Attachment, liquid container, and liquid supply apparatus

An attachment device for receiving liquid from an external retainer and providing such liquid to a liquid ejection apparatus, the attachment device being mountable on the liquid ejection apparatus as a replacement of a liquid retainer that can also supply the liquid to the liquid ejection apparatus, the liquid retainer being detachably mountable on the liquid ejection apparatus, the attachment comprising:

• a liquid chamber for storing the liquid, having flexible walls that can increase and decrease the volume of the liquid chamber;
• a liquid outlet port constructed and adapted to supply the liquid from the liquid chamber to the liquid ejection apparatus;
• a liquid supply port constructed and adapted to receive the liquid into the liquid chamber from an external retainer, the external retainer being arranged external of the liquid ejection apparatus;
• a check valve provided between the liquid outlet port and the liquid supply port, wherein the check valve is constructed and adapted to prevent the liquid in the liquid chamber from flowing in reverse to the external retainer;
• an air chamber adjacent to the liquid chamber, the air chamber constructed and adapted to apply pressure greater than atmospheric pressure to the liquid in the liquid chamber as pressurized air is introduced into the air chamber;
• and
• an air inlet port constructed and adapted so that air having pressure greater than the air pressure in the air chamber can enter the air chamber and increase the air pressure in the air chamber and thereby increase the pressure on the liquid chamber to cause the liquid to flow through the liquid outlet port.