are inserted into the grid for the purpose of charge compensation.
  • Mg magnesium
  • Zn zinc
  • the advantageous concentrations of the activator and sensitizer elements can be determined by the relationships 0 ⁇ x ⁇ 0.2 and 0.005 ⁇ y ⁇ 0.1 or preferably by the relationships 0.02 ⁇ x ⁇ 0.1 and 0.02 ⁇ y ⁇ 0.06 can be described.
  • the at least one phosphor comprises a magnetopium bit of the type (Ln 1-x Nd x ) N (M 1-y Cr y ) 11 O 19 .
  • Ln preferably denotes one of the rare earth elements La and / or Gd
  • N again primarily denotes the elements Mg and / or Zn and M are in turn used primarily to identify the elements Al and / or Ga.
  • the concentrations of the activator and sensitizer elements are in the range from 0 ⁇ x ⁇ 0.2 or from 0.005 ⁇ y ⁇ 0.1 and preferably in the range from 0.02 ⁇ x ⁇ 0.1 and 0.02 ⁇ y ⁇ 0.06 are set.
  • Yet another advantageous embodiment of the invention relates to a security feature in which the at least one phosphor has a double perovskite structure and is given by the general formula (EA 1-3X Nd x Na x2 ) 2 (Mg1. 3y Cr y Li 2y ) W0 6 , is marked.
  • EA is used again to identify the elements Ca and / or Sr and / or Ba, the elements sodium (Na) and lithium (Li) act as charge compensators and the indices to identify the advantageous concentration ranges for the activator and sensitizer element values meet the conditions 0.001 ⁇ x ⁇ 0.1 and 0.001 ⁇ y ⁇ 0.1 or, in a particularly preferred manner, the conditions 0.005 ⁇ x ⁇ 0.03 and 0.005 ⁇ y ⁇ 0.04.
  • tungstates of the form AI2W3O12, LiLuW 2 0 8 and Ba 6 Lu 2 W 3 0i 8 can also be selected as further preferred basic lattices for the formation of Cr 3+ and Nd 3+ codoped phosphors.
  • the list of possible host lattices for the provision of Cr 3+ - and Nd 3+ - co-activated luminophores that can be excited in the ultraviolet spectral range and emit effectively in the NIR range does not represent a restriction. Rather, further classes of material or individual compounds can also be included in the selection of the inorganic solid-state compounds suitable as the basic phosphor lattice.
  • Another preferred embodiment of the invention relates to a security feature that not only contains a single inventive phosphor, but also comprises multiple phosphors in the form of phosphor combinations, these multiple phosphors having different basic grids and wherein all the phosphors forming the security feature and the corresponding phosphor combinations can be excited in the ultraviolet spectral range and emit after excitation in the infrared spectral range, in particular in the near infrared spectral range (NIR) in a wavelength range from 780 nm to 3 mm, preferably in the wavelength range from 800 nm to 950 nm.
  • NIR near infrared spectral range
  • Another preferred exemplary embodiment of the invention relates to a security feature in which the several inventive phosphors which have been put together to form phosphor combinations and which have different basic lattices are characterized by an essentially identical or similar aging resistance.
  • the same or similar aging resistance is particularly advantageous because on this basis it can be achieved that the emission properties of the security features equipped with such phosphor combinations do not change over a longer period of use, which means that the emission spectrum and thus the ratios of the intensities of the individual emission lines and / or emission bands of such a security feature are essentially retained over the life cycle of the corresponding security and value documents.
  • An advantageous embodiment of the invention relates to a security feature in which the at least one phosphor or the multiple phosphors combined to form phosphor combinations in one or more ultraviolet wavelength range (s), in particular in the wavelength range between 200 nm and 280 nm (UV-C range) and / or in the wavelength range between 280 nm and 315 nm (UV-B) and / or preferably in the UV-A spectral range between 315 and 380 nm and wherein the resulting infrared emission spectra include several individual emission lines and / or emission bands, the maxima of which are preferred are only a few nanometers apart.
  • UV-C range the wavelength range between 200 nm and 280 nm
  • UV-B wavelength range between 280 nm and 315 nm
  • UV-A spectral range between 315 and 380 nm
  • luminescence codes can be assigned to the infrared emission spectrum of the at least one inventive phosphor or to the emission spectrum of the combination of several phosphors, which are formed by the spectral sequence of selected emission lines and / or emission bands.
  • These security codes which can preferably be read out by machine, can be used for authenticity verification, nominal value coding or also for sorting, for example of different banknote denominations or value products.
  • An alternative or supplementary embodiment of the invention relates to a security feature in which the at least one phosphor or the phosphors combined to form phosphor combinations have mean grain sizes of approximately 5 nanometers to approximately 15 micrometers.
  • Luminescent security features can preferably be used on, on or in different security or value documents (for example bank notes, ID cards, passports, driver's licenses, etc.) or in product protection.
  • security or value documents for example bank notes, ID cards, passports, driver's licenses, etc.
  • the selected Cr 3+ and Nd 3+ codoped phosphors forming the security feature can be applied or attached, for example, with the help of conventional printing technologies (gravure, flexographic, offset or screen printing processes, etc.) or by using different types of coating processes
  • the materials to be coated can consist of paper, different plastics or also of other organic or inorganic substances.
