Near-infrared light emitting device and biological information detection device provided with same

Abstract

A near-infrared light emitting device (10) has a solid-state light emitting element (1) and a wavelength conversion body (2) containing a phosphor, and emits two or more fluorescent components from one light output surface. The two or more fluorescent components include a first fluorescent component and a second fluorescent component that are positioned side by side in order from a short-wavelength side. The spectral shape of the first fluorescent component has a steeper slope in a long-wavelength region, which is a region having a longer wavelength than the fluorescent peak of the first fluorescent component, than in a short-wavelength region, which is a region having a shorter wavelength than the fluorescent peak of the first fluorescent component. The spectral shape of the second fluorescent component has a steeper slope in a short-wavelength region, which is a region having a shorter wavelength than the fluorescent peak of the second fluorescent component, than in a long-wavelength region, which is a region having a longer wavelength than the fluorescent peak of the second fluorescent component. The second fluorescent component has the fluorescence peak within a wavelength range of 780nm to1000 nm.

Description

Near-infrared light emitting device and biological information detecting device equipped with the same

[0001] The present invention relates to a near-infrared light emitting device and a biological information detecting device including the same.

[0002] Dual-wavelength spectrophotometry (Dual-wavelength spectrophotometry) has been used in various fields, including biochemistry, medicine, agriculture, and nutrition, to detect specific substances even when it is difficult to separate the sample into pure forms. Dual-wavelength spectrophotometry is also used to identify substances added to various foods, spoilage products, and pharmaceuticals.

[0003] The dual wavelength method measures the absorbance at the first wavelength, which is the maximum absorption wavelength, and at the second wavelength, which is set on the longer side, and then quantifies the concentration of the target substance from the difference in absorbance between the main and secondary wavelengths. For example, a pulse oximeter uses two types of light, red and infrared, to determine the proportion of hemoglobin in the blood that is bound to oxygen.

[0004] A known device for detecting biological information using such a two-wavelength method is described in Patent Document 1. Patent Document 1 discloses a biological information detection device for non-contact detection of biological information related to blood, such as blood oxygen saturation or hemoglobin concentration. The biological information detection device includes a light source that irradiates a living body with measurement light of multiple different wavelengths, and an irradiation angle adjustment unit serving as an irradiation position adjustment unit that adjusts the irradiation position of the light of multiple different wavelengths depending on the measurement distance to the living body. The biological information detection device further includes an imaging unit serving as a light receiving unit that receives reflected light from the living body, and a processing unit that calculates biological information based on the intensity of the reflected light. This biological information detection device detects biological information non-contact by irradiating the living body with measurement light of multiple different wavelengths at the same irradiation position and calculating the blood oxygen saturation or hemoglobin concentration based on the intensity of the reflected light from the irradiation position.

[0005] Patent No. 6832512

[0006] In the dual-wavelength method, two or more light sources are typically used to irradiate light of two different wavelengths. However, when multiple light sources with different wavelengths are arranged, the optical axes of each light source are different, which can cause uneven illumination of the light irradiated onto the measurement object, resulting in variations in the intensity balance depending on the illumination location. Furthermore, uneven illumination of the light irradiated onto the measurement object can have a negative impact on the measurement results.

[0007] The present invention has been made in view of the problems inherent in the conventional techniques, and an object of the present invention is to provide a near-infrared light-emitting device that can suppress uneven irradiation of light irradiated onto a measurement object even when irradiating light of two different wavelengths, and a biological information detection device equipped with the near-infrared light-emitting device.

[0008] In order to solve the above problems, a near-infrared light-emitting device according to a first aspect of the present invention is a near-infrared light-emitting device that includes a solid-state light-emitting element and a wavelength converter containing a phosphor, and emits two or more fluorescent components from a single light output surface. The two or more fluorescent components include a first fluorescent component and a second fluorescent component arranged in order from the shortest wavelength side, and the first fluorescent component and the second fluorescent component are fluorescence based on electronic energy transitions of transition metal ions. The spectral shape of the first fluorescent component is such that the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is steeper than the slope of the short-wavelength region. The spectral shape of the second fluorescent component is such that the slope of the short-wavelength region from the fluorescence peak of the second fluorescent component is steeper than the slope of the long-wavelength region. The emission intensity of the first fluorescent component at the long-wavelength end is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the emission intensity of the second fluorescent component at the short-wavelength end is 10% of the maximum emission intensity. The second fluorescent component has a fluorescent peak within a wavelength range of 780 nm to 1000 nm.

[0009] A near-infrared light-emitting device according to a second aspect of the present invention is a near-infrared light-emitting device that includes a solid-state light-emitting element and a wavelength converter containing a phosphor, and emits two or more fluorescent components from a single light output surface. The near-infrared light-emitting device further includes a notch filter that controls wavelength-converted light converted by the wavelength converter. The fluorescent components include a first fluorescent component on the short wavelength side and a second fluorescent component on the long wavelength side, sandwiching a blocking region controlled by the notch filter. The first fluorescent component and the second fluorescent component are fluorescence based on electronic energy transition of a transition metal ion. The second fluorescent component has a fluorescence peak in a wavelength range of 780 nm to 1000 nm.

[0010] A biological information detecting device according to a third aspect of the present invention includes a near-infrared light emitting device.

[0011] FIG. 1 is a diagram showing the relationship between the irradiation position of a measurement object and the emission spectrum of irradiated light when two types of light-emitting diodes with different wavelengths of irradiated light are used as a light source for the two-wavelength method. FIG. 2 is a diagram showing the relationship between the irradiation position of a measurement object and the emission spectrum of irradiated light when a light-emitting device including a near-infrared phosphor is used as a light source for the two-wavelength method. FIG. 3(a) is a schematic diagram showing an example of the configuration of a near-infrared light-emitting device according to this embodiment. FIG. 3(b) is a diagram showing an example of the spectral distribution of output light emitted from the near-infrared light-emitting device according to this embodiment. FIG. 3(c) is a diagram showing an example of the spectral distribution of wavelength-converted light emitted from a wavelength converter and before passing through a notch filter in a near-infrared light-emitting device according to this embodiment. FIG. 4 is a diagram showing an example of the spectral distribution of output light emitted from a near-infrared light-emitting device according to this embodiment. FIG. 5 is a schematic diagram showing an example of a biological information detection device according to this embodiment.

[0012] The near-infrared light emitting device according to the present embodiment and the biological information detecting device including the near-infrared light emitting device will be described in detail 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.

[0013] [Near-infrared Light-Emitting Device] In the dual-wavelength method, at least two light sources are generally used to irradiate light of two different wavelengths. For example, as shown in FIG. 1, a light-emitting device is used in which two types of light-emitting diodes (LEDs) with different output light wavelengths are arranged in parallel with the object to be measured. An imaging camera is then placed between the two types of light-emitting diodes to detect reflected light from the object to be measured. In this light-emitting device, one of the light-emitting diodes is a near-infrared light-emitting diode that emits output light with a peak wavelength of 780 nm. The other light-emitting diode is also a near-infrared light-emitting diode that emits output light with a peak wavelength of 850 nm. Both of these light-emitting diodes emit sharp output light with narrow half-widths.

[0014] When near-infrared light is irradiated onto the face of a person being measured using the light-emitting device shown in FIG. 1 , both near-infrared light with a wavelength of 780 nm and near-infrared light with a wavelength of 850 nm are irradiated onto the face. Here, the light irradiated onto the left half of the person's face has a higher irradiation intensity of the near-infrared light with a wavelength of 780 nm than the near-infrared light with a wavelength of 850 nm. In contrast, the light irradiated onto the right half of the person's face has a higher irradiation intensity of the near-infrared light with a wavelength of 850 nm than the near-infrared light with a wavelength of 780 nm. Thus, when multiple light sources with different wavelengths are arranged, the optical axes of the light sources are different, resulting in uneven irradiation of the near-infrared light irradiated onto the person's face, resulting in a phenomenon in which the intensity balance varies depending on the irradiation location. Furthermore, these two types of light-emitting diodes have different temperature characteristics, which creates the problem of the balance of irradiation intensity changing depending on the ambient temperature.

