GB2465865A

GB2465865A - Hair iron

Info

Publication number: GB2465865A
Application number: GB0917036A
Authority: GB
Inventors: Hae Jin Kim
Original assignee: GHD Korea Inc
Current assignee: GHD Korea Inc
Priority date: 2008-01-09
Filing date: 2009-09-29
Publication date: 2010-06-09
Anticipated expiration: 2029-09-29
Also published as: GB0917036D0; AU2009230805A1; GB2465865B

Abstract

A hair iron to heat hair of a user comprises a heating part 102a,102b, a heater 235 and a heating plate 231. The heating plate is made of magnesium or a magnesium alloy which is treated by anodizing. Preferably, the content of magnesium is 90% or more, and the content of aluminum ranges from 1.5% to 9.5%. The surface of the heater which is in contact with the heating plate is coated with a double electrical insulation film 2351, 2352 to prevent electrical shocks. In use, the thickness and weight of the heating plate can be reduced compared to conventional devices whilst maintaining the mechanical strength and the heat transfer efficiency at the required levels.

Description

HAIR IRON

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hair iron.

2. Description of the Related Art

Generally, hair irons are apparatuses which apply heat to hair to style the hair. Hair irons are widely used to shape desired hairstyles in beauty salons or homes.

Typically, such a hair iron includes two bodies between which is placed some hair. A heating unit is provided in at least one body to apply heat to the hair. Furthermore, with respect to the longitudinal direction, the hair iron includes a heating part which has the heating unit therein, and a handle part which is held by a user's hand. The heating unit includes a heating plate which is brought into direct contact with the hair, and a heat generator, such as a heater, which generates heat and supplies the heat to the heating plate.

When power is applied to the heat generator, the heating plate is heated by heat transferred from the heat generator thereto. Then, the shape of the hair which has been placed between the heating plates of the upper and lower bodies varies because of the heat and pressure. As such, in terms of the intended purposes of the hair iron, the heating plates are the most critical parts of the hair iron, as these directly affect the performance of the hair iron and the hair styling operation.

In a heating unit of a conventional hair iron, each heating plate is made of ceramic or metal. In the case where the heating plate is made of metal, a ceramic coating is typically applied to the surface of the heating plate.

Furthermore, steel or aluminum is generally used as the metal for the heating plate. However, in the case of the steel heating plate made of steel or stainless steel, it increases the entire weight of the hair iron, thus inconveniencing the user.

Aluminum is not stronger than steel, but the specific gravity of aluminum is lower than that of steel so that an aluminum product is advantageous because light. Furthermore, if the aluminum product is anodized to form a stable oxide film, the durability thereof can be enhanced. Due to these advantages, aluminum products have been very widely used.

However, recently, the product-related requirements of consumers have diversified. In particular, requirements for lightness, thinness, shortness and smallness of the products are increasing. In response to this, development of hair irons which are lighter and thinner than the conventional hair iron having the aluminum heating plates is required.

Moreover, according to an increasing demand for portability of electric devices, hair irons are also required to be portable.

Basically, such a portable product must be light and small.

Particularly, in the case of a product having a charging battery as a power supply, to make the product smaller and lighter in consideration of the battery, the weight and size of other elements must be further reduced.

Meanwhile, the heater is in contact with the heating plate to apply heat thereto. Here, because the heater generates heat using electricity supplied from the power supply, if some problem occurs in the heater and electric current flowing through the heater are thus applied to the heating plate, there is a risk of inflicting the user with an electric shock. It has been thought that such an accident is attributable to an electric leakage or an electric shock can be prevented by coating the heating plate with an electrical insulation material or by insulating the heating plate through an anodizing process.

However, recently, to enhance the safety of electric products, according to requirements for improvement in insulation of the heating plate with respect to electricity supplied from the power supply, a method of reliably preventing an electric shock from occurring through the metal heating plate that may be easily brought into contact with the human body is required.

The conventional method in which the heating plate is electrically insulated is the simplest method for improvement of insulation performance. However, this method is problematic in that because the heating plate is exposed to the outside, the insulation film may be damaged afterwards.

