Inkjet printing apparatus

An inkjet printing apparatus that discharges ink onto a printing medium to perform printing, comprising:

• an ink circulation path including a plurality of heads configured to discharge ink, a supply tank in which ink supplied to the plurality of heads is stored, a plurality of supply-side individual pipes connected to the plurality of heads, respectively, a supply-side manifold that has an upstream end communicating with the supply tank and is forked into the plurality of supply-side individual pipes, a collecting tank in which ink collected from the plurality of heads is stored, and a feedback pipe connecting the collecting tank and the supply tank;
• a heater that is interposed in the feedback pipe and is configured to heat ink flowing from the collecting tank to the supply tank;
• a feedback-side temperature sensor that is interposed between the heater and the supply tank in the feedback pipe and is configured to detect a temperature of ink in the feedback pipe;
• a supply-side temperature sensor that is interposed in the supply-side manifold and is configured to detect a temperature of ink in the supply-side manifold;
• and
• a control unit electrically connected to each of the heater, the feedback-side temperature sensor, and the supply-side temperature sensor, wherein
• the control unit determines whether a first difference value obtained by subtracting a result of detection of the temperature of the ink in the supply-side manifold by the supply-side temperature sensor, from a first target temperature of the ink in the supply-side manifold, applies to a first phase in which the first difference value is equal to or larger than a first reference value, or a third phase in which the first difference value is smaller than a second reference value smaller than the first reference value, and
• when the temperature is determined that the first difference value applies to the first phase, the control unit controls driving of the heater in accordance with a value obtained by multiplication of a second difference value by a first coefficient, the second difference value being obtained by subtracting a result of detection of the temperature of the ink in the feedback pipe by the feedback-side temperature sensor from a second target temperature of the ink in the feedback pipe, and
• when the temperature is determined that the first difference value applies to the third phase, the control unit controls driving of the heater in accordance with the value obtained by multiplication of the second difference value by the first coefficient and a value obtained by multiplication of the first difference value by a third coefficient.