Projection lens, projection device and terminal

Abstract

Embodiments of the present application provide a projection lens, a projection device and a terminal, and belong to the technical field of projection. The projection lens comprises, in order from the image side to the object side, a first lens group, a second lens group, a third lens group and a fourth lens group. The first lens group and the fourth lens group are fixed lens groups, and the first lens group and the fourth lens group both have optical power. The second lens group and the third lens group each comprise at least one lens, and the second lens group and the third lens group both have optical power. The second lens group and the third lens group are movable relative to the fixed lens groups along the optical axis direction of the projection lens, so as to change the projection distance of the projection lens. In this way, the projection distance of the projection lens is adjustable, the projection lens can be applied to multiple scenes with different projection distances, the cost can be reduced, for example, the projection lens can be applied to in-vehicle projection, head-up display and other on-vehicle scenes, and multiple projection lenses applied to vehicles do not need to be designed respectively.

Description

Technical Field

[0001] This application relates to the field of projection technology, and in particular to a projection lens, projection device and terminal. Background Technology

[0002] With the development of intelligent vehicle technology, there are increasingly more scenarios requiring the application of projection lenses in vehicles. For example, cars are equipped with head-up displays (HUDs) and in-vehicle display systems for in-vehicle entertainment, to meet the needs of in-vehicle projection and head-up display scenarios. Both in-vehicle display systems and HUDs include projection lenses and image sources. The image source generates an image beam that forms an image and projects it onto the projection lens. The projection lens can then project the image beam onto the projection screen of the in-vehicle display system or onto a position at a certain distance from the viewer's eyes, achieving in-vehicle projection or head-up display.

[0003] However, the projection distance of the lenses used in head-up displays (HUDs) is large, making them unsuitable for in-vehicle projection scenarios. Similarly, the projection distance of the lenses used in in-vehicle display systems is small, also unsuitable for HUDs. Therefore, existing technologies require designing multiple lenses with different projection distances to meet the needs of various scenarios, resulting in high development costs and expenses. Utility Model Content

[0004] This application provides a projection lens, a projection device, and a terminal. The projection distance of the projection lens is adjustable, which can be applied to multiple scenarios with different projection distances, thereby reducing costs.

[0005] In a first aspect, embodiments of this application provide a projection lens comprising a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the image side to the object side. The first and fourth lens groups are both fixed lens groups, each including at least one lens element, and both have optical power. The first lens group is the lens group closest to the image side, and the fourth lens group is the lens group closest to the object side. The second and third lens groups each include at least one lens element, and both have optical power. Both the second and third lens groups can be moved relative to the fixed lens groups along the optical axis of the projection lens to change the projection distance of the projection lens.

[0006] By moving the second and third lens groups relative to the fixed lens group along the optical axis, the projection distance of the projection lens can be adjusted. This allows the projection distance to meet the needs of multiple scenarios with different projection distances, enabling the projection lens to be applied in various scenarios, such as in-vehicle projection and head-up displays. This eliminates the need to design multiple projection lenses with different projection distances, reducing development costs. Furthermore, during manufacturing, it is unnecessary to prepare multiple projection lenses with different projection distances; only one projection lens as provided in this embodiment is needed, standardizing materials and helping to reduce costs. In addition, by setting the second and third lens groups as movable lens groups that move relative to the fixed lens group, the difficulty of achieving different projection distances can be effectively balanced.

[0007] Based on this, setting the first and fourth lens groups as fixed lens groups allows the total optical length of the projection lens to remain constant, ensuring a fixed size for the projection lens and reducing the difficulty of applying it to various scenarios. Additionally, it also reduces the difficulty of dustproof sealing of the projection lens.

[0008] In some possible implementations, the projection lens also includes an aperture stop, which is positioned in the optical path between the second and third lens groups.

[0009] In this way, the lenses on both sides of the aperture can automatically offset some aberrations, such as distortion and coma, which helps to reduce the number of lenses in the projection lens and improve image quality.

[0010] In some possible implementations, the projection lenses satisfy the relationship: |EFLG2|>|EFLG3|. Here, EFLG2 is the focal length of the second lens group, and EFLG3 is the focal length of the third lens group. With this setup, the focal length of the second lens group is greater than that of the third lens group, so moving either of them has different effects on the projection distance. The second lens group, with its larger focal length, has a smaller impact on the projection distance when moved, allowing for fine-tuning. The third lens group, with its smaller focal length, has a larger impact when moved, allowing for adjustment even with small movements. Furthermore, when the projection lenses are integrated into the projection device, the third lens group is located between the second lens group and the image source of the projection device. Setting the focal length of the third lens group to a smaller focal length increases the adjustable range of the projection distance (the closer to the image source, the more sensitive the changes).

[0011] In some possible implementations, the projection lens satisfies the relationship: 10 < |EFLG2 / EFL| < 80. Here, EFL is the focal length of the projection lens, and EFLG2 is the focal length of the second lens group. This results in a larger focal length for the second lens group, minimizing the impact on the projection distance during movement and allowing for fine-tuning.

[0012] In some possible implementation manners, the projection lens satisfies the relation: 0.8 < |EFLG3 / EFL| < 2.6. Here, EFL is the focal length of the projection lens, and EFLG3 is the focal length of the third lens group. In this way, the focal length of the third lens group is relatively small, and the influence is relatively large when it moves. A small movement can achieve adjustment.

[0013] In some possible implementation manners, the projection lens satisfies the relation: 10 mm < EFL < 25 mm.

[0014] In this way, it is possible to avoid too long or too short focal lengths, and can effectively balance the imaging quality, volume, and cost of the projection lens.

[0015] In some possible implementation manners, the projection lens satisfies the relation: 0 < D1 < 6 mm. Here, D1 is the moving stroke of the second lens group moving along the optical axis direction. With this setting, the adjustable range for fine-tuning the second lens group can be satisfied, and the adjustment accuracy can be improved.

[0016] In some possible implementation manners, the projection lens satisfies the relation: 0 < D2 < 8 mm. Here, D2 is the moving stroke of the third lens group moving along the optical axis direction. With this setting, the change amount of the projection distance of the projection lens can be relatively large, and the difficulty of changing the projection distance of the projection lens can be reduced.

[0017] In some possible implementation manners, both the first lens group and the second lens group have negative optical powers, and both the third lens group and the fourth lens group have positive optical powers.

[0018] In this way, the imaging ability of the projection lens can be improved, and the imaging quality of the projection lens can be improved.

[0019] In some possible implementation manners, the projection lens further includes at least one cemented lens group, and the cemented lens group is formed by cementing at least two adjacent lenses. At least one of the second lens group and the third lens group includes a cemented lens group.

[0020] In this way, because the cemented lens group has the characteristic of aberration correction, setting the cemented lens group in the second lens group and / or the third lens group can improve the imaging quality. In addition, cementing at least two adjacent lenses into a cemented lens group can simplify the assembly process of the projection lens and reduce the cost. Moreover, it helps to reduce the maximum size of the projection lens in the optical axis direction and helps to miniaturize the projection lens.

[0021] In some possible implementation manners, the fourth lens group has a cemented lens group, and / or, the first lens group has a cemented lens group. In this way, the imaging quality can be further improved, and the assembly process of the projection lens can be further simplified and the cost can be reduced.

[0022] In some possible implementations, the first, second, third, and fourth lens groups each contain multiple lenses. This can further enhance the imaging capabilities and image quality of the projection lens.

[0023] In some possible implementations, the second lens group has at least three lenses. And / or, the third lens group has at least three lenses. This can further enhance the imaging capability and image quality of the projection lens.

[0024] In some possible implementations, the first lens group has at least two lenses. This configuration can further enhance the imaging capability and image quality of the projection lens.

[0025] In some possible implementations, the fourth lens group has at least five lenses. This configuration can further enhance the imaging capabilities and image quality of the projection lens.

[0026] In some possible implementations, the number of lenses in the projection lens is greater than or equal to 13 and less than or equal to 16. This configuration can further enhance the imaging capability and image quality of the projection lens.

[0027] In some possible implementations, the second lens group moves in the opposite direction to the third lens group during the process of changing the projection distance of the projection lens. This arrangement further reduces the difficulty of changing the projection distance. Additionally, it allows for a larger travel range for both the second and third lens groups, which helps to increase the range of projection distance variations.

[0028] In some possible implementations, as the projection distance of the projection lens changes from a first distance to a second distance, the second lens group moves along the direction from the first lens group to the fourth lens group, and the third lens group moves along the direction from the fourth lens group to the first lens group. The first distance is greater than the second distance. This arrangement allows the second and third lens groups to have a larger travel range, which helps to increase the range of projection distance variation.

[0029] In some possible implementations, the second lens group moves in the same direction as the third lens group when the projection distance of the projection lens is changed. This arrangement reduces the difficulty of moving the second and third lens groups.

[0030] In some possible implementations, the projection lens includes a first lens barrel, a second lens barrel, and a third lens barrel. The first lens barrel is rotatably fitted onto the second lens barrel, and the first lens barrel is rotatably fitted onto the third lens barrel. The first lens barrel is provided with a first cam groove and a second cam groove. The second and third lens barrels are arranged along the optical axis of the projection lens. The second lens barrel is provided with a first cam pin extending into the first cam groove, and the third lens barrel is provided with a second cam pin extending into the second cam groove. When the first lens barrel rotates about the optical axis of the projection lens, both the second and third lens barrels move along the optical axis. The second lens group is fixedly connected inside the second lens barrel, and the third lens group is fixedly connected inside the third lens barrel. In this way, by rotating the first lens barrel, the second and third lens groups can be moved along the optical axis.

