KR20150065318A - Backlight unit and display device including the same - Google Patents

Abstract

The present invention relates to a backlight unit and a display device including the same. The backlight unit includes a driving substrate, a plurality of light sources which are arranged on the driving substrate, an optical sheet which is arranged on the light sources, and a plurality of support stands which are interposed between the driving substrate and the optical sheet to support the optical sheet. The support stand is arranged on the driving substrate and includes a first support part which includes a reflection surface on the outer side thereof and a second support part which is arranged on the first support part and supports the optical sheet.

Description

BACKLIGHT UNIT AND DISPLAY DEVICE CONTAINING THE SAME BACKLIGHT UNIT AND DISPLAY DEVICE INCLUDING THE SAME

The present invention relates to a backlight unit and a display device including the same.

2. Description of the Related Art A liquid crystal display (LCD) is a device that converts various electrical information generated in various devices into visual information by using a change in liquid crystal transmittance according to an applied voltage. The liquid crystal display device is widely used because it is not self-luminous and requires backlight but can be realized in a lightweight and thin shape with low power consumption.

In addition, a liquid crystal display device is provided with a backlight unit (BLU) which is a light emitting device that provides light to the backside of a liquid crystal panel on which an image is displayed because it is not self-luminous.

The liquid crystal display includes a liquid crystal panel including a color filter substrate and an array substrate, a color filter substrate, and an array substrate interposed between the color filter substrate and the array substrate, the backlight unit irradiating light to the liquid crystal panel, and the like.

BACKGROUND ART A backlight unit used in a liquid crystal display device can be classified into an edge type and a direct type according to the position of a light emitting diode (LED) as a light source.

In the edge type backlight unit, the light emitting diodes as light sources are disposed on the side surface of the light guide plate, and the light guide plate irradiates light emitted from the light emitting diodes toward the liquid crystal panel through total reflection.

A direct-type backlight unit uses a diffusion plate instead of the light guide plate, and the light emitting diodes are disposed on the rear surface of the liquid crystal panel. Accordingly, the light emitting diodes irradiate light toward the rear surface of the liquid crystal panel.

Recently, liquid crystal display devices have become larger and thinner.

Accordingly, attempts have been made to reduce the interval between the light emitting diode and the optical sheet in order to thin the backlight unit. It is important to maintain proper spacing between the optical sheet and the light emitting diode in order to secure the luminance uniformity of the backlight unit. When the interval between the light emitting diode and the optical sheet is small, hot spots are generated in the regions corresponding to the respective light emitting diodes, and dark portions are generated between the adjacent light emitting diodes, which causes mura. Such a mura phenomenon is a cause of deterioration of the display quality of the liquid crystal display device due to uneven luminance.

On the other hand, enlargement of the size of the liquid crystal display increases the size of the optical sheet, causing the problem that the center of the optical sheet is projected in the gravitational direction with its own load due to its own load. To solve this problem, And functions to support the optical sheet.

An object of the present invention is to provide a backlight unit with improved illuminance uniformity by improving illuminance in a dark region and a display device including the same.

According to an embodiment of the present invention, a backlight unit includes a driving substrate, a plurality of light source portions disposed on the driving substrate, an optical sheet disposed on the plurality of light source portions, And a plurality of supports interposed between the sheets, wherein the support includes a first support portion disposed on the drive substrate and including a reflective surface on the outer surface, and a second support portion disposed on the first support portion, And the second support portion.

A display device according to an embodiment of the present invention includes the backlight unit.

According to the embodiment of the present invention, the reflection surface is formed on the support base to improve the illuminance in the dark area, thereby preventing blurring and improving illumination uniformity.

1 is an exploded perspective view illustrating a liquid crystal display device according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a backlight unit according to an embodiment of the present invention.
3 and 4 show cross-sectional views of a support according to another embodiment of the present invention.
FIG. 5 is a view for explaining an effect of improving a dark area of a backlight unit when a support according to an embodiment of the present invention is applied.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms including ordinal, such as second, first, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

In addition, the suffix "module" and " part "for constituent elements used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

1 is an exploded perspective view illustrating a liquid crystal display device according to an embodiment of the present invention. 2 is a cross-sectional view illustrating a backlight unit according to an embodiment of the present invention, and is a cross-sectional view illustrating a backlight unit of FIG. 1 taken along line A-A '. 3 and 4 are cross-sectional views of a support according to another embodiment of the present invention.

