Light-emitting device and electronic device

Abstract

To provide a light emitting device for emitting high-output light with high ratio of a near-infrared fluorescent component under excitation by high-output light and high-density light, and an electronic apparatus using the device.SOLUTION: A light emitting device 1 includes: a light source 2 for emitting primary light 6; and first phosphors 4 for absorbing the primary light 6 so as to convert it into first wavelength conversion light 7 with a longer wavelength than that of the primary light 6. The primary light 6 has rated optical output of 3 W or more. The first wavelength conversion light 7 includes fluorescence based on electronic energy transfer of Cr3+ and has a fluorescence spectrum which has the maximum fluorescence intensity value in a wavelength range of a wavelength of more than 710 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a light-emitting device and an electronic device. [Background technology]

[0002] Conventionally, Cr 3+ Light-emitting devices using activated phosphors (Configuration (P)) are known. Light-emitting devices equipped with an LED chip that emits incoherent light and a near-infrared phosphor (Configuration (Q)) are also known. Furthermore, light-emitting devices equipped with a light source that emits coherent laser light such as a laser diode and a phosphor that emits red fluorescent components (hereinafter referred to as "red phosphor") (Configuration (R)) are also known.

[0003] For example, Patent Document 1 describes a light-emitting device that satisfies the features (P) and (Q), which is a Cr 3+ and Ce 3+ The YAG phosphor is co-activated with YAlO. 12 :Cr 3+ ,Ce 3+ , Lu3Al5O 12 :Cr 3+ ,Ce 3+ , Y3(Al,Ga)5O 12 :Cr 3+ ,Ce 3+ , (Y,Gd)3Al5O 12 :Cr 3+ ,Ce 3+ etc. are used.

[0004] Furthermore, Patent Document 2 discloses an illumination light source for plant cultivation that uses a phosphor having a fluorescence peak in the wavelength region of 700 to 760 nm, which corresponds to the light absorption spectrum of a pigment protein (phytochrome) that plants have, as a light-emitting device that satisfies the features (P) and (Q). Specifically, Patent Document 2 discloses Gd3Ga5O 12 :Cr 3+An illumination light source for plant growth has been disclosed that packages a phosphor and a blue LED. With this illumination light source, the wavelength range of 700 to 760 nm, where the fluorescence peak of the phosphor exists, corresponds to the light absorption spectrum of a pigment protein (phytochrome), and therefore it is possible to control the growth and differentiation of plants. Furthermore, Patent Document 6 discloses an infrared light-emitting device that emits light over a wide band in a wavelength range where the light receiving sensitivity of a Si photodiode detector is high.

[0005] Furthermore, Patent Document 3 discloses a medical examination device that outputs a reflected image or a transmitted image of a near-infrared light component irradiated onto biological tissue as a light emitting device that satisfies configuration (Q). This medical examination device uses, as the near-infrared light component, a fluorescent component emitted by a phosphor containing rare earth elements Nd and Yb as an activator.

[0006] In addition, Patent Document 4 describes a light-emitting device that satisfies the configuration (R), which is a laser diode and a Ce 3+ Various laser-based lighting devices have been disclosed that include a red phosphor activated by a laser.

[0007] The light emitting devices described in Patent Documents 1 to 3 and 6, which do not satisfy the structure (R), are intended to simply obtain output light containing near-infrared light components suitable for plant growth, etc., with the aim of providing a lighting device for plant growth, etc. In other words, the light emitting devices described in Patent Documents 1 to 3 and 6 do not solve the problem of saturation of the light output of the phosphor, which is inherent to light emitting devices that use laser light. Therefore, the light emitting devices described in Patent Documents 1 to 3 and 6 use Cr 3+ The shape of the fluorescent spectrum emitted by the activated phosphor is not limited to a great extent.

[0008] Furthermore, as a first light-emitting device using a near-infrared phosphor, a lighting device mainly for plant growth is known. However, this first light-emitting device is simply intended to obtain output light containing a near-infrared light component suitable for plant growth, and does not solve the problem of saturation of the light output of the phosphor when the phosphor is excited with high-density light.

[0009] Furthermore, as a second light-emitting device using a near-infrared phosphor, an illumination device for optical coherence tomography (OCT) that outputs a reflected image or a transmitted image of a near-infrared light component irradiated onto biological tissue is known. However, this second light-emitting device relates to a medical illumination device and does not solve the problem of reduced energy conversion efficiency due to variations in the absorption wavelength of drugs that are inherent in medical techniques using fluorescence imaging or photodynamic therapy.

[0010] In addition, as a light-emitting device using laser light, rare earth ions (Ce 3+ and Eu 2+ There is known a light emitting device that obtains visible light output light by using a phosphor activated with Cr. 3+ It does not produce high-power near-infrared light based on electron energy transitions.

[0011] In light-emitting devices that excite phosphors with laser light, there has been a problem that the fluorescent output of the phosphors becomes saturated. Conventionally, in order to suppress the saturation of the fluorescent output, as shown in Patent Documents 4 and 5, for example, Ce 3+ and Eu 2+ It has been considered essential to use phosphors with short decay times (10 μs or less) that exhibit fluorescence based on parity-allowed transitions such as Ce. 3+ It has been considered preferable to use activated phosphors. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-121226 [Patent Document 2] International Publication No. 2010 / 053341 [Patent Document 3] Patent No. 5812461 [Patent Document 4] Patent No. 6206696 [Patent Document 5] International Publication No. 2016 / 092743 [Patent Document 6] International Publication No. 2018 / 207703 Summary of the Invention [Problem to be solved by the invention]

[0013] However, in light-emitting devices that excite phosphors with laser light, the near-infrared light components required for medical and sensing applications are generated using Ce. 3+ Activated phosphor and Eu 2+ When attempting to achieve this using activated phosphors, the following problem arises: the development of phosphors is difficult due to the limited range of materials available for use in the phosphors and the large temperature quenching, making it impossible to obtain a light-emitting device that emits near-infrared light components.

[0014] The present disclosure has been made to solve such problems. The present disclosure is directed to a Cr ZnO SiO 2 emitting fluorescence with a long decay time (10 μs or more) based on a parity-forbidden transition. 3+ This was made possible by discovering that, contrary to conventional technical wisdom, when a phosphor using this as an activator is used, saturation of the fluorescent output is unlikely to occur even under high-density laser light excitation.

[0015] The above findings are surprising and quite different from the conventional technical common sense that the use of a phosphor with a short decay time (less than 10 μs) is essential to suppress saturation of the fluorescent output.

[0016] The present disclosure aims to provide a light-emitting device that emits high-output light with a high proportion of near-infrared fluorescent components when excited by high-density laser light, and an electronic device using the same. [Means for solving the problem]

[0017] In order to solve the above problems, a light emitting device according to a first aspect of the present disclosure is a light emitting device including a light source that emits primary light and a first phosphor that absorbs the primary light and converts it into first wavelength-converted light having a longer wavelength than the primary light, wherein the primary light has a rated optical output of 3 W or more, and the first wavelength-converted light is a Cr 3+ The fluorescence spectrum of the first wavelength-converted light has a maximum fluorescence intensity in a wavelength region exceeding 710 nm.

[0018] A light emitting device according to a second aspect of the present disclosure is a light emitting device including a light source that emits primary light and a first phosphor that absorbs the primary light and converts it into first wavelength-converted light having a longer wavelength than the primary light, wherein the optical density of the primary light is 0.5 W / mm 2 and the first wavelength-converted light is Cr 3+ The fluorescence spectrum of the first wavelength-converted light has a maximum fluorescence intensity in a wavelength region exceeding 710 nm.

[0019] An electronic device according to a third aspect of the present disclosure is characterized by including the light emitting device according to the first or second aspect of the present disclosure. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view showing an example of a light emitting device according to a first embodiment. [Figure 2] FIG. 10 is a schematic cross-sectional view showing an example of a light emitting device according to a second embodiment. [Figure 3] FIG. 10 is a schematic cross-sectional view showing an example of a light emitting device according to a third embodiment. [Figure 4] FIG. 10 is a schematic cross-sectional view showing an example of a light emitting device according to a fourth embodiment. [Figure 5] FIG. 1 shows the electronic energy levels of Cr3+. [Figure 6] 1 is a diagram illustrating a schematic configuration of an endoscope according to an embodiment. [Figure 7] 1 is a diagram schematically illustrating a configuration of an endoscope system according to an embodiment. [Figure 8] 1 is a graph showing the relationship between wavelength and PL intensity. [Figure 9] 1 is a graph showing the relationship between the attenuation rate and the PL intensity. [Figure 10] 1 is a graph showing the relationship between excitation light power density and PL intensity. DETAILED DESCRIPTION OF THE INVENTION

[0021] The light emitting device according to the present embodiment will be described below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0022] [Light-emitting device] Light emitting devices 1, 1A, 1B, and 1C according to the present embodiment are shown in Figs. 1 to 4. Fig. 1 is a schematic cross-sectional view showing an example of a light emitting device according to a first embodiment. Fig. 2 is a schematic cross-sectional view showing an example of a light emitting device according to a second embodiment. Fig. 3 is a schematic cross-sectional view showing an example of a light emitting device according to a third embodiment. Fig. 4 is a schematic cross-sectional view showing an example of a light emitting device according to a fourth embodiment.

[0023] 1 to 4, the light emitting devices 1, 1A, 1B, and 1C according to the present embodiment are examples of a medical light emitting device. As shown in FIG. 1 to FIG. 4, the light emitting devices 1, 1A, 1B, and 1C each include a light source 2 and a first phosphor 4.

[0024] In the light emitting devices 1 and 1B, the first phosphor 4 is contained in the wavelength converter 3, and in the light emitting devices 1A and 1C, the first phosphor 4 is contained in the wavelength converter 3A. Therefore, the light emitting devices 1 and 1B include a light source 2 and a wavelength converter 3 containing the first phosphor 4. In addition, the light emitting devices 1A and 1C include a light source 2 and a wavelength converter 3A containing the first phosphor 4.

