KR20190122278A - Light diffusion structure and backlight unit including the same - Google Patents

Abstract

A backlight unit is disclosed. The backlight unit comprises: a light guide plate; a light source array in which light sources are arranged to be spaced apart by a predetermined distance on a circuit board, and disposed on one side of the light guide plate; and a light diffusion structure which is disposed on the light source array to be placed on the light source array, faces one side of the light guide plate, and includes a light source accommodating unit accommodating the light source, and a light direction switching unit connected to the light source accommodating unit to be disposed above the light source and including at least one reflective surface being convex in the direction of the light source to face light emitted from the light source. The light diffusion structure has an array structure in which the light source accommodating unit and the light direction switching unit are continuously arranged in the longitudinal direction of the light source accommodating unit. The reflective surface of the light direction switching unit is a first reflective surface reflecting the light emitted from the light source. One surface of the light source accommodating unit facing the first reflective surface is a second reflective surface reflecting light, reflected from the first reflective surface, toward the light guide plate.

Description

LIGHT DIFFUSION STRUCTURE AND BACKLIGHT UNIT INCLUDING THE SAME}

The present invention relates to a backlight unit, and more particularly to a backlight unit that provides a high brightness backlight with a small number of light sources.

In general, a liquid crystal display device, which is a kind of light receiving type flat panel display, does not emit light by itself and forms an image by injecting light from the outside. To this end, a backlight unit is installed on the back of the liquid crystal display to irradiate light. This backlight unit is used not only for liquid crystal display devices but also for surface light source devices such as lighting signs.

The backlight unit is classified into a direct light type and an edge light type according to the arrangement of the light sources. The direct emission type is a method in which a lamp installed directly below the liquid crystal panel directly irradiates light directly onto the liquid crystal panel. In the edge emitting type, a lamp installed at an edge of a light guide panel (LGP) irradiates light and transmits the irradiated light to the liquid crystal panel through the light guide plate.

The edge emitting type can use a line light source and a point light source as a light source. Representative light sources include a cold cathode fluorescent lamp (CCFL) in which electrodes at both ends are installed in a tube. As the point light source, there is a light emitting diode (LED).

CCFLs have the advantage of being able to emit strong white light, achieve high brightness and high uniformity, and enable large area designs. However, this CCFL is operated by a high frequency AC signal and has a narrow operating temperature range. In terms of brightness and uniformity, LEDs

Poor performance compared to CCFL. However, this LED has the advantage of being operated by DC signal, long life, wide operating temperature range, and thinness.

1 is a schematic cross-sectional view of a conventional general edge-emitting backlight unit.

Referring to FIG. 1, in the conventional backlight unit, a light source 20 is disposed at a side edge of the light guide plate 10 spaced apart from a light incident end surface 11 of the light guide plate 10 by a predetermined distance. In this structure, the light source 20 emits light toward the light incident end face 11 of the light guide plate 10. In this case, in the arrangement of the light source 20, the radiation angle of the light source 20 and the light incident distance from which the light is incident from the light source 20 to the light guide plate 10 are taken into consideration, and in order to increase the luminance of the light guide plate 10, the light source ( It is common to narrow the distance at which light is incident from the light guide plate 10 to the light guide plate 10, and in this case, the number of the light sources 20 increases.

Therefore, the conventional backlight unit needs a large number of light sources 20 to increase the brightness of the light guide plate 10, which acts as a factor of increasing the manufacturing cost of the backlight unit.

Accordingly, an object of the present invention is to provide a backlight unit capable of providing a backlight having high brightness even with a small number of light sources, preventing variations in light uniformity and brightness of the backlight unit, and increasing heat dissipation effect.

Another object is to provide a backlight unit so that light leakage can be prevented.