[0031] In some possible implementations, the projection lens further includes a fourth lens barrel, a fifth lens barrel, a first flange, and a second flange. The first flange is fitted onto and threadedly connected to the fourth lens barrel, and the second flange is fitted onto and threadedly connected to the fifth lens barrel. A second lens group is fixedly connected inside the fourth lens barrel, and a third lens group is fixedly connected inside the fifth lens barrel. Thus, by rotating the first and second flanges, the second and third lens groups can be moved along the optical axis.

[0032] Secondly, embodiments of this application also provide a projection device, which includes an image source and a projection lens as described in any of the first aspects. The image source is used to generate an image beam capable of forming an image and to project the image beam onto the projection lens. A fourth lens group of the projection lens is used to receive the image beam generated by the image source.

[0033] In some possible implementations, the image source includes a light source and a modulation device. The modulation device is used to modulate the light emitted by the light source to obtain an image beam that includes image information.

[0034] Thirdly, embodiments of this application also provide a terminal, which includes the projection device as described in the second aspect.

[0035] In some possible implementations, the terminal also includes a processor for sending image data to the image source of the projection device, so that the image source generates an image beam. This allows the terminal to emit an image beam to form an image.

[0036] In some possible implementations, the terminal also includes a processor for controlling the movement of the second and third lens groups along the optical axis of the projection lens. This allows adjustment of the projection distance of the projection lens, thereby determining the position of the image and improving the user experience.

[0037] In some possible implementations, the terminal is a vehicle, which includes a display device, and the display device includes a projection device. This allows for scenarios such as head-up displays and in-vehicle projection to be implemented in vehicles.

[0038] In some possible implementations, there are multiple display devices, including a first display device and a second display device. The projection distance of the projection lens of the first display device is different from that of the projection lens of the second display device. In this way, the projection lenses of the first aspect can be arranged in different positions on the vehicle, resulting in a wide range of applications and reducing the cost of the transportation vehicle.

[0039] In some possible implementations, the terminal also includes a driving device for moving the second and third lens groups of the projection lens along the optical axis of the projection lens. This allows adjustment of the projection distance of the projection lens. Attached Figure Description

[0040] Figure 1 A schematic diagram of the projection device provided in an embodiment of this application;

[0041] Figure 2 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0042] Figure 3 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0043] Figure 4 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0044] Figure 5 for Figure 2 A spherical chromatic aberration diagram of the projection lens in the image;

[0045] Figure 6 for Figure 3 Image scattering curve of the projection lens in the image;

[0046] Figure 7 for Figure 3 The distortion diagram of the projection lens in the image;

[0047] Figure 8 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0048] Figure 9 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0049] Figure 10 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0050] Figure 11 for Figure 8 A spherical chromatic aberration diagram of the projection lens in the image;

[0051] Figure 12 for Figure 8 Image scattering curve of the projection lens in the image;

[0052] Figure 13 for Figure 8 The distortion diagram of the projection lens in the image;

[0053] Figure 14 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0054] Figure 15 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0055] Figure 16 This is another schematic diagram of the projection device provided in the embodiments of this application;

[0056] Figure 17 for Figure 14 A spherical chromatic aberration diagram of the projection lens in the image;

[0057] Figure 18 for Figure 14 Image scattering curve of the projection lens in the image;

[0058] Figure 19 for Figure 14 The distortion diagram of the projection lens in the image.

[0059] Explanation of reference numerals in the attached figures:

[0060] 100. Projection device;

[0061] 200. Projection lens; 210. First lens group; 220. Second lens group; 230. Third lens group; 240. Fourth lens group; 250. Aperture stop;

[0062] 300. Image source; 310. Light source; 320. Modulation device;

[0063] 400. Cover glass;

[0064] G1, First lens; G2, Second lens; G3, Third lens; G4, Fourth lens; G5, Fifth lens; G6, Sixth lens; G7, Seventh lens; G8, Eighth lens; G9, Ninth lens; G10, Tenth lens; G11, Eleventh lens; G12, Twelfth lens; G13, Thirteenth lens; G14, Fourteenth lens; G15, Fifteenth lens; G16, Sixteenth lens. Detailed Implementation

[0065] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0066] To facilitate understanding, the relevant technical terms involved in the embodiments of this application will first be explained and described.

[0067] Effective focal length (EFL), also known as focal length, is a measure of the convergence or divergence of light in an optical system. It refers to the vertical distance from the optical center of a lens or lens group to the focal plane when a scene at infinity is formed into a sharp image on the focal plane.

[0068] The image side is the side where the image is located, with the projection lens as the boundary. The side of the lens facing the image side is the image side of the lens.

[0069] The object side is the side where the modulation device (e.g., DMD) is located, and the side of the lens facing the object side is the object side.

[0070] Optical power is the ability of a lens to refract a parallel beam of light incident from an incident lens.

[0071] Positive focal length means that the lens has a positive focal length and has the effect of converging light.

[0072] Negative power means that the lens has a negative focal length, which has the effect of diverging light.

[0073] Back focal length (BFL) is the distance from the vertex of the last optical surface of the lens to the focal point at the back of the lens.

[0074] The radius of curvature R typically refers to the radius of curvature of a lens in the paraxial region. In optical software, the radius of curvature R usually refers to the R value in the lens data database, with positive and negative values ​​indicating convexity or concavity. For the object side, a positive R value indicates a convex surface, and a negative R value indicates a concave surface. For the image side, a positive R value indicates a concave surface, and a negative R value indicates a convex surface.

[0075] The optical axis is a ray of light that passes perpendicularly through the center of an ideal lens. When rays of light parallel to the optical axis enter a convex lens, the ideal convex lens should have all the rays converging at a single point behind the lens; this point where all the rays converge is called the focal point.

[0076] The travel distance refers to the distance that the movable lens group in the projection lens can move along the optical axis of the projection lens during the process of adjusting the projection distance.

[0077] Field curvature, also known as "image field bending," refers to the phenomenon where, after a planar object passes through a lens system, the image plane formed by focusing all planar object points does not coincide with the ideal image plane, but instead presents a curved image plane.

[0078] Axial chromatic aberration, also known as longitudinal chromatic aberration or positional chromatic aberration, occurs when a beam of light parallel to the optical axis converges at different positions after passing through a projection lens. This aberration is called positional chromatic aberration or axial chromatic aberration. This is because the projection lens images light of different wavelengths at different positions, causing the images of different colors of light to not completely overlap during the final imaging process, resulting in the dispersion of polychromatic light.

[0079] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical system relative to the object itself. Distortion occurs due to aperture aberration; the height of the intersection point between the principal ray from different fields of view and the Gaussian image plane after passing through the optical system is not equal to the ideal image height, and this difference is the distortion. Therefore, distortion only changes the imaging position of an off-axis object point on the ideal plane, causing distortion in the image shape, but it does not affect the image's sharpness.

[0080] The eye box typically refers to the entire area of ​​the display image that the driver's eyes can see. If the driver's eyes are within the eye box, they can see a complete and clear image. If the driver's eyes are outside the eye box, they may see distorted images, incorrect colors, or even no image at all.

[0081] This application provides a projection device that can be integrated into any projection device with projection functionality, such as a projector or projection lamp. This projection device is suitable for indoor projection scenarios, such as home theater projection and cinema projection. Alternatively, it can also be used for outdoor projection scenarios, such as advertising projection and road sign projection.

[0082] Of course, projection devices can also be integrated into head-up displays (HUDs), in-vehicle display systems that enable in-vehicle entertainment, and other projection devices used in automobiles.

[0083] Both the in-vehicle display system and the head-up display include a projection lens and an image source. The image source generates an image beam that forms an image and projects it onto the projection lens. The projection lens can project the image beam onto the projection screen of the in-vehicle display system, achieving in-vehicle projection. Alternatively, the projection lens can project the image beam to a position at a certain distance from the viewer's eyes, achieving head-up display.

[0084] However, the projection distance of the lenses used in head-up displays (HUDs) is large, making them unsuitable for in-vehicle projection scenarios. Similarly, the projection distance of the lenses used in in-vehicle display systems is small, also unsuitable for HUDs. Therefore, current technology requires designing multiple lenses with different projection distances to meet the needs of various scenarios, resulting in high development costs and expenses.

[0085] Figure 1 This is a schematic diagram of a projection device provided in an embodiment of this application.

[0086] Therefore, in the embodiments of this application, see Figure 1 The projection device 100 includes an image source 300 and a projection lens 200. The image source 300 generates an image beam capable of forming an image and projects the image beam onto the projection lens 200. The fourth lens group 240 of the projection lens 200 receives the image beam generated by the image source 300. The projection lens 200 includes a first lens group 210, a second lens group 220, a third lens group 230, and a fourth lens group 240 arranged sequentially from the image side to the object side. Both the first lens group 210 and the fourth lens group 240 are fixed lens groups, each including at least one lens element, and both have optical power. The first lens group 210 is the lens group closest to the image side of the projection lens 200, and the fourth lens group 240 is the lens group closest to the object side of the projection lens 200. Both the second lens group 220 and the third lens group 230 include at least one lens, both have optical power, both are movable lens groups, and both can be aligned along the optical axis of the projection lens 200 (e.g., ...). Figure 1 The projection distance of the projection lens 200 is changed by moving it relative to the fixed lens group in the Z direction.

