Patent ID: 7407245

Claim:
A printing apparatus for carrying out printing on a printing medium comprising: a print head that is movable in a main scanning direction and that is for ejecting ink onto said printing medium; a printing medium feeding section for feeding said printing medium; a sensor that detects said printing medium, said sensor being movable in the main scanning direction; and a controller (a) operative to position said sensor in a first position that is at substantially a center of a width of said printing medium in the main scanning direction, (b) operative to feed said printing medium with said printing medium feeding section, (c) operative to detect at said first position a leading edge of said printing medium with said sensor, (d) operative to move said sensor to a temporary position different from said first position, (e) when said printing medium has not been detected with said sensor at said temporary position, said controller considers a predetermined position being at a same side as said temporary position with respect to said first position, and when said printing medium has been detected with said sensor at said temporary position, said controller is operative to move said sensor to a second position that is a position at an opposite side to said temporary position with respect to said first position, said printing medium not being detected with said sensor at said second position, (f) operative to feed said printing medium with said printing medium feeding section, (g) operative to detect at said second position said leading edge of said printing medium with said sensor, (h) operative to obtain a skew of said printing medium by performing a calculation using numerical values that are based on detection results of said leading edge at said first position and said second position, and (i) operative to change at least one of a starting position, an ending position, and both of these for ejecting ink form said print head, which moves in the main scanning direction, according to said skew that has been obtained.