A fixed focus lens

Abstract

The application discloses a fixed-focus lens which comprises, in order from the object side to the image side along the optical axis, a first lens with negative refractive power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative refractive power, the object side of which is a concave surface and the image side of which is a convex surface; a third lens with positive refractive power, the object side of which is a concave surface and the image side of which is a convex surface; a fourth lens with positive refractive power, the object side of which is a convex surface and the image side of which is a convex surface; and a fifth lens with negative refractive power, the object side of which is a concave surface and the image side of which is a concave surface.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to a fixed-focus lens. Background Technology

[0002] In recent years, optical lens technology has made rapid progress and is playing an important role in more and more fields. With the continuous upgrading and development of Internet technology, video lenses are widely used in video conferencing, online teaching, and online video shooting, and have received increasing attention from the public. As a result, the requirements for their image quality are also getting higher and higher.

[0003] However, video conferencing lenses on the market today still have many shortcomings. For example, the lens configuration of current video conferencing lenses makes it difficult to effectively correct system aberrations, resulting in poor image quality. They also generally suffer from excessively long overall length and large size, leading to high overall cost and weight. Furthermore, existing video conferencing lenses often have inadequate distortion control, resulting in significant distortion of the captured images and affecting post-processing.

[0004] Therefore, designing a fixed-focus lens with low distortion, small size, high resolution, and low cost has become an inevitable trend in market development. Summary of the Invention

[0005] This application provides a fixed-focus lens, which may include, in sequence along the optical axis from the object side to the image side: a first lens having negative optical power, wherein the object side is convex and the image side is concave; a second lens having negative optical power, wherein the object side is concave and the image side is convex; a third lens having positive optical power, wherein the object side is concave and the image side is convex; a fourth lens having positive optical power, wherein the object side is convex and the image side is convex; and a fifth lens having negative optical power, wherein the object side is concave and the image side is concave.

[0006] In one embodiment, the effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens can satisfy: -2.03≤F1 / F≤-1.95.

[0007] In one embodiment, the radius of curvature R11 of the object side of the first lens and the effective focal length F1 of the first lens can satisfy: -1.49≤R11 / F1≤-1.05.

[0008] In one embodiment, the radius of curvature R11 of the object side of the first lens, the radius of curvature R12 of the image side of the first lens, and the center thickness CT1 of the first lens on the optical axis can satisfy: 9.79≤(R11+R12) / CT1≤11.91.

[0009] In one embodiment, the effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens can satisfy: -61≤F2 / F≤-48.

[0010] In one embodiment, the combined focal length F12 of the first lens and the second lens and the total effective focal length F of the fixed-focus lens can satisfy: -2.30≤F12 / F≤-2.21.

[0011] In one embodiment, the effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens can satisfy: 1.51≤F3 / F≤1.62.

[0012] In one embodiment, the radius of curvature R22 of the image side of the second lens, the radius of curvature R31 of the object side of the third lens, the radius of curvature R32 of the image side of the third lens, and the combined focal length F23 of the second lens and the third lens can satisfy: -3.63≤(R22+R31+R32) / F23≤-2.58.

[0013] In one embodiment, the effective focal length F4 of the fourth lens and the total effective focal length F of the fixed-focus lens can satisfy: 1.00≤F4 / F≤1.05.

[0014] In one embodiment, the radius of curvature R41 of the object side of the fourth lens, the radius of curvature R42 of the image side of the fourth lens, and the center thickness CT4 of the fourth lens on the optical axis can satisfy: 0.017≤(R41+R42) / CT4≤0.160.

[0015] In one embodiment, the effective focal length F5 of the fifth lens and the total effective focal length F of the fixed-focus lens can satisfy: -1.13≤F5 / F≤-1.11.

[0016] In one embodiment, the combined focal length F45 of the fourth lens and the fifth lens and the total effective focal length F of the fixed-focus lens can satisfy: 3.89≤F45 / F≤4.80.

[0017] In one embodiment, the radius of curvature R21 of the object side of the second lens and the radius of curvature R22 of the image side of the second lens can satisfy: -0.10≤(R21-R22) / (R21+R22)≤-0.09.

[0018] In one embodiment, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, and the center distance T34 from the object side of the third lens to the image side of the fourth lens on the optical axis can satisfy: 0.90≤(CT3+CT4) / T34≤0.92.

[0019] In one embodiment, the combined focal length F345 of the third lens, the fourth lens, and the fifth lens and the total effective focal length F of the fixed-focus lens can satisfy: 1.04≤F345 / F≤1.06.

[0020] In one embodiment, the maximum value CTmax of the center thickness of each lens from the first lens to the fifth lens on the optical axis and the minimum value CTmin of the center thickness of each lens from the first lens to the fifth lens on the optical axis can satisfy: 2.69≤CTmax / CTmin≤3.33.

[0021] In one embodiment, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, and the total effective focal length F of the fixed-focus lens can satisfy: 13.88mm. -1 ≤(Vd2+Vd3) / F≤14.02mm -1 .

[0022] In one embodiment, the distance TTL from the center of the object side of the first lens to the imaging surface of the fixed-focus lens on the optical axis and the total effective focal length F of the fixed-focus lens can satisfy: 3.00≤TTL / F≤3.08.

