FIELD

[0001] The present application generally relates to hair care appliances and, in particular, to a cordless curling iron that easily converts into a curling wand.

BACKGROUND

[0002] Curling irons are common hair care appliances. Most curling irons are corded, since the heating element draws a high current and needs a significant power source. Attempts have been made to produce cordless curling irons that are butane-powered, but these often fail to achieve a high enough temperature to be useful. Gas-powered curling irons are also considered more inherently dangerous and would be prohibited in some situations, such as on airplanes.

[0003] Another common hair care appliance is a curling wand. Individuals or hair care professionals typically have both a curling iron and a curling wand since each appliance is used to achieve a different stylistic effect. When traveling, this means that both appliances must be carried if a full range of hair styling options is desired.

[0004] It would be advantageous to provide for an improved cordless hair care appliance that, at least in part, addresses some of the shortcomings of existing hair care appliances.

BRIEF DESCRIPTION OF THE DRAWINGS [0005] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:

[0006] FIG. 1 shows a perspective view of one example embodiment of a hair care appliance configured to operate in a curling wand mode;

[0007] FIG. 2 shows the hair care appliance of FIG. 1 in a partially-exploded view; [0008] FIG. 3 shows a perspective view of another example embodiment of a hair care appliance in a partially-exploded view;

[0009] FIG. 4 shows, in block diagram form, one example of the electrical components of an embodiment of a battery-powered hair care appliance;

[0010] FIG. 5 shows, in longitudinal cross-section, at least a portion of the barrel of a hair care appliance;

[0011] FIG. 6 shows a close-up view of a further example embodiment of a hair care appliance;

[0012] FIG. 7 shows a close-up view of the further example embodiment of the hair care appliance with its removable clamp in place;

[0013] FIG. 8 shows a close-up view of the interior surface of an example removable clamp; and

[0014] FIG. 9 shows an example pair of heating elements for a hair care appliance.

[0015] Similar reference numerals may have been used in different figures to denote similar components.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0016] Various examples and aspects of the present application will be described with reference to the details discussed herein. The following description and drawings are illustrative of the present application and are not to be construed as limiting the present application. Numerous details are described to provide a thorough understanding of various embodiments. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of the embodiments of the present application. It will also be appreciated that various aspects and features may be implemented in sub-combinations, and that an aspect or feature from one described embodiment may be incorporated into other described embodiments. [0017] The present application describes, in some examples, a battery-powered hair care appliance that functions as both a curling iron and a curling wand. A removable clamp on a ring may be slid onto or off of the barrel to convert the appliance between iron and wand.

[0018] In one aspect, the present application describes a hair care appliance that includes a main body housing electrical components, including a battery and a processing unit. The appliance includes a barrel attached to and extending from the main body and having a heat conductive exterior surface, the barrel having an outer diameter, wherein an interface between the main body and the barrel includes an enlarged diameter portion axially aligned with the barrel and having an exterior surface diameter greater than the outer diameter, and removable clamp having a ring portion sized to slidably fit over the barrel and, on an outer face of the ring portion, a hinged clamp extending in an axial direction along the barrel and spring-biased to be urged against the barrel. The ring portion has an inner diameter sized to friction fit when slid along the barrel to the enlarged diameter portion.

[0019] In another aspect, the present application describes a hair care appliance that includes a main body housing electrical components, including a battery and a processing unit; a barrel attached to and extending from the main body and having a heat conductive exterior surface, the barrel having an outer diameter, wherein an interface between the main body and the barrel includes an enlarged diameter portion axially aligned with the barrel and having an exterior surface diameter greater than the outer diameter; removable clamp having a ring portion sized to slidably fit over the barrel and, on an outer face of the ring portion, a hinged clamp extending in an axial direction along the barrel and spring-biased to be urged against the barrel; and retention means for resisting axial movement of the removable clamp when slid onto the barrel to a point proximate the interface.

