U.S. patent application number 17/010073 was filed with the patent office on 2021-01-21 for dose indicator or dose counter.
The applicant listed for this patent is KINDEVA DRUG DELIVERY L.P.. Invention is credited to Stephen J. Howgill, Adam J. Stuart.
Application Number | 20210016025 17/010073 |
Document ID | / |
Family ID | 1000005120623 |
Filed Date | 2021-01-21 |
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United States Patent
Application |
20210016025 |
Kind Code |
A1 |
Stuart; Adam J. ; et
al. |
January 21, 2021 |
DOSE INDICATOR OR DOSE COUNTER
Abstract
A dose indicator or dose counter is disclosed which includes an
indexable first display unit indexable about a first display axis,
an indexable second display unit indexable about a second display
axis, the second display axis being transverse to the first display
axis, and a chassis comprising a chassis frame, a displacement
portion comprising a drive means to engage the first display unit,
and at least one hinge means directly or indirectly connecting the
displacement portion and chassis frame. The drive means is
preferably configured to index the dose indicator. The dose
indicator/counter has a small number of components yet is
effective, reliable and compact.
Inventors: |
Stuart; Adam J.;
(Loughborough, GB) ; Howgill; Stephen J.;
(Leicestershire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KINDEVA DRUG DELIVERY L.P. |
St. Paul |
MN |
US |
|
|
Family ID: |
1000005120623 |
Appl. No.: |
17/010073 |
Filed: |
October 6, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14904321 |
Jan 11, 2016 |
10792444 |
|
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PCT/US2014/045694 |
Jul 8, 2014 |
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17010073 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 15/009 20130101;
G06M 1/042 20130101; G06M 1/04 20130101; A61M 15/0073 20140204;
A61M 15/0075 20140204 |
International
Class: |
A61M 15/00 20060101
A61M015/00; G06M 1/04 20060101 G06M001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 2013 |
GB |
1312448.2 |
Claims
1. A dose indicator comprising, an indexable first display unit
indexable about a first display axis, an indexable second display
unit indexable about a second display axis, the second display axis
being transverse to the first display axis, and a chassis
comprising a chassis frame, a displacement portion comprising a
drive member to engage the first display unit, and at least one
hinge directly connecting the displacement portion and chassis
frame.
2-36. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to United Kingdom
Application No. 1312448.2, filed Jul. 11, 2013, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] The present specification relates to dose indicators or dose
counters, and more particularly to dose indicators or dose counters
for pressurised metered dose inhaler (pMDI) devices. The present
invention also relates to actuators comprising such dose
indicators/counters and to inhalers comprising such actuators.
[0003] Patients who use inhalers, such as pMDI devices, need to
monitor their inhaler usage, and regulators of medicines have begun
to require that some method of dose indication is included into the
inhaler. Dose counters (providing a precise count of the number of
doses remaining) and dose indicators (providing an indication of
the number of doses remaining) for inhalers are known.
[0004] In most dose counters and dose indicators, the display is
indexed each time the inhaler device is used. Many dose counters
and/or dose indicators are complex, requiring a number of small
mechanical parts, which may increase cost, may lead to difficulties
in assembly, and may require tight dimensional tolerances.
[0005] International Publication No. WO 2011/071788 discloses dose
counters for dispensers and in particular dose counters for use
with metered dose inhalers.
[0006] U.S. Pat. No. 6,752,153 discloses an inhaler for
aerosolization of medicament with a dose counter. The dosage
counter has a first and a second counting ring and a coupling
device that connects the counting rings.
[0007] International Publication No. WO 1998/52634 discloses a
dosing device and in particular relates to dosing devices for drug
delivery such as injectors and inhalers and a mechanism for use in
such devices.
[0008] It would be advantageous to provide a dose indicator or dose
counter that has fewer essential parts. It would also be
advantageous if the dose indicator were designed to fit within
typical existing pMDI actuators and to be compatible with existing
pMDI valves.
[0009] In this specification, the term "dose indicator" is intended
to refer to both dose counter devices and dose indicator
devices.
SUMMARY
[0010] In a first aspect, there is provided a dose indicator
comprising, an indexable first display unit indexable about a first
display axis, an indexable second display unit indexable about a
second display axis, the second display axis being transverse to
the first display axis, and a chassis comprising a chassis frame, a
displacement portion comprising a drive means to engage the first
display unit, and at least one hinge means directly or indirectly
connecting the displacement portion and chassis frame. The drive
means is preferably configured to index the dose indicator.
[0011] This is advantageous because it provides a dose
indicator/counter that has a small number of components yet is
effective, reliable and compact. Furthermore, the invention allows
the provision of a cheap, simple and reliable dose-by-dose counter
that is capable of counting 200 doses or puffs. It may count down
from 200 to 0 and is able to fit within a pMDI actuator of similar
shape and comparable size to existing actuators.