In addition, since the shape of the heating plate is complex, it is difficult to insulate the heating plate using a simple taping method. Thus, a coating method must be used, but this increases the production cost and is therefore burdensome.

As another method for improvement of insulation performance, there is a method of improving insulation performance of the heater. In this method, an insulation material, such as a Teflon coating, is applied between the metal heating plate and the heater. However, in the case of products using such an insulation material, there is a disadvantage in that the thickness of the heating plate increases due to the thickness of the insulation material.

Furthermore, the heat transfer efficiency is reduced, that is, heat loss is increased, compared to that of the structure in which heat is directly transferred from the heater to the heating plate. For instance, in the case of the prior product in which the heater is in direct contact with the heating plate so that heat is directly transferred from the heater to the heating plate, it takes between 45 and 60 seconds to increase the surface temperature of the heating plate to the temperature of 180°C at which it is normally used. However, in the case where an insulation material, such as a Teflon coating, of 40 pm to 50 pm is applied between the heater and the heating plate to improve the insulation performance of the product having the same specifications, the temperature of the heating plate is reduced to 175 °C, and the time required to increase the heating plate to this temperature becomes 120 seconds, in other words, becomes doubled. Thus, the time that has to be spent waiting before using is increased.

Therefore, a method of compensating for reduced performance relative to an increase in temperature is required. That is, a method is required, which can satisfy the requirements in which the normal use temperature (ranging from 185 °C to 190 °C) of the heating plate must be increased despite having a safe electrical insulation structure and the time required to increase the temperature of the heating plate to the increased use temperature must be similar to that of the prior technique or be reduced (to 30 seconds), thus reducing the time spent waiting prior to using.

As one method to achieve the above purposes, the thickness of the heating plate may be reduced to about 1mm.

However, the heating plate may be undesirably bent or deformed if the heating plate is thinner than the prior heating plate and is made of aluminum which cannot resist deformation in the heated state. In other words, when an aluminum heating plate is heated, the mechanical strength thereof is reduced. Thus, if the aluminum heating plate is formed thin to meet requirements in the design of the hair iron, it may be easily deformed by external force or impact.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a hair iron which includes a heating plate which is configured such that the weight and thickness thereof can be reduced compared to those of the conventional aluminum heating plate, without deteriorating the convenience of use or mechanical strength, thus enhancing the degree of freedom in design of the hair iron.

Another object of the present invention is to provide a hair iron in which heat is rapidly transferred from a heater to the heating plate despite using a double electrical insulation method to prevent an electric shock, thereby reducing the waiting time prior to use.

A further object of the present invention is to provide a hair iron which includes the heating plate which can be easily varied in design in consideration of weight and size, thereby affording a portable product.

In order to accomplish the above object, the present invention provides a hair iron including a heating part to heat hair of a user. The heating part includes a heater and a heating plate. The heating plate which is brought into direct contact with the hair is made of magnesium or a magnesium alloy and is treated by anodizing. In the magnesium alloy, the content of magnesium can be 90% or more, and the content of aluminum ranges from 1.5% to 9.5% and, more preferably, from 2% to 8.5%.

In the present invention, a portion of the anodized surface of the heating plate, in particular, a portion which is in direct contact with the heater, may be coated with a heat resistant synthetic resin, such as Teflon.

Furthermore, the heater which transfers heat to the heating plate may be coated with a double electrical insulation film. Here, a polyimide sheet having superior heat conductivity may be used as the double electrical insulation film. Preferably, an adhesive tape type polyimide film may be used.

In addition, the heating plate may have a thickness ranging from 0.8mm to 1.2mm, more preferably, from 0.8mm to 1mm. As such, the present invention is characterized in that the heating plate is relatively thin. However, if the heating plate is too thin, for example, is of a thickness less than 0.8mm, the mechanical strength may not be maintained, although the heating plate is made of magnesium.

Preferably, a ceramic coating is applied to at least the portion of the anodized surface of the heating plate which is brought into contact with the hair.

