Wavelength conversion module and projection device

Abstract

The invention provides a wavelength conversion module and a projection device. The wavelength conversion module comprises a substrate, a wavelength conversion layer and a diffuse reflection layer. The wavelength conversion layer is disposed on the substrate, and the diffuse reflection layer is disposed between the substrate and the wavelength conversion layer. The diffuse reflection layer comprises a plurality of first diffuse reflection particles and a plurality of second diffuse reflection particles, the volume of each second diffuse reflection particle is 0.3%-7% of the average volume of the first diffuse reflection particles, and the whiteness of the second diffuse reflection particles is larger than or equal to that of the first diffuse reflection particles. The wavelength conversion module and the projection device have good light efficiency, good heat dissipation effect and good reliability.

Description

Technical Field

[0001] The invention relates to an optical module and a display device, and in particular to a wavelength conversion module and a projection device. Background Art

[0002] The existing phosphor wheel for projection device includes a substrate, a diffuse reflection layer and a phosphor layer, wherein the diffuse reflection layer is formed on the substrate, and the phosphor layer is formed on the diffuse reflection layer. After being excited by the excitation light, the phosphor layer emits fluorescence of the corresponding wavelength, and the diffuse reflection layer is used to reflect the fluorescence, and the material of the commonly used diffuse reflection particles is white particles such as aluminum oxide, silicon dioxide or titanium dioxide.

[0003] Since the current diffuse reflection particles all use a particle size close to the wavelength of visible light (such as 400 to 700 nanometers), whether a single diffuse reflection particle or multiple diffuse reflection particles are used, similar particle sizes are used. Therefore, during solidification or sintering, it is easy to cause cracks in the diffuse reflection layer due to shrinkage, thereby affecting the reliability and reflection uniformity of the diffuse reflection layer.

[0004] In addition, the diffuse reflection particles of the diffuse reflection layer are often made of materials with a whiteness greater than 80 and a high refractive index, such as aluminum oxide, silicon dioxide, titanium dioxide, tin dioxide, zinc oxide, zirconium dioxide and other materials. When the excitation light excites the phosphor layer, light energy and heat energy are generated. The diffuse reflection layer reflects the light energy to the light collection system, and the heat energy is dissipated from the surface or conducted by the diffuse reflection layer to the substrate for heat dissipation. Therefore, the diffuse reflection particles require a higher thermal conductivity coefficient, among which aluminum oxide and zinc oxide have higher thermal conductivity coefficients and have good thermal conductivity. However, compared with the two, zinc oxide is prone to aging under high temperature and high humidity conditions, while aluminum oxide has the characteristics of high hardness, high stability, high heat resistance, low expansion coefficient, and high corrosion resistance. Therefore, the industry generally uses aluminum oxide as a diffuse reflection material.

[0005] However, the greater the difference in refractive index between diffuse reflective particles and air oxygen, the higher the reflectivity. The refractive index of aluminum oxide is about 1.76. Compared with oxides with a refractive index greater than 2 such as titanium dioxide, tin dioxide, zinc oxide, and zirconium dioxide, the refractive index of aluminum oxide is lower. Therefore, using aluminum oxide as a diffuse reflective material has the disadvantage of low reflectivity.

[0006] The "background technology" section is only used to help understand the content of the present invention. Therefore, the content disclosed in the "background technology" section may contain some prior art that is not known to those skilled in the art. The content disclosed in the "background technology" section does not mean that the content or the problem to be solved by one or more embodiments of the present invention has been known or recognized by those skilled in the art before the application of the present invention. Summary of the invention

[0007] The invention provides a wavelength conversion module, which has good light efficiency, good heat dissipation effect and good reliability.

[0008] The invention provides a projection device, which has good light efficiency, good heat dissipation effect and good reliability.

[0009] Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

[0010] To achieve one or part or all of the above purposes or other purposes, one embodiment of the present invention provides a wavelength conversion module, which includes a substrate, a wavelength conversion layer and a diffuse reflection layer. The wavelength conversion layer is disposed on the substrate, and the diffuse reflection layer is disposed between the substrate and the wavelength conversion layer. The diffuse reflection layer includes a plurality of first diffuse reflection particles and a plurality of second diffuse reflection particles, wherein the volume of each of the second diffuse reflection particles is 0.3% to 7% of the average volume of the first diffuse reflection particles, and the whiteness of the second diffuse reflection particles is greater than or equal to the whiteness of the first diffuse reflection particles.

