KR100664349B1 - Led board for illumination and illumination unit including the board - Google Patents

Abstract

An LED(Light Emitting Diode) board for illumination and an illumination unit including the same are provided to prevent the product from being damaged by a heat and a stress incurrence by adopting a Graphate sheet instead of a metal PCB. In an LED board for illumination, a Graphate sheet(100) diffuses a heat. A nonconductor layer(200) is laminated on an upper surface of the Graphate sheet(100). A conductive thin layer(300) formed on an upper surface of the nonconductor layer(200) includes a circuit supplying an electrical driving signal to an LED(400). A reflection layer is coated on an upper surface of the conductive thin layer.

Description

LED board for illumination and lighting unit including the same {LED board for illumination and illumination unit including the board}

1 is a cross-sectional view of an LED substrate for illumination according to an example.

2 is a cross-sectional view of an LED substrate for illumination according to another example.

3 is a cross-sectional view of the LED substrate for illumination according to the present invention.

4 is a plan view of the lighting unit to which the LED substrate for illumination of FIG. 3 is applied.

5 is a cross-sectional view along the line A-A 'of FIG.

6 is a plan view illustrating an insulator layer on which a conductive thin film is formed, according to an exemplary embodiment.

7 is a diagram illustrating a structure of a backlight unit according to an embodiment.

8 is a cross-sectional view taken along the line A-A 'of FIG. 4 according to another embodiment.

9 is a perspective view of the upper graphite sheet applied in FIG. 8 according to one embodiment.

10 is a diagram illustrating a structure of a backlight unit according to another embodiment.

11 through 13 are cross-sectional views taken along line B-B 'of another embodiment.

14 is a plan view showing an integrally formed graphite sheet according to an embodiment.

15 is a cross-sectional view taken along line C-C 'of FIG.

16 illustrates various structures of a metal network.

FIG. 17 illustrates a graphite sheet including a metal network therein; FIG.

<Explanation of symbols for the main parts of the drawings>

100: graphite sheet 150: metal mesh

200: non-conductive layer 300: conductive thin film

400: LED 500: Casing

600: reflective layer 700: upper graphite sheet

800: reflective layer

The present invention relates to an LED substrate for lighting and a lighting unit including the same, and more particularly, to a technology for efficiently dissipating heat generated by an LED (LED).

There are various displays of digital and media devices such as CRT, PDP, LCD, organic EL, etc., but TFT-LCD is emerging as one of the most important display types. TFT-LCDs can be largely divided into three units. The first is a panel in which liquid crystal is injected between the substrate and the second, and the second is a printed circuit board (PCB) to which a driver LSI and various circuit elements are attached to drive the panel. And as can be seen in the expression of liquid crystal, since the TFT-LCD can not emit light by itself, an external light source is essential. Therefore, it is divided into a chassis structure including a backlight that provides a light source. Hereinafter, a backlight unit related to the present invention will be described.

Light sources used in the backlight unit include fluorescent lamps, LED lamps and the like. Cold Cathode Fluorescent Lamp (CCFL: Cole Cathode Flourscent Lamp) is a typical light source for backlight unit. It is adopted as a light source of the backlight unit. However, the LED lamp of the backlight unit has a big disadvantage that a higher temperature than the fluorescent lamp. The power consumption per LED lamp is about 1W, and more than 70% of heat is generated at 1W power consumption. Typically, the number of LED lamps used in the backlight unit of a 30-inch TFT-LCD is about 200, and the heat generated is about 140W. The heat generated here increases the temperature inside the backlight unit, affecting various components constituting the backlight unit. This may cause deformation of the product, heat upstream of the backlight unit may cause a difference in the vertical temperature of the backlight unit may cause stress, and this problem may lead to the loss of the backlight function.

