Liquid discharge apparatus

A liquid discharge apparatus configured to discharge a liquid on a medium, comprising:

• a liquid discharge head including a nozzle and a nozzle surface in which the nozzle is opened;
• a relative movement mechanism configured to perform relative movement between the liquid discharge head and the medium in a direction parallel to the nozzle surface;
• a velocity signal output circuit configured to output a velocity signal related to a relative velocity between the liquid discharge head and the medium;
• and
• a controller,
• wherein, in a case that the liquid is discharged from the nozzle toward the medium, the controller is configured to:
• obtain velocity information about the relative velocity based on the velocity signal output from the velocity signal output circuit;
• perform a constant velocity discharge operation in which the liquid discharge head discharges the liquid from the nozzle while relative movement between the liquid discharge head and the medium at a constant relative velocity is performed;
• and
• perform an acceleration/deceleration discharge operation in which the liquid discharge head discharges the liquid while the relative movement between the liquid discharge head and the medium is performed such that the relative velocity increases or decreases,
• the velocity information includes a plurality of pieces of preceding velocity information,
• in the constant velocity discharge operation, the controller is configured to:
• obtain information about a representative value of the relative velocity based on the pieces of preceding velocity information;
• and
• determine a discharge timing of the liquid from the nozzle based on the information about the representative value,
• in the acceleration/deceleration discharge operation, the controller is configured to:
• calculate a coefficient of a variable in an approximate expression, the variable of the approximate expression being a relative position of the liquid discharge head relative to the medium in the direction parallel to the nozzle surface, and, in the approximate expression, a change in the relative velocity being approximated based on distribution of the relative velocity indicated by the pieces of preceding velocity information;
• and
• determine a discharge timing of the liquid from the nozzle based on the approximate expression.