The present invention relates to an apparatus and method for dispensing small quantities of particles.
WOA-01/33176 discloses so apparatus and method for dispensing small quantities of particles, in particular smaB amounts of medicament especially in a powder form. The apparatus uses dispense head comprising a funnel shaped hopper with a plurality of holes in a membrane at the base of the hopper, forming a sieve-like element, through which powder present in the hopper may rail. A preferred method is to tap the hopper horizontally to cause such a movement, thereby controllably dispensing powder through the membrane. The tapping is achieved by an electro-mechanical actuator which delivers impact energy to the hopper, which in turn causes a small number of particles to fill through the sieve-like element and onto a weighing measuring balance. The actuator is a horizontally oriented solenoid which taps the side of the hopper via a rod which supports the hopper at one end and has the solenoid mounted at the other end. A tapping action can also be done with a vertical component to the action of the actuator or the resultant movement of the hopper.
Figure 1 shows schematically the dispensing bead of a precision powder metering system as described in WO-A-Ol/33176.
Reierring to Figure 1, the device consists of a powder dispense lead comprising a hopper 1 for a powder material, for example a medicament used for administration to the lungs of a patient via a powder inhale* or a medicament to be filled into a gelatin capsule which can, be eaten by a patient Hie hopper 1 is of generally nrasto-comcal form with the larger end ~2 open ami uppeimostr-^Ebe-snialler end 3 is closed by a plate 4 in which a plurality of holes 5 are formed, thereby fbrming a sieve. When a powder 7 is placed in me hopper 1,. some powder 7 may initially fell through the holes 5 but thereafter, in general, the powder flow .stops as the powder 7 jams in the boles 5. The flow of powder 7 through Hie holes 5 can be made controllable and reproducible by the choice of appropriate dimensions for the holes to march the properties of the powder. Typically, the holes he in the range of from 100 microns to 2000 microns.

In older to use the :tr>p.iniiiis for precision dispensing, a receptacle 8 for the powder 7 is placed under the plaic 4 ;md the hopper 1 is tapped on the sidewall 9 thereof at a location 6. The tap may be in ;i form mat results from the impact of a mass travelling at a controlled velocity, fur example from the end of an electromechanical tapping actuator, such as a solenoid. The resulting motion of the hopper 1 and powder 7 causes the powder 7 to flow through the hole* 5 in (he plate 4 for a small period of time following the impact, SffiTwIaWfnTpWdcr fl»w sioTSsr Thwffii«m*e~anioant of-powder-7ns-controBably dispensed into the receptacle 8 as a result of each tap.
hi order to accurately dispense a desired total amount of the powder 7, a plurality of taps are used to £11 each rccq>lucle 8 and the total weight of powder 7 dispensed into the receptacle 8 is measured in real time so that as soon as the required amount has been dispensed, the tapping can he stopped. The rate of tapping is controlled by a control computer. If desired, a mechanical action on the dispense head other man tapping may be employed controllably 10 dispense the powder.
It is disclosed that the hopper is usually damped to a rod which carries the electro
mechanical tapping actuator so as to ensure that the hopper cannot move relative to the
rod However, another arrangement is disclosed in which the hopper is not clamped and
merely sits in an aperture in the rod so as to be able to be perturbed vertically and/oi
rotetionafly. It is staled lhat it is thought mat (be actuator provides a horizontal force
which is converted in part to a vertical force at the hopper side walls, possibly due to the
tapered nature of these side walls, and that the rotations are thought to he due tc
asymmetries in the components, for example when the plane of the aperture in Che rod in
which the hopper sits is not precisely horizontal. It is disclosed that the vertical motion
"serves to fluidise fflg powder particles, making (hem easier to dispense, and that the
rotational motion can help the particles from bejng compressed or otherwise stuck
together. .
The known dispense head described hereinabove relies for its effectiveness on its ability to dispense roughly consistent amounts of powder with each successive mechanical action or tap. This occurs because a roughly similar amount of drug powder is released through the

