KR101730181B1 - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

The present invention discloses a backlight unit and a liquid crystal display device having the same. The disclosed backlight unit of the present invention comprises: a light source; A light guide plate for converting the light incident from the light source into a planar light source and supplying the planar light source to the liquid crystal display panel; And a light shielding pattern formed on at least one corner region along the edge of the light guide plate corresponding to the non-display region of the liquid crystal display panel, including a reflection plate disposed under the light guide plate.

The backlight unit of the present invention has the effect of eliminating the defects of the light beams generated along the edges of the display area of the liquid crystal display device even when the optical sheet is removed or the diffusion sheet is removed.

Liquid crystal display, backlight, shading, light leakage, optical sheet

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME [0002]

The present invention relates to a backlight unit used in a liquid crystal display device.

2. Description of the Related Art [0002] Liquid crystal displays (LCDs) are becoming more and more widespread due to features such as light weight, thinness, and low power consumption driving. According to this trend, liquid crystal display devices are used in office automation equipment, audio / video equipment, and the like. The liquid crystal display device displays a desired image on the screen by controlling the amount of transmitted light according to a video signal applied to a plurality of control switches arranged in a matrix form.

Among them, the liquid crystal display device is most actively used in the fields of a notebook computer, a monitor, and a television (TV) due to its excellent contrast in a moving picture display and a high contrast ratio. The liquid crystal display device has a self- A separate light source is required.

As a result, a backlight unit having a lamp is disposed on the rear surface to irradiate light toward the front of the liquid crystal display panel, thereby realizing an image of brightness that can be recognized only through the backlight unit.

FIG. 1 is an exploded perspective view of a general liquid crystal display device, and FIG. 2 is an assembled cross-sectional view of a lamp region of the liquid crystal display device of FIG.

1 and 2, a general LCD module includes a liquid crystal display panel 10, a backlight unit 20, a support main body 30, a lower cover 50, and a top cover 40. The liquid crystal display panel 10 is composed of an upper substrate 10a and a lower substrate 10b, each of which plays a key role in image display, and which is adhered to each other with a liquid crystal layer interposed therebetween. A gate printed circuit board 11 for supplying a driving signal and a data printed circuit board 12 for supplying a data signal to the liquid crystal display panel 10 are connected to one edge of the liquid crystal display panel 10 have.

A backlight unit 20 is provided behind the liquid crystal display panel 10.

The backlight unit 20 includes a lamp 24 disposed along one longitudinal edge of the support main 30, a lamp housing 25 for fixing the lamp 24, A light guide plate 26 mounted on the reflector 22 and receiving a light of the lamp 24 to generate a surface light source and a plurality of optical sheets (28).

The liquid crystal display panel 10 and the backlight unit 20 are assembled on the upper and lower sides of the support main body 30 having a rectangular frame shape and then mounted on a top cover 40 and the lower cover 50 covering the back surface of the backlight unit 20, and are integrated through the support main 30.

The light emitted from the lamp 24 is incident on the light entrance portion of the light guide plate 26 and is refracted in the direction of the liquid crystal display panel 10. While passing through the plurality of optical sheets 28, And is incident on the liquid crystal display panel 10. As a result, the liquid crystal display panel 10 displays an image on the outside.

2, the upper substrate 10a of the liquid crystal display panel 10 includes a color filter (C / F) and a black matrix (BM), and the lower substrate 10b includes a TFT Thin Film Transistor (hereinafter referred to as "TFT") array layer.

An upper polarizer 70a and a lower polarizer 70b are attached to the backside of the upper substrate 10a and the lower substrate 10b, respectively. The optical sheets 28 are made up of first, second, third and fourth optical sheets 28a, 28b, 28c and 28d and are arranged adjacent to the support main 30 and corresponding to the black matrix BM A light shielding tape 45 is attached on the fourth optical sheet 28d.

The light shielding tape 45 functions to prevent light incident obliquely along the edge of the light guide plate 26 from being diverted toward the edge of the liquid crystal display panel 10 due to refraction, reflection, and scattering.

However, recently, the liquid crystal display device does not use the optical sheets 28 or uses only one or two sheets of optical sheets depending on the tendency of thinning, shortening, and downsizing. In particular, the diffusing sheet of the optical sheets 28 is removed and only the prism sheet is used.

The prism sheet has a concavo-convex structure on its surface, and the light-shielding tape 45 can not be attached. Therefore, when the optical sheets 28 are removed from the liquid crystal display device, defects of the light beams generated in the regions where the light guide plate 26 and the support main 30 are in contact with each other can not be removed.

