GB2513400A

GB2513400A - Cooking appliance, cooking hob and method for determining a cooking appliance characteristic

Info

Publication number: GB2513400A
Application number: GB1307557.7A
Authority: GB
Inventors: Barry Philip Ward
Original assignee: Morphy Richards Ltd; Morphy Richards NI Ltd
Current assignee: Morphy Richards Ltd; Morphy Richards NI Ltd
Priority date: 2013-04-26
Filing date: 2013-04-26
Publication date: 2014-10-29
Anticipated expiration: 2033-04-26
Also published as: GB2513400A8; GB2513400B; GB201307557D0

Abstract

The cooking hob includes spaced electrically conductive hob rails HR1-HR3 protruding from the outer support surface. Driver 530 with an output coupled to the inductive coils 430 is coupled to a controller and associated appliance decoder modules 535. Each appliance decoder 535 has decoder outputs and inputs selectively coupled to the electrically conductive hob rails. The decoder identifies a cooking appliance seated on the hob rails by use of a resistance circuit R1 carried on mount 120 of the cooking appliance 100 which mount supports electrically isolated conductive base rails BR1-BR3. BR1 and BR2 are connected by the resistance R1 whilst BR2 and BR3 are connected by a thermistor circuit TC which thermally engages the base 115 of the vessel. The decoder module determines the appliance type by outputting a reference voltage via the rails to the resistance circuit and receiving the attenuated voltage and comparing it with stored tables in the memory module 515. The decoder has three inputs/outputs, each output being from a tri-state buffer which allows the system to be non-orientation sensitive. An attenuated signal from the thermistor circuit is similarly acquired and compared to ascertain vessel temperature.

Description

COOKING APPLIANCE, COOKING HOB AND METHOD FOR DETERMINING

A COOKING APPLIANCE CHARACTERISTIC

Field of the Invention

[0001] The present invention relates to cooking appliances, cooking hobs and a method for determining a characteristic such as a cooking profile for a cooking appliance seated on a cooking hob. The invention is particularly useful for, but not necessarily limited to, identifying a cooking profile or cooking characteristic to at least reduce the requirements for a user to select cooking temperatures (or hob settings) for a specific cooking appliance.

Background ot the Invention

[0002] Some cooking appliances are known to have radio transmitters for wireless communication with cooking hobs. This wireless communication can be used to provide characteristics and current temperature of the cooking appliance to the cooking hob. However, the radio transmitter should either be in a watertight chamber or removable from the appliance so that moisture does not come into contact with the circuitry of the transmitter during washing of the appliance. Furthermore, these appliances are relatively expensive due to the additional circuitry of the transmitter and also require a battery or other power storage means. Such transmitters also need to be kept away from the high temperatures and thus are typically stored in a handle of the appliance which can be at a distance of as much as 10 to 15 cm from the cooking hob. It would therefore be beneficial if the characteristics of the appliance could be communicated to the cooking hob without the need for radio transmitters. It would also be useful if the temperature of the appliance could be communicated to the cooking hob especially when the coking hob is an induction hob

Summary of the Invention

[0003] According to a first aspect of the present invention, there is provided a cooking appliance for use on a cooking hob, the appliance including: a cooking vessel; a base for seating the vessel on the cooking hob, the base including at least one electrically insulating mount; at least two spaced electrically conductive base rails mounted to the electrically insulating mount; and a resistance circuit electrically coupling the two spaced electrically conductive base rails.

[0004] Suitably, there are three said spaced electrically conductive base rails mounted to the electrically insulating mount, the base rails being a first, second and third base trail, and wherein the resistance circuit electrically couples the first base rail to the second base rail and a thermistor circuit electrically couples the second base rail to the third base rail.

[0005] Preferably, the base rails protrude from the electrically insulating mount.

[0006] Suitably, the base rails are of equal length.

[0007] Preferably, the base rails have an arcuate track profile when the base is viewed in a plan view.

[0008] Suitably, each of the base rails has an arcuate track profile of each of the base rails covers a circumference of approximately 120 degrees.

[0009] Preferably, the base rails are located adjacent an outer periphery of the electrically insulating mount.

[0010] Suitably, the resistance circuit is a single resistor.

[0011] Preferably, the thermistor circuit includes a resistor in series with a thermistor.

[0012] Suitably, the thermistor circuit is a thermistor coupled directly across the second rail and the third base rail.

[0013] Preferably, there is a ferrous based inductive heating member forming part of the base.

[0014] Suitably, the thermistor is located proximal to the cooking vessel.

[0015] Preferably, there is a set of cooking appliances according to the first aspect of the present invention, wherein the resistance circuit uniquely identifies each of the appliances from the other appliances in the set.

[0016] According to a second aspect of the present invention, there is provided cooking hob including: a support with an outer support surface; spaced electrically conductive hob rails protruding from the outer support surface; at least one inductive coil; a driver having an output coupled to the inductive coil; a controller coupled to the driver; and an appliance decoder coupled to the controller, the appliance decoder having decoder outputs selectively coupled the electrically conductive hob rails and decoder inputs selectively coupled the electrically conductive hob rails.

[0017] Suitably, in operation the appliance decoder supplies a reference voltage to a first one of the electrically conductive hob rails and a resistor circuit in a cooking appliance seated on the conductive hob rails modifies the reference voltage to provide an appliance identification voltage at a second one of the electrically conductive hob rails.

[0018] Preferably, in operation the appliance decoder processes the appliance identification voltage to determine a characteristic of the cooking appliance seated on the conductive hob rails.

[0019] Suitably, the characteristic is a cooking profile of the cooking appliance seated on the conductive hob rails.

