Control of a heater

Abstract

A haircare appliance comprising: a heater and processing circuitry configured to: detect a temperature of the heater; control a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, control a 5 power supplied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature, wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode. A haircare appliance operable in an active state and a dwell state is also described.

Description

1 P005492-W001CONTROL OF A HEATERBACKGROUND

[0001] Haircare appliances are generally used to treat or style hair.

[0002] Haircare appliances may include heaters, which may be heated to an operating temperature for the haircare appliance to treat or style the hair.SUMMARY

[0003] According to a first aspect, the present disclosure provides a haircare appliance comprising: a heater; and processing circuitry configured to control operation of the heater; wherein the haircare appliance is operable in a dwell state and operable in an active state; wherein the processing circuitry is configured to control the heater to maintain a dwell temperature in the dwell state; and wherein the processing circuitry is configured to control the heater to reach an operating temperature in the active state, wherein the operating temperature is greater than or equal to 70 degrees Celsius, and the dwell temperature is less than 70 degrees Celsius.

[0004] In this way, the haircare appliance is operable in a dwell state, with a dwell temperature at which the haircare appliance may be safer for the user to handle, and in an active state, with an operating temperature at which the haircare appliance may be used to style / treat the hair. For example, it may be safer for the user to wrap their hair around or insert their hair into the haircare appliance when the haircare appliance is in the dwell state.

[0005] Additionally, because the processing circuitry is configured to control the heater to maintain the dwell temperature in the dwell state (as opposed to switching the heater off in the dwell state, for example), the time required for the heater to heat up to the operating temperature when the haircare appliance is switched into the active state may be shorter.

[0006] It will be appreciated that the dwell temperature may be greater than room temperature. The dwell temperature may be at least 20°C, at least 30 °C, at least 40°C, or at least 50°C.

[0007] The dwell temperature may be a temperature which is safe for a user to touch. The dwell temperature may be no more than 65°C, or no more than 60°C.2 P005492-W001

[0008] In some examples, the dwell temperature may be 60°C. It will be appreciated that the dwell temperature being 60°C may comprise the dwell temperature being substantially 60°C (e.g., within an error of + / -10%).

[0009] In this way, the dwell temperature may be low enough for a user to safely handle the haircare appliance in the dwell state, and high enough to reduce the time required for the heater to heat up to the operating temperature when the haircare appliance is switched into the active state.

[0010] In some examples, the operating temperature may be high enough for the haircare appliance to style / treat the hair when the heater is at the operating temperature. In some examples, the operating temperature may be at least 90°C, at least 100°C, at least 110°C or at least 120°C.

[0011] In some examples, the haircare appliance may switchable between the dwell state and the active state. For example, the haircare appliance may be switchable from the dwell state to the active state, and vice versa.

[0012] In some examples, the haircare appliance may be switchable between the dwell state and the active state via a user input. The processing circuitry may be configured to receive a user input; and switch the haircare appliance from the dwell state into the active state (and / or vice versa) in response to receiving the user input. For example, the haircare appliance may comprise a user interface (e.g., a button) operable to provide the user input.

[0013] In this way, the user may have control over switching the haircare appliance between the dwell state and the active state.

[0014] In some examples, the haircare appliance may be switchable between the dwell state and the active state after a predetermined time period has elapsed. The processing circuitry may be configured to measure a time period (e.g., a time period in which the haircare appliance has been in the active state); and switch the haircare appliance from the active state into the dwell state in response to the measured time period reaching a threshold time period.

[0015] In this way, there may be a preset hair-styling period in which the haircare appliance is in the active state before it switches to the dwell state, which may improve the safety of the haircare appliance.3 P005492-W001

[0016] In some examples, the active state may comprise a plurality of phases (e.g., as described in further detail below). The haircare appliance may be switchable from the active state to the dwell state when the plurality of phases has been completed. The processing circuitry may be configured to: receive a completion signal indicating an end of a final phase in the plurality of phases; and, switch the haircare appliance from the active state into the dwell state in response to receiving the completion signal. For example, the completion signal may indicate that the time period in which the haircare appliance has been in the final phase has reached a threshold time period. As another example, the completion signal may indicate that the temperature of the heater has reached a predetermined temperature.

[0017] In this way, there may be a preset hair-styling period / cycle in which the haircare appliance is in the active state before it switches to the dwell state, which may improve the safety of the haircare appliance.

[0018] We will now describe some exemplary features of the haircare appliance, and an exemplary active state which includes a plurality of phases.

[0019] In some examples, the haircare appliance may be for styling the hair by applying steam to the hair.

[0020] In some examples, the haircare appliance may be formed of a haircare appliance body and a styling head (e.g., for styling hair). The styling head may correspond to a hair-styling attachment, which may be removably couplable to the haircare appliance body.

[0021] In some examples, the haircare appliance body may comprise the processing circuitry.

[0022] In some examples, the styling head may be in the form of a barrel.

[0023] In some examples, the styling head may comprise the heater. The heater may be a low thermal mass heater. In this way, the heater may heat up faster. In some examples, the haircare appliance (e.g., the styling head) may comprise a plurality of heaters. The plurality of heaters may be (e.g., evenly) distributed around a longitudinal axis of the styling head.

[0024] It will be appreciated that any of the features described with reference to a single heater may be applicable to one or more, or all of the heaters in the plurality of heaters. For example, the processing circuitry may be configured to control each4 P005492-W001 of the heaters, such that each of the heaters if maintained at the dwell temperature in the dwell state, and such that each of the heaters reaches the operating temperature in the active state.

[0025] In some examples, the heater may be configured / operable to heat a liquid to generate a vapour.

[0026] In some examples, the styling head (e.g., the barrel) may comprise an absorbent layer for retaining liquid. The absorbent layer may be disposed over a heater (or over the plurality of heaters). The heater may be operable to heat the absorbent layer to vaporise liquid retained by the absorbent layer. The styling head may comprise an exterior surface. The exterior surface may allow the vaporised liquid to be transmitted out of the styling head (e.g., the exterior surface may define perforations to allow vaporised liquid to be transmitted out of the styling head).

[0027] In this way, the styling head may enable the hair to be styled using steam.

[0028] In some examples, the heater, the absorbent layer, and / or the exterior surface may be configured to permit air within the styling head to flow through the respective heater, absorbent layer and / or exterior surface and out of the barrel. For example, the heater, the absorbent layer and / or the exterior surface may each define perforations (which may correspond to airflow outlets).

[0029] In this way, the styling head may allow an airflow out of the attachment, e.g., to style and / or dry the hair.

[0030] In some examples, the haircare appliance (e.g., the haircare appliance body) may comprise a reservoir for storing the liquid. In some examples, the haircare appliance body may comprise a liquid delivery arrangement operable to deliver (e.g. a predefined amount of) liquid from the reservoir to the styling head (e.g., to the absorbent layer). In some examples, the liquid delivery arrangement may comprise a pump.

[0031] In some examples, the haircare appliance body may comprise an airflow generator. The haircare appliance body may define one or more airflow inlets. The airflow generator may be operable to generate airflow out of the styling head (e.g., through the heater arrangement, the absorbent layer and / or the exterior surface). The haircare appliance may define one or more airflow paths, each airflow path extending5 P005492-W001 from a respective airflow inlet to a respective airflow outlet. The airflow generator may be operable to generate airflow along the one or more airflow paths.

[0032] In some examples the processing circuitry may be configured to operate the haircare appliance in a plurality of phases in the active state. The plurality of phases may together be referred to as a predefined styling procedure. The processing circuitry may be configured to initiate the predefined styling procedure in response to the haircare appliance switching into the active state. The plurality of phases may include a vapour generation phase. In some examples, in the vapour generation phase vapour is generated and emitted out of the styling head. In some examples in the vapour generation phase liquid is heated by the heater to generate a vapour. The vapour generation phase may include a wetting phase in which liquid is delivered from the reservoir to the absorbent layer (e.g., by operating the pump). The vapour generation phase may comprise a vaporisation phase (or a heating phase) in which the liquid retained by the absorbent layer is vaporised (e.g., by operating the heater). The plurality of phases may include an airflow generation phase in which airflow is generated by the airflow generator. Air may be emitted from the styling head during the airflow generation phase.

[0033] The processing circuitry may be configured to control the heater in each phase of the active state to reach and / or maintain a respective target temperature.

[0034] In some examples, the operating temperature may be a target temperature of the heater during the predefined styling procedure.

