Patent ID: 7581896
Filing Date: 2009-09-01
Classification: B43K

Abstract:
1. A safety knock-type writing instrument, comprising: a barrel having a cartridge therein; a half gear unit provided on an exterior of the barrel and rotatably seated in a clip, wherein the half gear unit has a shape of an eccentric gear which rotates about a central axis thereof, and comprises: inclined groove part; first and second sidewalls provided outside the first and second inclined groove parts to be perpendicular to the first and second inclined groove parts, the first and second sidewalls guiding and restraining the rotation of the first protrusion within the predetermined angular range; and a knock unit positioned in the barrel, and including first and second protrusions to engage with the half gear unit; wherein the cartridge is retracted into the barrel when the first protrusion of the knock unit disengages from the half gear unit; and the half gear unit rotates in a rotating direction and an opposite rotational direction (Q), in response to reciprocating motion of the knock unit in a pushing direction (F) and a releasing direction (R).