• 专利附录
  • 专利说明
  • 权利要求
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    • 专利摘要:
    An optical device comprising an at least substantially transparent substrate having a first side comprising a source layer having an array of source elements, and a second side comprising an optically variable device (OVD) layer having a corresponding array of diffractive elements, each one Source element is configured to provide an integrated light source for an associated diffraction element in the illumination of the first side, and wherein the diffractive elements are configured to produce an optical effect that is observable when the diffractive elements are viewed by a viewer, such as for example, to the naked eye when illuminated by the swelling elements.
    公开号:AT519066A2
    申请号:T9191/2016
    申请日:2016-05-20
    公开日:2018-03-15
    发明作者:
    申请人:Ccl Secure Pty Ltd；
    IPC主号:
    专利说明:

    The invention relates generally to the field of optical
    Devices, in particular those used to improve the security against forgery of documents.
    BACKGROUND OF THE INVENTION
    Optically variable devices such as holograms, diffractive optical elements, microlens devices, interference pigment devices, etc. are known to improve the security against falsification of documents. Typically, the optically variable device is molded or attached to the document and provides protection against conventional copying techniques, such as photocopying, since such techniques are unable to accurately reproduce the variable appearance of the device.
    In response to counterfeiting improvements in reproduction, optically variable devices that are more difficult to counterfeit have been developed using advanced techniques or at least satisfactory mimicking existing optically variable devices.
    In order for an optically variable device to be useful in providing protection, users of documents to which the device is attached should be able to easily identify the device and the optical effect it provides. Typically include desirable properties of optically variable ones
    Devices brightness, memorability,
    Ease of use etc.
    2/38 • · · · ·· · · · · · ·· ····· ·· · · · • · · · · · · · ·· · ······ · · ··· ·· ···· ··· · ·· ·· ·· ··· ·· ··
    Improvements of such devices are therefore necessary in order to continuously increase the deterrence of counterfeits.
    SUMMARY OF THE INVENTION
    Existing diffractive devices, such as diffractive optical elements (DOE), produce optically variable effects through diffractive interaction with incident light. The optically variable effect often strongly depends on the nature of the incident light source, for example whether it is a diffuse light, a point light source, and the shape of the light source.
    In view of this, an optical device is provided according to one aspect of the present invention, comprising an at least substantially transparent substrate with a first side, comprising a swelling layer with an arrangement of swelling elements, and a second side, comprising a layer of an optically variable device (OVD ) with a corresponding arrangement of diffractive elements, wherein each source element is configured to provide an integrated light source when illuminating the first side by an external light source, which is a light source that provides light for an associated diffraction element essentially independently of the external light source , and wherein the diffractive elements are configured to produce an optical effect that is observable when the diffractive elements are viewed by an observer, such as the naked eye when illuminated by the source elements, wherein each
    3/38
    Diffraction element according to the shape of its associated
    Source element is configured.
    Preferably one or both of: a) the source elements define images that are varied or fixed between the source elements; and b) the surface relief of the diffractive elements between the diffractive elements is varied so that it appears that the observed image or images change the magnification; move; change the shape; change the brightness; change the contrast; and / or change the hue when the viewing angle is changed.
    Each source element can define a source image and each diffractive element can define a diffractive focusing element, preferably a diffractive element with a circular or cylindrical zone plate, configured to provide an enlarged and / or shifted projection of the source image of the associated source element.
    Typically, the substrate comprises a characteristic thickness, and the surface relief of each diffractive element is determined in part by the characteristic thickness.
    Each diffractive element is preferably clearly assigned to a source element.
    Each source element preferably has at least one linear dimension that is less than a space between
    4/38 the source element and its associated diffractive element, preferably approximately half the space.
    According to another aspect of the present invention, there is provided a document, preferably a security document, that includes the optical device of the previous embodiment.
    The document preferably comprises a transparent one
    Document substrate, a region of which is the same
    The substrate corresponds to the optical device, the document preferably also comprising opacifying layers on each side of the document substrate, each not present in overlapping regions, thereby defining a window in which the optical device is located. Alternatively, the optical device can be separately molded onto the document and attached to the document in a window region, the window either being a transparent portion of the document or corresponding to a distal portion of the document.