[0015] To suppress such uneven illumination of the measurement target, the phosphor method shown in FIG. 2 has attracted attention as an alternative to the LED method shown in FIG. 1. The light-emitting device shown in FIG. 2 includes a solid-state light-emitting element and a wavelength converter containing a near-infrared phosphor. The primary light emitted from the solid-state light-emitting element is wavelength-converted by the near-infrared phosphor, and the near-infrared light is then emitted from the light output surface. An imaging camera is positioned near the light-emitting device to detect reflected light from the measurement target. The near-infrared light emitted from this light-emitting device is broad fluorescence with a large half-width. The target substance can be quantified by using two fluorescent components of this broad fluorescence. For example, the light-emitting device shown in FIG. 2 quantifies the target substance using a fluorescent component with a wavelength near 780 nm and a fluorescent component with a wavelength near 850 nm.

[0016] Here, when near-infrared light is irradiated onto the face of a person being measured using the light-emitting device shown in FIG. 2, both the left and right halves of the person's face are irradiated with near-infrared light with a consistent intensity balance. In other words, in the light-emitting device shown in FIG. 2, near-infrared light is emitted from a single light output surface, resulting in a single optical axis. Furthermore, even if multiple solid-state light-emitting elements and wavelength converters are used, the light output surface from which near-infrared light is emitted is a single optical axis, resulting in a consistent optical axis. Therefore, the intensity balance of near-infrared light is consistent at any location on the measurement object, and by detecting reflected light of two wavelengths from the measurement object, the target substance can be quantified with high accuracy. Furthermore, the light-emitting device shown in FIG. 2 uses a wavelength converter containing a near-infrared phosphor, and since the wavelength converter has a consistent temperature characteristic, the intensity balance of the irradiated light is unlikely to change even when the ambient temperature changes.

[0017] As described above, unlike the LED-based light-emitting device of FIG. 1, the phosphor-based light-emitting device of FIG. 2 has the advantage that the optical axis of the near-infrared light irradiated onto the measurement object is the same, and the intensity balance is constant at any location on the measurement object.

[0018] Here, the LED-based light-emitting device of Fig. 1 and the phosphor-based light-emitting device of Fig. 2 emit, for example, light with wavelengths of around 780 nm and light with wavelengths of around 850 nm. The light-emitting device of Fig. 2 also emits fluorescence between wavelengths of 780 nm and 850 nm, i.e., fluorescence in the wavelength range of 790 nm to 840 nm. Furthermore, since the near-infrared light emitted from the light-emitting device of Fig. 2 has a fluorescence peak in the wavelength range of 790 nm to 840 nm, the fluorescence with wavelengths of 790 nm to 840 nm is highly intense.

[0019] Although not used in such quantification using the two-wavelength method, when a person to be measured is irradiated with high-intensity near-infrared light, the person may experience discomfort due to glare and / or thermal discomfort, for example. Therefore, when irradiating a person to be measured with near-infrared fluorescent light, it is preferable to remove light of unnecessary wavelengths other than the two wavelengths used in the quantitative measurement.

[0020] The light emitting device of this embodiment is a device that can suppress the emission of unnecessary fluorescence while suppressing unevenness in the light irradiated onto the object to be measured, even when irradiating light of two different wavelengths.

[0021] 3(a), the near-infrared light emitting device 10 of this embodiment includes a solid-state light emitting element 1 that emits primary light, and a wavelength converter 2 that includes a phosphor that has the property of absorbing the primary light and converting it into a light component with a longer wavelength than the primary light. The near-infrared light emitting device 10 further includes an optical member 3 that has the property of attenuating part of the fluorescence emitted by the phosphor contained in the wavelength converter 2 but transmitting the rest of the fluorescence.

[0022] The solid-state light-emitting element 1 is mounted on the surface (main surface) 4a of the substrate 4. The solid-state light-emitting element 1 can be, for example, a light-emitting diode (LED) or a laser diode. For example, by using an LED module or laser diode that emits high-energy light of 1 W or more, a near-infrared light-emitting device can be expected to have an optical output of several hundred mW. Furthermore, by using an LED module that emits high-energy light of 3 W or more or 10 W or more, a near-infrared light-emitting device can be expected to have an optical output of several W. Furthermore, by using an LED module that emits high-energy light of 30 W or more, a near-infrared light-emitting device can be expected to have an optical output of more than 10 W. Furthermore, by using an LED module that emits high-energy light of 100 W or more, a near-infrared light-emitting device can be expected to have an optical output of more than 30 W.

[0023] When a laser diode is used as the solid-state light-emitting element 1 and the primary light is converted into laser light, a high-density spot light is irradiated onto the wavelength converter 2. Therefore, the obtained near-infrared light-emitting device can be used as a high-output point light source, which can expand the range of industrial applications of solid-state lighting. Examples of such laser diodes that can be used include edge-emitting lasers (EELs) and vertical-cavity surface-emitting lasers (VCSELs).

[0024] The primary light emitted by the solid-state light-emitting element 1 is preferably blue light having a maximum intensity in the wavelength region of 435 nm or more and less than 480 nm. Solid-state light-emitting elements that emit high-output, high-efficiency blue light are easy to procure, which makes it easy to increase the output and efficiency of near-infrared light-emitting devices and is also advantageous for industrial production of near-infrared light-emitting devices.

[0025] The number of solid-state light-emitting elements 1 mounted on the substrate 4 is not particularly limited and may be one or more. Having a plurality of solid-state light-emitting elements 1 makes it easier to increase the output of primary light, resulting in a near-infrared light-emitting device advantageous for achieving high output. The number of solid-state light-emitting elements 1 is not particularly limited and may be appropriately selected from, for example, 9 or more, 16 or more, 25 or more, 36 or more, 49 or more, 64 or more, 81 or more, or 100 or more. The upper limit of the number is also not particularly limited and may be appropriately selected from, for example, 9 or less, 16 or less, 25 or less, 36 or less, 49 or less, 64 or less, 81 or less, or 100 or less.

[0026] In the near-infrared light emitting device 10, the solid-state light emitting element 1 is preferably a surface-emitting light source of a surface-emitting type, which can suppress variations in the intensity distribution and color tone of the primary light irradiated onto the wavelength converter 2, thereby providing a near-infrared light emitting device advantageous in suppressing variations in the intensity distribution of the output light.

[0027] The material of the substrate 4 is not particularly limited, but may be, for example, a metal substrate, specifically, an aluminum substrate, or a ceramic substrate, specifically, an alumina substrate.

[0028] The wavelength converter 2 is laminated on the upper surface of the solid-state light-emitting element 1. The wavelength converter 2 preferably contains a near-infrared phosphor. The near-infrared phosphor absorbs the primary light emitted by the solid-state light-emitting element 1 and converts it into wavelength-converted light containing near-infrared light. Such a near-infrared phosphor is preferably a phosphor that emits near-infrared light having a fluorescence peak in a wavelength range of 730 nm or more and less than 2500 nm, and more preferably a phosphor that emits near-infrared light having a fluorescence peak in a wavelength range of 780 nm or more and less than 2500 nm. Furthermore, the near-infrared phosphor is preferably a phosphor that emits near-infrared light having a fluorescence peak in a wavelength range of 730 nm or more and less than 1000 nm, and more preferably a phosphor that emits near-infrared light having a maximum intensity in a wavelength range of 780 nm or more and less than 1000 nm. This allows for easy wavelength conversion of the primary light emitted by the solid-state light-emitting element into a near-infrared light component, which is advantageous, for example, in obtaining the near-infrared light component required for measurement light.

