Powder dispenser

Abstract

A powder dispenser 204 including a funnel 236 for dispensing a dose of powder through an outlet 243, a vibrator 244 to assist with the flow of powder towards the outlet, a plug 238, and an actuator 24

Description

BACKGROUND OF THE INVENTION The present invention relates to a powder dispenser and an appliance for dispensing and weighing powder. When using a powder in a domestic setting, it is often desirable to have a dispenser which dispenses a dose of the powder, to avoid the user having to touch the powder itself. This may be useful for dispensing powders that may stain, e.g. dye, or powders which are easily contaminated e.g. foodstuff powder. In the preparation of a mixture from a powder, e.g. a foodstuff powder in order to quickly prepare a safe and enjoyable food or beverage, it can be necessary to use a specific dose of powder in relation to the rest of the ingredients. In some cases, for example when preparing infant formula from milk powder, it is important that this dose is as precise as possible. It is therefore desirable to have a powder dispenser or an appliance which dispenses a precise dose of a powder. Additionally, many powders are moisture-sensitive, e.g. foodstuff powders, and will spoil if exposed to humid air for an extended period of time, for example in a kitchen. This is particularly concerning in the preparation of infant formula, which may expire or not dissolve properly if exposed to a humid environment. It is therefore desirable to have a powder dispenser which can protect powder from ambient humidity, to avoid wastage or use of spoiled powder. It is an object of the invention to provide a powder dispenser which is able to dispense a precise dose of powder, and protect unused powder from the environment when the dispenser is not in use. 05 06 25 SUMMARY OF THE INVENTION From a first aspect, the invention provides a powder dispenser comprising: a funnel for dispensing a dose of powder through an outlet, wherein the funnel 5 comprises an upper portion and a lower portion, and a constriction arranged along an axis between the upper portion and lower portion; a vibrator arranged to vibrate at least the upper portion of the funnel to assist with the flow of powder towards the constriction; a plug arranged in the constriction wherein, in a natural state of the funnel, the 10 constriction makes contact with the plug so as to seal off the upper portion; and an actuator arranged to move one of the lower portion and upper portion relative to the other of the lower portion and upper portion along the axis, and thereby open the constriction relative to the plug so as to allow a flow of powder from the upper portion to the lower portion and towards the outlet. 15 Thus it will be seen that, in accordance with embodiments of the first aspect of the invention, the actuator can be operated to open the constriction so that the upper portion is connected to the lower portion to allow a flow of powder from the upper portion to the lower portion through the constriction. The skilled person will appreciate 20 that the “natural state” of the funnel refers to a configuration that is naturally and stably adopted when there are no external forces acting on the funnel. In this natural state, i.e. when the actuator is not acting on the funnel, the constriction has a configuration (e.g. width dimension) that causes it to make contact with the plug, e.g. sealing around the plug. This means that powder contained in the upper portion of the funnel can be 25 sealed off from the outlet of the funnel when the powder dispenser is not in use, to prevent air and moisture from entering the upper portion and potentially spoiling any undispensed powder remaining therein. When the funnel is moved by the actuator, the constriction is no longer in contact with the plug, such that the constriction is opened and the plug may not block the constriction and powder may flow through the outlet. It 30 is the relative movement between the upper and lower portions which acts to open the constriction, thereby determining whether powder can pass through the constriction. It will be understood that the constriction is a region of the funnel which is narrower compared to each of the upper portion and the lower portion. The constriction may 35 have a dimension (e.g. a width dimension), in a direction generally perpendicular to 05 06 25 the axis of the funnel as defined between the upper portion and lower portion, which is less than the corresponding dimension of the upper portion and the lower portion. For example, the actuator may open the constriction by moving the constriction down relative to the plug, and / or by increasing the width of the constriction relative to the 5 plug. Furthermore, this (e.g. width) dimension of the constriction can change from a maximum value when the constriction is opened by the actuator, to a minimum value when the funnel is in its natural state. The corresponding dimension of the upper 10 portion and / or lower portion may not substantially change when the funnel is adjusted between its expanded and natural states. Preferably, the openness of the constriction is variable, e.g. the constriction has a variable width. In some embodiments, the upper portion may be frustoconical. In some embodiments, 15 the lower portion may be frustoconical. For example, the funnel may be hourglassshaped. When the funnel is in its natural state, the upper portion is sealed off at the constriction by the plug. This means that powder contained in the upper portion of the funnel is 20 unable to flow through the constriction to reach the lower portion and hence cannot be dispensed through the outlet. The natural state of the funnel may seal off the upper portion by narrowing the diameter of the opening of the constriction, that is, the constriction may narrow as the funnel contracts towards its natural state. The sealing effect may arise from the constriction sealing around a face of the plug, to seal closed 25 the upper portion. The sealing effect may also, or alternatively, arise from the constriction being made sufficiently narrow such that powder bridging prevents the flow of powder from the upper portion to the lower portion. The plug may be arranged such that the constriction can allow a flow of powder past 30 the plug, from the upper portion to the lower portion and hence to the outlet of the funnel, when the constriction is opened. For example, the constriction may seal azimuthally around the plug when the funnel is in the natural state. Preferably, the plug is fixed in position and the actuator is arranged to move the lower 35 portion (and / or the upper portion) relative to the plug, such that when the funnel is in 05 06 25 the natural (i.e. contracted) position, the plug is positioned to block the constriction and hence seal off the upper portion of the funnel and close the powder dispenser. When the constriction is opened by the actuator, in some examples the funnel may be expanded by the actuator such that the constriction of the funnel is no longer 5 obstructed by the plug and hence the upper portion of the funnel is completely unsealed. At a position between the natural state of the funnel and a fully opened state of the constriction, the flow of powder may be partially obstructed by the plug in some examples. The rate of flow of powder through the constriction may be varied (e.g. continuously) between zero (when the constriction is blocked by the plug in the natural 10 state), and a maximum when the flow of powder through the constriction is minimally obstructed by the plug. In some embodiments, the actuator is arranged to move the lower portion of the funnel relative to the upper portion of the funnel. For example, the actuator may be attached 15 to the lower portion of the funnel, such that the actuator may move up to close the constriction, and down to open the constriction. In at least some embodiments, adjusting the funnel between the natural state and an expanded state acts to vary the degree of opening of the constriction and the degree of contact, e.g. sealing, of the constriction with the plug, and hence vary the flow rate of powder through the 20 constriction. The actuator can therefore adjust the flow rate of powder through the outlet by adjusting the state of the funnel between its natural state (e.g. zero flow rate) and its fully expanded state (e.g. maximum flow rate). In some embodiments, the upper portion, lower portion, and constriction