KR20170084483A - Lens, a light emitting device and a display apparstus including the same - Google Patents

Abstract

The present invention provides a light emitting device comprising a substrate, a light emitting element disposed on the substrate and emitting light, and a lens formed in surface contact with at least one surface of the light emitting element, And a curved surface for converging the light toward the region.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lens, a light emitting device package including the same,

Embodiments relate to a lens, a light emitting device package including the same, and a display device.

GaN, and AlGaN are widely used for optoelectronics and electronic devices due to their advantages such as wide and easy bandgap energy.

Particularly, a light emitting device such as a light emitting diode or a laser diode using a semiconductor material of a 3-5 group or a 2-6 group compound semiconductor has been widely used in various fields such as red, green, blue and ultraviolet rays It can realize various colors, and it can realize efficient white light by using fluorescent material or color combination. It has low power consumption, semi-permanent lifetime, fast response speed, safety, and environment compared to conventional light sources such as fluorescent lamps and incandescent lamps Affinity.

Therefore, a transmission module of the optical communication means, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, a white light emitting element capable of replacing a fluorescent lamp or an incandescent lamp Diode lighting, automotive headlights, and traffic lights.

The LCD display device includes a liquid crystal layer and a TFT substrate and a color filter substrate facing each other with the liquid crystal layer interposed therebetween, and can display an image using light provided from the display device because there is no self-luminous force.

Currently, light emitting device packages mainly used for display devices, outdoor billboards, etc. are basically consumed for reasons of low power consumption and environment friendly.

In recent years, a need for a light emitting device package that emits light in the ultraviolet (UV) region is increasing.

The light emitting device package that emits light in the ultraviolet ray region has advantages that it can be utilized as water purification, sterilization, and the like.

However, the conventional display device and the lens used in the light emitting device package used for the illumination have been developed and developed for the purpose of radiating light in a wide area by enlarging the light emitting area. However, the light emitting device package emitting light in the ultraviolet region has a wide There is a need for a lens that narrows the directivity distribution and a light emitting device package and a display device including the same that emit focused light more than light is irradiated to the region.

SUMMARY OF THE INVENTION The present invention is directed to a lens for narrowing the directivity distribution of a light emitting device package and condensing light in an ultraviolet region band emitted from the light emitting device package, and a light emitting device package and a display device including the same.

According to an aspect of the present invention, there is provided a light emitting device including a substrate, a light emitting element disposed on the substrate and emitting light, and a lens formed to be in surface contact with at least one surface of the light emitting element, And a curved surface for condensing light emitted from the light emitting element toward a predetermined region.

In addition, the curved surface is a concave surface concave toward the light emitting element.

Further, the radius of curvature of the concave surface is determined by the position of the light emitting element and the predetermined region or the refractive index of the lens.

It is a further object of the present invention to provide a light emitting device package in which the concave surface has a curvature radius determined by the following equation.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens.

In addition, the refractive index of the lens is 1.41 to 1.53.

The lens housing includes a lens housing defining an outer appearance and a concave surface concave toward at least one lower portion of the lens housing. The concave surface is configured such that light emitted from the light emitting device disposed on the lower surface of the lens housing is condensed in a predetermined area It is a solution to the problem to provide a lens having a radius of curvature.

Further, the concave surface of the lens is provided with a lens which is determined by the following formula.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens.

Further, the lens has a refractive index of 1.41 to 1.53.

In addition, the present invention also includes a bottom chassis, an optical sheet driving substrate disposed to face the bottom chassis, at least one light emitting device disposed on the driving substrate, and a plurality of optical members for controlling light emitted from the at least one light emitting device And the optical member includes a lens including at least one concave surface for condensing the light emitted from the light emitting device into a predetermined area.

Further, the concave surface of the lens is determined by the following expression.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens.

The present invention can focus the light of the ultraviolet region band emitted from the light emitting device package through the structural design of the lens that narrows the directivity distribution of the light emitting device package.

In addition, since the light emitted from the light emitting device package is condensed, the sterilization performance can be maximized while minimizing the light loss.

In addition, since the light emitted from the light emitting device package is condensed, the number of the light emitting device packages can be reduced.

1 is a side sectional view showing a conventional light emitting device package including a lens.
2 is a side sectional view showing a conventional light emitting device package including a molding part.
3A and 3B illustrate an embodiment of a light emitting device package.
FIG. 4 is a view showing a coupling relationship between the light emitting device package and the lens. FIG.
5 and 6 show a display device including a light emitting device package.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

In the description of the embodiment according to the present invention, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

FIG. 1 is a side sectional view showing a conventional light emitting device package 10A including a lens, and FIG. 2 is a side sectional view showing a conventional light emitting device package 10B including a molding part.

In the light emitting device package 10A of FIG. 1, the light emitting element 12 is disposed on the substrate 16, and the lead frames 14 and 15 are formed on the substrate 16.

Electrodes (not shown) of the light emitting element 12 are connected to the lead frames 14 and 15 by wire bonding. A lens 11 may be provided on the light emitting element 12.

The light emitting device package 10B of Fig. 2 may include a substrate 16 and a light emitting element 12 disposed on the substrate 16. [

2 shows a molding unit 17 formed in the center hole of the body 18 for protecting the light emitting device 12 and includes a body 18 formed to surround the light emitting device 12 on the substrate 16, . ≪ / RTI >

A diffusion agent may be contained in the molding part 17.

In addition, a fluorescent material may be further included in the molding part 17.

However, since the light emitted from the light emitting device 12 is radiated to the outside of the light emitting device packages 10A and 10B along a certain optical path, the light emitting device packages 10A and 10B disclosed in FIGS. 1 and 2, And the function for changing or adjusting the irradiation beam angle is not provided in the light emitting element 12, so that the light distribution angle is narrow and can not be changed.

In order to solve this problem, a lens, a light emitting device package, and a display device including the same according to the present invention will be described with reference to FIGS.

3A and 3B illustrate an embodiment of a light emitting device package.

Referring to FIG. 3A, the first lead frame 210 and the second lead frame 210 are electrically separated by an insulating member 220, and the side walls 230 constitute a package body. The first lead frame and the second lead frame 210 constitute the bottom surface of the cavity, and the molding part 270 can be filled in the cavity.

3A, a flip-chip type light emitting device in which wires are omitted may be disposed in the light emitting device package 200, so that the light extraction efficiency may be better. Therefore, it is possible to make the area where the light exits from the surface of the light emitting device package to be smaller, and the width (b) at the entrance of the cavity, which is a region where light is emitted as shown in the figure, can be, for example, 15 mm to 18 mm have. The width at the entrance of the cavity is not limited thereto and may have a different value depending on the size of the light emitting device package or the lens.

FIG. 3B shows the light emitting device of FIG. 3A.

Referring to FIG. 3B, the light emitting device 250 includes a substrate 251, a buffer layer 252 disposed on the substrate 251, a first conductive semiconductor layer 253a, an active layer 253b, The light emitting structure 253 including the first conductivity type semiconductor layer 253a and the second conductivity type semiconductor layer 253c on the light emitting structure 253 and the light transmitting structure 253 on the light emitting structure 253, And a first electrode 257 and a second electrode 258, respectively. The buffer layer 252 may be disposed between the substrate 251 and the light emitting structure 253, but is not limited thereto.

The substrate 251 may be formed of a material suitable for semiconductor material growth or a carrier wafer, may be formed of a material having excellent thermal conductivity, and may include a conductive substrate or an insulating substrate. For example, at least one of sapphire (Al ₂ O ₃ ), SiO ₂ , SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge and Ga ₂ O ₃ can be used.

