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Title:
A HAIR STYLING APPLIANCE
Document Type and Number:
WIPO Patent Application WO/2019/073199
Kind Code:
A1
Abstract:
The present invention relates to a hair straightening apparatus having two arms pivotably coupled together and a heating plate on a facing side of at least one arm. A flexible protective rim substantially surrounds the periphery of a hair contacting surface of each heating plate.

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Inventors:
COURTNEY, Stephen (Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
SMITH, Arran (Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
NICOLAOU, Richard (Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
GROTRIAN, Frederick (Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
Application Number:
GB2018/052758
Publication Date:
April 18, 2019
Filing Date:
September 27, 2018
Export Citation:
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Assignee:
DYSON TECHNOLOGY LIMITED (Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
International Classes:
A45D1/04; A45D2/00
Domestic Patent References:
WO2017098199A12017-06-15
WO2011124137A12011-10-13
Attorney, Agent or Firm:
DYSON TECHNOLOGY LIMITED et al. (MACKISACK, AnnaIntellectual Property Department,Dyson Technology Limited, Tetbury Hill, Malmesbury Wiltshire SN16 0RP, SN16 0RP, GB)
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Claims:
CLAIMS

1. A hair styling apparatus comprising;

a first arm and a second arm coupled together at one end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart;

a heating plate located on the facing side of at least one of the first arm and the second arm, the heating plate having a hair contacting surface;

a protective rim substantially surrounding a periphery of the hair contacting surface of the heating plate and forming a contiguous surface with the hair contacting surface of the heating plate; and

wherein the protective rim is flexible.

2. A hair styling apparatus as claimed in claim 1, wherein the protective rim extends from the heating plate, aligned with the hair contacting surface, a distance in the range of 1mm - 5 mm. 3. A hair styling apparatus as claimed in claim 2, wherein the protective rim extends from the heating plate, aligned with the hair contacting surface, a distance in the range of 2mm - 3 mm.

4. A hair styling apparatus as claimed in any preceding claim, comprising a flexible skirt substantially surrounding the periphery of the protective rim, wherein the protective rim engages with the heating plate and the flexible skirt.

5. A hair styling apparatus as claimed in any preceding claim, wherein an outer surface of the protective rim is smooth.

6. A hair styling apparatus as claimed in any preceding claim, wherein the protective rim comprises at least one protrusion positioned to retain a gap between the facing side of the first arm and the facing side of the second arm, when the first arm and the second arm are in the closed position.

7. A hair styling apparatus as claimed in claim 6, wherein the at least one protrusion has a height approximately in the range of 0.1mm to 1.0mm.

8. A hair styling apparatus as claimed in any of claims 7, wherein the at least one protrusion has a height of approximately in the range of 0.15mm to 0.25mm.

9. A hair styling apparatus as claimed in any of claims 6 to 8, wherein the protective rim has a generally elongate rectangular form having two opposing long sides and two opposing short sides, wherein two protrusions are disposed on each long side of the protective rim.

10. A hair styling apparatus as claimed in claim 1, wherein the protective rim is comprised of PFA or PTFE. 11. A hair styling apparatus as claimed in claim 1, wherein the protective rim has a Young's Modulus in the range of 0.3GPa to 0.7GPa.

12. A hair styling apparatus as claimed in claim 1, wherein the protective rim has a Young's Modulus of approximately 0.5GPa.

13. A hair styling apparatus as claimed in any preceding claim, wherein the heating plate is flexible.

Description:
A HAIR STYLING APPLIANCE

The present invention relates to a hair styling appliance. Heated hair styling appliances are designed to use the action of heat and, optionally mechanical means to form hair into a desired shape or style.

In particular the present invention relates to a hair straightener, also known as a hair styling iron. A hair straightener conventionally includes two articulated arms which are pivotally attached to each other at one end and a heated plate positioned on inner facing surfaces of the arms at the other end. The heated plates generally have hair contacting surfaces which are designed to come into contact with hair to be styled during use of the hair straightener. Such a straightener can be seen in US7243661B.

