Haircare device

Abstract

A haircare device is disclosed. The haircare device comprises one or more pairs of plates, each pair of plates comprising a respective first plate and second plate which are mutually opposed. A heater arranged is to heat at least one of the first plate and the second plate in each pair of plates. Each pair of plates is arranged to define a respective channel for receiving hair, each pair of plates being movable to vary a width of the respective channel. A spring arrangement is configured to provide a clamping force to resist a movement of the first plate and the second plate away from one another. The spring arrangement provides different spring rates in different portions of the movement.

Description

1 P005844-W001HAIRCARE DEVICEBACKGROUND

[0001] Haircare appliances are known for styling hair. Some haircare appliances (e.g. hair straighteners) include arms, between which hair to be styled can be clamped. In some cases, heat can be used to facilitate shaping of hair clamped between the arms.SUMMARY

[0002] In an aspect, there is provided a haircare device comprising: one or more pairs of plates, each pair of plates comprising a respective first plate and second plate which are mutually opposed; a heater arranged to heat at least one of the first plate and the second plate in each pair of plates; and a spring arrangement; wherein each pair of plates is arranged to define a respective channel for receiving hair, each pair of plates being movable to vary a width of the respective channel; wherein, for each pair of plates, the spring arrangement is configured to provide a clamping force to resist a movement of the first plate and the second plate away from one another, the spring arrangement being configured to provide a first spring rate in a first portion of the movement where the first plate and the second plate are closer to one another, and to provide a second, different spring rate in a second portion of the movement the first plate and the second plate are further from one another, such that the clamping force is greater in the second portion of the movement than in the first portion of the movement.

[0003] In this manner, the spring arrangement provides different spring rates in different portions of the movement of the first and second plates away from one another. In other words, the spring rate of the spring arrangement varies as a function of the separation of the first plate and the second plate.

[0004] The varying spring rate of the spring arrangement is configured such that there is a lower clamping force between the plates in the first portion of the movement (i.e. when the plates are closer together), and a higher clamping force between the plates in the second portion of the movement (i.e. when the plates are further apart). The lower clamping force in the first portion of the movement may avoid snagging (catching) of strands of hair between the plates, e.g. as the end of a tress is pulled through the plates. This facilitates pulling hair through the channel between the plates. When the plates are further apart and a larger volume2 P005844-W001 of hair is disposed between the plates, a greater clamping force is applied on the hair. This may promote effective transfer of heat from the plates to the hair, and improve a styling performance of the plates on the hair. Accordingly, the varying spring rate enables strong clamping of hair in the second portion of the movement to promote effective treatment of the hair, whilst providing a smaller clamping force in the first portion of the movement to facilitate removing (e.g. pulling out) smaller strands of hair from between the plates. By providing a spring rate that changes between the first and second portions of the movement, it is possible to individually tailor a profile of the clamping force in each of the first and second portions of the movement, e.g. to facilitate removal of the hair in the first portion and to promote heat transfer and styling of the hair in the second portion.

[0005] Herein, the first portion of the movement may refer to a first range of distance (separation) between the first and second plate, and the second portion of the movement may refer to a second (different) range of distance (separation) between the first and second plate.

[0006] Herein, a spring arrangement may refer to an arrangement of one or more springs. A spring rate provided by the spring arrangement may therefore refer to a combined (or effective) spring rate of the one or more springs. Any suitable type of spring may be used in the spring arrangement.

[0007] The spring arrangement can include one or more of a coil spring, a conical spring, a leaf spring, and a resilient material (e.g. an elastomeric material such as rubber or silicone).

[0008] The first spring rate may be constant across the first portion of the movement, and / or the second spring rate may be constant across the second portion of the movement.

[0009] The first spring rate may be non-constant (e.g. variable) across the first portion of the movement, and / or the second spring rate may be non-constant across the second portion of the movement.

[0010] The one or more pairs of plates may comprise a plurality of pairs of plates.

[0011] The width of the channel for each pair of plates may correspond to a distance between a portion of the first plate and a portion of the second plate. The distance between the portion of the first plate and the portion of the second plate is greater in the second portion of the movement than in the first portion of the movement. The portion of the first plate and the portion of the second plate may oppose one another across the channel.3 P005844-W001

[0012] In some cases, the width of the channel for each pair of plates may be uniform, e.g. along one or more dimensions of the channel. Alternatively, the width of the channel may vary along one or more dimensions of the channel.

[0013] For each pair of plates, the width of the channel may vary in a uniform or non- uniform manner when the plates are moved away from one another.

[0014] The haircare device may comprise a body (e.g. housing) from which the one or more plates protrude. The heater may be disposed in the body. The body may comprise (or be connected to) a handle for holding the haircare device. Other features of the device, such as a power source and control electronics may be disposed in the body of the haircare device.