[0035] In some examples, the target temperature of the heater may be different for different phases of the active state. In some examples, the target temperature of the heater in a first phase of the plurality of phases (e.g., in the vapour generation phase, or in the vaporisation phase) may correspond to the operating temperature which is greater than or equal to 70 degrees, greater than or equal to 90°C, greater than or equal to 100°C, greater than or equal to 110°C or greater than or equal to 120°C.

[0036] In some examples, the operating temperature may depend on the hair-styling attachment which is coupled to the haircare appliance body.

[0037] It will be appreciated that the processing circuitry may be configured to control the heater: such that the temperature of the heater is maintained at the dwell temperature in the dwell state; and to control the heater such that the temperature of6 P005492-W001 the heater reaches the operating temperature in the active state. The processing circuitry may be configured to maintain the temperature of the heater at the operating temperature once the temperature of the heater reaches the operating temperature in the active state.

[0038] The dwell state may be a state in which the temperature of the heater is held / maintained at the dwell temperature. The temperature of the heater may be increased to the dwell temperature (e.g., from room temperature) in the dwell state. The active state may be a state in which the temperature of the heater is increased (e.g., from the dwell temperature) to the operating temperature, and in which the temperature of the heater is subsequently held / maintained at the operating temperature.

[0039] It will be appreciated that the processing circuitry may be configured to prevent power from being supplied to the airflow generator and / or to liquid delivery arrangement pump in the dwell state.

[0040] In some examples, the processing circuitry may be configured to control a power supplied to the heater such that the heater reaches and / or is maintained at the dwell temperature in the dwell state. The processing circuitry may be configured to control a power supplied to the heater such that the heater reaches the operating temperature in the active state; and / or to control a power supplied to the heater such that the heater is maintained at the operating temperature in the active state.

[0041] In some examples, the processing circuitry may be configured to receive a temperature signal indicative of the temperature of the heater. For example, the temperature signal may comprise a current measurement, a resistance measurement, a power measurement, or a temperature measurement. The processing circuitry may be configured to calculate a temperature of the heater from the temperature signal.

[0042] In some examples, the processing circuitry may be configured to use a temperature feedback loop to control the temperature of the heater. For example, the processing circuitry may be configured to use a temperature feedback loop to control the heater to maintain the dwell temperature, to reach the operating temperature, and / or to maintain the operating temperature.

[0043] The temperature feedback loop may comprise receiving the temperature signal. The temperature feedback loop may comprise calculating, using the7 P005492-W001 temperature signal (and e.g., the dwell temperature or the operating temperature), a power value to be supplied to the heater. The temperature feedback loop may comprise outputting the power value. The processing circuitry may be configured to control a power supplied to the heater based on the power value output by the temperature feedback loop.

[0044] For example, the temperature feedback loop may comprise a PI (a proportional-integral) controller.

[0045] In some examples, the heater may comprise a heater trace, which may be formed of copper. The heater may comprise a metal plate (e.g., an aluminium plate) over the heater trace. In some examples, the temperature signal may comprise a measurement of a parameter (e.g., a resistance, a current, a power, or a temperature) of the heater trace.

[0046] When the haircare appliance comprises a plurality of heaters, the temperature signal may be received for / from only one of the heaters.

[0047] The temperature signal from a single heater may be representative of the temperature of all the heaters. In this way, an accurate indication of the temperature of the heaters may be obtained, without measuring a temperature signal for all of the heaters.

[0048] In some examples, the processing circuitry may be configured to control the power supplied to the heater such that, when the haircare appliance is in the active state, a maximum power (e.g., the power rating of the heater, or the power rating of the haircare appliance) is supplied to the heater. For example, the processing circuitry may be configured to control the power supplied to the heater such that, when the haircare appliance is in the active state, the maximum power is supplied to the heater when the temperature of the heater is at the dwell temperature (e.g., to increase the temperature of the heater from the dwell temperature to the operating temperature). In some examples, the power rating of the heater, or the power rating of the haircare appliance may be 400W.

[0049] In this way, the speed at which the heater temperature rises from the dwell temperature to the operating temperature may be increased.

[0050] In examples in which the maximum power is supplied to the heater at the dwell temperature, it may be important to ensure that the power supplied to the heater8 P005492-W001 does not exceed the maximum power (e.g., the power rating of the heater) when the temperature of the heater is below the dwell temperature.

[0051] In some examples, the haircare appliance may be operable in a pre-heating mode (e.g., when the temperature of the heater is less than a threshold temperature), and in a primary heating mode (e.g., when the temperature of the heater is greater than or equal to the threshold temperature). A lower power may be supplied to the heater in the pre-heating mode than in the primary heating mode.

[0052] In some examples, the processing circuitry may be configured to: detect a temperature of the heater; control a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, control a power supplied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature, wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.

[0053] In some examples, the threshold temperature may be less than the dwell temperature. In some examples, the threshold temperature may be equal to the dwell temperature.

[0054] In this way, the power supplied to the heater may be reduced below the threshold temperature (and the dwell temperature), and prevented from exceeding the maximum power, or power rating of the heater, for example.

[0055] In some examples, the heater may comprise a first heating element and a second heating element. The first heating element and the second heating element may be connected in parallel with one another. In some examples, the lower power in the pre-heating mode may be achieved by turning on the first heating element and the second heating element in an alternating manner (or one at a time). The processing circuitry may be configured to: control the power supplied to the heater such that power is supplied the first heating element and the second heating element in an alternating manner in the pre-heating mode; and control the power supplied to the heater such that power is supplied to the first heating element and the second heating element simultaneously in the primary heating mode.

[0056] In this way, a lower power may be supplied to the heater in the pre-heating mode than in the primary heating mode. Additionally, the decrease in power with9 P005492-W001 increasing temperature may be smaller for a heater formed of two heating elements in parallel, as compared to a heater formed of a single heating element.

[0057] In some examples, the same input voltage may be applied to the heater in the pre-heating mode and in the primary heating mode. In some examples, the processing circuitry may be configured to: apply an input voltage across the first heating element and the second heating element in an alternating manner in the pre-heating mode; and apply the input voltage across the first heating element and the second heating element simultaneously in the primary heating mode.

[0058] In this way, control of the power supplied to the heater may require lower processing requirements.

[0059] In some examples, the first heating element and the second heating element may have the same resistance. The same resistance may be understood to mean substantially the same resistance.

[0060] In some examples, the processing circuitry may be configured to, in the preheating mode control the power supplied to the heater such that: power is supplied to the first heating element according to a first duty cycle; and power is supplied to the second heating element according to a second duty cycle; and, wherein the first duty cycle is the same as the second duty cycle.

[0061] In some examples, the first duty cycle and the second duty cycle may both be 50%. The processing circuitry may be configured to control power supplied to the heater such that power is supplied to the heater according to a total duty cycle in the pre-heating mode. The total duty cycle may be equal to the sum of the first duty cycle and the second duty cycle. The total duty cycle may be 100%.

[0062] In this way, the speed at which the temperature of the heater increases to the threshold temperature may be increased.

[0063] In some examples, total duty cycle may be less than 100%.

[0064] In some examples, the processing circuitry may be configured to control the power supplied to the heater such that a power of no more than 500W, or no more than 400W is supplied to the heater. The power rating of the heater and / or the power rating of the haircare appliance may be 500W or less, or 400W or less.

[0065] In this way, the cost of the heater and / or of other electronic components within the haircare appliance may be reduced.10 P005492-W001

[0066] In some examples, the processing circuitry may be configured to control power supplied to the heater such that a power equal to a power rating of the heater is supplied to the heater in the primary heating mode (e.g., when the temperature of the heater is at the threshold temperature).

[0067] In this way, the speed at which the heater temperature rises to the operating temperature may be increased in the primary heating mode.

[0068] In some examples, the processing circuitry may be configured to control the power supplied to the heater such that a power supplied to the heater remains below the power rating of the heater in the pre-heating mode. In some examples, the processing circuitry may be configured to control the power supplied to the heater such that: the highest power supplied to the heater in the pre-heating mode is lower than the highest power supplied to the heater in the primary heating mode (e.g., the maximum power).

[0069] It will be appreciated that a power of a given magnitude (e.g., the maximum power, the power rating and / or 400W) being supplied to the heater may be due to a voltage of a given magnitude being applied to the heater, and due to the resistance of the heater. A maximum power being supplied to the heater may comprise a maximum voltage being supplied to the heater, and / or the heater having a minimum resistance.

