JP2021136293A - Light-emitting device - Google Patents

Abstract

To provide a light-emitting device with high light emission intensity and temperature characteristics even when a fluorescent body which is of high quality and low cost and difficult to execute excitation by the light from a blue LED.SOLUTION: A light-emitting device includes: a light-emitting device with an emission peak wavelength in a range of 380-480 nm; a first fluorescent body which is excited by the light-emitting device and has the emission peak wavelength in the first range; and a second fluorescent body which has a peak wavelength of an excitation spectrum in the first range and a peak wavelength of an emission spectrum in a second range different from the first range.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light emitting device including a light emitting element and a phosphor.

A phosphor is a material that is attracting attention from an environmental point of view because it has excellent light emitting properties and can emit light with extremely low energy. In addition, with the increasing social needs for power saving in recent years, there is also a high need for alternatives to existing lamps by taking advantage of the excellent energy saving properties of phosphors. Further, it is expected to be applied to various fields depending on the emission wavelength.

For example, since near-infrared light has high light transmission to a living body, it is also applied to an optical interference tomographic imaging device (OCT) and the like, and is expected to be applied to non-destructive measurement and the like. For example, Patent Document 1 reports the need for broad light emission in biological imaging and the like. Patent Documents 2 and 3 describe a phosphor that is excited by visible light in a wide band to emit a broad fluorescence spectrum and can emit near-infrared light.

International Publication No. 2013/01/1984 International Publication No. 2016/140029 International Publication No. 2017/159175

Optics Express Vol. 18, Issue 19, pp. 20215-20221 (2010)

By the way, most of the conventional near-infrared phosphors do not have a peak in the excitation spectrum in the blue region. Therefore, there is a problem that the luminous efficiency is poor when combined with a blue light emitting element (blue LED). For example, Patent Document 3 refers to a light emitting element incorporating a phosphor, but does not describe the details of the combination of the light emitting element and the phosphor. FIG. 1 of Patent Document 3 shows the emission spectrum and the excitation spectrum of the near-infrared emitting phosphor (see FIG. 14). In particular, when the excitation spectrum is seen, it hardly shines in blue excitation and is excited in red. It has been shown to be good to do. From this, the combination with the red light emitting element (red LED) is also common considering the excitation spectrum. However, when the red LED and the near-infrared phosphor are combined, there is a problem that the emission intensity in the near-infrared region is weak. Further, the poor temperature characteristic of the red LED affects the entire element, and there is a problem that the temperature characteristic of light emission in the near infrared region is poor. At present, there is little demand for light emitting devices using near-infrared phosphors because the light emitting intensity is weak.

In this way, the combination of the range of the emission peak of the LED and the range of the peak of the excitation spectrum of the phosphor is limited. Therefore, in the case of a phosphor that is difficult to be excited by the emission from the blue LED, the emission intensity and temperature. There is a problem that a high-quality, low-cost LED with excellent characteristics cannot be combined with a relatively easily available blue LED. For example, in a light emitting device having a light emitting peak in the near infrared region as described above, there is a problem that a light emitting device having high light emitting characteristics cannot be obtained.

The present invention has been made to solve the above problems, and even when a phosphor that is difficult to be excited by light from a high-quality, low-cost blue LED is used, the emission intensity is strong and the temperature characteristics are improved. Also aims to provide an excellent light emitting device.

The present invention has been made to achieve the above object, and a light emitting element having an emission peak wavelength in the range of 380 to 480 nm and a light emitting element excited by the light emitting element and having an emission peak wavelength in the first range. Emission including 1 phosphor and a second phosphor having a peak wavelength of an excitation spectrum in the first range and a peak wavelength of an emission spectrum in a second range different from the first range. Provide the device.

According to such a light emitting device, it is a light emitting device to which various phosphors can be applied without being limited to the peak of the excitation spectrum while using a high quality and low cost blue LED, and the light emitting intensity is strong. It is a light emitting device with excellent temperature characteristics.

At this time, in the second phosphor, the intensity of the excitation spectrum in the range of 380 to 480 nm is lower than the peak intensity of the excitation spectrum in the first range, more preferably in the first range. It can be a light emitting device having a peak intensity of less than half of the excitation spectrum.

As a result, even when a phosphor having a low excitation spectrum is combined in the region where the emission peak of the blue LED is located, the emission device has strong emission intensity and excellent temperature characteristics.

At this time, the emitted light of the light emitting device has at least a first light emitting peak and a second light emitting peak, the peak wavelength of the first light emitting peak is in the second range, and the second light emitting peak. A light emitting device having a peak wavelength of 380 to 480 nm can be used. Further, the emitted light may be a light emitting device having a third emission peak and the peak wavelength of the third emission peak is in the first range.

