WO2008030064A1

WO2008030064A1 - An assembly structure of a heater and a heating plate of a hair iron for improving characteristics of electrical insulation

Info

Publication number: WO2008030064A1
Application number: PCT/KR2007/004343
Authority: WO
Inventors: Dong-Hyun Yun
Original assignee: CAOS Co Ltd
Current assignee: CAOS Co Ltd
Priority date: 2006-09-07
Filing date: 2007-09-07
Publication date: 2008-03-13
Anticipated expiration: 2009-03-07

Abstract

The present invention relates to an assembly structure for a heater and a heating plate of a hair iron with electrical insulation. More specifically, the present invention prevents leakage of a current flowing from a heater to a heating plate and prevents breakdown of the heater by thermal shock or physical impact at the elevated temperature as well as the room temperature. An assembly structure for a heater and a heating plate of a hair iron with electrical insulation comprising: a heater configured to be mounted on a heating plate having a protrudent sill, wherein the heater is fixed by a fixing spring; a ceramic plate configured to transfer heat from the heater to the heating plate, wherein the ceramic plate is constructed from a high thermal conductive ceramic material; and a electrical insulation sheet is configured to prevent breakdown of the heater by physical or thermal shock at room temperature and high temperature, wherein the electrical insulation sheet is mounted on the upper part of the heater and relieves pressing force by the fixing spring to the heater.

Description

AN ASSEMBLY STRUCTURE OF A HEATER AND A HEATING PLATE OF A HAIR IRON FOR IMPROVING CHARACTERISTICS OF ELECTRICAL INSULATION

Technical Field

[1] The present invention relates to an assembly structure of a heater and a heating plate of a hair iron for improving characteristics of electrical insulation between the heater and the heating plate.

[2] More particularly, the present invention relates to an assembly structure of a heater and a heating plate of a hair iron for improving characteristics of electrical insulation by using a high thermal conductive ceramic plate, wherein said high thermal conductive ceramic plate is used to prevent leakage of a current flowing from the heater to the heating plate and to prevent the breakdown of the heater by thermal shock or physical impact at the elevated temperature as well as at the room temperature.

[3] In addition, the present invention relates to an assembly structure of a heater and a heating plate of a hair iron for improving characteristics of electrical insulation, wherein the assembly structure is provided by mounting an electrical insulation structure in a space between the upper side and lateral side of the heater and the heating plate and thus within the inner space of the heating plate, thereby occupies the space by the electrical insulation structure to maintain a creepage distance between the heater and the heating plate at more than a selected distance.

[4]

Background Art

[5] The assembly structure of the heater and the heating plate of an hair iron using a PTC heating element as shown in Fig. 1 is generally used in the hair iron in the art. The assembly comprises the heating plate (20) on which a substrate (21) and electrodes (22) are positioned and the electrical insulation layer (23) positioned outside of the heating plate. The PTC heating element being used is constructed from a PTC material having the characteristic that the resistance value increases when the temperature rises, and a metal conductor serves as electrodes on both sides of the PTC material.

[6] Therefore, the assembly structure of the hair iron according to the prior art has the disadvantage that an electrical insulation film or tape should be used to insulate the exposed metal electrodes in order to protect the heater, and thus the heat generated from the heater cannot be transferred efficiently to the heating plate due to the used electrical insulation film with low thermal conductivity.

[7] Fig. 2 shows a developed perspective view of a ceramic heater according to the prior art. The present ceramic heater is produced by printing a heating element (31) on a ceramic plate (30) with high thermal conductivity, covering the heating element (31) with the another ceramic plate (32) and then sintering it by heat treatment at the elevated temperature (at least 1000⁰C)

[8] The present ceramic heater has a disadvantage that since the ceramic heater is produced by printing the heating element on the ceramic plate with high thermal conductivity, covering the heating element with the another ceramic plate, and then sintering it by heat treatment, the resultant ceramic heater cannot meet the standards for electrical safety in relation to a thickness providing suitable electrical insulation due to the technical limitation.

