A far-red light LED device and its applications

Abstract

The present invention belongs to the field of LED device preparation, and discloses a far-red light LED device and its application. The LED device is prepared by mixing a far-red light phosphor, transparent silica gel, and optionally a red light phosphor, and encapsulating through an encapsulation process; the chemical formula of the far-red light phosphor is: RE3(Ga 1‑x Cr x )5O 12 , where RE is at least one of Gd, Y, and Lu, 0.001

Description

Technical Field

[0001] The invention belongs to the field of LED device preparation, and more specifically, relates to a far-infrared LED device and its application. Background Art

[0002] Juvenile myopia is a global social problem and a major public health issue that affects the quality of the nation, especially the eye health of young people. The widespread prevalence of myopia around the world urgently requires the development of new prevention and control technologies and medical equipment to respond.

[0003] Myopia is caused by multiple factors, and the pathogenesis of myopia is still unknown. The latest view is that myopia is related to scleral hypoxia at the fundus, while the mainstream view is that the elongation of the eye axis in axial myopia is regulated by the neurotransmitter dopamine.

[0004] At present, the latest technologies used to prevent and control myopia mainly include titrating low-concentration atropine, wearing progressive multifocal lens frame glasses, wearing corneal reshaping lenses (OK lenses for short), and using 650nm laser irradiation of the light-feeding instrument. Each technology has its effectiveness, but also has its own advantages. The eye is a light detector that the human body uses to distinguish the intensity and chromaticity of visible light. For this reason, some people believe that photonic means and photonic technologies will ultimately be needed to solve a social problem such as juvenile myopia that affects a large population around the world. Outdoor exercise is recognized by all ophthalmologists as the most effective and safest way to prevent and control myopia. However, whether it is sunlight, air, water, or some mechanism that plays a role in outdoor exercise, there is no consensus on the mechanism of outdoor exercise in preventing and controlling myopia.

[0005] Therefore, it is urgent to propose an LED light-emitting device for the prevention, control and treatment of myopia in adolescents. Summary of the invention

[0006] The purpose of the present invention is to provide a far-red LED device and its application in view of the deficiencies of the prior art. The far-red LED device of the present invention is packaged by using far-red phosphor and a blue light chip with an emission wavelength of 440-480nm, which meets the demand for a new light source for the prevention and control of myopia in adolescents and non-invasive photobiological treatment.

[0007] To achieve the above object, the inventors collected spectra around the world for several consecutive years, covering land, under the shade of trees, deserts, grasslands, and the water surfaces of rivers, lakes, and seas. By comparing the spectra outdoors and indoors, we inferred that what can effectively prevent and control myopia during outdoor activities is not air, nor water vapor, but sunlight. And what sunlight acts on is not ultraviolet light or long-wave infrared light in the solar spectrum, but mainly red light-near infrared light with a wavelength of 600-1000 nm (for simplicity, in the present invention, photons in the range of 600-1000 nm are collectively referred to as far red light, that is, the far red light described in the present invention refers to light in the range of 600-1000 nm), especially far red light with a wavelength of 650-950 nm corresponding to the first therapeutic window of organisms. Based on this, the inventors also took two solar spectra collected under sunlight and under the shade of trees at 12:15 on August 5, 2021 in Hefei, China (latitude 31°52′, longitude 117°17′) as examples, such as Figure 1 and 2 . By comparing these two spectra, we can find that their significant difference lies in the 600-1000 nm band. By comparing the spectra collected at different times and places around the world, we believe that the band of 650-950 nm plays an effective role in preventing and controlling myopia in teenagers.

[0008] Therefore, in the first aspect of the present invention, there is provided a far red light LED device, which is prepared by mixing a far red light phosphor, transparent silica gel, and optionally a red light phosphor, and encapsulating through an encapsulation process;

[0009] The chemical formula of the far red light phosphor is: RE3(Ga 1-x Cr x )5O 12 , where RE is at least one of Gd, Y, and Lu, and 0.001 < x < 0.12.

[0010] According to the present invention, preferably, in the chemical formula RE3(Ga 1-x Cr x )5O 12 of the far red light phosphor, the value of x is: 0.03 < x < 0.06.