[0020] Preferably, there is a memory module coupled to the controller, wherein the memory module includes cooking appliance orientation identification values.

[0021] Suitably, the cooking appliance orientation identification values include an appliance identification set of valid voltage ranges associated with respective cooking appliances.

[0022] Preferably, appliance orientation identification values include a secondary valid voltage range associated with the respective cooking appliances.

[0023] Suitably, the appliance identification set of valid voltage ranges cover a different voltage range to that of the secondary valid voltage range.

[0024] Preferably, the appliance identification values include an output voltage value to be selectively provided to one of the hob rails.

[0025] Suitably, the hob rails are radially positioned relative to a central area.

[0026] Preferably, there are three hob rails that radially extend at an angle of degrees from each other.

[0027] Suitably, each of the decoder outputs is a tn-state output.

[0028] Preferably, decoder includes three outputs and three inputs, wherein each one of the outputs is an output from a tn-state buffer.

[0029] According to a third aspect of the present invention, there is provided a method for determining a cooking appliance characteristic, the method including: method for determining a cooking appliance characteristic, the method being performed by a cooking hob and the method including: sending a reference voltage to a first one of a plurality of electrically conductive hob rails supporting a cooking appliance thereon; attenuating the reference voltage by a resistor circuit mounted in the appliance to provide an appliance identification voltage at a second one of the electrically conductive hob rails; and processing the appliance identification voltage to determine the cooking appliance characteristic.

[0030] Suitably, the sending is performed by a tn-state buffer.

[0031] Preferably, the processing includes comparing the appliance identification voltage with an appliance identification set of valid voltage ranges.

[0032] Suitably, the method includes a further process of attenuating the reference voltage by a thermistor circuit mounted in the appliance to provide a temperature dependent voltage at a third one of the electrically conductive hob ra i Is.

[0033] Preferably, there is an additional process of controlling heat supplied to the appliance based on the temperature dependent voltage and the cooking appliance characteristic.

[0034] Suitably, method is performed by the cooking hob according to the second aspect of the present invention.

[0035] Preferably, the cooking appliance is the cooking appliance according to the first aspect of the present invention.

[0036] Further aspects of the present invention are as set out in the claims herein.

Brief Description of the Drawings

[0037] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 is a top plan view of a cooking appliance for use on a cooking hob in accordance with a preferred embodiment of the present invention; Figure 2 is an underside plan view of the cooking appliance of Figure 1 in accordance with a preferred embodiment of the present invention; Figure 3 is a cross sectional side view, through 3-3', of the cooking appliance of Figure 1 in accordance with a preferred embodiment of the present invention; Figure 4 is a schematic diagram a cooking hob in accordance with a preferred embodiment of the present invention; Figure 5 is a schematic block diagram of an electric circuit that is part of the cooking hob of Figure 4 in accordance with a preferred embodiment of the present invention; Figure 6 is a schematic diagram of an appliance decoder module that is part of the electric circuit of Figure 5, in accordance with a preferred embodiment of the present invention; Figure 7 is illustrated a top plan view of a first assembly orientation including the cooking appliance of Figure 1 and cooking hob of Figure 4 in accordance with a preferred embodiment of the present invention; Figure 8 is a schematic circuit diagram at specific terminals of the appliance decoder module of Figure 6 when the cooking appliance of Figure 1 and cooking hob of Figure 4 are in the first assembly orientation; Figure 9 is illustrated a top plan view of a second assembly orientation including the cooking appliance of Figure 1 and cooking hob of Figure 4 in accordance with a preferred embodiment of the present invention; Figure 10 is a schematic circuit diagram at specific terminals of the appliance decoder module of Figure 6 when the cooking appliance of Figure 1 and cooking hob of Figure 4 are in the second assembly orientation; Figure 11 is illustrated a top plan view of a third assembly orientation including the cooking appliance of Figure 1 and cooking hob of Figure 4 in accordance with a preferred embodiment of the present invention; Figure 12 is a schematic circuit diagram at specific terminals of the appliance decoder module of Figure 6 when the cooking appliance of Figure 1 and cooking hob of Figure 4 are in the third assembly orientation; and Figure 13 is a flow diagram illustrating a method for determining a cooking appliance characteristic in accordance with a preferred embodiment of the present invention.

Detailed Description of the Embodiments

[0038] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to

unnecessarily obscure the description.

[0039] Referring to Figure 1 there is illustrated a top plan view of a cooking appliance 100 for use on a cooking hob in accordance with a preferred embodiment of the present invention. The cooking appliance 100 includes a cooking vessel 105 that provides a cooking chamber 110 and there is a base 115 for seating the vessel 105 on the cooking hob. The base 115 includes an electrically insulating mount 120 and there are spaced electrically conductive base rails which in this embodiment are a first base rail BR1, a second base rail BR2 and a third base trail BR3 each mounted to the electrically insulating mount 120.

[0040] There is a resistance circuit in the form of a single identifier resistor Ri electrically coupling two of the spaced electrically conductive base rails. In this embodiment the identifier resistor Ri couples the first base rail BR1 to the second base rail BR2. There is also a thermistor circuit TC that electrically couples the second base rail BR2 to the third base rail BR3. As shown, in this embodiment there is no single electrical circuit on, or in, the appliance 100 that electrically couples the third base rail BR3 to the first base rail BR1.

