JP2009277998A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device that emits light uniformly and stably with high efficiency, while variation in light emission color among a plurality of LED lamps is suppressed. <P>SOLUTION: The light-emitting device includes a light-emitting element, such as a blue LED chip; and a phosphor-containing resin layer containing two or more phosphors having approximate specific gravities and a transparent resin whose specific gravity is 20% or higher of the specific gravity of the phosphor having the largest specific gravity among those phosphors. The two or more phosphors preferably have similar shapes, and also, preferably, have approximate mean particle diameters (D50: 7 to 20 μm). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device such as a light emitting diode lamp.

  LED lamps using light emitting diodes (LEDs) are rapidly expanding in various fields such as backlights for liquid crystal displays, mobile phones, information terminals, and indoor / outdoor advertisements. In addition, LED lamps have features such as long life, high reliability, low power consumption, impact resistance, high purity display color, lightness, thinness, and other features. Application is also being attempted. When such an LED lamp is applied to various uses, it is important to obtain white light emission.

  Typical methods for realizing white light emission with an LED lamp are (1) a method using three LED chips that emit light in blue, green and red colors, and (2) a blue light emitting LED chip and yellow or orange light emission. And (3) a method of combining an ultraviolet light emitting LED chip and a blue, green and red light emitting three-color mixed phosphor. Generally, among these, the method (2) is widely used.

  As an LED lamp to which the above-described method (2) is applied, a phosphor dispersion liquid in which a phosphor is mixed and dispersed in a transparent resin is poured into a cup-shaped frame equipped with an LED chip, and this is solidified. A dispersion type in which a resin layer containing a phosphor is formed has been proposed (for example, see Patent Document 1). In addition to such bullet-type and SMD (Surface Mounting Device) type LED lamps, a plurality of LED chips are mounted on a substrate (board) for the purpose of high brightness, and a phosphor-containing resin layer is used. A coated chip on board (COB) type has been developed and attracts attention.

  The characteristics required for LED lamps for general illumination include color rendering as an index of color appearance in addition to high luminous efficiency. Color rendering is an evaluation of the color appearance of a light source using light that is close to natural light as the reference light, and the color shift when the test color specified in JIS is illuminated with the sample light source and the reference light, respectively. The numerical value of the size is the color rendering index. The color rendering index includes an average color rendering index Ra and a special color rendering index Ri. The average color rendering index Ra is determined by test No. It is expressed as an average value of the color rendering index of 1 to 8, and the special color rendering index Ri is the test number. Expressed as individual special color rendering index of 9-15. The average color rendering index Ra is an index indicating whether the color of the white light source, which is a reference light source, is faithfully reproduced.

  In general, in a so-called high color rendering type LED lamp with a high average color rendering index Ra, in addition to yellow phosphors emitting yellow or orange light, red phosphors such as nitrides and sulfides are emitted. The color rendering properties have been improved by blending of. However, the red phosphor absorbs not only the blue light having a wavelength of 460 nm from the LED chip but also the light between the green light and the yellow light emitted from the yellow phosphor, and is used for excitation. However, there is a problem that the luminous efficiency of the LED lamp is significantly lowered.

  Therefore, recently, by using a green phosphor whose main emission wavelength is around 500 nm in combination, filling the valley of the emission spectrum between the blue light emission from the LED chip and the light emission from the yellow phosphor, as much as possible Attempts have been made to further improve Ra by approaching the spectrum of sunlight (see, for example, Patent Document 2). Furthermore, the lineup of up to 6500K, 5000K, 4200K, and 3000K (2850K in some cases) is required for the color temperature as the light color in correspondence with HID lamps, light bulbs, fluorescent lamps, etc. Desired efficiency and average color rendering index Ra are required. Therefore, in LED lamps for illumination, the tendency to mix phosphors in order to meet various requirements is increasing. Conventionally, in order to obtain a desired color tone by color mixing, the type of phosphor is selected by paying attention to the main wavelength of light emission, and a plurality of types of phosphors are combined and blended.

