Inkjet printing apparatus and method for manufacturing display device

An inkjet printing apparatus comprising:

• a spray area, a circulation area, and an injection area;
• an inkjet head in the spray area, and configured to spray a composition for ink including a plurality of bipolar elements;
• an ink circulation device in the circulation area, and configured to:
• store, from a first time point to a second time point later than the first time point, the composition for ink including a number of the bipolar elements dispersed per unit volume;
• supply the composition for ink to the inkjet head after the second time point via a connection tube connected between the ink circulation device and the inkjet head;
• and
• receive the composition for ink from the inkjet head remaining after being sprayed;
• an ink injection device in the injection area, and configured to provide the composition for ink to the ink circulation device;
• and
• a temperature adjusting device configured to adjust a temperature of each of the spray area, the circulation area, and the injection area,
• wherein the temperature adjusting device comprises:
• a first temperature adjusting device configured to adjust a first temperature of the spray area to be included in a first reference temperature region;
• a second temperature adjusting device configured to adjust a second temperature of the circulation area to be included in a second reference temperature region to maintain, from the first time point to the second time point, the number of bipolar elements dispersed in the composition for ink per unit volume;
• and
• a third temperature adjusting device configured to adjust a third temperature of the injection area to be included in a third reference temperature region, and
• wherein the connection tube comprises a valve configured to adjust a flow rate of the composition for ink provided from the ink circulation device to the inkjet head.