[0011] According to the present invention, preferably, the preparation method of the far red light phosphor includes:

[0012] The first step: Grind and mix evenly the raw materials containing Cr 3+ , the raw materials containing element Ga, the raw materials containing element RE, and the flux, and conduct the first calcination to obtain the product of the first step;

[0013] Step 2: Grind the product obtained in the first step, then conduct a second calcination, followed by crushing, grinding, washing with water, filtering, and drying to obtain the far-red phosphor.

[0014] According to the present invention, preferably, the raw material containing element RE is at least one of an oxide, nitrate, oxalate, and carbonate containing element RE.

[0015] According to the present invention, preferably, the raw material containing element Cr 3+ is at least one of an oxide, nitrate, oxalate, and carbonate containing element Cr 3+ .

[0016] According to the present invention, preferably, the raw material containing element Ga is at least one of an oxide, nitrate, oxalate, and carbonate containing element Ga.

[0017] According to the present invention, preferably, the operating conditions of the first calcination include: conducting in air, heating to 100 - 300°C at a rate of 3 - 10°C / min, holding for 0.3 - 1 hour, then heating to 400 - 600°C at a rate of 3 - 10°C / min, holding for 1 - 3 hours, powering off, and cooling to 25 - 30°C with the furnace.

[0018] According to the present invention, preferably, the operating conditions of the second calcination include: conducting in air, heating to 850 - 950°C at a rate of 3 - 10°C / min, holding for 0.5 - 2 hours, then heating to 1300 - 1450°C at a rate of 3 - 8°C / min, holding for 4 - 10 hours, then cooling to 300 - 800°C at a rate of 3 - 10°C / min, powering off, and cooling to 25 - 30°C with the furnace.

[0019] According to the present invention, preferably, the addition amount of the flux is 0.05 - 2.0 wt% of the total mass of the raw materials used for preparing the far-red phosphor.

[0020] According to the present invention, preferably, the flux is at least one of aluminum fluoride, barium fluoride, ammonium chloride, and boric acid. Preferably, the flux is boric acid.

[0021] According to the present invention, preferably, the emission wavelength range of the far-red phosphor is 600 - 1000 nm, and the peak emission wavelength is 650 - 900 nm.

[0022] According to the present invention, preferably, the dosage ratio of the far-red phosphor, the red phosphor, and the transparent silica gel is 1:(0 - 0.05):(0.2 - 0.8).

[0023] According to the present invention, preferably, the chemical formula of the red phosphor is (Ca,Sr)AlSiN3:Eu2+ or M2Si5N8:Eu 2+ where M is at least one of Sr, Ca, Ba, and Mg.

[0024] According to the present invention, preferably, the encapsulation process includes: defoaming and degassing a mixture of a far-red phosphor, transparent silica gel, and optionally a red phosphor, and then titrating the mixture onto a blue LED chip, followed by baking and curing to obtain the far-red LED device.

[0025] According to the present invention, preferably, the peak emission wavelength of the blue LED chip is 440 - 480 nm.

[0026] According to the present invention, preferably, the emission wavelength range of the far-red LED device is 600 - 1000 nm, and the peak emission wavelength is 650 - 900 nm.

[0027] The second aspect of the present invention provides an application of the described far-red LED device as a light source for preventing and treating juvenile myopia.

[0028] The beneficial effects of the technical solution of the present invention are as follows:

[0029] (1) The present invention uses a phosphor to encapsulate an LED device with a blue LED chip having an emission wavelength of 440 - 480 nm, and uses the LED device as the core light-emitting element to make a light source. The laser light source emits coherent light. In contrast to the laser, the present invention provides non-coherent light with high photobiological safety. The absorption spectrum generated by human cells is often a broadband spectrum. Compared with the laser and the light source made of multi-chip LEDs, the broadband spectrum emission provided by the present invention using a phosphor as a light conversion material can better meet the light absorption requirements of biological tissues.

