White light emitting device

Abstract

To provide a white light emitting device which has high brightness and facilitates high color rendering.SOLUTION: A white light emitting device includes: a semiconductor light-emitting element 13; a first phosphor 1 that is excited by the light from the semiconductor light-emitting element and emits light with a peak wavelength greater than a peak wavelength of the light; and a second phosphor 2 that is excited by at least one of the light emitted from the semiconductor light-emitting element and the light emitted from the first phosphor and emits light. The light emitted from the semiconductor light-emitting element and the first phosphor includes blue light having a first peak with a peak wavelength P1 and a second peak with a peak wavelength P2 in the wavelength range of 430 to 480 nm. At least one of the first peak and the second peak originates from the light emission that has excited the first phosphor. The peak wavelength P1, peak wavelength P2, light emission intensity Ip1 at the first peak and light emission intensity Ip2 at the second peak satisfy (1) 430 nm≤P1<P2≤480 nm, (2) P2-P1≥16 nm, (3) 0.5≤(Ip1 / Ip2)≤2.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 light emitted by the LED and phosphors.

[0003] Conventionally, a method has been proposed in which green, yellow, 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). Also proposed is a method in which yellow and red phosphors are excited by two blue LEDs with different wavelengths and a green LED is further added, and a method in which two blue LEDs, a green LED, and a red LED are used (see, for example, Patent Document 2). Still further, a method has been proposed in which green, red, and other phosphors are excited by two blue LEDs with different wavelengths to obtain white light with high color rendering (see, for example, Patent Document 3).

[0004] FIG. 7 shows an example of a conventional white light emitting device (for example, Patent Document 3). FIG. 8 is a diagram for explaining the relationship of emission peaks. A conventional white light emitting device 400 includes a blue semiconductor light emitting element (blue LED) 11 that emits blue light having a first peak at a peak wavelength P1 and a blue semiconductor light emitting element (blue LED) 12 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, and a second phosphor 2 such as a green phosphor 21 and a red phosphor 22 is dispersed together with a filler 3 in a phosphor layer 20 that also functions as a sealant made of a resin or glass that covers the blue semiconductor light emitting elements (blue LEDs) 11 and 12. In such a white light emitting device, the second phosphor 2 is excited by the two blue LEDs 11 and 12 that have different wavelengths to obtain white light L with high color rendering. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-034188 A [Patent Document 2] JP 2011-192738 A [Patent Document 3] JP 2016-219519 A Summary of the Invention [Problem to be solved by the invention]

[0006] Blue semiconductor light-emitting elements (sometimes called blue LEDs) usually have variations in light-emitting characteristics (e.g., emission peak wavelength and half-width of peak) due to deviations in the composition ratio and crystallinity of the epitaxial layer including the light-emitting layer formed on the wafer. As a result, as in the above-mentioned conventional technology, when multiple blue LEDs are used as a light source of blue light for exciting phosphors such as green, yellow, and red, it was necessary to appropriately change the combination taking into account the variations in the light-emitting characteristics of each blue LED, since the light-emitting characteristics at the light-emitting peak derived from each blue LED are different. Specifically, when multiple blue LEDs are used, the difference P2-P1 between the peak wavelength P1 of the light-emitting peak on the short wavelength side and the peak wavelength P2 of the light-emitting peak on the long wavelength side is an important factor for achieving high color rendering, and it was necessary to select an appropriate one from among blue LEDs having an emission peak on the short wavelength side with a certain variation and blue LEDs having an emission peak on the long wavelength side with a certain variation, taking into account the characteristics when combined. This resulted in restrictions on the degree of freedom in designing the light-emitting device, and required a great deal of effort to achieve an appropriate combination. In addition, there was a problem that blue LEDs that could not be combined were wasted.

