DE102010010072A1 - Marking device and method for color marking value or security documents - Google Patents

Abstract

The invention relates to a marking device (1) for a value or security document (2) and to a method for permanent, in particular individual multi-colored marking of security and / or security documents (2). The method for colored permanent marking of a value or security document (2) comprises the steps of: providing a document body (40) comprising regions of different colors, wherein the individual regions are each monochrome; Providing a marking device which comprises at least one laser light source (5) for generating laser light (6) and a light guide device (8, 8 ') which is coupled to the at least one laser light source (5) so that a focus (19) of the laser light (6) the laser light source (5) can be positioned in a controlled manner on or in the document body (40) of the value or security document (2); iteratively targeted positioning of the focus (19) on or in the document body (409 and irradiation of the laser light (6 ')) to selectively locally change the color of one or more of the areas, so that the document body (40) then a multi-color color impression in a Irradiation of white light to a human observer, wherein the laser light (6) is irradiated by short or ultrashort laser pulses having a plus duration of less than 100 ps or less than 10 ps, whereby non-linear interactions between the material of the value This makes it possible to use or produce an improved focusing of the laser light (6 ') and thereby a higher density of the colored markers defining the color, so that a higher color intensity is achieved is feasible.

Description

The invention relates to a method for multicolor marking value or security documents and a marking device, which are designed for a permanent colored marking a value or security document by means of laser light.

Security documents are those documents and objects that are protected by at least one security feature or security element against corruption and / or unauthorized copying. Security documents that embody a value are also referred to as value documents. Security documents include, for example, identity documents, driver's licenses or motor vehicle papers and documents of value, with value documents, for example banknotes, postage stamps or checks.

At least in some of the security documents or value documents, it is advantageous to be able to mark these permanently, preferably individually. Different methods are known from the prior art, with which value and / or security documents can be marked individually. Historically, most value and security documents have been paper-based and, in particular, have been customized by means of printing techniques, modern security documents and value documents are often at least partially made from plastic materials. Modern identity cards and driver's licenses are joined together, for example, as lamination bodies comprising a plurality of plastic layers and optionally one or more paper layers.

For the permanent individual marking of plastics so-called laser marking methods have been developed in the prior art. For this purpose, individual plastic layers, which are to be marked later with a laser, special pigment substances added. These do not affect transparency in the visible optical range or are not or barely perceptible to a user. If such a layer is irradiated with laser light of sufficient intensity, an increased absorption of the laser light occurs at the pigments. This makes it possible to couple energy into the otherwise transparent plastic, which then leads via the amount of energy deposited here to a local coloring, for example via heating and a partial carbonization of the plastic material. Depending on the amount of energy applied, a degree of blackening of the plastic can be set in a targeted manner. From individual local pixels, patterns, in particular grayscale images, lettering and other characters, can be permanently marked in the value or security document.

For a long time, however, the goal has been pursued to highlight the value or security document in color, preferably multi-colored. Ideally, a full-color marking should be possible, which can represent colors from a gamut, which is spanned by preferably three primary colors, such as red, blue and green.

From the DE 100 11 486 A1 a card-shaped data carrier is known, consisting of at least one layer in which visually readable information in the form of a change in optical properties due to an irreversibly caused by a laser beam material change are introduced, the absorption capacity of this layer for at least one wavelength due to the laser radiation at least partially is reduced. In this process, original colored or opaque layers are "bleached" in terms of absorption.

From the DE 30 48 733 A1 For example, an identification card and a method for producing such an identification card with applied information in the form of patterns, for example letters, numbers and / or images, are known. The identification card has layer areas of different colors arranged one above the other on at least one surface, which are at least partially interrupted by visually recognizable personalization data. It is envisaged that the information is displayed by the action of a controlled laser beam on one or more layers of paint applied to one another on a plastic carrier. As a result of the laser irradiation, the color can be changed locally.

From the DE 696 05 788 T2 For example, there is known a method of producing an article having a colored mark by irradiating the surface of the article with laser light in the form of the mark, the article being comprised of a plastic composition containing at least three color-forming components in at least the area where the mark is applied which lose their color-forming ability under the influence of laser light selected and present in a concentration such that at each wavelength between 400 and 700 nm at least a portion of the amount of incident light is absorbed, one or more colors for the character are selected, the wavelength of the laser light is set in the sequence to a value which depends on the selected color, and the surface of the object is then irradiated with the laser light.

From the WO 01/28778 A2 is a method for applying colored characters on a data carrier, preferably made of plastic, known by means of a laser system, wherein in at least one surface layer and / or near-surface layer of the data carrier introduced latent pigments, which takes place by energetic excitation, a change in the absorption behavior of the for the character provided areas of the disk by laser irradiation, which is in the IR and / or visible range, energetically excited so that the same pigments color change takes place and that after the color change of the laser-irradiated latent pigments, not excited by laser irradiation latent pigments be energetically excited in such a way by irradiation with light waves in the UV wavelength range, that in the so-irradiated pigments colorlessness is brought about.

