Projection headlamp module

Abstract

The invention relates to the technical field of projection modules, and particularly discloses a projection headlamp module which sequentially comprises a light source module, a fly eye lens, a first relay lens, a first reflective mirror, a second relay lens, a TIR prism, a DMD chip and a projection lens in the light transmission direction. The light source module comprises three light sources, three sets of collimating lens assemblies and three reflectors which are sequentially arranged in the first direction, the three reflectors are arranged at intervals in the second direction, and an included angle is formed between the first direction and the second direction. The DMD chip is used for receiving the light from the TIR prism and converting the light into image light to be emitted back to the TIR prism, and finally the image light is emitted to the projection lens along the projection optical axis of the projection lens through the TIR prism. Wherein the projection optical axis is perpendicular to the plane where the first direction and the second direction are located, so that the arrangement of the lenses is compact, the size of the projection headlamp module is reduced, and the projection headlamp module meets the miniaturization design requirement and is convenient to install.

Description

Technical Field

[0001] This invention relates to the field of projection module technology, specifically to a projection headlight module. Background Technology

[0002] As projection systems are used in more and more fields, the demand for projection lamps is increasing. Currently, projection lamps mainly use projection generation units (PGUs), and the most widely used projection generation unit is DLP technology, which has obvious advantages in terms of light efficiency, clarity, brightness and contrast compared to traditional LCD projection technology.

[0003] However, existing projection lamp modules are relatively large and inconvenient to install because their internal components are arranged in a single direction, which cannot meet the requirements of miniaturization design. Summary of the Invention

[0004] This invention discloses a projection headlight module, the purpose of which is to at least solve one of the technical problems existing in the prior art.

[0005] This invention provides a projection headlight module, comprising: a light source module including three light sources, three collimating lens assemblies, and three reflectors arranged sequentially along a first direction, with the three reflectors spaced apart along a second direction; light emitted by the light sources is directed along the first direction through the collimating lens assemblies to the reflectors, the first direction being perpendicular to the second direction; a compound eye lens disposed along the first direction on the light-emitting side of the light source module; a first relay lens disposed along the first direction on the light-emitting side of the compound eye lens; a first reflector disposed along the first direction on the light-emitting side of the first relay lens, the first reflector including a reflective surface facing the first relay lens, the reflective surface forming an acute angle with the first direction, the reflective surface being used to receive light from the first relay lens and deflect the light; and a second relay lens disposed facing the reflective surface. The device is used to receive light reflected from the reflective surface; a TIR prism includes a first light-incident surface, a first light-exiting surface, a second light-exiting surface, and a total reflection surface. The first light-incident surface is disposed on the light-exiting side of the second relay lens, and the total reflection surface is located on the side of the first light-incident surface away from the second relay lens. The first light-exiting surface and the second light-exiting surface are arranged parallel to each other, and both the first light-incident surface and the total reflection surface are arranged at an angle to the first light-exiting surface and the second light-exiting surface; a DMD chip is disposed facing the first light-exiting surface and is used to receive light from the first light-exiting surface and convert the light into image light and project it back to the first light-exiting surface; a projection lens is disposed facing the second light-exiting surface and has a projection optical axis that is perpendicular to the plane formed by the first direction and the second direction. The projection lens is used to receive image light emitted from the second light-exiting surface.

[0006] In some embodiments of the present invention, along the second direction, the three light sources are arranged in sequence as a blue light source, a green light source and a red light source, and the corresponding three reflectors are arranged in sequence as a blue light reflector, a green light dichroic mirror and a red light dichroic mirror, wherein the red light dichroic mirror is close to the compound eye lens.

[0007] In some embodiments of the present invention, the collimating lens assembly includes a first collimating lens and a second collimating lens arranged along the first direction, the first collimating lens being close to the light source, and the combined focal length of the first collimating lens and the second collimating lens being 6.3 mm to 10.6 mm.

