Large-aperture trinocular projection lens

Abstract

The utility model discloses a big aperture three group element projection lens, include: spherical lens, lens group, diaphragm and aspherical lens, the spherical lens is the crescent lens with positive focal length, the spherical lens is used for making the image surface more close to the position of optical not halo point to reduce spherical aberration and coma, the lens group includes the concave lens with negative optical power and the convex lens with positive optical power, and the material quality of concave lens is high fold high dispersion material, the convex lens is high fold low dispersion material, and the lens group is used for reducing spherical aberration and chromatic aberration, the diaphragm is used for controlling the beam aperture, the aspherical lens is used for compensating the spherical aberration, coma and high order aberration of system, the spherical lens, convex lens, concave lens, diaphragm aspherical lens are sequentially arranged along the optical axis direction from the object side to the image side, and the utility model has the advantages that high light efficiency and high image quality are satisfied simultaneously.

Description

Technical Field

[0001] This utility model belongs to the field of automotive lighting technology, specifically relating to a large-aperture three-element projection lens. Background Technology

[0002] With the development of themes such as intelligent sensing and safe driving in the automotive field, headlights, which serve as "glasses" for nighttime driving, are playing an increasingly important role in driving safety. Their functions have also evolved from simple illumination to adaptive high beams, and now to more intelligent and pixelated projection headlights.

[0003] Currently, pixelated and intelligent projection headlights mainly utilize Digital Light Processing (DLP) projection technology and Micro-LED. Micro-LED, with its advantages of fast response speed and long lifespan, is gradually becoming a new trend in the industry. However, due to the large emission angle of Micro-LED light sources, the system needs a sufficiently large aperture to collect the beam. Simultaneously, the large emission area of ​​Micro-LEDs results in a wider field of view, posing greater challenges to the design of the projection lens. To simultaneously meet the requirements of light efficiency and image quality, a large-aperture three-element projection lens is proposed. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] Therefore, this utility model proposes a large-aperture three-element projection lens, which has the advantages of simultaneously satisfying high light efficiency and high image quality.

[0006] According to an embodiment of the present invention, a large-aperture three-element projection lens includes: a spherical lens, a lens group, an aperture stop, and an aspherical lens; the spherical lens is a meniscus lens with a positive focal length, used to bring the image plane closer to the optical vignetting point, thereby reducing spherical aberration and coma; the lens group includes a concave lens with negative optical power and a convex lens with positive optical power, wherein the concave lens is made of a high-refractive-index, high-dispersion material, and the convex lens is made of a high-refractive-index, low-dispersion material, and the lens group is used to reduce spherical aberration and chromatic aberration; the aperture stop is used to control the beam aperture, limiting the system volume while ensuring optical efficiency; the aspherical lens is used to compensate for the system's spherical aberration, coma, and higher-order aberrations; the spherical lens, convex lens, concave lens, aperture stop, and aspherical lens are arranged sequentially from the object side to the image side along the optical axis.

[0007] According to one embodiment of the present invention, the concave lens and the convex lens are either fitted together or separated.

[0008] According to one embodiment of the present invention, the radius of curvature of the outer surface S7 of the spherical lens is greater than that of the inner surface S8, and the bending direction is towards the image plane. The material used is a high-refractive-index, low-dispersion material with a refractive index between 1.5 and 1.8 and an Abbe number between 30 and 70. By using a specific radius of curvature and bending direction, the image plane is made closer to the optical vignetting point, thereby reducing spherical aberration and coma. At the same time, this bending direction can correct the astigmatism and field curvature of the system, thereby controlling the distortion of the system to within 5%.

[0009] According to one embodiment of the present invention, the focal length f1 of the aspherical lens and the system focal length EFL satisfy 3 > |f1 / EFL| > 1.5; the refractive index of the aspherical lens is between 1.45 and 1.65, and the Abbe number is between 45 and 65. Using a higher Abbe number will not introduce large chromatic aberration into the system. At the same time, the optical surfaces on both sides are aspherical, which can effectively compensate for the spherical aberration, coma, and higher-order aberrations of the system, thereby enabling the overall image quality of the system to reach a high level.

