Composite fluorescent sheet as well as preparation method and application thereof

Abstract

The invention discloses a composite fluorescent sheet as well as a preparation method and application thereof. The composite fluorescent sheet comprises more than two fluorescent sheet materials, and the more than two fluorescent sheet materials form a planar sheet structure which takes one of the fluorescent sheet materials as a central fluorescent sheet and the other fluorescent sheet materials surround outwards layer by layer in the same plane. According to the invention, the composite fluorescent sheet is designed by adopting the ring which generates fluorescence of different light colors, so that the optimal solutions of luminous efficiency and color rendering performance are realized, the reabsorption among different fluorescent materials is greatly reduced, and the luminous efficiency of the fluorescent ceramic material is ensured while high color rendering performance is obtained. Meanwhile, the material can bear irradiation of a laser light source with the power density of 1-20 W / mm < 2 >, and has excellent light-emitting stability; and the scattering of the laser light source is greatly improved, so that the emergent light is more uniform.

Description

Technical Field

[0001] The present invention belongs to the technical field of lighting materials, and in particular relates to a composite fluorescent sheet and a preparation method and application thereof. Background Art

[0002] In recent years, laser display technology has been widely used in product fields such as movie projection, commercial projection, home display and engineering projection, and is rapidly seizing the market share of traditional projection display light sources such as xenon lamps and LED light sources. Compared with white light LEDs, white light semiconductor lasers (LDs) have the advantages of higher luminous efficiency, less energy consumption, and better directionality, and are expected to become a new generation of lighting sources. In white light LDs, the ideal solution is to mix blue light LD chips with green-yellow phosphors and orange or red phosphors to achieve white light emission. However, in this packaging method, organic materials such as resins have poor heat dissipation performance and heat accumulation effects. They are very easy to age and deteriorate at high temperatures, causing light decay and color drift, which greatly reduces the service life of white light LDs. In particular, since LD excitation light power is larger and the excitation area is smaller, the packaging method that only uses phosphors directly affects the working efficiency and service life of the device, greatly limiting its development in the field of high-power white light LDs.

[0003] Currently, the fluorescent films are mainly monochromatic fluorescent films (such as YAG yellow light), which are combined with blue light LD to obtain white light LD. However, most of them have low color rendering index of white light and can hardly meet the increasing needs for general lighting or backlighting. Summary of the invention

[0004] The present invention provides a composite fluorescent sheet and a preparation method and application thereof, aiming to meet the use needs in the field of backlight display and lighting, and further provides a new fluorescent sheet structure application product form, which can achieve high luminous efficiency and high color rendering index in lighting applications; and can achieve high color gamut in backlight display applications.

[0005] The present invention provides a composite fluorescent sheet, comprising two or more fluorescent sheet materials, wherein the two or more fluorescent sheets form a planar sheet structure in the same plane with one of the fluorescent sheet materials as the central fluorescent sheet and the other fluorescent sheet materials surrounding the central fluorescent sheet layer by layer.

[0006] In the composite fluorescent sheet described above, the remaining fluorescent ceramic materials are arranged to surround the central fluorescent sheet layer by layer to form a ring-shaped surrounding plane sheet structure that expands layer by layer with the central fluorescent sheet as the center.

[0007] The shape of the central fluorescent sheet is a circular to elliptical circular shape; the remaining fluorescent sheets surround the central fluorescent sheet and extend outward in equal or unequal proportions. The shape of the outermost fluorescent sheet material is limited according to the needs of the actual application scenario.

[0008] The composite fluorescent sheet mentioned above, the fluorescent sheet material at least includes a fluorescent sheet material that emits any one of yellow light, red light, reddish-yellow light, green light or yellow-green light under the excitation of a blue light LED or a blue light LD.

[0009] The substrate of the fluorescent sheet material is glass, ceramic or high temperature resistant resin.

[0010] The substrate of the fluorescent sheet material is an aluminum oxide or aluminum nitride ceramic substrate.

[0011] In the composite fluorescent sheet described above, adjacent fluorescent sheet material layers are connected by means of clamping, bonding, welding or sintering; there is no gap between adjacent fluorescent sheet material layers or the gap width is less than 3 microns.

