CN112285885A

CN112285885A - Optical imaging system, image capturing module and electronic device

Info

Publication number: CN112285885A
Application number: CN202011193305.0A
Authority: CN
Inventors: 王妮妮; 刘彬彬; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-01-29

Abstract

The invention discloses an optical imaging system, an image capturing module and an electronic device. The optical imaging system comprises the following components in sequence from an object side to an image side: a first lens having a bending force; a second lens having a bending force; a third lens having a bending force; and a fourth lens having a bending force; at least one of the first to fourth lenses has a non-rotationally symmetric aspherical surface; the optical imaging system satisfies the following conditional expression: BL/f is more than or equal to 0 and less than or equal to 2. The optical imaging system realizes the lightness, thinness and short total length of the image capturing module through compact spatial arrangement and reasonable bending force distribution, and has lower optical sensitivity and excellent imaging quality; meanwhile, under the condition of limited lens quantity, the degree of freedom of the meridian plane is increased and the image quality is corrected through the non-rotational symmetric aspheric surface, so that the lens can be produced and processed in batch, and the requirements of the current market are met.

Description

Optical imaging system, image capturing module and electronic device

Technical Field

The invention relates to the technical field of optical imaging, in particular to an optical imaging system, an image capturing module and an electronic device.

Background

With the wide application of electronic products such as mobile phones, tablet computers, unmanned planes, computers, and the like in life, various scientific and technical products are gradually improved and developed, wherein the improvement and innovation of the shooting effect of the electronic products become one of the focuses of people.

In the process of implementing the present application, the inventor finds that at least the following problems exist in the prior art: in order to expand the shooting range, a light and thin optical imaging system is gradually becoming a market trend, but for a wide-angle image capturing module, it is still difficult to improve the light and thin optical imaging system while ensuring high pixels.

Disclosure of Invention

In view of the above, it is desirable to provide an optical imaging system, an image capturing module and an electronic device to solve the above problems.

An embodiment of the present application provides an optical imaging system, sequentially from an object side to an image side, comprising:

a first lens having a bending force;

a second lens having a bending force;

a third lens having a bending force; and

a fourth lens having a bending force;

at least one of the first lens to the fourth lens has a non-rotationally symmetric aspherical surface;

the optical imaging system satisfies the following conditional expression:

0≤BL/f≤2；

and BL is the shortest distance from the image side surface of the fourth lens to the imaging surface of the optical imaging system in a direction parallel to the optical axis, and f is the effective focal length of the optical imaging system.

The optical imaging system realizes the lightness, thinness and short total length of the image capturing module through compact spatial arrangement and reasonable bending force distribution, and has lower optical sensitivity and excellent imaging quality; meanwhile, under the condition of limited lens quantity, the degree of freedom of the meridian plane is increased and the image quality is corrected through the non-rotational symmetric aspheric surface, so that the lens can be produced and processed in batch, and the requirements of the current market are met.

In some embodiments, further comprising:

and the diaphragm is arranged between any two lenses of the first lens and the fourth lens.

In this way, the diaphragm can limit the amount of light passing through the optical imaging system.

In some embodiments, the optical imaging system satisfies the following conditional expression:

0mm≤bh-ah≤2mm；

where bh is the maximum effective radius of the image-side surface of the lens closest to the diaphragm-object side, and ah is the maximum effective radius of the object-side surface of the lens closest to the diaphragm-object side.

Thus, the change of the refraction angle of the incident light is relatively mild, the generation of more aberration due to too strong refraction change can be avoided, and a large field angle can be realized.

0mm/°≤hmax/FOV≤0.5mm/°；

and hmax is the maximum effective radius of each surface of the first lens to the fourth lens, and the FOV is the maximum field angle of the optical imaging system.

Thus, miniaturization and a large angle of view can be realized.

0≤f/f34≤1；

wherein f is an effective focal length of the optical imaging system, and f34 is a combined focal length of the third lens and the fourth lens.

Thus, a large field angle can be realized by the meandering force distribution.

0mm/°≤f/FOV≤0.5mm/°；

wherein f is the effective focal length of the optical imaging system, and the FOV is the maximum field angle of the optical imaging system.

Thus, the large field angle and the effective focal length of the optical imaging system can be balanced.

45≤(V1+V2+V3+V4)/4≤50；

wherein V1 is the abbe number of the first lens, V2 is the abbe number of the second lens, V3 is the abbe number of the third lens, and V4 is the abbe number of the fourth lens.

Thus, chromatic aberration can be corrected.

2≤TTL/IMGH≤4；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical imaging system, and IMGH is half of an image height corresponding to a maximum field angle of the optical imaging system.

Thus, the miniaturization of the image capturing module can be realized.

An embodiment of the present application further provides an image capturing module, including:

the optical imaging system described above; and

a photosensitive element disposed on an image side of the optical imaging system.

The optical imaging system in the image capturing module realizes the lightness, thinness and short total length of the image capturing module through compact spatial arrangement and reasonable bending force distribution, and has lower optical sensitivity and excellent imaging quality; meanwhile, under the condition of limited lens quantity, the degree of freedom of the meridian plane is increased and the image quality is corrected through the non-rotational symmetric aspheric surface, so that the lens can be produced and processed in batch, and the requirements of the current market are met.

An embodiment of the present application further provides an electronic apparatus, including:

a housing; and

the image capturing module is mounted on the shell.