1 and 2, a liquid crystal display device includes a backlight unit 10 and a liquid crystal panel 20. [

The liquid crystal panel 20 may include a thin film transistor (TFT) substrate, a color filter substrate, and a liquid crystal layer interposed between the two substrates. The thin film transistor substrate includes a plurality of gate lines, a plurality of data lines intersecting the plurality of gate lines, and a thin film transistor (TFT) formed in the intersection region of the gate lines and the data lines.

A driving circuit unit 30 may be connected to one side of the liquid crystal panel 20.

The driving circuit unit 30 includes a printed circuit board (PCB) 31 for supplying a scanning signal to the gate line of the thin film transistor substrate and a printed circuit board 32 for supplying a data signal to the data line .

The driving circuit unit 30 is electrically connected to the liquid crystal panel 20 by a method such as a chip on film (COF), a tape carrier package (TCP) or the like.

The liquid crystal display may further include a panel guide 21 for supporting the liquid crystal panel 20 and an upper case 22 for covering the edge of the liquid crystal panel 20 and coupled to the panel guide 21.

The backlight unit 10 is coupled to the liquid crystal panel 20 and includes a bottom cover 300, a driving substrate 200, a plurality of light sources 100, at least one optical sheet 400, (500), and the like. In FIG. 1, the backlight unit 10 is shown as a direct type, but it should be understood that the embodiment of the present invention is not limited thereto. According to an embodiment of the present invention, the backlight unit 10 may be of an edge type.

The lower cover 300 may be made of metal or the like and may be provided in a box shape having an opened top. For example, the lower cover 300 may be formed by bending or curving a metal plate or the like.

The driving board 200 is accommodated in a space formed by bending or curving the lower cover 300. The lower cover 300 also functions to support the optical sheets 400 and the liquid crystal panel 20.

The driving substrate 200 has a plate shape, and a reflective layer may be formed on the driving substrate 200. The reflective layer reflects the light emitted from the light emitting diode 110 and improves the performance of the backlight unit 10.

A plurality of light source units 100 may be mounted on the driving substrate 200.

Each light source unit 100 may include a light flux control member 120 disposed to cover the light emitting device 11 and the light emitting device 110.

The light emitting device 110 is disposed on the driving substrate 200 and is electrically connected to the driving substrate 200. The light emitting device 110 emits light in accordance with a driving signal supplied from the driving substrate 200.

Each of the light emitting devices 110 operates as a point light source and an array of the light emitting devices 110 disposed at a predetermined interval on the driving substrate 200 may form a surface light source.

The light emitting device 110 may include, but is not limited to, a light emitting diode. The light emitting diode may be provided in the form of a light emitting diode package including a light emitting diode chip.

The light emitting element 110 may be irradiated with white light, or evenly divided into blue light, green light and red light.

When the light emitted from the light emitting element 110 is incident, the light flux controlling member 120 controls the light flux to improve the luminance uniformity.

The light flux controlling member 120 may be provided separately from the light emitting element 110. [ Also, the light flux controlling member 120 may be implemented as an IOL (Integrated Optical Lens) type in which the light emitting device 110 is housed, that is, a light emitting device integrated type.

The optical sheet 400 includes a diffusion sheet 410, a polarizing sheet 420, a prism sheet 430 and the like, and can be used to improve the characteristics of light passing through the optical sheet 400.

The diffusion sheet 410 directs the light incident from the light source unit 100 toward the front surface of the liquid crystal panel 20 and diffuses the light so as to have a uniform distribution over a wide range to irradiate the liquid crystal panel 20.

The polarizing sheet 420 functions to polarize the incident light obliquely incident on the polarizing sheet 420 so as to be vertically emitted. At least one polarizing sheet 420 may be disposed under the liquid crystal panel 20 to change the light emitted from the diffusion sheet 410 vertically.

