KR20130031437A - Backlight unit and display device including the same - Google Patents

Abstract

PURPOSE: A backlight unit and a display device including the same are provided to stably arrange an optical sheet. CONSTITUTION: A reflecting plate(220) is arranged on a bottom cover(210). A light emitting device package(300) is arranged in the reflecting plate. Each optical sheet(230,240,250,260) has a hole. A connecting part(223) of the reflecting plate is inserted into the hole. The reflecting plate is arranged between the light emitting device packages.

Description

Backlight unit and display device including the same {Backlight unit and display device including the same}

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

Typically, typical large-sized display devices include a liquid crystal display (LCD), a plasma display panel (PDP), and the like.

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

The backlight unit used in the LCD is divided into an edge type backlight unit and a direct-type backlight unit according to the position of the light source. In the edge type, a light source is disposed on the right and left sides or upper and lower sides of the LCD panel, Since the light is uniformly distributed over the surface, uniformity of light is good and the thickness of the panel can be made very thin.

CCFL (Cold Cathode Fluorescent Lamp) is used as the light source of the backlight unit of the conventional edge type or direct type.

However, since the CCFL-based backlight unit is always powered by the CCFL, a considerable amount of power is consumed, and the problems of environmental pollution due to the addition of about 70% color reproduction rate and mercury are pointed out as disadvantages.

As a substitute for solving the above problems, research on a backlight unit using an LED (Light Emitting Diode) 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. For the RGB LED, it exceeds 100% of the NTSC (National Television System Committee) color reproduction range specification. To provide consumers with more vivid picture quality.

In addition, the LED produced by the semiconductor process is characterized by harmless to the environment.

LCD products employing LEDs with the above advantages are being released one after another. However, since the driving mechanism is different from the existing CCFL light source, driving drivers and PCB substrates are expensive.

Therefore, the LED backlight unit is still applied only to expensive LCD products.

1 is an exploded perspective view of a display device including an edge type backlight unit.

The display device 100 includes a light source module, a reflector 120 on the bottom cover 110, and a light guide plate 140 disposed in front of the reflector 120 and guiding light emitted from the light source module to the front of the display device. And a first prism sheet 150 and a second prism sheet 160 disposed in front of the light guide plate 140, a panel 170 disposed in front of the second prism sheet 160, and the panel ( It comprises a color filter 180 disposed in the first half of the 170.

The edge type backlight unit uses the light guide plate 130 to scatter light emitted from the light emitting device package 135 disposed on the side surface so that the light is uniformly distributed over the entire screen of the liquid crystal display.

The light guide plate 130 scatters the light emitted from the light emitting device package 135 so that the light is uniformly transmitted. Therefore, the light guide plate 130 is made of a material having a good refractive index and transmittance, and is formed of polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), or the like. 130) may increase weight and increase manufacturing costs.

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

The backlight unit of the direct type may not use a light guide plate, but especially in the case of using a light source that emits light at a specific angle and direction, such as an LED, a bright part and a dark part are formed according to a position where the light source is disposed, Uniformity may be degraded. In particular, when the number of light sources is reduced by using high power LEDs, the above-described dark portions may be formed between the respective LEDs.

In addition, in the edge type backlight unit, the optical sheet is fixed on the light guide plate, but in the direct type backlight unit, fixing of the optical sheet may be problematic because the optical sheet is disposed at a predetermined distance from the light source.

Embodiments provide a backlight unit in which brightness is improved and an optical sheet is stably disposed.

Embodiments include a bottom cover; An array of light emitting device packages disposed on the bottom cover in columns and rows; A reflector disposed on the bottom cover; And an optical sheet for transmitting light emitted from the light emitting device package array, at least one of the reflecting plates is formed with a fastening portion, a hole is formed in the optical sheet, and the holes of the optical sheet are fastening portions of the reflecting plate. It provides a backlight unit that is inserted into.

The reflector may include a bottom surface and sidewalls that form an obtuse angle with the bottom surface.

