CN114296223B - Optical Lenses and Imaging Equipment - Google Patents

Abstract

The invention discloses an optical lens and imaging equipment, the optical lens includes from the object side to the imaging surface along the optical axis in turn: a diaphragm; the lens comprises a first lens with positive focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; a second lens having a positive optical power, the second lens having a concave object-side surface; the image side surface of the second lens is a convex surface; a third lens having a positive optical power, an object side surface of the third lens being convex at a paraxial region and having at least one inflection point, an image side surface of the third lens being concave at a paraxial region and having at least one inflection point. The optical lens has the advantage of small volume.

Description

Optical Lenses and Imaging Equipment

technical field

The present invention relates to the technical field of imaging lenses, in particular to an optical lens and an imaging device.

Background technique

In this era of rapid technological development, technology has been integrated into every household, and electronic products, such as mobile phones, computers, etc., are a branch of technological products, even more so. These electronic products provide many conveniences in people's daily life, such as taking pictures, sharing interesting videos with others, interactive videos, etc. This series of functions are captured by optical lenses and connected with other technologies. of. With the continuous improvement of people's living standards, optical lenses with more powerful performance and smaller structure are increasingly required.

At present, with the rapid development of electronic information technology, portable electronic devices such as mobile phones, notebooks, and tablets are developing in the direction of full-screen, ultra-thin, and high-definition. Especially now, many workers are working on the go or on business trips, making portable notebooks and tablets an indispensable part of their work. Although there are some "ultra-thin" electronic products on the market, they are still not thin and light enough. One of the reasons for this is that the optical lens is still not small enough.

SUMMARY OF THE INVENTION

Therefore, the purpose of the present invention is to provide an optical lens and an imaging device, which have the advantage of small size.

The embodiments of the present invention implement the above-mentioned objects through the following technical solutions.

In a first aspect, the present invention provides an optical lens, comprising in sequence from the object side to the imaging surface along the optical axis: a diaphragm; a first lens with positive refractive power, the object side of the first lens is a convex surface, the The image side of the first lens is concave; the second lens with positive refractive power, the object side of the second lens is concave; the image side of the second lens is convex; the third lens with positive refractive power, so The object side of the third lens is convex at the near optical axis and has at least one inflection point, and the image side of the third lens is concave at the near optical axis and has at least one inflection point; wherein, the first The first lens, the second lens and the third lens are all aspherical lenses; the optical lens satisfies the following conditional formula: 0.5<CT1/AC12<1.0; wherein, AC12 indicates that the first lens and the second lens are in the light On-axis air spacing, CT1 represents the central thickness of the first lens.

In a second aspect, the present invention provides an imaging device, comprising an imaging element and the optical lens provided in the first aspect, where the imaging element is used to convert an optical image formed by the optical lens into an electrical signal.

Compared with the prior art, the optical lens provided by the present invention, through the reasonable collocation of three lenses with specific focal power and shape, enables the optical lens to meet the requirements of current people on the optical lens structure under the premise of sufficient imaging capability. Small needs.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a schematic structural diagram of an optical lens according to a first embodiment of the present invention;

2 is a field curvature diagram of the optical lens according to the first embodiment of the present invention;

3 is a distortion curve diagram of the optical lens according to the first embodiment of the present invention;

4 is a graph of on-axis point spherical aberration chromatic aberration of the optical lens according to the first embodiment of the present invention;

5 is a vertical-axis chromatic aberration curve diagram of the optical lens according to the first embodiment of the present invention;

6 is a schematic structural diagram of an optical lens according to a second embodiment of the present invention;

7 is a field curvature diagram of an optical lens according to a second embodiment of the present invention;

8 is a distortion curve diagram of an optical lens according to a second embodiment of the present invention;

9 is a graph of on-axis point spherical aberration chromatic aberration of the optical lens according to the second embodiment of the present invention;

10 is a vertical-axis chromatic aberration curve diagram of the optical lens according to the second embodiment of the present invention;

11 is a schematic structural diagram of an optical lens according to a third embodiment of the present invention;

12 is a field curvature diagram of an optical lens according to a third embodiment of the present invention;

13 is a distortion curve diagram of an optical lens according to a third embodiment of the present invention;

14 is a graph of on-axis spherical aberration and chromatic aberration of the optical lens according to the third embodiment of the present invention;

15 is a vertical-axis chromatic aberration curve diagram of an optical lens according to a third embodiment of the present invention;

FIG. 16 is a schematic structural diagram of an imaging device according to a fourth embodiment of the present invention.

