KR102423116B1 - Backlight unit and display device - Google Patents

Abstract

According to the present invention, in a display device including a modular backlight unit composed of a plurality of light guide plates, a high-quality backlight unit and display device capable of minimizing the occurrence of boundary mura such as bright lines or dark lines occurring at the boundary of light guide blocks separated from each other is to provide To this end, the present invention provides a substrate, a plurality of optical assemblies each including a light source mounted on the substrate and a lower light guide plate and arranged in a matrix form, a reflector disposed on the boundary region of adjacent lower light guide plates, a reflector plate, and a lower light guide plate. Provided are a backlight unit and a display device comprising an optical adhesive resin layer disposed on the optical adhesive resin layer and an upper light guide plate disposed on the optical adhesive resin layer.

Description

BACKLIGHT UNIT AND DISPLAY DEVICE

The present invention relates to a backlight unit and a display device capable of a partial driving method such as local dimming or impulsive.

As the modern society gradually develops into an information society, the demand for various display devices is also increasing. Recently, a liquid crystal display device (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED), etc. have been widely used. Among them, the liquid crystal display device is widely used in notebooks, TVs, and mobile devices because it is thin and light, and can be designed with low power and low heat generation.

The liquid crystal display device includes a liquid crystal panel composed of two substrates bonded to each other with a liquid crystal layer interposed therebetween, and a backlight unit disposed below the liquid crystal panel to supply light to the liquid crystal panel. A backlight unit used in a liquid crystal display device includes a direct type backlight unit (Direct Type BLU) and an edge type backlight unit (Edge Type BLU).

The conventional direct method has an excellent image quality improvement effect through local dimming, but has a disadvantage in that it is relatively thick compared to the edge method. On the other hand, the conventional edge method allows a slim design, but has a disadvantage in that local dimming is only possible in a limited form (0D-Dimming or 1D-Dimming).

Accordingly, in recent years, a modular backlight unit composed of a plurality of light guide plates that can be partially driven, such as local dimming or impulsive, which is not limited, is used while using an edge method that enables a slim design. have.

That is, when a modular backlight unit including a plurality of light guide plates that are separated from each other and each form a block is used, it is easy to implement a partial driving method such as local dimming or impulsive, and thus the contrast of a display image can be improved.

1 is a cross-sectional view showing a display module 8 including a conventional modular backlight unit 5 composed of a plurality of light guide plates 3 .

Referring to FIG. 1 , the display module 8 includes a display panel 7 on which an image is displayed and a backlight unit 5 that provides light to the display panel 7 . Specifically, the backlight unit 5 constitutes a module in which a plurality of optical assemblies 4 including a light source 1 , a substrate 2 on which the light source 1 is mounted, and a light guide plate 3 are arranged in a matrix form. . Optical sheets 6 such as a diffusion sheet or a prism sheet may be further disposed between the display panel 7 and the backlight unit 5 .

2 is a plan view showing a conventional modular backlight unit 5 composed of a plurality of light guide plates 3 .

In FIG. 2 , the modular backlight unit 5 in the form of a matrix composed of nine optical assemblies 4 and arranged in a 3×3 arrangement is exemplified. Each of the optical assemblies 4 may be manufactured as an independent assembly, and each optical assembly 4 is disposed adjacent to each other to form a modular backlight unit 5 in the form of a matrix.

1 and 2, in the case of the conventional modular backlight unit 5, the light guide plates 3 constituting each block are spaced apart from each other, and the boundary area 9 between the adjacent light guide plates 3 ) is formed, and at this time, the difference in brightness is recognized in the boundary region 9 . That is, there is a problem in that brightness Mura such as dark lines or bright lines is visually recognized in the boundary region 9 between adjacent light guide plates 3 .

Such a problem is that when a large amount of light leaks from the incident portion of the light guide plate 3 to which the light is incident from the light source 1, a bright line type boundary is formed, and when a small amount of light leaks out, a dark line type boundary is formed. This occurs because the difference in brightness between the light guide plates 3 is recognized.

In this case, in the case of local dimming conditions, that is, when there is a difference in brightness in the light guide plate 3 of all blocks, the difference in brightness occurring in the boundary region 9 of the light guide plate is not a big problem. However, when local dimming is not possible, that is, when uniform brightness is required for the entire screen, the occurrence of brightness mura such as dark or bright lines visible in the boundary area 9 of the light guide block does not realize a uniform display image. cause problems that cannot be As a result, the non-uniform luminance distribution due to the generation of such bright and dark lines degrades the quality of a displayed image.

Accordingly, in the case of the prior inventions, in order to solve the problem of brightness mura occurring at the boundary of the light guide plate block, a method of separating the distance between the light guide plates by a considerable distance was used. However, in order to separate the light guide plates by a considerable distance, a separate optical component must be used, which causes another problem in that the overall thickness of the display device is increased and manufacturing cost is increased.

