| 摘要 |
PURPOSE:To decrease the number of detecting elements by using at least one of plural page detecting means, and a reference voltage detecting means in common. CONSTITUTION:In case of a booklet of 20 pages, when executing a page detection of page 1 - page 10, voltages of each photodetector S1-S10 are compared by comparing circuits CO1-CO10 by using a photodetector S11 as a reference voltage. Also, when executing a page detection of page 11 - page 20, voltages of each photodetector S11-S20 are compared by comparing circuits CO10-CO20 by using a photodetector S10 as a reference voltage. That is to say, when all the pages are on the right side, the elements S1-S10 are bright, and the element S11-S20 are in a dark state. Therefore, when the circuit is constituted in advance so that the element S1 becomes dark, when the page 1 has been opened, the element S1 is dark against the element S11, and the elements S2-S10 are bright, by which it can be detected to be the page 1.
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