comprise a 25 plurality of concentric rings. The funnel therefore has a circular geometry in crosssection. In some embodiments, the upper portion and the lower portion may each comprise a concentric ring of substantially the same diameter. In some embodiments, the lower portion may comprise a concentric ring having a smaller diameter than the concentric ring of the upper portion, i.e. the lower portion is generally narrower than 30 the upper portion. The constriction comprises a concentric ring having a smaller dimeter than the concentric rings of the upper and lower portions. In some embodiments, the power dispenser is for a powder that is a foodstuff or beverage powder. It will be seen by those skilled in the art that the invention is 35 preferably used for dispensing powders in a domestic setting (e.g. dispensing foodstuff 05 06 25 and beverage powders). The powder dispenser may therefore be a domestic powder dispenser. The actuator may be arranged to selectively seal and unseal the upper portion of the 5 funnel by operating to either close (e.g. completely close) the constriction or to open the constriction. In a set of embodiments, the funnel may comprise at least one fold between the upper portion and the lower portion, such that moving the funnel to expand the fold acts to open the constriction relative to the plug. For example, the funnel may concertina, e.g. about the fold, in order to move between the natural state 10 and an expanded state. The actuator may be arranged to move the funnel from a natural state that is a folded state to another natural state that is an unfolded state. In some examples, the funnel may be bistable. The actuator may be arranged to move the funnel bistably between its folded and unfolded states. In such embodiments, the constriction may comprise a fold extending azimuthally around the axis of the funnel 15 defined between the upper portion and lower portion. In a set of embodiments, the actuator is arranged to open the constriction to a varying degree in order to vary a rate of flow of powder through the constriction, by stretching the funnel to a varying degree between its natural state and one or more expanded 20 states. When the powder dispenser is in use (e.g. dispensing powder), the actuator may operate to unseal the upper portion of the funnel, at varying degrees between sealed, partially open and completely open, by expanding the funnel from its natural state, a partially expanded state, and a fully expanded state. 25 In any embodiment described herein, the flow of powder through the constriction from the upper portion to the lower portion may be assisted by gravity. The actuator may be operated manually, for example comprising a mechanism attached to the funnel that can be manually moved to seal and unseal the upper 30 portion of the funnel, by expanding the funnel and hence opening the constriction. In at least some embodiments, the actuator operates automatically to selectively seal and unseal the upper portion of the funnel. In a set of embodiments, the powder dispenser may further comprise a processor that is arranged to automatically control the actuator. The actuator may be operated automatically based on the processor 35 receiving an input signal, for example an input signal from a user or a feedback signal 05 06 25 from another part of the appliance (e.g. a feedback signal from a weighing system as described below). Alternatively, or in addition, the actuator may be operated automatically by the processor based on a dispensing time or dispensing program (e.g. which has been pre-programmed and / or selected by a user). 5 A benefit of automatically controlling the actuator is that the upper portion of the funnel is sure to be sealed following a dispensing cycle without requiring manual intervention. This may be further assisted by the natural state of the funnel ensuring that the constriction is in contact with the plug, hence sealing the upper portion of the funnel, 10 when the actuator is not acting on the funnel. Furthermore, as described further below, automatic control of the actuator may also be used to controllably vary a rate of flow of powder through the outlet, e.g. in response to a feedback signal. In some embodiments, the upper portion of the funnel comprises a larger volume than 15 the lower portion of the funnel. This may be useful where the upper portion of the funnel is arranged to store a large volume of powder, e.g. act as a powder reservoir. In some embodiments, the funnel is mounted in contact with the vibrator. In some embodiments, the funnel is brought into contact with the vibrator when the constriction 20 is open (i.e. when the upper portion of the funnel is unsealed). Preferably, the vibrator is fixed in position, however in some embodiments the vibrator may be adjustable relative to the position of the funnel. In some embodiments, there may be a plurality of vibrators arranged to be in contact with the funnel (e.g. at least) when the constriction is open. The vibrators may be mounted to a ring, which may additionally support the 25 upper portion of the funnel. For example, the ring may be compliant, e.g. made of an elastomeric material, which may isolate the vibrators from the rest of the powder dispenser such that the vibrators may oscillate with a full range of motion. Furthermore, the ring may deform when the vibrators are in contact with the funnel. 30 In some embodiments, the funnel is made of an elastomeric material (e.g. natural or synthetic elastomer, e.g. a silicone-based material). For example, the funnel may be brought into contact with the vibrator when the constriction is only partially open, e.g. funnel is only partially expanded, to assist with the flow of powder towards the constriction. When the constriction is fully opened, e.g. the funnel is fully expanded, 35 the funnel may elastically deform to accommodate both the expansion of the funnel 05 06 25 and contact with the vibrator, e.g. when the constriction is open and the upper portion of the funnel is unsealed. Furthermore, the elastomeric material may improve sealing between the funnel and the plug at the constriction. 5 In some embodiments, the actuator is arranged to elastically deform the funnel to open the constriction relative to the plug. The natural state of the funnel may be a state where there is no elastic deformation of the funnel, e.g. the constriction seals around the plug when there is no elastic deformation. Therefore, when the constriction is opened by the actuator, the funnel may elastically deform to accommodate expansion 10 of the funnel, to open the constriction and unseal the upper portion of the funnel, e.g. by widening the constriction such that it no longer seals around the plug and / or by moving the constriction away from the plug. When the force from the actuator is removed from the funnel, the funnel may elastically return to the natural state, e.g. where the upper portion of the funnel is sealed. 15 In a set of embodiments, e.g. where the funnel is elastomeric, the funnel elastically deforms in response to the vibrations, which may further assist the flow of powder towards and / or through the constriction. In this set of embodiments, the funnel may deform when brought into contact with the vibrator, for optimal transmission of 20 vibrations from the vibrator to the powder. In some embodiments, where the constriction comprises a circular opening, the plug comprises a cylinder. In some embodiments, the diameter of the widest portion of the plug is substantially the same as the width of the constriction when the funnel is in the 25 natural state, thereby forming a seal between the constriction and the plug such that no powder is able to escape from the upper portion to the lower portion of the funnel. In some embodiments, where the funnel is made from an elastomeric material, the inner width of the constriction may be less than the diameter of the widest portion of the plug. The plug may push on the inner surface of the constriction, flexing the 30 elastomeric material and creating an air-tight seal. In some embodiments, the plug is tapered to assist with sealing. For example, the plug may have a maximum circumference at its upper end and a minimum circumference at its lower (i.e. sealing) end. The plug may be tapered in order to create an air-tight seal 35 in the event that the inner circumference of the constriction of the funnel is larger than 05 06 25 the outer circumference of the minimum circumference of the plug. In some embodiments, the plug may comprise a domed and / or spherical portion, e.g. at the end of the plug. This may assist with the sealing of the constriction in the natural state of the funnel. 