The backlight unit according to an embodiment of the present invention for solving the above problems is a light guide plate; A light source array arranged on the circuit board such that light sources are spaced apart from each other by a predetermined distance, and disposed on one side of the light guide plate; And disposed on the light source array so as to lie on the light source array so as to face one side of the light guide plate and connected to the light source receiving portion and the light source receiving portion which is connected to the light source receiving portion and convex toward the light source. And a light diffusing structure including a light turning part including at least one reflective surface facing the light emitted from the light source, wherein the light diffusing structure includes the light source receiving part and the light turning part having a longitudinal direction of the light source receiving part. Having an array structure arranged in succession, the reflecting surface of the light turning portion is a first reflecting surface reflecting light emitted from the light source, and one surface of the light source receiving portion facing the first reflecting surface is the first half; And a second reflection that reflects light reflected from a slope so that the light is directed toward the light guide plate. It is done.

In one embodiment, the light source receiving portion, the base portion extending in a predetermined length, the light source is disposed in the center; And a sidewall part disposed perpendicular to the base part and parallel to a length direction of the base part, wherein the light direction switching part may be concave in the inward direction of the sidewall part from the sidewall part.

In one embodiment, the base unit, the light source arrangement of the hole structure for receiving the light source; And a light guide plate stopper part extending higher than the height of the light source as an end of the base part extending left and right from the light source arrangement part and corresponding to one side of the light guide plate to support the light guide plate. The side surface of the light guide plate stopper portion may be covered.

In one embodiment, the base portion may have a cross-sectional shape bent in a bow shape.

In an embodiment, the length of the light source accommodating part may be greater than or equal to a pitch between light sources on the light source array.

In example embodiments, the width of the light diffusing structure may be equal to or greater than the thickness of the light guide plate to be 0.2 mm or less than the thickness of the light guide plate.

According to the backlight unit according to the present invention, it is possible to provide a backlight having high brightness even with a small number of light sources, to prevent a change in the uniformity and brightness of the light of the backlight unit, and to increase the heat dissipation effect.

In addition, there is an advantage that the light leakage phenomenon can be prevented.

1 is a cross-sectional view illustrating a conventional backlight unit.
2 is a perspective view illustrating a backlight unit according to an embodiment of the present invention.
3 is an enlarged perspective view illustrating the light diffusing structure illustrated in FIG. 2.
4 is a perspective view of the light diffusing structure viewed from below the light diffusing structure shown in FIG. 2.
5 is a cross-sectional view illustrating an assembled state of the backlight unit illustrated in FIG. 1.
FIG. 6 is a cross-sectional view illustrating a path in which light from a light source of a backlight unit according to an embodiment of the present invention is incident on a light guide plate.
7 is a perspective view illustrating another example of the light diffusing structure illustrated in FIG. 2.

Hereinafter, a light diffusing structure and a backlight unit including the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific form disclosed, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements. In the accompanying drawings, the dimensions of the structures are shown in an enlarged scale than actual for clarity of the invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the 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 first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, 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. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

The present invention discloses a light diffusing structure and a backlight unit including the same. Since the light diffusion structure includes the backlight unit, the light diffusion structure will be described in detail in the following description of the backlight unit.

2 is a perspective view illustrating a backlight unit according to an exemplary embodiment of the present invention, FIG. 3 is an enlarged perspective view of the light diffusing structure shown in FIG. 2, and FIG. 4 is a perspective view of the light diffusing structure shown in FIG. 2. It is a perspective view of the light-diffusion structure seen from below.

2 to 4, a backlight unit according to an embodiment of the present invention includes a light guide plate 100, a light source array 200, and a light diffusion structure 300.

The light guide plate 100 guides the light incident from the light source array 200 and the light diffusion structure 300 toward the liquid crystal panel of the display.

The light source array 200 includes a plurality of light sources 220 arranged on the circuit board 210 and spaced apart from each other by a predetermined distance on the circuit board 210. The light source 220 may be an LED. For example, the LED may be CSP 1313 PKG.

The light diffusing structure 300 broadly spreads an irradiation range of light emitted from the light source 220 of the light source array 200. The light diffusing structure 300 includes a light source accommodating part 310 and a light direction changing part 320, and the light source accommodating part 310 and the light direction changing part 320 extend in the longitudinal direction of the light source accommodating part 310. It has an array structure arranged in series. The number of the light source accommodating part 310 and the light direction changing part 320 is the same as the number of the light sources 220 of the light source array 200.

