Technical Field

The present invention relates to a substrate, which may in some particular embodiments be used for providing an anti-counterfeit image.

Background

Counterfeiting of products is a serious problem for both producers of such products and the general public. Counterfeit products are often not as well made as the genuine article and can sometimes even be hazardous, particularly if they contain electronics, as they will not likely conform to any recognised safety standards. Counterfeiting of Government issued documents, such as passports and money, is also a serious problem.

One way to help prevent counterfeiting is to provide optical security features on products or documents to indicate that they are authentic. Such optical security features are difficult to reproduce and may be referred to as anti-counterfeit images. The term "anti-counterfeit image" is used herein to denote any image that has a recognisable meaning, to either a human or machine, but that is difficult to reproduce. Examples of anti-counterfeit images include images contained in holograms or watermarks. The image may be of an object, such as a dove, as seen on Visa credit cards. The image may comprise patterns that are recognisable by a person or computer, such as a bar code or Q-code. Alternatively, the image may comprise letters or numbers, and may spell a word. Such images may be easily recognisable by a human, and can provide a quick visual confirmation as to whether an article containing an anti-counterfeit image is genuine.

Anti-counterfeit images are routinely used in articles such as money, passports, certificates, official documents, etc. Due to the difficulty in reproducing anti-counterfeit images, their use helps to prevent unauthorised third parties from copying products which contain anti-counterfeit images. For example, a counterfeiter may find it relatively easy to generally reproduce an article, but would find it very difficult to reproduce the anti-counterfeit image. Lack of the anti-counterfeit image on the article, or a poor copy of the anti-counterfeit image, indicates to an end user that the article is likely not genuine.

Summary of the Invention

According to a first aspect of the present invention, there is provided a substrate. The substrate comprises a first deposit of a first material on the substrate, the first deposit defining raised lines on the substrate, the raised lines having a first thickness defining a raised surface on the substrate. The substrate further comprises a second deposit of a second material on the substrate, the second deposit defining second lines on the substrate, wherein a thickness of the second lines is less than a thickness of the raised lines. There is a first positional relationship between a first portion of the raised and second lines, and a second positional relationship between a second portion of the raised and second lines, such that, when viewed from a first angle, the first portion of the second lines is visible, and second portion of the second lines is not visible so as to form a first visual property, and when viewed from a second angle, the first portion of the second lines is not visible, and the second portion of the second lines is visible, so as to form a second visual property. Advantageously, the substrate of the first aspect can provide an anti-counterfeit image which is created solely from the interaction of material deposited onto the substrate, and does not rely on providing a substrate with an embossed surface.

The first visual property and the second visual property may relate to a visual property of an image, such as an anti-counterfeit image, where the image is created due to the arrangement of the raised and second lines.

It is to be understood that the term thickness means height above a surface of the substrate.

In an embodiment, the first positional relationship comprises a first part of a second line being deposited on a first side of a raised line, and the second positional relationship comprises a second part of the second line being deposited on a second side of the raised line.

The change from the first to the second positional relationship may be as a result of a deviation in one of the raised or second lines. For example, the raised line may comprise a disjoint, i.e. a part of a raised line may be shifted, or deviated, horizontally with respect to another part of the raised line, and the second line may run between the two parts of the raised line. In order to create the appearance of complex images, there may be many such deviations along the length of a given raised or second line.

In an embodiment, the raised lines provide an optical barrier between a viewer and the first part of the second lines when viewed from the first angle, and provide an optical barrier between the viewer and the second part of the second lines when viewed from the second angle.

That is, the raised lines i.e. the thicker lines, or lines having a greater height above the surface of the substrate, interrupt the line of sight between the viewer and the first part of the second lines when viewed from the first angle, thus preventing a user from being able to view the first part of the second lines from the first angle. In an embodiment, the raised lines

In an embodiment, a raised line is deposited next to second line so as to form a composite line. For example, the substrate may comprise many composite lines, each comprising a raised line and a second line. The term "next to" is taken to mean that the second line is deposited substantially adjacent the raised line. The second line may physically contact the raised line. The second line may overlay a part of the raised line. In an embodiment the raised line of a composite line may act as the selective optical barrier for the second line of the composite line. In an embodiment, the first visual property may be an inverse of the second visual property. Optionally, the inverse may be an inversion of any of a contrast or colour.

