Haircare appliance

Abstract

A haircare appliance having a housing with an air inlet and an air outlet, an air flow generator for generating an air flow from the air inlet to the air outlet, and a heater for heating the air flow. The haircare appliance has an air flow temperature module for obtaining a value indicative of a temperature of the air flow at the air outlet, a distance sensor for sensing a distance to hair within a flow path from the air outlet, and a temperature sensor for sensing a temperature of the hair. The haircare appliance has a moisture estimation module configured to estimate a moisture content of the hair based on output values received from the air flow temperature module, the distance sensor, and the temperature sensor.

Description

TECHNICAL FIELD

[0001] The present invention relates to a haircare appliance. BACKGROUND

[0002] During blow-drying, the hair can reach a state of "over-drying". This can increase the susceptibility of the hair to mechanical or heat-related damage, and have a negative impact on its appearance, feel and the retention of any fixed style. In order to mitigate this, it can be desirable to determine the moisture content of the hair being dried, such that drying can be stopped before the "over-drying" state is reached. SUMMARY

[0003] According to a first aspect of the present invention, there is provided a haircare appliance comprising a housing having an air inlet and an air outlet, an airflow generator for generating an airflow from the air inlet to the air outlet, a heater for heating the airflow, an airflow temperature module for obtaining a value indicative of the temperature of the airflow at the air outlet, a distance sensor for sensing a distance to hair within a flow path from the air outlet, a temperature sensor for sensing a temperature of the hair, and a moisture estimation module configured to estimate a moisture content of the hair based on output values received from the airflow temperature module, the distance sensor and the temperature sensor.

[0004] The haircare appliance according to the first aspect of the present invention can be beneficial because the moisture estimation module utilises a value indicative of the temperature of the airflow at the air outlet, the distance between the air outlet and the hair within the flow path from the air outlet, and the temperature of the hair to estimate the moisture content of the hair.

[0005] In particular, when hair is exposed to forced hot convection, such as the hot convection generated by a hairdryer, the surface temperature of the hair can vary in proportion to its moisture content. As moisture is removed from the hair, its surface temperature increases, and this can occur at a decreasing rate as the hair tends towards a minimum moisture content level / equilibrium. The lower temperature of wet hair can be caused by the evaporative cooling effect and the larger inherent thermal mass.

[0006] The inventors of the present application have determined that, by observing the temperature difference between the hair and the airflow proximate to the hair, the moisture content of the hair can be reliably and accurately inferred, and have recognised that this temperature difference can be influenced by the distance of the air outlet, and therefore also by the distance of the haircare appliance from the hair.

[0007] The moisture estimation module can be configured to estimate the temperature of the airflow proximate to the hair based on outputs received from the airflow temperature module and the distance sensor, and to estimate the moisture content of the hair based on the output received from the temperature sensor and the estimated temperature of the airflow proximate to the hair.

[0008] The distance sensor can be located in the vicinity of the air outlet. The distance sensor can be configured to sense a distance between the air outlet and the hair.

[0009] The received output value can comprise a transient value. This can enable the moisture content to be estimated more quickly than, for example, an estimation method using a time average value.

[0010] The temperature sensor can comprise a non-contact temperature sensor, for example a sensor configured to measure a hair surface temperature without contacting the hair. The temperature sensor can comprise a thermopile. The distance sensor can comprise a time-of-flight sensor.

[0011] The airflow temperature module can be configured to directly determine a value indicative of an airflow temperature at the air outlet. For example, the airflow temperature module can comprise a further temperature sensor to directly obtain a value indicative of an airflow temperature at the air outlet. The further temperature sensor can comprise any one of a thermistor, a thermocouple or a resistance temperature detector (RTD). Directly obtaining a value indicative of an airflow temperature at the air outlet can provide a more accurate temperature determination than, for example, indirectly obtaining a value indicative of an airflow temperature at the air outlet.

[0012] The airflow temperature module can be configured to indirectly obtain a value indicative of an airflow temperature at the air outlet. For example, the airflow temperature module can be configured to infer a value indicative of an airflow temperature at the air outlet based on an operational standard of other components of the haircare appliance. Indirectly obtaining a value indicative of an airflow temperature at the air outlet can require fewer components than directly obtaining a value indicative of an airflow temperature at the air outlet, and so can reduce cost. The airflow temperature module can be configured to indirectly obtain a value indicative of an airflow temperature at the air outlet based on any one of a heater temperature of a heater, an airflow rate of an airflow generator or a power consumption of the haircare appliance. For example, the heater temperature can be utilised to infer a value indicative of an airflow temperature at the air outlet, and in some examples the heater temperature can be considered to be a value indicative of an airflow temperature at the air outlet.