[0011] To achieve one or part or all of the above purposes or other purposes, one embodiment of the present invention provides a projection device, which includes an illumination module, a light valve and a projection lens. The illumination module is used to provide an illumination beam, and includes a light source and the above-mentioned wavelength conversion module, wherein the light source is used to emit a laser beam, and the wavelength conversion module is configured on the transmission path of the laser beam. The wavelength conversion layer is used to convert the laser beam into a wavelength conversion beam, and the diffuse reflection layer is used to diffusely reflect the wavelength conversion beam. The illumination beam includes at least one of the wavelength conversion beam and the laser beam. The light valve is configured on the transmission path of the illumination beam, and is used to convert the illumination beam into an image beam. The projection lens is configured on the transmission path of the image beam.

[0012] Based on the above, the embodiments of the present invention have at least one of the following advantages or effects. In the wavelength conversion module and the projection device of the embodiments of the present invention, two kinds of diffuse reflection particles of different sizes are used, wherein the volume of each of the second diffuse reflection particles is 0.3% to 7% of the average volume of the first diffuse reflection particles, and the whiteness of the second diffuse reflection particles is greater than or equal to the whiteness of the first diffuse reflection particles. Therefore, the second diffuse reflection particles can be filled in the gaps of the first diffuse reflection particles, so that the amount of light diffusely reflected can be increased, thereby effectively improving the reflectivity of the diffuse reflection layer, and thus the contact area between the diffuse reflection particles and the substrate can be increased, thereby increasing the heat dissipation effect and reliability of the diffuse reflection layer. Therefore, the wavelength conversion module and the projection device of the embodiments of the present invention using the above-mentioned diffuse reflection layer can have good light efficiency, good heat dissipation effect and good reliability.

[0013] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. 4 is a front view of a wavelength conversion module according to an embodiment of the present invention.

[0015] Figure 2 for Figure 1 Schematic diagram of the cross-section of the wavelength conversion module along line II.

[0016] Figure 3A and Figure 3B The arrangement relationship between the first diffuse reflection particles and the second diffuse reflection particles in two embodiments of the present invention is shown.

[0017] Figure 4 FIG. 4 is a schematic diagram of a projection device according to an embodiment of the present invention.

[0018] Figure 5 Based on Figure 4 A schematic diagram of an optical path of a projection device according to an embodiment of the present invention.

[0019] Reference numerals list

[0020] 100: Wavelength conversion module

[0021] 110:Substrate

[0022] 120: wavelength conversion layer

[0023] 122: Green phosphor layer

[0024] 124: Yellow phosphor layer

[0025] 130: light transmission area

[0026] 140: Motor shaft

[0027] 200: Diffuse reflection layer

[0028] 210: First diffuse reflection particle

[0029] 220: Second diffuse reflection particle

[0030] 230: Colloid

[0031] 300: Projection device

[0032] 310: Lighting module

[0033] 312: Illumination beam

[0034] 320: Light valve

[0035] 322: Image Beam

[0036] 330: Projection lens

[0037] 410: Light source

[0038] 412:Laser beam

[0039] 414: Wavelength conversion beam

[0040] 420: Dichroic Mirror

[0041] 430: Light homogenization element

[0042] 440, 450, 460: Reflector

[0043] T1: Thickness. DETAILED DESCRIPTION

[0044] The above and other technical contents, features and effects of the present invention will be clearly presented in the detailed description of a preferred embodiment made with reference to the drawings below. The directional terms (e.g., up, down, left, right, front or back, etc.) mentioned in the following embodiments are only the directions of the reference drawings. Therefore, the directional terms used are used for explanation and are not used to limit the present invention.

