Light emitting device and electronic device using the same

Abstract

A light emitting device (10) includes a first light emitting element (5) that emits a first light component (1), a second light emitting element (6) that emits a second light component (2), a first phosphor (7) that emits a third light component (3), and a second phosphor (8) that emits a fourth light component (4). The first light component (1) and the second light component (2) are light components each having an intensity maximum at a wavelength of 380 nm or more and less than 700 nm. The third light component is a light component having an intensity maximum at a wavelength of 435 nm or more and less than 700 nm. The fourth light component is a near-infrared light component having an intensity maximum at a wavelength of 700 nm or more and less than 2500 nm. The spectral distribution of an output light (9) has a trough portion (T) in a wavelength range of 650 nm or more and 750 nm or less, and the minimum intensity in the wavelength range is less than 30% of the maximum intensity in a wavelength range of 380 nm or more and 2500 nm or less.

Description

Technical Field

[0001] This invention relates to a light-emitting device and an electronic device using the light-emitting device. Background Technology

[0002] Previously, there were known light-emitting devices that combined a light-emitting element with a phosphor and emitted output light containing near-infrared light components (see Patent Document 1).

[0003] The light-emitting device of Patent Document 1 includes Cr 3+ and / or Ni 2+ It comprises a wavelength converter for a phosphor that serves as the light-emitting center and a semiconductor chip that emits excitation light. Furthermore, near-infrared light is generated by converting the wavelength of blue or red light emitted from the semiconductor chip using the wavelength converter. Additionally, in the embodiment of Patent Document 1, the performance of the light-emitting device (photoelectric element) is mentioned, with the output of the obtained near-infrared light being less than 50mW.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6570653 Summary of the Invention

[0007] Conventional light-emitting devices, which combine a light-emitting element with a phosphor and emit near-infrared light components, are sometimes combined with detectors that detect near-infrared wavelengths. In this case, the light-emitting device emits output light with a spectral distribution necessary to ensure good sensitivity of the detector. That is, conventional light-emitting devices emit output light that focuses on the object being detected with high sensitivity, regardless of how bright it appears to the human eye.

[0008] Therefore, when inspecting an object while visually observing it, conventional light-emitting devices that emit near-infrared light may make the object difficult to see or create an unpleasant visual experience. Furthermore, conventional light-emitting devices do not adequately consider the separation of visible and near-infrared light. Therefore, optical filters are necessary to achieve a good signal-to-noise ratio (S / N ratio) for near-infrared detectors, leading to complex device structures.

[0009] This invention was made in view of the problems inherent in such conventional technologies. Furthermore, the object of this invention is to provide a light-emitting device that, when used in combination with a near-infrared detector, allows for the effective visual inspection of an object, in addition to the use of a detector, as well as an electronic device using the light-emitting device.

[0010] To address the aforementioned issues, the first technical solution of the present invention provides a light-emitting device that emits output light, comprising: a first light-emitting element emitting a first light component; a second light-emitting element, different from the first light-emitting element, emitting a second light component; a first phosphor emitting a third light component; and a second phosphor, different from the first phosphor, emitting a fourth light component. The output light includes the first, second, third, and fourth light components with different hues. The first and second light components are visible light components having a maximum intensity in a wavelength range of 380 nm or more and less than 700 nm. The third light component is a visible light component originating from the first wavelength-converted light emitted by the first phosphor, having a maximum intensity in a wavelength range of 435 nm or more and less than 700 nm. The fourth light component is a near-infrared light component originating from the second wavelength-converted light emitted by the second phosphor, having a maximum intensity in a wavelength range of 700 nm or more and less than 2500 nm. The output light has a trough in the wavelength range of 650nm to 750nm, and the minimum intensity in the wavelength range of 650nm to 750nm is less than 30% of the maximum intensity in the wavelength range of 380nm to 2500nm.

[0011] The electronic device according to the second technical solution of the present invention includes the above-described light-emitting device. Attached Figure Description

[0012] Figure 1 This is a graph showing an example of the spectral distribution of the output light emitted by the light-emitting device of this embodiment.

[0013] Figure 2 This is a schematic diagram showing an example of the structure of the light-emitting device according to this embodiment.

[0014] Figure 3 This is a schematic diagram showing another example of the structure of the light-emitting device according to this embodiment.

[0015] Figure 4 This is a schematic diagram showing another example of the structure of the light-emitting device according to this embodiment.

[0016] Figure 5 This is a schematic diagram showing another example of the structure of the light-emitting device according to this embodiment.

[0017] Figure 6 This is a schematic diagram showing another example of the structure of the light-emitting device according to this embodiment.

[0018] Figure 7 This is a schematic diagram illustrating an example of the structure of the electronic device according to this embodiment.

[0019] Figure 8 This is a schematic diagram showing another example of the structure of the electronic device according to this embodiment.

[0020] Figure 9 It is a graph showing the spectral distribution of the white LED and the red LED used in the embodiment.

[0021] Figure 10 This is a graph showing an example of the spectral distribution of a white LED that can be made using a blue LED and a YAG phosphor.

[0022] Figure 11 This is a schematic diagram showing the structure of the light-emitting device in the relevant embodiment.

[0023] Figure 12 It is a graph showing the spectral distribution of the output light emitted from the light-emitting devices of Examples 1 to 3.

[0024] Figure 13 This is a graph showing the spectral distribution obtained by adjusting the proportion of green light component for the spectral distribution in Example 2. Detailed Implementation

[0025] Hereinafter, the light-emitting device of this embodiment and the electronic device using the light-emitting device will be described with reference to the accompanying drawings. Furthermore, the embodiments described below are all preferred examples. Therefore, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, and connection methods shown in the following embodiments are merely examples and are not intended to limit this embodiment. Figures 2 to 8 and Figure 11 It is a schematic diagram, not necessarily a rigorous one. Furthermore, in Figures 2 to 8 and Figure 11 In Chinese, the same labels are assigned to the same structures, and repeated descriptions are omitted or simplified.

[0026] Figure 1 This is an example of the spectral distribution of the output light emitted by the light-emitting device of this embodiment. Figures 2 to 6 The structure of the light-emitting device of this embodiment is shown in a simplified manner. The light-emitting device 10 of this embodiment is a light-emitting device that combines at least two kinds of light-emitting elements 5 and 6 and at least two kinds of phosphors 7 and 8 and emits output light 9.

[0027] [Output Light]

[0028] like Figure 1 As shown, the output light 9 emitted by the light-emitting device in this embodiment includes at least a first light component 1, a second light component 2, a third light component 3, and a fourth light component 4 with different hues.

[0029] The first light component 1 is the light component originating from the light emitted by the first light-emitting element 5 (primary light), and the second light component 2 is the light component originating from the light emitted by the second light-emitting element 6 (primary light). These light components are visible light components with maximum intensity in the wavelength range of 380 nm to less than 700 nm, preferably 435 nm to less than 670 nm.

[0030] The third light component 3 is a light component derived from the first wavelength-converted light 3A emitted by the first phosphor 7, and is a visible light component having a maximum intensity in the wavelength range of 435 nm to less than 700 nm, preferably 500 nm to less than 600 nm.

[0031] The fourth light component 4 is near-infrared light originating from the second wavelength-converted light 4A emitted by the second phosphor 8, having a maximum intensity in the wavelength range of 700 nm to 2500 nm, preferably 750 nm to 1800 nm. Furthermore, the upper limit of this wavelength range, i.e., the longest wavelength, can also be 800 nm, 900 nm, 1000 nm, 1200 nm, or 1500 nm.

[0032] The output light 9 contains visible light components that can be recognized by the human eye, namely the first light component 1, the second light component 2, and the third light component 3, as well as a near-infrared light component that is difficult to see by the human eye, namely the fourth light component 4. Therefore, by using the output light 9, the illuminated object can be identified by the human eye, and non-destructive inspection of its interior can be performed by methods such as near-infrared spectroscopy.

[0033] Furthermore, the light-emitting device 10 emits output light 9 having at least four additively mixed hues. That is, the output light 9 includes primary light (a first light component and a second light component emitted by the light-emitting element) obtained by converting electrical power, and wavelength-converted light (a first wavelength-converted light and a second wavelength-converted light obtained by wavelength conversion of the primary light by the first phosphor and the second phosphor). Therefore, by controlling the power supplied to the first light-emitting element 5 and the second light-emitting element 6, the output intensity of the first light component 1 and the second light component 2 can be controlled independently. Furthermore, by changing the types of the first phosphor 7 and the second phosphor 8, the hues of the third light component 3 and the fourth light component 4 can also be controlled independently.

[0034] In this way, the light-emitting device 10 can release output light that is easy to meet customers' expectations for the recognizability of the illuminated object and its non-destructive inspection, and is suitable for both the human eye and the detector.

[0035] The output light 9 has a trough T in the wavelength range of 650 nm to 750 nm. Furthermore, the minimum intensity in the wavelength range of 650 nm to 750 nm is preferably less than 30% of the maximum intensity in the wavelength range of 380 nm to 2500 nm, particularly 380 nm to 960 nm. More preferably, this minimum intensity is less than 20% of the maximum intensity in the wavelength range of 380 nm to 2500 nm, particularly 380 nm to 960 nm, and even more preferably less than 10%. In this case, the interference between the mixed light component of the first light component 1 (mainly visible light component), the second light component 2, and the third light component 3, and the fourth light component 4 (containing near-infrared light component) is reduced. That is, a spectral distribution is achieved where the visible light component and the near-infrared light component are separated to some extent with a wavelength around 700 nm as the boundary. Therefore, in detectors that detect the near-infrared light component transmitted or reflected by an object irradiated with output light 9, the S / N ratio (signal-to-noise ratio) can be improved.

[0036] Such a spectral distribution can be obtained by having the light-emitting element (first light-emitting element 5 or second light-emitting element 6) emit a light component that is closest to the short wavelength side of the fourth light component 4, and make it light with a narrow spectral half-width. In other words, such a spectral distribution can be obtained by having the light-emitting element emit a light component located in the longest wavelength side of the wavelength range above 380 nm and below 700 nm, and make it light with a narrow spectral half-width.

[0037] In applications such as optical interferometry (OI) where the detection signal is Fourier transformed after the near-infrared light component is detected by a detector, the spectral distribution of the fourth light component 4 preferably has a single peak. Furthermore, the spectral distribution of the fourth light component 4 is more preferably a normal distribution or a distribution close to it. Moreover, in this case, the spectral distribution of the fourth light component 4 preferably exhibits wavelength dependence of intensity in the wavelength region exceeding 700 nm without abrupt changes. Specifically, in the wavelength region exceeding 700 nm, the intensity of the spectral distribution preferably varies by no more than ±8% / nm, and more preferably by no more than ±3% / nm.

[0038] Furthermore, if we express the degree to which the spectral distribution approximates a normal distribution numerically, it is as follows. In the fourth optical component 4, let λ be the wavelength exhibiting the maximum intensity. P Let the wavelengths of the short-wavelength side and the long-wavelength side, where the intensity is half of the maximum intensity, be λ, respectively. S and λ L At this time, λ P , λ S and λ L Satisfying 1≤(λ)L -λ P ) / (λ P -λ S ) < 2.0, preferably satisfying 1 ≤ (λ) L -λ P ) / (λ P -λ S )<1.8.

[0039] Thus, by ensuring that the spectral distribution of the fourth optical component 4 has a normal distribution or a distribution close to it, the generation of spurious signals after the Fourier transform can be suppressed. Therefore, the detector can detect a high-quality detection signal.

[0040] At least one of the first light component 1, the second light component 2, and the third light component 3 is preferably a blue-green to green-yellow to orange light component with a wavelength of 510 nm or more and less than 600 nm. Furthermore, at least one of the first light component 1, the second light component 2, and the third light component 3 is more preferably a green to yellow light component with a wavelength of 530 nm or more and less than 580 nm, and even more preferably a green light component with a wavelength of 545 nm or more and less than 565 nm. Such light components have a strong intensity perceived by the human eye, thus resulting in a perceived brightness. Therefore, it becomes a light-emitting device 10 that emits output light 9 that is easily identifiable to the irradiated object.

[0041] In the light-emitting device 10, at least one of the first light component 1, the second light component 2, and the third light component 3 is preferably a blue-blue-green-green light component with a wavelength of 460 nm or more and less than 550 nm. Furthermore, at least one of the first light component 1, the second light component 2, and the third light component 3 is more preferably a blue-green-green light component with a wavelength of 480 nm or more and less than 530 nm, and even more preferably a blue-green-green light component with a wavelength of 490 nm or more and less than 520 nm. Such light components, when observed in low-light conditions, have a strong intensity perceived by the human eye, thus allowing the light to be perceived as bright. Therefore, the light-emitting device 10 becomes one that emits output light 9 that is easily identifiable in the dark.

[0042] In the light-emitting device 10, at least one of the first light component 1, the second light component 2, and the third light component 3 is preferably a light component with a wavelength of 610 nm or more and less than 670 nm, and more preferably a red light component with a wavelength of 630 nm or more and less than 660 nm. Such a light component has the light that makes the skin color or red color of the irradiated object look beautiful or appear bright. Therefore, the light-emitting device 10 becomes a light-emitting device that emits output light 9 that makes the face or skin of the irradiated person look good, or the appearance of red edible meat or fruit, etc.

[0043] Furthermore, when the fourth light component 4 starts at a wavelength of 850 nm, it is preferable that its intensity decreases as the wavelength increases. Additionally, the fourth light component 4 can make the fluorescence intensity at a wavelength of 1000 nm less than 10% of the fluorescence intensity at a wavelength of 850 nm. Furthermore, the starting wavelength is preferably shorter than 850 nm, for example, it can be set to 800 nm. Specifically, when the fourth light component 4 starts at a wavelength of 800 nm, it is preferable that its intensity decreases as the wavelength increases. Furthermore, the fourth light component 4 can make the fluorescence intensity at a wavelength of 1000 nm less than 10% of the fluorescence intensity at a wavelength of 800 nm, and further, it can make the fluorescence intensity at a wavelength of 950 nm less than 10% of the fluorescence intensity at a wavelength of 800 nm. In this way, it becomes an output light 9 with a small proportion of near-infrared or mid-infrared rays in the long wavelength region, which easily function as heat rays. Therefore, it becomes a light-emitting device 10 that is advantageous for inspecting objects such as food that are easily affected by heat.

[0044] The fourth light component 4 preferably has a spectral half-width, i.e., the wavelength difference between the long-wavelength side and the short-wavelength side of the spectrum where the maximum intensity of the fourth light component 4 is half, exceeding 70 nm, and more preferably exceeding 100 nm. This results in output light 9 with near-infrared light components covering a large wavelength range and having different wavelengths. Therefore, it becomes a light-emitting device 10 that is advantageous for inspecting and evaluating objects whose near-infrared light absorption wavelengths differ or are easily affected by the surrounding environment.

