WO1996021572A2 - Procede de formation d'une image composite et lamel associee - Google Patents

Procede de formation d'une image composite et lamel associee Download PDF

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Publication number
WO1996021572A2
WO1996021572A2 PCT/GB1996/000010 GB9600010W WO9621572A2 WO 1996021572 A2 WO1996021572 A2 WO 1996021572A2 GB 9600010 W GB9600010 W GB 9600010W WO 9621572 A2 WO9621572 A2 WO 9621572A2
Authority
WO
WIPO (PCT)
Prior art keywords
pattern
lamina
light
patterns
layer
Prior art date
Application number
PCT/GB1996/000010
Other languages
English (en)
Other versions
WO1996021572A3 (fr
Inventor
John Holden
Christoph Dobrusskin
Original Assignee
Debden Security Printing 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 Debden Security Printing Limited filed Critical Debden Security Printing Limited
Publication of WO1996021572A2 publication Critical patent/WO1996021572A2/fr
Publication of WO1996021572A3 publication Critical patent/WO1996021572A3/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/46—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein having more than one photosensitive layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
    • B41M3/14—Security printing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/08—Photoprinting; Processes and means for preventing photoprinting

Definitions

  • This invention relates to a method of forming a composite image arrangement, comprising a pattern and a further pattern, substantially parallel to the first pattern, each comprising a plurality of visually contrasting regions, the patterns being in fixed positions relative one to the other on either side of a light transmissive lamina, the visually contrasting regions of at least one pattern comprising relatively more and relatively less light transmissive regions, the patterns being aligned one to the other such that if viewed together in transmission through the said at least one pattern in a given direction relative to a normal to the plane of the patterns an image is produced which appears using normal vision to be non-random, the pattern and the further pattern being such that if they are viewed in isolation using normal vision each appears substantially random,
  • the invention also relates to a lamina for use in the method.
  • Composite images find particular, though not exclusive, application in the field of security elements for documents of value (such as bank notes, for example) to deter counterfeiting.
  • Simple composite images are employed in bank notes of certain currencies.
  • the nature of the patterns used for example a segmented D in the case of German bank notes
  • the segments are large in scale.
  • the composite image does not change or disappear with the angle of view.
  • Such images have only a limited degree of deterrence to counterfeiting. This is because modem double-side photocopying techniques can provide images having a sufficiently good front to back registration to deceive a significant proportion of the public.
  • images are used with very fine scale elemental areas (made up from, for example, dots having a diameter of approximately 10 micrometers), or images which can change with angle of view, the registration of the front and back patterns becomes critical and difficult to achieve. The registration becomes even more difficult if the two patters are on a pair of thin flexible substrates.
  • Such composite images are disclosed for example in WO 9509731.
  • a method of forming a composite image as defined in the first paragraph above characterised in that the composite image is formed using a lamina having a first layer sensitive to light in a first wave band, a further layer sensitive to light in a different wave band, and an at least partly transparent layer provided therebetween, the method comprising
  • the two patterns can thus be generated almost simultaneously in registration on either side of a light transmissive lamina in a single process which is suitable for large scale manufacturing,
  • the first and further patterns appear substantially random when viewed in isolation . This can give the advantage of making the composite image more difficult to counterfeit
  • the size of the elemental areas and the thickness of the at least partly transparent layer are such that the composite image is visible only for a range of angles to a given direction relative to the normal to the plane of the patterns.
  • a lamina for recording composite images as defined in the first paragraph above comprising a first layer sensitive to light in a first wave band, a further layer sensitive to light in a different wave band, and an at least partly transparent layer provided therebetween.
  • the at least partly transparent layer is preferably constituted by a sheet which carries the first and further light sensitive layers on opposite major surfaces. This can make a further supporting substrate unnecessary.
  • a lamina of this general type for recording X-ray images is disclosed in patent number US 4,585,729.
  • the lamina is a direct X-ray film which is designed to be placed between two sheets of a scintillator which emit visible light when struck by an X-ray photon, and the photosensitive emulsion layers on either side of the supporting substrate are designed to respond to a broad band of visible wavelengths to increase the film speed.
  • the layers on either side of the support are sensitive to light having the same colour.
  • Such a lamina would not form a composite image as described above if used in the present invention.
  • Figure 2 shows a pattern appearing random using normal vision.
  • Figure 3 shows a further pattern appearing random using normal vision.
  • Figure 4 shows a simulation of the image obtained by aligning fig. 2 and fig. 3 and viewing together in transmission.
  • Figure 5 shows a cross-section of a lamina
  • Figure 6 shows a flow diagram of the method used to make the lamina of fig. 5.
  • Figures 1-5 are taken from WO 9509731, and therefore correspond to known composite image arrangements.