As a result, the light emitting device has stronger light emitting intensity and better temperature characteristics.

At this time, the light emitting device having the first range of 500 to 700 nm can be used.

As a result, the light emitting device has stronger light emitting intensity and better temperature characteristics.

At this time, the light emitting device having the second range of more than 700 nm and 2000 nm or less can be used.

As a result, the light emitting device has a light emitting peak in the near to far infrared region, which has strong light emitting intensity and excellent temperature characteristics.

At this time, the first phosphor can be a light emitting device which is a visible light emitting phosphor.

As a result, as the second phosphor, one that can be excited by light emission from the visible light emitting phosphor can be applied, so that the light emitting device has stronger emission intensity and better temperature characteristics.

At this time, the second phosphor can be a light emitting device which is a near infrared emitting phosphor.

As a result, the light emitting device has a light emitting peak in the near infrared region, which has strong light emitting intensity and excellent temperature characteristics.

At this time, at least one of the first phosphor and the second phosphor may contain a plurality of types of phosphors.

As a result, the light emitting device has stronger light emitting intensity and excellent temperature characteristics.

At this time, the light output of 781 to 1042 nm when a current of 65 mA is passed through the light emitting element can have a light emitting amount of 15.0 mW or more.

As described above, the light emitting device according to the present invention has excellent light emitting amount and excellent temperature characteristics especially in the near infrared region.

As described above, according to the light emitting device of the present invention, various phosphors can be applied without being limited to the peak position of the excitation spectrum while using a high quality and low cost blue LED. It is a light emitting device with strong light emitting intensity and excellent temperature characteristics.

An example of the light emitting device according to the present invention is shown. The light output evaluation result of Comparative Example 1-6 is shown. The emission spectrum of the light emitting device produced in Comparative Example 1-4 is shown. The light output evaluation result of Example 1-5 is shown. The emission spectrum of the light emitting device produced in Example 1-3 is shown. The emission spectrum of the light emitting device produced in Examples 4 and 5 is shown. The light output evaluation result of Example 6-12 is shown. The emission spectrum of the light emitting device produced in Example 6-9 is shown. The emission spectrum of the light emitting device produced in Example 10-12 is shown. The light output evaluation results of Examples 9 and 13-15 are shown. The emission spectrum of the light emitting device produced in Examples 9 and 13-15 is shown. The emission spectra of Example 9 and Comparative Example 3 are shown. The temperature characteristics of the emission intensity of Example 9 and Comparative Example 3 are shown. It is a citation of FIG. 1 of Patent Document 3, and shows an excitation spectrum and an emission spectrum of a near-infrared emission phosphor.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

As described above, there is a demand for a light emitting device having strong light emission intensity and excellent temperature characteristics even when a phosphor that is difficult to be excited by light from a blue LED, which is high quality and low cost, is used. rice field.

As a result of diligent studies on the above problems, the present inventors have a light emitting element having a emission peak wavelength in the range of 380 to 480 nm, and a first light emitting element excited by the light emitting element and having an emission peak wavelength in the first range. And a second phosphor having a peak wavelength of the excitation spectrum in the first range and a peak wavelength of the emission spectrum in a second range different from the first range. As a result, even a phosphor that is difficult to be excited by light from a blue LED can be combined with a high-quality, low-cost blue LED that has strong emission intensity and excellent temperature characteristics, and has strong emission intensity and temperature characteristics. The present invention has been completed by finding that it is possible to provide an excellent light emitting device and to provide a light emitting device to which various phosphors can be applied without being limited to the peak of the excitation spectrum.

Hereinafter, description will be made with reference to the drawings. In addition, when the numerical value range is expressed as "380-480 nm" in this specification, it means "380 nm or more and 480 nm or less".

(Light emitting device)
FIG. 1 shows an example of a light emitting device 100 according to the present invention. The light emitting device 100 according to the present invention absorbs a part of the light emitted from the light emitting element 10 arranged on the substrate 40 and the light emitting element 10 and converts the light L into light L having a wavelength different from the light emitting wavelength of the light emitting element 10. It contains the phosphor 1. The phosphor 1 includes a first phosphor 1a and a second phosphor 1b, and these phosphors 1a and 1b can also be used as an encapsulant made of resin, glass, or the like that coats the light emitting element 10. It is dispersed in a functional phosphor layer 20 and housed in a package 30. In addition to the resin, for example, a filler 2 and an additive for enhancing the dispersibility of the phosphor 1 and the like can be appropriately added to the phosphor layer 20. Further, the package 30 and the substrate 40 may be integrally molded.

