Small-caliber optical lens

Abstract

The invention relates to a small-caliber optical lens, and aims to realize the design targets of high imaging quality, ultra-wide field of view and miniaturization by optimizing parameters such as focal power, curved surface shape, thickness and the like of a lens. The lens is composed of four plastic lenses which are a first lens (P1) with negative focal power, a second lens (P2) with positive focal power, a third lens (P3) with positive focal power and a fourth lens (P4) with positive focal power in sequence from an object side to an imaging surface along an optical axis. The design meets various optical parameter conditions, for example, the focal length ratio (-2 < f1 / f2 <-0.5, 0.2 < f3 / f4 < 1.2), the relation between the effective focal length and the focal length of each lens (for example,-3.004 < f1 / f <-2.554) and the like. In addition, the four lenses are all XY polynomial curved surfaces, and the mechanical structure and the optical performance are optimized. The lens adopts the design of four plastic lenses, is compact in structure, is suitable for miniaturized equipment, can capture more light rays, is suitable for low-light conditions, and can be used for mobile phone cameras, security monitoring equipment and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and particularly to a small-aperture optical lens. Background Art

[0002] With the continuous development of optical imaging technology, small-aperture optical lenses are increasingly widely used in various devices, such as mobile phone cameras, security monitoring devices, etc. However, the existing small-aperture optical lenses still have some deficiencies in terms of imaging quality, optical power distribution, field of view angle, etc., and cannot meet the growing demands for high resolution, large field of view angle, etc. Therefore, a new type of small-aperture optical lens is needed to improve the imaging quality and optical performance. Summary of the Invention

[0003] The present invention aims to provide a small-aperture optical lens, and by reasonably designing parameters such as the optical power, surface shape, and thickness of the lenses, good imaging effects and optical performance can be achieved.

[0004] The present invention adopts the following technical solutions:

[0005] A small-aperture optical lens is composed of four plastic lenses, and is characterized in that, along the optical axis from the object side to the imaging surface, it successively includes:

[0006] A first lens (P1) with negative optical power, whose object side is convex and image side is concave;

[0007] A second lens (P2) with positive optical power, whose object side is concave and image side is convex;

[0008] A third lens (P3) with positive optical power, whose object side is convex and image side is concave;

[0009] A fourth lens (P4) with positive optical power, whose object side is convex and image side is concave;

[0010] Wherein, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -2 < f1 / f2 < -0.5; the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.2 < f3 / f4 < 1.2.

[0011] Furthermore, the four lenses of the small-aperture optical lens are all XY polynomial surfaces.

[0012] Furthermore, the effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 < f1 / f < -2.554.

[0013] Furthermore, the effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 < f2 / f < 2.3.

[0014] Furthermore, the effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 < f3 / f < 3.435.

[0015] Furthermore, the effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 < f4 / f < 4.360.

[0016] Furthermore, the image-space F-number of the small-aperture optical lens satisfies: 2.3 < F < 2.7.

[0017] Furthermore, the angle CA between the chief ray of the maximum field of view of the small-aperture optical lens and the optical axis satisfies: CA < 36°.

[0018] Furthermore, the thickness CT1 of the first lens of the small-aperture optical lens on the optical axis and the thickness CT2 of the second lens on the optical axis satisfy: CT1 / CT2 < 1.06.

[0019] Furthermore, the effective focal length f of the small-aperture optical lens and the distance TTL from the object side surface of the first lens of the small-aperture optical lens to the imaging surface on the optical axis satisfy: 0.15 < f / TTL < 0.21.

[0020] Furthermore, the maximum horizontal field of view HFOV of the small-aperture optical lens satisfies: HFOV > 120°.

[0021] Furthermore, the ratio of the maximum horizontal field of view HFOV to the maximum vertical field of view VFOV of the small-aperture optical lens satisfies: HFOV / VFOV > 3.7.

[0022] The small-aperture optical lens of the present invention realizes the design goals of high imaging quality, ultra-wide field of view and miniaturization by optimizing the optical power, shape and arrangement order of the lenses. Compared with the prior art, the present invention has the following advantages:

[0023] 1. Adopting a four-piece plastic lens design, the structure is compact and suitable for miniaturized devices;

[0024] 2. By reasonable focal length ratio and optical parameter optimization, an ultra-wide field of view is achieved;

[0025] 3. The image-space F-number is small, which can capture more light and is suitable for low-light conditions;

[0026] 4. Optimized field of view and distortion control ensure imaging quality. Description of the Drawings

[0027] Figure 1Schematic diagram of the first embodiment of the present invention;

[0028] Figure 2 Distortion diagram of the first embodiment of the present invention;

[0029] Figure 3 Astigmatism curve graph of the first embodiment of the present invention; Detailed implementation manners

[0030] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application and do not limit the scope of the present 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.

[0031] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0032] In the drawings, for the sake of convenience of illustration, the thickness, dimensions and shapes of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0033] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface 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 position of the concave surface 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 object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0034] It should also be understood that the terms "comprise", "comprising", "have", "include" and / or "including", 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. In addition, when an expression such as "at least one of..." appears after the list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0035] Unless otherwise defined, 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 belongs. It should also be understood that terms (such as those defined in a commonly used dictionary) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0036] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The following will detail this application with reference to the drawings and in combination with the embodiments.

[0037] The optical lens provided by the example of the present invention, a small-aperture optical lens, is composed of four plastic lenses. It is characterized in that, along the optical axis from the object side to the imaging surface, it successively includes:

[0038] A first lens (P1) with negative optical power, whose object side is convex and image side is concave;

[0039] A second lens (P2) with positive optical power, whose object side is concave and image side is convex;

[0040] A third lens (P3) with positive optical power, whose object side is convex and image side is concave;

[0041] A fourth lens (P4) with positive optical power, whose object side is convex and image side is concave;

[0042] Wherein, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -2 < f1 / f2 < -0.5; the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.2 < f3 / f4 < 1.2.