[0030] (2) The far-red phosphor RE3(Ga 1-x Cr x )5O 12 belongs to the typical A3B2C3O 12 garnet structure, where the A-site is occupied by rare earth elements Gd, Y, or Lu, the B- and C-sites are doped with Ga elements, and Cr partially replaces Ga as the luminescence center. According to the lattice thermal vibration model, the more complex the components of the far-red phosphor, the more phonon vibration modes there are, and theoretically, its luminescence efficiency is lower. Cr 3+ as the luminescence center, a key technical problem faced in the synthesis by calcination in air is that Cr 3+ is transformed into Cr 4+ quenching luminescence. The present invention preferably uses boric acid as a flux, and boric acid as an electron center can prevent the formation of Cr 4+ .

[0031] (3) The cells that secrete the neurotransmitter dopamine in the human eye are mainly retinal pigment epithelial cells. According to the dopamine theory of myopia occurrence mechanism, to achieve dopamine secretion, first, the carrier that secretes dopamine - the retina - needs to be protected. One of the mechanisms of photobiomodulation therapy for acute diseases is that light activates cytochrome c oxidase to produce adenosine triphosphate (ATP) to provide energy for cells and reduce oxidative stress damage. The light emitted by the far - red light LED device of the present invention can effectively cover the absorption spectrum of cytochrome c oxidase; the present invention also confirms through retinal slices of mice raised in different light environments that the light emitted by the far - red light LED device of the present invention can effectively reduce the retinal damage effect caused by visible light and play a role in protecting the retina.

[0032] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0033] By describing the exemplary embodiments of the present invention in more detail in conjunction with the accompanying drawings, the above - mentioned and other objects, features, and advantages of the present invention will become more obvious. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0034] Figure 1 Shows the solar spectrum collected by the present invention under sunlight.

[0035] Figure 2 Shows the solar spectrum collected by the present invention under the shade of a tree.

[0036] Figure 3 Shows the emission spectra of a kind of far - red light LED device provided in Embodiment 1 of the present invention under different drive currents.

[0037] Figure 4 Shows the radiant optical power and photoelectric conversion efficiency of a kind of far - red light LED device provided in Embodiment 1 of the present invention under different drive currents.

[0038] Figure 5 Shows a comparison diagram of the emission spectrum of a kind of far - red light LED device provided in Embodiment 1 of the present invention and the absorption spectrum of cytochrome c oxidase.

[0039] Figure 6 Shows a schematic diagram of the emission spectra of the far - red light phosphors provided in Embodiments 2 - 3 and Comparative Examples 1 - 3 of the present invention under 471 nm blue light excitation.

[0040] Figure 7 Shows a schematic diagram of the excitation spectra of the far - red light phosphors provided in Embodiments 2 - 3 and Comparative Examples 1 - 3 of the present invention measured by monitoring the 742 nm emission.

[0041] Figure 8Shows the comparison diagram of the far-red phosphor provided by Embodiments 1-3 of the present invention with Figure 1 the solar spectrum.

[0042] Figure 9 Shows the comparison diagram of the far-red phosphor provided by Embodiments 1-3 of the present invention with Figure 2 the solar spectrum collected under the shade of a tree.

[0043] Figure 10 Shows the relationship between the integrated luminous intensity of the far-red phosphor provided by Embodiments 1-3 of the present invention and the temperature.

[0044] Figure 11 Shows a schematic diagram of the emission spectrum of the far-red phosphor provided by Comparative Example 4 of the present invention under 471 nm blue light excitation.

[0045] Figure 12 Shows a schematic diagram of the excitation spectrum of the far-red phosphor provided by Comparative Example 4 of the present invention measured by monitoring the 742 nm emission.

[0046] Figure 13 Shows a schematic diagram of the emission spectrum of the far-red phosphor provided by Embodiments 4-7 of the present invention under 471 nm blue light excitation.

[0047] Figure 14 Shows a schematic diagram of the excitation spectrum of the far-red phosphor provided by Embodiments 4-7 of the present invention measured by monitoring the 742 nm emission.

[0048] Figure 15 Shows a schematic diagram of the emission spectrum of the far-red phosphor provided by Embodiments 8-11 of the present invention under 471 nm blue light excitation.

[0049] Figure 16 Shows a schematic diagram of the excitation spectrum of the far-red phosphor provided by Embodiments 8-11 of the present invention measured by monitoring the 742 nm emission.