[0012] The hinge means (e.g. hinge or hinges) may generally be any
connecting portion including such that allows restricted but
controlled relative movement of the displacement portion and the
chassis frame, including relative rotational and/or translational
movement.
[0013] The second display axis and the first display axis may be
arranged so that they do not intersect. However, generally the
second display axis will intersect the first display axis.
[0014] The second display axis may, preferably, be at an acute or
an obtuse angle to the first display axis. In some circumstances,
the second display axis may be substantially orthogonal to the
first display axis.
[0015] Generally, the first display unit and/or the second display
unit will be substantially circular in a cross-section (usually a
cross section transverse, preferably generally orthogonal, to the
first and/or second display axis respectively) and will be
rotatably indexable about the first display axis and/or about the
second display axis respectively. The term "substantially circular"
in this context includes annular or disc-shaped embodiments and
polygonal shapes with at least five sides.
[0016] The drive means is preferably adapted to engage the first
display unit. In particular, it is preferred if the drive means is
adapted to engage the first display unit on a curved path, the
drive means being driven by a force from outside the circumference
of the first display unit. This improves the stability of indexing
because it allows freer movement of the drive means past the first
display unit and reduces the risk of advancing an additional,
unwanted count.
[0017] Thus, in a second aspect, there is provided a dose indicator
comprising, an indexable first display unit rotatably indexable
about a first display axis, and a chassis comprising a chassis
frame, a displacement portion comprising a drive means to engage
the first display unit, and at least one hinge means directly or
indirectly connecting the displacement portion and chassis frame,
wherein the drive means is adapted to engage the first display unit
on a curved path, the drive means being driven by a force from
outside the circumference of the first display unit. Optionally
there is also an indexable second display unit, indexable about a
second display axis.
[0018] Preferably, the first display unit is rotatable in a first
plane transverse to the first display axis, and the curved path is
at least partly outside the first plane. It is also preferred that
the drive means is driven by a force that has a component generally
in the first plane, the component of the force that is in the first
plane being outside the circumference of the first display unit.
This is advantageous because it allows that the first display unit
may be of generally disc-like or polygonal (5 sides or greater)
cross section with the indexing features (e.g. indexing teeth)
being on the outer circumference of the unit.
[0019] Preferably, the drive means is angled into the first display
unit to improve engagement and to reduce the chance of the drive
means unintentionally disengaging from the first display unit.
[0020] Preferably, the chassis is moulded as a unitary piece.
Preferably, the first display unit is also moulded as a unitary
piece. It is also preferred if the second display unit is moulded
as a unitary piece. This is advantageous because it enables the
reduction of the number of parts of the dose indicator, with
consequent benefits of cost and simplicity of assembly. The
components of the dose indicator may therefore number just three
corresponding to chassis, first display unit and second display
unit. However, in some circumstances additional components may be
advantageous.
[0021] It is preferred if the chassis, first display unit and
second display unit are each independently designed so they may be
injection moulded without the requirement for a side action in the
moulding tool. This reduces flash in the moulded components.
[0022] It is preferred if the drive means is integrally comprised
in the displacement portion.
[0023] In preferred embodiments, the drive means comprises a drive
pawl. In some embodiments it is advantageous if the engaging end of
the drive pawl is outside the cylindrical envelope of the first
display unit (i.e. outside its circumference) in the rest position,
and is brought within this envelope during actuation. Thus, during
actuation preferably the drive pawl follows a path from outside the
circumference of the first display unit.
[0024] Usually, the displacement portion will be adapted so that it
may be displaced along a displacement path that is preferably at
least partly transverse to the first display axis. It is preferred
if the displacement path is at least partly arcuate. This may be
achieved, for example, if the drive means is located on the
displacement portion at a position remote from the hinge or hinges,
preferably at a position distal to the hinge or hinges. The hinges
may be configured for substantially pivotal (rotational) movement
of the displacement portion.
[0025] Usually, the displacement portion will comprise at least one
press member that acts as an interference portion for interference
with the valve during actuation. The press member or members may
for example be a press knuckle or press knuckles. It is
advantageous if the contact points (e.g. press knuckles) between
the valve and the displacement portion include points that are
radially in different directions from the valve stem, as this helps
to compensate for effects of the patient tilting the canister
slightly during actuation. Thus, preferably there are two or more
contact points (e.g. press knuckles) distributed on the
displacement portion.
[0026] The dose indicator will usually further comprise at least a
first display non-return means, the first display non-return means
being preferably at least partly located on the chassis frame. The
non-return means may be for example a frictional non-return means,
but in a preferred embodiment the first display non-return means
comprises a non-return arm adapted to interact with one or more
detents on the first display unit.
