WO2016043464A1

WO2016043464A1 - Light emitting diode

Info

Publication number: WO2016043464A1
Application number: PCT/KR2015/009438
Authority: WO
Inventors: Seom Geun Lee; Mae Yi KIM; Kyoung Wan Kim; Yeo Jin Yoon; Keum Ju Lee
Original assignee: Seoul Viosys Co., Ltd.
Priority date: 2014-09-15
Filing date: 2015-09-08
Publication date: 2016-03-24

Abstract

Disclosed herein is a light-emitting diode including: a substrate; and at least two light-emitting cell groups positioned on the substrate and having a plurality of light-emitting cells connected to each other in series, in which the at least two light-emitting cell groups each are separately driven, spaced apart from each other at a predetermined interval to be insulated from each other, and have different areas and the light-emitting cell group includes: a plurality of light-emitting cells including first semiconductor layers, active layers, and second semiconductor layers and provided with grooves through which the first semiconductor layers are exposed; a first electrode disposed on the second semiconductor layer; an insulating layer covering the plurality of light-emitting cells to expose portions of the first electrode and the first semiconductor layer; and a connection electrode electrically connected to the exposed portions of the first electrode and first semiconductor layer.

Description

LIGHT EMITTING DIODE

The disclosed technology relates to a light emitting diode, and For example, to a light emitting diode which may be sequentially driven depending on a level of AC voltage by one light emitting diode.

A light emitting diode which may be driven under a high voltage by connecting a plurality of light emitting cells to each other in series within a single chip is disclosed in WO2004/023568(A1) entitled “LIGHT-EMITTING DEVICE HAVING LIGHT-EMITTING ELEMENTS” by SAKAI, et.al.

In general, the light emitting diode in which the plurality of light emitting cells are connected to each other in series is provided in plural to configure an AC driving lighting apparatus.

However, when being sequentially driven for a plurality of driving sections depending on a magnitude of input AC voltage, a general AC driving lighting apparatus needs to include at least one light emitting diode for each driving section. Further, the light emitting diode driven at a relatively low AC voltage needs to keep a predetermined driving current, and therefore the number of light emitting diodes driven at a relatively low AC voltage needs to be larger than the number of light emitting diodes driven at a high AC voltage. That is, the general AC driving lighting apparatus is hard to reduce the number of light emitting diodes.

An object of the disclosed technology is to provide a lighting apparatus capable of reducing the number of light emitting diode packages while keeping light efficiency.

Another object of the disclosed technology is to provide a lighting apparatus capable of reducing total manufacturing costs of a lighting apparatus.

Still another object of the disclosed technology is to provide a light emitting diode and a lighting apparatus which may be sequentially driven by only one light emitting diode package in a high driving voltage section.

According to an exemplary embodiment of the disclosed technology, there is provided a light emitting diode, including: a substrate; and at least two light emitting cell groups positioned on the substrate and having a plurality of light emitting cells connected to each other in series, in which the at least two light emitting cell groups may each be separately driven, are spaced apart from each other at a predetermined interval to be insulated from each other, and have different areas, and the light emitting cell group may include: the plurality of light emitting cells including first semiconductor layers, active layers, and second semiconductor layers and provided with grooves through which the first semiconductor layers are exposed; a first electrode disposed on the second semiconductor layer; an insulating layer covering the plurality of light emitting cells to expose portions of the first electrode and the first semiconductor layer; and a connection electrode electrically connected to the exposed portions of the first electrode and first semiconductor layer.

The at least two light emitting cell groups may be a first light emitting cell group having the plurality of light emitting cells connected to each other in series, a second light emitting cell group separately driven from the first light emitting cell group and having the plurality of light emitting cells connected to each other in series, and a third light emitting cell group separately driven from the first and second light emitting cell groups and having the plurality of light emitting cells connected to each other in series and the first light emitting cell group may have an area wider than those of the second and third light emitting cell groups.