  However, in such a selection and blending method, in the phosphor dispersion liquid in which a plurality of types of phosphors are added to and mixed with a transparent resin such as a silicone resin, the dispersion state of each phosphor particle tends to be uneven. And the dispersion state of the phosphor particles in each part (for example, the upper part and the lower part) of such a phosphor dispersion liquid tends to become more and more non-uniform over time.

When a dispersion liquid in which the phosphor particles are dispersed in a non-uniform manner is applied and mounted on the LED chip to produce a plurality of LED lamps, the emission color (color tone) varies among the LED lamps. There was a problem that became larger. Moreover, not only the variation in emission color among the plurality of LED lamps, but also in one LED lamp, the light emission in the phosphor-containing resin layer becomes uneven in each part, and stable and highly efficient light emission is achieved. There was a problem that it could not be obtained.
JP 2001-148516 A JP 2003-327518 A

  The present invention has been made to solve such a problem, and provides a light-emitting device capable of suppressing uniform variations in emission color among a plurality of LED lamps and obtaining uniform, stable and highly efficient light emission. It is an object.

  The light-emitting device according to claim 1 includes: a light-emitting element; and two or more kinds of phosphors that emit visible light having different principal wavelengths when excited by light emitted from the transparent resin and the light-emitting element. The two or more types of phosphors have an approximate specific gravity, and the transparent resin has a specific gravity of 20% or more of the phosphor having the largest specific gravity among the phosphors. And a phosphor-containing resin layer having a specific gravity.

  The light emitting device according to claim 2 is characterized in that, in the light emitting device according to claim 1, the difference in specific gravity between the two or more kinds of phosphors is 2 or less.

  In the first and second aspects of the invention described above, the definitions and technical meanings of terms are as follows unless otherwise specified.

  The light emitting element emits visible light by exciting a phosphor with emitted light. Examples of the light emitting device used in the present invention include a blue light emitting type LED chip and an ultraviolet light emitting type LED chip. However, the light-emitting element is not limited to these, and any light-emitting element capable of emitting visible light by exciting the phosphor may have various light emission depending on the use of the light-emitting device and the target light emission color. An element can be used.

  Such a light emitting element is mounted on a base material, for example. The base material has a substrate having a wiring portion such as a circuit pattern or a lead terminal, for example, and the light emitting element is mounted on the substrate. Further, a frame having a concave portion opened to the outside may be arranged on the substrate, and the base material may be constituted by this frame and the substrate. Further, the concave material is directly formed on the substrate without using the frame, and the base material is formed. It is good. Thus, when a base material has a recessed part, a light emitting element is arrange | positioned in a recessed part.

  The phosphor is excited by light emitted from such a light emitting element (for example, blue light) to emit visible light, and a desired light-emitting device is obtained by mixing colors of the visible light and the light emitted from the light emitting element. A light emission color is obtained. In the present invention, as the phosphor, two or more kinds of phosphors having different emission main wavelengths are used. In addition, about the kind of fluorescent substance, the same kind, the number of elements, and the combination which comprise a fluorescent substance shall be the same kind of fluorescent substance even if a composition is not the same.

  These two or more types of phosphors both have approximate specific gravity. Here, the specific gravity is approximate as long as the relationship has the function of the present invention, but a preferable range is that the specific gravity difference between the phosphors is 2 or less, that is, The difference between the specific gravity value of the phosphor with the highest specific gravity and the specific gravity value of the phosphor with the lowest specific gravity is 2 or less.

  If the difference in specific gravity of the phosphor is 2 or less, even if a relatively long time elapses after the phosphor dispersion liquid is prepared, variations in emission color are unlikely to occur. Therefore, for example, when an arbitrary amount of the phosphor dispersion liquid is used in the manufacturing process of a plurality of light emitting elements, variation in emission color of each light emitting element is suppressed, so that product quality and productivity are effectively improved. Can be improved. From the point of uniformity of the dispersion state of each phosphor, the difference in specific gravity between the phosphors is preferably as small as possible, and it is most preferable to use two or more types of phosphors having the same specific gravity.

