AU2015275269B2

AU2015275269B2 - Toaster with temperature control

Info

Publication number: AU2015275269B2
Application number: AU2015275269A
Authority: AU
Inventors: Denan Diep; Maxim Guyatt; Alex Tofaili
Original assignee: Newell Australia Pty Ltd
Current assignee: Newell Australia Pty Ltd
Priority date: 2014-12-23
Filing date: 2015-12-22
Publication date: 2020-02-27
Anticipated expiration: 2035-12-22
Also published as: AU2015275269A1; CN105708351A

Abstract

A toaster comprising a body having at least one opening into a toasting slot, a carriage located within the toasting slot for holding a food item to be toasted and movable between a raised position and a lowered position, a plurality of heating elements located 5 within the body for toasting the food item when in the lowered position, at least one temperature sensor for sensing the temperature within the toasting slot, a user interface for enabling a food-type selection of one of at least two different food items, and a controller for controlling the operation of the toaster. The controller is responsive to the food-type selection at the user interface and to the sensed temperature, and is 10 configured to determine an end temperature associated with the food item being in a toasted state, the calculated end temperature being dependent on an initial sensed temperature, wherein the controller is arranged to de-energise the heating elements in response to the sensed temperature reaching the determined end temperature. IA4-h pI6- 2

Description

Toaster with temperature control

Field of the invention

The present disclosure relates to a toaster for toasting foodstuff, and in particular to a toaster having a temperature measurement.

Background of the invention

Toasters are well-known kitchen appliances used for toasting foodstuff, typically slices of bread or other bakery products which are heated until the outer surface of the products has a yellow, golden or brown colour.

Different amounts of heating are needed depending on the type of bread that is placed in the toaster. In conventional toasters the user has to adjust the toasting cycle to achieve the desired level of toasting. Commonly, this is done by varying a timer, or by initiating multiple toasting cycles. However, this is often done by guesswork and toast is frequently underdone or burnt.

Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

Summary of the invention

According to a first aspect of the invention there is provided a toaster comprising:

a body having at least one opening into a toasting slot;

a carriage located within the toasting slot for holding a food item to be toasted and movable between a raised position and a lowered position;

a plurality of heating elements located within the body for toasting the food item when in the lowered position;

at least one temperature sensor for sensing the temperature within the toasting slot;

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2015275269 30 Jan 2020 a user interface for enabling a food-type selection of one of at least two different food items;

a controller for controlling the operation of the toaster, the controller being responsive to the food-type selection at the user interface and to the sensed temperature and being configured to determine an end temperature associated with the food item being in a toasted state, the calculated end temperature being dependent on an initial sensed temperature;

wherein the controller is arranged to de-energise the heating elements in response to the sensed temperature reaching the determined end temperature; and wherein the user interface comprises an inspection input causing the controller to elevate the carriage when operated during a toasting cycle to at least partially elevate the food item for inspection.

According to a further aspect of the invention there is provided a method of toasting a food item in a toaster, comprising:

a) measuring an initial temperature within the toaster;

b) determining an end temperature setpoint associated with the food item being in a toasted state, the end temperature setpoint being dependent >0 on the initial temperature;

c) energising one or more heating elements of the toaster to heat the food item;

d) causing a controller to elevate a carriage by an inspection input of a user interface when operated during a toasting cycle to at least partially elevate the food item for inspection; and

e) de-energising the one or more heating elements if a measured temperature within the toaster reaches the end temperature setpoint.

As used herein, except where the context requires otherwise, the term comprise and variations of the term, such as comprising, comprises and 30 comprised, are not intended to exclude further additives, components, integers or steps.

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Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

Figure 1A is a perspective view of a toaster with user-activated levers.

Figure 1B is a perspective view of a motorised toaster.

2a

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Figure 2 is a schematic circuit diagram of a toaster with a temperature sensor.

Figure 3 is a cut-away side view of the toaster of Figure 1A or Figure 1B along section B-B.

Figure 4 is a cut-away end view of the toaster along section A-A.

Figure 5 is a functional block diagram of the toaster of Figure 1 A.

Figure 5B is a functional block diagram of the motorised toaster of Figure 1B.

Figure 6 is a flow chart of a method of preparing an auto-ready grade of toast.

Figure 7 is an example of a relationship between an initial temperature and a target final temperature, for use in the method of Figure 6.

