Ink-jet recording apparatus

An ink jet recording apparatus comprising a record head mounted on a carriage and reciprocated in a width direction of record paper, and a sub-tank mounted on the carriage together with the record head for receiving replenishment with ink via an ink replenishment passage from a main tank, and supplying ink to the record head, wherein air pressure generated by an air pressurizing pump is applied to the main tank, and the sub-tank is replenished with ink from the main tank by the action of the air pressure, the recording apparatus further comprising:

• an on-off valve unit having a valve member provided to an air flow passage from the air pressurizing pump to the main tank and opened under a given or more air pressure for maintaining the air pressure in the air flow passage within a predetermined range;
• and
• a drive system capable of forcibly opening the valve member in the on-off valve unit, thereby releasing a pressurization state of the air pressurizing pump.

An ink jet recording apparatus, wherein pressurized air generated by an air pressurizing pump is applied to a main tank storing ink, and ink is supplied from the main tank to a record head mounted on a carriage by the action of the pressurized air, the recording apparatus comprising;

• a pressure detector, provided to an air flow passage between the air pressurizing pump and the main tank, for detecting pressure of the pressurized air;
• and
• a control system for driving the air pressurizing pump if a pressure detection value obtained by the pressure detector does not reach a predetermined pressure value, and stopping the air pressurizing pump after expiration of a predetermined time if the pressure detection value obtained by the pressure detector reaches the predetermined pressure value.

An ink jet recording apparatus, wherein pressurized air generated by an air pressurizing pump is applied to a main tank storing ink, and a record head mounted on a carriage is replenished with ink from the main tank by the action of the pressurized air, and wherein a pressure detector including a diaphragm displaced upon reception of the pressurized air and a signal generation system for generating a pressure sense signal based on the displacement amount of the diaphragm is provided to an air flow passage between the air pressurizing pump and the main tank, wherein:

• the diaphragm is formed of a material having such a varying hardness changed as to be high in a low temperature state and low in a high temperature state, or a material having such a varying volume as to contract in a low temperature state and expand in a high temperature state, or a movable member for mechanically joining the diaphragm and the signal generation system is formed of a material having such a varying size in a moving direction as to contract in a low temperature state and expand in a high temperature state;
• and
• driving of the air pressurizing pump is controlled based on the pressure sense signal generated by the signal generation system.