Patent ID: 7381004
Filing Date: 2008-06-03
Classification: B43K

Abstract:
1. A gas pressurized writing instrument comprising: a tube member which has a writing point assembly at a front end, stores ink therein to be fed to the writing point assembly, and opens at a rear end; a casing cylinder which is closed at its rear and encases at least part of the tube member, the casing cylinder creating a space between the tube member and the casing cylinder, the space communicating with the open rear end of the tube member, the casing cylinder being formed of a material that presents low gas permeability or gas impermeability; a compressed gas sealed in the space between the tube member and the casing cylinder; a joint formed of a material that presents low gas permeability or gas impermeability, the joint maintaining the space between the tube member and the casing cylinder airtight, the joint being provided between the casing cylinder and the writing point assembly to encase the tube member in the casing cylinder, keeping the tube member out of contact with outside air while a gas barrier layer that presents low gas permeability or gas impermeability is formed on at least part of an inner surface or an outer surface of the joint; the writing point assembly being fitted into an interior hole formed in a front end of the joint and being welded thereto by heating; and a metallic ring provided between the joint and the casing cylinder, the ring being heated by induction heating to thereby fuse the joint and the casing cylinder, thereby establishing air tightness of the space between the tube member and the casing cylinder.