(Light emitting element)
As the light emitting element 10, one having a light emitting peak wavelength in the range of 380 to 480 nm is used. Such a light emitting element emits blue light, and a high quality and low cost one is relatively easily available.

(First and second phosphors)
As the first phosphor 1a, one that is excited by a light emitting element 10 having an emission peak wavelength in the range of 380 to 480 nm and has an emission peak wavelength in the first range in the emission spectrum is used. At this time, as the first phosphor, a visible light emitting phosphor can also be adopted.

Further, as the second phosphor 1b, one having a peak wavelength of the excitation spectrum in the first range and a peak wavelength of the emission spectrum in a second range different from the first range is used. At this time, as the second phosphor, the intensity of the excitation spectrum in the range of 380 to 480 nm is preferably lower than the peak intensity of the excitation spectrum in the first range, and one having less than half is more preferably used. be able to. Even those having no peak in the range of 380 to 480 nm in the excitation spectrum can be used. Further, as the second phosphor, a near-infrared emitting phosphor can also be adopted.

As described above, in the light emitting device according to the present invention, the intensity of the excitation spectrum in the range of 380 to 480 nm is low, in other words, it is difficult to be excited by the light from the blue LED, and the emission intensity is low when combined with the blue LED. Even when the second phosphor 1b is used, by using the above-mentioned first phosphor 1a together, a blue LED can be used to obtain a light emitting device having strong light emission intensity and excellent temperature characteristics. can do. Further, it becomes possible to use the second phosphor 1b having various emission peak wavelengths, and the applicable range becomes wide.

Further, at least one of the first phosphor and the second phosphor may contain a plurality of types of phosphors. As a result, the emission wavelength can be easily controlled and the emission characteristics can be improved.

Further, the emitted light of the light emitting device according to the present invention has at least a first light emitting peak and a second light emitting peak, the peak wavelength of the first light emitting peak is in the second range, and the second light emitting peak. It can be assumed that the peak wavelength of the light emission peak is in the range of 380 to 480 nm, or that the light emitting peak has a third emission peak and the peak wavelength of the third emission peak is in the first range. Such a light emitting device has a stronger light emitting intensity and is also excellent in temperature characteristics.

Further, in the light emitting device according to the present invention, if the first range is 500 to 700 nm, a second phosphor 1b excited by visible light can be used. If the second range is more than 700 nm and 2000 nm or less, the near-infrared light emitting device can be used. In particular, the conventional near-infrared light emitting device is difficult to combine with a blue LED, has weak light emitting intensity, and is inferior in temperature characteristics. However, according to the present invention, high light emitting intensity, high quality, and low cost are near. An infrared light emitting device can be obtained.

Further, the light emitting device according to the present invention can provide a light emitting device having a light emitting amount of 15.0 mW or more at an optical output of 781 to 1042 nm when a current of 65 mA is passed through the light emitting element.

Hereinafter, the present invention will be described in detail with reference to examples, but this does not limit the present invention.

(Comparative Example 1)
_{CaCuSi 4} O ₁₀ (hereinafter, "CCSO") described in Patent Document 3 as an AlGaInP-based red chip having an emission peak wavelength of 615 nm and a near-infrared phosphor (hereinafter, also referred to as "NIR phosphor"). A near-infrared light emitting device was manufactured using a phosphor (abbreviated as). Aerosil was used to prevent the settling of the thermosetting silicone resin and the phosphor. The compounding ratio is shown below. Since the amount of the phosphor is 10% with respect to the silicone resin, the phosphor concentration is set to 10%. The formula for calculating the phosphor concentration is (fluorescent concentration) = (fluorescent weight) / (fluorescent weight + silicone resin weight) × 100.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
CCSO phosphor 0.1111g

(Comparative Example 2-6)
Using the same material as in Comparative Example 1, the amount of NIR phosphor was changed to prepare a near-infrared light emitting device of Comparative Example 2-6. The conditions of Comparative Example 1-6 are shown in Table 1.

The evaluation of the near-infrared light emitting device was performed using an integrating sphere of Instrument System CAS 140CT ISP250-211. The current flowing through the near-infrared light emitting device was 65 mA, and the emission spectrum of 380 to 1042 nm was measured. Moreover, since near-infrared light does not have luminosity factor, the light output was evaluated by mW. The amount of light emitted in the near infrared was 781 to 1042 nm, and was shown in mW. Table 2 and FIG. 2 show the light output evaluation results of Comparative Example 1-6. Further, the emission spectrum of the produced light emitting device is shown in FIG.