An object of the present invention is to provide a high-quality backlight unit and a display device that easily implement partial driving methods such as local dimming and impulsive.

According to the present invention, in a display device including a modular backlight unit composed of a plurality of light guide plates, a high-quality backlight unit and display device capable of minimizing the occurrence of boundary mura such as bright lines or dark lines occurring at the boundary of light guide blocks separated from each other Another purpose is to provide

Another object of the present invention is to provide a high-quality backlight unit and display device capable of expressing a uniform luminance distribution as a whole in a display device including a modular backlight unit composed of a plurality of light guide plates.

In order to achieve the above object, the present invention provides a backlight including a substrate, a light source mounted on the substrate, and a lower light guide plate emitting light incident laterally from the light source to the upper surface, and a plurality of optical assemblies arranged in a matrix form. unit is provided. In addition, the backlight unit further includes a reflector disposed above the boundary region of adjacent lower light guide plates, an optical adhesive resin layer disposed on the reflecting plate and the lower light guide plates, and an upper light guide plate disposed on the optical adhesive resin layer.

The reflective plate disposed above the boundary region of the adjacent lower light guide plates serves to shield light emitted through the boundary region, thereby minimizing visible bright lines in the boundary region, thereby reducing the occurrence of brightness mura. In addition, a shielding layer is provided on the lower surface of the reflector to more effectively shield light.

In addition, the reflector serves to scatter or reflect light, thereby minimizing the visible dark lines in the boundary area, thereby reducing the occurrence of brightness mura.

Specifically, the reflective plate may be disposed so as to be in contact with upper end surfaces of adjacent lower light guide plates, or when both upper ends of the lower light guide plate have a step difference, the reflector plate may be disposed between adjacent stepped regions.

In addition, the optical adhesive resin layer may be applied to cover exposed surfaces of the reflective plate and the lower light guide plate. In addition, the upper surface of the upper light guide plate may have a light exit pattern, and the lower surface of the lower light guide plate may have a lenticular pattern.

In addition, the difference in refractive index between the lower light guide plate, the upper light guide plate, and the optical resin adhesive layers is set to 0.5 or less to minimize interlayer refraction or reflection of light that may be generated between the layers.

Also, in order to achieve the above object, the present invention provides a backlight unit including a light source and a lower light guide plate for emitting light incident laterally from the light source to an upper surface, and including a plurality of optical assemblies arranged in a matrix form. In addition, the backlight unit has a light source mounted on one surface and a reflective layer on the other surface. It further includes an disposed upper light guide plate.

Specifically, since the reflective layer is provided on one surface of the substrate, it can play a role similar to that of the reflective plate in the above-described embodiment.

That is, in the substrate disposed above the boundary region of the adjacent lower light guide plates, one surface of the substrate on which the light source is mounted serves to shield the light emitted through the boundary region, thereby minimizing the visibility of bright lines in the boundary region, thereby reducing brightness mura. It serves to reduce

In addition, in the substrate disposed above the boundary region of the adjacent lower light guide plates, one surface provided with the reflective layer serves to scatter or reflect light, thereby minimizing the visibility of dark lines in the boundary region, thereby reducing the occurrence of brightness mura. do.

In addition, the substrate may be disposed so as to be in contact with upper end surfaces of adjacent lower light guide plates or, when both upper ends of the lower light guide plate have a step difference, the substrate may be disposed between adjacent stepped regions.

Also, in order to achieve the above object, the present invention provides a display device including the aforementioned backlight unit and a display panel receiving light from the backlight unit and displaying an image.

Through this, the backlight unit and the display device according to the present invention can minimize the occurrence of boundary mura such as bright or dark lines occurring at the boundary of the light guide block separated from each other, and can express a uniform luminance distribution as a whole.

The backlight unit and display device according to the present invention have the effect of effectively realizing a partial driving method of the backlight unit such as local dimming or impulsive while reducing the thickness of the backlight unit.

In addition, the backlight unit and the display device according to the present invention have an effect of minimizing the occurrence of mura, such as bright lines or dark lines, which are generated at the boundary between the separated blocks of the lower light guide plate.

In addition, the backlight unit and the display device according to the present invention can be used by directly stacking optical sheets on the upper side of the single upper light guide plate, so that a thin display device can be implemented.

In addition, the backlight unit and the display device according to the present invention have the effect of improving a contrast ratio (CR) and reducing power consumption when the backlight is locally dimmed according to an image signal.

In addition, since the backlight unit and the display device according to the present invention are made by assembling a plurality of optical assemblies, there is an effect of reducing the occurrence of defects in individual optical assemblies and improving process reliability and quality.

1 is a cross-sectional view showing a conventional display module including a modular backlight unit composed of a plurality of light guide plates.
2 is a plan view illustrating a conventional modular backlight unit including a plurality of light guide plates.
3 is a schematic cross-sectional view of a backlight unit according to an embodiment of the present invention.
4 is a plan view illustrating a plurality of optical assemblies arranged in a matrix form according to an embodiment of the present invention.
5A and 5B are cross-sectional views illustrating that a lenticular pattern is formed on a lower surface of a lower light guide plate according to an embodiment of the present invention.
6A to 6D are cross-sectional views of various embodiments of a reflector according to the present invention.
7 is a plan view of a light exit pattern formed on an upper light guide plate according to an embodiment of the present invention.
8 is a schematic cross-sectional view of a backlight unit according to another embodiment of the present invention.
9A and 9B are enlarged cross-sectional views of a portion A of the backlight unit according to the embodiment of FIG. 8 .
10 is a schematic cross-sectional view of a backlight unit according to another embodiment of the present invention.
11 is a schematic cross-sectional view of a backlight unit according to another embodiment of the present invention.
12A to 12C are diagrams for confirming whether boundary mura occurs in the conventional technique using the modular backlight unit and the embodiment of the present invention.
13A to 13C are diagrams illustrating the effect of block division and reduction of mura in the boundary area during full driving and local dimming in the backlight unit according to an embodiment of the present invention.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

In the following, the provision or arrangement of an arbitrary component on the “upper (or lower)” or “top (or below)” of the substrate means that any component is provided or disposed in contact with the upper surface (or lower surface) of the substrate. It is not intended to mean, but is not limited to, the inclusion of other components between the substrate and any component provided or disposed on (or under) the substrate. In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It should be understood that each component may be “interposed” or “connected,” “coupled,” or “connected” through another component.

3 is a schematic cross-sectional view of a backlight unit according to an embodiment of the present invention.

The backlight unit 50 according to an embodiment of the present invention includes a substrate 20, a light source 10 mounted on the substrate 20, and a lower light guide plate ( 30) and a plurality of optical assemblies 40 arranged in a matrix form. In addition, the reflective plate 60, the reflective plate 60, and the optical adhesive resin layer 70 and the optical adhesive resin layer disposed on the lower light guiding plates 30 are disposed on the boundary region 34 of the adjacent lower light guiding plates 30. It further includes an upper light guide plate 80 disposed on the 70 .

Hereinafter, each component will be described in more detail.

The light source 10 is mounted on one surface of the substrate 20 , and at least one light source 10 mounted on the substrate 20 is preferably mounted, that is, mounted in the form of a light source array. The type of the substrate 20 used is not particularly limited, but a metal PCB, a flexible printed circuit board (FPCB), or a general PCB may be used.

The type of the light source 10 is also not particularly limited, but it is preferable to use a Light Emitting Device (LED). It is preferable that the light source 10 be spaced apart from the lower light guide plate 30 by a predetermined distance so that the light is incident on the side, which is the incident surface of the lower light guide plate 30 , when the light is incident into the lower light guide plate 30 . When the light from the light source 10 is incident on the side surface of the lower light guide plate 30 , the light is emitted with a predetermined angle of incidence.

As described above, on one lower light guide plate 30 constituting one optical assembly 40 , the light source 10 is disposed in an array form. In this case, the number of light sources 10 disposed in the light source 10 array may be adjusted according to an area and required brightness. That is, the light source assembly comprising the substrate 20 and the light source 10 is disposed on one side of the lower light guide plate 30 and distributes light over the entire surface through the lower light guide plate 30 to supply the surface light source to the liquid crystal panel. .

The optical assemblies 40 including the substrate 20 , the light source 10 , and the lower light guide plate 30 are arranged in a matrix form to form the modular optical assembly 40 .

4 is a plan view illustrating that a plurality of optical assemblies 40 are arranged in a matrix form according to an embodiment of the present invention. In FIG. 4 , the optical assembly 40 in a 1×3 arrangement is taken as an example, but the number of the arrangement is not limited thereto.

The lower light guide plates 30 are arranged in a matrix form, and a space region 34 is formed between adjacent blocks in the Y-axis direction between the lower light guide plates 30 , and the light source 10 is disposed in the area. In this case, the light source 10 is preferably arranged in the form of a light source array (array). Since the light source 10 is disposed to be spaced apart from the lower light guide plate 30 by a predetermined distance, a space region 34 in which the light source 10 can be disposed is formed between adjacent blocks in the Y-axis direction between the lower light guide plates 30 . . At this time, the local dimming block in the Y-axis direction representing the Y-block is implemented due to the division of the lower light guide plate 30 .

In addition, the light source array consisting of a plurality of light sources 10 constitutes a block as a driving unit of the LED and implements a local dimming block in the X-axis direction representing the X block through driving control for each block.

Meanwhile, the lower light guide plate 30 refracts and scatters light incident from the light source 10 to the side surface of the lower light guide plate 30 , and guides the light to emit light toward the upper surface of the lower light guide plate 30 having the display panel.

