GB2419566A

GB2419566A - Gravure print cylinder with engraved image decoder

Info

Publication number: GB2419566A
Application number: GB0525187A
Authority: GB
Inventors: Michael Keating; Michael E Hughes; Richard A Bates
Original assignee: KEATING GRAVURE SYSTEMS UK Ltd
Current assignee: KEATING GRAVURE SYSTEMS UK Ltd
Priority date: 2003-03-14
Filing date: 2003-03-14
Publication date: 2006-05-03
Also published as: GB0525187D0; GB2399316A; GB0305886D0

Abstract

The invention provides a gravure cylinder comprising an engraved image decoder. The invention further provides a method of printing an image decoder, the method comprising: <SL> <LI>(a) providing a gravure cylinder <LI>(b) incorporating an ink or other colouring agent into the engraved cells of the cylinder; and <LI>(c) effecting co-operation between the cylinder and a substrate to be printed. </SL> The engraved decoder may comprise a two dimensional vectorial grid of parallel curved or straight lines, corresponding to a primary image within which a second hidden image is hidden. The decoder image has a line frequency greater than the frequency of the image to be decoded.

Description

1 2419566

IMPROVEMENTS IN AND RELATING TO GRAVURE PRINTING AND

SECURITY PRINTING

The invention relates to gravure printing cylinders and methods of producing printed images. The invention further relates to methods of producing security images and methods of producing decoder images.

It would be advantageous to provide printed images which incorporate security features which cannot be detected by the naked eye, and preferably copying means such as photocopiers etc, but which can be cheaply and efficiently created using known printing apparatus. *.S.

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It would be further more advantageous to provide methods, * * of manufacturing security images and their corresponding * * I....

decoders, in which the security images and decoders may be :. ** manufactured using similar apparatus, and be printed on * separate substrates or the same substrate and folded over * S to provide image and decoder means. It is an aim of

S S. *

preferred embodiments of the invention to overcome or mitigate at least one problem of the prior art whether or not expressly disclosed herein or not.

Summary of the Invention

According to a first aspect of the invention there is provided a gravure cylinder comprising an engraved image decoder. Suitably the engraved decoder image comprises a vectorial grid of engraved cells having defined line spacing frequency.

Suitably the vectorial grid comprises a two-dimensional array of parallel straight or curved lines (including waves), suitably corresponding to a primary image of a separate image comprising a primary image in which is incorporated a second, preferably hidden image, which is to be decoded, in use.

Suitably the separate image is a printed image on a substrate and preferably comprises a vectorial grid corresponding to the vectorial grid of the engraved image decoder but having a frequency less than that of the decoder image.

Thus suitably the decoder image has a line frequency of >X, wherein X is the frequency of the separate image to be S...

decoded, in use. Preferably the decoder image has a....

frequency of X + X/2 wherein X is the frequency of the.

separate image to be decoded.

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According to a second aspect of the invention there is: ..

provided a method of printing an image decoder, the method.. S...

comprising: (a) providing a gravure cylinder of the third aspect of the invention; (b) incorporating an ink or other colouring agent into the engraved cells of the cylinder; and (c) effecting cooperation between the cylinder and a substrate to be printed.

Suitably the substrate to be printed comprises a transparent or clear substrate, such as a transparent or clear plastics material.

Alternatively the substrate may comprise a clear or transparent portion of an article such as a printed image.

The substrate may comprise a non-printed portion of a security image comprising a first image in which is incorporated a secondary, preferably hidden image, and wherein the vectorial grid of the decoder image corresponds to the first image, as described above.

The deformations in the vectorial grid of the first image, which make up the second image, may comprise cells of increased thickness or depth of cell in the engraved cylinder, or regions of decreased thickness or depth of cell, compared to the vectorial grid cells. *S.S * *

The deformations may produce a secondary image comprising * deformations in the primary image comprising regions of * *S.S*S faintness, boldness, thinner or wider areas, and the like.

Security printing produced by the cylinders and methods of *.

the invention does not necessarily show up on * photocopying, so it may be arranged that photocopies may be made without the copier realising there is a hidden image, but that they would be detectable by the appropriate decoder.

Brief Description of the Drawings

For a better understanding of the various aspects of the invention and to show how embodiments of the same may be put into effect the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a primary image; Figure 2 is a secondary image; Figure 3 is an illustration of part of a surface a gravure engraving cylinder on which is engraved a primary image comprising a first vectorial grid of wavy lines; Figure 4 is an illustration showing part of a gravure cylinder surface of the first aspect of the invention comprising an engraved output image of a primary image of parallel wavy lines in which deformations in the form of a "B" have been added as a secondary image; and Figure 5 illustrates a decoder screen corresponding to the primary image of Figure 1 and gravure engraving cylinder surface of Figure 3. : .. S... * S S...

Description of the Preferred Embodiment *:.:

Figure 1 illustrates a primary image 2 which is a black screen. Figure 2 illustrates a secondary image 4 which is the letter "B".