[0087] The movement of the second mirror group 220 and the third mirror group 230 relative to the fixed mirror group can also be understood as the movement of the second mirror group 220 and the third mirror group 230 relative to the first mirror group 210 along the optical axis, or the movement of the second mirror group 220 and the third mirror group 230 relative to the fourth mirror group 240 along the optical axis.

[0088] "Having optical power" means that the optical power is not zero. In addition, "having optical power" in any one of the lens groups 210, 220, 230 and 240 means that the overall optical power of the lens group is not zero, not the optical power of a single lens in the lens group.

[0089] Among them, the fixed lens group refers to the lens group whose position in the projection lens 200 remains unchanged, or the fixed lens group whose position in the optical axis direction of the projection lens 200 remains unchanged.

[0090] The movable lens group refers to a lens group whose position can change within the projection lens 200, or the movable lens group whose position in the optical axis direction of the projection lens 200 can change.

[0091] In this embodiment, by moving the second lens group 220 and the third lens group 230 relative to the fixed lens group along the optical axis, the projection distance of the projection lens 200 can be adjusted. This allows the projection distance of the projection lens 200 to have multiple different values, thus enabling it to meet the needs of multiple scenarios with different projection distances. The projection lens 200 can be applied in various scenarios, such as in-vehicle projection and head-up displays. This eliminates the need to design multiple projection lenses 200 with different projection distances separately, reducing development costs. Furthermore, since the projection distance of the projection lens 200 is adjustable, during manufacturing, it is unnecessary to prepare multiple projection lenses 200 with different projection distances; only one type of projection lens 200 provided in this embodiment needs to be prepared, standardizing materials and helping to reduce costs.

[0092] Furthermore, by setting the second lens group 220 and the third lens group 230 as movable lens groups that move relative to the fixed lens group, the difficulty of balancing image quality, cost, and projection distance can be effectively balanced. In addition, setting the first lens group 210 and the fourth lens group 240 as fixed lens groups allows the total optical length of the projection lens 200 to remain constant, ensuring a fixed size for the projection lens 200 and reducing the difficulty of applying the projection lens 200 to various scenarios. Moreover, setting the first lens group 210 and the fourth lens group 240 to a fixed precision also reduces the difficulty of dustproof sealing of the projection lens 200.

[0093] It should be noted that by controlling the moving distance of the second lens group 220 and the third lens group 230, the projection lens 200 can have multiple projection states, and the projection distance of any two projection states is different.

[0094] During the movement of the second mirror group 220 and the third mirror group 230 along the optical axis, the distance that the second mirror group 220 moves along the optical axis and the distance that the third mirror group 230 moves along the optical axis may be the same or different.

[0095] It should also be noted that, in addition to having two fixed lens groups, the projection lens 200 may have more than two fixed lens groups in some embodiments, such as three or four. Similarly, the projection lens 200 may have more than two movable lens groups, such as three or four.

[0096] In some possible implementations, the projection lens 200 also includes an aperture stop 250, which is positioned in the optical path between the second lens group 220 and the third lens group 230. In this way, the lenses on both sides of the aperture stop 250 can automatically offset some aberrations, such as distortion and coma, helping to reduce the number of lenses in the projection lens 200 and improve image quality.

[0097] It should be noted that, in addition to being positioned in the optical path between the second lens group 220 and the third lens group 230, the aperture 250 can also be positioned in other locations. For example, the aperture 250 can also be positioned in the optical path between the first lens group 210 and the second lens group 220. Alternatively, in some embodiments, the first lens group 210 can be positioned between the aperture 250 and the second lens group 220.

[0098] In some embodiments, the aperture of the light-transmitting hole of the aperture 250 is a fixed value, that is, the aperture of the light-transmitting hole of the aperture 250 cannot be changed.

[0099] In some embodiments, the aperture 250 may also be a variable aperture, in which case the aperture diameter of the light-transmitting hole of the aperture 250 is variable.

[0100] In some possible implementations, the projection lens 200 satisfies the relationship: |EFLG2|>|EFLG3|. Here, EFLG2 is the focal length of the second lens group 220, and EFLG3 is the focal length of the third lens group 230. With this configuration, the focal length of the second lens group 220 is greater than that of the third lens group 230, so moving either of them has different effects on the projection distance. The second lens group 220, with its larger focal length, has a smaller impact on the projection distance when moved, allowing for fine-tuning. The third lens group 230, with its smaller focal length, has a larger impact when moved, allowing for adjustment with only minor movements. Furthermore, when the projection lens is integrated into the projection device 100, the third lens group 230 is located between the second lens group 220 and the image source 300 of the projection device 100. Setting the focal length of the third lens group 230 to a smaller focal length increases the adjustable range of the projection distance (the closer it is to the image source 300, the more sensitive the change).

[0101] In some possible implementations, the projection lens 200 satisfies the relationship: 10 < |EFLG2 / EFL| < 80. Here, EFL is the focal length of the projection lens 200, and EFLG2 is the focal length of the second lens group 220. This results in a larger focal length for the second lens group 220, minimizing the impact on the projection distance during movement and allowing for fine-tuning.

[0102] For example, the specific ratio of |EFLG2 / EFL| may include, but is not limited to, 11, 14, 15, 19, 20, 35, 45, 50, 66, 70, etc.

[0103] In some possible implementation manners, the projection lens 200 satisfies the relational expression: 0.8 < |EFLG3 / EFL| < 2.6. Wherein, EFLG3 is the focal length of the third lens group 230. In this way, the focal length of the third lens group 230 is relatively small, and the influence is relatively large when it moves, and fine adjustment can be achieved with a slight movement.

[0104] For example, the specific ratio of |EFLG3 / EFL| may include, but is not limited to, 0.9, 0.95, 1, 1.1, 1.5, 1.6, 1.9, 2.0, 2.5, etc.

[0105] In some possible implementation manners, the projection lens 200 satisfies the relational expression: 10 mm < EFL < 25 mm. In this way, it is possible to avoid too long or too short focal lengths, and effectively balance the imaging quality, volume and cost of the projection lens 200.

[0106] For example, the specific value of EFL may include, but is not limited to, 11 mm, 12 mm, 15 mm, 17 mm, 18 mm, 19 mm, 22 mm, 23 mm, etc.

[0107] In some possible implementation manners, the projection lens 200 satisfies the relational expression: 0 < D1 < 6 mm. Wherein, D1 is the moving stroke of the second lens group 220 moving along the optical axis direction. With such a setting, the adjustable range of the second lens group 220 can be satisfied, and the adjustment accuracy can be improved.

[0108] For example, the specific value of D1 may include, but is not limited to, 3 mm, 4 mm, 5 mm, etc.

[0109] In some possible implementation manners, the projection lens 200 satisfies the relational expression: 0 < D2 < 8 mm. Wherein, D2 is the moving stroke of the third lens group 230 moving along the optical axis direction. With such a setting, the change amount of the projection distance of the projection lens 200 can be relatively large, and the difficulty of changing the projection distance of the projection lens 200 can be reduced.

[0110] For example, the specific value of D2 may include, but is not limited to, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, etc.

[0111] In some possible implementation manners, both the first lens group 210 and the second lens group 220 have negative optical powers, and both the third lens group 230 and the fourth lens group 240 have positive optical powers. In this way, the imaging ability of the projection lens 200 can be improved, and the imaging quality of the projection lens 200 can be improved.

[0112] It should be noted that the optical power architecture of the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 can be other architectures besides negative-negative-positive-positive, such as negative-positive-negative-positive.

[0113] It should be noted that, apart from being opposite, the optical powers of the second lens group 220 and the third lens group 230 can be the same in some embodiments, for example, both having negative or positive optical powers.

[0114] In some possible implementations, the projection lens 200 also includes at least one cemented lens assembly, which is formed by cementing together at least two adjacent lenses. At least one of the second lens assembly 220 and the third lens assembly 230 includes a cemented lens assembly; for example, both the second lens assembly 220 and the third lens assembly 230 include a cemented lens assembly.

[0115] Thus, due to the aberration correction characteristics of the cemented lens assembly, incorporating a cemented lens assembly in the second lens group 220 and / or the second lens group 220 can improve image quality. Furthermore, bonding at least two adjacent lenses together with an optical adhesive to form a cemented lens assembly simplifies the assembly process of the projection lens 200 and reduces costs. In addition, it helps to reduce the maximum size of the projection lens 200 along the optical axis, contributing to the miniaturization of the projection lens 200.

[0116] Among them, the cemented lens assembly can also be called cemented lens or cemented lens.

[0117] In some embodiments, two adjacent lenses can be bonded together as a whole using an optical adhesive.

[0118] It should be noted that in a cemented lens assembly, the absolute values ​​of the radii of curvature of the two surfaces on which two adjacent lenses are cemented are equal, ensuring that the two lenses can be cemented together.

[0119] It should be noted that within the same lens group, there can be one or more cemented lens groups. For example, the second lens group 220 may contain one cemented lens group.

[0120] When there are multiple cemented lens groups in the projection lens 200, the number of lenses in the multiple cemented lens groups may be the same or different, or, a part of the multiple cemented lens groups may have the same number of lenses, while another part may have different numbers of lenses.

[0121] It should be noted that when the projection lens 200 is equipped with other movable lens groups besides the second lens group 220 and the third lens group 230, it may also include glued lens groups.

[0122] In some possible implementations, the fourth lens group 240 has a cemented lens group, and / or the first lens group 210 has a cemented lens group. This can further improve image quality and further simplify the assembly process of the projection lens 200, reducing costs.

[0123] It should be noted that when the projection lens 200 is equipped with other fixed lens groups besides the first lens group 210 and the fourth lens group 240, the other fixed lens groups may also include cemented lens groups.