[0012] The composite fluorescent sheet described above, wherein the fluorescent sheet material is selected from LuAG:Ce 3+ Fluorescent ceramics, YAG:Ce 3+ Fluorescent ceramics, La 3 Si 6 N 11 : Ce 3+ Fluorescent ceramics, α-sialon fluorescent ceramics, β-sialon fluorescent ceramics, γ-AlON fluorescent ceramics, CaAlSiN 3 :Eu 2+ Fluorescent ceramics, (Sr,Ca)AlSiN 3 :Eu 2+ Fluorescent ceramic or SrLiAl 3 N 4 :Eu 2+ At least two of the fluorescent ceramics.

[0013] Specifically, the first fluorescent ceramic layer is LuAG:Ce 3+ Fluorescent ceramics or β-sialon fluorescent ceramics; The LuAG:Ce 3+ The raw materials and molar ratio of the fluorescent ceramics can be Lu a (Al b Ga c ) 12 :xCe 3+ , 2.8≤a≤3, 2≤b≤5, 0≤c≤3, 0.001≤c≤0.2.

[0014] The raw materials and molar ratio of the β-sialon fluorescent ceramic can be Si 6-z Al z OzN 8-z : x Eu, 0.1≤z≤0.3, 0.001≤x≤0.05.

[0015] The second fluorescent ceramic layer is La 3 Si 6 N 11 : Ce 3+ Fluorescent ceramics, including La 3 Si 6 N 11 : Ce 3+ The luminescent ceramic layer emits light in the wavelength range of 540 - 560 nm.

[0016] The preparation method of the composite fluorescent sheet described above, the preparation process of the composite fluorescent sheet is as follows: Step (1), preparing a core rod of a central fluorescent sheet material blank; Step (2), preparing a second fluorescent sheet slurry surrounding the central fluorescent sheet material; Step (3), applying the slurry prepared in step (2) to the surface of the core rod obtained in step (1) to obtain a composite fluorescent sheet green body material with a double-layer structure; Step (4), curing; Step (5), continue to prepare the slurry of the subsequent fluorescent sheet material, apply it to the surface of the core rod structure obtained by curing in the previous step, and cure it until the slurry coating and curing of the last fluorescent sheet material are completed; Step (6), slicing the obtained composite fluorescent sheet along a direction perpendicular to the radial direction to obtain a sheet-like composite fluorescent sheet.

[0017] Application of the composite fluorescent sheet described in any one of the above items as a wavelength conversion medium in the field of lighting.

[0018] An optical color wheel comprises any one of the composite fluorescent sheets described above.

[0019] A projection device comprises a laser light source and the above-mentioned optical color wheel, wherein the optical color wheel generates excitation light under the excitation of laser light generated by the laser light source.

[0020] The composite fluorescent sheet described in any one of the above items is used as a wavelength conversion medium in the field of backlight display.

[0021] A backlight display device comprises a backlight display light source and a light source conversion element, wherein the light source conversion element comprises the composite fluorescent sheet mentioned above. Beneficial Effects

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a composite fluorescent sheet structure of a novel structure, especially as an application that meets the requirements of fluorescent ceramic sheets. This structure breaks through the application form of traditional fluorescent ceramics, can match the lighting characteristics of light sources, and match fluorescent ceramics with different luminous properties in different layers of the structure to give full play to the optimal performance of each fluorescent ceramic layer.

[0023] 2. The present invention achieves the optimal solution for luminous efficiency and color rendering performance by adopting a ring-shaped design that generates fluorescence of different light colors to form a composite planar structure, thereby avoiding reabsorption between different fluorescent materials, obtaining high color rendering performance, and ensuring the luminous efficiency of the fluorescent ceramic material.

[0024] 3. Composite ceramics can withstand 1 ~ 20 W / mm 2 The irradiation of the laser light source with high power density has excellent luminous stability.