Therefore, in a backlight unit employing an LED lamp as a light source, there is a need for a method of effectively treating heat generated inside the backlight unit to lower the internal temperature and reduce an internal temperature deviation. Cooling, which is generally used in electronic products and communication equipment, often solves heat problems by using heat sinks, bottom pipes, and fans. In the cooling of the backlight unit, if a cooling device is used using a heat sink generally applied to electronic products or communication equipment, the volume of the cooling device becomes large due to the structure of the heat sink. Therefore, since it is inappropriate to adopt a backlight unit that requires slimming, many cooling devices that are modularized using heat transfer media such as heat pipes are usually employed. However, the use of heatpipes results in significantly higher costs, and their volume is also undesirable to satisfy slimming.

Another problem that impedes heat dissipation is that the substrate applied to the backlight unit is metal. Due to the high material cost of the metal PCB and the limitations of heat transfer due to the physical properties of the metal PCB (hard and flatness cannot be maintained), high manufacturing costs, temperature deviations inside the backlight unit, and heat dissipation are caused in the manufacturing of the backlight unit. Are still present, and these problems will become more and more serious in the future trend of larger LCDs. In addition, the back light unit structure is complicated by the use of metal PCB, the manufacturing process is also complicated.

Meanwhile, Korean Patent Application No. 2005-36789, filed on October 14, 2004 and published on April 20, 2005, by an applicant named 'Advanced Energy Technology Incorporated' discloses efficient heat generation from a display device. A technique of using a graphite sheet to diffuse and radiate heat is disclosed. Graphite sheets have anisotropic properties that are effective for heat transfer in the plane direction, and utilize the fact that such properties are suitable for diffusing heat generated in display devices requiring slimming. However, the prior art is limited to a technique of applying heat to the heat dissipation by applying a graphite sheet to a light emitting display device capable of self-emission such as a plasma display panel (PDP). Specifically, the prior art is limited to the light emitting display device having a surface area larger than the surface area of the discharge cell portion facing the back of the light emitting display device and including one or more sheets of compressed particles of exfoliated graphite.

On the other hand, the applicant has focused on the heat dissipation problem of a display device that requires illumination, such as a TFT-LCD that cannot emit light. In the conventional display device such as TFT-LCD, a cold cathode fluorescent lamp (CCFL) is mainly used as a light source, so there is no problem of heat dissipation. However, as the LED lamp is replaced, the heat dissipation problem as described above becomes essential. Accordingly, the present applicant has sought a technical method of applying a graphite sheet to solve a heat dissipation problem in a display device such as a TFT-LCD which cannot emit light, as well as various lighting means using LEDs such as a lamp or an advertisement board.

The present invention is derived from this background, it is an object of the present invention to provide an LED substrate and a lighting unit for lighting that can increase the heat radiation efficiency by adding a new heat radiation means.

It is also an object of the present invention to provide an LED substrate and a lighting unit for lighting having a simple structure.

It is also an object of the present invention to provide an LED substrate for lighting and a lighting unit that can be manufactured at low cost.

It also aims to simplify the assembly and process.

As a technical solution for solving the above-described problems, a method of attaching a graphite sheet to the lower portion of the backlight unit may be considered. FIG. 1 is a cross-sectional view of such a structure. As shown, the graphite sheet 12 is attached to the bottom of the bottom chassis of the casing 10 of the backlight unit. Since the graphite sheet 12 is excellent in heat conductivity and heat transfer sealing property, the graphite sheet 12 provides excellent sealing property even when directly in contact with the casing 10. The metal PCB 14 is stacked on the casing 10, and an LED 16 is arranged thereon. In addition, since the metal PCB 14 and the casing 10 are bonded between metals, a rubber pad GAP 18 having excellent thermal conductivity is disposed therebetween for sealing the heat transfer. By bonding the graphite sheet 12 to the lower portion of the casing 10 as described above, the backlight unit can be manufactured in a slim form, and the heat dissipation efficiency can be increased. However, since the graphite sheet 12 is added to the existing backlight unit itself, the structure becomes more complicated, and a scratch problem occurs during the manufacturing process because the graphite sheet 12 is exposed to the outside.

