KR101671513B1 - Light guide plate, and back light unit and liquid crystal display using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate capable of eliminating hot spot phenomenon and improving the uniformity of light, and a backlight unit and a liquid crystal display using the same. A light guide plate according to an exemplary embodiment of the present invention includes a light guide body for converting light incident into the light guide into plane light; And a plurality of grooves formed at a predetermined depth on the upper surface of the light guide and extending from the light-incident portion through which the light is incident to the light-entering portion opposite to the light-incident portion, and arranged at a predetermined distance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light guide plate and a backlight unit using the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate, a backlight unit and a liquid crystal display using the same, and more particularly, to a light guide plate capable of removing hot spot phenomenon and improving uniformity of light, and a backlight unit and a liquid crystal display using the same.

BACKGROUND ART [0002] Liquid crystal display devices are becoming increasingly widespread due to features such as light weight, thinness, and low power consumption driving. This liquid crystal display device is used as a portable computer such as a notebook PC, an office automation device, an audio / video device, and an indoor / outdoor advertisement display device. A transmissive liquid crystal display device that occupies most of the liquid crystal display device controls an electric field applied to the liquid crystal layer to modulate light incident from the backlight unit to display an image.

The backlight unit is roughly divided into a direct type and an edge type. The direct-type backlight unit has a structure in which a plurality of light sources are arranged in a line on a lower surface of a diffuser plate so that light can proceed directly to a front surface of a liquid crystal display device. On the other hand, the edge type backlight unit has a structure in which a light source is disposed so as to face the side face of the light guide plate and a plurality of optical films are disposed between the liquid crystal display panel and the light guide plate. In the edge type backlight unit, the light source irradiates light to one side of the light guide plate, and the light guide plate converts the light or glow emitted from the light source into planar light, thereby advancing the light to the front side of the liquid crystal display device.

Conventionally, CCFL (Cold Cathode Fluorescent Lamp), HCFL (Hot Cathode Fluorescent Lamp), EEFL (External Electrode Fluorescent Lamp) and the like have been used as the light source of the backlight unit. Recently, however, Emitting diode (hereinafter referred to as "LED") has been spotlighted due to its advantages such as high brightness and excellent contrast ratio and long lifetime.

1 is a side cross-sectional view showing a structure of a general edge type backlight unit in which an LED is used as a light source. 1, an edge type backlight comprises a light source portion including an LED housing 2 for receiving an LED 1 and a light source portion disposed adjacent to the LED 1 so that light from the LED 1 is incident on the side, A light guide plate 3 for converting the light from the LED 1 into planar light and having a diffusion pattern 3a on the lower surface for diffusing the light directed from the LED 1 to the lower surface in the upward direction, A reflection sheet 4 arranged on the lower surface of the light guide plate 3 for reflecting the light proceeding to the lower portion of the light guide plate 3 toward the upper direction of the light guide plate 3 and a light guide plate 3 disposed on the upper surface of the light guide plate 3 for improving the uniformity of light emitted from the light guide plate 3 And a cover bottom 6 to which the light source housing 2 is fixed and which supports the light guide plate 3 and the reflective sheet 4. [ On the other hand, the optical films 5 disposed on the upper side of the light guide plate 3 increase the uniformity of the light projected through the light guide plate 3 and increase the brightness by refracting and condensing the light. Specifically, the optical films 5 include a lower diffusion sheet 5a, a lower prism sheet 5b, an upper prism sheet 5c, an upper diffusion sheet 5d, and a protective sheet 5e. The lower diffusion sheet 5a serves to diffuse and emit light emitted from the light guide plate 3. On the upper surfaces of the lower and upper prism sheets 5b and 5c, triangular prism microprisms are formed with a constant arrangement. Since the micro prisms are formed to have a predetermined angle, the prism sheets 5b and 5c condense the light diffused by the lower diffusion sheet 5a in the vertical direction and emit the light. The upper diffusion sheet 5d diffuses the vertical light emitted from the upper prism sheet 5c toward the upper liquid crystal display panel and emits it, so that a uniform luminance distribution can be provided. In addition, the protective sheet 5e protects the upper diffusion sheet 5d so that the upper diffusion sheet 5d can provide a uniform luminance distribution to the liquid crystal display panel.

