Abstract: A drug delivery device comprising: a housing; a plurality of sensors; and a cylindrical member supported within the housing, an outer surface of said cylindrical member being provided with a helical track, the helical track comprising track segments of a first type and track segments of a second type, the first and second types of track segments being respectively capable of inducing first and second responses in the sensors; wherein: the helical track has a width; the helical track includes across the width of the helical track at least one track segment of the first type and at least one track segment of the second type at plural positions along a length of the helical track; the device is configured such that during a first phase of a drug delivery operation the helical track is moved axially, without rotation, relative to the plurality of sensors between a first position and a second position, and during a second phase of the drug delivery operation the track is moved helically relative to the plurality o

Abstract: A drug delivery device comprising: a housing; a plurality of sensors; and a cylindrical member supported within the housing, the outer surface of said cylindrical member being provided with a helical track, the helical track comprising track segments of a first type and track segments of a second type, the first and second types of track segment being respectively capable of inducing first and second responses in the sensors; wherein: the helical track has a width dimension W; the helical track includes across its width at least one track segment of the first type and at least one track segment of the second type at plural positions along the length of the helical track; the device is configured such that during a first phase of a drug delivery operation the helical track is moved axially, without rotation, relative to the plurality of sensors between a first position and a second position, and during a second phase of the drug delivery operation the track is moved helically relative to the plurality of senso

Abstract: A drug delivery system comprises a drug delivery device which comprises a housing and a cartridge. The drug delivery device has a proximal end and a distal end. The drug delivery system further comprises a needle assembly which is attachable to the drug delivery device. The needle assembly and the drug delivery device are configured such that the cartridge is moved in the proximal direction with respect to the housing when the needle assembly is attached to the drug delivery device.