WO1995002200A1 - Multiple image diffractive device - Google Patents

Multiple image diffractive device Download PDF

Info

Publication number
WO1995002200A1
WO1995002200A1 PCT/AU1994/000381 AU9400381W WO9502200A1 WO 1995002200 A1 WO1995002200 A1 WO 1995002200A1 AU 9400381 W AU9400381 W AU 9400381W WO 9502200 A1 WO9502200 A1 WO 9502200A1
Authority
WO
WIPO (PCT)
Prior art keywords
diffractive
surface
device
superimposed
device according
Prior art date
Application number
PCT/AU1994/000381
Other languages
French (fr)
Inventor
Robert Arthur Lee
Original Assignee
Commonwealth Scientific And Industrial Research Organisation
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
Priority to AUPL9885 priority Critical
Priority to AUPL988593 priority
Application filed by Commonwealth Scientific And Industrial Research Organisation filed Critical Commonwealth Scientific And Industrial Research Organisation
Priority claimed from AU71175/94A external-priority patent/AU674770B2/en
Publication of WO1995002200A1 publication Critical patent/WO1995002200A1/en

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/18Diffraction gratings
    • G02B5/1842Gratings for image generation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B42BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42DBOOKS; 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
    • B42D25/00Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30Identification or security features, e.g. for preventing forgery
    • B42D25/328Diffraction gratings; Holograms

Abstract

A diffractive device has a surface relief structure which, when illuminated by a light source, generates at least two diffraction images which can be observed from particular ranges of viewing angles around the device. At least one surface region (3) has two or more superimposed diffractive surface structures (1, 2), each of which gives rise to a separate diffraction image or component of a diffraction image. The diffractive device is particularly suitable as anti-forgery security device on banknotes, credit cards, cheques, share certificates and other similar documents.

Description

MULTIPLE IMAGE DIFFRACTIVE DEVICE This invention relates to a multiple image diffractive device. It relates particularly to a diffractive device which, when illuminated by a light source, generates two or more different diffraction images which are observable from different ranges of viewing angles around the device. Although the device may be used in a number of different applications, it has particular applicability as an anti-forgery security device on banknotes, credit cards, cheques, share certificates and other similar documents.

Several different types of diffractive devices which, when illuminated, generate diffractive images are known. In January 1988, an Australian ten dollar banknote was released featuring a diffractive image of Captain Cook. The diffractive grating used in the image was for the most part comprised of substantially continuous lines, and the shapes and configurations of the lines were determined according to optical catastrophe theory in order to generate fine detail in the diffractive image observed.

International patent application PCT/AU90/00395 discloses an alternative method for generating an optical diffraction image. In this case, the diffractive device is divided into a large number of small diffraction grating structures, each of which upon illumination generates in an image plane a picture element or pixel, with the pixels combining to form an overall image in the image plane. According to preferred aspects of the arrangement disclosed, the respective diffraction grating associated with each pixel comprises a plurality of reflective or transmissive grooves or lines which are usually curved. Groove or line curvature determines both local image intensity (eg. shading) and local optical structure stability. Groove or line spacing in each diffraction grating determines local pixel colour properties, with non-primary colours generated by a pixel mixing. Average groove or line orientation determines movement or colour effects. The overall surface structure of each diffraction grating is selected from a palette of different grating types having a limited number of distinct values of average curvature and average spacing.

