CN109212725B

CN109212725B - Wide-angle lens

Info

Publication number: CN109212725B
Application number: CN201811342771.3A
Authority: CN
Inventors: 史柴源
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2018-11-09
Filing date: 2018-11-09
Publication date: 2020-11-24
Anticipated expiration: 2038-11-09
Also published as: CN109212725A

Abstract

The invention provides a wide-angle lens, which comprises a first lens, a second lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens, wherein the first lens, the second lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens are sequentially arranged from an object side to an image side, the light incoming surface of the first lens is a convex surface, and the light outgoing surface of the first lens is a concave surface; the first lens and the third lens are made of glass materials, and light rays at the object side are transmitted to the image side for imaging through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens in sequence. The wide-angle lens provided by the invention can keep the original imaging effect when the temperature changes, greatly improves the environmental adaptability of the wide-angle lens, can image clearly in the environment of-20-60 ℃, and has high resolution at normal temperature.

Description

Wide-angle lens

Technical Field

The invention relates to the field of optical imaging, in particular to a wide-angle lens.

Background

The wide-angle lens is widely applied to photographing equipment such as mobile phones and single lens reflex cameras, is deeply loved by broad photographers, and has increasingly large requirements on small-size and low-cost lenses along with the continuous improvement of application requirements. The wide-angle lens is sensitive to the environment, in the prior art, the wide-angle lens capable of clearly imaging in a high-temperature or low-temperature environment is a glass lens, so that the cost is high, and the number of the lenses is large, thereby being not beneficial to miniaturization; the full plastic lens has low cost, but has poor environmental adaptability, and the imaging quality in a higher temperature or low temperature environment cannot meet the use requirement; the combination of the plastic lens and the glass lens can improve the environmental adaptability and ensure lower production cost, but the environmental adaptability of the existing combined lens is still not improved as the plastic lens and the glass lens are simply combined.

Disclosure of Invention

The invention mainly aims to provide a wide-angle lens, aiming at solving the problem that the combined wide-angle lens of a plastic lens and a glass lens is poor in environmental adaptability.

In order to achieve the above object, the present invention provides a wide-angle lens, which includes a first lens having a convex light-incident surface and a concave light-emitting surface, a second lens having a convex light-incident surface and a concave light-emitting surface, a third lens having a biconvex structure, a diaphragm, a fourth lens having a biconvex structure, a fifth lens having a biconcave structure, and a sixth lens having a biconvex structure, sequentially arranged from an object side to an image side; the first lens and the third lens are made of glass materials, and light rays at the object side are transmitted to the image side for imaging through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens in sequence.

Preferably, the second lens element, the fourth lens element, the fifth lens element and the sixth lens element are made of plastic material.

Preferably, the second lens and the fifth lens compensate for a focus shift of the fourth lens.

Preferably, the second lens, the fourth lens, the fifth lens and the sixth lens are aspherical mirrors.

Preferably, the third lens has an edge thickness greater than 2 mm.

Preferably, the focal powers of the first lens, the second lens and the fifth lens are negative, and the focal powers of the third lens, the fourth lens and the sixth lens are positive.

Preferably, the intersection point of the curved surface where the light-emitting side of the first lens is located and the optical axis of the wide-angle lens is a point C, and the ratio of the distance between the point C and the plane where the end point of the curved surface is located to the center thickness of the first lens is 1-2.5.

Preferably, the ratio of the focal length of the wide-angle lens to the focal length of the second lens is-0.3 to-0.2; the ratio of the focal length of the wide-angle lens to the focal length of the third lens is 0.4-0.5; the ratio of the focal length of the wide-angle lens to the focal length of the fourth lens is 0.7-0.8; the ratio of the focal length of the wide-angle lens to the focal length of the fifth lens is-0.95 to-0.85; the ratio of the focal length of the wide-angle lens to the focal length of the sixth lens is 0.3-0.4.

Preferably, the total system length of the wide-angle lens is less than 8.5 mm.

According to the technical scheme, the third lens made of glass is arranged between the second lens and the fourth lens, the first lens made of glass is arranged on the light inlet side of the second lens, and the glass lens is slightly influenced by temperature, so that when the temperature changes, other lenses on two sides of the third lens can mutually offset focus offset caused by temperature change according to the optical performance of the other lenses, the integral imaging quality of the lens is guaranteed, the high resolution is achieved at normal temperature, and the environmental adaptability of the wide-angle lens is greatly improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a wide-angle lens according to an embodiment of the present invention;

FIG. 2 is a graph of the modulation transfer function of the wide-angle lens of the present invention;

FIG. 3 is a stippled view of a wide-angle lens of the present invention;

FIG. 4 is a distortion diagram of the wide-angle lens of the present invention;

FIG. 5 is a diagram of the chromatic aberration of magnification of the wide-angle lens of the present invention;

FIG. 6 is an illuminance diagram of a wide-angle lens according to the present invention;

FIG. 7 is a defocus plot of the wide-angle lens of the present invention at normal temperature;

