KR20180087116A - Luminous flux control member and back light unit using the same - Google Patents

Abstract

Provided is a luminous flux control member capable of uniformly diffusing light emitted from a light source. The luminous flux control member includes a first main surface having a concave light entering surface on a reference optical axis of a light emitting element, a second main surface having a concave part on the reference optical axis on the back surface of the first main surface, and a light intensity adjusting sheet formed on at least the second main surface around the concave part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a luminous flux control member and a backlight unit using the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light flux control member and a backlight unit, and more particularly, to a light flux control member having a large light diffusion area and a backlight unit using the same.

Unlike an OLED capable of self-emission, a display that can not self-emit light such as an LCD is provided with a light source using a backlight unit located on the back of the display.

A backlight unit (BLU) is a component that constitutes a liquid crystal display together with a liquid crystal panel, a driver IC, a substrate (e.g., PCB) Which is positioned below the liquid crystal panel and irradiates uniform planar light to enable the image of the liquid crystal display (LCD) to be recognized.

The backlight unit may include a cylindrical fluorescent lamp such as a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode discharge lamp (EEFL) Light-emitting diodes (LEDs) and electroluminescence (EL) devices are used as light sources. In recent years, LEDs are increasingly used as a light source for reasons of environment friendliness, energy saving, life span and durability.

The backlight unit using the LED is divided into an edge type and a direct type according to the installation position of the LED light source.

The edge type backlight unit receives light emitted from the LED on a reflector sheet that reflects the light exiting to the lower surface of the light guide panel and reflects the light back into the light guide member, A light guide member for uniformly distributing light over a screen display region of a liquid crystal display (LCD) through a pattern having a plurality of LEDs, and a substrate (e.g., a PCB) having a plurality of LEDs on both sides of the light guide member A diffuser sheet for uniformly diffusing light emitted from the light guiding member in a predetermined direction and scattering light over the entire surface of the light guiding member is provided in the upper portion of the light guiding member, A prism sheet for increasing the luminance by refracting and condensing the light emitted from the prism sheet, Is provided with a protective sheet (Protect Sheet) which protects the prism sheet and diffuses the light to widen the viewing angle narrowed by the prism sheet. The reflective sheet, the light guide member, the substrate (e.g., PCB), the diffusion sheet, the prism sheet, and the protective sheet installed as described above are fixed by a mold frame serving as a case.

Alternatively, the direct-type backlight unit may include a reflective sheet on a substrate (e.g., a PCB) having a plurality of LED arrays including a plurality of LEDs, a light guide member, a diffusion sheet, a prism sheet, A protective sheet is sequentially installed. The substrate (e.g., PCB), the reflective sheet, the light guide member, the diffusion sheet, the prism sheet, and the protective sheet installed as described above are fixed by a mold frame serving as a case.

Meanwhile, since the direct-type backlight unit is provided under the light guide member, the LED array can be local-dimmed according to the light irradiation area of the display area of the liquid crystal display (LCD) The power consumption efficiency can be increased.

However, since the direct-type backlight unit has an LED positioned at a position directly under the light-irradiated area in the screen display area of the liquid crystal display (LCD), the point where the LED is positioned in the light- A white-spot phenomenon occurs.

Therefore, the above direct-type backlight unit has an air gap (hereinafter referred to as " LED ") for diffusing light between the LED and the light guide member to suppress the above-mentioned white- spot phenomenon and diffuse the light emitted from the LED sufficiently uniformly Air gap, and the thickness of the light guiding member must be increased, and there is a limitation in reducing the thickness of the backlight unit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light flux control member capable of uniformly diffusing light emitted from a light source to suppress white spot phenomenon and a backlight unit using the same.

In order to solve the above problems, the present invention provides a light flux control member capable of uniformly diffusing light emitted from a light source.

The light flux controlling member includes a first main surface having a concave light incident surface on a reference optical axis of the light emitting element, a second main surface having a concave portion on the reference optical axis on the back surface of the first main surface, And a light amount adjusting sheet formed on the second main surface.

