WO2022029425A1

WO2022029425A1 - Induction cooker

Info

Publication number: WO2022029425A1
Application number: PCT/GB2021/052009
Authority: WO
Inventors: Jack RAISON; Nicholas ORME
Original assignee: Njori Ltd
Priority date: 2020-08-04
Filing date: 2021-08-04
Publication date: 2022-02-10
Also published as: GB2597762A; GB202012088D0

Abstract

This disclosure provides an induction cooker, tool system and methods of use therefor which increase the reproducibility of cooking performance. An induction cooker comprises a heating component configured, in use, to cause heating of the foodstuff disposed in the container. A sensor is configured to measure a parameter of the foodstuff during heating, wherein the parameter is a function of the mass or the weight of the foodstuff disposed in the container. A controller is connected to the sensor and to the heating component. The controller is configured to monitor the parameter and to alter the heating caused by the heating component in response to a change in the value of the parameter. Additionally disclosed is an induction cooker for use with a container for a foodstuff, the induction cooker comprising a circuit configured, in use, to apply a signal to the container, to monitor a response to the signal and to derive a characteristic of the container based upon the response. The induction cooker further comprises an output means configured to output, to the user, an indication related to the derived characteristic. Also disclosed is a tool system for use with an induction cooker. The tool system comprises a first tool for sensing a property of the liquid or fluid foodstuff, a second tool for influencing a property of the liquid or fluid foodstuff and a separation means configured to determine the relative distance between the first tool and the second tool when each of the first tool and the second tool is disposed in the liquid or fluid foodstuff. At least one of the first tool and the second tool is configured to be removably attached to the separation means and/or to the other of the first tool and the second tool.

Description

INDUCTION COOKER

TECHNICAL FIELD

[1] The present invention lies generally in the technical field of cookers, and more specifically in the field of induction cookers that include features and accessories that increase the reproducibility of cooking performance.

BACKGROUND

[2] The cooking of foodstuffs is a daily activity worldwide. The preparation of high-quality cooked foodstuffs is a goal of many cooks when preparing and serving a meal. In both domestic and commercial settings, the quality of a cooked foodstuff is often seen as a reflection of the competence of the food preparer and over time a user preparing food may build a reputation for providing high-quality cooked foodstuffs for the consumption of themselves and others.

[3] One challenge that is often faced by a user who has previously been successful in preparing high-quality cooked foodstuffs lies in reproducing the same success on a later occasion. This challenge is all the more acute if the user’s reputation as a competent chef is on the line.

[4] In some circumstances, a reduction of a foodstuff, whereby vapours are driven off, forms a necessary step in the preparation of foodstuffs for consumption. Existing techniques for reducing foodstuffs typically require the presence of the user to continuously or intermittently monitor the progress of the reduction as it goes on whilst a cooker is used. This is because if the user leaves the preparation to be reduced without observing it, a risk exists of over-reducing the foodstuff by driving off too much vapour. Even when a user is present and observes the reduction, the end point for a reduction is typically judged by eye. The consistency and reproducibility of reduced foodstuffs varies substantially as a consequence.

[5] In other contexts, the cooking temperature of a foodstuff is critical for providing satisfactory cooking end results. However, accurate temperature measurement of a foodstuff is particularly difficult if a user cannot consistently produce the specific cooking conditions that are needed each time, especially in instances where a user is cooking with parts that must be assembled before use. Assembly of parts can ultimately lead to the parts having different respective configurations, and effectively residing in different conditions in each use. Different configurations can confound the accuracy, reproducibility and reliability of the temperature measurements that are made of the foodstuff, which may misinform the user and thereby lead to different end results.

[6] Often in domestic contexts a user of a cooking device may use a first container, such as a pan, (e.g. a saucepan), or similar, on a first occasion in order to prepare foodstuffs. On a second, later occasion, the user may use a second, different container. In induction cooking, since the container itself is responsible for the heating of the foodstuff, a change of container may result in a change of cooking performance, thereby making the reproducibility of the cooking end results challenging. In particular, the user of an induction cooker does not typically know from the outset whether the second container that he or she has selected for use is able to produce cooking results that match those of the first container. Consequently, the user is faced with difficulty in reproducing consistent end results.

[7] In each of the above contexts there is a need for apparatus and methods that assist in overcoming the challenges of providing reproducible cooking. These and other challenges are overcome by the subject-matter of the present invention.

SUMMARY OF THE INVENTION

[8] According to a first aspect of the present invention, there is provided an induction cooker for use with a container for a foodstuff, the induction cooker comprising: a heating component configured, in use, to cause heating of the foodstuff disposed in the container; a sensor configured to measure a parameter of the foodstuff during heating, wherein the parameter is a function of the mass or the weight of the foodstuff disposed in the container; and a controller connected to the sensor and to the heating component, wherein the controller is configured to monitor the parameter and to alter the heating caused by the heating component in response to a change in the value of the parameter. Such an induction cooker is able to respond to automatically alter the heating of the foodstuff in response to a change in a parameter related to the mass or the weight of a foodstuff. Advantageously, the user is not required to intervene to change the heating caused by the heating component when the parameter changes; rather, the controller alters the heating in response to the change. As a consequence, the alteration of the heating occurs without the user monitoring/observing the foodstuff, nor monitoring/observing a measurement that is a function of its mass or weight. [9] In some embodiments, the controller is configured to alter the heating when the value of the parameter is equal to or passes a threshold value. In these embodiments, the controller monitors the transition of the parameter occurring at a specific threshold value. The transition may be passing through a specific value. Alternatively, the threshold may be, for example, a change in the gradient of the parameter (with respect to time), such as a transition through a stationary point; the threshold may be set at the zero of the gradient, or at another point. Whilst either mechanism is suitable, the ‘passing through’ of a threshold can be easier to detect than an equality of a quantity to a specific value, because the ‘passing through’ of a threshold is still detectable even when there exists a drift in the measurement of the parameter, which may occur as components age. The threshold may be a manufacturer-set threshold (i.e. a factory setting) or user-set threshold.

[10] In some embodiments, the controller is configured to alter the heating when the value of the parameter enters or exits a range. The controller monitors the transition of the parameter occurring at one or both ends of a range. The transition may be entering or exiting a range of specific values, or may be, for example be a change in a gradient from a positive to a negative, or vice versa, with the range being a range of gradients. Once again, whilst either is suitable, the transition is between two regimes can be easier to detect than an equality to a specific value. The threshold may be a manufacturer-set threshold (i.e. a factory setting) or user-set threshold.

[11] In some embodiments, the controller is configured to monitor the parameter for a specified change in the value of the parameter and to alter the heating when the specified change in the value of the parameter has occurred. In some instances, the specified change is a percentage change, and optionally, the percentage change lies is the range of ± 10%-90%. In some instances the percentage change lies is the range of ±20%-60% and is optionally either is ± 30%, or ± 40% or ± 50%. In these embodiments, the controller recognises a particular specified change (i.e. a difference between the start value and an end value for the parameter) in order to determine that the required change has occurred, or the controller may recognise a percentage change in the value of the parameter. Specifying a change in this manner mitigates against a situation whereby a range or a threshold is possible but inappropriate for the foodstuff (because that range or a threshold may be set independently of any characteristics of the foodstuff). For example, the controller waiting to act in some instances might result in the foodstuff having undergone an irreversible change. The specified change may be a manufacturer (i.e. a factory setting) or userset specified change.

[12] The parameter may be the mass or the weight of the foodstuff disposed in the container.

Making the parameter directly equal to the mass orweight (i.e. wherein the function is x1) reduces the number of calculations needing to be made by the controller because a direct measurement from the sensor may be used which has a one-to-one correspondence with the change in the foodstuff.

[13] In some embodiments, the sensor comprises a load cell and optionally, the induction cooker has one or more feet and the load cell is disposed in the one or more feet. A load cell provides low power consumption measurement of the mass and weight, avoiding drawing high current from the power supply. Disposing the load cell(s) in one or more feet provides a spacesaving efficiency and avoids the cells needing to be disposed closer to the heating component (the induction coil).

[14] The alteration of the heating caused by the heating component may be a reduction in the heating caused by the heating component, and optionally, the alteration of the heating caused by the heating component may be a deactivation of the heating caused by the heating component. The alteration of the heat may permit the controller to automatically put the foodstuff on to ‘simmer’ and thereby sustain a low level of heating to keep the foodstuff warm. Alternatively, the heating may be deactivated, such that no further heat is caused to be supplied by the heating component, thereby allowing the foodstuff to cool to ambient temperature and preventing over-cooking.

[15] The induction cooker may further comprise an audible or visual alarm to indicate the change in value of the parameter. Such an alarm signals to the user that a change in the parameter has occurred. The automatic response of the controller occurs without user intervention, and since the user need not be monitoring or observing the cooker, the user may continue with other activities. However, the alarm provides an indication to the user that the required change has occurred, and in some instances, may be interpreted as cooking being ‘complete’.

[16] The induction cooker may comprise means configured to enable the user to set the threshold value, or means configured to enable the user to set the range, or means configured to enable the user to set the specified change in the value of the parameter. Such means advantageously permits the user to set the change in the value required for the alteration of the heating to occur, affording the user greater flexibility and meaning that manufacturer-set default changes need not be programmed into the device.

[17] The second aspect of the present invention relates to a tool system for use with an induction cooker, wherein the induction cooker comprises a container for a liquid or fluid foodstuff. The tool system comprises: a first tool for sensing a property of the liquid or fluid foodstuff; a second tool for influencing a property of the liquid or fluid foodstuff; and separation means configured to determine the relative distance between the first tool and the second tool when each of the first tool and the second tool is disposed in the liquid or fluid foodstuff, wherein at least one of the first tool and the second tool is configured to be removably attached to the separation means and/or to the other of the first tool and the second tool. The separation means of such a tool system establishes and maintains the separation between the first tool and the second tool when the tool system is assembled for use with the induction cooker. Such separation means makes the distance between the tools predictable and reproducible between uses, whilst affording the user the flexibility to remove and attach one or other of the tools and disassemble the tools between uses.

[18] In some embodiments, the separation means is further configured to provide the removable attachment between the first tool and the second tool. In such an embodiment, the separation means provides a dual-function of attachment and determination of the relative distance, thereby reducing the number of elements needed in the tool system.

[19] The separation means may be integral with either the first tool or the second tool. Forming the separation means integrally with one or other of the tools reduces the number of assembly steps needed to assemble the tool system for use and provides a fixed relationship between the separation means and one of the tools.

[20] In some embodiments, the separation means comprises a clip to provide frictional or pinching attachment between the first tool and the second tool, and optionally, the clip is made from silicon or acrylonitrile butadiene styrene (ABS). Using a clip to attach the two tools together avoids the need for a third element (such as an adhesive or a screw and nut combination) to provide the means of attachment. Providing a silicon clip ensures that the clip does not degrade when exposed to heat during cooking. Providing an ABS clip ensures that the clip may be straightforwardly injection moulded.

[21] The separation means may be further configured to determine the orientation of the first tool or the second tool with respect to the other tool, when that tool is attached to the separation means. In such embodiments, the separation means may further comprise an orienting recess located on the first tool and configured to cooperate with a portion of the second tool in order to set and maintain the orientation of the second tool relative to the first tool. Alternatively, the separation means may further comprise an orienting recess located on the second tool and configured to cooperate with a portion of the first tool in order to set and maintain the orientation of the first tool relative to the second tool. If the first tool has an optimum relative orientation to provide the most accurate sensing of a property of the liquid or fluid foodstuff, or if the second tool has an optimum relative orientation to provide the most effective influence on a property of the liquid or fluid foodstuff, then the separation means may advantageously ensure that the optimum relative orientation of the tool is achieved. A recess (sometimes referred to as an indent) provides a straightforwardly mouldable element able to cooperate with a portion of a tool that ensure the optimum orientation. The cooperation of the indent or recess and the portion may be visible to the user, or an audible or tactile indication of the cooperation may be apparent (possibly via a ‘click’).

[22] Additionally or alternatively, the separation means may be further configured to determine the location of the removable attachment of the first tool or the second tool to the separation means. In such embodiments, the separation means further comprises a locating recess located on the first tool and configured to cooperate with a portion of the second tool in order to set and maintain the location of the removable attachment between the second tool and the first tool. Alternatively, separation means further comprises a locating recess located on the second tool and configured to cooperate with a portion of the first tool in order to set and maintain the location of the removable attachment between the first tool and the second tool. If the first tool extends an optimum amount in a particular direction (for example, an optimum amount into the liquid or fluid foodstuff) to provide the most accurate sensing of a property of the liquid or fluid foodstuff, or if the second tool extends an optimum amount (for example, an optimum amount into the liquid or fluid foodstuff) to provide the most effective influence on a property of the liquid or fluid foodstuff, then the location of attachment to the separation means sets that extent and ensures that a particular extension is achieved in use. A recess provides a straightforwardly mouldable element able to cooperate with a portion of a tool that ensure a location. The cooperation of the recess and the portion may be visible to the user, or an audible or tactile indication of the cooperation may be apparent (possibly via a ‘click’).

