WO2020088162A1 - Wavelength conversion device and preparation method therefor, light emitting device, and projecting device - Google Patents

Abstract

A wavelength conversion device (100) and preparation method therefor, and a light emitting device and a projecting device using the wavelength conversion device (100). The wavelength conversion device (100) comprises a substrate (10), a diffuse reflection layer (20), and a red inorganic light emitting layer (30) that are stacked in sequence. The diffuse reflection layer (20) is formed by mixing reflection power and a silicone gum. The red inorganic light emitting layer (30) is formed by mixing and curing red fluorescent powder and water glass. The wavelength conversion device has good heat resistance and can bear high optical power density.

Description

Wavelength conversion device and preparation method thereof, light-emitting device and projection device Technical field

The invention relates to the technical field of lighting and projection, in particular to a wavelength conversion device and a preparation method thereof, and a light-emitting device and a projection device using the wavelength conversion device.

Background technique

In the prior art, the luminescent layer of the color wheel (that is, the wavelength conversion device) made of silica gel encapsulated phosphor has the advantages of high efficiency and simple process. Therefore, silica gel has become the preferred packaging method for the low power laser light source color wheel. However, with the development trend of portable light source products, the size of the light source is required to be smaller and smaller, especially the micro-projection light source, so the volume of the color wheel also needs to be continuously reduced, which makes the light power density of the light emitting layer of the color wheel The continuous improvement causes the light-emitting layer, especially the light-emitting layer in the red segment, that is, the light-emitting layer containing red phosphor to be prone to cracking and blackening.

Excessive power density of the excitation light makes the luminescent layer of the red segment of the color wheel more prone to cracking and blackening. The reason is that the luminescent layer containing the red phosphor is excited by the excitation light to produce the greatest thermal effect of red fluorescence, so the red phosphor is encapsulated The silica gel withstands the most heat. At present, silica gel can work for a long time under the condition of 200 ℃, but can only work for a short time under the condition of 250 ～ 300 ℃, and the thermal conductivity of silica gel is only 0.1 ～ 0.2W / mK, the heat dissipation effect is not good, causing red fluorescence. The silica gel in the light emitting layer is prone to aging and cracking.

Summary of the invention

In order to solve the technical problem that the red light-emitting layer in the existing wavelength conversion device cannot withstand higher optical power density, the present invention provides a wavelength conversion device with good heat resistance and capable of withstanding higher optical power density, which includes substrates stacked in sequence , A diffuse reflection layer and a red light-emitting inorganic layer; the diffuse reflection layer is formed by mixing reflective powder and organic silica gel; the red light-emitting inorganic layer is formed by mixing and curing red fluorescent powder and water glass.

In one embodiment, the reflective powder is selected from one or more of aluminum oxide, titanium oxide, magnesium oxide, and yttrium oxide.

In one embodiment, the red phosphor is (Sr, Ca) AlSiN ₃ : Eu ²⁺ .

In one embodiment, the wavelength conversion device further includes a protective layer, and the protective layer is located on a side of the inorganic light-emitting layer opposite to the substrate.

In one embodiment, the protective layer is an organic silica gel film, and the organic silica gel is phenyl silica gel or methyl silica gel.

The invention also provides a method for preparing a wavelength conversion device, including the following steps:

A mixture of reflective powder and organic silica gel is used to form a diffuse reflection layer on one surface of the substrate;

Put the substrate with the diffuse reflection layer into the container, and the side of the substrate opposite to the diffuse reflection layer is in contact with the bottom of the container;

Add a certain concentration of nitrate solution to the container;

Add a mixed solution of red phosphor and water glass to the container, and let it stand for a period of time to form a deposited film containing red phosphor on the surface of the diffuse reflection layer; and

The cured deposited film forms a cured film containing red phosphor on the surface of the diffuse reflection layer.

In one embodiment, the reflective powder is selected from one or more of aluminum oxide, titanium oxide, magnesium oxide, and yttrium oxide.

In one embodiment, the nitrate solution is one or more of barium nitrate solution, calcium nitrate solution, strontium nitrate solution, and aluminum nitrate solution.

In one embodiment, the concentration of the nitrate solution is 0.05% to 0.1%.