FIG. 8 is a defocus plot at-20 ℃ for the wide-angle lens of the present invention;

fig. 9 is a defocus graph of the wide-angle lens of the present invention at 60 ℃.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	First lens	15	Sixth lens element
11	Second lens	16	Optical filter
				12	Third lens	17	Protective flat plate
13	Fourth lens	18	Image plane
				14	Fifth lens element	19	Diaphragm

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

Referring to fig. 1 to 9, the present invention provides a wide-angle lens, which includes a first lens element 10, a second lens element 11, a third lens element 12, a stop 19, a fourth lens element 13, a fifth lens element 14, and a sixth lens element 15, which are sequentially disposed from an object side to an image side, wherein the first lens element 10 and the third lens element 12 are made of glass; the second lens element 11 and the fifth lens element 14 compensate for a focus offset of the fourth lens element 13, and an object-side light ray passes through the first lens element 10, the second lens element 11, the third lens element 12, the stop 19, the fourth lens element 13, the fifth lens element 14, and the sixth lens element 15 in sequence and is transmitted to an image-side imaging device; the optical centers of the first lens 10, the second lens 11, the third lens 12, the diaphragm 19, the fourth lens 13, the fifth lens 14 and the sixth lens 15 are located on the same optical axis.

In this embodiment, the second lens element 11, the fourth lens element 13, the fifth lens element 14 and the sixth lens element 15 are made of plastic material, and the plastic lens elements are easily affected by temperature changes, so when the temperature is increased or decreased, the second lens element 11, the fifth lens element 14 and the fourth lens element 13 all generate focus shifts, and when light passes through the lens elements with focus shifts, the optical path changes, which results in the decrease of the imaging sharpness of the lens. However, since the focal powers of the second lens 11 and the fifth lens 14 are negative and act on divergence of light, and the focal power of the fourth lens 13 is positive and act on convergence of light, the second lens 11 and the fifth lens 14 just correct the optical path shifted by the fourth lens 13, that is, the second lens 11 and the fifth lens 14 have a function of compensating the focus shift of the fourth lens 13. The first lens 10 and the third lens 12 are made of glass, the focal power of the sixth lens 15 is small, and the change of temperature has little influence on the first lens 10, the third lens 12 and the sixth lens 15, so the change of temperature has little influence on the overall optical performance of the wide-angle lens, can keep the original imaging effect, can clearly image in an environment of-20 ℃ to 60 ℃, and has high resolution at normal temperature.

Because the cost of the plastic lens is lower than that of the glass lens, the wide-angle lens only comprising two glass lenses can have good imaging quality and good environmental adaptability under the condition of low cost. As shown in fig. 7 to 9, it can be seen that the wide-angle lens has slightly reduced imaging resolution at-20 ℃ and 60 ° compared to the normal temperature, but the overall optical performance does not change much.

The wide-angle lens satisfies the following relational expression: tan (HFOV)/TTL >0.91, where HFOV is half of the maximum field of view of the wide-angle lens, and TTL is the distance on the optical axis from the incident surface of the first lens of the wide-angle lens to the image plane 18, i.e., the total length of the wide-angle lens, and in the present embodiment, the total system length of the wide-angle lens is less than 8.5 mm. The relation enables the wide-angle lens to be capable of imaging clearly on the image side, and high resolution of the wide-angle lens is guaranteed.

The field of view of the wide-angle lens is 165 degrees.

The wide-angle lens further includes an optical filter 16 and a protection flat plate 17 which are sequentially arranged from the object side to the image side, and the optical filter 16 and the protection flat plate 17 are both located at the light-emitting side of the sixth lens 15. The optical filter 16 has a filtering function, so that imaging is not distorted, a real object shot by the object side can be highly restored by the wide-angle lens, and imaging quality is guaranteed; the protection plate 17 is a glass plate, a sensor (not shown) and an image plane 18 are arranged on the light emergent side of the protection plate 17, and the protection plate 17 mainly functions to protect the sensor and the image plane 18.

In this embodiment, since the hardness of the glass is high, the first lens 10 can not only deflect the light path entering the first lens, but also protect the light path elements disposed on the light emitting side of the first lens 10 from being damaged by the outside.

Since the diaphragm 19 has direct influence on the field of view of the wide-angle lens and the intensity of light entering the lens, the position of the diaphragm 19 affects the volume and the field of view range of the wide-angle lens; in the preferred embodiment, the stop 19 is located between the third lens 12 and the fourth lens 13, which is beneficial to reduce the length and diameter of the lens.

As shown in fig. 1, as an embodiment, the light incident surface of the first lens 10 is a convex surface, the light emitting surface is a concave surface, the focal power of the first lens 10 is negative, the angle of divergence of the light emitted from the first lens 10 is larger than that of the light entering the first lens 10, an intersection point of a curved surface where the light emitting surface of the first lens 10 is located and the optical axis of the wide-angle lens is set as a point C, and a ratio of a distance between the point C and a plane where an end point of the curved surface is located to a central thickness of the first lens 10 is 1-2.5.

