KR20070121993A - Backlight unit for big size liquid crystal display device - Google Patents

Abstract

A backlight unit of a large LCD(Liquid Crystal Display) is provided to use hot cathode fluorescent lamps as a heat source, coat a reflecting material on the outer faces of the fluorescent lamps and form a diffuser using first and second diffusion pigment layers and an UV(Ultraviolet)-shielding layer to achieve high and uniform luminance. A backlight unit of an LCD includes a reflector(226), a plurality of fluorescent lamps(218), a diffuser(224), and a plurality of optical sheets(222). The fluorescent lamps are arranged in parallel on the reflector and include an UV-absorbing material. The fluorescent lamps are hot cathode fluorescent lamps. The diffuser is mounted on the plurality of fluorescent lamps and includes first and second diffusion pigment layers(312,314). The optical sheets are formed on the diffuser.

Description

Backlight unit for big size liquid crystal display device}

1 is an exploded perspective view schematically illustrating a structure of a general liquid crystal display module.

2 is an exploded perspective view schematically showing the structure of a liquid crystal display device module according to a first embodiment of the present invention.

3 is an exploded perspective view schematically illustrating a structure of a liquid crystal display module according to a second embodiment of the present invention.

4 is a view schematically showing the structure of a diffusion plate according to the second embodiment of FIG.

5A to 5B are photographs showing simulation results of luminance of backlight units constructed in accordance with the first and second embodiments of the present invention.

FIG. 6 is a view schematically illustrating a structure of a backlight unit including the diffusion plate of FIG. 4.

7A to 7B are graphs showing the results of measuring luminance uniformity of the first and second embodiments of the present invention.

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

218: fluorescent lamp 222: optical sheet

224: diffuser plate

(310: glass substrate, 312, 314: first and second diffusion pigment layer,

316: UV blocking layer)

226: reflector

The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit of a large liquid crystal display device having high brightness and uniform brightness.

The image realization principle of a general liquid crystal display device uses the optical anisotropy and polarization property of the liquid crystal. The liquid crystal has a thin and long molecular structure and polarization in which the direction of the molecular array changes according to its size when placed in an electric field and an anisotropy having an orientation in the array. It has a nature. The liquid crystal display is an essential component of a liquid crystal panel composed of a pair of transparent insulating substrates, each having a liquid crystal layer interposed therebetween, and having a field generating electrode formed therebetween. Various images are displayed by artificially adjusting the arrangement direction of the molecules and using the light transmittance which is changed at this time.

Such a liquid crystal display device is modularized using various mechanical elements to protect the backlight unit and the liquid crystal panel and prevent light loss.

1 is an exploded perspective view schematically illustrating a structure of a general liquid crystal display device module.

As illustrated, a general liquid crystal display module includes a liquid crystal panel 10, a backlight unit 20, a support main 14, a cover bottom 16, and a top cover 12.

That is, as shown in the figure, the backlight unit 20 and the liquid crystal panel 10 are arranged in order inside the support main body 14 having a rectangular frame shape, and the support main body 14 is prevented from being deformed in shape. The cover bottom 16 is coupled along the rear surface of the main 14, and the top cover 12 surrounding the edge of the liquid crystal panel 10 is fixed to the support main 14 and the cover bottom 16 so as to fix both of them. Closely attached to and assembled.

In addition, a printed circuit board 30 connected through a flexible printed circuit board 28 is connected along at least one side of the liquid crystal panel 10, and the backlight unit 20 is connected to the backlight unit 20. Fluorescent lamps 18 arranged along the inner longitudinal direction of the support main 14 and including lamp holders (not shown) at both ends, and reflecting plates 26 of white or silver sheets interposed on the upper surface of the support main 14. ), A light guide plate 24 mounted on the reflective plate 26, and a plurality of optical sheets 22 covering the light guide plate 24.

One side of the reflecting plate 26 is provided with a lamp guide 33 for guiding the fluorescent lamp 18.

The edge type in which the fluorescent lamp 18 is installed on the side of the light guide plate 24 is mainly applied to a relatively small liquid crystal display device such as a monitor of a laptop computer and a desktop computer.