[0027] The chassis preferably further comprises at least one return
means. The return means will usually comprise at least one spring.
Preferably, the at least one spring comprises a leaf spring,
preferably a curved leaf spring. The at least one return means
(preferably a curved leaf spring) will usually directly or
indirectly connect the displacement portion and chassis frame,
preferably at a position remote from the hinge or hinges.
[0028] Usually, the first and/or the second display unit will be
adapted to index through between 5 and 25 indicia, preferably 8 to
12 indicia.
[0029] The dose indicator may comprise a first display unit
mounting means for mounting the display unit on the chassis frame
so that it is indexable about the first display axis.
[0030] The internal profile of the first display unit may include
an axle bearing and the chassis may include an axle with an
external profile designed to engage closely with the axle bearing
to allow relative rotational movement without wobble. This may be
achieved by close circumferential engagement of the internal
profile of the first display unit and the external profile of the
first display unit axle over most of the circumference
corresponding to positions on the first display unit axle that are
axially separated by some distance. This distance is preferably
greater than the thickness of the portion of the first display unit
that bears indicia.
[0031] The first display unit axle may be substantially
cylindrical, or it may have cylindrical sections of different
diameter. For example the section closer to the first display
unit's indicia may have the larger diameter. The first display unit
axle may have a lead-in surface at the distal end to facilitate
placing of the first display unit. This first display unit axle may
be configured to hold the first display unit in position and to
prevent its axial translation along the first display unit axle,
e.g. by the provision of circumferential detents.
[0032] Usually, in embodiments of the invention, the first display
unit is a units display unit.
[0033] Preferably, the second display unit is a tens display
unit.
[0034] In preferred embodiments the first display unit comprises a
drive arm adapted to index the second display unit. This is
particularly suited to embodiments in which the second display unit
is a tens display unit.
[0035] An angled edge may be provided on the trailing side of the
drive arm and/or the indexing teeth of the second display unit may
be provided with angled leading edges. This reduces the chances of
a double second (e.g. tens) count occurring whilst maximizing the
overlap between the drive arm and indexing teeth. A rounded leading
edge may be provided on the leading edge of the drive arm. This
ensures that the point contact with an indexing tooth has a high
incident angle for most of an indexing movement of the second
display unit.
[0036] In some embodiments the first display unit has a
substantially circular cross section, preferably a cross section on
a plane transverse (more preferably substantially orthogonal) to
the first display axis.
[0037] In some embodiments the second display unit has a
substantially circular cross section, more preferably a
substantially annular cross section. It is preferred if the cross
section is on a plane transverse (more preferably substantially
orthogonal) to the second display axis.
[0038] In preferred embodiments, the first and/or the second
display unit comprises a zero stop means. It is particularly
preferred that the second display unit comprises a zero stop means
to stop the second display unit from advancing beyond the zero
count (e.g. of ten if the second display units is a tens display
unit) corresponding to a nearly empty inhaler, and the second
display unit is preferably further configured to prevent indexing
of the first display unit beyond the ensuing zero units count. This
configuration of the stop means may be achieved by using positive
engagement between the first (e.g. the units) display unit and the
second (e.g. tens) display unit. In embodiments where the first
and/or the second display unit comprises a zero stop means, the
drive member may be configured to deflect or collapse to allow
continued use of the inhaler after the displayed overall count has
reached zero.
[0039] Preferably, the zero stop means interacts with a stop arm
located on the chassis.
[0040] Advantageously, the chassis comprises polyoxymethylene (i.e.
POM, acetal). The polyoxymethylene is preferably in homopolymer
form.
[0041] In a third aspect, the invention provides an actuator for an
inhaler, the actuator comprising a dose indicator as discussed in
the first or second aspect.
[0042] In a fourth aspect, the invention provides an inhaler
comprising an actuator as discussed in the third aspect.
[0043] The dose indicator of the present invention is of simple
construction, whilst being robust and reliable in its indication of
doses. It is suitable for use in a pressurized metered dose inhaler
(pMDI) or other dispensing devices (e.g. dry powder inhalers,
aqueous pump dispensers) to indicate usage (e.g. number of doses
used or number of doses remaining) by means of numbers and/or
coloured regions or other indicia in its display. Typically doses
are counted downwards, and an indication of when the inhaler
canister needs to be replaced may be provided in addition to an
indication of the number of doses that have been dispensed.
[0044] When adapted for a pMDI, the dose indicator may be of a
suitable size and configuration to fit into existing inhaler
actuators, including breath actuated actuators or actuators with
breath coordination means incorporated, without appreciable changes
to the dimensions or shape of the existing actuator designs.
