Liquid ejection apparatus and liquid ejection head

A liquid ejection head, comprising:

• a liquid ejection unit that includes an ejection port capable of ejecting liquid;
• a pressure control unit;
• a first circulation unit;
• and
• a flow channel
• wherein
• the pressure control unit is capable of being connected with a liquid storing unit for storing the liquid, and is configured to receive the liquid from the liquid storing unit, to supply the liquid to the liquid ejection unit, and to control a pressure of the liquid to be supplied to the liquid ejection unit to be within a predetermined pressure range;
• the first circulation unit is configured to supply the liquid supplied from the pressure control unit to the ejection port and to form a first circulatory flow for circulating the liquid between the liquid ejection unit and the pressure control unit;
• and
• the flow channel is connected to the pressure control unit and forms a part of a circulation flow channel through which the liquid can circulate between the liquid storing unit and the pressure control unit in a second circulatory flow that starts from the liquid storing unit and returns again to the liquid storing unit by way of the liquid ejection head;
• characterized in that
• the pressure control unit includes:
• a supply chamber configured to receive the liquid from the liquid storing unit through the flow channel and to return the liquid to the liquid storing unit through the flow channel;
• a negative pressure chamber that communicates with the liquid ejection unit through the first circulation unit;
• and
• a pressure control valve configured to control a communication state between the supply chamber and the negative pressure chamber according to a pressure difference between the supply chamber and the negative pressure chamber, wherein in a case where the pressure control valve is closed, the first and second circulatory flows are separated from each other.