    According to a further aspect of the present invention, there is provided a method for manufacturing the optical device of the first aspect, comprising the following steps: producing an underlay component in an inverted profile on a required OVD layer profile; Determining a print pattern that corresponds to a required swelling layer; Applying radiation curable ink to a surface of a transparent substrate;
    Emboss the radiation-curable ink with the
    Underlay component, and curing the radiation curable ink, thereby forming the diffraction layer; and
    5/38
    Printing the print pattern on an opposite surface of the substrate, preferably congruent with the surface profile of the diffraction layer.
    The embossing step and the pressing step are preferably performed substantially simultaneously.
    Optionally, the transparent substrate includes opacifying layers located on each surface, the opacifying layers not being present in the region of the radiation-curable ink, thereby defining a window that encompasses the optical device.
    Security document or token
    The term closes in the sense used here
    Security documents and tokens include all types of documents and tokens of value and identification documents, including the following: Currency elements such as banknotes and coins, credit cards, passports, ID cards, securities and share certificates, driver's licenses, title deeds, travel documents such as flight and train tickets, Tickets and tickets, birth, death and marriage certificates and academic transcripts.
    The invention is particularly, but not exclusively, applicable to security documents or tokens such as banknotes or identification documents such as ID cards or passports that are formed from a substrate to which one or more printing layers are applied. The diffraction gratings and optically variable devices described here can also be used in other products such as packaging.
    6/38
    Security device or feature
    As used herein, the term includes
    Security device or feature Any of a large number of security devices, elements or features which are intended to protect the security document or token from forgery, copying, modification or falsification.
    Security devices or features can 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 can take a wide variety of forms, such as security threads embedded in layers of the security document are;
    Security inks such as fluorescent, luminescent and phosphorescent inks, metallic inks, iridescent inks, photochromic, thermochromic, hydrochromic or piezochrome inks; printed and embossed features, including relief structures; Interference layers;
    Liquid crystal devices; Lenses and lenticular structures; optically variable devices (OVD) such as diffractive devices, including diffraction gratings, holograms and diffractive optical elements (DOE).
    substratum
    In the sense used here, the term substrate refers to the starting material from which the security document or token is formed. The starting material can be paper or another fiber material such as cellulose, a plastic or a polymer material, including, among others, polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate (PET), biaxially oriented polypropylene ( BOPP); or a composite of two or
    7/38 more materials, such as a laminate of paper and at least one plastic material or of two or more polymer materials.
    Transparent windows and half windows
    In the sense used here, the term window refers to a transparent or translucent area in the security document in comparison to the essentially opaque region to which a print is applied. The window can be completely transparent so that it allows the transmission of light to be substantially unaffected, or it can be partially transparent or translucent, allowing the transmission of light in part without allowing objects to be clearly seen through the window area are.
    A window area can be formed in a polymeric security document that has at least one layer of transparent polymeric material and one or more opaque layers that are applied to at least one side of a transparent polymeric substrate by omitting at least one opaque layer in the region that forms the window area. If covering layers are applied to both sides of a transparent substrate, a completely transparent window can be formed by omitting the covering layers on both sides of the transparent substrate in the window area.
    A partially transparent or translucent area, hereinafter referred to as a “half window,” can be formed in a polymeric security document, the opaque one
    8/38 • · · · · · ···· · · ····· ·· ··· • ·· · · ·· · ·· · • ·· ·· · · ···· ·· ···· ··· · ·· · · · · · · · ·· ··
    Has layers on both sides by omitting the opaque layers on only one side of the security document in the window area so that the "half-window is not completely transparent, but does allow some of the light to pass through without allowing objects are clearly visible through the half window.
    Alternatively, it is possible for the substrates to be formed from an essentially opaque material such as paper or fiber material, an insert made of transparent plastic material being inserted into a cutout or a cutout in the paper or fiber substrate in order to provide a transparent window or translucent material Train half-window area.
    Opaque layers
    One or more opaque layers can be applied to a transparent substrate to increase the opacity of the security document. An opaque layer is such that L T <Lo, where Lo is the amount of light that is incident on the document and L T is the amount of light that is transmitted through the document. A covering layer can comprise any one or more of a variety of covering coatings. For example, the opaque coatings can comprise a pigment, such as titanium dioxide, which is incorporated in one
    Binder or a carrier substance of a heat-activated crosslinkable polymer material is dispersed. Alternatively, a substrate made of transparent plastic material could be arranged between opaque layers of paper or another partially or essentially opaque material
    9/38, on which information can be subsequently printed or otherwise applied.
