Hair styling device and attachment

Abstract

An attachment (10, fig.3) for a hair styling device comprises an elongate body 1 which has a fluid inlet, a fluid outlet and a fluid flow path extending between the fluid inlet and the fluid outlet. A

Description

Field of the Invention The present invention relates to an attachment for a hair styling device. The present invention also relates to a hair styling device, such as a hair care device and / or heated hairstyling device. Background In conventional hair styling devices, air may be directed towards the hair of a user. The air may or may not be heated. When the air is heated, it is important that the hair is exposed to the hot air from the device for long enough that the hair maintains the style for a prolonged period after styling. However, it is also important that the hair is not exposed to heated air for longer than is necessary in order to avoid unnecessary damage to the hair resulting from the exposure to the heated air, and to reduce the amount of time required to style the hair. Conventionally, users of heated hairstyling devices are unaware how long hair should be exposed to hot air to achieve a long-lasting hairstyle. Users often touch the hair tresses being styled during the styling process to judge whether the hair has been successfully styled. However, it can be difficult for users to be consistent with their style readiness assessment. This can affect the results of the hair styling device an ultimately user satisfaction. Some hairstyling devices apply cold air to the hair tresses at the end of styling with hot air. This can lock in the style such that the hairstyle lasts longer, thus improving the results of the hairstyling device. However, users of these hair styling devices may not be aware of how long to apply the cold air to achieve the desired result. Furthermore, some users find holding down a button on the device for supplying cold air uncomfortable. Some hair styling devices operate by using air flow to wrap hair around an elongate barrel, e.g. to curl the hair. Ideally, the hair should be evenly wrapped around and along the barrel, in order to provide even heating of the hair, but this can be difficult to achieve. The present invention has been devised in light of the above considerations. Summary of the Invention According to a first aspect of the invention, there is provided an attachment for a hair styling device, the attachment comprising an elongate body extending from an attachment end to a tip, the attachment end for attaching to a handle of the hairstyling device, the elongate body comprising: a fluid inlet, a fluid outlet and a fluid flow path extending between the fluid inlet and the fluid outlet; at least two elongate plates extending in a direction along a longitudinal axis of the elongate body, wherein the at least two elongate plates are mounted on a sub assembly of the elongate body such that each of the plates forms an elongate slot between itself and the sub assembly, each slot defining a component of the fluid outlet; and a plurality of vanes for directing fluid in the fluid flow path towards the fluid outlet, wherein the plurality of vanes are positioned along each slot, and wherein a majority of the plurality of vanes are angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end. Each vane has a first surface for guiding fluid on its first side, and a second surface for guiding fluid on its second side, and each vane may therefore be characterised by its “vane axis”, the vane axis extending along a direction parallel to that in which its first and its second surface extend. The vane axis may form a vane angle of between 0° and 90° relative to the longitudinal axis of the elongate body. If a vane angle is less than 90° and the vane axis is pointing towards the attachment end (the downstream end), then the vane is understood to be angled to direct fluid towards the attachment end. Of course, an acute vane angle with respect to the attachment end, will mean that the vane has an oblique vane angle with respect to the tip end (the upstream end), since the vane is diverting fluid towards the attachment end and away from the tip end. By angling a majority of the plurality of vanes towards the attachment end relative to the longitudinal axis of the elongate body, when hair (e.g. one or more hair tresses) is wrapped around the elongate body, it wraps more evenly down the elongate body rather than over itself. This leads to an improved wrapping of the hair around the elongate body and therefore improved styling. Any moisture from the hair is also directed towards the attachment end. Optional features of the first aspect are set out below. As used herein, a majority of the plurality of vanes may be more than 50% of the plurality of vanes. A majority of the plurality of vanes may be more than 55%, more preferably more than 60%, more preferably more than 65%, more preferably more than 70%, more preferably more than 75%, more preferably more than 80%, more preferably more than 85%, more preferably more than 90%, more preferably more than 95%, of the plurality of vanes. Optionally, all of the plurality of vanes may be angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end. The plurality of vanes may be spaced along the length of the elongate body. The plurality of vanes may be spaced along the entire length of the elongate slot. In this way, the benefit of the directional fluid exiting each slot is achieved along the length of the elongate body. Alternatively, the plurality of vanes may be spaced only along a portion of the entire length of the elongate body. The plurality of vanes may be equally spaced along the length of the elongate slot. Alternatively, the spacing of the plurality of vanes may be unequal, and optionally irregular. The plurality of vanes may be progressively more closely spaced towards the tip of the elongate body. The plurality of vanes may be progressively more closely spaced towards the attachment end of the elongate body. At least some of the plurality of vanes may be angled relative