WO2016024747A1

WO2016024747A1 - Backlight device and display device including plastic chassis

Info

Publication number: WO2016024747A1
Application number: PCT/KR2015/008160
Authority: WO
Inventors: Eunseok Song; DoYune KIM
Original assignee: Lg Display Co., Ltd.
Priority date: 2014-08-13
Filing date: 2015-08-04
Publication date: 2016-02-18
Also published as: CN206805064U; KR102206160B1; KR20160020618A

Abstract

A plastic chassis for the backlight device is formed of resin material including glass fiber, and a UV coating layer for preventing a breakaway of the glass fiber is formed on at least one surface of the plastic chassis, and thus defects of a display device due to glass fiber foreign substance can be reduced.

Description

BACKLIGHT DEVICE AND DISPLAY DEVICE INCLUDING PLASTIC CHASSIS

The present invention relates to a backlight unit including a plastic chassis and a display device having the backlight unit. Specially, the present invention relates to a forming of an ultraviolet (UV) light coating layer on at least a portion of a surface of a plastic chassis constituting a backlight unit of a display device.

With the development of information society, various types of requirements for a display device for displaying an image are increasing and, recently, various display devices, such as a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP), and an Organic Light Emitting Diode Display Device (OLED), are being used.

Among those display devices, a Liquid Crystal Display (LCD) device includes a display panel, a driving unit and a backlight unit. The display panel includes an array substrate including a thin film transistor, which is a switching device for controlling on/off of each pixel area, an upper substrate including color filters and/or black matrixes, and a liquid crystal layer formed between the array substrate and the upper substrate. The driving unit is for controlling the thin film transistor. The backlight unit provides light to the display panel. In the LCD device, alignment of the liquid crystal layer is controlled according to an electric field applied between a common voltage (Vcom) electrode and a pixel (PXL) electrode provided at a pixel area, so as to adjust the transsmissivity of light and thereby form an image.

A backlight device providing light should be included in an LCD device. The backlight unit may include sub units such as a light source, a light guide plate, a reflecting plate, and an upper sheet. In addition, the backlight unit includes a chassis as a supporting structure for installing the sub units.

The chassis may include a plastic chassis formed of plastic material in addition to a metal chassis or a bottom chassis which supports a rear of the backlight unit.

Meanwhile, the plastic chassis may include a predetermined amount of glass fiber in resin material to improve heat resistance, strength, and the like.

In a case of a plastic chassis, in which a lot of glass fiber is contained, some of the glass fiber may protrude from a resin surface and form a burr (or other type of irregularity). In addition, in a manufacturing process of a display device, when friction or shock is applied to the plastic chassis during a transportation of the plastic chassis, some of the glass fiber may be broken away from the plastic chassis, affecting the display device as a foreign substance, and incurring a defect of the display device.

Thus, an embodiment of the present invention is proposed upon recognition of such problems, and the embodiment of the present invention is to minimize such glass fiber from acting as a foreign substance, which is included in the plastic chassis use in a backlight unit of a display device.

Based upon this background, an aspect of the present invention is to provide a backlight unit and a display device capable of minimizing breakaway of glass fiber from a plastic chassis and causing detrimental influence of the glass fiber as foreign substance, which is included in the plastic chassis used in the backlight unit of the display device.

Another aspect of the present invention is to form a UV coating layer on at least one portion of a surface of a plastic chassis for a backlight unit manufactured of plastic material including a glass fiber, in order to prevent a defect of a display device due to a glass fiber that has broken away from the surface.

According to an aspect of the present invention, a backlight device for a display device, which is combined with the rear of a display panel to emit light to the display panel, the backlight device comprises a light source, a light guide plate that guides the light from the light source, a reflecting plate that reflects the light toward the display panel, and a chassis that includes a metal chassis covering a rear of the display device, and a plastic chassis receiving the light source, the light guide plate and the reflecting plate therein, and fixed to the metal chassis. The chassis is a supporting structure. The plastic chassis is formed of plastic material, in which a glass fiber is contained, and an ultraviolet (UV) coating layer for covering a burr of the glass fiber is formed on at least a portion of a surface of the plastic chassis.

