Patent ID: 7819601

Claim:
A pressurized pen comprising: a pen refill unit loaded in a pen cylinder and having a pen tip disposed in the front end portion of a containing tube for containing a medium such as ink; and a pressuring pump mechanism for pressurizing the inside of the rear end opening portion of the medium containing tube in the pen refill unit, wherein the pressuring pump mechanism is associated with a knock mechanism disposed in the rear end portion of the pen cylinder such that said pen tip can be brought from the front end portion of the pen cylinder to the outside by the movements of said pen refill unit in axial direction, wherein said pressuring pump mechanism is constituted to include a pressure member having a front end opening portion communicating with the inside of the medium containing tube and a compression chamber made extensible and contractible in the axial directions, and a push member for coming into and out of contact with the rear end opening portion of said pressure member in the axial directions and for pushing the compression chamber of said pressure member in a gas-tight condition in a compressing direction; said push member is enabled to move toward the rear end opening portion of said pressure member in association with the pushing action of said knock mechanism, wherein the push member is formed to include a front end vent portion facing the inside of the compression chamber from the rear end opening portion of the pressure member, and a seal shoulder portion provided posterior to the front end vent portion and having a larger diameter than that of said front end vent portion and brought into abutment against the rear end opening portion of said pressure member by the pushing action of said knock mechanism thereby to keep the inside of said compression chamber gas-tight.