KR102243943B1 - Backlight Unit and Liquid Crystal Display Device having the same - Google Patents

Abstract

The present invention discloses a backlight unit and a liquid crystal display device having the same. The disclosed backlight unit of the present invention comprises: a light source; A light guide plate for converting light incident from the light source into a surface light source; An optical sheet disposed on the light guide plate; And a reflective plate disposed under the light guide plate, wherein the light guide plate includes a first light guide plate from which a surface light source is generated, and a first light guide plate disposed on a rear surface of the first light guide plate to supply light of uniform luminance to the first light guide plate. It characterized in that it comprises a 2 light guide plate.
The backlight unit of the present invention and a liquid crystal display device having the same are generated in the light guide plate area by disposing a second light guide plate on the rear surface of the first light guide plate generating a surface light source, and disposing an LED package in the light incident area of the second light guide plate. There is an effect of preventing the luminance unevenness phenomenon.

Description

Backlight Unit and Liquid Crystal Display Device having the same

The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit that prevents luminance non-uniformity due to a hot spot occurring in a light guide plate light incident area region, and a liquid crystal display device having the same.

The liquid crystal display device (LCD), which is advantageous for displaying moving images and has a large contrast ratio, is actively used in TVs and monitors. The optical anisotropy and polarization of liquid crystals The principle of image implementation is shown.

Such a liquid crystal display device is an essential component of a liquid crystal display panel that is bonded by interposing a liquid crystal layer between a color filter substrate and a thin film transistor (TFT) substrate. The difference in transmittance is realized by changing the orientation of the molecules.

However, since the liquid crystal display panel does not have its own light emitting element, a separate light source is required to display the difference in transmittance as an image, and for this purpose, a backlight unit with a built-in light source is arranged on the back of the liquid crystal display panel. do.

Such a backlight unit is divided into a direct type and an edge type according to the position of the light source. The direct type backlight unit places the light source under the liquid crystal display panel to directly direct light emitted from the light source. The light guide plate is disposed under the LCD panel, and the light source is disposed on at least one side of the light guide plate, so that the light guide is emitted from the light source using refraction and reflection from the light guide plate. It is a method of indirectly supplying light to the liquid crystal display panel.

Here, as the light source of the backlight unit, a fluorescent lamp such as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) has been widely used. According to the trend of lightweighting, light emitting diodes (LEDs), which have advantages in power consumption, weight, and brightness, are replacing fluorescent lamps.

In particular, a plurality of backlight units using LEDs as a light source are arranged on a printed circuit board in the form of an LED package in which the LEDs are mounted, and these are arranged in the light guide plate light incident area of the backlight unit.

Therefore, it is desirable to reduce the number of LED packages used in the backlight unit in order to cope with the recent trend toward light and thinner and shorter production costs of the liquid crystal display device.

However, if the number of LED packages is reduced, high-power LEDs must be used.In the structure of arranging the LED packages in the light-incident area of one light guide plate as in the prior art, there is a problem of luminance non-uniformity due to hot spots in the light-transmitting area of the light guide plate. have.

Therefore, in the prior art, there is a limit to reducing the number of LED packages because luminance unevenness must be considered when using high-power LEDs.

The present invention provides a backlight unit in which a second light guide plate is disposed on a rear surface of a first light guide plate that generates a surface light source, and an LED package is disposed in a light incident area of the second light guide plate, thereby preventing a luminance non-uniformity occurring in the light guide plate area, and An object thereof is to provide a liquid crystal display device having the same.

In addition, the present invention provides a backlight unit capable of implementing a surface light source having uniform luminance by arranging the first to third light guide plates on the backlight unit to secure an optical travel distance of light generated from the LED package, and a liquid crystal having the same. There is another purpose to provide a display device.

The backlight unit of the present invention for solving the problems of the prior art as described above, the light source; A light guide plate for converting light incident from the light source into a surface light source; An optical sheet disposed on the light guide plate; And a reflective plate disposed under the light guide plate, wherein the light guide plate includes a first light guide plate from which a surface light source is generated, and a first light guide plate disposed on a rear surface of the first light guide plate to supply light of uniform luminance to the first light guide plate. It characterized in that it comprises a 2 light guide plate.

