Automatic pen-type injector
1 Assignment
0 Petitions
Accused Products
Abstract
A syringe (1) is moved bodily forward by a plunger (7) (after release of a spring 8) by acting through an O-ring pressing onto an enlarged head (16) of a syringe container (3), in order to expose the needle (5) of the syringe before the plunger acts on a plug (4) within the syringe to cause the liquid to be ejected through the needle. There is, therefore, a two-step movement of the plunger, firstly together with the syringe through the medium of the O-ring, and secondly within the syringe container to force the plug forward, when a ledge (12) on the syringe container (3) is arrested by a stop (14), whereupon the frictional force between the plunger and the O-ring is relieved so that the plunger slides forward through the O-ring.
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Citations
13 Claims
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1-6. -6. (canceled)
- 7. An injection device for causing a dose of liquid to be ejected from the needle at one end of a syringe located within a housing of the device, the syringe being movable by a plunger, upon release of an actuating bias member at one end of the housing, to move the syringe, from a first position wherein the needle is shrouded by the housing, to a second position wherein the needle projects from the other end of the housing, the plunger having its free end positioned within the other end of a container of the syringe and carrying a surrounding and gripping flexible O-ring which rests against an enlarged head of the other end of the syringe container, such that a primary movement of the plunger, under the bias of the actuating bias member, will transmit a frictional force to the 0-ring with the result that the syringe container is moved by the O-ring from said first to said second position, whereupon arresting of further movement of the syringe container results in the frictional grip between the plunger and the O-ring being partially released, thus enabling the plunger to move by a secondary movement, into the syringe container, into contact with and to act upon a plug to compress the liquid within the syringe and cause expression of the liquid through the syringe needle.
Specification