KR102194530B1 - Light guide plate having partially wedge portion and liquid cyrstal display device having thereof - Google Patents

Abstract

The present invention relates to a light guide plate for outputting uniform light with increased luminance, comprising: a light guide plate main body for guiding input light and outputting light through an upper surface; And a plurality of light collecting patterns formed on the lower surface of the light guide plate body and having a rounded upper surface in a wedge shape to condense and reflect incident light in a specific direction.

Description

Partial wedge light guide plate and liquid crystal display device having the same {LIGHT GUIDE PLATE HAVING PARTIALLY WEDGE PORTION AND LIQUID CYRSTAL DISPLAY DEVICE HAVING THEREOF}

The present invention relates to a light guide plate and a liquid crystal display device having the same, and to a light guide plate with improved luminance of a light incident portion and a light incident portion, and a liquid crystal display device having the same.

In recent years, as various portable electronic devices such as mobile phones, PDAs, and notebook computers are developed, the demand for a flat panel display device for light, thin and short that can be applied thereto is gradually increasing. As such flat panel display devices, LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), VFD (Vacuum Fluorescent Display), etc. have been actively researched, but mass production technology, ease of driving means, and high-definition implementation However, due to the realization of a large-area screen, liquid crystal display devices (LCDs) are currently in the spotlight.

The liquid crystal display device is a transmissive display device, and displays a desired image on the screen by adjusting the amount of light that passes through the liquid crystal layer by refractive index anisotropy of the liquid crystal molecules. Accordingly, in the liquid crystal display device, a back light unit, which is a light source that transmits through the liquid crystal layer, is installed for displaying an image. In general, the backlight unit can be largely divided into two types.

First, a lamp is installed on the side of the liquid crystal panel to provide light to the liquid crystal layer, and the second is a direct-type backlight in which the lamp provides light directly from the bottom of the liquid crystal panel.

The side type backlight is installed on the side of the liquid crystal panel to supply light to the liquid crystal layer through the reflector and the light guide plate. Accordingly, since it is possible to reduce the thickness, it is mainly used in notebook computers and the like that require a thin display device.

The direct type backlight is mainly used to manufacture a liquid crystal panel for an LCD TV in recent years because it can be applied to a large-area liquid crystal panel as well as high luminance since light emitted from a lamp is directly supplied to the liquid crystal layer.

1 is a diagram schematically illustrating a structure of a liquid crystal display device with an edge type backlight.

As shown in FIG. 1, the liquid crystal display device 1 is largely installed on a liquid crystal display panel 40 and a rear surface of the liquid crystal panel 40 to supply light to the liquid crystal panel 3. It consists of (10). The liquid crystal panel 3 is a place where an actual image is realized, and a liquid crystal layer formed between the first substrate 50 and the second substrate 45, which is transparent such as glass, and the first substrate 50 and the second substrate 45 It consists of (not shown in drawings). In particular, although not shown in the drawings, the first substrate 50 is a TFT substrate on which a driving element such as a thin film transistor and a pixel electrode are formed, and the second substrate 45 has a color filter layer. It is a color filter substrate to be formed. Further, a driving circuit part 5 is provided on the side surface of the first substrate 50 to apply signals to the thin film transistors and pixel electrodes formed on the first substrate 50, respectively.

The backlight 10 includes a lamp 11 emitting actual light, a light guide panel 13 guiding the light emitted from the lamp 11 toward the liquid crystal panel 40, and a light guide panel 13 that is emitted from the lamp 11. It is composed of a reflector 17 that reflects light to the light guide plate 13 to improve light efficiency, and an optical sheet composed of a diffusion sheet 15 and a prism sheet 20 disposed on the light guide plate 13.

In the backlight 10 as described above, light emitted from the lamps 11 installed on both sides of the light guide plate 13 is incident on the light guide plate 13 through the side surface of the light guide plate 13, and the incident light is transmitted to the light guide plate 13 After being supplied to the liquid crystal panel 40 through the upper surface of ), the light efficiency is improved by the optical sheet and then incident on the liquid crystal panel 40.

The light output from the light guide plate 13 is incident on the diffusion sheet 15 and the prism sheet 20 of the optical sheet, is diffused by the diffusion sheet, and then the propagation direction thereof is changed to the front by the prism sheet 20. Is output.

Polarizing plates 5a and 5b are disposed on the upper and lower surfaces of the liquid crystal panel 40, respectively. The light emitted from the backlight 10 is polarized in the first polarizing plate 5a attached to the first substrate 50, and the polarization state of the light is converted while passing through the liquid crystal layer. It is emitted to the outside through the two polarizing plate 5b. At this time, the transmittance of the light transmitted through the second polarizing plate 5b is adjusted according to the change in the polarization state of the light by the liquid crystal layer, thereby implementing an image.

