KR20010046076A - Backlight assembly of LCD - Google Patents

Abstract

PURPOSE: A back light assembly for a liquid crystal display device is to transmit heat generated in a lamp to a lamp reflective plate effectively, thereby improving heat transfer efficiency and prolonging a life span of a lamp unit. CONSTITUTION: The back light assembly for a liquid crystal display (LCD) device comprises a mold frame, a reflective plate, a light guide plate, a plurality of optical sheets, a lamp unit(140) and a bottom chassis. In the lamp unit, a lamp(143) for emitting light has a hot electrode and a cold electrode formed on one terminal and the other terminal thereof, respectively. A lamp holder for holding the lamp is inserted between both terminals of the lamp. A lamp reflective plate(147) reflects light emitted from the lamp toward the light guide plate. A plurality of heat sink plates(150) mounted between the lamp holders are in contact with the lamp and the lamp reflective plate.

Description

Backlight assembly of LCD device

The present invention relates to a backlight assembly of a liquid crystal display device, and more particularly, to a liquid crystal display in which a plurality of heat sinks providing a heat transfer path between a lamp and a lamp reflector is installed on the lamp to effectively dissipate heat generated from the lamp to the lamp reflector. It relates to a backlight assembly of a device.

Cathode ray tube (CRT), which is one of the commonly used display devices, is mainly used for monitors such as televisions, measuring devices, information terminal devices, etc., but due to its own weight and size, It could not actively respond to the demand for miniaturization and weight reduction.

In order to replace the cathode ray tube, it has advantages such as small size, light weight, low power consumption, and the like, and a liquid crystal display device that displays information by using the electrical and optical properties of the liquid crystal injected into the LCD panel has been actively developed. The function has been improved so that it can fully function as a flat panel display device.

Unlike the cathode ray tube, such a liquid crystal display device is not a light emitting material that can generate light, but a liquid crystal material injected between the TFT substrate and the color filter substrate. A separate light source for irradiating light to the LCD panel, that is, a backlight assembly is necessary, and the performance of the backlight assembly greatly affects the display quality of the liquid crystal display device.

The backlight assembly may include a reflective sheet configured to sequentially stack a mold frame having a storage space, a bottom chassis fastened to the bottom surface of the mold frame, and a storage space formed between the bottom chassis and the mold frame, and transmit light to the LCD panel. A light guide plate, an optical sheet and a lamp unit installed on the side of the light guide plate to emit light, and a top chassis covering from the predetermined portion of the edge of the LCD panel installed on the upper part of the mold frame to the side of the frame.

At least one lamp unit is installed on the side of the light guide plate, and at least one lamp that emits light, and diffuses the light emitted from the lamp to the light guide plate to improve light efficiency and to power the lamp reflector and lamp that surrounds the outer surface of the lamp. It includes an inverter for supplying.

In such a structure, since the lower surface of the lamp reflector is in contact with the bottom chassis, the heat generated in the lamp is discharged to the outside through the bottom chassis, thereby lowering the ambient temperature of the lamp unit. Here, the heat transfer path through which heat generated from the lamp is transferred to the bottom chassis is as follows. First, most of the heat generated in the lamp is transmitted to the lamp reflector by radiation of air, and part of it is directly transmitted to the lamp reflector through a rubber lamp holder, and heat transmitted to the lamp reflector is discharged to the outside through the bottom chassis. .

However, as described above, most of the heat generated in the lamp is transferred to the lamp reflector by radiation, and part of the heat is conducted to the lamp reflector through the rubber lamp holder to radiate heat, so the heat radiation efficiency is lowered. This is because heat transfer due to radiation is significantly lower in efficiency than heat transfer due to conduction, and in the case of a lamp holder, heat dissipation due to conduction is hardly achieved due to a low thermal conductivity coefficient due to the rubber system.

Therefore, when the liquid crystal display is gradually enlarged and the lamp is lengthened, and two or more lamps are installed in one lamp unit to obtain sufficient brightness, the lamps may not be effectively transferred to the lamp reflector. Since the generated heat is not sufficiently released to the outside through the bottom chassis, the ambient temperature of the lamp unit is raised, which causes various problems.

In other words, the temperature of the lamp is increased to lower the brightness of the lamp.

In addition, the lamp and the lamp reflector deteriorate to shorten the life, and the mold frame and the lamp holder adjacent to the lamp unit are deformed by heat.