  Moreover, it is preferable that these two or more types of phosphor particles have similar shapes and have similar particle sizes.

  Here, the similar shape means the following. That is, the shape of the phosphor particles can be divided into four groups: spherical, elliptical spherical (or rugby ball), plate, and needle, and those classified into each group are similar. It shall have the shape.

  The features of the four shapes can be represented by the value of minor axis / major axis, and those having a value of 1.0 to 0.9 are spherical, those of 0.8 to 0.4 are elliptical, A thing of 0.35 or less can also be prescribed | regulated as a needle shape. In addition, a plate-shaped thing may be sufficient. Then, phosphors having the same shape group defined by the value of the minor axis / major axis can be made similar to each other. Moreover, it is also possible to make the phosphors having the same minor axis / major axis value the same or very close to each other in a similar shape.

  In the present invention, the phosphor particles may have an average particle size. In particular, it can indicate D50 with an average value of 50% of the integrated value of the particle size distribution. The average particle diameter (D50) indicates the size of particles that are accumulated from a low particle diameter and reach 50% by volume of the total amount of phosphor, and can be measured, for example, by a laser diffraction method.

  The phosphor-containing resin layer is formed as a layer obtained by mixing and dispersing these phosphors in addition to a transparent resin such as a silicone resin or an epoxy resin. It can be formed so as to cover the outside of the light emitting element. As the transparent resin, a phosphor having a specific gravity of 20% or more of the specific gravity of the phosphor having the largest specific gravity is used.

  According to the light emitting device of the first aspect, two or more kinds of phosphors have approximate specific gravity, and the dispersion state of each phosphor in the phosphor dispersion liquid becomes uniform. It is possible to reduce the variation in color tone that occurs or the variation in color tone that occurs between a plurality of light emitting units within a single light emitting device. In addition, since the transparent resin in which these phosphors are mixed and dispersed is configured to have a specific gravity of 20% or more of the phosphor having the largest specific gravity among the phosphors, the fluorescence in the phosphor dispersion liquid Sedimentation of the body is less likely to occur. For this reason, the phosphor content ratio of each part (for example, the upper part and the lower part) of the phosphor dispersion liquid is less likely to change over time and is stabilized, and variations in emission color are reduced.

  According to the light emitting device of claim 2, since the difference in specific gravity between two or more kinds of phosphors is 2 or less, the variation in emission color between the plurality of light emitting devices or between the plurality of light emitting units is further increased. Can be reduced.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that, in the plurality of drawings referred to below, the same or corresponding parts are denoted by the same reference numerals. FIG. 1 is a cross-sectional view showing the configuration of an LED lamp as a first embodiment of a light-emitting device of the present invention. FIG. 2 is a diagram of the LED lamp shown in FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2.

  The LED lamp 1 shown in FIGS. 1 to 3 has an LED chip 2 as a light emitting element. As the LED chip 2, for example, a blue light emitting type LED chip is used. The LED chip 2 is mounted on a circuit pattern 5 provided on a substrate 3 via an electrical insulating layer 4.

  The substrate 3 is made of a flat plate made of aluminum (Al), nickel (Ni), glass epoxy or the like having heat dissipation and rigidity. The circuit pattern 5 is made of an alloy of copper (Cu) and nickel (Ni), gold (Au), or the like, and has circuit patterns 5 on the anode side and the cathode side. The LED chip 2 is placed on one (for example, the anode side) circuit pattern 5 and the bottom electrode is electrically connected, and the top electrode is electrically connected to the other (for example, the cathode side) circuit pattern 5 by the bonding wire 6. It is connected to the. On the substrate 3, there is provided a frame 8 that forms a truncated cone-shaped recess 7 that gradually increases in diameter upward, and the LED chip 2 is disposed in the recess 7. The frame 8 is made of, for example, polybutylene terephthalate (PBT), polyphthalamide (PPA), polycarbonate (PC) or the like, and the recess 7 has a truncated cone shape with a depth of 0.5 to 1.0 mm, for example. Is formed.