The lamp 11 is formed on one or both side surfaces of the light guide plate 13 so that light is incident through the light incident surface of the light guide plate 13 facing the lamp 11. When the light incident on the light guide plate 13 is incident on the upper or lower surface of the light guide plate 13 at an angle less than the critical angle, the light is totally reflected and the light is propagated from one side of the light guide plate 13 to the other side, and the light is transmitted to the light guide plate 13. When incident on the upper or lower surface of the interior at an angle greater than the critical angle, it is output to the outside and reflected by the reflector 17 or supplied to the liquid crystal panel 40 through the upper surface.

As described above, since the side-type backlight disposed on the side of the lamp 11 and the light guide plate 13 is installed on the side of the liquid crystal panel, the thickness of the backlight can be made relatively thin, thereby realizing a thin display device. .

In this side-type backlight, in order to provide light of uniform brightness from the light guide plate 13 to the liquid crystal panel 40, the light emitted from the lamp 11 must be uniformly scattered. For the scattering of such light, the light guide plate 13 A pattern of a predetermined shape is formed on the lower surface. These patterns are formed in a positive or negative shape by various methods such as a screen printing method, a mold processing method, and a V-cutting method.

However, as described above, a method of scattering light supplied to the liquid crystal panel 40 by forming a pattern on the lower surface of the light guide plate 13 has the following problems. That is, the light incident through the light-incident surface of the light guide plate 13 is reflected from the upper and lower surfaces of the light guide plate 13 and is guided from the light-incident surface to the other side, and is emitted through the upper surface of the light guide plate 13 and is then transferred to the liquid crystal panel 40. Is supplied.

FIG. 2 is a diagram showing propagation of light inside the light guide plate 13 and light outputting the light guide plate 13.

As shown in FIG. 2, a pattern 14 is formed on the lower surface of the light guide plate 13. At this time, the pattern 14 is formed in a wedge shape having a set width, and the inclined surface is formed at a certain angle φ, so that light is incident inside the wedge-shaped inclined surface.

When light is incident from the light source 10 to the inside of the light guide plate 13 through the light incident surface, the light incident on the upper surface of the light guide plate 13 with an angle of incidence (θ1) higher than the critical angle (θc) is the upper surface. The light is output through the liquid crystal panel and is supplied to the liquid crystal panel, and the light incident below the critical angle θc is totally reflected from the upper surface of the light guide plate 13.

The light totally reflected from the upper surface of the light guide plate 13 is incident on the lower surface. At this time, a pattern 14 is formed on the lower surface of the light guide plate 13 so that the incident light is reflected from the inclined surface of the pattern 14 to the upper surface. Even at this time, light incident on the inclined surface of the pattern 14 at an angle equal to or less than the threshold value is output through the lower surface of the light guide plate 13 and then reflected by the reflecting plate 17 and is incident again to the light guide plate 13.

Since the inclined surface of the pattern 14 is formed at a certain angle (φ), when the light reflected from the inclined surface of the pattern 14 enters the upper surface of the light guide plate 13, the initial incident angle θ2 is the initial incident angle θ1 Since it increases compared to (θ1<θ2), the light in which the incident angle θ2 is greater than or equal to the critical angle among the total reflected light is output through the upper surface of the light guide plate 13.

As the light that has total reflection inside the light guide plate 13 by the above process is reflected from the inclined surface of the pattern 14, the angle of incidence incident on the upper surface gradually increases, so that all the light propagates through the inside of the light guide plate 13 The light guide plate 13 is supplied to the liquid crystal panel through the top surface.

As described above, in a conventional liquid crystal display device, in order for light incident to the light guide plate 13 to be output and supplied to the liquid crystal panel, it must be totally reflected several times inside the light guide plate 13, so that the light enters through the upper surface near the incident surface. Since the amount of light emitted is small, there is a problem that the luminance decreases compared to other areas.

Moreover, in large liquid crystal display devices applied to large electronic devices such as TVs, the light guide plate 13 is formed with PMMA (Polymethyl-Methacrylate) having a refractive index of 1.49, whereas small liquid crystal display devices used in mobile communication devices such as mobile phones Since the light guide plate 13 is mainly formed of a material having a high refractive index such as polyethylene terephthalate (PET) (refractive index 1.64), the size of the critical angle for total reflection is reduced by Snell's law, so the light incident surface in the light guide plate 13 As the output amount of light supplied to the liquid crystal panel in the vicinity decreases, in the case of a small liquid crystal display device, the problem of lowering the luminance near the light incident surface becomes more serious.