[0007] 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 luminance and easily achieves high color rendering. [Means for solving the problem]

[0008] The present invention has been made in order to achieve the above object, and provides a white light emitting device including a semiconductor light emitting element, a first phosphor that is excited by light emitted from the semiconductor light emitting element and emits light having a peak wavelength larger than the peak wavelength of the light emitted from the semiconductor light emitting element, and a second phosphor that is excited by at least one of the light emitted from the semiconductor light emitting element and the light emitted from the first phosphor and emits light, the light emitted from the semiconductor light-emitting element and the first phosphor includes blue light having a first peak at a peak wavelength P1 and a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum; At least one of the first peak and the second peak is derived from light emission produced when the first phosphor is excited by light emitted from the semiconductor light emitting element, The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensities at the first peak and the second peak are Ip1 and Ip2, respectively, 0.5≦(Ip1 / Ip2)≦2 (3) The present invention provides a white light emitting device that satisfies the above requirements.

[0009] Such a white light emitting device can easily achieve high luminance and high color rendering.

[0010] In this case, the semiconductor light emitting element emits ultraviolet light or violet light, The first phosphor can be a white light-emitting device that is excited by the ultraviolet light or violet light emitted from the semiconductor light-emitting element to emit blue light having the first peak and the second peak.

[0011] This makes it easier to produce a white light emitting device with high luminance and high color rendering.

[0012] At this time, the semiconductor light emitting element emits a first blue light having the first peak, The first phosphor may be a white light emitting device that is excited by the first blue light emitted from the semiconductor light emitting element to emit second blue light having the second peak.

[0013] This makes it easier to produce a white light emitting device with high luminance and high color rendering.

[0014] At this time, the semiconductor light emitting element includes a first semiconductor light emitting element and a second semiconductor light emitting element, the first semiconductor light emitting element emits ultraviolet light or violet light, the first phosphor is excited by the ultraviolet light or violet light emitted from the first semiconductor light emitting element to emit a first blue light having the first peak; The second semiconductor light emitting element may be a white light emitting device that emits second blue light having the second peak.

[0015] This makes it easier to produce a white light emitting device with high luminance and high color rendering.

[0016] 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.

[0017] This results in a white light emitting device with higher luminance and better color rendering.

[0018] In this case, if the emission spectrum has a valley between the first peak and the second peak, the emission intensity of the first peak is Ip1, the emission intensity of the second peak is Ip2, and the emission intensity of the valley between the first peak and the second peak is Iv, then: 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ···(4) The above conditions may be satisfied.

[0019] This results in a white light emitting device capable of outputting white light with even higher color rendering.

[0020] In this case, the first phosphor may be a quantum dot phosphor, forming a white light emitting device.

[0021] This results in a white light emitting device whose color rendering properties can be more easily adjusted.

[0022] In this case, the first phosphor may be a (Ba, Sr)3MgSi2O8:Eu-based phosphor, forming a white light emitting device.

[0023] This results in a white light emitting device whose color rendering properties can be more easily adjusted.

[0024] In this case, the white light emitting device may be one in which the second phosphor contains an SAE phosphor, a LuAG phosphor or a YAG phosphor, and a CASN phosphor or a SCASN phosphor.

[0025] This results in a white light emitting device with higher luminance and better color rendering.

[0026] In this case, the white light emitting device may include a layer containing the first phosphor between the semiconductor light emitting element and the layer containing the second phosphor.

[0027] This results in a white light emitting device with higher color rendering properties. Effect of the Invention

[0028] As described above, the white light emitting device of the present invention provides a white light emitting device that has high luminance and easily achieves high color rendering. [Brief description of the drawings]

[0029] [Figure 1] 1 is a diagram showing a first embodiment of a white light emitting device according to the present invention. [Diagram 2] 1 is a diagram illustrating light emission in the white light emitting device of the first embodiment. [Diagram 3] 4 is a diagram showing a second embodiment of a white light emitting device according to the present invention. [Figure 4] 11 is a diagram illustrating light emission in a white light emitting device according to a second embodiment. [Diagram 5] 4 is a diagram showing a third embodiment of a white light emitting device according to the present invention. [Figure 6] 13 is a diagram illustrating light emission in a white light emitting device according to a third embodiment. [Figure 7] 1 is a diagram showing a conventional white light emitting device equipped with two blue LEDs. [Figure 8]1 is a diagram for explaining the relationship between emission peaks. [Figure 9] 1 is a diagram showing an example of the emission spectrum of the white light emitting devices according to the first to third embodiments of the present invention. [Figure 10] 1 shows an example of the distribution of dominant wavelengths generated in one lot of blue semiconductor light-emitting elements. [Figure 11] An example of the distribution of dominant wavelengths in 17 lots of blue phosphors is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention will be described in detail below, but the present invention is not limited thereto.

