JP5889646B2 - Phosphor plate, light emitting device using phosphor plate, and method of manufacturing phosphor plate - Google Patents

Description

  The present invention relates to a light-emitting device used for illumination or a display, and more particularly to a phosphor plate including a phosphor excited by light output from a light source, a light-emitting device using the phosphor plate, and a method for manufacturing the phosphor plate. It is.

  In recent years, attention has been focused on LED backlights and LED bulbs of liquid crystal displays as light emitting devices using light emitting diodes (hereinafter referred to as LEDs). LEDs have excellent characteristics such as low power consumption, long product life, and small influence on the environment. The light emitting part of the LED backlight or the LED bulb emits a combination of light obtained by wavelength-converting part of the LED light and light not wavelength-converted by the LED phosphor. Various light different from light can be emitted. Such a light-emitting device is highly expected as a light-emitting device that replaces the conventional lighting and backlights of displays, and various developments have been made.

  In general, when a light emitting device is composed of an LED chip and a phosphor, the first method is to cover the LED chip by mixing the phosphor with a resin material, and the second method is to apply the phosphor on the light emitting surface of the LED chip. As a third method, there are various methods such as a method of placing a phosphor-containing sheet on a chip. The most commonly used method is the first method. However, in the case of the first method and the second method, since the sealing resin has a large thickness, light from the LED element is absorbed by the sealing resin, causing light loss, or heat generated by the light emission of the LED is fluorescent. Since it directly affects the body, depending on the type of phosphor, there is a possibility that the wavelength conversion efficiency or the light emission efficiency may deteriorate due to deterioration due to heat.

  For this reason, the phosphor is mixed with a resin, which is the third method, and the resin is solidified separately from the light emitting device, and is fluorescent with inorganic glass or organic glass. A method of using a phosphor plate sandwiching a phosphor or a resin containing a phosphor has attracted attention.

FIG. 6 is a cross-sectional view showing the light emitting device disclosed in Patent Document 1. As shown in FIG. In FIG. 6, a light emitting device 600 includes an element housing package 601, an inert gas 603 such as Ar or N ₂ filled in the package 601 and sealing the LED element 602, and light extraction of the LED element 602. It is comprised from the fluorescent substance board 604 arrange | positioned so that the inert gas 603 may be covered by the side. The phosphor plate 604 includes bubbles as a light traveling direction changing portion that functions in the same manner as the phosphor and the scattering material in a base member such as silicone.

  According to such a method, the light extraction efficiency can be increased, high-intensity irradiation light can be obtained over a long period, and color unevenness can be improved.

JP 2007-123438 A (published on May 17, 2007)

  However, in the light emitting device 600 disclosed in Patent Document 1, since phosphors and bubbles are irregularly dispersed throughout the phosphor plate 604, when the position of a certain phosphor is used as a reference, the phosphor There may be many bubbles on the light exit surface side of the plate. In this case, in the conventional light emitting device 600, the light emitted from the phosphor and traveling toward the light exit surface side of the phosphor plate is scattered backward by the scattering material and returned to the primary light incident surface side of the phosphor plate. As a result, there is a problem that the light extraction efficiency is lowered.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a phosphor plate that improves the extraction efficiency of light emitted by the phosphor, a light emitting device including the phosphor plate, and a method for manufacturing the phosphor plate. It is to provide.

The phosphor plate according to the present invention is a phosphor plate made of a base material, a phosphor, and a scattering material, and the phosphor absorbs primary light emitted from a light emitting element and has a longer wavelength than the primary light. Secondary light is emitted, the scattering material scatters the primary light and the secondary light, and the phosphor plate is composed of a single layer, from one surface of the phosphor plate. The average distance to the phosphor is longer than the average distance from the one surface to the scattering material.

Also, the specific gravity of the scattering material, the specific gravity of the phosphor may be characterized in different.

  In addition, the phosphor may have a particle size of 1/10 or less of the wavelength of the primary light. The phosphor may be a nanocrystal phosphor. The nanocrystalline phosphor may be made of a III-V group compound semiconductor containing In and P or a II-VI group compound semiconductor containing Cd and Se. The nanocrystalline phosphor may include at least one of InP or CdSe.

A light-emitting device according to the present invention is a light-emitting device including a light-emitting element, a package containing the light-emitting element and having an opening on a light extraction side, and a phosphor plate disposed in the opening, The phosphor plate is a phosphor plate made of a base material, a phosphor, and a scattering material, and the phosphor absorbs primary light emitted from the light emitting element, and has secondary light having a longer wavelength than the primary light. The scattering material scatters the primary light and the secondary light, and the phosphor plate is composed of a single layer, from the primary light incident surface of the phosphor plate. The average distance to the phosphor is longer than the average distance from the primary light incident surface to the scattering material. Further, the light emitting element may be an LED.

The manufacturing method of the phosphor plate which consists of a base material, a phosphor and a scattering material according to the present invention and which consists of a single layer includes a step of applying a base material containing a scattering material and a phosphor on a glass substrate, and the scattering material It is good also as including the process of settling only in the lower part of the above-mentioned substrate, and the process of hardening said substrate in this order. The scattering material may have a specific gravity larger than that of the phosphor.

  ADVANTAGE OF THE INVENTION According to this invention, the light extraction efficiency can be improved in the light-emitting device using a phosphor plate.

It is sectional drawing of the light-emitting device which concerns on Embodiment 1 of this invention. FIG. 5 is a diagram illustrating a manufacturing process of the phosphor plate according to the first embodiment. It is sectional drawing of the light-emitting device which concerns on Embodiment 2 of this invention. It is a figure which shows the manufacturing process of the fluorescent substance plate which concerns on Embodiment 2. FIG. It is sectional drawing of the light-emitting device which concerns on Embodiment 3 of this invention. It is sectional drawing of the conventional light-emitting device.

  Embodiments of the present invention will be described below 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 a light emitting device 100 including a phosphor plate according to the first embodiment of the present invention.
The light emitting device 100 faces the substrate 2 on which the electrode 1 is formed, the package 3 and the light emitting element 4 provided on the electrode 1, the wire 5 connecting the light emitting element 4 and the electrode 1, and the light emitting element 4. The phosphor plate 6 is arranged. The phosphor plate 6 is formed by laminating a scattering layer 61 and a phosphor layer 62 in order from the light emitting element 4. The scattering layer 61 includes a scattering material 611 and a resin 612 as a base material containing the scattering material 611. The phosphor layer 62 includes a phosphor 621 and a resin 622 as a base material containing the phosphor 621.

  The light-emitting device 100 shown in FIG. 1 is excited by blue primary light from the light-emitting element 4 and includes a red nanocrystalline phosphor and a green nanocrystalline phosphor, and is not used as excitation light. And secondary light from each phosphor can be mixed to obtain white light.

  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 reflectance, for example, a polymer resin in which metal oxide fine particles are dispersed is suitably used in addition to a ceramic material such as alumina or aluminum nitride. It is done.

  The package 3 has a high reflectance and is made of polyphthalamide or the like.

  The light emitting element 4 is used as a light source and preferably has a peak wavelength in the range of 360 nm to 470 nm. For example, a GaN LED, ZnO LED, organic EL, or the like having a peak wavelength at 450 nm can be used.

  The scattering material 611 constituting the scattering layer 61 uses particles made of an inorganic material having a high refractive index. For example, aluminum oxide, titanium oxide, silicon oxide, or the like can be used. The shape of the scattering material is not particularly limited, but a generally used bead shape is preferable, and the size is preferably about 10 times the wavelength of the light-emitting element 4 that is primary light. The resin 612 is made of a translucent resin material such as silicone. Other than silicone, any resin can be used as long as it is a resin in which the scattering material 611 is uniformly dispersed and is transparent and resistant to heat and light.

  The phosphor 621 constituting the phosphor layer 62 may be any phosphor. For example, a rare earth activated phosphor, a transition metal element activated phosphor, a III-V group compound semiconductor, or a II-VI group compound semiconductor is used. A phosphor can be used.

  The size of the phosphor is preferably a particle size of 1/10 or less of the wavelength of the primary light. The reason is that a phosphor having a particle size of 1/10 or less of the wavelength of the primary light has a size of 1/10 or less of the wavelength in the visible light region (380 to 780 nm), and hardly causes Mie scattering. Therefore, secondary light emitted from a certain phosphor is not backscattered by other phosphors, and the light extraction efficiency is improved. Furthermore, a phosphor having a particle size of 40 nm or less is particularly preferable.

  It is preferable to use nanocrystals as the phosphor. For example, InP-based nanocrystals can be used. When the particle size of InP is reduced, the band gap can be controlled in the range of blue (short wavelength) to red (long wavelength) by the quantum size effect, and the emission color can be freely changed. Furthermore, by optimizing the manufacturing conditions, the nanocrystal size distribution of nanocrystals is eliminated and a nanocrystal phosphor having a substantially uniform particle size is obtained, so that a narrow emission spectrum can be obtained.

