Laser white light device for laser display and illumination and preparation method thereof

Abstract

The invention belongs to the technical field of laser diode illumination and display, and particularly relates to a laser white light device for laser display and illumination and a preparation method thereof. Comprising a laser emission module and a fluorescence conversion module. The fluorescence conversion module comprises a pixelated transparent substrate, a green fluorescent powder unit and a red fluorescent powder unit; groove array structures which are arranged in a staggered mode are distributed on the upper side and the lower side of the pixelated transparent substrate respectively. The green fluorescent powder unit is arranged in the lower side groove array structure, and the red fluorescent powder unit is arranged in the upper side groove array structure; the laser emitting module emits laser from the lower portion of the pixelated transparent substrate to the upper portion, and the green fluorescent powder unit and the red fluorescent powder unit are excited to emit green light and red light respectively and then are fused to form white light. According to the invention, the heat dissipation performance of the fluorescence conversion module is improved, the reabsorption between red and green fluorescent powder is weakened, the luminous efficiency is improved, and a white light LD device with high brightness and high color rendering can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser diode lighting and display, and in particular relates to a laser white light device for laser display and lighting and a preparation method thereof. Background Art

[0002] Blue LEDs suffer from efficiency droop, significantly limiting the application of white light-emitting devices in high-power, high-brightness solid-state lighting and displays. Laser lighting is considered the next generation of high-brightness semiconductor light sources for automotive headlights, projection displays, medical endoscopes, and some specialty lighting applications. Laser-excited phosphor technology generates white light from a blue laser diode (LD) via remote excitation of a transmissive or reflective phosphor converter.

[0003] Fluorescent glass is the mainstream inorganic fluorescent conversion composite material for fluorescent converters. However, due to the low thermal conductivity of the glass matrix, fluorescent glass has difficulty maintaining good heat dissipation under high-power laser excitation. Therefore, it is usually combined with a high thermal conductivity substrate to form a fluorescent converter, which can effectively improve the heat dissipation performance. At present, the color rendering index of white light sources used in laser displays is relatively high. One way is to use a fluorescent converter with multiple phosphors to achieve high-color rendering white light. However, when using two or more phosphors with different emitting wavelengths to achieve a high-color rendering white light lighting solution, the luminous efficiency of the fluorescent converter will decrease. This phenomenon is due to the combined effect of multiple complex factors, among which the reabsorption effect between phosphors is particularly prominent. For example, the emission band of the green phosphor overlaps with the absorption band of the red phosphor. The emitted green light will be absorbed by the red phosphor, and the luminous efficiency will decrease. Therefore, how to design a high-brightness and high-color rendering white light LD device is still a technical problem that needs to be overcome urgently. Summary of the Invention

[0004] The purpose of the present invention is to provide a laser white light device for laser display and lighting and a preparation method thereof, aiming to design a white light LD device with high brightness and high color rendering, and to improve the luminous efficiency and heat dissipation by separating the red and green fluorescent units and making close contact with the substrate.

[0005] To achieve the above-mentioned object, the present invention provides a laser white light device for laser display and illumination, comprising a laser emission module and a fluorescence conversion module; the fluorescence conversion module comprises a pixelated transparent substrate, a green phosphor unit and a red phosphor unit; The pixelated transparent substrate is provided with groove array structures on the upper and lower sides, and each groove in the lower groove array structure is located at a position corresponding to the gap between two adjacent grooves on the upper side, forming a staggered arrangement; the green phosphor unit is arranged in the lower groove array structure, and the red phosphor unit is arranged in the upper groove array structure; and they are tightly combined with the pixelated transparent substrate to improve the thermal conductivity. The laser emission module emits laser light from the bottom to the top of the pixelated transparent substrate to excite the green phosphor unit and the red phosphor unit to emit green light and red light respectively, which are then fused to form white light.

[0006] Furthermore, the laser emission module emits blue laser, which is combined with the green light and red light generated by excitation to form white light.

[0007] Furthermore, the groove pitch, length, width and depth of the groove array structure are independently 80-120 μm.

[0008] Furthermore, the thickness of the pixelated transparent substrate is 400-600 μm.

[0009] Furthermore, the width of each groove in the lower groove array structure is equal to the distance between two adjacent grooves on the upper side.

