KR20120063931A - Liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a lightweight and thin direct type liquid crystal display device.
A feature of the present invention is to position a light guide plate on top of a plurality of LEDs arranged under the liquid crystal panel, and insert the LED into a groove formed in the bottom surface of the light guide plate.
Through this, backlight division driving may be implemented, and contrast ratio may be improved, and a more vibrant image may be realized.
In addition, since the light emitted from the LED is incident inside the light guide plate and spreads evenly over a wide area, the color mixing space in the backlight unit can be substantially increased, so that the LED mura does not occur. A liquid crystal display device can be implemented.

Description

[0001] Liquid crystal display device [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a lightweight and thin direct type liquid crystal display device.

Liquid crystal display devices (LCDs), which are used for TVs and monitors due to their high contrast ratio and are advantageous for displaying moving images, are characterized by optical anisotropy and polarization of liquid crystals. The principle of image implementation by

Such a liquid crystal display is an essential component of a liquid crystal panel bonded through a liquid crystal layer between two side-by-side substrates, and realizes a difference in transmittance by changing an arrangement direction of liquid crystal molecules with an electric field in the liquid crystal panel. do.

However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required in order to display the difference in transmittance as an image. To this end, a backlight including a light source is disposed on the back of the liquid crystal panel.

The backlight unit uses a Cold Cathode Fluorescent Lamp (CCFL), an External Electrode Fluorescent Lamp, and a Light Emitting Diode (LED) as a light source.

Among them, LEDs are particularly widely used as light sources for displays with features such as small size, low power consumption, and high reliability.

Meanwhile, a general backlight unit is classified into a direct type method and an edge type method according to the arrangement of lamps. In the edge type method, one or a pair of light sources is provided with one or two or two pairs of light guide plates. The light source has a structure in which both sides of the light guide plate are disposed, and the direct type has a structure in which several light sources are disposed below the liquid crystal panel.

1 is a cross-sectional view of a liquid crystal display including a backlight of a general direct type type using LED as a light source.

As shown in the drawing, a general liquid crystal display device includes a liquid crystal panel 10 including first and second substrates 12 and 14 and a backlight unit 20 behind the liquid crystal panel 10.

Here, the backlight unit 20 includes a reflector plate 22, and a plurality of LEDs 29a are arranged side by side on an upper surface thereof, and a diffuser plate 24 and an optical sheet 26 are disposed on the LEDs 29a. Is located.

At this time, light emitted from two or three LEDs 29a adjacent to each other overlaps and mixes with each other and then enters the liquid crystal panel 10 to provide a surface light source.

The backlight unit 20 and the liquid crystal panel 10 are modularized through the top cover 40, the support main 30, and the cover bottom 50. That is, the edges of the liquid crystal panel 10 and the backlight unit 20 are formed. The top cover 40 covering the front edge of the liquid crystal panel 10 and the cover bottom 50 covering the back surface of the backlight unit 20 in the state in which the support frame 30 having the rectangular frame shape are coupled are supported in front and rear, respectively. 30) is integrated through the medium.

In addition, reference numerals 19a and 19b denote polarizers attached to the front and rear surfaces of the liquid crystal panel 10 to control the polarization direction of light, respectively.

The direct type backlight unit 20 sequentially turns on / off the plurality of LEDs 29a for more vivid image expression, thereby supplying light to specific areas of the liquid crystal panel 10. The backlight dividing driving method may be implemented.

As a result, the contrast ratio may be improved by making the bright image brighter or the dark image darker, thereby realizing a more vibrant image.

On the other hand, the liquid crystal display device has recently been increasingly used as a portable computer, a desktop computer monitor and a wall-mounted television, and has been actively studied for a thin liquid crystal display device having a large display area.

Therefore, the liquid crystal display is thin by reducing the width of the backlight unit 20 called an optical gap or air gap, that is, the distance A between the LED 29a and the diffusion plate 24. Attempts have been made to provide a device.

However, in order to supply the high quality surface light source, which is the most important role of the backlight unit 20, to the liquid crystal panel 10, various optical designs for this purpose are considered, and one of them is the LED 29a and the diffuser plate 24. Maintaining the gap A between them is an important factor.

In particular, in the case of the LED 29a having a certain directivity angle, since light emitted from two or three LEDs 29a neighboring each other overlaps and is mixed with each other, the LED 29a is incident on the liquid crystal panel 10 to provide a surface light source. When the distance A between the 29a and the diffuser plate 24 is small, a hot spot occurs in an area corresponding to the LED 29a, and between the LED 29a and the LED 29a adjacent thereto. There is a dark portion in which the light emitted from the LED 29a does not overlap and mix with each other.

As a result, an LED mura phenomenon occurs, and furthermore, a problem of deterioration of display quality of the liquid crystal display device due to luminance unevenness is caused.

Therefore, such a direct type has a limitation in thinning, and is mainly used in a liquid crystal display device where brightness is more important than a screen thickness, and an edge type that can be thinner than a direct type has the same thickness as a notebook PC or a monitor PC. It is mainly used in the liquid crystal display device that is important.

2 is a cross-sectional view of a liquid crystal display including a general edge type backlight unit using LED as a light source.

