JP5886070B2 - Phosphor and light emitting device - Google Patents

Description

The present invention relates to a phosphor used for an LED (Light Emitting Diode) and a light emitting device using the LED.

As a phosphor used in a white light emitting device, there is a combination of β sialon and a red light emitting phosphor (see Patent Document 1), and there is a phosphor in which a red light emitting phosphor having a specific color coordinate and a green light emitting phosphor are combined. (See Patent Document 2). On the other hand, there is also a method of obtaining white color using a yttrium aluminum garnet (hereinafter referred to as YAG) phosphor which is a yellow phosphor (see Patent Document 3). In order to distinguish from the former, such white is called “pseudo white”. A light emitting device using “pseudo white” can easily obtain high luminance, but has poor color rendering. Further, both are required to have a small decrease in luminance when used at high temperatures or for a long period of time.

JP 2007-180483 A JP 2008-166825 A Japanese Patent No. 3503139

An object of the present invention is to provide a phosphor having improved color rendering and reliability without impairing its high-luminance emission as compared with a YAG phosphor. A white light emitting device using this phosphor is provided. It is to provide.

The present invention is a Ce-activated La system having a peak wavelength of 536 nm excited by light of 455 nm, a fluorescence intensity of 150% expressed as a relative value with the peak height of a standard sample (YAG) being 100%, and a half-value width of 111 nm. A phosphor of silicon nitride (A) , a peak wavelength of 544 nm excited with 455 nm light, and a β sialon with a fluorescence intensity of 288% , which is expressed as a relative value with the peak height of the standard sample (YAG) as 100%. It has a certain oxynitride phosphor (B) and a nitride phosphor (C) which is SCASN having a peak wavelength of 620 nm excited by 455 nm light, and the blending ratio of the phosphor (A) is 39 mass% or more and 72 mass% %, The blending ratio of the phosphor (B) is 13.6 mass% to 45 mass%, the blending ratio of the phosphor (C) is 10 mass% to 20 mass%, and the phosphor ( A) Total is the phosphor is at least 88 mass% of (B) and (C).

The phosphor is preferably blended so that 1 ≦ a / b ≦ 4 when the blending ratio a of the phosphor (A) and the blending ratio b of the phosphor (B) are set.

La based silicon nitride phosphor (A) is Ce-activated phosphor (B) is β-sialon phosphor (C) is SCASN.

An invention from another viewpoint of the present application is a light emitting device including the above-described phosphor and an LED having the phosphor mounted on a light emitting surface.

According to the present invention, it is possible to provide a phosphor with improved color rendering and reliability without impairing its high-luminance emission as compared with a YAG phosphor, and a white light emitting device using this phosphor can be provided. Can be provided.

The present invention is a Ce-activated La system having a peak wavelength of 536 nm excited by light of 455 nm, a fluorescence intensity of 150% expressed as a relative value with the peak height of a standard sample (YAG) being 100%, and a half-value width of 111 nm. A phosphor of silicon nitride (A) , a peak wavelength of 544 nm excited with 455 nm light, and a β sialon with a fluorescence intensity of 288% , which is expressed as a relative value with the peak height of the standard sample (YAG) as 100%. It has a certain oxynitride phosphor (B) and a nitride phosphor (C) which is SCASN having a peak wavelength of 620 nm excited by 455 nm light, and the blending ratio of the phosphor (A) is 39 mass% or more and 72 mass% %, The blending ratio of the phosphor (B) is 13.6 mass% or more and 45.0 mass% or less, and the blending ratio of the phosphor (C) is 10.0 mass% or more and 20.0 mass% or less. And Light body (A), a phosphor sum is not less than 88 mass% of (B) and (C).

By mixing these three kinds of phosphors, it was possible to obtain a phosphor with improved color rendering and reliability without impairing its high-luminance emission as compared with YAG phosphors.

