Haircare device

Abstract

A haircare device comprising one or more capacitive sensors is described. Each capacitive sensor includes a structure defining a gap of a predetermined size for receiving a volume of hair. A first electrode and a second electrode are arranged on either side of the gap for performing a capacitive measurement on hair received in the gap.

Description

[0001] HAIRCARE DEVICE

[0002] BACKGROUND

[0003] Various haircare devices such as hairbrushes and hair stylers can be used in combination with the application of heat, in order to style and / or dry hair.

[0004] SUMMARY

[0005] According to a first aspect of the invention, there is provided haircare device comprising one or more capacitive sensors, each capacitive sensor including: a structure defining a gap of a predetermined size for receiving a volume of hair; and a first electrode and a second electrode arranged on either side of the gap for performing a capacitive measurement on hair received in the gap.

[0006] The invention exploits the finding that a capacitive sensor can be used to detect properties of a user’s hair. For example, a capacitive measurement of hair can be used to estimate a moisture content (e.g. ‘wetness’) of the hair. Thus, by incorporating the one or more capacitive sensors in the haircare device, moisture content of the user’s hair can be detected and monitored, for example while the user is drying their hair and / or styling their hair. In this manner, it is possible to avoid over-drying or over-heating the hair, thus reducing risks of hair damage when drying and / or styling hair.

[0007] As the capacitive sensor includes a structure defining a gap of a predetermined size for receiving a volume of hair, capacitive measurements can be performed on a known volume (amount) of hair, which in turn can facilitate determining hair moisture content from the capacitive measurement. In particular, by arranging the capacitive sensor such that capacitive measurements can be performed on a known amount of hair, changes in measured capacitance may result primarily from changes in hair moisture content. In other words, the provision of a structure with a gap for receiving hair can facilitate reliably measuring capacitance across a given amount of hair.

[0008] Thus, in use, the haircare device may be applied to the user’s hair, resulting in some of the user’s hair entering the gap of the capacitive sensor. A capacitive measurement can then be performed on the user’s hair, using the first and second electrodes which are arranged on either side of the gap. For example, an electrical signal can be applied across the first and second electrodes, to measure a capacitance of the hair between the electrodes. In line with the above, the measured capacitance can provide an indication of hair moisture content, e.g. to assist the user when drying and / or styling their hair.

[0009] The gap is shaped for receiving hair. For example, the gap may have an open end (or opening) for receiving hair, and a closed end opposite the open end. In this manner the gap can be filled with hair. Then, performing a capacitive measurement when the gap is filled with hair may yield a reliable indication of hair moisture level.

[0010] The haircare device may be designed to come into contact with hair when in use. For example, the haircare device may comprise a hairbrush, a hair styler, and / or an attachment for a haircare appliance (e.g. a hair dryer).

[0011] For at least one of the one or more capacitive sensors, the gap may be defined between a first member and a second member which protrude from a surface of the haircare device, with the first electrode being on the first member and the second electrode being on the second member. This may facilitate reliably filling the gap with hair in use, which may improve a consistency of capacitive measurements performed with the capacitive sensor. For example, when the user runs the haircare device through (or along) their hair, the first and second members may protrude into the user’s hair, such that the gap between the first and second members can be filled with hair.

[0012] The haircare device may comprise a plurality of bristles for engaging and detangling hair, the first member being a first bristle of the plurality of bristles and the second member being a second bristle of the plurality of bristles. In this manner, the capacitive sensor can be integrated with bristles of the haircare device. Thus, the first bristle and the second bristle can provide two functions, namely engaging and detangling hair, and enabling a capacitive measurement to be performed on hair located in the gap between the first and second bristles. Accordingly, as the plurality of bristles are run through the user’s hair (e.g. to brush their hair), a capacitive measurement can be performed on hair filling the gap between the first bristle and the second bristle.

[0013] The haircare device may comprise a hairbrush, where the plurality of bristles are bristles of the hairbrush. In some cases, the haircare device may comprise a hairbrush attachment for a haircare appliance, where the plurality of bristles are bristles of the hairbrush. The first member and the second member may be formed of a conductive material so as to define the first electrode and the second electrode, respectively. In this manner, a length of the first member which protrudes from the surface of the haircare device can act as the first electrode, and a length the second member which protrudes from the surface of the haircare device can act as the second electrode. This enables capacitance to be measured along a whole height (depth) of the gap, contributing to providing a reliable capacitive measurement. This can also enable a capacitive measurement to be performed even if the gap is not completely filled.

[0014] As an example, where the first member is the first bristle and the second member is the second bristle, the first and second bristles can each comprise a respective wire made of conductive material which protrudes from the surface of the haircare device.

[0015] For at least one of the one or more capacitive sensors, the gap may be defined by a channel (or groove) in a surface of the haircare device. In this manner, hair may readily enter and fill the gap when the haircare device is brought into contact with the user’s hair. The surface in which the channel is defined may be on an outer (external) surface of the haircare device.

[0016] The first electrode and the second electrode may be arranged on opposite sides of the channel, e.g. on opposing sidewalls of the channel.

