Heater assembly

Abstract

A heater assembly for a hair care device is described. The heater assembly includes a contact member defining a hair contacting surface, where the contact member includes a heat dissipating layer. The heater assembly also includes one or more heating elements for heating the contact member. The lateral thermal resistance of the heat dissipation layer is not greater than 22 Kelvin / W.

Description

Technical Field

[0001] The present invention relates to a heater assembly for a hair care appliance and a hair care appliance comprising the heater assembly. Background Art

[0002] The hair care appliance can utilize a pair of heated clamps to style the user's hair. When in use, the hair strand is clamped between the heated clamps and the hair care appliance is pulled along the length of the hair strand. The process can then be repeated to style the entire head of hair.

[0003] In known arrangements, the thickness of each clamping plate may have a thickness of approximately 2 to 3 mm and may be made of, for example, stainless steel, aluminum, copper or brass. Clamping plates of this thickness are relatively stiff and do not have the flexibility to achieve a corralling effect for gathering and shaping the hair. In addition, thicker clamping plates have a slower thermal response than thinner clamping plates, which means that the temperature of the thicker clamping plates cannot generally be adjusted as quickly as the thinner clamping plates. Therefore, the use of thicker clamping plates may result in reduced controllability and flexibility of the hair care appliance.

[0004] However, reducing the thickness of the plates to much less than the above 2-3 mm values ​​can be problematic as it can result in uneven temperature distribution over the surface of the plates when used heated. This can result in hot spots which can burn and damage the hair clamped between the plates and can even cause the plates themselves to suffer permanent deformation in some circumstances.

[0005] An object of the present invention is to provide an improved heater assembly for a hair care appliance. Summary of the invention

[0006] In a first aspect, the present invention provides a heater assembly for a hair care appliance. The heater assembly includes a contact member defining a hair contact surface, wherein the contact member includes a heat sink layer. The heater assembly includes one or more heating elements for heating the contact member. The heat sink layer has a lateral thermal resistance of no greater than 22 Kelvin / Watt.

[0007] The use of a heat sink layer having a lateral thermal resistance of no greater than 22 Kelvin / Watt in a hair care appliance advantageously improves heat distribution on the hair contact surface, thereby reducing the likelihood of hot spots forming on the hair contact surface. In this way, the risk of damage to the hair due to excessive heating is reduced. In addition, the safety of the hair care appliance including the heater assembly is improved.

[0008] The heat dissipation layer may have a thickness of no more than 500 μm. The heat dissipation layer may have a thickness of no more than 200 μm. In order to provide the heat dissipation layer and the heater assembly with better flexibility, it is preferred to use a thinner heat dissipation layer. Better flexibility facilitates the realization of gathering (wherein hair is gathered and styled) using a hair care appliance including a heater assembly. Therefore, the heating assembly advantageously provides improved styling capabilities of the hair care appliance.

[0009] The heat dissipation layer can be formed of stainless steel and copper trimetallic material, copper or pyrolytic graphite. These materials advantageously have material parameters, namely thermal conductivity, such that a lateral thermal resistance of no more than 22 Kelvin / Watt can be achieved using a relatively small thickness of heat for a given arrangement. This allows the use of relatively thin and flexible components to achieve the desired heat dissipation effect.

[0010] The contact member may include a stainless steel plate. The heat dissipation layer may be disposed on a surface of the stainless steel plate. In some examples, the heat dissipation layer may be disposed on an outer surface of the stainless steel plate to define a hair contact surface. In other examples, the heat dissipation layer may be disposed on an inner surface of the stainless steel plate. In addition, the heat dissipation layer may be disposed away from the stainless steel plate at any suitable location in the heater assembly.

[0011] At least one of the heating elements may comprise a thin film heater. The heating elements may together cover no less than 50% of the area of ​​the hair contacting surface of the contact member. The heating elements may together extend across no less than 95% of the length of the hair contacting surface of the contact member. Such coverage of the hair contacting surface by the heating elements is advantageous as it helps to provide a more even distribution of heat over the hair contacting surface.

[0012] The heater assembly may have a value less than 0.004 JK -1 .mm -2 A relatively low heat capacity (i.e., low thermal mass) can be beneficial because it allows the heater assembly to respond more quickly to heating needs. For example, the heater assembly can heat up to operating temperature more quickly, and / or respond more quickly to temperature changes during use, such as when hair is contacted with and then subsequently removed from the heater assembly.

