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WO2018176090A1 - Procédé de fabrication d'un cylindre configuré pour produire des effets d'image de microstructure - Google Patents

Procédé de fabrication d'un cylindre configuré pour produire des effets d'image de microstructure Download PDF

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Publication number
WO2018176090A1
WO2018176090A1 PCT/AU2018/050285 AU2018050285W WO2018176090A1 WO 2018176090 A1 WO2018176090 A1 WO 2018176090A1 AU 2018050285 W AU2018050285 W AU 2018050285W WO 2018176090 A1 WO2018176090 A1 WO 2018176090A1
Authority
WO
WIPO (PCT)
Prior art keywords
cylinder
relief structures
surface relief
laser
layer
Prior art date
Application number
PCT/AU2018/050285
Other languages
English (en)
Inventor
Karlo Ivan Jolic
Gary Fairless Power
Patrick Swift
Original Assignee
Ccl Secure Pty Ltd
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 Ccl Secure Pty Ltd filed Critical Ccl Secure Pty Ltd
Publication of WO2018176090A1 publication Critical patent/WO2018176090A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/02—Engraving; Heads therefor
    • B41C1/04—Engraving; Heads therefor using heads controlled by an electric information signal
    • B41C1/05—Heat-generating engraving heads, e.g. laser beam, electron beam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/02—Engraving; Heads therefor
    • B41C1/025—Engraving; Heads therefor characterised by means for the liquid etching of substrates for the manufacturing of relief or intaglio printing forms, already provided with resist pattern
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • 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
    • B44—DECORATIVE ARTS
    • B44B—MACHINES, APPARATUS OR TOOLS FOR ARTISTIC WORK, e.g. FOR SCULPTURING, GUILLOCHING, CARVING, BRANDING, INLAYING
    • B44B5/00—Machines or apparatus for embossing decorations or marks, e.g. embossing coins
    • B44B5/02—Dies; Accessories
    • B44B5/026—Dies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B44—DECORATIVE ARTS
    • B44C—PRODUCING DECORATIVE EFFECTS; MOSAICS; TARSIA WORK; PAPERHANGING
    • B44C1/00—Processes, not specifically provided for elsewhere, for producing decorative surface effects
    • B44C1/22—Removing surface-material, e.g. by engraving, by etching
    • B44C1/222—Removing surface-material, e.g. by engraving, by etching using machine-driven mechanical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B44—DECORATIVE ARTS
    • B44C—PRODUCING DECORATIVE EFFECTS; MOSAICS; TARSIA WORK; PAPERHANGING
    • B44C1/00—Processes, not specifically provided for elsewhere, for producing decorative surface effects
    • B44C1/22—Removing surface-material, e.g. by engraving, by etching
    • B44C1/228—Removing surface-material, e.g. by engraving, by etching by laser radiation