[0015] Each pair of plates may be movable between a closed position where the first plate and the second plate contact one another, and an open position where the first plate and the second plate are spaced apart. The spring arrangement may be configured to press the first plate against the second plate in the closed position. Thus, the channel may be closed when the pair of plates is in the closed position. Accordingly, a non-zero force may be exerted by the spring arrangement when the plates are in the closed position to press the plates together. This may ensure that even small volumes of hair can be clamped between the pair of plates. Moreover, as the spring arrangement presses the first plate against the second plate, this promotes transmission of heat between the two plates in the closed position, which may enhance distribution of heat across the two plates. The force exerted by the spring arrangement may further avoid or reduce play between the first and second plates in the closed position, which may avoid rattling of the plates.

[0016] The spring arrangement may bias the first plate and the second plate towards the closed position.

[0017] For each pair of plates, the heater may be arranged to heat one of the first plate and the second plate. For example, the heater may be (permanently) thermally coupled to one of the first plate and the second plate, i.e. regardless of a relative position of the first plate and the second plate. Then, when the pair of plates is in the closed position, heat may be transferred, via the one of the first and second plates, to the other one of the first and the second plates. In this manner, the heater need only be coupled to one plate in each pair. For example, the heater may be coupled to a static plate in each pair, which may simplify a construction of the haircare device.4 P005844-W001

[0018] The heater may comprise one or more heaters. Where multiple heaters are used, these may be arranged to heat respective portions of the plurality of plates. This may facilitate obtaining a desired heating profile across the plurality of plates.

[0019] Various heater arrangements can be used. As an example, the plurality of pairs of plates may be disposed (e.g. mounted) on a base. The one or more heaters may then be thermally coupled to the base, so that heat is conveyed from the one or more heaters to the plurality of pairs of plates via the base. In some cases, one or more of the heaters may be disposed in the plurality of pairs of plates, e.g. for one or more of the pairs of plates, a heater may be disposed in the first plate and / or the second plate. For each pair of plates, the first plate or the second plate may be fixed (e.g. relative to the base). In such a case, a heater may be disposed in the fixed plate.

[0020] The spring arrangement may be configured to provide a maximum clamping force of 2.5 N or less in the first portion of the movement. It has been found that a clamping force in this range reduces user discomfort when pulling a tress of hair through the channel.

[0021] In some cases, the maximum clamping force may be 0.25 N or less in the first portion of the movement. Such a clamping force may be low enough so as to prevent snagging (e.g. catching) of strands of hair when they pulled out of the channel. This reduces user discomfort when pulling one or two individual hairs through the channel, which facilitates comfortable operation with reduced user concentration.

[0022] A maximum separation between the first plate and the second plate in the first portion of the movement may be 0.6 mm or less. In other words, the spring arrangement may provide the first spring rate and lower clamping force up to the maximum separation. Thus, in the first portion of movement, the plates may be separated at most by a distance of 0.6 mm. So, a maximum width of the channel may be less than 0.6 mm or less in the first portion of the movement. In this manner, only a small amount of hair may fit in the channel in the first portion of the movement, such that the lower clamping force is only applied when a small amount of hair is in the channel.

[0023] In some cases, the maximum separation between the first plate and the second plate in the first portion of the movement may be between 0.05 mm and 0.3 mm. In this manner, only one or a small number of strands of hair may fit in the channel in the first portion of the movement. Accordingly, the lower clamping force is applied only when a small number of hairs can be located in the channel. This avoids snagging of individual strands (or small5 P005844-W001 numbers of strands) between the plates, whilst ensuring that the larger clamping force is applied when larger volumes of hair are inserted between the plates.

[0024] Each pair of plates may be independently movable to vary the width of the respective channel. The spring arrangement may comprise a respective spring arrangement for each pair of plates. By making each pair of plates independently movable, the width of each channel may vary in accordance with a size of the portion of hair received in each channel. Accordingly, a clamping force may be exerted on hair portions received between each pair of plates, regardless of differences in size of the various hair portions. The clamping force exerted on hair received in the channel between each pair of plates may promote effective transfer of heat from the plates to the hair. The clamping force may also allow the user to tension their hair, which may facilitate styling of the hair.

[0025] Each respective spring arrangement may have any of the features described herein with respect to the spring arrangement.

[0026] The first spring rate may be lower than the second spring rate. In this manner, the clamping force may ramp more slowly as the plates are moved apart in the first portion of the movement. This may ensure that the clamping force remains relatively low in the first portion of the movement, to avoid hair snagging and facilitate removal of hair strands from between the plates. The higher second spring rate may result in a more rapid ramping up of the clamping force as the plates are separated in the second portion of the movement, contributing to more effective treatment (e.g. heating, tensioning) of the hair between the plates.

