Patent ID: 7144176

Claim:
A pen comprising: a housing including a front opening formed therein, and an ink reservoir including: a cartridge received in said housing, and provided for receiving ink therein; a peripheral swelling having an outer diameter approximately equal to an inner diameter of the cartridge so that in assembly state, the peripheral swelling is engaged to an inner side of the cartridge; at least one sealing ring enclosing the peripheral swelling to prevent ink from flowing out through a gap defined between the peripheral swelling and the cartridge; a peripheral rib extended radially and outwardly from the peripheral swelling to engage with said cartridge and to limit an engagement of said peripheral swelling relative to the cartridge, and to prevent said peripheral swelling from being over engaged into said cartridge; a barrel having an outer diameter approximately equal to an inner diameter of the peripheral swelling so that in assembly state, the barrel is engaged to an inner side of the peripheral swelling; a tube having an outer diameter approximately equal to an inner diameter of the barrel so that in assembly state, the tube is engaged to an inner side of the barrel; a nib having a reduced rear end; an outer diameter of the reduced inner side of the nib being approximately equal to an inner diameter of the tube so that in assembly state, a rear side of the nib is engaged to an inner side of the tube.