In order to achieve luminance uniformity of the entire backlight unit in such a configuration, an appropriate number of LEDs must be provided by suitably adjusting the interval (pitch) between the LED and the LED, and the number of optical films disposed above the light guide plate do.

However, in recent years, in order to secure the competitiveness of the display device, there have been cases where the number of the LEDs 1 as the light source is reduced or the number of the diffusion sheet and the prism sheet is reduced in order to reduce the price of the backlight unit. When the number of the LEDs is reduced, the pitch between the LED 1 and the LED 1 is increased, so that the light is concentrated on the area of the light guide plate corresponding to the part where the LED 1 is present (hereinafter, And a dark portion (hereinafter referred to as "dark portion") occurs due to lack of light in the region of the light guide plate corresponding to the portion between the LED and the LED. Figure 2 shows that in the conventional backlight unit a list is formed in the area where the LEDs 1 are arranged due to the pitch between the LEDs 1 and the LEDs 1 and the LEDs 1 and LEDs 1 1) in which the arm portions are formed.

In addition, when the number of the optical films such as the diffusion sheet and the prism sheet is reduced, the diffusion function and the light condensing function of the light are reduced, and a hot spot, which is a bright part remarkably in a specific area, is generated. The generation of the dark portion and the hot spot by the light emitted through the light guide plate adversely affects the quality of the image finally output through the display device, thereby deteriorating the image quality.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a light guide plate capable of reducing cost by preventing occurrence of hot spot phenomenon even if the number of LEDs, the diffusion sheet, and the prism sheet is reduced, Unit and a liquid crystal display device.

According to an aspect of the present invention, there is provided a light guide plate including a light guide for converting light incident into the light guide into planar light; And a plurality of grooves formed at a predetermined depth on the upper surface of the light guide and extending from the light-incident portion through which the light is incident to the light-entering portion opposite to the light-incident portion, and arranged at a predetermined distance.

Also, a backlight unit according to an embodiment of the present invention includes a light source unit including at least one light source for irradiating light; And a light guide plate for converting the light emitted from the light source into planar light, wherein the light guide plate converts light incident into the light guide plate into plane light; And a plurality of grooves formed at a predetermined depth on the upper surface of the light guide and extending from the light-incident portion through which the light is incident to the light-entering portion opposite to the light-incident portion, and arranged at a predetermined distance.

According to another aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal display panel; A plurality of light sources for generating light to be irradiated on the liquid crystal display panel; And a light guide plate for converting light emitted from the plurality of light sources into planar light, wherein the light guide plate converts light incident into the light guide plate into planar light; And a plurality of grooves formed at a predetermined depth on the upper surface of the light guide and extending from the light-incident portion through which the light is incident to the light-entering portion opposite to the light-incident portion, and arranged at a predetermined distance.

In the above configuration, the light guide plate is formed on the upper surface of the light guide, the plurality of protrusions protruding upward from both sides of the groove and formed higher than the upper surface of the light guide, and extending along the groove. And a plurality of patterns formed under the light guide plate.

The groove is formed in a V shape and has an angle range of 90 ° to 110 ° and a depth range of 1 μm to 2.5 μm and a pitch between the groove and the groove is in a range of 25 μm to 70 μm do.

The light guide plate, the backlight unit and the liquid crystal display device using the light guide plate according to the embodiment of the present invention can reduce the number of optical films by forming a plurality of grooves in the light guide plate of the edge type backlight unit or reduce the pitch between the LEDs used as a light source and the LEDs It is possible to prevent the hot spot phenomenon and achieve uniform light even if it is widened to some extent

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 3 to 10. FIG.

FIG. 3 is a perspective view illustrating a light guide plate according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line I-I 'of a perspective view of FIG. 3 and 4, a light guide plate 20 according to an embodiment of the present invention includes a light guide body 22, a light guide body 22 formed on the upper surface of the light guide body 22 to a depth smaller than the thickness of the light guide body 22, A plurality of grooves 24 extending from the light-incoming portion to which the light from the light source is incident to the return light portion on the opposite side to the light-incoming portion and formed so as to be parallel to each other with a predetermined distance (at a constant pitch) A plurality of protrusions 26 protruding upward from both sides of the groove 24 so as to be higher than the upper surface of the light guide plate and extending along the grooves 24 and formed on the bottom surface of the light guide plate 20; A plurality of patterns 28 are formed.