[0045] Here, the light obtained by mixing the first light component 1, the second light component 2, and the third light component 3 preferably contains a blue light component, a blue-green to green-yellow light component, and a red light component. The blue light component is preferably a light component in the wavelength range of 435 nm or more and less than 480 nm, and more preferably a light component with a maximum intensity within this wavelength range. The blue-green to green-yellow light component is preferably a light component in the wavelength range of 500 nm or more and less than 580 nm, and more preferably a light component with a maximum intensity within this wavelength range. The red light component is preferably a light component in the wavelength range of 600 nm or more and less than 700 nm, and more preferably a light component with a maximum intensity within this wavelength range. Therefore, the output light 9 contains blue, green, and red light components, which are the three primary colors of light, thus becoming a light-emitting device 10 capable of outputting visible light with high color rendering. Furthermore, it becomes a light-emitting device 10 that facilitates the accurate representation of the irradiated object. Moreover, since it emits more of the three primary colors of light and near-infrared light components, it becomes a light-emitting device 10 with good compatibility with imaging technology known as RGB-NIR imaging.

[0046] The first light component 1 can be set as a blue light component that originates from the first primary light 1A emitted by the first light-emitting element 5 and has a maximum intensity in the wavelength range of 435 nm to less than 480 nm. Furthermore, the first light component 1 is preferably a blue light component with a maximum intensity in the wavelength range of 440 nm to less than 470 nm. Such a first light component 1 can be obtained using conventional solid-state light-emitting elements such as light-emitting diodes (LEDs) or laser diodes (LDs) that emit blue light. Therefore, it becomes a light-emitting device 10 that facilitates rapid product development and industrial production.

[0047] The second light component 2 can be a green to yellow light component that originates from the second primary light 2A emitted by the second light-emitting element 6 and has a maximum intensity in the wavelength range of 500 nm to 580 nm, preferably a green light component that has a maximum intensity in the wavelength range of 510 nm to 560 nm. Alternatively, the second light component 2 can be a red light component that originates from the second primary light 2A emitted by the second light-emitting element 6 and has a maximum intensity in the wavelength range of 600 nm to 680 nm, preferably a red light component that has a maximum intensity in the wavelength range of 610 nm to 660 nm.

[0048] The third light component 3 can be a green-yellow-orange-red light component originating from the first wavelength-converted light 3A emitted by the first phosphor 7, and having a maximum intensity in the wavelength range of 500 nm to 700 nm. Alternatively, the third light component 3 can be a green-yellow-orange light component originating from the first wavelength-converted light 3A emitted by the first phosphor 7, and having a maximum intensity in the wavelength range of 500 nm to 600 nm. Finally, the third light component 3 can be a green light component originating from the first wavelength-converted light 3A emitted by the first phosphor 7, and having a maximum intensity in the wavelength range of 520 nm to 560 nm.

[0049] If the second light component 2 and the third light component 3 are set as described above, then in the output light 9, the first light component 1 emitted by the first light-emitting element 5, the second light component 2 emitted by the second light-emitting element 6, and the third light component 3 emitted by the first phosphor 7 form the three primary colors of light. Therefore, by controlling the intensity and hue of each light component, the hue of the output light 9 can be controlled within a large chromaticity range, thereby obtaining output light 9 with high color rendering.

[0050] Furthermore, the second light component 2 is preferably a red light component originating from the second primary light 2A emitted by the second light-emitting element 6, and having a maximum intensity in the wavelength range of 600 nm to 680 nm. More preferably, the second light component 2 is a red light component originating from the second primary light 2A emitted by the second light-emitting element 6, and having a maximum intensity in the wavelength range of 610 nm to 660 nm. In this case, the spectral half-width can be narrowed for the light component having a maximum intensity in the red wavelength range. Therefore, the light-emitting device 10 becomes one that easily balances high output and high color rendering of the visible light component of the output light 9.

[0051] The fourth light component 4 is preferably the light after the second light component 2 has been wavelength-converted by the second phosphor 8, i.e., the second wavelength-converted light 4A. In this case, the energy difference (Stokes shift) between light absorption and fluorescence emission based on the second phosphor 8 can be reduced. Therefore, the phenomenon of the second phosphor 8 heating up due to energy loss during wavelength conversion from visible light to near-infrared light and extinction due to the increase in the phosphor's temperature (temperature extinction) can be suppressed. Thus, a light-emitting device 10 that favors high output of the near-infrared light component is achieved.

[0052] The third light component 3 is preferably the light after the first light component 1 has been wavelength-converted by the first phosphor 7, i.e., the first wavelength-converted light 3A. In this case, the energy difference between light absorption and fluorescence emission based on the first phosphor 7 can be reduced. Therefore, the phenomenon of the first phosphor 7 heating up due to energy loss as it converts from visible light to longer wavelengths, and the extinction due to the increased temperature of the phosphor, can be suppressed. Thus, the light-emitting device 10 is capable of outputting the third light component 3 with a high photon conversion efficiency.

[0053] In the output light 9, the integral value of the energy intensity of the light component with a wavelength less than 700 nm can be greater than the integral value of the energy intensity of the light component with a wavelength greater than 700 nm. Furthermore, the integral value of the energy intensity of the light component with a wavelength less than 700 nm can be more than twice, or even more than three times, the integral value of the energy intensity of the light component with a wavelength greater than 700 nm. In this case, the energy intensity of visible light with high visibility becomes greater than the energy intensity of the light component containing near-infrared light with low visibility. Therefore, it is easier to make the illuminated object appear bright to the human eye, and thus, non-destructive inspection of the illuminated object can be performed as needed.

[0054] Furthermore, in the output light 9, the integral value of the energy intensity of the light component with a wavelength less than 700 nm can be smaller than the integral value of the energy intensity of the light component with a wavelength greater than 700 nm. Moreover, the integral value of the energy intensity of the light component with a wavelength less than 700 nm can also be less than half or less than one-third of the integral value of the energy intensity of the light component with a wavelength greater than 700 nm. If this is the case, the energy intensity of the light component containing near-infrared light becomes greater than the energy intensity of visible light. Therefore, such an output light 9 is suitable for high-precision non-destructive inspection, non-destructive inspection of small objects, non-destructive inspection of large areas, and non-destructive inspection of large or thick objects. Furthermore, the surface condition of the irradiated object can be easily confirmed with the human eye as needed. In addition, since the output light 9 emits a small proportion of visible light components, it is also an advantageous light-emitting device in reducing glare from the output light 9.

[0055] In the light-emitting device 10, the output light 9 can be made white. For example, it is preferable to appropriately combine the first light component 1, the second light component 2, and the third light component 3, and make the output light white by additive color mixing. If so, the light-emitting device 10 simultaneously emits light with a tone close to natural light and high-output near-infrared rays, and can be used for both general lighting and industrial lighting. Therefore, the light-emitting device 10 can be used as a detection device for detecting the state of an irradiated object in an environment where it is irradiated in a state close to natural light, and as an inspection device for inspecting the internal structure or defects of the irradiated object.

[0056] In the light-emitting device 10, the average color rendering index Ra of the white output light 9 is preferably greater than 80, and more preferably greater than 90. In this case, the high color rendering light makes vegetables, fruits, meat, and fresh fish appear fresher. Furthermore, by detecting the reflected or transmitted light from the near-infrared light illuminating these items, the internal damage or freshness can be evaluated. Therefore, for example, the damage condition of vegetables and fruits displayed in the store can be assessed without being noticed by a third party, and they can be removed from the store as quickly as possible if damage is confirmed.

[0057] Furthermore, high color rendering light can make a person's face, skin, and internal organs appear more aesthetically pleasing. On the other hand, by detecting reflected or transmitted near-infrared light, it is possible to evaluate a person's health status or disease. Moreover, high color rendering light allows one to perceive a vitality in plants and animals that closely resembles nature. Furthermore, near-infrared light can be used to evaluate the health status or injury status of plants and animals. In addition, by achieving a level of illumination comparable to natural light using high color rendering light, it is possible to monitor and measure the irradiated object imperceptibly using near-infrared light.

[0058] The white output light 9 can have a spectral intensity across the entire wavelength range of at least 440 nm and less than 660 nm. Furthermore, the white output light 9 can also have a spectral intensity across the entire wavelength range of at least 430 nm and less than 900 nm. That is, the light can be made to have a spectral distribution in which there are no wavelength components with zero intensity within the aforementioned wavelength range. Such output light 9 can illuminate an object with a greater variety of wavelengths. Furthermore, the output light 9 preferably has a spectral intensity spanning the entire range from the short-wavelength visible region (blue-violet) to the near-infrared region. Therefore, it can be applied to hyperspectral imaging, which captures reflected light that varies depending on the wavelength of illumination and then focuses it to visualize the features of the illuminated object.

[0059] in addition, Figure 1 The solid line represents an example of the spectral distribution of the output light 9 of a light-emitting device using the following elements as a first light-emitting element 5, a second light-emitting element 6, a first phosphor 7, and a second phosphor 8. The first light-emitting element 5 uses a blue light-emitting diode, and the peak wavelength of the first light component 1 is 450 nm. The second light-emitting element 6 uses a red light-emitting diode, and the peak wavelength of the second light component 2 is 635 nm. The first phosphor 7 uses a Ce-based light-emitting diode... 3+ The activated yttrium aluminum garnet phosphor has a fluorescence peak wavelength of 535 nm for the third optical component 3. Cr-coated phosphor 8 is used as the second phosphor. 3+ The activated gadolinium gallium garnet phosphor has a fluorescence peak wavelength of 765 nm for the fourth optical component 4.

[0060] like Figure 1 As shown by the solid line, the output light 9 has a trough T in the wavelength range of 650nm to 750nm. The visible light component and the near-infrared light component are separated at the trough T. Furthermore, the minimum intensity in the wavelength range above 650nm and below 750nm, i.e., the intensity near wavelength 690nm, is less than 30% of the maximum intensity in the wavelength range above 380nm and below 2500nm, i.e., the intensity near wavelength 450nm.

[0061] In addition, by Figure 1 The solid lines represent the correlated color temperature, duv (an index representing the shift relative to blackbody radiation), and average color rendering index Ra of the spectral distribution, which are 8115 K, 0.6, and 93, respectively. Thus, since duv is within ±1, it can be said to be close to the color of natural light. Furthermore, since Ra exceeds 90, Figure 1 The output light of the solid line has a high color rendering index, close to that of natural light.

[0062] Figure 1The dashed lines represent an example of the spectral distribution of the output light 9 of a light-emitting device using the following elements as a first light-emitting element 5, a second light-emitting element 6, a first phosphor 7, and a second phosphor 8. The first light-emitting element 5 uses a blue light-emitting diode, and the peak wavelength of the first light component 1 is 450 nm. The second light-emitting element 6 uses a red light-emitting diode, and the peak wavelength of the second light component 2 is 660 nm. The first phosphor 7 uses a Ce... 3+ The activated yttrium aluminum garnet phosphor has a fluorescence peak wavelength of 555 nm for the third optical component 3. Cr-coated phosphor 8 is used as the second phosphor. 3+ The activated gadolinium gallium garnet phosphor has a fluorescence peak wavelength of 765 nm for the fourth optical component 4.

[0063] like Figure 1 As shown by the dashed line, the output light 9 has a trough T in the wavelength range of 650nm to 750nm. The visible light component and the near-infrared light component are separated at the trough T. Furthermore, the minimum intensity in the wavelength range above 650nm and below 750nm, i.e., the intensity near wavelength 690nm, is less than 30% of the maximum intensity in the wavelength range above 380nm and below 2500nm, i.e., the intensity near wavelength 770nm.

[0064] Depend on Figure 1 The dashed line represents the correlated color temperature, duv, and average color rendering index Ra of the spectral distribution, which are 4839 K, -13.6, and 86, respectively. Here, since a correlated color temperature suitable for general lighting is above 2800 K and below 7000 K, therefore... Figure 1 The dashed line indicates that the output light is suitable for general lighting. Furthermore, although the dual is within ±30, the Ra exceeds 85, so... Figure 1 The output light of the dotted line also has a high color rendering index, close to that of natural light.

[0065] Furthermore, the values ​​of correlated color temperature, duv, and average color rendering index (Ra) can be set to desired values ​​by adjusting the spectral distribution using light source technology relevant to lighting design. For example, the correlated color temperature can be adjusted to any value within the range of 2800K to less than 18000K, particularly 3000K to less than 8000K. Additionally, the average color rendering index (Ra) can be adjusted to any value within the range of 70 to less than 100, particularly 80 to less than 98. The duv can be adjusted to any value within the range of -30 to less than 30, particularly -10 to less than 10.

[0066] Furthermore, light with a low correlated color temperature is close to the color of light emitted by a light bulb, while light with a high correlated color temperature is close to the color of sunlight during the day. Light with a low average color rendering index (CRI) is conducive to high beam brightness, while light with a high CRI is close to natural light. Light with a low Duv (Duration of Visibility) has less green content and a purplish tint, while light with a high Duv has a green tint that increases visibility and is conducive to high beam brightness. Light with a Duv close to zero is close to the hue of natural light.

[0067] exist Figure 1 In the spectral distribution, the first light component 1 originates from the blue light 1A emitted by the blue light-emitting diode (first light-emitting element 5) as the first primary light source. The second light component 2 originates from the red light 2A emitted by the red light-emitting diode (second light-emitting element 6) as the second primary light source. The third light component 3 originates from the Ce-coated light source of the first phosphor 7. 3+ The visible conversion light emitted by the activated yttrium aluminum garnet-type phosphor. The fourth light component 4 originates from the Cr-coated phosphor 8, which is the second phosphor. 3+ Visible conversion light emitted by an activated gadolinium gallium garnet phosphor.

[0068] The spectral distribution of output light 9 is as follows Figure 1 As shown by the solid line, it is preferable that the intensity of the light component with a wavelength of 380 nm or more and less than 700 nm reaches its maximum value. In particular, the maximum intensity of the light component with a wavelength less than 700 nm in the spectral distribution of the output light 9 is preferably more than 1.5 times the maximum intensity of the light component with a wavelength greater than 700 nm, more preferably more than 2 times, and even more preferably more than 3 times. Thus, it becomes a light-emitting device with a high proportion of visible light component and high conversion efficiency to visible light component.

[0069] The spectral distribution of output light 9 is as follows Figure 1 As shown by the dashed line, it is also preferable that the intensity of the light component with a wavelength of 700 nm or more reaches its maximum value. In particular, the maximum intensity of the light component with a wavelength of 700 nm or more in the spectral distribution of the output light 9 is preferably more than 1.5 times the maximum intensity of the light component with a wavelength of 380 nm or more but less than 700 nm, more preferably more than 2 times, and even more preferably more than 3 times.

[0070] Furthermore, the maximum intensity of the light component with a wavelength 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%. Thus, it becomes a light-emitting device with a high proportion of near-infrared light component and high conversion efficiency to near-infrared light component.

[0071] In addition, the beam distribution of output light 9 is as follows: Figure 1As shown, the preferred embodiment is one that substantially does not contain any light components in the ultraviolet region with wavelengths shorter than 380 nm. This results in a light-emitting device capable of converting input electricity only into visible and infrared light, exhibiting high energy conversion efficiency in these light sources.