to the longitudinal axis of the elongate body by different amounts to one another. In particular, the angle of at least some of the plurality of vanes may differ from the angle of other vanes (e.g. adjacent vanes). That is to say, the vane angles of the respective vanes vary along the length of the elongate body. The angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the attachment end is greater than the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the tip. In other words, the vane angle of one or more vanes at the attachment end may be greater than the vane angle of one or more vanes at the tip end. In this way, the vanes further from the attachment end may be angled more towards the attachment end than the vanes closer to the attachment end, which advantageously leads to a more even distribution of hair along the elongate body during wrapping. Optionally, the angle of the plurality of vanes with respect to the longitudinal axis of the elongate body may increase in a direction from the tip to the attachment end. The angles of the plurality of vanes may increase sequentially in the direction from the tip to the attachment end. The vane angle of one or more subsequent vane(s) with respect to the attachment end may increase with distance along the direction from the tip to the attachment end. The smaller (i.e. more acute) the vane angle, the more the vane ‘leans’ towards the attachment end and the larger component of fluid is that is directed towards the attachment end. The increase of vane angle may occur at each subsequent vane as you travel from the tip to the attachment end. Alternatively, pairs or other groupings of vanes may have the same vane angle as one another and the vane angle of each pair or other grouping may increase with proximity to the attachment end. The vane angle of a subsequent vane may increase at a constant rate in the direction from the tip to the attachment end. The vane angle of a subsequent vane may increase at a non-constant rate. In some examples, the rate of change of the vane angle between a subsequent vane may increase in the direction from the tip to the attachment end. In other examples, the rate of change of the vane angle between each subsequent vane may decrease in the direction from the tip to the attachment end. A maximum vane angle may be greater than 85°. A maximum vane angle may be less than 135°, less than 130°, less than 125°, less than 120°, less than 115°, less than 110°, less than 105°, less than 100°, or less than 95°. A maximum vane angle may be (approximately) 90°. For example, the maximum vane angle may be between 85° and 95°. The minimum vane angle may be less then 45°, less than 40°, less than 35°, less than 30°, less than 25°, less than 20°, less than 15°, less than 10°, less than 5°, less than 3°, for example. Optionally, the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the attachment end is between 60° and 90°. This angle relates to the acute angle formed between the direction of the longitudinal axis of the elongate member, and the vane axis of the vane. Of course, if a vane is angled (i.e. it is not transverse to the longitudinal axis of the elongate body) it will form an acute angle on one side, and an oblique angle on the other side. The acute angle is located on the side of the vane proximate to the direction in which fluid flow is desired. Optionally, the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the tip is less than 30°. Optionally, the slots may extend along a direction parallel to the longitudinal axis of the elongate body. Optionally the slots may extend along but also twist around the longitudinal axis of the elongate body Also disclosed is an attachment comprising a hybrid sensor, the hybrid sensor comprising a first sensing element configured to sense a temperature of a fluid flow stream directed by the plurality of vanes; and a second sensing element configured to sense a humidity of the fluid flow stream. Optionally, a plurality of hybrid sensors are provided spaced around the body of the attachment. Optionally, a hairstyling device may be provided comprising an attachment as set out above and also a handle, wherein the handle is configured to be reversibly attachable or permanently attached to the attachment end of the attachment. Optionally, the hairstyling device may further comprise one or more sensors. Optionally, the hair styling device may comprise a hybrid sensor, the hybrid sensor comprising: a first sensing element configured to sense a temperature of a fluid flow stream directed by the plurality of vanes; and a second sensing element configured to sense a humidity of the fluid flow stream. In this way, as the moisture of the hair is pushed towards the handle due to the angle of the vanes, the moisture can then be detected by the hybrid sensor. By measuring both the temperature and the humidity, the device is able to more accurately estimate the amount of moisture left in the hair during use. Optionally, the hybrid sensor can additionally include a pressure sensor. Optionally, the hybrid sensor is positioned on the handle. In this way an improved implementation is provided wherein no electrical connections are required to the elongate body, and the advantages of the sensor can be achieved in combination with the ability to provide passive hair styling attachment(s). At least part of the hybrid sensor may be positioned on the attachment. In some examples, part of the hybrid sensor may be positioned on the handle and part of the hybrid sensor may be positioned on the attachment. In some examples, the attachment comprises the hybrid sensor. The hybrid sensor may be positioned closer to the attaching end of the attachment (than the tip). This may be advantageous as the hybrid sensor is closer to the hair. The hybrid sensor may comprise a single sensor device or sensor chip comprising both the temperature sensing element and the humidity sensing element, e.g., with a common interface. Alternatively, the hybrid sensor may comprise a plurality of distinct sensing devices or chips, e.g., a