[23] In some embodiments, the orienting recess and the locating recess are the same recess. Advantageously, both the orientation and the location of the removable attachment are set by the same recess cooperating with a portion of a tool, reducing the number of recesses that are needed. Further, since both the orientation and the location are ensured by the same recess and tool portion, a single step in the assembly of the tool system provides sets and maintains both the orientation and location of removable attachment, reducing the number of assembly steps a user must make. [24] In some embodiments, the first tool comprises a sensing element and the second tool comprises an influencing element, and the relative distance between the sensing element and the influencing element is less than or equal to 50mm and optionally, less than or equal to 20mm. Ensuring a maximum separation between the sensing element and the influencing element entails that the influencing of a property of a liquid or fluid foodstuff occurs proximate to the sensing of the property of the liquid or fluid foodstuff, leading to improved accuracy of the sensed property from the first tool whilst the liquid or fluid foodstuff is being the influenced by the second tool.

[25] In some embodiments, the tool system further comprises attachment means for removably attaching the tool system to the container. Such attachment means permits the container and tool system to be moved as one unit during use, and separated thereafter for storage.

[26] In some embodiments, when the container has a rim and a base, the attachment means is configured to attach the tool system to the container such that a fixed distance exists between the base of the container and the first tool or the second tool when each of the first tool and the second tool are disposed in the liquid or fluid foodstuff. In other instances, the attachment means is configured to attach the tool system to the container such that a fixed distance exists between the rim of the container and the first tool or the second tool when each of the first tool and the second tool are disposed in the liquid or fluid foodstuff. In still further instances, the attachment means is configured to do both. Providing a fixed distance (in use) between the base and/or rim of the container and the first tool and/or the second tool ensures a specific geometric relationship between these elements. In some instances, the fixed distance may be between 0mm and 100mm, where 0mm indicates that either the first tool or the second tool abuts the rim/base. The position of the tools relative to the container may influence the sensing of the first tool and/or the influencing of the second tool, and if one or other tool is disposed too far or too close to the base or to the rim, this may lead to an inaccuracy or an inefficiency respectively. Further, providing fixed distances ensures reproducibility because the fixed distance may be established on multiple uses.

[27] In some further embodiments, the attachment means is further configured to determine the orientation of the tool system with respect to the container. Advantageously, such attachment means ensures the reproducibility of a specific relationship between the container, the sensing of the first tool and the influencing of the second tool that may provide consistent operation. In addition to the relative orientation and location of the tools previously described, providing a reproducible orientation and/or location of the tool system relative to the container with the attachment means may improve the accuracy of the sensing and/or the efficiency of the influencing. [28] The attachment means may comprise a clip, and optionally, a biased clip. Further optionally, the clip includes a protruding foot configured to secure the clip arm to the side of the container. Advantageously, a clip offers a simple construction of an attachment means to the container that is easy-to-use. Providing a biased clip aids in frictionally securing the tool system to the container using the attachment means, whilst providing a protruding foot provides a focussed point of contact with the side of the container and aids removal because a gap exists between the clip arm and the side of the container due to the foot.

[29] In some embodiments, at least one of the first tool and the second tool comprises cabling, and at least one of the first tool, the second tool and the separation means comprises cable tidying means to receive a portion of the cabling. The cable tidying means controls the direction of cabling extending away from the tools, thereby keeping the cabling away from other directions (such as being directed across the container).

[30] In some embodiments where the first tool and the second tool comprise cabling, the cable tidying means is disposed on one of the first tool or the second tool. The cable tidying means may further direct the cabling towards the attachment means. Cabling from both of the tools is thus directed in the same direction, and optionally towards the attachment means, improving tidiness. Further, since the attachment means secures the tool system to the container, the cabling is directed towards a specific point of the container.

[31] In some embodiments, the first tool is a temperature sensor and the sensed property is the temperature of the liquid or fluid foodstuff, and/or the second tool is a circulator and the influenced property is the flow of the liquid or fluid foodstuff. Providing a fixed separation between the temperature sensor and the circulator offers a reproducible arrangement that ensures the temperature sensor sits in the same portion of the flow during each use of the tool system, thereby increasing the reliability and comparability of the temperature measurements of the liquid, and consequently leading to more consistent cooking performance.

[32] In some embodiments, one of the first tool and the second tool includes a visible depth marker to indicate, in use, the extent of submersion of the tool in the liquid or fluid foodstuff. The depth marker provides an indication to the user of the level of the liquid or fluid foodstuff in the tool, which may change during use, or may provide an indication showing when the tool is sufficiently submerged. [33] There is further provided an induction cooker or a kit of parts comprising any of the tool systems previously described. There is also provided an induction cooker comprising the kit of parts, wherein induction cooker comprises a housing and wherein the housing is configured to store part or all of the kit of parts when the kit is not in use. Advantageously, storing the parts within the housing of the induction cooker when not in use provides a space-saving solution to storage of the tool system.

[34] A third aspect of the present invention relates to an induction cooker for use with a container for a foodstuff, the induction cooker comprising: a circuit configured, in use, to: apply a signal to the container; monitor a response to the signal; and derive a characteristic of the container based upon the response; wherein the induction cooker further comprises an output means configured to output, to the user, an indication related to the derived characteristic. Advantageously, the induction cooker is configured to interrogate the container’s response to a signal and provide the user with feedback information related to the how the container behaves in response to the signal.

[35] In some embodiments, the signal comprises a drive signal having a drive frequency (which may be pulsed). The circuit is further configured to sweep the drive frequency through a range of frequencies from below a resonance of the container to above a resonance of the container and the characteristic of the container is based upon the monitored response at the resonance. Monitoring the response at resonance provides a derived characteristic related to the resonance. The user consequently receives an indication related to the behaviour of the container at resonance. The user is also given an indication that the induction cooker is able to cook efficiently with that container.

[36] In such embodiments, the circuit may be further configured to determine one or more of: an amplitude, phase or frequency of the drive signal at the resonance; a bandwidth of the resonance; an amplitude of the resonance; a Q-factor of the resonance; or a function of one or more of these parameters. Determining the applied amplitude, phase or frequency of the drive signal enables monitoring to occur based on a quantity set by the drive circuit itself as the drive signal is applied, and enables an indirect indication of resonance. Monitoring the bandwidth, amplitude or Q-factor of the resonance directly monitors the response to the drive signal on resonance. [37] The circuit may be configured to determine the magnetic permeability, or the surface resistance, or the electrical conductivity of the container, or a function of one or more of these parameters, wherein the characteristic of the container is a function of the determined parameter(s). Determining the parameters related to the skin effect in the container provides an indication to the user of the suitability of the container in supporting inductive eddy currents, in dissipating resistive energy and/or for providing a source of hysteresis losses, each of which lead to heat generation in the container.

[38] The output means may be a visual display or may provide an audible indication.

[39] In some embodiments the induction cooker further comprises a memory, wherein the memory is configured to store a container profile, and the container profile associates the container with the indication of the characteristic of the container. Storage of a container profile provides a record of a characteristic of the container that has been analysed by the induction cooker. Advantageously, such a record may assist in maintenance of the induction cooker by providing a record of the containers that have been used for cooking.

[40] The induction cooker may be further configured to upload or download the container profile from a memory, such as a removable storage medium, or from a wired or wireless network. Advantageously, users may receive a container characterisation from another source, despite not having run the container analysis routine themselves.

[41] The induction cooker may further comprise recall means configured to recall a stored container profile. Advantageously, a user may characterise a container on first use, store the profile and recall the characterisation via the profile for subsequent uses, thereby avoiding the need to re-characterise a container a second time.

[42] In some embodiments, the circuit is further configured to adjust the electromagnetic induction to be produced by the induction cooker in response to the characteristic of the container. Advantageously the inductive performance may be optimised on the basis of the characteristic, leading to more efficient cooking.

[43] There is also provided a method of providing a user an indication of a characteristic of a container for a foodstuff for use with an induction cooker, the method comprising the steps of: applying a signal to the container; monitoring a response to the signal; deriving a characteristic of the container based upon the response; and outputting the indication of the derived characteristic to the user.

[44] In some embodiments of the induction cooker or the method, the indication comprises a parameter indicating the suitability of the container for use with the induction cooker, and optionally, the parameter is a dimensionless number. A dimensionless number may be straightforwardly understood by a user and may characterise the container based on a scale (e.g. a number between 1 and 10, where 10 indicates high suitability and 1 poor suitability).

[45] In such embodiments of the induction cooker or the method, the parameter indicating the suitability of the container for use with the induction cooker is provided alongside a message indicating to the user to the suitability of the container. As a result, in addition to the parameter, a warning message or a confirmation of suitability message may be presented. Providing a message alongside the parameter reduces the risk of the user inadvertently misreading one or other indication.

[46] One or more of the steps of the method may be executed by a circuit and optionally, each step of the method is executed by the circuit.

[47] According to a further aspect of the present invention, there is provided an induction cooker comprising a combination of an induction cooker according to the second aspect and either or both of an induction cooker according to the first aspect and according to the third aspect.

[48] According to yet another aspect of the present invention, there is provided an induction cooker comprising a combination of features of the induction cooker of the first aspect and the induction cooker of the third aspect, and optionally, the tool system of the second aspect.

[49] There is also provided a kit of parts comprising: a container for a foodstuff for use with an induction cooker, and the induction cooker or tool system of any preceding aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

[50] The present invention is described below with reference to the following figures, in which:

[51] Fig. 1 is a perspective view of an induction cooker in the closed configuration. [52] Fig. 2 is an upper perspective view of the induction cooker of Fig. 1 , with the external components inside.

[53] Fig. 3 is an upper perspective view of the induction cooker of Fig. 1 with the external components removed.

[54] Fig. 4 is a lower perspective view of the induction cooker of Fig. 1.

[55] Fig. 5 is a perspective view of a boil-over sensor for use with the induction cooker of Fig. 1.

[56] Fig. 6 is a perspective view of a temperature sensor holder for use with the induction cooker of Fig. 1.

[57] Fig. 7 is a cross-sectional view of the induction cooker of Fig. 1 , including the components required for during mass/weight-controlled reduction.

[58] Fig. 8 is a flow diagram of a process executed by the controller of the induction cooker of Fig. 1 during mass/weight-controlled reduction.

[59] Fig. 9 is a perspective view of a disassembled tool system.

[60] Fig. 10 is a perspective view of the assembled tool system of Fig. 9.

[61] Fig. 11 is a perspective view of the tool system of Fig. 10 in use with an induction cooker of Fig. 1

[62] Fig. 12 is an exemplary view of a display shown to the user during operation of the cooker.

[63] Fig. 13 is a flow diagram of a process executed by the controller of the induction cooker of Fig. 1 during container analysis.

DETAILED DESCRIPTION [64] The following detailed disclosure outlines the features of one specific embodiment of the present invention. In addition, some (but by no means all) variants of the specific embodiment that might be implemented whilst still falling under the scope of the present invention are also described. Whilst the following description is subdivided into sections in order to aid the skilled person’s comprehension of the subject-matter, the specific substructure of the detailed description should not be seen as delimiting individual embodiments of the invention. On the contrary, features of the various sections may be combined as appropriate. For example, the load cells 30 used in the “mass/weight-controlled reduction” section may be used in the same induction cooker as boil-over sensor 200. As another illustrative example, the temperature sensor 700 may be used in an induction cooker that can undertake “container analysis”.

[65] Reference to the features shown in each of Figs 1 to 13 should be made in order to understand the principles of the present invention as outlined below. Nevertheless the present invention is defined only by the appended claims.

Definitions

[66] As used herein the term “function of” a parameter, such as in the phrase “function of the mass or the weight”, means that the value of a function is linearly related to the value of the parameter, such that a change in the parameter is reflected by a change in the value of the function. For example, if the parameter is z, the function is f(z) for any suitable f, such as f(z) = 2z, or f(z) = sin z, or f(z) = z², or f(z) = constant x z’¹, or f(z) = constant - z. Alternatively, f(z) may be related to the derivative or integral of z with respect to another variable, such as time t. In some instances, f(z) = z.

[67] When referred to herein, a “change” in the value of a parameter means a reduction in the value of the parameter or an increase in the value of a parameter. One example of such a change is when the parameter is a function of the weight or mass of a foodstuff and a change in the value of the parameter may indicate that the foodstuff has commenced evaporating, has reached a sustained level of evaporation, or has reached a point where evaporation has substantially stopped.

[68] Colloquially in the field of cooking, the weight of an ingredient is often referred to by its mass e.g. ‘50g of butter’ is referred to as a ‘weight’, despite is being a mass. When referring to the mass or weight of a foodstuff herein, except where context dictates otherwise, it is recognised that, whilst strictly mass represents the amount of stuff and weight represents the force exerted by that mass in a gravitational field, the skilled person would understand that in cooking the two terms are used interchangeably to refer to the same thing, and should be understood in same fashion here.

[69] As used herein the term “removably attachable” means that a first element is purposely able to be attached to and separated from a second element. The term is intended to encompass all possible means of removable attachment, and the removal should be non-destructive on the two elements involved.

[70] As used herein the term “foodstuff” is intended to encompass any item of food for consumption, be it solid or liquid, or fluid. By the term “fluid foodstuff” is meant a foodstuff that is able to flow, such as a water, a broth, a sauce or a gel.

[71] As used herein the term “tool” means any element that assists the user in use of the induction cooker in one or more ways. A tool includes elements such as a probe, a utensil, a gadget, appliance or implement that assists in cooking.