In addition, the liquid crystal display device of the present invention includes a liquid crystal display panel; A light source to supply a surface light source to the liquid crystal display panel, a light guide plate that converts light incident from the light source into a surface light source, an optical sheet disposed above the light guide plate, and a reflective plate disposed below the light guide plate Backlight unit; And a lower cover accommodating the backlight unit, wherein the light guide plate includes a first light guide plate supplying a surface light source to the liquid crystal display panel, and the first light guide plate to supply light of uniform brightness to the first light guide plate. It characterized in that it comprises a second light guide plate disposed on the rear surface.

The backlight unit of the present invention and a liquid crystal display device having the same are generated in the light guide plate area by disposing a second light guide plate on the rear surface of the first light guide plate generating a surface light source, and disposing an LED package in the light incident area of the second light guide plate. There is an effect of preventing the luminance unevenness phenomenon.

In addition, the backlight unit of the present invention and a liquid crystal display having the same, by disposing first to third light guide plates on the backlight unit, secures an optical travel distance of light generated from the LED package, thereby providing a surface light source having uniform luminance. There is an effect that can be implemented.

1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention.
2 is an assembly cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention.
3A and 3B are diagrams showing structures of light guide plates disposed in a backlight unit according to a first embodiment of the present invention.
4A and 3B are diagrams illustrating a state in which a surface light source is emitted from light guide plates of a backlight unit according to the first embodiment of the present invention.
5 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention.
6A and 6B are views showing structures of light guide plates disposed in a backlight unit according to a second embodiment of the present invention.
7 is an exploded perspective view of a liquid crystal display device according to a third embodiment of the present invention.
8 is a diagram illustrating a structure of a light guide plate disposed in a backlight unit according to a third embodiment of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and the general knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to the possessor, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and thus the present invention is not limited to the illustrated matters. The same reference numerals refer to the same elements throughout the specification. In addition, in describing the present invention, when it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When'include','have', and'consist of' mentioned in the present specification are used, other parts may be added unless'only' is used. In the case of expressing the constituent elements in the singular, it includes the case of including the plural unless specifically stated otherwise.

In interpreting the constituent elements, it is interpreted as including an error range even if there is no explicit description.

In the case of a description of the positional relationship, for example, if the positional relationship of two parts is described as'upper','upper of','lower of','next to','right' Or, unless'direct' is used, one or more other parts may be located between the two parts.

In the case of a description of a temporal relationship, for example,'after','following','after','before', etc. It may also include cases that are not continuous unless' is used.

First, second, etc. are used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one component from another component. Accordingly, the first component mentioned below may be a second component within the technical idea of the present invention.

Each of the features of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be independently implemented with respect to each other or can be implemented together in an association relationship. May be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. The same reference numbers throughout the specification indicate the same elements.

1 is an exploded perspective view of a liquid crystal display according to a first embodiment of the present invention, and FIG. 2 is an assembly cross-sectional view of a liquid crystal display according to a first embodiment of the present invention.

1 and 2, the liquid crystal display device 100 according to the first embodiment of the present invention modulates the liquid crystal display panel 110, the backlight unit, and the liquid crystal display panel 110 and the backlight unit. It includes a panel guide 130, a lower cover 230, and an upper cover 140 for.

The liquid crystal display 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.

Here, although not shown in the drawing, a plurality of gate lines and data lines cross each other to define pixels on the inner surface of the first substrate 112, which is usually called a lower substrate or an array substrate, under the premise of an active matrix method. A thin film transistor (TFT) is provided 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 substrate, as an example corresponding to each pixel, a color filter of red (R), green (G), and blue (B) colors, and each of these A black matrix covering non-display elements such as gate lines, data lines, and thin film transistors, and transparent common electrodes covering them are provided. Here, when the liquid crystal display is in the IPS (In-Plane Switching) mode or the FFS (Fringe Field Switching) mode, the transparent common electrode may be formed on the first substrate 112.

In addition, first and second polarizing plates 119a and 119b that selectively transmit only specific light are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

In addition, a driver integrated circuit (IC) 116 is mounted on the first substrate 112 of the liquid crystal display panel 110, and the driving circuit 116 is electrically connected to the flexible circuit board 117. do.