[0025] 4. The composite fluorescent ceramic provided by the present invention can further expand and enhance the application of fluorescent ceramics. For example, it can be used in the color wheel structure of existing projection equipment, which can greatly reduce the volume of the existing color wheel structure. It can also be used in the fields of micro laser lighting, laser projection, etc. to achieve high light efficiency, high color rendering, high color gamut and other characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Schematic diagram of the structure of the composite fluorescent sheet provided in Example 1 of the present invention.

[0027] Figure 2 : Schematic diagram of the structure of the composite fluorescent sheet provided in Example 1 of the present invention.

[0028] Figure 3 : Schematic diagram of composite fluorescent sheet slice.

[0029] Figure 4 : Application of the composite fluorescent sheet provided by the present invention.

[0030] Figure 5 : Application of the composite fluorescent ceramic provided by the present invention in lighting and backlight display.

[0031] Figure 6 : Application of the composite fluorescent ceramic provided by the present invention in lighting and backlight display. Implementation Example

[0032] In one embodiment of the present invention, a composite fluorescent sheet is provided, such as Figure 1As shown, it includes a first fluorescent sheet material 1 and a second fluorescent sheet material 2, which form a planar sheet structure with the first fluorescent sheet material 1 as the center and the second fluorescent sheet material 2 surrounding the first fluorescent sheet material 1 in the same plane. The first fluorescent sheet material 1 and the second fluorescent sheet material 2 can be connected by bonding, welding, sintering, etc. Under preferred conditions, the first fluorescent sheet material 1 and the second fluorescent sheet material 2 can be connected seamlessly by co-sintering, and when other connection methods are used, the width of the connection gap generally does not exceed 3 microns, otherwise it will affect the light output performance.

[0033] The composite fluorescent sheet provided in this embodiment is a composite fluorescent ceramic, which can be used in the field of illumination or backlighting excited by a blue light chip, wherein the first fluorescent sheet material 1 and the second fluorescent sheet material 2 can respectively select blue light to emit red light, red-yellow light, yellow light, green light or yellow-green light, so that the first fluorescent sheet material 1 and the second fluorescent sheet material 2 form white light under the excitation of the same blue light source. The materials that can be selected for the first fluorescent sheet material 1 and the second fluorescent sheet material 2 are CaAlSiN 3 :Eu 2+ Fluorescent ceramics, YAG:Ce 3+ Fluorescent ceramics, LuAG:Ce 3+ Fluorescent ceramics, La 3 Si 6 N 11 : Ce 3+ Fluorescent ceramics, α-sialon fluorescent ceramics, β-sialon fluorescent ceramics, γ-AlON fluorescent ceramics, (Sr,Ca)AlSiN 3 :Eu 2+ Fluorescent ceramic or SrLiAl 3 N 4 :Eu 2+ A type of fluorescent ceramic.

[0034] In this embodiment, the first fluorescent sheet material 1 and the second fluorescent sheet material 2 may also be made of fluorescent glass or other fluorescent materials such as organic fluorescent materials (organic resin) and the like.

[0035] The composite fluorescent sheet provided in this embodiment provides a new application structure of fluorescent materials, which breaks through the application form of existing laminated fluorescent sheets. When the excitation light source irradiates the composite fluorescent sheet of this embodiment, the excitation light source spot completely covers the entire composite fluorescent sheet, thereby allowing the excitation light source to pass through different fluorescent material layers (such as Figure 4 As shown in the schematic diagram), a preset color of light, such as white light, is finally obtained. This new structural form avoids the light loss caused by the excitation light source passing through different fluorescent layers in sequence, thereby improving the light efficiency, and the structure can be applied to a variety of scenarios, further expanding the scope of application.

[0036] Another embodiment 2 of the present invention provides a composite fluorescent sheet, such as Figure 2 As shown, it includes a third fluorescent sheet material 3, a fourth fluorescent sheet material 4 and a fifth fluorescent sheet material 5, wherein the third fluorescent sheet material 3 is the center, the fourth fluorescent sheet material 4 annularly surrounds the third fluorescent sheet material 3, and the fifth fluorescent sheet material 5 annularly surrounds the fourth fluorescent sheet material 4. The third fluorescent sheet material 3, the fourth fluorescent sheet material 4 and the fifth fluorescent sheet material 5 form a planar sheet structure in the same plane.