[0013] The humidity estimation module can comprise a filter, and the filter can be configured to process an output of the distance sensor and an output of the temperature sensor to provide a normalised temperature reading. The distance between the air outlet and the hair can comprise a major noise source for the value measured by the temperature sensor, and changes in the distance can significantly alter the absolute value of the observed hair temperature, with the distance negatively correlating with the observed hair temperature. By measuring and modelling this noise source, the filter can be used to filter its influence, and the resulting humidity estimate can be normalised quickly without requiring a long time-based average. The filter can comprise an adaptive filter.

[0014] The humidity estimation module can comprise a mathematical model indicative of a relationship between a temperature of the airflow at the air outlet, a distance to the hair, and a temperature of the hair, and the humidity estimation module can be configured to estimate the moisture content of the hair based on the mathematical model. The mathematical model can enable a fast estimation of the moisture content without a direct reading from, for example, a moisture sensor. The humidity estimation module can comprise a lookup table, for example a 2D lookup table based on the airflow temperature near the hair and the hair temperature, or a 3D lookup table based on a value indicative of the airflow temperature at the air outlet, a distance to the hair within the flow path from the air outlet, and a sensed temperature of the hair.

[0015] The haircare appliance can comprise a motion sensor for determining a speed of motion of the haircare appliance relative to the hair, and the humidity estimation module can be configured to be inoperable when the speed of motion of the haircare appliance relative to the hair is above a threshold speed value. This can inhibit operation of the humidity estimation module in situations where any estimation result is at risk of being inaccurate, for example in situations where the haircare appliance is moving relatively fast relative to the hair. This can reduce power consumption, and is for example beneficial in situations where the haircare appliance is operated by a battery.

[0016] The motion sensor can comprise an inertial measurement unit. The threshold speed value can for example be about 50 mm / s.

[0017] The haircare appliance can comprise an image sensor for capturing images, and the humidity estimation module can be configured to be inoperable when an image captured by the image sensor does not indicate a presence of hair. This can inhibit false estimations of the moisture content in situations where the haircare appliance is positioned relative to objects other than hair. This can reduce power consumption, and is for example beneficial in situations where the haircare appliance is operated by a battery. The haircare appliance can comprise a processor for processing images captured by the image sensor, for example classifying objects contained in images captured by the image sensor. The processor can be configured to determine a presence or absence of hair in images captured by the image sensor, and can be configured to communicate a signal indicative of an absence of hair to a controller of the haircare appliance, for example a controller of the humidity estimation module. The imaging sensor can comprise a thermal imaging sensor. Wet hair can be cooler than dry hair, and a thermal imaging sensor can therefore be used to indicate a presence of hair to be dried.

[0018] The haircare appliance can comprise an environmental sensor for sensing an environmental temperature and / or humidity condition, and the humidity estimation module can estimate the moisture content of the hair based on an output received from the environmental sensor. The environmental temperature and / or humidity condition can influence the humidity level of the hair, and incorporating the sensed environmental temperature and / or humidity condition into the estimation of the moisture content of the hair can provide a more accurate estimation.

[0019] The haircare appliance can comprise an alert module to alert a user to an estimated moisture content of the hair. This can enable the user to, for example, stop drying of the hair and / or continue drying of a next portion of the hair in response to the estimated moisture content of the hair. This can inhibit over-drying of the hair, for example by providing an alert when the estimated moisture content is at or below a predetermined moisture content threshold. The alert module can be configured to alert the user when the estimated moisture content is at or below the predetermined moisture threshold. The predetermined moisture threshold can comprise a humidity value of 0%, for example to alert the user that the hair is at humidity equilibrium with the surrounding environment, or can comprise a value of 20%, for example to indicate that the humidity level of the hair is suitable for styling operations, for example curling.

[0020] The alert module can comprise a haptic feedback module, for example configured to provide haptic feedback to the user indicative of the estimated moisture content. This can ensure that the alert is provided to the user regardless of whether the haircare appliance is visible to the user.

[0021] The alert module can comprise a visual indicia of the estimated moisture content of the hair. For example, the alert module can comprise an LED or visual display screen to communicate the estimated moisture content of the hair to a user of the haircare appliance. The visual indicia can provide a simple way of communicating the alert to the user.

[0022] The alert module can comprise an audible indicia of the estimated moisture content of the hair. For example, the alert module can comprise a noise source to communicate the estimated moisture content of the hair to a user of the haircare appliance. The audible indicia can provide a simple way of communicating the alert to the user.

[0023] The haircare appliance can comprise a controller configured to control an output parameter of the haircare appliance based on the estimated moisture content. This can be beneficial as it can reduce the user input required to control the haircare appliance and can allow the haircare appliance to be controlled automatically in response to the estimated moisture content of the hair. The output parameter can comprise any of an airflow, an airflow temperature or an ion content.

[0024] The controller can be configured to modify an airflow rate of an airflow generator in response to the estimated moisture content, for example to increase or decrease the airflow rate of the airflow generator.