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

[0032] As a result of intensive research into the above-mentioned problems, the inventors have discovered a white light-emitting device including a semiconductor light-emitting element, a first phosphor that is excited by light emitted from the semiconductor light-emitting element and emits light having a peak wavelength larger than the peak wavelength of the light emitted from the semiconductor light-emitting element, and a second phosphor that is excited by at least one of the light emitted from the semiconductor light-emitting element and the light emitted from the first phosphor and emits light, the light emitted from the semiconductor light-emitting element and the first phosphor includes blue light having a first peak at a peak wavelength P1 and a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum; At least one of the first peak and the second peak is derived from light emission produced when the first phosphor is excited by light emitted from the semiconductor light emitting element, The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensities at the first peak and the second peak are Ip1 and Ip2, respectively, 0.5≦(Ip1 / Ip2)≦2 (3) The inventors have found that a white light emitting device that satisfies the above requirements can provide a white light emitting device that has high luminance and easily achieves high color rendering, and have completed the present invention.

[0033] The following description will be given with reference to the drawings. 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.

[0034] [White light emitting device]

[0035] A white light-emitting device according to an embodiment of the present invention includes a semiconductor light-emitting element, a first phosphor that is excited by light emitted from the semiconductor light-emitting element and emits light having a peak wavelength longer than the peak wavelength of the light emitted from the semiconductor light-emitting element, and a second phosphor that is excited by at least one of the light emitted from the semiconductor light-emitting element and the light emitted from the first phosphor and emits light.

[0036] The light emitted from the above-mentioned semiconductor light-emitting element and first phosphor contains blue light having a first peak at peak wavelength P1 and a second peak at peak wavelength P2 in the wavelength range of 430 to 480 nm of the emission spectrum. Here, "light emitted from the semiconductor light-emitting element and the first phosphor" means the entire "light" that is a combination of "light emitted from the semiconductor light-emitting element" and "light emitted from the first phosphor", and does not necessarily mean that each of "light emitted from the semiconductor light-emitting element" and "light emitted from the first phosphor" is blue light having a first peak and a second peak.

[0037] At least one of the first peak and the second peak is derived from the emission of light generated when the first phosphor is excited by the light emitted from the semiconductor light emitting element. The emission of light generated by phosphors has smaller variations in emission characteristics such as the wavelength and half width of the emission peak compared to the emission of light generated by LEDs. This is demonstrated by the distribution of dominant wavelengths generated for one lot of blue semiconductor light emitting elements shown in FIG. 10 and the distribution of dominant wavelengths generated for 17 lots of blue phosphors (BAM (BaMgAl 10 O 17 The following will be explained using a blue semiconductor light-emitting element (Eu) phosphor). The examples shown in Figs. 10 and 11 are for comparing and explaining the difference in the distribution (variation) of the dominant wavelengths of a semiconductor light-emitting element and a phosphor in the same wavelength range, and do not limit the materials used in the present invention. In Figs. 10 and 11, the vertical axis represents the occurrence distribution (frequency) and the horizontal axis is scaled to the same wavelength width, so that the variation of the dominant wavelengths in the same wavelength width can be compared from Figs. 10 and 11. As is clear from a comparison of Figs. 10 and 11, the variation of the dominant wavelengths of the phosphor is extremely small compared to the variation of the dominant wavelengths of the blue semiconductor light-emitting element.

[0038] Therefore, with such a white light emitting device, compared to a case where two semiconductor light emitting elements are used, a blue semiconductor light emitting element (blue LED) that emits blue light having a first peak and a blue semiconductor light emitting element (blue LED) that emits blue light having a second peak, the selection and setting of the semiconductor light emitting elements is easier, the degree of freedom in design is higher, and a white light emitting device that easily achieves high brightness and high color rendering can be provided. Moreover, a decrease in the utilization efficiency of the semiconductor light emitting elements can be suppressed.