[0050] Figure 17 Shows a schematic diagram of the emission spectrum of the far-red phosphor provided by Embodiments 12-14 of the present invention under 471 nm blue light excitation.

[0051] Figure 18 Shows a schematic diagram of the excitation spectrum of the far-red phosphor provided by Embodiments 12-14 of the present invention measured by monitoring the 742 nm emission.

[0052] Figure 19 Shows a schematic diagram of the emission spectrum of the far-red phosphor provided by Embodiments 15-18 of the present invention under 471 nm blue light excitation.

[0053] Figure 20Schematic diagram showing the excitation spectrum of the far-red phosphor provided in Embodiments 15-18 of the present invention measured by monitoring the 742 nm emission.

[0054] Figure 21 Schematic diagram showing the emission spectrum of the far-red phosphor provided in Embodiments 19-21 of the present invention under 471 nm blue light excitation.

[0055] Figure 22 Schematic diagram showing the excitation spectrum of the far-red phosphor provided in Embodiments 19-21 of the present invention measured by monitoring the 742 nm emission.

[0056] Figure 23 Schematic diagram showing a retinal section of a mouse cultured under light-shielded conditions in Test Example 2 (wherein, INL is the inner retinal layer and ONL is the outer retinal layer).

[0057] Figure 24 Schematic diagram showing a retinal section of a mouse cultured under blue LED irradiation in Test Example 2 (wherein, INL is the inner retinal layer and ONL is the outer retinal layer).

[0058] Figure 25 Schematic diagram showing a retinal section of a mouse cultured under irradiation of a blue LED + a far-red LED encapsulated with the phosphor Gd3(Ga 0.96 Cr 0.04 )5O 12 prepared in Example 1 (wherein, INL is the inner retinal layer and ONL is the outer retinal layer). Detailed Description of the Invention

[0059] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0060] In the following examples, the raw materials used for preparing the far-red phosphor include:

[0061] Gd2O3 (99.99%), Dy2O3 (99.99%), Er2O3 (99.99%), Lu2O3 (99.99%), Sm2O3 (99.99%), Y2O3 (99.99%), H3BO3 (99.5%) and Cr2O3 (99.0%).

[0062] Example 1

[0063] This embodiment provides a far-red light LED device, which is prepared by titrating a mixture of Gd3(Ga 0.96 Cr 0.04 )5O 12 and transparent silica gel on a blue LED chip with a peak emission wavelength of 450 nm after defoaming and degassing, and then baking and curing;

[0064] The dosage ratio of Gd3(Ga 0.96 Cr 0.04 )5O 12 to the transparent silica gel is 1:0.4.

[0065] The preparation method of Gd3(Ga 0.96 Cr 0.04 )5O 12 includes:

[0066] The first step: Grind and mix evenly the raw materials containing Cr 3+ , the raw materials containing element Ga, the raw materials containing element Gd, and boric acid, and perform the first calcination to obtain the first-step product;

[0067] The second step: Grind the first-step product, then perform the second calcination, and perform crushing, grinding, water washing, filtration, and drying treatments to obtain the far-red phosphor.

[0068] The operating conditions of the first calcination include: carried out in air, heated to 200 °C at a rate of 5 °C / min, held for 0.5 hour, then heated to 500 °C at a rate of 5 °C / min, held for 2 hours, powered off, and cooled to 25 °C with the furnace;

[0069] The operating conditions of the second calcination include: carried out in air, heated to 900 °C at a rate of 5 °C / min, held for 2 hours, then heated to 1400 °C at a rate of 5 °C / min, held for 8 hours, then cooled to 600 °C at a rate of 5 °C / min, powered off, and cooled to 25 °C with the furnace;

[0070] The addition amount of boric acid is 1.0 wt% of the total mass of the raw materials used to prepare the far-red phosphor.

