KR101830720B1 - Backlight unit and display device including the same - Google Patents

Abstract

An embodiment includes a bottom cover; A light emitting device package array arranged in rows and columns on the bottom cover; A reflector disposed on the bottom cover; And an optical sheet for transmitting light emitted from the light emitting device package array, wherein at least one of the reflection plates has a fastening portion, a hole is formed in the optical sheet, In the backlight unit.

Description

BACKLIGHT UNIT AND DISPLAY DEVICE COMPRISING THE SAME

The embodiment relates 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 a self-luminous PDP, a backlight unit is indispensable because of 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 backlight unit using CCFL is always supplied with power to the CCFL, a considerable amount of power is consumed, and a color reproduction ratio of about 70% as compared with CRT and environmental pollution problems caused by the addition of mercury are pointed out as disadvantages.

BACKGROUND ART [0002] As a substitute product for solving the above problem, researches on a backlight unit using an LED (Light Emitting Diode) have been actively conducted.

When the LED is used as a backlight unit, it is possible to partially turn on / off the LED array, thereby drastically reducing the power consumption. In the case of the RGB LED, the color reproduction range specification exceeding 100% of the National Television System Committee (NTSC) So that a more vivid image quality can be provided to the consumer.

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

Currently, LCD products employing LEDs having the above advantages are being marketed extensively. However, since the conventional CCFL light source is different from the driving mechanism, driving drivers and PCB substrates are expensive.

Therefore, the LED backlight unit is only applied 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 reflection plate 120 on the bottom cover 110, a light guide plate 140 disposed in front of the reflection plate 120 and guiding light emitted from the light source module toward the front of the display device, 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 a color filter 180 disposed in the first half of the color filter 180.

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 and uniformly distribute the light over the whole screen area of the LCD.

The light guide plate 130 scatters the light emitted from the light emitting device package 135 to uniformly transmit the light. Accordingly, the light guide plate 130 is made of a material having a good refractive index and transmittance. The light guide plate 130 is formed of a material such as polymethyl methacrylate (PMMA), polycarbonate (PC), or polyethylene (PE) 130), the weight may increase and the manufacturing cost may increase.

The direct type is usually used for displays of 20 inches or more, and since the light sources are arranged at a lower portion of the panel, the light efficiency is higher than that of the edge type, which is mainly used for large displays requiring high brightness.

A direct-type backlight unit may not use a light guide plate, but in particular, when a light source that emits light in a certain angle and direction, such as an LED, is used, a light portion and a dark portion are formed depending on the position where the light source is disposed, The uniformity may be lowered. In particular, when the number of light sources is reduced by using a high-output LED, the above-described dark portions may be formed between the respective LEDs.

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

The embodiment intends to provide a backlight unit in which brightness is improved and an optical sheet is stably disposed.

An embodiment includes a bottom cover; A light emitting device package array arranged in rows and columns on the bottom cover; A reflector disposed on the bottom cover; And an optical sheet for transmitting light emitted from the light emitting device package array, wherein at least one of the reflection plates has a fastening portion, a hole is formed in the optical sheet, In the backlight unit.

The reflector may include a bottom surface and side walls that are at an obtuse angle with the bottom surface.

The side walls of the reflector may have different lengths in the horizontal direction and the vertical direction.

The sidewall of the reflection plate may have a slope in the horizontal direction and a slope in the vertical direction.

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

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

The reflector may be made of tempered glass.

The fastening portion may be disposed on an upper portion of the side wall of the reflection plate.

The fastening portion may be circular in cross section.

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

The side surface of the light emitting device package may be in contact with the reflective plate, and the bottom surface of the light emitting device package may be in contact with the bottom cover.

A pattern may be formed on the surface of the reflector.

The reflection plate may further include a support for supporting the optical sheet.

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

The backlight unit and the display device according to the embodiments can improve the light extraction efficiency and use a small number of light emitting device packages. The optical fiber sheet can be stably arranged by inserting the fastening portions formed on the reflector into the grooves of the optical sheet, The supporter of the present invention may not be used.

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

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, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed 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. Also, the size of each component does not entirely reflect the actual size.

