A drug delivery device is presented comprising of a housing, a plurality of contacts, and a cylindrical member configured to be rotatably supported inside the housing, wherein the outer surface of the cylindrical member is provided with a plurality of tracks together forming an encoder, each track comprising conductive segments and non-conductive segments, and wherein the cylindrical member is supported in the housing such that each track is engaged by a respective one of the plurality of contacts.ハウジングと；複数の接点（２１２）と；ハウジングの内部で回転自在に支持されるように構成された円筒状部材（４０６）の外面が、エンコーダを共に形成する複数のトラックを備え、各トラックは導電性セグメントおよび非導電性セグメントを備え、該円筒状部材は、各トラックが複数の接点のうちのそれぞれの接点によって係合されるようにハウジング内に支持される、該円筒状部材とを備える薬物送達デバイス。