[0008] In some embodiments of the present invention, the first collimating lens is a glass spherical lens with a refractive index Nd between 1.72 and 1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5 mm to 9.8 mm; the second collimating lens is a glass spherical lens with a refractive index Nd between 1.9 and 2.0, a dispersion coefficient Vd greater than 20, and a focal length of 19.2 mm to 19.4 mm.

[0009] In some embodiments of the present invention, both the green dichroic mirror and the red dichroic mirror are set at a 45° angle to the first direction.

[0010] In some embodiments of the present invention, the compound eye lens includes a first surface facing the red dichroic mirror and a second surface facing away from the first surface, the distance between the center point of the red dichroic mirror and the center point of the first surface in the first direction is 13mm to 16mm; and both the first surface and the second surface are provided with microlens arrays, the sagitta of the microlens arrays being 0.1mm to 0.2mm.

[0011] In some embodiments of the present invention, the first relay lens is a glass spherical lens with a refractive index Nd of 1.5 to 1.6, a dispersion coefficient Vd greater than 60, and a focal length of 80 mm to 85 mm; the second relay lens is a glass spherical lens with a refractive index Nd of 1.5 to 1.6, a dispersion coefficient Vd greater than 60, and a focal length of 40.58 mm to 43.58 mm; wherein the distance between the center point of the first relay lens and the center point of the second surface in the first direction is greater than 1.5 mm.

[0012] In some embodiments of the present invention, the angle between the reflective surface and the first direction is 45°, and the distance between the center point of the reflective surface and the center point of the first relay lens in the first direction is greater than 15mm.

[0013] In some embodiments of the present invention, the TIR prism is made of glass with a refractive index Nd of 1.5 to 1.6 and a dispersion coefficient Vd greater than 60, and the angle between the total reflection surface and the plane containing the first direction and the second direction is 30° to 35°.

[0014] In some embodiments of the present invention, the total length of the projection lens is 78mm to 82mm, and the effective focal length of the projection lens is 48mm to 53mm. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the projection headlight module provided by the present invention;

[0016] Figure 2 for Figure 1 The rear view of the projection headlight module in the opposite direction to the first direction;

[0017] Figure 3 for Figure 1 A top view of the projection headlight module along the projection optical axis. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The projection headlight module provided in the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0022] In this embodiment, as Figures 1 to 3As shown in the figure, this embodiment of the invention proposes a projection lamp module, which includes, sequentially along the light transmission path, a light source module 1, a compound eye lens 2, a first relay lens 3, a first reflector 4, a second relay lens 5, a TIR prism 6, a DMD chip 7, and a projection lens 8. The light source module 1 generates and outputs light. The compound eye lens 2 receives the light from the light source module 1 and homogenizes it. The first relay lens 3 receives the light from the compound eye lens 2 and further homogenizes and shapes it. The first reflector 4 receives the light from the first relay lens 3 and redirects it towards the second relay lens 5. The second relay lens 5 receives the light from the first reflector 4 and further homogenizes and shapes it. The TIR prism 6 receives the light from the second relay lens 5 and redirects it towards the DMD chip 7. The DMD chip 7 receives the light from the TIR prism 6 and converts it into image light carrying image information, which is then projected back to the TIR prism 6. The image light is finally transmitted to the projection lens 8 through the TIR prism 6. The projection lens 8 performs projection magnification on the image light, thus completing the projection imaging of the projection lamp module.

[0023] Specifically, such as Figure 1 and Figure 3 As shown, the light source module 1 includes three light sources 11, three collimating lens assemblies 12, and three reflectors 13 arranged sequentially along a first direction X. The three reflectors 13 are spaced apart along a second direction Y. The light emitted by the light source 11 travels along the first direction X, passes through the collimating lens assembly 12, and is reflected by the reflector 13 before exiting the light source module 1 along the first direction X. The first direction X is perpendicular to the second direction Y. Each light source 11 corresponds to one collimating lens assembly 12 and one reflector 13. The light emitted by the light source 11 travels along the first direction X, passes through the collimating lens assembly 12, and is reflected by the reflector 13 before exiting the light source module 1. That is, a single light source 11, a single collimating lens assembly 12, and a single reflector 13 are arranged along the first direction X, while the three light sources 11 are spaced apart along the second direction Y, the three collimating lens assemblies 12 are spaced apart along the second direction Y, and the three reflectors 13 are also spaced apart along the second direction Y.

