KR20130046862A - Backlight unit and lighting apparatus including the same - Google Patents

Abstract

PURPOSE: A backlight unit and a lighting apparatus including the same are provided to minimize the width of a bezel area by changing the shape of a bottom cover. CONSTITUTION: A bottom cover(170) includes a bottom surface, a first protrusion part, and a second protrusion part. A panel guide part(180) includes a second through hole(182). A top cover(160) includes a third through hole(162). A fastening member(110) passes through first to third through holes to connect the bottom cover, the panel guide part, and the top cover. An optical module(140) is inserted into the top edge of the first protrusion part. [Reference numerals] (AA,CC) Bezel area; (BB) Gap

Description

Backlight unit and lighting apparatus including the same

Embodiments relate to a backlight unit and a lighting device including the same.

In general, typical large display devices include a liquid crystal display (LCD) or a plasma display panel (PDP).

Unlike the self-luminous PDP, the LCD requires a separate backlight unit due to the absence of its own light emitting device.

The backlight unit used in LCD is classified into an edge type backlight unit and a direct type backlight unit according to the position of the light source. In the edge type, the light source is disposed on the left and right sides or the top and bottom sides of the LCD panel and the light guide plate is used. Since the light is evenly distributed on the front surface, the light is uniform and the panel thickness can be made ultra thin.

The direct method is a technology generally used for a display of 20 inches or more. Since a plurality of light sources are disposed under the panel, it has an advantage of superior light efficiency compared to an edge method, and thus is mainly used for a large display requiring high brightness.

In the direct backlight unit, various sheets such as a diffusion sheet, a prism sheet, and a protective sheet are stacked on a diffusion plate for diffusing and homogenizing light from a light source, and light emitting elements and reflecting plates are disposed at predetermined intervals below the diffusion plate. .

When a predetermined space is secured between the light emitting device and the diffuser plate, it is possible to secure a uniform light distribution without generating a hot spot on the front surface, but there is a problem in that the entire backlight unit becomes thick.

There is an attempt to improve the uniformity of the luminance while reducing the thickness of the backlight unit by forming a light incident surface on the lower side of the light guide plate to integrate the light source and the light guide plate.

Cold Cathode Fluorescent Lamp (CCFL) was used as a light source of the conventional edge or direct backlight unit. However, the CCFL-based backlight unit consumes a considerable amount of power since power is always supplied to the CCFL, has a color reproduction rate of about 70% compared to the CRT, and may cause environmental pollution problems due to the addition of mercury.

As a substitute for solving the above problems, research on a backlight unit using a light emitting diode (LED) has been actively conducted. When the LED is used as a backlight unit, the LED array can be partially turned on and off, which can drastically reduce the power consumption.In the case of the Red Green Blue (RGB) LED, the National Television System Committee (NTSC) Television System Committee) Provides more vivid picture quality to consumers by exceeding 100% of the color reproduction range specification.

1 is a cross-sectional view showing the structure of a general backlight unit.

As shown in FIG. 1, the backlight unit includes a light guide plate 20, a reflector 30, an optical member 40, and a light source module 50. It may include.

In addition, the backlight unit may further include a top chassis 60, a bottom chassis 70, and a panel guide module 80. Here, the panel guide module 80 may support the display panel 90, and the top chassis 60 may be connected to the panel guide module 80. At least one groove 22 is formed under the light guide plate 20, and the optical member 40 may be disposed on the light guide plate 20. The light source module 50 includes a substrate 52 and a light source 54 arranged on the substrate 52, which may be disposed in each groove 22 of the light guide plate 20.

In a general backlight unit having the above-described structure, the optical member 40 is fixed by the protrusion 10 protruding from the bottom chassis 70. In addition, the top chassis 60, panel guide module 80 and the bottom chassis 70 are coupled to each other by screws (6). Therefore, in order to secure space for the screw 6 and the protrusion 10, the bottom cover 70, as shown in Fig. 1, must have an extended structure protruding in the horizontal plane, so that the bezel area There is a problem of widening.

Republic of Korea Patent Publication No. 10-2011-0108832 ("light emitting device, light unit and display device having the same", published October 06, 2011)

Embodiments provide a backlight unit capable of minimizing the width of a bezel and an illumination device including the same.