IO Detailed description of the embodiments

Figure 1A shows a toaster 100 with a body defining first and second cavities, shown as first and second toasting slots 102 and 104 which in use receive foodstuff to be toasted. The foodstuff could be any suitable product, typically bakery products such as bread. The body defines a base 106, side wall 108 and an upper surface 110 in 15 which openings provide passage for foodstuff to enter the toasting slots 102 and 104.

Each of the first and second toasting slots 102 and 104 is configured to receive a slice of bread. Alternatively, each cavity may be sized to receive two slices of bread next to one another.

Each toasting slot 102 and 104 has an associated lever, ie first lever 112 and 20 second lever 114 that move in slots in an end wall 109. The levers operate first and second carriages (not shown) respectively positioned within the cavities 102 and 104. Each carriage is configured to receive and hold foodstuff for toasting and is movable, through operation of the levers 112 and 114, between an elevated position in which foodstuff held by the carriage, at least in part, extends above the upper surface 110 of 25 the toaster 100 allowing for easy removal of the foodstuff and a lowered position where the foodstuff is positioned with the cavity 102, 104 for toasting.

The carriages are typically biased (directly or indirectly) to the elevated position, for example by springs. In use the user presses one or both of the levers 112, 114 to

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2015275269 22 Dec 2015 move the associated carriage into the lower position and commence toasting. The carriage may be held in place for the duration of the toasting period by a securing means such as a solenoid-controlled fastener. After a toasting period has expired, the fastener releases the carriage and the carriage springs back to the elevated position. In 5 other arrangements, the toaster includes a lifting piece (not shown) that is movable in a vertical direction. A spring biases the lifting piece upwards and a securing means such as a solenoid-controlled fastener is operable to capture the lifting piece when it is at a lower position and against the bias of the spring. The carriage rests on the lifting piece, such that when the lifting piece is captured at the lower position, the carriage drops by 10 gravity to the lowered position. When the fastener is released, the lifting piece biased by spring lifts the respective carriage to the elevated position.

To initiate toasting, the user may press one of the levers 112, 114 to move the carriages and the respective lifting piece to the lower position for the fastener to engage the lifting piece. This allows the carriage to rest in the lowered position during the 15 toasting period. Once the toasting period expires, the fastener is released, so that the lifting piece, biased by the spring, moves upwards and causes the carriage to move to the elevated position. Since the carriage rests on the lifting piece, during the toasting period a user may manipulate the lever to temporarily raise the carriage to the elevated position to inspect the toast without disengaging the fastener or disrupting the toasting ’0 cycle.

The toaster may be provided with visual indicia 115 to indicate information about the toasting cycle, or about inputs selected by a user. In some arrangements this information can be presented in a display such as a liquid crystal display.

In other arrangements, the toaster 100 may have a single lever that operates the 25 carriages associated with both toasting slots 102, 104. Alternatively, one dominant lever may activate both levers.

The toaster also has a user input 113. In the example shown, there is a button associated with a display. The user may use the button to toggle through different options and select the options that are desired. As described in more detail below, the 30 inputs provided by the user may relate to the type of bread that is placed in the toaster, and to a toaster grade setting that indicates the level of toasting chosen by the user, for

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2015275269 22 Dec 2015 example “golden brown”. In addition, there may be an option for the user to indicate that the bread placed in the toaster is frozen. The user may also be provided with a ‘cancel’ option in order to terminate a toasting cycle.

The toaster may also have an audio output such as a beeper, for example to 5 alert the user when the toast is ready.

The present disclosure also relates to a motorised toaster 151 as shown in Figure 1B. The motorised toaster 151 includes toasting slots 152 and 154 for receiving foodstuff to be heated by heating elements. One or more carriages, activated by a motor, may be raised or lowered to position the foodstuff in the toasting slots 152 and IO 154 or to raise at least part of the foodstuff outside the toasting slots. A controller, which may include a printed circuit board (PCB) receives inputs from user interfaces 157 and provides outputs that influence the motor and the heating elements. To operate the toaster 151, the user operates the user interface 157, which causes the controller to lower the carriage and to heat the heating elements for the duration of a toasting cycle. 15 At the end of the toasting cycle, the carriages are elevated by the motor to allow the foodstuff to be removed.