[0041] Referring to Figure 2 there is illustrated an underside plan view of the cooking appliance 100 for use on a cooking hob in accordance with a preferred embodiment of the present invention. As shown, the first, second and third base rails BR1, BR2, BR3 are of equal length and have an arcuate track profile when the base is viewed in this underside plan view. Furthermore, the first, second and third base rails BR1, BR2, BR3 each cover a circumference of approximately 120 degrees and adjacent edges of the base rails BR1, BR2, BR3 are space by a respective gap 205, 210, 215. More specifically, in this embodiment the first, second and third base rails BR1, BR2, BR3 each cover a circumference of 115 degrees and each respective gap 205, 210, 215 covers cover a circumference of 5 degrees.

[0042] Referring to Figure 3 there is illustrated a cross sectional side view, through 3-3', of the cooking appliance 100 in accordance with a preferred embodiment of the present invention. As illustrated, the base rails BR1, BR2, BR3 protrude from the electrically insulating mount 120. Also, to provide for suitable stability of the appliance 100, when mounted on a cooking hob, the base rails BR1, BR2, BR3 are located adjacent an outer periphery 305 of the electrically insulating mount 120.

[0043] The cooking vessel 105 is typically press formed from a metal sheet such as steel or aluminium and a ferrous based inductive heating member 310 is welded, braised or otherwise fixed to an underside of the cooking vessel and forms part of the base 115. For aesthetic appeal, an aluminium or copper plate 315 is braised or otherwise fixed on an underside ot the ferrous based inductive heating member 310. The electrically insulating mount 120 is typically a ceramic or plastics annulus bonded to both the underside of the cooking vessel 110 and a periphery of the ferrous based inductive heating member 310. The component or components of both the identifier resistor Ri and thermistor circuit TC are located in holding slots in the electrically insulating mount 120, and the identifier resistor Ri and thermistor circuit TC are connected to their respective base rails BR1, BR2, BRS by spot welding or high temperature solder joints. Also, as shown to limit heat exposure of the identifier resistor Ri, the holding slot for the identifier resistor Ri is located away from the cooking vessel 105.

[0044] The thermistor circuit TC in one embodiment includes a 55KOhm resistor in series with a Negative Temperature Coefficient Thermistor NTCT. In another embodiment, the thermistor circuit TC is a Negative Temperature Coefficient Thermistor NTCT coupled directly across the second rail and the third base rail. The Negative Temperature Coefficient Thermistor NTCT is located proximal to the cooking vessel 105 in order to more accurately sense the temperature of food being cooked in the cooking vessel 105. In the embodiment where the thermistor circuit TO includes a 55KOhm resistor in series with a Negative Temperature Coefficient Thermistor NTCT, the resistance of the Negative Temperature Coefficient Thermistor NTCT varies with temperature as

shown in table 1.

TEMPERATURE °C RESITANCE -25 1.3OSMOhm ZERO 326K0hm +25 lOOKOhm +50 36KOhm +75 lSKOhm -1-100 6.SKOhm +125 3.4KOhm +150 1.5KOhm Table 1, resistance values for variations in temperature for the NTCT.

[0045] The resistance circuit in the form of the identifier resistor Ri has a resistance value RV that is dependent on the type of cooking appliance 100 to which it is mounted or associated. In this embodiment the resistance circuit identifier resistor Ri has a resistance value RV divisible by 5KOhms. The present invention thus provides for a set of cooking appliances 100 and the identifier resistor Ri resistance value RV uniquely identifies each of the appliances 100 (appliance type) from the other appliances 100 in the set. Alistof such a set of appliances 100 (appliance types) and associated resistance values RVs is shown in table 2. It should be noted that the set of appliances in table 2 is just an example of appliance types and further appliance such as a rice cooker, a standard pan, a mini oven or other appliances can be included in table 2.

RESITANCE VALUES RVS APPLIANCE TYPE

SKOhm SOUSVIDE lOKOhm SLOW COOKER lSKOhm STEAMER 2OKOhm SOUP MAKER 2SKOhm DEFROSTER 3OKOhm GRILL 35KOhm DEEP FAT FRIER Table 2, appliance type and associated resistance values RVs.

[0046] Referring to Figure 4, there is illustrated a schematic diagram of a cooking hob 400 in accordance with a preferred embodiment of the present invention. The cooking hob 400, which is an induction hob, includes a support 405 with an outer support surface 410 that is often known as an appliance support surface when referring to conventional known hobs. The support 405 is an electric insulator typically made from a glass based or ceramics based material, and in this embodiment there are two appliance cooking regions 415 provided by the cooking hob 400. However, a single or more than two appliance cooking regions 415 can also be provided. Each of the appliance cooking regions 415 have a guide circle 420 displayed on the support 405 for indicating where a cooking appliance should be located. There are set of electrically conductive hob rails HR1, HR2, HR3 associated with each of the appliance cooking regions 415. In this embodiment the electrically conductive hob rails are a first hob rail HR1, a second hob rail HR2 and a third hob rail HR3 that protrude from the outer support surface 410. The bob rails HR1, HR2 and HR3 are radially positioned relative to a central area 425 of their respective cooking regions 415. Furthermore, the hob rails HR1, HR2 and HR3 are spaced equal distances apart at angle 120 of degrees from each other.

[0047] The cooking hob 400 has an inductive coil or coils 430 (shown in phantom) for each of the appliance cooking regions 415. There is also a user interface 435 that allows a user to, for instance, view temperature readings, hob settings, appliance type automatically identified by the hob 400 and cook times as well as allowing input control commands such as cooking region 415 selection as will be apparent to a person skilled in the art.

