KR101593690B1 - Backlight unit and display apparatus thereof - Google Patents

Abstract

Backlight unit and a display device using the same. The backlight unit includes a light source that emits light; A plurality of light guide plates for upwardly emitting light incident on a side of the light source; And a diffusion sheet disposed on the upper side of the light guide plate and protruding in a predetermined direction. At least a part of the pattern formed on the diffusion sheet overlaps with a boundary portion between adjacent light guide plates.

Description

BACKLIGHT UNIT AND DISPLAY APPARATUS USING THE SAME

The present invention relates to a backlight unit and a display device including the same.

(PDP), Electro Luminescent Display (ELD), Vacuum Fluorescent Display (VFD), and the like have been developed in recent years in response to the demand for display devices. Display) have been studied and used.

Among them, a liquid crystal panel of an LCD includes a liquid crystal layer and a TFT substrate and a color filter substrate facing each other with the liquid crystal layer interposed therebetween. Since there is no self-luminous force, the image is displayed using light provided from the backlight unit can do.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backlight unit capable of improving the image quality of a display image and a display device using the same.

A backlight unit according to an embodiment of the present invention includes: a light source that emits light; A plurality of light guide plates for upwardly emitting light incident on the light source side; And a diffusion sheet disposed on the light guide plate and having a pattern protruding in a predetermined direction, wherein at least a part of the pattern formed on the diffusion sheet overlaps with a boundary portion between adjacent light guide plates

A backlight unit according to another embodiment of the present invention includes: a light source that emits light; A plurality of light guide plates for upwardly emitting light incident on the light source side; And a diffusion sheet disposed on the light guide plate and having a pattern protruding in a predetermined direction, wherein at least a part of the two light guide plates adjacent to each other among the plurality of light guide plates are overlapped, and at least a part of the patterns formed on the diffusion sheet And overlaps the boundary portion between the adjacent light guide plates.

The display device according to an embodiment of the present invention may include the backlight unit and a display panel positioned above the backlight unit and displaying an image using light emitted from the backlight unit, The panel is divided into a plurality of regions and the brightness of light emitted from the light guide plate corresponding to the region is adjusted according to the gray level peak value or the color coordinate signal of each of the plurality of regions.

According to an embodiment of the present invention, a modular backlight unit including a plurality of light guide plates is used to provide light to the display panel, thereby reducing the thickness of the display device and reducing local dimming or impulsive impulsive, etc., can be used to improve the contrast of the display image.

Further, by forming a protrusion pattern on the diffusion sheet so as to overlap the boundary portion between the plurality of light guide plates, light emitted from the boundary portion between the light guide plates is diffused or condensed, and a bright line or a dark line Can be reduced.

Hereinafter, the present invention will be described with reference to the accompanying drawings. Hereinafter, the embodiments may be modified into various other forms, and the technical scope of the embodiments is not limited to the embodiments described below. The embodiments are provided so that this disclosure may be more fully understood by those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

1 is an exploded perspective view of a display device according to an embodiment of the present invention.

1, a display device 1 according to the present embodiment includes a display module 200, a front cover 300 and a back cover 400 surrounding the display module 200, a display module 200, And a fixing member 500 for fixing the front cover 300 and / or the back cover 400 to the front cover 300 and / or the back cover 400.

One side of the fixing member 500 is fixed to the front cover 300 by a fastening member such as a screw and the other side of the fixing member 500 supports the display module 200 to the side of the front cover 300, The display module 200 may be fixed with respect to the display module 200.

Although the fixing member 500 is described as being formed in a plate shape elongated in one direction in the present embodiment, the fixing member 500 may not be provided, It is also possible that the back cover 300 is fixed to the front cover 300 or the back cover 400.

FIG. 2 is a cross-sectional view of an embodiment of the display module. FIG. 2 is a cross-sectional view of a portion cut along the line A-A in FIG.

2, the display module 200 includes a display panel 210 for displaying an image, a backlight unit 100 for providing light to the display panel 210, A bottom cover 110 for supporting the display panel 210 on the lower side and a panel supporter 240 for supporting the display panel 210 on the lower side and a top cover 210 for supporting the display panel 210 from above and forming the rim of the display module 200 230).

The bottom cover 110 may be formed in a box shape whose top surface is opened so that the backlight unit 100 can be housed. One side of the bottom cover 110 may be fixed to one side of the top cover 230. For example, a fastening member such as a screw penetrates the side of the display module 200, that is, the side where the bottom cover 110 and the top cover 230 are overlapped with each other so that the bottom cover 110 and the top cover 230 Can be fixed.

