Patent ID: 7104969

Claim:
A safety syringe comprising: a cylindrical chamber having a front end that includes a discharge end; a plunger slidably coupled to said cylindrical chamber; a needle holder structured to receive a needle having at least a portion of which that protrudes from said discharge end; a cylinder unit slidably arranged within said front end; a plunger seal coupled to said plunger which is arranged for movement relative to said plunger after medicament discharge; and said plunger being arranged to slidably move said cylinder unit toward said discharge end and to slidably dislodge said plunger seal, wherein said cylinder unit is structured to provide a protective shield around the portion of the needle protruding from said discharge end, wherein a space is formed within said plunger comprising a first and a second cylindrical space, said first and second cylindrical spaces having different diameters and being coupled to each other to form a step change, and wherein said plunger comprises an aperture positioned before said step change, in a plunger seal movement direction, said aperture being formed in the cylinder space having the smaller diameter.