KR101597574B1 - Module for light guide plate and LED back-light unit using the same - Google Patents

Abstract

The present invention relates to an LED backlight unit and a liquid crystal display using the same. The present invention provides a light emitting device comprising: a circuit board having a mounting portion for mounting a light emitting device package, the circuit board including a conductive layer; A light emitting device package mounted on a mounting portion of the circuit board and electrically connected to the conductive layer; And a coupling surface facing the light extraction surface and the circuit board side, the end side edge of the light extraction surface being a curved surface And a plurality of light guide plates adjacent to each other.

Light guide plate, light emitting device package, circuit board, module, backlight.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED backlight unit and a liquid crystal display using the LED backlight unit,

The present invention relates to an LED backlight unit and a liquid crystal display including such an LED backlight unit.

In general, liquid crystal displays (LCDs) are used in various devices ranging from televisions, notebook computers, monitors for desktop computers, and mobile phones.

Since the LCD itself can not emit light, a light emitting device capable of illuminating the liquid crystal panel is required to display image information.

Since the light emitting device of the LCD is coupled to the back surface of the liquid crystal panel, it is called a backlight unit. The backlight unit forms a uniform surface light source to provide a light source to the liquid crystal panel.

A typical backlight unit includes a light source, a light guide plate, a diffusion sheet, a prism, and a protective sheet. As the light source, a fluorescent lamp such as a mercury cold cathode fluorescent lamp or a light emitting diode may be used.

SUMMARY OF THE INVENTION The present invention provides a light guide plate module capable of reducing the number of LEDs used, reducing the number of LEDs used and improving reliability by improving heat dissipation performance, an LED backlight unit including the LED backlight unit, And a display device.

According to a first aspect of the present invention, there is provided a light emitting device package comprising: a circuit board having a mounting portion for mounting a light emitting device package, the circuit board including a conductive layer; A light emitting device package mounted on a mounting portion of the circuit board and electrically connected to the conductive layer; And a coupling surface facing the light extraction surface and the circuit board side, the end side edge of the light extraction surface being a curved surface And a plurality of light guide plates adjacent to each other.

According to a second aspect of the present invention, there is provided a light emitting device package comprising: a circuit board having a mounting portion for mounting a light emitting device package, the circuit board including a conductive layer; A light emitting device package mounted on a mounting portion of the circuit board and electrically connected to the conductive layer; And a coupling surface facing the light extraction surface and the circuit board side, the end side edge of the light extraction surface being a curved surface A backlight unit including a plurality of light guide plates adjacent to each other; And a liquid crystal panel positioned on the backlight unit.

The present invention has the following effects.

It is possible to reduce the thickness of the backlight unit and reduce the number of light emitting diodes or light emitting device packages to be used per unit area since the angle at which the light emitted from the light emitting diode is spread to the side is further enlarged.

Since the light emitting diode occupies a large proportion of the cost of components used in the backlight unit, this advantage can significantly reduce the manufacturing cost of the backlight unit.

In addition, the light emitting device package may be in direct contact with the lower cover to maximize heat dissipation efficiency, thereby further reducing the thickness of the backlight unit.

In addition, it is possible to optimize the shape of the light guide plate and the shape of the lens used in the light emitting device package, thereby suppressing the generation of fibrillation lines and forming a more uniform light extracting surface.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

It will be appreciated that if a portion of a component, such as a surface, is referred to as " inner ", it means that it is farther from the outside of the device than other portions of the element.

1, the backlight unit or module 100 includes a light guide plate 30 positioned on the upper side of the light emitting device package 20 mounted on the circuit board 10. [

The circuit board 10 is provided with a circuit line of the conductive layer 70 and the light emitting device package 20 is electrically connected to the conductive layer 70 through the leads 25 of the light emitting device package 20.

The light guiding plate 30 includes a receiving portion 31 for receiving the light emitting device package 20 and light emitted from the light emitting device package 20 is guided through the light guiding plate 30 And is emitted through the light extracting surface 30A, which is the outer surface of the light guide plate 30.