Detailed ways

In order to make the objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the invention are presented in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. Throughout the specification, the same reference numerals refer to the same elements.

The present invention provides an optical lens, which includes: a diaphragm, a first lens, a second lens, a third lens and a filter in sequence from the object side to the imaging plane along the optical axis.

Wherein, the first lens has positive refractive power, the object side of the first lens is convex, and the image side of the first lens is concave;

The second lens has positive refractive power, the object side of the second lens is concave, and the image side of the second lens is convex;

The third lens has positive refractive power, the object side of the third lens is convex at the near optical axis and has at least one inflection point, and the image side of the third lens is concave and has at least one inflection point at the near optical axis;

As an embodiment, the optical lens satisfies the conditional formula:

0.5<CT1/AC12<1.0; (1)

Among them, AC12 represents the air distance between the first lens and the second lens on the optical axis, and CT1 represents the central thickness of the first lens.

For conditional formula (1), when CT1/AC12<1.0, the distance between the first lens and the second lens can be reasonably controlled, and the total optical length of the system can be effectively reduced; when 0.5<CT1/AC12, the total optical length can be shortened within the It can still meet the imaging requirements and can effectively improve the imaging capability.

As an embodiment, the optical lens satisfies the following conditional formula:

0.6<f/TTL<0.75; (2)

Wherein, TTL represents the total optical length of the optical lens, and f represents the effective focal length of the optical lens.

For conditional formula (2), when 0.6<f/TTL, the maximum imaging circle of the optical lens can meet the current market demand; when f/TTL<0.75, the total optical length of the optical lens can be reasonably controlled and shortened The overall mechanical length of the lens, so as to achieve ultra-thin effect.

As an embodiment, the optical lens satisfies the following conditional formula:

0.2<(1/f3-1/f2)/(1/f)<1.5; (3)

Wherein, f3 represents the effective focal length of the third lens, f2 represents the effective focal length of the second lens, and f represents the effective focal length of the optical lens.

When the conditional formula (3) is satisfied, the decentering sensitivity of the third lens can be distributed to the second lens, which is beneficial to improve the optical performance; at the same time, the aperture of the third lens is relatively small, so that the compact structure can be achieved under the premise of meeting the imaging requirements.

As an embodiment, the optical lens satisfies the following conditional formula:

1<D/AC12<3; (4)

Wherein, D represents the diaphragm diameter of the optical lens, and AC12 represents the air distance between the first lens and the second lens on the optical axis.

When the conditional formula (4) is satisfied, by reasonably controlling the ratio of the aperture of the clear hole to the gap between the first lens and the second lens, the loss of light during transmission between the lenses can be reduced, and a sufficient amount of light can be transmitted to the next lens. , so that the optical lens can obtain a clearer and brighter image even in a dim environment, meeting the needs of customers.

As an embodiment, the optical lens satisfies the following conditional formula:

-2<f/R22<0; (5)

Wherein, f represents the effective focal length of the optical lens, and R22 represents the curvature radius of the image side surface of the second lens.

For condition (5), when f/R22<0, the curvature of the second lens can be made smaller under the condition of satisfying the imaging requirements, which is beneficial to forming; when -2<f/R22, by reasonably controlling the first lens The curvature of the two lenses can effectively improve the aberration.

As an embodiment, the optical lens satisfies the following conditional formula:

0<R11/R12<1; (6)

Wherein, R11 represents the curvature radius of the object side surface of the first lens, and R12 represents the curvature radius of the image side surface of the first lens.

When the condition (6) is satisfied, the exit angle of the light passing through the first lens can be well controlled to ensure the image height, while reducing the lens gap with the second lens, effectively reducing the total optical length of the lens, and making it more structured. Small.

As an embodiment, the optical lens satisfies the following conditional formula:

0<(Φ31-Φ21)/(Φ32+Φ22)<1; (7)

Among them, Φ31 represents the optical power of the object side of the third lens, Φ32 represents the optical power of the image side of the third lens, Φ21 represents the optical power of the object side of the second lens, and Φ22 represents the image side of the second lens. optical power.

For conditional formula (7), when (Φ31-Φ21)/(Φ32+Φ22)<1, the total length of the optical lens can be better controlled to achieve ultra-thin characteristics; when 0<(Φ31-Φ21)/ (Φ32+Φ22), the light exit angle can be well controlled and gathered, which can effectively improve the aberration and improve the imaging quality.