As shown in the drawing, the LCD including the backlight unit 20 of the general edge type includes a liquid crystal panel 10 and a backlight unit 20, a support main 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 interposed therebetween.

The backlight unit 20 is provided behind the liquid crystal panel 10.

The backlight unit 20 includes an LED assembly 29 arranged along at least one edge length direction of the support main 30, a white or silver reflecting plate 22 seated on the cover bottom 50, and the reflecting plate ( 22, a light guide plate 23 seated on the top plate, and a diffuser plate 24 and an optical sheet 26 positioned at an upper portion thereof.

The liquid crystal panel 10 and the backlight unit 20 have a top cover 40 surrounding the top edge of the liquid crystal panel 10 and a back surface of the backlight unit 20 in a state where the edges are surrounded by the support main 30 having a rectangular frame shape. Cover cover 50 to cover each is coupled in front and rear are integrated through the support main 30 as a medium.

In addition, reference numerals 19a and 19b denote polarizers attached to the front and rear surfaces of the liquid crystal panel 10 to control the polarization direction of light, respectively.

At this time, the LED assembly 29 is mounted on the LED 29a is spaced apart from the LED PCB (printed circuit board: 29b, hereinafter, PCB) at a predetermined interval, the light emitted from the LED assembly 29 is a light guide plate (23). After being incident on the light incident surface of the light emitting surface, the light is refracted toward the liquid crystal panel 10, and is more uniform while passing through the diffuser plate 24 and the optical sheet 26 together with the light reflected by the reflecting plate 22. It is processed into a high quality surface light source and supplied to the liquid crystal panel 10.

However, in the liquid crystal display device including the edge type backlight unit 20, the LED assembly 29 is disposed on one side of the light guide plate 23, and the light is distributed to the entire surface using the light guide plate 23. By supplying a light source to the liquid crystal panel 10, it is very difficult to supply light to a specific region of the liquid crystal panel 10.

That is, the edge type backlight 20 is difficult to divide the backlight driving method.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide a liquid crystal display device that is thin and capable of local dimming.

Through this, the second object is to improve the contrast ratio and reduce the power consumption of the backlight unit.

Further, a third object of the present invention is to prevent a problem such as LED mura from occurring, and a fourth object of the present invention is to prevent a problem of deterioration of display quality due to uneven brightness of the liquid crystal display device.

According to an aspect of the present invention, there is provided a liquid crystal display comprising: a liquid crystal panel; A plurality of PCBs arranged on the rear surface of the liquid crystal panel at regular intervals; A plurality of LEDs mounted on the plurality of PCBs at predetermined intervals; A reflection plate including a plurality of through holes through which the plurality of LEDs pass; A light guide plate disposed on the reflecting plate and having a groove formed therein into which a plurality of LEDs exposed through the through hole are inserted; An optical sheet is disposed on the light guide plate, and an upper surface corresponding to the groove provides a liquid crystal display device having a reflective sheet.

Here, the light guide plate corresponds to a bottom surface and the bottom surface, and consists of a top surface from which light is emitted and a side surface connecting the bottom surface and the top surface, and the groove is located and the number of the PCB on the bottom surface. A scattering pattern is formed on the upper surface of the light guide plate corresponding to the groove.

In addition, a rear pattern is formed on a surface of the lower surface except for the portion in which the groove is formed, and the width of the bottom portion of the groove is 0.5 to 3 mm larger than that of the LED.

In addition, the width of the groove becomes narrower toward the upper surface, has a trapezoidal cross-sectional shape, the width of the upper surface of the groove located in front of the light emitted from the LED is 3mm, the width of the bottom portion of the groove The depth of the groove is 1.7T, the thickness of the light guide plate is 2.5T, and the width of the reflective sheet is 5mm.

Here, the light emitted from the LED is totally reflected when the incident light is greater than the critical angle of the reflective sheet is incident into the light guide plate, and the light emitted from the LED is transmitted through the reflective sheet when it is incident below the critical angle of the reflective sheet. Is emitted.

In addition, the reflective sheet has a structure in which a white polyester film is laminated on a base of a polyethylene resin (PET) base, and a plurality of holes are formed on the front surface, and the reflective sheet is made of aluminum (Al). A reflective material including silver and silver is coated on the upper surface of the light guide plate corresponding to the groove.

As described above, by placing the light guide plate on the upper portion of the plurality of LEDs arranged in the lower portion of the liquid crystal panel according to the present invention, by inserting the LED into the groove formed on the lower surface of the light guide plate, thereby implementing a backlight split driving As a result, the contrast ratio can be improved, and a more vivid image can be realized.

In addition, since the light emitted from the LED is incident inside the light guide plate and spreads evenly over a wide area, the color mixing space in the backlight unit can be substantially increased, so that the LED mura does not occur. There is an effect that can implement a liquid crystal display device.

As a result, there is an effect of preventing a problem of deterioration of display quality due to uneven brightness of the liquid crystal display.

