Patent ID: 8459253

Claim:
A dose counting device for use with a medicinal metered dose dispensing device and for converting movement of an actuator into rotational movement of an annular member, the device comprising an actuator having at least one finger that is designed for reciprocal movement comprising an outward stroke and a return stroke, an annular member having a helical thread segment formed about a circumferential arc on a part of its surface, and a drive nut positioned around a radial cross-section of the annular member and having an internal helical rib engaged with said helical thread segment on the annular member whereby rotation of the drive nut about the circumferential arc of the annular member results in rotational movement of the annular member, the outer surface of the drive nut comprising one or more driving surfaces for engagement by said at least one finger on the actuator during said reciprocal movement to cause rotation of the drive nut.