In one embodiment of the present invention, the light quantity adjusting sheet covers the periphery of the recess and the upper portion of the recess.

In one embodiment of the invention, in the cross-section through the reference optical axis, the recess includes both side walls and a horizontal plane between the side walls

In one embodiment of the present invention, in the cross section passing through the reference optical axis, the concave portion includes a center having an inclination of zero and a curved surface increasing in inclination as the distance from the center increases.

In one embodiment of the present invention, in the cross section passing through the reference optical axis, the concave portion includes a curved surface whose center is inclined toward the light source with increasing inclination from the edge to the center.

In one embodiment of the present invention, the light amount adjusting sheet is formed on the second main surface around the concave portion and the concave portion is opened, further comprising a reflective coating layer formed on the concave portion.

According to an embodiment of the present invention, the concave portion may include a first concave portion having a center of inclination of 0 and a curved surface increasing in inclination as the distance from the center increases, a horizontal plane around the first concave portion, And a second concave portion having a curved surface whose inclination increases with increasing distance from the stepped surface.

In one embodiment of the present invention, the light amount adjusting sheet further includes a reflective coating layer formed on the first concave portion, wherein the light amount adjusting sheet is disposed on the second main surface, the second concave portion, And the first concave portion is opened.

In one embodiment of the present invention, the light amount adjusting sheet passes through a part of the light that has passed through the incident surface and reaches the second main surface, and reflects a part of the light to the first main surface.

According to an aspect of the present invention, there is provided a backlight unit. The backlight unit includes a substrate, a light emitting element mounted on the substrate, and a light flux control member covering the light emitting element.

In one embodiment of the present invention, the light flux control member includes a first main surface having a concave light incident surface on a reference optical axis of the light emitting element, and a second main surface having a concave on the reference optical axis, And a light amount adjusting sheet formed on at least the second main surface around the concave portion.

In an embodiment of the present invention, the backlight unit may include a plurality of light emitting elements disposed on a substrate, a light flux control member disposed on each light emitting element, and a plurality of light flux control members arranged in a matrix on the substrate have.

In one embodiment of the present invention, the backlight unit includes a plurality of light emitting elements disposed on the substrate, a light flux control member disposed on the plurality of light emitting elements, and a plurality of light flux control members disposed on the substrate, Lt; / RTI >

According to the present invention, the light emitted from the region adjacent to the reference optical axis is reflected to the inside of the light flux controlling member and emitted through the peripheral light emitting surface, thereby diffusing the light of the light source to disperse the maximum light amount in the vicinity of the reference light, .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view for explaining a light flux control member according to an embodiment of the present invention; FIG.
1B is a sectional view taken along line A-A 'in FIG. 1;
2 is a diagram for explaining light diffusion in a light flux control member according to an embodiment of the present invention;
FIGS. 3 to 5 are cross-sectional views illustrating a light flux control member according to another embodiment of the present invention;
6 is a plan view for explaining a light flux control member according to another embodiment of the present invention;
7A and 7B are plan views illustrating a light flux control member arranged in a backlight unit according to an embodiment of the present invention;
8A is a plan view for explaining a light flux control member according to another embodiment of the present invention;
FIG. 8B is a sectional view taken along line A-A 'of FIG. 8; FIG.
9 is a plan view for explaining a light flux control member according to another embodiment of the present invention;
10 is a cross-sectional view for explaining another embodiment of the light flux control pattern of the light flux control member according to the present invention.

FIG. 1A is a plan view for explaining a light flux control member according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line A-A 'in FIG.

1, a light flux control member 100 for a direct-lighting type backlight unit according to the present invention includes a first main surface 32 having a concave light incident surface 32s on a reference optical axis of a light emitting device 20, A light guide member 30 including a second main surface 34 having a concave portion 36b on the reference optical axis on the back surface of the first main surface 32; And a light amount adjustment sheet 50 formed on the light guide plate 34.