[0025] In the light emitting devices 1, 1A, 1B, and 1C, when primary light 6 emitted from the light source 2 is incident on the wavelength converter 3, 3A, the phosphors such as the first phosphor 4 contained in the wavelength converter 3, 3A emit fluorescence. 3+ The wavelength-converted light emitted from the photodetector includes fluorescence based on the electron energy transition of the above-mentioned compound, and has a maximum fluorescence intensity in a wavelength region exceeding 710 nm.

[0026] The wavelength converter 3 of the light emitting device 1 shown in Fig. 1 and the wavelength converter 3A of the light emitting device 1A shown in Fig. 2 are configured to receive primary light 6 on the front surface 3a and emit fluorescence from the back surface 3b. The wavelength converter 3 of the light emitting device 1B shown in Fig. 3 and the wavelength converter 3A of the light emitting device 1C shown in Fig. 4 are configured to receive primary light 6 on the front surface 3a and emit fluorescence from the same front surface 3a.

[0027] The light emitting devices 1, 1A, 1B, and 1C emit first wavelength-converted light that contains more broad spectral components with a maximum fluorescence intensity in a wavelength range exceeding 710 nm than linear spectral components with a maximum fluorescence intensity in the wavelength range of 680 to 710 nm. Therefore, the light emitting devices 1, 1A, 1B, and 1C are point light source light emitting devices that contain a large amount of near-infrared components.

[0028] The above linear spectrum component is Cr 3+ of, 2 T1 and 2 E → 4 The broad spectrum component is a long-lasting light component based on the electron energy transition (spin-forbidden transition) of A2. 4 T2 → 4 This is a short-lasting light component based on the electron energy transition (spin-allowed transition) of A2. 3+ The mechanism of fluorescence due to the light emitting devices 1, 1A, 1B and 1C will be described below.

[0029] [First embodiment] A light emitting device 1 according to a first embodiment will be described.

[0030] (light source) The light source 2 emits primary light 6. As the primary light 6, laser light is used. As the laser light, for example, laser light including at least one of cool light having a maximum fluorescence intensity within a wavelength range of 400 nm or more and less than 500 nm and warm light having a maximum fluorescence intensity within a wavelength range of 570 nm or more and less than 660 nm is used. As the cool light, preferably light having a maximum fluorescence intensity within a wavelength range of 430 nm or more and less than 480 nm is used. As the warm light, preferably light having a maximum fluorescence intensity within a wavelength range of 590 nm or more and less than 640 nm is used.

[0031] When a laser beam containing at least one of the above-mentioned cool color light and the above-mentioned warm color light is used as the primary light 6, the laser beam 3+ The primary light 6 is efficiently absorbed by the first phosphor 4 activated with Cr, and efficiently wavelength-converted into the first wavelength-converted light 7. Therefore, in the light-emitting device 1 in which laser light containing at least one of the above cool color light and the above warm color light is used as the primary light 6, Cr 3+ It is possible to emit output light having a high proportion of fluorescent components based on the electron energy transition.

[0032] As the light source 2, a cool light laser element that emits laser light of the above-mentioned cool light color or a warm light laser element that emits laser light of the above-mentioned warm light color is used. As the cool light laser element, a blue laser element that emits blue laser light is preferably used. As the warm light laser element, a red laser element that emits red laser light is preferably used. When the light source 2 is a cool light laser element or a warm light laser element, the phosphor in the wavelength converter 3, 3A is excited with high efficiency, allowing the light emitting devices 1, 1A, 1B, and 1C to emit high-power near-infrared light.

[0033] Among cool light laser elements, blue laser elements are easily available as highly efficient and high-output laser elements. Therefore, using a blue laser element as the light source 2 is preferable for achieving high output of the light emitting device. Furthermore, among warm light laser elements, red laser elements have a small energy difference with near-infrared light components, and energy loss due to wavelength conversion is small. Therefore, using a red laser element as the light source 2 is preferable for achieving high efficiency of the light emitting device.

[0034] For example, a surface-emitting laser diode is used as the light source 2. The light source 2 is a solid-state light-emitting element having a rated optical output of typically 1 W or more, preferably 3 W or more. When the rated optical output of the light source 2 is within the above range, it emits high-power primary light 6, allowing the light-emitting device 1 to have a high output.

[0035] There is no particular upper limit to the rated optical output. The output of the light source 2 can be increased by configuring the light source 2 with a plurality of solid-state light-emitting elements. However, considering practicality, the rated optical output of the light source 2 is usually less than 10 kW, and preferably less than 3 kW.

[0036] The light density of the primary light 6 irradiated onto the first phosphor 4 is typically 0.5 W / mm 2 More than 3W / mm 2 More than 10 W / mm 2 More than 30 W / mm 2 When the light density of the primary light 6 is within the above range, the first phosphor 4 is excited by the high-density light, and the light emitting device 1 is able to emit high-power fluorescent components. Note that with the future trend toward higher power LEDs, it is expected that the light density will exceed 0.5 W / mm 2 If a high-power LED exceeding this limit is developed, it can be used in the same way as the laser.

[0037] (wavelength converter) The wavelength converter 3 includes a first phosphor 4 and a sealing material 5. In the wavelength converter 3, the first phosphor 4 is contained in the sealing material 5.

[0038] <First phosphor> The first phosphor 4 is a phosphor that absorbs the primary light 6 and converts it into first wavelength-converted light 7 having a longer wavelength than the primary light 6. The first phosphor 4 absorbs the primary light 6 and converts it into Cr 3+ The first wavelength-converted light 7 includes fluorescence based on the electron energy transition of Cr. 3+ This includes fluorescence based on the electron energy transition of Cr 3+ Fluorescence based on electron energy transition is 4 T2 → 4 This refers to fluorescence based on the electron energy transition (spin-allowed transition) of A2.

[0039] Below, Cr 3+ Figure 5 shows the electron energy transition of Cr. 3+ Specifically, FIG. 5 shows the electronic energy levels of hexacoordinated Cr. 3+ , Mn 4+ This is the Tanabe-Sugeno diagram that applies to the following:

[0040] The horizontal axis of Figure 5 is the value of Dq, which indicates the magnitude of the ligand field splitting, divided by B, the Racah parameter, which indicates the strength of the electrostatic repulsion between electrons. 3+ This can be understood as an index showing the strength of the ligand field received from the surrounding ligands in the crystal. 3+ Examples of the ligands around the atom include oxygen ions.

[0041] The vertical axis of Figure 5 is the energy E from the ground state divided by the Racah parameter B. 3+ It can be understood as an index of the magnitude of the electronic energy of the excited state formed by the three 3d electrons that make up the electron cloud of the outermost shell of an atom, i.e., an index of the energy difference between the excited state formed by the three 3d electrons and the ground state.

[0042] According to Figure 5, the Cr in the phosphor crystal 3+It can be seen that the electron energy of the excited state formed by the electrons in the 3d orbital of Cr takes several discrete states. 3+ The state of electronic energy formed by the electrons of changes depending on the type, number, and arrangement of surrounding ligands, the distance to the ligands, etc., and as a result, the energy difference between the excited state and the ground state changes. Furthermore, according to Figure 5, it can be seen that each of the electronic energies of the above excited states, which take several discrete states, behaves differently depending on the ligand field. 2 E and 4 T2 and 4 Symbols such as A2 are Cr 3+ are well-known symbols that represent each of the discrete electronic energy states formed by the three electrons in the 3d orbital of an atom.

[0043] Here, the electron energy transition accompanying fluorescence is usually the lowest excited state ( 2 T1 and 2 E or 4 T2) to the ground state (in Figure 5 4 A2) in the crystal. 3+ When the strength of the ligand field is strong (when the value on the horizontal axis in Figure 5 is large), Cr 3+ teeth 2 T1 and 2 From E 4 It can be seen that the fluorescence is due to the electron energy transition to A2. Also, according to Figure 5, when the strength of the ligand field is weak (when the value on the horizontal axis in Figure 5 is small), 4 From T2 4 It can be seen that the first phosphor 4 exhibits fluorescence due to the latter electron energy transition.

[0044] In addition, 2 T1 and 2 From E 4 As can be seen from Figure 5, the energy difference of the electron energy transition to A2 does not change significantly even if the strength of the ligand field changes, so the fluorescence spectrum becomes linear.

[0045] on the other hand, 4 From T2 4 As can be seen from FIG. 5, when the strength of the ligand field changes, the energy difference of the electron energy transition to A2 changes significantly, resulting in a broad fluorescence spectrum. The fluorescence spectrum of the first phosphor 4 is as follows: 4 From T2 4 This is due to the electron energy transition (spin-allowed transition) to A2, resulting in a broad shape.

[0046] In addition, Cr 3+ 3D electron 2 T1 and 2 From E 4 The energy transition between energy levels of the electron energy transition to A2 is a parity-forbidden transition, so the fluorescence decay time is long, from 100 μs to less than 50 ms. 3+ The decay time of fluorescence based on Ce exhibits parity-allowed transitions. 3+ and Eu 2+ However, the decay time of Cr is longer than that of Cr (less than 10 μs). 3+ of 4 From T2 4 Since the electron energy transition to A2 is a spin-allowed transition between two states with the same spin, the decay time is relatively short, around 100 μs.

[0047] Cr exhibits fluorescence due to such parity-forbidden (spin-allowed) electron energy transitions. 3+ The activated phosphor is Eu, which exhibits fluorescence due to parity-allowed electron energy transitions. 2+ The present disclosure provides Cr fluorescing phosphors that exhibit fluorescence due to parity-forbidden electron energy transitions. 3+ The activated phosphor is Eu 2+ This was made possible by discovering that, despite the fact that it exhibits a much longer decay characteristic than activated phosphors, the saturation of the fluorescent output is surprisingly small.

[0048] The first phosphor 4 is a phosphor in which the first wavelength-converted light 7 is converted into Cr 3+Since the fluorescence is based on the spin-allowed electron energy transition of the first wavelength-converted light 7, the first wavelength-converted light 7 emits fluorescence that satisfies at least one of the following properties (A) to (D). The first wavelength-converted light 7 may emit fluorescence that satisfies two or more of the properties (A) to (D).