[0017] The channel may include a first sidewall and a second sidewall which are angled relative to one another such that an opening of the channel is wider than a base of the channel. Such a shape of the channel facilitates guiding hair into the channel, thus facilitating filling the channel with hair. This in turn can facilitate performing a capacitive measurement when the channel is filled with hair, e.g. to provide a reliable indication of hair moisture content.

[0018] The haircare device may comprise a bed and a plurality of bristles that protrude from the bed, the channel being formed in the bed. In this manner, the capacitive sensor can readily be integrated with a device having a plurality of bristles, such as a hairbrush or brush attachment. Thus, when the plurality of bristles are run through the user’s hair, hair can be guided into the channel to enable a capacitive measurement to be performed on the hair. Where the haircare device includes a first member and a second member protruding form a surface as described above, the channel may be defined in the same surface (e.g. the bed). Thus, the haircare device can have a capacitive sensor formed by the protruding members, as well as in the surface of the device.

[0019] The haircare device may comprise a barrel around which hair is wrapped during use, and wherein the channel is formed on an outer surface of the barrel. In this manner, hair can enter the channel when it is wrapped around the barrel, to enable a capacitive measurement to be performed on the hair. Such an arrangement can facilitate filling the channel with hair, such that the capacitive measurement can provide a reliable indication of hair moisture content. As an example, the haircare device may comprise a hair styler having a barrel around which hair is wrapped during use.

[0020] The channel may extend in a direction along which hair is wrapped around the barrel during use. In this manner, the hair may naturally fall into the channel as it is wrapped around the barrel. The channel can also serve to guide wrapping of the hair around the barrel. For instance, the channel may extend in a direction which is at an angle of between 45° and 90° relative to a longitudinal axis of the barrel. This enables the channel to be substantially aligned with hair as it is wrapped around the barrel, thus promoting filling of the channel with hair during use.

[0021] At least one of the one or more capacitive sensors may further comprise a third electrode and a fourth electrode arranged on either side of the gap, the first electrode and second electrode being located closer to a base of the gap and the third electrode and fourth electrode being located closer to an opening of the gap. With such an arrangement of electrodes, it is possible to perform a first capacitive measurement with a first pair of electrodes (i.e. the first and second electrodes) and a second capacitive measurement with a second pair of electrodes (i.e. the third and fourth electrodes). The two capacitive measurements can then be used to determine a filling level of the gap. For example, if hair only partially fills the gap so that the hair reaches the first pair of electrodes but not the second pair of electrodes, only the first capacitive measurement will be affected by the hair in the gap. When the gap is fully filled with hair, both the first capacitive and second capacitive measurement will be affected by the presence of hair in the gap. Thus, it is possible to ensure that the gap is fully filled when using capacitive measurements to determine hair moisture content. Additionally, having two capacitive measurements across the same gap enables the two capacitive measurements to be cross-checked, which may further improve accuracy of the measurement.

[0022] At least one of the one or more capacitive sensors may further comprise a shield electrode for shielding the first and / or second electrode. Such a shield electrode can improve a measurement performance of the capacitive sensor. For example, the shield electrode may serve to shield the capacitive sensor for environmental noise and parasitic capacitances. The shield electrode can be used as an active shield, e.g. by applying a shielding signal to the shield electrode. The shield electrode may take any suitable form. In some implementations, the shield electrode may extend along (adjacent to) the first and / or second electrode. In some cases, the shield electrode may form a loop around the first and / or second electrode.

[0023] For at least one of the one or more capacitive sensors, the structure may be movable to adjust a size of the gap from a first size to the predetermined size. Such an arrangement can facilitate guiding hair into the gap, and increasing a filling factor of the gap. For example, to facilitate receiving hair in the gap, the structure can be moved to make the gap larger. Then, then structure can be moved to return the gap to the predetermined size, which may result in some of the hair being compressed in the gap. As a result, there may be a high filling factor of hair in the gap, which may enhance an accuracy of the capacitive measurement.

[0024] Various mechanisms can be used to adjust the size of the gap, depending on the arrangement of the gap and electrodes. For example, where the electrodes are on the first and second members mentioned above, a mechanism may be provided for adjusting a spacing between the first and second members. Where the gap is defined by a channel in a surface of the device, a mechanism may be provided for adjusting a width and / or depth of the channel.

[0025] The one or more capacitive sensors may comprise a plurality of capacitive sensors. In this manner, multiple capacitive measurements can be performed on the user’s hair. This may enable a more accurate estimate of moisture content to be obtained, e.g. by comparing and / or averaging across the multiple capacitive measurements. The plurality of capacitive sensors may be arranged in a linear array along a surface of the haircare device. In this manner, a plurality of capacitive measurements can be performed on respective samples of hair. Providing a linear array may further increase the likelihood of hair coming into contact with at least one of the capacitive sensors, so that a capacitive measurement of the user’s hair can be obtained even if only part of the haircare device is engaged with the user’ s hair.

[0026] Where the haircare device comprises a plurality of bristles for engaging and detangling hair, the linear array of capacitive sensors may be located between a first set of the plurality bristles and a second set of the plurality of bristles of the plurality of bristles. Such an arrangement may serve to ensure that one or more of the capacitive sensors comes into contact with hair when the plurality of bristles is engaged with the user’s hair. For example, as the haircare device is moved through the user’s hair, hair may extend from the first set of bristles to the second set of bristles, and hence across the linear array of capacitive sensors.