  • a composite image arrangement has a pattern comprising visually contrasting regions having a plurality of relatively more and less light transmissive regions numbered 3 and 2 respectively, and a further pattern having visually contrasting regions comprising a plurality of relatively more and less light transmissive regions numbered 4 and 5 respectively, arranged in fixed positions on either side of a light transmissive lamina 1.
  • the patterns both appear random when viewed in isolation using normal vision.
  • the patters are aligned one to the other to give a non-random image (not shown in this Figure) when viewed from position 7 by light from a source 6 passing through the light transmissive lamina 1.
  • Figure 2 comprises a random array of rectangular regions or pixels which have been printed onto a surface of a white paper sheet. The regions are either black or colourless expending upon whether ink has been printed in the region or not
  • Figure 3 also comprises a random array of pixels of the same size (i.e. 50 per square inch) as those in figure 2.
  • both patterns are random information has been encoded into Figure 3 such that when the patients are carefully aligned and viewed in transmission, and image similar to that shown ⁇ Figure 4 (viz. CRL) is seen.
  • Figure 4 is a computer simulation of the combination of the patterns in Figures 2 and 3 when aligned and viewed together in transmission.
  • the patterns are made using a known method comprising the following steps, (a) providing a pattern comprising relatively more and less light transmissive regions, the pattern appearing random using normal vision (i.e. Figure 2), (b) providing an image pattern comprising relatively more and less tight transmissive regions or visually contrasting regions, the image pattern appearing non-random using normal vision (i.e. Figure 1), (c) combining the pattern and the image pattern using a combining function forming a further pattern comprising relatively more and less light transmissive regions, the further pattern appearing random using normal vision (i.e. Figure 3), and (d) aligning the first-mentioned pattern and the further pattern to give an approximation of the image pattern (i.e. Figure 4) when viewed together in transmission.
  • the combining function used to generate, for example, Figure 3 from Figure 1 and Figure 2 is the "exclusive or" function (also known as a modulo two sum). Other more complex functions may be used but are more difficult to generate (for example by programming a computer).
  • Figure 3 By combining Figure 3 with the inverse of Figure 2 (i.e. in which each dark pixel is changed to light transmissive and each light transmissive pixel is changed to dark) a negative image is produced in which the CRL lettering appears dark on a random grey background.
  • the pixel pitch of the two patterns is preferably equal, and is preferably approximately equal to the separation between the two patterns. As an example, with a thickness of 0.004" , the pixels are printed 300 to the inch.
  • the transmitted image is visible if viewed normal to the surface of the sheet. If however, the patterns are viewed at an angle of 30° to the normal the two patterns are apparently displaced by one half pixel. If the first pattern has been appropriately chosen (for example to be random) the transmitted image will effectively disappear. To reproduce this angle dependency, the printing on opposite sides of the bank note must be aligned to better than approximately 0.001". This is beyond the capability of existing photocopy technology and thus makes counterfeiting difficult.
  • the pattern and further pattern have approximately equal numbers of light transmissive pixels and dark pixels, arranging one image to have more dark pixels will make viewing the transmitted pattern easier from the side with the lighter pattern. This will likewise make viewing the image more difficult from the other (darker) side of the lamina.
  • the patterns of the composite image arrangement preferably printed on either side of the sheet of paper simultaneously using equipment which has been very carefully aligned.
  • paper has been used as the light tram missive lamina, other materials such as acetate film or other transparent or translucent materials such as more and less exposed photographic film may be used as alternatives. It is particularly convenient for both patterns to be pixelated - i.e. made up from a plurality of small picture elements which can each have a respective tone or colour value.
  • the pixel pitch is preferably equal for the two patterns the arrangement will work even when the pitches are unequal, provided corresponding parts of the two patterns appear in alignment from the position of an observer.
  • the patterns are formed by malting first and further patterns separately, and then aligning the patterns on either side of a light transmissive sheet.
  • the present invention describes a way of producing the pair of patterns simultaneously or in rapid succession on either side of a lamina using a photographic process which enables separate registration to be dispensed with.
  • the block numbered 100 denotes the first step of the method according to the present invention
  • the box numbered 101 denotes the second step of the method.
  • a plurality of latent patterns is formed by illuminating a lamina (as shown in Figure 7) with light from a master image (201), the lamina (200) having a first layer (202) sensitive to light of a first colour (in the present example a photographic emulsion layer 1 micron thick sensitive to blue light only), a further layer (203) sensitive to light of a different colour (in the present example a photographic emulsion layer 1 micron thick sensitive to red light only) and an at least partly transparent layer (in the present case a polyester sheet (204) 50 microns thick which carries the two light sensitive layers on opposite major surfaces thereof) provided therebetween.
  • a first layer sensitive to light of a first colour
  • a further layer sensitive to light of a different colour