temperature sensing device and a separate, distinct humidity sensing device. Optionally, the hybrid sensor (e.g., an assembly comprising the first sensing element and the second sensing element) is positioned closer to an end of the handle configured to be attached to the attachment than the other opposing end of the handle. By locating the hybrid sensor in such a location it is possible to enhance the signal to noise ratio. On the other hand, whilst it is advantageous to place the sensor at the attachment end of the handle, proximity to the attachment can introduce problems with thermal conduction from the attachment. In one or more embodiments, the hybrid sensor is located no less than 0.5cm, or 1cm or 2cm from the attachment end of the handle and / or no more than 2cm, 3cm, 5cm or 10cm from the attachment end of the handle. Optionally, the hairstyling device further comprises a controller, the controller being configured to calculate a moisture content value of hair being styled by the hair styling device based on a measured temperature and humidity of the fluid flow stream detected by the first and second sensor elements, respectively. The fluid flow stream may comprise water vapour entrained in an air flow, for example. The measured temperature and humidity of the fluid flow stream may be detected by the first and second sensor elements (substantially) simultaneously. The calculated moisture content value may be an estimated coefficient or score, for example. Optionally, the controller may be configured to detect whether hair is present on, adjacent to or around the device based on the calculated moisture content value. Optionally, the controller is configured to perform a control function based on the calculated moisture content value. Optionally, the control function is: outputting feedback indicating that the calculated moisture content value has met a predefined criterion; adjusting the power supplied to a heater and / or motor (for producing a fluid flow stream along the fluid flow path) of the hair styling device; and / or adjusting a duration of time in which power is supplied to the heater and / or motor (e.g. a styling duration). In this way, the hair styling device is automated for improved hair staying with reduced user interaction. Rather than relying upon intuition or subjective thresholds determined by the user, the operation of the hairstyling device is instead controlled in relation to actual measurements of moisture content. According to a second aspect of the invention, there is provided a hairstyling device comprising a hybrid sensor, the hybrid sensor comprising: a first sensing element configured to sense a temperature of a fluid flow stream; and a second sensing element configured to sense a humidity of the fluid flow stream. Optionally, the hybrid sensor can additionally include a pressure sensor. The hybrid sensor may be located on a main body (e.g. handle) of the hairstyling device, and, contrary to hair styling devices in the prior art, gas mixture including water vapour from hair may be received by the hybrid sensor in an open space. The hybrid sensor may be located on an attachment of the hairstyling device attached or attachable to a handle. Typically, the first sensing element and second sensing element may be located in the same region or location and so may be measuring the temperature and hydration of the same fluid stream. The temperature of the fluid flow stream detected by the first sensing element is correlated to the amount of air in the flow stream and therefore the amount of hair being styled. The humidity of the fluid flow stream detected by the second sensing element is indicative of the amount of moisture in the flow stream from the hair. A given humidity value for a small tress of hair may indicate that the hair is still wet and more styling is required. However, the same given humidity reading for a large tress of hair may indicate that styling is complete. By incorporating the two sensing elements together it is therefore possible to more accurately determine the amount of moisture in the hair. By better predicting the moisture content of the hair itself, styling can be improved and any efforts to control and / or automate the styling process can be made more accurate. In one or more embodiments, the hybrid sensor takes the form of an off the shelf component such as, but not limited to, Renesas HS4001, Sensirion SHT41, ST HTS221, ScioSense EN210, Texas Instrumants HDC3020 or similar. Optionally, the second sensing element is configured to sense a relative humidity of the fluid flow stream. A calibration sensor may allow for a correction of the temperature detected by the first sensing element, which may be affected by e.g. conductive heat from other elements, based on an independently measured temperature isolated from conductive heat sources. An environmental sensor may also be used to measure a reference point and the relative humidity measured against a measurement made by the environmental sensor. The environmental sensor may be located at a fluid inlet (described in further detail below). Optionally, the environmental sensor may be used to measure the reference point prior to an activation (e.g., initiation) of the fluid flow stream. Measuring a relative humidity of the fluid flow stream may alleviate the need to measure an absolute humidity value which may be difficult in situations where the temperature has faster temperature gradients. In one or more embodiments, the hair styling device further comprises a body for styling hair, the body having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet, wherein the fluid outlet is configured to direct the fluid flow stream towards the hybrid sensor. In one or more embodiments, the body may comprise an elongate body, the elongate body comprising: at least two elongate plates extending in a direction parallel to a longitudinal axis of the elongate body, wherein the at least two elongate plates overlap to form a slot therebetween, the slot defining the fluid outlet; and a plurality of vanes for