[0023] In one embodiment, the distance BFL from the center of the image side of the fifth lens to the imaging surface of the fixed-focus lens on the optical axis and the distance TTL from the center of the object side of the first lens to the imaging surface on the optical axis can satisfy: 0.37≤BFL / TTL≤0.39.

[0024] The fixed-focus lens of this application includes first to fifth lenses arranged sequentially along the optical axis from the object side to the image side. The first lens has negative optical power, with a convex object side and a concave image side; the second lens has negative optical power, with a concave object side and a convex image side; the third lens has positive optical power, with a concave object side and a convex image side; the fourth lens has positive optical power, with a convex object side and a convex image side; and the fifth lens has negative optical power, with a concave object side and a concave image side. This arrangement of the fixed-focus lens allows the lens to achieve at least one of the following beneficial effects: low distortion, miniaturization, low cost, and high resolution. Attached Figure Description

[0025] Other features, objects, and advantages of this application will become more apparent from the following detailed description of the embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0026] Figure 1 This is a schematic diagram of the fixed-focus lens according to Embodiment 1 of this application;

[0027] Figure 2 This is a distortion curve diagram of a fixed-focus lens according to Embodiment 1 of this application;

[0028] Figure 3 This is a schematic diagram of the structure of a fixed-focus lens according to Embodiment 2 of this application;

[0029] Figure 4 This is a distortion curve diagram of a fixed-focus lens according to Embodiment 2 of this application;

[0030] Figure 5 This is a schematic diagram of the fixed-focus lens according to Embodiment 3 of this application;

[0031] Figure 6 This is a distortion curve diagram of a fixed-focus lens according to Embodiment 3 of this application;

[0032] Figure 7 This is a structural schematic diagram of a fixed-focus lens according to Embodiment 4 of this application; and

[0033] Figure 8 This is a distortion curve diagram of a fixed-focus lens according to Embodiment 4 of this application. Detailed Implementation

[0034] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0036] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0037] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging side is called the image-side surface of the lens.

[0038] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0039] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] The features, principles and other aspects of this application are described in detail below.

[0042] In an exemplary embodiment, the optical lens includes, for example, five lenses with optical power, namely a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. These five lenses are arranged sequentially along the optical axis from the object side to the image side.

[0043] In an exemplary embodiment, the first lens may have negative optical power; the second lens may have negative optical power; the third lens may have positive optical power; the fourth lens may have positive optical power; and the fifth lens may have negative optical power.

[0044] In an exemplary embodiment, the first lens may have negative optical power. The object-side surface of the first lens may be convex, and the image-side surface may be concave. The first lens has negative optical power, and its shape is a meniscus with the convex surface facing the object side. This allows it to converge as much incident light as possible into the optical system, expanding the field of view. Simultaneously, it effectively balances spherical aberration, coma, and astigmatism, improving the imaging quality of the optical system. Furthermore, it effectively corrects optical distortion, for example, reducing the absolute value of optical distortion to less than or equal to 2.20%, significantly reducing image distortion and effectively restoring the realism of the photographed object.

[0045] In an exemplary embodiment, the second lens may have negative optical power. The object-side surface of the second lens may be concave, and the image-side surface may be convex. The second lens has negative optical power, and its shape is a meniscus with the convex surface facing the image side. This effectively controls the direction of light rays, elevates the light rays, effectively balances the spherical aberration generated by the first lens, and improves image quality. Simultaneously, it effectively regulates the optical distortion of the edge field of view of the imaging system, which helps to control the distortion of the edge field of view within a reasonable range.

[0046] In an exemplary embodiment, the third lens may have positive optical power. The object-side surface of the third lens may be concave, and the image-side surface may be convex. The third lens has positive optical power and a concave-convex shape, which is beneficial for controlling the direction of light rays. By compressing the angle of the incident light rays, a smooth transition of light rays is achieved. At the same time, by introducing positive spherical aberration, the spherical aberration generated by each lens in the optical system is effectively balanced, greatly improving the imaging performance of the optical system.

[0047] In an exemplary embodiment, the third lens can be a glass spherical lens, which helps to suppress the focus drift of the lens in high and low temperature environments, and enables the lens to have high imaging quality over a wide temperature range (e.g., -20°C to 60°C).

[0048] In an exemplary embodiment, the fourth lens may have positive optical power. The object-side surface of the fourth lens may be convex, and the image-side surface may also be convex. The fourth lens has positive optical power and a convex-convex shape, which can effectively control the direction of light rays, allowing light to smoothly transition to the rear of the optical system. This helps to correct spherical aberration in the optical system and effectively reduces the influence of the fourth lens's own field curvature and coma on the optical lens, greatly improving the imaging performance of the optical system.

[0049] In an exemplary embodiment, the fifth lens may have negative optical power. The object-side surface of the fifth lens may be concave, and the image-side surface may also be concave. The fifth lens has negative optical power and a concave-concave shape, allowing for a reasonable combination of positive and negative optical power with the fourth lens. Simultaneously, the shape of the fifth lens can be appropriately configured with the shape of the third lens, thereby effectively controlling the trajectory of light after passing through the aperture, balancing spherical aberration, coma, and astigmatism generated by the optical system, and greatly improving the imaging performance of the optical system. Furthermore, it can effectively correct optical distortion, for example, making the absolute value of optical distortion less than or equal to 2.20%, greatly reducing the degree of image distortion and effectively restoring the realism of the photographed object.