[0024] In one embodiment, along the second direction Y, three light sources 11 are arranged sequentially as a blue light source 111, a green light source 112, and a red light source 113, and the corresponding three reflectors 13 are arranged sequentially as a blue light reflector 131, a green light dichroic mirror 132, and a red light dichroic mirror 133. That is, the reflector 13 corresponding to the blue light source 111 is a blue light reflector 131, the reflector 13 corresponding to the green light source 112 is a green light dichroic mirror 132, and the reflector 13 corresponding to the red light source 113 is a red light dichroic mirror 133. The red light dichroic mirror 133 is closer to the compound eye lens 2, meaning the red light source 113 is closest to the compound eye lens 2. The blue light reflector 131, the green light dichroic mirror 132, and the red light dichroic mirror 133 work together to redirect and integrate the blue, green, and red light rays. The light source module 1 is designed to consist of a blue light source 111, a green light source 112, and a red light source 113, so that the light source module 1 can project light of more colors and improve the color saturation of the DLP projection module.

[0025] It should be noted that the blue light reflector 131 is used to reflect blue light rays incident on its front side. The green light dichroic mirror 132 is used to reflect green light rays incident on its front side and allow blue light rays incident on its back side to pass through, thus converging the blue and green light rays. The red light dichroic mirror 133 is used to transmit red light rays incident on its front side along the first direction X and reflect blue and green light rays incident on its back side along the first direction X, thus converging and integrating the blue, green, and red light rays. That is, the blue light reflector 131 is a total internal reflection reflector, while the green light dichroic mirror 132 and the red light dichroic mirror 133 are selective reflection reflectors.

[0026] Furthermore, the compound eye lens 2 is positioned along the first direction X on the light-emitting side of the light source module 1, the first relay lens 3 is positioned along the first direction X on the light-emitting side of the compound eye lens 2, and the first reflector 4 is positioned along the first direction X on the light-emitting side of the first relay lens 3. That is, the light emitted from the light source module 1 passes sequentially through the compound eye lens 2 and the first relay lens 3 along the first direction X, and then illuminates the first reflector 4. Figure 3 As shown, the first reflector 4 includes a reflective surface 41 facing the first relay lens 3, and the reflective surface 41 forms an acute angle with the first direction X. The reflective surface 41 is used to receive light from the first relay lens 3 and redirect the light, thereby redirecting the light transmitted along the first direction X. Please refer again. Figure 1 and Figure 2The second relay lens 5 is positioned facing the reflective surface 41 to receive light reflected from it. A TIR prism 6 is positioned on the light-emitting side of the second relay lens 5 to receive light from it and redirect it towards the DMD chip 7. The DMD chip 7 receives light from the TIR prism 6, converts it into image light, and projects it back to the TIR prism 6. Finally, the TIR prism 6 directs the image light along the projection optical axis o of the projection lens 8 towards the projection lens 8. The projection optical axis o is perpendicular to the plane formed by the first direction X and the second direction Y, meaning the projection optical axis o of the projection lens 8 is perpendicular to the plane where the light source module 1 is located. This arrangement of the projection lens 8 and the light source module 1 is compact, reducing the size of the projection lamp module and enabling it to meet miniaturization design requirements for easy installation.

