KR102189868B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display device, and to a liquid crystal display device including a backlight unit having improved light efficiency and a method of manufacturing a light guide plate.
A feature of the present invention is that a dot pattern is formed on the upper surface of the light guide plate, and by placing an inverted prism-acid light collecting sheet on the upper surface of the light guide plate, it is possible to maintain the polarization characteristics of the specific linearly polarized light incident into the light guide plate through the reflective polarizing film. have.
In addition, it is possible to improve the forward light emission rate of the light guide plate, and thus, a surface light source of higher luminance can be provided as a liquid crystal panel.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device, and to a liquid crystal display device including a backlight unit having improved light efficiency.

In line with the recent information age, the display field has also developed rapidly, and in response to this, it is a flat panel display device (FPD) with advantages of thinner, lighter, and low power consumption, and is a liquid crystal display device. : LCD), plasma display panel device (PDP), electroluminescence display device (ELD), field emission display device (FED), etc. were introduced, and the existing cathode ray tube (cathode ray) tube: CRT) is rapidly replacing and attracting attention.

Among these, liquid crystal displays are excellent in displaying moving images and are most actively used in notebooks, monitors, and TV fields due to their high contrast ratio. However, liquid crystal displays are elements that do not have their own light-emitting elements and are a separate light source. Will ask for.

Accordingly, a backlight unit including a light source is provided on the rear surface of the liquid crystal panel to irradiate light toward the front surface of the liquid crystal panel, thereby realizing an image with a luminance that can be identified.

On the other hand, a general backlight unit is divided into a side light method and a direct type method according to the arrangement structure of the light source, and the side light method is a structure in which one or a pair of light sources are disposed on one side of the light guide plate. Or, two or two pairs of light sources are disposed on each side of the light guide plate, and the direct type method has a structure in which several light sources are disposed under the optical sheet.

Here, the side light method is easier to manufacture than the direct type method, and has the advantage of being thinner than the direct type, light in weight and low power consumption.

1 is a cross-sectional view of a liquid crystal display device using a general side light type backlight unit.

As shown, a general liquid crystal display device includes a liquid crystal panel 10, a backlight unit 20, a guide panel 30, a cover bottom 50, and a top cover 40.

The liquid crystal panel 10 is a part that plays a key role in image expression and is composed of first and second substrates 12 and 14 bonded to each other with a liquid crystal layer therebetween. A printed circuit board (not shown) is connected to each other through a connecting member (not shown) along two adjacent edges of the liquid crystal panel 10.

At this time, polarizing plates 19a and 19b that selectively transmit only specific light are attached to the outer surfaces of each of the first and second substrates 12 and 14 of the liquid crystal panel 10.

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

The backlight unit 20 includes an LED assembly 29 arranged along the longitudinal direction of at least one edge of the guide panel 30, a white or silver reflector 25 mounted on the cover buttum 50, and such a reflector ( 25) and a light guide plate 23 mounted on the light guide plate 23 and an optical sheet 21 interposed thereon.

Here, the LED assembly 29 includes a plurality of LEDs 29a and a PCB 29b on which a plurality of LEDs 29a are mounted.

The liquid crystal panel 10 and the backlight unit 20 have a top cover 40 surrounding the upper surface of the liquid crystal panel 10 and the back of the backlight unit 20 while the edges are surrounded by a rectangular guide panel 30 The cover buttum 50 covering the is coupled at the front and rear sides, and is integrated through the guide panel 30 as a medium.

Accordingly, the light emitted from the LED assembly 29 enters the light guide plate 23 and then refracts in the direction of the liquid crystal panel 10, and is processed into a high quality of uniform luminance while passing through the optical sheet 21, so that the liquid crystal panel 10 Is incident on, thereby causing the liquid crystal panel 10 to display an image to the outside.

On the other hand, in such a liquid crystal display, some of the light emitted from the backlight unit 20 is absorbed and reflected by the first polarizing plate 19a and is lost, which corresponds to 50% of the light emitted from the backlight unit 20 .

In addition, in the process of passing through the liquid crystal layers (not shown) including the first and second substrates 12 and 14, they are absorbed and reflected, and some of them are lost again, thereby exhibiting a very weak disadvantage in terms of luminance.