The backlight unit of the embodiment may include a bottom surface, a first protrusion extending from the bottom surface in a first direction about the first side of the bottom surface, and a second second portion different from the first direction about the first side; Bottom cover having a second protrusion extending from the bottom surface in a direction and having a first through hole formed therein, a panel guide portion having a second through hole, a top cover having a third through hole, the first, second and And a fastening member for fastening the bottom cover, the panel guide part, and the top cover through a third through hole, and an optical module inserted into and fixed to the top edge of the first protrusion.

The bottom surface may further have at least one second side different from the first side, and the first protrusion may extend from the bottom side in the first direction about the second side to protrude. The second protrusion extends from the bottom surface in the second direction about the second side, and the first through hole is formed.

The first direction and the second direction may be opposite to each other.

The thickness of the first protrusion and the thickness of the second protrusion may be different from each other or may be the same. The thickness of the first protrusion may be different from or the same as the thickness of the bottom surface. The thickness of the second protrusion may be different from or the same as the thickness of the bottom surface.

The first protrusion and the second protrusion are alternately formed to extend from the bottom surface, or are formed to extend from the bottom surface on the same straight line.

The width of the first protrusion and the width of the second protrusion may be the same or may be different from each other.

The first protrusion has a fastening protrusion at the top edge, and the optical member is inserted into and fixed to the fastening protrusion. The fastening member may be a screw.

In addition, the width of the top edge of the first protrusion may be less than the width of the bottom of the first protrusion. The first protrusion may widen toward the bottom from the top edge.

The plurality of first protrusions and the plurality of second protrusions may be alternately disposed or parallel to each other.

The lighting apparatus according to the embodiment may further include a display panel including the backlight unit and receiving light from the backlight unit.

Embodiments may minimize the width of the bezel area by modifying the shape of the bottom cover, and further maximize the active area of the display panel.

1 is a cross-sectional view showing the structure of a general backlight unit.
2 is a cross-sectional view illustrating a backlight unit according to an embodiment.
3 is a perspective view illustrating a bottom cover according to the embodiment.
4 is a perspective view illustrating a bottom cover according to another exemplary embodiment.
5 is a perspective view of the first protrusion and the optical member according to the embodiment.
6 is a perspective view of a first protrusion and an optical member according to another embodiment.
7 illustrates a display module having a backlight unit according to an embodiment.
8 illustrates a display device according to an embodiment.
9 is a diagram illustrating a display device according to another exemplary embodiment.

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

In the description of this embodiment, in the case of being described as being formed on the "upper" or "on or under" of each element, on or under is meant to encompass both that the two elements are in direct contact with each other or that one or more other elements are indirectly formed between the two elements do.

Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

2 is a cross-sectional view illustrating a backlight unit according to an embodiment.

As shown in FIG. 2, the backlight unit includes a light guide plate 120, a reflector 130, an optical member 140, and a light source module 150. It may include.

The backlight unit may include a top cover (or top chassis) 160, a bottom cover (or a bottom chassis) 170, and a panel guide. It may further include a) (or a panel guide module) (180).

The panel guide unit 180 may support the display panel 190, and the top cover 160 may be connected to the panel guide unit 180.

Subsequently, at least one groove 124 may be formed on the lower surface of the light guide plate 120, and the optical member 140 may be disposed on the upper surface. Here, the groove 124 of the light guide plate 120 may have a triangular, rectangular, or trapezoidal shape in cross section. In some cases, when the groove 124 cross-sectional shape of the light guide plate 120 is trapezoidal, of the first and second side surfaces facing each other, the first side of the groove 124 is perpendicular to the bottom surface of the groove 124. The second side surface of the groove 124 may be inclined with respect to the bottom surface of the groove 124.

Alternatively, when the groove 124 cross-sectional shape of the light guide plate 120 is trapezoidal, the first and second side surfaces facing each other are inclined with respect to the bottom surface of the groove 124, and the first side and the bottom of the groove 124 are inclined. The inclination angle between the surfaces may be smaller than the inclination angle between the second side and the bottom surface of the groove 124.

For example, when the cross-sectional shape of the groove 124 of the light guide plate 120 is triangular, the first side of the groove 124 is one of the first and second side surfaces facing each other and meeting at a peak point. The second side of the groove 124 may be inclined with respect to the horizontal plane parallel to the upper surface of the light guide plate 120. Here, the angle between the first and second side facing each other may be about 30-120 degrees.