directing fluid in the fluid flow path towards the fluid outlet, wherein the plurality of vanes are positioned in the slot between the at least two elongate plates, and wherein a majority of the plurality of vanes are angled relative to the longitudinal axis of the elongate body to direct fluid towards the hybrid sensor. In this way, as described in more detail above, the angle of the vanes directs the moisture of the hair towards the handle of the hairstyling device and onto the hybrid sensor. This improves signal to noise ratio and the accuracy of moisture measurement(s) of the hair. Optionally, as described in more detail above in relation to the first aspect, the angle of the plurality of vanes with respect to the longitudinal axis of the elongate body increases in a direction from the tip to the attachment end. Optionally, as described in more detail above in relation to the first aspect, the hairstyling device further comprises a controller, the controller being configured to calculate a moisture content value of hair being styled by the hairstyling device based on a measured temperature and humidity of the fluid flow stream detected by the first and second sensor elements, respectively. Optionally, the controller is configured to perform a control function based on the calculated moisture content value. Optionally, the control function is: outputting feedback indicating that the calculated moisture content value has met a predefined criterion; adjusting the power supplied to a heater and / or motor (for producing a fluid flow stream along the fluid flow path) of the hair styling device; and / or adjusting a duration of time in which power is supplied to the heater and / or motor (e.g., a style duration). The feedback may be output e.g. visually via a display on the device and / or haptically via a haptics module located on the device itself. Alternatively or additionally, the feedback may be output to a connected mobile device for display thereon. By providing feedback in the form of an alert or a control loop, the device provides an improved user experience, as the user does not have to judge when hair is dry enough. Optionally, the control function is reducing the power supplied to the heater and / or motor of the hair styling device when the calculated moisture content value has met a predefined criterion. In this way the need for user input is reduced which leads to a better user experience and more accurate results. Optionally, the hairstyling device further comprises a handle configured to be reversibly attachable or permanently attached to the attachment, wherein the hybrid sensor is positioned on the handle. Advantageously, in such an implementation, no electrical connections between the handle and attachment are required. The device can be used in conjunction with passive (and therefore cost effective) hair styling attachments. Optionally, as described in more detail above, the hybrid sensor is positioned closer to an end of the handle configured to be attached to the attachment than the other opposing end of the handle. Optionally, the hair styling device comprises a plurality of hybrid sensors. By providing multiple hybrid sensors, further data about the direction of the flow stream and the distribution of hair wrapped around the body is provided. In addition, the signal to noise ratio is also improved. Optionally, the plurality of hybrid sensors are spaced around a circumference of the handle. In this way, differences in measurements of the flow stream due, for example, to an uneven distribution of hair around the elongate body, may be taken into account. Optionally, the plurality of hybrid sensors are spaced around a circumference of the body of the attachment. Optionally, the hybrid sensors may be equally spaced around the circumference of the handle or body. The hair styling device may further comprise a fluid flow sensor. The fluid flow sensor can be used to indicate the mass of hair wrapped around the body. The variability of this mass may have consequences on the total airflow and will therefore influence dynamics of the hybrid sensor. The controller may therefore be configured to incorporate fluid flow measurements into any feedback, control or automation steps in addition to any data taken from the hybrid sensor. Optionally, as described in more detail above, the hairstyling device further comprises a calibration sensor configured to detect an environmental temperature and / or the temperature of the fluid flow stream. The calibration sensor allows for a correction of the temperature detected by the first sensing element, which may be affected by e.g. conductive heat from other elements, based on an independently measured temperature isolated from conductive heat sources. Optionally, the hair styling device further comprises a pressure sensor configured to detect an environmental pressure. The pressure sensor allows for a correction of the hybrid sensor readings particularly at high altitudes. The pressure sensor may be integrated into a single unit that forms the hybrid sensor, alternatively, the pressure sensor may be a distinct sensing device. The pressure sensor can measure a pressure of a fluid flow stream through the appliance. Alternatively, or additionally the pressure sensor can measure an environmental pressure, for example but measuring a pressure before the fluid flows through the appliance. Alternatively, two pressure sensors may be provided one for each function. The or each pressure sensor can be located adjacent or with either of the other two sensors or remote therefrom. Optionally, the device comprises a body for styling hair, the body having a fluid inlet, a fluid outlet, and a fluid flow path extending between the fluid inlet and the fluid outlet, wherein the fluid outlet is configured to direct the fluid flow stream towards the hybrid sensor. Optionally the device comprises a calibration sensor configured to detect an environmental temperature. Optionally, the hairstyling device may comprise a non-contact temperature sensor, for example a Mid-Infrared (2.5-25pm) sensor. The first sensing element (e.g., temperature sensing element) of the hybrid sensor may comprise the non-contact temperature sensor. Alternatively, the non-contact temperature sensor may be an additional temperature sensor, distinct from the first sensing element. The non-contact temperature sensor may be positioned on the handle or the attachment. As descried above, the controller may be configured to calculate a moisture content value of hair being styled by the hairstyling device based on a measured temperature and humidity of the fluid flow stream detected by the first and second sensor elements, respectively. Accordingly, the hair style device can calculate a moisture content when the motor is generating a fluid flow steam and optionally, when the heater is heating the fluid flow stream. In some examples, the controller may be configured to calculate a moisture content value of the hair when no power is supplied to the heater and / or motor, and thus when there is no (heated) fluid flow stream generated. In these examples, the first sensing element (temperature sensing element) and the second sensing element (humidity sensing element) may be configured to sense a temperature and humidity, respectively, when hair is in proximity to the device (e.g., when hair is wrapped around the attachment of the device or in close proximity to sensing assembly). In these examples, the controller may additionally / alternatively calculate the moisture content value (e.g., hair wetness) based on a measurement detected by the non-contact temperature sensor. For example, the controller may be configured to calculate / estimate an evaporation rate of moisture in the hair using the non-contact temperature sensor, e.g., when no power is supplied to the heater and / or motor. The calculated evaporation rate may then be used in the calculation of the moisture content value of the hair. This may result in more accurate performance of the control function and determine optimal wetness of hair prior styling. The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. Summary of the Figures Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which: Fig. 1 shows an attachment for a hair styling device; Fig. 2A shows an enlarged view of the attachment end of the attachment of Fig. 1; Fig. 2B shows an enlarged view of the tip end of the attachment of Fig. 1; Fig. 3 is an illustration of the aerodynamic effect produced by the attachment of Fig. 1; Fig. 4 shows a hair styling device incorporating an attachment such as that of Fig. 1, the hair styling device incorporating a plurality of hybrid sensors; Fig. 5 is a schematic diagram of a hairstyling device; and Fig. 6 shows a hair styling device for use with an attachment such as that of Fig. 1, the hair styling device incorporating an environmental sensor. Detailed Description of the Invention Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference. An attachment 10 for a hair styling device is described below, with reference to Figs. 1,2A, 2B and 3, where like reference numerals are used to denote features which appear in more than one figure. The attachment 10 comprises an elongate body 1, that extends from a first end, “an attachment end” 3 to a second end “a tip” 2, the attachment end 3 being configured to attach to a handle of a hair styling device, such as those shown in Figs. 3-6. The elongate body comprises a fluid inlet, a fluid outlet and a fluid flow path extending between the fluid inlet and the fluid outlet. At least two elongate plates 12 are mounted on a sub assembly of the elongate body such that they extend in a direction along a longitudinal axis of the elongate body. As shown in Fig. 3, the elongate plates may extend along but also twist around the longitudinal axis of the elongate body. Each of the elongate plates 12 forms a slot between itself and the sub assembly of the elongate body, each slot defining a component of the fluid outlet of the hair styling device. The total fluid output of the device can be understood to be the combination of fluid outputs from all of the plurality of slots. A plurality of fluid outlets may be therefore provided which extend along the elongate member, typically in a twisting configuration. At each of the one or more slots, a plurality of vanes 4 are positioned within the slot and along the slot between the respective elongate plane and the sub-assembly of the elongate body for directing fluid in the fluid flow path towards the fluid outlet. A majority of the plurality of vanes are angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end. In the attachment shown in Fig. 1, more than 80% of the plurality of vanes are angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end. However, it is envisaged that in other embodiments the majority of the plurality of vanes may be more than 50% of the plurality of vanes. A majority of the plurality of vanes may be more than 55%, more preferably more than 60%, more preferably more than 65%, more preferably more than 70%, more preferably more than 75%, more preferably more than 85%, more preferably more than 90%, more preferably more than 95%, of the plurality of vanes. Optionally, all of the plurality of vanes may be angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end. In the attachment shown in Fig. 1, the plurality of vanes 4 are spaced along the length of the elongate body 1. The spacing of the vanes is irregular in that the spacing of the vanes becomes progressively more closely spaced towards the attachment end 3 of the elongate body 1. As depicted in Figs. 2A and 2B, at least some of the plurality of vanes may be angled relative to the longitudinal axis of the elongate body by different amounts to one another. In particular, the angle of at least some of the plurality of vanes may differ from the angle of other vanes (e.g. adjacent vanes). That is to say, the vane angles of the respective vanes vary in magnitude, this variation in magnitude may increase with vane location along the length of the elongate body. Typically, as shown in Fig. 2B, one