Optoelectronic document reader for reading UV / IR visible indicia

• US 20050139681A1
• Filed: 12/14/2004
• Published: 06/30/2005
• Est. Priority Date: 03/08/2002
• Status: Active Grant

• Current Assignee: Canadian Bank Note Company, Limited
• Original Assignee: Canadian Bank Note Company, Limited
• Inventors: Balderston, Michael Robert, Premjeyanth, Sivasamy
• Granted Patent: US 7,046,346 B2
• Time in Patent Office: Days
• US Class Current: 235/468
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths

Abstract

A document reader for optoelectronically illuminating, reading and interpreting (i.e. processing and analyzing) indicia appearing on a document in a machine readable zone thereof, wherein the indicia is made visible only under illumination by non-visible light (i.e. UV or IR). UV (or IR) light sources (LED'"'"'s) of the reader are rapidly switched to a stable, peak UV (or IR) illumination frequency or frequency range to illuminate and render visible such covert UV-visible (or IR-visible) indicia. An optoelectronic image sensor (CCD) captures the document image, which includes the indicia rendered visible by the UV source illumination, and the covert indicia is identified from the captured image. An optical path, being folded by two mirrors so as to provide a compact geometry for the reader, extends between a reading surface on which the document is place and the image sensor. A lens configured for focussing light defining an image onto the sensor is provided in the optical path. The reader may also include bank(s) (array(s)) of visible light sources (LED'"'"'s), for illuminating visible indicia, in addition to UV and IR LED arrays and any IR light sources may also be used for illuminating visible OCR characters according to ISO 1831. A controller is provided to sequentially activate each different light source bank.

Claims

1. An optoelectronic document reader for automated reading of first indicia in a machine readable zone of a document, said first indicia being invisible when illuminated with visible light and visible when illuminated with invisible light, said reader comprising:

(a) a reading surface for placement of a document comprising said machine readable zone to be read by said reader;

(b) a plurality of UV LED first light sources spaced apart from said reading surface and configured for illuminating said machine readable zone of a document on said reading surface with invisible light of a predetermined ultraviolet frequency range when said first light sources are activated so as to cause said first indicia to become visible, said first indicia comprising UV fluorescent matter configured for emitting visible light when illuminated by said invisible light of said predetermined ultraviolet frequency range;

(c) an image sensor configured for capturing an image defined by light focussed thereon and producing electronic data representative of said captured image;

(d) an optical path extending between said reading surface and said image sensor and comprising a lens configured for focussing light defining an image onto said sensor;

(e) an optical filter within said optical path and configured for removing reflected light of said first light sources; and

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(f) a document controller configured for identifying said indicia from said captured image and outputting said identified indicia for display and/or processing;

wherein a document image comprising said first indicia, defined by light emitted and/or reflected by said machine readable zone of said document on said reading surface when said first light sources are activated, is transported to said sensor via said optical path and captured by said sensor.

2. An optoelectronic document reader according to claim 1 wherein said optical filter is positioned between said lens and said image sensor.

3. An optoelectronic document reader according to claim 1 wherein said optical path is folded by a plurality of reflecting surfaces within said optical path.

4. An optoelectronic document reader according to claim 2 wherein said optical path is folded by a plurality of reflecting surfaces within said optical path.

5. An optoelectronic document reader according to claim 3 and further configured for automated reading of second indicia in said machine readable zone, said second indicia being visible when illuminated with visible light, said reader further comprising a plurality of second light sources spaced apart from said reading surface and configured for illuminating said machine readable zone with visible light when said second light sources are activated, wherein upon activation of said second light sources said document image comprises said second indicia defined by light emitted and/or reflected by said machine readable zone.