[0045] Figure 1 is a front view schematic diagram of a wavelength conversion module according to an embodiment of the present invention, and Figure 2 for Figure 1 The cross-sectional diagram of the wavelength conversion module along line II. Please refer to Figure 1 and Figure 2 The wavelength conversion module 100 of this embodiment includes a substrate 110, a wavelength conversion layer 120 and a diffuse reflection layer 200. The wavelength conversion layer 120 is disposed on the substrate 110, and the diffuse reflection layer 200 is disposed between the substrate 110 and the wavelength conversion layer 120. In this embodiment, the wavelength conversion layer 120 is a phosphor layer, and the wavelength conversion layer 120 is, for example, C-shaped or O-shaped and is disposed around the central axis of the substrate 110. For example, Figure 1 As shown, the wavelength conversion layer 120 may include a green phosphor layer 122 and a yellow phosphor layer 124. However, in other embodiments, the wavelength conversion layer 120 may also include a red phosphor layer or a combination of phosphor layers of other colors.

[0046] The diffuse reflection layer 200 includes a plurality of first diffuse reflection particles 210 and a plurality of second diffuse reflection particles 220, wherein the volume of each of the second diffuse reflection particles 220 is 0.3% to 7% of the average volume of the first diffuse reflection particles 210. In other words, the size of each second diffuse reflection particle 220 is smaller than the size of each first diffuse reflection particle 210. In addition, the whiteness of the second diffuse reflection particles 220 is greater than or equal to the whiteness of the first diffuse reflection particles 210.

[0047] In the wavelength conversion module 100 of the present embodiment, two kinds of diffuse reflection particles (i.e., first diffuse reflection particles 210 and second diffuse reflection particles 220) of different sizes are used, wherein the volume of each of the second diffuse reflection particles 220 is 0.3% to 7% of the average volume of the first diffuse reflection particles 210, and the whiteness of the second diffuse reflection particles 220 is greater than or equal to the whiteness of the first diffuse reflection particles 210. Therefore, the second diffuse reflection particles 220 can be filled in the gaps generated by the first diffuse reflection particles 210, so that the amount of light diffusely reflected can be increased, thereby effectively improving the reflectivity of the diffuse reflection layer 200, and thus the contact area between the diffuse reflection particles (e.g., the first diffuse reflection particles 210 and the second diffuse reflection particles 220) and the substrate 110 can be increased, thereby increasing the heat dissipation effect and reliability of the diffuse reflection layer 200. Therefore, the wavelength conversion module 100 using the diffuse reflection layer 200 of the present embodiment can have good light efficiency, good heat dissipation effect and good reliability. In this embodiment, after the second diffuse reflective particles 220 are used to fill the gaps created by the first diffuse reflective particles 210 , the contact surface area between the diffuse reflective particles and the substrate 110 increases by 3% to 13% compared to when there are only the first diffuse reflective particles 210 .

[0048] In the present embodiment, since the second diffuse reflective particles 220 are used to fill the gaps generated by the first diffuse reflective particles 210, the total volume of the diffuse reflective particles increases compared to when there are only the first diffuse reflective particles 210, so that the reflectivity (e.g., reflectivity of visible light) of the diffuse reflective layer 200 can be increased by 1 to 2%. In addition, in the present embodiment, since the second diffuse reflective particles 220 are used to fill the gaps generated by the first diffuse reflective particles 210, they can provide a supporting effect, so the diffuse reflective layer 200 can suppress shrinkage during curing or sintering, so that the probability of edge warping, falling off or cracking of the diffuse reflective layer 200 during the curing or sintering process can be reduced, so as to maintain the uniformity and flatness of the diffuse reflective layer 200, thereby improving the reflection uniformity of the diffuse reflective layer 200 and increasing the reliability of the diffuse reflective layer 200.

[0049] In the present embodiment, the diameter of each second diffuse reflection particle 220 is 15% to 42% of the average diameter of the first diffuse reflection particles 210. In one embodiment, the first diffuse reflection particles 210 and the second diffuse reflection particles 220 may be spherical. In addition, in the present embodiment, the diffuse reflection layer 200 further includes a colloid 230, which at least partially covers the first diffuse reflection particles 210 and the second diffuse reflection particles 220 and fills the gaps generated by the first diffuse reflection particles 210 and / or the second diffuse reflection particles 220. In one embodiment, the volume of the colloid 230 accounts for 25 to 45 vol% of the total volume of the diffuse reflection layer 200, where "vol%" is a volume percentage. In addition, in one embodiment, the total volume of the first diffuse reflection particles 210 accounts for 50 to 60 vol% of the total volume of the diffuse reflection layer 230, and the total volume of the second diffuse reflection particles 220 accounts for 5 to 15 vol% of the total volume of the diffuse reflection layer 230.

