White light-emitting device

Abstract

To provide a white light-emitting device having a high flux and capable of easy high color rendering.SOLUTION: A white light-emitting device includes a semiconductor light-emitting element and a first fluorescent substance, in which a general color rendering index Ra and a special color rendering index Ri satisfy 90 or more. The first fluorescent substance emits visible light by being excited by at least one of first blue light SS having a first peak with a peak wavelength P1 and second blue light LL having a second peak with a peak wavelength P2 in the wavelength range of 430 to 480 nm of the emission spectrum. The white light-emitting device emits white light by the first and second blue light and the visible light. P1 and P2 satisfy 430nm≤P1<P2≤480nm and P2-P1≥16nm. When the emission intensities of the first peak, the second peak, and a valley between the first and second peaks are Ip1, Ip2, and Iv, respectively, the following inequality is satisfied: 0.5≤(Ip1 / Ip2)≤2 and 0.3≤Iv / {(Ip1+Ip2) / 2}≤0.5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a white light emitting device. [Background technology]

[0002] Light-emitting devices using light-emitting elements such as light-emitting diodes (LEDs) and phosphors excited by the light-emitting elements have been put to practical use. In LED lighting equipment, the continuous spectrum that is desired to be expressed is realized by combining the emission spectra of the light emitted from the light-emitting elements and phosphors. For example, by raising the average color rendering index Ra (average of R1 to R8) and the specific color rendering index Ri (i=9 to 15) to, for example, 90 or higher, the continuous spectrum of sunlight defined by the International Commission on Illumination (CIE) can be approximately expressed by the emitted light of the LED and phosphors.

[0003] A method has been proposed in the past in which green and red phosphors are excited by two blue LEDs with different wavelengths to obtain white light with high color rendering (see, for example, Patent Document 1). The white light emitting device described in Patent Document 1 includes a first blue LED that emits blue light having a first peak at a peak wavelength P1 and a second blue LED that emits blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum. Such a white light emitting device obtains white light L with high color rendering by exciting the second phosphor with these two blue LEDs with different wavelengths. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-219519 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, it is considered desirable for the spectrum waveform of high color rendering light to be broad and close to that of sunlight. However, the light emitted by a white light emitting device that combines a semiconductor light emitting element and a phosphor has a trade-off between the color rendering indexes R9 (red) and R12 (blue), and there has been a problem in that it is difficult to achieve a color rendering index of 90 or more for R9 (red) and R12 (blue).

[0006] The present invention has been made to solve the above problems, and has an object to provide a white light emitting device that has high luminous flux and easily achieves high color rendering. [Means for solving the problem]

[0007] The present invention has been made in order to achieve the above object, and provides a white light emitting device including at least a semiconductor light emitting element and a first phosphor, the first phosphor is excited by at least one of a first blue light having a first peak at a peak wavelength P1 and a second blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum to emit visible light; the white light emitting device emits white light by the first blue light, the second blue light, and the visible light; The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensity at the first peak is Ip1, the emission intensity at the second peak is Ip2, and the emission intensity at a valley between the first peak and the second peak is Iv, 0.5≦(Ip1 / Ip2)≦2 (3) 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ··· (4) Fulfilling Provided is a white light emitting device that satisfies an average color rendering index Ra and a specific color rendering index Ri of 90 or more.

[0008] According to such a white light emitting device, it is easy to obtain a white light emitting device with high luminous flux and high color rendering.

[0009] At this time, the white light emitting device includes a second phosphor and a violet semiconductor light emitting element that emits ultraviolet light or violet light as the semiconductor light emitting element, The second phosphor may be excited by the ultraviolet light or the violet light from the violet semiconductor light emitting element to emit the first blue light and the second blue light, thereby forming a white light emitting device.

[0010] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0011] At this time, the white light emitting device includes a second phosphor and a first blue semiconductor light emitting element that emits the first blue light as the semiconductor light emitting element, The second phosphor may be excited by the first blue light from the first blue semiconductor light emitting element to emit the second blue light, thereby forming a white light emitting device.

[0012] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0013] At this time, the white light emitting device includes a second phosphor, and as the semiconductor light emitting elements, a violet semiconductor light emitting element that emits the ultraviolet light or violet light, and a second blue semiconductor light emitting element that emits a second blue light, The second phosphor may be excited by the ultraviolet light or violet light from the violet semiconductor light emitting element to emit the first blue light, forming a white light emitting device.