[0027] The spring arrangement may comprise a spring having a variable spring rate. In this manner, a single spring can be used to provide both the first spring rate and the second spring rate. This may contribute to simplifying a construction and reducing a number of components in the haircare device, as well as making the device more compact.

[0028] The spring arrangement may comprise a first spring portion configured to provide the first spring rate in the first portion of the movement, and a second spring portion configured to provide the second spring rate in the second portion of the movement. Accordingly, separate spring portions may be arranged to provide the different spring rates. This may facilitate obtaining different desired spring rates in each portion of the movement, and tailoring the spring rate in each portion of the movement to provide a desired effect. The6 P005844-W001 first spring portion may comprise a first spring, and the second spring portion may comprise a second spring.

[0029] The first spring portion may be configured to engage a first engagement surface to provide a first force urging the first plate and the second plate towards one another. The second spring portion may be configured to engage a second engagement surface to provide a second force urging the first plate and the second plate towards one another. The second spring portion may be disengaged from the second engagement surface in the first portion of the movement. Thus, in the first portion of the movement, there may be a clearance between the second spring portion and the second engagement surface, such that the second spring portion does not contribute to the total clamping force provided by the spring arrangement. In this manner, only the first spring portion may contribute to the clamping force in the first portion of the movement. In the second portion of the movement, the second spring portion engages the second engagement surface to contribute to the clamping force. The first spring portion may remain engaged with the first engagement surface in the second portion of the movement, in which case both the first and second spring portions may contribute to the total clamping force.

[0030] The first engagement surface may be provided on the first plate or the second plate. The second engagement surface may be provided on the first plate or the second plate.

[0031] The first spring portion may comprise a cantilever. Advantageously, a cantilever provides a compact spring portion for applying a clamping force, e.g. as compared to other spring types such as a coil spring, thus contributing to reducing a size of the spring arrangement. The cantilever may correspond to a flexible beam which is free at one end, e.g. such that deflection of the free end results in an opposing force.

[0032] The cantilever may be formed of a (substantially) flat spring material, such as metal. This may enhance a compactness of the cantilever.

[0033] The second spring portion may comprise a leaf spring. A leaf spring may typically have a (substantially) flat shape, thus contributing to reducing a size of the spring arrangement and enhancing a compactness of the haircare device. The leaf spring may comprise a leaf (or plate) which is supported at opposing ends. A deformation applied to a central region of the leaf spring results in an opposing force.

[0034] The first spring portion and the second spring portion may be integrally formed as a single part. In other words, the first spring portion and the second spring portion may7 P005844-W001 correspond to respective portions of a same (unitary) component. This may simplify construction of the haircare device, as the spring arrangement may be provided as a single component.

[0035] For example, the first spring portion and the second spring portion may correspond to respective portions of a spring material.

[0036] Where the first spring portion comprises a cantilever and the second spring portion is a leaf spring, the cantilever and the leaf spring may correspond to respective portions of a same piece of spring material. For instance, the cantilever may extend from an end (or edge) of the leaf spring. As an example, a plate of spring material (e.g. metal spring plate) may be cut to define a first portion corresponding to the cantilever and a second portion corresponding to the leaf spring.

[0037] For a first one of the one or more pairs of plates, the spring arrangement may be connected between the first plate of the first pair of plates and the second plate of an adjacent one of the one or more pairs of plates. In this manner, the spring arrangement may be located in a space between adjacent pairs of plates, which may contribute to making the haircare device more compact. Moreover, this may facilitate making each pair of plates individually sprung, as the spring arrangement for each pair of plates may be located in a gap between that pair of plates and an adjacent pair of plates.

[0038] The spring arrangement may comprise a first spring element configured to provide a first force urging the first plate and the second plate towards one another, and a second spring element configured to provide a second force opposing the first force in only the first portion of the movement. In this manner, the opposing second force provided by second spring element reduces the total clamping force provided by the spring arrangement in the first portion of the movement. In contrast, the second spring element does not provide an opposing force in the second portion of the movement, resulting in a higher total clamping force provided by the spring arrangement in the second portion of the movement.

[0039] As an example, the second spring element may be arranged in the first portion of the movement to apply the second force to an engagement surface. In the second portion of the movement, the second spring portion may be disengaged from the engagement surface, so that the second force is no longer applied.8 P005844-W001

[0040] The second spring portion may have a higher spring rate than the first spring portion. The second spring portion may be arranged to be in a compressed state in the first portion of the movement.

[0041] For each pair of plates, the second spring portion may be arranged to be compressed between the first plate and the second plate in the first portion of the movement. In this manner, when the second spring portion is compressed between the first and second plates, the second spring portion may urge the plates apart, thus opposing the first force provided by the first portion of the spring.

[0042] As an example, the second portion of the spring may comprise an elastomeric material (e.g. silicone) provided on a surface of the first plate and / or the second plate in the channel, such that the elastomeric material is compressed between the plates in the first portion of the movement.BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Fig. 1 shows a perspective view of a haircare device.

