Hair styling appliance and method for operating same

Abstract

A hair styling appliance includes a first arm and a second arm, each of the first and second arms having a free end and a hinged end and coupled together at their respective hinged ends to allow the first and second arms to be movable between a closed position and an open position. The biasing device is configured to bias the first arm and the second arm toward the open position. Hair contact surfaces are provided at the free ends of the first and second arms, the hair contact surfaces facing each other, at least one of the hair contact surfaces being provided with a heater. The temperature-sensitive magnetic latch arrangement is configured to maintain the first and second arms in the closed position when a temperature of at least a portion of the magnetic latch is below a first threshold temperature, and to release the first and second arms from the closed position when the temperature of the at least a portion of the magnetic latch is above the first threshold temperature, to allow the biasing means to move the first and second arms to the open position.

Description

Technical Field

[0001] The present invention relates to a hair styling appliance and a method of operating a hair styling appliance. A heated hair styling appliance is intended to shape hair into a desired shape or style by the action of heat and mechanical pressure and / or air flow. Background Art

[0002] A straightening iron uses a heating plate attached to a pivoting arm, and a user can hold the heating plate in a closed position and sandwich a hair strand between the heating plates. Once the hair is heated above its transformation temperature, the hair strand can be shaped into different shapes.

[0003] During use of the appliance, the temperature of the heating plate is typically at least 160 °C and may be higher, such as at least 180 °C or at least 200 °C or even about 210 °C, which depends in part on the type of hair being styled. The appliance can be wired or wireless (battery-powered), and in either case, the heating plate is typically at ambient temperature before use. Therefore, there is usually a delay between turning on the appliance and the appliance reaching the desired operating temperature. In addition, after use, even when the power is turned off, the heating plate remains hot for some time.

[0004] For example, a known hair styling appliance is disclosed in WO2020 / 141295A1. Summary of the Invention

[0005] When a hair styling appliance of the type disclosed in WO2020 / 141295A1 is turned off, since the heating plate remains hot for some time, it is not easy for a user to determine whether the appliance can be safely stored, for example, in a handbag or a pocket. If the appliance is too hot, there is a risk of injury or a risk of damaging surrounding items.

[0006] The present invention has been designed in view of the above considerations.

[0007] The inventors have realized that it is particularly meaningful to use a device that does not require electric power to indicate that the appliance is at a safe storage temperature.

[0008] In a first aspect, the present invention provides a hair styling appliance, comprising:

[0009] a first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end and being connected together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position;

[0010] a biasing device configured to bias the first arm and the second arm towards the open position;

[0011] A hair contact surface, provided at the free ends of the first arm and the second arm, the hair contact surfaces facing each other, at least one of the hair contact surfaces being provided with a heater; and

[0012] A temperature-sensitive magnetic latch device configured to hold the first arm and the second arm in a closed position when at least a portion of the magnetic latch is below a first threshold temperature and to release the first arm and the second arm from the closed position when the at least a portion of the magnetic latch is above the first threshold temperature to allow a biasing device to move the first arm and the second arm to an open position.

[0013] In a second aspect, the present invention provides a method of operating a hair styling appliance, the hair styling appliance comprising:

[0014] A first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end and being coupled together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position;

[0015] A biasing device configured to bias the first arm and the second arm towards the open position;

[0016] A hair contact surface, provided at the free ends of the first arm and the second arm, the hair contact surfaces facing each other, at least one of the hair contact surfaces being provided with a heater; and

[0017] A temperature-sensitive magnetic latch device,

[0018] wherein the method comprises the steps of:

[0019] Switching on a power supply to heat the heater, wherein the magnetic latch device holds the first arm and the second arm in the closed position while at least a portion of the magnetic latch is below the first threshold temperature; and

[0020] When the at least a portion of the magnetic latch is above the first threshold temperature, the magnetic latch releases the first arm and the second arm from the closed position and the biasing device moves the first arm and the second arm to the open position, thereby indicating that the device is heating up in preparation for use.