Actuators will typically be provided with a window for viewing the
dose indication or count.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] So that the present specification may be more completely
understood, reference is made to the accompanying drawings in which
like elements are given like reference numerals (with the addition
of 100 or multiples of 100 to the numerals of different
embodiments):
[0046] FIG. 1 shows a bottom perspective view of an exemplary dose
indicator.
[0047] FIG. 2 shows a top perspective view of a chassis of the dose
indicator of FIG. 1.
[0048] FIG. 3 shows a bottom perspective view of the chassis of the
dose indicator of FIG. 1.
[0049] FIG. 4 shows a side perspective view of the units display
unit of the dose indicator of FIG. 1.
[0050] FIG. 5 shows a reverse side perspective view of the units
display unit of the dose indicator of FIG. 1.
[0051] FIG. 6 shows a bottom perspective view of the tens display
unit of the dose indicator of FIG. 1.
[0052] FIG. 7 shows a side view of the dose indicator of FIG. 1,
illustrating its operation.
[0053] FIG. 8 shows a perspective view of a second exemplary dose
indicator.
[0054] FIG. 9 shows a bottom perspective view of a third exemplary
dose indicator.
[0055] FIG. 10 shows another bottom perspective view of the third
exemplary dose indicator.
[0056] FIG. 11 shows a top view of the third exemplary dose
indicator
[0057] FIGS. 12a and 12b show vertical cross sections, taken
centrally through the back and front of each dose indicator, of the
dose indicator of FIGS. 1 to 7 and a similar, alternative
embodiment respectively.
[0058] FIG. 13 shows a cross section through a pressurised metered
dose inhaler incorporating a dose indicator as illustrated in FIGS.
10 and 11.
DETAILED DESCRIPTION
[0059] This invention relates to a two-component (with an optional
third component) dose indicator for a pMDI. The indicator may be
indexed by the displacement generated when a patient actuates a
pMDI valve.
[0060] In the embodiment illustrated in FIGS. 1 to 7, the dose
counter 1 comprises a dose-by-dose counter for a pMDI (that is
capable of being configured to count down from 200 to 0) which
comprises a chassis 2, a units display unit 33 and an optional tens
display unit 42. The dose counter 1 can be inserted into a standard
pMDI actuator.
[0061] As shown in FIG. 1 and FIG. 7, a dose counter 1 comprises a
chassis 2 with a chassis frame 4 of generally annular form. The
annular form of the chassis frame 4 is designed to fit snugly into
an inhaler actuator to provide support and to prevent deformation
in use. Optionally the support may be enhanced by one or more
ledges on the actuator for seating a horizontal surface of the
chassis, or ribs/grooves to prevent deformation and relative
rotation of the chassis frame in the actuator. The chassis 2
incorporates a number of features including springs, hinges and
indexing features that are used to actuate and reset the device.
The features are formed integrally (i.e. moulded in a unitary
piece) with the chassis 2.
[0062] The dose counter 1 also comprises a units display unit 33
that comprises a units display unit boss 41 and a series of units
display unit indexing teeth 38. A drive pawl 6 formed integrally
with the chassis 2 contacts the indexing teeth 38 and indexes the
teeth when chassis 2 is pressed against by a valve of a medicament
canister pressing downwards on indexing knuckles 26 (not visible in
FIG. 1; see FIG. 2) on the top side of the chassis 2. When pressed
downwards, the displacement plate 19 (see FIG. 2) of the chassis 2
moves downwards and hinges 20, integrally formed with the chassis
frame 4 and displacement plate 19, deform. Spring arms 12 return
the chassis 2 to its original position after indexing.
[0063] A non-return arm 8 also formed integrally with the chassis 2
contacts a series of non-return teeth 40 arranged coaxially with
the indexing teeth 38, and prevents backwards movement of the units
display unit 33. A units display unit stop arm 32 integrally formed
with the chassis 2 is positioned adjacent to the units display unit
boss 41 and guards against the units display unit 33 jumping off
its mounting.
[0064] The dose counter 1 also comprises an optional tens display
unit 42 in the form of a ring with tens display unit indexing teeth
46 indexed by the tens display unit drive tooth 39 (not visible in
FIG. 1; see FIG. 7) and generally prevented from backwards movement
by the tens display unit non-return arm 28.
[0065] Lugs 22 reduce rotation of the dose counter 1 when mounted
in the actuator in such a way as to allow the stem post of the
actuator to pass through stem post aperture 14.