5 In some embodiments, the upper portion of the funnel may be stiffened relative to the lower portion of the funnel. For example, the upper portion may comprise one or a plurality of rigid supporting elements, e.g. spokes, to help prevent sagging of the upper portion of the funnel. For example, the rigid supporting elements may be embedded 10 within the upper portion of the funnel, e.g. sandwiched between or overmoulded by layers of elastomeric material making up the upper portion of the funnel. In addition, or alternatively, the upper portion of the funnel may be made of a stiffer material than the lower portion of the funnel. 15 Stiffening the upper portion of the funnel relative to the lower portion of the funnel may ease the movement of the lower portion of the funnel relative to the upper portion, such that it is easier to collapse the funnel. Furthermore, stiffening the upper portion of the funnel may also help to prevent deformation of the funnel, for example sagging, under the weight of undispensed powder. This may ease the flow of powder towards 20 the constriction and hence the outlet. Preferably, the actuator is arranged to move the lower portion of the funnel down relative to the upper portion of the funnel, which is substantially supported or fixed in place. In some embodiments, a rigid element, e.g. a rigid actuating ring, may be 25 comprised in or attached to the lower portion of the funnel. For example, a lower portion of the funnel may include a rigid actuating ring at the outlet of the funnel, e.g. where the rigid actuating ring circles the entire outlet of the funnel. This may ease the opening of the constriction by the actuator. For example, in embodiments where the funnel is made of an elastomeric material, it may be easier for the actuator to come 30 into contact with (e.g. grasp onto) and translate the rigid element in order to expand the funnel, without pinching the funnel. In a set of embodiments, the actuator pulls down on the rigid element to open the constriction. The actuator may comprise a rotating mechanism, including a set of 35 retractable jaws, wherein rotation of the rotating mechanism brings one or more of the 05 06 25 set of retractable jaws into contact with the rigid element. The rotating mechanism may be arranged to move the jaws radially inward before the jaws are moved linearly downward to come into contact with the top of the rigid element. The rotating mechanism may be arranged to move the rigid element downwards by the jaws 5 pushing down on the rigid element, thus moving the lower portion of the funnel downwards. This may increase the width of the constriction and unseal the upper portion of the funnel. Using a rotating mechanism can help to keep the powder dispenser compact. 10 For example, the rotating mechanism may rotate to come into contact with the rigid element when the powder dispenser is in use, and then move the jaws downwards to unseal the upper portion. The actuator in the form of a rotating mechanism may convert a rotational motion to linear motion of the rigid element and lower portion of the funnel, e.g. using a ramp. The rotating mechanism may alternatively comprise a 15 clamp that attaches to the rigid element, however preferably the jaws of the rotating mechanism push down on the rigid element to move the lower portion of the funnel downwards whilst avoiding pinching or rotating the funnel. The jaws may protract in order to be in contact with the funnel to move the constriction from the natural state to an open state. The jaws may retract in order for the funnel to move back to the natural 20 state, e.g. by elastically returning to the natural state, e.g. the jaws may retract such that the actuator no longer acts on the funnel. The rotating mechanism may comprise at least one jaw. Preferably, the rotating mechanism comprises three jaws, such that there are three points of contact with the 25 funnel such that the rigid element has substantially the same force acting on all sides, such that the constriction opens symmetrically. The rotating mechanism may be azimuthally symmetric, such that the funnel may be positioned within the rotating mechanism at any angle and the rotating mechanism 30 may still be able to act on the rigid ring. This may be useful if the powder dispenser is being reassembled e.g. after being cleaned and / or refilled. In a set of embodiments, the powder dispenser of the first aspect of the invention is connected to a weighing system within a powder dispensing appliance. The weighing 35 system includes a load cell arranged to weigh a dose of powder dispensed from the 05 06 25 funnel, and a processor arranged to be programmed with a target weight. The processor can be arranged to compare the weight of the dose of dispensed powder with the target weight. In such embodiments, a comparison result from the processor can be used to provide a feedback signal to the powder dispenser. The feedback 5 signal to the powder dispenser may simply control the actuator to seal the outlet or upper portion of the funnel when it is determined that the target weight has been reached. This corresponds to a zero flow rate. In other embodiments, the feedback signal to the powder dispenser may adjust the rate of flow of powder from the powder dispenser to a suitable non-zero value depending on the comparison result, for 10 example by varying the degree to which the outlet or constriction is open. The outlet or constriction may be opened more if the target weight is not being reached quickly enough, or the outlet or constriction may be opened less to slow the flow as the target weight is approached. This may allow for the weight of the full dose of dispensed powder to be as close to the target weight as possible, such that the dose of powder 15 dispensed is precise (e.g. within 1 g of the target weight). In a set of embodiments, the actuator is controlled in response to the feedback signal. For example, the actuator can adjust the flow rate of the powder being dispensed through the outlet or constriction, e.g. by adjusting the vertical position of the funnel 20 and / or the plug, or by collapsing and expanding the funnel as previously described. The actuator may be controlled by its own processor or directly controlled by the processor carrying out the weight comparison. There is disclosed further herein an appliance for dispensing and weighing a powder, 25 comprising a powder dispenser and a weighing system; wherein the powder dispenser is arranged to dispense a dose of a powder through an outlet at an adjustable flow rate; wherein the weighing system comprises: a load cell arranged to weigh a dose of powder that has been dispensed 30 through the outlet; and a processor arranged to be programmed with a target weight; wherein the processor is arranged to compare the weight of the dispensed powder with the target weight; and wherein a comparison result from the processor is used to send a feedback 35 signal to the powder dispenser for adjusting the flow rate through the outlet. 05 06 25 There is disclosed further herein an appliance for dispensing and weighing a powder, comprising a powder dispenser and a weighing system; wherein the powder dispenser is arranged to dispense a dose of a powder through a constriction of a funnel at an 5 adjustable flow rate depending on an openness of the constriction; wherein the weighing system comprises: a load cell arranged to weigh a dose of powder that has been dispensed through the outlet; and a processor arranged to be programmed with a target weight; 10 wherein the processor is arranged to compare the weight of the dispensed powder with the target weight; and wherein a comparison result from the processor is used to send a feedback signal to the powder dispenser for adjusting the flow rate by varying the openness of the constriction. 15 As mentioned above, the comparison result can indicate how quickly the weight of the dispensed powder is approaching the target weight. If the dispensed weight is far below the target weight then the feedback signal can be used to increase the flow rate through the outlet. If the comparison result indicates that there may be a blockage 20 preventing powder from being dispensed (e.g. due to no or little weight increase over a period of time), then the feedback signal may be used to adjust the flow rate by closing and re-opening the outlet or constriction. Once the dispensed weight reaches the target weight, the feedback signal can be used to seal the outlet or upper portion of the funnel as soon as the desired dose has been dispensed. 