Sheet detecting device for use in an image forming device for detecting presence or absence of a sheet, a right or wrong side of a sheet and the kind of sheet

A sheet detecting device for obtaining information of one or more kinds of sheet to be fed in said sheet detecting device along a sheet carrying path having upper and lower guide members for guiding said sheet one by one, said upper and lower guide members having sides and the sheet detecting device comprising:

• a pair of detecting means for detecting difference between reflectances of a right side and a wrong side of said sheet, provided in both sides of said guide members respectively;
• a reflector member having a reflectance smaller than a minimum of the reflectances of the right side and wrong side of said sheet to be fed in the sheet detecting device, the reflector member being provided in any one of said guide members facing to one of said detecting means;
• and
• judging means for judging the presence or absence of said sheet to be fed in the sheet detecting device based on an output signal of said one of detecting means facing said reflector member and judging the kind and the right or wrong side of said sheet fed in the sheet detecting device based on the difference between output signals of said pair of detecting means.