| 摘要 |
PROBLEM TO BE SOLVED: To prevent the quality of a read image from being deteriorated by making the optical characteristics of the respective original reading means of the front surface side and the rear surface side of an original different from each other, thereby eliminating failures such as transmitting light or rear copying by a light source on the facing side of the original, without complicated control such as alternately controlling respective turning on and turning off of the light source of the respective original reading means by the unit of a scanning line. SOLUTION: A front surface reading part 13 and a rear surface reading part 14 set to the optical characteristics of both of the reduced optical system sensors or/and the optical characteristics of an unmagnificated optical system sensor (contact image sensor) to be respectively different. As an optical characteristic value, mainly spectroscopic sensitivity characteristic of the light emitting wavelength distribution/image sensor (photoelectric conversion element) of the light source can be cited. Optical interference can be reduced breaking into discrete parts the composite characteristic of the image signal of the front/back of the original by differentiating the spectroscopic sensitivity of a reading optical system. In addition, light-emitting wavelength distribution is varied by selecting a light-emitting color in the case of using a light-emitting diode for the light source but selecting a fluorescent film when a fluorescent lamp is used.
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