  In addition, as a phosphor material, a phosphor that is a nanocrystal made of a group III-V compound semiconductor or a group II-VI compound semiconductor other than InP may be used. For example, as a nanocrystalline compound semiconductor composed of a III-V compound semiconductor or II-VI compound semiconductor, in a binary system, as a II-VI group compound semiconductor, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS , HgSe, HgTe, PbSe, PbS and the like. 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 said fluorescent substance 621, it is preferable to use the nanocrystal containing In and P or the nanocrystal containing Cd and Se. The reason is that 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 for this is that InP and CdSe are materials that have a small amount of constituent materials and are easy to produce, and also exhibit high quantum yields, and exhibit high luminous efficiency when irradiated with LED light. Here, the quantum yield 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 phosphor 621.

  The resin 622 is made of a translucent resin material such as silicone. Other than silicone, any resin can be used as long as it is a resin in which the phosphor 621 is uniformly dispersed and is transparent and resistant to heat and light.

  Next, a method for manufacturing the phosphor plate 6 will be described with reference to FIG. First, as shown in FIG. 2A, a resin 612 containing only a scattering material 611 is applied to a glass substrate 9 with a thickness of 100 to 500 μm, and allowed to stand for a predetermined time to be cured to produce a scattering layer 61. To do. The ratio of the resin 612 to the scattering material 611 was 10: 1 by weight. In this embodiment, aluminum oxide is used as the scattering material 611, and silicone resin (SCR1011 manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the resin 612. In addition to the SCR 1011, any resin can be used as long as it is a resin in which the scattering material 611 is uniformly dispersed and is transparent and resistant to heat and light.

  After the resin 612 is cured, as shown in FIG. 2B, a resin 622 containing only a predetermined amount of the phosphor 621 is applied on the scattering layer 61 with a thickness of 100 to 500 μm, and is allowed to stand for a predetermined time to be cured. Thus, the phosphor layer 62 is produced. The ratio between the resin 622 and the phosphor 621 was 10: 1 by weight. In the present embodiment, the phosphor 621 is a nanocrystalline phosphor emitting InP red (hereinafter referred to as a red nanocrystalline phosphor) and a nanocrystalline phosphor emitting InP green (hereinafter referred to as a green nanocrystalline phosphor). Was used at a weight ratio of 1:20. As the resin 622, the same silicone resin as described above was used. In addition to the SCR 1011, any resin can be used as long as it is a resin in which the phosphor 621 is uniformly dispersed and is transparent and resistant to heat and light.

  In the present embodiment, the scattering layer 61 and the phosphor layer 62 are applied so as to have substantially the same thickness, but the respective thicknesses may be appropriately adjusted according to the required light specifications. For example, when it is desired to scatter light more strongly, the scattering layer 61 is applied thicker. Further, the ratio of the scattering material 611 and the resin 612, the ratio of the phosphor 621 and the resin 622, or the ratio of the red nanocrystal phosphor and the green nanocrystal phosphor can be appropriately adjusted according to the required light specifications. That's fine. For example, when it is desired to obtain reddish light, the amount of red nanocrystal phosphor may be increased.

  After the resin 622 is cured, the phosphor plate 6 can be produced by peeling the glass substrate 9 from the phosphor plate 6 as shown in FIG. The phosphor plate 6 may be sandwiched between another glass plate without being peeled off from the glass substrate 9. Since the phosphor plate 6 can be protected from oxygen and moisture by being sandwiched between the two glass substrates 9, deterioration can be prevented.

  The phosphor plate 6 produced by the above procedure is attached to the LED package having the light emitting element 4 as shown in FIG. 1 so that the surface close to the light emitting element 4 becomes the scattering layer 61. Here, a GaN LED having a peak wavelength at 450 nm is used as the light emitting element 4. By attaching the phosphor plate 6 to the LED package so that the side closer to the light emitting element 4 becomes the scattering layer 61 in this way, the average distance from the incident surface of the primary light emitted from the light emitting element 4 to the phosphor 621 is The average distance to the scattering agent 611 is longer. By adopting such a configuration, since the scattering material 611 does not exist in the light path of the light emitted from the phosphor 621 toward the light emitting surface side of the phosphor plate 6, the light from the phosphor 621 is not emitted. The scattering material 611 does not return to the primary light incident surface side of the phosphor plate 6, and as a result, the light extraction efficiency can be improved. In addition, as a measuring method of the distance from the incident surface of the primary light to the phosphor, or the distance from the incident surface of the primary light to the scattering material, the cross section of a plurality of portions of the phosphor plate is observed with an SEM (scanning electron microscope), There is a method of measuring a linear distance from the incident surface of the primary light to the center of the phosphor or the scattering material.