[0029] As the near-infrared phosphor, for example, various inorganic phosphors known for use as near-infrared light sources can be used. Specifically, as the near-infrared phosphor, a phosphor activated with at least one of a transition metal ion and a rare earth ion and emitting fluorescence containing a near-infrared light component can be used. The transition metal ion is Ti, ３＋ , V ４＋ , Cr ４＋ , V ３＋ , Cr ３＋ , V ２＋ , Mn ４＋ , Fe ３＋ , Co ３＋ , Co ２＋ and Ni ２＋ The rare earth ion is preferably at least one selected from the group consisting of Nd ３＋ , Eu ２＋ , Ho ３＋ , Er ３＋ , Tm ３＋ and Yb ３＋ It is preferable that the near-infrared phosphor is at least one selected from the group consisting of: and it is preferable that the near-infrared phosphor is an oxide, sulfide, nitride, halide, oxysulfide, oxynitride, or oxyhalide containing the fluorescent ion.

[0030] The near-infrared phosphor contained in the wavelength converter 2 can be at least one selected from the group consisting of halophosphates, phosphates, halosilicates, silicates, aluminates, aluminosilicates, borates, germanates, silicon nitrides, alumino-nitride silicates, silicon oxynitride salts, and alumino-nitride silicates activated with the above-mentioned activators. Therefore, the phosphor to be used can be appropriately selected from these phosphors to suit the lighting design.

[0031] Here, the activator of the near-infrared phosphor contained in the wavelength converter 2, i.e., the fluorescent ions, are Cr ３＋ It is preferable that Cr ３＋ By using Cr, which absorbs visible light, especially blue or red light, and converts it into a deep red to near infrared light component, it is possible to obtain a phosphor that has the property of absorbing visible light, especially blue or red light, and converting it into a deep red to near infrared light component. In addition, depending on the type of host to which the activator is added, it is easy to change the light absorption peak wavelength and fluorescence peak wavelength of the phosphor, which is advantageous in changing the shape of the excitation spectrum and the fluorescence spectrum. Furthermore, Cr, which absorbs blue or red light and converts it into a near infrared fluorescent component, can be used. ３＋ Therefore, not only does it broaden the range of choices for the solid-state light-emitting element 1 that emits primary light, but it also makes it easy to change the peak wavelength of the fluorescence emitted by the phosphor, resulting in a near-infrared light-emitting device 10 that is advantageous in controlling the spectral distribution of the output light.

[0032] The fluorescent ions are Cr ３＋ The phosphor is not particularly limited as long as it absorbs excitation light (primary light) and converts it into fluorescence with a wavelength longer than that of the excitation light. ３＋ However, Cr ３＋ The activated phosphor is preferably a phosphor based on a composite metal oxide, which is easy to manufacture.

[0033] Cr ３＋ The activator phosphor is preferably a composite oxide phosphor having a garnet-type crystal structure, which has a proven track record in practical use. ３＋ The activated garnet phosphor is Y ３ Al ２ (AlO ４ ) ３ : Cr３＋ 、La ３ Al ２ (AlO ４ ) ３ :Cr ３＋ 、Gd ３ Al ２ (AlO ４ ) ３ :Cr ３＋ 、Y ３ Ga ２ (AlO ４ ) ３ :Cr ３＋ 、La ３ Ga ２ (AlO ４ ) ３ :Cr ３＋ 、Gd ３ Ga ２ (AlO ４ ) ３ :Cr ３＋ 、Y ３ Sc ２ (AlO ４ ) ３ :Cr ３＋ 、La ３ Sc ２ (AlO ４ ) ３ :Cr ３＋ 、Gd ３ Sc ２ (AlO ４ ) ３ :Cr ３＋ 、Y ３ Ga ２ (GaO ４ ) ３ :Cr ３＋ 、La ３ Ga ２ (GaO ４ ) ３ :Cr ３＋ 、(Gd,La) ３ Ga ２ (GaO ４ ) ３ :Cr ３＋ 、Gd ３ Ga ２ (GaO ４ ) ３ :Cr ３＋ 、Y ３ Sc ２ (GaO ４ )３ : Cr ３＋ , La ３ Sc ２ (GaO ４ ) ３ : Cr ３＋ , Gd ３ Sc ２ (GaO ４ ) ３ : Cr ３＋ , and (Gd, La) ３ (Ga, Sc) ２ (GaO ４ ) ３ : Cr ３＋ It can be at least one selected from the group consisting of Cr ３＋ The activated garnet phosphor may be a solid solution containing these phosphors as end members.

[0034] The near-infrared phosphor contained in the wavelength converter 2 is Y ４ CdMo ３ O １６ : Yb ３＋ , K. ３ LuSi ２ O ７ :Eu ２＋ , CaO:Eu ２＋ , Sr ２－ｙ Ca ｙ InSbO ６ : Fe ３＋ , La ３ Ga ５ GeO １４ : Cr ３＋ , ScBO ３ : Cr ３＋ , and Ga ２－ｘ Sc ｘ O ３ : Cr ３＋ It may be at least one selected from the group consisting of:

[0035] Here, the spectral distribution of near-infrared light emitted from the near-infrared phosphor preferably has a single peak when the spectral intensity at every 10 nm wavelength is displayed as a histogram. In this specification, "single peak" refers to a distribution state in which the histogram has a single peak. By making the spectral distribution single-peaked, the near-infrared light components are concentrated in a specific wavelength range, resulting in a near-infrared light emitting device that is advantageous for increasing the output and efficiency of near-infrared light.

[0036] The wavelength converter 2 can be produced by sealing the phosphor with a sealing material. The sealing material is preferably at least one of an organic material and an inorganic material, particularly at least one of a transparent (translucent) organic material and a transparent (translucent) inorganic material. Examples of sealing materials for organic materials include transparent organic materials such as silicone resin. Examples of sealing materials for inorganic materials include transparent inorganic materials such as low-melting-point glass.

[0037] The wavelength converter 2 can be a sintered body made by sintering a phosphor and having a plurality of voids therein. Furthermore, the wavelength converter 2 can be a ceramic body made by sintering a phosphor and not having a plurality of voids therein. When the wavelength converter 2 is a sintered body or ceramic body of this kind, the wavelength converter 2 can be easily manufactured and handled, making it suitable for industrial production. Furthermore, when the wavelength converter 2 is a sintered body or ceramic body, fluorescent ions are distributed at a high density in the thickness direction, making it easy to relatively increase the light absorptance of the wavelength converter, and thus enabling a further increase in the fluorescent output rate.

[0038] The near-infrared light emitting device 10 includes an optical member 3, which is disposed on the surface (top surface) of the wavelength converter 2 opposite to the solid-state light emitting element 1. As shown in Fig. 3(a) , the optical member 3 covers the entire top surface of the wavelength converter 2. The optical member 3 has the property of attenuating part of the fluorescence emitted by the near-infrared phosphor contained in the wavelength converter 2, but transmitting the remaining fluorescence.

[0039] In the near-infrared light emitting device 10, the optical member 3 is preferably a member made solely of inorganic materials. Since an optical member 3 made solely of inorganic materials is excellent in heat resistance and durability, a near-infrared light emitting device with improved heat resistance and durability can be obtained.

[0040] Furthermore, the optical member 3 preferably has a dielectric multilayer structure, which utilizes the optical interference effect observed in a multilayer structure of dielectrics with different dielectric constants to obtain optical properties that attenuate part of the fluorescence emitted by the near-infrared phosphor while transmitting the remaining fluorescence.

[0041] The optical element 3 is preferably an optical interference filter. An optical interference filter is formed by depositing a dielectric thin film on the surface of a substrate. Furthermore, the dielectric thin film utilizes the fact that the light transmission characteristics change due to interference of reflections occurring at the interfaces between air and a dielectric, between a dielectric and a substrate, and between different dielectrics. By using such an optical interference filter, it is possible to reduce the transmittance of part of the fluorescence emitted by the near-infrared phosphor while relatively increasing the transmittance of the remaining fluorescence. Furthermore, optical interference filters are easy to modify in design and obtain, making it relatively easy to configure a desired light-emitting device.