[0010] Furthermore, the pixelated transparent substrate is made of a thermally conductive material with a visible light transmittance greater than 80% and a thermal conductivity close to or greater than 30 W / (m·K), including but not limited to a sapphire transparent substrate and a diamond substrate.

[0011] Furthermore, the green phosphor unit includes green phosphor and glass powder; the red phosphor unit includes red phosphor and glass powder. The green phosphor includes YAGG:Ce 3+ or YAG:Ce 3+ Phosphor; the emission wavelength under blue light excitation is in the range of 500-600nm.

[0012] The red phosphor includes CaAlSiN3:Eu 2+ or CaAlSrN3:Eu 2+ Phosphor. The emission wavelength under blue light excitation is in the 600-750nm wavelength range.

[0013] Furthermore, the mass fraction of the green phosphor relative to the glass powder is 40%-120%; the mass fraction of the red phosphor relative to the glass powder is 40%-120%.

[0014] The present invention also provides a method for preparing a laser white light device for laser display and illumination as described in any one of the above, comprising the following steps: S1. Constructing groove array structures on the upper and lower sides of a transparent substrate to obtain a pixelated transparent substrate; S2. Prepare a green phosphor slurry containing green phosphor and glass powder, and prepare a red phosphor slurry containing red phosphor and glass powder; S3, applying the red phosphor slurry and the green phosphor slurry to fill the groove array structures on the upper and lower sides of the pixelated transparent substrate respectively, and then sintering to obtain green phosphor units and red phosphor units.

[0015] Furthermore, the green phosphor slurry comprises green phosphor, glass powder, terpineol and ethyl cellulose; the mass fraction of the green phosphor relative to the glass powder is 40%-120%; the mass of the green phosphor and the glass powder together accounts for 15%-30% of the green phosphor slurry; The red phosphor slurry comprises red phosphor, glass powder, terpineol and ethyl cellulose; the mass fraction of the red phosphor relative to the glass powder is 40%-120%; the mass of the red phosphor and the glass powder together accounts for 15%-30% of the red phosphor slurry; The sintering temperature is 500-700° C., and the sintering time is 30-60 minutes.

[0016] Furthermore, the preparation method further includes grinding and polishing the upper and lower sides of the pixelated transparent substrate after sintering; ensuring that the height of the green phosphor unit and the red phosphor unit is consistent with the depth of the groove; The groove array structure is constructed by laser processing.

[0017] The present invention also provides an application of the laser white light device for laser display and illumination as described in any one of the above items, wherein the laser white light device for laser display and illumination is used in the field of illumination or display.

[0018] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology: 1. The laser white light device for laser display and lighting provided by the present invention processes pixelated grooves on both sides of the transparent substrate to prepare a double-sided groove array structure. Green fluorescent units and red fluorescent units are respectively arranged at the grooves on both sides. The fluorescent units are tightly fitted with the bottom and side walls of the grooves, and the heat generated can be transmitted from multiple directions. Compared with the traditional fluorescent conversion module (fluorescent glass film + flat substrate), the pixelated groove structure further improves the heat dissipation performance of the fluorescent converter, avoids the problem of luminous saturation, and effectively improves the thermal stability of the white light LD device.

[0019] 2. The present invention uses green and red phosphors to prepare a dual-color fluorescence conversion module, achieving white light with high color rendering. On this basis, red and green fluorescent light-emitting units are respectively arranged in grooves on both sides of the base of the fluorescence conversion module. The corresponding spatial position relationship of the staggered arrangement avoids direct contact between the red and green fluorescent light-emitting units. Most of the green light emitted by the green fluorescent light-emitting unit can be emitted from the gaps between the pixels of the red fluorescent light-emitting unit, greatly reducing the probability of green light being absorbed by the red fluorescent light-emitting unit, improving the luminous efficiency of the dual-color fluorescence conversion module, and achieving white light with high color rendering and high brightness.

[0020] 3. The blue laser of the present invention is incident from one side of the green phosphor unit, which improves the excitation efficiency of the green phosphor and can make the obtained white light brighter. In addition, the green phosphor unit has a higher heat-bearing capacity, so incident from close to the green phosphor unit can reduce the impact of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a fluorescence conversion module of a laser white light device for laser display and illumination provided by an embodiment of the present invention.

