Light emitting device and electronic apparatus using the same

Abstract

To provide a light emitting device that emits both near-infrared and visible light components simultaneously and achieves an increase in the output of the near-infrared light component and an increase in the area of a light output surface.SOLUTION: There is provided a light emitting device 10 in which a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A are combined, and which emits output light 4. The solid-state light emitting element emits primary light 3B. The first wavelength converter absorbs at least part of the primary light and converts this part into first wavelength-converted light 1B, and the second wavelength converter absorbs at least part of first mixed light 14 including first transmitted primary light 3BT1 that has passed through the first wavelength converter, and the first wavelength-converted light, and converts this part into second wavelength-converted light 2B. The output light includes at least transmitted first wavelength-converted light 1BT2 which is a light component obtained by the first wavelength-converted light having passed through the second wavelength converter, and a light component of the second wavelength-converted light. In the output light, the integral value of the energy intensity of a light component with a wavelength of less than 700 nm is larger than the integral value of the energy intensity of a light component with a wavelength of 700 nm or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light-emitting device and an electronic device using the same. [Background technology]

[0002] 2. Description of the Related Art Light emitting devices that are formed by combining at least a solid-state light emitting element and a phosphor and emit output light that contains a near-infrared light component have been known.

[0003] Patent Document 1 states that Cr 3+ and / or Ni 2+ The present invention discloses a light emitting device having a simple structure, which comprises a wavelength converter containing a phosphor having a luminescence center of 1000 nm and a semiconductor chip that emits excitation light. This light emitting device generates near-infrared light by converting the wavelength of blue or red light emitted by the semiconductor chip using the wavelength converter.

[0004] The light emitting device of Patent Document 1 mainly relates to an optoelectronic element that replaces conventional light sources, with an eye on applications in small and portable analytical devices and spectrometers, sensor applications in industrial machines, smartphones, endoscopes, etc. Known conventional light sources include halogen lamps, infrared lasers, and infrared LEDs. An example of Patent Document 1 discloses that the near-infrared light output of the light emitting device (optoelectronic element) is less than 50 mW.

[0005] Patent Document 2 discloses a light emitting device for industrial equipment used as a replacement for halogen lamps, for example. This light emitting device combines a light emitting element that emits light having a maximum intensity in the ultraviolet to blue wavelength region of 480 nm or less with a phosphor that contains at least a phosphor that converts light into near-infrared light, to obtain light containing near-infrared light components with a wide fluorescence spectrum half-width. An example of Patent Document 2 discloses that the output of near-infrared light from a light emitting device using an LED chip that emits 600 mW of ultraviolet light exceeds 10 mW. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6570653 [Patent Document 2] WO2019 / 240150 publication Summary of the Invention

[0007] Conventional light emitting devices, which are formed by combining at least a solid-state light emitting element and a phosphor and emit near-infrared and visible light components simultaneously, have had the problem that it is difficult to achieve both high output and a large area. This is because the primary light emitted by the solid-state light emitting element directly irradiates a wavelength converter that emits near-infrared light components, making it difficult to achieve a large area and high output, especially for the near-infrared light component.

[0008] Specifically, since the primary light emitted by a solid-state light-emitting element is usually directional, in the conventional light-emitting device, the directional primary light only locally irradiates the irradiated surface of the wavelength converter. Therefore, the area of ​​the irradiated surface irradiated with the strong primary light is reduced, and the intensity of the primary light irradiating the irradiated surface is likely to vary within the surface. The area irradiated with the strong light is likely to generate heat due to Stokes loss associated with the wavelength conversion of the phosphor contained in the wavelength converter. Since this heat induces temperature quenching of the phosphor, if the primary light has high directivity, it will lead to a local decrease in the wavelength conversion efficiency of the wavelength converter, and the average wavelength conversion efficiency will be easily reduced. In addition, the Stokes loss will be larger as the wavelength difference between the wavelength absorbed by the wavelength converter and the wavelength emitted by the fluorescent light is larger. Therefore, under the conditions where the primary light is the same, a phosphor that converts to near-infrared light is more likely to generate heat than a phosphor that converts to visible light, and will be more likely to induce a decrease in efficiency due to temperature quenching.

[0009] In addition, the primary light having high directivity is incident on the wavelength converter at an angle as it moves away from the central portion of the irradiated surface of the wavelength converter. Therefore, when the primary light having high directivity is used, the penetration depth of the primary light into the wavelength converter or the optical path length passing through the wavelength converter becomes long, and the color tone of the output light is likely to have a light distribution angle dependency that causes non-uniformity.

[0010] The present invention has been made to solve such problems. An object of the present invention is to provide a light-emitting device that emits both near-infrared and visible light components, is suitable for industrial applications that take into consideration how the light is seen by the human eye, and achieves both high output of the near-infrared light component and a large light output surface area, and an electronic device using the same.

[0011] Specifically, the present invention aims to provide a light-emitting device that is suitable for industrial applications, that emits both near-infrared and visible light components, and that achieves both a uniform high output of near-infrared light components and a large light output surface area. Another object of the present invention is to provide various electronic devices using the light-emitting device, such as inspection devices, detection devices, monitoring devices, sorting devices, analysis devices, measurement devices, and evaluation devices.

[0012] In order to solve the above-mentioned problems, a light emitting device according to an embodiment of the present invention is a light emitting device that includes a solid-state light emitting element, a first wavelength conversion body containing a first phosphor, and a second wavelength conversion body containing a second phosphor, and emits output light, wherein the solid-state light emitting element emits primary light, the first wavelength conversion body absorbs at least a part of the primary light and converts it into first wavelength-converted light having a fluorescent peak within a visible wavelength range of wavelengths equal to or greater than 380 nm and less than 780 nm, and the second wavelength conversion body converts at least a part of a first mixed light including a first transmitted primary light, which is the primary light that has passed through the first wavelength conversion body, and the first wavelength-converted light. portion and converts it into second wavelength-converted light having a fluorescent peak in a wavelength region exceeding 700 nm and having a near-infrared component in a wavelength region of 780 nm or more and less than 2500 nm, the first mixed light is light with a light color having a correlated color temperature of 2500 K or more and less than 40,000 K, the output light contains at least transmitted first wavelength-converted light which is a light component of the first wavelength-converted light that has been transmitted through the second wavelength converter, and a light component of the second wavelength-converted light, and the output light has an integral value of the energy intensity of the light component with a wavelength of less than 700 nm that is greater than the integral value of the energy intensity of the light component with a wavelength of 700 nm or more. A light emitting device according to an embodiment of the present invention is a light emitting device that includes a solid-state light emitting element, a first wavelength conversion body containing a first phosphor, and a second wavelength conversion body containing a second phosphor, and emits output light, wherein the solid-state light emitting element emits primary light, the first wavelength conversion body absorbs at least a portion of the primary light and converts it into first wavelength-converted light having a fluorescent peak within a visible wavelength range of wavelengths not less than 380 nm and less than 780 nm, and the second wavelength conversion body converts the first wavelength-converted light into first transmitted primary light, which is the primary light that has passed through the first wavelength conversion body, and and converts it into second wavelength-converted light having a fluorescent peak in a wavelength region exceeding 700 nm and having a near-infrared component in a wavelength region of 780 nm or more and less than 2500 nm, the first mixed light being light with a correlated color temperature of 2500 K or more and less than 40,000 K, the output light containing at least a transmitted first wavelength-converted light which is a light component of the first wavelength-converted light that has been transmitted through the second wavelength converter and a light component of the second wavelength-converted light, and the output light has a luminous flux of 291.6 lm or more.

[0013] An electronic device according to an aspect of the present invention includes the above-described light-emitting device. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a light emitting device according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a light emitting device according to the second embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of a light emitting device according to the third embodiment. [Figure 4] FIG. 4 shows an example of the spectral distribution of output light emitted by the light emitting device according to this embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of an electronic device according to the fourth embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of an electronic device according to the fifth embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of an electronic device according to the sixth embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of an electronic device according to the seventh embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of an electronic device according to the eighth embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of an electronic device according to the ninth embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of an electronic device according to the tenth embodiment. [Figure 12] FIG. 12 shows an example of the spectral distribution of output light emitted by the light emitting device according to the embodiment. [Figure 13] FIG. 13 shows an example of the spectral distribution of the output light emitted by the light emitting device according to the embodiment. [Figure 14] FIG. 14 shows an example of the spectral distribution of the output light emitted by the light emitting device according to the embodiment. [Figure 15] FIG. 15 shows an example of the spectral distribution of the output light emitted by the light emitting device according to the embodiment. [Figure 16] FIG. 16 shows an example of the spectral distribution of output light emitted by the light emitting device according to the embodiment. [Figure 17] FIG. 17 shows an example of the spectral distribution of the output light emitted by the light emitting device according to the embodiment. [Figure 18] FIG. 18 shows an example of the spectral distribution of output light emitted by the light emitting device according to the embodiment. [Figure 19] FIG. 19 shows an example of the spectral distribution of output light emitted by the light emitting device according to the embodiment. [Figure 20] FIG. 20 shows an example of the spectral distribution of the output light emitted by the light emitting device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a light-emitting device according to an embodiment and an electronic device using the light-emitting device will be described with reference to the drawings. Specifically, the electronic device will be described as an inspection device, a medical device, etc. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios.

[0016] <Light emitting device> (Outline of the configuration of the light-emitting device) First, the light emitting device will be described. Figures 1 to 3 are schematic diagrams showing the configuration of the light emitting device according to the first to third embodiments. Note that in the schematic diagrams of Figures 1 to 3, the power source and the like used in the light emitting device are omitted.

[0017] FIG. 1 is a schematic diagram showing the configuration of a light emitting device according to a first embodiment. The light emitting device 10A (10) according to the first embodiment shown in FIG. 1 includes a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A. Specifically, the light emitting device 10A according to the first embodiment is a light emitting device having a simple configuration that uses one each of the solid-state light emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A. The combined structure of the solid-state light emitting element 3 and the first wavelength converter 1A is also called a "light emission-wavelength conversion unit." The light emitting device 10A includes one light emission-wavelength conversion unit.

[0018] Fig. 2 is a schematic diagram showing the configuration of a light emitting device according to a second embodiment. The light emitting device 10B (10) according to the second embodiment shown in Fig. 2 includes a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A. Specifically, the light emitting device 10B according to the second embodiment is a light emitting device provided with a plurality of light emission-wavelength conversion units, which are combination structures of the solid-state light emitting element 3 and the first wavelength converter 1A.

[0019] FIG. 3 is a schematic diagram showing the configuration of a light emitting device according to a third embodiment. The light emitting device 10C (10) according to the third embodiment shown in FIG. 3 includes a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A. Specifically, the light emitting device 10C according to the third embodiment is an example of a light emitting device having a configuration using only a plurality of solid-state light emitting elements 3. In the light emitting device 10C, the plurality of solid-state light emitting elements 3 are aligned and arranged so that the distance between each solid-state light emitting element 3 and the first wavelength converter 1A is constant. In the light emitting device 10C, the plurality of solid-state light emitting elements 3 and the first wavelength converter 1A are spaced apart from each other.

[0020] [First embodiment] The light emitting device 10A according to the first embodiment will be described below.

[0021] The light emitting device 10A is a light emitting device that emits output light 4, and is formed by combining at least a solid-state light emitting element 3, a first wavelength converter 1A containing a first phosphor 1, and a second wavelength converter 2A containing a second phosphor 2.

[0022] In the light emitting device 10A, a first wavelength converter 1A is disposed between the solid-state light emitting element 3 and the second wavelength converter 2A. Therefore, in the light emitting device 10A, the primary light 3B emitted by the solid-state light emitting element 3 is irradiated to the second wavelength converter 2A after passing through the first wavelength converter 1A. That is, in the light emitting device 10A, the primary light 3B emitted by the solid-state light emitting element 3 is not irradiated to the second wavelength converter 2A without passing through the first wavelength converter 1A.

[0023] Hereinafter, "light obtained by transmitting the primary light 3B emitted by the solid-state light-emitting element 3 through the first wavelength converter 1A" is also referred to as "first transmitted primary light 3BT1". Here, "light transmitted through the first wavelength converter 1A" means "light obtained by transmitting the primary light 3B introduced from one end of the first wavelength converter 1A from the other end of the first wavelength converter 1A, regardless of reflection within the first wavelength converter 1A". For example, "light obtained by transmitting the primary light 3B introduced from one end of the first wavelength converter 1A without being reflected by the first phosphor 1 in the first wavelength converter 1A and then transmitting the light from the other end of the first wavelength converter 1A" is the first transmitted primary light 3BT1. In addition, "light obtained by transmitting the primary light 3B introduced from one end of the first wavelength converter 1A through the first phosphor 1 in the first wavelength converter 1A and then transmitting the light from the other end of the first wavelength converter 1A" is also the first transmitted primary light 3BT1. The first transmitted primary light 3BT1 has a spectral distribution derived from the primary light 3B, and has a lower light intensity than the primary light 3B.

[0024] The solid-state light-emitting element 3 emits primary light 3B. The first wavelength converter 1A absorbs at least a part of the primary light 3B and converts it into first wavelength-converted light 1B having a fluorescence peak within the visible wavelength range of not less than 380 nm and not more than 780 nm.

[0025] The second wavelength converter 2A absorbs at least a part of the first mixed light 14 containing the first transmitted primary light 3BT1 and the first wavelength-converted light 1B, and converts it into second wavelength-converted light 2B. The first mixed light 14 is light containing the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B.

[0026] The first mixed light 14 has a correlated color temperature of 2500 K or more and less than 40000 K, preferably 3800 K or more and less than 20000 K. The upper and lower limit values ​​of the correlated color temperature of the first mixed light 14 are not particularly limited as long as they are within the above-mentioned range, and the upper limit temperature can be appropriately selected from, for example, 5000 K, 7000 K, 10000 K, 15000 K, etc.

[0027] The second wavelength-converted light 2B has a fluorescence peak in a wavelength range exceeding 700 nm and a near-infrared component in a wavelength range of 780 nm or more and less than 2500 nm. The second wavelength-converted light 2B preferably has a fluorescence peak in a wavelength range exceeding 750 nm. The second wavelength-converted light 2B preferably has a near-infrared component in a wavelength range of 780 nm or more and less than 1000 nm.

[0028] The output light 4 contains at least the optical components of the first wavelength-converted light 1B and the second wavelength-converted light 2B.

[0029] In the light emitting device 10A, due to such a device configuration, the second wavelength converter 2A is not directly irradiated with the primary light 3B emitted by the solid-state light emitting element 3.

[0030] The first mixed light 14 irradiated to the second wavelength converter 2A includes a first transmitted primary light 3BT1 and a first wavelength-converted light 1B. Here, the first wavelength-converted light 1B is light having lower energy than the primary light 3B, which has been converted to light with a longer wavelength by the first wavelength converter 1A. The first transmitted primary light 3BT1 is light having a lower intensity than the primary light 3B, which has been weakened in intensity by the reduction in the number of photons due to the wavelength conversion in the first wavelength converter 1A, and which has been light-diffused by the first wavelength converter 1A. The spectral distribution of the first transmitted primary light 3BT1 is derived from the spectral distribution of the primary light 3B.

[0031] The second wavelength converter 2A is irradiated with the first mixed light 14, which is made up of scattered photons and has a relatively reduced intensity. Here, the first mixed light 14 usually has a larger irradiation area than the primary light 3B emitted by the solid-state light-emitting element 3. Therefore, in the second wavelength converter 2A, localized heat generation (due to Stokes loss) caused by the wavelength conversion of the incident light can be suppressed.

[0032] In the second wavelength converter 2A, the second phosphor 2 is not directly excited by the primary light 3B that causes a relatively large Stokes loss or the primary light 3B that has a large light energy density. Moreover, in the second wavelength converter 2A, the excitation of only a part of the second phosphor 2 in the second wavelength converter 2A, as in the case of excitation by the primary light 3B having directionality, is suppressed. Therefore, in the light emitting device 10A, photons are uniformly and homogeneously irradiated and absorbed over the entire second wavelength converter 2A, and the light output surface is easily enlarged. This makes it easy to enlarge the irradiated surface onto which the output light 4 is irradiated.

[0033] In the light emitting device 10A, photons are easily irradiated and absorbed uniformly throughout the second wavelength converter 2A, so that local temperature rise due to heat generation accompanying wavelength conversion of the second wavelength converter 2A can be suppressed. In addition, photons are easily irradiated and absorbed uniformly throughout the second wavelength converter 2A, so that the light output surface can be enlarged and the irradiated surface can be made large. Therefore, the light emitting device 10A becomes a light emitting device capable of outputting visible light and near infrared light, which is suitable for suppressing temperature quenching of the second phosphor 2 contained in the second wavelength converter 2A and for increasing the output of the near infrared light component and for making the light output surface large.

[0034] In the light emitting device 10A, the solid-state light emitting element 3 and the first wavelength converter 1A are separate bodies. However, as a modification of the light emitting device 10A, instead of the solid-state light emitting element 3 and the first wavelength converter 1A, an integrated wavelength conversion type light emitting element formed by combining the solid-state light emitting element 3 and the first wavelength converter 1A can be used. In other words, the solid-state light emitting element 3 and the first wavelength converter 1A can be combined to form a wavelength conversion type light emitting element.

[0035] Wavelength-converted light-emitting elements can be easily manufactured using white LED technology. Wavelength-converted light-emitting elements that emit light with a color having a correlated color temperature of 2500K or more and less than 40000K can also be easily manufactured using white LED technology. For example, wavelength-converted light-emitting elements that emit light with a color having a correlated color temperature of 2600K or more and less than 12000K are readily available on the market as white LEDs in a variety of specifications and configurations. For this reason, light-emitting devices that use wavelength-converted light-emitting elements can quickly respond to customer requests with fewer steps, from design to product development and industrial production.

[0036] Each component of the light emitting device 10A will be described in detail below.

[0037] (Solid-state light-emitting device 3) The solid-state light-emitting element 3 is a member that emits primary light 3B. For example, a solid-state light-emitting element such as a light-emitting diode or a laser diode can be used as the solid-state light-emitting element 3. Note that the solid-state light-emitting element 3 is not limited to these, and any solid-state light-emitting element can be used as long as it is capable of emitting primary light 3B.

[0038] For example, if an LED module emitting light with high wattage energy of 1W or more or a laser diode is used as the solid-state light-emitting element 3, a light-emitting device 10A that can be expected to output light containing near-infrared light components of several hundred mW class can be obtained. If an LED module emitting light with high wattage energy of 3W or more or 10W or more is used as the solid-state light-emitting element 3, a light-emitting device 10A that can be expected to output light of several W class can be obtained. If an LED module emitting light with high wattage energy of 30W or more is used, a light-emitting device 10A that can be expected to output light output exceeding 10W can be obtained. If an LED module emitting light with high wattage energy of 100W or more is used, a light-emitting device 10A that can be expected to output light output exceeding 30W can be obtained.

[0039] When a laser diode is used as the solid-state light-emitting element 3, the primary light 3B becomes laser light, and a high-density spot light is irradiated onto the first wavelength converter 1A. Therefore, the light-emitting device 10A using a laser diode as the solid-state light-emitting element 3 can be used as a high-output point light source, and the range of industrial applications of solid-state lighting can be expanded.

[0040] As a modification of the light emitting device 10A, a light guiding member such as an optical fiber can be provided between the solid-state light emitting element 3 and the first wavelength converter 1A. According to this modification, the solid-state light emitting element 3 and the first wavelength converter 1A are spatially separated, the light emitting section of the light emitting device is light and can be moved freely, and a light emitting device 10 can be obtained in which the irradiation location can be easily changed freely.

[0041] As the laser diode, for example, an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL) can be used.

[0042] The light energy density of the primary light 3B emitted by the solid-state light-emitting element 3 is 0.3 W / mm 2 It is preferable that the power consumption exceeds 1.0 W / mm 2 When the light energy density of the primary light 3B is within the above range, for example, even when a diffusion plate or the like (not shown) is disposed between the solid-state light-emitting element 3 and the first wavelength converter 1A as a modified example of the light-emitting device 10A, it is possible to obtain a light-emitting device that emits a relatively strong output light 4.