As shown in Table 2 and FIG. 2, in the light emitting device in which the red chip and the NIR phosphor are combined, the maximum amount of light emitted is about 14.9 mW (fluorescent concentration 30 to 40%) even if the phosphor concentration is adjusted. )was. Further, as shown in FIG. 3, in the light emitting device of Comparative Example 1-6, those having light emitting peaks at 600 to 650 nm and 850 to 950 nm were obtained.

(Example 1)
An InGaN-based blue chip having an emission peak wavelength of 452 nm, a (Sr, Ca) AlSiN ₃ : Eu2 + (hereinafter abbreviated as “SCASSN”) phosphor which is a red phosphor having an emission peak wavelength of 607 nm, and the above-mentioned CCSO phosphor. A near-infrared light emitting device was manufactured using the above. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
SCASN phosphor (607 nm) 0.3046 g
CCSO phosphor 0.1305g

(Example 2)
A near-infrared light emitting device was produced by using an InGaN-based blue chip having an emission peak wavelength of 452 nm, a SCASEN phosphor having an emission peak wavelength of 613 nm, and the above-mentioned CCSO phosphor. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
SCASN phosphor (613 nm) 0.3046 g
CCSO phosphor 0.1305g

(Example 3)
A near-infrared light emitting device was produced by using an InGaN-based blue chip having an emission peak wavelength of 452 nm, a SCASEN phosphor having an emission peak wavelength of 622 nm, and the above-mentioned CCSO phosphor. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
SCASN phosphor (622 nm) 0.3046 g
CCSO phosphor 0.1305g

(Example 4)
A near-infrared light emitting device was produced using an InGaN-based blue chip having an emission peak wavelength of 452 nm, a SCASEN phosphor having an emission peak wavelength of 632 nm, and the above-mentioned CCSO phosphor. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
SCASN phosphor (632 nm) 0.3046 g
CCSO phosphor 0.1305g

(Example 5)
A near-infrared light emitting device is provided by using an InGaN-based blue chip having an emission peak wavelength of 452 nm, a CaAlSiN3: Eu2 + (hereinafter abbreviated as CASN) phosphor which is a red phosphor having an emission peak wavelength of 650 nm, and the above-mentioned CCSO phosphor. Made. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
CASN phosphor (650 nm) 0.3046 g
CCSO phosphor 0.1305g

Tables 3 and 4 show the light output evaluation results of Example 1-5. The emission spectra of the manufactured light emitting device are shown in FIGS. 5 and 6.

As shown in Tables 3 and 4, in each of Examples 1-5, it was possible to obtain an emission amount of 15.0 mW or more, which was superior to that of Comparative Example. Further, as shown in FIGS. 5 and 6, in the light emitting device of Example 1-5, one having a light emitting peak at 380 to 480 nm, 500 to 700 nm, more than 700 nm, particularly 800 to 2000 nm was obtained. Further, it was found that the emission peak wavelength of the red phosphor is particularly good at 622 nm.

Next, the emission peak wavelength of the red phosphor was fixed at 622 nm, and the ratio of the red phosphor and the NIR phosphor was changed for examination.

(Example 6)
A near-infrared light emitting device was produced using an InGaN-based blue chip having an emission peak wavelength of 452 nm, a SCASEN phosphor having an emission peak wavelength of 622 nm, and the above-mentioned CCSO phosphor. Thermosetting silicone resin and Aerosil were used to prevent precipitation of the phosphor. The compounding ratio is shown below.
Silicone resin A (main agent) 0.5000g
Silicone resin B (hardener) 0.5000 g
Aerosil 0.0150g
SCASEN phosphor (622 nm) 0.0670 g
CCSO phosphor 0.6030g

(Example 7-12)
In Example 6, a near-infrared light emitting device was produced by changing the ratio of the red phosphor (SCASN phosphor) and the NIR phosphor (CCSO phosphor), and evaluated.

Tables 4 and 7 show the light output evaluation results of Examples 6-12. In Table 4, the numerical values of the red phosphor and the NIR phosphor are the ratios when the total is 100. The emission spectra of the manufactured light emitting device are shown in FIGS. 8 and 9.

As shown in Table 4 and FIG. 7, in the light emitting device of Example 6-12, all the results showed superior characteristics as compared with the comparative example. Further, as shown in FIGS. 8 and 9, even in the light emitting device of Example 6-12, one having a light emitting peak at 380 to 480 nm, 500 to 700 nm, more than 700 nm, particularly 800 to 2000 nm was obtained. In particular, it was found that the ratio of the red phosphor to the NIR phosphor was good at 50:50.