According to another aspect of the present invention, a display device comprises a display panel and a backlight device for a display device. The backlight device is combined to a rear of the display panel to emit light to the display panel. The backlight device comprises a light source, a light guide plate that guides the light from the light source, a reflecting plate that reflects the light toward the display panel, and a chassis that includes a metal chassis covering a rear of the display device, and a plastic chassis receiving the light source, the light guide plate and the reflecting plate therein, and fixed to the metal chassis. The plastic chassis is formed of plastic material, in which a glass fiber is contained, and an ultraviolet (UV) coating layer for covering a burr of the glass fiber is formed on at least a portion of the surface of the plastic chassis.

According to an embodiment of the present invention, a UV coating layer of a predetermined thickness is formed on a surface of a plastic chassis for a backlight unit of a display device. Therefore, a breakaway from a plastic chassis and a bad influence of the glass fiber as a foreign substance, which is included in the plastic chassis can be prevented.

Accordingly, a defect of a display device due to the foreign substance by the breakaway of the glass fiber from the surface of the plastic chassis for the backlight unit manufactured of plastic material including the glass fiber can be reduced.

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGs. 1A and 1B are schematic perspective views of a display device according to an embodiment of the present invention.

FIG. 2 illustrates a cross section of a display device according to an embodiment of the present invention.

FIGs. 3A and 3B illustrate a plastic chassis used in an embodiment of the present invention.

FIG. 4 is a cross sectional view of a whole of the display device.

FIG. 5 is an enlarged cross sectional view of the plastic unit.

FIG. 6 is an enlarged view of the plastic chassis of an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same elements will be designated by the same reference numerals although they are shown in different drawings. Further, in the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, terms, such as first, second, A, B, (a), (b) or the like may be used herein when describing components of the present invention. Each of these terminologies is not used to define an essence, order or sequence of a corresponding component but used merely to distinguish the corresponding component from other component(s). In the case that it is described that a certain structural element "is connected to", "is coupled to", or "is in contact with" another structural element, it should be interpreted that another structural element may "be connected to", "be coupled to", or "be in contact with" the structural elements as well as that the certain structural element is directly connected to or is in direct contact with another structural element.

FIGs. 1A and 1B are schematic perspective views of a display device according to an embodiment of the present invention. FIG. 1A is a view illustrating a display panel and a backlight unit. FIG. 1B is an exploded perspective view of the backlight unit.

The display device includes a display panel 100 and a backlight unit 200 which is installed to a rear of the display panel 100 and provides light to the display panel 100.

When the display panel 100 is a liquid crystal display panel, the display panel 100 may include an array substrate, an upper substrate and a liquid crystal material layer. The array substrate includes a plurality of gate lines, a plurality of data lines, a pixel defined on an area where the gate line and the data line intersect, and a thin film transistor which is a switching element for controlling transmittances of each pixel. The upper substrate includes a color filter, a black matrix, and/or the like. The liquid crystal material layer is placed between the array substrate and the upper substrate.

Meanwhile, a display panel to which the present invention is applied is not limited to such a liquid crystal display panel, and may be applied to all types of display panels which include a separate light source.

That is, an embodiment of the present invention may be applied to all types of display devices in which a backlight is used to provide a light source to a display panel.

Further, a display device may include a driving circuit unit, as well as the array substrate, wherein the driving circuit unit may include a timing controller (T-con), a data driver (D-IC), a gate driver (G-IC), a backlight driving unit, and a power supply unit supplying electric power to driving circuits. Further, all or a part of the driving circuit unit may be formed on the liquid crystal panel according to a Chip On Glass (COG) or a Chip On Flexible printed circuit or Chip On Film (COG) mode.

As shown in FIG. 1B, the backlight unit 200 of an embodiment of the present invention is a device for providing light to the display panel 100. The backlight unit 200 includes sub units such as a light source, a light guide plate 230 or a diffusion sheet for diffusing light to an entire area of the panel, a reflecting plate 220 for reflecting the light to the display panel, and at least one optical film 240 disposed on the light guide plate and for improving luminance, for diffusing light and for protecting the light.

The light source may use a light emitting diode, a light emitting diode strip, or the like, but is not limited thereto, and the light source may use various types of light sources which can provide light necessary for the display panel.

The light guide plate 230 may be formed as a rectangular and transparent (or clear) plastic sheet which is obtained by a die cutting, a pressing out, or an injection molding of a plastic sheet. The light from the light source such as a light emitting diode array can be emitted to an edge of the light guide plate, is total-reflected within the light guide plate, across a rear surface of the display panel, and is diffused. The light emitted through a flat upper surface of the light guide plate functions as a backlight of the display panel.