When the substrate 251 is formed of sapphire or the like and the light emitting structure 253 including GaN or AlGaN is disposed on the substrate 251, lattice mismatch between GaN and AlGaN and sapphire is very large Since the difference in thermal expansion coefficient between them is also very large, dislocations, melt-backs, cracks, pits, and surface morphology defects that deteriorate the crystallinity may occur The buffer layer 252 can be formed of AlN or the like.

The first conductive semiconductor layer 253a may be disposed on the substrate 251 and may be formed of a compound semiconductor such as a group III-V or II-VI group. The first conductive semiconductor layer 253a may be doped with a first conductive dopant, Semiconductor layer. The first conductivity type semiconductor layer 253a may be formed of a compositional formula of Al _x In _y Ga _(1-xy) N (0? _{X ? 1, 0? Y ? 1} , 0? X + y? And may be formed of any one or more of AlGaN, GaN, InAlGaN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

When the first conductivity type semiconductor layer 253a is an n-type semiconductor layer, the first conductivity type dopant may include n-type dopants such as Si, Ge, Sn, Se, and Te. The first conductive semiconductor layer 253a may be formed as a single layer or a multilayer, but is not limited thereto.

The active layer 253b may be disposed on the upper surface of the first conductivity type semiconductor layer 253a and may have a structure such as a double well structure, a multi-well structure, a single quantum well structure, a multi quantum well (MQW) ) Structure, a quantum dot structure, or a quantum wire structure.

InGaN / InGaN, InGaN / InGaN, InGaN / GaN, InAlGaN / GaN, GaAs (InGaAs), and the active layer 253b may be formed using a compound semiconductor material of Group III- / AlGaAs, GaP (InGaP) / AlGaP, but is not limited thereto. The well layer may be formed of a material having an energy band gap smaller than the energy band gap of the barrier layer.

The second conductivity type semiconductor layer 253c may be formed of a semiconductor compound on the active layer 253b. The second conductive semiconductor layer 253c may be formed of a compound semiconductor such as a group III-V or a group II-VI, and may be doped with a second conductive dopant. The second conductivity type semiconductor layer 253c is formed of a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0 = x = 1, 0 = y = 1, 0 = x + y = 1) The second conductivity type semiconductor layer 253c may be formed of any one or more of AlGaN, GaN AlInN, AlGaAs, GaP, GaAs, GaAsP and AlGaInP. When the second conductivity type semiconductor layer 253c is a p-type semiconductor layer, the second conductivity type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The second conductivity type semiconductor layer 253c may be formed as a single layer or a multilayer, but is not limited thereto.

In this embodiment, the first conductivity type semiconductor layer 253a may be an n-type semiconductor layer, and the second conductivity type semiconductor layer 253c may be a p-type semiconductor layer. However, The second conductivity type semiconductor layer 253c may be a p-type semiconductor layer, the second conductivity type semiconductor layer 253c may be an n-type semiconductor layer, and the second conductivity type semiconductor layer 253c may have a polarity opposite to that of the second conductivity type. 3 conductivity type semiconductor layer can be formed. Accordingly, the light emitting structure can be realized by a structure such as an n-p junction structure, a p-n junction structure, an n-p-n junction structure, or a p-n-p junction structure.

Although not shown, an electron blocking layer may be disposed between the active layer 253b and the second conductive semiconductor layer 253c. The electron blocking layer may have a superlattice structure. For example, the superlattice may include AlGaN doped with a second conductive dopant, and GaN having a different composition ratio of aluminum may be formed as a layer And a plurality of these may be alternately arranged.

A part of the active layer 253b and the first conductivity type semiconductor layer 253a are mesa-etched from the second conductivity type semiconductor layer 253 in a part of the light emitting structure 253 to form a part of the first conductivity type semiconductor layer 253a The surface may be exposed.

The first electrode 257 and the second electrode 258 are disposed on the exposed surface of the first conductive type semiconductor layer 253a and the second conductive type semiconductor layer 253c, The two electrodes 258 may be formed as a single layer or a multilayer structure including at least one of aluminum (Al), titanium (Ti), chrome (Cr), nickel (Ni), copper (Cu) , Respectively, to a wire (not shown).