[0037] In this embodiment, the third fluorescent sheet material 3, the fourth fluorescent sheet material 4 and the fifth fluorescent sheet material 5 can be selected according to actual needs to select fluorescent sheet materials with different luminous colors and fluorescent sheet materials with different luminous properties. The radial dimensions of the third fluorescent sheet material 3, the fourth fluorescent sheet material 4 and the fifth fluorescent sheet material 5 can be in equal proportion or unequal proportion according to actual needs.

[0038] In other embodiment 3 of the present invention, according to the actual scene application requirements, the shape of the central fluorescent sheet material located in the center can be a circular to elliptical circular shape, or other shapes.

[0039] The composite fluorescent sheet provided by the present invention can be used for directly transmitting light from an excitation light source and reflecting light from an excitation light source (such as Figure 5 and Figure 6 In the application scenario of the schematic diagram shown in the figure).

[0040] The composite fluorescent sheet provided by the present invention can be used as a wavelength conversion medium in the field of lighting.

[0041] Specifically, it can continue to be applied in an optical color wheel in a projection device, and can also be applied in a backlight display device as a light source conversion element.

[0042] In another embodiment 4 of the present invention, a method for preparing a composite fluorescent sheet is provided, which is as follows: Step (1), preparing a core rod of a blank of a central fluorescent sheet material, wherein the core rod of the blank can be prepared by extruding the blank by an extruder; Step (2), preparing a second fluorescent sheet slurry surrounding the central fluorescent sheet material; preparing the second fluorescent sheet material into a slurry that can be coated, brushed or hung; Step (3), coating or brushing the slurry prepared in step (2) on the surface of the core rod obtained in step (1), or immersing the core rod in the slurry and then taking it out to coat the slurry, to obtain a composite fluorescent sheet green body material with a double-layer structure; Step (4), curing the composite fluorescent sheet green material finally obtained in step (3) by high temperature drying or the like; Step (5), continue to prepare the slurry of the subsequent fluorescent sheet material, and apply it to the surface of the core rod structure obtained by curing in the previous step, and cure it until the slurry coating and curing of the last fluorescent sheet material are completed; after the slurry coating of the last fluorescent sheet material in this step is completed, a curing treatment is performed in a corresponding manner according to the material properties to form a finished product. If the fluorescent sheet material is a fluorescent ceramic, it needs to be processed by debinding, hot pressing and sintering, etc. to finally obtain a ceramic.

[0043] Step (6), slicing the obtained composite fluorescent sheet along a direction perpendicular to the radial direction (such as Figure 3 A sheet-like composite fluorescent sheet is obtained.

[0044] Another embodiment 5 of the present invention provides a method for preparing a composite fluorescent ceramic sheet, and the specific preparation process is as follows: First, weigh 19.83 g of Al 2 O 3 Powder, 47.06 g Lu 2 O 3 powder, and 0.21 g of CeO 2 As a raw material, 0.4 g of MgO powder is weighed as a sintering aid, and then 12% of the weight of the dry powder is added with polyvinyl alcohol, 3% of oleic acid, 5% of deionized water, 7% of glycerol, and 8% of liquid paraffin, and then a mixer is started to mix and stir until a plastic clay mass is obtained; the plastic clay mass is placed in a vacuum extruder and extruded to obtain a ceramic rod-shaped blank; the extruded ceramic rod-shaped blank is placed on a wooden pallet, and then placed in an oven at 80 degrees Celsius for 8 hours for drying; Weigh 50 g of LSN powder, add 30 g of anhydrous ethanol and 0.25 g of dispersant SC-0505K, and mechanically mill for 8-12 hours to obtain a slurry with a viscosity of 360 mPa·s; The rod-shaped LuAG:Ce 3+ The ceramic is immersed in the LSN ceramic slurry, and the above steps are repeated until the slurry thickness is consistent with the radius of the mandrel; The composite fluorescent ceramic blank is placed in a resistance furnace for debinding treatment at a debinding temperature of 600 degrees Celsius, and finally hot-pressed sintering is performed at a sintering temperature of 1950°C, a pressure of 10 MPa, and a holding time of 10 hours. The composite fluorescent sheet is obtained by slicing perpendicular to the axial direction.