Although not shown in detail, the display panel 210 may include a lower substrate 211 and an upper substrate 222 that are bonded together to maintain a uniform cell gap so as to face each other, and a liquid crystal layer (not shown) interposed between the two substrates. . A plurality of gate lines and a plurality of data lines intersecting the plurality of gate lines are formed on the lower substrate 211, and a thin film transistor (TFT) may be formed on the intersections of the gate lines and the data lines. have.

Color filters may be formed on the upper substrate 212. The structure of the display panel 210 is not limited thereto, and the display panel 210 may have various structures. As another example, the lower substrate 211 may include a color filter as well as a thin film transistor. In addition, the display panel 210 may have various structures depending on the method of driving the liquid crystal layer.

Although not shown, a gate driving printed circuit board (PCB) for supplying a scan signal to a gate line is provided at an edge of the display panel 210, a data driving printed circuit board (PCB) May be provided. On the other hand, a polarizing film (not shown) may be disposed on at least one of the upper side and the lower side of the display panel 210.

The optical sheet 220 may be disposed between the display panel 210 and the backlight unit 100, and the optical sheet 220 may be removed, but the present invention is not limited thereto. The optical sheet 220 may include a diffusion sheet (not shown) and / or a prism sheet (not shown).

The diffusing sheet diffuses the light emitted from the light guide plate evenly, and the diffused light can be converged on the display panel by the prism sheet. Here, the prism sheet may be selectively formed using a horizontal or vertical prism sheet, one or more roughness enhancing films, or the like. The types and the number of the optical sheets 220 can be added or deleted within the technical scope of the embodiments, but the invention is not limited thereto.

On the other hand, the backlight unit 100 may include a plurality of optical assemblies, and the plurality of optical assemblies may include a light source 13 and a light guide plate 15, respectively.

The light source 13 is located on the side surface of the optical plate 15 and the light emitted from the light source 13 can be incident on the side surface of the light guide plate 15. For example, the light source 13 may be configured using a light emitting diode (LED), and may include a plurality of light emitting diodes (LEDs).

The light emitting diode may be a side emitting type and may be a colored LED emitting at least one color from colors such as red, blue, green, etc., or a white LED. Also, the colored LED may include at least one of a red LED, a blue LED, and a green LED, and the arrangement and emission light of such a light emitting diode may be changed within the technical scope of the embodiment.

The light guide plate 15 is made of a transparent material and includes one of acrylic resin type such as PMMA (polymethyl methacrylate), polyethylene terephthlate (PET), polycarbonate (PC), and polyethylene naphthalate can do. The light guide plate 15 may be formed by an extrusion molding method.

The light guide plate 15 may refract and scatter light incident from the light source 13 to emit light toward the upper side, that is, toward the display panel 210. Further, a reflection member (not shown) may be formed on the lower side of the light guide plate 15.

The light source 13 and the light guide plate 15 shown in FIG. 1 are mainly shown with respect to their respective functions. The shape, the coupling structure or the positional relationship of the light source 13 and the light guide plate 15 can be changed Do.

For example, the two light guide plates 15 adjacent to each other may partially overlap each other, and the light guide plate 15 may have a shape in which the thickness gradually decreases in one direction.

The display panel 210 may have a plurality of divided regions corresponding to the plurality of light guide plates 15. The display panel 210 may display the brightness of light emitted from the light guide plate of the corresponding optical assembly according to the gray peak value or the color coordinate signal of the divided region, That is, the brightness of the light source is adjusted, so that the brightness of the display panel 210 can be adjusted.

3 is a plan view of a first embodiment of the configuration of the backlight unit 100, and is a simplified view of the configuration of the backlight unit 100 viewed from the front.

Referring to FIG. 3, a plurality of optical assemblies 10 provided in the backlight unit 100 are arranged in matrix form in N and M (N and M are natural numbers of 1 or more) in the x-axis and y-axis directions, respectively And each optical assembly 10 may include a light source 13 and a light guide plate 15.

The light source 13 may be arranged adjacent to the lower end of the light guide plate 15 and the light emitted from the light source 13 may be incident on the lower end of the light guide plate 15 at a side thereof, It can proceed in a parallel direction.

Each optical assembly 10 is driven in an edge-type backlight manner, and each optical assembly 10 again acts as a light source so that a plurality of optical assemblies 10 are arranged in a direct-backlight manner to form a backlight unit can do. Accordingly, it is possible to solve the problem that the light emitting diodes are observed as hot spots on the screen, reduce the thickness of the light guide plate, and reduce the number of optical films, thereby realizing slimming of the backlight unit.

For example, as shown in FIG. 3, the backlight unit 100 may have nine optical assemblies (M1 to M9) arranged in a 3x3 array. However, since the configuration shown in FIG. 3 is only an example for describing the backlight unit according to the present invention, the present invention is not limited thereto and can be changed according to the screen size and the like of the display device.