The lower light guide plate 30 is made of a transparent material, and for example, preferably one of an acrylic resin series such as PMMA (polymethyl metaacrylate), polyethylene terephthlate (PET), PC (poly carbonate), and polyethylene naphthalate (PEN) resins. However, the present invention is not limited thereto.

In this case, it is preferable to form the lower light guide plate 30 by an extrusion method, which is simpler to manufacture than an injection method and reduces costs.

5A and 5B are cross-sectional views illustrating that a lenticular pattern is formed on a lower surface of a lower light guide plate according to an embodiment of the present invention.

On the lower surface of the lower light guide plate 30, various lower patterns ( 32) can be formed.

The lower pattern may have various patterns such as a prism shape and a prism shape pattern with a round vertex, and is not limited to a specific pattern, but is preferably formed in a lenticular pattern. When the lenticular pattern is formed, it helps to improve straightness by guiding light and increases the efficiency of local dimming.

Referring back to FIG. 3 , the reflective plate 60 is disposed above the boundary area 34 of the adjacent lower light guide plates 30 to correspond to the boundary area 34 .

The reflective plate 60 may be disposed to be spaced apart from the upper surface of the lower light guide plate 30 by a predetermined distance, but is preferably disposed so as to be in contact with the upper surface of the lower light guide plate 30 . When the reflective plate 60 is disposed to be in contact with the upper surface of the lower light guide plate 30 , it is preferably disposed to be in contact with a partial region 66 of the upper end of the lower light guide plate 30 , in the case of the upper surface of the lower light guide plate 30 . In addition to the area 66 in contact with the reflecting plate, an area 68 not in contact with the reflecting plate is generated.

Since the reflecting plate 60 may use any material as long as it has a property capable of reflecting light, the material and the structure of the reflecting plate 60 are not particularly limited. In this case, it is preferable that the reflectivity of the reflector is 80% or more, and when it is less than 80%, the light reflection efficiency by the reflector is lowered, and thus there is a problem in that it is difficult to reduce mura in the boundary region and ensure light uniformity.

The reflector 60 itself may be composed of only a single material having a reflective property, but a reflective plate having a reflective property by forming a reflective layer on both upper and lower surfaces or one surface of a plate made of a non-reflective material. (60) may be provided. For example, the reflector 60 may be provided using a substrate such as a PCB. That is, a light source array may be mounted on one surface of the PCB substrate and a reflective layer may be coated on the other surface to be used as the reflective plate 60 according to an embodiment of the present invention.

6A to 6D are cross-sectional views of various embodiments of the reflector 60 according to the present invention.

6A shows an embodiment in which the reflective plate 60 is formed of a single layer of a material having a reflective property.

6B shows an embodiment in which the reflective plate 60 includes a reflective layer 61 for reflecting light on an upper surface and a shielding layer 62 for shielding light on a lower surface. In this case, the shielding layer may be provided in the same manner as coating black ink.

6c shows an embodiment in which the upper and lower surfaces of the reflective plate 60 are provided to have reflective properties, and the reflective layer 61 of the upper surface and the reflective layer 61 of the lower surface are adhered with the adhesive layer 63 interposed therebetween. show

6D shows that the upper surface of the reflective plate 60 has reflective properties and the lower surface has shielding properties. An example is shown.

In summary, when the upper surface of the reflective plate 60 has a reflective characteristic, a separate layer having any one of a reflective characteristic or a shielding characteristic may be additionally formed on the lower surface of the reflective plate 60 . Therefore, the reflector 60 may be formed of a multi-layer of various combinations as described above.

The reflector 60 is disposed to correspond to the boundary area 34 between the adjacent lower light guide plate and the lower light guide plate, and reduces the occurrence of brightness mura in the boundary area such as a bright line or dark line in the boundary area, thereby solving the problem of luminance non-uniformity. This ensures uniformity of light.

Specifically, the reflector 60 disposed on the upper side of the light source 10 array serves to hide the light source 10 and block the bright light emitted from the light source 10 from being directly emitted from the boundary region and directly viewed. .

Taking the case of the reflective plate 60 having the lower surface of the reflective plate 60 having a reflective characteristic, for example, light emitted from the light source 10 disposed between the boundary regions 34 of adjacent lower light guide plates to the reflective plate 60 is the reflective plate. It is reflected from the lower surface of 60 and returns to the lower direction in which the lower light guide plate 30 is disposed. That is, since the light directly emitted from the light source 10 is reflected back by the reflecting plate 60 between the boundary regions 34 of the adjacent lower light guide plates, an effect such as blocking the light occurs, thereby reducing the visibility of bright lines. can do it

Taking the case of the reflecting plate 60 having a shielding property on the lower surface of the reflecting plate 60 as an example, the light emitted from the light source 10 disposed between the boundary regions 34 of adjacent lower light guide plates directly to the reflecting plate 60 is the reflecting plate. Blocked or absorbed by the shielding layer on the lower surface of (60). That is, since the light directly emitted from the light source 10 between the boundary regions 34 of the adjacent lower light guide plates is blocked by the shielding layer of the reflective plate, it is possible to reduce the visibility of the bright line.