[0071] The emission spectrum and related parameters of the LED device in this embodiment are as shown in Figure 3 , 4 . It can be seen from Figure 3 that the emission wavelength of this device covers the main range of 650 - 950 nm, and the peak emission wavelength of the LED device redshifts from 732 nm (20 mA) to 756 nm (280 mA) with the increase of current. Figure 4Give the relationship between the photoelectric conversion efficiency and the driving current of the device. At a driving current of 20 mA, the photoelectric conversion efficiency reaches 33.51%; at a driving current of 100 mA, the radiant optical power is 75.91 mW and the photoelectric conversion efficiency is 25.91%; at a driving current of 280 mA, the radiant optical power reaches 177.2 mW.

[0072] Compare Figure 3 the emission spectrum of the LED device shown with the absorption spectrum of cytochrome c oxidase, as Figure 5 shown. It can be found that the emission spectrum of the LED device of the present invention can effectively cover the absorption peaks of Cu Bred and Cu Aoxid in cytochrome c oxidase.

[0073] Example 2-3

[0074] Example 2-3 provides far-red phosphors. The difference between Example 2-3 and Example 1 is only that: the far-red phosphors are Y3(Ga 0.96 Cr 0.04 )5O 12 and Lu3(Ga 0.96 Cr 0.04 )5O 12 .

[0075] Figure 6 And Figure 7 respectively give the emission spectra of the phosphors Gd3(Ga 0.96 Cr 0.04 )5O 12 , Y3(Ga 0.96 Cr 0.04 )5O 12 , Lu3(Ga 0.96 Cr 0.04 )5O 12 under 471 nm blue light excitation and the excitation spectra collected by monitoring their strongest emission peaks. It can be found that the one with the strongest luminescence is Gd3(Ga 0.96 Cr 0.04 )5O 12 . The peak emission wavelengths of Y3(Ga 0.96 Cr 0.04 )5O 12 and Lu3(Ga 0.96 Cr 0.04 )5O 12 can be adjusted in the range of 712 - 756 nm with the change of components.

[0076] Example 4-7

[0077] Example 4-7 provides far-red phosphors, and its chemical formula is: Gd3(Ga 1-xCr x )5O 12 , where x is 0.03 (3%), 0.04 (4%), 0.05 (5%), and 0.06 (6%) respectively.

[0078] The preparation method of the far - red phosphor of Examples 4 - 7 is the same as that of Example 1.

[0079] The emission spectra and excitation spectra of the far - red phosphors of Examples 4 - 7 are as Figure 13 , 14 shown. It can be seen from Figure 13 , 14 that the far - red phosphor with the best emission is Gd3(Ga 0.96 Cr 0.04 )5O 12 of Example 1, where x = 0.04.

[0080] Examples 8 - 11

[0081] Examples 8 - 11 provide the far - red phosphor Gd3(Ga 0.96 Cr 0.04 )5O 12 . The difference between Examples 8 - 11 and Example 1 is only that: the second heating temperature in the second calcination operation is different, which are 1300, 1350, 1400, and 1450 °C respectively, and the heat preservation time is 6 hours;

[0082] The emission spectra and excitation spectra of the far - red phosphors of Examples 8 - 11 are as Figure 15 , 16 shown. It can be seen from Figure 15 , 16 that the best temperature for the second heating in the second calcination operation is 1400 °C.

[0083] Examples 12 - 14

[0084] Examples 12 - 14 provide the far - red phosphor Gd3(Ga 0.96 Cr 0.04 )5O 12 . The difference between Examples 12 - 14 and Example 1 is only that: the second heating and heat preservation time in the second calcination operation is different, which are 4h, 6h, and 10h respectively;

[0085] The emission spectra and excitation spectra of the far - red phosphors of Examples 12 - 14 are as Figure 17 , 18 shown. It can be seen from Figure 17 , 18 that the best heat preservation time for the second heating in the second calcination operation is 8h of Example 1.

[0086] Examples 15 - 18

[0087] Examples 15 - 18 provide a far - red phosphor Gd3(Ga 0.96 Cr 0.04 )5O 12 , the difference between Examples 15 - 18 and Example 1 is only that: the flux is aluminum fluoride, barium fluoride, ammonium chloride and boric acid, and the addition amounts of aluminum fluoride, barium fluoride, ammonium chloride and boric acid are each independently 1% of the total mass of the raw materials used to prepare the far - red phosphor.

