阅读说明：本技术 电加热器 (Electric heater ) 是由 宋美善 权裕硕 于 2019-08-21 设计创作，主要内容包括：本发明涉及应用于烹饪设备的电加热器,尤其涉及一种包括面状发热体的电加热器,所述面状发热体即使在有限的面积内形成电极部也能有效地降低电极部的发热温度。本发明的电加热器包括：基板(Substrate：能够在绝缘基板表面形成导体图案的绝缘材料)；以及面状发热体(an plane heating element),其形成于所述基板的一表面；所述面状发热体包括：图案部,使所述图案部的始点和终点相连接；以及电极部,其与所述图案部的始点和终点相连接,所述电极部的厚度大于所述图案部的厚度。(The present invention relates to an electric heater applied to a cooking apparatus, and more particularly, to an electric heater including a planar heat generating body capable of effectively reducing a heat generation temperature of an electrode portion even if the electrode portion is formed in a limited area. The electric heater of the present invention comprises: a Substrate (Substrate: an insulating material capable of forming a conductor pattern on a surface of an insulating Substrate); and a planar heating element (an planar heating element) formed on one surface of the substrate; the planar heating element includes: a pattern section connecting a start point and an end point of the pattern section; and an electrode portion connected to a start point and an end point of the pattern portion, the electrode portion having a thickness greater than that of the pattern portion.)

1. An electric heater, comprising:

a substrate; and

a planar heating element formed on one surface of the substrate;

the planar heating element includes:

a pattern section connecting a start point and an end point of the pattern section; and

an electrode section connected to a start point and an end point of the pattern section,

the electrode part has a thickness greater than that of the pattern part.

2. The electric heater of claim 1,

the electrode section includes:

an anode electrode located outside the pattern part and connected to a start point of the pattern part; and

and a cathode electrode disposed outside the pattern part in a horizontal manner with the anode electrode and connected to an end point of the pattern part.

3. The electric heater of claim 1,

the pattern part includes:

a plurality of circular arc-shaped rails spaced apart from each other and extending from the inside of the pattern portion toward the outside; and

a plurality of bridges connecting the plurality of rails in series.

4. The electric heater of claim 3,

the pattern portion is formed in a symmetrical shape with respect to a reference line passing through a center of the pattern portion.

5. The electric heater of claim 3,

the electrode portion is formed to have a thickness greater than that of the rail.

6. The electric heater of claim 5,

the thickness of the electrode part is formed in the range of 1.3-2.0 times of the thickness of the rail.

7. The electric heater of claim 5,

the electrode portion generates heat to 200 ℃ or lower while the current flows.

8. The electric heater of claim 3,

the bridge is formed to have a thickness greater than that of the rail.

9. The electric heater of claim 8,

the thickness of the bridge is formed within the range of 1.3-2.0 times of the thickness of the rail.

10. The electric heater of claim 8,

the bridge heats to below 500 ℃ during the current flow.

11. The electric heater according to any one of claims 1 to 10, wherein the planar heat generating body comprises:

an inner planar heating element formed at the center of the planar heating element; and

one or more outer surface heating elements provided so as to surround the inner surface heating elements, the electrode unit including:

an inner electrode portion for supplying current to the inner planar heating element; and

and an outer electrode section for supplying current to the outer planar heating element.

Technical Field

The present invention relates to an electric heater applied to a cooking apparatus, and more particularly, to an electric heater including a planar heat generating body capable of effectively reducing a heat generation temperature of an electrode portion even if the electrode portion is formed in a limited area.

Background

In general, a cooking device is a device that cooks an object by heating the object with gas or electricity, and various products such as a microwave oven using microwaves, an oven using a heater, a gas range using gas, an electric range using electricity, and a cooktop (cooktop) having a gas range or an electric range built therein are widely used.

In the gas range, a flame is directly generated using gas as a heat source, and in contrast, an electric range heats a container and food placed on an upper plate using gas and electricity.