The reason why the life is reduced when the lamp reflector is deteriorated is that the light reflecting film (silver) melts and agglomerates by heat or penetrates into the resin in the lamp reflector including the resin and the light reflecting film, thereby decreasing the reflecting efficiency of the lamp reflecting plate.

Accordingly, it is an object of the present invention to efficiently transfer heat generated in a lamp to a lamp reflector to extend the life of the lamp unit and to prevent the mold frame from being deformed by heat.

Another object of the present invention is to maintain the temperature of the lamp at an appropriate level at which the highest brightness is achieved.

Other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is a graph for explaining the temperature distribution of the lamp,

2 is an exploded perspective view showing the structure of a liquid crystal display device according to the present invention;

3 is a cross-sectional view taken along line III-III of FIG. 2;

Figure 4 is an exploded perspective view showing the structure of the lamp unit according to the present invention.

5 is a perspective view showing the structure of a heat sink according to the present invention;

6 is a cross-sectional view taken along line VI-VI of FIG. 4.

7 is an enlarged view illustrating main parts of an enlarged portion A of FIG. 6;

Figure 8 is a graph comparing the heat transfer coefficient of the heat dissipation sheet and the other materials according to the present invention.

Lamp unit of the present invention for achieving the above object is a hot electrode is formed at one end and the cold electrode is formed at the other end of the at least one lamp to emit light, the lamp holder is inserted into both ends of the lamp, the light guide plate A lamp reflector and a lamp insertion hole are formed to surround the lamp from the end of the lamp and reflect the light emitted from the lamp to the light guide plate, and a plurality of lamp reflector plates are installed between the lamp holders and are in contact with the lamp and the lamp reflector to transfer heat generated from the lamp to the lamp reflector. By including the heat sink to increase the heat dissipation efficiency.

For example, at least one heat sink is densely installed around a hot electrode and a cold electrode having the highest temperature when the lamp is turned on. Among these heat sinks, light is hardly emitted and the heat sink installed at the closest part to the lamp holder is Thicker than the heat sinks.

Preferably, the front surface of the heat sink facing the lamp holder and the back surface opposite to the lamp holder are formed with a diffuse reflection portion to improve the brightness of the lamp, and is in contact with the lamp to prevent the leakage current is generated by the metal heat sink The heat radiation pad of insulating material is formed in the outer peripheral surface of the lamp insertion hole to a predetermined thickness.

In one example, the heat dissipation pad is heat dissipation silicon.

Hereinafter, the backlight assembly of the liquid crystal display according to the present invention will be described with reference to FIGS. 1 to 8.

As shown in FIG. 1, the liquid crystal display 100 according to the present invention includes a mold frame 110 having storage spaces 111 and 113 penetrated from an upper surface to a lower surface, and a storage space 113 of the mold frame 110. ) Is a light reflector plate 120 that is reflected in the light reflecting light, the light guide plate 130 is laminated on the upper surface of the reflecting plate 120, the lamp unit is fitted to the side of the light guide plate 130 in a sliding manner to emit light 140, the optical sheets 135 stacked on the upper surface of the light guide plate 130 and diffusing and condensing the light transmitted from the light guide plate 130, are fastened to the lower surface of the mold frame 110 to reflect the plate 120. The bottom chassis 160 supporting the light guide plate 130, the lamp unit 140, and the optical sheets 135, the LCD panel 170 and the mold frame installed on the optical sheets 135 to display information. It is fastened on the upper surface of the 110 is composed of a top chassis 180 for supporting the LCD panel 170.

Among them, the mold frame 110 has a rectangular shape corresponding to the LCD panel 170, and storage spaces 111 and 113 having a predetermined depth are formed on the upper and lower surfaces thereof, and the storage space formed on the lower surface side of the mold frame 110. The reflective plate 120, the light guide plate 130, and the optical sheets 135 are sequentially stacked on the 111, and the lamp units 140 are installed on the side surfaces of the light guide plate 135.

The LCD panel 150 is accommodated in the storage space 113 formed on the upper surface of the mold frame 110, and the LCD panel 150 is a part of the LCD panel 150 that is displayed on the base surface of the storage space 113. An open area larger than the screen display area is formed so that light emitted from the optical sheets 135 is incident on the LCD panel 150.

In addition, a slide groove 115 is formed on one side of the mold frame 110 in a longitudinal direction to separate and assemble the lamp unit 140 in a slide manner from the side of the liquid crystal display 100.

