String detection system

1. A banknote validator, comprising:

a banknote path formed within an interior of the banknote validator to transport a banknote from an opening of the banknote path through the interior of the banknote validator;

a banknote imaging zone defined within a portion of the banknote path, the banknote imaging zone including:

a reflective region in a first portion of the banknote imaging zone, and

a dark region in a second portion of the banknote imaging zone; and

an image sensor configured to capture one or more images of at least a portion of the banknote imaging zone, wherein the banknote passes over at least one of the reflective region and the dark region as the banknote is transported through the interior of the banknote validator.

2. The banknote validator of claim 1 , wherein the reflective region and the dark region of the banknote imaging zone provide a background for the one or more images.

3. The banknote validator of claim 2 , further comprising:

a processor configured to:

perform image processing of at least one of the one or more captured images; and

determine that, as a result of the image processing of the at least one of the one or more captured images, a foreign object is present in the banknote imaging zone.

4. The banknote validator of claim 3 , further comprising two or more light sources disposed above the banknote path to emit light into the banknote path to provide light for imaging of the banknote imaging zone by the image sensor, wherein the two or more light sources are alternatingly illuminated to change a position of a shadow in the banknote path of the foreign object.

5. The banknote validator of claim 3 , wherein the image sensor is further configured to capture one or more baseline images of the banknote imaging zone while the banknote validator is in an idle state, wherein the idle state is a state in which the banknote validator is not accepting banknote deposits.

6. The banknote validator of claim 5 , wherein, to perform at least part of the image processing, the processor is further configured to:

compare the at least one of the one or more captured images with the one or more baseline images; and

identify the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object.

7. The banknote validator of claim 6 , wherein the processor is further configured to perform a pre-defined action in response to determining that the foreign object is present in the banknote imaging zone.

8. The banknote validator of claim 7 , wherein the pre-defined action includes ejecting the banknote from the banknote validator.

9. The banknote validator of claim 1 , wherein the reflective region is disposed below a transparent surface of the banknote path.

10. The banknote validator of claim 1 , wherein the image sensor is further configured to capture the one or more images of the at least a portion of the banknote imaging zone reflected in a banknote imaging sensor.

11. A method of a banknote validator, comprising:

transporting a banknote from an opening of a banknote path through an interior of the banknote validator, wherein the banknote path is formed within the interior of the banknote validator; and

capturing by an image sensor one or more images of at least a portion of a banknote imaging zone, wherein the banknote imaging zone is defined within a portion of the banknote path, and wherein the banknote imaging zone includes a reflective region in a first portion of the banknote imaging zone, and a dark region in a second portion of the banknote imaging zone, and wherein the banknote passes over at least one of the reflective region and the dark region as the banknote is transported through the interior of the banknote validator.

12. The method of claim 11 , wherein the reflective region and the dark region of the banknote imaging zone provide a background for the one or more images.

13. The method of claim 12 , further comprising:

performing, by a processor, image processing of at least one of the one or more captured images; and

determining, by the processor, that, as a result of the image processing of the at least one of the one or more captured images, a foreign object is present in the banknote imaging zone.

14. The method of claim 13 , further comprising:

emitting light from two or more light sources disposed above the banknote path into the banknote path to provide light for imaging of the banknote imaging zone by the image sensor; and

alternatingly illuminating the two or more light sources to change a position of a shadow in the banknote path of the foreign object.

15. The method of claim 13 , further comprising:

capturing by the image sensor one or more baseline images of the banknote imaging zone while the banknote validator is in an idle state, wherein the idle state is a state in which the banknote validator is not accepting banknote deposits.

16. The method of claim 15 , wherein performing at least part of the image processing includes:

comparing by the processor the at least one of the one or more captured images with the one or more baseline images; and

identifying by the processor the foreign object within the reflective region or within the dark region in the at least one of the one or more images based on a color or a transparency of the foreign object.

17. The method of claim 16 , further comprising:

performing by the processor a pre-defined action in response to determining that the foreign object is present in the banknote imaging zone.

18. The method of claim 17 , wherein the pre-defined action includes ejecting the banknote from the banknote validator.

19. The method of claim 11 , wherein the reflective region is disposed below a transparent surface of the banknote path.

20. The method of claim 11 , further comprising:

capturing by the image sensor the one or more images of the at least a portion of the banknote imaging zone reflected in a banknote imaging sensor.