[0049] [Characteristics (A)] Characteristic (A) is a characteristic in which the fluorescence spectrum of the first wavelength-converted light 7 has a maximum fluorescence intensity in a wavelength region exceeding 710 nm. Here, the maximum fluorescence intensity refers to the maximum fluorescence intensity of the peak in the fluorescence spectrum that exhibits the maximum fluorescence intensity. The fluorescence spectrum of the first wavelength-converted light 7 has a maximum fluorescence intensity in a wavelength region exceeding preferably 730 nm, more preferably exceeding 750 nm.

[0050] A light emitting device in which the fluorescence spectrum of the first wavelength-converted light 7 has a maximum fluorescence intensity in a wavelength region exceeding 710 nm, ie, satisfies characteristic (A), can easily provide a point light source containing a large amount of near-infrared components.

[0051] Furthermore, a light emitting device that satisfies characteristic (A) is suitable as a medical light emitting device because the fluorescence spectrum of the first wavelength converted light 7 has a maximum fluorescence intensity in a wavelength range exceeding 710 nm, which is a wavelength range suitable for medical use.

[0052] [Characteristics (B)] Characteristic (B) is a characteristic in which the 80% spectral width at the maximum fluorescence intensity peak of the first wavelength-converted light 7 is 20 nm or more and less than 80 nm. Here, the 80% spectral width at the maximum fluorescence intensity peak refers to the spectral width at 80% of the emission peak intensity (maximum fluorescence intensity) at the maximum fluorescence intensity peak having the maximum fluorescence intensity among the peaks in the fluorescence spectrum of the first wavelength-converted light 7. The 80% spectral width is preferably 25 nm or more and less than 70 nm, more preferably 30 nm or more and less than 65 nm.

[0053] If the 80% spectral width is within the above range, fluorescent agents or photosensitizers can be used in fluorescence imaging or photodynamic therapy (PDT) without being affected by variations in the wavelength-dependent sensitivity of the agents. Here, photosensitizers refer to photosensitive agents. A light-emitting device that satisfies characteristic (B) can emit high-power near-infrared light that allows the agents to function properly, even if there are variations in the wavelength-dependent sensitivity of fluorescent agents or photosensitizers.

[0054] [Characteristics (C)] Characteristic (C) is a characteristic in which the ratio of the fluorescence intensity at a wavelength of 780 nm to the maximum fluorescence intensity in the fluorescence spectrum of the first wavelength-converted light 7 exceeds 30%. Hereinafter, this fluorescence intensity ratio will also be referred to as the "780 nm fluorescence intensity ratio." The 780 nm fluorescence intensity ratio is preferably greater than 60%, and more preferably greater than 80%.

[0055] When the 780 nm fluorescence intensity ratio is within the above range, the first wavelength-converted light 7 contains a large amount of fluorescent components in the near-infrared wavelength region (650 to 1000 nm) that is called the "biological window" and through which light easily penetrates a living body. Therefore, a light-emitting device that satisfies characteristic (C) can increase the intensity of near-infrared light that penetrates a living body.

[0056] [Characteristics (D)] The characteristic (D) is that the 1 / 10 decay of the first wavelength-converted light 7 is less than 1 ms. Here, the 1 / 10 decay is the time τ required for the intensity of the first wavelength-converted light 7 to decrease from the maximum emission intensity to 1 / 10 of the maximum emission intensity. 1 / 10 The 1 / 10 afterglow is preferably 10 μs or more and less than 1 ms, more preferably 10 μs or more and less than 800 μs, even more preferably 10 μs or more and less than 400 μs, particularly preferably 10 μs or more and less than 350 μs, and even more particularly preferably 10 μs or more and less than 100 μs.

[0057] When the 1 / 10 afterglow is within the above range, the output of the fluorescence emitted by the first phosphor 4 is less likely to saturate, even when the light density of the excitation light that excites the first phosphor 4 is high. Therefore, a light-emitting device that satisfies the characteristic (D) is less likely to saturate the output of the fluorescence when irradiated with a laser beam of high light density, and is able to emit high-output near-infrared light.

[0058] The 1 / 10 afterglow of the first wavelength-converted light 7 is Ce 3+ and Eu 2+ This is because the first wavelength-converted light 7 has a relatively long decay time, which is 1 / 10 of that of the fluorescence with a short decay time (less than 10 μs) based on the parity-allowed transition of Cr. 3+ This is because the fluorescence is based on spin-allowed electron energy transitions.

[0059] The first phosphor 4 is, for example, Lu2CaMg2(SiO4)3:Cr 3+ , Y3Ga2(AlO4)3:Cr 3+ , Y3Ga2(GaO4)3:Cr 3+ , Gd3Ga2(AlO4)3:Cr 3+ , Gd3Ga2(GaO4)3:Cr 3+ , (Y,La)3Ga2(GaO4)3:Cr 3+ , (Gd,La)3Ga2(GaO4)3:Cr 3+ , Ca2LuZr2(AlO4)3:Cr 3+ , Ca2GdZr2(AlO4)3:Cr 3+ , Lu3Sc2(GaO4)3:Cr 3+ , Y3Sc2(AlO4)3:Cr 3+ , Y3Sc2(GaO4)3:Cr 3+ , Gd3Sc2(GaO4)3:Cr 3+ , La3Sc2(GaO4)3:Cr 3+ , Ca3Sc2(SiO4)3:Cr 3+ , Ca3Sc2(GeO4)3:Cr 3+ , BeAl2O4:Cr 3+ , LiAl5O8:Cr 3+ , LiGa5O8:Cr 3+ , Mg2SiO4:Cr 3+ ,Li+ , La3Ga5GeO 14 :Cr 3+ , La3Ga 5.5 Nb 0.5 O 14 :Cr 3+ The following phosphors can be used.

[0060] The first phosphor 4 is preferably made of ceramics. When the first phosphor 4 is made of ceramics, the heat dissipation properties of the first phosphor 4 are improved, which suppresses a decrease in the output of the first phosphor 4 due to thermal quenching, enabling the light emitting device to emit high-output near-infrared light.

[0061] In the light emitting device 1, the first wavelength converted light 7 emitted from the first phosphor 4 is Cr 3+ The light emitting device 1 has a specific fluorescent component based on the electron energy transition of the above. As a result, the light emitting device 1 can efficiently excite fluorescent agents such as ICG and photosensitive agents (which are also fluorescent agents) such as phthalocyanine.

[0062] The first wavelength-converted light 7 preferably has light components over the entire wavelength range of 700 nm or more and less than 800 nm, and more preferably has light components over the entire wavelength range of 750 nm or more and less than 800 nm. This allows the fluorescent agent and photosensitizer to more efficiently absorb the near-infrared light components emitted by the first phosphor 4, thereby increasing the amount of near-infrared light emitted from the fluorescent agent and the amount of heat rays emitted from the photosensitizer. Therefore, when the first wavelength-converted light 7 has light components over the entire wavelength range of 700 nm or more and less than 800 nm, the amount of near-infrared light emitted from the fluorescent agent and the amount of heat rays emitted from the photosensitizer are increased, resulting in a light-emitting device suitable for medical use.

[0063] The fluorescence spectrum of the first wavelength-converted light 7 is 3+ Preferably, the spectrum contains no evidence of line components resulting from the electronic energy transition of Cr. 3+ The line component originating from the electron energy transition of Cr 3+If the fluorescence spectrum of the first wavelength-converted light 7 does not contain the above-mentioned trace, it is considered that the first wavelength-converted light 7 is a Cr 3+ Since it does not contain any long-lasting fluorescent components due to spin-forbidden transitions, a high-power point light source can be obtained with less saturation of the fluorescent output when irradiated with high-density laser light.

[0064] The wavelength converter 3 is made of Cr 3+ The first phosphor 4 contains only the first phosphor 4 which exhibits fluorescence based on the electron energy transition of Cr. 3+ Therefore, the light absorbed by the first phosphor 4 is 3+ Therefore, the first phosphor 4 is converted into fluorescence based on the electron energy transition of Cr. 3+ According to the light emitting device 1 that does not contain any other activators, it becomes easy to design output light that maximizes the output ratio of near-infrared fluorescent components.

[0065] The first phosphor 4 preferably has a garnet crystal structure. Garnet phosphors are easy to modify in composition, so many phosphor compounds can be produced. Therefore, when the first phosphor 4 has a garnet crystal structure, Cr 3+ It is easy to adjust the crystal field around Cr 3+ This makes it easy to control the color tone of the fluorescence based on the electron energy transition.

[0066] Phosphors with a garnet structure, particularly oxides, have a polyhedral particle shape close to a sphere, and exhibit excellent dispersibility of phosphor particle groups. Therefore, when the first phosphor 4 has a garnet structure, it is relatively easy to manufacture a wavelength converter 3 with excellent light transmittance, and the resulting light emitting device 1 can have high output. Furthermore, since phosphors with a garnet crystal structure have a proven track record as LED phosphors, a light emitting device 1 in which the first phosphor 4 has a garnet crystal structure will have high reliability.

[0067] The first phosphor 4 is preferably an oxide-based phosphor, and more preferably an oxide phosphor, which refers to a phosphor that contains oxygen but does not contain nitrogen.

[0068] Since oxides are stable in the atmosphere, when oxide phosphors generate heat due to high-density optical excitation by laser light, the phosphor crystals are less likely to be altered by oxidation in the atmosphere than nitride phosphors. If the first phosphor 4 is entirely made of an oxide-based phosphor, a highly reliable light-emitting device 1 can be obtained.

[0069] The first phosphor 4 is composed of two or more kinds of Cr 3+ The first phosphor 4 may contain two or more kinds of Cr activated phosphors. 3+ When the first phosphor 4 contains an activated phosphor, it is possible to control the output light component at least in the near-infrared wavelength region. 3+ A light emitting device including an activated phosphor makes it easy to adjust the spectral distribution of the near-infrared fluorescent component.

[0070] <Sealing material> In the wavelength converter 3, the first phosphor 4 is contained in the sealing material 5. Preferably, the first phosphor 4 is dispersed in the sealing material 5. When the first phosphor 4 is dispersed in the sealing material 5, it becomes possible to efficiently absorb the primary light 6 emitted by the light source 2 and efficiently convert the wavelength of the light into near-infrared light. Furthermore, when the first phosphor 4 is dispersed in the sealing material 5, it becomes easier to form the wavelength converter 3 into a sheet or film.

