Dose counter for a metered-dose inhaler

摘要

Disclosed herein is a dose counter for counting doses of medicament dispensed by or remaining in a metered-dose inhaler. The dose counter comprises a rotatably mounted gear wheel (130) having a circular arrangement of ratchet teeth (132) defining a root circle (134) and a display coupled to the gear wheel, the display having a visible array of dose counting indicia indexable in response to rotary motion of the gear wheel. The dose counter further comprises an actuator mechanism (118) having a driver (124) for rotatably driving the gear wheel in response to the dispensation of a medicament dose, the driver being arranged to engage the ratchet teeth of the gear wheel. The actuator mechanism includes an actuator shaft (120) mounted for linear movement in response to the dispensing of a dose of medicament and an engagement arm (122) pivotally mounted to the actuator shaft and carrying the driver. The actuator shaft and the engagement arm are configured such that, in use of the dose counter for counting a dispensed dose, the travel of the driver along the root circle of the gear wheel exceeds the corresponding linear movement of the actuator shaft.