Patent ID: 8740855

Claim:
A retractable safety syringe comprising: a syringe body having a distal end and a proximal end; a plunger having a piston disposed within the syringe body, a rigid shaft extending longitudinally through the proximal end of the syringe body, and a thumb platform attached to the rigid shaft configured to traverse the piston distally from a retracted position to a fully extended position, the piston further including a piston seal configured to form a seal between the piston and an inner surface of the syringe body, an automatic retraction mechanism configured to urge the plunger proximally toward the retracted position; a braking mechanism adjacent the proximal end of the syringe body, the braking mechanism including a friction member having an eccentrically-shaped through hole that is elongated in a direction substantially transverse to the rigid shaft, the rigid shaft slideably disposed longitudinally through the through hole, the friction member having a first position and a second position, the through hole being in a first through hole position when the friction member is in the first position and a second through hole position when the friction member is in the second position, the first and second through hole positions being offset from each other along a longitudinal axis of the syringe body, an inner edge of the through hole frictionally engages the rigid shaft to resist a retraction force of the retraction mechanism when the friction member is in the first position and the inner edge of the through hole frictionally disengages the rigid shaft when the friction member is in the second position to permit the retraction force to urge the plunger proximally to the retracted position, while still allowing the plunger to be depressed and retracted manually when the friction member is in the first position.