In the gas range, heat loss due to flame is large, and pollutants are discharged and pollute indoor air as the gas range is incompletely combusted, so that the electric range has attracted attention in recent years.

Electric cookers can be divided into: an induction cooker (induction) for directly heating the magnetic container by magnetic induction; an electric ceramic furnace (Hi-light) for heating the upper surface of the ceramic by a hot wire.

For the induction cooker, the cooking time at high temperature is short, but a special container having magnetism is required. In contrast, in the case of the electric ceramic oven, although the existing container is directly used, the cooking time is relatively long.

In the conventional electric ceramic furnace, a heating element using a nickel chromium wire is used, but an electric heater using a planar heating element is being developed in order to make the thickness of the heating element thin.

In addition, in order to shorten the cooking time, an electric ceramic oven using an electric heater capable of heating a limited area to a high temperature has been developed.

As an example of such an electric heater, there is a planar heat generating device disclosed in korean patent laid-open publication No. 10-1762159B1 (08/04/2017), which includes: a substrate, the surface of which is made of an electrically insulating material; a heating element attached to a surface of the substrate and arranged in a predetermined shape; and a power supply unit for supplying power to the heating element.

In the electric heater as described above, the temperature distribution of the heating target may vary depending on the arrangement shape (i.e., pattern) of the planar heating element, and the planar heating element is preferably formed in a shape or form that can uniformly heat the heating target to the maximum extent possible.

The planar heating element of the electric heater includes a plurality of linear or arc-shaped rails (tracks), and adjacent rails among the plurality of rails may have a shape connected by a bridge (or a track).

As another example of the heater, there is a Temperature sensitive device (Temperature sensitive device) disclosed in european patent publication EP0,228,808A2 (published 1987, 07/15), which is configured such that a heater track and a pair of electrodes, which are conductive materials, are printed on a ceramic coating, and radiant heat is generated from the heater track by the electrodes as current is supplied.

Disclosure of Invention

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an electric heater including a planar heat generating element capable of greatly reducing the resistance of an electrode in a limited area.

Another object of the present invention is to provide an electric heater including a planar heat generating element that can prevent local heat generation even if a large current density difference is generated inside a pattern portion.

The present invention provides an electric heater, comprising: a Substrate (Substrate: an insulating material capable of forming a conductor pattern on a surface of an insulating Substrate); and a planar heating element (an planar heating element) formed on one surface of the substrate; the planar heating element includes: a pattern section connecting a start point and an end point of the pattern section; and an electrode portion connected to a start point and an end point of the pattern portion, the electrode portion being formed to have a thickness greater than that of the pattern portion. Therefore, the resistance of the electrode in a limited area can be greatly reduced, thereby forming a non-heat-generating portion.

At this time, the electrode part may include: an anode electrode located outside the pattern part and connected to a start point of the pattern part; and a cathode electrode disposed outside the pattern portion in a horizontal manner with the anode electrode, and connected to an end point of the pattern portion.

In addition, in the present invention, the pattern part may include: a plurality of circular arc-shaped rails spaced apart from each other and extending from the inside of the pattern portion toward the outside; and a plurality of bridges connecting the plurality of rails in series.

At this time, the pattern part may be formed in a symmetrical shape with respect to a reference line passing through the center of the pattern part.

In the present invention, the electrode part is formed to have a thickness greater than that of the rail, the electrode part may be formed to have a thickness 1.3 to 2.0 times that of the plurality of rails, and the electrode part generates heat to 200 ℃ or less while a current flows.

In addition, in the present invention, the thickness of the bridge is formed to be greater than that of the rails, the thickness of the bridge may be formed in a range of 1.3 to 2.0 times the thickness of the plurality of rails, and the bridge generates heat to 500 ℃ or less while current flows.