The ratio of the height of the groove 124 of the light guide plate 120 to the overall thickness of the light guide plate 120 may be about 0.3-0.7: 1. In addition, the light guide plate 120 may be formed of an acrylic resin such as polymethylmethacrylate (PMMA), polyethylene terephthlate (PET), cyclic olefin copolymers (COC), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), and MS (Mathacylate). styrene) resin can be any one.

Next, the light source module 150 may be disposed in each groove 124 of the light guide plate 120.

Here, the light source module 150 may include a substrate 152 and at least one light source 154 disposed on the substrate 152, wherein both of the substrate 152 and the light source 154 are formed of the light guide plate 120. It may be disposed inside the groove 124.

In some cases, the substrate 152 may be disposed outside the groove 124 of the light guide plate 120, and the light source 154 may be disposed inside the groove 124 of the light guide plate 120.

The substrate 152 may be formed with an electrode pattern for electrical connection to the light source 154, a PCB made of any one material selected from polyethylene terephthalate (PET), glass, polycarbonate (PC), silicon (Si) (Printed Circuit Board) It may be a substrate or may be formed in a film form.

In addition, the substrate 152 may selectively use a single layer PCB, a multilayer PCB, a ceramic substrate, a metal core PCB, or the like.

At least one light source 154 may be disposed on the substrate 152, and the light source 154 may be a side view type light emitting diode. In some cases, the light source 154 may be a top view type light emitting diode. As such, the light source 154 may be a light emitting diode chip, and the light emitting diode chip may include a blue LED chip or an ultraviolet LED chip or a red LED chip, a green LED chip, a blue LED chip, and yellow green. green) may be configured in the form of a package combining at least one or more of the LED chip, white LED chip.

Here, the white LED may be implemented by combining yellow phosphor on the blue LED, or simultaneously using red phosphor and green phosphor on the blue LED, and yellow phosphor on the blue LED. Yellow phosphor, red phosphor, and green phosphor may be simultaneously used.

Subsequently, the reflector 130 may be disposed on the lower surface of the light guide plate 120.

That is, the reflector 130 may be disposed between the light guide plate 120 and the bottom cover 170, and may extend from the lower surface of the light guide plate 120 to the side surface.

Here, the reflector 130 is not formed under the substrate 152 of the light source module 150, but may be formed under the substrate 152 of the light source module 150 in some cases.

The reflector 130 may be formed on at least one of the groove 124 side of the light guide plate 120 and the bottom surface of the groove 124.

Here, the reflector 130 may include at least one of a metal and a metal oxide. For example, the reflector 130 may have a high reflectance such as aluminum (Al), silver (Ag), gold (Au), or titanium dioxide (TiO ₂ ). The branch may comprise a metal or metal oxide.

Next, the optical member 140 may be disposed on the upper surface of the light guide plate 120.

Here, the optical member 140 is to diffuse the light emitted through the light guide plate 120, and may form an uneven pattern on the upper surface to increase the diffusion effect.

In addition, the optical member 140 may be formed of a plurality of layers, the uneven pattern may have a top surface or on the surface of any one layer.

In addition, the uneven pattern may have a stripe shape disposed along the light source module 150.

At this time, the uneven pattern has a portion protruding to the surface of the optical member 140, the protruding portion is composed of a first surface and a second surface facing each other, the angle between the first surface and the second surface is an obtuse angle or an acute angle Can be.

In some cases, the optical member 140 may include at least one sheet, and may include a diffusion sheet, a prism sheet, a brightness enhancement sheet, and the like. Here, the diffusion sheet diffuses the light emitted from the light source, and the prism sheet guides the diffused light to the light emitting area, and the brightness diffusion sheet strengthens the brightness.

3 and 4 are perspective views showing the bottom cover 170 according to the embodiment.

Bottom cover 170 according to an embodiment has a bottom surface 172, first and second protrusions 174 and 176. The bottom surface 172 has a first side 171. The first protrusion 174 extends from the bottom surface 172 in the first direction about the first side 171 to protrude. The second protrusion 176 extends from the bottom surface 172 in a second direction different from the first direction with respect to the first side 171 and has a first through hole 175 formed therein.

In addition, the bottom surface 172 further has at least one second side 179 that is different from the first side. The first protrusion 174 extends from the bottom surface 172 in the first direction about the second side 179 to protrude. The second protrusion 176 extends from the bottom surface 172 in the second direction about the second side 179 and protrudes, and a first through hole 175 is formed.