The side wall of the reflector may have a length different in the horizontal direction and a length in the vertical direction.

Sidewalls of the reflector may have different inclinations in the horizontal direction and in the vertical direction.

The backlight unit may further include a lens disposed inside the reflector and surrounding the light emitting device package.

The height of the reflector can be 15 to 25 millimeters.

The reflector may be made of tempered glass.

The fastening part may be disposed above the sidewall of the reflector.

The fastening portion may have a circular cross section.

An open area may be formed on a bottom surface of the reflector, and the light emitting device package may contact the bottom cover in the open area.

The side surface of the light emitting device package may contact the reflecting plate, and the bottom surface of the light emitting device package may contact the bottom cover.

A pattern may be formed on the surface of the reflecting plate.

The reflector may further include a support part for supporting the optical sheet.

Another embodiment provides a display device including the backlight unit described above.

In the backlight unit and the display device according to the embodiment, the light extraction efficiency is improved, so that a small number of light emitting device packages can be used. You may not use the supporter.

1 is an exploded perspective view of a display device including an edge type backlight unit;
2 is a cross-sectional view of the backlight unit of the direct type;
3A and 3B are views illustrating a reflector plate and a light emitting device package of the backlight unit of FIG. 2;
4 is a view showing an embodiment of a light emitting device package of the backlight unit of FIG.
5A to 5F are enlarged views of one embodiment of 'A' of FIG. 2,
6 is an enlarged view of a portion of the reflector of FIG. 5A,
7 is a cross-sectional view in a horizontal direction and a vertical direction of the reflector of FIG. 5A,
FIG. 8 is a perspective view of the diffusion sheet of FIG. 5A, and FIGS. 9A to 9D are enlarged views of other embodiments of 'A' of FIG. 2,
10A and 10B are enlarged views of still other embodiments of 'A' of FIG. 2,
11A and 11B are enlarged views of still other embodiments of 'A' of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, when described as being formed on the "on or under" of each element, the (up) or down (on) or under) includes both two elements being directly contacted with each other or one or more other elements are formed indirectly between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. In addition, the size of each component does not necessarily reflect the actual size.

2 is a cross-sectional view of the backlight unit of the direct type.

The backlight unit 200 of the direct method is disposed a plurality of light sources for emitting light, the light emitting device package 300 array may be used as the light source.

On the bottom surface of the light emitting device package 300 array, a reflector 220 is disposed to transmit light emitted from the light emitting device package 300 in an upper direction, that is, in a direction of an optical sheet. In addition, the bottom cover 210 may be disposed to support the bottom surface of the reflective plate 220, and the optical sheets 230, 240, 250, and 260 may be supported and disposed at the edge of the bottom cover 210.

3A and 3B illustrate a reflector plate and a light emitting device package of the backlight unit of FIG. 2.

As shown, the array of light emitting device packages 300 may be arranged in columns and rows, for example, in a matrix form, on the bottom cover 210 or the reflector plate 220. The light emitting device package 300 array may be arranged side by side in the column and row direction as shown in FIG. 3B or alternately in the column and / or row direction as shown in FIG. 3A. The reflecting plate 220 is disposed around the light emitting device package 300, and may be disposed around each light emitting device package 300 or may be disposed around the bottom and the bottom surface of the light emitting device package 300. Examples will be described later.

Although the edges of the above-described optical sheets 230, 240, 250, and 260 are supported by the bottom cover 210, support of the center region is a problem, and if a separate supporter is placed, manufacturing costs and processes increase. The progress of the light emitted from the light emitting device package 300 in the supporter may be a problem.

In the above-described backlight unit 200, a fastening part is formed in at least one of the reflecting plates 220, a hole corresponding to the fastening part is formed in the optical sheet, and the fastening part of the reflecting plate 220 is inserted into the hole of the optical sheet. This can be explained below.

4 is a diagram illustrating an embodiment of a light emitting device package of the backlight unit of FIG. 2. Hereinafter, the structure of the light emitting device package will be described in detail with reference to FIG. 4.