Whilst a hair tress is gripped between closed arms of a hair straightener and subjected to high temperatures from the heated plates, there is a possibility of heat damage to the hair. Also, a tress of hair gripped between two flat and rigidly fixed heating plates is forced to splay widely across the plates, which is detrimental when styling hair into straight, even tresses. It is therefore desirable to provide an improved hair straightener. A first aspect of the present invention provides a hair styling apparatus comprising a first arm and a second arm coupled together at one end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a heating plate located on the facing side of at least one of the first arm and the second arm, a flexible edge substantially surrounding a periphery of the heating plate and wherein the flexible edge has a non-uniform resilience around the periphery of the heating plate. Preferably, the flexible edge comprises at least one reinforcing member which modifies the resilience of the flexible edge in proximity to the at least one reinforcing member. Further, the flexible edge may comprise at least one cut-out which modifies the resilience of the flexible edge in proximity to the at least one cut-out. Preferably, the flexible edge comprises a recess extending around the periphery of the heating plate. The flexible edge may comprise an outer wall, forming an external surface of the apparatus, and an inner wall, positioned within the apparatus, and the recess is located between the outer wall and the inner wall. In a preferred embodiment, the at least one reinforcing member supports part of the recess which maximizes the resilience of the flexible edge in proximity to the at least one reinforcing member. The reinforcing member may be a strut.

Preferably, at least one of the inner wall and the outer wall of the flexible edge comprises the at least one cut-out which minimizes the resilience of the flexible edge in proximity to the at least one cut-out.

Further, the heating plate may have an elongate form having an end portion at each end, and the flexible edge may have a maximum resilience at each end portion. It is desirable to urge a tress of hair to a middle portion of the heating plate as this provides an improved hair styling result. Specifically, retaining the tress of hair within the easily deformed middle portion of non-rigid heating plates minimises splaying of the tress and individual 'fly away' hair strands. In a preferred embodiment, the hair styling apparatus further comprises a support frame for supporting the heating plate, wherein the flexible edge engages with the heating plate and the supporting frame. The flexible edge may comprise two or more sections, each section substantially surrounding the periphery of the heating plate and each section comprised of a different material, wherein each different material has a predetermined resilience. Preferably, the relative proportion of each of the two or more sections within the flexible edge varies around the periphery of the heating plate which modifies the resilience of the flexible edge around the periphery of the heating plate, respectively. The flexible edge may comprise a flexible skirt for supporting the heated plate and a protective rim abutting the peripheral edges of heated plate. The flexible edge may comprise two sections, and a first section has a first keying feature and a second section has a second keying feature, wherein the first and second keying features cooperate. The flexible edge maintains flexible properties in hot and cold temperatures. The flexible edge is preferably comprised of one or more materials which have a smooth outer surface which does not snag or break strands of hair. It is preferred that the heating plate is flexible.

A second aspect of the present invention provides a hair styling apparatus comprising a first arm and a second arm coupled together at one end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a heating plate located on the facing side of at least one of the first arm and the second arm, the heating plate having a hair contacting surface, a protective rim substantially surrounding a periphery of the hair contacting surface of the heating plate and forming a contiguous surface with the hair contacting surface of the heating plate and wherein the protective rim is flexible.

Preferably, the protective rim extends from the heating plate, aligned with the hair contacting surface, a distance in the range of 1mm - 5mm, and more preferably, a distance in the range of 2mm - 3mm.

In a preferred embodiment, the hair styling apparatus further comprises a flexible skirt substantially surrounding the periphery of the protective rim, wherein the protective rim engages with the heating plate and the flexible skirt. An outer surface of the protective rim may be smooth, thereby avoiding any friction damage or breakage of a user's hair strands. The protective rim and the flexible skirt are comprised of materials having low thermal transfer properties, in order to hinder transfer of thermal energy away from the heated plate to parts of the appliance that the user may hold.

In a preferred embodiment, the protective rim comprises at least one protrusion positioned to retain a gap between the facing side of the first arm and the facing side of the second arm, when the first arm and the second arm are in the closed position. Preferably, the at least one protrusion has a height approximately in the range of 0.1mm to 1.0mm, and more preferably, a height of approximately in the range of 0.15mm to 0.25mm.

The protective rim may have a generally elongate rectangular form having two opposing long sides and two opposing short sides, wherein two protrusions are disposed on each long side of the protective rim. The protective rim may be comprised of PFA or PTFE. Preferably, the protective rim has a Young's Modulus in the range of 0.3GPa to 0.7Gpa, and more preferably, a Young's Modulus of approximately 0.5GPa. The protective rim should be adequately resilient such that the heated plate is always retained within the protective rim.