[0070] According to a second aspect of the disclosure, there is provided a computer- implemented method for controlling a heater of a haircare appliance, the haircare appliance being operable between an active state and a dwell state; wherein the computer-implemented method comprises: controlling the heater to maintain a dwell temperature when the haircare appliance is in the dwell state; and, controlling the heater to reach an operating temperature when the haircare appliance is in the active state; wherein the operating temperature is greater than or equal to 70 degrees Celsius, and the dwell temperature is less than 70 degrees Celsius.

[0071] It will be appreciated that any of the features described with reference to the first aspect may be applied equally to the second aspect.

[0072] For example, the computer-implemented method may comprise controlling a power supplied to the heater to maintain the dwell temperature when the haircare appliance is in the dwell state; and / or controlling a power supplied to the heater such that the heater.11 P005492-W001

[0073] According to a third aspect of the disclosure, there is provided a haircare appliance comprising: a heater and processing circuitry configured to: detect a temperature of the heater; control a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, control a power supplied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature, wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.

[0074] In this way, the power supplied to the heater may be lower when the temperature of the heater is below the threshold temperature. This may inhibit the power supplied to the heater from exceeding the power rating of the heater, and / or the power rating of the haircare appliance in the pre-heating mode. The heater may be heated up in a slower and / or more controlled manner when the temperature of the heater is below the threshold temperature. The heater may be heated up more rapidly once the temperature of the heater reaches the threshold temperature.

[0075] The processing circuitry may be configured to switch the haircare appliance from the pre-heating mode into the primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature.

[0076] The pre-heating mode may be a mode in which the temperature of the heater is increased to the threshold temperature (e.g., from room temperature). The haircare appliance may enter into the pre-heating mode when the haircare appliance (or the heater) is first switched on. The primary heating mode may be a mode in which the temperature of the heater is increased from the threshold temperature (e.g., to an operating temperature).

[0077] In some examples, the processing circuitry may be configured to control the power supplied to the heater such that: the largest power supplied to the heater in the pre-heating mode is lower than the largest power supplied to the heater in the primary heating mode.

[0078] In some examples, the processing circuitry may be configured to control power supplied to the heater such that a power equal to a power rating of the heater is supplied to the heater in the primary heating mode. The highest power supplied to the heater in the primary heating mode may be equal to the power rating of the heater.12 P005492-W001In some examples, the processing circuitry may be configured to control the power supplied to the heater such that a power supplied to the heater remains below the power rating of the heater in the pre-heating mode.

[0079] In this way, the speed at which the heater temperature rises from the threshold temperature (e.g., to the operating temperature) may be increased in the primary heating mode. Additionally, the heater may be prevented from exceeding the power rating of the heater in the pre-heating mode.

[0080] In some examples, the heater may comprise a first heating element and a second heating element. The first heating element and the second heating element may be connected in parallel with one another. In some examples, the lower power in the pre-heating mode may be achieved by turning on the first heating element and the second heating element in an alternating manner (or one at a time). The processing circuitry may be configured to: control the power supplied to the heater such that power is supplied the first heating element and the second heating element in an alternating manner in the pre-heating mode; and control the power supplied to the heater such that power is supplied to the first heating element and the second heating element simultaneously in the primary heating mode.

[0081] In this way, a lower power may be supplied to the heater in the pre-heating mode than the power supplied in the primary heating mode.

[0082] In some examples, the same input voltage may be applied to the heater in the pre-heating mode and in the primary heating mode. In some examples, the processing circuitry may be configured to: apply an input voltage across the first heating element and the second heating element in an alternating manner in the pre-heating mode; and apply the input voltage across the first heating element and the second heating element simultaneously in the primary heating mode.

[0083] In this way, control of the power supplied to the heater may require fewer processing requirements.

[0084] In some examples, the first heating element and the second heating element may have the same resistance. The same resistance may be understood to mean substantially the same resistance.

[0085] In some examples, the processing circuitry may be configured to, in the preheating mode control the power supplied to the heater such that: power is supplied13 P005492-W001 to the first heating element according to a first duty cycle; and power is supplied to the second heating element according to a second duty cycle; and, wherein the first duty cycle is the same as the second duty cycle.

[0086] In some examples, the first duty cycle and the second duty cycle may both be 50%. The processing circuitry may be configured to control power supplied to the heater such that power is supplied to the heater according to a total duty cycle in the pre-heating mode. The total duty cycle may be equal to the sum of the first duty cycle and the second duty cycle. The total duty cycle may be 100%.

[0087] In this way, the speed at which the temperature of the heater increases to the threshold temperature may be increased.

[0088] In some examples, total duty cycle may be less than 100%.

[0089] In some examples, the processing circuitry may be configured to control the power supplied to the heater such that a power of no more than 500W, or no more than 400W is supplied to the heater. The power rating of the heater and / or the power rating of the haircare appliance may be 500W or less, or 400W or less.

[0090] In this way, the cost of the heater and / or of other electronic components within the haircare appliance may be reduced.[0091 In some examples, the processing circuitry may be configured to control the power supplied to the heater such that, a maximum power (e.g., the power rating of the heater, or the power rating of the haircare appliance) is supplied to the heater when the temperature of the heater is at the threshold temperature (e.g., to increase the temperature of the heater from the threshold temperature to the operating temperature).

[0092] In this way, the speed at which the heater temperature increases from the threshold temperature to the operating temperature may be increased.

[0093] In some examples, the haircare appliance may be operable in a dwell state and in an active state. The processing circuitry may be configured to: control the heater to reach an operating temperature when the haircare appliance is in the active state; and control the heater to maintain a dwell temperature when the haircare appliance is in the dwell state. The operating temperature may be greater than or equal to 70 degrees Celsius, and the dwell temperature may be less than 70 degrees Celsius.14 P005492-W001

[0094] In this way, the haircare appliance is operable in a dwell state, with a dwell temperature at which the haircare appliance may be safer for the user to handle, and in an active state, with an operating temperature at which the haircare appliance may be used to style / treat the hair. Additionally, the time which it takes for the temperature to heat up to the operating temperature when the haircare appliance is switched into the active state from the dwell state may be shorter.

[0095] In some examples, the threshold temperature may be less than or equal to the dwell temperature.

[0096] In this way, the power supplied to the heater may be reduced below the dwell temperature and prevented from exceeding the maximum power, or power rating of the heater, for example. Additionally, the heater may be heated up more quickly from the dwell temperature to the operating temperature.

[0097] In some examples, the haircare appliance may comprise a plurality of heaters. It will be appreciated that any of the features described with reference to a single heater may be applicable to one or more, or all of the heaters in the plurality of heaters.

[0098] In some examples, detecting the temperature may comprise receiving a temperature signal indicative of the temperature of the heater. For example, the temperature signal may comprise a current measurement, a resistance measurement, a power measurement, or a temperature measurement. Detecting the temperature may comprise calculating the temperature from the temperature signal.

[0099] When the haircare appliance comprises a plurality of heaters, the temperature signal may be received for / from only one of the heaters.

[0100] In some examples, the haircare appliance may be for styling the hair by applying steam to the hair.

[0101] In some examples, the haircare appliance may be operable in a plurality of phases (e.g., a vapour generation phase and an airflow generation phase). The processing circuitry may be configured to control the power supplied to the heater such that the temperature of the heater reaches and / or is maintained at a respective operating temperature when the haircare appliance is in one of the plurality of phases. The operating temperature may be different for each of the different phases.15 P005492-W001

[0102] For each of the phases, the operating temperature may be greater than the threshold temperature. Therefore, when the haircare appliance is in one of the phases, the haircare appliance may be in the primary heating mode.

[0103] It will be appreciated that any of the features described with reference to the first aspect may be equally applied to the third aspect of the disclosure, and vice versa.

[0104] According to a fourth aspect of the disclosure, there is provided a computer- implemented method for controlling a power applied to a heater of a haircare appliance, the computer-implemented method comprising: detecting a temperature of the heater; controlling a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, controlling a power applied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature; wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.

[0105] It will be appreciated that any of the features described with reference to the third aspect may be equally applied to the fourth aspect of the disclosure.

[0106] According to a fifth aspect of the disclosure, there is provided a computer programme product comprising instructions which, when executed by the computer cause the computer to carry out the steps of the computer-implemented method of the second aspect or of the fourth aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0107] Figure 1 shows an example of a haircare appliance.

[0108] Figure 2 shows a flow diagram of a predefined styling procedure.