[0050] In an exemplary embodiment, the fixed-focus lens according to this application may further include an aperture stop, which may be located, for example, between the second lens and the third lens. This aperture stop effectively gathers the light entering the optical system, shortens the overall length of the optical system, and reduces the maximum aperture of the optical system, thus facilitating the miniaturization of the optical lens design. It should be noted that the location of the aperture stop disclosed herein is merely an example and not a limitation; in alternative embodiments, the aperture stop may be placed in other locations as needed.

[0051] In an exemplary embodiment, the fixed-focus lens may further include a photosensitive element disposed on the imaging surface. Optionally, the photosensitive element disposed on the imaging surface may be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS).

[0052] In an exemplary embodiment, the lenses included in the fixed-focus lens may include aspherical lenses. For example, in one embodiment, the first lens, the second lens, the fourth lens, and the fifth lens may be aspherical lenses.

[0053] A fixed-focus lens according to an exemplary embodiment of this application includes a first lens to a fifth lens arranged sequentially along the optical axis from the object side to the image side. The first lens has negative optical power, a convex object side, and a concave image side; the second lens has negative optical power, a concave object side, and a convex image side; the third lens has positive optical power, a concave object side, and a convex image side; the fourth lens has positive optical power, a convex object side, and a convex image side; and the fifth lens has negative optical power, a concave object side, and a concave image side. This arrangement of the fixed-focus lens allows it to achieve at least one of the following beneficial effects: low distortion, miniaturization, low cost, and high resolution.

[0054] In an exemplary embodiment, the fixed-focus lens according to this application satisfies the following condition: -2.03 ≤ F1 / F ≤ -1.95, where F1 is the effective focal length of the first lens and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the effective focal length of the first lens to the total effective focal length of the fixed-focus lens within this range, it is beneficial to balance the spherical aberration, coma, and astigmatism generated by incident light entering the optical system, thereby improving the imaging quality of the optical system.

[0055] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -1.49 ≤ R11 / F1 ≤ -1.05, where R11 is the radius of curvature of the object-side surface of the first lens, and F1 is the effective focal length of the first lens. By controlling the ratio of the radius of curvature of the object-side surface of the first lens to the effective focal length of the first lens within this range, it is beneficial to control the shape of the lens on the object-side surface of the first lens, allowing more light from the field of view to converge into the optical system, effectively expanding the field of view of the optical system.

[0056] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 9.79 ≤ (R11 + R12) / CT1 ≤ 11.91, where R11 is the radius of curvature of the object-side surface of the first lens, R12 is the radius of curvature of the image-side surface of the first lens, and CT1 is the center thickness of the first lens on the optical axis. By controlling the ratio of the sum of the radius of curvature of the object-side surface and the radius of curvature of the image-side surface of the first lens to the center thickness of the first lens on the optical axis within this range, it is beneficial to constrain the shape of the first lens, avoid excessive curvature of the first lens, and facilitate the processing and shaping of the first lens.

[0057] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -61≤F2 / F≤-48, where F2 is the effective focal length of the second lens and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the effective focal length of the second lens to the total effective focal length of the fixed-focus lens within this range, it is beneficial to control the direction of light, elevate the light, effectively correct the spherical aberration generated by the first lens, and improve image quality.

[0058] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -2.30 ≤ F12 / F ≤ -2.21, where F12 is the combined focal length of the first lens and the second lens, and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the combined focal length of the first lens and the second lens to the total effective focal length of the fixed-focus lens within this range, it is beneficial to correct off-axis aberrations of the optical system. Simultaneously, it can effectively control the optical distortion of the edge field of view of the imaging system, helping to keep the distortion of the edge field of view within a reasonable range. For example, the absolute value of the optical distortion can be less than or equal to 2.20%, greatly reducing the degree of image distortion and effectively restoring the realism of the photographed object.

[0059] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 1.51 ≤ F3 / F ≤ 1.62, where F3 is the effective focal length of the third lens and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the effective focal length of the third lens to the total effective focal length of the fixed-focus lens within this range, it is beneficial to control the direction of light. By compressing the angle of the incident light rays from the object side of the third lens, a smooth transition of light is achieved. At the same time, by introducing positive spherical aberration, the spherical aberration generated by each lens in the optical system is effectively balanced, greatly improving the imaging performance of the optical system.

[0060] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -3.63 ≤ (R22 + R31 + R32) / F23 ≤ -2.58, where R22 is the radius of curvature of the image-side surface of the second lens, R31 is the radius of curvature of the object-side surface of the third lens, R32 is the radius of curvature of the image-side surface of the third lens, and F23 is the combined focal length of the second and third lenses. By controlling the radius of curvature of the image-side surface of the second lens, the radius of curvature of the object-side surface of the third lens, and the combined focal length of the second and third lenses to satisfy the condition -3.63 ≤ (R22 + R31 + R32) / F23 ≤ -2.58, it is beneficial for light to smoothly transition from the image-side surface of the second lens to the object-side surface of the third lens after passing through the aperture stop, thereby effectively reducing the deflection angle of peripheral light rays in the second and third lenses and improving the imaging quality of the peripheral field of view; at the same time, it can effectively enable the optical imaging system to have a larger entrance pupil diameter, ensuring maximum light transmission and improving the relative illumination of the optical system.

