A fixed focus lens

Abstract

The invention discloses a fixed-focus lens, and relates to the technical field of fixed-focus lenses. The invention comprises an imaging surface and a front end hole of the lens, wherein the front end hole of the lens is located on the left side of the imaging surface, and a first lens, a second lens, a third lens group and a fourth lens are sequentially arranged between the imaging surface and the front end hole of the lens from left to right. The design of the invention takes into account the compactness of the optical system, and the spacing between the first lens and the second lens, and the fitting design between the first lens and the second lens reduce the volume of the lens while ensuring the optical performance. This design can reduce the overall size and weight of the lens, improve the portability of the lens, and is suitable for application scenarios that require a long focal length but have requirements on the weight and volume of the lens. At the same time, the lens has a small number of lenses, and the lenses are concentrated. At the same time, the third lens group is installed in close contact, which is convenient to install and has a low production cost. It can minimize optical distortion and ensure the clarity, contrast and edge sharpness of the image.

Description

Technical Field

[0001] The present invention relates to the technical field of fixed-focus lenses, and in particular to a fixed-focus lens. Background Art

[0002] A fixed-focus lens is an optical lens with a fixed focal length. It cannot adjust the focal length to change the shooting angle like a zoom lens. Due to its simple optical design, it usually performs well in image quality and is widely used in portrait photography, landscape photography, night photography and other fields. Fixed-focus lenses usually have a large aperture, can provide good shooting effects in low-light environments, and have advantages in controlling shallow depth of field.

[0003] The main problems faced by traditional fixed-focus lens technology:

[0004] (1) Aberration control: Even for simple optical designs, issues such as chromatic aberration, spherical aberration, and distortion still need to be considered. Especially in large aperture designs, aberration control becomes a key technical issue.

[0005] (2) Arrangement of optical elements: Fixed-focus lenses are usually composed of multiple lenses. How to reasonably design the arrangement structure of optical elements to ensure a larger aperture while maintaining high image quality is an important issue in lens design.

[0006] (3) Scattered light and ghosting: When light passes through an optical lens, it may reflect or scatter, resulting in reduced image quality. These problems are particularly prominent in low-light environments and affect the performance of the lens.

[0007] (4) An important feature of fixed-focus lenses is their large aperture design. The maximum aperture of many fixed-focus lenses can reach f / 1.2, f / 1.4 or even f / 1.0, which can provide an extremely shallow depth of field and enable high-quality shooting in low-light environments. Although the large aperture design helps improve the performance of the lens, it also increases the difficulty of optical design. For example, how to effectively reduce the optical distortion caused by the large aperture and reduce the chromatic aberration in the image has become a key issue in the design.

[0008] In a Chinese patent (application number: CN202110932421.8), a fixed-focus lens is disclosed, including a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power, and a fourth lens with negative optical power arranged in sequence from the object side to the image side along the optical axis. The patent uses plastic lenses. Although it can reduce the weight of the lens, the precision of plastic lenses is low, which may affect the imaging quality, especially in high-resolution application scenarios; although aspherical lenses are used to control aberrations, there are still possible optical distortions in the lens design, especially in the edge area. Since the first and fourth lenses have negative optical power, they may cause more significant aberrations, especially at large apertures; the optical path between multiple lenses in the lens may cause a decrease in transmittance, especially if a combination of a glass spherical lens (such as the second lens) and a plastic lens is used, which may increase internal reflections and light losses, affecting the brightness and clarity of the image. Summary of the invention

[0009] The purpose of the present invention is to solve the above problem and provide a fixed-focus lens.

[0010] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0011] A fixed-focus lens comprises an imaging surface and a front end hole of the lens, wherein the front end hole of the lens is located on the left side of the imaging surface, and a first lens, a second lens, a third lens group and a fourth lens are arranged in sequence from left to right between the imaging surface and the front end hole of the lens, wherein the object side surface of the first lens is a convex surface, and the image side surface is a convex surface, the object side surface of the second lens is a convex surface, and the image side surface is a concave surface, the third lens group consists of a first lens and a second lens, wherein the first lens and the second lens are arranged from left to right and are bonded to each other, the object side surface of the first lens is a convex surface, and the image side surface is a concave surface, the object side surface of the second lens is a convex surface, and the image side surface is a concave surface, and the object side surface of the fourth lens is a convex surface, and the image side surface is a concave surface.

