KR100770382B1 - Light Guide Plate of Backlight unit - Google Patents

Abstract

The present invention relates to a light guide plate that can improve the uniformity of light by forming a prism protrusion in a direction parallel to the light incident surface of the light guide plate to which the downward prism sheet is applied to remove the bright lines around the light incident surface. A light guide plate of a backlight device that forms a light incident surface on which light is incident, and an upper light emitting surface on which light is emitted, wherein a bottom surface of the light guide plate is used to uniformly emit light incident from the light incident surface to an upper surface of the light guide plate at a constant angle. The prism pattern is formed in the light surface to the side of the light incident surface, the prism pattern is formed, and in the light incident surface side of the prism pattern, the prism protrusions are formed so as to be inclined toward the light incident surface while being parallel to the light incident surface in order to disperse the light concentrated on the light incident surface. It features.

In the light guide plate of the present invention, a prism protrusion having a shape parallel to the light incident surface and inclined toward the light incident surface is formed on the floor of the light incident surface side prism pattern to disperse incident light, thereby concentrating on the light exit surface around the light incident surface by the concentration of light. The uniformity of light can be improved by preventing a bright line from generating.

Backlight, LCD, Light Guide Plate, Prism, Bright Line

Description

Light Guide Plate of Backlight Unit

1 is a view showing the structure of a conventional backlight according to the prior art,

2 is a view showing a light guide plate structure of a backlight to which a prism pattern is applied according to the related art;

3 is a view showing a lower side and a side structure of a backlight LGP having a prism protrusion according to an embodiment of the present invention;

4 is a view showing an optical path of a light guide plate on which a prism protrusion is formed according to an embodiment of the present invention;

5 is a view showing a detailed structure of a light guide plate formed with a prism protrusion according to an embodiment of the present invention;

6A to 6C illustrate detailed structures of a light guide plate having prism protrusions of various shapes according to an exemplary embodiment of the present invention.

** Explanation of symbols for main parts of drawings **

10: light guide plate

11a: light incident surface 11b: light incident surface

12: light exit surface 13: prism pattern

14: prism protrusion

The present invention relates to a structure of a light guide plate of a backlight to which a downward prism sheet is applied, and more particularly, by forming a prism protrusion in a direction parallel to the incidence plane of the light guide plate to which the prism pattern is applied, thereby removing the bright lines near the incidence plane. The light guide plate structure which can improve the uniformity of is provided.

Recently, as the information society develops, the demand for display devices is increasing in various forms. Accordingly, liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD), and vacuum fluorescent display (VFD) Various flat panel display devices have been researched and developed. Here, LCD is widely used as a mobile flat panel display device because of its excellent image quality, light weight, thinness, and low power consumption, and is particularly used as a laptop, computer monitor, and TV monitor. However, LCDs do not emit light by themselves and require a separate external light source to realize high quality images. Therefore, the LCD structure further includes a backlight unit as a light source of the liquid crystal display panel in addition to the liquid crystal display panel, so that the backlight unit uniformly supplies a high brightness light source to the liquid crystal display panel, thereby realizing high quality images.

In general, a backlight of a liquid crystal display is classified into an edge-lighting and a direct-lighting backlight according to a method of disposing a light source, and as a light source, a CCFL (Cold Cathode Fluorescent Lamp), Cylindrical fluorescent lamps such as Hot Cathode Fluorescent Lamp (HCFL) and External Electrode Fluorescent Lamp (EEFL), Light Emitting Diode (LED) devices, Electro Luminescence (EL) devices and the like are used.

Due to its relatively thin thickness, the side backlight is mainly used in LCDs for thinning portable communication devices, and the direct backlight is mainly used in LCDs for large screens such as notebooks and TV monitors due to high light efficiency.

As shown in FIG. 1, the general structure of the conventional side-type backlight is a light guide plate 10, a fluorescent lamp 20, a lamp reflector 30, a reflector plate 40, and a first and second prism sheet 50. 60) and the protective sheet 70 is configured.

In the backlight of this structure, light emitted from the fluorescent lamp 20 is incident on the light guide plate 10, and the light guide plate 10 is converted into a uniform surface light source by total internal reflection, scattering and refracting the light of the fluorescent lamp incident on the light guide source. In addition, the lower reflection plate 40 reflects the light to the upper side of the light guide plate 10.

In addition, the first and second prism sheets 50 and 60 positioned on the upper side of the light guide plate 10 may concentrate and diffuse light again to improve optical characteristics such as brightness and uniformity, and thus, the liquid crystal display panel (not shown). ), It acts as a backlight.

Recently, however, the prism sheet is directly applied to the lower surface of the light guide plate of the backlight in order to be applied to a display device that is becoming lighter and thinner, thereby making the overall backlight device lighter and thinner.