[0025] The controller can be configured to modify a temperature of a heater in response to the estimated moisture content, for example to increase or decrease the temperature of the heater. The controller can be configured to modify an electrical power supplied to the heater in response to the estimated moisture content, for example to increase or decrease the level of electrical power supplied to the heater.

[0026] The haircare appliance can comprise an ion generator for introducing ions into the airflow, and the controller can be configured to modify an ion generation rate of the ion generator in response to the estimated moisture content, for example to increase or decrease the ion generation rate of the ion generator.

[0027] The moisture estimation module can be configured to monitor the output values received from the temperature sensor over a period of time, calculate a heating rate of the hair, and estimate the moisture content of the hair based on the calculated heating rate. Dry hair can have a fast heating rate before tending towards a stable peak temperature, while wet hair can take a longer time to reach the same stable peak temperature. The heating rate can therefore be used to infer the estimated moisture content, and can increase the accuracy of the moisture estimation.

[0028] The moisture estimation module can be configured to receive output values indicative of the airflow rate, such as the airflow rate of the airflow generated by the airflow generator, and estimate the moisture content of the hair based on the output values indicative of the airflow rate. The airflow rate can have an effect on the drying rate of the hair, so taking the airflow rate into account can more accurately estimate the moisture content. The moisture estimation module can be configured to filter the output values indicative of the airflow rate and / or apply a correction factor determined based on the output values indicative of the airflow rate.

[0029] The haircare appliance can comprise a timer for timing the drying operation, and the moisture estimation module can be configured to estimate the moisture content of the hair based on output received from the timer. For example, a longer drying time can result in a decrease in the moisture level, and including a time-based element in the estimation of the moisture content can enable a more accurate estimation of the moisture content of the hair.

[0030] The moisture estimation module can be configured to receive input values indicative of a hair property of the hair, and estimate the moisture content of the hair based on the input values indicative of the hair property. Different hair properties can affect the moisture retention level of the hair, and estimating the moisture content of the hair based on the input values indicative of the hair property can enable a more accurate estimation of the moisture content.

[0031] The hair property can comprise any one of a hair type, a hair length, a hair colour, or a haircare product used on the hair.

[0032] The haircare appliance can comprise a user interface, and the input values indicative of the hair property can be received via the user interface. This can provide a simple means for a user to input the hair property before or during styling.

[0033] In other examples, the input values indicative of the hair property can be received from a remote device, such as a device remote from the haircare appliance. The remote device can comprise a computing device such as a phone or tablet, and the input values indicative of the hair property can be input to the remote device via an application. This can enable the input values indicative of the hair property to be input during styling without requiring the user to remove the haircare appliance from its current position relative to the hair.

[0034] The distance sensor can be configured to sense a distance to hair outside the flow path from the air outlet, the temperature sensor can be configured to sense a temperature of hair located outside the flow path from the air outlet, and the moisture estimation module can be configured to estimate a moisture content of hair located outside the flow path from the air outlet based on output values received from the distance sensor and the temperature sensor. This can enable analysis of hair that does not correspond to hair that is currently being heated, which can enable the use of pre-heating and / or post-heating information, for example to determine whether hair adjacent to hair that is currently being dried has been dried previously.

[0035] The haircare appliance can comprise a main body, an airflow generator and a heater housed within the main body, and an accessory releasably attachable to the main body, the accessory comprising an airflow temperature module, a distance sensor, a temperature sensor and a moisture estimation module. By providing the airflow temperature module, the distance sensor, the temperature sensor and the moisture estimation module as part of a releasable accessory, the moisture estimation functionality can be selectively utilised by a user and can also be retrofitted to an existing haircare appliance.

[0036] The accessory can be configured to communicate the estimated hair moisture content to the main body, for example via a wired or wireless connection. The accessory can comprise a transmitter configured to transmit the estimated moisture content information, and the main body can comprise a receiver configured to receive the estimated moisture content information from the transmitter. This can for example allow components located within the main body, for example the heater and the airflow generator, to be controlled based on the estimated moisture content of the hair.

[0037] The accessory can comprise an alarm module, and a power supply to power the alarm module, the airflow temperature module, the distance sensor, the temperature sensor and the moisture estimation module. In this way, the accessory can comprise a standalone unit for retrofitting to an existing haircare appliance.

[0038] According to a second aspect of the application, there is provided a method of estimating a moisture content of hair, the method comprising directing an airflow towards the hair, receiving a value indicative of a temperature of the airflow, receiving a value indicative of a distance to the hair, receiving a value indicative of a temperature of the hair, and estimating the moisture content based on the received values indicative of the temperature of the airflow, the distance to the hair and the temperature of the hair.