As shown in FIG. 3, the lamp unit 140 includes at least one lamp 143 and a lamp 143 that emit light by forming a hot electrode 141 at one end and a cold electrode 142 at the other end thereof. The lamp holder 145 which is inserted at both ends of the lamp 143 to protect the lamp 143, and covers the lamp 143 and faces the light guide plate 130, and is fitted at one end in the width direction of the light guide plate 130. Lamp reflection plate 150 for diffusely reflecting the light emitted from the light guide plate 130 to improve the efficiency of the light, a plurality of heat sinks 150 are installed along the longitudinal direction of the lamp 143 to properly maintain the temperature of the lamp 143 And an inverter (not shown) electrically connected to the lamps 143 by a wire 147 to supply power to the lamps 143.

When the lamp unit 140 configured as described above is driven and the lamps 143 are turned on, heat is emitted from the lamps 143 to 60 ° C. to 180 ° C. as shown in FIG. 1. The heat dissipation plate 150 connects the lamp 143 and the lamp reflector 147 to rapidly conduct and release heat generated from the lamp 143 to the lamp reflector 147 to lower the temperature of the lamp 143.

The heat sink 150 is formed of a metal material, for example, aluminum, which is easy to process and has excellent thermal conductivity. In order to effectively discharge heat generated from the lamp 143 to the lamp reflector 147, the lamp temperature of FIG. As shown in the distribution diagram, when the lamp 143 is turned on, a plurality of heat sinks 150 are densely installed in the hot electrode 141 and the cold electrode 142 where the temperature rises by 150 ° C. or more, and the temperature is relatively about 60 ° C. Install one heat sink 150 at the center of the lower lamp (see Figure 4).

Here, the light is hardly emitted, but the heat dissipation plate 150a having a thick thickness is formed at a predetermined portion of the hot electrode 141 and the cold electrode 142 having a high temperature of the lamp 143, that is, the portion closest to the lamp holder 145. And a heat sink 150b having a thin thickness in order to prevent the brightness of the light from being lowered.

If the two heat sinks 150a installed adjacent to the lamp holder 145 have a sufficient thickness and have a large heat dissipation effect, the temperature of the hot electrode 141 and the cold electrode 142 may be set at the center of the lamp 143. When the temperature is lowered close to the temperature, only two heat sinks 150a may be installed at a portion adjacent to the lamp holder 145.

As described above, when at least two heat sinks 150 are installed along the longitudinal direction of the lamp 143, the efficiency of light may be reduced due to the heat sinks 150. As described above, a diffuse reflection part 155 is formed on the front surface of the heat sink 150 facing the lamp holder 145 and the rear surface opposite to the lamp holder 145 to increase the amount of light incident on the light guide plate 130.

Preferably, the diffuse reflection part 155 is formed by attaching a diffusion sheet, or is formed by coating silver, or is formed by depositing aluminum.

In addition, when the metal heat sinks 150 connect the lamp 143 and the lamp reflector 147, the current flowing through the lamp 143 leaks to the lamp reflector 147 through the heat sink 150. The power consumption of the device 100 is increased and the brightness of the lamp 143 is lowered. In order to prevent this, the present invention provides a heat dissipation pad 153 formed of an insulating material and having good thermal conductivity on the outer circumferential surface of the lamp insertion hole 151 (see FIG. 5) in which the lamp 143 is fitted. Attach.

Preferably, the heat radiation pad 153 is a material having a heat transfer coefficient higher than the heat transfer coefficient (0.026 W / mK) of air for transferring heat to the lamp reflector 147 by radiation, that is, mica and silicon as shown in FIG. 8. It is formed of rubber, polystyrene, polyester, polystyrene, heat dissipation silicone.

However, the most preferable heat dissipation pad 153 is heat dissipation silicon used as a heat sink in various semiconductor chip packages, and as shown in FIG. 8, the heat transfer coefficient is 2.6 W / m-K, which is four times higher than that of general silicon.

Here, the heat transfer amount is proportional to the contact area and the thermal conductivity coefficient and inversely proportional to the thickness of the heat radiation pad 153, so that the heat radiation pad 153 is formed to a minimum thickness for insulation between the lamp 143 and the heat sink 150.

