KR102396916B1 - Light emitting device - Google Patents

Abstract

A light emitting device is disclosed. The light emitting device, in the white light emitting device, includes a light emitting diode emitting light having a peak wavelength within the range of 415 to 435 nm and a wavelength converter positioned on the light emitting diode, wherein the wavelength converter has a peak wavelength in the red light band A first red phosphor and a second red phosphor emitting light, a green phosphor emitting light having a peak wavelength in a green light band, and a cyan phosphor emitting light having a peak wavelength in a cyan light band, the first red The phosphor and the second red phosphor are different materials, and the light emitted from the light emitting device has a CRI value of 90 or more.

Description

Light Emitting Device {LIGHT EMITTING DEVICE}

The present invention relates to a light emitting device, and more particularly, to a light emitting device having high color rendering and light quantity.

Recently, light emitting diodes have been used as new solid-state light sources in various fields such as lighting, display, and medicine. Such a light emitting diode may be applied to a light emitting device processed in the form of a light emitting diode package or a light emitting diode module to be suitable for the application field.

Since light emitting diodes generally emit light having a narrow peak wavelength at half maximum width, a plurality of active layers emitting light in various wavelength bands are required in one light emitting diode to implement white light with one light emitting diode. However, manufacturing a light emitting diode having a plurality of such active layers is very inefficient for technical and process reasons.

Accordingly, in order to implement a white light emitting device using a light emitting diode, a light emitting device including a light emitting diode and a phosphor that excites light emitted from the light emitting diode into light of a different wavelength band is generally used. In this case, white light may be realized by mixing the light emitted from the light emitting diode and the light excited by the phosphor.

Specifically, white light can be obtained by applying a yellow-green or yellow-emitting phosphor by absorbing a part of blue light as excitation light on a blue light emitting diode chip. Referring to Korean Patent Application Laid-Open No. 10-2004-0032456, a phosphor that emits yellow-green to yellow light as an excitation source is attached to a part of the light on a light-emitting diode chip that emits blue light, so that blue light emission of the light-emitting diode and yellow-green to yellow light emission of the phosphor are applied. Accordingly, a light emitting diode emitting white light is disclosed. However, since the white light emitting diode package using this method utilizes the light emission of the yellow phosphor, color rendering and color reproducibility are low due to the lack of spectrum in the green and red regions of the emitted light. Accordingly, this type of light emitting device has limitations in application to lighting or display fields.

In order to solve this problem, a light emitting diode is manufactured using a blue light emitting diode chip and green and red phosphors using blue light as excitation light. That is, white light having high color rendering can be realized through a mixture of blue light and green light and red light excited by blue light. However, in a light emitting device using a generally used blue light emitting diode chip emitting light having a wavelength of about 450 nm, when it is used as lighting, various side effects may occur to the human body. For example, inhibition of melatonin may result, thereby affecting circadian rhythms. For example, there is a high risk of having trouble sleeping.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting device having improved color rendering and light quantity.

A light emitting device according to an embodiment of the present invention includes a light emitting diode emitting light having a peak wavelength within a range of 415 to 435 nm and a wavelength conversion unit located on the light emitting diode in the white light emitting device, and the wavelength conversion The first red phosphor and the second red phosphor emitting light having a peak wavelength in the red light band, the green phosphor emitting light having a peak wavelength in the green light band, and cyan emitting light having a peak wavelength in the cyan light band a phosphor, wherein the first red phosphor and the second red phosphor are different materials, and light emitted from the light emitting device has a CRI value of 90 or more. Accordingly, a light emitting device having excellent color rendering and excellent light quantity can be provided.

The first red phosphor may include a phosphor represented by the formula A ₂ MF ₆ : Mn, wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce and NH ₄ , and the M is any one selected from the group consisting of Si, Ti, Nb and Ta.

The green phosphor may include a silicate-based phosphor.

The silicate-based phosphor may include a phosphor represented by the formula (Ba,Sr,Ca) ₂ SiO ₄ :EU.

The second red phosphor may include a CASN-based phosphor.