From the DE 100 53 264 A1 a method for writing data, in particular personalization data, on and / or in a data carrier by means of electromagnetic radiation is known, wherein the method any data carrier is provided on and / or in which at least one colorant is provided at least locally, and this colorant is irradiated by means of the electromagnetic radiation of at least one wavelength range, so that there is a change in the color of the colorant by bleaching in the region of the irradiation, wherein the color change can be determined by machine and / or by a human eye. This results in an increased security against counterfeiting and manipulation for the data carrier.

From the DE 199 55 383 A1 a method for applying colored information to an object is known, wherein the article has at least in a near-surface layer at least two different coloring particles that change the color of this layer under the influence of laser radiation, wherein the laser radiation is used with at least two different wavelengths, In order to change the color of this layer, the application of laser radiation to the object in the vector and / or raster method via a Zweikoordinatenstrahlablenkeinrichtung and a focusing device for focusing the laser radiation is applied to the layer of the object. At least one beam guiding means is provided for guiding a first laser beam having the wavelength λ ₁ and at least one further laser beam having a wavelength λ ₂ different from the wavelength of the first laser beam via the two-coordinate beam deflecting means and the focusing means to the layer of the object , For the Zweikoordinatenstrahlablenkeinrichtung an arrangement of two mutually perpendicular axes rotatably mounted deflecting mirror is proposed. A focusing is done by a fixed plan field optics. Since the light does not pass through the planar field optics on the optical axis, chromatic aberration effects occur in the focusing device. In particular, if differently colored laser light is used for marking, this requires a complex compensation.

From the DE 10 2006 014 367 A1 For example, a data carrier and a method for its production are known. The data carrier comprises a visually or machine recognizable marking in the form of a pattern of letters, numbers or pictures. In the method of manufacture, a data carrier with a data carrier substrate is provided and a marking layer is applied to the data carrier substrate. The marking is introduced into the marking layer by means of short laser pulses.

In a group of the prior art methods which allow a colored marking, different colorants are incorporated in the value or security document, which conjointly cause a color impression in a human observer via an additive or subtractive color mixture. In the unmarked state, a uniform color impression is produced over the entire surface. By locally targeted change of individual colorants, the color mixture changes, so that locally creates a desired color impression. The practical problem of the prior art methods is to achieve high-contrast intense hues.

It is an object of the invention to provide an improved method and apparatus for permanently color marking value or security documents that eliminate or reduce disadvantages of the prior art.

The object is achieved by a device with the features of claim 1 and a method with the features of claim 9. Advantageous embodiments of the invention will become apparent from the dependent claims.

Basic idea of the invention

The basic idea of the invention is to carry out the marking of the value and / or security document with laser light, which is generated by a short-pulse laser source. This means that the individual laser light pulses used for marking have a pulse duration of less than 100 picoseconds, preferably less than 10 picoseconds. This makes it possible the To make interaction with the material of the document body or the colorants contained therein so that a change of the material and / or the colorant wholly or largely takes place without a thermal interaction. Since the coupling of the energy occurs in a short time window and the process caused by the interaction proceeds so quickly that no or only a very small dissipation of the energy takes place in the form of heat away from the interaction site, the change is well localized. Adjacent to the interaction site, there is no change in the material of the security or security document or the colorants contained therein. This possibility of selectively performing local marking for the purpose of local color change at densely adjacent locations, ie with high areal resolution without affecting the colourfulness of neighboring locations, allows high contrast and / or intense color impressions to be created for a pattern marked in a document body.

definitions

A security element is a structural unit comprising at least one security feature. A security element can be an independent structural unit which can be connected, for example glued, to a security document, which can also be a value document. It can also be an integral part of a security document. An example of the former is a so-called holopatch (a hologram patch, such as a hologram film section) adhered to a banknote, or a visa stickable to a security document. An example of the latter is a diffractive surface relief embossed in an identity document.

A security feature is a structure that is only producible or reproducible with (compared to simple copying) increased effort or not at all unauthorized, or makes forgery and / or falsification visually and / or mechanically recognizable.

By way of example, security documents may include identity cards, passports, ID cards, access control cards, visas, tax stamps, tickets, driving licenses, motor vehicle papers and documents of value, which in particular include banknotes, checks, postage stamps and credit cards, and any chip cards and self-adhesive labels (eg product assurance). Security documents, which also embody a value, are also referred to as value documents. A sharp distinction between these two terms is often not possible. A credit card, for example, represents a security document protected by security features and security elements against counterfeiting and falsification, which does not directly represent a value beyond the pure material value of the card, but makes it possible to dispose of large assets.

A pulsed laser is a laser that, in contrast to a continuous wave or CW laser that continuously emits laser light, emits laser light in temporally limited portions called pulses. As a short pulse laser is understood here a laser that generates light pulses whose pulse duration is less than 100 picoseconds. The literature also speaks in part of ultrashort laser pulses, with no uniform definition for this. Ultrashort pulses are pulses whose pulse duration is less than 10 picoseconds.

An optical fiber is a fiber made of a transparent material, at the interface of which total reflection can cause conduction of light in the interior of the fiber.