[0124] In some possible implementations, the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 each have multiple lenses. This can further enhance the imaging capability and image quality of the projection lens 200.

[0125] In this system, each of the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 has at least two lenses. Furthermore, the number of lenses in the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 may be the same or different; alternatively, some of the lenses in the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 may have the same number of lenses, while others may have different numbers of lenses.

[0126] In some possible implementations, both the second lens group 220 and the third lens group 230 have at least three lenses. This can further enhance the imaging capability and image quality of the projection lens 200.

[0127] In some possible implementations, the first lens group 210 has at least two lenses. This configuration can further enhance the imaging capability and image quality of the projection lens 200.

[0128] In some possible implementations, the fourth lens group 240 has at least five lenses. This configuration can further enhance the imaging capability and image quality of the projection lens 200.

[0129] In some possible implementations, the number of lenses in the projection lens 200 is greater than or equal to 13 and less than or equal to 16. This configuration can further enhance the imaging capability and image quality of the projection lens 200.

[0130] It should be noted that the number of lenses in the projection lens 200 can be less than 13 or more than 16, in addition to being between 13 and 16.

[0131] In some possible implementations, during the process of changing the projection distance of the projection lens 200, the movement direction of the second lens group 220 is opposite to that of the third lens group 230. This arrangement can further reduce the difficulty of changing the projection distance of the projection lens 200. Additionally, it allows the second lens group 220 and the third lens group 230 to have a larger travel range, which helps to increase the range of projection distance variations.

[0132] In some embodiments, as the projection distance of the projection lens 200 changes from a first distance to a second distance, the second lens group 220 moves along the direction from the first lens group 210 to the fourth lens group 240, and the third lens group 230 moves along the direction from the fourth lens group 240 to the first lens group 210. The first distance is greater than the second distance. This arrangement allows the second lens group 220 and the third lens group 230 to have a larger travel range, which helps to increase the range of projection distance variation.

[0133] Alternatively, in some embodiments, as the projection distance of the projection lens 200 changes from a first distance to a second distance, the second lens group 220 moves along the direction from the fourth lens group 240 to the first lens group 210, and the third lens group 230 moves along the direction from the first lens group 210 to the fourth lens group 240. The first distance is greater than the second distance. This arrangement allows the second lens group 220 and the third lens group 230 to have a larger travel distance, which helps to increase the range of projection distance variation.

[0134] It should be noted that, during the process of changing the projection distance of the projection lens 200, the movement direction of the second lens group 220 and the third lens group 230 can, in some possible implementations, be the same, except that they are opposite. For example, both the second lens group 220 and the third lens group 230 can move along the direction from the fourth lens group 240 to the first lens group 210. This arrangement reduces the difficulty of moving the second lens group 220 and the third lens group 230.

[0135] In some embodiments, when the second lens group 220 and the third lens group 230 have opposite optical powers, they can be controlled to move in the same direction, or they can be controlled to move in different directions.

[0136] When the second lens group 220 and the third lens group 230 have opposite optical powers, the ratio of the focal length of one of them to the focal length of the projection lens 200 is negative, and the ratio of the focal length of the other to the focal length of the projection lens 200 is positive. If they move in the same direction, they will have opposite effects on the projection distance. Therefore, when the second lens group 220 and the third lens group 230 have opposite optical powers, controlling them to move in opposite directions can make them have the same effect on the projection distance, which helps to reduce the difficulty of changing the projection distance.

[0137] In some embodiments, the second lens group 220 and the third lens group 230 both have positive optical power, and the first lens group 210 and the fourth lens group 240 both have negative optical power. The second lens group 220 and the third lens group 230 can be controlled to move in the same direction, or they can be controlled to move in different directions, both of which can affect the projection distance. Specifically, when the second lens group 220 and the third lens group 230 move in the same direction, they have the same effect on the projection distance.

[0138] In some embodiments, the second lens group 220 and the third lens group 230 both have negative optical power, and the first lens group 210 and the fourth lens group 240 both have positive optical power. The second lens group 220 and the third lens group 230 can be controlled to move in the same direction, or they can be controlled to move in different directions, both of which can affect the projection distance. Specifically, when the second lens group 220 and the third lens group 230 move in the same direction, they have the same effect on the projection distance.

[0139] In some possible implementations, the projection lens 200 includes a first lens barrel, a second lens barrel, and a third lens barrel. The first lens barrel is rotatably fitted onto the second lens barrel, and the first lens barrel is rotatably fitted onto the third lens barrel. The first lens barrel is provided with a first cam groove and a second cam groove. The second and third lens barrels are arranged along the optical axis of the projection lens 200. The second lens barrel is provided with a first cam pin extending into the first cam groove, and the third lens barrel is provided with a second cam pin extending into the second cam groove. When the first lens barrel rotates around the optical axis of the projection lens 200, both the second and third lens barrels move along the optical axis. The second lens group 220 is fixedly connected inside the second lens barrel, and the third lens group 230 is fixedly connected inside the third lens barrel. In this way, by rotating the first lens barrel, the second lens group 220 and the third lens group 230 can be moved along the optical axis.

[0140] In some possible implementations, the projection lens 200 further includes a fourth lens barrel, a fifth lens barrel, a first flange, and a second flange. The first flange is fitted onto and threadedly connected to the fourth lens barrel, and the second flange is fitted onto and threadedly connected to the fifth lens barrel. A second lens group 220 is fixedly connected inside the fourth lens barrel, and a third lens group 230 is fixedly connected inside the fifth lens barrel. Thus, by rotating the first and second flanges, the second lens group 220 and the third lens group 230 can be moved along the optical axis.

[0141] In some embodiments, the first flange and the second flange can be rotated by corresponding tooling fixtures, so that the fourth lens barrel and the fifth lens barrel move along the optical axis, thereby moving the second lens group 220 and the third lens group 230 a certain distance, so that the projection distance of the projection lens 200 is a preset distance.

[0142] In some embodiments, the first flange and the second flange can be rotated under the drive of the driving device, so that the fourth lens barrel and the fifth lens barrel move along the optical axis, thereby moving the second lens group 220 and the third lens group 230 a certain distance, so that the projection distance of the projection lens 200 is a preset distance.

[0143] In some possible implementations, during the installation of the projection lens 200 on devices such as HUDs and in-vehicle displays, the first lens or flange of the projection lens 200 can be moved by a corresponding adjustment device, so that the second lens group 220 and the third lens group 230 move along the optical axis, thereby adjusting the projection distance of the projection lens 200 to the projection distance corresponding to the HUD, in-vehicle displays, and other devices, so that the projection lens 200 can be applied to various scenarios with different projection distances.

[0144] In some possible implementations, the projection device 100 may also include a driving device for driving the second lens group 220 and the third lens group 230 of the projection lens 200 to move along the optical axis of the projection lens 200, so as to adjust the projection distance of the projection lens 200.

[0145] For example, after integrating the projection lens 200 into devices such as HUDs and in-vehicle displays, the second lens group 220 and the third lens group 230 can be moved along the optical axis by a drive device, so that the projection distance of the projection lens 200 is adjusted to the projection distance corresponding to the HUD, in-vehicle displays and other devices, and the projection lens 200 can be applied to various scenarios with different projection distances.

[0146] In some scenarios, during the use of the projection device 100, the second lens group 220 and the third lens group 230 are moved by the driving device to adjust the projection distance of the projection lens 200 and improve the user experience.

[0147] In some possible implementations, the driving device may include a first motor and a first transmission component. The motor shaft of the first motor is connected to the first lens barrel via the first transmission component. The first motor drives the first lens barrel to rotate via the first transmission component, thereby causing the second and third lens barrels to move along the optical axis.

[0148] The specific structure of the first transmission component is not limited here. For example, the first transmission component may include a first gear and a second gear, with the first gear fixedly connected to the motor shaft of the first motor and the second gear fixedly connected to the first mirror barrel.

[0149] In some possible implementations, the image source 300 includes a light source 310 and a modulation device 320. The modulation device 320 is used to modulate the light emitted by the light source 310 to obtain an image beam including image information.

[0150] See also the following for some possible implementations. Figure 1 The image source 300 includes a light source 310 and a modulation device 320. The modulation device 320 is used to modulate the light emitted by the light source 310 to obtain an image beam including image information.

[0151] The modulation device 320 may include, but is not limited to, liquid crystal display (LCD), liquid crystal on silicon (LCOS), digital micromirror device (DMD), and thin film transistor (TFT).

[0152] In some possible implementations, the projection device 100 also includes a polarizing device (not shown in the figure), which is disposed between the light-emitting side of the image source 300 and the light-incoming side of the projection lens 200. Since the polarizing device has a filtering function, it can filter out certain polarized light beams, thereby further improving the image quality.

[0153] The polarization device may include, but is not limited to, polarizing filters, PBS prisms, etc. Furthermore, the number of polarization devices can be one or more; for example, the number of polarization devices can be two or three.

[0154] In some possible implementations, such as Figure 1 As shown, the projection device 100 also includes a cover glass 400 (CG), which is disposed between the light-emitting side of the image source 300 and the light-incoming side of the projection lens 200. The cover glass 400 can protect the image source 300, prevent damage to the image source 300, and improve the reliability of the projection device 100.

[0155] The number of cover glass 400 can be one or more, for example, two or three. When there are multiple cover glass 400, the multiple cover glass 400 can be disposed between the light-inlet side of the projection lens 200 and the light-outlet side of the image source 300.