[0043] The upper limit of the light energy density of the primary light 3B emitted by the solid-state light-emitting element 3 is not particularly limited, but is, for example, 30 W / mm 2 It can be said that:

[0044] The light emitting device 10A preferably includes a plurality of solid-state light emitting elements 3. When the light emitting device 10A includes a plurality of solid-state light emitting elements 3, it is easy to increase the output of the primary light 3B, and thus a light emitting device suitable for achieving high output can be obtained. The number of solid-state light emitting elements 3 is not particularly limited. Depending on the application, the number can be appropriately selected from, for example, 2×2, 3×3, 5×5, 8×8, 10×10 elements with the same number vertically and horizontally, or 2×3, 3×5, 3×10 elements with an uneven number vertically and horizontally.

[0045] In the light emitting device 10A, if the solid-state light emitting element 3 is a surface-emitting light source of a surface-emitting type, this is preferable because it suppresses variations in intensity distribution and unevenness in color tone of the primary light 3B irradiated to the first wavelength converter 1A, and makes it possible to suppress unevenness in the intensity distribution of the output light, etc.

[0046] The solid-state light-emitting element 3 can be used in combination with multiple types of solid-state light-emitting elements. Furthermore, the solid-state light-emitting element 3 can be used in combination with multiple types of solid-state light-emitting elements emitting primary light 3B with different color tones. When multiple types of solid-state light-emitting elements emitting primary light 3B with different color tones are used in combination, the first wavelength converter 1A can absorb at least a part of the primary light 3B emitted by at least one type of solid-state light-emitting element 3 and convert it into first wavelength-converted light 1B.

[0047] (primary light) The primary light 3B is light emitted by the solid-state light-emitting element 3). The primary light 3B may be light of a wavelength that can be partially absorbed by the first wavelength converter 1A and converted into first wavelength-converted light 1B having a fluorescence peak within the visible wavelength range of 380 nm or more and less than 780 nm. The primary light 3B may be light having a maximum intensity within the wavelength range of ultraviolet light or visible light. The wavelength range of ultraviolet light or visible light may be, for example, a wavelength range of 350 nm or more and less than 750 nm.

[0048] As the primary light 3B, for example, long-wavelength ultraviolet light of 315 nm or more and less than 400 nm (UV-A) is used. As the primary light 3B, for example, violet light or blue light of 380 nm or more and less than 495 nm is used. As the primary light 3B, for example, green light or yellow light of 495 nm or more and less than 590 nm is used. As the primary light 3B, for example, orange light or red light of 590 nm or more and less than 750 nm is used.

[0049] The primary light 3B is preferably light having a maximum intensity within a wavelength range of 435 nm or more and less than 560 nm, more preferably within a wavelength range of 440 nm or more and less than 480 nm. If such light is used as the primary light 3B, an orthodox blue LED or a white LED with a blue LED specification can be used, which facilitates speedy product development and industrial production of the light emitting device 10A.

[0050] In addition, the primary light 3B is preferable because when the photons constituting the primary light are supplied from a plurality of solid-state light-emitting elements, a large number of photons can be supplied to the first wavelength converter 1A in proportion to the number of solid-state light-emitting elements 3, thereby making it possible to increase the power of the output light 4.

[0051] (First wavelength converter 1A) The first wavelength converter 1A is a member containing the first phosphor 1.

[0052] As the first wavelength converter 1A, for example, a wavelength converter in which the first phosphor 1 is sealed with a resin such as silicone, an all-inorganic wavelength converter in which the first phosphor 1 is sealed with a low-melting point glass, an all-inorganic wavelength converter in which the first phosphor 1 is bound with a binder, etc. are used. In addition, as the first wavelength converter 1A, for example, a wavelength converter made of a sintered body of an inorganic material obtained by sintering the first phosphor 1, etc. are used. As a wavelength converter made of a sintered body of an inorganic material, for example, a wavelength converter made of fluorescent ceramics is used.

[0053] The first wavelength converter 1A may be a wavelength converter having a composite form as appropriate, and may be used, for example, as a wavelength converter having a structure in which the above-mentioned wavelength converters are stacked.

[0054] Resin-encapsulated wavelength converters can be manufactured relatively easily using powdered phosphors, which is advantageous in providing relatively inexpensive light-emitting devices. On the other hand, all-inorganic wavelength converters have excellent thermal conductivity and can be easily designed for heat dissipation, so that it is possible to suppress the temperature rise of the wavelength converter and suppress the thermal quenching of the phosphor, thereby achieving high wattage output.

[0055] The thickness etc. of the first wavelength converter 1A is not particularly limited, but as an example, the maximum thickness is 100 μm or more and less than 5 mm, preferably 200 μm or more and less than 1 mm.

[0056] The first wavelength converter 1A is preferably arranged so as to cover the entire light output surface of the solid-state light-emitting element 3, and more preferably arranged so as to cover the entire light output surface of the surface-emitting light source. When the first wavelength converter 1A is arranged in this manner, the primary light 3B efficiently irradiates the first wavelength converter 1A, thereby obtaining a highly efficient light-emitting device 10A having a high conversion efficiency of the primary light 3B to the first wavelength-converted light 1B.

[0057] The first wavelength converter 1A can be made translucent. When the first wavelength converter 1A is translucent, the light components generated by wavelength conversion inside the wavelength converter can be emitted through the first wavelength converter 1A. Therefore, when the first wavelength converter 1A is translucent, a light emitting device 10A suitable for outputting light components can be obtained.

[0058] (First phosphor 1) The first phosphor 1 is included in the first wavelength converter 1A. The first phosphor 1 absorbs at least a part of the primary light 3B emitted by the solid-state light emitting element 3 and converts it into first wavelength-converted light 1B. As the first phosphor 1, for example, various inorganic phosphors known for use as solid-state lighting light sources, etc. (hereinafter, "inorganic phosphor" will be referred to simply as "phosphor") can be used.

[0059] Light emitting device 10A using a phosphor that emits wavelength-converted blue light with a maximum fluorescence intensity in the wavelength range of 435 nm or more and less than 500 nm as first phosphor 1 produces output light 4 containing a blue light component. Light emitting device 10A using a phosphor that emits wavelength-converted blue-green or green light with a maximum fluorescence intensity in the wavelength range of 470 nm or more and less than 530 nm as first phosphor 1 produces output light 4 containing a blue-green light component.

[0060] Light emitting device 10A using a phosphor that emits wavelength-converted green or yellow-green light with a maximum fluorescence intensity in the wavelength range of 500 nm or more and less than 560 nm as first phosphor 1 produces output light 4 that includes a green light component. Light emitting device 10A using a phosphor that emits wavelength-converted yellow or orange light with a maximum fluorescence intensity in the wavelength range of 560 nm or more and less than 600 nm as first phosphor 1 produces output light 4 that includes a yellow light component.

[0061] According to the light emitting device 10A using as the first phosphor 1 a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a red or deep red wavelength range of 600 nm or more and less than 700 nm, preferably 610 nm or more and less than 660 nm, output light 4 containing a red light component is obtained.

[0062] These light emitting devices 10A can be constructed by using a solid-state light emitting element 3 that emits primary light 3B that exhibits an intensity maximum within a wavelength range less than the wavelength at which the first phosphor 1 exhibits a fluorescent intensity maximum.

[0063] In addition, when the light emitting device 10A uses a phosphor that emits wavelength-converted light containing a blue-green light component that has high luminosity in scotopic vision, it is possible to obtain a light emitting device 10A that emits output light 4 that is easily visible in darkness or darkness. When the light emitting device 10A uses a phosphor that emits wavelength-converted light containing a green light component that has high luminosity in photopic vision, it is possible to obtain a light emitting device 10A that emits output light 4 that is easily visible in bright places.

[0064] When a phosphor that emits wavelength-converted light containing a yellow light component is used as the first phosphor 1, a light emitting device 10A suitable for improving the efficiency of output light of a light emitting device used in a work environment that uses a resin that is easily photosensitive to ultraviolet light or blue light can be obtained. When a phosphor that emits wavelength-converted light containing a red light component is used as the first phosphor 1, a light emitting device 10A suitable for lighting design that improves the appearance of reddish foods such as meat, tuna, and apples, and human skin that has a flesh color can be obtained.

[0065] As the first phosphor 1, for example, a phosphor activated with rare earth ions, transition metal ions, etc. and emitting visible fluorescence can be used. Specifically, as the first phosphor 1, oxides, sulfides, nitrides, halides, oxysulfides, oxynitrides, oxyhalides, etc. containing rare earth ions, transition metal ions, etc. as fluorescent ions (luminescence centers) can be used. As the rare earth ions, for example, Ce 3+ and Eu 2+ At least one of the following is used. As the transition metal ion, for example, Mn 4+ is used.

[0066] More specifically, halophosphates, phosphates, halosilicates, silicates, aluminates, aluminosilicates, borates, germanates, nitrosilicates, aluminosilicates, oxynitrides, aluminosilicates, etc. may be used as the first phosphor 1. As the first phosphor 1, a material suitable for the lighting design may be appropriately selected from the above substances.

[0067] From the viewpoint of suppressing the Stokes loss of absorbed light accompanying the wavelength conversion by the second wavelength converter 2 A, the first wavelength converter 1A preferably contains a first phosphor 1 that emits wavelength-converted light that exhibits a maximum fluorescence intensity within as long a wavelength range as possible. In this case, the first wavelength converter preferably contains a red phosphor that emits light having a fluorescence peak in the red wavelength range of 600 nm or more and less than 660 nm.

[0068] With this configuration, the second phosphor 2 contained in the second wavelength converter 2A can be excited by using red light whose wavelength is close to the wavelength region of the near-infrared light emitted by the first wavelength converter 1A. According to the light emitting device 10A in which the first wavelength converter includes the above-mentioned red phosphor, the Stokes loss accompanying the wavelength conversion of the second wavelength converter 2A can be further reduced, heat generation accompanying the wavelength conversion can be suppressed, and temperature quenching of the second phosphor 2 can be suppressed. Therefore, according to the light emitting device 10A in which the first wavelength converter includes the above-mentioned red phosphor, it is possible to further increase the output of near-infrared light.

[0069] The red phosphor is preferably Eu2+ Composite nitride phosphor or composite oxynitride phosphor activated with Eu 2+ The phosphor is called "activated nitride phosphor." 2+ As the activated nitride phosphor, for example, phosphors of alkaline earth metal nitride silicate, alkaline earth metal nitride aluminosilicate, alkaline earth metal oxynitride silicate, and alkaline earth metal oxynitride aluminosilicate are used. 2+ Specifically, the activated nitride phosphor is MAlSiN3:Eu 2+ , MAlSi4N7:Eu 2+ , M2Si5N8:Eu 2+ (wherein M is at least one element selected from Ca, Sr, and Ba) is used as the main component of the red phosphor. 2+ The activated nitride phosphor is MAlSiN3:Eu 2+ , MAlSi4N7:Eu 2+ , M2Si5N8:Eu 2+ Si 4+ -N 3+ Some of the combinations of Al 3+ -O 2― Eu in modified compositions substituted with 2+ Activated nitride phosphors and the like are used.

[0070] The EU 2+ Many activated nitride phosphors have the property of absorbing light components over a wide wavelength range from blue to green to yellow to orange and converting them into red light, so solid-state light-emitting elements that emit not only blue light but also green light or yellow light can be used as the solid-state light-emitting element 3. According to the light-emitting device 10A using such solid-state light-emitting elements, it is easy to achieve a form that reduces the Stokes loss during final wavelength conversion to near-infrared light, and it is possible to increase the efficiency of the output light 4.

[0071] When a solid-state light-emitting element that emits blue light is used as the solid-state light-emitting element, a light-emitting device 10A is obtained that is suitable for obtaining output light 4 with high color rendering properties that contains at least two types of light components, blue and red, that constitute the three primary colors of light (blue, green, and red).

[0072] From the viewpoint of suppressing fluorescent output saturation of the first wavelength converter 1A and supplying more photons to the second wavelength converter 2A, it is preferable that the first wavelength converter 1A contains a first phosphor 1 having as short an afterglow property as possible.

[0073] When using a first phosphor 1 having a short decay time, the first phosphor 1 is Ce. 3+ It is preferred to use only phosphors activated with .

[0074] Ce 3+ Since Ce exhibits light absorption and fluorescence emission based on parity-allowed spin-allowed electronic energy transition, light absorption and fluorescence emission occur instantaneously. Therefore, the fluorescence output is unlikely to saturate even under irradiation conditions of high-density excitation light such as laser light. Here, the fluorescence output saturation refers to the phenomenon in which the fluorescence output saturates with an increase in the intensity of the excitation light energy. For this reason, the use of Ce as the first phosphor 1 is 3+ If only a phosphor activated with Ce is used, the number of photons of the primary light 3B directly irradiated on the first wavelength converter 1A can be increased to increase the intensity, and it becomes easy to increase the number of photons supplied from the solid-state light emitting element 3. 3+ According to light emitting device 10A using only phosphors activated with , it becomes easy to increase the number of output photons, and high output of near infrared light and visible light is possible.

[0075] Ce 3+ Examples of phosphors activated with Ce include Ce, which has a garnet-type crystal structure. 3+ A composite oxide phosphor activated with Ce (hereinafter, this phosphor is called "Ce 3+ The Ce activated garnet phosphor is used. 3+ Specifically, a rare earth aluminum garnet phosphor is used as the phosphor activated with Lu3Al2(AlO4)3:Ce 3+ , Y3Al2(AlO4)3:Ce 3+ , Lu3Ga2(AlO4)3:Ce 3+ , Y3Ga2(AlO4)3:Ce 3+Garnet compounds, etc., which are solid solutions formed from these compounds as end members, are used.

[0076] Ce 3+ Many activated garnet phosphors have the property of absorbing blue light and converting it to green light. 3+ When an activated garnet phosphor is used, it is easy to use a solid-state light-emitting element 3 that emits blue light as the solid-state light-emitting element 3 that emits the primary light 3B. 3+ By using an activated garnet phosphor, it becomes easy to obtain output light 4 with high color rendering properties that contains at least two types of light components, blue and green, which constitute the three primary colors of light (blue, green, red).

[0077] In addition, with the advancement of in-vehicle headlamp technology and high-power projector technology, Ce, which is suitable for high output and reliability, has been used in recent years. 3+ The technology for making activated garnet phosphors into ceramics has been progressing. 3+ When using activated garnet phosphors, Ce is preferred in terms of high output and reliability. 3+ It is relatively easy to provide the light emitting device 10A including the first wavelength converter 1A made of fluorescent ceramics of an activated garnet phosphor.

[0078] Nowadays, LEDs that emit blue light and Ce that emit yellow-green light are widely used. 3+ A wide variety of white LED light sources that combine an activated garnet phosphor are available on the market, and are manufactured and sold by many companies. Therefore, white LED light sources and related technologies are easily available, and the light emitting device 10A that uses a white LED light source as the light emission-wavelength conversion unit can be developed quickly and with little effort.

[0079] (First wavelength converted light 1B) In the light emitting device 10A, the first wavelength converter 1A absorbs at least a part of the primary light 3B and converts it into first wavelength converted light 1B having a fluorescence peak within the visible wavelength range of not less than 380 nm and not more than 780 nm.

[0080] The first wavelength-converted light 1B is, for example, a visible light component having an intensity maximum value within a wavelength range of 435 nm or more and less than 700 nm. The first wavelength-converted light 1B is also, for example, a light component having an intensity maximum value within a wavelength range of 500 nm or more and less than 600 nm, preferably 510 nm or more and less than 560 nm. The first wavelength-converted light 1B is also, for example, a light component having an intensity maximum value within a wavelength range of 600 nm or more and less than 660 nm, preferably 610 nm or more and less than 650 nm. In the light emitting device 10A, the first wavelength-converted light 1B can be at least one of the above light components.

[0081] (Second wavelength converter 2A) The second wavelength converter 2A is a member containing the second phosphor 2.

[0082] The second wavelength converter 2A is a member that absorbs at least a part of the first mixed light 14 and converts it into second wavelength-converted light 2B that has a fluorescence peak in a wavelength region exceeding 700 nm and has a near-infrared component in a wavelength region of 780 nm or more and less than 2500 nm. The first mixed light 14 is light that contains the first transmitted primary light 3BT1, which is the primary light 3B that has transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B.

[0083] As the second wavelength converter 2A, for example, a wavelength converter in which the second phosphor 2 is sealed with a resin such as silicone, an all-inorganic wavelength converter in which the second phosphor 2 is sealed with a low-melting point glass, an all-inorganic wavelength converter in which the second phosphor 2 is bound with a binder, etc. are used. In addition, as the second wavelength converter 2A, for example, a wavelength converter made of a sintered body of an inorganic material obtained by sintering the second phosphor 2 is used. As a wavelength converter made of a sintered body of an inorganic material, for example, a wavelength converter made of fluorescent ceramics is used.

[0084] The second wavelength converter 2A is similar to the first wavelength converter 1A, except that the second wavelength converter 2A uses a second phosphor 2 instead of the first phosphor 1. For example, the form of the second wavelength converter 2A is similar to the form of the first wavelength converter 1A. Therefore, a description of the form of the second wavelength converter 2A will be omitted or simplified.

[0085] The second wavelength converter 2A is preferably arranged so as to cover the entire first wavelength converter 1A. When the second wavelength converter 2A is arranged in this manner, the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first converted wavelength light 1B emitted from the first wavelength converter 1A efficiently irradiate the second wavelength converter 2A. Therefore, when the second wavelength converter 2A is arranged in this manner, a highly efficient light emitting device 10A is obtained in which the conversion efficiency of the first transmitted primary light 3BT1 and the first converted wavelength light 1B to the second converted wavelength light 2B is high.

[0086] The second wavelength converter 2A can be made translucent. When the second wavelength converter 2A is translucent, not only the first transmitted primary light 3BT1 and the first converted wavelength light 1B but also the light components generated by wavelength conversion inside the wavelength converter can be transmitted through the second wavelength converter 2A and emitted. Therefore, when the second wavelength converter 2A is translucent, a light emitting device 10A suitable for outputting these light components can be obtained.

[0087] The second wavelength converter 2A can have a property of transmitting at least the second converted wavelength light 2B. With this configuration, the second wavelength converter 2A transmits the near-infrared light component of the second converted wavelength light 2B, thereby suppressing the loss of the near-infrared light component due to absorption of photons by the wavelength converter itself inside the wavelength converter. Therefore, when the second wavelength converter 2A has a property of transmitting at least the second converted wavelength light 2B, a light emitting device 10A suitable for achieving high output of near-infrared light can be obtained.

[0088] (Second phosphor 2) The second phosphor 2 is included in the second wavelength converter 2A. The second phosphor 2 is a phosphor that absorbs at least a part of the first mixed light 14 including the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B, and converts it into second wavelength-converted light 2B.

[0089] The first transmitted primary light 3BT1 is light whose intensity is weakened by a decrease in the number of photons due to wavelength conversion in the first wavelength converter 1A and which is further optically diffused by the first wavelength converter 1A, and has a lower intensity than the primary light 3B. The spectral distribution of the first transmitted primary light 3BT1 is derived from the spectral distribution of the primary light 3B.

[0090] For this reason, even if the first transmitted primary light 3BT1 contained in the first mixed light 14 is replaced with primary light 3B, the second phosphor 2 absorbs at least a portion of the mixed light containing primary light 3B and first wavelength-converted light 1B and converts it to second wavelength-converted light 2B. As the second phosphor 2, for example, various inorganic phosphors known for use in near-infrared light sources, etc. (hereinafter referred to as "near-infrared phosphors") can be used.