As a more improved solution to solve this problem, a method of placing the graphite sheet inside the backlight unit may be considered. 2 is a cross sectional view of such an improved structure. As shown, a graphite sheet 32 is stacked on the bottom sash of the casing 30 of the backlight unit. The metal PCB 34 is stacked on the graphite sheet 32, and an LED 36 is arranged thereon. Since the graphite sheet 32 is more flexible than metal, a gap pad is not required between the metal PCB 34 and the graphite sheet 32. By placing the graphite sheet 32 inside the backlight unit as described above, the heat dissipation efficiency can be improved while solving the above-described scratch problem. In addition, no gappad is required, which simplifies the structure compared to the previous.

However, there are still problems such as high manufacturing cost and complicated structure due to the use of metal PCB. Accordingly, the present applicant has the idea of eliminating the metal PCB and using the graphite sheet itself as a substrate for solving the problem, and thus, the present invention has been derived.

The lighting unit according to an aspect of the present invention for achieving the above-mentioned object derived through this process is a casing,

A plurality of LED substrates for illumination including a graphite sheet that contacts the inner surface of the casing to diffuse heat, an insulator layer stacked on the graphite sheet, and a conductive thin film formed on the insulator layer,

It includes a plurality of LED (LED) arranged side by side to receive the electric drive signal from the conductive thin film.

As described above, the lighting unit according to the present invention employs graphite sheets having higher thermal conductivity, lower cost, and flexibility than metal PCBs, thereby more efficiently spreading heat generated by LEDs. The heat dissipation can prevent direct damage to the product due to heat and damage to the product caused by stress, and can be manufactured at a cheaper price (1/2 price compared to the price of metal in general), as well as flexibility ( Due to the nature of flexible), even if directly attached to the casing of the metal material provides a sufficient sealing effect, the heat radiation efficiency is very good. In other words, since the graphite sheet is more flexible than metal, a gap pad is not required between the graphite sheet 32 and the casing 30. However, the present invention is not limited thereto, and of course, a similar type of gap pad may be added to improve the adhesion. In addition, since the assembly process is simple, the number of processes can be reduced to increase the production rate.

The lighting unit according to an additional aspect of the present invention further includes a reflective layer coated on the conductive thin film.

As described above, the lighting unit according to the present invention may increase the luminance, that is, display brightness by re-reflecting the light reflected from the configuration to be transmitted from the LED lamp to the LCD panel such as the light guide plate or the diffusion plate by employing the reflective layer.

The lighting unit according to an additional aspect of the present invention further includes an upper graphite sheet stacked on top of the conductive thin film, except for the arrangement position of the plurality of LEDs.

As described above, the lighting unit according to the present invention can dissipate heat by spreading heat more effectively by employing a graphite sheet not only at the bottom but also at the top.

The lighting unit according to an additional aspect of the present invention is characterized in that the graphite sheet in contact with the upper surface in the casing is thicker or denser than the graphite sheet in contact with the lower surface thereof.

As such, the lighting unit according to the present invention may minimize the difference in temperature distribution between the upper and lower portions by varying the thickness or density of the graphite sheet, which is the base of the plurality of LED substrates in the casing, thereby preventing the occurrence of stress. Can be.

The lighting unit according to a further aspect of the invention, the graphite comprises a metal reticle therein.

As described above, the lighting unit according to the present invention has an isotropic property by including the metal reticular body in the graphite, and thus heat dissipation can be well performed in the thickness direction as well as in the surface direction, thereby enabling more effective heat dissipation.

The foregoing and further aspects of the present invention will become more apparent through the preferred embodiments described with reference to the accompanying drawings. Hereinafter, the present invention will be described in detail to enable those skilled in the art to easily understand and reproduce the present invention.