holes on each occasion, as the bridge of powder over any given hole is broken. In a typical application the powder may consist of particles which are 20 to 100 microns diameter, and the holes may be 300 or 400 microns diameter.
This known sysiem wore? very weu wiin me nmjuniy vi mtuxtuus. nuwever it has some shortcomings when loaded with materials which have a tendency to agglomerate. Sometimes drug materials can be ground or milled down to very small particle size, to help with drag dissolution and absorption within the patient, or for other purposes. When the small particles arc of the order of a few microns in diameter, the powder is typically described in the art as being 'micronised'. These materials frequently have a tendency to form large loose agglomerates when handled. These agglomerates take the form of larger assemblies of particles formed from loosely grouped individual particles, rather like snowballs made from powdered snow. These larger particles may be many different sizes - commonly ranging from tens of microns in diameter up to 2 or 3 millimetres in diameter,, 6t even larger.
It will be appreciated that wim a powder which has a tendency to agglomerate, me holes may become occluded by agglomerated assemblies of particles whose diameters are greater man me hole diameters. Although some smaller particles may be released, the amount can be very small, and thus .the process of dispensing may take considerably longer as a consequence and in some circumstances render me process of dispensing by the dispense head unachievable.
Attempts to remedy this by employing a disoense head which has larger holes are only of limited success, because the agglomerates are not of consistent size. The result of this is that the amount of drug released from the dispense head for any given tap or mechanical action becomes very variable.—If the agglomerates bemme larger, then flic flow ia restricted again. If the agglomerates are locally smaller, then too large amounts of powder can be released, leading to potential over dispensing above the target value, and the process is more difficult to control.
The disclosure in WO-A-01/33176 concerning me provision of an undamped hopper which is free to some extent to move vertically and/or rotationally in an aperture does not

provide controlled and repeatedly achievable effects on the powder during dispensing so as to be able to ensure avoidance of agglomeration of the powder particles.
The present invention at least partially aims to overcome these problems ol tne Known apparatus and method for dispensing small quantities of particles using a dispense head.
Accordingly, the present invention provides an apparatus for dispensing small quantities of particles, the apparatus comprising a hopper provided with a sieve at a bottom portion thereof, the hopper defining a powder-containing zone 'above the sieve which in use contains powder to be dispensed therefrom through the sieve, a support for the hopper, the support holding a portion of the hopper so that the hopper .can in use be held above a container into which the dispensed powder is to be received, at least one actuator for delivering impact energy to the hopper for causing powder to be dispensed through the sieve when the hopper receives the impact energy, and an element, which is adapted to permit controlled vertical movement of the hopper relative to the support
In one preferred, aspect, the element comprises a clamp for clamping the hopper to the support, we clamp being configured to permit the hopper to move vertically in the olamped configuration over a particular distance.
X
The apparatus may further comprise a biasing device between the hopper and the support for biasing die hopper to a first position of die clamped configuration, the hopper being tnovable towards a second position of the clamped configuration against the bias of the biasing device.
Preferably, the biasing device comprises a compression spring.
The compression spring may be disposed between two pans 01 we ciamp ana urges me hopper downwardly.
In aootner emDOOuneni, me eiemeni comprises a stop memocr, spaced wove a HUIUOT for the hopper, to define a height by which the bolder cart move vertically