25 In a set of embodiments, the powder dispenser is arranged to reduce the flow rate of powder through the outlet in response to the feedback signal as the weight of the dispensed powder approaches the target weight. For example, a / the actuator may respond to the feedback signal (directly or via a processor) to move the funnel to a 30 different vertical position, or to collapse the funnel, in order to reduce the flow rate as the weight of the dispensed powder approaches the target weight. In a set of embodiments, the powder dispenser further comprises a vibrator arranged to vibrate the funnel to assist with the flow of powder towards the outlet (e.g. as 35 described above). The processor may control the vibrator depending on the 05 06 25 comparison result. For example, if the processor registers that the weight of dispensed powder is far from the target weight, it may increase the current supplied to the vibrator in order to increase agitation of the powder. In another example, the processor may register that the actuator has moved the funnel to a position out of contact with the 5 vibrator, and may turn off the vibrator as it is no longer in contact with the outer surface of the funnel. In some embodiments, in addition or alternatively, the powder dispenser is arranged to bring the outer surface of the funnel into contact with the vibrator (or vice versa) in response to the feedback signal. 10 The powder dispenser in this dispensing and weighing appliance may include any of the features already described in relation to the first aspect of the invention. In an example, the powder dispenser comprises a funnel for dispensing a dose of a powder through the outlet, and an actuator arranged to selectively seal and unseal the 15 outlet, wherein the outlet is defined by a boundary between an outer surface of the funnel and an inner surface of the funnel. In some further embodiments, the same actuator (or another actuator) may be arranged to dispense the dose of powder through the outlet at an adjustable flow rate in response to the feedback signal. For example, as is described in more detail above, a position of the funnel may be 20 adjusted by the actuator in order to vary the flow rate through the outlet in response to the feedback signal. In various embodiments, the actuator is arranged to open the outlet to a varying degree in order to vary a rate of flow of powder through the outlet. In some embodiments, the processor is arranged to automatically control the actuator 25 using the feedback signal. In some embodiments, the feedback signal is sent to a different processor arranged to control the actuator. In an example, the actuator is arranged to adjust a position of the funnel from a first (e.g. upper) position to a second (e.g. lower) position in response to the feedback 30 signal, wherein the outlet is sealed in one of the first position and second position, and wherein the outlet is unsealed in the other of the first position and second position. In some embodiments, the actuator is arranged to adjust a vertical position of the funnel in response to the feedback signal, in order to control a rate of flow of powder through the outlet. 05 06 25 In an example, the powder dispenser further comprises a plug, wherein the outlet is sealed by the plug when the funnel is in one of the first and second positions. In some embodiments, the powder dispenser comprises a funnel for dispensing a 5 dose of powder through an outlet, wherein the funnel comprises an upper portion and a lower portion, and a constriction arranged along an axis between the upper portion and lower portion; a vibrator arranged to vibrate at least the upper portion of the funnel to assist with the flow of powder towards the constriction; a plug arranged in the constriction, wherein, in a natural state of the funnel, the constriction makes contact 10 with the plug so as to seal off the upper portion; and an actuator arranged to move one of the lower portion and upper portion along the axis, relative to the other of the lower portion and upper portion, and thereby open the constriction relative to the plug so as to allow a flow of powder from the upper portion to the lower portion and towards the outlet. In some further embodiments, the same actuator (or another actuator) may be 15 arranged to dispense the dose of powder through the constriction at an adjustable flow rate in response to the feedback signal. For example, as is described in more detail above, the openness of the constriction of the funnel relative to the plug may be adjusted by the actuator, e.g. the funnel may be expanded by the actuator, in order to vary the flow rate through the constriction in response to the feedback signal. In 20 various embodiments, the actuator is arranged to open the constriction to a varying degree in order to vary a rate of flow of power through the outlet. In some embodiments, the actuator is arranged to move the funnel between a natural state and an expanded state in response to the feedback signal, wherein the upper 25 portion of the funnel is sealed by the plug being in contact with the constriction in the natural state, and wherein the upper portion is unsealed in the expanded state. In some embodiments, the actuator is arranged to adjust a state of the funnel between the natural state and an expanded state (e.g. by moving the lower portion up and down) in response to the feedback signal, in order to vary the opening of the 30 constriction and control a rate of flow of powder through the constriction. In some embodiments, the funnel is made of an elastomeric material (e.g. natural or synthetic elastomer, e.g. a silicone-based material). In a set of embodiments, the processor is arranged to calibrate the weighing system 35 using a tare weight of an empty container placed on the weighing system. This may 05 06 25 allow a user to place a container, e.g. a bottle, on the weighing system such that once the powder is dispensed, the mixture, e.g. infant formula, can be prepared directly, without impacting the precision of the dose of dispensed powder. 5 In a set of embodiments, the processor is able to register when an empty container is placed on the weighing system. The processor may identify when the load cell is at zero and the powder dispenser is off, and therefore that a container has been placed on the weighing system. 10 In any of the embodiments described herein, the powder dispenser or appliance may comprise a user interface. The user interface may include any suitable input element (e.g. a touchscreen, e.g. one or more buttons, dials, etc.) enabling a user to input or select a desired dose of powder to be dispensed. The actuator may be arranged to receive a signal from the user interface so that the outlet is unsealed at the start of a 15 dispensing cycle and sealed after the desired dose has been dispensed. A processor, e.g. as described above, may be used to automatically control the actuator during the dispensing cycle. Control of the actuator can be time-based, and / or based on an input from the user at the user interface, and / or based on a feedback signal from the weighing system (where one is included). 20 In another example, there is provided a computer-implemented method for dispensing and weighing a powder, wherein a processor is arranged to: receive a weight reading from a load cell that is arranged to weigh a dose of powder that is being dispensed from a powder dispenser; 25 compare the weight reading with a target weight; generate a feedback signal relating to a desired flow rate of the powder being dispensed from a powder dispenser depending on the comparison result. The target weight may be stored in a memory accessible by the processor. The target 30 weight may be pre-programmed, programmed by a user input, or programmed dependent on the container detected by the load cell. As described above, the processor may be arranged to send the feedback signal to the powder dispenser. The method may further comprise adjusting the flow rate 35 through an outlet of the powder dispenser, for example by controlling an actuator to 05 06 25 open the outlet to a varying degree based on the feedback signal. The method may comprise controlling a position of a dispensing funnel (e.g. relative to a fixed plug for the outlet) in response to the feedback signal. 