In addition, the reflector 60 serves to reduce the visibility of bright lines as well as the optical adhesive resin layer 70 and the upper light guide plate 80 to reduce the visibility of dark lines in the boundary region 34 of the lower light guide plates. does it This is realized by the reflection characteristics of the upper surface of the reflector 60 , and the optical adhesive resin layer 70 and the upper light guide plate 80 will be described first and then in detail.

Referring to FIG. 3 , an optical bonding resin is applied on the reflection plate 60 and the lower light guide plates 30 to form the optical bonding resin layer 70 . The optical adhesive resin is an adhesive material, and it is preferable to use a resin that transmits light, such as an optical clear adhesive material. The optical adhesive resin layer 70 is applied and formed so as to contact all surfaces of the reflective plate 60 and the lower light guide plate 30 exposed to the outside. That is, it is preferable that all surfaces of the reflective plate 60 and the lower light guide plate 30 exposed to the outside are surrounded by the optical adhesive resin layer 70 .

In addition, the lower surface of the optical adhesive resin layer 70 is applied so as to be in contact with the reflective plate 60 and the lower light guide plate 30 , so it is not necessary to form a flat layer. However, the upper surface of the optical adhesive resin layer 70 is preferably provided as a flat surface because other layers such as the upper light guide plate 80 may be additionally disposed thereon. That is, according to an embodiment of the present invention, the upper surface of the optical resin adhesive layer 70 applied on the reflecting plate 60 and the lower light guide plate 30 is formed to be flat, and the upper light guide plate 80 is formed on the optical resin adhesive layer 70 . ) is preferably arranged so as to be in contact.

Referring to FIG. 3 , the upper light guide plate 80 is preferably manufactured in a single piece having a size corresponding to the entire display device. On the other hand, it is preferable to manufacture a plurality of the lower light guide plate 30 described above so that blocks can be formed as much as a desired divided area.

It is preferable that the lower light guide plate 30 and the upper light guide plate 80 are separately manufactured and then integrated with an optical adhesive resin. At this time, it is preferable to form the upper light guide plate 80 by an extrusion method, which is simpler and less expensive than the injection method.

In this case, the refractive indices of the optical adhesive resin layer 70 , the lower light guide plate 30 , and the upper light guide plate 80 are preferably configured to be the same or as similar as possible. Preferably, the difference in refractive indices between them is preferably 0.5 or less.

This means that the light emitted through the lower light guide plate 30 reaches the optical adhesive resin layer 70 and the upper light guide plate 80 , or is reflected from the upper light guide plate 80 back to the lower surface and passes through the optical adhesive resin layer 70 . This is to maximally prevent the light reaching the lower light guide plate 30 from being refracted or reflected due to a difference in refractive index between the layers. That is, when the difference in the refractive index exceeds 0.5, a phenomenon in which some light is refracted or reflected in each layer is increased, and thus a problem in which the luminance of the display is reduced as a whole may occur.

7 is a plan view of the light exit pattern 82 formed on the upper light guide plate 80 according to an embodiment of the present invention.

It is preferable to form a predetermined light exit pattern 82 whose density is controlled for uniform luminance on the upper surface of the upper light guide plate 80 . The pattern may be formed through a roll stamping method or an imprinting method, and the method of the pattern is not particularly limited.

At this time, it is preferable that the density of the light exit pattern 82 on the upper surface of the upper light guide plate 80 is distributed from a small pattern to a denser pattern on the light source 10 side. In this case, as a method of controlling the density, a method of implementing various patterns may be selected through i) changing the size of the pattern ii) changing the number of patterns iii) changing the size and number of patterns.

Hereinafter, the effect of reducing the visibility of dark lines in the boundary region 34 of adjacent lower light guide plates through the provision of the reflecting plate 60, the optical resin adhesive layer 70, and the upper light guide plate 80 will be described in detail.

In this regard, referring to FIG. 3 , among the light incident on the incident surface of the lower light guide plate 30 from the light source 10 , the light emitted to the upper surface of the lower light guide plate 30 passes through the optical adhesive resin layer 70 and passes through the upper light guide plate. (80) is entered. Among the light incident to the upper light guide plate 80 , some of the light is emitted through the upper surface of the upper light guide plate 80 , and some of the light is reflected from the area 84 on the upper surface of the upper light guide plate 80 , in which the light exit pattern is not formed, and then again The upper light guide plate 80 returns to the lower surface direction. At this time, since some of the light returning to the lower surface of the upper light guide plate 80 is reflected back by the reflecting plate 60 disposed in the boundary region of the adjacent lower light guide plates 30 , the area where the reflecting plate 60 is disposed, that is, It allows light to be evenly emitted from the boundary regions 34 of adjacent lower light guide plates.

