KR100767956B1 - Backlight unit using thermal conductive resin for liquid crystal display - Google Patents

Abstract

 The present invention relates to a backlight unit used in a liquid crystal display device, and more particularly, a reflector positioned below the lamp of the backlight unit to reflect light emitted from the lamp downward, a support for supporting the lamp, and heat dissipation. The lower plate that can play a role is made of the same thermally conductive material to solve the heat problem of the backlight unit effectively and relates to a backlight unit of the liquid crystal display device having an effect that can simplify the manufacturing process.

Backlight Unit, Heat, Thermally Conductive, Thermoplastic, Liquid Crystal Display

Description

BACKLIGHT UNIT USING THERMAL CONDUCTIVE RESIN FOR LIQUID CRYSTAL DISPLAY}

The present invention relates to a backlight unit used in a liquid crystal display device, and more particularly, a reflector disposed below the lamp to reflect light emitted from the lamp downward, a support for supporting the lamp, and a heat dissipation role. The present invention relates to a backlight unit of a liquid crystal display device which can be manufactured in one piece by applying a resin of the same thermally conductive material to a lower plate, thereby effectively solving the heat generation problem of the backlight unit.

Liquid crystal display (hereinafter, referred to as 'LCD') devices generally do not have self-illumination functions, unlike cathode ray tubes, and thus require a light emitting device capable of maintaining the entire screen with uniform brightness.

In general, LCDs are divided into a transmissive type using a backlight unit including a separate light source and a reflective type using external light as a light source according to the method of the light source. Many studies have been conducted because of the low consumption, but when the brightness of the external light source is not sufficient, its visibility is low, and it is not sufficiently utilized. In the case of transmissive LCDs, which are currently being actively used, the supply of a light source with uniform brightness through the backlight unit is a very important factor.

The backlight unit has a light source placed on the bottom of the liquid crystal panel to illuminate the entire surface of the substrate, and an edge method that distributes light evenly through the light guide plate and the reflector by placing the light sources on both sides of the unit. system).

The edge method has uniform brightness and low power consumption, so it is mainly used in small LCD monitors or notebook computers, but a light guide plate is necessary to evenly distribute light on the side.

In the case of the direct method, the light source directly illuminates the substrate, so the light utilization rate is high, and there is no size limitation, so it can be applied to large LCD TVs and monitors, but since the light source is located very close to the panel and the number of lamps increases, Increasing problems may occur, and excessive generation of heat may cause screen staining, which may be a major cause of shortening the life of the LCD panel. In particular, in recent years, as the size and thickness of LCDs have increased, the heat generation of the backlight unit has emerged as a problem that must be solved.

The structure of a general direct backlight unit is as follows.

In the direct backlight unit, a support for supporting a panel is positioned around a lamp which is a light source, and a diffusion sheet, a prism sheet, and a dual brightness enhancement film (DBEF) sheet are sequentially disposed on the lamp. The lower part of the lamp is disposed with a reflecting plate to prevent the leakage of light, an outer support and a lower plate that serves as heat dissipation.

 Among the components of the backlight unit, the white polyester film is improved in Japanese Patent Application Laid-Open No. Hei 4-239540, Japanese Patent Application Laid-Open Nos. 2002-98811, 2002-138150 and 2001-305321. Disclosed is a technique.

U.S. Patent No. 5,837,757, Japanese Patent Application Laid-open No. Hei 7-242781 and Japanese Patent Application Laid-open No. Hei 9-176471 disclose a technique for reflectance and impact resistance of a white polycarbonate resin.

Japanese Laid-Open Patent Publication No. 1999-181267 discloses a technique for manufacturing a reflective sheet using a flame retardant white polycarbonate resin.

In the conventional reflector manufacturing technology, a method of improving the reflectance, heat resistance, impact resistance, and the like of the reflector is mentioned, but no attempt has been made to solve the heat generation problem of the backlight unit by applying a heat conductive material to the reflector.

Korean Patent Laid-Open Publication No. 2004-0017718 discloses a technique for solving a heat generation problem of a backlight unit by applying a metallic material such as aluminum having high thermal conductivity to a lower plate of a backlight unit, but there is a reflector between the heating element and the lower plate. Located there is a problem that hinders the heat generation problem, the price of the product rises.

In order to solve the problems of the prior art as described above, in the manufacturing of the backlight unit of the liquid crystal display device, the manufacturing process by applying the same thermoplastic thermal conductive resin having excellent thermal conductivity to the reflecting plate, the support and the lower plate plate by applying the same It is an object of the present invention to provide a backlight unit of a liquid crystal display device which simplifies and improves heat dissipation performance.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention is a backlight unit of the liquid crystal display device, the reflector is located under the lamp of the backlight unit reflecting the light emitted from the lower part, the support for supporting the lamp And it provides a backlight unit of the liquid crystal display device, characterized in that the lower plate which can serve as a heat dissipation is made of the same material.