The present invention provides a backlight unit and a liquid crystal display device having the backlight unit capable of eliminating defects of light generated along the periphery of a display area even when all the optical sheets used in the liquid crystal display are removed or only the diffusion sheet is removed There is a purpose.

The present invention also relates to a backlight unit capable of eliminating a hot spot defect occurring in a region where a light entrance portion of a light guide plate of a liquid crystal display device and a light source (a lamp or a light emitting diode) are disposed, and a liquid crystal display There is another purpose in providing.

According to an aspect of the present invention, there is provided a backlight unit including: a light source; A light guide plate for converting the light incident from the light source into a planar light source and supplying the planar light source to the liquid crystal display panel; And a light shielding pattern formed on at least one corner region along the edge of the light guide plate corresponding to the non-display region of the liquid crystal display panel, including a reflection plate disposed under the light guide plate.

The light-shielding pattern is formed on an upper surface or a lower surface along the edge of the light guide plate, the light-shielding pattern is formed to face the upper surface and the lower surface along the edge of the light guide plate with the light guide plate interposed therebetween, The pattern has a color of either white, gray or black, and the light-shielding pattern is formed directly on the light guide plate by a printing method.

Further, the liquid crystal display device of the present invention can be applied to a liquid crystal display panel; And a backlight unit for supplying light to the liquid crystal display panel, wherein the backlight unit includes a light source, a light guide plate for converting light incident from the light source into a surface light source and supplying the light to the liquid crystal display panel, And a support main body including a reflective plate for receiving the liquid crystal display panel and the backlight unit and integrally assembling the liquid crystal display panel and the backlight unit, wherein at least one or more corner areas are formed along the periphery of the light guide plate corresponding to the non-display area of the liquid crystal display panel A light shielding pattern is formed.

The backlight unit of the present invention has the effect of eliminating the defects of the light beams generated along the edges of the display area of the liquid crystal display device even when the optical sheet is removed or the diffusion sheet is removed.

The present invention has the effect of eliminating a hot spot defect occurring in a region where a light entrance portion of a light guide plate of a liquid crystal display device and a light source (lamp or light emitting diode) are disposed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

3 is an exploded perspective view showing a liquid crystal display device according to the present invention.

3, the liquid crystal display device includes a liquid crystal display panel 110, a backlight unit 120, a support main body 130, a lower cover 150, and a top cover 140.

First, the liquid crystal display panel 110 is composed of an upper substrate 110a and a lower substrate 110b, which serve as a core part of image display, and are bonded together with a liquid crystal layer interposed therebetween. A gate printed circuit board 111 for supplying a driving signal and a data printed circuit board 112 for supplying a data signal to the liquid crystal display panel 110 are connected to one edge of the liquid crystal display panel 110. The gate and data printed circuit boards 111 and 112 are brought into close contact with the side surface of the support main body 130 or the back surface of the lower cover 150 during the modularization process.

At this time, a plurality of gate lines and data lines intersect to define a pixel on the inner surface of the lower substrate 110b, which is usually referred to as a TFT substrate or an array substrate, although not explicitly shown in the drawings, A thin film transistor (TFT) is provided at each intersection and is connected in one-to-one correspondence with the transparent pixel electrode formed in each pixel.

A color filter layer of red (R), green (G), and blue (B) color, corresponding to each pixel, and a color filter layer of blue (B) A data line, and a black matrix BM for covering a non-display region such as a thin film transistor. In addition, a transparent common electrode covering these elements is provided.

Although not clearly shown in the figure, an upper and a lower alignment film (not shown) for determining the initial alignment direction of the liquid crystal is formed at the boundary between the upper and lower substrates 110a and 110b and the liquid crystal layer of the liquid crystal display panel 110 And a seal pattern is formed along the edges of the substrates 110a and 110b to prevent leakage of the liquid crystal layer filled therebetween.

At this time, the backlight unit 120 includes a lamp 124 disposed along the lengthwise direction of both sides of the support main body 130, a lamp housing 125 fixing the lamp 124, A light guide plate 126 which is mounted on the reflection plate 122 and receives the light of the lamp 124 to generate a surface light source and a plurality of optical sheets (128). In the backlight unit 120 of the present invention, the optical sheets 128 are formed only of the prism sheets from which the diffusion sheet is removed, or the number of the optical sheets included in the optical sheets 128 is three or less.

