WO2008029128A2 - Dispositif de sécurité fondé sur un dispositif de microprisme individualisé - Google Patents

Dispositif de sécurité fondé sur un dispositif de microprisme individualisé Download PDF

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Publication number
WO2008029128A2
WO2008029128A2 PCT/GB2007/003342 GB2007003342W WO2008029128A2 WO 2008029128 A2 WO2008029128 A2 WO 2008029128A2 GB 2007003342 W GB2007003342 W GB 2007003342W WO 2008029128 A2 WO2008029128 A2 WO 2008029128A2
Authority
WO
WIPO (PCT)
Prior art keywords
security
prismatic
image
document
security device
Prior art date
Application number
PCT/GB2007/003342
Other languages
English (en)
Other versions
WO2008029128A3 (fr
Inventor
Lawrence George Commander
Christopher John Eastell
Roland Isherwood
Original Assignee
De La Rue International Limited
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 De La Rue International Limited filed Critical De La Rue International Limited
Publication of WO2008029128A2 publication Critical patent/WO2008029128A2/fr
Publication of WO2008029128A3 publication Critical patent/WO2008029128A3/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/14—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of indefinite length
    • B29C39/148—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of indefinite length characterised by the shape of the surface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/26—Control of fuel supply
    • F02C9/42—Control of fuel supply specially adapted for the control of two or more plants simultaneously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • B29D11/00278—Lenticular sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
    • B42D25/29—Securities; Bank notes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type
    • G02B5/124—Reflex reflectors cube corner, trihedral or triple reflector type plural reflecting elements forming part of a unitary plate or sheet
    • B42D2033/04—
    • B42D2035/20—
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/04—Prisms
    • G02B5/045—Prism arrays