Figure 3 illustrates a portion of a gravure engraving cylinder surface 6 on which has been engraved a plurality of cells as a primary image 10. The primary image comprises a vectorial grid of parallel curvy lines, in which each curvy line comprises a plurality of spaced apart engraved gravure cells. In order to create a secondary, hidden image 8 within the primary image shown in Figure 3, the gravure cells are altered by increasing/decreasing their width and depth to produce a secondary hidden image "B" within the primary image 10, as shown in Figure 4. The line spacing frequency of the primary image 10 shown in Figure 3 is approximately 225 lines per cm, which is approximately 1.5 times the line frequency of a decoder image which is to be used to decode the output image provided by the primary/secondary image shown in Figure 4.

Figure 5 shows a decoder screen 12 comprising a lenticular screen or grating with a like vectorial grid 14 of the primary image of Figure 3. However, this decoder screen 12 has a vectorial grid in which the frequency of line 5...

spacing is two thirds of the lines spacing of the primary s..' image 10 of Figure 3, that is 150 lines per cm. The.

decoder 12 needs to have a frequency less than that of the *ss5*' primary image engraved onto the gravure cylinder due to limitations of gravure printing, and ink spread etc. * * S...

In use, the gravure printing cylinder surface 6 of Figure.

4, incorporating the primary and secondary image 10, 8 will be contacted with an ink solution such that the gravure cells making up the primary and secondary image 10, 8 will substantially fill with ink. A substrate such as card, paper, plastics, metal etc can then be cooperated with the surface of the gravure cylinder 6 shown in Figure 4 in order that ink is transferred to the substrate to produce an output image on the substrate, the output image comprising the primary 10 and secondary image 8.

To the naked eye, and preferably to photocopiers and other copying equipment, only the primary image 10 can be seen, the wavy line vectorial grid image primary image 10 of Figure 3, which corresponds to the primary image of Figure 1. When it is desired to decode the image in order to show the hidden secondary image 8 of Figure 2, the decoder of Figure 5 is placed on top of the imaged substrate, and aligned such that the vectorial grid of the decoder screen 12 aligns with the vectorial grid of the primary image of the substrate image. In this situation, the deformations in the primary image which comprise the secondary image 8 show through the decoder screen and grating to reveal the hidden secondary image "B".

In other embodiments (not shown) of the invention the decoder screen of Figure 5 may be provided by a gravure.e.

printing cylinder in which the surface is engraved in a vectorial grid corresponding to a primary image of a S.....

printed image, but in which the frequency of the line, spacing in the engraved decoder image is greater than that: of the primary image to be decoded, preferably 1.5 times *".

frequency. Thus the gravure printing cylinder surface 6.

may incorporate an engraved decoder image comprising a vectorial grid corresponding to a primary image, but having a higher frequency of line spacing. The decoder may then be prepared by printing the decoder image from the engraved cylinder by the method described above (incorporating ink within the decoder image applying a substrate to the gravure cylinder in order to transfer the ink to the substrate) . The substrate will preferably be a transparent or clear substrate such as a transparent plastics material, lacquer or varnish. The decoder substrate may then be applied to the output image to be decoded, in order to align the vectorial grid of the decoder image to the primary vectorial grid of the output image in order to reveal a secondary hidden image.

In alternative embodiments, either the output image producible by a gravure printing cylinder of the first aspect of the invention may be printed onto a blank portion of a decoder substrate such that the substrate may then be folded to align the decoder and printed image, or visa versa.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this *. S.

specification, and the contents of all such papers and....

documents are incorporated herein by reference. * *

S.. *** S. S * . . * S. * * . *S.S * S.. * S S *s S

Claims

1) A gravure cylinder comprising an engraved image decoder.

2) A gravure cylinder as claimed in Claim 12 wherein the engraved decoder comprises a vectorial grid of engraved cells having defined line spacing frequency.

3) A gravure printing cylinder as claimed in Claim 13 wherein the vectorial grid comprises a two-dimensional array of parallel straight or curved lines, corresponding to a primary image of a separate image comprising a primary image in which is incorporated a second, hidden image, which is to be decoded, in use. *S.* * S S...

4) A gravure printing cylinder as claimed in Claim 14 wherein the separate image is a printed image on a * : substrate. :...:.

S

5) A gravure printing cylinder as claimed in Claim 15: wherein the decoder image is a line frequency of *. *S*S

greater than X, wherein X is the frequency of the *:: separate image to be decoded, in use.

6) A method of printing an image decoder, the method comprising: (a) providing a gravure cylinder of any one of Claims 1-6; (b) incorporating an ink or other colouring agent into the engraved cells of the cylinder; and (c) effecting co-operation between the cylinder and a substrate to be printed.

7) A method as claimed in Claim 6 wherein the substrate to be printed comprises a transparent or clear substrate.

8) A method as claimed in Claim 6 or 7 wherein the substrate comprises a clear or transparent portion of an article such as a printed image.

9) A method as claimed in Claim 6 or 7 wherein the substrate comprises a non-printed portion of security image comprising a first image in which is incorporated a secondary hidden image.

10) A gravure printing cylinder substantially as described herein, with reference to the accompanying drawings.

11) A method substantially as described herein, with 0*S*** reference to the accompanying drawings. * * S... * ... * . . SS *