As an embodiment, the optical lens satisfies the following conditional formula:

1.2<CT2/ET2<2; (8)

Among them, ET2 represents the edge thickness of the second lens, and CT2 represents the center thickness of the second lens.

When the conditional expression (8) is satisfied, on the one hand, the total optical length of the optical lens can be coordinated to achieve ultra-thin characteristics; on the other hand, the thickness ratio of the second lens can be reasonably controlled to improve the optical performance and imaging quality.

As an embodiment, the first lens, the second lens, and the third lens are all aspherical lenses. The use of aspherical lenses can effectively reduce the number of lenses, correct aberrations, and under the premise of ensuring optical performance, the structure is more compact.

The present invention will be further described below with a plurality of embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different. For details, please refer to the parameter table of each embodiment. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not only limited by the following examples, and any other changes, substitutions, combinations or simplifications that do not deviate from the innovations of the present invention, All should be regarded as equivalent replacement modes, and all are included in the protection scope of the present invention.

In each embodiment of the present invention, when the lens adopts an aspheric lens, the surface shape of the aspheric lens satisfies the following equation:

Among them, z is the distance vector height of the aspheric surface from the vertex of the aspheric surface when the height is h along the optical axis, c is the paraxial curvature of the surface, k is the conic coefficient conic, and A _2i is the aspheric surface of the 2i order type coefficient.

first embodiment

Please refer to FIG. 1 , which is a schematic structural diagram of an optical lens 100 provided by a first embodiment of the present invention. The optical lens 100 sequentially includes from the object side to the imaging surface S9 along the near optical axis direction: a diaphragm ST, a first lens L1 , the second lens L2, the third lens L3, and the filter G1.

The first lens L1 is a plastic aspherical lens with positive refractive power, the object side S1 of the first lens is convex, and the image side S2 of the first lens is concave;

The second lens L2 is a plastic aspherical lens with positive refractive power, the object side S3 of the second lens is concave, and the image side S4 of the second lens is convex;

The third lens L3 is a plastic aspherical lens with positive refractive power, the object side S5 of the third lens is convex at the near optical axis and has at least one inflection point, and the image side S6 of the third lens is at the near optical axis. is concave and has at least one inflection point;

The object side of the filter G1 is S7, and the image side is S8.

Specifically, the design parameters of the optical lens 100 provided in this embodiment are shown in Table 1, where R represents the radius of curvature (unit: mm), d represents the optical surface distance (unit: mm), and n _d represents the d-line refraction of the material rate, V _d represents the Abbe number of the material.

Table 1

Table 2 shows the surface shape coefficients of each aspherical surface of the optical lens 100 in this embodiment.

Table 2

In this example, the graphs of the field curvature, distortion, on-axis point spherical aberration and vertical-axis chromatic aberration of the optical lens 100 are shown in FIG. 2 , FIG. 3 , FIG. 4 and FIG. 5 , respectively. The curvature is within ±0.1mm, the distortion is within 2%, the point spherical aberration on the axis is within ±0.04mm, and the vertical axis chromatic aberration is within ±5μm, indicating that the 100-degree field curvature, distortion and chromatic aberration of the optical lens are well corrected.

Second Embodiment

Please refer to FIG. 6 for a schematic structural diagram of the optical lens 200 provided in this embodiment. The structure of the optical lens 200 in this embodiment is not much different from that of the optical lens 100 in the first embodiment.

The relevant parameters of each lens in the optical lens 200 provided in this embodiment are shown in Table 3.

table 3

Table 4 shows the surface shape coefficients of each aspherical surface of the optical lens 200 in this embodiment.

Table 4

In this example, the graphs of the field curvature, distortion, on-axis point spherical aberration and vertical-axis chromatic aberration of the optical lens 200 are shown in FIG. 7 , FIG. 8 , FIG. 9 and FIG. 10 respectively. It can be seen from the figures that the field The curvature is within ±0.1mm, the distortion is within 2%, the point spherical aberration on the axis is within ±0.045mm, and the vertical axis chromatic aberration is within ±2.5μm, indicating that the optical lens 200 field curvature, distortion and chromatic aberration have been well corrected.

Third Embodiment

Please refer to FIG. 11 for a schematic structural diagram of the optical lens 300 provided in this embodiment. The structure of the optical lens 300 in this embodiment is not much different from the structure of the optical lens 100 in the first embodiment.

The relevant parameters of each lens in the optical lens 300 provided in this embodiment are shown in Table 5.

table 5

Table 6 shows the surface shape coefficients of each aspherical surface of the optical lens 300 in this embodiment.

