WO2013024684A1

WO2013024684A1 - Light emitting device, phosphor sheet, backlight system, and method of producing phosphor sheet

Info

Publication number: WO2013024684A1
Application number: PCT/JP2012/069161
Authority: WO
Inventors: 一規安念; 真和泉; 貴三子三枝
Original assignee: シャープ株式会社
Priority date: 2011-08-12
Filing date: 2012-07-27
Publication date: 2013-02-21
Also published as: JP2014199831A

Abstract

Provided is a light emitting device which is reduced in loss of light quantity, said light being emitted from a phosphor. A light emitting device which is provided with: a light emitting element that emits primary light; and a phosphor sheet which absorbs some of the primary light and emits secondary light. The phosphor sheet is provided with a light incident surface and a light exit surface, which face each other, and a light-reflecting lateral surface that reflects the light from the inside of the phosphor sheet.

Description

Light emitting device, phosphor sheet, backlight system, and phosphor sheet manufacturing method

The present invention relates to a light-emitting device used for illumination and a display, and in particular, includes a light source and a phosphor sheet containing a phosphor excited by a part of light output from the light source, and the light from the light source and fluorescence The present invention relates to a light emitting device that emits light from a body. The present invention also relates to a phosphor sheet used in the light emitting device, a backlight system using the light emitting device, and a method for manufacturing the phosphor sheet.

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 configured with a blue LED chip and a phosphor, a first method is to cover the blue LED chip by mixing the phosphor with a resin material, and a second method is a light emitting surface of the blue LED chip. There are various methods such as a method of directly applying the phosphor and a third method such as a method of placing a phosphor-containing sheet on a blue chip. The most commonly used method is the first method. However, in the case of the first method and the second method, heat due to the light emission of the blue LED directly affects the phosphor, so that depending on the type of the phosphor, the heat may cause deterioration. In particular, the nanocrystalline phosphor has high emission intensity and excellent color rendering and color reproducibility, but has a low heat-resistant temperature and is easily affected by heat. In addition, the surface where the phosphor is in contact with the outside is easily affected by oxygen and moisture, causing deterioration of the phosphor. Further, the resin may be deteriorated or discolored.

For this reason, a phosphor sheet in which a phosphor or a resin containing the phosphor is sandwiched between the glass and organic glass, which is the third method, has attracted attention. The phosphor sheet is easy to handle and is not easily affected by oxygen or moisture, and can be provided separately from the light emitting element, so that it is not directly affected by heat.

FIG. 13 is a schematic view of a light emitting device disclosed in Japanese Patent Laid-Open No. 2005-244075 (Patent Document 1). The light emitting device 100 disclosed in the patent document includes a light emitting element 101 that emits primary light, and a silicone that includes a phosphor that absorbs part of the primary light and emits secondary light having a wavelength equal to or greater than the wavelength of the primary light. A phosphor sheet 102 made of resin, and the phosphor sheet 102 includes two kinds of phosphors 103 and 104 having different excitation wavelength ranges.

FIG. 14 is a schematic diagram of a light emitting device disclosed in Japanese Patent Application Laid-Open No. 2007-317787 (Patent Document 2). The light-emitting device 200 disclosed in the patent document is formed of a material in which a phosphor 204 is sandwiched between light-transmitting plates 203 and sealed with a sealant 205 on the upper surface of a substrate 202 on which a light-emitting element 201 is placed. The phosphor sheet 208 is mounted via the reflection frame 206.

With the above structure, it is possible to obtain a light-emitting device including a phosphor that is hardly affected by oxygen, moisture, and heat and has little deterioration.

Japanese Patent Laid-Open No. 2005-244075 JP 2007-317787 A

However, when the light-emitting device in Patent Document 1 or Patent Document 2 is actually made to emit light, the light emission from the phosphor is lower than the directivity of the light-emitting element, so that the light from the light-emitting element passes through the phosphor sheet. In doing so, the wavelength-converted light of the phosphor is emitted in all directions, and part of the light is emitted from the side surface of the phosphor sheet. For this reason, when it is desired to irradiate the light of the light emitting device in a desired direction and space, the amount of light emitted from the phosphor may decrease. In addition, since there is light leaking from the side surface, the color balance may be lost. In this case, the originally required color cannot be obtained. For these reasons, it may be difficult to obtain ideal color reproducibility and brightness.

The present invention has been made in view of the above problems, and its purpose is a light-emitting device using a phosphor sheet, which reduces the loss of the amount of light emitted from the phosphor, ideal color rendering, The object is to provide a light emitting device having excellent color reproducibility, a phosphor sheet used in the light emitting device, a backlight system, and a method for producing the phosphor sheet.

