KR20130128516A

KR20130128516A - Lighting device

Info

Publication number: KR20130128516A
Application number: KR1020120052286A
Authority: KR
Inventors: 손언호; 김영진; 김보람
Original assignee: 엘지이노텍 주식회사
Priority date: 2012-05-17
Filing date: 2012-05-17
Publication date: 2013-11-27

Abstract

An embodiment relates to a lighting device.
Illumination apparatus according to the embodiment, the light source including a light emitting element; And an excitation layer disposed on the light source unit, wherein the excitation layer comprises: a first phosphor layer disposed on the light emitting element and having a first phosphor; And a second phosphor layer disposed on the first phosphor layer and having a second phosphor, wherein the excitation wavelength band of the first phosphor is longer than the excitation wavelength band of the second phosphor.

Description

LIGHTING DEVICE

An embodiment relates to a lighting device.

Light emitting diodes are known semiconductor devices that convert current into light. Various light emitting diodes have been used in various fields for a wide variety of purposes. More specifically, the light emitting diode is a semiconductor device that emits light (ultraviolet light, visible light, or infrared light) when a potential difference is applied across the p-n junction structure.

Light emitting diodes generate light by exciting electrons across the band gap between the conduction and valence bands of the semiconductor active (light emitting) layer. The electron transition generates light of a wavelength that varies with the band gap. Therefore, the color (wavelength) of the light emitted by the light emitting diode depends on the semiconductor material of the active layer of the light emitting diode.

The embodiment provides a lighting device that can improve color quality.

In addition, the embodiment provides a lighting device that can resolve the user's rejection.

In addition, the embodiment provides a lighting apparatus that can compensate for the luminous flux degradation by the excitation layer.

Illumination apparatus according to the embodiment, the light source including a light emitting element; And an excitation layer disposed on the light source unit, wherein the excitation layer comprises: a first phosphor layer disposed on the light emitting element and having a first phosphor; And a second phosphor layer disposed on the first phosphor layer and having a second phosphor, wherein the excitation wavelength band of the first phosphor is longer than the excitation wavelength band of the second phosphor.

Illumination apparatus according to the embodiment, the light source including a light emitting element; And an excitation layer disposed on the light source unit and having at least two phosphor layers, each of the phosphor layers including at least one or more of a yellow phosphor, a green phosphor, and a red phosphor; The emission wavelength band of the phosphor contained in the phosphor layer disposed closest to the light emitting element is longer than the excitation wavelength band of the phosphor contained in the phosphor layer disposed farthest from the light emitting element.

Illumination apparatus according to the embodiment, the light source including a light emitting element; An excitation layer disposed on the light source unit; And an optical film disposed on the excitation layer and having a diffusing material for diffusing light, wherein, in the state where the light emitting device is turned off, the b * value at the top surface of the optical film based on the CIE LAB color space is Greater than or equal to 0 and less than or equal to 30.

Illumination apparatus according to the embodiment, the light source including a light emitting element; An excitation layer disposed on the light source unit; And an optical film disposed on the excitation layer and having a diffusing material for diffusing light, wherein the b * value at an upper surface of the optical film is based on a CIE LAB color space while the light emitting device is turned off. When larger than 30, the difference value ((DELTA) b *) is larger than 1.5 for b * value in the upper surface of the said optical film, and b * value in the lower surface of the said excitation layer.

Using the lighting apparatus according to the embodiment, since the color coordinates are not dispersed and the color temperature can be controlled, there is an advantage in that the color quality can be improved.

In addition, there is an advantage that can resolve the user's rejection by the unique color of the excitation layer.

In addition, there is an advantage that can compensate for the luminous flux decrease by the excitation layer.

1 is a cross-sectional view of a lighting device according to an embodiment.
FIG. 2 is an enlarged view enlarging A shown in FIG. 1; FIG.
Figure 3 is a graph showing the excitation wavelength curve (Ex) and the emission wavelength curve (Em) of the yellow phosphor (Yellow), green phosphor (Green) and red phosphor (Red).
4 is a graph for explaining the effect of the lighting device shown in FIG.
5 is a cross-sectional view of a lighting device according to another embodiment.
FIG. 6 is an enlarged view of B shown in FIG. 5. FIG.
Figure 7 is a photograph showing a conventional excitation layer.
8 to 9 are diagrams for explaining the CIE LAB color space.
FIG. 10 is a graph showing luminance according to wavelengths of light emitted from the lighting device shown in FIG. 1 and the lighting device shown in FIG. 5.