[9] Fig. 3 and Fig. 4 show perspective views of an assembly structure of a heater and a heating plate of a hair iron according to the prior art. As can be seen from Fig. 3 and Fig. 4, the present assembly structure comprises a heating plate (10), a heater (13), and a fixing spring (16) wherein said heater is inserted into the heating plate and is fixed on the heating plate by the fixing spring. The present assembly structure has an advantage that the heat generated from the heater is directly transferred to the heating plate, thereby increasing the temperature of the heating plate fast and efficiently and making the control of the temperature of the heating plate easier.

[10] However, since electrical insulation property of the present assembly structure depends on electrical insulation property of the heater, the present assembly structure does not meet the standards for electrical safety in relation to a safety test of dielectric strength (i.e., the test of determining the safety by applying 1,000 to 4,000 AVC voltage to the final product) and a safety test of leakage current (i.e., the test of determining the amount of the current leakage occurring during the use of the product).

[11] In addition, the present assembly structure has a disadvantage that since the heater is directly subjected to the pressure of the fixing spring it can be easily broken at the elevated temperature due to local stress on the surface of the heater by the pressure, and can be easily broken by the physical impact at the room temperature and the elevated temperature. The present assembly structure also has a disadvantage that when the heater is broken, the metal heating element inside of the heater can be exposed, thereby causing an electric shock to the user during use.

[12] Fig. 5 and Fig. 6 show perspective views of an assembly structure of a heater and a heating plate of another hair iron according to the prior art. As can be seen from Fig. 5 and Fig. 6, the present assembly structure comprises a heating plate (10), a heater (13),an insulation film (19) and a fixing spring (16) wherein the whole surfaces of the heater (13) to be inserted to the heating plate (10) are wrapped by an insulation film (19) which is dipped into high temperature thermal grease before assembling it with the heating plate (10) and wherein the heater (13) is fixed by the fixing spring (16) at the upper part thereof.

[13] This kind of assembly structure has an advantage that the requirements of the standards for electrical safety are satisfied by protecting the heater using a polymer film with good electrical insulation and dielectric strength property, and the heater endures the physical impact at the room temperature and the elevated temperature by using a flexible polymer based insulation film and the physical stress by the fixing spring is also reduced accordingly.

[14] However, the heat conductivity of most polymers is lower than lW/mK (for example, the heat conductivity of the polyimide film is about 0.8W/m). Therefore, the heat generated from the heater cannot be transferred efficiently to the heating plate. As a result, when the heater is operated, the rising of the temperature of the heating plate is delayed due to the low heat conductivity and thus it is difficult to control the temperature of the heating plate and to maintain a setting temperature of the heating plate.

[15]

Disclosure of Invention Technical Problem

[16] According to the prior art, the heat generated from the heater cannot be transferred efficiently to the heating plate. As a result, when the heater is operated, the rising of the temperature of the heating plate is delayed due to the low heat conductivity and thus it is difficult to control the temperature of the heating plate and to maintain a setting temperature of the heating plate.

[17]

Technical Solution

[18] The object of the present invention is to provide an assembly structure of a heater and a heating plate of a hair iron, comprising a ceramic plate with high thermal conductivity and electrical insulation property by which the heat generated from the heater is transferred to the heating plate fast and efficiently and leakage of current flowing from the heater to the heating plate is prevented.

[19] Another object of the present invention is to provide an assembly structure of a heater and a heating plate of a hair iron, comprising a ceramic plate with high thermal conductivity and electrical insulation property and an electrical insulation sheet by which high electrical insulation between the heater and the heating plating is maintained, the emission of the heat from the upper side of the heater is prevented and the heater is prevented from breaking down by physical impact or thermal shock at the elevated temperature as well as at the room temperature.

[20] In an additional aspect, the object of the present invention is to provide an assembly structure of a heater and a heating plate of a hair iron wherein said assembly structure is adapted to maintain a clearance at more than a selected distance between a electrical conduction member and a metal member, wherein electrical power is applied the electrical conduction member and a human body contacts with a metal member. [21] In a further aspect, the object of the present invention is to provide an assembly structure of a heater and a heating plate of a hair iron wherein said assembly structure is adapted to maintain a creepage distance of more than a clearance between an electrical conduction member and a metal member by inserting an electrical insulation structure between them. The creepage distance, the term used herein, refers to a nearest distance between the adjusting subjects or the surfaces thereof.