In one embodiment, the water glass is one or a mixture of potassium silicate solution and sodium silicate solution.

In one embodiment, curing the deposited film is to absorb the supernatant and dry the deposited film to form a layer of the cured film containing red phosphor on the surface of the substrate.

In one embodiment, the drying includes the steps of first performing preliminary drying at a temperature of 40-80 ° C, and then continuing drying at a temperature of 100-200 ° C.

In one embodiment, the preparation method of the wavelength conversion device further includes the following step: coating a layer of organic silica gel on the surface of the cured film.

In one embodiment, the organic silica gel is phenyl silica gel or methyl silica gel.

The present invention also provides a light-emitting device including an excitation light source and the wavelength conversion device in any of the above embodiments.

The invention also provides a projection device including the above-mentioned light-emitting device.

The wavelength conversion device provided by the present invention uses a red light inorganic luminescent layer to replace the red segment luminous layer made of silica gel encapsulated red phosphor in the prior art, can withstand a greater excitation light power density, and is beneficial to the market for reducing the volume of the light source Demand, in addition, the output red light obtained has higher color purity and brightness. The preparation method of the wavelength conversion device provided by the invention is to solidify the water glass at low temperature for encapsulation, which can keep the efficiency of the red phosphor powder without loss.

BRIEF DESCRIPTION

FIG. 1 is a schematic structural diagram of a wavelength conversion device according to an embodiment of the present invention.

FIG. 2 is a schematic structural diagram of a wavelength conversion device according to another embodiment of the present invention.

FIG. 3 is a flowchart of the method for manufacturing the wavelength conversion device shown in FIG. 1.

FIG. 4 shows the results of changes in the luminous flux and color coordinates of the red light emitted by the wavelength conversion device and the color wheel using silica gel-encapsulated phosphors with the excitation light power.

FIG. 5 is a comparison spectrum diagram of the red light emitted by the wavelength conversion device provided in the embodiment of FIG. 4 and the color wheel using a silica gel-encapsulated phosphor at an excitation light power of 7.2W.

FIG. 6 is a comparison spectrum diagram of the red light emitted by the wavelength conversion device provided in the embodiment of FIG. 4 and a color wheel using a silica gel-encapsulated phosphor at an excitation light power of 10.7 W.

FIG. 7 is a comparison spectrum diagram of the red light emitted by the wavelength conversion device provided in the embodiment of FIG. 4 and the color wheel using silica gel-encapsulated phosphors when the excitation light power is 12.2W.

Symbol description of main components

Wavelength conversion device 100

Substrate 10

Diffuse reflection layer 20

Red phosphorescent layer 30

Protection layer 40

The following specific embodiments will further illustrate the present invention with reference to the above drawings.

detailed description

Please refer to FIG. 1, which is a schematic structural diagram of a wavelength conversion device 100 according to an embodiment of the present invention. The wavelength conversion device 100 provided by this embodiment includes a substrate 10, a diffuse reflection layer 20, and a red light-emitting inorganic light-emitting layer 30 that are sequentially stacked. In practical applications, the substrate 10 rotates at a high speed driven by a driving member such as a motor, so that the incident excitation light enters different regions of the substrate 10. When the excitation light enters the area where the red light-emitting inorganic light emitting layer 30 is located, the excitation light can excite the red fluorescent material to generate red fluorescence, thereby realizing the wavelength conversion of the light.

Specifically, the substrate 10 is a metal plate with high thermal conductivity, such as an aluminum plate, an aluminum nitride plate, and an aluminum oxide plate. In addition, in order to improve the thermal conductivity and light reflectivity, silver can also be plated on the surfaces of the aluminum plate, aluminum nitride plate, and aluminum oxide plate. Because the excitation light excites the fluorescent material to generate fluorescence, it is accompanied by a large amount of heat. Therefore, the substrate 10 not only has a load-bearing effect and rotates at a high speed in actual application, but also should have a good heat conduction effect. The accompanying heat is rapidly conducted and diffused.