The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. In addition, the size of each component does not necessarily reflect the actual size.

In the description of embodiments according to the present invention, it is to be understood that where an element is described as being formed "on or under" another element, On or under includes both the two elements being directly in direct contact with each other or one or more other elements being 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.

Hereinafter, an excitation layer and an illumination device including the same according to an embodiment will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a lighting apparatus according to an embodiment.

Referring to FIG. 1, the lighting apparatus 100 according to an embodiment includes a heat sink 110, a light source unit 130, a reflector 150, an optical plate 170, and an excitation layer 190. can do.

The radiator 110 may receive heat emitted from the light source unit 130 and emit the heat.

The heat sink 110 has one surface on which the light source unit 130 is disposed. Here, the surface may be a flat surface or may be a surface having a predetermined curvature.

The radiator 110 may be combined with the reflector 150. Specifically, the outer portion of the heat sink 110 may be combined with the lower end of the reflector 150.

The heat sink 110 may have a plurality of heat radiation fins (not shown). The heat dissipation fins (not shown) may protrude or extend outward from one side of the heat dissipator 110. Since the heat dissipation fins (not shown) widen the heat dissipation area of the heat dissipator 110, heat dissipation efficiency may be improved.

The heat sink 110 may be a metal material or a resin material having excellent heat dissipation efficiency. The heat sink 110 may be made of a material having high thermal conductivity (generally 150Wm-1K-1 or more, more preferably 200Wm-1K-1 or more). For example, it may be copper (about 400 Wm-1K-1 thermal conductivity), aluminum (about 250 Wm-1K-1 thermal conductivity), anodized aluminum, aluminum alloy, magnesium alloy. In addition, metal loaded plastic materials, such as polymers, for example epoxy or thermally conductive ceramic materials (e.g., aluminum silicon carbide (AlSiC) (thermal conductivity of about 170 to 200 Wm-1K-1) Can be).

The light source unit 130 is disposed on the heat sink 110. In detail, the light source unit 130 may be disposed on one surface of the heat sink 110. The light source unit 130 may emit predetermined light onto the radiator 110.

The light source unit 130 may include a substrate 131 and a light emitting element 133.

The substrate 131 may be any one of a general PCB, a metal core PCB (MCPCB), a standard FR-4 PCB, or a flexible PCB. The substrate 131 may directly contact the heat sink 110. The substrate 131 may be disposed on one surface of the heat sink 110.

At least one light emitting device 133 is disposed on the substrate 131.

In order to easily reflect light from the light emitting element 133 onto the substrate 131, a light reflecting material may be coated or deposited.

The substrate 131 may optionally have a heat dissipation tape or a heat dissipation pad or the like for structural purposes and / or to improve heat transfer to the heat dissipation 110. The heat dissipation tape and the heat dissipation pad may be disposed between the substrate 131 and one surface of the heat dissipator 110.

The light emitting elements 133 may be disposed on the substrate 131. The plurality of light emitting devices 133 may emit light of the same wavelength and emit light of different wavelengths. In addition, the plurality of light emitting devices 133 may emit light of the same color and may emit light of different colors.

The light emitting device 133 may be any one of a blue light emitting device emitting blue light, a green light emitting device emitting green light, a red light emitting device emitting red light, and a white light emitting device emitting white light.

The light emitting device 133 may be a light emitting diode (LED) chip. In addition, the LED chip 133 may be any one of a blue LED chip emitting blue light in the visible light spectrum, a green LED chip emitting green light, and a red LED chip emitting red light. Here, the blue LED chip has the main wavelength in the range of about 430nm to 480nm, the green LED chip has the main wavelength in the range of about 510nm to 535nm, and the red LED chip emits light having the main wavelength in the range of about 600nm to 630nm. .

The reflector 150 reflects light from the light source unit 130 in the direction of the optical plate 170.