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

The direct-type backlight unit 200 includes a plurality of light sources that emit light, and an array of the light emitting device packages 300 may be used as a light source.

A reflection plate 220 for transmitting light emitted from the light emitting device package 300 to the upper direction, that is, the direction of the optical sheet, is disposed on the bottom surface of the array of the light emitting device package 300. The bottom cover 210 supports and arranges the bottom surface of the reflector 220 and the optical sheets 230, 240, 250 and 260 are supported and disposed at the edge of the bottom cover 210.

3A and 3B are views showing a reflection plate and a light emitting device package of the backlight unit of FIG.

As shown, the array of light emitting device packages 300 may be arranged in rows and columns, for example, in the form of a matrix, on the bottom cover 210 or the reflector 220. The array of the light emitting device packages 300 may be arranged as shown in FIG. 3B in parallel with the row and row directions, or may be arranged as shown in FIG. 3A as being staggered in the row and / or row directions. The reflector 220 is disposed around the light emitting device package 300 and may be disposed around the light emitting device package 300 or on the periphery and the bottom surface of the light emitting device package 300, This will be described later in Examples.

Although the edges of the optical sheets 230, 240, 250 and 260 are supported by the bottom cover 210, there is a problem in supporting the middle region, and disposing a separate supporter increases manufacturing cost and process , The progress of light emitted from the light emitting device package 300 in the supporter may be a problem.

In the backlight unit 200 described above, at least one of the reflection plates 220 is formed with a fastening portion, a hole corresponding to the fastening portion is formed on the optical sheet, and the fastening portion of the reflection plate 220 is inserted into the hole of the optical sheet Which will be described below.

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

The light emitting device package 300 according to the embodiment includes a package body 310, a first lead frame 321 and a second lead frame 322 provided on the package body 310, A light emitting device 360 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. The 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. 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 and the heat generated from the light emitting device 360 To the outside.

The light emitting device 360 may be mounted on the package body 310 or may be mounted 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 a wire, flip chip, or die bonding method. In this embodiment, the light emitting device 360 is connected to the first lead frame 321 through the conductive adhesive layer 330, and the second lead frame 322 and the wires 340 are bonded.

The molding part 350 surrounds and protects 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 reflector 220 on the bottom cover 210 and an optical member may be disposed on the optical 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 can be made of a material having a high reflectance and can be used in an ultra-thin shape, and can be made of tempered glass or PolyEthylene Terephtalate (PET). The reflector 220 may be formed of silver (Ag), aluminum (Al), or an alloy thereof coated on the surface of the bottom cover 210 with high reflectance.

The bottom cover 210 can accommodate components such as the light emitting device package 300 and the reflection plate 220. The bottom surface 210a can support the light emitting device package 300 and the side walls 210b can support the light emitting device package 300, The side wall 210b may not necessarily be inclined and may be disposed perpendicular to the bottom surface 210a.

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

The diffusion sheet 230 may be made of polyester and polycarbonate-based materials, and the light incidence angle may be maximized by refracting and scattering light incident from the array of light emitting device packages 300.

The first prism sheet 240 is formed on one side of the support film with a transparent and elastic polymeric material, and the polymer may have a prism layer in which a plurality of steric structures are repeatedly formed. In the first prism sheet 240, a floor and a valley may be repeatedly provided in a stripe pattern to form a pattern.

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

5A-5F are enlarged views of one embodiment of 'A' in FIG.

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

Holes are formed in the respective optical sheets 230, 240, 250 and 260 and the coupling parts 223 of the reflection plate 220 are inserted into the holes of the optical sheets 230, 240, 250 and 260, (230, 240, 250, 260) can be fixed and supported.

The light emitted from each light emitting device package 300 is reflected from the surface of the reflection plate 220 and travels in the direction of the optical sheets 230, 240, 250, and 260 and the optical sheets 230, 240, 250, And the coupling portion 223, so that the light transmission of the entire backlight unit can be stably performed.

The light emitting device package 300 is disposed on the bottom surface 221 of the reflector 220 in the present embodiment, but in the embodiment shown in FIG. 5B, the light emitting device package 300 is in contact with the bottom cover 210 And the reflector 220 is composed of a side wall 222 and a fastening portion 223.