Each optical assembly 10 may be fabricated as an independent assembly and may be closely spaced to form a modular backlight unit. Such a modular backlight unit can provide light to the display panel 210 as backlight means.

The backlight unit 100 may be driven by a whole driving method or a partial driving method such as local dimming, impulsive or the like. The driving method of the light emitting diode may be variously changed according to the circuit design, but is not limited thereto. Thus, in the embodiment, the color contrast ratio is increased and the image of the bright part and the dark part on the screen can be expressed clearly, thereby improving the image quality.

That is, the backlight unit 100 is divided into a plurality of divided driving regions corresponding to the plurality of light guide plates 15, and the luminance of the divided driving region is associated with the luminance of the video signal, And the bright portion increases the brightness, thereby improving the contrast ratio and sharpness.

For example, only some of the optical assemblies 10 of M1 to M9 shown in FIG. 3 may be independently driven to emit light upwardly, and the light sources (not shown) included in each of the optical assemblies 10 13 can be independently controlled.

On the other hand, the area of the display panel 210 corresponding to one optical assembly 10 or one light guide plate 15 can be divided into two or more blocks, and the display panel 210 and the backlight unit can be divided into blocks Can be driven.

As shown in Fig. 3, the optical assemblies 10 adjacent to each other can be arranged with a constant distance d1, d2. For example, the two light guide plates 15 adjacent to each other in the x direction, that is, the lateral direction, may be disposed with a distance d1, and the two light guide plates 15 adjacent to each other in the y direction, that is, the longitudinal direction, have.

On the other hand, at the boundaries between the optical assemblies 10, more specifically, between the adjacent light guide plates 15 by the above-mentioned intervals d1 and d2, A bright line or a dark line may appear in the region 60 corresponding to the portion.

That is, as the distances d1 and d2 between the adjacent light guide plates 15 become narrower, the amount of light emitted to the front face through the boundary portion increases, and the area 60 corresponding to the boundary portion between the light guide plates 15 As the luminance of the light increases, a bright line may appear, and thus a bright line may be visually displayed on the display screen.

That is, as the distance d1, d2 between the light guide plates 15 adjacent to each other is widened, the amount of light emitted to the front face through the boundary portion decreases, and the area 60 corresponding to the boundary portion between the light guide plates 15 As the luminance of the light becomes lower, a dark line may appear.

Therefore, according to the embodiment of the present invention, the image quality of the display image can be improved by adjusting the intervals d1 and d2 between the adjacent light guide plates 15 to a numerical range in which no bright line or dark line appears at the boundary portion.

Table 1 below shows the results of experiments on the occurrence of a bright line or a dark line according to the distance d1 between the adjacent light guide plates 15. The interval d1 is the horizontal direction x, ) Between the two adjacent light guide plates 15 in a direction perpendicular to the direction in which light is emitted from the light guide plate 15.

In the meantime, the following experimental results were obtained by examining whether a visual or luminous line or a dark line was perceived by varying the intervals d1 and d2 between the adjacent light guide plates 15 for a plurality of experimenters, and 90% When the above-mentioned experimenters perceive a bright line or a dark line, it is shown that a bright line or a dark line is generated.

Referring to Table 1, when the distance d1 between the two light guide plates 15 adjacent to each other in the direction perpendicular to the direction in which light is emitted from the light source 13, that is, in the lateral direction (x) is less than 0.3 mm, A bright line may appear on the display screen. If the interval d1 exceeds 2.5 mm, the brightness of the light decreases at the boundary portion, and a dark line may appear on the display screen.

Therefore, in order to prevent the image quality of the image from deteriorating due to a bright line or a dark line appearing on the display screen, it is preferable that the distance between the two light guide plates 15 adjacent in the direction perpendicular to the direction in which the light is emitted from the light source 13, Is preferably in the range of 0.3 mm to 2.5 mm.

3, the light emitted from the light source 13 is incident on the lower end portion of the light guide plate 15 and progresses to the upper end portion. Thus, the light guide plate 15 is disposed on the lower portion 120 adjacent to the light source 13, May be larger than the amount of light emitted upward from the upper portion 130 remote from the light source 13. [ The brightness of the display screen portion corresponding to the lower end portion 120 of the light guide plate 15 may be higher than that of the display screen portion corresponding to the upper end portion 130 of the light guide plate 15. [

The distance d2 between the two light guide plates 15 adjacent to each other in the direction parallel to the direction in which the light is emitted from the light source 13, that is, in the vertical direction y, The display panel 130 can be compensated for by using the high luminance of the lower end portion 120 of the light guide plate 15 and the overall luminance uniformity of the display screen can be maintained.

For example, the distance d2 between the two light guide plates 15 adjacent in the direction parallel to the direction in which the light is emitted from the light source 13, i.e., in the longitudinal direction y, It is desirable to set it to be smaller.

