DOCUMENTS AND METHODS OF MANUFACTURE THEREOF

Abstract

A method of manufacturing a document of a series identical documents in content except for a respective identifier which identifies each document within the series, each identifier having at least a first indicium, the or each indicium defining a boundary; the method having the steps of: providing a substrate; applying a first background print, defining part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

Claims

1-69. (canceled)

70. A method of manufacturing a document of a series of documents which are identical in content except for a respective identifier which uniquely identifies each document within the series, each identifier comprising at least a first indicium, the or each indicium defining a boundary; the method comprising the steps of: providing a substrate; applying a first background print on the substrate, the first background print defining at least part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around at least a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

71. A method according to claim 70, wherein the substrate is at least semi-transparent.

72. A method according claim 70, further comprising applying a second background print on the substrate, wherein the first background print and the second background print are applied to opposing sides of the substrate. wherein the second background print defines said at least part of the boundary of the indicium receiving area.

73. A method according to claim 72 wherein the substrate is at least semi-transparent and wherein a portion of the second background print may be observed in transmission through the keyline from the first side of the substrate,

74. A method according to claim 70, wherein either: the first background print and the identifier are applied on the same side of the substrate; the first background print and the identifier are applied on opposing sides of the substrate; or, a first part of the respective identifier is applied on a first side of the substrate, and a second part of the respective identifier is applied on the second side of the substrate wherein the first part of the respective identifier comprises a first part of the first indicium, and the second part of the identifier comprises a second part of the first indicium and wherein the respective identifier comprises two or more indicia, and wherein the first part of the identifier and/or the second part of the identifier comprises at least one indicium of said two or more indicia.

75. A method according to claim 70, wherein the first and/or second background print extends over a lateral area which is greater than or equal to twice the lateral area over which the first indicium extends, and/or, wherein the first and/or second background print extends over at least 10% of the lateral area of the document.

76. A method according to claim 72, wherein the first indicium is visible from each side of the substrate when the document is viewed in transmission and/or reflection.

77. A method according to claim 70, wherein the keyline is visible from each side of the substrate when the document is viewed in transmission and/or reflection.

78. A method according to claim 70, wherein the keyline extends around at least 15% of the boundary of the first indicium by length.

79. A method according to claim 70, wherein the keyline visually contrasts with the first indicium and the first and/or second background print. wherein the keyline exhibits a different tint, transparency, reflectivity, or pattern than the first indicium, the first background print and/or the second background print.

80. A method according to claim 70, wherein the keyline is an unprinted region.

81. A method according to claim 70, further comprising applying a print in the indicium receiving area, wherein the print in the indicium receiving area is an indicium receiving print. and/or wherein the method further comprises applying microtext or a security pattern in the indicium receiving area.

82. A method according to claim 70, wherein the respective identifier is an alphanumeric code and/or a serial code.

83. A method according to claim 70, wherein the keyline has a width of at least 25 μm and/or wherein the keyline has a width of at most 2 mm.

84. A method according to claim 70, wherein the first background print and the identifier are applied in the same print working.

85. A method according to claim 70, wherein each identifier comprises a plurality of indicia, each indicium defining a boundary; wherein the first background print defines at least part of the boundary of a plurality of indicium receiving areas; wherein the respective identifier is applied such that each indicium is provided in an indicium receiving area of said plurality of indicium receiving areas; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and each indicium is such that a keyline extending around at least a portion of the boundary of each indicium is defined between each indicium and the indicium receiving area in which it is provided.

86. A method according to claim 70, wherein the document is a security document .

87. A method of manufacturing a series of documents which are identical in content except for a respective identifier which uniquely identifies each document within the series, each identifier comprising at least a first indicium, the or each indicium defining a boundary; the method of manufacturing each document comprising the steps of: providing a substrate; applying a first background print on the substrate, the first background print defining at least part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being provided such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around at least a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

88. A document of a series of documents which are identical in content except for a respective identifier which uniquely identifies each document within the series, each identifier comprising at least a first indicium, the or each indicium defining a boundary; the document comprising: a substrate; a first background print provided on the substrate, the first background print defining at least part of the boundary of an indicium receiving area; the respective identifier provided on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being provided such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around at least a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

89. A series of documents which are identical in content except for a respective identifier which uniquely identifies each document within the series, each identifier comprising at least a first indicium, the or each indicium defining a boundary; each document comprising: a substrate; a first background print provided on the substrate, the first background print defining at least part of the boundary of an indicium receiving area; the respective identifier provided on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being provided such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around at least a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0136] FIG. 1a shows a diagrammatic representation of a face of a document in accordance with the present invention in which only a unique identifier, background print and keylines are illustrated; FIG. 1b shows a portion of the face of the document of FIG. 1a in more detail; FIG. 1c shows a portion of the face of the document of FIGS. 1a and 1b in further detail;

[0137] FIGS. 2a to 2l show alternative cross sections in accordance with the present invention through the document shown in FIG. 1 along line X-X;

[0138] FIG. 3 shows a diagrammatic representation of a face of a further document in accordance with the present invention in which only a unique identifier, background print and keylines are illustrated;

[0139] FIGS. 4a to 4e show alternative cross sections in accordance with the present invention through the document shown in FIG. 3 along line Y-Y;

[0140] FIG. 5 shows a diagrammatic representation of a face of a further document in accordance with the present invention in which only a unique identifier, background print and keylines are illustrated;

[0141] FIG. 6a and FIG. 6b respectively show a portion of a first print working and a portion of a second print working which may be used to produce a document according to the present invention; a portion of the face of this document as seen in transmission is shown in FIG. 6c;

[0142] FIG. 7a and FIG. 7b respectively show a portion of a first print working and a portion of a second print working which may be used to produce a document according to the present invention; a portion of the face of this document as seen in transmission is shown in FIG. 7c;

[0143] FIG. 8a and FIG. 8b respectively show a portion of a first print working and a portion of a second print working which may be used to produce a document according to the present invention; a portion of the face of this document as seen in transmission is shown in FIG. 8c;

[0144] FIG. 9a shows a portion of a first print working which may be used to produce a document according to the present invention; a portion of the face of this document as seen in transmission from an angle perpendicular to the plane of the document is shown in FIG. 9b; a portion of the face of this document as seen in transmission from an oblique angle to the plane of the document is shown in FIG. 9c.

[0145] FIGS. 10a and 10b illustrate schematically web-fed printing systems for manufacturing the documents discussed above.

[0146] FIGS. 11a, 11b and 11c illustrate schematically further web-fed printing systems for manufacturing the documents discussed above.

DETAILED DESCRIPTION

[0147] FIG. 1 a shows a document 10 which is provided with a background print 12 and an identifier in accordance with the present invention. The document 10 is part of a series of documents 10 which are identical in content except for the identifier, which is unique to the specific document 10 shown.

[0148] The identifier comprises five laterally spaced indicia 14. These indicia 14 are alphanumeric and, as will be seen from the figure, the identifier applied to the illustrated document reads “0123Z”.

[0149] Each of the indicia 14 are surrounded by a keyline 16 which extends around the entire boundary of the respective indicium 14. The keylines 16 separate the indicia 14 from the first background print 12 and appears juxtaposed between the background print 12 and the indicia 14. Notably, the indicium “0” also has an internal void, and a keyline 16 extending around the boundary of this internal void. However, this is not essential and in alternative documents an internal void within an indicium 14 may not be provided with a keyline 16.

[0150] The portion of document 10 is shown in more detail in FIG. 1b, and even closer in FIG. 1c. As shown, the background print 12 defines the boundaries 11a of five laterally spaced indicium receiving areas 11, corresponding to the five indicia 14. Each indicium 14 is provided within a corresponding indicium receiving area 11. As will be seen the boundary 11a of each indicium receiving area 11 is substantially parallel to the boundary 14a of the respective indicium 14, and together the boundary 11 a of each indicium receiving area 11 and the boundary 14a of the respective indicium 14 define a keyline 16 (i.e. a boundary or contour line) of substantially constant thickness which extends around the entire boundary 14a of the respective indicium 14. Thus the keylines 16 are formed through the juxtaposition or contrast between the first background print 12 and the indicia 14.

