Patent ID: 7643762

Claim:
A sheet remainder detecting device for detecting the remaining amount of sheets in a sheet stack, comprising: a displacing member displaceable according to the thickness of the sheet stack; a first and a second optical sensors each having a light emitting element for emitting light toward the displacing member and a light receiving element for receiving the light emitted by the light emitting element and reflected by the displacing member; and a controller for discriminating the remaining amount of the sheets based on detection signals of the first and second optical sensors; the displacing member including a light irradiation region to be irradiated with the lights from the light emitting elements and movable according to an amount of displacement of the displacing member, and the light irradiation region having: a first reflecting surface for reflecting the light emitted from the light emitting element of the first optical sensor so that the light receiving element of the first optical sensor can receive the reflected light emitted from the first optical sensor; a second reflecting surface for reflecting the light emitted by the light emitting element of the first optical sensor so that the light receiving element of the second optical sensor can receive the reflected light received from the first optical sensor; a third reflecting surface for reflecting the light emitted from the light emitting element of the second optical sensor so that the light receiving element of the second optical sensor can receive the reflected light received from the second optical sensor; and a fourth reflecting surface for reflecting the light emitted by the light emitting element of the second optical sensor so that the light receiving element of the first optical sensor can receive the reflected light received from the second optical sensor.