Therefore, even if a large density difference is generated by the current flowing along the bridge, since the resistance of the bridge is formed to be small, it is possible to prevent local heat generation of the bridge portion and dielectric breakdown caused by the local heat generation.

In the present invention, the planar heat generating element further includes: an inner planar heating element formed at the center of the planar heating element; and at least one or more outer surface heating elements provided so as to surround the inner surface heating elements, the electrode unit including: an inner electrode portion for supplying current to the inner planar heating element; and an outer electrode portion for supplying current to the outer surface heating element. That is, by forming a plurality of patterns, the heat generation intensity in a plurality of stages can be realized.

According to the electric heater of the present invention, even if the electrode portion is formed in a limited area, the resistance of the electrode portion can be significantly reduced by forming the thickness of the electrode portion to be larger than that of the pattern portion. Therefore, the heat generation temperature of the electrode portion formed in the limited area can be effectively reduced.

In the pattern portion of the present invention, the bridge having a large current density difference at the center of the pattern portion is formed to have a thickness larger than that of the track, whereby the bridge resistance can be significantly reduced. Therefore, the bridge portion in the pattern portion can be prevented from generating local heat and the heat line can be prevented from being damaged, and the entire area formed by the pattern portion can be uniformly heated.

In the present invention, a plurality of pattern portions are formed in the same plane, whereby heat generation intensity in a plurality of stages can be provided. Therefore, a limited area can be heated to a high temperature in a stepwise manner.

Drawings

Fig. 1 is a perspective view illustrating an electric range to which an electric heater according to an embodiment of the present invention is applied.

Fig. 2 is a control block diagram of an electric cooker to which an electric heater according to an embodiment of the present invention is applied.

Fig. 3 is a sectional view showing an electric heater according to an embodiment of the present invention.

Fig. 4 is a plan view showing a single (single) sheet heating element according to an embodiment of the present invention.

Fig. 5A and 5B are sectional views taken along line a-a 'and line B-B' of fig. 4.

FIG. 6 is a plan view showing a double (dual) planar heat generating element according to an embodiment of the present invention.

Fig. 7A and 7B are sectional views taken along line C-C 'and line D-D' of fig. 6.

Fig. 8 is a plan view showing a triple (triple) planar heat generating element according to an embodiment of the present invention.

Fig. 9A and 9B are sectional views taken along lines E-E 'and F-F' of fig. 8.

Description of the reference numerals

100: planar heating element 110: pattern part

111: the track 112: bridge with a bridge body

120: the electrode portion 121: anode electrode

122: cathode electrode

Detailed Description

The present embodiment will be described in detail below with reference to the drawings. However, the contents disclosed in the present embodiment can determine the scope of the inventive idea possessed by the present embodiment, and the inventive idea possessed by the present embodiment includes implementation variations such as addition, deletion, and modification of the constituent elements to the mentioned embodiment.

Fig. 1 is a perspective view illustrating an electric range to which an electric heater according to an embodiment of the present invention is applied, and fig. 2 is a control block diagram of the electric range to which the electric heater according to the embodiment of the present invention is applied.

The electric heater 1 of the present invention may constitute a part of an electric range (hereinafter, referred to as an electric range) such as a cooktop.

The electric range may include a case 2 for forming an external appearance. The electric heater 1 may be disposed at an upper portion of the cabinet 2. The upper surface of the case 2 may be opened, and the electric heater 1 may be disposed on the upper surface of the case 2.

The electric range may include: an input unit 3 for operating the electric cooker; and a display 4 for displaying various information such as information of the electric cooker. Also, the electric range may further include a power supply part 5 which is connected to the electric heater 1 and applies current to the electric heater 1. The electric cooker may further include a control part 6 that controls the power supply part 5 and the display 4 according to an input of the input part 3.

The electric heater 1 may be provided to the case 2 in such a manner that an upper surface thereof is exposed to the outside. A heating target heated by the electric range may be placed on an upper surface of the electric heater 1, and the upper surface of the electric heater 1 may be a heating target seating surface for seating the heating target.