The back structure of the light guide plate to which the prism sheet is applied is shown in FIG. 2, and the light guide plate 10 has a wedge that becomes thinner from the light incident surface 11a where the fluorescent lamp 20 is located to the incoming light incident surface 11b. While forming a shape, a prism pattern 13 is formed on the back side from the light incident surface to the light incident surface.

In addition, a fluorescent lamp 20 and a lamp reflector 30 are positioned on the light incident surface side of the light guide plate 10, and a prism sheet 50 and a protective sheet 70 corresponding to the first prism sheet 50 of FIG. Forms a stacked structure.

Due to this structure, the backlight is refracted and reflected by the prism pattern 13 formed on the lower surface of the light guide plate 10 by the light incident from the light incident surface 11a to the light exit surface 12 above the light guide plate. The light is emitted again by the prism sheet 50 in the vertical direction of the light exit surface.

However, in the device of the backlight having such a structure, the light of the fluorescent lamp 20 incident on the light incident surface 11a of the light guide plate 10 is refracted at the edge portion of the light incident surface 11a as shown, Reflected again by the prism pattern, relatively strong light is emitted by being concentrated near the light incident surface 11a on the light exit surface 12.

As a result, bright lines emitting light brighter than the surroundings are generated near the light incident surface on the light emitting surface bordering the lamp reflector, and the bright lines appear in the liquid crystal display panel stacked on the light guide plate as a result. Problems that lead to quality deterioration occur.

The present invention is proposed to solve the above problems, in the light guide plate structure of the backlight device, the incident light is concentrated on the light incident surface by forming a prism protrusion for changing the light path on the lower surface of the light guide plate on which the prism pattern is formed It is an object of the present invention to provide a light guide plate of a backlight device that can remove bright lines by dispersing the material to improve uniformity of light emitted from the light guide plate.

In order to achieve the above object, the present invention provides a light guide plate of a backlight device in which one side forms a light incident surface on which light is incident and an upper surface is formed on a light emitting surface, and the bottom surface of the light guide plate is incident from the light incident surface. In order to uniformly emit light at a constant angle to the upper surface of the light guide plate, a prism pattern is formed in which a floor and a valley are formed from the light incident surface to the light incident surface side, and in order to disperse the light focused on the light incident surface in the light incident surface side valley of the prism pattern. The prism protrusion is formed so as to be inclined toward the incoming light plane while being parallel to the light plane.

In the above-described configuration, the length (w) of the rows on which the protrusions are formed is a t ≤ w ≤ 10 t based on the thickness t of the light incident surface, and the height (h) of the prism protrusions is 0.05 µm. ≦ h ≦ 10 μm, and the spacing p of the prism protrusions is 5 μm ≦ p ≦ 30 μm.

In the above-described configuration, the prism protrusions are characterized by any one of a triangular or round shape, the shape of the floor is rounded on a triangle.

In the above-described configuration, the triangular prism protrusions are formed in a range of 80 ° to 120 ° of the inner angle α ₁ formed by the valleys, and the curvature radius R ₁ of the round shape prism protrusions is 5 μm to 30 μm. It is formed in the range of μm, the prism protrusion of the shape of the floor round the triangle on the triangle is the inner angle (α ₂ ) of the valley is in the range of 80 ° to 120 °, the radius of curvature of the floor (R ₂ ) is 5 ㎛ To 20 μm.

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

3 is a view showing a bottom structure and a side structure of the light guide plate of the backlight device according to an embodiment of the present invention.

Referring to FIG. 3, the light guide plate 10 is generally formed in a shape in which one side is thicker and thinner toward the other side, and the light source is positioned on one side of the thick side to be a light incident surface 11a where light is incident, and the other side is carried in. It becomes the optical surface 11b. The lower surface of the light guide plate 10 is formed with a prism pattern 13 having a shape of a floor 13a and a valley 13b, and a light incident surface () is formed on the valley 13b of each prism pattern 13 on the light incident surface 11a side. The prism protrusion 14 parallel to 11a) is formed.

Looking at this in more detail, the above-described prism pattern 13 is formed extending from the light incident surface 11a of the light guide plate 10 to the light incident surface 11b, as shown in (a), the floor 13a and the valley ( 13b). In this case, the ridges 13a of the prism pattern 13 may be formed in a round shape in order to more efficiently refract and reflect light.

The prism protrusions 14 described above are formed in the valleys 13b of the prism pattern 13 formed on the lower surface of the light guide plate, and are formed in an embossed or indented concave-convex shape in parallel with the light incident surface 11a. Further, it is formed while inclined downward as shown in (b) toward the valley 13b at the height of the ridge 13a of the prism pattern from the light incident surface 11a to the light incident surface 11b side to a predetermined distance w. . The specific shape and configuration of such prism protrusions 14 will be described later.

4 is a view showing a path of light by the light guide plate according to the embodiment of the present invention.

