IMPROVEMENTS IN AND RELATING TO AN INJECTION DEVICE
Injection devices are known for the self administration of a medicament by patients. The medicament is typically contained within a cartridge located within an injection device. It is a problem that injection devices should be small enough to fit into a jacket pocket or a hand bag without difficulty. Concurrently, the injection device must be of a size that enables a piston used to drive a cartridge bung within the cartridge to both to a maximum dispense position within the cartridge and to be fully withdrawn from the cartridge to allow for replacement of the cartridge. A drive mechanism for an injection device is disclosed comprising a piston member (10), a semi rigid belt (12) connected at a first end to the piston member (10), a belt drive means to drive the semi rigid belt (12) and a dose setting mechanism to control the driving of the semi rigid belt (12) in which the belt drive means comprises a first cable means (22) connected at a first end to a second end of the semi rigid belt (12) and at a second end to a first spool (24). An injection device comprising such a drive mechanism is also disclosed.