[0027] The plurality of capacitive sensors may comprise a first capacitive sensor and a second capacitive sensor having gaps of different sizes. Using gaps of different sizes may contribute to making the haircare device compatible with a wider variety of different hair types. For example, a smaller gap may readily be filled with straight hair, whereas a larger gap may be more suitable for curly hair. Additionally, by including capacitive sensors with different gap sizes, it is possible to cross-check and validate measurements from the different capacitive sensors, to ensure that they are consistent with one another (e.g. taking into account the different gap sizes). Accordingly, a measurement accuracy can be improved.

[0028] The sizes of the gaps may differ in width and / or height.

[0029] The haircare device may comprise a controller configured to perform a capacitive measurement with each of the one or more capacitive sensors. This may enable the capacitive measurements to be performed automatically by the haircare device. Various suitable capacitive measurement techniques can be implemented by the controller. For example, the controller may be configured to control a measurement signal which is provided to the first and second electrode, and to detect a resulting response signal from the first and second electrodes. The controller can include any suitable processing device or system for controlling the capacitive measurement. The controller can include a processor and a memory storing computer instructions, such that execution by the processor of the computer instructions causes the processor to perform the capacitive measurement.

[0030] For at least one of the one or more capacitive sensors, the controller may be configured to determine a value indicative of a wetness (e.g. moisture content) of hair received in the gap based on the capacitive measurement. In this manner, the wetness of the hair can be automatically determined based on the capacitive measurement. In line with the discussion above, this can facilitate ensuring that the hair is not excessively dried or heated. In order to determine the value indicative of wetness, the controller may store a relationship between results of the capacitive measurement and wetness values. Such a relationship may be obtained, for example, by calibration measurements of the haircare device with hair of different wetness levels.

[0031] The value indicative of wetness of hair can be provided on any suitable scale. In general terms, the value indicative of wetness can be indicative of a moisture (water) content of the hair. Thus the value could, for example, be provided as a wetness “score” (e.g. on a predetermined wetness scale) or as percentage of moisture content (e.g. by weight or volume).

[0032] Where the one or more capacitive sensors comprise a first capacitive sensor and a second capacitive sensor having gaps of different sizes, the controller may be configured to perform a first capacitive measurement with the first capacitive sensor and a second capacitive sensing measurement with the second capacitive sensor, and the controlled is configured to determine a value indicative of a wetness of hair received in the gaps of the first capacitive sensor and the second capacitive sensor based on (e.g. as a function of) the first and second capacitive measurements. In line with the above discussion, taking into account the two capacitive measurements when determining the value indicative of wetness may improve an accuracy of the determination. For example, the wetness values obtained from the two capacitive measurements can be cross-checked against one another, and / or the wetness values obtained from the two capacitive measurements can be averaged.

[0033] In cases where, for at least one of the one or more capacitive sensors, the structure is movable to adjust a size of the gap, the structure may be movable between a first state in which the gap has a first size and a second state in which the gap has the predetermined size, the predetermined size being smaller than the first size; and the controller may be configured to perform a capacitive measurement when the structure is in the second state, and to determine a value indicative of a wetness of hair received in the gap based on the capacitive measurement. Thus, in line with the discussion above, the structure can be moved to the first state for receiving / inserting hair into the gap. Then, the structure can be moved to the second state so that the gap has the predetermined size, to enable accurate determination of the wetness value. Moving of the structure between the first state and the second state may be manually controlled (e.g. by the user), or automatically controlled by the controller.

[0034] The controller may be configured to perform a further capacitive measurement when the structure is in the first state, and to determine the value indicative of the wetness of hair based on (e.g. as a function of) the capacitive measurement and the further capacitive measurement. Use of the capacitive measurement and the further capacitive measurement may contribute to improving an accuracy of the determined wetness value. For example, wetness values obtained from the two capacitive measurements can be cross-checked against one another and / or averaged together.

[0035] The controller may be configured to control the haircare device based on the capacitive measurement. In this manner, the haircare device can be automatically controlled based on the capacitive measurement. For instance, the controller can control the haircare device based on the determined value indicative of hair wetness. Thus, operation of the haircare device can be controlled as a function of hair wetness, such that the haircare device can react substantially in real-time to wetness of the user’s hair.

[0036] By way of example, the controller may be configured to perform one or more of the following based on (i.e. as a function of) the capacitive measurement (or the determined value indicative of wetness): generate an alert, control a temperature of the device, control an airflow of the device, and or switch off the device.