In particular, the flexible circuit board 117 may be properly folded and adhered to the rear surface of the lower cover 230 by passing through the sidewall 200 of the panel guide 130 or the sidewall 200 of the lower cover 230 during the modularization process.

Accordingly, in the liquid crystal display panel 110 having the above-described structure, the driving signal (gate driving signal, data driving signal, common voltage, etc.) of the driving circuit 116 transmitted through the flexible circuit board 117 is applied to each gate line. Through the data line, it is transmitted to the corresponding pixel electrode, and the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, indicating a difference in transmittance.

A backlight unit that supplies light to display a difference in transmittance as an image is provided on the rear surface of the liquid crystal display panel 110.

The backlight unit includes a light source housed in the lower cover 230, a light guide plate 123 supplying a surface light source to the liquid crystal display panel 110, a reflective plate 125 disposed on a lower surface of the light guide plate 123, And a plurality of optical sheets 121 disposed on the upper surface of the light guide plate 123.

The light source includes an LED package 150 on which LEDs are mounted and a printed circuit board 151 on which the LED package 150 is mounted, and the light guide plate 123 corresponds to the liquid crystal display panel 110 to provide a surface light source. And a second light guide plate 123b disposed between the first light guide plate 123a to be emitted and the rear surface of the first light guide plate 123a and the lower cover 230.

In addition, the reflecting plate 125 includes first and second reflecting plates 125a and 125b, the first reflecting plate 125a is attached to the rear surface of the first light guide plate 123a, and the second reflecting plate 125b ) Is attached to the rear surface of the second light guide plate 123b.

When the light reflection patterns are not formed on the lower surface of the second light guide plate 123b, the light supplied to the light incident part of the second light guide plate 123b does not come out to the rear surface of the second light guide plate 123b, and total reflection only inside the light guide plate 123b. Because it is formed, the second reflector 125b may not be attached.

Accordingly, the first reflective plate 125a is disposed between the first light guide plate 123a and the lower cover 230, and the second reflective plate 125b includes the second light guide plate 123b and the lower cover 230. ) Are placed between.

The second light guide plate 123b is formed to be narrower than the width of the first light guide plate 123a and is stacked on the rear surface of the first reflecting plate 125a attached to the first light guide plate 123a. Accordingly, the printed circuit board 151 on which the LED package 150 is mounted is disposed in front of the light incident part of the second light guide plate 123b disposed on the rear surface of the first light guide plate 123a.

Accordingly, in the present invention, the light source composed of the LED package 150 and the printed circuit board 151 is disposed between the first light guide plate 123a and the lower cover 230.

In addition, the light generated from the light source is not directly incident on the first light guide plate 123a, but is incident on the light incident part of the second light guide plate 123b, and then the first light guide plate 123a from the second light guide plate 123b. ) Is supplied to the first light guide plate 123a while undergoing a number of total reflection processes. In this way, the light that travels through the second light guide plate 123b and the first light guide plate 123a emits surface light from the first light guide plate 123a in the upper direction in which the liquid crystal display panel 110 is disposed.

The light guide plate 123 of the present invention may include a pattern of a specific shape on the rear surface to supply a uniform surface light source. The pattern can be configured in various ways such as an elliptical pattern, a polygon pattern, and a hologram pattern to guide the light incident into the light guide plate 123. Such a pattern is the light guide plate. It may be formed on the lower surface of 123 by a printing method or an injection method.

As mentioned above, patterns may not be formed on the rear surface of the second light guide plate 123b.

In the present invention, the light guide plate 123 is composed of first and second light guide plates 123a and 123b, and since they are stacked, the patterns are formed in the entire area of the rear surface of the first light guide plate 123a and the second light guide plate ( 123b) can be formed on the back and front.

In addition, in the present invention, since the light incident on the second light guide plate 123b proceeds to the first light guide plate 123a while going through a total reflection process, the first light guide plate 123a and the first light guide plate 123a overlap. Reflective films 126 are disposed on side surfaces of the second light guide plate 123b.

The reflective film 126 has one edge attached to the upper edge of the first light guide plate 123a, and the other edge is attached to the rear edge of the second light guide plate 123b disposed under the first light guide plate 123a. Attached. Accordingly, the reflective film 126 has a side surface (light-incident portion) of the first light guide plate 123a, a side surface of the first reflective plate 125a, and a side surface of the second light guide plate 123b (light-exit portion) that are formed in the same plane. ) And the second reflector 125b.