[0013] The heater assembly may include a plurality of heating elements to define a multi-element heater assembly.

[0014] The heating elements may together draw no more than 500W of power from the power source for heating the contact member. In other words, the total maximum power supplied to the heating elements may be 500W, so that the heating elements together have a power cap of 500W. In this way, the maximum thermal energy supplied to the heater assembly is limited to prevent the formation of hot spots anywhere within or on the heater assembly. Limiting the maximum power supplied to the heating elements limits the thermal energy provided by the heating elements, and therefore limits the thermal energy reaching the contact member of the heater assembly. This ensures that the contact member can effectively dissipate the heat received from the heating element, thereby avoiding the occurrence of hot spots on or in the contact member.

[0015] A second aspect of the invention provides a hair care appliance comprising a heater assembly according to any of the preceding paragraphs. The hair care appliance may include a controller configured to control the power supplied to each heating element. In particular, the controller may be configured to independently control the power supplied to each of the heating elements. This enables the temperature of each heating element to be independently controlled and provides a more controllable and flexible styling process.

[0016] The heater assembly may include at least one electrically insulating layer between the heating element and the contact member. In this way, the contact member is electrically isolated from the heating element or elements, improving the safety of the device.

[0017] The heater assembly may include one or more sensors for sensing the temperature at one or more locations of the contact member, in particular the temperature at one or more locations of the hair contact surface. The controller may be configured to control the power supplied to each heating element based on the temperature indicated by the one or more sensors. In this way, the amount of heat generated by each heating element may be independently controlled based on the temperature of the hair contact surface area associated with the heating element. This allows for better control of the temperature on the hair contact surface of the heater assembly, thereby improving the styling capabilities of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a side view of the arm of the hair care appliance in an open position;

[0019] Figure 2 yes Figure 1 a perspective view of the hair care appliance with the arms in a closed position;

[0020] Figure 3 yes Figure 1 A partially exploded view of a hair care appliance;

[0021] Figure 4 yes Figure 1 an exploded view of a portion of a heating section of a hair care appliance;

[0022] Figure 5 yes Figure 1 an exploded view of a heater assembly of a hair care appliance;

[0023] Figure 6 yes Figure 5 Cross-sectional view of the heater assembly.

[0024] Figure 7 yes Figure 5 A perspective view of a heat dissipation layer of a heater assembly;

[0025] Figure 8 is a plan view of an alternative example of a sensor and heating element layer of a heater assembly; and

[0026] Fig. 9 is a plan view of another alternative example of a sensor and heating element layer of a heater assembly. DETAILED DESCRIPTION

[0027] Figure 1 and Figure 2 The hair care device 10 includes a first arm 12 and a second arm 14, one end of which is pivotally connected by a hinge 16. The arms 12 and 14 can be pivotally connected about the hinge 16 in an open position (such as Figure 1 as shown) and the closed position (as Figure 2 The hair care appliance 10 may take the general form of a hair straightener.

[0028] Each arm 12, 14 includes a heating section 22, 24 located at one end of each arm 12, 14 away from the hinge 16, and a handle section 26, 28 located at the opposite end of each arm 12, 14 where the hinge 16 is located. In use, the user grasps the handle sections 26, 28 and inserts a section or strand of hair between the two arms 12, 14. The user applies pressure to the handle sections 26, 28 to close the arms 12, 14 and clamp the hair between the heating sections 22, 24, and pulls the hair care appliance 10 along the length of the hair to be styled. The arms 12, 14 are biased toward the open position so that when the user releases pressure on the handle sections 26, 28, the arms 12, 14 return to the open position and release the strand of hair.

[0029] Reference now Figure 3 and Figure 4The heating section 22, 24 of each arm 12, 14 includes a housing 30, a heater assembly housing 32, a heater assembly 34, and a support member 38. The housing 30 defines a slot 31, and the heater assembly housing 32 is located in the slot 31. The heater assembly housing 32 includes a recess 33, and the support member 38 and the heater assembly 34 are located in the recess 33. The support member 38 is located between the heater assembly housing 32 and the heater assembly 34, and supports the heater assembly 34 in the heater assembly housing 32. The heater assembly 34 is located on the top of the support member 38. That is, the heater assembly 34 is located on the side of the support member 38 away from the heater assembly housing 32.

