Liquid supply unit and liquid injection device

A liquid supply unit for injecting predetermined liquid from a liquid storage container storing the liquid to a liquid injection head for injecting the liquid, comprising:

• a first chamber communicating with the liquid storage container;
• a second chamber arranged downstream of the first chamber in a liquid supply direction and communicating with the liquid injection head;
• a wall portion including a communication opening allowing communication between the first chamber and the second chamber;
• an opening/closing member arranged in the communication opening, a posture of the opening/closing member being changed between a closing posture for closing the communication opening and an opening posture for opening the communication opening;
• a biasing member configured to bias the opening/closing member in a direction toward the closing posture;
• a pressing member capable of pressing the opening/closing member in a direction toward the opening posture;
• and
• a flexible film member configured to be displaced based on a negative pressure generated as the liquid in the second chamber decreases and transmit a displacement force thereof to the pressing member;
• wherein the pressing member:
• includes a pivot point, a pressure receiving portion configured to receive the displacement force from the flexible film member and a pressing portion configured to press the opening/closing member against a biasing force of the biasing member, and a flat plate portion having the pivot point arranged on one end side, the flat plate being rotatable about the pivot point;
• the pressure receiving portion is set at a predetermined position of the flat plate portion;
• and
• the pressing portion is set between the pressure receiving portion and the pivot point on the flat plate portion;
• and
• the pressing member rotates about the pivot point when the pressure receiving portion receives the displacement force, the pressing portion pressing the opening/closing member by the rotation of the pressing member.