[0027] Specifically, such as Figure 2 As shown, the TIR prism 6 is an optical element that uses total internal reflection technology to control the direction of light. The TIR prism 6 includes a first light-incident surface 61, a first light-exiting surface 62, a second light-exiting surface 63, and a total internal reflection surface 64. The first light-incident surface 61 is located on the light-exiting side of the second relay lens 5. The total internal reflection surface 64 is located on the side of the first light-incident surface 61 away from the second relay lens 5. The first light-exiting surface 62 and the second light-exiting surface 63 are arranged parallel to each other, and both the first light-incident surface 61 and the total internal reflection surface 64 are arranged at an angle to the first light-exiting surface 62 and the second light-exiting surface 63. Light enters the TIR prism 6 from the first light-incident surface 61, is reflected by the total internal reflection surface 64, and exits the TIR prism 6 from the first light-exiting surface 62. The DMD chip 7 converts the light into image light, which then re-enters the TIR prism 6 through the first light-exiting surface 62. The image light then passes through the total internal reflection surface 64 and exits the TIR prism 6 from the second light-exiting surface 63. Furthermore, the first light-incident surface 61 is located on the light-outceasing side of the second relay lens 5, and the DMD chip 7 is positioned opposite the first light-outceasing surface 62 to receive light from the first light-outceasing surface 62; the projection lens 8 is positioned opposite the second light-outceasing surface 63 and is used to receive image light emitted from the second light-outceasing surface 63.

[0028] For ease of understanding, the following detailed explanation is provided in conjunction with the light transmission path. Light rays exiting the second relay lens 5 pass through the first incident surface 61 and enter the TIR prism 6. After being redirected inside the TIR prism 6, they exit through the first exiting surface 62 and enter the DMD chip 7. The DMD chip 7 converts the light into image light carrying image information and reflects it back towards the first exiting surface 62. The image light then re-enters the TIR prism 6 through the first exiting surface 62, passes through the second exiting surface 63, and exits the TIR prism 6 along the projection optical axis o of the projection lens 8, ultimately reaching the projection lens 8. The first and second exiting surfaces 62 redirect the image light transmission, ensuring that the image light can be transmitted to the projection lens 8.

[0029] In some embodiments, such as Figure 1 As shown, the collimating lens assembly 12 includes a first collimating lens 121 and a second collimating lens 122 arranged along the first direction X. The first collimating lens 121 is close to the light source 11, and the combined focal length of the first collimating lens 121 and the second collimating lens 122 is 6.3mm to 10.6mm. Preferably, the first collimating lens 121 is a glass spherical lens with a refractive index Nd between 1.72 and 1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5mm to 9.8mm, ensuring that the first collimating lens 121 has a high light-converging ability and can converge more light from the light source 11. The second collimating lens 122 is a glass spherical lens with a refractive index Nd of 1.9 to 2.0, a dispersion coefficient Vd greater than 20, and a focal length of 19.2 mm to 19.4 mm. This ensures that the second collimating lens 122 has a strong light-gathering ability and that the light can be completely irradiated onto the reflector 13. At the same time, using two collimating lenses can reduce the overall cost of the collimating lens assembly 12 and reduce the processing difficulty of the collimating lens assembly 12.

[0030] In some embodiments, the green dichroic mirror 132 and the red dichroic mirror 133 are both placed at a 45° angle to the first direction X, ensuring that the green dichroic mirror 132 and the red dichroic mirror 133 can reflect part of the light from the collimating lens assembly 12 and transmit it along the second direction Y. At the same time, the distance between the green dichroic mirror 132 and the red dichroic mirror 133 in the second direction Y is shortened, thereby shortening the propagation path distance of the light, that is, shortening the distance between the light source module 1 and the compound eye lens 2, and meeting the miniaturization design requirements.

[0031] In some embodiments, a microlens array is disposed on the surface of the compound eye lens 2, that is, multiple nanopillars are disposed on the surface of the compound eye lens 2, and the surface shape of the microlens array is spherical. The compound eye lens 2 mainly segments the received light, that is, it segments the light spot formed by the light, which is equivalent to dividing a large-aperture light spot into several small-aperture light spots, ultimately improving the uniformity of the light.