A fiber laser is a laser whose active medium in which light-induced emission of electromagnetic radiation occurs is an optical fiber.

A pattern typically consists of a multiplicity of juxtaposed pattern units or pixel dots. The pattern units or pixels of a pattern are associated with one another and arranged laterally in a defined manner, typically in one or two spatial dimensions, and overall give a representation, for example a picture, a symbol, a logo, a lettering (letters, numbers, alphanumeric characters) or a code (eg a barcode). An individualization pattern is a pattern that is used for individualization. In a colored pattern, a pixel may include a plurality of sub-pixels, each of which is monochrome and determine a coloration of the pixel as a whole via a color addition or color subtraction.

Individualizing is a pattern when it is unique to a person or an object or a group of persons or objects from a largest set of persons or objects. For example, a code individualizing a group of persons within the total population of a country is the city of residence. An individualizing for a person code, for example, the number of the identity card or passport photo. A code individualizing a group of bills within the total amount of bills is the value. Individualizing for a banknote is the serial number. Non-individualizing is a pattern that applies to all elements of a Entity is identical. For bills this is for example a coat of arms, which is printed on all banknotes.

A basic pattern is an array of monochromatic areas or sub-areas thereof, which, with appropriate modification of the colors of the areas or sub-areas thereabove, permits marking of a multicolor pattern.

Colored is an entity that causes a color impression when viewed by a human. Multicolor is an entity that produces at least two distinguishable color impressions. Monochrome, on the other hand, is an entity when it produces a single color impression.

Colorants are all entities responsible for causing a color impression via emission or absorption of light in the visible wavelength range.

The light of a Planckian radiator, which produces a continuous spectrum in the visible wavelength range, is regarded here as white light. Natural sunlight is an example of white light.

Preferred embodiments

In particular, there is provided a method of multicolor marking value or security documents comprising the steps of:
Providing a document body comprising areas of different colors, each area being monochromatic;
Providing a marking device, which at least one laser light source for generating laser light and
a light guide device coupled to the laser light source such that a focus of the laser light of the laser light source is positionally controllable on or within the document body of the value or security document;
iteratively selectively positioning the focus on or in the document body and irradiating the laser light to selectively locally change the color of one or more of the areas such that the document body subsequently produces a multicolor color impression upon irradiation of white light to a human observer;
wherein the laser light used for marking is irradiated by means of short or ultrashort laser pulses having a plus duration of less than 100 ps or less than 10 ps.

A marking device for multi-colored marking of value or security documents thus comprises:
at least one laser light source and
a light guide device coupled to the laser light source so that laser light of the laser light source can be positioned controlled on a value or security document,
wherein the laser light source is a short pulse laser source or ultrashort pulse laser source that generates laser pulses having a pulse duration of less than 100 ps or less than 10 ps. In addition to purely optical focusing, the achievable resolution in the case of methods according to the prior art is generally limited with regard to the marking produced by the fact that the interaction between the laser light and the security document is based on thermal effects. This can be avoided by using laser light from short-circuit lasers.

Iterative targeted positioning of the focus on or in the document body and irradiation of the laser light comprises repeatedly irradiating light several times successively at the same focus position relative to the document body as well as repeatedly irradiating light, the position of the focus being relative to the material to the surface of the document body and / or perpendicular to the surface of the document body is varied. A variation of the focus position perpendicular to the document surface alters a selection of a plane parallel to the surface of the document body in which the focus is positioned.

One advantage of using short-pulse laser light is that intensity densities can be achieved with this laser light, so that non-linear optical interactions can also be triggered. This makes it possible, for example, to produce markings with a higher resolution, since thermal interaction processes, which are always associated with a dissipation of the heat into surrounding areas and cause a resolution limitation over it, can be avoided.

An embodiment of the invention thus provides that the local change in the color of a region is made via a non-linear interaction with the irradiated laser light.

In order to create a multicolored color impression, for example to mark a full-color colored passport image in a security document, in one embodiment at least three regions of different colors are provided with each other in a basic pattern of nested sub-regions or arranged in the basic pattern when provided. The at least three areas can thus be divided into many, usually regularly arranged sub-areas. Being part of an area are the subareas viewed, which have the same color. The subregions may be two-dimensional area or three-dimensional volumes. For example, such a basic pattern can be printed by printing using different inks on a substrate layer. Likewise, it is also possible in a further embodiment to print the subregions on different substrate layers comprising the subregions of the different substrate layers making up the document body by stacking the substrate layers and then assembling, for example in a lamination process, one another with respect to a viewing direction parallel to the direction of lamination , do not overlap or largely do not overlap.

In order to produce a desired color impression, an exact positioning of the laser light on or in the document body is necessary to selectively correct the individual subregions with regard to their color. As a result, a falsification or marking with not provided hardware is made much more difficult.

Particularly preferably, the document body comprises at least three areas of different color, each having a base color of a color system, which spans a multicolor gamut. Thus, with a suitable choice of the primary colors in the document information can be encoded, which can use almost the entire human-perceivable color space.