[0044] Fig. 2 shows a cross-sectional diagram of the haircare device.

[0045] Fig. 3 shows a perspective view of a plurality of pairs of plates of the haircare device.

[0046] Fig. 4 shows a cross-sectional view of the plurality of pairs of plates.

[0047] Fig. 5 shows a side view of an array of static second plates from the plurality of pairs of plates.

[0048] Fig. 6 shows a plan view of a spring arrangement from the haircare device.

[0049] Fig. 7 shows a plan view of a first plate including the spring arrangement.

[0050] Fig. 8 shows a side view of a first pair of plates of the haircare device in a closed position.

[0051] Figs. 9a and 9b show cross-sectional views of the first pair of plates in the closed position.

[0052] Fig. 10 shows a side view of the first pair of plates in an open position.

[0053] Figs. I la and 11b show cross-sectional views of the first pair of plates in the open position.

[0054] Fig. 12 shows a graph of a clamping force for a pair of plates as a function of displacement between the pair of plates.9 P005844-W001

[0055] Figs. 13a and 13b show side views of a pair of plates for a haircare device in a closed position and open position, respectively.

[0056] Fig. 14a shows a graph of forces exerted by a first spring element and a second spring element in the pair of plates of Figs. 13a and 13b.

[0057] Fig. 14b shows a graph of a clamping force resulting from the first spring element and the second spring element.DETAILED DESCRIPTION

[0058] A haircare device 10 is described with reference to Figs. 1 to 11. Fig. 1 shows a perspective view of the haircare device 10, and Fig. 2 shows a cross-sectional view taken along a longitudinal axis of the haircare device 10. The haircare device 10 comprises a body having a head portion 12 and a handle portion 14 connected to the head portion 12.

[0059] The head portion 12 of the haircare device 10 comprises a plurality of pairs of plates 16 arranged in a row extending in a longitudinal direction of the haircare device 10. A perspective view of the plurality of pairs of plates 16 on their own is shown in Fig. 3, whilst Fig. 4 shows a cross-sectional view of the plurality of pairs of plates 16 on their own, the cross-sectional view of Fig. 4 being in the same plane as the view of Fig. 2. The example shown includes 14 pairs of plates, however other examples may include different numbers of pairs of plates.

[0060] Each pair of plates includes a first plate 18a and a second plate 18b which are mutually opposed so as to define a channel for receiving hair therebetween. The second plate 18b has a fixed position, and the first plate 18a is movable relative to the second plate 18a between an open position and a closed position. In the open position, the plates 18a, 18b are spaced apart, whereas in the closed position the plates 18a, 18b contact one another to close the channel. In Fig. 4, each of the pairs of plates 16 is in the closed position, with the first plate 18a and the second plate 18b of each pair contacting one another so as to close the channel therebetween.

[0061] Each pair of plates further includes a respective spring arrangement (which may also be referred to as a biasing member) 20 which is arranged to urge the first plate 18a towards the second plate 18b, i.e. so that the plates 18a, 18b are biased towards the closed position. The spring arrangement 20 is described in more detail below.10 P005844-W001

[0062] In more detail, the plurality of pairs of plates 16 comprises of a row of evenly spaced second plates 18b (i.e. one for each pair), shown on their own in Fig. 5. The second plates 18b are fixedly connected to a base portion 22, to form a single unit. For example, the row of second plates 18b may be integrally formed with the base portion 22. The base portion 22 may comprise mounting points 24 (e.g. through-holes) for mounting the row of second plates 18b in the head portion 12 of the haircare device 10. The first plates 18a are then movably mounted in gaps between the second plates 18b. In particular, for each pair, the first plate 18a is movably mounted with the spring arrangement 20 being arranged to urge the first plate 18a towards the second plate 18b in that pair. The first plate 18a includes an engagement face 26 (see e.g. Fig. I la) which is configured to engage (contact) the second plate 18b in the closed position.

[0063] The head portion 12 of the haircare device 10 further includes a heater 32 (shown in Fig. 2) that is arranged to heat the row of second plates 18b. In particular, the heater 32 is arranged to heat the base portion 22, to thereby heat the second plates 18b. In the example shown, the heater 32 is a resistive heating plate which is in contact with a surface of the base portion 22 to transmit heat to the base portion 22. Other types of heater may also be used. For instance, in some examples, the heater may comprise a light source (e.g. infrared light source) arranged to irradiate the base portion 22 to heat the base portion 22 and the fixed plates 18b. A temperature sensor (e.g. thermocouple) may be provided for detecting a temperature of the heater 32. The temperature sensor may be used by a controller of the haircare device 10 for controlling the temperature of the heater 32, e.g. via a suitable feedback loop. The heater 32 may be configured to heat to any suitable temperature for drying and / or styling hair, and in some cases the temperature of the heater 32 may be adjustable. In some cases, the heater 32 may be configured to heat the plates to a temperature between 120 and 210 degrees Celsius. For example, the heater 32 may be configured to heat the plates to a temperature between 140 and 190 degrees Celsius. Such a temperature may provide effective drying and styling performance, whilst avoiding hair damage.