  • Yet another preferred exemplary embodiment of the invention relates to a security feature that can be used, for example, to secure the authenticity of banknotes, ID cards, passports, driver's licenses, etc., and further information, for example about the position and / or shape of the security feature, is assigned to the security feature.
  • the security feature can have a specific contour, for example in the form of a symbol, a number or a pictogram.
  • Fig. 1 the emission spectra of preferred exemplary embodiments for three Cr 3+ -
  • Fig. 2 Excerpts from the emission spectra according to the
  • Embodiments 1 to 3 obtained Cr 3+ - Nd 3+ codoped phosphors with a magnetoplumbite structure after UV excitation with a 365 nm UV radiation source,
  • Fig. 3 a comparative representation of the excitation spectra of the NIR
  • Luminescence of the inventive phosphors provided on the basis of the exemplary embodiments 1 to 3,
  • Fig. 1 shows the emission spectrum 11 of a preferred embodiment 1, which relates to a magnetoplumbite phosphor of the type (EA 1-X Ndx) (M 1-yx / 12 Cr y N X12 ) 12 O 19 , the specific composition of the exemplary Strontium gallate phosphor can be described by the formula Sr 0.96 Nd 0.04 Ga 11, 36 Cr0 60 Mg 0.04 O 19 .
  • the sample is ground and then sieved.
  • FIG. 1 shows a further emission spectrum 12 for a further exemplary embodiment 2 of a Cr 3+ - Nd 3+ - codoped strontium aluminate phosphor with a comparable magnetopium bit structure.
  • 0.1417 g (0.960 mmol) SrC0 3 0.0067 g (0.020 mmol) Nd 2 0 3 , 0.5852 g (5.740 mmol) Al 2 O 3 , 0.0365 g (0.240 mmol) Cr 2 O 3 and 0.0025 g (0.040 mmol) MgF 2 mixed and homogenized with the addition of acetone.
  • the annealing process again comprises two stages, first the batch mixture is annealed for two hours in the presence of atmospheric oxygen at 1000 ° C., followed by a further thermal treatment at 1600 ° C. for 8 h under otherwise identical annealing conditions.
  • the usual process steps for sample preparation and grain size adjustment correspond to those which were also used in the case of the first exemplary embodiment.
  • the phosphor has the composition Sr 0, Nd 0, Al 11.48 Cr 0 , 48 Mg 0 , 04 .
  • the annealing material is ground intensively between the individual heating steps.
  • the resulting phosphor is characterized by the formula La 0.96 Nd 0.04 MgAl 10.45 Cr 0.55 O 19 . 1 shows the emission spectra 11, 21 and 31 of the Cr 3+ -Nd 3+ codoped described in the three exemplary embodiments 1, 2 and 3
  • Magnetoplumbite phosphors when excited by a 365 nm UV radiation source.
  • these emission spectra have intense luminescence in the NIR range between 840 and 940 nm and between 1020 and 1120 nm.
  • the exemplary inventive phosphors are primarily characterized by two narrow-band emissions between 850 and 880 nm and between 880 and 920 nm.
  • characteristic differences are recorded for the spectral emission maxima and the intensity ratios between the individual emission lines or bands of the various phosphors.
  • the selected magnetopium bit and additionally equipped according to the invention with Cr 3+ sensitizers, as well as, for example, the corresponding codoped garnet or other preferably used phosphors in the spectral range from 250 to 700 nm have a very high absorption strength.
  • FIG. 3 illustrates the excitation spectra 12, 22 and 32 for the NIR emissions occurring in the spectral range between 890 and 910 nm of the Cr 3+ - Nd 3+ -codoped magnetoplumbit- obtained according to embodiments 1 to 3 Phosphors are shown in summary.
  • these excitation spectra essentially consist of three distinguishable excitation bands. Two of these bands with their maxima between 400 and 500 nm and between 500 and 600 nm are primarily positioned in the visible spectral range, with the first mentioned excitation band extending into the near UV range. These gangs can electronic transitions from the 4 A 2 ground state of Cr 3+ into the excited states 4 T 1 ( 4 F) or 4 T 2 ( 4 F) can be assigned.
  • Another excitation band comprises the UV range 230-350 nm responsible for the absorption in this spectral electronic transition is generally in the literature as 4 A 2 -. 4 indicates T1 (4 P) junction.
  • the excitation spectrum 12 for the linear 896 nm luminescence of a Cr 3+ - Nd 3+ - codoped strontium gallate phosphor according to embodiment 1 is the excitation spectrum 13 of a basic lattice material activated exclusively with Nd 3+ ions with otherwise compared with the same composition. Both excitation spectra were recorded under identical measurement conditions.
  • FIG. 5 shows the excitation spectrum 42 of a corresponding phosphor configured in accordance with exemplary embodiment 4.
  • the Cr 3+ - Nd 3+ - codoped tungstate phosphor produced in accordance with exemplary embodiment 5 has a broad excitation band in the UV range between 230 and 380 nm, the intensities of which are those of the excitation bands that are also present in the visible Significantly exceeds the spectral range.
  • Preferred tungstate phosphors with a particularly high spectral excitability in the UV range also have a tendency to develop two excitation maxima. From this fact it can be concluded that in these - in the context of the invention - particularly advantageous Cr 3+ - Nd 3+ - codoped luminophores, in addition to electronic transitions of the form 4 A 2 - 4 T- 1 ( 4 P), so-called band-band -Transitions are responsible for absorption in the ultraviolet spectral range.
  • the excitation spectrum 43 likewise recorded in FIG. 5, of a tungstate phosphor synthesized according to exemplary embodiment 4 but activated exclusively with Nd 3+ ions illustrates this finding.
  • the corresponding excitation spectrum also has an absorption band with a maximum at around 290 nm, which could possibly be assigned to such a band-to-band transition .
  • the extract 41 shown in FIG. 6 from the emission spectrum of an exemplary tungstate phosphor according to embodiment 4 shows that the spectral distances between the maxima of the individual lines are mostly only a few nanometers.