At this time, in order to improve the light output efficiency of the light guide plate 30, the light extracting pattern 32 may be provided on at least one side of the light extracting surface 30A or the engaging surface 30B facing the circuit substrate 10 .

The light extracting pattern 32 allows the light reflected through the total internal reflection phenomenon of the light guide plate 30 to be more efficiently emitted to the light extracting surface 30A.

The light emitted from the light emitting device package 20 can emit light to the outside of the light guide plate 20 by the pattern 32. Such a pattern 32 can be formed by a method such as injection, .

The receiving part 31 forms a groove having a predetermined curvature below the light guide plate 30 at a position where the light emitting device package 20 is mounted. The receiving part 31 is formed so that the light spreads more widely in the lateral direction The light directly reaching the light guide plate 30 from the light emitting device package 20 can be effectively blocked.

1, the light-receiving portion 31 may be formed in an arcuate groove shape formed in the light guide plate 30, but may be formed in various shapes such as a spherical surface, an ellipsoidal surface, and a curved surface close to a cube.

The reflecting surface 40 is provided on the surface of the circuit board 10 where the coupling surface 30B of the light guide plate 30 is coupled to improve the efficiency of light extracted through the light extracting surface 30A of the light guide plate 30. [ . In some cases, instead of having a separate reflective surface 40, the conductive layer 70 described above may serve as a reflective surface.

On the other hand, the light emitting device package 20 may be a light emitting diode (LED) package. The light emitting device package 20 includes a package body 21 on which a light emitting diode (LED) (22) may be provided.

The lens 22 refracts the light emitted from the LED so as to uniformly spread in the space. For this purpose, the lens 22 may be provided with a lens groove 23 at the center of the lens 22, 22 may be formed as a curved surface 24.

That is, the lens 22 refracts light so that the light emitted from the light emitting device package 20 can enter the light guide plate 30 with a wide incident angle.

The light emitting device package 20 may be electrically connected to the conductive layer 70 through the lid 25 and the lid 25 may be coupled to the conductive layer 70 through a surface mounting method.

The circuit board 10 to which the light emitting device package 20 is coupled may be positioned on the lower cover 50.

FIG. 2 shows an embodiment in which the backlight unit can be made thinner. That is, a groove-like mounting portion (mounting groove) 11 recessed inwardly is formed in the circuit board 10 and the entire thickness of the module 100 is reduced by mounting the light emitting device package 20 in the mounting groove 11 .

At this time, the leads 25 of the light emitting device package 20 are bent upward and can be coupled to the conductive layer 70 (see FIG. 1) by a bonding layer such as the solder 26.

In this case, since the light emitting device package 20 is located closer to the lower cover 50, it can be more efficient in terms of heat release.

As shown in FIG. 3, it is possible to fabricate a backlight unit having a large area by modularizing such a backlight unit and connecting and assembling a plurality of modules 100A, 100B, etc. to each other.

3, one light source (light emitting device package 20) may be provided in one light guide plate 30A, and two or more light sources may be disposed in one light guide plate 30B as shown in FIG. 4 It is possible.

That is, in some cases, a plurality of unit modules each including four or more light emitting device packages 20 in one light guide plate 30B may constitute a backlight unit.

Such a structure may be more suitable for implementing local dimming using a backlight unit.

That is, the above-described embodiment may be more advantageous in driving all or a part of the backlight unit in accordance with the image implemented in the display panel located on the backlight unit.

If the image includes a dark portion, the light emitting device package 20 configured in the module of the corresponding portion may be turned off or darkened. If the image includes a bright portion, Still, by driving or brighter driving, the contrast ratio (or contrast ratio) can be maximized.

In this case, when one light source (light emitting device package 20) is provided in one light guide plate 30A as shown in FIG. 3, each light source may be a separate unit of driving, and as shown in FIG. 4, When two or more light sources are arranged in the light source unit 30B, these two or more light sources can be grouped into individual units of driving.

The driving of the light emitting device package can be controlled by a controller or a driving unit (not shown) included in the backlight unit.

