KR101106176B1 - Inclined type led package and back light unit comprising the same - Google Patents

Abstract

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

Back light unit, Light guide plate, Base surface, Inclined, LED package, Acute angle, Light exit surface

Description

Inclined LED package and backlight unit including the same {INCLINED TYPE LED PACKAGE AND BACK LIGHT UNIT COMPRISING THE SAME}

TECHNICAL FIELD The present invention relates to a backlight unit, and more particularly, to a slim backlight unit and an inclined LED package well suited thereto.

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

Conventionally, for example, a backlight unit in which an LED package and a light guide plate are closely attached to a mobile phone, a notebook computer, a navigation terminal, or the like is used. In recent years, a backlight unit including an LED package is applied to a TV including a high quality display device. Side view LED package is mainly applied as a light source or a light emitting device of the backlight unit.

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 plane. In addition, the side view LED package 4 includes a reflector 42 having a cavity open to the side, the LED chip 41 is mounted on the bottom surface of the cavity, for example, a resin encapsulant Transmitting member 44, such as, covers the cavity to protect the LED chip 41. In addition, there may be a phosphor inside the light transmitting member 44 or around the LED chip 41 to convert the wavelength of the light emitted from the LED chip 41.

In recent years, the backlight unit tends to become slim, and thus, the thickness of the light guide plate 2 also tends to decrease. Reducing 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 emitting light toward the light guide plate 2 should also be reduced. 2 is a view for explaining the effect 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 decreases, the distance between the LED chip 41 and the wall (or reflecting surface) of the reflector 42 decreases, thereby leaving the wall outside without hitting the wall. It can be seen that the amount of light is reduced. That is, the reduction in the thickness of the LED package causes a loss of light due to the increased amount of reflection of light.

Accordingly, there is a need in the art for a technology for implementing a slimmer backlight unit by reducing the thickness of the light guide plate and the LED package without reducing the light efficiency.

Accordingly, one technical problem of the present invention is to provide a backlight unit having improved light efficiency by increasing the light incident area on the side surface of a light guide plate having a predetermined thickness.

Another technical problem of the present invention is to provide a light exit surface on an inclined slope, so that the area of the exit surface is increased without reducing the overall height (or up, down, thickness), and thus can be suitably used for the backlight unit. Is to provide LED package.

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According to one aspect of the invention, a backlight unit is provided. The backlight unit may include a light guide plate in which light is incident through a side surface, and the side surface is inclined to increase an incident area of the light; It is mounted on a substrate, and includes an LED package for emitting light toward the side of the light guide plate. The LED package includes a horizontal base surface mounted to the substrate and an elongated light exit surface present on an inclined surface at an acute angle with respect to the base surface, wherein the LED package includes an LED chip. Including a cavity including a bottom surface and a first reflecting surface and a second reflecting surface to be mounted therein, the light exit surface is limited to the light transmitting member covering the cavity, the bottom surface corresponds to the light exit surface The first lead terminal and the second lead terminal for supplying power to the LED chip extend from the bottom surface to the base surface, and each of the first lead terminal and the second lead terminal is the bottom; And a portion inclined to correspond to the surface, and a portion horizontally corresponding to the base surface.
In the present specification, the term 'wait' means 'longer length than 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 'identical' includes the meaning of 'almost (or approximately) identical'. The light exit surface may be a straight surface, a curved surface, or a surface of another shape, and in this specification, the term 'tilt' is sufficient if it is a slope that can be measured at any position of the surface to represent the slope of the surface.

Preferably, the LED package includes an elongated cavity which is covered by the light transmitting member to define 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 parallel to the side of the light guide plate. In this case, the term 'parallel' includes roughly parallel.

Preferably, the cavity may be formed by spreading the reflective surfaces on the cross sections facing each other at an angle of 90 degrees or more.

According to another aspect of the invention, there is provided an inclined LED package that emits light obliquely to the outside. The inclined LED package includes a horizontal or vertical base surface on which the mounting is performed (relative to the substrate), and an elongate light exit surface existing on a slope formed at an acute angle with the base surface. Note that the inclined LED package is best suited for emitting light toward the inclined side 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 generating the light, a reflector having a cavity in which the LED chip is accommodated, and a light transmitting member covering the cavity to define the light exit surface. The LED chip is mounted on the bottom surface of the cavity, and the bottom surface of the cavity is inclined, thereby enabling the LED chip to be inclined. The bottom surface of the cavity may include a lead terminal at a position where the LED chip is mounted. In this case, the cavity is formed by the reflective surfaces on the cross section facing each other spread over 90 degrees. The bottom surface of the cavity in which the LED chip is mounted obliquely may be inclined at the same slope as the slope where the light exit surface exists.