For example, if the first visual property appears as an image having two regions, such as a main image and a background, where the main image is relatively light and the background is relatively dark, then the second visual property would appear as the main image being relatively dark and the background being relatively light. This is an example of contrast inversion. The location of the main image may correspond with the first portion the background may correspond with the second portion. In an embodiment, at least one of the raised lines may comprise multiple layers of the first material. Optionally at least a first layer of the multiple layers has a greater width than a second layer of the multiple layers, so as to define a step in the at least one of the raised lines.

In an embodiment, the at least one of the raised lines comprises a step in both sides of the raised line.

In an embodiment, at least one of the second lines is deposited in at least one of the steps in the at least one of the raised lines. In this way, the second line may be arranged to overlay a part of the raised line.

In an embodiment, the first material may comprise a high build ink. In an embodiment, the first material may comprise a UV ink.

In an embodiment, the second material may comprise a UV ink.

In an embodiment, the raised and second lines may be different colours. For example, the raised lines may be white and the second lines may be black, or vice versa.

Brief Description of Drawings

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 illustrates a plan view of a substrate having raised lines deposited on its surface;

Figure 2 illustrates a side view of the substrate of Figure 1 ;

Figure 3 illustrates a plan view of the substrate of Figure 1 having the raised lines and second lines deposited on its surface;

Figure 4 illustrates a side view of the substrate of Figure 3;

Figure 5A illustrates a perspective view of the substrate of Figure 3;

Figure 5B illustrates an anti-counterfeit image visible on the substrate of Figure 3 when viewed from a first angle; Figure 5C illustrates the anti-counterfeit image visible on the substrate of Figure 3 when viewed from a second angle;

Figure 6 illustrates an alternative arrangement of the first and second lines;

Figure 7 illustrates a schematic of a printer suitable for printing the first and second lines on the substrate;

Figure 8 illustrates a plan view of a substrate having an alternative arrangement of the first and second lines; and

Figure 9 illustrates a side view of the substrate of Figure 8. Detailed Description

With reference to Figures 1 to 9 there will now be described a substrate on which is provided an anti-counterfeit image. Figure 1 shows a plan view of a substrate 1 . The substrate 1 may comprise any suitable material for printing on, such as paper, card, plastic, and metal, for example. A first deposit of a first material is printed, or otherwise applied, onto a surface 1 a of the substrate 1. The first deposit comprises a set of raised lines 2 that are printed onto the surface 1 a of the substrate 1 as shown in Figure 1 (not to scale). A high build ink is used to print the raised lines 2 such that the raised lines 2 stand proud of the surface 1 a of the substrate 1 with a thickness Ti as shown in Figure 2, which shows a side view of the substrate 1 of Figure 1 . Once the high build ink is deposited onto the substrate 1 , it is at least partially cured to stop the ink spreading across the substrate's surface 1 a. For example, if the high build ink is a UV high build ink, it is 'pinned' by a UV torch after printing. The raised lines 2 are printed with a predetermined frequency, such that there is a general distance D between each of the raised lines 2. The distance D may be less than 0.5 mm, for example.

The raised lines 2 are printed such that some of the raised lines 2 contain deviations. In the example shown in Figure 1 , the deviations take the form of splitting and/or perpendicularly shifting sections of the raised lines 2 by a distance less than the distance D to create 'un-deviated' sections 2a, and 'deviated' sections 2b.