Cooker overview

[72] According to an embodiment of the present invention, an induction cooker is shown generally by Figs 1 to 4. As shown in Fig. 1 , the induction cooker comprises a cooker 10 and a base 100 that are separable from each other. The cooker 10 and the base 100 each have a generally cuboidal shape with rounded corners to avoid sharp edges, and together cooker 10 and base 100 form a composite larger cuboidal shape. In Fig. 1 , the cooker 10 forms the upper portion of the composite cuboid, whilst the base 100 forms the lower portion. In this configuration, a temperature sensor 12 is exposed on the upper surface of the cooker 10 (explained further below). In addition, buttons 14 and display 15 are each visible on the upper surface in use. Whilst in the embodiment, the screen is located in a corner, and the temperature sensor 12 is near but offset from the centre of the upper surface of cooker 10, alternative positioning of these elements would be possible.

[73] Buttons 14 are positioned below display 15 and enable the user to interact with the display, to confirm entries and select options that are shown on that display, depending on the mode of operation of the cooker. Buttons 14 are context-sensitive, such that the result of pushing a button 14 is dependent on the displayed output. For example, in some instances the leftmost button might result in entering a new mode, and in other instances, the leftmost button might result in cancelling a previously selected command. Mechanical buttons 14 are used to enable commands to be reliably made, even if a user has (for example) wet hands, which might confound a touchscreen interface.

[74] Display 15 displays information concerning the operation of cooker 10 and provides the user with visual feedback concerning the operation of the cooker. In some instances, the activation of the display 15 may be a ‘power-on’ indicator that shows the user the cooker 10 is ready to receive commands.

[75] The information shown on display 15 may include icons or alerts that indicate the mode of operation, the progress of cooking or a readout of a property of the foodstuff or the container (such as the weight/mass, or the temperature, such as that measured by temperature sensor 12 or temperature sensor 700). The display shows menus and options for the user to navigate through. IN one example, display 15 is an LCD TFT display which sits behind the glass upper surface of the cooker. Further details regarding the display 15 and the user’s interaction therewith will be explained below.

[76] As can be seen from Fig. 4, cooker 10 includes a bevelled bottom portion 16 which protrudes from the opposite site of the upper surface of cooker 10. The cross-section and profile of bottom portion 16 is smaller than that of the upper portion of cooker 10, such that is it able to be accommodated within the raised edges 108 of base 100, as shown in Fig. 2 and 3, and explained below. Whilst bottom portion 16 has a bevelled portion in this instance, other shapes and contours might be used for the bottom portion 16, provided that each shape or contour still permits the bottom portion to be accommodated within the raised edges 108 of base 100.

[77] Bottom portion 16 has one or more feet 18 extending therefrom, on which cooker 10 stands in use. Cooker 10 further includes an air vent 24 on the bottom surface of bottom portion 16. In use, the air vent 24 permits circulation of cooling air to the electronics of cooker 10 (in particular the induction coil), and airflow to the air vent 24 is permitted because the bottom surface of bottom portion 16 is elevated off the surface on which cooker 10 sits by the presence of feet 18. Whilst four feet 18 exist in the instance shown, other examples may an alternative number. The positioning of the feet 18 in the corners or the bottom portion 16 is selected for stability during cooking, but other positions are possible. In addition, the positioning of the feet 18 and their cooperating sockets 102 in base 100 ‘frees’ the remainder of the space in base 100 for cut-outs, as explained below. Whilst the feet 18 themselves form cylinders extending from bottom portion 18, alternative shapes and sizes are possible, such as a series of elongated and/or criss-crossing ridges. Any geometry is acceptable provided that the air flow to vent 24 is not impeded. [78] The cooker 10 encloses the key components, coils and electronic circuits for providing inductive cooking (not shown) of foodstuffs and liquids. The components include a heating component, such as an induction coil, through which an AC current is driven to cause heating in a container placed on top of the upper surface of the cooker 10. As explained in further detail below, the container stands in the changing magnetic field that exists when the AC current is run through the coil. The cooker 10 also encloses the circuits and adapters for supplying power to the cooker components, and a controller 1000 for regulating the operation of the cooker 10. Whilst the heating of the foodstuff occurs due to the heating of the container itself in an induction cooker such as cooker 10, as disclosed herein the induction coil is referred to as the ‘heating component’ because, in use, the coil ultimately results in the heating of a foodstuff disposed in the container.

[79] Cooker 10 is constructed primarily from of a combination of metal, glass and plastic. The uppermost surface of the cooker 10 is made of glass which has a low thermal expansion and poor thermal conductivity. The glass upper surface does not generally heat up very much during cooking. The glass surface protects the components below (such as the display 15). The remainder of the cooker 10 is generally formed of injection moulded plastic (for example Acrylonitrile butadiene styrene (ABS)). The injection moulded plastic of cooker 10 houses the circuits, controllers and electronics and induction coils of the induction cooker, as well as the sockets for receiving the cable connectors to the external components and to the power supply. Both injection-moulded plastics and glass surfaces are straightforward and cheap to manufacture.

[80] As shown in Fig. 1 , the upper surface of cooker 10 has a sprung-mounted temperature sensor 12 which protrudes slightly above the glass surface. In use, when a container for foodstuffs (such as a pan) sits on the upper surface of cooker 10, the container is placed over the temperature sensor 12, such that the base of the container makes contact with the temperature sensitive element of temperature sensor 12, which is in turn pushed slightly into the cooker 10, against the bias of the spring mount. The upper surface of the cooker 10 may include one or more visible markings to encourage the user towards a particular positioning of the container, to thereby ensure contact with the temperature sensor 12. For example, the markings may encourage the user to centre the container over temperature sensor 12.

[81] Whilst not mandatory, in the example, the temperature sensor 12 is located at the centre of the heating component residing in cooker 10. Consequently, the position of the temperature sensor 12 provides a reference for the user that encourages the correct positioning of a container for the most effective coupling between the container and the heating component of cooker 10. Thus the temperature sensor 12 serves a dual role of encouraging correct positioning of the container, alongside temperature measurement.

[82] Spring-loading the temperature sensor 12 and positioning it within the cooker 10 as shown ensures that, in use, the temperature sensor 12 makes constant contact with the bottom of the container, measuring the temperature of the container. This mechanism provides direct feedback on the actual temperature of the container as it heated, rather than via an indirect method (such as setting or monitoring a related characteristic, for example, the power output of the cooker 10). In cooking applications where the temperature of the container is critical for the desired cooking of the foodstuff, direct monitoring provides a more accurate temperature reading to feedback to the user, thereby enabling the user to react as needed to produced consistent cooking end results. Although sprung-loaded in the example, temperature sensor 12 may be mounted on any biasing element that biases the temperature sensor 12 into contact with the container.

[83] In the closed configuration of Fig. 1 , the cooker 10 connects to the base 100, and together the cooker 10 and base 100 provide a housing 50 for the external components of the induction cooker. The external components of the induction cooker are shown in Figs 2 and 3, and include a boil-over sensor 200, a power plug 300, a temperature sensor holder 400, a dial 900, a circulator 600 and a temperature sensor 700. Housing 50 prevents access to the external components before the induction cooker is opened, permits space-saving storage of the external components, and transportation of the cooker 10, base 100, and the external components as a single unit.

[84] In the closed configuration, the cooker 10 and base 100 are held together via feet 18, which extend from bottom portion 16. Feet 18 cooperate with sockets 102 on base 100 to secure the cooker 10 to the base 100. Positioning the feet 18 in the sockets 102 aids in preventing lateral and rotational movement of the cooker 10 with respect to base 100 because each foot 18 is surrounded by the socket 102 and fits snugly there within. In addition, one or more magnets are placed within base 100 adjacent to the sockets 102 to magnetically secure corresponding magnetic materials in the feet 18 into sockets 102. Inadvertent vertical movement of the feet 18 into and out of sockets 102 is magnetically resisted and only when sufficient force is provided by the user to overcome the magnets does the connection between the sockets 102 and the feet 18 break, such that cooker 10 and base 100 may be separated. Further, whilst a magnetic configuration is described, other means, such as clips, or a hook and loop fastening, may be used to ensure a secure connection between the cooker 10 and base 100. [85] As shown in the open configuration of Fig. 2, base 100 includes raised edges 108 that are configured to cooperate and surround bottom portion 16 of cooker 10 when in the closed configuration of Fig. 1. Having bottom portion 16 accommodated within base 100 in the closed configuration reduces the thickness profile of induction cooker in storage. Raised edges 108 cooperate with the bottom portion 16 to prevent lateral or rotational movement of the cooker 10 with respect to the base 100. Raised edges 108 further include notches 109 to accommodate the external component connectors 20 and power socket 22 which are positioned on the side of cooker 10. When in the closed configuration, the raised edges 108 of base 100 occlude the external component connectors 20 and power socket 22 of cooker 10, preventing connections being established and therefore preventing use of the cooker 10 whilst it sits on the base 100. This is advantageous because were cooker 10 to be used on the base 100, air flow to air vent 24 would be prevented, risking overheating of the cooker and its internal circuits. In the present instance, raised edges 108 have a triangular cross section extending upwards above the deck surface 111 of the base 100. The triangular cross-section cooperates with the bevel of bottom portion 16 to provide a snug fit. However, alternative cooperating geometries may be used for bottom portion 16 and raised edges 108. Further, features such as nibs, ridges or protrusions may be included in one or other of the raised edges 108 and bottom portion 16, and corresponding indentations and recesses adapted to receive the nibs, ridges or protrusions be include on the other of the raised edges 108 an bottom portion 16, to additionally secure the bottom portion 16 and raised edges 108 together in the closes configuration.

[86] Base 100 includes cut-outs 104 that are sized and shaped based on the ‘main body’ of each external component and which are each configured to receive an external component. Each cut-out secures the external components within the housing 50 in the closed configuration, and each cut-out has a unique configuration that means only one of the external components will fit therein. Each of boil-over sensor 200, power plug 300, temperature sensor holder 400, dial 900, circulator 600 and a temperature sensor 700 has its own respective cut-out 104 in which it may reside in base 100 when not in use. One or more cut-outs 104 include at least one finger hole 106 to assist in removal of the external components from the cut-outs 104 for use.

[87] Each external component is configured to fit tightly into its respective cut-out 104 and is frictionally secured therein, except for power plug 300, which is held in place in a generally larger cut-out 105 by cross bar 220. The cabling for each of boil-over sensor 200, circulator 600 and temperature sensor 700 is also held in the larger cut-out 105. Between the larger cut-out 105 and the cut-outs 104 in which the respective external components fit, the cabling runs along a respective cut-out or trench. Cross bar 220 holds the cabling in the larger cut-out 105; cross bar 220 has its own cut-outs into which cross bar 220 is frictionally secured, although the cross bar may instead be secured by fastening means, or may be secured magnetically. Cross bar 220 prevents the cabling from falling out of the larger cut-out 105. In the example, and due to the larger cut-out 105 and cross bar 220 used for the cabling, the user is not required to frictionally fit one or more cables into otherwise narrow cut-outs, but rather may ‘loop’ them into the larger cutout 105 as shown in Fig. 2. Such an arrangement has several advantages, including saving time when replacing the external components into the base 100, and avoiding the need to force a cable into a specific configuration (because it may simply be ‘looped’ as shown). ‘Looping’ the cabling as shown avoids placing undue stress on the cabling during storage, and also during insertion and removal of the external components. Other cut-out geometries that are suitable for securing one or more external components (such as tools) is the base, and the particular geometry shown is only exemplary. In addition, other securing mechanisms, such as the magnetic mechanism used by the feet 18 and sockets 102, may also be used to secure one or more external components into the space in base 100.

[88] Shortly after use, each external component may be warm. Since base 100 is substantially constructed of cork, the base 100 is heat resistant and may absorb residual heat from the external components when those components are returned to the base 100 after use.

[89] Power plug 300 is a conventional power supply, typically fitted with a fuse. The power supply includes pins that are configured, in use, to connect to power socket 22 on cooker 10 at one end of the cable, and to plug into a standard mains supply at the other end of the cable. In the particular configuration shown, the ‘head’ of power plug 300 includes 3-pins and has its own cut-out, connected to the larger cut-out previously described.

[90] Each of boil-over sensor 200, circulator 600 and temperature sensor 700 includes a connective cable to transmit a signal between the boil-over sensor 200, circulator 600 and temperature sensor 700 and the controller 1000 and/or circuit within the cooker 10, and/or to transmit power to the respective external component as necessary. Cable connector 200c sits at the opposite end of the cable from the boil-over sensor 200. Cable connector 600c sits at the opposite end of the cable from the circulator 600, whilst cable connector 700c sits at the opposite end of the cable from the temperature sensor 700. Each of cable connectors 200c, 600c and 700c is configured to be operably connected to a respective one (and only one) of subconnectors 20a, 20b or 20c of external component connector 20. For example, cable connector 200c of the boil- over sensor 200 is configured to be received in only one of the subconnectors (say 20a), and cable connector 200c is incompatible with the other subconnectors (say 20b, 20c). Such an arrangement advantageously prevents a user from inadvertently misconnecting the boil-over sensor 200 to the ‘wrong’ subconnector of external component connector 20, which might render the boil-over sensor 200 inoperable, or even might damage the cooker 10, its controller 1000 or the internal circuits, or the boil-over sensor 200. A similar arrangement provides the same advantage for cable connectors 600c and 700c.