The light emitting device package 300 according to the embodiment may be installed in the package body 310, the first lead frame 321 and the second lead frame 322 installed in the package body 310, and the package body 310. The light emitting device 360 is electrically connected to the first lead frame 321 and the second lead frame 322, and a molding part 350 surrounding the surface or the side surface of the light emitting device 360.

The package body 310 may include a polyphthalamide (PPA) resin, a silicon material, a synthetic resin material, or a metal material. An inclined surface may be formed around the light emitting device 360 to increase light extraction efficiency.

The first lead frame 321 and the second lead frame 322 are electrically separated from each other, and provide power to the light emitting device 360. In addition, the first lead frame 321 and the second lead frame 322 may increase the light efficiency by reflecting the light generated from the light emitting device 360, the heat generated by the light emitting device 360 It may also play a role in discharging it to the outside.

The light emitting device 360 may be installed on the package body 310 or on the first lead frame 321 or the second lead frame 322. The light emitting device 360 may be electrically connected to the first lead frame 321 and the second lead frame 322 by any one of a wire method, a flip chip method, or a die bonding method. In the present exemplary embodiment, the light emitting device 360 is connected to the first lead frame 321 and the conductive adhesive layer 330 and is bonded to the second lead frame 322 and the wire 340.

The molding part 350 may surround and protect the light emitting device 360. In addition, the molding part 350 may include a phosphor 355 to change the wavelength of the light emitted from the light emitting device 360.

A plurality of light emitting device packages 300 according to the embodiment may be arranged on the reflecting plate 220 on the bottom cover 210, and an optical member may be disposed on the light path of the light emitting device package. The light emitting device package 300, the bottom cover 210, and the optical members 230, 240, 250, and 260 may function as a backlight unit.

The reflective plate 220 may use a material having high reflectance and being extremely thin, and may use tempered glass or polyethylene terephtalate (PET). The reflecting plate 220 may be formed of silver (Ag) or aluminum (Al) having excellent reflectivity on the surface of the bottom cover 210 or an alloy thereof.

The bottom cover 210 may accommodate components such as the light emitting device package 300 or the reflecting plate 220, the bottom surface 210a may support the light emitting device package 300, and the sidewall 210b may have a step difference. In order to support the optical sheet, the side wall 210b may be disposed perpendicularly to the bottom surface 210a without necessarily inclining.

The optical sheet may include a diffusion sheet 230, a first fried sheet 240, a second prism sheet 250, and a protective sheet 260, and the arrangement order of each sheet may be changed. The optical sheets 230, 240, 250, and 260 may further include various sheets in addition thereto, and the order thereof is not limited thereto.

The diffusion sheet 230 may be made of a polyester and polycarbonate-based material, and may widen the light projection angle by refracting and scattering light incident from the light emitting device package 300 array.

The first prism sheet 240 is formed of a light transmitting and elastic polymer material on one surface of the support film, and the polymer may have a prism layer in which a plurality of three-dimensional structures are repeatedly formed. The first prism sheet 240 may have a floor and a valley repeatedly formed in a stripe type to form a pattern.

The direction of the floor and the valley in the second prism sheet 250 is disposed perpendicular to the direction of the floor and the valley of one surface of the supporting film in the first prism sheet 240, and thus, The transmitted light can be evenly distributed in all directions of the panel.

5A to 5F are enlarged views of one embodiment of 'A' of FIG. 2.

The reflector 220 is disposed on the bottom cover 210, and one light emitting device package 300 is disposed on each reflector 220. The reflector plate 220 may include a bottom surface 221, a sidewall 222, and a fastening part 223 formed on the sidewall 222.

Holes are formed in each of the optical sheets 230, 240, 250, and 260, and the fastening portion 223 of the reflector plate 220 is inserted into the holes of the optical sheets 230, 240, 250, and 260 to insert the holes. 230, 240, 250, and 260 may be fixed and supported.

