JP2013163733A - Phosphor and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor having high brightness, high temperature characteristics and long-term reliability, and to provide a white light-emitting device using the phosphor.SOLUTION: The phosphor includes an oxynitride phosphor (A) with 530-535 nm peak wavelength and 200-230% fluorescence intensity and an oxynitride phosphor (B) with 585-604 nm peak wavelength and 62% or more external quantum efficiency, where the blend ratios of phosphors (A) and (B) are each 30-50 mass%.

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 of them are required to reduce the decrease in luminance when used under high temperature or for a long 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 provides an oxynitride phosphor (A) having a peak wavelength of 530 nm or more and 535 nm or less, a fluorescence intensity of 200% or more and 230% or less, and an acid having a peak wavelength of 585 nm or more and 604 nm or less, an external quantum efficiency of 62% or more, and a half-value width of 130 nm or more. A phosphor having a nitride phosphor (B) and a blending ratio of the phosphors (A) and (B) of 30% by mass to 50% by mass.

The phosphor may have a relationship of a + b ≧ 80 mass% and b / a ≧ 1 when the blending ratio of the phosphors is set to a and b of the phosphors (A) and (B). More preferably, the phosphor (A) is β sialon, and the phosphor (B) is preferably a phosphor other than β sialon.

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 as compared with a YAG phosphor, and it is possible to provide a white light emitting device using this phosphor.

The present invention provides an oxynitride phosphor (A) having a peak wavelength of 530 nm or more and 535 nm or less, a fluorescence intensity of 200% or more and 230% or less, and an acid having a peak wavelength of 585 nm or more and 604 nm or less, an external quantum efficiency of 62% or more, and a half-value width of 130 nm or more. A phosphor having a nitride phosphor (B) and a blending ratio of the phosphors (A) and (B) of 30% by mass to 50% by mass.

In the present invention, the phosphor (A) having a sharp emission peak in the green region that is insufficient for YAG emission and the broad emission peak on the longer wavelength side than YAG, that is, the red color that is insufficient for YAG simultaneously with the yellow component. This is to create a mixture of phosphors (B) having components, and a phosphor with improved color rendering properties and reliability can be obtained without significantly impairing its high-luminance emission as compared with YAG phosphors. .

The reason why the peak wavelength of the oxynitride phosphor (A) is 530 nm or more and 535 nm or less is to emit green light exhibiting high color rendering properties, and the fluorescence intensity is 200% or more and 230% or less. This is to obtain high brightness. The reason why the peak wavelength of the oxynitride phosphor (B) is 585 nm or more and 604 nm or less and the half-value width is 130 nm or more is to emit light containing both yellow and red components simultaneously, and the external quantum efficiency is 62% or more. The reason is to obtain high luminance. Each of these two types of phosphors has high reliability, and a mixture thereof also has high reliability and exhibits relatively high luminance. Normally, when phosphors with different colors are blended, the excitation wavelength range and emission wavelength range overlap each other, so additiveity does not hold, and the emission peak of the mixture is synthesized with the emission peak of individual phosphors. However, in the combination of the present invention, there is little overlap between the excitation region and the light emission region, and the light emission of one phosphor is hardly used for excitation of the other phosphor, so the decrease in luminance is small. It becomes close to the calculated value. The blending ratio of the phosphor (A) and the phosphor (B) is 30% by mass or more and 50% by mass or less, respectively, in order to obtain white light with high color rendering properties.

In the phosphor of the present invention, a green phosphor having a peak on the shorter wavelength side than the oxynitride (A) or a peak on the longer wavelength side than the oxynitride (B) in order to obtain higher color rendering properties. A red phosphor or the like can be added, but phosphors having an emission peak on the shorter wavelength side than the phosphor (A) are difficult to obtain at present. Silicate phosphors such as BOS are inferior in reliability, and if added in a large amount, the reliability of the entire mixture is impaired. Moreover, since the red phosphor having an emission peak on the longer wavelength side than the phosphor (B) has low visibility, the brightness of the entire mixture is impaired when added in a large amount. When the blending ratios of the phosphors (A) and (B) are a and b, a + b ≧ 80% is preferable. Further, since the phosphor (A) is lower than the phosphor (B) in terms of visibility, it is preferable that b / a ≦ 1 in order to obtain appropriate white light. Eu-activated β sialon has a sharp peak waveform and is therefore a suitable material for the phosphor (A).