In a preferred embodiment, the heated plate is flexible. The heated plate flexes or deforms from the flat arrangement only where a hair tress is located between the heated plates and therefore, the attached flexible skirt and attached protective rim also deform at that specific location. In use, this is advantageous because a user's tress of hair is retained within the deformed section of the heated plate, thereby minimising the tress spreading out across the plate. It is desirable to retain a tress of hair in the middle portion of the heating plate as this provides an improved hair styling result.

A third aspect of the present invention provides a hair styling apparatus comprising a first arm and a second arm coupled together at one end thereof to allow the first arm and the second arm to be moveable between a closed position, in which a facing side of the first arm and a facing side of the second arm are adjacent, and an open position, in which the facing side of the first arm and the facing side of the second arm are spaced apart, a heating plate located on the facing side of at least one of the first arm and the second arm, and an aluminium nitride ceramic heating element in thermal connection with the heating plate. The aluminium nitride ceramic heating element may be a single-sided heating element or a double-sided heating element. The aluminium nitride ceramic heating element may be a thick film heating element or a thin film heating element.

In a preferred embodiment, the heating plate is flexible. Advantageously, use of an aluminium nitride ceramic heating element enables even transfer of thermal energy to a heating plate which is not constant in shape. Consequently, an even heat can be transferred to the hair tress during the hair styling process, which is critical for forming the tress as the user expects. In a further preferred embodiment, the aluminium nitride ceramic heating element is flexible. In a yet further preferred embodiment, the aluminium nitride ceramic heating element and the heating plate are integrated to comprise a single flexing entity.

Preferably, the hair styling apparatus comprises a thermal interface material disposed between the aluminium nitride ceramic heating element and the heating plate. The hair styling apparatus may further comprise an insulation block disposed on the aluminium nitride ceramic heating element, and may alternatively have the thermal interface material disposed between said insulation block and the aluminium nitride ceramic heating element.

An embodiment comprising a combination of a relatively deep flexible edge and relatively large resilient supports provides additional movement of the heating assembly in an orientation generally perpendicular to the length axis of the apparatus. In use, such perpendicular movement can occur consequent to a force applied to the hair contacting surface of the heated plate. This perpendicular movement is distinct from the deformation of the hair contacting surface caused by a force applied to the hair contacting surface of a flexible heated plate (generally caused by a hair tress between the heated plates when the arms are in the closed position). The perpendicular movement of the heating assembly may occur in addition to, or separately from, any deformation of the hair contacting surface. Perpendicular movement of the heating assembly may be in the range of 0.5mm to 20mm, and preferably in the range of 3mm to 15mm. The perpendicular movement of the heating assembly provides a visual and tactile indication to the user that the heated plate is supported within a flexible framework. The relatively deep flexible edge may allow some lateral and transverse movement of the heating assembly, in addition to the perpendicular movement described above.

The terms "heating plate" or "heated plate" both refer to a flexible or non-flexible hair contacting plate, which may have an increased temperature when the hair straightening apparatus is in use. When the hair straightening apparatus is not in use, the plate will generally be at the ambient temperature.

In order that the present invention may be more readily understood, an embodiment of the invention will now be described, by way of example, and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a hair straightener according to the present invention;

Figure 2 is a perspective view of the hair straightener shown in Figure 1 with the arms in an open position;

Figure 3 is a sectional view through a hair contacting section of one arm of the hair straightener;

Figure 4 is a cross-sectional view through a heating assembly of the hair contacting section of Figure 1; Figure 5 is an exploded view of the heating assembly shown in Figure 4;

Figure 6 is a schematic sectional view through an A1N thick film heater; Figure 7 is a perspective view of an embodiment of a flexible skirt;

Figure 8a illustrates a series of resilient members along an inner cavity of the flexible skirt; Figure 8b, 8c and 8d schematically represent alternative embodiments of resilient members;

Figure 9a, 9b and 9c schematically represent various embodiments of cut-outs in the flexible skirt;

Figure 10 is a perspective view of an alternative embodiment of a protective rim.