Light emitted from each light emitting device package 300 is reflected from the surface of the reflector 220 to travel in the direction of the optical sheets 230, 240, 250, and 260, and the optical sheets 230, 240, 250 and 260 are holes. Since it is fixed through the fastening part 223, the light transmission of the entire backlight unit can be made stable.

In the present embodiment, the light emitting device packages 300 are disposed on the bottom surface 221 of the reflecting plate 220, but in the embodiment illustrated in FIG. 5B, the light emitting device packages 300 contact the bottom cover 210. The reflection plate 220 is disposed and includes a sidewall 222 and a fastening part 223.

In the embodiment shown in FIG. 5C, the reflector plate 220 includes a bottom surface 221 in addition to the sidewall 222 and the fastening portion 223, but an open area is formed on the bottom surface 221, and The light emitting device package 300 may be disposed in contact with the bottom cover 210.

The embodiment shown in FIG. 5D is similar to the embodiment shown in FIG. 5A, but the pattern 225 is formed on the bottom surface 221 of the reflective plate 220 and the surface of the side wall 222. The pattern 225 is formed of the same material or different material as the reflective plate 220 in a regular or irregular pattern, and the light emitted from the light emitting device package 300 is scattered in the pattern 225, the optical sheet 230, 240. 250. 260) to proceed evenly over the entire area.

5E is similar to the embodiment shown in FIG. 5A, except that the lens 270 is formed inside the reflector 220. The lens 270 is made of a light-transmissive material, and the path of the light emitted from the light emitting device package 300 may be refracted at the interface of the lens 270.

In the embodiment illustrated in FIG. 5F, one optical sheet 230 is inserted into the fastening portion 223 of the reflecting plate 220, and the other three optical sheets 240, 250, and 260 are connected to the fastening portion 223. It is disposed on the optical sheet 230. That is, a groove is formed in at least one of the optical sheets 230, 240, 250, and 260, and a fastening part 223 is inserted into the groove, and the remaining optical sheets 230, 240, 250, and 260 are fastening parts 223. FIG. 6 is an enlarged view of a portion of the reflector of FIG. 5A, FIG. 7 is a cross-sectional view in the horizontal and vertical directions of the reflector of FIG. 5A, and FIG. 8 is a perspective view of the diffusion sheet of FIG. 5A. .

The side wall 222 of the reflector plate 220 may have a conical shape, and the fastening part 223 may be disposed on the upper portion of the body 222. The fastening part 223 may have a cylindrical shape and a horizontal cross section may have a circular shape. The height h ₂ of the fastening part 223 may be 2 to 4 millimeters, and the optical sheets 230, 240, 250, and 260 may be formed. It may be a thickness that all the holes are inserted.

The diameter (w) of the fastening part 223 may be 1 to 10 millimeters, and should be smaller or smaller than the size of the hole formed in the optical sheets 230, 240, 250, and 260 so that the fastening part 223 may be inserted into the hole. Can be.

7 shows the size and the slope of the side wall of the reflector.

The distance between the side wall and the adjacent side wall in the reflecting plate is 90 to 110 millimeters in the horizontal axis direction and 80 to 100 millimeters in the longitudinal axis direction. Typically, the display device has a longer length in the horizontal axis direction, and the reflecting plates are far from each other in the horizontal axis direction.

In FIG. 7, an angle θ ₂ between the bottom surface and the sidewall of the reflector in the longitudinal axis b may be greater than an angle θ ₁ between the bottom surface and the sidewall of the reflector in the horizontal axis direction a. The height of the sidewalls of is equal to 15 to 25 millimeters because the distance between the sidewalls is closer in the longitudinal axis direction (b).

In FIG. 8, the diffusion sheet 230 includes a body 230a and a hole 230b, in which the fastening portion 223 of the reflective plate 220 may be inserted, and another optical sheet 240 may be inserted therein. The same through hole may be formed at a position corresponding to the positions 250 and 260 as well.