[0039] According to a third aspect of the application, there is provided an accessory for a haircare appliance, the accessory having an air flow generator configured to generate an air flow and a heater for heating the air flow, the air flow generator and the heater being arranged in a housing, the accessory comprising an air inlet for receiving the heated air flow from the housing, an air outlet, an air flow temperature module for determining a temperature of the air flow at the air outlet, a distance sensor for sensing a distance to hair within a flow path from the air outlet, a temperature sensor for sensing a temperature of the hair, and a humidity estimation module configured to estimate a moisture content of the hair based on output values received from the air flow temperature module, the distance sensor and the temperature sensor.

[0040] Optional features of one aspect of the application can be equally applied to other aspects of the application where suitable. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a schematic view of a haircare appliance according to the application;

[0042] Figure 2 is a graph showing a hair temperature profile from wet to dry;

[0043] Figure 3 is a graph showing a comparison between heating rates for wet and dry hair;

[0044] Figure 4 is a graph showing the effect of distance on dry hair surface temperature at different heater temperatures;

[0045] Figure 5 is a graph showing hair temperature versus humidity value at a given distance offset;

[0046] Figure 6 is a graph showing the relationship between hair temperature and humidity value for several distance offsets;

[0047] Figure 7 is a first schematic view of a 3D lookup table for use with the haircare appliance of Figure 1 ;

[0048] Figure 8 is a second schematic view of a 3D lookup table for use with the haircare appliance of Figure 1 ;

[0049] Figure 9 is a schematic view of the relationship between mass increase and humidity value;

[0050] Figure 10 is a schematic view of an adaptive filter system for use with the haircare appliance of Figure 1 ;

[0051] Figure 11is a schematic view of a first alternative embodiment of a haircare appliance according to the present application;

[0052] Figure 12 is a schematic view of a second alternative embodiment of a haircare appliance according to the present application;

[0053] Figure 13 is a schematic view of a third alternative embodiment of a haircare appliance according to the present application;

[0054] Figure 14 is a schematic view of a fourth alternative embodiment of a haircare appliance according to the present application;

[0055] Figure 15 is a schematic view of a fifth alternative embodiment of a haircare appliance according to the present application;

[0056] Figure 16 is a flowchart illustrating a method according to the present application. DETAILED DESCRIPTION

[0057] Figure 1 A haircare appliance according to the present application is shown schematically and generally designated 10. Figure 1 The haircare appliance 10 is intended to be connected to an AC mains power supply via a suitable cable (not shown), although it will be appreciated that embodiments are also envisaged in which the haircare appliance 10 comprises its own power supply (e.g. its own battery).

[0058] The haircare appliance 10 comprises a housing 12, an airflow generator 14, a heater 16, an airflow temperature module 18, a distance sensor 20, a temperature sensor 22 and a moisture estimation module 24.

[0059] The housing 12 comprises a handle portion 26 and a main body portion 28. The handle portion 26 is generally tubular and is hollow. The handle portion 26 comprises an air inlet 30 in the form of a plurality of holes, and the handle portion 26 also houses the airflow generator 14. A user interface 32 is provided on the handle portion 26 and comprises a plurality of user-actuatable buttons and / or a touch screen interface.

[0060] The main body portion 28 is generally cylindrical in form, but tapers towards an air outlet 34 of the haircare appliance 10, such that one end of the main body portion 28 is generally frustoconical. The main body portion 28 is hollow and houses the heater 16, the airflow temperature module 18, the distance sensor 20, the temperature sensor 22 and the moisture estimation module 24. The air outlet 34 can comprise a generally circular aperture, or in embodiments in which the main body portion 28 has a central bore, the air outlet 34 can be generally annular and arranged radially outwardly of the central bore.

[0061] The airflow generator 14 includes a motor-driven impeller to draw airflow into the housing 12 via the air inlet 30. An example of a suitable airflow generator 14 is the Dyson® Digital Motor V9 manufactured by Dyson Technology, Inc. In use, the airflow generator 14 produces airflow from the air inlet 30 through the handle portion 26 and the body portion 28 to the air outlet 34.

[0062] The heater 16 is disposed in the main body portion 28 of the housing 12 and configured to convectively heat the airflow flowing through the main body portion 28 during use, such that the heated airflow exits the housing 12 of the hair care appliance 10 via the air outlet 34. For example, a suitable heater may be a ceramic heater.

[0063] The airflow temperature module 18 is located in the main body 28 of the housing 12, near the air outlet 34. Figure 1 The airflow temperature module 18 in the embodiments includes a direct temperature sensor, such as a thermistor, thermocouple, or resistance temperature detector (RTD), configured to directly determine the airflow temperature at air outlet 34. It should be understood that alternative embodiments in which the airflow temperature module 18 is configured to indirectly determine the airflow temperature at air outlet 34 are also conceivable. For example, the airflow temperature module 18 may be configured to infer the airflow temperature at air outlet 34 based on any one of the heater temperature of heater 16, the airflow rate of airflow generator 14, or the power consumption of hair care appliance 10.