[0072] The preferred spectral distribution of output light 9 is that it is derived from Cr as the fourth light component 4. 3+ Ionic 4 T2→ 4 The A2 exhibits a broad fluorescence component due to its electronic energy transitions. Furthermore, this fluorescence component preferably has a fluorescence peak in the wavelength region above 700 nm. Therefore, the output light 9 possesses a near-infrared component covering a wide wavelength range, enabling the light-emitting device 10 to be appropriately used for hyperspectral imaging.

[0073] The output light 9 preferably has a light component covering the entire visible wavelength region, from at least 410 nm to less than 700 nm, and more preferably from 380 nm to less than 780 nm. This allows the illuminated object to be identified by the human eye. Furthermore, it is a light-emitting device that emits light components usable for spectral imaging across the entire visible wavelength range.

[0074] [Structure of the light-emitting device]

[0075] Next, the specific structure of the light-emitting device of this embodiment will be described.

[0076] like Figures 2 to 6 As shown, the light-emitting device 10 of this embodiment is composed of at least a first light-emitting element 5, a second light-emitting element 6, a first wavelength converter 7A, and a second wavelength converter 8A. The first light-emitting element 5 emits first primary light 1A as the source of the first light component 1. The second light-emitting element 6 emits second primary light 2A as the source of the second light component 2. The first wavelength converter 7A emits first wavelength converted light 3A as the source of the third light component 3. The second wavelength converter 8A emits second wavelength converted light 4A as the source of the fourth light component 4.

[0077] The first wavelength converter 7A includes a first phosphor 7, and the second wavelength converter 8A includes a second phosphor 8. Alternatively, the first wavelength converter 7A and the second wavelength converter 8A can be integrated. That is, as shown... Figure 3 As shown, a wavelength converter can also include both a first phosphor 7 and a second phosphor 8.

[0078] The first primary light 1A and the second primary light 2A, like the first light component 1 and the second light component 2, are light components with different hues. Furthermore, the first primary light 1A and the second primary light 2A are preferably visible light components with a maximum intensity in a wavelength range of 380 nm to 700 nm, and more preferably visible light components with a maximum intensity in a wavelength range of 435 nm to 670 nm. For example, the first primary light 1A can be set to light with a maximum intensity in a wavelength range of 435 nm to 560 nm, and preferably light with a maximum intensity in a wavelength range of 440 nm to 480 nm. The second primary light 2A can be set to light with a maximum intensity in a wavelength range of 500 nm to 700 nm, and preferably light with a maximum intensity in a wavelength range of 610 nm to 670 nm.

[0079] Like the third light component 3, the first wavelength-converted light 3A is a visible light component with a maximum intensity in the wavelength range of 435 nm to 700 nm. For example, the first wavelength-converted light 3A can be set to be light with a maximum intensity in the wavelength range of 500 nm to 600 nm, and preferably light with a maximum intensity in the wavelength range of 510 nm to 560 nm.

[0080] Like the fourth light component 4, the second wavelength-converted light 4A is a near-infrared light component with a maximum intensity in the wavelength range of 700 nm to 2500 nm. For example, the second wavelength-converted light 4A can be set to have a maximum intensity in the wavelength range of 750 nm to 1800 nm, and preferably to have a maximum intensity in the wavelength range of 780 nm to 1500 nm.

[0081] (First light-emitting element 5, second light-emitting element 6)

[0082] The first light-emitting element 5 is a light-emitting element that emits a first primary light 1A, and the second light-emitting element 6 is a light-emitting element that emits a second primary light 2A. For example, solid-state light-emitting elements such as light-emitting diodes or laser diodes can be used as the first light-emitting element 5 and the second light-emitting element 6.

[0083] Furthermore, by using an LED module or laser diode that emits light with energy of 1W or more as the first light-emitting element 5 and the second light-emitting element 6, a light-emitting device 10 capable of expecting light output in the hundreds of mW range is created. If an LED module that emits light with energy of 3W or more or 10W or more as the first light-emitting element 5 and the second light-emitting element 6 is used, a light-emitting device 10 capable of expecting light output in the several W range is created. Moreover, by using an LED module that emits light with energy of 30W or more as the first light-emitting element 5 and the second light-emitting element 6, a light-emitting device 10 capable of expecting light output exceeding 10W is created. And by using an LED module that emits light with energy of 100W or more as the first light-emitting element 5 and the second light-emitting element 6, a light-emitting device 10 capable of expecting light output exceeding 30W is created.

[0084] Furthermore, a laser diode can be used, making at least one of the first primary light 1A and the second primary light 2A a laser. This allows for high-density spotlight illumination of at least one of the first wavelength converter 7A and the second wavelength converter 8A. Therefore, the light-emitting device can also become a high-output point light source, expanding the industrial applications of solid-state lighting.

[0085] Such laser diodes can be, for example, edge-emitting lasers (EELs) or vertical cavity surface-emitting lasers (VCSELs).

[0086] Furthermore, by incorporating light-guiding components such as optical fibers, a structure can be formed in which at least one of the first light-emitting element 5 and the second light-emitting element 6, and at least one of the first wavelength converter 7A and the second wavelength converter 8A, are spatially separated. This results in a light-emitting device in which the light-emitting part can be moved easily and freely, and the illumination location can be easily changed.

[0087] The light energy density of the first primary ray 1A emitted by the first light-emitting element 5 is preferably greater than 0.3 W / mm². 2 More preferably, it exceeds 1.0W / mm 2 Furthermore, the light energy density of the second primary light 2A emitted by the second light-emitting element 6 is preferably greater than 0.3 W / mm². 2 More preferably, it exceeds 1.0W / mm 2In this case, the light energy density of the first primary light 1A and the second primary light 2A is high. Therefore, this becomes a light-emitting device that emits relatively strong output light 9 even when the structure of irradiating the first wavelength converter 7A and the second wavelength converter 8A after light diffusion is adopted. Furthermore, this becomes a light-emitting device that emits output light 9 with high light energy density if the structure of irradiating the first wavelength converter 7A and the second wavelength converter 8A without light diffusion is adopted.

[0088] There is no particular upper limit to the light energy density of the first primary light 1A emitted by the first light-emitting element 5 and the second primary light 2A emitted by the second light-emitting element 6. For example, it can be set to 30W / mm². 2 .

[0089] As described above, in the light-emitting device 10, the first light-emitting element 5 and the second light-emitting element 6 are preferably solid-state light-emitting elements, and preferably at least one of a light-emitting diode and a laser diode. However, the first light-emitting element 5 and the second light-emitting element 6 are not limited to these; any light-emitting element can be used as long as it can emit high-output first primary light 1A and second primary light 2A.

[0090] At least one of the first light-emitting element 5 and the second light-emitting element 6 preferably employs a structure comprising multiple solid-state light-emitting elements. This facilitates increasing the output of the first primary light 1A and the second primary light 2A, thus creating a light-emitting device that is advantageous for high output. Furthermore, the number of solid-state light-emitting elements is not particularly limited; for example, it can be 9 or more, 16 or more, 25 or more, 36 or more, 49 or more, 64 or more, 81 or more, or 100 or more. Moreover, the upper limit of the number of solid-state light-emitting elements is not particularly limited; for example, it can be 9, 16, 25, 36, 49, 64, 81 or 100.

[0091] In the light-emitting device 10, at least one of the first light-emitting element 5 and the second light-emitting element 6 is preferably a surface-emitting type light source. Furthermore, it is preferable that both the first light-emitting element 5 and the second light-emitting element 6 are surface-emitting type light sources. This allows for the suppression of deviations in the intensity distribution and unevenness in the color tone of the first primary light 1A and the second primary light 2A irradiated onto the wavelength converter. Therefore, it becomes a light-emitting device capable of suppressing deviations in the intensity distribution and unevenness in the color tone of the output light 9.

[0092] (First wavelength converter, second wavelength converter)

[0093] In the light-emitting device 10 of this embodiment, the first wavelength converter 7A can be manufactured by sealing at least the first phosphor 7 with a sealing fastener. Furthermore, the second wavelength converter 8A can be manufactured by sealing at least the second phosphor 8 with a sealing fastener. The sealing fastener is preferably at least one of an organic material and an inorganic material, and particularly preferably at least one of a transparent (transparent) organic material and a transparent (transparent) inorganic material. Examples of organic materials used as sealing fasteners include transparent organic materials such as silicone resin. Examples of inorganic materials used as sealing fasteners include transparent inorganic materials such as low-melting-point glass.

[0094] Furthermore, the first wavelength converter 7A can be fabricated using adhesives or the like, making it an entirely inorganic wavelength converter with a first phosphor as its main component. Moreover, by sintering the first phosphor, the first wavelength converter 7A can also be fabricated as a sintered body of inorganic material, i.e., a fluorescent ceramic. Similarly, the second wavelength converter 8A can be fabricated using adhesives or the like, making it an entirely inorganic wavelength converter with a second phosphor as its main component. Furthermore, by sintering the second phosphor, the second wavelength converter 8A can also be fabricated as a sintered body of inorganic material, particularly a fluorescent ceramic. Furthermore, such wavelength converters and fluorescent ceramics can be appropriately composited. For example, the wavelength converter and fluorescent ceramic can be laminated together.

[0095] Resin-encapsulated wavelength converters are advantageous in providing relatively inexpensive light-emitting devices because they can be easily manufactured using powder phosphors. Furthermore, the excellent thermal conductivity of all-inorganic wavelength converters simplifies the heat dissipation design of the light-emitting device. Therefore, the temperature rise of the wavelength converter can be suppressed, reducing thermal extinction of the phosphor, thus making it a favorable light-emitting device for high output.

[0096] The thickness of the first wavelength converter 7A and the second wavelength converter 8A is not particularly limited. However, by way of example, the maximum thickness of the first wavelength converter 7A and the second wavelength converter 8A is preferably 100 μm or more and less than 5 mm, and more preferably 200 μm or more and less than 1 mm.

[0097] Preferably, the first wavelength converter 7A is configured to completely cover the light output surface of the first light-emitting element 5. More preferably, the first light-emitting element 5 is a surface-emitting light source, and the first wavelength converter 7A is configured to completely cover the light output surface of this surface-emitting light source. Similarly, the second wavelength converter 8A is preferably configured to completely cover the light output surface of the second light-emitting element 6. More preferably, the second light-emitting element 6 is a surface-emitting light source, and the second wavelength converter 8A is configured to completely cover the light output surface of this surface-emitting light source. This results in a structure where the first primary light 1A efficiently illuminates the first wavelength converter 7A. Similarly, it results in a structure where the second primary light 2A efficiently illuminates the second wavelength converter 8A. Therefore, the conversion efficiency of the first primary light 1A and the second primary light 2A is increased, resulting in a high-efficiency light-emitting device 10.

[0098] Furthermore, the first wavelength converter 7A and the second wavelength converter 8A are preferably transparent. This allows for the effective output of the light component generated by wavelength conversion within the wavelength converter, making it a light-emitting device that facilitates high output.

[0099] (First fluorescent agent)

[0100] The first phosphor 7 is a phosphor that absorbs at least a portion of the first primary light 1A emitted by the first light-emitting element 5 and converts it into first wavelength-converted light 3A. For example, various inorganic phosphors known for use in solid-state lighting sources can be used as the first phosphor 7.

[0101] For example, if a phosphor that emits blue wavelength-converted light with the maximum fluorescence intensity in the wavelength range of 435 nm to 500 nm is used as the first phosphor 7, then the output light 9 contains a blue light component. In this case, light with a wavelength of 380 nm or more and exhibiting the maximum intensity in the range of wavelengths shorter than the wavelength exhibiting the aforementioned maximum fluorescence intensity can be used as the first primary light 1A.

[0102] For example, if a phosphor that emits blue-green or green wavelength-converted light that exhibits maximum fluorescence intensity in a wavelength range of 470 nm or higher and less than 530 nm is used as the first phosphor 7, then the output light 9 contains a blue-green light component. In this case, light with a wavelength of 380 nm or higher and exhibiting maximum intensity in a range less than the wavelength exhibiting the aforementioned maximum fluorescence intensity can be used as the first primary light 1A.

[0103] For example, if a phosphor emitting green or yellowish-green wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 500 nm or higher and less than 560 nm is used as the first phosphor 7, then the output light 9 contains a green light component. In this case, light exhibiting maximum intensity in a wavelength range of 380 nm or higher and less than the wavelength exhibiting the aforementioned maximum fluorescence intensity can be used as the first primary light 1A. Furthermore, light exhibiting maximum intensity in a wavelength range of 435 nm or higher and less than 500 nm is preferred as the first primary light 1A.

[0104] For example, if a phosphor emitting yellow or orange wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 560 nm or higher and less than 600 nm is used as the first phosphor 7, then the output light 9 contains a yellow light component. In this case, light exhibiting maximum intensity in a wavelength range of 380 nm or higher and less than the wavelength exhibiting the aforementioned maximum fluorescence intensity can be used as the first primary light 1A. Furthermore, light exhibiting maximum intensity in a wavelength range of 435 nm or higher and less than 500 nm, or 500 nm or higher and less than 560 nm, is preferred as the first primary light 1A.

[0105] For example, if a phosphor emitting red or deep red wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 600 nm to 700 nm, particularly 610 nm to 660 nm, is used as the first phosphor 7, then the output light 9 contains a red light component. In this case, light exhibiting maximum intensity in a wavelength range of 380 nm or higher, and particularly in a wavelength range shorter than the wavelength exhibiting the aforementioned maximum fluorescence intensity, can be used as the first primary light 1A. Furthermore, light exhibiting maximum intensity in a wavelength range of 435 nm to 500 nm, 500 nm to 560 nm, or 560 nm to 600 nm is preferred as the first primary light 1A.

[0106] Furthermore, if a phosphor that emits wavelength-modulated light containing a blue-green light component that is highly visible when observed in the dark is used as the first phosphor 7, then it becomes a light-emitting device 10 that emits output light 9 that is easily identifiable in the dark or in darkness. Additionally, if a phosphor that emits wavelength-modulated light containing a green light component that is highly visible when observed in the bright is used as the first phosphor 7, then it becomes a light-emitting device 10 that emits output light 9 that is easily identifiable in bright light.

[0107] If a phosphor that emits wavelength-changing light containing a yellow light component is used as the first phosphor 7, it becomes a light-emitting device 10 that is advantageous, for example, in working environments using resins that are easily sensitive to ultraviolet or blue light. Furthermore, if a phosphor that emits wavelength-changing light containing a red light component is used as the first phosphor 7, it becomes a light-emitting device 10 that emits output light 9 that improves the appearance of edible meat, tuna, apples, or human skin.

[0108] As the first phosphor 7, a phosphor that emits visible fluorescence upon activation by at least one of rare earth ions and transition metal ions can be used. Ce is the preferred rare earth ion. 3+ and Eu 2+ Of at least one, the transition metal ion is particularly preferred to be Mn. 4+ Furthermore, as the first phosphor 7, a phosphor containing the aforementioned ions as the luminescent center and containing at least one of oxides, sulfides, nitrides, halides, sulfur oxides, nitrogen oxides, and acyl halides as the parent material can be used.