The reflector 150 may surround the light source unit 130, and may easily reflect light from the light source unit 130 to the excitation layer 190.

The reflector 150 may have a reflecting surface that reflects light from the light source unit 130. The reflective surface may be substantially perpendicular to the substrate 131, or may form an obtuse angle with an upper surface of the substrate 131. The reflective surface may be coated or deposited with a material that can easily reflect light.

The optical plate 170 may be disposed on the light source unit 130 and disposed on the reflector 150. The outer portion of the optical plate 170 may be coupled to the upper end of the reflector 150.

The optical plate 170 may be a transparent or translucent plate made of plastic resin or glass.

The excitation layer 190 may be disposed on the bottom surface of the optical plate 170.

The optical plate 170 may be emitted from the light source unit 130 to transmit the light passing through the excitation layer 190 as it is. Here, the optical plate 170 may include a light diffusing material to diffuse the transmitted light.

The excitation layer 190 may be disposed on the optical plate 170. In detail, the excitation layer 190 may be disposed on at least one of an upper surface and a lower surface of the optical plate 170.

An adhesive material for adhesion to the optical plate 170 may be applied to the top or bottom surface of the excitation layer 190.

The excitation layer 190 may emit excitation light excited by the light emitted from the light source unit 130. Specifically, when the light emitted from the light source unit 130 reaches the excitation layer 190, the excitation layer 190 transmits some of the reached light as it is and emits excitation light excited by the remaining light. Can be. Here, the wavelength band of the excitation light is different from the wavelength band of the light emitted from the light source unit 130.

The excitation layer 190 may include at least one or more of a yellow phosphor, a green phosphor, and a red phosphor.

The yellow phosphor is excited by light of 500 nm or less emitted from the light source unit 130 to emit light having a peak wavelength in the band 530 nm to 580 nm. The yellow phosphor may be a silicate-based, garnet-based yag, or oxynitride-based phosphor. The yellow phosphor may emit light having a main wavelength in the range of 555 nm to 585 nm in response to blue light. The yellow phosphor may be selected from phosphors selected from Y 3 Al 5 O 12: Ce 3+ (Ce: YAG), CaAlSiN 3: Ce 3+, Eu 2+ -SiAlON series, and / or BOSE series. The yellow phosphor can also be doped to any suitable level to provide light output of the desired wavelength. Ce and / or Eu may be doped into the phosphor at a dopant concentration ranging from about 0.1% to about 20%. Suitable phosphors include products of Mitsubishi Chemical Company (Tokyo, Japan), Leuchtstoffwerk Breitungen GmbH (Breitungen, Germany) and Intermatix Company (Frefornia, California).

The green phosphor is excited by light of 400 nm or less emitted from the light source unit 130 to emit light having a main wavelength in the 450 nm to 530 nm band. The green phosphor may be a silicate-based, nitride-based, or oxynitride-based phosphor.

The red phosphor is excited by light of 580 nm or less emitted from the light source unit 130 to emit light having a main wavelength in the 600 nm to 650 nm band. The red phosphor may be a nitride or sulfide phosphor. Red phosphors may include CaAlSiN 3: Eu 2+ and Sr 2 Si 5 N 8: Eu 2+. This phosphor can maintain quantum efficiency at 80% or more at a temperature of 150 ° C or more. Other red phosphors that may be used include phosphors selected from CaSiN2: Ce3 +, CaSiN2: Eu2 + as well as the Eu2 + -SiAlON phosphor family, and / or phosphors selected from the (Ca, Si, Ba) SiO4: Eu2 + (BOSE) series. In particular, the CaAlSiN: Eu 2+ phosphor from Mitsubishi Chemical Company may have a dominant wavelength of about 624 nm, a peak wavelength of about 628 nm and an FWHM of about 100 nm.

The excitation layer 190 may be made of a plurality of phosphor layers. It will be described in detail with reference to FIG.

FIG. 2 is an enlarged view enlarging A illustrated in FIG. 1.