The prism sheet 430 transmits light parallel to its transmission axis and reflects light perpendicular to the transmission axis.

Each supporting base 500 performs a function of supporting the optical sheet 400.

In addition, each support 500 performs a function of reflecting light, which is lost between adjacent light source portions 100, toward the optical sheet 400.

The light irradiated from the light source unit 100 can not sufficiently reach between adjacent light source units 100, so that a relatively darker dark area can be generated compared with the surroundings. The support base 500 is disposed in a region where the light loss is large between adjacent light source portions 100 so that the light that is lost between the light source portions 100 is reflected toward the optical sheet 500 so that the lost light is irradiated to the dark portions. By changing the optical path, the function of minimizing the occurrence of the dark portion and improving the illuminance in the dark portion is performed.

2, the support 500 includes a lower support 510 including a reflective surface on its outer surface, an upper support 520 supporting the optical sheet 400, and a support 500 on the drive substrate 200 (Not shown).

One side of the lower support 510 is in contact with the driving substrate 200 and may be provided in a shape of a horn having a predetermined inclination. Since the outer supporting surface 510 is formed to have an inclined outer surface, the width of the lower supporting portion 510 may gradually decrease as the distance from the driving substrate 200 increases.

The lower support 510 may have a linearly decreasing diameter as the distance from the driving substrate 200 increases. In this case, the lower supporting part 510 may include a straight section having a section perpendicular to the driving substrate 200 as shown in FIG.

In addition, the lower support 510 may have a nonlinearly decreasing diameter as the distance from the driving substrate 200 increases. In this case, the lower support 510 may include a curved section perpendicular to the driving substrate 200 as shown in FIG.

On the other hand, the lower support 510 may be formed to have a low inclination in order to reflect most of light incident on the outer surface of the lower support 510 toward the upper optical sheet 400. For example, the lower support 510 may be formed such that its outer surface is inclined at an angle of 15 to 45 degrees with respect to the driving substrate 200.

In addition, the lower support 510 may be provided with a diameter enough to reflect the light that is lost to the arm while sufficiently spaced from the light source 100. For example, the lower support 510 may have a bottom diameter in contact with the driving substrate 200, that is, a maximum diameter of 10 mm to 40 mm.

The lower support 510 may be designed to have a different height according to the maximum diameter. For example, the ratio of the maximum diameter to the height of the lower support 510 may be 1.5: 1 to 2: 1. Here, if the height of the lower support 510 is too low, the effect of improving the unevenness is reduced. On the other hand, if the height of the lower support 510 is too high, the brightness of the light source 100 Or a shadow of the upper supporter 520 may be generated.

The lower support 510 may have various shapes such as a circle, an ellipse, a triangle, a quadrangle, or the like in a horizontal cross section on the driving substrate 200.

The lower support 510 may be formed of a white or silver material capable of forming a reflective surface so that its outer surface forms a reflective surface. For example, the lower support 510 may be formed using a material such as titanium dioxide (TiO2), white polycarbonate (White PC), a milky white dye, or the like.

2, the upper support 520 is disposed on the lower support 510, and one end of the upper support 520 functions to support the optical sheet 400 in contact with the back surface of the optical sheet 400. Referring to FIG.

The upper support 520 may be formed to have a minimum diameter for supporting the optical sheet 400 to minimize the influence on the light incident on the optical sheet 400. [ For example, the upper support 520 may have a maximum diameter of 0.05 mm to 2 mm.

The upper support portion 520 may maintain a constant diameter as a whole or may gradually decrease in diameter as it approaches the optical sheet 400. [

The upper support portion 520 may have various shapes such as a circle, an ellipse, a triangle, a quadrangle, or the like in a horizontal cross section on the driving substrate 200.

The upper support portion 520 may be integrally formed with the lower support portion 510.

The upper support 520 may extend from the lower support 510, as shown in FIGS. In this case, the upper support portion 520 may be formed of the same material as the lower support portion 510.

3, the upper support 520 may be separately formed from the lower support 510 and then coupled to the lower support 510 by an adhesive member (not shown). In this case, unlike the lower support 510, the upper support 520 may be formed of a transparent material so as to minimize the influence of light from the light source 100 to the optical sheet 400. As the transparent substrate forming the upper support part 520, thermoplastic resin, UV curable resin, or the like may be used.