Advantageous Effects

[22] The assembly structure of the present invention transfers the heat from the heater to the heating plate fast and effectively through the ceramic plate with high thermal conductivity, prevents leakage of current flowing from the heater to the heating plate by making the ceramic plate fairly broader than the heater in width and length and thus prevents accidents of electrical shock.

[23] The electrical insulation sheet used in the present invention has high electrical insulation and heat insulation properties while reducing thermal shock or physical impact of the heater at the elevated temperature as well as at the room temperature by relieving the pressing force of the fixing spring to the heater.

[24] The high temperature grease used in the present invention prevents formation of an air gap between the heating plate and the ceramic plate and between the ceramic plate and the heater, wherein the coefficient of thermal expansions are different to each other.

[25] In addition, according to the assembly structure of the present invention, a clearance, i.e., an insulation space is occupied by the insulation structure of solid insulation materials to maintain the creepage distance at more than the clearance and meet the standards for electrical safety in relation to suitable electrical insulation.

[26] The insulation structure according to the present invention can be adjusted to maintain the creepage distance at a selected distance regardless of the length and width of the heating plate.

[27] The present invention provides an assembly structure of a heater and a heating plate of a hair iron wherein an electrical insulation structure is mounted by assembling it in the inner space of the heating plate to prevent an assembly error and thus maintain the heater and the ceramic plate at a selected position.

[28] Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. [29]

Brief Description of the Drawings

[30] Fig. 1 shows a developed perspective view of the structure of a PTC heater according to the prior art. [31] Fig. 2 shows a developed perspective view of the structure of a ceramic heater according to the prior art. [32] Fig. 3 shows a developed perspective view of the assembly structure between a heater and a heating plate of a hair iron according to the prior art. [33] Fig. 4 shows an assembled status view of the assembly structure of Fig. 3.

[34] Fig. 5 shows a developed perspective view of another assembly structure between a heater and a heating plate of a hair iron according to the prior art. [35] Fig. 6 shows an assembled status view of the assembly structure of Fig. 5.

[36] Fig. 7 shows a developed perspective view of an assembly structure according to the preferred embodiment of the present invention. [37] Fig. 8 shows a front cross-sectional view of the assembled status of an assembly structure according to the present invention. [38] Fig. 9 shows enlarged cross-sectional view of the assembled status of an assembly structure according to the present invention. [39] Fig. 10 shows a side cross-sectional view of the assembled status of an assembly structure according to the present invention. [40] Fig. 11 is a graph which shows comparison of the temperatures on the surfaces of heating plates of the hair irons according to assembly structures according to the prior art and the present invention. [41] Fig. 12 is a side view of an assembly structure according to a preferred embodiment of the present invention.

[42] Fig. 13 is a front view of the assemble structure as depicted in fig. 12.

[43] Fig. 14 is a developed perspective view of the assembly structure as depicted in fig.

12. [44] Fig. 15 is a side view of another assembly structure according to another preferred embodiment of the present invention.

[45] Fig. 16 is a front view of the assemble structure as depicted in fig. 15.

[46] Fig. 17 is a developed perspective view of the assembly structure as depicted in fig.

15. [47]

Best Mode for Carrying Out the Invention [48] The present invention provides an assembly structure of a heater and a heating plate of a hair iron, comprising a ceramic plate with high thermal conductivity and electrical insulation property by which the heat generated from the heater is transferred to the heating plate fast and efficiently and leakage of a current flowing from the heater to the heating plate is prevented.

[49] The present invention also provides an assembly structure of a heater and a heating plate of a hair iron, comprising a ceramic plate with high thermal conductivity and electrical insulation property by which the heat generated from the heater is transferred to the heating plate fast and efficiently and leakage of a current flowing from the heater to the heating plate is prevented; and a electrical insulation sheet by which high electrical insulation between the heater and the heating plating is maintained, the emi ssion of the heat from the upper side of the heater is prevented and the heater is prevented from breaking down by physical impact or thermal shock at the elevated temperature as well as at the room temperature.