[0042] It is more preferable that the optical element 3 is a notch filter. A notch filter is also called a bandstop filter or a band-rejection filter. A notch filter has the property of attenuating light in a specific wavelength band (stop band, blocking region) to a very low level and transmitting light of most other wavelengths with little loss of intensity. By using a notch filter as the optical element 3, it is possible to remove light of unnecessary wavelengths other than the two wavelengths when irradiating the measurement target with near-infrared fluorescence.

[0043] The operation of the near-infrared light-emitting device 10 of this embodiment having such a configuration will be described. As shown in Fig. 3(a) , in the near-infrared light-emitting device 10, first, when power is applied to the solid-state light-emitting element 1 of the near-infrared light-emitting device 10, primary light is emitted upward from the solid-state light-emitting element 1. The emitted primary light passes through the wavelength converter 2, and at this time, a portion of the primary light is absorbed by fluorescent ions of the near-infrared phosphor contained in the wavelength converter 2. Then, the primary light is converted into near-infrared light as wavelength-converted light by electron energy transition of the fluorescent ions, and is emitted from the phosphor.

[0044] The near-infrared fluorescence emitted from the near-infrared phosphor preferably has a broad spectral distribution with a large half-width and a single peak, as shown in FIG. 3(c).

[0045] The near-infrared light emitted from the wavelength converter 2 then reaches the optical member 3. As described above, the optical member 3 has the property of attenuating a portion of the near-infrared light and transmitting the remaining fluorescence. Therefore, the near-infrared fluorescence incident on one surface 3a of the optical member 3 is partially attenuated by the optical member 3, while the remaining fluorescence is transmitted. Then, near-infrared light having a spectral distribution as shown in FIG. 3(b) is output from the other surface 3b of the optical member 3. In this way, the near-infrared light emitting device 10 can output output light in which a portion of the uni-peaked near-infrared fluorescence emitted from the wavelength converter 2 is attenuated.

[0046] Here, the output light emitted from the near-infrared light emitting device 10 according to this embodiment will be described in detail.

[0047] The near-infrared light emitting device 10 emits output light from the other surface 3b of the optical member 3, and therefore emits fluorescent components from one light output surface. As a result, in the near-infrared light emitting device 10, the optical axis of the fluorescent components becomes one.

[0048] As described above, since the optical member 3 cuts a portion of the near-infrared light emitted from the wavelength converter 2, the output light has at least two fluorescent components, as shown in Fig. 4. The two fluorescent components are a first fluorescent component and a second fluorescent component, which are positioned in order from the shortest wavelength side. Note that since the near-infrared phosphor contains a transition metal as an activator, the first fluorescent component and the second fluorescent component are fluorescence based on the electronic energy transition of the transition metal ion.

[0049] In the spectral distribution shown in FIG. 4, the first fluorescent component has a fluorescent peak wavelength of 804 nm, and the second fluorescent component has a fluorescent peak wavelength of 857 nm.

[0050] The spectral shape of the first fluorescent component has a steeper slope in the long-wavelength region from the fluorescence peak of the first fluorescent component than in the short-wavelength region. Specifically, the short-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, and the long-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the maximum emission intensity. More specifically, the short-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 713 nm, and the long-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 813 nm. As shown in FIG. 4 , on the shorter-wavelength side of the fluorescence peak of the first fluorescent component, the emission intensity increases continuously from wavelength 713 nm to wavelength 804 nm, but the slope is gentle. In contrast, on the longer wavelength side than the fluorescence peak of the first fluorescent component, the emission intensity decreases continuously from wavelength 804 nm to wavelength 813 nm, but the gradient is steep.

[0051] In contrast, the spectral shape of the second fluorescent component has a steeper slope in the short-wavelength region from the fluorescence peak of the second fluorescent component than in the long-wavelength region. Specifically, the short-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the long-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the maximum emission intensity. More specifically, the short-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 847 nm, and the long-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 1011 nm. As shown in FIG. 4 , on the shorter-wavelength side of the fluorescence peak of the second fluorescent component, the emission intensity continuously increases from wavelength 847 nm to wavelength 857 nm, but the slope is steep. In contrast, on the longer wavelength side than the fluorescence peak of the second fluorescent component, the emission intensity decreases continuously from the wavelength of 857 nm to the wavelength of 1011 nm, but the slope is gentle.

[0052] The emission intensity between the long wavelength end of the first fluorescent component and the short wavelength end of the second fluorescent component is 10% or less of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component.

[0053] As described above, in the near-infrared light-emitting device 10 of this embodiment, the first fluorescent component and the second fluorescent component are clearly separated. Furthermore, the emission intensity between the first fluorescent component and the second fluorescent component is less than 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component. Therefore, for example, a target substance can be quantified by a two-wavelength method using a fluorescent component with a wavelength of approximately 770 nm and a fluorescent component with a wavelength of approximately 880 nm. Furthermore, the fluorescent component between the first fluorescent component and the second fluorescent component, which is not used in quantification using the two-wavelength method, is significantly reduced, thereby suppressing adverse effects, such as discomfort, on the measurement subject.

[0054] The first fluorescent component emitted by the near-infrared light-emitting device 10 will be described in more detail. In the spectral shape of the first fluorescent component, the maximum value of the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is preferably 8% / nm or more, when the maximum emission intensities at the fluorescence peaks of the first fluorescent component and the second fluorescent component are taken as 100%. In other words, the maximum value of the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is preferably 8% or more per nm of wavelength, when the maximum emission intensity is taken as 100%. In contrast, the maximum value of the slope of the short-wavelength region from the fluorescence peak of the first fluorescent component is preferably less than 8% / nm, when the maximum emission intensity is taken as 100%. In other words, the maximum value of the slope of the short-wavelength region from the fluorescence peak of the first fluorescent component is preferably less than 8% per nm of wavelength, when the maximum emission intensity is taken as 100%. Such a spectral distribution cuts out the fluorescent components between the first fluorescent component and the second fluorescent component while increasing the intensity of the measurement light on the short wavelength side in the two-wavelength method, thereby improving the measurement accuracy of the target substance while suppressing adverse effects on the measurement target.

[0055] In the spectral distribution of the first fluorescent component, the maximum value of the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is preferably 10% / nm or more, when the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component is taken as 100%. Also, the maximum value of the slope of the short-wavelength region from the fluorescence peak of the first fluorescent component is preferably less than 5% / nm, when the maximum emission intensity is taken as 100%.

[0056] The second fluorescent component emitted by the near-infrared light-emitting device 10 will be described in more detail. In the spectral shape of the second fluorescent component, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the short wavelength region is preferably 8% / nm or more, when the maximum emission intensities at the fluorescence peaks of the first fluorescent component and the second fluorescent component are taken as 100%. In other words, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the short wavelength region is preferably 8% or more per nm of wavelength, when the maximum emission intensity is taken as 100%. In contrast, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the long wavelength region is preferably less than 8% / nm, when the maximum emission intensity is taken as 100%. In other words, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the long wavelength region is preferably less than 8% per nm of wavelength, when the maximum emission intensity is taken as 100%. Such a spectral distribution cuts out fluorescent components between the first and second fluorescent components while increasing the intensity of the measurement light on the long wavelength side in the two-wavelength method, thereby improving the measurement accuracy of the target substance while suppressing adverse effects on the measurement target.

[0057] In the spectral distribution of the second fluorescent component, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the short wavelengths is preferably 10% / nm or more, when the maximum emission intensities at the fluorescence peaks of the first and second fluorescent components are taken as 100%. Also, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the long wavelengths is preferably less than 5% / nm, when the maximum emission intensity is taken as 100%.