The present invention is a light emitting device including a light emitting element that emits primary light and a phosphor sheet that absorbs a part of the primary light and emits secondary light, the phosphor sheets facing each other. A light incident surface and a light emission surface, and a light reflective side surface for reflecting light from the inside of the phosphor sheet.

In the light emitting device according to an embodiment of the present invention, the phosphor sheet includes a light reflecting film provided on a side surface. The light reflectivity is imparted by the light reflecting film.

In the light emitting device according to an embodiment of the present invention, the side surface of the phosphor sheet has a tapered shape that expands from the light incident surface toward the light emitting surface. The light reflectivity is imparted by the tapered side surface.

In the light emitting device of the present invention, the phosphor sheet preferably includes a phosphor layer containing a phosphor and two transparent layers provided so as to sandwich the phosphor layer.

In the light emitting device according to an embodiment of the present invention, the phosphor sheet includes a first phosphor layer including a first phosphor and a second phosphor that emits secondary light having a shorter wavelength than the first phosphor. A second phosphor layer, and in the phosphor sheet, a first phosphor layer and a second phosphor layer are laminated in this order from the light incident surface to the light emitting surface. At least one of the first phosphor and the second phosphor is preferably a phosphor made of nanocrystals.

In addition, the present invention is a phosphor sheet that is used in a light-emitting device including a light-emitting element that emits primary light, and absorbs a part of the primary light to emit secondary light. A light-emitting surface, and a light-reflecting side surface that reflects light from the inside of the phosphor sheet.

The phosphor sheet according to an embodiment of the present invention includes a light reflecting film provided on the side surface. The light reflectivity is imparted by the light reflecting film.

In the phosphor sheet according to an embodiment of the present invention, the side surface has a tapered shape that expands from the light incident surface toward the light emission surface. The light reflectivity is imparted by the tapered side surface.

The phosphor sheet of the present invention preferably includes a phosphor layer containing a phosphor and two transparent layers provided so as to sandwich the phosphor layer.

In the phosphor sheet according to an embodiment of the present invention, a first phosphor layer including a first phosphor and a second phosphor layer including a second phosphor that emits secondary light having a shorter wavelength than the first phosphor. The first phosphor layer and the second phosphor layer are laminated in this order from the light incident surface to the light emitting surface. At least one of the first phosphor and the second phosphor is preferably a phosphor made of nanocrystals.

The present invention is also a backlight system for video equipment including the above-described light emitting device.

Moreover, the manufacturing method of the fluorescent substance sheet of this invention is a method of manufacturing the above-mentioned fluorescent substance sheet in which the 1st transparent layer, the fluorescent substance layer containing fluorescent substance, and the 2nd transparent layer were laminated | stacked in this order. A step of pouring or applying the first transparent layer material into a die having a tapered shape whose side surfaces expand upward, and forming a first transparent layer; and a phosphor on the first transparent layer A step of casting or applying a phosphor layer material to form a phosphor layer, and a step of pouring or applying a second transparent layer material onto the phosphor layer to form a second transparent layer.

According to the present invention, in a light emitting device using a phosphor sheet, it is possible to obtain a light emitting device excellent in ideal color rendering and color reproducibility by reducing the loss of the amount of light emitted from the phosphor.

1 is a cross-sectional view of a light emitting device according to Embodiment 1. FIG. It is the perspective view and sectional drawing of a fluorescent substance sheet. It is sectional drawing which shows the manufacturing method of a fluorescent substance sheet. It is sectional drawing which shows the example of installation of a fluorescent substance sheet. It is a figure explaining the motion of the light of a fluorescent substance sheet. 6 is a cross-sectional view of a light emitting device according to Embodiment 2. FIG. It is a figure which shows the manufacturing method of a fluorescent substance sheet. It is sectional drawing which shows the example of installation of a fluorescent substance sheet. It is sectional drawing of the light-emitting device which concerns on Embodiment 3. FIG. It is sectional drawing of the light-emitting device which concerns on Embodiment 4. FIG. 6 is a cross-sectional view of a light emitting device according to Embodiment 5. FIG. It is sectional drawing of the backlight system which concerns on Embodiment 6. FIG. It is the schematic of the light-emitting device of a prior art example. It is the schematic of the light-emitting device of a prior art example.

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.