[0066] FIGS. 2 and 3 show the chassis 2 from a top view and a side
bottom view respectively. In addition to the features visible in
FIG. 1, the chassis 2 comprises indexing knuckles 26 (see FIG. 2)
that are contacted by the valve of a medicament canister when it is
displaced downwards to actuate the metered dose valve to dispense a
metered dose. As discussed above, upon actuation the displacement
plate 19 moves downwards and the hinges 20 deform. The spring arms
12 are resilient and resist displacement and return the
displacement plate 19 to its original position after actuation.
[0067] Thus, an indexing element is attached to a displacement
plate 19 that is anchored to a chassis frame 4 at one end by two
hinges and at the other end by two spring arms 12 that are also
anchored to the chassis frame 4. The two spring arms 12 have a long
active length in order to reduce stress concentration. This is
advantageous because it reduces strain in the springs over
time.
[0068] Having the spring arms 12 separate from the hinges is also
advantageous, as each feature is only required to perform a single
function.
[0069] In alternative embodiments, the hinges could be used to
provide the spring force, but due to a short active spring length
the stresses and strain in the hinges would be higher.
[0070] In an alternative embodiment, the hinge means may be
provided by one or more springs.
[0071] The units display unit 33 is mounted on the units display
unit axle 18, which is angled at an acute angle with respect to the
chassis 2 to take account of the arcuate movement of the drive pawl
6 owing to its position distal to the hinges 20 on the displacement
plate 19. The chassis frame 4 includes tens display unit clips 10
and tens display unit locating ledge 24 to mount the tens display
unit 42, and zero stop arm 16.
[0072] FIGS. 4 and 5 show the units display unit 33. The units
display unit 33 is generally circular in end view and comprises two
coaxial sets of gear teeth: units display unit indexing teeth 38
and units display unit non-return teeth 40. The units display unit
indexing teeth 38 interact with the drive pawl 6 when the units
display unit 33 is mounted on the chassis 2. The units display unit
non-return teeth 40 interact with the non-return arm 8 when the
units display unit 33 is mounted on the chassis 2, thereby
preventing return of the units display unit 33 after an indexing
stroke.
[0073] The profiles of the indexing teeth 38 and non-return teeth
40 have been designed with a hooked edge that prevents or reduces
the chance of the pawls or arms from disengaging or slipping off
the tooth during actuation.
[0074] The axle bearing 34 of the units display unit 33 is mounted
on the units display unit axle 18 of the chassis 2. The internal
profile of the units display unit 33, including axle bearing 34,
and the external profile of the units display unit axle 18 are
designed to engage closely to allow relative rotational movement
without wobble. This may be achieved by close circumferential
engagement of the internal profile of the units display unit 33 and
the external profile of the units display unit axle 18 over most of
the circumference corresponding to positions on the units display
unit axle 18 that are axially separated by some distance. This
distance is preferably greater than the thickness of the portion of
the units display unit 33 that bears indicia. The units display
unit axle 18 may be substantially cylindrical, or it may have
cylindrical sections of different diameter such that the proximal
section is the larger diameter section. The units display unit axle
18 may have a lead-in surface at the distal end to facilitate
placing of the units display unit 33. The units display unit 33 may
be prevented from axial translation by the units display unit stop
arm 32 protruding from the displacement plate 19.
[0075] An advantage of embodiments of the invention is achieved
because the drive means is adapted to engage the first display unit
on a curved path, the drive means being driven by a force starting
from outside the circumference of the first display unit. This
improves the stability of indexing when the units display unit 33
is mounted on the chassis 2 because it allows freer movement of the
drive pawl 6 past the display unit 33 without advancing an
additional, unwanted count. In the rest position, the drive pawl 6
sits above the first of the units display unit 33 indexing teeth 38
and the non-return arm 8 is engaged with the first of the units
display unit non-return teeth 40 (that prevent reverse rotation of
the units display unit 33).
[0076] Preferably the drive pawl 6 and non-return arm 8 act at
opposite sides of the units display unit axle 18, which allows less
stringent tolerance requirements for the dimensions of the axle 18
and axle bearing 34.
[0077] The units display unit 33 has on its face a units display
surface 36 with a plurality (ten numerals 0 to 9 in the illustrated
embodiment) of units indicia 37 to indicate the remaining
doses.
[0078] Between the units display unit indexing teeth 38 and units
display unit non-return teeth 40, there is a tens display unit
drive tooth 39 that, when the tens display unit is fitted to the
dose indicator, drives the indexing teeth of the tens display unit
once per cycle of the units display unit 33. In the embodiment of
FIG. 4 with ten drive teeth 38, the tens display unit would be
driven once every 10 cycles.
[0079] The units display unit 33 has been designed such that it can
be injection moulded without the requirement for a side action in
the moulding tool. This is advantageous, as it will reduce the
capital cost of tooling and reduce the risk of flash on
components.