In the backlight unit having the above-described structure, since a reflector is disposed around each light emitting device package, light extraction efficiency is improved, and thus the luminance may be improved even if a smaller number of light emitting device packages are used than in the related art. For example, it is possible to implement the same luminance even if one high output light emitting device package is used in place of the four light emitting device packages used in the related art. Then, the fastening portion formed in the reflecting plate is inserted into the groove of the optical sheet, thereby stably disposing the optical sheet, and a separate supporter may not be used.

9A-9D are enlarged views of other embodiments of 'A' of FIG. 2.

In the embodiment illustrated in FIG. 9A, the reflective plate 220 includes only the bottom surface 221 and the sidewall 222, and the upper side of the sidewall 222 may serve as a fastening portion. In addition, since the side wall 222 is narrower as it moves away from the bottom surface 221, the diameter or size of the hole formed in the optical sheets 230, 240, 250, and 260 fastened to the side wall 222 may also be reduced. Away from 222).

The embodiment shown in FIG. 9B is similar to the embodiment shown in FIG. 9A, but the light emitting device package 300 is disposed in contact with the bottom cover 210, and the reflector plate 220 includes sidewalls 222.

In the embodiment illustrated in FIG. 9C, the reflective plate 220 includes a sidewall 222 and a bottom surface 221, but an open area is formed on the bottom surface 221, and the light emitting device package 300 is formed in the open area. May be disposed in contact with the bottom cover 210.

The embodiment shown in FIG. 9D is similar to the embodiment shown in FIG. 9A, but the pattern 225 is formed on the bottom surface 221 of the reflective plate 220 and the surface of the side wall 222. The pattern 225 is formed of the same material or different material as the reflective plate 220 in a regular or irregular pattern, and the light emitted from the light emitting device package 300 is scattered in the pattern 225, the optical sheet 230, 240. 250. 260) to proceed evenly over the entire area.

10A and 10B are enlarged views of still other embodiments of 'A' of FIG. 2.

In the embodiment shown in FIG. 10A, the reflector plate 220 has a vertical portion 224 in contact with the bottom cover 210, a sidewall 222 extending from the vertical portion 224, and an upper portion of the sidewall 222. It includes a fastening portion 223 formed.

The side surface of the light emitting device package 300 is in contact with the vertical portion 224 of the reflective plate 220, the bottom surface is in contact with the bottom cover 300. If the distance between the vertical portions 224 of the reflector 220 is equal to the width of the light emitting device package 300, the vertical portions 224 may fix the light emitting device package 300.

The embodiment shown in FIG. 10B is similar to the embodiment shown in FIG. 10A, but the pattern 225 is formed on the surface of the sidewall 222 of the reflector plate 220.

11A and 11B are enlarged views of still other embodiments of 'A' of FIG. 2.

5B are similar to the embodiment shown in FIG. 5B, but two kinds of reflecting plates 220a and 220b are disposed between the respective light emitting device packages 300. The reflecting plate 220a is the same as the reflecting plate 220 shown in FIG. 5B and includes a sidewall 222a and a fastening part 223a, and the fastening part 223a is formed of the optical sheets 230, 240, 250, and 260. Can be fixed.

Since the fastening part 223a fixes the optical sheet, it is not necessary to arrange all of the reflecting plates around the respective light emitting device packages 300, and the number of fastening parts 223a may be arranged to fix the optical sheet and prevent sagging. The reflective plate 220a having the fastening part 223a may be disposed in one to several parts according to the size of the panel in which the backlight unit is to be used.

In addition, the reflecting plate 220b in which the fastening part is not disposed is formed of the side wall 222b and the support part 223b, and the support part 223b may be supported only without being fastened with the optical sheets 230, 240, 250, and 260. .