[0058] Furthermore, the short-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the long-wavelength end of the first fluorescent component is set to a wavelength that is 10% of the maximum emission intensity. On the short-wavelength side of the first fluorescent component, the wavelength range from the short-wavelength end of the first fluorescent component to the fluorescence peak of the first fluorescent component is preferably 40 nm or more. Furthermore, on the long-wavelength side of the first fluorescent component, the wavelength range from the fluorescence peak of the first fluorescent component to the long-wavelength end of the first fluorescent component is preferably 15 nm or less. Even with this spectral distribution, the intensity of the measurement light on the short-wavelength side in the dual-wavelength method is increased while cutting out fluorescent components between the first and second fluorescent components, thereby improving the measurement accuracy of the target substance while suppressing adverse effects on the measurement target.

[0059] Furthermore, the short-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the long-wavelength end of the second fluorescent component is set to a wavelength that is 10% of the maximum emission intensity. On the short-wavelength side of the second fluorescent component, the wavelength range from the short-wavelength end of the second fluorescent component to the fluorescence peak of the second fluorescent component is preferably 15 nm or less. Furthermore, on the long-wavelength side of the second fluorescent component, the wavelength range from the fluorescence peak of the second fluorescent component to the long-wavelength end of the second fluorescent component is preferably 40 nm or more. Even with this spectral distribution, the intensity of the measurement light on the long-wavelength side in the dual-wavelength method is increased while cutting out fluorescent components between the first and second fluorescent components, thereby improving the measurement accuracy of the target substance while suppressing adverse effects on the measurement target.

[0060] In the near-infrared light-emitting device 10, the second fluorescent component preferably has a fluorescence peak within a wavelength range of 780 nm to 1000 nm. When the fluorescence peak of the second fluorescent component is within this wavelength range, the measurement light on the long wavelength side can be near-infrared light.

[0061] In the near-infrared light-emitting device 10, the first fluorescent component is located on the shorter wavelength side than the second fluorescent component and therefore includes at least one of red light and near-infrared light. Therefore, it is preferable that the first fluorescent component has a fluorescence peak within a wavelength range of 600 nm to 900 nm. By having the fluorescence peak of the first fluorescent component within this wavelength range, the measurement light on the shorter wavelength side can be at least one of red light and near-infrared light.

[0062] In the near-infrared light-emitting device 10, the first fluorescent component and the second fluorescent component are preferably fluorescence based on the electronic energy transition of the same transition metal ion, and are preferably fluorescence based on a dd transition or an fd transition. As described above, the near-infrared fluorescence emitted from the near-infrared phosphor of the wavelength converter 2 preferably has a broad spectral distribution with a large half-width and is also preferably unimodal. Therefore, the near-infrared phosphor contains a transition metal ion as an activator, and the fluorescence emitted from the near-infrared phosphor is preferably fluorescence based on the electronic energy transition of the transition metal ion, and is preferably fluorescence based on a dd transition or an fd transition. Note that if the fluorescence emitted from the transition metal ion is fluorescence based on an ff transition, the fluorescence will have a narrow half-width and a sharp spectral distribution. Therefore, it is preferable that the fluorescence emitted from the transition metal ion is not fluorescence based on an ff transition.

[0063] In the near-infrared light-emitting device 10, the wavelength difference between the long-wavelength end wavelength of the first fluorescent component and the short-wavelength end wavelength of the second fluorescent component is preferably 20 nm or more and 100 nm or less. The long-wavelength end wavelength of the first fluorescent component is set to a wavelength that is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component. The short-wavelength end wavelength of the second fluorescent component is set to a wavelength that is 10% of the maximum emission intensity. Furthermore, it is preferable that the wavelength difference between the long-wavelength end wavelength of the first fluorescent component and the short-wavelength end wavelength of the second fluorescent component be within the above range. This allows the first fluorescent component and the second fluorescent component to be clearly separated, making it suitable for use in the two-wavelength method.

[0064] In the near-infrared light-emitting device 10, it is preferable that the two or more fluorescent components are emitted from the same phosphor. In other words, it is preferable that the first fluorescent component and the second fluorescent component are derived from the emission of the same phosphor. This makes it easier to obtain fluorescence with a spectral distribution such as that shown in FIG. 4, making it suitable for use in the two-wavelength method.

[0065] In the near-infrared light-emitting device 10, the first fluorescent component preferably contains a light component in a wavelength range of 600 nm or more and less than 900 nm. By including a fluorescent component in this range in the first fluorescent component, the measurement light on the short wavelength side can be at least one of red light and near-infrared light.

[0066] In the near-infrared light emitting device 10, the first fluorescent component and the second fluorescent component are fluorescent components based on the electron energy transition of a transition metal ion, and the transition metal ion is Cr ３＋ , Cr ４＋ , Fe ３＋ and Eu ２＋ In this case, the near-infrared fluorescence emitted from the near-infrared phosphor of the wavelength converter 2 has a broad spectral distribution with a large half-width and tends to be single-peaked. Therefore, it is easy to obtain fluorescence with the spectral distribution shown in Figure 4, and therefore it can be suitably used in the two-wavelength method.

[0067] In the above description, the emission intensity at the long wavelength end of the first fluorescent component is 10% of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, and the emission intensity at the short wavelength end of the first fluorescent component is also 10% of the maximum emission intensity. Similarly, the emission intensity at the long wavelength end of the second fluorescent component is 10% of the maximum emission intensity, and the emission intensity at the short wavelength end of the second fluorescent component is also 10% of the maximum emission intensity. However, the emission intensity at the long wavelength end of the first fluorescent component may also be 5% of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, and the emission intensity at the short wavelength end of the first fluorescent component may also be 5% of the maximum emission intensity. Similarly, the emission intensity at the long wavelength end of the second fluorescent component may also be 5% of the maximum emission intensity, and the emission intensity at the short wavelength end of the second fluorescent component may also be 5% of the maximum emission intensity. Alternatively, the emission intensity at the long wavelength end of the first fluorescent component may be 3% of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, and the emission intensity at the short wavelength end of the first fluorescent component may also be 3% of the maximum emission intensity. Similarly, the emission intensity at the long wavelength end of the second fluorescent component may be 3% of the maximum emission intensity, and the emission intensity at the short wavelength end of the second fluorescent component may also be 3% of the maximum emission intensity.

[0068] Furthermore, the overall emission intensity between the long wavelength end of the first fluorescent component and the short wavelength end of the second fluorescent component is 10% or less of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, but the overall emission intensity between the long wavelength end of the first fluorescent component and the short wavelength end of the second fluorescent component may be 5% or less, or even 3% or less, of the maximum emission intensity.

[0069] Among the fluorescent components emitted by the near-infrared light-emitting device 10, the emission intensity of the fluorescence peak of the first fluorescent component may be greater than the emission intensity of the fluorescence peak of the second fluorescent component. Conversely, the emission intensity of the fluorescence peak of the first fluorescent component may be smaller than the emission intensity of the fluorescence peak of the second fluorescent component. Furthermore, the difference between the emission intensity of the fluorescence peak of the first fluorescent component and the emission intensity of the fluorescence peak of the second fluorescent component is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less. When the difference between the emission intensity of the fluorescence peak of the first fluorescent component and the emission intensity of the fluorescence peak of the second fluorescent component is small, the difference in intensity between the two measurement lights used in the two-component method tends to be small, thereby improving the measurement accuracy of the target substance.

[0070] When quantitatively analyzing a target substance using the near-infrared light-emitting device 10 by the dual-wavelength method, the wavelengths of the measurement light used can be, for example, around 770 nm and around 880 nm. However, this is not limited to such an embodiment, and the wavelengths of the measurement light can be around 610 nm and around 880 nm. Furthermore, the wavelengths of the measurement light can be around 675 nm and around 840 nm. Furthermore, the wavelengths of the measurement light can be around 630 nm and around 850 nm. Furthermore, the wavelengths of the measurement light can be around 660 nm and around 850 nm. Furthermore, the wavelengths of the measurement light can be around 780 nm and around 905 nm.