<Embodiment 1>
(Configuration of light emitting device)
FIG. 1 is a cross-sectional view of a light emitting device 10 according to the present embodiment. The light emitting device 10 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 that connects the light emitting element 4 and the electrode 1, and the light emitting element 4. The phosphor sheet 6 is arranged. The phosphor sheet 6 according to the present embodiment has a configuration in which the first transparent layer 61, the phosphor layer 62, and the second transparent layer 63 are sequentially laminated, and the light reflecting film 64 is formed on the side surface 6c. ing. Since the light reflecting film 64 is provided on the side surface 6c, the light traveling from the inner side of the phosphor sheet 6 toward the side surface 6c is reflected at a high reflectance on the side surface 6c or in the vicinity of the side surface 6c. The surface of the first transparent layer 61 opposite to the phosphor layer 62 is the light incident surface 6a, and the surface of the second transparent layer 63 opposite to the phosphor layer 62 is the light emitting surface 6b. The surface 6a and the light emitting surface 6b face each other. The light emission surface 6 b of the phosphor sheet 6 is also the light emission surface of the light emitting device 10.

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 the 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 high thermal conductivity and a high total reflectance, for example, a polymer resin in which metal oxide fine particles are dispersed in addition to a ceramic material such as alumina or aluminum nitride is suitable. Used.

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 preferably has a peak wavelength in the range of 360 nm to 470 nm. For example, a GaN-based light-emitting diode, ZnO-based light-emitting diode, or organic EL having a peak wavelength at 450 nm can be used.

FIG. 2A is a perspective view of the phosphor sheet 6, and FIG. 2B is a cross-sectional view of the phosphor sheet 6. The phosphor sheet 6 includes a first transparent layer 61, a phosphor layer 62, a second transparent layer 63, and a light reflecting film 64.

The first transparent layer 61 and the second transparent layer 63 are preferably transparent in the visible range and high in strength. For example, organic glass such as glass mainly composed of silicate and polycarbonate can be used. Since glass containing silicic acid as a main component has a high barrier property against gas moisture, it is possible to suppress deterioration of the phosphor and resin due to oxygen and moisture adhering to the phosphor layer 62. Moreover, organic glass has a softness | flexibility and can provide the flexible fluorescent substance sheet 6. FIG. In addition, the 1st transparent layer 61 and the 2nd transparent layer 63 may be formed with the same raw material, and may be formed with a different raw material.

Among the glasses containing silicate as a main component, it is preferable to use quartz glass. This is because quartz glass has a transmittance of about 95% in a wavelength region of 250 nm or more, and thus easily transmits LED light and fluorescence. Moreover, in the said organic glass, it is preferable to use PMMA (polymethyl methacrylate). PMMA has high weather resistance among organic glasses, so that deterioration such as coloring hardly occurs and it can be used for a long time.

The thickness of the first transparent layer 61 and the second transparent layer 63 can be appropriately determined according to the material and the like.

The phosphor layer 62 is composed of a resin layer containing a phosphor. Any phosphor may be used as long as it is a general phosphor. For example, a phosphor made of nanocrystals, a rare earth activated phosphor or a transition metal element activated phosphor can be used. In the present specification, “nanocrystal” refers to a crystal having a crystal diameter less than the exciton Bohr radius and in which exciton confinement or band gap increase due to the quantum size effect is observed.

Among them, it is particularly preferable to use a phosphor made of nanocrystals. The reason is that the diameter of the nanocrystal is smaller than the wavelength of visible light, and the primary light emitted from the light emitting element is not scattered (Mie scattering), so the directivity of the primary light is not lowered. As the phosphor made of nanocrystals, for example, InP-based nanocrystals 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 phosphor layer is formed by mixing and curing InP-based nanocrystals having a particle size that emits green light and a particle size that emits red light in a silicone resin or an acrylic resin.

In addition, a phosphor that is a nanocrystal made of a III-V compound semiconductor or II-VI compound semiconductor other than InP may be used as the phosphor material. 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 below.

And as said fluorescent substance, 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 easy to manufacture because of the small amount of constituent materials, and also show high quantum yield, and show 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.

The resin used for the phosphor layer 62 is preferably a resin in which the phosphor is uniformly dispersed, is transparent, and is resistant to heat and light. In addition, in order to prevent loss of light amount due to refraction at the boundary between the phosphor layer 62 and the first transparent layer 61 and the second transparent layer 63, the resin used in the phosphor layer 62 and the first transparent layer 61 and the second transparent layer 61 are used. It is preferable that there is no difference in the refractive index of the resin used in the transparent layer 63 or it is as small as possible. For example, when the first transparent layer 61 and the third transparent layer 63 are formed of acrylic glass such as PMMA, the phosphor layer 62 can also be made of a difference in refractive index by using an acrylic resin. Specifically, as the acrylic resin, polylauryl methacrylate (PLMA), PMMA or the like can be used.