Definitions

  • the invention relates generally to cylinders for producing security devices used as an anti-counterfeiting measure in security devices, and in particular to the manufacture of an embossing cylinder.
  • bank notes may have a relief structure, such as a diffraction grating or hologram incorporated into a layer of radiation curable ink.
  • a relief structure such as a diffraction grating or hologram incorporated into a layer of radiation curable ink.
  • One method of incorporating a relief structure into a security document is an embossing process which embosses the desired diffractive relief structure into a radiation curable ink applied to the substrate and irradiating the same whilst the embossing tool is in contact with the radiation curable ink to permanently fix the embossed relief structure.
  • a shim consists of a transfer foil of metallic material bearing the negative of the desired micro-scale or nano-scale diffractive relief structures which is then wrapped around a blank roller.
  • security document includes all types of documents and tokens of value and identification documents including, but not limited to the following: items of currency such as banknotes and coins, credit cards, cheques, passports, identity cards, securities and share certificates, driver's licenses, deeds of title, travel documents such as airline and train tickets, entrance cards and tickets, birth, death and marriage certificates, and academic transcripts.
  • items of currency such as banknotes and coins, credit cards, cheques, passports, identity cards, securities and share certificates, driver's licenses, deeds of title
  • travel documents such as airline and train tickets, entrance cards and tickets, birth, death and marriage certificates, and academic transcripts.
  • the invention is particularly, but not exclusively, applicable to security documents such as banknotes or identification documents such as identity cards or passports formed from a substrate to which one or more layers of printing are applied.
  • security documents such as banknotes or identification documents such as identity cards or passports formed from a substrate to which one or more layers of printing are applied.
  • identification documents such as identity cards or passports formed from a substrate to which one or more layers of printing are applied.
  • the diffraction gratings and optically variable devices described herein may also have application in other products, such as packaging.
  • the term substrate refers to the base material from which the security document or token is formed.
  • the base material may be paper or other fibrous material such as cellulose; a plastic or polymeric material including but not limited to polypropylene (P P), polyethylene (P E ), polycarbonate (P C), polyvinyl chloride (PVC), polyethylene terephthalate (P E T); or a composite material of two or more materials, such as a laminate of paper and at least one plastic material, or of two or more polymeric materials.
  • P P polypropylene
  • P E polyethylene
  • P C polycarbonate
  • PVC polyvinyl chloride
  • P E T polyethylene terephthalate
  • a composite material of two or more materials such as a laminate of paper and at least one plastic material, or of two or more polymeric materials.
  • window refers to a transparent or translucent area in the security document compared to the substantially opaque region to which printing is applied.
  • the window may be fully transparent so that it allows the transmission of light substantially unaffected, or it may be partly transparent or translucent partially allowing the transmission of light but without allowing objects to be seen clearly through the window area.
  • a window area may be formed in a polymeric security document which has at least one layer of transparent polymeric material and one or more opacifying layers applied to at least one side of a transparent polymeric substrate, by omitting least one opacifying layer in the region forming the window area. If opacifying layers are applied to both sides of a transparent substrate a fully transparent window may be formed by omitting the opacifying layers on both sides of the transparent substrate in the window area.
  • a partly transparent or translucent area hereinafter referred to as a "half- window, may be formed in a polymeric security document which has opacifying layers on both sides by omitting the opacifying layers on one side only of the security document in the window area so that the " half-windowjs not fully transparent but allows some light to pass through without allowing objects to be viewed clearly through the half-window.
  • the substrates may be formed from an substantially opaque material, such as paper or fibrous material, with an insert of transparent plastics material inserted into a cut-out, or recess in the paper or fibrous substrate to form a transparent window or a translucent half-window area.
  • Opacifying Layers are substantially opaque materials, such as paper or fibrous material, with an insert of transparent plastics material inserted into a cut-out, or recess in the paper or fibrous substrate to form a transparent window or a translucent half-window area.
  • One or more opacifying layers may be applied to a transparent substrate to increase the opacity of the security document.
  • An opacifying layer is such that LT ⁇ L0 where L0 is the amount of light incident on the document, and LT is the amount of light transmitted through the document.
  • An opacifying layer may comprise any one or more of a variety of opacifying coatings.
  • the opacifying coatings may comprise a pigment, such as titanium dioxide, dispersed within a binder or carrier of heat-activated cross-linkable polymeric material.
  • a substrate of transparent plastic material could be sandwiched between opacifying layers of paper or other partially or substantially opaque material to which indicia may be
  • security device or feature includes any one of a large number of security devices, elements or features intended to protect the security document or token from counterfeiting, copying, alteration or tampering.