[0061] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 1.00 ≤ F4 / F ≤ 1.05, where F4 is the effective focal length of the fourth lens and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the effective focal length of the fourth lens to the total effective focal length of the fixed-focus lens within this range, it is beneficial to correct the spherical aberration generated by the first to third lenses of the optical system and improve the imaging quality of the optical system.

[0062] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 0.017 ≤ (R41 + R42) / CT4 ≤ 0.160, where R41 is the radius of curvature of the object-side surface of the fourth lens, R42 is the radius of curvature of the image-side surface of the fourth lens, and CT4 is the center thickness of the fourth lens on the optical axis. By controlling the ratio of the sum of the radius of curvature of the object-side surface and the radius of curvature of the image-side surface of the fourth lens to the center thickness of the fourth lens on the optical axis within this range, the direction of light can be effectively controlled, the deflection angle of the incident and outgoing light rays of the fourth lens can be reduced, the light can enter the rear of the optical system smoothly, the tolerance sensitivity of the fourth lens can be reduced, and the lens assembly yield can be improved.

[0063] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -1.13 ≤ F5 / F ≤ -1.11, where F5 is the effective focal length of the fifth lens and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the effective focal length of the fifth lens to the total effective focal length of the fixed-focus lens within this range, the direction of light can be effectively controlled, allowing the light to transition smoothly from the fifth lens to the imaging plane. This corrects various aberrations generated by the optical system, such as astigmatism, coma, and spherical aberration, greatly improving the imaging performance of the optical system. Simultaneously, it can effectively correct optical distortion, for example, making the absolute value of optical distortion less than or equal to 2.20%, significantly reducing the degree of image distortion and effectively restoring the realism of the photographed object.

[0064] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 3.89 ≤ F45 / F ≤ 4.80, where F45 is the combined focal length of the fourth and fifth lenses, and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the combined focal length of the fourth and fifth lenses to the total effective focal length of the fixed-focus lens within this range, spherical aberration of the optical system can be effectively corrected, thereby improving optical imaging performance.

[0065] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: -0.10≤(R21-R22) / (R21+R22)≤-0.09, where R21 is the radius of curvature of the object-side surface of the second lens, and R22 is the radius of curvature of the image-side surface of the second lens. By controlling the radius of curvature of the object-side surface of the second lens and the radius of curvature of the image-side surface of the second lens to satisfy the condition -0.10≤(R21-R22) / (R21+R22)≤-0.09, it is beneficial to control the shape of the second lens, effectively control the light path, elevate the light, and allow more incident light from the field of view to enter the rear of the optical system, thereby improving illumination.

[0066] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 0.90 ≤ (CT3 + CT4) / T34 ≤ 0.92, where CT3 is the center thickness of the third lens on the optical axis, CT4 is the center thickness of the fourth lens on the optical axis, and T34 is the center distance on the optical axis from the object-side surface of the third lens to the image-side surface of the fourth lens. By controlling the ratio of the sum of the center thicknesses of the third lens and the fourth lens on the optical axis to the center distance on the optical axis from the object-side surface of the third lens to the image-side surface of the fourth lens within this range, it is beneficial to correct spherical aberration and marginal aberration, thereby improving the imaging quality of the optical system. At the same time, under the premise of satisfying high resolution, by reasonably adjusting the ratio, the center distance on the optical axis from the object-side surface of the third lens to the image-side surface of the fourth lens is minimized, which is beneficial to achieving the miniaturization design of the optical system.

[0067] In an exemplary embodiment, the fixed-focus lens according to this application satisfies the following condition: 1.04 ≤ F345 / F ≤ 1.06, where F345 is the combined focal length of the third, fourth, and fifth lenses, and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the combined focal length of the third, fourth, and fifth lenses to the total effective focal length of the fixed-focus lens within this range, light rays from each field of view can smoothly transition to the rear of the optical system. This effectively balances various aberrations generated by light passing through the first and second lenses of the optical system, thereby improving the imaging quality of the optical lens.

[0068] In an exemplary embodiment, the fixed-focus lens according to this application satisfies the following condition: 2.69 ≤ CTmax / CTmin ≤ 3.33, where CTmax is the maximum value of the center thickness of each lens from the first to the fifth lens along the optical axis, and CTmin is the minimum value of the center thickness of each lens from the first to the fifth lens along the optical axis. By controlling the ratio of the maximum to the minimum value of the center thickness of each lens from the first to the fifth lens within this range, the thickness of each lens in the optical lens can be reasonably controlled, which is beneficial for stabilizing the function of each lens, minimizing changes in light trajectory under high and low temperatures, and enabling the lens to achieve heat-free operation.

