JP2008244469A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of improving light emitting efficiency at various color temperatures specifically at a color temperature in a range of 2,850K to 3,000K corresponding to an electric bulb. <P>SOLUTION: The light emitting device includes a light emitting element and a fluorescent material layer for emitting light exited by blue light emitted from the light emitting element. The fluorescent material layer comprises a green fluorescent material for emitting light having a light emission peak in a range of a wave length of 520 nm to 540 nm, one or two kinds of yellow fluorescent materials for emitting light having a light emission peak at a wave length in a range not smaller than 565 nm and not larger than 585 nm, and a red fluorescent material for emitting light having a light emission peak at a wave length in a range not smaller than 600 nm. The light emitting device emits white light having a color temperature in a range of 2,850K to 3,000K by the color mixing of the blue light and the light from the fluorescent material layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  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 and high reliability, and low power consumption, impact resistance, high purity display color, lightness, thinness, and other features. Application of 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. Of these, the method (2) is generally widely used. And as a structure of the LED lamp to which the above-mentioned method (2) is applied, a transparent resin mixed with a phosphor is poured into a cup-shaped frame equipped with an LED chip, and this is solidified to contain the phosphor. A structure in which a resin layer is formed is common (see, for example, Patent Document 1). In addition to the above-mentioned bullet-type LED elements and SMD (Surface Mounting Device) type, a chip-on-board (COB) with multiple chips mounted on a substrate (board) has been developed for the purpose of increasing brightness. Has been. The characteristics required for general illumination include color rendering as an index of color appearance, in particular average color rendering index Ra, in addition to high efficiency (light emission efficiency) as an LED lamp. For this color rendering property, lineups such as Ra 80 to 85 and Ra 90 or higher which are similar to fluorescent lamps are required.

  Color rendering is an evaluation of the color appearance of a light source using illumination 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. It is expressed as an average value of 1 to 8 color rendering evaluation values. The special color rendering index Ri is the test No. Expressed as individual special color rendering evaluation values of 9 to 15. The color rendering index Ra is an index indicating whether the color of the white light source that is the reference light source is faithfully reproduced. As a rule, the color rendering index Ra is better as it is closer to 100.

  In general, a so-called high color rendering type LED lamp having a high average color rendering index Ra has a yellow emission from a yellow phosphor such as YAG that emits light having a wavelength of 560 nm to 570 nm by a blue emission from an LED chip, and a wavelength of 620 nm. The white light with excellent color rendering properties is synthesized by the red light emitted from the red light emitter that emits the light. In order to increase the average color rendering index Ra, it is usual to use a red phosphor that emits red light as described above. However, in recent years, the system is configured by adding a green phosphor to this system.

In addition, regarding the light color, that is, the color temperature, a lineup of various color temperatures from 6700K to 2850K is required in consideration of HID lamps, light bulbs, and fluorescent lamps. Among the various color temperatures, the color temperature corresponding to the light bulb color, especially 2850K to 3000K, is greatly reduced in luminous efficiency because the peak wavelength of light emission is far from 555 nm where the relative luminous sensitivity is the best. Accordingly, there is a demand for improvement in light emission efficiency, particularly at 2850K to 3000K, which is a color temperature corresponding to a light bulb color.
JP 2001-148516 A

  The present invention has been made to solve such problems, and provides a light emitting device capable of improving the light emission efficiency at each color temperature, particularly from 2850 K to 3000 K, which is a color temperature corresponding to a light bulb color. Intended

  The light-emitting device according to claim 1 is a light-emitting element that emits blue light; and green fluorescence that emits light having an emission peak in a wavelength range of 520 nm or more and less than 540 nm when excited by the blue light emitted from the light-emitting element. And one or more yellow phosphors that emit light having an emission peak in the wavelength range of 565 nm to less than 585 nm, and a red phosphor that emits light having an emission peak in the wavelength range of 600 nm and more And emitting white light having a color temperature of 2850 to 3000 K by color mixture of the blue light and light emitted from the phosphor layer.