  • an at least partly transparent layer in the present case a polyester sheet (204) 50 microns thick which carries the two light sensitive layers on opposite major surfaces thereof
  • the master image (201) comprises light-transmissive elemental areas (220, 221, 222) having different respective colours, plus opaque areas (223). Collimated light (230) from an optical system (not shown) is made to shine through the master image. This light subsequently passes through the lamina (200). As a result, two different latent patterns (205, 206) are formed almost simultaneously on either side of the light transmissive layer (204)
  • the master image may be a single image having a plurality of elemental areas each having a respective colour (in the present example blue elemental areas and red elemental areas and transparent elemental areas), the colours in the roaster image being such that the first layer carried by the lamina is sensitive to light from at least one elemental area and the further layer is sensitive to light from at least one other elemental area, thereby forming a first latent pattern in the first layer and a further latent pattern in the further layer
  • One such pattern may be that as shown in Figure 4, in which the apparently black areas shown in the Figure in practice have an apparently random pattern of red and blue coloured pixels, and the areas making up the CRL logo in the Figure have an apparently random mixture of red and blue together with transparent pixels which appear white in the Figure.
  • the elemental areas are either red (220), blue (221), transparent (222) or black (223).
  • the master image may comprise, for example, red, blue and white and black pixels which scatter light from an incident white light source on the same side of the image as that of a camera holding the lamina 200.
  • the first pattern may comprise black and white areas as shown in Figures 2 but be photographed through a red filter, then the pattern shown in Figure 3 may be photographed through a blue filter by way of a multiple exposure - without moving the photosensitive lamina between exposures and carefully aligning each pattern prior to each exposure.
  • the latent patterns are developed (in the present case by immersing the lamina in a tank of standard photographic developer in the absence of ambient light to which the light sensitive layers are sensitive) to form a first pattern and a further pattern which together constitute a composite image.
  • the patterns are then fixed in the same way as any other photographic image, rinsed and dried in filtered air.
  • the photographic emulsion layers may be positive or negative working.
  • the sensitivity of the layers and the colours of the master image are arranged such that areas in the blue light sensitive layer corresponding to blue elemental areas of the master image appear dark after processing and all other areas in that layer appear transparent.
  • areas in the red light sensitive layer corresponding to red elemental areas in the master image appear dark after exposure and all other areas in the red light sensitive layer appear transparent after processing.
  • the thickness of the photosensitive layers may be varied over ranges extending from a tenth of a micron to several tens of microns if required.
  • the speed of the photosensitive layers will depend more upon the amount of photosensitive material present in the layers than by their thickness.
  • the wave bands of the light used need not be in the visible pan of the electromagnetic spectrum.
  • ultra-violet light or infra-red light may be used as an alternative or in addition to visible light.
  • the master image need not be light transmissive.
  • the master image may reflect light of different colours which subsequently is made to impinge upon the lamina alternatively or in addition to being light transmissive.
  • the elemental areas of the master image are square dots 30 microns on a side.
  • the elemental areas can, of course, be of any shape and of any size. However, dots between 2 microns across and 300 microns across are preferred.
  • the only real limitation on the smallness of the elemental areas is the resolution of the optical system used to illuminate the master image and lamina.
  • the at least partly transparent layer (204) described above was 50 microns thick, many different thicknesses may be employed as alternatives. Layers with thicknesses in the range 3 - 300 microns are preferred for document protection. The inventors have specifically made embodiments with sheets 100 microns thick. Very thin layers would need to be supported to make handling easier.
  • the size of the elemental areas needs to be approximately equal to the thickness of the at least partly transparent layer (to within say a factor of 3 or 4) if a composite image with an appearance which changes with the angle of view is desired. If a non- variable appearance is wanted then the elemental areas may be correspondingly larger than this.
  • the lamina described in the above description may take the form of a roll of double-sided photographic film, or a sheet of material.
  • the composite images are produced having lateral dimensions of a few millimetres.
  • the images are subsequently attached to a document of value (such as a bank note, for example) by a lamination or bonding process.
  • a document of value such as a bank note, for example
  • Each image may be unique if desired - for example each having a different serial number.
  • polyester sheet has been specifically described above, other materials such as glass or perspex, or thin flexible sheets of plastics materials may be used as an alternative.
  • the use of such images on window panes may form eye-catching displays suitable for advertising purposes. Such displays will have a thicker light transmissive sheet constituted by the window pane, and the elemental areas in the two patterns must consequently be larger.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Printing Methods (AREA)
  • Credit Cards Or The Like (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Laminated Bodies (AREA)