[0069] In an exemplary embodiment, the fixed-focus lens according to this application satisfies the following: 13.88mm -1 ≤(Vd2+Vd3) / F≤14.02mm -1 Where Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the sum of the Abbe numbers of the second and third lenses to the total effective focal length of the fixed-focus lens within this range, chromatic aberration of the system can be effectively corrected, which is beneficial to improving the saturation of lens colors.

[0070] In an exemplary embodiment, the fixed-focus lens according to this application satisfies: 3.00 ≤ TTL / F ≤ 3.08, where TTL is the distance on the optical axis from the center of the object-side surface of the first lens to the imaging surface of the fixed-focus lens, and F is the total effective focal length of the fixed-focus lens. By controlling the ratio of the distance on the optical axis from the center of the object-side surface of the first lens to the imaging surface of the fixed-focus lens to the total effective focal length of the fixed-focus lens within this range, under a certain total effective focal length of the optical system, by controlling the distance on the optical axis from the center of the object-side surface of the first lens to the imaging surface of the optical lens, the distance on the optical axis is made smaller, which is beneficial for lens miniaturization. For example, the distance TTL from the center of the object-side surface of the first lens to the imaging surface of the optical lens can be ≤ 23mm.

[0071] In an exemplary embodiment, the fixed-focus lens according to this application satisfies the following condition: 0.37 ≤ BFL / TTL ≤ 0.39, where BFL is the distance on the optical axis from the center of the image-side surface of the fifth lens to the imaging plane of the fixed-focus lens, and TTL is the distance on the optical axis from the center of the object-side surface of the first lens to the imaging plane. By controlling the ratio of the distance on the optical axis from the center of the image-side surface of the fifth lens to the imaging plane of the fixed-focus lens to the distance on the optical axis from the center of the object-side surface of the first lens to the imaging plane within this range, given a fixed total length of the optical system, the assembly yield of the optical lens can be improved by reasonably controlling the back focal length of the optical lens, and it also helps to reserve space for the installation of optical components, thereby increasing the design flexibility of the optical lens.

[0072] In an exemplary embodiment, the fixed-focus lens of this application may, as needed, include a filter and / or protective glass disposed between the fifth lens and the imaging plane. The filter can filter light with a specific wavelength, and the protective glass can prevent damage to the image-side elements (e.g., the chip) of the fixed-focus lens.

[0073] The fixed-focus lens according to the embodiments of this application can employ multiple lens elements, such as the five elements described above. By rationally setting parameters such as the optical power, surface shape, radius of curvature, center thickness, and Abbe number of each lens, the lens can achieve at least one of the following beneficial effects: low distortion, miniaturization, low cost, and high resolution.

[0074] The fixed-focus lens according to the embodiments of this application can achieve, for example, optical distortion ≤ |-2.20%|; total optical length TTL ≤ 23mm.

[0075] However, those skilled in the art will understand that the number of lenses constituting the lens can be changed to obtain the various results and advantages described in this specification without departing from the technical solutions claimed in this application. For example, although five lenses are described as an example in the embodiments, the fixed-focus lens is not limited to including five lenses. If desired, the fixed-focus lens may also include other numbers of lenses. Specific embodiments of a fixed-focus lens applicable to the above embodiments are further described below with reference to the accompanying drawings.

[0076] Example 1

[0077] Figure 1 This is a schematic diagram of the fixed-focus lens according to Embodiment 1 of this application, as shown below. Figure 1 Describes a fixed-focus lens according to Embodiment 1 of this application.

[0078] like Figure 1As shown, the fixed-focus lens includes, in sequence along the optical axis from the object side to the image side: a first lens L1, a second lens L2, an aperture stop STO, a third lens L3, a fourth lens L4, a fifth lens L5, a filter and / or protective glass CG, and an imaging plane (IMA).

[0079] In this embodiment, the first lens L1 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens L2 has negative optical power, its object-side surface S3 is concave, and its image-side surface S4 is convex. The third lens L3 has positive optical power, its object-side surface S6 is concave, and its image-side surface S7 is convex. The fourth lens L4 has positive optical power, its object-side surface S8 is convex, and its image-side surface S9 is convex. The fifth lens L5 has negative optical power, its object-side surface S10 is concave, and its image-side surface S11 is concave.

[0080] In this embodiment, the filter and / or protective glass CG located between the fifth lens L5 and the imaging surface S14 (IMA) has an object-side surface S12 and an image-side surface S13. Light from the object passes sequentially through each surface S1 to S13 and is finally imaged on the imaging surface S14, where an image sensor chip IMA may be disposed.

[0081] Table 1 shows the radius of curvature R, thickness CT / distance, refractive index N, and Abbe number Vd of each lens in the fixed-focus lens of Example 1. Regarding "thickness CT / distance," it should be understood that the thickness CT / distance in row S1 is the center thickness of the first lens L1, the thickness CT / distance in row S2 is the air gap distance between the first lens L1 and the second lens L2, the thickness CT / distance in row S3 is the center thickness of the second lens L2, and so on.

[0082]

[0083]

[0084] Table 1

[0085] In Embodiment 1, the object-side and image-side surfaces of the first lens L1, the second lens L2, the fourth lens L4, and the fifth lens L5 are all aspherical surfaces. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0086]

[0087] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 below gives the conic coefficient k and higher-order coefficients A4, A6, A8, A11 that can be used for each aspherical mirror S1 to S4, S8 to S11 in Example 1. 10 A 12 A 14 and A 16 .