During the toasting cycle, the user may operate an inspection feature. The user interface 157 may include an inspection input 159, which when operated during a toasting cycle causes the controller to elevate the carriage. The toast, which is at least ’0 partially elevated outside the toasting slots, may then be inspected by the user. If the user is satisfied with the state of the foodstuff, the foodstuff may be removed from the toaster 151. Alternatively, if the user determines further heating is required, the user can operate the inspection input 159 again, causing the controller to lower the carriage to resume the toasting cycle.

In another arrangement, the user interface 157 includes a resume input 161 that is distinct from the inspection input 159. To operate the inspection feature, the user may first operate the inspection input 159 to cause the controller to elevate the carriage during a toasting cycle. If the user determines further heating is required, the user operates the resume input 161 causing the controller to lower the carriage and resume 30 the toasting cycle.

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In some arrangements, when the carriage is elevated during the inspection feature, the output of the controller ensures that the heating elements are switched off.

The examples shown have two toasting slots each. In other arrangements, the toaster may have a different number of cavities. For example, other arrangements 5 include a four-slice parallel toaster and a four-slice inline toaster. Within each cavity there is a centring guide 305 that acts to centre foodstuff in the respective toasting slots. As the carriage bearing the foodstuff moves to the lowered position, centring guides 305 on opposing sides of each toasting slot move towards one another, thereby centring the foodstuff to the centre of the respective cavity. The centring guides 305 include wire 10 frames that are located on opposing side walls of the respective cavity. A pair of centring guides on opposing walls of toasting slots can pivot inwardly towards one another to centre foodstuff located between the guides. When the carriage assembly is raised, the centring guides 305 move apart from one another to facilitate extraction of the foodstuff.

Referring to Figure 2, a first heating assembly 116 and a second heating assembly 118 are respectively associated with the first and second toasting slots 102 and 104 (or 152 and 154). These heating assemblies 116 and 118 are positioned on or adjacent the walls defining the cavities 102 and 104 and may be activated to heat the cavities 102 and 104, thereby heating and toasting the foodstuff received within the ’0 cavities. The heating assemblies may be resistive windings mounted on mica card, or alternatively a resistance wind without a mica card. In other arrangements the heating assemblies 116, 118 may include a halogen, ceramic or printed heating element.

A temperature sensor 140 is positioned within the interior of the toaster 100, 151 in order to provide an indication of the heating temperature experienced by the 25 foodstuff. A temperature signal 142 measured by the temperature sensor is provided to a controller 128. As described in more detail below, the toasting cycle is dependent on the measured temperature.

In one arrangement, the temperature sensor 140 is an NTC thermistor. The resistance of the thermistor varies dependent on temperature. In other arrangements 30 there may be a plurality of temperature sensors, for example each being associated with a respective toasting slot.

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In the toaster 100, the first lever 112 is associated with the first heating assembly 116 so that when the user presses the lever 112 to move the first carriage to its lowered position, a first heating assembly switch 120 is activated. For example a pair of contactors may be connected or closed when the lowered position of the lever 112 is 5 reached. This turns the first heating assembly 116 on. Similarly, the second lever 114 is associated with the second heating assembly 118 so that pressing the lever 114 down to move the second carriage to its lowered position activates a second heating assembly switch 122, turning the second heating assembly 118 on. The heating assemblies 116 and 118 are switched on as the respective switches 120 and 122 I0 connect the assemblies to a power source, typically through a power plug. The power source is represented in Figure 2 by an active line 124 and a neutral line 126.

The operation of the toaster is controlled by a controller 128. This may be a micro-controller or any other device which provides the necessary logic for the toaster circuitry. The controller 128 receives signals indicating that a toasting cycle should 15 commence. For example, this occurs when the levers 112, 114 are lowered, or when the motorised carriage in toaster 151 is lowered to the toasting position. The controller 128 is in data communication with the switches 120, 122 such that at the end of a toasting cycle, the controller 128 can cause the switches 120, 122 to open, ending the supply of power to the heating assemblies 116, 118.

’0 The toaster may have a bagel mode for toasting bagels or crumpets. In the bagel mode heating only occurs on one side of a toasting slot. A return run of heating assemblies 116, 118 may be bypassed using a relay. When the bagel mode is selected, one side of the heating chamber 102, 104 is energised and the other side of the heating chamber is de-energised during the toasting cycle.

