Cap for writing equipment

A cup shaped cylindrical pen body cap for closing off a pen body trunk of a writing instrument, said pen body cap being open at one end and being closed at the other end by a top, said pen body cap further comprising:

• an air vent defined in the pen body cap top for communicating with the atmosphere;
• means for providing airtightness disposed on the inner peripheral surface of said cylindrical pen body cap;
• a miniature cap for covering a tip of said writing instrument, and for defining a first enclosed space between said writing instrument and an inner peripheral face of said miniature cap in which space said tip is disposed, said miniature cap having a top and being concentrically positioned in said cup shaped cylindrical pen body cap, said miniature cap being movable in the axial direction in a second enclosed space, said second enclosed space being formed between the inner face of said pen body cap top, the inner peripheral surface of said cylindrical pen body cap, and said means for providing airtightness;
• an annular resilient seal positioned on the outer face of the top of the miniature cap, said annular resilient seal being sized and positioned for surrounding said air vent and blocking ventilation between said air vent and the inside of the cup shaped cylindrical pen body cap when a pen body trunk is fitted into said cap;
• and
• at least one opening defined in said miniature cap proximate to said miniature cap top and radially outside of said annular resilient seal for communicating said first enclosed space with a portion of said second enclosed space outside of said miniature cap,
• and wherein said means for providing airtightness is installed in a position for pressing against said trunk of said pen body to stop ventilation in the longitudinal direction.