[0014] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0015] In this case, the white light emitting device can be a white light emitting device that includes, as the semiconductor light emitting elements, a first blue semiconductor light emitting element that emits the first blue light and a second blue semiconductor light emitting element that emits the second blue light.

[0016] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0017] In this case, the white light emitting device may have a color temperature of 2700K to 12000K.

[0018] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0019] In this case, the white light emitting device may be one in which at least one of the half width of the first peak and the half width of the second peak is 50 nm or less.

[0020] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0021] In this case, the second phosphor may be a quantum dot phosphor, forming a white light emitting device.

[0022] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0023] In this case, the second phosphor is (Ba, Sr) 3 MgSi 2 O 8 : It is possible to provide a white light emitting device using a Eu-based phosphor.

[0024] This results in a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0025] In this case, the white light emitting device may be one in which the first phosphor contains an SAE phosphor, a LuAG phosphor or a YAG phosphor, and a CASN phosphor or a SCASN phosphor.

[0026] This results in a white light emitting device with higher luminous flux and higher color rendering.

[0027] In this case, the white light emitting device may include a layer containing the second phosphor between the semiconductor light emitting element and the layer containing the first phosphor.

[0028] This results in a white light emitting device with higher color rendering properties. Effect of the Invention

[0029] As described above, according to the white light emitting device of the present invention, it is possible to easily provide a white light emitting device with high luminous flux and high color rendering. [Brief description of the drawings]

[0030] [Figure 1] 1 is a diagram illustrating light emission in a white light emitting device according to the present invention. [Diagram 2] 1 is a diagram showing an example of the configuration of a white light emitting device according to a first modified example. [Diagram 3] 13 is a diagram illustrating light emission in a white light emitting device according to a first modified example. [Figure 4] 13 is a diagram showing a configuration example of a white light emitting device according to a second modified example. [Diagram 5] 13 is a diagram illustrating light emission in a white light emitting device according to a second modified example. [Figure 6] 13 is a diagram showing an example of the configuration of a white light emitting device according to a third modified example. [Figure 7] 13 is a diagram illustrating light emission in a white light emitting device according to a third modified example. [Figure 8] 13 is a diagram showing a configuration example of a white light emitting device according to a fourth modified example. [Figure 9] 13 is a diagram illustrating light emission in a white light emitting device according to a fourth modified example. [Figure 10] The results of Experimental Example 1, which investigated the relationship between the value of formula (4) and R9 and R12, are shown below. [Figure 11] The results of Experimental Example 2, which investigated the relationship between the value of formula (4) and R9 and R12, are shown below. [Figure 12] The results of Experimental Example 3, which investigated the relationship between the value of formula (4) and R9 and R12, are shown below. [Figure 13] The results of Experimental Example 4, which investigated the relationship between the value of formula (4) and R9 and R12, are shown below. [Figure 14] 1 is a diagram for explaining the relationship between emission peaks. [Figure 15] 1 is a diagram showing an example of an emission spectrum of a white light-emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As described above, there has been a demand for a white light emitting device that has high luminous flux and easily achieves high color rendering.

[0032] As a result of intensive research into the above-mentioned problems, the inventors have discovered a white light-emitting device comprising at least a semiconductor light-emitting element and a first phosphor, wherein the first phosphor is excited by at least one of a first blue light having a first peak at a peak wavelength P1 and a second blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum to emit visible light, and the white light-emitting device emits white light by the first blue light, the second blue light, and the visible light, The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensity at the first peak is Ip1, the emission intensity at the second peak is Ip2, and the emission intensity at a valley between the first peak and the second peak is Iv, 0.5≦(Ip1 / Ip2)≦2 (3) 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ··· (4) Fulfilling The inventors have found that a white light-emitting device having a high luminous flux and high color rendering can be easily provided by using a white light-emitting device that satisfies an average color rendering index Ra and a specific color rendering index Ri of 90 or more, and have completed the present invention.

[0033] The present invention will be described in detail below, but the present invention is not limited thereto. The following description will be given with reference to the drawings.