The diffuse reflection layer 20 is made of reflective powder mixed with organic silica gel. The reflective powder is selected from one or more of aluminum oxide, titanium oxide, magnesium oxide, and yttrium oxide. As the organic silica gel, phenyl silica gel or methyl silica gel can be used. The red phosphor layer 30 is formed by mixing and curing red phosphor and water glass. The red phosphor is preferably (Sr, Ca) AlSiN ₃ : Eu ²⁺ . The chemical formula of water glass is R ₂ O · nSiO ₂ , where R ₂ O is an alkali metal oxide, n is the ratio of the number of moles of silica and alkali metal oxide, and is called the friction number of water glass.

It should be noted that the diffuse reflection layer 20 can diffuse the spot formed on the substrate 10 by the excitation light through the red light-emitting phosphor layer 30 to a certain extent, so as to improve the utilization efficiency of the red phosphor and enhance the luminous efficiency. In addition, the adhesion of the red phosphor layer 30 on the diffuse reflection layer 20 is better than that directly fabricated on the substrate 10.

Please refer to FIG. 2, which is a schematic structural diagram of a wavelength conversion device 100 according to another embodiment of the present invention. The wavelength conversion device 100 further includes a protective layer 40, which is located on the side of the red phosphorescent layer 30 opposite to the substrate 10.

Specifically, the protective layer 40 is an organic silica gel film, which may be phenyl silica gel or methyl silica gel, preferably phenyl silica gel.

Please refer to FIG. 3, which is a flowchart of the method for manufacturing the wavelength conversion device 100 shown in FIG. 1. The preparation method of the wavelength conversion device 100 specifically includes the following steps:

S101: forming a diffuse reflection layer 20 on one surface of the substrate 10 by using a mixture of reflective powder and organic silica gel;

S102: Put the substrate 10 with the diffuse reflection layer 20 into the container and the side of the substrate 10 facing away from the diffuse reflection layer 20 is in contact with the bottom of the container,

S103: Add a certain concentration of nitrate solution to the container;

S104: Add a mixed solution of red phosphor and water glass to the container and disperse it ultrasonically, and let it stand for a period of time to form a deposited film containing red phosphor on the surface of the diffuse reflection layer 20;

S105: curing the deposited film to form a cured film containing red phosphor on the surface of the diffuse reflection layer 20.

It can be understood that the cured film formed on the surface of the diffuse reflection layer 20, that is, the red light-emitting phosphor layer 30, therefore, the red light-emitting phosphor layer 30 uses a glass-encapsulated red phosphor process.

Specifically, the nitrate solution may be one or more of barium nitrate solution, calcium nitrate solution, strontium nitrate solution, and aluminum nitrate solution. Its function is to form a precipitant with water glass to increase the red light emitting layer 30 Adhesion. Preferably, the concentration of the nitrate solution is 0.05% to 0.1%. It should be noted that too high a concentration of the nitrate solution will reduce the light efficiency, and if it is too low, the adhesion of the red light-emitting phosphor layer 20 will be deteriorated.

The water glass may be a potassium silicate solution or a sodium silicate solution, or a mixed solution of potassium silicate and sodium silicate. In this embodiment, potassium silicate solution is used for the water glass, because potassium silicate has good moisture-proof stability. It should be noted that this embodiment adopts the deposition method, therefore, the concentration of the potassium silicate solution has a great influence, preferably 2 to 6%, too high a concentration is not conducive to dispersion, and too low results in the red light emitting layer 20 Adhesion becomes poor.

In step S104, the use of ultrasonic dispersion enables the red phosphor and potassium silicate to form a uniform dispersion system, making the deposited film more uniform. It is necessary to allow sufficient time for the mixed system of red phosphor and potassium silicate to deposit, and at the same time, the precipitation agent barium silicate is fully reacted and generated.

In step S105, a layer of cured film containing red phosphor can be formed by absorbing the supernatant and drying the deposited film. It can be understood that when the supernatant liquid is sucked, care must be taken to prevent the uniformity of the deposited film from being damaged.

Specifically, drying the deposited film includes the following steps: firstly perform preliminary drying at a temperature of 40-80 ° C, and then continue drying at a temperature of 100-200 ° C. Among them, the initial drying at a temperature of 40 ~ 80 ℃ can make most of the water volatilize, and drying at a lower temperature can ensure the compactness of the deposited film; continue drying at a temperature of 100 ~ 200 ℃ It can further evaporate water and make the deposited film solidify as a cured film. In this embodiment, the drying process of the deposited film includes: drying at a temperature of 50 ° C for 1 hour, and then drying at a temperature of 150 ° C for 1 hour.