[0091] The light emitting device 10A uses a phosphor that emits wavelength-converted near-infrared light on the relatively short wavelength side, which has a maximum fluorescence intensity within a wavelength range of 700 nm or more and less than 1700 nm, as the second phosphor 2, and obtains output light 4 that includes optical components with the absorption wavelengths of various gas molecules. The absorption wavelengths of various gas molecules are, for example, O2: 760 nm, NO2: 830 nm, H2O: 1365 nm, NH3: 1530 nm, C2H2: 1530 nm, CO: 1567 nm, CO2: 1573 nm, and CH4: 1651 nm.

[0092] The output light 4 is obtained by the light-emitting device 10A in which the first transmitted primary light 3BT1, the primary light 3B, or the first wavelength-converted light 1B is light that exhibits an intensity maximum value within a visible wavelength range of, for example, 380 nm or more and less than 700 nm. The output light 4 is obtained by the light-emitting device 10A in which the first transmitted primary light 3BT1, the primary light 3B, or the first wavelength-converted light 1B is preferably blue to blue-green light that exhibits an intensity maximum value within a wavelength range of 440 nm or more and less than 500 nm. The output light 4 is obtained by the light-emitting device 10A in which the first transmitted primary light 3BT1, the primary light 3B, or the first wavelength-converted light 1B is preferably green to yellow light that exhibits an intensity maximum value within a wavelength range of 500 nm or more and less than 580 nm. The output light 4 is obtained by the light-emitting device 10A in which the first transmitted primary light 3BT1, the primary light 3B, or the first wavelength-converted light 1B is preferably red light that exhibits an intensity maximum value within a wavelength range of 600 nm or more and less than 680 nm.

[0093] If the second phosphor 2 is a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of less than 800 nm±100 nm, this is desirable for applications in which near-infrared spectroscopy is used to obtain information about an irradiated object that contains oxygen (O2), nitrogen dioxide (NO2) and these components. For the same reason, it is more desirable for the second phosphor 2 to be a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of less than 800 nm±50 nm.

[0094] If the second phosphor 2 is a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of less than 1350 nm±150 nm, preferably less than 1350 nm±75 nm, it is desirable for use in obtaining information about water (HO) and irradiated objects that contain water.

[0095] The second phosphor 2 is preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of less than 1600 nm±200 nm. Such a second phosphor 2 is desirable for applications in which information about irradiated objects containing ammonia (NH3), hydrocarbons (C2H2, CH4, etc.), carbon oxides (CO, CO2, etc.) and components thereof is obtained. For the same reason, the second phosphor 2 is more preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of less than 1600 nm±100 nm.

[0096] Conversely, the second phosphor 2 may be a phosphor in which the maximum intensity of the light component in the wavelength range of less than 800 nm±50 nm is less than 10% of the maximum intensity in the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution. In this embodiment, a phosphor that does not have a light component in the wavelength range of less than 800 nm±50 nm is particularly preferable. The reason why this second phosphor 2 is preferable is that it can avoid the adverse effects that light absorption by oxygen (O2) or nitrogen dioxide (NO2) has on the irradiated object, system, etc.

[0097] For the same reason, it is more preferable that the second phosphor 2 is a phosphor in which the maximum intensity of the light component within the wavelength range of 800 nm±100 nm is less than 10% of the maximum intensity within the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution.

[0098] It is also preferable that the second phosphor 2 is a phosphor in which the maximum intensity of the light component in the wavelength range of less than 1350 nm±75 nm is less than 10% of the maximum intensity in the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution. In this embodiment, a phosphor that does not have a light component in the above wavelength range, such as less than 1350 nm±75 nm, is particularly preferable. The reason why this second phosphor 2 is preferable is that it can avoid the adverse effects of light absorption by water (H2O) on the irradiated object, system, etc.

[0099] For the same reason, it is more preferable that the second phosphor 2 is a phosphor in which the maximum intensity of the light component within the wavelength range of 1350 nm±150 nm is less than 10% of the maximum intensity within the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution.

[0100] It is also preferable that the second phosphor 2 is a phosphor in which the maximum intensity of the light component in the wavelength range of less than 1600 nm±100 nm is less than 10% of the maximum intensity in the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution. In this embodiment, a phosphor that does not have a light component in the above wavelength range, such as less than 1600 nm±100 nm, is particularly preferable. The reason why such a second phosphor 2 is preferable is that it can avoid the adverse effects that light absorption by ammonia (NH3), hydrocarbons (C2H2, CH4, etc.), or carbon oxides (CO, CO2, etc.) has on the irradiated object, system, etc.

[0101] For the same reason, it is more preferable that the second phosphor 2 is a phosphor in which the maximum intensity of the light component within the wavelength range of 1600 nm±200 nm is less than 10% of the maximum intensity within the wavelength range of 700 nm or more and less than 1700 nm of the spectral distribution.

[0102] The light emitting device 10A using the phosphor that emits wavelength-converted light of near-infrared on the relatively short wavelength side outputs light components with high spectral sensitivity to photodiodes used exclusively in sensors for detectors, and therefore the light emitting device 10A using the phosphor that emits wavelength-converted light of near-infrared on the relatively short wavelength side is desirable for use in inspection devices that use photodiodes.

[0103] The second phosphor 2 is preferably a phosphor that emits wavelength-converted light that shows a maximum fluorescence intensity within a wavelength range of 700 nm or more and less than 1100 nm, which is desirable for applications in which a light-emitting device for an inspection device using a Si photodiode or a Si-PIN photodiode is provided. For the same reason, the second phosphor 2 is more preferably a phosphor that emits wavelength-converted light that shows a maximum fluorescence intensity within a wavelength range of preferably 780 nm or more and less than 1050 nm, more preferably 800 nm or more and less than 1000 nm.

[0104] The second phosphor 2 is preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of 700 nm or more and less than 1600 nm, which is desirable for applications in which a light-emitting device for an inspection device using a Ge photodiode is provided. For the same reason, the second phosphor 2 is more preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of preferably 1100 nm or more and less than 1550 nm, more preferably 1300 nm or more and less than 1500 nm.

[0105] The second phosphor 2 is preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of 900 nm or more and less than 1650 nm, which is desirable for applications in which a light-emitting device for an inspection device using an InGaAs photodiode is provided. For the same reason, the second phosphor 2 is more preferably a phosphor that emits wavelength-converted light that exhibits a maximum fluorescence intensity within a wavelength range of preferably 1000 nm or more and less than 1600 nm, more preferably 1100 nm or more and less than 1600 nm.

[0106] In addition, the light emitting device 10A using the phosphor that emits wavelength-converted light of near-infrared on the relatively short wavelength side described above has a lower risk of outputting light components of 4000 nm or more that become heat rays. Therefore, these light emitting devices 10A are desirable for use in the inspection of irradiated objects that are easily altered by heat if they are not designed to output the above light components.

[0107] When a phosphor that emits wavelength-converted near-infrared light on the relatively long wavelength side, showing a maximum fluorescence intensity within a wavelength range of 780 nm or more and less than 2500 nm, is used as the second phosphor 2, it is possible to obtain a light emitting device 10A that emits output light 4 that includes an infrared light component that is invisible to the human eye. When a phosphor that emits wavelength-converted near-infrared light on the relatively long wavelength side, showing a maximum fluorescence intensity within a wavelength range of preferably 800 nm or more and less than 2500 nm, is used as the second phosphor 2, it is possible to obtain a light emitting device 10A that emits output light 4 that includes an infrared light component that is invisible to the human eye.

[0108] These light emitting devices 10A are obtained when the first transmitted primary light 3BT1, the primary light 3B or the first wavelength converted light 1B is light that exhibits an intensity maximum within the visible wavelength range of, for example, 380 nm or more and less than 700 nm.

[0109] Such light emitting devices 10A using phosphors that emit wavelength-converted light in the near-infrared region on the relatively long wavelength side have a lower risk of outputting visible light components with wavelengths shorter than 780 nm that are visible to the human eye. For this reason, if these light emitting devices 10A are designed not to output the above-mentioned visible light components, they are desirable for use in surveillance and other applications where it is inconvenient for people to notice the presence of the output light 4.

[0110] As the second phosphor 2, for example, a phosphor activated with rare earth ions, transition metal ions, etc., and emitting fluorescence containing a near-infrared light component can be used. As the rare earth ions, for example, Nd 3+ ,EU 2+ , Ho 3+ , Er 3+ , Tm 3+ and Yb 3+ At least one selected from the following is used. The transition metal ion is, for example, Ti 3+ , V 4+ , Cr 4+ , V 3+ , Cr 3+ , V 2+ , Mn 4+ , Fe 3+ , Co 3+ , Co 2+ and Ni 2+ At least one selected from the following is used.

[0111] As the second phosphor 2, similar to the first phosphor 1, oxides, sulfides, nitrides, halides, oxysulfides, oxynitrides, oxyhalides, etc. containing rare earth ions, transition metal ions, etc. as fluorescent ions can be used.

[0112] The ions constituting the second phosphor 2 and functioning as fluorescent ions of an inorganic compound can be at least one type of ion selected from the rare earth ions and transition metal ions. The ions functioning as fluorescent ions are those that function as fluorescent ions of a phosphor having the property of absorbing at least one of the first transmitted primary light 3BT1, the primary light 3B, and the first wavelength-converted light 1B and converting it into a near-infrared light component. The ions functioning as fluorescent ions are preferably Cr 3+ That is, the second phosphor 2 preferably contains Cr as a fluorescent ion. 3+ Includes.

[0113] The second phosphor 2 is Cr 3+ When the second phosphor 2 contains Cr, it is preferable that the second phosphor 2 contains Cr because the second phosphor 2 is likely to have a property of absorbing visible light, particularly blue light or red light, and converting it into a near-infrared light component. 3+ In the case where the phosphor contains the above-mentioned inorganic compound, it is easy to change the light absorption peak wavelength and the fluorescence peak wavelength depending on the type of inorganic compound that is the host material of the phosphor, and it is also easy to change the shape of the excitation spectrum, the fluorescence spectrum, and the like.

[0114] The second phosphor 2 is Cr 3+ When the second phosphor 2 contains Cr, it becomes easy to use the blue light component emitted by a wavelength-converted light-emitting element having a blue LED specification that is easily available as excitation light. Here, as a wavelength-converted light-emitting element having a blue LED specification that is easily available, for example, a light-emitting element that combines a solid-state light-emitting element and a phosphor is used. For this reason, when the second phosphor 2 contains Cr, 3+ This provides a light emitting device 10A that is suitable for rapid manufacture and sale.

[0115] Furthermore, the second phosphor 2 is Cr 3+ When a wavelength conversion type light emitting element including a red phosphor is used, the red light component suitable for reducing the Stokes loss can be easily used as excitation light.

[0116] Therefore, the second phosphor 2 is Cr 3+ With this configuration, a light emitting device 10A suitable for controlling the spectral distribution of the output near-infrared light component can be obtained.

[0117] The fluorescent ions are Cr 3+ The type of phosphor that becomes the first transmitted primary light 3BT1, the primary light 3B, and the first wavelength converted light 1B is not particularly limited as long as it absorbs at least one of them and converts it into an infrared fluorescent component. 3+ The second phosphor 2 is the known Cr 3+ It is sufficient to select an appropriate phosphor from the list of phosphors that are activated. 3+ As the second phosphor 2, for example, a composite metal oxide that is easy to manufacture can be used.

[0118] The fluorescent ion is Cr 3+ Specifically, the second phosphor 2 is Cr, which has a garnet-type crystal structure and has a proven track record. 3+ The complex oxide phosphor activated with Cr 3+ Cr is used as the activated garnet phosphor. 3+ As the activated garnet phosphor, a rare earth aluminum garnet phosphor is preferably used. 3+ More specifically, the activated garnet phosphor is Y3Al2(AlO4)3:Cr 3+ , La3Al2(AlO4)3:Cr 3+ , Gd3Al2(AlO4)3:Cr 3+ , Y3Ga2(AlO4)3:Cr 3+ , La3Ga2(AlO4)3:Cr 3+ , Gd3Ga2(AlO4)3:Cr 3+ , Y3Sc2(AlO4)3:Cr 3+ , La3Sc2(AlO4)3:Cr 3+ , Gd3Sc2(AlO4)3:Cr 3+ , Y3Ga2(GaO4)3:Cr 3+ , La3Ga2(GaO4)3:Cr 3+ , Gd3Ga2(GaO4)3:Cr 3+ , Y3Sc2(GaO4)3:Cr 3+ , La3Sc2(GaO4)3:Cr 3+ , Gd3Sc2(GaO4)3:Cr 3+and garnet compounds consisting of solid solutions of these substances as end members.

[0119] Cr 3+ Many activated garnet phosphors have the property of absorbing blue to red light components, especially blue or red light components, and converting them into deep red to near infrared light. Therefore, a solid-state light-emitting element 3 that emits blue light and / or red light components and a phosphor that emits blue light and / or red light components can be used as the solid-state light-emitting element 3 that emits primary light 3B and / or the first wavelength converter 1A that emits first wavelength-converted light 1B. Cr 3+ By using an activated garnet phosphor, a light emitting device 10A can be obtained that can easily obtain output light 4 that contains at least one type (blue or red) of light component that constitutes the three primary colors of light (blue, green, red) and at least a near-infrared light component.

[0120] As a light emitting device 10A capable of obtaining output light 4 with high color rendering properties containing light components constituting the three primary colors of light (blue, green, red) and a near-infrared light component, for example, one comprising a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A as described below is used. In this light emitting device 10A, first, a solid-state light emitting element 3 that emits blue light as primary light 3B is used as the solid-state light emitting element 3. Second, in the light emitting device 10A, a Ce phosphor that converts blue light into green light is used as the first phosphor 1. 3+ Activated garnet phosphor, and / or Eu for converting at least blue light to red light 2+ Thirdly, in the light emitting device 10A, a first wavelength converter 1A containing an activated nitride phosphor is used as the second phosphor 2. The second phosphor 2 is a Cr phosphor that converts at least one of the first transmitted primary light 3BT1, the primary light 3B, and the first wavelength converted light 1B into near infrared light. 3+ A second wavelength converter 2A containing an activated garnet phosphor is used.

[0121] In recent years, Ce 3+ The material technology for activated garnet phosphors, including ceramics technology, has progressed, so Ce 3+ Cr, a technology developed with activated garnet phosphors 3+It is easy to apply to activated garnet phosphors. 3+ By using fluorescent ceramics mainly composed of activated garnet phosphor, it is relatively easy to provide a light emitting device 10A that is favorable in terms of high output of near-infrared light components and reliability.

[0122] In addition, like white LED light sources, Ce 3+ There are a wide variety of activated garnet phosphors on the market, and many companies manufacture and sell them, so the related technology is easily available. 3+ We expect to expand the technology we have developed for activated garnet phosphors. 3+ By using an activated garnet phosphor, a light emitting device 10A suitable for rapid product development with little effort can be obtained.

[0123] (Second wavelength converted light 2B) In the light emitting device 10A, the second wavelength converter 2A absorbs at least a part of the first mixed light 14 containing the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first converted wavelength light 1B. The second wavelength converter 2A then converts the first mixed light 14 into second converted wavelength light 2B having a fluorescence peak in a wavelength range exceeding 700 nm and having a near-infrared component in the wavelength range of 780 nm or more and less than 2500 nm.

[0124] The second wavelength-converted light 2B is, for example, a near-infrared light component having a maximum intensity within a wavelength range of 700 nm or more and less than 2500 nm, and is also, for example, a light component having a maximum intensity within a wavelength range of 750 nm or more and less than 1800 nm, preferably 780 nm or more and less than 1500 nm.

[0125] (Output light 4) The output light 4 includes at least a transmitted first wavelength-converted light 1BT2, which is a light component of the first wavelength-converted light 1B transmitted through the second wavelength converter 2A, and a light component of the second wavelength-converted light 2B. Here, the transmitted first wavelength-converted light 1BT2 is light of lower intensity than the first wavelength-converted light 1B. The spectral distribution of the transmitted first wavelength-converted light 1BT2 is derived from the spectral distribution of the first wavelength-converted light 1B.

[0126] The output light 4 may further include second transmitted primary light 3BT2 which is the first transmitted primary light 3BT1 transmitted through the second wavelength-converted light 2B. Fig. 1 shows an embodiment in which the output light 4 is second mixed light 24 which includes the transmitted first wavelength-converted light 1BT2, the second wavelength-converted light 2B, and the second transmitted primary light 3BT2. Although the output light 4 and the second mixed light 24 are the same light, for convenience, the output light 4 is also referred to as the second mixed light 24.

[0127] FIG. 4 shows an example of the spectral distribution of output light 4 emitted by the light emitting device according to this embodiment.

[0128] The output light 4 emitted by the light emitting device according to this embodiment can include, for example, at least a first light component 5, a second light component 6, and a third light component 7, each having a different color tone, as shown in FIG.

[0129] Here, the first light component 5 is a light component derived from the primary light 3B emitted by the solid-state light-emitting element 3. The first light component 5 shown in Fig. 4 is the same as the second transmitted primary light 3BT2 shown in Fig. 1. Although the first light component 5 and the second transmitted primary light 3BT2 are the same light component, they are expressed differently for convenience of explanation.

[0130] The first light component 5 is, for example, a visible light component having an intensity maximum value within a wavelength range of 300 nm or more and less than 660 nm, preferably 380 nm or more and less than 670 nm, and more preferably 435 nm or more and less than 470 nm. The first light component 5 shown in FIG. 4 has an intensity maximum value at 455 nm.

[0131] Moreover, the second light component 6 is a light component derived from the first wavelength-converted light 1B emitted by the first phosphor 1. The second light component 6 shown in Fig. 4 is the same as the transmitted first wavelength-converted light 1BT2 shown in Fig. 1. Although the second light component 6 and the transmitted first wavelength-converted light 1BT2 are the same light component, they are expressed differently for ease of explanation.

[0132] The second light component 6 is, for example, a visible light component having an intensity maximum within a wavelength range of 380 nm or more and less than 700 nm, preferably 500 nm or more and less than 660 nm. The second light component 6 shown in FIG. 4 has an intensity maximum at 540 nm.

[0133] Furthermore, the third light component 7 is a light component originating from the second wavelength-converted light 2B emitted by the second phosphor 2. The third light component 7 shown in Fig. 4 is the same as the second wavelength-converted light 2B shown in Fig. 1. Although the third light component 7 and the second wavelength-converted light 2B are the same light component, they are expressed differently for convenience of explanation.

[0134] The third light component 7 is, for example, near-infrared light having a maximum intensity within a wavelength range of 700 nm or more and less than 2500 nm, preferably 750 nm or more and less than 1800 nm. The longest wavelength in this wavelength range can be appropriately set to 800 nm, 900 nm, 1000 nm, 1200 nm, 1500 nm, etc. The third light component 7 shown in FIG. 4 has a maximum intensity at 730 nm.

[0135] According to the light emitting device 10A that emits the output light 4 having the above-mentioned first light component 5, second light component 6, and third light component 7, the output light 4 contains a visible light component that can be seen by the human eye and a near-infrared light component that is difficult to see by the human eye. Here, the visible light components are the first light component 5 and the second light component 6, and the near-infrared light component is the third light component 7. According to the light emitting device 10A, it is possible to perform non-destructive inspection of the inside of an illuminated object by using near-infrared spectroscopy or the like while checking the illuminated object with the human eye.

[0136] Furthermore, according to the light emitting device 10A, output light 4 having a color tone resulting from additive mixing of primary light 3B (first light component 5) and first wavelength-converted light 1B and / or second wavelength-converted light 2B (second light component 6 and / or third light component 7) is obtained.

[0137] According to the light emitting device 10A, the total number of photons in the output light 4 can be controlled by controlling the power supplied to the solid-state light emitting element 3. Moreover, according to the light emitting device 10A, the ratio of photons constituting the first light component 5, the second light component 6, and the third light component 7 can be controlled by changing the thickness and light transmittance of the first wavelength converter 1A and the second wavelength converter 2A. Furthermore, according to the light emitting device 10A, the color tones of the second light component 6 and the third light component 7 can be controlled by changing the types of the first phosphor 1 and the second phosphor 2.

