Automatic pen-type injector
First Claim
1. An injection device for causing a dose of liquid to be ejected, said device comprising:
- a housing;
a syringe located within said housing, the syringe comprising a container and a needle at one end of the container through which the dose of liquid is to be ejected;
a plunger, the syringe being movable by said 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 housing, the plunger having an end positioned within said container of the syringe; and
a surrounding and gripping flexible O-ring carried by said plunger, said O-ring rests against an enlarged head of the container, such that a primary movement of the plunger, under a bias of the actuating bias member, transmits a frictional force to the O-ring with the result that the container is moved by and with the O-ring linearly from said first to said second position, whereupon arresting of further movement of the container results in a frictional grip between the plunger and the O-ring being overcome, thus enabling the plunger to move by a secondary movement relatively to the O-ring, further into the container, into contact with and to act upon a plug within the container to compress the dose of liquid within the syringe and cause expression of the dose of liquid through the needle.
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
7 Claims
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1. An injection device for causing a dose of liquid to be ejected, said device comprising:
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a housing; a syringe located within said housing, the syringe comprising a container and a needle at one end of the container through which the dose of liquid is to be ejected; a plunger, the syringe being movable by said 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 housing, the plunger having an end positioned within said container of the syringe; and a surrounding and gripping flexible O-ring carried by said plunger, said O-ring rests against an enlarged head of the container, such that a primary movement of the plunger, under a bias of the actuating bias member, transmits a frictional force to the O-ring with the result that the container is moved by and with the O-ring linearly from said first to said second position, whereupon arresting of further movement of the container results in a frictional grip between the plunger and the O-ring being overcome, thus enabling the plunger to move by a secondary movement relatively to the O-ring, further into the container, into contact with and to act upon a plug within the container to compress the dose of liquid within the syringe and cause expression of the dose of liquid through the needle. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification