KR20110066480A - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

PURPOSE: A backlight unit of a liquid crystal display device is provided to remove light leakage which is generated along the around the display area. CONSTITUTION: A backlight unit comprises a light source, a light guide plate(126) which supplies light after converting point light into plane light, a reflection plate(122) which is placed on the lower part of the light guide plate, and a light shielding pattern(145) which is formed on the one or more edge area along the edge part of the light guide plate corresponding to the non-display area of the liquid crystal display panel.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

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

In general, liquid crystal displays (LCDs) have tended to be gradually widened due to their light weight, thinness, and low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. The liquid crystal display device displays a desired image on a screen by adjusting a transmission amount according to image signals applied to a plurality of control switches arranged in a matrix form.

Among them, the liquid crystal display is the most active in the field of notebooks, monitors, TVs (Television), etc. because of the high contrast ratio and excellent in moving image display, the liquid crystal display device does not have a light emitting element This requires a separate light source.

As a result, a backlight unit having a lamp is provided on the rear surface to irradiate light toward the front of the liquid crystal display panel, thereby realizing an image of identifiable luminance.

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

1 and 2, a general liquid crystal display device module includes a liquid crystal display panel 10, a backlight unit 20, a support main 30, a lower cover 50, and a top cover 40. The liquid crystal display panel 10 plays a key role in image expression and is composed of upper and lower substrates 10a and 10b bonded 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.

In addition, the backlight unit 20 is provided behind the liquid crystal display panel 10.

In this case, the backlight unit 20 includes a lamp 24 disposed along a length of one side edge of the support main 30, a lamp housing 25 fixing the lamp 24, and a lower cover 50. A white or silver reflecting plate 22 seated thereon, a light guide plate 26 mounted on the reflecting plate 22 to generate a surface light source by receiving light from the lamp 24, and a plurality of optical sheets interposed thereon. And class 28.

The liquid crystal display panel 10 and the backlight unit 20 have top edges formed on the upper and lower sides of the rectangular main frame-shaped support main 30, respectively, and then cover the upper edge of the upper surface of the liquid crystal display panel 10 ( 40 and the upper and lower sides of the backlight unit 20 are respectively coupled to each other by the lower cover 50 to be integrated through the support main 30.

As a result, the light emitted from the lamp 24 is incident on the light incident portion of the light guide plate 26 and refracted in the direction of the liquid crystal display panel 10, and the uniform brightness is high quality while passing through the plurality of optical sheets 28. Is processed into the liquid crystal display panel 10. As a result, the liquid crystal display panel 10 displays an image to the outside.

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

In addition, an upper polarizing plate 70a and a lower polarizing plate 70b are attached to the rear surfaces of the upper substrate 10a and the lower substrate 10b, respectively. The optical sheet 28 is composed of first, second, third and fourth optical sheets 28a, 28b, 28c, and 28d, and is adjacent to the support main 30 and corresponding to the black matrix BM. The light shielding tape 45 is affixed on the 4th optical sheet 28d.

The light blocking tape 45 prevents light incident inclined along the edge of the light guide plate 26 from being obliquely emitted toward the edge of the liquid crystal display panel 10 by refraction, reflection, and scattering.

However, in recent years, the liquid crystal display device does not use the optical sheets 28 or only one or two optical sheets, depending on the tendency of thinning, shortening, and miniaturization. In particular, the diffusion sheet is removed from the optical sheet 28 and only the prism sheet is employed.

The prism sheet has a problem that the surface of the prism sheet has a concave-convex structure so that the light shielding tape 45 cannot be attached. For this reason, when the optical sheets 28 are removed from the liquid crystal display, the light leakage defects generated in the areas where the light guide plate 26 and the support main 30 are in contact with each other cannot be removed.

The present invention provides a backlight unit and a liquid crystal display device having the same to remove light leakage defects generated along the edge of the 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.

In addition, the present invention provides a backlight unit capable of eliminating defects of hot spots occurring in a region in which a light incident part and a light source (lamp or light emitting diode) of a light guide plate of a liquid crystal display are disposed, and a liquid crystal display device having the same. There is another purpose in providing.

The backlight unit of the present invention for solving the above problems, the light source; A light guide plate converting light incident from the light source into a surface light source and supplying the light to a liquid crystal display panel; And a light blocking pattern including a reflective plate disposed under the light guide plate and formed in at least one corner area along an edge of the light guide plate corresponding to the non-display area of the liquid crystal display panel.

The light blocking pattern may be formed on an upper surface or a lower surface along an edge of the light guide plate, and the light blocking pattern may be formed to face the light guide plate on an upper surface and a lower surface of the light guide plate. The pattern has any one color of white, gray or black, and the light shielding pattern is formed directly on the light guide plate by a printing method.

In addition, the liquid crystal display device of the present invention, 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 configured to convert light incident from the light source into a surface light source, and supply the light to the liquid crystal display panel; At least one corner area along an edge of the light guide plate corresponding to the non-display area of the liquid crystal display panel; The light shielding pattern is formed on the.

The backlight unit of the present invention has the effect of eliminating light leakage caused along the edge of the display area of the liquid crystal display even when the optical sheet or the diffusion sheet is removed.

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. 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 numbers refer to like elements throughout.

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

As shown in FIG. 3, the LCD includes a liquid crystal display panel 110, a backlight unit 120, a support main 130, a lower cover 150, and a top cover 140.

First, the liquid crystal display panel 110 is a part that plays a key role in image expression and is composed of upper and lower substrates 110a and 110b bonded to each other with a liquid crystal layer interposed therebetween. One side edge of the liquid crystal display panel 110 is connected to 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. The gate and the data printed circuit boards 111 and 112 are brought into close contact with the side of the support main 130 or the bottom of the lower cover 150 during the modularization process.

At this time, under the premise of an active matrix method, although a plurality of gate lines and data lines are intersected on the inner surface of the lower substrate 110b, which is commonly referred to as a TFT substrate or an array substrate, pixels are defined. Thin film transistors (TFTs) are provided at each intersection to be connected one-to-one with the transparent pixel electrodes formed in each pixel.

The inner surface of the substrate, called the upper substrate 110a, includes a color filter layer of red (R), green (G), and blue (B) color, and each of them, corresponding to each pixel. And a black matrix (BM) covering a non-display area such as a data line and a thin film transistor. In addition, a transparent common electrode covering them is provided.

In addition, although not clearly shown in the drawings, upper and lower substrates 110a and 110b of the liquid crystal display panel 110 and upper and lower alignment layers (not shown) for determining the initial molecular alignment direction of the liquid crystal at the boundary portion of the liquid crystal layer. ) And a seal pattern is formed along the edges of both substrates 110a and 110b to prevent leakage of the liquid crystal layer filled therebetween.

In this case, the backlight unit 120 includes a lamp 124 disposed along the longitudinal direction of both edges of the support main 130, a lamp housing 125 fixing the lamp 124, and a lower cover 150. White or silver reflector plate 122 to be seated, a light guide plate 126 that is mounted on the reflector plate 122 and receives the light of the lamp 124 to generate a surface light source and a plurality of optical sheets interposed thereon Class 128. In the backlight unit 120 of the present invention, the optical sheets 128 may be composed of only the prism sheets from which the diffusion sheet is removed, or the number of the optical sheets included in the optical sheets 128 may be 3 or less.

As a result, the light guide plate 126 and the liquid crystal display panel 110 may be disposed closer to each other than the conventional liquid crystal display device, but light leakage defects or bright lines generated around the display area of the liquid crystal display panel 110 may be reduced. It is necessary to remove the defect.

Here, the lamp housing 125 is fixed to the light guide plate 126 in the light incident part region of the light guide plate 126, and serves to concentrate the light generated by the lamp 124 toward the light guide plate 126.

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

The light guide plate 126 of the present invention is formed such that the light blocking pattern 145 has a predetermined width along an edge circumference 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 circumference of the display area adjacent to the support main 130 during assembly.

The light shielding pattern 145 is formed using black, white, or gray ink as a printing method or a coating method, which absorbs or reflects light to block the light.

Dot patterns (not shown) may be additionally formed in an adjacent area where the light blocking pattern 145 is formed. The dot patterns have a function of further crushing and diffusing the reflected or refracted light. That is, since light is blocked in the light blocking pattern 145 area and light is transmitted in the display area of the liquid crystal display panel 110, there is a possibility that a large difference in luminance occurs. Therefore, the dot patterns are intended to minimize the luminance difference so that the luminance change may occur naturally.

In addition, the light blocking 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 have top edges that are edge-assembled to the upper and lower sides of the rectangular frame-shaped support main 130, respectively, and then surround the top edge of the liquid crystal display panel 110 ( 140 and the lower cover 150 covering the rear surface of the backlight unit 120 are respectively coupled up and down to integrate the support main 130.

4 is an enlarged cross-sectional view illustrating an enlarged lamp area in the liquid crystal display of FIG. 3.

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 polarizing plate 170a and a lower polarizing plate 170b are attached to 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 first and second optical sheets 128a and 128b. The first and second optical sheets 128a and 128b may be configured as prism sheets from which the diffusion sheet is removed.