Furthermore, the hair iron of the present invention may have a portable structure including a charging battery. In this case, the characteristics of the heating plate of the present invention can be more suitably adapted thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is an exploded perspective view illustrating a hair iron, according to a first embodiment of the present invention; FIG. 2 is an exploded perspective view of a heater block of the hair iron of FIG. 1; FIG. 3 is a lateral sectional view of the assembled heater block of FIG. 2 from which a holder is removed; FIG. 4 is an exploded perspective view of a heater block of a hair iron, according to a second embodiment of the present invention; FIG. 5 is a perspective view of the assembled heater block of FIG. 4 from which a holder is removed; FIG. 6 is a lateral sectional view of the assembled heater block of FIG. 5; FIG. 7 is a lateral sectional view of a heater block of a hair iron from which a holder is removed, according to a third embodiment of the present invention; and FIG. 8 is an exploded perspective view illustrating a rechargeable hair iron, according to a fourth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is an exploded perspective view illustrating a hair iron, according to a first embodiment of the present invention. The hair iron includes upper and lower casings lOla and lOib which serve as the framework of the hair iron.

Heater blocks lO2a and lO2b and inner covers 103a and 103b are fastened to and arranged in lines on inner surfaces (facing each other) of the upper and lower casings lOla and lOlb.

First ends of the upper and lower casings lOla and lOib form a structure capable of rotating the upper and lower casings lOla and lOib around a rotating shaft 106 within a predetermined angular range using a means, such as a hinge. With respect to the longitudinal direction of the hair iron, portions to which the heater blocks are mounted form a heating part or a heater installation part, and portions to which the inner covers are disposed form a handle.

With regard to the junction at which the upper and lower casings lOla and lOib are coupled to each other so as to be rotatable within a predetermined angular range, a seating part lila and a support plate 104a which has a through hole lOSa at the central portion thereof are provided on the first end of the upper casing lOla at positions spaced apart from each other by a predetermined distance. The seating part lila and the support plate 104a are parallel to each other. In addition, a seating part ilib and a support plate 104b which has a through hole 105b at the central portion thereof are provided on the first end of the lower casing iOlb at positions spaced apart from each other by a predetermined distance. The seating part lllb and the support plate 104b are parallel to each other and respectively correspond to the support plate lO4a and the seating part lila.

A spring 107 into which a bushing 110 is inserted is disposed between one of the support plates 104a and lO4b and the corresponding seating part lila, lllb. Thereafter, the upper casing lOla and the lower casing lOib are coupled to each other. The rotating shaft 106 is inserted into the bushing 110 through the through hole 105a or 105b.

Subsequently, screws 109 are tightened into both ends of the rotating shaft 106. Due to this structure, the upper and lower casings lOla and lOib can be rotated around the rotating shaft 106 to a predetermined angle by external force applied to the upper and lower casings lOla and lOib or the elastic force of the spring 107.

Referring to FIGS. 2 and 3, each heater block 102a, 102b which is a heat generating structure includes a heating plate 231, a heater 235, a silicone grease layer 233, an adiabatic plate (not shown) and a holder 220. The heating plate 231 is exposed outside and is brought into direct contact with the hair of a user. The heater 235 is installed on the inner surface (adjacent to the corresponding casing) of the heating plate 231 and generates heat to be applied to the heating plate 231. The silicone grease layer 233 is interposed between the heater 235 and the heating plate 231 to evenly transfer heat from the heater 235 to the heating plate 231.

The adiabatic plate is made of material such as mica to prevent heat of the heater 235 from being transferred to the casing lOla, bib. The holder 220 holds the heating plate 231 to dispose it in the casing lOla, bib. A hole or depression is formed in a portion of a body of the holder 220 which has a convex shape. A fuse fastening spring 240 which holds a heater fuse 265 is installed in the holder 220 through the hole or depression.

The heating plate 231 is made of magnesium or a magnesium alloy which has a low specific gravity and superior mechanical strength, compared to aluminum which has been used as the heating plate in the conventional technique. Here, magnesium alloy is used more than magnesium because of superior processibility. A magnesium alloy, such as Dow metal, including magnesium of 90% or more and aluminum of 1.5% to 9.5% (more preferably, 2% to 8.5%) is mainly used. Such an alloy may include a very small amount of elements, such as manganese, zinc, silicon, etc. If aluminum content is not within the above-mentioned range, for example, if it is too small, the effect of the alloy which enhances the processibility in molding or forging and improves corrosion prevention ability may not be sufficient. If aluminum content is beyond the above range, the characteristics of magnesium are reduced, with the result that the hardness markedly decreases.