5 The method may further comprise adjusting a funnel of the powder dispenser from the natural state to an expanded state, to open a constriction of the funnel to a varying degree based on the feedback signal. Another example relates to a computer program containing instructions that, when 10 implemented by a processor, carry out the method(s) described above. Features of any aspect or embodiment described herein may, wherever appropriate, be applied to any other aspect or embodiment described herein. Where reference is made to different embodiments or sets of embodiments, it should be understood that 15 these are not necessarily distinct but may overlap. BRIEF DESCRIPTION OF THE DRAWINGS Certain preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 20 Figure 1 shows schematically a perspective view of an appliance for dispensing and weighing powder; Figure 2 shows schematically a cross-section of the appliance shown in Figure 1; Figure 3a shows schematically an enlarged perspective cross-section of a 25 powder dispenser, shown for reference purposes only, for use in the appliance shown in Figure 1, when the powder dispenser is not in use; Figure 3b shows schematically a perspective cross-section of the powder dispenser shown in Figure 3a, when the powder dispenser is in use; Figure 4a shows schematically a cross-section of an alternative powder 30 dispenser according to an embodiment of the present invention for use in the appliance shown in Figure 1, when the powder dispenser is not in use; Figure 4b shows schematically a perspective cross-section of the alternative powder dispenser shown in Figure 4a; Figure 5a shows schematically a cross-section of the alternative powder 35 dispenser shown in Figure 4a, when the powder dispenser is in use; 05 06 25 Figure 5b shows schematically a perspective cross-section of the alternative powder dispenser shown in Figure 5a; Figure 6a shows schematically a view from below of the actuator of the alternative powder dispenser shown in Figure 4when the powder dispenser is not in 5 use; Figure 6b shows schematically a view from below of the actuator of the alternative powder dispenser shown in Figure 5 when the powder dispenser is not in use. Figure 7 shows schematically a system for operating an appliance for 10 dispensing and weighing powder. DETAILED DESCRIPTION Figure 1 shows an appliance 100 for dispensing powder. The appliance 100 comprises 15 a powder dispenser 104 and weighing system 106. The powder dispenser 104 is located at the upper end of the appliance housing 102, whilst the weighing system 106 is located at the lower end of the appliance housing 102, directly beneath the powder dispenser 104. Loose powder is placed into an upper vessel 105 of the powder dispenser 104, with 20 the inside of the vessel 105 accessed by opening the lid 108. A dose of the powder is then dispensed from the vessel 105 via an outlet (not shown) onto the weighing tray 110 of the weighing system 106. A container for receiving the powder (not shown), such as a baby bottle, may also be placed onto the weighing tray 110. 25 Figure 2 shows a cross-sectional view of the appliance 100 for dispensing powder shown in Figure 1. The powder to be dispensed is stored inside the vessel 105. A funnel 112 is fluidically connected to the vessel 105, such that powder entering the vessel 105 immediately enters the funnel 112, i.e. the vessel 105 and funnel 112 act together as a reservoir for the powder. 30 There is shown in Figures 2 and 3 an example, for illustrative and reference purposes only, of a funnel having an outlet which can be selectively sealed and unsealed. The funnel 112 has an outlet 116, which allows for a dose of powder to flow out of the powder dispenser 104 and fall onto the weighing tray 110. The outlet 116 is defined 05 06 25 by a boundary between an outer surface 113 of the funnel and an inner surface 111 of the funnel. Located inside the funnel 112 is a plug 114. The plug 114 is shown selectively sealing 5 the outlet 116 of the funnel 112. In the example shown in Figure 2, the funnel 112 is connected to an actuator in the form of a servo motor 118, where the servo motor 118 is located within the appliance housing 102. The servo motor 118 is arranged to raise and lower the funnel 112 relative to the plug 114. The plug 114 is fixedly attached to the vessel 104 and hence does not move relative to the appliance housing 102. 10 When the funnel 112 is in its upper position, as shown in Figure 2, the plug 114 blocks the outlet 116, such that the vessel 105 is sealed at its lower end and no powder is able to exit the powder dispenser 104, and no air or moisture is able to enter the powder dispenser through the outlet 116. This may help to prevent the powder 15 clumping together or otherwise deteriorating. When the funnel 112 is in its lower position (described below with reference to Figure 3b), the plug 114 does not block the outlet 116, and powder is able to flow out of the outlet 116 of the funnel 112. The funnel 112 may be moved to any position between its 20 upper and lower positions, in order to adjust the flow rate of the powder from the powder dispenser through the outlet 116. The dispensed powder falls from the outlet 116, and lands on the weighing tray 110 of the weighing system 106. The weighing system 106 comprises the weighing tray 110, 25 which sits on a load cell 126. The load cell 126 is connected to a processor 120. The processor 120 is also connected to the servo motor 118. The load cell 126 registers a weight of dispensed powder, e.g. received in a bottle or other container (not shown) placed on the weighing 30 tray, and sends this reading to the processor 120. The processor 120 is preprogrammed with a target weight (e.g. according to a dose amount input or selected by the user), which it compares with the weight of the dispensed powder. For example, the user may input the desired weight of powder or select a pre-set weight (e.g. in a baby milk powder dispenser, the user may input the age / size of the baby) via a user 35 interface 121. 05 06 25 A variety of different containers may be placed on top of the weighing tray 110. The processor 120 is able to calibrate the load cell 126 to absolute zero, by determining the tare weight of the container. For example, the user may be able to put the 5 processor 120 into a ‘calibration mode’, wherein the user places a desired powder weight onto the weighing tray 110, e.g. by measuring out a predetermined volume of powder on a spoon. The load cell 126 may record the desired powder weight, and the processor 120 may record this desired powder weight, such that this desired powder weight may be dispensed automatically in the future. 10 Based on the comparison result for the weight of dispensed powder, the processor 120 then sends a feedback signal to the servo motor 118, to either move the funnel up or down. For example, if the weight of the dispensed powder is close to the target weight, the processor 120 may send a feedback signal instructing the servo motor 118 15 to move the funnel up, in order to slow the flow of dispensed powder through the outlet 116, or to stop the powder being dispensed entirely. For example, the feedback signal may instruct the servo motor 118 to stop the powder being dispensed entirely when the weight of the dispensed powder is close to the target weight, and subsequently instruct the servo motor 118 to slightly unseal the outlet of the funnel such that a small 20 amount of powder is dispensed. This may allow for finer control over the powder dispensed close to the target weight. In another example, the feedback signal may instruct the servo motor 118 to gradually seal the outlet of the funnel to reduce the rate of powder dispensed, as the dispensed powder approaches the target weight. 