1 is a cross-sectional view of a liquid crystal display including a backlight of a general direct type type using LED as a light source.
2 is a cross-sectional view of a liquid crystal display including a general edge type backlight unit using LED as a light source.
3 is an exploded perspective view showing a liquid crystal display device according to an embodiment of the present invention.
4a to 4b are views showing the directing angle of light that varies depending on the presence or absence of a light guide plate on the upper part of the LED.
5 is a perspective view schematically showing a light guide plate according to a first embodiment of the present invention;
FIG. 6 is a schematic cross-sectional view of a modular display of a liquid crystal display according to a first embodiment of the present invention; FIG.
7 is a perspective view schematically showing a light guide plate according to a second embodiment of the present invention.
FIG. 8 is a schematic cross-sectional view of a modular display of a liquid crystal display according to a second exemplary embodiment of the present invention. FIG.

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

3 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

As illustrated, the liquid crystal display device 100 includes a liquid crystal panel 110, a backlight unit 120, a support main 130, a cover bottom 150, and a top cover 140.

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

At this time, although not clearly shown in the drawings under the premise of an active matrix method, a plurality of gate lines and data lines intersect on the inner surface of the first substrate 112, which is commonly referred to as a lower substrate or an array substrate, thereby defining pixels. Thin film transistors (TFTs) are provided at each intersection to be connected one-to-one with the transparent pixel electrodes formed in each pixel.

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

The printed circuit boards 118a and 118b are connected to each other along at least one edge of the liquid crystal panel 110 via a connecting member 116 such as a flexible circuit board. 150) It is flipped to the back and adhered.

Although not clearly shown in the drawings, upper and lower alignment layers (not shown) for determining the initial molecular alignment direction of the liquid crystal are interposed between the two substrates 112 and 114 of the liquid crystal panel 110 and the liquid crystal layer. In order to prevent leakage of the liquid crystal layer filled therebetween, a seal pattern is formed along edges of both substrates 112 and 114.

In this case, upper and lower polarizers (not shown) are attached to outer surfaces of the first and second substrates 112 and 114, respectively.

A backlight unit 120 for supplying light is provided on a rear surface of the liquid crystal panel 110 such that a difference in transmittance of the liquid crystal panel 110 is expressed to the outside.

The backlight unit 120 includes an LED assembly 129, a light guide plate 200, a diffusion plate 124, and an optical sheet 126 positioned on the LED assembly 129.

The LED assembly 129 described above includes a PCB 129b arranged to have a predetermined spaced space along the longitudinal inner surface of the cover bottom 150, and a plurality of LEDs 129a mounted on each of them.

Here, the plurality of LEDs 129a emit light having the colors of red (R), green (G), and blue (B), respectively, and turn on the plurality of RGB LEDs (129a) at once to generate white light by color mixing. Each LED 129a emits white light toward the light guide plate 200, including an LED chip (not shown) that emits all the colors of RGB or emits white light.

The LED 129a that implements white light may be composed of a blue LED chip (not shown) and a yellow phosphor, and the yellow phosphor is yttrium (Y) aluminum (Al) doped with cerium (Ce) having a wavelength of 530 to 570 nm. It is preferable to use YAG: Ce (T3Al5O12: Ce) series phosphor which is garnet.

In addition, an LED chip (not shown) may be used as a UVLED chip. When using the UV LED chip, the phosphor (not shown) is composed of three colors of phosphors of red (R), green (G), and blue (B). Emission color can be selected by adjusting the compounding ratio of phosphor (R), green (G), and blue (B).

In this case, the red phosphor is a YOX (Y 2 O 3: EU) -based phosphor made of yttrium oxide (Y 2 O 3) and europium (EU) compound having a 611 nm wavelength, and the green (G) phosphor is a 544 nm wavelength. Is a LAP (LaPo4: Ce, Tb) -based phosphor which is a compound of phosphoric acid (Po4), lanthanum (La), and terbium (Tb), and the blue (B) phosphor has a barium wavelength of 450 nm. It is preferable to use BAM blue (BaMgAl 10 O 17: EU) -based phosphor, which is a compound of Ba), magnesium (Mg), aluminum oxide-based material, and europium (EU).

Here, the dominant wavelength is referred to as the wavelength of the phosphor that generates the highest luminance in each of red (R), green (G), and blue (B).

The PCB 129b on which the plurality of LEDs 129a are mounted is a metal core printed circuit board having heat dissipation, and a heat sink (not shown) is provided on the back of the MCPCB 129b. Receives heat from the LED 129a can be to be emitted to the outside.

The backlight unit 120 including the LEDs 129a includes a plurality of through holes 123 through which the plurality of LEDs 129a can pass, thereby covering the PCB 129b and the cover excluding the plurality of LEDs 129a. 150 includes a white or silver reflecting plate 122 covering the entire inner surface.

In particular, the backlight unit 120 of the present invention is a direct type in which a plurality of LEDs 129a are disposed below the liquid crystal panel 110, but the light guide plate 200 is positioned above the LEDs 129a. do.

In addition, a groove 210 corresponding to the length of the PCB 129b of the LED assembly 129 is formed in the lower surface of the light guide plate 200, that is, in the groove 210. A plurality of LEDs 129a mounted on the PCB 129b are inserted.

At this time, the reflective sheet 220 is located on the upper surface corresponding to the groove 210 of the light guide plate 200, the reflective sheet 220 serves to guide the light emitted from the plurality of LED (129a).