[0039] The second phosphor is not particularly limited as long as it is excited by at least one of the light emitted from the semiconductor light emitting element and the light emitted from the first phosphor to emit light and form a white light emitting device. For example, a combination of a green phosphor or a yellow phosphor with a red phosphor can be used.

[0040] In the white light emitting device according to the present invention, at least one of the first peak of the first blue light SS and the second peak of the second blue light LL is derived from the emission of light generated by the first phosphor excited by the light emitted from the semiconductor light emitting element. The peak wavelength P1 of the first blue light SS and the peak wavelength P2 of the second blue light LL are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) and further, when the emission intensities at the first peak of the first blue light SS and the second peak of the second blue light LL are Ip1 and Ip2, respectively, 0.5≦(Ip1 / Ip2)≦2 (3) It satisfies the following.

[0041] If the second phosphor is excited using the first and second blue lights SS and LL that satisfy the above formulas (1) to (3), a white light emitting device can be obtained that easily outputs output light L with a high color rendering index, such as 90 or more over the entire range of color rendering index Ri (i=1 to 15). More preferably, a white light emitting device can be obtained that easily outputs output light with a high color rendering index, such as 90 or more over the entire range of color rendering index Ri (i=1 to 15) and an average color rendering index Ra of 95 or more.

[0042] Here, as the semiconductor light-emitting element, a semiconductor light-emitting element (ultraviolet LED or purple LED) that emits ultraviolet light or purple light is used in consideration of the light-emitting efficiency of the chip, and as a measure against problems such as a decrease in the degree of freedom in designing a light-emitting device due to variations in the emission wavelength of the semiconductor light-emitting element (ultraviolet LED or purple LED), it is preferable to use a first phosphor that is excited by the ultraviolet light or purple light emitted from the semiconductor light-emitting element to emit first and second blue lights SS and LL having a first peak and a second peak. In other words, both the blue light SS of the first peak and the blue light LL of the second peak correspond to the case where the first phosphor originates from the emission excited by the ultraviolet light or purple light emitted from the semiconductor light-emitting element (ultraviolet LED or purple LED). An example of such a white light-emitting device is shown in FIG. 1. Also, a model of the emission in the white light-emitting device of FIG. 1 is shown in FIG. 2.

[0043] The white light emitting device 100 according to the first embodiment of the present invention shown in Fig. 1 includes a semiconductor light emitting element (ultraviolet LED or purple LED) 13 that emits ultraviolet light or purple light as a semiconductor light emitting element on a substrate 40. The first phosphor 1 is excited by the light emitted from the semiconductor light emitting element (ultraviolet LED or purple LED) 13 to emit blue light having a first peak and a second peak, specifically, includes a blue phosphor 23 that is excited by ultraviolet light or purple light to emit blue light SS having a first peak, and a blue phosphor 24 that is excited by ultraviolet light or purple light to emit blue light LL having a second peak. This results in a white light emitting device that emits white light L with high color rendering.

[0044] Also, green phosphor 21 and red phosphor 22 are provided as second phosphor 2 that emits light when excited by blue light having a first peak due to blue phosphor 23 and blue light having a second peak due to blue phosphor 24. Such a white light emitting device has a high degree of freedom in designing a white light emitting device with high luminance and high color rendering, and can be provided more stably, by using a model such as that shown in Fig. 2. Also, since only one semiconductor light emitting element is used, the cost is lower.

[0045] The first phosphor 1 may be dispersed in a phosphor layer 20 that also functions as a sealant made of resin, glass, or the like that covers the purple semiconductor light emitting element (purple LED) 13, and may be housed in a package 30. In addition to resin, for example, filler 3 and additives for improving the dispersibility of the phosphors, etc. may be appropriately added to the phosphor layer 20. The package 30 and the substrate 40 may be integrally molded. This is also the case in the examples shown in Figs. 3 and 5.

[0046] Such a white light emitting device 100 does not use a combination of multiple blue semiconductor light emitting elements (blue LEDs) that satisfy a certain condition, but rather uses a first blue light SS having a first peak and a second blue light LL having a second peak emitted from a phosphor, resulting in a white light emitting device that is easy to achieve high brightness 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 as in the conventional example (FIG. 7), a power supply voltage for driving two blue semiconductor light emitting elements (blue LEDs) is required, but 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.