[0020] In yet a further aspect, the present application describes a cordless hair care appliance. The appliance may include a main body to serve as a handle, the main body including a plug socket to receive a connector from a DC adaptor that supplies a DC input current; a barrel attached to and extending from the main body and being formed from a heat conductive material, the barrel containing a heating element in contact with an inner surface of the barrel to heat the barrel through conduction; a battery housed within the main body, the battery including at least two lithium ion batteries electrically connected in series, the battery supplying a heating current; a microcontroller; a battery charge circuit to receive the DC input current from the plug socket and to, under control of the microcontroller, recharge the battery when the heating element is not in use; and a first switch under control of the microcontroller and connecting the battery to the heating element to supply the heating current to the heating element. The heating element may include two or more heating coils connected in parallel and pressed against the inner surface of the barrel.

[0021] Other aspects and features of the present application will be understood by those of ordinary skill in the art from a review of the following description of examples in conjunction with the accompanying figures.

[0022] In the present application, the terms“comprises” and“comprising” are intended to be inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms“comprises” and“comprising” and variations thereof mean the specified features, steps, or components are included. These terms are not to be interpreted to exclude the presence of other features, steps, or components.

[0023] In the present application, the term“exemplary” means“serving as an example, instance, or illustration”, and should not be construed as preferred or advantageous over other configurations disclosed herein.

[0024] In the present application, the terms“about”,“approximately”, and“substantially” are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions. In a non-limiting example, the terms “about”,“approximately”, and“substantially” may mean plus or minus 10 percent or less.

[0025] In the present application, the term“and/or” is intended to cover all possible combinations and sub-combinations of the listed elements, including any one of the listed elements alone, any sub-combination, or all of the elements, and without necessarily excluding additional elements.

[0026] In the present application, the phrase“at least one of ...or.. is intended to cover any one or more of the listed elements, including any one of the listed elements alone, any sub- combination, or all of the elements, without necessarily excluding any additional elements, and without necessarily requiring all of the elements.

[0027] There are a number of hair care appliances used to style hair, including curling irons, curling wands, and hair straighteners, among others. Both curling irons and curling wands features a cylindrical heated barrel, but the curling iron further includes a clamp to press locks of hair against the barrel, allowing for tighter curls to be imparted to the locks. Straighteners feature flat-surfaced heated jaws between which locks of hair can be clamped in order to remove curl. All three of these examples contain heating elements that cause a heat-conductive portion of the appliance to become hot during use. To power the heating element, these devices tend to draw large currents and rely on a corded power connection to conventional power outlets. Moreover, each device is designed for a different purpose and those users that which to achieve different hair care looks typically own at least one of each of these devices.

[0028] In accordance with one aspect of the present application, a hair care appliance is provided that functions as both a curling iron and a curling wand and is easily converted between iron and wand modes of operation.

[0029] In another aspect of the present application, a hair care appliance is provided that operates in both battery-powered and wall-plug powered modes. In particular, in some implementations, the wall-plug is a DC power supply, such as through a plug-in AC/DC adaptor. This DC power supply is sufficient to recharge the internal battery over time, but insufficient to power the hair care heating element on its own. In some instances, the DC power supply comes from a USB-connection or some other similar DC current source, as opposed to an AC/DC adaptor plugged into the power mains.

[0030] Accordingly, when plugged in to the DC power supply, the heating element draws current from both the DC power supply and the internal battery when heating. When not heating the element, the DC power supply recharges the internal battery. In some embodiments, an internal power sensor determines whether the appliance is receiving power via a DC power supply and, if not, then it relies solely on battery power for heating the appliance and, otherwise, relies on both the DC power supply and the internal battery for current to heat the heating element.

[0031] Reference is now made to Figure 1, which shows one example of a hair care appliance 10. The appliance 10 features a generally cylindrical main body 12 and an axially- aligned generally cylindrical barrel 14. The main body 12 serves as a handle and houses the battery, a processing unit, and associated circuitry. The barrel 14 is formed from a heat- conductive metal, whereas the main body 12 may be formed from a generally heat-insulated material so that the heat generated by a heating element does not heat the main body 12.