[0088] S1 2.65 3.29E-03 -1.80E-04 2.18E-05 -3.12E-06 2.98E-07 -1.54E-08 3.28E-10 S2 3.62 6.79E-03 -4.89E-04 2.46E-04 -8.79E-05 1.46E-05 -8.91E-07 -3.00E-08 S3 -7.77 -6.57E-03 9.03E-04 -5.05E-05 -4.46E-05 1.92E-05 -3.24E-06 2.03E-07 S4 0.07 2.20E-03 -7.71E-05 9.93E-05 -4.06E-05 1.00E-05 -1.24E-06 6.08E-08 S8 -17.61 3.50E-03 -5.41E-04 7.77E-05 -8.84E-06 7.06E-07 -3.40E-08 8.18E-10 S9 1.72 1.41E-03 -4.39E-04 6.95E-05 -4.34E-06 6.86E-08 2.43E-09 1.77E-10 S10 -30.01 5.82E-03 -1.08E-03 2.82E-05 1.26E-05 -1.87E-06 9.88E-08 -1.34E-09 S11 -28.40 1.26E-02 -1.54E-03 1.09E-04 -1.46E-05 3.14E-06 -3.63E-07 1.58E-08

[0089] Table 2

[0090] In this embodiment, the aperture value of the fixed-focus lens is FNO = 2.40; the optical distortion of the fixed-focus lens is ≤ |-1.94%|. Figure 2 The distortion curve of the fixed-focus lens in Example 1 is shown. According to... Figure 2 It can be seen that the fixed-focus lens given in Example 1 can achieve a low distortion effect.

[0091] Example 2

[0092] Figure 3 A schematic diagram of the fixed-focus lens according to Embodiment 2 of this application is shown below, with reference to the following. Figure 3 This application describes a fixed-focus lens according to Embodiment 2. For the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted in this embodiment and the following embodiments.

[0093] like Figure 3 As shown, the fixed-focus lens includes, in sequence along the optical axis from the object side to the image side: a first lens L1, a second lens L2, an aperture stop STO, a third lens L3, a fourth lens L4, a fifth lens L5, a filter and / or protective glass CG, and an imaging plane (IMA).

[0094] In this embodiment, the first lens L1 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens L2 has negative optical power, its object-side surface S3 is concave, and its image-side surface S4 is convex. The third lens L3 has positive optical power, its object-side surface S6 is concave, and its image-side surface S7 is convex. The fourth lens L4 has positive optical power, its object-side surface S8 is convex, and its image-side surface S9 is convex. The fifth lens L5 has negative optical power, its object-side surface S10 is concave, and its image-side surface S11 is concave.

[0095] In this embodiment, the filter and / or protective glass CG located between the fifth lens L5 and the imaging surface S14 (IMA) has an object-side surface S12 and an image-side surface S13. Light from the object passes sequentially through each surface S1 to S13 and is finally imaged on the imaging surface S14, where an image sensor chip IMA may be disposed.

[0096] Table 3 shows the radius of curvature R, thickness CT / distance, refractive index N, and Abbe number Vd of each lens in the fixed-focus lens of Example 2.

[0097]

[0098] Table 3

[0099] In this embodiment, the object-side and image-side surfaces of the first lens L1, the second lens L2, the fourth lens L4, and the fifth lens L5 are all aspherical surfaces, and the surface shape of each aspherical surface can be defined by formula (1) given in Embodiment 1 above. Table 4 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A11 of each aspherical mirror surface S1 to S4 and S8 to S11 that can be used in this embodiment. 10 A 12 A 14 and A 16 .

[0100]

[0101]

[0102] Table 4

[0103] In this embodiment, the aperture value of the fixed-focus lens is FNO = 2.40; the optical distortion of the fixed-focus lens is ≤ |-2.20%|. Figure 4 The distortion curve of the fixed-focus lens in Example 2 is shown. According to... Figure 4 It can be seen that the fixed-focus lens given in Example 2 can achieve a low distortion effect.

[0104] Example 3

[0105] Figure 5 A schematic diagram of the fixed-focus lens according to Embodiment 3 of this application is shown below, with reference to the following. Figure 5 Describes a fixed-focus lens according to Embodiment 3 of this application.

[0106] like Figure 5 As shown, the fixed-focus lens includes, in sequence along the optical axis from the object side to the image side: a first lens L1, a second lens L2, an aperture stop STO, a third lens L3, a fourth lens L4, a fifth lens L5, a filter and / or protective glass CG, and an imaging plane (IMA).

[0107] In this embodiment, the first lens L1 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens L2 has negative optical power, its object-side surface S3 is concave, and its image-side surface S4 is convex. The third lens L3 has positive optical power, its object-side surface S6 is concave, and its image-side surface S7 is convex. The fourth lens L4 has positive optical power, its object-side surface S8 is convex, and its image-side surface S9 is convex. The fifth lens L5 has negative optical power, its object-side surface S10 is concave, and its image-side surface S11 is concave.