[0047] It is also preferable to use a semiconductor light-emitting element that emits a first blue light SS having a first peak, and a first phosphor that is excited by the first blue light emitted from the semiconductor light-emitting element and emits a second blue light LL having a second peak. In other words, this corresponds to a case where the second peak is derived from the emission of light from the first phosphor excited by the light emitted from the semiconductor light-emitting element. An example of such a white light-emitting device is shown in FIG. 3. Also, a model of the emission in the white light-emitting device of FIG. 3 is shown in FIG. 4.

[0048] The white light emitting device 200 according to the second embodiment of the present invention shown in FIG. 3 uses a blue semiconductor light emitting element (blue LED) 11 as a light source that emits a first blue light SS, and a blue phosphor 24 as a phosphor that emits a second blue light LL. The blue phosphor 24 is excited by the first blue light SS from the blue semiconductor light emitting element (blue LED) 11, and emits the second blue light LL. The second phosphor 2 (e.g., green phosphor 21, red phosphor 22) emits light by being excited by the first blue light SS from the blue semiconductor light emitting element (blue LED) 11 or the second blue light LL from the first phosphor, as in the white light emitting device 100 of FIG. 1. Such a white light emitting device 200 becomes a white light emitting device with high brightness and easy high color rendering, by a model as shown in FIG. 4. In addition, since only one semiconductor light emitting element is used, the cost is lower.

[0049] In addition, since only one blue semiconductor light-emitting element (blue LED) is used, the degree of freedom of design is higher than in the past. Furthermore, it is advantageous in terms of cost, as in the case of the white light-emitting device 100 of Fig. 1. Furthermore, there is no need to connect multiple blue semiconductor light-emitting elements (blue LEDs) in series to equalize the current flowing through them, and for example, an existing LED drive circuit with a Vf output of 2.9V can be used.

[0050] Also, two semiconductor light emitting elements, an ultraviolet LED or a purple LED and a blue LED, can be used as the semiconductor light emitting element. Specifically, it is also preferable to use a first semiconductor light emitting element that emits ultraviolet light or purple light, a first phosphor that is excited by the ultraviolet light or purple light emitted from the first semiconductor light emitting element to emit a first blue light SS having a first peak, and a second semiconductor light emitting element that emits a second blue light LL having a second peak. In other words, the first peak corresponds to the case where the first phosphor is excited by the light emitted from the semiconductor light emitting element to emit light. An example of such a white light emitting device is shown in FIG. 5. Also, a model of light emission in the white light emitting device of FIG. 5 is shown in FIG. 6.

[0051] A white light emitting device 300 according to a third embodiment of the present invention shown in Fig. 5 includes a semiconductor light emitting element (ultraviolet LED or purple LED) 13 that emits ultraviolet light or purple light as a semiconductor light emitting element, a blue phosphor 23 that is excited by the ultraviolet light or purple light emitted from the semiconductor light emitting element (ultraviolet LED or purple LED) 13 to emit a first blue light, and a blue semiconductor light emitting element (blue LED) 12 that emits a second blue light. Such a white light emitting device 300 becomes a white light emitting device with high brightness and easy high color rendering, according to a model as shown in Fig. 6.

[0052] In the white light emitting devices according to the first to third embodiments, at least one of the half width at maximum (FWMH) of the first peak of the peak wavelength P1 of the first blue light SS and the half width at maximum (FWMH) of the second peak of the peak wavelength P2 of the second blue light LL is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. If the half width at maximum of the first and / or second peak is 50 nm or less, a sufficient valley is formed between the first peak of the first blue light SS and the second peak of the second blue light LL, resulting in a white light emitting device with higher luminance and higher color rendering.

