| 摘要 |
PURPOSE: To realize an image reader in which the dust on an optical path is provented from forming an image on a CCD and an excellent image can be obtained. CONSTITUTION: The reading window 11a of the device main body 10 of an image reader is sealed by a fluorescent lamp 23 illuminating an original P and a glass 24 for dustproof, etc. The reflected light C from the original P by the illumination of this fluorescent lamp 23 is read as video by each of a reflection mirror 25, a lens 26 and a CCD. Each of the reading surface 24a and the dustproof surface 24c of the glass 24 is arranged so that they may be parallel and be opposed with each other in luminous flux guiding the reflected light C from the original P to the side of the lens 26. With these arrangements, this device is composed so as to satisfy the condition of 0.1×Lg< DL×Lo×N (Lg: the length along the optical axis of the dustproof surface 24c of the original P and the glass 24 for dustproof, Lo: the converted air optical path length along the optical axis of the original P and the lens 26, DL: the front valid diameter of the lens 26, N: the refractive index of the glass 24 for dustproof).
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