The CASN-based phosphor may include a phosphor represented by the formula (Sr,Ca)AlSiN ₃ : EU or CaAlSiN ₃ : EU.

The cyan phosphor may include a LuAG-based phosphor.

The LuAG-based phosphor is Lu ₃ Al ₅ O ₁₂ : Ce or some Al is substituted with another group 3 element Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is a group 3 element other than Al) chemical formula It may include a phosphor.

A mass ratio of the cyan phosphor to the green phosphor may be 8 to 9.9:0.1 to 2, and a mass ratio of the second red phosphor to the first red phosphor may be 2.5 to 5:7.5 to 5. When the above mass ratios are satisfied, a light emitting device having excellent color rendering and excellent light quantity may be provided.

The first red phosphor and the second red phosphor emit light having a wavelength of 600 to 660 nm, the green phosphor emits light having a wavelength of 520 to 550 nm, and the cyan phosphor emits light having a wavelength of 490 to 550 nm can be released

The wavelength converter may cover at least a portion of the light emitting diode.

A light emitting device according to another embodiment of the present invention is a white light emitting device, comprising: a light emitting diode emitting light having a peak wavelength within a range of 415 to 435 nm; and a wavelength conversion unit positioned on the light emitting diode, wherein the wavelength conversion unit is, A ₂ MF ₆ : First red phosphor represented by Mn chemical formula, (Sr,Ca)AlSiN ₃ : EU or CaAlSiN ₃ : EU chemical formula A second red phosphor represented by (Ba,Sr,Ca) ₂ SiO ₄ : a green phosphor represented by EU chemical formula, and Lu ₃ Al ₅ O ₁₂ : Lu ₃ (Al) in which Ce or some Al is substituted with another group III element ,X) ₅ O ₁₂ : Ce (X is a group 3 element other than Al) includes a cyan phosphor represented by the formula, wherein the mass ratio of the cyan phosphor to the green phosphor is 8 to 9.9: 0.1 to 2, and the second red A mass ratio of the phosphor to the first red phosphor may be 2.5 to 5: 7.5 to 5, wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce, and NH ₄ , and M is Si , Ti, Nb, and any one selected from the group consisting of Ta, wherein X is a group 3 element other than Al. Accordingly, a light emitting device having excellent color rendering and excellent light quantity can be provided.

A light emitting device according to another embodiment of the present invention is a white light emitting device, comprising: a light emitting diode emitting light having a peak wavelength within a range of 415 to 435 nm; and a wavelength converter positioned on the light emitting diode, the wavelength The conversion unit includes a red phosphor emitting light having a peak wavelength in the red light band, a green phosphor emitting light having a peak wavelength in the green light band, and a cyan phosphor emitting light having a peak wavelength in the cyan light band, the light emission The light emitted from the device may have a CRI value of 90 or more, and a light emitting device having a light amount change rate of Equation 1 above 100% may be provided.

[Equation 1]

Light intensity change rate (%) = [F ₁ /F ₀ ]×100

F ₁ : amount of light emitted from the light emitting device (lm)

F ₀ : phosphor, Lu ₃ Al ₅ O ₁₂ : Ce or some Al is substituted with another group 3 element Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is group 3 element other than Al) LuAG-based phosphor and (Sr,Ca)AlSiN ₃ : Light quantity (lm) of light emitted from a light emitting device having a wavelength change unit including only a CASN-based phosphor expressed by EU chemical formula

The light emitting device according to the present invention has high color rendering and can emit light having a high amount of light at the same time.

1 is a cross-sectional view for explaining a light emitting device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art to which the present invention pertains. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. In addition, when one component is described as being “on” or “on” another component, each component is different from each component as well as when each component is “immediately above” or “directly on” the other component. This includes cases where there is another component in between. Like reference numerals refer to like elements throughout.

1 is a cross-sectional view for explaining a light emitting device according to an embodiment of the present invention.

Referring to FIG. 1 , the light emitting device may include a light emitting diode 120 and a wavelength converter 130 , and further include a base 110 .

In this embodiment, the light emitting diode 120 may be disposed on the base 110 . The base 110 may be, for example, a housing as shown.