The proportion of the phosphor contained in the phosphor layer 62 is not particularly limited, but can be, for example, 0.72% to 36% (weight%). The thickness of the phosphor layer 62 is not particularly limited, but can be, for example, 10 μm to 500 μm.

The light reflecting film 64 is preferably made of a material having a high reflectivity, and for example, silver or aluminum can be used. Silver has a light reflectance of about 98% in the wavelength region of 450 nm to 700 nm, and aluminum has a light reflectance of about 90% in the wavelength region of 280 nm to 1000 nm. Light and secondary light can be reflected without waste. Although the thickness of the light reflection film 64 is not particularly limited, it is preferable that the light reflection film 64 has a sufficient thickness so that light from the inside of the phosphor sheet 6 is reflected with high reflectance in the side surface 6c or in the vicinity of the side surface 6c.

The light reflecting film 64 is preferably configured to cover the entire side surface 6c. However, the portion of the side surface 6c where light from the phosphor 65 is likely to enter, for example, the phosphor layer 62 and the second transparent layer. The structure provided only in the part corresponding to the layer 63 may be sufficient.

(Method for manufacturing light emitting device)
Next, a specific example of a method for manufacturing the light emitting device 10 will be described below. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the phosphor sheet 6 used in the light emitting device 10. First, as shown in FIG. 3A, a silicone resin containing a predetermined amount of a nanocrystalline phosphor emitting red light and a nanocrystalline phosphor emitting green light is applied to the first transparent layer 61 to a thickness of 300 μm. The body layer 62 is formed. In the present embodiment, quartz glass having a thickness of 1 mm is used for the first transparent layer 61. A silicone resin (trade name: SCR1011) manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin forming the phosphor layer 62.

Next, as shown in FIG. 3B, the second transparent layer 63 is placed on the phosphor layer 62 and cured at room temperature. In the present embodiment, quartz glass having the same thickness as the first transparent layer 61 is used for the second transparent layer 63. In this way, the phosphor sheet 6 is formed.

Next, as shown in FIG. 3C, a light reflection film 64 is formed on the side surface of the phosphor sheet 6 by forming a silver film using a resistance heating vacuum deposition apparatus. In the present embodiment, the thickness of the light reflecting film 64 is 200 nm.

Next, as shown in FIG. 1, an LED package including an electrode 1, a substrate 2, a package 3, a light emitting element 4, and a wire 5 is prepared, and the phosphor sheet prepared by the above method on the LED package. 6 is installed.

FIG. 4 shows a state in which the phosphor sheet 6 is installed in the package 3. FIG. 4A shows an example in which an adhesive 31 is applied to the upper surface of the package 3 and the phosphor sheet 6 is placed thereon. The adhesive 31 may be any adhesive as long as the phosphor sheet 6 and the package 3 are securely fixed, but a silicone adhesive is preferable.

Alternatively, as shown in FIG. 4B, a method may be used in which a base 32 on which the phosphor sheet 6 is placed is placed on the upper surface of the package 3 and the phosphor sheet 6 is fitted into the base 32. Alternatively, the surface in contact with the side surface of the phosphor sheet 6 in the base 32 may have a shape that covers all the side surfaces of the phosphor sheet 6, and this surface may be covered with a light reflecting film 64 such as silver. Even in such a configuration, the side surface of the phosphor sheet 6 has a characteristic of reflecting light from the inside of the phosphor sheet 6 in a state where the phosphor sheet 6 is installed in the package 3. Moreover, according to this structure, the process of forming the light reflection film 64 can be omitted in the manufacturing process of the phosphor sheet 6.

Furthermore, as shown in FIG. 4 (c), the upper surface of the package 3 may be processed in advance so that the phosphor sheet 6 can be accommodated, and the phosphor sheet 6 may be fitted into that portion. The light emitting device is manufactured by the above procedure.

(Function of light reflecting film)
Here, the effect | action by the light reflection film | membrane 64 is demonstrated in detail using a specific example. FIG. 5 schematically shows the movement of the secondary light when the phosphor 65 that has absorbed the primary light emitted from the light emitting element 4 emits the secondary light. In practice, light is refracted at the boundary between the phosphor layer 62 and the first transparent layer 61 or the second transparent layer 62, between the phosphor sheet and the outside air. The refraction of the light of the part is omitted.

