TWI724650B - Backlight unit and display device - Google Patents

Abstract

In an embodiment, a display device comprises a display panel and a backlight unit. The backlight unit comprises a printed circuit, a light-emitting device on the printed circuit, and a transparent film including a holographic film. The holographic film includes at least one optical pattern overlapping the light-emitting device and modifying an angle of a portion of light emitted by the light-emitting device. The backlight unit further comprises a light output pattern, where the portion of light with the modified angle passes through the light output pattern toward the display panel. The light output pattern may have a refractive index greater than a refractive index of the transparent film such that a refraction angle of the portion of light exiting the light output pattern is less than an incidence angle of the portion of light entering the light output pattern.

Description

Backlight unit and display device

Embodiments of the present invention relate to a backlight unit and a display device.

With the development of information-oriented society, the demand for display devices that display images has increased, and various types of display devices such as liquid crystal display devices and organic light-emitting display devices have been widely used.

The liquid crystal display device among these display devices includes a display panel and a light source device that supplies light to the display panel, such as a backlight unit.

Therefore, the thickness of the display device may increase due to the backlight unit. When the thickness of the backlight unit is reduced, there will be a problem that a sufficient optical gap cannot be ensured between the light source and the display panel, and the image quality will be reduced accordingly.

In various embodiments, a display device includes a display panel; and a backlight unit. The backlight unit includes: a printed circuit; a light emitting device located on the printed circuit; and a transparent film including a holographic film on the bottom surface of the transparent film facing the printed circuit. The holographic film includes at least one optical pattern that overlaps the light-emitting device and changes the angle of a part of the light emitted by the light-emitting device. The backlight unit further includes a light output pattern on the upper surface of the transparent film, and the portion of the light having a changed angle passes through the light output pattern toward the display panel. The refractive index of the light output pattern is greater than the refractive index of the transparent film, so that the refraction angle of the light leaving the portion of the light output pattern is smaller than the incident angle of the light entering the portion of the light output pattern.

In one embodiment, the display device further includes a coating on the transparent film, and the refractive index of the coating is lower than the refractive index of the transparent film.

In one embodiment, the optical pattern changes the angle of another part of the light emitted by the light-emitting device, and the coating reflects the other part of the light having the changed angle toward the bottom surface of the transparent film.

In one embodiment, the coating overlaps the light output pattern.

In an embodiment, light passing through the portion of the light output pattern with a changed angle further passes through the coating.

In one embodiment, the upper surface of the coating is flat.

In one embodiment, the holographic film further includes a base film between the bottom surface of the transparent film and the optical pattern, and the refractive index of the base film is lower than the refractive index of the optical pattern.

In one embodiment, the at least one optical pattern is arranged on the bottom surface of the base film in a lattice shape.

In one embodiment, the refractive index of the base film is equal to or lower than the refractive index of the transparent film.

In one embodiment, the optical pattern is a diffraction pattern, and the refractive index of the optical pattern is greater than the refractive index of the transparent film.

In one embodiment, the light output pattern has an elliptical shape. The semi-major axis of the elliptical shape may be equal to the semi-minor axis of the elliptical shape. In another embodiment, the semi-major axis of the elliptical shape is larger than the semi-minor axis of the elliptical shape.

In an embodiment, the upper surface of the light output pattern is parallel to the lower surface of the light output pattern. The light output pattern may have a trapezoidal shape.

In one embodiment, the display device further includes: a bottom cover under the printed circuit; and an adhesive tape for bonding the printed circuit to the bottom cover.

In one embodiment, the holographic film includes: a first plurality of optical patterns located in an area overlapping with the light-emitting device; and a second plurality of optical patterns located in another space overlapping with the plurality of light-emitting devices In a region, the density of the first plurality of optical patterns is greater than the density of the second plurality of optical patterns.

In one embodiment, the display device further includes a reflective film that accommodates and exposes the light-emitting device, the reflective film has a height greater than that of the light-emitting device and is configured to reflect light emitted from the light-emitting device.

In various embodiments, a backlight unit includes: a printed circuit; a light emitting device on the printed circuit; and a transparent film included on the bottom surface of the transparent film facing the printed circuit An optical pattern on the upper side, the optical pattern overlaps the light-emitting device and changes the angle of a part of the light emitted by the light-emitting device. The backlight unit further includes: a diffusion film on the transparent film; and a light output pattern on the upper surface of the transparent film and under the diffusion film. The portion of the light having the changed angle passes through the light output pattern toward the diffusion film, and the refractive index of the light output pattern is greater than the refractive index of the transparent film, so that the refraction angle of the light leaving the portion of the light output pattern is less than The angle of incidence of light entering the portion of the light output pattern.

In an embodiment, the backlight unit further includes a coating between the transparent film and the diffusion film, and the refractive index of the coating is lower than the refractive index of the transparent film.

In an embodiment, the backlight unit further includes: a color conversion sheet on the diffusion film; and more than one optical sheet on the color conversion sheet.

In various embodiments, a backlight unit includes a plurality of light sources arranged on a printed circuit. The backlight unit further includes a reflective film arranged in at least one area different from another area on the printed circuit where the plurality of light sources are arranged. The backlight unit also includes a light source protection part arranged on the plurality of light sources and the reflective film. The backlight unit further includes a transparent film arranged on the light source protection part. The backlight unit further includes a plurality of light modification patterns arranged at positions corresponding to the plurality of light sources on the bottom surface of the transparent film, wherein there is an air gap between the plurality of light modification patterns and the light source protection part.

In an embodiment, the thickness of the central portion in at least one of the plurality of light modification patterns is greater than the thickness of the peripheral portion thereof.

In an embodiment, the plurality of light modification patterns include: a first light modification pattern arranged in a peripheral area of a display panel; and a second light modification pattern arranged in a central area of the display panel , And wherein the thickness of the first light modification pattern is smaller than the thickness of the second light modification pattern, or the area of the first light modification pattern is smaller than the area of the second light modification pattern.

In an embodiment, the backlight unit further includes an adhesive layer disposed between the light source protection part and the transparent film, and wherein the adhesive layer is disposed on the other side of the light-modified pattern. In at least one area with different areas, and the edge of each of the plurality of light modification patterns is separated from the adhesive layer.