Meanwhile, as shown in FIG. 5, there may be a gap B between one module 100A and the adjacent module 100B.

Usually, when the backlight unit is driven, the temperature inside the unit can rise, and one of the causes is due to heat generated in the light source. This increase in internal temperature can thermally expand the respective parts of the unit, where the degree to which each part thermally expands may be different.

That is, the light guide plate, the circuit board, the reflector, or the like constituting each module can be thermally expanded. Therefore, when the gap B is not provided, the parts are brought into contact with each other due to such thermal expansion, It is possible.

Therefore, considering the thermal expansion, the gap B between one module 100A and the adjacent module 100B can be placed.

At this time, light exiting through the gap B can be multiply reflected between the light guide plate 30, and when viewed from the outside of the light guide plate 30, the reflected light is concentrated in one place Can be seen.

Accordingly, a relatively bright portion and a dark portion appear at the boundary between the modules 100A and 100B, and a curved line in which such a portion is visible outside the light guide plate 30 may appear.

Such a phenomenon can be improved by forming a curved surface 33 on the upper side of the gap A located at the boundary between the modules 100A and 100B as shown in Fig. That is, by forming the end edge side of the light extracting surface, which is the upper side of the light guide plate 30, with a curved surface, the degree of reflection of light between the gaps A is reduced, So that the occurrence of the wobble line can be suppressed.

The curvature (radius of curvature) of the curved surface 33 applied to the end edge side of the light guide plate 30 can be approximately in the range of about 0.15 to 0.7 of the thickness of the light guide plate 30. The light guide plate 30 can reduce the occurrence of flashing lines that may occur between the modules described above.

Considering that the thickness of the light guide plate used in the present embodiment is 3.0 mm, if the curved surface 33 has a radius of curvature of approximately 0.5 mm to 2.0 mm, it is possible to exhibit the effect of reducing the occurrence of such curved lines.

On the other hand, a more uniform light distribution can be formed by configuring the optical sheets on the modules 100A and 100B.

FIG. 7 shows another embodiment of the module 100 considering the above-mentioned matters. The backlight unit module 100 may include a through hole 12 formed in the circuit board 10 as a mounting portion on which the light emitting device package 20 is mounted.

The light emitting device package 20 is provided inside the through hole 12 and the lead 25 bent upward from the package body 21 is electrically connected to the conductive layer 70 of the circuit board 10 by the solder 26, As shown in FIG.

At this time, since the light emitting device package 20 can directly contact the lower cover 50 of the backlight unit, heat emission efficiency can be greatly improved.

Generally, in the light emitting diode 28, a large amount of heat is generated. Therefore, it is one of important characteristics that the heat is efficiently emitted. The light emitting device package 20 is mounted with a light emitting diode 28 in a mounting groove 27 formed in the package body 21. A heat sink (not shown) (Not shown).

The lower cover 50 of the backlight unit may be made of metal and the light emitted from the light emitting diode 28 may be transferred to the lower cover 50 50). ≪ / RTI >

The lens 22 provided in the light emitting device package 20 has the lens groove 23 formed at the center side inside the lens 22 as in the above embodiment, The curved surface 24 to which the curvature R is applied is applied so that the light emitted from the light emitting diode 28 can be evenly spread.

The distance D between the light emitting diode 28 and the lower end of the lens groove 23 may also be one of the important factors to spread the light evenly.

The condition for the light of the light emitting diode 28 to spread evenly can be analyzed through an experiment as follows.

First, the shortest distance D from the lens groove 23 of the lens 22 to the top surface of the light emitting diode 28 is D1 / 7 larger than D1 / 7 when the diameter of the lens 22 is D1, /2.4 is advantageous.

Further, it is advantageous that the upper surface of the periphery of the lens groove 23 has a curved surface R having at least one curvature, and this curvature has a value of 0.8 mm to 1.8 mm.

The lens groove 23 may have a specific angle? As shown in FIG. 7, and it is advantageous that the angle? Of the lens groove 23 satisfies the condition of 90 ° to 120 °.