[0032] The main body 12 may include user interface elements, such as an input device 16 and a display device 18. In this example, the display device 18 includes at least a numeric display for indicating a temperature setting or reading. The display device 18 may be an LCD screen or the like. The input device 16 in this example includes a power on/off button 20, a temperature up button 22 and a temperature down button 24. The temperature up and down buttons 22, 24 may be used to set a target temperature. The available setting may be subject to some preset maximum or minimum values. Although Figure 1 depicts the power on/off button 20 and temperature up and down buttons 22, 24 arranged longitudinally along the shaft of the main body 12, it will be understood that they may be arranged in another manner on the main body 12, together or separately. For example, they may be arranged in an alignment transverse to the longitudinal axis of the main body 12 in some implementations.

[0033] The display device 18 may display a target temperature value when in a temperature setting mode, and may display a measured or actual temperature value when in a heating mode. The display device 18 may alternatively or additionally include other display elements such as LED lights for indicating modes of operation or other state information. In some instances, LED lights may be incorporated into the main body 12. In some instances, LED lights may be incorporated into the input device 16. For example the input device 16 or a portion of it may be illuminated. The colour of illumination may signal a state or mode of operation. For example, a particular colour, such as green, illuminating the power button 20 may signal that the appliance 10 is turned on. The LED lights may be pulsed or flash to signal other state or mode information, such as if the battery is being charged, or to signal a low battery state, or other such information.

[0034] The main body 12 may include an end cap 24 that is generally circular. The end cap may be friction fit, screwed in, or otherwise attached so as to secure the end of the main body 12 and retain one or more rechargeable batteries within an internal battery compartment (not illustrated). In some cases, the end cap 24 may be removable by an end user to facilitate easy replacement of the rechargeable batteries. In some other cases, the end cap 24 may be secured in place to prevent end-user access to the battery compartment.

[0035] In at least one example, the battery is a pair of batteries. In one example, the batteries are rechargeable lithium-ion batteries, including lithium cobalt oxide, lithium iron phosphate, lithium ion manganese oxide, lithium nickel manganese cobalt oxide, lithium-sulfur, or other lithium-based batteries. In other implementations, different battery constructions are used, such as, for example, lithium polymer. The selected batteries ideally have a relatively low internal resistance and are capable of outputting a high current. In one example, the batteries are connected in series to boost the terminal voltage. In a specific implementation, the batteries include two series connected 21700 form-factor lithium rechargeable cells, each with a nominal capacity of 4000m Ah and capable of withstanding a discharge current of up to 12 A. Each battery in this example has a terminal voltage that ranges from 4.2V at full charge down to 3.65V.

[0036] The main body 12 further includes a plug socket (not shown) for receiving a connector from an AC/DC adapter. The AC/DC adapter plugs into a wall socket and supplies DC power via its connector. The connector may be a coaxial connector in some examples. The DC power supplied by the AC adapter may be, for example, 9 Volts DC, although other implementations may use different voltage levels. In one example, a USB connector is used and at least 5VDC is supplied via the USB connection. In yet another example, a USB connector is used to obtain higher power (and higher voltage) in compliance with the USB Power Delivery Specification revision 3.0. In some implementations, the connector is a USB Type-C (“USB-C”) connector. With a suitable AC adapter and USB-C connector, a charging current of up to 3A at 9VDC may be supplied. In one example implementation, the AC adaptor and USB-C connector are configured to supply 2 A at 9VDC. [0037] The hair care appliance 10 further includes a removable clamp 30. The removable clamp includes a ring portion 32 and a hinged clamp 34 pivotably mounted to the ring portion 32. The hinged clamp 34 extends in an axial direction parallel to the barrel 14 and is spring-biased at the hinged area to urge the hinged clamp 34 against the outer surface of the barrel 14. The removable clamp 30 includes a lever 36 connected to the hinged clamp 34 and extending away from the hinged clamp 34. The lever 36 is positioned so as to be thumb-depressible in opposition go the spring-biasing, thereby pivoting the hinged clamp 34 up and away from the outer surface of the barrel 14.