The light source accommodating part 310 extends to a predetermined length and accommodates a light source in the middle of the length. The light source accommodating part 310 includes a base part 311 and a side wall part 312.

The base 311 extends to a predetermined length, and a light source 220 accommodated in the light source accommodating part 310 is disposed at the center thereof. The base 311 includes a light source arrangement 3111 and a light guide plate stopper 3112. The light source arrangement 3111 has a hole structure for accommodating the light source 220, and the light guide plate stopper portion 3112 is an end of the base portion 311 extending left and right from the light source arrangement 3111. Extends higher than). The shape of the base portion 311 is not particularly limited, but preferably has a cross-sectional shape that is bent in a bow shape. The length of the base 311 may have a length greater than or equal to the pitch between the light sources 220 on the light source array 200. For example, the length of the base 311 may be equal to the pitch between the light sources 220.

The side wall portion 312 is disposed to be perpendicular to the base portion 311 and parallel to the longitudinal direction of the base portion 311. The side wall portion 312 covers side surfaces of the light source arrangement 3111 and the light guide plate stopper 3112. The height of the sidewall part 312 may have a height greater than or equal to the height of the light guide plate stopper part 3112 of the base part 311.

The light source accommodating part 310 corresponds to one side surface of the light guide plate 100 on the light source array 200. For example, the light source accommodating part 310 may correspond to a lower thickness surface (hereinafter, referred to as a light incident end surface 110) extending laterally among four thickness surfaces of the light guide plate 100. In this case, the light guide plate stopper 3112 supports the light guide plate 100 to keep the light incident end surface 110 of the light guide plate 100 spaced apart from the light source 220.

The light turning part 320 reflects a part of the light emitted from the light source 220 toward the inner surface of the light source accommodating part 310. To this end, the light direction switching unit 320 is connected to the light source receiving unit 310 is disposed above the light source 220, at least one reflective surface convex toward the light source 220 facing the light emitted from the light source 321. The light turning part 320 is recessed in an inner direction of the side wall part 312 at an upper end of each side wall part 312 of the light source accommodating part 310. The surface not parallel to the sidewall portion 312 in the concave shape is the reflective surface 321.

There is no particular limitation on the shape of the light turning part 320, and any shape may be used as long as the reflective surface 321 may reflect light toward the left and right sides of the light source accommodating part 310. For example, the light turning unit 320 may be provided as a reflective surface 321 to be concave to include one surface of an arc shape or two surfaces adjacent to each other.

For example, as illustrated in FIG. 1, the light direction switching unit 320 may be concave in an inverted triangle shape when the surface parallel to the side wall part 312 is faced in a concave shape. In this case, two surfaces that are adjacent to each other symmetrically become the reflecting surface 321.

The material of the light diffusion structure 300 is not particularly limited, and may be made of stainless steel or aluminum, which is a metal, in order to increase the heat radiation effect. The inner surface of the light source accommodating part 310 may be mirror polished and silver plated to increase reflection efficiency of light on the reflective surface.

In addition, the width of the light diffusion structure 300 may be equal to the thickness of the light guide plate 100 or greater than 0.2 mm or less than the thickness of the light guide plate 100.

The light diffusion structure 300 may further include a light guide plate holder 330.

The light guide plate holder 330 is disposed on the left and right sides of the light direction switching unit 320 to be parallel to the longitudinal direction of the light source accommodating part 310, and is greater than the height of the light guide plate stopper part 3112 from the upper end of the light source accommodating part 310. It extends high. For example, as shown in FIG. 3, the LGP holder 330 may be provided only in the direction of one sidewall portion 312 of two sidewall portions 312 facing each other. As another example, as illustrated in FIG. 7, the LGP holder 330 may be provided in both sidewall portions 312. 7 is a perspective view illustrating another example of the light diffusing structure illustrated in FIG. 2.

The light guide plate holder 330 allows the light guide plate 100 to be easily positioned at the upper end of the light diffusion structure 300 when the light diffusion structure 300 is disposed to correspond to the light incident end surface 110 of the light guide plate 100. That is, when the at least one surface perpendicular to the light incident end surface 110 of the light guide plate 100 is brought into close contact with the inner surface of the light guide plate holder 330, the light diffusion structure 300 is connected to the light incident end surface 110 of the light guide plate 100. It may correspond exactly, and the light guide plate 100 may be easily located at the upper end of the light diffusing structure 300.