  In the recess 7 in which the LED chip 2 is disposed, a phosphor-containing resin layer 9 mainly including a transparent resin (thermosetting resin) and containing two or more kinds of phosphors having different main wavelengths is provided. The LED chip 2 is sealed in the recess 7 by the phosphor-containing resin layer 9. Two or more kinds of phosphors having different main wavelengths have a specific gravity difference of 2 or less, that is, the specific gravity difference between the phosphor having the largest specific gravity and the phosphor having the smallest specific gravity is 2 or less. Specific gravity. Further, the transparent resin containing these phosphors has a specific gravity of 20% or more of the specific gravity of the phosphor having the largest specific gravity.

  Furthermore, it is preferable that two or more types of phosphors have similar shapes. That is, the particle shape of two or more kinds of phosphors is the same, such as whether they are all spherical, elliptical spherical (or rugby ball), plate-like, or needle-like. Belongs to the group shape. It is more preferable that the two or more types of phosphor particles have a spherical shape. The spherical shape includes not only a true spherical shape having a minor axis / major axis value of exactly 1.0 but also a shape close to a spherical shape (for example, a minor axis / major axis value of 1.0 to 0.9).

  Moreover, it is preferable that the two or more kinds of phosphors having such similar particle shapes have an average particle diameter (D50) in the range of 7 to 20 μm, and have an extremely approximate average particle diameter (D50). . The average particle diameter (D50) indicates the size of particles that are accumulated from a low particle diameter and reach 50% by volume of the total amount of phosphor, and can be measured, for example, by a laser diffraction method.

  When the average particle diameter (D50) of the phosphor particles is less than 7 μm, it is difficult to obtain sufficient luminous efficiency. On the other hand, when the thickness exceeds 20 μm, for example, when a phosphor is mounted using a dispenser, there arises a problem that the nozzle is clogged. The average particle diameter (D50) of the phosphor particles can be controlled, for example, by performing a classification process such as sieving in the manufacturing process.

  The phosphor-containing resin layer 9 is prepared by injecting a phosphor-containing resin (phosphor dispersion) in which two or more kinds of phosphors are mixed and dispersed in a liquid transparent resin (thermosetting resin) with an injection device such as a dispenser. It is formed by injecting into the concave portion 7 in which the LED chip 2 is disposed and heat curing. Examples of the transparent resin include a silicone resin and an epoxy resin. The use of a liquid silicone resin is preferred, and the use of a silicone resin having a viscosity at 25 ° C. of 1 to 70 Pa · s is particularly preferred from the viewpoint of ease of injection. The injection amount of the phosphor-containing resin in which two or more kinds of the phosphors are mixed and dispersed is approximately 5 to 10 mg. In the drawing, the upper surface of the phosphor-containing resin layer 9 is formed to be substantially flush with the upper end of the recess 7, but is not particularly limited thereto. The main wavelengths of the two or more kinds of phosphors to be contained in the transparent resin are not particularly limited, and can be appropriately selected according to the emission color of the target LED lamp 1 or the like.

