| 摘要 |
A sheet discriminating apparatus comprises, in addition to a first detecting system for detecting light transmitted through a sheet and a second detecting system for detecting light reflected by the front surface of the sheet, a third detecting system for detecting light reflected by the rear surface of the sheet. The light doses sensed by these detecting systems are integrated by respective integrators for a predetermined period of time, and the outputs obtained from the integrators are coupled to an adder and added together therein. The sum output of the adder and a reference signal generator are compared with each other in a comparator, and the determination as to whether the sheet in question is adequate for re-use or not is effected on the basis of the result of the comparison.
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