US Patent 7395955 Stapler

A stapler includes a body and a strike plate movably mounted to the body between a rest position and a loaded position. The strike plate is adapted to drive a staple into a target object. The strike plate may be moved from the rest position to the loaded position by a loading mechanism against the bias of a power spring, whereupon the energy stored in the power spring is applied to the strike plate to drive the staple. A stapler may include a lockout which inhibits movement of the strike plate toward the loaded position unless a work piece is beneath the stapler body.