Referring to FIG. 2, the excitation layer 190 may include a plurality of phosphor layers 191, 193, and 195. The second phosphor layer 193 is disposed on the first phosphor layer 191, and the third phosphor layer 195 is disposed on the second phosphor layer 193. Light emitted from the light source unit 130 firstly passes through the first phosphor layer 191 and sequentially passes through the second phosphor layer 193 and the third phosphor layer 195.

The first to second phosphor layers 191, 193, and 195 may have at least one phosphor. Specifically, the first phosphor layer 191 has one of yellow, green and red phosphors, the second phosphor layer 193 also has one of yellow, green and red phosphors, and the third phosphor layer 195 is also yellow. It may have one of green, red phosphors. The number of cases that the first to third phosphor layers 191, 193, and 195 may have is as follows.

<1> The first phosphor layer 191 has a yellow phosphor, the second phosphor layer 193 has a green phosphor, and the third phosphor layer 195 has a red phosphor.

<2> The first phosphor layer 191 has a green phosphor, the second phosphor layer 193 has a red phosphor, and the third phosphor layer 195 has a yellow phosphor.

The first phosphor layer 191 has a red phosphor, the second phosphor layer 193 has a yellow phosphor, and the third phosphor layer 195 has a green phosphor.

Here, the color quality of each of <1> to <3> may be different. The best color quality among <1> to <3> is the case of <3>. This may be due to the difference between the 'excitation wavelength band' and the 'emission wavelength band' of each of the yellow, green, and red phosphors. Here, the excitation wavelength band has a peak wavelength in the band, and the emission wavelength band has a peak wavelength in the band. Specifically, it will be described with reference to FIG.

FIG. 3 is a graph showing excitation wavelength curves Ex and emission wavelength curves Em of yellow phosphors, green phosphors, and red phosphors, Red.

2 to 3, in the case of <1>, since the emission wavelength band of the yellow phosphor of the first phosphor layer 191 is 530 nm to 580 nm, the light emitted from the yellow phosphor of the first phosphor layer 191 Some may be used as excitation light of the red phosphor of the third phosphor layer 195. Therefore, not all of the light emitted from the yellow phosphor is emitted from the excitation layer 190, but part of it is emitted.

In the case of <2>, since the emission wavelength band of the green phosphor of the first phosphor layer 191 is 450 nm to 530 nm, a part of the light emitted from the green phosphor of the first phosphor layer 191 is the second phosphor layer 193. It can be used as excitation light of the red phosphor. Therefore, not all of the light emitted from the green phosphor is emitted from the excitation layer 190, but part of the excitation layer 190 is emitted.

In the case of <3>, since the emission wavelength band of the red phosphor of the first phosphor layer 191 is 600 nm to 650 nm, the light emitted from the red phosphor of the first phosphor layer 191 is transferred to the second phosphor layer 193. It cannot be used as excitation light of the yellow phosphor or the green phosphor of the third phosphor layer 195. Therefore, since all of the light emitted from the yellow, green, and red phosphors are emitted from the excitation layer 190 as in <3>, color coordinates are less dispersed and accurate colors than in the case of <1> to <2>. Color quality has a good advantage.

Therefore, when the excitation layer 190 is composed of a plurality of phosphor layers, and the plurality of phosphor layers has one phosphor, the excitation wavelength band is a short wavelength band of the phosphor layer of which the excitation wavelength band is a long wavelength band of the plurality of phosphor layers. The closer to the light source 130 than the phosphor layer, the color quality may be improved. In addition, as the phosphor layer having the long emission wavelength band is disposed closer to the light source 130 than the phosphor layer having the emission wavelength band, the color quality may be improved. In addition, if the emission wavelength band of the light emitted from the phosphor contained in the phosphor layer disposed closest to the light source unit 130 does not overlap the excitation wavelength band of the phosphor contained in the phosphor layer disposed furthest from the light source unit 130, the color quality is high. Can be improved.

Although not shown in the drawings, some phosphor layers of the first to third phosphor layers may be disposed on the lower surface of the optical plate 170, and the remaining phosphor layers may be disposed on the upper surface of the optical plate 170.

4 is a graph for explaining the effect of the lighting apparatus shown in FIG. 4 is a graph in the case where the excitation layer 190 of the lighting device 100 is above. In the graph of FIG. 4, the horizontal axis represents wavelength, the vertical axis represents luminous intensity, and the driving current of the light source unit 130 is 350 mA.

