Patent ID: 7972301

Claim:
A retractable safety syringe comprising: a syringe body having a distal end, a proximal end, and inner surface; a plunger having a piston disposed within the syringe body, a rigid shaft extending through the proximal end of the syringe body, a thumb platform attached to the rigid shaft and configured to traverse the piston between a refracted position and a fully extended position, the piston further including a piston seal configured to form a seal between the piston and the inner surface of the syringe body; a needle assembly removably mounted to distal end of the syringe body; a refraction mechanism configured to automatically create a retraction force sufficient to traverse the plunger proximally and withdraw the removably mounted needle assembly into the syringe body; a braking mechanism including a protuberance having a seat and a landing, an outer periphery of the seat being larger than an outer periphery of the landing, a friction material, at least partially surrounding the protuberance, wherein, when the friction material is disposed on the seat, a first friction force between the friction material and the inner surface of the syringe body is created, the first friction force being at least about equal to the retraction force of the retraction mechanism, preventing the refraction force from traversing the plunger proximally, and wherein, when the friction material is disposed on the landing, a second friction force between the friction material and the inner surface of the syringe body is created, the second friction force being less than the retraction force, allowing the retraction force to traverse the plunger proximally and withdraw the removably mounted needle assembly into the syringe body; and a punch attached to the distal end of the syringe body, configured to displace the friction material from the seat to the landing when the piston is traversed to the fully extended position.