Hereinafter, a process in which light is incident on the light guide plate of the backlight unit according to an exemplary embodiment of the present invention will be described with reference to FIGS. 5 and 6. 5 is a cross-sectional view illustrating an assembly state of the backlight unit illustrated in FIG. 1, and FIG. 6 is a cross-sectional view illustrating a path through which light from a light source of a backlight unit according to an exemplary embodiment is incident on a light guide plate.

5 and 6, the light of the light source 220 is irradiated to the light incident end surface 110 side of the light guide plate 100. In this case, a part of the light is directly incident on the light incident end surface 110 through the open upper portion of the light diffusing structure 300, and the other part is irradiated toward the light direction changing unit 320 of the light diffusing structure 300.

A part of the light irradiated toward the light turning part 320 is reflected from the reflecting surface 321 of the light turning part 320 and proceeds toward the left and right sides of the light source accommodating part 310. The light propagated to the left and right sides of the light reflected by the inner surface of the base portion 311 proceeds toward the light guide plate 100 and is incident on the light incident end surface 110 of the light guide plate 100.

The reflective surface 321 of the light turning part 320 becomes the first reflective surface and the inner surface of the base 311 of the light source accommodating part 310 becomes the second reflective surface according to the light propagation path.

Using the backlight unit according to an embodiment of the present invention has the following advantages.

First, a part of the light irradiated from the light source 220 is not directly incident to the light guide plate 100 but is diverted so as to travel widely to the left and right sides of the light source 220 through the first reflective surface of the light direction switching unit 320. Since the progress of the light incident on the light guide plate 100 is changed from the second reflective surface opposite to the first reflective surface to be incident to the light guide plate 100, the light irradiated from one light source 220 is applied to the light guide plate 100. The light is incident on the entire light incident end surface 110 of the light guide plate 100 even with a small number of light sources 220, thereby reducing the number of light sources 220 used in the backlight unit. There is an advantage to this. Therefore, there is an advantage that can provide a high brightness backlight with only a small number of light sources.

Second, the light diffusing structure 300 is provided at the left and right ends of the light source accommodating part 310 and has a light incident end surface of the light guide plate 100 by a light guide plate stop cloth part corresponding to the light incident end surface 110 of the light guide plate 100. Since the 110 is kept spaced apart from the light source 220, the distance from which the light emitted from the light source 220 is reflected to the first reflecting surface and the second reflecting surface is constant, and thus the illuminance plate 100 is always constant. Of light may be incident, so that a change in uniformity and brightness of light of the backlight unit is prevented.

Third, since the light diffusion structure 300 accommodates the light source 220 therein, the light diffusion structure 300 may radiate heat to heat generated by the light source 220, thereby increasing the heat radiation effect of the backlight unit.

Fourth, when the light guide plate 100 and the light diffusing structure 300 are disposed to correspond to each other by the light guide plate holder 330 of the light diffusing structure 300, the light diffusing structure 300 has a light incident end surface of the light guide plate 100. The light guide plate 100 may be easily positioned at the upper end of the light diffusion structure 300. In addition, the light guide plate holder 330 extends higher than the height of the light guide plate stopper 3112 corresponding to the light incident end surface 110 of the light guide plate 100. By covering the boundary between the upper end of the 310, it is possible to prevent the light incident on the light guide plate 100 from leaking between the boundary between the light incident end surface 110 of the light guide plate 100 and the upper end of the light source receiving portion 310. . Therefore, the light guide plate holder 330 has an advantage of preventing light leakage from the backlight unit.

Reference numeral 411 of FIG. 5 denotes a first optical sheet, and 412 denotes a second optical sheet. The first optical sheet 411 and the second optical sheet 412 are stacked on one surface of the light guide plate 100. The first optical sheet 411 and the second optical sheet 412 are sheets for improving the light efficiency. The first optical sheet 411 and the second optical sheet 412 increase the luminance by converting photometry into front light and collecting light spreading in all directions.