[0012] Furthermore, the distance between the front end hole of the lens and the object side of the first lens is 34-36 mm, the distance between the image side of the first lens and the object side of the second lens is 0.2-0.3 mm, the distance between the image side of the second lens and the object side of lens one is 0.2-0.3 mm, the distance between the image side of lens two and the object side of the fourth lens is 2.6-2.8 mm, and the distance between the image side of the fourth lens and the imaging plane is 4.4-4.6 mm.

[0013] Furthermore, the aperture of the first lens is 24 mm, the focal ratio is f9, the radius of curvature of the object side is 67.7 mm, the radius of curvature of the image side is 67.7 mm, and the center thickness is 3.7±0.03 mm.

[0014] Furthermore, the aperture of the second lens is 24 mm, the focal ratio is f9, the radius of curvature of the object side is 24.83 mm, the radius of curvature of the image side is 164.4 mm, and the center thickness is 4.6±0.03 mm.

[0015] Furthermore, the aperture of lens one is 20.5 mm, the focal ratio is f9, the radius of curvature of the object side is 14.19 mm, the radius of curvature of the image side is 84.4 mm, and the center thickness is 5.1±0.03 mm; the aperture of lens two is 18.4 mm, the focal ratio is f9, the radius of curvature of the object side is 84.4 mm, the radius of curvature of the image side is 8.75 mm, and the center thickness is 1.2±0.03 mm.

[0016] Furthermore, the aperture of the third lens is 16 mm, the focal ratio is f9, the radius of curvature of the object side is 12.837 mm, the radius of curvature of the image side is 81.6 mm, and the center thickness is 3.8±0.03 mm.

[0017] Furthermore, the aperture of the imaging surface is 10.9 mm.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The design of the lens of the present invention adopts multiple lens groups, especially the third lens group consists of lens one and lens two, which effectively reduces common aberrations and improves imaging quality. By properly designing the curvature radius and thickness of each lens, optical distortion can be minimized to ensure image clarity, contrast and edge sharpness.

[0020] 2. The design of the present invention takes into account the compactness of the optical system. The spacing between the first lens and the second lens and the fitting design between lens one and lens two reduce the size of the lens while ensuring the optical performance. This design can reduce the overall size and weight of the lens and improve the portability of the lens. It is suitable for application scenarios that require a long focal length but have requirements on the weight and volume of the lens. At the same time, the lens has a small number of lenses and the lenses are concentrated. At the same time, the third lens group is installed in close contact, which is easy to install and has a low production cost.

[0021] 3. The present invention can effectively control chromatic aberration and distortion by designing a reasonable lens curvature, thickness and spacing between lenses, making imaging more accurate and color reproduction more realistic. The focal length ratio of the lens is f9, which is moderate and can provide a good depth of field effect. It is suitable for a variety of shooting scenes, especially in static shooting that requires clarity and sharpness. The carefully designed aperture and center thickness parameters help the lens provide consistent optical performance under different lighting conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a schematic diagram of the lens structure of the present invention;

[0023] Figure 2 is a field curvature distortion diagram of the present invention;

[0024] Figure 3 is a point diagram of the present invention;

[0025] Figure 4 is a color difference diagram of the present invention;

[0026] Figure 5 is a magnification chromatic aberration diagram of the present invention;

[0027] Figure 6 It is the grid distortion map of the present invention.