The phosphor (A) is a broad phosphor that emits green to yellow, and the phosphor (B) is a sharp phosphor that emits green. Both are highly reliable oxynitride phosphors, and phosphors containing these are also highly reliable. Usually, when phosphors having different hues are blended, the excitation wavelength region and the emission wavelength region overlap each other, so that additivity does not hold, and the emission peak is lower than the synthesized calculated value. In the combination, since the ratio of the light emission of one phosphor used for excitation of the other phosphor is low, it is close to the calculated value. Below this, combining the broad phosphor (A) that covers the yellow region of YAG and the sharp phosphor (B), which has a much higher peak intensity than YAG, to achieve both color rendering and brightness. I can do it. Furthermore, since the phosphors (A) and (B) have few red components, it is necessary to add the phosphor (C). The blending ratio of the phosphor (A) is 39.0% by mass or more and 72.0% by mass or less, and the blending ratio of the phosphor (B) is 13.6% by mass or more and 45.0% by mass or less. The blending ratio of the phosphor (C) is 10.0% by mass or more and 20.0% by mass or less.

The fluorescence intensity of the phosphor is expressed as a relative value in% with the peak height of the standard sample (YAG, specifically, P46Y3 manufactured by Mitsubishi Chemical Corporation) as 100%. The fluorescence intensity measuring instrument is an F-7000 spectrophotometer manufactured by Hitachi High-Tech Co., Ltd., and the measuring method is as follows.
<Measurement method>
1) Sample set: A quartz cell is filled with a measurement sample and a standard sample, and is alternately set in a sufficiently aged measuring machine for measurement. The filling was performed up to about 3/4 of the cell height so that the relative filling density was about 35%.
2) Measurement: Excitation with 455 nm light and reading of the peak height of 400-700 nm. The measurement was performed 5 times, and the average value of the remaining three points was obtained except for the maximum and minimum values.

The peak wavelength of the phosphor is determined as the maximum intensity wavelength when measuring the fluorescence intensity. The half-value width of the phosphor was measured using the LABsphere (registered trademark) Spectralon standard reflector (99%, 2.0 "× 2.0") manufactured by HALMACcompany using the MCPD-7000 instantaneous multi-measurement system manufactured by Otsuka Electronics. Used as a standard sample. The measuring method is that a sample is filled in a central portion φ16 mm of an alumina stone plate to a thickness of 3 mm, lightly pressed with a quartz plate, and then set by grinding. Excitation is performed with light at 455 nm, the peak height of 300 to 800 nm is read to determine the integrated intensity, and the width at half the maximum value is obtained. The measurement was performed five times, and the average value of the remaining three points was obtained except for the maximum and minimum values.

The phosphor (A) in the present invention has a peak wavelength of 536 nm excited by light of 455 nm, a fluorescence intensity of 150% indicating a relative value with the peak height of the standard sample (YAG) being 100%, and a half-value width of 111 nm . It is a nitride phosphor. Specifically, there is Ce-activated La-based silicon nitride, and more specifically, it can be obtained as BY-201A of Mitsubishi Chemical Corporation. This is a phosphor having a light emission peak in the green region, but since it covers a wide range up to the yellow region, high brightness is easily obtained. In addition, since excitation hardly occurs at 544 nm which is the emission peak of the phosphor (B), an efficient combination with the phosphor (B) is possible. Furthermore, since there is a light emission peak slightly shorter than β sialon, good color reproducibility is expressed when combined with a sharp phosphor (B).

The phosphor (B) in the present invention is a green light emitting oxynitride having a peak wavelength of 544 nm excited by 455 nm light and a relative value with the peak height of the standard sample (YAG) as 100% expressed in% as a percentage . It is a phosphor. Specifically, there is β sialon, and more specifically, there is GR-MW540K in Aron Bright (registered trademark) of Denki Kagaku Kogyo Co., Ltd. These β-sialons have high quantum efficiency, which is unprecedented, so that high brightness is easily obtained, and a sharp peak waveform with a half-value width of about 50 to 55 nm is exhibited, so that high color reproducibility is exhibited.

