Liquid ejection apparatus and liquid ejection control method

A liquid ejection apparatus comprising:

• an ejection head including (1) a plurality of ejection openings, (2) a plurality of pressure chambers corresponding to the respective ejection openings and communicating with the corresponding ejection openings, (3) a pair of flow paths communicating with each of the pressure chambers, (4) a supply port communicating with one of the pair of flow paths and supplying liquid to the plurality of pressure chambers, and (5) a collection port communicating with the other of the pair of flow paths and collecting liquid from the plurality of pressure chambers;
• a generation unit configured to generate liquid flow that passes through each of the pressure chambers via the pair of flow paths and to differentiate, for each of the corresponding ejection openings, a first direction of liquid flow passing through one of the corresponding pressure chambers and a second direction of liquid flow passing through another of the corresponding pressure chambers which is opposite the first direction of liquid flow;
• a scanning unit configured to scan the ejection head in the first direction and the second direction;
• and
• a control unit configured to perform printing by causing the scanning unit to scan the ejection head relative to a printing medium and ejecting liquid from the ejection openings corresponding to the pressure chambers of the first direction of liquid flow and from the ejection openings corresponding to the pressure chambers of the second direction of liquid flow to a unit region in which printing is to be completed on the printing medium.