[0037] In the above, various examples of capacitive sensor for the haircare device are described. It is to be understood that a haircare device according to the invention various combinations of the different capacitive sensor types.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic diagram of a haircare device;

[0039] Figure 2 shows a schematic cross-sectional view of a capacitive sensor that may be included in the haircare device of Figure 1;

[0040] Figure 3 shows a schematic cross-sectional view of a capacitive sensor that may be included in the haircare device of Figure 1;

[0041] Figure 4 shows schematic cross-sectional views of a capacitive sensor that may be included in the haircare device of Figure 1;

[0042] Figure 5 shows a schematic cross-sectional view of a shielded electrode that may be included in the haircare device of Figure 1;

[0043] Figure 6 shows a schematic cross-sectional view of the haircare device of Figure 1, including an example arrangement of capacitive sensors;

[0044] Figure 7 shows a schematic cross-sectional view of the haircare device of Figure 1, including an example arrangement of capacitive sensors;

[0045] Figure 8 shows a schematic cross-sectional view of the haircare device of Figure 1, including an example arrangement of capacitive sensors;

[0046] Figure 9 shows schematic cross-sectional views of a capacitive sensor that may be included in the haircare device of Figure 1;

[0047] Figure 10 shows a schematic diagram of a further haircare device; and

[0048] Figure 11 shows a schematic cross-sectional view of a capacitive sensor that may be included in the haircare device of Figure 10.

[0049] DETAILED DESCRIPTION

[0050] Fig. 1 shows a schematic diagram of a haircare device. The haircare device is in the form of a hairbrush 10, which comprises a head 12 connected to a handle 14. The head 12 includes a bed (surface) 16 from which a plurality of bristles 18 protrude. In use, the bristles 18 can serve to engage and detangle hair. The view shown in Fig. 1 corresponds to a top view of the hairbrush 10, i.e. looking towards the hairbrush 10 along a longitudinal direction of the bristles 18. The hairbrush 10 includes one or more capacitive sensors which are configured to perform a capacitive measurement on hair that is engaged with the bristles 18. The capacitive measurement can then be used to provide an indication of wetness (e.g. moisture content) of the hair. Various examples of capacitive sensors that can be included in the hairbrush 10 are described below. In general terms, each capacitive sensor includes a structure defining a gap of a predetermined size for receiving a volume of hair. A first electrode and a second electrode arranged on either side of the gap for performing a capacitive measurement on hair received in the gap. The hairbrush 10 further includes a controller (not shown) which is electrically connected to each of the one or more capacitive sensors and configured to perform a capacitive measurement with each of the one or more capacitive sensors. The controller may be located, for example, in the head 12 or the handle 14 of the hairbrush 10. The hairbrush 10 may further include an internal power source (e.g. battery), and / or an interface for connection to an external power source, in order to power the controller to perform the capacitive measurements.

[0051] In the example shown in Fig. 1, the plurality of bristles 18 includes a first set of bristles 18a and a second set of bristles 18b, which are separated by a gap. A linear array (arrangement) of members 20 is located in the gap between the first set of bristles 18a and the second set of bristles 18b. Each member 20 protrudes from the bed 16, in order to engage the user’s hair during use. The protruding members 20 can serve to define one or more capacitive sensors of the hairbrush 10, as discussed in more detail below.

[0052] Fig. 2 shows a schematic cross-sectional view of a pair of the members 20 of the hairbrush 10, which form a capacitive sensor according to an example. The cross-sectional view of Fig. 2 is taken along a longitudinal axis 22 of the hairbrush, indicated in Fig. 1. The pair of members includes a first member 20a and a second member 20b, which are separated by a gap 24, and which together define a capacitive sensor. The gap 24 has an open end for receiving hair, and a closed end which is defined by the bed 16. Each member 20a, 20b is formed of a flexible material, such as a plastic or rubber material. In some cases, the members 20a, 20b can be formed of a same or similar material as the bristles 18. The first member 20a includes a first electrode 26a which is exposed on a surface of the first member 20a facing towards the gap 24. Likewise, the second member 20b includes a second electrode 26b which is exposed on a surface of the second member 20b facing towards the gap 24. Thus, the first and second electrodes 26a, 26b face each other across the gap 24. For example, the first electrode 26a and the second electrode 26b can be applied to a surface of the first member 20a and the second member 20b, respectively, or partially embedded in a material of the first member 20a and second member 20b, respectively. In some cases, the first member 20a may be formed of a conductive material (e.g. wire), such that the first member 20a itself defines the first electrode. Similarly, the second member 20b may itself be formed of a conductive material (e.g. wire), such that the second member 20b itself defines the second electrode.

[0053] The first electrode 20a and the second electrode 20b are arranged on either side of the gap 24 to perform a capacitive measurement on hair 28 received in the gap 24. In particular, a pair of wires 30a, 30b is provided to connect each of the electrodes to the controller, so that the controller can perform a capacitive measurement with the first and second electrodes 26a, 26b. Thus, for example, the controller can apply a measurement signal (e.g. voltage or current signal) to the first and second electrodes 26a, 26b, in order to perform a capacitive measurement on the hair 28 received in the gap 24. The controller may implement any suitable capacitive measurement protocol for performing a capacitive measurement on the hair 28 in the gap 24. For example, the controller may be configured to transmit a timevarying current to the first and second electrodes 26a, 26b, in order to determine an impedance of the hair 28 in the gap 24.