[0151] No details of the background print 12 are illustrated in FIGS. 1a, 1b and 1c. However, substantially any image, symbols, text or graphics may be provided as part of the background print 12 to enable the document 10 to perform its function. For instance, if the document 10 were a banknote the background print 10 may include the denomination of the banknote, the name of the bank or body issuing the banknote and a variety of further security devices. As shown, the background print is hatched and these hatching do not extend over the entire extent of the document. However, as will be readily appreciated, the background print 12 can extend over substantially any proportion of the lateral area of the document 10 so long as it defines the indicium receiving areas 11 as discussed above. Furthermore, it will be appreciated that the background print of a document, such as the background print 12 shown in FIGS. 1a, 1b and 1c, may be formed of multiple prints or print workings that are applied over one another.

[0152] In a series of the documents 10 shown in FIG. 1 each document 10 will be provided with a unique identifier. Therefore, at least one indicia 14 forming the identifier will be changed between adjacent documents 10 in the series. For instance, a consecutive or adjacent document to the document 10 shown in FIG. 1 may be provided with an identifier reading “0124Z”, “0123k”, or any other unique identifier. As will be appreciated, the boundaries of the indicia 14 in an identifier applied to any given document 10 in the series will be different from the boundary of the indicia 14 in the identifiers applied to the remaining documents 10 in the series.

[0153] Since the boundary 14a of at least one indicium 14 changes between adjacent documents 10 in the series, the boundary 11a or boundaries 11a of the corresponding indicium receiving area(s) 11 must also change between the adjacent documents 10 to maintain keylines 16 which accurately follow the boundaries 14a of the indicia 14. Therefore, although the content of the documents 10 does not vary between individual documents 10, the extent of the indicium receiving areas 11 will vary, and as such the first background print 12 (which defines the boundaries 11a of the indicium receiving areas 11) must also be varied between documents. Therefore the difficulty of reproducing documents 10 in the series is increased.

[0154] Although all of the indicia 14 shown in FIGS. 1a, 1b and 1c are provided with keylines 16 in alternative embodiments an indicium receiving area 11 and keyline 16 may only be defined around a single indicium 14 of the identifier (or even only around a portion of a single indicium 14 of the identifier). In such documents 10, there is no need to vary the background print 12 unless the indicium 14 provided with the keyline 16 is changed (i.e. a boundary of the indicium 14 provided with a keyline 16 changes).

[0155] For instance, if only the first indicium 14 of a five digit identifier (e.g. the “0” of the identifier “0123Z” shown in FIG. 1) is surrounded by a indicium receiving area 11 (i.e. a single keyline 16 is defined around the “0” by the juxtaposition of the indicia “0” and the background print 12), it is only necessary to vary the background print 12 and the boundary 11a of the indicium receiving area 11 defined by the background print 12 when the first indicium 14 changes (e.g. when the background print 12 is changed from “0123Z” to “1123Z”, but not from “0123Z” to “0123A”).

[0156] Nevertheless, even if a keyline 16 is provided only to a single indicia 14 or a subset of the indicia 14 in an identifier, the number of background prints 12 which must be printed is increased relative to a series of documents 10 without a keyline 16. Furthermore, in these embodiments there is still a requirement to accurately register the background print 12 and each indicium receiving area 11 to the indicia 14 to correctly define the keyline(s) 16. Each of these requirements increases the difficulty of imitating the series of documents 10 for a counterfeiter.

[0157] The document 10 shown in FIG. 1 (which as discussed above includes keylines 16 formed by the juxtaposition of the indicia 14 and the first background print 12) may be created by a wide variety of document structures. Examples of these structures will now be discussed with reference to FIGS. 2a to 2l which show alternative cross sections of the document 10 along line X-X (as shown in FIG. 1a).

[0158] In FIGS. 2a to 2l the documents 10 each comprise: a substrate 18 with opposed first and second sides 18a, 18b, a first background print 12 applied to a first side 18a of the substrate 18; an indicium receiving area 11, the boundary 11a of which is defined by the first background print 12; and an indicium 14, the number “1”, as shown in FIGS. 1a and 1b.

[0159] The lateral extent and relative lateral positioning of the first background print 12, the indicium receiving area 11 and the indicium 14 are identical in each of the cross sections of FIGS. 2a to 2l. However, different appearances and effects of document 10 may be achieved through the provision of further features and changes to the position of the features relative to the substrate 18 (i.e. in a direction normal to the surfaces 18a, 18b of the substrate 18 and the document 10, and perpendicular to the lateral directions parallel to the surfaces 18a, 18b of the substrate 18 and the document 10), as discussed below.

[0160] FIG. 2a shows a portion of a document 10 in cross section. The document 10 comprises a substrate 18 with opposed first and second sides 18a, 18b. On a first side 18a of the substrate 18 are provided a background print 12 and the indicium “1” of the identifier “0123Z” shown in FIGS. 1a and 1b. The boundary of the background print 12 defines the boundary 11a of an indicium receiving area 11. As such, the boundary of the background print 12 and the boundary 11a of the indicium receiving area are congruent and have the same lateral position by definition. The indicium 14 is provided in (i.e. received within, positioned within) the indicium receiving area 11 such that the indicium receiving area 11 entirely surrounds the indicium 14. The indicium receiving area is unprinted between the boundary of the background print 12 and the boundary 11 a of the indicium receiving area 11 on both sides 18a, 18b of the substrate 18.

[0161] Therefore, when viewed from the first side 18a of the substrate 18, the indicium 14 will be seen (i.e. observed) against the first background print 12 and surrounded by an unprinted keyline 16 extending around its boundary. The unprinted keyline 16 may be easily visually distinguished from the printed indicium 14 and background print 12, especially if the indicium 14 and background print 12 are printed with tinted or at least semi-opaque inks. If the substrate 18 is at least semi-transparent the background print 12, indicium 14 and keyline 16 may also be observed in transmission from the second side of the substrate 18, and where the substrate is substantially transparent the keyline 16 is defined by a transparent window through the document 10.

[0162] Since the keyline 16 may be easily distinguished from the indicium 14 and the background print 12, any errors in registration between the background print 12 and indicium 14 (as might be introduced in a counterfeiting process) will be easily observed.

[0163] The document 10 of FIG. 2a may be manufactured by printing the background print 12 and the indicium 14 in separate steps—i.e. where the background print 12 and the indicium 14 are sequentially applied in separate first and second print workings. Alternatively, the background print 12 and the indicium 14 may be applied simultaneously in a single, combined print working.

[0164] FIG. 2b shows an alternative structure for the document 10 of FIG. 1 which again exhibits keylines 16 extending around (i.e. surrounding) indicia 14, as shown in FIG. 1.

[0165] Unlike in FIG. 2a the keyline 16 of FIG. 2b is not unprinted and instead the document 10 is provided with an indicium receiving print 20 on the first side 18a of the substrate 18. The indicium receiving print 20 is provided between the boundary 14a of the indicium 14 and the boundary of the indicium receiving area 11a (i.e. between the indicium 14 and the background print 12) and therefore forms the keyline 16 extending around the indicium 14. In other words the indicium receiving print 20 is provided to the regions of the indicium receiving area 11 in which the indicium 14 is not located, so as to form a printed keyline 16. Thus, the keyline 16 will exhibit the appearance of the indicium receiving print 20. The indicium receiving print 20 may differ from the indicium 14 and the background print 12 in appearance by (for instance) colour, tint, transparency, reflectivity, pattern, texture, thickness and/or another observable property. Therefore, the printed keyline 16 may be easily compared to the indicium 14 and background print 12.

[0166] In this example it will be seen that the boundary 11a of the indicium receiving region 11 may be defined by variations in the inks or other properties between the indicium receiving area 11 and the first background pint 12, and/or the boundary 14a of the indicia 14 may be defined by the variation in inks or other properties between the indicia 14 and the indicium receiving area 11.

[0167] For instance, the indicium receiving print 20 may be applied in the same print working with the background print 12 and/or the indicium 14—e.g. the three components may be different parts of a continuous printed layer applied across the first side 18a of the substrate 18, each part of which has a different ink composition. Alternatively, these features may be applied in separate print workings.

[0168] FIG. 2c shows a document 10 which comprises a background print 12 and an indicium 14 provided to the first side 18a of a substrate 18. The background print 12 defines an indicium receiving area 11. An indicium receiving print 20 is provided within the indicium receiving area 11 on the first side 18a of the substrate 18 and extends across the whole of the indicium receiving area 11. The indicium 14 is positioned laterally within the indicium receiving area 11 defined by the background print 12 and over the indicium receiving print 20 relative to the substrate 18 (i.e. such that the printed keyline region 20 is provided between the indicium 14 and the substrate 18).