3 is a cross-sectional view of the LED substrate for illumination according to the present invention. As shown, the LED substrate for illumination is formed of a graphite sheet 100 for diffusing heat, an insulator layer 200 stacked on the graphite sheet 100, and formed on the insulator layer 200 to be electrically connected to an LED. And a conductive thin film 300 constituting a circuit for supplying a typical driving signal. Graphite sheet (100) is a pure graphite product processed by acid treatment and high temperature treatment of purified natural impression graphite without any additives, and has the unique characteristics of graphite such as heat resistance and chemical resistance. ) And excellent compressive resilience. As is known, the graphite sheet 100 has a layer structure in which carbon has a layer structure, and molecules in each layer plane direction are strongly bonded by covalent bonds, and have anisotropic property in which heat is diffused well in the plane direction. The nonconductive layer 200 of the film film is laminated on the graphite sheet 100, and the conductive thin film 300 is formed on the nonconductive layer 200. The conductive thin film 300 is patterned to form a conductive pattern, and supplies an electric driving signal to the LED through the formed conductive pattern. In addition, since the non-conductive layer 200 has electrical conductivity, graphite prevents a short with the conductive pattern formed on the conductive thin film 300.

4 is a plan view of a lighting unit to which the LED board for illumination of FIG. 3 is applied. Multiple illumination LED substrates are bonded to the bottom chassis bottom surface in the casing 500. And it can be seen that a plurality of LED 400 elements are arranged side by side on each LED substrate for illumination. Each LED board for illumination is also electrically connected through a jump wire. In addition, the casing 500 and each lighting LED substrate may be fixedly coupled to the bolt-nut (circled portion of FIG. 4).

5 is a cross-sectional view along the line A-A 'of FIG. The graphite sheet 100 is stacked on the bottom chassis in the casing 500. Due to the flexible nature of the graphite sheet 100, it provides an excellent sealing effect even when directly in contact with a bottom chassis without an intermediate such as a rubber pad. As described above, the insulator layer 200 of the film film is stacked on the graphite sheet 100, and the conductive thin film 300 is formed on the insulator layer 200. FIG. 6 illustrates a plan view in which the conductive thin film 300 is formed on the non-conductive layer 200 and the non-conductive layer 200, and the LEDs 400 have irregularities between the conductive patterns of the conductive thin film 300. The parts are soldered and electrically connected across the two electrode patterns and arranged side by side.

The biggest feature of this structure is that the graphite sheet 100 is used as a substrate without using a separate metal PCB. An insulator layer and a patterned conductive thin film are formed on the graphite sheet 100 to supply an electric driving signal to the LED 400, and the graphite sheet 100 is used as a heat dissipation means without providing a separate heat dissipation means. Will also use. In general, the material used for metal PCB is AL metal, silicon steel sheet, galvanized steel sheet, etc., which have high thermal conductivity, but the thermal conductivity is in the range of 100W / mk to 240W / mk, and the material cost is also quite expensive. . However, the thermal conductivity of the expanded graphite sheet 100 rolled expanded graphite employed in accordance with an advantageous aspect of the present invention is higher than the metal in the range of 220W / mk ~ 370W / mk, the price is cheap (usually 1/2 price compared to the metal price) ), It is flexible. In the present invention, the LED 400 can be arrayed on the graphite sheet 100 so that heat is diffused in the plane direction so that the temperature is about 3 to 4 ° C lower than when a metal PCB is used. Not only can the efficiency be achieved, but also the manufacturing of the LED board for a low cost illumination is made possible. In addition, since the assembly process is simple, the number of processes can be reduced to increase the production rate.

Furthermore, the LED substrate for illumination further includes a reflective layer 600. As shown in the structure of the backlight unit illustrated in FIG. 7, the reflective layer 600 is coated on the conductive thin film 300. And the role is that some of the light irradiated from the LED 400 to the LCD panel 810, Prism Sheet (Prism Sheet) 820 / Diffuser Sheet (830) / Light Guide Panel (840) It is intended to increase the luminance by rereflecting the light reflected from the / Reflector Sheet (850) side. As described above, when the lighting unit including the reflective layer 600 according to the present invention is adopted for a flat panel display panel, the lighting unit transmits light emitted from the LED 400 such as a light guide plate / diffusion sheet to a LCD panel. If this is not possible, the reflected light may be reflected again to increase luminance, that is, display brightness.