In order to effectively radiate the heat generated from the heating element such as the light source lamp of the backlight unit to the outside, the thermal conductivity of the material used as the heat transfer medium must be high and the contact area with the outside atmosphere is wide. The material of the present invention has a high heat dissipation performance because the general plastic thermal conductivity is 0.2 W / mK at room temperature, while having a thermal conductivity of 0.35 W / mK or more.

The reflector plate, support plate and bottom plate of the backlight unit are separate products, and each material is generally different. In the case of the reflecting plate and the support, it is common to manufacture using a polyester or polycarbonate resin composition, and in the case of the lower plate, it is common to use a metal material having good thermal conductivity because the role of heat dissipation is important. However, it is difficult to obtain effective heat dissipation performance because the characteristics of each material are different even when the reflector plate, the support plate, and the lower plate are manufactured and manufactured using the conventional manufacturing method. Accordingly, when the reflector plate, the support plate and the lower plate plate using the thermoplastic thermally conductive resin of the present invention are integrated, the manufacturing process can be simplified and the cost reduction effect can be achieved, and since the whole is made of the same excellent thermal conductivity material, it is very effective. Heat dissipation performance can be obtained.

Hereinafter, the present invention will be described in detail.

The same material is a thermoplastic heat conductive resin composition disclosed in the technology related to the production of a thermoplastic resin composition of the Republic of Korea Patent No. 450229, which is filed by the applicant, the reflector for a backlight unit because of excellent workability and mechanical properties, The support and the bottom plate can be integrally molded to simplify the manufacturing process of the backlight unit and improve heat dissipation performance.

The thermoplastic thermally conductive resin may be a thermally conductive thermoplastic resin composition comprising a) 10 to 95% by weight of a thermoplastic resin, and b) 90 to 5% by weight of a ceramic solid having a thermal conductivity of 300 W / mK or more at room temperature.

The thermoplastic resin is polybutylene terephthalate, polyethylene terephthalate, aromatic polyamide, polyamide, polycarbonate, polystyrene, polyphenylene sulfide, thermotropic liquid crystal polymer, polysulfone, polyether sulfone, polyetherimide, polyether Ether ketone, polyarylate, polymethylmethylacrylate, polyvinyl alcohol, polypropylene, polyethylene, polyacrylonitrile butadiene styrene copolymer and polytetramethylene oxide-1,4-butanediol copolymer, including styrene It can select and use at least 1 sort (s) from the group which consists of a copolymer, a fluororesin, a polyvinyl chloride, and a polyacrylonitrile. The thermoplastic resins do not limit the present invention, and all kinds of thermoplastic resins are applicable.

The thermoplastic resin is preferably included in 10 to 95% by weight.

The ceramic solid is used to obtain a thermoplastic resin composition having a high thermal conductivity of 0.35 W / mK or higher at room temperature, and has boron nitride, silicon carbide, diamond, beryllium oxide, and boron force having a thermal conductivity of at least 300 W / mK at normal temperature. At least one selected from the group consisting of fides, aluminum nitride, beryllium sulfide, boron azenide, silicon, gallium nitride, aluminum phosphide, and gallium phosphide can be used.

The ceramic solid is preferably included in 5 to 90% by weight.

The thermoplastic thermally conductive resin may further comprise at least one filler selected from the group consisting of flakes, glass fibers, and halogen or non-halogen-based flame retardants.

The halogen or non-halogen flame retardant is bromine carbonate oligomer, Sb ₂ O ₃ , phosphorus and phosphate flame retardant, melamine cyanurate, melamine, triphenyl isocyanurate, melamine phosphate, melamine pyrophosphate, ammonium polyphosphate , Alkyl amine phosphate, melamine resin and zinc borate can be selected from the group consisting of one or more.

The filler is preferably included in 5 to 15% by weight.

The thermoplastic thermal conductive resin may further include a white dielectric material to improve light reflectance.

The white dielectric material may be used by selecting one or more from the group consisting of BaSO ₄ , TiO ₂ , SiO ₂ , B ₂ O _3, and Al ₂ O ₃ .

The white dielectric material may be included in an amount of 5 to 40 wt%, and the total amount of the white dielectric material and the ceramic solid may be 90 wt% or less.

The thermoplastic thermal conductive resin may be prepared by mixing and extruding in a twin screw extruder. At this time, the barrel temperature of the twin screw extruder is preferably maintained at 250 to 340 ℃.

It is preferable that said thermoplastic thermal conductive resin is 0.35 W / mK or more in thermal conductivity. When the thermal conductivity is 0.35 W / mK or more, it is effective for heat dissipation of the backlight unit, and has excellent processability, light reflectivity, and mechanical rigidity, thereby enabling the manufacture of an integrated structure of a reflector, a support, and a lower plate.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Specimens of the following examples and comparative examples were prepared by injection molding the specimen standard according to each measurement method. For example, the thermal conductivity measurement specimen was manufactured by injection molding a molded specimen having a diameter of 10 mm and a thickness of 3 mm. The physical properties of the resin compositions and the specimens of Examples and Comparative Examples were measured based on the following methods.

