JP5916413B2 - 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-type sialon and a red light emitting phosphor (see Patent Document 1), and a phosphor in which a red light emitting phosphor having a specific color coordinate and a green light emitting phosphor are combined. Yes (see Patent Document 2).

JP 2007-180483 A JP 2008-166825 A

An object of the present invention is to provide a phosphor having both high luminance and high reliability by adding an oxynitride phosphor to a specific nitride phosphor, and a white color using this phosphor. The object is to provide a light emitting device.

The present invention relates to an oxynitride fluorescence which is a β-sialon phosphor having a peak wavelength of 542 nm excited by light at 455 nm and a fluorescence intensity of 286% , which is expressed as a relative value with the peak height of the standard sample (YAG) as 100%. Nitride fluorescence mainly composed of SCASN having a fluorescence intensity of 177% with a peak value of 620 nm excited by 455 nm light and a relative value with the peak height of the standard sample (YAG) as 100% expressed in% has a body (B), or less 89 parts by mass ratio 74 parts by mass or more of the phosphor (a), below 19 parts by mass ratio 11 parts by mass or more of the phosphor (B), phosphor ( B) is a phosphor in which the blending ratio of the SCASN phosphor contained as the main phase is 11 parts by mass or more and 19 parts by mass or less .

The blending ratio of the phosphors is defined as a + b ≧ when the blending ratio of the oxynitride phosphor (A) which is a β-type sialon phosphor and the nitride phosphor (B) having SCASN as a main phase is a and b It is preferable to have a relationship of 88 parts by mass and 4.0 ≦ a / b ≦ 8.0.

The phosphor (A) is a phosphor having β-sialon and the phosphor (B) is a phosphor having SCASN as a main phase.

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 having high luminance, high temperature characteristics and long-term reliability, and a white light emitting device using the phosphor.

The present invention includes an oxynitride phosphor (A) having a peak wavelength of 540 nm to 545 nm and a fluorescence intensity of 280% to 300%, and a nitride phosphor (B) having a peak wavelength of 615 nm to 625 nm. The phosphor in which the blending ratio of (A) is 74 parts by weight or more and 89 parts by weight or less, and the blending ratio of the phosphor (B) is 11 parts by weight or more and 19 parts by weight or less.

By mixing these two kinds of phosphors, a phosphor having high brightness, high temperature characteristics and long-term reliability could be obtained.

The blending ratio of the phosphor (A) is 74 parts by weight or more and 89 parts by weight or less, and the blending ratio of the phosphor (B) is 11 parts by weight or more and 19 parts by weight or less. If the blending ratio of the phosphor (A) is too small, the luminance tends to be low, and if it is too large, it tends to be difficult to obtain high color rendering, so this range is preferable, and the blending ratio of the phosphor (B) is also high. If the amount is too small, high color rendering properties are not exhibited. If the amount is too high, white light itself cannot be obtained. If the amount is too large, the luminance decreases, and further, white light may not be obtained.

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 phosphor (A) in the present invention is a green light emitting oxynitride phosphor having a peak wavelength of 540 nm to 545 nm and a fluorescence intensity of 280% to 300%. Specifically, there is a β-type sialon, and more specifically, there are GR-MW540J, GR-MW540K, GR-MW540L, etc. of Aron Bright (registered trademark) of Denki Kagaku Kogyo Co., Ltd. These have high quantum efficiencies unprecedented as highly reliable β sialon phosphors, and high brightness is easily obtained.

The phosphor (B) in the present invention is a nitride phosphor having a peak wavelength of 615 nm or more and 625 nm or less. Specifically, it is a red phosphor abbreviated as SCASN and called Escazun, and more specifically, there are Mitsubishi Chemical Corporation BR-102D and Intematix ER6238 (peak wavelength 620 nm). As long as the amount of these red phosphors is not exceeded, Mitsubishi Chemical Corporation BR-102C and BR-102F, Intematix ER6436 (peak wavelength 630 nm) and Intematix ER6535 (peak wavelength 640 nm) are used for adjusting the emission peak. ), ER6634, Mitsubishi Chemical Corporation BR-101A (peak wavelength: 650 nm), etc. may be mixed.

In order to maintain high luminance and high reliability, it is better that the blending amount of the phosphor (A) and the phosphor (B) is large. When the blending ratios are a and b, 88 parts by mass ≦ a + b preferable. 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.

The phosphor (B) has a lower visibility than the phosphor (A) and is inferior in brightness. Therefore, the blending ratio is preferably low. However, when the phosphor (B) is too low, the color rendering property is lowered, which is severe. Since the LED does not show white light, the range of 4.0 ≦ a / b ≦ 8.0 is preferable.

The mixing means for the phosphors (A) and (B), 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), and (C) used in Examples and Comparative Examples of the present invention. 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. Further, P6 and P7 in Table 1 are other phosphors.

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 74% by mass of the phosphor of P2 in Table 1 as the phosphor (A), 11% by mass of the phosphor of P5 in Table 1 as the phosphor (B), and other fluorescence. As a body, 15 mass% of the phosphor of P6 in Table 1 is blended. The values of P1 to P7 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 and a / b are values when the mixing ratio of P2 which is an example of the phosphor (A) is a and the mixing ratio of P5 which is the example of the phosphor (B) is b. Since Comparative Example 4 does not contain P5 of the phosphor (B), it is not a target for a / b. When b does not exceed the blending amount of P5, P6 is included.

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 adopted for general LED-TV.

The luminance in Table 2 was evaluated by the luminous flux at 25 ° C. The measured value after applying a current of 60 mA for 10 minutes was taken. The pass condition of evaluation is 27.5 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 at 85 ° C. and 85% RH at 500 hrs and 2,000 hrs after being taken out 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 (color rendering) and luminous flux values (luminance luminous flux), and attenuation of luminous flux when stored for a long time under high temperature and high temperature and high humidity. Was also relatively small.
Comparative Examples 1, 3, 5, 6, and 7 of the present invention are inferior in color reproducibility. Similarly, Comparative Examples 2, 4, 7, and 8 have small light flux values. In Comparative Examples 1, 2, 3, and 5 using YAG or silicate phosphor outside the scope of the present invention 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 (3)

Peak wavelength 542nm when excited with light of 455 nm, the peak height of 100% and a relative value of the percentage fluorescence intensity 286% of β-sialon phosphor is a oxynitride phosphor of the standard sample (YAG) (A) And a nitride phosphor (B) having a main wavelength of SCASN having a peak wavelength of 620 nm excited by light of 455 nm and a relative value with the peak height of the standard sample (YAG) as 100% expressed in%. the has not more than 89 parts by mass ratio 74 parts by mass or more of the phosphor (a), below 19 parts by mass ratio 11 parts by mass or more of the phosphor (B), mainly phosphor (B) The phosphor whose compounding ratio of the SCASN phosphor contained as a phase is 11 parts by mass or more and 19 parts by mass or less . When the blending ratio of the phosphors according to claim 1 is such that the blending ratios of the phosphors (A) and (B) are a and b, a + b ≧ 88 parts by mass and 4.0 ≦ a / b ≦ 8. A phosphor having a relationship of zero. The light-emitting device which has the fluorescent substance as described in any one of Claims 1 thru | or 2 , and LED which mounts the said fluorescent substance on the light emission surface.