The specific gravity of magnesium is two-thirds that of aluminum and it is the lightest of commercial metals.

Furthermore, magnesium can maintain its strength at room temperature and within the range of from 100°C to 200°C at which the hair iron is used. In addition, magnesium has superior resistance against deformation, such as bending, compared to aluminum. Thus, under conditions of the same strength and deformation resistance, magnesium can reduce the thickness of the heating plate by 30%.

As such, in the case where the thickness of the heating plate is reduced by using magnesium as the material therefore, the weight thereof can be reduced to half of the conventional aluminum heating plate. As well, the length of a path along which heat is transferred from the heater to the hair is reduced, so that resistance of heat transfer is reduced.

Hence, although the heat conductivity of magnesium is slightly less than that of aluminum, the whole resistance of heat transfer of the heating plate made of magnesium can be lower than that of the heating plate made of aluminum. Moreover, the design of the hair iron can assume a variety of shapes because of a reduction in thickness. Therefore, generally, the magnesium heating plate 231 makes it possible to produce a light, thin, short and small hair iron. The magnesium heating plate 231 can be formed by molding, hot forging, die casting or the like. Particularly, in the case of the magnesium alloy, despite maintaining the advantages of magnesium, the processibility, the ductility and the malleability can be enhanced, compared to magnesium. Meanwhile, to prevent surface corrosion, an oxide film 231a of 20 to 30 micrometers may be formed on the front surface of the heating plate 231 by anodizing. Hereby, the heating plate 231 can be prevented from being corroded by acids or bases or being damaged by scratching. Although it is well known that the oxide film 231a of magnesium cannot withstand high temperature, the oxide film is sufficiently stable at the temperature of about 200°C at which the hair iron is used. Furthermore, in the case where the oxide film 231a of magnesium is previously formed by anodizing, the ability of adhering a ceramic coating 231b to the surface of the heating plate 231 can be increased, compared to a conventional aluminum oxide film. Therefore, the workability in applying the ceramic coating 231b to the heating plate 231 can be enhanced. The surface strength of the ceramic coating 231b formed on the heating plate 231 can be increased. The ceramic coating 231b also functions to prevent the magnesium heating plate 231 from oxidizing.

Furthermore, the ceramic coating 231b can more reliably prevent the hair from being damaged when it comes into contact with the hair, compared to when the hair is brought into direct contact with metal or the oxide film formed by anodizing. In addition, the ceramic coating 231b enables the hair to smoothly slide relative to the surface of the heating plate 231.

In this embodiment, a Teflon coating 231c is applied to the concave inner surface of the heating plate 231 to which the heater 235 is attached. The ceramic coating 231b having a thickness of several tens of micrometers is applied to the outer surface of the heating plate 231 which is brought into direct contact with the hair of the user. The ceramic coating is a well known technique which has been applied to the metal heating plate such as the conventional aluminum heating plate, therefore the explanation of the detailed coating method will be omitted. A fluorine resin or other kind of synthetic resin coating which has high heat resistance and superior insulation ability substitutes for the Teflon coating 231c which is applied to the heating plate 231. In the drawings, the reference numeral 237 denotes a mica layer.

The synthetic resin coating which is applied to the inner surface of the heating plate 231 and the oxide film which is applied to the entire surface of the heating plate 231 can prevent electric current from leaking through the heating plate 231 made of magnesium or magnesium alloy, that is, they form a double electric leakage prevention structure.

Furthermore, the synthetic resin coating, along with the inner oxide film, can also function to prevent the magnesium heating plate from being contaminated or deformed, thus enhancing the durability of the magnesium heating plate. The synthetic resin coating may be applied to the heating plate, for example, with a thickness of about 10 to 100 micrometers. If the synthetic resin coating is excessively thick, resistance to heat transfer between the heater 235 and the heating plate 231 is increased. If the synthetic resin coating is excessively thin, it may be easily damaged and cannot function as an electrical insulation film or a protective film.