[0169] Assuming the indicia 14 of the document 10 is substantially opaque (e.g. opaque to light in the visible spectrum), when viewed from the first side 18a of the substrate 18 the document 10 of FIG. 2c will exhibit a similar appearance to the document 10 of FIG. 2b—i.e. the substantially opaque indicium 14 will be observed surrounded by a printed keyline 16 (formed by the portion of the indicium receiving print 20 positioned laterally between the indicium 14 and the boundary of the indicium receiving area 11). The indicium 14 and the keyline 16 (which follows the boundary of the indicium 14, as shown in FIGS. 1a, 1b and 1c) will be seen against the background print 12. Additionally, if the indicium 14 of FIG. 2c is at least semi-transparent, the printed keyline region 20 may be observed through the indicia 14 when viewed from the first side 18a of the substrate.

[0170] From the second side 18a of the substrate 18, the indicium 14 will be seen in transmission through the indicium receiving print 20 if the indicium receiving print 20 and the substrate 18 are at least semi-transparent in combination. Alternatively, the indicium 14 may not be visible from the second side 18b of the substrate 18 in the event that the indicium receiving print 20 and the substrate 18 are substantially opaque.

[0171] FIG. 2d shows a further example of a document 10 which exhibits keylines 16 extending around an indicium 14. The document 10 comprises a substrate 18 with opposed first and second sides 18a, 18b, and which is at least semi-transparent over at least the indicium receiving area 11. On the first side 18a of the substrate 18 is provided a first background print 12, whereas the indicium 14 is provided to the opposing second side 18b of the substrate 18.

[0172] The boundaries of the background print 12 define the boundaries 11a of an indicium receiving area 11 which, as shown, is unprinted on the first side 18a of the substrate. The indicium 14 is located laterally (i.e. in the directions of the plane of the document 10) within the indicium receiving area 11, as defined by the first background print 12. Therefore, an unprinted keyline 16 is defined around indicium 14 by the juxtaposition of the first background print 12 and the indicia 14, the keyline 16 extending between the boundary 14a of the indicia and the boundary of the indicium receiving area 11.

[0173] When viewed from either side 18a, 18b of the at least semi-transparent substrate 18 the indicium 14 will be seen against the background print 12, such that the background print 12 and indicium 14 are separated by the unprinted and substantially transparent keyline 16. This unprinted keyline 16 will exhibit the appearance of the substrate, and where the substrate is substantially transparent will form a transparent window which is particularly striking and readily observed by a human or machine observer, such that the document 10 can be quickly and easily authenticated. Preferably the indicium 14 and the background print 12 are configured such that the unprinted keyline 16 will be visible to a naked or unaided human eye such that it may be seen by a human observer without the need for additional equipment (however, this is not essential).

[0174] The indicium 14 and background print 12 may be applied as separate print workings to the opposing sides 18a, 18b of the substrate 18. These print workings may be applied simultaneously or sequentially as part of either a web-fed or sheet-fed process.

[0175] FIGS. 2e to 2h show further documents 10 which comprise two background prints 12, 22 applied respectively to the two opposing sides 18a, 18b of a substrate 18. These documents 10 may exhibit different appearances when viewed from either side 18a, 18b of the substrate 18 if the two background prints provide different appearances. These effects are particularly advantageous where the substrate 18 is transparent or semi-transparent across at least the indicium receiving areas 11 such that he indicium 14 can be observed from either side 18a, 18b of the substrate 18. In particular, the substrate 18 is preferably substantially transparent across its entire width.

[0176] FIG. 2e shows a document 10 in which a first background print 12 is provided to a first side 18a of the substrate 18 and a second background print 22 is provided to the second side 18b of the substrate 18. A boundary of each of the first and second background prints 12, 22 defines the boundary of the the indicium receiving area 11 (i.e. the boundaries of the background prints 12, 22 are congruent around the boundary of the indicium receiving area 11). Therefore, the boundaries of the first and second background prints 12, 22 together define the boundary 11a of an indicium receiving area 11. In some embodiments the first and second background prints 12, 22 may have the same extents, but this is not essential.

[0177] An indicium 14 is provided on the second side 18b of the substrate 18 such that it is positioned laterally (i.e. in the plane of the document 10) within the indicium receiving area 11. Therefore, the indicium 14 is provided entirely within the indicium receiving area 11, such that the juxtaposition of the first and second background prints 12, 22 defines an unprinted keyline 16 extending between the boundary 14a of the indicia 14 and the boundary 11a of the indicium receiving area 11.

[0178] Where the substrate 18 is substantially transparent across at least the indicium receiving area 11 (as defined by the first and second background prints 12, 22), the indicium 14 will be observed surrounded by an unprinted keyline 16 when viewed from each side 18a, 18b of the substrate 18. Specifically, from the first side 18a of the substrate, the indicium 14 and the first background print 12 will be seen, separated by the visually contrasting unprinted (and thereby substantially transparent) keyline 16. In contrast, from the second side of the substrate 18b, the indicium 14 and the second background print 22 will be observed separated by the visually contrasting unprinted (and substantially transparent) keyline 16.

[0179] Alternatively, if the substrate 18 is formed of a substantially opaque material (e.g. paper) or coated with one or more opacifying layers (not shown) such that it is substantially opaque, the indicium 14 will not be visible from the first side 18a of the substrate 18 in reflection.

[0180] In this case, from the second side 18b of the substrate 18, the indicium 14 will be seen surrounded by a keyline 16 which exhibits the appearance of the unprinted substrate 18 (including any layers applied to the surface of the substrate 18) against the second background print 22. In contrast, from the first side 18a of the substrate 18 in reflection the first background print 22 will be observed with an unprinted indicium receiving area 11 defined therein.

[0181] During manufacture of the document 10 of FIG. 2e the first background print may be applied to the first side 18a of the substrate 18 as a first print working, whereas the indicium 14 and the second background print 22 may be applied to the second side 18b of the substrate 18 together in a second print working.

[0182] FIG. 2f shows a document 10 with two background prints 12, 22 where only the first background print 12 defines the boundary 11a of a indicium receiving area 11. Specifically, the boundary of the first background print 12 defines the boundary 11a of the indicium receiving area 11. In contrast, the second background print 22 extends continuously across the second side 18b of the substrate 18 without interruption. The indicium 14 is provided on the first side 18a of the substrate 18 within the indicium receiving area 11, as defined by the first background print 12.

[0183] When viewing the document 10 from the first side 18a of the substrate 18, the indicium 14 and the first background print 12 are observed separated by a keyline 16 (which, as shown in FIGS. 1a, 1b and 1c, follows the contours of the indicium 14). The appearance of the keyline 16 will vary depending on the opacity of the substrate 18. If the substrate 18 is transparent or translucent a viewer may observe the second background print 22 in the keyline 16 through the substrate 18. This effect will be particularly strong when viewing the document 10 in transmission. Alternatively, if the substrate 18 is substantially opaque an observer will see the substrate 18 in the keyline 16.

[0184] If the substrate 18 and second background print 22 are substantially opaque in combination the indicium 14 will not be visible from the second side 18b of the substrate. Otherwise the indicium 14 may be observed through the substrate 18 and second background print 22 from the second side 18b of the substrate.

[0185] FIG. 2g shows a modification of the document 10 shown in FIG. 2e wherein the keyline 16 is printed on the first side 18a of the substrate 18.

[0186] On the first side 18a of the substrate 18 there is provided a first background print 12 and an indicium receiving print 20 in a indicium receiving area 11 defined by the first background print 12. The indicium 14 is provided laterally within the indicium receiving area 11 on the second side 18b of the substrate 18. The indicium receiving area is otherwise unprinted on the second side 18b of the substrate 18. However, in contrast to FIG. 2e, the document 10 of FIG. 2f further comprises an indicium receiving print 20 applied to the first side 18a of the substrate 18 between the boundary 11a of the indicium receiving area 11 and the boundary 14a of the indicium 14.

[0187] Assuming the substrate 18 is substantially transparent, the document 10 shown in FIG. 2g will exhibit a similar appearance to the document 10 of FIG. 2b when viewed from the first side 18a of the substrate 18. Specifically the document 10 exhibits an indicium 14 surrounded by a printed keyline 16 (which exhibits the appearance of indicium receiving print 20) and seen against the first background print 12. In contrast, from the second side 18b of the substrate 18 (i.e. the reverse side) the indicium 14 will be seen surrounded by the printed keyline 16 against the second background print 22.