100: display device

110: display panel

120: Gate drive circuit

130: data drive circuit

140: Controller

201: bottom cover

202: Printed Circuit

203: light source

203a: Light-emitting part

203b: Electrode part

204: reflective film

205: Light source protection part

206: Diffusion film

207: Color conversion film

208: optical sheet

209: Adhesive layer

210: Tape

300: transparent film

310: Optical pattern

311: Light Modification Pattern

311a, 311b, 311c, 311d, 311e, 311f, 311g: light modification pattern

312: Diffraction pattern

320: light output pattern

330: basement membrane

340: Coating

400: Boot panel

500: foam pad

A/A: Active area

Area1: the first area

Area2: The second area

D1, D2, D3, D4: clearance

DATA: image data

DCS: data control signal

DL: Data line

GCS: Gate control signal

GL: Gate line

N/A: Inactive area

S1, S2: size

SP: sub pixel

T1, T2: thickness

W1, W2: area

θ1, θ2: angle

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

FIG. 2 is a schematic diagram showing an example of the structure of a backlight unit included in a display device according to an embodiment of the present invention.

3A to 3E are schematic diagrams showing examples of the backlight unit shown in FIG. 2.

FIG. 4 is a schematic diagram showing an embodiment of the structure of the backlight unit according to the embodiment of the present invention.

5A and 5B are schematic diagrams showing an example of the structure through the position of the light modification pattern included in the backlight unit shown in FIG. 4.

FIG. 6 is a schematic diagram showing an embodiment of the structure of the backlight unit according to the embodiment of the present invention.

FIG. 7 is a schematic diagram showing an example of the structure of a transparent film in which a diffraction pattern and a light output pattern are arranged, and the transparent film is included in the backlight unit shown in FIG. 6.

FIG. 8 is a schematic diagram showing another example of the structure of a transparent film in which a diffraction pattern and a light output pattern are arranged, and the transparent film is included in the backlight unit shown in FIG. 6.

FIG. 9 is a schematic diagram showing still another example of the structure of a transparent film in which a diffraction pattern and a light output pattern are arranged, and the transparent film is included in the backlight unit shown in FIG. 6.

FIG. 10 is a schematic diagram showing an example of the structure of a light output pattern included in the backlight unit shown in FIG. 6.

FIG. 11 is a schematic diagram showing an example of an arrangement structure of light output patterns included in the backlight unit shown in FIG. 6.

FIG. 12 is a graph showing an example of a comparison result of a simulated image and light efficiency between backlight units according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. When describing the present invention with reference to the drawings, regardless of the drawing numbers, the same elements will be represented by the same element symbols or signs. When it is determined that the detailed description of the known configuration or function involved in the present invention will make the gist of the present invention unclear, the detailed description thereof will not be given.

Terms such as first, second, A, B, (a), and (b) may be used to describe elements of the present invention. These terms are only used to distinguish one element from another element, and the nature, order, order, number, etc. of these elements are not limited by these terms. If it is mentioned that an element is "connected", "coupled" or "connected" to another element, it should be understood that the element can be directly coupled or connected to Another element or another element may be "inserted" in between, or these elements may be "connected", "coupled" or "connected" to each other with yet another element inserted in between.

FIG. 1 is a view schematically showing the configuration of a display device 100 according to an embodiment of the present invention.

1, a display device 100 according to an embodiment of the present invention includes: a display panel 110 including an active area A/A and an inactive area N/A; and a gate driving circuit 120 and a data driving circuit for driving the display panel 110 130 and controller 140.

In the display panel 110, a plurality of gate lines GL and a plurality of data lines DL are arranged, and a sub-pixel SP is arranged in an area where the gate line GL and the data line DL cross each other.

The gate driving circuit 120 is controlled by the controller 140, and controls the driving timing of the plurality of sub-pixels SP by sequentially outputting scan signals to the plurality of gate lines GL arranged in the display panel 110.

The gate driving circuit 120 includes more than one gate driver integrated circuits (GDICs), and may be located only on one side of the display panel 110 or on both sides according to the driving mode.

Each gate driver integrated circuit (GDIC) can be connected to the bonding pad of the display panel 110 in a tape automated bonding (TAB) system or a chip on glass (COG) system, or, It can be implemented in a gate inpanel (GIP) system and directly arranged in the display panel 110. In some cases, each gate driver integrated circuit (GDIC) may be integrated and disposed in the display panel 110. Each gate driver integrated circuit (GDIC) can be implemented in a chip on film (COF) system in which it is installed on a film connected to the display panel 110.

The data driving circuit 130 receives the image data DATA from the controller 140 and converts the image data DATA into an analog type data voltage. Then, at the time point when the scan signal is applied to the gate line GL, the data driving circuit 130 outputs the data voltage to the data line DL, so that the sub-pixel SP exhibits the brightness corresponding to the image data DATA.

The data driving circuit 130 may include more than one source driver integrated circuits (SDICs).

Each source driver integrated circuit (SDIC) can include a shift register, a latch circuit, a digital-to-analog converter, and an output buffer.

Each source driver integrated circuit (SDIC) can be connected to the bonding pad of the display panel 110 in a tape-and-reel automatic bonding (TAB) system or a chip-on-glass (COG) system, or can be directly provided in the display panel 110 . In some cases, source driver integrated circuits (SDICs) may be integrated and disposed in the display panel 110. Each source driver integrated circuit (SDIC) can be implemented in a chip on film (COF) system. In this case, each source driver integrated circuit (SDIC) may be mounted on a film connected to the display panel 110, and may be electrically connected to the display panel 110 via wiring on the film.

The controller 140 supplies various control signals to the gate driving circuit 120 and the data driving circuit 130, and controls the operations of the gate driving circuit 120 and the data driving circuit 130.

The controller 140 can be mounted on a printed circuit board, a flexible printed circuit, etc., and is electrically connected to the gate drive circuit 120 and the data drive circuit 130 via the printed circuit board, the flexible printed circuit, etc.

The controller 140 causes the gate driving circuit 120 to output scanning signals according to the timing realized in each frame, convert the image data received from the outside into the data signal format used in the data driving circuit 130, and convert the converted image data Output to the data driving circuit 130.

In addition to the image data from the outside (for example, the host system), the controller 140 also receives various timing signals, including: vertical synchronization signal (VSYNC), horizontal synchronization signal (HSYNC), input data enable signal (DE), and Clock signal (CLK).

The controller 140 may generate various control signals using various timing signals received from the outside, and output the generated control signals to the gate driving circuit 120 and the data driving circuit 130.