As shown in FIGS. 3 and 4, the first direction and the second direction may be opposite to each other. That is, the angle between the first direction and the second direction may be 180 degrees. However, this embodiment is not limited to this. That is, the angle between the first direction and the second direction may be less than 180 ° and greater than 90 °.

3 and 4, the second side 179 is shown as the side opposite to the first side 171, but the present invention is not limited thereto. That is, the second side may be one of the sides adjacent to the first side 171.

The panel guide part 180 illustrated in FIG. 2 has a second through hole 182, and the top cover 160 has a third through hole 162. At this time, the fastening member 110 penetrates the first, second and third through holes 175, 182, and 162 to fasten the bottom cover 170, the panel guide part 180, and the top cover 160.

In some embodiments, the fastening member 110 may be a screw that couples the bottom cover 170, the panel guide part 180, and the top cover 160 to each other.

In addition, the thickness t1 of the first protrusion 174 and the thickness t2 of the second protrusion 176 formed on the bottom cover 170 may be the same as or different from each other. For example, the thickness t1 of the first protrusion 174 may be larger or smaller than the thickness t2 of the second protrusion 176.

In addition, the thickness t1 of the first protrusion 174 may be different from the thickness t3 of the bottom surface 172. For example, the thickness t1 of the first protrusion 174 may be larger or smaller than the thickness t3 of the bottom surface 172. In addition, the thickness t2 of the second protrusion 174 may be the same as the thickness t3 of the bottom surface 172.

In addition, the width w1 of the first protrusion 174 and the width w2 of the second protrusion 176 may be the same or may be different from each other. If the width w1 of the first protrusion 174 is smaller than the width w2 of the second protrusion 176, the number of the first protrusions 174 is greater than the number of the second protrusions 176. However, when the width w1 of the first protrusion 174 is larger than the width w2 of the second protrusion 176, the number of the first protrusions 174 is smaller than the number of the second protrusions 176.

As shown in FIG. 3, at the first side 171, the first protrusion 174 and the second protrusion 176 may be alternately formed to extend from the bottom surface 172 in the first and second directions, respectively. 4, at the first side 171, the first protrusion 174 and the second protrusion 176 extend from the bottom surface 172 in the first and second directions on the same straight line, respectively. It may be formed.

As shown in FIGS. 3 and 4, the bottom cover 170 may have a plurality of first protrusions 174 and a plurality of second protrusions 176, but the present exemplary embodiment is not limited thereto. That is, the bottom cover 170 may have only one first protrusion 174 and one second protrusion 176.

If there are a plurality of first and second protrusions 174 and 176, respectively, as shown in FIG. 3, the plurality of first protrusions 174 and the plurality of second protrusions 176 alternately with each other. Can be arranged. Alternatively, when there are a plurality of first and second protrusions 174 and 176, respectively, as illustrated in FIG. 4, the plurality of first protrusions 174 and the plurality of second protrusions 176 may be parallel to each other. It may be arranged.

In addition, the length l1 of the first protrusion 174 and the length l2 of the second protrusion 176 may be the same or different.

Meanwhile, the optical module 140 is inserted into and fixed to the top edge 177 of the first protrusion 174.

5 shows a perspective view of the first protrusion 174A and the optical member 140 according to the embodiment, and FIG. 6 shows a perspective view of the first protrusion 174B and the optical member 140 according to another embodiment.

As shown in FIG. 5, the first protrusion 174A may have a fastening protrusion 178 at the top edge 177. In this case, the optical member 140 is inserted into and fixed to the fastening protrusion 178 through the coupling member 142. Since the shape of the fastening protrusion 178 and the coupling member 142 only needs to be coupled to each other, the shape of the fastening protrusion 178 and the coupling member 142 may be various.

Alternatively, the width w3 of the top edge 177 of the first protrusion 174B may be smaller than the width w4 of the bottom portion of the first protrusion 174B. For example, as shown in FIG. 6, the first protrusion 174B may take the form of gradually widening from the top edge 177 toward the bottom. In this case, the coupling member 142 of the optical member 140 may be inserted into the top edge 177 and fastened without a separate fastening protrusion 178.

The bottom cover 170 having various shapes as described above may be made of a polymer resin such as plastic capable of injection molding.