  • S ecurity devices or features may be provided in or on the substrate of the security document or in or on one or more layers applied to the base substrate, and may take a wide variety of forms, such as security threads embedded in layers of the security document; security inks such as fluorescent, luminescent and phosphorescent inks, metallic inks, iridescent inks, photochromic, thermochromic, hydrochromic or piezochromic inks; printed and embossed features, including relief structures;
  • interference layers liquid crystal devices; lenses and lenticular structures; optically variable devices (OV Ds) such as diffractive devices including diffraction gratings, holograms and diffractive optical elements (DO E s).
  • OV Ds optically variable devices
  • DOE E s diffractive optical elements
  • the term radiation curable ink used herein refers to any ink, lacquer or other coating which may be applied to the substrate in a printing process, and which can be either be embossed while soft to form a relief structure and cured by radiation to fix the embossed relief structure or applied to a die form, such as a shim, and brought into contact with the substrate before being cured by radiation to fix the " microprinted_ relief structure.
  • the curing process generally (some partial curing can occur earlier and full curing can occur after), takes place when the radiation curable ink and die form (either as an embossing step or microprinting step) is in contact with the substrate.
  • the radiation curable ink is preferably curable by ultraviolet (UV) radiation.
  • the radiation curable ink maybe cured by other forms of radiation, such as electron beams or X-rays.
  • the radiation curable ink is preferably a transparent or translucent ink formed from a clear resin material.
  • S uch a transparent or translucent ink is particularly suitable for printing light-transmissive security elements such as sub-wavelength gratings, transmissive diffractive gratings and lens structures.
  • the transparent or translucent ink preferably comprises an acrylic based UV curable clear embossable lacquer or coating.
  • S uch UV curable lacquers can be obtained from various manufacturers, including Kingfisher Ink Limited, product ultraviolet type UV F-203 or similar.
  • the radiation curable embossable coatings maybe based on other compounds, e.g. nitro-cellulose.
  • the radiation curable inks and lacquers used herein have been found to be particularly suitable for embossing microstructures, including diffractive structures such as diffraction gratings and holograms, and microlenses and lens arrays.
  • the ink is preferably microprinted/embossed and cured by ultraviolet (UV) radiation at substantially the same time.
  • UV ultraviolet
  • the radiation curable ink is applied and embossed at substantially the same time in a G ravure printing process.
  • the radiation curable ink has a viscosity falling substantially in the range from about 20 to about 175 centipoise, and more preferably from about 30 to about 1 50 centipoise.
  • the viscosity may be determined by measuring the time to drain the lacquer from a Zahn C up #2. A sample which drains in 20 seconds has a viscosity of 30 centipoise, and a sample which drains in 63 seconds has a viscosity of 150 centipoise.
  • the intermediate layer preferably comprises a primer layer, and more preferably the primer layer includes a polyethylene imine.
  • the primer layer may also include a cross- linker, for example a multi-functional isocyanate.
  • primers suitable for use in the invention include: hydroxyl terminated polymers; hydroxyl terminated polyester based co-polymers; cross-linked or uncross-linked hydroxylated acrylates; polyurethanes; and UV curing anionic or cationic acrylates.
  • suitable cross-linkers include: isocyanates; polyaziridines; zirconium complexes; aluminium acetyl acetone; melamines; and carbodi-imides.
  • a method for manufacturing a cylinder having surface relief structures configured for producing at least one microstructure image effect in one or more security devices applied to a security document including the following steps: providing a blank cylinder having a surface; and forming surface relief structures corresponding to the at least one microstructure image effect directly on the surface of the cylinder.
  • microstructures with regard to dimensions will vary depending on the particular type of optical effect That is, the dimensions of microstructures that can be formed using the method of the present invention is limited by the minimum feature size that can be achieved using various techniques suitable for manufacturing cylinders having surface relief structures configured for producing microstructure images.
  • the step of forming one or more surface relief structures directly on the surface of the cylinder involves laser ablation.
  • the laser is configured to produce a laser beam width of substantially 5 microns or less.
  • the laser may be configured to produce a laser pulse duration sufficient to vaporise the surface of the cylinder.
  • the laser is configured to produce a laser pulse duration in the range of femtoseconds to nanoseconds. Moreover, selection of a suitable laser will be dependent on the cylinder material to be ablated.
  • a laser beam shaping optical element may be applied in an optical path formed between the laser and the surface of the cylinder in order to achieve the requisite uniformity of the laser beam.
  • the step of forming surface relief structures directly on the surface of the cylinder is carried out by electro-mechanical engraving means using for example, an oscillating stylus formed from a suitable material such as diamond.
  • the electro-mechanical engraving tool may be configured to engrave microstructures of substantially 35 microns or less, or of substantially 5 microns or less.
  • the step of forming surface relief structures directly on the surface of the cylinder is carried out by chemical etching.