[0022] Figure 2 Schematic diagram of a pixelated substrate groove array provided in an embodiment of the present invention.

[0023] Figure 3 It is a schematic diagram of the partial structure of the green phosphor unit provided by an embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of the partial structure of the red phosphor unit provided by an embodiment of the present invention.

[0025] Figure 5 This is a process flow chart for preparing a fluorescence conversion module of a laser white light device for laser display and illumination provided by an embodiment of the present invention.

[0026] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-pixelated transparent substrate, 2-green phosphor unit, 3-red phosphor unit, 4-phosphor unit glass base, 5-green phosphor particles, 6-red phosphor particles. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0028] Example 1 A laser white light device for laser display and illumination and a preparation method thereof, comprising a laser emission module and a fluorescence conversion module; the fluorescence conversion module comprising a pixelated transparent substrate 1, a green phosphor unit 2, and a red phosphor unit 3; the laser emission module emits laser light from below the pixelated transparent substrate 1 to above, stimulating the green phosphor unit 2 and the red phosphor unit 3 to emit green light and red light, respectively, and then the emitted light mixes with the stimulated light to form target color light.

[0029] The pixelated transparent substrate 1 has a double-sided groove array structure, arranged at equal intervals. The grooves on the upper and lower sides are arranged in a staggered spatial relationship. The red phosphor units 3 and green phosphor units 2 are respectively disposed in the upper and lower grooves, tightly integrated with the pixelated transparent substrate 1. This arrangement, on the one hand, reduces light reabsorption due to the staggered arrangement of the grooves; on the other hand, each groove has five surfaces in contact with the pixelated transparent substrate 1, significantly improving thermal conductivity. In addition, because the human eye is more sensitive to green light, laser light incident from the side of the green phosphor unit 2 improves the excitation efficiency of the green phosphor, resulting in a brighter white light. Furthermore, the green phosphor unit 2 has a higher heat-resistance capacity, so incident light from a position close to the green phosphor unit 2 can reduce the impact of heat.

[0030] like Figure 1 As shown, the fluorescent conversion module is made of a transparent thermally conductive substrate 1 and a fluorescent glass material. The transparent thermally conductive substrate is laser-processed into a double-sided groove array structure to achieve a corresponding spatial position relationship of the staggered arrangement of the grooves. The green phosphor unit 2 and the red phosphor unit 3 are respectively arranged in the grooves on both sides, and the fluorescent units are tightly fitted with the bottom and side walls of the grooves. First, the pixelated groove structure of the transparent thermally conductive substrate increases the contact area between the fluorescent unit and the substrate, which enables the heat generated by the fluorescent unit during fluorescence conversion to be quickly dissipated from all sides, significantly improving the heat dissipation performance of the fluorescent conversion module and effectively delaying the problem of luminous saturation; secondly, the staggered spatial distribution of the upper and lower grooves not only avoids direct contact between the red and green phosphors, but also designs a good light-emitting path for the green light, which can effectively reduce the probability of reabsorption of the red and green phosphors and improve the luminous efficiency of white light.

[0031] like Figure 2As shown, optionally, the material of the pixelated transparent substrate 1 needs to meet the requirement of visible light transmittance greater than 80%, and must ensure the effective extraction of incident light and outgoing light; the thermal conductivity is close to or greater than 30 W / (m·K), which can dissipate the generated heat in time and reduce heat accumulation. Furthermore, the total thickness of the pixelated transparent substrate 1 is 400-600μm. If the substrate is too thin, the mechanical properties are weak, which is not conducive to the realization of the double-sided groove array structure. If the substrate is too thick, the light absorption is strong, which is not conducive to improving the light extraction efficiency. The groove shape of the pixelated transparent substrate 1 is a cuboid or a cube. In order to ensure that the groove can smoothly accommodate the phosphor particles, the length, width and height dimensions are 80-120μm respectively.

[0032] Optionally, the green phosphor unit 2 and the red phosphor unit 3 are prepared from a fluorescent glass slurry comprising phosphor, glass powder, and an organic solvent. Furthermore, the glass powder has a glass transition temperature below 800°C, and the phosphor is either green or red, with the amount of the phosphor being 40% to 120% of the weight of the glass powder.