8 is a cross-sectional view along the line A-A 'of another embodiment of the present invention. As can be seen from the figure, the difference from FIG. 5 is that it further comprises an upper graphite sheet 700. The shape of the upper graphite sheet 700 according to one embodiment is shown in perspective view in FIG. 9. The hole formed in the upper graphite sheet 700 is a place where the LED 400 is located. The upper graphite sheet 700 diffuses heat generated by the LED 400 similarly to the graphite sheet 100. In this way, the graphite sheet is applied not only to the lower portion but also to the upper portion to more effectively spread heat and radiate heat. That is, the heat dissipation efficiency can be obtained that the temperature is about 4 ~ 5 ° C lower than when using a metal PCB.

Furthermore, the LED substrate for illumination further includes a reflective layer 800. As shown in the structure of the backlight unit illustrated in FIG. 10, the reflective layer 800 is coated on the upper graphite sheet 700. And the role is that some of the light irradiated from the LED 400 to the LCD panel 810, Prism Sheet (Prism Sheet) 820 / Diffuser Sheet (830) / Light Guide Panel (840) It is intended to increase the luminance by rereflecting the light reflected from the / Reflector Sheet (850) side. As described above, when the lighting unit including the reflective layer 800 according to the present invention is adopted for a flat panel display panel, the lighting unit transmits light emitted from the LED 400 such as a light guide plate / diffusion sheet to a LCD panel. If this is not possible, the reflected light may be reflected again to increase luminance, that is, display brightness.

11 to 13 are cross-sectional views taken along line B-B 'of FIG. 4 according to different embodiments. 11 to 13, it can be seen that the thickness of each graphite sheet 100 in contact with the bottom chassis in the casing is thicker as it is in contact with the top surface of the bottom chassis. The reason for varying the thickness of each graphite sheet 100 as described above is to prevent the occurrence of temperature deviation. In any lighting unit, the upper temperature tends to be distributed higher than the lower temperature because of the convection of heat in the space where the high heat is collected at the top of the space and the low heat is collected at the bottom of the space. Therefore, the thickness of the graphite sheet 100 in contact with the upper surface (located on the upper side) of the casing is thicker than the thickness of the graphite sheet 100 in contact with the lower surface (located on the lower surface).

11, however, since the heights of the LEDs 400 are different, luminance deviation may occur. Therefore, when the thickness of the graphite sheet 100 is changed, it is preferable to incline the bottom chassis of the casing 500 as shown in FIG. 12 or to have a step shape as shown in FIG. 13. However, the present invention is not limited to this form, and a form capable of keeping the height of the LED constant is sufficient. And although not shown, it is obvious that the upper graphite sheet 700 can also be applied to a different thickness. By varying the thickness of the graphite sheet in this way it is possible to minimize the difference in the temperature distribution in the lighting unit to prevent damage caused by stress.

In another embodiment, the density of the graphite sheet 100 may be different without changing the thickness of the graphite sheet 100 as described above. That is, the density of the graphite sheet 100 in contact with the upper surface of the casing 500 is higher than the density of the graphite sheet 100 in contact with the lower surface. Density control of the graphite sheet 100 at each relative position in the casing 500 may be achieved by varying the degree of compression of each graphite sheet 100. That is, by increasing the degree of compression so that the graphite fiber itself becomes more dense, the density of the graphite sheet 100 in contact with the upper surface of the casing 500 may be higher than the density of the graphite sheet 100 in contact with the lower surface. It is. Although not shown, it is obvious that the upper graphite sheet 700 may be applied with a different density. As such, by varying the density of the graphite sheet, it is possible to minimize the difference in temperature distribution in the lighting unit, thereby preventing damage caused by stress.