(Examples 9, 13-15)
Next, the study was conducted by changing the amount of the phosphor (fluorescent concentration:%) with respect to the silicone resin. The ratio of the red phosphor to the NIR phosphor at this time was 50:50 (corresponding to Example 9 above).

Table 5 and FIG. 10 show the evaluation results of Examples 13-15 together with the results of Example 9 above. Further, the emission spectrum of the produced light emitting device is shown in FIG.

As shown in Table 5 and FIG. 10, all the results of the light emitting device of Examples 13-15 showed superior characteristics to those of the comparative example. It was found that 50% of the amount of the phosphor (fluorescent concentration) with respect to the silicone resin had the highest output. Further, as shown in FIG. 11, even in the light emitting device of Example 13-15, one having a light emitting peak at 380 to 480 nm, 500 to 700 nm, more than 700 nm, particularly 800 to 2000 nm was obtained.

Based on the above examination results, a comparison was made between Comparative Example 3 having the highest output among the comparative examples in which the red LED and the NIR phosphor were combined, and Example 9 in which the blue LED, the red phosphor and the NIR phosphor were combined. rice field. The results are shown in Table 6 and FIG. It can be seen that the combination of the blue LED, the red phosphor, and the NIR phosphor emits stronger light in the near infrared region.

Moreover, the temperature characteristics of Comparative Example 3 and Example 9 were measured. The amount of light emitted at 25 ° C. was set to 100%. The results are shown in FIG. As can be seen from FIG. 13, it can be seen that the temperature characteristics of Example 9 are excellent (the decrease in emission intensity due to the temperature rise is suppressed). This is because the difference in temperature characteristics between the red element and the blue element has a great influence.

In the examples, CaCuSi ₄ O ₁₀ was used as the near-infrared phosphor, but the present invention can also be applied to phosphors in other regions. For example, the present invention can be applied to other near-infrared emitting phosphors having a low excitation intensity in the blue region due to the shape of the excitation spectrum. As such a near-infrared emitting phosphor, FIG. 1 of Non-Patent Document 1. _{La 3} Ga ₅ GeO ₁₄ : Cr and Zn also shown in (a) can also be used. Although SCANS was used as the red phosphor, the present invention can also be applied to _{CASN, Sr 2} Si ₅ N ₈ : Eu2 +, K ₂ SiF _{6: Mn4 +, and other materials.}

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. Is included in the technical scope of.

1 ... Fluorescent material, 1a ... 1st fluorescent material, 1b ... 2nd fluorescent material, 2 ... Filler,
10 ... light emitting element, 20 ... phosphor layer, 30 ... package, 40 ... substrate, L ... light,
100 ... Light emitting device.

Claims (11)

A light emitting element whose emission peak wavelength is in the range of 380 to 480 nm, and
A first phosphor excited by the light emitting element and having a emission peak wavelength in the first range,
A light emitting device characterized in that the peak wavelength of the excitation spectrum is in the first range and the peak wavelength of the emission spectrum includes a second phosphor in a second range different from the first range. .. The light emission according to claim 1, wherein the second phosphor has an excitation spectrum intensity in the range of 380 to 480 nm lower than the peak intensity of the excitation spectrum in the first range. Device. According to claim 1 or 2, the second phosphor has an excitation spectrum intensity in the range of 380 to 480 nm which is half or less of the peak intensity of the excitation spectrum in the first range. The light emitting device described. The emitted light of the light emitting device has at least a first light emitting peak and a second light emitting peak, the peak wavelength of the first light emitting peak is in the second range, and the peak wavelength of the second light emitting peak is The light emitting device according to any one of claims 1 to 3, wherein the light emitting device has a wavelength of 380 to 480 nm. The light emitting device according to claim 4, wherein the emitted light further has a third light emitting peak, and the peak wavelength of the third light emitting peak is in the first range. The light emitting device according to any one of claims 1 to 5, wherein the first range is 500 to 700 nm. The light emitting device according to any one of claims 1 to 6, wherein the second range is more than 700 nm and 2000 nm or less. The light emitting device according to any one of claims 1 to 7, wherein the first phosphor is a visible light emitting phosphor. The light emitting device according to any one of claims 1 to 8, wherein the second phosphor is a near infrared emitting phosphor. The light emitting device according to any one of claims 1 to 9, wherein at least one of the first phosphor and the second phosphor contains a plurality of types of phosphors. The light emission according to any one of claims 1 to 10, wherein the light output of 781 to 1042 nm when a current of 65 mA is passed through the light emitting element has a light emission amount of 15.0 mW or more. Device.

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