[0138] Therefore, the light emitting device 10A can easily meet both customer needs regarding visibility of an illuminated object and non-destructive inspection of the object, etc. Also, the light emitting device 10A emits output light that makes an illuminated object look natural, which is suitable for both the human eye and a detector.

[0139] It is desirable that the spectral distribution of output light 4 has a valley within a wavelength range of 650 nm or more and less than 800 nm, preferably 700 nm ± 50 nm. It is desirable that the minimum intensity value within the above wavelength range having the valley of the spectral distribution of output light 4 is less than 50% of the maximum intensity value of the spectral distribution within a wavelength range of 380 nm or more and 2500 nm or less, preferably 380 nm or more and 960 nm or less.

[0140] With this configuration, the output light 4 has less interference between the first mixed light 14 of the first light component 5 and the second light component 6, which are mainly composed of visible light components, and the third light component 7, which has a near-infrared light component. Specifically, the spectral distribution of the output light 4 is a spectral distribution in which the visible light component and the near-infrared light component are separated to a certain degree or more, with the wavelength of about 700 nm as the boundary. Therefore, the light emitting device 10A that emits such output light 4 tends to improve the S / N ratio of a detector that detects the near-infrared light component transmitted through the illuminated object or reflected by the illuminated object.

[0141] In addition, in applications where the near-infrared light component emitted by the light source is detected by a detector and the detection signal of the detector is Fourier transformed for use (for example, optical coherence tomography), the spectral distribution of the third light component 7 is preferably unimodal. In the above applications, it is more preferable that the third light component 7 has a spectral distribution that has a normal distribution or is close to it.

[0142] In this case, it is preferable that the spectral distribution of the third light component 7 does not involve a sudden change in the wavelength dependence of intensity in the wavelength region beyond 700 nm, and it is more preferable that it does not change by more than ±8% / nm, in particular ±3% / nm.

[0143] The degree of the preferable spectral distribution close to the normal distribution is expressed numerically. The wavelength at which the third light component 7 exhibits the maximum intensity is defined as λ P The wavelengths on the short wavelength side and the long wavelength side at which the intensity of the third light component 7 is half the maximum intensity are respectively defined as λ S and λ L In this case, λ P and λ S and λ L For example, 1≦(λ L -λ P ) / (λ P -λ S )<2.0, preferably 1≦(λ L -λ P ) / (λ P -λ S ) < 1.8.

[0144] When the spectral distribution of the third light component 7 satisfies this condition, the generation of spurious signals after Fourier transform can be suppressed, and a light emitting device suitable for allowing a detector to detect a detection signal with excellent signal quality can be obtained.

[0145] Here, it is desirable that at least one of the first light component 5 and the second light component 6 has a blue-green to green to yellow to orange light component with a wavelength of 510 nm or more and less than 600 nm, preferably a green to yellow light component with a wavelength of 530 nm or more and less than 580 nm. It is more desirable that at least one of the first light component 5 and the second light component 6 has a green light component with a wavelength of 545 nm or more and less than 565 nm.

[0146] With this configuration, the light emitting device 10A can be obtained that emits output light 4 that is easily recognized by the human eye as an illuminated object, since the light emitting device 10A outputs light components with a wavelength that is perceived as bright and has a high intensity by the human eye.

[0147] In the light emitting device 10A, at least one of the first light component 5 and the second light component 6 has a blue to blue-green to green light component with a wavelength of 460 nm or more and less than 550 nm, preferably a blue-green to green light component with a wavelength of 480 nm or more and less than 530 nm. At least one of the first light component 5 and the second light component 6 preferably has a blue-green to green light component with a wavelength of 490 nm or more and less than 520 nm.

[0148] With this configuration, a light emitting device 10A can be obtained that outputs light components with wavelengths that are perceived by the human eye as bright and have a high intensity in scotopic vision where the amount of light is small. In other words, a light emitting device 10A can be obtained that emits output light 4 that makes it easy to view an illuminated object in the dark.

[0149] In the light emitting device 10A, at least one of the first light component 5 and the second light component 6 preferably has a red light component with a wavelength of 610 nm or more and less than 670 nm, preferably 630 nm or more and less than 660 nm.

[0150] With this configuration, it is possible to obtain a light emitting device 10A that outputs light components that make the flesh color or red of an illuminated object look beautiful or vivid. In other words, it is possible to obtain a light emitting device 10A that emits output light 4 that improves the appearance of an illuminated person's face or skin, or the appearance of reddish meat or fruit.

[0151] The third light component 7 preferably has an intensity that decreases with increasing wavelength from 850 nm, and the fluorescence intensity at 1000 nm can be set to less than 10% of the fluorescence intensity at 850 nm. The starting wavelength is preferably shorter than 850 nm, and can be set to, for example, 800 nm. In this case, the fluorescence intensity at 1000 nm can be set to less than 10% of the fluorescence intensity at 800 nm, and the fluorescence intensity at 950 nm can be set to less than 10% of the fluorescence intensity at 800 nm.

[0152] With this configuration, a light emitting device 10A can be obtained that emits output light 4 with a small proportion of near-infrared rays and mid-infrared rays in the long wavelength region that tend to function as heat rays. That is, a light emitting device 10A suitable for use in inspecting irradiated objects that are easily adversely affected by the heat emitted by the light emitting device, such as food, can be obtained.

[0153] The spectral distribution of output light 4 has a minimum value between the second light component 6 and the third light component 7, and this minimum value is preferably less than 50% of the maximum intensity of the third light component 7. Furthermore, it is desirable that the spectral distribution of output light 4 has a wavelength difference between the long wavelength side wavelength and the short wavelength side wavelength at which the third light component has an intensity of 50% of its maximum intensity exceeding 70 nm, preferably 100 nm.

[0154] With this configuration, the light emitting device 10A can be obtained that emits output light 4 with good separation between visible and near-infrared light components and with near-infrared light components of different wavelengths over a wide wavelength range. In other words, the light emitting device 10A can be obtained that is suitable for inspecting and evaluating irradiated objects whose optical absorption wavelengths of near-infrared light are different or that are prone to change depending on the surrounding environment.

[0155] In such a configuration, the light obtained by mixing the first light component 5, the second light component 6, and the third light component 7 preferably includes a blue light component, a blue-green-green-yellow light component, and a red light component. Here, the blue light component is preferably a blue light component having a wavelength range of 435 nm or more and less than 480 nm. The blue-green-green-yellow light component is preferably a blue-green-green-yellow light component having a wavelength range of 500 nm or more and less than 580 nm. The red light component is preferably a red light component having a wavelength range of 600 nm or more and less than 700 nm.

[0156] The blue light component is preferably a blue light component having an intensity maximum within the wavelength range. The blue-green-green-yellow light component is preferably a green-green-yellow light component having an intensity maximum within the wavelength range. The red light component is preferably a red light component having an intensity maximum within the wavelength range.

[0157] With this configuration, the output light 4 contains blue, green, and red light components, which are the three primary colors of light, and a light emitting device 10A capable of outputting visible light with high color rendering properties is obtained. In other words, a light emitting device 10A suitable for making an illuminated object appear as it is is obtained. Furthermore, with this configuration, a light emitting device 10A that emits a large amount of the three primary colors of light (blue, green, and red) and near-infrared light components is obtained, and therefore the light emitting device 10A is compatible with imaging technology called RGB-NIR imaging.

[0158] In such a configuration, the first light component 5 can be a blue light component originating from the primary light 3B emitted by the solid-state light-emitting element 3 and having an intensity maximum value typically within a wavelength range of 435 nm or more and less than 480 nm, preferably 440 nm or more and less than 470 nm.

[0159] The output light 4 of such a configuration can be easily obtained by using an orthodox solid-state light-emitting element such as a light-emitting diode (LED) that emits blue light, a laser diode (LD), etc. Therefore, with such a configuration, a light-emitting device 10A suitable for speedy product development and industrial production can be obtained.

[0160] The second light component 6 is preferably light originating from the first wavelength-converted light 1B of the first light component 5 by the first phosphor 1.

[0161] With this configuration, a light emitting device 10A can be obtained that reduces the energy difference (Stokes shift) between the light absorption and the fluorescent emission by the first phosphor 1. In other words, with this configuration, the first phosphor 1 generates heat due to the energy loss that occurs with the wavelength conversion from visible light to visible light with a longer wavelength, and the phenomenon of quenching due to the temperature rise of the phosphor (called temperature quenching) is suppressed. Therefore, with this configuration, a light emitting device 10A suitable for outputting the second light component 6 with high photon conversion efficiency can be obtained.

[0162] The third light component 7 is preferably the second wavelength-converted light 2B of the second light component 6 by the second phosphor 2.

[0163] With this configuration, a light emitting device 10A is obtained that reduces the energy difference between the light absorption and the fluorescent emission by the second phosphor 2. That is, with this configuration, the second phosphor 2 generates heat due to the energy loss that occurs with the wavelength conversion from visible light to near-infrared light, which has a longer wavelength, and quenching due to the temperature rise of the phosphor is suppressed. Therefore, with this configuration, a light emitting device suitable for outputting the third light component 7 with high photon conversion efficiency is obtained.

[0164] The output light 4 can be configured so that the integral value of the energy intensity of the light components having a wavelength of less than 700 nm is greater than the integral value of the energy intensity of the light components having a wavelength of 700 nm or more. With this configuration, the light emitting device 10A can be obtained in which the integral value of the energy intensity of the light components having a wavelength of less than 700 nm is more than twice, preferably three times, the integral value of the energy intensity of the light components having a wavelength of 700 nm or more.

[0165] For this reason, with this configuration, a light emitting device 10A can be obtained in which the energy intensity of the visible light component with high luminosity is greater than the energy intensity of the long wavelength light component including near infrared light with low luminosity. In other words, a light emitting device 10A can be obtained that emits output light that makes the illuminated object bright and easy to see for the human eye and allows non-destructive testing of the illuminated object, if necessary.

[0166] Conversely, light emitting device 10A may be configured such that the integral value of the energy intensity of light components having wavelengths less than 700 nm is smaller than the integral value of the energy intensity of light components having wavelengths of 700 nm or more in output light 4. With such a configuration, light emitting device 10A is obtained in which the integral value of the energy intensity of light components having wavelengths less than 700 nm is less than half, preferably less than one-third, of the integral value of the energy intensity of light components having wavelengths of 700 nm or more.

[0167] Therefore, with this configuration, a light emitting device 10A is obtained in which the energy intensity of the light components including the near-infrared light components that can be used for non-destructive testing, etc., is greater than the energy intensity of the light components that are visible to the human eye. That is, with this configuration, a light emitting device 10A is obtained that emits output light 4 that is suitable for high-precision non-destructive testing, non-destructive testing of minute objects, non-destructive testing of wide areas, non-destructive testing of large or thick irradiated objects, etc. Also, with this configuration, a light emitting device 10A is obtained that emits output light 4 that allows the surface condition of the illuminated irradiated object to be easily confirmed by the human eye, as necessary. Furthermore, with this configuration, a light emitting device 10A is obtained that emits output light with a small output ratio of visible light components that are visible to the human eye, and thus a light emitting device 10A that is suitable for reducing the glare of the output light 4 is obtained.

[0168] The light emitting device 10A can be configured to emit white output light 4. For example, the first light component 5, the second light component 6, and the third light component 7 can be combined with appropriate light components that form white light by additive color mixing to obtain the light emitting device 10A that emits white output light 4.

[0169] With this configuration, the light emitting device 10A can be obtained that simultaneously emits light with a color tone close to natural light and high-power near-infrared light, and serves both general and industrial purposes. Therefore, the light emitting device 10A can be obtained that has a natural appearance of an illuminated object and is suitable for applications such as a detection device that detects the state of an illuminated object, and an inspection device that inspects the internal structure and defects of an illuminated object.

[0170] The output light 4 is light having a color whose correlated color temperature is preferably 2600K or more and less than 12000K, and more preferably 3000K or more and less than 8000K.

[0171] With this configuration, the light emitting device 10A can be obtained that simultaneously emits visible light with a color tone close to natural light and near-infrared light, and can be used for both general lighting, where importance is placed on how it looks to the human eye, and industrial lighting, where importance is placed on how it looks to the eyes (sensors) of electronic devices. That is, the light emitting device 10A can be obtained that gives a natural appearance to an illuminated object and is suitable for applications such as a detection device that detects the state of an illuminated object, or an inspection device that can inspect the internal structure or defects of an illuminated object. Note that light with a low correlated color temperature has a color close to that of light emitted by a light bulb, and light with a high correlated color temperature has a color close to that of sunlight in the daytime.

[0172] In this embodiment, the general color rendering index (Ra) of the output light 4 is preferably 80 or more and less than 100.

[0173] Such light emitting device 10A uses light with high color rendering properties to make the irradiated objects, such as fruits and vegetables, meat, and fresh fish, appear fresh and attractive, and also makes it possible to evaluate the degree of spoilage and freshness of the inside of the irradiated objects by detecting the light components of reflected or transmitted near-infrared light.

[0174] Furthermore, the light-emitting device 10A can be used for store lighting, for example, to enable the degree of spoilage of fruits and vegetables and other products displayed in a sales area to be grasped without a third party realizing, and to enable products that are found to be damaged to be removed early from the regular price sales area, etc.

[0175] Furthermore, the light emitting device 10A is suitable for healthcare or medical applications that use light with high color rendering properties to make irradiated objects such as a human face, skin, and internal organs look beautiful, and that enable evaluation of a person's health condition, illness, and the like by detecting the light components of reflected or transmitted near-infrared light. Here, the reflected or transmitted near-infrared light is light based on near-infrared that illuminates an irradiated object. Light with a small average color rendering index is suitable for high luminous flux, and light with a large average color rendering index is close to natural light.

[0176] According to the light emitting device 10A, while the space appears to be comparable to that illuminated by natural light, it is possible to monitor and measure the state of the illuminated object by near-infrared light without being noticed by a person.

[0177] The white output light 4 can have a spectral intensity over the entire wavelength range of at least 440 nm or more and less than 660 nm, preferably at least 430 nm or more and less than 900 nm. In other words, the white output light 4 can have a spectral distribution that does not include any wavelength components whose intensity is zero within the above-mentioned wavelength range.

[0178] Using such output light 4, it is possible to illuminate an object with many lights of different wavelengths. In addition, by using output light 4 ranging from short-wavelength visible (purple-blue) to near-infrared, it is possible to obtain a light-emitting device 10A suitable for hyperspectral imaging, which captures and collects reflected light that differs depending on the illuminating wavelength, and visualizes the characteristics of the illuminated object.

[0179] The spectral distribution of output light 4 emitted by the light emitting device preferably has a maximum intensity (maximum intensity) for light components with long wavelengths of 700 nm or more. Also, the spectral distribution of output light 4 preferably has a maximum intensity for light components with wavelengths of 700 nm or more that is 1.5 times, preferably 2 times, more preferably 3 times the maximum intensity for light components with wavelengths of 380 nm or more and less than 700 nm.

[0180] Furthermore, the maximum intensity of the light component in the wavelength range of 380 nm or more and less than 700 nm is preferably less than 50% of the maximum intensity of the light component with a wavelength of 700 nm or more, more preferably less than 30%, and even more preferably less than 10%. This provides light emitting device 10A with a high proportion of near-infrared light components and high conversion efficiency to near-infrared light components.

[0181] The spectral distribution of output light 4 emitted by the light emitting device preferably has a maximum intensity (maximum intensity) for light components with wavelengths of 380 nm or more and less than 700 nm. Also, the spectral distribution of output light 4 preferably has a maximum intensity for light components with wavelengths less than 700 nm that is 1.5 times, preferably 2 times, more preferably 3 times the maximum intensity for light components with wavelengths of 700 nm or more. With this configuration, a light emitting device 10A is obtained that has a high proportion of visible light components and a high conversion efficiency to visible light components.

[0182] It is preferable that the spectral distribution of output light 4 does not substantially include light components in the ultraviolet region with wavelengths less than 380 nm. With such a configuration, it is possible to obtain light emitting device 10A that can convert input power only into visible light and infrared light including near-infrared light, and has high energy conversion efficiency into visible light and infrared light.

[0183] The spectral distribution of the output light is shown as the third light component 7 in FIG. 3+ Ion 4 T2 → 4 It is preferable that the light emitting device 10A emits a broad fluorescent component derived from the electronic energy transition of A2. In addition, it is preferable that the fluorescent component has a fluorescent peak in a wavelength region of 700 nm or more. This allows the light emitting device 10A to emit near-infrared light components over a wide wavelength range, making it suitable for hyperspectral imaging.

[0184] The spectral distribution of the output light 4 preferably has light components over the entire visible wavelength range of at least 410 nm or more and less than 700 nm, and preferably 380 nm or more and less than 780 nm. With such a configuration, a light emitting device 10A can be obtained that emits output light having light components that can be used for spectral imaging over the entire visible wavelength range, as well as allowing illuminated objects to be visually recognized by the human eye.

[0185] (Operation of the light emitting device) The operation of the light emitting device 10A will be described below with reference to FIG.

[0186] When the solid-state light-emitting element 3 is driven by supplying power, the solid-state light-emitting element 3 emits primary light 3B. When the primary light 3B emitted from the solid-state light-emitting element 3 enters the first wavelength converter 1A, the first wavelength converter 1A absorbs a part of the primary light 3B and converts it into first wavelength-converted light 1B, which has lower light energy. When the primary light 3B passes through the first wavelength converter 1A, it becomes first transmitted primary light 3BT1. A first mixed light 14, which is a mixed light of the first transmitted primary light 3BT1 and the first wavelength-converted light 1B, is emitted from the first wavelength converter 1A.

[0187] When the first mixed light 14 enters the second wavelength converter 2A, the second wavelength converter 2A absorbs a part of the mixed light and converts it into second wavelength-converted light 2B having lower light energy. The first transmitted primary light 3BT1 becomes second transmitted primary light 3BT2 when it passes through the second wavelength converter 2A. The first wavelength-converted light 1B becomes transmitted first wavelength-converted light 1BT2 when it passes through the second wavelength converter 2A. The second mixed light 24, which is a mixed light of the second transmitted primary light 3BT2, the transmitted first wavelength-converted light 1BT2, and the second wavelength-converted light 2B, is emitted from the second wavelength converter 2A. The second mixed light 24 becomes the output light 4.

[0188] The primary light 3B, the first wavelength-converted light 1B, and the second wavelength-converted light 2B are the sources for forming the first light component 5 (the second transmitted primary light 3BT2), the second light component 6 (the transmitted first wavelength-converted light 1BT2), and the third light component 7 (the second wavelength-converted light 2B), respectively. They form a spectral distribution and are output as the output light 4.

[0189] [Second embodiment] 2 includes a solid-state light-emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A. Specifically, the light-emitting device 10B according to the second embodiment is a light-emitting device provided with a plurality of light-emission-wavelength conversion units, which are combination structures of the solid-state light-emitting element 3 and the first wavelength converter 1A.

[0190] The light emitting device 10B according to the second embodiment is the same as the light emitting device 10A according to the first embodiment, except that it is provided with a plurality of light emission-wavelength conversion units. For this reason, the same members in the light emitting device 10B according to the second embodiment and the light emitting device 10A according to the first embodiment are denoted by the same reference numerals, and descriptions of these members are omitted.

[0191] (Operation of the light emitting device) In the operation of the light emitting device 10A according to the first embodiment, the multiple first wavelength converters 1A constituting one light emission-wavelength converting unit emit the first mixed light 14. On the other hand, in the operation of the light emitting device 10B according to the second embodiment, each of the multiple first wavelength converters 1A constituting the multiple light emission-wavelength converting units emits the first mixed light 14.

[0192] The operation of the light emitting device 10B according to the second embodiment is the same as that of the light emitting device 10A according to the first embodiment, except that a plurality of light emission-wavelength conversion units emit the first mixed light 14 instead of one light emission-wavelength conversion unit emitting the first mixed light 14. Therefore, a description of the operation of the light emitting device 10B according to the second embodiment will be omitted.

