Liquid discharge apparatus and image forming apparatus

A liquid discharge apparatus comprising:

• a liquid discharge head configured to discharge a liquid;
• a sub tank configured to hold the liquid to supply the liquid to the liquid discharge head;
• a liquid cartridge configured to hold the liquid to be supplied to the sub tank;
• a supply channel configured to connect the sub tank and the liquid cartridge to supply the liquid from the liquid cartridge to the sub tank in a supply direction;
• a circulation channel configured to connect the sub tank and the supply channel to return the liquid held in the sub tank to the supply channel;
• a first channel opening-and-closing mechanism disposed in the supply channel to switch connection and disconnection of the supply channel;
• a second channel opening-and-closing mechanism disposed downstream of the first channel opening-and-closing mechanism in the supply direction in the supply channel;
• a third channel opening-and-closing mechanism disposed in the circulation channel to connect and disconnect the circulation channel;
• and
• circuitry configured to
• operate the first channel opening-and-closing mechanism to disconnect the supply channel;
• operate the second channel opening-and-closing mechanism to circulate the liquid in the sub tank via the circulation channel and the supply channel;
• operate the third channel opening-and-closing mechanism to connect the circulation channel;
• wait until a waiting time has elapsed after connection of the circulation channel and then operate the second channel opening-and-closing mechanism to circulate the liquid in the sub tank via the circulation channel and the supply channel;
• stop the operation of the second channel opening-and-closing mechanism;
• and
• wait until another waiting time has elapsed after stopping the second channel opening-and-closing mechanism and then operate the third channel opening-and-closing mechanism to disconnect the circulation channel,
• wherein the waiting time is different from the another waiting time.

A liquid discharge apparatus, comprising:

• a liquid discharge head configured to discharge a liquid;
• a sub tank configured to hold the liquid to supply the liquid to the liquid discharge head;
• a liquid cartridge configured to hold the liquid to be supplied to the sub tank;
• a supply channel configured to connect the sub tank and the liquid cartridge to supply the liquid from the liquid cartridge to the sub tank in a supply direction;
• a pressure sensor disposed in the supply channel and configured to detect pressure in the supply channel;
• a first channel opening-and-closing mechanism disposed in the supply channel to switch connection and disconnection of the supply channel;
• a second channel opening-and-closing mechanism disposed downstream of the first channel opening-and-closing mechanism in the supply direction in the supply channel;
• and
• circuitry configured to
• operate the first channel opening-and-closing mechanism to connect the supply channel;
• wait until a first predetermined waiting time has elapsed after connection of the supply channel and then operate the second channel opening-and-closing mechanism to feed the liquid from the liquid cartridge to the sub tank;
• stop an operation of the second channel opening-and-closing mechanism;
• and
• wait until the pressure detected by the pressure sensor reaches a predetermined pressure after stopping the second channel opening-and-closing mechanism, and then operate the first channel opening-and-closing mechanism to disconnect the supply channel.