Fig. 3 is a sectional view showing an electric heater according to an embodiment of the present invention.

The electric heater 1 may include: a substrate 10; and a plurality of planar heating elements 100 formed on one surface of substrate 10.

The substrate 10 may be an insulating substrate capable of forming a conductor pattern on a surface thereof. The upper surface of the substrate 10 may be a heating target seating surface 13 for seating a heating target. The lower surface of substrate 10 may be a planar heat-generating body forming surface 14 for forming planar heat-generating body 100.

The substrate 10 may be configured as a base 11 entirely formed of an insulating material, and may include: a base 11 made of an insulating material or a non-insulating material; and an insulating layer 12 formed on one surface of the base 11.

The base 11 may be made of glass, and the insulating layer 12 may be formed on the lower surface of the glass by a method such as coating or printing.

The planar heating element 100 may be formed directly on one surface of the insulating base 11 or may be formed on the insulating layer 12.

The base 11 may be formed in a plate shape for placing a heating target, and may be formed in a container shape in which the heating target can be accommodated.

The insulating layer 12 may be formed on the lower surface of the base 11. The insulating layer 12 may be formed on the entire lower surface of the base 11, or may be formed only in a partial region of the lower surface of the base 11. Insulating layer 12 may be formed only in the region where sheet heating element 100 is formed. The insulating layer 12 may constitute the entire lower surface of the substrate 10, or may constitute a part of the lower surface of the substrate 10.

Sheet heating element 100 may be formed on lower surface 14 of insulating layer 12. The size of planar heating element 100 may be smaller than the size of substrate 10, and the lower surface of substrate 10 may include: a heating region H for forming sheet heating element 100; and a non-heated zone UH located at the periphery of the heated zone H.

The electric heater 1 may further include a coating layer 18 for surrounding the planar heat-generating body 100. Coating layer 18 may be formed of an electrically insulating material and may protect sheet heating element 100.

The substrate 10 of the present embodiment may be made of a flexible material, for example, a flexible insulating film (film). In this case, the electric heater 1 may be a flexible planar heater. Of course, such a flexible planar heater may be attached to a member for placing a heating target and heat the heating target, like the upper plate of the electric range.

FIG. 4 is a plan view showing a single sheet heating element according to an embodiment of the present invention, and FIGS. 5A and 5B are cross-sectional views taken along line A-A 'and line B-B' of FIG. 4.

As shown in fig. 4, the single-type planar heat generating element according to the present invention is a planar heat generating element in which only a first planar heat generating element 100 including one heat ray is formed, the first planar heat generating element 100 including: a pattern portion 110 in which heat lines are arranged in a predetermined shape; and an electrode part 120 supplying current to the pattern part 110.

The pattern portion 110 is formed of heat generating portions in which heat lines are compactly arranged in a circular finite area, connects the outermost start point and the outermost end point along various paths, and is formed in a shape that is bilaterally symmetrical with respect to the center of the pattern portion 110 as shown in fig. 4.

According to an embodiment, the pattern part 110 may include: a plurality of circular arc-shaped rails 111 spaced apart from each other and extending outward from the center of the pattern portion 110; and a plurality of bridges 112 connecting the plurality of rails 111 in series.

In this case, the area of the pattern part 110 and the length of the heat ray constituting the pattern part 110 may be set in proportion to the required power.

The plurality of electrodes 120 are formed of a non-heat generating portion having a relatively low heat generation amount compared to the pattern portion 110, and include an anode electrode 121 for flowing a current and a cathode electrode 122 for flowing a current, and the anode electrode 121 and the cathode electrode 122 may be disposed outside the pattern portion 110 so as to be spaced apart from each other by a predetermined gap.

The anode electrode 121 is a portion extending from the start point of the pattern portion 110 and connected to an external input terminal, and the cathode electrode 122 is a portion extending from the end point of the pattern portion 110 and connected to an external output terminal.