As shown in FIG. 4, the prism protrusions 14 formed on the light incidence surface 11a of the light guide plate 10 disperse light refracted at the edge portion of the light incidence surface 11a and back to the light exit surface 12 of the light guide plate. By refracting and reflecting, as in the conventional light guide plate, light condensation can be eliminated by concentrating light on a specific portion near the light incident surface, thereby generating a bright line.

5 is a cross-sectional view illustrating in detail a prism protrusion formed on a prism pattern on a lower surface of the light guide plate according to the exemplary embodiment of the present invention.

The prism protrusion 14 according to the embodiment of the present invention is inclined at a predetermined distance w, height h, and interval p from the light incident surface side valley 13b of the light guide plate on which the prism pattern 13 is formed. Is formed. The direction in which the light incident by the prism protrusions 14 is dispersed and refracted may be adjusted by the distance w, the height h, the interval p, etc. at which the prism protrusions 14 are formed.

Looking at the shape of the prism protrusion 14 in detail with reference to Figure 5 according to an embodiment of the present invention, the distance (w) that the prism protrusion 14 is formed along the valley of the prism pattern (13b of Figure 3) is It is formed at a distance of t to 10t (t ≦ w ≦ 10t) based on the thickness t of the light incident surface 11a, and the height h of the prism protrusions 14 is formed to be 0.05 μm to 10 μm ( 0.05 μm ≦ h ≦ 10 μm), and the interval p of the prism protrusions 14 is formed to be 5 μm to 30 μm (5 μm ≦ p ≦ 30 μm).

As shown in FIG. 4, the light incident on the light incident surface 11a is dispersed by the prism protrusions 14 formed as described above, and may be refracted to the light emitting surface 12 without showing bright lines.

On the other hand, the prism protrusions may be formed in various shapes such as triangular or round.

6A to 6C are views illustrating shapes of various prism protrusions according to an embodiment of the present invention.

6A illustrates a general shape of a prism, and the prism protrusions 14 have a triangular shape. Here, the inner angle α ₁ formed by the floor 14a of the prism protrusions 14 is preferably formed at 80 ° to 120 °.

In addition, as shown in FIG. 6B, the prism protrusions 14 may be formed in a round shape, and in this case, the radius of curvature R ₁ of the round is preferably formed in a range of 5 μm to 30 μm.

Also, as shown in FIG. 6C, the prism protrusions 14 have a structure in which the triangular floor 14a has a round shape. In this case, the inner angle α ₂ formed by the ridge 14a of the prism protrusion is formed to form 80 ° to 120 °, and the radius of curvature R ₂ of the round is preferably formed in the range of 5 μm to 20 μm.

Although the present invention has been described in detail through specific embodiments, the present invention is not limited to the above-described embodiments and variously changed by those skilled in the art to which the present invention pertains within the scope of the technical idea. Can be implemented.

As described above, the light guide plate of the backlight device of the present invention is a light guide plate of a backlight device in which a prism pattern is formed, and a prism protrusion having a shape parallel to the light incident surface and inclined toward the incoming light incident surface is formed on the floor of the light incident surface-side prism pattern. By dispersing and refracting the light, incident light is concentrated to prevent bright lines from being generated on the light exiting surface around the light incident surface, thereby improving the uniformity of light.

Claims (6)

In one side of the light guide plate of the backlight device which forms a light incident surface to which light is incident, the upper surface of the light emitting surface, The lower surface of the light guide plate In order to uniformly output the light incident from the light incident surface at a constant angle to the upper surface of the light guide plate, a prism pattern is formed in which the floor and the valley are repeatedly formed in parallel with the direction of light incident from the light incident surface toward the light incident surface side. The prism protrusions are formed on the light incident surface side valleys of the prism pattern so as to be inclined from the light incident surface side to the incident light surface side in a direction perpendicular to the direction of incident light in order to disperse the light concentrated on the light incident surface. The length w of the column on which the prism protrusions are formed is t ≦ w ≦ 10t based on the thickness t of the light incident surface, The height h of the prism protrusions is 0.05 μm ≦ h ≦ 10 μm, Light guide plate of the backlight device, characterized in that the interval (p) of the prism projections is formed to 5㎛≤p≤30㎛. delete The light guide plate of claim 1, wherein the prism protrusion is formed in one of a triangular shape, a round shape, and a shape in which the floor is rounded on the triangle. The method of claim 3, wherein the prism protrusions on the triangle is the light guide plate of the backlight apparatus, characterized in that the cabinet (α ₁₎ the bone forming is formed in a range of 80 ° to 120 °. The light guide plate of claim 3, wherein the round prism protrusion has a radius of curvature R _{1 in} a range of 5 μm to 30 μm. According to claim 3, wherein the prism protrusion of the shape of the floor round the triangle on the triangle is the inner angle (α ₂ ) of the valley is in the range of 80 ° to 120 °, the radius of curvature (R ₂ ) of the floor is 5 ㎛ to A light guide plate of a backlight device, characterized in that formed in the range of 20 ㎛.

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