[91] In the specific embodiment, the unique connections above are achieved by magnetic subconnectors 20a, 20b and 20c, each having a unique number of pins or male portions and cooperating with cable connectors 200c, 600c and 700c having the corresponding number of recesses or female portions. It is also possible to provide the male portions on the cable connectors and the female portions on the subconnectors, or a mix of the two. Alternatively, different shaped or sized housing of the connectors may be used to assist the user in differentiating between subconnectors, or the connectors may connect instead to separate locations around the cooker 10, rather than at single component connector 20. Alternatively, the correct pairings of subconnectors and cable connectors may be based on one or more symbols, words or on colour-coding. However, one advantage of the exemplary arrangement is that the subconnectors and cable connectors is that a connection cannot be established between an incompatible subconnector and cable connector.

Boil-over sensor

[92] A boil-over sensor is sensor that is configured to be attached a container that is placed on the induction cooker and to provide a signal indicative of the level of a foodstuff (such as a liquid or fluid foodstuff) in the container during heating. The boil-over sensor is configured to be connected to the controller of the induction cooker and in response to the signal indicative of the level provided by the boil-over sensor, the controller alters the heating caused by the heating component of the induction cooker. The advantage of a boil-over sensor is that the user might not be present to reduce the heating to prevent the liquid or fluid foodstuff overflowing, but nevertheless, the cooker may react to prevent such an occurrence. Avoiding boiling over is important, especially when the volume of the liquid or fluid foodstuff is important to the cooking end result, since it is typically unknown how much volume is lost during a boil-over.

[93] Boil-over sensor 200 as shown in Fig. 5 is an example of a boil-over sensor. Boil-over sensor 200 is a generally ‘U-shaped’ external component that is configured, in use, to attach to the rim of the container that contains a liquid or fluid foodstuff that might boil-over. The rim of the container is configured to sit between the two ‘legs’ 202 of the U-shape. Each leg 202 of the U- shape includes a contoured section 204 configured to maintain placement of the legs against the rim/sides of the container to frictionally hold the boil-over sensor 200 in place. [94] In the example, boil-over sensor 200 includes a magnetic 4-pin cable connector 200c to attach to subconnector 20a of cooker 10 that is connected to the U-shaped portion by a cable. As an alternative, a 5-pin connector might also be used. Except for the sensitive element, the boil- over sensor is generally encased in silicon for heat resistance, although other materials are possible.

[95] The boil-over sensor 200 includes a sensor that may directly sense the steam or foam given off by the liquid or fluid foodstuff as it approaches boiling, or which senses the level of the liquid or fluid foodstuff itself. Alternatively, the boil-over sensor may be a mechanical sensor that responds to the vibrations (including those in the container) that are produced by the heated liquid or heated fluid foodstuff, which indirectly indicate the level of the liquid or fluid foodstuff in the container.

[96] Boil-over sensor 200 is configured to be connected to the controller 1000 of the induction cooker 10 and to provide a signal to the controller that either directly or indirectly represents the level of the liquid or fluid foodstuff in the container. When the level of the liquid or fluid foodstuff is high enough, there is a risk of the liquid or fluid foodstuff ‘boiling over’ because the level is too close to the rim of the container. In response to the signal, the controller 1000 compares the signal to a pre-established criterion, such as a threshold distance of the level from the rim (e.g. 15mm). If the result of the comparison is too close to the rim and boil-over might occur, controller 1000 alters the heating caused by the heating component, typically to reduce the temperature, and thereby avoid the boil-over occurring. The criterion used for the comparison may be established by the user during set up, or may be factory set.

Circulator

[97] As shown in part of Fig. 9, circulator 600 includes a generally cylindrical housing 602, including an upper section 602a and lower section 602b. Circulator 600 comprises part of tool system 2000 described below.

[98] Mounted on upper section 602a is an example of an attachment means 604, in the form of a clip 606. Clip 606 is configured to attach the circulator 600 to a container in use, over the rim of the container. Clip 606 includes arm 608 and protruding foot 610. Clip 606 is pivoted about axis A. Clip 606 is resiliently biased in a direction that biases foot 610 to contact housing 602. The bias is provided by a spring (not shown), although alternative forms of biasing, such as a resilient band or member might be used. Foot 610 at the end of arm 608 is sized and oriented to create a gap between arm 608 and the housing 602 of the circulator 600, into which a user’s fingers fit in order to aid removal and provide purchase for arm 608 about axis A.

[99] Providing clip 606 (or in general, attachment means 604) enables circulator 600 to be attached to the container in a specific and reproducible geometric relationship with respect to the container. As a consequence, the resulting elements of the circulator 600 have a specific relative location with respect to the container’s side and rim, each time the circulator 600 is used. Since the performance of the circulator and its ability to influence the flow are affected by the proximity of the side of the container and the objects that surround it, attachment means 604 provides a reproducible location for the circulator 600 and enables the circulator 600 to provide a consistent performance, each time that it is used.

[100] Lower section 602b of housing 602 is a substantially hollow cylinder, made from stainless steel (although other materials, such as aluminium or plastic would be suitable). Lower section 602b of housing 602 includes a plurality of inlet apertures 612 (e.g. 10 inlet apertures) arranged circumferentially around the lower section 602b, and a plurality of outlet apertures 614 (e.g. 10 outlet apertures), also arranged circumferentially around the lower section 602b, as further explained below. In alternative embodiments, a different number of inlet apertures may be provided and a different number of outlet apertures may be provided. In some instances, only one inlet aperture and or one outlet aperture is provided. Further the number of inlet apertures need not equal the number of outlet apertures. Additionally the inlet apertures and outlet apertures need not be arranged circumferentially around the lower section. For example either set of apertures may trace a helical pattern, or a zig-zag pattern, dependent on the desired flow around the impeller.

[101] Upper section 602a of housing 602 includes a motor (not shown). The motor is disposed within in an injection moulded plastic section, and the motor is subject to water-proofing (and more generally liquid-proofing) treatment. The motor is connected via a drive shaft (not shown) to an impeller (not shown) which is disposed within the lower section 602b of housing 602. The inlet apertures 612 and outlet apertures 614, impeller and drive shaft are arranged such that the impeller is connected to the drive shaft/motor and is disposed within the lower section 602b, between the inlet apertures 612 and outlet apertures 614. In the example arrangement, the drive shaft is elongated in the direction of the lower section 602b and supports the impeller in a location level with the outlet apertures 614.. In some orientations, the drive shaft (although not shown) is visible through inlet apertures 612. In use the impeller is spun by the drive shaft about an axis parallel to the elongated direction of the lower section 602b. Alternative locations, orientations and spin directions for the impeller would also be possible, especially if promotion of different flow regimes is desired.

[102] In use, when the circulator is disposed in a liquid or fluid foodstuff, the inlet apertures 612 and outlet apertures 614 are at least partially submerged below the level of the liquid or fluid foodstuff. Activating the motor causes the drive shaft to rotate and thereby causes the impeller to rotate. Rotation of the impeller expels liquid or fluid foodstuff out of the hollow lower section 602b via the outlet apertures 614. Since the expelling creates a lower pressure close to the impeller, the impeller draws in liquid or fluid foodstuff into the hollow of lower section 602b via the inlet apertures 612. This movement of the liquid or fluid foodstuff encourages flow and circulation of the liquid or fluid foodstuff, both within the lower section 602b and outside of the circulator 600. The circulation of the liquid or fluid foodstuff encourages heat to distribute throughout the liquid or fluid foodstuff.

[103] Circulator 600 includes a magnetic 3-pin cable connector 600c to attach to subconnector 20b of cooker 10 that is connected via a cable to the top end of upper section 602a (cable shown in Fig. 2). The cable provides the power supply to the motor. Circulator 600 further includes a cable tidying means 630, through which the cabling runs and which directs the cable away from the top end of the upper section 602a, such that the cable extends towards the rim of the container and towards and over clip 606. The cable tidying means 630 is an injection moulded generally triangular piece disposed on the top end of upper section 602a. The triangular shape of the cable tidying means that the cable is directed by the triangular piece in a specified direction away from the centre of the container, over clip 606, without placing undue stress on the cable itself. This arrangement is shown in Fig. 11. Although a generally triangular cable tidying means is provided in the example, other geometries would be suitable, such as a curved geometry, which would also avoid undue stress on the cable.

[104] Upper section 602a further includes a silicon clip 652 which enables the temperature sensor 700 to be removably attached to circulator 600 via a frictional attachment. Upper section 602a also includes indent 654 in an upper end thereof. The indent 654 is an example of a recess, and is sized and shaped to receive end portion 704 of temperature sensor 700. Further advantages of clip 652 and indent 654 which comprise portions of the separation means, will be explained in detail in reference to the tool system 2000 below.

[105] In some embodiments, the circulator includes one or more visible depth marker(s) to show the extent of submersion in use. The depth marker may be shown on the outer surface of lower housing 602b. [106] Whilst attachment 604 is in the form of a clip 606 in the specific embodiment, alternative attachment means that provide a reproducible location for the circulator 600 with respect to the container would be possible, such as a U-shaped extension similar to the geometry of the boil- over sensor 200, or a magnetic attachment means.

[107] Any variety of motor is suitable for inclusion in the circulator. Alternatively, a different rotating actuator may attach to the drive shaft to provide rotation of the impeller. Further, the connection between the motor and the drive shaft may incorporate one or more gears. Controller 1000 may include a control mechanism to set the speed of the rotation of the impeller. This speed may be set by the user, or selected from a series of pre-sets.

[108] Also shown in Fig. 9 is temperature sensor 700. Temperature sensor 700 is a tool used to directly measure the temperature of any foodstuff into which the probe point is disposed. Temperature sensor 700 includes an elongated cylindrical main body 706 that converges to a probe point at a one end, the probe point including a thermocouple as the temperature sensing element 702. At the opposite end to the probe point, the temperature sensor 700 includes an end portion 704 that is bent at an angle to the direction of the elongated axis of the main body 706. At the end of the bent section, and at the opposite end to the probe point, cabling carries the signal from the temperature sensor 700 to a magnetic 2-pin cable connector 700c, which is configured to be connected to subconnector 20c of cooker 10 when used.

[109] In some alternative embodiments, the temperature sensor 700 includes one or more visible depth marker(s) to show the extent of submersion or penetration of the sensor during use.

[110] In some circumstances, temperature sensor holder 400, as shown in Fig. 6, is used to attach temperature sensor 700 to the side of a container, thereby permitting the temperature sensor 700 and container to be moved as a single unit during use. Temperature sensor holder 400 is made from moulded silicone and includes three slots 402, 404 and 406. The first slot 402 is configured to receive and frictionally retain the holder 400 on the side a container. The slot 402 includes a central hole 403 configured to accommodate the folded over lip or rim of a container, if such a rim or lip is present. The inner surface of slot 402 includes protrusions designed to grip the side of the container in use, beneath the lip/rim. [111] The second slot 404 has the shape of a semi-circular cut-out. The second slot 404 is configured to permit the elongate main body 706 or end portion 704 of temperature sensor 700 to be frictionally secured between the jaws of the slot, but to do so whilst extending at any angle of declination from the holder 400 into the container, when the holder is positioned on the rim of the container in use. The user is thus afforded greater flexibility in orienting the temperature sensor 700, whilst securing the temperature sensor 700 between the jaws of the slot.

[112] The third slot 406 is a configured to secure the temperature sensor 700. The third slot 406 is configured to permit the elongate main body 706 or end portion 704 of temperature sensor 700 to be frictionally secured between the jaws of the slot. The slot 406 and is truncated by a substantially flat surface 408 which, in use, is able to accommodate the lid of a container. If the container has a lid, the rim of the container lid may rest upon the surface 408. Hence the rim of the container may maintain a position close to the lip or rim of the container being accommodated in the central hole 403, the separation of the rim and lid being only the radial distance between central hole 403 and the surface 408. Providing the surface 408 advantageously minimises the gap between the rim of the container lid and the rim container, which may be desirable during cooking to reduce the loss of vapours.

[113] Whilst temperature sensor holder 400 provides three slots with specific purposes, alternative temperature sensor holders may be provided having a fewer or greater number of slots, and/or having different configurations of slots, whilst still having the purpose of securing the temperature sensor in one or more orientations, and such that the container and temperature sensor 700 may be moved as a single unit.

Built-in scales

[114] As is shown in Fig. 7, cooker 10 includes four load cells 30, one located in each of the feet 18 that extend from the bottom portion 16 of cooker 10. The load cells 30 enable the induction cooker to act as a set of scales, enabling the user to measure the mass or weight of items such as foodstuffs disposed in a container during cooking. Whilst the present cooker 10 includes four load cells 30 of which two are shown in Fig. 7, a different number of load cells or differently positioned load cells may also be used and still enable measurements of the weight or mass to be made.

[115] In order to provide a measurement of the mass or weight, each of the load cells 30 are configured in a Wheatstone bridge arrangement. In some instances, the controller 1000 of cooker 10 may receive a measurement from each of load cells. From the raw measurements the controller 1000 uses the mean of the four measurements to determine the mass or weight of the foodstuff being added. Once the mean of the measurements has been determined, the controller 1000 causes display 15 to show the measurement to the user. In alternative configurations, the modal or median value may be used. In another configuration, only a subset of the load cell measurements is used and may be displayed.

[116] The process of receiving measurements, calculating the mean and displaying the result on display 15 may occur repeatedly, with the display 15 being updated in near real-time as (for example) a foodstuff is placed into a container on the cooker 10.