FIG. 5A shows a phosphor sheet 6 used in the light emitting device 10 according to this embodiment, and FIG. 5B shows a phosphor sheet 7 of a comparative example. The phosphor sheet 7 is different from the phosphor sheet 6 only in that it does not have the light reflection layer 64, and the other configuration is the same. Here, the first transparent layer 61 and the second transparent layer 63 of the phosphor sheets 6 and 7 are made of quartz, and the resin of the phosphor layer 62 is a silicone resin (trade name: SCR1011 manufactured by Shin-Etsu Chemical Co., Ltd.). is there. The refractive index of quartz is about 1.54, and the refractive index of SRC1011 is about 1.53. Thus, by using a material having a small difference in refractive index, loss of light amount due to light refraction can be prevented.

In FIG. 5A, the primary light L8 emitted from the light emitting element enters the phosphor sheet 6 from the light incident surface 6a, is absorbed by the phosphor 65, and the phosphor 65 emits secondary lights L1 to L5. . Among these, the secondary lights L2 to L4 are emitted from the light exit surface 6b as they are. As an example, as shown in FIG. 5A, the secondary light L1 travels while reflecting the inside of the phosphor layer 62, is reflected by the light reflecting film 64, and is emitted from the light emitting surface 6b. As an example, as illustrated in FIG. 5A, the secondary light L <b> 5 travels while reflecting inside the phosphor layer 62 sandwiched between the first transparent layer 61 and the second transparent layer 63, and the light reflecting film 64. And is emitted from the light exit surface 6b.

Here, a phosphor sheet 7 shown in FIG. 5B will be described as a comparative example. In FIG. 5B, the primary light L8 emitted from the light emitting element enters the phosphor sheet 7 from the light incident surface 7a, is absorbed by the phosphor 65, and the phosphor 65 emits secondary lights L1 to L5. . Among these, the secondary lights L2 to L4 are emitted from the light exit surface 7b as they are. As an example, as shown in FIG. 5B, the secondary light L <b> 1 travels while reflecting the inside of the phosphor layer 62 and is emitted from the side surface 7 c of the phosphor sheet 7. As an example, as shown in FIG. 5B, the secondary light L <b> 5 travels while reflecting the inside of the phosphor layer 62 sandwiched between the first transparent layer 61 and the second transparent layer 63, and the phosphor sheet 7. The light is emitted from the side surface 7c.

Thus, according to the phosphor sheet 7 shown in FIG. 5B, the secondary light L1 and L5 are not irradiated to the irradiated object provided facing the light emitting device, and the irradiated object is not irradiated. Irradiation light quantity will decrease. According to the phosphor sheet 6 having the light reflecting film 64 on the side surface, it is possible to prevent a decrease in the amount of light applied to the irradiated object.

<Embodiment 2>
(Configuration of light emitting device)
The second embodiment will be described with reference to FIG. In the light emitting device 20 of the second embodiment, the phosphor sheet 8 is used. The phosphor sheet 8 has a tapered shape in which the side surface 8c of the phosphor sheet 8 expands upward, and the side surface is perpendicular to the light incident surface and the light emitting surface, as shown in FIG. This is different from the phosphor sheet 6 used in the light emitting device. In the phosphor sheet 8, the side surface 8c is tapered so that the light exit surface 8b is larger than the light incident surface 8a. The phosphor sheet 8 has a configuration in which a first transparent layer 81, a phosphor layer 82, and a second transparent layer 83 are sequentially laminated, and a light reflection film 84 is provided along the tapered side surface 8c. . Details of each component are the same as those in the first embodiment, and thus description thereof is omitted.

Since the light reflecting film 84 is provided on the side surface 8c of the phosphor sheet 8, the light traveling from the inner side of the phosphor sheet 8 toward the side surface 8c is reflected with a high reflectance near the side surface c or the side surface 6c. Furthermore, since the side surface c has a tapered shape that expands upward, the incident angle of light incident on the side surface 8 c from the inside of the phosphor sheet 8 is increased, and a large amount of light is emitted without depending on the light reflecting film 84. Reflected by the side surface 8c.

(Method for manufacturing light emitting device)
Next, a specific example of a method for manufacturing the light emitting device 20 will be described below. FIG. 7 is a diagram illustrating a manufacturing process of the phosphor sheet 8 used in the light emitting device 20. First, as shown in FIG. 7A, a metal mold 800 is prepared. The cross section of the mold 800 has a trapezoidal shape with a wide upper portion and a narrow lower portion. That is, the side surface of the mold has a tapered shape that expands upward. The angle of the tapered side surface is determined by the required shape of the light emitting sheet 8. Next, as shown in FIG. 7B, a silicone resin as a first transparent layer material is poured or applied to a mold 87 and cured to form a first transparent layer 81. The degree of curing may not be completely cured as long as it is cured to the extent that it does not mix with the layer to be formed next.