Referring to FIG. 4, as the junction temperature increases by 25 ° C., the luminous intensity drops at a constant rate. If the excitation layer 190 has the stacking order of the above <1> or <2>, the fall ratio of the brightness becomes larger.

5 is a cross-sectional view of a lighting device according to another embodiment.

The illumination device 100 ′ shown in FIG. 5 further includes an optical film 180 in the illumination device 100 shown in FIG. 1. Therefore, the radiator 110, the light source 130, the reflector 150, the optical plate 170, and the excitation layer 190 of the lighting apparatus 100 ′ shown in FIG. 5 are replaced with the above descriptions.

FIG. 6 is an enlarged view of B illustrated in FIG. 5.

5 to 6, the optical film 180 is disposed between the optical plate 170 and the excitation layer 190. The optical film 180 may be a transparent or translucent film having a transmittance of 30% or more and having a diffusing function. By the optical film 180, it is possible to remove the user's rejection due to the unique color of the excitation layer 190.

7 is a photograph showing a conventional excitation layer.

Referring to Fig. 7, the conventional excitation layer used in the conventional lighting device has a unique color. This is due to the color of the phosphor included in the conventional excitation layer. The color of the conventional excitation layer is mainly orange or yellow. This color gives the user a sense of rejection when a lighting device having a conventional excitation layer is turned off and can cause a mismatch with the surrounding interior.

The lighting apparatus 100 ′ shown in FIGS. 5 to 6 uses the optical film 180 and may allow the user to recognize the excitation layer 190 as a neutral color under a predetermined condition. In addition, it is possible to compensate for the luminous flux degradation caused by the excitation layer 190. Hereinafter, the predetermined condition will be described in detail.

The predetermined condition may be defined using the CIE LAB Perceptual Color Space. Reference is made to FIGS. 8 to 9.

8 through 9 are diagrams for describing the CIE LAB color space.

8 to 9, the CIE LAB color space is a standardized three-dimensional color coordinate system defined in the CIE. The color coordinates in the CIE LAB color space are represented by L *, a *, b *, where L * is the brightness, a * is the degree of green and red, b * is the yellow and blue ) Degree. For example, a * = 80 looks more red than a * = 50, and b * = 50 looks more yellow than b * = 20. Since colors are represented as dots in the CIE LAB color space, the color difference (ΔE *) in the CIE LAB color space is represented by displaying two color objects in their color coordinates and calculating the three-dimensional distance between the two points. You can get it. The CIE LAB color space digitizes colors so that you can predict and accurately reproduce colors without looking at them.

The predetermined condition using the CIE LAB spatial color space is that the b * value on the upper surface of the optical film 180 is greater than or equal to 0 and less than or equal to 30 (0 ≦ b * ≦ 30). Under the above conditions, the user may recognize the excitation layer 190 as a neutral color. Here, the upper surface of the optical film 180 may mean a surface in contact with the optical plate 170 in the optical film 180, when the optical plate 170 and the optical film 180 are integral, the optical film 180 ) May be an upper surface of the optical plate 170.

On the other hand, if the b * value of the upper surface of the optical film 180 is greater than 30, the predetermined condition is the difference between the b1 * value of the upper surface of the optical film 180 and the b2 * value of the lower surface of the excitation layer 190 ( Δb *) is greater than or equal to 1.5 (Δb * ≧ 1.5). Under the above conditions, the user may recognize the excitation layer 190 as a neutral color. Here, the lower surface of the excitation layer 190 is a surface on which the light emitted from the light emitting element 133 of the light source unit 130 is incident on the excitation layer 190.

Table 1 below is a table comparing light emitted from the lighting device 100 shown in FIG. 1 and the lighting device 100 ′ shown in FIG. 5. The light emitting device 133 of the lighting device 100 of FIG. 1 and the lighting device 100 ′ of FIG. 5 is an LED having a Wp of 445 nm.