[117] In further alternative configurations, a consistency analysis is performed by controller 1000 before displaying the weight/mass on the display 15. During such an analysis, the controller looks to see if the reading from any one load cell is substantially different from the other load cells, for example by considering the standard deviation of the measurements. If an outlier exists, the controller either takes a further measurement from the load cell whose measurement is substantially different, or discards that measurement and calculates the average on the basis of the remaining three measurements. In this way, the controller 1000 may perform an error check, and may keep a record of any errors in memory. Such records may be recalled during servicing and maintenance.

[118] When a user is operating cooker 10 whilst setting up a cooking mode, or at other times, the user interacts with cooker 10 via one or more of dial 900, buttons 14 and display 15. The combination of these elements enables the user to control the operation of the induction cooker, by providing interactive menus that a user may navigate to select a cooking mode, to set parameters in order to set up the cooking mode, and to control the functions of the cooker 10. During cooking, the user may similarly interact with the dial 900 or buttons 14 to alter a parameter, change a setting or to receive an update on the progress of the cooking.

[119] In some examples, controller 1000 operates a timer whereby, in the absence of any interaction with the user via dial 900 or buttons 14, the display 15 is deactivated to a ‘standby’ mode and thereby saves energy. At the point at which a user moves dial 900 or presses a button 14, the display 15 reactivates. [120] The dial 900 is a detachable magnetic dial made of metal or injection moulded plastic that is magnetically coupled to the cooker 10 in use (located as shown in Fig. 11), and is stored in base 100 between uses in its own cut-out 104. Dial 900 is placed on a portion of the glass upper surface of the cooker. In the present example dial 900, once placed on the portion of the glass, contains a magnet that interacts with a series of Hall sensors located within the cooker 10 beneath the portion of the surface.

[121] Placing dial 900 on the upper surface may switch on display 15 and start up the cooker 10, the presence of the dial 900 triggering a voltage in the Hall sensors that is detected by controller 1000. Alternatively, the cooker 10 may be started by a rotation (rather than the placement) of the dial 900 to begin, or by the user pressing any one or a combination of buttons 14. In each case, the display 15 may show start-up or welcome messages to the user, or warning messages if the cooker 10 has an error condition, and/or a confirmation that everything is operating within normal parameters). Further alternatively, the display 15 may react to the user plugging in the cable for an external component into to one of subconnectors 20a, 20b or 20c, or the power socket 22.

[122] Once the dial 900 is placed and the display 15 switched on, the user may interact with the device and may navigate the menus and select options. In this context, when navigating the menus, the dial 900 may be used to scroll through options (or alternatively, one or more of the buttons may be used to scroll) and one or more buttons 14 used to select a desired option. Buttons 14 are context sensitive, and may be used to select a different option, depending on the menu shown on display 15 and/or on the cooking mode.

[123] For any menu, turning dial 900 in a clockwise direction will scroll through the menu in one direction, whilst turning the dial 900 in an anti-clockwise direction will scroll through in the opposite direction. By rotation of the dial 900, the user may scroll through operating menus of the cooker 10, and may increment or decrement counters, or increase/decrease the length of objects on the screen (e.g. progress bars or symbols). As dial 900 is moved, the display 15 updates in real-time to reflect the user’s movements of the dial 900. Once a desired menu selection, option or count has been reached, the user may press one or more of buttons 14 to confirm a selection. In some instances, as the dial 900 is turned, the display 15 shows a ‘currently highlighted option’ that changes as the user navigates the menus. If a button 14 is pressed whilst that option is highlighted, the displayed mode, parameter or otherwise is selected.

[124] Display 15 shows words, numbers, phrases and symbols that enable the user to interact with the cooker 10, both during setup and during cooking. For example, a symbol representative of a particular cooking mode may be presented to the user whenever a setting or parameter is being provided by the user, and/or whenever cooker 10 is being operated in a specific mode. Display 15 may further present timers, temperatures (both current and target), weights/masses and other similar parameters, and warnings/errors to the user during operation in each cooking mode.

[125] One illustrative example of the display during a cooking mode is shown in Fig. 12. The display includes a heading to indicate the current mode of the cooker 10 , (a ‘slow cook’ mode, explained below), a symbol to illustrate the external components that are in connected to the subconnectors during that mode (temperature sensor 700, connected via cable connector 700c to subconnector 20c), a timer, which includes an elapsed time and a total cooking time, alongside a circular progress bar, and a temperature target and current temperature measurement, alongside a further circular bar that indicates how close to the target temperature the current temperature lies. The total elapsed time and the target temperature would have been entered by the user previously during setup.

[126] In addition, four context sensitive options are shown at the base of display 15, one for each button 14, labelled MODE, ADJUST, STOP and PAUSE, to enable the user to control the function of cooker 10. Pushing the button 14 closest to the displayed label selects that option. The user may select a different mode of cooking by pushing the button 14 below MODE, may adjust the parameters associated with the current mode by pushing the button 14 below ADJUST or may stop or pause the cooking mode by pushing the buttons 14 closest to STOP or PAUSE respectively. In some instances, fewer than 4 options would be presented to the user. Pushing a button 14 that lacks a corresponding option would either have no effect, or an audible or visible alert to the user would be provided to indicate that in the present context that button 14 has no effect.

[127] Cooker 10 further includes controller 1000. Controller 1000 may be in the form of a processor, microchip or microprocessor, ASIC or programmable array that is configured to receive and interpret signals from the sensors of cooker 10, from dial 900 and buttons 14 and from the external components associated with the cooker 10 when those components are connected by subconnectors 20a, 20b and 20c. In some circumstances, the controller 1000 is also configured to issue commands that affect the operation of the cooker as a response. Controller 1000 may include a memory (which may be solid state memory, or otherwise), and a bus. The programming of the controller 1000 enables the controller to execute the various processes described herein. Controller 1000 also includes an input/output capability that controls the operation of the display 15 and responds to buttons 14 and dial 900, which form interface by which the user controls the cooker 10.

[128] In some instances, cooker 10 includes a means for controller 1000 and its programming to be upgraded after it has been manufactured (for example, in an ‘after sales’ environment), to thereby have settings, functionality or modes loaded onto it from an external source, such as a wired or wireless interface, a network connection or similar. Such upgrades may be to existing modes/functions, or may provide entirely new modes/functions enables the cooker 10 to be adapted for extra functionality after initial manufacturing, affording the user greater flexibility in operation, and in the future expanding flexibility in operation. Alternatively, cooker 10 might include a USB port to permit new operational modes to be loaded onto the device from a removable USB memory stick.

Cooking modes

[129] Using the dial 900, display 15 and buttons 14, the user may select a variety of different cooking modes for cooker 10. Some (but by no means all) of these modes are outlined in greater detail below.

[130] One mode the user may select is a ‘slow cook’ mode, which makes use of temperature sensor 12 and one external component: temperature sensor 700. During this mode, the temperature sensor 700 is placed with its thermocouple 702 (at the probe point) disposed in a foodstuff sitting inside the container. The pointed end of temperature sensor 700 assists in penetration of the foodstuff if necessary.

[131] During setup, a user enters a foodstuff target temperature and a cooking time, such as the target temperature and cooking time shown in Fig. 12. Once cooking commences, the temperature sensor 700 measures the temperature of the foodstuff and provides an indication to the controller 1000 of the current temperature of the foodstuff (and also to the user on the display 15) as shown in Fig. 12. The goal of the slow cook mode is to ensure that the temperature of the foodstuff stays within a desired range, or above/below a certain threshold, based upon the target temperature. If the temperature sensor 700 indicates that the current temperature is outside the desired range, or below/above the target value, the controller 1000 alters the heating caused by the heating component (the induction coil) accordingly to change the increase or decrease the heating of the foodstuff and thereby alter the temperature of the foodstuff detected by the temperature sensor 700 in a direction back towards the target temperature. During this process, controller 1000 receives the temperature measurement from temperature sensor 700 periodically, and compares that measurement with the foodstuff target temperature input during the setup of the mode and a threshold that is set or range that has been set. The advantage of this process is that no monitoring by the user is needed, and the controller 1000 simply responds to the temperature measurements as needed (although audible or visible changes of the actions taken by controller 1000 to alter the heating caused by the heating component may be provided).

[132] Concurrently with the monitoring of measurements from temperature sensor 700 and any ensuing altering of the heating by controller 1000, controller 1000 also receives a temperature measurement from temperature sensor 12, which provides an indication of the temperature of the base of the container (which may also be displayed to the user on the display 15). In order to avoid burning the foodstuff to the base of the container, the container must not exceed a separate container target temperature. Temperature sensor 12 measures the temperature of the container and provides an indication to the controller 1000 of the current temperature of the container. Controller 1000 alters the heating caused by the heating component as needed if the container temperature is too high and is likely to cause burning. In addition, an audible or visual indication may be provided to the user of the risk of burning.

[133] The foodstuff target temperature and the container target temperature may be independently set by the user during setup. Alternatively one may be calculated by the controller 1000 automatically, on receipt of information by the controller, for example, based on the nature of the foodstuff being cooked (for example, by looking up a target temperature from a database or lookup table stored in the memory. Alternatively, one target temperature may be set up automatically based on a given difference with respect to the other target temperature, such as having the container target temperature 5 degrees greater than the foodstuff target temperature.

[134] A second mode that the user may select is a ‘probe cooking’ mode, which is typically used for solid foodstuffs, such as a piece of beef steak. The temperature sensor 700 is pushed into the centre of the foodstuff, aided by its penetrative point. Once again, during setup, a user enters a foodstuff target temperature, and possibly a container target temperature. In similar fashion to the ‘slow cook’ mode outlined above, the controller 1000 monitors the measurements taken by temperature sensor 12 and temperature sensor 700, and reacts if certain conditions are met.

[135] During cooking, controller 1000 alters the heating caused by the heating component to ensure that a target container temperature is reached and maintained, based on the measurement from temperature sensor 12. Meanwhile the temperature rise within the foodstuff is measured using temperature sensor 700. When the foodstuff has reached the target foodstuff temperature as measured by temperature sensor 700, controller 1000 causes cooker 10 to either alert the user (audibly or via display 15), or alter the heating caused by the heating component, or both. In some instances, the alteration of the heating may be to reduce the heating to zero. An indication of that the foodstuff has arrived at the target temperature may be provided to the user.

[136] A third mode the user may select is ‘rice cooker’ mode. During setup and after selecting the mode, a user places a measured amount of rice in a container on the upper surface of the cooker 10 and submerges the rice with water (or liquid in general) for cooking.

[137] The rice cooker mode seizes upon the fact that whilst water surrounds the rice, the temperature of the bottom of the container will not exceed the boiling point of water. Once the rice has absorbed the water, the temperature of the container quickly exceeds the boiling point of water, and therefore monitoring the transition between the two regimes offers an indication of the rice having absorbed the water.

[138] Once cooking has commenced, controller 1000 periodically receives measurements of the temperature of the container from temperature sensor 12 and monitors the progression of the temperature over time. Controller 1000 monitors the temperature measurements for a sudden change (i.e. a spike) in temperature. Once detected, the controller 1000 causes cooker 10 to either alert the user (audibly or via display 15), or alter the heating caused by the heating component, or both.

[139] A fourth mode that the user may select is the ‘sous-vide’ mode, explained in greater detail in connection with the tool system 2000 below. During setup, a foodstuff is placed inside a further container/pouch (such as a plastic bag) and that further container is placed within the (main) container. The (main) container is then surrounded by a liquid or a fluid foodstuff, such as water. The temperature sensor 700 and circulator 600 are assembled into tool system 2000. The user selects a target temperature and cooking time.

[140] During cooking the temperature sensor 700 measures the temperature and the controller 1000 periodically monitors the temperature measurements received. The heating caused by the heating component is altered if the temperature deviates from the target temperature. The accuracy of the temperature measurements is ensured by using the tool system 2000. Once the cooking time has elapsed, the controller 1000 causes cooker 10 to either alert the user (audibly or via display 15), or alter the heating caused by the heating component, or both. [141] A key benefit of each of the cooking modes above is that the controller 1000 is configured to act to alter the heating when an appropriate condition has been detected, thereby preventing over-cooking or under-cooking of the foodstuff. The action of controller 1000 does not depend on the user intervening, although the action may be accompanied by an alert to the user. By acting upon the existence of the appropriate condition, foodstuffs may be cooked with precise control in each instance which aids consistent cooking end results and improves reproducibility.

[142] In each of the modes, the controller 1000 is further configured to alert the user if an error condition exists. An error condition might be a rapid decrease in temperature, indicating that the heating caused by the heating component has ceased or malfunctioned. An alert may be an audible or visible alarm. Alternatively, an error may be a failure of the controller 1000 to receive a measurement from temperature sensor 12, temperature sensor 700, boil-over sensor 200 or load cell 30. In each of these scenarios, if the user is not alerted to the error condition, the foodstuff may be ruined.

[143] The initiating of the alert may also trigger a timer to begin and to run for a specific interval (such as 60 seconds). After that interval has elapsed, and if the user has not interacted with cooker 10 during the interval, the cooker 10 deactivates itself. An interaction by the user may be detected, for example, by the push of a button 14, the rotation of dial 900 or a reduction in the weight/mass detected by load cells 30 (indicating that the container has been removed from the cooker 10).