The housing may include a cavity opened upward, and the light emitting diode 120 may be mounted in the cavity. The side surface of the cavity may be formed to be inclined, so that light emitted from the light emitting diode 120 is reflected to improve the light emitting efficiency of the light emitting device of the present embodiment. Furthermore, a reflective material may be further disposed on the inner side surface of the cavity.

When the base 110 is formed as a housing, the housing is a general plastic including a polymer, ABS (acrylonitrile butadiene styrene), LCP (liquid crystalline polymer), PA (polyamide), IPS (polyphenylene sulfide) or TPE (thermoplastic elastomer) ), etc., or may be formed of metal or ceramic. However, the present invention is not limited thereto.

Also, the base 110 may include at least two lead terminals, and the lead terminals and the light emitting diode 120 may be electrically connected to each other. The lead terminal may allow the light emitting device to be connected to an external power source. The light emitting diode 120 may be positioned on the lead terminal.

On the other hand, the base 110 is not limited thereto, as long as it is a configuration capable of supporting the light emitting diode 120 is not limited, and may include various known configurations. For example, the base 110 may include a conductive or insulating substrate on which the light emitting diode 120 is mounted, such as a lead frame, a PCB, and a heat sink for emitting heat generated from the light emitting diode 120 , etc. may further include.

The light emitting diode 120 may include an n-type semiconductor layer and a p-type semiconductor layer to have a structure capable of emitting light through a combination of holes and electrons. The light emitting diode 120 may have a structure such as a horizontal type, a vertical type, or a flip chip type, and the configuration and shape of the light emitting diode 120 are not limited.

The light emitting diode 120 may emit light having a peak wavelength in the visible region, and in particular, may emit light having a peak wavelength located in a range of 415 to 435 nm. By including the light emitting diode 120 emitting light having a peak wavelength in the above-mentioned range, it is possible to prevent the reliability and luminous efficiency of the light emitting device from being deteriorated by the ultraviolet rays emitted from the light emitting diode, and also, about 450 nm It is possible to minimize the harm to the human body by minimizing the light in the wavelength band.

The wavelength converter 130 may be positioned on the light emitting diode 120 , and further, may at least partially cover the light emitting diode 120 , and further encapsulate the light emitting diode 120 . That is, the wavelength converter 130 may be located on the light emission path of the light emitting diode 120 .

The wavelength converter 130 may include a support part 131 , a red phosphor 135 , a green phosphor 137 , and a cyan phosphor 139 that are irregularly dispersed in the support part 131 .

The supporting part 131 is not limited as long as it is a material capable of supporting the phosphors 135 , 137 , and 139 , and may have a transparent or translucent characteristic. The supporting part 131 is formed of a polymer including, for example, at least one of a silicone-based, an epoxy-based, a PMMA (polymethyl methacrylate)-based, a PE (polyethylene)-based, and a PS (polystyrene) series. It may also be formed of an inorganic material such as glass.

When the supporting unit 131 is formed of a polymer material, the wavelength converting unit 130 may serve as an encapsulant for encapsulating the light emitting diode 120 in addition to converting the wavelength of light emitted from the light emitting diode 120 . there is. In addition, the wavelength conversion unit 130 may be located on the base 110 , and as in this embodiment, when the base 110 includes a cavity, the wavelength conversion unit 130 may be disposed within the cavity. . Furthermore, the upper surface of the wavelength converter 130 may be formed in various shapes, such as a convex lens shape, a flat plate shape (not shown), and a shape having predetermined irregularities on the surface. According to the present embodiment, the wavelength converter 130 has been disclosed as having a convex lens shape, but is not limited thereto.

The red phosphor 135 , the green phosphor 137 , and the cyan phosphor 139 may be irregularly dispersed in the supporting part 131 .

Specifically, the red phosphor 135 may excite the incident light to emit red light, the green phosphor 137 may excite the incident light to emit green light, and the cyan phosphor 139 may emit the incident light. can be excited to emit cyan light. Accordingly, in the light emitting device of the present invention, violet light emitted from the light emitting diode 120, red light excited by the red phosphor 135, green light excited by the green phosphor 137, and cyan phosphor 139 ), the cyan light excited by the color can be mixed to emit white light.