[0021] In a third aspect, the present invention provides a method of operating a hair styling appliance, the hair styling appliance comprising:

[0022] A first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end and being coupled together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position;

[0023] A biasing device configured to bias the first arm and the second arm towards the open position;

[0024] A hair contact surface, disposed at free ends of the first arm and the second arm, the hair contact surfaces facing each other, at least one of the hair contact surfaces being provided with a heater; and

[0025] A temperature-sensitive magnetic latch device,

[0026] wherein the method comprises the following steps:

[0027] The user uses a heating plate to style hair;

[0028] When the temperature of at least a part of the magnetic latch is higher than a first threshold temperature, the magnetic latch cannot overcome the pushing force of the biasing device to hold the first arm and the second arm in the closed position, cutting off the power supply of the heater, so that the heating plate cools, and the said at least a part of the magnetic latch cools below the first threshold temperature; and

[0029] The user overcomes the pushing force of the biasing device to close the first arm and the second arm to the closed position and the magnetic latch holds the first arm and the second arm in the closed position, thereby indicating that the appliance is ready for storage.

[0030] Therefore, in the first to third aspects of the present invention, the temperature-sensitive magnetic latch device can both provide a device for holding the first arm and the second arm in the closed position when the appliance is properly cooled, and provide a device for allowing the first arm and the second arm to move to the open position to indicate that the appliance is above the threshold temperature. Advantageously, the temperature-sensitive magnetic latch device does not require electrical power.

[0031] The heater can be in the form of an electric heater, such as a resistive heater. The heater can be provided as a part of the hair contact surface of at least one arm, or can be provided in thermal contact with the hair contact surface. In some embodiments, the hair contact surface is the face of a plate. The plate can be a flexible or non-flexible hair contact plate. The temperature-sensitive magnetic latch device can be arranged in thermal contact with the heater, for example via the plate. In this way, it can be ensured that the temperature of the magnetic latch is close to the temperature of the hair contact surface of the appliance.

[0032] The temperature-sensitive magnetic latch device can include a temperature-sensitive magnetic element having a Curie temperature, such that:

[0033] (i) When the temperature of the temperature-sensitive magnetic element is below the first threshold temperature, the temperature-sensitive magnetic element is ferromagnetic, and

[0034] (ii) When the temperature of the temperature-sensitive magnetic element is higher than the first threshold temperature, the temperature-sensitive magnetic element is non-ferromagnetic.

[0035] When the temperature of the temperature-sensitive magnetic element is higher than the first threshold temperature, the temperature-sensitive magnetic element can be paramagnetic.

[0036] The Curie temperature of the temperature-sensitive magnetic element can be in the range of 50 - 150 °C. The lower limit of this range can be selected as 60 °C, 70 °C, 80 °C or 90 °C. The upper limit of this range can be selected as 140 °C, 130 °C, 120 °C or 110 °C. Different applicable ranges of the Curie temperature use different endpoints independently selected from the disclosed lower and upper limits. Considering the availability of suitable materials having this Curie temperature, a particularly suitable Curie temperature for the temperature-sensitive magnetic element is about 100 °C. Such materials can be used in household appliances such as cooking appliances, etc., where the Curie temperature corresponds to the boiling point of water, and this temperature reasonably indicates the appropriate threshold temperature of the current hair styling appliance.

[0037] Materials suitable for the temperature-sensitive magnetic element include nickel-copper-based alloys, such as Monel TM . For example, the temperature-sensitive magnetic element can be formed from an alloy consisting of 52 - 67 wt% Ni, 27 - 34 wt% Cu, and the balance optionally Fe, Mn, Si, Al, Ti, and / or C, as well as incidental impurities.

[0038] The temperature-sensitive latching device can include a first magnetic element on a first arm and a second magnetic element on a second arm. The first magnetic element can include a permanent ferromagnet, and the second magnetic element can include a soft ferromagnetic material.

[0039] In some embodiments, the first magnetic element can include a combination of a permanent ferromagnet and a temperature-sensitive magnetic element. In this case, the temperature-sensitive magnetic element can be disposed above the permanent ferromagnet in the first arm. The temperature-sensitive magnetic element can be between the hair contact surface and the permanent ferromagnet. In a plan view from the hair contact surface, the diameter of the temperature-sensitive magnetic element can be greater than or equal to the diameter of the permanent ferromagnet. Thus, in the closed configuration, the temperature-sensitive magnetic element can be between the permanent ferromagnet and the second magnetic element. This enables the temperature-sensitive magnetic element to control the attraction between the permanent ferromagnet and the second magnetic element. When the temperature of the temperature-sensitive magnetic element is below the Curie temperature, the temperature-sensitive magnetic element is ferromagnetic, and thus there is a relatively high attraction between the first magnetic element and the second magnetic element. When the temperature of the temperature-sensitive magnetic element is above the Curie temperature, the temperature-sensitive magnetic element is paramagnetic, and thus the attraction between the first magnetic element and the second magnetic element is relatively low.