Table 2 below shows the results of experiments on the occurrence of bright lines or dark lines according to the interval d2 between the adjacent light guide plates 15. The interval d2 is the vertical direction y, And the distance between two adjacent light guide plates 15 in a horizontal direction.

Referring to Table 2, when the distance d2 between the two light guide plates 15 adjacent to each other in the horizontal direction, that is, in the vertical direction (y) is less than 0.3 mm, the luminance of light at the boundary portion A bright line may appear on the display screen. If the interval d2 exceeds 1.5 mm, the brightness of the light decreases at the boundary portion, and a dark line may appear on the display screen.

As described above, as the luminance of the lower light guide plate upper part 130 of the two light guide plates 15 adjacent to each other in the vertical direction (y) is low, the interval (d) in the vertical direction (y) it can be seen that a dark line is generated in a range exceeding 1.5 mm, which is smaller than the range in which the dark line is generated in (d1).

Therefore, in order to prevent the bright line or the dark line from appearing on the display screen and ensure the uniformity of brightness of the display screen, And the distance d2 between the protrusions 15 is preferably in the range of 0.3 mm to 1.5 mm.

3 and 4, the embodiment of the present invention has been described by taking the case where the light source 13 is positioned below the light guide plate 15 as viewed from the front, but the present invention is not limited thereto That is, the light source 13 may be arranged on the upper side, the left side, or the right side of the light guide plate 15.

FIG. 5 is a schematic plan view of a diffusion sheet provided in a backlight unit according to an embodiment of the present invention. FIG. 5 is a simplified plan view of the diffusion sheet.

The diffusion sheet 221 is disposed on the upper side of the light guide plate 15 and can diffuse light emitted from the light guide plate 15 to uniformize the brightness of light provided to the display panel 210.

5, a pattern 222 may be formed on the diffusion sheet 221. The pattern 222 may be formed on the boundary portion d1 or d2 between the adjacent light guide plates 15 as described with reference to FIG. And at least a part of them overlap with each other.

At least some of the patterns 222 formed on the diffusion sheet 221 may be overlapped with the portions 60 where the bright lines or dark lines appear as described with reference to Fig.

The pattern 222 may be formed on the lower side or the upper side of the diffusion sheet 221 and may protrude downward, that is, toward the light guide plate 15 or upwardly, And may include a plurality of protrusions (not shown).

As described above, the plurality of protrusions respectively diffuse or condense the light emitted from the backlight unit 100, and more specifically, the boundary portion which is the space between the adjacent light guide plates 15, to form the light guide plate 15 The occurrence of a bright line or a dark line in the region 60 corresponding to the boundary portion between the pixels can be reduced.

That is, the pattern 222 formed on the diffusion sheet 221 can diffuse the light emitted from the boundary portion between the adjacent light guide plates 15, thereby reducing the phenomenon that light is concentrated at the boundary portion and a bright line appears.

As another embodiment of the present invention, the pattern 222 formed on the diffusion sheet 221 condenses the light emitted from the boundary portion between the adjacent light guide plates 15 to reduce the appearance of dark lines in the boundary portion .

The pattern 222 formed on the diffusion sheet 221 is irradiated with light from the first pattern portion 222a and the light source 13 extending in the direction in which light is emitted from the light source 13, And a second pattern portion 222b extending in a direction intersecting with the direction in which the light is emitted, for example, in the lateral direction (x).

5, the first pattern portion 222a and the second pattern portion 222b may be formed in directions intersecting with each other.

The width w1 of the first pattern portion 222a extending in the direction in which the light is emitted from the light source 13 may be larger than the width w2 of the second pattern portion 222b formed in the direction intersecting therewith .

That is, the widths w1 and w2 of the first and second pattern units 222a and 222b are proportional to the width of the overlapping portion of the light guide plate 15, that is, the distances d1 and d2 between the light guide plates 15 The width w1 of the first pattern portion 222a may be greater than the width w2 of the second pattern portion 222b as d1 is set larger than d2 as described above with reference to FIG.

Hereinafter, the shape of the diffusion sheet 221 provided in the backlight unit according to the embodiment of the present invention will be described in detail with reference to FIG. 6 to FIG.

6, a plurality of protrusions 223 may be formed on a lower surface of the diffusion sheet 221, that is, a surface adjacent to the light guide plate 15 on both surfaces of the diffusion sheet 221, and the protrusions 223 May protrude downward, that is, toward the light guide plate 15.

6, a part of the pattern 222 including the plurality of protrusions 223 overlaps the boundary portion 70 which is a space between two adjacent light guide plates 151 and 152, May not overlap the boundary portion (70) between the light guide plates (151, 152).