In Figure 1 , the deviated sections 2b have been deviated by shifting to the right with respect to their respective un-deviated sections 2a when viewed as in Figure 1. The distance of the shift is less than D, such that the overall effect of the raised lines 2 is to produce a series of lines that generally repeat with a frequency of 1/D. While the deviation has been described in Figure 1 as a disjoint, i.e. splitting the raised line 2 into two separate sections 2a, 2b, the deviation may be continuous, such that the deviated section 2b is connected to an the un-deviated section 2a, as shown in the example of Figure 6. Furthermore, while only one deviation is shown per raised line 2 that is deviated, a raised line 2 may have multiple deviations along its length which alternate about a central axis. For example, a line may be split into three parts, where the first and second parts are offset as shown in Figure 1 , and the third part is arranged so as to be in line with the first part.

The deviations in the raised lines 2 are arranged to encode an anti-counterfeit image which is generally only visible with the use of an optical decoder. Figure 3 shows the substrate 1 where a control screen comprising a uniform set of parallel control lines 3 has been printed, or otherwise applied, onto the surface 1a of the substrate 1. The control screen provides an optical decoder. The colour of the control lines 3 is different from the colour of the raised lines 2 and of the un-deviated and deviated sections 2a, 2b. The control lines 3 have the same frequency 1/D as the raised lines 2, i.e. the distance between each control line 3 of the control screen is D. The control lines 3 of the control screen are arranged such that they are printed adjacent the raised lines 2. Where the raised lines 2 are split into multiple parts, the control lines 3 are arranged such that they are printed between the un-deviated sections 2a and the deviated sections 2b. By printing the control lines 3 adjacent the raised lines 2, the raised lines 2 and the control lines 3 effectively form a series of parallel composite lines 4 along the surface 1a of the substrate 1. At least some of the raised and control lines 2, 3 are arranged such that there is a first positional relationship between a first portion of the raised and control lines 2, 3 within the composite line 4, and a second positional relationship between a second portion of the raised and control lines 2, 3 within the composite line 4. The first portion relates to the parts of the composite line 4 containing the un-deviated part 2a, where a part of the control line 3 is deposited on a side of the un-deviated section 2a of the raised lines 2 (on the right side of the un-deviated section 2a when viewed as in Figure 3). The second portion relates to the parts of the composite line 4 containing the deviated sections 2b, where a part of the control line 3 is deposited on a side of the deviated section 2b of the raised lines 2 (on the left side of the deviated sections 2b when viewed as in Figure 3). Figure 4 shows a side view of the substrate 1 of Figure 3, and in particular, shows that the control lines 3 have a thickness T ₂ which is less than the thickness ΤΊ of the raised lines 2. In other words, the control lines 3 of the control screen are shorter in height than the raised lines 2. As the control lines 3 are arranged to have a thickness less than the raised lines 2, the material used to form the control lines 3 may, but does not necessarily need to, comprise a high build ink, i.e. the control lines 3 may be formed by depositing a lower build ink than used for the raised lines 2, or depositing a normal (e.g. inkjet) ink onto the substrate 1. Therefore, while the figures show the control lines 3 having a thickness on the same scale as the raised lines 2, it will be appreciated that the control lines 3 may be substantially flat.