[50]

Mode for the Invention

[51] Fig. 7 to Fig. 10 show an assembly structure of a heater and a heating plate of a hair iron according to the preferred embodiment of the present invention. Fig. 7 shows a developed perspective view of the assembly structure. Fig. 8 shows a front cross- sectional view of the assembled status. Fig. 9 shows enlarged cross-sectional view of the assembled status. Fig. 10 shows a side cross-sectional view of the assembled status.

[52] The heating plate (10) is formed by extrusion of metal, and in principle, is formed by extrusion of aluminum. The heating plate has a protrudent sill (11) at an upper area inside of the heating plate along the longitudinal direction thereof. The heater (13) can be positioned on the inside of the heating plate (10).

[53] A ceramic plate (12) is sandwiched between the heating plate (lθ)and the heater (13).

The ceramic plate (12) is constructed from high thermal conductive ceramic material such as Al O (thermal conductivity of the ceramic plate therefrom: 20W/mK) or MgO.

[54] The heat conductivity of the ceramic plate is reinforced by spraying or coating thermal grease such as silicon grease with high thermal conductivity on upper side and bottom side of the ceramic plate to minimize air gap.

[55] The heater (13) is mounted on the ceramic plate (12) in such a way that an electric wire (14) is extended to the outside and a part of the electric wire (14) is coated with insulation tube. The heater (13) which is coated by an insulation tube is established. An electrical insulation sheet (15) is mounted on the upper side of the heater (13).

[56] The ceramic plate (12) is fairly broader than the heater (13) in the width and length.

The electrical insulation sheet (15) is also fairly broader than the heater (13) in the width and length. [57] The electrical insulation sheet (15) is in the form of sheet, pad, or tape and is produced from materials with good insulation property, such as silicon, fluoric resin, or polyimide. The electrical insulation sheet (15) is fixed by a fixing spring (16) thereon, and if required, it is possible to establish a pressing plate (17) between the fixing spring (16) and the electrical insulation sheet (15).

[58] The heating plate (10) used in the present invention can be formed by extrusion of metallic materials, preferably aluminum materials. The heater (13)is mounted on the inner surface of the heating plate (10).

[59] In one aspect, the clearance (28) between the heating plate (10) and the heater (13) is occupied by a ceramic plate (26) formed from ceramic materials such as alumina (Al O ), magnesia (MgO), or zirconia (ZrO ), etc. with high thermal conductivity and electrical conductivity to maintain the creepage distance (27, 27a) between the heater (13) and the heating plate (10) at more than a selected distance.

[60] In an additional aspect, the heater (13) has an insulation molding (33) which is protruded toward the insulation tube (34) which is wrapping the wire (14) as the central figure. The heater (13) is connected to the wire (14) covered by the insulation tube (34) and electrical power is supplied to the heater (13) to heat the heating plate (10) to a selected temperature.

[61] In a further aspect, the clearance between the upper side and the lateral side of the heater (13) and the metallic heating plate (23) is occupied by the insulation structure (32) formed by solid insulation materials such as ceramic materials or thermal resistance polymer materials (ex., nylon resin, or fluorine resin, etc.) with high electrical insulation to maintain the creepage distance (27, 27a) between the heater (13) and the metallic heating plate (23) at more than a selected distance.

[62] In a still further aspect, the assembly structure of the present invention can be assembled to maintain the position of the heater (13) and the ceramic plate (26) positioned in the inner space of the heating plate (10) by using the insulation structure (32) and thus improve assembly property and reproductivity of the article.

[63] In a still further aspect, a leaf spring (30) is laid on the insulation structure (32) and fixed by a spring strength adjusting bolt (31).

[64] In a still further aspect, if the length and the width of the heating plate (10) is short, the thickness of the ceramic plate (260 and the insulation structure (32) can be adjusted to maintain the creepage distance (27, 27a) at more than a selected distance.

[65] The assembly structure of the present invention as described above can transfer the heat generated from the heater (13) to the heating plate (10) fast and effectively through the ceramic plate (12) with high thermal conductivity sandwiched between them.

[66] The electrical insulation breakdown voltage of Al O is about 10,000 V/mm which is regarded as ensuring high electrical insulation. Therefore, by sandwiching the ceramic plate (12) fairly broader than the heater (13) in the width and length between heating plate (10) and the heater (13), it is possible to prevent leakage of a current flowing from the heater (13) to the heating plate (10) and thus prevent accidents of electrical shock.