The present invention is to solve the above problems, by forming an upper surface of the light guide plate and an inclined surface that is inclined near the light incident surface of the light guide plate to change the reflection angle of light incident on the upper surface of the light guide plate. An object of the present invention is to provide a light guide plate and a liquid crystal display device capable of supplying a liquid crystal panel.

In order to achieve the above object, a light guide plate according to the present invention includes: a light guide plate main body for guiding input light and outputting it through an upper surface; And an inclined surface formed near a light-incident surface to which light is input and is formed to be inclined with an upper surface of the body to change a reflection angle of light reflected from the upper surface of the body.

A plurality of patterns are formed on a lower surface of the light guide plate body, and a lenticular pattern extending from a light incident surface to a light incident surface is formed on the upper surface of the light guide plate. In addition, a blocking means is formed on the light-incoming surface of the light guide plate at least partially and propagating through the lenticular pattern to block light output through the light-incoming surface.

In addition, a liquid crystal display device according to the present invention includes a liquid crystal panel on which an image is implemented; Light source; A light guide plate for guiding the light incident from the light source and supplying it to a liquid crystal panel; An inclined surface formed near a light incident surface to which light is input and is formed to be inclined with an upper surface of the main body to change a reflection angle of light reflected from the upper surface of the main body; And an external structure for assembling the liquid crystal panel, a light source, and a light guide plate.

1 is a cross-sectional view of a conventional liquid crystal display device.
2 is a cross-sectional view showing the structure of a light guide plate of a conventional liquid crystal display device.
3 is an exploded perspective view showing the structure of a liquid crystal display device according to the present invention.
4 is a cross-sectional view showing the structure of a liquid crystal display device according to the present invention.
5 is a view showing the structure of a liquid crystal panel according to the present invention.
6 is a cross-sectional view showing the structure of a light guide plate of a liquid crystal display device according to an embodiment of the present invention.
7 is a view showing a structure of a pattern formed on a lower surface of a light guide plate.
8 is a view showing a structure in which patterns are arranged on a lower surface of a light guide plate.
9A and 9B are views showing light guide in the light guide plate according to the prior art and the present invention, respectively.
10A and 10B are views showing the luminance in the light guide plate according to the prior art and the present invention, respectively.
11A and 11B are graphs showing bright lines in the conventional and the light guide plate according to the present invention, respectively.
12 is a cross-sectional view showing a structure of a light guide plate of a liquid crystal display device according to another embodiment of the present invention.
13A-13C are cross-sectional views showing the structure of the light guide plate shown in FIG. 12, respectively.

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

The easiest way to prevent the luminance from deteriorating in the light-incident portion (area near the light-incident surface) of the light guide plate is to increase the density of the pattern formed on the lower surface of the light-incident portion of the light-guide plate, or to form an additional pattern on the light-incident portion.

However, when the density is adjusted or an additional pattern is formed, manufacturing cost increases, and light is scattered by the additional pattern, resulting in a problem of lowering the luminance.

In the present invention, in order to prevent the luminance from deteriorating in the light-incident portion, it is possible to prevent a dark area from being formed in the light-incident portion by changing the shape of the light guide plate without forming a separate pattern.

3 is an exploded perspective view showing the structure of a liquid crystal display device according to the present invention, and FIG. 4 is a cross-sectional view of a liquid crystal display device according to the present invention.

As shown in FIGS. 3 and 4, the liquid crystal display device 100 includes a liquid crystal panel 140 and a backlight 110. In this case, the backlight 110 is positioned under the liquid crystal panel 140 to supply light to the liquid crystal panel 140.

The backlight 110 is a light source 111 that emits light and supplies it to the liquid crystal panel 140, and the light source 111 is disposed under the liquid crystal panel 140 so that a side surface contacts the light source 111 and through a side surface thereof. A light guide plate 113 that supplies light input from the liquid crystal panel 140 to the liquid crystal panel 140, and a reflector that is disposed under the light guide plate 113 and reflects light incident to the lower portion of the light guide plate 113 to the liquid crystal panel 140 117), a prism sheet disposed between the light guide plate 113 and the liquid crystal panel 140, and a plurality of prisms are arranged along one direction to totally reflect the light incident from the liquid crystal panel 140 to the front and supply it to the liquid crystal panel 140 It consists of an optical sheet containing 120.

In addition, a first polarizing plate 105a and a second polarizing plate 105b are attached to the upper and lower surfaces of the liquid crystal panel 140, respectively.