Accordingly, some of the light emitted from the plurality of LEDs 129a passes through the reflective sheet 220 and is emitted toward the liquid crystal panel 110, and some of the light is reflected by the reflective sheet 220 to be inside the light guide plate 200. Incident.

At this time, the light incident into the light guide plate 200 is totally reflected in the light guide plate 200 to proceed in the light guide plate 200 to spread evenly to a wide area of the light guide plate 200. We will discuss this in more detail later.

In addition, a diffusion plate 124 and an optical sheet 126 are positioned on the light guide plate 200 for uniformity of luminance.

Here, the optical sheet 126 may include a diffusion sheet, at least one light collecting sheet, and the like, and may include various functional sheets such as a reflective polarizing film called a dual brightness enhancement film (DBEF).

Accordingly, the light emitted from the plurality of LEDs 129a implements a surface light source through the light guide plate 200, and the implemented surface light source passes through the diffuser plate 124 and the optical sheet 126 in turn, and then the liquid crystal panel 110. ), And the liquid crystal panel 110 displays a high brightness image to the outside.

In this case, the color mixing space of the light emitted from the plurality of LEDs 129a may be increased through the light guide plate 200, so that the dark portion may minimize the separation distance between the diffuser plate 124 and the LED 129a. It can be prevented from occurring.

In addition, even if the distance between the LED 129a and the diffusion plate 124 is reduced, it is possible to prevent the occurrence of hot spots in the area corresponding to the LED 129a, thereby preventing the occurrence of the LED mura phenomenon. have.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the support main 130, and the cover bottom 150. The top cover 140 is the top and side surfaces of the liquid crystal panel 110. A rectangular frame having a cross section bent in a shape so as to cover an edge thereof is configured to open an entire surface of the top cover 140 to display an image implemented in the liquid crystal panel 110.

In addition, the cover bottom 150, which is the basis for assembling the entire structure of the liquid crystal display device 100 by mounting the liquid crystal panel 110 and the backlight unit 120, has a rectangular plate shape and covers the cover bottom 150 with each other. It includes a pair of bar-shaped side support 128 coupled to opposite opposite edges, except for the other two edges of the cover bottom 150 bent obliquely to the same height and the inside thereof The backlight unit 120 forms a predetermined space in which the backlight unit 120 can be seated.

A support main 130 having a rectangular frame shape seated on the cover bottom 150 and surrounding the edges of the liquid crystal panel 110 and the backlight unit 120 is combined with the top cover 140 and the cover bottom 150.

Meanwhile, the top cover 140 may be referred to as a case top or a top case, the support main 130 may be referred to as a guide panel or a main support, and a mold frame, and the cover bottom 150 may be referred to as a bottom cover.

The liquid crystal display device 100 according to the present invention may be divided by each LED 129a to perform division driving. That is, in the liquid crystal display device 100 of the present invention, the LED assembly 129 may implement backlight division driving to sequentially turn on / off each of the LEDs 129a for a more vibrant image representation. have.

Here, the backlight division driving is a driving method of turning off the area corresponding to the pixel while the pixel is responding and lighting the area after the response is completed. It goes out.

By performing backlight division driving for each region through the LEDs 129a as described above, only light emitted for each region is supplied to a specific region of the liquid crystal panel 110, thereby brightening an image realized by the liquid crystal panel 110. By making the lighter or darker the darker the contrast ratio can be improved, resulting in a vivid image.

In addition, the brightness suitable for the image can be adjusted, so that the image having a dark brightness has light of dark brightness, thereby reducing the power consumption of the backlight unit 120.

In addition, since the liquid crystal display device 100 of the present invention includes the light guide plate 200 on the upper portion of the LED 129a, the color mixing space in the backlight unit 120 may be substantially increased. Even if the separation distance between the 124 and the LED 129a is minimized, it is possible to prevent the LED mura phenomenon from occurring.

4A to 4B are diagrams showing a direction of light varying depending on the presence or absence of a light guide plate on the upper part of the LED.

As shown in FIG. 4A, when there is no light guide plate on the top of the LED 129a, the light emitted from the LED 129a is directly emitted to the air. On the contrary, as shown in FIG. 4B, when the light guide plate 200 is positioned above the LED 129a and the LED 129a is inserted into the groove 210 formed in the lower surface of the light guide plate 200, the LED 129a is disposed. The light concentrated toward the front of the c) is totally reflected by the reflective sheet 220 of the light guide plate 200 to be incident into the light guide plate 200.

That is, as indicated by L1, when the light incident from the LED 129a enters the reflective sheet 220 at a critical angle or less, the light passes through the reflective sheet 220 and is emitted to the upper portion of the light guide plate 200.

As indicated by L2, some of the light emitted from the LED 129a directly enters the light guide plate 200 or is totally reflected when the light enters the reflective sheet 220 above the light guide plate 200. 200) incident inside.

As such, the light incident into the light guide plate 200 is totally reflected inside the light guide plate 200, proceeds inside the light guide plate 200, and spreads evenly to a wide area of the light guide plate 200, as indicated by L3. It is emitted to the outside throughout.

As a result, the color mixing space in the backlight unit 120 (in FIG. 3) may be increased.