The apparatus may further comprise a height adjustment mechanism for adjusting the height of the stop member.
Jh another preferred aspect, the support comprises an annular pardon having am aperture within which the hopper is received, the upper surface of the annular portion has a stepped ratchet configuration adapted additionally to create controlled rotational movement of the hopper, and a holder for the hopper rests on the stepped ratchet configuration.
Preferably, the stepped ratchet configuration comprises a succession of abutting inclined step portions extending peripherally around the upper surface of the annular portion.
Preferably, the step portions are separated by radially directed edges.
Preferably, the holder is provided with a plurality of downwardly depending members Wrudh rest on the ratchet surface.
The present invention also provides a method of dispensing small quantities of particles, the method comprising the steps of: disposing in a hopper provided with a sieve at a bottom portion thereof a powder to be dispensed therefrom through the sieve; supporting the hopper by holding a portion of me hopper -with a support so that the hopper is held above a container into which the dispensed powder is to be received, and providing an element which is adapted to permit controlled vertical movement of the hopper relative to the support; and delivering impact energy to the hopper by at least one actuator thereby to
t * . *
cause powder .to be dispensed through Ihe sieve when the hopper receives the impact energy and to permit controlled vertical movement of the hopper relative to me support
a one preferred aspect, the elememl coiupusea a dtuup for clamping the hopper to the support, the clamp being configured to permit the hopper to move vertically in the clamped configuration over a particular distance.
Preferably, a biasing device is disposed between the hopper and the support for biasing the hopper to a first position of the clamped configuration, the hopper being movable towards a second position of the clamped configuration against the bias of the biasing device.

Preferably, the biasing oevice comprises a compression spring. The compression spring may urge the hopper downwardly.
In another embodiment, the element comprises a stop member, spaced aoove a noiacr 101
the hopper, to define a height by which the holder can move vertically. .
. Preferably, the height of the stop member is adjustable.
In another preferred aspect, the element is adapted additionally to create controlled rotational movement of the hopper relative to the support.
Preferably, the support comprises an annular portion having an aperture within which th< hopper is received, the upper surface of the annular portion, has a stepped ratchet configuration adapted to create rotational movement of the hopper, and a holder for the hopper rests on the stepped ratchet configuration.
Preferably, {he stepped ratchet configuration comprises a succession of abutting inclined step portions extending peripherally around the upper surface of the annular portion.
Preferably, die step portions ate separated by radially directed edges.
Preferably, the holder is provided with a plurality of downwardly depending memoers which rest on the ratchet surface.
Tretera^Iy;ioBBi5Batmt)veffleiot of the lioppej causes a change in the at least one of the-angle and direction of tilt of the hopper.
This invention accordingly provides the advantage that the powder in the hopper is subjected to a deagglomeration action as a result of controlled vertical, and optionally additional rotational movement, and possibly rating, of the hopper during powder dispensing, which tends to form a more homogeneous distribution of particle sizes, as a

result of the deagglomeration action tending to reduce particle agglomeration in the hopper by physical breaking op of any agglomerates and/or by preventing any further agglomerates from being formed. This in turn tends to permit more accurate dispensing of the target weights of the powder, with in particular less incidence of over dispensing above the target dispensed weight, and also tends to provide more even dispensing tunes
***••*•» . •' ' • ^ w •
for successive doses of the same target weight
The present invention is predicated on the discovery by the inventors that the
*
agglomeration problem can reliably and repeatably be reduced or substantially eliminated by mechanically treating the powder immediately prior to dispensing while the powder is ih the hopper, by controllably moving the hopper vertically and optionally additionally rotationally, and/or by tilting the hopper, in the aperture.
Embodiments of me present invention will now be described by way of example only with reference to the accompanying drawings, in wbich:-
Figure 1 is a schematic section, from one side, through a hopper of a known powder dispensing apparatus for dispensing powder into a receptacle;
Figure 2 is a schematic section, from one side, through a hopper, and a tapping device of a powder dispensing apparatus in accordance with the present invention for dispensing powder into a receptacle;
Figure 3 is an enlarged schematic section, from one side, of the topper of Figure 2 showing the clamping arrangement for the hopper in accordance with a first embodiment of the present invention;
Figure 4 is an enlarged schematic section, from one side, of the hopper of Figure 2 showing the clamping arrangement for the hopper in accordance with a second embodiment of the present invention; the clamp constituting a stop member to define a limit of vertical movement of the hopper;

