KR100838322B1 - Light guide panel comprising asymmetric front prism for lcd - Google Patents

Abstract

A light guide plate for an LED backlight unit having an asymmetric front prism is provided to use a light source of the backlight unit efficiently by optimizing viewing angle distribution according to a request of a display and remove the necessity for existing DBEF(Dual Brightness Enhancement Film) and DRPF(Diffusive Reflective Polarization Film), thereby reducing manufacturing costs and thickness and providing high brightness and good viewing angle characteristics. A body unit(300) comprises a side(301) where light is applied, and the front(303) and rear(305) for emitting the light. In the rear, a rear prism(320) having a predetermined shape is installed. An asymmetric front prism is formed in the front of the body unit. A section of the asymmetric front prism is formed in a triangle shape. One slope of the asymmetric front prism is processed as a mirror face(308) whose surface is smooth. The other slop is processed as a diffusion surface(307) whose surface is rough.

Description

LIGHT GUIDE PANEL COMPRISING ASYMMETRIC FRONT PRISM FOR LCD}

1 is an exploded perspective view showing a backlight unit of a conventional liquid crystal display device;

2A and 2B are enlarged cross-sectional views of a light guide plate for explaining a process of light generated from a light source in a light guide plate;

2D and 2E show TCO'03 standard for luminance uniformity-viewing-angle dependency,

3 is a perspective view illustrating a light guide plate for a liquid crystal display backlight unit according to an exemplary embodiment of the present invention;

4 is a side view illustrating a light guide plate for a liquid crystal display backlight unit according to an exemplary embodiment of the present invention;

5 is a side view illustrating a light guide plate for a liquid crystal display backlight unit according to another exemplary embodiment of the present invention;

6 is a side view showing a light guide plate for a liquid crystal display backlight unit according to another embodiment of the present invention;

7A to 7D are cross-sectional views illustrating embodiments of a cross-sectional shape of an asymmetric front prism.

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

300: body portion 301: side

303: front 305: rear

306: light source 310: asymmetric front prism

315: spacing plane 320: rear prism

The present invention relates to a light guide plate for a liquid crystal display device backlight unit, and more particularly, to a liquid crystal display having an asymmetric front prism capable of controlling the viewing angle and luminance at a specific position by adjusting the cross-sectional shape of the front prism of the light guide plate. A light guide plate for a device backlight unit.

In general, a liquid crystal display device refers to a device in which a liquid crystal, which is a liquid and a solid intermediate material, is injected between two glass substrates formed of electrodes to display a number or an image by applying an electric field.

Since the liquid crystal display device is not a self-luminous device, it must have a back light unit as a light source for generating light, and the light generated from the backlight unit is used in a panel unit in which liquid crystals are constantly arranged. Images are displayed while adjusting the amount of light transmitted.

1 is an exploded perspective view illustrating a backlight unit of a conventional liquid crystal display device.

However, the backlight unit 10 of the liquid crystal display device may have a direct type under which the light source is located directly below the panel 100 of the liquid crystal display device and a side portion of the liquid crystal display panel 100 according to the position of the light source that emits light. The light source may be classified into an edge type in which the light source is located. FIG. 1 illustrates an edge type.

As shown in FIG. 1, a conventional LCD backlight unit includes a light source 105, a light guide plate 110, a reflector plate 115, a diffusion sheet 120, a prism sheet 125, and a protection sheet 130.

Although the light source 105 has various kinds of light sources 105 that can be used as the first light emitting part in the liquid crystal display device, in general, the light source used in the liquid crystal display device has a low power consumption and emits very bright white light. (Cold Cathode Fluorescence Lamp) is used.

The light guide plate 110 is formed on the lower side of the LCD panel 100 and on one side of the light source 105, and converts spot light generated from the light source 105 into plane light to convert the light to the front surface. It serves to project.

A reflector plate 115 is formed on the rear surface of the light guide plate 110 and reflects light emitted from the light source 105 toward the front LCD panel 100.

The diffuser sheet 120 is formed on the upper surface of the light guide plate 110 and serves to uniformize the light emitted through the light guide plate 110.

The prism sheet 125 is used to increase brightness by refracting and condensing light that diffuses in both horizontal and vertical directions while passing through the diffusion sheet 120, thereby rapidly decreasing brightness.

The protector sheet 130 is located on the top of the prism sheet 125 to prevent scratches of the prism sheet 125, and the moire phenomenon generated when using the prism sheet 125 formed in two layers in the vertical and horizontal directions. Used to prevent effects.

And, although not shown in Figure 1, the conventional backlight unit 10 is a frame (mold frame, which serves as a case for fixing each component constituting the backlight unit 10 to form a backlight unit 10 as an integral part, It further includes a cover (back cover, lamp cover) to protect the housing and the backlight unit 10 and to serve as strength maintenance and support.