The nature of a diffraction grating illuminated by a single point source of light is normally such that a diffraction image will be observable from particular viewing angles around the diffractive device, whereas the image will not be observable from other viewing angles. The particular ranges of viewing angles at which a diffraction image generated by a diffraction grating is visible depend upon such parameters as the orientation, spacing and shape of the diffraction grating. Two diffraction gratings having different orientations and other parameters can be placed next to each other on the diffractive device with the result that a diffraction image generated by one of the gratings is visible at various viewing angles around the device, whereas a diffraction image generated by the other grating is visible at other viewing angles. A diffractive device which takes advantage of this fact is disclosed in international application PCT/AU93/00102 entitled "Security diffraction grating with special optical effects". That application discloses, inter-alia, a method of using a regular array of small diffraction gratings to form two or more different images which are viewable from different ranges of angles around the diffractive device. One set of diffraction gratings having similar orientations combines to produce one image which is viewable from a particular range of directions. A second set of diffraction gratings, each of which has a second orientation, combines to produce a second image which is viewable from a second range of viewing angles. A more recent unpublished patent application, Australian provisional application PL 9008 filed 25 May 1993 entitled "Multiple Image Diffractive Device" discloses a similar arrangement, although with each diffraction grating generating a sub-pixel rather than a complete pixel in the image plane with two or more diffraction gratings combining to generate each complete pixel. All of the prior art arrangements which produce multiple images require that each diffraction grating portion (whether associated with complete image, pixel or sub-pixel) be dedicated to producing one image (or component of that image) only. According to the present invention, there is provided a diffractive device having a surface relief structure which, when illuminated by a light source, generates at least two diffraction images which are observable from particular ranges of viewing angles around the device, wherein at least one surface region of the diffractive device has two or more superimposed diffractive surface structures, each of which gives rise to a separate diffraction image or component of a diffraction image. It is preferred that the diffractive device have the following features:

(a) a set of surface regions have two or more superimposed diffractive surface structures;

(b) one of the superimposed diffractive surface structures in each member of the set generates a component of a diffraction image;

(c) the diffraction image components so generated combine to create a diffraction image which is observable from particular ranges of viewing angles around the device; and

(d) the other superimposed diffractive surface structures in the set of surface regions generate images or image components which are observable from different ranges of viewing angles around the device. In one embodiment, the diffractive device of the present invention may comprise a regular array of small surface regions in a manner similar to that described in international application PCT/AU90/00395, the contents of which are incorporated herein by reference. In another embodiment the device may have surface regions in the form of tracks. Another embodiment may use continuous lines shaped and oriented according to optical catastrophe theory as provided in the 1988 Australian ten dollar banknote. Straight line diffraction gratings which generate different diffractive effects by changes in spatial frequency and orientation may also be utilized. When the diffractive device has a number of surface regions, all of the regions may include superimposed diffractive surface structures, such that each surface region contains a composite surface structure which contributes to more than one of the diffraction images generated by the diffractive device. Alternatively, some of the surface regions may include superimposed diffractive surface structures while other surface regions do not. When the pixels are divided into sub-pixels, some or all of the sub-pixels may be associated with superimposed diffractive surface structures.

The invention will hereinafter be described in greater detail by reference to the attached drawings which show an example form of the invention. It is to be understood that the particularity of those drawings does not supersede the generality of the preceding description of the invention.

Figure 1 is a magnified representation of a small surface region which upon illumination generates a single pixel in the image plane, with the surface structure comprising a series of lines or grooves oriented in one particular manner.

Figure 2 shows another magnified small surface region with the lines or grooves oriented in a manner different from that of Figure 1.

Figure 3 shows a surface region having the surface structure of Figure 1 superimposed on the surface structure of Figure 2. Figure 4 shows two diffractive tracks, with differently oriented diffractive surface structures.

Figure 5 shows the two surface structures of Figure 4 superimposed onto a single track. The diffractive device of the present invention has a surface relief structure which, when illuminated by a light source, generates at least two diffraction images which are observable from particular ranges of viewing angles around the device. At least one surface region (3) of the diffractive device has two or more superimposed diffractive surface structures (1,2) each of which gives rise to a separate diffraction image or component of a diffraction image.

In the embodiment illustrated in Figures 1 to 3, there are two overlapping gratings producing two separate optical diffraction images. It is preferred that the individual surface regions be sufficiently small to be below the resolution limit of a human eye (which is about 250 micron) . It is preferred that the pixels be less than 125 micron in any linear dimension, and more preferably about 30 micron by 30 micron.