As shown in FIG. 5, the liquid crystal panel 140 includes a first substrate 150 and a second substrate 145, and a liquid crystal layer (not shown) therebetween. When a plurality of gate lines 156 and data lines 157 are arranged in a matrix shape on the first substrate 150 to define a plurality of pixel regions P, each pixel region P has a thin film transistor T ) And a pixel electrode 158 electrically connected to the thin film transistor T. A gate pad and a data pad are formed at ends of the gate line 156 and the data line 157 to connect the gate line 156 and the data line 157 to an external driving device. An external signal is input through the data line 125.

Although not shown in the drawing, the thin film transistor T is a gate electrode connected to a gate line 156 to receive a scanning signal from the outside through the gate line 156, and a gate insulating layer formed on the gate electrode. , A semiconductor layer formed on the gate insulating layer and activated when a scan signal is input to the gate electrode to form a channel, and the data line 157 is formed on the semiconductor layer to form a channel in the semiconductor layer by the scan signal. A source electrode and a drain electrode for applying an image signal input through the pixel electrode 158 to the pixel electrode 158.

The second substrate 145 is formed in an image non-display area where an actual image is not realized, such as a gate line 156, a data line 157, and a thin film transistor (T). Color consisting of a black matrix (146) that prevents transmission and deterioration of image quality, and sub-color filter layers of R (Red), G (Green), and B (Blue) that are formed in the pixel to realize an actual image A filter layer 147 is formed.

A liquid crystal layer (not shown) is formed between the first substrate 150 and the second substrate 145 configured as described above to form the liquid crystal panel 140, and the second substrate of the liquid crystal panel 140 A polarizing plate 105 is attached to 145.

As the light source 111, a fluorescent lamp such as a CCFL (Cold Cathod Fluorouscent Lamp) is mainly used. A reflective layer is formed on the inner surface of the housing 112 in which the light source 111 is accommodated to reflect the light emitted from the light source 111 to the light guide plate 113. In addition, the light source 111 may be formed only on one side of the light guide plate 113 as shown in FIG. 3, or is formed on both sides of the light guide plate 113 so that the light emitted from the light source 111 is transmitted from the light guide plate 113. It may be incident on the light guide plate 113 through both sides.

As the light source 111, not only a fluorescent lamp but also a light emitting device (LED) may be used. Such an LED is a light source that emits light by itself, and emits R, G, B monochromatic light, so that when applied to a backlight unit, it has an advantage of good color reproduction and saving driving power.

In the case of using such an LED as the light source 111 of the backlight unit, when the light emitted from the LED is supplied to the liquid crystal panel, the monochromatic light is not directly supplied but the white light is supplied, and the monochromatic light emitted from the light emitting device is made white light. For this, a monochromatic light emitting element and a phosphor are used, a light emitting element and a phosphor in an infrared wavelength band are used, or monochromatic light emitted from a light emitting element of red (R), green (G), and blue (B) colors is mixed. That is, when the LED is used as the light source 111 of the backlight unit, a plurality of LEDs are disposed on the side of the light guide plate 113 to input white light or monochromatic light to the light guide plate 113.

The prism sheet 120 forms a regular prism with an acrylic resin on a base film mainly made of polyethylene terephthalate (PET), refracts incident light, and causes the light traveling direction to be incident in the front direction. At this time, as shown in the drawing, since the prism of the prism sheet 120 is arranged in one direction, that is, in the x-direction, after propagating from the light incident surface of the light guide plate 113 to the other side, output at a certain angle through the upper surface The resulting light is totally reflected so that it is incident perpendicularly to the liquid crystal panel 140.

In addition, since the prism of the prism sheet 120 is formed on the lower surface of the prism of the prism sheet 120 and the vertices of the prism are disposed toward the light guide plate 113, light incident at a certain angle through the upper surface of the light guide plate 113 Is totally reflected to the front surface of the liquid crystal panel 140.

When the prism is formed on the upper surface of the prism sheet 120 and the vertex faces the liquid crystal panel 140, the light emitted from the light guide plate 113 is refracted rather than totally reflected by the prism of the prism sheet 120, and thus the liquid crystal panel 140 ), only the light incident on the prism at a specific angle is refracted and the angle incident at a different angle is not refracted, so that the light efficiency of the prism is lowered compared to the structure formed on the lower surface of the prism sheet 120.

In addition, in the structure in which the prism is formed on the lower surface of the prism sheet 120, since a separate optical sheet is not required, manufacturing cost can be reduced.

The light guide plate 113 propagates the light input from the side from one side to the other side and then emits it through the top surface to supply the light to the liquid crystal panel 140. In this case, as shown in FIG. 4, a pattern 114 is formed on the lower surface of the light guide plate 113, and light incident on the pattern 114 is reflected and output through the upper surface of the light guide plate 113.