Abstract

L'invention concerne un signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui, une fois l'excitation effectuée, émet dans le domaine spectral infrarouge. L'invention concerne en outre un document de sécurité ou de valeur présentant un signe de sécurité selon l'invention.
EP20734880.6A 2019-07-19 2020-06-19 Signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui émet dans le domaine spectral infrarouge Pending EP3999355A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102019119687.6A DE102019119687A1 (de) 2019-07-19 2019-07-19 Sicherheitsmerkmal für ein Sicherheits- oder Wertdokument, mit mindestens einem Leuchtstoff, der im ultravioletten Spektralbereich anregbar ist und der im infraroten Spektralbereich emittiert
PCT/EP2020/067231 WO2021013448A1 (fr) 2019-07-19 2020-06-19 Signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui émet dans le domaine spectral infrarouge

Publications (1)

Publication Number Publication Date
EP3999355A1 true EP3999355A1 (fr) 2022-05-25

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP20734880.6A Pending EP3999355A1 (fr) 2019-07-19 2020-06-19 Signe de sécurité pour un document de sécurité ou de valeur, présentant au moins une substance luminescente qui peut être excitée dans le domaine spectral ultraviolet et qui émet dans le domaine spectral infrarouge

Country Status (3)

Country Link
EP (1) EP3999355A1 (fr)
DE (1) DE102019119687A1 (fr)
WO (1) WO2021013448A1 (fr)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19803997B4 (de) * 1998-02-02 2018-01-25 Giesecke+Devrient Currency Technology Gmbh Wertdokument
US7122248B2 (en) * 2001-02-21 2006-10-17 Honeywell International Inc. Security articles
KR101280751B1 (ko) 2004-09-02 2013-07-05 방크 드 프랑스 발광 특성을 갖는 가치 증서
EP1647946A1 (fr) 2004-10-14 2006-04-19 Giesecke & Devrient GmbH Système de documents de valeur
DE102010000559A1 (de) * 2010-02-25 2011-08-25 Bundesdruckerei GmbH, 10969 Verfahren zur Verifikation von Sicherheits- oder Wertdokumenten mit einem Anthrachinon-Farbstoff
CN102205761A (zh) * 2011-03-28 2011-10-05 上海印钞有限公司 一种防伪安全文件及安全文件的检测方法
US20130048874A1 (en) * 2011-08-31 2013-02-28 Honeywell International Inc. Articles with confounded emission characteristics and methods and apparatus for their authentication
DE102012111054B4 (de) * 2012-11-16 2023-10-19 Bundesdruckerei Gmbh Sicherheitselement für ein Wert- und/oder Sicherheitsdokument

Also Published As

Publication number Publication date
WO2021013448A1 (fr) 2021-01-28
DE102019119687A1 (de) 2021-01-21

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