Optical linear sensor unit
A reflective member is disposed on the optical path from the linear light source to the lens array. An ultraviolet light blocking filter is provided closer to a light-receiving unit than the reflective member. A color filter is provided closer to the light-receiving unit than the ultraviolet light blocking filter. A light-receiving surface of the light-receiving unit has a first region opposed to the reflective member without the ultraviolet light blocking filter and the color filter interposed therebetween, a second region opposed to the reflective member and the ultraviolet light blocking filter without the color filter interposed therebetween, and a third region opposed to the reflective member, the ultraviolet light blocking filter, and the color filter.
1. An optical linear sensor unit comprising at least: a linear light source including an ultraviolet light source and a visible light source, for use as an illumination light source that illuminates a paper sheet; a lens array that guides a light reflected from the illuminated paper sheet on a reflected light path passing through the lens array; a light-receiving unit that receives, at a light-receiving surface thereof, the light passing through the lens array; a reflective member is disposed on a direct optical path from the linear light source to the lens array, and is positioned within a reading region of the light-receiving unit and is also outside an image region in which the light-receiving unit reads the paper sheet; an ultraviolet light blocking filter is provided closer proximate to the light-receiving unit than the reflective member along the reflected light path, and the ultraviolet light blocking filter blocks ultraviolet light reflected at the reflective member from entering the light-receiving unit; a color filter is provided closer proximate to the light-receiving unit than the ultraviolet light blocking filter along the reflected light path, and the color filter allows visible light in a specific wavelength range reflected at the reflective member to pass through the color filter and enter the light-receiving unit; and the light-receiving surface of the light-receiving unit has (i) a first region that is opposed to the reflective member without the ultraviolet light blocking filter and the color filter interposed therebetween, (ii) a second region that is opposed to the reflective member and the ultraviolet light blocking filter without the color filter interposed therebetween, and (iii) a third region that is opposed to the reflective member, the ultraviolet light blocking filter, and the color filter.
2. The optical linear sensor unit according to claim 1 , wherein:
the reflective member further includes two partially reflective members spaced apart and provided at positions that are opposed to each end of each of the ultraviolet light blocking filter and the color filter,
respective ends of the ultraviolet light blocking filter and the color filter are provided at positions shifted from each other in a direction parallel to the light-receiving surface of the light receiving unit; and
the second region of the light-receiving surface is formed between the respective ends of the linear light source.
3. The optical linear sensor unit according to claim 2 , wherein:
the lens array has an aperture angle that transmits light incident within a predetermined angle range, and
the respective ends of the ultraviolet light blocking filter and the color filter are provided at positions shifted from each other in a direction parallel to the light-receiving surface, such that a straight line connecting the respective ends is equal to or larger than the predetermined angle range with respect to a direction orthogonal to the light-receiving surface.
4. The optical linear sensor unit according to claim 3 , wherein:
the predetermined angle range is 10° to 20°.
5. The optical linear sensor unit according to claim 1 , further comprising:
an ultraviolet light reference data storage that stores, as ultraviolet light reference data, an amount of light received in the light-receiving unit in a case where a reference amount of ultraviolet light is reflected at the reflective member to enter the first region; and
a first image correction processor that corrects an image obtained by irradiating the paper sheet with ultraviolet light, based on an amount of ultraviolet light received in the first region of the light-receiving unit, and the ultraviolet light reference data stored in the ultraviolet light reference data storage.
6. The optical linear sensor unit according to claim 1 , further comprising:
a visible light reference data storage that stores, as visible light reference data, an amount of light received in the light-receiving unit in a case where a reference amount of visible light is reflected at the reflective member to enter the third region; and
a second image correction processor that corrects an image obtained by irradiating the paper sheet with visible light, based on an amount of visible light received in the third region of the light-receiving censor unit, and the visible light reference data stored in the visible light reference data storage.
7. The optical linear sensor unit according to claim 1 , wherein
the linear light source also includes an infrared light source.
8. The optical linear unit according to claim 7 , further comprising:
an infrared light reference data storage that stores, as infrared light reference data, an amount of light received in the light-receiving unit in a case where a reference amount of infrared light is reflected at the reflective member to enter the third region; and
a third image correction processor that corrects an image obtained by irradiating the paper sheet with infrared light, based on an amount of infrared light received in the third region of the light-receiving unit, and the infrared light reference data stored in the infrared light reference data storage.