[0045] The fluorescent sheet materials of comparative example 1 are two fluorescent materials equivalent to those of embodiment 5, except that the structure is a laminated structure, and the thickness of each laminated structure is the same as the thickness of the composite fluorescent ceramic sheet of embodiment 5.

[0046] The composite fluorescent sheet prepared in the above embodiment has the following performance indicators: The prepared composite fluorescent sheet was excited by 460nm blue light LED and tested to have the following properties.

[0047] Fluorescent ceramic materials Power W Color temperature K Color Rendering Index Luminous efficiency (lm / W) This embodiment 5 6 3000 83 203 Comparative Example 1 6 3000 72 189 It can be seen from the above that the sheet structure provided by the present invention has superior performance compared to the laminated structure under the same conditions. This is because when the incident light passes through the fluorescent sheet of the laminated structure, it needs to pass through each layer of the fluorescent sheet in sequence. Due to the filtering effect of each layer on the light, the light enters each layer in sequence and causes light loss. The planar sheet structure provided by the present invention allows the incident light to pass through each layer of fluorescent material at the same time, and the layers will not affect each other, thereby avoiding the negative effect of light loss caused by the laminated structure.

[0048] Another embodiment 6 of the present invention provides a composite fluorescent ceramic sheet, and the preparation process thereof is as follows: First, weigh 26.38 g of Al 2 O 3 Powder, 55.13 g SrLiAl 3 N 4 :Eu 2+ Phosphor powder, weigh 0.6 grams of MgO powder as a sintering aid, then add 16% of polyvinyl alcohol, 4% of oleic acid, 6% of deionized water, 6% of glycerol, and 11% of liquid paraffin in weight equivalent to the weight of the above dry powder, then start the mixer to mix and stir until a plastic clay mass is obtained; place the plastic clay mass in a vacuum extruder and extrude it to obtain a ceramic rod-shaped blank; place the extruded ceramic rod-shaped blank on a wooden pallet, and then place it in an oven at 80 degrees Celsius for 8 hours for drying; Weigh 60 g of β-sialon phosphor powder, add 38 g of anhydrous ethanol and 0.31 g of dispersant SC-0505K, and mechanically ball mill for 8-12 hours to obtain LSN powder slurry with a viscosity of 372 mPa·s; Rod-shaped SrLiAl 3 N 4 :Eu 2+ The fluorescent ceramic is immersed in the β-sialon fluorescent ceramic slurry, and the above steps are repeated until the slurry thickness is 100% of the core rod radius. After completion, it is dried at 80 degrees Celsius for 8 hours; The composite fluorescent ceramic blank is placed in a resistance furnace for debinding treatment at a debinding temperature of 650 degrees Celsius, and finally hot-pressed sintering is performed at a sintering temperature of 1980°C, a pressure of 10 MPa, and a holding time of 10 hours.

[0049] The fluorescent sheet materials of Comparative Example 2 are two fluorescent ceramic materials equivalent to those of Example 6, except that the structure is a laminated structure, and the thickness of each layer of the laminated structure is the same as the thickness of the composite fluorescent ceramic sheet of Example 6.

[0050] The composite fluorescent ceramics prepared in the above examples, when excited by 460nm blue light, have the following performance indicators: Fluorescent ceramic materials Power W Color temperature K NTSC color gamut value% Example 6 6 3000 90 Comparative Example 2 6 3000 88 It can be seen from the above that the planar sheet structure provided by the present invention is more capable of providing or maintaining the unique high color gamut performance produced by the combination of the materials themselves, compared with the laminated structure, and the laminated structure will also have a slight performance loss compared with the sheet structure of the present invention.

Claims

1. A composite fluorescent sheet, characterized in that: It comprises two or more fluorescent sheet materials, wherein the two or more fluorescent sheet materials form a planar sheet structure in the same plane with one fluorescent sheet material as the central fluorescent sheet and the other fluorescent sheet materials surrounding it layer by layer.