[0109] More specifically, the phosphor that can be used as the first phosphor 7 is preferably at least one selected from the group consisting of halophosphates, phosphates, halosilicates, silicates, aluminates, aluminosilicates, borates, germanates, silicates nitrides, aluminum silicates nitrides, silicates oxynitrides, and aluminum silicates oxynitrides. Furthermore, the first phosphor 7 may be selected from these compounds as long as they are suitable for the lighting design.

[0110] The phosphor particularly preferred as the first phosphor 7 is one with a garnet-type crystal structure and is coated with Ce. 3+ Activated composite oxide phosphors. Such Ce 3+ Rare-earth aluminum garnet phospholipids are preferred for activating garnet phospholipids. Specifically, Ce... 3+ The preferred activator for garnet phosphors is Lu3Al2(AlO4)3:Ce 3+ Y3Al2(AlO4)3:Ce 3+ Lu3Ga2(AlO4)3:Ce 3+ Y3Ga2(AlO4)3:Ce 3+ At least one selected from the group comprising the constituent elements. Furthermore, Ce 3+ Activating garnet fluorophores is also preferably achieved by using these fluorophores as solid solutions of end-member components.

[0111] Ce 3+Most activated garnet phosphors possess the property of absorbing blue light and converting it into green light. Therefore, as the first light-emitting element 5 that emits the first primary light 1A, a solid-state light-emitting element that emits blue light can be used. Thus, it is possible to obtain output light 9 that contains at least two light components, blue and green, and has high color rendering.

[0112] Furthermore, with the development of automotive headlight technology and high-output projector technology, in recent years, Ce has become increasingly important in ensuring high output and reliability. 3+ The ceramicization technology for activating garnet phosphors is also under development. Therefore, it is also easy to provide a light-emitting device 10 that uses fluorescent ceramics and is advantageous in terms of high output and reliability.

[0113] (Second fluorescent agent)

[0114] The second phosphor 8 is a phosphor that absorbs and converts at least one of the first primary light 1A emitted by the first light-emitting element 5 and the second primary light 2A emitted by the second light-emitting element 6 into a second wavelength-converted light 4A. In this case, the second phosphor 8 absorbs at least a portion of the irradiated primary light. Furthermore, the second phosphor 8 is preferably a phosphor that absorbs and converts the second primary light 2A emitted by the second light-emitting element 6 into the second wavelength-converted light 4A. For example, various inorganic phosphors known for use in near-infrared light sources can be used as the second phosphor 8.

[0115] For example, if a phosphor that emits near-infrared wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 700 nm to 1700 nm is used as the second phosphor 8, the output light 9 can contain light components of absorption wavelengths of various gas molecules. In this case, light exhibiting maximum intensity in a wavelength range of 380 nm to 700 nm can be used as the primary absorbed light. Furthermore, as this primary light, it is preferable to use green to yellow light exhibiting maximum intensity in a wavelength range of 500 nm to 580 nm, or red light exhibiting maximum intensity in a wavelength range of 600 nm to 680 nm.

[0116] In addition, the absorption wavelengths of various gas molecules are as follows: O2 is 760nm, NO2 is 830nm, H2O is 1365nm, NH3 is 1530nm, C2H2 is 1530nm, CO is 1567nm, CO2 is 1573nm, and CH4 is 1651nm.

[0117] Here, near-infrared spectroscopy can be used to obtain information about oxygen (O2), nitrogen dioxide (NO2), and objects containing these components. Furthermore, the second phosphor 8 used for this purpose is preferably a phosphor that emits wavelength-converted light that exhibits maximum fluorescence intensity in a wavelength range exceeding 700 nm and less than 900 nm, and more preferably in a wavelength range exceeding 750 nm and less than 850 nm.

[0118] Near-infrared spectroscopy can be used to obtain information about water (H2O) and water-containing objects. Furthermore, the second phosphor 8 used for this purpose is preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range exceeding 1200 nm and less than 1500 nm, and more preferably in a wavelength range exceeding 1275 nm and less than 1425 nm.

[0119] Near-infrared spectroscopy can be used to obtain information about ammonia (NH3), hydrocarbons (C2H2, CH4, etc.), carbon oxides (CO, CO2, etc.), and substances containing these components. Furthermore, the second phosphor 8 used for this purpose is preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range exceeding 1400 nm and less than 1800 nm, and more preferably in a wavelength range exceeding 1500 nm and less than 1700 nm.

[0120] Conversely, sometimes the absorption of the second wavelength-converted light 4A emitted from the second phosphor 8 by oxygen or nitrogen dioxide can have adverse effects on objects or systems. In this case, it is preferable to use a phosphor 8 whose maximum intensity in a wavelength range exceeding 750 nm and less than 850 nm is less than 10% of the maximum intensity in a wavelength range exceeding 700 nm and less than 1700 nm. Furthermore, it is preferable to use a phosphor 8 whose maximum intensity in a wavelength range exceeding 700 nm and less than 900 nm is less than 10% of the maximum intensity in a wavelength range exceeding 700 nm and less than 1700 nm. Moreover, it is more preferable to use a phosphor 8 that does not have a light component in the aforementioned wavelength ranges.

[0121] Furthermore, the absorption of the second wavelength-converted light 4A emitted from the second phosphor 8 by water can sometimes have adverse effects on objects or systems. In such cases, it is preferable to use a phosphor 8 whose maximum intensity value in a wavelength range exceeding 1275 nm and less than 1425 nm is less than 10% of the maximum intensity value in a wavelength range exceeding 700 nm and less than 1700 nm. Furthermore, it is preferable to use a phosphor 8 whose maximum intensity value in a wavelength range exceeding 1200 nm and less than 1500 nm is less than 10% of the maximum intensity value in a wavelength range exceeding 700 nm and less than 1700 nm. Moreover, it is preferable to use a phosphor 8 that does not have a light component in the aforementioned wavelength ranges.

[0122] Sometimes, the second wavelength-converted light 4A emitted from the second phosphor 8 can be absorbed by ammonia, hydrocarbons, or carbon oxides, causing adverse effects on objects or systems. In such cases, it is preferable to use a phosphor 8 whose maximum intensity value in a wavelength range exceeding 1500 nm and less than 1700 nm is less than 10% of the maximum intensity value in a wavelength range exceeding 700 nm and less than 1700 nm. Furthermore, it is preferable to use a phosphor 8 whose maximum intensity value in a wavelength range exceeding 1400 nm and less than 1800 nm is less than 10% of the maximum intensity value in a wavelength range exceeding 700 nm and less than 1700 nm. Moreover, it is preferable to use a phosphor 8 that does not have a light component in the aforementioned wavelength ranges.

[0123] Furthermore, the light-emitting device 8, which uses a phosphor that emits near-infrared wavelength-converting light as the second phosphor, outputs a light component with high spectroscopic sensitivity from the photodiode. Moreover, photodiodes are specifically designed for use as sensors in detectors. Therefore, such a light-emitting device can be appropriately used in inspection devices that utilize photodiodes.

[0124] For example, in the case of an inspection device using a Si photodiode or a Si-PIN photodiode, the second phosphor 8 is preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 700 nm or higher and less than 1100 nm. Furthermore, in this case, the second phosphor 8 is more preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 780 nm or higher and less than 1050 nm, particularly in a wavelength range of 800 nm or higher and less than 1000 nm.

[0125] For example, in the case of an inspection device using a Ge photodiode, the second phosphor 8 is preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 700 nm or higher and less than 1600 nm. Furthermore, in this case, the second phosphor 8 is more preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 1100 nm or higher and less than 1550 nm, particularly in a wavelength range of 1300 nm or higher and less than 1500 nm.

[0126] For example, in the case of an inspection device using an InGaAs photodiode, the second phosphor 8 is preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 900 nm or higher and less than 1650 nm. Furthermore, in this case, the second phosphor 8 is more preferably a phosphor that emits wavelength-converted light exhibiting maximum fluorescence intensity in a wavelength range of 1000 nm or higher and less than 1600 nm, particularly in a wavelength range of 1100 nm or higher and less than 1600 nm.

[0127] Furthermore, the likelihood of a light-emitting device using a phosphor that emits near-infrared light at a relatively short wavelength as the second phosphor 8 to output light components with wavelengths above 4000 nm as heat rays is low. Therefore, such a light-emitting device is suitable for inspecting objects that are easily degraded by heat.

[0128] On the other hand, as the second phosphor 8, a near-infrared phosphor that emits near-infrared light on the longer wavelength side, exhibiting maximum fluorescence intensity in a wavelength range of 780 nm to 2500 nm, preferably 800 nm to 2500 nm, can also be used. Thus, the output light 9 can include an infrared light component invisible to the human eye. Furthermore, as the primary light to be absorbed, light exhibiting maximum intensity in a visible wavelength range of 380 nm to 700 nm can be used.

[0129] Such a light-emitting device, which uses a phosphor that emits near-infrared light at a relatively long wavelength, is less likely to output a visible light component with a wavelength shorter than 780 nm, which is visible to the human eye. Therefore, such a light-emitting device can be preferably used for monitoring where the presence of the output light 9 is inconvenient to be noticed by humans.

[0130] As the second phosphor 8, a phosphor that is activated by at least one of rare earth ions and transition metal ions and emits fluorescence containing near-infrared light components can be used. The rare earth ions are preferably derived from Nd... 3+ Eu 2+ Ho 3+ Er 3+ Tm 3 + and Yb 3+At least one selected from the group consisting of [components]. The transition metal ions are preferably from Ti [components]. 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 group comprising the first phosphor 7. Furthermore, similarly to the first phosphor 7, the second phosphor 8 may use a phosphor containing the aforementioned ions as the luminescent center and containing at least one of oxides, sulfides, nitrides, halides, sulfur oxides, nitrogen oxides, and acyl halides as the parent phosphor.

[0131] Furthermore, the ion that functions as a fluorescent ion in the second phosphor 8 can be at least one of the aforementioned rare earth ions and transition metal ions. Moreover, it is sufficient for the fluorescent ion to possess the property of absorbing at least one of the first primary light 1A and the second primary light 2A and converting it into a near-infrared light component. However, a preferred fluorescent ion is Cr. 3+ That is, the second phosphor 8 is preferably one containing Cr. 3+ As a fluorescent ion.

[0132] By using Cr 3+ As fluorescent ions, second phosphors 8 readily acquire the property of absorbing visible light, particularly blue or red light, and converting it into near-infrared light components. Furthermore, depending on the parent compound, the wavelengths of the light absorption peak and fluorescence peak can be easily altered, becoming advantageous in changing the shape of the excitation spectrum and the fluorescence spectrum. Moreover, many Cr-containing fluorescent compounds are known to absorb blue and red light and convert it into near-infrared fluorescent components. 3+ The phosphor is activated. Therefore, not only is the range of selection for the first light-emitting element 5 and the second light-emitting element 6 increased, but it is also easier to change the fluorescence peak wavelength of the second wavelength-converted light 4A emitted by the second phosphor 8, which is beneficial for controlling the spectral distribution of the output light.

[0133] In addition, the fluorescent ion is Cr 3+ The type of phosphor is not particularly limited as long as it absorbs and converts at least one of the first primary light 1A and the second primary light 2A into an infrared fluorescent component. However, as a Cr 3+ Activated phosphors can be exemplified by easily manufactured composite metal oxides.

[0134] The phosphor particularly preferred as the second phosphor 8 is one with a garnet-type crystal structure and coated with Cr. 3+Activated composite oxide phosphors. Such Cr... 3+ The preferred activator for garnet phosphors is at least one of rare-earth aluminum garnet phosphors and rare-earth gallium garnet phosphors. Specifically, Cr 3+ The preferred active material for activating garnet fluorophores 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+ (Gd,La)3Ga2(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 (Gd,La)3(Ga,Sc)2(GaO4)3:Cr 3+ At least one selected from the group comprising the constituent elements. Furthermore, Cr 3+ Activating garnet fluorophores can also be achieved by using solid solutions of these fluorophores as end-member components.

[0135] Such phosphors can be synthesized using traditional solid-state reactions. For example, they can be synthesized by calcining a mixture of powders of various metal oxides containing the constituent elements of phosphors (rare earth elements, Al, Ga, Cr, etc.) at around 1600°C.

[0136] In addition, for example, by (Gd 0.75 La 0.25 )3(Ga 0.5 Sc 0.47 Cr 0.03 The composition of (Gd,La)3(Ga,Sc)2(GaO4)3 is represented by the formula (Gd,La)3(Ga,Sc)2(GaO4)3:Cr 3+The phosphor exhibits excitation spectral peaks near 460 nm and 640 nm. Furthermore, it can absorb and convert light at these wavelengths into a light component with a fluorescence peak near 780 nm. Additionally, this phosphor can absorb light near 460 nm and 640 nm with an absorption rate exceeding 60%, thereby enabling wavelength conversion with a high photon conversion efficiency of approximately 90%.

[0137] Cr 3+ Most activated garnet phosphors possess the property of absorbing blue or red light and converting it into deep red to near-infrared light. Therefore, as the first light-emitting element 5 and / or the second light-emitting element 6, solid-state light-emitting elements that emit blue light and / or red light can be used. This allows for the generation of output light 9 containing at least one (blue or red) light component of the three primary colors of light (blue, green, and red) and a near-infrared light component.

[0138] Specifically, the first light-emitting element 5, which emits the first primary light 1A, is a solid-state light-emitting element that emits blue light, and the second light-emitting element 6, which emits the second primary light 2A, is a solid-state light-emitting element that emits red light. Furthermore, the first phosphor 7, which emits the first wavelength-converted light 3A, is a Ce-type phosphor that converts the blue light emitted by the first light-emitting element 5 into green light. 3+ Activate the garnet phosphor. Furthermore, the second phosphor 8, which emits a second wavelength-converted light 4A, is a Cr phosphor that converts the red light emitted by the second light-emitting element 6 into near-infrared light. 3+ Activate the garnet phosphor. With this structure, a light-emitting device 10 can be made that can easily produce output light 9 with high color rendering, containing light components of the three primary colors (blue, green, and red) that constitute light and near-infrared light components.

[0139] In addition, Ce 3+ Materials technologies for activating garnet phosphors, including ceramicization techniques, are under development. Therefore, it is also easy to use Ce... 3+ The technology developed to activate garnet phosphors is applied to Cr 3+ Activate the garnet fluorophore. Furthermore, if Cr is used... 3+ Activating fluorescent ceramics with garnet phosphors as the main body becomes advantageous in terms of high output of near-infrared light components (fourth light component 4) and device reliability.

[0140] Furthermore, regarding Ce 3+ There are various types of activated garnet fluorophores, making the preparation of these correlation techniques relatively easy. Therefore, by using Ce... 3+ The technology level for activating garnet phosphors has been expanded to include Cr. 3+Activating garnet phosphors can effectively develop desired light-emitting devices.