Meanwhile, at least one chassis structure (or similar frame or support) may be used as a supporting structure for installing and supporting the light source, the reflecting plate 220, the light guide plate 230, the optical film 240, and the like. The chassis (structure) may include a bottom chassis or a metal chassis 210 which may cover an entirety of the backlight unit in a rear of the backlight unit, and a plastic chassis 250 which is connected to the upper portion of the metal chassis and can have a quadrangle frame shape.

The metal chassis 210 and the plastic chassis 250 may be referred to as an m-chassis and a p-chassis, respectively. The plastic chassis 250 may be of a quadrangle frame shape having a cross section of an "L"-like shape. Of course, other cross-section configurations are possible. The plastic chassis 250 is connected to the metal chassis 210, and is used to accommodate the light source, the reflecting plate 220, the light guide plate 230, the optical film 240, and the like therein.

The display device according to an embodiment of the present invention may include the backlight unit 200, the display panel 100 on the backlight unit 200, and a cover glass 110 on the display panel.

The metal chassis 210 may be combined with the plastic chassis 250 by a combining member (or other connection means) such as a bolt 260 from a rear direction. The reflecting plate 220, the light guide plate 230 and at least one optical film 240 are sequentially stacked in the plastic chassis 250, and thus the reflecting plate 220, the light guide plate 230 and at least one optical film 240 may be received in the plastic chassis 250.

The backlight unit according to an embodiment of the present invention may be formed of two or more different pieces of material. For example, the chassis may be formed of materials of which colors are different, materials of which light-absorptions are different, materials of which surface flatness is different, materials of which light-reflections are different, materials of which densities are different, materials of which slights are different, or materials of which types are different. The particular combination of materials to be employed depend upon the type of backlight unit required with respect to various characteristics and requirements of the specific display device in which such is implemented in.

For example, the chassis for the backlight unit according to an embodiment of the present invention may include the metal chassis 210 and the plastic chassis 250. The plastic (e.g., polymer) material for the chassis may be relatively hard material such as polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS), or PC/ABS. Alternatively, the plastic (e.g., polymer) material for the chassis may be relatively soft polymer such as synthetic rubber, natural rubber, silicon, or other elastomeric material.

FIGs. 3A and 3B illustrate the plastic chassis 250 used in an embodiment of the present invention. FIG. 3A is an enlarged perspective view of the plastic chassis. FIG. 3B is a cross sectional view of the plastic chassis.

As shown in FIG. 3A, a cross section of the plastic chassis 250 used in the backlight unit may be "L" shape or "T" shape, and generally may be formed as a rectangular plastic frame. However, the rectangular frame may not be integrally formed. That is, four straight line frames may be separately formed and assembled to the metal chassis 210 of the rear direction.

Since the plastic chassis 250 is used in the backlight unit, the plastic chassis 250 is exposed to strong light and heat, and thus the plastic chassis 250 should have superior heat resistance characteristics. That is, the plastic chassis 250 is formed of material of which performance degradation by heat is not large, and a change due to heat is not large.

Therefore, the material of the plastic chassis 250 may include material in which a predetermined ratio of glass fiber is contained in polyphenylene ether (PPE) that is base material, in order to minimize deformation of the chassis by a thermal load and improve environment reliability quality.

However, the plastic material in which the glass fiber is contained has very superior characteristics with respect to heat change. However, various types of irregularities, such as minute burrs, may exist on the surface of the plastic chassis due to the glass fiber contained in the plastic chassis. In addition, there are disadvantages in which particles, burrs, or the like of the glass fiber is broken away from the surface of the chassis, enters the inside of the display device.

FIG. 3B is a cross sectional view of the plastic chassis formed of plastic material in which the glass fiber is contained.

As shown in FIG. 3B, a predetermined ratio of glass fiber 280 is contained in the polyphenylene ether (PPE) as base material. Some of the glass fiber may protrude outside the surface 252 of the plastic chassis 250 and may form a type of a glass fiber burr 280'.

As described above, when the plastic chassis is transported, moved, handled or friction (pressure) by other elements is applied to the plastic chassis in a manufacturing process or in some other situation, the glass fiber burr 280' protruding from the surface of the plastic chassis may be dislodged or separated from the plastic chassis and may result in a glass fiber foreign substance 280''.