When an electric current is supplied to the single-type planar heating element configured as described above, the electric current flows through the anode electrode 121, the pattern portion 110, and the cathode electrode 122 in this order.

At this time, the pattern part 110 functions as a kind of resistance and generates heat to 600 ℃ or more, thereby cooking the heating target placed on the pattern part 110.

However, the electrode portion 120 is preferably formed to generate heat to 200 ℃ or less, or to generate little heat.

Of course, in order to greatly reduce the resistance of the electrode part 120, the width of the electrode part 120 may be formed to be larger than the width of the pattern part 110.

However, since the area in which the electrode part 120 can be formed is limited, the thickness of the electrode part 120 is preferably formed to be greater than the thickness of the pattern part 110.

As shown in fig. 5A, the thickness T2 of the anode electrode 121 is formed to be greater than the thickness T1 of the pattern part side rail 111, and the thickness of the anode electrode 121 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the rail 111, but is not limited thereto.

Of course, the cathode electrode 122 may be formed to have a thickness greater than the thickness T1 of the track 111.

On the other hand, the rail 111 is formed in a gently curved shape, that is, a curvature radius is formed to be relatively large; and the bridge 112 is formed in a sharply curved shape, i.e., a radius of curvature is formed to be relatively small.

At this time, the difference in density of the current flowing inside and outside the bridge 112 is large, and thus the bridge 112 excessively generates local heat as compared to the rail 111.

Therefore, in order to prevent the bridge 112 from generating local heat, the resistance of the bridge 112 is preferably made small.

Of course, the electrode portion 120 may be formed to have a large width so as to reduce the resistance of the bridge 112, but in consideration of a limited area, it is preferable to increase the thickness thereof.

As shown in fig. 5B, the thickness T3 of the bridge 112 is formed to be greater than the thickness T1 of the rail 111, and the thickness T3 of the bridge 112 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the rail 111, but is not limited thereto.

In order to produce a single-type planar heating element configured as described above, it can be produced by printing a conductive material in the shape of a track, a bridge, and an electrode portion on the surface of a substrate, drying the printed conductive material, then printing the same conductive material or a different conductive material in the shape of a bridge and an electrode portion on the surface of a substrate again, and firing the printed conductive material.

The printing process may be performed in various ways such as a spray process, but is not limited thereto.

In this way, a planar heating element in which the bridge and the electrode portion are formed thicker than the rail can be easily produced, and not only can the electrode portion be formed as a non-heating portion, but also local heating of the bridge can be eliminated.

FIG. 6 is a plan view showing a double sheet heating element according to an embodiment of the present invention, and FIGS. 7A and 7B are cross-sectional views taken along line C-C 'and line D-D' of FIG. 6.

As shown in fig. 6, the double sheet heating element of the present invention includes: an inner planar heating element 100 located at the center of the same plane; and an outer sheet heating element 200 disposed so as to surround the inner sheet heating element 100.

The inner surface heating element 100 includes: inner pattern portions 110 arranged in a predetermined shape; an inner electrode part 120 for supplying current to the inner pattern part 110; and an inner side connector 130 for connecting the inner pattern part 110 and the inner electrode part 120.

The inner pattern portion 110 and the inner electrode portion 120 are configured in the same manner as the pattern portion and the electrode portion described in the single planar heating element, and thus detailed description thereof will be omitted.

The inner connector 130 is an auxiliary heat generating portion that can generate heat at the same temperature as the inner pattern portion 110, and is a portion extending from the start point and the end point of the inner pattern portion 110 to the inner electrode portion 120.

The inner connector 130 may be positioned between at least one pair of outer bridges 212, which are opening portions provided at one side of the outer pattern portion 210, which will be described later.

One inside connector 131 connects the start point of the inside pattern part 110 and the inside anode electrode 121, and the other inside connector 132 connects the end point of the inside pattern part 110 and the inside cathode electrode 122.