[0040] In an alternative embodiment, the second magnetic element may comprise a temperature-sensitive magnetic element. Thus, when the appliance is in the closed configuration, as long as the temperature of the second magnetic element is below its Curie temperature, the permanent ferromagnet (first magnetic element) and the soft ferromagnetic material (second magnetic element) will be magnetically attracted to each other. At the time of writing, we consider this alternative embodiment to be less preferred than the device further indicated above, in the arrangement further indicated above, the first magnetic element comprises a combination of a permanent ferromagnet and a temperature-sensitive magnetic element. For example, when the permanent ferromagnet is covered by the temperature-sensitive magnetic element, when the temperature of the temperature-sensitive magnetic element is above the Curie temperature, the device emits only a smaller magnetic field, so that unwanted items such as hairpins or clips are less likely to be attracted to the device.

[0041] The temperature-sensitive magnetic latching device may be arranged closer to the free ends of the first and second arms than the biasing device. This means that the temperature-sensitive magnetic latching device can benefit from a mechanical lever effect in order to counteract the biasing device's push on the arms towards the open configuration in the closed configuration.

[0042] The appliance may have a central pack disposed between the first and second arms. The biasing device may be adapted to symmetrically support the central pack between the first and second arms. The central pack may house a power source such as a rechargeable battery. In some embodiments, the pack may form part of one of the arms. In this case, the appliance may not be symmetric, as there is a first arm on one side, which can pivot relative to the combination of the second arm and the associated body (or pack), which contains, for example, the power source and / or control electronics.

[0043] The present invention includes combinations of aspects and optional features, unless such combinations are clearly not permitted or are explicitly avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Embodiments and experiments illustrating the principles of the present invention will now be discussed with reference to the accompanying drawings, in which:

[0045] Figure 1 is a side view of a hair styling appliance according to the prior art, with the arms in the closed position.

[0046] Figure 2 is a side view of the hair styling appliance shown in Figure 1, with the arms in the open position.

[0047] Figure 3 shows a first configuration of a spring mechanism between the arms, suitable for use with the appliance of Figure 1.

[0048] Figure 4 shows an alternative configuration of the spring mechanism between the arms, suitable for use with the appliance of Figure 3.

[0049] Figure 5 A side view of a hair styling appliance according to an embodiment of the present invention is shown, with the arms in the closed position.

[0050] Figure 6 shows a Figure 5 side view of a hair styling appliance with the arms in the open position. DETAILED DESCRIPTION

[0051] Aspects and embodiments of the present invention are discussed further below with reference to the accompanying drawings. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned herein are incorporated herein by reference.

[0052] Embodiments of the present invention are described with reference to the disclosure of WO2020 / 141295A1, which presents a hair styling appliance, and in some aspects, embodiments of the present invention can be considered a modification of the disclosure of WO2020 / 141295A1.

[0053] As shown in FIGS. 1 and 2, a hair styling device 10 according to the prior art includes a first arm 12, a second arm 14, and a central group 16, which are pivotally connected together at one end by a hinge 18. The hair styling device 10 includes a handle section 20 towards the hinge end of the arms and a hair contact section 22 towards the distal ends of the arms. The hair contact section 22 includes plates 24, 26 provided on at least one facing surface of the arms. The plates 24, 26 can be flexible or non-flexible hair contact plates, which will increase in temperature when the straightening device 10 is in use. When the straightening device 10 is not in use, the plates are typically at ambient temperature.

[0054] A longitudinal axis x is marked in FIGS. 1 and 2, which extends longitudinally through the center of the hair styling appliance 10.

[0055] The hair styling appliance 10 is typically a battery-powered straightener, where the hair contact section 22 includes a heated metal plate. In such an embodiment, an electrical connector 28 is located at the hinge end of the hair styling device 10, and the central group 16 is a battery pack assembly.

[0056] The hair styling device of WO2020 / 141295A1 includes a biasing device (not shown in FIGS. 1 and 2), which is in the form of one or more springs and is adapted to support the central group 16 between the first arm and the second arm. This symmetric, balanced arrangement improves the ergonomics of the hair care device. A suitable biasing device will be described below with reference to FIGS. 3 and 4.

