JP2013211340A - Light-emitting device and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device and a luminaire in which chromaticity shift occurrent during high temperature can be suppressed.SOLUTION: A light-emitting device 1 includes a light-emitting element 4 emitting primary light, and a plurality of phosphors 6, 7, 8 excited by the primary light to emit secondary light having a wavelength longer than that of the primary light. The plurality of phosphors include a first phosphor and a second phosphor having temperature quenching larger than that of the first phosphor. When the temperature rises, emission intensity of secondary light emitted from the first phosphor increases, and emission intensity of secondary light emitted from the second phosphor decreases in a wavelength region having complementary color relationship with the primary light.

Description

  The present invention relates to a light emitting device that includes a light emitting element that emits primary light and a wavelength conversion unit that emits secondary light, and an illumination device including the light emitting device.

  Conventionally, as a light-emitting device that realizes white, a light-emitting element is used as a light source, and a YAG-based phosphor of a wavelength conversion unit is excited by light emitted from the light-emitting element, and the emitted fluorescence and the emitted light A light-emitting device that obtains a pseudo white color by mixing the colors is known.

  In addition, active development has also been made on light-emitting devices configured by combining a plurality of phosphors such as a red phosphor and a green phosphor, or a red phosphor, a green phosphor and a blue phosphor in the wavelength converter. The light emitting device is superior in color rendering to the light emitting device that obtains the pseudo white color.

  By the way, in a light emitting device that emits light by exciting a phosphor using a light emitting element, the temperature of the phosphor rises and the emission intensity of the phosphor decreases because the light emitting element becomes hot during operation and generates heat. A phenomenon called temperature quenching occurs. At a high temperature, the light emission intensity from the light emitting element is slightly decreased, but the light emission intensity of the phosphor due to the influence of the temperature quenching is significantly decreased.

  Therefore, for example, in the case of a light emitting device including a red phosphor, a blue phosphor, and a green phosphor in the wavelength conversion unit, the red light emission, the blue light emission, or the green light emission and the light emitting element emitted from each of the above phosphors. There arises a phenomenon called chromaticity deviation in which the balance of the emission color is lost with the emitted light.

  Non-Patent Document 1 discloses the above-described chromaticity shift with respect to the emission intensity of the oxynitride / nitride phosphor and the temperature dependence of the emission spectrum.

FIG. 6 shows a chromaticity shift caused by temperature quenching of a phosphor in a white LED lamp. FIG. 6A shows β-SiAlON: Eu as a green oxynitride phosphor, and yellow oxynitride fluorescence. The temperature dependence of the emission peak intensity of Ca-α-SiAlON: Eu as the body, CaAlSiN ₃ : Eu as the red nitride phosphor, and (Y, Gd) ₃ Al ₅ O ₁₂ : Ce as the yellow oxide phosphor is shown. Yes. The excitation wavelength is 460 nm only for (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, and 450 nm for the other phosphors. The SiAlON described above is synonymous with the sialon described in detail below.

As can be seen from FIG. 6A, at a high temperature, the emission intensity of (Y, Gd) ₃ Al ₅ O ₁₂ : Ce is particularly large compared to oxynitrides and nitride phosphors.

Further, FIG. 6B shows from the left toward the paper surface, β-SiAlON: Eu as a green oxynitride phosphor, Ca-α-SiAlON: Eu as a yellow oxynitride phosphor, and a red nitride phosphor. The emission spectrum of each phosphor of CaAlSiN ₃ : Eu is shown, and it can be seen that the emission intensity decreases with increasing temperature.

  As described above, it can be understood from the description of Non-Patent Document 1 that the emission intensity of each phosphor decreases at high temperatures, and the degree of decrease in emission intensity varies depending on the chemical composition of the phosphor.

Takeshi Sakuma, “Applications to sialon phosphors and light emitting devices”, [online], [searched on November 7, 2011], Internet <URL: http://repository.dl.itc.u-tokyo.ac .jp / dspace / bitstream / 2261/15750/1 / KSakuma16965.pdf>

  As described above, Non-Patent Document 1 discloses that the emission intensity of each phosphor such as oxynitride and nitride phosphor decreases with temperature quenching. Further, although it has been mentioned that white LED lamps equipped with the phosphor in the wavelength conversion section cause chromaticity deviation at high temperatures, a specific method for eliminating the chromaticity deviation is still a problem. there were.

  Therefore, the present invention has been made to solve the problem, and an object of the present invention is to provide a light emitting device and a lighting device that can suppress chromaticity deviation occurring at a high temperature.