[0010] According to one embodiment of this utility model, the combined focal length f3 of the lens group and the system focal length EFL satisfy 1.5 < |f3 / EFL| < 3. The refractive index of the concave lens is between 1.6 and 1.9, and the Abbe number is between 17 and 30; the refractive index of the convex lens is between 1.5 and 1.8, and the Abbe number is between 30 and 70. Both are high-refractive-index materials, which can effectively reduce the contribution of spherical aberration. At the same time, by combining different Abbe numbers, the concave lens can contribute a larger negative chromatic aberration, while the convex lens contributes a smaller positive chromatic aberration, thereby correcting the positive chromatic aberration of the entire system and controlling the red-green and blue-green differences of the system within ±20µm.

[0011] According to one embodiment of the present invention, the aspherical lens is made of plastic.

[0012] According to one embodiment of the present invention, the spherical lens is made of glass.

[0013] According to one embodiment of the present invention, the concave lens and the convex lens are connected by a bonding method when they are attached.

[0014] The beneficial effects of this utility model are that it uses spherical lenses, lens groups, aperture stops and aspherical lenses to respectively reduce spherical aberration and coma of the optical system, control the beam aperture to limit the system volume while ensuring optical efficiency, reduce spherical aberration and chromatic aberration, and compensate for spherical aberration, reduce coma and higher-order aberrations of the system; thus achieving high light efficiency and high image quality projection.

[0015] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.

[0016] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the following description of the embodiments with accompanying drawings, in which:

[0018] Figure 1 This is a schematic diagram of the structure of the concave lens and convex lens of this utility model when they are attached together;

[0019] Figure 2 This is a schematic diagram of the overall structural system parameters of this utility model;

[0020] Figure 3 This is a schematic diagram of the surface parameters of each structure when the concave lens and convex lens of this utility model are attached together;

[0021] Figure 4 This is a schematic diagram of the distortion when the concave lens and convex lens of this utility model are attached together;

[0022] Figure 5 This is a schematic diagram of the projection performance when the concave lens and convex lens of this utility model are attached together;

[0023] Figure 6 This is a schematic diagram of the chromatic aberration along the vertical axis when the concave lens and convex lens of this utility model are fitted together;

[0024] Figure 7 This is a schematic diagram of the relative illumination when the concave lens and convex lens of this utility model are attached together;

[0025] Figure 8 This is a schematic diagram of the parameters of the aspherical lens when the concave lens and convex lens of this utility model are attached together;

[0026] Figure 9 This is a schematic diagram of the structure of the present invention when the concave lens and the convex lens are set separately;

[0027] Figure 10 This is a schematic diagram of the surface parameters of each structure when the concave lens and convex lens of this utility model are set separately;

[0028] Figure 11 This is a schematic diagram of the parameters of the aspherical lens when the concave lens and convex lens of this utility model are attached together;

[0029] Figure 12 This is a schematic diagram of the distortion when the concave lens and convex lens of this utility model are attached together;

[0030] Figure 13 This is a schematic diagram of the projection performance when the concave lens and convex lens of this utility model are set separately;

[0031] Figure 14 This is a schematic diagram of the chromatic aberration along the vertical axis when the concave lens and convex lens of this utility model are set separately;

[0032] Figure 15 This is a schematic diagram of the relative illumination when the concave lens and convex lens of this utility model are set separately;

[0033] Figure label:

[0034] 1. Aspherical lens; 2. Aperture stop; 3. Lens group; 31. Concave lens; 32. Convex lens; 4. Spherical lens. Detailed Implementation

[0035] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0036] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0037] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] The large-aperture three-element projection lens of this utility model is described in detail below with reference to the accompanying drawings.