2A and 2B are enlarged cross-sectional views of a light guide plate for explaining a process of light generated in the light source 105 in the light guide plate 110.

As shown in Fig. 2A, the light source 105 is usually located at the edge of the backlight unit 10 (in the case of LCD TV, it may be located directly behind the panel). As a result, the light is not uniformly transmitted over the entire surface and the edge tends to be brighter. To prevent this, the light guide plate 110 is used. The light guide plate is usually made of a transparent acrylic resin, which is characterized by high strength and low cracking or deformation, and is light and has high visible light transmittance.

That is, the light guide plate 110 serves to cause the light source 105 to be uniformly projected on the front surface of the light guide plate 110. In fact, the light guide plate 110 may be disassembled by placing the light source on the side of the light guide plate to generate light. The surface of 110 is not uniformly bright but light can be seen concentrated at both ends. This is because the light guide plate 110 guides the light of the light source 105 to the opposite side.

Therefore, as shown in FIG. 2B, in order to cause diffuse reflection on the rear surface of the light guide plate 110 so that the entire light guide plate 110 emits light uniformly, in particular, the distance from the light source 105 is considered. Prominence and depression (113) surface having a predetermined shape is designed. As a result of the pattern processing by forming the irregularities (113), flat light having a relatively high luminance and uniformity in the entire panel of the liquid crystal display device is formed. Is obtained.

LCDs can be divided into TN (twisted nematic) and IPS (in plane switching) types according to the arrangement of liquid crystals. The former has a poor viewing angle compared to the latter, but the light transmittance is excellent, so it requires mainly front visibility. The latter has a problem that the viewing angle is superior to the former, but the luminance is lowered as a whole because of low light transmittance.

As such, depending on the environment required by the operator, the type of panel according to the arrangement of the liquid crystal, and other external factors, the liquid crystal display device needs to improve the luminance at a specific angle or to enhance the luminance at a specific position. There is a case.

Conventionally, a dual brightness enhancement film (DBEF) and a diffusive reflective polarization film (DRPF) have been used to enhance the brightness or the viewing angle in order to improve the luminance or the viewing angle. It can increase the cost of production and increase the cost of manufacturing, which can be a factor in reducing product competitiveness.

The luminance uniformity-viewing-angle dependency item of the TCO'03 standard stipulates that the uniformity of horizontal and vertical fields of view of a general display device is managed within a specific range. Indicates the measurement position defined in.

2D and 2E show the TCO'03 standard for luminance uniformity-viewing-angle dependency, and define luminance uniformity for horizontal and vertical field of view as L _H and L _V , respectively, and maintain the value below 1.7. The TCO'03 standard is a major obstacle in developing TN mode liquid crystal display devices, which have relatively limited viewing angles on the display, and the components and technologies that can adjust the viewing angles at specific positions and angles in the backlight unit for liquid crystal display devices. Development is taking place.

Therefore, it is necessary to develop a technology for reinforcing luminance and viewing angle in a liquid crystal display without using such a film member.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a light guide plate for a liquid crystal display backlight unit that can adjust visibility and a viewing angle at a specific angle at a specific position, and in particular meets the TCO'03 standard.

The present invention for solving the above technical problem is a body portion including a front side and a rear side (되는 面) for emitting the light and the side and the light incident; Provided is a light guide plate for a liquid crystal display device backlight unit having an asymmetric front prism formed on the front surface and having a triangular cross section, one side of which is processed into a smooth mirror surface, and the other side of which is processed into a rough surface.

In addition, the present invention includes a body portion including a front side and a back side to which the light is incident and the light exiting; A light guide plate for a liquid crystal display backlight unit is formed on the front surface and has a trapezoidal cross section, one side of which is processed into a smooth mirror surface, and the other side of the surface includes an asymmetric front prism that is processed into a rough surface.

Specific details of other embodiments are included in the detailed description and the accompanying drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only the present embodiments to make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In addition, the size of the components constituting the invention in the drawings are exaggerated for clarity of the specification, when any component is described as "exists inside, or is installed in connection with" other components, any of the above configuration An element may be installed in contact with the other component, or may be installed at a predetermined distance from the other component, and when installed at a distance, a third element for fixing or connecting the component to the other component The description of the means of may be omitted.

3 is a perspective view illustrating a light guide plate for a liquid crystal display backlight unit according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the LGP 30 for the LCD unit backlight unit according to the exemplary embodiment of the present invention is generally made of a transparent acrylic material having high strength, less cracking or deformation, and light weight and high visible light transmittance. And a body 300, asymmetrical front prisms 310, and a back prism 320.

