KR101503502B1 - Inclined type led package and back light unit comprising the same - Google Patents

Abstract

Here, a backlight unit capable of reducing the thickness of the light guide plate without significantly reducing the light efficiency is disclosed. The disclosed backlight unit includes a light guide plate on which light is incident through a side surface, the side surface being inclined to increase an incident light area of the light guide plate, and an LED package that emits light toward a side surface of the light guide plate. The LED package has a horizontal or vertical base surface and an elongated light exit surface existing on an oblique slope with respect to the base surface.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an inclined LED package and a backlight unit including the inclined LED package.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a slim type backlight unit and an inclined LED package that conforms to the slim type backlight unit.

Generally, a backlight unit is used for providing light to a display device. The backlight unit includes a light source and a light guide plate, and is disposed behind the display device. In addition, LEDs having a package structure, that is, LED packages, are widely used as light sources.

Conventionally, for example, a backlight unit in which an LED package and a light guide plate are disposed in close contact with each other is used in a mobile phone, a notebook computer, a navigation terminal, and the like. BACKGROUND ART [0002] In recent years, a backlight unit including an LED package has been applied to a TV including a high-definition display device. A side view LED package is mainly applied to a light source or a light emitting device of a backlight unit.

Figure 1 shows a conventional backlight unit. Referring to FIG. 1, a conventional backlight unit includes a light guide plate 2 and a side view LED package 4 disposed adjacent to a side surface 22 of the light guide plate 2. The side surface 22 of the light guide plate 2 on which light is incident is a vertical surface. The side view LED package 4 includes a reflector 42 having a cavity opened to the side and an LED chip 41 is mounted on the bottom surface of the cavity. For example, , The translucent member 44 covers the cavity and protects the LED chip 41. [ A fluorescent material for converting the wavelength of the light emitted from the LED chip 41 may be disposed inside the translucent member 44 or around the LED chip 41.

In recent years, the backlight unit has become slimmer, and accordingly, the thickness of the light guide plate 2 also tends to decrease. The reduction of the thickness of the light guide plate 2 reduces the area of the side surface 22 of the light guide plate 2, that is, the light incident surface. Accordingly, the thickness of the side view LED package 4 that emits light toward the light guide plate 2 must also be reduced. 2 is a view for explaining the influence of the thickness reduction of the conventional LED package 4 on the light efficiency. Referring to FIG. 2, as the thickness of the LED package 4 is reduced, the distance between the LED chip 41 and the wall of the reflector 42 (or the reflecting surface) is reduced, The amount of light is reduced. That is, the reduction in the thickness of the LED package causes a loss of light due to an increase in the amount of reflection of light.

Accordingly, there is a need in the art for a technique to realize a slim backlight unit by reducing the thickness of the light guide plate and the LED package without lowering the light efficiency.

SUMMARY OF THE INVENTION Accordingly, it is an aspect of the present invention to provide a backlight unit in which the light incidence area of the side surface is increased with respect to the light guide plate of a predetermined thickness to improve the light efficiency.

Another object of the present invention is to provide a light output surface on an inclined slope so that the emission surface area is increased without decreasing the overall height (or up, down, thickness) Type LED package.

A backlight unit according to an aspect of the present invention includes a light guide plate and an LED package. Light is incident on the light guide plate through its side face, and the side face is inclined to increase an incident area of the light. The LED package is arranged to emit light toward a side surface of the light guide plate.

Preferably, the LED package has a horizontal or vertical base surface and an elongated light exit surface existing on an oblique slope with respect to the base surface. At this time, it is more preferable that the light exit surface is rectangular. As used herein, the term " long " means " long relative to width ".

Preferably, the light exit surface is inclined at the same slope as the side surface of the light guide plate. In this specification, the term " same " includes the meaning of " almost (or substantially) identical ". The light exit surface may be a straight surface, a curved surface, or a surface of a different shape, and in this specification, the term 'slope' is a slope that can be measured at any position of the surface to represent the slope of that surface.

Preferably, the LED package includes an elongated cavity covered by the translucent member and defining the light exit surface, and an LED chip mounted on the bottom surface of the cavity. The bottom surface of the cavity is formed to be inclined so as to be parallel to the side surface of the light guide plate. At this time, the term " parallel " includes an approximate parallel.

Preferably, the cavities may be formed such that the cross-sectional reflective surfaces facing each other are opened at an angle of 90 degrees or more.

According to another aspect of the present invention, there is provided an inclined LED package that inclines light externally. The inclined LED package includes a horizontal or vertical base surface on which mounting is performed (with respect to the substrate) and an elongated light output surface existing on a slope forming an acute angle with the base surface. Note that the inclined LED package is best suited for emitting light toward the inclined side surface of the light guide plate in the above-described backlight unit, but may be applied to other applications.