Figure 4 shows arrows A and B, which indicate different angles from which the substrate 1 may be viewed by a viewer. As can be seen in Figure 4, when the substrate 1 is viewed by a viewer from the direction indicated by arrow A, the raised lines 2, and the un-deviated sections 2a, of a given composite line 4 generally block the line of sight between the viewer and the control lines 3 of that composite line 4 in the first portion. This is due to the height (i.e. thickness) of the raised lines 2 being greater than that of the control lines 3. However, the deviated sections 2b of a given composite line 4 do not block the line of sight between the viewer and the control lines 3 of that composite line 4 in the second portion. This is because the deviated sections 2b are situated on an opposite side of a given control line 3 from the side of the viewer when viewed from the angle A. Conversely, when the substrate 1 is viewed by the viewer from the angle indicated by arrow B, the control lines 3 of a given composite line 4 in the first portion are not obstructed by the raised lines 2 and the un-deviated sections 2a of that composite line 4. This is because the raised lines 2 and the un-deviated sections 2a are now located on the opposite side of second lines 3 from the side on which the viewer is located. However, the deviated sections 2b of a given composite line 4 are located on the same side of the control lines 3 of that composite line 4 as the viewer, and thus the deviated sections 2b obstruct the line of sight between the viewer and the control lines 3 in the second portion. In other words, the raised lines 2, un-deviated sections 2a and deviated sections 2b act as selective optical barriers, which prevent certain parts of the control lines 3 of the control screen from being viewed at one angle, but do not prevent those parts from being viewed when at a second angle. This arrangement allows different parts of the control screen to be visible or not visible to a viewer, depending on the direction from which the substrate 1 is viewed. The deviations in the raised lines 2 relative to the control lines 3 are arranged so as to form an anti-counterfeit image when viewed from directions A and B. Furthermore, by changing view point from A to B, a visual property of the anti-counterfeit image will appear to change. For example, if the colour of the raised lines 2, including the un- deviated and deviated sections 2a, 2b are white, and the colour of the control lines 3 are black, the image formed by the composite lines 4 will undergo an inversion in contrast when viewed from angle A and then from the angle B, i.e. the anti-counterfeit image will look lighter against a darker background in one position, and darker against a lighter background in another position.

An example of this is shown in Figures 5A, 5B and 5C. Figure 5A shows a perspective view of the substrate 1. The surface 1 a of the substrate 1 is provided with many printed lines of the type described above (the surface 1 a is shown as having a dotted surface for illustration purposes only). Arrows A and B are also shown to indicate different directions from which the substrate 1 may be viewed. Figure 5B shows a perspective view of the substrate 1 when the substrate 1 is viewed by the viewer from angle A. In this example, the deviations have been chosen such that the anti- counterfeit image appears as a circle 5 on a background 6.

From the viewpoint of angle A, the circle 5 appears light on a dark background 6. In this example, the raised lines 2, including the un-deviated and deviated sections 2a, 2b, are white, while the control lines 3 of the control screen are black. In the region defining the circle 5, the white deviated sections 2b of a given composite line 4 obstruct the black control lines 3 of that composite line 4, such that the second portion appears white (where, as above, the second portion is a portion containing the deviated sections 2b). However, in the background 6, the control lines 3 of the control screen are not obstructed by the raised lines 2 or the un-deviated sections 2a, such that the control lines 3 are visible to the viewer in the first portion (where, as above, the first portion is a portion containing the un-deviated sections 2a). The first portion therefore appears darker due to the visibility of the black control lines. This arrangement leads to the circle 5 appearing to be lighter in colour than the background 6. Figure 5C shows a perspective view of the substrate 1 when the substrate 1 is viewed by the viewer from angle B. The circle 5 now appears darker relative to the lighter background 6. From this position, in the region defining the circle 5 the white deviated sections 2b of a given composite line 4 do not obstruct the black control lines 3 of that composite line 4, and thus the control lines 3 are visible in the second portion. However, in the region defining the background 6, the control lines 3 of a given composite line 4 are obstructed by the raised lines 2, and the un-deviated sections 2a, of that composite line 4. Therefore, as the substrate 1 is viewed from different directions, the circle 5 undergoes a contrast inversion with respect to the background 6. In other words, the first and second portions undergo contrast inversion as the angle of view is changed.

The colour of the surface 1 a of the substrate 1 may be chosen to help accentuate the anti-counterfeit image. For example, the surface 1 a may be the same colour as either the raised lines 2, including the un-deviated and deviated sections 2a, 2b, or the control lines 3. Thus, the overall visual effect of the anti-counterfeit image may be an amalgamation or mixture of the colour of the surface 1 a of the substrate 1 , raised lines 2, un-deviated sections 2a, deviated sections 2b and control lines 3. Alternatively, the control lines 3 may be defined by the colour of the surface of the substrate. That is, the control lines 3 may be provided by the relationship between the raised lines 2, un- deviated sections 2a and deviated sections 2b, and exposed areas of the surface 1 a of the substrate 1 .