Heat Deflection Temperature: ASTM D648

Flexural Modulus: ASTM D790

Tensile Elongation: ASTM D638

Thermal conductivity: Data within 10% error were used in three methods: plate method (LG Chem Tech Center), heat ray method (Research Institute of Standards and Science) and Hakke Thermoflixer.

Reflectance: Spectrophotometer (Shmadzu UV-3101PC) was used to measure total reflectance at a wavelength of 550 nm.

Example 1

Specimens were prepared from a resin composition consisting of 60% by weight polyethylene terephthalate resin (manufactured by LG Chem) and 40% by weight of boron nitride. The thermal conductivity of the polyethylene terephthalate-based resin composition and the specimen was 0.38 W / mK, the total reflectance at 550 nm wavelength of the specimen was 93%, the heat deformation temperature is 90 ℃, the flexural modulus is 50000 kg / cm ² , Tensile elongation was 5%.

Example 2

Specimens were prepared from a resin composition consisting of 60 wt% polybutylene terephthalate resin (manufactured by LG Chem), 25 wt% boron nitride, and 15 wt% TiO ₂ . The thermal conductivity of the polybutylene terephthalate resin composition and the specimen was 0.4 W / mK, the total reflectance at the 550 nm wavelength of the specimen was 92%, the heat deformation temperature was 130 ℃, the flexural modulus was 45000 kg / cm ² , tensile elongation was 4%.

Example 3

Specimens were prepared from a resin composition consisting of 60% by weight of polycarbonate resin (manufactured by LG Chem), 20% by weight of boron nitride, and 20% by weight of TiO ₂ . The thermal conductivity of the polycarbonate-based resin composition and the specimen was 0.42 W / mK, the total reflectance at the 550 nm wavelength of the specimen was 95%, the heat deformation temperature is 130 ℃, flexural modulus is 50000 kg / cm ² , tensile Elongation was 4%.

Comparative Example 1

Specimens were prepared from a resin composition consisting of 90% by weight of polycarbonate resin (manufactured by LG-DOW) and 10% by weight of TiO ₂ . The thermal conductivity of the polycarbonate-based resin composition and the specimen was 0.23 W / mK, the total reflectance at 550 nm wavelength of the specimen was 85%, the heat deformation temperature is 120 ℃, flexural modulus is 26000 kg / cm ² , tensile Elongation was 130%.

As described above, the backlight unit of the liquid crystal display device manufactured by using the thermoplastic thermal conductive resin according to the present invention may be made of the same material as the reflector, the support and the lower plate, thereby simplifying the manufacturing process, and having excellent thermal conductivity. Therefore, it is very effective in heat dissipation of heat generated from the lamp of the backlight unit, and has an effect of improving durability of the liquid crystal display device because of excellent heat resistance and mechanical strength and excellent reflectance.

Although described in detail above with reference to the specific embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such modifications and modifications belong to the appended claims. It is also natural.

Claims (8)

In the backlight unit of the liquid crystal display device, Liquid crystal display, characterized in that the reflector is positioned under the lamp of the backlight unit to reflect the light emitted from the lamp to the lower, the support for supporting the lamp and the lower plate that can act as a heat radiation is made of the same material Backlight unit of the device. The method of claim 1, And the same material is a thermoplastic thermal conductive resin having a thermal conductivity of 0.35 W / mK or more. The method of claim 2, The thermoplastic thermal conductive resin a) 10 to 95 weight percent of thermoplastic resin, and b) 90 to 5% by weight of a ceramic solid having a thermal conductivity of at least 300 W / mK at room temperature The backlight unit of the liquid crystal display device comprising a. The method of claim 3, wherein The thermoplastic resin of a) is polybutylene terephthalate, polyethylene terephthalate, aromatic polyamide, polyamide, polycarbonate, polystyrene, polyphenylene sulfide, thermotropic liquid crystal polymer, polysulfone, polyether sulfone, polyetherimide, Polyether ether ketone, polyarylate, polymethylmethylacrylate, polyvinyl alcohol, polypropylene, polyethylene, polyacrylonitrile butadiene styrene copolymer, polytetramethylene oxide-1,4-butanediol copolymer, styrene A backlight unit of a liquid crystal display device, characterized in that at least one selected from the group consisting of a copolymer, a fluororesin, polyvinyl chloride, and polyacrylonitrile. The method of claim 3, wherein The ceramic solid of b) consists of boron nitride, silicon carbide, diamond, beryllium oxide, boron phosphide, aluminum nitride, beryllium sulfide, boron azenide, silicon, gallium nitride, aluminum phosphide, and gallium phosphide The backlight unit of the liquid crystal display device, characterized in that at least one selected from the group. The method of claim 2, And at least one filler selected from the group consisting of flakes, glass fibers, and halogens or non-halogen-based flame retardants. The method of claim 2, The thermoplastic thermally conductive resin further comprises at least one white dielectric material selected from the group consisting of BaSO ₄ , TiO ₂ , SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ . Unit. The method of claim 2, And the thermoplastic heat conductive resin is mixed and extruded in a twin screw extruder.