  • the step of forming surface relief structures directly on the surface of the cylinder by chemical etching may be preceded by one of the following steps: coating the surface the cylinder with a mask material and laser ablating a pattern of proposed surface relief structures into the mask material to expose the pattern on the surface of the cylinder to thereby form an etching mask; coating the surface of the cylinder with a resist, UV exposing the resist through a film containing a pattern of proposed surface relief structures and developing the UV-exposed resist to expose the pattern on the surface of the cylinder; or coating the surface of the cylinder with a resist, scanning a focussed beam of light onto the resist to expose a pattern of proposed surface relief structures in the resist that is subsequently developed to expose the pattern on the surface of the cylinder.
  • the method for manufacturing a cylinder having surface relief structures configured for producing at least one microstructure image effect in one or more security devices applied to a security document further includes the step of depositing layer of material over the surface relief structures to reduce a size of the microstructure.
  • the step of providing a deposited layer comprises
  • the electroformed layer of material is a metal.
  • the electroformed layer of material may be deposited in a uniform layer.
  • the step of providing a deposited layer comprises chemical vapour deposition of the layer of material.
  • the step of providing a deposited layer comprises depositing a " Diamond-like carbon , (DLC) coating as the layer of material.
  • DLC Diamond-like carbon
  • a computer program product storing instructions for manufacturing a cylinder having surface relief structures configured for producing at least one microstructure image effect in at least one security device applied to a security document, the computer program product storing instructions for controlling a processor to control a device to form surface relief structures corresponding to the at least one
  • a cylinder having surface relief structures configured for producing at least one microstructure image effect in at least one security device applied to a security document, the surface relief structures corresponding to the at least one
  • microstructure image effects being formed directly on a surface of the cylinder.
  • the surface relief structures may comprise mic restructures having dimensions of substantially 35 microns or less, or of substantially 5 microns or less.
  • F igure 1 shows and exemplary apparatus for manufacturing a security document.
  • F igure 2 shows an exemplary microstructure that can be formed on a cylinder by the method of the present invention.
  • F igure 3 shows an exemplary laser ablation system which is used in one embodiment of the present invention.
  • F igure 4 shows an exemplary micro-mechanical engraving system which is used in another embodiment of the present invention.
  • F igure 5 show an optical microscope photograph of an array of micro images of the letter " A_formed by mask ablation according to an embodiment of the present invention.
  • F igures 6A and 6B show an image structure that has been electroplated to reduce the size of the image structure in a post processing step according to one embodiment of the present invention.
  • a radiation curable ink such as a UV curable ink
  • the security element area may take the form of a stripe, a discrete patch in the form of a simple geometric shape, or in the form of a more complex graphical design.
  • the radiation curable ink remains at least partially liquid, it is processed at a processing station 100 including a cylinder 1 10 for embossing the security element structure into the radiation curable ink.
  • the cylindrical surface 120 of the cylinder 1 10 may have a repeating pattern of surface relief formations or the relief structures may be localized to individual shapes corresponding to the shape of the security elements area on the substrate.
  • the radiation curable ink on the substrate is brought into contact with the cylindrical embossing surface 120 of the cylinder 1 10 by a nip roller 130 at the processing station 100, such that the liquid radiation curable ink flows into the surface relief structures of the embossing surface 120.
  • the radiation curable ink is exposed to UV radiation to permanently fix the embossed structures.
  • F ig.1 Whilst F ig.1 is described in relation to a cylinder, it is equally possible to generate such microstructures not through embossing but by application of a radiation curable ink to a cylinder and bringing the cylinder into contact with the substrate to be printed, before being exposed to UV to fix the structures. This process only differs in the method of application of the radiation curable ink, and, potentially, other printing parameters, but the cylinder used is identical regardless of the method of application.
  • the present invention is directed to the manufacture of a cylinder 1 10 suitable for forming microstructure image effects in security devices in security documents.
  • S uch micro-optical effect imagery is at least in part defined by dimension and includes security features such as micro-text lens based optical effects such as image flips, contrast switches, animations, morphing effects, three dimensional floating and/or receding images, moirH magnification effects and combinations thereof.
  • microstructures with regard to dimensions will vary depending on the particular type of optical effect
  • DOE Ds diffractive optically variable devices
  • the smallest dimension of a microstructure is a couple of microns or less. Using current technology, these would be difficult to directly mechanically engrave.
  • the smallest dimensions will depend on the size of the lenses used and the particular optical effect
  • moirH magnification effects employ microstructures having the smallest dimensions.
  • refractive lenses configured to magnify imagery deployed on the other side of a typical polymer substrate, the smallest dimension is around 2 to 10 microns.
  • the actual size is dependent on the complexity of the moirH magnified image, i.e., the more complex the image, the smaller is the minimum feature size within the microstructure.