FIG. 4 is an exploded perspective view of a heater block of a hair iron, according to a second embodiment of the present invention. FIG. 5 is a perspective view of the assembled heater block of FIG. 4 from which a holder 220 is removed. FIG. 6 is a lateral sectional view of the assembled heater block of FIG. 5.

Referring to FIGS. 4 through 6, the heater block which is a heat generating structure includes a heating plate 231, a heater 235, a fuse 265, a fuse fastening spring 240 which closely assembles the fuse 265, the heater 235 and the heating plate 231, and a holder 220 which holds the heating plate 231 to dispose it in a casing of the hair iron. The general construction of the heater block according to the second embodiment is similar to that of the heater block of the first embodiment.

However, unlike the heater block of the first embodiment, the heater 235 is coated with two layered electrical insulation films 2351 and 2353. The detailed structure of the fuse fastening spring 240 differs from that of the first embodiment. The insulation films 2351 and 2353 are made of material having superior heat conductivity, thermal resistance and superior electrical insulation ability. Preferably, a polyimide-based (P1-based) resin which is called a Kapton� tape or Kapton� film can be used as the material of the insulation films 2351 and 2353. Polyimide resin can be used at a high temperature of 300°C or more and can be easily formed in a shape of a film having a thickness of 0.01mm to D.lrruTI. The polyimide resin film may be adhered to an object only by pressure or, alternatively, it may be formed in a tape shape which is coated with polyimide-based adhesive and then adhered to the heater 235. The double structure of the insulation film denotes the structure in which the insulation film applied to the surface of the heater 235 comprises a plurality of layers. As such, in the case where the insulation film has the double structure, even if one layer of the insulation film is damaged, the defect does not affect the other layer. Therefore, the insulation film having double thin layers can further enhance the reliability and safety of electrical insulation, compared to the insulation film having one single thick layer.

In the double structure of the insulation film, the heater 235 is coated with a first insulation layer and the heater 235 which has been coated with the first insulation layer is coated with a second insulation layer, such that an overlapped portion of the first insulation layer, if any, and/or an overlapped portion of the second insulation layer, if any, is prevented from being disposed on the surface of the heater 235 which faces the heating plate 231. Furthermore, the overlapped portion of the first insulation layer and the overlapped portion of the second insulation layer must not overlap each other. The reason for this is that the distance between the heater 235 and the heating plate 231 may be undesirably increased by the overlapped portions with the result that the heat transfer efficiency from the heater 235 to the heating plate 231 is reduced.

The fuse 265 is configured such that when heat generated from the heater 235 exceeds the maximum use temperature of the hair iron, for example, 19000 to 200°C, an internal wire is burned out to cut off electric current supplied to the heater 235 that is electrically connected to the fuse 265. In this embodiment, because electric wires are connected to the fuse 265, it is also double-insulated with an insulation coating or an insulation film.

The fuse fastening spring 240 is made of an elastic steel plate. The fuse fastening spring 240 includes a rectangular rim-shaped frame 247, heater pressing pieces 241, fastening pieces 245 and a fuse pushing piece 245. The heater pressing pieces 241 extend outwards from the edges of both longitudinal ends of the rectangular rim-shaped frame 247 and are bent towards the heating plate 231 to press the heater 235 such that the heater 235 is brought into close contact with the heating plate 231. The fastening pieces 245 extend outwards from side edges of the rectangular rim-shaped frame 247 in the lateral direction and are coupled to locking protrusions 2313 which are provided on the lower surface of the heating plate 231. The fuse pushing piece 243 protrudes inwards from the rectangular rim--shaped frame 247 and is double bent such that the fuse 265 which is in contact with the surface of the heater 235 opposite the heating plate 231 is pushed towards the heater 235 by the fuse pushing piece 243.

In this embodiment, an adiabatic plate made of mica or the like may be further used, although it is not shown in the drawings. Meanwhile, because the heater 235 and the heating plate 231 have solid phases, when these come into contact with each other, only protruding portions formed on the surfaces thereof substantially come into contact with each other in a point contact manner, so that the heat transfer efficiency may be reduced. The silicone grease layer 233 is meant to solve the above problem. In this embodiment, a polyimide film is interposed between the heater 235 and the heating plate 231.