For example, the controller 140 may output various gate control signals (GCS), including: gate start pulse (GSP), gate shift clock (GSC) and gate output enable signal (GOE), To control the gate drive circuit 120.

Here, the gate start pulse (GSP) controls the operation start timing of one or more gate driver integrated circuits (GDICs) of the gate drive circuit 120. The gate shift clock (GSC) is a clock signal commonly input to more than one gate driver integrated circuit (GDICs) and controls the shift timing of the scan signal. The gate output enable signal (GOE) specifies the timing information of the one or more gate driver integrated circuits (GDICs).

The controller 140 outputs various data control signals DCS, including: source start pulse (SSP), source sampling clock (source sampling clock, SSC), and source output enable signal (SOE) to control the data driving circuit 130 .

Here, the source start pulse (SSP) controls the data sampling start timing of one or more source driver integrated circuits (SDICs) of the data driving circuit 130. The source sampling clock (SSC) is a clock signal used to control the sampling timing of the data in the one or more source driver integrated circuits (SDIC). The source output enable signal (SOE) controls the output timing of the data driving circuit 130.

The display device 100 may further include a power management integrated circuit that supplies various voltages or currents to the display panel 110, the gate drive circuit 120, the data drive circuit 130, etc., or controls various voltages or currents to be supplied.

Each sub-pixel SP is defined by the intersection of a gate line GL and a data line DL, and according to the type of the display device 100, liquid crystal or light-emitting elements may be disposed therein.

For example, when the display device 100 is a liquid crystal display device, the display device 100 includes a light source device that emits light to the display panel 110, such as a backlight unit, and liquid crystals are provided in the sub-pixels SP of the display panel 110. By using the electric field formed by applying the data voltage to the sub-pixel SP to adjust the alignment of the liquid crystal, the brightness corresponding to the image data can be displayed and the image can be displayed.

FIG. 2 is a schematic diagram showing an example of the structure of a backlight unit included in the display device 100 according to an embodiment of the present invention.

2, a display device 100 according to an embodiment of the present invention includes: a display panel 110; and a backlight unit disposed under the display panel 110 and supplying light to the display panel 110.

Various structures may be provided between the backlight unit and the display panel 110. For example, the display panel 110 may be fixed to the backlight unit using the guide panel 400, the foam pad 500, etc., but the present invention is not limited thereto.

The backlight unit may include a cover bottom 201 to accommodate optical elements constituting the backlight unit and the like.

The printed circuit 202 may be provided on the bottom cover 201, and a plurality of light sources 203 may be provided on the printed circuit 202.

The printed circuit 202 may have a plate-like shape, and the reflective film 204 may be provided in at least some areas of the area where the light source 203 is not provided on the printed circuit 202. The reflective film 204 may be a reflective plate.

The light source protection part 205 may be provided on the plurality of light sources 203 and the reflective film 204. The light source protection part 205 can protect the plurality of light sources 203 and provide a function of diffusing the light emitted from the light sources 203. That is, the light source protection part 205 can directly contact the light source 203, protect the light source 203 and provide a light guiding function.

The transparent film 300 is disposed on the light source protection part 205, and a plurality of optical patterns 310 may be disposed on at least one of the bottom surface of the transparent film 300 and the top surface of the transparent film 300.

Here, the plurality of optical patterns 310 may be light control patterns. In addition, a plurality of optical patterns 310 may be disposed on the bottom surface of the transparent film 300 at positions corresponding to the plurality of light sources 203. Alternatively, a plurality of optical patterns 310 may be disposed on the top surface of the transparent film 300 at positions corresponding to the plurality of light sources 203. For example, each of the plurality of optical patterns 310 may be provided to correspond to a hole formed in the reflective film 204. In some cases, the area of the optical pattern 310 may be equal to the area of the hole of the reflective film 204. The optical pattern 310 can improve the image quality of the backlight unit by scattering, reflecting, or diffracting a part of the light vertically emitted from the light source 203. Also, the optical pattern 310 may transmit a part of the light emitted from the light source 203. In addition, the optical pattern 310 may be a light control pattern, which may transmit a part of light.

That is, by arranging the optical pattern 310 in the area where the intensity of the light emitted from the light source 203 is the highest, the area between the area where the light source 203 is provided (the area with high light intensity) and the area between the light sources 203 (light The brightness deviation between areas with low intensity), etc.

A diffusion film 206 that diffuses light incident from below may be provided on the transparent film 300. The diffusion film 206 may be a diffusion plate.

The color conversion sheet 207 or more than one optical sheet 208 may be disposed on the diffusion film 206.

3A to 3E are schematic diagrams showing examples of the specific structure of the backlight unit shown in FIG. 2.

3A, a plurality of light sources 203 are arranged on the printed circuit 202.

Each light source 203 may be, for example, a light emitting diode (LED), a sub-millimeter light emitting diode (mini LED), or a micro light emitting diode (μLED). Therefore, the light source 203 can be mounted and arranged on the printed circuit 202 in the form of a wafer, thereby reducing the thickness of the backlight unit. Moreover, the light source 203 may be of a flip chip type.

Each light source 203 may emit light in a white wavelength band or may emit light in a specific wavelength band (for example, a blue wavelength band).

3B, the reflective film 204 may be provided in at least some areas of the printed circuit 202 except for the area where the light source 203 is provided.

The reflective film 204 is formed so that the area corresponding to the light source 203 is open, and the reflective film 204 can be set and arranged on the printed circuit 202. The reflective film 204 reflects the light emitted from the light source 203 toward the front surface of the backlight unit to enhance the light efficiency of the backlight unit.

When the light sources 203 are provided in the form of a wafer, each light source 203 has a small size, so the height of the reflective film 204 may be greater than the height of the light source 203.

Therefore, the light laterally emitted from the light source 203 can be reflected by the side surface of the reflective film 204 and emitted to the front surface of the backlight unit, so that the light efficiency of the backlight unit can be further improved.

In some cases, a coated reflective film may be provided on the printed circuit 202.

That is, the front surface of the printed circuit 202 (facing the display panel 110) or the area other than the area where the light source 203 is provided may be coated with a reflective film to improve light efficiency.

In this case, the reflective film coated on the printed circuit 202 may be used as the reflective film 204, or may be provided together with the reflective film 204 to provide a reflective function.

3C, the light source protection part 205 may be provided on the plurality of light sources 203 and the reflective film 204.

The light source protection part 205 may contain, for example, resin.