[0188] Therefore, the document 10 may exhibit different appearances from either side 18a, 18b of the substrate 18. The appearance of the two sides may therefore be decoupled assuming that the background prints 12, 22 are substantially opaque. On the other hand, if the first background print 12 and second background print 22 are at least semi-transparent the background prints 12, 22 may be seen superimposed upon one another in transmission from either side 18a, 18b of the substrate 18.

[0189] This example is very difficult to counterfeit because of the need to accurately register the indicium 14 within the lateral area defined within the indicium receiving print 20 on the opposing side of the substrate 18.

[0190] FIG. 2h is a further modification of the structure shown in FIG. 2e. However, in this case the document 10 of FIG. 2h exhibits a similar appearance as the document 10 of FIG. 2c.

[0191] The extents and positions of the indicia 14, first background print 12 and the second background print 22 are identical to those in FIGS. 2e and 2g. The document 10 further comprises an additional print 20 provided on the first side 18a of the substrate (as in FIG. 2g) within the indicium receiving area 11. The additional print 20 extends fully and continuously across the indicium receiving area 11 (the boundary 11a of which is defined by the background prints 12, 22).

[0192] From the first side 18a of the substrate 18, the indicium 14 may be observed through the additional print 20 within the indicium receiving area 11 if the additional print 20 and the substrate 18 in the region of the indicium receiving area 11 are at least semi-transparent in combination. In this situation the indicium 14 will be observed through the indicium receiving print 20 such that they appear superimposed. In addition, the indicium 14 and will be separated from the first background print 12 by a printed keyline 16 which exhibits the appearance of the print 20 and is laterally positioned between the indicium 14 and the first background print 12. Where the print 20 within the indicium receiving area 11 and the substrate 18 are substantially opaque in combination the indicium 14 will not be observed from the first side 18a of the substrate 18.

[0193] Regardless of the opacity of the indicium receiving print 20 and the substrate 18, from the second side 18b of the substrate 18 the document 10 of FIG. 2h will exhibit a similar appearance as the document 10 of FIG. 2g—the indicium 14 and the second background print 22 will be observed separated by a keyline 16 which surrounds the indicium 14 and exhibits the appearance of the print 20 within the indicium receiving area 11.

[0194] FIGS. 2i to 2l show further examples of documents 10 which exhibit indicia 14 surrounded by keylines 16. However, in each case the indicia 14 is split into two parts 14b, 14c. The first part 14b of the indicium 14 is provided to the first side 18a of the substrate 18, whilst the second part 14c of the indicium 14 is provided to the second side 18b of the substrate 18.

[0195] In each case the substrate 18 is substantially visually transparent across at least the indicium receiving area 11, and as such the two parts 14b and 14c may be seen in combination from either side of the document 10 in transmission. Therefore, as will be appreciated the documents 10 of FIGS. 2i and 2j will appear similar to the documents 10 shown in FIGS. 2a and 2e respectively when viewed in transmission and the documents 10 of FIGS. 2k and 21 will appear similar to the documents 10 shown in FIGS. 2b and 2g respectively when viewed in transmission (assuming the documents 10 of FIGS. 2a, 2e, 2b and 2g have substantially transparent substrates).

[0196] However, the documents 10 of FIGS. 2i, 2j, 2k and 2l may exhibit different appearances to documents 2a, 2e, 2b and 2g respectively when viewed in reflection, since only the part 14b, 14c of the indicium 14 applied to the respective side 18a, 18b of the substrate 18 may be observed (depending on the reflectivity of the substrate 18).

[0197] In FIGS. 2i and 2j the keyline 16 is unprinted and substantially transparent. In FIGS. 2k and 21 the documents 10 are provided with an indicium receiving print 20 which extends between the boundary 14a of the indicium 14 and the boundary 11a of the indicium receiving area 11. In this case the keyline 16 therefore exhibits the appearance of the indicium receiving print 20 and may be either transparent or opaque depending on the properties of the indicium receiving print 20.

[0198] The documents 10 of FIGS. 2i, 2j, 2h and 21 are significantly more difficult for an unauthorised reproducer to copy than the documents 10 of FIGS. 2a and 2e since it is very difficult to accurately register the different parts 14b, 14c of the indicium 14 together since they are provided to opposing sides of the substrate 18 (i.e. they are applied in separate print workings). Therefore, these documents 10 offer increased security.

[0199] Any of the documents 10 discussed above with reference to FIGS. 2a to 21 may comprise a plurality of further workings or layers extending across whole or part of the document 10, and on either or both sides 18a, 18b of the substrate 18. These may include additional print workings, opacifying layers protective layers, adhesive layers or anti-static conductive layers. These workings and layers may be provided within the substrate 18, or be applied or printed on the substrate 18 such that they overlie or underlie one or more of the background prints 12, 22, indicium 14 and printed keyline regions 20 relative to the substrate 18.

[0200] In summary, it will be appreciated that documents 10 with identifiers in which the indicia 14 of an identifier are wholly surrounded by a keyline 16 offers increased security. However, this is not essential and in further documents a keyline may be provided which only extends around a portion of an indicium. Examples of such documents are shown in FIGS. 3, 4 and 5.

[0201] FIG. 3 shows a face of a document 30 in accordance with the present invention provided with a background print 32 and an identifier. In line with FIG. 1 the identifier comprises five laterally spaced indicia 34. These indicia 34 are again alphanumeric and read “01231”. As shown, the upper portion of each indicium 34—approximately half of each indicium 34—is surrounded by a keyline 26.

[0202] Unlike in FIG. 1 the first background print 32 of the document 30 in FIG. 3 does not define a corresponding number of indicium receiving areas, such that each indicium 34 is provided in a respective indicium receiving area. Rather, the background print 32 defines the boundary 31a of a single indicium receiving area 31 in which all of the indicia are provided. As shown, the indicium receiving area 31 extends across the entire width of the document 30 and the indicia 14 are provided fully within the indicium receiving region 31. As will be seen from the figure, the indicium receiving area 31 extends between a boundary 31a defined by the first background print 32 and the external boundary or extreme extents of the document 30.

[0203] The part of the boundary 31a of the indicium receiving area 31 defined by the first background print 32 extends around the top or upper portion (approximately the top half) of the boundary 34a of each indicium 34. Therefore, a keyline 36 which extends around the upper portion of the boundary of each indicium 34 and the boundary 31a of the indicium receiving area 31 is formed by the juxtaposition of the first background print 32 and the indicium 34.

[0204] The boundary 31a of the indicium receiving area 31 defined by the first background print 32 is approximately parallel to the boundary of the indicia 34. Therefore, the keylines 36 are of substantially the same width at all points around the upper portion of each indicium 34. In addition the width of the keylines 36 is substantially the same width around all of the indicia 34. This appearance requires highly accurate registration (i.e. relative positioning) between the background pint 32, indicia 34 and the indicium receiving area 31.

[0205] Approximately half of each indicium 34 is surrounded by a keyline 36—i.e. a keyline 36 extends around approximately 50% of the boundary of each indicium 34 by length (although the specific figure will vary dependent on the shape and distribution of each indicium 34).

[0206] The details of the appearance of the background print 32 are not shown in FIG. 3. However, substantially any image, symbols, text or graphics may be provided as part of the background print 32 to enable the document 10 to perform its function.

[0207] As discussed with reference to FIG. 1, as the unique identifier is varied between documents 30 in the series, the indicia 34 forming the identifier will change and therefore the boundaries 34a of the indicia 34 will also change between documents 30. Hence, in order to correctly generate keylines 36 surrounding the indicia 34 as shown in FIG. 3, the indicia 34 and the background pint 32 (which defines the indicium receiving area 31) must be varied between documents 30 to achieve the keylines. This variation is not easy for an unauthorised reproducer to achieve using conventional printing technologies for producing large numbers of uniquely identified documents.

[0208] Exemplary cross sections of a document 30 along line Y-Y which may be used to produce this appearance will be discussed below in reference to FIGS. 4a to 4e.

[0209] In each cross section the indicium 34 (the figure “1”, as shown in FIG. 3), the first background print 32, the indicium receiving area 31 and keyline 36 (as defined by the juxtaposition of the indicium 34 and the first background print 32) have the same extents in the plane of the document 30 (i.e. the same lateral extents).