A predetermined incidence hole 36a is formed between the light emitting device and the first main surface 32 at the reference optical axis of the first main surface 32 and the periphery thereof.

The cross section of the light incident surface 32s taken along the reference optical axis may be parabolic or hemispherical. In addition, the inclination may gradually increase in the negative direction from the reference optical axis in the vicinity of the reference optical axis, and the inclination may gradually increase in the positive direction around the reference optical axis, And may have a convex shape at the center of the hole 36a.

A plurality of light flux control patterns 38 are formed on the first main surface. The light flux control patterns 38 may be concentrically formed around the reference optical axis. The cross section of the light flux control patterns 38 may have various shapes such as a triangular groove, a square groove, an arc, an arch, and a parabola. In addition, the light flux control patterns 38 are not limited to being arranged concentrically, but may have various shapes such as circular dots, square dots, lattices, spots, spirals, and woven patterns.

The light guide member 30 may be made of PMMA (Poly Methyl Methacrylate) or PC (Poly Carbonate).

For example, the light guide member 30 may be made of PMMA (Poly Methyl Methacrylate) or PC (haze) having a total light transmittance (Tt) of 90% or more as measured by the JIS K7361-1 measurement method and a haze of less than 0.5% Poly Carbonate).

The light amount adjusting sheet 50 is formed on the first main surface 34 around the concave portion 36b. The light amount adjusting sheet 50 may be adhered to the first main surface 34, or may be coated with a paint or a resin. The light amount adjusting sheet 50 may be formed on the first main surface 34 with at least an opening exposing at least a part of the concave portion 36b and the edge may be formed in a wavy or serrated Pattern. The light amount adjustment sheet 50 may be a semi-transparent material that can transmit only a part of light, and may be a dispersion of diffusion particles in a transparent substrate or a white transparent sheet.

The concave portion 36b is composed of a light reflection surface 34s having a center of inclination of 0 on the cross section passing the reference optical axis and a curved surface increasing in inclination as the distance from the center increases, The reflective coating layer 60 may further include a reflective coating layer 60 thereon. For example, the reflective coating layer 60 may be formed on the concave portion 36b near the reference optical axis. The light reaching the reflective coating layer 60 is partially transmitted and partially reflected at the interface between the reflective coating layer 60 and the reflective surface 34s and returned to the inside of the light guide member 30. [

The light flux controlling member 100 according to the present invention may be disposed on the substrate 10 and an adhesive layer or an adhesive sheet may be interposed between the light guide member 30 and the substrate 10, (30) and the substrate (10) can be combined.

The light flux control member 100 may be disposed on the substrate 10 such that the light emitting device is mounted on the substrate and the incident hole 36a is positioned on the reference optical axis of the light emitting device.

However, the light flux control member 100 may be bonded to the substrate 10 by other fastening means without being bonded or attached to the substrate 10.

The light guide member 30 may have a rectangular planar shape, and may have a shape in which each corner portion is partially removed, for example, a square, a triangle, or a circular arc shape.

2 is a view for explaining light diffusion in a light flux control member according to an embodiment of the present invention.

Referring to FIG. 2, since the light emitted from the light emitting device has the maximum amount of light in the vicinity of the reference optical axis, white spots can only occur at the center of the reference optical axis of the light emitting device. However, according to the present invention, by forming the concave light reflection surface 34s on the first main surface around the reference optical axis, the strong light on the reference optical axis main surface can be dispersed to the surroundings to suppress the occurrence of white spots.

The light r1 emitted from the light emitting device is incident into the light guide member 30 through the light incident surface 32s and part of the light r1 is reflected by the light reflection surface 34s, (34). ≪ / RTI > Of course, in order for the light emitted from the light emitting device to be totally reflected on the light reflection surface 34s, the angle between the normal to the light reflection surface 34s and the incident light must be equal to or greater than a critical angle. That is, since the angle of incidence of the light reaching the light reflection surface 34s may be greater than the critical angle when the light emitted from the light emitting device 20 is not less than the predetermined angle?, The light is emitted above the angle? (34s) is reflected and emitted to the outside through the second main surface (34). At this time, the light r11 having a critical angle or more from the second main surface 34 of the light reaching the second main surface 34 is returned to the inside of the light guide member 30 and reflected from the first main surface 32 And can be discharged to the outside. Since a plurality of light flux control patterns 38 are provided on the first main surface 32, a part r12 of light reaching the first main surface 32 is refracted or reflected by the light flux control pattern 38, And can be returned to the inside of the guide member 30.