When the light source protection portion 205 contains resin, the light source protection can be formed by providing a partition wall on the outside of the printed circuit 202 or in the peripheral area of the area where the plurality of light sources 203 are provided, and coating the partition wall with resin. Part 205.

The light source protection part 205 performs a function of protecting a plurality of light sources 203 provided on the printed circuit 202, and may be used to diffuse light emitted from the light source 203 and provide a function of guiding light.

That is, the light source protection part 205 can diffuse the light emitted from the light source 203 to the top surface of the light source protection part 205 more uniformly.

In the embodiment of the present invention, by disposing an optical pattern 310 with optical characteristics on the light source protection portion 205 at a position corresponding to the light source 203, the thickness of the backlight unit can be reduced and the uniformity of the image can be further improved.

3D, the transparent film 300 may be disposed on the light source protection part 205, and a plurality of optical patterns 310 may be disposed on the bottom surface of the transparent film 300. Also, a plurality of optical patterns 310 may be disposed on the top surface of the transparent film 300. Can be transparent by inserting an adhesive layer 209 in between The film 300 is bonded to the light source protection part 205. The adhesive layer 209 may be optical adhesive (OCA). The transparent film 300 may include, for example, PET, but the embodiment of the present invention is not limited thereto.

The plurality of optical patterns 310 provided on the bottom surface of the transparent film 300 may correspond to the plurality of light sources 203 provided on the printed circuit 202.

That is, at least a part of each optical pattern 310 may be set to overlap with the corresponding light source 203, and, considering the diffusion characteristics of light, each optical pattern 310 may be set to overlap with the area including the area where the corresponding light source 203 is provided. .

The optical pattern 310 has a specific reflectivity. And, the optical pattern 310 may scatter, reflect, diffract, or transmit a part of the light emitted from the light source 203.

For example, each optical pattern 310 may scatter the light emitted vertically (or approximately vertically) from the corresponding light source 203 and output the light in the vertical direction and the oblique direction. Alternatively, the optical pattern 310 may enable the light to be output to the area between the light sources 203 by reflecting the light vertically emitted from the light source 203 and allowing the reflective film 204 to reflect the light again.

In this way, by adjusting the light emission direction of the light vertically emitted from the light source 203 using the optical pattern 310, the image quality of the backlight unit can be improved. That is, since the light emitted from the light source 203 is scattered, reflected, diffracted, or transmitted by the optical pattern 310, the brightness uniformity of the backlight unit can be improved.

3E, the diffusion film 206 may be provided on the transparent film 300, and the color conversion sheet 207 may be provided on the diffusion film 206. More than one optical sheet 208 may be provided on the color conversion sheet 207.

Here, the positions where the diffusion film 206 and the color conversion sheet 207 are provided can be exchanged.

The diffusion film 206 diffuses the light emitted through the transparent film 300.

The color conversion sheet 207 may emit light of a specific wavelength band in response to light incident thereon.

For example, when the light source 203 emits light in the first wavelength band (for example, blue light), the color conversion sheet 207 may emit light in the second wavelength band (for example, green light) and light in the third wavelength band (for example, red light), In response to the light incident on it.

In some cases, the color conversion sheet 207 may only be provided on certain areas on the diffusion film 206.

For example, when the light source 203 emits light in the blue wavelength band, the color conversion sheet 207 may be provided only in a region other than the region of the display panel 110 corresponding to the region where the blue sub-pixel SP is provided. That is, the light that has not passed through the color conversion sheet 207 can reach the blue sub-pixel SP of the display panel 110.

Depending on the light source 203, the color conversion sheet 207 may not be provided.

For example, when the light source 203 emits light in the white wavelength band, or when the light-emitting surface of the light source 203 that emits light in the blue wavelength band is coated with a color conversion film that emits light in the green wavelength band and the light in the red wavelength band, it may not be Set the color conversion sheet 207.

In this way, in the embodiment of the present invention, by allowing the backlight unit to include the transparent film 300 containing the optical pattern 310 and various optical elements, where the optical pattern 310 is disposed at a position corresponding to the light source 203, the backlight unit can be reduced. And improve the image quality of the backlight unit.

A specific example of the optical pattern 310 provided on the transparent film 300 and an embodiment of the present invention will be described below.

FIG. 4 is a schematic diagram showing an embodiment of the structure of the backlight unit according to the embodiment of the present invention.

Referring to FIG. 4, the printed circuit 202 is provided on the bottom cover 201. The printed circuit 202 can be adhered through an adhesive tape 210 provided between the bottom cover 201 and the printed circuit 202.

A plurality of light sources 203 are provided on the printed circuit 202, and the reflective film 204 is provided on at least some of the areas other than the area where the light source 203 is provided.

Here, each light source 203 may be, for example, a light emitting diode (LED), and includes a light emitting part 203a including an n-type semiconductor layer, an active layer, and a p-type semiconductor layer and an electrode part 203b.

The light source protection part 205 is provided on the plurality of light sources 203 and the reflective film 204.

The transparent film 300 is disposed on the light source protection part 205 in which an optical pattern 310 is disposed at a position corresponding to the light source 203. Here, the optical pattern 310 provided on the bottom surface of the transparent film 300 may be a light modifying pattern (light modifying pattern) 311.

The diffusion film 206, the color conversion sheet 207, the optical sheet 208, and the like may be provided on the transparent film 300.

The light modification pattern 311 provided on the bottom surface of the transparent film 300 can be realized by printing a material with light blocking properties on the transparent film 300, and can be provided using, for example, a method _{of printing TiO 2 ink on the transparent film 300} Light modification pattern 311. When the light modification pattern 311 uses TiO ₂ , if the light modification pattern 311 is provided as one layer, the reflectance of the light modification pattern 311 may be 60% to 70%. And, the absorption/transmittance of the light modification pattern 311 may be 30% to 40%.

The light modification pattern 311 provided on the bottom surface of the transparent film 300 may be provided as a single layer or as a multilayer structure. For example, the light modification pattern 311 may be provided in two layers. Also, if the light modification pattern 311 is provided in two layers, the reflectance of the light modification pattern 311 may be 70 to 80%. And, the absorption/transmittance of the light modification pattern 311 may be 20% to 30%. However, the reflectance of the light modification pattern 311 is not limited to the above example. If _{the content of TiO 2} contained in the light modification pattern 311 increases or the thickness of the layer of the light modification pattern 311 becomes larger, the reflectance of the light modification pattern 311 can be increased. And the transmittance of the light modification pattern 311 can be reduced.