Lm (beam) Lm / Wrad X (color coordinates) Y (color coordinates) CCT CRI 100 954.39 157.64 0.4108 0.3759 3273 82 100 ' 951.23 157.11 0.4166 0.3841 3224 83

FIG. 10 is a graph showing light intensity according to a wavelength of light emitted from the lighting device 100 shown in FIG. 1 and the lighting device 100 ′ shown in FIG. 5.

10 is a graph of the lighting device 100 of FIG. 1, and a red curve is a graph of the lighting device 100 ′ of FIG. 5.

When the above Table 1 and FIG. 10 are combined, as compared with the lighting apparatus 100 of FIG. 1, even if the lighting apparatus 100 ′ of FIG. 5 has a predetermined condition with the optical film 180, FIG. It can be seen that there is no significant difference in the lighting device 100 and the optical characteristics of 1. Accordingly, the lighting device 100 ′ of FIG. 5 has an optical property similar to that of the lighting device 100 of FIG. 1, and a user may not feel a rejection by the excitation layer 190.

On the other hand, when the optical film 180 shown in FIG. 5 has a diffusing material, the illumination device 100 ′ of FIG. 5 compensates for the decrease in luminous flux due to the excitation layer 190 than the illumination device 100 shown in FIG. 1. can do.

Meanwhile, the optical film 180 and the optical plate 170 may be integrated. That is, the optical plate 170 may have a function of the optical film 180. In this case, the above descriptions regarding the optical film 180 may be applied to the optical plate 170 as it is.

Meanwhile, the excitation layer 190 illustrated in FIGS. 1 to 4 may be applied to the lighting apparatus illustrated in FIG. 5 as it is.

Although the above description has been made with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those of ordinary skill in the art to which the present invention pertains should not be exemplified above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

110: heat sink
130: light source
150: reflector
170: optical plate
180: optical film
190: here

Claims

A light source unit including a light emitting element; And
And an excitation layer disposed on the light source unit.
The excitation layer is,
A first phosphor layer disposed on the light emitting element and having a first phosphor; And
And a second phosphor layer disposed on the first phosphor layer and having a second phosphor.
The excitation wavelength band of the said 1st fluorescent substance is longer wavelength band than the excitation wavelength band of the said 2nd fluorescent substance.

The method of claim 1, wherein the excitation layer,
A third phosphor layer disposed on the second phosphor layer and having a third phosphor;
The excitation wavelength band of the said 2nd phosphor is longer wavelength band than the excitation wavelength band of the said 3rd phosphor.

A light source unit including a light emitting element; And
And an excitation layer disposed on the light source unit and having at least two phosphor layers.
Each of the phosphor layers comprises at least one or more of a yellow phosphor, a green phosphor, and a red phosphor;
And an emission wavelength band of the phosphor included in the phosphor layer disposed closest to the light emitting element among the phosphor layers is a longer wavelength band than an excitation wavelength band of the phosphor contained in the phosphor layer disposed furthest from the light emitting element.

The method according to any one of claims 1 to 3,
Further comprising an optical plate disposed on the light source portion,
And the excitation layer is disposed on at least one of an upper surface and a lower surface of the optical plate.

A light source unit including a light emitting element;
An excitation layer disposed on the light source unit; And
And an optical film disposed on the excitation layer and having a diffusing material for diffusing light.
And the b * value on the top surface of the optical film with respect to the CIE LAB color space with the light emitting element turned off.

A light source unit including a light emitting element;
An excitation layer disposed on the light source unit; And
And an optical film disposed on the excitation layer and having a diffusing material for diffusing light.
When the light emitting device is turned off, when the b * value on the top surface of the optical film is greater than 30 based on the CIE LAB color space, the b * value on the top surface of the optical film and the b * on the bottom surface of the excitation layer Lighting device with a difference value Δb * greater than 1.5.

The method according to claim 5 or 6,
And an optical plate disposed on an upper surface of the optical film.

The method of claim 7, wherein
And said optical film and said optical plate are integral.

The method according to claim 5 or 6,
The excitation layer has at least two phosphor layers,
And an emission wavelength band of the phosphor included in the phosphor layer disposed closest to the light emitting element among the phosphor layers is a longer wavelength band than an excitation wavelength band of the phosphor contained in the phosphor layer disposed furthest from the light emitting element.