The first light emitting cell group may be disposed between the second and third light emitting cell groups. The first and second light emitting cell groups may be adjacently arranged to each other. The first and second light emitting cell groups may be adjacently arranged to a central portion of the light emitting diode. The second light emitting cell group may have an area wider than that of the third light emitting cell group.

The at least two light emitting cell groups may be the first to third light emitting cell groups and a fourth light emitting cell group having a different area from those of the first to third light emitting cell groups.

The third and fourth light emitting cell groups may be adjacently arranged to edges of both sides of the light emitting diode and the first to fourth light emitting cell groups may be spaced apart from each other at a predetermined interval.

The second light emitting cell group may be disposed between the first and fourth light emitting cell groups.

The second light emitting cell group may have an area wider than that of the third light emitting cell group and the third light emitting cell group may have an area wider than that of the fourth light emitting cell group.

The first light emitting cell group may have a light emitting section longer than that of the second light emitting cell group. The second light emitting cell group may have a light emitting section longer than that of the third light emitting cell group. The third light emitting cell group may have a light emitting section longer than that of the fourth light emitting cell group.

The light emitting cell group may be driven by AC power and when a driving voltage of the AC power is increased, the number of light emitting cell groups emitting light of the at least two light emitting cell groups may be increased and when the driving voltage of the AC power is reduced, the number of light emitting cell groups emitting light of the at least two light emitting cell groups may be reduced.

The first electrode may include an ohmic layer ohmic-contacting the second semiconductor layer and a reflecting layer.

According to the light emitting diode according to the exemplary embodiments of the disclosed technology, the plurality of light emitting cell groups having different areas may be embedded in the single chip, may have a larger area as the driven forward voltage level is reduced, and may be adjacently arranged at the central portion of the light emitting diode, thereby implementing the uniform luminance on the whole and implementing the surface light and the illumination having various sizes by the standardized light emitting diode.

FIG. 1 is a diagram illustrating a configuration of an apparatus for driving a light emitting diode according to an exemplary embodiment of the disclosed technology.

FIG. 2 is a plan view illustrating a light emitting diode according to an exemplary embodiment of the disclosed technology.

FIG. 3 is a plan view illustrating light emitting cells of a light emitting diode according to an exemplary embodiment of the disclosed technology.

FIG. 4 is a cross-sectional view of the light emitting diode taken along line I-I’ of FIG. 3.

FIG. 5 is a waveform diagram illustrating a relationship of driving currents of the light emitting cells based on a four stage driving section depending on a driving voltage in a lighting apparatus according to an exemplary embodiment of the disclosed technology.

FIG. 6 is an exploded perspective view illustrating an example in which the light emitting diode according to the exemplary embodiment of the disclosed technology is applied to the lighting apparatus.

Hereinafter, exemplary embodiments of the disclosed technology will be described in detail with reference to the accompanying drawings. The exemplary embodiments of the disclosed technology to be introduced below are provided by way of example so that the idea of the disclosed technology can be sufficiently transferred to those skilled in the art to which the disclosed technology pertains. Therefore, the disclosed technology is not limited to exemplary embodiments to be described below, but may be implemented in other forms. In the accompanying drawings, widths, lengths, thicknesses, or the like, of components may be exaggerated for convenience. Like reference numerals denote like elements throughout the specification.

Further, a term ‘first forward voltage level (Vf₁)’ means a threshold voltage level that may drive a first light emitting cell group, a term ‘second forward voltage level (Vf₂)’ means a threshold voltage level that may drive first and second light emitting cell groups connected to each other in series, and a term ‘third forward voltage level (Vf₃)’ means a threshold voltage level that may drive first to third light emitting cell groups connected to each other in series. That is, ‘an n-th forward voltage level (Vf_n)’ means a threshold voltage level that may drive first to n-th light emitting cell groups connected to each other in series. Meanwhile, forward voltage levels of each light emitting device group may be the same as each other or different from each other depending on the number/characteristics of light emitting devices configuring the light emitting cell groups.