[0064] The heater 32 is enclosed within a housing 34 of the haircare device 10. The housing 34 may also enclose other components, such as control electronics for controlling operation of the heater 32. A power cable 36 is connected to an end of the handle portion 14, the power cable 36 being connectable to an external power source for powering the haircare device 10, and in particular for powering the heater 32. Additionally, or alternatively, the haircare11 P005844-W001 device 10 may be provided with an internal power source located in the housing 34, e.g. in the form of a rechargeable battery. A switch 37 is provided on the handle portion 14 for switching the heater 32 on or off.

[0065] Although a single unitary heater 32 is shown in the example of Fig. 2, other heater arrangements may be used. For example, there may be multiple heaters which are arranged to heat respective portions of the plurality of plates 16. For instance, for one or more of the pairs of plates 16, a heater may be disposed in the fixed second plate 18b. This may provide effective heating of the second plate 18b and transferring of heat to the first plate 18a when the plates are in contact with one another. In some examples (not shown), the plurality of pairs of plates may be arranged such that adjacent pairs of plates share a common fixed plate. In other words, the same fixed plate may act as the second plate for two adjacent pairs of plates. Then, a heater may be provided in the common fixed plate, i.e. so that the same heater can heat the two adjacent pairs of plates. Such an arrangement may contribute to reducing a number of heaters in the device, as heaters may be shared between adjacent pairs of plates.

[0066] The haircare device 10 further includes a plurality of guide members 38 which extend over the plurality of pairs of plates 16, to prevent (avoid) contact between the user’s scalp and the pairs of plates 16. The plurality of guide members 38 is made of a material having a lower thermal conductivity than the plurality of plates 16. In some cases, the plurality of guide members 38 may be made of a thermally insulating material, such as a glass filled plastic, polyphenylene sulphide or polyether ether ketone. The glass filled plastic may be, or comprise, glass filled nylon or glass filled polypropylene. The plurality of guide members 38 are aligned in a row and spaced so as to define a plurality of gaps 40. Each gap 40 is aligned with the channel of a respective one of the pairs of plates 16. Thus, for each pair of plates in the plurality of pairs 16, there is a corresponding pair of guide members 38 defining a gap 40 that is aligned with the channel between that pair of plates. The guide members 38 are thus arranged to guide hair into the channel between each pair of plates.

[0067] A plan view of a spring arrangement 20 for one of the pairs of plates 16 is shown in Fig. 6. The spring arrangement 20 is in the form of a plate of spring material, such as a thin plate of metal (e.g. steel), which is cut to define a first spring portion in the form of a cantilever 202 and a second spring portion in the form of a leaf spring 204. For example, the spring arrangement may be a steel leaf spring which is cut to define the cantilever 202. Fig. 7 shows a plan view of a back face 206 of the first plate 18a in one of the pairs. The spring12 P005844-W001 arrangement 20 is mounted on the back face 206 of the first plate 18a. In particular, the back face 206 may comprise a recess that is arranged to receive the spring arrangement 20. The back face 206 may further comprise a pair of tabs arranged to engage a corresponding pair of notches 208 in sides of the spring arrangement 20, to thereby retain the spring arrangement 20 in the recess. The back face 206 of the first plate 18a is on a side of the first plate 18a that is opposite the engagement face 26 of the first plate 18a which is arranged to engage hair in the channel between the first plate 18a and the second plate 18b. In other words, the back face 206 is on a side of the first plate 18a that faces away from the channel defined between the first plate 18a and the second plate 18b of that pair. Accordingly, for a given (e.g. first) pair of plates, the spring arrangement 20 is located between the first plate 18a of that pair, and the second (fixed) plate 18b of a directly adjacent pair. Thus, as shown in Fig. 4, there may be a gap 28 between the first plate 18a of the first pair, and the second plate 18b of the adjacent pair in which the biasing member 20 is located. In other words, the spring arrangements 20 are located in gaps 28 between adjacent ones of plurality of pairs of plates 16.

[0068] A back surface of the second plate 18b in each pair of plates 16 comprises an engagement portion arranged to engage the spring arrangement 20 of an adjacent pair of plates. In other words, the engagement portion is located in the gap 28. The engagement portion comprises a first engagement surface 210 arranged to engage the cantilever 202, and a second engagement surface 212 arranged to engage the leaf spring 204.