[0033] like Figure 3 、 4 As shown, the phosphor is used to convert fluorescence into the specific wavelength band required to generate white light. After high-temperature sintering, the glass powder becomes the glass base material between the phosphor particles and also serves as the adhesive between the fluorescent glass film and the transparent substrate. The organic solvent serves as a dispersant for the phosphor and glass powder and evaporates after high-temperature sintering. The glass transition temperature of the glass powder is below 700°C, ensuring wettability of the glass substrate at the sintering temperature. The green or red phosphor content is set within a range of 40%-120% of the glass powder weight to ensure that the glass base adequately encapsulates the phosphor particles, improving sintering quality while maintaining the highest possible phosphor concentration for high luminous efficiency.

[0034] Optionally, the green phosphor unit 2 includes at least YAGG:Ce 3+ 、YAG:Ce 3+ A type of phosphor that emits light in the 500-600nm wavelength range when excited by blue light (450nm).

[0035] YAGG:Ce 3+ 、YAG:Ce 3+ The phosphor has good absorption in the blue light wavelength range, and the emission wavelength is in the green light wavelength range of 500-600nm, with a high emission intensity.

[0036] Optionally, the red phosphor unit 3 includes at least CaAlSiN3:Eu 2+ 、CaAlSrN3:Eu 2+A type of phosphor that emits light in the 600-750nm wavelength range when excited by blue light (450nm).

[0037] CaAlSiN3:Eu 2+ 、CaAlSrN3:Eu 2+ The phosphor has good absorption in the blue light wavelength range, and the emission wavelength is in the red light wavelength range of 600-750nm, with a high emission intensity.

[0038] like Figure 1 As shown, the bottom and sides of the green phosphor unit 2 and the red phosphor unit 3 are optionally tightly attached to the pixelated transparent substrate 1, with their height consistent with the depth of the grooves in the pixelated transparent substrate 1. This creates fewer air voids, allowing heat to be transferred both from the bottom and the sides, improving the heat dissipation performance of the phosphor conversion module. The height is consistent with the depth of the grooves in the pixelated transparent substrate 1, ensuring that the top surfaces of the two phosphor units do not rise above the transparent substrate, thereby affecting light output.

[0039] In one embodiment, a transparent substrate material with a visible light transmittance greater than 80% and a thermal conductivity approaching or exceeding 30 W / (m·K) is used in conjunction with fluorescent light-emitting units to form a fluorescence conversion module. A double-sided groove array structure is designed on the transparent substrate, with the fluorescent light-emitting units positioned within the grooves, closely fitting the groove bottom and sidewalls. This effectively achieves multi-channel heat dissipation and improves the heat resistance of the fluorescence conversion module. Furthermore, the embodiments of the present invention utilize red and green phosphors to form two fluorescent light-emitting units, effectively enhancing the color rendering of white light. The staggered spatial arrangement of the red and green fluorescent light-emitting units reduces reabsorption between the two, allowing most of the green light to be successfully extracted rather than being reabsorbed by the red phosphor. This significantly improves the luminous efficiency of the fluorescence conversion module, achieving high-brightness and high-color white light.

[0040] Example 2 like Figure 5 As shown, a method for preparing a laser white light device for laser display and illumination, which is used to prepare the fluorescence conversion module as described in the above example, comprises: S1. Use an ultrasonic cleaning machine to ultrasonically clean the transparent substrate to remove surface impurities; S2. Prepare the pixelated transparent substrate 1: Form an array groove structure on the transparent substrate by laser processing. The groove structure is a rectangular parallelepiped or a cube, and the groove size is in the range of 80-120 μm; S3. Adding terpineol and ethyl cellulose at a fixed mass ratio into a beaker, placing the beaker on a magnetic stirrer for mixing and stirring to prepare an organic solvent; placing the two phosphors and glass powder into a ball mill, mixing them, and mixing them with the organic solvent in a certain proportion to obtain two fluorescent glass mixture slurries; S4. Spin-coat or apply a fluorescent glass mixture slurry on one side of the pixelated transparent substrate and dry it. Spin-coat or apply another fluorescent glass mixture slurry on the other side and dry it. The drying device can be a drying oven or a heating table. The substrate is then placed in a muffle furnace and sintered to obtain the green phosphor unit 2 and the red phosphor unit 3. S5. Grind and polish both sides of the sintered phosphor conversion module to ensure that the heights of the green phosphor unit 2 and the red phosphor unit 3 are consistent with the depth of the groove.

