JP5901987B2 - 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. Moreover, both are required to reduce the 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 relates to an oxynitride phosphor (A) which is a β sialon having a peak wavelength of 552 nm and a fluorescence intensity of 256% excited by 455 nm light, and an α sialon having a peak wavelength of 595 nm and a fluorescence intensity of 205% excited by 455 nm light. An oxynitride phosphor (B), a nitride phosphor (C) whose main phase is S-CASN having a peak wavelength of 620 nm excited by light of 455 nm , and a peak wavelength of 537 nm excited by light of 455 nm And an oxynitride phosphor (D) which is β sialon having a fluorescence intensity of 254% , and the total of phosphor (A) and phosphor (B) is 30% by mass to 60% by mass, phosphor (C) Is 10 mass% or more and 17.5 mass% or less, phosphor (D) is 3.0 or more and 6.0 or less by mass ratio of phosphor (C), and phosphor (A) is phosphor (M) by mass ratio. A) of 2.0 or more and 6.0 or less This is a phosphor.

The phosphor sialon phosphor (A) and (D) is beta, phosphor (B) is α-sialon phosphor (C) is a phosphor as a main phase an S-CASN.

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 relates to an oxynitride phosphor (A) which is a β sialon having a peak wavelength of 552 nm and a fluorescence intensity of 256% excited by 455 nm light, and an α sialon having a peak wavelength of 595 nm and a fluorescence intensity of 205% excited by 455 nm light. An oxynitride phosphor (B), a nitride phosphor (C) whose main phase is S-CASN having a peak wavelength of 620 nm excited by light of 455 nm , and a peak wavelength of 537 nm excited by light of 455 nm And an oxynitride phosphor (D) which is β sialon having a fluorescence intensity of 254% , and the total of phosphor (A) and phosphor (B) is 30% by mass to 60% by mass, phosphor (C) Is 10 mass% or more and 17.5 mass% or less, phosphor (D) is 3.0 or more and 6.0 or less by mass ratio of phosphor (C), and phosphor (A) is phosphor (M) by mass ratio. A) of 2.0 or more and 6.0 or less This is a phosphor.

In the present invention, a phosphor mixture similar to the peak waveform of YAG is prepared by blending the phosphor (A) and the phosphor (B), and a specific red phosphor (C) and a green color are produced for this phosphor mixture. By adding the phosphor (D), it was possible to obtain a phosphor with improved color rendering and reliability without impairing its high-luminance emission as compared with the YAG phosphor.

The reason why the peak wavelength excited by 455 nm light of the oxynitride phosphor (A) is 552 nm is to emit light in the range from green to yellow, and the fluorescence intensity is 256%. This is to obtain luminance. The reason why the peak wavelength of the oxynitride phosphor (B) excited by 455 nm light is 595 nm is to emit orange light, and the reason why the fluorescence intensity is 205% is to obtain high luminance. The mixture of these two types of phosphors has high reliability as well. Normally, when phosphors with different hues are blended, the excitation wavelength region and the emission wavelength region overlap each other, so additivity does not hold, and the emission peak is based on the calculated value obtained by combining the emission peaks of individual phosphors. However, in the combination of the present invention, since the ratio of the light emission of one phosphor is used to excite the other phosphor, the calculated value is almost calculated, and the fluorescence is sharper than YAG and has a much higher peak intensity. The peak intensity itself was equal to or higher than that of the YAG phosphor.
The reason why the total of the phosphor (A) and the phosphor (B) is 30% by mass or more and 60% by mass or less is to obtain high color rendering while maintaining high luminance.
The reason why the phosphor (A) is 2.0 or more and 6.0 or less of the phosphor (B) by mass ratio is to obtain a peak waveform similar to YAG.
The reason for limiting the fluorescence intensity of both phosphors is to obtain high brightness.

The reason why the peak wavelength of S-CASN, which is the main phase of the nitride phosphor (C) , excited with 455 nm light is 620 nm is to emit high-luminance red, and the oxynitride phosphor (D) The reason why the peak wavelength excited by 455 nm of light is 537 nm is to emit green with high color rendering properties.
The reason for limiting the fluorescence intensity of the phosphor (D) is to obtain high luminance.
The nitride phosphor (C) is 10% by mass or more and 17.5% by mass or less because when 10% by mass or more, the effect of improving the color rendering properties is exhibited, and when too much, the luminance and color rendering properties are deteriorated. This is because there is no white light.
When the blending ratio of the phosphor (D) is small, the color rendering property tends to be lowered. When the blending ratio is large, the luminance tends to be lowered. Therefore, the mass ratio with respect to the phosphor (C) is 3.0 to 6.0. is there.