[0193] [Third embodiment] The light emitting device 10C according to the third embodiment shown in Fig. 3 includes a solid-state light emitting element 3, a first wavelength converter 1A, and a second wavelength converter 2A. Specifically, the light emitting device 10C according to the third embodiment is an example of a light emitting device configured to use only a plurality of solid-state light emitting elements 3. In the light emitting device 10C, the plurality of solid-state light emitting elements 3 are aligned and arranged so that the distance between each solid-state light emitting element 3 and the first wavelength converter 1A is constant. Note that, although the plurality of solid-state light emitting elements 3 and the first wavelength converter 1A are spaced apart in the light emitting device 10C, they may also be structured to be in close contact with each other.

[0194] The light emitting device 10C according to the third embodiment is the same as the light emitting device 10A according to the first embodiment, except that a plurality of solid-state light emitting elements 3 are used, and are aligned so that the distance between each solid-state light emitting element 3 and the first wavelength converter 1A is constant. For this reason, the same members in the light emitting device 10C according to the third embodiment and the light emitting device 10A according to the first embodiment are denoted by the same reference numerals, and descriptions of these members will be omitted.

[0195] (Operation of the light emitting device) In the operation of the light emitting device 10A according to the first embodiment, the primary light 3B emitted from one solid-state light emitting element 3 is received by one first wavelength converter 1A. On the other hand, in the operation of the light emitting device 10C according to the third embodiment, the primary light 3B emitted from a plurality of solid-state light emitting elements 3 is received by one first wavelength converter 1A.

[0196] The operation of the light emitting device 10C according to the third embodiment is the same as that of the light emitting device 10A according to the first embodiment, except that the primary light 3B received by one first wavelength converter 1A is a plurality of primary lights 3B emitted by a plurality of solid-state light emitting elements 3. Therefore, a description of the operation of the light emitting device 10C according to the third embodiment will be omitted.

[0197] (Basic configuration example of a light emitting device) 1 to 3, blue light emitted by a solid-state light-emitting element (such as a light-emitting diode or a laser diode) can be used as primary light 3B. Hereinafter, light-emitting devices 10A to 10C shown in FIGS. 1 to 3 will also be referred to simply as "light-emitting device 10."

[0198] In the light emitting device 10, for example, visible light from the first phosphor 1 that absorbs blue light and converts it into visible light with a longer wavelength than the blue light can be used as the first wavelength converted light 1B.

[0199] In the light emitting device 10, for example, near-infrared light produced by the second phosphor 2 that absorbs blue light and converts it into near-infrared light can be used as the second wavelength-converted light 2B.

[0200] In the light emitting device 10, for example, the solid-state light emitting element 3 may be a solid-state light emitting element that emits blue light having a fluorescence peak in a wavelength range of 430 nm or more and less than 480 nm, preferably 440 nm or more and less than 470 nm, as primary light 3B.

[0201] In the light emitting device 10, for example, a phosphor that absorbs blue light and converts it into green light or red light that becomes the first wavelength converted light 1B can be used as the first phosphor 1. Examples of such phosphors include Ce 3+ or EU 2+ A phosphor activated with Ce, preferably Ce 3+ Activated garnet phosphor and / or Eu 2+ Activated nitride phosphors are used.

[0202] In the light emitting device 10, for example, a phosphor that absorbs blue light and / or red light and converts it into near-infrared light that becomes the second wavelength-converted light 2B can be used as the second phosphor 2. Examples of such phosphors include phosphors activated with transition metal ions, preferably Cr 3+ An activated garnet phosphor can be used.

[0203] With this configuration, the output light 4, which is composed of the first light component 5, the second light component 6, and the third light component 7, has both visible and near-infrared light components, as shown in Fig. 4. Moreover, the output light 4 has a spectral distribution in which the visible and near-infrared light components are separated with a certain degree of clarity, with the fluorescence intensity being small near the boundaries between them.

[0204] In the light emitting device 10, it is easy to change the color tone of the primary light 3B, which is the origin of the first light component 5, by changing the types of the solid-state light emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A.

[0205] In the light emitting device 10, it is easy to change the color tone of the first wavelength converted light 1B, which is the origin of the second light component 6, by changing the types of the solid-state light emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A.

[0206] In the light emitting device 10, it is easy to change the color tone of the second wavelength converted light 2B, which is the origin of the third light component 7, by changing the types of the solid-state light emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A.

[0207] In the light emitting device 10, the output ratio between the first wavelength converter 1A and the second wavelength converter 2A can be easily changed by changing the thickness of the first wavelength converter 1A and the second wavelength converter 2A or the concentration of the phosphor. Therefore, with this configuration, the spectral distribution of the output light 4 can be easily controlled.

[0208] The light emitting devices 10A to 10C shown in Figures 1 to 3 are examples of a transmissive configuration, in which a first wavelength converter 1A receives primary light 3B on its front surface 1Aa and emits fluorescence from its back surface 1Ab, and a second wavelength converter 2A receives primary light 3B and first converted wavelength light 1B on its front surface 2Aa and emits fluorescence from its back surface 2Ab.

[0209] In such a transmission type configuration, the second mixed light 24, which is a mixed light component of the first light component 5, the second light component 6, and the third light component 7, can be easily output from the same output surface of the second wavelength converter 2A as the output light 4. Therefore, with this transmission type configuration, a light emitting device 10 suitable for miniaturizing the light output surface can be obtained.

[0210] In the light emitting device 10, the primary light 3B emitted by the solid-state light emitting element 3 irradiates the first wavelength converter 1A, and the first transmitted primary light 3BT1 transmitted through the first wavelength converter 1A irradiates the wavelength converter of the second wavelength converter 2A.

[0211] In the light emitting device 10 having a transmissive configuration, both the first wavelength conversion body 1A and the second wavelength conversion body 2A have optical transparency. That is, in the light emitting device 10, the primary light 3B and the first wavelength-converted light 1B transmit through the first wavelength conversion body 1A, and the first transmitted primary light 3BT1 and the transmitted first wavelength-converted light 1BT2 transmit through the second wavelength conversion body 2A. In the light emitting device 10, the second wavelength conversion body 2A emits, as the output light 4, a second mixed light 24 which is a mixed light of the second transmitted primary light 3BT2, the transmitted first wavelength-converted light 1BT2, and the second wavelength-converted light 2B.

[0212] With such a configuration, it is easy to design the device so that the light exit surface that emits the output light 4 falls within the range of the horizontal projection diagram of the first wavelength converter 1A or the second wavelength converter 2A, whichever has the larger area, thereby obtaining a light emitting device 10 that is suitable for miniaturization.

[0213] In the light emitting device 10, the gap between the first wavelength converter 1A and the second wavelength converter 2A is preferably large. The gap between the first wavelength converter 1A and the second wavelength converter 2A is, for example, more than 1 mm, preferably more than 3 mm, and more preferably more than 10 mm. However, from the viewpoint of miniaturization of the light emitting device 10, the gap between the first wavelength converter 1A and the second wavelength converter 2A is, for example, less than 10 cm, preferably less than 3 cm.

[0214] With this configuration, the directional primary light 3B is scattered by the first wavelength converter 1A, and the light diffused by the distance is irradiated onto the second wavelength converter 2A. This makes it possible to obtain a light emitting device 10 that is suitable for achieving both a high homogeneous output of near-infrared light components and a large light output surface.

[0215] In the light emitting device 10, the first wavelength converter 1A is preferably thick. The thickness of the first wavelength converter 1A is, for example, more than 100 μm, preferably more than 300 μm. The thickness of the first wavelength converter 1A may be thicker than the thickness of the second wavelength converter 2A. However, from the viewpoint of miniaturization of the light emitting device 10, the thickness of the first wavelength converter 1A is, for example, less than 3 mm, preferably less than 1 mm.

[0216] With this configuration, the directional primary light 3B is easily scattered by the first wavelength converter 1A, and the scattered light is irradiated onto the second wavelength converter 2A. This makes it possible to obtain a light emitting device 10 that is suitable for achieving both a high homogeneous output of near-infrared light components and a large light output surface.

[0217] (Example of an improved light emitting device) An example of improvements for improving the performance of this embodiment will be described below.

[0218] In the light emitting device 10, the absolute number of photons constituting the output light 4 can be easily increased by using a high-output solid-state light emitting element 3 or by increasing the number of light emitting elements.

[0219] Examples of such light emitting devices 10 include light emitting devices 10 in which the optical energy of the optical component of the output light 4 having a wavelength of 700 nm or more usually exceeds 3 W, preferably exceeds 10 W, and more preferably exceeds 30 W.

[0220] With this configuration, it is possible to obtain light-emitting device 10 that can irradiate an object with relatively strong near-infrared rays even if the object is far away from the object, since it can irradiate the object with strong near-infrared rays. With this configuration, it is possible to obtain light-emitting device 10 that can easily obtain information related to the object, even if the object to be illuminated is very small or has a certain thickness.

[0221] The light emitting device 10 can increase the photon density supplied to the phosphor contained in the wavelength converter by using the solid-state light emitting element 3 as a light emitting element that emits primary light with high light density, such as a laser diode, or by concentrating the light emitted by the light emitting element using an optical lens.

[0222] With this configuration, the light energy density of the primary light 3B irradiating the first wavelength converter 1A is typically 0.3 W / mm 2 , preferably 1.0 W / mm 2 , more preferably 3.0 W / mm 2 Thus, a light emitting device 10 exceeding the above value can be obtained.

[0223] With such a configuration, a light emitting device 10 capable of emitting output light 4 with high optical energy density can be obtained, and therefore, for example, a light emitting device 10 capable of point outputting near-infrared light with high optical energy density can be obtained.

[0224] In addition, if a light emitting element that emits primary light with high optical density, such as a laser diode, is used, the optical energy density of the primary light emitted by the solid-state light emitting element 3 can be increased. 2 , preferably 1.0 W / mm 2 , more preferably 3.0 W / mm 2 Thus, a light emitting device 10 exceeding the above value can be obtained.

[0225] For this reason, with this configuration, even if the first wavelength converter 1A is irradiated with diffused primary light, a light emitting device 10 that emits a relatively strong near-infrared light component can be obtained. With the configuration, the first wavelength converter 1A is directly irradiated with non-diffused primary light, a light emitting device 10 that emits output light 4 with a relatively high light energy density can be obtained. With this configuration, a light emitting device 10 that can irradiate a large area with near-infrared light using a light emitting element with a small light output surface can be obtained. Furthermore, with the above configuration, a light emitting device 10 that is suitable for irradiating near-infrared light with a high light energy density can be obtained.

[0226] In the light emitting device 10, the output light 4 can be adjusted by selecting an appropriate solid-state light emitting element. For example, by selecting an appropriate solid-state light emitting element, a light emitting device 10 can be obtained in which the intensity of the light component in the ultraviolet to blue wavelength region with a wavelength shorter than 440 nm is less than 3%, preferably less than 1%, of the maximum fluorescent intensity.

[0227] With this configuration, the output light 4 has an intensity close to zero for the light components in the ultraviolet to blue wavelength region to which photoresist is easily exposed. This results in a light emitting device 10 that emits near-infrared light suitable for semiconductor-related inspection work, for example, suitable for use in a yellow room.

[0228] The light emitting device 10 may include, for example, a light distribution control mechanism for controlling light distribution characteristics. With such a configuration, the light emitting device 10 is suitable for obtaining output light having desired light distribution characteristics, such as an in-vehicle variable light distribution lighting system.

[0229] The light emitting device 10 may be provided with an output intensity variable mechanism for changing the intensity of near-infrared rays, such as a control device for input power, etc. With such a configuration, the light emitting device 10 is suitable for testing foods, medicines, etc. that are easily damaged by near-infrared irradiation.

[0230] Furthermore, the light-emitting device 10 may be provided with a control mechanism for controlling, in particular, ON-OFF control of, the output ratio of the light component of the second wavelength-converted light 2B. With such a configuration, the output ratio of near-infrared light can be controlled, thereby providing a light-emitting device 10 suitable for adjusting the intensity of the output near-infrared light according to customer needs.

[0231] Furthermore, the light emitting device 10 may alternately output the output light 4 containing the optical component of the second wavelength converted light 2B and the output light 4 not containing the optical component. With such a configuration, a light emitting device 10 is obtained that can confirm the appearance by alternating between the appearance by the human eye and the appearance by the eye (sensor) of the electronic device. This makes it possible to eliminate interference between the appearance by the human eye and the appearance by the eye of the electronic device, and obtains a light emitting device 10 that is suitable for making the appearance clear regardless of which eye is used.

[0232] The light emitting device 10 may be provided with, for example, a variable mechanism for changing the fluorescence peak wavelength of a light component having a maximum fluorescence intensity within a wavelength range of 700 nm or more and less than 2500 nm.

[0233] With this configuration, it is possible to obtain a light emitting device 10 that is highly versatile and can be easily used for various applications. In addition, since the penetration depth of light into an irradiated object varies depending on the wavelength, it is possible to obtain a light emitting device 10 that is suitable for inspecting an irradiated object in the depth direction.

[0234] Such a near-infrared control mechanism and a fluorescence peak wavelength variable mechanism can be realized by, for example, making the light emitting device 10 equipped with an optical filter such as a band-pass filter or a low-cut filter. In this case, the structure may be one in which the output light 4 passes through an optical filter selected according to the application and is output, or one in which the output light 4 is blocked by the selected optical filter.

[0235] The light emitting device 10 may be provided with a light control mechanism that controls, including ON-OFF control, the output of at least a portion of the wavelength components of the output light 4, not limited to the near-infrared light components. Even with such a configuration, a light emitting device 10 that is highly versatile and can be easily used for various purposes can be obtained.

[0236] The light emitting device 10 can output the output light 4 as pulsed light.

[0237] An example of the half-width of the irradiation time of the pulsed light is less than 300 ms, and the greater the output intensity of the output light 4 or the third light component 7 (near-infrared light component), the shorter the half-width can be. An appropriate half-width selected from, for example, less than 100 ms, less than 30 ms, less than 10 ms, less than 3 ms, and less than 1 ms can be selected according to the output intensity.

[0238] Moreover, an example of the extinguishing time of the pulsed light is not less than 1 ms and less than 10 seconds.

[0239] It has been reported that human eyes perceive light of 50 to 100 Hz (period 20 to 10 ms) as flickering, birds such as pigeons perceive light of 150 Hz (period 6.7 ms), and insects such as flies perceive light of about 300 Hz (period 3.3 ms) as flickering. Therefore, if the extinction time of the pulsed light is 1 ms or more and less than 10 seconds, a preferable light-emitting device 10 with an extinction time of less than 30 ms, in which these creatures including humans do not perceive flickering, can be obtained.

[0240] On the other hand, strong light irradiation has a risk of damaging the illuminated object. For this reason, in applications where flicker is not a concern, it is preferable to use light-emitting device 10 with a pulsed light extinguishing time of 100 ms or more, preferably 300 ms or more.

[0241] The light energy of the output light 4 that is preferable for the purpose of beauty treatment to regulate the growth of human hair or body hair is 0.01 J / cm 2 More than 1J / cm 2It is said that when this level of light energy is applied near the hair root, the light can be absorbed by melanin present in the skin, and the growth of hair, etc. can be regulated. With lower energies than this, it becomes difficult to confirm the effect of regulating the growth of hair, etc. by light irradiation, and with higher energies, concerns arise about other effects on the human body, etc.

[0242] In order to eliminate such concerns, the preferred 1 / 10 decay time of the output light 4 (the time it takes for the light intensity to decrease to 1 / 10 of the intensity immediately before turning off) is less than 100 μs, preferably less than 10 μs, and particularly less than 1 μs. This allows the light-emitting device 10 to be instantly turned on and off.

[0243] The light emitting device 10 may further include an ultraviolet light source that emits ultraviolet light having a maximum intensity within a wavelength range of 120 nm or more and less than 380 nm, preferably 250 nm or more and less than 370 nm. With such a configuration, the light emitting device 10 can also have a sterilizing effect by ultraviolet light.

[0244] The light emitting device 10 may further include a conventionally known general lighting device. With such a configuration, the light emitting device 10 becomes an orthodox lighting device with a function of outputting near-infrared light, and the main function of the light emitting device 10 is general lighting. A representative example of a conventionally known general lighting device is a lighting device that combines a solid-state light emitting element and a phosphor. Specifically, a blue LED and Ce as a green or yellow phosphor are used. 3+ A lighting device that combines an activated garnet phosphor with Eu as a red phosphor. 2+ Activated nitride phosphor or Eu 2+ An example is a lighting device using an activated oxynitride phosphor.

[0245] The light emitting device 10 emitting a near-infrared light component can be a light source or lighting device for medical or biotechnology applications. The light emitting device 10 emitting a near-infrared light component can be a medical light emitting device preferably used for either a fluorescence imaging method or a photodynamic therapy. The light emitting device 10 emitting a near-infrared light component can be a biotechnology light emitting device preferably used for testing, analyzing, or the like of cells, genes, specimens, or the like.

[0246] According to the light emitting device 10 that emits near-infrared light components, the near-infrared light components have the property of penetrating living organisms, cells, etc., and thus the light emitting device 10 can be obtained that can be used for observing or treating diseased areas from inside or outside the body, or for biotechnology.

[0247] The light emitting device 10 that emits a near-infrared light component can be a light source for a sensing system or an illumination system for a sensing system.

[0248] With such a configuration, for example, a light emitting device 10 can be obtained that can be used for inspection in an unopened state, or for monitoring animals and plants including humans and irradiated objects, by using near-infrared light components that have the property of penetrating organic matter and invisible near-infrared light components that are reflected by objects. Here, inspection in an unopened state means inspection of irradiated objects and foreign objects in bags, containers, etc. made of organic materials that do not transmit light, in an unopened state.

[0249] <Electronic equipment> [Fourth to Tenth Embodiments] 5 is a conceptual diagram showing an electronic device according to embodiment 4. The electronic device 200D (200) according to embodiment 1 shown in FIG.

[0250] 5, light emitting device 10 includes at least power supply circuit 111, conductor 112, and light emitting section 113. Light emitting section 113 corresponds to light emitting devices 10A to 10C shown in FIGS. 1 to 3. Components corresponding to power supply circuit 111, conductor 112, etc. in FIG. 5 are omitted in FIGS. 1 to 3. Light emitting device 10 shown in FIG. 5 includes power supply circuit 111 and conductor 112 in addition to light emitting section 113 corresponding to light emitting devices 10A to 10C shown in FIGS. 1 to 3.

[0251] The power supply circuit 111 is a member that supplies power to the light-emitting unit 113 , and supplies electrical energy to the light-emitting unit 113 through a conductor 112 .

[0252] Light-emitting unit 113 is a member that converts electrical energy into light energy, and converts at least a portion of the electrical energy supplied from a power supply circuit into light energy including near-infrared light, and outputs it as output light 4. As described above, light-emitting unit 113 corresponds to light-emitting devices 10A to 10C shown in FIGS.

[0253] The first detector 117A (117) is a member that detects at least a transmitted light component 115 of near-infrared light in the output light 4 that is emitted from the light emitting section 113 of the light emitting device 10 and irradiated onto the object to be irradiated 114.

[0254] The second detector 117B (117) is a member that detects light components including at least a reflected light component 116 of near-infrared light in the output light 4 that is emitted from the light-emitting portion 113 of the light-emitting device 10 and irradiated onto the object to be irradiated 114.

[0255] In the electronic device 200D having the above configuration, first, the output light 4 including at least a near-infrared light component is irradiated onto the irradiated object 114. Next, in the electronic device 200D, either the transmitted light component 115 transmitted through the irradiated object 114 or the reflected light component 116 reflected by the irradiated object 114 is detected by either the first detector 117A or the second detector 117B. Therefore, according to the electronic device 200D, it is possible to detect or sense characteristic information related to the irradiated object 114 involving the near-infrared light component.

[0256] The electronic device 200D includes the light emitting device 10 as described above.

[0257] As described above, the light emitting device 10 achieves both high output of near-infrared light components and a large light output surface area, and emits output light 4 that contains visible light and near-infrared light components and is suitable for both the human eye and a detector. Therefore, by using the light emitting device 10, an electronic device 200D suitable for industrial applications and the like can be obtained, which is used in combination with a near-infrared detector.