The present invention is to solve the above problems, the first object is to minimize the light loss to improve the light efficiency of the liquid crystal display, and thereby, to provide a high-brightness liquid crystal display is a second object. To do.

In addition, the third object is to maintain the polarization characteristics incident into the light guide plate.

In particular, the fourth purpose is to allow light of high luminance to be emitted from the light guide plate.

In order to achieve the object as described above, the present invention includes a reflector; A light guide plate mounted on the reflective plate and having a dot pattern formed on an upper surface thereof; An LED assembly arranged along the light incident surface of the light guide plate; An optical sheet mounted on the light guide plate and including an inverted prism acid light collecting sheet; It provides a liquid crystal display device including a liquid crystal panel mounted on the optical sheet.

In this case, a reflective polarizing film is positioned between the light incident surface and the LED assembly, and the reflective polarizing film is made of a multilayer thin film structure in which a polarizer is embedded in a laminate structure of dielectric thin films having different refractive indices, or is arranged side by side in one direction. It is one selected among wire grid reflective polarizing films including fine metal patterns.

In addition, the dot pattern has a rectangular shape, a plurality of them are distributed and arranged spaced apart, has a diameter of 10 ~ 500㎛, the height is 1/2±10% of the diameter, and the dot pattern is from the light incident surface to the carrying light surface. Increasingly, it is formed at a higher density per unit area.

In addition, the inverted prism mountain light collecting sheet has a plurality of prismatic mountains protruding toward the upper surface of the light guide plate, and the plurality of prismatic mountains are formed in a strip shape in which mountains and valleys are repeated along the length direction of the LED assembly.

As described above, by forming a dot pattern on the upper surface of the light guide plate according to the present invention, and by placing an inverted prism-acid light collecting sheet on the upper part of the light guide plate, the polarization characteristics of the specific linearly polarized light incident into the light guide plate through the reflective polarizing film There is an effect that can be made to maintain.

In addition, it is possible to improve the forward light emission rate of the light guide plate, and thus there is an effect of providing a surface light source of higher brightness to the liquid crystal panel.

1 is a cross-sectional view of a liquid crystal display device using a general side light type backlight unit.
2 is an exploded perspective view of a liquid crystal display device according to the present invention.
3 is an exploded perspective view schematically illustrating the backlight unit of FIG. 2.
4A to 4B are schematic diagrams schematically showing FIG. 3.
5 is a simulation result of measuring the polarization transmittance of the light guide plate and the light emission rate of the upper surface according to the aspect ratio of the dot pattern.
Figure 6 is a schematic cross-sectional view of a partial cross-section of Figure 2 modularized.

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

2 is an exploded perspective view of a liquid crystal display device according to the present invention.

As shown, the liquid crystal display device includes a liquid crystal panel 110, a backlight unit 120, a guide panel 130, a cover bottom 150, and a top cover 140.

First, the liquid crystal panel 110 is a part that plays a key role in image expression, and includes first and second substrates 112 and 114 bonded to each other with a liquid crystal layer therebetween.

At this time, under the premise of the active matrix method, although not clearly shown in the drawings, a plurality of gate lines and data lines cross the inner surface of the first substrate 112, which is usually called a lower substrate or an array substrate, so that a pixel is defined. In addition, a thin film transistor (TFT) is provided at each intersection point and is connected to a transparent pixel electrode formed in each pixel in a one-to-one correspondence.

And the inner surface of the second substrate 114 called the upper substrate or the color filter substrate, as an example, corresponding to each pixel, color filters of red (R), green (G), and blue (B) colors, and these A black matrix is provided surrounding each of the gate lines, data lines, and non-display elements such as thin film transistors. In addition, a transparent common electrode covering them is provided.

The gate and the data printed circuit board 117 are connected via a connecting member 116, such as a flexible circuit board, along at least one edge of the liquid crystal panel 110, so that the side surface of the guide panel 130 or the cover bottom during the modularization process. It is in close contact with the back of 150.

In addition, although not clearly shown in the drawing, an alignment layer that determines the initial molecular arrangement direction of the liquid crystal is interposed at the boundary between the two substrates 112 and 114 of the liquid crystal panel 110 and the liquid crystal layer filled therebetween. A seal pattern is formed along the edges of both substrates 112 and 114 to prevent leakage.

