JP2012036265A - Illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance illuminating device which prevents performance decline and degradation while utilizing the characteristics of a nanocrystalline phosphor.SOLUTION: The illuminating device 10 includes a light emitting device 4 emitting primary light and a wavelength conversion unit absorbing a part of the primary light to emit secondary light. The wavelength conversion unit includes a first wavelength conversion unit 6 containing at least the nanocrystalline phosphor and a second wavelength conversion unit 7 containing a rare-earth-activated phosphor or a transition-metal-element-activated phosphor. In the light emitting device 4, the first wavelength conversion unit 6 and the second wavelength conversion unit 7 are closely stacked in order.

Description

  The present invention relates to a lighting device, and is particularly suitable for a lighting device using a phosphor excited by light emitted from a light source.

  As a next-generation lighting device that is expected to have low power consumption, small size, and high brightness, a lighting device comprising a nanocrystalline phosphor and a light source that emits primary light that excites the phosphor has been actively developed. Yes. The use of nanocrystals for the phosphor is expected to improve the light emission efficiency as compared with conventional phosphors. As a feature of the nanocrystal phosphor, the color of light emitted from blue (short wavelength) to red (long wavelength) can be controlled freely by changing the nanocrystal particle size by the quantum size effect. Then, by optimizing the manufacturing conditions, the dispersion of the nanocrystal particle size distribution is eliminated, and the nanocrystal phosphor having a substantially uniform particle size is obtained, so that a narrow emission spectrum can be obtained.

  An example of an illumination device using such a nanocrystalline phosphor is disclosed in Japanese Patent Application Laid-Open No. 2004-71357. FIG. 8 is a schematic side view of the illumination device disclosed in Patent Document 1. As shown in FIG. In this illuminating device, nanocrystals having different particle diameters are used as the phosphors constituting the wavelength conversion unit, and are stacked in the order of the optical paths and the phosphors having the larger particle diameters. Specifically, it is a red phosphor that has a particle size that emits red light and has the largest particle size, and an InN-based nanocrystal that has a particle size that emits green light and has an intermediate particle size. A green phosphor and a blue phosphor, which is an InN-based nanocrystal having the smallest particle diameter and emitting blue light, are laminated to constitute a wavelength conversion unit. In these phosphors, a red phosphor, a green phosphor, and a blue phosphor are laminated in the order closer to the light source.

JP 2004-71357 A

  However, since the illumination device described in Patent Document 1 uses nanocrystals having different particle diameters as a single material as a wavelength converter, the top surface of the blue phosphor layered last is in the atmosphere. It will be exposed. Originally, nanocrystalline phosphors are vulnerable to oxygen and moisture, so that the uppermost layer phosphor may directly touch air and deteriorate. This leads to a decrease in the performance of the lighting device and causes a problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize a long-life lighting device capable of preventing performance degradation and deterioration while utilizing the characteristics of a nanocrystalline phosphor. There is.

  An illumination device according to the present invention includes a light emitting element that emits primary light and a wavelength conversion unit that absorbs part of the primary light and emits secondary light, and the wavelength conversion unit includes at least The light emitting device includes a first wavelength conversion unit including a nanocrystalline phosphor and a second wavelength conversion unit including a rare earth activated phosphor or a transition metal element activated phosphor. The conversion unit and the second wavelength conversion unit are stacked in close proximity to each other.

  In the illumination device according to the present invention, the nanocrystalline phosphor is made of a III-V group compound semiconductor containing In and P or an II-VI compound semiconductor containing Cd and Se.

  The illumination device according to the present invention is characterized in that the nanocrystalline phosphor includes at least one of InP and CdSe.

  In the illumination device according to the present invention, the rare earth activated phosphor includes Ce or Eu as an activator.

  The lighting device according to the present invention is characterized in that the rare earth-activated phosphor is a nitride-based phosphor.

  Moreover, the lighting device according to the present invention is characterized in that the rare earth activated phosphor is a sialon phosphor.

  Moreover, the illuminating device according to the present invention is characterized by laminating in order of phosphors having a long peak wavelength in the order of the optical path of the primary light.

  According to the illuminating device of the present invention, it is possible to realize a long-life illuminating device while making use of the characteristics of the nanocrystalline phosphor while preventing performance degradation and deterioration.

It is sectional drawing of an illuminating device. It is a figure which shows the manufacturing process of an illuminating device. It is a figure which shows the manufacturing process of an illuminating device. It is a figure which shows the emission spectrum of an illuminating device. It is a figure which shows the comparative example with respect to an Example. It is a figure which shows the comparative example with respect to an Example. It is a measurement result of the light emission integrated intensity | strength with the time passage of an illuminating device. It is a block diagram of the conventional illuminating device.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In this specification, “nanocrystal” refers to a crystal in which the crystal size is reduced to about the exciton Bohr radius, and exciton confinement or band gap increase due to the quantum size effect is observed.