[0071] As described above, the near-infrared light-emitting device 10 of this embodiment is a near-infrared light-emitting device that includes a solid-state light-emitting element 1 and a wavelength converter 2 containing a phosphor, and emits two or more fluorescent components from a single light output surface. The two or more fluorescent components include a first fluorescent component and a second fluorescent component arranged in order from the shortest wavelength side, and the first fluorescent component and the second fluorescent component are fluorescent components based on electronic energy transitions of transition metal ions. The spectral shape of the first fluorescent component is such that the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is steeper than the slope of the short-wavelength region, and the spectral shape of the second fluorescent component is such that the slope of the short-wavelength region from the fluorescence peak of the second fluorescent component is steeper than the slope of the long-wavelength region. Furthermore, the emission intensity at the long-wavelength end of the first fluorescent component is 10% of the maximum emission intensity at the fluorescence peaks of the first fluorescent component and the second fluorescent component, and the emission intensity at the short-wavelength end of the second fluorescent component is 10% of the maximum emission intensity. The second fluorescent component has a fluorescent peak within the wavelength range of 780 nm to 1000 nm.

[0072] Furthermore, the near-infrared light-emitting device 10 of this embodiment is a near-infrared light-emitting device that includes a solid-state light-emitting element 1 and a wavelength converter 2 containing a phosphor, and emits two or more fluorescent components from a single light output surface. The near-infrared light-emitting device 10 further includes a notch filter that controls the wavelength-converted light converted by the wavelength converter. The fluorescent components include a first fluorescent component on the short wavelength side and a second fluorescent component on the long wavelength side, sandwiching a blocking region controlled by the notch filter. The first fluorescent component and the second fluorescent component are fluorescence based on the electron energy transition of a transition metal ion. The second fluorescent component has its fluorescence peak within a wavelength range of 780 nm to 1000 nm.

[0073] Since the near-infrared light-emitting device 10 emits fluorescent components from a single light output surface, the optical axes of the fluorescent components are unified, resulting in a consistent intensity balance at any location on the measurement object. Furthermore, the output light emitted from the near-infrared light-emitting device 10 contains two fluorescent components, the spectral distributions of which have characteristic shapes as shown in Figure 4. Therefore, while the target substance can be accurately quantified using the two-wavelength method, the fluorescent component between the first and second fluorescent components is significantly cut off, thereby suppressing adverse effects on the measurement object, such as discomfort.

[0074] The near-infrared light emitting device 10 of this embodiment is not limited to the configuration including the optical member shown in Fig. 3(a), and any configuration can be applied as long as it emits output light with the above-mentioned characteristic spectral distribution. Furthermore, the spectral distribution of the output light emitted from the near-infrared light emitting device 10 of this embodiment is not limited to the spectral distribution shown in Fig. 4.

[0075] [Biological Information Detection Device] Next, a biological information detection device according to this embodiment will be described. The biological information detection device according to this embodiment includes the near-infrared light emitting device 10 described above. FIG. 5 schematically shows an example of the biological information detection device according to this embodiment. The biological information detection device 20 includes at least a power supply circuit 21, a conductor 22, and the near-infrared light emitting device 10. The power supply circuit 21 supplies power to the solid-state light emitting element 1 in the near-infrared light emitting device 10 through the conductor 22.

[0076] As described above, the near-infrared light emitting device 10 converts electrical energy into light energy. The near-infrared light emitting device 10 converts at least a portion of the electrical energy supplied from the power supply circuit 21 into light energy that becomes output light 23 and outputs the converted light. The near-infrared light emitting device 10 in Fig. 5 is configured to emit output light 23 that includes at least near-infrared light. The near-infrared light emitting device 10 may also be configured to emit output light 23 that includes red light and near-infrared light.

[0077] The biological information detection device 20 of Fig. 5 further includes a first detector 27A and a second detector 27B. The first detector 27A detects a transmitted light component 25 of output light 23 emitted from the near-infrared light emitting device 10 and irradiated onto the irradiated body 24. Specifically, the first detector 27A detects near-infrared light in the transmitted light component 25 that has passed through the irradiated body 24. The second detector 27B detects a reflected light component 26 of the output light 23 emitted from the near-infrared light emitting device 10 and irradiated onto the irradiated body 24. Specifically, the second detector 27B detects near-infrared light in the reflected light component 26 that has reflected from the irradiated body 24. Note that the first detector 27A and the second detector 27B may detect red light in addition to near-infrared light.

[0078] In the biological information detection device 20 configured as described above, an irradiated object 24, which is the measurement target, is irradiated with output light 23 containing near-infrared light, and a transmitted light component 25 that has passed through the irradiated object 24 and a reflected light component 26 that has been reflected by the irradiated object 24 are detected by a first detector 27A and a second detector 27B. Therefore, the biological information detection device 20 can detect characteristic information of the irradiated object 24 that involves near-infrared light components.

[0079] The near-infrared light emitting device 10 of this embodiment can emit output light 23 that includes at least near-infrared light and is suitable for a detector. Therefore, by combining the light emitting device with a near-infrared detector, a biological information detection device suitable for industrial applications can be obtained.

[0080] Various types of photodetectors can be used for the first detector 27A and the second detector 27B. Specifically, depending on the usage form of the biological information detection device, quantum-type photodetectors (such as photodiodes, phototransistors, photo ICs, CCD image sensors, and CMOS image sensors) that detect electric charges generated when light is incident on a semiconductor PN junction can be used. Furthermore, thermal-type photodetectors (such as thermopiles that utilize the thermoelectric effect and pyroelectric elements that utilize the pyroelectric effect) that detect changes in electrical properties caused by a temperature rise due to heat generated when light is received, or infrared films that are sensitive to light can also be used as photodetectors.

[0081] The first detector 27A and the second detector 27B may be a single element using a single photoelectric conversion element, or an imaging element in which photoelectric conversion elements are integrated. The imaging element may be a linear type arranged one-dimensionally, or a surface type arranged two-dimensionally. Imaging cameras may also be used as the first detector 27A and the second detector 27B.

[0082] Although the biometric information detection device 20 in Figure 5 is equipped with both the first detector 27A and the second detector 27B, it is sufficient for the biometric information detection device to be equipped with at least one of the first detector 27A and the second detector 27B.

[0083] The biological information detection device of this embodiment can be used for medical purposes, animal medical purposes, and biotechnology. The biological information detection device of this embodiment can also be used for humans, animals, and plants, and can also be used for gases, liquids, and solids.

[0084] Furthermore, the biological information detection device of this embodiment is preferably used as a medical device, a treatment device, a beauty device, a health device, a care-related device, an analysis device, a measurement device, or an evaluation device.

[0085] For example, for the purpose of medical care or biotechnology development, the biological information detection device of this embodiment can be used for the inspection, detection, measurement, evaluation, analysis, observation, monitoring, separation, diagnosis, treatment, purification, etc. of 1) blood, body fluids, and their components, 2) excrement (urine and feces), 3) proteins and amino acids, 4) cells (including cancer cells), 5) genes, chromosomes, and nucleic acids, 6) biological samples, bacteria, specimens, and antibodies, 7) biological tissues, organs, and blood vessels, and 8) skin diseases and alopecia.

[0086] Furthermore, for example, for purposes of beauty and healthcare, the bioinformation detection device of this embodiment can be used for the examination, detection, measurement, evaluation, analysis, observation, monitoring, beautification, hygiene, growth promotion, health enhancement, diagnosis, etc. of 1) skin, 2) hair and body hair, 3) inside the mouth, teeth, and periodontium, 4) ears and nose, and 5) vital signs.

[0087] For example, for the purpose of nursing care, the biological information detection device of this embodiment can be used to check excretion, identify, manage, and monitor health conditions, and the like.