In addition, the fuse fastening spring 240 presses the heater 235 to the heating plate 231 such that the heater 235 is sufficiently brought into close contact with the heating plate 231. Hence, the necessity of the silicone grease layer is reduced, so that it is omitted in this embodiment.

In the heater block of this embodiment, the heater 235 which is in close contact with the heating plate 231 is doubly insulated with the two insulation films 2351 and 2352.

Therefore, although the heating plate 231 has no separate insulation means, exposing electric current to the outside through the heating plate 231 can be prevented. Thus, in this embodiment, it is not required to apply an insulation means, such as a Teflon coating, to the heating plate 231. For example, the heating plate 231 having metal gloss may be directly used, or the heating plate 231 may be coated only with ceramic.

FIG. 7 is a lateral sectional view of a heater block of a hair iron from which a holder is removed, according to a third embodiment of the present invention.

In the third embodiment, a heating plate 231 is also made of magnesium or a magnesium alloy. Therefore, the heating plate 231 of the third embodiment can also have advantages which can be obtained when magnesium or a magnesium alloy is used as the material of the heating plate 231. The general construction of the third embodiment is similar to that of the second embodiment of FIG. 6.

The magnesium heating plate 231 according to the third embodiment can be formed by molding, hot forging, die casting or the like. Particularly, in the case where the heating plate 231 is made of magnesium alloy, despite maintaining the advantages of magnesium, the processibility, the ductility and the malleability can be enhanced. Furthermore, to prevent surface corrosion, an oxide film 231a of about 20 to 30 micrometers is formed on the entire surface of the heating plate 231 by anodizing. A ceramic coating 231b is applied to the surface of the heating plate 231 which is coated with the oxide film 231a.

Moreover, double electrical insulation films 2351 and 2352 are applied to the heating plate 231, for example, with a thickness of about 10 to 100 micrometers. If the insulation films are excessively thick, resistance to heat transfer is increased. If the insulation films are excessively thin, it may be easily damaged during the manufacturing process or the use of the hair iron and cannot function as an electrical insulation film.

Hereinafter, a portable hair iron according to a fourth embodiment of the present invention will be described with reference to FIG. 8. In terms of external appearance, a handle part of the casing of the portable hair iron according to the fourth embodiment has a thickness greater than that of the hair iron of the prior embodiment, for example, of FIG. 1, having a power supply wire. The reason for the handle part of the casing being relatively thick is that space is required to install a battery to supply electricity to a heater 435 of the hair iron. The casing of the hair iron includes upper and lower casings 410a and 410b which are coupled at first ends thereof by a hinge so as to be rotatable with respect to each other such that the angle between the upper and lower casings 410a and 410b can be varied. Preferably, the battery is installed in the lower casing 410b.

Preferably, a lithium ion rechargeable battery is used as the battery, because the charge amount thereof is relatively large and it can be charged and discharged so that costs related to the use thereof can be reduced. With regard to the kind of the lithium ion rechargeable battery which is used as the power supply of an apparatus, such as a hair iron, which requires much power, it must have a large capacity and be able to generate high output. Furthermore, to enhance the safety of the use, a pouch type lithium polymer battery is preferably used rather than a cylindrical lithium ion battery. To increase the output, several batteries may be connected in parallel with each other. In addition, a battery package in which several batteries are connected in series or in parallel with each other in response to the specifications of the product may be used as the battery for the hair iron.

Typically, the battery package (battery pack) has therein a protection circuit in order to ensure the safety of charging or discharging. The protection circuit is disposed between charging/discharging terminals of the battery package and a load (in detail, a power connection terminal of the circuit board) or an external power (terminals of a charging/discharging apparatus), thus functioning to intercept electric currents when overcharging or overdischarging is caused.

Meanwhile, a heater control circuit is disposed on a line which connects the battery to the heater 435. Typically, a circuit board 480 which is manufactured by mounting electric devices and electronic devices to a PCB is used as the heater control circuit. Preferably, the circuit board 480 is installed in a separate space which is formed by partitioning the internal space of the casing 410b using a rib to electrically and thermally insulate the circuit board 480 from the battery of the battery pack 451.