The body part 300 includes a side surface 301 through which light is incident, a front surface 303 connected to the side surface 301, and facing a panel (not shown) of the liquid crystal display, and the side surface 301. And a back surface 305 connected to and facing the front surface 303.

The original dictionary meaning of the side 301 refers to the side of the object, but is defined herein as the side from which light is incident from the light source 306. Accordingly, in FIG. 3, the side surface 301 corresponds to two surfaces 301 adjacent to the light source 306.

The rear surface 305 is provided with a back prism 320 in a predetermined shape, and the longitudinal direction of the back prism 320 is preferably perpendicular to the direction in which light is emitted from the light source 306 (the Q direction). This is because the back prism 320 should be formed to be perpendicular to the direction Q of the light emitted from the light source 306 so that diffraction, refraction, and diffusion of light can occur properly. The set of back prisms 320 may form a predetermined dot pattern or a stripe pattern.

The front surface 303 has a predetermined cross-sectional shape and asymmetrical front prisms 310 are formed to uniformly diffract, refract, and diffuse the light emitted through the body 300.

The asymmetrical front prisms 310 are formed over the entire surface 303 at regular intervals, and the asymmetrical front prisms 310 have a Q-direction in which light is emitted from a light source in FIG. 3. It is formed so that it may become the longitudinal direction of 310. As shown in FIG.

Unlike the general prism structure, the asymmetrical front prisms 310 are diffused surfaces 307 whose one surface is roughly processed, and the other surfaces are mirror surfaces 308, which are smoothly processed. It means a surface or a smooth surface, which has the latter meaning in this specification).

Here, the mirror surface 308 is a level of surface roughness corresponding to the polishing finish of the KS standard, it is preferable to have a surface roughness of less than 0.2㎛ Ra value, the diffusion surface 307 is a surface roughness corresponding to the normal finishing of the KS standard. It is preferable that the Ra value has a surface roughness of 6.3 µm or more.

In the present invention, the Ra values of the mirror surface 308 and the diffusion surface 307 were recommended as 0.2 μm and 6.3 μm, respectively, by quoting the KS standard specifically defined for the surface roughness, but in the experiment for the present invention, the mirror surface 308 was used. In the case where both the Ra value of the diffusion surface 307 is about 0.2 μm, the L _H value of TCO'03 is about 1.9 and the Ra value of the diffusion surface 307 is about 5 μm. L _H value of TCO'03 was about 1.7.

When the Ra value of the diffusion surface 307 was about 10 mu m, the L _H value of TCO'03 was about 1.4. In other words, when the Ra value of the diffusion surface 307 is 5 μm or less, the effect of improving the TCO'03 luminance uniformity-angle dependence is not large, and in this case, it is also included in the TCO'03 standard. However, it is preferable to increase the Ra value of the diffusion surface 307 as much as possible in order to obtain a further improvement effect.

4 is a side view illustrating a light guide plate for a liquid crystal display backlight unit according to an exemplary embodiment of the present invention.

As shown, the asymmetrical front prisms 310 are arranged such that the mirror surface 308 of the prism faces the left / right side 301 of the light guide plate and the diffusion surface 307 of the prism faces the center of the light guide plate. This is to improve the visibility characteristics to meet the TCO'03 standard by improving the side visibility.

That is, the light emitted from the body 300 is diffracted, refracted, and diffused in a direction inclined to the panel (not shown) of the liquid crystal display device facing the light guide plate 30 by the asymmetrical front prisms 310. By forming the left and right slopes of the asymmetric front prism 310 to have optically different surface characteristics, the mirror surface 308 of such a prism plays an optical role of a general prism, and the diffuse surface of the prism ( 307 is to further increase the uniformity of light reaching the panel (not shown) of the liquid crystal display by adding a diffusion function to the optical role of the general prism.

In FIG. 4, the longitudinal cross-sections of the asymmetrical front prisms 310 have an asymmetric triangle shape, and the mirror surfaces 308 of the prism are disposed to face left and right sides of the light guide plate 30 in opposite directions. However, this arrangement is intended to create a field of view that best fits the TCO'03 standard and may be arranged so that the diffusion surface 307 of the prism faces the left and right sides 301 of the light guide plate 30. Do.

5 is a side view illustrating a light guide plate for a liquid crystal display backlight unit according to another exemplary embodiment of the present invention.

In contrast to the embodiment of FIG. 4, in the embodiment of FIG. 5, the mirror surface 308 is disposed to face the center of the light guide plate. This arrangement improves visibility from the front. Depending on the display device, it may be necessary to arrange as shown in FIG. 4 to improve the visibility of the side surface, and sometimes it may be necessary to arrange as shown in FIG. 5 to improve the front visibility.