As described above, even when the heat-dissipating pad 153, which is an insulating material, for example, heat-dissipating silicon is applied to the outer circumferential surface of the lamp insertion hole 151 in contact with the lamp 143, the heat-dissipating silicon has a higher heat transfer coefficient than that of air. The heat dissipation efficiency is greatly increased.

Preferably, the thick heat dissipating plate 150a attaches heat-dissipating silicon in a tape form to the outer circumferential surface of the lamp insertion hole 151 to form a heat dissipation pad 153, and the thin heat dissipating plate 150b dissipates liquid in heat dissipation. Silicon is applied around the lamp insertion hole 151 and then cured to form a heat radiation pad 153.

Meanwhile, the mold frame of the bottom chassis which lowers the ambient temperature of the lamp unit 140 by contacting the lower surface of the lamp reflector 147 and dissipating heat transferred to the lamp reflector 147 by the heat sinks 150 to the outside. In the portion corresponding to the slide groove 115 of the 110, the lamp unit 140 is moved outside the liquid crystal display device 100 even when the mold frame 110, the bottom chassis 160, and the top chassis 180 are coupled to each other. Slide groove 165 is formed to be pulled out or assembled into.

Finally, the top chassis 180 is formed with an open area 183 for exposing the screen of the LCD panel 170 to the outside in a portion corresponding to the screen display area of the LCD panel 170, the top chassis 180 The slide groove 185 is also formed at a portion of the side surface corresponding to the slide grooves 115 and 165 formed in the mold frame 110 and the bottom chassis 160.

The assembly process and operation of the liquid crystal display according to the present invention configured as described above will be described with reference to FIGS. 1 and 3.

First, the optical sheets 135, the light guide plate 130, and the reflecting plate 120 are sequentially stacked in a state in which the mold frame 110 is inverted so that the storage space 111 formed on the lower surface side of the mold frame 110 is exposed. The bottom chassis 160 is fastened to the bottom surface of the mold frame 110 so that the reflector 120, the light guide plate 130, and the optical sheets 135 accommodated in the accommodation space 111 may be supported.

Subsequently, the LCD panel 150 is installed in the storage space 113 while the mold frame 110 is turned upside down so that the storage space 113 formed on the upper surface side of the mold frame 110 is exposed. The top chassis 170 is fastened at the top of the LCD panel 150 to support the LCD panel 150 accommodated therein.

Then, the slide grooves 115, 165, and 185 formed on one side of the short side of the mold frame 110, the bottom chassis 160, and the top chassis 180 are exactly matched, and the lamp unit 140 flows into the liquid crystal display 100. Form a passageway so that it can be.

Separately, a plurality of heat sinks 150 are provided in each lamp 143 by connecting the lamp 143 and the lamp reflector 147 to provide a heat transfer path. 4 and 6, only one heat sink 150b is installed at the center of the lamp 143 having the brightest and lowest temperature among the lights emitted from the lamp 143, and the light emitted from the lamp 143. A plurality of heat sinks 150a and 150b are densely installed around the hot electrode 141 and the cold electrode 142 of the lamp 143 which is relatively dark and the temperature of the lamp 143 is higher than the center portion. In addition, although the light is hardly emitted, the temperature of the lamp 143 is 150 ° C. or higher, and the hot electrode 141 and the cold electrode 142 of the lamp 143 having a higher thickness than the other heat sinks 150b are provided. 150a) are installed respectively.

Subsequently, rubber lamp holders 145 are inserted at both ends of the lamp 143 so as to face the heat sink 150, and the outer circumferential surfaces of the lamp 143, the lamp holder 145, and the heat sinks 150 are disposed on the lamp reflector plate ( 147 is assembled with the lamp unit 140. At this time, the upper surface and the lower surface of the heat dissipation plate 150 and the rounded one side surface is in contact with the lamp reflector plate 147 and the lamp insertion hole 151 is in contact with the lamps 143. A heat transfer path by conduction is formed between the reflecting plates 147.

Meanwhile, when a passage is formed due to the slide grooves 115, 165, and 185, the lamp unit 140 assembled by the above-described method is introduced into the liquid crystal display 100, and the cold electrode 142 of the lamp unit 140 is introduced. One end of the lamp unit 140 is positioned adjacent to the slide grooves 115, 165 and 185, and then the lamp unit 140 is pushed toward the liquid crystal display device 100 so that one end of the lamp unit 140 moves away from the slide grooves 115, 165 and 185. The lamp unit 140 is inserted into the inside of the 100.