Preferably, the inclined LED package includes an LED chip as a light source for making the light, a reflector having a cavity in which the LED chip is accommodated, and a translucent member covering the cavity and defining the light exit surface. An LED chip is mounted on a bottom surface of the cavity, and a bottom surface of the cavity is inclined, thereby enabling the LED chip to be inclined. The bottom surface of the cavity may have a lead terminal at a position where the LED chip is mounted. At this time, the cavities are formed in such a manner that reflecting surfaces on mutually facing cross sections are opened at an angle of 90 degrees or more. The bottom surface of the cavity, on which the LED chip is slantedly mounted, may be inclined at the same slope as the slope on which the light output surface is present.

According to the present invention, the side of the light guide plate on which the light is incident is formed into a sloped surface with a predetermined inclination, so that the light incidence area can be increased without reducing the thickness of the light guide plate, and the light efficiency of the backlight unit can be improved. The present invention also provides an inclined LED package including a horizontal or vertical base surface and an inclined surface that forms an acute angle with respect to the base surface, the inclined surface having an outgoing surface on the oblique surface, Thereby, the light emitting surface area of the LED package is increased without decreasing the overall height (or up, down, thickness) of the LED package. The structure of such an inclined LED package allows a larger reflection surface angle of the facing reflector when applied to an LED package with a reflector because the distance between the reflective surfaces of the conventional reflector and the LED chip is narrow Which contributes greatly to preventing light loss due to the reflection caused.

1 is a sectional view for explaining a conventional backlight unit;
2 is a view for explaining a decrease in light efficiency of a side view LED package according to a decrease in thickness of a conventional backlight unit.
3 is a view for explaining a backlight unit according to an embodiment of the present invention.
Figure 4 is a schematic perspective view of an inclined LED package that may be used in a backlight unit in accordance with an embodiment of the present invention.
5 is a cross-sectional view illustrating an inclined LED package according to an embodiment of the present invention.
6 is a view illustrating a backlight unit according to another embodiment of the present invention.
7 is a view illustrating an inclined LED package according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, and the like of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

3 and 4 are a cross-sectional view and a perspective view for conceptually explaining a backlight unit and an oblique LED package suitably used according to an embodiment of the present invention.

3, the backlight unit according to an embodiment of the present invention includes a light guide plate 100 and an inclined LED package 200 disposed adjacent to a side surface 102 of the light guide plate 100 do.

Light is incident on the light guide plate 100 through the side surface 102 and light guided into the inside of the light guide plate 100 is emitted to the outside through the top surface 104. As is well known, a large amount of total light is totally reflected in the light guide plate 100. A reflective pattern or a reflective film for reflecting the light upward may be formed on the bottom surface 103 of the light guide plate 100.

The side surface 102 of the light guide plate 100 is a surface to which light emitted from the LED package 200 is incident and is formed so as to be inclined to increase the incidence area of light. 3, the side surface 102 of the inclined light guide plate 100 has the same length as the thickness T of the light guide plate 100. However, in the present embodiment, The length L of one side of the light guide plate 120 is determined by the hypotenuse length of the right triangle including the side of the same length as the light guide plate thickness T and the side intersecting at right angles with the light guide plate 120, Therefore, the side surface area of the light guide plate 102, that is, the incident area of the light can be greatly increased without increasing the thickness of the light guide plate 100. [

 The inclined LED package 200 is disposed adjacent to the inclined side surface 102 of the light guide plate 100 and emits light toward the inclined side surface 102. 3 and 4, the LED package 200 includes a horizontal base surface 202 on which a substrate (not shown) is mounted, a slope surface Elongated light exit surface 204 existing on the outer surface of the light guide plate 201. [

The light emitting surface 204 of the LED package 200 is long enough to supply light to the side surface 102 of the light guide plate 100 in a long length range. At this time, the slope of the light exit surface 204 is preferably the same as the slope of the side surface 102 of the light guide plate 100. An LED chip 210 for generating light is shown as a silver line inside the LED package 200, that is, below the light exit surface 204.

In this embodiment, the side surface 102 of the light guide plate 100 is an inclined surface whose upper edge extends further outward than the lower edge. Correspondingly, the inclined LED package 200 is disposed such that its inclined light output surface 204 faces the inclined side surface 102 of the light guide plate 10 from below to above.

In this specification, the term 'base surface' means, for example, a surface on which the LED package 200 is mounted while facing a substrate such as a PCB. Accordingly, if the vertical plane 203 perpendicular to the horizontal plane 202 of the LED package is mounted to face the substrate, the vertical plane 203 may be the base plane.

5 is a cross-sectional view illustrating the inclined LED package in more detail according to an embodiment of the present invention.

5, the inclined LED package 200 of the present embodiment includes a horizontal base surface 202 and a light exit surface 204 on an oblique angle with respect to the base surface 202, as described above, . The LED package 200 includes an LED chip 210 and a reflector 220. The reflector 220 includes a cavity in which the LED chip 210 is accommodated. The cavity includes a bottom surface 221 on which the LED chip 210 is mounted, first and second 2 reflecting surfaces 222a and 222b. The bottom surface 221 and the first and second reflective surfaces 222a and 222b may be continuous in the longitudinal direction of the LED package because the light emitting surface 204 and the cavity are elongated rectangular shapes 4).