[0034] In this specification, regarding the relationship between emission color and wavelength, ultraviolet light or violet light refers to light having an emission peak at 320 to 430 nm, and blue light refers to light having an emission peak at 430 to 480 nm.

[0035] [White light emitting device] The white light emitting device according to the present invention is a white light emitting device including at least a semiconductor light emitting element and a first phosphor. A model of light emission in the white light emitting device according to the present invention is shown in FIG. 1. As shown in FIG. 1, the first phosphor is excited by at least one of a first blue light having a first peak at a peak wavelength P1 and a second blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum, and emits visible light. The white light emitting device according to the present invention emits white light by the first blue light, the second blue light, and the visible light.

[0036] 14 is a diagram for explaining the relationship of the emission peaks. The relationship between the purple light (ultraviolet light), the first blue light SS, the second blue light LL, and the visible light (green, red) is shown in FIG.

[0037] In the white light emitting device according to the present invention, the peak wavelength P1 and the peak wavelength P2 are: 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Meet the following.

[0038] As shown in an example of the spectrum waveform of a white light-emitting device in Fig. 15, a valley exists between a first peak of a peak wavelength P1 originating from the first blue light and a second peak of a peak wavelength P2 originating from the second blue light. As shown in Fig. 15, when the emission intensity at the first peak is Ip1, the emission intensity at the second peak is Ip2, and the emission intensity at the valley between the first peak and the second peak is Iv, the white light-emitting device according to the present invention has the following characteristics: 0.5≦(Ip1 / Ip2)≦2 (3) 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ··· (4) It satisfies the following.

[0039] In such a white light emitting device, the peak wavelengths and emission intensities of the first blue light SS having a first peak and the second blue light LL having a second peak, and the emission intensities of the valleys between the first peak of the first blue light SS and the second peak of the second blue light LL are specified to satisfy formulas (1) to (4), so that it is possible to more easily provide a white light emitting device with high luminous flux and high color rendering that satisfies an average color rendering index Ra and a special color rendering index Ri (i=1 to 15) of 90 or more over the entire range. More preferably, it is possible to easily provide a white light emitting device that outputs output light with a high color rendering index, such as a color rendering index Ri (i=1 to 15) of 90 or more over the entire range and an average color rendering index Ra of 95 or more.

[0040] (First phosphor) The first phosphor is excited by at least one of the first blue light SS and the second blue light LL to emit visible light, and is not particularly limited as long as it emits white light by the first blue light, the second blue light, and the visible light from the first phosphor. The first phosphor may be either an inorganic phosphor or an organic phosphor. For example, a combination of a green phosphor or a yellow phosphor with a red phosphor may be used. The visible light may be, for example, green light and red light as shown in FIG. 15, and in such a case, the first phosphor may include a green phosphor and a red phosphor. Specifically, the first phosphor may be a phosphor that is a combination of one or more aluminate phosphors such as SAE and LuAG·YAG, and nitride phosphors such as CASN·SCASN. In particular, the first phosphor may include an SAE phosphor, a LuAG phosphor or a YAG phosphor, and a CASN phosphor or a SCASN phosphor. By using such phosphors, a white light emitting device with higher luminous flux and higher color rendering can be obtained.

[0041] (1st and 2nd blue lights) The first blue light is blue light having a first peak at a peak wavelength P1 in the wavelength range of 430 to 480 nm of the emission spectrum, and the second blue light is blue light having a second peak at a peak wavelength P2 in the wavelength range of 430 to 480 nm of the emission spectrum. The light emission source and the like are not particularly limited as long as the blue light satisfies the above formulas (1) to (4). At least one of the first blue light and the second blue light may be visible light generated by exciting a phosphor (second phosphor) with light from a semiconductor light-emitting element, or may be blue light emitted by a blue semiconductor light-emitting element. Specific embodiments of these will be described in Modifications 1 to 4.

[0042] Here, at least one of the half width at half maximum (FWMH) of the first peak at peak wavelength P1 and the half width at half maximum (FWMH) of the second peak at peak wavelength P2 is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. If the half width of the first and / or second peak is 50 nm or less, a sufficient valley is formed between the first peak and the second peak, resulting in a white light-emitting device with higher luminous flux and higher color rendering.