Definitions

  • the present invention relates to improvements in security devices that can be used in varying shapes and sizes for various authenticating or security applications, particularly a device comprising a prismatic film customised to display identifying information.
  • Security documents such as banknotes now frequently carry optically variable devices such as diffraction gratings or holographic optical microstructures as a security feature against copy and counterfeit. This has been motivated by the progress in the fields of computer-based desktop publishing and scanning, which renders conventional security print technologies such as intaglio and offset printing more prone to attempts to replicate or mimic. Examples of such holographic structures and their manufacturing techniques can be found in EP0548142 and EP0632767 filed in the name of De La Rue Holographies Ltd.
  • a significant portion of the incident light striking the smooth surface at an angle Q 2 to the normal of the smooth surface which produces refracted light that strikes the structured surface, for example at point c, at an angle, ⁇ i, less than the critical angle will be transmitted through the prismatic film (ray 2) and the remainder of the incident light will be reflected by the smooth surface.
  • the switch angle, ⁇ spd , for the prisms-down configuration is the smallest angle of incidence with respect to the normal of the smooth surface at which the incident light is not totally internally reflected within the prism structure.
  • the prismatic material In order for the device in WO03055692 and WO04062938 to function the prismatic material must have a significantly higher refractive index than the neighbouring material typically the adhesive used to adhere it to the document.
  • a refractive index difference of at least 0.6 between the prismatic material and the adhesive is required for a device comprising an array of linear prisms as shown in the prior art.
  • Polymeric adhesives/coatings typically have a refractive index of no less than 1.4 and therefore in order to achieve a difference of at least 0.6 the refractive index of the prismatic material must be at least 2.
  • Prismatic films are typically made from UV curable polymers or thermoplastic polymeric films which have refractive indices in the range 1.4- 1.6. It is very difficult and expensive to increase the refractive index of a polymeric material above 1.7, and therefore the cited prior art does not provide a practical solution.
  • the devices described in the cited prior art contain only a simple on- off switch, i.e. the regions containing the prismatic structures switch from totally reflecting to transparent at the same specified angle, which limits the extent to which they can be customised.
  • This limitation provides an advantage to the counterfeiter who only requires to produce one generic prismatic film that can be used to counterfeit a whole range of security devices.
  • JP-A-2004-262144 describes another example of a prismatic film being used as a security device.
  • the trough portions of the prisms are partially filled with a colouring resin to form patterns.
  • the adhesive is provided on the film in a pattern instead of the colouring resin.
  • the prismatic surface structure may be provided directly in a surface of the transparent substrate or in a further layer, such as a film, attached to the substrate.
  • FIGS. 17a and 17b illustrate, in plan, two further examples of security devices according to the invention.
  • Figures 27a and 27b illustrate the appearance of security device based on the Figure 3 construction, applied over a printed image, when viewed normally and off-axis respectively;
  • Figures 39a and 39b illustrate the incorporation of a security device into a transparent area of a security document
  • the polar plot in Figure 9 shows that the angular range for the truncated structure in which TIR occurs is significantly greater than the angular range for the non-truncated structure ( Figure 7).
  • TIR occurs for angles of incidence between 10-20° away from the normal when viewed perpendicularly to the long axes of the linear prisms (along arc 2)
  • micro-embossing An alternative process for the production of films comprising a surface prismatic structure is micro-embossing. Suitable micro-embossing processes are described in US4601861 and US6200399. In US4601861 a method is described for continuously embossing a corner-cube structure in a sheeting of thermoplastic material, where the actual embossing process takes place at a temperature above the glass transition temperature of the sheeting material.
  • the device will not exhibit TIR in the perimeter regions where the adhesive contacts the prism film because of the insufficient difference in the refractive index between the adhesive and the prismatic structure, but TIR will be exhibited in the central region because of the higher refractive index difference observed at the air/prism interface.
  • the prismatic array 13 consists of an array of parallel linear prisms with a prism pitch of 20 ⁇ m and a prism height of 10 ⁇ m.
  • the difference in refractive index between the adhesive and the materials forming the prismatic structure should be no greater than 0.2, and preferably no greater than 0.05 and even more preferably no greater than 0.02.
  • negative designs are created within the perimeter adhesive layer, i.e. the adhesive is omitted in certain regions.
  • the adhesive is omitted in certain regions.
  • the negative images in the adhesive layer will be totally reflecting and appear "metallic" against the transparent background of the adhesive layer.
  • the prismatic film is not totally reflecting the negative images in the perimeter adhesive layer switch from totally reflecting to transparent and are indistinguishable from the rest of the perimeter layer.
  • Figure 16 illustrates an example where images are created within the perimeter adhesive layer.
  • the device is constructed as shown in Figure 3a, except that in the corner regions of the device adhesive is omitted in localised regions 200 within the perimeter adhesive layer 202 to define the numeral "50".
  • the prismatic film comprises at least two regions which form a prism/air interface where the refractive index of the at least two regions are different.
  • the difference in refractive index of the two prismatic regions enables the generation of an optically variable security device based on a prismatic film where different regions of the film exhibit a different optically variable effect.
  • the coated film is then held in intimate contact with the production tool 65 in the form of an embossing cylinder, whereby the prismatic structure 66 defined on the production tool is replicated in both resins 1 and 2 held on the substrate film (Step 3).
  • UV light is used at the point of contact to cure and harden the resin, and as a final stage, the flexible prismatic film is released from the embossing cylinder (Step 4).
  • the process takes place as a reel-to-reel process.
  • FIG 26 illustrates an alternative embodiment of the present invention where a thin buffer layer 78 is provided between the release layer 71 and the carrier film 70.
  • the buffer layer 78 provides a layer into which the cut can penetrate such that the tolerance of the die-cutting process can be increased without the risk of cutting into the carrier film.
  • the buffer layer 78 may take the form of a tie-coat polymeric coating or a thin polymeric film.
  • the thickness of the buffer layer is preferably in the range 1-20 ⁇ m and even more preferably in the range 2-12 ⁇ m.
  • FIG. 30 illustrates one example where a security device 230 having the construction shown in Figure 3a is applied over a printed image 232 such that when it is totally reflecting the prismatic film substantially conceals part of the printed image.
  • a security device 230 having the construction shown in Figure 3a is applied over a printed image 232 such that when it is totally reflecting the prismatic film substantially conceals part of the printed image.
  • an image 232 of a bird is printed onto the document using lithographic printing.
  • the security device 230 comprising a prismatic film 2 is then applied over the printed image using a perimeter adhesive layer 3, such that in its totally reflecting state, when viewed at normal incidence, the central region of the device substantially conceals the bird's eye (Figure 30A).
  • Figure 30B On tilting the device ( Figure 30B) and viewing away from normal incidence the central region switches from totally reflecting to transparent and the bird's eye is revealed and the full printed image is completed.
  • Figure 31 shows a further example where the switching image is located within a conventional printed image.
  • the printed image 240 comprises an arrangement of geometrical shapes.
  • the security device comprising the prismatic film has the construction shown in Figure 3a.
  • Figure 31a illustrates the device in plan view showing the position of the perimeter adhesive layer 3 and the triangular adhesive-free region 242.
  • the device is the applied over the printed image such that when viewed at normal incidence the "metallic" triangle locates within the printed structure to form a first image (Figure 31b).
  • the prismatic film On tilting the security document away from normal incidence the prismatic film becomes substantially transparent and the printed artwork under the "metallic" triangle is revealed forming a second image ( Figure 31c) which is complementary in design and content to the first image.
  • the prismatic structure is a series of parallel linear prisms with planar facets arranged to form a grooved surface
  • visible moire patterns can be generated by a combination of the repeating pattern of the linear grooves with an array of fine lines underneath the security device.
  • the moire pattern will be observed when the prism film in not totally reflecting. This provides an additional security feature over the metallic to transparent switch, in that when the device switches to its transparent state a dynamic moire image is observed.
  • the use of the air gap in the current invention enhances the observed moire effect by increasing the spacing between the linear grooves and the printed line array. The enhancement is observed as an increase in the apparent movement of the observed moire image.
  • functional inks we mean inks that react to an external stimulus.
  • Inks of this type include but are not limited to fluorescent, phosphorescent, infrared absorbing, thermochromic, photochromic, magnetic, electrochromic, conductive and piezochromic.
  • the security device is embossed with a non-diffractive line structure.
  • Non-diffractive line structures are structures which produce an optically variable effect when the angle of incidence light varies, but in which this effect is not caused by interference or diffraction.
  • Security devices based on non- diffractive line structures are known in the prior art for example WO9002658 describes a security device in which one or more transitory images are embossed into a reflective surface.
  • WO9820382 discloses a further security device in which a group of elemental areas in which lines extend at different angles from each other form respective image pixels.
  • US1996539 discloses a decorative device in which a relief structure is formed in a surface and has an optically variable effect.
  • WO2005080089 discloses a security device which has segments defined by line structures in a reflective portion of a substrate, which cause incident light to be reflected non-diffractively as the angle of incidence changes.
  • the device is only totally reflecting in the region where it is exposed on both sides, the rest of the device is in intimate contact with the fibres forming the document and therefore in this region a prism/air interface is no longer maintained.
  • the fact that the transparent to "metallic" switch is inverted by viewing from the opposite side of the document enables the document to be easily authenticated by placing the transparent area on a printed image/document. When viewed normally from one side of the document the image will be visible through the transparent aperture, but when the banknote is turned over the image will be concealed by an apparently reflective "metallic" film.
  • an identifying image can be incorporated into the prismatic film either by using localised regions of adhesive or by locally varying the refractive index of the prismatic film.
  • Figure 48 illustrates a secure document, for example a banknote, containing one example of the optically variable effect that could be generated from the security device in Figure 47.
  • Prismatic array 3 is replicated onto the clear polymeric film in the form of a star and prismatic array 4 is replicated over the active area not covered by prismatic array 3 such that it forms the background area.
  • Prismatic arrays 3 and 4 comprise a series of parallel linear prisms and are replicated such that the long axes of the linear prisms forming the star (prismatic array 3) are substantially perpendicular to the long axes of the prisms forming the background area (prismatic array 4).
  • the lines in Figure 48 schematically represent the long axes of the linear prisms.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Accounting & Taxation (AREA)
  • Finance (AREA)
  • Business, Economics & Management (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ophthalmology & Optometry (AREA)
  • Credit Cards Or The Like (AREA)
  • Burglar Alarm Systems (AREA)