[0050] In this embodiment, the second diffuse reflection particles 220 and the first diffuse reflection particles 210 are mixed in the diffuse reflection layer 200, for example, uniformly mixed in the diffuse reflection layer 200. In this embodiment, the second diffuse reflection particles 220 are located in the gaps between the first diffuse reflection particles 210. Specifically, at least a portion of the second diffuse reflection particles 220 is located in the gaps between two or more first diffuse reflection particles in contact with each other among the first diffuse reflection particles 210. Figure 3A As shown, in one embodiment, the second diffuse reflective particles 220 are located in the gaps between four first diffuse reflective particles 210 that are in contact with each other. Figure 3B As shown, in one embodiment, the second diffuse reflective particles 220 are located in the gaps between three first diffuse reflective particles 210 that are in contact with each other. Figure 2 FIG. 2 schematically illustrates an example in which the first diffuse reflective particles 210 are stacked in two layers, but the present invention is not limited thereto. In fact, the first diffuse reflective particles 210 may be stacked in more than two layers or in only one layer.

[0051] In this embodiment, the ratio of the refractive index of the second diffuse reflective particles 220 to the refractive index of the first diffuse reflective particles 210 is greater than 1.1. Therefore, after the second diffuse reflective particles 220 are filled in the gaps created by the first diffuse reflective particles 210, the average refractive index of the diffuse reflective layer 200 can be increased, thereby increasing the reflectivity of the diffuse reflective layer 200 by 1 to 2% compared to when only the first diffuse reflective particles 210 are present.

[0052] The material of the first diffuse reflection particles 210 is, for example, aluminum oxide (Al 2 O 3), but the present invention is not limited thereto. In addition, the material of the second diffuse reflection particles 220 is, for example, titanium dioxide (TiO 2 ), tin dioxide (SnO 2 )、zinc oxide (zinc oxide, ZnO), zirconium dioxide (zirconiumdioxide, ZrO 2 ) or a combination thereof, but the present invention is not limited thereto. In this embodiment, the colloid 230 is one or a combination of organic glue, inorganic glue, glass, siloxane, sol-gel, but the present invention is not limited thereto.

[0053] In this embodiment, without reducing the overall thermal conductivity of the diffuse reflection layer 200, the volume of each of the second diffuse reflection particles 220 is 0.3% to 7% of the average volume of the first diffuse reflection particles 210, so that the second diffuse reflection particles 220 can easily fill the gaps between the first diffuse reflection particles 210, thereby increasing the total volume and total surface area of ​​the diffuse reflection particles, so that the light beam entering the diffuse reflection layer 200 can more easily irradiate the diffuse reflection particles to improve the reflectivity. If the volume of each of the second diffuse reflection particles 220 exceeds the upper limit of the above range, it is not easy to fill the gaps, and even a larger gap will be formed, thereby reducing the thermal conductivity; on the other hand, if the volume of each of the second diffuse reflection particles 220 does not reach the lower limit of the above range, although it can fill the gaps, the small volume also means that it is not easy to be irradiated by the light beam, and the reflection effect is limited.

[0054] It is worth noting that the same diffuse reflective particles may also have a certain particle size distribution. Therefore, those skilled in the art may understand the above-mentioned 0.3% to 7% condition and may infer it by measuring the average volume of multiple particles. The measurement method may include measuring with an electron microscope (such as a scanning electron microscope). The electron microscope can capture the surface or cross-section of the diffuse reflective particles to obtain their particle size, and obtain the volume of the diffuse reflective particles by particle size calculation. In addition, the condition that the total volume of these second diffuse reflective particles 220 accounts for 5 to 15 vol% of the total volume of the diffuse reflective layer 230 can also be measured through an electron microscope, or the colloid 230 can be removed, for example, after being removed with a solvent, the diffuse reflective particles of different particle sizes are separated by centrifugation or sieving, and the total volume of the particles is measured. When the total volume proportion of the second diffuse reflection particles 220 exceeds the upper limit of the above range, the second diffuse reflection particles 220 have already filled all the gaps, and the excess second diffuse reflection particles 220 cannot further improve the reflectivity, thus resulting in waste; on the other hand, if the total volume proportion of the second diffuse reflection particles 220 does not reach the lower limit of the above range, some of the gaps will not be filled with the second diffuse reflection particles 220, resulting in limited improvement in the reflection effect.