[0258] The light emitting device 10 can emit a large amount of output light 4 and illuminate a wide range. With the electronic device 200D configured in this way, even if the irradiated object 114 is irradiated from a long distance, a signal with a good S / N ratio can be detected. With this configuration, the electronic device 200D can be obtained that is suitable for inspecting a large irradiated object 114, inspecting irradiated objects distributed over a wide area, detecting irradiated objects that exist in a part of an inspection area that covers a wide area, detecting people or irradiated objects from a long distance, etc.

[0259] The area of ​​the main light extraction surface of the light-emitting section 113 constituting the light-emitting device 10 is, for example, 1 cm 2 More than 1m 2 Less than 10cm, preferably 2 More than 1000cm 2 is less than.

[0260] The shortest distance from the surface of the light emitting unit 113 to the surface of the irradiated object 114 is, for example, 1 mm or more and less than 10 m. In addition, in applications requiring strong near-infrared light to be irradiated to the irradiated object 114 (for example, medical, cosmetic, delicate foreign body inspection, etc.), the shortest distance is, for example, 1 mm or more and less than 30 cm, particularly 3 mm or more and less than 10 cm. In addition, in applications requiring inspection of a wide range of the irradiated object 114, the shortest distance is, for example, 30 cm or more and less than 10 m, preferably 1 m or more and less than 5 m.

[0261] In addition, in applications requiring strong near-infrared radiation over a wide range (e.g., delicate inspection of a large irradiated object or an irradiated object over a wide range), it is preferable that at least the light-emitting unit 113 is a movable structure. With such a configuration, electronic device 200D is obtained that is preferably structured to be freely movable depending on the shape of the irradiated object to be illuminated. As a more specific embodiment of electronic device 200D, electronic device 200J (200) shown in FIG. 11 and the like can be given.

[0262] Examples of the electronic device 200D having a movable structure include an electronic device 200D having a structure in which the light-emitting unit 113 can move in a straight line or a curve, and an electronic device 200D having a structure in which the light-emitting unit 113 can scan in the XY axis direction or the XYZ direction. Examples of the electronic device 200D having a movable structure include an electronic device 200D attached to a moving body (an automobile, a bicycle, an aircraft such as a drone, etc.). FIG. 11 shows an electronic device 200J in which the electronic device 200D is in the form of a drone.

[0263] Here, various types of photodetectors can be used as the first detector 117A and the second detector 117B. For example, the first detector 117A and the second detector 117B are appropriately selected from quantum-type photodetectors (photodiodes, phototransistors, photo ICs, CCD image sensors, CMOS image sensors, etc.) that detect charges generated when light is incident on a PN junction of a semiconductor, thermal-type photodetectors (thermopiles using the thermoelectric effect, pyroelectric elements using the pyroelectric effect, etc.) that detect changes in electrical properties caused by a rise in temperature due to heat generated when light is received, and infrared films that are sensitive to light.

[0264] The first detector 117A and the second detector 117B may be used as a single element using a single photoelectric conversion element, or may be used as an imaging element integrating photoelectric conversion elements. The imaging element may be a linear type arranged one-dimensionally, or a surface type arranged two-dimensionally. For example, an imaging camera (including a hyperspectral camera) may be used as the first detector 117A and the second detector 117B.

[0265] The electronic device 200D can be used as any one of an inspection device, a detection device, a monitoring device, and a classification device for the irradiated object 114 using the output light 4 including a near-infrared light component.

[0266] Since the near-infrared light component of the output light 4 has the property of transmitting through most substances, it is possible to configure the device so that near-infrared light is irradiated from the outside of the substance and the transmitted or reflected light is detected. This makes it possible to obtain an electronic device 200D that can inspect or detect the internal state of the substance and the presence or absence of foreign matter without destroying the substance. A specific example of the electronic device 200D suitable for such an application is shown as electronic device 200E in FIG. 6. That is, FIG. 6 is a diagram showing an example of an electronic device according to the fifth embodiment.

[0267] 6 includes a belt conveyor 105 on which an irradiated object 114 is placed and moved, a light emitting device 10 that irradiates the irradiated object 114 with irradiated light 120, and a hyperspectral camera 150 that captures an image of an imaging area 130 on the belt conveyor 105. The irradiated light 120 is output light 4 emitted by the light emitting device 10.

[0268] The operation of the electronic device 200E will be briefly described. First, the light emitting device 10 radiates the irradiation light 120 to the irradiation target 114. Next, the hyperspectral camera 150 captures an image of the imaging area 130 on the belt conveyor 105 onto which the irradiation light 120 is radiated, thereby acquiring image data. The acquired image data is used for various purposes such as observation and analysis as it is, or after being processed by a computer (not shown) or the like.

[0269] In addition, the near-infrared light component is invisible to the human eye, and its reflection characteristics depend on the material. Therefore, by configuring the device to irradiate the object with near-infrared light and detect the reflected light, the electronic device 200D can be obtained that can detect or monitor people, animals, plants, irradiated objects, etc., even in the dark without being noticed by people.

[0270] Furthermore, the near-infrared light component can inspect or detect the internal state and the presence or absence of foreign matter without destroying the substance, and can determine the quality of the substance. Therefore, when the near-infrared light component is irradiated onto an irradiated object, electronic device 200D can be obtained that can sort good and bad products. Also, when electronic device 200D is used that further includes a mechanism for removing irradiated object 114 (inspection object) that is detected to be in either a normal state or an abnormal state, electronic device 200D suitable for sorting or separating irradiated objects can be obtained.

[0271] In the electronic device 200D, the light emitting device 10 may be fixed and not movable.

[0272] With this configuration, electronic device 200D that is less likely to break down can be obtained since it does not require a complex mechanism for mechanically moving the light emitting device.

[0273] Furthermore, when the electronic device 200D is fixed indoors or outdoors, it becomes possible to observe the status of people and irradiated objects (scattering objects, moving objects, etc.) at a predetermined location, and to count the number of people and irradiated objects. Therefore, with such a configuration, the electronic device 200D is suitable for collecting big data that is useful for identifying problems and utilizing in business.

[0274] Specific examples of electronic device 200D suitable for such applications are shown as electronic device 200E in FIG. 7, electronic device 200F in FIG. 8, electronic device 200G in FIG. 9, electronic device 200I in FIG. 10, and electronic device 200J in FIG. 11. FIG. 7 is a diagram showing an example of an electronic device according to a sixth embodiment. FIG. 8 is a diagram showing an example of an electronic device according to a seventh embodiment. FIG. 9 is a diagram showing an example of an electronic device according to an eighth embodiment. FIG. 10 is a diagram showing an example of an electronic device according to a ninth embodiment. FIG. 11 is a diagram showing an example of an electronic device according to a tenth embodiment.

[0275] The electronic device 200D may be movable. For example, the electronic device 200D may be movable as a structure attached to a moving stage or a moving body (such as a vehicle or an aircraft). A specific example of the electronic device 200D suitable for such an application is shown as electronic device 200J in FIG.

[0276] With such a configuration, the light-emitting device 10 constituting the electronic device 200D can illuminate a desired location or a wide area, resulting in an electronic device 200D that is suitable for inspecting large irradiated objects or inspecting the condition of irradiated objects outdoors.

[0277] The electronic device 200D can further include a hyperspectral camera. With this configuration, the electronic device 200D capable of hyperspectral imaging is obtained. Such an electronic device 200D can distinguish differences that cannot be distinguished by the naked eye or a normal camera as images, and serves as an inspection device or the like that is useful in a wide range of fields related to product inspection, sorting, and the like.

[0278] It is also preferable that the electronic device 200D is provided with a data processing system that performs machine learning. With such a configuration, not only can the data input to the computer be repeatedly learned and hidden patterns can be found, but newly input data can also be applied to the patterns. Therefore, the electronic device 200D is suitable for automating and improving the accuracy of inspection, detection, and monitoring, and for future predictions using big data.

[0279] The electronic device 200D can be used for any of medical, veterinary, biotechnology, agriculture, forestry, and fisheries, livestock (meat, meat products, dairy products, etc.), and industrial (foreign body inspection, content inspection, shape inspection, packaging condition inspection, etc.) The electronic device 200D can also be used for inspection of any of pharmaceuticals, animal experiments, food, beverages, agricultural, forestry, and fishery products, livestock products, and industrial products.

[0280] The electronic device 200D can be used for any of the human body, animals, plants, and objects, and can be used for any of gases, liquids, and solids.

[0281] The preferred form of the electronic device 200D is any one of a medical device, a treatment device, a beauty device, a health device, a care-related device, an analysis device, a measurement device, and an evaluation device.

[0282] The electronic device 200D used for the purpose of medical and biotechnology development is used, for example, for inspection, detection, measurement, evaluation, analysis, observation, monitoring, separation, diagnosis, treatment, purification, etc. of the irradiated objects listed below. Specifically, examples include inspection of blood / body fluids and their components, inspection of excreta (urine / feces), measurement of protein / amino acids, inspection of cells (including cancer cells), inspection of genes / chromosomes / nucleic acid, inspection of biological samples / bacteria / specimens / antibodies, inspection of biological tissues / organs / blood vessels, observation of skin diseases / alopecia, etc.

[0283] For example, for the purpose of beauty or health care, the electronic device 200D is used for, for example, inspection, detection, measurement, evaluation, analysis, observation, monitoring, beautification, hygiene, growth promotion, health promotion, diagnosis, etc. of the irradiated objects listed below. Specifically, examples include observation of skin, observation of hair and body hair, observation of the mouth, teeth, and periodontium, examination of ears and nose, measurement of vital signs, etc.

[0284] For example, for the purpose of use in agriculture, forestry, fisheries, livestock, or industry, the electronic device 200D is used for, for example, inspection, detection, measurement, gauge, evaluation, analysis, analysis, observation, monitoring, recognition, selection, and separation of the irradiated objects listed below. Specifically, the following can be mentioned: inspection of industrial products (including electronic materials and electronic devices), inspection of agricultural products (fruit and vegetables, etc.), detection of enzymes and bacteria, inspection of marine products (fish, shellfish, crustaceans, and mollusks), inspection of medicines and biological samples, inspection of food and beverages, observation of the presence and state of humans, animals, and irradiated objects, observation of the state of gas (including water vapor), inspection of liquids, fluids, water, moisture, and humidity, observation of the shape, color, internal structure, and physical state of irradiated objects, measurement of space, position, and distance, observation of the contamination state of irradiated objects, observation of the state of molecules and particles, observation of industrial waste, etc.

[0285] For example, for the purpose of care, the electronic device 200D is used for, for example, checking excretion, identifying, managing, and monitoring health conditions, and the like.

[0286] In this manner, the electronic device 200D can be used for a variety of purposes, such as inspection, detection, measurement, gauging, evaluation, analysis, interpretation, observation, monitoring, recognition, sorting, and separation.

[0287] It should be noted that this embodiment is applicable to any simple method using the light emitting device 10, such as an inspection method, a detection method, a monitoring method, a classification method, an analysis method, a measurement method, or an evaluation method.

[0288] Although the contents of the present embodiment have been described above, the present embodiment is not limited to the description, and it will be obvious to those skilled in the art that various modifications and improvements are possible. EXAMPLES

[0289] The light emitting device of this embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to these.

[0290] [Example 1] First, a first wavelength converter 1A was produced. A phosphor sheet made of a resin phosphor film containing a phosphor emitting yellow-green light having a fluorescent peak near 540 nm and a phosphor emitting red light having a fluorescent peak near 625 nm was used as the first wavelength converter 1A. Y3Al2(AlO4)3:Ce 3+ (YAG) phosphor (Tokyo Chemical Laboratory, Inc., central particle size D 50 The phosphor that emits red light with a fluorescence peak at around 625 nm was (Sr,Ca)AlSiN3:Eu 2+ (SCASN) Phosphor (Mitsubishi Chemical Corporation, central particle size D 50 ≒14 μm) was used.

[0291] The procedure for producing the first wavelength converter 1A will be described below. The above-mentioned YAG phosphor and SCASN phosphor were prepared as phosphor powders. In addition, a two-part thermosetting silicone resin (product name KER-2500A / B, Shin-Etsu Chemical Co., Ltd.) was prepared as a sealant for the phosphor powders.

[0292] Next, YAG phosphor (0.493g), SCASN phosphor (0.013g), and silicone resin (0.75g of agent A and 0.75g of agent B) were mixed and degassed (approximately 2000rpm, 3 minutes) to prepare a phosphor paste consisting of phosphor and silicone resin. A machine called "Awatori Rentaro" (model: ARE-310, manufactured by Shinki Corporation) was used for the mixing and degassing process.

[0293] The obtained phosphor paste was dropped into a mold provided on a glass substrate (200 mm x 200 mm x t1 mm) using a dispenser (model: ML-5000XII, manufactured by Musashi Engineering Co., Ltd.). The surface of the dropped phosphor paste was then smoothed and flattened using a squeegee. The mold was removed, and the phosphor sheet formed by heating and curing in the atmosphere at 150°C for 2 hours was peeled off from the glass substrate using tweezers to obtain a first wavelength converter 1A. The first wavelength converter 1A had a size of 5 mm x 6 mm and a thickness of 130 μm.

[0294] Just to be sure, the fluorescent properties of the first wavelength converter 1A were evaluated under light excitation conditions of 450 nm using an absolute PL quantum yield measurement device, and the internal quantum efficiency (IQE) was 93%, the light absorptance (Abs.) was 28%, and the fluorescent peak wavelength was 598 nm.

[0295] Next, a second wavelength converter 2A was prepared. The second wavelength converter 2A was made of Cr 3+ The phosphor sheet was a resin phosphor film containing a phosphor mainly composed of a composite metal oxide (our own product) activated with Gd 0.95 La 0.05 )3(Ga 0.97 Cr 0.03 (Gd,La)3Ga2(GaO4)3:Cr, represented by the formula: )2(GaO4)3 3+ (GLGG) phosphor and has a garnet-type crystal structure.

[0296] The procedure for preparing the GLGG phosphor will be described below. The GLGG phosphor was prepared by a conventional solid-state reaction using the following compound powders as the main raw materials. Gadolinium oxide (Gd2O3): 3N purity, Japan Yttrium Co., Ltd. Lanthanum hydroxide (La(OH)3): 3N purity, Shin-Etsu Chemical Co., Ltd. Gallium oxide (Ga2O3): 4N purity, Asia Physical Materials Co., Ltd. Chromium oxide (Cr2O3): 3N purity, manufactured by High Purity Chemical Laboratory Co., Ltd.

[0297] Specifically, first, a compound with a stoichiometric composition (Gd 0.95 La 0.05 )3(Ga 0.97 Cr 0.03 The raw materials were weighed out so as to produce 100% GaO. The weighed values ​​are shown in Table 1.

[0298] [Table 1]

[0299] Next, 20 g of the weighed raw materials were put into an alumina pot mill (volume 250 ml) together with alumina balls (diameter φ3 mm, total 200 g) and 60 ml of ethanol. After that, the raw materials were wet-mixed by rotating the pot mill at a rotation speed of 150 rpm for 30 minutes using a planetary ball mill (manufactured by Fritsch, product number P-5).

[0300] Next, the alumina balls were removed using a sieve to obtain a slurry-like mixed raw material consisting of the raw materials and ethanol. The slurry-like mixed raw material was then completely dried at 125°C using a dryer. The dried mixed raw material was then lightly mixed using a mortar and pestle to obtain a phosphor raw material.

[0301] Next, the phosphor raw material was placed in an alumina firing container (material: SSA-H, B3 size, with lid) and fired in a box-type electric furnace in air at 1500°C for 2 hours. The temperature increase and decrease rate during firing was 300°C / h.

[0302] The obtained fired product was manually crushed using an alumina mortar and pestle, and then passed through a nylon mesh (mesh opening 95 μm) to remove coarse particles, thereby obtaining a powdered GLGG phosphor.

[0303] Although the data is omitted, the crystal composition of the obtained GLGG phosphor was evaluated using an X-ray diffraction device (Desktop X-ray diffraction device, MiniFlex (registered trademark), manufactured by Rigaku Corporation), and was found to be a garnet compound with a nearly single crystal phase. In addition, the particle shape and particle size were evaluated using an electron microscope (Desktop microscope, Miniscope TM4000, manufactured by Hitachi High-Technologies Corporation). As a result, the particle morphology was monodisperse particle-like, the particle shape was a shape that could be considered to be derived from garnet crystals, and the particle size was mainly around 15 μm. The fluorescent properties of the GLGG phosphor were evaluated under irradiation conditions of blue light with a wavelength of 450 nm using an absolute PL quantum yield measurement device (C9920-02, manufactured by Hamamatsu Photonics Co., Ltd.). As a result, the fluorescent peak wavelength was 747 nm, the internal quantum efficiency (IQE) was 92%, and the light absorptance (Abs.) of blue light was 57%. In addition, when evaluated under irradiation with red light with a wavelength of 628 nm, the fluorescence peak wavelength was 746 nm, the internal quantum efficiency (IQE) was 93%, and the light absorptance (Abs.) of red light was 45%.

[0304] Using the GLGG phosphor (4.57 g) prepared in this manner and molds of different thicknesses, a second wavelength converter 2A (10 mm x 10 mm, thickness: 265 μm) was prepared in the same manner as the first wavelength converter 1A.

[0305] Just to be sure, the fluorescent properties of the second wavelength converter 2A were evaluated under light excitation conditions of 450 nm using the above-mentioned absolute PL quantum yield measurement device, and the internal quantum efficiency (IQE) was 90%, the light absorptance (Abs.) was 57%, and the fluorescent peak wavelength was 733 nm.

[0306] Next, a light emitting device was produced using the first wavelength converter 1A and the second wavelength converter 2A produced in this manner.

[0307] Specifically, a first wavelength converter 1A was disposed on the light output surface of a blue LED chip (product number: LE B P2MQ, manufactured by OSRAM Opto Semiconductors) serving as a solid-state light-emitting element 3 emitting primary light 3B that is blue light (fluorescence peak wavelength: 450 nm). A second wavelength converter 2A was disposed on this first wavelength converter 1A to configure a light-emitting device as shown in FIG. 1, which was the light-emitting device according to Example 1.

[0308] When power (10.3 V, 20 mA) was applied to the blue LED chip, blue light was emitted from the blue LED chip as primary light 3B. A part of this was converted by the first wavelength converter 1A into visible light (yellow light resulting from additive color mixing of green and red light components) as first wavelength-converted light 1B. Furthermore, a part of the mixed light of the primary light 3B and the first wavelength-converted light 1B was converted by the second wavelength converter 2A into deep red to near infrared light components as second wavelength-converted light 2B. A mixed light consisting of blue light as the primary light 3B, visible light as the first wavelength-converted light 1B, and light containing a near infrared light component as the second wavelength-converted light 2B was emitted as output light 4.

[0309] 12(a), (b), and (c) show the spectral distributions of the primary light 3B emitted by the blue LED chip, the first mixed light 14, and the output light 4, respectively. The first mixed light 14 is a mixed light component including the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B. The output light 4 is a mixed light component including the second transmitted primary light 3BT2, the transmitted first wavelength-converted light 1BT2, and the second wavelength-converted light 2B. The second transmitted primary light 3BT2 is the first transmitted primary light 3BT1 transmitted through the second wavelength converter 2A. The transmitted first wavelength-converted light 1BT2 is the first wavelength-converted light 1B transmitted through the second wavelength converter 2A.

[0310] As can be seen from FIGS. 12(a), (b) and (c), the primary light 3B was a single-peaked blue light having a fluorescent peak at 455 nm, with a half-width of about 17 nm (not less than 15 nm and less than 20 nm).

[0311] The first mixed light 14, which includes the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B, contains the light components of the primary light 3B and the first wavelength-converted light 1B. The first mixed light 14 had a correlated color temperature of 30243 K, duv=-26.4, (x, y)=(0.271, 0.230), and Ra=81. The light components of the first wavelength-converted light 1B had peaks at 540 nm and 590 nm, and were multi-peaked broad light components having light components over a wide wavelength range from at least 495 nm to 800 nm.