  The light emitting device according to claim 2 emits white light having an average color rendering index Ra of 80 or more due to color mixture of the blue light and light emitted from the phosphor layer in the light emitting device according to claim 1. It is characterized by that.

  Furthermore, the light emitting device according to claim 3 is characterized in that, in the light emitting device according to claim 1, in the yellow phosphor, a half width of an emission peak in a wavelength range of 565 nm to less than 585 nm is 100 nm or more. .

  In the above-described inventions according to claims 1 to 3, the definitions and technical meanings of terms are as follows unless otherwise specified. A light emitting element that emits blue light emits blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm), and excites a phosphor with the emitted blue light to emit visible light. Examples of the light emitting element that emits blue light used in the present invention include, but are not limited to, a blue light emitting type LED chip.

  The phosphor is excited by blue light emitted from such a light emitting element to emit visible light, and a desired emission color as a light emitting device is obtained by mixing the visible light and the blue light emitted from the light emitting element. To get. In the present invention, the phosphor includes a green phosphor that emits light having an emission intensity peak (hereinafter referred to as “emission peak”) in a wavelength range of 520 nm or more and less than 540 nm, and a wavelength range of 565 nm or more and less than 585 nm. Mixing three or more phosphors in total, one or two or more yellow phosphors that emit light having an emission peak and a red phosphor that emits light having an emission peak in the wavelength range of 600 nm or more. Can be used. That is, a green phosphor having a dominant wavelength (peak wavelength) in the range of 520 nm to less than 540 nm, one or more yellow phosphors having a dominant wavelength in the range of 565 nm to less than 585 nm, and a red having a dominant wavelength in the range of 600 nm or more. A phosphor mixed with a phosphor can be used. In this case, the types and blending ratios of these three or more phosphors are such that high light emission efficiency can be obtained while maintaining high color rendering properties so that high light emission efficiency can be obtained for light emission from the light emitting device. Adjusted to

  From the light emitting device of the present invention, light emission suitable for lighting with a light bulb color can be obtained at a color temperature of 2850 to 3000 K by mixing colors of the blue light and the light emission from the phosphor layer. In particular, it is preferable that the color temperature of light emission is 2850 to 3000 K and the average color rendering index is 80 or more because it is suitable for lighting with a light bulb color. In the yellow phosphor, the half-value width of the emission peak in the wavelength range of 565 nm to less than 585 nm is preferably 100 nm or more, and the average color rendering index obtained from the light emitting device is more than 80. preferable. The half width is more preferably 120 nm to 130 nm. When the half width is less than 100 nm, a high average color rendering index cannot be obtained. In addition, when the full width at half maximum is too large, the light emission efficiency decreases, which is not preferable. Note that the half-width at the emission peak of the phosphor refers to the spectrum spread width (wavelength) at half the intensity of the emission peak. When this yellow phosphor is used in a single color, it becomes white at a color temperature of 4200K to 3500K.

  One or more yellow phosphors having an emission peak in the wavelength range of 565 nm to less than 585 nm, a green phosphor having an emission peak in the wavelength range of 520 nm to less than 540 nm, and a wavelength of 600 nm or more By mixing and using three or more phosphors of red phosphors having an emission peak, the energy conversion efficiency is high, so even if the color temperature is reduced from 5000K to 3000K, the decrease in emission efficiency is suppressed. Luminous efficiency can be improved at each color temperature, particularly from 2850K to 3000K, which is a color temperature corresponding to a light bulb color.

  The phosphor layer containing the phosphor is formed as a layer obtained by mixing and dispersing the above-described phosphor, for example, three kinds of phosphors in addition to a transparent resin such as a silicone resin or an epoxy resin. Although it can be formed so as to cover the outside of the light-emitting element, it is also possible to form a transparent resin layer so as to directly cover the light-emitting element and to provide a layer containing the above-described phosphor thereon.