Referring again to FIG. 2, the fixing unit 530 functions to fix the support 500 to the driving substrate 200 and the lower cover 300. For example, the fixing unit 530 is fastened to the driving substrate 200 and the lower cover 300 in a hook manner to fix the supporting table 500 to the driving substrate 200 and the lower cover 300 .

The fixing portion 530 is integrally formed with the lower supporting portion 510 and may protrude downward from the lower supporting portion 510.

The fixing part 530 may be formed with a locking step on the outside in order to prevent the fixing part 530 from being detached after being fastened to the driving substrate 200 and the lower cover 300.

Referring to FIG. 2, the driving substrate 200 and the lower cover 300 are formed with a plurality of through holes through which the fixing portions 530 of the supporter 500 are fitted, and the fixing portions 530 are formed in the through holes And is coupled to the driving substrate 200 and the lower cover 300.

While the fixing portion 530 is fitted in the through hole formed in the driving substrate 200 and the lower cover 300, the engaging end formed on the side surface of the fixing portion 530 is gathered inward by the insertion pressure, After completely passing through the through holes formed in the cover 300, the retaining tabs 300 may be unfolded to fix the support tabs 500 to the drive substrate 200 and the lower cover 300.

FIG. 5 is a view for explaining an effect of improving a dark area of a backlight unit when a support according to an embodiment of the present invention is applied. FIG. 5 is a graph showing the illuminance distribution of a general backlight unit and a backlight unit to which the present invention is applied, The results of the experiment are shown.

FIG. 5 (a) shows the illuminance distribution of the conventional backlight unit, and FIG. 5 (b) shows the illuminance distribution of the backlight unit to which the support according to the embodiment of the present invention is applied.

Referring to FIG. 5A, it can be seen that in the case of the conventional backlight unit, the difference between the area corresponding to the lens and the illuminance at the dark area is 1763 lux, and the illuminance difference between the area corresponding to the lens and the dark area is large.

5B, when a support according to an embodiment of the present invention is applied, the difference in illuminance between the area corresponding to the lens and the illuminance at the dark area is 418 lux, which corresponds to the lens in comparison with the conventional backlight unit It can be seen that the difference in roughness between the area and the dark area is greatly reduced.

When the support according to the embodiment of the present invention is applied, the efficiency of the dark area of the backlight unit relative to the lens (efficiency at the dark area when the lens efficiency is 100%) is 70% to 80% The illuminance uniformity is improved as compared with the conventional backlight unit.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (11)

Driving substrate,
A plurality of light sources arranged on the driving substrate,
An optical sheet disposed on the plurality of light source portions, and
And a plurality of supports interposed between the driving substrate and the optical sheet to support the optical sheet,
[0028]
A first support disposed on the driving substrate and having a reflective surface on an outer surface thereof,
And a second support portion disposed on the first support portion and supporting the optical sheet.
The method according to claim 1,
Wherein the first supporting portion and the second supporting portion are inclined to one surface of the driving substrate.
3. The method of claim 2,
Wherein the first support portion has an inclination of 15 degrees to 45 degrees with respect to one surface of the driving substrate.
The method according to claim 1,
Wherein the first support has a maximum diameter of 10 mm to 40 mm.
The method according to claim 1,
Wherein the ratio of the maximum diameter to the height of the first support portion is 1.5: 1 to 2: 1.
The method according to claim 1,
And the second support portion has a maximum diameter of 0.05 mm to 2 mm.
The method according to claim 1,
Wherein the driving substrate includes a plurality of through holes,
The backlight unit according to claim 1, further comprising a fixing part extending from the first supporting part and fitted to the through hole.
The method according to claim 1,
Wherein the first support is formed using a material mixed with titanium dioxide (TiO2), white polycarbonate (White PC), or milky white dye.
The method according to claim 1,
And the first support portion and the second support portion are coupled by an adhesive member.
The method according to claim 1,
And the second support portion is formed of a transparent material.
A display device comprising a backlight unit according to any one of claims 1 to 10.

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