14 is a plan view illustrating an integrally formed graphite sheet according to an embodiment, and FIG. 15 is a cross-sectional view taken along line C-C 'of FIG. 14. Unlike FIG. 11, the graphite sheet 100 is integrally formed. By integrating the graphite sheet 100, as shown in FIGS. 11 to 13, a jump wire for electrically connecting each LED board for illumination is not required. As a result, manufacturing costs can be further lowered.

Although not illustrated in FIG. 15, the reflective layer 100 as shown in FIG. 7 is further coated on the conductive thin film 300 formed on the non-conductive layer 200 stacked on the integrally formed graphite 100 sheet. Can produce the same effect as Furthermore, the portion of the integrated graphite sheet 100 that contacts the upper surface of the bottom chassis in the casing 500 may be different from the portion of the graphite sheet 100 that is in contact with the lower surface, or the density may be different. The reason for this is to prevent the occurrence of stress by preventing the temperature variation as described above. When the thickness of the integrated graphite sheet 100 is changed, it is preferable to form the casing 500 as shown in FIG. 12 or FIG. 13. The reason is as described above. In addition, the upper graphite sheet 700 may be integrated, and the reflective layer 100 may be coated on the reflective layer 100 as shown in FIG. 10, and the thickness or density may be changed as in the integrated graphite sheet 100.

According to an additional aspect of the present invention, the graphite sheet 100 may include a metal network 150 therein. As shown in FIG. 16, the metal mesh 150 may have a net-shaped sheet formed by weaving metal wires, and may have a sheet-shaped sheet formed by drilling a plurality of holes in a metal plate, and a plurality of upper and lower metal plates. It may have a sheet shape having a shape of irregularities. As the material of the metal network 150, it is preferable to have a high thermal conductivity such as copper, stainless steel, platinum, aluminum, titanium, nickel, or the like. Since the metal mesh 150 is excellent in flexibility, even if included in the graphite sheet 115, the flexibility of the graphite sheet 100 is not degraded. The manufacturing method of the graphite sheet 100 including the metal network 150 therein is preferably made of a rolling method with a metal network therebetween as shown in FIG. 17.

The reason for placing the metal network 150 inside the graphite sheet 100 is to change the anisotropic characteristic of the graphite sheet 100 to further increase the heat dissipation effect. Since the graphite sheet 100 having anisotropic property diffuses heat generated from the LED 400 in the plane direction but does not diffuse well in the thickness direction, the graphite sheet 100 preferably includes the metal mesh 150 in the graphite sheet 100. To change the property to isotropic. Accordingly, the graphite sheet 100 can diffuse heat well in the thickness direction as well as the surface direction, thereby providing an advantage of further increasing the heat dissipation effect. Since the graphite sheet itself is a known technical configuration, detailed description thereof will be omitted.

As described above, the present invention employs a graphite sheet having higher thermal conductivity, lower cost, and flexibility than metal PCB, thereby more efficiently spreading and radiating heat generated by LEDs. It can be used to prevent direct damage to the product by heat and damage to the product due to stress, not only to be manufactured at a lower price (1/2 price compared to the price of metal in general), but also to be flexible. Due to its characteristics, even if attached directly to the casing of the metal material, since the sealing effect is sufficiently provided, the heat radiation efficiency is very good. In other words, the adhesion between the casing and the LED (LED) is good, the heat dissipation efficiency is very good. In addition, since the assembly process is simple, the number of processes can be reduced to increase the production rate.

In addition, the present invention by using the graphite sheet in the upper portion as well as the lower portion can be more effectively diffuse heat to radiate heat.

In addition, the present invention can increase the luminance, that is, display brightness by re-reflecting the light reflected from the configuration that is irradiated from the LED (LED) to transmit light, such as a light guide plate, a diffusion sheet, to the LCD panel.

In addition, the present invention can minimize the difference in temperature distribution in the lighting unit, thereby preventing damage caused by stress.