    Refractive index n
    The refractive index of a medium n is the ratio of the speed of light in a vacuum to the speed of light in the medium. The refractive index n 2 of a lens determines the amount in which light rays that reach the lens surface are refracted, according to Snellius' law of refraction:
    ni.sinCöi) = n 2 .sin (0 2 ) where the angle between an incident beam and the normal beam at the point of incidence is at the lens surface, 0 2 the angle between the refracted beam and the normal beam at the point of incidence is, and Πγ the
    Refractive index of air is (as an approximation can be taken for a value of 1).
    Embossable radiation curable ink
    The term embossable radiation curable ink used here refers to any ink, varnish or other coating which can be applied to the substrate in a printing process and which can be embossed while it is being used it is soft to a
    Form relief structure, and can be hardened to fix the embossed relief structure. The curing process does not take place until the radiation-curable ink is embossed
    10/38
    • · • · ·· • · «·· ·· • · • · • ·· • • « • · • · • · · • • • · • · • · • * • • • · · •
    however, it is possible that the hardening process may occur either after the stamping or at substantially the same time as the stamping step. The radiation-curable ink is preferably curable by ultraviolet (UV) radiation. Alternatively, the radiation-curable ink can be 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. Such a transparent or translucent ink is particularly suitable for printing translucent security elements such as
    Sub-wavelength gratings, transmissive diffractive gratings and lens structures are suitable.
    In a particularly preferred embodiment, the transparent or translucent ink preferably comprises a UV-curable, clear, embossable, acrylic-based lacquer or such a coating.
    Such UV curable varnishes can be obtained from various manufacturers, including Kingfisher Ink Limited, product Ultraviolet Type UVF-203 or the like. Alternatively, the radiation-curable embossable coatings can be applied to other compounds, e.g. B. nitrocellulose based.
    It has been found that the radiation-curable inks and lacquers used here are particularly suitable for embossing microstructures, including diffractive structures such as diffraction gratings and holograms and microlenses and lens arrays. However, they can also be used with larger ones
    11/38 * · Φ · «· w ··» · ·· * ···· ·· er «•« · · ··· · · · · • · · · «· · · ··· * ·· ♦ «· ·« · · »* ·· ·· ··· ··« w
    Relief structures, such as non-diffractive optically variable devices.
    The ink is preferably embossed and cured by ultraviolet (UV) radiation at substantially the same time. In a particularly preferred embodiment, the radiation-curable ink is applied and embossed at substantially the same time in a gravure printing process.
    Preferably, in order to be suitable for gravure printing, the radiation curable ink has a viscosity that is substantially in the range from about 20 to about 175 centipoise, more preferably from about 30 to about 150 centipoise. The viscosity can be determined by measuring the time for the paint to drain from a No. 2 Zahn cup. A sample that is drained in 20 seconds has a viscosity of 30 centipoise and a sample that is drained in 63 seconds has a viscosity of 150 centipoise.
    For some polymer substrates, it may be necessary to apply an intermediate layer to the substrate before the radiation curable ink is applied to improve the adhesion of the embossed structure which is formed on the substrate using the ink. The intermediate layer preferably comprises an undercoat layer, and more preferably the undercoat layer includes a polyethyleneimine. The undercoat layer may also include a crosslinking agent, for example a multifunctional isocyanate.
    Examples of other primers suitable for use in the invention include: hydroxyl-terminated polymers; hydroxyl-terminated copolymers
    12/38 polyester-based; crosslinked or uncrosslinked hydroxylated acrylates; polyurethanes; and UV curing anionic or cationic acrylates. Examples of suitable ones
    Crosslinking agents include: isocyanates; polyaziridines; zirconium; aluminum acetylacetone; Melamine; and carbodiimides.