[0088] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0089] (Technology 1) A near-infrared light emitting device having a solid-state light emitting element and a wavelength converter including a phosphor, and emitting two or more fluorescent components from one light output surface, wherein the two or more fluorescent components include a first fluorescent component and a second fluorescent component arranged in order from the shortest wavelength side, and the first fluorescent component and the second fluorescent component are fluorescence based on electronic energy transition of a transition metal ion, the spectral shape of the first fluorescent component has a steeper slope from the fluorescence peak of the first fluorescent component to a long wavelength region than the slope of the short wavelength region, and the spectral shape of the second fluorescent component has a steeper slope from the fluorescence peak of the second fluorescent component to a short wavelength region than the slope of the long wavelength region, the emission intensity of the first fluorescent component at the long wavelength end is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the emission intensity of the second fluorescent component at the short wavelength end is 10% of the maximum emission intensity, The second fluorescent component has a fluorescent peak within a wavelength range of 780 nm or more and 1000 nm or less.

[0090] This configuration ensures a consistent balance of measurement light intensities at any location on the measurement object. Furthermore, while the target substance can be accurately quantified using the two-wavelength method, the fluorescent component between the first and second fluorescent components is significantly reduced, thereby minimizing adverse effects on the measurement object, such as discomfort.

[0091] (Technology 2) A near-infrared light emitting device that has a solid-state light emitting element and a wavelength converter containing a phosphor, and that emits two or more fluorescent components from one light output surface, further comprising a notch filter that controls wavelength-converted light converted by the wavelength converter, wherein the fluorescent components have a first fluorescent component on the short wavelength side and a second fluorescent component on the long wavelength side across a blocking region controlled by the notch filter, the first fluorescent component and the second fluorescent component being fluorescence based on electronic energy transition of a transition metal ion, and the second fluorescent component having a fluorescent peak within a wavelength range of 780 nm or more and 1000 nm or less.

[0092] This configuration ensures a consistent balance of measurement light intensities at any location on the measurement object. Furthermore, while the target substance can be accurately quantified using the two-wavelength method, the fluorescent component between the first and second fluorescent components is significantly reduced, thereby minimizing adverse effects on the measurement object, such as discomfort.

[0093] (Technology 3) The near-infrared light-emitting device according to Technology 1 or 2, wherein, in the spectral shape of the first fluorescent component, the maximum value of the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component is 8% / nm or more when the maximum emission intensity is taken as 100%, and the maximum value of the slope of the short-wavelength region from the fluorescence peak of the first fluorescent component is less than 8% / nm when the maximum emission intensity is taken as 100%; and, in the spectral shape of the second fluorescent component, the maximum value of the slope of the short-wavelength region from the fluorescence peak of the second fluorescent component is 8% / nm or more when the maximum emission intensity is taken as 100%, and the maximum value of the slope of the long-wavelength region from the fluorescence peak of the second fluorescent component is less than 8% / nm when the maximum emission intensity is taken as 100%.

[0094] This configuration cuts out the fluorescent components between the first fluorescent component and the second fluorescent component while increasing the intensities of the two measurement lights, thereby improving the measurement accuracy of the target substance while suppressing adverse effects on the measurement target.

[0095] (Technology 4) The near-infrared light-emitting device according to any one of technologies 1 to 3, wherein the first fluorescent component and the second fluorescent component are fluorescence based on an electronic energy transition of the same transition metal ion, and are fluorescence due to a dd transition or an fd transition.

[0096] With this configuration, the near-infrared fluorescence emitted from the wavelength converter has a broad spectral distribution with a large half-width, making it easy to obtain first and second fluorescent components with characteristic spectral distributions.

[0097] (Technology 5) The near-infrared light-emitting device according to any one of Technologies 1 to 4, wherein a wavelength difference between the long wavelength end wavelength of the first fluorescent component and the short wavelength end wavelength of the second fluorescent component is 20 nm or more and 100 nm or less.

[0098] With this configuration, the first fluorescent component and the second fluorescent component are clearly separated, and the accuracy of measuring the target substance by the two-wavelength method can be further improved.

[0099] (Technology 6) A near-infrared light emitting device according to any one of technologies 1 to 5, wherein the two or more fluorescent components are emitted from the same phosphor.

[0100] This configuration makes it easier to obtain fluorescence with a characteristic spectral distribution that includes the first fluorescent component and the second fluorescent component, and therefore can be suitably used in the two-wavelength method.

[0101] (Technology 7) A near-infrared light emitting device according to any one of technologies 1 to 6, wherein the first fluorescent component includes a light component in a wavelength range of 600 nm or more and less than 900 nm.

[0102] With this configuration, the measurement light on the short wavelength side can be at least one of red light and near-infrared light.

[0103] (Technology 8) The transition metal ion is Cr ３＋ , Cr ４＋ , Fe ３＋ and Eu ２＋ The near-infrared light emitting device according to any one of techniques 1 to 7, wherein the near-infrared light emitting device is at least one selected from the group consisting of:

[0104] This configuration makes it easier to obtain fluorescence with a characteristic spectral distribution that includes the first fluorescent component and the second fluorescent component, and therefore can be suitably used in the two-wavelength method.

[0105] (Technology 9) A biological information detection device comprising the near-infrared light emitting device according to any one of technologies 1 to 8.

[0106] With this configuration, it is possible to obtain a biological information detection device that can accurately acquire biological information by the two-wavelength method.

[0107] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to these examples.

[0108] [Fabrication of Light-Emitting Device] First, fluorescent ceramics were synthesized using a preparation method based on a solid-state reaction. ０．６９ , Sc ０．３ , Cr ０．０１ ) ２ O ３ We synthesized a fluorescent ceramic with the composition formula: ３ (Ga ０．９７ , Cr ０．０３ ) ２ Ga ３ O １２ We synthesized a fluorescent ceramic with the following composition formula:

[0109] The following compound powders were used as the main raw materials for synthesizing each fluorescent ceramic: Gallium oxide (Ga ２ O ３ ): Purity 4N, manufactured by Asia Materials Co., Ltd. Scandium oxide (Sc ２ O ３ Chromium oxide (Cr): Purity 3N, manufactured by High Purity Chemical Laboratory Co., Ltd. ２ O ３ ): Purity 3N, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd. Boric acid (H ３ BO ３ ): Purity 2N, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Gadolinium oxide (Gd ２ O ３ ): Purity 4N, manufactured by Japan Yttrium Co., Ltd.

[0110] First, the raw materials for the fluorescent ceramics were weighed out under the formulation conditions shown in Table 1. Next, the weighed raw materials were placed in the pot of a planetary ball mill, and water and φ3 mm alumina balls were added. The raw materials were then wet-mixed using the planetary ball mill. The resulting mixed slurry was then thoroughly dried in a thermostatic chamber at 125°C, and then lightly crushed using a mortar and pestle to obtain a raw material mixed powder.

[0111] Next, 1 g of the resulting raw material mixed powder for each example was filled into a mold (Φ13 mm), and then pressed at a pressure of 10 MPa using a hand press to produce a molded body. Each molded body was then fired under the firing conditions shown in Table 2 to obtain a sintered body.

[0112] Each sintered body was ground to a thickness of 100 μm using an automatic grinder (product number: DAG810, manufactured by Disco Corporation), to obtain each fluorescent ceramic. Finally, each fluorescent ceramic was processed to a size of 3.2 mm × 2.6 mm using an automatic dicing saw (product number: DAD3350, manufactured by Disco Corporation).

[0113]

[0114]

[0115] Next, a commercially available blue LED was prepared. The blue LED used was LEB P2MQ, product code LEB P2MQ-GSHQ-23-0, manufactured by amsOSRAM. The fluorescent ceramic was laminated and mounted on the blue LED to obtain a light-emitting module.