Therefore, even if the separation distance between the diffusion plate (124 of FIG. 3) and the LED (129a) is minimized, the dark portion can be prevented from occurring.

In addition, even if the distance between the LED 129a and the diffusion plate 124 of FIG. 3 is reduced, hot spots can be prevented from occurring in the region corresponding to the LED 129a, thereby preventing the occurrence of the LED mura phenomenon. You can prevent it.

- First Embodiment -

5 is a perspective view schematically illustrating a light guide plate according to a first embodiment of the present invention.

As shown, the light guide plate 200 is a plastic material or polycarbonate (PC), such as polymethylmethacrylate (PMMA), an acrylic transparent resin, which is one of transparent materials capable of transmitting light. It is manufactured in flat type by series.

Here, PMMA is an acrylic resin, which is excellent in transparency, weather resistance and colorability, and induces light diffusion when light is transmitted.

The light guide plate 200 corresponds to the lower surface 200a corresponding to the LED assembly (129 of FIG. 3), the upper surface 200b corresponding to the light emitted from the light guide plate 200, and the lower surface 200a and the upper surface 200b. It consists of the side surface 200c.

In particular, the light guide plate 200 of the present invention is characterized in that the groove 210 is formed along the longitudinal direction of the light guide plate 200 on the lower surface 200a, the groove 210 is cover cover (150 in FIG. 3). ) Corresponds to the position and number of LED assemblies (129 of FIG. 3) arranged on the substrate.

That is, the groove 210 formed in the lower surface 200a of the light guide plate 200 has a plurality of LEDs (129a of FIG. 3) mounted on the PCB (129b of FIG. 3) of the LED assembly (129 of FIG. 3) inserted therein. do.

Here, the width d2 of the groove 210 may be variously formed according to the size of the LED (129a of FIG. 3), and the groove 210 may include a plurality of LEDs mounted on the PCB (129b of FIG. 3). In order to allow more light from the 129a of FIG. 3 to enter the light guide plate 200, the inner area of the groove 210 may be formed wider than that of the LED (129a of FIG. 3).

That is, it is preferable to form to have a large size of 0.5 to 3mm compared to the size of the LED (129a of FIG. 3).

And, the shape of the groove 210 thereof may be variously implemented, such as hemispherical shape, polygonal shape.

In this case, various types of scattering patterns 230a are formed on the upper surface 200b of the light guide plate 200 corresponding to the groove 210 so as to scatter light emitted from the LED (129a of FIG. 3).

Here, the scattering pattern 230a is configured in various ways such as an elliptical pattern, a polygonal pattern, a hologram pattern, and the like to guide light emitted from the LED (129a of FIG. 3). The scattering pattern 230a may be formed by a printing method or an injection method.

In addition, the light guide plate 200 of the present invention serves to guide the light emitted from the plurality of LEDs (129a of FIG. 3) by placing the reflective sheet 220 on the scattering pattern 230a. That is, the reflective sheet 220 totally reflects the light emitted from the plurality of LEDs (129a of FIG. 3) to allow the light to enter the light guide plate 200.

Therefore, some of the light emitted from the plurality of LEDs (129a of FIG. 3) is reflected by the reflecting sheet 220 positioned in front of the LEDs (129a of FIG. 3) to be incident into the light guide plate 200, and also partially Light passes through the reflective sheet 220 and is emitted toward the liquid crystal panel 110 of FIG. 3.

At this time, not all of the light emitted from the LED (129a of FIG. 3) is reflected by the reflective sheet 220, but is totally reflected when only some of the reflective sheets 220 are incident above the critical angle to enter the light guide plate 200. When incident below the critical angle, light passes through the reflective sheet 220 and is emitted toward the liquid crystal panel 110 of FIG. 3.

In addition, some light emitted from the LED (129a of FIG. 3) is directly incident to the light guide plate 200.

Here, 90% of the light emitted from the LED (129a of FIG. 3) is totally reflected by the reflective sheet 220 or directly incident into the light guide plate 200, 10% of the light emitted from the LED (129a of FIG. 3) Is transmitted through the reflective sheet 220.

Reflective sheet 220 is formed of a structure in which a highly reflective material, for example, a white polyester film is laminated on a base of a polyethylene resin (PET) base, and a plurality of holes (not shown) are formed on the front surface. Some light may be totally reflected or some light may be transmitted.

Alternatively, a reflective material having excellent reflectivity including aluminum (Al) and silver (Ag) may be coated on the upper surface 200b of the light guide plate 200 corresponding to the groove 210.

In addition, the light incident to the inside of the light guide plate 200 is incident on the surface of the lower surface 200a of the light guide plate 200 in the direction of the liquid crystal panel (110 in FIG. 3). The rear pattern 230b having a specific shape is formed.

Here, the back pattern 230b is formed to guide the light incident into the light guide plate 200. The back pattern 230b also has an elliptical pattern, a polygon pattern, and a hologram pattern. hologram pattern) and the like, and the back pattern 230b is formed on the lower surface 200a of the light guide plate 200 by a printing method or an injection method.

6 is a schematic cross-sectional view of a modular display of a liquid crystal display according to a first exemplary embodiment of the present invention.