25 In another example, if the weight of the dispensed powder is much lower than the target weight, the processor 120 may send a feedback signal instructing the servo motor 118 to move the funnel down, in order to increase the flow of the dispensed powder through the outlet 116. The servo motor 118, processor 120, and weighing system 106 are powered via a power supply 122 e.g. a battery and / or mains power 30 connection. Figure 3a shows an enlarged cross-sectional perspective view of the powder dispenser 104 shown in Figure 2, where the funnel 112 is in the upper (i.e. closed) position. It can be seen that the outlet 116, as defined by the boundary between the 05 06 25 outer surface 113 of the funnel and the inner surface 111 of the funnel, is sealed by the plug 114. The powder dispenser 104 also includes a vibrator 128 (e.g. a motor), which is 5 arranged to be in contact with the outer surface 113 of the funnel 112 when the funnel is in the lower position (i.e. dispensing powder), and not in contact with the outer surface 113 of the funnel 112 when the funnel is in the upper position (i.e. sealed). The vibrator 128 is arranged to vibrate the funnel, in order to assist the flow of powder towards the outlet 116 and help to break up any clumps in the powder. 10 The plug 114 is cylindrical, and passes continuously through the powder dispenser 105 and down the centreline of the funnel 112. The plug 114 is connected to the powder dispenser 105 at its upper (i.e. distal) end via spokes 115. The plug 114 is tapered towards its lower end 132. The outer circumference of the lower end 132 of 15 the plug 114 is slightly greater than the inner circumference of the outlet 116 of the funnel 112. This interference fit ensures that the plug 114 seals the outlet 116. The funnel 112 is made of an elastomeric material. When the funnel 112 is in the upper position, and the lower end 132 of the plug 114 fills the outlet 116 of the funnel 20 112, a seal 130 is formed between the lowest inner circumference of the funnel and the lower end 132 of the plug 114. The seal 130 is secured by the elastomeric funnel 112 elastically deforming to accommodate the plug 114, such that there is a compression between the plug 114 and the funnel 112. The seal 130 prevents powder leaking from the funnel 112, or unwanted moisture entering the funnel 112 through the 25 outlet 116 when the powder dispenser 104 is not in use. Figure 3b shows a perspective cross-sectional view of the powder dispenser 104 shown in Figure 3a, when the funnel 112 is in the lower (i.e. open) position. The funnel 112 has been moved down by the servo motor 118. In this position, the vibrator 128 is 30 in contact with the outer surface 113of the funnel 112. As the funnel 112 is made from an elastomeric material, it can be pressed against the vibrator 128 in this lower position, for optimal contact between the vibrator 128 and funnel 112, for transmission of vibrations through the funnel 112. This aids the flow of powder downwards through the funnel 112 and out through the outlet 116. 05 06 25 When the funnel 112 is in the lower (i.e. open) position shown in Figure 3b, the lower end 132 of the plug 114 is no longer sealing the outlet 116, such that powder may be dispensed under gravity. It is also possible to move the funnel 112 to a range of different vertical positions between the positions shown in Figures 3a and 3b, or to a 5 lower position than that shown in Figure 3b, to vary the flow rate of powder through the outlet 116. As the funnel 112 is lowered from the upper position, shown in Figure 3a, the flow rate of powder through the outlet 116 continually increases. This is due to the plug 114 protruding less into funnel 112. 10 In the illustrated embodiment of Figs. 1-3, loose powder is placed the upper vessel 105 of the powder dispenser 104 by opening the lid 108. Alternatively, the lid 108 is integrated with the plug 114, such that the plug 114 is removed to allow access to the inside of the vessel 105. The plug 114 may also be integrated with the vessel 105 and lid 108, with the funnel 112 instead being removable to allow loose powder to be 15 placed directly into the funnel 112.The plug 114 may also be removable from the vessel 105, e.g. for cleaning. Figures 4a and 4b show schematically a cross-sectional view of a second powder dispenser 204 according to an embodiment of the present invention, which is an 20 alternative powder dispenser to the dispenser 104 shown in Figures 1-3. The second powder dispenser 204 may be used with the appliance 100 instead of the powder dispenser 104 shown in Figures 1-3. The second powder dispenser 204 includes an expandable funnel 236, shown in 25 Figure 4a in its natural (i.e. closed) state, i.e. when the powder dispenser is not in use. The expandable funnel 236 is fluidically connected to the vessel (not shown), such that powder entering the vessel enters the expandable funnel 236, i.e. the vessel and the expandable funnel 236 act together as a reservoir for the powder. The expandable funnel 236 has an outlet 243, which allows for a dose of powder to flow out of the 30 powder dispenser 204 and fall onto the weighing tray of the appliance. The expandable funnel 236 is hourglass-shaped, including a wide upper portion 237 arranged to receive loose powder from the vessel (not shown), and a wide lower portion 241. In between the upper portion 237 and lower portion 241 of the funnel 236 35 is a constriction 240, which is the narrowest point of the expandable funnel 236. The 05 06 25 upper portion 237, lower portion 241, and constriction 240 are arranged such that they are concentric about an axis A, where the expandable funnel 236 is expanded parallel to the common axis A of the hourglass of the expandable funnel 236. 5 The upper portion 237 of the expandable funnel 236 has a larger volume than the lower portion 241, such that the upper portion 237 is able to act as a powder reservoir. Located inside the expandable funnel 236, there is a second plug 238. The second plug 238 is shown selectively sealing the constriction 240 of the expandable funnel 10 236. The second plug 238 is attached to the appliance housing (not shown). When the expandable funnel 236 is in its natural state, as shown in Figures 4a and 4b, the second plug 238 blocks the constriction 240, such that the upper portion 237 is sealed and no powder is able to exit, and no air or moisture is able to enter the upper 15 portion of the funnel 237, and hence the powder, through the outlet 243 or constriction 240. This may help to prevent the powder clumping together or otherwise deteriorating. The second plug 238 is cylindrical, and passes continuously through the second 20 powder dispenser 204 and down the centreline of the expandable funnel 236. The second plug 238 is connected to the second lid 245 of the second powder dispenser 204 at its upper (i.e. distal) end via spokes (not shown). The second plug 238 may be tapered, such that it is narrower at its lower end 239 than its upper end 235. 25 The second lid 245 is also arranged to attach to the upper portion 237 of the expandable funnel 236, such that the upper portion of the funnel is held open and may be more rigid than the lower portion of the funnel 241. The constriction 240 of the expandable funnel 236 has the same internal diameter as 30 the outer diameter of the lower end 239 of the second plug 238, such that when the funnel is in the natural state, the constriction 240 is arranged to form a seal around the second plug 238 and thus seals the upper portion 237. When the expandable funnel 236 is in its expanded position (described below with 35 reference to Figures 5a and 5b), the second plug 238 does not block the constriction 05 06 25 240, and powder is able to flow from the upper portion 237 to the lower portion 241 out of the constriction 240 and hence the outlet 243 of the expandable funnel 236. The expandable funnel 236 may be adjusted between its expanded and natural states to adjust the position of the constriction 240 relative to the second plug 238, in order to 5 adjust the flow rate of the powder from the second powder dispenser 204 through the outlet 243. The expandable funnel 236 is made of an elastomeric material, such that the expandable funnel 236 can be moved between a natural state shown in Figures 4a 10 and 4b, and an expanded position shown in Figures 5a and 5b by elastically deforming. This allows for the constriction 240 of the expandable funnel 236 to be moved relative to the second plug 238, to selectively seal and unseal the upper portion 237. The upper portion 237 of the funnel is stiffened by a rigid supporting element 233, which is embedded within the upper portion 237, to prevent the upper portion of the 15 funnel from sagging underneath the weight of the powder when in the expanded or natural states. The hourglass shape of the expandable funnel 236 has an axis A which is the same as the axis A of the second plug 238. For example, the upper portion 237, lower portion 20 241, and constriction may be viewed as a plurality of concentric rings. The second powder dispenser 204 also includes a vibrator 244 (e.g. a motor), which is arranged to be in contact with the outer surface of the expandable funnel 236. The vibrator 244 is arranged to vibrate the funnel 236, in order to assist the flow of powder 25 towards the outlet 243 and help to break up any clumps in the powder. The vibrator 244 is shown in contact with the upper portion 237 of the expandable funnel 236, however a vibrator may also be in contact with the lower portion 241 of the expandable funnel 236, for example the lower portion 241 may be brought into contact with a vibrator when in the expanded position shown in Figures 5a and 5b. As the 30 expandable funnel 236 is made from an elastomeric material, it may be pressed against the vibrator 244, for optimal contact between the vibrator 244 and expandable funnel 236, for transmission of vibrations through the expandable funnel 236. This aids the flow of powder downwards through the expandable funnel 236 and out through the outlet 243. 