[0071] The sealing material 5 is made of at least one of an organic material and an inorganic material. The sealing material 5 is preferably made of at least one of a transparent (light-transmitting) organic material and a transparent (light-transmitting) inorganic material. Examples of organic sealing materials include transparent organic materials such as silicone resin. Examples of inorganic sealing materials include transparent inorganic materials such as low-melting-point glass.

[0072] The wavelength converter 3 is preferably made of an inorganic material. Here, inorganic material refers to materials other than organic materials, including ceramics and metals. By making the wavelength converter 3 out of an inorganic material, the thermal conductivity is higher than that of wavelength converters containing organic materials such as sealing resin, facilitating heat dissipation design. Therefore, even when the first phosphor 4 is photoexcited at high density by the primary light 6 emitted from the light source 2, the temperature rise of the wavelength converter 3 can be effectively suppressed. As a result, thermal quenching of the first phosphor 4 in the wavelength converter 3 is suppressed, enabling higher light output.

[0073] When the wavelength converter 3 is made of an inorganic material, the sealing material 5 is preferably made of an inorganic material. Furthermore, zinc oxide (ZnO) is preferable as the inorganic material for the sealing material 5. When the sealing material 5 is made of an inorganic material, the heat dissipation properties of the first phosphor 4 are further improved, thereby suppressing a decrease in the output of the first phosphor 4 due to thermal quenching, and enabling emission of high-output near-infrared light.

[0074] As a modification of the light emitting device 1, the wavelength converter 3 may be replaced with a wavelength converter that does not include a sealing material 5. In this case, an organic or inorganic binder may be used to bond the first phosphors 4 together. Alternatively, the first phosphors 4 may be bonded together by a thermal reaction of the first phosphors 4. As the binder, a commonly used resin-based adhesive, ceramic fine particles, low-melting-point glass, or the like may be used. A wavelength converter that does not include a sealing material 5 can reduce the thickness of the wavelength converter.

[0075] (action) The operation of the light emitting device 1 will be described. First, primary light 6 (laser light) emitted from the light source 2 is irradiated onto the front surface 3a of the wavelength converter 3. The irradiated primary light 6 passes through the wavelength converter 3. Then, as the primary light 6 passes through the wavelength converter 3, the first phosphor 4 contained in the wavelength converter 3 absorbs part of the primary light 6 and emits first wavelength-converted light 7. In this way, light containing the primary light 6 and the first wavelength-converted light 7 is emitted from the back surface 3b of the wavelength converter 3 as output light.

[0076] The light emitting device 1 is Cr 3+ Since the first wavelength-converted light 7 emits first wavelength-converted light having specific fluorescent components, including a large amount of near-infrared fluorescent components based on the electron energy transition of the above, the light source is suitable as a near-infrared light source for medical use or a near-infrared light source for sensing.

[0077] The light emitting device 1 can be a lighting device for a medical light source or a medical lighting device. The light emitting device 1 can also be a lighting device for a medical system that uses a fluorescence imaging method or photodynamic therapy. Since these medical systems use fluorescent agents, the light emitting device 1 for the medical system can also be said to be a light emitting device for a medical system that uses fluorescent agents.

[0078] The light-emitting device 1 as a medical light source or a lighting device for a medical lighting device is a light source or lighting device that illuminates the inside of a living body with broad, high-power near-infrared light through the "biological window," allowing fluorescent drugs and photosensitive drugs taken into the living body to function satisfactorily. Therefore, the light-emitting device 1 as a medical light source or a lighting device for a medical lighting device, particularly as a lighting device for a medical system using fluorescence imaging or photodynamic therapy, can be expected to have a significant therapeutic effect.

[0079] The light emitting device 1 can also be used as a light source for a sensing system or an illumination system for a sensing system. With the light emitting device 1, a highly sensitive sensing system can be configured using an orthodox light receiving element that has light receiving sensitivity in the near-infrared wavelength region. Therefore, by using the light emitting device 1 as a light source for a sensing system or an illumination system for a sensing system, a light emitting device can be obtained that facilitates miniaturization of the sensing system and widening of the sensing range.

[0080] [Second embodiment] A light emitting device 1A according to the second embodiment will be described. The light emitting device 1A according to the second embodiment uses a wavelength converter 3A instead of the wavelength converter 3 of the light emitting device 1 according to the first embodiment. The only difference between the light emitting device 1A according to the second embodiment and the light emitting device 1 according to the first embodiment is the wavelength converter 3A. Therefore, the following description will focus on the wavelength converter 3A, and descriptions of the configurations and functions of the other components will be omitted or simplified.

[0081] (wavelength converter) The wavelength converter 3A includes a first phosphor 4, a second phosphor 8, and a sealing material 5. In the wavelength converter 3A, the first phosphor 4 and the second phosphor 8 are contained in the sealing material 5. That is, the wavelength converter 3A of the light emitting device 1A further includes a second phosphor 8 that absorbs the primary light 6 and converts it into second wavelength-converted light 9 that has a longer wavelength than the primary light 6 and is different from the first wavelength-converted light 7.

[0082] The wavelength converter 3A is the same as the wavelength converter 3 of the light emitting device 1 according to the first embodiment, except that it further includes a second phosphor 8. Therefore, the following description will mainly focus on the second phosphor 8, and descriptions of other configurations and functions will be omitted or simplified.

[0083] <Second phosphor> The second phosphor 8 is a phosphor that absorbs the primary light 6 and converts it into second wavelength-converted light 9 that has a longer wavelength than the primary light 6 and is different from the first wavelength-converted light 7. In the light emitting device 1A, the wavelength converter 3A further comprises the second phosphor 8 in addition to the first phosphor 4, and therefore the light emitting device 1A is able to emit white output light by additive color mixing with the primary light 6 emitted by the light source 2, for example, blue laser light.

[0084] In this way, when the wavelength converter 3A further comprises the second phosphor 8 in addition to the first phosphor 4, it becomes possible to control the shape and excitation characteristics of the fluorescence spectrum emitted from the wavelength converter 3A, and therefore the spectral distribution of the output light of the obtained light emitting device 1A can be easily adjusted depending on the intended use.

[0085] The second phosphor 8 contained in the wavelength converter 3A is not particularly limited as long as it can absorb the primary light 6 emitted by the light source 2 and emit the second wavelength-converted light 9, which is visible light. The second phosphor 8 is preferably a garnet type, a calcium ferrite type, or a lanthanum silicon nitride (La3Si6N 11 ) type crystal structure. 3+ The second phosphor 8 is preferably a garnet type, a calcium ferrite type, or a lanthanum silicon nitride (La3Si6N 11 ) type crystal structure. 3+ The use of such second phosphor 8 makes it possible to obtain output light containing a large amount of green to yellow light components.

[0086] Examples of the second phosphor 8 include M3RE2(SiO4)3, RE3Al2(AlO4)3, MRE2O4, and RE3Si6N 11 A Ce based on a compound (B) having as its main component at least one selected from the group consisting of 3+ The second phosphor 8 is, for example, M3RE2(SiO4)3, RE3Al2(AlO4)3, MRE2O4, and RE3Si6N. 11 Ce having at least one base selected from the group consisting of 3+ The second phosphor 8 is preferably a Ce phosphor having a solid solution matrix containing the compound (B) as an end member. 3+ In the compound (B), M is an alkaline earth metal, and RE is a rare earth element.

[0087] These second phosphors 8 effectively absorb light in the wavelength range of 430 nm to 480 nm and convert it with high efficiency into green to yellow light having a maximum intensity in the wavelength range of 540 nm to 590 nm. Therefore, by using the light source 2 that emits cool color light as the primary light 6 as the second phosphor 8, it becomes possible to easily obtain visible light components.

[0088] When the wavelength converter 3A includes a first phosphor 4 and a second phosphor 8, the first phosphor 4 preferably emits first wavelength-converted light 7 by absorbing at least one of the primary light 6 emitted by the light source 2 and the second wavelength-converted light 9 emitted by the second phosphor 8. As described above, the first phosphor 4 is preferably a phosphor that absorbs the primary light 6 emitted by the light source 2 and emits the first wavelength-converted light 7, which is near-infrared light.

[0089] The first phosphor 4 may be a phosphor that absorbs the second wavelength-converted light 9 emitted by the second phosphor 8 and emits the first wavelength-converted light 7, which is near-infrared light. That is, the second phosphor 8 may be excited by the primary light 6 to emit the second wavelength-converted light 9, and the first phosphor 4 may be excited by the second wavelength-converted light 9 to emit the first wavelength-converted light 7. In this case, even if the first phosphor 4 is a phosphor that is hardly excited by the primary light 6, it can be excited by the fluorescence emitted by the second phosphor 8 via the second phosphor 8.

[0090] Therefore, when the first phosphor 4 absorbs the second wavelength-converted light 9 and emits the first wavelength-converted light 7, a phosphor that absorbs visible light can be selected as the first phosphor 4, thereby expanding the options for the first phosphor 4 and facilitating industrial production of the light emitting device 1A. Furthermore, when the first phosphor 4 absorbs the second wavelength-converted light 9 and emits the first wavelength-converted light 7, the light emitting device 1A can emit the first wavelength-converted light 7 with a high intensity of the near-infrared light component.

[0091] The second phosphor 8 is composed of two or more kinds of Cr 3+ The second phosphor 8 may contain two or more kinds of Cr.3+ When an activated phosphor is included, the output light component in at least the near-infrared wavelength region can be controlled, making it easy to adjust the spectral distribution of the near-infrared fluorescent component.

[0092] (action) The operation of the light emitting device 1A will be described. First, primary light 6 (laser light) emitted from the light source 2 is irradiated onto the front surface 3a of the wavelength converter 3A. The irradiated primary light 6 passes through the wavelength converter 3A. Then, as the primary light 6 passes through the wavelength converter 3A, the second phosphor 8 contained in the wavelength converter 3A absorbs a portion of the primary light 6 and emits second wavelength-converted light 9. Furthermore, the first phosphor 4 contained in the wavelength converter 3A absorbs a portion of the primary light 6 and / or second wavelength-converted light 9 and emits first wavelength-converted light 7. In this way, light containing the primary light 6, the first wavelength-converted light 7, and the second wavelength-converted light 9 is emitted as output light from the back surface 3b of the wavelength converter 3A.