[0064] The distance sensor 20 is disposed in the main body 28 of the housing 12, near the air outlet 34. Figure 1 The distance sensor 20 in the embodiment includes a laser time-of-flight sensor, although it will be understood that other types of distance sensors may also be used. The distance sensor is configured to sense the distance of a hair within a flow path from air outlet 34 to the hair emerging from air outlet 34 during use.

[0065] Although Figure 1 In one embodiment, distance sensor 20 is located near the air outlet 34, but in other embodiments, distance sensor may be located further away from air outlet 34, applying an appropriate offset to any distance measurement to determine the distance of a hair from air outlet 34 to the flow path from air outlet 34.

[0066] Temperature sensor 22 is disposed in the main body 28 of housing 12, near air outlet 34. Figure 1The temperature sensor 22 in embodiments comprises a thermopile configured to sense the surface temperature of the hair within the flow path from the air outlet 34, although it will be appreciated that other types of non-contact temperature sensor can also be envisaged. It will further be appreciated that the temperature sensor 22 can be located further away from the air outlet 34 if required, to mitigate interference with the heated airflow.

[0067] The humidity estimation module 24 is configured to receive output values from each of the airflow temperature module 18, the distance sensor 20 and the temperature sensor 22, and to estimate the moisture content of the hair within the flow path from the air outlet 34 based on the received output values.

[0068] In particular, the surface temperature of the hair can vary in proportion to its moisture content when exposed to forced hot convection. As moisture is removed from the hair, its surface temperature increases, and this can occur at a decreasing rate as the hair tends towards a minimum moisture content level / equilibrium. The lower temperature of wet hair can be caused by evaporative cooling effects and the inherently greater thermal mass. This is illustrated in Figure 2 and Figure 3 as shown.

[0069] The inventors of the present application have determined that by observing the temperature differential between the hair and the airflow proximate to the hair, the moisture content of the hair can be reliably and accurately inferred, and have recognised that this temperature differential can be influenced by the distance of the air outlet, and therefore also the distance of the haircare appliance from the hair.

[0070] The humidity estimation module 24 is therefore configured to estimate the temperature of the airflow proximate to the hair based on the outputs received from the airflow temperature module 18 and the distance sensor 20, and to estimate the moisture content of the hair based on the output received from the temperature sensor 22 and the estimated temperature of the airflow proximate to the hair.

[0071] The relationship between the received outputs and the moisture content can be obtained through simulation and / or mathematical modelling and / or physical testing, and pre-programmed into the humidity estimation module 24.

[0072] In particular, as Figure 4 illustrated, for a given heating mode of the haircare appliance 10, i.e. the heater 16 is set to a particular temperature, the air temperature at the air outlet 34 can therefore be inferred, and the surface temperature of dry hair, i.e. hair determined to have a moisture content (i.e. humidity value) of 0%, varies with the distance of the haircare appliance 10 from the hair, as measured by the distance sensor 20. The surface temperature of wet hair, i.e. hair determined to have a moisture content (i.e. humidity value) of 100%, will also vary in a similar manner.

[0073] For a particular measurement offset used in a given heating mode, i.e. for a given temperature at the air outlet 34, the surface temperature of the hair can be measured and then a value indicative of the moisture content, i.e. a humidity value, can be obtained, which is labelled as humidity in the curves of Figure 5 An example of the effect of distance on humidity can be seen in Figure 6

[0074] In practice, a 3D look-up table can be utilised to obtain a humidity value from the received outputs from the airflow temperature module 18, the distance sensor 20 and the temperature sensor 22. Figure 7 and 8 illustrate an illustrative 3D look-up table.

[0075] In the graphs of Figure 5 and 6 and the 3D look-up tables of Figure 7 and 8 the "humidity" value is considered to be an estimated moisture content of the hair. This humidity value is obtained by observing an increase in the mass of the hair due to the moisture content, as illustrated in Figure 9

[0076] In Figure 9 the hair is considered to have a predetermined mass at 0% relative humidity. The percentage increase in mass is then used to infer a humidity value. For example, a 14% increase in mass corresponds to 60% relative humidity and is considered to be a humidity value of 0%. For the purposes of discussion herein, an increase in mass below 14% is considered to have a humidity value of 0%, i.e. dry. A 25% increase in mass is considered to be a humidity value of 10% and a 125% increase in mass is considered to be a humidity value of 100%. Thus, the moisture content of the hair estimated by the humidity value can be correlated to the percentage increase in mass due to moisture.

[0077] Whilst a particular humidity value scale has been defined above, it will be appreciated that different humidity value scales can be used in practice to estimate the moisture content of the hair.

[0078] In some embodiments, the humidity estimation module 24 comprises a filter configured to process the output of the distance sensor 20 and the output of the temperature sensor 22 to provide a normalised temperature reading of the hair within the flow path from the air outlet 34.

