Claims for Patent: 6,446,627

Summary for Patent: 6,446,627

Title:	Inhaler dose counter
Abstract:	A dose counter for a metered dose inhaler comprises actuator means (341), drive means (350) for driving a rotary gear (360) in step-wise fashion in response to displacement of said actuator means (341), said rotary gear (360) comprising a wheel having a plurality of ratchet teeth (not shown) around its periphery. Means (364) are provided to prevent reverse rotation of the rotary gear (360). A flexible tape (368) is provided with a visible array of incrementing integers on its surface indicating the number of medicament doses remaining in the inhaler. The tape (368) indexes by a single integer in response to each step of the step-wise rotary motion of the rotary gear (360). A control surface (371) regulates the position of engagement and disengagement between the drive means (350) and the rotary gear (360). In an alternative embodiment (FIG. 6), the control surface (371) is omitted and the means for preventing reverse rotation comprise a stepless restraint (664).
Inventor(s):	Bowman; Nicholas John (Royston, GB), Holroyd; Michael John (Great Shelford, GB), Panayi; Costaninos (Royston, GB), Treneman; William Richard (Oakington, GB)
Assignee:	Norton Healthcare Limited (London, GB)
Application Number:	09/319,947
Patent Claims:	1. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of said wheel; drive means for driving said rotary gear means in step-wise fashion in response to displacement of said actuator means; reverse rotation prevention means to prevent reverse rotation of said rotary gear means; display means coupled to said rotary gear means, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and a control surface to regulate a position of engagement and disengagement between said drive means and said wheel, wherein the reverse rotation prevention means is a friction clutch. 2. A dose counter as claimed in claim 1 wherein the friction clutch is a wrap-spring clutch. 3. A dose counter as claimed in claim 1 wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms. 4. A dose counter as claimed in claim 1 wherein the display means is an elongate flexible web on which a dose count is printed or written. 5. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of said wheel; drive means for driving said rotary gear means in step-wise fashion in response to displacement of said actuator means; display means coupled to said rotary gear means, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and stepless restraint means to prevent reverse rotation of said rotary gear means, wherein the stepless restraint means is a wrap-spring clutch operating on the spindle on which the wheel is mounted and bracing the spindle against reverse rotation. 6. A dose counter as claimed in claim 5 wherein the actuator means are operable by linear displacement from a first position to a second position and back to said first position and wherein a count index occurs either during a forward stroke of the actuator means from said first position to said second position or during a return stroke of the actuator means from said second position to said first position. 7. A dose counter as claimed in claim 6 wherein the actuator means comprise a spring-loaded plunger adapted to engage a rim of a medicament reservoir, said plunger being depressible against the return force of the spring loading when the medicament reservoir is translated to deliver a dose of medicament through a metering valve. 8. A dose counter as claimed in claim 5 wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms. 9. A dose counter as claimed in claim 5 wherein the display means is an elongate flexible web on which a dose count is printed or written. 10. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of said wheel; drive means for driving rotary gear means in step-wise fashion in response to displacement of said actuator means; display means coupled to, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and a ratchet and drive pawl mechanism including a rack having an array of ratchet teeth and drive pawl means in the form of a straddle drive in which an element that engages the ratchet teeth of the rack is supported between a pair of spaced apart support arms. 11. A dose counter as claimed in claim 10 wherein a gap between the support arms is dimensioned to accommodate a thickness of the rack therebetween. 12. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of said wheel; drive means for driving said rotary means in step-wise fashion in response to displacement of said actuator means; reverse rotation prevention means to prevent reverse rotation of said rotary gear means; display means coupled to said rotary gear means, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and a control surface to regulate a position of engagement and disengagement between said drive means and said wheel, wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms. 13. A dose counter as claimed in claim 12 wherein the actuator means are operable by linear displacement from a first position to a second position and back to said first position and wherein a count index occurs either during a forward stroke of the actuator means from said first position to said second position or during a return stroke of the actuator means from said second position to said first position. 14. A dose counter as claimed in claim 13 wherein the actuator means comprises a spring-loaded plunger adapted to engage a rim of a medicament reservoir, said plunger being depressible against the return force of the spring loading when the medicament reservoir is translated to deliver a dose of medicament through a metering valve. 