The conditions of D, R, and &thetas; are obtained through experiments of the light emitting device package.

The light guide plate 30 disposed on the light emitting device package 20 includes a light extracting surface 30A on which light is emitted and a mating surface 30B facing the light extracting surface 30A facing the circuit board 10, The light extracting pattern 32 may be formed on at least one of the light extracting surface 30A and the engaging surface 30B.

As described above, the curved surface 33 can be formed on the edge (end) side of the light extracting surface 30A of the light guide plate 30 to further suppress the generation of softening rays.

The reflective surface 40 may be provided on the upper surface of the circuit board 10 in the same manner as the above-described embodiment.

8 shows an example in which the modules 100A, 100B and 100C of the backlight unit described in FIG. 7 are connected to each other on the lower cover 50 in a neighboring manner.

The backlight unit in which the plurality of modules 100A, 100B, and 100C are arranged can be greatly reduced in thickness, the heat emission performance of the light emitting diode is greatly improved, So that overall performance can be greatly improved.

Each module including the light guide plate 30 can be manufactured using an injection method. That is, it is possible to manufacture a module having a predetermined size and to manufacture a backlight unit by combining such modules, thereby achieving excellent performance in terms of productivity and reproducibility.

9 and 10 show embodiments of the respective modules 100D and 100E of the backlight unit as described with reference to Fig.

9 shows a module 100D in which four light emitting device packages 20 are provided in one light guide plate 30. In FIG. 10, a module 100E having four square modules as shown in FIG. Respectively.

10 shows a state in which sixteen light emitting device packages 20 are provided on one light guide plate 30. One or more light emitting device packages 20 are freely arranged on one light guide plate 30 And can be used as the unit module 100E.

Each of the unit modules 100D and 100E may be used as a unit of driving for local dimming. That is, the light emitting device package 20 included in each module can be driven simultaneously. It is also possible that the light emitting device package 20 may be driven in units of individual light emitting device packages 20 as occasion demands.

11 shows an embodiment in which a reflection plate 60 is provided on the upper surface of the accommodating portion 34 of the light guide plate 30 to prevent light emitted from the light emitting device package 20 from being directly transmitted to the outside.

The receiving portion 34 of the light guide plate 30 may have a square columnar shape or a cylindrical shape, and each corner of the shape of such a structure may be formed to have a curved surface as shown in FIG.

The reflection plate 60 provided on the upper surface of the receiving part 34 may be formed of a reflection film or a metal layer or may be integrally formed with the light guide plate 30 using an opaque material when the light guide plate 30 is manufactured.

The reflection plate 60 is formed by the light emitted from the light emitting diode 28 is diffused by the lens 22 and then transmitted to the light extraction surface 30A of the light guide plate 30, , It is possible to further improve the visibility of the hot spot on the light extracting surface 30A.

Light that is guided through the side surface of the accommodating portion 34 passes through the light extracting pattern 32 of the light guide plate 30 and is emitted through the light extracting surface 30A. The light thus guided can be uniformly mixed with each other, so that more uniform light can be formed.

As described above, the backlight unit and the module according to the embodiment of the present invention are advantageously used in an advantageous manner by utilizing the advantages of the direct type in which the light of the light emitting diode is directly transmitted to the upper side and the light guide plate method using the light guide plate .

That is, the angle at which the light emitted from the light emitting diode extends to the side is further enlarged to reduce the thickness of the backlight unit, and the number of light emitting diodes or light emitting device packages to be used per unit area can be reduced.

Since the light emitting diode occupies a large proportion of the cost of components used in the backlight unit, this advantage can significantly reduce the manufacturing cost of the backlight unit.

In addition, the light emitting device package may be in direct contact with the lower cover to maximize heat dissipation efficiency, thereby further reducing the thickness of the backlight unit.

In addition, it is possible to optimize the shape of the light guide plate and the shape of the lens used in the light emitting device package, thereby suppressing the generation of fibrillation lines and forming a more uniform light extracting surface.