Mass/weight-controlled reduction

[144] The following passages refer to an example of a ‘reduction by weight’ mode, and the passages will exclusively refer to a reduction by weight mode. However, this will also be considered equivalent to a ‘reduction by mass’ mode and the operation of a reduction by mass mode is envisaged to be substantially identical to a reduction by weight mode. Bearing in mind the colloquial interchangeability of the terms ‘mass’ and ‘weight’ in a cooking context, the skilled person will appreciate that masses might be referred to as weights, and vice versa.

[145] The ‘reduction by weight’ mode of the induction cooker is an arrangement that permits accurate reductions of foodstuffs, such as sauces, broths, soups, juices, wines, stocks and similar liquid or fluid-like substances in a manner that does not require the user to monitor the process to produce consistent results. The reduction by weight mode also provides easily reproducible reductions based on a set of initial parameters, which aids in the consistent reduction of foodstuffs.

[146] Preparations that involve reductions include consommes, gravies, gastriques and sauces and syrups. During reduction, the heated foodstuff is thickened by either or both of simmering or boiling, and the concentration of the foodstuff is intensified by evaporation of vapour from the foodstuff. Whilst reduction concentrates the flavours left in the container, too much reduction can leave a burnt coating on the container because too much vapour has been driven off.

[147] Cooker 10 is able to operate in a reduction by weight mode. Fig. 7 shows a schematic cross-sectional view of an arrangement of an induction cooker operating in the reduction by weight mode. As previously indicated, cooker 10 includes an induction coil as a heating component that causes indirect heating of a foodstuff in the container. As also indicated above, cooker 10 includes four load cells 30, one located in each of the feet 18 that extend from the bottom portion 16 of cooker 10. The load cells 30 form a means of sensing weight changes on the cooker 10 during cooking. In addition, controller 1000 of cooker 10 monitors the measurements of the weight made by the load cells 30 during use, and alters/regulates the behaviour of the heating component in response to the measurements made.

[148] In advance of operating the core function of monitoring the weight changes and regulating the behaviour of the heating component, the controller 1000 is also programmed to initiate the setup sequence needed to use the reduction by weight mode. Once the user has selected the reduction by weight mode using dial 900, display 15 and buttons 14, controller 1000 follows a prescribed sequence of steps to configure the cooker 10 for a reduction of a foodstuff by weight. During this process the controller may offer prompts to the user via the display 15 to complete the setup process, and the user may interact with such prompts via dial 900 and buttons 14. Fig. 8 shows a flow diagram of the operation of controller 1000 during the reduction by weight mode. The process is initiated in the mode selection at step S1.

[149] During step S2 of Fig. 8, the reduction by weight mode is setup and the criterion for controller 1000 to monitor established. This process is described in further detail below.

[150] During setup for reduction by weight cooking, the user places a container on the cooker 10. Upon activation of the reduction by weight mode, or after a user prompt, the controller 1000 takes an initial measurement from the load cells 30 to determine the weight of the empty container and stores the measurement in memory on board or associated with controller 1000. The measurement of the empty container may be taken either after an elapsed time, or via a user prompt, or by the controller 1000 recognising a change in the load measured by the load cells 30 that indicates the container has been placed on the cooker 10. However obtained, the measurement of the empty container may later be subtracted from the measurements made by the load cells to provide measurements of the foodstuffs (such process is commonly known as ‘taring’).

[151] Subsequently, the user adds the foodstuff to be reduced to the container, increasing the weight measured by the load cells 30 and thereby arrives at the arrangement shown in Fig. 7. Controller 1000 then takes a second measurement, either after an elapsed time, or via a user prompt, or by the controller recognising a change in the load measured by the load cells 30 as a result of placement of foodstuff in the container. After the measurement of the initial weight of the container with the foodstuff is made, the associated measurement is stored in the memory attached to controller 1000. From the difference of the two measurements stored in the memory, the initial weight of the foodstuff that has been added to the container is calculated and is also stored in memory, meaning that three values are stored in memory: the weight of the empty container; the total weight of the container and the foodstuff; and the initial weight of the foodstuff.

[152] The user is then requested to specify or select from a series of options reduction that is to be achieved using the dial 900, buttons 14 and display 15. In one example, the reduction may be based upon a threshold or range, such as ‘reduction until there is 100g of foodstuff left’, or ‘reduction until there is between 150g-250g of foodstuff left’. Once a reduction has been specified or selected, a target reduction weight is calculated by the controller 1000, which forms the criterion examined by the controller 1000 that provides the indication that the reduction by weight process is complete.

[153] In the above example of a ‘reduction until there is 100g of foodstuff left’, the controller 1000 requires that the target reduction weight is equal to the weight of the empty container plus 100g. In these scenarios, the previously calculated weight of the initial foodstuff is not needed for the calculation of the target. However, controller 1000 performs an error check to ensure that the target reduction weight does not exceed the total weight of the container and the foodstuff. If an error is present, the user is notified via display 15 and asked to re-specify or re-select a target reduction weight.

[154] As an alternative, the user may specify or select from a series of options a specified amount to reduce, such as ‘reduce until 50% of the initial foodstuff is left’. In these scenarios, the controller 1000 takes the stored value of initial weight of the foodstuff calculated previously and determines the required change in the weight that is needed to achieve the target reduction weight. The target reduction weight is comprised of the weight of the empty container plus (50% x the initial weight of the foodstuff). Controller 1000 may initiate a warning to the user if the reduction is too great (for example if the specified amount to reduce is ‘reduce until 10% of the foodstuff is left’) and a risk of burning the foodstuff to the container exists.

[155] Further alternatively, the user may specify or select a target difference in the measured parameter, such ‘reduce foodstuff by 100g’. In such a scenario, since only the relative difference in the measured parameter is being monitored here, the target reduction weight is calculated based on the total weight and the change required. For example, a ‘reduce foodstuff by 100g’ requires that the target reduction weight is the total weight of the container and the foodstuff minus 100g.

[156] When making the above selections for targets, the user either selects one of a series of options from among a series of factory pre-sets, or sets the value themselves using the dial 900, optionally using the dial 900 to increment or decrement a counter on the display and confirming the selection with buttons 14. For example, the display 15 may read “Reduction

and the user turns the dial 900 to provide a number to insert into the blank space. If the user makes an erroneous selection or specification, for example, a reduction by weight of 200g when only 150g of foodstuff is present in the container, the user receives an error warning, and may be asked to re-select or re-specify a target reduction parameter. Alternatively, the reduction by weight mode may be exited.

[157] Once a target reduction weight has been established by the controller 1000 on the basis of the user’s specification or selection, the set up process is complete. At this point, the user may initiate (possibly via a prompt from display 15) the heating that will be caused by the heating component.

[158] In operation and once the heating component has been activated, the controller 1000 periodically pings or is automatically provided with a measurement of the weight from each of the load cells 30, for example, every 5s. Alternative intervals between measurements are also possible. Additionally, instead of direct measurements of the weight from the load cells 30 as in the present example, different parameters that are a function of the mass or weight may be measured (possibly from different sensors, e.g. an evaporation sensor), since these parameters will vary linearly with the changes in weight of the foodstuff within the container during the reduction. [159] Upon receipt of the measurement signal from the load cells 30, the controller 1000 interrogates the signal and compares the signal to the criterion established during setup to see if the target reduction weight criterion has been met. This reception, comparison and determination process is illustrated in Fig. 8, steps S3, S4 and S5. If the criterion has not been met, the controller 1000 takes the “NO” path in Fig. 8 and continues to monitor the measurements provided by the load cells 30. In such an instance, steps S3, S4 and S5 repeat each time the measurement is received, but controller 1000 does not otherwise affect the heating process.

[160] If the criterion has been met, the controller 1000 proceeds down the “YES” branch after step S5 to step S6. The heating caused by the heating component is altered, in this example by reducing the amount of heating caused. Reducing the heating reduces the rate of evaporation from the foodstuff, leaving the foodstuff either to simmer on a low heat, where evaporation is minimal, or alternatively, the heating is deactivated and the foodstuff is allowed to cool to ambient temperature.

[161] Cooker 10 further provides an alert, either audibly or visually, which indicates to a user (who may be occupied elsewhere) that the required reduction is complete. Nevertheless, the controller 1000 alters the heating caused by the heating component without user intervention.

[162] Although in the embodiment, all load cells 30 are pinged to take a measurement or each automatically provides a measurement, in some instances, only a subset of the load cells 30 needs be pinged.

[163] Additionally, or alternatively, whilst load cells 30 are used to directly measure the changes of in the weight of the foodstuff being reduced using the method described above, alternative sensors would be possible that may measure the amount of evaporation from the foodstuff, thereby indirectly providing an indication of the change in weight of the foodstuff in the container.

[164] An alternative and simpler (albeit less flexible) form of the reduction by weight mode operates only a single type of reduction (e.g. ‘reduce foodstuff by 50g’) and this criterion may be established without interaction with the user in step S2. Instead, the criterion, and corresponding target reduction weight may be pre-programmed, and establishment of the criterion is automatic upon entry into the reduction by weight mode.

[165] Although described in the context of an induction cooker, the reduction by weight mode may be implemented in other types of cooker. Consequently, there is provided a cooker for use with a container for a foodstuff, the cooker comprising a heating component configured, in use, to cause heating of the foodstuff disposed in the container, a sensor configured to measure a parameter of the foodstuff during heating, wherein the parameter is a function of the weight of the foodstuff disposed in the container; and a controller connected to the sensor and to the heating component, wherein the controller is configured to monitor the parameter and to alter the heating caused by the heating component in response to a change in the value of the parameter. Similar to the previously described induction cooker, such a general cooker is able to respond to automatically alter the heating of the foodstuff in response to a change in a parameter related to the weight of a foodstuff. The manner of operation and the optional features of this cooker may be implemented in the same fashion as those for the induction cooker previously described.

Temperature sensor and circulator tool system

[166] The temperature sensor 700 and circulator 600 previously described (both examples of external components and of tools) form part of a tool system 2000. Tool system 2000 provides a predictable and reproducible separation between the impeller of the circulator 600 and the thermocouple of temperature sensor 700, such that each time the tool system 2000 is assembled and the separation between these elements is established (and maintained), the relative distance between the elements is the same, and is determined by a separation means. Since the separation between these tools is the same, the user may reliably achieve a high accuracy of temperature measurement of the liquid or fluid foodstuff, whilst that liquid or fluid foodstuff is being influenced (i.e. made to flow) by the impeller of the circulator 600. However, advantageously, the user retains the flexibility to assemble and disassemble the tool system 2000 between uses because each tool (in this case the circulator 600 and the temperature sensor 700) is removably attachable from one another. The user is not forced to have a single integrated unit comprising each of the circulator 600 and the temperature sensor 700 to achieve high accuracy of the temperature measurements.

[167] One context in which the accurate reproducible separation between the thermocouple and the impeller provides an advantage is for sous vide cooking. Sous vide is a method of cooking in which the foodstuff is placed in a sealed container/pouch and placed in a bath of liquid or fluid foodstuff at a regulated temperature. Sous vide cooking is characterized by its low, precisely regulated temperature and longer cooking times, and by the use of a further container/pouch (such as a plastic bag). The further container separates the foodstuff from its heating environment, and provides a pressurized enclosure using full or partial vacuum. In sous vide cooking, precise control of the temperature is critical for the cooking end results, and therefor accurate temperature readings are important. Further, the reproducibility of the cooking results is reliant on being able to consistently produce a desired temperature, which is itself reliant on producing highly accurate temperature measurements. The tool system 2000 is an example of a system that advantageously enables the user to consistently produce accurate temperature measurements.

[168] Fig. 9 shows the tool system 2000 in a disassembled state, which includes circulator 600 and temperature sensor 700 and the assembled state of tool system 2000 is shown in Fig. 8. In this example of a tool system 2000, the separation means includes clip 652 attached to circulator 600, and temperature sensor 700 is removably attachable to the circulator 600 to form tool system 2000. Once assembled, the frictional engagement provided by clip 652 maintains the separation between the temperature sensor 700 and circulator 600 that has been established, until the later point at which the user disassembles the tool system 2000.

[169] Clip 652, which is integral to circulator 600 as previously described, is an example of an element of a separation means that enables tool system 2000 to achieve its advantages. On assembly, clip 652 frictionally engages the temperature sensor 700, via main body 706, to releasably hold the temperature sensor 700 in place. The temperature sensor 700 is released and the tool system 2000 disassembled by a user overcoming the frictional hold of the clip 652 on main body 706. Whilst the connection between the circulator and temperature sensor is clip 652 in the present instance, alternative connections would be possible, such as a magnetic connection, a hook and loop fastening or a thermally resistance adhesive.

[170] On assembly into the configuration shown in Fig. 10, clip 652 contributes to setting the relative distance between the thermocouple and the impeller. Clip 652 is oriented to receive temperature sensor 700 such that the main body 706 of the temperature sensor 700 is disposed parallel to the circulator 600 and is aligned with the circulator 600. This is achieved by setting the location of the attachment between the circulator 600 and the temperature sensor 700. The shape and size of clip 652 determines the relative distance between the main body 706 of the temperature sensor 700 and the lower section 602b of the circulator 600, because main body 706 of temperature sensor 700 is prevented by the ‘bulk’ of clip 652 from being closer to the circulator 600, and would not be connected by the jaws of clip 652 if further away. Thus a specified separation between the main body 706 and the lower section 602b is set and maintained by the clip 652.