Further, a term ‘sequential driving scheme’ means a driving scheme of letting a plurality of light emitting device groups sequentially emit light as a driving voltage in which an AC voltage (input voltage) is rectified is increased and letting a plurality of light emitting device groups sequentially be turned out as an input voltage is reduced, in a lighting apparatus receiving the AC voltage of which the magnitude is changed over time to drive the light emitting diode.

As illustrated in FIG. 1, an apparatus for driving a light emitting diode 100 according to an exemplary embodiment of the disclosed technology may include an AC power supply, a rectifier, a driving module, and the light emitting diode 100.

The light emitting diode 100 may include a plurality of light emitting cell groups. For example, the light emitting diode 100 may include first to fourth light

emitting cell groups

110, 120, 130, and 140.

The rectifier rectifies an AC voltage from the AC power supply to generate a driving voltage and output the generated driving voltage. The rectifier is not particularly limited and one of various known rectifying circuits such as a full-wave rectifying circuit, a half-wave rectifying circuit, and the like, may be used. For example, the rectifier may be a bridge full-wave rectifying circuit configured of four diodes.

The driving module uses the driving voltage to control the light emitting diode 100. For example, a first driving module may sequentially drive first to fourth light

emitting cell groups

110, 120, 130, and 140 for a plurality of sections (first to seventh sections). The first section is defined as a section in which a voltage level of the driving voltage input from the rectifier is between a first forward voltage level and a second forward voltage level and only a first current path is connected for the first section and thus a first light emitting cell group 110 emits light.

Further, the second section is defined as a section in which the voltage level of the driving voltage input from the rectifier is between the second forward voltage level and a third forward voltage level and a second current path is connected for the second section and thus the first and second light

emitting cell groups

110 and 120 emit light.

Further, the third section is defined as a section in which the voltage level of the driving voltage input from the rectifier is between the third forward voltage level and a fourth forward voltage level and a third current path is connected for the third section and thus the first to third light

emitting cell groups

110, 120, and 130 emit light.

The fourth section is defined as a section in which the voltage level of the driving voltage input from the rectifier is equal to or more than the fourth forward voltage level and a fourth current path is connected for the fourth section and thus the first to fourth light

emitting cell groups

110, 120, 130, and 140 emit light.

Further, the fifth section is defined as a section in which the voltage level of the driving voltage input from the rectifier is between the fourth forward voltage level and the third forward voltage level and the third current path is connected for the fifth section and thus the first to third light

emitting cell groups

110, 120, and 130 emit light.

Further, the sixth section is defined as a section in which the voltage level of the driving voltage input from the rectifier is between the third forward voltage level and the second forward voltage level and the second current path is connected for the sixth section and thus the first and second light

emitting cell groups

110 and 120 emit light.

The seventh section is defined as a section in which the voltage level of the driving voltage from the rectifier is between the second forward voltage level and the first forward voltage level and only the first current path is connected for the seventh section and thus the first light emitting cell group 110 emits light.

Here, the first section and the seventh section may be defined as a first stage driving section, the second and sixth sections may be defined as a second stage driving section, and the third and fifth sections may be defined as a third stage driving section. Further, the fourth section may be defined as a fourth stage driving section. In this case, the first to fourth light

emitting cell groups

110, 120, 130, and 140 each may have different forward voltage levels. For example, when the first to fourth light

emitting cell groups

110, 120, 130, and 140 each include different number of light emitting cells, the first to fourth light

emitting cell groups

110, 120, 130, and 140 have different forward voltage levels.

The light emitting diode 100 according to the exemplary embodiment of the disclosed technology may include the first to fourth light

emitting cell groups

110, 120, 130, and 140 integrally embedded in a single chip to implement uniform luminance on the whole and implement surface light and illuminance having various sizes by the standardized single light emitting diode 100.