[0069] Figs. 8 to 11 illustrate an interaction between the spring arrangement 20 and the engagement portion on the second plate 18b of an adjacent pair of plates. Fig. 8 shows a side view of a first pair of plates 16a, comprising a first plate 18a and a second plate 18b as described above. The second plate 18bb of an adjacent pair of plates is also shown, with the first engagement surface 210 and the second engagement surface 212 on the back surface of the second plate 18bb being located in the gap 18 between the second plate 18bb of the adjacent pair and the first plate 18a of the first pair. Fig. 9a shows a cross-sectional view taken along the A-A plane indicated in Fig. 8, whilst Fig. 9b shows a cross-sectional view taken along the B-B plane indicated in Fig. 8. In the arrangement of Figs. 8, 9a, 9b, the first pair of plates 18a is in the closed position, i.e. the first plate 18a and the second plate 18b contact one another.13 P005844-W001

[0070] As shown in Fig. 9b, the cantilever 202 in the spring arrangement 20 is engaged with the first engagement surface 210, causing a free end of the cantilever 202 to be deflected away from the second plate 18bb. This results in the cantilever 202 exerting a force which presses the first plate 18a against the second plate 18b. However, as shown in Fig. 9a, there is a small gap (separation) between the second engagement surface 212 and the leaf spring 204, such that the leaf spring 204 is in a relaxed state (i.e. it is not deformed or deflected by the second engagement surface 212). Therefore, in the closed position illustrated in Figs. 8, 9a, 9b, only the cantilever 202 exerts a force urging the first plate 18a towards the second plate 18b (i.e. no force is exerted on the first plate 18a by the leaf spring 204).

[0071] Figs. 10, I la, 1 lb show views corresponding to Figs. 8, 9a, 9b, respectively, where the first plate 18a and the second plate 18b are spaced apart. Thus, Figs. 10, I la, 11b may correspond to an open position of the first pair of plates 16a, with the channel between the plates 18a, 18b being open to receive a portion of hair. For example, the first and second plates 18a, 18b may be moved apart by inserting a tress of hair between the plates. In the open position of Figs. 10, I la, 11b, the first plate 18a is moved closer to the second plate 18bb of the adjacent pair, i.e. the gap 28 is narrower. This results in an increased deflection of the end of the cantilever 202 by the first engagement surface 210. Additionally, in this position the second engagement surface 212 engages the leaf spring 204, e.g. in a central region of the leaf spring 204, causing leaf spring 204 to deform. In particular, as shown in Fig. I la, engagement of the second engagement surface 212 causes the leaf spring 204 to bow away from the second plate 18bb. Thus, in the open position, both the cantilever 202 and the spring leaf 204 both exert a force that urges the first plate 18a towards the second plate 18b.

[0072] Fig. 12 is a graph showing an example profile of a clamping force exerted on the first plate 18a and which urges the first plate 18a towards the second plate 18b. The clamping force results from the spring arrangement 20 exerting a force to urge the first plate 18a towards the second plate 18b, as discussed above. A horizontal axis of the graph indicates a displacement (distance) of the first plate 18a away from the second plate 18b. In other words, the horizontal axis indicates a width of the channel between the first plate 18a and the second plate 18b. As shown in the graph, in a first portion 120 of the movement of the first plate 18a away from the second plate 18b, the spring arrangement 20 provides a first, lower spring14 P005844-W001 rate (spring constant). In a second portion 122 of the movement of the first plate 18a away from the second plate 18b, the spring arrangement 20 provides a second, higher spring rate.

[0073] In the first portion 120 of the movement, only the cantilever 202 contributes to the clamping force, the spring leaf 204 being disengaged from the second engagement surface 212. Starting in the closed position and moving the first plate 18a progressively away from the second plate 18b, the clamping force increases due to the increased deflection of the cantilever 202, in accordance with a spring rate of the cantilever 202. At a predetermined displacement D of the first plate 18a, the second engagement surface 212 engages the spring leaf 204. The distance D corresponds to a separation between the leaf spring 204 and the second engagement surface 212 when the plates 18a, 18b are in the closed position. The first portion of the movement 120 corresponds to a movement of the first plate 18a between the closed position and the displacement D.

[0074] In a second portion 122 of the movement, where the first plate 18a is moved beyond the displacement D, both the cantilever 202 and the leaf spring 204 are engaged with the first and second engagement surfaces 210, 212, respectively. Thus, both the cantilever 202 and the leaf spring 204 contribute to the clamping force in the second portion 122 of the movement. This results in a higher combined spring rate for the clamping force in the second portion 122 of the movement than in the first portion 120 of the movement. Moreover, the cantilever 202 may have a lower spring rate compared to the leaf spring 204, further contributing to an increase in the spring rate when the second engagement surface 212 engages the spring leaf 204. The second portion 122 of the movement corresponds to a movement of the first plate 18a from the displacement D to a displacement M, which corresponds to a maximum separation of the plates 18a, 18b (i.e. maximum channel width).