[0088] The emission spectra and excitation spectra of the far - red phosphors in Examples 15 - 18 are as Figure 19 、 20 shown. It can be seen from Figure 19 、 20 that the best flux is boric acid.

[0089] Examples 19 - 21

[0090] Examples 19 - 21 provide a far - red phosphor Gd3(Ga 0.96 Cr 0.04 )5O 12 , the difference between Examples 19 - 21 and Example 1 is only that: the boric acid is 0.5wt%, 1.5wt%, 2.0wt% of the total mass of the raw materials used to prepare the far - red phosphor respectively.

[0091] The emission spectra and excitation spectra of the far - red phosphors in Examples 19 - 21 are as Figure 21 、 22 shown. It can be seen from Figure 21 、 22 that the best addition amount of the boric acid is 1.0wt% of Example 1.

[0092] Comparative Examples 1 - 3

[0093] Comparative Examples 1 - 3 provide a phosphor. The difference between Comparative Examples 1 - 3 and Example 1 is only that: the far - red phosphor is Dy3(Ga 0.96 Cr 0.04 )5O 12 、Er3(Ga 0.96 Cr 0.04 )5O 12 、Sm3(Ga 0.96 Cr 0.04 )5O 12 .

[0094] Figure 6 and Figure 7 respectively give the phosphor Dy3(Ga 0.96 Cr 0.04 )5O 12, Er3(Ga 0.96 Cr 0.04 )5O 12 , Sm3(Ga 0.96 Cr 0.04 )5O 12 The emission spectra under 471 nm blue light excitation and the excitation spectra collected by monitoring their strongest emission peaks. It can be found from them that the luminescence intensities of Dy3(Ga 0.96 Cr 0.04 )5O 12 , Er3(Ga 0.96 Cr 0.04 )5O 12 , Sm3(Ga 0.96 Cr 0.04 )5O 12 are extremely weak and are not suitable as far - red phosphors.

[0095] Comparative Example 4

[0096] This comparative example provides a phosphor. The difference between this comparative example and Example 1 is only that: 0.1% and 0.5% of Ce are additionally added to the Gd3(Ga 0.96 Cr 0.04 )5O 12 phosphor to synthesize Gd3(Ga 0.96-y Cr 0.04 Ce y )5O 12 (y = 0.001, 0.005). Judging from the emission and excitation spectra shown in Figure 11 and 12 , although only 0.1% and 0.5% of Ce are added, it causes a significant decrease in the luminescence intensity.

[0097] Test Example 1

[0098] This test example compares the phosphors Gd3(Ga 0.96 Cr 0.04 )5O 12 , Y3(Ga 0.96 Cr 0.04 )5O 12 , Lu3(Ga 0.96 Cr 0.04 )5O 12 in Example 1 - 3 with the solar spectrum shown in Figure 1 and 2 and the solar spectrum under the shade of a tree respectively, as shown in Figure 8 and 9 , indicating that the phosphors of the present invention can better meet the requirements. From the perspective of luminescence thermal stability, for Gd3(Ga 0.96 Cr 0.04 )5O12 , Y3(Ga 0.96 Cr 0.04 )5O 12 , Lu3(Ga 0.96 Cr 0.04 )5O 12 By comparing three kinds of phosphors, it can be found that Gd3(Ga 0.96 Cr 0.04 )5O 12 has the best luminescence thermal stability, as shown in Figure 10 .

[0099] Test Example 2

[0100] The blue light component in the solar radiation spectrum is inevitable, as shown in Figure 1 and 2 . In addition, whether it is the deep blue water or the deep blue sky, blue light is an important element for generating beautiful optical sensations. SD male mice weighing 200 - 220 grams were taken as experimental subjects. In order to simulate the artificial living environment, the mice were cultured respectively (a) in a light-shielded dark environment, (b) in a blue light illumination environment, and (c) under the illumination condition of blue light + far red light (the far red light LED device of Example 1). Under the condition that other conditions are exactly the same, the three groups of mice were illuminated for 4 hours every day, and the rest of the time maintained normal light and dark changes for one week continuously. Two days after stopping the illumination, the eyeball retinas of the mice were taken for HE staining to observe the changes in the retinal structure of each group of mice (wherein, INL is the inner nuclear layer of the retina, and ONL is the outer nuclear layer of the retina).