  A light-emitting device according to the present invention is a light-emitting device that includes a light-emitting element that emits primary light, and a plurality of phosphors that are excited by the primary light and emit secondary light having a wavelength longer than that of the primary light. The body includes a first phosphor and a second phosphor whose temperature quenching is larger than that of the first phosphor, and in the wavelength region of light complementary to the primary light as the temperature rises, The emission intensity of the secondary light emitted from the first phosphor increases, and the emission intensity of the secondary light emitted from the second phosphor decreases.

  The peak wavelength of the light emitting element that emits the primary light is 440 nm to 470 nm. More preferably, the light emitting element that emits the primary light has a peak wavelength of 450 nm to 465 nm.

  The first phosphor includes at least one of a green phosphor and a red phosphor. Alternatively, the second phosphor is a yellow-green phosphor or a yellow phosphor.

  The emission peak wavelength of the green phosphor shifts to the longer wavelength side with increasing temperature, and the emission peak wavelength of the red phosphor shifts to the shorter wavelength side with increasing temperature. .

  The green phosphor has an emission spectrum peak wavelength of 520 nm to 550 nm. Alternatively, a peak wavelength of an emission spectrum of the red phosphor is 600 nm to 670 nm.

  The green phosphor is a divalent Eu-activated oxynitride phosphor which is β-sialon. The red phosphor is a divalent Eu-activated nitride phosphor or a divalent Eu-activated oxynitride phosphor that is α-sialon. The yellow-green phosphor is an alkaline earth metal orthosilicate phosphor activated with divalent Eu, and the yellow phosphor is a phosphor having a garnet structure activated with Ce. It is characterized by that.

  A lighting device comprising: a light emitting element that emits primary light; and a plurality of light emitting devices that include a phosphor that is excited by the primary light and emits secondary light having a wavelength longer than that of the primary light in a wavelength conversion unit. In the light emitting device, a phosphor that emits secondary light is included in the wavelength conversion unit so that the light emission intensity of light having a complementary color relationship with the primary light increases as the temperature rises. A first light emitting device that emits light so that the light emission intensity of the light having a complementary color relationship increases, and the secondary light so that the light emission intensity of the light complementary to the primary light decreases with increasing temperature. And a second light-emitting device that emits light so that the light emission intensity of the light complementary to the primary light is reduced by including a phosphor that emits light in the wavelength conversion unit. Light-emitting devices are arranged in a line or plane It is characterized in.

  The light emitting device and the lighting device according to the present invention can suppress the chromaticity shift that occurs at a high temperature.

1 is a cross-sectional view schematically showing a configuration of a light emitting device according to Embodiment 1 of the present invention. Explanatory drawing which shows the emission spectrum of the light-emitting device which concerns on Embodiment 1 of this invention. Explanatory drawing which shows the chromaticity change of the light-emitting device which concerns on Embodiment 1 of this invention. Sectional drawing which shows the structure of an illuminating device typically. Explanatory drawing which shows the chromaticity change which concerns on Example 1 and Comparative Example 1. FIG. Explanatory drawing regarding a prior art.

  The present inventors have found that by combining a plurality of phosphors, a light-emitting device and a lighting device that are less affected by chromaticity deviation can be obtained even at high temperatures.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing the configuration of the light emitting device 1. The frame 2, the reflecting surface 3, the light emitting element 4, the sealing material 5, the red phosphor 6, and the green phosphor. It comprises a body 7, a yellow-green phosphor 8, bonding wires 9 and 10, and lead frames 11 and 12.

  The light-emitting element 4 is an LED element, and is formed by epitaxially growing a GaN-based semiconductor layer on a semiconductor substrate such as sapphire, GaN, or SiC using an MOCVD method or the like. The peak wavelength of the emission spectrum of the light-emitting element is preferably in the range of 440 nm to 470 nm from the viewpoint of increasing the light emission efficiency, and more preferably in the range of 450 nm to 465 nm from the viewpoint of increasing the color rendering properties. .

  The peak wavelength of the emission spectrum of the light emitting element is not limited to the above, and may be 405 nm.

  The frame 2 is provided with a reflective surface 3, and the reflective surface 3 is formed in a mortar shape. The space formed by the reflective surface 3 is provided with the light emitting element 4 at the bottom, filled with a sealing material that becomes transparent after solidification, and the light emitting element 4 is fixed by the sealing material 5. .