However, in recent years, as the size of the liquid crystal display increases in accordance with user demands, research into a high brightness liquid crystal display having higher light efficiency than the edge method is being actively conducted.

An object of the present invention is to provide a large liquid crystal display device having improved light efficiency.

In order to achieve the object as described above, the present invention is a reflection plate; A plurality of fluorescent lamps arranged side by side on the reflecting plate; A diffusion plate seated on the plurality of fluorescent lamps, the first and second diffusion pigment layers sequentially formed; Provided is a backlight unit for a liquid crystal display device including a plurality of optical sheets formed on the diffusion plate.

The plurality of fluorescent lamps are characterized in that the hot cathode fluorescent lamp (HCFL), each of the plurality of fluorescent lamps further comprises an ultraviolet absorbing material applied to the light emitting area toward the diffusion plate. do.

In addition, the absorbing material is characterized in that the titanium oxide (TiO ₂ ), the diffusion plate is characterized in that it comprises a glass substrate, the first diffusion pigment layer, the second diffusion pigment layer and the UV blocking layer.

In this case, the second diffusion pigment layer is characterized by being spaced apart at a predetermined interval below the first diffusion pigment layer, characterized in that the first and second diffusion pigment layers are made of the same material with the same thickness. do.

The plurality of fluorescent lamps may correspond to spaced apart regions of the second diffusion pigment layer, and the UV blocking layer may be spaced apart from an upper portion of the second diffusion pigment layer and the second diffusion pigment layer. It is characterized in that it is configured on the first diffusion layer exposed between. The UV blocking layer is positioned to face the fluorescent lamp, characterized in that composed of titanium oxide (TiO2).

In addition, the present invention cover cover; A reflection plate seated on the cover bottom; A plurality of fluorescent lamps arranged side by side on the reflective plate and coated with an absorbing material; A support side provided to fix the plurality of fluorescent lamps; A diffusion plate mounted on the plurality of fluorescent lamps, the diffusion plate including first and second diffusion pigment layers and an ultraviolet blocking layer; A plurality of optical sheets mounted on the diffusion plate; A support main bordering an edge of the diffusion plate and a plurality of optical sheets; A liquid crystal panel mounted on the optical sheet and having a printed circuit board; An edge of the liquid crystal panel is provided, and a liquid crystal display module including a top cover assembled to the support main and the cover bottom is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment

2 is an exploded perspective view schematically showing the structure of a liquid crystal display module according to a first embodiment of the present invention.

As shown, the liquid crystal display module includes a liquid crystal panel 110, a backlight unit 120, a support main 114, a cover bottom 116, and a top cover 112.

The backlight unit 120 arranges the reflective sheet 126 and the plurality of fluorescent lamps 118 side by side on the upper surface thereof, and the diffusion plate 124 and the plurality of fluorescent lamps 118 on the top. The optical sheet 122 is interposed. In this case, the plurality of fluorescent lamps 118 are fixed by a pair of side supports 132 fastened to the cover bottom 116.

Also, the backlight unit 120 and the liquid crystal panel 110 are overlapped by the top cover 112 that overlaps the liquid crystal panel 110 and surrounds the edge of the backlight unit 120 and is coupled with the cover bottom 116. To be fixed together.

At this time, the printed circuit board 130 is connected to one side of the liquid crystal panel 110 via the flexible circuit board 128 and is folded and adhered to the side or rear surface of the cover bottom 116 during the modularization process.

In this case, the plurality of fluorescent lamps 118 are three times higher in brightness than ordinary Cold Cathode Fluorescent Lamps (CCFLs) and External Electrode Fluorescent Lamps (EEFLs). It is characterized by using a hot cathode fluorescent lamp (HCFL) that is excellent for removing afterimages.