[0080] FIG. 6 shows the tens display unit 42 which is of generally
annular form with 21 tens display unit indexing teeth 46 evenly
distributed around the circumference of the tens display unit 42.
The tens display unit drive tooth 39 has been given a rounded
leading edge to ensure that the point contact with the tens display
unit indexing teeth 46 has a high incident angle for as long as
possible. An angled edge has been provided on the trailing side of
the drive tooth 39 and the leading edges of the tens display unit
indexing teeth 46 to reduce the chances of a double tens count
occurring whilst maximizing the overlap between these teeth.
[0081] A zero stop 44 (in the form of a boss) protrudes from the
tens display unit 42 and interacts with the zero stop arm 16 of the
chassis 2 at the end of the life of the dose indicator i.e. when
the maximum number of counts has been made, e.g. when the displayed
indication reaches zero.
[0082] The tens display unit 42 has a tens display unit display
surface 48 which rotates as the tens display unit 42 is indexed.
FIG. 6 shows the tens display unit display surface 48 as having a
series of indentations 49. In a more preferred embodiment, these
would be replaced by tens indicia (not shown), e.g. in the form of
a sequence of numerals "20", "19", . . . down to either "00" or "0"
or a blank. These numerals, and those of the units indicia 37, may
advantageously be produced by hot foil printing, moulding,
embossing, laser marking, or other suitable means. A viewing cut
out 30 in the chassis frame 4 of the chassis 2 allows the
juxtaposition of the indicia on the tens display unit 42 and those
from the units display unit 33 to be seen, such that together they
display the count or indication of doses (e.g. of remaining
doses).
[0083] The tens display unit 42 has a rim on its outermost edge
which acts as a bearing surface whilst ensuring that the printed
display cannot rub against the inside wall of the chassis 2. The
tens display unit 42 is located centrally in the chassis 2 by the
bearing rim on the outermost surface. It is located axially by a
series of clip and location features 10, 24 on the chassis 2.
[0084] The tens display unit non-return arm 28 interacts with the
tens display unit indexing teeth 46 and prevents rotation in the
reverse direction and restricts rotation in the drive direction
except when receiving an impulse from the tens display unit drive
tooth 39 on the units display unit 33.
[0085] The tens display unit 42 has been designed such that it can
be injection moulded without the requirement for a side action in
the moulding tool. This is advantageous, as it will reduce the
capital cost of tooling and reduce the risk of flash on components.
To assemble the dose counter 1, the units display unit 33 is
mounted on the units display unit axle 18 on the chassis frame 4.
The tens display unit 42 is then hooked under the tens display unit
locating ledge 24 and pushed past the two tens display unit clips
10. Once assembled, the dose counter 1 can then be inserted into an
actuator as an assembled unit.
[0086] FIG. 7 shows the dose counter part way through actuation.
During operation of the dose counter 1 upon actuation of the pMDI
valve, the displacement plate 19 bends at its hinges and follows a
generally arcuate displacement path. The drive pawl 6 also follows
an arcuate path. The drive pawl 6 is angled into the units display
unit indexing teeth 38, to further help secure engagement and to
reduce the chance of the drive pawl 6 unintentionally disengaging
from the units display unit indexing teeth 38. The engagement of
the drive pawl 6 with the units display unit indexing teeth 38
advances the display of the units display unit 33 by one count, and
the drive pawl 6 then continues its travel as far as it continues
to be driven by the user, up to the limit of travel of the pMDI
valve. The rotation of the units display unit 33 by one count
results in the non-return arm 8 being forced to flex and to ride
over the next one of the units display unit non-return teeth
40.
[0087] On the return stroke, the spring force of the spring arms 12
causes the drive pawl 6 to return to its original, rest position.
The non-return arm 8 engages with the next of the units display
unit non-return teeth 40, thus preventing reverse rotation of the
units display unit 33. Since the units display unit 33 is unable to
rotate, the drive pawl 6 is forced to ride over the next of the
units display unit indexing teeth 38 and return to its rest
position.
[0088] On a tens count (e.g. for a displayed count changing from
"190" to "189"), as the counter is indexed the rotation of the
units display unit 33 causes the tens display unit drive tooth 39
(on the units display unit 33) to engage with tens display unit
indexing teeth 46. The tens unit display unit non-return arm 28
resiliently distorts under the driving force, and once the stroke
is completed it detains the tens display unit 42 on the next of the
tens display unit indexing teeth 46.