[0054] When the hairbrush 10 is used to brush hair, hair may enter the gap 24 to fill the space between the first and second electrodes 26a, 26b. In particular, the bristles 18 arranged on either side of the members 20 may serve to guide hair into the gap 24. The controller can then perform a capacitive measurement using the electrodes 26a, 26b, as described above. Wetness (moisture content) of the hair 28 in the gap 24 affects its electrical properties, and will therefore affect the result of the capacitive measurement. Accordingly, the capacitive measurement can be used as an indication of wetness level of hair in the gap 24. The gap 24 has a predetermined (i.e. known) size, such that the capacitive measurement may be performed on a known volume of hair. This facilitates reproducibility of the capacitive measurements, to provide a reliable indicator of hair wetness across multiple measurements.

[0055] Returning to Fig. 1, adjacent pairs of the members 20 may be configured as shown in Fig. 2. Thus, the linear array of members 20 can define a linear array of capacitive sensors, where a respective capacitive measurement can be performed on hair received in the gap of each capacitive sensor. The electrodes in each capacitive sensor can be wired in a similar manner to that shown in Fig. 2, to provide electrical connection to the controller.

[0056] Fig. 3 shows a schematic cross-sectional view of a pair of the members 20 of the hairbrush 10, which form a capacitive sensor according to an example. The cross-sectional view of Fig. 3 is taken along a longitudinal axis 22 of the hairbrush, indicated in Fig. 1. The pair of members includes a first member 20c and a second member 20d, which have a similar constructions to the members 20a, 20b described above. However, whereas each member 20a, 20b includes a single electrode, member 20c and member 20d each include three electrodes. In more detail, multiple pairs of electrodes are provided, to enable capacitive measurements to be performed with different amounts of hair filling the gap 24 between the first and second members 20c, 20d. For example, a first pair of electrodes including a first electrode 32a and a second electrode 32b is located near a base of the gap 24 (i.e. towards the bed 16), the first electrode 32a being provided on the first member 20c and the second electrode 32b being provided on the second member 20d. A second pair of electrodes including a third electrode 32c and a fourth electrode 32d is located further from the base of the gap 24, the third electrode 32c being provided on the first member 20c and the fourth electrode 32d being provided on the second member 20d. Optionally, there can be a third pair of electrodes including a fifth electrode 32e and a sixth electrode 32f located nearer an opening of the gap 24, the fifth electrode 32e being provided on the first member 20c and the sixth electrode 32f being provided on the second member 20d. Thus, the first pair of electrodes 32a, 32b is located nearest that base of the gap 24, the third pair of electrodes 32e, 32f is located nearest the opening of the gap 24 (i.e. towards the tips of the members 20c, 20d), and the second pair of electrodes 32c, 32d is located between the first and third pairs. Each electrode is connected to the controller via a respective wire, to enable the controller to perform a capacitive measurement with each pair of electrodes. Thus, depending on a filling level of the gap 24, one or more of the pairs of electrodes may be used to preform a capacitive measurement on the hair 28. For example, when the gap 24 is completely filled with hair, all three pairs can be used to perform a capacitive measurement on the hair 28 in the gap 24. On the other hand, for a lower level of hair in the gap when the hair only reaches the first pair of electrodes, only the first or second pairs of electrodes may provide a capacitive measurement of the hair. In a similar manner to the discussion above in relation to the capacitive sensor of Fig. 2, the linear array of members 20 in the hairbrush 10 can include one or more capacitive sensors as shown in Fig. 3. In some cases, the linear array of members 20 can include a combination of capacitive sensors according to the examples of Figs. 2 and 3.

[0057] Figs. 4(a) and 4(b) show an example capacitive sensor 40 which may be used in the hairbrush 10, e.g. as part of the linear array of members 20. The capacitive sensor 40 includes a first member 42a and a second member 42b which protrude from the bed 16. In some cases, the first and second members 42a, 42b can correspond to the first and second members 20a, 20b of the capacitive sensor of Fig. 2, or the first and second members 20c, 20d of the capacitive sensor of Fig. 3. In line with the examples provided above, the first member 42a and the second member 42b each comprise or form a respective electrode, for performing a capacitive measurement on hair located between the first and second members 42a, 42b.

[0058] The first member 42a and the second member 42b are movable relative to one another, to vary a width of a gap 44 between the first and second members 42a, 42b. Thus, as shown in Fig. 4(a), when the first and second members 42a, 42b are in a first position, the gap 44 has a first, larger width. From the first position, the first and second members 42a, 42b can be moved towards one another as shown in Fig. 4(b), so that the gap 44 has a second, smaller width. As an example, in use the first and second members 42a, 42b may initially be in the first position shown in Fig. 4(a). This may facilitate receiving hair 28 in the gap 44, due to the larger width of the gap in this position. Then, the first and second members 42a, 42b can be moved to the second position shown in Fig. 4(b). This may compress the hair 28 as well as distribute the hair along a height of the gap, which may ensure a better coverage of the electrodes on the first and second members 42a, 42b. This can also ensure that the hair is held in place between the first and second members 42a, 42b while performing a capacitive measurement. Accordingly, the first and second members 42a, 42b can be moved to the second position (Fig. 4(b)) to perform a capacitive measurement on the hair 28, as this may improve a reliability and reproducibility of the measurement. Additionally, a capacitive measurement can also be performed in the first position (Fig. 4(a)), which may serve to provide information about a filling level of the gap 44 and / or serve to validate or cross-check a measurement performed in the second position. Any suitable mechanism can be used to enable relative movement between the first member 42a and the second member 42b. For example, the bed 16 may comprise a flexible (deformable) material, and an actuator may be provided to compress the bed 16 in order to move the first and second members 42a, 42b towards one another. The actuator may be controlled manually (e.g. by a user), or automatically by the controller.