At this time, first and second polarizing plates 119a and 119b (see FIG. 6) are attached to outer surfaces of the first and second substrates 112 and 114, respectively.

A backlight unit 120 that supplies light is provided on the rear surface of the liquid crystal panel 110 so that the difference in transmittance indicated by the liquid crystal panel 110 is expressed to the outside.

The backlight unit 120 includes an LED assembly 129 and a reflective polarizing film 210 arranged along at least one edge length direction of the guide panel 130, a white or silver reflector 125, and the reflective plate 125 It includes a light guide plate 220 mounted on and an optical sheet 121 interposed thereon.

The aforementioned LED assembly 129 is a light source of the backlight unit 120 and is located on one side of the light guide plate 220 so as to face the light incident surface 221a (refer to FIG. 3) of the light guide plate 220, and such an LED assembly 129 Includes a plurality of LEDs 129a and a PCB 129b in which a plurality of LEDs 129a are mounted at regular intervals.

A bar-shaped reflective polarizing film 210 is located in front of the LED 129a of the LED assembly 129, and the reflective polarizing film 210 only captures specific linearly polarized light from the light emitted from the LED 129a. The light efficiency of the liquid crystal display device of the present invention is further improved by passing through and reflecting and regenerating the remaining light.

In addition, the light guide plate 220 to which the specific linearly polarized light transmitted through the reflective polarizing film 210 is incident is spread evenly to a wide area of the light guide plate 220 by multiple times of total reflection, and the liquid crystal panel 110. To provide a surface light source.

In particular, the light guide plate 220 according to the embodiment of the present invention has a hemispherical dot pattern 223 formed on the upper surface 221e (refer to FIG. 3). Through this, the liquid crystal display device of the present invention comprises a reflective polarizing film 210 ), the polarization characteristics of the specific linearly polarized light incident into the light guide plate 220 may be kept constant, and a large amount of light may be emitted to the front of the light guide plate 220.

The reflector 125 is located on the rear surface of the light guide plate 220 and reflects the light passing through the lower surface 220d of the light guide plate 220 (see FIG. 3) toward the liquid crystal panel 110 to improve the luminance of the light.

The optical sheet 121 on the upper part of the light guide plate 220 includes a diffusion sheet and at least one light collecting sheet 230, and diffuses or condenses the light that has passed through the light guide plate 220 to form a more uniform surface to the liquid crystal panel 110. Let the light source enter.

At this time, the light collecting sheet 230 is made of an inverted prism light collecting sheet in which a plurality of prism mountains 231 (see FIG. 3) protrude toward the light guide plate 220.

Through this, a surface light source of high brightness can be provided to the liquid crystal panel 110. We will look at this in more detail later.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the guide panel 130, and the cover bottom 150, and the top cover 140 includes the upper edge of the liquid crystal panel 110 and the Organize to cover the side.

Here, the top cover 140 has a rectangular frame shape in which the cross section is bent in a “b” shape so as to cover the upper and side edges of the liquid crystal panel 110, and the front cover of the top cover 140 is opened to cover the liquid crystal panel 110. It is configured to display an image implemented in.

In addition, the liquid crystal panel 110 and the backlight unit 120 are seated to form the basis for assembling the entire liquid crystal display device, and the cover buttom 150 includes a horizontal surface 151 and a vertically bent edge portion 153 thereof. .

In addition, the guide panel 130 in the shape of a square frame that is seated on the cover bottom 150 and surrounds the edges of the liquid crystal panel 110 and the backlight unit 120 is provided with the top cover 140 and the cover bottom 150 Are combined.

At this time, the top cover 140 may be referred to as a case top or a top case, the guide panel 130 may be referred to as a support main or main support, or a mold frame, and the cover bottom 150 is referred to as a bottom cover or a lower cover. It also loses.

At this time, in the liquid crystal display device having the above-described structure, the top cover 140 and the cover bottom 150 may be deleted in order to implement a light weight and thin liquid crystal display device that is recently required. By removing the top cover 140 and the cover bottom 150, the liquid crystal display can be lightweight and thin, and has an effect of simplifying the process.