The superimposed diffractive surface structures illustrated in Figures 1 to 3 may have any suitable shape and configuration. They may have straightline gratings, curved line gratings, circular gratings, polygonal indentations or protrusions, or any combination of these. It is especially preferred that at least some of the diffractive surface structures be of the type described in international application PCT/AU90/00395. Expressed in mathematical terms, such pixel gratings are defined by the equation S(x,y) = kN, where k is a scaling factor, N is an integer and the function S(x,y) is given by:

Si;j(x,y) = Wi;.(x,y) + βijCij(x,y) ... (1) where S..(x,y) is the initial phase function generated by the grating pixel ij when illuminated normally by a collimated monochromatic light wave, W..(x,y) is a carrier wave of non-zero order, C..(x,y) is a function of x,y which varies rapidly with respect to x and y and whose Hessian is not identically zero, i.e. does not vanish identically; β 1.]. is a factor proportional to the assessed chroma or colour intensity of the pixel ij ; and i,j are the co-ordinates of the respective pixels. The Hessian of C.(x,y) is a standard complex derivative expressed as follows: δ2C..(x,y)/δx2 . δ2C. • (x,y)/δy2 - [δ2C.. (x,y)/δxδy]2 In the embodiment illustrated in Figures 4 and 5, at least part of the surface relief structure is arranged in a series of tracks 4, each track having a diffracting surface 5 which generates a component of a diffraction image. In the superimposed tracks shown in Figure 5, two separate image components are generated. In practice, several such composite tracks are arranged side by side. Two complete diffraction images are formed by combining the image components generated by individual composite tracks. Each of tracks 2 may be of any suitable length. It is preferred that each track be greater than 500 micron in length, and for the sake of convenience, it is preferred that each track extend throughout the length of the diffractive device, although there is no requirement that this be the case. In the preferred embodiment illustrated, each of tracks 4 is straight and arranged in parallel side-by-side configuration. In alternative embodiments, the tracks may be arranged in concentric circles or sections of concentric circles, or in many other curved arrangements.

Each of tracks 4 may be of any suitable width. It is preferred that the tracks be sufficiently narrow to be not noticeable to the naked human eye. The limit of resolution of a normal human eye examining a diffractive device at close quarters is about 0.25mm. Accordingly, tracks having a width of less than this amount are unlikely to be separately discernible to the human eye. It has been found that incidental diffractive effects become significant if the width of the track is less than about 4 micron (0.004mm), and accordingly it is preferred that each track be wider than 4 micron. The diffractive surface structures are preferably produced by means of electron beam lithography.

Prior to the present invention, it had been thought that the superimposition of two diffractive structures in the manner described in this specification would result in interference between the two structures to such an extent that the images produced would be unrecognizable. However, experimentation has revealed that this is not the case, and a superimposed diffractive structure resulting in a plurality of separate clear images can be constructed according to the technique of the present invention.

In the embodiment illustrated, the diffractive structures are all line or groove gratings. However, it is not essential that the structures be comprised of lines or grooves; they may alternatively be comprised of polygons arranged in a manner calculated to cause diffraction.

Australian provisional application PL 9008, the contents of which are herein incorporated by reference, describes a multiple image diffractive device in which each pixel is broken down into component sub-pixels. Each sub-pixel is generated by a tiny diffraction grating and provides some image information, but it is only when the sub-pixels are viewed together that the complete image information for any given pixel is present. By way of example, one sub-pixel might represent a red value, another sub-pixel might represent a green value, another sub-pixel might represent a blue value and a fourth sub-pixel might represent a brightness value, so that the four sub-pixels when taken together give complete brightness and colour information for a complete pixel.

Australian provisional application PL 9008 discloses a method of intermingling the sub-pixels of two separate pixels having different orientations and contributing to a different final image. The present invention may be used in conjunction with sub-pixels so that any given diffractive surface region may be comprised of two overlaid diffraction gratings, one referable to a sub-pixel portion of each of two images.

It is to be understood that various additions, alterations and modifications may be made to the parts previously described without departing from the ambit of the invention.