[0210] The document 30 of FIG. 4a broadly corresponds in structure and manufacturing methods to the document 10 of FIG. 2a. The first background print 32 and the indicium 34 are provided on the first side 38a of a substrate 38. As shown, the portion of the indicium receiving area 31 which separates the first background print 32 and the indicium 34 is unprinted on both sides 18a, 18b of the substrate 18, and part of the boundary 31a of the indicium receiving area 31 is defined by (and therefore coincident with) the boundary of the first background print 32. The remaining boundary of the indicium receiving area 31 is defined by the boundary or outer extent of the document 30. The indicium 34 is provided within the indicium receiving area 31 such that a keyline 36 is defined between the boundary 34a of the indicium 34 and the boundary 31a of the indicium receiving area 31 (as defined by the first background print 32). The background print 32b and the indicium 14 may be applied in separate print workings, in a single print working or in any other suitable method.

[0211] FIG. 4b shows an alternative structure for a document 30 with the appearance of FIG. 3 in cross section along line Y-Y. This document 30 and shares a similar structure to the document 10 shown in FIG. 2b. In addition to the features of the document 30 shown in FIG. 4a, this document 30 further comprises an indicium receiving print 40 (not shown in FIG. 3) which is provided between the upper portion of the boundary 34a of the indicium and the boundary 31a of the indicium receiving area 31 such that the indicium receiving print 40 fills and extends across the keyline 36.

[0212] Therefore when the document 30 is observed the differences in properties of the first background print 32, the indicium 34, the keyline 36 and the indicium receiving print 40 which extend around the upper portion of the indicium 34 and the unprinted substrate 38 which surrounds the bottom portion of the indicium 34 may be compared. Reproducing the appearance of each of these regions and printed features is not easy for a would-be counterfeiter, and any unexpected variations in appearance (e.g. colour, tint, transparency, reflectivity, pattern, texture and/or another observable property) may be easily identified by an authenticator. Therefore the security of the document 30 is increased.

[0213] FIG. 4c shows a modification of the structure shown in FIG. 4b wherein the indicium receiving print 40 (not shown in FIG. 3) extends around the entire boundary 34a of the indicia 34 with substantially the same width at each point around the boundary 34a of the indicia 34.

[0214] Therefore, as will be appreciated a printed keyline 36 with the appearance of the indicium receiving print 40 extends around the entirety of the boundary 34a of the indicia 34. The keyline 36 defined between the boundary 34a of the indicia 34 and the external boundary of the indicium receiving print 40. Around the upper portion of the indicia, the external boundary of the indicium receiving print 40 is coincident with the part of the boundary 31a of the indicium receiving area 31 defined by the first background print 32.

[0215] Again, when the document 30 is observed, differences in properties and appearances of the first background print 32, indicium 34, and the indicium receiving print 40 and the unprinted substrate 38 within the indicium receiving area 31 may be easily compared. Since the indicium receiving print 40 extends around the entirety of the indicium 34 it is more difficult to register the indicium 34 and the printed keyline region 40 relative to one another. Therefore the security of the document 30 is increased relative to conventional documents distinguished using identifiers as the document 30 is more difficult for a would-be counterfeiter to imitate.

[0216] FIG. 4d shows a document 30 where a continuous printed layer comprising a first background print 32 and an indicium receiving print 40 is provided across the entirety of the first surface 38a of a substrate 38. The boundary between the first background print 32 and the indicium receiving print 40 defines part of the boundary 31a of an indicium receiving area 31 (i.e. the first background print 32 defines part of the boundary 31a of the indicium receiving area 31). This boundary 31a may be defined by any variation in the properties of the background print 32 and the indicium receiving print 40. For instance, the first background print 32 and the indicium receiving print 40 may exhibit different appearances and exhibit different colours or tints, patterns, textures or any other suitable property. The indicium 34 is provided in the indicium receiving area 31, in contact with and over the indicium receiving print 40 relative to the first side 38a of the substrate.

[0217] The first background print 32 and the indicium receiving print 40 are preferably applied as a single print working, and the indicia 34 is overprinted in a subsequent print working. However, this is not essential.

[0218] Assuming the substrate 38 and the indicium receiving print 40 are at least semi-transparent in combination, when the document 30 is viewed from the first side 38a of the substrate 38 the indicia will be observed surrounded by the indicium receiving print 40, whereas when the document 30 is viewed from the second side 38b of the substrate 38 the indicium 34 will be viewed in transmission through the an indicium receiving print 40 (such that the indicium 34 and the indicium receiving print 40 appear superimposed). In contrast, if the substrate 38 and the indicium receiving print 40 are substantially opaque the indicium 34 will only be seen from the first side 38a of the substrate 38 surrounded by the indicium receiving print 40. In each case the indicium 34 will be seen partially surrounded by a keyline 36 formed by the indicium receiving print 40 extending around an upper portion of the indicium 34 between the boundary 31a of the indicium receiving area 31 and the boundary 34a of the indicium 34.

[0219] FIG. 4e shows a document 30 which exhibits an alternative “double-sided” appearance, wherein the appearance of the document 30 is different when viewed from the first side 38a of the substrate 38 and the second side 38b of the substrate 38. As will be seen, the document 30 shown in FIG. 4e is analogous to the document 10 of FIG. 2e.

[0220] In FIG. 4e the document 30 is provided with a first background print 32 on a first side 38a of an at least semi-transparent substrate 38. The boundary of the first background print 32 defines part of the boundary 31a of a first indicium receiving area 31 with the same extent as the indicium receiving areas discussed above with reference to FIG. 3 and FIGS. 4a to 4d. Specifically, the first indicium receiving area extends between a boundary 31a defined by the first background print and the external boundary 30a of the document 30 itself.

[0221] The first indicium receiving area 31 is unprinted on the first side 38a of the substrate 38.

[0222] On the second side 38b of the substrate 38 are provided a second background print 42 and the indicium 34. The boundary of the second background print 42 wholly defines the boundary 41a of second indicium receiving area 41. As will be seen the second indicium receiving area 41 extends over a part of the lateral extent of the first indicium receiving area 31.

[0223] The indicium 34 is arranged laterally such that it is provided in both the first indicium receiving area 31 and second indicium receiving area 41. A keyline 36 is defined between the boundary 31a of the first indicium receiving area 31 and the boundary 34a of the indicium 34 and extends around the upper portion of the indicium 34 (as shown in FIG. 3). A further keyline 36 (not shown in FIG. 3) is defined between the boundary 41a of the second indicium receiving area 41 and the boundary 34a of the indicium 34 and extends around the whole boundary of the indicium 34.

[0224] When viewed from the second side 38a of the substrate 38 the document 30 will exhibit the same appearance to an observer as the document 10 of FIG. 2e—an indicium 34 printed against a second background print 42 such that the indicium 34 and second background print 42 separated by an unprinted keyline 46. This is because the boundary 31a of the first indicium receiving area 31 and the boundary 41a of the second indicium receiving area 41 are coincident around the upper portion of the indicium 34 (shown to the left of FIG. 4e) such that the keyline 36 appears continuous around the whole of the boundary 34a of the indicium 34.

[0225] However, assuming the substrate 38 is at least semi-transparent the document 30 will provide a different appearance from the first side 38a of the substrate.

[0226] Specifically, when viewed from the first side 38a of the substrate 38 the document 30 will exhibit an indicium 34 entirely surrounded by an unprinted keyline 36. The keyline 36 will separate the upper portion of the indicia 34 from the first background print 32 (as shown in FIG. 3), and the lower portion of the indicia 34 from the second background print 42 (not shown in FIG. 3).

[0227] Therefore, the appearance of the document 30 will be different when viewed from either side 38a, 38b of the substrate 38 (i.e. from either side of the document 30 in use). In this case an observer will be able to inspect the document 30 in order to compare the properties and appearances of each of the printed and unprinted features from either side.

[0228] The documents 30 shown in FIGS. 4a to 4e may be further modified to create more complicated visual effects using any of the structures and techniques discussed with reference to FIGS. 1 and 2a to 21. For instance, the indicia 34 may be split into two parts which are printed on opposing sides of the documents 30, as in FIGS. 2i to 21. Alternatively, one or more indicium receiving prints may be provided under or around the indicium 34 in (for instance) FIG. 4e such that these prints appear in the keyline 36 extending around at least part of the indicium 34.

