Abstract: In color reading including an infrared light source, light reflected by a document focuses on a light-receiving part of a sensor IC with different conjugate lengths, due to color aberration of the rod-lens. Since the wavelength of the infrared light is relatively long, the deterioration of the reading resolution appears to be extensive. Here, when reading a document such as a valuable security or a paper bill, a defocusing phenomenon has been prevented, and when reading by infrared light, a high accurate reading characteristic has been realized. As a solution, light is irradiated from a light output window (101a) of a light source (101) and reflected by a document (8), and an infrared light shielding area is provided on a bottom face of a glass (51) placed in an optical path of the light reflected by the document (8), between the document (8) and a sensor IC (3).

Abstract: In color reading including an infrared light source, light reflected by a document focuses on a light-receiving part of a sensor IC with different conjugate lengths, due to color aberration of the rod-lens. Since the wavelength of the infrared light is relatively long, the deterioration of the reading resolution appears to be extensive. Here, when reading a document such as a valuable security or a paper bill, a defocusing phenomenon has been prevented, and when reading by infrared light, a high accurate reading characteristic has been realized. As a solution, light is irradiated from a light output window (101a) of a light source (101) and reflected by a document (8), and an infrared light shielding area is provided on a bottom face of a glass (51) placed in an optical path of the light reflected by the document (8), between the document (8) and a sensor IC (3).