[0075] As shown in Fig. 12 and in line with the discussion above for Figs. 8, 9a, 9b, the cantilever 202 provides a non-zero clamping force in the closed position, i.e. when the displacement is zero. In the first portion 122 of the movement, the cantilever 202 may be arranged to provide a relatively low clamping force. This may facilitate removing small portions of hair from between the plates 18a, 18b when the plates are close together, and help avoid snagging of hair strands between the plates. As an example, a maximum clamping force exerted by the cantilever 202 in the first portion 120 of the movement may be 2.5 N or less. In some cases, the maximum clamping force in the first portion 120 of the movement may be 0.25 N or less.15 P005844-W001

[0076] The distance D travelled by the first plate 18a in the first portion 120 of the movement may be selected to correspond to a relatively small amount of hair between the plates 18a, 18b. In line with the above, the distance D may be set by setting a distance between the leaf spring 204 and the second engagement surface 212 when the first and second plates 18a, 18b are in the closed position. For example, the distance D may be set to 0.6 mm or less. In some case, the distance D may be between 0.05 mm and 0.3 mm. Then, only a small number of strands of hair may fit in the channel between the first and second plates 18a, 18b in the first portion 120 of the movement. Thus, the lower clamping force and lower spring rate is only applied when a small number of hair strands are between the plates. When a larger volume of hair is received in the channel between the first and second plates 18a, 18b, the first plate 18a is displaced into the second portion 122 of the movement, resulting in a larger clamping force. The larger clamping force may result in a more efficient transfer of heat from the plates 18a, 18b to the hair in the channel, as well as facilitate tensioning the hair.

[0077] Figs. 13a and 13b illustrate an example of a plate arrangement that may be used in a haircare device according to the disclosure. For example, the arrangement of Figs. 13a, 13b may be used as part of the pairs of plates 16 in the haircare device 10. The plate arrangement of Figs. 13a and 13b is based on similar principles to the pairs of plates 16a, 16b described above, and features described above may be shared with the arrangement of Figs. 13a, 13b (and vice versa).

[0078] Figs. 13a, 13b show a side view of a first pair of plates 160a, including a first plate 180a and a second plate 180b. The first plate 180a is movable relative to the second plate 180b to vary a width of a channel between the first plate 180a and the second plate 180b, the second plate 180b being fixed to a base 22. A spring arrangement is configured to provide a clamping force to urge the first plate 180a towards the second plate 180b. The spring arrangement comprises a first spring element 190, which is coupled between a back face 192 of the first plate 180a and a second plate 180bb of an adjacent pair of plates. When the first plate 180a is moved away from the second plate 180b, the first spring element 190 is compressed, resulting in an opposing force from the spring element 190 that urges the first plate 180a towards the second plate 180b. The first spring element 190 may comprise any suitable type of spring, e.g. a coil spring, a conical spring, a leaf spring, or a piece of elastic material.16 P005844-W001

[0079] The spring arrangement further comprises a second spring element 192 which is arranged between the first plate 180a and the second plate 180b and which is arranged to oppose the force provided by the first spring element 190. For instance, as shown in Figs. 13a, 13b, the second spring element 192 may be provided on a face of the first plate 180a that faces towards the second plate 180a. Additionally or alternatively, the second spring element 192 may be provided on a face of the second plate 180b that faces towards the first plate 180a. The second spring element 192 is arranged to be compressed between the first plate 180a and the second plate 180b. The second spring element 192 may, for example, comprise one or more portions of elastomeric material, such as silicone or rubber.

[0080] Fig. 13a shows the first plate 180a in a first position, where the first plate 180a is close to the second plate 180b such that the second spring element 192 is in contact with the second plate 180b, e.g. the second spring element 192 may be compressed between the first and second plates 180a, 180b. This results in the second spring element 192 exerting a force on the first plate 180a which urges the first plate 180a away from the second plate 180b. Fig. 13b shows the first plate 180a in a second position, further from the second plate 180b (compared to the first position of Fig. 13a). In the second position of Fig. 13b, the second spring element 192 is not engaged with the second plate 180b, and so does not exert a force on the first plate 180a.