That is, as shown in FIG. 4, each light modification pattern 311 provided on the bottom surface of the transparent film 300 may include three layers.

Such a light-modifying pattern 311 can be realized by printing, for example, three times of light-modifying material on the transparent film 300, and the area of printing the light-modifying material can be reduced layer by layer. By upside down the transparent film 300 in which the light modification pattern 311 is disposed, and the upside down transparent film 300 is disposed on the light source protection part 205, the light modification pattern 311 can be disposed on the light source 203.

Therefore, the area of each light modification pattern 311 may be reduced downward in the transparent film 300, and the thickness of the central portion of the light modification pattern 311 may be greater than the thickness of the peripheral portion thereof.

That is, because the intensity of light emitted vertically from each light source 203 is the highest, the central portion of each light modification pattern 311 may have a greater thickness.

In this way, by disposing the light modification pattern 311 on the light source 203, the light emitted vertically from each light source 203 can be modified or blocked, and the hot spot phenomenon occurring in the area where the light source 203 is disposed can be prevented or reduced.

The transparent film 300 with the light modification pattern 311 provided thereon may be adhered to the light source protection part 205 using the adhesive layer 209.

Here, the adhesive layer 209 may be provided in at least some areas of the bottom surface of the transparent film 300 except for the area where the light modification pattern 311 is provided.

Therefore, the adhesive layer 209 is not disposed in the area where the light modification pattern 311 is disposed, and there may be an air gap between the light modification pattern 311 and the light source protection part 205.

The side portion of each light modification pattern 311 and the adhesive layer 209 may be separated from each other.

Since there is an air gap between the light modification pattern 311 and the light source protection portion 205, light laterally emitted from each light modification pattern 311 may be reflected by the air gap.

That is, the light laterally emitted from each light modification pattern 311 may be emitted at a large refraction angle through an air layer having a low refractive index or may be reflected by the air layer. The light reflected by the air layer again Reflected by the reflective film 204 and then emitted, it is possible to improve the light efficiency while assisting the light modification or light blocking function of the light modification pattern 311.

In this way, by using a structure in which the light modification pattern 311 and an air gap are provided at a position corresponding to each light source 203, the hot spot phenomenon can be prevented and the light efficiency of the backlight unit can be improved.

At this time, the light modification pattern 311 provided on the bottom surface of the transparent film 300 may be provided in a different structure according to the location where it is provided.

5A and 5B are schematic diagrams showing an example of the structure through the position of the light modification pattern included in the backlight unit shown in FIG. 4.

5A shows an example of the brightness presented by the backlight unit according to the structure of the light modification pattern 311, where <EX1> shows an example of the brightness measured when the light modification pattern 311 is set as a fixed structure, and <EX2> shows An example of the measured brightness when the light modification pattern 311 is set to a different structure according to the position.

As shown in <EX1> of FIG. 5A, when the light modification pattern 311a arranged in the peripheral area of the backlight unit and the light modification patterns 311c and 311d arranged in the central area (surrounded by the peripheral area) have the same structure, The brightness of the peripheral area of the backlight unit may be low.

That is, since the number of light sources 203 that supply light to the peripheral area of the backlight unit is relatively small compared to the number of light sources 203 that supply light to the central area, when the light modification patterns have the same light modification or light blocking characteristics When the 311 is arranged in the two areas, the brightness of the peripheral area may be lower than that in the central area of the backlight unit.

Therefore, as shown in <EX2> of FIG. 5A, by providing the light modification pattern 311a and the light modification pattern 311d having different structures in the peripheral area and the central area of the backlight unit, the brightness in the peripheral area of the backlight unit can be prevented or reduced. Reduce, and can make the brightness more uniform on the whole.

For example, the light modification pattern 311 may be provided such that the thickness T1 of the light modification pattern 311a provided in the peripheral area of the backlight unit is smaller than the thickness T2 of the light modification pattern 311d provided in the central area thereof.

Alternatively, the light modification pattern 311 may be arranged such that the area W1 of the thickest part of the light modification pattern 311b arranged adjacent to the peripheral area of the backlight unit is smaller than the area W2 of the thickest part of the light modification pattern 311d. That is, the area of the light modification pattern 311a or 311b provided in the peripheral area of the backlight unit or the area adjacent to the peripheral area having high light modification or blocking characteristics can be set to be small.

The light modification pattern 311 may be arranged such that the thickness of the light modification pattern 311 gradually decreases, or the area of the thickest part of the light modification pattern 311 gradually decreases from the central area to the peripheral area of the backlight unit.

In some cases, the light modification patterns 311 may be set to be different, so that the number of light sources 203 or the number of gaps between the light sources 203 are different in the central area and the peripheral area of the backlight unit.

Another example of a structure in which the light modification pattern 311 is provided on the bottom surface of the transparent film 300 will be described below with reference to FIG. 5B.

Here, the gap between the light sources 203 provided in the peripheral area of the backlight unit may be smaller than the gap between the light sources 203 provided in the central area of the backlight unit. That is, the light sources 203 can be more densely arranged in the peripheral area of the backlight unit, so that the brightness is more uniform or constant in the central area and the peripheral area of the backlight unit.

Since the light modification pattern 311 provided on the bottom surface of the transparent film 300 is set to correspond to the light source 203, the gap between the light modification pattern 311 provided in the peripheral area of the backlight unit can be compared with the light decoration pattern 311 provided in the central area. The gaps between the patterns 311 are different.

For example, the gap D1 in the first direction between the light modification patterns 311 disposed in the peripheral area of the backlight unit may be smaller than the gap D2 in the first direction between the light modification patterns 311 disposed in the central area. The gap D3 in the second direction between the light modification patterns 311 disposed in the peripheral area of the backlight unit may be smaller than the gap D4 in the second direction between the light modification patterns 311 disposed in the central area.

Here, the size, thickness, etc. of the light modification pattern 311 provided in the peripheral area of the backlight unit may be different from the size, thickness, etc. of the light modification pattern 311 provided in the central area of the backlight unit.

For example, as shown in FIG. 5B, the size S1 of the light modification patterns 311e and 311f provided in the peripheral area of the backlight unit may be smaller than the size S2 of the light modification patterns 311g provided in the central area of the backlight unit.

Alternatively, the light modification pattern 311 may have a multilayer structure as described above. In this case, the thickness of the light modification patterns 311e and 311f provided in the peripheral area of the backlight unit or the area of the thinnest part thereof may be smaller than the thickness of the light modification patterns 311e and 311f provided in the central area of the backlight unit or the area of the thickest part thereof. The thickness of the pattern 311g.