[0038] The hinged clamp 34 may be constructed from a heat-conductive material such that heat generated for heating the barrel 14 is conductively transferred to the hinged clamp 34 when the hinged clamp 34 is in contact with the barrel 14. The lever 36 may be made, at least in part, from a non-heat-conductive material so that it does not heat up and can be touched by a user. The ring portion 32 may be made from heat-conductive material, non-heat-conductive material, or a combination thereof.

[0039] Reference is now also made to Figure 2, which shows the example hair care appliance 10 in exploded view. In this view, the removable clamp 30 is slid off the barrel 14. With the removable clamp 30 detached from the barrel 14, the appliance 10 may function as a curling wand, whereas with the removable clamp 30 attached it functions as a curling iron.

[0040] In some embodiments, the removable clamp 30 may incorporate a stand for the appliance 10. That is, the ring portion 32 may include a non-heat-conductive stand 40, formed as a projection from its underside. The projection may be a two-point projection with or without a relatively flat portion interconnecting the two-points. The projection extends from the outer surfaces of the ring portion 32 on a side opposite to the side of the ring portion 32 to which the hinged clamp 34 is pivotably attached.

[0041] In this example, the barrel 14 and the main body 12 meet at an interface. The barrel 14 has an outer diameter that is substantially constant along its length. The interface between the barrel 14 and the main body 12 includes an enlarged diameter portion having an exterior surface diameter greater than the outer diameter of the barrel 12. In this example, the enlarged diameter portion may be formed as a flared frustoconically-shaped outer surface 40. The enlarged diameter portion may function as a stop that prevents the removable clamp 30 from being slid onto the main body 12 and off of the barrel 14. In some examples, the flared frustoconically-shaped outer surface 40 may aid in friction fitting the removable clamp 30 when mounting, as the friction fit gets more secure as the ring portion 32 is advanced further onto the flared frustoconically-shaped outer surface 40. In yet other embodiments, the enlarged diameter portion may not be flared and may not be frustoconical in shape. In some embodiments, the enlarged diameter portion may be implemented as a projection or other non-annular element extending from the outer surface of the barrel 14 or the main body 12 proximate the interface so as to stop axial movement of the ring portion 32 in the direction of the main body 12. In such embodiments, the enlarged diameter portion may be referred to as a stop member.

[0042] In some examples, the barrel 14 may include an annular groove into which is fit a retaining ring 42 in a location proximate the interface. The retaining ring 42 may be slightly larger in its outer diameter than the outer diameter of the barrel 12, such that when in place in the annular groove, the thickness of the retaining ring 42 results in a slightly bulged annular part of the barrel 14. The retaining ring 42 may be formed from a heat-resistant material having a higher coefficient of friction than the material used to form the barrel 12. In use, the retaining ring 42 resists movement of the ring portion 32 once the removable clamp 30 is in place on the appliance 10, and resists both axial sliding of the removable clamp 30 and rotational movement of the removable clamp 30.

[0043] Some implementations of the appliance 10 may feature the retaining ring 42 or may feature the enlarged diameter portion, or may feature both or neither. In some implementations, alternative mechanisms may be used to retain the removable clamp 30 in position once slid onto the barrel 14 towards the interface.

[0044] In one example, the appliance 10 may feature the annular groove with no retaining ring 42. The ring portion 32 may include a projection on its inner surface sized to snap-fit into the annular groove. The projection may include an annular projection in the form of a rib that extends for substantially the full inner circumference of the inner surface. The projection may include a single point protuberance, i.e. a boss, or multiple such protuberances aligned along the inner circumferentially along the inner surface. The rib or boss/bosses may snap-fit into the groove when the ring portion 32 is slid into place proximate the interface. The rib or boss/bosses in cooperation with the groove may resist axial movement of the removable clamp 30.