Next, as shown in FIG. 7C, a resin containing a nanocrystalline phosphor as a phosphor layer material is poured or applied onto the first transparent layer 81 and cured to form a phosphor layer 82. Then, as shown in FIG. 7 (d), a silicone resin is poured or applied as a second transparent layer material on the phosphor layer 82 and cured to form the second transparent layer 83. When all the layers of resin are completely cured, the mold 87 is removed as shown in FIG. 7E, and silver is deposited as a light reflecting film 84 on the side surface 8c as shown in FIG. 7F. The silver deposition method is the same as that of the first embodiment. The materials used for the first resin layer 81, the phosphor layer 82, and the second resin layer 83 may be the same material, or may be different from each other or partially. Organic glass may be used as the first transparent layer material and the second transparent resin material. Organic glass, like resin, can be poured into a mold and cured.

In addition, the process of vapor-depositing silver shown in FIG.8 (f) is not performed, but in the state which arrange | positioned materials, such as silver, as the light reflection film 84 beforehand in the side surface of the metal mold | die 800 in FIG. It may be a method of manufacturing. The light reflecting film 84 is preferably formed so as to cover the entire side surface of the phosphor sheet 8, and may be formed larger than the side surface of the phosphor sheet 8. By forming in this way, it is possible to irradiate the secondary light in the target direction without waste.

FIG. 8 shows a state in which the phosphor sheet 8 is installed in the package 3. FIG. 8A shows the case where the adhesive 31 is applied to the upper surface of the package 3 and the phosphor sheet 8 is placed thereon. The adhesive 31 may be any material as long as the phosphor sheet 8 and the package are securely fixed, but a silicone-based adhesive is preferable.

Alternatively, as shown in FIG. 8 (b), a method may be used in which a stand 33 on which the phosphor sheet 8 is accommodated is installed on the upper surface of the package 3 and the phosphor sheet 8 is fitted into the stand 33. Alternatively, in the table 33, the surface in contact with the side surface of the phosphor sheet 8 is configured to cover the entire side surface of the phosphor sheet 8. By making the surface in contact with the side surface of the phosphor sheet 8 longer than the side surface of the phosphor sheet 8 in the table 33, the secondary light can be irradiated in the target direction more efficiently. Further, the surface of the table 33 that contacts the side surface of the phosphor sheet 8 may be covered with a light reflecting layer 84 such as silver. Even in such a configuration, the side surface of the phosphor sheet 8 has a characteristic of reflecting light from the inside of the phosphor sheet 8 in a state where the phosphor sheet 8 is installed in the package 3. Moreover, according to this structure, the process of forming the light reflection film 84 can be omitted in the manufacturing process of the phosphor sheet 8.

Furthermore, as shown in FIG. 8C, the upper surface of the package 3 may be processed in advance into a shape that can accommodate the phosphor sheet 6, and the phosphor sheet 6 may be fitted into that portion. The light emitting device 20 is manufactured by the above procedure.

By adopting such a configuration, the component irradiated in the unnecessary direction of the secondary light of the phosphor is reflected by the side surface or the light reflection film 84, and the light of the secondary light is irradiated in the direction of the target without waste. Can be made. Further, since the area of the light emitting surface 8b in the second transparent layer 83 is larger than the area of the light incident surface 8a of the primary light in the first transparent layer 81, the light out of the wavelength converted by the phosphor Since part of the light traveling downward can also be reflected upward, a brighter light emitting device can be obtained as compared with the first embodiment.

<Embodiment 3>
The third embodiment will be described with reference to FIG. In the light emitting device 30 of Embodiment 3, a phosphor sheet 80 is used. The phosphor sheet 80 is different from the phosphor sheet 8 used in the light emitting device of Embodiment 2 shown in FIG. 6 only in that the light reflecting film 84 is not provided. Details of each component are the same as those in the first and second embodiments, and thus the description thereof is omitted.

FIG. 9 shows the light emitting device 30 in the present embodiment. The phosphor sheet 80 used in the light emitting device 30 is manufactured by the manufacturing method shown in FIG. 7 of the second embodiment, and before forming the light reflecting film 84 shown in FIG. Is in state. In addition, the manufacturing method will not be limited if the side surface of the fluorescent substance sheet 80 is formed in the taper shape which expands upwards, and it is comprised so that a light-projection surface may become larger than a light-incidence surface.