  According to the light emitting device of claim 1, the emission spectrum from the phosphor has a light emission peak in the wavelength range of 520 nm or more and less than 540 nm, a light emission peak in the wavelength range of 600 nm or more, and a wavelength range of 565 nm or more and less than 585 nm. Since it has a light emission peak, the energy conversion efficiency is high, so that the light emission efficiency at each color temperature, particularly from 2850 K to 3000 K, which is the color temperature corresponding to the light bulb color, can be improved.

  According to the light emitting device of the second aspect, a high average color rendering index can be achieved when the color temperature corresponding to the light bulb color is 2850 to 3000K.

  According to the light emitting device of the third aspect, since the energy conversion efficiency can be further increased, it is possible to further improve the light emission efficiency at each color temperature, particularly from 2850 K to 3000 K, which is a color temperature corresponding to a light bulb color.

  Therefore, according to the present invention, it is possible to further improve the light emission efficiency at 2850 K to 3000 K, which is a color temperature corresponding to a light bulb color, in comparison with the conventional color temperature. Further, since the energy conversion efficiency can be further increased, the light emission efficiency can be increased while maintaining high color rendering properties. Therefore, for the light color, that is, the color temperature, in the specifications of various average color rendering index Ra, A lineup of color temperatures can be prepared.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an embodiment in which the light emitting device of the present invention is applied to an LED, and FIG. 2 is a diagram of a plurality of LED lamps shown in FIG. FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 2.

  The LED lamp 1 shown in FIG. 1 has a blue light emitting type LED chip 2 as a light emitting element. The LED chip 2 is mounted on a substrate 4 having a circuit pattern 3. As the substrate 4, a flat plate made of aluminum (Al), nickel (Ni), glass epoxy resin or the like having heat dissipation and rigidity is used, and a cathode side and an anode side are disposed on the substrate 4 through an electric insulating layer 5. Circuit patterns 3 are respectively formed. The circuit pattern 3 is made of an alloy of Cu and Ni, Au, or the like.

  The bottom electrode of the LED chip 2 is disposed on and electrically connected to the circuit pattern 3 on one electrode side, and the bonding electrode 6 such as a gold wire is connected to the circuit pattern 3 on the other electrode side. It is electrically connected via. As an electrode connection structure of the LED chip 2, a flip chip connection structure can also be applied. According to these electrode connection structures, the light extraction efficiency to the front surface of the LED chip 2 is improved.

  On the substrate 4, a frame 8 made of resin or the like having a recess 7 is provided. The frame 8 having the recess 7 is made of a synthetic resin such as PBT (polybutylene terephthalate), PPA (polyphthalamide), PC (polycarbonate), etc., and the LED chip 2 is disposed and accommodated in the recess 7. . And in the recessed part 7 in which LED chip 2 was accommodated, the green fluorescent substance which has a light emission peak in the wavelength range of 520 nm or more and less than 540 nm, and the 1 type or 2 or more types which have a light emission peak in the wavelength range of 565 nm or more and 585 nm A phosphor-containing resin in which a total of three or more (for example, three) phosphors, a yellow phosphor and a red phosphor that emits light having an emission peak in a wavelength range of 600 nm or more, are mixed and dispersed in a transparent resin. The LED chip 2 is covered with such a phosphor-containing resin layer 9. As the transparent resin, for example, a silicone resin or an epoxy resin is used.

The green phosphor is, for example, a YAG phosphor such as RE ₃ (Al, Ga) ₅ O ₁₂ : Ce phosphor (RE represents at least one selected from Y, G and La), AE ₂ SiO ₄ : Eu phosphors (AE represents alkaline earth elements such as Sr, Ba, Ca) and silicate phosphors such as Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce phosphors, sialon phosphors (for example, Ca _x Si _y Al _z ON: Eu ²⁺ ), Ca ₃ Sc ₂ O ₄ : Ce phosphor and the like.