    Metallic nanoparticle ink
    As used herein, the term metallic nanoparticle ink refers to metallic particle ink with an average size of less than one micron.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Embodiments of the invention will now be described with reference to the accompanying drawings. It is to be understood that the embodiments are presented for illustration only and the invention is presented by them
    Illustration is not restricted. For the
    Drawings' applies:
    Figures la and lb show documents with optical
    Devices according to various embodiments of the invention;
    FIG. 2 shows a simplified illustration of an optical device according to the present invention;
    FIG. 3 shows a swelling layer and an OVD layer according to one embodiment;
    13/38
    Figure 4 shows the interaction between a light source, a lattice structure and an eye;
    Figure 5 shows a source element configured as a slit and a corresponding grating of a diffraction element;
    Figure 6 shows an external light source illuminating a source element and a diffraction element configured to provide an enlarged equivalent to the image of the source element; and
    Figure 7 shows a method of manufacturing an optical device.
    DESCRIPTION OF PREFERRED EMBODIMENT
    Figures la and lb each show a document 2 with an optical device 4 according to embodiments of the invention. Optical device 4 includes a transparent (or at least substantially transparent) substrate 8. Document 2 also includes a substrate (herein
    Document substrate 9). In the embodiment from FIG. 1 a, the two substrates 8, 9 are the same, that is to say that the optical device 4 and the document 2 share the same substrate 8, 9. In the embodiment from FIG. 1b, the document substrate 9 differs from the substrate 8 of the optical device 4.
    In any case, document 2 contains first and second opacifying layers 7a, 7b. The opacifying layers 7a, 7b
    14/38 act to reduce or eliminate the transparency of document 2 in the regions in which the layers 7a, 7b are present. In the embodiments shown, both opacifying layers 7a, 7b are not present in the area of the optical device 4, which causes the optical device 4 to be located within one
    Window region of document 2 is located.
    It is also possible that the document 2 is inherently opaque (or substantially opaque), for example where the document substrate 9 is paper or a paper composite. In this case, the opacifying layers 7a, 7b are not necessarily required. In this case, the optical device 4 is still located in a window region of the document 2, which can be achieved using known methods, such as shaping the optical device 4 as a film and applying the film to a cut-out area of the opaque document substrate 9.
    The optical device 4 typically provides one
    Security function ready, that is to say that the optical device 4 acts to reduce the susceptibility of the document 2 to forgery. The optical device 4 can be referred to as a "security device or a" security token when used for this purpose. A document 2 that requires protection against counterfeiting is often referred to as a “security document.
    Figures la and lb also show others
    Security features 6 (6a in FIG. 1a, 6b in FIG. 1b), which reduce the susceptibility of the document 2 for forgery in combination with the optical device 4
    15/38
    can support. Figure la shows the rest
    Security feature 6a is implemented in a window region of document 2, the additional security feature 6b being implemented in FIG. 1b in an opaque (i.e. non-windowed) region of document 2. The illustrated arrangements are merely examples and, in general, document 2 may include one or more security features 6, each implemented in a window, half window, or opaque region of document 2. Exemplary others
    Security features 6 include: optically variable
    Devices, such as diffractive optical elements,
    Kinograms®, microlens-based features, holograms, etc .; Watermark images, small print, etc.
    As shown in FIGS. 1 a and 1 b and in more detail in FIG. 2, the optical device 4 generally includes a substrate 8 with a swelling layer 10 on a first side 16 a and an OVD layer 12 opposite the swelling layer 10 on a second side.
    Figure 3 shows the source layer 10 and the OVD layer 12 in more detail. The source layer 10 comprises an arrangement of source elements 18. The source elements 18 typically correspond to a pixelated printed source pattern, that is to say that they are produced by selective printing on regions of the source layer 10 and each source element 18 represents a “pixel of the source pattern. The arrangement can be as shown; that is, a rectangular square matrix. According to one implementation, the arrangement is selected such that the source elements 18 are arranged in any repetitive manner, for example by arrangement according to one of the five two-dimensional Bravais grids. In a
    16/38
    alternative implementation, the arrangement of the source elements 10 need not be repeated.
    Each source element 18 of the source layer 10 defines an image, which is defined by a transparent section and an opaque section. Typically, the opaque section defines at least one border of the image so that the entire transparent section of the source element 10 is within the border. The source elements 10 are typically created using a printing process such as copper gravure, screen printing, gravure, etc., with ink applied only to the opaque portions. In this way, the source elements 18 defined transparent images.