[0141] (The operation of the light-emitting device)

[0142] use Figures 2 to 6 The operation of the light-emitting device 10 in this embodiment will be explained. First, if power is supplied to the first light-emitting element 5 and the second light-emitting element 6, the first light-emitting element 5 emits a first primary light 1A, and the second light-emitting element emits a second primary light 2A.

[0143] If the first primary light 1A emitted from the first light-emitting element 5 is incident on the first wavelength converter 7A, the first wavelength converter 7A absorbs a portion of the first primary light 1A and emits a first wavelength converted light 3A with lower energy. On the other hand, if the second primary light 2A emitted from the second light-emitting element 6 is incident on the second wavelength converter 8A, the second wavelength converter 8A absorbs a portion of the second primary light 2A and emits a second wavelength converted light 4A with lower energy.

[0144] The first primary light 1A, the second primary light 2A, the first wavelength-converted light 3A, and the second wavelength-converted light 4A generated in this way become the sources of the first light component 1, the second light component 2, the third light component 3, and the fourth light component, respectively. Furthermore, these light components form a spectral distribution and are output as the output light 9.

[0145] (Basic structure of a light-emitting device)

[0146] exist Figures 2 to 6 In the illustrated light-emitting device, the first primary light 1A can be, for example, blue light emitted by a solid-state light-emitting element. The second primary light 2A can be, for example, red light emitted by a solid-state light-emitting element. The first wavelength-converted light 3A can be, for example, green light obtained by wavelength conversion of blue light using a first phosphor 7. The second wavelength-converted light 4A can be, for example, near-infrared light obtained by wavelength conversion of red light using a second phosphor 8.

[0147] In this structure, the first light-emitting element 5 can be a solid-state light-emitting element that emits blue light with a peak in the wavelength range of 430 nm to less than 480 nm, preferably 440 nm to less than 470 nm, as a first primary light 1A. The second light-emitting element 6 can be a solid-state light-emitting element that emits red light with a fluorescence peak in the wavelength range of 600 nm to less than 680 nm, preferably 610 nm to less than 660 nm, as a second primary light 2A. The first phosphor 7 can be a phosphor that absorbs blue light and converts it into green light as a first wavelength-converted light 3A, and can be a phosphor that is Ce-treated. 3+ Or Eu 2+ Activated phosphors, especially Ce 3+Activate the garnet phosphoenix. The second phosphoenix 8 can be a phosphoenix that absorbs and converts blue and / or red light into near-infrared light as the second wavelength conversion light 4A, and can be a phosphoenix activated by transition metal ions, especially Cr. 3+ Activate garnet fluorophores.

[0148] Furthermore, the second light-emitting element 6, tailored to the application, can be a solid-state light-emitting element that emits light of other colors, instead of a solid-state light-emitting element that emits red light. Specifically, the second light-emitting element 6 can also be a solid-state light-emitting element that emits green light with a fluorescence peak in the wavelength range of 500 nm to 560 nm, preferably 510 nm to 550 nm. Alternatively, the second light-emitting element 6 can also be a solid-state light-emitting element that emits yellow or orange light with a fluorescence peak in the wavelength range of 560 nm to 600 nm, preferably 575 nm to 600 nm.

[0149] If such a structure is adopted, the output light 9, composed of the first light component 1, the second light component 2, the third light component 3, and the fourth light component, will have both visible and near-infrared light components. Furthermore, the fluorescence intensity near the boundary between the visible and near-infrared light of the output light 9 decreases, resulting in a spectral distribution with a certain degree of clarity in which they are separated.

[0150] Furthermore, the hue of the first primary light 1A, which is the source of the first light component 1, and the hue of the second primary light 2A, which is the source of the second light component 2, can be changed by altering the types of the first light-emitting element 5 and the second light-emitting element 6, respectively. Similarly, the hue of the first wavelength-converted light 3A, which is the source of the third light component 3, and the hue of the second wavelength-converted light 4A, which is the source of the fourth light component 4, can be changed by altering the types of the first wavelength converter 7A and the second wavelength converter 8A, respectively. Moreover, the output ratio of each light component can be changed by altering the power ratio supplied to the first light-emitting element 5 and the second light-emitting element 6, the thickness of the first wavelength converter 7A and the second wavelength converter 8A, or the phosphor concentration. Therefore, with such a structure, the control of the spectral distribution of the output light 9 becomes easy.

[0151] Furthermore, the wavelength converter including the second phosphor is preferably designed to transmit the fourth light component 4. That is, the second wavelength converter 8A including the second phosphor 8 preferably has the characteristic of transmitting the second wavelength-converted light 4A, which is the source of the fourth light component 4. In this case, the second wavelength converter 8A transmits the near-infrared light component, suppressing photons from being absorbed and disappearing within the wavelength converter itself. Therefore, it becomes a light-emitting device that facilitates high output of near-infrared light.

[0152] like Figure 2As shown, the light-emitting device 10 can also be a structure using a first wavelength-converting light-emitting element composed of a first light-emitting element 5 and a first wavelength converter 7A, and a second wavelength-converting light-emitting element composed of a second light-emitting element 6 and a second wavelength converter 8A. In this case, by pre-planning and designing the first and second wavelength-converting light-emitting elements to emit light of different hues, the hue of the output light 9 can be controlled simply by their combination. Therefore, it becomes a light-emitting device that is advantageous in meeting customer expectations.

[0153] like Figure 3 As shown, the light-emitting device 10 can also be a structure in which a first wavelength converter 7A and a second wavelength converter 8A are integrated, and a first primary light 1A emitted by the first light-emitting element 5 and a second primary light 2A emitted by the second light-emitting element 6 are both irradiated by a single wavelength converter. In this case, the hue of the output light 9 can be controlled by changing the ratio of the first phosphor 7 to the second phosphor 8 contained in the wavelength converter. Furthermore, the hue of the output light 9 can be controlled simply by changing the ratio of the number of the first light-emitting element 5 and the second light-emitting element 6. Moreover, by pre-planning and designing wavelength converters, first light-emitting elements 5, and second light-emitting elements 6 to emit light of different hues, the hue of the output light 9 can be controlled simply by their combination. Therefore, this becomes a light-emitting device that is advantageous in meeting customer expectations.

[0154] like Figure 4 As shown, the light-emitting device 10 can also be a structure using a first wavelength-converting type light-emitting element, a second light-emitting element 6, and a second wavelength-converting element 8A, which are formed by combining a first light-emitting element 5 and a first wavelength-converting element 7A. In this case, it becomes a structure that illuminates the second wavelength-converting element 8A in both directions with the first primary light 1A and the second primary light 2A transmitted through the first wavelength-converting element 7A. If this is the case, by preparing in advance the first wavelength-converting type light-emitting element, the second light-emitting element 6, and the second wavelength-converting element 8A designed to emit light of different hues, the hue of the output light 9 can be controlled simply by their combination. Therefore, it becomes a light-emitting device that is advantageous in meeting the needs of customers.

[0155] like Figure 5As shown, the light-emitting device 10 can also be a structure using a first light-emitting element 5, a second light-emitting element 6, a first wavelength converter 7A, and a second wavelength converter 8A, which are prepared in advance. In this case, it becomes a structure that irradiates the first wavelength converter 7A with both the first primary light 1A and the second primary light 2A, and then irradiates the second wavelength converter 8A with both the first primary light 1A and the second primary light 2A that have been transmitted through the first wavelength converter 7A. If this is the case, by preparing in advance the first light-emitting element 5, the second light-emitting element 6, the first wavelength converter 7A, and the second wavelength converter 8A designed to emit light of different hues, the hue of the output light 9 can be controlled simply by their combination. Therefore, it becomes a light-emitting device that is advantageous in meeting the needs of customers.

[0156] like Figure 6 As shown, the light-emitting device 10 can also be structured using a first light-emitting element 5, a second light-emitting element 6, a first wavelength converter 7A, and a second wavelength converter 8A, which are prepared in advance. In this case, the first primary light 1A illuminates only the first wavelength converter 7A, and the second primary light 2A illuminates only the second wavelength converter 8A. Thus, by pre-preparing and designing the first light-emitting element 5, the second light-emitting element 6, the first wavelength converter 7A, and the second wavelength converter 8A to emit light of different hues, the hue of the output light 9 can be controlled simply by their combination. Therefore, it becomes a light-emitting device that is advantageous in meeting the needs of customers.

[0157] like Figures 3 to 6 As shown, the light-emitting device 10 can be a transmissive structure in which the first primary light 1A and the second primary light 2A are received on the front sides (7Aa, 8Aa) of the first wavelength converter 7A and the second wavelength converter 8A, and fluorescence is emitted from the back sides (7Ab, 8Ab). Alternatively, it can be a reflective structure in which the first primary light 1A and the second primary light 2A are received on the front sides (7Aa, 8Aa) of the first wavelength converter 7A and the second wavelength converter 8A, and fluorescence is emitted from the same front sides (7Aa, 8Aa).

[0158] like Figures 3 to 5 As shown, the light-emitting device 10 of this embodiment can be a structure in which a mixed light component of the first light component 1 and the third light component, as well as a mixed light component of the second light component and the fourth light component, are output from the same output surface. In this case, light components that do not contain near-infrared light and light components that contain near-infrared light are output from the same light output surface, thus becoming a light-emitting device that is conducive to miniaturization of the light output surface.

[0159] More specifically, in the light-emitting device 10, the first primary light 1A emitted by the first light-emitting element 5 and the second primary light 2A emitted by the second light-emitting element 6 both irradiate the first wavelength converter 7A or the second wavelength converter 8A. Furthermore, as... Figures 3 to 5 As shown, the configuration can be such that the mixed light component of the first light component 1 and the third light component, as well as the mixed light component of the second light component and the fourth light component, are output from the same output surface. Furthermore, to achieve such a structure, it is preferable that both the first wavelength converter 7A and the second wavelength converter 8A have light transmittance. That is, it is preferable that both the first primary light 1A and the second primary light 2A transmit through the first wavelength converter 7A and / or the second wavelength converter 8A, enabling the output of the first wavelength converted light 3A and the second wavelength converted light 4A together.

[0160] If the light-emitting device 10 is made Figures 3 to 5 Such a structure allows the size of the light output surface 9 to be contained within the area of ​​the larger of the first wavelength converter 7A and the second wavelength converter 8A. Therefore, it becomes a light-emitting device that is advantageous for miniaturization.

[0161] exist Figure 5 In the light-emitting device 10, a first wavelength converter 7A is disposed on the side close to the first light-emitting element 5 and the second light-emitting element 6, and a second wavelength converter 8A is disposed on the side away from them. However, it is also possible to dispose of the second wavelength converter 8A on the side close to the first light-emitting element 5 and the second light-emitting element 6, and to dispose of the first wavelength converter 7A on the side away from them.

[0162] like Figure 2 and Figure 6 As shown, the light-emitting device 10 of this embodiment can be a structure that illuminates the first wavelength converter 7A without illuminating the second wavelength converter 8A, and outputs both the first primary light 1A and the first wavelength converted light 3A. Alternatively, it can be a structure that illuminates the second wavelength converter 8A without illuminating the first wavelength converter 7A, and outputs both the second primary light 2A and the second wavelength converted light 4A. In this case, the mixed light components of the first light component 1 and the third light component 3, and the mixed light components of the second light component 2 and the fourth light component 4, are output from mutually different output surfaces.

[0163] in the case of Figure 2 and Figure 6 Such a structure independently possesses a light-emitting surface that emits a fourth light component 4, including near-infrared light, and a light-emitting surface that emits visible light without near-infrared light. Furthermore, the output light without near-infrared light and the output light containing near-infrared light are emitted separately. Therefore, these output lights can be controlled independently, and the intensity ratio of near-infrared and visible light, as well as the hue of the visible light, can be controlled according to the application. In addition, near-infrared and visible light can be emitted alternately.

[0164] For example, a light-emitting device that alternately illuminates near-infrared and visible light can further suppress interference between reflected near-infrared and visible light in the detector. Therefore, by using this light-emitting device, an electronic device that can obtain a signal with a good signal-to-noise ratio can be provided.

[0165] (An example of an improved light-emitting device)

[0166] Next, regarding the light-emitting device of this embodiment, an improved example for improving performance will be described.

[0167] The light-emitting device 10 of this embodiment increases the absolute number of photons constituting the output light 9 by making the first light-emitting element 5 and the second light-emitting element 6 high-output elements or by increasing the number of light-emitting elements. As a result, the light energy of the output light 9 emitted from the light-emitting device 10 can exceed 3W, preferably exceeding 10W, and more preferably exceeding 30W. Furthermore, the light energy of the light component with a wavelength of 700nm or higher in the output light 9 can also exceed 3W. By employing such a high-output light-emitting device, stronger output light (e.g., near-infrared light) can be used for illumination, so even at a large distance from the irradiated object, relatively strong near-infrared radiation can be irradiated. Furthermore, even if the irradiated object is small or has a large thickness, information about the irradiated object can be obtained.

[0168] In the light-emitting device 10, it is preferable to supply photons that are converted into the fourth light component 4 by the second phosphor 8 from multiple solid-state light-emitting elements. This results in a structure that supplies more photons to the second phosphor 8, thus making the light-emitting device 10 conducive to high output of the near-infrared light component.

[0169] The light-emitting device 10 can also increase the photon density supplied to the phosphor by using the first light-emitting element 5 and the second light-emitting element 6 as light-emitting elements that emit high-density primary light, such as laser diodes, or by focusing the light emitted by the light-emitting elements with an optical lens. For example, it can make the light energy density of at least one of the first primary light 1A and the second primary light 2A, especially the second primary light 2A, exceed 0.3 W / mm². 2 Preferably, it exceeds 1.0W / mm 2 More preferably, it exceeds 3.0W / mm 2 If so, it becomes a light-emitting device capable of emitting output light 9 with high light energy density. Therefore, for example, it becomes a light-emitting device capable of point-outputting near-infrared light with high light energy density.

[0170] When using light-emitting elements that emit high-density light as the first light-emitting element 5 and the second light-emitting element 6, the light energy density of the primary light can exceed 0.3 W / mm². 2 Preferably, it exceeds 1.0W / mm2 More preferably, it exceeds 3.0W / mm 2 This results in a light-emitting device that emits relatively strong output light 9 even when the structure irradiates the first wavelength converter 7A and the second wavelength converter 8A with primary light that has been diffused. Furthermore, it also results in a light-emitting device that emits relatively strong output light 9 even when primary light that has not been diffused is irradiated with the first wavelength converter 7A and the second wavelength converter 8A. Therefore, it is possible to provide a light-emitting device that can irradiate a large area of ​​near-infrared light while using a light-emitting element with a small light output surface, or a light-emitting device that irradiates near-infrared light with a high light energy density.

[0171] Furthermore, by selecting an appropriate light-emitting element, the intensity of the light component in the output light 9 with a wavelength shorter than 440 nm can be adjusted to be less than 3% of the maximum fluorescence intensity. Additionally, the intensity of the light component in the output light 9 with a wavelength shorter than 440 nm can also be adjusted to be less than 1% of the maximum fluorescence intensity. In this way, the intensity of the light component in the ultraviolet to blue wavelength region, where photoresist is easily photosensitive, is close to zero. Therefore, this becomes a light-emitting device suitable for use in a yellow chamber, emitting near-infrared light that is beneficial for semiconductor correlation inspection operations.