[0109] Figure 3 shows a flow diagram of an operation of a haircare appliance.

[0110] Figure 4 shows a plot of power and resistance against temperature.

[0111] Figure 5 shows a plot of power and resistance against temperature.

[0112] Figure 6 shows a flow diagram of an operation of a haircare appliance.

[0113] Figure 7 shows a plot of power and resistance against temperature.

[0114] Figure 8 shows plots of power draw over time for a heater (left hand side) and for individual heating elements of the heater (right hand side).16 P005492-W001DETAILED DESCRIPTION

[0115] Figure 1 shows an example haircare appliance 100. The haircare appliance 100 comprises a hair-styling attachment in the form of barrel 102, a haircare appliance haircare appliance body 104 and an electrical cable 106 extending from the haircare appliance body 104, for supplying electrical power to electrical components of the haircare appliance 100. The electrical cable 106 comprises a plug (not shown in Figure 1) at a distal end of the cable 106 with respect to the haircare appliance body 104, which can be plugged into a socket in order to supply mains 10 power to the haircare appliance 100.

[0116] The haircare appliance body 104 includes airflow inlets 108, a reservoir 110, an airflow generator 112, a start button 113, processing circuitry 114, a pump 116 and liquid outlets 118, 120. The haircare appliance body 104 has a generally hollow tubular housing formed of plastic. The reservoir 110, the airflow generator 112, the processing circuitry 114, the pump 116 and the liquid outlets 118, 120 are within the tubular housing of the haircare appliance body 104. A central longitudinal axis of the haircare appliance body 104 coincides with a central longitudinal axis of the haircare appliance 100. The airflow inlets 108 are each generally circular perforations in a side wall of the tubular housing of the haircare appliance body 104. The airflow inlets 108 are arranged in an irregular pattern in the side wall. However, in other examples, the airflow inlets may be arranged in evenly distributed longitudinal rows along a part of a length of the side wall and in evenly distributed circumferential rows around a circumference of the side wall.

[0117] The reservoir 110 is for storing liquid (in this case, water), which is delivered to the barrel 102 by the pump 116. The reservoir 110 in this case is an integrated water tank, which may be removable from the haircare appliance 100, for example to top up the reservoir 110 with additional liquid or to clean the reservoir 110.

[0118] The haircare appliance 100 comprises a reservoir sensor 111, which in Figure 1 is arranged in the haircare appliance body 104 and is coupled to the processing circuitry 114. The reservoir sensor I l l is configured to sense whether the reservoir 110 is connected to the haircare appliance 100. The reservoir sensor 111 may be a17 P005492-W001 mechanical switch, a Hall effect sensor paired to a magnet on the reservoir 110 or a radio frequency identification (RFID) sensor to sense the presence of the reservoir 110. The haircare appliance 100 of Figure 1 is operable to deliver a predefined amount of the liquid from the reservoir 110 to the barrel 102 in dependence on the reservoir sensor 111 sensing that the reservoir 110 is connected to the haircare appliance 100. For example, the predefined amount of the liquid may be delivered in response to input from a user (e.g. in response to a user initiating a predefined styling procedure or wetting of the absorbent layer), provided that the reservoir sensor 111 senses that the reservoir 110 is connected to the haircare appliance 100.

[0119] The reservoir 110 is fluidly connected to the pump 116 by pipes 122 extending longitudinally within the tubular housing of the haircare appliance body 104. The pump 116 delivers water from the reservoir 110 to the barrel 102 via the liquid outlets 118, 120 of the haircare appliance body 104.

[0120] The airflow generator 112 includes a motor 124 and an impeller 126 and may be considered 20 to be an air blower for blowing air into the barrel 102. The motor 124 is attached to the impeller 126 and is operable to rotate the impeller 126 when switched to an on state, e.g. by the processing circuitry 114. The impeller 126 is operable to generate an airflow from the airflow inlets 108 and into the barrel 102. In Figure 1, the airflow enters the barrel 102 through an airflow outlet 128 of the haircare appliance body 104, which is fluidly connected to a channel 130 within the barrel 102. The airflow outlet 128 is defined by circular perforations at an end of the tubular housing of the haircare appliance body 104. In other cases, though, the airflow generated by the airflow generator 112 may enter a different region of the barrel 102 and / or via a different outlet or outlets than the airflow outlet 128 of the haircare appliance body 104.

[0121] The barrel 102 comprises a heater 132, an absorbent layer 134 for retaining a liquid (in this case, the liquid delivered from the reservoir 110), and a cover layer 136. The heater 132 has a generally hollow tubular shape. An interior hollow chamber of the heater 132 defines the channel 130 within the barrel 102. The absorbent layer 134 is disposed over the heater 132 and the cover layer 136 is disposed over the absorbent layer 134, so that the cover layer 136 overlaps the absorbent layer 134 and the heater 132, and the absorbent layer 134 overlaps the18 P005492-W001 heater 132. The absorbent layer 134 is disposed between the cover layer 136 and the heater 132. The absorbent layer 134 and the cover layer 136 each have a generally hollow tubular shape. A cross-sectional area of the absorbent layer 134 is larger than that of the heater 132 but smaller than that of the cover layer 136. The heater 132, the absorbent layer 134 and the cover layer 136 are concentric, and each extend along the central longitudinal axis of the haircare appliance 100 (and of the barrel 102). In Figure 1, an exterior surface 135 of the barrel 102 corresponds to an exterior surface of the cover layer 136. In use, a tress of hair is wrapped around the exterior surface of the barrel 102 to style the tress.

[0122] The heater 132 is operable to heat the absorbent layer 134 to vaporise the liquid retained by the absorbent layer 134 to generate a vapour. The vapour generated by vaporising the liquid 15 retained by the absorbent layer 134 is transmitted through the exterior surface 135 of the barrel (in this case, through the cover layer 136) and out of the haircare appliance 100, in use. The exterior surface 135 of the barrel 102 is thus permeable by the airflow and the vapour. The heater 132 may also be used for heating an airflow generated by the airflow generator 112, in addition to heating the absorbent layer 134 to generate the vapour.

[0123] The heater 132 is a so-called low thermal mass heater, which can be heated and cooled relatively rapidly. In this case, the heater 132 is configured to be heated from an off state to a temperature of at least 100 degrees Celsius in less than 5 seconds. A heater temperature of at least 100 degrees Celsius is generally high enough to begin vaporising the liquid retained by the absorbent layer 134. In the off state in this example, the processing circuitry 114 does not supply electrical power to the heater 132, so the heater 132 remains at room temperature. The heater 132 is also configured to be heated from a temperature of 60 degrees Celsius to a temperature of at least 100 degrees Celsius in less than 2 seconds. The temperature of 60 degrees Celsius for example corresponds to a dwell temperature, which may be low enough 30 that a user can handle the haircare appliance 100 to some extent without burning themselves but which is high enough to reduce the time to begin vaporisation of the liquid. The heater 132 has a thickness of less than 0.6 millimetres in a plane perpendicular to a longitudinal axis of the barrel 102, allowing it to be heated and cooled relatively rapidly.19 P005492-W001

[0124] In Figure 1, the pump 116 is configured to deliver a predefined amount of the liquid (in this case, a dose of water) from the reservoir 110 to the absorbent layer 134. For example, the predefined amount of the liquid may be selected to generate a desired amount of vapour to achieve a particular style without overly wetting the hair and increasing a time taken to dry the hair and set the style. For an average tress of hair, the amount of liquid to achieve effective styling results tends to be between around 0.5g and 1g. To deliver the predefined amount of the liquid, the pump 116 may be configured to pump the liquid at a predefined rate for a predefined amount of time to deliver the predefined amount of the liquid from the reservoir 110 to the absorbent layer 134. The predefined amount of the liquid may be delivered as part of a predefined styling procedure, for example during a wetting phase which is performed before a vaporisation phase, as discussed in more detail with reference to Figure 2.

[0125] The pump 116, the pipes 122 to deliver liquid to the pump 116 from the reservoir 110, and at least one conduit (not shown in Figure 1) to deliver the predefined amount of liquid from the pump 116 to the absorbent layer 134 may be considered to form a liquid delivery arrangement. In some cases, though, the pump 116 may be directly connected to the reservoir 110 rather than being indirectly connected to the reservoir 110 via the pipes 122 or another conduit. The reservoir 110, the liquid delivery arrangement, the heater 132 and the absorbent layer 134 may together be considered to be a vapour generation system.