The light guide plate 126 and the liquid crystal display panel 110 are disposed in close proximity to each other so that the light guide defects generated along the display region of the liquid crystal display panel 110, It is necessary to remove defects.

The lamp housing 125 is fixed to the light guide plate 126 in the light incident portion of the light guide plate 126 and concentrates the light generated from the lamp 124 toward the light guide plate 126.

The lamp 124 may be a fluorescent lamp such as a cold cathode fluorescent lamp or an external electrode fluorescent lamp as a light source. Alternatively, in addition to such a fluorescent lamp, a light-emitting diode lamp may be used as a lamp, and a lamp housing may be omitted when a light-emitting diode lamp is used.

The light guide plate 126 of the present invention is formed such that the light shielding pattern 145 has a predetermined width along the periphery of the edge adjacent to the support main 130. That is, the light shielding pattern 145 may be formed on the upper surface or the lower surface of the light guide plate 126 along the periphery of the display area adjacent to the support main 130 when assembled.

The light-shielding pattern 145 is formed using black, white, or gray inks by a printing method or a coating method, and it functions to absorb or reflect light and block the light.

In addition, dot patterns (not shown) may be additionally formed in the adjacent region where the light-shielding pattern 145 is formed. The dot patterns have a function of further diffracting the light to be reflected or refracted so as to be diffused. That is, there is a possibility that the luminance difference greatly increases because the light is blocked in the region of the light shielding pattern 145 and light is transmitted in the display region of the liquid crystal display panel 110. Therefore, the dot patterns minimize the luminance difference and naturally change the luminance.

The light shielding pattern 145 may be formed on at least one of the four corners of the light guide plate 126.

The liquid crystal display panel 110 and the backlight unit 120 are assembled to the upper and lower sides of the support main body 130 having a rectangular frame shape and then mounted on a top cover 140 and the lower cover 150 covering the back surface of the backlight unit 120, respectively, and are integrated through the support main body 130.

FIG. 4 is an assembled cross-sectional view of a lamp region of the liquid crystal display of FIG. 3 enlarged.

Referring to FIG. 4, the upper substrate 110a of the liquid crystal display panel 110 includes a color filter layer (C / F) and a black matrix BM, and the lower substrate 110b includes a TFT array layer.

An upper polarizer 170a and a lower polarizer 170b are attached to the back surface of the upper substrate 110a and the lower substrate 110b, respectively.

The optical sheets 128 used in the backlight unit of the present invention are composed of the first and second optical sheets 128a and 128b. The first and second optical sheets 128a and 128b may be composed of a prism sheet from which the diffusion sheet is removed.

The optical sheet 128 is disposed on the light guide plate 126 and the lamp 124 and the lamp housing 125 are assembled to the support main body 130 in the light incident area of the light guide plate 126.

A reflective plate 122 is disposed on the back surface of the light guide plate 126 and the liquid crystal display panel 110 and the backlight unit and the support main body 130 are fastened by the top cover 140 and the bottom cover 150.

In particular, a light shielding pattern 145 is formed on the light guide plate 126 of the present invention to shield light spots generated along the edge of the light guide plate 126. In addition, when the light shielding pattern 145 is formed in the area of the lamp 124, it is possible to eliminate a bright line defect due to a hot spot generated in the light incident portion of the light guide plate 126.

In addition, according to the present invention, it is possible to eliminate a light leakage or a bright line defect which is incident on the support main body 130 along the edge region of the light guide plate 126 to be reflected by the inner surface of the support main body 130.

A plurality of dot patterns 146 may be additionally formed in an adjacent region where the light shielding pattern 145 is formed. This is to cause a luminance difference due to light blocking by the light blocking pattern 145 and light transmission in the display area, so that a natural luminance change occurs at the boundary between the light blocking pattern 145 and the display area.

Accordingly, in the present invention, there is an advantage in that the light leakage, the bright line, and the hot spot defect generated along the display region of the liquid crystal display device can be eliminated even if the optical sheets are reduced.

5 and 6 are views showing another embodiment of the present invention.

5 and 6, the same reference numerals as in the previous drawings denote the same components. Hereinafter, the distinguishing portions will be mainly described.

5, an upper light shielding pattern 155a and a lower light shielding pattern 155b are formed in edge areas of the light guide plate 126 in a region where the support main 130 and the lamp 124 are coupled with the light guide plate 126 Respectively. 4, shielding patterns 155a and 155b are formed on the lower surface and the upper surface of the light guide plate 126 so as to face each other with the light guide plate 126 interposed therebetween.