In a preferred embodiment, the subregions that are not or at least not completely overlapping with respect to a normal of a surface of the document body are arranged such that they represent a Bayerpattern prior to marking. This makes it possible to mark a pattern composed of regularly arranged pixels which, with regard to the usable colors, can use almost the entire perceptible color space. With regard to their assignment to the at least three regions and the arrangement relative to one another, the subregions are optimally adapted to the sensitivity of the human eye, so that over a maximum of four markings of subregions, one image pixel each can be generated which produces any color impression from the gamut spanned by the primary colors causes.

In order to be able to store the color information in a plane of the value or security document via the markings, in one embodiment the Bayerpattern is or is printed on a substrate layer surface. This is or is preferably formed as an inner substrate layer surface, so that a manipulation is difficult.

According to a further embodiment, the colored areas in the form of layers which overlap one another in a planar manner are introduced into the document body or are thus introduced during the provision.

In one embodiment, the markings are made by removing material. Here, cavities are introduced into the document body from the surface. A depth of the cavities in the document body determines which color impression is produced on the document body at the location of the cavity. By using short pulse laser light or ultrashort pulsed laser light, the cavities can be formed so close to each other that the remaining material does not cause color degradation of the entire marked pattern as in the prior art. Because the edge surfaces of the cavities can be formed smoothly and perpendicularly to the surface of the document body (with perpendicular irradiation of the laser light), web widths of the document body remaining between adjacent cavities can be minimized. As a result, intense color patterns can be generated which are not impaired by the color of the web areas.

In order to achieve a high localization of the individual markings, in one embodiment the focusing of the laser light is made such that a diameter of an interaction region of the non-linear interaction of a laser pulse in an image plane perceived by the human user is in the order of magnitude of less than 100 μm, more preferably smaller 20 microns, most preferably in the order of 5 to 15 microns.

The local change in the color of a region can be made by changing the colorant causing the colorant by means of the non-linear interaction.

Particularly advantageous short laser pulses with pulse durations in the range less than 100 picoseconds, preferably in the range of 100 femtoseconds to 10 picoseconds, can be generated with a fiber laser. Compared with other solid state lasers fiber lasers have the advantage that they can be constructed very compact and have a high electro-optical efficiency. In addition, fiber lasers are much more modest in terms of adjustment and handling than most known solid state lasers.

An advantage of using short laser pulses with pulse durations of less than 100 picoseconds, preferably less than 10 picoseconds, is that a very precise spatial confinement of the interaction zone between the laser light and the material of the security or security document can be achieved non-linear optical interaction effects can be used to form the label. A preferred embodiment of the method therefore provides that the marking is triggered via a non-linear optical effect in the value or security document.

In an embodiment, it is provided that the light-guiding device comprises a relative to the value and / or security document movably mounted optical fiber, which is coupled to at least one drive means so that the laser light via a movement of an exit surface of the optical fiber in a positioning plane relative to the value - And / or security document can be positioned laterally on the value or security document. The laser light of the laser light source is thus guided by means of an optical fiber, and a positioning of the laser light on the value or security document to be marked takes place by moving the exit surface of the optical fiber relative to the value or security document. Compared to the prior art, there is the advantage that the laser light used for marking with a suitable orientation of the positioning plane relative to a surface of the security or valuable document, preferably parallel thereto, respectively at the same angle, preferably perpendicular, to the value and / or security document incident and beyond a path length of the traveled light path is the same regardless of the illuminated lateral position on the security and / or security document. This makes it possible to focus the laser light used stronger and yet to use an identical focus extension at the marking at all lateral positions of the value or security document. Problems that are known due to a slightly different direction of irradiation in the guide devices of the prior art, can thus be avoided.

To achieve a high resolution in the marking, a good focus is advantageous. For this purpose, a focusing optics can be used. It is preferred, a focusing optics, if used, to couple with the respective exit surface of the optical fiber. This means that the focusing optics is moved by means of the drive device together with the exit surface of the optical fiber. The advantage is that the light path through the focusing optics is the same in each case, regardless of the position on or in the value or security document that is being marked.

Different implementations are possible in order to specifically set a focus position in the value or security document.

In one embodiment, the focusing takes place by means of the Kerr effect. In this case, the focal length of the material of the focusing lens changes due to the non-linear interaction of the electromagnetic radiation with the material of the lens. The focal length of the lens is inversely proportional to the intensity of the electromagnetic radiation in a Gaussian radiation profile.

In an embodiment in which the light guide is performed by means of an optical fiber, it is provided that in addition to the movement in the positioning plane, which is usually oriented parallel to a surface of a plane security document, a movement of the exit surface of the optical fiber is possible to vary a light path between the exit surface and a surface of the document. This can be used to vary a focus position within the value or security document. Such a change in direction can be achieved, for example, in one embodiment in that the exit surface, from which the laser light is rectilinearly guided on the document surface, in addition to the movement in the positioning plane, which is parallel to the surface of the value or security document, perpendicular to the Positioning level or the surface of the value or security document is movable.