05 06 25 A rigid actuating ring 242 is attached to the lower portion 241 of the funnel, e.g. at the outlet 243. The rigid actuating ring 242 is connected to an actuator (shown with reference to Figure 6) is arranged to move the constriction 240 downwards (e.g. along the centreline of the expandable funnel 236), by moving the expandable funnel 236 5 from the natural state shown in Figures 4a and 4b, to the opened state shown in Figures 5a and 5b. A set of jaws 249 are connected to the actuator, shown in Figure 4b as retracted, i.e. not in contact with the rigid actuating ring 242. Figures 5a and 5b show schematically a cross-sectional view of the second powder 10 dispenser 204 shown in Figures 4a and 4b, when the expandable funnel 236 is in the open position i.e. when the powder dispenser is in use. The expandable funnel 236 has been moved down by the rigid actuating ring 242, as the jaws 249 of the actuator (shown with reference to Figure 6) are protracted and have moved radially inwards to be in contact with the rigid actuating ring 242, and the actuator has moved the jaws 15 249 and hence the rigid actuating ring 242 downwards. When the expandable funnel 236 is in the stretched state shown in Figures 5a and 5b, the lower end 239 of the second plug 238 is no longer obstructing the constriction 240, so that the upper portion 237 is no longer sealed and powder may be dispensed under 20 gravity. It is also possible to move the constriction 240 to a range of different vertical positions between the positions shown in Figures 4 and 5, or to a lower position than that shown in Figures 5a and 5b by expanding or collapsing the funnel, to vary the flow rate of powder through the constriction 240 and outlet 243. As the expandable funnel 236 is expanded from the natural state, shown in Figure 4, the flow rate of powder 25 through the outlet 243 continually increases. This is due to the second plug 238 protruding less into expandable funnel 236, e.g. protruding less into the constriction 240 which has moved downward. In the illustrated embodiment of Figs. 4-5, loose powder is placed in the upper portion 30 237 of the expandable funnel 236, e.g. by opening the second lid 245. Alternatively, the second lid 245 is integrated with the second plug 238, such that the second plug 238 is removed to allow access to the inside of the expandable funnel 236. The second plug 238 may also be integrated with the housing of the appliance (not shown) and lid 245, with the expandable funnel 236 instead being removable to allow loose 35 powder to be placed directly into the expandable funnel 236. 05 06 25 Figure 6a shows a cross-section of the second powder dispenser 204, viewed from beneath the second powder dispenser 204, when the powder dispenser 204 is not in use, i.e. the constriction 240 is blocked by the second plug 238. The rigid actuating 5 ring 242 is attached to the lower portion 241 of the funnel 236, and is arranged to not be in contact with a rotating mechanism 246 when the powder dispenser 204 is not in use. The rotating mechanism includes the set of jaws 249, shown in Figure 6a in the retracted position, i.e. they are not in contact with the rigid ring 242. The rotating mechanism is connected to an actuator 248, which may be connected to a motor (not 10 shown). The rotating mechanism 246 and actuator 248 are located below the expandable funnel 236. Figure 6b shows a cross-section of the second powder dispenser 204, viewed from beneath the second powder dispenser 204, when the second powder dispenser 204 is 15 in use, i.e. the constriction 240 is not blocked by the second plug 238. In order to expand the expandable funnel 236, the actuator 248 acts to move the rotating mechanism 246 such that the jaws 249 rotate and protract, such that they are above the rigid actuating ring 242. The actuator 248 then moves the rotating 20 mechanism 246 and the rigid actuating ring 242 downwards (i.e. parallel to the axis A of the expandable funnel 236), such that the jaws 249 push down on the rigid actuating ring 242 in order to stretch the expandable funnel 236, and move the constriction 240 downwards to unseal the outlet 243. The actuator 248 also acts to retract the jaws 249 of the rotating mechanism 246 , in order to release the 25 expandable funnel 236, and move the constriction 240 upwards to seal around the second plug 238 and thus seal the outlet 243, by allowing the expandable funnel to move elastically back to its natural state. The expandable funnel 236 is elastomeric and will return to its natural (i.e. collapsed) state when it is not being elastically deformed by the rotating mechanism 246. The actuator 248 rotates the rotating 30 mechanism 246 in order to release the jaws 249 from being in contact with the rigid actuating ring 242. The actuator converts the rotational motion of the rotating mechanism 246 to vertical linear motion of the rigid portion and lower portion of the funnel, using a ramp (not shown). The actuator 248 rotates anticlockwise to rotate the rotating mechanism 246, and hence protract the laws 249 to come into contact with 35 the rigid actuating ring 242 and move the funnel downwards. 05 06 25 Figure 7 shows schematically a control system 134 for operating the appliance 100 of Figures 1-6. The control system 134 includes the processor 120, servo motor 118, user interface 5 121 and vibrator 128, 244. The system 134 may also include the load cell 126. The processor 120 is configured to receive information from the user interface 121, where the user enters or selects a desired dose, e.g. based on volume or weight of power required, or a pre-set category (e.g. where the user enters the age / size of a 10 baby which has an associated volume or weight of baby milk powder). The processor 120 uses this information to set the target weight of powder to be dispensed. The processor 120 sends a signal based on the input from the user interface 121 to each of the vibrator 128, 244 and servo motor 118 / actuator 248, to actuate movement 15 of the funnel and / or plug, to begin dispensing the powder while the funnel is vibrating. The processor 120 may optionally be configured to receive the weight of dispensed powder from the load cell 126, and compare it to the pre-programmed target weight (e.g. as selected by the user). The processor 120 is then configured to control the 20 servo motor 118 / actuator 248 to adjust the position of the funnel 112, 234 to adjust the flow rate of the powder being dispensed through the outlet 116 or constriction 240, and / or to adjust the vibrations of the vibrator 128, 244. If the processor 120 is not configured to receive the weight of dispensed powder from 25 the load cell 126, the processor 120 may instead control the servo motor 118 / actuator 248 to move the funnel 112 down for a predetermined time expected to allow for flow of the desired dose through the outlet 116, or to expand the funnel 236 down for a predetermined time expect to allow for flow of the desired dose through the constriction 240. The processor 120 may additionally control the vibrator 128, 244 to 30 operate for a predetermined time expected to assist with flow of the desired dose. It will be appreciated by those skilled in the art that the invention has been illustrated by describing one or more specific embodiments thereof, but is not limited to these embodiments; many variations and modifications are possible, within the scope of the 35 accompanying claims. 05 06 25