If the glass fiber foreign substance 280'' enters into the backlight unit such as the light guide plate, a white point phenomenon in which light is brighter in an area adjacent to the foreign substance may occur, thus causing defects of the display device.

Defects caused by glass fiber foreign substances from the backlight plastic chassis makes up about 30 % or more among all types of foreign substance defects occurring in mass produced liquid crystal display devices. Thus, such glass fiber foreign substances account for a significant amount of defects.

An embodiment of the present invention is proposed based upon such problem recognition, the embodiment of the present invention forms a sufficient (predetermined) thickness of UV coating layer on a portion or a whole of a surface of a plastic chassis for a backlight unit manufactured resin material including a glass fiber in order to minimize an occurrence of glass fiber foreign substances to thus significantly and effectively reduce foreign substance defects of a display device.

FIGs. 4 and 5 are views illustrating the plastic chassis for the backlight unit according to an embodiment of the present invention. FIG. 4 is a cross sectional view of the whole display device. FIG. 5 is an enlarged cross sectional view of the plastic unit.

The backlight unit in an embodiment of the present invention is a unit combined to a rear of the display panel 100 and emitting light to the display panel. The backlight unit includes a light source (or other illumination means), a light guide plate 230 (or other guide member) that guides the light from the light source, a reflecting plate 220 (or other reflecting means) that reflects the light toward the display panel, and a chassis structure (or other support means) that includes a metal chassis 210 (or other type of relatively rigid frame having metal-like characteristics) covering a rear of the display device and a plastic chassis 250 (or other type of relatively flexible frame having plastic-like characteristics) receiving or accommodating the light source, the light guide plate and the reflecting plate therein. The plastic chassis 250 may be fixed to the metal chassis using a variety means. The chassis (structure) is a supporting structure and thus is configured with the appropriate physical properties, such as tensile strength, mechanical rigidness, heat resistance, etc. The plastic chassis 250 is formed of plastic material in which a glass fiber is contained. Different types of plastic materials (or combinations thereof) and various types of glass fiber (or similar materials) can be employed. Also, an ultraviolet (UV) coating layer (or other type of element or structures serving the same purpose) for covering irregularities (or other undesired elements) that may cause burrs or the like of the glass fiber is formed on at least a portion of a surface of the plastic chassis.

The material of the plastic chassis used in an embodiment of the present invention may be resin in which polyphenylene ether (PPE) as base material and a glass fiber having superior heat change resistant characteristics are contained in a desired (predetermined) rate. Specifically, the material of the plastic chassis may be noryl HM4025H in which a glass fiber of 39 to 41 % is contained based on polyphenylene ether (PPE). Here, it should be noted that the specific percentage amount of glass fiber inclusion can be adjusted according to the desired performance specifications, based upon characteristics of the display device in which such is implemented in. The display screen size, contents to be displayed, physical use requirements for the display device, and the like are all considerations that need to be taken into account when deciding on the glass fiber inclusion amount in view of the plastic (resin) being employed.

Since the polyphenylene ether (PPE) group resin material in which the glass fiber is contained such as the noryl HM4025H is relatively cheap and has superior heat change resistant characteristics, the polyphenylene ether (PPE) group resin material is often used as the material of the plastic chassis for the backlight unit that is exposed to large amounts of heat.

However, as described above, among the glass fiber contained in the resin material, some may protrude from the surface 252 of the plastic chassis and creates irregularities, such as burrs, particles, etc. If such glass fiber burrs dislodge from the surface and acts as a foreign substance, and the glass fiber burrs result in defects for the display device.

As shown in FIG. 5, at least one UV coating layer 320 (or other type of film serving a similar purpose) is formed on the surface of the plastic chassis 250 for the backlight unit, according to an embodiment of the present invention. In order to provide, increase or improve the necessary adhesion between the UV coating layer 320 and the target surface(s) of the plastic chassis 250, a predetermined thickness of an activator layer 310 (of other means serving the same purpose) may further employed.

The UV coating layer 320 of an embodiment of the present invention may be formed of any type of UV coating material (or other material that exhibits the desired UV related characteristics) and may be formed through any coating method (or via some other appropriate formation process). For example, the UV coating layer 320 may be formed by spreading or spraying a specific type of UV paint or a so-called UV hard paint onto the surface of glass fiber included resin mother material of the plastic chassis, or on the activator layer 310 as described in more detail below.