5c, the reflection plate 220 includes a bottom surface 221 in addition to the side wall 222 and the coupling portion 223, but an open region is formed in the bottom surface 221, 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 a pattern 225 is formed on the bottom surface 221 of the reflector 220 and the surface of the side wall 222. The pattern 225 is formed in the regular or irregular pattern of the same material or other materials as the reflector 220 and the light emitted from the light emitting device package 300 is scattered in the pattern 225 to form the optical sheets 230, 240, 250, and 260, respectively.

The embodiment shown in FIG. 5E is similar to the embodiment shown in FIG. 5A, except that a lens 270 is formed inside the reflection plate 220. FIG. The lens 270 may be 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.

5f, one optical sheet 230 is inserted into the coupling part 223 of the reflection plate 220 and the other three optical sheets 240, 250 and 260 are inserted into the coupling part 223 And is disposed on the optical sheet 230. That is, at least one of the optical sheets 230, 240, 250, and 260 has grooves formed therein, the coupling portions 223 are inserted into the grooves, and the remaining optical sheets 230, 240, 250, FIG. 6 is an enlarged view of a part of the reflection plate of FIG. 5A, FIG. 7 is a cross-sectional view of the reflection plate of FIG. 5A in the lateral direction and the longitudinal direction, and FIG. 8 is a perspective view of the diffusion sheet of FIG. .

The side wall 222 of the reflector 220 may have a conical shape and a fastening portion 223 may be disposed on the upper portion of the body 222. The fastening portion 223 may have a cylindrical shape and a horizontal cross section may have a circular shape and the height h ₂ of the fastening portion 223 may be 2 to 4 millimeters. It may be a thickness at which the holes are all inserted.

The coupling portion 223 may have a diameter w of 1 to 10 millimeters and may be smaller or smaller than the hole formed in the optical sheets 230, 240, 250 and 260 so that the coupling portion 223 is inserted into the hole .

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

The distance between the side walls and the adjacent side walls in the reflector is 90 to 110 millimeters in the transverse direction and 80 to 100 millimeters in the longitudinal direction. Typically, the length of the display device in the horizontal direction is longer, and the reflection plate is also distant from each other in the horizontal direction.

The angle θ ₂ between the bottom surface and the side wall of the reflector in the longitudinal axis direction may be larger than the angle θ ₁ formed by the bottom surface and the side wall of the reflector in the horizontal axis direction a in FIG. The height of the sidewalls is equal to 15 to 25 millimeters because the distance between the side walls is closer in the vertical axis direction (b).

8, the diffusion sheet 230 includes a body 230a and a hole 230b. The hole 230b may be formed by inserting the coupling portion 223 of the reflection plate 220 and the other optical sheet 240 , 250, and 260, respectively.

In the backlight unit having the above-described structure, since a reflection plate is disposed in the periphery of each light emitting device package, the light extraction efficiency is improved, so that the brightness can be improved even when a smaller number of light emitting device packages than the conventional ones are used. For example, the same luminance can be achieved by replacing the conventional four light emitting device packages and using one high output light emitting device package. Then, the fastening portion formed on the reflection plate is inserted into the groove of the optical sheet, the optical sheet is stably placed, and no separate supporter is used.

9A to 9D are enlarged views of other embodiments of 'A' in FIG.

In the embodiment shown in FIG. 9A, the reflector 220 is composed only of the bottom surface 221 and the side wall 222, with the top of the side wall 222 acting as a fastening. The diameter or the size of the holes formed in the optical sheets 230, 240, 250, 260 fastened to the side walls 222 may be smaller than the diameter or the size of the side walls 222, 222). ≪ / RTI >

9B is similar to the embodiment shown in FIG. 9A, except that the light emitting device package 300 is disposed in contact with the bottom cover 210, and the reflector 220 is formed of the side wall 222. FIG.

9C, the reflector 220 includes a side wall 222 and a bottom surface 221. An open region is formed in the bottom surface 221 and a light emitting device package 300 is formed in the open region. Can 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 a pattern 225 is formed on the bottom surface 221 of the reflector 220 and the surface of the side wall 222. The pattern 225 is formed in the regular or irregular pattern of the same material or other materials as the reflector 220 and the light emitted from the light emitting device package 300 is scattered in the pattern 225 to form the optical sheets 230, 240, 250, and 260, respectively.