6 is a cross-sectional view specifically showing the structure of the light guide plate 113 according to the present invention.

As shown in FIG. 6, the light guide plate 113 is formed of a material such as PMMA (Polymethyl-Methacrylate), glass, or polyethylene terephthalate (PET) in a rectangular shape.

A plurality of wedge-shaped patterns 114 are formed on the lower surface of the light guide plate 113. At this time, since the breathable inclined surface faces the light incident surface of the light guide plate 113, the inclined surface becomes a reflective surface of light totally reflected from the upper surface of the light guide plate 113. Since the path of light reflected from the inclined surface is determined according to the angle of the inclined surface of the pattern 114, the angle of the inclined surface of the pattern 114 is the material (eg, refractive index, etc.) of the light guide plate 113, area, and thickness. Depends on

In addition, in the light guide plate 113 of the present invention, the upper surface of the light guide plate 113 is formed to be inclined from the light incident surface to a predetermined area. That is, in the present invention, a certain area near the light incident surface of the light guide plate 113 is formed in a wedge shape, so that the upper surface of the light guide plate 113 is formed to be inclined from the light incident surface 113 to a certain distance l. In this case, the inclined region 113a is formed at an angle of ψ with respect to the upper surface of the light guide plate 113.

The distance 1 and the angle ψ of the inclined region 113a are determined by variables such as the material of the light guide plate 113, the area of the light guide plate 113, and the thickness of the light guide plate 113.

7 is a diagram illustrating a pattern 114 formed on a lower surface of the light guide plate 113. As shown in FIG. 7, the pattern 114 includes a bottom surface, side surfaces 114a and 114b formed in a vertical direction from three surfaces of the bottom surface, and an inclined surface 114c formed inclined from the side surface 114b to the bottom surface. At this time, the side (114b) of the end of the inclined surface (114c) is formed in a square or rhombus shape, and the side (114b) of the side of the inclined surface (114c) is formed in a triangular shape, so that the inclined surface is formed to be inclined from one end to the other end. do.

The inclined surface 114c is a surface through which light totally reflected inside the light guide plate 113 is incident and reflected. Accordingly, the incident angle of light incident on the upper surface of the light guide plate 113 is determined according to the angle of the inclined surface 114c with respect to the lower surface of the light guide plate 113.

In the drawings, a configuration in which the pattern 114 is formed only in a wedge shape is disclosed, but the shape of the pattern 114 is not limited to a specific shape. For example, the inclined surface 114c is formed in a fan shape rather than a square shape, so that the width of the lower surface of the light guide plate 113 is wider than the width of the top side of the inclined surface, and the central area of the inclined surface 114c is convex than the outer area. It is formed in the shape of a formed lens, so that the light guide plate 113 not only reflects the light reflected from the upper surface in the propagation direction of the light, but also spreads at a certain angle to both sides of the propagation direction, that is, the area between the adjacent patterns 114. By reflecting, light may be uniformly reflected over the entire light guide plate 113.

8 is a diagram illustrating a plurality of patterns 114 formed on the lower surface of the light guide plate 113. As shown in FIG. 8, the patterns 114 are arranged in a matrix shape under the light guide plate 113. That is, the pattern 114 is uniformly formed over the entire lower surface of the light guide plate 113. Of course, the pattern 114 may be formed at different densities for each area of the lower surface of the light guide plate 113.

FIG. 9 is a view showing actual light propagation in the light guide plate 113 having the above structure. FIG. 9A is a view showing propagation of light in the conventional light guide plate, and FIG. 9B is a view showing propagation of light in the light guide plate according to the present invention.

As shown in FIG. 9A, in the conventional light guide plate 13, when light emitted from the light source 11 is incident at an angle of incidence of α through the light incident surface and enters the upper surface 13 of the light guide plate at a threshold value or more, the light guide plate 13 ) Is totally reflected from the upper surface of the light guide plate 13 to the inclined surface of the pattern 14 formed on the lower surface of the light guide plate 13 at an angle of β.

Meanwhile, as shown in FIG. 9B, in the light guide plate 113 according to the present invention, light emitted from the light source 111 is incident through the light incident surface at an angle of incidence of α to the inclined region 113a of the upper surface 113 of the light guide plate. When the incident exceeds the threshold value, total reflection from the upper surface of the light guide plate 113 to the lower surface of the light guide plate 13 is incident on the inclined surface formed on the lower surface of the light guide plate 113.