The UV coating layer 320 can be configured to have a thickness of about 10 to 12 microns. When the UV coating layer is formed to be less than 10 microns in thickness, the UV coating layer could be insufficient in completely covering the excessively protruded glass fiber burrs. When the UV coating layer is formed to be greater than 12 microns in thickness, the overall size (i.e., the entire thickness) of the plastic chassis undesirably changes (i.e. may be too thick) compared to when a UV coating layer is not formed. Therefore, assembly problems of the backlight unit when combining such with the metal chassis or the bottom chassis, and disadvantages in accommodating the light guide plate may occur. Thus, the UV coating layer 320 may have the thickness of about 10 to 12 microns.

For example, EP-JBE-7 by EPCAMTECH or a single UV paint by GMVT may be used as the coating material for the UV coating layer 320. The light transmittance of the UV coating layer may be 40 to 90 %, and thus may be translucent, but such transmittance is not limited thereto.

In addition, multiple UV coating materials in which the first UV coating material having a gloss and the second UV coating material having dull matte characteristics are compounded in a specific rate, may also be used as the coating material. A compound rate of the first UV coating material and the second UV coating material may be 10: 90 to 20:80 based on a weight %. However, depending upon the desired characteristics of such multiple UV coating materials, different compound rates and coating material characteristics may be employed.

For example, the UV coating material and the coating process may have the following configuration, but are not limited thereto, and as described above, in an embodiment of the present invention, any type of UV coating material and coating process may be used.

The UV coating material or a UV hard paint composite may include oligomer, photopolymerization monomer, and photopolymer. The oligomer may be included in 10 to 80 weight %, more specifically 30 to 70 weight %, based on 100 weight % of UV hard paint composite, but is not limited thereto. The oligomer may be at least one acryl group oligomer selected among a group formed of urethane acrylate, epoxy acrylate and polyester acylate.

In addition, the photopolymerization monomer in the UV coating material may be included in 10 to 80 weight %, more specifically 30 to 70 weight %, based on 100 weight % of UV hard paint composite. The photopolymerization monomer may be monofunctionalized or polyfunctionalized acrylate group monomer. The polyfunctionalized acrylate group monomer refers to a photopolymerization acrylate group monomer having two or more acrylate residues in molecules.

The photopolymer contained in the UV hard paint composite may be included in 0.1 to 30 weight %, more specifically 1 to 10 weight %, based on 100 weight % of UV hard paint composite. The type of photopolymer is not limited, and photopolymer for a short wavelength or photopolymer for a long wavelength may be selectively used as the photopolymer. The photopolymer may be of a benzophenone group, benzoin group, benzoin ether group, benzilketal group, aceto phenone group, anthraquinone group, tioxoxanthone group compound, and the like, but is not limited thereto.

An additive included in the UV hard paint composite may be included in 0.1 to 15 weight %, more specifically 0.3 to 10 weight %, and even more specifically 0.5 to 6 weight %, based on 100 weight % of UV hard paint composite, but is not limited thereto. The additive may be antifoamer, leveling agents, adherence promoter, antioxidant, light stabilizer, UV absorbent, thermal polymerization inhibitors, flatinator, diffuser, electricity charge inhibitor, plasticizer, organic charger, compound thereof, and the like. The selection of an appropriate additive is based upon a variety of factors, including the desired final characteristics of the UV hard paint composite (or UV coating material) in view of its coating application onto the chassis structure (i.e. plastic chassis, activator layer, etc.), and thus can be adjusted accordingly.

A process of forming the UV coating layer 320 may include forming a UV coating layer of a predetermined thickness by spreading or spraying UV hard paint composite onto the surface of mother material having the glass fiber configuring the plastic chassis 250 or on the activator layer 310, and a process of hardening (or curing) the UV coating layer by emitting UV rays (or other appropriate means).

In such a process, a method using UV light emission is not limited, and UV emitting devices commonly known in this field may be employed without any limit. For example, a UV lamp may be used as the UV emitting device, but is not limited thereto. An emitting time of the UV light is also not limited, and may be properly determined and adjusted such that the UV hard paint composite is sufficiently hardened or cured.

In addition, the activator layer 310 is deposited in a thickness of about 3 to 5 micron, on a surface of glass fiber included polyphenylene ether (PPE) resin mother material configuring the plastic chassis 250, and all types of spread adhesives or glue agents for improving adhesion of the UV coating layer 320 may be used on the activator layer.