The phosphor (C) in the present invention is a nitride phosphor having a peak wavelength of 620 nm excited by 455 nm light . Specifically, it is a red phosphor abbreviated as SCASN and called Escazun, and more specifically, there is Mitsubishi Chemical Corporation BR-102D . A phosphor mixed with BR-101A (peak wavelength: 650 nm) manufactured by Mitsubishi Chemical Corporation may be used as the phosphor (C) for adjusting the light emitting region within a range not exceeding the amount of these red phosphors added.

In order to maintain high brightness and high reliability, it is better that the amount of the phosphor (A), phosphor (B) and (C) is large, and when the respective blending ratios are a, b and c 88% by mass ≦ a + b + c. In order to obtain higher color reproducibility, the balance can be added with phosphors such as green and red, and high-intensity yellow and orange phosphors. preferable. Further, the ratio of the combination of the phosphors (A) and (B) is preferably in the range of 1 ≦ a / b because the mixed phosphor has a high emission peak intensity, and a // in order to cover the yellow region. A range of b ≦ 4 is preferred. Particularly preferably, 1.2 ≦ a / b ≦ 2.5.

The mixing means with the phosphors (A), (B) and (C) and other phosphors can be appropriately selected as long as it can be uniformly mixed or mixed to a desired mixing degree. In this mixing means, it is premised that impurities are not mixed and the shape and particle size of the phosphor are not clearly changed.

The invention from another viewpoint of the present application is a light emitting device including the above-described phosphor and an LED having the phosphor mounted on a light emitting surface. The phosphor when mounted on the light emitting surface of the LED is sealed by a sealing member. The sealing member includes a resin and glass, and the resin includes a silicone resin. As the LED, it is preferable to appropriately select a red light emitting LED, a blue light emitting LED, or an LED emitting another color in accordance with the color finally emitted. In the case of a blue light emitting LED, the LED is formed of a gallium nitride semiconductor. The peak wavelength is preferably from 440 nm to 460 nm, and more preferably from 445 nm to 455 nm. The size of the light emitting part of the LED is preferably 0.5 mm square or more, and the size of the LED chip can be appropriately selected as long as it has the area of the light emitting part, preferably 1.0 mm × 0.5 mm. More preferably, it is 1.2 mm × 0.6 mm.

  Examples according to the present invention will be described in detail with reference to tables and comparative examples.

The phosphors shown in Table 1 are phosphors (A), (B) and (C) in the phosphor of the present invention, and phosphors of comparative examples thereof. Of the phosphors (A) in Table 1, only P2 is a phosphor having a peak wavelength and fluorescence intensity within the range of claim 1. Of the phosphors (B) in Table 1, only P5 is a phosphor having a peak wavelength and fluorescence intensity within the range of claim 1. Of the phosphors (C) in Table 1, only P7 is a phosphor having a peak wavelength and fluorescence intensity within the range of claim 1.

These phosphors were mixed at a ratio shown in Table 2 to obtain phosphors according to Examples and Comparative Examples.

The phosphor of Example 1 is 39% by mass of the P2 phosphor of Table 1 as the phosphor (A), 39% by mass of the P5 phosphor of Table 1 as the phosphor (B), and the phosphor (C ) Is 20% by mass of the phosphor of P7 in Table 1 and 2% by mass of the phosphor of P3 in Table 1 which is a comparative example of the phosphor (A). The values of P1 to P9 in the structure of the phosphor in Table 1 are mass%. For mixing phosphors, a total of 2.5 g was weighed and mixed in a plastic bag, and then a revolving mixer (stock) with 47.5 g of silicone resin (Toray Dow Corning OE6656) The company was mixed with Shintaro Awatori ARE-310 (registered trademark). In Table 1, a + b + c and a / b indicate the mixing ratio of P2 which is an example of the phosphor (A), a, the mixing ratio of P5 which is the example of the phosphor (B), and the implementation of the phosphor (C). It is a value when the blending ratio of P7 as an example is c. However, c contains P8 and P9, when not exceeding the compounding quantity of P7.