As the phosphor, for example, a yellow phosphor that is excited by blue light emitted from the blue light emitting type LED chip 2 and emits light between yellow light and orange light is used. Further, at least one of a green or yellow-green phosphor having a dominant wavelength of 500 to 535 nm and a red phosphor having a dominant wavelength of 630 to 650 nm can be used together with the yellow phosphor. Here, as a yellow phosphor that is excited by blue light and emits light between yellow light and orange light, for example, RE ₃ (Al, Ga) ₅ O ₁₂ : Ce phosphor (RE is Y, Gd, and La). YAG phosphors such as AE ₂ SiO ₄ : Eu phosphor (AE represents an alkaline earth element such as Sr, Ba, Ca, etc. The same shall apply hereinafter.) Silicate phosphors such as Sr ₃ SiO ₅ : Eu ²⁺ phosphor, sialon-based phosphors (eg, Ca _x Si _y Al _z ON: Eu ²⁺ ), and Ca ₃ Sc ₂ O ₄ : Ce fluorescence There are bodies, etc., and these are selected. Examples of the green or yellow-green phosphor include YAG phosphors such as RE ₃ (Al, Ga) ₅ O ₁₂ : Ce phosphor, AE ₂ SiO ₄ : Eu phosphor, and Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce. There are silicate phosphors such as phosphors, sialon-based phosphors (for example, Ca _x Si _y Al _z ON: Eu ²⁺ ), and Ca ₃ Sc ₂ O ₄ : Ce phosphors, which are selected from these The Examples of red phosphors include oxysulfide phosphors such as La ₂ O ₂ S: Eu phosphors, nitride phosphors (for example, AE ₂ Si ₅ N ₈ : Eu ²⁺ , CaAlSiN ₃ : Eu ²⁺ ), and the like. Although used, it is not particularly limited.

  In the LED lamp 1 configured as described above, the applied electric energy is converted into blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm) by the LED chip 2 and emitted, and the emitted blue light is phosphor. Two or more kinds of phosphors contained in the containing resin layer 9 are converted into light having a longer wavelength. And the white light which is a color based on the blue light radiated | emitted from LED chip 2, and the luminescent color of these fluorescent substance is discharge | released from the LED lamp 1. FIG. In the LED lamp 1, two or more types of phosphors have similar specific gravity, and the transparent resin in which these phosphors are mixed and dispersed is the fluorescent material having the largest specific gravity among the phosphors. Since it is configured to have a specific gravity of 20% or more of the body, the dispersion state of the respective phosphor particles in the phosphor dispersion liquid becomes uniform, and the precipitation of the phosphor in the phosphor dispersion liquid hardly occurs. . Therefore, the phosphor content ratios of the respective parts (for example, the upper part and the lower part) of the phosphor dispersion liquid are less likely to change with time and are stable, and the variation in emission color that occurs between the plurality of LED lamps 1 can be reduced.

  4 and 5 show a light-emitting device that forms an LED package, which is the second embodiment of the light-emitting device of the present invention. 4 is a plan view of the light emitting device, and FIG. 5 is a longitudinal sectional view of the light emitting device shown in FIG. 4 cut along the line FF. 4 and 5, the same components as those of the light emitting device according to the first embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  A light-emitting device (LED lamp) 1 shown in FIGS. 4 and 5 includes a package substrate such as a device substrate 3, a reflective layer 31, a circuit pattern 5, a plurality of semiconductor light-emitting elements such as LED chips 2, and an adhesive layer. 32, a reflector 34, a phosphor-containing resin layer 9, and a light diffusing member 33. The phosphor-containing resin layer 9 also functions as a sealing member.

  The device substrate 3 is made of a flat plate made of a metal or an insulating material such as a synthetic resin, and has a predetermined shape such as a rectangular shape in order to obtain a light emitting area required for the light emitting device 1. When the device substrate 3 is made of a synthetic resin, it can be formed of, for example, an epoxy resin containing glass powder. When the device substrate 3 is made of metal, the heat radiation from the back surface of the device substrate 3 is improved, the temperature of each part of the device substrate 3 can be made uniform, and the semiconductor light emitting element 2 that emits light in the same wavelength range. The variation in the emission color can be suppressed. In addition, as a metal material which has such an effect, the material excellent in the heat conductivity of 10 W / m * K or more, specifically, aluminum or its alloy can be illustrated.

  The reflective layer 31 is sized so that a predetermined number of semiconductor light emitting elements 2 can be disposed, and is, for example, attached to the entire surface of the device substrate 3. The reflective layer 31 can be made of a white insulating material having a reflectance of 85% or more in the wavelength region of 400 to 740 nm. As such a white insulating material, a prepreg made of an adhesive sheet can be used. Such a prepreg can be formed, for example, by impregnating a sheet base material with a thermosetting resin mixed with a white powder such as aluminum oxide. The reflective layer 31 is bonded to the entire surface of the device substrate 3 by its own adhesiveness.