Abstract

La présente invention concerne un procédé de formation d'une image composite qui consiste a) d'une part, à illuminer une lame avec la lumière d'une image maître, ladite lamel possédant une première couche sensible à une lumière d'une certaine couleur, une seconde couche sensible à une lumière de couleur différente, et une feuille de support transparente séparant les deux couches précédentes, l'image maître comportant de nombreux pixels qui possèdent tous une couleur différente, ces couleurs étant choisies de sorte qu'un premier motif latent apparaisse dans la première couche et de sorte qu'un second motif latent (différent du premier) apparaisse dans la deuxième couche, et b) d'autre part, à révéler les motifs latents pour former une image composite. Il est alors possible de générer simultanément ces motifs dans une opération de cadrage en un processus unique. L'invention concerne également une lame d'enregistrement d'images qui comporte une première couche sensible à une lumière d'une première couleur, une seconde couche sensible à une lumière d'une seconde couleur et une couche transparente séparant les deux couches précédentes.
PCT/GB1996/000010 1995-01-07 1996-01-04 Procede de formation d'une image composite et lamel associee WO1996021572A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9500290.3 1995-01-07
GB9500290A GB2296784A (en) 1995-01-07 1995-01-07 A method of forming a composite image & a lamina for use in the method

Publications (2)

Publication Number Publication Date
WO1996021572A2 true WO1996021572A2 (fr) 1996-07-18
WO1996021572A3 WO1996021572A3 (fr) 1996-09-06

Family

ID=10767716

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/000010 WO1996021572A2 (fr) 1995-01-07 1996-01-04 Procede de formation d'une image composite et lamel associee

Country Status (2)

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GB (2) GB2296784A (fr)
WO (1) WO1996021572A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1580025B1 (fr) 2004-03-26 2015-10-14 Hueck Folien Ges.m.b.H Elément de sécurité avec des éléments optiques reconnaissables sous un angle d'observation particulier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AUPQ128899A0 (en) * 1999-06-30 1999-07-22 Securency Pty Ltd Security article including diffractive optic filter

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB315528A (en) * 1928-05-26 1929-07-18 Waterlow And Sons Ltd Improvements in the printing of cheques and like documents
DE548508C (de) * 1929-11-13 1932-08-04 Rudolf Fischer Dr Verfahren zur Herstellung von gleichzeitig als Aufsichts- und Durchsichtsbild verwendbaren Photographien
FR936847A (fr) * 1943-05-11 1948-07-30 Procédé pour obtenir un papier photographique spécial, en vue de la reproduction directe de photographies sur les documents, photographies visibles des deux côtés du papier
FR1000127A (fr) * 1949-11-05 1952-02-08 Lumiere Soc Perfectionnements aux matériaux photographiques à double face sensible
DE2511368A1 (de) * 1974-04-02 1975-10-16 Gao Ges Automation Org Faelschungsgesicherter informationstraeger, z.b. ausweiskarte
DE3208204A1 (de) * 1982-03-06 1983-09-15 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München Druckverfahren zur sicherung von banknoten und dokumenten gegen unbefugtes nachmachen
GB2282563A (en) * 1993-10-07 1995-04-12 Central Research Lab Ltd A composite image arrangement for documents of value

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB884420A (en) * 1958-09-26 1961-12-13 Bush & Rank Cintel Ltd Improvements in or relating to methods for the simultaneous photographic recording of different phenomena as superimposed images
US4455369A (en) * 1982-10-19 1984-06-19 Purro Norina M Method of creating image on light sensitive sheet

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB315528A (en) * 1928-05-26 1929-07-18 Waterlow And Sons Ltd Improvements in the printing of cheques and like documents
DE548508C (de) * 1929-11-13 1932-08-04 Rudolf Fischer Dr Verfahren zur Herstellung von gleichzeitig als Aufsichts- und Durchsichtsbild verwendbaren Photographien
FR936847A (fr) * 1943-05-11 1948-07-30 Procédé pour obtenir un papier photographique spécial, en vue de la reproduction directe de photographies sur les documents, photographies visibles des deux côtés du papier
FR1000127A (fr) * 1949-11-05 1952-02-08 Lumiere Soc Perfectionnements aux matériaux photographiques à double face sensible
DE2511368A1 (de) * 1974-04-02 1975-10-16 Gao Ges Automation Org Faelschungsgesicherter informationstraeger, z.b. ausweiskarte
DE3208204A1 (de) * 1982-03-06 1983-09-15 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München Druckverfahren zur sicherung von banknoten und dokumenten gegen unbefugtes nachmachen
GB2282563A (en) * 1993-10-07 1995-04-12 Central Research Lab Ltd A composite image arrangement for documents of value

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1580025B1 (fr) 2004-03-26 2015-10-14 Hueck Folien Ges.m.b.H Elément de sécurité avec des éléments optiques reconnaissables sous un angle d'observation particulier

Also Published As

Publication number Publication date
GB2296784A (en) 1996-07-10
GB9600090D0 (en) 1996-03-06
GB2296785A (en) 1996-07-10
GB2296785B (en) 1997-04-09
GB9500290D0 (en) 1995-03-01
WO1996021572A3 (fr) 1996-09-06

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