| 摘要 |
<p>A disposable, automatic, injector is disclosed which allows self-administration of a medicament to be injected subcutaneously. The injector comprises a barrel (1) with an inner chamber bounded by a liner (2). A first piston (4) and a second piston (11) are provided which may slide within the chamber with a fluid-tight seal with the liner (2). The second piston (11) carries an injection needle (13). A drive means, comprising a compression spring (5) and a releasable retaining collet (6), is provided to act on the first piston (4) to drive it towards the second piston (11). In operation, the drive means urges the first piston towards the second (11). The injection fluid, initially stored between the first and second pistons is incompressible and causes the second piston (11) to move until the needle (13) projects from the end of the barrel (1). When the needle (13) is fully extended the second piston (11) stops but the first piston (4) continues to move so causing injection fluid to be forced out through the needle (13).</p> |