In other embodiments, for example, where the exit surface is moved in the positioning plane together with an imaging and / or focusing optic to position the exiting laser light laterally on the surface of the asset or security document, a change in the light path may occur, for example, in some embodiments be achieved that the exit surface of the optical waveguide in addition relative to elements of the imaging and / or focusing optics, such as a deflection mirror, in the positioning plane is relatively movable. Thus, on the one hand, a positioning laterally on the document via a movement of the exit surface together with the imaging and / or focusing optics is possible and additionally by a relative movement of the exit surface relative to the imaging and / or focusing optics in the positioning plane a change in the focus position perpendicular to Surface of the value or security document possible.

In a further embodiment, the focusing optics consists of a piezoelectric material. By applying voltage that can Material deformed and thus the focal length of the material can be adjusted.

In a preferred embodiment, the laser light source is integrated in the optical fiber. As a result, any coupling losses are reduced in the coupling into the fiber. Thus, a compact and simple construction is possible. Compared with solid-state lasers, for example Ti: sapphire lasers, fiber laser systems do not require expensive cooling and achieve a high electro-optical efficiency. Furthermore, laser light of different wavelengths can be generated by parametric tuning with the same hardware. This is effective with fiber lasers.

In order to enable a faster marking of the value or security document, it is provided in a further development of the invention that the light guiding device comprises at least one further movable, preferably even more, further movably mounted optical fibers. This makes it possible, at the same time at several points or at the same time with different wavelengths of light to attach a mark on the security or security document or bring in the value or security document. If different wavelengths of light are used, then each optical fiber can be provided with a focusing optics adapted to the corresponding wavelength of light. It should be noted that with pulse durations of more than 10 ps it is still possible to speak of a defined wavelength. At pulse lengths shorter than 10 ps, the spread due to the Heisenberg uncertainty principle is significant. For example, the blur at a pulse of 10 ps is about 0.41 meV, which corresponds to about 0.12 nm at a wavelength of 620 nm (2 eV). At pulse durations of 10 fs, the blur is about 0.41 eV, which means at a wavelength of 620 nm (2 eV) that the bandwidth is at least 125 nm.

In a preferred embodiment of the invention, the exit surface of the at least one optical fiber is positionable relative to the at least one further optical fiber or optionally relative to the plurality of exit surfaces of the plurality of optical fibers in the positioning plane. Particularly preferably, the plurality of optical fibers or their exit surfaces are individually driven in the positioning plane and can be positioned relative to one another. It goes without saying for the person skilled in the art that there are mechanical residual actions since the optical fibers can not penetrate one another and thus can not be arranged at one and the same position at the same time.

If a plurality of optical fibers are present, then the focus position within the value or security document along a normal to the surface of the security document can be set individually for them in one embodiment. This can be targeted markings in different levels or layers, from which the value or security document is joined, are introduced. Preferably, this is controlled possible.

The features of the method according to the invention have the same advantages as the corresponding features of the marking device according to the invention.

The invention will be explained in more detail with reference to preferred embodiments with reference to a drawing. Hereby show:

1 a schematic representation of a marking device for value or security documents;

2 a schematic representation of a document body for introducing a colored marking;

3 a schematic representation of a marked document body;

4 a schematic representation of a beam profile in focus;

5 a schematic representation of a basic pattern; and

6 another embodiment of a marking device.

In 1 is schematically a marking device 1 to permanently mark a value or security document 2 shown. The value document 2 is on a bracket 3 arranged. This can be the value or security document 2 by means of a transport device 4 supplied and / or discharged from this. In some embodiments, it is possible that the transport device 4 the holder 3 formed. The person skilled in various devices for transporting value or security documents are known. Usually the marking of the value or security document becomes 2 carried out after this is completed to the mark still to be attached. However, it is also possible to make the mark before the value or security document 2 is completely finished, for example, before it is separated from a bow or a strip.

The marking device 1 includes a laser light source 5 , The laser light source 5 is formed, laser light 6 to create. The laser light source 5 is a pulsed light source. For example, it may be a solid-state laser, for. A Ti: sapphire laser. To the value or security document 2 to mark, the laser light must be 6 targeted on the value or security document 2 ie on its surface 7 or inside the value or security document 2 to be positioned. For this purpose, a light guide device 8th intended. The light guide device 8th includes an optical fiber in the embodiment described herein 9 into which the laser light 6 is coupled. An exit surface 10 the optical fiber 9 becomes in a positioning plane 11 emotional. The positioning level 11 In a preferred embodiment, it is parallel to the surface 7 value or security document 2 educated. Around the exit surface 10 in the positioning plane 11 to be able to move or position, is the optical fiber 9 with a drive device 12 coupled. The drive device 12 includes an X-axis actuator in the illustrated embodiment 13 , a Y-axis actuator 14 and a Z-axis actuator 15 , These are connected and aligned so that the X-axis actuator moves the exit surface 10 the optical fiber 9 parallel to an x-axis 16 , the Y-axis actuator 14 parallel to a Y-axis 17 and the Z-axis actuator 15 parallel to a Z-axis 18 causes. It should be noted that a movement parallel to the Z-axis is a change of the positioning plane 11 causes. About the drive device 12 It is thus possible, a position of a focal point 19 of the exit surface 10 exiting laser light 6 ' along a normal to the surface 7 value or security document 2 to position. A movement of the exit surface 10 in the positioning plane 11 causes a lateral alignment and positioning of the exit surface 10 exiting laser light 6 ' or the focal point formed thereby 19 , It should be noted that other embodiments may have and use differently configured light guiding devices.

In some embodiments it is provided that with the exit surface 10 the optical fiber 9 an imaging and / or focusing optics 20 is coupled. This is done with the exit surface 10 the optical fiber moves. In some embodiments, the exit surface is 10 the optical fiber designed so that the exiting laser light 6 ' is focused and no or a complementary focusing optics is necessary.

About the introduced at the respective position in the value or security document amount of energy, which can be varied for example via a pulse intensity or a number of introduced at the same position light pulses, the color of the mark or its color impression caused regulated. About the drive device 12 it is possible to make a marker vectorial (but broken into individual pixels (marker points)) or in the grid.

A distance 27 the positioning level 11 from the surface 7 or the value or security document 2 In some applications, the marking does not have to be varied. Then reaches a positioning 8th which only has one X-axis actuator 13 and a Y-axis actuator 14 includes. It is understood by those skilled in the art that for the positioning of the exit surface 10 the optical fiber 9 in the positioning plane 11 It is also possible to use a set of actuators which do not cause any movements parallel to the coordinate axes, but which are capable of interacting with the exit surface 10 in the positioning plane 11 to position laterally flat at different locations.

It is understood by those skilled in the art that the light exit surface 10 in the positioning plane 11 not in all embodiments must be positionable so that all locations on the surface of the document with the exiting laser light 6 ' can be illuminated. The laser light only needs to be positionable at those positions on the asset or security document at which markings are to be made. If only a limited area of the value or security document is provided for a marking, then a positioning area adapted to this area is also sufficient 26 in which the exit surface 10 the optical fiber 9 is positionable.

In 2 is an exemplary embodiment of a document body 40 a value or security document 2 shown, which is suitable for introducing a colored marking. The document body 40 is designed as a lamination body. In the production of a carrier film 41 , a black foil 42 , a blue foil 43 , a green foil 44 , a red foil 45 and a clear, ie transparent cover sheet 46 layered on top of each other. These are then subsequently joined together in a lamination process using heat and pressure to form the monolithic document body 40 together. Preferably, the films 41 - 46 all made of the same thermoplastic material, such as polycarbonate or polyvinyl chloride. Additional security elements can be placed between the slides 41 to 46 be inserted. In addition, individual or all foils may be printed.

The black foil 42 , the blue foil 43 , the green foil 44 and the red foil 45 each represent monochrome areas, each of which has a different coloration than the others. Blue, red, green represent the basic colors of an RGB color system. The gamut of the RGB color system makes it possible to display full-color objects. Around black in a simple way, a black foil is additionally provided.

For example, using a cyan yellow magenta (black) color system (CYM (K) color system) one would substitute for the blue film 43 a cyan foil, instead of the green foil 44 a yellow foil and instead of the red foil 45 Use a magenta foil.

The order of the slides can also be chosen differently. Preferably, the films 41 - 45 opaque designed. As a result, a color space comparable to the normal printing systems is clamped, since only the uppermost color layer is always visible. As a result, standard systems can be used to optimize the color space. In a transparent embodiment of the films 41 - 45 a corresponding adjustment of the colors is necessary, since in this case all remaining color layers characterize the color impression. As a result, the generation but also the falsification or adjustment is much more difficult.

Based on 3 The introduction of a colored marking will now be explained by way of example. Schematically is a document body 40 similar to the post 2 shown. The same technical features are identified by the same reference numerals throughout the application. The document body 40 contains instead of the cover foil 46 over the red foil 45 a barrier film 47 , This is, for example, opaque and white. Above the barrier film 47 is a protective film 48 arranged, which is laminated, for example, after the colored marking.

Before inserting a mark, the document body appears 40 when viewed under natural daylight (white light) white. Short or ultrashort laser light pulses become cavities 51 - 54 in the different slides 47 . 45 . 44 . 43 brought in. A depth of the cavities 51 - 54 Defines the color impression of a surface 7 locally at the location / position of the respective cavity 51 - 54 having. The cavities 51 and 54 in each case pass completely through the white barrier film and into the red film 45 , Thus, a red color impression is communicated locally. At the cavity 52 is also the red foil 45 completely permeated. The cavity 52 ends in the green foil, so that locally a green color impression is conveyed. The cavity 53 ends in the blue foil 43 , All overlying films are completely pierced. It is generated locally a blue color impression.

The depth of the cavity can via a choice of deposited energy over one or more short or ultrashort laser pulses, a choice of the depth of focus, an adjustment of the wavelength of the laser or pulses to the color of the respective film to be removed 43 - 45 . 47 be selectively varied.