Meanwhile, white light emitted by the light emitting device of the present embodiment may have a CRI value of 90 or more.

The peak wavelength of the red light emitted from the red phosphor 135 may be located within a wavelength range of 600 to 660 nm. The red phosphor 135 includes a first red phosphor 133 and a second red phosphor 134 .

The first red phosphor 133 includes a phosphor represented by the formula A ₂ MF ₆ : Mn, wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce and NH ₄ , and the M is any one selected from the group consisting of Si, Ti, Nb and Ta. The first red phosphor 133 used in the present invention may have a peak wavelength in a wavelength range of 625 to 660 nm. The second red phosphor 134 may include a CASN-based phosphor. The CASN-based phosphor used in the present invention may have a peak wavelength in a wavelength range of 600 to 650 nm. The CASN-based phosphor may include a phosphor represented by the formula (Sr,Ca)AlSiN ₃ :EU or CaAlSiN ₃ :EU.

The green phosphor 137 may include a silicate-based phosphor. The silicate-based phosphor used in the present invention may have a peak wavelength in a wavelength range of 520 to 550 nm. The silicate-based phosphor may include a phosphor represented by the formula (Ba,Sr,Ca) ₂ SiO ₄ :EU.

The cyan phosphor 139 may include a LuAG-based phosphor. The LuAG-based phosphor used in the present invention may have a peak wavelength in a wavelength range of 490 to 550 nm. LuAG-based phosphor is Lu ₃ Al ₅ O ₁₂ : Ce or some Al is substituted with an element of the same group, for example, Ga, In, etc. Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is group 3 other than Al) element) may include a phosphor represented by the chemical formula. Specifically, the LuAG-based phosphor may include a phosphor represented by the formula Lu ₃ (Al,Ga) ₅ O ₁₂ : Ce in which some Al is substituted with Ga. In particular, the phosphor represented by the formula Lu ₃ (Al,Ga) ₅ O ₁₂ : Ce in which some Al is substituted with Ga may have a peak wavelength in a wavelength range of 490 to 520 nm, specifically, a peak wavelength of about 505 nm. may have

A mass ratio of the second red phosphor 134 to the first red phosphor 133 in the wavelength converter may be 2.5 to 5: 7.5 to 5. Specifically, the mass ratio of the phosphor expressed by the (Sr,Ca)AlSiN ₃ :EU or CaAlSiN ₃ :EU chemical formula in the wavelength conversion unit and the phosphor expressed by the A ₂ MF ₆ :Mn chemical formula is 2.5 to 5: 7.5 to 5. and wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce and NH ₄ , and M is any one selected from the group consisting of Si, Ti, Nb and Ta.

A mass ratio of the LuAG-based phosphor and the silicate-based phosphor in the wavelength conversion unit may be 8 to 9.9:0.1 to 2. Specifically, Lu ₃ Al ₅ O ₁₂ in the wavelength conversion unit: Ce or some Al is substituted with another group 3 element Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is group 3 element other than Al) chemical formula The mass ratio of the phosphor to be (Ba,Sr,Ca)2SiO4 _: EU and the phosphor expressed by the formula may be 8 to 9.9:0.1 to ₂ .

According to an embodiment of the present invention, a light emitting device having a CRI of 90 or more and excellent light quantity can be provided.

Specifically, in the white light emitting device according to the embodiment of the present invention, the rate of change in the amount of light in Equation 1 may be greater than 100%.

[Equation 1]

Light intensity change rate (%) = [F ₁ /F ₀ ]×100

F ₁ : amount of light emitted from the light emitting device (lm)

F ₀ : a phosphor, Lu ₃ (Al,Ga) ₅ O ₁₂ : a wavelength change part including only a LuAG-based phosphor expressed by the Ce formula and (Sr,Ca)AlSiN ₃ : a CASN-based phosphor represented by the EU formula Light quantity (lm) of light emitted from a light emitting device having

Examples and Comparative Examples

Example 1: Preparation of a light emitting device

Referring to FIG. 1 , as a light emitting diode emitting a peak wavelength of about 425 nm, a rectangular light emitting chip having a size of 860 μm×540 μm was mounted on a lead frame (not shown).