[0057] FIGS. 3 and 4 schematically show options for elastically fixing the arms and the central group together such that the arms can be biased to the open position and also smoothly closed by the user.

[0058] FIG. 3 shows a first helical spring 162 attached between the inner surface of the first arm 12 and the adjacent surface of the central group 16, and a second helical spring 164 attached between the inner surface of the second arm 14 and the central group 16. This symmetric arrangement is mechanically simple and reliable while maintaining a balanced distribution of weight within the shaping device. Alternatively or additionally, third and fourth helical springs 166, 168 may be positioned closer to the hinge end 18 of the shaping device 10. FIG. 3 also shows an alternative arrangement of such helical springs.

[0059] FIG. 4 schematically shows a first leaf spring 170 located between the inner surface of the first arm 12 and the adjacent surface of the central group 16, and a second leaf spring 172 located between the inner surface of the second arm 14 and the central group 16. The first leaf spring and the second leaf spring 170, 172 are made of metal, and the cross-section may be flat or cylindrical, and each of the first leaf spring and the second leaf spring may be composed of one or more leaf springs. Similarly, this symmetric arrangement is mechanically simple and reliable while maintaining a balanced weight distribution within the shaping device. In one arrangement, the first arm and the second arm include metal arm structures 174, 176, and the leaf springs 170, 172 are integrally formed with the metal arm structures. This metal arm structure contributes to the rigidity of the device, and the outermost surface of the metal arm structure is covered with a plastic layer.

[0060] Now turning to the discussion of embodiments of the present invention, Figure 5 FIG. 8 shows a side view of a hair styling appliance 200 according to an embodiment of the present invention, where the arms are in the closed position. Figure 6 Shows Figure 5 a side view of the hair styling appliance, but the arms are in the open position.

[0061] As Figure 5 and Figure 6 shown, the hair styling appliance 200 includes a first arm 212 and a second arm 214. Each arm has a free end 212a, 214a and a hinge end 212b, 214b, and the arms are coupled together by a hinge 218 located at their respective hinge ends to allow the first arm 212 and the second arm 214 to move between a closed position ( Figure 5 ) and an open position ( Figure 6 ).

[0062] The hair styling appliance 200 further includes a biasing device configured to bias the first arm and the second arm towards the open position. In Figure 5 and Figure 6 , the biasing device is schematically shown as a spring 213, but it should be understood that the biasing device may have the form shown in FIG. 3 or FIG. 4.

[0063] As Figure 6As shown, the central group 216 is symmetrically disposed between the first arm 212 and the second arm 214.

[0064] The first arm 212 is provided with a flexible hair contact plate 224 which is located above and in thermal contact with the first heater 225. Similarly, the second arm 214 is provided with a flexible hair contact plate 226 which is located above and in thermal contact with the second heater 227. The flexible hair contact plates provide hair contact surfaces that face each other near the free ends of the first and second arms.

[0065] The hair styling appliance 200 further includes a temperature-sensitive magnetic latch device 250. This is configured to hold the first and second arms in the closed position when at least a portion of the magnetic latch is below a first threshold temperature. This is further configured to release the first and second arms from the closed position when at least a portion of the magnetic latch is above the first threshold temperature to allow the biasing device to move the first and second arms to the open position.

[0066] The temperature-sensitive magnetic latch device 250 includes first magnetic elements 252, 254 on the first arm 212 and second magnetic elements 256 on the second arm. The first magnetic elements include a permanent ferromagnetic body 252 (such as a neodymium-based permanent ferromagnetic body), and the second magnetic elements may include a soft ferromagnetic material (such as low-carbon steel).

[0067] The first magnetic elements further include a temperature-sensitive magnetic element 254. The temperature-sensitive magnetic element 254 is disposed above the permanent ferromagnetic body 252 in the first arm 212, below and in thermal contact with the flexible hair contact plate 224. As Figure 6 shown, the temperature-sensitive magnetic element 254 is interposed between the flexible hair contact plate 224 and the permanent ferromagnetic body 252.

[0068] Viewed from a plan view of the hair contact surface, the diameter of the temperature-sensitive magnetic element 254 is greater than the diameter of the permanent ferromagnetic body 252. As Figure 5 shown, in the closed configuration, the temperature-sensitive magnetic element 254 is interposed between the permanent ferromagnetic body 252 and the second magnetic element 256. This enables the temperature-sensitive magnetic element 254 to control the attraction between the permanent ferromagnetic body 252 and the second magnetic element 256.