  Of the secondary light emitted from the nanocrystalline phosphor excited by the primary light from the light emitting element 4, the light traveling toward the primary light incident surface side of the phosphor plate 6 is scattered by the scattering material 611 and phosphor plate 6. Toward the light exit surface side. Furthermore, since the nanocrystalline phosphor has a particle size of 1/10 or less of the wavelength of the primary light and does not scatter the secondary light (Mie scattering), the secondary light directed toward the light exit surface side of the phosphor plate 6 is The light is emitted from the phosphor plate 6 without being scattered on the primary light incident surface side. Therefore, the extraction efficiency of light emitted from the phosphor 621 can be improved.

  In the present embodiment, two types of phosphors, red and green, are used. However, the present invention is not limited to this, and one type of phosphor or three or more types of phosphors may be used. Depending on the required chromaticity of light, the type, the number of types, the amount, the ratio, and the like of the phosphor used may be appropriately adjusted.

<Embodiment 2>
Next, Embodiment 2 will be described. The present embodiment is different from the first embodiment in that the phosphor plate is formed of one resin layer.

  FIG. 3 is a cross-sectional view of a light emitting device 200 including the phosphor plate 6A according to the second embodiment. The phosphor plate 6A used in the light emitting device 200 is composed of the phosphor 621, the scattering material 611, and a resin 632 as a base material containing both of them, and is formed as a single layer.

  With reference to FIG. 4, the manufacturing process of phosphor plate 6A will be described. First, as shown in FIG. 4A, a resin 632 containing a predetermined amount of at least one phosphor 621 and a scattering material 611 is applied to a glass substrate 9 with a thickness of 100 to 500 μm. Note that a catalyst for promoting curing may be added to the resin 632. In this embodiment, aluminum oxide is used as the scattering material 611. Here, it is preferable that the specific gravity of the scattering material 611 is larger than that of the phosphor 621. InP red nanocrystalline phosphor and InP green nanocrystalline phosphor were used as the phosphor, and silicone resin (SCR1011 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the resin 622. The viscosity of the resin was 350 mPa · s in an environment of 23 ° C., and the ratio of the resin 632, the scattering material 611, and the phosphor 621 was 10: 1: 1 by weight. Further, as the phosphor 621, a red nanocrystal phosphor and a green nanocrystal phosphor were used at a weight ratio of 1:20.

  Next, as shown in FIG. 4B, the nanocrystalline phosphor lighter than the scattering material 611 is uniformly dispersed while the resin is cured for a predetermined time, while the specific gravity is larger than that of the phosphor. Therefore, the scattering material 611 having a high sedimentation speed settles at the bottom of the resin. In this way, a plate member is obtained in which the nanocrystalline phosphor is dispersed almost uniformly on the upper portion of the scattering material 611 and only the scattering material 611 is settled on the lower portion of the resin 632. After the resin 632 is cured, as shown in FIG. 4C, the phosphor plate 6A can be manufactured by peeling the resin from the glass substrate. The phosphor plate 6 may be sandwiched between another glass plate without being peeled off from the glass substrate 9. Since the phosphor plate 6A can be protected from oxygen and moisture by being sandwiched between the two glass substrates 9, deterioration can be prevented.

  The viscosity of the silicone resin used here was such that the nanocrystalline phosphor did not settle, was dispersed almost uniformly, and the scattering material 611 settled, but the viscosity was lower and the nanocrystalline fluorescence You may use the thing of the viscosity which both a body and the scattering material 611 settle. In that case, since the scattering material 611 having a specific gravity larger than that of the nanocrystalline phosphor has a fast sedimentation speed, the scattering material 611 settles first, and the nanocrystalline phosphor settles later, so that most of the scattering material 611 settles on the lower part of the resin. Since the phosphor settles on top of it, it is possible to produce a phosphor plate that is naturally substantially laminated.

  The phosphor plate 6A produced by the above procedure is attached to the LED package provided with the light emitting element 4 as shown in FIG. 1 so that the surface close to the light emitting element 4 is a surface with more scattering material. .