[0041] Optionally, the mass ratio of terpineol to ethyl cellulose is 20:1; the mass fraction of phosphor relative to glass powder is 40%-120%; the mass ratio of mixed powder (phosphor and glass powder) to organic solvent is 1:3; the drying temperature after applying the fluorescent glass mixture slurry is set to 80°C, and the drying time is 30 minutes; the sintering temperature of the green phosphor unit 2 and the red phosphor unit 3 is 500-700°C, and the sintering time is 30-60 minutes.

[0042] By using the method for preparing a laser white light device for laser display and lighting provided in this embodiment, a fluorescence conversion module of a laser white light device for laser display and lighting provided in the embodiment can be prepared, which has the same beneficial effects.

[0043] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A laser white light device for laser display and lighting, characterized in that: It includes a laser emission module and a fluorescence conversion module; the fluorescence conversion module includes a pixelated transparent substrate, a green phosphor unit and a red phosphor unit; The pixelated transparent substrate is provided with groove array structures on the upper and lower sides, respectively, and each groove in the lower groove array structure is located at a position corresponding to the gap between two adjacent grooves on the upper side, forming a staggered arrangement; the green phosphor unit is arranged in the lower groove array structure, and the red phosphor unit is arranged in the upper groove array structure; The laser emission module emits laser light from the bottom to the top of the pixelated transparent substrate to excite the green phosphor unit and the red phosphor unit to emit green light and red light respectively, which are then fused to form white light.

2. The laser white light device for laser display and illumination according to claim 1, characterized in that: The laser emission module emits blue laser, which is fused with the green light and red light generated by excitation to form white light.

3. The laser white light device for laser display and illumination according to claim 1, characterized in that: The groove spacing, length, width and depth of the groove array structure are independently 80-120 μm; And / or, the pixelated transparent substrate has a thickness of 400-600 μm.

4. The laser white light device for laser display and illumination according to claim 1, characterized in that: The width of each groove in the lower groove array structure is equal to the distance between two adjacent grooves on the upper side; And / or, the pixelated transparent substrate is made of a thermally conductive material with a visible light transmittance greater than 80%.

5. The laser white light device for laser display and illumination according to any one of claims 1 to 4, characterized in that: The green phosphor unit includes green phosphor and glass powder; the red phosphor unit includes red phosphor and glass powder; The green phosphor includes YAGG:Ce 3+ or YAG:Ce 3+ phosphors; The red phosphor includes CaAlSiN3:Eu 2+ or CaAlSrN3:Eu 2+ Phosphor.

6. The laser white light device for laser display and illumination according to claim 5, characterized in that: The mass fraction of the green phosphor relative to the glass powder is 40%-120%; the mass fraction of the red phosphor relative to the glass powder is 40%-120%.

7. A method for preparing a laser white light device for laser display and illumination according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Constructing groove array structures on the upper and lower sides of a transparent substrate to obtain a pixelated transparent substrate; S2. Prepare a green phosphor slurry containing green phosphor and glass powder, and prepare a red phosphor slurry containing red phosphor and glass powder; S3, applying the red phosphor slurry and the green phosphor slurry to fill the groove array structures on the upper and lower sides of the pixelated transparent substrate respectively, and then sintering to obtain green phosphor units and red phosphor units.

8. The preparation method according to claim 7, characterized in that The green phosphor slurry comprises green phosphor, glass powder, terpineol and ethyl cellulose; the mass fraction of the green phosphor relative to the glass powder is 40%-120%; the mass of the green phosphor and the glass powder together accounts for 15%-30% of the green phosphor slurry; The red phosphor slurry includes red phosphor, glass powder, terpineol and ethyl cellulose; the mass fraction of the red phosphor relative to the glass powder is 40%-120%; the mass of the red phosphor and the glass powder accounts for 15%-30% of the red phosphor slurry.

9. The preparation method according to claim 7, characterized in that The sintering temperature is 500-700° C., and the sintering time is 30-60 minutes.

10. The preparation method according to claim 7, characterized in that The preparation method further includes grinding and polishing the upper and lower sides of the pixelated transparent substrate after sintering; The groove array structure is constructed by laser processing.

Images