[0045] Reference is now made to Figure 3, which shows another example embodiment of a hair care appliance 110. In this example, the appliance 110 includes a barrel 114 that features a shallow longitudinal channel 162. A removable clamp 130 has a ring portion 132 that features a projection 160 on its interior surface. The projection 160 is sized to fit within the channel 162, such that the removable clamp 130 may only be slid onto the barrel 114 when oriented correctly to rotationally align the projection 160 with the channel 162. This may prevent incorrect rotational movement of the removable clamp 130 in some implementations. The end of the channel 162 proximate the interface may include a ridge at the channel bottom over which the projection 160 is to snap-fit, or a deeper portion into which the projection 160 is to snap-fit so as to resist further axial movement of the removable clamp 130 once slid into place.

[0046] In some implementations, and as shown in this example, the channel 162 may further include a partial annular channel 164 at the end of the channel 162, into which the projection 160 is rotated. The partial annular channel 164 prevents axial movement of the removable clamp 130 once the projection 160 has been rotated into the partial annular channel 164. The partial annular channel 164 may feature a ridge at the channel bottom over which the projection 160 is to snap-fit, or a deeper portion into which the projection 160 is to snap-fit so as to resist further rotational movement of the removable clamp 130 once slid into place.

[0047] In this sense the barrel 114 and ring portion 132 are keyed to ensure correct rotational alignment and to prevent rotation and to prevent or resist axial movement once in place. It will be appreciated that the groove/channel combination may be switched such that the ring portion 132 features a groove and the barrel 114 features a projection in some implementations.

[0048] Yet a further embodiment is shown in Figures 6, 7 and 8. Figure 6 illustrates a close-up view of another embodiment of a hair care appliance 400. The hair care appliance 400 in this embodiment includes a connector section 402 between a barrel 404 and a handle 406. Figure 6 shows a removable clamp 410 slid partway down the barrel 404. Figure 7 shows the removable clamp 410 in place over the connector section 402. Figure 8 shows a close-up view of the removable clamp 410 and, in particular, an inner surface 414 of its ring 412.

[0049] In this example embodiment, the connector section 402, formed form a heat resistant material, features a main part 420 having a diameter substantially similar to the diameter of the barrel 404. The main part 420 is of a length at least as long as the length of the inner surface 414 of the ring 412 of the removable clamp 410, so that the entire ring 412 fits atop the main part 412 when in place. The connector section 402 further includes a stop 422 between the main part 420 and the handle 406. The stop 422 has a diameter larger than the main part 420 and in this example it is formed as a frustoconically-shaped part. In other examples, it may be an annular ridge or other formation. When the removable clamp 410 is slid onto the connector section 402, an edge of the ring 412 abuts the stop 422 to prevent further axial movement towards the handle, as shown in Figure 7.

[0050] Figure 8 shows the interior surface 414 of the ring 412 which, in this example, features a plurality of longitudinal ridges 424. The longitudinal ridges 424 provide a friction fit when slid over the connector section 410 main part 420. Alternatives to the longitudinal ribs 424 may be used. In another example, the ribs 424 are formed on the main part 420 to cause a friction fit with the ring 412 when the removable clamp 410 is in place.

[0051] The ring 412 of the removable clamp 410 further features a slot 430 at its end proximate the handle 406. A cooperating longitudinally-extending ridge 432 is formed on the connector section 402 extending from the stop 422 towards the barrel 404 atop the main part 420. When the removable clamp 410 is slid over the barrel 404 and onto the connector section 402, and is correctly rotationally aligned, the longitudinally-extending ridge 432 engages the slot 430 to prevent rotational movement of the removable clamp 410. The ribs 424 between the ring 412 and the main part 420 of the connector section 402, through friction fit, resist axial and longitudinal movement of the removable clamp 410.