[0043] In some embodiments, the four lenses of the small-aperture optical lens are all XY polynomial surfaces. Meeting the above conditions can effectively optimize the optical performance and reduce aberration.

[0044] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 < f1 / f < -2.554. Meeting the above conditions can allow more incident light to enter the system and improve the imaging quality.

[0045] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 < f2 / f < 2.3. Meeting the above conditions is beneficial to reducing the difficulty of distortion correction.

[0046] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 < f3 / f < 3.435. Meeting the above conditions is beneficial to increasing the degree of light divergence and improving the imaging quality of the lens.

[0047] In some embodiments, the effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 < f4 / f < 4.360. Meeting the above conditions can effectively reduce the difficulty of correcting field curvature and distortion and improve the overall resolution.

[0048] In some embodiments, the image-side F-number of the small-aperture optical lens satisfies: 2.3 < F < 2.7. Meeting the above conditions can capture more light and make it suitable for low-light conditions.

[0049] In some embodiments, the angle CA between the chief ray of the maximum field of view of the small-aperture optical lens and the optical axis satisfies: CA < 36°. Meeting the above conditions can optimize the optical design and reduce distortion.

[0050] In some embodiments, the thickness CT1 of the first lens of the small-aperture optical lens on the optical axis and the thickness CT2 of the second lens on the optical axis satisfy: CT1 / CT2 < 1.06. Meeting the above conditions can optimize the mechanical structure and optical performance.

[0051] In some embodiments, the effective focal length f of the small-aperture optical lens and the distance TTL from the object side surface of the first lens of the small-aperture optical lens to the imaging surface on the optical axis satisfy: 0.15 < f / TTL < 0.21. Meeting the above conditions can effectively limit the lens length and is beneficial to realizing the miniaturization of the optical lens.

[0052] In some embodiments, the maximum horizontal field of view angle HFOV of the small-aperture optical lens satisfies: HFOV > 120°. Meeting the above conditions can achieve an ultra-wide-angle field of view.

[0053] In some embodiments, the ratio of the maximum horizontal field of view angle HFOV to the maximum vertical field of view angle VFOV of the small-aperture optical lens satisfies: HFOV / VFOV > 3.7. Meeting the above conditions can further optimize the optical design and improve the imaging quality.

[0054] Example 1

[0055] As a specific embodiment of the present invention, the parameters of a small-aperture optical lens are shown in Table 1 below:

[0056] Table 1 Structural parameter table of a small-aperture optical lens

[0057]

[0058]

[0059] Table 2 Surface coefficient table of a small-aperture optical lens

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] In the description of this specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0068] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A small-aperture optical lens, consisting of four plastic lenses, characterized in that: Along the optical axis from the object side to the imaging surface, it includes: a first lens (P1) having negative optical power, whose object-side surface is convex and whose image-side surface is concave; a second lens (P2) having positive power, whose object-side surface is concave and whose image-side surface is convex; a third lens (P3) having positive power, with a convex object-side surface and a concave image-side surface; a fourth lens (P4) having positive refractive power, whose object-side surface is convex and whose image-side surface is concave; The focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -2<f1 / f2<-0.5; the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.2<f3 / f4<1.

2.

2. A small-aperture optical lens according to claim 1, characterized in that: The four lenses of the small-aperture optical lens are all XY polynomial surfaces.

3. A small-aperture optical lens according to claim 1, characterized in that: The effective focal length f of the small-aperture optical lens and the focal length f1 of the first lens satisfy: -3.004 <f1 / f<-2.554。 4. A small-aperture optical lens according to claim 1, characterized in that: The effective focal length f of the small-aperture optical lens and the focal length f2 of the second lens satisfy: 1.587 <f2 / f<2.3。 5. The small-aperture optical lens according to claim 1, characterized in that: The effective focal length f of the small-aperture optical lens and the focal length f3 of the third lens satisfy: 3.031 <f3 / f<3.435。 6. The small-aperture optical lens according to claim 1, characterized in that: The effective focal length f of the small-aperture optical lens and the focal length f4 of the fourth lens satisfy: 4.068 <f4 / f<4.360。 7. The small-aperture optical lens according to claim 1, characterized in that: The image-side F number of the small-aperture optical lens satisfies: 2.3<F<2.

7.

8. The small-aperture optical lens according to claim 1, characterized in that: The angle CA between the principal ray of the maximum field of view of the small-aperture optical lens and the optical axis satisfies: CA<36°.

9. The small-aperture optical lens according to claim 1, characterized in that: The thickness CT1 of the first lens of the small-aperture optical lens on the optical axis and the thickness CT2 of the second lens on the optical axis satisfy: CT1 / CT2<1.

06.

10. The small-aperture optical lens according to claim 1, characterized in that: The effective focal length f of the small-aperture optical lens and the distance TTL from the object side of the first lens of the small-aperture optical lens to the imaging surface on the optical axis satisfy: 0.15<f / TTL<0.

21.

11. The small-aperture optical lens according to claim 1, characterized in that: The maximum lateral field of view HFOV of the small-aperture optical lens satisfies: HFOV>120°.

12. The small-aperture optical lens according to claim 1, characterized in that: The ratio of the maximum transverse field of view HFOV to the maximum longitudinal field of view VFOV of the small-aperture optical lens satisfies: HFOV / VFOV>3.7.

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