[0059] Fig. 5 shows a schematic diagram of one of the members 20 of the hairbrush 10 which includes a shield electrode 50. The shield electrode 50 extends from the bed 16 to form a loop around the member 20. In use, the shield electrode 50 serves to shield the member 20 from stray signals and parasitic capacitance, to improve a quality of a capacitive measurement performed with the member. The shield electrode 50 can be electrically connected to the controller of the hairbrush 10, so that an active shielding signal can be provided to the shielding electrode 50 during use. Such a shielding electrode may be provided in the examples of capacitive sensors described above. For instance, such a shielding electrode may be provided around one or both of the members of the capacitive sensors described in relation to Figs. 2-4.

[0060] In the above, capacitive sensors for the hairbrush 10 have been described in relation to the array of members 20. However, other locations and types of capacitive sensors may also be used. For example, additionally or alternatively to providing one or more capacitive sensors in the array of members 20, one or more capacitive sensors can be implemented in the plurality of bristles 18. For instance, a pair of the bristles 18 could be provided with one or more pairs of electrodes to form a capacitive sensor. In particular, the examples of capacitive sensors described above in relation to Figs. 2-5 could be implemented in an analogous manner using pairs of bristles 18 instead of pairs of members 20. Thus, a bristle 18 could be formed of an electrically conductive material so as to form an electrode, or an electrode could be provided on (or partially embedded) in a bristle 18, such that pairs of bristles can be used to form a capacitive sensor. In some cases, where one or more capacitive sensors are provided in the bristles 18, the array of members 20 need not be provided. In some cases, there may be a combination of one or more capacitive sensors in the linear array of members 20, and one or more capacitive sensors in the plurality of bristles 18. In some examples, a pair of members 52a, 52b may protrude from a side of the brush head 12, as shown in Fig. 1. The pair of members 52a, 52b may be used to provide a capacitive sensor, alternatively or in addition to the previous examples of capacitive sensor described for the hairbrush 10. The pair of members 52a, 52b may, for example, be configured in an analogous manner to any of the capacitive sensors described above in relation to Figs. 2-5.

[0061] Fig. 6 shows a schematic cross-sectional view of an example implementation of the hairbrush 10. In this example, four capacitive sensors 60a, 60b, 60c, 60d are formed by adjacent pairs of the members 20 in the linear array. As can be seen, the capacitive sensors 60a, 60b, 60c, 60d have different heights, meaning that they can receive different amounts of hair. In particular, members 20 of different heights are used for defining the gaps of the various capacitive sensors 60a, 60b, 60c, 60d. Thus, for example, the gap between the members 20 forming the capacitive sensor 60a has a smaller height compared to the gap between the members 20 forming the capacitive sensor 60c. In this manner, the capacitive sensors 60a, 60b, 60c, 60d can be used to perform capacitive measurements on different amounts of hair. Such a variety of sensor size can improve an accuracy with which hair wetness can be determined, for example by using measurements from the different sensors to cross-check and validate a determined wetness value, and / or by averaging values from the different measurements together.

[0062] Fig. 7 shows a schematic cross-sectional view of an example implementation of the hairbrush 10. In this example, four capacitive sensors 70a, 70b, 70c, 70d are formed by adjacent pairs of the members 20 in the linear array. As can be seen, the capacitive sensors 70a, 70b, 70c, 70d have different widths, meaning that they can receive different amounts of hair. In particular, different spacings between pairs of members 20 for the various capacitive sensors 70a, 70b, 70c, 70d, resulting in gaps of different widths for the sensors. Thus, for example, the gap between the members 20 forming the capacitive sensor 70a has a smaller width compared to the gap between the members 20 forming the capacitive sensor 70b. In this manner, the capacitive sensors 70a, 70b, 70c, 70d can be used to perform capacitive measurements on different amounts of hair. Such a variety of sensor size can improve an accuracy with which hair wetness can be determined, for example by using measurements from the different sensors to cross-check and validate a determined wetness value, and / or by averaging values from the different measurements together. Fig. 8 shows a schematic cross-sectional view of another example implementation of the hairbrush 10. In this example, a plurality of channels 80 (or grooves) are formed in the bed 16 of the hairbrush 10. The channels 80 can extend between the bristles 18 and / or the members 20. For illustration purposes, the channels 80 are not shown in Fig. 1. Each channel 80 is configured to receive an amount of hair during use. In particular, each channel 80 has a tapered shape with a wide opening that tapers towards its base, to facilitate receiving of hair in the channel 80. Each channel 80 is provided with a first electrode 82a and a second electrode 82b which are exposed on opposing sidewalls of the channel. Thus, the first electrode 82a and the second electrode 82b face each other across a gap defined by the channel. Each of the first and second electrodes 82a, 82b is electrically connected to the controller via a respective wire (not shown). In this manner, the first electrode 82a and the second electrode 82b can be used to perform a capacitive measurement on hair received in the channel 80, in a similar manner to that described above. Accordingly, each channel 80 and set of electrodes 82a, 82b forms a capacitive sensor. Such a capacitive sensor may be provided alternatively or in addition to the other types of capacitive sensor described above.