[0053] In the white light emitting devices according to the first to third embodiments described above, as shown in FIG. 9 , the valley between the first peak of the peak wavelength P1 of the first blue light SS and the second peak of the peak wavelength P2 of the second blue light LL is preferably relatively deep with respect to the average emission intensity Ip1 of the first peak and the emission intensity Ip2 of the second peak. If the emission intensity of the valley is Iv, then: 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ··· (4) It is preferable to satisfy the above condition. Generally, it is desirable for the spectrum of high color rendering light close to sunlight to be broad, but in a white light emitting device combining a semiconductor light emitting element and a phosphor, the color rendering evaluation index R9 (red) and R12 (blue) are in a trade-off relationship. If the valley depth of Iv / {(Ip1+Ip2) / 2} is 0.3 or more, the color rendering evaluation index of R12 (blue) can be more stably set to 90 or more, and if the valley depth of Iv / {(Ip1+Ip2) / 2} is 0.5 or less, the color rendering evaluation indexes R9 (red) and R12 (blue) can be more stably set to 90 or more. By satisfying the above formula (4), the color rendering of the color rendering evaluation indexes R9 (red) and R12 (blue) can be stably increased, and it becomes possible to output white light with even higher color rendering.

[0054] (First phosphor) In the white light emitting devices according to the first to third embodiments, the first phosphor is not particularly limited as long as it emits light having a peak wavelength larger than the peak wavelength of the light emitted from the semiconductor light emitting element, but it is preferable to use a quantum dot (QD) phosphor or a (Ba, Sr) 3 MgSi 2 O 8: Eu phosphor. The 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 the color rendering can be adjusted more easily. In the (Ba, Sr) 3 MgSi 2 O 8: Eu blue phosphor, the peak wavelength can be shifted to the long 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 (3) and / or (4), and the color rendering can be adjusted more easily.

[0055] (Second phosphor) In the white light emitting devices according to the first to third embodiments, the second phosphor is not particularly limited, and either an inorganic phosphor or an organic phosphor may be used. Specifically, the second phosphor may be a phosphor that is a combination of one or more of aluminate phosphors such as SAE and LuAG·YAG, and nitride phosphors such as CASN·SCASN. Preferably, a phosphor containing a LuAG phosphor or a YAG phosphor as the green phosphor and a CASN phosphor or a SCASN phosphor as the red phosphor may be used. An SAE phosphor may also be combined. This allows a white light emitting device with higher brightness and higher color rendering.

[0056] It is also preferable to provide a layer 4 containing the first phosphor between the semiconductor light emitting element and the layer containing the second phosphor 2. This results in a brighter white light emitting device.

[0057] The present specification includes the following aspects. [1]: A white light emitting device including: a semiconductor light emitting element; a first phosphor that is excited by light emitted from the semiconductor light emitting element and emits light having a peak wavelength greater than the peak wavelength of the light emitted from the semiconductor light emitting element; and a second phosphor that is excited by at least one of the light emitted from the semiconductor light emitting element and the light emitted from the first phosphor and emits light, the light emitted from the semiconductor light-emitting element and the first phosphor includes blue light having a first peak at a peak wavelength P1 and a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum; At least one of the first peak and the second peak is derived from light emission produced when the first phosphor is excited by light emitted from the semiconductor light emitting element, The peak wavelength P1 and the peak wavelength P2 are 430nm≦P1 <P2≦480nm ··· (1) P2-P1≧16 nm (2) Fulfilling When the emission intensities at the first peak and the second peak are Ip1 and Ip2, respectively, 0.5≦(Ip1 / Ip2)≦2 (3) A white light emitting device which satisfies the above requirements. [2]: the semiconductor light-emitting element emits ultraviolet light or violet light, The white light-emitting device of [1] above, wherein the first phosphor is excited by the ultraviolet light or violet light emitted from the semiconductor light-emitting element to emit blue light having the first peak and the second peak. [3]: the semiconductor light emitting element emits a first blue light having the first peak, The white light-emitting device of [1] above, wherein the first phosphor is excited by the first blue light emitted from the semiconductor light-emitting element to emit a second blue light having the second peak. [4]: The semiconductor light-emitting element includes a first semiconductor light-emitting element and a second semiconductor light-emitting element; the first semiconductor light emitting element emits ultraviolet light or violet light, the first phosphor is excited by the ultraviolet light or violet light emitted from the first semiconductor light emitting element to emit a first blue light having the first peak; The white light emitting device according to [1] above, wherein the second semiconductor light emitting element emits second blue light having the second peak. [5]: The white light emitting device according to the above [1], [2], [3] or [4], 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. [6]: In the emission spectrum, a valley is provided between the first peak and the second peak, the emission intensity of the first peak is Ip1, the emission intensity of the second peak is Ip2, and the emission intensity of the valley between the first peak and the second peak is Iv, 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 ···(4) The white light-emitting device according to the above [1], [2], [3], [4] or [5], which satisfies the above condition. [7]: The white light emitting device according to [1], [2], [3], [4], [5] or [6], wherein the first phosphor is a quantum dot phosphor. [8]: The white light emitting device according to [1], [2], [3], [4], [5] or [6], wherein the first phosphor is a (Ba,Sr)3MgSi2O8:Eu based phosphor. [9]: The white light-emitting device according to [1], [2], [3], [4], [5], [6], [7] or [8], wherein the second phosphor comprises an SAE phosphor, a LuAG-based phosphor or a YAG-based phosphor, and a CASN-based phosphor or a SCASN-based phosphor.