  • Particular challenges are encountered in forming microstructures of sufficient resolution and integrity in a cylinder to produce high fidelity and high complexity micro-optical effects. These are addressed by the method of the present invention.
  • the microstructure 200 consists of an array of the numeral " 5_ 220 arranged in a hexagonal grid with 55 microns pitch.
  • the numerals 220 are formed by recessing approximately 4 microns deep into the surface 120 of the cylinder 1 10.
  • the smallest feature size of the numerals 220 is the feature width on the cylinder surface 120, at substantially 5 microns.
  • An cylinder 1 10 having such a microstructure 210 formed in its surface by the method of the present invention could be used to create microstructures, for example, moirH effect security features on bank notes that utilise hexagonally packed micro lenses having a similar, but different pitch to that of the correspondingly formed microstructures, e.g. 56 microns pitch lenses could be employed.
  • the cylinderl 10 may be manufactured by forming the microstructures 210 that correspond to the microstructure image effects to be created in one or more security devices by direct laser ablation, chemical etching, mask ablation, or by micro- mechanical engraving means or other suitable techniques.
  • the laser ablation system 300 includes a laser 310, e.g. a picosecond laser, a laser beam 320, an objective lens 330 and a blank cylinder 340.
  • the laser beam 320 width and uniformity is configured to enable homogeneous ablation of the cylinder surface on exposure to the laser beam.
  • optical elements 350 including lenses and/or mirrors and/or beam shapers are placed in the optical pathway between the laser 310 and the cylinder 340 surface.
  • the pulse duration and pulse energy of the laser 310 is controlled so as to vaporise the surface of the cylinder 340 to form a cell.
  • the shape of the cell is defined by the material to be ablated, the intensity profile and pulse duration of the laser beam, the number of applied pulses, and the position of each pulse on the cylinder surface.
  • laser pulse durations are in the femtosecond to nanosecond range, and preferably in the picosecond range.
  • a single laser pulse typically vaporises around 1 micron or less of the material in depth.
  • the cylinders can be formed from a range of materials since the radiation cured process itself causes minimal wear.
  • the blank cylinder may take the form of a hollow steel cylinder that is copper, nickel or zinc plated. Other materials such as chromium or polymers are also envisaged.
  • selection of a suitable laser will be dependent on the cylinder material to be ablated. For example, for materials with high vaporisation temperatures, such as metals, a Q switched YAG laser may be suitable choice. F or example, a Q-switched Nd:YAG multimode laser, with 400W at 1064nm with a repetition rate of 35 KHz. However, for materials requiring a not so high vaporisation temperature, such as polymeric materials, an excimer laser may be a suitable choice.
  • a mask or beam shaping optic 350 such as a diffractive optical element may be used to shape the profile of the cross section of the smallest spot size to optimise the process, for example by facilitating efficient expulsion of materials from the ablated profile.
  • the laser beam 320 can be otherwise controlled, for example, by dynamically controlling the beam width to increase the beam focus where an area of increased depth ablation is required and conversely, to decrease the beam focus where an area of decreased depth ablation is required.
  • the laser ablation process can be configured as a step and repeat process using a mask modulated beam.
  • the laser can be controlled by a suitably designed control system that can write a bitmap file or similar, directly on a blank cylinder, wherein the bitmap file represents a simple O N/O F F laser pulse.
  • the laser is capable of direct writing a greyscale file to the cylinder, wherein each greyscale value corresponds to the ablation depth in the cylinder at the position concerned.
  • the micro images may be at least partially hidden by integrating them into a larger or macro image.
  • portions of a 2D array of micro images, that form part of a moirH magnification device, could be placed in non-image areas within the macro image.
  • the density of the array of micro image elements could be varied, for example, by reducing the number of array elements in the array, to simulate grey levels in the macro image.
  • the microstructures could similarly be formed on a blank cylinder using a direct micro-mechanical engraving system 400 having an oscillating stylus, typically diamond, which cuts cells directly into the surface of the cylinder, assuming that the selected system provides a suitable engraving resolution.
  • a micro-mechanical engraving machine that can achieve high resolution engraving is the Hell E xtreme engraving System having an engraving resolution of substantially 5 microns.
  • Another is the MicroStarTM MicroE ngraving System offered by Daetwyler R &D C orp.
  • the MicroS tarTM system 400 is
  • F igure 4 schematically depicted in F igure 4 and is suitable for engraving a blank cylinder at a resolution of 5 microns and less and could accordingly, be employed to engrave functional micro-optical effect imagery micro structures for lenses on security documents such as bank notes.
  • An appropriately selected cutting tool 420 is controlled via interface 430 which enables importing and uploading of microstructure design files.
  • Alternative methods suitable for manufacturing an cylinder having surface relief structures configured for producing at least one microstructure image effect include chemical etching which involves copying the proposed surface relief structures by direct contact exposing of a photoresist from film to the metal surface of the cylinder. After exposure, developing steps and chemical etching are performed to produce recessed structures in the embossing cylinder which will subsequently contain UV-curable ink for producing the microstructure image effects in security devices. T he exposure step is performed by passing UV light through the film, to expose the underlying resist-coated surface of the cylinder.
