| 摘要 |
PURPOSE:To secure the detection of original size and original density by allowing a photodetector to detect different wavelength ranges of light at the time of the original size detection and original density detection respectively. CONSTITUTION:The original size detection is specified with a key and a copy button is pressed, so that a filter 104a is put on an optical path. In this state, a pre-scan is made and reflected light from an original surface is detected by a sensor 102. At this time, the filter 104a transmits only light of low wavelength with the spectral reflection factor of an original press-contacting surface 9a and reflected light from the surface 9a is hardly detected by the sensor 102. The sensor 102, therefore, photodetects only reflected light from the original 20 to securely detect the original size. Then when the original density detection specified with a key, a filter 104b is put on the optical path and preliminary operation is performed similarly. The filter 104b transmits only wavelength corresponding to the spectral reflected factor of the surface 9a having the same reflection factor and accurate density is detected.
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