The reflective film 126 may be formed by reflective coating or mirror coating. For example, a reflective film may be formed by coating methods such as aluminum (Al) deposition, silver (Ag) reflective ink printing, e-beam deposition, or the like.

Accordingly, the light incident through the light incidence portion of the second light guide plate 123b proceeds while being totally reflected in the second light guide plate 123b, and then exits through the light-exiting portion on the edge side, and the emitted light is transmitted through the reflective film 126 ) Is reflected from the inner surface of the first light guide plate 123a, and proceeds to the light incident part (side surface) of the first light guide plate 123a.

Accordingly, in the present invention, since the light incident from the LED package 150 proceeds through the second light guide plate 123b and the first light guide plate 123a, sufficient optical interference is made, and the first light guide plate 123a is uniform without light spots. There is an effect that can emit one sided light source.

The plurality of optical sheets 121 mounted on the light guide plate 123 diffuses or condenses the light converted into a surface light source by the light guide plate 123 so that a more uniform surface light source is incident on the liquid crystal display panel 110. do.

The plurality of optical sheets 121 may include a diffusion sheet for diffusing light, a prism sheet for condensing light, and a protective sheet serving as an auxiliary role for protecting the prism sheet and diffusing light.

Therefore, in the present invention, as in the prior art, since the LED package 150 generating light is not disposed on the side of the first light guide plate 123a, but is disposed in front of the light incident part of the second light guide plate 123b on the rear surface, In the first light guide plate 123a generating the surface light source, there is an effect that a light spot defect does not occur.

In addition, although not shown in the drawing, slit patterns are formed in the light-incident portion area of the second light guide plate 123b disposed to face the LED package 150 so that a light spot by the light generated from the LED package 150 Can be further reduced.

The liquid crystal display panel 110 and the backlight unit described above are modularized through the upper cover 140, the panel guide 130, and the lower cover 230.

The panel guide 130 has a rectangular frame shape and covers the edges of the backlight unit mounted on the liquid crystal display panel 110 and the lower cover 230.

The upper cover 140 is opened in a rectangular frame shape in which the cross section is bent in a "L" shape so as to cover the front and side edges of the liquid crystal display panel 110 to display an image implemented in the liquid crystal display panel 110. To be able to.

The backlight unit of the present invention and a liquid crystal display device having the same are generated in the light guide plate area by disposing a second light guide plate on the rear surface of the first light guide plate generating a surface light source, and disposing an LED package in the light incident area of the second light guide plate. There is an effect of preventing the luminance unevenness phenomenon.

3A and 3B are views showing the structure of light guide plates disposed in the backlight unit according to the first embodiment of the present invention, and FIGS. 4A and 3B are diagrams showing the structure of the light guide plates of the backlight unit according to the first embodiment of the present invention. It is a diagram showing a state in which the surface light source is emitted.

3A to 4B, the light guide plate used in the liquid crystal display according to the first embodiment of the present invention is divided into a first light guide plate 123a and a second light guide plate 123b, and the second light guide plate 123b is The area and width are narrower than that of the first light guide plate 123a.

Assuming that the first light guide plate 123a has a width in a first direction and a width in a second direction, the width in the first direction and the width in the second direction are the same, or the width in one direction is different. It can be formed longer than the width.

In the present invention, it is defined as the width in a direction in which light incident from a light source travels or in a parallel direction. Accordingly, it is preferable that the second light guide plate 123b has a smaller width of the first light guide plate 123a and the second light guide plate 123b.

Because, when the light source is disposed in the light-incident area of the second light guide plate 123b overlapping the rear surface of the first light guide plate 123a, the surface light source emitted to the upper surface of the first light guide plate 123 does not show a light spot defect. Because not.

In addition, it is preferable that the width of the first light guide plate 123a and the width of the second light guide plate 123b in the direction perpendicular to the direction in which the light travels are the same. This is because the light loss can be minimized if the emission part of the second light guide plate 123b and the incidence part of the first light guide plate 123a are identical to each other.