[0093] The light emitting device 1A is 3+ Since the first wavelength-converted light 7 emits first wavelength-converted light having specific fluorescent components, including a large amount of near-infrared fluorescent components based on the electron energy transition of the above, the light source is suitable as a near-infrared light source for medical use or a near-infrared light source for sensing.

[0094] The light emitting device 1A can be used as a medical light source or a lighting device for a medical lighting device. Furthermore, the light emitting device 1A can be used as a lighting device for a medical system using a fluorescence imaging method or photodynamic therapy. Since these medical systems use fluorescent drugs or photosensitive drugs, the light emitting device 1A for the medical system can also be said to be a light emitting device for a medical system using fluorescent drugs or photosensitive drugs.

[0095] The light emitting device 1A serves as a light source or lighting device that can illuminate the inside of a living body with broad, high-power near-infrared light through the "biological window," thereby enabling fluorescent drugs and photosensitizers taken into the living body to function fully. Therefore, the light emitting device 1A can be expected to have a significant therapeutic effect.

[0096] The light emitting device 1A can also be used as a light source for a sensing system or an illumination system for a sensing system. The light emitting device 1A can be used to configure a highly sensitive sensing system using a conventional light-receiving element that has sensitivity in the near-infrared wavelength region. Therefore, the light emitting device 1A can provide a light emitting device that facilitates miniaturization of the sensing system and widening of the sensing range.

[0097] [Third embodiment] A light emitting device 1B according to the third embodiment will be described. The light emitting device 1B according to the third embodiment uses a wavelength converter 3B instead of the wavelength converter 3 of the light emitting device 1 according to the first embodiment. The only difference between the light emitting device 1B according to the third embodiment and the light emitting device 1 according to the first embodiment is the wavelength converter 3B. Therefore, the following description will focus on the wavelength converter 3B, and descriptions of the structures and functions of the other components will be omitted or simplified.

[0098] (wavelength converter) The wavelength converter 3B includes a first phosphor 4 and a sealing material 5. In the wavelength converter 3B, the first phosphor 4 is contained in the sealing material 5. The wavelength converter 3B is the same as the wavelength converter 3 of the light emitting device 1 according to the first embodiment in that it includes the first phosphor 4 and the sealing material 5, but its optical action is different from that of the wavelength converter 3.

[0099] In the wavelength converter 3 of the light emitting device 1 according to the first embodiment, the primary light 6 irradiated onto the wavelength converter 3 is transmitted through the wavelength converter 3. On the other hand, in the wavelength converter 3B, most of the primary light 6 irradiated onto the wavelength converter 3B enters the wavelength converter 3B from the front surface 3a of the wavelength converter 3B, and the remainder is reflected by the front surface 3a.

[0100] The wavelength converter 3B is configured so that the irradiated light of the primary light 6 (laser light) enters the front surface 3a of the wavelength converter 3B, and the output light of the first phosphor 4 is emitted from the front surface 3a of the wavelength converter 3B. As a result, most of the primary light 6 irradiated onto the wavelength converter 3B enters the wavelength converter 3B from the front surface 3a of the wavelength converter 3B, and the remainder is reflected by the front surface 3a.

[0101] (action) The operation of the light emitting device 1B will be described. First, primary light 6 (laser light) emitted from the light source 2 is irradiated onto the front surface 3a of the wavelength converter 3B. Most of the primary light 6 enters the wavelength converter 3B from the front surface 3a of the wavelength converter 3B, and the remainder is reflected by the front surface 3a. In the wavelength converter 3B, first wavelength-converted light 7 is emitted from the first phosphor 4 excited by the primary light 6, and the first wavelength-converted light 7 is emitted from the front surface 3a.

[0102] The light emitting device 1B is Cr 3+ Since the first wavelength-converted light 7 emits first wavelength-converted light having specific fluorescent components, including a large amount of near-infrared fluorescent components based on the electron energy transition of the above, the light source is suitable as a near-infrared light source for medical use or a near-infrared light source for sensing.

[0103] The light emitting device 1B can be a lighting device for a medical light source or a medical lighting device. Furthermore, the light emitting device 1B can be a lighting device for a medical system that uses a fluorescence imaging method or photodynamic therapy. Since these medical systems use fluorescent drugs or photosensitive drugs, the light emitting device 1B for the medical system can also be said to be a light emitting device for a medical system that uses fluorescent drugs or photosensitive drugs.

[0104] Light-emitting device 1B serves as a light source or lighting device that can illuminate the inside of a living body with broad, high-power near-infrared light through the "biological window," thereby enabling fluorescent drugs and photosensitizers taken into the living body to function fully. Therefore, light-emitting device 1B can be obtained that can be expected to have a significant therapeutic effect.

[0105] The light emitting device 1B can also be used as a light source for a sensing system or an illumination system for a sensing system. The light emitting device 1B can be used to configure a highly sensitive sensing system using a conventional light-receiving element that has sensitivity in the near-infrared wavelength region. Therefore, the light emitting device 1B can provide a light emitting device that facilitates miniaturization of the sensing system and widening of the sensing range.

[0106] [Fourth embodiment] A light emitting device 1C according to the fourth embodiment will be described. The light emitting device 1C according to the fourth embodiment uses a wavelength converter 3C instead of the wavelength converter 3A of the light emitting device 1A according to the second embodiment. The only difference between the light emitting device 1C according to the fourth embodiment and the light emitting device 1A according to the second embodiment is the wavelength converter 3C. Therefore, the following description will focus on the wavelength converter 3C, and descriptions of the configurations and functions of the other components will be omitted or simplified.

[0107] (wavelength converter) The wavelength converter 3C includes a first phosphor 4, a second phosphor 8, and a sealing material 5. In the wavelength converter 3C, the first phosphor 4 and the second phosphor 8 are contained in the sealing material 5. That is, the wavelength converter 3C of the light emitting device 1C further includes a second phosphor 8 that absorbs the primary light 6 and converts it into second wavelength-converted light 9 that has a longer wavelength than the primary light 6 and is different from the first wavelength-converted light 7. The wavelength converter 3C is the same as the wavelength converter 3A of the light emitting device 1A according to the second embodiment in that it includes the first phosphor 4, the second phosphor 8, and a sealing material 5, but its optical action differs from that of the wavelength converter 3A.

[0108] The second phosphor 8 used in the wavelength converter 3C is the same as that used in the wavelength converter 3A of the light emitting device 1A according to the second embodiment, and therefore a description thereof will be omitted. The inclusion of the second phosphor 8 in the wavelength converter 3C enables the light emitting device 1C to emit white output light through additive color mixing with the primary light 6 emitted by the light source 2, for example, blue laser light.

[0109] In this way, by using an appropriate combination of the first phosphor 4 and the second phosphor 8, it becomes possible to control the shape of the fluorescence spectrum and the excitation characteristics of the first wavelength-converted light 7. Therefore, the spectral distribution of the output light of the obtained light-emitting device C can be easily adjusted depending on the intended use.

[0110] In the wavelength converter 3A of the light emitting device 1 according to the second embodiment, the primary light 6 irradiated onto the wavelength converter 3A is transmitted through the wavelength converter 3. On the other hand, in the wavelength converter 3C, most of the primary light 6 irradiated onto the wavelength converter 3C enters the wavelength converter 3C from the front surface 3a of the wavelength converter 3C, and the remainder is reflected by the front surface 3a.

[0111] The wavelength converter 3C is configured so that the irradiated light of the primary light 6 (laser light) is incident on the front surface 3a of the wavelength converter 3B, and the output light of the first phosphor 4 is emitted from the front surface 3a of the wavelength converter 3B. As a result, most of the primary light 6 irradiated onto the wavelength converter 3C enters the wavelength converter 3C from the front surface 3a of the wavelength converter 3C, and the remainder is reflected by the front surface 3a.

[0112] (action) In the light emitting device 1C shown in Fig. 4, first, primary light 6 (laser light) emitted from the light source 2 is irradiated onto the front surface 3a of the wavelength converter 3C. Most of the primary light 6 enters the wavelength converter 3C from the front surface 3a of the wavelength converter 3C, and the remainder is reflected by the front surface 3a. In the wavelength converter 3C, second wavelength-converted light 9 is emitted from the second phosphor 8 excited by the primary light 6, and first wavelength-converted light 7 is emitted from the first phosphor 4 excited by the primary light 6 and / or the second wavelength-converted light 9. Then, the first wavelength-converted light 7 and the second wavelength-converted light 9 are emitted from the front surface 3a.

[0113] The light emitting device 1C is Cr 3+ Since the first wavelength-converted light 7 emits first wavelength-converted light having specific fluorescent components, including a large amount of near-infrared fluorescent components based on the electron energy transition of the above, the light source is suitable as a near-infrared light source for medical use or a near-infrared light source for sensing.

[0114] The light emitting device 1C can be a lighting device for a medical light source or a medical lighting device. Furthermore, the light emitting device 1C can be a lighting device for a medical system that uses a fluorescence imaging method or photodynamic therapy. Since these medical systems use fluorescent drugs or photosensitive drugs, the light emitting device 1C for the medical system can also be said to be a light emitting device for a medical system that uses fluorescent drugs or photosensitive drugs.

[0115] Light-emitting device 1C serves as a light source or lighting device that can illuminate the inside of a living body with broad, high-power near-infrared light through the "biological window," thereby enabling fluorescent drugs and photosensitizers taken into the living body to function fully. Therefore, light-emitting device 1C can be obtained as a light-emitting device that can be expected to have a significant therapeutic effect.

[0116] The light emitting device 1C can also be used as a light source for a sensing system or an illumination system for a sensing system. The light emitting device 1C can be used to configure a highly sensitive sensing system using a conventional light-receiving element that has sensitivity in the near-infrared wavelength region. Therefore, the light emitting device 1C can provide a light emitting device that facilitates miniaturization of the sensing system and widening of the sensing range.

[0117] [Electronic equipment] An electronic device according to this embodiment can be obtained by using any of the light emitting devices 1 to 1C described above. That is, the electronic device according to this embodiment includes any of the light emitting devices 1 to 1C according to this embodiment. The light emitting devices 1 to 1C are expected to have a significant therapeutic effect and facilitate miniaturization of the sensing system. Since the electronic device according to this embodiment uses the light emitting device according to this embodiment, when used for medical equipment or sensing equipment, a significant therapeutic effect and a miniaturization of the sensing system can be expected.