[0069] When the temperature of the temperature-sensitive magnetic element 254 is below the Curie temperature (such as 100 °C), the temperature-sensitive magnetic element 254 has ferromagnetism, so there is a relatively high attraction between the first magnetic elements and between the second magnetic elements. When the temperature of the temperature-sensitive magnetic element is above the Curie temperature, the temperature-sensitive magnetic element 254 is paramagnetic, so the attraction between the first magnetic element and the second magnetic element is relatively low.

[0070] The temperature-sensitive magnetic latch device can be arranged closer to the free ends of the first and second arms than the biasing device. This means that the temperature-sensitive magnetic latch device can benefit from a mechanical lever effect to counteract the push of the biasing device on the arms towards the open configuration in the closed configuration.

[0071] The biasing device 213 can exhibit a spring force of approximately 3 N, which means that a force of approximately 3 N is sufficient to compress the spring. Thus, considering the mechanical lever effect provided by the arms 212, 214, this indicates the attractive force required to hold the appliance in the closed configuration between the first and second magnetic elements below the threshold temperature.

[0072] In use, the user powers on the appliance and heats the heater from ambient temperature to the operating temperature. When the temperature of the temperature-sensitive magnetic element 254 is below the threshold temperature, the magnetic latch device holds the first and second arms in the closed position. When the temperature of the temperature-sensitive magnetic element 254 is above the threshold temperature, the temperature-sensitive magnetic element 254 changes from ferromagnetic to paramagnetic. This has the effect of reducing the attractive force between the first and second magnetic elements, such that the biasing device can overcome the attractive force between the first and second magnetic elements and the biasing device moves the first and second arms to the open position. This indicates to the user that the device is heating up and is ready for use. Another advantage of this arrangement is that the appliance will heat up faster when in the closed configuration.

[0073] After styling the hair using the appliance, the user turns off the appliance, but for at least some time, the temperature of the temperature-sensitive magnetic element 254 will remain above the threshold temperature. In this case, even if the user closes the arms, the magnetic latch cannot hold the first and second arms in the closed position. When the appliance cools to ambient temperature, the temperature of the temperature-sensitive magnetic element will approach and drop below the Curie temperature. When the user closes the arms, the magnetic latch will hold the first and second arms in the closed position, indicating that the appliance is ready for storage.

[0074] Another advantage of using the magnetic latch device described herein is that it can resist damage when the arms are forced open. For a mechanical latch device, forcing the arms open may damage, weaken, or loosen the mechanical latch, and it may not be easily repairable. However, in the case of a magnetic latch device, unless the arms are opened with a force sufficient to overcome the attractive force between the first and second magnetic elements, the arms will remain closed. In this case, the first and second magnetic elements generally do not get damaged or weakened, and they are able to hold the arms in the closed position again when the arms are recombined.

[0075] The features disclosed in the foregoing description, the appended claims or the drawings, in their specific forms or in the form of means for performing the disclosed functions or of a method or process for obtaining the disclosed results, may be used alone or in any combination of these features to implement different forms of inventions.

[0076] Although the present invention has been described in connection with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art when the present disclosure is given. Therefore, the above exemplary embodiments of the present invention are considered to be illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the present invention.

[0077] To avoid any doubt, any theoretical explanations provided herein are for enhancing the reader's understanding. The inventors do not wish to be bound by any theoretical explanations.

[0078] Any chapter headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0079] Throughout the specification (including the following claims), unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprises", "includes" and "including" shall be understood to mean including the stated integer or step or group of integers or steps but not excluding any other integer or step or group of integers or steps.

[0080] It must be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from one particular value and / or to another particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment. The term "about" associated with a numerical value is optional and, for example, means + / - 10%.

Claims

1. A hair styling appliance, comprising: A first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end, and being joined together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position; A biasing device configured to bias the first arm and the second arm towards the open position; A hair contact surface provided at the free ends of the first arm and the second arm, the hair contact surfaces facing each other, and at least one of the hair contact surfaces being provided with a heater; And A temperature-sensitive magnetic latching device configured to hold the first arm and the second arm in the closed position when the temperature of at least a portion of the magnetic latch is below a first threshold temperature, and to release the first arm and the second arm from the closed position when the temperature of at least a portion of the magnetic latch is above the first threshold temperature, to allow the biasing device to move the first arm and the second arm to the open position.