[0156] It should be noted that the projection device 100 may have both a cover glass 400 and a polarizing device. In this case, both the cover glass 400 and the polarizing device are disposed between the light-inlet side of the projection lens 200 and the light-outlet side of the image source 300. Alternatively, the projection device 100 may have only one of the cover glass 400 and the polarizing device.

[0157] In some possible implementations, the projection device 100 also includes a diffusion element (not shown) for diffusing the image beam emitted from the projection lens 200. By increasing the diffusion angle of the image beam through the diffusion element, the eye box can be expanded.

[0158] In some embodiments, the diffusion element may be disposed at the imaging surface of the projection lens 200. Of course, in addition to being disposed at the imaging surface of the projection lens 200, the diffusion element may also be disposed at other locations, such as on the windshield.

[0159] In some embodiments, the diffusion element is a reflective diffusion element, which is used to diffuse the image beam and reflect the diffused image beam.

[0160] In some embodiments, the diffusion element is a transmissive diffusion element, which is used to diffuse the image beam and transmit the diffused image beam.

[0161] In some embodiments, the diffusion element may be a diffusion screen, which may also be called a diffusion sheet or diffusion plate.

[0162] The specific structure of the diffusion element is not limited here. For example, the surface of the diffusion element may be provided with a microstructure array, which includes multiple microstructures arranged in an array to achieve the diffusion of light.

[0163] In some embodiments, the diffusion element can be a holographic diffusion element, which is a holographic optical element (HOE) made using holographic technology. The diffusion function of the HOE is achieved through a holographic exposure process, mainly utilizing the photochemical reaction of photosensitive materials to record interference patterns and form specific micro-nano structures, thereby controlling the scattering and diffraction of incident light. In this way, the holographic diffusion element can produce a diffusion effect on imaging light at a specific incident angle while maintaining high transmittance for ambient light, allowing the driver to see the image while clearly viewing the real environment.

[0164] In some embodiments, the diffusion element may also be a particle diffusion element generated by the particle diffusion function. A particle diffusion element is an optical thin film that achieves light homogenization by incorporating scattering particles.

[0165] In some possible implementations, the projection device 100 may also include a reflective element (not shown) for reflecting the image beam projected by the projection lens 200. By reflecting the image beam projected by the projection lens 200 through the reflective element, the outgoing light path of the projection lens 200 can be folded, helping to reduce the size of the projection device 100 and making it more suitable for confined environments such as vehicle interiors. Furthermore, the reflection of the image beam by the reflective element can generate multiple reflected lights with different optical paths, achieving multi-focal surface display.

[0166] The reflective element may include at least one reflector, which may include, but is not limited to, a curved reflector, a flat reflector, etc.

[0167] The structure and performance of the projection device 100 provided in this application will be described below with reference to specific embodiments.

[0168] Figure 2 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 3 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 4 This is another structural schematic diagram of the projection device 100 provided in an embodiment of this application. It should be noted that... Figure 2 , Figure 3 and Figure 4 The projection lens 200 is in the long projection distance state, medium projection distance state and short projection distance state respectively.

[0169] See Figure 2 The projection device 100 includes a projection lens 200, an image source 300, and a cover glass 400. The image source 300 includes a modulator 320 and a light source 310 (not shown in the figure). The modulator 320 modulates the light emitted by the light source 310 to obtain image light including image information. The cover glass 400 is disposed between the light-emitting side of the modulator 320 and the light-incoming side of the projection lens 200.

[0170] See also Figure 2 The projection lens 200 includes a first lens group 210, a second lens group 220, an aperture 250, a third lens group 230, and a fourth lens group 240 arranged sequentially from the image side to the object side. The first lens group 210 and the fourth lens group 240 are both fixed lens groups, while the second lens group 220 and the third lens group 230 are both movable lens groups. The second lens group 220 and the third lens group 230 can move relative to the fixed lens group along the optical axis of the projection lens 200 to change the projection distance of the projection lens 200.

[0171] The projection lens 200 can include multiple projection distance states; for example, the projection lens 200 can include a long projection distance state (such as...). Figure 2As shown), the projection distance status (e.g.) Figure 3 (as shown) and short projection distance state (such as) Figure 4 As shown, by controlling the second lens group 220 and the third lens group 230 to move along the optical axis, the projection lens 200 can switch between any two states among the long projection distance state, the medium projection distance state, and the short projection distance state.

[0172] Combination Figures 2 to 4 It can be seen that during the process of changing the projection distance of the projection lens 200 from the first distance to the second distance, the second lens group 220 moves along the direction from the first lens group 210 to the fourth lens group 240, and the third lens group 230 moves along the direction from the fourth lens group 240 to the first lens group 210. The first distance is greater than the second distance, and the first and second distances correspond to the projection distances of the projection lens 200 under two different projection distance states. For example, the first distance could be the projection distance of the projection lens 200 in a long projection distance state, and the second distance could be the projection distance of the projection lens 200 in a medium projection distance state.

[0173] The first lens group 210 has negative optical power, and its focal length EFG1 = -97.81 mm. The first lens group 210 may include a first lens G1, a second lens G2, and a third lens G3 arranged from the image side to the object side. The first lens G1 is the lens closest to the image side in the first lens group 210, and the second lens G2 and the third lens G3 constitute a cemented lens group.

[0174] The second lens group 220 has negative optical power and a focal length EFG2 = -409.55mm. The second lens group 220 may include a fourth lens G4, a fifth lens G5, and a sixth lens G6 arranged from the image side to the object side. The fourth lens G4 is the lens in the second lens group 220 that is closest to the first lens group 210. The fifth lens G5 and the sixth lens G6 form a cemented lens group.

[0175] The third lens group 230 has positive power and a focal length EFG2 = 32.94 mm. The third lens group 230 may include a seventh lens G7, an eighth lens G8, a ninth lens G9, and a tenth lens G10 arranged from the image side to the object side. The seventh lens G7 is the lens closest to the aperture stop 250 in the third lens group 230. The eighth lens G8, the ninth lens G9, and the tenth lens G10 constitute a cemented lens group.

[0176] The fourth lens group 240 has positive power and a focal length EFG2 = 98.973 mm. The fourth lens group 240 may include an eleventh lens G11, a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, and a fifteenth lens G15 arranged from the image side to the object side. The eleventh lens G11 is the lens in the fourth lens group 240 that is closest to the third lens group 230. The twelfth lens G12 and the thirteenth lens G13 form a cemented lens group.

[0177] The focal length EFL of projection lens 200 is 20.5mm, and the back focal length BFL of projection lens 200 is 19.55mm.

[0178] Table 1 shows Figure 2 The optical parameters of each optical element of the projection device 100 shown.

[0179] Face number Surface type R(mm) TH(mm) Nd Vd OBJ spherical Infinity T0 S1 spherical 71.55 1.25 1.804 39.64 (S2 spherical 15.61 1.87 S3 spherical 468.92 1.44 1.618 63.35 S4 spherical 145.32 3.19 1.808 22.69 S5 spherical 20.91 1.13 S6 spherical 13.24 T6 (S7 spherical 12.76 6.66 1.8216( 24.09 S8 spherical 15.12 0.15 ( S9 spherical 26.10 2.49( 1.594 60.48 S10 spherical 89.85 1.20 1.805 25.46 S11 spherical 26.02 T11 Stop spherical Infinity 0.88 S12 spherical 110.36 4.75 1.692 54.58 S13 spherical 19.74 2.61 S14 spherical 15.34 1.20 1.755 27.54 S15 spherical 37.39 5.88 1.806 40.94 S16 spherical 22.06 6.73 1.464 65.77 S17 spherical 21.37 T17 S18 spherical 91.50 4.80( 1.593 68.35 (S19 spherical 19.92 0.34 ( S20 spherical 18.09 1.20 1.854 25.15 S21 spherical 20.00 7.28( 1.821 24.06 S22 spherical 19.53 0.22 S23 spherical 23.36 1.30 1.618 63.4 (S24 spherical 34.62 0.98 S25 spherical 20.63 2.11 1.806 40.7 S26 spherical 30.93 18.47 S27 spherical Infinity 0.75 1.52 64.2 S28 spherical Infinity 0.33 ImgH spherical Infinity 0.00

[0180] Where R is the radius of curvature of the optical element (such as a lens or cover glass 400), Nd is the refractive index of each optical element when d-line is irradiated, Vd is the Abbe number of the optical element, and TH is the center thickness of the optical element. The center thickness can be understood as the vertical thickness of the optical center point of the lens (the point through which the optical axis passes).

[0181] Wherein, OBJ is the imaging surface of projection lens 200, Stop is aperture 250, S1 is the image-side surface of the first lens G1, S2 is the object-side surface of the first lens G1, S3 is the image-side surface of the second lens G2, S4 is the cementing surface of the cemented lens assembly formed by the second lens G2 and the third lens G3, S5 is the object-side surface of the third lens G3, S6 is the image-side surface of the fourth lens G4, S7 is the object-side surface of the fourth lens G4, S8 is the image-side surface of the fifth lens G5, S9 is the object-side surface of the fifth lens G5, S10 is the image-side surface of the sixth lens G6, S11 is the object-side surface of the sixth lens G6, S12 is the image-side surface of the seventh lens G7, S13 is the object-side surface of the seventh lens G7, S14 is the image-side surface of the eighth lens G8, and S15 is the area between the eighth lens G8 and the ninth lens G9. The cemented surfaces are as follows: S16 is the cemented surface between the ninth lens G9 and the tenth lens G10; S17 is the object side surface of the tenth lens G10; S18 is the image side surface of the eleventh lens G11; S19 is the object side surface of the eleventh lens G11; S20 is the image side surface of the twelfth lens G12; S21 is the cemented surface of the cemented lens group composed of the twelfth lens G12 and the thirteenth lens G13; S22 is the object side surface of the thirteenth lens G13; S23 is the image side surface of the fourteenth lens G14; S24 is the object side surface of the fourteenth lens G14; S25 is the image side surface of the fifteenth lens G15; S26 is the object side surface of the fifteenth lens G15; S27 is the image side surface of the cover glass 400; S28 is the object side surface of the cover glass 400; and ImgH is the imaging surface of the modulation device 320.