    Figure 3 also shows a specific example of a
    Swell member 18, which is swell member 18a having an image in the form of a transparent line or slit, surrounded by an opaque printed border.
    In one embodiment, each source element 18 is identical. For this reason, the arrangement of the source elements 18 represents an arrangement of identically printed source pixels. In another embodiment, not shown, the source layer 10 comprises different source elements 18, that is to say that the source layer 10 contains at least two different images. Because of different
    Source elements are allowed to change the display if the viewing position is changed.
    It is understood that the images defined by the source elements 18 are from very simple concepts, for example
    17/38 • ··· · · · ···· · · ····· ·· ··· • · · ···· · ·· · ······ · · ··· ·· ···· ··· t ·· · · ·· · · · ·· ·· a line or point image, or complicated concepts such as characters, symbols or representations can be selected.
    An external light source 30 is positioned to illuminate the source layer 10. The external light source 30 has an arbitrary shape, for example point source, fluorescent tube, evenly cloudy sky, etc. In addition, the external light source can illuminate the source layer 10 from an arbitrary angle or direction.
    Each source element 18 transmits the light incident from the light source only through the non-opaque regions of the source element 18. The overall effect is that each source element 18 acts as an embedded light source with a predefined shape that corresponds to the image of the source element, for example the gap shown in Figure 3.
    The substrate 8 is transparent, thereby allowing the light incident on each source element 18 to propagate from the first side 14a of the substrate 8 to the second side 14b. The substrate 8 acts as an intermediate space for the swelling layer 10 and the OVD layer 12. Typically, the substrate 8 originates from a solid material and has a characteristic thickness. For example, a biaxially oriented polypropylene material used in polymer banknotes typically has a thickness between 70 and 100 pm.
    With further reference to FIG. 3, the OVD layer 12 contains an arrangement of the diffractive elements 26
    18/38
    diffractive elements 26 typically correspond to a pixelated OVD microstructure. Essentially, each diffractive element 18 can represent a pixel with a larger diffractive OVD structure. Diffractive elements 26 are configured to be viewed by a viewer 20, typically the naked eye.
    Each diffractive element 26 is assigned to a source element 18. Typically, each diffractive element 26 is uniquely assigned to a source element 18 and vice versa (as shown in FIG. 3), in which each diffractive element 26 is illuminated by its associated source element 18.
    However, alternatives are provided, for example each source element 18 can be uniquely assigned to a fixed number (greater than one) of diffractive elements 26, or each diffractive element 26 can be uniquely assigned to a fixed number (greater than one) of source elements 18. For example, a source element 18 may be arranged to provide an artificial light source for four diffractive elements 26, or a diffractive element 26 may be configured to interact with four separate artificial light sources, each corresponding to a different source element 18.
    Since the source elements 18 provide an embedded light source with a continuous shape that is independent or at least relatively independent of the external light source 30, it is possible to design each diffractive element 26 according to the particular image of the associated source element 18. Each diffractive element 26 has a surface relief configured to form an optically variable image when the device is viewed by the naked eye; being the image that is optically
    19/38 • ···· · ·· · • · ·· · · · ·· · ** '*** 1 * 9 ··· * ··' ·· * is variable, with a changing viewing angle of the Device varies in shape and / or brightness. The surface relief of each diffractive element 26 is optionally configured specifically for this diffractive element 26, as a result of which diffractive elements 26 can ultimately have the same surface relief.
    In general, it may be preferred that the linear dimensions of the source elements 18 be less than the space between the source elements 18 and the diffractive elements 26. Typically, the source elements 18 have linear dimensions, roughly half the space between the source elements 18 and the diffractive elements Correspond to elements 26. For example, when used as a security device on a banknote, the gap between the source elements 18 and the diffractive elements 26 is approximately 70 microns. In this example, each source element 18 has two linear dimensions of 30 microns.
    Reference is made to RA Lee, "Generalized curvilinear diffraction gratings I. Image diffraction patterns, OPTICA ACTA, 1983, Vol. 30, No. 3, 267-289 (referred to herein as" GCDG1), where a general theory for curved diffraction gratings , which are illuminated by an arbitrarily spread out diffuse light source. In connection with GCDG1, each source element 18 is effectively an arbitrarily spread out diffuse light source.