[0030] Now we will especially refer to Figure 5 and Figure 6 The heater assembly 34 will now be described.

[0031] The heater assembly 34 comprises a plurality of layers of components arranged in a stack. Specifically, the heater assembly 34 comprises a sensor and heating element layer 40, an electrical insulating layer 41 and a contact member 42 which defines a hair contacting surface 37 of the hair care appliance 10 for contacting and styling hair during use.

[0032] The heater assembly 34 preferably has a thermal conductivity of no more than 0.004 JK. -1 .mm -2 The relatively low heat capacity per unit area of ​​the hair contact surface 37. The lower the heat capacity per unit area, the better, because as this value increases, the thermal responsiveness of the heater assembly 34 decreases. Therefore, the heat of the heater assembly 34 with a lower heat capacity per unit area allows the contact member 42 and the hair contact surface 37 to heat and cool more quickly, which can better control the temperature of the hair contact surface 37 to improve the safety of the hair styling and hair care appliance 10.

[0033] exist Figure 5 and Figure 6 In the orientation of the heater assembly 34 shown, the sensor and heating element layer 40 is located below the electrical insulation layer 41. In this manner, the sensor and heating element layer 40 defines an inner layer of the heater assembly 34 away from the hair contacting surface 37. In this example, the electrical insulation layer 41 is located above a dielectric cover 52, which is made of a flexible silicone backing 54 (such as Figure 6 ) is overmolded, thereby allowing the contact member 42 to be enclosed with the hair contact surface 37.

[0034] In this example, the sensor and heating element layer 40 has a thickness of 0.05 mm, but in other examples, the thickness of the sensor and heating element layer 40 may vary. However, in general, it is preferred to use a thinner sensor and heating element layer 40 for increased flexibility.

[0035] The sensor and heating element layer 40 includes a substrate 49, a plurality of heating elements 50 and a sensor 48. The substrate 49 supports and positions the sensor 48 and the heating element 50 within the heater assembly 34, and also provides an electrical insulation portion that insulates the heating element 50 from each other and from the sensor 48. In this example, the substrate 49 has the same shape and area as the electrical insulation layer 41 and the contact member 42, and includes a layer of glass-based dielectric material that supports the sensor 48 and the heating element 50. However, other materials such as prepreg (partially cured fiber resin composite sheet material that can be used for electrical insulation and bonding) or polyimide can also be used. In addition, in other examples, the substrate 49 may include more than one layer or sheet, and the sensor 48 and the heating element 50 are located on the layer or sheet or between the layers or sheets. In addition, the sensor 48 and the heating element 50 can be arranged on different layers from each other so as to define different sensor layers and different heating element layers. In this case, the sensor layer and the heating element layer can be separated by a layer of insulation. It should be noted that in other examples, additional sensors 48 may be included, such that the sensor and heating element layer 40 may generally include one or more sensors 48. In some cases, the sensor and heating element layer 40 may include an equal number of sensors 48 and heating elements 50, such that each heating element 50 has an associated sensor 48. In examples where the sensor and heating element layer 40 includes multiple sensors 48, the sensors may be equally spaced along the length of the sensor and heating element layer 40.

[0036] The heating elements 50 provide heat to the contact member 42, which in turn provides heat to the hair in contact with the hair contact surface 37 of the contact member 42 when in use. In this example, the sensor and heating element layer 40 includes six heating elements 50, each of which includes a resistive track 51 and a pair of conductive pads (not shown). The resistive track 51 of each heating element 50 includes a material such as copper, silver, constantan, or stainless steel, and extends on the substrate 49 to define a generally U-shaped resistive track 51, wherein the conductive pads are located at either end of the resistive track 51. The resistive track 51 can be formed by a process such as etching or printing. However, in other examples, one or more heating elements 50 can be formed by a length of wire. Furthermore, in other examples, the sensor and heating element layer 40 can include more or fewer heating elements 50.

[0037] In this example, the heating element 50 takes the form of a thick film printed heater trace, but other forms of heating elements may be used, such as foil heaters, thin film heaters, tubular heating elements, etched heaters or coil heating elements.

