Patent ID: 8087840

Claim:
A retractable writing instrument having a dryness prevention device, and including an extraction and retraction control unit, the retractable writing instrument comprising: a casing ( 10 ), having coupling means at a position spaced apart from a nib hole ( 13 ) by a predetermined distance; a cartridge ( 20 ), having a nib coupling protrusion ( 22 ) to couple a nib ( 24 ) and a nib extension tube ( 23 ) to each other; a spring for providing elastic restoring force to the cartridge ( 20 ) in a direction in which the cartridge ( 20 ) is pushed; an O-ring member ( 50 ), which is closely coupled to the nib extension tube ( 23 ); and an openable ring ( 40 ) coupled to the O-ring member ( 50 ) such that the O-ring member ( 50 ) is received in the openable ring ( 40 ), the openable ring ( 40 ) being coupled to the casing ( 10 ) through the coupling means so as to be rotatable with respect to the O-ring member ( 50 ) to open or close a nib opening ( 51 ), so that, when a knock part ( 29 ) is pushed, the openable ring ( 40 ) is rotated with respect to the O-ring member ( 50 ), which is operated in conjunction with the knock part ( 29 ) and the cartridge, such that a through passage is opened in an axial direction of the nib ( 24 ), and the nib ( 24 ) is protruded outside through the nib hole ( 13 ), thus entering a state of permitting use thereof, and, when the cartridge ( 20 ) is moved backwards, the nib coupling protrusion ( 22 ) of the cartridge ( 20 ) holds the O-ring member ( 50 ) and is moved backwards along with the O-ring member ( 50 ), thereby the openable ring ( 40 ) is rotated, thus closing the through passage of the O-ring member ( 50 ).