[0172] Furthermore, in the light-emitting device of this embodiment, as described above, the first light-emitting element 5 and the second light-emitting element 6 are preferably light-emitting diodes (LEDs) or laser diodes (LDs). However, any light-emitting element can be used as long as the first light-emitting element 5 and the second light-emitting element 6 emit the first light component 1 and the second light component 2 respectively.

[0173] The light-emitting device of this embodiment may also include a light distribution control mechanism for controlling the light distribution characteristics. If such a structure is adopted, it becomes a light-emitting device capable of emitting output light with desired light distribution characteristics, such as a variable light distribution lighting system for vehicles.

[0174] The light-emitting device of this embodiment may also include a power supply control device or, for example, an output intensity variable mechanism to change the intensity of near-infrared radiation. With such a structure, it becomes a light-emitting device advantageous for inspecting foods or pharmaceuticals that are easily damaged by near-infrared radiation.

[0175] The light-emitting device of this embodiment may also include a variable mechanism for changing the peak wavelength of the light component with the maximum fluorescence intensity in a wavelength range of, for example, 700 nm or higher and less than 2500 nm. With such a structure, it becomes a highly versatile light-emitting device that can easily handle a wide variety of complex applications. Furthermore, since the penetration depth of light into the irradiated object varies according to the wavelength, it also becomes a light-emitting device advantageous for performing depth-direction inspections of the irradiated object. Additionally, such a variable fluorescence peak wavelength mechanism can be achieved using optical filters such as bandpass filters or low-frequency cutoff filters.

[0176] Furthermore, another method for changing the peak wavelength is as follows: First, the second wavelength converter 8A contains multiple second phosphors 8 with different fluorescence spectral shapes and excitation spectral shapes. Then, by exciting a particular second phosphor 8 with a first light-emitting element 5 or a second light-emitting element 6 that can be independently controlled, the peak wavelength can be changed.

[0177] The light-emitting device of this embodiment may also include a light control mechanism for ON-OFF control of at least a portion of the output light. This structure makes it a highly versatile light-emitting device that can easily handle a wide variety of complex applications.

[0178] The light-emitting device of this embodiment can set the visible light component with a wavelength less than 700 nm and / or the light component with a wavelength greater than 700 nm in the output light as pulsed light. Specifically, the light-emitting device can set the light component with a wavelength greater than 700 nm in the output light as pulsed light. The half-width of the pulsed light's illumination time can be set to less than 300 ms. Furthermore, the greater the output intensity of the output light 9 or the fourth light component 4, the shorter the half-width can be. Therefore, the half-width can be set to less than 100 ms, less than 30 ms, less than 10 ms, less than 3 ms, or less than 1 ms to match the output intensity of the output light 9 or the fourth light component 4. Additionally, the extinguishing time of the pulsed light can be set to more than 1 ms and less than 10 s.

[0179] Here, it is reported that the human eye perceives light at 50–100 Hz (period 20–10 ms) as flashes. Furthermore, it is reported that birds such as pigeons perceive light at around 150 Hz (period 6.7 ms) as flashes, and insects such as flies perceive light at around 300 Hz (period 3.3 ms) as flashes. Therefore, an extinction time of less than 30 ms, which these organisms do not perceive as flashes, is a preferred configuration.

[0180] On the other hand, strong light irradiation poses a risk of damaging the irradiated object. Therefore, in applications where flickering is not a concern, a pulse light extinguishing time of 100ms or more, especially 300ms or more, is preferred.

[0181] Furthermore, for cosmetic purposes involving the adjustment of human hair or body hair growth, the preferred light energy output is 0.01 J / cm². 2 Above and less than 1J / cm 2 Therefore, if the light energy of the output light emitted from the light-emitting device is set to this range and the output light is shone near the hair root, then melanin and other substances present in the skin can absorb the light, thereby regulating the growth of hair and the like.

[0182] Here, the preferred afterglow time of the output light, that is, the time when the light intensity drops to 1 / 10 before it is about to be extinguished, is preferably less than 100 μs, more preferably less than 10 μs, and particularly preferably less than 1 μs. Thus, a light-emitting device capable of instantaneous lighting and instantaneous extinguishing is achieved.

[0183] The light-emitting device of this embodiment may also include an ultraviolet light source that emits ultraviolet light with a maximum intensity in the wavelength range of 120 nm to less than 380 nm, preferably 250 nm to less than 370 nm. In this case, it becomes a light-emitting device that also has the bactericidal effect of ultraviolet light.

[0184] The light-emitting device of this embodiment may also include conventional lighting devices known in the past. In this case, it becomes a lighting device with the function of emitting near-infrared light. Alternatively, the lighting device can use a structure combining a solid-state light-emitting element and a phosphor. Specifically, examples include a blue LED and a Ce2+ phosphor as a green or yellow phosphor. 3+ Lighting devices composed of activated garnet phosphors. Additionally, examples include blue LEDs and CeO2 as green or yellow phosphors. 3+ Activated garnet fluorophore and Eu as a red fluorophore 2+ Activated nitride fluorophores or Eu 2+ An illumination device composed of activated nitrogen oxide phosphors.

[0185] The light-emitting device of this embodiment is preferably a medical light-emitting device. That is, the light-emitting device of this embodiment, which emits near-infrared light components, can be used as a light source or illumination device for medical or biotechnological purposes. In particular, the light-emitting device of this embodiment can be used as a medical light-emitting device in fluorescence imaging or photodynamic therapy, or as a biotechnological light-emitting device in the examination and analysis of cells, genes, and specimens. Since near-infrared light components have the property of penetrating living organisms and cells, such a light-emitting device allows for the observation and treatment of affected areas from both inside and outside the body, or can be utilized in biotechnology.

[0186] Furthermore, the light-emitting device of this embodiment, which emits near-infrared light components, can also serve as a light source or illumination system for a sensing system. Thus, for example, it is possible to inspect the contents or foreign objects in bags or containers made of organic materials in an unopened state using near-infrared light components that transmit through organic matter and near-infrared light components reflected by objects. Moreover, with such a light-emitting device, it is possible to monitor animals, plants, and objects, including humans.

[0187] Thus, the light-emitting device 10 of this embodiment is a light-emitting device that emits output light 9. The light-emitting device 10 includes: a first light-emitting element 5 that emits a first light component 1; a second light-emitting element 6, which, unlike the first light-emitting element 5, emits a second light component 2; a first phosphor 7 that emits a third light component 3; and a second phosphor 8, which, unlike the first phosphor 7, emits a fourth light component 4. The output light 9 includes the first light component 1, the second light component 2, the third light component 3, and the fourth light component 4, each with a different hue. The first light component 1 and the second light component 2 are visible light components that have a maximum intensity in a wavelength range of 380 nm or more and less than 700 nm. The third light component 3 is a visible light component derived from the first wavelength-converted light 3A emitted by the first phosphor 7, and has a maximum intensity in a wavelength range of 435 nm or more and less than 700 nm. The fourth light component 4 is a near-infrared light component derived from the second wavelength-converted light 4A emitted by the second phosphor 8, and has a maximum intensity in a wavelength range of 700 nm or more and less than 2500 nm. Furthermore, the output light 9 has a trough T in the wavelength range of 650nm and above to 750nm, and the minimum intensity in the wavelength range of 650nm and above to 750nm is less than 30% of the maximum intensity in the wavelength range of 380nm and above to 2500nm.

[0188] In the light-emitting device 10 of this embodiment, the output light 9 has a trough T in the wavelength range of 650 nm to 750 nm, and the visible light component and the near-infrared light component are separated with the trough T as the boundary. Therefore, when the light-emitting device 10 is used in combination with a near-infrared detector, the object to be inspected can be well inspected by visual inspection in addition to the detector.

[0189] [Electronic Devices]

[0190] Next, the electronic device according to this embodiment will be described. The electronic device according to this embodiment includes the light-emitting device 10 described above. Figure 7 The image below shows a simplified example of an electronic device related to this embodiment.

[0191] In the electronic device 20, the light-emitting device 10 includes at least a power supply circuit 11, a conductor 12, and a light-emitting part 13. The power supply circuit 11 supplies power to the light-emitting part 13 and supplies electrical energy to the light-emitting part 13 via the conductor 12.

[0192] The light-emitting unit 13 includes the first light-emitting element 5, the second light-emitting element 6, the first phosphor 7, and the second phosphor 8 described above. Furthermore, the light-emitting unit 13 converts electrical energy into light energy. That is, the light-emitting unit 13 converts at least a portion of the electrical energy supplied from the power supply circuit 11 into light energy as output light 9 and outputs it.

[0193] The electronic device 20 also includes a first detector 17 and a second detector 17A. The first detector 17 detects the transmitted light component 15 of the output light 9 emitted from the light-emitting device 10 and illuminating the irradiated object 14. Specifically, the first detector 17 detects near-infrared light in the transmitted light component 15 that has transmitted through the irradiated object 14. The second detector 17A detects the reflected light component 16 of the output light 9 emitted from the light-emitting device 10 and illuminating the irradiated object 14. Specifically, the second detector 17A detects near-infrared light in the reflected light component 16 reflected by the irradiated object 14.

[0194] In the electronic device 20 with such a structure, output light 9 containing near-infrared light components is irradiated onto the object 14. The transmitted light component 15 that passes through the object 14 and the reflected light component 16 that is reflected by the object 14 are detected by the first detector 17 and the second detector 17A, respectively. Therefore, the electronic device 20 can detect the characteristic information of the object 14 affected by the near-infrared light components.

[0195] Here, the light-emitting device of this embodiment is capable of emitting output light 9, which includes visible light and near-infrared light and is suitable for human eyes and detectors. Therefore, by combining this light-emitting device with a near-infrared detector, an electronic device suitable for industrial applications is created.

[0196] Furthermore, the light-emitting device of this embodiment can illuminate a large area of ​​structure by using high-energy output light 9. Therefore, even when the output light 9 is shone onto the object 14 from a distant distance, a signal with a good S / N ratio (signal-to-noise ratio) can be detected. Thus, it becomes an electronic device suitable for inspecting large objects 14, inspecting objects distributed over a large area together, detecting objects existing in a portion of a large inspection area, and detecting people or objects from a distance.

[0197] For reference, the dimensions of the light-emitting device in this embodiment are described below. For example, the area of ​​the main light extraction surface of the light-emitting section 13 can be set to 1 cm². 2 Above and less than 1m 2 The preferred setting is 10cm. 2Above and below 1000cm 2 Furthermore, the shortest distance from the light-emitting part 13 to the irradiated object 14 is, for example, 1 mm or more and less than 10 m. In cases where it is necessary to irradiate the irradiated object 14 with strong near-infrared radiation, such as in medical, cosmetic, or delicate foreign body inspection applications, the shortest distance from the light-emitting part 13 to the irradiated object 14 can be set to 1 mm or more and less than 30 cm, preferably 3 mm or more and less than 10 cm. Furthermore, in cases where it is necessary to inspect a large area of ​​the irradiated object 14, the shortest distance from the light-emitting part 13 to the irradiated object 14 can be set to 30 cm or more and less than 10 m, preferably 1 m or more and less than 5 m.

[0198] Furthermore, when it is necessary to irradiate a large area with strong near-infrared radiation, it is preferable to adopt a structure in which the light-emitting part 13 is movable, and more preferably, a structure in which it can move freely according to the shape of the irradiated object. For example, the light-emitting part 13 may be a structure that can move back and forth on a straight line or curve, a structure that can scan in the XY axis direction or the XYZ direction, or a structure that is mounted on a moving body (a flying body such as a car, bicycle, or drone).

[0199] The first detector 17 and the second detector 17A can be various photodetectors. Specifically, depending on the application of the electronic device, quantum photodetectors (photodiodes, phototransistors, photoelectric ICs, CCD image sensors, CMOS image sensors, etc.) that detect the charge generated when light is incident on the PN junction of a semiconductor can be used. In addition, thermal photodetectors (thermoelectric piles utilizing the thermoelectric effect, pyroelectric elements utilizing the pyroelectric effect, etc.) or light-sensitive infrared films can also be used as photodetectors.

[0200] The first detector 17 and the second detector 17A can be either individual elements utilizing photoelectric conversion elements or imaging elements integrating photoelectric conversion elements. The imaging element can be either a one-dimensional linear shape or a two-dimensional planar shape. A camera can also be used as the first detector 17 and the second detector 17A.

[0201] in addition, Figure 7 The electronic device 20 has both a first detector 17 and a second detector 17A, but the electronic device only needs to have at least one of the first detector 17 and the second detector 17A.

[0202] Furthermore, the electronic device in this embodiment is preferably an inspection device, detection device, monitoring device, or differentiation device for the irradiated object. The output light has a near-infrared light component that has the property of transmitting through almost all substances. Therefore, by employing a structure that irradiates the irradiated object with near-infrared light from the outside and detects its transmitted or reflected light, it is possible to inspect the internal state, presence or absence of foreign objects, etc., without damaging the irradiated object.

[0203] Furthermore, the near-infrared light component is invisible to the human eye, and its reflectivity depends on the material. Therefore, by illuminating an object with near-infrared light and detecting the structure of its reflected light, it is possible to detect the object without human intervention, even in darkness.

[0204] The electronic device of this embodiment can inspect the internal state and presence of foreign objects of the irradiated object without damaging it, thereby determining whether the irradiated object is qualified or not, and distinguishing between qualified and unqualified products. Therefore, the electronic device also has a mechanism to distinguish between irradiated objects in a normal state and irradiated objects in an abnormal state, enabling the differentiation of irradiated objects.

[0205] In the electronic device of this embodiment, the light-emitting device can be fixed rather than movable. If so, there is no need for a complex mechanism to mechanically move the light-emitting device, thus making it a less prone-to-malfunction electronic device. Furthermore, by fixing the light-emitting device indoors or outdoors, it is possible to observe the status of people and objects in a pre-defined location at a specific point, or to count the number of people and objects. Therefore, it becomes an electronic device that facilitates the collection of large amounts of data beneficial for problem discovery and commercial applications. Examples of fixed electronic devices equipped with light-emitting devices include shop lighting, indoor lighting, streetlights, and surgical lighting devices.

[0206] The electronic device of this embodiment can also have a movable light-emitting device to change the location of illumination. For example, the light-emitting device can be mounted on a mobile platform or mobile body (vehicle, aircraft, etc.) to make it movable. In this case, the light-emitting device can illuminate a desired location or a large area, thus becoming an electronic device that is beneficial for inspecting large objects or checking the condition of outdoor objects. In addition, drones can be cited as an example of an electronic device with a movable light-emitting device.