Claims

CLAIMS :
1. A diffractive device having a surface relief structure which, when illuminated by a light source, generates at least two diffraction images which are observable from particular ranges of viewing angles around the device, wherein at least one surface region of the diffractive device has two or more superimposed diffractive surface structures, each of which gives rise to a separate diffraction image or component of a diffraction image.
2. A diffractive device according to claim 1 wherein:
(a) a set of surface regions have two or more superimposed diffractive surface structures;
(b) one of the superimposed diffractive surface structures in each member of the set generates a component of a diffraction image;
(c) the diffraction image components so generated combine to create a diffraction image which is observable from particular ranges of viewing angles around the device; and
(d) the other superimposed diffractive surface structures in the set of surface regions generate images or image components which are observable from different ranges of viewing angles around the device.
3. A diffractive device according to claim 1 or claim 2 having a plurality of surface regions in the form of tracks, at least some of the tracks having two or more superimposed diffractive surface structures.
4. A diffractive device according to claim 1 or claim 2 having a regular array of small surface regions, at least some of the surface regions having two or more superimposed diffractive surface structures.
5. A diffractive device according to any one of claims 1 to 4 wherein at least some of the diffractive surface structures comprise substantially parallel grooves.
6. A diffractive device according to claim 5 wherein at least some of the grooves are curved.
7. A diffractive device according to any one of claims 1 to 4 wherein at least some of the diffractive surface structures comprise indentations in the form of geometrical shapes other than substantially parallel grooves.
8. A diffractive device according to claim 3 wherein each track is between 4 and 250 micron in width, and greater than 500 micron in length.
9. A diffractive device according to claim 4 wherein each small surface region is between 4 and 250 micron in both width and length.
10. A diffractive device substantially as hereinbefore described with reference to the drawings.
PCT/AU1994/000381 1993-07-09 1994-07-08 Multiple image diffractive device WO1995002200A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AUPL9885 1993-07-09
AUPL988593 1993-07-09

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP94920339A EP0746781A1 (en) 1993-07-09 1994-07-08 Multiple image diffractive device
AU71175/94A AU674770B2 (en) 1993-07-09 1994-07-08 Multiple image diffractive device

Publications (1)

Publication Number Publication Date
WO1995002200A1 true WO1995002200A1 (en) 1995-01-19

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1994/000381 WO1995002200A1 (en) 1993-07-09 1994-07-08 Multiple image diffractive device

Country Status (2)

Country Link
EP (1) EP0746781A1 (en)
WO (1) WO1995002200A1 (en)

Cited By (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995021747A1 (en) * 1994-02-14 1995-08-17 Commonwealth Scientific And Industrial Research Organisation Diffractive device with enhanced anti-copying protection
EP0756945A1 (en) * 1995-07-31 1997-02-05 National Bank Of Belgium Colour copy protection of security documents