Examples of the red phosphor include oxysulfide phosphors such as La ₂ O ₂ S: Eu phosphor, nitride phosphors (for example, AE ₂ Si ₅ N ₈ : Eu ²⁺ and CaAlSiN ₃ : Eu ²⁺ ), and the like. Although used, it is not particularly limited.

The yellow phosphor is, for example, a YAG phosphor such as RE ₃ (Al, Ga) ₅ O ₁₂ : Ce phosphor (RE represents at least one selected from Y, Gd and La), (Tb, Al ) ₅ O ₁₂ : TAG phosphor such as Ce phosphor, sialon-based phosphor (for example, Ca _X Si _Y Al _Z ON: Eu ²⁺ ), AE ₂ SiO ₄ : Eu phosphor (AE is Sr, Ba, Ca Selected from the silicate phosphors such as Sr ₃ Si ₃ O ₅ : Eu ²⁺ phosphors and the like according to the characteristics and applications of the phosphors. In addition, one type or two or more types of yellow phosphors can be used. When two or more types of yellow phosphors are used, the emission peak of the yellow phosphor refers to an emission peak obtained by mixing each type of yellow phosphor.

  In the LED lamp 1 of the embodiment, the applied electrical energy is converted and emitted by the LED chip 2 into blue light having a dominant wavelength of 420 to 480 nm (for example, 460 nm), and the emitted blue light is emitted from the phosphor-containing resin layer. 9 is a phosphor composed of a total of three or more types (for example, three types) of a green phosphor, a red phosphor, and one or more yellow phosphors, and is 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 of the embodiment, the emission spectrum from the phosphor has a wavelength in the range of 565 nm to less than 585 nm, together with a light emission peak in the green range having a wavelength of 520 nm or more and less than 540 nm and a light emission peak in the red range of wavelength 600 nm or more. Since it has a light emission peak in the yellow range, the energy conversion efficiency is high, so that the light emission efficiency can be improved. In particular, the light emission efficiency can be improved at a color temperature of 3000 to 2850 K corresponding to the light bulb color.

  In the above embodiment, the LED module 21 in which a plurality of LED lamps 1 are arranged in a matrix has been described. However, the present invention is not limited to this, and for example, a plurality of LED lamps 1 are arranged in a row. The LED lamps 1 may be formed in a single arrangement.

  4 and 5 show a light-emitting device for forming an LED package according to the second embodiment of the present invention. FIG. 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 reference numerals are used for the same components as those in the drawings relating to the first embodiment, and the description thereof is simplified or omitted.

  A light emitting device (LED lamp) 1 shown in FIGS. 4 and 5 includes a package substrate, for example, a device substrate 4, a reflective layer 31, a circuit pattern 3, a plurality of semiconductor light emitting elements (for example, blue LED chips), and a plurality of semiconductor light emitting devices. The adhesive layer 32, the reflector 34, the phosphor-containing resin layer 9, and the light diffusion member 33 are formed. The phosphor-containing resin layer 9 also functions as a sealing member. The device substrate 4 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 4 is made of a synthetic resin, it can be formed of, for example, an epoxy resin containing glass powder. When the device substrate 4 is made of metal, the heat radiation from the back surface of the device substrate 4 is improved, the temperature of each part of the device substrate 4 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 4. 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 4 by its own adhesiveness.

  The circuit pattern 3 is bonded to a surface of the reflective layer 31 opposite to the surface to which the device substrate 4 is bonded as an energizing element for each semiconductor light emitting element 2. The circuit pattern 3 is formed in two rows dotted at predetermined intervals in the longitudinal direction of the device substrate 4 and the reflective layer 31 in order to connect the semiconductor light emitting elements 2 in series, for example. The end-side circuit pattern 3a located on one end side of the row of one circuit pattern 3 is integrally formed with a power feeding pattern portion 3c. Similarly, the end located on one end side of the row of the other circuit pattern 3 The side circuit pattern 3a is integrally formed with a power feeding pattern portion 3d. The power feeding pattern portions 3 c and 3 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 3c and 3d by soldering or the like.