[0207] The electronic device of this embodiment can be structured to include a hyperspectral camera, which functions as a camera in addition to a light-emitting device. Therefore, this electronic device is capable of hyperspectral imaging. Electronic devices equipped with hyperspectral cameras can distinguish differences that cannot be discerned by the naked eye or by ordinary cameras as images, thus becoming useful inspection devices in a wide range of fields involving product inspection and screening.

[0208] Specifically, such as Figure 8As shown, the electronic device 20A includes a light-emitting device 10 and a hyperspectral camera 21. Furthermore, while irradiating the object 23 placed on the surface 22a of the conveyor 22 with output light 9 from the light-emitting device 10, the hyperspectral camera 21 captures an image of the object 23. By analyzing the obtained image of the object 23, the object 23 can be inspected and identified.

[0209] The electronic device of this embodiment is preferably equipped with a data processing system for machine learning, in addition to a light-emitting device. This allows for repeated learning of data input into the computer to identify hidden patterns. Furthermore, newly input data can be applied to these patterns. Therefore, this electronic device facilitates automation and high precision in inspection, detection, and monitoring, and further enables future predictions using big data.

[0210] The electronic device of this embodiment can also be used in medical, veterinary, biotechnology, agricultural, forestry and fisheries, animal husbandry (eating meat, meat products, dairy products, etc.), or industrial applications (foreign object inspection, content volume inspection, shape inspection, packaging condition inspection, etc.). Furthermore, the electronic device can also be used for the inspection of pharmaceuticals, animal experiments, food, beverages, agricultural, forestry and fisheries products, livestock products, and industrial products. In other words, the electronic device of this embodiment can be used on any human body, animal or plant, or object, and further, on any gas, liquid, or solid.

[0211] The electronic device in this embodiment is preferably 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, or an evaluation device.

[0212] For example, in the context of medical and biotechnology development, the electronic device of this embodiment can be used for: 1) blood, body fluids and their components; 2) excretions (urine, feces); 3) proteins, amino acids; 4) cells (including cancer cells); 5) genes, chromosomes, nucleic acids; 6) biological samples, bacteria, specimens, antibodies; 7) biological tissues, organs, blood vessels; 8) examination, detection, measurement, evaluation, analysis, interpretation, observation, monitoring, separation, diagnosis, treatment, purification, etc., of skin diseases and alopecia.

[0213] Furthermore, for purposes such as beauty and health management, the electronic device of this embodiment can be used for: 1) skin; 2) hair, body hair; 3) oral cavity, dental cavity, periodontal cavity; 4) ear, nose; 5) examination, detection, measurement, evaluation, analysis, interpretation, observation, monitoring, beautification, hygiene, development promotion, health enhancement, diagnosis, etc.

[0214] For example, in agricultural, forestry, fishery, animal husbandry, and industrial applications, the electronic equipment of this embodiment can be used for: 1) industrial products (including electronic components and electronic devices); 2) agricultural products (vegetables, fruits, etc.); 3) enzymes and bacteria; 4) marine products (fish, shellfish, crustaceans, mollusks); 5) pharmaceuticals and biological samples; 6) food and beverages; 7) the existence and state of humans, animals, and objects; 8) the state of gases (including water vapor); 9) liquids, fluids, water, moisture, and humidity; 10) the shape, color, internal structure, and physical state of objects; 11) space, location, and distance; 12) the pollution state of objects; 13) the state of molecules and particles; 14) the inspection, detection, measurement, evaluation, analysis, interpretation, observation, monitoring, identification, screening, and differentiation of industrial waste.

[0215] For example, in the purpose of care, the electronic device of this embodiment can be used for excretion confirmation, health status identification, management, monitoring, etc.

[0216] Thus, the electronic device of this embodiment can handle all uses such as inspection, detection, measurement, evaluation, analysis, interpretation, observation, monitoring, identification, discrimination, and differentiation.

[0217] In addition, this embodiment can also be regarded as any simple method invention of inspection method, detection method, monitoring method, differentiation method, analysis method, measurement method, and evaluation method using the light-emitting device 10.

[0218] Example

[0219] The light-emitting device of this embodiment will be described in more detail below through examples, but this embodiment is not limited to these examples.

[0220] First, a second wavelength converter 8A is fabricated to emit second wavelength-converted light 4A, which serves as the source of the fourth light component 4. The second wavelength converter 8A is configured to contain light emitted by Cr... 3+ A resin fluorescent film with activated composite metal oxide as the main phosphor. Additionally, Cr... 3+ Activated composite metal oxides using (Gd 0.95 La 0.05 )3(Ga 0.97 Cr 0.03 The composition of (Gd,La)3Ga2(GaO4)3 and the crystal structure of (Gd,La)3Ga2(GaO4)3:Cr are represented by the formula (Gd,La)3Ga2(GaO4)3 and have a garnet-type crystal structure. 3+ Phosphor. Later, (Gd,La)3Ga2(GaO4)3:Cr 3+ The phosphor is also known as a GLGG phosphor.

[0221] GLGG phosphors use the following compound powders as the main raw materials and are modulated through conventional solid-phase reactions.

[0222] Gadolinium oxide (Gd₂O₃): Purity 3N, manufactured by Yttrium Corporation of Japan.

[0223] Lanthanum hydroxide (La(OH)3): Purity 3N, manufactured by Shin-Etsu Chemical Co., Ltd.

[0224] Gallium oxide (Ga2O3): Purity 4N, manufactured by Asia Physical Properties Co., Ltd.

[0225] Chromium oxide (Cr2O3): Purity 3N, manufactured by High Purity Chemical Research Institute Co., Ltd.

[0226] Specifically, first, the above raw materials are weighed to produce a compound (Gd) with a stoichiometric composition through a chemical reaction. 0.95 La 0.05 )3(Ga 0.97 Cr 0.03 )2(GaO4)3. For reference, this weighing value is shown in Table 1.

[0227] [Table 1]

[0228]

[0229] Next, 20g of the weighed raw material was added to a 250ml alumina ball mill, along with alumina balls and 60ml of ethanol. The alumina balls were φ3mm in diameter, totaling 200g. The ball mill was then used to mix the materials for 30 minutes at 150rpm using a planetary ball mill (FRITSCH, model P-5).

[0230] Next, the alumina balls were removed using a sieve, resulting in a slurry-like mixture of the raw material and ethanol. Then, the slurry-like mixture was completely dried at 125°C using a dryer. Finally, the dried mixture was gently mixed using a mortar and pestle to create a phosphor raw material.

[0231] Next, the phosphor raw material was placed into an alumina firing container (material SSA-H, B3 size, with lid) and fired in an atmospheric furnace at 1500°C for two hours. The heating and cooling rate during firing was set to 300°C / h.

[0232] The resulting calcined material was manually pulverized using an alumina mortar and pestle, and then passed through a nylon mesh (95μm mesh) to remove coarse particles. This yielded a product composed of (Gd... 0.95 La 0.05 )3(Ga 0.97 Cr 0.03GLGG phosphor in powder form, represented by the composition formula )2(GaO4)3.

[0233] Although data are omitted, the crystal structure of the obtained GLGG phosphor was evaluated using an X-ray diffraction apparatus (a desktop X-ray diffraction apparatus, MiniFlex, manufactured by Rigaku Corporation), and it was found to be a roughly monocrystalline garnet compound. Furthermore, the particle shape and size were evaluated using electron microscopy; the particle morphology was monodisperse, the particle shape was consistent with garnet crystals, and the main particle size was approximately 15 μm. The electron microscope used was a Hitachi High-Tech Miniscope TM4000 desktop microscope (registered trademark), manufactured by Hitachi High-Tech Corporation.

[0234] Furthermore, the fluorescence properties of the GLGG phosphor were evaluated using an absolute PL quantum yield measurement device (C9920-02, manufactured by Hamamatsu Photonics Co., Ltd.) under blue light illumination at a wavelength of 450 nm. The results showed a fluorescence peak wavelength of 747 nm, an internal quantum efficiency (IQE) of 92%, and a blue light absorptivity (Abs.) of 57%. Additionally, evaluation under red light illumination at a wavelength of 628 nm yielded a fluorescence peak wavelength of 746 nm, an internal quantum efficiency (IQE) of 93%, and a red light absorptivity (Abs.) of 45%.

[0235] Next, a resin fluorescent film was fabricated using the GLGG phosphor. Specifically, the resin fluorescent film was obtained by curing a phosphor paste obtained by degassing a mixture of silicone resin and GLGG phosphor. Furthermore, the resin used as the sealant for the phosphor powder was a two-component added-curing silicone resin (product name KER-2500A / B, manufactured by Shin-Etsu Chemical Industry Co., Ltd.).

[0236] The fluorescent paste described above is prepared as follows: First, weigh out equal amounts of silicone resin (equal amounts of agent A and agent B) and GLGG phosphor to achieve a phosphor powder filling rate of 30% by volume in the resin. Next, mix the silicone resin and phosphor powder using a mortar and pestle. Then, obtain the fluorescent paste by vacuuming (degassing) the resulting mixture.

[0237] Furthermore, the aforementioned resin fluorescent film is manufactured as follows: First, strips with a thickness of 100 μm are bonded to a glass substrate in pairs with equal spacing of 15 mm. Next, phosphor paste is dropped between the paired strips, and after smoothing the surface using a brush, the strips are peeled off. Then, the phosphor paste is hardened by heating it at 150°C in the atmosphere for two hours to obtain a phosphor sheet. Next, the obtained phosphor sheet is peeled off from the glass using tweezers and cut to an appropriate size (10 mm in length and width) with scissors. Thus, a resin fluorescent film (a second wavelength converter 8A with light transmittance) is obtained.

[0238] In addition, three fluorescent films with different thicknesses (actual thicknesses: 100μm, 200μm, and 270μm) were manufactured as resin fluorescent films. Their thicknesses were controlled by making the strips attached to the glass substrate into two or three layers.

[0239] The fluorescence properties of the obtained resin fluorescent film were evaluated using the aforementioned absolute PL quantum yield measurement device. Table 2 shows the evaluation results of the resin fluorescent film under blue light excitation at a wavelength of 450 nm. In Table 2, IQE is the internal quantum efficiency, and Abs. is the light absorptivity. Furthermore, EQE is the external quantum efficiency, which can be calculated by multiplying IQE by Abs. λp is the fluorescence peak wavelength of the fluorescence spectrum.

[0240] [Table 2]

[0241]

[0242] As shown in Table 2, samples No. 1 to 3 are the results of evaluating each resin fluorescent film with a physical thickness of 100 μm, 200 μm, and 270 μm individually. In addition, samples No. 4 to 11 are the results of evaluating the structure of resin fluorescent films with the thicknesses and number of sheets shown in Table 2 stacked together.

[0243] As shown in Table 2, the internal quantum efficiency of the resin fluorescent film exceeds 80% regardless of its thickness, and is often at a high efficiency level of around 90%, exceeding 85%. Furthermore, the light absorption rate tends to increase with increasing thickness, saturating above a total thickness of 800 μm. Additionally, the light absorption rate is 41% with a total thickness of 100 μm and 64% with a total thickness of 1590 μm. The peak fluorescence wavelength emitted by the resin fluorescent film does not change significantly with the total thickness, remaining a constant value between 730 nm and 736 nm.

[0244] In addition, Table 3 shows the evaluation results of the resin fluorescent film excited by red light at a wavelength of 628 nm.

[0245] [Table 3]

[0246]

[0247] As shown in Table 3, similar to the blue light excitation case shown in Table 2, the internal quantum efficiency of the resin fluorescent film exceeds 80% regardless of its thickness, often reaching a high efficiency level of around 90% (over 85%). Furthermore, the light absorption rate tends to increase with increasing thickness, saturating above a total thickness of 800 μm. Additionally, the light absorption rate is 25% with a total thickness of 100 μm and 54% with a total thickness of 1590 μm. The fluorescence peak wavelength emitted by the resin fluorescent film does not change significantly with the total thickness, remaining a constant value between 730 nm and 738 nm.

[0248] Next, a light-emitting device was fabricated using a resin fluorescent film whose fluorescence properties are shown in Tables 2 and 3. Specifically, firstly, a blue LED, serving as the first light-emitting element 5, which emits the first primary light 1A, and Y3Al2(AlO4)3:Ce, containing a fluorescence peak wavelength of 540nm, were prepared. 3+ A commercially available white LED is constructed by combining a phosphor film with a phosphor as the first wavelength converter 7A. This commercially available white LED is manufactured by EK JAPAN Co., Ltd., trade name: Coated Ultra-High Brightness LED (Blue), model: LK-5WH-C50. Furthermore, the peak wavelength of the first primary light 1A (blue light) is 460nm. Additionally, Y3Al2(AlO4)3:Ce 3+ The phosphor is also known as a YAG phosphor.

[0249] Furthermore, a commercially available red LED is prepared as the second light-emitting element 6 to emit a second primary light 2A as red light (peak wavelength: 630nm). The commercially available red LED is manufactured by EK JAPAN Co., Ltd., trade name: Coated Ultra-High Brightness LED (Red), model: LK-5RD-C50.

[0250] For reference, Figure 9 The diagram shows the spectral distribution of commercially available white LEDs and commercially available red LEDs. The light emitted by the commercially available white LED is located at (x, y) = (0.267, 0.272) on the CIE chromaticity diagram, with a correlated color temperature of 13514 K, a duv value of 0.2, an average color rendering index (Ra) of 82, and a specific color rendering index (R9) of 21. Furthermore, the fluorescence intensity at a wavelength of 540 nm is 25% of the fluorescence intensity at a wavelength of 460 nm. On the other hand, the light emitted by the commercially available red LED is located at (x, y) = (0.679, 0.314) on the CIE chromaticity diagram.

[0251] Furthermore, the spectral distribution of the white LED varies depending on the blue LED used, the hue (fluorescence peak wavelength) of the fluorescence emitted by the YAG phosphor, and the light absorption rate of the first wavelength converter 7A containing the YAG phosphor. Additionally, the light absorption rate of the first wavelength converter 7A varies depending on the volume ratio of the YAG phosphor in the first wavelength converter 7A and the thickness of the first wavelength converter 7A. The light absorption rate of the first wavelength converter 7A also varies depending on the Ce of the YAG phosphor used. 3+ Activation level, composition of YAG phosphor (Gd substitution ratio of Y, Lu substitution ratio of Y, Ga substitution ratio of Al, etc.), particle size of YAG phosphor (central diameter D) 50 The color of the output light can vary. Furthermore, besides the white LED used in this embodiment, commercially available white LEDs emit a wide variety of shades of white light. Therefore, by using a suitable white LED, it is possible to control the color of the output light, etc.

[0252] For reference, Figure 10 The text shows an example of the spectral distribution of a white LED that can be fabricated using the blue LED (fluorescence peak: 460 nm) and YAG phosphor (fluorescence peak: 540 nm) that constitute the aforementioned white LED. Furthermore, Figure 10 These are simulation results of increasing the fluorescence intensity of the YAG phosphor in the spectral distribution of the aforementioned white LED by 20%, 40%, 60%, 80%, and 100% (doubling). Furthermore, as described above, a white LED emitting white light with such a spectral distribution can be obtained by increasing the volume ratio of the YAG phosphor in the first wavelength converter 7A or increasing the thickness of the first wavelength converter 7A. Table 4 shows the characteristics of the illumination light when the fluorescence intensity of the YAG phosphor is increased.