[67] The electrical insulation sheet (15) which is mounted on the upper area of the heater

(13) can be constructed from a variety of elastic materials with high electrical insulation and heat insulation properties.

[68] The elasticity of the insulation sheet protects the heater (13) from breaking down at the elevated temperature by relieving a pressing force from the fixing spring to the heater (13) and protects the heater (13) from breaking down by physical impact and thermal shock at room temperature and elevated temperature.

[69] The high thermal grease (18) which is coated on the ceramic plate (12) prevents formation of an air layer between the heating plate (10) and the ceramic plate (12). In addition, the thermal grease (18) serves to increases heat conductivity and keep a stable connection among heating plate (10), the ceramic plate (12), and the heater (13) of which the coefficient of thermal expansions are different to each other.

[70] Fig. 11 is a graph which compares the temperatures of surfaces of heating plates of the hair irons according to the prior art and the present invention. As shown in Fig. 11, the temperature curve of the assembly structure of the heater with the heating plate according to the prior art shows W shape which represents the increase and decrease of the temperature. However, the temperature curve of the assembly structure according to the present invention is almost the same as the graph of the heater current control temperature in connection with increase, decrease and maintenance of the temperature. In addition, the assembly structure of the heater with the heating plate according to the prior art results in the overheating. However, in the present invention, the increasing of the temperature occurs fast and maintains at that temperature for a time.

[71] The assembly structure of the present invention as described above can transfer the heat generated from the heater (13) to the heating plate (10) fast and effectively through the ceramic plate (26) with high thermal conductivity on the upper side of the heating plate(lθ).

[72] According to one aspect of the assembly structure of the present invention, the heater

(13) generates the heat by electrical current from the outer wire (14). The clearance between the upper side and the lateral side of the heater (13) and the metallic heating plate (10) is occupied by the insulation structure (32) formed by solid insulation materials such as ceramic materials or thermal resistance polymer materials (ex., nylon resin, or fluorine resin, etc.) with high electrical insulation to maintain the creepage distance (27, 27a) between the heater (13) and the metallic heating plate (10) at more than a selected distance and thus meet the standards for electrical safety in relation to suitable electrical insulation. As a result, the present invention provides an assembly structure of a heater and a heating plate of a hair iron wherein said assembly structure is adapted to maintain the clearance (28) between a electrical conduction member to which electrical power is applied and a metal member with which a human body contacts at more than a selected distance and thus can be assembled on position to prevent any assembly error.

[73] The ceramic plate (26) formed from ceramic materials such as alumina (Al O ), magnesia (MgO), or zirconia (ZrO ), etc. with high thermal conductivity and electrical insulation is inserted into the clearance (28) between the heating plate(lθ) and the heater (13) to maintain the creepage distance (27, 27a) between the heater (13) and the heating plate (10) at more than a selected distance.

[74] The insulation structure (32) is assembled together with an electrical insulation sheet

(25), the heater (13) and the ceramic plate (26) to maintain the heater (13) and the ceramic plate (26) in the inner space of the heating plate (10) at a selected position and thus improve assembly property and reproductivity of the article.

[75] If the length and the width of the heating plate(lθ) is too short, since the creepage distance (27, 27a) between the heater (13) and the heating plate (10) can be short accordingly, the thickness of the ceramic plate (26)and the insulation structure (32) should be adjusted to maintain the creepage distance (27, 27a) at more than a selected distance.

[76] Each of Fig. 15, Fig. 16 and Fig 17 is a side view, a front view and a developed view of an assembly structure of a heater and a heating plate of a hair iron according to another embodiment of the present invention.

[77] According to the above Figs., the heater (13) is mounted on the upper side of the ceramic plate (26) positioned in the inner space of the heating plate (10), and the ceramic plate (26) with high electrical insulation property and high thermal conductivity is positioned between the heating plate (10) and the heater (13) to maintain the creepage distance (27, 27a) at more than a selected distance.

[78] The heater (13) has an insulation molding (33) which is protruded toward the insulation tube (34) which is wrapping the wire (14) as the central figure. The heater (13) is connected to the wire (14) covered by the insulation tube (34) and electrical power is supplied to the heater (13) to heat the heating plate (10) to a selected temperature.