[0229] FIG. 5 illustrates a further exemplary document 50 that comprises many similar features to the documents 10, 30 of FIGS. 1 and 3. This document 50 may be constructed using any of the techniques discussed above. As seen from the figure, the document 50 is provided with an identifier comprising five alphanumeric indicia 54 reading “0123Z”

[0230] As with the document 30 of FIG. 3, the document 50 of FIG. 5 comprises a background print 52 which here defines the whole of the boundary of an indicium receiving area 51. The indicia 54 are provided within the indicium receiving area 51 such that they are surrounded in a lateral direction (i.e. in the plane of the document 50) by the boundary of the indicium receiving area 51.

[0231] However, the document 50 of FIG. 5 differs from the documents 10, 30 of FIGS. 1a and 3 in two significant aspects.

[0232] Firstly, the keyline 56 generated by the juxtaposition of the background print 52 and indicia 54 only extends around a portion of the indicia 54 (unlike in the document 10 shown in FIGS. 1a, 1b and 1c). As in the embodiments discussed above, a keyline 56 is defined between the boundary of the indicium receiving area 51 (as defined by the background print 52) and the boundary of each indicium 54 rather than approximately the upper half of each indicium 54 as shown in FIG. 3. However, the boundary of the indicium receiving area 51 only follows a contour of the boundary of each indicium 54 at an uppermost portion of the indicia 54. For instance, it will be seen that the keyline 56 which extends around the indicium “Z” only extends as a border around the top and sides of the upper bar (i.e. upper horizontal stroke) of the letter “Z”.

[0233] The proportion of each indicium 54 where a keyline 56 extends adjacent to the boundary of the indicia 54 varies dependent on the shape of the indicia 54. In the case of the “2”, “3”, and “Z” indicia 54 a keyline 56 extends around approximately 20% of the boundary of each indicium 54 by length. In the case of the indicium “1” a keyline 56 extends around approximately 40% of the indicium 54. A keyline 56 extends around approximately 50% of the external boundary of the indicium “0”. No keyline 56 extends around the internal boundary of the “0” (i.e. around the boundary of the negative space within the “0).

[0234] Secondly, the lateral extent of the indicium receiving area 51 shown in FIG. 5 is reduced in size relative to the document 30 of FIG. 3. Instead of extending across the entire width of the document 50, the indicium receiving area 51 of FIG. 5 covers less than 10% of the area of the document 50. Unlike the document 30 of FIG. 3, the indicium receiving area 51 shown in FIG. 5 does not extend to the boundaries of the document 50. In other words, the boundary of the indicium receiving areas 51 is wholly defined by the background print 52. As discussed with reference to FIGS. 4a to 4e the indicium receiving area 51 may be printed or unprinted.

[0235] It will be appreciated that the additional features of the indicium receiving area 51 discussed with reference to FIG. 5 are not intrinsically related to each other and may be combined in with the features of the alternative embodiments of documents discussed above in any combination.

[0236] Furthermore, it will be appreciated that the different structures shown in the exemplary cross sections of FIGS. 2a to 21 and FIGS. 4a to 4e (or any modifications of the structures) may be used to create keylines around different indicia provided in the same identifier or indicia provided to the same document. For instance, where an identifier comprises two or more indicia, one or more indicia may be surrounded by a keyline formed using the structure shown in FIG. 2a, whilst one or more one or more indicia of the same identifier may be provided according to the cross section of FIG. 4b, and so one.

[0237] FIGS. 6, 7, 8, and 9 show portions of further documents 60, 70, 80, 90 to which an identifier 69, 79, 89, 99 has been applied. The documents 60, 70, 80, 90 are part of a wider series of documents each provided with a unique identifier 69, 79, 89, 99.

[0238] These documents 60, 70, 80, 90 illustrate that a wide variety of identifiers 69, 79, 89, 99 may be used with the present invention. In FIG. 6 an alphanumeric serial code 69 is printed vertically and horizontally on the document 60. The serial code reads “A/I 000000”. In addition each indicium 64 in the identifier 69 is increased in size relative to the preceding indicia 64. In FIG. 7 the identifier 79 is a circular code. In this code a string or series of digits are represented by the arcs in a series of segments surrounding a circle at the centre of the identifier 79 (marked ‘AC’). The value of each digit in the string is encoded by the number of arcs in the corresponding segment and the distance of the arcs from the centre of the identifier 79. FIG. 8 shows an identifier 89 (specifically an alphanumeric code reading “A1234556789A”) using a conventional typeface where the code is arranged in a circular pattern. FIG. 9 shows an identifier 99 which again reads “A/I 000000” and has the same increase in size between indicia 94 as in the horizontal identifier 69 of FIG. 6.

[0239] The documents 60, 70, 80, 90 are each constructed using two print workings 61, 71, 81, 91 and 65, 75, 85, 95 (95 not shown) which are applied to opposing sides of a substantially transparent substrate. The documents 60, 70 shown in FIGS. 6 and 7 are similar in arrangement and structure to the cross section of a document 10 shown in FIG. 2g. The document 80 shown in FIG. 8 is similar in arrangement and structure to the cross section of a document 10 shown in FIG. 2e. Finally, the document 90 shown in FIG. 9 is similar in arrangement and structure to the cross section to the document 10 shown in FIG. 2i.

[0240] FIG. 6a shows a first print working 61 applied to the first side of the substrate of a document 60. FIG. 6b shows a second print working 65 applied to the opposing, second side of the substrate of the document 60. Finally, FIG. 6c shows the document 60 as seen in transmission from the first side of the substrate.

[0241] The first print working 61 of FIG. 6a corresponds to the combination of a second background print 22 and indicia 14 of FIG. 2g. As will be seen from FIG. 6a the first print working 61 comprises a first background print 62, the boundary of which defines the boundaries 63a of a plurality of unprinted first indicium receiving areas 63. The first print working further comprises a plurality of indicia 64 which form the identifiers 69 applied to the document 60. Each indicium 64 is located within a respective first indicium receiving area 63, such that the juxtaposition of each indicium 63 and the first background pint 62 defines a keyline 68 which extends around each indicium 63. As mentioned above, the first indicium receiving areas 63—and therefore the keyline 68 formed within the indicium receiving areas 63—are unprinted in the first print working 61.

[0242] The second print working 65 corresponds to the combination of the first background print 12 and the indicium receiving print 20 of FIG. 2g. As shown in FIG. 6b the second print working 65 comprises a second background print 67 which defines the boundaries 66a of a plurality of second indicium receiving areas 66. The plurality of second indicium receiving areas 66 share the same lateral extents as the first indicium receiving areas 63. Furthermore, the first and second print workings 61, 65 are applied to the document 60 in register such that the first and second indicium receiving area 63, 66 are congruent. In other words, the first and second indicium receiving areas 63, 66 share the same lateral extents and positioning in document 60, as will be seen in FIG. 6c.

[0243] The second print working 65 further comprises a plurality of indicium receiving prints 68a provided within the plurality of second indicium receiving areas 66 defined by the second background print 67. Each of the indicium receiving prints 68a extends between the boundary 66a of the respective second indicium receiving area 66 and the boundary of the respective indicium 64 provided laterally within said respective indicium receiving area 66 (but to the opposing first side of the document 60 substrate). Therefore, the indicium receiving prints 68a define an internal unprinted region which has the same lateral extent of the respective indicium 64 (as applied to the first side of the substrate of the document 60). The indicium receiving prints 68a form a plurality of printed keylines 68 applied to the second side of the substrate of the document 60, and extending in a lateral direction around the boundaries of the indicia 64.

[0244] The first background print 62 and second background print 67 are coloured and semi-transparent. Therefore, when viewed from the first side of the document in transmission, as shown in FIG. 6c, the indicia 64 is seen surrounded by a keyline 68 which exhibits the appearance of the indicium receiving print 68a, and against the superimposed combination of the first background print 62 and second background print 67 (i.e. the indicia 64 are separated from the superimposed first background print 62 and second background print 67 by the keylines 68).

[0245] The indicium receiving areas 63b, 66b in which the indicia “A”, “I” and “I” are provided are not separated or laterally spaced. Instead, the background prints 61, 65 provided to the first side of the document 90 defines continuous indicium receiving areas 63b, 66b in which all three indicia appear when the document 60 is viewed in transmission. In contrast, the indicium receiving areas 63, 66 in which the “0” indicia appear are not continuous and are laterally spaced.