The light adjustment sheet 50 diffuses light to transmit light, and the light passing through the light amount adjustment sheet 50 is uniformly diffused to suppress glare.

The light emitted from the light emitting device 20 at an angle smaller than the angle θ may be refracted by the light reflecting surface 34s to be emitted to the outside and a part of the light may be returned to the inside of the light guide member 30. [ The reflective coating layer 60 may be selectively formed to suppress an excessive amount of light transmitted through the light reflecting surface 34s and emitted to the outside.

The light r2 reflected from the light reflecting surface 34s returns to the inside of the light guide member 30 and is reflected by the first main surface 32 to pass through the inside of the light guide member 30, (34). ≪ / RTI > The light passing through the light amount adjusting sheet 50 among the light emitted through the second main surface 34 can be diffused evenly. The light r21 reflected by the second main surface 34 may be reflected by the first main surface 32 and may be emitted to the outside through the light guide member 30. [

Some light passing through the inside of the light guide member 30 may be refracted or reflected by the light flux control pattern 38 and may be emitted to the outside through the second main surface 32 in various directions.

As described above, according to the present invention, the light propagation direction of the light emitting element having the maximum light amount near the reference optical axis is dispersed by using the light flux control member 100, thereby suppressing white spots in the vicinity of the reference optical axis, It can be discharged to the outside.

3 to 5 are sectional views for explaining a light flux control member 100 according to another embodiment of the present invention.

3, the concave portion 36b of the light flux control member 100 according to the present invention includes a first concave portion having a center with a zero inclination and a curved surface 34sb whose inclination increases with increasing distance from the center, A second concave portion having a horizontal surface around the first concave portion and a step surface 34st at the horizontal surface edge and a curved surface 34sa whose inclination increases as the distance from the step surface is increased.

The light amount adjustment sheet 50 is formed on the second main surface 34 around the concave portion 36b. The light amount adjusting sheet 50 may extend over the concave portion 36b to cover a part of the concave portion 36b.

A reflective coating layer 60 may be further formed on the curved surface 34sb of the first concave portion of the concave portion 36b. The light amount adjustment sheet 50 may extend to the upper portion of the curved surface 34sa of the second concave portion.

According to this embodiment, since the light directed toward the second main surface 34 in the vicinity of the reference optical axis has a large incidence angle on the normal basis, the total reflection probability is high and the light incident on the second major surface 34 on the outer side has a normal reference incidence angle So that it is refracted at the curved surface 34sa of the second obtuse portion and is emitted to the outside. That is, the light in the vicinity of the reference optical axis having a large amount of light is mainly scattered back to the inside of the light guide member 30, and the ambient light having a small light amount mainly passes through the light guide unit 30 and is emitted to the outside, Can be dispersed. The light passing through the curved surface 34sa of the second concave portion can be evenly dispersed evenly through the light amount adjusting sheet 50 extending to the upper portion of the concave portion.

Referring to FIG. 4, the concave portion 36b of the light flux control member 100 according to the present invention may have a curved surface 34s whose inclination increases toward the center from the edge, and whose center converges toward the light source.

The curved surface 34s has a large slope in the vicinity of the reference light source and a gentler slope toward the periphery. Therefore, the light in the vicinity of the reference optical axis having a large amount of light has a high total reflection probability because the angle of incidence on the normal line of the curved surface 34s is large, and the incidence angle decreases toward the periphery, resulting in a low total reflection probability. Therefore, the amount of light in the vicinity of the reference optical axis can be dispersed to suppress white spots. In addition, a reflective coating layer 60 may be formed on the curved surface 34s to uniformly disperse the light passing through the concave portion 34b.