In this case, an ultraviolet absorbing material 134 such as titanium oxide (TiO ₂ ) is coated on the light emitting area of the fluorescent lamp 118 that emits light. The fluorescent lamp 118 emits strong ultraviolet light, and the ultraviolet light is absorbed by the fluorescent material to emit visible light. The luminance of the hot cathode fluorescent lamp is too high, and the diffusion plate 124 and the plurality of optical sheets. When the distance between the 122 and the fluorescent lamp 118 is close, the fluorescent lamp 118 is reflected on the screen on which an image is displayed when the LCD is driven, and the lamp spot appears to have high luminance at a specific part. This is to prevent the phenomenon because it occurs.

In addition, the diffusion plate 124 interposed on the upper portion of the fluorescent lamp 118 allows the light emitted from the plurality of fluorescent lamps 118 to propagate toward the liquid crystal panel 110 and allows light to be incident at a wide range of angles. The diffusion plate 124 is configured by sequentially forming a diffusion pigment layer 312 and a UV blocking layer 316 having a haze characteristic on the glass substrate (310 in Figure 4). .

The diffusion plate 124 is interposed on the fluorescent lamp 118 so that the ultraviolet blocking layer 316 is adjacent to the fluorescent lamp 118, the ultraviolet blocking layer 316 is a titanium oxide (TiO ₂ ) and It is formed from the same UV absorber.

The ultraviolet blocking layer 316 may cause a chemical reaction with the diffusion plate 124 interposed on the fluorescent lamp 118 due to the strong energy of the ultraviolet light emitted from the fluorescent lamp 118, and thus the diffusion plate 124. This is to prevent yellowing that turns yellow.

In addition, the UV blocking layer 316 serves to prevent the lamp stain phenomenon due to the high brightness of the fluorescent lamp 118 double.

Second Embodiment

3 is an exploded perspective view schematically illustrating a structure of a liquid crystal display module according to a second embodiment of the present invention.

As illustrated, the liquid crystal display module includes a liquid crystal panel 210, a backlight unit 220, a support main 214, a cover bottom 216, and a top cover 212.

The backlight unit 220 has a reflective sheet 226 and a plurality of fluorescent lamps 218 arranged side by side on the upper surface thereof, and the UV blocking layer 316 is formed on the plurality of fluorescent lamps 218. The plate 224 and a plurality of optical sheets 222 are interposed. In this case, the plurality of fluorescent lamps 218 are fixed by a pair of side supports 232 fastened to the cover bottom 216.

In addition, the backlight unit 220 surrounds the liquid crystal panel 210 in front of the backlight unit 220, and surrounds the edge of the backlight unit 220 and the liquid crystal panel 210 by the top cover 212 coupled with the cover bottom 216. To be fixed integrally.

At this time, the printed circuit board 230 is connected to one side of the liquid crystal panel 210 via the flexible circuit board 228, and is folded and adhered to the side or the back of the cover bottom 216 during the modularization process. A gate printed circuit board that scans and transmits an on / off signal of a thin film transistor (not shown) to a plurality of gate lines (not shown), and a source printed circuit board that transmits image signals for each frame to a plurality of data lines (not shown). The liquid crystal panel 210 is divided into two adjacent edges, respectively.

In this case, the plurality of fluorescent lamps 218 are three times higher in brightness than ordinary cold cathode fluorescent lamps and external electrode fluorescent lamps, and are characterized by using a hot cathode fluorescent lamp which is excellent for removing an afterimage of an image when a video is implemented.

In this case, a reflecting material 234 such as titanium oxide (TiO ₂ ) is coated on a light emitting area in which the exterior of the fluorescent lamp 218 emits light. This is because, since the luminance of the hot cathode fluorescent lamp is too high, when the liquid crystal display is driven, a lamp spot phenomenon occurs in which the fluorescent lamp 218 is reflected on the screen where an image is displayed and the luminance is high at a specific part. This is to prevent this.

The fluorescent lamp 218 emits strong ultraviolet light, and the ultraviolet light is absorbed by the fluorescent material to emit visible light, and the visible light is emitted by the diffuser plate 224 at a wide range of angles. After passing through the plurality of optical sheets 222 in order to enter the liquid crystal panel 210, the liquid crystal panel 210 can display an image to the outside.

