A writing instrument may include a barrel having a longitudinal axis, a cartridge, a writing tip, a self-retracting system for sliding the cartridge inside the barrel between a first position wherein the writing tip extends outside the barrel and a second position wherein the writing tip is retracted, the system comprising a button configured to move the cartridge between the first and the second position, and a sealing member configured to be actuated between a closed position closing a writing passage of the writing instrument, wherein the self-retracting system further comprises a linkage that connects the button and the cartridge, the linkage being configured to convert an actuation of the button into a linear motion of the cartridge along the longitudinal axis.

To protect a writing core, a writing utensil includes: a shaft tube; a holder which is inserted through a front opening of a shaft tube and protrudes forward from a front end of the shaft tube; a writing core which is inserted through the holder while coming into contact with an inner peripheral surface of the holder and is supported by the shaft tube so as to protrude forward from a front end of the holder; and a movement direction conversion mechanism which is provided between the shaft tube and the holder and moves the holder forward relative to the shaft tube and the writing core by a force applied to the holder in the shaft tube outward radial direction.

To protect a writing core, a writing utensil includes: a shaft tube; a holder which is inserted through a front opening of a shaft tube and protrudes forward from a front end of the shaft tube; a writing core which is inserted through the holder while coming into contact with an inner peripheral surface of the holder and is supported by the shaft tube so as to protrude forward from a front end of the holder; and a movement direction conversion mechanism which is provided between the shaft tube and the holder and moves the holder forward relative to the shaft tube and the writing core by a force applied to the holder in the shaft tube outward radial direction.

A retractable ink pen including an elongate ink cartridge having a writing end and an exposed ink opening, wherein the writing end moves from a retracted position to an extended position for writing. The retractable ink pen includes a cap including a recess with an inner surface having one of: i) a position structure, and ii) both a first locator and a second locator spaced a distance from the first locator along a first longitudinal axis. The retractable ink pen further includes an elongate barrel including an outer surface having the other of the position structure and both the first locator and the second locator, wherein the position structure is located at the first locator when the writing end is in the retracted position and wherein the locating structure is located at the second locator when the writing end is in the extended position.

A retractable ink pen including an elongate ink cartridge having a writing end and an exposed ink opening, wherein the writing end moves from a retracted position to an extended position for writing. The retractable ink pen includes a cap including a recess with an inner surface having one of: i) a position structure, and ii) both a first locator and a second locator spaced a distance from the first locator along a first longitudinal axis. The retractable ink pen further includes an elongate barrel including an outer surface having the other of the position structure and both the first locator and the second locator, wherein the position structure is located at the first locator when the writing end is in the retracted position and wherein the locating structure is located at the second locator when the writing end is in the extended position.

According to an aspect, a writing instrument is provided. The writing instrument includes a reservoir for storing writing ink, a nib arranged distally to the reservoir and in fluid communication with the reservoir, a porous membrane or mesh surrounding at least a distal portion of the nib, wherein, in a writing position, the porous membrane or mesh is configured to contact the nib, thereby allowing ink to penetrate through the porous membrane or mesh.