[0063] In some examples, a size (e.g. width) of the channel 80 is adjustable, as shown in Figs. 9(a) and 9(b). In particular, opposing sidewalls of the channel 80 may be movable relative to one another in order to vary a size of the channel 80, and hence a spacing between the electrodes 82a, 82b. The sidewalls of the channel 80 may be movable between a first position shown in Fig. 9(a) where an opening angle between the sidewalls is larger (i.e. where a spacing between the electrodes 82a, 82b is larger), and a second position shown in Fig. 9(b) where the opening angle between the sidewalls is smaller (i.e. where the spacing between the electrodes 82a, 82b is smaller). As an example, in use the sidewalls of the channel 80 may initially be in the first position shown in Fig. 9(a). This may facilitate receiving hair 28 in the channel 80, due to the larger opening angle of the channel 80 in this position. Then, the sidewalls of the channel 80 can be moved to the second position shown in Fig. 9(b). This may compress the hair 28 in the channel 80 as well as distribute the hair along a height of the channel 80, which may provide a better coverage of the electrodes 82a, 82b. This can also ensure that the hair is held in place between the first and second electrodes 82a, 82b while performing a capacitive measurement. Accordingly, the sidewalls of the channel 80 can be moved to the second position (Fig. 9(b)) to perform a capacitive measurement on the hair 28, as this may improve a reliability and reproducibility of the measurement. Additionally, a capacitive measurement can also be performed in the first position (Fig. 9(a)), which may serve to provide information about a filling level of the channel 80 and / or serve to validate or cross-check a measurement performed in the second position.

[0064] Any suitable mechanism can be used to enable the size of the channel 80 to be adjusted. For example, the bed 16 may comprise a flexible (deformable) material, and an actuator may be provided to compress the bed 16 in order to move the sidewalls of the channel 80 towards one another. The actuator may be controlled manually (e.g. by a user), or automatically by the controller.

[0065] It should be noted that one or more of the various capacitive sensor designs described above in relation to Figs. 2-9 can be incorporated into the hairbrush 10.

[0066] Fig. 10 shows a schematic diagram of a further haircare device 100. The haircare device 100 includes a handle 102 from which a barrel 104 extends. During use, hair is wrapped around the barrel 104, e.g. to dry and / or style the hair. For example, the device 100 may be configured to heat hair wrapped around the barrel 104 and / or direct an airflow onto hair wrapped around the barrel 104.

[0067] The barrel 104 includes a plurality of channels (or grooves) 106 which are provided on an outer surface of the barrel 104. In particular, as shown in Fig. 10, a series of ridges 108 are arranged on the outer surface of the barrel 104 to define the channels 106. Each channel 106 is formed between a sidewall of one of the ridges 108 and the outer surface of the barrel 104. An expanded cross-sectional view of one of the channels 106 is shown in Fig. 11. In other examples, the channels 106 may be formed in a different manner on the barrel 104. For instance, the channels 106 may be in the form of grooves provided directly in the outer surface of the barrel 104 (e.g. without a need for providing ridges). The channels 106 are arranged to receive hair during use, i.e. when hair is wrapped around the barrel 104. In particular, the channels are oriented so that they extend along a direction in which hair is wrapped around the barrel 104. For example, the channels 106 can extend in a direction which is at an angle between 45° and 90° relative to a longitudinal axis 110 of the barrel 104. As shown in Fig. 11, each channel 106 includes a first electrode 112a and a second electrode 112b, which are exposed on opposing sidewalls of the channel 106. For example, the first electrode 112a can be provided on a sidewall of the ridge 108, and the second electrode 112b can be provided on an adjacent outer surface of the barrel 104. Each electrode is electrically connected to a controller of the device 100. Thus, the channel 106 and electrodes 112a, 112b form a capacitive sensor for performing a capacitive measurement on hair 28 located in the channel 106. The controller of the device 100 may, for example, be located in the handle 102. The controller of the device 100 can be configured in an analogous manner to the controller of the hairbrush 10 described above, to perform capacitive measurements on hair located in the channels 106. The device 100 may further include an internal power source (e.g. battery), and / or an interface for connection to an external power source, in order to power the controller to perform the capacitive measurements.

[0068] The controller of the hairbrush 10 or of the device 100 can be configured to determine (e.g. calculate) a value indicative of wetness of the user’s hair based on (i.e. as a function of) the capacitive measurements. For example, the controller may use a predetermined relationship between an output of the capacitive measurement and a wetness value of the hair, to determine the value indicative of wetness. Such a relationship may be determined based on calibration measurements, e.g. by performing capacitive measurements with hair of different wetness levels. Where the hairbrush 10 includes different arrangements of capacitive sensor, e.g. as shown in Figs. 6 and 7, the controller may use a respective predetermined relationship for each different sensor arrangement. In this manner, a wetness value can be determined from each capacitive sensor arrangement, such that the wetness values can be cross-checked against one another and / or averaged together. Likewise, where a size of the gap of the capacitive sensor is adjustable (e.g. as described in relation to Figs. 4(a), 4(b) and Figs. 9(a), 9(b)), the controller may use predetermined relationships for different gap sizes, to determine wetness values based on measurements performed with different gap sizes.