Figure 3 is a cut-away schematic diagram looking from the interior of the elongate slot 102 towards the side 108 of the toaster, along section B-B in Figure 1B. Part of the centring guide 305 is visible, including five vertical bars forming a type of cage that, in use, presses the toast towards the centre of the cavity 102. Behind the centring guide 305, part of the heating assembly 116 is visible. A rectangular mica card

305 is positioned adjacent to the toasting slot 102. A circuitous electrical winding 301 is positioned on the mica card 303, on the side of the card closest to the cavity 102. In

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2015275269 22 Dec 2015 use, the electrical winding 301 provide electrical resistance that produces heat when electrical current is applied.

In the illustrated embodiment, the temperature sensor 140 is located approximately centrally in the mica card 303. The sensor is housed in a ceramic tube 5 401 that shields the sensor 140 from the heating elements 301. Other heat-shielding materials may also be used.

The location of the temperature sensor is further illustrated in the cut-away end view of Figure 4, which looks from the interior to an end wall, e.g.109, along section AA. The temperature sensor 140 is contained in tube 401 made of a heat-shielding I0 material such as ceramic that projects through a hole in the mica card 303 to access the interior of the cavity 102. In an alternative arrangement the sensor 140 does not project through the mica card 303, but is recessed behind the mica card 303. In this arrangement a shielding tube 401 may not be needed as the mica card 303 provides shielding from the heating elements 301. The sensor monitors the temperature in the 15 interior of the cavity 102 through an orifice in the mica card.

This view shows further the configuration of the centring guides 305, which are configured to hold toast within toasting slots 102 and 104 respectively.

In the depicted arrangement, the mica card 320 in the centre of the toaster between cavities 102 and 104, has electrical windings on both sides of the mica card ’0 320 in order to produce heat for both cavities.

Figure 5A is a functional plot diagram of a toaster that uses a manual lever to move the toast, for example the toaster 100 seen in Figure 1A. The toaster includes a main printed circuit board 501 that contains the power supply circuit and also the controller 128. The PCB 501 communicates with the heating elements 116, 118 and 25 also with the temperature sensor 140.

The functional block 503 designates a user interface configured to receive various inputs from the user, and also to provide output information. The inputs enable the user to select a toaster grade setting. This enables the user to specify the extent to which the toast is to be toasted. For example, the toaster grade could be “lightly 30 toasted” or “golden brown”.

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Another user input enables the user to select a type of bread that is to be placed in the toaster. This is because different types of bread require different amounts of heat to achieve the desired level of toasting.

A further user input enables the user to specify that the bread toasted in the 5 toaster is frozen. In this case, additional heating is required.

The user interfaces also include a “cancel” input that enables the user to terminate a toasting cycle.

There are several ways in which the user interfaces may be implemented. There may be a separate input for each of the specified inputs. For example, the toaster grade 10 setting and the bread type selection may be entered using different input means. In one example, the user may rotate a dial with a pointer that indicates one of several choices. The toaster may have a separate button for each bread type. Alternatively, the current option may be displayed on a display and the user may activate a toggle switch to move between options. In another arrangement, the user interface may include a touch 15 screen that enables the user to make a selection by touching on a desired option. Feedback about a current selection may be provided via an LCD display. Alternatively or in combination, feedback may be provided to the user by illuminating an LED with associated text or graphics. For example, an LED can indicate that brown bread has been selected, or an LED can indicate that a “golden brown” setting has been selected.

’0 The cancel input may be provided as a separate input so it is easy to locate in the event that the user wishes to terminate the toasting cycle. The user output may include one or more LEDs, one or more liquid crystal displays (LCDs), and an audio output such as a beeper. The beeper may, for example, indicate that the toast is ready. The PCB 501 also communicates with functional block 505 that designates the carriage 25 sense mechanism and the lock/release mechanism for the carriage. As mentioned above, the lock/release mechanism may include a solenoid controlled fastener. Thus, at the end of the toasting cycle, the PCB can interrupt power to the fastener. Consequently, the fastener releases the carriage or lifting piece and the carriage springs back to its elevated position.

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Figure 5B shows a function of block diagram for a motorised toaster such as that shown in Figure 1B. The functional configuration 550 is similar to that seen in Figure 5A. The difference is that the carriage is raised and lowered by a carriage motor 555, rather than relying on the carriage sense and lock/release mechanism 505.

