PEN TYPE DRUG INJECTION DEVICE WITH FRICTION REDUCING DOSE ENCODER MECHANISM

摘要

A pen-type drug injection device comprises a housing (102) having a longitudinal axis, an axially moveable component that is moveable along the longitudinal axis between a dose dialling position and a dose delivery position when a user operates the device to deliver a dose of drug, an encoder sleeve (406) carrying an encoder pattern comprising relatively conductive portions and relatively non-conductive portions (302,304) that together comprise coded dosage information, and a sensor sleeve (310) carrying several electrical contacts (312). The electrical contacts contact the encoder pattern (300) when the dose delivery button is in the dose dialling position and the device is configured to move the sensor sleeve relative to the encoder sleeve as the axially moveable component moves from the dose dialling position to the dose delivery position such as to move the electrical contacts into positions where they do not contact the encoder pattern in order not to produce additional friction during the injection.