Patent ID: 7959368

Claim:
In a pen having a holder and an ink cartridge device fitted in said holder, the improvement wherein said ink cartridge device comprises: an ink cartridge bar which is a hollow member having a lower end provided with an ink cartridge and an upper end forming a fitting hole provided with internal threads; a connection bar having a lower end forming an insertion portion provided with external threads engageable with said internal threads of said fitting hole of said ink cartridge bar, an upper end forming a first fitting portion, and an intermediate section forming a sideway-projecting circumferential flange, said first fitting portion having a vent hole which is in communication with an interior space formed inside said insertion portion and which is set in communication with said ink cartridge when said insertion portion is screwed into said fitting hole of said ink cartridge bar; a resilient element fitted onto said first fitting portion of said connection bar and retained on said circumferential flange of said connection bar; a retention bar having a lower end forming a second fitting portion fitted into said resilient element and partially and movably fitted over said first fitting portion, said retention bar having a coupling ring above said second fitting portion for coupling to said resilient element, said retention bar having an upper end forming an expanded end portion that has an outside diameter that is greater than a diameter of said resilient element, said second fitting portion having an interior space; wherein when said expanded end of said retention bar is subjected to forcible depression, said resilient element is compressed thereby making said second fitting portion of said retention bar to move up and down with respect to said first fitting portion of said connection bar and therefore causing air to be expelled out of said interior space of said retention bar and forced into said interior space of said insertion portion of said connection bar through said vent hole and communicating said ink cartridge to induce an expulsion force that drives ink contained in said ink cartridge to toward a tip of said ink cartridge thus ensuring writing without any discontinuity of ink scratch, and wherein biasing force induced by said resilient element can be regulated by adjusting engagement between said connection bar and said ink cartridge bar so that an optimum biasing force can be provided to accommodate different writing styles and forces taken by different pen users.