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 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 is a green light-emitting oxynitride phosphor having a peak wavelength of 552 nm excited with 455 nm light and a fluorescence intensity of 256% . Specifically, there is β sialon, and more specifically, there is GR-LW552F in Aron Bright (registered trademark) of Denki Kagaku Kogyo Co., Ltd. This β sialon is an unprecedented phosphor material compatible with having a high peak intensity even though the peak wavelength is in the long wavelength region. In β sialon, when the peak wavelength is in this wavelength range, the visibility is higher than that of a normal green phosphor, so that it becomes brighter, while the decrease in color reproducibility is relatively small.

The phosphor (B) in the present invention is an oxynitride phosphor having a peak wavelength of 595 nm excited by light at 455 nm . Specifically, there is α sialon, and more specifically, YL-595A is available from Denki Kagaku Kogyo Co., Ltd. Aron Bright (registered trademark). This is an orange phosphor, which has a higher visibility than a red phosphor and is sharper and has a higher peak intensity than a commonly used red nitride phosphor, so that high brightness is easily obtained. In addition, since the half-value width is slightly wider than β sialon, it contains a red component and exhibits a relatively high color reproducibility when combined with the phosphor (A).

The main phase of 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 that is abbreviated as S - CASN and is called Escazun, and more specifically, there is Mitsubishi Chemical Corporation BR-102D (peak wavelength: 620 nm). In the range not exceeding the addition amount of this red phosphor, for the adjustment of the peak wavelength, Intematix R6436 (peak wavelength 630 nm), R6535 (peak wavelength 640 nm), Mitsubishi Chemical Corporation BR-102C, BR-102F (peak) A phosphor in which a wavelength of 630 nm) or BR-101A (peak wavelength of 650 nm) is mixed may be used as the phosphor (C).

The phosphor (D) in the present invention is an oxynitride phosphor having a peak wavelength of 537 nm excited by 455 nm light and a fluorescence intensity of 254% , specifically β-sialon, more specifically, Among Aron Bright (registered trademark) of Chemical Industry Co., Ltd., there is GR-SW535F . This β sialon is an unprecedented phosphor material that has both a short peak wavelength and a high peak intensity.

In order to maintain high luminance and high reliability, it is better that the amount of phosphor (A), phosphor (B), phosphor (C) and (D) is large, but particularly high color rendering properties are required. When it is necessary to further increase the brightness of the application, when the total amount of the phosphors of the present invention is 100 parts by weight, other phosphors can be added in an amount not exceeding 15 parts by weight. In this case, a highly reliable phosphor blend is preferable.

The mixing means with the phosphors (A), (B), (C), (D), and other phosphors can be appropriately selected as long as they 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), (C) and (D) 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. Of the phosphors (D) in Table 1, only P11 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 20.0% by mass of the phosphor of P2 in Table 1 as the phosphor (A), 10.0% by mass of the phosphor of P5 in Table 1 as the phosphor (B), The phosphor of P7 in Table 1 is 10.0% by mass as the phosphor (C), and 60.0% by mass of the phosphor of P11 in Table 1 is blended as the phosphor (D). The values of P1 to P13 in the phosphor structure 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 and a / b 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 28.6 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, 9, 10, 1112, 112 are also inferior in color reproducibility, and in Comparative Examples 3, 5, 6, 7, 8, 9, 10, 11, 13, 14 Is small. Further, in Comparative Examples 2, 3, 4, and 5 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. It cannot be expected to be applied to products such as TVs 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 (2)

An oxynitride phosphor (A) which is a β sialon having a peak wavelength of 552 nm and a fluorescence intensity of 256% excited by 455 nm light, and an oxynitride which is an α sialon having a peak wavelength of 595 nm and a fluorescence intensity of 205% excited by 455 nm light. Phosphor (B), nitride phosphor (C) having S-CASN having a peak wavelength of 620 nm excited by light at 455 nm as a main phase, peak wavelength 537 nm excited by light at 455 nm , fluorescence intensity 254% The oxynitride phosphor (D), which is a β sialon, has a total of phosphor (A) and phosphor (B) of 30% by mass to 60% by mass and phosphor (C) of 10% by mass or more. 17.5% by mass or less, the phosphor (D) is 3.0 to 6.0 in terms of the mass ratio of the phosphor (C), and the phosphor (A) is 2. Phosphors having a value of 0 to 6.0 The light-emitting device which has the fluorescent substance of Claim 1, and LED which mounted the said fluorescent substance in the light emission surface.