<Embodiment 1>
FIG. 1 is a cross-sectional view of the lighting device according to the present embodiment. The illuminating device 10 includes a substrate 2 on which the electrode 1 is formed, a package 3 and a light emitting element 4 provided on the electrode 1, a wire 5 that connects the light emitting element 4 and the electrode 1, and a semiconductor nanostructure in the optical path order of the light emitting element 4. The first wavelength conversion unit 6 containing particles and the second wavelength conversion unit 7 containing Eu-activated β-sialon phosphor are stacked.

  The conductor forming the electrode 1 has a function as a conductive path for electrically connecting the light emitting element 4, and is electrically connected to the light emitting element 4 by a wire 5. As the conductor, for example, a metallized layer containing metal powder such as W, Mo, Cu, or Ag can be used. Since the substrate 2 is required to have a high thermal conductivity and a high total reflectance, a polymer resin in which metal oxide fine particles are dispersed is preferably used in addition to a ceramic material such as alumina or aluminum nitride. It is done.

  The package 3 is made of polyphthalamide or the like having high reflectance and good adhesion to the sealing resin. The light emitting element 4 is used as a light source, and for example, a GaN light emitting diode having a peak wavelength at 450 nm, a ZnO light emitting diode, a diamond light emitting diode, or the like can be used.

  As the first wavelength conversion unit 6, an InP-based nanocrystal can be used. When the particle size of InP is reduced (nanocrystallization), the band gap can be controlled in the range from blue to red by the quantum effect. For example, a red phosphor, which is an InP-based nanocrystal having a red light emitting particle size (620 to 750 nm), mixed in a silicone resin and cured can be used.

  In addition, a red phosphor that is a nanocrystal made of a III-V group compound semiconductor or II-VI compound semiconductor other than InP may be used as the wavelength conversion unit 6. For example, as a nanocrystalline compound semiconductor composed of a II-VI group compound semiconductor or a III-V group compound semiconductor, in a binary system, as a II-VI group compound semiconductor, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbSe, PbS etc. are mentioned. Examples of the III-V group compound semiconductor include GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InAs, and the like.

  In ternary and quaternary systems, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe, CdHgSe , CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTTe, HgZnSeS, HgZnSeTe, HgZnSTe, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, InGaN, GaAlNP , InAlPAs etc. It is.

  And as the 1st wavelength conversion part 6, it is preferable to use the nanocrystal containing In and P or the nanocrystal containing Cd and Se. This is because a nanocrystal containing In and P or a nanocrystal containing Cd and Se can easily produce a nanocrystal having a particle size that emits light in the visible light region (380 nm to 780 nm).

  Among them, it is particularly preferable to use InP or CdSe. The reason is that InP and CdSe are easy to manufacture because there are few constituent materials, and also show high quantum yield, and show high luminous efficiency when irradiated with LED light. The quantum yield here is the ratio of the number of photons emitted as fluorescence to the number of absorbed photons.

  Furthermore, it is preferable to use InP which does not contain Cd which shows strong toxicity as the first wavelength conversion unit 6.

  Further, as the second wavelength conversion unit 7, a rare earth activated phosphor or a transition metal element activated phosphor is suitable. These phosphors are phosphors in which the luminous efficiency of the phosphor is unlikely to decrease due to the influence of oxygen or moisture. For example, the phosphor matrix is made of yttrium, aluminum, garnet (YAG) with cerium (Ce) as an activator. Examples include YAG: Ce introduced.

Further, these phosphors are desirably nitride phosphors activated with rare earth elements or transition metal elements. Nitride-based phosphors have a feature that light emission efficiency is not easily lowered even at high temperatures. As the nitride-based phosphor, for example, a sialon phosphor can be considered, and a phosphor obtained by activating a rare earth element or a transition metal element in β-type sialon (SiAlON) is known. Β-sialon activated Tb, Yb, Ag becomes a phosphor emitting green light of 525 nm to 545 nm. Furthermore, a green phosphor in which Eu ²⁺ is activated on β-type sialon is known. The Eu-activated β-sialon phosphor can be produced by a conventionally known method. Specifically, for example, a metal compound containing an optically active element Eu such as Eu ₂ O ₃ or EuN, an aluminum nitride (AlN) powder, and a silicon nitride powder (Si ₃ N ₄ ) are uniformly mixed, and 1800 to 2000 are mixed. It can be obtained by firing at a temperature of about ℃. The mixing ratio of these raw material powders is appropriately selected in consideration of the composition ratio of the phosphor after firing.

