Printer and mark detection method

Abstract

A printer includes: a sensor; a calculation unit that calculates an average value of mark levels and a permissible range in accordance with the average value, the mark levels being output levels of the sensor that has read a mark on a sheet a given number of times; a setting unit that, when the mark levels read the given number of times fall within the permissible range, sets a middle value between a white level and the average value as a determination value of existence or nonexistence of a next mark, the white level being an output level of the sensor when a non-marking domain of the sheet is read; and a determination unit that determines that the next mark has been detected when a mark level at the time of reading of the next mark is less than the determination value of existence or nonexistence of the next mark.

Dependencies are inferred from the claim text.