Reference numeral 500 in FIG. 5 denotes a reflective sheet. The reflective sheet 500 is stacked on the other side of the light guide plate 100, that is, on the opposite side to the surface on which the first optical sheet 411 and the second optical sheet 412 are stacked, and the light incident on the light guide plate 100. Prevent loss.

Reference numeral 600 in FIG. 5 denotes a frame. The frame 600 is coupled to all sides of the light guide plate 100 to accommodate and fix each component of the backlight unit.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention should not be limited to the embodiments set forth herein but should be construed in the broadest scope consistent with the principles and novel features set forth herein.

Claims (11)

A light source accommodating part extending in a predetermined length and accommodating a light source in the center of the length; And
A light direction changer connected to the light source accommodating part and disposed above the light source and including at least one reflective surface convex toward the light source and facing light emitted from the light source,
The light source accommodating part and the light direction changing part have an array structure which is continuously arranged in the longitudinal direction of the light source accommodating part
The reflecting surface of the light turning part is a first reflecting surface reflecting light emitted from the light source, and one surface of the light source accommodating part facing the first reflecting surface reflects light reflected from the first reflecting surface. 2 reflective surfaces,
Light diffusing structure for backlight unit. The method of claim 1,
The light source receiving portion,
A base portion extending to a predetermined length and having the light source disposed therein; And
It includes a side wall portion disposed perpendicular to the base portion and parallel to the longitudinal direction of the base portion,
The light direction switching unit is characterized in that it is provided concave in the inward direction of the side wall portion from the side wall portion,
Light diffusing structure for backlight unit. The method of claim 2,
The base portion,
A light source arranging unit having a hole structure for receiving the light source; And
A light guide plate stopper portion extending higher than the height of the light source as an end of the base portion extending left and right from the light source arrangement portion;
The side wall portion covers the side of the light source arrangement portion and the light guide plate stopper portion,
Light diffusing structure for backlight unit. The method of claim 3,
The base portion has a bow-shaped cross-sectional shape, characterized in that
Light diffusing structure for backlight unit. The method of claim 1,
The length of the light source receiving portion is characterized in that more than the pitch between the light source disposed along the longitudinal direction of the array structure,
Light diffusing structure for backlight unit. Light guide plate;
A light source array arranged on the circuit board such that light sources are spaced apart from each other by a predetermined distance, and disposed on one side of the light guide plate; And
Disposed on the light source array so as to lie on the light source array, facing one side of the light guide plate; A light diffusing structure comprising a light redirecting portion comprising at least one reflective surface facing the light emitted from the light source,
The light diffusing structure has an array structure in which the light source accommodating part and the light direction changing part are continuously arranged in the longitudinal direction of the light source accommodating part,
The reflecting surface of the light turning part is a first reflecting surface reflecting light irradiated from the light source, and one surface of the light source accommodating part facing the first reflecting surface reflects the light reflected from the first reflecting surface. A second reflective surface that faces the light guide plate,
Backlight unit. The method of claim 6,
The light source receiving portion,
A base portion extending to a predetermined length and having the light source disposed therein; And
It includes a side wall portion disposed perpendicular to the base portion and parallel to the longitudinal direction of the base portion,
The light direction switching unit is characterized in that it is provided concave in the inward direction of the side wall portion from the side wall portion,
Backlight unit. The method of claim 7, wherein
The base portion,
A light source arranging unit having a hole structure for receiving the light source; And
A light guide plate stopper part extending from a height of the light source as a distal end of the base part extending left and right from the light source arrangement part and corresponding to one side of the light guide plate to support the light guide plate;
The side wall portion covers the side of the light source arrangement portion and the light guide plate stopper portion,
Backlight unit. The method of claim 8,
The base portion has a bow-shaped cross-sectional shape, characterized in that
Backlight unit. The method of claim 6,
The length of the light source receiving portion is characterized in that more than the pitch between the light source on the light source array,
Backlight unit. The method of claim 6,
The width of the light diffusion structure is characterized in that the same as the thickness of the light guide plate or greater than 0.2mm or less than the thickness of the light guide plate,
Backlight unit.

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