A housing having a cavity at the top of the lead frame was formed by transfer molding using EMC (Epoxy Molding Compound).

90% by weight of silicone resin based on the total weight of the wavelength conversion unit was mixed with the phosphor of the present invention to prepare a slurry, and then dropped into the cavity of the housing. Thereafter, a light emitting device including a wavelength conversion unit was manufactured by curing the silicone resin by heat treatment at a temperature of 150°C. In the above process, the phosphor was prepared in a required amount in advance so that the chromaticity (CIE) of the LED lamp falls within the range of x = 0.458 to 0.462 and y = 0.412 to 0.417, and slurry was prepared. In addition, in the process, the wavelength change part includes the second red phosphor expressed by the (Sr,Ca)AlSiN ₃ : EU chemical formula and the first red phosphor expressed by the K ₂ SiF ₆ : Mn chemical formula in a mass ratio of 4:6, and , Lu ₃ (Al,Ga) ₅ O ₁₂ : LuAG-based phosphor represented by the formula Ce and (Ba,Sr,Ca) ₂ SiO ₄ : silicate-based phosphor represented by the EU formula are included in a mass ratio of 9:1 prepared to do so.

Comparative Example 1: Preparation of a light emitting device

In Example 1, the second red phosphor represented by the (Sr,Ca)AlSiN ₃ :EU chemical formula and the first red phosphor represented by the K ₂ SiF ₆ :Mn chemical formula were mixed in a mass ratio of 7:3 rather than a mass ratio of 4:6. A light emitting device was prepared in the same manner as in Example 1, except that it was included.

Comparative Example 2: Preparation of a light emitting device

In Example 1, the second red phosphor represented by the (Sr,Ca)AlSiN ₃ :EU chemical formula and the first red phosphor represented by the K ₂ SiF ₆ :Mn formula were mixed in a mass ratio of 2:8, not a mass ratio of 4:6. A light emitting device was prepared in the same manner as in Example 1, except that it was included.

Comparative Example 3: Preparation of a light emitting device

In Example 1, except that the first red phosphor represented by the formula K ₂ SiF ₆ :Mn and the silicate-based phosphor represented by the (Ba,Sr,Ca) ₂ SiO ₄ :EU formula were not used. A light emitting device was manufactured in the same manner as in 1.

Experimental example

A power supply (a rated current of 100 mA, a voltage of 6.1 V) was supplied to the light emitting devices of Example 1 and Comparative Examples 1 to 3 to measure a CRI value, R9. In addition, by measuring the flux (lm) of Examples 1 and 1 to 3, the light amount change rate (Δ) of each Example and Comparative Example when the flux of Comparative Example 3 was 100% as a standard was expressed in %. These values are shown in Table 1 below.

CIE x CIE y L/Flux (lm) @equal CIE x,y CRI R9 Flux(lm) Δ(%) Example 1 0.460 0.413 71.0 71.7 104.4 91.1 40.0 Comparative Example 1 0.460 0.416 72.3 72.3 105.4 89.1 33.5 Comparative Example 2 0.460 0.416 67.9 67.9 99.0 94.5 60.2 Comparative Example 3 0.460 0.416 68.0 68.6 100 92.4 43.6

Referring to Table 1, the light emitting device according to the embodiment of the present invention has a CRI of 90 or more and a rate of change of light quantity (%) of 104.4%, so that the flux is increased compared to Comparative Example 3 in which the first red phosphor is not used. can confirm that On the other hand, Comparative Example 2 showed a CRI of 90 or more but a light amount change rate of 99.0%, confirming that the light amount was lowered. In Comparative Example 1, since the light amount change rate was 105.4%, there was a gain in the light amount, but the CRI was only 89.1, so it can be confirmed that the color rendering property is deteriorated. The numerical value of Comparative Example 3 is a criterion for evaluation, and confirmation of Comparative Example 3 is meaningless.

