JP2009201149A5 - - Google Patents

Claims (6)

In a document illumination device that illuminates a document by superimposing light emitted from a plurality of light sources arranged in a first direction on the document surface,
  A lens array provided corresponding to each of a plurality of light beams emitted from each of the plurality of light sources, and having a positive refractive power in the first direction and perpendicular to the first direction. A first lens having no refractive power in two directions, a focal length is F, and the first lens and the document surface are disposed at a position separated from the document surface by a focal length F; A second lens having no refractive power in the first direction and having a positive refractive power in the second direction, and each of the plurality of light sources emits light for each color of red, green, and blue A set of light emitting light sources to be covered with a hood lens composed of a convex lens with a convex surface facing the document surface on which the document is placed;
  The focal length of the hood lens is f0, and the distance a from the red, green, and blue light emitting sources to the principal point to the hood lens is arranged to be equal to the focal length f0. An original illuminating apparatus characterized in that an optical axis of a light beam emitted from a green light source among red, green, and blue light-emitting light sources coincides with an optical axis of the hood lens. Side mirrors are arranged on both side surfaces in the first direction of the first lens, and the side mirrors are arranged on both sides in the first direction of the second lens from both side surfaces in the first direction of the hood lens. The document illumination device according to claim 1, wherein the document illumination device is provided over the entire surface. The plurality of light sources arranged in the first direction are all arranged at an equal distance from the document surface, and the focal lengths f0 of the hood lenses provided in the individual light sources are all the same. The focal length f1 of each lens of the lens array that is the first lens changes according to the arrangement in the first direction, and the first lens corresponding to the light source at the center in the first direction The relationship between the focal length f1 of the lens and the focal length f0 of the hood lens is
  3. The document illuminating apparatus according to claim 1, wherein f0> f1, and f0 = f1 as it goes from the central portion toward the peripheral portion, and then f0 <f1. The plurality of light sources arranged in the first direction are such that the central portion in the first direction is closest to the original surface, and further away from the original surface with the light source from the central portion toward the peripheral portion. Arranged in the
  The focal lengths f0 of the hood lenses provided in the individual light sources are all the same, and each lens focal length f1 in the lens array that is the first lens changes according to the arrangement in the first direction, The relationship between the focal length f1 of the first lens corresponding to the light source at the center in the first direction and the focal length f0 of the hood lens is:
3. The document illuminating apparatus according to claim 1, wherein f0> f1, and f0 = f1 as it goes from the central portion toward the peripheral portion, and then f0 <f1. The plurality of light sources arranged in the first direction are all arranged at an equal distance from the document surface, and the focal lengths f0 of the hood lenses provided in the individual light sources are all the same. The focal length f1 of each lens in the lens array which is the first lens changes according to the arrangement in the first direction, and the first lens corresponding to the light source at the center in the first direction The relationship between the focal length f1 of the lens and the focal length f0 of the hood lens is
  f0> f1, passing through f0 = f1 from the central part toward the peripheral part, and then f0 <f1, and the light source arranged at the center in the first direction, For the plurality of light sources excluding the light sources arranged at both ends, the first lens is arranged such that the optical axis of each light source is inclined outward with respect to the optical axis of the light source arranged at the center in the first direction. The document illumination device according to claim 1, wherein a prism is disposed immediately after. An image reading apparatus that illuminates a document with the document illumination device according to any one of claims 1 to 5,
  An imaging optical system that forms an image of light scattered or reflected from the illuminated document;
  An image reading apparatus comprising: an image pickup device that picks up an image formed by the image forming optical system.