Security sheet and a security booklet

1. A security sheet comprising a plastic substrate, the plastic substrate comprising:

first and second outer surfaces of the security sheet;

at least one opaque region at least partially surrounding at least one substantially transparent, plastic window extending through the plastic substrate between the first and second outer surfaces; and

perforations extending through the plastic substrate between the first and second outer surfaces, wherein the perforations form a first data element located partially in the at least one window and partially in the at least one opaque region.

2. A security sheet as claimed in claim 1 wherein the perforations form at least one second data element in the at least one opaque region.

3. A security sheet as claimed in claim 2 wherein the perforations form a third data element entirely located in the at least one window.

4. A security sheet as claimed in claim 1 wherein the perforations form a first plurality of data elements, including the first data element, each of the first plurality of data elements being located partially in the at least one window and partially in the at least one opaque region.

5. A security sheet as claimed in claim 1 wherein the perforations form at least one of:

a first plurality of data elements, including the first data element, located partially in the at least one window and partially in the at least one opaque region; or

a second plurality of data elements in the at least one opaque region; and

wherein the at least one of the first plurality of data elements or second plurality of data elements together form a complete data entry.

6. A security sheet as claimed in claim 5 wherein the complete data entry comprises variable data.

7. A security sheet as claimed in claim 1 wherein the perforations are laser perforations.

8. A security sheet as claimed in claim 1 wherein the first data element comprises a grapheme, alphanumeric character, letter, numerical digit, character, logogram, symbol, logo, indicia or portrait.

9. A security sheet as claimed in claim 1 wherein the opaque region is located either within a thickness of the plastic substrate and is separated from at least one of the first or second outer surfaces by at least one transparent region or is formed by at least one opacifying layer making up at least a portion of at least one of the first or second outer surfaces.

10. A security sheet comprising a plastic substrate, the plastic substrate comprising first and second outer surfaces, at least one opaque region at least partially surrounding at least one window, perforations extending between the first and second outer surfaces, wherein the perforations form a first data element located partially in the at least one window and partially in the at least one opaque region, and a second data element located entirely in the at least one window or partially overlapping the at least one window and at least one opaque region, the second data element comprising variable data and applied to the security sheet in a manner different from the perforations.

11. A security booklet comprising:

a security sheet comprising a plastic substrate, the plastic substrate comprising first and second outer surfaces, at least one opaque region at least partially surrounding at least one window, and perforations extending between the first and second outer surfaces, wherein the perforations form a first data element located partially in the at least one window and partially in the at least one opaque region; and

at least one leaf comprising perforations aligned with the perforations of the security sheet such that the perforations of the at least one leaf also form the first data element.

12. A security booklet as claimed in claim 11 further comprising a cover around the security sheet and at least one leaf, wherein the cover comprises perforations aligned with the perforations of the security sheet and the at least one leaf such that the perforations of the cover also form the first data element.

13. A security booklet as claimed in claim 12 wherein the aligned perforations of the security sheet, at least one leaf and cover each form identical complete data entries.

14. A method of forming a security sheet comprising:

forming a plastic substrate comprising first and second outer surfaces of the security sheet and at least one opaque region at least partially surrounding at least one substantially transparent, plastic window extending through the plastic substrate between the first and second outer surfaces; and

forming perforations extending between the first and second outer surfaces and through the at least one window and at least one opaque region, wherein the perforations form a first data element located partially in the at least one window and partially in the at least one opaque region.

15. A method as claimed in claim 14 wherein the perforations are formed by laser perforation.

16. A method as claimed in claim 14 wherein forming the plastic substrate comprises forming a plurality of plastic layers, inserting at least one insert into at least one aperture in the plurality of plastic layers and laminating the plurality of plastic layers and insert together.

17. A method of forming a security booklet comprising the method of claim 14 , comprising attaching the plastic substrate about a fold line to at least one of a leaf or cover, and forming perforations through the plastic substrate and the at least one of the leaf or cover simultaneously.