Dose counter for a metered-dose inhaler

摘要

Disclosed herein is a dose counter (118) 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); 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; and an actuator mechanism having a driver (152) 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 comprises a pivotally mounted lever or linkage having an input portion. The lever or linkage is arranged to amplify a linear stroke at the input portion such that a linear stroke of the driver exceeds the linear input stroke. By amplifying the stroke in this way, the risk of undercounting due to insufficient stroke length may, be reduced.