Liquid circulation device, liquid discharge device and liquid discharge method

A liquid discharge device comprising:

• a liquid discharge head provided inside with a liquid pressurizing chamber and also with a nozzle hole through which liquid is discharged;
• a liquid chamber configured to store the liquid therein to be sent to the liquid discharge head;
• a pressure sensor configured to detect a pressure inside the liquid chamber;
• a motor configured to pressurize the liquid chamber by gas;
• a supply pump configured to supply the liquid from a liquid tank to the liquid chamber;
• and
• a controller configured to compare a value of a pressure fluctuation velocity with a pressure fluctuation velocity threshold determined from a pressure fluctuation value at a time of discharging and a pressure fluctuation value when a temperature changes, and to drive either one of the motor and the supply pump based on a comparison result to pressurize the liquid pressurizing chamber,
• wherein the supply pump supplies the liquid when the detected pressure is lower than or equal to a predetermined pressure value and the pressure fluctuation velocity is greater than the pressure fluctuation velocity threshold, and
• the motor adjusts the pressure using gas when the detected pressure is lower than or equal to the predetermined pressure value and the pressure fluctuation velocity is smaller than the pressure fluctuation velocity threshold.