[0043] Modified examples of the white light emitting device according to the present invention will be described below, but some aspects that have already been described may be omitted.

[0044] [First Modification] FIG. 2 shows a configuration example of a white light emitting device 100 according to a first modification of the present invention. FIG. 3 shows a model of light emission in the white light emitting device 100. As shown in FIG. 2, the white light emitting device 100 according to the first modification of the present invention may include a purple semiconductor light emitting element (ultraviolet LED or purple LED) 13 that emits ultraviolet light or purple light as a semiconductor light emitting element, and a second phosphor 1 that is excited by receiving the ultraviolet light or purple light and emits the first blue light SS and the second blue light LL, taking into consideration the light emission efficiency and mass productivity of the chip. In other words, both the first peak and the second peak correspond to the case where they are derived from the emission of the second phosphor 1 that is excited by the ultraviolet light or purple light emitted from the purple semiconductor light emitting element 13. More specifically, as shown in FIGS. 2 and 3, the second phosphor 1 includes a first blue phosphor 23 that is excited by the ultraviolet light or purple light from the purple semiconductor light emitting element 13 and emits the first blue light SS, and a second blue phosphor 24 that emits the second blue light LL. Then, white light is emitted by the first blue light SS, the second blue light LL, and visible light from the first phosphor 2 excited by these lights.

[0045] The first phosphor 2 that emits light when excited by a first blue light SS having a first peak due to a first blue phosphor 23 and a second blue light LL having a second peak due to a second blue phosphor 24 can be provided, and includes a green phosphor 21 and a red phosphor 22.

[0046] The second phosphor 1 is not particularly limited as long as it emits light having a peak wavelength greater than the peak wavelength of the light emitted from the semiconductor light emitting element. Examples of the second phosphor include quantum dot (QD) phosphors and (Ba, Sr) 3 MgSi 2 O 8 It is preferable to use a phosphor of the Ba, Sr system. A quantum dot phosphor is a material whose emission characteristics such as the emission peak wavelength can be easily controlled by adjusting the particle size (particle size), and it has a high luminous flux and is easier to achieve high color rendering. 3 MgSi 2 O 8 The peak wavelength of the Eu-based blue phosphor can be shifted to the longer wavelength side by replacing at least a part of Ba with Sr. By using these phosphors, it is easy to adjust the phosphor that emits blue light that satisfies the above formulas (1) to (4), and it becomes easier to obtain a phosphor with high luminous flux and high color rendering. The same applies to the other modified examples of the second phosphor 1 described later.

[0047] It is also preferable to provide a layer 4 containing the second phosphor 1 between the semiconductor light emitting element and the layer containing the first phosphor 2. This results in a white light emitting device with higher color rendering properties.

[0048] The phosphor and the semiconductor light emitting element may be dispersed in a phosphor layer 20 made of resin, glass, or the like, which also functions as a sealant, and housed in a package 30. In addition to the resin, for example, a filler 3 or an additive for enhancing the dispersibility of the phosphor may be appropriately added to the phosphor layer 20. The package 30 and the substrate 40 may be integrally molded. This is the same in other modified examples described later.

[0049] In such a white light emitting device 100, the first blue light SS having a first peak and the second blue light LL having a second peak are emitted from the second phosphor 1, so that it is possible to more easily provide a white light emitting device with high luminous flux and high color rendering. Furthermore, since only one semiconductor light emitting element (LED) is used, it is less expensive and has a cost advantage. Furthermore, when two blue semiconductor light emitting elements (blue LEDs) are used in series, a power supply voltage for driving two blue semiconductor light emitting elements (blue LEDs) is required, but when a white light emitting device such as that shown in FIG. 2 is used, only a power supply voltage for driving one semiconductor light emitting element is required. Furthermore, depending on the light emitting characteristics (peak wavelength) of the blue semiconductor light emitting element (blue LED), it may be difficult to obtain it stably, but the white light emitting device 100 shown in FIG. 1 can avoid such a problem.

[0050] Thus, the white light emitting device 100 according to this modification has a high luminous flux, and allows for greater freedom in designing a white light emitting device with high color rendering, making it possible to provide it more stably. In addition, since only one semiconductor light emitting device is used, the white light emitting device 100 can be manufactured at a lower cost.