Alternatively, the raised lines 2, including the un-deviated and deviated sections 2a, 2b, and the control lines 3 may be the same colour, and the surface 1 a of the substrate 1 may be a different colour. For example, the surface 1 a of the substrate 1 may be white, and the raised lines 2, un-deviated and deviated sections 2a, 2b and control lines 3 may be black. In this example, when viewed from direction B, the black raised and control lines 2, 3 of a given composite line 4 in the first portion will combine to form a composite line 4 that appears as a relatively thick black line, i.e. the thickness Ti of the raised lines 2 (and un-deviated sections 2a) act as an optical barrier to the white surface 1 a of the substrate 1 on the opposite side of the raised line 2 from the viewer. This will give the first portion a generally darker appearance. However, as the deviated sections 2b are on an opposite side of the control line 3, the black deviated sections 2b of a given composite line 4 in the second portion will act as an optical barrier to the black control line 3 of that composite line 4, and so the composite line 4 will appear as a relatively thin black line on a white background. In other words, the black control line 3 will not be visible, and so will not combine with the deviated section 2b to form a thick line. This will give the second portion a generally lighter appearance. This arrangement will be reversed when viewed from angle A, such that the black raised lines 2 (and un-deviated sections 2a) will act as optical barriers to the control lines 3 in the first portion to give the appearance of the composite lines 4 being relatively thin, and the black deviated sections 2b will combine with the control lines 3 in the second portion to form a relatively thick line.

While the control lines 3 of the control screen have been described as being printed adjacent the raised lines 2 in order to form composite lines 4, in other embodiments, the control lines 3 may be printed directly onto a part of the raised lines 2, as shown in Figure 6. Figure 6 shows a magnified perspective view of a composite line 4. In this example, the raised line 2 has an un-deviated portion 2a and deviated portion 2b, however the raised line 2 is formed from a continuous portion of printed material, i.e. there is no disjoint between the un-deviated and deviated portions 2a, 2b as in the examples of Figures 1 to 4. The raised line 2 comprises multiple layers of differing widths. A first, base, layer 7 is printed directly onto the substrate 1 and is wider than a second, middle, layer 8, which is wider than a third, top, layer 9. The difference in the width of the multiple layers define a first step 10 and a second step 1 1 on either side of the raised line 2.

As shown in Figure 6, the control line 3 is printed so as to run along the first step 10, i.e. the control screen is printed directly onto the raised lines 2. As the deviation in the raised line 2 is not a disjoint of the line as in the examples shown in Figures 1 to 4, the control line 3 is printed so as to run over the deviation, by being printed in the second step 1 1 and over the top layer 9 of the raised line 2. In alternative embodiments the control line 3 may be disjointed in the region of the deviation in the raised line, such that the control line 3 is only printed in the first step 10.

Each of the layers 10, 11 , 12 of the raised line 2 are pinned after printing by a UV torch, in order to stop the spread of ink and also to create a firmer layer for the next layer to be printed on. Figure 7 shows a schematic diagram of a printer 13 suitable for printing multi-layered lines onto the substrate 1 (not shown in Figure 7). The printer 13 has four inkjet heads, where a first, second, and third inkjet head 14, 15, 16 are arranged to deposit a high build UV ink onto the substrate 1 , and a fourth inkjet head 17 is arranged to print the control lines 3. Each of the first, second and third inkjet heads 14, 15, 16 has a respective UV "pin" 18, 19, 20 which is used to partially cure the UV high build ink once it is deposited by the respective inkjet head 14, 15, 16. The printer 13 also comprises a UV torch 21 which is used to fully cure the ink after all of the layers of ink have been deposited on the substrate 1.