[0038] The heating elements 50 extend together on the base 49 such that the heating elements 50 together cover about 25% of the area Ac defined by the hair contacting surface 37 of the contact member 42 and span about 80% of the length Lc defined by the hair contacting surface 37 of the contact member 42. In other examples, these percentage values ​​may vary, and in fact the heating elements 50 may preferably together cover no less than 50% of the area Ac defined by the hair contacting surface 37 and span no less than 95% of the length Lc defined by the hair contacting surface 37. In this way, a more even distribution of heat may be provided across the contact member 42 and the hair contacting surface 37.

[0039] Each resistive track 51 is located beneath a different heating zone 55 of the contact member 42, so that each heating element 50 heats a corresponding heating zone 55 of the contact member 42 and thus a corresponding heating zone of the hair contact surface 37. Figure 5 In this example, there are six heating elements 50, which are arranged along the length L of the contact member 42. c The contact member 42 is evenly spaced, divided into six heating zones 55 of equal length, and the heater assembly 34 is a six-zone heater. When in use, the power supplied to each heating element 50 can be independently controlled. Specifically, the hair care appliance 10 may include a controller (not shown) configured to independently control the power supplied to each heating element 50, so that different amounts of power can be supplied to each heating element 50. This allows for more precise control of the temperature of the hair contact surface 37.

[0040] Sensor 48 senses or measures the temperature of heater assembly 34 and provides an indication of the temperature of hair contacting surface 37 of contact member 42. That is, although sensor 48 does not directly measure the temperature of hair contacting surface 37 in this example, the temperature sensed or measured by sensor 48 provides a good approximation of the temperature at hair contacting surface 37.

[0041] In this example, sensor 48 comprises a thermistor connected to a pair of wires, but in other examples, sensor 48 may take a different form, such as a thermocouple. In some examples, sensor 48 may be a printed film sensor.

[0042] like Figure 5As shown, sensor 48 is located between (and spaced apart from) parallel portions of resistive traces 51 of adjacent heating elements 50 on a central portion of substrate 49 so as to be located along the center of length Lc defined by hair contact surface 37 of contact member 42. Thus, sensor 48 is arranged to sense the temperature of hair contact surface 37 at a central location along its length Lc. However, in other examples, sensor 48 may be disposed at different locations on substrate 49 so as to sense the temperature at different locations on hair contact surface 37. Furthermore, sensor and heating element layer 40 may include multiple sensors 48 disposed at different locations on substrate 49 to allow for multiple temperature measurements at different locations on hair contact surface 37. In examples where sensor and heating element layer 40 includes multiple sensors 48, these sensors 48 may be positioned on sensor and heating element layer 40 so as to be equally spaced apart from one another. This arrangement advantageously allows for the temperature of hair contact surface 37 to be measured at multiple locations along the length of contact member 42. This temperature information may be used to determine whether the amount of heat supplied to contact member 42 from one or more heating elements 50 should be adjusted. For example, if one of the sensors 48 measures a temperature that is lower than the desired temperature of the hair contacting surface 37, the power supplied to the associated heating element 50 may be adjusted to supply more heat to its associated heating zone 55 so as to correspondingly increase the temperature of its associated heating zone 55. As already noted, one or more sensors 48 may be provided on a different layer than the heating elements 50.

[0043] Figure 8 and Fig. 9 Alternative examples of sensor and heating element layers 140 and 240 that may be used in the hair care appliance 10 are shown. In these examples, the sensor and heating element layers 140, 240 include a plurality of heating elements 150, 250 and a plurality of sensors 148, 248, each sensor 148, 248 being associated with one of the heating elements 150, 250, respectively.

[0044] Figure 8 The sensor and heating element layer 140 includes three heating elements 150 and three associated sensors 148. Each heating element 150 includes a concentric rectangular shaped resistive track 151 and a pair of conductive pads 153 for independently supplying power to each of the resistive tracks 151. Figure 5 As shown in the example of FIG. 1 , each of the resistive tracks 151 is located under a different area of ​​the contact member 42 so that each heating element 150 heats a corresponding area of ​​the contact member 42, thereby heating the hair contact surface 37. Figure 5 As shown in the example of FIG. 1 , in use, the power supplied to each heating element 150 can be independently controlled to allow more precise control of the temperature of the hair contacting surface 37 to be achieved.