or more vanes 4a, 4b located at the tip end of the elongate body will be more angled towards the attachment end 3, in that they make a relatively smaller acute angle 14a, 14b with the longitudinal axis 11 in the direction of the attachment end 3 (relative to vanes located at the tip end 2). This relatively smaller acute angle typically has a value of less than 90°, and more than 30°, although as described above, other angles including those of less than 30° are envisaged. As shown in Fig. 2A, one or more vanes 4c located at the attachment end 3 of the elongate body may be angled towards the attachment end 3 by a lesser extent forming a relatively larger acute angle 14c with the elongate axis (compared with those vanes 4a, 4b located at the tip end 2). Alternatively, or additionally one or more vanes 4d at the attachment end 3 of the elongate body may be positioned transverse or substantially transverse to the longitudinal axis of the elongate body such that they are not angled towards the attachment end 2. Alternatively, or additionally, one or more vanes 4e proximate the attachment end 3 may be angled away from the attachment end 3, forming an oblique angle 14e with the longitudinal axis 11 of the elongate body in the direction of the attachment end. By angling the vanes at the tip end 2 the most, and vanes at the attachment end 3 the least, the direction of airflow towards the attachment end 3 will be achieved whilst also improving the wrapping of hair. The greater angle of the vanes 4c, 4d, 4e at the attachment end (e.g. compared to the angle of the vanes 4a, 4b at the tip 2) with the longitudinal axis 11 of the elongate body in the direction of the attachment end 3 helps to keep the wrapped hair on the elongate body 10, ensuring that it does not extend onto the main body 20 (e.g. the handle) of the hairstyling device 30. As depicted in Fig. 3, the purpose of the vanes, and in particular the angling of the vanes is to direct fluid flow 32 towards the attachment end 3 of the attachment 10. This is contrary to the typical fluid flow directions 31 of prior art designs. The directing of fluid flow towards the attachment end of the attachment is advantageous where it is desired to interact with the air flow in some way at the main body, e.g, the handle 20 of a hair styling device 30 which incorporates the attachment. The wrapping of hair depends upon the direction and strength of the fluid flow. Previously, it had been thought that directing fluid around the elongate body lead to the most even wrapping along the elongate body. In fact, as discovered by the present inventors, advantageously, the directing of air towards the attachment end 3 actually leads to an improved wrapping of hair along the length of the elongate body. A hair styling device 40 according to a further aspect of the present invention is now described with reference to Figs. 4 to 6, where like reference numerals correspond to features already described in relation to Figs. 1-3. The hair styling device 40 comprises a plurality of hybrid sensors 43 (although it is envisaged that a single hybrid sensor could be used). Each hybrid sensor 43 comprises a first sensing element 45 configured to sense a temperature of a fluid flow stream 42; and a second sensing element 44 configured to sense a humidity of the fluid flow stream 42. Typically, the fluid flow stream includes water vapour, the humidity and temperature of which is of interest. The one or more hybrid sensors are located on the main body of the hairstyling device, in this case on the handle 21 of the hairstyling device. Where multiple hybrid sensors are present these may be spaced around the circumference of the handle. In the case of the present hair styling device, the hybrid sensors are spaced evenly around the circumference. By colocating multiple sensors on the hair styling device, it is possible to improve signal to noise ratio and reduce the effect from user-based signal disturbance. In alternative examples, the hybrid sensor(s) may be positioned on the attachment of the device. In this particular embodiment, the hybrid sensors are located closer to the attachment end of the handle than the opposing end of the handle. The distance of the hybrid sensors from the attachment portion is typically from 0mm to 1cm, more preferably 0mm to 50mm. In the embodiment shown, one or more of the hybrid sensors are located at a point between the attachment 10 and one or more user interface(s) 49, where the user interface(s) may include buttons, switches and displays such as lights, LEDs, and digital displays. The second sensor may be configured to sense a relative humidity of the fluid flow system where the relative humidity is calculated from the actual vapour pressure and the saturation pressure as set out in equation 1 below. Relative Humidity (%) = ^^^pour pressure x 100 saturation vapour pressure The hair styling device 30, 40, 50 may comprise a hair styling body, which may be an attachment such as the attachment 10 described above. It is envisaged that the attachment may be fixed (e.g., to the main body) in that it forms an integral part of the hairstyling device. Alternatively, it may be removably attachable to the main body 21 of the hairstyling device 30, 40, 50. As depicted in detail in Fig. 5, the main body 21 of the hair styling device 30, 40, 50 comprises a controller 47, typically with a processor and memory. The controller may be configured to calculate a moisture content value of hair being styled by the hair styling device based on a measured temperature and humidity of the fluid flow stream 42 detected by the first and second sensor elements (in this case the temperature sensor 45 and humidity sensor 44), respectively. In some embodiments, the controller is configured to perform a control function based on the calculated moisture content value and that control function may include the steps of: outputting feedback indicating that the calculated moisture content value has met a predefined criterion; adjusting the power supplied to a heater and / or motor of the hair