A cross-sectional shape of the cavities can be controlled by a choice of beam profile as well as a sidewall shape of the cavities. Factors influencing this are the depth of focus and the defocusing of the laser beam and optionally a Kerr effect present in the document material, which can lead to additional focusing or defocusing of the beam.

Due to the short pulse duration and the achievable high light intensities non-linear interactions can be exploited, so that in the document body 40 no thermal effects occur which lead to a dissipation of energy in the document body and, in this case, to less precisely defined cavity cross-sectional shapes. In particular, the possibility of cavities almost perpendicular to the surface 7 value or security document 2 or the document body 40 oriented side walls 55 to produce cavities targeted at short intervals 56 . 57 in the document body 40 contribute. Remaining bars 58 between the cavities 52 - 54 are thus from the surface 7 Consider small area flat, so that a high density of points and thus resolution of the information shown on the markers is possible. In addition, the remaining lands affect a color intensity less than in the prior art. It goes without saying that for a macroscopic flat color impression of a viewer, the color addition or color subtraction by the individual cavities 51 - 54 caused local color impressions are responsible.

The subsequently applied protective film 48 protects the cavities 51 - 54 during use of the document body 40 as a value or security document 2 , Also an introduction of other cavities to falsify the value or security document 2 is at least made more difficult because this also damage the protective film 48 would effect.

If non-linear interactions are exploited, the shape of the beam profile can be used to achieve a focus which is smaller than the focusing of the laser light. This is below based on 4 explained.

The individual components of the marking device are controlled by a controller 22 controlled so that the mark is executed automatically. The controller 22 only data are supplied which contain the pattern for the marking, so that the corresponding areas of the value or security document 2 be irradiated with a corresponding laser light intensity to the corresponding marking in the value or security document 2 to effect.

The embodiment according to 1 is characterized by the fact that the laser light 6 is produced as pulsed laser light with short pulse durations of less than 100 ps, preferably less than 10 ps. As a result, an exploitation of non-linear optical effects for introducing the markings on or in the value or security document is possible.

By using the fiber optic fiber 9 for guiding the laser light 6 ' on or in the value or security document 2 can be a path 27 between the light guide device 8th and the value or security document 2 be kept low. This can be selected in the range from contact to a few cm, preferably 0.2 to 10 mm. This makes it possible to form the beam guide strongly divergent and to focus sharp. Thus, a very narrow focusing can be achieved both transversely to the beam direction (propagation direction) and along the beam direction.

With a suitably chosen intensity and suitably selected beam profile, a non-linear interaction is achieved only in a "core region" of the beam of the laser light in focus. As a result, an even closer to the geometric light focusing light focusing is achieved. As a result, both laterally (transversely to the direction of irradiation of the laser light 6 ' as well as longitudinally, that is in the propagation direction of the laser light 6 ' an improved resolution can be achieved when marking. For example, micro-writing can be realized with a character size in the range of a few micrometers.

In 4 is a so-called beam profile 61 shown schematically in focus. A light intensity I is plotted against the position r transversely to the propagation direction (z direction in FIG 1 ). (r, for example, becomes parallel to the x-axis according to 1 chosen.) It is assumed here that a beam profile 61 of the laser light 6 ' (to 1 ) in focus 19 (to 1 ) has a Gaussian profile. Since nonlinear interactions of the square I ² 62 If the intensity I of the laser light is dependent, that is to say a so-called I ² dependency, the non-linear interaction only takes place in the core region if the pulse intensity is suitably selected 63 of the steel profile, in which the square I ² 62 the intensity I of the beam profile 61 a threshold 64 exceeds. As a result, the focus extension of the mark becomes an extension 65 of the core area 63 fixed and not by extension 66 of focus 19 of the laser light 6 ' , the extension of the beam profile 61 equivalent.

In another embodiment, the regions having different colors are introduced into the document body in the form of subregions. The subregions are arranged so that these subregions form a predetermined pattern when viewed on a surface of the document body. As a given pattern, for example, a Bayer pattern 81 can be used, which exemplarily in sections 5 is shown. Per colored pixel 82 The information to be marked here are each four sub-areas 83 intended. A subsection 83-r is red and a subsection 83-b is blue, two sub-areas 83 g1 . 83-g2 are green.

The individual subareas 83 are preferably arranged in a plane of the document body parallel to a surface of the document body. For example, the subareas 83 be printed on a surface. It is also possible that the subsections 83 are printed on different surfaces of foils, which are so collected and assembled or are that the individual sub-areas are arranged in the register and give the predetermined pattern.

The colored marking takes place by the subregions 83 by means of the short or ultrashort laser pulses of less than 100 ps or less than 10 ps, preferably of 100 fs-10 ps, are modified in color. The sizes and the distances of the individual sub-areas 83 can be chosen so that they are smaller than the focus size of the laser light pulses. Targeted modification of the color, for example by removing the ink causing the color or by "destroying" the pigments causing the color in the corresponding subregion, can be achieved by utilizing nonlinear interactions. By means of a suitable choice of the beam profile, it is thus possible to obtain and utilize a focusing of the interaction region which is improved compared to the optical focusing of the laser light.