[0052] Reference is now made to Figure 4, which shows, in block diagram form, an example of a cordless hair care appliance 200. The appliance 200 in this example includes a microcontroller 202 and a rechargeable battery 204. In this example, the rechargeable battery 204 includes at least two series-connected lithium-ion batteries having relatively low internal resistance and high current output. In one specific example implementation, the batteries are 21700 form-factor lithium rechargeable cells, each with a nominal capacity of 4000mAh and capable of withstanding a discharge current of up to 12A. Each battery in this example has a terminal voltage that ranges from 3.65V to 4.2V, giving an overall terminal voltage for the series connected batteries of 7.3 V to 8.4V.

[0053] The microcontroller 202 operates under program control to coordinate and control operation of the other components and circuitry in the appliance 200. The appliance 200 may include output devices, such as a display 210 and/or LED 212 indicators. The appliance 200 may further include input devices, such as a power on/off button 214 or switch, and a temperature up button 216 and a temperature down button 218. Signals from the buttons 214, 216, 218 may be provided, subject to suitable conditioning, to the microcontroller 202 for taking consequent action. One or more temperature sensors 220 may also provide sensor signals to the microcontroller 202 for regulating power supplied to a heating element dependent upon a current temperature setting. In some implementations, the appliance 200 may further incorporate additional components for safety purposes. For example, the microcontroller 202 may be connected to an inertial sensor (not shown), such as an accelerometer, to determine if the appliance 200 has been stationary for more than a threshold period of time while being switched on and heated. If so, then the microcontroller 202 may be configured to turn the appliance 200 off. Similarly, the appliance 200 may include a battery chamber temperature sensor (not shown) to monitor the temperature proximate the battery(ies) and to turn off the appliance 200 if the temperature exceeds a danger level.

[0054] The heating element may be one or more heating coils 228 positioned within the conductive barrel of the hair care appliance 200. In one implementation, two or more heating coils 228 are connected in parallel to lower the load resistance and to make best use of the peak discharge current for heating the barrel. In one implementation, the heating coils each have an internal resistance of less than 2 Ohms, resulting in a load resistance of less than 1 Ohm. In a specific example, the heating coils have an internal resistance of less than 1.4 Ohms, resulting in a load resistance of less than 0.7 Ohms. With a peak voltage of 8.4 V and a peak current of 12 A, a load resistance of about 0.7 Ohms permits maximum peak heat generation of the available 100 W of power.

[0055] A DC voltage plug socket 206 is provided to accept a connector from an AC adaptor to receive the DC power supply. In some embodiments the AC adaptor supplies 9 VDC, however it will be understood that the DC voltage supply may range from, for example, 5 VDC to 14 VDC depending on the adaptor selected. When the DC voltage plug socket 206 is connected to a DC power supply, in this example, 9 VDC is provided to a battery charge circuit 208 for recharging the battery 204 when the battery 204 is not being used to heat the appliance 200. The plug socket 206 is a USB-C connector socket in some implementations.

[0056] The battery charge circuit 208 may be implemented using a variety of possible configurations for recharging the battery 204 from an input DC supply current; however, in one example the battery charge circuit 208 may include a charge management control chip, such as the MCP73831 chip from Microchip Technology Inc. One or more of the LEDs 212 may be incorporated into the battery charge circuit 208 for signaling status of the charging operation, such as whether the battery 204 is charging or is fully charged. The microcontroller 202 may monitor the charges status and may cut off the charge current when the battery 204 has been fully charged. The microcontroller 202 may also cut off the charge current when the appliance 200 is in use and the DC mains supply from the plug socket 206 is being used to assist in powering the heating coils 228.

[0057] The heating coils 228 requires certain power characteristics in order to reach desired temperature levels. The microcontroller 202 may adjust the maximum temperature setting permissible dependent upon a number of factors, such as the current battery charge level and/or whether a connector from an AC adaptor is supplying current via the DC voltage plug socket 206. In some implementations, if the appliance 200 is relying on battery power alone, then the microcontroller 202 may impose a lower maximum temperature setting.