styling device; and / or adjusting a duration of time in which power is supplied to the heater and / or motor (e.g., a styling duration). The control function may include the step of reducing the power supplied to the heater and / or motor of the hair styling device when the calculated moisture content value has met a predefined criterion. In one or more embodiments, an example of which can be seen in Fig. 6, the hairstyling device further includes one or more additional sensors 51. The one or more additional sensors may include a fluid flow sensor and / or a calibration sensor (such as a humidity and / or temperature sensor and / or pressure for measuring environmental conditions for use in calibration). Where an additional sensor functions as a calibration sensor it is advantageous to locate it at the opposite end of the handle from the attachment. In this way, the contribution to heat and / or humidity measurements from the attachment operation may be minimised and the environmental measurement more accurate. Where the one or more additional sensors comprises a fluid flow sensor, the fluid flow sensor may be positioned at the end of the handle adjacent to the attachment and / or on the attachment itself. This may reduce the risk of interference or noise from the user’s hands, for example. In other examples, the fluid flow sensor may be positioned at the opposite end of the handle from the attachment. In some examples, the fluid flow sensor may include a pressure sensor such as a Barometric pressure sensor. The controller may be configured to control the pressure sensor to measure an atmospheric pressure prior to starting the motor and / or heater, and also after starting the motor and / or heater. The controller may be configured to calculate the fluid flow based on the measurements of the atmospheric pressure before and after starting the motor and / or heater. In some examples, the fluid flow sensor may include a proximity sensor such as optical sensor. The controller may be configured to control the sensor to measure target presence / absence prior to starting the motor and / or heater, and also after starting the motor and / or heater. The one or more additional sensors may comprise a non-contact temperature sensor, e.g. a Mid-IR sensor. The non-contact temperature sensor may be positioned on the handle or the attachment. In some examples, the non-contact temperature sensor may be used in a calculation of moisture content value of hair when no power is supplied to the heater and / or motor of the device. For example, the controller may be configured to calculate an evaporation rate of moisture in hair in close proximity to the hairstyling device, and in particular in close proximity to the non-contact temperature sensor, when the heater and / or motor are switched off. This calculated evaporation rate may then be used in the calculation of the moisture content value of the hair. Mechanisms for calibrating and improving upon signals are set out in more detail below. Each could be used alone or in combination. One or more processors located on the hairstyling device may be programmed to carry out the required steps. Environmental Temperature Correction In general, the humidity sensor provides real-time information about the relative humidity in the surrounding gas (air and water vapour mixture), and temperature. In the hair styling device 50, relative humidity and temperature are used to compute mixing ratio or volumetric humidity known more commonly as absolute humidity. The system may require that the temperature recorded corresponds only with the temperature of the gas and only then it allows for accurate measurements of humidity. If the temperature at the sensor location is different from the gas temperature (for example temperature increased due to conductive heat from other product elements such as heater and / or other electronic components) a correction factor may be introduced based on independently measured temperature isolated from conductive heat sources. Other temperature sensors 45 already in use within the system may be used to cross correlate with the temperature response from the humidity sensor to determine the correction factor. Temperature and Humidity Response Time Alignment Humidity sensors 44 measure relative humidity which is temperature dependant. System output is calculated from relative humidity and temperature to determine moisture level that suppresses temperature dependences. An issue may arise during fast transients because the response time for relative humidity and temperature are different. This introduces an error in the computed absolute humidity during these transients. In order to improve performance of the system, the response time of relative humidity and temperature should be aligned such that both signal changes occur at the same time. One or more processors within the heat styling device may be configured to apply the correction. As an example, it may be achieved, but is not limited to, a low-pass filter or varying delay introduced to each measurement before calculating absolute humidity. The response time of the temperature sensor strongly depends on the thermal mass of the sensor module, which is affected by the mounting method. Thermal insulation may advantageously be used while mounting the sensor to the heat styling device. Advantageously, this ensures that the frequency response of the sensor is not significantly affected. System Baseline Correction To correct for the system response and maintain the same output from hair a correction factor that is a function of absolute temperature and relative humidity of the environment may be applied. Environmental information can be extracted from the sensor just after initiating the styling cycle when hair is not present near the attachment. Alternatively, the system can be equipped with a humidity, temperature and / or pressure sensor located near the product inlet or any other location that is decoupled form hair styling signal. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / -10%. 15 04 25