[0118] [Endoscopes and endoscope systems] The endoscope according to this embodiment is equipped with the above-described medical light-emitting device. An example of an endoscope according to this embodiment and an endoscopic system using the endoscope will be described below with reference to Figures 6 and 7. The endoscope described below is an example equipped with a light-emitting device 1A or 1C that emits visible light in addition to near-infrared light.

[0119] (Endoscopy) As shown in FIG. 6, the endoscope 11 includes a scope 110, a light source connector 111, a mount adapter 112, a relay lens 113, a camera head 114, and an operation switch 115.

[0120] The scope 110 is a long, thin light-guiding member capable of guiding light from the distal end to the distal end, and is inserted into the body during use. The scope 110 has an imaging window 110z at its distal end, which is made of an optical material such as optical glass or optical plastic. The scope 110 further has an optical fiber that guides light introduced from the light source connector 111 to the distal end, and an optical fiber through which the optical image incident from the imaging window 110z is transmitted.

[0121] The mount adapter 112 is a member for attaching the scope 110 to the camera head 114. Various types of scopes 110 can be detachably attached to the mount adapter 112.

[0122] The light source connector 111 introduces illumination light from the light emitting device 1A or 1C to be irradiated onto an affected area or the like inside the body. In this embodiment, the illumination light includes visible light and near-infrared light. The light introduced into the light source connector 111 is guided to the tip of the scope 110 via an optical fiber and is irradiated onto an affected area or the like inside the body through an imaging window 110z. As shown in FIG. 6, a transmission cable 111z is connected to the light source connector 111 to guide the illumination light from the light emitting device 1A or 1C to the scope 110. The transmission cable 111z may include an optical fiber.

[0123] The relay lens 113 converges the optical image transmitted through the scope 110 onto the imaging surface of the image sensor. Note that the relay lens 113 may perform focus adjustment and magnification adjustment by moving the lens in accordance with the amount of operation of the operation switch 115.

[0124] Camera head 114 has a color separation prism inside. The color separation prism separates the light converged by relay lens 113 into four colors: R light (red light), G light (green light), B light (blue light), and IR light (near-infrared light). The color separation prism is made of a light-transmitting material such as glass.

[0125] The camera head 114 further includes an internal image sensor as a detector. For example, four image sensors are provided, and each of the four image sensors converts an optical image formed on its imaging surface into an electrical signal. The image sensor is not particularly limited, but at least one of a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) can be used. The four image sensors are dedicated sensors that receive light of the IR component (near-infrared component), B component (blue component), R component (red component), and G component (green component), respectively.

[0126] Camera head 114 may have a color filter inside instead of a color separation prism. The color filter is provided on the imaging surface of the image sensor. For example, four color filters are provided, and the four color filters receive light converged by relay lens 113 and selectively transmit R light (red light), G light (green light), B light (blue light), and IR light (near-infrared light), respectively.

[0127] It is preferable that the color filter that selectively transmits IR light is equipped with a barrier film that blocks the reflected components of near-infrared light (IR light) contained in the illumination light. This allows only the fluorescence of IR light emitted from ICG to be imaged on the imaging surface of the IR light image sensor. This makes it easier to clearly observe the affected area illuminated by ICG.

[0128] As shown in FIG. 6, a signal cable 114z is connected to the camera head 114 for transmitting an electric signal from the image sensor to the CCU 12, which will be described later.

[0129] In the endoscope 11 configured as above, light from the subject passes through the scope 110 and is guided to the relay lens 113, and then passes through a color separation prism in the camera head 114 to form an image on four image sensors.

[0130] (Endoscopy system) As shown in FIG. 7, the endoscope system 100 includes an endoscope 11 that captures images of the inside of a subject, a CCU (Camera Control Unit) 12, a light emitting device 1A or 1C, and a display device 13 such as a display.

[0131] The CCU 12 includes at least an RGB signal processing section, an IR signal processing section, and an output section. The CCU 12 executes programs stored in an internal or external memory of the CCU 12 to realize the functions of the RGB signal processing section, the IR signal processing section, and the output section.

[0132] The RGB signal processing unit converts the B, R, and G component electrical signals from the image sensor into a video signal that can be displayed on the display device 13 and outputs it to the output unit. The IR signal processing unit converts the IR component electrical signal from the image sensor into a video signal and outputs it to the output unit.

[0133] The output unit outputs at least one of the video signal of each RGB color component and the video signal of the IR component to the display device 13. For example, the output unit outputs the video signal based on either a simultaneous output mode or a superimposed output mode.

[0134] In the simultaneous output mode, the output unit simultaneously outputs an RGB image and an IR image on separate screens. The simultaneous output mode allows the RGB image and the IR image to be compared on separate screens to observe the affected area. In the superimposed output mode, the output unit outputs a composite image in which the RGB image and the IR image are superimposed. The superimposed output mode allows, for example, the affected area illuminated by ICG to be clearly observed within the RGB image.

[0135] The display device 13 displays an image of an object such as an affected area on the screen based on a video signal from the CCU 12. In the simultaneous output mode, the display device 13 divides the screen into multiple sections and displays an RGB image and an IR image side by side on each section. In the superimposed output mode, the display device 13 displays a composite image in which the RGB image and the IR image are superimposed on one screen.

[0136] (action) Next, we will explain the operations of the endoscope 11 and the endoscope system 100 according to this embodiment. When observing a subject using the endoscope system 100, first, indocyanine green (ICG), a fluorescent substance, is administered to the subject. This causes the ICG to accumulate in lymph nodes, tumors, and other areas (affected areas).

[0137] Next, visible light and near-infrared light are introduced from the light-emitting device 1A or 1C to the light source connector 111 via a transmission cable 111z. The light introduced into the light source connector 111 is guided to the tip side of the scope 110 and projected from the imaging window 110z, thereby irradiating the area including the affected area and its surroundings. Light reflected from the affected area and the fluorescence emitted from the ICG are guided to the rear end side of the scope 110 via the imaging window 110z and optical fiber, converged by a relay lens 113, and incident on a color separation prism inside the camera head 114.

[0138] In the color separation prism, of the incident light, the IR component light separated by the IR separation prism is captured as an optical image of the infrared light component by the IR image sensor. The B component light separated by the blue separation prism is captured as an optical image of the blue component by the blue image sensor. The R component light separated by the red separation prism is captured as an optical image of the red component by the red image sensor. The G component light separated by the green separation prism is captured as an optical image of the green component by the green image sensor.

[0139] The IR component electrical signal converted by the IR image sensor is converted into a video signal by an IR signal processing unit inside the CCU 12. The B component, R component, and G component electrical signals converted by the RGB image sensors are converted into respective video signals by an RGB signal processing unit inside the CCU 12. The IR component video signal and the B component, R component, and G component video signals are output to the display device 13 in synchronization.

[0140] When the simultaneous output mode is set in the CCU 12, the RGB image and the IR image are simultaneously displayed on two screens on the display device 13. When the superimposed output mode is set in the CCU 12, the display device 13 displays a composite image in which the RGB image and the IR image are superimposed.

[0141] As described above, the endoscope 11 according to this embodiment includes the medical light emitting devices 1, 1A, 1B, and 1C. Therefore, by using the endoscope 11 to efficiently excite the fluorescent agent to emit light, it becomes possible to clearly observe the affected area.

[0142] The endoscope 11 according to this embodiment preferably further includes a detector that detects fluorescence emitted from the fluorescent agent that has absorbed the first wavelength-converted light 7. By integrating the light emitting devices 1, 1A, 1B, and 1C with a detector that detects fluorescence emitted from the fluorescent agent, the affected area can be identified using the endoscope alone. This eliminates the need to perform a large abdominal incision to identify the affected area as in the past, making it possible to perform examinations and treatments that place less strain on the patient. Furthermore, because the doctor using the endoscope 11 can accurately identify the affected area, it is possible to improve the efficiency of treatment.

[0143] [How to use the light emitting device] Next, a method of using the light-emitting device according to this embodiment will be described. The method of using the light-emitting device according to this embodiment is a method of using the light-emitting device when the light-emitting device is an illumination device for a medical system using a fluorescence imaging method or photodynamic therapy. The method of using the light-emitting device according to this embodiment includes the steps of administering a fluorescent drug or a photosensitizer to a subject, and irradiating the subject with which the fluorescent drug or the photosensitizer has come into contact with first wavelength-converted light. Below, the method of using the light-emitting device according to this embodiment will be described in detail, divided into a method of using the light-emitting device using a fluorescence imaging method and a method of using the light-emitting device using photodynamic therapy.

[0144] (Method of using a light-emitting device using a fluorescence imaging method) First, a method of using a light-emitting device that uses a fluorescence imaging method will be described. The method of using a light-emitting device that uses a fluorescence imaging method is a method of using the light-emitting devices 1, 1A, 1B, and 1C described above as examples of medical light-emitting devices as lighting devices for medical systems or when using an endoscope 11, and uses the fluorescence imaging method. The method of using a light-emitting device that uses a fluorescence imaging method includes the steps of administering a fluorescent agent to a subject and irradiating the subject that has come into contact with the fluorescent agent with first wavelength-converted light 7.

[0145] In a method for using a light-emitting device using a fluorescence imaging method, a fluorescent agent is first administered to a subject to specifically accumulate in an affected area within the subject. As described above, the fluorescent agent administered to the subject can be an agent that absorbs excitation light in the near-infrared region and emits fluorescence in the near-infrared region at a wavelength longer than that of the excitation light. For example, the fluorescent agent can be at least one selected from the group consisting of indocyanine green (ICG), phthalocyanine-based compounds, talaporfin sodium-based compounds, and dipicolylcyanine (DIPCY)-based compounds.

