Safety device for preventing needle stick injury with a needle of a medical injection device

A safety device for a medical injection device, comprising:

• a ring configured to be attached to a distal tip of a medical injection device and comprising a first hinge portion;
• and
• a protective shield comprising a second hinge portion pivotally coupled to the first hinge portion, the protective shield configured to adopt successively a storage position in which the protective shield covers the needle tip, a retracted position in which the protective shield uncovers the needle tip, and a safety position in which the protective shield covers the needle tip;
• wherein:
• the ring comprises a lug, the lug extending distally and comprising an internal side and an external side opposite to the internal side, wherein the internal side is closer to a center point of the ring than the external side;
• the protective shield comprises at least one proximal locking member;
• in the safety position, the protective shield is locked on the ring by engagement of the locking member with the lug;
• the locking member is a flexible tab, wherein the flexible tab extends primarily axially and proximally directly from the body of the protective shield, wherein an axial direction is defined as a longitudinal axis of the protective shield;
• and
• the locking member is configured to:
• engage the lug when the protective shield transitions from the retracted position to the safety position, so that the locking member abuts against the external side of the lug and deflects radially outwardly, relative to the axis of the ring wherein the axis of the ring extends through the center point of the ring in a manner that is perpendicular to a radius of the ring, from a body of the protective shield when the protective shield passes from the external side of the lug to the internal side of the lug, and
• remain engaged with the internal side of the lug for maintaining the protective shield in the safety position by abutment of the flexible tab against the internal side of the lug such that the locking member undergoes buckling deformation.