[0032] Furthermore, such as Figure 3As shown, the compound eye lens 2 includes a first surface 21 facing the red dichroic mirror 133 and a second surface 22 facing away from the first surface 21. Both the first surface 21 and the second surface 22 are provided with microlens arrays. The sagittal of the microlens arrays is 0.1mm to 0.2mm, ensuring that the compound eye lens 2 meets miniaturization requirements while maintaining excellent optical performance. Furthermore, the distance between the center point of the red dichroic mirror 133 and the center point of the first surface 21 in the first direction X is 13mm to 16mm. By controlling the distance between the compound eye lens 2 and the red dichroic mirror 133, the positions of the compound eye lens 2 and the light source module 1 are rationally arranged to meet the miniaturization design requirements. It should be noted that the aforementioned center point refers to the geometric center point of the structure.

[0033] In some embodiments, the first relay lens 3 is a glass spherical lens with a refractive index Nd of 1.5–1.6, a dispersion coefficient Vd greater than 60, and a focal length of 80 mm–85 mm. The second relay lens 5 is also a glass spherical lens with a refractive index Nd of 1.5–1.6, a dispersion coefficient Vd greater than 60, and a focal length of 40.58 mm–43.58 mm. The use of glass spherical lenses for both the first and second relay lenses ensures that they can homogenize and shape the light, improving the projection imaging quality of the projection headlight module.

[0034] In one embodiment, the distance between the center point of the first relay lens 3 and the center point of the second surface 22 of the compound eye lens 2 in the first direction X is greater than 1.5 mm, ensuring that the first relay lens 3 can fully receive the light from the compound eye lens 2, and controlling the distance between the first relay lens 3 and the compound eye lens 2 to meet the miniaturization design requirements.

[0035] In one embodiment, the angle between the reflective surface 41 of the first reflector 4 and the first relay lens 3 is 45°, and the distance between the center point of the reflective surface 41 and the center point of the first relay lens 3 in the first direction X is greater than 15mm, ensuring that the first reflector 4 can fully receive the light from the first relay lens 3, and limiting the distance between the first relay lens 3 and the first reflector 4 to meet the miniaturization design requirements.

[0036] In some embodiments, the TIR prism 6 is made of glass with a refractive index Nd of 1.5 to 1.6 and a dispersion coefficient Vd greater than 60, ensuring that light entering the TIR prism 6 undergoes total internal reflection within it, thus improving light reflection efficiency and reducing stray light. Preferably, as shown... Figure 2As shown, the angle α between the total internal reflection surface 64 of the TIR prism 6 and the plane containing the first direction X and the second direction Y is 30° to 35°, ensuring that the total internal reflection surface 64 of the TIR prism 6 can perform total internal reflection of light. It can be understood that the first light-emitting surface 62 and the second light-emitting surface 63 of the TIR prism 6 are parallel to the plane containing the first direction X and the second direction Y, which facilitates determining the installation posture of the TIR prism 6 and thus controlling the orientation of the total internal reflection surface 64 of the TIR prism 6.

[0037] In some embodiments, the total length of the projection lens 8 is 78mm to 82mm, and the effective focal length of the projection lens 8 is 48mm to 53mm, which meets the requirements of miniaturization design and ensures the quality of the projected image.

[0038] Preferably, the projection lens 8 consists of five spherical glass lenses, with the diameter of the first lens less than 35mm, the diameter of the fifth lens less than 30mm, and the entrance diameter of the projection lens 8 being 27mm to 29mm, meeting the requirements of miniaturization design. Furthermore, the aperture value F of the projection lens 8 is 1.6 to 2.0 to ensure the image sharpness of the projection lens 8. Also, the ratio of the long side to the short side of the projected image of the projection lens 8 is 2:1, ensuring that the image projected by the projection lens 8 is clearly visible.