15. A dose counter as claimed in claim 12 wherein the reverse rotation prevention means is a friction clutch. 16. A dose counter as claimed in claim 15 wherein the friction clutch is a wrap-spring clutch. 17. A dose counter as claimed in claim 12 wherein the display means is an elongate flexible web on which a dose count is printed or written. 18. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of said wheel; drive means for driving said rotary gear means in step-wise fashion in response to displacement of said actuator means; reverse rotation prevention means to prevent reverse rotation of said rotary gear means; display means coupled to said rotary gear means, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and a control surface to regulate a position of engagement and disengagement between said drive means and said wheel, wherein the display means is an elongate flexible web on which a dose count is printed or written. 19. A dose counter as claimed in claim 18 wherein the actuator means are operable by linear displacement from a first position to a second position and back to said first position and wherein a count index occurs either during a forward stroke of the actuator means from said first position to said second position or during a return stroke of the actuator means from said second position to said first position. 20. A dose counter as claimed in claim 19 wherein the actuator means comprises a spring-loaded plunger adapted to engage a rim of a medicament reservoir, said plunger being depressible against the return force of the spring loading when the medicament reservoir is translated to deliver a dose of medicament through a metering valve. 21. A dose counter as claimed in claim 18 wherein the reverse rotation prevention means is a friction clutch. 22. A dose counter as claimed in claim 21 wherein the friction clutch is a wrap-spring clutch. 23. A dose counter as claimed in claim 18 wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms. 24. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of a wheel; drive means for driving said rotary gear means in step-wise fashion in response to displacement of said actuator means; display means coupled to, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and stepless restraint means to prevent reverse rotation of said rotary gear means, wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms. 25. A dose counter as claimed in claim 24 wherein the stepless restraint means is a wrap-spring clutch operating on the spindle on which the wheel is mounted and bracing the spindle against reverse rotation. 26. A dose counter as claimed in claim 25 wherein the actuator means comprise a spring-loaded plunger adapted to engage a rim of a medicament reservoir, said plunger being depressible against the return force of the spring loading when the medicament reservoir is translated to deliver a dose of medicament through a metering valve. 27. A dose counter as claimed in claim 24 wherein the actuator means are operable by linear displacement from a first position to a second position and back to said first position and wherein a count index occurs either during a forward stroke of the actuator means from said first position to said second position or during a return stroke of the actuator means from said second position to said first position. 28. A dose counter as claimed in claim 24 wherein the display means is an elongate flexible web on which a dose count is printed or written. 29. A dose counter for a metered dose inhaler, the counter comprising: actuator means; rotary gear means having a wheel mounted on a spindle, said wheel having a plurality of ratchet teeth around a periphery of a wheel; drive means for driving said rotary gear means in step-wise fashion in response to displacement of said actuator means; display means coupled to said rotary gear means, said display means having a visible array of incrementing integers on a surface thereof indexable by a single integer in response to each step of the step-wise motion of the rotary gear means; and stepless restraint means to prevent reverse rotation of said rotary gear means, wherein the display means is an elongate flexible web on which a dose count is printed or written. 30. A dose counter as claimed in claim 29 wherein the stepless restraint means is a wrap-spring clutch operating on the spindle on which the wheel is mounted and bracing the spindle against reverse rotation. 31. A dose counter as claimed in claim 29 wherein the actuator means are operable by linear displacement from a first position to a second position and back to said first position and wherein a count index occurs either during a forward stroke of the actuator means from said first position to said second position or during a return stroke of the actuator means from said second position to said first position. 32. A dose counter as claimed in claim 31 wherein the actuator means comprise a spring-loaded plunger adapted to engage a rim of a medicament reservoir, said plunger being depressible against the return force of the spring loading when the medicament reservoir is translated to deliver a dose of medicament through a metering valve. 33. A dose counter as claimed in claim 29 wherein the drive means comprises a ratchet drive pawl in the form of a straddle drive in which an engagement element that engages the ratchet teeth of the wheel is supported between a pair of spaced apart support arms.