  The light emitting element 4 is connected to the lead frame 11 on the bottom surface of the reflecting surface 3 by a conductive adhesive (not shown), and the light emitting element 4 has an n-electrode and a p-electrode (see FIG. (Not shown) and the lead frames 11 and 12 are connected by bonding wires 9 and 10 formed of a gold wire or the like.

  The sealing material 5 is made of, for example, silicon resin, epoxy resin, or the like, and a red phosphor 6, a green phosphor 7, and a yellow green phosphor 8, which will be described later, are dispersed and mixed. The conversion unit 13 is configured.

The red phosphor 6 is a divalent Eu-activated nitride phosphor, and any one can be used as long as the effects of the present invention are not significantly impaired. Specifically, CaAlSiN ₃ : Eu, (Sr, Ca) AlSiN ₃ : Eu, or the like can be used. The peak wavelength of the emission spectrum of the red phosphor 6 is preferably in the range of 600 nm to 670 nm.

  Further, the particle diameter of the red phosphor 6 described above is not particularly limited, but is preferably in the range of 3 to 10 μm, and more preferably in the range of 4 to 7 μm. When the particle size of the red light emitting phosphor 6 is less than 3 μm, the growth as a phosphor crystal is insufficient, and the brightness tends to be greatly reduced. On the other hand, when a particle having a particle size exceeding 10 μm is prepared, abnormally grown coarse particles are likely to be generated, which is not practical.

Further, as the other red phosphor 6, a divalent Eu-activated oxynitride phosphor which is an α-sialon may be used. Specifically, a phosphor represented by a composition of Cax (Si, Al) ₁₂ (O, N) ₁₆ : Eu can be used. The particle size is not particularly limited and is preferably in the range of 2 to 8 μm, and more preferably in the range of 3 to 6 μm. If the particle size is less than 2 μm, crystal growth is insufficient and the brightness tends to decrease greatly. On the other hand, when the thickness exceeds 8 μm, abnormally grown coarse particles are likely to be generated, which tends to be impractical.

Any green phosphor can be used as long as the effects of the present invention are not significantly impaired. For example, a divalent Eu-activated oxynitride phosphor which is a β-sialon is used. Can do. Specifically, the green phosphor 7 is represented by a composition of (Si, Al) ₆ (O, N) ₈ : Eu. The peak wavelength of the emission spectrum of the green phosphor 7 is preferably in the range of 520 nm to 550 nm.

  Further, the particle size of the green phosphor 7 is not particularly limited, but is preferably in the range of 2 to 8 μm, and more preferably in the range of 3 to 6 μm. If the particle size is less than 2 μm, crystal growth is insufficient and the brightness tends to decrease greatly. On the other hand, when it exceeds 8 μm, abnormally grown coarse particles are easily generated, which is not practical.

Further, as the yellow-green phosphor 8, for example, an alkaline earth metal silicate phosphor can be used. Specifically, the yellow-green phosphor 8 is represented by a composition of (Ba, Sr) ₂ SiO ₄ : Eu. As other phosphors, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce or (Lu, Y) ₃ Al ₅ O ₁₂ : Ce having a garnet structure activated with Ce is used. Can do.

  Here, the principle that the influence of the chromaticity deviation can be suppressed even at a high temperature found by the present inventors will be described. FIG. 2 is an emission spectrum relating to light emission emitted from the light emitting device including the yellow-green phosphor 8 and the light emitting device including the red phosphor 6 and the green phosphor 7 in the wavelength conversion unit. It shows the emission intensity that changes with the temperature rise.

  FIG. 2A shows a green phosphor 7 having a green phosphor 7 having an emission peak wavelength in the vicinity of 540 nm and a red phosphor 6 having an emission peak wavelength in the vicinity of 640 nm in a wavelength conversion unit. Is a light emission spectrum of a light emitting device manufactured using a blue LED element having a light emission peak wavelength at 460 nm, the vertical axis is emission intensity, the horizontal axis is wavelength, and corresponds to each temperature from 0 to 100 ° C. 5 emission spectra are shown. What can be seen from the emission spectrum of FIG. 2A is that the emission intensity of the emission spectrum particularly in the vicinity of a wavelength of 590 nm increases as the temperature rises.

  On the other hand, in FIG. 2B, a yellow-green phosphor 8 having an emission peak wavelength near 560 nm is provided in the wavelength conversion unit, and a blue LED element having an emission peak wavelength at 460 nm is used as the light emitting element. It is the emission spectrum which concerns on a light-emitting device. As can be seen from the emission spectrum of FIG. 2B, it can be seen that the emission intensity at the emission peak wavelength of the yellow-green phosphor 8 decreases with increasing temperature. This is mainly due to the temperature quenching of the phosphor described above.