A hair straightener 10 shown in Figures 1 and 2 comprises a first arm 12 and a second arm 14 which are joined together at one end by a hinge 16. A power supply cable 18 is located at the hinge end of the hair straightener 10. The hair straightener 10 comprises a handle section 20 towards the hinge end of the arms and a hair contacting section 22 towards the distal end of the arms. The hair contacting section 22 comprises a heated plate 24 arranged on at least one of the facing surfaces of the hair contacting section 22. An actuation button 26 is positioned on the handle section 20 and the actuation button 26 switches on the power to the heated plate 24 and may also function to release the arms from a closed position.

With reference to Figure 3, a monocoque 28 provides a protective external casing around a heating assembly 30, whilst the heated plate 24 and several supporting components remain exposed. The heated plate 24 is formed as a single piece and has an exposed, smooth, hair contacting surface 32. An opposing side 33 to the hair contacting surface 32 has a plurality of grooves 34 which run across the width of the heated plate 24 and enable to the heated plate 24 to flex.

The heated plate 24 is generally a shallow cuboid in form and thus the hair contacting surface 32 is generally rectangular in shape. The heated plate 24 may be formed from any suitable material which can transfer heat from the heated plate 24 to the hair tress to be straightened. Examples of suitable materials are metals and alloys of metals such as aluminium, copper, steel, titanium, brass and beryllium copper. Preferably, the heated plate 24 is formed from brass CZ114 which, when heated, advantageously maintains a high temperature for a longer duration than other copper based alloys. The hair contacting surface 32 of the heated plate 24 may have a series of parallel linear surface indentations running across the width of the heated plate which provide benefit in aligning the hair tress across the heated plate 24. With reference to Figures 4 and 5, the heated plate 24 extends across the width of the heating assembly 30. A protective rim 36 extends around the edge of the heated plate, thereby providing a contiguous smooth surface at the sides of the hair contacting face. The heated plate 24 further comprises two walls 38, 40 which each extend from the opposing side 33 of the heated plate in proximity to the long edges of the heated plate, and continue along the length of the heated plate 24. A channel 42, 44 formed in each wall 38, 40 respectively, receives a correspondingly shaped ridge 46 of the protective rim 36. The distal end of each wall 38 forms a runner 48 at a right angle to the respective wall 38 and each runner 48 extends parallel to the hair contacting surface of the heated plate 24. The runners engage with a first ledge 50 of a frame 52. The frame 52 has a C-shaped profile and is a rigid metal structure of die-cast aluminium which is relatively lightweight. Advantageously, the aluminium frame 52 maintains its form without any deformation in excessively high temperatures.

A ceramic heater 54 has a generally shallow cuboid form and therefore has a first face 56 and a second face 58. The first face 56 of the ceramic heater 54 is positioned towards the opposing side of the heated plate 24. The ceramic heater 54 is an aluminium nitride (A1N) ceramic block 60 with conductive elements 62 running along the length of the heater. The conductive elements 62 are preferably a conductive ink screenprinted onto a surface of the ceramic block or may alternatively be embedded through the middle of the ceramic block 60. Where the conductive elements 62 are positioned on the surface of the ceramic block 60, then a protective glass layer 64 covers the conductive elements and surface of the ceramic block, as shown in Figure 6. In use, such an A1N ceramic heater may reach a styling temperature of 120°C in 15 seconds. Advantageously, the aluminium nitride ceramic heater 54 enables a uniform spread of heat across the surface of the heater, even during deformation of the heated plate.

Between the first face 56 of the ceramic heater and the heated plate 24 is a thermal interface referred to as a gap pad 66. The gap pad 66 is a high conductivity component to support thermal transfer between the ceramic heater 54 and the heated plate 24. The gap pad 66 comprises a flexible, graphite-doped silicone sheet having width and length dimensions approximately similar to the ceramic heater 54, and a thickness in the range of 0.25mm to 1mm, and ideally 0.5mm.

The second face 58 of the ceramic heater 54 is in contact with a fast reacting bi-metallic thermal fuse block 68. Thermal insulation 70 surrounds both the thermal fuse block 68 and the second face 58 of the ceramic heater and the insulation 70 extends along the length of the ceramic heater 54. The insulation 70 may be retained adjacent the second face 58 of the ceramic heater 54 by means of the frame 52. The insulation 70 serves to reduce the temperature of the outer parts of the heating assembly 30 and consequently the monocoque 28 surrounding the heating assembly 30 does not become uncomfortably hot for the user. A thermal fuse bracket 72 is positioned around the thermal fuse block 68, and the insulation 70 is directly adjacent to the thermal fuse block 68. The thermal fuse bracket 72 holds the thermal fuse block 68 in position when there is movement of components within the heating assembly 30. A spring element 74 is located in contact with the rigid insulation block 70 and may be secured within the insulation 70 in one or more locations. The spring element 74 functions to provide a constant force urging the ceramic heater 54 and gap pad 66 into contact with the heated plate 24 and also urging the heated plate 24 towards the hair tress.