[0246] FIGS. 7a and 7b show the print workings 71, 75 used to form the document 70 shown in FIG. 7c. The document 70 and the print workings 71, 75 have a similar structure and features as the document 60 and print workings 61, 65 shown in FIG. 6. However, the reference signs have been incremented by a value of 10 between the corresponding figures. Rather than an alphanumeric indentifier 69 (as shown in FIG. 6), the document 70 shown in FIG. 7 exhibits a symbolic code formed of indicia 73 in the form of curved line elements or glyphs.

[0247] Preferably each of the printed features of FIGS. 6 and 7 visually contrast. For instance, in the document 60 of FIG. 6 the first background print 62 may appear pink, the indicium receiving prints 68a (and therefore the keylines 68) may appear mauve, the indicia 64 may appear indigo, and the second background print 67 may appear blue. The first background print 62 and the second background print 67 of the document 60 in FIG. 6 exhibit anti-scan line screen patterns. Equally, in FIG. 7 the first background print 72 may be an orange anti-scan pattern, the indicium receiving prints 68a may be unpatterned green regions, the indicia 74 may be unpatterned orange regions, and the second background print 77 may be a green anti-scan pattern.

[0248] The document 80 of FIG. 8 has a similar structure to the document 10 shown in FIG. 2e. As mentioned above, the document 80 comprises a substantially transparent substrate. FIG. 8a shows a first print working 81 applied to the first side of the document substrate. FIGS. 8b shows a second print working 85 applied to the opposing, second side of the substrate. FIG. 8c shows the document 80 as seen in transmission.

[0249] The first print working 81 of the document comprises a first background print 82 defining the boundaries 83a of a plurality of first indicium receiving areas 83. The first indicium receiving areas 83 are spaced laterally from one another such that the lateral regions 83a are not joined and do not overlap one another. The first print working 81 further comprises a corresponding plurality of indicia 84 each of which is provided within a respective indicium receiving area 83, such that a single indicium 84 is printed within each indicium receiving area 83. The juxtaposition of the first background print 82 and the indicia 84 generates a corresponding plurality of keylines 88 extending between the boundaries 83a of each indicium receiving area 83 and the boundary of the respective indicium 84. This keyline 88 (i.e. the region separating the boundaries 83 of each indicium receiving area 83 and the boundary of the respective indicia 84) is unprinted in the first print working 81.

[0250] The second print working 85 of the document shown in FIG. 8 comprises a second background print 87. The second background print 87 defines the boundaries 86a of a plurality of second indicium receiving areas 86 which share the same lateral extents as the first indicium receiving areas 83 in the first print working 81. The first and second print workings 81, 85 are applied to opposite sides of the substrate of the document in register such that first and second indicium receiving areas 83, 86 are congruent in the full document 80. In other words the first background print 82 and the second background print 86 each define a plurality of indicium receiving areas 83, 86 with the same lateral extents and positions in the document 80 shown in FIG. 8c. Therefore, the keylines 88 are defined between the boundary 86a of each second indicium receiving area 86 and the boundary of the respective indicium 84. The indicium receiving areas 86 defined by the second background print 87 are unprinted in the second print working 85.

[0251] The first background print 82 and the second background print 87 are at least semi-transparent. Therefore, when viewed in transmission from the first side of the substrate as shown in FIG. 8a the document 80 exhibits the indicia 84 surrounded by an unprinted, substantially transparent keyline 88 seen against the superimposed combination of the first background print 82 and the second background print 87. The printed features preferably have contrasting visual appearances and may be easily distinguished from one another and the registration of the features may be easily verified by an observer. The security of the document is further increased if the printed print exhibit different visual appearances. For instance, the first background print 82 may be formed of a semi-transparent green ink, the indicia 84 be formed of an opaque green ink and the second background print 87 may be formed of a semi-transparent blue ink.

[0252] Finally, in FIG. 9 there is shown a document 90 in which the identifier 99 is split or separated into two separate parts 94b, 94c applied to opposing sides of a substantially transparent substrate of the document 90. Each part 94b, 94c of the identifier includes one or more full indicia 94 and multiple parts of further indicia 94 which are split across the two parts 94b, 94c. Therefore, the structure of the document 90 of FIG. 9 is similar to that of the document 10 shown in FIG. 2i. The parts 94b of the identifier 99 (which includes both a whole indicium “/” and the left halves of each “0” indicium) applied to the first side of the substrate preferably have a different appearance to the parts 94c of the identifier 99 (which includes the whole indicia “A” and “I” and the right halves of each “0” indicium) applied to the second side of the substrate, as illustrated by the difference in hatching between the two parts 94b, 94c of the identifier 99.

[0253] FIG. 9a shows a first print working 91 applied to the first side of a document substrate which is substantially transparent. The first print working 91 comprises a background print 92. The background print 92 is an embossed latent line image which exhibits different appearances when viewed at different viewing angles, as will be discussed further below.

[0254] The boundaries of the first background print 92 define the boundaries 93a of a plurality of indicium receiving areas 93. The first print working 91 further comprises the first part 94b of the identifier 99, and includes the full indicium “/” and the left half (portion) of each “0” indicia as viewed from the first side of the substrate. The indicium “/” and the parts of the indicia “0” of the first background print 91 are provided within the indicium receiving areas 93. The indicium receiving areas 93 are otherwise unprinted.

[0255] The second print working (not illustrated in an individual drawing) applied to the opposing second side of the document substrate comprises the second part 94c of the identifier 99, and includes the full indicium “A” and “I” and the right half of each “0” indicia as viewed from the first side of the substrate.

[0256] FIG. 9b shows the document 90 in transmission from the first side of the document 90 at an angle normal to the plane of the document 90 (such that it corresponds to the view of FIGS. 6c, 7c and 8c). The first print working 91 and second print working are applied to opposite sides of the substrate in register such that the parts 94b, 94c of the identifier 99 are provided in register (i.e. positioned and aligned laterally) to correctly form the indicia 94 of the identifier 99.

[0257] Each of the indicia 94 are positioned laterally within a respective indicium receiving area 93. A keyline 98 formed by the juxtaposition of the indicia 94 and the background print 92 extends around the boundary of each indicium 94, such that the keyline 98 extends between each indicium 94 and the background print 92 from the boundary of the indicia 94 and the boundary 93a of the respective indicium receiving area 93. The keyline 98 is unprinted on both the first and second sides of the substrate.

[0258] It is noted that the indicium receiving areas 93b in which the indicia “A”, “/ ” and “I” are provided are not separated or laterally spaced. Instead, the background print 92 provided to the first side of the document 90 defines a continuous indicium receiving area 93b in which all three indicia appear when the document 90 is viewed in transmission. Keylines 98 extending around portions of each of the indicia “A”, “/” and “I” are defined between this indicium receiving area 93 and the background print 92. In contrast, each of the “0” indicia are provided in an individual indicium receiving area 92a, said areas 92a being laterally spaced from one another and the indicium receiving area 92a in which “A”, “/” and “I” are received or provided.

[0259] When the document 90 is viewed in transmission from the first side of the substrate (as shown in FIG. 9b) the parts 94b, 94c of the identifier 99 applied to opposing sides of the substrate are viewed in combination and the identifier 99 is seen as a whole. Furthermore, an unprinted and substantially transparent keyline 98 extends around each indicium 94 of the identifier 99, separating the indicia 94 from the background print 92.

[0260] As discussed above, the parts 94b, 94c of the identifier 99 applied to opposing sides of the document preferably exhibit different appearances (e.g. a different colour, tint, transparency, reflectivity, or pattern). The parts 94b of the identifier 99 comprised in the first print working 92 (i.e. the slash “/” and the left-hand halves of the “0” indicia) may appear blue, whereas the parts 94c of the identifier 99 comprised in the second print working 95 (i.e. the “A”, “I”, and the right-hand halves of the “0” indicia) may appear green.

[0261] The background print 92 is an embossed latent line image which exhibits an optically variable effect, wherein the appearance of the background print 92 changes as the viewing angle changes. At angles which are substantially perpendicular to the plane of the document (i.e. angles normal to the document) the background print 92 does not exhibit any obvious pattern, as shown in FIG. 9b. However, when tilted a latent image is observed.

[0262] As shown in this example, preferably the embossed latent image formed in the background print 92 is conceptually linked to the identifier 99 applied to the document 90. For instance, as shown in FIG. 9c, the embossed latent image may exhibit the numerical portion of the identifier 99: “000000”. Therefore, a viewer can compare the latent effect exhibited by the background print 92 to indicia 94 so as to authenticate the document 90. Such embodiments increase the security of the document 90.