The light guide plate 15 and more specifically the boundary portion 70 between the two adjacent light guide plates 151 and 152 and the peripheral portion 70 adjacent to the boundary portion by the plurality of protrusions 223 formed on the lower side of the diffusion sheet 221, The light emitted upward can be diffused, thereby preventing a bright line from appearing.

As shown in Fig. 6, the diffusing sheet 221 is provided so as to correspond to the region where the luminance is uneven, that is, the boundary portion 70 between the light guide plates 151 and 152 and the region adjacent thereto, By forming the pattern 222, uniformity of light provided to the display panel 210 can be ensured without increasing the thickness of the diffusion sheet 221. [

The shape, size or number of protrusions 223 shown in FIG. 6 is for illustrating an embodiment according to the present invention, and the present invention is not limited thereto.

Figs. 7A and 7B are perspective views showing embodiments of the structure of the diffusion sheet 221 having the sectional configuration shown in Fig.

Referring to FIG. 7A, a plurality of protrusions 223 having a prism shape, that is, a triangular prism shape, may be formed on one surface of the diffusion sheet 221. 7A, the light emitted from the boundary portion 70 between the light guide plates 151 and 152 and the region adjacent thereto is diffused to remove the bright line, can do.

Referring to FIG. 7B, the plurality of protrusions 223 formed on one surface of the diffusion sheet 221 may each have a polygonal pyramid shape, for example, a pyramid shape.

8 illustrates a cross-sectional configuration of a backlight unit according to a second embodiment of the present invention. The description of the same components as those described with reference to Figs. 1 to 7 of the configuration of the backlight unit shown in Fig. .

Referring to FIG. 8, the pattern 222 formed on the lower surface of the diffusion sheet 221 may include a plurality of protrusions 223 having a cross-sectional shape similar to a semicircle.

As described above, by the plurality of protruding portions 223, the boundary portion 70 between the light guide plate 15, more specifically, the adjacent two light guide plates 151 and 152, and the peripheral portion adjacent to the boundary portion are emitted upward Light can be diffused, and a bright line can be prevented from appearing.

Figs. 9A and 9B are perspective views showing embodiments of the structure of the diffusion sheet 221 having the sectional configuration shown in Fig.

Referring to FIG. 9A, a plurality of protrusions 223 having a semicircular column, that is, a lenticular shape, may be formed on one surface of the diffusion sheet 221. 9A, the light emitted from the boundary portion 70 between the light guide plates 151 and 152 and the region adjacent thereto is diffused to remove the bright line, can do.

9B, the plurality of protrusions 223 formed on one surface of the diffusion sheet 221 may each have a hemispherical shape and may be, for example, a micro lens having a diffusion function .

According to the embodiment of the present invention, the plurality of pattern units 223 included in the pattern 222 of the diffusion sheet 221 may differ in density, size, or shape depending on the position.

Referring to FIG. 10, the density of the protrusions 223 may decrease as the pattern 222 of the diffusion sheet 221 goes from the center to the periphery of the boundary portion 70 between the light guide plates 151 and 152.

That is, in the pattern 222, the density of the projections 223 is high at the central portion overlapping the boundary portion 70 between the light guide plates 151 and 152, and at the outer portion that is not overlapped with the boundary portion 70, The density of the grooves 223 may be lower than that of the center portion.

As described above, by changing the density of the protrusions 223 included in the pattern 222 according to the position, the uniformity of the brightness can be more easily ensured.

That is, since the bright line appearing near the boundary portion 70 between the light guide plates 151 and 152 has the highest luminance at the center portion and lower luminance toward the outer portion, By increasing the density of the protrusions 223 included in the outer portion to be higher than the density of the protrusions 223 of the outer portion, it is possible to further increase the diffusion effect on the center portion, thereby effectively removing the bright line.

Referring to FIG. 11, the size of the protrusion 223 of the pattern 222 of the diffusion sheet 221 may be reduced toward the outer periphery from the center of the boundary portion 70 between the light guide plates 151 and 152.

That is, in the pattern 222, the protrusion 223 is large in the central portion overlapping the boundary portion 70 between the light guide plates 151 and 152, and in the outer portion that is not overlapped with the boundary portion 70, 223 may be smaller than the center portion.

The diffusion effect on the central portion can be further increased by making the protrusion 223 included in the center portion of the pattern 222 larger than the protrusion 223 of the outer portion as shown in FIG. It can be removed more effectively.

12, the pattern 222 of the diffusion sheet 221 may have an increased bottom width of the protruding portion 223 from the center to the outer periphery, which overlaps the boundary portion 70 between the light guide plates 151 and 152 .

That is, in the pattern 222, the bottom surface width of the protruding portion 223 is large at the central portion overlapping the boundary portion 70 between the light guide plates 151 and 152, and at the outer peripheral portion that is not overlapped with the boundary portion 70, The width of the bottom surface of the base portion 223 may be larger than that of the center portion.