[0126] The absorbent layer 134 absorbs the liquid (in this case, water) delivered by the liquid delivery arrangement. The absorbent layer 134 of Figure 1 comprises a wicking material, which distributes the water throughout the absorbent layer 134 due to a capillary effect. The water absorbent material of the absorbent layer 134 is layered on top of the heater 132. The heater 132 can be heated relatively rapidly, which, in turn, can rapidly heat the wet absorbent layer 134 on the heater 132 to generate steam. This allows steam to be generated close to a surface of the barrel 102 (which corresponds to an exterior, e.g. outer, surface of the cover layer 136, which is opposite to an interior, e.g. inner, surface of the cover layer 136 facing the absorbent layer 134). In Figure 1, there is a gap between the absorbent layer 134 and the heater 132. However, in other examples, the absorbent layer 134 may be in20 P005492-W001 contact with the heater 132 to allow steam to be generated more efficiently upon heating the heater 132. A material for the absorbent layer 134 may be selected for the absorbent layer 134 to receive the liquid and distribute the liquid across the absorbent layer 134 relatively evenly, to withstand the temperatures generated by the heater 132 in generating the vapour, and to be sufficiently thin to permit thermal energy generated by the heater 132 to be transferred to hair of a user (which is wrapped around an outer surface of the barrel 102, in use). In Figure 1, the absorbent layer 134 is formed of a microfibre material, such as a mix of polyester with polyamide. For a single-ply woven layer of polyester with polyamide, a suitable thickness of the absorbent layer 134 is around 500 micrometres, with a fibre diameter of around 10 micrometres.

[0127] The absorbent layer 134 of Figure 1 is removeable from the haircare appliance 100 by removing the cover layer 136 overlying the absorbent layer 134 and then removing the absorbent layer 134 (or by removing the cover layer 136 and the absorbent layer 134 together). For example, a clip or other locking mechanism may be disengaged to allow the cover layer 136 and / or the absorbent layer 134 to be moved relative to other components of the haircare appliance 100. The cover layer 136 and / or the absorbent layer 134 may then be 20 slid in a direction parallel to the central longitudinal axis of the haircare appliance 100, away from the haircare appliance body 104, so as to disconnect the cover layer 136 and the absorbent layer 134 from the barrel 102. In another example, the absorbent layer 134 and the cover layer 136 may be wrapped around the heater 132 and fixed to a particular location along the barrel 102 by a fixture to enable appropriate tensioning of the absorbent layer 134 and improve thermal contact between the absorbent layer 134 and the heater 132. In this example, the fixture can be disengaged to allow the absorbent layer 134 and the cover layer 136 to be unwrapped from the barrel 102 and removed from the haircare appliance 100.

[0128] The cover layer 136 is a metallic mesh structure layered on top of the absorbent layer 134 in 30 Figure 1. In Figure 1, there is a gap between the cover layer 136 and the absorbent layer 134. However, in other examples, the cover layer 136 may be in contact with the absorbent layer 134. The cover layer 136 of Figure 1 is formed of stainless steel 316, with a plain weave structure. For a single-ply cover21 P005492-W001 layer 136 with this structure, a suitable thickness is around 50 micrometres, with a wire diameter of around 25 micrometres, an open area between adjacent wires of around 40 micrometres and a total open area of around 40%. In general, a diameter of a perforation of the cover layer 136 (e.g. corresponding an open area between 5 adjacent fibres for a mesh structure) may be less than around 70 micrometres to limit snagging of hair on the cover layer 136, as the diameter of a relatively fine hair is typically around 70 micrometres.

[0129] The heater 132, the absorbent layer 134 and the cover layer 136 are configured to permit air 10 within the barrel 102 (such as the air within the channel 130, generated by the airflow generator 112) to flow out of the barrel 102, through the heater 132, the absorbent layer 134 and the cover layer 136. In the example of Figure 1, the heater 132, the absorbent layer 134 and the cover layer 136 each comprise perforations for the air to flow through (which may be referred to as first, second and third perforations, respectively).

[0130] In the example of Figure 1, the perforations in the heater 132 correspond to through-holes in the material of the heater 132. For example, the heater 132 may be a perforated shim. The perforations in an absorbent layer such as the absorbent layer 134 of Figure 1 may also be through-holes, like those of the heater 132, which may align with at least one of the perforations in the heater 132 and / or the cover layer 136. However, in Figure 1, the perforations in the absorbent layer 134 correspond to pores in a porous microfibre material. The mesh structure of the cover layer 136 of Figure 1 has gaps between adjacent strands that are woven or otherwise connected together to form the mesh. These gaps form the perforations in the cover layer 136, which allow air to flow through. In other cases, though, 25 the cover layer 136 may also or instead have through-holes, which may align with at least one of the perforations in the heater 132 and / or the absorbent layer 134.

[0131] In addition to being permeable to air, the cover layer 136 is also permeable to the vapour generated by vaporising the liquid retained by the absorbent layer 134. The vapour can pass 30 out of the barrel 102 through the cover layer 136 via the perforations in the cover layer 136, such as via the open areas in a mesh structure of the cover layer 136. The vapour generated by the haircare appliance 100 is delivered to the hair wrapped around the barrel 102, in use, to generate a desired style (such as22 P005492-W001 a curl or wave in the hair). After the liquid has been vaporised from the absorbent layer 134, the haircare appliance 100 can be operated to deliver airflow generated by the airflow generator 112 to the hair, through the 5eater 132, the absorbent layer 134 and the cover layer 136. If the heater 132 is an on state during airflow generation (e.g. so that electrical power is being supplied to the heater 132 so as to heat the heater 132 above room temperature), the heater 132 can heat the airflow passing through the heater 132, so that the airflow delivered to the hair, through the cover layer 136, is a heated airflow for drying the hair. Subsequently, the heater 132 can be turned off. Styling may cease at this point, in which case the airflow may also be turned off. However, in other examples, the airflow may remain on so as to deliver a cooling airflow to the hair, through the cover layer 136, to set the style.

[0132] The haircare appliance 100 of Figure 1 includes a power sensor 139 for obtaining a power signal indicative of a power consumed by the heater 132. The haircare appliance includes a barrel temperature sensor 140 to sense a temperature at a surface of the barrel 102 (in this case, corresponding to a temperature at a surface of the cover layer 136). A respective output of the power sensor 139 and / or the barrel temperature sensor 140 may be used by the processing circuitry 114 to aid control of the haircare appliance 100, for example to perform a predefined styling procedure as described further with reference to Figure 2.

[0133] The haircare appliance 100 of Figure 1 may be configured to provide a predefined amount of liquid of between 0.5 grams (g) and 1.5g, depending on a size of the barrel 102, and to 30 spread the liquid relatively evenly to the absorbent layer 132 within a few seconds, such as in less than 4 seconds. For example, the haircare appliance 100 may be operated to evaporate liquid at a rate of around 3 grams per minute. This means that a typical liquid dose of 0.0.5g will be evaporated by the heat applied to the absorbent layer 134 by the heater 132 in around 10 seconds. A heated airflow, at a temperature of around 95 degrees Celsius or more, may be achieved for up to 10 seconds, and a temperature at a surface of the barrel 102 may be lowered to less than around 75 degrees Celsius in 5 seconds or less.

[0134] Operation of the airflow generator 112 and the pump 116 is controlled by the processing circuitry 114, which is electrically connected to the motor 124 of the airflow generator 112 and to the pump 116. The processing circuitry 114 is23 P005492-W001 configured to control the haircare appliance 100 to perform a predefined styling procedure, as discussed in more detail with reference to Figure 2. The predefined styling procedure may be used to perform surface steam curling of hair of a user of the haircare appliance 100.

