Patent ID: 7891897

Claim:
A writing instrument comprising: a barrel having a longitudinal length and a central axis extending along the longitudinal length; a writing tip disposed at a lower portion of the barrel and on the central axis; a push button member disposed at an upper portion of the barrel that is opposite the lower portion, the central axis passing through the push button member, said push button member being movable along the central axis between an extended position and a retracted position; a cam member that pivots about a pivot axis from a substantially horizontal orientation to a substantially vertical orientation in response to motion of the push button member from the extended position to the retracted position; and a sliding piston member that is engaged by the cam member, the sliding piston member disposed on the central axis and configured such that a distance of travel of the sliding piston member along the central axis exceeds a distance traveled by the push button member along the central axis when the push button member is moved between the extended position and the retracted position.