6 is a side view illustrating a light guide plate for a liquid crystal display backlight unit according to another exemplary embodiment of the present invention.

As shown in the drawing, a space between the mountains of the prism and the mountains is also provided so that light travels perpendicularly to the panel (not shown) of the liquid crystal display device through the space plane 315 generated by the space. It may also increase the uniformity of the light reaching the panel (not shown).

3 to 6 illustrate a case in which the longitudinal cross-sectional shapes of the asymmetrical front prisms 310 are asymmetrical triangles, the present invention is not limited thereto, and the vertical cross-sectional shape may have a trapezoidal shape. It may have a reverse groove shape having a pointed and side surface with a predetermined radius of curvature.

7A-7D illustrate embodiments of the planar shape of the asymmetric front prism 310.

As shown in FIGS. 7A to 7B, the asymmetrical front prisms 310 have a triangular shape, and an angle θ1 + θ2 of a vertex, which is a vertex, has a range of 40 ° to 140 °. In FIG. 7A, the angles θ1 and θ2 have different values, and in FIG. 7B, the angles θ1 and θ2 have the same angle, so that the cross-sectional shape is an isosceles triangle.

As illustrated in FIGS. 7C to 7D, the asymmetrical front prisms 310 have a trapezoidal shape, and FIGS. Θ1 and θ2 have a range of 20 ° to 70 °, respectively. In the case of FIG. 7C, the angles θ1 and θ2 have different values, and in FIG. 7D, the angles θ1 and θ2 have the same angle, so that the cross-sectional shape is an equilateral trapezoidal shape.

As such, the shape of the asymmetrical front prism 310 may be modified in various forms.

When the asymmetric front prism 310 is formed in a trapezoidal shape as shown in FIGS. 7C to 7D, it is preferable to set the ratio of the short side a and the long side b parallel to each other to 0.5 or less. When the shape of the asymmetrical front prism 310 has a trapezoidal shape, the ratio of the short side (a) to the long side (b) as described above is large when the ratio of the plane is too large when the ratio is greater than 0.5. It is not preferable because a problem of deterioration of luminance occurs.

 According to the light guide plate for the liquid crystal display device backlight unit according to the present invention, not only the light source of the backlight unit can be efficiently used by optimizing the viewing angle distribution according to the display's demand, but also it does not require DBEF and DRPF, which are conventionally used. It is possible to manufacture a light guide plate that can be inexpensive and thin, but can have high brightness and good viewing angle characteristics, and in particular, it can satisfy wide viewing angle characteristics that meet the TCO '03 standard.

Claims (10)

A body part including a front side and a rear side of which light is incident and a front side and a rear side which emit light; The light guide plate for a liquid crystal display device backlight unit is formed on the front surface is a triangular cross-section, one side of the surface is processed into a smooth mirror surface, the other side is asymmetric front prism processed into a rough surface diffused surface. A body part including a front side and a rear side of which light is incident and a front side and a rear side which emit light; The light guide plate for the liquid crystal display device backlight unit is formed on the front surface is a trapezoidal cross-section, one surface is processed into a smooth mirror surface, the other surface is asymmetric front prism processed into a rough surface diffused surface. The method according to claim 1 or 2, The asymmetric front prism is a light guide plate for a liquid crystal display device backlight unit, characterized in that the mirror surface is disposed toward the center of the light guide plate. The method according to claim 1 or 2, The asymmetric front prism is a light guide plate for a liquid crystal display backlight unit, characterized in that the diffusion surface is disposed toward the center of the light guide plate. The method of claim 1, The asymmetric front prism is a light guide plate for a liquid crystal display device backlight unit, characterized in that the cross-sectional shape is an isosceles triangle. The method of claim 2, The asymmetric front prism is a light guide plate for a liquid crystal display device backlight unit, characterized in that the cross-sectional shape is a trapezoidal shape. The method according to claim 1 or 5, Light guide plate for a liquid crystal display device backlight unit, characterized in that the vertex angle of the asymmetric front prism is in the range of 40 ~ 140 °. The method according to claim 2 or 6, Light guide plate for a liquid crystal display device backlight unit, characterized in that the angle (θ1, θ2) formed by each slope of the asymmetric front prism with respect to the line perpendicular to the base. The method according to claim 1 or 2, A light guide plate for a liquid crystal display device backlight unit, characterized in that the spaced apart between the asymmetrical front prism with a predetermined spacing interval between the asymmetrical front prism. The method of claim 2, The ratio of the length of the short side (a) and the long side (b) of the asymmetrical front prism is 0.5 or less, the light guide plate for a liquid crystal display device.

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