  • the resist-coated cylinder surface may be directly exposed with a focused beam of light or laser light, preferably UV light or UV laser light.
  • Mask ablation methods involve coating the cylinder with a mask using immersion or spray coating techniques. The mask is then removed from areas to be chemically etched by thermal ablation, following this the cylinder is chemically etched to produce recessed microstructures.
  • R eferring now to F igure 5 there is shown an optical microscope photograph 500 of an array of micro images of the letter " A_ 510 with a pitch of 50 microns produced using mask ablation followed by chrome plating.
  • T he engraving resolution used was 10,1 60 dots per inch.
  • the engraving artwork was provided in the form of a 10, 160 dpi monochromatic TIF file containing a binary image of the letter " A_ array.
  • microstructures that can be formed using the method of the present invention is limited by the minimum feature size that can be achieved using various techniques suitable for manufacturing cylinders having surface relief structures configured for producing microstructure images. As previously noted such techniques include film contact exposure, focused beam exposure, mask ablation, chemical etching, micro-electromechanical engraving techniques, and direct laser ablation.
  • the minimum feature size will correspondingly impact the minimum image feature size that will be projected by lenses in the case where the microstructure is overlaid with an array of micro lenses. That minimum size is accepted to be substantially 5 microns. However, if the security feature design dictates that smaller microstructures are required to produce the desired image effects, then this may be achieved by electroforming a layer of material, e.g. metal over the surface relief structures in a layer of uniform thickness. [0067] R eferring now to F igures 6A and 6B there is shown schematically how deposition of a layer of material over the microstructure can effectively reduce the size of the surface relief structures. That is, F igure 6A shows the originally formed microstructure having a dimension of 5 microns.
  • F igure 6B shows the same structure 610 after a layer of chrome 620 that is 1 micron thick is electroformed over the surface relief structure. This has the effect of decreasing the dimensions of the microstructure 630 to 3 microns. The decreased dimensions allow a smaller minimum feature size to be achieved.
  • a further advantage of the addition of the chrome layer is that it may assist in extending the lifetime of the cylinder.
  • alternative deposition techniques can be used instead of electroforming, such as chemical vapour deposition (CV D), P lasma Assisted C hemical Vapor Deposition (PACV D) or P hysical Vapour Deposition (PV D).
  • one aspect of the present invention includes the addition of a diamond-like carbon (DLC) coating on the cylinder using appropriate deposition techniques.
  • DLC diamond-like carbon
  • design of suitable mic restructures for coating may entail firstly developing the design so that the portions of the design representing the recessed microstructure have dimensions equal to the target dimensions of the recessed structure after coating. S econdly, the design must be adjusted to compensate for the coating by enlarging the portion of the design representing the recessed area so that its perimeter moves away from the recessed area (i.e. perimeter moves perpendicular to its local tangent), by a predetermined distance, so that the recessed feature area will be increased. If the design is represented as a raster image, this enlargement compensation step could be achieved by applying " Minimum , or " Maximum_filter functions to the image in P hotoshop (depending on whether the recessed areas are represented by black or white pixels). T he " E rode , or " Dilate_ functions known in image processing theory could also be used.
  • a cylinder having integrated surface relief structures configured for producing at least one microstructure image effect can simply be removed from the processing station for cleaning as required, whilst shims are too fragile to endure the shim removal process that is required in order to clean them.
  • problems encountered when using conventional shims, including alignment issues and the presence of joins/seams, are avoided using a cylinder with integral surface relief structures configured for producing at least one microstructure image effect.
  • the angular alignment of the micro imagery to lenses is also improved such that image effects due to lens-to-image skew are reduced, since alignment error due to shim mounting is avoided.
  • This enables larger images implementing multi frame optical effects such as flips, contrast switches, animations and three dimensional designs including interlaced, integral and moirH effects, to be created.
  • the present invention enables the ink to be removed from non-recessed areas.
  • the most common process for achieving this is through the use of a " doctor blade _.
  • the blade is set against the cylinder and used to wipe away ink which is not in recesses on the cylinder. It has not been possible to perform this process using shims _ because the nickel surface is not hard enough to provide sufficient pressure and the shim is not provided on the roller in a way which not cause the doctor blade to catch.
  • shims are usually applied using tape or by welding edges together. This leaves an edge, which is either welded or held by tape which the doctor blade would have to pass over and would cause process issued or would damage the shim.
  • any reference to a cylinder in the description above is, equally, a reference to an embossing cylinder, for embossing of radiation curable ink, or a microprinting cylinder, for microprinting of radiation curable ink, unless otherwise specified.
  • the terms “comprise”, “comprises”, “comprised” or “comprising” are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
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Abstract