  The circuit pattern 3 is formed by the procedure described below. First, a reflective layer 31 made of a prepreg impregnated with the uncured thermosetting resin is pasted on the device substrate 4, and then a copper foil of the same size is pasted on the reflective layer 31. Next, the laminated body thus obtained is heated and pressurized to cure the thermosetting resin, whereby the device substrate 4 and the copper foil are pressed against the reflective layer 31 to complete the adhesion. 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 3. The thickness of the circuit pattern 3 made of copper foil is, for example, 35 μm.

  As shown in FIG. 5, the semiconductor light emitting device 2 is formed of a double wire type LED chip using, for example, a nitride semiconductor, and is formed by laminating a semiconductor light emitting layer 2a on one surface of a light transmitting element substrate 2b. ing. The element substrate 2b is made of, for example, a sapphire substrate. The element substrate 2b is thicker than the circuit pattern 3, 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 3 adjacent to each other in the longitudinal direction of the device substrate 4, 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 3 and the semiconductor light emitting element 2 are arranged in a straight line on the same surface of the reflective layer 31. Therefore, the side surface of the semiconductor light emitting element 2 positioned in this arrangement direction and the circuit pattern 3 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.

  As shown in FIGS. 4 and 5, the electrode of each semiconductor light emitting element 2 and the circuit pattern 3 disposed in proximity to both sides of the semiconductor light emitting element 2 are connected by bonding wires 6. Further, the end-side circuit patterns 3b positioned on the other end side of the two rows of circuit patterns 3 rows are also connected by bonding wires 6. Therefore, in this embodiment, each semiconductor light emitting element 2 is connected in series. The surface light source of the light emitting device 1 is formed by the device substrate 4, the reflective layer 31, the circuit pattern 3, 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 that surrounds all the semiconductor light emitting elements 2 on the reflective layer 31, and has a rectangular frame, for example. Thus, the semiconductor light emitting element 2 is disposed in the recess 7 formed by the frame. The reflector 34 is bonded to the reflective layer 31, and a plurality of semiconductor light emitting elements 2 and circuit patterns 3 are housed therein, and the pair of power feeding pattern portions 3 c and 3 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 said white powder, white fillers, such as aluminum oxide, titanium oxide, magnesium oxide, 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.

  Similarly to the first embodiment, the phosphor-containing resin layer 9 is formed by aligning the surface of the reflective layer 31 with a liquid thermosetting resin in which, for example, three kinds of phosphors are mixed using an injection device such as a dispenser. The semiconductor light-emitting elements 2 and the bonding wires 6 and the like arranged in the above are filled so as to be evenly filled, and the thermosetting resin is cured by heating.

  The liquid transparent resin that flows between the surface of the reflective layer 31 and the bonding wire 6 reaches each semiconductor light emitting element 2 and the bonding wire 6 due to a capillary phenomenon or the like, and the film thickness thereof is almost uniform. The body is also almost uniformly dispersed in the transparent resin. The second embodiment configured in this way also has the same effect as that of the first embodiment, and can emit light substantially uniformly.