In this case, the diffusion plate 224 is composed of the first and second diffusion pigment layers 312 and 314 and the UV blocking layer 316, which will be described in more detail with reference to FIG.

As shown in FIG. 4, the first and second diffusion pigment layers 312 and 314 having a haze characteristic and the UV blocking layer 316 are sequentially formed on the glass substrate 310. The diffusion plate 224 is interposed on the fluorescent lamp 218 of FIG. 3 such that the UV blocking layer 316 is adjacent to the fluorescent lamp 218 of FIG. 3.

The first diffusion pigment layer 312 is formed entirely on the glass substrate 310, the second diffusion pigment layer 314 is formed to have a predetermined interval on the first diffusion pigment layer 312. In addition, the diffusion plate 224 is formed to correspond to the area between the fluorescent lamps (218 of FIG. 3) arranged in a plurality.

The reason for using the glass substrate 310 as the base substrate of the diffusion plate 224 is a transparent acrylic resin or PMMA (polymethylmethacrylate), a thermoplastic resin PET plate, etc. In order to avoid the possibility of deformation of the shape due to the high heat generation of the hot cathode fluorescent lamp used as the light source of the present invention.

In this case, the haze characteristic is a phenomenon in which light is diffused according to the intrinsic properties of the material in addition to reflection or absorption depending on the type of material when light passes through the transparent material, and an opaque cloudy appearance appears. The lower this value, the higher the light transmittance.

Therefore, the region in which the first and second diffusion pigment layers 312 and 314 are doubled has higher haze characteristics than the region in which the second diffusion pigment layer 314 is not formed.

In addition, the UV blocking layer 316 formed on the second diffusion pigment layer 314 including the spaced apart portion of the second diffusion pigment layer 314 is formed of a reflective material such as titanium oxide (TiO ₂ ). do.

This is to prevent the yellowing phenomenon in which the diffusion plate 224 turns yellow due to the strong ultraviolet light emitted from the fluorescent lamp 218 of FIG. 3.

In addition, the lamp spot phenomenon due to the high brightness of the fluorescent lamp (218 of FIG. 3) can be prevented in triplicate, which will be described in more detail with reference to FIGS. 5A to 5B.

FIG. 5A illustrates a reflective material (134 of FIG. 2) coated on a light emitting area of the fluorescent lamp 118 and a fluorescent lamp 118 in order to prevent double lamp staining according to the first embodiment of the present invention. ) Is a result obtained by simulating the luminance when the ultraviolet blocking layer (216 of FIG. 4) is formed on one surface of the diffusion plate (124 of FIG. 2).

At this time, the right picture is a picture showing a structure in which the fluorescent lamp 118 is arranged, the left picture is a picture showing the lamp spot phenomenon in the state in which the arrangement of the fluorescent lamp 118 is excluded.

5A, it can be seen that by using the hot cathode fluorescent lamp, the lamp spot phenomenon does not disappear completely even if the lamp spot phenomenon caused by the high brightness of the fluorescent lamp 218 is prevented in two. .

In particular, when looking at the photograph in detail, it can be seen that the lamp spot phenomenon is more generated in the area between the neighboring areas of the fluorescent lamps 218 arranged in plurality.

Therefore, in FIG. 5B, as described above, the reflective material 234 of FIG. 3 is coated on the light emitting area of the fluorescent lamp 218, and corresponding to the fluorescent lamp 218, according to the second embodiment of the present invention. The UV blocking layer (316 in FIG. 3) is formed on one surface of the diffusion plate (224 in FIG. 3), and the diffusion plate (FIG. 4 in FIG. The second diffusion pigment layer (314 in FIG. 4) is further configured in the region of 224 to simulate the luminance.

As can be seen from the photograph of FIG. 5B, it can be seen that the lamp stain phenomenon disappeared completely compared to FIG. 5A.

That is, a reflective material (234 of FIG. 3), the UV blocking layer (316 of FIG. 4), and a second diffusion pigment layer (314 of FIG. 4) which apply a lamp unevenness to the light emitting area of the fluorescent lamp 218. ) To eliminate the lamp stain completely.