[79] The clearance between the upper side and the lateral side of the heater (13) and the metallic heating plate (10) is occupied by the insulation structure (32) of solid insulation to maintain the creepage distance (27, 27a) between the heater (13) and the metallic heating plate (10) at more than a selected distance. [80] The insulation structure (32) is fixed on the heating plate (10) by a leaf spring (30).

[81]

Industrial Applicability

[82] The assembly structure of the present invention transfers the heat from the heater to the heating plate fast and effectively through the ceramic plate with high thermal conductivity, prevents leakage of current flowing from the heater to the heating plate by making the ceramic plate fairly broader than the heater in width and length and thus prevents accidents of electrical shock.

[83] The electrical insulation sheet used in the present invention has high electrical insulation and heat insulation properties while reducing thermal shock or physical impact of the heater at the elevated temperature as well as at the room temperature by relieving the pressing force of the fixing spring to the heater.

[84] The high temperature grease used in the present invention prevents formation of an air gap between the heating plate and the ceramic plate and between the ceramic plate and the heater, wherein the coefficient of thermal expansions are different to each other.

[85] In addition, according to the assembly structure of the present invention, a clearance, i.e., an insulation space is occupied by the insulation structure of solid insulation materials to maintain the creepage distance at more than the clearance and meet the standards for electrical safety in relation to suitable electrical insulation.

[86] The insulation structure according to the present invention can be adjusted to maintain the creepage distance at a selected distance regardless of the length and width of the heating plate.

[87] The present invention provides an assembly structure of a heater and a heating plate of a hair iron wherein an electrical insulation structure is mounted by assembling it in the inner space of the heating plate to prevent an assembly error and thus maintain the heater and the ceramic plate at a selected position.

Claims

[1] An assembly structure of a heater (13) and a heating plate (10) of a hair iron which is constructed by mounting the heater on the heating plate (10) with a protrudent sill (11) and fixing the heater to the heating plate by a fixing spring, characterized in that the assembly structure comprises a ceramic plate (12) with high thermal conductivity which is inserted between the heater and the heating plate to transfer heat from the heater to the heating plate; and an electrical insulation sheet (15) which is mounted on the upper side of the heater to prevent breakdown of the heater at an elevated temperature as well as the room temperature by reducing the force from the fixing spring, wherein said ceramic plate with high thermal conductivity provides improved characteristics of electrical insulation.

[2] The assembly structure according to claim 1, wherein the ceramic plate is constructed from a high thermal conductive and electrical insulating material selected from the group consisting of Al O MgO, ZrO and the combination thereof.

[3] The assembly structure according to claim 1, wherein the electrical insulation sheet is constructed from a elastic material with high electrical insulation property selected from the group consisting of silicon, fluoric resin and polyimide and the combinations thereof.

[4] The assembly structure according to claim 1, wherein the ceramic plate is fairly broader than the heater in the width and length.

[5] The assembly structure according to claim 1, wherein the electrical insulation sheet is fairly broader than the heater in the width and length.

[6] An assembly structure of a heater and a heating plate of a hair iron which is constructed by mounting the heater on the heating plate and fixing the heater to the heating plate, characterized in that clearance (28) between the upper side and the lateral side of the heater (13) and the heating plate (10) are occupied by an electrical insulation structure (32) formed by solid insulation materials to maintain the creepage distance (27, 27a) between the heater (13) and the heating plate (10) at more than a selected distance, wherein said electrical insulation structure positioned in the inner space of the heating plate provides improved characteristics of electrical insulation.

[7] The assembly structure according to claim 6, wherein the clearance (28) is occupied by the insulation structure (32) formed by solid insulation materials such as ceramic materials or thermal resistance polymer materials for example, nylon resin, or fluorine resin, etc. to maintain the creepage distance (27, 27a) between the heater (13) and the metallic heating plate (10) at more than a selected distance. [8] The assembly structure according to claim 6, wherein the clearance (28) is occupied by assembling an electrical insulation structure (32) between the upper side and the lateral side of the heater (13) and the heating plate (10) to maintain the creepage distance (27, 27a) between the heater (13) and the metallic heating plate (10) at more than a selected distance.