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

Example 1 and Comparative Example 1
In Example 1, a green phosphor (oxide phosphor) having an emission peak at a wavelength of 520 nm, a red phosphor (nitride phosphor) having an emission peak at a wavelength of 620 nm, and an emission peak at a wavelength of 575 nm. Yellow phosphors (oxide-based phosphors) having a half-value width of 130 nm were mixed and dispersed in the silicone resin at a blending ratio shown in Table 1 (blending ratio with respect to the silicone resin: wt%). In Comparative Example 1, a yellow phosphor having an emission peak at a wavelength of 560 nm having a half width of 100 nm (oxide-based phosphor) is used, and this yellow phosphor and a green phosphor having an emission peak at a wavelength of 520 nm ( The oxide phosphor) and the red phosphor (nitride phosphor) having an emission peak at a wavelength of 620 nm were mixed and dispersed in the silicone resin at the blending ratios shown in Table 1, respectively. Furthermore, as a reference example, the above-described green phosphor (oxide-based phosphor) having an emission peak at a wavelength of 520 nm, and a yellow phosphor (oxide-based phosphor) having an emission peak at a wavelength of 575 nm and a half width of 130 nm, Were mixed and dispersed in the silicone resin at the blending ratio shown in Table 1 (blending ratio with respect to the silicone resin; wt%).

  Next, after filling the phosphor-containing silicone resin thus obtained in the recess 8 having an opening diameter of 3 mm, the silicone resin is cured to form a phosphor-containing resin layer, and the LED lamp having the configuration shown in FIG. 1 was created. The optical path length of the phosphor-containing resin layer 9 was 1.0 mm. The optical path length refers to the thickness of the phosphor-containing resin layer on the light extraction side from the upper surface of the LED chip.

  Thus, the LED lamps obtained in Example 1, Comparative Example 1, and Reference Example were caused to emit light, and the color temperature of light emission, the average color rendering index Ra, and the light emission efficiency were measured. The color temperature and the average color rendering index Ra are measured using a spectrophotometer (instant spectrophotometer MCPD-7000 manufactured by Otsuka Electronics), and the luminous efficiency is measured using a goniometer (GMT-1 manufactured by Fuji Photoelectric Industry Co., Ltd.). It was measured. These measurement results are shown in Table 1.

Comparative Examples 2 and 3
In Comparative Example 2 and Comparative Example 3, in order to obtain a high average color rendering index Ra at a color temperature of 5000K, a green phosphor having a light emission peak at a wavelength of 520 nm and a light emission peak at a wavelength of 620 nm with respect to Comparative Example 1. The compounding ratio of the red phosphor was increased, and the compounding ratio of the yellow phosphor having an emission peak (half width 100 nm) at a wavelength of 560 nm was decreased. Each of these phosphors was blended in the silicone resin, and mixed and dispersed at the blending ratio shown in Table 1 (blending ratio with respect to the silicone resin: wt%). Next, the phosphor-containing silicone resin thus obtained was filled in the recess 8 having an opening diameter of 3 mm, as in Example 1 and Comparative Example 1, and then the silicone resin was cured to form the phosphor-containing resin layer 9. An LED lamp 1 having the structure shown in FIG. 1 was formed.

  Thus, the LED lamps obtained in Comparative Examples 2 and 3 were caused to emit light, and the color temperature of light emission, the average color rendering index Ra, and the light emission efficiency were measured in the same manner as in Example 1. These measurement results are shown in Table 1. The luminous efficiency is a relative value when the luminous efficiency of the LED lamp of the reference example is 100%. Also, the luminous efficiencies were calculated for Example 1 and Comparative Examples 1 to 3 where the luminous efficiency at the color temperature of 5000 K and the average color rendering index Ra74 of the reference example was 1 (reference value). FIG. 6 shows the relationship between the average color rendering index Ra thus obtained and the luminous efficiency (relative value).

  The following can be understood from Table 1 and FIG. The luminous efficiency and average color rendering index Ra of Example 1 are higher than those of Comparative Examples 1 to 3, but the average color rendering index Ra is low. In general, the luminous efficiency and the average color rendering index Ra are correlated with each other, and the luminous efficiency decreases as the average color rendering index Ra is increased. As can be seen from FIG. 6, by adjusting the blending ratio (weight ratio) of the various phosphors used in Example 1, there is a slight decrease in the light emission efficiency. In the same high average color rendering index Ra as in Examples 1 to 3, a high luminous efficiency equal to or higher than that in Comparative Examples 1 to 3 can be obtained.