The PCB 551 communicates with the temperature sensor 140 and the heating elements 116, 118. The user interface 553 includes the functionality previously described for the user interface 503. In addition, further inputs are required to enable the user to start the motor, causing the carriage to move down to the toasting position.

Figure 6 shows a flow diagram 600 for a method of preparing an auto-ready I0 grade of toast, using the toasters described above. The method commences at stage 601, in which the toaster is powered up and ready to receive inputs. In process 603, the user enters the type of bread that is to be placed in the toaster for toasting. In step 605 the controller 128 checks whether the user has specified white bread. If not, in step 607 the controller checks whether the user has entered brown bread. If not, in step 609 the 15 controller checks whether the user has entered rye bread. If not, the controller checks whether the user has entered sweet bread. If none of the available options is selected (eg the NO output of step 611), the controller returns to the ready mode 601. The different options for bread type may be presented in a different order. In addition, further options for types of bread may be added to or removed from the list of options shown in ’0 Figure 6.

Once a bread type has been selected (the YES option of any one of steps 605, 607, 609, 611), then process flow proceeds to step 613. Here, the controller retrieves an algorithm that has been previously assigned for the selected bread type. As described below, the chosen algorithm determines a final temperature set point that is dependent 25 on:

• the selected bread type;

• the specified toaster grade setting; and • an initial temperature measured within the elongated cavities (eg 102, 104).

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Step 615 enables the user to specify the desired toast grade. The example of Figure 6 shows step 615 following the bread type selection. The order may be reversed. Alternatively, the two selections 603, 615 may be scanned in parallel.

If the bread type has been selected in process 603 and the toaster grade entered in process 615, process flow continues to step 617, in which the controller checks whether the user has commenced a toasting cycle. In the case of the toaster with a manual lever, the information is provided to the PCB 501 from the carriage sense mechanism 505. In the case of a motorised toaster 550, the information may be provided from the carriage motor 555 or by detecting from the user interface 553 that 10 the user has pressed a start option.

If the user does not commence a toasting cycle (the NO option of step 617) then process flow returns to the ready mode 601. If the user does commence a toasting cycle, then in process 619 the controller 128 registers the temperature of the toaster’s chamber using the temperature sensor 140. In step 621, the measured temperature is 15 registered into the selected algorithm assigned for the bread type and toast grade. The algorithm specifies a final temperature set point.

In step 623 heat is provided to the toasting chamber by the heating elements 116, 118, as supervised by the controller 128.

In process 625 the controller polls whether the cancel button has been activated. ’0 If NO then process flow continues to step 627. If the cancel button is activated (the YES option of step 625) then process flow continues to step 629 to end the toasting cycle.

In process 627, the controller monitors the temperature in the toasting chamber as measured by the temperature sensor 140. If the final set point specified by the algorithm has not been reached, then toasting continues in step 623. If the final 25 temperature has been reached then process flow continues to step 629. The heating elements 116, 118 are de-energised to stop heating of the toasting chamber. In addition, the carriage may be raised to enable the user to access the toast. This may be done either by the lock/release mechanism 505 or by activation of the carriage motor 555. Once the toasting cycle is terminated or cancelled, process flow returns to the 30 ready mode 601.

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Figure 7 shows a curve illustrating an algorithm that may be used to determine a final temperature set point in the algorithm of method 600. The example shown is for white bread where a “golden brown” setting has been selected.

The x axis in Figure 7 shows the input temperature in degrees Celsius. This represents the measured temperature at the start of the toasting cycle, as measured in step 619 of method 600.

The y axis of Figure 7 is the required final temperature set point.

The relationship shown in Figure 7 is obtained by repeated experiments, in which white bread is toasted to a golden brown level. The experiments are repeated, starting with different initial temperatures within the toaster. The temperature profile is monitored during toasting to the desired final stage, and the final temperature of the toasting chamber is recorded. Figure 7 shows the experimental results for a series of tests and also a linear fit to the results.

The experiments are repeated for each different type of bread and for each toast grade. The algorithms can be stored in several ways in the controller 128. For example, equations may be stored, allowing the final temperature set point to be calculated based on a measured initial temperature. Alternatively, the results may be stored as a look-up table.