    With reference to FIG. 4, the lattice function for a specific diffractive element 26 results from W (x, y) and
    20/38 • · · ··· · · ·· · ·· ····· ·· ··· • · · ···· · ·· · ······ · · ··· ·· ···· ··· · ·· ·· ·· ··· ·· ·· the lattice grooves of the diffractive element 26 are defined by the characteristic equation of the form W (x, y) = n, where “n is the groove index number (ie n = 1,2,3, ....). The
    Figure shows a generalized relationship between the source element 18 (i.e., the light source), the diffraction element 26 and the viewer 20. As in R. A.
    Lee, "Generalized Curvilinear Diffraction Grätings II, OPTICA ACTA 1983, Vol. 30, No. 3, 291-303 (referred to herein as" GCDG2), W (x, y) can also be described as that
    Contour map of an abstract phase surface that is transferred to a planar light source as it passes through or diffracts from the grating groove pattern W (x, y).
    The ray equations for the diffraction grating of geometric optics for the above situation result from:
    X „, 01V p> +« Ί + «»> = - G ~ ih -r. iny ai. dw
    Pi + Wi + Qoi - (1) (2) where (Qoi, Q02) is the coordinates of the center of the
    Are light source coordinate system (ie the center of the associated source element 18), which are at a distance R s from the center of the grating, as shown in Figure 4. The coordinates (w ^ wq) are the coordinates of a specific point on the light source, while (pi, P2) the
    21/38
    Coordinates are the observation point of an eye (or other viewer), which are at a distance R o from
    The center of the grid is located, as also shown in FIG. 4. The parameter G is defined by G ' 1 = βθ 1 + Rg 1 , while h is the diffraction order number and λ is the wavelength of the incident light.
    In GCDG1 and GCDG2 it was shown that the observed stripe pattern (i.e. the set of (x, y) points on the
    Lattice plane that can be observed by observing light at a certain viewing angle on the eye) can be described by an equation of the following form:
    S { Wl , w 2 } (wi + Qoi, w 2 + Q 02 ) = 0 (3) which is the angular shape of the embedded light source in relation to individual points within the light source represented by (w l , w 2 ) , which in turn is defined in relation to the center of the light source, defined by (Qoi, Q02) r. The observed or perceived illuminated points on the grid are calculated by substituting the grid beam equations of equations (1) and (2) into equation (3).
    Consider the example of a generalized one
    Diffraction grating, observed at a normal angle to the plane of the grating and spread by an incoherent polychromatic source in the form of a very thin slit, illuminated by a polychromatic external light source, such as shown in Figure 3, oriented in a direction parallel to the x-axis (as in Figure 4
    22/38
    defined) of the grid. Applying equation (2) in this situation leads to the expression:
    p 2 + Q 02 = y ~ -Äh d - ^ (4) where w 2 = 0 as the gap can be approximated by an infinitely thin line. The coordinate Wi is not for that
    Calculation is used because the gap can also be approximated by a line of infinite length so that equation (1) can be applied evenly to all points in the X direction. Q 02 defines the angle of the source in
    With respect to the direction y and h is the
    Diffraction order number and includes values of h = + 1, + 2, + 3, etc, although usually only the first, and possibly the second, order needs to be included in the calculation for the grids, the brightness or diffraction efficiency of which rapidly decreases with increasing order number.
    For the particular case of a zone plate OVD where W = j4 (x 2 + y 2 ) while "A is a constant, equation (4) gives p 2 + Q 02 = y (p-2A / h4) or y - (p 2 + ¢ 02) / (7 “2AM) what
    G ü describes a series of straight lines (one for each value of “h) parallel to the source line.
    Referring to Figure 5, a detailed view of the interaction between a single source element 18 and the diffractive element 26 is shown. Here the swelling element 18 has the shape of the printed gap from FIG. 3
    23/38
    spaced and opposite source element 18 is diffractive element 26, which is a series of straight lines parallel to the printed nip (source line) of source element 18.
    A particular embodiment is shown in Figure 6. Here, the diffractive elements 26 are configured as diffractive lenses, that is, they act in a similar manner to a concave or convex lens. When coupled to a source element 18 that defines an arbitrary shape (a star in this case), the viewer 20 perceives the same shape (i.e., a star) if that
    Diffraction element 26 is considered.