FIG. 2 is a plan view illustrating the light emitting diode 100 according to the exemplary embodiment of the disclosed technology. FIG. 3 is a plan view illustrating the light emitting cells of the light emitting diode 100 according to an exemplary embodiment of the disclosed technology and FIG. 4 is a cross-sectional view of the light emitting diode 100 taken along line I-I’ of FIG. 3.

As illustrated in FIG. 2, the light emitting diode 100 according to the exemplary embodiment of the disclosed technology may include the first to fourth light

emitting cell groups

110, 120, 130, and 140 which are separately driven by the sequential driving scheme. Here, the first to fourth light emitting

cell groups

110, 120, 130, and 140 may correspond to the first to fourth light emitting

cell groups

110, 120, 130, and 140 of FIG. 1.

The first to fourth light emitting

cell groups

110, 120, 130, and 140 may have different areas. The first light emitting cell group 110 may have an area larger than that of the second light emitting cell group 120, the second light emitting cell group 120 may have an area larger than that of the third light emitting cell group 130, and the third light emitting cell group may have an area larger than that of the fourth light emitting cell group 140.

The first and second light emitting

cell groups

110 and 120 may be adjacently arranged to a central portion of the light emitting diode 100 and the third and fourth light emitting

cell groups

130 and 140 each may be adjacently arranged to edges of the light emitting diode 100. In more detail, the first light emitting cell group 110 may be positioned between the second and third light emitting

cell groups

120 and 130, the second light emitting cell group 120 may be positioned between the first and fourth light emitting

cell groups

110 and 140, and the first and second light emitting

cell groups

110 and 120 may be adjacently arranged to each other.

In the light emitting diode 100, the first light emitting cell group 110 to the fourth light emitting cell group 140 may be sequentially driven and light may be emitted from a central region of the light emitting diode 100, thereby improving the appearance quality of the light emitting diode.

As illustrated in FIGS. 3 and 4, the light emitting diode 100 according to the exemplary embodiment of the disclosed technology may include the first to fourth light emitting

cell groups

110, 120, 130, and 140 having different sizes.

The first to fourth light emitting

cell groups

110, 120, 130, and 140 may have different areas, in which the first light emitting cell group 110 may have an area larger than that of the second light emitting cell group 120, the second light emitting cell group 120 may have an area larger than that of the third light emitting cell group 130, and the third light emitting cell group 130 may have an area larger than that of the fourth light emitting cell group 140.

The first and second light emitting

cell groups

130 and 140 may be adjacently arranged to the edges of the light emitting diode 100. In more detail, the first light emitting cell group 110 may be positioned between the second and third light emitting

cell groups

110 and 140, and the first and second light emitting

cell groups

110 and 120 may be adjacently arranged to each other.

In the light emitting diode 100, the first light emitting cell group 110 to the fourth light emitting cell group 140 may be sequentially driven and light may be emitted from the central region of the light emitting diode 100, thereby improving the appearance quality of the light emitting diode 100.

The first to fourth light emitting

cell groups

110, 120, 130, and 140 may be spaced apart from each other at a predetermined interval in a first direction and the plurality of light emitting cells may be electrically connected to each other in a second direction vertical to the first direction. A substrate may be exposed between the first to fourth light emitting

cell groups

110, 120, 130, and 140 by an etch process and the first to fourth light emitting

cell groups

110, 120, 130, and 140 may be manufactured in a state in which they are insulated from each other.

For example, describing the fourth light emitting cell group 140 with reference to FIG. 4, the third light emitting cell group may include a substrate, a plurality of light emitting cells, first electrodes 127, first insulating layers 131, second insulating layers 133, a third insulating layer 135, connection electrodes 129, first upper electrodes 171, and second upper electrodes 173.

The substrate may include materials such as sapphire, silicon carbide or GaN. Any material may be used for the substrate as long as it can induce the growth of the formed thin film.