[0312] Output light 4 includes second transmitted primary light 3BT2 derived from primary light 3B, transmitted first wavelength-converted light 1BT2 derived from first wavelength-converted light 1B, and light components of second wavelength-converted light 2B. Output light 4 had a correlated color temperature of 4646 K, duv=24.1, (x, y)=(0.365, 0.421), and Ra=69. The light components of output light 4 had peaks at 455 nm, 545 nm, and 730 nm, and were multi-peaked broad light components having light components over a wide wavelength range of at least 410 nm to 950 nm.

[0313] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0314] [Example 2] The light emitting device according to Example 2 is designed to suppress the output of primary light 3B compared to Example 1, and is intended for use in environments where ultraviolet to blue light is undesirable, such as semiconductor manufacturing lines.

[0315] The first wavelength converter 1A (thickness: 200 μm) was produced in the same manner as in Example 1, except that the amounts of the YAG phosphor and the SCASN phosphor used in Example 1 were 2.852 g and 0.076 g, respectively, and molds with different thicknesses were used. Just to be sure, the fluorescent characteristics of the first wavelength converter 1A were evaluated under optical excitation conditions of 450 nm using the above-mentioned absolute PL quantum yield measurement device, and the internal quantum efficiency (IQE) was 94%, the light absorption rate (Abs.) was 30%, and the fluorescent peak wavelength was 607 nm. In addition, the second wavelength converter 2A and the solid light-emitting element 3 used in Example 1 were reused. Then, in the same manner as in Example 1, the solid light-emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A were arranged to configure a light-emitting device as shown in FIG. 1, which was the light-emitting device according to Example 2.

[0316] As in Example 1, power (10.3 V, 20 mA) was applied to the blue LED chip to light up the light emitting device of Example 2.

[0317] 13(a), (b), and (c) show the spectral distributions of the primary light 3B emitted by the blue LED chip, the first mixed light 14, and the output light 4, respectively. The first mixed light 14 is a mixed light component including the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B. The output light 4 is a mixed light component including the second transmitted primary light 3BT2, the transmitted first wavelength-converted light 1BT2, and the second wavelength-converted light 2B. The second transmitted primary light 3BT2 is the first transmitted primary light 3BT1 transmitted through the second wavelength converter 2A. The transmitted first wavelength-converted light 1BT2 is the first wavelength-converted light 1B transmitted through the second wavelength converter 2A.

[0318] As can be seen from FIGS. 13(a), (b) and (c), the primary light 3B was a single-peaked blue light having a fluorescent peak at 455 nm and a half-width of about 17 nm.

[0319] The first mixed light 14, which includes the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B, contains the primary light 3B and the light components of the first wavelength-converted light 1B. The first mixed light 14 had a correlated color temperature of 2510 K, duv=12.5, (x, y)=(0.501, 0.455), and Ra=77. The light component of the first wavelength-converted light 1B was a single-peaked broad light component that had a peak at 610 nm and light components over a wide wavelength range from at least 495 nm to 800 nm.

[0320] The output light 4 contained the light components of the primary light 3B, the first wavelength-converted light 1B, and the second wavelength-converted light 2B, and had a correlated color temperature of 2828 K, duv=21.6, (x, y)=(0.489, 0.482), and Ra=68. The light components of the output light 4 had peaks at 455 nm, 590 nm, and 715 nm, and were multi-peaked broad light components having light components over a wide wavelength range of at least 410 nm to 950 nm. However, the spectral intensity in the wavelength region less than 500 nm was less than 7% of the maximum spectral intensity of the output light 4 (spectral intensity of the light component with a wavelength of 590 nm), and the intensity of the light components in the ultraviolet to blue wavelength region was greatly suppressed in the output light 4.

[0321] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0322] [Example 3] The light emitting device according to Example 3 is designed such that the minimum value of the maximum spectral intensity in the wavelength range of 520 nm or more and less than 750 nm is 70% or more compared to Example 1. Specifically, it is intended for use as a light source or the like for applications requiring a characteristic in which the amount of change in spectral intensity in the wavelength range from green to deep red is small.

[0323] The first wavelength converter 1A was a phosphor sheet made of a resin phosphor film containing a phosphor that emits green light having a fluorescent peak near 525 nm and a phosphor that emits red light having a fluorescent peak near 655 nm. The phosphor that emits green light having a fluorescent peak near 525 nm was Lu3Al2(AlO4)3:Ce 3+ (LuAG) phosphor (Tokyo Chemical Laboratory, Inc., central particle size D 50 The red light-emitting phosphor with a fluorescence peak at around 655 nm was CaAlSiN3:Eu 2+ (CASN) Phosphor (Mitsubishi Chemical Corporation, central particle size D 50 ≒18 μm) was used.

[0324] The first wavelength converter 1A (thickness: 260 μm) was produced in the same manner as in Example 1, except that the amounts of the LuAG phosphor and the CASN phosphor used were 0.849 g and 0.157 g, respectively, and molds with different thicknesses were used. Just to be sure, the fluorescent properties of the first wavelength converter 1A were evaluated under optical excitation conditions of 450 nm using the above-mentioned absolute PL quantum yield measurement device, and the internal quantum efficiency (IQE) was 93%, the light absorption rate (Abs.) was 32%, and the fluorescent peak wavelength was 630 nm. In addition, the second wavelength converter 2A and the solid light-emitting element 3 used in Example 1 were reused. Then, similarly to Example 1, the solid light-emitting element 3, the first wavelength converter 1A, and the second wavelength converter 2A were arranged to configure a light-emitting device as shown in FIG. 1, which was the light-emitting device according to Example 3.

[0325] As in Example 1, power (10.3 V, 20 mA) was applied to the blue LED chip to light up the light emitting device of Example 3.

[0326] 14(a), (b), and (c) show the spectral distributions of the primary light 3B emitted by the blue LED chip, the first mixed light 14, and the output light 4, respectively. The first mixed light 14 is a mixed light component including the first transmitted primary light 3BT1, which is the primary light 3B transmitted through the first wavelength converter 1A, and the first wavelength-converted light 1B. The output light 4 is a mixed light component including the second transmitted primary light 3BT2, the transmitted first wavelength-converted light 1BT2, and the second wavelength-converted light 2B. The second transmitted primary light 3BT2 is the first transmitted primary light 3BT1 transmitted through the second wavelength converter 2A. The transmitted first wavelength-converted light 1BT2 is the first wavelength-converted light 1B transmitted through the second wavelength converter 2A.

[0327] As can be seen from FIGS. 14(a), (b) and (c), the primary light 3B was a single-peaked blue light having a fluorescent peak at 455 nm and a half-width of about 17 nm.

[0328] The first mixed light 14, which includes the primary light 3B and the first wavelength-converted light 1B transmitted through the first wavelength converter 1A, contains the light components of the primary light 3B and the first wavelength-converted light 1B. The first mixed light 14 had a correlated color temperature of 4146 K, duv=-3.0, (x, y)=(0.372, 0.365), and Ra=93. The light components of the first wavelength-converted light 1B had peaks at 555 nm and 635 nm, and were multi-peaked broad light components having light components over a wide wavelength range from at least 495 nm to 800 nm.

[0329] The output light 4 includes the second transmitted primary light 3BT2 derived from the primary light 3B, the transmitted first wavelength-converted light 1BT2 derived from the first wavelength-converted light 1B, and the light components of the second wavelength-converted light 2B. The output light 4 was a high color rendering light with a correlated color temperature of 3893K, duv=25.1, (x, y)=(0.407, 0.453), and Ra=83. The light components of the output light 4 had peaks at 460 nm, 550 nm, 655 nm, and 715 nm, and were multi-peaked broad light components having light components over a wide wavelength range of at least 410 nm to 950 nm. The spectral intensity in the wavelength range of 520 nm or more and less than 750 nm was maximum at 715 nm, and the spectral intensity at 595 nm, which was the minimum, was 73.8% of that.

[0330] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0331] Here, we focus on the duv of the first mixed light 14 and the output light 4. duv is an index that indicates the deviation from blackbody radiation and indicates the color tone of white light. If the duv value is positive, the white light has a greenish tone, and if it is negative, the white light has a purplish tone.

[0332] As can be seen from the explanations of Examples 1 to 3, the value of duv swings significantly to the positive side when the first mixed light 14 is converted into the output light 4 by the second wavelength converter 2A. The swing range is 5 or more and less than 55. This is due to the Cr content of the second wavelength converter 2A. 3+ This is because the first mixed light 14 has the property of absorbing the blue and red light components well and not absorbing the green light component very much.

[0333] That is, the blue and red light components of the first mixed light 14 are likely to be absorbed by the second wavelength converter 2A and converted into near-infrared light components. In contrast, the green light component of the first mixed light 14 is likely to be transmitted through the second wavelength converter 2A without being absorbed by the second wavelength converter 2A. For this reason, compared to the white light of the first mixed light 14, the output light 4 becomes greenish white light.

[0334] For this reason, it is preferable that the duv value of the first mixed light 14 is negative, and the preferable range of the duv value is from -55 to less than -5, and particularly from -50 to less than -10. This makes it easy to output white light (duv=0±2) with a color tone close to that of natural light.

[0335] [Examples 4 to 6] As the light emitting devices of Examples 4 to 6, a light emitting device was prepared by combining a white LED for LED lighting, which is a combination of a blue LED (peak fluorescence wavelength: 455 nm) and a red LED (peak fluorescence wavelength: 633 nm) phosphor, and a second wavelength converter 2A. The second wavelength converter 2A was simply placed on the light output surface of the obtained white LED (2700K, manufactured by Lumileds LLC), and the white LED was turned on by passing a rated current (136 mA). The output light was integrated with an integrating sphere (φ20 inches, product number: LMS-200, manufactured by Labsphere), and the spectral distribution and radiant flux of the output light 4 were measured using a total luminous flux measuring system (SLMS-CDS-2021, manufactured by Labsphere).

[0336] Here, the second wavelength converter 2A used was a wavelength converter obtained by changing the thickness of the second wavelength converter (a resin phosphor film using a GLGG phosphor) used in Example 1 to three different thicknesses (155 μm, 240 μm, and 340 μm). The three wavelength converters with different thicknesses were produced using molds with different thicknesses.

[0337] Fig. 15 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 4 to 6. (a), (b), and (c) in Fig. 15 correspond to the output light 4 of Examples 4, 5, and 6, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm, and 340 μm, respectively. (d) in Fig. 15 shows the spectral distribution (Reference Example 1) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0338] As can be seen from Figures 15(a), (b) and (c), the spectral distribution of the output light 4 includes light components in the entire wavelength range of at least 420 nm to less than 950 nm. The spectral distribution of the output light 4 includes a fluorescent component derived from the blue LED and a fluorescent component derived from the green phosphor (Ce 3+ The fluorescent components derived from the red LED and the near-infrared phosphor (Cr 3+ The fluorescent components derived from the blue LED had a peak at around 450 nm. The fluorescent components derived from the green phosphor (Ce 3+ The fluorescent component derived from the near-infrared phosphor (Cr doped garnet phosphor) has a peak or shoulder-like bulge at around 550 nm. The fluorescent component derived from the red LED has a peak at around 635 nm. 3+ The fluorescent component originating from the activated garnet phosphor had a peak at around 730 nm.

[0339] We focused on the spectral intensities of light components with wavelengths of 450 nm, 550 nm, 635 nm, and 730 nm. In the white LED that does not use the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the 635 nm spectral intensity derived from the red LED. The next strongest spectral intensities (heights) were the 550 nm spectral intensity derived from the green phosphor and the 450 nm spectral intensity derived from the blue LED.

[0340] In Examples 4 to 6 ((a) to (c) in FIG. 15), which were combined with second wavelength converters 2A of different thicknesses, the spectral intensities at 450 nm, 550 nm, and 635 nm decreased as the thickness of the second wavelength converter 2A increased. In particular, the spectral intensities at 450 nm and 635 nm decreased significantly. As a result, the spectral distributions of Examples 4 to 6 had minimum values ​​in the wavelength range of 560 nm or more and less than 610 nm. On the other hand, the spectral intensity at 730 nm increased as the thickness of the second wavelength converter 2A increased.

[0341] In Examples 4 to 6, the spectral intensity at 730 nm was smaller than that at 635 nm, but larger than that at 550 nm. In Example 6 ((c) in FIG. 15), the spectral intensity at 730 nm was larger than that at 635 nm, and was the strongest among them. In Examples 4 to 6, the spectral intensity at 450 nm was smaller than that at 730 nm, being less than 25% of that, and particularly in Example 6, it was less than 5% of that.

[0342] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 that contains a strong red light component, a strong near-infrared component, and a weaker green light component in comparison, with a suppressed intensity of the blue light component.

[0343] Table 2 summarizes the characteristics as illumination light of the output light 4 of Examples 4 to 6. For comparison, the table also shows the characteristics of Reference Example 1 (a white LED not provided with the second wavelength converter 2A).

[0344] [Table 2]

[0345] As can be seen from Table 2, the radiant flux and luminous flux tended to decrease as the thickness of the second wavelength converter 2A increased, i.e., from Example 4 to Example 5 and then to Example 6. On the other hand, the correlated color temperature tended to increase slightly, and the average color rendering index (Ra) showed a tendency to increase significantly in the numerical range of 80 or more indicating high color rendering, exceeding 90, and then gradually decreasing.

[0346] From these data, it can be said that this embodiment is a suitable light emitting device for obtaining output light 4 that has both high output near infrared radiation and high color rendering properties.

[0347] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0348] [Examples 7 to 9] As the light-emitting devices of Examples 7 to 9, light-emitting devices were produced by combining a white LED for LED lighting, which was a combination of a blue LED and a red LED with a phosphor, and a second wavelength converter 2A. In the same manner as in Examples 4 to 6, the second wavelength converter 2A was placed on the light output surface of a white LED (3500K, manufactured by Lumileds LLC) obtained, and the spectral distribution and radiant flux of the output light 4 output by passing a rated current (136 mA) through the white LED were measured.

[0349] Fig. 16 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 7 to 9. (a), (b), and (c) in Fig. 16 correspond to the output light 4 of Examples 7, 8, and 9, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm, and 340 μm, respectively. (d) in Fig. 16 shows the spectral distribution (Reference Example 2) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0350] As can be seen from Figs. 16(a), (b) and (c), the spectral distributions of the output light 4 in Figs. 16(a), (b) and (c) are the same as those in Examples 4 to 6 described above with reference to Fig. 15. Therefore, as in Fig. 15, attention was paid to the spectral intensities of the light components with wavelengths of 450 nm, 550 nm, 635 nm and 730 nm. In the white LED not using the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the spectral intensity of 635 nm originating from the red LED. The spectral intensity of 450 nm originating from the blue LED and the spectral intensity of 550 nm originating from the green phosphor showed the next highest spectral intensity (height).

[0351] Even in the present Examples 7 to 9 (a to (c) in Figure 16), which were combined with second wavelength converters 2A of different thicknesses, the basic behavior of the optical spectrum observed as the thickness of the second wavelength converter 2A increased was similar to that in the previous Examples 4 to 6.

[0352] In Examples 7 to 9, the spectral intensity at 730 nm was smaller than the spectral intensity at 550 nm and 635 nm in Examples 7 and 8 in which the thickness of the second wavelength converter 2A was at least 240 nm or less. However, in Example 9 in which the thickness was at least 340 nm or more, the spectral intensity was approximately the same as that at 550 nm and 635 nm, and the spectral intensity difference between 550 nm, 635 nm, and 730 nm was ±10%. Moreover, the spectral intensity at 730 nm was at least greater than the spectral intensity at 635 nm. In Examples 7 to 9, the spectral intensity at 450 nm was smaller than the spectral intensity at 730 nm, and was less than 65% of the spectral intensity. In particular, in Example 9, the spectral intensity was less than 15%.

[0353] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 that contains a strong green light component, a strong red light component, and a strong near-infrared component, with the intensity of the blue light component suppressed.

[0354] The characteristics as illumination light of the output light 4 of Examples 7 to 9 are summarized in Table 3. For comparison, the characteristics of Reference Example 2 (a white LED not provided with the second wavelength converter 2A) are also shown in the same table.

[0355] [Table 3]

[0356] As can be seen from Table 3, as the thickness of the second wavelength converter 2A increased, that is, from Example 7 to Example 8 to Example 9, the radiant flux, luminous flux and general color rendering index (Ra) tended to decrease. On the other hand, the correlated color temperature tended to increase slightly. However, in comparison with the case where a second wavelength converter 2A of the same thickness was used, the radiant flux and luminous flux were at a level 20% or more higher than those of Examples 4 to 6. In particular, the luminous flux was at a level 70% or more higher.

[0357] From these data, it can be said that this embodiment is a suitable light emitting device for obtaining output light 4 that combines high-power near-infrared radiation and high luminous flux.

[0358] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0359] [Examples 10 to 12] As the light-emitting devices of Examples 10 to 12, light-emitting devices were produced by combining a white LED for LED lighting, which was a combination of a blue LED and a phosphor, with a second wavelength converter 2A. In the same manner as in Examples 4 to 6, the second wavelength converter 2A was placed on the light output surface of a white LED (5000K, manufactured by Citizen Electronics Co., Ltd.) obtained, and the spectral distribution and radiant flux of the output light 4 output by passing a rated current (269 mA) through the white LED were measured.

[0360] Fig. 17 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 10 to 12. (a), (b), and (c) in Fig. 17 correspond to the output light 4 of Examples 10, 11, and 12, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm, and 340 μm, respectively. (d) in Fig. 17 shows the spectral distribution (Reference Example 3) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0361] As can be seen from Figures 17(a), (b) and (c), the spectral distribution of the output light 4 includes light components in the entire wavelength range of at least 420 nm to less than 950 nm. The spectral distribution of the output light 4 includes a fluorescent component derived from the blue LED, a fluorescent component derived from the mixed fluorescent component of the green phosphor and the red phosphor, and a fluorescent component derived from the near-infrared phosphor (Cr 3+ The fluorescent component derived from the mixed fluorescent components of the green and red phosphors was mainly derived from the green phosphor (Ce 3+ activated garnet phosphor) and red phosphor (Eu 2+ The fluorescent component derived from the blue LED had a peak at around 450 nm. 3+ activated garnet phosphor) and red phosphor (Eu 2+The fluorescent component derived from the mixed fluorescent components of the near-infrared phosphor (Cr 3+ The fluorescent component originating from the activated garnet phosphor had a peak at around 730 nm.

[0362] Therefore, we focused on the spectral intensity of the light components with wavelengths of 450 nm, 560 nm, and 730 nm. In the white LED that did not use the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the spectral intensity of 450 nm originating from the blue LED. The next strongest spectral intensity (height) was the spectral intensity of 560 nm originating from both the green phosphor and the red phosphor.

[0363] In Examples 10 to 12 ((a) to (c) in Figure 17), which were combined with second wavelength converters 2A of different thicknesses, the spectral intensity at 450 nm and 560 nm, especially at 450 nm, decreased significantly as the thickness of the second wavelength converter 2A increased. As a result, the spectral distributions of Examples 10 to 12 had a maximum value in the wavelength range of 550 nm or more and less than 580 nm. On the other hand, as the thickness of the second wavelength converter 2A increased, the spectral intensity at 730 nm increased and had a minimum value in the wavelength range of 600 nm or more and less than 700 nm.

[0364] In Examples 10 to 12, the spectral intensity at 730 nm had a different magnitude relationship with the spectral intensity at 450 nm and 560 nm as the thickness of the second wavelength converter 2A increased. Specifically, in Example 10, the spectral intensity at 730 nm was smaller than the spectral intensity at 450 nm and 560 nm. In Example 11, the spectral intensity at 730 nm was larger than the spectral intensity at 450 nm and smaller than the spectral intensity at 560 nm. In Example 12, the spectral intensity at 730 nm was larger than the spectral intensity at 450 nm and 560 nm, and was the strongest among them. In Examples 10 to 12, the spectral intensity at 450 nm was the same as or smaller than the spectral intensity at 730 nm. For example, in Example 11, the spectral intensity was less than 50% of that at 730 nm. In Example 12, the spectral intensity was less than 20%.