As shown in FIG. 12, by making the bottom width of the protrusion 223 included in the central portion of the pattern 222 smaller than the bottom width of the protrusion 223 of the outer portion, the diffusion effect on the center portion can be further increased And thus, the bright line can be removed more effectively.

As another embodiment of the present invention, a plurality of protrusions 223 may be formed on the upper surface of the diffusion sheet 221, that is, on the surface of the diffusion sheet 221, which is far from the light guide plate 15 And the protrusions 223 may protrude upward, that is, in the direction of the display panel 210.

FIG. 13 illustrates a cross-sectional structure of a diffusion sheet according to another embodiment of the present invention, and a description of the same structure as that described with reference to FIGS. 1 to 12 of the structure shown in FIG. 13 will be omitted below.

13, a plurality of protrusions 223 formed on the upper surface of the diffusion sheet 221 form a boundary portion 70 between the light guide plate 15, more specifically, two adjacent light guide plates 151 and 152, The light emitted upward from the peripheral portion adjacent to the boundary portion 70 can be condensed so that the dark line can be prevented from appearing near the boundary portion 70.

13, the shape of the pattern 222 projected on the upper surface of the diffusion sheet 221 and the like may be similar to those described with reference to Figs. 6 to 12. Fig.

Referring to FIG. 14, a plurality of protrusions 223 may be formed on the upper surface and the lower surface of the diffusion sheet 221, respectively.

That is, the protrusions 223 formed on the upper surface of the diffusion sheet 221 condense the light incident from the lower side, and the protrusions 223 formed on the lower surface of the diffusion sheet 221 spread the light incident from the lower side. .

The light emitted from the boundary portion 70 between the light guide plates 151 and 152 is diffused (diffused) when the region overlapping the boundary portion 70 between the light guide plates 151 and 152 is higher in brightness than the surrounding region. And the light emitted from the peripheral portion of the boundary portion 70 is condensed to ensure the uniformity of the light luminance at the boundary portion 70 between the light guide plates 151 and 152 and the periphery thereof.

15 is a cross-sectional view illustrating a configuration of a backlight unit according to an embodiment of the present invention. The description of the same components as those described with reference to Figs. 1 to 14 of the backlight unit shown in Fig. 15 will be omitted do.

15, the optical assembly 10 includes a light source 13, a light guide plate 15, a reflecting member 17, and a side cover 20 for fixing the light source 13 and the light guide plate 15 . Meanwhile, the side cover 20 provides a fixing position for the bottom cover 110, and may include a first side cover 21 and a second side cover 22.

The light guide plate 15 may be composed of a first part 15b and a second part 15a and the second part 15a may be composed of an upper surface on which the surface light source is generated and a lower surface opposed to the upper surface, .

The first part 15b may protrude horizontally along the lower side of one of the side surfaces of the second part 15a. Here, the first part 15b is a light-incident part through which the light is incident from the light source 13, and the second part 15a emits the light incident on the side through the light- As shown in Fig.

According to an embodiment of the present invention, optical assemblies 10 adjacent to each other, more specifically, two light guide plates 15 adjacent to each other may be arranged so that predetermined regions overlap each other.

For example, a light source 13, a first part 15b, that is, a light entrance part and a side cover 20 are disposed on one side of the optical assembly 10, and the light source 13, The first part 15b and the side cover 20 are disposed adjacent to the optical assembly 10 and more specifically the second part 15a of the light guide plate 15 provided in the optical assembly, .

The plurality of optical assemblies 10 are partially overlapped as described above, so that the light source 13, the first part 15b, and the side cover 20 are not observed from the front surface.

As described above, since the adjacent optical assemblies 10 included in the backlight unit 100 are arranged so as to overlap with each other, it is possible to improve the bright line or dark line generation at the boundary of the optical assemblies 10 and to secure uniformity of light .

15, when the predetermined areas of the two light guide plates 15 adjacent to each other are overlapped with each other, the gap between the two light guide plates 15 is set such that the distance between the light guide plate 15 and the light guide plate 15 Can be defined as intervals.

That is, the interval may be the interval between the second parts 15a, which are light emitting parts of the two light guide plates 15 adjacent to each other.

It is preferable that the interval is a distance between two light guide plates 15 adjacent to each other in a direction parallel to a direction in which light is emitted from the light source 13 and has a range of 0.3 mm to 1.5 mm as described above.

15, the two light guide plates 15 adjacent to each other in the direction perpendicular to the direction in which the light is emitted from the light source 13, that is, in the x direction, do not overlap with each other, The interval between the two light guide plates 15 may have the same range as d1 described with reference to Figs.