The first electrode pad 261 and the second electrode pad 262 are disposed on the submount 260 and the first electrode pad 261 and the second electrode pad 262 are electrically connected to the bumps 267 and 268 And may be bonded to the first electrode 257 and the second electrode 258, respectively.

4 is a view showing a coupling relationship between the light emitting device package and the lens.

4, the light emitting device package of the embodiment includes a light emitting device 200 and a lens 100, which is formed to surround at least one surface of the light emitting device 200 and changes a path of light emitted from the light emitting device 200, . ≪ / RTI >

The lens 100 may further include a lens housing 101 that forms an appearance.

As described above, the conventional display device and the lens 100 used in the light emitting device package used for the illumination have been applied and developed for the purpose of radiating light in a wide area by enlarging the light emitting area. However, A light emitting device package and a display device including the lens and the light emitting device package including the same that narrows the directivity distribution is more important than the light emitting device package that emits the condensed light rather than the light emitting device.

More specifically, a light emitting device package including the light emitting device 200 or at least one light emitting device 200 may have a predetermined directional angle distribution.

The light emitting device 200 that emits light having a wavelength band of ultraviolet rays can be used for medical equipment or the like. In this case, a user needs a light emitting device package capable of irradiating light only to a necessary portion.

The lens 100 of the embodiment may be configured such that light emitted from a light emitting device package including a plurality of light emitting devices 200 is converged to a predetermined use region.

The lens 100 may be made of silicon (Silocon) and may have a concave shape facing the light emitting device 200 on one side.

The radius of curvature r of the concave surface provided in the concave shape of the light emitting device 200 can be determined by the following equation.

a means that the lens 100 is a light which reaches the concave surface of the lens 100 from the top surface of the light emitting device 200 at the trace of the shortest distance at which the light emitted from the center of the light emitting device 200 reaches the use area, B is the length of the optical path from the concave surface of the lens 100 to the use area, n 'is the refractive index in the air, and n is the refractive index inside the lens 100.

When the lens 100 is made of silicon, the refractive index n of the inside of the lens 100 may be 1.41 to 1.53.

The light emitting device package may include a plurality of light emitting devices 200 arranged linearly.

In addition, the light emitting device package may include a plurality of light emitting devices 200 arranged in a matrix form.

For example, if the light emitting device package includes sixteen light emitting devices 200, all of the sixteen light emitting devices 200 may be arranged in a row, and sixteen light emitting devices 200 may be arranged in a matrix of 4X4 It is possible.

However, the embodiment described above is for the purpose of describing an example, and the user can further modify the shape of the light emitting device 200 disposed in the light emitting device package according to need, Or more.

Regardless of the arrangement of the light emitting device 200, the light emitting device package of the embodiment may be provided such that light emitted from the plurality of light emitting devices 200 is converged toward a predetermined use area.

This is because the radius of curvature r that determines the shape of the lens 100 is smaller than the distance from the upper surface of the light emitting element 200 at the shortest distance where the light emitted from the center of the light emitting element 200 reaches the use area. ), Which is the length of the optical path reaching the concave surface of the lens 100, and b, which is the length of the optical path reaching the use area outside the lens 100.

5 and 6 show a display device including a light emitting device package.

5 and 6, a display device 400 according to an embodiment of the present invention includes a bottom chassis 435, an optical sheet 420 disposed to face the bottom chassis 435, And a light emitting device package disposed on the optical sheet 420 and spaced apart from the optical sheet 420.

5, a driving unit cover 440 that surrounds the driving unit 455 and the driving unit 455 may be disposed on the bottom chassis 435 of the display device 400.

The front cover 430 may include a transparent front panel (not shown) that transmits light. The front panel protects the liquid crystal panel 430a at a predetermined interval, and the light emitted from the optical sheet 420 The image displayed on the liquid crystal panel 430a can be viewed from the outside.

The bottom cover 435 may be combined with the front cover 430 to protect the optical sheet 420 and the liquid crystal panel 430a.