At this time, in the conventional light guide plate 13, since the incident light is reflected from the flat upper surface, it is incident on the pattern 14 at an angle of β, but in the light guide plate 113 of the present invention, the incident light is reflected on the inclined surface and is incident on the lower surface. , The angle of incidence to the pattern becomes β+2Ψ. Here, Ψ is an angle of inclination of the inclined region with respect to the upper surface of the light guide plate 113, and in the present invention, the angle of incidence to the lower surface is different according to the inclination angle Ψ of the inclined region 113a of the light incident part.

Therefore, the incident angle θ2 at which the light reflected from the light guide plate of the present invention is incident on the upper surface of the light guide plate is greater than the incident angle θ1 at which the light reflected from the conventional light guide plate is incident on the upper surface of the light guide plate (θ2>θ1).

Among the light incident on the upper surface of the light guide plate 113, light with an incidence angle greater than or equal to the critical angle θc is output through the upper surface and supplied to the liquid crystal panel, and the light incident less than the critical angle θc is the upper surface of the light guide plate 113 Because of the total reflection in the light guide plate 113 of the present invention, compared to the conventional light guide plate 13, more light is output from the light guide plate 113 at the light incident portion.

In other words, even when light is incident to the light guide plate through the light incident surface at the same angle of incidence, even if it is not output through the upper surface of the light guide plate 13 in the related art, in the present invention, the liquid crystal panel is output through the upper surface of the light guide plate 113 Is supplied with light. In particular, in the case where light is not output from the conventional light guide plate 13 at the light-incident portion near the light-incident surface, in the present invention, an inclined surface is formed so that light is also output from the light-incident portion.

Tables 1 and 2 show the reflection angle on the upper surface of the light guide plate, the reflection angle on the inclined surface, the reflection angle in the pattern, and the total number of times when the light propagates within the light guide plate after light is received in the conventional light guide plate and the light guide plate according to the present invention, respectively. Show.

angle of incidence Light guide angle after top reflection Light guide angle after pattern reflection Reflection One 89.4 85.4 12 10 83.7 79.7 10 20 77.6 73.6 9 30 71.7 67.7 7 40 66.2 62.2 6 50 61.2 57.2 5 60 57 53 4 70 53.8 49.8 3 80 51.7 47.7 2 90 51 47 2

angle of incidence Light guide angle after slope reflection Light guide angle after pattern reflection Reflection One 75.4 71.4 8 10 69.7 65.7 7 20 63.6 59.6 5 30 57.7 53.7 4 40 52.2 48.2 2 50 47.2 43.2 One 60 43 39 0 70 39.8 35.8 0 80 37.7 33.7 0 90 37 33 0

As shown in Tables 1 and 2, when light is incident at the same angle of incidence through the light incident surface of the conventional light guide plate and the light guide plate according to the present invention, in the conventional light guide plate, the incident light is reflected from the top surface of the flat light guide plate, It is reflected again by, but in the present invention, it is reflected again by the pattern after being reflected from the inclined surface of the upper surface of the light guide plate.

Therefore, the light guide angle after reflection on the upper surface of the light guide plate according to the present invention is different from that of the conventional light guide plate, and the light guide angle is reduced in the case of the light guide plate according to the present invention compared to the conventional light guide plate. In addition, the light guide angle of the light reflected from the pattern is also reduced compared to the conventional light guide plate.

The decrease in the light guide angle after pattern reflection means a decrease in the angle of incidence with respect to the normal of the upper surface incident on the upper surface of the light guide plate after the pattern reflection. After being reflected from the pattern, the light incident on the upper surface of the light guide plate is reflected again from the upper surface of the light guide plate and then reflected from the pattern on the lower surface. At this time, since the light is reflected by the inclined surface of the pattern on the lower surface, the light guide angle of the light after the pattern reflection decreases as the reflection proceeds, so the incidence angle with respect to the normal of the upper surface incident on the upper surface of the light guide plate also decreases as the reflection proceeds. do.

In this way, as the reflection proceeds, the incident angle incident on the upper surface of the light guide plate decreases, and when the incident angle becomes less than or equal to the critical angle θc, light is not reflected from the upper surface of the light guide plate, but is output to the outside of the light guide plate and supplied to the liquid crystal panel. .

As shown in Tables 1 and 2, when light is incident on the light guide plate at the same incidence angle, the number of total reflections in the light guide plate of the present invention decreases compared to the conventional light guide plate. When the angle of incidence increases to more than 60 degrees, the conventional light guide plate reflects light 2-4 times, but no further reflection occurs in the present invention.

In other words, in the conventional light guide plate, when light is incident through the light-incident surface at an angle of 1-90, it is reflected at least twice inside the light-guide plate, so it is reflected at least twice on the light-incident surface and then output from the light guide plate. The light does not emit from the light-incident portion, so that the luminance of the light-incident portion decreases. Of course, after the light is totally reflected from the light incident part to the carry-in part (opposite side of the light incidence part), it is totally reflected in the opposite direction to output the light through the light-incident part, but the amount of light output compared to other areas Because this is small, the luminance at the light-incident portion decreases.