  Next, an example of a method for manufacturing the lighting device 10 will be described below. 2 and 3 are diagrams illustrating a manufacturing process of the lighting device 10. First, as shown in FIG. 2, an LED package including an electrode 1, a substrate 2, a package 3, a light emitting element 4, and a wire 5 is prepared.

  Next, the toluene solution containing the resin and the nanocrystalline red phosphor is mixed so that the weight ratio of resin: nanocrystalline red phosphor = 1000: 4.62. As the red phosphor that is a nanocrystal, an InP crystal was used. As the silicone resin, SCR 1011 manufactured by Shin-Etsu Chemical Co., Ltd. was used. In addition to SCR 1011, any resin can be used as long as it is a resin in which the red phosphor that is a nanocrystal is uniformly dispersed and is transparent and resistant to heat and light. And as shown in FIG. 3, the resin containing the red fluorescent substance which is a nanocrystal was dripped at the said LED package, and the 1st wavelength conversion part 6 was produced by making it harden | cure in predetermined time.

  Next, the resin: Eu-activated β-sialon phosphor is mixed at a weight ratio of 1000: 200. SCR1011 manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin. Other than SCR 1011, any resin can be used as long as it is a resin in which the Eu-activated β-sialon phosphor is uniformly dispersed and is transparent and resistant to heat and light.

  Thereafter, a resin containing Eu-activated β-sialon phosphor is dropped onto the LED package on which the first wavelength conversion unit 6 is formed, and the second wavelength conversion unit 7 is produced by curing in a predetermined time. did. This time, the thickness of the primary light in the optical path direction of the primary light of the first wavelength conversion unit 6 and the second wavelength conversion unit 7 is adjusted to be the same, but the thickness may be set as appropriate according to the desired color balance. . As described above, the illumination device 10 as shown in FIG. 1 is manufactured. The manufacturing method is not limited to the above method as long as the second wavelength conversion unit 7 is formed on the first wavelength conversion unit 6. Further, in the present embodiment, the second wavelength conversion unit 7 is continuously stacked on the first wavelength conversion unit 6, but between the first wavelength conversion unit 6 and the second wavelength conversion unit 7. Layers other than these may be laminated.

  The emission spectrum of the illumination device 10 produced by the above procedure was measured with a spectrophotometer MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.

  FIG. 4 is a graph showing an emission spectrum of the lighting device 10. By using a red phosphor, which is a nanocrystal, an emission spectrum narrower than that of a conventional red phosphor can be obtained, and the NTSC (National Television System Committee) ratio is improved and color reproducibility is improved as compared with the conventional phosphor. It was.

  In addition, in this embodiment, although the manufacturing method of the illuminating device 10 formed only with a 1st wavelength conversion part and a 2nd wavelength conversion part was shown, the wavelength conversion part which consists of another fluorescent substance is laminated | stacked further. May be. Here, the phosphor in each wavelength conversion unit absorbs all light having energy larger than the respective excitation energy, and develops secondary light as fluorescence. Secondary light emitted from a phosphor with high excitation energy (for example, blue) is absorbed by the phosphor with low excitation energy (for example, red), making it difficult to obtain a desired color balance. In such a case, the secondary light emitted from each phosphor is mostly absorbed again by the phosphors emitting other colors by laminating in order of the phosphors having the long peak wavelengths in the order of the optical path of the primary light. The desired color balance can be easily obtained.

<Embodiment 2>
Next, using several kinds of lighting devices 10 manufactured by the above-described methods and materials, the emission intensity and the change with time of the emission intensity were measured. First, the second wavelength conversion unit 7 was laminated on the first wavelength conversion unit 6, and the amount of Eu-activated β-sialon phosphor contained in the silicone resin of the second wavelength conversion unit was changed. Three kinds of things were produced. That is, the amount of Eu-activated β-sialon phosphor contained in 1 g of the silicone resin SCR1011 of the second wavelength conversion unit 7 is (A) 0.03 g, (B) 0.1 g, (C) 0.3 g There are three types.

(Comparative example)
Next, as a comparative example, a lighting device (d) in which only a silicone resin is laminated on the first wavelength conversion unit 6, and no silicone resin is laminated on the first wavelength conversion unit and exposed to the air. The lighting device (e) in the state was prepared. FIG. 5 shows an illumination device 10 a (2) in which a silicone resin 8 is laminated on the first wavelength conversion unit 6. The silicone resin 8 was laminated using the SCR 1011 described above so as to have substantially the same thickness as that of the second wavelength conversion unit shown in FIG. FIG. 6 shows an illumination device 10 b (e) in which nothing is stacked on the first wavelength conversion unit 6. That is, the upper surface of the first wavelength conversion unit 6 is exposed to the air.