A driving unit 455 may be disposed on one surface of the bottom cover 435.

The driving unit 455 may include a driving control unit 455a, a main board 455b, and a power supply unit 455c. The drive controller 455a may be a timing controller and is a driver for adjusting the operation timing of each driver IC of the liquid crystal panel 430a. The main board 455b may include a V-sync, an H- B resolution signal, and the power supply unit 455c is a driving unit for applying power to the liquid crystal panel 430a.

The driving unit 455 may be provided on the bottom cover 435 and may be surrounded by the driving unit cover 440.

The bottom cover 435 may include a plurality of holes to connect the liquid crystal panel 430a and the driving unit 455 and a stand 460 for supporting the display device 400. [

6, the reflective sheet 435a is disposed on the surface of the bottom cover 435, the light emitting device package 200 is disposed on the reflective sheet 435a, and the lens 100 is mounted on the front surface of the light emitting device package 200. [ .

The light emitted from the light emitting device package 200 and emitted from the lens 100 may be transmitted to the optical sheets 421 to 423 through the light transmission area 435b have.

The light having passed through the optical sheets 421 to 423 can be directed to the liquid crystal panel 430a.

6, the distance d ₁ between the reflective sheet 435a and the optical sheet 421 may be 10 to 15 millimeters, and the height d ₂ of the light emitting device package 200 including the lens 100 may be 7 mm, and may be smaller than the distance d ₁ between the reflective sheet 435a and the optical sheet 421.

Even if the distance d ₁ between the reflective sheet 435a and the optical sheet 421 is narrowed to 15 millimeters or less because the light emitted from the light emitting device package sufficiently advances to the side by the action of the lens as described above, And the generation of dust can be prevented. Considering that the height d ₂ of the light emitting device package 200 including the lens 100 is about 7 millimeters, the distance d ₁ between the reflective sheet 435a and the optical sheet 421 is 10 millimeters The damage caused by the collision of the optical sheet 421 and the lens 100 can be prevented.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented.

Light emitting element: 200 Lens: 100
Lens housing: 101 Curvature radius: r
Display device: 400 bottom chassis: 435
Optical sheet: 420 Driving part: 455

Claims (10)

Board;
A light emitting element disposed on the substrate and emitting light; And
And a lens formed in surface contact with at least one surface of the light emitting device,
And the lens includes a curved surface for condensing the light emitted from the light emitting element toward a predetermined region. The method according to claim 1,
Wherein the curved surface is a concave surface concave toward the light emitting element. 3. The method of claim 2,
Wherein a radius of curvature of the concave surface is determined by a position of the light emitting element and the predetermined region or a refractive index of the lens. The method of claim 3,
Wherein the curvature radius of the concave surface is determined by the following equation.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens. The method according to claim 1,
And the refractive index of the lens is 1.41 to 1.53. A lens housing forming an appearance; And
And a concave surface that is concave toward at least one lower portion,
Wherein the concave surface has a radius of curvature in which the light emitted from the light emitting device disposed on the lower surface of the lens housing is condensed in a predetermined area. The method according to claim 6,
Wherein the concave surface of the lens is determined by the following equation.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens. 8. The method of claim 7,
Wherein the refractive index of the lens is 1.41 to 1.53. Bottom chassis;
An optical sheet disposed opposite to the bottom chassis,
A driving substrate;
At least one light emitting element disposed on the driving substrate; And
And a plurality of optical members for controlling light emitted from the at least one light emitting element,
Wherein the optical member comprises:
And a lens including at least one concave surface for condensing the light emitted from the light emitting device into a predetermined area. 10. The method of claim 9,
Wherein the concave surface of the lens is determined by the following equation.

Where a is the length of the optical path from the top surface of the light emitting element to the concave surface of the lens at the trace of the shortest distance at which the light emitted from the center of the light emitting element reaches the predetermined area, N 'is the refractive index in air, and n is the refractive index of the lens.

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