[0146] Next, the subject with which the fluorescent agent has come into contact is irradiated with first wavelength-converted light 7. As described above, the first wavelength-converted light 7 is emitted from the medical light emitting device 1, 1A, 1B, 1C or the endoscope 11, and contains light components over the entire wavelength range of at least 700 nm to 800 nm. Since light in the near-infrared region is not easily scattered by hemoglobin and water in a living body and easily penetrates the living body, the first wavelength-converted light 7 penetrates the living body and excites the fluorescent agent. The excited fluorescent agent has a longer wavelength than the excitation light and emits fluorescence in the near-infrared region. The fluorescence emitted from the fluorescent agent in this way is detected using a detector, making it possible to observe and treat the affected area in the living body.

[0147] As described above, the first wavelength-converted light 7 has light components over at least the entire wavelength range of 700 nm to 800 nm, and therefore can excite the fluorescent agent with high efficiency even if the fluorescent agent has variations in characteristics. Furthermore, when the solid-state light-emitting element 2 of the medical light-emitting device 1, 1A, 1B, or 1C emits laser light, the first wavelength-converted light 7 emitted from the first phosphor 4 has high intensity. This makes it possible to excite the fluorescent agent in the subject with high efficiency and emit fluorescence with a long wavelength.

[0148] (Method of using a light-emitting device for photodynamic therapy) Next, a method of using the light-emitting device for photodynamic therapy will be described. The method of using the light-emitting device for photodynamic therapy is a method of using the light-emitting devices 1, 1A, 1B, and 1C described above as examples of medical light-emitting devices as lighting devices for medical systems or using an endoscope 11, and involves photodynamic therapy. The method of using the light-emitting device for photodynamic therapy includes the steps of administering a photosensitizer and irradiating a subject with which the photosensitizer has come into contact with first wavelength-converted light 7. Here, the photosensitizer refers to a substance that absorbs light and generates heat and reactive oxygen species. The photosensitizer is also referred to as a photosensitizer, photosensitive compound, photosensitizer, pyrogen, etc.

[0149] In a method for using a light-emitting device for photodynamic therapy, a photosensitizer is first administered to a subject, and the photosensitizer is allowed to specifically accumulate at an affected area within the subject. As described above, the photosensitizer administered to the subject can be a drug that absorbs excitation light in the near-infrared light region and generates heat or reactive oxygen species. For example, the photosensitizer can be at least one selected from the group consisting of phthalocyanine-based compounds, talaporfin sodium-based compounds, and porfilmer sodium-based compounds.

[0150] Next, the subject in contact with the photosensitizer is irradiated with first wavelength-converted light 7. As described above, the first wavelength-converted light 7 is emitted from the medical light emitting device 1, 1A, 1B, 1C or the endoscope 11 and contains light components over the entire wavelength range of at least 700 nm to 800 nm. Light in the near-infrared region is not easily scattered by hemoglobin and water in the living body and easily penetrates the living body, so the first wavelength-converted light 7 penetrates the living body and irradiates the photosensitizer. The photosensitizer irradiated with the first wavelength-converted light 7 generates heat and reactive oxygen species. The heat and reactive oxygen species generated by the photosensitizer kill cancer cells, making it possible to treat the affected area in the living body.

[0151] As described above, the first wavelength-converted light 7 has light components over at least the entire wavelength range of 700 nm to 800 nm, so that even if the photosensitizer has variations in its characteristics, it is possible to generate heat and reactive oxygen species from the photosensitizer with high efficiency. Furthermore, when the solid-state light-emitting element 2 of the medical light-emitting device 1, 1A, 1B, or 1C emits laser light, the first wavelength-converted light 7 emitted from the first phosphor 4 has high intensity. This makes it possible to generate heat and reactive oxygen species from the photosensitizer with high efficiency.

[0152] Fluorescent agents used in fluorescence imaging and photosensitizers used in photodynamic therapy can exhibit changes in absorption spectra within the subject due to factors such as solvatochromic effects, changes in electron-withdrawing properties due to association, and differences in the types of functional groups, substituents, and side chains. The solvatochromic effect refers to the change in ground and excited states caused by changes in solvent polarity. Association refers to the bonding of identical molecules due to intermolecular forces. Therefore, if the light emitted by a solid-state light-emitting device, such as a laser element, has a narrow half-width of the emission spectrum, it may not be able to accommodate changes in the absorption spectrum of the drug. Specifically, if the light emitted by a solid-state light-emitting device has a narrow half-width of the emission spectrum, the efficiency of the drug's light-to-heat energy conversion and the efficiency of the drug's light-to-thermal energy conversion may be reduced. [Example]

[0153] [Example 1] (Preparation of phosphor) The oxide phosphor was synthesized using a preparation method using a solid-state reaction. 0.98 ,Cr 0.02 An oxide phosphor represented by the formula )2(GaO4)3 was synthesized. The following compound powders were used as the main raw materials when synthesizing the oxide phosphor. Yttrium oxide (Y2O3): 3N purity, manufactured by Shin-Etsu Chemical Co., Ltd. Gallium oxide (Ga2O3): 4N purity, manufactured by Asia Materials Co., Ltd. Chromium oxide (Cr2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd.

[0154] First, the stoichiometric compound Y3(Ga 0.98 ,Cr 0.02 The raw materials were weighed so that the composition was )2(GaO4)3. Next, the raw materials were dry mixed using a mortar and pestle to prepare the firing raw material.

[0155] The raw materials for firing were transferred to an alumina crucible with a lid, and fired in a box-type electric furnace in the atmosphere at 1600°C for 2 hours. The fired product was then lightly crushed to obtain the phosphor of Example 1. Note that the sample after firing was Y3(Ga 0.98 ,Cr 0.02 The identity of the compound was confirmed by X-ray diffraction.

[0156] (Evaluation of emission spectrum) The emission spectrum of the phosphor was evaluated using a spectrofluorometer FP-6500 (manufactured by JASCO Corporation).

[0157] [Example 2] (Preparation of phosphor) The oxide phosphor was synthesized using a preparation method using a solid-state reaction. 0.98 ,Cr 0.02 An oxide phosphor represented by the formula )2(GaO4)3 was synthesized. The following compound powders were used as the main raw materials when synthesizing the oxide phosphor. Gadolinium oxide (Gd2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd. Gallium oxide (Ga2O3): 4N purity, manufactured by Asia Materials Co., Ltd. Chromium oxide (Cr2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd.

[0158] First, the stoichiometric compound Gd3(Ga 0.98 ,Cr 0.02 The raw materials were weighed so that the composition was )2(GaO4)3. Next, the raw materials were dry mixed using a mortar and pestle to prepare the firing raw material.

[0159] The raw material for firing was transferred to an alumina crucible with a lid and fired in a box-type electric furnace in the atmosphere at 1600°C for 2 hours. The fired product was then lightly crushed to obtain the phosphor of Example 2. Note that the sample after firing was Gd3(Ga 0.98 ,Cr 0.02 The identity of the compound was confirmed by X-ray diffraction.

[0160] (Evaluation of emission spectrum) The emission spectrum of the phosphor was evaluated in the same manner as in Example 1. The results are shown in FIG.

[0161] [Example 3] (Preparation of phosphor) The oxide phosphor was synthesized using a preparation method using solid-state reaction. 0.75 ,La 0.25 )3(Ga 0.98 ,Cr 0.02 An oxide phosphor represented by the formula )2(GaO4)3 was synthesized. The following compound powders were used as the main raw materials when synthesizing the oxide phosphor. Gadolinium oxide (Gd2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd. Lanthanum oxide (La2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd. Gallium oxide (Ga2O3): 4N purity, manufactured by Asia Materials Co., Ltd. Chromium oxide (Cr2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd.

[0162] First, a stoichiometric compound (Gd 0.75 ,La 0.25 )3(Ga 0.98 ,Cr 0.02 The raw materials were weighed so that the composition was )2(GaO4)3. Next, the raw materials were dry mixed using a mortar and pestle to prepare the firing raw material.

[0163] The raw material for firing was transferred to an alumina crucible with a lid and fired in a box-type electric furnace in the atmosphere at 1400°C for 2 hours. The fired product was then lightly crushed to obtain the phosphor of Example 3. Note that the sample after firing contained (Gd 0.75 ,La0.25 )3(Ga 0.98 ,Cr 0.02 The identity of the compound was confirmed by X-ray diffraction.

[0164] (Evaluation of emission spectrum) The emission spectrum of the phosphor was evaluated in the same manner as in Example 1. The results are shown in FIG.

[0165] [Comparative Example 1] (Preparation of phosphor) The oxide phosphor was synthesized using a preparation method using solid-state reaction. 0.98 ,Cr 0.02 An oxide phosphor represented by the composition formula: )2(AlO4)3 was synthesized. The following compound powders were used as the main raw materials when synthesizing the oxide phosphor. Yttrium oxide (Y2O3): 3N purity, manufactured by Shin-Etsu Chemical Co., Ltd. Aluminum oxide (Al2O3): 3N purity, manufactured by Sumitomo Chemical Co., Ltd. Chromium oxide (Cr2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd.

[0166] First, the stoichiometric compound Y3 (Al 0.98 ,Cr 0.02 The raw materials were weighed so that the composition was )2(AlO4)3. Next, the raw materials were dry mixed using a mortar and pestle to prepare the firing raw material.

[0167] The raw materials for firing were transferred to an alumina crucible with a lid, and fired in a box-type electric furnace in the atmosphere at 1600°C for 2 hours. The fired product was then lightly crushed to obtain a phosphor of Comparative Example 1. Note that the sample after firing was Y3 (Al 0.98 ,Cr 0.02 The identity of the compound was confirmed by X-ray diffraction.

[0168] (Evaluation of emission spectrum) The emission spectrum of the phosphor was evaluated in the same manner as in Example 1. The results are shown in FIG.

[0169] 8 shows the emission spectrum when excited with an excitation wavelength of 450 nm, along with the emission spectra of Example 2, Example 3, and Comparative Example 1. Table 1 shows the emission peak wavelength λ, which is the peak wavelength of the maximum fluorescence intensity peak in the emission spectrum. MAX Table 1 also shows the spectral width (80% spectral width) W at 80% of the emission peak intensity (maximum fluorescence intensity) of the maximum fluorescence intensity peak. 80% Furthermore, Table 1 shows the 780 nm fluorescence intensity ratio L, which is the ratio of the emission intensity at a wavelength of 780 nm to the emission peak intensity (maximum fluorescence intensity) at the maximum fluorescence intensity peak of the emission spectrum. 780nm Shows.