[0039] like Figures 1-15 As shown, the large-aperture three-element projection lens according to an embodiment of the present invention includes: a spherical lens 4, a lens group 3, an aperture stop 2, and an aspherical lens 1; the spherical lens 4 is a meniscus lens with a positive focal length, used to bring the image plane closer to the optical vignetting point, thereby reducing spherical aberration and coma; the lens group 3 includes a concave lens 31 with negative optical power and a convex lens 32 with positive optical power, and the concave lens 31 is made of a high-refractive-index, high-dispersion material, and the convex lens 32 is made of a high-refractive-index, low-dispersion material, the lens group 3 is used to reduce spherical aberration and chromatic aberration; from the light incident to the light exit direction, the aperture stop 2 is located in front of the aspherical lens 1, which can effectively control the beam aperture and avoid excessive volume; the aspherical lens 1 is used to compensate for the spherical aberration, coma, and higher-order aberrations of the system; the spherical lens 4, the convex lens 32, the concave lens 31, the aperture stop 2, and the aspherical lens 1 are arranged sequentially from the object side to the image side along the optical axis.

[0040] In this embodiment, a spherical lens 4, a lens group 3, an aperture stop 2, and an aspherical lens 1 are used to reduce spherical aberration and coma of the optical system, limit the beam aperture to reduce the overall volume and ensure optical writing efficiency, reduce spherical aberration and chromatic aberration, and compensate for spherical aberration, coma, and higher-order aberrations of the system; thus achieving high light efficiency and high image quality projection.

[0041] The concave lens 31 and the convex lens 32 are either fitted together or separated.

[0042] The outer surface S7 of the spherical lens 4 has a larger radius of curvature than the inner surface S8, with the curvature pointing towards the image plane. It is made of a high-refractive-index, low-dispersion material with a refractive index between 1.5 and 1.8 and an Abbe number between 30 and 70. By using a specific radius of curvature and curvature direction, the image plane is brought closer to the optically vignetting point, thereby reducing spherical aberration and coma. Simultaneously, this curvature direction can correct astigmatism and field curvature, thus keeping the system's distortion below 5%. Distortion reflects the degree of deformation between the projected pattern and the original image, such as... Figure 4 and Figure 12 As shown, the horizontal axis represents the distortion ratio, and the vertical axis represents the relative field of view. The distortion of this scheme at the maximum field of view is 3%.

[0043] The focal length f1 of the aspherical lens 1 and the system focal length EFL satisfy 3 > |f1 / EFL| > 1.5; the refractive index of the aspherical lens 1 is between 1.45 and 1.65, and the Abbe number is between 45 and 65. Using a higher Abbe number will not introduce large chromatic aberration into the system. At the same time, the optical surfaces on both sides are aspherical, which can effectively compensate for the spherical aberration, coma and higher-order aberrations of the system, so that the overall image quality of the system can reach a high level.

[0044] The formula for aspherical lens 1 is as follows:

[0045] When the concave lens 31 and the convex lens 32 are fitted together, the parameters are as follows: Figure 8 As shown; when the concave lens 31 and the convex lens 32 are set separately, the parameters are as follows: Figure 11 As shown.

[0046] The combined focal length f3 of lens group 3 and the system focal length EFL satisfy 1.5 < |f3 / EFL| < 3. The refractive index of concave lens 31 is between 1.6 and 1.9, and the Abbe number is between 17 and 30. The refractive index of convex lens 32 is between 1.5 and 1.8, and the Abbe number is between 30 and 70. Both are high-refractive-index materials, which can effectively reduce the contribution of spherical aberration. At the same time, by combining different Abbe numbers, concave lens 31 can contribute a larger negative chromatic aberration, while convex lens 32 can contribute a smaller positive chromatic aberration, thereby correcting the positive chromatic aberration of the entire system and controlling the red-green and blue-green differences of the system within ±20um.

[0047] The aspherical lens 1 is made of plastic.

[0048] Spherical lens 4 is made of glass.

[0049] When the concave lens 31 and the convex lens 32 are attached, they are connected by a bonding method.

