Patent ID: 8096722

Claim:
A writing instrument comprising: a barrel extending along a longitudinal axis X between a rear end and a front end provided with an opening, wherein said barrel includes a window; a writing tip that can move between an exposed position in which said writing tip emerges through the opening and a retracted position in which said writing tip is housed within said barrel; a moving member connected to said writing tip; and a side button that collaborates with said moving member, said side button capable of moving in a general radial direction through the window between a first position in which said writing tip is retracted and a second position in which said writing tip is exposed, wherein said side button includes a guide in which a locking member can move between an unlocked position and a locked position, wherein, in said locked position, the locking member engages with a retaining element arranged in said barrel and for which said side button is immobilized with respect to said barrel, the locking member being urged, at least when said side button is in the second position, towards the locked position.