As shown in Fig. 13, the liquid crystal panel 200 is provided on the above-described backlight unit (hereinafter referred to as reference numeral 100) to constitute the liquid crystal display device 400. [

The liquid crystal panel 200 located on the backlight unit 100 includes a liquid crystal layer 230 injected between upper and lower substrates 210 and 220 facing each other (see FIG. 14).

A driving unit (not shown) for driving the liquid crystal panel 200 may be provided on one side of the liquid crystal panel 200.

A lower cover 310 covering the backlight unit 100 is positioned and an upper cover 320 covering a front surface of the liquid crystal panel 200 may be disposed on the liquid crystal panel 200.

In the liquid crystal panel 200, liquid crystal cells constituting pixel units are arranged in a matrix form, and an image is formed by controlling light transmittance of liquid crystal cells according to image signal information transmitted from a driving unit.

The driving unit may include a flexible printed circuit board (FPC), a driving chip mounted on the flexible printed circuit board, and a circuit board (PCB) connected to the other side of the flexible printed circuit board.

As shown in the figure, the backlight unit 100 is located behind the liquid crystal panel 200, and a plurality of optical sheets 110 may be provided on the backlight unit 100.

The optical sheet 110 is disposed on the rear surface of the liquid crystal panel 200 and may include a diffusion sheet, a prism sheet, and a protective sheet.

Here, the diffusion sheet serves to diffuse light from the backlight unit 100 and supply the light to the liquid crystal panel 200. The prism sheet is formed with a prism having a triangular prism shape on a top surface thereof. The prism sheet functions to condense the light diffused in the diffusion sheet in a direction perpendicular to the plane of the upper liquid crystal panel 200.

The micro prisms formed on the prism sheet have predetermined angles. The light passing through the prism sheet proceeds almost vertically to provide a uniform luminance distribution. The topmost protective sheet protects the prism sheet, which is susceptible to scratches.

14, a plurality of gate wirings and a plurality of data wirings are formed in the form of a matrix on the lower substrate 210 of the liquid crystal panel 200, and pixel electrodes and thin film transistors Thin Film transistor (TFT) 240 are formed.

The signal voltage applied through the thin film transistor 240 is supplied to the liquid crystal layer 230 by the pixel electrode, and the liquid crystal layer 230 is aligned according to the signal voltage to determine the light transmittance.

The upper substrate 220 is provided with a color filter 270 made of RGB pixels having a predetermined color passing therethrough and a common electrode 270 made of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) 260 are formed. Upper and lower sides of the liquid crystal layer 230 may be positioned with the alignment layer 250.

The performance of the liquid crystal display device 400 as described above can be maximized by using the backlight unit 100 described above.

A liquid crystal TV can be constructed using the liquid crystal display device 400 as described above.

The configuration of the liquid crystal TV 500 is as shown in FIG. 15 and the broadcast data stream received from the tuner 510 is supplied to the liquid crystal TV 500 through the processing unit 520, the decoder 530, and the A / V output unit 540. And displayed on the display device 400. [

The operation of the tuner 510 or the processing unit 520 may be controlled through the control unit 550 and the control unit 550 may further include the memory 560. [

When a user selects and designates an arbitrary broadcast channel by operating the liquid crystal TV having such a configuration, the control unit 550 controls the tuner 510 and the processing unit 520 to tune to the corresponding broadcast channel, A data stream of a broadcast program provided through a broadcast channel is separated into audio and video data and the like.

The decoder 530 decodes the data output from the processing unit 520 into audio and video signals and outputs the audio and video signals to the liquid crystal display 400 or the speaker unit 540 through the A / V output unit 540. [ The audio output unit 570 and the like.

At this time, the backlight unit 100 is driven through the backlight driving unit 410 to display a screen displayed on the liquid crystal panel 200.

Meanwhile, the broadcast data stream transmitted to the processing unit 520 may be provided through the Internet.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is natural to belong to the scope.

1 is a sectional view showing a light guide plate module according to a first embodiment of the present invention.

2 is a cross-sectional view illustrating a light guide plate module according to a second embodiment of the light guide plate module.