Figure 5 is a schematic plan view of an am for supporting a hopper which is incorporated in a powder dispensing apparatus in accordance with a third embodiment of the present invention;
Figure 6 is a schematic side view of the arm of Figure 5;
Figure 7 is a schematic side view of the arm of Figure 5 when supporting a hopper which is incorporated in the powder dispensing apparatus in accordance with the third embodiment of the present invention;
Figure 8 is a schematic plan view of the arm of Figure 7 showing the Contact points between the supporting pawls on the ring for the hopper and the plurality of inclined races on the upper surface of the supporting ring of the arm; and
Figure 9 is a schematic section, from one side through a hopper and a tapping device in accordance with a further embodiment of the present invention for dispensing powder-into a receptacle.
Figure 2 shows a hopper and a tapping device of a powder dispensing apparatus in accordance with the present invention for dispensing powder into a receptacle. In this embodiment, a frusta-conical hopper 20 has a sieve (not shownX in the form of a horizontally oriented plate with a plurality of sieving holes therethrough, at its smaller lower end 22 and a larger upper end 23 for receiving bulk powder, such as medicament, to be dispensed through the sieve. The hopper 20 is supported by a cantilever arm 25, which is attached to or bears against a sidewaU 26 of the hopper 20. Within the cantilever arm 25 is provided a longitudinally directed cavity 27, and in the cavity 27 is disposeda loogitudnraHy oriented solenoid coil 28 of a- solenoid 30, comprising an electro-mechanical actuator. Use coil 28 is rigidly attached to the cantilever arm 25. An armature 31 of the solenoid 30 comprises a longitudinally extended body having a projecting portion 33, extending within the coil 28. A helical spring 34 is provided, to bias the armature 31 so as "to be partly located in the coil 28. The projecting portion 33 has an end wall 35 spaced from a respective end face 37 of the cavity 27 in the rest position as a result of the bias from the spring 34.

When a current pulse is passed through the coil 28, the armature 31 is accelerated towards the end face 37 of the cavity 27 and the end wall 35 impacts it. The impact momentum is transferred by the cantilever arm 25 to the hopper 20 and the bulk powder therein and causes a discrete amount of the powder to fell into a receptacle (not shown) located, in use, beneath the sieve of the hopper 20. Thereafter, when the current pulse is terminated the spring 34 urges the armature 31back to the rest position.
With mis arrangement it is possible to tap the hopper 20 along file cantilever arm 25. Accordingly, powder dispensing occurs by successive tapping steps corresponding to successive powder dispense actions.
The use of a solenoid 30 to generate the impact on the hopper 20 and the bulk powder therein allows the magnitude of the impact to be altered by controlling the voltage driving the coil 28 of the solenoid 30. The same effect can be achieved by changing the pulse width, i.e. the period of time during which the cofl 28 is switched on.
The problem of agglomeration of the bulk powder in the hopper 20 above the sieve 21 is overcome in accordance with the invention by the provision of a support for the hopper 20 which is permits controlled vertical, and optionally additional rotational, movement of the hopper 20, and optionally also causes the axis of the hopper 20 to tilt about an angle relative to the vertical. These structures can assist in either preventing the formation of agglomerates and/or breaking op any agglomerates which have formed. A number of different embodiments of the hopper support structures are described below.
Referring to Figure 3, there is shown a first embodiment of a hopper support structure, The hopper support structure 40 comprises a clamp member 42 having an end part 44 which engages a peripheral ring 46 affixed to the hopper 20 around the outer wall 48 of the hopper 20. The end part 44 bears downwardly on an upper surface 52 of the ring 46. The end part 44 may extend wholly or partly around the periphery of the hopper 20. The clamp member 42 also has a body part 54 having a central hole 56 extending downwardly therethrough, an upper surface 58 and a lower surface 60. An opposite end part 45 of the