  The circuit pattern 5 is bonded to a surface of the reflective layer 31 opposite to the surface to which the device substrate 3 is bonded as an energizing element for each semiconductor light emitting element 2. For example, the circuit patterns 5 are formed in two rows dotted at predetermined intervals in the longitudinal direction of the device substrate 3 and the reflective layer 31 in order to connect the semiconductor light emitting elements 2 in series. The end-side circuit pattern 5a located on one end side of the row of one circuit pattern 5 is integrally formed with a power feeding pattern portion 5c. Similarly, the end located on one end side of the row of the other circuit pattern 5 The side circuit pattern 5a is integrally formed with a power feeding pattern portion 5d. The power supply pattern portions 5 c and 5 d are provided side by side at one end in the longitudinal direction of the reflective layer 31 and are separated from each other and insulated by the reflective layer 31. An electric wire (not shown) reaching the power source is individually connected to each of the power supply pattern portions 5c and 5d by soldering or the like. The circuit pattern 5 is formed by the procedure described below. First, a reflective layer 31 made of a prepreg impregnated with the uncured thermosetting resin is stuck on the device substrate 3, and then a copper foil of the same size is stuck on the reflective layer 31. Next, the laminated body thus obtained is heated and pressurized to cure the thermosetting resin, thereby pressing the device substrate 3 and the copper foil to the reflective layer 31 to complete the bonding. Next, after providing a resist layer on the copper foil and etching the copper foil, the remaining resist layer is removed to form the circuit pattern 5. The thickness of the circuit pattern 5 made of copper foil is, for example, 35 μm.

  Each semiconductor light emitting element 2 is formed of, for example, a double-wire type LED chip using a nitride semiconductor, and is formed by laminating a semiconductor light emitting layer 2a on one surface of a light-transmitting element substrate 2b. The element substrate 2b is made of, for example, a sapphire substrate. The element substrate 2b is thicker than the circuit pattern 5, for example, 90 μm. The semiconductor light emitting layer 2a is formed by sequentially stacking a buffer layer, an n-type semiconductor layer, a light emitting layer, a p-type cladding layer, and a p-type semiconductor layer on the main surface of the element substrate 2b. The light emitting layer has a quantum well structure in which barrier layers and well layers are alternately stacked. An n-side electrode is provided on the n-type semiconductor layer, and a p-side electrode is provided on the p-type semiconductor layer. This semiconductor light emitting layer 2a does not have a reflective film, and can emit light in both thickness directions.

  Each semiconductor light emitting element 2 is disposed between circuit patterns 5 adjacent to each other in the longitudinal direction of the device substrate 3, and is bonded to the same surface of the white reflective layer 31 by an adhesive layer 32. Specifically, the other surface parallel to one surface of the element substrate 2 b on which the semiconductor light emitting layer 2 a is laminated is bonded to the reflective layer 31 by the adhesive layer 32. By this adhesion, the circuit pattern 5 and the semiconductor light emitting element 2 are arranged in a straight line on the same surface of the reflective layer 31, so that the side surface of the semiconductor light emitting element 2 positioned in this arrangement direction and the circuit pattern 5 are close to each other. It is provided so as to face each other.

  The thickness of the adhesive layer 32 can be, for example, 5 μm or less. For the adhesive layer 32, for example, a translucent adhesive having a thickness of 5 μm or less and a light transmittance of 70% or more, for example, a silicone resin-based adhesive can be suitably used. The electrode of each semiconductor light emitting element 2 and the circuit pattern 5 arranged close to both sides of the semiconductor light emitting element 2 are connected by a bonding wire 6. Further, the end-side circuit patterns 5b located on the other end side of the two rows of circuit patterns 5 rows are also connected by bonding wires 6. Therefore, in this embodiment, each semiconductor light emitting element 2 is connected in series. The surface emitting source of the light emitting device 1 is formed by the device substrate 3, the reflective layer 31, the circuit pattern 5, each semiconductor light emitting element 2, the adhesive layer 32, and the bonding wire 6.

