Patent ID: 7824381

Claim:
A safety disposable syringe comprising: (a) a barrel comprising front and rear open ends and defining a chamber therein and an axis, said barrel being formed with an inner shoulder adjacent to said front open end; (b) a plunger extending through said rear open end and into said chamber, and comprising a front end; (c) a piston mounted on said front end of said plunger and formed with a first engaging member; (d) a cannula; (e) a needle seat extending fittingly through said front open end of said barrel and comprising (i) a front seat portion that has a front end disposed outwardly of said chamber, and that defines a central channel extending through said front end of said front seat portion for extension of said cannula thereinto, and (ii) a rear seat portion that is disposed in said chamber, and that extends away from said front seat portion to terminate at a rear surface confronting said piston, said rear seat portion having an outer surface that surrounds the axis and that is in frictional contact with an inner surface of said front open end of said barrel, said outer surface defining an annular retaining groove that is disposed proximate to said front seat portion; (f) an engaging flange extending radially and outwardly from said rear surface, and configured to abut against said inner shoulder of said barrel axially; wherein said rear seat portion defines a fluid passage comprising: (i) a radially extending section that communicates with said central channel, and that extends outwardly through said outer surface so as to communicate with said inner surface of said front open end of said barrel, said radially extending section being disposed below and separated from said annular retaining groove by a partition region that borders said radially extending section, and (ii) at least one axially extending section that is formed in said rear surface adjacent to said engaging flange, that extends axially towards said front seat portion and along said outer surface to communicate with said radially extending section, and that terminates at said partition region; (g) a second engaging member disposed on said rear surface, and axially aligned and engageable with said first engaging member; and (h) a sealing ring retained in said retaining groove and in sealing contact with said inner surface of said front open end of said barrel, wherein said radially extending section of said fluid passage has opposite ends, which are at the opposite sides of said central channel, and which extend outwardly through said outer surface of said rear seat portion of said needle seat respectively, said fluid passage having a pair of axially extending sections extending axially towards said front seat portion of said needle seat along said outer surface to communicate respectively with said opposite ends of said radially extending section and terminating at said partition region.