In addition, due to the deletion of the top cover 140 and the cover bottom 150 made of a metal material, the process cost may be reduced.

As described above, in the liquid crystal display device of the present invention, a hemispherical dot pattern 223 is formed on the upper surface 220e (refer to FIG. 3) of the light guide plate 220, and the optical sheet 121 faces the light guide plate 220. By including the inverted prism light collecting sheet 230 in which a plurality of prismatic mountains 231 (see FIG. 3) are protrudingly arranged, the polarization characteristics of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 are maintained. At the same time, a large amount of light can be emitted to the front of the light guide plate 220.

Through this, a surface light source of high brightness can be provided to the liquid crystal panel 110.

3 is an exploded perspective view schematically illustrating the backlight unit of FIG. 2, and FIGS. 4A to 4B are schematic diagrams schematically showing FIG. 3.

As shown in FIG. 3, the backlight unit 120 includes an LED assembly 129 and an LED assembly 129 formed of an LED 129a as a light source and a PCB 129b on which the LED 129a is mounted, and a light incident surface 221a. ), a light guide plate 220 positioned to face the light guide plate 220, a reflective plate 125 positioned below the light guide plate 220, and an optical sheet 121 positioned above the light guide plate 220.

In addition, a bar-shaped reflective polarizing film 210 is positioned between the LED assembly 129 and the light incident surface 221a of the light guide plate 220.

At this time, the plurality of LEDs 129a emit white light in front toward the light-incident surface 221a of the light guide plate 220, including an LED chip (not shown) that emits all RGB colors or emits white color. In addition, a plurality of LEDs 129a emit light having colors of red (R), green (G), and blue (B), respectively, and by turning on these multiple RGB LEDs 129a at once, white light due to color mixing is suppressed. It can also be implemented.

In addition, the reflective polarizing film 210 is formed to have the same polarization axis as the polarization axis of the first polarizing plate 119a positioned under the liquid crystal panel (110 in FIG. 2) as shown in FIGS. 4A and 4B, through which, In the process of passing through the reflective polarizing film 210 and entering the light guide plate 220, the light is emitted to the outside of the light guide plate 220 and is provided to the liquid crystal panel (110 in FIG. 2). It is transmitted through 119a) and provided as a liquid crystal panel (110 in FIG. 2).

That is, the light emitted from the backlight unit 120 is transmitted through the first polarizing plate 119a by the first polarizing plate 119a and only light having the same polarization axis as the polarization axis of the first polarizing plate 119a is absorbed. And light loss is caused by being reflected. In the liquid crystal display of the present invention, by placing the reflective polarizing film 210 having the same polarization axis as the first polarizing plate 119a in front of the LED 129a of the LED assembly 129 , Only light having the same polarization axis as the polarization axis of the first polarizing plate 119a is emitted from the backlight unit 120.

Through this, the transmittance of the first polarizing plate 119a is improved, thereby increasing the amount of light supplied to the liquid crystal panel (110 in FIG. 2), thereby realizing high luminance.

In addition, the light guide plate 220 is selected from a plastic material such as polymethylmethacrylate (PMMA), which is an acrylic transparent resin that is one of the transmissive materials capable of transmitting light, or a polycarbonate (PC) series. It can be manufactured as one, but PMMA, which induces the diffusion of light when light passes through it because of its excellent transparency, weather resistance, and colorability, is the most widely used.

The light guide plate 220 connects the light incident surface 221a corresponding to the LED assembly 129a, the light incident surface 221b corresponding thereto, and the light incident surface 221a and the light incident surface 221b. It consists of a surface 221e, a lower surface 221f facing the reflector 125, and both side surfaces 211c and 211d facing each other.

The light guide plate 220 may include a pattern of a specific shape on the lower surface to supply a uniform surface light source. Here, the pattern may be configured in various ways such as an elliptical pattern, a polygon pattern, and a hologram pattern in order to guide the light incident into the light guide plate 220. The pattern is formed on the lower surface of the light guide plate 220 by a printing method or an injection method.

In addition, a hemispherical dot pattern 223 is protruded on an upper surface 221e of the light guide plate 220.