[0135] The processing circuitry 114 in Figure 1 is configured to control the haircare appliance 100 to perform the predefined styling procedure. The processing circuitry 114 may implement storage, at least one data interface for transferring data to another component and / or receiving data from another component, such as a sensor of the haircare appliance 100, e.g. the power sensor 139, the barrel temperature sensor 140 and / or another sensor of the haircare appliance 100. The circuitry may also implement 20 a bus to allow communication between the various internal components of the processing circuitry 114. The processing circuitry 114 may receive data from a sensor, which may be referred to as sensor data and may be in the form of at least one signal from the sensor, via the at least one data interface. The sensor data may be stored in the storage and processed using the processor for example based on instructions stored within the storage defining processing to be performed by the processing circuitry 114, such as instructions to implement the predefined styling procedure. The processor may generate at least one configuration signal for configuring component(s) of the haircare appliance 100, based on the instructions. For example, the processor may generate a configuration signal to send to the airflow generator 112 to control a configuration of the airflow generator 112, e.g. to switch the airflow 30 generator 112 from an off state to an on state or vice versa and / or to adjust a parameter, such as a flow rate, of the airflow generated by the airflow generator 112. The processor may also or instead generate a configuration signal to send to a heater 132 of the barrel 102 to control a configuration of the heater 132, e.g. to switch the heater 132 from an off state to an on state or vice versa and / or to adjust a parameter, such as a set temperature or power, of the heater 132. In this way, the processing circuitry 114 can adjust a configuration of components of the haircare appliance 100 over time, in order to achieve the predefined styling procedure.

[0136] In Figure 1, the predefined styling procedure may be initiated by a user pressing the start button 113. Pressing the start button 113 generates a control signal24 P005492-W001(which in this case is an initiation signal to indicate that the predefined styling procedure is to be initiated). The start button 113 is an example of a mechanical user interface for receiving a control signal (in this, a mechanical control signal representing whether the start button 113 is depressed or not). In other examples, though, a haircare appliance otherwise similar to the haircare appliance 100 of Figure 1 may also or instead include a user interface of different type than the start button 113 (which may be mechanical in nature, such as a slider, or may be an electronic user interface, such as a touchscreen).

[0137] The user can also use an interface of the haircare appliance 100 to control various parameters of the predefined styling procedure, such as a duration of at least one phase of the predefined styling procedure, a quantity of the vapour, and a temperature of the barrel 102 for at least one phase of the predefined styling procedure. This allows for customisation of the predefined styling procedure for different hair types and desired styles. For example, the user may use a user interface of the haircare appliance 100 (e.g. a touchscreen, a button or other switch, or a slider) or an app on an electronic user device to select a desired value for at least one parameter of the predefined styling procedure. For example, a user may adjust the predefined styling procedure using a mode button of the haircare appliance 100 (not shown in Figure 1) to adjust the at least one parameter so as to change a style achieved (such as a curl tightness) and / or a thermal comfort of the user. The desired value(s) of the at least one parameter may be represented by customisation data instructing customisation of at least one parameter to be used for the predefined styling procedure. In these cases, the processing circuitry 114 receives the customisation data, e.g. from the user interface and / or from a network interface, and controls operation of the haircare appliance 100 to perform the predefined styling procedure based on the customisation data.

[0138] Figure 2 is a flow diagram 1700 of a predefined styling procedure according to an example, which may be implemented by a haircare appliance 100 in accordance with examples herein. In this example, the predefined styling procedure is an automated process comprising multiple phases which are controlled automatically by a processing circuitry 114 of the haircare appliance 100 after the predefined25 P005492-W001 styling procedure is initiated (as indicated by a start box 1702 in the flow diagram 1700).

[0139] To use the predefined styling procedure of the flow diagram 1700, hair is first wrapped around a barrel 102 of the haircare appliance 100. The hair is wrapped manually around the barrel 102.

[0140] The predefined styling procedure is started 1702 for example via a suitable interface such as the start button 113.

[0141] After initiation of the predefined styling procedure, a vapour generation phase1704 of the predefined styling procedure is performed. In the vapour generation phase 1704, the haircare appliance 100 is configured, by the processing circuitry 114, to generate a vapour, using the vapour generation system, and to emit the vapour out of the haircare appliance 100 through outlets of the barrel 102.

[0142] The vapour generation phase 1704 may begin with a wetting phase, in which the liquid (e.g. a predefined amount of the liquid) is delivered from the reservoir 110 to the absorbent layer 134, via the liquid delivery arrangement.

[0143] The haircare appliance 100 may comprise a sensor, such as a liquid detection system, to detect the amount of the liquid delivered to the absorbent layer 134. The liquid detection system may generate a liquid retention signal indicative of an amount of the liquid retained by the absorbent layer 134, in addition to or instead of the liquid detection signal discussed above. The liquid retention signal may be sent to the processing circuitry 114 and used by the processing circuitry 114 to adjust a respective length of at least one phase of the predefined styling procedure to account for variations in the amount of liquid delivered to the absorbent layer 134, e.g. so that the liquid is substantially fully evaporated during the vapour generation phase 1704. For example, the processing circuitry 114 may determine a length of time for the configuring the haircare appliance 100 in the wetting phase based on the liquid retention signal, so as to enable a desired amount of the liquid to be retained by the absorbent layer 134.

[0144] In other examples, though, the wetting phase may be omitted from the predefined styling procedure or may be performed prior to the predefined styling procedure. For example, the haircare appliance 100 need not comprise a reservoir 110. In such cases, liquid may be delivered to the absorbent layer 134 via a manual26 P005492-W001 or automated spray or by passing a wet brush over a surface of the barrel 102. The user may wet the absorbent layer 134 in between each curl (e.g. in between each execution of the predefined styling procedure).

[0145] After the wetting phase (if present), the vapour generation phase 1704 comprises a vaporisation phase, which may be referred to as a heating phase and can be considered to be a rapid or flash steaming phase in which vapour is rapidly applied to the hair by vaporising the liquid retained by the absorbent layer 134. In the vaporisation phase, the processing circuitry 114 configures the heater 132 in an on state, in which the heater 132 is heated to a sufficiently high temperature to vaporise the liquid retained by the absorbent layer 134. The processing circuitry 114 may control an electrical power supplied to the heater 132 so as to heat the heater 132 to a desired temperature for vaporisation. The desired temperature may be selected to reduce power consumption without unduly compromising styling performance. For example, the processing circuitry 114 may maintain the heater 132 so that a surface of the barrel 102 in contact with hair (such as the cover layer 136 for the haircare appliance 100 of Figure 1), is at a temperature of less than or equal to about 120 degrees Celsius.

[0146] The heater 132 may be heated to a temperature (referred to as a set barrel temperature) which is above a desired temperature for the surface of the barrel 102. However, the absorbent layer 134 typically acts as a buffer, and absorbs energy by evaporating the liquid into vapour so that the temperature of the surface of the barrel 102 (referred to in the context of Figure 2 as the surface temperature) is less than the set barrel temperature. For example, whereas the set barrel temperature may be above 100 degrees Celsius, the surface temperature may remain below 100 degrees Celsius during the vapour generation phase 1704. The relatively high temperature of the heater 132 rapidly heats liquid in contact with or adjacent to the heater 132 (e.g. due to proximity between the heater 132 and the absorbent layer 134 retaining the liquid) so as to rapidly vaporise the liquid. This may allow the vapour generation phase 1704 to be performed in less than around 10 seconds.

[0147] The vapour produced moves outwards, through the cover layer 136 and onto the hair. The vapour penetrates and condenses onto the hair, delivering condensation27 P005492-W001 energy and moisture, which both aid in styling by breaking hydrogen bonds in the hair and making the hair more malleable.

[0148] The airflow generator 112 is typically in an off state during the vapour generation phase 1704 to avoid blowing the vapour away from the hair before the vapour has had an opportunity to condense on the hair.

[0149] As the vapour generation phase 1704 comes to an end, e.g. as substantially all of the liquid is evaporated from the absorbent layer 134, the surface temperature of the barrel 102, e.g. corresponding to the temperature of an outer surface of the cover layer 136, begins to rise, and may rise gradually above 100 degrees Celsius. Once the surface temperature reaches the set barrel temperature, the power drawn by the heater 132 may drop noticeably. These phenomena can be detected by appropriate sensor(s) of the haircare appliance 100, and used by the processing circuitry 114 to trigger a subsequent, airflow generation phase 1706 of the predefined styling procedure. For example, the processing circuitry 114 may be configured to control the operation of the haircare appliance 100 to end the vapour generation phase 1704 based on a power signal indicative of a power consumed by the heater 132, as obtained by the power sensor 139. The processing circuitry 114 may be configured to control the operation of the haircare appliance 100 to end the vapour generation phase 1704 in response to the power signal indicating that a reduction in the power consumed by the heater 132 exceeds a threshold power reduction and / or the power consumed by the heater 132 is less than a threshold power. The processing circuitry 114 may also or instead be configured to end the vapour generation phase 1704 based on a temperature signal indicative of temperature of the barrel 102, e.g. as sensed by a temperature sensor such as the barrel temperature sensor 140. For example, the processing circuitry 114 may end the vapour generation phase 1704 in response to the barrel temperature sensor 140 exceeding a threshold temperature.