[0045] Fig. 9 The sensor and heating element layer 240 includes six heating elements 250 and six associated sensors 248, each sensor being located approximately in the center relative to its associated heating element 250. Each heating element 250 includes a resistive track 251 extending in a serpentine pattern on the substrate 49 and a pair of conductive pads 253 (for clarity, the two are not shown in FIG. Fig. 9 Only two of them are labeled in the figure), which are used to independently supply power to each of the resistor tracks 251.

[0046] exist Fig. 9 In the example of FIG. 2 , the resistive track 251 of each heating element 250 has a thickness of about 0.015 mm, a width of about 1.0 mm, and a spacing between adjacent parallel portions of the track 251 of about 0.5 mm. When the parallel portions of the track 251 are separated by the associated sensor 248, the spacing between the portions of the track 251 at each side of the sensor 248 is greater than 0.5 mm to accommodate the sensor 248. In other examples, different track thicknesses, widths, and spacings may be used to achieve the desired coverage of the hair contact surface 37. Furthermore, in other examples, the track thicknesses, widths, and spacings may be different between different heating elements 50.

[0047] like Figure 5 and 8 As shown in the example of FIG. 4 , each resistive track 251 is located under a different area of ​​the contact member 42, so that each heating element 250 heats a corresponding area of ​​the contact member 42, thereby heating a corresponding area of ​​the hair contact surface 37. Figure 5 and Figure 8 As shown in the example of FIG. 3 , in use, the power supplied to each heating element 250 can be independently controlled to allow more precise control of the temperature of the hair contacting surface 37 to be achieved.

[0048] Figure 8 and Fig. 9 Multiple sensors 148 and 248 of the example allow the temperature of each area of ​​hair contact surface 37 to be determined. This enables better control of the temperature of hair contact surface 37 to obtain better styling results. In addition, controlling the temperature of different areas of hair contact surface 37 helps to avoid overheating of hair contact surface 37, thereby reducing the possibility of damage to hair in contact with hair contact surface 37 during use.

[0049] Now back to Figure 6 The electrical insulation layer 41 of the heater assembly 34 includes a first layer 56 and a second layer 58. The electrical insulation layer 41 is disposed between the sensor and heating element layer 40 and the contact member 42 so as to allow the contact member 42 to be electrically connected to the heating element 50 ( Figure 6(not shown) to ensure safety. Figure 5 and Figure 6 In the orientation shown, the first layer 56 is located directly above the sensor and heating element layer 40, and the second layer 58 is located directly above the first layer 56 and directly below the contact member 42. In this example, the first layer 56 and the second layer 58 are both formed of a glass-based dielectric material and each have a thickness of 0.0175 mm. However, it should be understood that other materials and thicknesses of the electrically insulating layer 41 and any constituent layers of the electrically insulating layer 41 may electrically isolate the contact member 42 from the heating element 50. For example, in some cases, materials such as prepreg or polyimide may be used in the electrically insulating layer 41.

[0050] The thickness of the electrical insulating layer 41 and the material(s) of the electrical insulating layer 41 both affect the thermal resistance of the electrical insulating layer 41. Generally speaking, for a given material, a thicker electrical insulating layer 41 has a higher thermal resistance. An electrical insulating layer 41 with a higher thermal resistance is more resistant to heat transfer therethrough. Therefore, a thicker electrical insulating layer 41 can reduce the amount of heat 37 reaching the contact member 41 and the hair contact surface. This should be taken into account when selecting the thickness and material(s) of the electrical insulating layer 41.

[0051] The contact member 42 is arranged on top of the electrically insulating layer 41 so as to Figure 5 The orientation shown is above the electrically insulating layer 41. In this way, the hair contacting surface 37 defines the outer surface of the heater assembly 34 and is arranged to contact and heat hair received between the arms 12, 14 of the hair care appliance 10 for styling in use.

[0052] The contact member 42 includes a heat dissipation layer 60. Figure 7 Shown separately in.