[0182] Among them, T0, T6, T11, and T17 have different values ​​under different projection distance states (i.e., the second lens group 220 and the third lens group 230 are located at different positions), and T0 represents the projection distance of the projection lens 200. For example, as shown in Table 2, Table 2 shows the parameters satisfied by the projection lens 200 under three projection distance states.

[0183] First projection distance state Second projection distance state Third projection distance status T0 80 130 1500 T6 5.864 3.5142 0.825 T11 1.1243 3.4785 6.1677 T17 8.900 5.5991 1.65

[0184] Table 3 shows... Figure 2 The optical parameters of the projection lens 200.

[0185] EFLG1(mm) -97.81 EFLG4 (mm) 98.973 EFLG2(mm) -409.55 EFL (mm) 20.5 EFLG3 (mm) 32.94 BFL (mm) 19.55

[0186] Wherein, EFLG1 is the focal length of the first lens group 210, EFLG2 is the focal length of the second lens group 220, EFLG3 is the focal length of the third lens group 230, EFLG4 is the focal length of the fourth lens group 240, EFL is the focal length of the projection lens 200, and BFL is the back focal length of the projection lens 200.

[0187] Figure 5 for Figure 2 The spherical chromatic aberration diagram of the projection lens 200. Figure 5 In the diagram, the vertical axis represents the normalized pupil coordinates, and the horizontal axis represents the aberrations along the axial direction, with units of millimeters. Figure 5 In the diagram, the three curves correspond to the axial aberration curves of light with wavelengths of 625nm, 550nm, and 455nm after passing through the projection lens 200 provided in this embodiment. Figure 5 As can be seen, in the embodiments of this application, the axial aberration can be controlled within -0.3mm to 0.04mm, resulting in good correction and enabling high-definition imaging.

[0188] Figure 6 for Figure 2 The image bokeh curve of the projection lens 200. Figure 6 In the diagram, S represents the field curvature of light with a wavelength of 550 nm in the meridional image plane, and T represents the field curvature of light with a wavelength of 550 nm in the sagittal image plane. From... Figure 6 As can be seen, the projection lens 200 provided in this application embodiment can control the field curvature within -0.05mm to 0mm, and can achieve high-definition imaging.

[0189] Figure 7 for Figure 2 The distortion diagram of the projection lens 200. Figure 7 In the diagram, the solid line represents the distortion value of light with a center wavelength of 550nm passing through the projection lens 200 of this embodiment. From... Figure 7 As can be seen, the projection lens 200 provided in this application embodiment can control the distortion to within 4%, and can achieve high-definition imaging.

[0190] Figure 8 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 9 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 10 This is another structural schematic diagram of the projection device 100 provided in an embodiment of this application. It should be noted that... Figure 8 , Figure 9 and Figure 10 The projection lens 200 is in the long projection distance state, medium projection distance state and short projection distance state respectively.

[0191] See Figure 8 The projection device 100 includes a projection lens 200, an image source 300, and a cover glass 400. The image source 300 includes a modulator 320 and a light source 310 (not shown in the figure). The modulator 320 modulates the light emitted by the light source 310 to obtain image light including image information. The cover glass 400 is disposed between the light-emitting side of the modulator 320 and the light-incoming side of the projection lens 200.

[0192] See also Figure 8 The projection lens 200 includes a first lens group 210, a second lens group 220, an aperture 250, a third lens group 230, and a fourth lens group 240 arranged sequentially from the image side to the object side. The first lens group 210 and the fourth lens group 240 are both fixed lens groups, while the second lens group 220 and the third lens group 230 are both movable lens groups. The second lens group 220 and the third lens group 230 can move relative to the fixed lens group along the optical axis of the projection lens 200 to change the projection distance of the projection lens 200.

[0193] The projection lens 200 can include multiple projection distance states; for example, the projection lens 200 can include a long projection distance state (such as...). Figure 8 As shown), the projection distance status (e.g.) Figure 9 (as shown) and short projection distance state (such as) Figure 10 As shown, by controlling the second lens group 220 and the third lens group 230 to move along the optical axis, the projection lens 200 can switch between any two states among the long projection distance state, the medium projection distance state, and the short projection distance state.

[0194] During the process of changing the projection distance of the projection lens 200 from a first distance to a second distance, the second lens group 220 moves along the direction from the fourth lens group 240 to the first lens group 210, and the third lens group 230 moves along the direction from the first lens group 210 to the fourth lens group 240. The first distance is greater than the second distance, and the first and second distances correspond to the projection distances of the projection lens 200 at two different projection distance states. For example, the first distance could be the projection distance of the projection lens 200 at a long projection distance, and the second distance could be the projection distance of the projection lens 200 at a medium projection distance.

[0195] The first lens group 210 has negative optical power, and its focal length EFG1 = -299.02 mm. The first lens group 210 may include a first lens G1, a second lens G2, a third lens G3, and a fourth lens G4 arranged from the image side to the object side. The first lens G1 is the lens closest to the image side in the first lens group 210, and the second lens G2 and the third lens G3 form a cemented lens group.

[0196] The second lens group 220 has negative optical power and a focal length EFG2 = -272.56 mm. The second lens group 220 may include a fifth lens G5, a sixth lens G6, and a seventh lens G7 arranged from the image side to the object side. The fifth lens G5 is the lens in the second lens group 220 that is closest to the first lens group 210. The sixth lens G6 and the seventh lens G7 form a cemented lens group.

[0197] The third lens group 230 has positive power and a focal length EFG2 = 36.096 mm. The third lens group 230 may include an eighth lens G8, a ninth lens G9, a tenth lens G10, and an eleventh lens G11 arranged from the image side to the object side. The eighth lens G8 is the lens closest to the aperture stop 250 in the third lens group 230. The ninth lens G9, the tenth lens G10, and the eleventh lens G11 constitute a cemented lens group.

[0198] The fourth lens group 240 has positive power and a focal length EFG2 = 96.55 mm. The fourth lens group 240 may include a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, a fifteenth lens G15, and a sixteenth lens G16 arranged from the image side to the object side. The twelfth lens G12 is the lens in the fourth lens group 240 that is closest to the third lens group 230. The thirteenth lens G13 and the fourteenth lens G14 form a cemented lens group.

[0199] The focal length EFL of projection lens 200 is 20.5mm, and the back focal length BFL of projection lens 200 is 19.55mm.

[0200] Table 4 shows Figure 8 The optical parameters of each optical element of the projection device 100 shown.

[0201]

[0202]

[0203] Where R is the radius of curvature of the optical element (such as a lens or cover glass 400), Nd is the refractive index of each optical element when d-line is irradiated, Vd is the Abbe number of the optical element, and TH is the center thickness of the optical element. The center thickness can be understood as the vertical thickness of the optical center point of the lens (the point through which the optical axis passes).

[0204] Wherein, OBJ is the imaging surface of projection lens 200, Stop is aperture 250, S1 is the image-side surface of the first lens G1, S2 is the object-side surface of the first lens G1, S3 is the image-side surface of the second lens G2, S4 is the cementing surface of the cemented lens assembly formed by the second lens G2 and the third lens G3, S5 is the object-side surface of the third lens G3, S6 is the image-side surface of the fourth lens G4, S7 is the object-side surface of the fourth lens G4, S8 is the image-side surface of the fifth lens G5, S9 is the object-side surface of the fifth lens G5, S10 is the image-side surface of the sixth lens G6, S11 is the cementing surface of the cemented lens assembly formed by the sixth lens G6 and the seventh lens G7, S12 is the object-side surface of the seventh lens G7, S13 is the image-side surface of the eighth lens G8, S14 is the object-side surface of the eighth lens G8, S15 is the image-side surface of the ninth lens G9, and S16 is the object-side surface of the ninth lens G8. S17 is the cemented surface between lens G9 and the tenth lens G10; S18 is the object side surface of the eleventh lens G11; S19 is the image side surface of the twelfth lens G12; S20 is the object side surface of the twelfth lens G12; S21 is the image side surface of the thirteenth lens G13; S22 is the cemented surface of the cemented lens group formed by the thirteenth lens G13 and the fourteenth lens G14; S23 is the object side surface of the fourteenth lens G14; S24 is the image side surface of the fifteenth lens G15; S25 is the object side surface of the fifteenth lens G15; S26 is the image side surface of the sixteenth lens G16; S27 is the object side surface of the sixteenth lens G16; S28 is the image side surface of the cover glass 400; S29 is the object side surface of the cover glass 400; and ImgH is the imaging surface of the modulation device 320.

[0205] Among them, T0, T7, T12, and T18 have different values ​​under different projection distance states (i.e., the second lens group 220 and the third lens group 230 are located at different positions), and T0 represents the projection distance of the projection lens 200. For example, as shown in Table 5, Table 5 shows the parameters satisfied by the projection lens 200 under three projection distance states.