5, the concave portion 36b of the light flux control member 100 according to the present invention has a light reflecting surface 34s including a side surface and a horizontal surface between the side walls in a cross section passing the reference optical axis ). It is possible to disperse the light in the vicinity of the reference optical axis having a large light amount back into the light guide member 30 by including the reflective coating layer 60 on the light reflecting surface 34s.

6 is a plan view for explaining a light flux control member according to another embodiment of the present invention.

The light flux control member 100 according to the present invention has a symmetrical structure about one reference optical axis as shown in FIG. That is, one light flux controlling member 100 is disposed on one light emitting element to uniformly disperse light.

Referring to FIG. 6, the light flux controlling member 200 according to the present invention may have a structure in which only one light flux controlling member 200 is disposed on a plurality of light emitting devices. For example, four light flux controlling members 100 having a structure as shown in Fig. 1A may be combined. However, the present invention is not limited to this, and the light flux controlling member 200 according to the present invention may be of a combination of various numbers of structures of FIG. 1, such as two, three, six, eight, Or they may be arranged in the horizontal or vertical direction or linearly arranged.

7A and 7B are plan views illustrating a light flux control member arranged in a backlight unit according to an embodiment of the present invention.

7A and 7B, the backlight unit 300 and 400 according to the present invention include a plurality of light flux control members 100 and 200 arranged in a matrix on a substrate to emit light of light emitting devices mounted on the substrate It can be evenly dispersed. Since the light around the reference optical axis having a high light intensity is uniformly dispersed around and emitted upward by the light flux control members 100 and 200 according to the present invention, Or the spacing between the displays can be minimized.

FIG. 8A is a plan view for explaining a light flux control member according to an embodiment of the present invention, and FIG. 8B is a sectional view taken along line A-A 'in FIG.

8A and 8B, a light flux control member 600 for a direct-lighting type backlight unit according to the present invention includes a first main surface 632 having a concave light incident surface 632s on a reference optical axis of the light emitting device 620, A light guide member 630 including a second main surface 634 having a concave portion 636b on the reference optical axis on the back surface of the first main surface 632; And a light amount adjusting sheet 650 formed on the two main surfaces 634. [

A predetermined incidence hole 636a is formed between the light emitting device and the first main surface 632 at the reference optical axis of the first main surface 632 and the periphery thereof.

The cross section of the light incident surface 632s taken along the reference optical axis may be parabolic or hemispherical. In addition, the inclination may gradually increase in the negative direction from the reference optical axis in the vicinity of the reference optical axis, and the inclination may gradually increase in the positive direction around the reference optical axis, And may have a convex shape at the center of the hole 636a.

A plurality of light flux control patterns 638 are formed on the first main surface. The light flux control patterns 638 may be concentrically formed around the reference optical axis. The cross section of the light flux control patterns 638 may have various shapes such as a triangular groove, a square groove, an arc, an arch, and a parabola. In addition, the light flux control patterns 638 are not limited to being arranged concentrically, but may have various shapes such as circular dots, square dots, gratings, spots, spirals, and woven patterns.

The light guide member 630 may be made of PMMA (Poly Methyl Methacrylate) or PC (Poly Carbonate).

For example, the light guide member 630 may be made of PMMA (poly methyl methacrylate) or PC (haze) having a total light transmittance (Tt) of 90% or more as measured by the JIS K7361-1 measurement method and a haze of less than 0.5% Poly Carbonate).

In this embodiment, the light amount adjusting sheet 650 is formed on the first main surface 634 around the concave portion 636b and the concave portion 636b. The light amount adjusting sheet 650 may be adhered to the first main surface 634 or may be coated with a paint or a resin so as to be in close contact with the light guide member 630. The edge of the light amount adjusting sheet 650 may have a wavy or serrated pattern formed by a curved line or a straight line. The light amount adjusting sheet 650 may be a semi-transparent material through which only a part of light can be diffused, or may be a white transparent sheet.

