KR101059576B1 - LED Board and Lighting Unit for Lighting - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting unit, and more particularly, to a technique for efficiently dissipating heat generated by LEDs.

The lighting unit according to the present invention includes a casing, at least one metal PCB placed on the casing, a plurality of LEDs arranged side by side on the metal PCB to receive an electric drive signal, and emit light to the metal PCB. However, it includes a graphite sheet in contact with each other except the arrangement position of the plurality of LEDs. As described above, the lighting unit according to the present invention has a high thermal conductivity, is inexpensive, and has flexibility to adopt a graphite sheet having high adhesion, so that heat generated by LEDs can be more efficiently diffused and radiated. In addition, since the structure is attached to the LED (LED) which is a heating element, heat dissipation efficiency can be further increased.

LED, heat dissipation, graphite.

Description

LED board for illumination and illumination unit {LED board for illumination and illumination unit}

1 is a plan view of a lighting unit;

2A and 2B are cross-sectional views taken along line A-A 'of FIG. 1 in accordance with an embodiment of the present invention.

3 illustrates a graphite sheet applied to FIG. 1 according to an embodiment.

4 and 5 are sectional views taken along line A-A 'of still another embodiment of the present invention.

6 and 7 are views illustrating a structure of a backlight unit according to different embodiments of the present invention.

8 to 21 are cross-sectional views taken along line A-A 'of still another embodiment of the present invention.

22 illustrates various structures of a metal network.

FIG. 23 is a view showing a graphite sheet including a metal network therein; FIG.

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

100: casing 200: metal PCB

300: LED 400: graphite sheet

500: gap pad 600: reflective layer

700: graphite sheet for the base

800: lower graphite sheet

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting unit, and more particularly, to a technique for efficiently dissipating heat generated by LEDs.

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 of the 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, when a cooling device is used using a heat sink generally applied to electronic products or communication equipment, the volume of the cooling device increases 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.

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 to provide a lighting unit that can increase the heat radiation efficiency by adding a new heat radiation means.

Lighting unit according to an aspect of the present invention for achieving the above object is a casing, at least one metal PCB placed on the casing, a plurality of LEDs are arranged side by side on the metal PCB to receive an electric drive signal to emit light (LEDs) and a graphite sheet in contact with the metal PCB, except for the arrangement position of the plurality of LEDs.

As described above, the lighting unit according to the present invention has a high thermal conductivity, is inexpensive, and has flexibility to adopt a graphite sheet having high adhesion, so that heat generated by LEDs can be more efficiently diffused and radiated. In addition, since the structure is attached to the LED (LED) which is a heating element, heat dissipation efficiency can be further increased.

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.

1 is a plan view of a lighting unit according to an embodiment of the present invention. As shown, a plurality of array bars are bonded to the bottom chassis bottom surface of the casing 100. In addition, it can be seen that a plurality of LED 300 elements are arranged side by side on each array bar. In addition, each of the array bars is electrically connected through a jump wire. The casing 100 and the array bars may be fixedly coupled to the bolt-nut (circled portion of FIG. 1). And although the characteristic aspect according to the present invention is not revealed from the top view, a graphite sheet for efficiently treating the heat generated from the LED 300 which is a heating element is laminated on each array bar. This will be described later with reference to the drawings.

2A and 2B are cross-sectional views taken along line A-A 'of FIG. 1 in accordance with an embodiment of the present invention. As shown, the lighting unit is arranged side by side on the casing 100, the at least one metal PCB 200 on the casing 100, and the metal PCB 200 is supplied with an electric drive signal to emit light A plurality of LEDs 300 and a graphite sheet 400 is in contact with the metal PCB 200, except for the arrangement position of the plurality of LEDs.

At least one metal PCB 200, which is an array bar, is disposed on the bottom chassis of the casing 100. The casing 100 and the metal PCB 200 may be bonded using bolt-nuts. In addition, the plurality of LEDs 300 are arranged side by side on the metal PCB 200 to receive electrical driving signals and emit light. To help dissipate and dissipate heat generated from the LED 300, the material used for the metal PCB 200 is that the AL plate, silicon steel sheet, galvanized steel sheet having a high thermal conductivity is used among the metal desirable.

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 of carbon, and molecules in each layer plane direction are strongly bonded by covalent bonds, and diffuse heat well in the plane direction (high in the range of 220 W / mk to 370 W / mk). Has an thermal conductivity).