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

The reflective plate 122 is disposed on the rear surface of the light guide plate 126, and the liquid crystal display panel 110, the backlight unit, and the support main 130 are fastened by the top cover 140 and the lower cover 150.

In particular, the light shielding pattern 145 is formed on the light guide plate 126 of the present invention to block light leakage generated along the edge of the light guide plate 126. In addition, when the light blocking pattern 145 is formed in the lamp 124 region, the bright line defect caused by the hot spot generated in the light incidence region of the light guide plate 126 may be removed.

In addition, in the present invention, incident light incident on the support main 130 along the edge region of the light guide plate 126 and reflected from the inner surface of the support main 130 may remove light defects.

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

Therefore, in the present invention, even if the optical sheets are reduced, there is an advantage in that light leakage, bright lines, and hot spot defects generated along the display area circumference of the liquid crystal display device can be removed.

5 and 6 illustrate another embodiment of the present invention.

5 and 6, the same reference numerals as the reference numerals of the previous drawings refer to the same components. Hereinafter, description will be given focusing on the distinguishing parts.

Referring to FIG. 5, in the region where the support main 130, the lamp 124, and the light guide plate 126 are fastened to each other, an upper light blocking pattern 155a and a lower light blocking pattern 155b may be formed at an edge area of the light guide plate 126. Formed. Unlike in FIG. 4, light blocking patterns 155a and 155b are formed on the lower and upper surfaces of the light guide plate 126 to face each other with the light guide plate 126 interposed therebetween.

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

Accordingly, the black light blocking pattern 155a may include a black matrix BM in which light generated from the lamp 124 proceeds obliquely upward from the incident region of the light guide plate 126 on the upper substrate 110a. ) And the color filter layer C / F are prevented from being emitted. The light reflected from the reflector 122 disposed below the lower light shielding pattern 155b is reflected by the corner region of the light guide plate 126 to prevent light leakage or bright lines.

In addition, the upper light blocking pattern 155a is generated by the lamp 124 to directly pass 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, thereby hot. Prevents hot spot failures

Referring to FIG. 6, a liquid crystal display device having a structure that is the same as that of FIG. 4 and manufactured in a thin form by removing all optical sheets used in the backlight unit. The depth of the stepped region of the support main 130 on which the optical sheets are seated can be reduced, and as shown in the drawing, the support main interposed between the lamp 124 region and the liquid crystal display panel 110 ( There is an advantage that the thickness (d) of 130) can be formed much thinner than before.

As described above, in the present invention, even when the number of optical sheets is reduced or eliminated according to the trend of light weight, miniaturization, and thinning of the liquid crystal display device, bright lines, light leakage, and hot spot defects generated along the edges of the display area can be eliminated. There is an advantage to this.

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

FIG. 2 is an assembled cross-sectional view of the lamp area of the liquid crystal display of FIG. 1.

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

4 is an enlarged cross-sectional view illustrating an enlarged lamp area in the liquid crystal display of FIG. 3.

5 and 6 illustrate another embodiment of the present invention.

 (Explanation of reference numerals for the 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 (9)

Light source; A light guide plate converting light incident from the light source into a surface light source and supplying the light to a liquid crystal display panel; And  A reflection plate disposed under the light guide plate, And a light blocking pattern formed in at least one corner area along an edge of the light guide plate corresponding to the non-display area of the liquid crystal display panel. The backlight unit of claim 1, wherein the light blocking pattern is formed on an upper surface or a lower surface of the light guide plate around a periphery of an edge of the light guide plate. The backlight unit of claim 1, wherein the light blocking pattern is formed to face the light guide plate on an upper surface and a lower surface along an edge of the light guide plate. The backlight unit of claim 1, wherein the light blocking pattern has any one color of white, gray, or black. The backlight unit of claim 1, wherein the light blocking pattern is directly formed on the light guide plate by a printing method. The backlight unit of claim 1, further comprising one to three optical sheets disposed on the light guide plate. The backlight unit of claim 1, further comprising a dot pattern formed on the light guide plate adjacent to the blocking pattern to have a uniform brightness. A liquid crystal display panel; It includes a backlight unit for supplying light to the liquid crystal display panel, The backlight unit includes a light source, a light guide plate that converts light incident from the light source into a surface light source, and supplies the light to the liquid crystal display panel, and a reflector disposed below the light guide plate. It includes a support main that is housed in the liquid crystal display panel and the backlight unit is integrally assembled, And a light shielding pattern formed in at least one corner area around an edge of the light guide plate corresponding to the non-display area of the liquid crystal display panel. The liquid crystal display device of claim 8, wherein the light blocking pattern is formed to overlap the black matrix formed along a circumference of the liquid crystal display panel.

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