[0089] Once the dose counter 1 reaches a display of zero, the zero
stop arm 16 on the chassis frame 4 and zero stop 44 on the tens
display unit 42 come into engagement and prevent further rotation
of the tens display unit 42. Interference between the last of the
tens display unit indexing teeth 46 and the tens display unit drive
tooth 39 on the units display unit 33 in turn prevents the units
display unit 33 from rotating further. Due to the resilient
flexibility in the chassis 2, spring arms 12 and drive pawl 6, the
inhaler can still be actuated once the stop-at-zero features become
engaged.
[0090] The indexing of the units display unit 33 and tens display
unit 42 occurs on the down-stroke of the actuation. This is
advantageous, as work on the dose counter 1 is being carried out by
the user (rather than, for example, by spring return force, which
would be limited). This leads to a more reliable device, as the
function of the spring arms 12 is only to reset the counter.
[0091] Due to the properties required for the spring arms and
ratchets, the chassis 2 is preferably made from polyoxymethylene
(also known as POM or acetal) or material with similar properties
(high stiffness, low friction and good dimensional stability).
Preferably the acetal is an acetal homopolymer. POM and materials
with similar properties tend to be opaque hence the need for a cut
out portion in the chassis and corresponding window in the actuator
body so that the indicia are visible.
[0092] The chassis 2 has been designed such that it can be
injection moulded without the requirement for a side action in the
moulding tool. This is advantageous, as it reduces the capital cost
of tooling and reduces the risk of flash on components.
[0093] FIG. 8 shows an alternative embodiment of a dose indicator
101 part way through actuation, comprising a chassis 102 with a
chassis frame 104 of generally annular form. The embodiment of FIG.
8 also has spring arms 112, a drive pawl 106 driving the indexing
teeth 138 of a units display unit 133, and a tens display unit 142
with tens display unit indexing teeth 146. The units display unit
has non-return teeth 140 that interact with the non-return arm 108
of the chassis 102 and, in this embodiment, a boss protrusion 143
on the boss 141 which on pressing down of the displacement plate
119 during actuation interacts with a forked deadstop 145 moulded
integrally with the displacement plate 119. This is advantageous
because is prevents the springs 112 and hinges being overstressed
during use, e.g. if the user presses with a force significantly in
excess of that needed to operate the dose indicator and to actuate
the valve.
[0094] As shown in FIG. 9, a third embodiment of a dose counter 201
according to the invention comprises a chassis 202 with a chassis
frame 204 of generally annular form. The chassis 202 incorporates a
number of features including springs, hinges and indexing features
that are used to actuate and reset the device. These features are
formed integrally with the chassis 202.
[0095] The dose counter 201 is somewhat similar to that shown in
FIG. 1, so only those features that differ will be described.
[0096] A displacement plate 219 is attached to the chassis 202 by
two hinges 220. The hinges 220 have bridge-shaped features to
direct most of the flexing to the thinner regions at the apex of
each bridge. The displacement plate 219 is also attached to the
chassis 202 by two spring arms 212, joined to the chassis 202 on
the opposite side to the hinges, and joined to the displacement
plate 219 by lateral extensions to the plate that are just to the
side of the stem post aperture 214 further from the hinges 220. The
spring arms 212 are designed to flex transversely to the axis of
the hinges, to provide additional return force for the displacement
plate 219 without any twisting of the spring arms. The hinges 220
are slightly further forward towards the units display unit 233
than are the hinges 20 of the embodiment in FIG. 1: this reduces
the distance of pMDI metering valve stem movement needed to cause
the dose counter to index. The displacement plate 219 has an
integral drive pawl 206, and is formed integrally with the spring
arms 212, hinges 220 and chassis 202. The displacement plate 219
does not have a units display unit stop arm, however, as this
feature 216 is provided instead on the tens display unit locating
ledge 224 of the chassis frame 204 (FIG. 11). The design provides
for the boss 241 to sit close to the actuator valve stem post of
the inhaler (not shown) when the dose counter is assembled into the
inhaler.
[0097] The units display unit 233 has a single set of gear teeth
238, corresponding to the indexing teeth 38 (see e.g. FIG. 1), that
also serve to engage a non-return arm 208 and so also act as
non-return teeth. When it is assembled into the chassis 202, the
units display unit 233 is retained on the chassis 202 because the
non-return arm 208 goes around the units display unit 233 and
engages the gear teeth 238.
[0098] During a return stroke, the drive pawl 206 must ride over a
tooth while the non-return arm 208 prevents the units display unit
233 from rotating backwards. The gear teeth 238 arc shaped such
that the long side of each tooth has a convex surface. The
component of force from the flexing drive pawl 206 that acts to
resist return of the displacement plate 219 is thereby reduced
later in the travel when the force applied by the spring arms 212
is reducing: return is less hindered by the drive pawl 206 having
to ride over a gear tooth with a convex surface.