A flexible skirt 76 is located around the periphery of the heated plate 24. The protective rim 36 is positioned to form a contiguous surface between the hair contacting surface 32 of the heated plate 24 and an outer surface of the flexible skirt 76, thereby avoiding contact between the user and the hard metal edge of the heated plate 24. The flexible skirt 76 functions to receive the flexing movement of the heated plate 24. Whilst the protective rim 36 also flexes in response to deformation or movement of the heated plate 24, it is relatively less flexible than the flexible skirt 76 and therefore limits the reactive force of the heated plate 24.

The flexible skirt 76 is formed of silicone and has a Young's modulus between O.OlGPa and O. lGPa, and the protective rim 36 is formed of PFA or PTFE and has a Young's modulus of approximately 0.5GPa. The flexible skirt 76 further comprises a male keying feature 78 which engages with a female keying feature 80 in the protective rim 36, in order to avoid the two parts becoming separated when they are deformed.

A void is located between the opposing side 33 of the heated plate 24 and the first ledge and adjacent the wall extending from the opposing side of the heated plate. The first ledge 50 and the heated plate 24 may move into the void consequent to movement of, or deformation in, the heated plate 24 or the flexible skirt 76. Further, the runner 48 and the first ledge 50 engage in such a way that allows the heated plate 24 to be slid into position on the frame 52 during assembly.

An inner portion of the flexible skirt 76, which is shown in Figure 7, comprises moulded slots 82 for mechanical engagement with a second ledge 84 of the frame 52, and moulded slots 86 for mechanical engagement with the runner 48 of the heated plate 24.

An outer section of the flexible skirt 76 comprises a recess 88 which forms a closed cavity with the wall 38 of the heated plate. The cavity extends along the two elongate sides of the heating assembly 30, and may also extend along one or both of the short sides of the heating assembly 30.

With reference to the embodiment of the flexible skirt 76 illustrated in Figure 7, it is noted that the slot 82 in the inner section of the flexible skirt 76 to receive the second ledge 84 of the frame 52 is not continuous but a series of slots 82. Such an arrangement provides better stability for the entire component and greater resilience to compression, than a continuous recess. Similarly, the second series of slots 86 shown in the flexible skirt 76 receive the runner 48 of the heated plate 24.

The recess 88 formed within the outer section of the flexible skirt 76 can be seen in Figure 8a. A series of moulded diagonal struts 90 span the recess 88. A middle section 99 of the long side of the flexible skirt 76 is devoid of struts 90. Therefore, the middle section 99 of the flexible skirt has a reduced resistance to compressive forces which occur consequent to pressure on, or deformation of, the heated plate 24. The series of struts 90 has the same form in both long sides of the flexible skirt. Advantageously, diagonal struts will not buckle or deform, but flex towards an orientation parallel to the length of the recess 88. In order to achieve a reduced resistance to compressive forces in the middle section 99 of the length of the flexible skirt 76, several alternative embodiments are possible. Figures 8b to 8d represent the spacing of struts spanning the recess at one side of the middle section 99 of the length of the flexible skirt 76. Whilst the struts in Figures 8b to 8d are represented as perpendicular struts, the struts may have another orientation, such as diagonal. Struts may be regularly spaced as shown in Figure 8b. Struts may have a varying spacing, wherein the space between the struts incrementally decreases towards the short ends of the flexible skirt, as shown in Figure 8c. Further, the struts may have a varying width, wherein the width, and hence the resistance, of the struts incrementally increases towards the short ends of the flexible skirt, as shown in Figure 8d. Further still, the material of the struts may be varied in order to achieve the stated effect; the struts towards the short ends of the flexible skirt can be formed of a material of a relatively greater shore factor than the struts towards the middle section of the flexible skirt. For example, a dual material such as twin-shot silicone can be used.