[0053] In this example, the contact member 42 is entirely defined by the heat dissipation layer 60, but in other examples, the heat dissipation layer 60 may only form a portion of the contact member 42. Figure 7 As shown, the heat dissipation layer 60 includes six equal lengths (L hz ) of the heating zones 55. As already explained, each heating zone 55 is associated with a respective heating element 50 located below the heating zone 55. It should be noted that the boundary lines 57 between the heating zones 55 are shown on the heat dissipation layer 60 only for illustration purposes and do not indicate different sections of the heat dissipation layer 60, which in this case is defined by a continuous layer of material.

[0054] Heat sink layer 60 is arranged and configured to diffuse heat provided by heating elements 50 of sensor and heating element layer 40 through contact member 42 and onto hair contact surface 37 of contact member 42 to provide a more uniform temperature distribution across hair contact surface 37. Heat sink layer 60 is particularly configured to provide a more uniform distribution of heat from sensor and heating element layer 40 across length Lc of hair contact surface 37.

[0055] Achieving a more uniform temperature distribution over the length Lc of the hair contact surface 37 is advantageous because it allows hair engaged at different locations along the length Lc of the hair contact surface 37 to be more consistently styled as the hair care appliance 10 is pulled along the length of the hair in use. Furthermore, improving the uniformity of temperature over the hair contact surface 37 advantageously reduces the temperature of any hot spots that may occur on the hair contact surface 37 during use. This reduces the likelihood of hair damage due to excessive temperatures in hot spot areas of the hair contact surface 37 and improves the safety of the hair care appliance 10.

[0056] To achieve a more uniform temperature distribution on the hair contacting surface 37, the heat sink layer 60 has a lateral thermal resistance R of no greater than 22 Kelvin / Watt.

[0057] The thermal resistance of a material is a measure of its ability to resist the transfer of heat.

[0058] The lateral thermal resistance R of the heat dissipation layer hsl is the thermal resistance experienced when heat propagates through the heat dissipation layer in the lateral direction x, which is defined as:

[0059] R hsl = L hsl / (k hsl * A hsl ) Formula 1

[0060] In formula 1, L hsl is the length that heat travels from the heating element 50 in the heat dissipation layer 60 in the lateral direction x, defined as the length L of the heating zone 55 hz Half of L hsl =L hz / 2. With this definition, it should be understood that the length L hsl It depends on the total length Lt of the heat dissipation layer and the number of heating elements 50 and corresponding heating areas 55 .

[0061] A hsl is the cross-sectional area of ​​the heat sink, k hsl is the thermal conductivity of the heat sink. Figure 7 In the example, the heat dissipation layer 60 has a rectangular cross section, and the cross-sectional area A hsl Defined as the thickness of the heat dissipation layer t hslMultiply by the width w of the heat sink hsl , that is, A hsl =w hsl *t hsl However, the cross-sectional area A hsl This will of course vary depending on the shape of the cross-sectional area, which is not limited to square or rectangular.

[0062] It can be understood from equation 1 that for a given number of heating elements 50 and associated heating zones 55, and a given length L t and width w hsl The heat sink layer 60 may be made of a material having an appropriate thermal conductivity and thickness to provide a lateral thermal resistance not exceeding 22 Kelvin / Watt.

[0063] However, if the heat sink layer 60 is too thick, the flexibility of the heat sink layer 60 is reduced, which in turn reduces the flexibility of the contact member 42 and the ability of the hair care appliance 10 to achieve a wrap-around, where hair is gathered and styled between the arms 12, 14 during use. In addition, a thicker heat sink layer 60 results in a slower thermal response of the contact member 42, and therefore causes the contact member 42 to heat and cool slower in response to changes in heat provided by the sensor and heating element layer 40.

[0064] Therefore, a thinner heat dissipation layer 60 may be preferred to provide better wrapping flexibility for the contact member 42 and to provide an adaptive hair styling mode, such as a "root to tip" mode, in which the temperature of the hair contact surface 37 changes dynamically as the hair care device 10 is pulled from the root to the tip of the hair. Specifically, the thickness of the heat dissipation layer 60 is preferably no greater than 0.500 mm, more preferably no greater than 0.200 mm.