For example, the material of the activator layer 310 may be a resin composite formed between the plastic chassis surface and the UV coating layer. The resin composite may be any resin capable of securing main properties of matter such as adhesion, corrosion resistance and processability. The resin composite may be at least one selected from a group formed of poly urethane resin, epoxy resin, phenoxy resin, ester resin, acryl resin, and olefin resin. Also, the resin composite may be poly urethane resin, and more specifically, the resin composite may be water soluble poly urethane resin. The selection of an appropriate resin depends on many factors, such as surface characteristics of the plastic chassis, properties of the UV coating layer, and the like.

For example, the water soluble poly urethane resin may be a type in which diisocyanate, polyol, and diamine are copolymerized, but is not limited thereto. The types of the diisocyanate, polyol, and diamine are not limited, and all compounds generally known in this field may be used.

In addition, the material of the activator layer 310 of the present specification may be a UV hard coating liquid composite of which adhesion is superior, which is formed by including fluorine group acrylate high molecules having DOPA functional group.

That is, differently from the UV coating layer using the above-mentioned materials, since the activator layer 310 is to be strongly attached to the plastic chassis surface, the activator layer 310 may be an additional UV hard coating material of which adhesion is relatively superior.

More specifically, the UV hard coating material used as the material of the activator layer 310 may include fluorine group acrylate high molecules having DOPA functional group, polyfunctional acrylate monomer, reactive acrylate oligomer, UV hard initiator, and the like. The DOPA may include an isomer such as L-DOPA, D-DOPA, DL-DOPA, and the like, and may be L-DOPA (3,4-dihydroxyphenyl-L-alanine). Meanwhile, the DOPA is a uni-molular compound, which is an element of Mussel Adhesive Proteins (MAP). The MAP are proteins having very strong adhesion, and thus the reason for the relatively strong adhesion properties of the DOPA.

However, the activator layer 310 of the present invention is not limited to the above-mentioned materials, and any material(s) deposited on the surface of the plastic chassis and also improving or at least having the necessary adhesion of the UV coating layer formed thereon may be used.

As shown in FIG. 5, in the plastic chassis 250 for the backlight unit by an embodiment of the present invention, the glass fiber burr is buried (or effectively covered) by the UV coating layer 320 and the like formed on the surface, and thus the glass fiber foreign substance hardly occurs in the subsequent manufacturing process of the display device.

FIG. 6 is an enlarged view of the plastic chassis of an embodiment of the present invention, and illustrates a case in which the UV coating layer is formed on some portion thereof.

Meanwhile, the UV coating layer 320 and/or the activator layer 310 may be formed on the entire surface of the plastic chassis 250, but alternatively may be formed on some particular portion of the surface of the plastic chassis as shown in FIG. 6.

That is, as shown in FIG. 6, among a plurality of surfaces of the plastic chassis 250 having an "L"-like shape, a possibility in which the glass fiber burr in a surface making contact with the metal chassis 210 and a surface making contact with a cover glass of the display device is comparatively low, and thus the necessity of the UV coating layer 320 and the activator layer 310 is reduced at such portions.

Therefore, the UV coating layer 320 and the activator layer 310 may be formed on at least one of a first surface 254, a second surface 256 and a third surface 258, as depicted in FIG. 6, but the particular surface need not be only limited to those shown. Here, the first surface 254 covers side surfaces of the light guide plate 230, the reflecting plate 220 and the like, and is spaced apart from the side surfaces of the light guide plate and the like. The second surface 256 makes contact with upper edges of the optical films 240 and the like, and has a portion that is not covered by a surface of the optical film. The third surface 258 covers a side surface of the display panel and is spaced apart from the side surface of the display panel.

The first surface 254, the second surface 256 and the third surface 258 are shown in detail in FIGs. 4 and 6.

A surface of the plastic chassis 250, on which the UV coating layer 320 and/or the activator layer 310 is formed is not limited the first to third surfaces, and may be changed according to an arrangement design of several elements forming the backlight unit or as needed with respect to various technical specifications and requirements.

For example, the UV coating layer 320 and/or the activator layer 310 according to an embodiment of the present invention may be formed on a surface where that not make contact with a surface of another element for a long time in an assembly process, except for a surface that directly makes contact with the surface of the other element in the assembly process.