The circuit board 480 and the battery pack 451 may be connected to each other in such a way that terminals thereof are directly connected to each other without using a separate connection wire or, alternatively, in such a way that the terminals are connected to each other through an auxiliary connection plate. In a similar manner, a connection terminal which is connected to a wire connected to the terminal of the heater 435 may be provided on the circuit board 480. As a further alternative, an auxiliary connection plate having such a connection terminal may be connected to the circuit board 480.

In this embodiment, the battery pack 451 and the circuit board 480 is installed in a battery casing which includes an upper battery casing 453 and a lower battery casing 455 which are coupled to each other. An opening is formed through the bottom of the lower casing 410b. The lower battery casing 455 is disposed in the opening of the lower casing 410b such that the outer surface of the lower battery casing 455 is flush with the outer surface of the lower casing 410b to form a single continuous surface. Furthermore, a rib is provided in the lower battery casing 455 to partition the internal space of the lower battery casing 455 into a space for installation of the battery pack 451 and a space for installation of the circuit board 480. The battery pack 451 can be connected to the external power supply (or the terminals of the charging/discharging apparatus) and the circuit board 480 through auxiliary connection plates 481 and 483 which are provided on the front and rear ends of the battery pack 451.

In the drawing, the reference numerals 485, 487 and 489 denote accessories of the circuit board 480, in detail, respectively denote a circuit on/off switch, a casing locking unit which is operated in conjunction with the circuit on/off switch, and a lighting lamp.

Here, the circuit board 480 is installed such that it is placed in the vertical direction. Hereby, the handle part of the portable hair iron which is relatively thick can be reduced in thickness. Terminals (not shown) are provided on the front and rear ends of the circuit board 480 so that electric wires which are led from the heater 435 are connected to the terminals.

An electric wire (not shown) which extends forwards from the circuit board 480 installed in the handle part of the lower casing 410b is connected to the heating plate 431 which is the heater block installation portion of the lower casing 410b. An electric wire (not shown) which extends rearwards from the circuit board 480 is connected to the heating plate 431 via the hinge which is disposed in the rear end of the hair iron to rotatably couple the upper and lower casings to each other and via the handle part of the upper casing 4lOa.

The hinge includes a bushing 403, a spring 407, a screw shaft 405 and a hinge cap 409. The spring 407 has an arc-shaped medial portion which is fitted over the bushing 403.

Both ends of the spring 407 respectively support the upper and lower casings 410a and 410b. The screw shaft 405 is inserted through the bushing 403 to maintain the entire hinge structure.

The heater block which is a heat generating structure includes the heating plate 431, the heater 435 and a holder 420. The heating plate 431 is made of a magnesium alloy, and the surface thereof is treated by anodizing. A Teflon coating is applied to the inner surface of the heating plate 431, and a ceramic coating is applied to the outer surface thereof.

The heater 435 is installed on the inner surface (adjacent to the corresponding casing) of the heating plate 431 and generates heat to apply heat to the heating plate 431. The holder 420 holds the heating plate 431 to dispose it in the casing. Preferably, a silicone grease layer (not shown) is interposed between the heater 435 and the heating plate 431.

In addition, an adiabatic plate made of material, such as mica, is further provided to prevent heat of the heater 435 from being transferred to the casing 410b. Furthermore, a heater fuse and a fuse fastening spring for holding the heater fuse may be further provided in the casing.

In the portable hair iron which is supplied with the battery having a limited amount of electric energy, it is important to reduce energy loss occurring during a heat transfer process. If the heating plate 431 is made of magnesium or a magnesium alloy and is reduced in thickness, the weight of the hair iron can be reduced, and a resistance of heat transfer is reduced, thus enhancing the heat efficiency of the hair iron. Furthermore, it is conceivable that the portable hair iron is used after it is connected to a typical electric outlet. Therefore, the structure for prevention of leakage of electricity is preferably applied to this embodiment in the same manner as that of the prior embodiments. Due to the requirement of double electrical insulation, if an insulation sheet which has heat conductivity lower than that of metal or an oxide film is provided between the heater and the heating plate, the temperature of normal use of the heating plate is reduced and a heat loss is increased, as described in the explanation of the conventional technique. Therefore, in the present invention, the heating plate is made of magnesium or a magnesium alloy which is coated with an oxide film. Thus, the thickness thereof can be reduced compared to that of the hair iron of the conventional technique, so that a reduction in temperature of the heating plate and a heat loss thereof can be prevented despite the heating plate maintaining the mechanical strength. For example, the heating plate can have a thickness ranging from 0.8mm to 1.2mm and, more preferably, the thickness thereof is 1mm or less.