In this case, in order to assist in understanding a region in which the second diffusion pigment layer 314 of FIG. 4 is formed, the diffusion plate 224 of FIG. 4 and the fluorescent lamp of FIG. 4 are provided. The location of 218 is schematically illustrated.

6 is a diagram schematically illustrating a structure of a backlight unit according to a second embodiment of the present invention.

As shown, a plurality of fluorescent lamps 218 arranged side by side at a predetermined interval on the reflective plate 226, the diffusion plate 224 and a plurality of optical sheets 222 on the fluorescent lamp 218 is It is interposed.

In this case, the diffusion plate 224 includes a glass substrate 310, the first and second diffusion pigment layers 312 and 314 and the UV blocking layer 316, the second diffusion layer 314 is the neighbor It is formed spaced apart at regular intervals in the area corresponding to the inter-region A between the fluorescent lamps 218.

This is because the fluorescent lamp 218 is coated by applying a reflective material (234 of FIG. 3) to the light emitting area of the fluorescent lamp 2118 to prevent a lamp spot phenomenon caused by the high brightness of the fluorescent lamp 218. Since the light F1 emitted from the upper region corresponding to the light emission area is lower than the light F2 emitted from the upper region corresponding to the inter-region A between the adjacent fluorescent lamps 218, the fluorescent lamp This is to make the light F1 and F2 emitted at 218 have a uniform brightness.

That is, compared to the light F1 emitted from the upper region corresponding to the fluorescent lamp 218, the luminance of the light F2 emitted from the inter-area A between the adjacent fluorescent lamps 218 is higher. By further forming a second diffusion pigment layer 314 having a haze characteristic in a region corresponding to the interregion A between the fluorescent lamps 218, a region corresponding to the interregion A between the fluorescent lamps 218. Since the first and second diffusion pigment layers 312 and 314 are formed in two layers, the first and second diffusion pigment layers 312 and 314 have a double haze characteristic, thereby lowering the brightness of the light F2.

7A to 7B are graphs showing the results of measuring luminance uniformity of the first and second embodiments of the present invention.

FIG. 7A is a graph measuring luminance uniformity of a backlight unit according to a first exemplary embodiment of the present invention. The x-axis is a value representing distances of respective fluorescent lamps 218 of FIG. It is a value showing the luminance of the light (F1, F2 in FIG. 6) emitted from each of the fluorescent lamps (218 in FIG. 6).

At this time, the values are measured in the center of the longitudinal direction of the fluorescent lamp (218 in Fig. 6), the lower the y-axis value is to show a lower luminance.

Therefore, in the graph shown in FIG. 7A, it can be seen that the luminance is not uniform with distance, in particular, when the luminance is high, then decreases, and then increases and then decreases again, the plurality of fluorescent lamps (218 of FIG. 6). ) Are spaced apart at regular intervals, the area corresponding to the fluorescent lamp (218 of FIG. 6) coated with the reflective material (234 of FIG. 3) has a low luminance, and the adjacent fluorescent lamps ( It can be seen that the inter-region (A of FIG. 6) between 218 of FIG. 6 exhibits high luminance.

FIG. 7B illustrates a fluorescent lamp adjacent to a region corresponding to a fluorescent lamp (218 of FIG. 6) of the diffusion pigment layers (312 and 314 of FIG. 6) of the diffusion plate 224 of FIG. 6 according to the second exemplary embodiment of the present invention. FIG. 6 is a graph in which luminance uniformity is measured by differently configuring an area corresponding to an inter-region (A in FIG. 6) between the two regions (218 in FIG. 6). As in FIG. 7A, each of the fluorescent lamps (Fig. 6 is a value expressed by the distance, and the y-axis is a value indicating the luminance of the light (F1, F2 in FIG. 6) emitted from the respective fluorescent lamps (218 in FIG. 6).

Looking at the graph, it can be seen that it has a uniform luminance.