Thus, for example, information in the form of micro-writing can be color-coded into a value or security document for individualizing it.

It will be understood by those skilled in the art that as an alternative to a Bayer pattern, other patterns may also be used that allow a variety of different color impressions to be achieved via color addition or color subtraction, with appropriate modification of the subregions.

In 6 is another embodiment of a marking device 1 shown schematically. Technically equivalent features are provided with identical reference numerals. The illustrated embodiment differs from that according to 1 in that the light guide device 8th in this embodiment, two optical fibers 9 . 9 ' includes. These are correspondingly each with a drive device 8th respectively. 8th' coupled, which is analogous to the drive device 8th to 1 are formed. This embodiment offers the advantage that the value or security document 2 can be marked simultaneously or quasi simultaneously in several places.

The laser light source 5 is in this embodiment as a fiber laser 23 with a seed laser 24 and an amplifier ring 25 shown schematically. It will be understood by those skilled in the art that another laser light source may be used with this embodiment. Likewise, a fiber laser 23 as a laser light source 5 in the embodiment according to 1 be used.

LIST OF REFERENCE NUMBERS

1

marking

2

Value or security document

3

bracket

4

transport device

5

Laser light source

6, 6 '

laser light

7

surface

8, 8 '

Lighting device

9, 9 '

optical fiber

10, 10 '

exit area

11

positioning level

12, 12 '

driving means

13, 13 '

X-Achsenaktor

14, 14 '

Y Achsenaktor

15, 15 '

Z-Achsenaktor

16

X axis

17

Y-axis

18

Z-axis

19

focus point

20

Imaging and / or focusing optics

22

control

23

fiber laser

24

Seed laser

25

amplifier ring

26

positioning

27

distance

40

document body

41

support film

42

black foil

43

blue foil

44

green foil

45

red foil

46

cover sheet

47

barrier film

48

protector

51-54

wells

55

Side wall

56, 57

distances

58

Stege

61

beam profile

62

Square of intensity (I ² )

63

core area

64

threshold

65

Extension of the core area

66

Extent of focus

81

Bayer pattern

82

Pixel (of information)

83

subfield

83-r

Subsection (red)

83-b

Subsection (blue)

83-g1, 83-g2

Subsection (green)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10011486 A1 [0006]
• DE 3048733 A1 [0007]
• DE 69605788 T2 [0008]
• WO 01/28778 A2 [0009]
• DE 10053264 A1 [0010]
• DE 19955383 A1 [0011]
• DE 102006014367 A1 [0012]

Claims (9)

Method for multicolor marking value or security documents ( 2 ) comprising the steps of: providing a document body ( 40 ) comprising areas of different colors, each area being monochrome; Providing a marking device which has at least one laser light source ( 5 ) for generating laser light ( 6 ) and a light guide device ( 8th . 8th' ) associated with the at least one laser light source ( 5 ), so that a focus ( 19 ) of the laser light ( 6 ) of the laser light source ( 5 ) on or in the document body ( 40 ) of the value or security document ( 2 ) is positionally controlled; iterative targeted positioning of the focus ( 19 ) on or in the document body ( 409 and irradiation of the laser light ( 6 ' ) to locally change the color of one or more of the areas, so that the document body ( 40 ) subsequently produces a multicolored color impression upon irradiation with white light for a human observer, characterized in that the laser light ( 6 ) is irradiated by short or ultrashort laser pulses having a plus duration of less than 100 ps or less than 10 ps. A method according to claim 1, characterized in that the colored areas in the form of layers which overlap one another in the document body ( 40 ) are introduced or introduced during the provision. Method according to claim 1 or 2, characterized in that the document body ( 40 ) comprises at least three regions of different colors, each having a base color of a color system comprising a multicolor gamut. A method according to claim 3, characterized in that the at least three regions of different color are provided with each other in a pattern of nested sub-areas or are arranged during the provision. A method according to claim 4, characterized in that the pattern as Bayerpattern ( 81 ) is or is formed. Method according to one of claims 1 to 5, characterized in that the local change of the color of a region via a non-linear interaction with the irradiated laser light ( 6 ' ) is made. Method according to one of claims 1 to 6, characterized in that the local change of the color of a region is made by changing the color-causing colorant by means of the non-linear interaction. Method according to one of claims 1 to 7, characterized in that the focusing of the laser light is made such that a diameter of an interaction region of the non-linear interaction of a laser pulse in an image plane perceived by the human user in the order of magnitude of less than 100 microns, more preferably smaller 20 microns is. Marking device ( 1 ) for color marking value or security documents ( 29 comprising at least one laser light source ( 5 ) and a light guide device ( 8th ), which is coupled to the laser light source, so that laser light ( 6 ' ) of the laser light source ( 5 ) on or in the document body of the security or value document ( 2 ) is positionally controlled, characterized in that the laser light source ( 5 ) is a short pulse laser source that generates laser pulses with a pulse duration of less than 100 ps.

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