15, a pattern 222 including a plurality of projections 223 overlapping a space between two adjacent light guide plates 15, that is, a boundary portion, 221 on the lower or upper surface.

On the other hand, a scattering pattern (not shown) may be formed on the upper surface or the lower surface of the light guide plate 15, and the scattering pattern may have a predetermined pattern to diffuse the incident light to improve the light uniformity on the entire surface of the light guide plate 15 It plays a role.

On the other hand, the second part 15a of the light guide plate 15, that is, the lower surface of the light emitting part is formed to be inclined at a predetermined angle, and the thickness of the second part 15a may gradually decrease toward the opposite side from the part adjacent to the first part 15b.

The light guide plate 15 may be provided with a reflective member 17 and the reflective member 17 is guided inside the light guide plate 15 by the light incident on the side through the first part 15b, So that it can be emitted to the upper side. In addition, the reflective member 17 may interfere with interference caused by the light generated in the other optical assemblies 10 arranged in a superimposed manner.

16 is a perspective view of an embodiment of a shape of a light guide plate included in the backlight unit.

15 and 16, the light guide plate 15, more specifically, the first part 15b of the light guide plate 15 may include a protrusion 30 protruding at a predetermined height (a). The protrusions 30 may be formed in at least two places in the x-axis direction on the upper surface of the first part 15b of the light guide plate 15. [

The protrusion 30 may have various shapes, for example, a shape similar to a rectangular parallelepiped. The projections 30 are engaged with the first side cover 21 to prevent shaking of the light guide plate 15 in the x- and y-axes.

A part 30a of the projection 30 may be formed in a round shape to prevent a crack from being generated in the projection due to the impact applied to the projection 30 by the movement of the light guide plate 15. [

Meanwhile, the protrusion 30 may have a height a of 0.3 to 0.6 mm from the upper surface of the first part 15b. The width b of the projection 30 in the x axis may be 2 to 5 mm. The width c of the projection 30 in the y-axis may be 1 to 3 mm.

The protrusions 30 may be disposed between adjacent light emitting diodes 11 and may be formed in the vicinity of the light incidence surface 16 on the upper surface of the first part 15b so that light generated in the light emitting diodes 11 It is possible to prevent optical interference from being generated due to the protrusion 30 formed integrally with the light guide plate 15.

The light source 13 may include a module substrate 12 on which at least one light emitting diode 11 and a light emitting diode 11 are mounted. The light emitting diodes 11 may be arranged in the x-axis direction on the module substrate 12 and disposed close to the light incidence surface 16 of the first part 15b.

The module substrate 12 is made of a metal core PCB, an FR-4 PCB, a general PCB, a flexible substrate, and the like, and can be variously modified within the technical scope of the embodiment. A thermal pad (not shown) may be disposed under the module substrate 12. The heat dissipating member may be formed between the module substrate 12 and the second side cover 22.

The light generated in the light emitting diode 11 is incident on the first part 15b. The light incident from the light emitting diodes 11 may be mixed in the light guide plate 15 including the first part 15b.

Light incident from the light emitting diodes 11 is guided in the first part 15b and incident on the second part 15a. The light incident on the second part 15a is reflected by the reflecting member 17 on the lower surface and is emitted to the upper surface. At this time, light is scattered and diffused by the scattering pattern formed on the lower surface of the light guide plate 15, so that the light uniformity can be improved.

The light emitting diodes 11 may be arranged on the module substrate 12 at predetermined intervals. The light emitting diodes 11 may be arranged diagonally with respect to the projections 30 in order to minimize the optical effect of the protrusions 30 formed on the light guide plate 15. [ The spacing of the light emitting diodes 11 around the projections 30 may be wider than the spacing of the other light emitting diodes 11. [

A space for coupling the first side cover 21 and the second side cover 22 is ensured and the light emitting diodes 11 are arranged in order to minimize the optical influence that may be caused by the pressing of the light guide plate 15 by the coupling force. The distance between some of the light emitting diodes 11 may be wider than the distance between the other light emitting diodes 11.

For example, if the first spacing d of the adjacent light emitting diodes 11 is about 10 mm, the second spacing e of the light emitting diodes 11 near the location where the space for the coupling is provided may be about 13 mm .

The light generated by the light emitting diodes 11 may be mixed in the light guide plate 15 including the first part 15b and uniformly supplied to the second part 15a.

A side cover 20 is formed to surround a part of the light source 13 and the light guide plate 15 and the side cover 20 is disposed on the light source 13 and the first part 15b of the light guide plate 15 And a second side cover 22 disposed below the first part 15b. The side cover 20 may be made of plastic or metal.