The fluorescence intensity of the phosphor is indicated by a relative value, expressed in%, where the peak height of the standard sample (YAG, specifically, P46Y3 manufactured by Mitsubishi Chemical Corporation) is 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: Excited with 455 nm light, the maximum peak height from 300 nm to 800 nm was read. 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 MCPD-7000 instantaneous multi-measurement system manufactured by Otsuka Electronics Co., Ltd., the labsphere (registered trademark) Spectralon standard reflector manufactured by HALMA Company (99%, 2.0 “× 2.0”). Is 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 from 300 nm 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 is an oxynitride phosphor having a peak wavelength of 530 nm to 535 nm and a fluorescence intensity of 200% to 230%. Specifically, there is β sialon, and more specifically, among Aron Bright (registered trademark) of Denki Kagaku Kogyo Co., Ltd., GR-SW530A, GR-SW530B, GR-SW530C, GR-SW531A, GR-SW531B, There are GR-SW531C, GR-SW532A, GR-SW532B, GR-SW532C, GR-SW533A, GR-SW533B, GR-SW533C, and GR-SW533D. These β sialons are unprecedented phosphor materials having a relatively high peak intensity even though the emission peak is in a short wavelength region. When the peak wavelength is in this wavelength range, β sialon has a sharp waveform with a small half width and good color reproducibility.

The phosphor (B) in the present invention is an oxynitride phosphor having a peak wavelength of 585 nm or more and 604 nm or less, an external quantum efficiency of 62% or more, and a half-value width of 130 nm or more. Specifically, there is OR-K among Aronbright (registered trademark) of Electrochemical Co., Ltd. Although this phosphor is an orange phosphor, it has a half-value width of about 130 nm to 140 nm, and is considerably wider than the half-value width of 90 to 110 nm of a YAG-based phosphor. This is a feature not found in conventional phosphors. In the case of a phosphor having a very wide half-value width as described above, it is not appropriate to discuss the height of the emission peak as a measure of luminance, and integrated intensity and external quantum efficiency are employed. In the present invention, the external quantum efficiency is adopted to be 62% or more. The external quantum efficiency of normal OR-K is 63% to 72%, preferably 65% to 72%. In addition, since it contains a lot of yellow to orange components, it has higher visibility than a red-only phosphor, and high brightness is easily obtained. Moreover, high color reproducibility is expressed by combining with the phosphor (A).

The mixing means with the phosphors (A), (B), 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) and (B) 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.

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 contains 30.0% by mass of the phosphor of P2 in Table 1 as the phosphor (A) and 35.0% by mass of the phosphor of P5 in Table 1 as the phosphor (B). Further, for peak adjustment, the phosphor of P1 in Table 1 is 7.0 mass%, the phosphor of P3 is 7.0 mass%, the phosphor of P4 is 6.0 mass%, and the phosphor of P6 is 15. 0% by mass is blended. The values of P1 to P6 in the structure of the phosphor in Table 1 are mass%. When mixing phosphors, a total of 2.5 g was weighed and mixed in a plastic bag, and a rotating and rotating mixer (stock) The company was mixed with Shintaro Awatori ARE-310 (registered trademark). In Table 1, a + b and b / a are values when the blending ratio of P1 which is an example of the phosphor (A) is a and the blending ratio of P6 which is the phosphor (B) example is b. However, b contains P6 and P7, when not exceeding the compounding quantity of P5.

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 adopted for general LED-TVs.

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 28.0 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 luminous flux attenuation is relatively small when stored for a long time under high temperature or high temperature and high humidity.
Comparative Example 1 of the present invention is a so-called pseudo white light emitting device using YAG, which has good luminance, but is inferior in color rendering, and is less reliable than the examples. Comparative Examples 3, 4, 5, 7, 8, and 9 are also inferior in color reproducibility, and Comparative Examples 2, 5, 6, and 8 have small light flux values. In Comparative Examples 2, 3, 4, and 6, the LED package is inferior in high temperature characteristics and long-term reliability and has low reliability, and cannot be expected to be applied to products such as televisions and monitors.

  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 (4)

An oxynitride phosphor (A) having a peak wavelength of 530 nm to 535 nm and a fluorescence intensity of 200% to 230%, and an oxynitride having a peak wavelength of 585 nm to 604 nm, an external quantum efficiency of 62% or more and a half-value width of 130 nm or more A phosphor having a phosphor (B) and a blending ratio of the phosphors (A) and (B) of 30% by mass to 50% by mass. The phosphor having a relationship of a + b ≧ 80 mass% and b / a ≦ 1 when the blending ratio of the phosphors according to claim 1 is such that the blending ratio of the phosphors (A) and (B) is a and b. . The phosphor according to claim 1, wherein the phosphor (A) is β sialon, and the phosphor (B) is a phosphor other than β sialon. The light-emitting device which has the fluorescent substance as described in any one of Claims 1 thru | or 3, and LED which mounted the said fluorescent substance in the light emission surface.