In addition, the second light guide plate 123b is disposed on one side of the rear surface of the first light guide plate 123a, so that one side of the second light guide plate 123b and one side of the first light guide plate 123a form the same plane. . That is, the light exit portion of the second light guide plate 123b and the light input portion of the first light guide plate 123a form the same plane.

In addition, a reflective film 126 is disposed so as to surround one side of the first and second light guide plates 123a and 123b, so that the light emitted from the side surface (the light exit part) of the second light guide plate 123b is the reflective film ( After the direction is changed by 126, it is incident on the side surface (light incident part) of the first light guide plate 123a.

In FIGS. 3A and 3B, only one LED package 150 is used as a light source of the backlight unit. Although light mixing (interference) is not completely performed in the second light guide plate 123b, the second light guide plate 123b After a distance equal to the width, it can be seen that light of uniform luminance is supplied to the entire area of the light incident part of the first light guide plate 123a.

That is, it can be seen that light of uniform luminance without a light spot is incident on the first light guide plate 123a through the light incident part.

In FIGS. 4A and 4B, when three light sources LS are used in the backlight unit, the light source may be configured as an LED package. Unlike in the prior art, the light source LS is disposed in the light incident area of the second light guide plate 123b on the rear surface of the first light guide plate 123a, so that the light traveling in the upper direction of the light source LS is the second light guide plate. Since it must pass through 123b and the rear and upper surfaces of the first light guide plate 123a, the luminance non-uniformity phenomenon due to the light spot does not occur in the region of the first light guide plate 123a corresponding to the region where the light source LS is disposed.

The same effect occurs in Figs. 3A and 3B.

Although shown in the drawings, reference numeral 125a is a first reflecting plate, 125b is a second reflecting plate, and 126 is a reflective film, which is not described. The reflective film 126 is fixed on a second reflective plate 125b attached to an upper surface of one side of the first light guide plate 123a and a rear surface of the second light guide plate 123b.

In addition, one side surfaces of the first light guide plate 123a, the first reflective plate 125a, the second light guide plate 123b, and the second reflector 125b form the same plane, and the reflective film 126 is a second light guide plate. It can be seen that the light emitted from one side of 123b is supplied to the light incident part of the first light guide plate 123a without loss.

Accordingly, as in FIGS. 4A and 4B, three light sources LS of the backlight unit are used, or in the case of a high-power light source, even if only one LED package 150 is used as in FIGS. 3A and 3B. In the present invention, there is an effect of removing a luminance non-uniformity phenomenon caused by a light spot.

5 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention, and FIGS. 6A and 6B are views showing structures of light guide plates disposed in a backlight unit according to a second embodiment of the present invention.

The second embodiment of the present invention has the same structure as the structure of the first embodiment of the present invention, except that the structure of the light guide plate is different. Accordingly, among the constituent units described in the second embodiment, the same constituents as those of the first embodiment have the same function, so refer to this, and a description will be made focusing on the distinguished parts here.

5 to 6B, a liquid crystal display device 300 according to a second embodiment of the present invention modulates a liquid crystal display panel 310, a backlight unit, and a liquid crystal display panel 310 and a backlight unit. It includes a panel guide 330, a lower cover 430, and an upper cover 340 for.

The liquid crystal display panel 310 includes first and second substrates 312 and 314, and first and second polarizing plates 319a and 319b are attached to an outer surface thereof, respectively.

In addition, a driver integrated circuit (IC) is mounted on the first substrate 312 of the liquid crystal display panel 310, and the driving circuit 316 is electrically connected to the flexible circuit board 317. do.

In particular, the flexible circuit board 317 may be properly folded and adhered to the rear surface of the lower cover 430 by passing through the sidewall 400 of the panel guide 330 or the sidewall 400 of the lower cover 430 during the modularization process.

The backlight unit includes a light source housed in the lower cover 430, a light guide plate 323 supplying a surface light source to the liquid crystal display panel 310, a reflective plate 325 disposed under the light guide plate 323, and And a plurality of optical sheets 321 disposed on the upper surface of the light guide plate 323.

The light source includes an LED package 350 on which LEDs are mounted and a printed circuit board 351 on which the LED package 350 is mounted, and the light guide plate 323 corresponds to the liquid crystal display panel 310 to provide a surface light source. The first light guide plate 323a, the second light guide plate 323b disposed between the rear surface of the first light guide plate 323a and the lower cover 430, and a side surface (light incident part) of the first light guide plate 323a. And a third light guide plate 323c having a semicircular cross-section so as to contact the side surface (light exit portion) of the second light guide plate 323b.