A plurality of dot patterns 223 are formed on the upper surface 221e of the light guide plate 220 in a positive shape and are distributed and arranged at regular intervals, wherein the dot patterns 223 are formed to have a diameter of 10 to 500 μm, and the dot pattern It is preferable that the height of 223 is formed to have a height corresponding to 1/2±10% of the diameter.

That is, the dot pattern 223 may be formed to have a diameter of 100 μm, and at this time, the dot pattern 223 is formed to have a height of 50 μm.

5 is a simulation result of measuring the polarization transmittance of the light guide plate and the light emission rate of the upper surface according to the aspect ratio of the dot pattern.

Here, the Aspect Ratio is a ratio of the height to the radius of the dot pattern, and referring to FIG. 5, it can be seen that the polarization transmittance is improved as the Aspect Ratio is closer to 1.

At this time, the dot pattern 223 is formed with a higher density per unit area from the light incident surface 221a on which the reflective polarizing film 210 is attached to the light incident surface 221b where the LED assembly 129 is located.

That is, the density of the dot pattern 223 is formed to be denser as the LED assembly 129 is located from the light incident surface 221a of the light guide plate 220 toward the light-incident surface 221b of the light guide plate 220.

This is, when the LED assembly 129, which is a light source, is located only on the side of the light incident surface 221a of the light guide plate 220, the liquid crystal panel (110 in FIG. 2) from the side of the light incident surface 221a of the light guide plate 220 to which light is incident. The amount of light emitted toward the light guide plate 220 is larger than the amount of light emitted toward the liquid crystal panel (110 in FIG. 2) from the side of the light guide plate 220, and is a uniform surface light source to the liquid crystal panel (110 in FIG. 2). It becomes difficult to provide.

In this case, the denser the dot pattern 223 formed on the upper surface 221e of the light guide plate 220, the more light incident into the light guide plate 220 may be directed toward the liquid crystal panel (110 in FIG. 2).

Therefore, the dot pattern 223 formed on the upper surface 221e of the light guide plate 220 is formed at a higher density per unit area from the light incident surface 221a toward the carrying light surface 221b, so that the light incident surface of the light guide plate 220 ( The amount of light emitted from the side 221a) toward the liquid crystal panel (110 in FIG. 2) and the amount of light emitted from the side of the light guide plate 220 toward the liquid crystal panel (110 in FIG. 2) may be the same. There is.

Through this, light having a uniform luminance can be emitted from the light guide plate 220, so that a uniform surface light source can be incident on the liquid crystal panel (110 in FIG. 2).

In addition, the optical sheet 121 positioned above the light guide plate 220 is composed of a diffusion sheet and at least one light collecting sheet 230, in which case, the light collecting sheet 230 is a plurality of prismatic mountains toward the light guide plate 220. It consists of an inverted prism light collecting sheet in which 231 is protrudingly arranged.

That is, the rear surface of the light collecting sheet 230 is arranged adjacently along the longitudinal direction of the light collecting sheet 230 corresponding to one edge where the LED assembly 129 is located, so that the band-shaped cross-section repeats mountains and valleys. A plurality of prism mountains 231 are arranged protruding from the rear surface.

Accordingly, the liquid crystal display device of the present invention has the effect of maintaining the polarization characteristics of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 and further improving the light emission efficiency of the light guide plate 220. Can be implemented.

Looking at this in more detail, the light emitted from the LED 129a of the LED assembly 129 is transferred to the inside of the light guide plate 220 by the reflective polarizing film 210 located in front of the LED assembly 129. In this case, a large amount of light is reflected by the inside of the light guide plate 220 and the reflecting plate 125, and the polarization characteristics of the specific linearly polarized light are changed.

However, in the present invention, the dot pattern 223 is formed on the upper surface 221e of the light guide plate 220, and the light collecting sheet 230 of the optical sheets 121 positioned above the light guide plate 220 is attached to the light guide plate 220. By making it consist of an inverted-prism-mounted condensing sheet in which the prismatic mountains 231 protrude toward the light guide plate 220, the polarization characteristics of the specific linearly polarized light can be maintained without changing, and the upper surface of the light guide plate 220 is exposed. Can improve light flux.