[0048] Referring to Figure 5 there is illustrated a schematic block diagram of an electric circuit 500 that is part of the cooking bob 400 in accordance with a preferred embodiment of the present invention. The electric circuit 500 includes a controller unit 505 to which are coupled a clock 510, the user interface 435 and a memory module 515. The memory module 515 stores, amongst others, cooking profile control instruction sets IS, valid cooking appliance identification orientation identification value tables (tables 3 to 5) and a voltage to temperature conversion table (table 6). The details of tables 3 to 6 will be described in more

detail later in this specification.

[0049] The user interface 435 has a visual display 520 and user controls 525 for allowing a user to view and optionally select: menus; time settings; cooking profiles; hob region (cooking ring) selection; temperature settings; and other cooking requests and data. However, if the one of the set of cooking appliances 100 is placed on one of the appliance cooking regions 415 the user may not necessarily need to select setting and the like by using the user controls 525. Furthermore, the user controls 525 may be a touch screen and both the user controls 525 and visual display 520 can be integrated into a single touch screen region.

[0050] The electric circuit 500 also includes the two inductive coils 430 coupled to drive outputs of a driver 530. The driver 530 is coupled to and controllable by the controller unit 505. There are also appliance decoder modules 535 coupled by a bus 540 to the controller unit 505 and the appliance decoder modules 535 each have outputs connected to a respective one of the electrically conductive hob rails HR1, HR2, HR3 associated with one of the inductive coils 430.

[0051] Referring to Figure 6, there is illustrated a schematic diagram of an appliance decoder module 535 that is part of the electric circuit 500 in accordance with a preferred embodiment of the present invention. The appliance decoder module 535 has an decoding logic module 605 coupled to the bus 540 and three outputs of the decoding logic module 605 are coupled to respective control inputs of tn-state buffers 610, 615, and 620. In this embodiment, inputs of the tn-state buffers 610, 615, and 620 are coupled to a 5 Volts supply rail however, other voltages can be used. Outputs of the tn-state buffers 610, 615, and 620 provide respective outputs OP1, OP and 0P3 of the appliance decoder module 535. As shown, the outputs OP1, OP and 0P3 are connected to inputs IP1, 1P2 and 1P3 of respective analogue to digital converter modules 625, 630, 635 such that both OP1 and HR1 potentially provide an input voltage to module 625, both OP2 and HR2 potentially provide an input voltage to module 630, and both 0P3 and HR3 provide an input voltage to module 635.

[0052] Control outputs from the decoding logic module 605 are selectively coupled to control inputs of the analogue to digital converter modules 625, 630,635 and outputs of the analogue to digital converter modules 625, 630,635 are coupled to a multi-output bit multiplexer 640. In this embodiment the outputs from each analogue to digital converter module 625, 630,635 are 8 bits and therefore the output of the multiplexer 640 is also 8 bits. The multiplexer 640 is controlled by signals sent on the lines of the bus 540 which are coupled to a selection input of the multiplexer 640.

[0053] Referring to Figure 7 there is illustrated a top plan view of a first assembly orientation 700 including the cooking appliance 100 and cooking hob 400 in accordance with a preferred embodiment of the present invention. In this first assembly orientation 700 the first base rail BR1 abuts the first hob rail HR1, the second base rail BR2 abuts the second hob rail HR2, and the third base rail BR3 abuts the third hob rail HR3. Consequently, the identifier resistor Ri is across the first and second hob rails HR1, HR2 and the thermistor circuit IC is across the second and third hob rails HR2, HR3.

[0054] Referring to Figure 8 there is illustrated a schematic circuit diagram at specific terminals of the appliance decoder module 535 when the cooking appliance 100 and cooking bob 400 are in the first assembly orientation 700. As shown, the identifier resistor Ri couples output 0P2 to input IP1 and thermistor circuit IC couples output 0P2 to input 1P3. In this first assembly orientation 700, table 3 below (described later) can be used for identifying the profile of the cooking appliance 100.

[0055] Referring to Figure 9 there is illustrated a top plan view of a second assembly orientation 900 including the cooking appliance 100 and cooking hob 400 in accordance with a preferred embodiment of the present invention. In this second assembly orientation 900 the first base rail BR1 abuts the second hob rail HR2, the second base rail BR2 abuts the third hob rail HR3, and the third base rail BR3 abuts the first hob rail HR1. Consequently, the identifier resistor Ri is across the second and third hob rails HR2, HR3 and the thermistor circuit IC is across the first and third hob rails HR2, HR3.

[0056] Referring to Figure 10 there is illustrated a schematic circuit diagram at specific terminals of the appliance decoder module 535 when the cooking appliance 100 and cooking hob 400 are in the second assembly orientation 900. As shown, the identifier resistor Ri couples output 0P3 to input 1P2 and thermistor circuit IC couples output 0P3 to input IP1. In this second assembly orientation 900, table 4 below (described later) can be used for identifying the profile of the cooking appliance 100.

[0057] Referring to Figure 11 there is illustrated a top plan view of a third assembly orientation 1100 including the cooking appliance 100 and cooking hob 400 in accordance with a preferred embodiment of the present invention. In this third assembly orientation 1100 the first base rail BR1 abuts the third hob rail HR3, the second base rail BR2 abuts the first hob rail HR1, and the third base rail BR3 abuts the second hob rail HR2. Consequently, the identifier resistor Ri is across the first and third hob rails HR1, HR3 and the thermistor circuit TC is across the first and second hob rails HR1, HR2.

[0058] Referring to Figure 12 there is illustrated a schematic circuit diagram at specific terminals of the appliance decoder module 535 when the cooking appliance 100 and cooking hob 400 are in the third assembly orientation 1100. As shown, the identifier resistor RI couples output OPI to input 1P3 and thermistor circuit IC couples output aPi to input 1P2. In this third assembly orientation 1100, table 5 below (described later) can be used for identifying the profile of the cooking appliance 100.