AU679333B2 (en) * 1994-02-14 1997-06-26 Commonwealth Scientific And Industrial Research Organisation Diffractive device with enhanced anti-copying protection
US5825547A (en) * 1993-08-06 1998-10-20 Commonwealth Scientific And Industrial Research Organisation Diffractive device for generating one or more diffracting images including a surface relief structure at least partly arranged in a series of tracks
US5912767A (en) * 1993-11-23 1999-06-15 Commonwealth Scientific And Industrial Research Organisation Diffractive indicia for a surface
US5969863A (en) * 1996-01-26 1999-10-19 Electrowatt Technology Innovation Corp. Surface pattern including light-diffracting relief structures
WO2000041124A1 (en) * 1998-12-30 2000-07-13 Chao Liu Invisible graphics context identifying system and fabrication method thereof
WO2002003109A1 (en) * 2000-07-03 2002-01-10 Optaglio Limited Optical security device
US6600603B1 (en) 1999-12-17 2003-07-29 Qinetiq Limited Textured surface
US6765704B2 (en) 2000-07-03 2004-07-20 Optaglio Limited Optical device
WO2005002872A1 (en) * 2003-07-07 2005-01-13 Commonwealth Scientific And Industrial Research Organisation A method of forming a diffractive device
US6876473B2 (en) 2000-07-03 2005-04-05 Optaglio Limited Device with anti-counterfeiting diffractive structure
WO2006013215A1 (en) * 2004-08-06 2006-02-09 Optaglio Sro A method of creating a three-dimensional image, a diffractive element and method of creating the same
WO2006061586A2 (en) 2004-12-06 2006-06-15 De La Rue International Limited Improved hologram
US7199911B2 (en) 2000-07-03 2007-04-03 Optaglio Ltd. Optical structure
US7246824B2 (en) 2000-06-01 2007-07-24 Optaglio Limited Labels and method of forming the same
US7358513B2 (en) * 2001-07-17 2008-04-15 Optaglio Ltd. Optical device and method of manufacture
US7385699B2 (en) 2003-02-22 2008-06-10 Kla-Tencor Technologies Corporation Apparatus and methods for detecting overlay errors using scatterometry
US7387249B2 (en) 2000-06-05 2008-06-17 Optaglio Limited Product verification and authentication system and method
US7551335B2 (en) 2002-11-22 2009-06-23 Ovd Kinegram Ag Optically variable element and the use thereof
US7916343B2 (en) 2003-07-07 2011-03-29 Commonwealth Scientific And Industrial Research Organisation Method of encoding a latent image and article produced
US8174743B2 (en) 2000-07-03 2012-05-08 Optaglio Limited Optical security device
US8562025B2 (en) 2002-02-05 2013-10-22 Optaglio Limited Secure data protection optically variable labels and foils
US8749862B2 (en) 2006-03-15 2014-06-10 Dai Nippon Printing Co., Ltd Method for preparing a hologram recording medium
WO2014086715A1 (en) * 2012-12-04 2014-06-12 Sectago Gmbh Security device
WO2014124781A1 (en) 2013-02-12 2014-08-21 Sectago Gmbh Security device
USRE45245E1 (en) 2000-08-30 2014-11-18 Kla-Tencor Corporation Apparatus and methods for determining overlay of structures having rotational or mirror symmetry
US9103662B2 (en) 2001-04-10 2015-08-11 Kla-Tencor Corporation Periodic patterns and technique to control misalignment between two layers
US20160066595A1 (en) * 2013-04-19 2016-03-10 Nestec S.A. Molded food product
US9465148B2 (en) 2005-06-14 2016-10-11 Ovd Kinegram Ag Security document
DE102015110626A1 (en) * 2015-07-01 2017-01-05 Sectago Gmbh An optical security device
US10207531B2 (en) 2013-12-02 2019-02-19 SECTAG GmbH Security device