In the third light guide plate 323c, a region corresponding to the side surfaces (light-incident portion and light-exit portion) constituting the same plane of the first and second light guide plates 323a and 323b is formed in a planar structure, and the other side is a semicircular cross-section. It has a curved portion with In addition, the third light guide plate 323c is formed in a bar type structure parallel to the side surfaces of the first and second light guide plates 323a and 323b.

In addition, the reflecting plate 325 includes first, second and third reflecting plates 325a, 325b, 325c, and the first reflecting plate 325a is attached to the rear surface of the first light guide plate 323a, The second reflecting plate 325b is in contact with the rear surface of the first reflecting plate 325a attached to the rear surface of the second light guide plate 323b. The third reflective plate 325c is attached to the curved portion of the third light guide plate 323c.

That is, as shown in the drawing, the third light guide plate 323c includes side surfaces of the first and second light guide plates 323a and 323b (the light incident part of the second light guide plate and the light exit part of the second light guide plate) and one side surface. It is in contact, and the other side is formed in a semi-cylindrical structure having a predetermined curvature. A third reflecting plate 325c is attached to the other side of the third light guide plate 323c in the form of a film along a curved surface.

In this way, when one side of the third light guide plate 323c contacts the light incident part of the first light guide plate 323a and the light exit part of the second light guide plate 323b, light emitted from the second light guide plate 323b is There is an effect of being incident on the third light guide plate 323c without loss and being incident on the light incident portion of the first light guide plate 323a.

In addition, the first reflective plate 325a is disposed between the first light guide plate 323a and the lower cover 430, and between the first light guide plate 323a and the second light guide plate 323b, and the second reflective plate 325b is disposed between the second light guide plate 323b and the lower cover 430.

The second light guide plate 323b is formed to be narrower than the width of the first light guide plate 323a, and is attached to a rear area of the first reflecting plate 325a. Accordingly, the printed circuit board 351 on which the LED package 350 is mounted is disposed in front of the light incident part of the second light guide plate 323b attached to the rear surface of the first light guide plate 323a.

Accordingly, the light source composed of the LED package 350 and the printed circuit board 351 is disposed between the first light guide plate 323a and the lower cover 430.

In addition, the light generated from the light source is not directly incident on the first light guide plate 323a, but is incident on the light incident part of the second light guide plate 323b, and then the third light guide plate 323c from the second light guide plate 323b. ) And the first light guide plate 323a through several total reflection processes, and are supplied to the first light guide plate 323a.

The light incident on the third light guide plate 323c proceeds while undergoing total internal reflection, and the third reflecting plate 325c attached to the curved portion of the third light guide plate 323c reflects the light lost through the curved portion and reflects the light. Light proceeds to the light incident portion of the first light guide plate 323a.

Although not shown in the drawing, an adhesive layer having high light transmittance may be further formed in a region in which the third light guide plate 323c and the side surfaces (light-incident portion and light-exit portion) of the third light guide plate 323c and the first and second light guide plates 323a and 323b contact each other. have.

As described above, in the present invention, while light incident from the LED package 350 proceeds in the order of the second light guide plate 323b, the third light guide plate 323c, and the first light guide plate 323a, sufficient optical interference is made to the first light guide plate. There is an effect of being able to emit a uniform surface light source without luminance unevenness caused by light spots at (323a).

That is, the backlight unit of the present invention and a liquid crystal display having the same, by arranging the first to third light guide plates on the backlight unit, secures the optical travel distance of light generated from the LED package, and provides a surface light source having uniform luminance. There is an effect that can be implemented.

7 is an exploded perspective view of a liquid crystal display device according to a third embodiment of the present invention, and FIG. 8 is a view showing a structure of a light guide plate disposed in a backlight unit according to a third embodiment of the present invention.

In the third embodiment of the present invention, the structure of the light guide plate and the reflector plate is changed based on the first embodiment. Therefore, for portions not described herein, refer to the first embodiment.

7 and 8, a liquid crystal display device 500 according to a third embodiment of the present invention includes a liquid crystal display panel 110, a backlight unit, a panel guide 130, a lower cover 230, and an upper cover. Includes 140.