Further, the preparation method of the wavelength conversion device 100 further includes the following steps: S106: coat a layer of organic silica gel on the surface of the cured film. It can be understood that a layer of organic silica gel coated on the surface of the cured film is the protective layer 40.

It should be pointed out that the red phosphor is generally a nitride with low thermal stability, which is prone to oxidative decomposition at 600 ° C, and it is easy to chemically react with the glass melt at high temperatures to lose efficiency, making the application of glass encapsulation greatly limits. The preparation method of the wavelength conversion device 100 provided by the present invention is a water glass package cured at a low temperature of 100-200 ° C. At this low temperature, the red light-emitting phosphor layer 30 can maintain the efficiency of the red phosphor without loss.

In order to verify the performance comparison of the luminous flux and color coordinates of the red light emitted by the wavelength conversion device 100 provided in the embodiment of the present invention and the fluorescent pink wheel encapsulated with silicone in the prior art, the color of the phosphor encapsulated in silicone in the prior art The wheel is used as a standard sample, and the wavelength conversion devices 100 with the numbers 1 #, 2 #, 3 #, 4 #, 5 #, and 6 # provided by the embodiment of the present invention have excitation light powers of 7.2W and 10.7W, respectively. At 12.2W, the luminous flux and color coordinates of the emitted red light are measured. The results are shown in Figure 4.

Specifically, the sample composition of the wavelength conversion devices 100 numbered 1 #, 2 #, and 3 # includes a substrate 10, a red light-emitting phosphor layer 30, and a protective layer 40, wherein the substrate 10 is a silver-plated aluminum plate. It should be noted that the preparation process of the wavelength conversion device 100 with the numbers 1 #, 2 #, and 3 # omits step S101, directly places the substrate 10 in the container, and sequentially forms the step S102-S106 to include only the substrate 10, red The wavelength conversion device 100 of the photo-inorganic light-emitting layer 30 and the protective layer 40.

The sample composition of the wavelength conversion devices 100 with the numbers 4 #, 5 #, and 6 # includes the substrate 10, the diffuse reflection layer 20, the red light-emitting phosphor layer 30, and the protective layer 40. Therefore, the wavelength conversion devices 100 with the numbers 1 # to 6 # have the same substrate 10, red light-emitting phosphor layer 30, and protective layer 40. Compared with the wavelength conversion device 100 provided in the embodiment, the silicone-encapsulated fluorescent pink wheel as a standard sample also uses a silver-plated aluminum plate, and a diffuse reflection bottom is provided between the silver-plated aluminum plate and the light-emitting layer prepared by the silicone-encapsulated phosphor.

Further, when the excitation optical powers are 7.2W, 10.7W and 12.2W, respectively, the wavelength conversion devices 100 with the numbers 1 # and 4 # provided by the embodiment of the present invention and the fluorescent pink wheel with silica gel package as the standard sample are emitted The spectra of red light are compared, and the results are shown in Figures 5 to 7, respectively.

Comprehensive analysis of the results shown in FIGS. 4 to 7 shows that when the excitation light power is low, for example, when the optical power is 7.2 W, the luminous flux of the wavelength conversion device 100 provided by the embodiment of the present invention is lower than that of the silicone-encapsulated fluorescent pink wheel, but With the increase of the excitation optical power, for example, when the optical power is 10.7W and 12.2W, the luminous flux of the wavelength conversion device 100 provided by the embodiment of the present invention is higher than that of the silicone-encapsulated fluorescent pink wheel. Therefore, the wavelength conversion device 100 provided by the embodiment of the present invention is more suitable for the case where the excitation light power density is large, and can be used as a microprojection light source with a power of about 10W.

