Patent ID: 8225964

Claim:
A self-locking handheld dispenser for use in dispensing an adhesive upon application of a manual force, the self-locking handheld dispenser comprising: a body including a fluid passage for the adhesive and a valve seat in said fluid passage; a valve inside said body, said valve having a valve element configured to move relative to said valve seat between a closed position in which said valve element contacts said valve seat to close said fluid passage and an opened position in which said valve element is separated from said valve seat to open said fluid passage; a trigger mechanically coupled with said valve element of said valve, said trigger configured to move said valve element relative to said valve seat from the closed position to the opened position when said trigger is actuated by a first portion of the manual force; a trigger lock mechanism including a locking member and a handle, said handle configured to receive a second portion of the manual force for moving the locking member relative to said trigger between a locked state that blocks movement of said trigger in response to receiving the first portion of the manual force and an unlocked state that permits movement of said trigger in response to receiving the first portion of the manual force; a biasing member configured to apply a spring force to said trigger lock mechanism effective to return said locking member to said locked state when the manual force is released; wherein said locking member and said handle of said trigger lock mechanism are configured to rotate about a pivot axis when said handle receives the second portion of the manual force; wherein said locking member includes a cam surface having a contacting relationship with said trigger to provide the locked state and thereby block movement of said trigger when the second portion of the manual force is absent from said handle; wherein said cam surface has a cam profile with a first section that is configured to maintain the contacting relationship with said trigger and thereby block movement of said trigger as said locking member rotates about said pivot axis over a first angular arc in response to said handle receiving the second portion of the manual force; wherein said cam surface includes a second section configured to permit said locking member to rotate with an increased angular velocity in comparison with the first section over a second arc about the pivot axis while continuing to maintain the contacting relationship with said trigger and thereby block movement of said trigger; and wherein said first section is a first curved surface, and said second surface is a second curved surface having a smaller radius of curvature than said first curved surface.