[0058] The heating coils 228 are directly coupled to the current supplied by the battery

204 via a power controller 224 operating under control of the microcontroller 202. To avoid efficiency losses, the power controller 224 avoids voltage conversion. The power controller 224 may further avoid efficiency losses by directly passing supply current from the battery 204 to the heating coils 224 through a simple switch that operates under control of the microcontroller 202. The switch may, in some embodiments, be a MOSFET switch. In some implementations, a signal from the microcontroller 202 may cause the switch to enter on/closed state to couple the battery terminals to the heating coils 228 when the microcontroller 202 determines from the on-state of the appliance 200, the selected temperature setting, and the temperature reading, that heating is required. In some implementations, dependent on the temperature setting and the temperature reading, the switch may be operated to control the average current supplied to the coils by pulsing the switch at a desired duty cycle.

[0059] The DC voltage supply received via the plug socket 206, when an AC/DC adaptor is connected to a mains supply, is coupled to the heating coils 208 via a second switch 222. The second switch 222 operates under control of the microcontroller 202. When the appliance 200 is on and the microcontroller 202 determines that the heating coils 228 are to be powered, and a DC voltage supply is available, then the microcontroller 202 causes the second switch 222 to connect the DC voltage supply to the heating coils 228 to supplement the current being drawn from the battery 204 to power the heating coils 228. As noted above, in some embodiments the DC supply is 9VDC and 2 A. This may boost the peak current available to about 14A in some examples, which may increase the peak power to the heating coils to about 135 W.

[0060] The microcontroller 202 may monitor and control the other elements of the appliance 200, including shutting down or powering off some elements in a power saving mode when operating on battery power, or when battery charge falls below a certain percentage, in order to better preserve battery life.

[0061] Reference is now made to Figure 5, which diagrammatically illustrates a cross- sectional view of an example barrel 302 of a cordless hair care appliance. The appliance may include a curling iron, a curling wand, or a combined curling iron and wand as depicted in connection with Figures 1 to 3. The barrel 302 in this example is formed from an aluminum tube 304 having an exterior coating 306 formed by plating the aluminum tube 304 with a suitably durable heat-conductive metal, such as titanium or a titanium alloy. The aluminum tube 304 is an efficient heat conductor that will provide a relatively uniformly heated barrel with fairly even heat distribution.

[0062] When the appliance is in use, the aluminum tube 304 is heated by electrically- insulated heating coils. In this example, the electrically-insulated heating coils include two heating coils electrically connected in parallel: a first heating coil 308a and a second heating coil 308b. In some examples, three or more heating coils may be connected in parallel. In the example shown in Figure 5, the coils 308a and 308b are shown interleaved. In such an embodiment, the coils 308a and 308b may be formed as electrical traces on a common flexible substrate. In another embodiment, shown in Figure 9, the heating coils may be formed by respective electrical traces on separate flexible substrates, which in this example are rectangular. Each substrate may be sized to have a width such that when folded into a semicircle, the pair of substrates form a cylindrical or nearly cylindrical tube within the inner surface of the aluminum tube.

[0063] Reference still being made to Figures 5 and 9, the heating coils 308 are positioned to be tightly coupled against the inner surface of the aluminum tube 304 so as to conduct generated heat directly to the aluminum tube 304. An inner core 310 presses the heating coils 308 against the inner surface of the aluminum tube 304. The inner core 310 is formed from a heat- resistant and low-heat-capacity material. The material selected for the inner core 310 may be reflective or have a heat reflective outer coating in some implementations. The inner core 310 material is selected to avoid absorbing heat from the heating coils. In one example, the inner core 310 is formed from a flame-retardant plastic. The material selected for the inner core 310 may be capable of retaining mechanical strength up to at least 250 °C. In one example, the inner core 310 is formed from polyphenylene sulfide (PPS) plastic. Although depicted as a solid cylindrical material, the inner core 310 may be a hollow cylinder or tube with open or closed ends in some examples.

[0064] It will be appreciated that the end of the barrel 302 closest the handle of the appliance is connected to the handle through a well-insulated neck piece that prevents heat transfer to the handle of the appliance. [0065] Certain adaptations and modifications of the described embodiments can be made.

Therefore, the above discussed embodiments are considered to be illustrative and not restrictive.