Patent ID: 7675051

Claim:
A sheet detector mechanism comprising: a sheet detector including, a light source emitting light, and a plurality of photoreceptors arranged in a line in a main-scanning direction spaced at substantially equal intervals to extend across a sheet skew marginal width and to evenly receive light from a light source, the plurality of photoreceptors including a first photoreceptor group overridable by a side edge of the sheet passing through a sheet conveyance passage and a second photoreceptor group connected to the first photoreceptor group and including an opposite end of the plurality of photoreceptors being out of the side edge of the sheet, the first photoreceptor group changing output voltages when overridden by the side edge of the sheet; and a controller configured to adjust a light emission amount of the light source in accordance with characteristics of the sheet so as to maintain the output voltages of the plurality of photoreceptors, regardless of the characteristics of the sheet.