Abstract

La présente invention concerne un dispositif de sécurité comprenant un substrat transparent (1) pourvu d'une structure de surface prismatique (2) qui définit un réseau de facettes sensiblement planes. Une couche d'adhésif (3) s'étend autour du périmètre d'une surface du substrat (1) de sorte que ce dispositif de sécurité puisse être collé à un autre substrat, au moins quelques parties de cette surface étant exposées à l'air, ces parties étant espacées de l'autre substrat en utilisation afin de définir un substrat transparent et/ou une interface air de sorte que les parties correspondant à la structure de surface prismatique (2) forment un réflecteur du fait de la réflexion interne totale lorsqu'elles sont vues selon au moins un premier angle de vision et sont transparentes lorsqu'elles sont visionnées selon au moins un second angle de vue.
PCT/GB2007/003342 2006-09-08 2007-09-05 Dispositif de sécurité fondé sur un dispositif de microprisme individualisé WO2008029128A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0617729.9 2006-09-08
GBGB0617729.9A GB0617729D0 (en) 2006-09-08 2006-09-08 Security device based on customised microprism device

Publications (2)

Publication Number Publication Date
WO2008029128A2 true WO2008029128A2 (fr) 2008-03-13
WO2008029128A3 WO2008029128A3 (fr) 2008-06-26