That is, by reducing the size of the light modification patterns 311e and 311f provided in the peripheral area of the backlight unit, the light modification patterns can be set to correspond to the light sources 203 provided with a smaller gap. Therefore, it is possible to prevent or reduce the occurrence of a hot spot at a position corresponding to the light source 203 in the peripheral area of the backlight unit.

By reducing the degree to which the light emitted from the light source 203 is modified or blocked in the peripheral area of the backlight unit, the intensity of the emitted light can be increased to prevent or reduce the brightness reduction in the peripheral area of the backlight unit, and make the entire backlight unit The area exhibits a more uniform brightness.

In this way, by disposing the light modification patterns 311 in different structures based on the area of the backlight unit, it is possible to prevent or reduce the brightness reduction in the peripheral area of the backlight unit, and it is possible to improve the brightness uniformity.

By adjusting the structure in which the light modification pattern 311 is provided, the hot spot phenomenon in the backlight unit can be prevented or reduced, and the brightness uniformity can be improved.

In the embodiment of the present invention, it is possible to provide a means capable of improving the image quality of the backlight unit and increasing the light efficiency by diffracting the light vertically emitted from the light source 203.

FIG. 6 is a schematic diagram showing the structure of a backlight unit according to an embodiment of the present invention.

6, the printed circuit 202 adhered to the bottom cover 201 through the adhesive tape 210 is disposed on the bottom cover 201, and a plurality of light sources 203 are disposed on the printed circuit 202. The reflective film 204 is provided in at least some areas of the printed circuit 202 except for the area where the light source 203 is provided.

The light source protection part 205 is provided on the plurality of light sources 203 and the reflective film 204, and the transparent film 300 is provided on the light source protection part 205, wherein the optical pattern 310 is provided at a position corresponding to the light source 203.

The transparent film 300 and the light source protection part 205 may be bonded by an adhesive layer 209. The diffusion film 206, the color conversion sheet 207, the optical sheet 208, and the like may be provided on the transparent film 300.

Here, the optical pattern 310 provided on the bottom surface of the transparent film 300 may be the diffraction pattern 312. The refractive index of the diffraction pattern 312 may be higher than the refractive index of the transparent film 300.

Therefore, the light emitted vertically from each light source 203 may be diffracted by the corresponding diffraction pattern 312 and may be incident on the transparent film 300 at a large refraction angle (for example, a non-vertical refraction angle).

That is, since the light passing through the diffraction pattern 312 is incident on the transparent film 300 at a refraction angle capable of undergoing total reflection, the light incident on the transparent film 300 may undergo total reflection and propagate in the transparent film 300.

A plurality of light output patterns 320 having a refractive index higher than that of the transparent film 300 may be provided on the transparent film 300.

Therefore, when light undergoes total reflection in the transparent film 300 to reach the bottom surface of each light output pattern 320, since the refraction angle is smaller than the incident angle, the light may be emitted to the outside via the light output pattern 320.

In this way, because the light emitted vertically from each light source 203 is incident on the transparent film 300 in a state where its optical path is adjusted by the diffraction pattern 312, light loss is reduced or alleviated.

Since the light totally reflected in the transparent film 300 is emitted from the position where the light output pattern 320 is provided, the area or direction of the light emitted on the transparent film 300 may be adjusted based on the position where the light output pattern 320 is provided.

Therefore, the loss of light emitted from the light source 203 can be reduced or minimized to improve the image quality and light efficiency of the backlight unit by controlling the light emission position, and reduce the power consumption of the backlight unit.

FIG. 7 is a schematic diagram of an example of the structure of a transparent film 300 in which a diffraction pattern 312 and a light output pattern 320 are arranged, and the transparent film 300 is included in the backlight unit shown in FIG. 6.

Referring to FIG. 7, a plurality of diffraction patterns 312 are disposed on the bottom surface of the transparent film 300 at positions corresponding to the light source 203. A plurality of light output patterns 320 are provided on the top surface of the transparent film 300.

Here, the base film 330 is provided between the transparent film 300 and the diffraction pattern 312. The base film 330 and the diffraction pattern 312 may be collectively referred to as a holographic film.

That is, the diffraction pattern 312 may be disposed on the bottom surface of the transparent film 300, and the base film 330 may be disposed between the transparent film 300 and the diffraction pattern 312 to facilitate the arrangement of the diffraction pattern 312, or to enhance the transparent film 300 The total reflection effect of the light.

The refractive index of the base film 330 may be lower than the refractive index of the diffraction pattern 312. Therefore, light incident on the base film 330 via the diffraction pattern 312 may be incident at a total reflection angle.

The refractive index of the base film 330 may be equal to or almost close to the refractive index of the transparent film 300. Here, when the refractive index of the base film 330 is different from the refractive index of the transparent film 300, by setting the refractive index of the transparent film 300 to be at least slightly larger than the refractive index of the base film 330, it is possible to prevent The excessive total reflection of the light, the light is not emitted from the light output pattern 320.

The diffraction pattern 312 may be provided in the form of a specific structure repeated on the bottom surface of the base film 330, and may be provided in, for example, a lattice form. The diffraction pattern 312 may be provided in various forms capable of diffracting light.

That is, the form of the diffraction pattern 312 is not limited to a specific form, and, due to the diffraction pattern 312 and the difference between the base film 330 and the transparent film 300, the light emitted from the light source 203 and passing through the diffraction pattern 312 is on the transparent film 300. In experience total reflection.

The light reaching the light output pattern 320 is emitted to the outside via the light output pattern 320, where the light output pattern 320 is provided on the transparent film 300 and has a refractive index higher than that of the transparent film 300.

For example, when light incident on the transparent film 300 at an angle of θ1 reaches the light output pattern 320 having a higher refractive index than that of the transparent film 300, the light is incident at an angle θ2 smaller than θ1, and therefore may be emitted to the light output pattern 320 Outside.

In this way, by using the light output pattern 320 to adjust the emission path of the light incident on the transparent film 300 without light loss, it is possible to improve the light efficiency as a whole and improve the brightness uniformity.

A layer for enhancing the total reflection effect may be additionally provided on the transparent film 300.

FIG. 8 is a schematic diagram showing another example of the structure of the transparent film 300 in which the diffraction pattern 312 and the light output pattern 320 are arranged, and the transparent film 300 is included in the backlight unit shown in FIG. 6.