    For a diffractive element 26 configured as a diffractive lens, the lattice function can have the form W (x, y) - A (x 2 + y 2 ) + Bx + Cy, where "A," B and "C
    Constants are where "A defines the focusing property and" B and "C define off-axis focal points of the diffractive element 26. For example, if "B and" C are both zero, the diffractive element 26 would be a circular diffractive lens, as shown in FIG. 6. Equations (5) and (6) are obtained by substituting this expression for the lattice function in Equations (1) and (2):
    Pi + Wi + Q 01 + ß (5) p 2 + w 2 + Q02 = y - 2AÄhJ + C (6) and substituting them in equation (3) provides the following:
    24/38
    - 2ΑλΚ) + Β - Pr.ytG ' 1 ~ 2AÄh) + C - ρ 2 ) = Ο where the calculation is applied at every point (νν 1 ( ιν 2 ) within the embedded light source. Note that the source equation, was originally a function of (i + T.wü) (see equation (3)), now a function of (x, y) with a linear relationship between the points (w 1 , w 2 ') and (x, y) is.
    The result shows that a diffractive lens matrix, where each diffractive element 26 is described by a lattice function of the form W (x, y) = A (x 2 + y 2 ) + Bx + Cy, an observed diffraction stripe pattern with the same shape as that Image that is defined by its associated source element 18 is generated. The only difference is that the diffractive stripe pattern is an enlarged and / or shifted version of the image (enlarged according to the parameter "A and shifted according to the parameters" B and "C).
    The degree of magnification can be calculated by taking into account the two points (Wx, w 2 ) and (w'i, w ' 2 ) on a source element 18 and observed by the corresponding diffractive element 26 at point (Pi, p 2 ). Substituting equations (5) and (6) gives the observed pixels that appear at (x, y) and (x ', y'). The degree of enlargement can then be determined as follows:
    (f / f,) (1-2AA / IG)
    25/38 »·· · <• · ·· - Ϊ5 · ··· • ·
    Since (7 _1 = Ro 1 + R7 1 and the observed distance Ro is much larger than the thickness of the document substrate R s , it is possible to use the
    Simplify magnification as follows:
    (R s -2AÄh) (9)
    This relationship enables an appropriate selection of the
    Lens focus parameter “A depending on the desired magnification for a specific substrate thickness, wavelength and required image properties.
    The optical device 4 disclosed herein can be manufactured according to the method shown in FIG. 7. A transparent substrate is provided, such as a biaxially oriented polypropylene substrate, and a radiation curable ink is applied to one side of the substrate by a printing process at RCI step 100. The radiation-curable ink is then embossed with an underlay component in the embossing step 101 and cured. The underlay component has a surface profile in relation to the intended surface profile of the OVD layer 12.
    The document 102 occurs simultaneously with, before or after the embossing step 101. The document 102 corresponds to the generation of the source layer 10 by printing an opaque (or essentially opaque) ink on the opposite side of the substrate, the opaque ink being present in areas which the Define source images, does not exist. Typically, it is necessary to register between the diffraction elements 26 and the source elements 24
    26/38
    ·· • · ·· · • ·· · • · • • · • • · • • · • • · • · · • • • · • • · • · • • ·· ·
    ensure what can be achieved using known techniques.
    As can be seen, the method of FIG. 7 requires that an underlay component has been previously created, for example using known electron beam techniques, and that a suitable print pattern has been formulated to produce the source elements 24. Figure 7 shows the optional
    Preparation step 103 for underlay components.
    Typically, the design of the backing component and the print pattern are supported by a computer.
    Usually the intended source images 18 as well as the proposed projected image and the direction of projection are determined. From this, the required grating profile for each diffraction element 26 using
    Calculation methods that implement the relationships described herein are determined.
    Further modifications and improvements can be incorporated without departing from the scope of the present invention.
    27/38
    权利要求:
    Claims (14)
    [1]
    1. Optical device comprising an at least in
    A substantially transparent substrate having a first side comprising a source layer with an array of source elements and a second side comprising a layer of an optically variable device (OVD) with a corresponding arrangement of diffractive elements, each source element being configured to illuminate to provide the first side, through an external light source, with an integrated light source that is a light source that provides light for an associated diffraction element substantially independently of the external light source, and wherein the diffractive elements are configured to produce an optical effect that is observable when the diffractive elements are viewed by a viewer, such as the naked eye when illuminated by the source elements, each diffractive element configured according to the shape of its associated source element.