As the light guide 22 of the light guide plate 20, a material having a good refractive index and transmittance such as polymethylenemethacrylate (PMA), polycarbonate (PC), polyethylene (PE), cycloolefin Based resin (COP) or the like is used, but the embodiment of the present invention is not limited to these materials.

The grooves 24 of the light guide plate 20 according to the embodiment of the present invention are preferably formed in a V-shape at a certain depth from the upper surface of the light guide body 22, but the shape thereof is not limited. 4, the groove 24 is formed to have an angle alpha of 90 DEG to 110 DEG, a depth D of 1 to 2.5 mu m, and a pitch P (a distance between the groove and the groove) of 25 to 70 mu m . The height of each of the plurality of protrusions 26 is preferably smaller than the depth of the groove 24.

The patterns 28 formed on the undersurface of the light guide plate 20 are shown as spherical convex portions in the embodiment of the present invention, but they may be concave portions, and the shapes thereof are not limited.

Hereinafter, a backlight unit to which the light guide plate 20 according to the embodiment of the present invention is applied will be described.

The backlight unit according to the embodiment of the present invention includes a light source unit 10, a light guide plate 20 that converts light emitted from the light source unit 10 into planar light and outputs the light to the front surface, a light guide plate 20, A plurality of optical films 40 disposed on the upper side of the light guide plate 20 and a plurality of optical films 40 coupled with the light source unit 10 to reflect light toward the lower side of the light guide plate 20, And a cover bottom 50 for supporting the reflective sheet 30.

The light source section 10 includes an LED array 12 in which the LEDs 11 are mounted and an LED housing 13 in which the LED array 12 is received. The LEDs 11 are arranged to face the light-incoming surface of the light guide plate 20. The LED housing 13 is formed in a structure that accommodates the LED array 12 in which the LED 11 is mounted and surrounds the LED array 12 so that light does not escape to the outside.

3 and 4, the light guide plate 20 has a light guide body 22 and a light guide body 22 which is formed on the upper surface of the light guide body 22 to a depth smaller than the thickness of the light guide body 22, A plurality of grooves 24 extending from the light-incident portion to the light-incident portion on the opposite side of the light-incident portion, the grooves 24 being aligned at a constant pitch, A plurality of protrusions 26 projecting upward from the upper surface of the light guide plate and extending along the groove 24 and a plurality of patterns 28 formed on the lower surface of the light guide plate 20 do. Although the grooves 24 of the light guide plate 20 are formed in a V shape in this embodiment, the shape of the grooves 24 is not limited. 4, the groove 24 is preferably formed to have an angle alpha of 90 DEG to 110 DEG, a depth D of 1 to 2.5 mu m, and a pitch P (distance between grooves) of 25 to 70 mu m , And the height of each of the plurality of protrusions 26 is preferably formed to be smaller than the depth of the groove 24. Although the patterns 28 formed on the lower surface of the light guide plate 20 are shown as spherical convex portions in the present embodiment, they may be concave portions, and the shape of the patterns 28 is not limited.

The reflective sheet 30 is disposed under the light guide plate 20 and is incident from the LED 11 through the light entrance surface of the light guide plate 20 and travels in the downward direction of the light guide plate 20, The light is reflected to the front surface of the light guide plate 20, that is, the liquid crystal display panel, thereby enhancing the light efficiency.

The optical sheets 40 are disposed on the upper side of the light guide plate 20 to increase the uniformity of the light projected through the light guide plate 20 and increase the brightness by refracting and condensing light. Specifically, the optical sheets 40 include a diffusion sheet 41, a prism sheet 43, and a protective sheet 45. The diffusion sheet 41 diffuses the light emitted from the light guide plate 20 and supplies the light to the liquid crystal display panel. On the upper surface of the prism sheet 43, triangular prism micro prisms are formed with a constant arrangement. Since the micro prisms are formed to have a predetermined angle, the prism sheet 43 condenses the light diffused by the diffusion sheet 41 in a direction perpendicular to the surface of the upper liquid crystal display panel to provide a uniform luminance distribution . When the light guide plate 20 according to the embodiment of the present invention is used, the diffusion sheet 41 and the prism sheet 43 can be used 43 can be supplied with sufficiently uniform light. The protective sheet 45 protects the prism sheet 43, which is weak against scratching, so that the prism sheet 43 can provide a uniform luminance distribution to the liquid crystal display panel.