The backlight unit includes a light source housed in the lower cover 230, a light guide plate 423 supplying a surface light source to the liquid crystal display panel 110, a reflective plate 425 disposed on a lower surface of the light guide plate 423, And a plurality of optical sheets 121 disposed on the upper surface of the light guide plate 423.

The light guide plate 423 includes a first light guide plate 423a, a second light guide plate 423b, and a bent portion 423c connecting the first and second light guide plates 423a and 423b, and the first light guide plate ( 423a), the second light guide plate 423b, and the bent portions 423c are integrally formed.

A first reflecting plate 425a may be disposed on the rear surface of the first light guide plate 423a, and a second reflecting plate 425b may be disposed on the rear surface of the second light guide plate 423b. In addition, a mirror film 426 may be disposed on the bent portion 423c.

Light reflection patterns may be formed on a lower surface of the first light guide plate 423a, and light reflection patterns may be selectively formed on a lower surface of the second light guide plate 423b. When light reflection patterns are formed on the lower surface of the second light guide plate 423b, the second reflective plate 425b is attached to the rear surface of the second light guide plate 423b.

Accordingly, the first reflective plate 425a is disposed between the first light guide plate 423a and the lower cover 230 and between the first light guide plate 423a and the second light guide plate 423b, and the second reflective plate ( 425b is disposed between the second light guide plate 423b and the lower cover 230.

The second light guide plate 423b is formed to be narrower than the width of the first light guide plate 423a, and is stacked on the rear surface of the first reflecting plate 425a attached to the first light guide plate 423a. Accordingly, the printed circuit board 151 on which the LED package 150 is mounted is disposed in front of the light incident part of the second light guide plate 423b disposed on the rear surface of the first light guide plate 423a.

In addition, as shown in FIG. 8, the bent portion 423c of the light guide plate 423 used in the third embodiment of the present invention has a surface having a first curved surface R1 and a second curved surface R2. Have. The first and second curved surfaces R1 and R2 may have different values.

In addition, at least two curvature surfaces may be formed in the bent portion 423c of the light guide plate 423, and curvature values of these curvature surfaces may have different values or alternatively have different values or the same value. I can.

The first curved surface R1 has a curvature value capable of totally reflecting light emitted from the light exit portion of the second light guide plate 423b without loss to the light incident portion of the first light guide plate 423a, and the second curved surface (R2) indicates that the light emitted from the first light guide plate 423b is totally reflected on the second curved surface R2 formed on the bent portion 423c to a deeper area inside the first light guide plate 423a. It has a curvature value through which the reflected light can travel.

Therefore, it is preferable that the curvature value of the second curvature surface R2 is larger than the curvature value of the first curvature surface R1.

A reflective film 426 may be attached to the first and second curved surfaces R1 and R2 of the bent portion 423c. However, if there is no total reflection characteristic of the second curved surface R2 and no light leaking to the upper surface, the reflective film 426 may be attached only to the first curved surface R1.

In particular, in the third embodiment of the present invention, since the light guide plate 423 is integrally formed, the light emitted from the second light guide plate 423b passes through the bent portion 423c to proceed to the first light guide plate 423a without loss of light. There is an effect.

In addition, in the present invention, since the light incident from the LED package 150 proceeds to the second light guide plate 423b and the first light guide plate 423a, sufficient optical interference is made, and the first light guide plate 423a is uniform without light spots. There is an effect that can emit one sided light source.

The plurality of optical sheets 121 mounted on the light guide plate 423 diffuses or condenses the light converted into a surface light source by the light guide plate 423 so that a more uniform surface light source is incident on the liquid crystal display panel 110. do.

In the backlight unit according to the third embodiment of the present invention and a liquid crystal display device having the same, a second light guide plate is bent and disposed on a rear surface of a first light guide plate generating a surface light source, and an LED package is disposed in the light incident area of the second light guide plate. By arranging is, there is an effect of preventing a luminance unevenness phenomenon occurring in the light guide plate region.