[0101] Compared with the retinal structure of the mice under the light-shielding treatment (a), as shown in Figure 23 and 24 , after the blue light LED treatment (b), the thickness of the inner and outer layer cells of the mouse retina becomes smaller, and the arrangement of the cells is irregular, indicating that blue light affects the normal physiological activities of retinal cells and even causes the death of retinal cells. By comparing Figure 25 and 24 , it can be known that when far red light (c) is applied while irradiating with blue light LED, the thickness of the inner and outer layer cells of the mouse retina significantly thickens, and the arrangement of the retinal cells is tight and regular. This test example shows that the far red light LED device of the present invention has the effect of protecting the retina and can promote the damage repair and regeneration of retinal cells.

[0102] The above has described the embodiments of the present invention. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. Application of far-red light LED device as a light source for preventing and treating juvenile myopia, characterized in that, The far-red light LED device is prepared by mixing a far-red light phosphor, transparent silica gel, and optionally a red light phosphor, and encapsulating through an encapsulation process; The chemical formula of the far-red phosphor is: RE3(Ga 1-x Cr x )5O 12 , where RE is Gd and x = 0.

04.

2. The application according to claim 1, wherein, The preparation method of the far-red light phosphor includes: Step 1: Grind and mix evenly the raw materials containing Cr 3+ , the raw materials containing element Ga, the raw materials containing element RE, and the flux, and conduct the first calcination to obtain the product of the first step; Step 2: Grinding the product of the first step, then performing a second calcination, and performing crushing, grinding, washing, filtering, and drying treatments to obtain the far-red light phosphor.

3. The application according to claim 2, wherein, The raw material containing element RE is at least one of an oxide, nitrate, oxalate, and carbonate containing element RE; The raw material containing element Cr 3+ is at least one of an oxide, nitrate, oxalate, and carbonate containing element Cr 3+ ; The raw material containing element Ga is at least one of an oxide, nitrate, oxalate, and carbonate containing element Ga.

4. The application according to claim 2, wherein, The operating conditions of the first calcination include: performing in air, heating to 100 - 300 °C at a rate of 3 - 10 °C / min, holding for 0.3 - 1 hour, then heating to 400 - 600 °C at a rate of 3 - 10 °C / min, holding for 1 - 3 hours, cutting off the power, and cooling in the furnace to 25 - 30 °C; The operating conditions of the second calcination include: performing in air, heating to 850 - 950 °C at a rate of 3 - 10 °C / min, holding for 0.5 - 2 hours, then heating to 1300 - 1450 °C at a rate of 3 - 8 °C / min, holding for 4 - 10 hours, then cooling to 300 - 800 °C at a rate of 3 - 10 °C / min, cutting off the power, and cooling in the furnace to 25 - 30 °C; The addition amount of the flux is 0.05 - 2.0 wt% of the total mass of the raw materials used to prepare the far-red light phosphor; The flux is at least one of aluminum fluoride, barium fluoride, ammonium chloride, and boric acid.

5. The application according to claim 4, wherein, The flux is boric acid.

6. The application according to claim 1, wherein, The emission wavelength range of the far-red light phosphor is 600 - 1000 nm, and the emission wavelength peak is 650 - 900 nm; The dosage ratio of the far-red light phosphor, the red light phosphor, and the transparent silica gel is 1:(0 - 0.05):(0.2 - 0.8); The chemical formula of the red phosphor is (Ca,Sr)AlSiN3:Eu 2+ , or, M2Si5N8:Eu 2+ , where M is at least one of Sr, Ca, Ba, and Mg.

7. The application according to claim 1, wherein The encapsulation process includes: titrating the mixture of the far-red light phosphor, transparent silica gel, and optionally the red light phosphor on a blue LED chip after defoaming and degassing, and baking and curing to obtain the far-red light LED device.

8. The application according to claim 7, wherein The emission wavelength peak of the blue LED chip is 440 - 480 nm.

9. The application according to any one of claims 1-8, wherein, The emission wavelength range of the far-red light LED device is 600 - 1000 nm, and the emission wavelength peak is 650 - 900 nm.

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