[0206] First projection distance state Second projection distance state Third projection distance status T0 80 130 1500 T7 5.864 3.5142 0.825 T12 1.1243 3.4785 6.1677 T18 8.900 5.5991 1.65

[0207] Table 6 shows Figure 8 The optical parameters of the projection lens 200.

[0208]

[0209]

[0210] Wherein, EFLG1 is the focal length of the first lens group 210, EFLG2 is the focal length of the second lens group 220, EFLG3 is the focal length of the third lens group 230, EFLG4 is the focal length of the fourth lens group 240, EFL is the focal length of the projection lens 200, and BFL is the back focal length of the projection lens 200.

[0211] Figure 11 for Figure 8 The spherical chromatic aberration diagram of the projection lens 200. Figure 11 In the diagram, the vertical axis represents the normalized pupil coordinates, and the horizontal axis represents the aberrations along the axial direction, with units of millimeters. Figure 12 In the diagram, the three curves correspond to the axial aberration curves of light with wavelengths of 625nm, 550nm, and 455nm after passing through the projection lens 200 of this embodiment. From... Figure 11 As can be seen, in the embodiments of this application, the axial aberration can be controlled within -0.08mm to 0.05mm, resulting in better correction and enabling high-definition imaging.

[0212] Figure 12 for Figure 8 The image bokeh curve of the projection lens 200. Figure 12 In the diagram, S represents the field curvature of light with a wavelength of 550 nm in the meridional image plane, and T represents the field curvature of light with a wavelength of 550 nm in the sagittal image plane. From... Figure 12 As can be seen, the projection lens 200 provided in this application embodiment can control the field curvature within -0.04mm to 0mm, and can achieve high-definition imaging.

[0213] Figure 13 for Figure 8 The distortion diagram of the projection lens 200. Figure 13 In the diagram, the solid line represents the distortion value of light with a center wavelength of 550nm passing through the projection lens 200 of this embodiment. From... Figure 13 As can be seen, the projection lens 200 provided in this application embodiment can control the distortion to within 4%, and can achieve high-definition imaging.

[0214] Figure 14 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 15 This is another structural schematic diagram of the projection device 100 provided in the embodiments of this application. Figure 16 This is another structural schematic diagram of the projection device 100 provided in an embodiment of this application. It should be noted that... Figure 14 , Figure 14 and Figure 16 The projection lens 200 is in the long projection distance state, medium projection distance state and short projection distance state respectively.

[0215] See Figure 14 The projection device 100 includes a projection lens 200, an image source 300, and a cover glass 400. The image source 300 includes a modulator 320 and a light source 310 (not shown in the figure). The modulator 320 modulates the light emitted by the light source 310 to obtain image light including image information. The cover glass 400 is disposed between the light-emitting side of the modulator 320 and the light-incoming side of the projection lens 200.

[0216] See also Figure 14 The projection lens 200 includes a first lens group 210, a second lens group 220, an aperture 250, a third lens group 230, and a fourth lens group 240 arranged sequentially from the image side to the object side. The first lens group 210 and the fourth lens group 240 are both fixed lens groups, while the second lens group 220 and the third lens group 230 are both movable lens groups. The second lens group 220 and the third lens group 230 can move relative to the fixed lens group along the optical axis of the projection lens 200 to change the projection distance of the projection lens 200.

[0217] The projection lens 200 can include multiple projection distance states; for example, the projection lens 200 can include a long projection distance state (such as...). Figure 14 As shown), the projection distance status (e.g.) Figure 15 (as shown) and short projection distance state (such as) Figure 16 As shown, by controlling the second lens group 220 and the third lens group 230 to move along the optical axis, the projection lens 200 can switch between any two states among the long projection distance state, the medium projection distance state, and the short projection distance state.

[0218] During the process of changing the projection distance of the projection lens 200 from a first distance to a second distance, the second lens group 220 moves along the direction from the fourth lens group 240 to the first lens group 210, and the third lens group 230 moves along the direction from the first lens group 210 to the fourth lens group 240. The first distance is greater than the second distance, and the first and second distances correspond to the projection distances of the projection lens 200 at two different projection distance states. For example, the first distance could be the projection distance of the projection lens 200 at a long projection distance, and the second distance could be the projection distance of the projection lens 200 at a medium projection distance.

[0219] The first lens group 210 has negative optical power and a focal length EFG1 = -76.62 mm. The first lens group 210 may include a first lens G1 and a second lens G2 arranged from the image side to the object side. The first lens G1 is the lens closest to the image side in the first lens group 210, and the second lens G2 is the lens closest to the second lens group 220 in the first lens group 210.

[0220] The second lens group 220 has negative optical power and a focal length EFG2 = -698.61 mm. The second lens group 220 may include a third lens G3, a fourth lens G4, and a fifth lens G5 arranged from the image side to the object side. The third lens G3 is the lens in the second lens group 220 that is closest to the first lens group 210. The fourth lens G4 and the fifth lens G5 form a cemented lens group.

[0221] The third lens group 230 has positive power and a focal length EFG2 = 32.32 mm. The third lens group 230 may include a sixth lens G6, a seventh lens G7, and an eighth lens G8 arranged from the image side to the object side. The sixth lens G6 is the lens closest to the aperture stop 250 in the third lens group 230, and the seventh lens G7 and the eighth lens G8 form a cemented lens group.

[0222] The fourth lens group 240 has positive power and a focal length EFG2 = 97.69 mm. The fourth lens group 240 may include a ninth lens G9, a tenth lens G10, an eleventh lens G11, a twelfth lens G12, and a thirteenth lens G13 arranged from the image side to the object side. The ninth lens G9 is the lens in the fourth lens group 240 that is closest to the third lens group 230. The tenth lens G10 and the eleventh lens G11 form a cemented lens group.

[0223] The focal length EFL of projection lens 200 is 20.5mm, and the back focal length BFL of projection lens 200 is 19.55mm.

[0224] Table 7 shows Figure 14 Optical parameters of each optical element of the projection device 100.

[0225]

[0226] Where R is the radius of curvature of the optical element (such as a lens or cover glass 400), Nd is the refractive index of each optical element when d-line is irradiated, Vd is the Abbe number of the optical element, and TH is the center thickness of the optical element. The center thickness can be understood as the vertical thickness of the optical center point of the lens (the point through which the optical axis passes).

[0227] Wherein, OBJ is the imaging surface of projection lens 200, Stop is aperture 250, S1 is the image-side surface of the first lens G1, S2 is the object-side surface of the first lens G1, S3 is the image-side surface of the second lens G2, S4 is the object-side surface of the second lens G2, S5 is the image-side surface of the third lens G3, S6 is the object-side surface of the third lens G3, S7 is the image-side surface of the fourth lens G4, S8 is the object-side surface of the fourth lens G4, S9 is the cementing surface of the cemented lens assembly formed by the fourth lens G4 and the fifth lens G5, S10 is the image-side surface of the fifth lens G5, S11 is the object-side surface of the fifth lens G5, S12 is the image-side surface of the sixth lens G6, S13 is the object-side surface of the sixth lens G6, S14 is the image-side surface of the seventh lens G7, and S15 is the image-side surface of the seventh lens G7. The cementing surfaces of the cemented lens group formed with the eighth lens G8 are as follows: S16 is the object side surface of the eighth lens G8; S17 is the virtual surface; S18 is the image side surface of the ninth lens G9; S19 is the object side surface of the ninth lens G9; S20 is the image side surface of the tenth lens G10; S21 is the cementing surface of the cemented lens group formed by the tenth lens G10 and the eleventh lens G11; S22 is the object side surface of the eleventh lens G11; S23 is the image side surface of the twelfth lens G12; S24 is the object side surface of the twelfth lens G12; S25 is the image side surface of the thirteenth lens G13; S26 is the object side surface of the thirteenth lens G13; S27 is the image side surface of the cover glass 400; S28 is the object side surface of the cover glass 400; and ImgH is the imaging surface of the modulation device 320.

[0228] Among them, T0, T6, T11, and T17 have different values ​​under different projection distance states (i.e., the second lens group 220 and the third lens group 230 are located at different positions), and T0 represents the projection distance of the projection lens 200. For example, as shown in Table 8, Table 8 shows the parameters satisfied by the projection lens 200 under three projection distance states.

[0229] First projection distance state Second projection distance state Third projection distance status T0 80 130 1500 T6 5.864 3.5142 0.825 T11 1.1243 3.4785 6.1677 T17 8.900 5.5991 1.65

[0230] Table 9 shows... Figure 14 The optical parameters of the projection lens 200.

[0231] EFLG1(mm) -76.62 EFLG4 (mm) 97.69 EFLG2(mm) -698.61 EFL (mm) 20.5 EFLG3 (mm) 32.32 BFL (mm) 19.55

[0232] Wherein, EFLG1 is the focal length of the first lens group 210, EFLG2 is the focal length of the second lens group 220, EFLG3 is the focal length of the third lens group 230, EFLG4 is the focal length of the fourth lens group 240, EFL is the focal length of the projection lens 200, and BFL is the back focal length of the projection lens 200.

[0233] Figure 17 for Figure 14 The spherical chromatic aberration diagram of the projection lens 200. Figure 17In the diagram, the vertical axis represents the normalized pupil coordinates, and the horizontal axis represents the aberrations along the axial direction, with units of millimeters. Figure 17 In the diagram, the three curves correspond to the axial aberration curves of light with wavelengths of 625nm, 550nm, and 455nm after passing through the projection lens 200 of this embodiment. From... Figure 17 As can be seen, in the embodiments of this application, the axial aberration can be controlled within -0.075mm to 0.05mm, resulting in good correction and enabling high-definition imaging.