[0108] In this embodiment, the filter and / or protective glass CG located between the fifth lens L5 and the imaging surface S14 (IMA) has an object-side surface S12 and an image-side surface S13. Light from the object passes sequentially through each surface S1 to S13 and is finally imaged on the imaging surface S14, where an image sensor chip IMA may be disposed.

[0109] Table 5 shows the radius of curvature R, thickness CT / distance, refractive index N, and Abbe number Vd of each lens in the fixed-focus lens of Example 3.

[0110]

[0111]

[0112] Table 5

[0113] In this embodiment, the object-side and image-side surfaces of the first lens L1, the second lens L2, the fourth lens L4, and the fifth lens L5 are all aspherical surfaces, and the surface shape of each aspherical surface can be defined by formula (1) given in Embodiment 1 above. Table 6 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A11 of each aspherical mirror surface S1 to S4 and S8 to S11 that can be used in this embodiment. 10 A 12 A 14 and A 16 .

[0114] S1 4.15 3.29E-03 -1.80E-04 2.18E-05 -3.12E-06 2.98E-07 -1.54E-08 3.28E-10 S2 3.08 6.79E-03 -4.89E-04 2.46E-04 -8.79E-05 1.46E-05 -8.91E-07 -3.00E-08 S3 -7.99 -6.57E-03 9.03E-04 -5.05E-05 -4.46E-05 1.92E-05 -3.24E-06 2.03E-07 S4 0.01 2.20E-03 -7.71E-05 9.93E-05 -4.06E-05 1.00E-05 -1.24E-06 6.08E-08 S8 -17.04 3.50E-03 -5.41E-04 7.77E-05 -8.84E-06 7.06E-07 -3.40E-08 8.18E-10 S9 2.01 1.41E-03 -4.39E-04 6.95E-05 -4.34E-06 6.86E-08 2.43E-09 1.77E-10 S10 -30.01 5.82E-03 -1.08E-03 2.82E-05 1.26E-05 -1.87E-06 9.88E-08 -1.34E-09 S11 -28.40 1.26E-02 -1.54E-03 1.09E-04 -1.46E-05 3.14E-06 -3.63E-07 1.58E-08

[0115] Table 6

[0116] In this embodiment, the aperture value of the fixed-focus lens is FNO = 2.40; the optical distortion of the fixed-focus lens is ≤ |-2.02%|. Figure 6 The distortion curve of the fixed-focus lens in Example 3 is shown. According to... Figure 6 It can be seen that the fixed-focus lens given in Example 3 can achieve a low distortion effect.

[0117] Example 4

[0118] Figure 7A schematic diagram of the fixed-focus lens according to Embodiment 4 of this application is shown below, with reference to the following. Figure 7 Describes a fixed-focus lens according to Embodiment 4 of this application.

[0119] like Figure 7 As shown, the fixed-focus lens includes, in sequence along the optical axis from the object side to the image side: a first lens L1, a second lens L2, an aperture stop STO, a third lens L3, a fourth lens L4, a fifth lens L5, a filter and / or protective glass CG, and an imaging plane (IMA).

[0120] In this embodiment, the first lens L1 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens L2 has negative optical power, its object-side surface S3 is concave, and its image-side surface S4 is convex. The third lens L3 has positive optical power, its object-side surface S6 is concave, and its image-side surface S7 is convex. The fourth lens L4 has positive optical power, its object-side surface S8 is convex, and its image-side surface S9 is convex. The fifth lens L5 has negative optical power, its object-side surface S10 is concave, and its image-side surface S11 is concave.

[0121] In this embodiment, the filter and / or protective glass CG located between the fifth lens L5 and the imaging surface S14 (IMA) has an object-side surface S12 and an image-side surface S13. Light from the object passes sequentially through each surface S1 to S13 and is finally imaged on the imaging surface S14, where an image sensor chip IMA may be disposed.

[0122] Table 7 shows the radius of curvature R, thickness CT / distance, refractive index N, and Abbe number Vd of each lens in the fixed-focus lens of Example 4.

[0123]

[0124] Table 7

[0125] In this embodiment, the object-side and image-side surfaces of the first lens L1, the second lens L2, the fourth lens L4, and the fifth lens L5 are all aspherical surfaces, and the surface shape of each aspherical surface can be defined by formula (1) given in Embodiment 1 above. Table 8 gives the conic coefficient k and higher-order coefficients A4, A6, A8, and A11 of each aspherical mirror surface S1 to S4 and S8 to S11 that can be used in this embodiment. 10 A 12 A 14 and A 16 .

