Patent ID: 6110149
Filing Date: 2000-08-29
Classification: A61M

Abstract:
A syringe comprising a housing for receiving an ampoule containing a medicine, a dose setting and injection mechanism, and an air shot dispensing mechanism, wherein said dose setting and injection mechanism comprises:a stop member supported in said housing;a dose setting member which is supported in said housing for movement in a first direction away from said stop member and a second direction towards said stop member, wherein said dose setting member may be moved in said first direction to one of a plurality of selectable positions in order to set the amount of the dose to be dispensed;a piston rod moveably supported in said housing for acting on a piston in an ampoule; anda unidirectional coupling mechanism between said dose setting member and said piston rod for transmitting movement of said dose setting member only in said second direction; wherein said dose setting member, after being moved in said first direction to set a dose, may be moved in said second direction until reaching said stop member, and wherein such movement of said dose setting member in said second direction causes said piston rod to move forward a distance proportional to the set dose to expel said set dose from an ampoule; andwherein said air shot dispensing mechanism comprises:an air shot button; andan air shot coupling mechanism between said air shot button and said dose setting and injection mechanism for permitting said piston rod to move forward, by a predetermined distance, when said air shot button is actuated, without first setting a dose.