Since the inside connectors 131 and 132 are directly connected to the inside anode electrode 121 and the inside cathode electrode 122, a large potential difference may be generated between the inside connectors 131 and 132 while a current flows, and short-circuiting of the inside connectors 131 and 132 may occur.

Therefore, in order to prevent the short circuit between the inside connectors 131, 132, it is necessary to dispose the inside connectors 131, 132 away from each other so that the both maintain the insulation gap, and the inside connectors 131, 132 may be disposed in parallel with each other so that the interval between the both maintains at least 20mm or more, but not limited thereto.

The outer surface heating element 200 includes: an outer pattern portion 210 arranged outside the inner pattern portion 110 in a predetermined shape; and an outer electrode part 220 connected to the outer pattern part 210.

The outer pattern portion 210 is formed of heat generating portions which are compactly arranged in a ring-shaped limited area surrounding the outer side of the inner pattern portion 110, are connected between a start point and an end point located at the innermost side along various paths, and are formed in a bilaterally symmetrical shape.

According to an embodiment, the outer pattern part 210 may also include a plurality of outer rails 211 and a plurality of outer bridges 212, like the inner pattern part 110.

Further, a part of the inner connectors 131 and 132 may be positioned between the outer bridges 212, which are openings provided on one side of the outer pattern portion 210.

The outer electrode portion 220 includes a non-heat generating portion extending from the start point and the end point of the outer pattern portion 210, and includes an outer anode electrode 221 and an outer cathode electrode 222 horizontally arranged.

Of course, the outer electrode portion 220 may be positioned in the same direction as the inner electrode portion 120 so that current is supplied to the inner sheet heating element 100 and the outer sheet heating element 200 through one power supply portion.

When an electric current is supplied to the outer sheet heating element 200 configured as described above, the electric current flows through the outer anode electrode 221, the outer pattern portion 210, and the outer cathode electrode 222 in this order, similarly to the inner sheet heating element.

In this case, the outer pattern portion 210 is formed of a heat generating portion that generates heat to 600 ℃ or higher, and the outer electrode portion 220 is formed as a non-heat generating portion that generates heat to 200 ℃ or lower or hardly generates heat.

However, when considering the limited area of the outer electrode part 220 that can be formed, it is preferable that the outer electrode part 220 is formed thicker than the outer pattern part 210, so that the resistance of the outer electrode part 220 can be greatly reduced.

As shown in fig. 7A, the thickness T2 of the outer anode electrode 221 may be formed to be greater than the thickness T1 of the outer rail 211, and the thickness of the outer anode electrode 221 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the outer rail 211, but is not limited thereto.

Of course, the outer cathode electrode 222 may be formed to have a thickness greater than the thickness T1 of the outer track 221.

In addition, the outer bridge 212 is formed in an excessively curved shape compared to the outer rail 211, and thus local heat generation occurs due to a current density difference between the inner side and the outer side. Therefore, it is preferable to greatly reduce the resistance of the outer bridge 212 to prevent local heat generation.

As shown in FIG. 7B, the thickness T3 of the outer bridge 212 may be formed to be greater than the thickness T1 of the outer rail 211, and the thickness T3 of the outer bridge 212 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the outer rail 211, but is not limited thereto.

The outer planar heating element configured as described above may be formed by printing at least twice or more steps to form the outer bridge and the outer electrode portion thicker than the outer rail, as in the case of the single planar heating element.

FIG. 8 is a plan view showing a triple planar heat-generating element according to an embodiment of the present invention, and FIGS. 9A and 9B are cross-sectional views taken along lines E-E 'and F-F' in FIG. 8.

As shown in fig. 8, the triple planar heat generating element of the present invention may be composed of a first planar heat generating element 100 positioned at the center of the same plane, a second planar heat generating element 200 arranged so as to surround the first planar heat generating element 100, and a third planar heat generating element 300 arranged so as to surround the second planar heat generating element 200.