  Usually, mainly due to the effect of temperature quenching, as shown in FIG. 2B, the emission intensity of the phosphor decreases as the temperature rises. However, the green phosphor 7 and the red phosphor 6 shown in FIG. 2A are less affected by a decrease in emission intensity due to low temperature quenching, and the emission peak of the red phosphor 6 with increasing temperature. The main reason is that the wavelength shifts to the short wavelength side and the emission peak wavelength of the green phosphor 7 shifts to the long wavelength side as the temperature rises. It is considered that the emission intensity corresponding to approximately yellow light in the vicinity has increased.

  FIG. 3 shows chromaticity changes using chromaticity coordinates. FIGS. 3A and 3B correspond to the light emitting devices of FIGS. 2A and 2B described above as emission spectra. doing.

  From the chromaticity coordinates in FIG. 3A, it can be seen that the color shifts to the red side as the temperature rises. Moreover, it can be seen from the chromaticity change in FIG. 3B that the color shifts to the blue side as the temperature rises.

  As described above, in a light emitting device configured by dispersing a predetermined green phosphor and red phosphor in a wavelength conversion unit and configured by a blue LED element, light that is complementary to the primary light emitted mainly by the blue LED element at a high temperature. It can be seen that the emission spectrum intensity increases.

Therefore, in addition to the green phosphor and the red phosphor, green phosphors having a relatively large influence of temperature quenching are mixed at a predetermined blending ratio to form a light emitting device, which occurs with an increase in temperature. The chromaticity shift of the light emitting device can be suppressed.
In the present embodiment, the light emitting device includes the above-described three types of phosphors of the red phosphor 6, the green phosphor 7, and the yellow-green phosphor 8 in the wavelength conversion unit, but is not limited thereto. . That is, as the temperature rises, a wavelength conversion unit is formed by combining a phosphor that increases the emission intensity of light that is complementary to the light emitted by the blue LED element and a phosphor that has a greater temperature quenching effect than the phosphor. What is necessary is just to comprise. For example, a light-emitting device that includes two types of phosphors, that is, a red phosphor 6 or a green phosphor 7 and a yellow-green phosphor 8 in a wavelength conversion unit can be given.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. The same components are denoted by the same reference numerals, and description thereof is omitted. FIG. 4 is a schematic cross-sectional view of an illuminating device in which light emitting devices are arranged in a plane. 14 is an illuminating device, 15 is a substrate, and 16 and 17 are light emitting devices. The substrate 15 is a printed circuit board on which a conductor layer (not shown) is printed. A laminated substrate obtained by laminating a substrate having a conductor layer formed on the surface of a ceramic substrate, a substrate in which a conductor layer is printed on a single insulating substrate, or the like may be used.

  Each light emitting element 4 is electrically connected to the conductor layer by lead frames 11 and 12. In the light emitting device 16, as the wavelength conversion unit 18, the red phosphor 6 and the green phosphor 7 are dispersed and mixed in the sealing material 5. In addition, the light emitting device 17 is configured by mixing only the yellow-green phosphor 8 into the sealing material 5 as the wavelength conversion unit 19.

  As described above, by arranging the light emitting devices 16 and 17 to be the lighting device 14, the chromaticity shift can be suppressed even when the light emitted by the lighting device 14 is at a high temperature.

<Example 1>
A blue LED element having a peak wavelength at 453 nm was used as the light emitting element. The wavelength conversion unit includes 22 mg of (Sr, Ca) AlSiN ₃ : Eu as a red phosphor, 70 mg of (Si, Al) ₆ (O, N) ₈ : Eu as a green phosphor and a green phosphor. A material containing 30 mg of (Ba, Sr) ₂ SiO ₄ : Eu was used. As a weight ratio, a mixture of 1: 0.43: 0.31 was dispersed in an epoxy resin to produce a light emitting device of Example 1.

<Comparative Example 1>
A light-emitting device was produced in the same manner as in Example 1 except that a wavelength conversion unit containing 100 mg of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce as a yellow phosphor was used.

  The results for Example 1 and Comparative Example 1 are shown in FIG. FIG. 5 shows light emission of the light-emitting device when the temperature is changed from −40 ° C. to 100 ° C. using the xy coordinates, and FIG. 5 (a) relates to the light-emitting device manufactured in Example 1. FIG. 5B relates to the light-emitting device manufactured in Comparative Example 1.