(Measurement result)
Accordingly, FIG. 7 shows the results of comparative measurements of the integrated emission intensities immediately after the manufacture of the illumination device and after a lapse of a certain period of time for the illumination devices (A) to (E). In this embodiment, the emission spectrum was measured using a spectrophotometer MCPD-7000, and the emission intensities at wavelengths of 630 nm to 780 nm were integrated. The integrated emission intensity of the red phosphor, which is a nanocrystal at the time of manufacturing each lighting device, was set to 100, and the integrated emission intensity of the red phosphor, which was a nanocrystal, was calculated in the same manner when 30 days had elapsed after the preparation.

  As shown in (a) to (c) of FIG. 7, when Eu-activated β-sialon phosphor is mixed with silicone resin, it is produced based on the integrated emission intensity of the nanocrystal phosphor immediately after production. It can be seen that even after 30 days have elapsed, the light emission integrated intensity can be suppressed by a decrease of about half of the reference value. Further, (e) 0 (no silicone resin is laminated), the luminous intensity is 30.5 a. u. (Arb unit), and the deterioration has progressed considerably over time. In addition, (d) 0 (laminated only with a silicone resin) has a cumulative emission intensity of 32.3 a. u. Therefore, the deterioration of the accumulated light emission intensity is somewhat suppressed as compared with the case where nothing is laminated. This shows that the silicone resin 8 has a function of protecting the red phosphor, which is a nanocrystal, from oxygen and moisture in the air.

  When the change over time is seen, the Eu-activated β-sialon phosphors mixed with the silicone resin 8 and laminated (i) to (iii) are nanocrystals in any amount mixed. The accumulated emission intensity is higher than when only the silicone resin 8 is laminated (d) on the red phosphor or nothing is laminated (e). In particular, (c) a mixture of 0.3 g of Eu-activated β-sialon phosphor per gram of silicone resin has a cumulative emission intensity of 55.5 a. u. And has an excellent anti-deterioration effect. Since the rare earth activated or transition metal element activated phosphor has a property resistant to oxygen and moisture, by laminating it by including it in a resin, the phosphor that is the nanocrystal below it is sealed, The protective function is improved. Furthermore, it has been clarified through experiments that the effect is further enhanced by increasing the concentration of the rare earth activated or transition metal element activated phosphor.

  As described above, when a rare earth activated or transition metal element activated phosphor is used on a nanocrystalline phosphor, the rare earth activated or transition metal element activated phosphor is not a conventional phosphor. Because it has both the function and the function of protecting the nanocrystal phosphor nanocrystal, there is no need to use a special laminated structure or cap such as a resin to protect the nanocrystal phosphor from oxygen and moisture. The manufacturing process does not increase. As described above, according to the present invention, while making use of the characteristics of a phosphor that is a nanocrystal, the phosphor that is a nanocrystal is protected from oxygen and moisture, the deterioration of the illumination device is prevented, and an illumination device having excellent durability is provided. Can be obtained efficiently.

DESCRIPTION OF SYMBOLS 1 Electrode 2 Board | substrate 3 Package 4 Light emitting element 5 Wire 6 1st wavelength conversion part 7 2nd wavelength conversion part 8 Silicone resin 10, 10a, 10b Illuminating device

Claims (7)

A light emitting element that emits primary light;
In a lighting device including a wavelength conversion unit that absorbs part of the primary light and emits secondary light,
The wavelength conversion unit is composed of a first wavelength conversion unit including at least a nanocrystalline phosphor, and a second wavelength conversion unit including a rare earth activated phosphor or a transition metal element activated phosphor,
The lighting device, wherein the light emitting element includes a first wavelength conversion unit and a second wavelength conversion unit stacked in close proximity to each other.   The illumination device according to claim 1, wherein the nanocrystalline phosphor is made of a III-V compound semiconductor containing In and P or a II-VI compound semiconductor containing Cd and Se.   The lighting device according to claim 2, wherein the nanocrystalline phosphor includes at least one of InP and CdSe.   The lighting device according to claim 1, wherein the rare earth activated phosphor includes Ce or Eu as an activator.   The lighting device according to claim 4, wherein the rare earth activated phosphor is a nitride-based phosphor.   The lighting device according to claim 5, wherein the rare earth activated phosphor is a sialon phosphor.   The lighting device according to claim 1, wherein the lighting devices are stacked in the order of phosphors having a long peak wavelength in the order of the optical path of the primary light.