Liquid ejection apparatus and drive method for inkjet head

A liquid ejection apparatus, comprising:

• an inkjet head including:
• a nozzle which is configured to eject liquid;
• a pressure chamber which is connected to the nozzle and is configured to contain the liquid to be ejected from the nozzle;
• a piezoelectric element which is arranged on a wall of the pressure chamber on an outer side of the pressure chamber and is configured to apply pressure to the liquid contained in the pressure chamber;
• and a gas chamber which surrounds the piezoelectric element and a space peripheral to the piezoelectric element;
• a dry gas supply device which is configured to generate dry gas having a dew point of not higher than a dew point of an atmosphere around the inkjet head, the dry gas supply device being configured to start supply of the dry gas to the gas chamber before supply of electric power to the inkjet head is started, to continue the supply of the dry gas to the gas chamber while the supply of the electric power to the inkjet head is continued, and to halt the supply of the dry gas to the gas chamber after the supply of the electric power to the inkjet head is halted;
• a dry gas supply flow channel which has a first end and a second end, the first end of the dry gas supply flow channel being connected to the dry gas supply device, the second end of the dry gas supply flow channel being connected to the gas chamber;
• a dry gas supply flow channel opening and closing device which is arranged in the dry gas supply flow channel and is configured to switch between connection and disconnection of the dry gas supply device and the gas chamber;
• a gas return flow channel which has a first end and a second end, the first end of the gas return flow channel being connected to the gas chamber, the second end of the gas return flow channel being open to external air;
• a gas return flow channel opening and closing device which is arranged in the gas return flow channel and is configured to switch between connection and disconnection of the gas chamber and the external air;
• and
• an opening and closing control device which is configured to control the dry gas supply flow channel opening and closing device and the gas return flow channel opening and closing device,
• wherein while the dry gas supply device halts the supply of the dry gas to the gas chamber, the opening and closing control device controls the dry gas supply flow channel opening and closing device to close to disconnect the dry gas supply device and the gas chamber, and controls the gas return flow channel opening and closing device to close to disconnect the gas chamber and the external air.