Figs. 3 and 4 are schematic diagrams showing unit modules arranged to constitute a backlight unit. Fig.

Figs. 5 and 6 are schematic diagrams for explaining a structure for improving generation of fog lines between modules and modules. Fig.

7 is a cross-sectional view illustrating a light guide plate module according to a third embodiment of the present invention.

8 is a cross-sectional view showing the arrangement of the modules of Fig. 7 to construct a backlight unit.

9 and 10 are schematic diagrams showing an example of the configuration of the unit module.

11 is a sectional view showing a light guide plate module according to a fourth embodiment of the present invention.

12 is a cross-sectional view showing that the modules of Fig. 11 are arranged to constitute a backlight unit.

13 is an exploded view showing an example of a liquid crystal display device.

14 is a cross-sectional view showing an example of a liquid crystal panel.

15 is a block diagram showing a liquid crystal TV including a liquid crystal display device.

Claims (18)

In a light emitting diode (LED) backlight unit, A lower cover; A circuit board disposed on the lower cover and having a mounting portion for mounting the light emitting device package, the circuit board including a conductive layer; A light emitting device package mounted on a mounting portion of the circuit board and electrically connected to the conductive layer; And a coupling surface facing the light extraction surface and the circuit board side, the end side edge of the light extraction surface being a curved surface And a plurality of light guide plates connected adjacent to each other, The circuit board includes: A mounting portion for mounting the light emitting device package, wherein a through hole is formed, Wherein the light emitting device package includes: And the LED backlight unit is provided inside the through-hole, and is in direct contact with the lower cover. delete The method according to claim 1, Wherein the light emitting device package includes: Package body; And And a lens positioned on the package body. The method of claim 3, The lens, And a top surface having a curved surface having at least one curvature at a periphery of the groove, wherein the top surface is located on the upper side of the light emitting element of the package body, Is smaller than D1 / 2.4, and D1 / 7 is smaller than D1 / 2.4 when D1 is the diameter of the lens. 5. The method of claim 4, The curvature R of the curved surface of the peripheral portion of the groove of the lens, 0.8 mm < R < 1.8 mm. 5. The method of claim 4, The angle? Of the groove located on the upper surface of the lens is? And 90 DEG <? &Lt; 120 DEG. The method according to claim 1, Wherein the light emitting device package further includes a lead that is located in the through hole and bent upward to be connected to the conductive layer. 8. The method of claim 7, Wherein at least one of the light extracting surface and the coupling surface is provided with a light extracting structure. The method according to claim 1, Wherein the radius of curvature of the curved surface is 0.15 to 0.7 of the thickness of the light guide plate. The method according to claim 1, And a gap is disposed between the adjacent light-guide plates. 11. The method of claim 10, Wherein the curved surface reduces the occurrence of a wicking line that can be seen in the gap. The method according to claim 1, Wherein the light guide plate is provided with a storage unit for storing the light emitting device package. 13. The method of claim 12, Wherein the accommodating portion has a cylindrical or square columnar groove shape. 13. The method of claim 12, Wherein at least a part of the surface of the receiving part is provided with a reflective layer. The method according to claim 1, Wherein the one light guide plate includes a plurality of light emitting device packages. The method according to claim 1, Wherein the LED backlight unit is provided with a reflective surface on the circuit board. delete In a liquid crystal display device, A lower cover; A circuit board disposed on the lower cover and having a mounting portion for mounting the light emitting device package, the circuit board including a conductive layer; A light emitting device package mounted on a mounting portion of the circuit board and electrically connected to the conductive layer; And a coupling surface facing the light extraction surface and the circuit board side, the end side edge of the light extraction surface being a curved surface A backlight unit including a plurality of light guide plates adjacent to each other; And And a liquid crystal panel disposed on the backlight unit, The circuit board includes: A mounting portion for mounting the light emitting device package, wherein a through hole is formed, Wherein the light emitting device package includes: And the liquid crystal display panel is provided inside the through-hole, and is in direct contact with the lower cover.

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