[0150] In other examples, though, the processing circuitry 114 may configure the haircare appliance 100 in the vapour generation phase 1704 for a predefined length of time, which may be more straightforward than adjusting a length of time of the vapour generation phase 1704 based on at least one sensor output.

[0151] After the vapour generation phase 1704, the processing circuitry 114 configures the haircare appliance 100 in the airflow generation phase 1706, in which28 P005492-W001 the haircare appliance 100 is 20 configured to generate an airflow, using the airflow generator 112, and to emit the airflow out of the haircare appliance 100 through the outlets of the barrel. The airflow may be used to dry the hair and / or set the style. The processing circuitry 114 is configured to turn the airflow generator 112 on in the airflow generation phase 1706.

[0152] In an example, the airflow generation phase 1706 comprises a heated airflow generation phase, in which the heater 132 is configured, by the processing circuitry 114, to heat the airflow generated by the airflow generator 112. This may aid drying of the hair, to remove excess moisture from the hair so as to improve the longevity of the style. In the heated airflow phase, the airflow generator 112 may provide an airflow through the barrel 102 and out of the outlets 30 in the barrel 102 with a flow rate (referred to as a first flow rate) of between around 1 and 5 litres per second. The heater 132 serves as an air heater during the heated airflow generation phase, due to heat exchange with the air. As a result, air exiting the outlets of the barrel are sufficiently warm to dry the hair. The airflow emitted out of the haircare appliance 100, through the outlets of the barrel 102, may be at a temperature (referred to as a first temperature) of between around 75 and 120 degrees Celsius, which is sufficient to dry the hair without damaging the hair.

[0153] To determine whether the hair is sufficiently dry to end the heated airflow generation phase, a capacitive sensor may be used to detect a liquid content of the hair in contact with the capacitive sensor. The heated airflow generation phase may be ended by the processing circuitry 114 in response to a signal obtained by the capacitive sensor (and provided to the control 10 system 114) indicating that the hair is sufficiently dry. In other examples, the predefined styling procedure may comprise a predefined length of time in the heated airflow generation phase or the processing circuitry 114 may be configured to determine a length of time for configuring the haircare appliance 100 in the heated airflow generation phase based on a length of time in the vapour generation phase 1704. For example, a duration of the heated airflow generation phase may be proportional to a duration of the vapour generation phase 1704, as a longer vapour generation phase 1704 typically delivers more water to the hair, so will take longer to dry.29 P005492-W001

[0154] In addition or instead, the heated airflow generation phase may be ended based on a temperature signal obtained by a temperature sensor (such as the barrel temperature sensor 140) indicative of the temperature of the barrel, e.g. if the temperature of the barrel exceeds a first predefined threshold temperature, such as 120 degrees Celsius. For example, a desired amount time for the heated airflow generation phase may be obtained by the processing circuitry 114 (e.g. as a predefined length of time, or a length of time that is proportional to a length of 25 time in the vapour generation phase 1704). The actual length of time the processing circuitry 114 configures the heated appliance 100 in the heated airflow generation phase may, however, be less than this, for example if the temperature of the barrel exceeds the first predefined threshold temperature before the desired amount of time has elapsed.

[0155] The heated airflow generation phase (which may be referred to as a “hot shot”) may be followed by a cooling airflow generation phase of the airflow generation phase 1706 (which may be referred to as a “cold shot”). A first temperature of the airflow emitted out of the haircare appliance 100 in the heated airflow generation phase is higher than a second temperature of the airflow emitted out of the haircare appliance 100 in the cooling airflow generation phase. For example, the cooling airflow generation phase may be used to lower a temperature of the hair to help set the style by reducing the malleability of the hair. Lowering the temperature of the haircare appliance 100 may also make the haircare appliance 100 safer to handle.

[0156] The first temperature may be at least 25 degrees higher than the second temperature. For example, for a first temperature of between 75 and 120 degrees Celsius, the second temperature may be less than 60 degrees Celsius.

[0157] To obtain the cooling airflow generation phase, the processing circuitry 114 may configure the heater 132 in an off state and the airflow generator 112 in an on state, so as to draw room temperature air into the haircare appliance 100, through the barrel 102 and out of the outlets in the barrel 102 so as to cool the barrel 102 and the hair wrapped around the barrel 102. The processing circuitry 114 may configure the airflow generator 112 to generate an airflow at a second flow rate in the cooling airflow generation phase, which may be higher than the first flow rate in the heated30 P005492-W001 airflow generation phase. For example, the second flow rate may be greater than 5 litres per second.

[0158] The predefined styling procedure may comprise a predefined length of time in the cooling airflow generation phase and / or the cooling airflow generation phase may be ended based on a temperature signal obtained by a temperature sensor (such as the barrel temperature sensor 140) indicative of the temperature of the barrel, e.g. if the temperature of the barrel is less than a second predefined threshold temperature, such as 60 degrees Celsius.

[0159] Following termination of the cooling airflow generation phase, the predefined styling procedure finishes 1708. The hair may be released, e.g. unwrapped, from the barrel 102. The processing circuitry 114 may configure the heater 132 to attain a predefined temperature (e.g. corresponding to a predefined dwell temperature) upon ending the airflow generation phase 1706. The predefined temperature may be selected to enable a rapid transition to vaporising the liquid, while still allowing comfortable handling of the haircare appliance 100 during wetting and / or wrapping of the hair for subsequent styling. The predefined temperature may for example be between around 40 and 60 degrees Celsius. The processing circuitry 114 may configure the heater 132 to attain the predefined temperature immediately prior to the vapour generation phase 1704, during the vapour generation phase 1704 and / or upon ending the airflow generation phase 1706 to improve the efficiency of performing the predefined styling procedure.

[0160] Figure 3 is a flow diagram 300 showing an operation of a haircare appliance, which may correspond to the haircare appliance 100 described with reference to Figures 1 and 2.

[0161] Figure 3 shows that the haircare appliance is operable in a dwell state 304 and in an active state 306.

[0162] In the example shown in Figure 3, when the haircare appliance is first turned on 302, the haircare appliance may be entered into the dwell state 304. The processing circuitry is configured to control the power supplied to the heater to increase the temperature of the heater to a dwell temperature and subsequently maintain the temperature of the heater at the dwell temperature in the dwell state 304. The dwell temperature is approximately 60°C.31 P005492-W001

[0163] Therefore, in the dwell state 304, the haircare appliance may be safer for the user to handle and wrap their hair around.

[0164] The haircare appliance can be switched into the active state 306, from the dwell state 304. For example, the processing circuitry may be configured to switch the haircare appliance from the dwell state 304 into the active state 306 in response to receiving a user input (e.g., via the start button). The processing circuitry is configured to control the power supplied to the heater to increase the temperature of the heater to an operating temperature in the active state 306.

[0165] The operating temperature is high enough for the haircare appliance to style the hair. For example, the operating temperature may be the target temperature of the heater during the predefined styling procedure. The operating temperature during the vaporisation phase may be at least 100°C, for example.

[0166] Because the haircare appliance is switched into the active state 306 from the dwell state 304 (in which the temperature of the heater is maintained at 60°C, the time which it takes for the heater to heat up to the operating temperature when the haircare appliance is switched into the active state 306 may be decreased).

[0167] The haircare appliance switches back into the dwell state 304 automatically after the predefined styling procedure has been completed. The processing circuitry is configured to: receive a completion signal indicating an end of a final phase (e.g., the airflow generation phase) in the styling procedure; and switch the haircare appliance from the active state 306 into the dwell state 304 in response to receiving the completion signal. For example, the completion signal may indicate that the time period in which the haircare appliance has been in the final phase has reached a threshold time period.

[0168] The haircare appliance continues to switch from the dwell state 304 to the active state 306 (in response to the user input) and from the active state 306 to the dwell state 304 (when the predefined styling procedure is completed) until the haircare appliance is switched off 308 (e.g., via a user input).

[0169] To control the temperature of the heater in the dwell state 304 and in the active state 306, the processing circuitry uses a temperature feedback loop such as a PI controller.32 P005492-W001

[0170] To increase the speed at which the temperature of the heater is increased to the operating temperature from the dwell temperature, a maximum power (i.e., the power rating of the heater) is supplied to the heater in the active state 306 when the heater is at the dwell temperature. In this example, the power rating of the heater is 400W.