    [2]
    2. The optical device of claim 1, wherein one or both of:
    a) define the source elements images that are varied between the source elements; and
    b) the surface relief of the diffractive elements is varied between the diffractive elements so that it appears that the observed image changes the magnification and / or moves and / or changes the shape when the
    Viewing angle is changed.
    28/38
    • · • · • ···· • · • · • · • • · • • · • · • · ··· • • • · • · • · • · • • * ·· •
    [3]
    3. Optical device according to claim 2, wherein only the diffractive elements are varied.
    [4]
    4. Optical device according to claim 2, wherein only the source elements are varied.
    [5]
    5. The optical device of claim 1, wherein each source element defines a source image and wherein each diffractive element defines a diffractive focusing element, preferably a diffractive element with a circular or cylindrical zone plate, configured to provide an enlarged and / or shifted projection of the source image of the associated source element provide.
    [6]
    6. The optical device of claim 1, wherein the substrate comprises a characteristic thickness and wherein the surface relief of each diffractive element is determined in part by the characteristic thickness.
    [7]
    7. Optical device according to claim 1, wherein each diffractive element is uniquely assigned to a source element.
    [8]
    8. An optical device according to claim 1, wherein each
    Source element has at least one linear dimension that is less than a space between the source element and its associated diffractive element, preferably approximately half the space.
    [9]
    9. Document, preferably a security document, comprising the optical device according to claim 1.
    29/38 ·· ·· ·· · «·« · ·· • · ♦ · · ·· · · · • · · · ··· · · · · ······ · · * · «·· ···· · · · · • · · · ·· ··· · * · ·
    [10]
    10. The document of claim 9, wherein the document comprises a transparent document substrate, a region thereof corresponding to the same substrate as the optical device, the document preferably further comprising opacifying layers on each side of the document substrate, each not present in overlapping regions , thereby defining a window in which the optical device is located.
    [11]
    11. The document of claim 9, wherein the optical device is separately molded onto the document and attached to the document in a window region, the window being either a transparent portion of the document or corresponding to a distal portion of the document.
    [12]
    12. A method of manufacturing the optical device according to claim 1, comprising the following steps:
    Making an underlay component in an inverted profile on a required OVD layer profile;
    Determining a print pattern that corresponds to a required swelling layer;
    Applying radiation curable ink to a surface of a transparent substrate;
    Embossing the radiation curable ink with the backing component, and curing the radiation curable ink, thereby forming the diffraction layer; and printing the print pattern on an opposite surface of the substrate, preferably congruent with the surface profile of the diffraction layer.
    30/38 ·· ·· ·· • · · • ♦ · • ···
    [13]
    13. The method of claim 12, wherein the embossing step and the pressing step are performed substantially simultaneously.
    [14]
    The method of claim 12, wherein the transparent substrate includes opacifying layers located on each surface, the opacifying layers not being present in the region of the radiation-curable ink, thereby defining a window that includes the optical device.
    Vienna, applicant on November 16, 2017
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    同族专利:
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    AU2015100671A4|2015-06-11|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE3609090A1|1986-03-18|1987-09-24|Gao Ges Automation Org|SECURITY PAPER WITH SECURED THREAD STORED IN IT AND METHOD FOR THE PRODUCTION THEREOF|
    DE102008028187A1|2008-06-12|2009-12-17|Giesecke & Devrient Gmbh|Security element with optically variable element.|
    WO2010121293A1|2009-04-21|2010-10-28|Securency International Pty Ltd|Optically variable device and security document including same|
    JP5747322B2|2011-04-15|2015-07-15|独立行政法人 国立印刷局|Hologram sheet and printing medium|GB201513096D0|2015-07-24|2015-09-09|Rue De Int Ltd|Diffractive security device and method of manufacturing thereof|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    AU2015100671A|AU2015100671B4|2015-05-21|2015-05-21|Diffractive optical device having embedded light source mechanism|
    PCT/AU2016/050384|WO2016183636A1|2015-05-21|2016-05-20|Diffractive device having embedded light source mechanism|
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