Patent ID: 7303349

Claim:
A pen adapted to be pressurized including: an axial housing having front and rear ends; a pen refill unit mounted within said axial housing and including a tube for accommodating a medium like ink etc. said tube having front and rear ends; a pen tip provided at the front end of said tube and protruding to the outside from the front end of the axial housing in a fixed state, and a pressurizing pump mechanism provided at the rear end of said medium accommodating tube for pressurizing the inside thereof, said pressurizing pump mechanism including a pressurizing chamber communicating with the inside of the medium accommodating tube, an elastic body adapted to be pushed into the pressurizing chamber, an urging unit for urging said elastic body in a releasing direction to be released from within the pressurizing chamber, and a pressing unit for moving forcedly the elastic body in a direction opposite the releasing direction against the urging force of the urging unit for pushing said elastic body into the pressurizing chamber in an airtight state, whereby the inside of the medium accommodating tube being pressurized when said elastic body is pushed by an operation of the pressing unit into the pressurizing chamber against the urging force of the urging unit, and the elastic body is released from within the pressurizing chamber by the urging force of the urging unit in a pushing-release operation of the pressing unit to maintain the inside of the medium accommodating tube in a state ventilated with ambient air.