The second side cover 22 is formed to face the lower surface of the first part 15b. The second side cover 22 may be formed by being bent in the upper direction (z-axis line) so as to face the light incidence surface 16 at the lower surface of the first part 15b. A part 22a of the second side cover 22 may be inclined along the lower surface of the light guide plate 15 or a part of the inclined surface and the light source 13 may be accommodated in the second side cover 22. [

The first side cover 21 and the second side cover 22 are fastened to each other by the first fixing member 51 so that the light source 13 and the light guide plate 15 are not shaken by an external impact, So that shaking can be prevented.

The second side cover 22 can support the inclined surface of the light guide plate 15 to firmly maintain alignment of the light guide plate 15 and the light source 13 and protect the light guide plate 15 and the light source 13 from external impacts.

The first side cover 21 may have a first hole 41 at a position corresponding to the projection 30 of the first part 15b.

The first hole 41 may be larger than the projection 30 so that the projection 30 is engaged with the projection 30. The circumference of the first hole 41 may be spaced a predetermined distance from a part of the edge of the protrusion 30. The space may be formed in the light guide plate 15 when the light guide plate 15 expands due to a change in external environment, And may be a margin for preventing the deformation of the base 15. At this time, another portion of the projection 30 may contact the periphery of the first hole to enhance the fixing force.

At least one second hole (42) may be further formed in the first side cover (21). At least one third hole 43 may be formed in the second side cover 21 at a position corresponding to the second hole 42.

The backlight unit 100 having the above-described structure may be housed in a box-shaped bottom cover having an opened upper side.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications other than those described above are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

1 is an exploded perspective view showing a configuration of a display device according to an embodiment of the present invention.

2 is a cross-sectional view showing an embodiment of a display module configuration.

3 is a plan view schematically showing the configuration of the backlight unit.

4 is a diagram showing a dark line or a bright line on the display screen.

5 is a plan view briefly showing a structure of a diffusion sheet provided in a backlight unit according to an embodiment of the present invention.

6 is a cross-sectional view showing a sectional configuration of a backlight unit according to the first embodiment of the present invention.

7A and 7B are perspective views showing embodiments of the structure of the diffusion sheet having the sectional configuration shown in FIG.

8 is a cross-sectional view showing a cross-sectional structure of a backlight unit according to a second embodiment of the present invention.

9A and 9B are perspective views showing embodiments of the structure of the diffusion sheet having the sectional configuration shown in FIG.

10 to 14 are sectional views showing still another embodiment of the structure of the diffusion sheet.

15 is a cross-sectional view showing a cross-sectional structure of a backlight unit according to an embodiment of the present invention.

16 is a perspective view showing an embodiment of the shape of the light guide plate.

Claims (16)

A light source for emitting light; A plurality of light guide plates for upwardly emitting light incident on the light source side; And And a diffusion sheet disposed on the light guide plate and having a pattern protruding in a predetermined direction, At least a part of the pattern formed on the diffusion sheet overlaps a boundary portion between adjacent light guide plates, Wherein an interval between the light guide plates adjacent to each other in the direction perpendicular to the direction in which the light is emitted is larger than a distance between the light guide plate adjacent in the horizontal direction and a direction in which the light is emitted, The pattern formed on the diffusion sheet may be formed, A first pattern portion formed in a region corresponding to a boundary between the adjacent light guide plates in the vertical direction and a second pattern portion formed in a region corresponding to a boundary between the adjacent light guide plates in the horizontal direction, The width of the first pattern portion may be, A width of the second pattern portion Backlight unit. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet And a plurality of protrusions formed on a lower surface of the diffusion sheet and protruding toward the light guide plate. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet And a plurality of protrusions formed on an upper surface of the diffusion sheet and protruding in a direction opposite to the direction of the light guide plate. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet A first protrusion formed on an upper surface of the diffusion sheet and a second protrusion formed on a lower surface of the diffusion sheet. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet And a plurality of protrusions having a shape of any one of a prism, a semicircular pillar, a hemisphere, and a polygonal pyramid. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet Wherein the density of the protrusions decreases as the distance from the center to the outer periphery overlaps the boundary between the light guide plates. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet Wherein a size of the protrusions decreases from a center to an outer periphery overlapping the boundary between the light guide plates. The method as claimed in claim 1, wherein the pattern formed on the diffusion sheet And a bottom surface of the protrusions increases in width from a center to an outer periphery overlapping the boundary between the light guide plates. delete delete The method according to claim 1, And a side cover to which the light source and the light guide plate are fixed. delete delete delete A display device comprising the backlight unit according to claim 1. A backlight unit according to claim 1; And And a display panel positioned above the backlight unit and displaying an image using light emitted from the backlight unit, Wherein the display panel is divided into a plurality of regions and a brightness of light emitted from a light guide plate corresponding to the region is adjusted according to a gray level peak value or a color coordinate signal of each of the plurality of regions.

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