Liquid discharge head and liquid discharge apparatus

A liquid discharge apparatus comprising:

• a liquid discharge head including,
• a discharge unit configured to discharge liquid,
• an upstream flow path configured to supply liquid to the discharge unit,
• a downstream flow path configured to collect liquid from the discharge unit, and
• a diaphragm pump configured to send liquid in the downstream flow path to the upstream flow path not via the discharge unit,
• wherein the diaphragm pump includes,
• a pump chamber configured to function as a pump,
• a suction hole configured to suction the liquid in the downstream flow path into the pump chamber, and
• a discharge hole configured to discharge the liquid in the pump chamber to the upstream flow path,
• wherein the pump chamber is formed with an air bubble discharge hole different from the suction hole and the discharge hole, and
• wherein air bubbles in the pump chamber are discharged outside through the air bubble discharge hole by reducing a pressure in the air bubble discharge hole, and
• a pressure reduction unit provided outside the liquid discharge head to reduce the pressure in the air bubble discharge hole.

A liquid discharge head comprising:

• a discharge unit configured to discharge liquid;
• an upstream flow path configured to supply liquid to the discharge unit;
• a downstream flow path configured to collect liquid from the discharge unit;
• and
• a diaphragm pump including a pump chamber configured to send liquid in the downstream flow path to the upstream flow path not via the discharge unit,
• wherein an air bubble discharge flow path is connected to the upstream flow path,
• wherein air bubbles in the pump chamber are discharged outside through the air bubble discharge flow path via the upstream flow path by causing a pressure in the air bubble discharge flow path to be lower than a pressure in the pump chamber, and
• wherein the upstream flow path is provided with a regulation valve configured to prevent the liquid from being suctioned to the air bubble discharge flow path from the discharge unit, not via the diaphragm pump.