A reduced resistance to compressive forces in the middle section 99 of the length of the flexible skirt 76 may also be achieved by a series of cut-outs in the flexible skirt 76. Each cut-out weakens the structure, thereby providing a reduced resistance to compressive forces incident on the flexible skirt in proximity to the cut-out. The cutouts may have various shapes, although the spacing between each cut-out and the size of the each cut-out is instrumental in controlling the resistance to compressive forces of the flexible skirt structure. Examples of such cut-outs; triangular, circular and rectangular are illustrated schematically in Figures 9a to 9c, respectively. Where several cuts-outs extend along the flexible skirt in a series, the cut-outs may be of several different shapes. The moulded cut-outs in the flexible skirt are preferably located on the inner side of the flexible skirt, thereby avoiding ingress of external moisture and dirt.

The extent of flexing of the heated plate can also be controlled by predetermined variations in cross-section of the flexible skirt. In such an embodiment, an external view of the appliance would generally show a flexible skirt of non-uniform depth. The extent of flexing of the heated plate can also be controlled by the protective rim having predetermined variations in cross-section. In such an embodiment, an external view of the appliance would generally show a protective rim of non-uniform depth. Furthermore, through predetermined variations in the cross-sections of both the flexible skirt 76 and protective rim 36, resilience to compressive forces along the length of the heated plate 24 can be accurately controlled. Furthermore, the protective rim 36 is comprised of a material having a relatively low surface friction and the flexible skirt 76 is comprised of a material having a relatively high surface friction. In use, a tress of hair is positioned transversely across a heated plate 24. Where the tress contacts the protective rim 36, the tress may slide over the protective rim. Where the tress contacts the flexible skirt 76, the tress may have a reduced capacity for movement. Therefore, through variation in the extent of protrusion of the protective rim and flexible skirt at the external surfaces of the hair contacting section of the appliance, the tress can be "guided" to an optimal position on the heated plate. For example, greater contact between the tress and the protective rim at the distal end of the arms allows the tress to slide towards the middle of the heated plate. However, contact between the tress and the flexible skirt should be preferably avoided during the hair straightening process, as increased tension and drag on the hair tress is undesirable and uncomfortable for the user. The protective rim 36 may have separation protrusions 92 as illustrated in Figure 10 in order to maintain separation at all times between the two hair contacting surfaces. The separation protrusions 92 may be smooth bumps of approximately 0.1mm to 1.0mm in height, or more particularly 0.15mm to 0.2mm. Such separation protrusions avoid individual strands of hair being sandwiched between the two hair contacting surfaces (of which, one or both are heated) and excessive pulling forces being exerted on such individual strands of hair.

A monocoque 28 covers the heating assembly 30 and extends between the flexible skirt on each side of the heated plate. The monocoque is affixed to the flexible skirt by a mechanical join, such as a clamp. The monocoque is formed from polycarbonate, such as PA 30 GF, PBT 30 GF or PET, and comprises an inner surface and an outer surface.

A plurality of resilient supports 94 are located between the heating assembly 30 and the inner surface of the monocoque, as illustrated in Figure 3. These resilient supports 94 are composed of a resilient material such as silicone rubber and allow the heating assembly 30 to move relative to the monocoque if subjected to pressure. Therefore, in addition to the heated plate being able to flex under pressure, the heated plate may also move towards the inner surface of the monocoque. In a preferred embodiment, each resilient support 94 has a domed form 95 with an elongate peg 97 form on the base and the peg 97 has an encircling lip. The peg 97 extends through an aperture in the heating assembly 30 and the lip functions to secure it in position.

The outer surface of each edge of the monocoque may protrude beyond the profile of the flexible skirt. Further, the profile of the flexible skirt may be angled from the outer surface of the monocoque inwards towards the heated plate, in order to avoid contact between the user's hair tress and the flexible skirt. Such contact with the surface of the flexible skirt would increase friction incident on the hair tress during the hair straightening action which may be undesirable at predetermined sections of the appliance. The form of the monocoque 28 at the distal end of each arm has a diagonal profile 96 wherein the monocoque extends beyond the end of the heated plate assembly and then turns inwards on a diagonal path towards the end of the heated plate. This is illustrated in Figures 1, 2 and 3. The end profile 98 of the flexible skirt 76 continues the same diagonal profile as the monocoque, at the distal end of each arm. The end profile 100 of the protective rim 36 continues the same diagonal profile 96 as the monocoque 28, at the distal end of each arm. The second arm 14 is symmetrical to the first arm 12 and, therefore, a V-shaped end profile is formed at the distal end of the hair straightener 10. This shape functions to urge the user's hair tress towards the heated plates. Also, the diagonally protruding distal end of the monocoque 28 of each arm may not contain any components and, therefore, functions to insulate the outer monocoque surface from the heating assembly 30.