On the other hand, in the present invention, when light is incident at an incidence angle of 60 degrees or more through the light-incident surface, it is emitted as it is without reflection inside the light guide plate and supplied to the liquid crystal panel. Accordingly, since light is not reflected from the light-incident portion near the light-incident surface and light is emitted, the luminance of the light-incident portion and other areas is the same.

10A and 10B are views showing luminance of a conventional light guide plate and a light guide plate according to the present invention, respectively. At this time, in FIGS. 10A and 10B, the lower side is the light incident surface.

As shown in FIG. 10A, in the conventional light guide plate 13, since the amount of light output through the upper surface of the light guide plate 13 from the light incident portion near the light incident surface is small, the luminance decreases toward the light incident surface, thereby increasing the darkness.

On the other hand, as shown in FIG. 10B, in the light guide plate 13 according to the present invention, since the light-incident portion near the light-incident surface and the overall uniform luminance are exhibited in a different area, the dark portion does not occur near the light-incident surface.

11A and 11B are graphs showing bright lines of a conventional light guide plate and a light guide plate according to the present invention, respectively. At this time, the right side of the coordinates is the light incident surface of the light guide plate, and the left side is the incoming light surface.

As shown in FIGS. 11A and 11B, in the conventional light guide plate, the luminance decreases from the light-incident surface to the light-incident surface, whereas in the light guide plate according to the present invention, the luminance is almost the same from the light-incident surface to the light-incident surface. Accordingly, in the conventional light guide plate, the luminance of the light-incident portion near the light-incident surface is lowered, whereas in the light guide plate of the present invention, such a problem can be effectively prevented.

As described above, in the present invention, by forming the upper surface of the light guide plate 113 near the light-incident surface to be inclined to supply light of uniform brightness to the liquid crystal panel, it is possible to effectively prevent the phenomenon that the brightness of the light-incident portion decreases do.

12 is a view showing the structure of a light guide plate according to another embodiment of the present invention.

As shown in Fig. 12, in this embodiment, a lenticular lens-shaped pattern 215 is formed on the upper surface of the light guide plate 213 by extending from the light incident surface toward the incoming light. In this way, when the lenticular pattern 215 in the shape of a lenticular lens is formed on the light guide plate 213, the light emitted to the upper surface of the light guide plate 213 is refracted by the lenticular pattern 215 and goes straight upward, The luminance of light supplied to the liquid crystal panel increases. Also, in the light guide plate 213 of this embodiment, the upper surface of the area near the light-incident surface to which the light emitted from the light source 211 is incident has an inclined structure.

However, in the case of the light guide plate 213 having the above structure, since the lenticular pattern 215 extends from the light incident surface toward the incoming light, light emitted from the light source 211 and incident into the light guide plate 213 through the light incident surface Since the light is guided by going straight along the lenticular shape, the light passes out of the light guide plate 213 through the carrying-in light part. In particular, in the case of the light guide plate 213 having a high refractive index such as PET, since this phenomenon becomes more severe, a bright line that appears abnormally high in luminance near the light guide portion of the light guide plate 213 is generated.

In the present invention, in the case of forming the lenticular pattern 215 on the upper surface of the light guide plate 213 as described above, in order to prevent the generation of bright lines in the light guide plate 213, a blocking block that blocks light from exiting the light guide surface of the light guide plate 213 It has means 218, which will be described in more detail.

13A-13C are cross-sectional views taken along line II′ of FIG. 12, respectively.

First, as shown in FIG. 13A, a blocking means 218 such as a black film or black resin is formed over the entire surface of the light guide plate 213. Substantially, the area from which the light is emitted from the light guide plate 213 is the area where the lenticular pattern 215 extends. Therefore, the blocking means 218 can be provided only at a position corresponding to the region where the lenticular pattern 215 extends, but in the case of a small liquid crystal display device, since this region is very small, the blocking means 218 is applied to a plurality of small regions. Since it is not easy to attach or apply, the blocking means 218 is attached or applied over the entire light incident surface. Of course, it is possible to partially attach or apply the blocking means 218.

In this way, by providing the blocking means 218 on the light guide plate 213, the light that travels straight along the lenticular shape and reaches the light entering surface is blocked and absorbed by the blocking means 218, so that the light is transmitted through the light guide plate 213. It is possible to effectively prevent the generation of bright lines in this area by being emitted.