[0051] [Second modified example] FIG. 4 shows a configuration example of a white light emitting device 200 according to a second modification of the present invention. FIG. 5 shows a model of light emission in the white light emitting device 200. As shown in FIGS. 4 and 5, the white light emitting device 200 according to the second modification of the present invention includes a first blue semiconductor light emitting element 11 (first blue LED) that emits a first blue light SS as a semiconductor light emitting element, and a second blue phosphor 24 that is a second phosphor that is excited by the first blue light SS from the first blue semiconductor light emitting element 11 and emits a second blue light LL. In other words, the second blue light LL corresponds to a case where the second phosphor is excited by the light emitted from the first blue semiconductor light emitting element 11 (first blue LED) to emit light. Then, white light is emitted by the first blue light SS, the second blue light LL, and the visible light from the first phosphor 2 excited by them.

[0052] The blue light having the first peak at peak wavelength P1 and the second peak at peak wavelength P2 refers to the entire "light" that combines the "light emitted from the semiconductor light-emitting element" and the "light emitted from the phosphor" in the wavelength range of 430 to 480 nm of the emission spectrum, and does not necessarily mean the blue light of each of the "light emitted from the semiconductor light-emitting element" and the "light emitted from the phosphor."

[0053] The first phosphor 2 (e.g., green phosphor 21, red phosphor 22) emits light when excited by the first blue light SS from the first blue semiconductor light emitting element (first blue LED) 11 or the second blue light LL from the second phosphor 1, as in the white light emitting device 100 of FIG. 2. This modification also makes it possible to easily provide a white light emitting device with high luminous flux and high color rendering. In addition, since only one blue semiconductor light emitting element (blue LED) is used as the semiconductor light emitting element, the design has a higher degree of freedom than in the past. Furthermore, it is cost-effective as in the case of the white light emitting device 100 of FIG. 2. In addition, there is no need to connect multiple blue semiconductor light emitting elements (blue LEDs) in series to equalize the current flowing through the multiple blue semiconductor light emitting elements (blue LEDs), and only the power supply voltage for driving one semiconductor light emitting element is required.

[0054] [Third modified example] FIG. 6 shows a configuration example of a white light emitting device 300 according to a third modification of the present invention. FIG. 7 shows a model of light emission in the white light emitting device 300. As shown in FIGS. 6 and 7, the white light emitting device 300 according to the third modification of the present invention uses two semiconductor light emitting elements, a purple semiconductor light emitting element 13 (ultraviolet LED or purple LED) that emits ultraviolet light or purple light, and a second blue semiconductor light emitting element 12 (second blue LED) that emits second blue light LL, as the semiconductor light emitting element, and may also include a second blue phosphor 23 as a second phosphor that is excited by the ultraviolet light or purple light from the purple semiconductor light emitting element 13 and emits the first blue light SS. In other words, this corresponds to the case where the first peak is derived from light excited by the second phosphor 1 by the light emitted from the purple semiconductor light emitting element 13 (ultraviolet LED or purple LED). Then, white light is emitted by the first blue light SS, the second blue light LL, and the visible light from the first phosphor 2 excited by these. Such a white light emitting device can easily provide a white light emitting device with high luminous flux and high color rendering. In the case of this modification, too, a white light emitting device with high luminous flux and high color rendering can easily be provided.

[0055] [Fourth Variation] FIG. 8 shows a configuration example of a white light emitting device 400 according to a fourth modification of the present invention. FIG. 9 shows a model of light emission in the white light emitting device 400. As shown in FIGS. 8 and 9, the white light emitting device 400 according to the fourth modification of the present invention uses a plurality of blue semiconductor light emitting elements (blue LEDs) as semiconductor light emitting elements, including a first blue semiconductor light emitting element 11 (first blue LED) that emits a first blue light SS having a first peak and a second blue semiconductor light emitting element 12 (second blue LED) that emits a second blue light LL having a second peak, and does not use a second phosphor. Then, white light is emitted by the first blue light SS, the second blue light LL, and visible light from the first phosphor 2 excited by these lights. In the case of this modification, it is also possible to easily provide a white light emitting device with high luminous flux and high color rendering.