In use, when a force is applied to the hair contacting surface, for example when a tress of hair is sandwiched between the first arm 12 and the second arm 14, and the arms are pressed together, the heated plate flexes. In use, the hair contacting surface 32 of the heated plate 24 may have a temperature between 50°C and 250°C, and more preferably between 150°C and 210°C.

On the handle section 20, the monocoque 24 completely surrounds each arm and facing monocoque sections of the first arm 12 and the second arm 14 are generally planar. The internal arrangement of the first arm and second arm may be asymmetric.

It will be apparent to the skilled person that various alternatives are possible within the scope of the present invention. For example, the ceramic heater 54 may be any suitable heater, such as an aluminium oxide ceramic heater. The ceramic heater 54 may comprise an embedded trackway or thick-film trackways. The heater may alternatively be a flexible, low power heater, such as a polyimide (Kapton) insulated etched foil heater or a cartridge heater using Nichrome wire wound around a ceramic core. Yet further still, the heater 54 may be an ohmic heater or alternatively utilise infra-red or microwave radiation.

In an alternative embodiment, the thermal interface element, referred to as the gap pad 66, is located between the ceramic heater 54 and the insulation block 68, which may improve heat distribution. Further, the gap pad 66 may be comprised of a flexible rubber sheet or silicone paste or non-silicone paste. Conductive fillers in the gap pad 66 material may be carbon black, graphite flakes, silver, nickel, copper or aluminium.

In further alternative embodiments, the heated plate 24 and the heater 54 may be a single amalgamated unit; either having the heater 54 embedded in the heated plate 24, or having the heated plate 24 comprised of heater material. Further, the protective rim 36 and the flexible skirt 76 may be a single amalgamated unit; either having the flexible skirt overmoulded onto the protective rim 36, or having a single flexible edge component performing the functions of both the protective rim and the flexible skirt through its structure and surface finishes. Further, the monocoque 28 may be affixed to the flexible skirt by an overmoulding process, either alone or in addition to a mechanical join.

The insulation 70 may be comprised of a generally hollow rigid plastic moulding having relatively thin, rigid internal walls defining insulating air gaps. Alternatively, the insulation block 70 may be comprised of a mouldable insulating material.

The resilient element, shown as reference numeral 94 in Figure 3, may alternatively be any suitable resilient element, such as one or more coil spring(s), or a linear spring, or an L-shaped end spring at each end of the insulation block. In an embodiment having maximum movement of the heated plate relative to the monocoque, in addition to deformation of a flexible heated plate, the resilient element(s) may be larger in size than those illustrated in Figure 3. The protective rim 36 may be comprised of any suitable smooth, resilient, insulating material, and the monocoque 28 may be formed from any suitable plastics material.

The heated plate 24, and therefore the hair contacting surface 32, may have a form which is non-rectangular in shape, such as a square, an oval or an irregular form. The deformation of the heated plate 24 may be supported by any arrangement around the edge of the heated plate which has a non-uniform spring force. The skilled person would be aware that such an arrangement could also extend to a non-uniform spring force along an edge of the monocoque 28.

In a yet further alternative, the heated plate 24 may be a regular, non-flexing heated plate.

Separation protrusions 92 on the appliance may be located on the hair contacting surface 32 of the heated plate 24 and/or on the protective rim 36. The separation protrusions may take the form of rounded bumps or a raised ridge extending transversely across some or all of the heated plate and protective rim. The separation protrusions 92 may be situated on either of the first arm 12 or second arm 14, or on both of the first and second arms.

Alternatively, the insulation block 68 may be retained adjacent the second side of the heater 54 by means of a plate carrier. A plate carrier may have a trough form and surrounds at least the insulation and a linear spring. Such a plate carrier may be comprised of LCP to provide stability at high temperatures.

The invention is not limited to the detailed description given above. Variations will be apparent to the person skilled in the art.