[0028] Reference numerals: 1, first lens; 2, second lens; 3, third lens group; 31, lens one; 32, lens two; 4, fourth lens; 5, imaging plane; 6, front end hole of lens. DETAILED DESCRIPTION

[0029] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] Embodiment 1, as Figure 1 As shown, a fixed-focus lens comprises an imaging surface 5 and a lens front end hole 6, wherein the lens front end hole 6 is located on the left side of the imaging surface 5, and a first lens 1, a second lens 2, a third lens group 3 and a fourth lens 4 are sequentially arranged between the imaging surface 5 and the lens front end hole 6 from left to right. The object side surface of the first lens 1 is a convex surface, and the image side surface is a convex surface, the object side surface of the second lens 2 is a convex surface, and the image side surface is a concave surface, the third lens group 3 is composed of a lens 1 31 and a lens 2 32, which are arranged from left to right and fit each other, the object side surface of the lens 1 31 is a convex surface, and the image side surface is a concave surface, the object side surface of the lens 2 32 is a convex surface, and the image side surface is a concave surface, and the object side surface of the fourth lens 4 is a convex surface, and the image side surface is a concave surface.

[0031] Furthermore, the distance between the front end hole 6 of the lens and the object side of the first lens 1 is 34-36 mm, the distance between the image side of the first lens 1 and the object side of the second lens 2 is 0.2-0.3 mm, the distance between the image side of the second lens 2 and the object side of the lens 1 31 is 0.2-0.3 mm, the distance between the image side of the lens 2 32 and the object side of the fourth lens 4 is 2.6-2.8 mm, and the distance between the image side of the fourth lens 4 and the imaging plane 5 is 4.4-4.6 mm.

[0032] Embodiment 2, as Figure 1-Figure 6As shown, a fixed-focus lens comprises an imaging surface 5 and a lens front end hole 6, wherein the lens front end hole 6 is located on the left side of the imaging surface 5, and a first lens 1, a second lens 2, a third lens group 3 and a fourth lens 4 are sequentially arranged between the imaging surface 5 and the lens front end hole 6 from left to right. The object side surface of the first lens 1 is a convex surface, and the image side surface is a convex surface, the object side surface of the second lens 2 is a convex surface, and the image side surface is a concave surface, the third lens group 3 is composed of a lens 1 31 and a lens 2 32, which are arranged from left to right and fit each other, the object side surface of the lens 1 31 is a convex surface, and the image side surface is a concave surface, the object side surface of the lens 2 32 is a convex surface, and the image side surface is a concave surface, and the object side surface of the fourth lens 4 is a convex surface, and the image side surface is a concave surface.

[0033] The distance between the front end hole 6 of the lens and the object side of the first lens 1 is 35 mm, the distance between the image side of the first lens 1 and the object side of the second lens 2 is 0.25 mm, the distance between the image side of the second lens 2 and the object side of the lens one 31 is 0.25 mm, the distance between the image side of the lens two 32 and the object side of the fourth lens 4 is 2.7 mm, and the distance between the image side of the fourth lens 4 and the imaging plane 5 is 4.51 mm.

[0034] The first lens 1 has an aperture of 24 mm, a focal ratio of f9, a curvature radius of the object side surface of 67.7 mm, a curvature radius of the image side surface of 67.7 mm, and a center thickness of 3.7±0.03 mm.

[0035] The second lens 2 has an aperture of 24 mm, a focal ratio of f9, a curvature radius of the object side surface of 24.83 mm, a curvature radius of the image side surface of 164.4 mm, and a center thickness of 4.6±0.03 mm.

[0036] The aperture of lens 1 31 is 20.5 mm, the focal ratio is f9, the radius of curvature of the object side is 14.19 mm, the radius of curvature of the image side is 84.4 mm, and the center thickness is 5.1±0.03 mm. The aperture of lens 2 32 is 18.4 mm, the focal ratio is f9, the radius of curvature of the object side is 84.4 mm, the radius of curvature of the image side is 8.75 mm, and the center thickness is 1.2±0.03 mm.

[0037] The fourth lens 4 has an aperture of 16 mm, a focal ratio of f9, a curvature radius of the object side surface of 12.837 mm, a curvature radius of the image side surface of 81.6 mm, and a center thickness of 3.8±0.03 mm.

[0038] The diameter of the imaging surface 5 is 10.9 mm.