[10] : The white light-emitting device according to [1], [2], [3], [4], [5], [6], [7], [8] or [9], further comprising a layer containing the first phosphor between the semiconductor light-emitting element and the layer containing the second phosphor.

[0058] 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]

[0059] 1...first phosphor, 2...second phosphor, 3…filler, 4...first fluorescent layer 1; 11...first blue semiconductor light emitting element (blue LED), 12...Second blue semiconductor light emitting element (blue LED), 13... Purple semiconductor light emitting element (purple LED), 20...phosphor layer, 21...green phosphor (second phosphor), 22...red phosphor (second phosphor), 23, 24...Blue phosphor (first phosphor), 30…package, 40...Substrate, 100, 200, 300, 400...White light-emitting device. SS...blue light (first blue light), LL...blue light (second blue light), L...white light.

Claims

1. A white light emitting device including: a semiconductor light emitting element; a first phosphor that is excited by light emitted from the semiconductor light emitting element and emits light having a peak wavelength larger than the peak wavelength of the light emitted from the semiconductor light emitting element; and a second phosphor that is excited by at least one of the light emitted from the semiconductor light emitting element and the light emitted from the first phosphor and emits light, The light emitted from the semiconductor light-emitting element and the first phosphor includes blue light having a first peak at a peak wavelength P1 and a second peak at a peak wavelength P2 in a wavelength range of 430 to 480 nm of an emission spectrum, At least one of the first peak and the second peak is derived from light emission generated when the first phosphor is excited by light emitted from the semiconductor light emitting element, 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 intensities at the first peak and the second peak are Ip1 and Ip2, respectively, 0.5≦(Ip1 / Ip2)≦2... (3) A white light emitting device which satisfies the above requirements.

2. The semiconductor light emitting element emits ultraviolet light or violet light, 2. The white light-emitting device according to claim 1, wherein the first phosphor is excited by the ultraviolet light or violet light emitted from the semiconductor light-emitting element to emit blue light having the first peak and the second peak.

3. the semiconductor light emitting element emits a first blue light having the first peak, 2. The white light-emitting device according to claim 1, wherein the first phosphor is excited by the first blue light emitted from the semiconductor light-emitting element to emit a second blue light having the second peak.

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

5. 5. 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.

6. In the emission spectrum, a valley is provided between the first peak and the second peak, the emission intensity of the first peak is Ip1, the emission intensity of the second peak is Ip2, and the emission intensity of the valley between the first peak and the second peak is Iv, 0.3≦Iv / {(Ip1+Ip2) / 2}≦0.5 (4) 6. The white light emitting device according to claim 5, wherein the above condition is satisfied.

7. 7. The white light emitting device according to claim 6, wherein the first phosphor is a quantum dot phosphor.

8. The first phosphor is (Ba, Sr) ３ MgSi ２ O ８ 7. The white light emitting device according to claim 6, wherein the phosphor is a Eu-based phosphor.

9. 7. The white light emitting device according to claim 6, wherein the second phosphor includes an SAE phosphor, a LuAG-based phosphor or a YAG-based phosphor, and a CASN-based phosphor or a SCASN-based phosphor.

10. 7. The white light emitting device according to claim 6, further comprising a layer containing the first phosphor between the semiconductor light emitting element and the layer containing the second phosphor.

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