Referring to FIG. 8, a holographic film including a base film 330 and a diffraction pattern 312 may be disposed on the bottom surface of the transparent film 300 at a position corresponding to the light source 203.

The light output pattern 320 may be provided on the transparent film 300.

Here, the coating layer 340 may be provided in at least some areas of the transparent film 300 other than the area where the light output pattern 320 is provided. Some parts of the light may be refracted by the coating 340, and other parts of the light may be reflected by the coating 340. The refractive index of the coating 340 may be less than the refractive index of the transparent film 300.

That is, when the light undergoing total reflection in the transparent film 300 reaches the coating 340 having a refractive index lower than that of the transparent film 300, the light cannot be emitted to the outside of the transparent film 300, and therefore the light in the transparent film 300 can be enhanced. The total reflection effect.

When the light undergoing total reflection in the transparent film 300 reaches the light output pattern 320, the light may be emitted to the outside via the light output pattern 320.

Therefore, by providing the coating 340 and the light output pattern 320, the area where the light is emitted on the transparent film 300 can be more accurately controlled.

The coating 340 may be further disposed on the outer surface of the light output pattern 320.

FIG. 9 is a schematic diagram of still another example of the structure of the transparent film 300 in which the diffraction pattern 312 and the light output pattern 320 are arranged, and the transparent film 300 is included in the backlight unit shown in FIG. 6.

9, the holographic film may be disposed on the bottom surface of the transparent film 300 at a position corresponding to the light source 203, and the light output pattern 320 may be disposed on the transparent film 300.

A coating 340 having a refractive index lower than that of the transparent film 300 may be provided on the transparent film 300, and the coating 340 may also be provided on the light output pattern 320.

That is, since the light incident on the light output pattern 320 is incident at an increased incident angle, even if the coating 340 having a low refractive index is provided on the light output pattern 320, the light can be emitted to the outside via the light output pattern 320 . Therefore, the coating 340 may perform a function of enhancing the light guide function of the transparent film 300 and protecting the light output pattern 320 in an area where the light output pattern 320 is not provided.

The coating 340 may be disposed on the transparent film 300 and the light output pattern 320 at a fixed height so that the upper surface of the coating 340 (above the light output pattern 320) is flat or parallel to the transparent film 300.

Therefore, the diffusion film 206 and the like can be easily provided on the transparent film 300 in which the light output pattern 320 is provided.

FIG. 10 is a schematic diagram showing an example of the structure of the light output pattern 320 included in the backlight unit shown in FIG. 6.

10, in consideration of the characteristics of the emitted light, the light output pattern 320 provided on the transparent film 300 may have various shapes.

For example, each light output pattern 320 may have a hemispherical shape in which the horizontal radius and the vertical radius are the same. Using the light output pattern 320 of a hemispherical shape having the same horizontal radius and vertical radius can achieve a general viewing angle.

Alternatively, each light output pattern 320 may have an elliptical shape in which the semi-major axis is greater than the semi-minor axis. For example, the semi-minor axis may be 60% of the semi-major axis. The use of the light output pattern 320 having an elliptical shape with a semi-major axis larger than the semi-minor axis can achieve wide viewing angle characteristics.

Alternatively, each light output pattern 320 may have a shape in which the top surface is flat and the top surface is narrower than the bottom surface. A part of such a light output pattern 320 may have a trapezoidal shape. I.e. use the top table The structure of the light output pattern 320 with a flat surface (for example, parallel to the bottom surface) can achieve narrow viewing angle characteristics, and the use of this structure can enhance the front luminance.

Depending on the characteristics of the display device 100, this structure of the light output pattern 320 may be implemented in various forms. In some cases, the light output patterns 320 of structures having different viewing angle characteristics may be mixed and arranged.

The position, density, etc. of the light output pattern 320 may be determined according to the position of the light source 203.

FIG. 11 is a schematic diagram showing an example of the arrangement structure of the light output pattern 320 included in the backlight unit shown in FIG. 6.

11, the diffraction pattern 312 is provided on the light source 203, and the transparent film 300 is provided on the diffraction pattern 312. The light output pattern 320 is provided on the transparent film 300.

Here, the density of the light output pattern 320 arranged in a region adjacent to one light source 203 (for example, overlapping with the light source 203) may be less than that of the space arranged adjacent to the light source 203 (for example, not adjacent to the light source 203). 203 overlap) the density of the light output pattern 320 in the area.

That is, the number of light output patterns 320 arranged in the first area Area1 adjacent to one light source 203 may be smaller than that of the light output patterns 320 arranged in the second area Area2 adjacent to the space between the light sources 203. Number, where the second area Area2 has the same area as the first area Area1.

For example, the density of the light output patterns 320 provided in the central area of the backlight unit may be greater than the density of the light output patterns 320 provided in the peripheral area of the backlight unit. Therefore, it is possible to prevent or reduce (compared to the light intensity of the central area) the decrease in the brightness of the peripheral area of the backlight unit having a relatively small light intensity.

In this way, by adjusting the position of the light output pattern 320 on the transparent film 300 according to the position of the light source, the light path of the light emitted from the light source 203 can be effectively controlled, and the brightness uniformity of the backlight unit can be improved as a whole And image quality.

FIG. 12 is a graph showing an example of a comparison result of a simulated image and light efficiency between backlight units according to an embodiment of the present invention.

12, case #1 represents a case where the optical pattern 310 provided in the backlight unit corresponding to the light source 203 is a light modification pattern 311, and case #2 represents a case where the optical pattern 310 provided in the backlight unit is a winding Example of shooting pattern 312.

As shown in FIG. 12, by disposing an optical pattern 310 such as a light modification pattern 311 or a diffraction pattern 312 at a position corresponding to the light source 203, it can be seen that hot spots are prevented and brightness uniformity is improved.

When the diffraction pattern 312 is provided, the light loss due to the optical pattern 310 is reduced, so it can be seen that the light efficiency is further improved.

According to an embodiment of the present invention, by disposing an optical pattern 310 that scatters, reflects, or diffracts light on the light source 203 of the backlight unit, the hot spot phenomenon of the backlight unit can be prevented and the brightness uniformity can be improved.

Therefore, the thickness of the backlight unit can be reduced and high image quality can be provided.