[0099] The chassis 202 has downwardly directed legs 247 on either
side of the chassis and integrally formed with it, for precisely
positioning the dose counter in an inhaler actuator. The legs have
vertical grooves 248, which may engage internal vertical ribs of
the actuator to prevent any rotational movement of the dose
counter. The legs have feet 249 that are turned inwards to form
clips that locate in recesses located on the floor of a pMDI
actuator (not shown). Alternatively, the feet may locate on top of
ribs or other features in the actuator. The dose counter may
advantageously be located in the actuator by an interference
(friction) fit; alternatively clipping features may be
provided.
[0100] FIG. 10 shows a view in which the tens display unit drive
tooth 239 is about to engage a tens display unit indexing tooth
246b. The angled forward surface of each indexing tooth 246
combined with the relative planes in which the tens display unit
242 and units display unit 233 lie, ensure that the tens display
unit drive tooth 239 has clearance whilst having an adequate
vertical rear surface of the indexing tooth 246b to engage with to
rotate the tens display unit 242 to just past the desired amount.
Thence the tens display unit non-return arm 228 (not visible in
FIG. 10: see FIG. 9) will adjust the position of the tens display
unit, e.g. by slight back rotation, to align indicia thereon with
the viewing cut out 230 (see FIG. 2 for the corresponding part
30).
[0101] FIG. 11 shows zero stop arm 216 of the chassis 202 engaging
the zero stop 244 of the tens display unit 242. Once this point of
travel is reached, a further count of nine can be made on the units
display unit 233. After that, the tens display unit drive tooth 239
is stopped by the last indexing tooth 246, and the units display
unit 233 can no longer rotate. Downward movement of the
displacement plate 219 causes the drive pawl 206 to engage a tooth
238 that does not move, due to the stopping of the tens display
unit. Under this load, the drive pawl 206 deflects allowing
additional doses to be taken upon this and subsequent actuations
with minimal additional resistance to actuation. The drive pawl 206
is angled (relative to a vertical line) both away from the axis of
the hinges 220 and also inwardly towards the axis of the tens
display unit 242.
[0102] FIGS. 12a and 12b respectively show the embodiment of FIGS.
1 to 7 and an alternative embodiment, similar except in the detail
of the mounting means for mounting the units display unit. FIG. 12a
shows the units display unit 33, the units display unit axle 18 and
the axis of the axle X. The external surface of the axle is shown
in close engagement with the internal surface 35 of the units
display unit axle bearing 34, for a substantial part of the length
of the axle bearing. FIG. 2 shows that one side of the axle 18 has
a flat, which avoids the possibility of compressing air between the
axle and bearing during assembly and thereby making them
susceptible to separation. In FIG. 12b, the units display unit axle
18 has two circumferential engagement surfaces 51, 53 for
engagement, at least for most of the circumference, with an
internal double-cylindrical profile 55 of the units display unit
33. The two surfaces are separated along the axis of the axle 18 to
provide stability against wobble. A slight lead-in (e.g. a
radiussed or chamfered edge) is provided on the distal end (the end
that is engaged deepest into the units display unit) of the axle 18
to help with assembly.
[0103] FIG. 13 shows a pressurised metered dose inhaler (pMDI) 260
comprising a canister 263 including a metered dose-dispensing valve
265 mounted via a ferrule 264 on to the neck of a vial 272
component of the canister 263 with an elastomeric gasket 266 to
create a seal. The inhaler 260 comprises an actuator 261 including
a mouthpiece 268 (in an alternative form, suitable for nasal drug
delivery, the actuator may comprise a nosepiece rather than a
mouthpiece). The canister 263 is placed within the actuator 261 by
inserting the valve stem 269 of the valve 265, which protrudes
outside the ferrule 264, into a stem socket 273 of a stem post 262
of the actuator 261. The valve stem 269 has a dispensing passage
that allows for passage of substance from a metering chamber of the
valve 265 out through the valve stem 269 and actuator mouthpiece
268 (or nosepiece) to the user. To actuate (fire) the valve 265 to
deliver a dose of medicament formulation, the valve stem 269 is
pushed inwardly relative to the aerosol container from its resting
position, allowing formulation to pass from the canister through
the valve 265 and through the actuator nozzle 270 and then out to
the patient. The actuator 261 has a dose counter 201 mounted around
the stem post 262. The dose counter 201 has a units display unit
233, a tens display unit 242 a chassis frame 204 and a displacement
plate 219. During actuation, the canister 263 is pressed down by
the user. As the canister 263 is pressed into the actuator 261, the
ferrule face 271 surrounding the valve stem 269 contacts indexing
knuckles 226 and displaces the displacement plate 219. The result
is that the drive pawl (206; not visible in FIG. 13) indexes the
units display unit 233 in the manner described above.
* * * * *