In operation, a material, such as the substrate 1 , is fed through the printer 13 in the direction indicated by arrow C. The first inkjet head 14 prints directly onto a surface of the material to form the relatively wide base layer 7. Once the base layer 7 has been deposited, the first pin 18 partially cures the base layer 7 to stop the ink spreading and create a firm layer for the next layer to be printed on. The second inject head 15 then prints the middle layer 8 directly onto the base layer 7. Once the middle layer 8 has been deposited, the second pin 19 partially cures the middle layer 8. The third inkjet head 16 then prints the top layer 9 directly onto the middle layer 7, and the third pin 20 partially cures the ink of the top layer 9. Once the first, second and third layers 7, 8, 9 have been deposited and partially cured, the fourth inkjet head 17 prints the control lines 3 of the control screen directly onto the first, second and third layers 7, 8, 9. The ink deposited on the substrate 1 is then fully cured by a UV torch.

In an embodiment, the printer 13 can print at a speed of around 40 metres per minute, that is, 40 meters of material may be printed on per minute. In a particular embodiment, the printer 13 is a high resolution inkjet system having a resolution of 720 dpi, and more preferably 1200 dpi or greater. However, it will be appreciated that the inkjet system may have a lower resolution e.g. around 360 dpi. In a particular embodiment, the printer 13 is capable of printing at 40 Ipi. In another embodiment, the printer is capable of printing at 50 Ipi. It will be appreciated by the skilled person that the printer may be capable of printing at a higher resolution than 50 Ipi, such as 100 Ipi, 150 Ipi, 200 Ipi, and greater.

While the printer 13 has been described as printing lines comprising multiple layers having different widths as shown in Figure 6, it will be appreciated that the printer 13 may also print layers that do not have differing widths, so as to achieve a raised line 2 similar to that shown in Figures 1 to 4. Furthermore, the printer 13 is also suitable for printing the raised lines 2 shown in the embodiments of Figures 1 to 4 where the raised lines 2 are not multi-layered, i.e. the single layer of lines 2 shown in Figures 1 to 4 may be printed using only one inkjet head.

Advantageously, embodiments of the invention provide an anti-counterfeit image on a substrate which is created solely from the interaction of material printed onto the substrate, and does not rely on providing a substrate with an embossed surface. This allows greater flexibility when creating anti-counterfeit images. An embossed surface is not required to create the anti-counterfeit image, and furthermore, the arrangement of the anti-counterfeit image is not limited to the dimensions of the embossing. This allows a user to create and print bespoke anti-counterfeit images "on the fly" on a flat surface.

Embodiments of the invention have been described. Variations and modifications will suggest themselves to those skilled in the art without departing from the scope of the inventions as defined by the appended claims.

For example, the skilled person will readily recognise while the use of UV ink has been described, it will be appreciated that other, non UV, inks may be used to create any of the lines 2, 3. For example, other "3D printing" techniques (or additive manufacturing) may be used, in which materials such as plastics, glass or metals may be "printed" onto a surface.

While Figure 1 shows the raised line 2 comprising three layers, 7, 8, 9 the skilled person will recognise that there may be any number of layers, including just one layer. Furthermore, while the layers have been depicted as having successive widths that reduce in size, it will be appreciated that some or all of the layers may have the same width. While the control lines 3 have been shown as being applied to the first step 10, the skilled person will recognise that the control line 3 may be deposited in any step, or onto the substrate 1 itself.

While it has been described that the deviations encoding the anti-counterfeit image are formed within the raised lines 2, the skilled person will recognise that the control lines 3 of the control screen may contain the deviations. An example of this is shown in Figures 8 and 9, which show a plan and side view of the substrate 1 respectively. The raised lines 2 (having thickness Ti) are uniform, and do not contain any deviations from one another. However, some of the control lines 3 comprise an un-deviated section 3a and a deviated section 3b which encodes the anti-counterfeit image. The principle of the creation of the anti-counterfeit image works in the same way as in the examples above. While the raised and control lines 2, 3 have been described as being straight, it will be appreciated that the same effect can be achieved if the lines are not straight, i.e. the lines may be wavy or curved. Furthermore, while a distance D has been described as generally separating the lines, such that the composite lines 4 repeat with a general frequency of 1/D, it will be appreciated that the distance between composite lines 4 may vary.

Separate embodiments that have been described may be combined with other embodiments described, or used separately.