Examples 2-6, Comparative Examples 4-6
In Example 2, in order to obtain high luminous efficiency at a color temperature of 3000 (K), as shown in Table 1, with respect to Example 1, the blending ratio of the green phosphor having a light emission peak at a wavelength of 520 nm is set. While decreasing, it was used by increasing the blending ratio of the yellow phosphor having a half-value width of 130 nm and an emission peak at a wavelength of 575 nm. Further, in Examples 3 and 4, in order to obtain high luminous efficiency and average color rendering index Ra at a color temperature of 3000 (K), as shown in Table 1, light was emitted at a wavelength of 520 nm as compared to Example 1. The green phosphor having a peak, the red phosphor having an emission peak at a wavelength of 620 nm, and the yellow phosphor having an emission peak at a wavelength of 575 nm at a half-value width of 130 nm were used in an increased ratio. Further, in Comparative Examples 4 to 6, the compounding ratio of the green phosphor having an emission peak at a wavelength of 520 nm and the red phosphor having an emission peak at a wavelength of 620 nm is increased with respect to Comparative Example 1, and the emission peak at a wavelength of 560 nm. Various blending ratios of yellow phosphors having a (half-value width of 100 nm) were used.

  Furthermore, in Examples 5 and 6, as shown in Table 1, in addition to the green phosphor having an emission peak at a wavelength of 520 nm and the red phosphor having an emission peak at a wavelength of 620 nm, the half-value width is 85 nm and the wavelength is 540 nm. Obtained by mixing two kinds of a yellow phosphor having an emission peak (oxide-based phosphor) and a yellow phosphor having a half width of 75 nm and having an emission peak at a wavelength of 595 nm (oxide-based phosphor). A yellow phosphor having an emission peak at a wavelength of 575 nm and a half width of 120 nm was blended. Each of these phosphors was blended in the silicone resin, and mixed and dispersed at the blending ratio shown in Table 1 (blending ratio with respect to the silicone resin: wt%).

  Next, the phosphor-containing silicone resin thus obtained was filled in the recess 8 having an opening diameter of 3 mm, as in Example 1, and then the silicone resin was cured to form the phosphor-containing resin layer 9. An LED lamp 1 having the configuration shown in FIG.

  Thus, the LED lamps obtained in Examples 2 to 6 and Comparative Examples 4 to 6 were caused to emit light, and the color temperature of light emission, the average color rendering index Ra, and the light emission efficiency were measured in the same manner as in Example 1. These measurement results are shown in Table 1. The luminous efficiency is a relative value when the luminous efficiency of the LED lamp of the reference example in Table 1 is 100%. For Examples 2 to 4, Examples 5 and 6, and Comparative Examples 4 to 6 using the same type of phosphor, the light emission efficiency at the average color rendering index Ra74 and the color temperature of 5000 K in the reference example is 1 (reference value). ), The graph showing the luminous efficiency (relative value) with respect to the average color rendering index Ra is shown in FIG.

Examples 7-9
A green phosphor (oxide-based phosphor) having an emission peak at a wavelength of 520 nm, a red phosphor (nitride-based phosphor) having an emission peak at a wavelength of 620 nm, and a half-value width having an emission peak at a wavelength of 565 nm is 120 nm The yellow phosphor (YAG phosphor) was mixed and dispersed in the silicone resin at the blending ratio shown in Table 1 (blending ratio with respect to the silicone resin: wt%). Next, after filling the phosphor-containing silicone resin thus obtained in the recess 8 having an opening diameter of 3 mm, the silicone resin is cured to form a phosphor-containing resin layer, and the LED lamp having the configuration shown in FIG. 1 was created. The optical path length of the phosphor-containing resin layer 9 was 1.0 mm.