[0059] From the above it will be apparent to a person skilled in the art that the decoder outputs OP1, OP and 0P3 are selectively coupled the electrically conductive hob rails HR1, HR2, HR3 and the decoder inputs lPi,1P2, 1P3 are also selectively coupled the electrically conductive hob rails HR1, HR2, HR3. In operation, the appliance decoder module 535 supplies a reference voltage Vref to a first one of the electrically conductive hob rails (HR1, HR2 or HR3). The resistor circuit or identifier resistor Ri in the cooking appliance 100, seated on the conductive hob rails (HR1, HR2 or HR3), modifies (attenuates) the reference voltage Vref to provide an appliance identification voltage Vid at a second one of the electrically conductive hob rails (HR1, HR2 or HR3). In operation, the appliance decoder module 535 also processes the appliance identification voltage Vid to determine a characteristic (cooking profile) of the cooking appliance seated on the conductive hob rails. Once the characteristic (cooking profile) is determined the cooking hob 400 can then send pulses to the inductive coil or coils 430 as determined by the characteristic (cooking profile).

[0060] With reference to the tables 3 to 5 stored in the memory module 515, each of the tables 3 to 5 have appliance orientation identification values that include: an output voltage value to be selectively provided to one of the hob rails HR1, HR2, HR3; and an appliance identification set of valid voltage ranges associated with respective cooking appliances from the set of cooking appliances io 100. These valid voltage ranges are based on the resistance values RV of table 2 when the input impedance of inputs IP1, 1P2 and 1P3 are each fixed at 5OKohms.

[0061] For example, in table 3 the set of valid voltage ranges are associated with the column labeled input IF1 and corresponds to expected voltage ranges at the input IP1 when output 0P2 is supplied with the output voltage value of 5 volts and outputs OH and 0P3 are floating. Thus, if under these conditions input IP1 receives a voltage of between 4.8 and 4.30 Volts then the cooking appliance 100 (cooking profile) is identified as a sous vide profile. As another example, if the IP1 receives a voltage of between 3.24 and 3.05 Volts then the cooking appliance 100 (cooking profile) is identified as a grill profile. In addition, there is an optional secondary valid voltage range associated with the respective cooking appliances 100 which in table 3 is input 1P3 that has a range of 0.15 to 2.5 volts. It is clear from the tables 3 to 5 that the identification set of valid voltage ranges cover a different voltage range ( 4.8 to 2.65) to that of the secondary valid voltage range of 0.15 to 2.5 Volts.

[0062] In table 4, the set of valid voltage ranges are associated with the column labeled input 1P2 and corresponds to expected voltage ranges at the input 1P2 when output 0P3 is supplied with the output voltage value of 5 volts and outputs OP1 and 0F2 are floating. Thus, if under these conditions input 1P2 receives a voltage of between 4.8 and 4.30 Volts then the cooking appliance 100 (cooking profile) is identified as a sous vide profile. As another example, if the 1F2 receives a voltage of between 3.24 and 3.05 Volts then the cooking appliance (cooking profile) is identified as a grill profile. Again, there is an optional secondary valid voltage range associated with the respective cooking appliances 100 which is input IP1 that has a range of 0.15 to 2.5 volts.

[0063] In table 5, the set of valid voltage ranges are associated with the column labeled input 1P3 and corresponds to expected voltage ranges at the input 1P3 when output OP1 is supplied with the output voltage value of 5 volts and outputs 0P2 and 0P3 are floating. Thus, if under these conditions input 1P3 receives a voltage of between 4.8 and 4.30 Volts then the cooking appliance 100 (cooking profile) is identified as a sous vide profile. As another example, if the 1P3 receives a voltage of between 3.24 and 3.05 Volts then the cooking appliance (cooking profile) is identified as a grill profile. Again, there is an optional secondary valid voltage range associated with the respective cooking appliances which is input 1P2 that has a range of 0.15 to 2.5 volts.

[0064] In table 6, the voltage to temperature conversion table illustrates sub-voltage ranges that are within the secondary valid voltage range. These sub-voltage ranges VR are based on the resistance values for the NTCT thermistor of table 1 when the thermistor circuit includes the NTCT in series with a 55KOhm resistor. Furthermore, these sub-voltage ranges VR are also based the input impedance of inputs IP1, 1P2 and 1P3 being each fixed at SoKohms and thus their cumulative voltage range correspond to the ranges shown for 1P3 of Table 3, IP1 of table 4, and 1P2 of table 5. As will be apparent to a person skilled in the art, each of the sub-voltage ranges VR relate to a temperature value of the thermistor circuit TC. Thus, for example, if the thermistor circuit is at 25 degrees Centigrade then one of the inputs IP1, 1P2, 1P3 will detect a voltage in the sub-range 1.14 to 1.37 Volts, whereas if the thermistor circuit is at 50 degrees Centigrade then one of the inputs IP1, 1P2, 1P3 will detect a voltage in the sub-range 1.74 to 1.82 Volts.

[0065] Referring to Figure 13 there is illustrated a flow diagram of a method 1300 for determining a cooking appliance characteristic in accordance with a preferred embodiment of the present invention. The method 1300 includes a start block 1310 which typically includes a switching on the cooking hob 400.

At a detecting block 1320 the cooking hob 400 detects if there is a cooking appliance 100 seated on the hob 400 and located in one of the appliance cooking regions 415. This detecting is performed by known circuitry and has not therefore been described in this specification. The method 1300, at a sending block 1330, performs a process of sending the reference voltage Vref to a first one of a plurality of electrically conductive hob rails supporting the cooking appliance 100 in the appliance cooking region 415.