In order to supply power to the LED chip 210, the reflector 220 is provided with first and second lead terminals 232a and 232b. The first and second lead terminals 232a and 232b extend from the inner bottom surface 221 of the cavity to the horizontal base surface 202 defined at the outer lower portion of the reflector 220 respectively. The lead terminals are electrically connected to the LED chip 210 by bonding wires.

When the inclined LED package 200 is applied to the backlight unit described above, the light exit surface 204 and the bottom surface 221 of the cavity are located on the side 102 (see FIG. 3) of the light guide plate, that is, It is preferable that it is determined to be the same as the slope of the incident surface. The LED chip 210 is obliquely mounted on the inclined cavity bottom surface 221. 3) of the light guide plate 100 (see FIG. 3), the optical axis of the LED chip 210 is inclined to the inclined side surface of the light guide plate 100 As shown in FIG. The cavity is covered with a translucent member 240 capable of transmitting light, whereby the LED chip 210 can be protected. In this embodiment, the upper surface of the translucent member 240 defines the light exit surface 204 of the above-described LED package.

The translucent member 240 may be a resin encapsulant such as epoxy or silicone which fills the cavity as a whole. Also, the translucent member 240 may be a resin, glass, quartz, or a transparent ceramic material covering only the upper portion of the cavity. In this embodiment, the upper surface of the translucent member 240 is planar, but may be any pattern surface such as a curved surface or a Fresnel pattern, for adjusting the directing angle of light.

On the other hand, the angle between the first reflection surface 222a and the second reflection surface 222b of the reflector is preferably as large as possible so as to minimize light loss due to reflection. In this embodiment, the angle A between the first reflection surface 222a and the second reflection surface 222b is 90 degrees, but it may exceed 90 degrees. The first reflection surface 222a and the second reflection surface 222b are preferably planar or substantially flat surfaces.

It is most preferable that the inclined LED package 200 described above is used in the backlight unit together with the inclined side face light guide plate 100. However, it should be noted that the inclined LED package 200 can be applied to other uses such as a lighting apparatus, in addition to the light source of the backlight unit.

FIG. 6 is a cross-sectional view illustrating a backlight unit according to another exemplary embodiment of the present invention. Referring to FIG. 6, the light guide plate 100 includes a slanted side 102 on which light is incident, Unlike the previous embodiment, the lower edge is an inclined surface that extends further outward than the upper edge. Corresponding to this, the inclined LED package 200 is arranged such that its inclined light output surface 204 looks downward from the inclined side surface 102 of the light guide plate 100. Since the bottom surface of the light guide plate 200 has a structure of a reflective film or a reflective pattern, even if a large amount of light is directly directed to the bottom surface of the light guide plate 100, the light can be reflected upward.

7 is a cross-sectional view illustrating an inclined LED package according to another embodiment of the present invention. 7, the inclined LED package 200 of the present embodiment is similar to the inclined LED package 200 of the present embodiment in that the LED package of the previous embodiment has a generally right triangular cross-section, whereas the inclined LED package 200 of this embodiment has a generally obtuse- Section. Furthermore, the LED package 200 has an obtuse angle at which the angle B formed by the two reflective surfaces 222a and 222b on the transverse section is greater than 90 degrees.

Claims (11)

As a backlight unit,
The light incident on the side surface, the side surface being inclined to increase the incidence area of the light;
And an LED package that emits light toward a side surface of the light guide plate,
Wherein the LED package has an elongated cavity having a horizontal or vertical base surface and an elongated light exit surface existing at an acute angle with respect to the base surface, the long cavity being covered by the translucent member to define the light exit surface, And an LED chip mounted on a bottom surface of the cavity, wherein the bottom surface of the cavity is inclined so as to be parallel to the side surface of the light guide plate,
Wherein the cavity is formed such that the angle formed by the reflective surfaces on the cross section facing each other is greater than 90 degrees. delete The backlight unit according to claim 1, wherein the LED package has a horizontal or vertical base surface and a rectangular light exit surface existing on an oblique slope with respect to the base surface. The backlight unit according to claim 1 or 3, wherein the light exit surface is inclined at the same slope as the side surface of the light guide plate. delete delete An inclined LED package for emitting light obliquely to the outside,
A horizontal or vertical base surface on which mounting is performed,
And an elongated light exit surface present on a slope forming an acute angle with said base surface,
A reflector formed with a cavity in which the LED chip is accommodated, and a translucent member covering the cavity to define the light exit surface, wherein the LED chip is mounted on a bottom surface of the cavity, The bottom surface of the cavity is formed obliquely,
Wherein the cavity is formed such that the angle formed by the reflective surfaces on the cross section facing each other is greater than 90 degrees. The inclined LED package according to claim 7, wherein the light exit surface is rectangular. delete delete 9. The inclined LED package according to claim 8, wherein the bottom surface of the cavity, on which the LED chip is slantedly mounted, is inclined at the same slope as the slope on which the light exit surface exists.

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