The plurality of light emitting cells are formed on the substrate and may include first conductivity type semiconductor layers 124, active layers 126, and second conductivity type semiconductor layers 125. In this case, the first conductivity type semiconductor layer 124 may have an n-type conductivity type, the active layer 126 may have a multi-quantum well structure, and the second conductivity type semiconductor layer 125 may be formed on the active layer 126. According to the exemplary embodiment of the disclosed technology, if the first conductivity type semiconductor layer 124 has the n-type conductivity type, the second conductivity type semiconductor layer 125 may have a p-type conductivity type. Although not illustrated, if necessary, a buffer layer (not illustrated) may be additionally formed between the substrate and the first conductivity type semiconductor layer 124 to facilitate a single crystal growth.

Further, the plurality of light emitting cells are separated from each other while being spaced apart in a predetermined distance in one direction. In this case, the separated structure is etched up to the first conductivity type semiconductor layer 124, such that adjacent light emitting cells each may be spaced apart from each other. Further, the plurality of light emitting cells each may be provided with grooves through which portions of the first conductivity type semiconductor layers 124 are exposed at the central portions of the light emitting cells by the etch process.

The first electrode 127 may be disposed on the second conductivity type semiconductor layer 125. The first electrode 127 may include an ohmic layer and a reflecting layer, in which the ohmic layer may be formed of metal or a transparent electrode layer and any metal may be applied as long as it may ohmic-contact the second conductivity type semiconductor layer 125. Further, the reflecting layer may include metal such as Ag and Al.

The first insulating layer 131 is formed to cover the plurality of light emitting cells and the exposed substrate. When the ohmic layer and the reflecting layer are formed on the second conductivity type semiconductor layer 125, the first insulating layer 131 serves to protect the ohmic layer and the reflecting layer from being deposited at a mesa boundary surface. In this case, a thickness of the first insulating layer 131 may be about 1000 A.

The second insulating layer 133 may cover the first insulating layer 131 and cover a portion of the first electrode 127 including the ohmic layer and the reflecting layer and the exposed portion of the first conductivity type semiconductor layer 124. In this case, the first and second insulating

layers

131 and 133 may cover the exposed portion of the first conductivity type semiconductor layer 124, such that the connection electrode 129 may contact the first conductivity type semiconductor layer 124.

The connection electrode 129 may serve to electrically connect between the adjacent light emitting cells. In detail, the connection electrode 129 may electrically connect the first electrode 127 exposed on the light emitting cell positioned at one side to the first conductivity type semiconductor layer 124 exposed at the central portion of the light emitting cell positioned at the other side. That is, the connection electrode 129 contacts the first conductivity type semiconductor layer 124 while the connection electrode 129 fills a portion where the first and second insulating

layers

131 and 133 covering the mesa boundary surface of the groove formed at the central portion of the light emitting cell do not cover a portion of the first conductivity type semiconductor layer 124. Therefore, the connection electrode 129 covers the second insulating layer 133, the exposed first electrode 127, and the exposed first conductivity type semiconductor layer 124.

The third insulating layer 135 covers the connection electrodes 129 and covers the plurality of light emitting cells to expose portions of the first electrodes 127 positioned at sides of the plurality of light emitting cells and expose portions of the connection electrodes 129 positioned at other sides thereof.

The first and second

upper electrodes

171 and 173 are positioned on the third insulating layer 135, the first upper electrodes 171 are electrically connected to the first electrodes 127 exposed at sides of the plurality of light emitting cells, and the second upper electrodes 173 are electrically connected to the connection electrodes 129 exposed at the other sides of the plurality of light emitting cells.

In the light emitting diode 100 according to the exemplary embodiments of the disclosed technology, the first to fourth light emitting

cell groups

110, 120, 130, and 140 having different areas may be embedded in the single chip, may have a larger area as the driven forward voltage level is reduced, and may be adjacently arranged at the central portion of the light emitting diode 100, thereby implementing the uniform luminance on the whole and implementing the surface light and the illumination having various sizes by the standardized light emitting diode 100.

The first light emitting cell group of the light emitting diode is driven by a first driving current ILED1 at timing t1 when an input driving voltage VP reaches a first forward voltage level Vf₁.