That is, due to the reflective characteristics of the upper surface of the reflector 60 , it reduces the visibility of dark lines in a specific area such as the boundary region 34 of adjacent lower light guide plates and allows light to be emitted evenly from the entire upper light guide plate 80 . At this time, the light exit pattern 82 formed on the upper surface of the upper light guide plate 80 serves to help the light to be evenly distributed and emitted. In order to obtain a uniform brightness of the entire surface of the display, it can be adjusted through appropriate density control in the outgoing light pattern 82 .

Referring to FIG. 3 , the reflective members 90 and 92 may be additionally disposed on the lower surface or the lower surface and side surfaces of the light guide plate to prevent loss of light generated from the light source. The reflective members 90 and 92 allow the light incident on the side surface of the lower light guide plate 30 to be guided inside the light guide plate, reflected by the reflection members 90 and 92 and then emitted to the upper surface of the lower light guide plate 30 so that light Brightness can be improved. The reflective members 90 and 92 may be provided as a reflective sheet having a reflectivity of a predetermined size by coating at least one surface of a reflective material.

8 is a schematic cross-sectional view of a backlight unit 50 according to another embodiment of the present invention.

In the backlight unit according to another embodiment of the present invention shown in FIG. 8 , steps 36 are formed at both ends of the upper surface of the lower light guide plate 30 , which will be described in detail below. For reference, differences from the backlight unit according to the embodiment of the present invention will be described with reference to FIG. 3 , and additional descriptions of other overlapping contents will be omitted.

The lower light guide plate 30 has a step shape with steps 36 provided at both ends of the upper surface so that the reflector 60 can be inserted thereinto. In this case, the step 36 may be provided by post-processing after extrusion or by manufacturing the lower light guide plate 30 through injection.

The reflection plate 60 may be inserted at the same height as the step-shaped region of the lower light guide plate 30 formed due to the step 36 , and may be inserted in contact with the lower light guide plate 30 , but is not limited thereto. That is, the reflector 60 and the lower light guide plate 30 may be in contact with the reflector 60 in a state where the height of the reflector 60 is low compared to the height of the step shape formed due to the step 36, and compared to the distance between the steps, the reflector ( Because the length of the reflection plate 60 is short, the side surface of the reflection plate 60 and the side surface of the lower light guide plate 30 may not directly contact, but only a portion of the lower surface of the reflection plate 60 may be in contact with the lower light guide plate 30 .

9A and 9B are enlarged views of A in the backlight unit 50 according to the embodiment of FIG. 8 , and are cross-sectional views of portions in which the optical adhesive resin layer 70 is formed.

As described above, the reflective plate 60 is inserted into the region between the steps formed at both ends of the upper surface of the lower light guide plate 30, and FIG. 9A shows an embodiment in which the reflective plate 60 is properly inserted between the steps. At this time, both sides of the reflecting plate 60 are disposed to be in contact with the lower light guide plate 30 in a state where the height of the reflecting plate 60 and the step shape formed by the step are the same or almost similar, and the optical adhesive resin layer 70 The silver is applied and disposed only on the upper surface of the reflective plate 60 .

In contrast, FIG. 9B illustrates an embodiment in which the length of the reflection plate 60 is shorter than the length of the region between the steps formed at both ends of the upper surface of the lower light guide plate 30 . At this time, the space 72 created because the side surface of the reflecting plate 60 does not directly contact the side surface of the lower light guide plate 30 is coated with the optical adhesive resin and filled with the optical adhesive resin.

That is, the optical adhesive resin layer 70 is preferably filled so that there is no empty space between the reflecting plate 60 and the lower light guide plate 30 , which is the lower light guide plate 30 and the upper light guide plate having the same or similar refractive index. (80) is also cemented by an optical adhesive resin having the same or similar refractive index, so that light is not well refracted inside the three layers.

A display panel that receives light from the backlight unit 50 and displays an image is disposed above the backlight unit 50 to provide a display device in which occurrence of boundary mura is reduced. The display panel may be disposed to correspond to the upper light guide plate 80 , and a plurality of divided regions may be disposed to correspond to the plurality of lower light guide plates 30 .

10 is a schematic cross-sectional view of a backlight unit according to another embodiment of the present invention.

The backlight unit 50 according to an embodiment of the present invention includes a light source 10 and a lower light guide plate 30 for emitting light incident to the side from the light source 10 to the upper surface, and includes a plurality of matrix types. optical assemblies 40 . In addition, the light source 10 is mounted on one surface, a reflective layer is provided on the other surface, and the substrate 20, the substrate 20 and the lower light guide plates 30 are disposed above the boundary region of the adjacent lower light guide plates 30. It further includes an optical adhesive resin layer 70 and an upper light guide plate 80 disposed on the optical adhesive resin layer 70 .

The exemplary embodiment of the present invention illustrated in FIG. 10 will be described in detail with respect to parts that are different from the contents of the other exemplary embodiments described above, and additional descriptions of other overlapping contents will be omitted.