According to the present invention, the light guide plate side to which light is incident may be formed as an inclined surface having a predetermined inclination, thereby increasing the light incident area without reducing the thickness of the light guide plate, thereby improving the light efficiency of the backlight unit. The present invention also provides an inclined LED package including a horizontal or vertical base surface and an inclined slope formed at an acute angle with respect to the base surface, and provided with an emission surface of light on the slope, Thereby, the light exit area of the LED package is increased without reducing the overall height (or up, down, thickness) of the LED package. Such an inclined LED package structure, when applied to an LED package with a reflector, can widen the angle of the reflecting surface of the reflecting reflector, resulting in a narrow gap between the reflecting surfaces of the conventional reflector and the LED chip. It contributes greatly to preventing light loss due to reflections caused.

Hereinafter, exemplary 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. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

3 and 4 are cross-sectional views and perspective views for conceptually explaining a backlight unit and an inclined LED package suitable for use in accordance with an embodiment of the present invention.

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

In the light guide plate 100, light is incident through the side surface 102, and light entering and guided inside is emitted to the outside through the upper surface 104. As is well known, a large amount of total internal reflection occurs in the light guide plate 100. The bottom surface 103 of the light guide plate 100 may be formed with a reflective pattern or a reflective film for reflecting the light upward.

The side surface 102 of the light guide plate 100 is a surface on which light emitted from the LED package 200 is incident, and is formed to be inclined to increase an incident area of the light. Conventionally, the length of one side of the side on which light is incident is equal to the thickness T of the light guide plate 100, whereas as shown in FIG. 3, in the present embodiment, the side surface 102 of the inclined light guide plate 100 is used. The length L of one side is determined by the hypotenuse length of a right triangle including a side having a length equal to the thickness of the light guide plate T and a side crossing at right angles thereof, and larger than the thickness of the light guide plate 120. Therefore, the side surface area of the light guide plate 102, that is, the incident area of light, can be greatly increased without increasing the thickness of the light guide plate 100.

 The inclined LED package 200 emits light toward the inclined side surface 102 while being disposed adjacent to the inclined side surface 102 of the light guide plate 100. 3 and 4, the LED package 200 includes a horizontal base surface 202 mounted to a substrate (not shown), and a sloped at an acute angle with respect to the base surface 202. A rectangular elongated light exit surface 204 existing in the surface is provided outside.

The LED package 200 has a long light emitting surface 204 is formed, it can supply light in a long length range with respect to the side surface 102 of the light guide plate (100). In this case, the inclination of the light exit surface 204 is preferably the same as the inclination of the side surface 102 of the light guide plate 100. Inside the LED package 200, that is, below the light exit surface 204, an LED chip 210 for generating light is illustrated by a hidden line.

In the present 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 arranged such that its inclined light exit surface 204 faces the inclined side surface 102 of the light guide plate 10 from below.

In the present 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. Therefore, if the vertical surface 203 perpendicular to the horizontal surface 202 of the LED package is mounted to face the substrate, the vertical surface 203 may be the base surface.

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

Referring to FIG. 5, the inclined LED package 200 according to the present embodiment includes, as mentioned above, a horizontal base surface 202 and a light exit surface 204 on a slope formed at an acute angle therewith. Doing. In addition, 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, and the cavity includes a bottom surface 221 on which the LED chip 210 is mounted, and first and second cross sections facing each other. 2 reflective surfaces 222a and 222b. Since the LED package has a long rectangular light exit surface 204 and a cavity, the bottom surface 221 and the first and second reflective surfaces 222a and 222b may be continuous in the length direction of the LED package ( See FIG. 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. In the present embodiment, the first and second lead terminals 232a and 232b respectively extend from the inner bottom surface 221 of the cavity to the horizontal base surface 202 defined at the outer bottom of the reflector 220. 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 have a side surface 102 (see FIG. 3) of the light guide plate, that is, light It is preferable to be determined in the same manner as the inclination of the incident surface. The LED chip 210 is mounted to be inclined on the inclined cavity bottom surface 221. As a result, the optical axis of the LED chip 210 is inclined, and when light is sent to the inclined side surface 102 (see FIG. 3) of the light guide plate 100 (see FIG. 3), the optical axis is the inclined side surface of the light guide plate. Can intersect perpendicularly to. The cavity is covered by a light transmitting member 240 that can transmit light, whereby the LED chip 210 can be protected. In this embodiment, the upper surface of the light transmitting member 240 defines the light exit surface 204 of the LED package described above.