  5A, (x, y) = (0.2491, 0.1966) at −40 ° C. and (x, y) = (0.2432, 0.1922) at 100 ° C. In FIG. The rate of change of x from −40 ° C. to 100 ° C. is approximately 2.37%, and the rate of change of the y value is approximately 2.24%.

  On the other hand, in FIG. 5B, (x, y) = (0.2428, 0.1921) at −40 ° C. and (x, y) = (0.2322, 0.1788) at 100 ° C. The rate of change of x is approximately 4.37%, and the rate of change of y is approximately 6.92%.

  As described above, the light emission of the light-emitting device manufactured in Example 1 illustrated in FIG. 5A is smaller in chromaticity change even when the temperature is higher than the light emission of the light-emitting device illustrated in FIG. It can be seen that the chromaticity deviation occurring at high temperatures can be suppressed.

  As described above, according to the present specification, the phosphor that increases the emission intensity of light that is complementary to the light emitted from the blue LED element is combined with the phosphor that has a higher temperature quenching than the phosphor. By configuring the wavelength conversion unit, it is possible to provide a light emitting device that can suppress chromaticity deviation even at high temperatures.

  In addition, a light emitting device that includes a phosphor that increases the light emission intensity of light complementary to the light emitted from the blue LED element in the wavelength conversion unit, and a light emitting device that includes a phosphor that has a temperature quenching greater than that of the phosphor in the wavelength conversion unit. By arranging them in a row, it is also possible to provide an illumination device that can suppress chromaticity deviation.

1, 16, 17 Light-emitting device 2 Frame 3 Reflecting surface 4 Light-emitting element 5 Sealing material 6 Red phosphor 7 Green phosphor 8 Yellow-green phosphor 9, 10 Bonding wire 11, 12 Lead frame 13, 18, 19 Wavelength converter

Claims (12)

A light emitting element that emits primary light;
A light emitting device comprising a plurality of phosphors that are excited by the primary light and emit secondary light having a longer wavelength than the primary light,
The plurality of phosphors include a first phosphor and a second phosphor having a temperature quenching larger than that of the first phosphor,
As the temperature rises, the emission intensity of the secondary light emitted from the first phosphor increases in the wavelength region of light complementary to the primary light, and the secondary light emitted from the second phosphor increases. A light emitting device characterized in that emission intensity decreases.   The light emitting device according to claim 1, wherein a peak wavelength of the light emitting element that emits the primary light is 440 nm to 470 nm.   The light emitting device according to claim 1, wherein a peak wavelength of the light emitting element that emits the primary light is 450 nm to 465 nm.   The light emitting device according to claim 1, wherein the first phosphor includes at least one of a green phosphor and a red phosphor.   The light emitting device according to claim 1, wherein the second phosphor is a yellow-green phosphor or a yellow phosphor.   The emission peak wavelength of the green phosphor shifts to the longer wavelength side with increasing temperature, and the emission peak wavelength of the red phosphor shifts to the shorter wavelength side with increasing temperature. The light emitting device according to claim 4.   The light emitting device according to claim 4 or 6, wherein a peak wavelength of an emission spectrum of the green phosphor is 520 nm to 550 nm.   The light emitting device according to claim 4 or 6, wherein a peak wavelength of an emission spectrum of the red phosphor is 600 nm to 670 nm.   The light emitting device according to claim 4, wherein the green phosphor is a divalent Eu-activated oxynitride phosphor that is β-sialon.   9. The light emitting device according to claim 4, wherein the red phosphor is a divalent Eu-activated nitride phosphor or a divalent Eu-activated oxynitride phosphor that is α-sialon. apparatus.   The yellow-green phosphor is an alkaline earth metal orthosilicate phosphor activated with divalent Eu, and the yellow phosphor is a phosphor having a garnet structure activated with Ce. The light-emitting device according to claim 5. A light emitting element that emits primary light;
A lighting device comprising a plurality of light emitting devices provided in a wavelength converter with a phosphor that emits secondary light having a wavelength longer than that of the primary light that is excited by the primary light,
The plurality of light emitting devices are:
The phosphor that emits the secondary light is included in the wavelength conversion unit so that the emission intensity of the light that is complementary to the primary light increases as the temperature rises, so that the light that is complementary to the primary light is included. A first light-emitting device that emits light so that the light emission intensity increases;
The phosphor that emits the secondary light is included in the wavelength conversion unit so that the light emission intensity of the light complementary to the primary light decreases as the temperature rises, so that the light complementary to the primary light is included. A second light emitting device that emits light so that the emission intensity of
The lighting device, wherein the first and second light emitting devices are arranged in a line or a plane.