According to an embodiment of the present invention shown in FIG. 10, a reflective layer is provided on one or both surfaces of the substrate 20, so that the same effect can be obtained without a separate reflective plate 60, unlike the embodiment described with reference to FIG. .

That is, the light source 10 may be mounted on one surface of the substrate 20 and the reflective layer may be provided on the other surface, and the reflective layer may also be provided on the surface of the substrate 20 on which the light source 10 is mounted. can In addition, when the substrate 20 itself has a reflective characteristic, it is not necessary to provide a separate reflective layer, and the substrate 20 itself having the reflective characteristic can be used like the reflective plate 60 . Therefore, the term "substrate 20 with a reflective layer" defined in the present invention means that not only the substrate 20 is provided with a separate reflective layer, but also the substrate 20 itself has reflective properties, so it is not necessary to provide a separate reflective layer. Includes all substrates.

In this case, one surface of the substrate 20 on which the light source 10 is mounted is directed downward so that the light sources 10 are spaced apart from each other in the boundary area of the adjacent lower light guide plates 30 .

The upper surface of the substrate 20 provided with the reflective layer faces upward, and one surface of the substrate 20 on which the light source 10 is mounted is disposed above the boundary region of the adjacent lower light guide plates 30 . In this case, the substrate 20 may be disposed so as to be in contact with a portion of the upper ends of the adjacent lower light guide plates 30 .

The substrate 20 provided with the reflective layer serves as the reflective plate 60 as described in another embodiment, thereby reducing the visibility of bright or dark lines in the boundary region of the adjacent lower light guide plates 30 .

11 is a schematic cross-sectional view of a backlight unit according to another embodiment of the present invention.

In the backlight unit according to another embodiment of the present invention shown in FIG. 11 , steps 36 are formed at both ends of the upper surface of the lower light guide plate 30 , which will be described in detail below. For reference, differences from the backlight unit according to an embodiment of the present invention according to FIG. 10 will be mainly described, and additional descriptions of other overlapping contents will be omitted.

The lower light guide plate 30 has a step shape with steps 36 provided at both ends of the upper surface so that the substrate 20 can be inserted. In this case, the step 36 may be provided by post-processing after extrusion or by manufacturing the lower light guide plate 30 through injection.

The substrate 20 may be inserted equal to the height of the stepped region of the lower light guide plate 30 formed due to the step 36 , and may be inserted in contact with the lower light guide plate 30 , but is not limited thereto. That is, the substrate 20 and the lower light guide plate 30 may be in contact with the substrate 20 in a state where the height of the substrate 20 is low compared to the height of the step shape formed due to the step 36, and compared to the distance between the steps, the substrate ( Since the length of the substrate 20 is short, the side surface of the substrate 20 and the side surface of the lower light guide plate 30 may not directly contact, but only a portion of the lower surface of the substrate 20 may be in contact with the lower light guide plate 30 .

12A to 12C are diagrams illustrating whether boundary mura occurs in the conventional technique using the modular backlight unit and the embodiment of the present invention.

12A is prepared to measure whether boundary mura occurs, and three lower light guide plates and three LED arrays are arranged. In this case, the length d1 of the lower light guide plate was 40 mm and d2 was 68 mm. 12B is a view showing measurement results when driving a conventional modular backlight unit in which a lower light guide plate and an LED array are disposed in a full white image. 12C is a view showing measurement results for a modular backlight unit according to an embodiment of the present invention in which a reflector, an optical adhesive resin layer, and an upper light guide plate are stacked in addition to a conventional modular backlight unit in which a lower light guide plate and an LED array are disposed.

As shown in FIG. 12B , it can be confirmed that boundary mura is generated in the case of the conventional modular backlight unit. On the other hand, it can be seen that the generation of boundary mura in the boundary region is not confirmed in FIG. 12C according to the embodiment of the present invention, as can be seen in the drawings.

13A to 13C are diagrams for confirming the block division effect and mura removal in the boundary area during full driving and local dimming in the backlight unit according to an embodiment of the present invention.

As can be seen in FIG. 13A , the backlight unit according to an embodiment of the present invention forms nine blocks, and an LED array is disposed between boundary regions of each block.

13B shows that full driving is performed, and boundary mura is not confirmed in each boundary region. Specifically, it is driven with all blocks turned on.

13C shows that the local dimming operation is performed, and it can be seen that the division effect is effectively generated for each block. Specifically, blocks #1-2, #2-1, #2-3, and #3-2 are turned on and driven, and the remaining blocks are not driven in an off state.

In the above, although the embodiment of the present invention has been mainly described, various changes or modifications may be made at the level of those skilled in the art. Accordingly, it will be understood that such changes and modifications are included within the scope of the present invention without departing from the scope of the present invention.