6. An optoelectronic document reader according to claim 5 and further configured for automated reading of third indicia in said machine readable zone, said third indicia comprising characters configured according to OCR standards specification, said reader further comprising a plurality of third light sources spaced apart from said reading surface and configured for illuminating said machine readable zone with light of a predetermined infrared frequency range according to said OCR standards specification when said third light sources are activated, wherein upon activation of said third light sources said document image comprises said third indicia defined by light emitted and/or reflected by said machine readable zone.

7. An optoelectronic document reader according to claim 5 wherein said second light sources are visible LED'"'"'s.

8. An optoelectronic document reader according to claim 7 wherein said third light sources are IR LED'"'"'s.

9. An optoelectronic document reader according to claim 8, and further comprising a controller configured for controlling activation of said light sources.

10. An optoelectronic document reader according to claim 9 wherein said controller is configured for activating said first, second and third light sources in a sequential manner.

11. An optoelectronic document reader according to claim 10 wherein said light sources are activated in the order of said third light sources, said second light sources and said first light sources.

12. An optoelectronic document reader according to claim 10 wherein said light sources are arranged in such a manner that a first bank comprises said first light sources, a second bank comprises said second light sources and a third bank comprises said third light sources, said light sources of each said bank being arranged to provide uniform illumination of said machine readable zone.

13. An optoelectronic document reader according to claim 12 wherein said illumination produced by said banks is of comparable intensity to avoid saturation of said image sensor.

14. An optoelectronic document reader according to claim 10 wherein said illumination of first light sources has a peak wavelength of 370 nm.

15. An optoelectronic document reader according to claim 14 wherein said illumination of said second light sources has a peak wavelength of 650 nm.

16. An optoelectronic document reader according to claim 15 wherein said illumination of said third light sources has a peak wavelength of 850 nm.

17. An optoelectronic document reader according to claim 1 wherein said first indicia comprises encoded information.

18. A method for automated reading of first indicia in a machine readable zone of a document, said first indicia being invisible when illuminated with visible light and visible when illuminated with invisible light, said method comprising:

(a) providing a reading surface for placement of a document comprising said machine readable zone;

(b) providing a plurality of UV LED first light sources spaced apart from said reading surface and configured for illuminating said machine readable zone of a document on said reading surface with invisible light of a predetermined ultraviolet frequency range when said first light sources are activated so as to cause said first indicia to become visible, said first indicia comprising UV fluorescent matter configured for emitting visible light when illuminated by said invisible light of said predetermined ultraviolet frequency range;

(c) providing an image sensor configured for capturing an image defined by light focussed thereon and producing electronic data representative of said captured image;

(d) providing an optical path extending between said reading surface and said image sensor and comprising a lens configured for focussing light defining an image onto said sensor;

(e) providing an optical filter within said optical path, said optical filter configured for removing reflected light of said first light sources; and

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(f) providing a document controller configured for identifying said indicia from said captured image and outputting said identified indicia for display and/or processing;

whereby a document image comprising said first indicia defined by light emitted and/or reflected by said machine readable zone of said document on said reading surface when said first light sources are activated, is transported to said sensor via said optical path and captured by said sensor.

19. A method according to claim 18 whereby said optical filter is positioned between said lens and said image sensor.

20. A method for automatically reading first indicia in a machine readable zone of a document, said first indicia being invisible when illuminated with visible light and visible when illuminated with invisible light, said method comprising:

(a) illuminating, with invisible light of a predetermined ultraviolet frequency range, said machine readable zone of a document placed on a reading surface, whereby said illuminating comprises activating a plurality of UV LED first light sources spaced apart from said reading surface so as to cause said first indicia to become visible, said first indicia comprising UV fluorescent matter configured for emitting visible light when illuminated by said invisible light of said predetermined ultraviolet frequency range;

(b) optically filtering light within an optical path extending between said reading surface and an image sensor, for removing reflected light of said first light sources;

(c) focussing light defining a document image, within said optical path, onto said image sensor; and

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(d) identifying said indicia from said document image focussed onto said image sensor, for display or processing;

whereby said document image comprising said first indicia is transported to said sensor via said optical path when s