Table (1) below is a result of comparing the degree of polarization of the conventional backlight unit and the backlight unit 120 according to an embodiment of the present invention.

division Polarization degree Conventional backlight unit 20 to 36% Backlight unit according to an embodiment of the present invention 90%↑

Here, the degree of polarization (DOP) is the result of measuring the ratio of the transmittance of the polarizing plate that can express the retention of the polarization characteristics of the light emitted from the light guide, and DOP = (TE-TM)/(TE+TM)*100 [%] (Here, TE stands for transverse electric wave and TM stands for transverse magnetic wave.)

Referring to Table (1), in the case of a conventional backlight unit, it can be seen that even if a specific linearly polarized light is incident into the interior of the light guide plate, only 20 to 36% of the light supplied to the liquid crystal panel maintains the specific linearly polarized light.

On the other hand, as in the embodiment of the present invention, by forming a dot pattern 223 on the upper surface 221e of the light guide plate 220 and placing the inverted prismatic light collecting sheet 230 on the upper surface of the light guide plate 220, the backlight It can be seen that the polarization degree (= polarization retention rate) of the unit 120 is maintained at 90% or more.

Accordingly, the backlight unit 120 of the present invention can maintain the polarization characteristics of the specific linearly polarized light incident into the light guide plate 220 without changing.

Through this, by allowing light having uniform polarization characteristics to be emitted from the light guide plate 220, all the light emitted from the backlight unit 120 can be provided to the liquid crystal panel (110 in FIG. 2) without loss of light, thereby providing high luminance. Can be implemented.

In addition, table (2) below is an outgoing light flux of the upper surface 220e of the light guide plate 220 on which the dot pattern 223 is formed according to an embodiment of the present invention and comparison data thereof.

division Top exit luminous flux Conventional light guide plate 50 to 52% Light guide plate including dot prism pattern according to the first embodiment of the present invention 95% ↑

Referring to Table (2) and FIG. 5 together, in the conventional light guide plate, even if 100% of light is incident into the light guide plate from the LED assembly, the light emitted to the front of the light guide plate is only about 50 to 52%.

However, as in the embodiment of the present invention, by forming a dot pattern 223 on the upper surface 221e of the light guide plate 220 and placing the inverted prismatic light collecting sheet 230 on the upper surface of the light guide plate 220, the light guide plate ( 95% of light, which is the majority of the light incident into the interior of 220 ), is emitted to the front of the light guide plate 220.

This is an improvement of about 40% or more compared to the conventional light guide plate.

That is, in the light guide plate 220 of the present invention, the dot pattern 223 is formed on the upper surface 221e, and the inverted prismatic light collecting sheet 230 is positioned above the light guide plate 220, so that the inside of the light guide plate 220 The forward light emission rate is maximized for the light that is incident on and is totally reflected.

Accordingly, a surface light source of higher luminance is provided with the liquid crystal panel (110 in FIG. 2).

6 is a schematic cross-sectional view showing a partial cross-section of FIG. 2 modularized.

As shown, an optical sheet on the top of the reflective plate 125, the light guide plate 220, the LED assembly 129 made of the PCB 129b on which the LED 129a and the LED 129a are mounted, and the light guide plate 220 121) are stacked to form a backlight unit (120 in FIG. 3).

In addition, the backlight unit (120 in FIG. 3) and the first and second substrates 112 and 114 on the top thereof and a liquid crystal panel 110 interposed therebetween with a liquid crystal layer (not shown) are positioned, and the first 2 Polarizing plates 119a and 119b that selectively transmit only specific light are attached to the outer surfaces of each of the substrates 112 and 114.

The backlight unit (120 in FIG. 3) and the liquid crystal panel 110 are edged by the guide panel 130, and the cover bottom 150 including the horizontal surface 151 and the side surface 153 is coupled to the rear surface thereof. The top cover 140 surrounding the upper edge and the side surface of the liquid crystal panel 110 is coupled to the guide panel 130 and the cover bottom 150.

At this time, the backlight unit (120 in FIG. 3) of the present invention has a reflective polarizing film 210 between the LED 129a and the light guide plate 220 and the light incident surface 220a, so that the light emitted from the LED 129a is light efficiency. This will be improved.

Here, the reflective polarizing film 210 is formed by internally forming a polarizer having a certain polarization axis in a stacked structure of dielectric thin films having different refractive indices, or aluminum (Al), silver (Ag), and chromium having high reflective efficiency on the base film. It may be made of a wire grid polarizer in which fine linear metal patterns such as (Cr) are arranged side by side in one direction.