  Thus, the LED lamps obtained in Examples 7 to 9 were caused to emit light, and the color temperature of light emission, the average color rendering index Ra, and the light emission efficiency were measured. These measurement results are shown in Table 1.

  From the results shown in Table 1 and FIG. That is, in Comparative Examples 4 to 6, the average color rendering index Ra is about the same, and the luminous efficiency ratio between LED lamps having a color temperature different from 3000K and 5000K (emission efficiency of 3000K / emission efficiency of 5000K) is about 80%. On the other hand, in Examples 2 to 4, the same luminous efficiency ratio is about 95 to 100%, and almost no reduction is observed. Further, by comparing Examples 2 to 4 and Comparative Examples 4 to 6, even a yellow phosphor having a light emission peak at the same wavelength of 575 nm can obtain higher luminous efficiency with a yellow phosphor having a wider half-value width. Was confirmed. In addition, white light having higher luminous efficiency can be obtained by further using a yellow phosphor (oxide phosphor) having a light emission peak in the vicinity of a wavelength of 555 nm with a good specific visibility.

  Further, yellow fluorescence having a light emission peak at a wavelength of 575 nm (half-value width 130 nm) by comparing the light emission characteristics of the LED lamps obtained in Examples 7 to 9 with the light emission characteristics of the LED lamps obtained in Examples 2 to 4. By using a yellow phosphor having a light emission peak (half-value width 120 nm) at a wavelength of 565 nm instead of the body, the average color rendering index Ra may slightly decrease at 3000 K, which is the color temperature corresponding to the light bulb color. However, it turns out that the LED lamp which has higher luminous efficiency is obtained.

  Therefore, a green phosphor having an emission peak in a wavelength range of 520 nm or more and less than 540 nm, one or more yellow phosphors having an emission peak in a wavelength range of 565 nm or more and less than 585 nm, and a wavelength of 600 nm or more. When a red phosphor having a light emission peak is used, high luminous efficiency is obtained while maintaining high color rendering properties at a color temperature, particularly from 2850 K to 3000 K, which is a color temperature corresponding to a light bulb color. It can be seen that an LED lamp can be obtained. In addition, since an LED lamp capable of obtaining high luminous efficiency while maintaining high color rendering properties at a color temperature in the vicinity of 2850 K to 3000 K can be obtained, various color temperatures, for example, a range from daylight color to light bulb color, 6700K. It can be seen that an LED lamp having a high average color rendering index Ra and a high luminous efficiency can be obtained even at a color temperature such as 5000K, 4200K, and 3000K.

It is sectional drawing which shows the structure of 1st Embodiment which applied the light-emitting device of this invention to the LED lamp. 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. FIG. 3 is a cross-sectional view taken along line AA ′ in FIG. 2. It is a top view of the light-emitting device concerning 2nd Embodiment of the light-emitting device of this invention. FIG. 5 is a cross-sectional view taken along line FF ′ in FIG. 4. It is a graph which shows the relationship between average color rendering evaluation number Ra and luminous efficiency (relative value).

Explanation of symbols

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

Claims (3)

A light emitting device emitting blue light;
A green phosphor that emits light having a light emission peak in a wavelength range from 520 nm to less than 540 nm and excited to emit light having a light emission peak in a wavelength range from 565 nm to less than 585 nm. Phosphor layers each containing one or two or more yellow phosphors and a red phosphor that emits light having an emission peak in a wavelength range of 600 nm or more,
A light-emitting device that emits white light having a color temperature of 2850 to 3000 K by mixing colors of the blue light and light emitted from the phosphor layer.   2. The light emitting device according to claim 1, wherein white light having an average color rendering index Ra of 80 or more is emitted by mixing colors of the blue light and light emitted from the phosphor layer.   2. The light emitting device according to claim 1, wherein in the yellow phosphor, a half width of an emission peak in a wavelength range of 565 nm to less than 585 nm is 100 nm or more.

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