  With the light emitting device 200 having such a configuration, the manufacturing process of the phosphor plate 6A can be simplified. In particular, when a phosphor having a light specific gravity such as a nanocrystal phosphor is used as the phosphor 621, it is extremely effective. Moreover, even if it is not a nanocrystal fluorescent substance, it is realizable by adjusting the specific gravity of the scattering agent 611 more heavily than the fluorescent substance 621. FIG.

  In this embodiment, the specific gravity of the scattering material 611 is larger than the specific gravity of the phosphor. However, the present invention is not limited to this, and the specific gravity of the scattering material 611 is different from that of the fluorescent material, and the difference in sedimentation speed is used. Any method may be used as long as it is separated and cured.

<Embodiment 3>
Next, Embodiment 3 will be described. In the present embodiment, the phosphor layer 7 containing another type of nanocrystalline phosphor is formed on the phosphor plate 6B produced using only the red nanocrystalline phosphor 641 by the method described in the second embodiment. It is characterized in that it is laminated.

  FIG. 5 is a cross-sectional view of the light emitting device 300 according to the third embodiment. In the light emitting device 300, another type of phosphor layer 7 is laminated on the phosphor plate 6B. Specifically, a resin containing the green nanocrystalline phosphor 651 is applied on a phosphor plate containing the red nanocrystalline phosphor 641, left standing for a predetermined time, and cured. In the present embodiment, the phosphor layer 7 containing the phosphor plate 6B and the nanocrystalline phosphor 651 that emits green light has the same thickness, and is 100 to 500 μm.

  Here, in general, the phosphor absorbs light having energy larger than the respective excitation energy, and emits secondary light as fluorescence. For example, secondary light emitted from a phosphor having a large excitation energy such as a blue phosphor is absorbed by a phosphor having a small excitation energy such as a red phosphor, and it is difficult to obtain a desired color balance. Become. Therefore, as in this embodiment, by arranging phosphors having longer peak wavelengths on the side closer to the light emitting element 4 that emits primary light, the secondary light emitted by each phosphor is a phosphor that emits another color. The desired color balance can be easily obtained.

  As described above, as described in each of the embodiments, according to the present invention, in the light emitting device using the phosphor plate, it is possible to improve the light extraction efficiency of the phosphor.

DESCRIPTION OF SYMBOLS 1 Electrode 2 Substrate 3 Package 4 Light emitting element 5 Wire 6, 6A, 6B Phosphor plate 7 Phosphor layer 9 Glass substrate 61 Scattering layer 62 Phosphor layer 100, 200, 300 Light emitting device 611 Scattering material 612, 622, 632 Base material 621 Phosphor 641, 651 Nanocrystalline phosphor

Claims (9)

A phosphor plate comprising a substrate, a phosphor and a scattering material,
The phosphor absorbs primary light emitted from a light emitting element, and emits secondary light having a longer wavelength than the primary light.
The scattering material scatters the primary light and the secondary light,
The phosphor plate is formed of a single layer, and an average distance from one surface of the phosphor plate to the phosphor is longer than an average distance from the one surface to the scattering material. Phosphor plate.   2. The phosphor plate according to claim 1, wherein the specific gravity of the scattering material is different from the specific gravity of the phosphor. 3. The phosphor plate according to claim 1, wherein the phosphor has a particle size of 1/10 or less of the wavelength of the primary light. The phosphor plate according to claim 3 , wherein the phosphor is a nanocrystalline phosphor. 5. The phosphor plate according to claim 4, wherein the nanocrystalline phosphor is made of a III-V group compound semiconductor containing In and P or a II-VI group compound semiconductor containing Cd and Se. 6. The phosphor plate according to claim 5 , wherein the nanocrystalline phosphor contains at least one of InP and CdSe. A light emitting element;
A package containing the light emitting element and having an opening on the light extraction side;
A light emitting device including a phosphor plate disposed in the opening,
The phosphor plate is a phosphor plate made of a base material, a phosphor and a scattering material,
The phosphor absorbs primary light emitted from the light emitting element and emits secondary light having a longer wavelength than the primary light.
The scattering material scatters the primary light and the secondary light,
The phosphor plate is formed of a single layer, and an average distance from the primary light incident surface of the phosphor plate to the phosphor is longer than an average distance from the primary light incident surface to the scattering material. A light emitting device characterized. The light emitting device according to claim 7 , wherein the light emitting element is an LED. A method for producing a phosphor plate comprising a single layer comprising a substrate, a phosphor and a scattering material,
Applying a base material containing a scattering material and a phosphor to a glass substrate;
Sinking only the scattering material below the substrate;
The manufacturing method of the fluorescent substance board characterized by including the process of hardening the said base material in this order.