2. The hair styling device according to claim 1, wherein the temperature-sensitive magnetic latching device is arranged in thermal contact with the heater.

3. The hair styling device according to claim 1 or 2, wherein the temperature-sensitive magnetic latching device comprises a temperature-sensitive magnetic element having a Curie temperature such that: (i) when the temperature of the temperature-sensitive magnetic element is below the first threshold temperature, the temperature-sensitive magnetic element is ferromagnetic, and (ii) when the temperature of the temperature-sensitive magnetic element is above the first threshold temperature, the temperature-sensitive magnetic element is non-ferromagnetic.

4. The hair styling device according to claim 3, wherein when the temperature of the temperature-sensitive magnetic element is above the first threshold temperature, the temperature-sensitive magnetic element is paramagnetic.

5. The hair styling device according to any one of claims 1 to 4, wherein the Curie temperature of the temperature-sensitive magnetic element is in the range of 50 - 150 °C.

6. The hair styling device according to any one of claims 1 to 5, wherein the temperature-sensitive magnetic latching device comprises a first magnetic element on the first arm and a second magnetic element on the second arm, wherein the first magnetic element comprises a permanent ferromagnet, and the second magnetic element comprises a soft ferromagnetic material.

7. The hair styling device according to claim 6, wherein the second magnetic element comprises a temperature-sensitive magnetic element.

8. The hair styling device according to claim 6, wherein the first magnetic element comprises a combination of a permanent ferromagnet and a temperature-sensitive magnetic element.

9. The hair styling device according to claim 8, wherein the temperature-sensitive magnetic element is provided above the permanent ferromagnet in the first arm.

10. The hair styling device according to claim 8 or 9, wherein the temperature-sensitive magnetic element is between the hair contact surface and the permanent ferromagnet.

11. The hair styling device according to any one of claims 8 to 10, wherein, Viewed from a plan view of the hair contact surface, the diameter of the temperature-sensitive magnetic element is greater than or equal to the diameter of the permanent ferromagnet.

12. The hair styling device according to any one of claims 1 to 11, wherein the temperature-sensitive magnetic latch device is arranged closer to the free ends of the first and second arms than the biasing device.

13. The hair styling device according to any one of claims 1 to 12, wherein the appliance has a central group arranged between the first and second arms, and the biasing device is adapted to symmetrically support the central group between the first and second arms.

14. A method of operating a hair styling appliance, the hair styling appliance comprising: A first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end, and being joined together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position; A biasing device configured to bias the first and second arms towards the open position; A hair contact surface provided at the free ends of the first and second arms, the hair contact surfaces facing each other, at least one of the hair contact surfaces being provided with a heater; and A temperature-sensitive magnetic latch device, wherein the method comprises the steps of: Switching on the power supply to heat the heater, wherein the magnetic latch device holds the first and second arms in the closed position while the temperature of at least a portion of the magnetic latch is below a first threshold temperature; And When at least a portion of the magnetic latch is above the first threshold temperature, the magnetic latch releases the first and second arms from the closed position, and the biasing device moves the first and second arms to the open position, thereby indicating that the appliance is heating up in preparation for use.

15. A method of operating a hair styling appliance, the hair styling appliance comprising: A first arm and a second arm, each of the first arm and the second arm having a free end and a hinge end, and being joined together at their respective hinge ends to allow the first arm and the second arm to move between a closed position and an open position; A biasing device configured to bias the first and second arms towards the open position; A hair contact surface is provided at the free ends of the first and second arms, the hair contact surfaces face each other, at least one of the hair contact surfaces being provided with a heater; and A temperature-sensitive magnetic latch device, wherein the method comprises the steps of: The user uses the hot plate to style the hair; When the temperature of at least a portion of the magnetic latch is above the first threshold temperature, the magnetic latch cannot overcome the pushing force of the biasing device to hold the first and second arms in the closed position, and the power supply to the heater is cut off, thereby allowing the hot plate to cool, so that at least a portion of the magnetic latch cools below the first threshold temperature; And The user overcomes the pushing force of the biasing device to close the first and second arms to the closed position and the magnetic latch holds the first and second arms in the closed position, thereby indicating that the appliance is ready for storage.

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