1. A method of identifying a document, the method comprising exposing the document to infrared radiation; detecting infrared radiation reflected from or transmitted through a plurality of regions of the document to generate at least one test pattern; determining if the or each test pattern satisfies a predetermined relationship with a predetermined pattern or patterns corresponding to a known document; and, if the predetermined relationship is satisfied, identifying the document as being the same as the known document.
2. A method according to claim 1, wherein the regions are arranged in a regular array.
3. A method according to claim 1, wherein the regions are located on both sides of the document.
4. A method according to claim 1, wherein the regions are arranged in one or more two dimensional arrays.
5. A method according to claim 4, wherein the regions extend over substantially the whole of at least one side of the document.
6. A method according to claim 1, wherein the step of determining if the or each test pattern satisfies a predetermined relationship comprises determining the relationship of the test pattern(s) with a plurality of predetermined patterns corresponding to different documents andor orientations of documents, and identifying the document under test in accordance with the determined relationship.
7. A method according to claim 1, wherein the step of determining the predetermined relationship includes determining whether the degree of similarity between the test pattern(s) and the or each predetermined pattern corresponding to a known document exceeds a first threshold.
8. A method according to claim 7, wherein the step of determining if the or each test pattern satisfies a predetermined relationship comprises determining the relationship of the test pattern(s) with a plurality of predetermined patterns corresponding to different documents andor orientations of documents, and identifying the document under test in accordance with the determined relationship, and wherein determining the predetermined relationship further comprises determining the two predetermined patterns which are most similar to the test pattern, and only identifying the document if the difference between the degrees of similarity to the two most similar predetermined patterns exceeds a second threshold.
9. A method according to claim 1, wherein the document comprises a banknote.
10. A method according to claim 9, wherein the banknote is US currency.
11. A method of handling documents, the method comprising:
transporting the documents past an infrared inspection station;
performing an identification method according to claim 1 at the inspection station; and
controlling the further transport of the documents in accordance with the outcome of the identification method.
12. A method according to claim 11, further comprising transporting each document to an appropriate one of a plurality of output locations depending upon the outcome of the inspection method.
13. A method according to claim 12, further comprising stopping the transport of the documents if a document is not identified.
14. Document handling apparatus comprising an infrared inspection station; a transport system for transporting documents past the inspection station, the inspection station comprising an infrared radiation emitter and an infrared radiation receiver for detecting infrared radiation reflected from or transmitted through a document; and a control system coupled to the transport system and the infrared inspection station to generate at least one test pattern from the infrared radiation reflected from or transmitted through a plurality of regions of the document, to determine if the or each test pattern satisfies a predetermined relationship with the predetermined pattern or patterns corresponding to a known document, and, if the relationship is satisfied, to identify the document as being the same as the known document, and thereafter to control the transport system accordingly.
15. Apparatus according to claim 14, wherein the infrared inspection station comprises two sets of infrared emitters and detectors arranged on opposite sides of the transport path so as to view opposite sides of the documents.
16. Apparatus according to claim 15, wherein the sets of infrared emitters and detectors are offset from one another in the transport direction.
17. Apparatus according to claim 14, wherein the or each array is arranged opposite a black reference surface.
18. Apparatus according to claim 14, wherein the transport system includes a diverter operable by the control system to divert documents to one of a number of output locations in accordance with the determined identity.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of forming a variable pattern across a wafer using a reticle, the method comprising:
forming a plurality of first patterns on the wafer, each of the first patterns having a first readable element; and
forming a plurality of second patterns on the wafer, each of the second patterns having a second readable element, wherein the second patterns are positioned relative to the first patterns by
aligning one of the second patterns relative to one portion of one of the first patterns, and
incrementally misaligning each successive second pattern in a row or a column relative to each successive first pattern, such that each corresponding first readable element and second readable element form the variable pattern.
2. The method of claim 1, wherein the first pattern and the second pattern are formed by two different reticles.
3. The method of claim 1, wherein the first pattern and the second pattern are formed by two patterns on one reticle.
4. The method of claim 1, wherein each of the first patterns has a length, and incrementally misaligning each successive second pattern includes moving the wafer a distance greater than or less than the length of the first pattern.
5. The method of claim 1, wherein each of the first patterns has a width, and incrementally misaligning each successive second pattern includes moving the wafer a distance greater than or less than the width of the first pattern.
6. The method of claim 1, wherein each of the first patterns has an area and each of the second patterns has a larger or smaller area than the first pattern, so that incrementally misaligning each successive second pattern includes forming the larger or smaller area of the second pattern.
7. The method of claim 1, wherein the variable pattern is optically readable.
8. The method of claim 1, wherein the variable pattern is electrically readable.
9. The method of claim 1, wherein the variable pattern forms one or more patterns that indicate the physical location of die within the first pattern and die in the wafer.
10. The method of claim 1, wherein the variable pattern forms one or more electrical components.
11. A method of patterning a wafer, the method comprising:
applying a first reticle image to the wafer repeatedly in order to form a first pattern that repeats across the wafer, each of the first patterns having a first readable element;
applying a second reticle image to the wafer repeatedly in order to form a second pattern that repeats across the wafer, each of the second patterns having a second readable element, one of the second patterns being aligned with respect to a portion of one of the first patterns and subsequent second patterns being offset from subsequent first patterns by a distance that varies across the wafer, the first readable element of one of the first patterns and the second readable element of one of the second patterns forming a variable pattern that varies across the wafer.
12. The method of claim 11, wherein the first reticle image and the second reticle image are formed from one reticle.
13. The method of claim 11, wherein the first reticle image and the second reticle image are formed from two different reticles.
14. The method of claim 11, wherein the variable pattern is optically readable.
15. The method of claim 11, wherein the variable pattern is electrically readable.
16. The method of claim 11, wherein the variable pattern forms one or more patterns that indicate the physical location of die within the first pattern and die in the wafer.
17. The method of claim 11, wherein the variable pattern forms one or more electrical components.
18. The method of claim 17, wherein the electrical components include one or more of resistors, capacitors, diodes, or read-only memory.
19. The method of claim 11 wherein applying the second reticle image comprises varying dimensions of the second reticle image relative to the first reticle image.
20. The method of claim 11, further comprising
moving the wafer a dimension greater than or less than one dimension of the first repeating pattern in order to offset the subsequent first patterns by the varying distance.