| 摘要 |
PROBLEM TO BE SOLVED: To provide an original reader which can change light quantity that a light receiving element receives. SOLUTION: In the original reader, the picture of an original is read by irradiating the original with light and guiding light reflected on the original to the light receiving element 15 so as to receive light. Two confronted glass boards 13 and 16 are arranged on the upstream side of the light receiving element 15 on an optical path from the original to the light receiving element 15 by leaving the gap 18 of prescribed width. In such constitution reflected light from the original is transmitted through the two glass boards 13 and 16 before it is made incident on the light receiving element 15, while light becomes strong or weak by the interference of light corresponding to the width d of the gap 18 between the two glass boards 13 and 16 and the wavelength of light. Namely, light quantity can be controlled by appropriately setting the width d of the gap 18 between the two glass boards 13 and 16.
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