clamp member 42 bears against the upper surface 62 of the cantilever arm 25 at a fulcrum part 50. A threaded bolt 64 extends downwardly through the hole 56 and the end thereof is received in a threaded bore 66 in the cantilever arm 25. A helical compression spring 68 is disposed about the bolt 64 between the head 70 of the bolt 64 and the upper surface 58 of the clamp member 42.. The helical compression spring 68 thereby applies a controlled downwardly directed bias onto the hopper 20 via the engagement of the end part 44 and the ring 46. The threaded bolt 64 may be threadably adjusted so as to alter the degree of the downwardly directed bias on the hopper 20. The holt 64 may be provided with incremental axial positions whereby the vertical position of the holt 64, and thereby the degree of bias and the total distance that (he hopper 20 is able to move vertically, can be altered incrementally, for example over a total distance of 2 mm in 0.25mm increments. This provides an indexed control over the bias on the hopper 20, and also on the maximum distance that the hopper 20 is able to be moved vertically id (he cantilever arm 25.
keferfing to Figure 4, there is shown a second embodiment of the present invention, incorporating a hopper support structure, designated generally as 80, for mounting the hopper 20 on the cantilever arm 25. The hopper support structure 80 comprises a clamp member 82 having an end part 84 which can bear against a peripheral ring 86 affixed to . the hopper 20 around the outer wall 88 of the hopper 20. The end part 84 extends around the periphery of the ring 86 and can bear downwardly on an upper surface 92 of the ring 86. The clamp member 82 also has a body part 94 having a central hole 96 extending downwardly therethrough, an upper surface 98 and a lower surface 100. A second opposite end 102 of the clamp member 82 has a fulcrum part 104 extending downwardly therefrom which bears against the upper surface 106 of the cantilever arm 25. A threaded bolt 108 extends downwardly through the hole 96 and the end thereof is received in a threaded bore 110 in the cantilever arm 25. The head 114 of me bolt 110 engages the upper surface 98 of (he clamp member 82 and a helical compression spring H2-it— disposed about the bolt 110 between the upper surface 106 of the cantilever arm 25 and the lower, surface 98 of the clamp member 82. The helical compression spring 112 thereby applies a controlled upwardly directed bias onto the clamp member 82. The threaded bolt 110 may be threadably adjusted so as to alter the angle of inclination, about the fulcrum part 104, of the clamp member 82 and thereby the vertical position of the end part 84 of the clamp member 82. The bolt 110 maybe provided with incremental axial

positions whereby tine vertical position of the boh 110, and thereby the vertical position o the end part 84 of the clamp member 82, can be altered incrementally. As shown in FJgun 4, the hopper is disposed, in use, in an undamped position where the end part 84 is remote from and above the peripheral ring 86, thereby acting as a stop member defining a heigh range over which the hopper can jump -when impacted. The vertical component of an} movement of the hopper relative to the support is thereby limited in a controller manner.
For each of the embodiments of Figure 3 and Figure 4, when the hopper 20 is subjected tc the tapping action as shown by the arrows in Figures 3 and 4, the tapping action causes the hopper 20 to be nioved not only horizontally, bat also vertically, as a result of the hoppei 20 receiving impact energy from the actuator. For Hie embodiment of Figure 3, tiu amount of upward vertical displacement caused by the impact is controlled by the amouni of the biasing force applied by the helical spring. For bom embodiments the maximum vertical displacement is controlled by the longitudinal position of the bolt, which in ton controls the vertical position of the end part of the clamping member.
Referring to Figures 5 to 8, there is shown a further embodiment of the present invention In this embodiment, as shown in particular in Figures S and 6, the cantilever ann 125 ij provided at its free end 126 with ah annular portion 127 haying a central aperture 121 within which the hopper 129 is movably received. The upper surface 130 of the anaulai portion 127 lias a succession of abutting inclined step portions 131 extending peripherally thejearoimd. The step portions 131 are separated by radially directed edges 132. The opiper surface 132 of each step portion 131 is inclined to the horizontal and afl the step portions 131 are inclined in the same direction. Accordingly, the upper surface 130 of the annular portion 127 is formed as a circumferential ratchet surface 130. The step height at each ratchet step edge may be from 0.2 to 1 mm.
Turning to Figures 7 and 8, the hopper 129 is provided on its inclined outer surface 133 with an annular ring member 134 which is attached thereto, at a vertical height above the centre of gravity of me hopper 125 and ring member 134, and extends circumferentially outwardly from the hopper 129. The ring member 134 is provided with a plurality of downwardly depending pawl members 13S. Each pawl member 13S has a lower end 136 which rests on the ratchet surface 130 of the annular portion 127. The number of and

