| 摘要 |
A generally pen-like syringe incorporates a dose metering device provided by a cap (7) rotatable with respect to a pen body (8) to a position related to the dose of medicament (for example insulin) to be injected. The rotation compresses a coil spring (6), which is prevented from unwinding by co-operating ratchet teeth. When the dose is to be injected, a trigger slide (42) is moved to the left causing the ratchet teeth to come out of engagement. This permits the spring (6) to unwind, thereby rotating a drive sleeve (1), drive gear (3) and a drive plunger (2). The drive plunger (2) is formed with a quick pitch screw thread so that its rotational movement is accompanied by axial movement to cause medicament to be discharged from a cartridge and injected through a needle. |