  The reflector 34 is not individually provided for each one or several semiconductor light emitting elements 2 but is a single one surrounding all the semiconductor light emitting elements 2 on the reflective layer 31. For example, as shown in FIG. Thus, it is formed with a rectangular frame, and the semiconductor light emitting element 2 is disposed in a recess 7 formed with the frame. The reflector 34 is bonded to the reflective layer 31, and a plurality of semiconductor light emitting elements 2 and circuit patterns 5 are housed therein, and the pair of power feeding pattern portions 5 c and 5 d are positioned outside the reflector 34. ing. The reflector 34 can be formed of, for example, a synthetic resin, and its inner peripheral surface is a reflective surface. The reflecting surface of the reflector 34 can be formed by vapor deposition or plating of a metal material having a high reflectance such as Al or Ni, or can be formed by applying a white paint having a high visible light reflectance. Alternatively, white powder can be mixed into the molding material of the reflector 34 to make the reflector 34 itself white with high visible light reflectivity. As the white powder, a white filler such as aluminum oxide, titanium oxide, magnesium oxide or barium sulfate can be used. In addition, it is desirable to form the reflecting surface of the reflector 34 so as to gradually open in the irradiation direction of the light emitting device 1.

  The phosphor-containing resin layer 9 is formed in the same manner as in the first embodiment. That is, fluorescence in which two or more kinds of phosphors having specific gravity similar to each other and different main wavelengths are dispersed in a transparent resin having a specific gravity of 20% or more of the phosphor having the largest specific gravity among these phosphors. A body-containing resin layer 9 is provided. And, such a phosphor-containing resin layer 9 is obtained by mixing a phosphor dispersion obtained by mixing and dispersing the two or more kinds of phosphors in a liquid transparent resin, using an injection device such as a dispenser, The surface of the reflective layer 31 and the semiconductor light emitting elements 2 and the bonding wires 6 arranged on the straight line are filled so as to be evenly filled, and then the thermosetting resin is cured.

  Also in the embodiment configured as described above, the dispersion state of the respective phosphor particles in the phosphor dispersion liquid becomes uniform, so that the variation in the emission color that occurs between the plurality of LED lamps 1 or in each part of one LED lamp 1. Can be reduced.

  Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1
Three types of phosphors having very similar specific gravity (difference of 0.2 or less) were mixed with a silicone resin having a specific gravity of 20% or more of the specific gravity of the phosphor having the largest specific gravity to prepare a phosphor dispersion. . Then, using this phosphor dispersion liquid, three samples of LED lamps having the configuration shown in FIG. 1 were produced, and the variation in color tone in the vicinity of a color temperature of 5000K was examined.

  That is, a green phosphor having a dominant wavelength (peak wavelength) of 535 nm and a specific gravity of 4.8 (particle shape is spherical and D50 is 12 μm), and a yellow phosphor having a peak wavelength of 570 nm and a specific gravity of 4.9 (particle shape is A red phosphor having a spherical shape with a D50 of 11 μm and a peak wavelength of 615 nm and a specific gravity of 4.7 (particle shape is spherical and D50 is 15 μm) was mixed and dispersed in a silicone resin having a specific gravity of 1. The blending ratio of the green phosphor, the yellow phosphor and the red phosphor was 4.4% by weight, 2.6% by weight and 2.0% by weight with respect to the silicone resin, respectively.

