Patent ID: 7182197

Claim:
An optical sensing device for detecting optical features of valuable papers, comprising first and second photocouplers positioned in the vicinity of and on the opposite sides of a passageway for guiding the transported valuable paper; said first photocoupler comprises a first light emitting element for emitting a first light of a first wavelength, and a first light receiving element adjacent to said first light emitting element; said second photocoupler comprises a second light emitting element for emitting a second light of a second wavelength different from the first wavelength, and a second light receiving element adjacent to said second light emitting element; the first light emitting element is apposed to the first light receiving element transversely to the transported direction of the valuable paper and in alignment with the second light receiving element across the passageway; the second light emitting element is apposed to the second light receiving element transversely to the transported direction of the valuable paper and in alignment with the first light receiving element across the passageway; the first light receiving element receives the first light reflected on the valuable paper from the first light emitting element and the second light that penetrates the valuable paper from the second light emitting element; the second light receiving element receives the second light reflected on the valuable paper from the second light emitting element and the first light that penetrates the valuable paper from the first light emitting element; one of the first and second lights is an infrared ray, and the other of the first and second lights has a wavelength other than wavelength of infrared ray; and the first and second light emitting elements are turned on at different points in time from each other.