6 is a part of a cross section cut perpendicular to the longitudinal direction of the PCB 129b.

As shown, a plurality of PCB 129b is arranged on the cover bottom 150 spaced apart from each other, each of the PCB 129b is mounted with a plurality of LEDs (129a) to form an LED assembly 129, The upper part of the LED assembly 129 is covered with a reflecting plate 122 configured with a through hole 123 to expose only the LED 129a, and the upper part of the reflecting plate 122 is exposed through the through hole 123. The light guide plate 200 is positioned so that the LED 129a is inserted into the groove 210.

The diffusion plate 124 and the optical sheet 126 are stacked on the light guide plate 200 to form a backlight unit (120 of FIG. 3).

The backlight unit (120 of FIG. 3) of the present invention forms a groove 210 into which the LED 129a can be inserted into the lower surface 200a of the light guide plate 200, and then, the LED 210 into the groove 210. By inserting the 129a, the light emitted from the LED 129a is incident into the light guide plate 200 and evenly spreads over a wide area.

 Thus, it is possible to substantially increase the color mixing space in the backlight unit (120 in FIG. 3).

Accordingly, the liquid crystal display (100 in FIG. 3) of the present invention, in order to reduce the weight (A) between the LED 129a and the diffuser plate 124 in order to reduce the weight and thickness. The light emitted from the LED 129a between the 129a may be prevented from generating dark portions that do not overlap and mix with each other.

In addition, even if the distance A 'between the LED 129a and the diffuser plate 124 is reduced, hot spots may be prevented from occurring in the region corresponding to the LED 129a.

For this reason, LED mura phenomenon is prevented from occurring.

- Second Embodiment -

7 is a perspective view schematically illustrating a light guide plate according to a second embodiment of the present invention.

As shown, the light guide plate 200 is a plastic material such as polymethylmethacrylate (PMMA) or polycarbonate (PC), which is an acrylic transparent resin, which is one of transparent materials capable of transmitting light. It is manufactured in flat type by series.

Here, PMMA is an acrylic resin, which is excellent in transparency, weather resistance and colorability, and induces light diffusion when light is transmitted.

The light guide plate 200 corresponds to the lower surface 200a corresponding to the LED assembly (129 of FIG. 3) and corresponds to the upper surface 200b and the lower surface 200a and the upper surface 200b to which light is emitted. It consists of a side (200c).

In particular, the light guide plate 200 of the present invention is characterized in that the groove 210 is formed along the longitudinal direction of the light guide plate 200 on the lower surface 200a, the groove 210 is cover cover (150 in FIG. 3). ) Corresponds to the position and number of LED assemblies (129 of FIG. 3) arranged on the substrate.

That is, the groove 210 formed in the lower surface 200a of the light guide plate 200 has a plurality of LEDs (129a of FIG. 3) mounted on the PCB (129b of FIG. 3) of the LED assembly (129 of FIG. 3) inserted therein. do.

Here, the groove 210 has a narrower width toward the upper surface 200b of the light guide plate 200 and forms a trapezoidal shape in cross section.

The width d2 of the groove 210 may be variously formed according to the size of the LED (129a of FIG. 3), and the groove 210 may include a plurality of LEDs mounted on the PCB (129 of FIG. 3). In order to inject more light from the 129a of 3 into the light guide plate 200, the inner area of the groove 210 may be formed to be wider than that of the LED (129 of FIG. 3). We will discuss this in more detail later.

And, the shape of the groove 210 thereof may be variously implemented, such as hemispherical shape, polygonal shape.

In this case, various types of scattering patterns 230a are formed on the upper surface 200b of the light guide plate 200 corresponding to the groove 210 so as to scatter light emitted from the LED (129a of FIG. 3).

Here, the scattering pattern 230a is configured in various ways such as an elliptical pattern, a polygonal pattern, a hologram pattern, and the like to guide light emitted from the LED (129a of FIG. 3). The scattering pattern 230a may be formed by a printing method or an injection method.

In addition, the light guide plate 200 of the present invention serves to guide the light emitted from the plurality of LEDs (129a of FIG. 3) by placing the reflective sheet 220 on the scattering pattern 230a. That is, the reflective sheet 220 totally reflects the light emitted from the plurality of LEDs (129 of FIG. 3) to allow the light to enter the light guide plate 200.

Therefore, some of the light emitted from the plurality of LEDs (129a of FIG. 3) is reflected by the reflecting sheet 220 positioned in front of the LEDs (129a of FIG. 3) to be incident into the light guide plate 200, and also partially Light passes through the reflective sheet 220 and is emitted toward the liquid crystal panel 110 of FIG. 3.

At this time, not all of the light emitted from the LED (129a of FIG. 3) is reflected by the reflective sheet 220, but is totally reflected when only some of the reflective sheets 220 are incident above the critical angle to enter the light guide plate 200. When incident below the critical angle, light passes through the reflective sheet 220 and is emitted toward the liquid crystal panel 110 of FIG. 3.

In addition, some light emitted from the LED (129a of FIG. 3) is directly incident to the light guide plate 200.