angular relationship between the pawl members 135 are selected, in conjunction with the dimensions and angular relationship of the step portions 131, so that in any rotational position of the hopper 129, the pawl members 135 engage with different vertical features as they rest on respective step portions 131 of the ratchet surface 130. This causes the hopper 129 to rotate about a vertical axis in response to horizontal movement of the cantilever arm 25 when the cantilever aim 25 is impacted., hi the illustrated embodiment, three pawl members 135 are provided, at mutual angles of 120 degrees to each other, and the angular arrangement of the step portions 131 is selected so that each pawl member 135 rests at a respective step height on its respective step portion 131. The number of pawl members 135 and the orientation of the pawl members 135 and the step portions 131 can be varied within the scope of the invention. A clamp member 136, helical compression spring 138 and bolt 140 are provided, having a similar structure as in the embodiment of
F
Figure3. An end port 142 of the clamp member 136 bears downwardly against the upper
surface 144 of the ring member 134 under the bias of the spring 138, me bias being
adjustable by the bolt 140. This structure permits the ring member 134, and thereby the
hoppet 129, to move vertically, as described in greater detail below, in a controlled
manner against the bias of (he spring 138, which acts to define the limit of the vertical
component of any movement of the hopper. .
When the cantilever arm 125 receives impact energy fiom the actuator, not only does this impart a horizontal impact on the hopper 129, but also this causes the hopper 129 to jump vertically. When the hopper 129 receives impact energy in a horizontal direction from the actuator towards me hopper 129, the junction between the hopper 129/pawl members 135 remote from the actuator leads to act as. a fulcrum which is vertically above the centre of gravity of the filled hopper. This causes the hopper to be rotated upwardly about that fulcrum, thereby moving the opposite side of the hopper vertically upwardly. This vertical mo^Tcnds to W associated with at least a small rotational movement about a vertical axis as well When the hopper 129 rotates, the pawl members 135 tend progressively to be moved, in. an angularly indexed manner, ctrcumferentially around the ratchet surface 130. The provision of the ratchet surface 130 not only permanently tilts the hopper 129, but also causes rotation of the hopper 129, and consequential variation in both the angle and direction of tilt, even for only email amounts of rotational movement, particularly when a pawl member 135 suddenly drops down the height of a step portion 131 of the ratchet

surface 130. The angle of maximum rotation per indexed rotational motion is controlled by the angular extent of each step portion 131. The maximum vertical movement per indexed rotational (nation is controlled by the vertical height of each steo Dortion edee 132.
Figure 9 shows ;i nnxiitieatuwi or the powder dispensing apparatus ot figure z. In this modification, the dcciro-nu'chaaical actuator 150 is oriented vertically rather man horizontally as in Figure 2. The electromechanical actuator ISO thereby provides impact energy in a vertical dirvci ion io> ihe cantilever arm 25, and thereby to (be hopper 20.
ID each of the embodiments of the invention, tbe controlled vertical, andoptionally additional rotational motion of the hopper, coupled optionally with tilting of the hopper, assists in deagglomcraiing the powder particles in the hopper, which in turn enhances even and accurate powder dispensing from the hopper.