Claims

1. A powder dispenser comprising:a funnel for dispensing a dose of powder through an outlet, wherein the funnel comprises an upper portion and a lower portion, and a constriction arranged along an5 axis between the upper portion and lower portion;a vibrator arranged to vibrate at least the upper portion of the funnel to assist with the flow of powder towards the constriction;a plug arranged in the constriction, wherein, in a natural state of the funnel, the constriction makes contact with the plug so as to seal off the upper portion; and10 an actuator arranged to move one of the lower portion and upper portion alongthe axis, relative to the other of the lower portion and upper portion, and thereby open the constriction relative to the plug so as to allow a flow of powder from the upper portion to the lower portion and towards the outlet.15 2. The powder dispenser of claim 1, wherein the actuator is arranged to open theconstriction to a varying degree in order to vary a rate of flow of powder through the outlet.

3. The powder dispenser of claim 1 or 2, further comprising a processor that is20 arranged to automatically control the actuator.

4. The powder dispenser of any preceding claim, wherein the upper portion and lower portion are frustoconical e.g. the funnel is hourglass-shaped.25 5. The powder dispenser of any preceding claim, wherein the upper portioncomprises a larger volume than the lower portion.

6. The powder dispenser of any preceding claim, wherein the plug comprises a 30 cylinder, and the constriction seals azimuthally around the plug.

7. The power dispenser of any preceding claim, wherein the plug is tapered.05 06 258. The powder dispenser of any preceding claim, wherein the plug has an outer diameter that is substantially the same as the width of the constriction in the natural state of the funnel.5 9. The powder dispenser of any preceding claim, wherein the funnel is broughtinto contact with the vibrator when the actuator opens the constriction.

10. The powder dispenser of any preceding claim, wherein the funnel is made of an elastomeric material.1011. The powder dispenser of any preceding claim, wherein the actuator is arranged to elastically deform the funnel so as to open the constriction relative to the plug.

12. The powder dispenser of any preceding claim, wherein the upper portion, lower 15 portion, and constriction comprise a plurality of concentric rings.

13. The powder dispenser of any preceding claim, wherein the funnel is removable.

14. The powder dispenser of any preceding claim, wherein the plug is removable.2015. The powder dispenser of any preceding claim, wherein the upper portion of the funnel is stiffened relative to the lower portion.

16. The powder dispenser of any preceding claim, further comprising a rigid25 element attached to the lower portion of the funnel.

17. The powder dispenser of claim 16, wherein the actuator pulls down on the rigid element to move the lower portion relative to the upper portion, and thereby open the constriction relative to the plug.30 18. An appliance for dispensing and weighing a powder, comprising a powderdispenser as claimed in any preceding claim and a weighing system;wherein the powder dispenser is arranged to dispense a dose of a powder through the outlet of the funnel at an adjustable flow rate depending on an openness of the constriction;35 wherein the weighing system comprises:a load cell arranged to weigh a dose of powder that has been dispensed through the outlet; anda processor arranged to be programmed with a target weight;wherein the processor is arranged to compare the weight of the dispensed5 powder with the target weight; andwherein a comparison result from the processor is used to send a feedback signal to the powder dispenser for adjusting the flow rate through the outlet, by varying the openness of the constriction.06 25

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