1: light source 2: substrate
3: light guide plate 4: optical assembly
5: backlight unit 6: optical sheet
7: display panel 8: display module
9: boundary area of light guide plate 100: liquid crystal display device
10: light source 20: substrate
30: lower light guide plate 32: lower pattern of lower light guide plate
34: boundary area of the adjacent lower light guide plate
36: step of lower light guide plate 40: optical assembly
50: backlight unit 60: reflector
66: area in contact with the reflector 68: area not in contact with the reflector
70: optical adhesive resin layer 80: upper light guide plate
82: light output pattern of the upper light guide plate
84: area where the light exit pattern of the upper light guide plate is not formed
90: lower reflective member 92: side reflective member

Claims (17)

a plurality of optical assemblies each including a substrate, a light source mounted on the substrate, and a lower light guide plate for emitting light incident laterally from the light source to an upper surface, the plurality of optical assemblies being arranged in a matrix;
a reflection plate disposed in contact with upper surfaces of the lower light guide plates and disposed to overlap a spatial area of the lower light guide plate on which the light sources are disposed;
an optical adhesive resin layer disposed on the reflection plate and the lower light guide plates; and
and an upper light guide plate disposed on the optical adhesive resin layer,
the light source is disposed within the spatial area,
The light source and the reflector are positioned to overlap each other in the vertical direction,
A lower pattern for guiding light is provided on a lower surface of the lower light guide plate,
A light exit pattern is provided on an upper surface of the upper light guide plate, and a density of the light exit pattern disposed in an area overlapping the light source is greater than a density of the light exit pattern disposed in an area not overlapping the light source.
According to claim 1,
The reflector is a backlight unit disposed at upper ends of the adjacent lower light guide plates.
According to claim 1,
Both ends of the upper surface of the lower light guide plate have a step difference,
The reflective plate is disposed between the adjacent stepped areas,
A length of the reflection plate is smaller than a distance between the step areas.

delete According to claim 1,
The optical adhesive resin layer is applied to cover exposed surfaces of the reflection plate and the lower light guide plate.
According to claim 1,
A reflective layer is provided on the upper surface of the reflective plate,
A backlight unit provided with a reflective layer or a shielding layer on a lower surface of the reflective plate.
a plurality of optical assemblies each including a light source and a lower light guide plate for emitting light incident laterally from the light source to an upper surface and arranged in a matrix;
a substrate on which the light source is mounted on one surface, a reflective layer on the other surface, and disposed above a boundary region of the adjacent lower light guide plates;
an optical adhesive resin layer disposed on the substrate and the lower light guide plates; and
and an upper light guide plate disposed on the optical adhesive resin layer,
The light source is disposed within the boundary region,
The light source and the substrate are positioned to overlap each other in a vertical direction.
8. The method of claim 7,
The substrate is a backlight unit disposed at upper ends of the adjacent lower light guide plates.
8. The method of claim 7,
Both ends of the upper surface of the lower light guide plate have a step difference,
The substrate is a backlight unit disposed between adjacent areas of the steps.
8. The method of claim 7,
The substrate is a backlight unit disposed to be in contact with the lower light guide plate.
8. The method of claim 7,
The optical adhesive resin layer is applied to cover exposed surfaces of the substrate and the lower light guide plate.
8. The method of claim 7,
A backlight unit having an upper surface of the upper light guide plate having a light output pattern.
8. The method of claim 7,
A backlight unit having a lenticular pattern on a lower surface of the lower light guide plate.
8. The method of claim 1 or 7,
A difference in refractive index between the lower light guide plate, the upper light guide plate, and the optical adhesive resin layer is 0.5 or less.
A plurality of optical assemblies each including a substrate, a light source mounted on the substrate, and a lower light guide plate emitting light incident laterally from the light source to an upper surface and arranged in a matrix;
a reflective plate disposed above a boundary region of the adjacent lower light guide plates;
an optical adhesive resin layer disposed on the reflection plate and the lower light guide plates;
a backlight unit including an upper light guide plate disposed on the optical adhesive resin layer; and
a display panel disposed on the backlight unit and receiving light from the backlight unit to display an image;
The light source is disposed within the boundary region,
The light source and the reflector are positioned to overlap each other in a vertical direction.
A plurality of optical assemblies each including a light source and a lower light guide plate for emitting light incident laterally from the light source to an upper surface and arranged in a matrix;
a substrate on which the light source is mounted on one surface, a reflective layer on the other surface, and disposed above the boundary area of the adjacent lower light guide plates;
an optical adhesive resin layer disposed on the substrate and the lower light guide plates;
a backlight unit including an upper light guide plate disposed on the optical adhesive resin layer; and
a display panel disposed on the backlight unit and receiving light from the backlight unit to display an image;
The light source is disposed within the boundary region,
The light source and the substrate are positioned to overlap each other in a vertical direction.
8. The method of claim 7,
The light source is disposed on the lower surface of the substrate,
The reflective layer is a backlight unit disposed on an upper surface of the substrate.

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