Patent ID: 7296942

Claim:
A writing instrument comprising a barrel, a writing fluid container moveable in an axial direction of the barrel whereby a writing tip of the container can be projected from or withdrawn into one end of the barrel, a spring exerting a force biasing the container to the withdrawn position, a trigger extending from the container and projecting through an opening in the barrel whereby the container can be moved against the force of the spring to the projected position, and a mechanism for releasably holding the container in the projected position, said holding mechanism comprising a locking element located within an enclosure at the other end of the barrel, the locking element having a height in the axial direction, wherein the locking element and enclosure are configured such that when the writing tip is in the withdrawn position the locking element is disposed within a portion of the enclosure having a depth in the axial direction that is greater than the height of the locking element and the locking element is freely movable over said depth, and when the writing tip is in the projected position the locking element may be immobilized to hold the writing tip in said projected position.