[0065] Now refer to it again Figure 6 In this example, the heat dissipation layer 60 integrally defines the contact member 42, and itself includes a lower layer 62, an intermediate layer 64, and an upper layer 66. The lower layer 62, the intermediate layer 64, and the upper layer 66 are combined together to define a single self-supporting layer, namely the heat dissipation layer 60. The lower layer 62 and the upper layer 66 are each made of stainless steel, and the intermediate layer 64 is made of copper, so that the heat dissipation layer 60 is defined by a stainless steel and copper ternary metal material, which is a sandwich of stainless steel (in this example, copper and stainless steel). The thermal conductivity k of the stainless steel and copper ternary material of this example is hsl The lower layer 62, the middle layer 64 and the upper layer 66 each have a thickness of 0.0333 mm, so that the heat dissipation layer 60 of this example has a total thickness t of about 0.100 mm. hsl Therefore, in this example, the total length Lt of the heat dissipation layer is 90 mm, and the width w of the heat dissipation layer is hslThe heat dissipation layer 60 includes six heating regions 55 of equal length, and the heat dissipation layer has a lateral thermal resistance R of about 17 Kelvin / Watt. hsl .

[0066] As mentioned above, the lateral thermal resistance R of the heat dissipation layer 60 hsl In other examples, the temperature may be different, but it should not exceed 22 K / W. Therefore, the material and thickness t of the heat dissipation layer 60 are hsl Can be used with Figure 6 The examples are different, as long as the lateral thermal resistance R hsl For flexibility, the thickness t of the heat dissipation layer 60 is hsl It is best not to exceed 0.5mm.

[0067] The total maximum power supplied to the heating element 50 does not exceed 500 W. This maximum power limit ensures that the heater assembly 34 can effectively manage and dissipate the heat from the heating element 50 so that the temperature at any location on or in the heater assembly 34 (including at the hair contact surface 37) does not exceed a predetermined upper temperature limit. In this example, the upper temperature limit is selected to be 250° C. to avoid hot spots in the heater assembly 34 and on the hair contact surface 37. If the temperature of any part of the heater assembly 34 exceeds 250° C., it is considered that a hot spot exists.

[0068] exist Figure 6 In the specific example of FIG. 5 , the total maximum power supplied to the heating elements 50 is approximately 228 W, and the maximum power of each heating element 50 is approximately 38 W. At this maximum power consumption, the maximum temperature at any position on the hair contact surface 37 is approximately 240° C. Therefore, the temperature of the hair contact surface 37 does not exceed the upper temperature limit of 250° C., thereby avoiding the occurrence of hot spots on the surface 37 in contact with the hair.

[0069] It should be understood that the maximum power limit may vary depending on the material, thickness, and configuration of the heat dissipation layer 60 .

[0070] Turning now to other examples, the heat dissipation layer 60 may be formed entirely of copper or entirely of pyrolytic graphite. Thus, the heat dissipation layer 60 may be formed as a single layer, rather than as a Figure 6 as in the example of FIG. 1 .

[0071] In a specific example, the heat dissipation layer 60 may be formed entirely of copper and have a thickness t of 0.100 mm. hsl , and a lateral thermal resistance R of 7.7 K / W hsl In other specific examples, the heat dissipation layer 60 may be formed entirely of copper and have a thickness t of 0.400 mm. hsl , and a lateral thermal resistance R of 1.9 K / Whsl .

[0072] In a specific example, the heat sink layer 60 may be entirely defined by a sheet of pyrolytic graphite glued or otherwise adhered to the underside of the plate of the contact member 42. In these cases, the heat sink layer 60 does not contact the hair when in use, and the plate defines the hair contacting surface 37 of the contact member 42. The plate of the contact member 42 may be formed of, for example, stainless steel, and the heat sink layer 60 may have a thickness t of 0.100 mm. hsl and a lateral thermal resistance R of 4.3 K / W hsl In other specific examples, the heat dissipation layer 60 defined by the pyrolytic graphite sheet may have a thickness t of 0.017 mm. hsl and a lateral thermal resistance R of 10 K / W hsl .

[0073] It should be understood that for the heat dissipation layer 60, the thickness of copper and pyrolytic graphite may also be other than the above thicknesses, as long as the associated lateral thermal resistance R hsl Not exceeding 22 K / W.