In addition, a plurality of dot patterns 146 may be formed in the upper light shielding plate 126 in the upper light shielding pattern 155a and the lower light shielding pattern 155b. This is to realize a natural luminance change between the black matrix area corresponding to the light shielding pattern and the display area.

The upper shielding pattern 155a is formed of a black matrix BM formed on the upper substrate 110a by light emitted from the lamp 124 and advancing obliquely upward in the incident area of the light guide plate 126. [ And the color filter layer (C / F). The light reflected by the reflection plate 122 disposed below the lower light-shielding pattern 155b is prevented from being reflected to the corner area of the light guide plate 126 to generate light leakage or bright lines.

The upper shielding pattern 155a is generated in the lamp 124 and directly passes through the upper surface of the light guide plate 126 to block light passing between the color filter layer C / F and the black matrix BM, Prevent bad spot spots.

Referring to FIG. 6, the liquid crystal display device has the same structure as that of FIG. 4, and is a thin liquid crystal display device in which all the optical sheets used in the backlight unit are removed. The depth of the step difference region of the support main body 130 where the optical sheets are seated can be reduced and the support main body 130 interposed between the region of the lamp 124 and the liquid crystal display panel 110 130 can be made much thinner than before.

As described above, according to the present invention, even when the number of optical sheets is reduced or eliminated in accordance with the trend of weight saving, miniaturization and thinning of the liquid crystal display device, defects such as bright lines, light gaps and hot spots There is an advantage to be able to.

1 is an exploded perspective view of a general liquid crystal display device.

2 is an assembled cross-sectional view of the lamp region of the liquid crystal display of FIG.

3 is an exploded perspective view showing a liquid crystal display device according to the present invention.

FIG. 4 is an assembled cross-sectional view of a lamp region of the liquid crystal display of FIG. 3 enlarged.

5 and 6 are views showing another embodiment of the present invention.

 (Description of Reference Numbers to Main Parts of the Drawings)

110: liquid crystal display panel 120: backlight unit

130: Support main 150: Lower cover

140: Top cover 110a, 110b: Upper substrate, Lower substrate

145: Shading pattern

Claims (11)

Light source; A light guide plate for converting the light incident from the light source into a planar light source and supplying the planar light source to the liquid crystal display panel; A reflection plate disposed under the light guide plate; A light shielding pattern disposed in at least one corner area along a periphery of the light guide plate corresponding to a non-display area of the liquid crystal display panel; And And a dot pattern corresponding to at least a part of the display area of the liquid crystal display panel adjacent to the light shielding pattern and disposed on the upper surface of the light guide plate, Wherein the light shielding pattern includes an upper light shielding pattern disposed on an upper surface of the light guide plate and a lower light shielding pattern disposed on a lower surface of the light guide plate, Wherein the lower shielding pattern overlaps at least a part of the reflection plate. delete The backlight unit of claim 1, wherein the upper shield pattern and the lower shield pattern are disposed to face each other with the light guide plate interposed therebetween. The backlight unit according to claim 1, wherein the light-shielding pattern has a color of white, gray, or black. The backlight unit according to claim 1, wherein the light-shielding pattern is formed directly on the light guide plate by a printing method. The backlight unit according to claim 1, further comprising one to three optical sheets disposed on the light guide plate. delete A liquid crystal display panel; A backlight unit for supplying light to the liquid crystal display panel; And And a support main body in which the liquid crystal display panel and the backlight unit are housed and integrally assembled, The backlight unit includes a light source, a light guide plate that converts light incident from the light source into a planar light source and supplies the planar light source to the liquid crystal display panel, a reflector disposed under the light guide plate, And a dot pattern corresponding to at least a part of the display area of the liquid crystal display panel adjacent to the light shielding pattern and disposed on an upper surface of the light guide plate, wherein the light shielding pattern includes at least one light shielding pattern disposed in at least one corner area along the edge of the light guide plate, , Wherein the light shielding pattern includes an upper light shielding pattern disposed on an upper surface of the light guide plate and a lower light shielding pattern disposed on a lower surface of the light guide plate, And the lower shielding pattern overlaps at least a part of the reflection plate. The liquid crystal display of claim 8, wherein the light blocking pattern is disposed to overlap with a black matrix formed along an edge of the liquid crystal display panel. The backlight unit according to claim 1, wherein the dot pattern is further disposed on a lower surface of the light guide plate. The liquid crystal display of claim 8, wherein the dot pattern is further disposed on a lower surface of the light guide plate.

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