[0365] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 containing a strong yellow-green to yellow light component and a strong near-infrared component. When the white light emitted by the white LED is transmitted through the second wavelength converter 2A, the blue light component and the red light component of the light components emitted by the white LED are greatly reduced in intensity. The reason for this is that the Cr contained in the second wavelength converter 2A 3+ This is because the activated phosphor has the property of absorbing blue and red light components. As a result, the output light 4 tends to have a yellowish tinge, so in order to obtain output light 4 close to white light, it is preferable to have a structure that allows part of the light from the white LED (wavelength conversion type light emitting element) to pass through as is.

[0366] Table 4 summarizes the characteristics of the output light 4 of Examples 10 to 12. For comparison, the table also shows the characteristics of Reference Example 3 (a white LED not provided with the second wavelength converter 2A).

[0367] [Table 4]

[0368] As can be seen from Table 4, as the thickness of the second wavelength converter 2A increased, that is, from Example 10 to Example 11 and then to Example 12, the radiant flux, luminous flux and general color rendering index (Ra) tended to decrease. On the other hand, the correlated color temperature tended to maintain a constant value around 4000 K. In addition, in comparison with the case where a second wavelength converter 2A of the same thickness was used, the radiant flux and luminous flux were at a level 40% or more higher than those of Examples 7 to 9. In particular, the radiant flux was at a level 50% or more higher.

[0369] From these data, it can be said that this embodiment is a suitable light emitting device for obtaining output light 4 having both high-power near infrared rays, high radiant flux, and high luminous flux.

[0370] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0371] [Examples 13 to 15] As the light-emitting devices of Examples 13 to 15, light-emitting devices were produced by combining a white LED for LED lighting, which was a combination of a blue LED and a phosphor, with a second wavelength converter 2A. In the same manner as in Examples 4 to 6, the second wavelength converter 2A was placed on the light output surface of a white LED (3000K, manufactured by Lumileds LLC) obtained, and the spectral distribution and radiant flux of the output light 4 output by passing a rated current (400mA) through the white LED were measured.

[0372] Fig. 18 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 13 to 15. (a), (b) and (c) in Fig. 18 correspond to the output light 4 of Examples 13, 14 and 15, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm and 340 μm, respectively. (d) in Fig. 18 shows the spectral distribution (Reference Example 4) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0373] As can be seen from Figures 18(a), (b) and (c), the spectral distribution of the output light 4 includes light components in the entire wavelength range of at least 420 nm to less than 950 nm. The spectral distribution of the output light 4 includes a fluorescent component derived from the blue LED, a fluorescent component derived from the mixed fluorescent component of the green phosphor and the red phosphor, and a fluorescent component derived from the near-infrared phosphor (Cr 3+ The fluorescent component derived from the mixed fluorescent components of the green and red phosphors was mainly derived from the green phosphor (Ce 3+ activated garnet phosphor) and red phosphor (Eu 2+ The fluorescent component derived from the blue LED had a peak at around 450 nm. 3+ activated garnet phosphor) and red phosphor (Eu 2+ The fluorescent component derived from the mixed fluorescent component of the near-infrared phosphor (Cr 3+The fluorescent component originating from the activated garnet phosphor had a peak at around 730 nm.

[0374] Therefore, we focused on the spectral intensities of the light components with wavelengths of 450 nm, 570 nm, 635 nm, and 730 nm. For a white LED that does not use the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the spectral intensity of 635 nm originating from the mixed fluorescent component. The spectral intensity of 450 nm originating from the blue LED and the spectral intensity of 570 nm originating from the mixed fluorescent component showed the next strongest spectral intensity (height).

[0375] In Examples 13 to 15 ((a) to (c) in FIG. 18), which were combined with second wavelength converters 2A of different thicknesses, the spectral intensities of 450 nm, 570 nm, and 635 nm, particularly 450 nm and 635 nm, decreased significantly as the thickness of the second wavelength converter 2A increased. On the other hand, the spectral intensity of 730 nm increased as the thickness of the second wavelength converter 2A increased, and as a result of these influences, the spectral distributions of Examples 13 to 15 had minimum values ​​or depressions in the wavelength range of 600 nm or more and less than 700 nm.

[0376] In Examples 13 to 15, the spectral intensity at 730 nm was greater than that at 570 nm, regardless of the thickness of the second wavelength converter 2A. In particular, in Examples 14 and 15, the spectral intensity was greater than those at 450 nm and 635 nm, and was the strongest among them. In Examples 13 to 15, the spectral intensity at 450 nm was smaller than that at 730 nm, being less than 35%. In particular, in Example 15, the spectral intensity was less than 10%.

[0377] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 containing strong light components over a wide wavelength range from green to yellow to red and strong near-infrared components.

[0378] Table 5 summarizes the characteristics of the output light 4 of Examples 13 to 15. For comparison, the table also shows the characteristics of Reference Example 4 (a white LED not provided with the second wavelength converter 2A).

[0379] [Table 5]

[0380] As can be seen from Table 5, as the thickness of the second wavelength converter 2A increases, that is, from Example 13 to Example 14 and then to Example 15, the radiant flux, luminous flux and general color rendering index (Ra) tend to decrease. On the other hand, the correlated color temperature tends to gradually increase. It should be noted that the radiant flux and luminous flux showed high color rendering with a general color rendering index (Ra) of 75% or more, and when compared with the case where a second wavelength converter 2A of the same thickness was used, the radiant flux and luminous flux were at a level 10% or more higher than those of Examples 10 to 12. In particular, the radiant flux was at a level 50% or more higher.

[0381] From these data, it can be said that this embodiment is a suitable light emitting device for obtaining output light 4 that combines high-output near-infrared radiation, high radiant flux, high luminous flux, and high color rendering properties.

[0382] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0383] [Examples 16 to 18] Light-emitting devices were produced as Examples 16 to 18 by combining a white LED for LED lighting, which was a combination of a blue LED and a phosphor, with a second wavelength converter 2A. In the same manner as in Examples 4 to 6, the second wavelength converter 2A was placed on the light output surface of a white LED (5000K, manufactured by Lumileds LLC) obtained, and the spectral distribution and radiant flux of the output light 4 output by passing a rated current (400mA) through the white LED were measured.

[0384] Fig. 19 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 16 to 18. (a), (b), and (c) in Fig. 19 correspond to the output light 4 of Examples 16, 17, and 18, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm, and 340 μm, respectively. (d) in Fig. 19 shows the spectral distribution (Reference Example 5) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0385] As can be seen from Figures 19(a), (b) and (c), the spectral distribution of the output light 4 includes light components in the entire wavelength range of at least 420 nm to less than 950 nm. The spectral distribution of the output light 4 includes a fluorescent component derived from the blue LED and a fluorescent component derived from the green phosphor (Ce 3+ The fluorescent components derived from the near-infrared phosphor (Cr 3+ The fluorescent components derived from the blue LED had a peak at around 450 nm. The fluorescent components derived from the green phosphor (Ce 3+ The fluorescent component derived from the near-infrared phosphor (Cr 3+ The fluorescent component originating from the activated garnet phosphor had a peak at around 730 nm.

[0386] Therefore, we focused on the spectral intensity of the light components with wavelengths of 450 nm, 555 nm, and 730 nm. In the white LED that did not use the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the spectral intensity of 450 nm originating from the blue LED. The spectral intensity of 555 nm originating from the green phosphor showed the next highest spectral intensity (height).

[0387] In Examples 16 to 18 ((a) to (c) in Figure 19), which were combined with second wavelength converters 2A of different thicknesses, as the thickness of the second wavelength converter 2A increased, the spectral intensity at 450 nm and 555 nm, especially at 450 nm, decreased significantly. On the other hand, as the thickness of the second wavelength converter 2A increased, the spectral intensity at 730 nm increased and had a minimum value in the wavelength range of 600 nm or more and less than 700 nm. The minimum value was less than 60% of the spectral intensity at 730 nm. In particular, in Example 18, it was less than 25%.

[0388] In Examples 16 to 18, the spectral intensities at 450 nm and 730 nm were smaller than the spectral intensity at 555 nm, regardless of the thickness of the second wavelength converter 2A. In Example 16, the spectral intensity at 730 nm was smaller than the spectral intensity at 450 nm, but in Examples 17 and 18 where the thickness was increased, it became larger than the spectral intensity at 450 nm. For example, in Example 16, the spectral intensity at 450 nm was 120% or more of that at 730 nm, but in Example 17, it was less than 50%. In Example 18, it was less than 25%.

[0389] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 that contains a strong yellow-green light component and a strong near-infrared component, with the light components well separated at the boundary around 650 nm.

[0390] Table 6 summarizes the characteristics of the output light 4 of Examples 16 to 18. For comparison, the table also shows the characteristics of Reference Example 5 (a white LED not provided with the second wavelength converter 2A).

[0391] [Table 6]

[0392] As can be seen from Table 6, as the thickness of the second wavelength converter 2A increased, that is, from Example 16 to Example 17 and then to Example 18, the radiant flux, luminous flux and general color rendering index (Ra) tended to decrease. On the other hand, the correlated color temperature tended to gradually increase. Of particular note are the radiant flux and luminous flux, which were at least 7% higher than those of Examples 13 to 15 when a second wavelength converter 2A of the same thickness was used. In particular, the luminous flux was at least 60% higher.

[0393] From these data, it can be said that this embodiment is a suitable light emitting device for obtaining output light 4 having both high-power near infrared rays and high luminous flux.

[0394] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0395] [Examples 19 to 21] Light-emitting devices were produced by combining a white LED for LED lighting with a second wavelength converter 2A as the light-emitting devices of Examples 19 to 21. In the same manner as in Examples 4 to 6, the second wavelength converter 2A was placed on the light output surface of a white LED (3000K, manufactured by Citizen Electronics Co., Ltd.) obtained, and the spectral distribution and radiant flux of the output light 4 output by passing a rated current (180 mA) through the white LED were measured.

[0396] Fig. 20 shows the spectral distributions of the output light 4 of the light emitting devices of Examples 19 to 21. (a), (b), and (c) in Fig. 20 correspond to the output light 4 of Examples 19, 20, and 21, respectively, and correspond to device configurations using second wavelength converters 2A with thicknesses of 155 μm, 240 μm, and 340 μm, respectively. (d) in Fig. 20 shows the spectral distribution (Reference Example 6) of the output light of a white LED (without the second wavelength converter 2A) shown for reference.

[0397] As can be seen from Figures 20(a), (b) and (c), the spectral distribution of the output light 4 includes light components in the entire wavelength range of at least 420 nm to less than 950 nm. The spectral distribution of the output light 4 includes a fluorescent component derived from the blue LED, a fluorescent component derived from the mixed fluorescent component of the green phosphor and the red phosphor, and a fluorescent component derived from the near-infrared phosphor (Cr 3+ The fluorescent component derived from the mixed fluorescent components of the green and red phosphors was mainly derived from the green phosphor (Ce 3+ activated garnet phosphor) and red phosphor (Eu 2+ The fluorescent component derived from the blue LED had a peak at around 450 nm. 3+ activated garnet phosphor) and red phosphor (Eu 2+ The fluorescent component derived from the mixed fluorescent component of the near-infrared phosphor (Cr 3+ The fluorescent component originating from the activated garnet phosphor had a peak at around 730 nm.

[0398] Therefore, we focused on the spectral intensity of the light components with wavelengths of 450 nm, 590 nm, and 730 nm. In the white LED that did not use the second wavelength converter 2A, the fluorescent component with the strongest spectral intensity (height) was the spectral intensity of 590 nm originating from both the green phosphor and the red phosphor. The spectral intensity of 450 nm originating from the blue LED showed the next highest spectral intensity (height).

[0399] In Examples 19 to 21 ((a) to (c) in Figure 20), which were combined with second wavelength converters 2A of different thicknesses, the spectral intensity at 450 nm and 590 nm, especially at 450 nm, decreased significantly as the thickness of the second wavelength converter 2A increased. On the other hand, the spectral intensity at 730 nm increased as the thickness of the second wavelength converter 2A increased, and had a minimum value in the wavelength range of 600 nm or more and less than 700 nm.

[0400] In Examples 19 to 21, the spectral intensity at 730 nm was greater than that at 450 nm, regardless of thickness. And, the spectral intensity at 730 nm was smaller than that at 590 nm in Examples 19 and 20, but was greater in Example 21, becoming the strongest among them.

[0401] The spectral intensity at 450 nm relative to the spectral intensity at 730 nm was, for example, less than 55% in Example 19, less than 25% in Example 20, and less than 15% in Example 21.

[0402] From the above, this embodiment can be said to be a light emitting device suitable for applications requiring output light 4 containing a strong yellow-orange light component and a strong near-infrared component.

[0403] The characteristics of the output light 4 of Examples 19 to 21 are summarized in Table 7. For comparison, the characteristics of Reference Example 6 (a white LED not provided with the second wavelength converter 2A) are also shown in the same table.

[0404] [Table 7]

[0405] As can be seen from Table 7, as the thickness of the second wavelength converter 2A increases, that is, from Example 19 to Example 20 and then to Example 21, the radiant flux, luminous flux, and general color rendering index (Ra) tend to decrease, while the correlated color temperature tends to gradually increase.

[0406] When this output light 4 was irradiated onto a blank sheet of paper, it was confirmed that the light within an area of ​​approximately φ30 cm was homogeneous.

[0407] The spectral distribution of a white LED varies depending on the color tone of the fluorescence (peak fluorescence wavelength) emitted by the LED or phosphor used, or the light absorptance of the first wavelength converter 1A containing the phosphor. The light absorptance of the first wavelength converter 1A varies depending on the volume ratio of the phosphor in the first wavelength converter 1A and the thickness of the first wavelength converter 1A. The light absorptance of the first wavelength converter 1A also varies depending on the activation amount of the fluorescent ions (luminescence centers) of the phosphor used, the composition of the matrix compound, or the particle size (median particle size D 50 ) also depends on the

[0408] For this reason, in addition to the white LED used in this embodiment, white LEDs that emit white light of a wide variety of tones are commercially available, and those skilled in the art can easily obtain these. In other words, it is easy to design the desired illumination light, and it is easy to provide illumination light according to the application. For this reason, the correlated color temperature and color rendering properties of the output light are not limited to those of this embodiment, and the light emitting device of this embodiment that emits illumination light other than that of this embodiment can be implemented.

[0409] In addition, in this example, a resin fluorescent film containing a GLGG phosphor is used as the second wavelength converter 2A, but it is easily conceivable to use an inorganic sealed fluorescent film or fluorescent ceramics instead of the resin fluorescent film in order to increase output.

[0410] For example, fluorescent ceramics can be manufactured by applying the manufacturing technology for translucent YAG fluorescent ceramics and translucent alumina arc tubes. Therefore, even if you do not have the manufacturing technology, you can obtain them, although the quality level may differ, by requesting a prototype from a manufacturer that has the manufacturing technology for translucent YAG fluorescent ceramics.

[0411] The contents of this embodiment have been described above based on examples, but the present embodiment is not limited to these descriptions, and it will be obvious to those skilled in the art that various modifications and improvements are possible.

[0412] The entire contents of Patent Application No. 2021-027328 (filing date: February 24, 2021) are incorporated herein by reference.

[0413] 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. [Industrial Applicability]

[0414] According to the present disclosure, it is possible to provide a light-emitting device that emits both near-infrared and visible light components, is suitable for industrial applications in which consideration can be given to how it is perceived by the human eye, and achieves both high output of near-infrared light components and a large light output surface area, and electronic equipment using the same. [Explanation of symbols]

[0415] 1. The first phosphor 1A First Wavelength Converter 1B First wavelength converted light 1BT2 transmission first wavelength conversion light 2. Second Phosphor 2A Second Wavelength Converter 2B Second wavelength conversion light 3. Solid-state light-emitting devices 3B Primary light 3BT1 first transmitted primary light 3BT2 Secondary transmitted primary light 4 Output Light 5. First Light Component 6 Second Light Component 7. The third light component 10, 10A, 10B, 10C Light-emitting device 14 First Mixed Light 24 Second Mixed Light 117A First Detector 117B Second detector 200, 200D, 200E, 200F, 200G, 200H, 200I Electronic equipment

Claims

1. A light emitting device that includes a solid-state light emitting element, a first wavelength conversion body including a first phosphor, and a second wavelength conversion body including a second phosphor, and that emits output light, The solid-state light emitter emits a primary light; the first wavelength converter absorbs at least a part of the primary light and converts it into first wavelength-converted light having a fluorescence peak within a visible wavelength range of 380 nm or more and less than 780 nm; the second wavelength converter absorbs at least a portion of a first mixed light containing a first transmitted primary light, which is the primary light transmitted through the first wavelength converter, and the first wavelength-converted light, and converts the first mixed light into a second wavelength-converted light having a fluorescence peak in a wavelength region exceeding 700 nm and a near-infrared component in a wavelength region of 780 nm or more and less than 2500 nm; the first mixed light has a light color having a correlated color temperature of 2500 K or more and less than 40000 K; the output light includes at least a transmitted first wavelength-converted light, which is a light component of the first wavelength-converted light transmitted through the second wavelength converter, and a light component of the second wavelength-converted light, A light emitting device, wherein the output light has an integral value of energy intensity of a light component with a wavelength of less than 700 nm that is greater than an integral value of energy intensity of a light component with a wavelength of 700 nm or more.

2. A light emitting device that includes a solid-state light emitting element, a first wavelength conversion body including a first phosphor, and a second wavelength conversion body including a second phosphor, and that emits output light, The solid-state light emitter emits a primary light; the first wavelength converter absorbs at least a part of the primary light and converts it into first wavelength-converted light having a fluorescence peak within a visible wavelength range of 380 nm or more and less than 780 nm; the second wavelength converter absorbs at least a portion of a first mixed light containing a first transmitted primary light, which is the primary light transmitted through the first wavelength converter, and the first wavelength-converted light, and converts the first mixed light into a second wavelength-converted light having a fluorescence peak in a wavelength region exceeding 700 nm and a near-infrared component in a wavelength region of 780 nm or more and less than 2500 nm; the first mixed light has a light color having a correlated color temperature of 2500 K or more and less than 40000 K; the output light includes at least a transmitted first wavelength-converted light, which is a light component of the first wavelength-converted light transmitted through the second wavelength converter, and a light component of the second wavelength-converted light, The light emitting device, wherein the output light has a luminous flux of 291.6 lm or more.

3. 3. The light emitting device according to claim 1, wherein the solid-state light emitting element and the first wavelength converter are combined to form a wavelength conversion type light emitting element.

4. 4. The light emitting device according to claim 1, wherein the output light has a color having a correlated color temperature of 2600K or more and less than 12000K.

5. 5. The light emitting device according to claim 1, further comprising a control mechanism for controlling an output ratio of a light component of the second wavelength-converted light.

6. 6. The light emitting device according to claim 1, which alternately outputs output light containing a light component of the second wavelength-converted light and output light not containing the light component.

7. 7. The light emitting device according to claim 1, wherein the first wavelength converter contains a red phosphor that emits light having a fluorescent peak in a red wavelength region of not less than 600 nm and less than 660 nm.

8. The first phosphor contained in the first wavelength converter is Ce. ３＋ 8. The light emitting device according to claim 1, wherein the phosphor is activated with .

9. 9. The light emitting device according to claim 1, wherein at least the second wavelength converter has a property of transmitting at least the second wavelength converted light.

10. The second phosphor contains Cr as a fluorescent ion. ３＋ The light emitting device according to any one of claims 1 to 9, comprising:

11. The light emitting device according to any one of claims 1 to 10, which is a light source for a sensing system or an illumination system for a sensing system.

12. An electronic device comprising the light emitting device according to any one of claims 1 to 11.

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