By disposing the diffraction pattern 312 having a refractive index higher than that of the transparent film 300 on the bottom surface of the transparent film 300, the light passing through the diffraction pattern 312 undergoes total reflection in the transparent film 300, thereby preventing or reducing Loss of light emitted from the light source 203.

By using the output pattern 320 provided on the transparent film 300 and having a refractive index higher than that of the transparent film 300 to control the light emission path, the image quality of the backlight unit can be improved and the light efficiency can be enhanced to reduce power consumption.

The above description only exemplifies the technical concept of the present invention, and a person with ordinary knowledge in the technical field to which the present invention belongs can make various modifications and changes without departing from the basic characteristics of the present invention. Therefore, the embodiments disclosed in this specification are not used to limit the technical idea of the present invention, but are used to explain the technical idea of the present invention. Therefore, the scope of the technical idea of the present invention is not limited thereto. The scope of the present invention is defined by the appended claims, and all technical ideas within the equivalent scope should be construed as belonging to the scope of the present invention.

The present invention claims the priority rights of Korean Patent Application No. 10-2018-0156352 filed on December 6, 2018 and Korean Patent Application No. 10-2019-0134430 filed on October 28, 2019, which are based on All purposes are incorporated herein by reference, as if fully stated in this article.

100: display device

110: display panel

120: Gate drive circuit

130: data drive circuit

140: Controller

A/A: Active area

DATA: image data

DCS: data control signal

DL: Data line

GCS: Gate control signal

GL: Gate line

N/A: Inactive area

SP: sub pixel

Claims (23)

A display device, including: a display panel; and a backlight unit, including: a printed circuit; a light-emitting device located on the printed circuit; a transparent film, including on a bottom surface of the transparent film facing the printed circuit A holographic film comprising at least one optical pattern that overlaps the light-emitting device and changes the angle of a part of the light emitted by the light-emitting device; a light output pattern is located on an upper surface of the transparent film Above, the portion of the light having the changed angle passes through the light output pattern toward the display panel, and the refractive index of the light output pattern is greater than the refractive index of the transparent film, so that the light leaving the portion of the light output pattern is refracted The angle is smaller than the incident angle of the light entering the portion of the light output pattern; and a coating is located on the transparent film, the refractive index of the coating is lower than the refractive index of the transparent film. The display device according to claim 1, wherein the optical pattern changes the angle of another part of the light emitted by the light-emitting device, and the coating reflects the other part of the light having the changed angle toward the bottom surface of the transparent film . The display device according to claim 1, wherein the coating layer overlaps the light output pattern. The display device according to claim 3, wherein the light passing through the portion of the light output pattern with a changed angle further passes through the coating. The display device according to claim 3, wherein an upper surface of the coating is flat. The display device according to claim 1, wherein the holographic film further comprises: a base film located between the bottom surface of the transparent film and the optical pattern, and the refractive index of the base film is lower than that of the optical pattern rate. The display device according to claim 6, wherein the at least one optical pattern is provided on a bottom surface of the base film in a lattice shape. The display device according to claim 6, wherein the refractive index of the base film is equal to or lower than the refractive index of the transparent film. The display device according to claim 6, wherein the optical pattern is a diffraction pattern, and the refractive index of the optical pattern is greater than the refractive index of the transparent film. The display device according to claim 1, wherein the light output pattern has an oval shape. The display device according to claim 10, wherein half of the major axis of the elliptical shape is equal to half of the minor axis of the elliptical shape. The display device according to claim 10, wherein half of the major axis of the elliptical shape is greater than half of the minor axis of the elliptical shape. The display device according to claim 1, wherein an upper surface of the light output pattern is parallel to a lower surface of the light output pattern. The display device according to claim 13, wherein the light output pattern has a trapezoidal shape. The display device according to claim 1, further comprising: a bottom cover located under the printed circuit; and an adhesive tape for bonding the printed circuit to the bottom cover. The display device according to claim 1, wherein the holographic film includes: a first plurality of optical patterns located in an area overlapping the light-emitting device, and a second plurality of optical patterns located between the plurality of light-emitting devices In another area where the spaces overlap each other, the density of the first plurality of optical patterns is greater than the density of the second plurality of optical patterns. The display device according to claim 1, further comprising: a reflective film accommodating and exposing the light-emitting device, the reflective film having a height greater than the height of the light-emitting device, and configured to reflect light emitted from the light-emitting device. A backlight unit includes: a printed circuit; a light emitting device located on the printed circuit; a transparent film including an optical pattern on a bottom surface of the transparent film facing the printed circuit, the optical pattern and the light emitting device Overlap and change the angle of a part of the light emitted by the light-emitting device; a diffuser film on the transparent film; a light output pattern on an upper surface of the transparent film and below the diffuser film, with a changed angle The portion of the light passing through the light output pattern toward the diffusion film, the refractive index of the light output pattern is greater than the refractive index of the transparent film, so that the refraction angle of the light leaving the portion of the light output pattern is smaller than that of entering the light output The incident angle of the light of the part of the pattern; and a coating layer located between the transparent film and the diffusion film, the refractive index of the coating layer being lower than the refractive index of the transparent film. The backlight unit according to claim 18, further comprising: a color conversion sheet on the diffusion film; and one or more optical sheets on the color conversion sheet. A backlight unit includes: a plurality of light sources arranged on a printed circuit; a reflective film arranged in at least one area different from another area on the printed circuit where the plurality of light sources are arranged; a light source protection part, Arranged on the plurality of light sources and the reflective film; a transparent film arranged on the light source protection part; and a plurality of light modification patterns arranged at positions corresponding to the plurality of light sources on a bottom surface of the transparent film ; Wherein, there is an air gap between the plurality of light modification patterns and the light source protection portion. The backlight unit according to claim 20, wherein the thickness of a central portion in at least one of the plurality of light modification patterns is greater than the thickness of the peripheral portion thereof. The backlight unit according to claim 20, wherein the plurality of light modification patterns comprise: a first light modification pattern arranged in a peripheral area of a display panel; and a second light modification pattern arranged on the display panel In and in a central area of the panel, the thickness of the first light modification pattern is smaller than the thickness of the second light modification pattern, or the area of the first light modification pattern is smaller than the area of the second light modification pattern. The backlight unit according to claim 20, further comprising: an adhesive layer disposed between the light source protection part and the transparent film, and wherein the adhesive layer is disposed on and provided with the plurality of light modification patterns Another area is different in at least one area, and the edge of each of the plurality of light modification patterns is separated from the adhesive layer.

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