As such, the backlight unit according to the embodiment fastens the optical member 140 using the first protrusion 174 protruding in the first direction instead of the protruding portion 10 illustrated in FIG. 1. In addition, as shown in FIG. 1, the backlight unit according to the embodiment may protrude in the second direction instead of fastening the bottom cover 70, the top cover 60, and the panel guide module 80 in the vertical direction. 2 The screws 110 are penetrated in the horizontal direction to the first, second and third through holes formed in the protrusion 176, the top cover 160, and the panel guide 180, respectively, and they are fastened to each other. Therefore, compared to the backlight unit illustrated in FIG. 1, the width of the bezel area may be significantly reduced, thereby maximizing the active area of the display panel 190.

According to an embodiment, the width of the bezel area shown in FIG. 2 may be 13 mm to 15 mm, for example, 14 mm.

Hereinafter, a display module having a backlight unit according to an embodiment will be described with reference to the accompanying drawings.

7 illustrates a display module having a backlight unit according to an embodiment.

As shown in FIG. 7, the display module 200 may include a display panel 210 and a backlight unit 220.

The display panel 210 includes a color filter substrate 212 and a thin film transistor (TFT) substrate 214 bonded to face each other so that a uniform cell gap is maintained. The display panel 210 includes two substrates 212 and 214. A liquid crystal layer (not shown) may be interposed therebetween.

The color filter substrate 212 includes a plurality of pixels including red (R), green (G), and blue (B) sub-pixels, and generates light corresponding to the color of red, green, or blue when light is applied. You can.

The pixels may be composed of red, green, and blue subpixels, but the red, green, blue, and white (W) subpixels constitute one pixel, but are not necessarily limited thereto.

The TFT substrate 214 is an element on which switching elements are formed and can switch a pixel electrode (not shown).

For example, the common electrode (not shown) and the pixel electrode may change the arrangement of molecules of the liquid crystal layer according to a predetermined voltage applied from the outside.

The liquid crystal layer is composed of a plurality of liquid crystal molecules, and the liquid crystal molecules change their arrangement corresponding to the voltage difference generated between the pixel electrode and the common electrode.

As a result, the light provided from the backlight unit 220 may be incident on the color filter substrate 212 corresponding to the change in the molecular arrangement of the liquid crystal layer.

In addition, an upper polarizer 216 and a lower polarizer 218 may be disposed on the upper and lower sides of the display panel 210, and more specifically, the upper polarizer 216 is disposed on the upper surface of the color filter substrate 212. The lower polarizer 218 may be disposed on the bottom surface of the TFT substrate 214.

Although not shown, a gate and a data driver for generating a driving signal for driving the display panel 210 may be provided at the side of the display panel 210.

As illustrated in FIG. 7, the display module 200 may be configured by closely placing the backlight unit 220 on the display panel 210.

For example, the backlight unit 220 may be adhered to and fixed to the lower side of the display panel 210, and more particularly, the lower polarizer 218, and between the lower polarizer 218 and the backlight unit 220 for that purpose. An adhesive layer (not shown) may be formed on the substrate.

As such, by forming the backlight unit 220 in close contact with the display panel 210, the overall thickness of the display device may be reduced to improve appearance, and an additional structure for fixing the backlight unit 220 may be removed. The structure and manufacturing process of the display device can be simplified.

In addition, by removing the space between the backlight unit 220 and the display panel 210, it is possible to prevent the malfunction of the display device due to the infiltration of foreign matter into the space or the degradation of the image quality of the display image.

8 and 9 illustrate a display device according to an embodiment.

First, as shown in FIG. 8, the display apparatus 1 is provided in the display module 200, the front cover 300, the back cover 350, and the back cover 350 surrounding the display module 200. It may be composed of a driving unit 550 and a driving unit cover 400 surrounding the driving unit 550.

The front cover 300 may include a front panel (not shown) of a transparent material that transmits light, and the front panel protects the display module 200 at regular intervals, and the light emitted from the display module 200. The light is transmitted through the display module 200 so that the image displayed on the display module 200 is viewed from the outside.

In addition, the front cover 300 may be made of a flat plate without the window 300a.

In this case, the front cover 300 may be made of a transparent material that transmits light, for example, injection molded plastic.

As such, when the front cover 300 is formed of a flat plate, the frame can be removed from the front cover 300.

The back cover 350 may be combined with the front cover 300 to protect the display module 200.

The driving unit 550 may be disposed on one surface of the back cover 350.

The driver 550 may include a drive controller 550a, a main board 550b, and a power supply unit 550c.