[0079] The distance between the air outlet 34 and the hair can comprise a major source of noise in the value measured by the temperature sensor 22 and changes in the distance can significantly alter the absolute value of the observed hair temperature, as Figure 4 ​​As shown, the offset distance is negatively correlated with the observed hair temperature. By measuring and modeling this noise source, its influence can be filtered using a filter, and the resulting moisture estimate can be quickly normalized without the need for long time-based averaging.

[0080] Figure 10 A suitable adaptive filter system 100 is shown schematically.

[0081] The adaptive filter system 100 receives a sensed hair temperature from the temperature sensor 22, which is shown in Figure 10 as the signal source, and a sensed distance from the distance sensor 20, which is shown in Figure 10 as x(n). The signal source and x(n) are added to obtain d(n), which represents the sensed hair temperature plus the noise introduced due to the distance from the hair. The sensed distance from the distance sensor 20 is fed to the adaptive filter 102, which uses an algorithm (in this case a least mean squares algorithm) to produce a filter output shown in Figure 10 as y(n). The filter output y(n) is removed from the value d(n) to produce an output value e(n) that is only an approximation of the signal source.

[0082] The use of the adaptive filter system 100 as Figure 10 shown can enable the haircare appliance 10 to dynamically converge on a relationship that indicates the moisture content from the received output, and can eliminate the need for a large amount of simulation and / or experimental work to determine the complete relationship, for example by producing a relationship that can only be fitted to one or two known points.

[0083] With knowledge of the estimated moisture content of the hair within the flow path from the air outlet 34, the haircare appliance 10 can be utilized to prevent over-drying of the hair in use.

[0084] As shown in Figure 11 , an alternative embodiment of the haircare appliance 200 comprises an alert module 202 disposed in the handle portion 26 of the housing 12. The alert module 202 can comprise any combination of haptic feedback modules, visual indicia, or audible indicia that can communicate the estimated moisture content of the hair to the user, for example when the estimated moisture content of the hair falls below a threshold value. This can enable the haircare appliance 200 to communicate the estimated moisture content to the user, which can inhibit over-drying of the hair in use.

[0085] Figure 12 Another alternative embodiment of the haircare appliance 300 is shown. Relative to the embodiment of the haircare appliance 10 of Figure 1 , Figure 12The haircare appliance 300 also comprises a controller 302 configured to control an output parameter of the haircare appliance based on the estimated moisture content estimated by the moisture estimation module 24. Examples of output parameters that can be controlled by the controller 302 are the flow rate of the airflow generated by the airflow generator 14, the temperature of the heater 16, and the ion content introduced into the airflow by an ioniser (not shown) of the haircare appliance 300. In this way, the haircare appliance 300 can reduce the user input required to control the haircare appliance 300 and can allow the haircare appliance 300 to be controlled automatically in response to the estimated hair moisture content.

[0086] Although shown here as a discrete controller 302, it will be appreciated that in practice the haircare appliance 300 can comprise a separate controller for each component contained therein or combinations thereof.

[0087] While shown in Figure 11 and 12 as separate embodiments, it will be appreciated that the alarm module 202 and the controller 302 can be combined into a single haircare appliance if desired.

[0088] Figure 13 A further alternative embodiment of a haircare appliance 400 is shown. Figure 13 The haircare appliance 400 of Figure 1 differs from the haircare appliance 10 of Figure 13 The haircare appliance 400 also comprises a motion sensor 402 for determining the speed of motion of the haircare appliance 400 relative to the hair within the flow path from the air outlet 34, and an image sensor 404 for capturing images.

[0089] The motion sensor 402 comprises an inertial measurement unit configured to determine the speed of motion of the haircare appliance 400 relative to the hair within the flow path from the air outlet 34, and the moisture estimation module 24 is configured to be inoperable in the event that the motion sensor 402 detects a speed of motion above a predetermined threshold, for example of about 50mm / s. This can inhibit operation of the moisture estimation module 24 in the event that there is a risk of inaccurate estimation results, for example in the event that the haircare appliance 400 is moving relatively quickly relative to the hair. This can reduce power consumption and is beneficial, for example, in the event that the haircare appliance 400 is operated by a battery.

[0090] Similarly, the moisture estimation module 24 is configured to be inoperable in response to the output of the image sensor 404, for example in the event that the images captured by the image sensor 404 do not indicate the presence of hair. Figure 13The image sensor 404 in embodiments of the haircare appliance 500 is a visible light image sensor in the form of a video camera and further comprises an image classifier to determine the presence or absence of hair in images, e.g. video frames, captured by the image sensor 404. Alternative image sensors are also envisaged, e.g. thermal imaging sensors or indeed any sensor capable of indicating the presence or absence of hair.

[0091] Although shown in Figure 13 as having both a motion sensor 402 and an image sensor 404, embodiments of the haircare appliance are also envisaged which utilise only one of these sensors.

