An inkjet printer, comprising:
- a sheet conveyor configured to convey a sheet in a conveying direction;
- a printing head configured to eject ink drops on the sheet conveyed by the sheet conveyor;
- a first sensor which is a reflective sensor configured to output a first detection signal corresponding to a received amount of reflected light;
- a carriage mounting the printing head and the first sensor thereon and configured to move in a scanning direction which intersects with the conveying direction;
- a corrugation forming mechanism configured to form the sheet to have a corrugated shape so as to have mountain peak positions and valley bottom positions which are alternately arranged in the scanning direction at a portion facing the printing head, the sheet being deformed toward the printing head at the mountain peak positions and deformed away from the printing head at the valley bottom positions;
- a storage configured to store information representing a plurality of assumed mountain peak positions and a plurality of assumed valley bottom positions, the plurality of assumed mountain peak positions corresponding to positions at which the first sensor faces the mountain peak positions in the scanning direction and the plurality of assumed valley bottom positions corresponding to positions at which the first sensor faces the valley bottom positions in the scanning direction;
- and
- a controller,
- the controller being configured to:
- execute movement of the carriage across the sheet in the scanning direction;
- during the movement of the carriage in the scanning direction, receive the first detection signal from the first sensor;
- after receipt of the first detection signal, identify a first signal level at the plurality of assumed mountain peak positions in the scanning direction based on both the plurality of assumed mountain peak positions stored in the storage and the first detection signal, the first signal level corresponding to the signal level of the first detection signal in a mountain peak zone including the assumed mountain peak position;
- after receipt of the first detection signal, identify a second signal level at the plurality of assumed valley bottom positions in the scanning direction based on both the plurality of assumed valley bottom positions stored in the storage and the first detection signal, the second signal level corresponding to the signal level of the first detection signal in a valley bottom zone including the assumed valley bottom positions;
- after identification of both the first signal level and the second signal level, calculate a signal level difference between the first signal level and the second signal level;
- after completion of calculation of the signal level difference, execute a decision process in which the controller decides whether the calculated signal level difference is less than a predetermined threshold value;
- and
- execute a printing process in which the controller alternately executes, during the movement of the carriage, an ejection process of causing the printing head to eject ink drops, and a conveying process of causing the conveyor to convey the sheet by a predetermined line feed width,
- wherein, in the printing process:
- based on decision of the calculated signal level difference being not less than the predetermined threshold in the decision process, the controller causes the printing head to eject ink drops and causes the conveyor to convey the sheet according to a first condition;
- and
- based on decision of the calculated signal level difference being less than the predetermined threshold in the decision process, the controller causes the printing head to eject ink drops and causes the conveyor to convey the sheet according to a second condition different from the first condition.