Here, 90% of the light emitted from the LED (129a of FIG. 3) is totally reflected by the reflective sheet 220 or directly incident into the light guide plate 200, 10% of the light emitted from the LED (129a of FIG. 3) Is transmitted through the reflective sheet 220.

Reflective sheet 220 is formed of a structure in which a highly reflective material, for example, a white polyester film is laminated on a base of a polyethylene resin (PET) base, and a plurality of holes (not shown) are formed on the front surface. Some light may be totally reflected or some light may be transmitted.

Alternatively, a reflective material (not shown) having excellent reflectivity including aluminum (Al) and silver (Ag) may be coated on the upper surface 200b of the light guide plate 200 corresponding to the groove 210.

In addition, the light incident to the inside of the light guide plate 200 is incident on the surface of the lower surface 200a of the light guide plate 200 in the direction of the liquid crystal panel (110 in FIG. 3). The rear pattern 230b having a specific shape is formed.

Here, the back pattern 230b is formed to guide the light incident into the light guide plate 200. The back pattern 230b also has an elliptical pattern, a polygon pattern, and a hologram pattern. hologram pattern) and the like, and the back pattern 230b is formed on the lower surface 200a of the light guide plate 200 by a printing method or an injection method.

FIG. 8 is a schematic cross-sectional view of a modular display of a liquid crystal display according to a second exemplary embodiment of the present invention.

8 is a part of a cross section cut perpendicular to the longitudinal direction of the PCB 129b.

As shown, a plurality of PCB 129b is arranged on the cover bottom 150 spaced apart from each other, each of the PCB 129b is mounted with a plurality of LEDs (129a) to form an LED assembly 129, The upper part of the LED assembly 129 is covered with a reflecting plate 122 configured with a through hole 123 to expose only the LED 129a, and the upper part of the reflecting plate 122 is exposed through the through hole 123. The light guide plate 200 is positioned so that the LED 129a is inserted into the groove 210.

The diffusion plate 124 and the optical sheet 126 are stacked on the light guide plate 200 to form a backlight unit (120 of FIG. 3).

The backlight unit (120 of FIG. 3) of the present invention forms a groove 210 into which the LED 129a can be inserted into the lower surface 200a of the light guide plate 200, and then, the LED 210 into the groove 210. By inserting the 129a, the light emitted from the LED 129a is incident into the light guide plate 200 and evenly spreads over a wide area.

 Thus, it is possible to substantially increase the color mixing space in the backlight unit (120 in FIG. 3).

Accordingly, the liquid crystal display (100 in FIG. 3) of the present invention, in order to reduce the weight (A) between the LED 129a and the diffuser plate 124 in order to reduce the weight and thickness. The light emitted from the LED 129a between the 129a may be prevented from generating dark portions that do not overlap and mix with each other.

In addition, even if the distance A 'between the LED 129a and the diffuser plate 124 is reduced, hot spots may be prevented from occurring in the region corresponding to the LED 129a.

For this reason, LED mura phenomenon is prevented from occurring.

Meanwhile, the widths d1 and d2 and the depth S2 of the grooves 210 of the light guide plate 200 according to the second embodiment of the present invention may be optimized through the following simulation results.

S1 S2 d1 (m) D1 (m) ① Luminance of area (cd / cm2) ② Luminance of area (cd / cm2) 3.0T 2.0T 3 5 92.27 42.51 4 6 101.25 41.31 5 7 105.98 40.69 6 8 108.71 40.09 7 9 108.56 39.26

Table 1 above is a luminance value measured corresponding to the width d1 of the upper surface of the groove 210 of the light guide plate 200 and the width D1 of the reflective sheet 220, and the grooves of the light guide plate 200 ( It can be seen that the luminance value measured corresponding to the width d1 of the upper surface of the 210 and the width D1 of the reflective sheet 220 is different.

At this time, the size of the LED 129a inserted into the groove 210 is 2 mm. As the width d1 of the upper surface of the groove 210 is narrower, the amount of light emitted toward the front of the LED 129a is reduced, and the light guide plate 200 is reduced. It can be seen that the amount of light incident into the inside increases.

Through this, as the width d1 of the upper surface of the groove 210 is narrower, the amount of light incident to the inside of the light guide plate 200 may be increased to increase the light efficiency.

That is, the groove 210 of the light guide plate 200 of the present invention is formed such that the top surface has a width d1 of 3 mm, and the width D1 of the reflective sheet 220 is preferably 5 mm.

Table 2 below is a simulation result of measuring luminance values according to the thickness S1 of the light guide plate 200 and the depth S2 of the groove 210.

S1 S2 d1 D1 ① Luminance of area (cd / cm2) ② Luminance of area (cd / cm2) 3.0T 2.0T 3 5 92.27 42.514 2.5T 1.7T 100.41 41.512 2.5T 1.5T 105.65 38.04 2.5T 1.3T 110.12 34.494

Referring to the above table (2), it can be seen that the luminance value is changed as the thickness (S2) of the light guide plate 200 is different, where the thickness (S2) of the light guide plate 200 is reduced by 0.5T, Even if the depth S2 is reduced by 0.3T, it can be seen that the difference in light efficiency is small.

That is, the light guide plate 200 of the present invention can be reduced by 0.5T compared with the thickness of the light guide plate 200 of the first embodiment.