In FIG. 9, the primary light L8 emitted from the light emitting element is absorbed by the phosphor 85, and the phosphor 85 emits secondary lights L1 to L7. Among these, the secondary lights L3 to L5 are emitted as they are from the upper surface of the light emitting device 30 which is the light emitting surface 8b. The secondary lights L1, L2, L6, and L7 travel through the phosphor layer 82, are reflected by the side surface 8c of the phosphor sheet 80, and are emitted from the upper surface of the light emitting device 30 that is the light emitting surface 8b.

When the side surface of the phosphor sheet is not tapered and is a side surface perpendicular to the light incident surface and the light exit surface as shown in FIG. 5B, the incident angle of the secondary light to the side surface becomes small. Therefore, like the secondary light L1 and the secondary light L5 shown in FIG. 5B, light is easily emitted from the side surface, and the amount of light emitted from the light emitting surface 8b is reduced.

As in this embodiment, the side surface of the phosphor sheet is formed in a tapered shape, and the area of the light emitting surface 8b of the phosphor sheet is larger than the area of the light incident surface 8a, thereby reducing the amount of irradiation light. It becomes possible to prevent.

<Embodiment 4>
A fourth embodiment will be described with reference to FIG. In the light emitting device 40 of the fourth embodiment, the phosphor sheet 60 is used. The phosphor sheet 60 is different from the phosphor sheet 6 used in the light emitting device of Embodiment 1 shown in FIG. 1 in that two phosphor layers are laminated. In the phosphor sheet 60, a first transparent layer 61, a first phosphor layer 621, a second phosphor layer 622, and a second transparent layer 63 are laminated in order from the light incident surface 6a side. The first phosphor layer 621 and the second phosphor layer 622 include different nanocrystalline phosphors. The second phosphor included in the second phosphor layer 622 preferably emits secondary light having a shorter wavelength than the first phosphor included in the first phosphor layer 621. For example, the first phosphor is a nanocrystalline phosphor that emits red light, and the second phosphor is a nanocrystalline phosphor that emits green light.

The reason why the second phosphor preferably emits secondary light having a shorter wavelength than the first phosphor is that the phosphor absorbs light having energy larger than the respective excitation energy, and the fluorescence As a secondary color. For example, secondary light emitted from a phosphor having a large excitation energy such as a blue phosphor is easily absorbed by a phosphor having a small excitation energy such as a red phosphor. Therefore, by laminating in order of phosphors with long peak wavelengths in the order of the optical path of the primary light, the secondary light emitted from each phosphor is hardly absorbed again by the phosphors emitting other colors, and the desired color Balance can be easily obtained. Details of each component are the same as those in the first embodiment, and thus description thereof is omitted.

<Embodiment 5>
Embodiment 5 will be described with reference to FIG. In the light emitting device 50 of the fifth embodiment, a phosphor sheet 86 is used. The phosphor sheet 86 is different from the phosphor sheet 8 used in the light emitting device of Embodiment 2 shown in FIG. 6 in that two phosphor layers are laminated. In the phosphor sheet 80, a first transparent layer 81, a first phosphor layer 821, a second phosphor layer 822, and a second transparent layer 83 are laminated in order from the light incident surface 8a side. The first phosphor layer 821 and the second phosphor layer 822 include different nanocrystalline phosphors. The second phosphor included in the second phosphor layer 822 preferably emits secondary light having a shorter wavelength than the first phosphor included in the first phosphor layer 821. For example, the first phosphor is a nanocrystalline phosphor that emits red light, and the second phosphor is a nanocrystalline phosphor that emits green light. The reason why it is preferable that the second phosphor emits secondary light having a shorter wavelength than that of the first phosphor is as described in the fourth embodiment.

By adopting such a configuration, as in the fourth embodiment, secondary light emitted from each phosphor is hardly absorbed again by phosphors emitting other colors, and a desired color balance can be easily obtained. Obtainable. Further, as in the second embodiment, part of the light traveling downward in the secondary light of the phosphor can be reflected upward by the light reflecting film 84, so that a bright illumination device without loss is obtained. Can do. Details of each component are the same as those in the second embodiment, and thus description thereof is omitted.

<Embodiment 6>
A side edge type backlight system according to Embodiment 6 will be described with reference to FIG. The side edge type backlight system according to the present embodiment includes the light emitting device 10 according to the first embodiment, the light guide plate 91, and the reflection plate 92. In the present embodiment, the primary light and the secondary light emitted from the light emitting device 10 enter the light guide plate 91 and are reflected by the reflection plate 92, so that the primary light and the secondary light are transmitted from the surface facing the reflection plate 92. It has a structure to take out.