As discussed above, and depicted in functional blocks 503 and 553 of Figures 5A and 5B, respectively, the user interface of the toaster of the present embodiment may have an option for the user to indicate that the bread or foodstuff placed in the toaster is frozen. In an alternative embodiment, the user interface may also include an option for the user to indicate further functional settings in addition to normal toasting and a toasting from frozen setting. These additional functional settings of the toaster include, but are not limited to, a reheating setting and a grade+ setting.

The reheating setting can be selected when a user wishes to reheat the bread or foodstuff that has already been toasted and allowed to cool down. The grade+ setting can be selected when the user wishes to re-toast the bread or foodstuff just enough so as to attain the next toaster grade fraction setting (B0-, B0, B0+, B1-, B1, B1+, etc). For example, if the user had previously specified a toaster grade setting of B1 for an initial

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2015275269 22 Dec 2015 toasting cycle, and then selects the grade+ setting after the completion of this initial toasting cycle, the already toasted bread or foodstuff would then undergo a further toasting cycle to attain a toaster grade setting of B1+. The grade+ setting may be configured such that it only operates when it is selected by the user within a 5 predetermined time period of the initial toasting cycle completing, e.g. within 30 seconds of completion, and/or if a temperature measured within the elongated cavities is within a specified temperature range, e.g. the measured temperature is hotter than 80% of a target temperature of the initial toasting cycle.

A method of preparing an auto-ready grade of toast in accordance with the

IO present embodiment using a toaster that includes these additional functional settings generally corresponds to the method of the previous embodiment. Accordingly, this alternative method follows a process flow similar to the method disclosed above and depicted in the flow diagram 600 of Figure 6, and the corresponding method steps thus need not be repeated here in detail. However, in addition to the parameters utilised in 15 the previously described method, the algorithm of this alternative method used to determine the final temperature set point is further dependent upon the additional functional settings.

As a result of the additional algorithm parameter, the process flow of the alternative method includes a further process flow step between, or parallel to, steps ’0 603 and 615. This further process flow step involves polling whether one or more of the additional functional settings has been selected. As a result, step 613 is modified such that the controller retrieves an algorithm that has been previously assigned not only for the selected bread type, but also for the additional functional setting.

Similar to the method of the previously described embodiment, the retrieved 25 algorithm is then used to calculate a final temperature set point based upon the additional parameters of the specified toaster grade setting and an initial temperature measured within the elongated cavities. The algorithm may be stored in the controller as an equation, as a look-up table or even a combination of equation and look up table.

The following Tables 1 to 4 are examples of possible look up tables that can be used to determine target temperatures required to obtain specified toasting grades.

These tables have been experimentally derived by toasting standard thin bread slices

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2015275269 22 Dec 2015 (10 mm thick), starting from room/ambient temperature, in a toaster having particular thermal properties and a specific mechanical construction. Different bread and foodstuff types will have different temperature parameters, and toasters having different constructions and/or thermal properties will naturally have different thermal response 5 characteristics and provide look up tables with other temperature values.

Table 1. Normal toasting:

	Toasting Grade
Bread type	B0	B3	B5
White bread	125 °C	155 °C	165 °C
Wholemeal bread	120 °C	140 °C	170 °C
Raisin bread	105 °C	130 °C	N/A

Table 2. Reheat toasting:

	Toasting Grade
Bread type	B0	B3	B5
White bread	65 °C	75 °C	65 °C
Wholemeal bread	60 °C	70 °C	85 °C
Raisin bread	55 °C	65 °C	70 °C

IO Table 3. Grade+ toasting:

Table 4. Frozen toasting:

	Toasting Grade
Bread type	B0	B3	B5
White bread	140 °C	170 °C	180 °C
Wholemeal bread	135 °C	155 °C	170 °C
Raisin bread	120 °C	145 °C	N/A

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As discussed above, these example look up tables were generated based upon toasting experiments that were conducted starting from room/ambient temperature. Room/ambient temperature may be measured by an additional temperature sensor provided within the toaster housing, or conveniently by the existing temperature sensor 5 when the toaster has been off for longer than a predetermined period of time. Room/ambient temperature may also be determined based upon a temperature that is measured by the existing sensor and remains constant for longer than a predetermined period of time. Alternatively, room/ambient temperature may correspond to a predetermined temperature that may be set at the time of manufacture of the toaster, or 10 may be set via input from the user.

Additional look up tables can be generated based upon experiments that are conducted starting from various, other temperatures. Alternatively, the retrieved algorithm may comprise an adjustment calculation that can account for initial temperatures that deviate from room/ambient temperature.