The light transmitting member 240 may be an encapsulant made of a resin material, such as epoxy or silicone, which fills the entire cavity. In addition, the light transmitting member 240 may be a lens made of resin, glass, quartz, or a transparent ceramic material covering only the upper portion of the cavity. In the present exemplary embodiment, the top surface of the light transmitting member 240 is a flat surface, but may be any pattern surface such as a curved surface or a Fresnel pattern to adjust the direction of light.

On the other hand, the angle between the first reflecting surface 222a and the second reflecting surface 222b of the reflector is preferably as large as possible to minimize the light loss due to reflection. In the present embodiment, the angle A between the first reflective surface 222a and the second reflective surface 222b is 90 degrees, but may be greater than 90 degrees. In addition, the first reflective surface 222a and the second reflective surface 222b may be flat or substantially flat surfaces.

The above-described inclined LED package 200 is most preferably used in the backlight unit together with the light guide plate 100 inclined side. However, it should be noted that the inclined LED package 200 may be applied to other applications such as a luminaire as well as a light source of the backlight unit.

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 an inclined side surface 102 to which light is incident, and the side surface 102 includes: Unlike the previous embodiment, the lower edge is an inclined surface extending outward than the upper edge. Correspondingly, the inclined LED package 200 is disposed such that its inclined light exit surface 204 looks down the inclined side surface 102 of the light guide plate 100 from above. Since the bottom 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 directed directly to the bottom of the light guide plate 100, the light may be reflected upward.

7 is a cross-sectional view showing a sloped LED package according to another embodiment of the present invention. Referring to FIG. 7, the inclined LED package 200 of the present embodiment has an overall rectangular cross section while the LED package of the previous embodiment has a generally triangular cross section. Have a cross section; Furthermore, the LED package 200 has an obtuse angle of more than 90 degrees between the angles B formed by the two reflective surfaces 222a and 222b on the cross section.

1 is a cross-sectional view illustrating a conventional backlight unit.

2 is a view for explaining the light efficiency degradation of the side view LED package according to the thickness reduction of the conventional backlight unit.

3 is a view for explaining a backlight unit according to an embodiment of the present invention.

4 is a schematic perspective view of an inclined LED package that may be used in a backlight unit in accordance with one embodiment of the present invention.

5 is a cross-sectional view illustrating a sloped LED package according to an embodiment of the present invention.

6 illustrates a backlight unit according to another embodiment of the present invention.

7 is a view showing a sloped LED package according to another embodiment of the present invention.

Claims (11)

As a backlight unit, Light is incident through the side, the side is a light guide plate inclined so as to increase the incident area of the light; A LED package mounted on a substrate, the LED package emitting light toward a side of the light guide plate; The LED package has a horizontal base surface mounted on the substrate and an elongated light exit surface existing on a slope formed at an acute angle with respect to the base surface. The LED package includes a cavity including a bottom surface on which an LED chip is mounted and a first reflection surface and a second reflection surface therein, and the light emission surface is limited to a light transmitting member covering the cavity. The bottom surface is inclined to correspond to the light exit surface, A first lead terminal and a second lead terminal for supplying power to the LED chip extend from the bottom surface to the base surface, And each of the first lead terminal and the second lead terminal includes a portion inclined to correspond to the bottom surface and a portion horizontally corresponding to the base surface. delete The backlight unit of claim 1, wherein the light exit surface has a rectangular shape. The backlight unit of claim 1 or 3, wherein the light exit surface is inclined at the same slope as a side surface of the light guide plate. delete delete An inclined LED package mounted on a substrate and emitting light obliquely to the outside, A horizontal base surface on which the substrate is mounted; An external light exiting surface present on a slope formed at an acute angle with the base surface; The light emitting surface is limited to a light transmitting member covering the cavity, including a cavity including a bottom surface on which an LED chip is mounted and a first reflection surface and a second reflection surface. The bottom surface is inclined to correspond to the light exit surface, A first lead terminal and a second lead terminal for supplying power to the LED chip extend from the bottom surface to the base surface, Each of the first lead terminal and the second lead terminal may include an inclined portion corresponding to the bottom surface and a horizontal portion corresponding to the base surface. The inclined LED package according to claim 7, wherein the light exit surface is rectangular. delete delete delete

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