The registration sensor uses an actuator. The actuator [A] returns to its home position to turn the sensor off with a spring [B]. The time between the trailing edge of the original passing the actuator and the actuator returning to its default position varies, so a deviation in sub scan registration may occur. Even if it is within the permitted range from a specification viewpoint, because the deviation becomes larger with faster print speeds, there are some newly added SP settings to adjust the deviation of the sub scan registration for each print speed.