[0234] Figure 18 for Figure 14 The image bokeh curve of the projection lens 200. Figure 18 In the diagram, S represents the field curvature of light with a wavelength of 550 nm in the meridional image plane, and T represents the field curvature of light with a wavelength of 550 nm in the sagittal image plane. From... Figure 18 As can be seen, the projection lens 200 provided in this application embodiment can control the field curvature within -0.04mm to 0.01mm, and can achieve high-definition imaging.

[0235] Figure 19 for Figure 14 The distortion diagram of the projection lens 200. Figure 19 In the diagram, the solid line represents the distortion value of light with a center wavelength of 550nm passing through the projection lens 200 of this embodiment. From... Figure 19 As can be seen, the projection lens 200 provided in this application embodiment can control the distortion to within 4%, and can achieve high-definition imaging.

[0236] This application also provides a terminal, which includes the projection device 100 of any of the above embodiments.

[0237] The terminal may include, but is not limited to, vehicles and display devices. Display devices may include, but are not limited to, projectors, projection lamps, desktop display devices, etc. Vehicles may include, but are not limited to, cars, trucks, motorcycles, buses, ships, airplanes, helicopters, lawnmowers, recreational vehicles, amusement park vehicles, construction equipment, trams, golf carts, trains, or handcarts, etc.

[0238] In some possible implementations, the terminal also includes a processor electrically connected to the projection device 100. The processor is used to send image data to the image source 300 of the projection device 100, so that the image source 300 generates an image beam. In this way, the terminal can emit an image beam to form an image.

[0239] The processor can be referred to as a front-end processor. A processor includes one or more processing units, such as: an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural network processing unit (NPU). These different processing units can be independent devices or integrated into one or more processors.

[0240] In some possible implementations, the terminal also includes a processor for controlling the movement of the second lens group 220 and the third lens group 230 along the optical axis of the projection lens 200. This allows adjustment of the projection distance of the projection lens 200, thereby determining the image's position and improving user experience.

[0241] In some embodiments, the processor that controls the projection device 100 to emit an image beam may be the same processor that controls the second mirror group 220 and the third mirror group 230 to move along the optical axis.

[0242] In some embodiments, the terminal may include multiple processors, which may include a first processor and a second processor. The first processor may send image data to the image source 300 of the projection device 100 to cause the image source 300 to generate an image beam. The second processor is used to control the second lens group 220 and the third lens group 230 to move along the optical axis to adjust the projection distance of the projection lens 200.

[0243] In some possible implementations, when the terminal is a vehicle, the vehicle includes a display device, which includes a projection device 100. This allows for scenarios such as head-up displays and in-vehicle projection to be implemented in the vehicle.

[0244] The display device can include, but is not limited to, head-up displays (HUDs), in-vehicle displays, and projection headlights. HUDs can be AR-HUDs (augmented reality head-up displays), C-HUDs (combiner head-up displays), W-HUDs (windshield reality head-up displays), PHUDs (panoramic head-up displays), etc. Furthermore, HUDs can be single-focal-plane systems or multi-focal-plane systems.

[0245] In some embodiments, the HUD can project a generated image beam onto the windshield of a vehicle, and the windshield can reflect the image beam to the human eye.

[0246] In some embodiments, the HUD projection device 100 can be installed on the dashboard of a vehicle. The projection device 100 may be installed inside the dashboard, or it may be located on the surface of the dashboard and inside the windshield, or a portion of the projection device 100 may be located inside the dashboard and another portion may be located in the gap between the dashboard and the windshield.

[0247] In some embodiments, the in-vehicle display can project the generated image beam onto the display medium of the vehicle's door glass, rear windshield, or projection screen.

[0248] When both the door windows and the rear windshield receive the image beam, they can receive the same image beam generated by the same in-vehicle display, or they can receive image beams generated by different in-vehicle displays.

[0249] In some possible implementations, there are multiple display devices, including a first display device and a second display device. The projection distance of the projection lens 200 of the first display device is different from that of the projection lens 200 of the second display device. Thus, the projection lens 200 provided in this embodiment can be arranged in different positions on the vehicle, resulting in a wide range of applications and reducing the cost of transportation.

[0250] In some embodiments, one of the first display device and the second display device may be a HUD, and the other may be a vehicle display or a projection headlight, etc.

[0251] When the first display device is a HUD and the second display device is an in-vehicle display, the projection distance of the projection lens 200 of the first display device is greater than the projection distance of the projection lens 200 of the second display device.

[0252] In some embodiments, neither the first display device nor the second display device is a HUD; either the first display device or the second display device can be a projection headlight, an in-vehicle display, or other similar device.

[0253] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances. The terms "first," "second," "third," "fourth," etc. (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0254] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A projection lens (200), characterized in that, It includes a first lens group (210), a second lens group (220), a third lens group (230) and a fourth lens group (240) arranged in sequence from the image side to the object side; Both the first lens group (210) and the fourth lens group (240) are fixed lens groups. Both the first lens group (210) and the fourth lens group (240) include at least one lens. Both the first lens group (210) and the fourth lens group (240) have optical power. The first lens group (210) is the lens group closest to the image side in the projection lens (200), and the fourth lens group (240) is the lens group closest to the object side in the projection lens (200); Both the second lens group (220) and the third lens group (230) include at least one lens. Both the second lens group (220) and the third lens group (230) have optical power. Both the second lens group (220) and the third lens group (230) can move along the optical axis direction of the projection lens (200) relative to the fixed lens group to change the projection distance of the projection lens (200).

2. The projection lens (200) according to claim 1, characterized in that, The projection lens (200) further includes an aperture (250), and the aperture (250) is arranged on the optical path between the second lens group (220) and the third lens group (230).

3. The projection lens (200) according to claim 1 or 2, characterized in that, The projection lens (200) satisfies the relation: |EFLG2| > |EFLG3|; where, EFLG2 is the focal length of the second lens group (220), and EFLG3 is the focal length of the third lens group (230).

4. The projection lens (200) according to any one of claims 1-3, characterized in that, The projection lens (200) satisfies the relation: 10 < |EFLG2 / EFL| < 80; where, EFL is the focal length of the projection lens (200), and EFLG2 is the focal length of the second lens group (220).

5. The projection lens (200) according to any one of claims 1-4, characterized in that, The projection lens (200) satisfies the relation: 0.8 < |EFLG3 / EFL| < 2.6; where, EFL is the focal length of the projection lens (200), and EFLG3 is the focal length of the third lens group (230).

6. The projection lens (200) according to any one of claims 1-5, characterized in that, The projection lens (200) satisfies the relation: 10mm < EFL < 25mm.

7. The projection lens (200) according to any one of claims 1-6, characterized in that, The projection lens (200) satisfies the relation: 0 < D1 < 6mm; where, D1 is the moving stroke of the second lens group (220) moving along the optical axis direction.

8. The projection lens (200) according to any one of claims 1-7, characterized in that, The projection lens (200) satisfies the relation: 0 < D2 < 8mm; where, D2 is the moving stroke of the third lens group (230) moving along the optical axis direction.

9. The projection lens (200) according to any one of claims 1-8, characterized in that, Both the first lens group (210) and the second lens group (220) have negative optical power, and both the third lens group (230) and the fourth lens group (240) have positive optical power.

10. The projection lens (200) according to any one of claims 1-9, characterized in that, During the process of changing the projection distance of the projection lens (200), the moving direction of the second lens group (220) is opposite to the moving direction of the third lens group (230).

11. The projection lens (200) according to claim 10, characterized in that, During the process of the projection distance of the projection lens (200) changing from a first distance to a second distance, the second lens group (220) moves along the direction from the first lens group (210) to the fourth lens group (240), and the third lens group (230) moves along the direction from the fourth lens group (240) to the first lens group (210); wherein, the first distance is greater than the second distance.

12. The projection lens (200) according to any one of claims 1-11, characterized in that, The projection lens (200) also includes at least one cemented lens assembly, which is formed by cementing together at least two adjacent lenses; At least one of the second lens group (220) and the third lens group (230) includes the cemented lens group.

13. The projection lens (200) according to any one of claims 1-12, characterized in that, The first lens group (210), the second lens group (220), the third lens group (230) and the fourth lens group (240) each have multiple lenses.

14. The projection lens (200) according to claim 13, characterized in that, The second lens group (220) has at least three lenses; and / or the third lens group (230) has at least three lenses.

15. The projection lens (200) according to claim 13 or 14, characterized in that, The first lens group (210) has at least two lenses; and / or the fourth lens group (240) has at least five lenses.

16. The projection lens (200) according to any one of claims 1-15, characterized in that, The projection lens (200) has a lens number greater than or equal to 13 and less than or equal to 16.

17. A projection device (100), characterized in that, Includes an image source (300) and a projection lens (200) as described in any one of claims 1-16; The image source (300) is used to generate an image beam that can form an image and to project the image beam onto the projection lens (200); The fourth lens group (240) of the projection lens (200) is used to receive the image beam generated by the image source (300).

18. A terminal, characterized in that, Includes the projection device (100) as described in claim 17.

19. The terminal according to claim 18, characterized in that, The terminal is a vehicle, the vehicle includes a display device, and the display device includes the projection device (100).

20. The terminal according to claim 19, characterized in that, The number of display devices is multiple, including a first display device and a second display device. The projection distance of the projection lens (200) of the first display device is different from the projection distance of the projection lens (200) of the second display device.

Images