2. The composite fluorescent sheet according to claim 1, characterized in that: The remaining fluorescent sheet materials are arranged outwardly layer by layer in a manner of forming a ring-shaped surrounding plane sheet structure that expands layer by layer with the central fluorescent sheet as the center.

3. The composite fluorescent sheet according to claim 1, characterized in that: Adjacent fluorescent sheet layers are connected by bonding, welding or sintering.

4. The composite fluorescent sheet according to claim 3, characterized in that: Adjacent fluorescent sheet material layers are connected without gaps or the width of the connection gap is less than 3 microns.

5. The composite fluorescent sheet according to any one of claims 1 to 4, characterized in that: The fluorescent sheet material at least includes a fluorescent sheet material that emits any one of yellow light, red light, red-yellow light, green light or yellow-green light under the excitation of a blue light LED or a blue light LD.

6. The composite fluorescent sheet according to claim 5, characterized in that: The substrate of the fluorescent sheet material is glass, ceramic or high temperature resistant resin.

7. The composite fluorescent sheet according to claim 6, characterized in that: The substrate of the fluorescent sheet material is an aluminum oxide or aluminum nitride ceramic substrate.

8. The composite fluorescent sheet according to claim 7, characterized in that: The fluorescent sheet material is selected from LuAG:Ce 3+ Fluorescent ceramics, YAG:Ce 3+ Fluorescent ceramics, La3Si6N 11 : Ce 3+ Fluorescent ceramics, α-sialon fluorescent ceramics, β-sialon fluorescent ceramics, γ-AlON fluorescent ceramics, CaAlSiN3:Eu 2+ Fluorescent ceramics, (Sr,Ca)AlSiN3:Eu 2+ Fluorescent ceramic or SrLiAl3N4:Eu 2+ At least two of the fluorescent ceramics.

9. The composite fluorescent sheet according to claim 8, characterized in that: comprising a central first fluorescent ceramic layer arranged in the same plane and a peripheral second fluorescent ceramic layer surrounding the first fluorescent ceramic layer; The central first fluorescent ceramic layer is LuAG:Ce 3+ Fluorescent ceramics or β-sialon fluorescent ceramics; The outer second fluorescent ceramic layer is La3Si6N 11 : Ce 3+ Fluorescent ceramics, including La3Si6N 11 : Ce 3+ The luminescent ceramic layer emits light in the wavelength range of 540 - 560 nm.

10. The method for preparing the composite fluorescent sheet according to claim 1, characterized in that: The preparation process is as follows: Step (1), preparing a core rod of a central fluorescent sheet material blank; Step (2), preparing a second fluorescent sheet slurry surrounding the central fluorescent sheet material; Step (3), applying the slurry prepared in step (2) to the surface of the core rod obtained in step (1) to obtain a composite fluorescent sheet green body material with a double-layer structure; Step (4), curing; Step (5), continue to prepare the slurry of the subsequent fluorescent sheet material, apply it to the surface of the core rod structure obtained by curing in the previous step, and cure it until the slurry coating and curing of the last fluorescent sheet material are completed; Step (6), slicing the obtained composite fluorescent sheet along a direction perpendicular to the radial direction to obtain a sheet-like composite fluorescent sheet.

11. Use of the composite fluorescent sheet according to any one of claims 1 to 8 as a wavelength conversion medium in the field of lighting.

12. An optical color wheel, characterized in that: The composite fluorescent sheet comprises the composite fluorescent sheet as described in any one of claims 1 to 8.

13. A projection device, characterized in that: The optical color wheel comprises a laser light source and the optical color wheel as claimed in claim 12, wherein the optical color wheel generates excitation light under the excitation of the laser light generated by the laser light source.

14. Application of the composite fluorescent sheet according to any one of claims 1 to 8 as a wavelength conversion medium in the field of backlight display.

15. A backlight display device, comprising a backlight display light source and a wavelength conversion element, characterized in that: The wavelength conversion element comprises the composite fluorescent sheet according to any one of claims 1 to 8.

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