[0050] like Figure 5 and Figure 13 As shown, this reflects the projection performance under different fields of view. The horizontal axis represents the characteristic frequency, with units of lp / mm (line pairs per mm). The higher the value, the more detail the object has. The vertical axis represents the transfer function (MTF) value; the higher the value, the higher the contrast of the pattern. Figure 5 and Figure 13 This indicates that the MTF of a field of view within 9.6° reaches above 0.5 at 6.25 lp / mm.

[0051] like Figure 6 and Figure 14 As shown, the color border width of the imaging pattern is reflected, where the horizontal axis represents the color difference value and the vertical axis represents the relative value of the field of view. At the edge of the field of view, the blue-green difference is 7 μm and the red-green difference is 7.6 μm.

[0052] like Figure 7 and Figure 15 As shown, this reflects the decrease in illuminance caused by vignetting in each field of view. The horizontal axis represents the field of view angle, and the vertical axis represents the relative illuminance. In the maximum field of view, the relative illuminance can reach more than 70%.

[0053] By using an aspherical lens 1, an aperture 2, a lens group 3, and a spherical lens 4, spherical aberration, coma, field curvature, distortion, and chromatic aberration are effectively reduced, achieving requirements such as large aperture, large field of view, high image quality, and long back focal length. The system's F-number is between 0.6 and 0.8, and the full field of view can reach ±10° to ±20°. Within 80% of the field of view, MTF > 0.3 @ 6.25 lp / mm can be achieved, and the back focal length (BFL) can be 2 to 8 mm. The system length is also effectively shortened, achieving a total length (TTL) to focal length (EFL) ratio of TTL / EFL < 2.5.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A large-aperture three-element projection lens, characterized in that, include: The spherical lens (4) is a meniscus lens with a positive focal length. The spherical lens (4) is used to make the image plane closer to the optical vignetting point, thereby reducing spherical aberration and coma. The lens group (3) includes a concave lens (31) with negative optical power and a convex lens (32) with positive optical power. The concave lens (31) is made of a high-refractive-index, high-dispersion material, and the convex lens (32) is made of a high-refractive-index, low-dispersion material. The lens group (3) is used to reduce spherical aberration and chromatic aberration. Aperture (2), wherein the aperture (2) is used to control the beam aperture; Aspherical lens (1), the aspherical lens (1) is used to compensate for spherical aberration, coma and higher-order aberrations of the system; The spherical lens (4), convex lens (32), concave lens (31), aperture (2), and aspherical lens (1) are arranged sequentially from the object side to the image side along the optical axis.

2. The large-aperture three-element projection lens according to claim 1, characterized in that, The concave lens (31) and the convex lens (32) are either fitted together or separated.

3. The large-aperture three-element projection lens according to claim 2, characterized in that, The outer surface S7 of the spherical lens (4) has a larger radius of curvature than the inner surface S8, and the bending direction is towards the image plane. Its refractive index is between 1.5 and 1.8, and its Abbe number is between 30 and 70.

4. The large-aperture three-element projection lens according to claim 3, characterized in that, The focal length f1 of the aspherical lens (1) and the system focal length EFL satisfy 3 > |f1 / EFL| > 1.5; the refractive index of the aspherical lens (1) is between 1.45 and 1.65, and the Abbe number is between 45 and 65.

5. The large-aperture three-element projection lens according to claim 2, characterized in that, The combined focal length f3 of the lens group (3) and the system focal length EFL satisfy 1.5 < |f3 / EFL| < 3, wherein the refractive index of the concave lens (31) is between 1.6 and 1.9 and the Abbe number is between 17 and 30; the refractive index of the convex lens (32) is between 1.5 and 1.8 and the Abbe number is between 30 and 70.

6. The large-aperture three-element projection lens according to claim 1, characterized in that, The aspherical lens (1) is made of plastic.

7. The large-aperture three-element projection lens according to claim 1, characterized in that, The spherical lens (4) is made of glass.

8. The large-aperture three-element projection lens according to claim 1, characterized in that, The concave lens (31) and the convex lens (32) are connected by a bonding method when they are attached.

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