[0055] In this embodiment, the thickness T1 of the diffuse reflection layer 200 falls within a range of 0.05 mm to 0.20 mm, wherein the thickness T1 is a height in a direction perpendicular to the extension direction of the substrate 110 , such as a vertical spacing distance between the substrate 110 and the wavelength conversion layer 120 .

[0056] Figure 4 FIG. 4 is a schematic diagram of a projection device according to an embodiment of the present invention. Figure 5 Based on Figure 4 Please refer to the optical path diagram of the projection device of an embodiment of the present invention. Figure 1 , Figure 2 , Figure 4 and Figure 5 The projection device 300 of this embodiment includes an illumination module 310, a light valve 320 and a projection lens 330. The illumination module 310 is used to provide an illumination beam 312. The illumination module 310 includes a light source 410 and the wavelength conversion module 100. The light source 410 is used to emit a laser beam 412. In this embodiment, the light source 410 is, for example, at least one laser emitter or at least one laser diode. For example, the light source 410 may be a blue laser diode, and the laser beam 412 is a blue laser beam. The wavelength conversion module 100 is disposed on the transmission path of the laser beam 412. The wavelength conversion layer 120 is used to be excited by the laser beam 412 to convert a wavelength conversion beam 414, and the diffuse reflection layer 200 is used to diffusely reflect the wavelength conversion beam 414. The illumination beam 312 includes at least one of the wavelength conversion beam 414 and the laser beam 412.

[0057] Specifically, the laser beam 412 is irradiated on the wavelength conversion layer 120 (eg Figure 1After the green phosphor layer 122 and the yellow phosphor layer 124 are formed, a wavelength conversion light beam 414 is excited, wherein the wavelength conversion light beam 414 is, for example, one of green light, yellow light and red light or a combination thereof. In the present embodiment, the wavelength conversion module 100 further includes a light-transmitting area 130, and a light-transmitting glass or a light-through opening may be provided at the light-transmitting area 130. In addition, the wavelength conversion module 100 further includes a motor (not shown), and the rotating shaft 140 of the motor is connected to the substrate 110 to drive the substrate 110 to rotate. When the substrate 110 is driven by the rotating shaft 140 of the motor and rotates around the rotating shaft 140 as the central axis, the wavelength conversion layer 120 and the light-transmitting area 130 are sequentially cut into the transmission path of the laser beam 412. A dichroic mirror 420 may be provided between the light source 410 and the wavelength conversion module 100, and the dichroic mirror 420 is suitable for allowing the laser beam 412 to penetrate and be transmitted to the wavelength conversion module 100. When the wavelength conversion layer 120 cuts into the transmission path of the laser beam 412, the wavelength conversion layer 120 converts the laser beam 412 into a wavelength conversion beam 414, and the dichroic mirror 420 is suitable for reflecting the wavelength conversion beam to the homogenizing element 430, wherein the homogenizing element 430 is, for example, a light integrating rod or a lens array.

[0058] When the light-transmitting area 130 of the wavelength conversion module 100 cuts into the transmission path of the laser beam 412, the laser beam 412 penetrates the light-transmitting area 130, and is then sequentially reflected back to the dichroic mirror 420 by the reflectors 440, 450, and 460, and then penetrates the dichroic mirror 420 and is transmitted to the light-homogenizing element 430. The light-homogenizing element 430 homogenizes the laser beam 412 and the wavelength conversion beam 414, thereby forming the illumination beam 312. In another embodiment, the wavelength conversion module 100 may also be provided with a reflective area to replace the light-transmitting area 130, and the laser beam 412 reflected by the reflective area may still be transmitted to the light-homogenizing element 430 through other reflectors or dichroic mirrors.