  Next, the silicone resin liquid containing the three types of phosphors thus obtained was placed in a cup (concave portion) having a depth of 1.0 mm and an opening diameter of 3 mm where an LED chip emitting blue light having a wavelength of 460 nm was disposed. After applying and filling with a dispenser, the silicone resin was cured, and three LED lamps having the configuration shown in FIG. 1 were produced. It took about 30 minutes to produce the three samples. Moreover, the average particle diameter (D50) of each phosphor is a value measured by a laser diffraction particle size distribution measuring device HOLIBA LA-300 (manufactured by Horiba, Ltd.). Furthermore, the variation in chromaticity x, y of light emission from the blue LED chip was set to 0.0001 or less between samples.

Example 2
Although the specific gravity difference between the phosphors is larger than that in Example 1, three types of phosphors having a sufficiently close specific gravity (specific gravity difference is 2 or less) are 20% of the specific gravity of the phosphor having the largest specific gravity. A phosphor dispersion liquid was prepared by mixing with a silicone resin having the above specific gravity. That is, a green phosphor having a peak wavelength of 525 nm and a specific gravity of 4 (particles are needle-like and D50 is 7 μm), and a yellow phosphor having a peak wavelength of 562 nm and a specific gravity of 5.0 (particle shape is spherical and D50 is 15 μm) And a red phosphor having a peak wavelength of 650 nm and a specific gravity of 3 (particle shape is spherical and D50 is 8 μm) were mixed and dispersed in a silicone resin having a specific gravity of 1, respectively.

  Next, using the silicone resin liquid containing the three kinds of phosphors thus obtained, three samples of LED lamps having the configuration shown in FIG.

  Next, the LED lamps obtained in Example 1 and Example 2 were each made to emit light, and the emission spectrum was measured with an instantaneous spectrophotometer MCPD-7000 (manufactured by Otsuka Electronics Co., Ltd.). Then, chromaticity and color temperature were calculated for each sample from the obtained emission spectrum. Also, the value of duv was obtained. These measurement results are shown in Table 1 and FIG. 6 (chromaticity coordinates thereof). Here, duv represents the color shift of light emission (white light) from the light emitting device as a deviation from the locus of black body radiation in the chromaticity diagram.

  As is apparent from Table 1 and FIG. 6, the LED lamps obtained in Example 1 and Example 2 have little color tone variation between samples near a color temperature of 5000 K, and the time elapsed after preparation of the phosphor dispersion liquid. It can be seen that the variation in emission color due to is reduced. In particular, in the LED lamp of Example 1, three types of particles having extremely similar specific gravity (difference in specific gravity of 0.2 or less) and having an average particle diameter (D50) approximated by the same spherical particle shape. Since the phosphor is used, there is almost no variation in color tone between the samples, and the variation in emission color over time after preparation of the phosphor dispersion is further eliminated than the LED lamp of Example 2. Recognize.

It is sectional drawing which shows schematically the structure of the LED lamp which is 1st Embodiment of the light-emitting device of this invention. It is a top view which shows an example of the LED module which has arrange | positioned two or more LED lamps shown in FIG. It is the III-III sectional view taken on the line of FIG. It is a top view which shows the LED lamp which is 2nd Embodiment of the light-emitting device of this invention. It is the FF sectional view taken on the line of FIG. It is a chromaticity diagram which shows the chromaticity of light emission of each sample of the LED lamp obtained in Example 1 and Example 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... LED lamp, 2 ... LED chip, 3 ... Board | substrate, 4 ... Electrical insulation layer, 5 ... Circuit pattern, 6 ... Bonding wire, 7 ... Recessed part, 8 ... Frame, 9 ... Phosphor containing resin layer.

Claims (2)

A light emitting element;
A layer formed on the light-emitting element, each of which includes two or more phosphors that emit visible light having different main wavelengths when excited by light emitted from the transparent resin and the light-emitting element. The above phosphor has an approximate specific gravity, and the transparent resin has a specific gravity of 20% or more of the specific gravity of the phosphor having the largest specific gravity among the phosphors; and a phosphor-containing resin layer;
A light-emitting device comprising:   The light emitting device according to claim 1, wherein a difference in specific gravity between the two or more kinds of phosphors is 2 or less.

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