The second light emitting cell group is driven by a second driving current ILED2 from timing t2 when a voltage level of the driving voltage VP further rises to reach a second forward voltage level Vf₂. In this case, the first light emitting cell group keeps the driving state since the driving voltage VP is equal to or more than the first forward voltage level Vf₁.

The third light emitting cell group is driven by a third driving current ILED3 at timing t3 when the voltage level of the driving voltage VP further rises to reach a third forward voltage level Vf₃. In this case, the first and second light emitting cell groups keep the driving state since the driving voltage VP is equal to or more than the second forward voltage level Vf₂.

The fourth light emitting cell group is driven by a fourth driving current ILED4 at timing t4 when the voltage level of the driving voltage VP further rises to reach a fourth forward voltage level Vf₄. In this case, the first to third light emitting cell groups keep the driving state since the driving voltage VP is equal to or more than the third forward voltage level Vf₃.

Further, the driving of the fourth light emitting cell group stops at timing t5 when the driving voltage VP reaches a maximum value over time and then the voltage level falls to be less than the fourth forward voltage level Vf₄ and the first to third light emitting cell group keep the driving state since the driving voltage VP is equal to or more than the third forward voltage level Vf₃.

The driving of the third light emitting cell group stops at timing t6 when the voltage level of the driving voltage VP falls over time to be less than the third forward voltage level Vf₃ and the first and second light emitting cell group keep the driving state since the driving voltage VP is equal to or more than the second forward voltage level Vf₂.

The driving of the second light emitting cell group stops at timing t7 when the voltage level of the driving voltage VP falls over time to be less than the second forward voltage level Vf₂ and the first light emitting cell group keeps the driving state since the driving voltage VP is equal to or more than the first forward voltage level Vf₁.

As described above, the exemplary embodiment of the disclosed technology describes a four stage driving section as an example. Here, the first to fourth light emitting cell groups embedded in the single chip are sequentially driven, thereby implementing the uniform luminance and implementing the surface light and the illumination having various sizes by the standardized light emitting diode.

Referring to FIG. 6, the lighting apparatus according to the exemplary embodiment of the disclosed technology may include a diffusion cover 1010, a light emitting diode module 1020, and a body part 1030.

The body part 1030 may accommodate the light emitting diode module 1020 and the diffusion cover 1010 may be disposed on the body part 1030 to cover an upper portion of the light emitting diode module 1020.

The body part 1030 may accommodate and support the light emitting diode module 1020 and may take any form as long as it may supply power to the light emitting diode module 1020. For example, as illustrated, the body part 1030 may include a body case 1031, a power supplier 1033, a power supply case 1035, and a power supply connection part 1037.

In this case, the power supplier 1033 may be accommodated in the power supply case 1035 to be electrically connected to the light emitting diode module 1020 and may include at least one IC chip. The IC chip may adjust, convert, or control characteristics of power supplied to the light emitting diode module 1020.

The power supply case 1035 may accommodate and support the power supplier 1033 and the power supply case 1035 in which the power supplier 1033 is accommodated may be positioned inside the body case 1031.

The power supply connection part 1037 may be disposed at a lower portion of the power supply case 1035 and may be connected to the power supply case 1035. Therefore, the power supply connection part 1037 may be electrically connected to the power supplier 1033 inside the power supply case 1035 and thus may serve as a passage through which external power may be supplied to the power supplier 1033.

The light emitting diode module 1020 may include a substrate 1023 and a light emitting diode 1021 disposed on the substrate 1023. The light emitting diode module 1020 may be disposed on the body case and may be electrically connected to the power supplier 1033.

Any substrate may be used as long as the substrate 1023 may support the light emitting diode 1021. For example, the substrate 1023 may be a printed circuit board including wirings. The substrate 1023 may be formed in a form corresponding to a fixed part on the body case 1031 so that it may be stably fixed to the body case 1031.