Meanwhile, as shown in FIG. 13B, the external structure 280 of the liquid crystal display device in contact with the light-incident surface of the light guide plate 213 may be blackened to absorb light output through the light-incident surface.

Although not shown in the drawings, a liquid crystal display device includes a lower cover, an upper cover, and a guide panel for supporting and assembling a liquid crystal panel and a backlight. The assembly structure of the lower cover, the upper cover and the guide panel may be variously installed according to the size of the liquid crystal display device. In this structure, instead of providing a blocking means on the light-incoming surface of the light guide plate 213, among external structures such as the lower cover, the upper cover, and the guide panel, only the area where the light-guide plate 213 faces the light-incoming surface is blackened to make the carrying-in light surface. By absorbing the light output to the outside through the light guide plate 213 at a lower price than the structure of FIG. 13A, it is possible to prevent a bright line from being generated in the light-incoming portion of the light guide plate 213.

In addition, as shown in FIG. 13C, in the present invention, the external structure 280 of a liquid crystal display device such as a lower cover, an upper cover, and a guide panel is in contact with the light guide plate 213, and the light guide plate in contact with the light guide plate 213. By attaching or applying the blocking means 218 of a certain width to the lower surface of the 213, it is possible to absorb or block the light output to the outside through the incoming light surface. In this case, the external structure 280 may be blackened.

As described above, in the present invention, the luminance of light supplied to the liquid crystal panel is improved by increasing the luminance of the light output to the light-incident portion near the light-incident surface by changing the reflection angle of the light reflected from the upper surface by forming the upper surface of the light guide plate in an inclined manner. Can be made uniform throughout. Accordingly, it is possible to prevent a deterioration in image quality due to a decrease in luminance of the light incident unit.

Meanwhile, in the above description, a backlight including a light guide plate and a liquid crystal device are described with a specific structure, but the present invention is not limited to a backlight or a liquid crystal display device having such a specific structure.

Accordingly, various modifications of the present invention and structures that can be easily created based on the present invention should also be included in the scope of the present invention. Therefore, the scope of the present invention should be determined not by the above detailed description, but by the appended claims.

100: liquid crystal display device 110: backlight
111: light source 113: light guide plate
113a: inclined surface 117: reflector
140: liquid crystal panel

Claims (10)

A main body that guides the input light and outputs it through an upper surface;
An inclined surface formed near a light-incident surface to which light is input and is formed to be inclined with an upper surface of the main body to change a reflection angle of light reflected from the upper surface of the main body;
A plurality of patterns formed on the lower surface of the body; And
It consists of a lenticular pattern formed on the upper surface of the body and extending from the light-incident surface to the light-incident surface,
Each pattern includes an inclined surface that reflects incident light, and the inclined surface has a wider width from the top side to the bottom side of the main body, and the central area along the vertical direction of the light propagation direction is formed in a convex lens shape than the outer area Light guide plate, characterized in that the. delete delete The light guide plate according to claim 1, further comprising a blocking means formed at least in part on the light-in-carrying surface of the main body, propagating through the lenticular pattern, and blocking light output through the light-incoming surface. The light guide plate as claimed in claim 1, further comprising a blocking means arranged to have a width set on a lower surface of the main body under the light-incoming surface, propagating through the lenticular pattern, and blocking light output through the light-incoming surface. A liquid crystal panel on which an image is implemented;
Light source;
A light guide plate for guiding the light incident from the light source and supplying it to a liquid crystal panel;
A plurality of patterns formed near at least a light incident surface of the light guide plate to which light is input, and including an inclined surface formed to be inclined with an upper surface of the light guide plate to change a reflection angle of light reflected from the upper surface of the light guide plate; And
It is composed of an external structure for assembling the liquid crystal panel, the light source, and the light guide plate,
The inclined surface of the pattern is wider from the top side to the bottom side of the light guide plate, and the central area is formed in a convex lens shape than the outer area along the vertical direction of the light propagation direction,
A liquid crystal display device, characterized in that the area of the external structure facing the light-incident surface of the light guide plate is blackened to absorb light directly inputted to the external structure through the light-incoming surface. The method of claim 6,
A lenticular pattern formed on an upper surface of the light guide plate and extending from a light incident surface to a light incident surface; And
A liquid crystal display device, further comprising a blocking means for blocking light propagating through the lenticular pattern of the light guide plate and outputting through the carrying surface. The liquid crystal display device according to claim 7, wherein the blocking means is disposed at least in part on the light-incident surface of the light guide plate. delete The liquid crystal display according to claim 7, further comprising a blocking means disposed on a lower surface of the light guide plate at a set width below the light guide plate to block light that is propagated through the lenticular pattern and output through the light guide surface. device.

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