The cover bottom 50 includes a side wall 50a on which the LED housing 13 is installed, a first horizontal portion 50b extending from the upper end of the side wall 50a in the horizontal direction opposite to the light guide plate 20, A second horizontal portion 50d extending from the lower end of the light guide plate 20 in the horizontal direction and a guide panel (not shown) projecting upward from the first horizontal portion 50b to be described later, And a projecting portion 50e projecting upward from the second horizontal portion 50d to support the reflective sheet 30 and the light guide plate 20.

Next, a liquid crystal display device having a backlight unit to which a light guide plate 20 according to an embodiment of the present invention is applied will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a side sectional view of the liquid crystal display device having the backlight unit shown in FIG. 5, and FIG. 7 is an exploded perspective view of the liquid crystal display device shown in FIG.

6 and 7, the liquid crystal display according to the embodiment of the present invention includes the backlight unit 100 described with reference to FIG. 5, the liquid crystal display panel 60, the guide panel 70, and the case top 80 ).

Since the backlight unit has been described in detail with reference to FIG. 5, it will not be described here.

The liquid crystal display panel 60 includes a thin film transistor substrate 60a disposed on the optical sheets 40 and having a thin film transistor formed thereon, a black matrix formed in a lattice pattern opposite to the thin film transistor substrate 60a, And a color filter substrate 60b including color filters formed between the color filters 60a and 60b. The thin film transistor substrate 60a and the color filter substrate 60b are sealed with a sealant, and a liquid crystal layer is formed between these two substrates.

The guide panel 70 has an upper surface and a side surface that contact the cover and the side wall of the case tower 80. The guide panel 70 is a rectangular mold frame in which glass fiber is mixed in a synthetic resin such as polycarbonate or the like to cover one side edge and side surface of the liquid crystal display panel 60. The guide panel 70 supports the liquid crystal display panel 60 and keeps the gap between the liquid crystal display panel 60 and the optical sheets 40 constant.

The case top 80 is made of a metal material such as a galvanized steel sheet and is joined to the guide panel 70 by a hook or a screw (not shown). The case top 80 accommodates the liquid crystal display panel 60 and the backlight unit together with the cover bottom 50 and defines the effective display area of the liquid crystal display panel 60. [

8 is a view conceptually showing a path of light emitted from a light source through a light guide plate in a backlight unit to which a light guide plate 20 according to an embodiment of the present invention is applied. 8, the LED 11 as the light source is shown as being disposed below the light guide plate 20, but the light emitted from the LED 11 is not transmitted through any path between the upper surface and the lower surface of the light guide plate 20. [ And is actually disposed facing (facing) the light incidence surface. 8, among the light emitted from the LED 11 and incident on the light guide plate 20, the light reflected or diffused from the lower face of the light guide plate 20 and meeting the upper face of the light guide plate 20 at an angle smaller than a predetermined angle, Light reaching the optical sheets 40 is totally reflected on the upper surface of the light guide plate 20 and travels through the interior of the light guide plate 20 to enter the light guide plate 20, To the carry-in / minus section. Since the V-shaped groove 24 is formed on the upper surface of the light guide plate 20 according to the embodiment of the present invention, the light to be emitted through the upper surface of the light guide plate 20 is transmitted through the V- The LED 11 and the LED 11 are totally reflected and totally diffused. Also, since the oblique surface of the V-shaped groove 24 refracts the light proceeding from the lower surface and emits the light toward the upper portion of the light guide plate 20 in the vertical direction, the light collecting function of the light emitted from the light guide plate 20 is improved. 8, the solid line in the graph represents the luminance of the light emitted from the backlight unit according to the embodiment of the present invention, and the dotted line represents the luminance of the light emitted from the conventional backlight unit. When the light guide plate according to the embodiment of the present invention is employed, the brightness is improved in both the name portion and the dark portion, and the brightness is improved as compared with the conventional one as indicated by the arrow. In addition, since the luminance improvement in the dark area is larger than the luminance improvement in the bright area, it can be seen that the difference in brightness between the bright area and the dark area is reduced as compared with the conventional one.