[0092] Figure 14 Another embodiment of a haircare appliance 500 according to the present application is schematically illustrated. Figure 14 The haircare appliance 500 of Figure 1 differs from the haircare appliance 10 of Figure 14 The haircare appliance 500 further comprises an environmental sensor 502 configured to sense environmental conditions of the haircare appliance 500, e.g. any of the ambient temperature and the ambient humidity. The environmental sensor 502 provides an output value to the humidity estimation module 24, wherein the humidity estimation module 24 is configured to estimate the humidity of the hair within the flow path from the air outlet 34 based on the output received from the environmental sensor 502, e.g. by applying a bias to the estimated moisture content or the temperature of the hair sensed by the temperature sensor 20 depending on the magnitude of the reading from the environmental sensor 502.

[0093] It will be appreciated that the humidity estimation module 24 can also take into account other parameters during the estimation of the moisture content of the hair within the flow path from the air outlet 34.

[0094] For example, in one embodiment, the humidity estimation module 24 can be configured to monitor the output values received from the temperature sensor 22 over a period of time to calculate a heating rate of the hair within the flow path from the air outlet 34 and estimate the moisture content of the hair based on the calculated heating rate. In such an embodiment, the haircare appliance 10 can comprise a timer to calculate the heating rate.

[0095] In another embodiment, the humidity estimation module 24 can be configured to receive an output value indicative of the airflow rate, e.g. from the airflow generator 14 or a controller of the airflow generator 14, and estimate the moisture content of the hair within the flow path from the air outlet 34 based on the value indicative of the airflow rate. The airflow rate can for example influence the drying rate of the hair, so taking the airflow rate into account can more accurately estimate the moisture content.

[0096] In some embodiments, the moisture estimation module 24 can be configured to monitor the time of the drying operation and estimate the moisture content based on the time of the drying operation, for example by inferring the reduction in humidity level over time. In such embodiments, the haircare appliance 10 comprises a timer for timing the drying operation.

[0097] In another embodiment, the moisture estimation module 24 is configured to receive an input value indicative of a hair property of the hair within the flow path from the air outlet 34 and estimate the moisture content of the hair based on the input value indicative of the hair property. For example, the hair property can be any one of a hair type, a hair length, a hair colour or a haircare product used on the hair. In some embodiments, the hair property can be input via the user interface 32.

[0098] Figure 15 Another embodiment of a haircare appliance 600 is schematically illustrated. The haircare appliance 600 comprises an attachment 602 releasably attached to the housing 12. The attachment 602 can be releasably attached in any suitable manner, including for example magnetic attachment. The airflow temperature module 18, the distance sensor 20, the temperature sensor 22 and the moisture estimation module 24 are shown as being provided in the attachment 602 of the haircare appliance 600, but it will be appreciated that any suitable combination of the aforementioned components can be housed in the attachment 602 in practice. The attachment 602 receives the airflow from the air outlet 34 and provides the airflow to the target hair via its own air outlet 604. Figure 15

[0099] By positioning any combination of the airflow temperature module 18, the distance sensor 20, the temperature sensor 22 and the moisture estimation module 24 in the attachment 602, the functionality discussed above of estimating the moisture content of the hair within the flow path from the air outlet 604 can be selectively provided, and indeed can be retrofitted to an existing haircare appliance.

[0100] In embodiments in which the haircare appliance 600 comprises the distance sensor 20, the temperature sensor 22 and the moisture estimation module 24, the attachment 602 can be configured to receive an input value indicative of a hair property of the hair within the flow path from the air outlet 604 and estimate the moisture content of the hair based on the input value indicative of the hair property. Figure 15

[0101] In other embodiments, the attachment 602 is configured to communicate the estimated moisture content to the main body, for example to one or more controllers provided within the main body, so that an action can be taken in response to the estimated moisture content previously discussed. Suitably, the communication can be via wired or wireless communication methods. In such embodiments, the attachment 602 or components housed therein can be powered via the main body.

[0102] ​​In the above embodiments, each haircare appliance has a distance sensor 20 to sense a distance to hair within the flow path from the air outlet 34. In some embodiments, the distance sensor 20 is configured to sense a distance to hair outside the flow path from the air outlet 34, the temperature sensor 22 is configured to sense a temperature of hair located outside the flow path from the air outlet 34, and the moisture estimation module 24 is configured to estimate a moisture content of hair located outside the flow path from the air outlet 34 based on the output values received from the distance sensor 20 and the temperature sensor 22. This can enable analysis of hair that does not correspond to hair that is currently being heated, which can enable the use of pre-heat and / or post-heat information, for example to determine whether hair adjacent to hair that is currently being dried has been dried previously.

[0103] In Figure 16 The method 700 according to the application is schematically illustrated in the flowchart of figure 7. The method 700 comprises directing 702 an air flow towards hair, receiving 704 a value indicative of an air flow temperature, receiving 706 a value indicative of a distance to the hair, and receiving 708 a value indicative of a hair temperature. The method 700 comprises estimating 710 a moisture content of the hair based on the received values indicative of the air flow temperature, the distance to the hair, and the hair temperature.