[0059] The light valve 320 is disposed on the transmission path of the illumination light beam 312 and is used to convert the illumination light beam 312 into an image light beam 322. In the present embodiment, the light valve 320 is, for example, a digital micro-mirror device (DMD), a liquid crystal-on-silicon panel (LCOS panel), a transmissive liquid crystal panel or other spatial light modulators. The projection lens 330 is disposed on the transmission path of the image light beam 322 to project the image light beam 322 onto a screen or a projection surface to form an image. Since the wavelength conversion module 100 adopts the design of the diffuse reflection layer 200, the projection device 300 of the present embodiment can have good light efficiency, good image quality, good heat dissipation effect and good reliability.

[0060] In summary, the embodiments of the present invention have at least one of the following advantages or effects. In the wavelength conversion module and the projection device of the embodiments of the present invention, two kinds of diffuse reflection particles of different sizes are used, wherein the volume of each of the second diffuse reflection particles is 0.3% to 7% of the average volume of the first diffuse reflection particles, and the whiteness of the second diffuse reflection particles is greater than or equal to the whiteness of the first diffuse reflection particles. Therefore, the second diffuse reflection particles can be filled in the gaps generated by the first diffuse reflection particles, so that the amount of light diffusely reflected can be increased, thereby effectively improving the reflectivity of the diffuse reflection layer, and thus the contact area between the diffuse reflection particles and the substrate can be increased, thereby increasing the heat dissipation effect and reliability of the diffuse reflection layer. Therefore, the wavelength conversion module and the projection device of the embodiments of the present invention using the above-mentioned diffuse reflection layer can have good light efficiency, good heat dissipation effect and good reliability.

[0061] The above description is only a preferred embodiment of the present invention, and it cannot be used to limit the scope of the implementation of the present invention. That is, all simple equivalent changes and modifications made in accordance with the claims of the present invention and the specification of the present invention are still within the scope of the patent of the present invention. In addition, any embodiment or claim of the present invention is not required to achieve all the purposes, advantages or features disclosed in the present invention. In addition, the abstract of the specification and the name of the invention are only used to assist in the retrieval of patent documents, and are not used to limit the scope of rights of the present invention. In addition, the terms "first", "second", etc. mentioned in this specification or claims are only used to name the name of the element or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A wavelength conversion module, characterized in that: The wavelength conversion module comprises a substrate, a wavelength conversion layer and a diffuse reflection layer, wherein: The wavelength conversion layer is configured on the substrate; The diffuse reflection layer is disposed between the substrate and the wavelength conversion layer, and includes a plurality of first diffuse reflection particles and a plurality of second diffuse reflection particles, wherein the volume of each of the plurality of second diffuse reflection particles is 0.3% to 7% of the average volume of the plurality of first diffuse reflection particles, and the whiteness of the plurality of second diffuse reflection particles is greater than or equal to the whiteness of the plurality of first diffuse reflection particles.

2. The wavelength conversion module according to claim 1, characterized in that: The total volume of the plurality of first diffuse reflective particles accounts for 50 to 60 vol% of the total volume of the diffuse reflective layer, and the total volume of the plurality of second diffuse reflective particles accounts for 5 to 15 vol% of the total volume of the diffuse reflective layer.

3. The wavelength conversion module according to claim 1, characterized in that: A ratio of a refractive index of the plurality of second diffuse reflective particles to a refractive index of the plurality of first diffuse reflective particles is greater than 1.

1.

4. The wavelength conversion module according to claim 1, characterized in that: The material of the plurality of first diffuse reflection particles is aluminum oxide.

5. The wavelength conversion module according to claim 1, characterized in that: The material of the plurality of second diffuse reflection particles is one of titanium dioxide, tin dioxide, zinc oxide, and zirconium dioxide, or a combination thereof.

6. The wavelength conversion module according to claim 1, characterized in that: The diffuse reflection layer further includes a colloid, and the volume of the colloid accounts for 25 to 45 vol% of the total volume of the diffuse reflection layer.

7. The wavelength conversion module according to claim 6, characterized in that: The colloid is one of organic glue, inorganic glue, glass, siloxane, sol-gel or a combination thereof.