Hereinafter, the improvement in uniformity of light achieved by the backlight unit having the light guide plate according to the present invention will be described with reference to FIGS. 9A to 11. FIG. 9A is a graph simulating the luminance of light emitted from a conventional backlight unit employing a light guide plate, FIG. 9B is a graph showing the relationship between the maximum luminance value and the minimum luminance value of light measured at a position spaced 7.2 mm from the light- FIG. 10A is a graph simulating the brightness of light emitted from the backlight unit 100 employing the light guide plate 20 according to the embodiment of the present invention. FIG. 10B is a graph showing the brightness of light emitted from the light guide plate 20, And the maximum luminance value and the minimum luminance value of the light measured at the position. FIG. 11 is a graph together with FIGS. 9B and 10B. FIG. The peaks Max of the graph having the maximum luminance value in the graphs in Figs. 9B and 10B correspond to the brightly indicated portions in the one-dot chain line in Figs. 9A and 10A, and the lower limits Min of the graph having the minimum luminance value Correspond to the darkly marked portions on the one-dot chain line in Figs. 9A and 10A. In order to evaluate the luminance uniformity of light output from the backlight unit, the Weber Fraction value was measured in the present invention. The Weber fraction represents the ratio of the average value of the maximum luminance values Max of the output light to the average value of the minimum luminance values Min and is calculated by the following equation.

W / F (Weber fraction value) = (average value of maximum luminance values) / (average value of minimum luminance values)

As can be seen from the above equation, the smaller the difference between the average value and the minimum luminance value of the maximum luminance values becomes, the smaller the Weber fraction value becomes. Thus, the smaller the Weber fraction value, the better the luminance uniformity.

Tables 1 to 3 below are tables in which Weber fraction values of light emitted from a conventional backlight unit using a light guide plate and a backlight unit using a light guide plate according to an embodiment of the present invention are measured. Table 1 compares the Weber fraction value according to the angle? Of the V-shaped groove 24 of the light guide plate 20 with the Weber fraction value according to the conventional structure. Table 2 shows the V-shaped groove 24 of the light guide plate 20 Table 3 is a table comparing the Weiber fraction value according to the depth D of the light guide plate 20 and the Weber fraction value according to the conventional structure. And a table comparing the Weber fraction value according to the conventional structure.

Conventional backlight unit A backlight unit having a light guide plate according to an embodiment of the present invention 30 ° 60 ° 90 ° 95 ° 100 ° 110 ° 120 ° 130 ° 140 ° 1.842 1.849 1.785 1.693 1.661 1.699 1.719 1.705 1.630 1.663

Conventional backlight unit A backlight unit having a light guide plate according to an embodiment of the present invention 0.5 탆 1 탆 1.5 탆 2 탆 2.5 탆 3 탆 4 탆 6 탆 8 탆 1.842 1.702 1.644 1.658 1.661 1.644 1.839 1.747 1.624 1.983

Conventional backlight unit A backlight unit having a light guide plate according to an embodiment of the present invention 10 탆 12.5 탆 16.7 탆 25 m 50 탆 70 탆 100 탆 200 탆 300 탆 1.842 2.141 2.008 1.858 1.666 1.644 1.697 1.761 1.751 1.808

As can be seen from the above Tables 1 to 3, the V-shaped groove 24 of the light guide plate 20 according to the embodiment of the present invention is formed such that the angle? Of the groove is 60 degrees or more, 24 is in the range of 0.5 탆 to 6 탆 or when the pitch P between the V-shaped groove 24 and the V-shaped groove 24 is between 25 탆 and 300 탆, the conventional light guide plate is used It can be seen that the uniformity of the output light is improved as compared with the backlight unit. However, when the angle, depth, and pitch of the V-shaped groove 20 are simultaneously applied to the light guide plate 20, the angle? Of the groove is in the range of 90 to 110 占 and the depth D is in the range of 1 占 퐉 to 2.5 占 퐉 , And the pitch P is preferably set in the range of 25 mu m to 70 mu m.

Next, referring to FIGS. 12 and 13, the effect of eliminating a hot spot, which is achieved by a backlight unit having a light guide plate according to the present invention, will be described. FIG. 12 is a view showing the state of each sheet in a conventional backlight unit using two diffuser sheets and two prism sheets as optical films and a backlight unit according to an embodiment of the present invention. In the backlight unit of the prior art, the hot spot region occurs in the upper prism sheet which is the uppermost layer in FIG. 12 (a), but in FIG. 12 (b) showing the embodiment of the present invention, It can be confirmed that the hot spot area does not occur in the area.