Claims

1. A hair care appliance comprising a housing having an air inlet and an air outlet, an airflow generator for generating an airflow from the air inlet to the air outlet, a heater for heating the airflow, an airflow temperature module for obtaining a value indicating the temperature of the airflow at the air outlet, a distance sensor for sensing the distance of hair within a flow path from the air outlet, a temperature sensor for sensing the temperature of the hair, and a humidity estimation module configured to estimate the moisture content of the hair based on output values ​​received from said airflow temperature module, distance sensor, and temperature sensor. in, The hair care appliance includes at least one of the following: A motion sensor is used to determine the speed of movement of the hair care device relative to the hair, and the humidity estimation module is configured to be inoperable when the speed of movement of the hair care device relative to the hair is higher than a threshold speed value; and An image sensor is used to capture images, and the humidity estimation module is configured to be inoperable when the images captured by the image sensor do not indicate the presence of hair.

2. The hair care tool according to claim 1, wherein, The humidity estimation module is configured to estimate the temperature of the airflow near the hair based on the outputs received from the airflow temperature module and the distance sensor, and is configured to estimate the moisture content of the hair based on the outputs received from the temperature sensor and the estimated temperature of the airflow near the hair.

3. The hair care appliance according to claim 1 or 2, wherein, The humidity estimation module includes a filter, and the filter is configured to process the output of the distance sensor and the output of the temperature sensor to provide a standardized temperature reading.

4. The hair care appliance according to claim 1 or 2, wherein, The humidity estimation module includes a mathematical model indicating the relationship between the airflow temperature at the air outlet, the distance of the hair, and the temperature of the hair, and the humidity estimation module is configured to estimate the moisture content of the hair based on the mathematical model.

5. The hair care appliance according to claim 1 or 2, wherein, The hair care device includes an environmental sensor for sensing ambient temperature and / or humidity conditions, and the humidity estimation module estimates the moisture content of the hair based on the output received from the environmental sensor.

6. The hair care appliance according to claim 1 or 2, wherein, The hair care device includes an alarm module to alert the user to the estimated moisture content of the hair.

7. The hair care appliance according to claim 6, wherein, The alarm module includes at least one of a tactile feedback module for estimating the moisture content of hair, a visual marker, and an auditory marker.

8. The hair care appliance according to claim 1 or 2, wherein, The hair care device includes a controller configured to control the output parameters of the hair care device based on the estimated moisture content.

9. The hair care appliance according to claim 8, wherein, The output parameters include any one of the airflow, airflow temperature, or ion content.

10. The hair care appliance according to claim 1 or 2, wherein, The humidity estimation module is configured to monitor the output value received from the temperature sensor over a period of time, calculate the heating rate of the hair, and estimate the moisture content of the hair based on the calculated heating rate.

11. The hair care appliance according to claim 1 or 2, wherein, The humidity estimation module is configured to receive an output value indicating the airflow rate and to estimate the moisture content of the hair based on the output value indicating the airflow rate.

12. The hair care appliance according to claim 1 or 2, wherein, The hair care device includes a timer for timed drying operations, and the humidity estimation module is configured to estimate the moisture content of the hair based on the output received from the timer.

13. The hair care appliance according to claim 1 or 2, wherein, The humidity estimation module is configured to receive input values ​​indicating hair attributes and to estimate the moisture content of the hair based on the input values ​​indicating hair attributes.

14. The hair care appliance according to claim 13, wherein, The hair attribute is any of the following: hair type, hair length, hair color, or hair care products used on the hair.

15. The hair care appliance according to claim 13, wherein, The hair care device includes a user interface, and input values ​​indicating hair attributes are received via the user interface.

16. The hair care appliance according to claim 1 or 2, wherein, The distance sensor is configured to sense the distance of hair outside the flow path from the air outlet, the temperature sensor is configured to sense the temperature of hair located outside the flow path from the air outlet, and the humidity estimation module is configured to estimate the moisture content of hair located outside the flow path from the air outlet based on the output values ​​received from the distance sensor and the temperature sensor.

17. The hair care appliance according to claim 1 or 2, wherein, The hair care device includes a main body, an airflow generator and a heater housed within the main body, and accessories releasably attached to the main body, the accessories including an airflow temperature module, a distance sensor, a temperature sensor and a humidity estimation module.

18. The hair care appliance according to claim 17, wherein, The accessory is configured to transmit the estimated hair moisture content to the subject.

19. The hair care appliance according to claim 17, wherein, The accessory includes an alarm module and a power supply. The alarm module is used to alert the user to the estimated hair moisture content, and the power supply is used to power the alarm module, the airflow temperature module, the distance sensor, the temperature sensor, and the humidity estimation module.

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