[0039] Optical parts parameter table

[0040]

[0041] The design of the lens of the present invention adopts multiple groups of lenses, especially the third lens group 3 is composed of lens 1 31 and lens 2 32, which effectively reduces common aberrations and improves imaging quality. By properly designing the radius of curvature and thickness of each lens, optical distortion can be minimized to ensure image clarity, contrast and edge sharpness. The design of the present invention takes into account the compactness of the optical system. The spacing between the first lens 1 and the second lens 2 and the fitting design between the lens 1 31 and the lens 2 32 reduce the volume of the lens while ensuring optical performance. This design can reduce the overall size and weight of the lens, improve the portability of the lens, and is suitable for application scenarios that require a long focal length but have requirements on the weight and volume of the lens. At the same time, the lens has a small number of lenses and the lenses are concentrated. At the same time, the third lens group 3 is installed in close contact, which is convenient to install and has a low production cost. The focal length ratio of the lens is f9, which is moderate and can provide a good depth of field effect, and is suitable for a variety of shooting scenes. In particular, it performs well in static shooting that requires clarity and sharpness. The carefully designed aperture and center thickness parameters help the lens provide consistent optical performance under different lighting conditions.

[0042] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fixed-focus lens, comprising an imaging surface (5) and a lens front end hole (6), characterized in that: The front end hole (6) of the lens is located on the left side of the imaging surface (5); a first lens (1), a second lens (2), a third lens group (3) and a fourth lens (4) are arranged in sequence from left to right between the imaging surface (5) and the front end hole (6); the object side surface of the first lens (1) is a convex surface and the image side surface is a convex surface; the object side surface of the second lens (2) is a convex surface and the image side surface is a concave surface; the third lens group (3) is composed of a first lens (31) and a second lens (32); the first lens (31) and the second lens (32) are arranged from left to right and are bonded to each other; the object side surface of the first lens (31) is a convex surface and the image side surface is a concave surface; the object side surface of the second lens (32) is a convex surface and the image side surface is a concave surface; the object side surface of the fourth lens (4) is a convex surface and the image side surface is a concave surface; The distance between the front end hole (6) of the lens and the object side of the first lens (1) is 34-36 mm, the distance between the image side of the first lens (1) and the object side of the second lens (2) is 0.2-0.3 mm, the distance between the image side of the second lens (2) and the object side of the first lens (31) is 0.2-0.3 mm, the distance between the image side of the second lens (32) and the object side of the fourth lens (4) is 2.6-2.8 mm, and the distance between the image side of the fourth lens (4) and the imaging surface (5) is 4.4-4.6 mm.

2. The fixed-focus lens according to claim 1, characterized in that: The aperture of the first lens (1) is 24 mm, the radius of curvature of the object side is 67.7 mm, the radius of curvature of the image side is 67.7 mm, and the center thickness is 3.7±0.03 mm.

3. The fixed-focus lens according to claim 1, characterized in that: The aperture of the second lens (2) is 24 mm, the radius of curvature of the object side is 24.83 mm, the radius of curvature of the image side is 164.4 mm, and the center thickness is 4.6±0.03 mm.

4. The fixed-focus lens according to claim 1, characterized in that: The aperture of the lens 1 (31) is 20.5 mm, the radius of curvature of the object side is 14.19 mm, the radius of curvature of the image side is 84.4 mm, and the center thickness is 5.1±0.03 mm. The aperture of the lens 2 (32) is 18.4 mm, the radius of curvature of the object side is 84.4 mm, the radius of curvature of the image side is 8.75 mm, and the center thickness is 1.2±0.03 mm.

5. The fixed-focus lens according to claim 1, characterized in that: The third lens (4) has an aperture of 16 mm, a curvature radius of the object side surface of 12.837 mm, a curvature radius of the image side surface of 81.6 mm, and a center thickness of 3.8±0.03 mm.

6. The fixed-focus lens according to claim 1, characterized in that: The aperture of the imaging surface (5) is 10.9 mm.

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