Referring to Tables 1 and 2 so far, the thickness S1 of the light guide plate 200, the depth S2 of the grooves 210, the width d1 of the upper surface of the grooves 210, and the reflective sheet ( The optimum value of the width D1 of the 220 may be confirmed. Through this, the width d2 of the bottom of the groove 210 may be determined through the following table (3).

S1 S2 d1 (m) d2 (m) D1 (m) ① Luminance of area (cd / cm2) ② Luminance of area (cd / cm2) 2.5T 1.7T 3 3 5 100.41 41.51 3.5 100.54 44.22 4 100.96 46.11 4.5 101.67 46.94 5 102.68 47.15 5.5 103.67 46.47 6 104.45 44.87 6.5 104.83 42.66 7 104.88 40.71

Referring to Table 3 above, when the width d2 of the bottom portion of the groove 210 is 5 mm, it can be seen that the amount of light incident into the light guide plate 200 is the largest.

Therefore, the light guide plate 200 of the present invention has a thickness S1 of 2.5T, the depth S2 of the groove 210 is 1.7T, and the width d2 of the bottom portion of the groove 210 is 5 mm, and the groove 210 is formed. It is preferable that the width | variety d1 of the upper surface of () is 3 mm. The width D1 of the reflective sheet 220 is preferably the same as the width d2 of the bottom portion of the groove 210.

As described above, the backlight unit 120 of FIG. 3 of the liquid crystal display 100 of FIG. 3 according to the second exemplary embodiment of the present invention has a plurality of LEDs 129a under the liquid crystal panel 110 of FIG. 3. In the direct type in which the is arranged, the backlight division driving may be implemented, and the contrast ratio may be improved, thereby providing a more vibrant image.

In addition, the light guide plate 200 is positioned on the upper portion of the LED 129a, and after forming the groove 210 into which the LED 129a can be inserted into the bottom surface 200a of the light guide plate 200, the groove 210 is formed. By inserting the LED 129a into the interior, the light emitted from the LED 129a is incident into the light guide plate 200 and evenly spreads over a wide area.

As a result, the color mixing space in the backlight unit 120 (in FIG. 3) may be substantially increased, so that the liquid crystal display (100 in FIG. 3) of the present invention may be configured with an LED 129a for light weight and thinness. Even when the distance A 'between the diffuser plate 124 is reduced, the light emitted from the LED 129a between the LED 129a and the LED 129a adjacent to the LED 129a may be prevented from occurring. Can be.

In addition, even if the distance A 'between the LED 129a and the diffuser plate 124 is reduced, hot spots may be prevented from occurring in the region corresponding to the LED 129a.

For this reason, LED mura phenomenon is prevented from occurring.

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

122: reflector, 123: through hole
124: diffuser plate, 126: optical sheet, 129: LED assembly (129a: LED, 129b: PCB)
150: Cover Bottom
200: light guide plate (200a: lower surface, 200b: upper surface), 210: groove, 220: reflective sheet

Claims (11)

A liquid crystal panel;
A plurality of PCBs arranged on the rear surface of the liquid crystal panel at regular intervals;
A plurality of LEDs mounted on the plurality of PCBs at predetermined intervals;
A reflection plate including a plurality of through holes through which the plurality of LEDs pass;
A light guide plate disposed on the reflecting plate and having a groove formed therein into which a plurality of LEDs exposed through the through hole are inserted;
An optical sheet on the light guide plate
And a reflection sheet on an upper surface corresponding to the groove.
The method of claim 1,
The light guide plate corresponds to a bottom surface and the bottom surface, and includes a top surface from which light is emitted and a side surface connecting the bottom surface and the top surface, and the groove corresponds to the position and number of the PCB on the bottom surface. Liquid crystal display device formed by.
The method of claim 1,
The scattering pattern is formed on the upper surface corresponding to the groove.
The method of claim 1,
And a rear pattern formed on a surface of the lower surface except for the portion where the groove is formed.
The method of claim 1,
The width of the bottom of the groove is 0.5 to 3mm larger than the size of the LED liquid crystal display device.
The method of claim 1,
The groove has a narrower width toward the upper surface, and has a trapezoidal shape in cross section.
The method according to claim 6,
The width of the upper surface of the groove located in front of the light emitted from the LED is 3mm, the width of the bottom portion of the groove is 5mm, the depth of the groove is 1.7T, the thickness of the light guide plate is 2.5T, A liquid crystal display device having a width of 5 mm for the reflective sheet.
The method of claim 1,
The light emitted from the LED is totally reflected when the incident light exceeds the critical angle of the reflective sheet is incident to the inside of the light guide plate.
The method of claim 1,
And the light emitted from the LED is transmitted through the reflective sheet when the light is incident below the critical angle of the reflective sheet.
The method of claim 1,
The reflective sheet has a structure in which a white polyester film is stacked on a base of a polyethylene resin (PET) base, and a plurality of holes are formed on a front surface thereof.
The method of claim 1,
The reflective sheet is a liquid crystal display device wherein a reflective material comprising aluminum (Al) and silver (Ag) is coated on the upper surface of the light guide plate corresponding to the groove.

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