[0066] The process of sending the reference voltage Vref includes the controller unit 505 reading one of the tables 3 to 5 stored in the memory module 515. In the first instance table 3 is read by the controller unit 505 after which the controller unit 505 sends control signals CS along the bus 540 to the relevant decoder module 535. The decoder module decodes the control signals CS to send an enable signal to the control input of the tn-state buffer 615 and disable signals to the control inputs of the tn-state buffer 610 and 620. Consequently, the reference voltage Vref of 5 Volts is sent or supplied to 0P2 from tn-state buffer 615 and outputs OP1 and 0P3 are floating.

[0067] The method 1300, at an attenuating block 1340, then performs attenuating the reference voltage Vref by the resistor circuit (identifier resistor Ri) mounted in the appliance 100 to provide the appliance identification voltage Vid at a second one of the electrically conductive hob rails which in this example is HR1. It should be noted that this attenuation will only generally occur when the appliance is orientated, with respect to the hob rails HR1, HR2, HR3, to match the characteristics of table 3.

[0068] The appliance identification voltage Vid is analogue to digital converted by the analogue to digital converter module 625, the 8 bit output digital code of which is sent to the controller unit 505 via the multiplexer 640. In this regard, the control signals CS on the bus 540 provide the required code to the select control input of the multiplexer 640 to thereby connect the output of the analogue to digital converter module 625 to the controller unit 505. There is then performed, at a processing block 1350, a processing of the appliance identification voltage Vid to determine the cooking appliance characteristic.

During the processing, the controller unit 505 reads a digitized voltage value DVV of the appliance identification voltage Vid received from the analogue to digital converter module 625. Then the set of valid voltage ranges of the column for input IP1 in table 3 are searched and compared with the digitized voltage value DVV to find a match.

[0069] At a test block 1360, a test is performed to determine if a match was found, and thus a cooking appliance characteristic identified. If there was no appliance characteristic identified a test block 1370 then determines if all of tables 3 to 5 have been read by the controller unit 505. Since only table 3 has been read, the method 1300 returns to the sending block 1330, and table 4 is then selected by the controller unit 505. The controller unit 505 then sends control signals CS along the bus 540 to the relevant decoder module 535. The decoder module decodes the control signals CS to send an enable signal to the control input of the tn-state buffer 620 and disable signals to the control inputs of the tn-state buffer 610 and 615. Consequently, the reference voltage Vref of 5 Volts is sent or supplied to 0P3 from tn-state buffer 620 and outputs Dpi and 0F2 are floating.

[0070] The method 1300, at the attenuating block 1340, then performs attenuating the reference voltage Vref by the resistor circuit (identifier resistor RI) mounted in the appliance 100 to provide the appliance identification voltage Vid at a second one of the electrically conductive hob rails which in this example is HR2. It should again be noted that this attenuation will generally only occur when the appliance is orientated, with respect to the hob rails HR1, HR2, HR3, to match the characteristics of table 4.

[0071] The appliance identification voltage Vid is analogue to digital converted by the analogue to digital converter module 630, the 8 bit output digital code of which is sent to the controller unit 505 via the multiplexer 640. In this regard, the control signals CS on the bus 540 provide the required code to the select control input of the multiplexer 640 to thereby connect the output of the analogue to digital converter module 630 to the controller unit 505. There is then performed, at a processing block 1350, a processing of the appliance identification voltage Vid to determine the cooking appliance characteristic.

During the processing, the controller unit 505 reads the digitized voltage value DVV of the appliance identification voltage Vid received from the analogue to digital converter module 630. Then the set of valid voltage ranges of the column for input 1P2 in table 4 are searched and compared with the digitized voltage value DVV to find a match.

[0072] At the test block 1360, a test is again performed to determine if a match was found, and thus a cooking appliance characteristic identified. If there was no appliance characteristic identified the test block 1370 then determines if all of tables 3 to 5 have been read by the controller unit 505. Since only tables 3 and 4 has been read, the method 1300 returns to the sending block 1330, and table 5 is then selected by the controller unit 505. The controller unit 505 then sends control signals CS along the bus 540 to the relevant decoder module 535.

The decoder module decodes the control signals CS to send an enable signal to the control input of the tn-state buffer 610 and disable signals to the control inputs of the tn-state buffer 615 and 620. Consequently, the reference voltage Vref of 5 Volts is sent or supplied to OH from tn-state buffer 610 and outputs 0P2 and 0P3 are floating.

[0073] The method 1300, at the attenuating block 1340, then performs attenuating the reference voltage Vref by the resistor circuit (identifier resistor Ri) mounted in the appliance 100 to provide the appliance identification voltage Vid at a second one of the electrically conductive hob rails which in this example is HR3. It should again be noted that this attenuation will generally only occur when the appliance is orientated, with respect to the hob rails HR1, HR2, HR3, to match the characteristics of table 5.

[0074] The appliance identification voltage Vid is analogue to digital converted by the analogue to digital converter module 635, the 8 bit output digital code of which is sent to the controller unit 505 via the multiplexer 640. In this regard, the control signals CS on the bus 540 provide the required code to the select control input of the multiplexer 640 to thereby connect the output of the analogue to digital converter module 635 to the controller unit 505. There is then performed, at a processing block 1350, a processing of the appliance identification voltage Vid to determine the cooking appliance characteristic.

During the processing, the controller unit 505 reads the digitized voltage value DVV of the appliance identification voltage Vid received from the analogue to digital converter module 635. Then the set of valid voltage ranges of the column for input 1P2 in table 5 are searched and compared with the digitized voltage value DVV to find a match.