A graphite sheet 100 having such characteristics is in contact with the metal PCB circumference 200 as shown in FIG. 2A, or laminated on the metal PCB 200 as shown in FIG. 2B. However, a hole is formed in the graphite sheet 400 at a position corresponding to the arrangement position of the LEDs 300 so that light emitted from the LED 300 is not blocked, and one hole of the graphite sheet in which the hole is formed is formed. An example is shown in FIG. 3. The biggest feature of this structure is that the graphite sheet 400 is located in close proximity to the plurality of LEDs 300 arranged in the metal PCB (200). The graphite sheet 400 having high adhesion due to its flexible characteristics may increase heat dissipation efficiency by diffusing heat generated from the LED 300. Furthermore, the graphite sheet 400 may be integrated as shown in FIG. 4 to further increase heat dissipation efficiency.

Additionally, the lighting unit may further include a gap pad 500 as shown in FIG. 5. Since the casing 100 and the metal PCB 200 are bonded to the metal, the adhesion is poor. Therefore, in order to improve the adhesion, the rubber pads 500 may be placed between the casing 100 and the metal PCB 200 by at least one, thereby increasing the adhesion. Accordingly, it may help to spread the heat generated from the LED 300 is transferred to the bottom.

According to a further aspect of the invention the lighting unit further comprises a reflective layer 600. 6 and 7, the reflective layer 600 is coated on the graphite sheet 400 as shown in the structural example of the backlight unit illustrated in FIG. 6. And the role is that some of the light irradiated from the LED 300 to the LCD panel 910 is a prism sheet (Prism Sheet) 920 / diffuser sheet (930) / light guide panel (940) To reflect the light reflected from the / Reflector Sheet (950) side to increase the brightness. 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, for example, a light guide plate / diffusion sheet is configured to transmit light emitted from the LED 300 to the LCD panel (). Reflected light that is not transmitted from the reflected light can be reflected back to increase brightness, ie, display brightness. In addition, although not shown, as described above, by providing a gap pad 500 between the casing 100 and the metal PCB 200, the adhesion may be improved.

8 and 9 are cross-sectional views taken along line A-A 'of still another embodiment of the present invention. As shown, the lighting unit further includes an integrally formed graphite sheet 700 for contact between the casing 100 and the plurality of metal PCBs 200. Base graphite sheet 700 is also for heat dissipation, like the graphite sheet 400 described above, to efficiently diffuse the heat generated from the LED 300 and transmitted through the metal PCB 200. The flexible nature of the graphite sheet 700 for the base provides a good sealing effect even when directly in contact with the bottom chassis of the casing 100 without an intermediate such as a rubber pad. In other words, since the graphite material is more flexible than metal, a gap pad is not required between the casing 100 and the base graphite sheet 700, the metal PCB 200, and the base graphite sheet 700. However, the present invention is not limited thereto, and a gap pad may be added to improve the adhesion. As described above, the lighting unit according to the present invention may further increase the heat dissipation efficiency according to the addition of the base graphite sheet 700.

10 and 11 are sectional views taken along line A-A 'of still another embodiment of the present invention. As shown, the lighting unit further includes a lower graphite sheet 800 in contact with the bottom of the casing 100. The lower graphite sheet 800 is also for heat dissipation, and to efficiently diffuse heat generated from the LED 300 and transferred through the metal PCB 200 and the casing 100. The flexible nature of the lower graphite sheet 800 provides an excellent sealing effect even when directly in contact with the lower surface of the casing 100 without an intermediate such as a rubber pad. In other words, since the graphite material is more flexible than metal, a gap pad is not required between the casing 100 and the lower graphite sheet 800. However, the present invention is not limited thereto, and a gap pad may be added to improve the adhesion. Although not shown, a gap pad may be added between the metal PCB 200 and the casing 100 to improve adhesion. As described above, the lighting unit according to the present invention may further increase the heat dissipation efficiency according to the addition of the lower graphite sheet 800.

12 to 21 are cross-sectional views taken along line A-A 'of still another embodiment of the present invention. As shown, the graphite sheet 400, the base graphite sheet 700, the lower graphite sheet 800 can be seen that the thickness is different for each position in the casing (100). The thicker side represents the upper side of the casing 100, and the thinner side represents the lower side of the casing 100. The reason for the difference in thickness 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 is varied as shown in FIGS. 12 to 21. By varying the thickness as described above, damage caused by stress can be prevented by minimizing the difference in temperature distribution in the lighting unit.

For reference, in FIGS. 14 to 17, the bottom sash shape of the casing 100 may be inclined or stepped. This is because when the thickness of the base graphite sheet 700 is changed in a state in which the batam sash shape of the casing 100 is straightened, luminance deviation occurs due to the height difference of the LEDs 300. Therefore, the bottom chassis of the casing 100 is inclined or stepped to prevent occurrence of luminance deviation. However, the present invention is not limited to this form, and a shape capable of making the height of the LED 300 constant may be sufficient.

In another embodiment, the density may be varied. In other words, instead of making the thickness thicker, the density is increased, and instead of making the thickness thinner, the density is lowered. This different density can be achieved by varying the degree of compression of the graphite sheet. To increase the density, increase the degree of compression to make the graphite fiber itself more compact, and to decrease the density, decrease the degree of compression. By varying the density, the difference in temperature distribution in the lighting unit can be minimized to prevent damage caused by stress.

