To provide a sheet feeding device equipped with a discriminating structure for a failure in sensing to make self-diagnosis about whether a double feed sensing element operates normally or not.
The sheet feeding device equipped with a function to sense double feed is furnished with a stacker, a sheet feeding means to feed sheets on the stacker upon separating one by one, a double feed sensing means installed on a sheet transport path in the downstream, a sheet sensing means to sense whether sheet exists in the double feed sensing means, and a failure discriminating means for the double feed sensing means, wherein the double feed sensing means is composed of a signal emitting element and a signal receiving element installed confronting on the sheet transport path, while the failure discriminating means discriminates any failure in sensing the double feed on the basis of the output signal from the signal receiving element and the sensing signal given by the sheet sensing means. The failure discriminating means is furnished with a comparing means to compare the output value of the signal receiving element with the predetermined reference value, and discrimination is given as any failure existing in sensing the double feed if the result from comparison signifies that the output value of the signal receiving element when none sheet is sensed by the sheet sensing means is smaller than the reference value or that the output value of the signal receiving element is greater than the reference value.
HIROSE SHUNICHI
YAMASHITA MASASHI
Koji Mizuno
Toshiro Nakamura