[0069] In some cases, the controller can be configured to control the device (e.g. the hairbrush 10 or the device 100) based on a wetness value determined from the capacitive measurements. Different types of control may be performed. For example, the controller may be configured to generate an alert, e.g. to notify the user that a particular level of hair wetness (dryness) has been reached. As another example, the controller may be configured to use the determined wetness value as an input in a control loop for controlling an output of the device, such as a temperature of the device and / or airflow of the device.

Claims

CLAIMS1. A haircare device comprising one or more capacitive sensors, each capacitive sensor including: a structure defining a gap of a predetermined size for receiving a volume of hair; and a first electrode and a second electrode arranged on either side of the gap for performing a capacitive measurement on hair received in the gap.

2. A haircare device according to claim 1 wherein, for at least one of the one or more capacitive sensors, the gap is defined between a first member and a second member which protrude from a surface of the haircare device, and wherein the first electrode is on the first member and the second electrode is on the second member.

3. A haircare device according to claim 2, wherein the haircare device comprises a plurality of bristles for engaging and detangling hair, and wherein the first member is a first bristle of the plurality of bristles and the second member is a second bristle of the plurality of bristles.

4. A haircare device according to claim 2 or 3, wherein the first member and the second member are formed of a conductive material so as to define the first electrode and the second electrode, respectively.

5. A haircare device according to any preceding claim, wherein, for at least one of the one or more capacitive sensors, the gap is defined by a channel in a surface of the haircare device.

6. A haircare device according to claim 5, wherein the channel includes a first sidewall and a second sidewall which are angled relative to one another such that an opening of the channel is wider than a base of the channel.

7. A haircare device according to claim 5 or 6, wherein the haircare device comprises a bed and a plurality of bristles that protrude from the bed, and wherein the channel is formed in the bed.

8. A haircare device according to claim 5 or 6, wherein the haircare device comprises a barrel around which hair is wrapped during use, and wherein the channel is formed on an outer surface of the barrel; and optionally wherein the channel extends in a direction which is at an angle of between 45° and 90° relative to a longitudinal axis of the barrel.

9. A haircare device according to any preceding claim, wherein at least one of the one or more capacitive sensors further comprises a third electrode and a fourth electrode arranged on either side of the gap, and wherein the first electrode and second electrode are located closer to a base of the gap and the third electrode and fourth electrode are located closer to an opening of the gap.

10. A haircare device according to any preceding claim, wherein at least one of the one or more capacitive sensors further comprises a shield electrode for shielding the first and / or second electrode.

11. A haircare device according to any preceding claim wherein, for at least one of the one or more capacitive sensors, the structure is movable to adjust a size of the gap from a first size to the predetermined size.

12. A haircare device according to any preceding claim, wherein the one or more capacitive sensors comprises a plurality of capacitive sensors.

13. A haircare device according to claim 12, wherein the plurality of capacitive sensors is arranged in a linear array along a surface of the haircare device; and optionally wherein the haircare device comprises a plurality of bristles for engaging and detangling hair, and the linear array of capacitive sensors is located between a first set ofthe plurality of bristles and a second set of the plurality of bristles of the plurality of bristles.

14. A haircare device according to claim 12 or 13, wherein the plurality of capacitive sensors comprises a first capacitive sensor and a second capacitive sensor having gaps of different sizes; and optionally wherein the sizes of the gaps differ in width and / or height.

15. A haircare device according to any preceding claim, wherein the haircare device comprises a controller configured to perform a capacitive measurement with each of the one or more capacitive sensors.

16. A haircare device according to claim 15 wherein, for at least one of the one or more capacitive sensors, the controller is configured to determine a value indicative of a wetness of hair received in the gap based on the capacitive measurement.

17. A haircare device according to claim 15 or 16, wherein the one or more capacitive sensors comprise a first capacitive sensor and a second capacitive sensor having gaps of different sizes, the controller is configured to perform a first capacitive measurement with the first capacitive sensor and a second capacitive measurement with the second capacitive sensor, and the controlled is configured to determine a value indicative of a wetness of hair received in the gaps of the first capacitive sensor and the second capacitive sensor based on the first and second capacitive measurements.

18. A haircare device according to claim 15, wherein, for at least one of the one or more capacitive sensors, the structure is movable to adjust a size of the gap, and wherein: the structure is movable between a first state in which the gap has a first size and a second state in which the gap has the predetermined size, the predetermined size being smaller than the first size; and the controller is configured to perform a capacitive measurement when the structure is in the second state, and to determine a value indicative of a wetness of hair received in the gap based on the capacitive measurement.

19. A haircare device according to claim 18, wherein the controller is configured to perform a further capacitive measurement when the structure is in the first state, and to determine the value indicative of the wetness of hair based on the capacitive measurement and the further capacitive measurement.

20. A haircare device according to one of claims 15 to 19, wherein the controller is configured to control the haircare device based on the capacitive measurement.

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