L'invention concerne un procédé de fabrication d'un cylindre ayant des structures à relief de surface configuré pour produire au moins un effet d'image de microstructure dans un ou plusieurs dispositifs de sécurité appliqués à un document de sécurité. Le procédé comprend les étapes consistant à fournir un cylindre d'ébauche ayant une surface; et à former des structures à relief de surface correspondant à l'au moins un effet d'image de microstructure directement sur la surface du cylindre.
PCT/AU2018/050285 2017-03-27 2018-03-27 Procédé de fabrication d'un cylindre configuré pour produire des effets d'image de microstructure WO2018176090A1 (fr)

Applications Claiming Priority (2)

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AU2017100354 2017-03-27
AU2017100354A AU2017100354B4 (en) 2017-03-27 2017-03-27 Method for manufacturing an embossing cylinder configured for producing microstructure image effects

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WO2018176090A1 true WO2018176090A1 (fr) 2018-10-04

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AU (1) AU2017100354B4 (fr)
FR (1) FR3064210A1 (fr)
WO (1) WO2018176090A1 (fr)

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EP4177057A1 (fr) * 2021-11-05 2023-05-10 Boegli-Gravures S.A. Procédé de gravure de motifs de code sur la surface de la pièce solide d'outil

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2017100354B4 (en) * 2017-03-27 2017-10-05 Ccl Secure Pty Ltd Method for manufacturing an embossing cylinder configured for producing microstructure image effects

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US20020090578A1 (en) * 1997-12-12 2002-07-11 Mark W. Schaefera Methods for transferring holographic images into metal surfaces
US20080134912A1 (en) * 2003-04-29 2008-06-12 Star-Board Technologies Ltd. Method and Apparatus For Providing Embossed Hidden Images
US20100187806A1 (en) * 2007-06-01 2010-07-29 Giesecke & Devrient Gmbh Endless Material for Security Elements
WO2012019741A1 (fr) * 2010-08-12 2012-02-16 Giesecke & Devrient Gmbh Procédé de fabrication d'outils d'estampage pour des éléments microstructurés à l'aide d'impulsions laser ultra-courtes
AU2017100354A4 (en) * 2017-03-27 2017-05-04 Ccl Secure Pty Ltd Method for manufacturing an embossing cylinder configured for producing microstructure image effects

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020090578A1 (en) * 1997-12-12 2002-07-11 Mark W. Schaefera Methods for transferring holographic images into metal surfaces
US20080134912A1 (en) * 2003-04-29 2008-06-12 Star-Board Technologies Ltd. Method and Apparatus For Providing Embossed Hidden Images
US20100187806A1 (en) * 2007-06-01 2010-07-29 Giesecke & Devrient Gmbh Endless Material for Security Elements
WO2012019741A1 (fr) * 2010-08-12 2012-02-16 Giesecke & Devrient Gmbh Procédé de fabrication d'outils d'estampage pour des éléments microstructurés à l'aide d'impulsions laser ultra-courtes
AU2017100354A4 (en) * 2017-03-27 2017-05-04 Ccl Secure Pty Ltd Method for manufacturing an embossing cylinder configured for producing microstructure image effects

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4177057A1 (fr) * 2021-11-05 2023-05-10 Boegli-Gravures S.A. Procédé de gravure de motifs de code sur la surface de la pièce solide d'outil
WO2023079418A1 (fr) * 2021-11-05 2023-05-11 Boegli-Gravures Sa Procédé de gravure de motifs de code dans une surface d'outil d'une pièce solide

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AU2017100354B4 (en) 2017-10-05
AU2017100354A4 (en) 2017-05-04
FR3064210A1 (fr) 2018-09-28

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