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Cited By (49)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5825547A (en) * 1993-08-06 1998-10-20 Commonwealth Scientific And Industrial Research Organisation Diffractive device for generating one or more diffracting images including a surface relief structure at least partly arranged in a series of tracks
US5912767A (en) * 1993-11-23 1999-06-15 Commonwealth Scientific And Industrial Research Organisation Diffractive indicia for a surface
WO1995021747A1 (en) * 1994-02-14 1995-08-17 Commonwealth Scientific And Industrial Research Organisation Diffractive device with enhanced anti-copying protection
AU679333B2 (en) * 1994-02-14 1997-06-26 Commonwealth Scientific And Industrial Research Organisation Diffractive device with enhanced anti-copying protection
EP0756945A1 (en) * 1995-07-31 1997-02-05 National Bank Of Belgium Colour copy protection of security documents
US5969863A (en) * 1996-01-26 1999-10-19 Electrowatt Technology Innovation Corp. Surface pattern including light-diffracting relief structures
EP0876629B1 (en) * 1996-01-26 2002-08-14 OVD Kinegram AG Surface pattern
US7010123B1 (en) 1998-12-30 2006-03-07 Chao Liu Invisible graphics context identifying system and fabrication method thereof
WO2000041124A1 (en) * 1998-12-30 2000-07-13 Chao Liu Invisible graphics context identifying system and fabrication method thereof
US6600603B1 (en) 1999-12-17 2003-07-29 Qinetiq Limited Textured surface
US7246824B2 (en) 2000-06-01 2007-07-24 Optaglio Limited Labels and method of forming the same
US7387249B2 (en) 2000-06-05 2008-06-17 Optaglio Limited Product verification and authentication system and method
WO2002003109A1 (en) * 2000-07-03 2002-01-10 Optaglio Limited Optical security device
US6876473B2 (en) 2000-07-03 2005-04-05 Optaglio Limited Device with anti-counterfeiting diffractive structure
US7199911B2 (en) 2000-07-03 2007-04-03 Optaglio Ltd. Optical structure
US6765704B2 (en) 2000-07-03 2004-07-20 Optaglio Limited Optical device
US8174743B2 (en) 2000-07-03 2012-05-08 Optaglio Limited Optical security device
US9702693B2 (en) 2000-08-30 2017-07-11 Kla-Tencor Corporation Apparatus for measuring overlay errors
US9182680B2 (en) 2000-08-30 2015-11-10 Kla-Tencor Corporation Apparatus and methods for determining overlay of structures having rotational or mirror symmetry
USRE45245E1 (en) 2000-08-30 2014-11-18 Kla-Tencor Corporation Apparatus and methods for determining overlay of structures having rotational or mirror symmetry
US9347879B2 (en) 2000-08-30 2016-05-24 Kla-Tencor Corporation Apparatus and methods for detecting overlay errors using scatterometry
US9835447B2 (en) 2001-04-10 2017-12-05 Kla-Tencor Corporation Periodic patterns and technique to control misalignment between two layers
US9476698B2 (en) 2001-04-10 2016-10-25 Kla-Tencor Corporation Periodic patterns and technique to control misalignment between two layers
US9234745B2 (en) 2001-04-10 2016-01-12 Kla-Tencor Corporation Periodic patterns and techniques to control misalignment between two layers
US10151584B2 (en) 2001-04-10 2018-12-11 Kla-Tencor Corporation Periodic patterns and technique to control misalignment between two layers
US9103662B2 (en) 2001-04-10 2015-08-11 Kla-Tencor Corporation Periodic patterns and technique to control misalignment between two layers
US7435979B2 (en) 2001-07-17 2008-10-14 Optaglio Ltd. Optical device and method of manufacture
US7358513B2 (en) * 2001-07-17 2008-04-15 Optaglio Ltd. Optical device and method of manufacture
US8562025B2 (en) 2002-02-05 2013-10-22 Optaglio Limited Secure data protection optically variable labels and foils
US7551335B2 (en) 2002-11-22 2009-06-23 Ovd Kinegram Ag Optically variable element and the use thereof
US7385699B2 (en) 2003-02-22 2008-06-10 Kla-Tencor Technologies Corporation Apparatus and methods for detecting overlay errors using scatterometry
WO2005002872A1 (en) * 2003-07-07 2005-01-13 Commonwealth Scientific And Industrial Research Organisation A method of forming a diffractive device
US7916343B2 (en) 2003-07-07 2011-03-29 Commonwealth Scientific And Industrial Research Organisation Method of encoding a latent image and article produced
WO2006013215A1 (en) * 2004-08-06 2006-02-09 Optaglio Sro A method of creating a three-dimensional image, a diffractive element and method of creating the same
US7796311B2 (en) 2004-12-06 2010-09-14 De La Rue International Limited Security device with multiple holographic or diffraction effect generating structures
WO2006061586A2 (en) 2004-12-06 2006-06-15 De La Rue International Limited Improved hologram
US9465148B2 (en) 2005-06-14 2016-10-11 Ovd Kinegram Ag Security document
US9158281B2 (en) 2006-03-15 2015-10-13 Dai Nippon Printing Co., Ltd. Method for preparing a hologram recording medium
US8749862B2 (en) 2006-03-15 2014-06-10 Dai Nippon Printing Co., Ltd Method for preparing a hologram recording medium
CN104968503B (en) * 2012-12-04 2018-08-14 赛克达戈有限公司 safety equipment
CN104968503A (en) * 2012-12-04 2015-10-07 赛克达戈有限公司 Security device
AU2013354288B2 (en) * 2012-12-04 2017-06-29 Sectago Gmbh Security device
WO2014086715A1 (en) * 2012-12-04 2014-06-12 Sectago Gmbh Security device
US9731538B2 (en) 2013-02-12 2017-08-15 Sectago Gmbh Security device
WO2014124781A1 (en) 2013-02-12 2014-08-21 Sectago Gmbh Security device
CN105339179A (en) * 2013-02-12 2016-02-17 赛克达戈有限公司 Security device
US20160066595A1 (en) * 2013-04-19 2016-03-10 Nestec S.A. Molded food product
US10207531B2 (en) 2013-12-02 2019-02-19 SECTAG GmbH Security device
DE102015110626A1 (en) * 2015-07-01 2017-01-05 Sectago Gmbh An optical security device

Also Published As

Publication number Publication date
EP0746781A1 (en) 1996-12-11
EP0746781A4 (en) 1996-05-28

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