110: liquid crystal display panel 130: panel guide
150: LED package 151: printed circuit board
121: optical sheet 230: lower cover
123: light guide plate 125: reflector
123a: first light guide plate 123b: second light guide plate
125a: first reflector 125b: second light guide plate

Claims (21)

Light source;
A light guide plate for converting light incident from the light source into a surface light source;
An optical sheet disposed on the light guide plate; And
Including a reflector disposed under the light guide plate,
The light guide plate includes a first light guide plate from which a surface light source is generated, and a second light guide plate disposed on a rear surface of the first light guide plate to supply light of uniform luminance to the first light guide plate,
The light source is disposed on a rear surface of the first light guide plate and faces one side of the second light guide plate,
The second light guide plate includes a light-exiting part formed on the other side opposite to the side facing the light source,
A backlight unit in which a light exit part of the second light guide plate opposite to a side surface of the second light guide plate facing the light source is disposed on the same plane as the light input part of the first light guide plate.
The backlight unit of claim 1, wherein a width of the second light guide plate is smaller than a width of the first light guide plate.
delete delete The backlight unit of claim 1, further comprising a reflective film surrounding a light-incident portion of the first light guide plate and a light-exit portion of the second light guide plate.
The method of claim 1, wherein the reflecting plate comprises a first reflecting plate disposed on a rear surface of the first light guide plate, and a second reflecting plate disposed on a rear surface of the second light guide plate,
The light source is a backlight unit that directly faces a rear surface of the first reflector.
The backlight unit of claim 1, further comprising a third light guide plate attached to a light incident part of the first light guide plate and a light output part of the second light guide plate.
The method of claim 7, wherein a curved portion is formed on one side of the third light guide plate opposite to the light incident part of the first light guide plate and the light output part of the second light guide plate,
The backlight unit further comprises a third reflector attached to the curved portion of the third light guide plate.
The backlight unit of claim 1, wherein the first light guide plate and the second light guide plate are integrally formed.
The backlight unit of claim 9, wherein first and second curved surfaces having different curvature values are formed at a bent portion connecting the first and second light guide plates.
A liquid crystal display panel;
A light source to supply a surface light source to the liquid crystal display panel, a light guide plate that converts light incident from the light source into a surface light source, an optical sheet disposed above the light guide plate, and a reflective plate disposed below the light guide plate Backlight unit; And
Including a lower cover accommodating the backlight unit,
The light guide plate includes a first light guide plate for supplying a surface light source to the liquid crystal display panel, and a second light guide plate disposed on a rear surface of the first light guide plate to supply light of uniform luminance to the first light guide plate,
The light source is disposed on a rear surface of the first light guide plate and faces one side of the second light guide plate,
The second light guide plate includes a light exit part having another side opposite to one side facing the light source,
A liquid crystal display device in which a light exit part of the second light guide plate opposite to a side surface of the second light guide plate facing the light source is disposed on the same plane as the light input part of the first light guide plate.
The liquid crystal display device of claim 11, wherein a width of the second light guide plate is smaller than a width of the first light guide plate.
delete delete 12. The liquid crystal display of claim 11, wherein the backlight unit further comprises a reflective film surrounding a light incident portion of the first light guide plate and a light exit portion of the second light guide plate.
The method of claim 11, wherein the reflecting plate comprises a first reflecting plate disposed on a rear surface of the first light guide plate, and a second reflecting plate disposed on a rear surface of the second light guide plate,
The light source is a liquid crystal display device that directly faces a rear surface of the first reflector.
The liquid crystal display device of claim 11, wherein the backlight unit further comprises a third light guide plate attached to a light incident part of the first light guide plate and a light output part of the second light guide plate.
The method of claim 17, wherein a curved portion is formed on one side of the third light guide plate opposite to the light incidence part of the first light guide plate and the light-out part of the second light guide plate,
The backlight unit further includes a third reflector attached to the curved portion of the third light guide plate.
The method of claim 16, wherein the first reflecting plate is disposed between the first light guide plate and the lower cover, the second reflecting plate is disposed between the second light guide plate and the lower cover, and the light source is disposed between the first reflecting plate and the lower cover. A liquid crystal display device disposed between the lower cover.
The liquid crystal display device of claim 11, wherein the first light guide plate and the second light guide plate are integrally formed.
21. The liquid crystal display of claim 20, wherein first and second curved surfaces having different curvature values are formed at a bent portion connecting the first light guide plate and the second light guide plate.

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