| 摘要 |
PROBLEM TO BE SOLVED: To provide a document illuminator without inviting a remarkable illuminance unevenness on the document surface due to a reflected light. SOLUTION: The document illuminator is equipped with a long-sized lamp 1 disposed in parallel with the reading line of the document, a reflecting plate 2 for making a part of light from the lamp 1 reflect toward the side of the reading line and a document placing plate 3. When the thickness of the document placing plate 3 is denoted to t and the refractive index to n, the irradiating light quantity at the position apart by 2 t.tan (sin-1 [1/n]) from the reading line in the direction intersecting perpendicularly with the reading line is set to 35-75% of the irradiating light quantity at the reading line. The lamp 1 is a discharge tube having an opening part 1a defined by a first opening end edge of the upper side extended along a longitudinal direction and a lower second opening end edge. The aperture angleϕof the opening part 1a seen from the center of the lamp 1 is 50 to 100 deg., and the angleωformed with the direction of the first opening end edge seen from the center of the lamp 1 and the normal direction of the document placing plate 3 is -5 to 45 deg..
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