[0171] In general, the power supplied to a heater will decrease with increasing temperature of the heater (for the same input voltage), due to the resistance of the heater increasing with increasing temperature. Therefore, the power supplied to the heater will increase with increasing temperature above the dwell temperature.

[0172] Because the maximum power is supplied at the dwell temperature, it is important to ensure that the power supplied to the heater does not exceed the maximum power (i.e., the power rating of the heater) when the temperature of the heater is below the dwell temperature.

[0173] Figures 4 and 5 are plots which show, for a constant voltage across a heater, the power supplied to the heater and the resistance of the heater as the temperature of the heater increases. In the example of Figure 4, 400W is supplied to the heater at 0°C. As shown in Figure 4, the power supplied to the heater drops to below 350W when the temperature of the heater is at 60°C.

[0174] Figure 5 shows that setting 400W at 60°C results in 1.29Q at 60°C which increases to 1. 93Q at 160°C and can provide 317W. This is 37W more than for a heater specified at 400W at 0°C, as shown in Figure 4. However, Figure 5 shows that to achieve 400W supplied to the heater at 60°C, a power rating of 475W is required for the heater, as the power supplied to the heater at 0°C is 475W. A heater of this power rating is significantly more expensive.

[0175] To overcome these problems, the haircare appliance of the present disclosure is operable in a pre-heating mode when the temperature of the heater is less than a threshold temperature (equal to the dwell temperature in this example), and in a primary heating mode when the temperature of the heater is greater than or equal to the threshold temperature. A lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.33 P005492-W001

[0176] Figure 6 is a flow diagram 600 showing an operation of a haircare appliance, which may correspond to the haircare appliance 100 described with reference to Figures 1, 2 and 3.

[0177] As shown in Figure 6, after the haircare appliance is switched on 602, the processing circuitry is configured to detect a temperature 604 of the heater. If the processing circuitry determines, at a decision step 606, that the detected temperature is less than the dwell temperature, the processing circuitry controls the power supplied to the heater in the pre-heating mode 608. If the processing circuitry determines, at the decision step 606, that the detected temperature is greater than or equal to the dwell temperature, the processing circuitry controls the power supplied to the heater in the primary heating mode 610.

[0178] The processing circuitry is configured to control the power supplied to the heater such that a power supplied to the heater remains below the power rating of the heater in the pre-heating mode 608. The processing circuitry is configured to control power supplied to the heater such that a power equal to a power rating of the heater is supplied to the heater in the primary heating mode 610 at the dwell temperature.

[0179] The processing circuitry is configured to control the power supplied to the heater by controlling individual heating elements of the heater. The heater comprises a first heating element and a second heating element connected in parallel with one another. In some examples, the lower power in the pre-heating mode 608 is achieved by turning on the first heating element and the second heating element in an alternating manner (or one at a time) in the pre-heating mode 608. The higher power in the primary mode is achieved by turning on the first heating element and the second heating element simultaneously in the primary heating mode 610.

[0180] Figure 7 is a plot showing, for the haircare appliance of the present disclosure, the power supplied to the heater and the resistance of the heater as the temperature of the heater increases. Figure 7 shows that, below the dwell temperature (60°C), a lower power is supplied to the heater, when the heating elements are turned on in an alternating manner. At the dwell temperature, the maximum power of 400W is supplied to the heater (200W is supplied to each of the heating elements, which are turned on simultaneously). Above the dwell temperature, the power supplied to the heater gradually decreases with increasing temperature. As shown in Figure 7, the34 P005492-W001 total power supplied to the heater at 160°C is 335W, which is greater than the total power supplied to the heater at 160°C shown in Figure 5. As further shown in Figure 7, the total power supplied to the heaters at 0°C is 217W. Therefore, the power ratings of the heating elements are only required to be 217W.

[0181] The processing circuitry is configured to control the power supplied to the heater in the pre-heating mode 608 such that power is supplied to the first heating element according to a first duty cycle, and power is supplied to the second heating element according to a second duty cycle. The first duty cycle and the second duty cycle are equal to achieve more even heating.

[0182] Figure 8 shows examples of the first and second duty cycles. On the righthand side, Figure 8 shows examples of the power / current draw from the first heating element (Hl) and from the second heating element (H2), and on the left hand side, Figure 8 shows respective corresponding power / current draw from the power source (e.g., the mains). The total duty cycle, corresponding to the sum of the first duty cycle and the second duty cycle are indicated adjacent the plots on the left-hand side. As shown in Figure 8, in each example, the power draw from the mains is balanced over the positive and negative cycles over a 6 cycle period, in accordance with standard requirements.

[0183] The examples described above are illustrative of the present disclosure, and further examples are envisaged. It is to be understood that any feature described in relation to any one example may be used alone or in combination with other features of the example, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the disclosure, which is defined in the accompanying claims.

Claims

35 P005492-W001CLAIMS1. A haircare appliance comprising: a heater and, processing circuitry configured to: detect a temperature of the heater; control a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, control a power supplied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature, wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.

2. The haircare appliance of claim 1, wherein the heater comprises a first heating element and a second heating element and wherein the processing circuitry is configured to control the power supplied to the heater such that power is supplied: to the first heating element and the second heating element in an alternating manner in the pre-heating mode; and, to the first heating element and the second heating element simultaneously in the primary heating mode.

3. The haircare appliance of claim 2, wherein the processing circuitry is configured to: apply an input voltage across the first heating element and the second heating element in an alternating manner in the pre-heating mode; and, apply the input voltage across the first heating element and the second heating element simultaneously in the primary heating mode.

4. The haircare appliance of claim 2 or claim 3, wherein the first heating element has substantially the same resistance as the second heating element.36 P005492-W0015. The haircare appliance of any of claims 2 to 4, wherein the processing circuitry is configured to control the power supplied to the heater such that, in the pre-heating mode power is supplied: to the first heating element according to a first duty cycle; and to the second heating element according to a second duty cycle; and, wherein the first duty cycle is the same as the second duty cycle.

6. The haircare appliance of any of the preceding claims, wherein the processing circuitry is configured to control the power supplied to the heater such that power is supplied to the heater according to a total duty cycle in the pre-heating mode, wherein the total duty cycle is equal to 100%.

7. The haircare appliance of any of claims 1 to 5, wherein the processing circuitry is configured to control the power supplied to the heater such that power is supplied to the heater according to a total duty cycle in the pre-heating mode, wherein the total duty cycle is less than 100%.

8. The haircare appliance of any of the preceding claims, wherein the processing circuitry is configured to control the power supplied to the heater such that a power of no more than 400 W is supplied to the heater in the primary heating mode.

9. The haircare appliance of any of the preceding claims, wherein the processing circuitry is configured to control the power supplied to the heater such that a power equal to a power rating of the heater is supplied to the heater in the primary heating mode.

10. The haircare appliance of any of the preceding claims, wherein the haircare appliance is operable in an active state and in a dwell state, and wherein the processing circuitry is further configured to: control the heater to reach an operating temperature when the haircare appliance is in the active state; and, control the heater to maintain a dwell temperature when the haircare appliance is in the dwell state,37 P005492-W001 wherein the operating temperature is greater than or equal to 70 degrees Celsius, and the dwell temperature is less than 70 degrees Celsius.

11. The haircare appliance of claim 10 wherein the threshold temperature is equal to the dwell temperature.

12. The haircare appliance of claim 10 or claim 11, wherein the processing circuitry is configured to use a temperature feedback control loop to control the heater to maintain the dwell temperature and to reach the operating temperature.

13. The haircare appliance of any of claims 10 to 12, wherein the processing circuitry is configured to: measure a time period; and, switch the haircare appliance from the active state into the dwell state in response to the measured time period reaching a threshold time period.

14. The haircare appliance of any of claims 10 to 13, wherein the processing circuitry is further configured to: receive a user input; and, switch the haircare appliance from the dwell state into the active state in response to receiving the user input.

15. A computer-implemented method for controlling a power applied to a heater of a haircare appliance, the computer-implemented method comprising: detecting a temperature of the heater; controlling a power supplied to the heater in a pre-heating mode in response to the detected temperature being less than a threshold temperature; and, controlling a power applied to the heater in a primary heating mode in response to the detected temperature being greater than or equal to the threshold temperature; wherein a lower power is supplied to the heater in the pre-heating mode than in the primary heating mode.38 P005492-W00116. A computer programme product comprising instructions which, when executed by a computer cause the computer to carry out the steps of the computer-implemented method of claim 15.

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