Patent ID: 8128213

Claim:
A liquid ejector comprising: a liquid ejection head which ejects a liquid through a nozzle; a first cartridge attaching unit to which a first liquid cartridge is attached in such a way that a liquid is supplyable to the liquid ejection head, the first liquid cartridge including a first section for detection which is used for detecting whether the first liquid cartridge is in an empty state in which an amount of an internal liquid is less than a predetermined remaining amount; a discharge path used for discharging the liquid from the liquid ejection head; a second cartridge attaching unit to which a used liquid cartridge including a second section for detection, which is used and is in the empty state because a liquid therein has been consumed is attached, so that the used liquid cartridge is connected to a downstream end of the discharge path; a pump which is provided in the middle of the discharge path and conveys a liquid in the discharge path to the used liquid cartridge attached to the second cartridge attaching unit; a first empty detector which detects, using the first section for detection, whether the first liquid cartridge attached to the first cartridge attaching unit is in the empty state; an attachment detector which detects whether the used liquid cartridge is attached to the second cartridge attaching unit; a second empty detector which detects, using the second section for detection, whether the used liquid cartridge attached to the second cartridge attaching unit is in the empty state; and a control unit which controls the pump, wherein, when an discharge possible state is established where the attachment detector has detected that the used liquid cartridge is attached to the second cartridge attaching unit and the second empty detector has detected that the used liquid cartridge is in the empty state, the control unit controls the pump in such a way that a predetermined conveyance amount of the liquid is conveyed to the used liquid cartridge attached to the second cartridge attaching unit after the liquid is conveyed from the discharge path to the used liquid cartridge until the second empty detector detects that the used liquid cartridge is no longer in the empty state, and wherein, on the discharge path, a storage tank which temporarily stores a liquid in the discharge path is provided between the pump and the second cartridge attaching unit, and the pump conveys the liquid in the storage tank to the used liquid cartridge attached to the second cartridge attaching unit.