The focal power of the second lens 11 is negative, the angle of divergence of the light emitted from the second lens 11 is larger than that of the light entering the second lens 11, the light entering surface is convex, the light exiting surface is concave, a certain distance exists between any concave part of the light exiting surface and the edge, and the ratio of the focal length of the wide-angle lens to the focal length of the second lens 11 is-0.3 to-0.2.

The focal power of the third lens 12 is positive, and the divergence angle of the light after the light is emitted from the third lens 12 is smaller than that before the light enters the third lens 12; the third lens 12 is a biconvex structure, and the income plain noodles of the third lens 12 begins to go into the light side protrusion from the edge, and it is not protruding to the light-emitting side from the edge to go out the plain noodles, and there is certain interval in any protruding position of its play plain noodles and edge, the focus of wide-angle lens with the ratio of the focus of the third lens 12 is 0.4 ~ 0.5, and edge thickness is greater than 2 mm.

The focal power of the fourth lens 13 is positive, and the divergence angle of the light after the light is emitted from the fourth lens 13 is smaller than that before the light enters the fourth lens 13; the fourth lens 13 has a biconvex structure, a certain distance exists between any protruding part of the light incident surface and the edge, the light emergent surface protrudes from the edge to the light emergent side, and the ratio of the focal length of the wide-angle lens to the focal length of the fourth lens 13 is 0.7-0.8.

The focal power of the fifth lens 14 is negative, the angle of divergence of the light emitted from the fifth lens 14 is larger than that of the light emitted from the fifth lens 14 before entering the fifth lens 14, the fifth lens 14 has a double-concave structure, the light incident surface is not recessed from the edge, a certain distance exists between any recessed part of the light incident surface and the edge, and the light emitting surface is recessed from the edge; the ratio of the focal length of the wide-angle lens to the focal length of the fifth lens is-0.95 to-0.85.

The focal power of the sixth lens 15 is positive, and the divergence angle of the light after the light is emitted from the sixth lens 15 is smaller than that before the light enters the sixth lens 15; the sixth lens 15 has a biconvex structure, and the light-emitting surface of the sixth lens has at least one inflection point, the light-emitting surface protrudes from the inflection point to the light-emitting side, the light-in surface does not protrude from the edge, and any protruding part of the light-in surface has a certain distance from the edge; the ratio of the focal length of the wide-angle lens to the focal length of the sixth lens is 0.3-0.4.

In the preferred embodiment, the second lens element 11, the fourth lens element 13, the fifth lens element 14 and the sixth lens element 15 are all aspheric mirrors, which have higher degree of freedom than spherical mirrors and can better correct aberrations, but the cost difference between the plastic aspheric mirror and the spherical mirror is not large, so that high resolution and clearer imaging can be realized at low cost.

In the present embodiment, the refractive index of the first lens element 10 and the refractive index of the third lens element 12 are 1.7 to 1.85, and the abbe number is 30 to 50; the refractive index of the second lens 11, the fourth lens 13, the fifth lens 14 and the sixth lens 15 made of plastic material is 1.45-1.75, the dispersion coefficient of the second lens 11, the fourth lens 13 and the sixth lens 15 is 50-70, and the dispersion coefficient of the fifth lens 14 is 20-30.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The wide-angle lens is characterized by comprising a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a sixth lens, wherein the first lens, the second lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens are sequentially arranged from an object side to an image side, and the light incident surface, the light incident surface and the light emergent surface are convex surfaces and concave surfaces;

the first lens and the third lens are made of glass materials;

the light rays at the object side are transmitted to the image side for imaging through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens and the sixth lens in sequence;

the ratio of the focal length of the wide-angle lens to the focal length of the second lens is-0.3 to-0.2; the ratio of the focal length of the wide-angle lens to the focal length of the third lens is 0.4-0.5; the ratio of the focal length of the wide-angle lens to the focal length of the fourth lens is 0.7-0.8; the ratio of the focal length of the wide-angle lens to the focal length of the fifth lens is-0.95 to-0.85; the ratio of the focal length of the wide-angle lens to the focal length of the sixth lens is 0.3-0.4.

2. The wide-angle lens of claim 1, wherein the second, fourth, fifth and sixth lenses are made of plastic.

3. The wide-angle lens of claim 2, wherein the second lens and the fifth lens compensate for a focus offset of the fourth lens.

4. The wide-angle lens of claim 2, wherein the second, fourth, fifth, and sixth lenses are aspherical lenses.

5. The wide-angle lens of claim 1, wherein the third lens has an edge thickness greater than 2 mm.

6. The wide-angle lens of claim 1, wherein the optical powers of the first, second, and fifth lenses are negative, and the optical powers of the third, fourth, and sixth lenses are positive.

7. The wide-angle lens of claim 1, wherein an intersection point of a curved surface where the light-emitting side of the first lens is located and an optical axis of the wide-angle lens is a point C, and a ratio of a distance between the point C and a plane where an end point of the curved surface is located to a center thickness of the first lens is 1-2.5.

8. The wide-angle lens of claim 1, wherein the total system length of the wide-angle lens is less than 8.5 mm.