Dose counters for inhalers and method of designing an incremental dose counter

摘要

A manually operated measured dose inhaler (12) includes a dose counter chamber (66) including a dose display tape (112) driven by a ratchet wheel (94) which is driven in turn by an actuator pawl (80), actuated by movement of a canister (20); two-step ribs (144, 146) being provided to prevent rocking of the canister (20); a drain hole (194) being provided for preventing misting of a display window (118); and frictional surfaces (132, 134) being provided on a shaft (108) of a tape stock bobbin (110) to prevent tape slippage; a rotation regulator being provided for the stock bobbin and comprising a wavelike engagement surface (300) with concavities (302) which engage against control elements (128, 130) in the form of protrusions on resilient forks of a split pin (108) thereby permitting incremental unwinding of the stock bobbin yet resisting excessive rotation if the inhaler is dropped onto a hard surface.