[171] In conjunction with clip 652, the separation means also includes recess or indent 654 which is adapted to receive the bent end portion 704 of temperature sensor 700. Since temperature sensor 700 includes end portion 704 at an angle to its elongated main body 706 as shown in Fig. 9, the orientation of the temperature sensor 700 is fixable relative to the circulator 600. The ‘correct’ orientation results in end portion 704 being disposed in indent 654. The indent 654 therefore assists in the reproducible configuration of tool system 2000 on assembly and ensures that the temperature sensor 700 and the circulator 600 have the same relative orientation each time the tools are assembled into the tool system 2000. Setting the temperature sensor 700 in the ‘correct’ orientation ultimately sets the orientation of the thermocouple with respect to the circulator’s impeller.

[172] Additionally, the combination of the extent of the end portion 704 of temperature sensor 700, the relative locations of clip 652 and indent 654 collectively ensures that clip 652 consistently attaches to the same portion of main body 706 during each use (rather than to different portions along the main body’s length), thereby achieving a consistent location of attachment. The consistent location of attachment between main body 706 and clip 652 ensures that the thermocouple in the probe point and impeller are always the same relative distance apart, each time the tools are assembled into the tool system 2000.

[173] Whilst the above combination forms a specific example of a separation means, more generally, the two set contact points (the clip 652 and indent 654) between the two tools (temperature sensor 700 and the circulator 600) ensure that the separation is the same of the two tools each time that the tool system is assembled. Coupled further with the shape of a tool that means the two contact points are not collinear with the direction of extension of the tool (such as the bent portion 704 that does not extend co-linearly with the main-body portion 706), the relative orientation of the two tools in the tool system is set on assembly.

[174] Whilst the indent 654 assists in the setting and maintaining the orientation of the temperature sensor, in the present example, indent 654 does not actively support or secure the end portion 704 of the temperature sensor 700 in the indent 654. Rather, the indent 654 provides a guide for the user to ensure the consistent orientation of the temperature sensor 700 (and thereby the thermocouple). The primary support and securing of the temperature sensor 700 to the circulator 600 is achieved by clip 652. In alternative configurations, indent 654 may be replaced with a further means of attachment to provide further support to secure temperature sensor 700, such as second clip, a magnetic interface or a hook and loop fastening.

[175] In use, through the cooperation of clip 652 and indent 654, the thermocouple of temperature sensor 700 is consistently disposed in close proximity to the impeller housed within lower section 602b and to inlet apertures 612 and outlet apertures 614. Close proximity between the impeller and the thermocouple of the temperature sensor 700 ensures that an accurate measurement of the temperature of the liquid or fluid foodstuff that is being circulated is made, and the user is not required to rely on an indirect measurement from (for example) temperature sensor 12, which contacts the base of the container, rather than the liquid or fluid foodstuff.

[176] By ‘close proximity’ is meant within 100mm, generally less than or equal to 50mm and preferably, less than equal to 20mm. Further, the thermocouple is not only a short distance from the impeller, but is also positioned in the same relative position with respect to the impeller, the inlet apertures 612 and the outlet apertures 614. This ensures that the thermocouple of the temperature sensor 700 adopts the same relative position in the circulating flow each time it is used, resulting in consistent conditions that aid the reliability of the temperature measurements, even when the tool system 2000 is used on different occasions. The close proximity of the temperature sensor 700 and circulator 600 provides a further advantage of minimising the interference of the tools in the tool system 2000 with the remainder of the foodstuffs in the pan, because the tools occupy the minimum of space.

[177] As shown in Fig. 11 , a further element of the separation means is the attachment means 604 previously described in connection with the circulator 600. The clip 606 (as an example of attachment means 604) attaches the tool system 2000 in a specific geometric relationship between the container and the tool system 2000. The attachment is achieved in the same manner that the attachment means 604 attaches the circulator 600, when the circulator 600 is used alone, and a user is not required to operate a different type of attachment for the tool system 2000 and the circulator 600.

[178] In conjunction with clip 652, the attachment means 604 ensures secure placement of both the temperature sensor 700 and circulator 600 (assembled as tool system 2000) with a single attachment point and advantageously avoids the need for a separate attachment to fix the temperature sensor 700 in place. Once attached, the tool system 2000 and container may be moved as a single unit.

[179] Attachment means 604 provides a further specific relationship between the orientation and the location of the tools in tool system 2000 and the container. The attachment means 604 and thereby further improves the accuracy of the sensing by ensuring a fixed distance also exists between the base of the container and/or the rim of the container and the tools of the tool system 2000. Hence, the thermocouple of the temperature sensor 700 sits in the same position in the flow of liquid or fluid foodstuff, not only with respect to the impeller of circulator 600, but also with respect to the rim/side/base of the container. The ensuing temperature measurement is therefore made using a thermocouple that also adopts the same relative position with respect to the container each use, thereby increasing the consistency of the conditions experienced by the temperature sensor 700 each use because the effect of the side of the container on the flow of the liquid or fluid foodstuff is also reproducible.

[180] In addition to the thermocouple orienting function of indent 654, indent 654 also provides a cable-tidying function by setting the ‘correct’ orientation of end portion 704. As previously described, the cabling of the temperature sensor 700 attaches to the end of bent end portion 704, opposite the bend that sits in indent 654. Hence, the direction that the end portion 704 points towards also the direction that the cabling points. As shown in Figs 10 and 11 , since end portion 704 is directed by indent 654 to point towards the clip 606, the cabling of the temperature sensor is directed away from the centre of the container in a direction generally parallel to the cabling for circulator 600 (the circulator cabling being directed by cable tidying means 630). Thus indent 654 and cable tidying means 630 both assist in ensuring that the cabling of tool system 2000 does not stretch towards the centre or the container.

[181] Whilst in the present example, clip 652 and indent 654 act as the separation, other separation means may be implemented, such as a multiple clip or a pin and socket arrangement. Further, in principle, a different the separation means may be ‘settable’ or adjustable such that separation means always determines the relative distance between the first tool and the second tool, but the user may configure what that relative distance is to be.

[182] Whilst applied in the above description to the temperature sensor 700 and circulator 600 in the present instance, the principles of the tool system 2000 may be equally applied to other tools, such as a boil-over sensor 200

Container analysis

[183] The heating component of the induction cooker is the induction coil. During operation, a container is placed on the upper surface of cooker 10 in fashion similar to that shown in Fig. 11. A high-frequency, high-current (pulsed) drive signal is applied to the induction coil. The container on the upper surface stands in the oscillating magnetic field that exists when the signal is run through the coil. The drive signal induces eddy currents inside the container according to Faraday’s law and once induced in the container, the eddy currents heat the container via Joule heating. The heat generated in the container passes from the container to the foodstuff contained therein. In addition, in ferromagnetic containers, when the magnetic field that is applied to the ferromagnetic material is increased and then decreased, prompted by the variation in the drive signal, the resulting field within the material fails to return to its original level in a corresponding manner. Hysteresis losses from the realigning magnetic domains occur and result in the further generation of heat in the container, which also passes from the container to the foodstuff contained therein.

[184] Electronically, the induction coil and the container can be considered as a transformer, in which container acts as shorted secondary load providing a resistance. The coil and container of an induction cooker are together typically configured as resonant RLC circuit. The container forms the resistance of the inductive coil of the cooker, thereby acting as the secondary load. If the container is ferromagnetic, the container forms a magnetic core to the inductive coil too. The circuit is typically powered by either a quasi-resonant power stage or a half-bridge resonant circuit, and for effective and efficient operation, the resonant frequency of the cooker-container circuit is found.

[185] Not all containers are equally suitable for induction cooking. Whilst any conductive container may provide eddy currents, typically containers for induction cookers are made from ferromagnetic materials. Such a construction enables the container to act as a magnetic core and thereby facilitate hysteresis losses to provide an additional source of heating. Particularly suitable materials for the containers include stainless steel, or cast iron, which have high relative permeability. The high relative permeability also leads to reduced skin depth and high surface resistance, thereby assisting in effective heat transfer to the foodstuff. Additionally, in general, the geometry of the container preferably incorporates a flat base, since the magnetic field arising from the drive signal reduces with distance from the induction coil.

[186] Cooker 10 includes a ‘container analysis’ or ‘pan analysis’ mode during which the user is provided with an indication as to the suitability of a given container disposed on the upper surface of the cooker 10 for use in induction cooking. The container analysis evaluates the suitability of the container for the cooker 10 by providing a characterisation of the cooker-container system. Since the same cooker 10 is used with each particular container, the characterisation is effectively of the container and the container analysis advantageously provides the user with feedback information on how the container responds to the drive signal. This permits a user to assess the suitability of a container for use with cooker 10, even if the user does not otherwise have any indication of whether the container may be effectively used with the induction cooker (for example, the original packaging for the container is no longer available) and the container is not suitably marked. In other contexts, a user may have an old container that was assessed to be particularly suitable for induction cooking, but which is now otherwise unavailable. The user may assess the effectiveness of any replacement container by assessing the suitability of the container for induction cooking using the container analysis mode of cooker 10. In response to the indication provided by the analysis, the user can recognise whether or not the replacement container is suitable, and might thereby reproduce the cooking conditions achieved using the old container, or not. Such an indication therefore aids in the reproducibility of cooking conditions, and ultimately in the reproducibility of cooking end results.

[187] In order to analyse a container, a scheme as generally outlined in Fig. 13 is followed. The user places the container on the upper surface and uses the dial 900, one or more buttons 14 and display 15 to select the ‘container analysis’ mode S10. In some instances the container is filled with a reference material or foodstuff, for example 200ml of water, to be heated. The material or foodstuff acts as a heatsink, thereby avoiding the container overheating.

[188] Once selected, the controller 1000 initiates a sequence of steps to sweep through a series of frequencies S20 to stimulate a response from the container. The controller 1000 monitors the container’s response S30 and then identifies a resonance peak S40. Once the peak has been identified, the characteristic of the container is derived S50 and finally an indication of the suitability of the container is output to the user S60.

[189] The controller initiates a sweep through a range of frequencies in order to determine the resonant frequency. In some instances the frequency is used to set the timing of the gate driver that is driving the switching element used to provide the drive signal. The range of frequencies ‘swept through’ is typically between 10kHz and 100kHz, and in some instances is between 18kHz to 30kHz.

[190] Cooker 10 includes a resonant frequency feedback circuit, the feedback of which is monitored by controller 1000. In one example, the feedback circuit is a voltage comparator circuit. The comparator circuit may generate an output signal based at least in part on the drive signal (a voltage) and a signal (a voltage) measured across a collector-emitter junction that is indicative of the container’s response.

[191] In response to the measurements from the feedback circuit, the controller 1000 is configured to identify (S40) the frequency of the resonance peak of the cooker-container circuit. In instances where the sweep uncovers multiple resonance peaks, the controller 1000 is configured to differentiate between them on the basis of the Q factor of each peak, with the highest Q factor peak is selected as the representative peak of the container, which is typically the fundamental resonant frequency. In other instances, a different selection criterion (e.g. closest to 20kHz), or a different basis for differentiation between the peaks (e.g. bandwidth), may be applied by controller 1000 to choose the resonance peak. [192] If no resonance peak is determined, the controller 1000 may issue an error indication and exit the container analysis mode. Additionally, or alternatively, an audible or visible alert may be provided to the user of the error condition.

[193] Once the peak has been identified by controller 1000, one or more of parameters of the resonance peak, such as an applied amplitude, phase or frequency of the drive signal or the bandwidth, amplitude or Q-factor of the resonance peak is determined, and a characteristic of the cooker-container circuit derived (S50) from the determined parameter. Alternatively, from the feedback circuit’s response at the resonance peak, the controller 1000 may infer a parameter of the container such as the surface resistance, magnetic permeability or the electrical conductivity of the container, and then derive a characteristic (S50) from that determined parameter. In either case, a derived characteristic of the container is obtained that represents the response at resonance of the container in the cooker-container circuit.

[194] From the derived characteristic, the suitability of a container for induction cooking can be inferred because the cooker has the same properties in each instance. For example, if the derived characteristic is (or is a function of) the magnetic permeability and the container is nonferromagnetic, a low magnetic permeability will be evident from the derived characteristic and a low suitability of that container for induction cooking would later be indicated.

[195] Once the characteristic of the cooker-container circuit has been determined, an indication of the suitability of the container for use with cooker 10 (step S60) is provided to the user by display 15. The indication may be a display of the derived characteristic that has been derived, or a function thereof. Alternatively a phrase may be displayed, based on the derived characteristic, and is representative of the container’s ability to generate heat for cooking when used with the induction cooker. In one example, the correspondence between a characteristic and the indication is provided in a database or lookup table stored on memory associated with the controller 1000.

[196] In some instances, the display 15 may provide an alternative or further parameter indicating the suitability of the container that is a dimensionless number, for example a number between 1 and 10, where 10 indicates high suitability and 1 poor suitability for induction cooking on cooker 10. In some instances, the dimensionless number is accompanied by an audible or visible alert or message that interprets the meaning of the dimensionless number for novice users. Continuing the above example of a non-ferromagnetic container, display 15 may show the phrase “3 - warning: container has poor suitability for induction cooking”, or similar. [197] Providing the user with an indication of the suitability of the container assists the user in selecting a high suitability container because the user is informed when an unsuitable container is present. Using a high suitability container leads to the most efficient heating, where efficiency is determined by the ratio of the energy supplied by the induction coil relative to the heat applied to the foodstuff. Efficient heating both reduces the energy consumption of cooker 10 because the cooker need not be powered-on for as long, and preserves the internal circuitry of the induction coil and the cooker 10 more generally, leading to a longer circuit lifetime.

