Liquid ejection head

A liquid ejection head comprising:

• a plurality of pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid;
• a plurality of pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, the upstream flow path of each pair being connected to a first end of the corresponding pressure chamber, and the downstream flow path of said each pair being connected to a second end of the corresponding pressure chamber;
• an upstream common chamber communicating with the upstream flow paths;
• an upstream port communicating with the upstream common chamber at a first end of the upstream common chamber in the first direction;
• a downstream common chamber communicating with the downstream flow paths;
• a downstream port communicating with the downstream common chamber;
• and
• a bypass flow path communicating with the upstream common chamber at a second end of the upstream common chamber in the first direction and with the downstream common chamber, wherein
• a circulation flow rate of the liquid is greater than or equal to a maximum total ejection flow rate of the liquid ejected from the nozzles,
• the circulation flow rate is a flow rate at which the liquid flowing through the upstream flow paths to the downstream flow paths when a flow rate of the liquid entering from the upstream port is substantially equal to a flow rate of the liquid exiting through the downstream port, and
• the maximum total ejection flow rate is a flow rate at a full duty with all nozzles ejecting.

A liquid ejection head, comprising:

• a plurality of pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid;
• a plurality of pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, the upstream flow path of each pair being connected to a first end of the corresponding pressure chamber, and the downstream flow path of said each pair being connected to a second end of the corresponding pressure chamber;
• an upstream common chamber communicating with the upstream flow paths;
• an upstream port communicating with the upstream common chamber at a first end of the upstream common chamber in the first direction;
• a downstream common chamber communicating with the downstream flow paths;
• a downstream port communicating with the downstream common chamber;
• a bypass flow path communicating with the upstream common chamber at a second end of the upstream common chamber in the first direction and with the downstream common chamber;
• and
• a pressure damper provided in the bypass flow path.