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GB (1) GB0617729D0 (fr)
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010091888A1 (fr) * 2009-02-14 2010-08-19 Luxexcel Holding Bv Dispositif d'orientation de faisceaux lumineux, dispositif d'illustration et procede de production de ces dispositifs d'orientation et d'illustration
WO2012120305A1 (fr) * 2011-03-08 2012-09-13 Ian Eastwood Élément de sécurité pour documents
WO2013190048A1 (fr) * 2012-06-20 2013-12-27 Leonhard Kurz Stiftung & Co. Kg Procédé de transfert d'une partie décorative d'un film d'estampage
WO2014099486A1 (fr) * 2012-12-21 2014-06-26 3M Innovative Properties Company Articles rétro-réfléchissants et photoluminescents
WO2014096167A1 (fr) * 2012-12-20 2014-06-26 Bundesdruckerei Gmbh Caractéristique de sécurité pour un produit de valeur et/ou de sécurité, le produit de valeur et/ou de sécurité présentant la caractéristique de sécurité et procédé de production de la caractéristique de sécurité
US8840235B2 (en) 2010-06-07 2014-09-23 Luxexcel Holding Bv. Print head, upgrade kit for a conventional inkjet printer, inkjet printer and method for printing optical structures
US9592690B2 (en) 2011-01-06 2017-03-14 Luxexcel Holding B.V. Print head, upgrade kit for a conventional inkjet printer, printer and method for printing optical structures
EP2996886B1 (fr) 2013-05-17 2017-07-05 De La Rue International Limited Documents de sécurité et procédés de fabrication
US9902186B2 (en) 2012-07-06 2018-02-27 De La Rue International Limited Security devices

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5591527A (en) * 1994-11-02 1997-01-07 Minnesota Mining And Manufacturing Company Optical security articles and methods for making same
US5643400A (en) * 1995-05-19 1997-07-01 Reflexite Corporation Method and apparatus for producing seamless retroreflective sheeting
JP2004262144A (ja) * 2003-03-03 2004-09-24 Dainippon Printing Co Ltd 真偽判定体と真偽判定体用ラベル
WO2006095161A2 (fr) * 2005-03-10 2006-09-14 De La Rue International Limited Dispositif de securite fonde sur un film a microprisme personnalise

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5591527A (en) * 1994-11-02 1997-01-07 Minnesota Mining And Manufacturing Company Optical security articles and methods for making same
US5643400A (en) * 1995-05-19 1997-07-01 Reflexite Corporation Method and apparatus for producing seamless retroreflective sheeting
JP2004262144A (ja) * 2003-03-03 2004-09-24 Dainippon Printing Co Ltd 真偽判定体と真偽判定体用ラベル
WO2006095161A2 (fr) * 2005-03-10 2006-09-14 De La Rue International Limited Dispositif de securite fonde sur un film a microprisme personnalise

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010091888A1 (fr) * 2009-02-14 2010-08-19 Luxexcel Holding Bv Dispositif d'orientation de faisceaux lumineux, dispositif d'illustration et procede de production de ces dispositifs d'orientation et d'illustration
US10365413B2 (en) 2009-02-14 2019-07-30 Luxexcel Holding B.V. Device for directing light beams, illustration device, method for producing a device and an illustration device
US8840235B2 (en) 2010-06-07 2014-09-23 Luxexcel Holding Bv. Print head, upgrade kit for a conventional inkjet printer, inkjet printer and method for printing optical structures
US9592690B2 (en) 2011-01-06 2017-03-14 Luxexcel Holding B.V. Print head, upgrade kit for a conventional inkjet printer, printer and method for printing optical structures
WO2012120305A1 (fr) * 2011-03-08 2012-09-13 Ian Eastwood Élément de sécurité pour documents
WO2013190048A1 (fr) * 2012-06-20 2013-12-27 Leonhard Kurz Stiftung & Co. Kg Procédé de transfert d'une partie décorative d'un film d'estampage
CN104520119B (zh) * 2012-06-20 2018-09-21 雷恩哈德库兹基金两合公司 用于转移压印膜的装饰部段的方法
CN104520119A (zh) * 2012-06-20 2015-04-15 雷恩哈德库兹基金两合公司 用于转移压印膜的装饰部段的方法
US9902186B2 (en) 2012-07-06 2018-02-27 De La Rue International Limited Security devices
US10543710B2 (en) 2012-07-06 2020-01-28 De La Rue International Limited Security devices
WO2014096167A1 (fr) * 2012-12-20 2014-06-26 Bundesdruckerei Gmbh Caractéristique de sécurité pour un produit de valeur et/ou de sécurité, le produit de valeur et/ou de sécurité présentant la caractéristique de sécurité et procédé de production de la caractéristique de sécurité
WO2014099486A1 (fr) * 2012-12-21 2014-06-26 3M Innovative Properties Company Articles rétro-réfléchissants et photoluminescents
EP2996886B1 (fr) 2013-05-17 2017-07-05 De La Rue International Limited Documents de sécurité et procédés de fabrication

Also Published As

Publication number Publication date
WO2008029128A3 (fr) 2008-06-26
GB0617729D0 (en) 2006-10-18

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