CLAIMS
1. An apparatus for dispensing small quantities of particles, the apparatus comprising
a hopper provided with a sieve at a bottom portion thereof, the hopper defining a powder-
containing zone above the sieve which in use contains powder to be dispensed therefrom
through the sieve, a support for fte hopper, the support holding a portion of the hopper so
that the hopper can in use be held above a container into which the dispensed powder is to
be received, at least one actuator for delivering impact energy to the hopper for causing
.powder to be dispensed through the sieve when the hopper receives die impact energy, and
an element which is adapted to permit controlled vertical movement of the hopper relative
to the support.
2. An apparatus according to asm i wnerem me element comprises a ciamp ior
clamping fhe hopper to the support, the clamp being configured to permit the. hoppor to
move vertically in the clamped configuration over a particular distance,
3. An apparatus according to claim 2 further comprising a biasing device between the
hopper and the support for biasing the hopper to a first position of the clamped
configuration, the hopper being movable towards a second position of the clamped
configuration against the bias of (he biasing device.
4. An apparatus according to claim 3 wherein fhe biasing device comprises a
compression spring.
5. An apparatus according to claim 4 wherein the compression spring is disposed
between two parts of the clamp and urges the hopper downwardly.
6. An apparatus according to claim 1 wherein the element comprises a stop memoer,
spaced above a holder for the hopper, to define a height by which ibe holder can move
vertically.
7. An apparatus according to claim 6 farther comprising a height adjustment
mechanism for adjusting the height of the stop pparatus according to any one of claims 1 to 5 wherein the support comprises an annular portion having an aperture wiiirin which the hopper is received, the upper surface of the annular portion has a stepped ratchet configuration adapted additionally to permit rotational movement of the hopper,, and a holder for (he hopper rests on the stepped ratchet configuration.
P. An apparatus according to claim 8 wherein the stepped ratchet configuration comprises a succession of abutting inclined step portions extending peripherally around foe upper surface of the annular portion.
10. An apparatus according to claim 9 wherein the step portions are separated by
radially directed edges.
11. An apparatus according to any one of claims 8 to 10 wherein the holder is provided
ritfa a plurality of downwardly depending members which rest on the ratchet surface.
12. A method of dispensing small quantities of particles, die method comprising the
steps of: disposing in a hopper provided with a sieve at a bottom portion thereof a powder
o be dispensed therefrom through the sieve; supporting the hopper by holding a portion of
he hopper with a support so that the hopper is held above a container into which the.
dispensed powder is to be received, providing an element which is adapted to permit
controlled vertical movement of the hopper relative to the support; and delivering impact
energy to the hopper by at least one actuator thereby to cause powder to be dispensed
through the sieve when the hopper receives the impact energy and to pennit controlled
vertical movement of Che hopper relative to the support.
13. A method according to claim 12 wherein the element comprises a clamp for
clamping the hopper to the support, the clamp being configured to permit the hopper to
move vertically in the clamped configuration over a particular distance.
14. A method according to claim 13 wherein a biasing device is disposed between the
hopper and the support for biasing the hopper to a first position of the clamped
configuration, the hopper being movable towards a second position of the clamped configuration against the bias of the biasing device.
15. A metfiod according to claim 14 wnerem the biasing device comprises a
compression spring.
16. A method according to claim IS wherein the compression spring urges the hopper
downwardly.
17. A method according to claim 12 wherein the element comprises a stop member;
spaced above a holder for the hopper, to define a height by which the holder can move
vertically.
18. A method according to claim 17 wherein the height of the stop member is
adjustable.
19. A method according to claim 12 wherein the element is adapted to permit
controlled rotational movement of the hopper relative to the support
20. A method according to claim 19 wherein the support comprises an annular portion
having an aperture within which the hopper is received, the upper surface of the annular
portioa has a stepped ratchet configuration adapted to permit rotational movement of the
hopper, and a bolder for the hopper rests on the stepped ratchet configuration.
21. A method according to claim 20 wherein the stepped ratchet configuration
comprises a succession of abutting inclined step portions extending peripherally aronnd
the upper surface of the annular portion.
'11. A metnod according to claim 21 wnerem me step portions are separatee oy raoiauy directed edges
23. A method according to any one of claims 18 to 22 wnerem the holder is provided with a plurality of downwardly depending members which rest on the ratchet surface.
24. A method according to any one of claons 19 to 25 wherein rotational au>vc*u«" «.•.
the hopper causes a change in the at least one of the angle and direction of tilt of the
hopper.
25. An apparatus for dispensing small quantities of particles substantially as
hereinbefore described with reference to Figure 3, Figure 4, Figures 5 to 8 or Figure 9.
26. A method for dispensing small quantities of particles substantially as hereinbefore
described with reference to Figure 3, Figure 4, Figures 5 to 8 01 Figure 9.