[0056] As in the first to third modified examples described above, at least one of the first blue light SS having a first peak at a peak wavelength P1 and the second blue light LL having a second peak at a peak wavelength P2 is preferably derived from light excited by the second phosphor with light emitted from the semiconductor light emitting element. The emission from the phosphor has smaller variations in emission characteristics such as the wavelength of the emission peak and the half width compared to the emission from an LED. Therefore, with such a white light emitting device, the selection and setting of the semiconductor light emitting element is easier than in the fourth modified example using two semiconductor light emitting elements, the first blue semiconductor light emitting element (blue LED) emitting the first blue light SS having a first peak and the second blue semiconductor light emitting element (blue LED) emitting the second blue light LL having a second peak, and the degree of freedom in design is increased, and a white light emitting device with high luminous flux and high color rendering can be provided. Moreover, the decrease in the utilization efficiency of the semiconductor light emitting element can be suppressed.

[0057] [Experimental Example] The following describes the results of evaluation of the light emitting characteristics of white light emitting device 400 of the fourth modified example described above, but the present invention is not limited thereto.

[0058] (Experimental Example 1) As the first blue semiconductor light-emitting element 11 (first blue LED) and the second blue semiconductor light-emitting element 12 (second blue LED), multiple blue LEDs with different emission wavelengths and half-widths that satisfy the above formulas (1) to (3) and further have different values ​​for formula (4) were combined to evaluate the relationship between the high color rendering properties of the white light-emitting device and the emission intensity Iv of the valley between the first peak and the second peak.

[0059] In the experimental examples 1 to 4, the first blue semiconductor light emitting element 11 (first blue LED) and the second blue semiconductor light emitting element 12 (second blue LED) were semiconductor light emitting elements with InGaN active layers, and the first phosphor 2 was an SAE phosphor with a peak emission wavelength of 496 nm, an LuAG phosphor with a peak emission wavelength of 542 nm, and a CASN phosphor with a peak emission wavelength of 652 nm.

[0060] Table 1 shows the conditions and results when the color temperature of the white light emitting device was 5000K.

[0061] [Table 1]

[0062] In Table 1, Ri values ​​for which Ri<90 are R9, R10, and R12, are shown. Focusing on R9 and R12, which are the most stringent criteria for Ri≧90 when outputting white light from a combination of a light-emitting element and a phosphor, Fig. 10 shows a plot of the value of formula (4) on the horizontal axis and R9 and R12 on the vertical axis. It can be seen that Ri≧90 is achieved in the range of 0.25≦Iv / {(Ip1+Ip2) / 2}≦0.55, and that when Iv / {(Ip1+Ip2) / 2} peaks at 0.30 (30%) to 0.40 (40%), R12 falls short of the criteria for Ri≧90 when it is lower than 0.25, and R9 and R12 fall short of the criteria for Ri≧90 when it is greater than 0.55.

[0063] (Experimental Example 2) Next, in Experimental Example 2, P1 and P2 were fixed, and the chromaticity (x, y) was changed within a range of three MacAdam steps to evaluate the optical characteristics of white light. The conditions and results are shown in Table 2.

[0064] [Table 2]

[0065] In addition, in Table 2, focusing on R9 and R12, which are the most stringent criteria for Ri≧90 when outputting white light from a combination of a light-emitting element and a phosphor, Fig. 11 shows a plot of the value of formula (4) on the horizontal axis and R9 and R12 on the vertical axis. It can be seen that Ri≧90 is achieved when Iv / {(Ip1+Ip2) / 2} is in the range of 0.25≦Iv / {(Ip1+Ip2) / 2}≦0.55, and when Iv / {(Ip1+Ip2) / 2} is lower than 0.25, it falls short of the criterion for Ri≧90, and when it is greater than 0.55, it falls short of the criterion for Ri≧90 for both R9 and R12.

[0066] (Experimental Example 3) Next, as Experimental Example 3, an evaluation was performed on a white light emitting device with a color temperature of 2700 K. Table 3 shows the conditions and results.