Claims

1. An attachment for a hair styling device, the attachment comprising an elongate body extending from an attachment end to a tip, the attachment end for attaching to a handle of the hair styling device, the elongate body comprising:5 a fluid inlet, a fluid outlet and a fluid flow path extending between the fluid inlet and the fluidoutlet;at least two elongate plates extending in a direction along a longitudinal axis of the elongate body, wherein the at least two elongate plates are mounted on a sub assembly of the elongate body such that each of the plates forms an elongate slot between itself and the sub assembly, each slot defining a10 component of the fluid outlet; anda plurality of vanes for directing fluid in the fluid flow path towards the fluid outlet, wherein the plurality of vanes are positioned along each elongate slot, and wherein a majority of the plurality of vanes are angled relative to the longitudinal axis of the elongate body to direct fluid towards the attachment end;wherein the angle between the longitudinal axis of the elongate body and a vane of the plurality15 of vanes adjacent to the attachment end is greater than the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the tip.

2. An attachment according to claim 1, wherein the plurality of vanes are spaced along the length of the elongate slot.

203. An attachment according to any preceding claim, wherein the angle of the plurality of vanes with respect to the longitudinal axis of the elongate body increases in a direction from the tip to the attachment end.25 4. An attachment according to claim 3, wherein the angles of the plurality of vanes increasesequentially in the direction from the tip to the attachment end.

5. An attachment according to any preceding claim, wherein the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the attachment end is between 60° 30 and 90°.

6. An attachment according to any preceding claim, wherein the angle between the longitudinal axis of the elongate body and a vane of the plurality of vanes adjacent to the tip is less than 30°.

357. An attachment according to any preceding claim, further comprising a hybrid sensor, the hybrid sensor comprising:a first sensing element configured to sense a temperature of a fluid flow stream directed by the plurality of vanes; and40 a second sensing element configured to sense a humidity of the fluid flow stream.15 04 258. An attachment according to claim 7, wherein a plurality of hybrid sensors are provided spaced around the body of the attachment.5 9. A hair styling device comprising the attachment of any preceding claim and a handle, wherein thehandle is configured to be reversibly attachable or permanently attached to the attachment end of the attachment.

10. A hair styling device according to claim 9, further comprising a hybrid sensor, the hybrid sensor10 comprising:a first sensing element configured to sense a temperature of a fluid flow stream directed by the plurality of vanes; anda second sensing element configured to sense a humidity of the fluid flow stream.15 11. A hair styling device according to claim 10, wherein the hybrid sensor is positioned on the handle.

12. A hair styling device according to claim 11, wherein the hybrid sensor is positioned closer to anend of the handle configured to be attached to the attachment than the other opposing end of the handle.20 13. A hairstyling device according to claim 10, wherein the hybrid sensor is positioned within theattachment.

14. A hair styling device according to any one of claims 10-13, further comprising a controller, the controller being configured to calculate a moisture content value of hair being styled by the hairstyling25 device based on a measured temperature and humidity of the fluid flow stream detected by the first and second sensor elements, respectively.

15. A hair styling device according to claim 14, wherein the controller is configured to perform a control function based on the calculated moisture content value.3016. A hair styling device according to claim 15, wherein the control function is: outputting feedback indicating that the calculated moisture content value has met a predefined criterion;adjusting the power supplied to a heater and / or motor of the hairstyling device; and / or35 adjusting a duration of time in which power is supplied to the heater and / or motor.

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