[0081] Fig. 14a shows a graph of a force exerted on the first plate 180a by each of the first spring element 190 and the second spring element 192, as a function of displacement of the first plate 180a away from the first position shown in Fig. 13a. Line 140 shows an example profile of the force provided by the first spring element 190. Thus, the first spring element 190 provides a force that increases linearly with displacement of the first plate 180a. The force provided by the first spring element 190 is shown as positive, to indicate that it urges the first plate 180a towards the second plate 180b. Curve 142 shows an example profile of the force provided by the second spring element 192. The force from the second spring element 192 is shown as negative, as it urges the first plate 180a away from the second plate 180b, and thus opposes the force from the first spring element 190. As shown by the curve 142, the force provided by the second spring element 192 initially decreases in magnitude in a substantially linear fashion when the first plate 180a is moved away from the second plate 180b. As the first plate 180a is moved further from the second plate 180b, the force from the second spring element decays to zero as the second spring element 192 is moved out of17 P005844-W001 contact with the second plate 180b. The second spring element 192 may have a larger spring rate than the first spring element 190, as illustrated by the larger slope of the curve 142 around zero displacement.Fig. 14b shows a graph of a total clamping force exerted on the first plate 180a by the spring arrangement, i.e. by the combination of the first and second spring elements 190, 192. Thus, the clamping force shown in Fig. 14b corresponds to a sum of line 140 and curve 142 from Fig. 14a. As shown in Fig. 14b, in a first portion 144 of the movement of the first plate 180a, the total clamping force is lowered due to the opposing force provided by the second spring element 192. At a distance D, the second spring element 192 becomes disengaged from the second plate 180b, such that only the first spring element 190 contributes to the clamping force. Thus, in a second portion of the movement 146 where the first plate 180a is moved beyond the displacement D, the clamping force follows the line 140. In this manner, a relatively low total clamping force is provided in a region near zero displacement due to the opposing force of the second spring element 192. Similarly to the discussion above, this may facilitate removing strands of hair and avoid snagging when there is a small displacement between the plates 180a, 180b.

[0082] The examples described above are illustrative of the present disclosure, and further examples are envisaged. It is to be understood that any feature described in relation to any one example may be used alone or in combination with other features of the example, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the disclosure, which is defined in the accompanying claims.

Claims

18 P005844-W001CLAIMS1. A haircare device comprising: one or more pairs of plates, each pair of plates comprising a respective first plate and second plate which are mutually opposed; a heater arranged to heat at least one of the first plate and the second plate in each pair of plates; and a spring arrangement; wherein each pair of plates is arranged to define a respective channel for receiving hair, each pair of plates being movable to vary a width of the respective channel; wherein, for each pair of plates, the spring arrangement is configured to provide a clamping force to resist a movement of the first plate and the second plate away from one another, the spring arrangement being configured to provide a first spring rate in a first portion of the movement where the first plate and the second plate are closer to one another, and to provide a second, different spring rate in a second portion of the movement the first plate and the second plate are further from one another, such that the clamping force is greater in the second portion of the movement than in the first portion of the movement.

2. The haircare device of claim 1, wherein each pair of plates is movable between a closed position where the first plate and the second plate contact one another, and an open position where the first plate and the second plate are spaced apart, and wherein the spring arrangement is configured to press the first plate against the second plate in the closed position.

3. The haircare device of claim 1 or 2, wherein the spring arrangement is configured to provide a maximum clamping force of 2.5 N or less in the first portion of the movement.

4. The haircare device of any preceding claim wherein a maximum separation between the first plate and the second plate in the first portion of the movement is 0.6 mm or less.19 P005844-W0015. The haircare device of any preceding claim, wherein each pair of plates is independently movable to vary the width of the respective channel, and wherein the spring arrangement comprises a respective spring arrangement for each pair of plates.

6. The haircare device of any preceding claim, wherein the first spring rate is lower than the second spring rate.

7. The haircare device of any preceding claim, wherein the spring arrangement comprises a spring having a variable spring rate.

8. The haircare device of one of claims 1 to 6, wherein the spring arrangement comprises a first spring portion configured to provide the first spring rate in the first portion of the movement, and a second spring portion configured to provide the second spring rate in the second portion of the movement.

9. The haircare device of claim 8, wherein: the first spring portion is configured to engage a first engagement surface to provide a first force urging the first plate and the second plate towards one another; the second spring portion is configured to engage a second engagement surface to provide a second force urging the first plate and the second plate towards one another; and the second spring portion is disengaged from the second engagement surface in the first portion of the movement.

10. The haircare device of claim 8 or 9, wherein the first spring portion comprises a cantilever.

11. The haircare device of one of claims 8 to 10, wherein the second spring portion comprises a leaf spring.

12. The haircare device of one of claims 8 to 11, wherein the first spring portion and the second spring portion are integrally formed as a single part.20 P005844-W00113. The haircare device of one of claims 8 to 12 wherein, for a first one of the one or more pairs of plates, the spring arrangement is connected between the first plate of the first pair of plates and the second plate of an adjacent one of the one or more pairs of plates.

14. The haircare device of one of claims 1 to 7, wherein the spring arrangement comprises a first spring element configured to provide a first force urging the first plate and the second plate towards one another, and a second spring element configured to provide a second force opposing the first force in only the first portion of the movement.

15. The haircare device of claim 14 wherein, for each pair of plates, the second spring portion is arranged to be compressed between the first plate and the second plate in the first portion of the movement.

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