The driving control unit 550a may be a timing controller. The driving control unit 550a may be a driving unit for adjusting an operation timing of each driver IC of the display module 200. And a driving unit for transmitting G and B resolution signals, and the power supply unit 550c may be a driving unit for applying power to the display module 200.

The driver 550 may be provided in the back cover 350 and may be wrapped by the driver cover 400.

A plurality of holes may be provided in the back cover 350 to connect the display module 200 and the driver 550, and a stand 600 supporting the display apparatus 1 may be provided.

Subsequently, as shown in FIG. 9, the driving controller 550a of the driving unit 550 may be provided in the back cover 350, and the main board 550b and the power board 550c may be provided in the stand 600. have.

In addition, the driver cover 400 may wrap only the driver 550 provided in the back cover 350.

In an embodiment, the main board 550b and the power board 550c are separately configured, but may be formed as one integrated board, but the present invention is not limited thereto.

In addition, the lighting apparatus according to the embodiment may include a backlight unit. Here, the lighting device may further include a display panel that receives light from the backlight unit.

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments 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: display device 6: screw
10: protrusion 20, 120: light guide plate
30, 130: reflector 40, 140: optical member
50, 150: light source modules 52, 152: substrate
54, 154: light source 60, 160: top chassis
70, 170: bottom chassis 80: panel guide module
162: third through hole 171: first side
172: bottom surface 174: first protrusion
175: first through hole 176: second protrusion
177: top edge 178: fastening protrusions
179: second side 180: panel guide portion
182: second through hole 200: display module
210: display panel 212, 214: substrate
216: upper polarizer 218: lower polarizer
220: backlight unit 300: front cover
350: back cover 400: drive part cover
550: drive unit 550a: drive control unit
550b: Motherboard 550c: Power Supply
600: stand

Claims (20)

A bottom surface, a first protrusion extending and protruding from the bottom surface in a first direction about a first side of the bottom surface, and the bottom surface in a second direction different from the first direction around the first side; A bottom cover extending from the bottom and having a second protrusion having a first through hole formed therein;
A panel guide portion having a second through hole;
A top cover having a third through hole;
A fastening member penetrating the first, second and third through holes to fasten the bottom cover, the panel guide part and the top cover; And
And an optical module inserted into and fixed to the top edge of the first protrusion. The method of claim 1, wherein the bottom surface further has at least one second side different from the first side,
The first protrusion protrudes from the bottom surface in the first direction about the second side, and the second protrusion protrudes from the bottom surface in the second direction about the second side. And the first through hole is formed. The backlight unit of claim 1, wherein the first direction and the second direction are opposite to each other. The backlight unit of claim 1, wherein a thickness of the first protrusion is different from a thickness of the second protrusion. The backlight unit of claim 1, wherein a thickness of the first protrusion and a thickness of the second protrusion are the same. The backlight unit of claim 1, wherein a thickness of the first protrusion is different from a thickness of the bottom surface. The backlight unit of claim 1, wherein a thickness of the second protrusion is different from a thickness of the bottom surface. The backlight unit of claim 1, wherein a thickness of the first protrusion, a thickness of the second protrusion, and a thickness of the bottom surface are the same. The backlight unit of claim 1 or 2, wherein the first protrusion and the second protrusion are alternately formed to extend from the bottom surface. The backlight unit of claim 1, wherein the first protrusion and the second protrusion extend from the bottom surface on the same straight line. The backlight unit of claim 1, wherein a width of the first protrusion and a width of the second protrusion are the same. The backlight unit of claim 1, wherein the width of the first protrusion and the width of the second protrusion are different from each other. The backlight unit of claim 1, wherein the first protrusion has a fastening protrusion at the top edge, and the optical member is inserted into and fixed to the fastening protrusion. The backlight unit of claim 1, wherein the fastening member is a screw. The backlight unit of claim 1, wherein a width of the top edge of the first protrusion is less than a width of the bottom of the first protrusion. The backlight unit of claim 15, wherein the first protrusion extends toward the bottom from the top edge. The backlight unit of claim 1, wherein the first protrusion is plural and the second protrusion is plural. The backlight unit of claim 17, wherein the plurality of first protrusions and the plurality of second protrusions are alternately disposed. An illumination device comprising the backlight unit of claim 1. The method of claim 19,
And a display panel that receives light from the backlight unit.

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