13 is a view showing a state of light output from a conventional backlight unit to which two composite prism sheets are applied as optical films and a backlight unit according to an embodiment of the present invention. In FIG. 13 (a) showing a conventional backlight unit, a hot spot region occurs in the upper region, but in FIG. 13 (b) illustrating the embodiment of the present invention, a hot spot region occurs in the upper region .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

1 is a side sectional view showing a conventional backlight unit.

Fig. 2 conceptually shows the path of light emitted by a light source and the brightness of light emitted from a backlight unit in a conventional backlight unit. Fig.

3 is a perspective view of a light guide plate according to an embodiment of the present invention.

4 is a cross-sectional view taken along the line I-I 'of the perspective view shown in FIG. 3;

5 is a side cross-sectional view of a backlight unit to which a light guide plate according to an embodiment of the present invention is applied.

6 is a side sectional view of a liquid crystal display device having a backlight unit shown in Fig.

7 is an exploded perspective view of the liquid crystal display shown in Fig.

8 is a view showing a path of light emitted from a light source via a light guide plate in a backlight unit to which a light guide plate according to an embodiment of the present invention is applied;

9A is a graph simulating the luminance of light emitted from a conventional backlight unit employing a light guide plate, FIG. 9B is a graph showing the relationship between the maximum luminance value and the minimum luminance value of light measured at a position spaced 7.2 mm from the light- Graph showing distribution.

10A is a graph simulating the luminance of light emitted from a backlight unit employing a light guide plate according to an embodiment of the present invention. FIG. 10B is a graph illustrating a maximum luminance value of light measured at a position 7.2 mm away from the light- And the distribution of the minimum luminance value.

FIG. 11 is a graph together with FIGS. 9B and 10B. FIG.

FIG. 12 is a view showing the state of each sheet in a conventional backlight unit to which two diffusion sheets and two prism sheets are applied as an optical film and a backlight unit according to an embodiment of the present invention; FIG.

13 is a view showing the state of light output from a conventional backlight unit to which two composite prism sheets are applied as optical films and a backlight unit according to an embodiment of the present invention.

Description of the Related Art

10: light source 11: light source

20: light guide plate 24: V-groove

30: reflective sheet 40: optical film

50: cover bottom 60: liquid crystal display panel

70: Guide panel 80: Case top

Claims (8)

A light guide for converting light incident into the light guide into plane light; A plurality of grooves formed at a predetermined depth on the upper surface of the light guide and extending from a light entrance portion through which the light is incident to a return light entrance portion opposite to the light entrance portion, And And a plurality of protrusions formed on the upper surface of the light guide and protruding upward from both left and right sides of the groove to be formed higher than the upper surface of the light guide and extending from the light entering portion to the return light portion along the groove, . The method according to claim 1, And a plurality of patterns formed on a lower portion of the light guide plate. The method according to claim 1, Wherein the groove is formed in a V-shape and has an angular range of 90 [deg.] To 110 [deg.] And a depth range of 1 [mu] m to 2.5 [mu] m. The method of claim 3, And the pitch between the groove and the groove has a range of 25 mu m to 70 mu m. A light source unit including at least one light source for irradiating light; And The backlight unit according to any one of claims 1 to 4, which converts light emitted from the light source into plane light. 6. The method of claim 5, A reflective sheet disposed below the light guide plate and reflecting light from the light source and light from the light guide plate toward the light guide plate; And At least one diffusion sheet formed on the light guide plate to diffuse and emit light emitted from the light guide plate; And Further comprising at least one prism sheet for condensing and emitting the diffused light emitted from the diffusion sheet in a vertical direction. A liquid crystal display panel; A plurality of light sources for generating light to be irradiated on the liquid crystal display panel; And The liquid crystal display device according to any one of claims 1 to 4, which converts light emitted from the plurality of light sources into plane light. 8. The method of claim 7, A guide panel for supporting the liquid crystal display panel and maintaining a constant gap between the liquid crystal display panel and the diffusion sheet and the prism sheets; And And a case top coupled to the guide panel and defining an effective display area of the liquid crystal display panel.

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