[0116] Next, a notch filter, which is an optical component, was prepared. An OD4.0 notch filter, product code #86-703, manufactured by Edmund Optics, was used as the notch filter. The central wavelength of the blocking region of this notch filter was 830 nm, and the half-width was 42 nm. The reflectance of the blocking region was 99% or higher. The transmission band of this notch filter outside the blocking region was 625 to 1100 nm, and the transmittance was 90% or higher.

[0117] Then, this notch filter was placed on a light-emitting module to obtain the light-emitting device of this example.

[0118] [Evaluation of Spectral Distribution] The operation of the light emitting device of the example obtained as described above was confirmed. Specifically, when power (11.37 V, 500 mA) was applied to the blue LED chip of the light emitting device, blue light was emitted from the blue LED chip as primary light. A part of this light was emitted from the Cr contained in the fluorescent ceramic. ３＋ is absorbed by Cr ３＋ The electron energy transition of the fluorine-containing compound converted the wavelength of the light into light containing near-infrared rays.

[0119] The wavelength-converted light was then transmitted through the notch filter, cutting off light with a wavelength around 830 nm and outputting the remaining light. The spectral distribution of the light output from the light-emitting device of this example is shown in FIG.

[0120] In the spectral distribution shown in Fig. 4, the first fluorescent component has a fluorescence peak wavelength of 804 nm, and the second fluorescent component has a fluorescence peak wavelength of 857 nm. The short wavelength end of the first fluorescent component is a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 713 nm, and the long wavelength end of the first fluorescent component is a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 813 nm. The short wavelength end of the second fluorescent component is a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 847 nm, and the long wavelength end of the second fluorescent component is a wavelength that is 10% of the fluorescence peak intensity of the first fluorescent component, i.e., a wavelength of 1011 nm.

[0121] The maximum value of the slope of the long-wavelength region from the fluorescence peak of the first fluorescent component was 25.86% / nm, when the maximum emission intensity of the fluorescence peak of the first fluorescent component was taken as 100%, and the maximum value of the slope of the short-wavelength region from the fluorescence peak of the first fluorescent component was 1.70% / nm, when the maximum emission intensity of the fluorescence peak of the first fluorescent component was taken as 100%.

[0122] Furthermore, the maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the short wavelength region was 13.00% / nm, when the maximum emission intensity of the first fluorescent component was taken as 100%. The maximum value of the slope of the region from the fluorescence peak of the second fluorescent component to the long wavelength region was 2.11% / nm, when the maximum emission intensity of the first fluorescent component was taken as 100%.

[0123] On the short wavelength side of the first fluorescent component, the wavelength range from the short wavelength end of the first fluorescent component to the fluorescence peak of the first fluorescent component was 91 nm, and further, on the long wavelength side of the first fluorescent component, the wavelength range from the fluorescence peak of the first fluorescent component to the long wavelength end of the first fluorescent component was 9 nm.

[0124] Furthermore, on the short wavelength side of the second fluorescent component, the wavelength range from the short wavelength end of the second fluorescent component to the fluorescence peak of the second fluorescent component was 10 nm, and on the long wavelength side of the second fluorescent component, the wavelength range from the fluorescence peak of the second fluorescent component to the long wavelength end of the second fluorescent component was 154 nm.

[0125] As described above, the output light emitted from the light-emitting device of the example had a steeper slope in the long-wavelength region from the fluorescence peak of the first fluorescent component than in the short-wavelength region, and a steeper slope in the short-wavelength region from the fluorescence peak of the second fluorescent component than in the long-wavelength region. Therefore, while the target substance can be accurately quantified by the two-wavelength method, the fluorescent component between the first fluorescent component and the second fluorescent component is significantly reduced, thereby suppressing adverse effects such as discomfort to the measurement subject.

[0126] 4, light with wavelengths of 930 nm or more is unnecessary light that is not used as measurement light, and therefore, light with wavelengths of 930 nm or more may be cut using, for example, a low-pass filter.

[0127] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

[0128] The entire contents of Japanese Patent Application No. 2023-119019 (filing date: July 21, 2023) are incorporated herein by reference.

[0129] According to the present disclosure, a near-infrared light emitting device can be provided that can suppress uneven illumination of light irradiated onto a measurement object, even when irradiating light of two different wavelengths.

[0130] REFERENCE SIGNS LIST 1 solid-state light-emitting element 2 wavelength converter 3 optical member (notch filter) 10 near-infrared light-emitting device

Claims

1. A near-infrared light-emitting device having a solid-state light-emitting element and a wavelength converter containing a phosphor, which emits two or more fluorescent components from a single light output surface, The two or more fluorescent components include a first fluorescent component and a second fluorescent component that are arranged in order from the short wavelength side, and the first fluorescent component and the second fluorescent component are fluorescence based on the electron energy transition of transition metal ions. The spectral shape of the first fluorescence component is such that the slope in the long-wavelength region from the fluorescence peak of the first fluorescence component is steeper than the slope in the short-wavelength region, and the spectral shape of the second fluorescence component is such that the slope in the short-wavelength region from the fluorescence peak of the second fluorescence component is steeper than the slope in the long-wavelength region. The emission intensity at the long wavelength end of the first fluorescent component is 10% of the maximum emission intensity at the fluorescence peak of the first fluorescent component and the fluorescence peak of the second fluorescent component, and the emission intensity at the short wavelength end of the second fluorescent component is 10% of the maximum emission intensity. The second fluorescent component is a near-infrared light-emitting device having the fluorescence peak within a wavelength range of 780 nm to 1000 nm.

2. A near-infrared light-emitting device having a solid-state light-emitting element and a wavelength converter containing a phosphor, which emits two or more fluorescent components from a single light output surface, The system further includes a notch filter for controlling the wavelength-converted light converted by the wavelength converter, The fluorescence component has a first fluorescence component on the short wavelength side and a second fluorescence component on the long wavelength side, separated by a blocking region controlled by the notch filter, and the first and second fluorescence components are fluorescence based on the electron energy transition of transition metal ions. The second fluorescent component is a near-infrared light-emitting device having a fluorescence peak in the wavelength range of 780 nm to 1000 nm.

3. In the spectral shape of the first fluorescence component, the maximum slope in the long-wavelength region from the fluorescence peak of the first fluorescence component is 8% / nm or more, when the maximum emission intensity at the fluorescence peaks of the first fluorescence component and the second fluorescence component is set to 100%, and the maximum slope in the short-wavelength region from the fluorescence peak of the first fluorescence component is less than 8% / nm, when the maximum emission intensity is set to 100%. The near-infrared light-emitting device according to claim 1 or 2, wherein, in the spectral shape of the second fluorescent component, the maximum slope in the short-wavelength region from the fluorescence peak of the second fluorescent component is 8% / nm or more when the maximum emission intensity is set to 100%, and the maximum slope in the long-wavelength region from the fluorescence peak of the second fluorescent component is less than 8% / nm when the maximum emission intensity is set to 100%.

4. The near-infrared light-emitting device according to claim 1 or 2, wherein the first fluorescent component and the second fluorescent component are fluorescence based on the electron energy transition of the same transition metal ion, and are fluorescence due to a d-d transition or an f-d transition.

5. The near-infrared light-emitting device according to claim 1, wherein the wavelength difference between the wavelength of the long-wavelength end of the first fluorescent component and the wavelength of the short-wavelength end of the second fluorescent component is 20 nm or more and 100 nm or less.

6. The near-infrared light-emitting device according to claim 1 or 2, wherein the two or more fluorescent components are emitted from the same phosphor.

7. The near-infrared light-emitting apparatus according to claim 1 or 2, wherein the first fluorescent component includes an optical component in the wavelength range of 600 nm or more and less than 900 nm.

8. The aforementioned transition metal ion is Cr ３＋ , Cr ４＋ Fe ３＋ and EU ２＋ The near-infrared light-emitting device according to claim 1 or 2, wherein it is at least one selected from the group consisting of the following.

9. A biological information detection device comprising a near-infrared light-emitting device according to claim 1 or 2.