In the above-described embodiments, the corners of the light guide member may have an oblique shape. For example, as shown in Figs. 8A and 8B, the edge of the light guide member 630 may have an oblique chamfer 634e. Further, edge grooves 634n may be formed at predetermined intervals from the ends of the light guide member. The rim groove 634n and the chamfered surface 634e serve to increase the amount of light emitted upward from the light source. That is, since the incident angle at the central portion of the light guide member close to the light source is small, the light amount passing through the first main surface 634 is diverged to the outside while the light reaching the far portion from the light source has a large incident angle, The amount of light emitted to the outside through the light guide plate 634 may be small. Therefore, the edge groove 634n may be formed on the first main surface 634 at a distance from the light source, or the chamfer surface 634e may be formed at the corner to increase the amount of light emitted to the outside.

9 is a view for explaining a light flux control member according to another embodiment of the present invention.

Referring to FIG. 9, as in FIG. 6, the light flux control member 700 according to the present invention may be disposed on only one of the plurality of light emitting devices. For example, four light flux controlling members 600 having a structure as shown in Figs. 89A and 8B may have a combined shape. However, the present invention is not limited to this, and the light flux controlling member 700 according to the present invention may be in the form of a combination of various numbers of structures shown in FIG. 1, such as two, three, six, eight, Or they may be arranged in the horizontal or vertical direction or linearly arranged.

Also, similarly to the above, the beam groove 734n may be formed at a position spaced a predetermined distance from the edge of the light flux controlling member 700, and a chamfer surface 734e may be formed at the corner.

10 is a view for explaining a light flux control member according to another embodiment of the present invention.

Referring to FIG. 10, the concave portion 836b of the light flux control member 800 according to the present invention may have a curved surface 834s whose center increases toward the light source from the edge toward the center.

The curved surface 834s has a large inclination near the reference light source and a gentle slope toward the periphery. Accordingly, the light in the vicinity of the reference optical axis having a large amount of light has a high total reflection probability because of the large angle of incidence on the normal of the curved surface 834s, and the incidence angle decreases toward the periphery, resulting in a low total reflection probability. Therefore, the amount of light in the vicinity of the reference optical axis can be dispersed to suppress white spots. In addition, the light amount control sheet 850 may be disposed on the curved surface 834s to uniformly disperse the light passing through the recess 834b to the surroundings. The light amount adjusting sheet 850 may be adhered to the first main surface 834 or may be coated with a paint or a resin to closely contact the light guide member 830.

Also in this embodiment, as described above, the beam groove 834n may be formed at a position spaced a predetermined distance from the edge of the light flux controlling member 800, and a chamfered surface 834e may be formed at the corner.

11 is a view for explaining a light flux control pattern according to another embodiment of the present invention.

Referring to FIG. 11, the luminous flux control pattern 738 according to the present invention may vary in size from the center to the edge. For example, the light flux control pattern 738 may have a constant width, an increase in height toward the edge, an increase in width with a constant height, an increase in height and width, an equal size, and a narrower or wider gap . This is not limited to the cross section of the light flux control pattern 738, but may be applied to various shapes such as circular arc, triangular wave pattern and the like.

In the drawings of the present invention, the light flux control members are shown to have the same length and width, but the light flux control member may have different widths and lengths. For example, when the screen magnification is 16: 9, the aspect ratio of the light flux control member may be 16: 9. However, the aspect ratio does not match the aspect ratio of the light flux control member, and the ratio may be freely selected.

100, 200: light flux control member 30: light guide member
50: light amount adjustment sheet 60: reflective coating layer

Claims (1)

A light guide member including a first main surface having a concave light incident surface on a reference optical axis of the light emitting device and a second main surface having a concave portion on the reference optical axis on a back surface of the first main surface; And
And a light amount adjusting sheet formed on at least the second main surface around the concave portion,
Wherein the concave portion includes both side walls and a horizontal plane between the side walls in a cross section passing the reference optical axis.

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