[0075] At the test block 1360, a test is again performed to determine if a match was found, and thus a cooking appliance characteristic identified. If there was no appliance characteristic identified the test block 1370 then determines if all of tables 3 to 5 have been read by the controller unit 505. Since all the tables 3 to 5 have now been read the method 1300, at a block 1380, signals the user interface 535 that no match has been found. The user interface 535 thus provides a message on the visual display 520 to inform the user that manual appliance settings are required for the appliance placed on the appliance cooking region 415 and the method 1300 then terminates at an end block 1395.

[0076] Alternatively, if the test block 1360 identifies a match then the method 1300, at a controlling block 1390, performs a process of controlling heat supplied to the cooking appliance 100 on the appliance cooking region 415. The controlling is based a further process of attenuating the reference voltage Vref by the thermistor circuit Tc to provide a temperature dependent voltage at a third one of the electrically conductive hob rails (HR1,HR2,HR3). Thus, the process of controlling the heat is based on the temperature dependent voltage and the cooking appliance characteristic. As such, the controller unit 505 selectively sends the required control signals along the bus 540 to poll the relevant one of the analogue to digital converter modules 625, 630, 635 that has digitized the temperature dependent voltage provided by the thermistor circuit Tc. The controller unit 505 therefore compares digitized temperature dependent voltage with the voltages of table 6 to determine the temperature of the cooking appliance 100. Also, when bus 540 polls the relevant one of the analogue to digital converter modules 625, 630, 635, their resolution can be adjusted to be different to that of when the polled modules 625, 630, 635 are digitizing the appliance identification voltage Vid.

[0077] The controlling allows for the controller unit 505 to control the driver 530 which sends electromagnetic pulses to a selected one of the inductive coils 430 which thereby heats the cooking appliance 100 according to the cooking appliance characteristic (cooking profile). Detected changes in the temperature dependent voltage will thereby result in a corresponding adjustment of the power supplied to the inductive coils 430 and the clock 510 is used to determine the duration of temperature settings and when cooking is completed. After the cooking is completed the method 1300 terminates at the end block 1395.

[0078] Advantageously, the present invention allows for the characteristics and measured temperature of a cooking appliance 100 to be communicated to the cooking hob 400 without the need for radio transmitters. The present invention also can also determine the characteristics of cooking appliance 100 without the need for the requirement of a user aligning the appliance in a specific set orientation as will be apparent to a person skilled in the art.

OP1 0P2 0P3 IP1 1P2 1P3 PROFILE

VOLTS VOLTS VOLTS VOLTS VOLTS VOLTS

Z SV Z 4.80-4.30 X 0.15-2.5 SOUS VIDE Z SV Z 4.29-4.00 X 0.15-2.5 SLOW COOK Z SV Z 3.99-3.70 X 0.15-2.5 STEAMER Z 5V Z 3.69-3.45 X 0.15-2.5 SOUP Z SV Z 3.44-3.25 X 0.15-2.5 DEFROST Z SV Z 3.24-3.05 X 0.15-2.5 GRILL Z SV Z 3.04-2.85 X 0.15-2.5 FRIER Table 3, first valid cooking appliance orientation identification values.

OP1 0P2 OP3 P1 1P2 P3 PROFILE

VOLTS VOLTS VOLTS VOLTS VOLTS VOLTS

Z 7 5V 0.15-2.5 4.80-4.30 X SOUS VID[ 7 7 5V 0.15-2.5 4.29-4.00 X SLOW COOK Z 7 SV 0.15-2.5 3.99-3.70 X STEAMER 7 7 SV 0.15-2.5 3.69-3.45 X SOUP 7 7 5V 0.15-2.5 3.44-3.25 X DEFROST Z 7 SV 0.15-2.5 3.24-3.05 X GRILL 7 7 SV 0.15-2.5 3.04-2.85 X FRIER Table 4, second valid cooking appliance orientation identification values.

OPt 0P2 0P3 IP1 1P2 1P3 PROFILE

VOLTS VOLTS VOLTS VOLTS VOLTS VOLTS

SV Z Z X 0.15-2.5 4.80-4.30 SOUS VIDE SV Z Z X 0.15-2.5 4.29-4.00 SLOW COOK 5V Z Z X 0.15-2.5 3.99-3.70 STEAMER SV 7 7 X 0.15-2.5 3.69-3.45 SOUP 5V 7 7 X 0.15-2.5 3.44-3.25 D[FROST 5V Z Z X 0.15-2.5 3.24-3.05 GRILL SV 7 7 X 0.15-2.5 3.04-2.85 FRIER Table 5, third valid cooking appliance orientation identification values.

TEMPERATURE °C VOLTAGE (VOLTS) -25 0.15-0.21 ZERO 0.54-0.63 +25 1.14-1.37V +50 1.74-1.82 +75 2.05-2.11 +100 2.21-2.26 +125 2.29-2.32 +150 2.33-2.37 Table 6, voltage to temperature conversion table