8. The wavelength conversion module according to claim 1, characterized in that: The thickness of the diffuse reflection layer is in the range of 0.05 mm to 0.20 mm.

9. The wavelength conversion module according to claim 1, characterized in that: The plurality of second diffuse reflection particles and the plurality of first diffuse reflection particles are mixed in the diffuse reflection layer.

10. The wavelength conversion module according to claim 1, characterized in that: The plurality of second diffuse reflection particles are located in gaps between the plurality of first diffuse reflection particles.

11. The wavelength conversion module according to claim 1, characterized in that: At least a portion of the plurality of second diffuse reflection particles is located in a gap between two first diffuse reflection particles that are in contact with each other among the plurality of first diffuse reflection particles.

12. The wavelength conversion module according to claim 1, characterized in that: A diameter of each of the second diffusely reflective particles is 15% to 42% of an average diameter of the plurality of first diffusely reflective particles.

13. A projection device, characterized in that: The projection device comprises an illumination module, a light valve and a projection lens, wherein: The lighting module is used to provide an illumination beam. The lighting module includes a light source and a wavelength conversion module, wherein the light source is used to emit a laser beam. The wavelength conversion module is arranged on a transmission path of the laser beam and includes a substrate, a wavelength conversion layer, and a diffuse reflection layer, wherein: The wavelength conversion layer is disposed on the substrate and is used to convert the laser beam into a wavelength conversion beam; The diffuse reflection layer is disposed between the substrate and the wavelength conversion layer and is used for diffusely reflecting the wavelength conversion light beam. The diffuse reflection layer includes a plurality of first diffuse reflection particles and a plurality of second diffuse reflection particles, wherein the volume of each of the plurality of second diffuse reflection particles is 0.3% to 7% of the average volume of the plurality of first diffuse reflection particles, and the whiteness of the plurality of second diffuse reflection particles is greater than or equal to the whiteness of the plurality of first diffuse reflection particles, wherein the illumination light beam includes at least one of the wavelength conversion light beam and the laser light beam; the light valve is disposed on the transmission path of the illumination light beam and is used for converting the illumination light beam into an image light beam; The projection lens is arranged on the transmission path of the image light beam.

14. The projection device according to claim 13, characterized in that: The total volume of the plurality of first diffuse reflective particles accounts for 50 to 60 vol% of the total volume of the diffuse reflective layer, and the total volume of the plurality of second diffuse reflective particles accounts for 5 to 15 vol% of the total volume of the diffuse reflective layer.

15. The projection device according to claim 13, characterized in that: A ratio of a refractive index of the plurality of second diffuse reflective particles to a refractive index of the plurality of first diffuse reflective particles is greater than 1.

1.

16. The projection device according to claim 13, characterized in that: The material of the plurality of first diffuse reflection particles is aluminum oxide.

17. The projection device according to claim 13, characterized in that: The material of the plurality of second diffuse reflection particles is one of titanium dioxide, tin dioxide, zinc oxide, and zirconium dioxide, or a combination thereof.

18. The projection device according to claim 13, characterized in that: The diffuse reflection layer further includes a colloid, and the volume of the colloid accounts for 25 to 45 vol% of the total volume of the diffuse reflection layer.

19. The projection device according to claim 18, characterized in that: The colloid is one of organic glue, inorganic glue, glass, siloxane, sol-gel or a combination thereof.

20. The projection device according to claim 13, characterized in that: The thickness of the diffuse reflection layer is in the range of 0.05 mm to 0.20 mm.

21. The projection device according to claim 13, characterized in that: The plurality of second diffuse reflection particles and the plurality of first diffuse reflection particles are mixed in the diffuse reflection layer.

22. The projection device according to claim 13, characterized in that: The plurality of second diffuse reflection particles are located in gaps between the plurality of first diffuse reflection particles.

23. The projection device according to claim 13, characterized in that: At least a portion of the plurality of second diffuse reflection particles is located in a gap between two first diffuse reflection particles that are in contact with each other among the plurality of first diffuse reflection particles.

24. The projection device according to claim 13, characterized in that: A diameter of each of the second diffusely reflective particles is 15% to 42% of an average diameter of the plurality of first diffusely reflective particles.

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