[0126] S1 4.20 3.29E-03 -1.80E-04 2.18E-05 -3.12E-06 2.98E-07 -1.54E-08 3.28E-10 S2 3.73 6.79E-03 -4.89E-04 2.46E-04 -8.79E-05 1.46E-05 -8.91E-07 -3.00E-08 S3 -7.81 -6.57E-03 9.03E-04 -5.05E-05 -4.46E-05 1.92E-05 -3.24E-06 2.03E-07 S4 0.04 2.20E-03 -7.71E-05 9.93E-05 -4.06E-05 1.00E-05 -1.24E-06 6.08E-08 S8 -16.47 3.50E-03 -5.41E-04 7.77E-05 -8.84E-06 7.06E-07 -3.40E-08 8.18E-10 S9 1.70 1.41E-03 -4.39E-04 6.95E-05 -4.34E-06 6.86E-08 2.43E-09 1.77E-10 S10 -30.01 5.82E-03 -1.08E-03 2.82E-05 1.26E-05 -1.87E-06 9.88E-08 -1.34E-09 S11 -28.40 1.26E-02 -1.54E-03 1.09E-04 -1.46E-05 3.14E-06 -3.63E-07 1.58E-08

[0127] Table 8

[0128] In this embodiment, the aperture value of the fixed-focus lens is FNO = 2.40; the optical distortion of the fixed-focus lens is ≤ |-1.99%|. Figure 8 The distortion curve of the fixed-focus lens in Example 4 is shown. According to... Figure 8 It can be seen that the fixed-focus lens given in Example 4 can achieve a low distortion effect.

[0129] In summary, Examples 1 to 4 satisfy the relationships shown in Table 9 below.

[0130]

[0131]

[0132] Table 9

[0133] This application also provides an electronic device that may include a fixed-focus lens according to the above embodiments of this application and an imaging element for converting the optical image formed by the fixed-focus lens into an electrical signal.

[0134] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A fixed-focus lens, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: The first lens with negative optical power has a convex object side and a concave image side. A second lens with negative optical power has a concave object side and a convex image side. A third lens with positive optical power has a concave object side and a convex image side. A fourth lens with positive optical power, having a convex object-side surface and a convex image-side surface; and A fifth lens with negative optical power has a concave object-side surface and a concave image-side surface; among which, The maximum value CTmax of the center thickness of each lens from the first lens to the fifth lens on the optical axis and the minimum value CTmin of the center thickness of each lens from the first lens to the fifth lens on the optical axis satisfy the following condition: 2.79≤CTmax / CTmin≤3.

24.

2. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: -2.03≤F1 / F≤-1.

95.

3. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R11 of the object side of the first lens and the effective focal length F1 of the first lens satisfy: -1.42≤R11 / F1≤-1.

11.

4. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R11 of the object side of the first lens, the radius of curvature R12 of the image side of the first lens, and the center thickness CT1 of the first lens on the optical axis satisfy: 10.10≤(R11+R12) / CT1≤11.

61.

5. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: -58.53≤F2 / F≤-50.

01.

6. The fixed-focus lens according to claim 1, characterized in that, The combined focal length F12 of the first lens and the second lens satisfies the following condition with the total effective focal length F of the fixed-focus lens: -2.30≤F12 / F≤-2.

21.

7. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: 1.51≤F3 / F≤1.

62.

8. The fixed-focus lens according to claim 1, characterized in that, The curvature radius R22 of the image side of the second lens, the curvature radius R31 of the object side of the third lens, the curvature radius R32 of the image side of the third lens, and the combined focal length F23 of the second lens and the third lens satisfy: -3.48≤(R22+R31+R32) / F23≤-2.

73.

9. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F4 of the fourth lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: 1.00≤F4 / F≤1.

05.

10. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R41 of the object side of the fourth lens, the radius of curvature R42 of the image side of the fourth lens, and the center thickness CT4 of the fourth lens on the optical axis satisfy: 0.017≤(R41+R42) / CT4≤0.

160.

11. The fixed-focus lens according to claim 1, characterized in that, The effective focal length F5 of the fifth lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: -1.13≤F5 / F≤-1.

11.

12. The fixed-focus lens according to claim 1, characterized in that, The combined focal length F45 of the fourth lens and the fifth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: 4.03≤F45 / F≤4.

66.

13. The fixed-focus lens according to claim 1, characterized in that, The radius of curvature R21 of the object side of the second lens and the radius of curvature R22 of the image side of the second lens satisfy: -0.10≤(R21-R22) / (R21+R22)≤-0.

09.

14. The fixed-focus lens according to claim 1, characterized in that, The center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, and the center distance T34 from the object side of the third lens to the image side of the fourth lens on the optical axis satisfy the following condition: 0.90≤(CT3+CT4) / T34≤0.

92.

15. The fixed-focus lens according to claim 1, characterized in that, The combined focal length F345 of the third lens, the fourth lens, and the fifth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: 1.04 ≤ F345 / F ≤ 1.

06.

16. The fixed-focus lens according to claim 1, characterized in that, The Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, and the total effective focal length F of the fixed-focus lens satisfy the following condition: 13.88mm. -1 ≤(Vd2+Vd3) / F≤14.02mm -1 .

17. The fixed-focus lens according to claim 1, characterized in that, The distance TTL from the center of the object side of the first lens to the imaging plane of the fixed-focus lens on the optical axis satisfies the following condition: 3.00≤TTL / F≤3.

08.

18. The fixed-focus lens according to claim 1, characterized in that, The distance BFL from the center of the image side of the fifth lens to the imaging surface of the fixed-focus lens on the optical axis and the distance TTL from the center of the object side of the first lens to the imaging surface on the optical axis satisfy the following condition: 0.37 ≤ BFL / TTL ≤ 0.39.

Images