As described above, in a hair iron according to the present invention, the thickness and weight of a heating plate can be reduced, despite maintaining the mechanical strength and the heat transfer efficiency of the heating plate to a degree similar to those of the conventional aluminum heating plate. Therefore, the portability and convenience can be enhanced.

Furthermore, because the thickness of the heating plate can be reduced despite ensuring the strength and the shape stability, the design of the hair iron can be variously changed, and it can satisfy the recent trend towards lightness, thinness, shortness and smallness.

Moreover, the hair iron according to the present invention improves the structure for electrical insulation, so that electrical shock can be reliably prevented, and the mechanical strength and the heating efficiency of the heating plate can be equivalent to those of the conventional technique.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope of the invention as disclosed in the accompanying claims.

Claims

CLAIMS1. A hair iron, comprising a heating part to heat and style hair, the heating part comprising: a heating plate; and a heater to transfer heat to the heating plate, the heater having an electric wire through which electric currents flow, wherein the heating plate is made of magnesium or a magnesium alloy and is treated by anodizing.
2. The hair iron as set forth in claim 1, wherein the heating plate is made of the magnesium alloy, wherein the magnesium alloy contains 2% to 8.5% aluminum and 90% or more of magnesium.
3. The hair iron as set forth in claim 1 or 2, wherein a heat-resistant synthetic resin coating is applied to an inner surface of the heating plate which faces the heater.
4. The hair iron as set forth in any preceding claim, wherein a ceramic coating is applied to at least a portion of a surface of the heating plate, the portion being brought into contact with the hair.
5. The hair iron as set forth in any preceding claim, being a portable hair iron having a rechargeable battery.
6. The hair iron as set forth in any preceding claim, wherein the heating plate has a thickness ranging from 0.8 mm to 1.2 mm.
7. The hair iron as set forth in any preceding claim, wherein the heater is coated with a double electrical insulation film.
8. The hair iron as set forth in claim 7, wherein the doable electrical insulation film is made of polyimide.
9. The hair iron as set forth in any preceding claim, wherein a fuse is provided on a first surface of the heater opposing to a second surface of the heater facing the heater plate, wherein the heater, the heating plate and the fuse are closely coupled to each other by a fuse fastening spring.
10. The hair iron as set forth in claim 9, wherein the fuse fastening spring comprises: a rectangular rim-shaped frame made of an elastic steel plate; heater pressing pieces extending outwards from edges of both longitudinal ends of the rectangular rim-shaped frame, the heater pressing pieces being bent towards the heating plate to press the heater such that the heater is brought into close contact with the heating plate; fastening pieces extending outwards from the rectangular rim-shaped frame in the lateral direction, the fastening pieces being coupled to the heating plate; a fuse pushing piece protruding inwards from the rectangular rim-shaped frame, the fuse pushing piece being double bent such that the fuse which is in contact with the first surface of the heater is pushed towards the heater by the fuse pushing piece.
11. A hair iron, comprising: an upper casing and a lower casing each having a heater installation part and a handle part with respect to a longitudinal direction, the handle parts of the upper and lower casings being coupled at corresponding ends thereof to each other by a hinge; a heating plate installed on each of facing inner surfaces of the heater installation parts of the upper and lower casings; and a heater to transfer heat to the heating plate, the heater having an electric wire to generate heat, wherein the heater is coated with a double insulation film.
12. A hair iron substantially as described herein with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.
13. A hair iron substantially as described herein with reference to and as illustrated in Figures 4 to 6 of the accompanying drawings.
14. A hair iron substantially as described herein with reference to and as illustrated in Figure 7 of the accompanying drawings.
15. A hair iron substantially as described herein with reference to and as illustrated in Figure 8 of the accompanying drawings.