[0039] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. A projection headlight module, characterized in that, include: The light source module includes three light sources, three collimating lens assemblies, and three reflectors arranged sequentially along a first direction, and the three reflectors are spaced apart along a second direction. The light emitted by the light sources passes through the collimating lens assemblies along the first direction and is directed to the reflectors. The first direction is perpendicular to the second direction. A compound eye lens is disposed on the light-emitting side of the light source module along the first direction; A first relay lens is disposed on the light-emitting side of the compound eye lens along the first direction; A first reflector is disposed on the light-emitting side of the first relay lens along the first direction. The first reflector includes a reflective surface facing the first relay lens, and the angle between the reflective surface and the first direction is an acute angle. The reflective surface is used to receive light from the first relay lens and redirect the light. A second relay lens is disposed facing the reflective surface and is used to receive light reflected from the reflective surface; A TIR prism includes a first light-incident surface, a first light-exit surface, a second light-exit surface, and a total reflection surface. The first light-incident surface is disposed on the light-exit side of the second relay lens. The total reflection surface is located on the side of the first light-incident surface away from the second relay lens. The first light-exit surface and the second light-exit surface are arranged in parallel, and both the first light-incident surface and the total reflection surface are arranged at an angle to the first light-exit surface and the second light-exit surface. The DMD chip is positioned facing the first light-emitting surface and is used to receive light from the first light-emitting surface and convert the light into image light that is then reflected back to the first light-emitting surface. A projection lens is positioned directly opposite the second light-emitting surface. The projection lens has a projection optical axis that is perpendicular to the plane formed by the first direction and the second direction. The projection lens is used to receive image light emitted from the second light-emitting surface.

2. The projection headlight module according to claim 1, characterized in that, Along the second direction, the three light sources are arranged in sequence as a blue light source, a green light source, and a red light source, and the corresponding three reflectors are arranged in sequence as a blue light reflector, a green light dichroic mirror, and a red light dichroic mirror, wherein the red light dichroic mirror is close to the compound eye lens.

3. The projection headlight module according to claim 2, characterized in that, The collimating lens assembly includes a first collimating lens and a second collimating lens arranged along the first direction. The first collimating lens is close to the light source, and the combined focal length of the first collimating lens and the second collimating lens is 6.3 mm to 10.6 mm.

4. The projection headlight module according to claim 2, characterized in that, The first collimating lens is a glass spherical lens with a refractive index Nd between 1.72 and 1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5 mm to 9.8 mm. The second collimating lens is a glass spherical lens with a refractive index Nd of 1.9 to 2.0, a dispersion coefficient Vd greater than 20, and a focal length of 19.2 mm to 19.4 mm.

5. The projection headlight module according to claim 4, characterized in that, Both the green dichroic mirror and the red dichroic mirror are set at a 45° angle to the first direction.

6. The projection headlight module according to claim 2, characterized in that, The compound eye lens includes a first surface facing the red dichroic mirror and a second surface facing away from the first surface. The distance between the center point of the red dichroic mirror and the center point of the first surface in the first direction is 13mm to 16mm. Furthermore, both the first surface and the second surface are provided with microlens arrays, and the sagittal height of the microlens arrays is 0.1mm to 0.2mm.

7. The projection headlight module according to claim 6, characterized in that, The first relay lens is a glass spherical lens with a refractive index Nd of 1.5 to 1.6, a dispersion coefficient Vd greater than 60, and a focal length of 80 mm to 85 mm. The second relay lens is a glass spherical lens with a refractive index Nd of 1.5 to 1.6, a dispersion coefficient Vd greater than 60, and a focal length of 40.58 mm to 43.58 mm. The distance between the center point of the first relay lens and the center point of the second surface in the first direction is greater than 1.5 mm.

8. The projection headlight module according to claim 7, characterized in that, Furthermore, the angle between the reflective surface and the first direction is 45°, and the distance between the center point of the reflective surface and the center point of the first relay lens in the first direction is greater than 15mm.

9. The projection headlight module according to claim 1, characterized in that, The TIR prism is made of glass with a refractive index Nd of 1.5 to 1.6 and a dispersion coefficient Vd greater than 60. The angle between the total reflection surface and the plane containing the first direction and the second direction is 30° to 35°.

10. The projection headlight module according to claim 1, characterized in that, The total length of the projection lens is 78mm to 82mm, and the effective focal length of the projection lens is 48mm to 53mm.

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