10A and 10B are enlarged views of still another embodiment of 'A' in FIG.

10A, the reflector 220 includes a vertical portion 224 in contact with the bottom cover 210, a side wall 222 extending from the vertical portion 224, And a fastening portion 223 formed thereon.

The side surface of the light emitting device package 300 is in contact with the vertical portion 224 of the reflector 220 and the bottom surface is disposed in contact with the bottom cover 300. The vertical part 224 can fix the light emitting device package 300 if the interval between the vertical parts 224 of the reflector 220 is the same as the width of the light emitting device package 300.

10B is similar to the embodiment shown in FIG. 10A, except that a pattern 225 is formed on the surface of the side wall 222 of the reflector 220. In FIG.

11A and 11B are enlarged views of still another embodiment of 'A' in FIG.

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

Since the fastening portions 223a fix the optical sheets, the fastening portions 223a do not have to be arranged for every reflection plate around the respective light emitting device packages 300, and the number enough to fix the optical sheets and prevent sagging can be arranged. The reflection plate 220a on which the fastening portions 223a are disposed may be arranged in one to several depending on the size of the panel in which the backlight unit is to be used.

The reflector 220b on which the fastening portion is not provided is composed of the side wall 222b and the support portion 223b. The support portion 223b can be supported only without being fastened to 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 reflector 220b on which the fastening portion is not provided is only a sidewall. That is, at least one of the optical sheets 230, 240, 250 and 260 is in surface contact with the support 220b in FIG. 11A, and at least one of the optical sheets 230, 240, 250, ). ≪ / RTI >

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

In the panel, liquid crystal is positioned between a pair of transparent substrates, and a polarizing plate is placed on each transparent substrate to utilize the 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.

A color filter is provided on the front surface of the panel so that light projected from the panel is transmitted only through red, green, and blue light for each pixel, so that an image can be displayed.

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 sheets 170:
180: Color filter 200: Backlight unit
221: bottom surface 222, 222a, 222b: side wall
223b:
223, 223a: fastening part 224: vertical part
230, 240, 250, 260: optical sheet 230a: body
230b: hole 300: light emitting device package
310: package body 321, 322: first and second lead frames
330: conductive adhesive layer 340: wire
350: molding part 355: phosphor
360: Light emitting element

Claims (21)

Bottom cover;
A light emitting device package array arranged in rows and columns on the bottom cover;
A reflector disposed on the bottom cover; And
And an optical sheet for transmitting light emitted from the light emitting device package array,
Wherein at least one of the reflectors has a fastening portion, a hole is formed in the optical sheet, a hole of the optical sheet is inserted into the fastening portion of the reflector, the reflector includes a bottom surface and a side wall, Wherein a slope in the horizontal direction and a slope in the vertical direction are different from each other. delete delete delete delete The method according to claim 1,
Wherein at least a part of the side wall of the reflection plate has a conical shape. delete The method according to claim 1,
And a lens disposed inside the reflection plate and surrounding the light emitting device package. The method according to claim 1,
The height of the reflector is 15 to 25 millimeters,
Wherein the reflection plate is made of tempered glass. delete The method according to claim 1,
The fastening portion is disposed on an upper portion of the side wall of the reflection plate,
The fastening portion is circular in cross section,
Wherein a pattern is formed on a bottom surface and a surface of the side wall of the reflection plate. delete The method according to claim 1,
An open region is formed on a bottom surface of the reflection plate, the light emitting device package contacts the bottom cover in the open region,
Wherein a side surface of the light emitting device package is in contact with the reflection plate, and a bottom surface of the light emitting device package is in contact with the bottom cover. delete delete The method according to claim 1,
Wherein the reflection plate includes a support portion for supporting the optical sheet,
Wherein at least one of the optical sheets is in surface contact or line contact with the support. delete delete The method according to claim 1,
Wherein each of the light emitting device packages is arranged in parallel in at least one of a row and a row direction. The method according to claim 1,
Wherein each of the light emitting device packages is staggered in at least one of a row and a row direction. delete

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