KR100805621B1 - Reflection plate having good thermal conductivity for backlight unit - Google Patents

Abstract

 The present invention relates to a reflector for a backlight unit used in a liquid crystal display device, and more specifically, to a reflector for reflecting light emitted from a light source to the front of a panel by applying a thermoplastic thermal conductive resin having a thermal conductivity of 0.35 W / mK or more. The present invention relates to a reflector for a backlight unit used in a liquid crystal display device, which effectively solves a heat generation problem of a unit, and has an effect of improving impact resistance, heat resistance, mechanical strength, and excellent reflectance to improve durability of a liquid crystal display device. .

Backlight Unit, Reflector, Thermal Conductive, Thermoplastic, Heat

Description

Reflector for backlight unit with excellent thermal conductivity {REFLECTION PLATE HAVING GOOD THERMAL CONDUCTIVITY FOR BACKLIGHT UNIT}

The present invention relates to a reflector for a backlight unit used in a liquid crystal display device, and more particularly, a resin of a thermoplastic thermal conductive material is applied to a reflector that reflects light from a light source to the front of the panel to effectively solve the heat generation problem of the backlight unit. The present invention relates to a reflecting plate for a backlight unit used in a liquid crystal display device that can solve the problem, and has excellent impact resistance, heat resistance, mechanical strength, and excellent reflectance, thereby improving durability of the liquid crystal display device.

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 separate light source and a backlight unit and a reflective type using external light as a light source according to the type of light source. In the case of the dual reflective type, a backlight unit is not required and power consumption is reduced. Although a lot of research is being conducted because of the small number, the brightness of the external light source is not enough, the visibility is low, and the utilization is not made sufficiently. 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.

Japanese Patent Application Laid-open No. Hei 4-239540 discloses a white polyester film as a reflector material, but in this case, there is a problem that a change in color tone due to yellowing of the reflector and a decrease in luminance are caused by heat generated from a light source.

Japanese Patent Laid-Open Nos. 2002-98811, 2002-138150, and 2001-305321 disclose techniques related to the addition of various additives and structural changes in order to improve the reflectance, transmittance, and the like of a white polyester film.

Japanese Patent Laid-Open Nos. 2002-50222 and 2002-40214 disclose a technique using a white porous polyester film to increase the reflectance of a reflective film.

Japanese Laid-Open Patent Publication Nos. 2003-145657 and 2003-121616 disclose a technique for manufacturing a reflecting plate using an ultrafine foamed polyester sheet.

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.

However, although the conventional reflector manufacturing technology mentions a method of improving the reflectance, heat resistance, impact resistance, and the like of the reflector material, it does not provide a solution to the heat generation problem of the backlight unit, and in particular, the thermoelectric material of the reflector. No attempt has been made to solve the exothermic problem by applying the conductive resin composition.

Korean Patent Laid-Open Publication No. 2004-0017718 discloses a method of applying a metallic material such as aluminum having high thermal conductivity to a lower plate of a backlight unit in order to solve the heat generation problem of the backlight unit. However, the reflective plate between the heating element and the lower plate is disclosed. This location interferes with solving the heat problem, there is a problem that the price of the product rises.

In order to solve the problems of the prior art as described above, the present invention in the manufacture of the reflector for the backlight unit used in the liquid crystal display device, a liquid crystal display device that can effectively solve the heat generation of the backlight unit by applying a resin composition excellent in thermal conductivity An object of the present invention is to provide a reflector for a backlight unit.

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 provides a backlight unit for a liquid crystal display device, the backlight unit for a liquid crystal display device, characterized in that the manufacturing using a thermoplastic thermal conductive resin having a thermal conductivity of 0.35 W / mK or more. Provide a reflector.

Since the reflector of the backlight unit is located very close to the light source lamp, it is basically effective to solve the heat problem when the reflector material has high thermal conductivity. Since the thermal conductivity of general plastics is less than 0.2 W / mK at room temperature, it is difficult to have a function to solve the heat problem through heat conduction even when used as a reflector material of the backlight unit, so that an additional heat dissipation device using a metal material having high thermal conductivity B. Special structure is needed for heat dissipation.

However, since the reflecting plate of the present invention is manufactured using a thermoplastic resin having high thermal conductivity, an excellent heat dissipation effect can be obtained through the thermal conductivity of the reflecting plate itself even without an additional heat dissipation device or a special structure or metal material.

Hereinafter, the present invention will be described in detail.

The thermoplastic thermally conductive resin is disclosed in Korean Patent No. 450229, filed by the applicant, and is excellent in workability and mechanical properties, so when applied to a reflector for a backlight unit, it is easy to manufacture and an excellent heat control effect can be obtained.

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, polyetherether Ketones, polyarylates, polymethylmethylacrylates, polyvinylalcohols, polypropylenes, polyethylenes, polyacrylonitrilebutadienestyrene copolymers and polytetramethyleneoxide-1,4-butanediol copolymers, air containing styrene At least one or more selected from the group consisting of a copolymer, a fluororesin, polyvinylidene chloride and polyacrylonitrile can be used. 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. If the thermal conductivity is less than 0.35 W / mK, the thermal conductivity through the reflecting plate is lowered, so that it is difficult to obtain a sufficient effect on the heat dissipation of the backlight unit.

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

The thermal conductivity and reflectance of the resin compositions of the following Examples and Comparative Examples and the specimens having a diameter of 10 mm and a thickness of 3 mm were measured based on the following method.

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 resin composition and the specimen was 0.38 W / mK, and the total reflectance at the 550 nm wavelength of the specimen was 93%.

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, and the total reflectance at the 550 nm wavelength of the specimen was 92%.

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, and the total reflectance at the 550 nm wavelength of the specimen was 95%.

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, and the total reflectance at the 550 nm wavelength of the specimen was 85%.

As described above, the reflector for the backlight unit of the liquid crystal display device manufactured using the thermoplastic thermally conductive resin according to the present invention is excellent in thermal conductivity and is effective in the heat generation problem generated in the lamp of the backlight unit, and impact resistance and heat resistance Excellent mechanical strength and excellent reflectance have the effect of improving the durability of the liquid crystal display device.

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 (7)

delete In the reflection plate for a backlight unit of a liquid crystal display device, As a material of the reflecting plate is manufactured using a thermoplastic thermal conductive resin having a thermal conductivity of 0.35 W / mK or more, The backlight of the liquid crystal display device, characterized in that the thermoplastic thermal conductive resin comprises 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. Reflector for the unit. The method of claim 2, 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 Reflective plate for 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 2, 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 Reflector for backlight unit of the liquid crystal display device, characterized in that at least one selected from the group. The method of claim 2, Reflector for the backlight unit of the liquid crystal display device, characterized in that the thermoplastic thermal conductive resin further comprises at least one filler selected from the group consisting of flakes, glass fibers and halogens or non-halogen 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 . Reflector for the unit. The method of claim 2, Reflecting plate for a backlight unit of a liquid crystal display device, characterized in that the thermoplastic thermal conductive resin is prepared by the step of mixing the extrusion in a twin screw extruder.