According to an additional aspect of the present invention, the base graphite sheet 700 and the lower graphite sheet 800 may include a metal mesh 450 therein. As shown in FIG. 22, the metal mesh 450 may be a sheet-like sheet formed by weaving a metal wire, may be 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 450, it is preferable to have a high thermal conductivity such as copper, stainless steel, platinum, aluminum, titanium, nickel and the like. Since the metal mesh 450 is excellent in flexibility, even if it is included in the base graphite sheet 700 or the lower graphite sheet 800, the flexibility does not decrease. The manufacturing method of including the metal network 150 inside the graphite sheet may be made by rolling a metal network between the graphite sheets as shown in FIG. 23.

The reason for placing the metal mesh 450 inside the sheet made of graphite is to change the anisotropic property of the sheet to further increase the heat dissipation effect. Since the graphite sheet having anisotropic characteristics diffuses heat generated from the LED 300 in the plane direction but not in the thickness direction, the graphite sheet has a metal mesh 450 in the graphite sheet so that its properties are isotropic. To change. Accordingly, the base graphite sheet 700 and the lower graphite sheet 800 can diffuse heat well in the thickness direction as well as the surface direction, thereby providing an advantage of further improving the heat dissipation effect. Since the graphite sheet itself is a known technical configuration, detailed description thereof will be omitted.

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As described above, according to the present invention, by adopting a graphite sheet having high thermal conductivity, low cost, and flexibility, high adhesion, heat generated by LEDs can be more efficiently diffused and radiated. Since it has a structure attached to the LED (heating element), the heat dissipation efficiency can be further increased.

In addition, in the present invention, by employing a graphite sheet in the upper and lower portions of the casing bottom chassis, heat can be more effectively diffused and radiated.

In addition, the present invention can increase the brightness, that is, display brightness by re-reflecting the light reflected from the configuration that is irradiated from the LED (LED) to transmit the 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, 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. Accordingly, the true scope of the present invention should be determined only by the appended claims.

Claims (16)

A metal PCB supplying an electrical driving signal to a plurality of LEDs arranged side by side; A graphite sheet stacked on the metal PCB, except for laminating positions of the LEDs; LED substrate for illumination comprising a. The method of claim 1, wherein the substrate is: A reflective layer coated on the graphite sheet; LED substrate for illumination comprising a further. Metal PCB; A plurality of LEDs (LEDs) arranged side by side on the metal PCB to receive electric driving signals from the metal PCB to emit light; A graphite sheet stacked on the metal PCB, except for laminating positions of the LEDs; Lighting unit comprising a. The method of claim 3 wherein the unit is: A reflective layer coated on the graphite sheet; Lighting unit further comprises. Casing; At least one metal PCB overlying the casing; A plurality of LEDs (LEDs) arranged side by side on the metal PCB to receive an electric driving signal and emit light; A graphite sheet in contact with the metal PCB, except for the arrangement position of the plurality of LEDs; Lighting unit comprising a. The method of claim 5, wherein the unit is: A gap pad in contact between the casing and the metal PCB; Lighting unit further comprises. 6. The lighting unit according to claim 5, wherein the graphite sheet in contact with the metal PCB on the upper side of the casing is thicker or denser than the graphite sheet in contact with the metal PCB on the lower side. The method of claim 5, wherein the unit is: Lighting unit, characterized in that the plurality of graphite sheets in contact with the plurality of metal PCB is formed integrally with the whole. The method of claim 8, wherein the graphite sheet is: Illumination unit, characterized in that the portion in contact with the metal PCB placed on the upper side of the casing is thicker or denser than the portion in contact with the metal PCB placed on the lower side. 10. The method of claim 5 or 9, wherein the unit is: A reflective layer coated on the graphite sheet; Lighting unit further comprises. The method of claim 5 or 9, wherein the lighting unit is: A graphite sheet for the base in contact with the casing and the plurality of metal PCBs; Lighting unit further comprises. The method of claim 11, wherein the base graphite sheet is: Lighting unit, characterized in that the portion in contact with the upper surface of the casing is thicker or denser than the portion in contact with the lower surface. The method of claim 11, wherein the base graphite sheet is: Lighting unit, characterized in that it comprises a metal network inside. The method of claim 5 or 9, wherein the lighting unit is: A lower graphite sheet in contact with the lower casing; Lighting unit further comprises. The method of claim 14, wherein the lower graphite sheet is: Lighting unit, characterized in that the portion in contact with the upper surface of the casing is thicker or denser than the portion in contact with the lower surface. The method of claim 14, wherein the lower graphite sheet is: Lighting unit, characterized in that it comprises a metal network inside.

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