[0067] [Table 3]

[0068] In addition, in Table 3, focusing on R9 and R12, which are the strictest criteria for Ri≧90 when outputting white light from a combination of a light-emitting element and a phosphor, Fig. 12 shows a plot of the value of formula (4) on the horizontal axis and R9 and R12 on the vertical axis. It can be seen that Ri≧90 is achieved when Iv / {(Ip1+Ip2) / 2} is in the range of 0.25≦Iv / {(Ip1+Ip2) / 2}≦0.55, and when Iv / {(Ip1+Ip2) / 2} is lower than 0.15, with a peak at around 0.30 (30%), the criterion for Ri≧90 is not met for R12, and when it is greater than 0.55, the criterion for Ri≧90 is not met for R9.

[0069] (Experimental Example 4) Next, as Experimental Example 4, an evaluation was performed on a white light emitting device with a color temperature of 12000 K. Table 4 shows the conditions and results.

[0070] [Table 4]

[0071] In addition, in Table 4, focusing on R9 and R12, which are the strictest criteria for Ri≧90 when outputting white light from a combination of a light-emitting element and a phosphor, Fig. 13 shows a plot of the value of formula (4) on the horizontal axis and R9 and R12 on the vertical axis. It can be seen that Ri≧90 is achieved when Iv / {(Ip1+Ip2) / 2} is in the range of 0.25≦Iv / {(Ip1+Ip2) / 2}≦0.55, and when Iv / {(Ip1+Ip2) / 2} peaks at 0.30 (30%) to 0.40 (40%), R12 falls short of the criterion for Ri≧90 when it is lower than 0.25, and when it is greater than 0.55, R9 and R12 fall short of the criterion for Ri≧90.

[0072] As shown in Experimental Examples 1 to 4, it was found that if the white light emitting device of the present invention satisfies the formula (4) of 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5, the standard of Ri≧90 is met regardless of the color temperature. In particular, it was found that the white light emitting device of the present invention that satisfies the formula (4) outputs a white light emitting device that outputs a high color rendering index, such as a color rendering index Ri (i=1 to 15) of 90 or more over the entire range and an average color rendering index Ra of 95 or more. Thus, according to the white light emitting device of the present invention, it is easy to obtain a white light emitting device with high luminous flux and high color rendering.

[0073] The present specification includes the following aspects. [1]: A white light emitting device comprising at least a semiconductor light emitting element and a first phosphor, the first phosphor is excited by at least one of a first blue light having a first peak at a peak wavelength P1 and a second blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum to emit visible light; the white light emitting device emits white light by the first blue light, the second blue light, and the visible light; The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensity at the first peak is Ip1, the emission intensity at the second peak is Ip2, and the emission intensity at a valley between the first peak and the second peak is Iv, 0.5≦(Ip1 / Ip2)≦2 (3) 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ··· (4) Fulfilling A white light emitting device characterized in that it has an average color rendering index Ra and a specific color rendering index Ri of 90 or more. [2]: the white light emitting device includes a second phosphor and a violet semiconductor light emitting element that emits ultraviolet light or violet light as the semiconductor light emitting element; The white light-emitting device of [1] above, wherein the second phosphor is excited by the ultraviolet light or purple light from the purple semiconductor light-emitting element to emit the first blue light and the second blue light. [3]: the white light emitting device includes a second phosphor and a first blue semiconductor light emitting element that emits the first blue light as the semiconductor light emitting element; The white light emitting device according to [1] above, wherein the second phosphor is excited by the first blue light from the first blue semiconductor light emitting element to emit the second blue light. [4]: the white light emitting device includes a second phosphor, and as the semiconductor light emitting elements, a violet semiconductor light emitting element that emits the ultraviolet light or violet light, and a second blue semiconductor light emitting element that emits a second blue light; The white light emitting device according to [1] above, wherein the second phosphor is excited by the ultraviolet light or purple light from the purple semiconductor light emitting element to emit the first blue light. [5]: The white light-emitting device according to [1] above, comprising, as the semiconductor light-emitting elements, a first blue semiconductor light-emitting element that emits the first blue light and a second blue semiconductor light-emitting element that emits the second blue light. [6]: The white light emitting device according to [1], [2], [3], [4] or [5], wherein the white light has a color temperature of 2700K to 12000K. [7]: The white light-emitting device according to [1], [2], [3], [4], [5] or [6], wherein at least one of a half width of the first peak and a half width of the second peak is 50 nm or less. [8]: The white light emitting device according to the above [2], [3] or [4], wherein the second phosphor is a quantum dot phosphor. [9]: The second phosphor is (Ba, Sr) 3 MgSi 2 O 8 The white light emitting device according to the above [2], [3], [4] or [8], wherein the phosphor is a Eu-based phosphor.