Light efficiency is improved through the reflective polarizing film 210 having such a configuration, and the reflective polarizing film 210 transmits some of the incident light and reflects the remaining light, and the reflected light is reproduced as scattered light. Some of the reproduced scattered light passes through the reflective polarizing film 210 again, and the remaining light is reflected again.

Therefore, since the reproduction of light is constantly repeated, the light efficiency is improved as a result.

That is, among the light emitted from the LED 129a, the first polarized light passes through the reflective polarizing film 210 and is incident into the light guide plate 220 through the light incident surface 220a of the light guide plate 220, but is perpendicular to the first polarization. One second polarized light is reflected by the reflective polarizing film 210 and then reproduced as scattered light.

Among the light reproduced as scattered light, the first polarized light passes through the reflective polarizing film 210 again, and the second polarized light is reproduced as scattered light again, thereby improving light efficiency.

At this time, the reflective polarizing film 210 has the same polarization axis as the first polarizing plate 119a attached to the lower portion of the liquid crystal panel 110, so that the first polarized light 119a transmitted through the reflective polarizing film 210 is a light guide plate ( 220) It is incident to the inside and is emitted toward the liquid crystal panel 110 as a surface light source by a number of total reflections inside the light guide plate 220, and at this time, the surface light sources emitted from the light guide plate 220 are all composed of first polarized light. The first polarizing plate 119a positioned under the panel 110 is transmitted as it is.

Accordingly, there is no light lost by the first polarizing plate 119a among the surface light sources emitted from the light guide plate 220, and high luminance can be implemented.

In particular, the backlight unit (120 in FIG. 3) of the present invention forms a dot pattern 223 on the upper surface 221e of the light guide plate 220, and the optical sheet 121 is directed toward the light guide plate 220. By including the inverted prism condensing sheet 230 in which the 231 protrudes and is arranged, the polarization characteristics of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 can be maintained.

Through this, by allowing light having uniform polarization characteristics to be emitted from the light guide plate 220, all light emitted from the backlight unit (120 in FIG. 3) can be provided to the liquid crystal panel 110 without loss of light, thereby providing high brightness. Can be implemented.

In addition, the light emission rate of the upper surface 221e of the light guide plate 220 may be improved, and thus a surface light source of higher brightness may be provided to the liquid crystal panel 110.

The present invention is not limited to the above embodiments, and various modifications may be made without departing from the scope of the present invention.

120: backlight unit
121: optical sheet
125: reflector
129: LED assembly (129a: LED, 129b: PCB)
210: reflective polarization film
220: light guide plate (221a: light incident surface, 221b: light incident surface, 221c, 221d: side, 221e: upper surface, 221f: lower surface)
223: dot pattern
230: inverted prism light collecting sheet (231: prism acid)

Claims (6)

A reflective plate, a light guide plate mounted on the upper part of the reflecting plate, a pattern provided on a lower surface, and a square dot pattern provided on an upper surface, an LED assembly arranged along the light incident surface of the light guide plate, and mounted on the light guide plate A backlight unit including an optical sheet including an inverted prismatic light collecting sheet;
And a liquid crystal panel mounted on the optical sheet of the backlight unit,
A reflective polarizing film is positioned between the light incident surface and the LED assembly,
The height of the dot pattern is 1/2±10% of the diameter,
The dot pattern is formed at a high density per unit area from the light incident surface to the light incident surface.
delete The method of claim 1,
The reflective polarizing film is made of a multilayered thin film structure in which a polarizer is embedded in a laminated structure of dielectric thin films having different refractive indices, or a liquid crystal display which is one selected from wire grid reflective polarizing films including fine metal patterns arranged side by side in one direction. .
The method of claim 1,
The plurality of dot patterns are spaced apart and distributed and arranged, and have a diameter of 10 to 500 μm.
delete The method of claim 1,
The inverted prism acid condensing sheet has a plurality of prismatic mountains protruding toward an upper surface of the light guide plate, and the plurality of prismatic mountains are formed in a strip shape in which mountains and valleys are repeated along a length direction of the LED assembly.

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