For example, if the initial temperature within the toaster is cooler, or less than 1 °C hotter, than room/ambient temperature, the algorithm can be set to return the original target temperature determined by the look up table as the final target temperature. However, if the initial temperature within the toaster is hotter than room/ambient temperature by more than 1 °C, then the algorithm can be set to calculate the final ’0 target temperature based upon the original target temperature and an additional correction function used to account for this deviation. Expressed in the form of an “If Then - Else” statement, an example of an algorithm including such an adjustment calculation comprises the following Equations 1,2 and 3.

If:

Ti - T_A > 1 °C (Equation 1)

Then

T_F = c (^-) T_o + T_o (Equation 2)

Else

T_F = T_o (Equation 3)

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Where:

Τι = Initial temperature measured within the elongated cavities

Ta = Room/ambient temperature

To = Original target temperature (determined from the lookup table)

T_F = Final target temperature c = Correction factor

As the described method determines the completion of a toasting cycle based upon measured temperature rather than time, an advantage is that it can provide a consistent level of toasting, even when the toaster has previously been used, resulting 10 in a different temperature within the toasting chamber.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

1. A toaster comprising:

a body having at least one opening into a toasting slot;

a carriage located within the toasting slot for holding a food item to be toasted

5 and movable between a raised position and a lowered position;

IO a user interface for enabling a food-type selection of one of at least two different food items;

a controller for controlling the operation of the toaster, the controller being responsive to the food-type selection at the user interface and to the sensed temperature and being configured to determine an end

15 temperature associated with the food item being in a toasted state, the calculated end temperature being dependent on an initial sensed temperature:

wherein the controller is arranged to de-energise the heating elements in response to the sensed temperature reaching the determined end >0 temperature: and wherein the user interface comprises an inspection input causing the controller to elevate the carriage when operated during a toasting cycle to at least partially elevate the food item for inspection.

25

2. The toaster of claim 1 wherein the controller causes the carriage to be moved to the raised position in response to the sensed temperature reaching the determined end temperature.

3. The toaster of claim 1 or 2 wherein the user interface enables a toast grade

30 selection that specifies a desired degree of toasting desired for the toasted state, and wherein the controller determines the end temperature dependent on the food-type selection; the toast grade selection; and the initial sensed temperature.

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4. The toaster of claim 1 or 2 wherein the user interface enables a toast grade selection that specifies a desired degree of toasting desired for the toasted state and an additional functional setting selection that specifies one of a normal toasting setting, a toasting from frozen setting, a reheating setting and a grade+

5 setting, and wherein the controller determines the end temperature dependent on the food-type selection; the additional functional setting selection; the toast grade selection; and the initial sensed temperature.

5. The toaster of any one of the preceding claims wherein the food-type selection

IO enables selection of two or more of: white bread; brown bread; rye bread; sweet bread; crumpet; and bagel.

6. The toaster of any one of the preceding claims wherein the controller determines the end temperature based on at least one of an algorithm or look-up table.

I5

7. The toaster of any one of the preceding claims wherein the temperature sensor is an NTC thermistor.

8. The toaster of any one of the preceding claims having a bagel mode in which >0 heating elements on one side of the toasting slot are energised while heating elements on an opposite side of the toasting slot are de-energised during toasting.

9. A method of toasting a food item in a toaster, comprising:

a) measuring an initial temperature within the toaster;

b) determining an end temperature setpoint associated with the food item being in a toasted state, the end temperature setpoint being dependent on the initial temperature;

2015275269 30 Jan 2020

10.The method of claim 9 comprising:

5 receiving via the user interface a food-type selection of one of at least two different food items; and wherein the end temperature setpoint is determined for the selected food item.

11 .The method of claim 10 comprising:

I0 receiving via the user interface a toast-grade selection of one of at least two different toasting states, and wherein the end temperature setpoint is dependent on the toast-grade selection.

12. The method of claim 10 comprising:

15 receiving via the user interface an additional functional setting selection that specifies one of a normal toasting setting, a toasting from frozen setting, a reheating setting and a grade+ setting, and wherein the end temperature setpoint is dependent on the additional functional setting selection .

>0

13. The method of claim 10 wherein the food-type selection enables selection of two or more of: white bread; brown bread; rye bread; sweet bread, crumpet and bagel.