[0263] In addition, the embossed lines of the latent image of the background print 92 will also provide a distinct tactile effect. Therefore a bearer may be able to distinguish the background print 92 from the unprinted keyline 98 and the printed indicia 94 by both sight and touch. This combination of properties is not easy for a would-be counterfeiter to reproduce using conventional printing technologies for producing large numbers of uniquely identified documents and therefore increases the security of the document 90.

[0264] In alternative embodiments of documents according to the present invention one or more of the background print(s) may exhibit alternative optically variable effects. For instance, the first and/or second background print may comprise a lenticular device, diffractive structure (e.g. a hologram or kinegram), moire magnifier, an optically variable pigment or ink, or an alternative optically variable device. These documents offer increased security.

[0265] In each of the specific embodiments discussed above the documents comprise the same structure or cross section at each indicium. Therefore, each of the indicia in an identifier exhibits keylines with similar appearances. However, this is not essential, and alternatively the appearance of a keyline and extent that each keyline extends around its respective indicium may be varied within a document.

[0266] For instance a document (and series of such documents) may be provided with an identifier formed of a plurality of indicia, wherein: one or more of the indicia are provided without any keyline; one or more of the indicia which are partially or wholly surrounded by an unprinted keyline; and/or one or more of the indicia which are partially or wholly surrounded by a printed keyline. In addition a single indicium may be provided with multiple keylines which extend round different portions of the indicium and exhibit different properties (e.g. such that the different keylines visually contrast). These variations further complicate reproduction of documents in the series and increase the security of the series.

[0267] FIGS. 10 and 11 illustrate schematically web-fed printing systems for manufacturing the documents discussed above. In each case a substrate 110 with opposed first and second sides 110a, 110b travels in direction D.sub.1 through one or more printing stations. In each case, if the substrate 110 is not self-supporting a carrier layer (not shown) may be used. The printing stations are preferably digital printing systems (e.g. inkjet printing, laser printing, dye sublimation, or xerography systems). However, this is not essential.

[0268] FIGS. 10(a) and 10(b) illustrate schematically two system layouts 100, 200 for manufacturing a document where print workings are applied to a first side 110a of a substrate 110 (i.e. the document is printed “single sided”).

[0269] FIG. 10(a) shows a printing technique and system 100 where one or more print workings are applied to a first side 100a of a document substrate 110. A continuous horizontal web of substrate 110 moves in direction D.sub.1. The substrate has two opposing sides 110a, 110b. As shown, the first side 110a is the upper surface 110a of the web, whilst the second side 110b is the lower surface of the web.

[0270] Two print stations 120, 130 are located in contact with or adjacent to the first side 110a of the substrate web. At each print station 120, 130 one or more print workings or layers are applied to the upper surface 110a of the substrate 110.

[0271] The print stations 120, 130 apply print workings to the first side 110a of the substrate 110 in sequence.

[0272] For instance, when manufacturing a document 10 as shown in FIG. 2a or a document 30 as shown in FIG. 4a, the first print station in direction D.sub.1 may apply a first print working comprising the background print 12, 32 and the second print station in direction D.sub.1 may apply a second print working comprising an identifier formed of a plurality of indicia 14, 34. Where the document 10, 30 comprises a printed keyline region 20, 40 as shown in FIGS. 2b, 2c, 4b, 4c and 4d the indicium receiving print 20, 40 may be provided by the first print station 120 as part of the first print working or by the second print station 130 as part of the second print working. Alternatively, the indicium receiving print 20, 40 may be applied as a separate print working by either the first or second print stations 120, 130, or by an alternative print station not shown in FIG. 10a.

[0273] Alternatively, the printed features discussed above may be applied simultaneously to the first side 110a of the substrate 110 in a single print working using a single print station 120 as in the system 200 shown in FIG. 10(b).

[0274] The simultaneous printing system 200 illustrated using FIG. 10(b) may be more accurate than the system 100 shown in FIG. 10(a). This is because it may be difficult to accurately locate or align the different print stations 120, 130 of FIG. 10(a) relative to each other. Consequently, it may be difficult to achieve an accurate, or close, registration between the print workings and layers applied to the opposing sides of the substrate.

[0275] FIGS. 11(a), 11(b) and 11(b) illustrate schematically three system layouts 300, 400, 500 for manufacturing a document where print workings are applied to each side 110a, 110b of a substrate 110 (i.e. the document is printed “double sided”).

[0276] The system 300 shown in FIG. 11(a) comprises two print stations 320, 330. As will be seen, the first print station 320 is provided above the web of substrate 110 (i.e. on a first side of the web), whereas the second print station 330 is provided below the web (i.e. on a second side of the web). These print stations 320, 330 may apply print workings to the opposing sides 110a, 110b of the substrate 110. The two print stations 320, 330 are offset from one another in the direction of travel D.sub.1 of the web.

[0277] For instance, the first print station 320 may apply a first print working comprising (for instance) a first background print and the second print station 330 may apply a second print working comprising (for instance) a second background print and an identifier, or vice versa. These print workings will be applied sequentially since the print stations 320, 330 are offset from one another in the direction of travel D.sub.1 of the web.

[0278] FIG. 11(b) shows an alternative system 400 for printing on both sides of a web of substrate 110. Two print stations 420, 430 are provided sequentially (i.e. offset in the direction of travel D.sub.1) on the same side of the web. As shown in FIG. 11(b) the print stations 420, 430 are both above the web.

[0279] Between the two print stations 420, 430 the web of substrate 110 is flipped or turned at section 440, such that it is rotated by 180° about the direction of travel D.sub.1. Therefore, the first print station 420 may apply one or more print workings to the first side 110a of the substrate 110 and subsequently the second print station may apply one or more print workings to the second side 110b of the substrate 110. Such a system is more compact as printing stations only need to be provided to one side of the web (e.g. the upper side as shown in FIG. 11b).

[0280] Finally, FIG. 11(c) shows a further system 500 for printing on either side 110a, 110b of a substrate 110 simultaneously. Two print stations 520, 530 are provided on opposing sides of the web so that they may apply one or more print workings to either side 110a, 110b of the substrate 100 simultaneously. The two print stations 520, 530 may be part of a single printer or printing system.

[0281] In practice any of the systems 100 to 500 discussed above may be provided with further upstream or downstream print stations adapted to provide further print workings or layers (e.g. opacifying layers, protective layers, anti-static layers) to the substrate 110 simultaneously, or in preceding or subsequent steps.

[0282] In the examples discussed above, all of the steps described are web-based processes, i.e. layers and print workings are applied to a web of the substrate 110, e.g. in one in-line web-fed process. Typically a web with a large width (e.g. between 0.75 and 1.5 m) is supplied for this purpose.

[0283] However, in alternative embodiments of the present invention, documents are produced using a combination of web fed and sheet fed process steps. For instance, for some process steps it is desirable to reduce the width of the web, e.g. so that shorter (and hence less costly) processing tools can be used. It is also desirable to carry out certain process steps on individual sheets of the material, rather than on a continuous web.

[0284] In some embodiments, at least a first print working is applied using web based processes. These print workings and opacifying layers are applied on one side of a polymer substrate web with a large width (e.g. between 0.75 and 1.5 m). The web is then divided into sheets for sheet fed printing whereby at least a second print working is applied in contact with or above a side of the substrate.

[0285] Converting a web substrate to a sheet substrate (i.e. dividing the web into sheets) may involve slitting the initial web along its longitudinal direction so as to reduce its width, subsequent processing steps utilising processing tools of correspondingly shorter width compared with those of the preceding steps. The slit webs are then converted in sheets by cutting it along its cross direction at intervals spaced in the longitudinal direction. This process is sometimes referred to as “sheeting”. Each sheet will preferably be sized so as carry a plurality of the final documents. Subsequent printing processes and the application of further print workings may then be performed using sheet-fed machinery. The resulting sheets may be divided further before or after printing in order to produce the final documents as required. In other words, documents according to the present invention may be printed using a combination of web-feed and sheet-fed printing steps.

[0286] Alternatively, documents according to the present invention may be solely constructed using sheet-fed processes. In such processes, all print workings and/or layers are applied to a stationary sheet of substrate. This sheet of substrate may be rotated or flipped to apply print workings or layers to its reverse.