| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader capable of simply determining a document size without being influenced by colors of a document and disturbance light. SOLUTION: The image reader includes: a light-receiving signal detection part which when a cover member descends to a first down position, receives light from a setting area emitted to a light source and detects a first light-receiving signal, and when the cover member descends to a second down position lower than the first down position, receives light from the setting area emitted to the light source and detects a second light-receiving signal; a comparison value calculation part for calculating a comparison value indicated by a difference or a rate between the first light-receiving signal and the second light-receiving signal; and a document size determination part for determining a document size by using the first comparison value obtained when receiving light from a first light-receiving position on which disturbance light is not made incident other than a non-incident area on which the disturbance light is not made incident in the setting area and a second comparison value obtained when receiving light from a second light-receiving position in the non-incidence area. COPYRIGHT: (C)2011,JPO&INPIT
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