[198] In addition to providing an output indication to the user, the controller 1000, based on the resonance peak identified, sets a specific frequency or range of frequencies for the driving pulse, and adjusts the drive circuit to provide the most efficient heating for the specific container.

[199] In some instances, the induction cooker comprises a memory that is configured to store a container profile. A container profile provides an identifier for the container and an indication of the suitability of that container for induction cooking. The container profile may also store a record of the resonant frequency of the cooker-container circuit, and the derived characteristic or a function thereof. This profile may be stored in memory and recalled therefrom by the user interfacing with buttons 14, dial 900 and display 15 to give commands to controller 1000. In addition, the container profile may provide further information, for example the weight of the container as read by load cells 30, or date information regarding the first use of the container to provide a record of the age of the container, or a record of the number of uses. Storing one or more container profile(s) means that the user need not repeat the container analysis process each time the user wishes to use the container on the cooker 10. In alternative instances, the controller always records the output indication whenever the container analysis mode is completed. The record may assist in the maintenance of the induction cooker by providing a record of the containers that have been used for cooking.

[200] In some further instances, the cooker 10 contains a communication port compatible with a removable storage medium, (e.g. a ‘USB stick’ or ‘flashdrive’, or other similar type of memory), or a wireless or wired interface, that permits container profiles to be transferred to or from the induction cooker from another location. Such an operation may also be controlled using buttons 14, display 15 and dial 900. Transferring the profile to the cooker 10 avoids the need to use the container analysis mode to derive the information needed to use the container. Transferring the container profile from permits the profile to be used in other cookers. Once transferred to the cooker 10, the transferred profiles may be recalled from the memory by controller 1000 in the same manner as stored profiles that have been made ‘locally’ by the cooker 10. [201] It will be appreciated that the above disclosure provides specific examples of certain implementations of the invention, and that modifications can be made within the scope of the appendant claims

Claims

47 CLAIMS

1. An induction cooker for use with a container for a foodstuff, the induction cooker comprising: a heating component configured, in use, to cause heating of the foodstuff disposed in the container; a sensor configured to measure a parameter of the foodstuff during heating, wherein the parameter is a function of the mass or the weight of the foodstuff disposed in the container; and a controller connected to the sensor and to the heating component, wherein the controller is configured to monitor the parameter and to alter the heating caused by the heating component in response to a change in the value of the parameter.

2. The induction cooker of claim 1 , wherein the controller is configured to alter the heating when the value of the parameter is equal to or passes a threshold value.

3. The induction cooker of claim 1 or claim 2, wherein the controller is configured to alter the heating when the value of the parameter enters or exits a range.

4. The induction cooker of one of claims 1 to 3, wherein the controller is configured to monitor the parameter for a specified change in the value of the parameter and to alter the heating when the specified change in the value of the parameter has occurred.

5. The induction cooker of claim 4, wherein the specified change is a percentage change, and optionally, wherein the percentage change is ±30%.

6. The induction cooker of one of claims 1 to 5, wherein the parameter is the mass or the weight of the foodstuff disposed in the container.

7. The induction cooker of one of claims 1 to 6, wherein the sensor comprises a load cell and optionally, wherein the induction cooker has one or more feet and the load cell is disposed in the one or more feet.

8. The induction cooker of one of claims 1 to 7, wherein the alteration of the heating caused by the heating component is a reduction in the heating caused by the heating component, and optionally, wherein the alteration of the heating caused by the heating component is a deactivation of the heating caused by the heating component.

9. The induction cooker of one of claims 1 to 8, further comprising an audible or visual alarm to indicate the change in value of the parameter.

10. The induction cooker of claim 2 or any claim dependent on claim 2, wherein the induction cooker further comprises means configured to enable the user to set the threshold value.

11. The induction cooker of claim 3 or any claim dependent on claim 3, wherein the induction cooker further comprises means configured to enable the user to set the range. 48

12. The induction cooker of claim 4 or any claim dependent on claim 4, wherein the induction cooker further comprises means configured to enable the user to set the change in the value of the parameter.

13. A tool system for use with an induction cooker, wherein the induction cooker comprises a container for a liquid or fluid foodstuff, the tool system comprising: a first tool for sensing a property of the liquid or fluid foodstuff; a second tool for influencing a property of the liquid or fluid foodstuff; and separation means configured to determine the relative distance between the first tool and the second tool when each of the first tool and the second tool is disposed in the liquid or fluid foodstuff, wherein at least one of the first tool and the second tool is configured to be removably attached to the separation means and/or to the other of the first tool and the second tool.

14. The tool system of claim 13, wherein the separation means is further configured to provide the removable attachment between the first tool and the second tool.

15. The tool system of claim 13 or claim 14, wherein the separation means is integral with either the first tool or the second tool.

16. The tool system of claim 14 or claim 15 when dependent on claim 14, wherein the separation means comprises a clip to provide frictional or pinching attachment between the first tool and the second tool, and optionally, wherein the clip is made from silicon.

17. The tool system of one of claims 14 to 16, wherein the separation means is further configured to determine the orientation of the first tool or the second tool when that tool is attached to the separation means.

18. The tool system of claim 17, wherein either: the separation means further comprises an orienting recess located on the first tool and configured to cooperate with a portion of the second tool in order to set and maintain the orientation of the second tool relative to the first tool; or the separation means further comprises an orienting recess located on the second tool and configured to cooperate with a portion of the first tool in order to set and maintain the orientation of the first tool relative to the second tool;

19. The tool system of one of claims 14 to 18, wherein the separation means is further configured to determine the location of the removable attachment of the first tool or the second tool to the separation means.

20. The tool system of claim 19, wherein either: the separation means further comprises a locating recess located on the first tool and configured to cooperate with a portion of the second tool in order to set and maintain the location of the removable attachment between the second tool and the first tool; or 49 the separation means further comprises a locating recess located on the second tool and configured to cooperate with a portion of the first tool in order to set and maintain the location of the removable attachment between the first tool and the second tool.

21. The tool system of claim 19 when dependent on claim 17 or on claim 18, or the tool system of claim 20 when dependent on claim 17 or on claim 18, wherein the orienting recess and the locating recess are the same recess.

22. The tool system of one of claims 13 to 21 , wherein the first tool comprises a sensing element and the second tool comprises an influencing element, and wherein the relative distance between the sensing element and the influencing element is less than or equal to 50mm and optionally, less than equal to 20mm.

23. The tool system of one of claims 13 to 22 further comprising attachment means for removably attaching the tool system to the container.

24. The tool system of claim 23, wherein the container has a rim and a base and the attachment means is configured to attach the tool system to the container such that: a fixed distance exists, in use, between the base of the container and the first tool or the second tool when each of the first tool and the second tool are disposed in the liquid or fluid foodstuff; or a fixed distance exists, in use, between the rim of the container and the first tool or the second tool when each of the first tool and the second tool are disposed in the liquid or fluid foodstuff; or both.

25. The tool system of claim 23 or claim 24, wherein the attachment means is further configured to determine the orientation of the tool system with respect to the container.

26. The tool system of one of claims 23 to 25, wherein the attachment means comprises a clip, and optionally, a biased clip.

27. The tool system of claim 26, wherein the container comprises a side, and the clip comprises a protruding foot configured to secure the clip arm to the side.

28. The tool system of one of claims 13 to 27, wherein at least one of the first tool and the second tool comprises cabling, and at least one of the first tool, the second tool and the separation means comprises cable tidying means to receive a portion of the cabling.

29. The tool system of claim 28 wherein at least one of the first tool or the second tool comprises cabling, and the cable tidying means is disposed on the one of the first tool or the second tool.

30. The tool system of claim 28 when dependent on one of claims 23 to 27, or of claim 29 when dependent on one of claims 23 to 27, wherein the cable tidying means directs the cabling towards the attachment means. 50

31. The tool system of one of claims 13 to 30, wherein the first tool comprises a temperature sensor and the sensed property is the temperature of the liquid or fluid foodstuff, or wherein the second tool comprises a circulator and the influenced property is the flow of the liquid or fluid foodstuff, or both.

32. The tool system of one of claims 13 to 31 , wherein one of the first tool and the second tool comprises a visible depth marker to indicate, in use, the extent of submersion of the tool in the liquid or fluid foodstuff.

33. An induction cooker or a kit of parts comprising the tool system of one of claims 13 to 32.

34. An induction cooker comprising the kit of parts of claim 33, wherein induction cooker comprises a housing and wherein the housing is configured to store part or all of the kit of parts when the kit is not in use.

35. An induction cooker for use with a container for a foodstuff, the induction cooker comprising: a circuit configured, in use, to: apply a signal to the container; monitor a response to the signal; and derive a characteristic of the container based upon the response; wherein the induction cooker further comprises an output means configured to output, to the user, an indication related to the derived characteristic.

36. The induction cooker of claim 35, wherein the signal comprises a drive signal having a drive frequency, and wherein the circuit is further configured to: sweep the drive frequency through a range of frequencies from below a resonance of the container to above a resonance of the container; and wherein the characteristic of the container is based upon the monitored response at the resonance.

37. The induction cooker of claim 36, wherein the circuit is further configured to determine one or more of: an amplitude, phase or frequency of the drive signal at the resonance; a bandwidth of the resonance; an amplitude of the resonance; a Q-factor of the resonance; or a function of one or more of these parameters.

38. The induction cooker of one of claims 35 to 37, wherein the circuit is further configured to determine the magnetic permeability, or the surface resistance, or the electrical conductivity of the container, or a function of one or more of these parameters, wherein the characteristic of the container is a function of the determined parameter(s).

39. The induction cooker of one of claims 35 to 38, wherein the output means is a visual display.

40. The induction cooker of one of claims 35 to 39, further comprising a memory, wherein the memory is configured to store a container profile, wherein the container profile associates the container with the indication of the characteristic of the container.

41. The induction cooker of claim 40, wherein the induction cooker is further configured to upload or download the container profile from a removable storage medium, or from a wired or wireless network.

42. The induction cooker of claim 40 or claim 41 , further comprising recall means configured to recall a stored container profile.

43. The induction cooker of one of claims 35 to 42, wherein the circuit is further configured to adjust the electromagnetic induction to be produced by the induction cooker in response to the characteristic of the container.

44. A method of providing a user an indication of a characteristic of a container for a foodstuff for use with an induction cooker, the method comprising the steps of: applying a signal to the container; monitoring a response to the signal; deriving a characteristic of the container based upon the response; and outputting the indication of the derived characteristic to the user.

45. The method of claim 44, wherein the signal comprises a drive signal having a drive frequency, and further comprising the step of: sweeping the drive frequency through a range of frequencies from below a resonance of the container to above a resonance of the container; and wherein the characteristic of the container is based upon the monitored response at the resonance.

46. The method of claim 45, further comprising the step of determining one or more of: an amplitude, phase or frequency of the drive signal at the resonance; a bandwidth of the resonance; an amplitude of the resonance; a Q-factor of the resonance; or a function of one or more of these parameters.

47. The method of one of claims 44 to 46, further comprising the step of determining the magnetic permeability, or the surface resistance, or the electrical conductivity of the container, or a function of one or more of these parameters, wherein the characteristic of the container is a function of the determined parameter(s).

48. The induction cooker of one of claims 35 to 43 or the method of one of claims 44 to 47, wherein the indication comprises a parameter indicating the suitability of the container for use with the induction cooker, and optionally, wherein the parameter is a dimensionless number.

49. The induction cooker of claim 48 or the method of claim 48, wherein the parameter indicating the suitability of the container for use with the induction cooker is displayed alongside a message indicating to the user to the suitability of the container.

50. The method of one of claims 44 to 49, wherein the outputting of the indication of the derived characteristic is provided on a visual display.

51. The method of one of claims 44 to 50, further comprising the step of storing a container profile, wherein the container profile associates the container with the indication of the characteristic of the container.

52. The method of claim 51 , further comprising the step of uploading or downloading the container profile from a removable storage medium, or from a wired or wireless network.

53. The method of claim 51 or claim 52, further comprising the step of recalling a stored container profile.

54. The method of one of claims 44 to 53, further comprising the step of adjusting the electromagnetic induction to be produced by the induction cooker in response to the characteristic of the container.

55. The method of one of claims 44 to 54, wherein a step of the method is executed by a circuit and optionally, wherein each step of the method is executed by the circuit.

56. An induction cooker comprising a combination of features of the induction cooker of one of claims 33 or 34 and either or both of: the induction cooker of one of claims 1 to 12; and the induction cooker of one of claims 35 to 43.

57. An induction cooker comprising a combination of features of the induction cooker of one of claims 1 to 12 and the induction cooker of one of claims 35 to 43, and optionally, further comprising the tool system of one of claims 13 to 32.

58. A kit of parts comprising: a container for a foodstuff for use with an induction cooker; and the induction cooker of claim 33, or of one of claims 1 to 12 or one of claims 35 to 43, or of claim 56 or of claim 57.