It is worth noting that the color coordinate stability of the output red light of the wavelength conversion device 100 provided by the embodiment of the present invention is better, and the color purity and brightness are higher. In addition, the performance of the red light emitted by the wavelength conversion device 100 with the numbers 4 # to 6 # is better than the wavelength conversion device 100 with the numbers 1 # to 3 #, because the diffuse reflection layer 20 can transmit the excitation light The spot formed on the substrate 10 through the red-light phosphor layer 30 is diffused to a certain extent to improve the utilization efficiency of the red phosphor and enhance the luminous efficiency. In addition, the adhesion of the red-light phosphor layer 30 to the diffuse reflection layer 20 The strength is better than that directly fabricated on the substrate 10, which can avoid the blackening of the silver layer of the silver-plated aluminum plate at high temperature and make the reliability higher.

Further, the present invention further provides a light-emitting device including an excitation light source and a wavelength conversion device 100, wherein the wavelength conversion device 100 has the structure and function in the above-mentioned embodiment. The light-emitting device can be applied to projection and display systems, such as liquid crystal displays (LCD, Liquid Crystal) or digital light path processor projectors (DLP, Digital Light Processor); can also be applied to lighting systems, such as car lights, stage lights ; Can also be applied in the field of 3D display technology.

Further, the present invention also provides a projection device, which includes the light-emitting device of any of the above embodiments.

The above are only the embodiments of the present invention, and therefore do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present invention, or directly or indirectly used in other related technical fields, The same reason is included in the patent protection scope of the present invention.

Claims (16)

1. A wavelength conversion device, characterized in that it includes a substrate, a diffuse reflection layer and a red light-emitting inorganic layer sequentially stacked; the diffuse reflection layer is made of a mixture of reflective powder and organic silica gel; the red light-emitting inorganic layer is composed of The red fluorescent powder is mixed with water glass and solidified.
2. The wavelength conversion device according to claim 1, wherein the reflective powder is selected from one or more of aluminum oxide, titanium oxide, magnesium oxide, and yttrium oxide.
3. The wavelength conversion device according to claim 1, wherein the red phosphor is (Sr, Ca) AlSiN ₃ : Eu ²⁺ .
4. The wavelength conversion device according to claim 1, wherein the wavelength conversion device further comprises a protective layer, the protective layer being located on a side of the inorganic light emitting layer opposite to the substrate.
5. The wavelength conversion device according to claim 4, wherein the protective layer is an organic silica gel film, and the organic silica gel is phenyl silica gel or methyl silica gel.
6. A method for preparing a wavelength conversion device, characterized in that it includes the following steps:

   A mixture of reflective powder and organic silica gel is used to form a diffuse reflection layer on one surface of the substrate;

   Put the substrate with the diffuse reflection layer into the container, and the side of the substrate opposite to the diffuse reflection layer is in contact with the bottom of the container;

   Add a certain concentration of nitrate solution to the container;

   Add a mixed solution of red phosphor and water glass to the container, and let it stand for a period of time to form a deposited film containing red phosphor on the surface of the diffuse reflection layer; and

   The cured deposited film forms a cured film containing red phosphor on the surface of the diffuse reflection layer.
7. The preparation method according to claim 6, wherein the reflective powder is selected from one or more of aluminum oxide, titanium oxide, magnesium oxide, and yttrium oxide.
8. The preparation method according to claim 6, wherein the nitrate solution is one or more of barium nitrate solution, calcium nitrate solution, strontium nitrate solution and aluminum nitrate solution.
9. The preparation method according to claim 6, wherein the concentration of the nitrate solution is 0.05% to 0.1%.
10. The preparation method according to claim 6, wherein the water glass is one or a mixture of potassium silicate solution and sodium silicate solution.
11. The preparation method according to claim 6, characterized in that curing the deposited film is by absorbing the supernatant and drying the deposited film to form a layer of red phosphor on the surface of the substrate Cured film.
12. The preparation method according to claim 11, wherein the drying comprises the steps of: performing preliminary drying at a temperature of 40-80 ° C, and then continuing drying at a temperature of 100-200 ° C.
13. The preparation method according to claim 6, further comprising the step of: coating a layer of organic silica gel on the surface of the cured film.
14. The preparation method according to claim 13, wherein the organic silica gel is phenyl silica gel or methyl silica gel.
15. A light-emitting device comprising an excitation light source and the wavelength conversion device according to any one of claims 1 to 5.
16. A projection device comprising the light-emitting device according to claim 15.

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