[0074] It should be noted that although Figure 6 In the example of FIG. 4 , the heat sink layer 60 completely defines the contact member 42, but in other examples, the heat sink layer 60 may only form a portion of the contact member 42, such as in the above-mentioned example where the pyrolytic graphite is bonded below the plate of the contact member 42. In these cases, the heat sink layer 60 may be disposed anywhere between the hair contact surface 37 and the sensor and heating element layer 40. For example, the contact member 42 may include a stainless steel plate that defines the hair contact surface 37, and the heat sink layer 60 may be disposed directly below the stainless steel plate, such that the heat sink layer 60 is disposed on the inner surface of the stainless steel plate opposite the hair contact surface 37. In other examples, the heat sink layer 60 may be disposed below the electrically insulating layer 41, or above the electrically insulating layer 41, such as Figure 6 In the case where the electrically insulating layer 41 is defined by a plurality of layers 56 , 58 , the heat dissipation layer 60 may be located between the layers of the electrically insulating layer 41 .

[0075] As previously mentioned, the heat dissipation layer 60 advantageously improves the heat distribution on the hair contact surface 37, thereby reducing the possibility of forming hot spots on the hair contact surface 37, which in turn reduces the risk of hair damage caused by overheating and improves the safety of the hair care device 10. This is achieved by using a material or material combination with suitable thermal conductivity as the heat dissipation layer 60 and selecting an appropriate thickness of the heat dissipation layer 60 so that for a given length L of the heat dissipation layer 60, t and width w hsl , and a given number of heating zones 55, providing a lateral thermal resistance R not exceeding 22 K / W hsl .

[0076] In known arrangements, a plate formed of, for example, stainless steel, aluminum, copper or brass is used as the contact member, and relatively uniform heat distribution is achieved by using a relatively thick plate, typically on the order of 2-3 mm thick. However, such relatively thick sheet materials are typically not flexible enough to provide a containment effect and therefore fail to provide the functionality and styling capabilities of a hair care appliance 10 having a thinner contact member.

[0077] The present invention advantageously enables even heat distribution across the hair contacting surface 37 without the use of thick contact member plates that would impede flexibility and reduce the styling capabilities of the hair care appliance 10 .

[0078] While specific examples and embodiments have been described thus far, it should be understood that these are illustrative only and that various modifications may be made without departing from the scope of the invention as defined by the claims.

Claims

1. A heater assembly for a hair care appliance, the heater assembly comprising: a contact member defining a hair contact surface, wherein the contact member includes a heat sink layer; and one or more heating elements for heating the contact member; The heat dissipation layer has a lateral thermal resistance of no greater than 22 Kelvin / Watt. 2 . The heater assembly according to claim 1 , wherein the heat dissipation layer has a thickness of not more than 500 μm. 3 . The heater assembly according to claim 2 , wherein the heat dissipation layer has a thickness of not more than 200 μm.

4. A heater assembly according to any one of the preceding claims, wherein the heat sink layer is formed from a ternary metal material of stainless steel and copper, copper or pyrolytic graphite.

5. The heater assembly according to any one of the preceding claims, wherein the contact member comprises a stainless steel plate, and wherein the heat sink layer is provided on a surface of the stainless steel plate.

6. A heater assembly according to any preceding claim, wherein at least one of the heating elements comprises a thin film heater.

7. A heater assembly according to any preceding claim, wherein the heating elements together cover no less than 50% of the area of ​​the hair contacting surface of the contact member.

8. A heater assembly according to any preceding claim, wherein the heating elements together extend across no less than 95% of the length of the hair contacting surface of the contact member.

9. The heater assembly of any one of the preceding claims, wherein the heater assembly has a thermal conductivity of less than 0.004 JK -1 .mm -2 The heat capacity per unit area.

10. A heater assembly according to any preceding claim, comprising a plurality of heating elements.

11. A heater assembly according to any preceding claim, wherein the heating elements together draw no more than 500 W of power from a power source for heating the contact member.

12. A hair care appliance comprising a heater assembly according to any preceding claim.

13. The hair care appliance of claim 12, comprising a controller configured to control the power supplied to each of the heating elements.

14. The hair care appliance of claim 12 or 13, wherein the heater assembly comprises at least one electrically insulating layer located between the heating element and the contact member.

15. The hair care appliance of any one of claims 12 to 14, wherein the heater assembly comprises one or more sensors for indicating the temperature at one or more locations of the contact member.

16. The hair care appliance of claim 15, wherein the controller is configured to control the power supplied to each of the heating elements based on the temperature indicated by the one or more sensors.

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