Mounting on the LED was performed by placing the LED on the bottom of the concave package body, wire bonding the electrode on the substrate, and then injecting the mixed phosphor from the microsyringe. After mounting, it was cured at 120 ° C., and post-cured at 110 ° C. for 10 hours for sealing. The LED used had an emission peak wavelength of 448 nm and a chip size of 1.0 mm × 0.5 mm.

The evaluation shown in Table 2 will be described.
As an initial evaluation in Table 2, the evaluation of color rendering was adopted. For the evaluation of color rendering, a color reproduction range was adopted, and the area was expressed as an area (%) of the NTSC standard ratio in color coordinates. The larger the number, the higher the color rendering. The pass condition for evaluation is 70% or more, and it can be said that 72% or more is excellent in color reproducibility, and less than 68% is inferior in color reproducibility. This is a condition that is said to be employed in LED monitors.

The luminance in Table 2 was evaluated by the luminous flux at 25 ° C. The measured value after applying a current of 100 mA for 10 minutes was taken. The pass condition of evaluation is 27.7 lm or more. Since this value varies depending on the measuring machine and conditions, it is a value set as (lower limit value of the example) × 90% for relative comparison with the example.

The high temperature characteristics shown in Table 2 were evaluated based on attenuation with respect to a light beam at 25 ° C. It is a value when the light flux at 50 ° C., 100 ° C., and 150 ° C. is measured and 25 ° C. is taken as 100%. The pass conditions for evaluation are 97% or more at 50 ° C, 95% or more at 100 ° C, and 90% or more at 150 ° C. Although this value is not a standard value common to the world, it is considered as a standard for a highly reliable light-emitting element at present.

The long-term reliability in Table 2 is the attenuation value of the luminous flux when the initial value is set to 100% when the luminous flux is measured after being taken out after leaving at 500 ° C. and 85% RH for 500 and 2,000 hrs and dried at room temperature. .
The pass conditions for the evaluation are 96% or more at 500 hrs and 93% or more at 2,000 hrs. This is a value that cannot be achieved without a highly reliable phosphor.

As shown in Table 2, the examples of the present invention show relatively good color reproducibility and luminous flux values, and the attenuation of luminous flux when stored for a long time under high temperature or high temperature and high humidity is also relatively small.
Comparative Examples 2, 4, 8, 9, and 11 of the present invention are inferior in color reproducibility, and Comparative Examples 1, 3, 5, 6, 7, 10, and 12 have small light flux values. In Comparative Examples 1 to 4 in which the silicate phosphor outside the scope of the present invention is used as the phosphor (A), the LED package is inferior in high temperature characteristics and long-term reliability and has low reliability, such as a television or a monitor. It can hardly be applied to products.

The phosphor of the present invention is used in a white light emitting device. The white light emitting device of the present invention is used for a backlight of a liquid crystal panel, an illumination device, a signal device, and an image display device.

Claims (3)

It is a Ce-activated La-based silicon nitride having a peak wavelength of 536 nm excited by light of 455 nm, a fluorescence intensity of 150% relative to the standard sample (YAG) peak height of 100%, and a half value width of 111 nm. there phosphor and (a), the peak wavelength of 544nm when excited with light of 455 nm, the peak height oxynitride is a fluorescence intensity 288% of β-sialon of displaying a relative value% and 100% of the standard sample (YAG) It has a phosphor (B) and a nitride phosphor (C) which is SCASN having a peak wavelength of 620 nm excited by 455 nm light, and the blending ratio of the phosphor (A) is 39.0 mass% or more and 72.0 mass %, The blending ratio of the phosphor (B) is 13.6 mass% or more and 45.0 mass% or less, and the blending ratio of the phosphor (C) is 10.0 mass% or more and 20.0 mass% or less. And fireflies Body (A), (B) and phosphor total is 88.0 mass% or more (C). The phosphor according to claim 1, which is blended so that 1 ≦ a / b ≦ 4 when the blending ratio a of the phosphor (A) and the blending ratio b of the phosphor (B) are set. The light-emitting device which has the fluorescent substance as described in any one of Claim 1 or 2 , and LED which mounted the said fluorescent substance in the light emission surface.