| 摘要 |
PURPOSE:To detect original size with simple constitution by arranging plural pairs of conductors adjacently each other on prescribed positions of an original cover, applying a high voltage between each pair of conductors and detecting the voltage change of one conductor of each pair. CONSTITUTION:When a power supply switch is turned on and a copying machine is turned to an operating state, a DC high voltage is applied to each pair of conductors 7a, 7b. Thereby, output signals from both amplifiers 10, 12 are equal when an original is not adsorbed by the original cover 3, and under the adsorbed state, an output signal from the amplifier 10 is increased. Therefore, whether the original is adsorbed or not can be discriminated by a microcomputer 14 on the basis of a compared output signal from a comparator 13 which is decided by the difference between the output signals of both the amplifiers 10, 12. When the original is in the adsorbed state, the size of the adsorbed original can be detected by the compared output signals from plural comparators 13.
|