By covering the side surface of the phosphor sheet 6 with the light reflecting film 64, it is possible to reduce the loss of light emitted outside without being incident on the light guide plate 7. Therefore, for example, the backlight system of the present embodiment can be used for a backlight system of video equipment such as a television. When the backlight system of this embodiment is used, the brightness of display can be improved in video equipment. In the present embodiment, the example in which the light emitting device of the present invention is used in the side-edge type backlight system has been described. In the present embodiment, the light emitting device 10 of the first embodiment is used, but the light emitting device of any of the above embodiments may be used.

As described above, in a light emitting device using a phosphor sheet, a side surface having light reflectivity can be formed by using a light reflecting film on the phosphor sheet or forming a side surface in a tapered shape. By reducing the loss of light emitted from the body, it is possible to realize a light emitting device that is bright and has excellent ideal color rendering and color reproducibility.

It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

The light-emitting device according to the present invention is suitable as a light-emitting device including a semiconductor light-emitting element that emits primary light and a phosphor sheet that includes a phosphor that absorbs the primary light and emits secondary light.

1 electrode, 2 substrate, 3 package, 4 light emitting element, 5 wire, 6, 7, 8, 9, 61, 80, 86 phosphor sheet, 6a, 7a, 8a light incident surface, 6b, 7b, 8b

light emitting surface

6c, 7c, 8c side, 61, 81 first transparent layer, 62, 82 phosphor layer, 621, 821 first phosphor layer, 622, 822 second phosphor layer, 63, 83 second transparent layer, 64 , 84 light reflection film, 87 mold, 91 light guide plate, 92 reflection plate.

Claims

A light emitting element that emits primary light;
A light emitting device comprising a phosphor sheet that absorbs a portion of the primary light and emits secondary light,
The phosphor sheet includes a light incident surface and a light exit surface that face each other, and a side surface having light reflectivity that reflects light from the inside of the phosphor sheet.
The light emitting device according to claim 1, wherein the phosphor sheet includes a light reflecting film provided on the side surface.
The light-emitting device according to claim 1, wherein a side surface of the phosphor sheet has a tapered shape that expands from the light incident surface toward the light emitting surface.
The light-emitting device according to claim 1, wherein the phosphor sheet includes a phosphor layer containing a phosphor and two transparent layers provided so as to sandwich the phosphor layer.
The phosphor sheet includes a first phosphor layer including a first phosphor and a second phosphor layer including a second phosphor that emits secondary light having a shorter wavelength than the first phosphor,
2. The light emitting device according to claim 1, wherein in the phosphor sheet, a first phosphor layer and a second phosphor layer are laminated in this order from the light incident surface to the light emitting surface.
6. The light emitting device according to claim 5, wherein at least one of the first phosphor and the second phosphor is a phosphor made of nanocrystals.
A phosphor sheet that is used in a light-emitting device including a light-emitting element that emits primary light and absorbs a part of the primary light to emit secondary light,
A phosphor sheet comprising: a light incident surface and a light exit surface that face each other; and a light-reflecting side surface that reflects light from the inside of the phosphor sheet.
The phosphor sheet according to claim 7, comprising a light reflecting film provided on the side surface.
The phosphor sheet according to claim 7, wherein the side surface has a tapered shape that expands from the light incident surface toward the light emitting surface.
The phosphor sheet according to claim 7, comprising a phosphor layer containing a phosphor and two transparent layers provided so as to sandwich the phosphor layer.
A first phosphor layer including a first phosphor and a second phosphor layer including a second phosphor that emits secondary light having a shorter wavelength than the first phosphor;
The phosphor sheet according to claim 7, wherein a first phosphor layer and a second phosphor layer are laminated in this order from the light incident surface to the light emitting surface.
The phosphor sheet according to claim 11, wherein at least one of the first phosphor and the second phosphor is a phosphor made of nanocrystals.
A backlight system for video equipment, comprising the light emitting device according to claim 1.
The method for producing a phosphor sheet according to claim 9, wherein the first transparent layer, the phosphor layer containing the phosphor, and the second transparent layer are laminated in this order,
A step of pouring or applying a first transparent layer material into a mold having a tapered shape whose side surfaces expand upward, and forming a first transparent layer;
Pouring or applying a phosphor layer material containing the phosphor on the first transparent layer to form a phosphor layer;
Forming a second transparent layer by pouring or applying a second transparent layer material onto the phosphor layer.