As described in the second embodiment of the present invention, in the configuration in which the plurality of fluorescent lamps 218 of FIG. 6 are arranged side by side, an interregion between the neighboring fluorescent lamps 218 of FIG. By further configuring the second diffusion pigment layer (314 in FIG. 6) in the region corresponding to A) in FIG. 6 to lower the luminance, the area between the adjacent fluorescent lamps (218 in FIG. 6) (A in FIG. 6). The luminance of the light (F2 in FIG. 6) transmitted in the region corresponding to the light transmitted through the region corresponding to the fluorescent lamp (218 in FIG. 6) coated with the reflective material (234 in FIG. 3) is applied to the emission area. This is because the luminance is the same as that of F1) in FIG.

This results in uniform luminance.

In addition, it is possible to completely eliminate the lamp spot phenomenon that was not removed due to the high luminance of the region (A of FIG. 6) between the adjacent fluorescent lamps (218 of FIG. 6).

As described above, a hot-cathode fluorescent lamp excellent in eliminating an afterimage of an image when a high luminance and a moving picture is implemented by the demand of a large liquid crystal display device is used, and a reflective material (FIG. 218 of FIG. 234 of 3 is applied and the diffusion plate (224 of FIG. 6) composed of the first and second diffusion pigment layers (312 and 314 of FIG. 6) and the ultraviolet blocking layer (316 of FIG. It is possible to provide a large liquid crystal display device having no defects and having uniform luminance.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, according to the present invention, a hot cathode fluorescent lamp which is excellent for removing afterimages of an image when a high luminance and a moving image is implemented as a light source is used as a light source, and a reflective material is applied to the light emitting area of the exterior of the fluorescent lamp. 2 By forming a backlight unit including a diffusion plate composed of a diffusion pigment layer and an ultraviolet blocking layer, there is no defect such as a lamp spot phenomenon due to luminance, and it is possible to provide a large liquid crystal display device having high brightness and uniform brightness. There is.

Claims (11)

A reflector; A plurality of fluorescent lamps arranged side by side on the reflecting plate; A diffusion plate seated on the plurality of fluorescent lamps, the first and second diffusion pigment layers sequentially formed; A plurality of optical sheets formed on the diffusion plate Backlight unit for a liquid crystal display device comprising a. The method of claim 1, The plurality of fluorescent lamps are hot cathode fluorescent lamps (HCFL) backlight unit for a liquid crystal display device, characterized in that. The method of claim 2, Each of the plurality of fluorescent lamps further comprises a UV absorbing material applied to the light emitting area toward the diffusion plate. The method of claim 3, wherein And the absorbing material is titanium oxide (TiO ₂ ). The method of claim 1, And the diffusion plate comprises a glass substrate, a first diffusion pigment layer, a second diffusion pigment layer, and an ultraviolet blocking layer. The method of claim 5, The second diffusion pigment layer is a backlight unit for a liquid crystal display device, characterized in that spaced apart a predetermined interval below the first diffusion pigment layer. The method of claim 5, And the first and second diffusion pigment layers are made of the same material with the same thickness. The method of claim 7, wherein And the plurality of fluorescent lamps correspond to spaced apart regions of the second diffusion pigment layer. The method of claim 5, And the UV blocking layer is formed on the first diffusion layer exposed between the second diffusion pigment layer and the second diffusion pigment layer spaced apart from each other. The method of claim 5, The ultraviolet blocking layer is positioned to face the fluorescent lamp, the backlight unit for a liquid crystal display device, characterized in that consisting of titanium oxide (TiO2). Covertum; A reflection plate seated on the cover bottom; A plurality of fluorescent lamps arranged side by side on the reflective plate and coated with an absorbing material; A support side provided to fix the plurality of fluorescent lamps; A diffusion plate mounted on the plurality of fluorescent lamps, the diffusion plate including first and second diffusion pigment layers and an ultraviolet blocking layer; A plurality of optical sheets mounted on the diffusion plate; A support main bordering an edge of the diffusion plate and a plurality of optical sheets; A liquid crystal panel mounted on the optical sheet and having a printed circuit board; The top cover which is bounded by the edge of the liquid crystal panel and assembled to the support main and cover bottom Liquid crystal display module comprising a.

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