The diffusion cover 1010 may be disposed on the light emitting diode 1021 and may be fixed to the body case 1031 to cover the light emitting diode 1021. The diffusion cover 1010 may be made of a light transmitting material and a form and light transmittance of the diffusion cover 1010 may be controlled to control directional characteristics of the lighting apparatus. Therefore, the diffusion cover 1010 may be changed in various forms according to the purpose and applications of the lighting apparatus.

Although the detailed description of the disclosed technology is made with reference to the accompanying drawings, the foregoing exemplary embodiments are just described with reference to the preferred example of the disclosed technology and therefore the disclosed technology is not understood as being limited only to the exemplary embodiment and the scope of the disclosed technology is to be understood as the claims and the equivalent concept to be described below.

Claims

A light emitting diode, comprising:

a substrate; and

at least two light emitting cell groups positioned on the substrate and having a plurality of light emitting cells connected to each other in series,

wherein the at least two light emitting cell groups each are separately driven, are spaced apart from each other at a predetermined interval to be insulated from each other, and have different areas, and

the light emitting cell group includes:

the plurality of light emitting cells including first semiconductor layers, active layers, and second semiconductor layers and provided with grooves through which the first semiconductor layers are exposed;

a first electrode disposed on the second semiconductor layer;

an insulating layer covering the plurality of light emitting cells to expose portions of the first electrode and the first semiconductor layer; and

a connection electrode electrically connected to the exposed portions of the exposed first electrode and first semiconductor layer.
The light emitting diode of claim 1, wherein the at least two light emitting cell groups are a first light emitting cell group having the plurality of light emitting cells connected to each other in series, a second light emitting cell group separately driven from the first light emitting cell group and having the plurality of light emitting cells connected to each other in series, and a third light emitting cell group separately driven from the first and second light emitting cell groups and having the plurality of light emitting cells connected to each other in series, and

the first light emitting cell group has an area wider than those of the second and third light emitting cell groups.
The light emitting diode of claim 2, wherein the first light emitting cell group is disposed between the second and third light emitting cell groups.
The light emitting diode of claim 2, wherein the first and second light emitting cell groups are adjacently arranged to each other.
The light emitting diode of claim 2, wherein the first and second light emitting cell groups are adjacently arranged to a central portion of the light emitting diode.
The light emitting diode of claim 2, wherein the second light emitting cell group has an area wider than that of the third light emitting cell group.
The light emitting diode of claim 2, wherein the at least two light emitting cell groups are the first to third light emitting cell groups and a fourth light emitting cell group having a different area from those of the first to third light emitting cell groups.
The light emitting diode of claim 7, wherein the third and fourth light emitting cell groups are adjacently arranged to edges of both sides of the light emitting diode.
The light emitting diode of claim 7, wherein the first to fourth light emitting cell groups are spaced apart from each other at a predetermined interval.
The light emitting diode of claim 7, wherein the second light emitting cell group is disposed between the first and fourth light emitting cell groups.
The light emitting diode of claim 7, wherein the second light emitting cell group has an area wider than that of the third light emitting cell group, and

the third light emitting cell group has an area wider than that of the fourth light emitting cell group.
The light emitting diode of claim 7, wherein the first light emitting cell group has a light emitting section longer than that of the second light emitting cell group.
The light emitting diode of claim 7, wherein the second light emitting cell group has a light emitting section longer than that of the third light emitting cell group.
The light emitting diode of claim 7, wherein the third light emitting cell group has a light emitting section longer than that of the fourth light emitting cell group.
The light emitting diode of claim 1, wherein the light emitting cell group is driven by AC power, and

when a driving voltage of the AC power is increased, the number of light emitting cell groups emitting light of the at least two light emitting cell groups is increased and when the driving voltage of the AC power is reduced, the number of light emitting cell groups emitting light of the at least two light emitting cell groups is reduced.
The light emitting diode of claim 1, wherein the first electrode includes an ohmic layer ohmic-contacting the second semiconductor layer and a reflecting layer.