Claims

Claims 1. A cooking appliance for use on a cooking hob, the appliance including: a cooking vessel; a base for seating the vessel on the cooking hob, the base including at least one electrically insulating mount; at least two spaced electrically conductive base rails mounted to the electrically insulating mount; and a resistance circuit electrically coupling the two spaced electrically conductive base rails.
2. The cooking appliance, as claimed in claim 1, wherein there are three said spaced electrically conductive base rails mounted to the electrically insulating mount, the base rails being a first, second and third base trail, and wherein the resistance circuit electrically couples the first base rail to the second base rail and a thermistor circuit electrically couples the second base rail to the third base rail.
3. The cooking appliance, as claimed in claim 1 or claim 2, wherein the base rails protrude from the electrically insulating mount.
4. The cooking appliance, as claimed in any preceding claim, wherein the base rails are of equal length.
5. The cooking appliance, as claimed in any preceding claim, wherein the base rails have an arcuate track profile when the base is viewed in a plan view.
6. The cooking appliance, as claimed in any preceding claim, wherein each of the base rails has an arcuate track profile of each of the base rails covers a circumference of approximately 120 degrees.
7. The cooking appliance, as claimed in claim 5 or claim 6, wherein the base rails are located adjacent an outer periphery of the electrically insulating mount.
8. The cooking appliance, as claimed in any preceding claim, wherein the resistance circuit is a single resistor.
9. The cooking appliance, as claimed in one of claims 2 to 8, wherein the thermistor circuit includes a resistor in series with a thermistor.
10. The cooking appliance, as claimed in one of claims 2 to 8, wherein the thermistor circuit is a thermistor coupled directly across the second rail and the third base rail.
11. The cooking appliance, as claimed in any preceding claim, further including a ferrous based inductive heating member forming part of the base.
12. The cooking appliance, as claimed in claim 10 or 11, wherein the thermistor is located proximal to the cooking vessel.
13. A set of cooking appliances, each of the appliances comprising the appliance as claimed in claims 1 to 12, wherein the resistance circuit uniquely identifies each of the appliances from the other appliances in the set.
14. A cooking hob including: a support with an outer support surface; spaced electrically conductive hob rails protruding from the outer support surface; at least one inductive coil; a driver having an output coupled to the inductive coil; a controller coupled to the driver; and an appliance decoder coupled to the controller, the appliance decoder having decoder outputs selectively coupled the electrically conductive hob rails and decoder inputs selectively coupled the electrically conductive hob rails.
15. The cooking hob as claimed in claim 14, wherein in operation the appliance decoder supplies a reference voltage to a first one of the electrically conductive hob rails and a resistor circuit in a cooking appliance seated on the conductive hob rails modifies the reference voltage to provide an appliance identification voltage at a second one of the electrically conductive hob rails.
16. The cooking hob as claimed in claim 15, wherein in operation the appliance decoder processes the appliance identification voltage to determine a characteristic of the cooking appliance seated on the conductive hob rails.
17. The cooking hob as claimed in claim 16, wherein the characteristic is a cooking profile of the cooking appliance seated on the conductive hob rails.
18. The cooking hob as claimed in claim 16 or 17, wherein there is a memory module coupled to the controller, wherein the memory module includes cooking appliance orientation identification values.
19. The cooking hob as claimed in claim 18, wherein the cooking appliance orientation identification values include an appliance identification set of valid voltage ranges associated with respective cooking appliances.
20. The cooking hob as claimed in claim 19, wherein the cooking appliance orientation identification values include a secondary valid voltage range associated with the respective cooking appliances.
21. The cooking hob as claimed in claim 20, wherein the appliance identification set of valid voltage ranges cover a different voltage range to that of the secondary valid voltage range.
22. The cooking hob as claimed in any one of claims 18 to 21, wherein the appliance identification values include an output voltage value to be selectively provided to one of the hob rails.
23. The cooking hob as claimed in any one of claims 14 to 22, wherein the hob rails are radially positioned relative to a central area.
24. The cooking hob as claimed in claim 23, wherein there are three hob rails that radially extend at an angle 120 of degrees from each other.
25. The cooking hob as claimed in any one of claims 14 to 24, wherein each of the decoder outputs is a tn-state output.
26. The cooking hob as claimed in claim 25, wherein the appliance decoder includes three outputs and three inputs, wherein each one of the outputs is an output from a tn-state buffer.
27. A method for determining a cooking appliance characteristic, the method including: method for determining a cooking appliance characteristic, the method being performed by a cooking hob and the method including: sending a reference voltage to a first one of a plurality of electrically conductive hob rails supporting a cooking appliance thereon; attenuating the reference voltage by a resistor circuit mounted in the appliance to provide an appliance identification voltage at a second one of the electrically conductive hob rails; and processing the appliance identification voltage to determine the cooking appliance characteristic.
28. The method for determining a cooking appliance characteristic as claimed in claim 27, wherein the sending is performed by a tn-state buffer.
29. The method for determining a cooking appliance characteristic as claimed in claim 27 or 28, wherein the processing includes comparing the appliance identification voltage with an appliance identification set of valid voltage ranges.
30. The method for determining a cooking appliance characteristic as claimed in any one of claims 27 to 29, wherein the method includes a further process of attenuating the reference voltage by a thermistor circuit mounted in the appliance to provide a temperature dependent voltage at a third one of the electrically conductive hob rails.
31. The method for determining a cooking appliance characteristic as claimed in any one of claims 27 to 30, including an additional process of controlling heat supplied to the appliance based on the temperature dependent voltage and the cooking appliance characteristic.
32. The method for determining a cooking appliance characteristic as claimed in any one of claims 27 to 31, wherein the method is performed by the cooking hob as claimed in any one of claims 14 to 26.
33. The method for determining a cooking appliance characteristic as claimed in any one of claims 27 to 32, wherein the cooking appliance is the cooking appliance as claimed in anyone of claims ito 13.
34. A cooking appliance substantially as described herein with reference to the accompanying drawings.
35. A cooking hob substantially as described herein with reference to the accompanying drawings.
36. A method substantially as described herein with reference to the accompanying drawings.