| 摘要 |
A document size detecting apparatus for a copier and others is disclosed which is capable of identifying the size of a document by use of photosensors the numbers of which is smaller than that of the kinds of documents. A scanner is loaded with a pair of photosensors, or light-sensitive elements, which are spaced from each other in a direction perpendicular to a direction in which a scanner scans a document, the photosensors sensing light which is reflected by a document. A length of a document is determined based on a distance travelled by the scanner from a document scanning start position which is in turn calculated based on a light sensing condition of one of the photosensors, while a width of the document is determined based on a light sensing condition of the other photosensor. Even if a document is placed aslant or in any other dislocated position on a glass platen, its size is identified accurately by positioning the photosensor, which is adapted for the detection of a width, offset relative to a direction which is perpendicular to a scanning direction, or by causing the two photosensors to sense at different timings, or by causing each photosensor to sense twice and deciding outputs of the photosensors valid only when the sensed conditions of the photosensors are identical individually.
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