[0170] [Table 1]

[0171] (Summary of emission spectrum evaluation) It was found that the phosphors of Examples 1 to 3 emit wavelength-converted light that contains more broad spectral components with a maximum fluorescence intensity in the wavelength range beyond 710 nm than linear spectral components with a maximum fluorescence intensity in the wavelength range of 680 to 710 nm. The above linear spectrum component is Cr 3+ of, 2 T1 and 2 E → 4 A2(t2 3 ) is a long-lasting light component based on the electron energy transition (spin-forbidden transition). 4 T2 → 4 This is a short-lasting light component based on the electron energy transition (spin-allowed transition) of A2. Therefore, it was found that a point light source containing a large amount of near-infrared components can be easily produced by using the light emitting device using the phosphors of Examples 1 to 3 as the first phosphor.

[0172] Furthermore, it was found that, with the light-emitting devices using the phosphors of Examples 1 to 3 as the first phosphor, the fluorescent agents and photosensitizers can be used in fluorescence imaging and photodynamic therapy (PDT) without being affected by variations in the wavelength dependency of the sensitivity of the fluorescent agents and photosensitizers. In other words, even if there is variation in the wavelength dependency of the sensitivity of the fluorescent agents and photosensitizers, it was found that the agents can function sufficiently without being affected by this variation.

[0173] Furthermore, it was found that in the light emitting devices using the phosphors of Examples 1 to 3 as the first phosphor, the first wavelength-converted light 7 contains a large amount of fluorescent components in the near-infrared wavelength range (650 to 1000 nm), which is called the "biological window" and through which light easily penetrates a living body. Therefore, it was found that the light emitting devices using the phosphors of Examples 1 to 3 as the first phosphor increase the intensity of near-infrared light that penetrates a living body.

[0174] Comparative Example 2 (Preparation of phosphor) Nitride phosphors were synthesized using a preparation method using solid-state reactions. 0.997 ,EU 0.003 A nitride phosphor represented by the composition formula of AlSiN3 was synthesized. The following compound powders were used as the main raw materials when synthesizing the nitride phosphor. Calcium nitride (Ca3N2): Purity 2N, manufactured by Taiheiyo Cement Corporation Aluminum nitride (AlN): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd. Silicon nitride (Si3N4): 3N purity, manufactured by Denka Co., Ltd. Europium nitride (EuN): 2N purity, manufactured by Taiheiyo Cement Corporation

[0175] First, a compound with a stoichiometric composition (Ca 0.997 ,EU 0.003 The raw materials were weighed in a glove box with a N2 atmosphere to obtain AlSiN3. Next, the raw materials were dry mixed using a mortar and pestle to obtain the firing raw material.

[0176] The raw materials for firing were transferred to a boron nitride (BN) crucible with a lid, and fired in a pressurized atmosphere controlled electric furnace at 1600°C in a N2 (0.6 MPa) pressurized atmosphere for 2 hours. The fired product was then lightly crushed to obtain a phosphor of Comparative Example 2. Note that the sample after firing contained (Ca 0.997 ,EU 0.003 )AlSiN3 was confirmed by X-ray diffraction.

[0177] (Evaluation of luminescence lifetime) The luminescence lifetime of the phosphor was evaluated using a Quantaurus-Tau compact fluorescence lifetime measurement device (manufactured by Hamamatsu Photonics K.K.) The results are shown in FIG.

[0178] 9 shows the luminescence lifetime of Example 1. Note that FIG. 9 also shows the luminescence lifetimes of Example 2, Example 3, Comparative Example 1, and Comparative Example 2. Table 2 shows the time it takes for the intensity to reach 1 / 10 of the maximum intensity (1 / 10 afterglow): τ 1 / 10 Shows.

[0179] [Table 2]

[0180] (Summary of evaluation of luminescence lifetime) It was found that the phosphors of Examples 1 to 3 emit wavelength-converted light that contains more short-afterglow near-infrared components in the wavelength range beyond 710 nm than long-afterglow linear spectral components with maximum fluorescence intensity in the wavelength range of 680 to 710 nm. The long-lasting linear spectral component is Cr 3+ of, 2 T1 and 2 E → 4 A2) is a light component based on an electron energy transition (spin-forbidden transition). The short-lasting near-infrared component is 4 T2 → 4 This is the optical component based on the electron energy transition (spin-allowed transition) of A2. Therefore, it was found that a light-emitting device using the phosphors of Examples 1 to 3 as the first phosphor contains a large amount of near-infrared components, and when irradiated with high-density laser light, the fluorescent output saturation is low, making it easy to achieve high output.

[0181] [Example 4] (Production of sintered body) 1.0 g of the phosphor powder of Example 1 was molded under a pressure of 210 MPa using a hydraulic press to produce a green compact having a diameter of 13 mm. This green compact was fired in a box-type electric furnace in the atmosphere at 1400°C for 1 hour to obtain a sintered body of Example 4.

[0182] [Example 5] (Production of sintered body) 1.0 g of the phosphor powder of Example 2 was molded under a pressure of 210 MPa using a hydraulic press to produce a green compact having a diameter of 13 mm. This green compact was fired in a box-type electric furnace in the atmosphere at 1400°C for 1 hour to obtain a sintered body of Example 5.

[0183] [Example 6] (Production of sintered body) 1.0 g of the phosphor powder of Example 3 was molded under a pressure of 210 MPa using a hydraulic press to produce a green compact having a diameter of 13 mm. This green compact was fired in a box-type electric furnace in the atmosphere at 1400°C for 1 hour to obtain a sintered body of Example 6.

[0184] Comparative Example 3 (Production of sintered body) 0.5 g of the phosphor powder of Comparative Example 2 was molded under a pressure of 210 MPa using a hydraulic press to produce a green compact with a diameter of 13 mm. This green compact was fired in a pressurized atmosphere controlled electric furnace at 1700°C in a pressurized N2 (0.6 MPa) atmosphere for 2 hours to obtain a sintered body of Comparative Example 3.

[0185] (Evaluation of fluorescent output saturation) The fluorescent output saturation characteristics of the phosphor were measured using an integrating sphere, where blue LD light with a peak wavelength of 450 nm was irradiated onto the phosphor, and the light emission of the phosphor pellet was observed using a multi-channel spectrometer. The rated output of the blue LD light was changed from 0.93 W to 3.87 W. The irradiated area of ​​the phosphor was 0.785 mm 2 It was decided.

[0186] FIG. 10 shows the fluorescent output saturation characteristics of Examples 4 to 6 and Comparative Example 3. Cr 3+ The luminescence lifetime of the activated phosphor is Eu 2+ It was found that the luminescence lifetime was very long compared to that of the activated phosphor. 3+ It was found that the activated phosphor has a long luminous life and yet can maintain high luminous efficiency even in a region where the power density of the excitation light is high.

[0187] The contents of this embodiment have been described above using examples, but it will be obvious to those skilled in the art that this embodiment is not limited to these descriptions and that various modifications and improvements are possible. [Industrial Applicability]

[0188] According to the present disclosure, it is possible to provide a light emitting device that emits high-output light with a high proportion of near-infrared fluorescent components when excited by high-density laser light, and an electronic device using the same. [Explanation of symbols]

[0189] 1, 1A, 1B, 1C Medical light-emitting device (light-emitting device) 2. Solid-state light-emitting element (light source) 3. 3A Wavelength converter 4. First Phosphor 6 primary light 7. First wavelength converted light 8 Second Phosphor 9 Second wavelength converted light 11 Endoscopy 100 Endoscopy System

Claims

1. A light emitting device comprising: a light source that emits primary light; and a first phosphor that absorbs the primary light and converts it into first wavelength-converted light having a longer wavelength than the primary light, The primary light has a rated optical output of 3 W or more, The first wavelength-converted light is Cr ３＋ Fluorescence based on the electron energy transition of A light-emitting device in which the fluorescence spectrum of the first wavelength-converted light has a maximum fluorescence intensity in a wavelength region exceeding 710 nm.

2. The optical density of the primary light is 0.5 W / mm ２ The light emitting device of claim 1 , wherein the luminance is greater than 1.

3. The optical density of the primary light is 3.0 W / mm ２ The light emitting device according to claim 1 or 2, wherein the luminance exceeds 1.

4. 4. The light emitting device according to claim 1, wherein the fluorescence spectrum of the first wavelength-converted light has a maximum fluorescence intensity in a wavelength region exceeding 730 nm.

5. 5. The light emitting device according to claim 1, wherein the first wavelength-converted light has a 1 / 10 decay time of less than 1 ms.

6. 6. The light emitting device according to claim 1, wherein the 80% spectral width at the maximum fluorescence intensity peak of the first wavelength-converted light is 20 nm or more and less than 80 nm.

7. 7. The light emitting device according to claim 1, wherein a ratio of the fluorescence intensity at a wavelength of 780 nm to the maximum fluorescence intensity in the fluorescence spectrum of the first wavelength-converted light exceeds 30%.

8. The fluorescence spectrum of the first wavelength-converted light is ３＋ 8. The light emitting device of claim 1, wherein the light emitting device does not contain evidence of a linear spectral component resulting from an electronic energy transition of .

9. 9. The light emitting device according to claim 1, wherein the first phosphor has a garnet crystal structure.

10. The light emitting device according to any one of claims 1 to 9, further comprising a second phosphor that absorbs the primary light and converts it into second wavelength-converted light that has a longer wavelength than the primary light and is different from the first wavelength-converted light.

11. The first phosphor comprises two or more kinds of Cr ３＋ The light emitting device according to any one of claims 1 to 10, comprising an activated phosphor.

12. 12. The light emitting device according to claim 1, wherein the primary light is at least one of cool light having a maximum fluorescence intensity within a wavelength range of 400 nm or more and less than 500 nm, and warm light having a maximum fluorescence intensity within a wavelength range of 570 nm or more and less than 660 nm.

13. The light emitting device according to any one of claims 1 to 12, which is a medical light source or a medical illumination device.

14. The light emitting device according to any one of claims 1 to 12, which is a light source for a sensing system or an illumination system for a sensing system.

15. An electronic device comprising the light-emitting device according to claim 13 or 14.

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