When the liquid crystal display device 100 is assembled by the above-described method, high temperature heat is generated from the lamp 143. As shown in FIG. 6, the heat generated from the lamp 143 is transferred to the lamp 143. Heat is transferred to the lamp reflector 147 in a short time through the heat sinks 150 directly connecting the lamp reflector 147 to the lamp reflector 147, and the heat transferred to the lamp reflector 147 is again transferred to the bottom chassis 160. The temperature of the lamp 143 is lowered because it is delivered to the outside and released to the outside.

That is, heat dissipation plates 150 are densely arranged at both ends of the lamp 143 that emits heat of about 150 ° C. and 180 ° C., and a thick heat dissipation plate 150a is installed. It is transmitted to the reflector plate 147 to properly maintain the temperature of the lamp unit 140.

Therefore, the heat transfer efficiency of the heat dissipation plate 150 of the metal material is superior to the heat transfer by the conventional radiation, so that the liquid crystal display device 100 is enlarged so that the length of the lamp 143 is increased and the number of lamps 143 is increased. Even if the temperature of the lamp unit 140 can be properly maintained.

In addition, since the heat sink 150 is inserted into the lamp 143 to support the lamp 143, sagging of the lamp 143 may be prevented.

As described above, the present invention improves the heat transfer efficiency of transferring heat generated from the lamp to the lamp reflector by installing a heat sink between the lamp and the lamp reflector, thereby maintaining the temperature of the lamp unit appropriately.

Then, the deterioration of the gas encapsulated in the lamp can be prevented, so that the life of the lamp is increased, the brightness of the lamp is increased, and the silver coated on the lamp reflector can be prevented from melting and agglomeration by the heat or infiltration of silver into the resin. Therefore, the life of the lamp reflector is increased.

In addition, since the ambient temperature of the lamp unit is lowered, the mold frame can be prevented from being deformed, thereby improving the reliability of the product.

Claims (9)

A mold frame having a receiving space penetrating from an upper surface to a lower surface; A reflection plate accommodated in the storage space to reflect light; A light guide plate laminated on an upper surface of the reflector to guide light toward an LCD panel displaying information; Optical sheets stacked on an upper surface of the light guide plate to improve brightness of light and transmit the light to the LCD panel; A lamp unit installed on a side of the light guide plate by a sliding method to emit light; And A bottom chassis fastened to a lower surface of the mold frame to support the reflective plate, the light guide plate, the optical sheets, and the lamp unit; The lamp unit At least one lamp having a hot electrode formed at one end and a cold electrode formed at the other end to emit light; A lamp holder inserted at both ends of the lamp to support the lamp; A lamp reflection plate surrounding the lamp from an end of the light guide plate and reflecting the light emitted from the lamp to the light guide plate; And A plurality of lamp insertion holes are formed between the lamp holders and contact the lamp and the lamp reflector to transfer heat generated from the lamp to the lamp reflector to increase heat dissipation efficiency. The backlight assembly of the liquid crystal display device. The backlight assembly of claim 1, wherein at least two heat sinks are densely installed around the hot electrode and the cold electrode having the highest temperature when the lamp is turned on. 3. The liquid crystal display of claim 2, wherein light is hardly emitted from a plurality of heat sinks disposed around the hot electrode and the cold electrode, and a heat sink installed at a portion closest to the lamp holder is thicker than the thickness of the remaining heat sinks. Backlight assembly of the device. 3. The backlight assembly of claim 2, wherein a heat sink is further installed at the center of the lamp at the lowest temperature and the brightest light when the lamp is turned on. The backlight assembly of claim 1, wherein a diffuse reflection part is formed on a front surface of the heat sink facing the lamp holders and a back surface opposite to the lamp holders to improve brightness of the lamp. The backlight assembly of claim 5, wherein the diffuse reflection part is formed by one of a method selected from a diffusion sheet, silver coating, and aluminum deposition. The backlight assembly of claim 1, wherein the heat sinks are made of metal having good thermal conductivity. 8. The backlight of the liquid crystal display device according to claim 7, wherein a heat insulating pad made of an insulating material is formed on an outer circumferential surface of the lamp insertion hole in contact with the lamp to prevent a leakage current from being generated by the heat sink. assembly. The backlight assembly of claim 8, wherein the heat dissipation pad is heat dissipation silicon.