[10] : The white light-emitting device according to [1], [2], [3], [4], [5], [6], [7], [8] or [9], wherein the first phosphor comprises an SAE phosphor, a LuAG-based phosphor or a YAG-based phosphor, and a CASN-based phosphor or a SCASN-based phosphor.

[11] : The white light-emitting device according to [2], [3], [4], [8] or [9], further comprising a layer containing the second phosphor between the semiconductor light-emitting element and the layer containing the first phosphor.

[0074] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0075] 1... second phosphor, 2... first phosphor, 3... filler, 4...Layer containing a second phosphor; 11...first blue semiconductor light emitting element (blue LED), 12...Second blue semiconductor light emitting element (blue LED), 13... Purple semiconductor light emitting element (ultraviolet LED or purple LED), 20... phosphor layer, 21... green phosphor (first phosphor), 22... red phosphor (first phosphor), 23...first blue phosphor (second phosphor), 24...second blue phosphor (second phosphor), 30...package, 40...substrate, 100, 200, 300, 400...White light-emitting device. SS...first blue light, LL...second blue light, L...white light.

Claims

1. A white light emitting device comprising at least a semiconductor light emitting element and a first phosphor, the first phosphor is excited by at least one of a first blue light having a first peak at a peak wavelength P1 and a second blue light having a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum to emit visible light; the white light emitting device emits white light by the first blue light, the second blue light, and the visible light; The peak wavelength P1 and the peak wavelength P2 are 430 nm≦P1<P2≦480 nm (1) P2-P1≧16nm... (2) Fulfilling When the emission intensity at the first peak is Ip1, the emission intensity at the second peak is Ip2, and the emission intensity at a valley between the first peak and the second peak is Iv, 0.5≦(Ip1 / Ip2)≦2... (3) 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5... (4) Fulfilling A white light emitting device having an average color rendering index Ra and a specific color rendering index Ri of 90 or more.

2. the white light emitting device includes a second phosphor and a violet semiconductor light emitting element that emits ultraviolet light or violet light as the semiconductor light emitting element, 2. The white light-emitting device according to claim 1, wherein the second phosphor is excited by the ultraviolet light or purple light from the purple semiconductor light-emitting element to emit the first blue light and the second blue light.

3. the white light emitting device includes a second phosphor and a first blue semiconductor light emitting element that emits the first blue light as the semiconductor light emitting element, 2. The white light emitting device according to claim 1, wherein the second phosphor is excited by the first blue light from the first blue semiconductor light emitting element to emit the second blue light.

4. the white light emitting device includes a second phosphor, and a violet semiconductor light emitting element that emits the ultraviolet light or violet light and a second blue semiconductor light emitting element that emits a second blue light as the semiconductor light emitting elements; 2. The white light emitting device according to claim 1, wherein the second phosphor is excited by the ultraviolet light or the violet light from the violet semiconductor light emitting element to emit the first blue light.

5. The white light emitting device according to claim 1, characterized in that the white light emitting device comprises, as the semiconductor light emitting elements, a first blue semiconductor light emitting element that emits the first blue light and a second blue semiconductor light emitting element that emits the second blue light.

6. 2. The white light emitting device according to claim 1, wherein the white light has a color temperature of 2700K to 12000K.

7. 7. The white light emitting device according to claim 1, wherein at least one of a half width of the first peak and a half width of the second peak is 50 nm or less.

8. 5. The white light emitting device according to claim 2, wherein the second phosphor is a quantum dot phosphor.

9. The second phosphor is (Ba, Sr) ３ MgSi ２ O ８ 9. The white light emitting device according to claim 8, wherein the phosphor is a Eu-based phosphor.

10. 8. The white light emitting device according to claim 7, wherein the first phosphor includes an SAE phosphor, a LuAG-based phosphor or a YAG-based phosphor, and a CASN-based phosphor or a SCASN-based phosphor.

11. 5. The white light emitting device according to claim 2, further comprising a layer containing the second phosphor between the semiconductor light emitting element and the layer containing the first phosphor.

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