Table 6

In this example, the graphs of the field curvature, distortion, on-axis point spherical aberration and vertical-axis chromatic aberration of the optical lens 300 are shown in FIG. 12 , FIG. 13 , FIG. 14 and FIG. 15 respectively. The curvature is within ±0.1mm, the distortion is within 2%, the point spherical aberration on the axis is within ±0.04mm, and the vertical axis chromatic aberration is within ±2.5μm, indicating that the 300-degree field curvature, distortion and chromatic aberration of the optical lens have been well corrected.

Table 7 shows the optical characteristics corresponding to the above three embodiments, mainly including the effective focal length f of the optical lens, the total optical length TTL, and the values corresponding to each of the above conditional expressions.

Table 7

To sum up, the optical lenses provided by the embodiments of the present invention have the following advantages:

(1) The use of three ultra-thin lenses and a reasonable and compact combination of three lenses make the optical lens have the characteristics of small size and small total optical length (TTL<1.3mm), which can well meet the current market demand for ultra-thin electronic products. structural needs.

(2) Three plastic aspherical lenses with specific optical power are used, and through the combination of specific surface types, the optical lens has sufficient imaging capabilities to meet the current lens development trend.

(3) Compared with other ultra-thin lenses, the structure of the present invention is more compact and small under the condition of satisfying a certain imaging capability, which provides a great development space for the research and development of ultra-thin electronic products, and also greatly reduces the manufacturing cost. The cost is more conducive to the promotion of the market.

Fourth Embodiment

Referring to FIG. 16 , an imaging device 400 according to a fourth embodiment of the present invention is shown. The imaging device 400 may include an imaging element 410 and an optical lens (eg, the optical lens 100 ) in any of the above-mentioned embodiments. The imaging element 410 may be a CMOS (Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor) image sensor, or may be a CCD (Charge Coupled Device, charge coupled device) image sensor.

The imaging device 400 can be a smart phone, a tablet computer, a monitoring device, or any other electronic device in which the optical lens is mounted.

The imaging device 400 provided in this embodiment includes the optical lens 100. Since the optical lens 100 has the advantage of small volume, the imaging device 400 with the optical lens 100 also has the advantage of small volume.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as limiting the scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims (8)

1. an optical lens, it is characterized in that, a total of three lenses, along the optical axis from the object side to the imaging plane, sequentially include: aperture; a first lens with positive refractive power, the object side of the first lens is convex, and the image side of the first lens is concave; The second lens with positive refractive power, the object side of the second lens is concave; the image side of the second lens is convex; A third lens having positive refractive power, the object side of the third lens is convex at the near optical axis and has at least one inflection point, and the image side of the third lens is concave at the near optical axis and has at least one inflection point. an inflection point; Wherein, the first lens, the second lens and the third lens are all aspherical lenses; the optical lens satisfies the following conditional formula: 0.5<CT1/AC12<1.0; 0<(Φ31-Φ21)/(Φ32+Φ22)<1; Among them, AC12 represents the air distance between the first lens and the second lens on the optical axis, CT1 represents the central thickness of the first lens, Φ31 represents the optical power of the object side of the third lens, Φ32 represents the power of the image side of the third lens, Φ21 represents the power of the object side of the second lens, and Φ22 represents the power of the image side of the second lens. 2. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: 0.6<f/TTL<0.75; Wherein, TTL represents the total optical length of the optical lens, and f represents the effective focal length of the optical lens. 3. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: 0.2<(1/f3-1/f2)/(1/f)<1.5; Wherein, f3 represents the effective focal length of the third lens, f2 represents the effective focal length of the second lens, and f represents the effective focal length of the optical lens. 4. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: 1<D/AC12<3; Wherein, D represents the diaphragm diameter of the optical lens, and AC12 represents the air distance between the first lens and the second lens on the optical axis. 5. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: -2<f/R22<0; Wherein, f represents the effective focal length of the optical lens, and R22 represents the curvature radius of the image side surface of the second lens. 6. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: 0<R11/R12<1; Wherein, R11 represents the curvature radius of the object side surface of the first lens, and R12 represents the curvature radius of the image side surface of the first lens. 7. The optical lens according to claim 1, wherein the optical lens satisfies the following conditional formula: 1.2<CT2/ET2<2; Wherein, ET2 represents the edge thickness of the second lens, and CT2 represents the center thickness of the second lens. 8. An imaging device, comprising the optical lens and an imaging element according to any one of claims 1-7, wherein the imaging element is used to convert an optical image formed by the optical lens into an electrical signal.

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