In addition, since the graphite sheet can be integrated to eliminate the jump wire, the manufacturing cost can be further lowered.

In addition, the graphite sheet according to the present invention is able to diffuse heat well in the thickness direction as well as the surface direction, thereby providing an advantage of further increasing the heat dissipation effect.

On the other hand, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. For example, the LED board and the lighting unit for lighting according to the present invention can be applied not only to a backlight for a flat panel but also to a lighting means using various LEDs such as a lighting lamp or a billboard. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (22)

A graphite sheet for diffusing heat; An insulator layer laminated on the graphite sheet; A conductive thin film formed on the insulator layer and constituting a circuit for supplying an electric driving signal to the LED; LED substrate for illumination comprising a. The LED substrate for illumination of claim 1, further comprising a reflective layer coated on the conductive thin film. The method of claim 1, wherein the substrate is: An upper graphite sheet stacked on the conductive thin film, except for an LED position; LED substrate for illumination comprising a further. The method of claim 3, wherein the substrate is: LED substrate for illumination further comprising a reflective layer coated on the upper graphite sheet. The graphite sheet according to claim 1, wherein the graphite sheet is: LED substrate for illumination comprising a metal network inside thereof. Casing; A plurality of LED substrates for illumination including a graphite sheet in contact with an inner surface of the casing, a non-conductive layer stacked on the graphite sheet, and a conductive thin film formed on the non-conductive layer; A plurality of LEDs arranged side by side to receive electric driving signals from the conductive thin film; Lighting unit comprising a. The method of claim 6, wherein each of the LED board for illumination is: Lighting unit further comprises a reflective layer coated on the conductive thin film. The method of claim 6, wherein each of the LED board for illumination is: And an upper graphite sheet stacked on the conductive thin film, except for an arrangement position of the plurality of LEDs. The method of claim 8, wherein each of the LED board for illumination is: The lighting unit further comprises a reflective layer coated on the upper graphite sheet. 7. The lighting unit according to claim 6, wherein the graphite sheet in contact with the upper surface in the casing is thicker or denser than the graphite sheet in contact with the lower surface. The lighting unit according to claim 6, wherein each of the graphite sheets constituting the plurality of lighting LED substrates is integrally formed. The method of claim 11, wherein the LED substrate for illumination is: The upper graphite sheets stacked on the conductive thin film, except for the arrangement position of the plurality of LEDs, further including the upper graphite sheets, wherein the upper graphite sheets positioned on each of the plurality of lighting LED substrates are integrally formed. Lighting unit, characterized in that made in one. The lighting unit of claim 11, further comprising a reflective layer coated on the conductive thin film. 13. The illumination unit of claim 12, further comprising a reflective layer coated on the integrally formed upper graphite sheet. 12. The lighting unit according to claim 11, wherein the integrally formed graphite sheet is thicker or denser than the portion of the casing in contact with the upper surface of the casing in comparison with the portion in contact with the lower surface of the casing. The lighting unit according to claim 12, wherein the integrally formed upper graphite sheet is thicker or denser than a portion of the casing in contact with the upper surface of the casing in comparison with the portion of the upper graphite sheet. The method of claim 6, wherein the graphite sheet is: Lighting unit, characterized in that it comprises a metal network inside. A graphite sheet for diffusing heat; An insulator layer laminated on the graphite sheet; A conductive thin film formed on the insulator layer; A plurality of LEDs arranged side by side to receive electric driving signals from the conductive thin film; Lighting unit comprising a. 19. The device of claim 18, wherein the unit is: A reflective layer coated on the conductive thin film; Lighting unit further comprises. 19. The device of claim 18, wherein the unit is: An upper graphite sheet stacked on the conductive thin film, except for stacking the plurality of LEDs; Lighting unit further comprises. The method of claim 20, wherein the unit is: A reflective layer coated on the upper graphite sheet; Lighting unit further comprises. 22. The method of claim 18, wherein the graphite sheet is: Lighting unit, characterized in that it comprises a metal network inside.

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