The embodiment shown in FIG. 11B is similar to the embodiment of FIG. 11A, except that the reflective plate 220b in which the fastening part is not disposed is formed only of sidewalls. That is, in FIG. 11A, at least one of the optical sheets 230, 240, 250, and 260 is in surface contact with the support part 220b. In FIG. 11B, at least one of the optical sheets 230, 240, 250, and 260 is supported by the support part 220b. ) Can be in line contact.

A panel (not shown) may be disposed in the backlight unit 200 of FIG. 2 to form an image display device. A liquid crystal display panel may be disposed as the panel. In addition to the liquid crystal display panel, other types of display devices requiring a light source may be provided.

The panel is in a state in which a liquid crystal is positioned between a pair of transparent substrates and a polarizing plate is placed on each transparent substrate in order to use polarization of light. Here, the liquid crystal has an intermediate property between a liquid and a solid, and liquid crystals, which are organic molecules having fluidity like a liquid, are regularly arranged like crystals. The liquid crystal has a structure in which the molecular arrangement is changed by an external electric field And displays an image.

A liquid crystal display panel used in a display device is an active matrix type, and a transistor is used as a switch for controlling a voltage supplied to each pixel.

The front surface of the panel is provided with a color filter to transmit the light projected by the panel, only the red, green and blue light for each pixel can represent the image.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications 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.

100: display device 110, 210: bottom cover
120, 220, 220a, 220b: reflector
130: circuit board module 140: light guide plate
150, 160: first and second prism sheet 170: panel
180: color filter 200: backlight unit
221: bottom surface 222, 222a, 222b: side wall
223b: support portion
223, 223a: fastening portion 224: vertical portion
230, 240, 250, 260: Optical sheet 230a: Body
230b: hole 300: light emitting device package
310: package body 321, 322: first and second lead frame
330: conductive adhesive layer 340: wire
350 molding unit 355 phosphor
360: light emitting element

Claims (21)

Bottom cover;
An array of light emitting device packages disposed on the bottom cover in columns and rows;
A reflector disposed on the bottom cover; And
It includes an optical sheet for transmitting the light emitted from the light emitting device package array,
At least one of the reflecting plate is formed with a fastening portion, the optical sheet is a hole is formed, the backlight unit is inserted into the fastening portion of the reflecting plate. The method of claim 1,
The reflector is a backlight unit disposed between the light emitting device package. The method of claim 2,
The reflector includes a bottom surface and a side wall making an obtuse angle with the bottom surface. The method of claim 1,
The side wall of the reflector is a backlight unit having a length different in the horizontal direction and the length in the vertical direction. The method of claim 1,
The side wall of the reflector is a backlight unit having a different inclination in the horizontal direction and the vertical direction. The method of claim 1,
At least a portion of the side wall of the reflecting plate is a conical shape of the backlight unit. The method of claim 1,
The reflector is a backlight unit consisting of only the side wall. The method of claim 1,
The backlight unit further comprises a lens disposed inside the reflector and surrounding the light emitting device package. The method of claim 1,
And a height of the reflector is 15 to 25 millimeters. The method of claim 1,
The reflector is a backlight unit made of tempered glass. The method of claim 1,
The fastening unit is a backlight unit disposed on the sidewall of the reflector. The method of claim 1,
The fastening unit has a circular cross section. The method of claim 1,
An open area is formed on a bottom surface of the reflector, and the light emitting device package contacts the bottom cover in the open area. The method of claim 13,
And a side surface of the light emitting device package contacts the reflecting plate, and a bottom surface of the light emitting device package contacts the bottom cover. The method of claim 1,
The backlight unit further comprises irregularities formed on the surface of the reflecting plate. The method of claim 1,
The reflector further comprises a support unit for supporting the optical sheet. 17. The method of claim 16,
At least one of the optical sheets is in surface contact with the support part. 17. The method of claim 16,
At least one of the optical sheets is in line contact with the support. The method of claim 1,
Each of the light emitting device packages may be disposed side by side in at least one of column and row directions. The method of claim 1,
Each of the light emitting device packages may be alternately arranged in at least one of column and row directions. A display device comprising the backlight unit of claim 1.

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