Automatic safety syringe

A disposable syringe (100) comprising:

• a syringe body (1) hollow on the inside and open at the front and rear,
• a plunger (40) slidable inside the syringe body (1) with an injection stroke extending from a retracted syringe-filling position to a forward syringe-emptying position, said plunger (40) being provided at the rear with a shaft (50) that can be operated manually and brought out of the syringe body through the rear end (80) thereof,
• an injection needle (10) integral with a needle carrier (11),
• a supporting body (20), able to receive the needle carrier (11) in a removable manner and engageable to the fore end (2) of the syringe body (1),
• characterized in that it comprises
• elastic means (30) disposed under compression between said needle carrier (11) and said supporting body (20),
• a diaphragm (62) mounted in the head (51) of said shaft (50) to close an inner chamber formed axially in the body (56) of said shaft, said diaphragm being mounted removably or being breakable, and
• engagement means (60) provided in the head (51) of said shaft to cooperate with reciprocal engagement means (13) provided in said needle carrier (11) to cause disengagement of said needle carrier from said supporting body, when the plunger (40) reaches the end of the injection stroke, so that said elastic means (30) are released, causing retraction of said needle carrier which abuts against said diaphragm (62) causing disengagement or rupture thereof to allow entry of said needle carrier (11) into the chamber of the shaft body and carrying the needle (10) in a safety position.