The first planar heating element 100 is composed of a first pattern portion 110, a first electrode portion 120, and a first connector 130, and is configured similarly to the inner pattern portion, the inner electrode portion, and the inner connector described in the description of the double-type inner planar heating element, and therefore, detailed description thereof is omitted.

The second planar heating element 200 is composed of a second pattern portion 210, a second electrode portion 220, and a second connector 230, and is configured similarly to the outer pattern portion and the outer electrode portion described in the double outer planar heating element, and therefore, a detailed description thereof is omitted.

However, the second connector 230 is formed as an auxiliary heat generating portion that can generate heat at the same temperature as the second pattern portion 210, and the second connector 230 is a portion extending from the start point and the end point of the second pattern portion 210 to the second electrode portion 220 and is disposed outside the first connector 130.

Therefore, the first connector 130 and the second connector 230 may be located at the opening portions provided at one side of the second pattern portion 210 and the third pattern portion 310, which will be described later, that is, between at least one pair of the second bridges 212 and one pair of the third bridges 312.

One second connector 231 connects the start point of the second pattern part 210 and the second anode electrode 221, and the other second connector 232 connects the end point of the second pattern part 210 and the second cathode electrode 222.

The third surface heating element 300 includes: a third pattern part 310 arranged outside the second pattern part 210 in a predetermined shape; and a third electrode part 320 connected to the third pattern part 310.

The third pattern part 310 is formed in a ring-shaped heat generating part of a limited area surrounding the outside of the second pattern part 210 in a compact arrangement, and is formed in a left-right symmetrical shape by connecting the start point and the end point located at the outermost side along various paths.

According to an embodiment, the third pattern part 310 may be formed of a plurality of third tracks 311 and a plurality of third bridges 312, as in the second pattern part 210.

The third electrode portion 320 is a non-heat generating portion extending from the start point and the end point of the third pattern portion 310, and is composed of a third anode electrode 321 and a third cathode electrode 322 which are horizontally arranged.

Of course, the third electrode portion 320 is located in the opposite direction to the first electrode portion 120 and the second electrode portion 220 so that current is supplied to the first planar heat-generating element 100 and the second planar heat-generating element 200 via one power supply portion and current is supplied to the third planar heat-generating element 300 via the other power supply portion.

When current is supplied to the third surface-shaped heat-generating element 300 configured as described above, the current flows through the third anode electrode 321, the third pattern part 310, and the third cathode electrode 322 in this order.

Similarly, the third pattern part 310 is formed as a heat generating part that generates heat to 600 ℃ or higher, and the third electrode part 320 is formed as a non-heat generating part that generates heat to 200 ℃ or lower or hardly generates heat.

Therefore, similarly to the first electrode portion 120 and the second electrode portion 220, the resistance of the third electrode portion 320 is preferably significantly reduced.

As shown in fig. 9A, the thickness T2 of the third anode electrode 321 is formed to be greater than the thickness T1 of the third track 311, and the thickness T2 of the third anode electrode 321 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the third track 311, but is not limited thereto.

Of course, the third cathode electrode 322 may be formed to have a thickness greater than that of the third track 311.

Similarly to the first bridge 112 and the second bridge 212, it is also preferable to reduce the resistance of the third bridge 312 to a large extent so as to eliminate local heat generation due to the difference in current density.

As shown in fig. 9B, the thickness T3 of the third bridge 312 is formed to be greater than the thickness T1 of the third track 311, and the thickness T3 of the third bridge 312 may be formed in the range of 1.3 to 2.0 times the thickness T1 of the third track 311, but is not limited thereto.

The third surface-shaped heat generating element configured as described above can also be formed into the third bridge and the third electrode portion thicker than the third track by a process of printing at least twice or more, similarly to the double-type first surface-shaped heat generating element and the second surface-shaped heat generating element.