Claims (9)

A white light emitting device comprising:
a light emitting diode emitting purple light having a peak wavelength in the range of 415 to 435 nm; and
It includes a wavelength conversion unit located on the light emitting diode,
The wavelength converter converts first and second red phosphors emitting light having a peak wavelength in the red light band, a green phosphor emitting light having a peak wavelength in the green light band, and light having a peak wavelength in the cyan light band. and a cyan phosphor that emits;
The first red phosphor and the second red phosphor are different materials,
The light emitted from the light emitting device has a CRI value of 90 or more,
The wavelength band of the red light is 600 ~ 660 nm,
The wavelength band of the green light is 520 to 550 nm,
The wavelength band of the cyan light is 490 to 520 nm,
The first red phosphor is a phosphor represented by the formula A ₂ MF ₆ :Mn, and the second red phosphor is a CASN-based phosphor,
Wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce and NH4, wherein M is any one selected from the group consisting of Si, Ti, Nb and Ta,
The mass ratio of the second red phosphor to the first red phosphor is 2.5 to 5: 7.5 to 5,
The light emitting device emits white light by mixing the purple light, the red light, the green light, and the cyan light. The method according to claim 1,
The green phosphor is a light emitting device including a silicate-based phosphor. 3. The method according to claim 2,
The silicate-based phosphor is (Ba,Sr,Ca) ₂ SiO ₄ : A light emitting device that is a phosphor expressed by the EU chemical formula. The method according to claim 1,
The CASN-based phosphor is (Sr,Ca)AlSiN ₃ : EU or CaAlSiN ₃ : EU A light emitting device represented by a chemical formula. The method according to claim 1,
The cyan phosphor is a light emitting device including a LuAG-based phosphor. 6. The method of claim 5,
The LuAG-based phosphor is expressed by the formula: Lu ₃ Al ₅ O ₁₂ : Ce or some Al is substituted with another group 3 element Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is a group 3 element other than Al) A light-emitting device that is a phosphor. The method according to claim 1,
A mass ratio of the cyan phosphor to the green phosphor is 8 to 9.9:0.1 to 2. The method according to claim 1,
The wavelength converter covers at least a portion of the light emitting diode. A white light emitting device comprising:
a light emitting diode emitting purple light having a peak wavelength in the range of 415 to 435 nm; and
It includes a wavelength conversion unit located on the light emitting diode,
The wavelength converter includes a red phosphor emitting light having a peak wavelength in the red light band, a green phosphor emitting light having a peak wavelength in the green light band, and a cyan phosphor emitting light having a peak wavelength in the cyan light band,
The wavelength band of the red light is 600 ~ 660 nm,
The wavelength band of the green light is 520 to 550 nm,
The wavelength band of the cyan light is 490 to 520 nm,
The red phosphor includes a first red phosphor and a second red phosphor, which are different materials,
The first red phosphor is a phosphor represented by the formula A ₂ MF ₆ :Mn, and the second red phosphor is a CASN-based phosphor,
Wherein A is any one selected from the group consisting of Li, Na, K, Rb, Ce and NH4, wherein M is any one selected from the group consisting of Si, Ti, Nb and Ta,
The mass ratio of the second red phosphor to the first red phosphor is 2.5 to 5: 7.5 to 5,
The light emitting device emits white light by mixing the purple light, the red light, the green light, and the cyan light,
The light emitted from the light emitting device has a CRI value of 90 or more,
A light emitting device in which the rate of change of the amount of light of the following formula 1 is greater than 100%.
[Equation 1]
Light intensity change rate (%) = [F ₁ /F ₀ ]×100
F ₁ : amount of light emitted from the light emitting device (lm)
F ₀ : Fluorescent material, Lu ₃ Al ₅ O ₁₂ : Ce or some Al is substituted with other Group III elements Lu ₃ (Al,X) ₅ O ₁₂ : Ce (X is Group III element other than Al) LuAG-based phosphor and (Sr,Ca)AlSiN ₃ : Amount of light emitted from a light emitting device having a wavelength change unit containing only a CASN-based phosphor expressed by the EU chemical formula (lm)

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