As described above, according to an embodiment of the present invention, the predetermined thickness of a UV coating layer and/or activator layer is formed on the surface of plastic chassis for the backlight unit. Therefore, problems in which the glass fiber contained in the plastic chassis breaks away from the plastic chassis, becomes undesirable foreign substances (such as burrs), and thus causes a white spot defect and the like may be reduced.

According to one practical manufacturing application scenario, one hundred (100) display devices, each of 21.5 inches, in which a UV coating layer having the thickness of about 10 microns and an activator layer having the thickness of about 5 microns are formed on a surface of a plastic chassis were manufactured. Here, the main material of the plastic chassis is noryl HM4025H in which 39 to 41 % of glass fiber is contained based on polyphenylene ether (PPE). A plurality of white point defects occurred in the existing display device in which a UV coating layer and the like had not been included therein. However, such defects were not observed in any of the 100 display devices manufactured according to an embodiment of the present invention.

While the technical concept of the present invention has been exemplarily described with reference to the accompanying drawings, it will be understood by a person skilled in the art that the present invention may be varied and modified in various forms without departing from the scope of the present invention. Accordingly, the embodiments disclosed in the present invention are merely to not limit but describe the technical aspects of the present invention. Further, the scope of the technical concepts of the present invention is not limited by the embodiments. The scope of the present invention shall be construed on the basis of the accompanying claims in such a manner that all of the technical ideas included within the scope equivalent to the claims belong to the present invention.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2014-0105113, filed on August 13, 2014, which is hereby incorporated by reference for all purposes as if fully set forth herein.

Claims

A backlight device for a display panel, the backlight device comprising:

a light source;

a light guide plate that guides the light from the light source;

a reflecting plate that reflects the light toward the display panel; and

a chassis structure that includes a metal chassis covering a rear of the display device, and a plastic chassis that receives the light source, the light guide plate and the reflecting plate therein, and is fixed to the metal chassis, the chassis structure being a supporting structure,

wherein the plastic chassis is formed of plastic material containing glass fiber, and an ultraviolet (UV) coating layer configured to cover a burr of the glass fiber is on at least a portion of a surface of the plastic chassis.
The backlight device of claim 1, wherein the plastic material includes polyphenylene ether (PPE) as base material, and 39~41 % of the glass fiber is contained in the plastic material.
The backlight device of claim 2, further comprising an activator layer for improving an adhesion of the UV coating layer,

wherein the activator layer is between the UV coating layer and the surface of the plastic chassis.
The backlight device of claim 3, wherein the activator layer has a thickness of 3 to 5 microns, and the UV coating layer has a thickness of 10 to 12 microns.
The backlight device of claim 1, wherein the UV coating layer is on at least one of a first surface facing a side surface of the light guide plate and spaced apart from the side surface of the light guide plate, a second surface making contact with an upper edge of an optical film on the light guide plate and having a portion where a surface of the optical film does not cover, and a third surface covering a side surface of the display panel and spaced apart from the side surface of the display panel, among surfaces of the plastic chassis.
A display device comprising:

a display panel;

a backlight device combined to a rear of the display panel to emit light to the display panel comprising a light source, a light guide plate that guides the light from the light source, a reflecting plate that reflects the light toward the display panel, and a chassis structure that includes a metal chassis covering a rear of the display device, and a plastic chassis formed of a plastic material containing glass fiber receiving the light source, the light guide plate and the reflecting plate therein, and is fixed to the metal chassis; and

an ultraviolet (UV) coating layer configured to cover a burr of the glass fiber, and being on at least a portion of a surface of the plastic chassis.
The display device of claim 6, wherein the plastic material includes polyphenylene ether (PPE) as base material, and 39~41 % of the glass fiber is contained in the plastic material.
The display device of claim 7, further comprising an activator layer for improving an adhesion of the UV coating layer,

wherein the activator layer is between the UV coating layer and the surface of the plastic chassis.
The display device of claim 8, wherein the activator layer has a thickness of 3 to 5 microns, and the UV coating layer has a thickness of 10 to 12 microns.
The display device of claim 6, wherein the UV coating layer is formed on at least one of a first surface facing a side surface of the light guide plate and spaced apart from the side surface of the light guide plate, a second surface making contact with an upper edge of an optical film disposed on the light guide plate and having a portion where a surface of the optical film does not cover, and a third surface covering a side surface of the display panel and spaced apart from the side surface of the display panel, among surfaces of the plastic chassis.