[0253] [Table 4]

[0254]

[0255]

[0256] Next, using the aforementioned white and red LEDs, construct the light-emitting device as follows. First, as... Figure 11 As shown, a red LED (second light-emitting element 6) is disposed near a white LED, which is formed by arranging a YAG phosphor (first wavelength converter 7A) to cover the light output surface of a blue LED (first light-emitting element 5). Furthermore, a resin phosphor film (second wavelength converter 8A) containing a GLGG phosphor is disposed directly above the light output surface of the red LED.

[0257] Furthermore, regarding the resin fluorescent film, considering the ratio of the output wavelength-converted light obtained from the resin fluorescent film to the intensity of the red light transmitted through the resin fluorescent film, a No. 11 fluorescent film consisting of six layers of resin fluorescent film with a thickness of 265 μm was used. Additionally, the light absorption rate of the red light from this stacked resin fluorescent film is 54%, as shown in Table 3. Therefore, if a structure with a light absorption rate of 50% or more and less than 60% is used as the second wavelength converter 8A, it is possible to design a light-emitting device that emits output light with the same spectral distribution as in this example.

[0258] Next, a configuration is made to focus the wavelength-converted light from the white LED, the red LED (transmitted through the resin phosphor film), and the near-infrared light from the resin phosphor film. Furthermore, in this example, a frosted glass-like light diffuser D is used to achieve uniformity in the output light quality of the output light 9.

[0259] With this structure, a first mixed light component is obtained by mixing the blue light emitted by the blue LED (first primary light 1A) with the yellow-green light component emitted by the YAG phosphor (first wavelength-converted light 3A). Furthermore, a second mixed light component is obtained by mixing the red light emitted by the red LED (second primary light 2A) with the near-infrared light component emitted by the GLGG phosphor (second wavelength-converted light 4A). The light-emitting device in this example outputs the mixed light of the first and second mixed light components as the output light.

[0260] Next, using the obtained light-emitting device, output light with different proportions of the first mixed light component and the second mixed light component was obtained. That is, by adjusting the shortest distance from the light-illuminating surface of the light-emitting device to the light-output surface of the white LED and the shortest distance from the light-illuminating surface to the light-output surface of the resin phosphor film, output light with different proportions of the first mixed light component and the second mixed light component was obtained.

[0261] Specifically, in Embodiment 1, the distance from the light-irradiating surface to the light-output surface of the resin phosphor film is set to a constant, while the distance from the light-irradiating surface to the light-output surface of the white LED is relatively short. In Embodiment 2, the distance from the light-irradiating surface to the light-output surface of the resin phosphor film is the same as in Embodiment 1, but the distance from the light-irradiating surface to the light-output surface of the white LED is longer than in Embodiment 1. In Embodiment 3, the distance from the light-irradiating surface to the light-output surface of the resin phosphor film is the same as in Embodiments 1 and 2, but the distance from the light-irradiating surface to the light-output surface of the white LED is longer than in Embodiment 2. Furthermore, the longer the distance from the light-irradiating surface to the light-output surface of the white LED, the lower the intensity of the first primary light 1A and the first wavelength-converted light 3A included in the output light of the light-emitting device.

[0262] exist Figure 12The diagram shows the beam distribution of the output light in Examples 1-3. Figure 12 As shown, the output light 9 exhibits a trough in its spectral distribution within the wavelength range of 650 nm to 750 nm. The visible light and near-infrared components are separated at this trough. Furthermore, it is known that the minimum intensity in the wavelength range above 650 nm and below 750 nm, specifically near wavelength 675 nm, is less than 30% of the maximum intensity in the wavelength range above 380 nm and below 2500 nm, specifically near wavelengths 460 nm or 755 nm.

[0263] Table 5 summarizes Figure 12 The spectroscopic distribution shows the correlated color temperature, duv, average color rendering index Ra, and special color rendering index R9 (a value used as a measure of the color rendering of vivid red).

[0264] [Table 5]

[0265] Example 1 12970 -18.7 82 11 Example 2 8137 -28.7 73 -40 Example 3 3869 -37.1 65 -33

[0266] As shown in Table 5, the output light of Examples 1-3 is a color temperature suitable for general lighting, with a correlated color temperature of 3800 or higher and less than 13000, and a div value within ±40. Furthermore, the average color rendering index (CRI) of the output light in Examples 1-3 is 60 or higher and less than 85, and the specific CRI R9 is -40 or higher and less than 15. Additionally, although data is omitted, by changing the number of layers of the resin fluorescent film in the light-emitting device, the correlated color temperature of the output light can be varied within the range of 1700K or higher and less than 13000K, particularly within the range of 2800K or higher and less than 13000K.

[0267] Furthermore, in Examples 1-3, the reason for obtaining the result that duv oscillates to the negative side and Ra is included in the range of less than 85 is based on... Figure 9 As can be seen from the spectral distribution, this is because the proportion of green light component is low in the white LED used in the embodiment. Therefore, for example, by using the emission of light with a distribution such as... Figure 10 White LEDs with a high proportion of green light component and a spectral distribution, and a duv value exceeding 4, preferably exceeding 10, can improve these conditions.

[0268] Here, the spectral distribution of the output light obtained by adjusting the green light component can be utilized... Figure 10 The spectral distribution shown and Figure 12 The spectral distribution shown is simulated with relatively high accuracy. Furthermore, the correlated color temperature, duv, and Ra of the output light can be calculated based on this spectral distribution. Therefore, the effect of adjusting the green light component in the output light was studied through simulation.

[0269] Figure 13 Indicates based on Figure 12 The data from Example 2 simulated the spectroscopic distribution obtained by adjusting the proportion of the green light component. Example 4 increased the fluorescence intensity of YAG by 20% compared to the data from Example 2. Example 5 increased the fluorescence intensity of YAG by 40% compared to the data from Example 2. Example 6 increased the fluorescence intensity of YAG by 60% compared to the data from Example 2. Example 7 increased the fluorescence intensity of YAG by 80% compared to the data from Example 2. Example 8 increased the fluorescence intensity of YAG by 100% compared to the data from Example 2.

[0270] For reference, Table 6 shows Figure 13 The correlated color temperature, duv, average color rendering index Ra, and special color rendering index R9 in the spectroscopic distributions of Examples 4-8 are shown.

[0271] [Table 6]

[0272] Example 4 6821 -20.2 82 11 Example 5 6100 -13.3 89 51 Example 6 5713 -7.2 94 80 Example 7 5465 -2 95 95 Example 8 5308 2.4 93 78

[0273] As shown in Table 6, by adjusting the proportion of the green light component, an output light with a correlated color temperature of 5000 or higher and less than 7000, suitable for general lighting, was obtained. Furthermore, an output light with a hue close to natural light, with a duv value within the range of ±21, preferably ±10, and more preferably ±5, was obtained. Moreover, an output light with high color rendering index (CRI) of 82 or higher and less than 96 was also obtained. In addition, output lights with an average CRI exceeding 85 and an average CRI exceeding 90 were also obtained. Furthermore, an output light with a specific CRI R9 of 10 or higher was obtained. In particular, an output light with a specific CRI R9 of 50 or higher and less than 96 is suitable for emphasizing the red hue when illuminating objects with a reddish tint.

[0274] Thus, in Examples 4-8, the white LED used in Example 2 is replaced with a white LED that emits white light with a correlated color temperature of less than 10000K and a duv value of more than 4. As a result, it is known that a light-emitting device can be provided that simultaneously emits white light with a Ra value of 80 or higher, exhibiting high color rendering index (CRI), and a relatively high output near-infrared light component. Furthermore, it is known that a light-emitting device can be provided that simultaneously emits white light with a high red CRI of more than 10, white light with a duv value of ±21 that is close to the quality of natural light, and a near-infrared light component.

[0275] Furthermore, as described above, in this example of the light-emitting device, by adjusting the shortest distance from the light-irradiating surface to the light-output surface of the white LED and the shortest distance from the light-irradiating surface to the light-output surface of the resin phosphor film, output light with different proportions of the first mixed light component and the second mixed light component can be obtained. Therefore, this light-emitting device can also be regarded as a light-emitting device equipped with a tone adjustment mechanism for adjusting the output proportions of multiple primary light components (first light component and second light component) and / or a tone adjustment mechanism for adjusting the output proportions of multiple wavelength-converted light components (third light component and fourth light component).

[0276] In this example, a resin fluorescent film containing a GLGG phosphor was used as the second wavelength converter 8A. However, for higher output, an inorganic encapsulated fluorescent film or fluorescent ceramic can be used instead of a resin fluorescent film. For example, fluorescent ceramic can be modulated using manufacturing techniques for transparent YAG fluorescent ceramic or transparent alumina light-emitting diodes.

[0277] Furthermore, although data is omitted, it has been confirmed that irradiating a fluorescent ceramicized GLGG phosphor (thickness: 530 μm) with, for example, 24.7 W of blue light releases 11.1 W of wavelength-converted light with a fluorescence peak of 755 nm. In this case, the blue light is obtained using a high-output blue LED module (fluorescence peak wavelength: 459 nm, drive DC 30-40 V, 3000 mA) with 100 0.25 W blue LED chips (0.8 mm x 0.8 mm) mounted on a 20 cm x 20 cm substrate. Furthermore, it has been confirmed that even when irradiating the same fluorescent ceramic with 14.3 W of red light emitted by a high-output red LED module of equivalent specifications (fluorescence peak wavelength: 664 nm, drive DC 30-40 V, 3000 mA), approximately 80% of its wavelength-converted light is released.

[0278] Therefore, according to this embodiment, a light-emitting device can be obtained that not only emits near-infrared light components with a light energy exceeding 3W, but also emits high-output near-infrared light components exceeding 10W. Such a high-output light-emitting device can irradiate objects with strong near-infrared radiation, so even at a large distance from the irradiated object, it can irradiate the object with relatively strong near-infrared radiation.

[0279] Furthermore, fluorescent ceramics composed of GLGG phosphors can be obtained, for example, as follows: First, 19g of phosphor raw material composed of the materials shown in Table 1 is filled into a metal mold (φ50mm), and stamped under a pressure of approximately 190MPa to form a shaped body of the phosphor raw material. The shaped body of the phosphor raw material is disc-shaped, with a diameter φ of 50mm and a height of 3.1mm. Next, the shaped body is placed on an alumina plate (60mm long, 100mm wide, and 1.5mm thick) placed on a large alumina firing plate (material SSA-S), and fired in a tubular atmosphere furnace at 1500–1600°C in a nitrogen atmosphere for two hours. The heating and cooling rate during firing is set to 300°C / h. This yields a disc-shaped sintered body. By mechanically grinding the top and bottom surfaces of the sintered body with a grinding machine to achieve a specified thickness, fluorescent ceramics composed of GLGG phosphors are obtained.

[0280] The above describes this embodiment, but this embodiment is not limited to these and various modifications can be made within the scope of the spirit of this embodiment.

[0281] This document quotes the full contents of Japanese Special Application No. 2020-084496 (application date: May 13, 2020) and Japanese Special Application No. 2021-014818 (application date: February 2, 2021).

[0282] Industrial availability

[0283] According to this disclosure, a light-emitting device that emits output light that allows for good visual inspection of the object being inspected, in addition to the detector, when used in combination with a near-infrared detector, and an electronic device using the light-emitting device are provided.

[0284] Label Explanation

[0285] 1. First light component

[0286] 1A First Light

[0287] 2 Second light component

[0288] 2A Second Light

[0289] 3 Third light component

[0290] 3A First Wavelength Conversion Light

[0291] 4. Fourth light component

[0292] 4A Second Wavelength Conversion Light

[0293] 5 First light-emitting element

[0294] 6 Second light-emitting element

[0295] 7 First fluorescent agent

[0296] 7A First Wavelength Converter

[0297] 8 Second fluorescent

[0298] 8A Second Wavelength Converter

[0299] 9 Output light

[0300] 10. Light-emitting device

[0301] 20, 20A Electronic Equipment

[0302] T trough

Claims

1. A light-emitting device that emits output light, comprising: The first light-emitting element emits the first light component; The second light-emitting element, unlike the first light-emitting element, emits a second light component; The first phosphor emits the third component of light; as well as The second phosphor, unlike the first phosphor, emits a fourth light component. in, The output light described above includes the first light component, the second light component, the third light component, and the fourth light component, each with a different hue. The aforementioned first light component is the visible light component that originates from the first primary light emitted by the aforementioned first light-emitting element and has a maximum intensity in the wavelength range of 435 nm or higher and less than 480 nm. The aforementioned second light component is the visible light component that originates from the second primary light emitted by the aforementioned second light-emitting element and has a maximum intensity in the wavelength range of 600 nm to less than 680 nm. The aforementioned third light component is the visible light component that originates from the first wavelength-converted light emitted by the first phosphor and has a maximum intensity in the wavelength range of 500 nm to 600 nm. The aforementioned fourth light component is the near-infrared light component that originates from the second wavelength-converted light emitted by the second phosphor and has a maximum intensity in the wavelength range of 700 nm to 2500 nm. The output light has a trough in the wavelength range of 650nm and below 750nm, and the minimum intensity in the wavelength range of 650nm and below 750nm is less than 30% of the maximum intensity in the wavelength range of 380nm and below 2500nm.

2. The light-emitting device as claimed in claim 1, wherein, The fourth light component is the light obtained by wavelength conversion of the second light component by the second phosphor.

3. The light-emitting device as described in claim 1 or 2, wherein, The aforementioned third light component is the light obtained by wavelength conversion of the aforementioned first light component by the aforementioned first phosphor.

4. The light-emitting device as described in claim 1 or 2, wherein, The output light is white.

5. The light-emitting device as claimed in claim 4, wherein, The average color rendering index Ra of the above output light exceeds 80.

6. The light-emitting device as claimed in claim 1 or 2, wherein, The mixed light component of the first light component and the third light component, and the mixed light component of the second light component and the fourth light component are output from different output surfaces.

7. The light-emitting device as claimed in claim 1 or 2, wherein, The mixed light component of the first light component and the third light component, and the mixed light component of the second light component and the fourth light component are output from the same output surface.

8. The light-emitting device as claimed in claim 1 or 2, wherein, The light energy of the light component with a wavelength above 700nm in the above output light exceeds 3W.

9. The light-emitting device as claimed in claim 1 or 2, wherein, The photons that are to be converted into the fourth light component by the second phosphor are supplied by multiple solid-state light-emitting elements.

10. The light-emitting device as claimed in claim 1 or 2, wherein, The wavelength converter containing the second phosphor allows the fourth light component to be transmitted.

11. The light-emitting device as claimed in claim 1 or 2, wherein, The aforementioned second phosphor contains Cr 3+ As a fluorescent ion.

12. An electronic device, wherein, The light-emitting device is provided with any one of claims 1 to 11.

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