The optical imaging system in the electronic device realizes the lightness, thinness and short total length of the image capturing module through compact spatial arrangement and reasonable tortuosity distribution, and has lower optical sensitivity and excellent imaging quality; meanwhile, under the condition of limited lens quantity, the degree of freedom of the meridian plane is increased and the image quality is corrected through the non-rotational symmetric aspheric surface, so that the lens can be produced and processed in batch, and the requirements of the current market are met.

Drawings

Fig. 1 is a schematic structural view of an optical imaging system according to a first embodiment of the present invention.

FIG. 2 is a diagram of the first embodiment of the present invention with the RMS spot diameter in the first quadrant.

Fig. 3 is a schematic structural view of an optical imaging system according to a second embodiment of the present invention.

FIG. 4 is a diagram of the RMS spot diameter in the first quadrant for an optical imaging system in accordance with a second embodiment of the invention.

Fig. 5 is a schematic structural view of an optical imaging system according to a third embodiment of the present invention.

FIG. 6 is a diagram of the RMS spot diameter in the first quadrant for an optical imaging system in accordance with a third embodiment of the invention.

Fig. 7 is a schematic structural view of an optical imaging system according to a fourth embodiment of the present invention.

FIG. 8 is a diagram of an optical imaging system according to a fourth embodiment of the present invention with the RMS spot diameter in the first quadrant.

Fig. 9 is a schematic structural view of an optical imaging system according to a fifth embodiment of the present invention.

FIG. 10 is a diagram of an optical imaging system according to a fifth embodiment of the present invention with the RMS spot diameter in the first quadrant.

Fig. 11 is a schematic structural view of an optical imaging system according to a sixth embodiment of the present invention.

FIG. 12 is a diagram of an optical imaging system according to a sixth embodiment of the present invention with the RMS spot diameter in the first quadrant.

Fig. 13 is a schematic configuration diagram of an optical imaging system according to a seventh embodiment of the present invention.

FIG. 14 is a diagram of an optical imaging system according to a seventh embodiment of the invention with the RMS spot diameter in the first quadrant.

Fig. 15 is a schematic structural diagram of an electronic device according to an embodiment of the invention.

Description of the main elements

Electronic device 1000

Image capturing module 100

Optical imaging system 10

First lens L1

Second lens L2

Third lens L3

Fourth lens L4

Infrared filter L5

Stop STO

Object sides S1, S4, S6, S8 and S10

Like sides S2, S5, S7, S9, S11

Image forming surface S12

Photosensitive element 20

Housing 200

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

Referring to fig. 1, the embodiment of the invention provides an optical imaging system 10 including, in order from an object side to an image side, a first lens element L1 with refractive power, a second lens element L2 with refractive power, a third lens element L3 with refractive power, and a fourth lens element L4 with refractive power.

The first lens L1 has an object-side surface S1 and an image-side surface S2; the second lens L2 has an object-side surface S4 and an image-side surface S5; the third lens L3 has an object-side surface S6 and an image-side surface S7; the fourth lens L4 has an object-side surface S8 and an image-side surface S9; at least one lens of the first lens L1 to the fourth lens L4 has a non-rotationally symmetric aspherical surface.

The optical imaging system 10 satisfies the following conditional expressions:

0≤BL/f≤2；

where BL is the shortest distance from the image-side surface S9 of the fourth lens L4 to the imaging surface S12 of the optical imaging system 10 in parallel to the optical axis direction, and f is the effective focal length of the optical imaging system 10.

The optical imaging system 10 realizes the lightness and thinness of the image capturing module and has the characteristic of shorter total length through compact spatial arrangement and reasonable bending force distribution, and has lower optical sensitivity and excellent imaging quality; and under the limited lens quantity, through non-rotational symmetry aspheric surface, increase the degree of freedom of meridian plane and corrected the image quality, can carry out batch production processing, satisfy the demand in current market.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: BL/f is more than or equal to 0.539 and less than or equal to 1.218; thus, the back focal length of the optical imaging system 10 can be shortened, the overall volume is prevented from being too large, and the optical imaging system is favorable for being carried on a miniaturized electronic device; meanwhile, the adjusting range of the automatic focusing assembly when the optical imaging system 10 carries the photosensitive chip can be increased. However, when the value of BL/f exceeds the above range, it is disadvantageous to shorten the back focal length of the optical imaging system 10, and the entire volume is too large, which is disadvantageous to mounting in a miniaturized electronic device.

In some embodiments, the optical imaging system 10 further includes a stop STO. The stop STO is provided between any two lenses of the first lens L1 to the fourth lens L4, and thus, the stop STO can limit the amount of light passing through the optical imaging system 10.

In some embodiments, optical imaging system 10 further includes an infrared filter L5, infrared filter L5 having an object side S10 and an image side S11. The infrared filter L5 is disposed at the image side of the fourth lens element L4 to filter out light in other wavelength bands, such as visible light, and only let infrared light pass through, so that the optical imaging system 10 can also image in dim environments and other special application scenarios.

In some embodiments, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all made of plastic, and in this case, the plastic lens can reduce the weight of the optical imaging system 10 and reduce the production cost. In some embodiments, the first lens element L1, the second lens element L2, the third lens element L3 and the fourth lens element L4 are made of glass, so that the optical imaging system 10 can endure higher temperature and has better optical performance. In other embodiments, only the first lens L1 may be made of glass, and the other lenses are made of plastic, in which case, the first lens L1 closest to the object side can better withstand the influence of the ambient temperature on the object side, and the production cost of the optical imaging system 10 is kept low because the other lenses are made of plastic. In other embodiments, the material of the first lens L1 is glass, and the materials of the other lenses can be combined arbitrarily.

In some embodiments, the optical imaging system 10 satisfies the following conditional expressions:

0mm≤bh-ah≤2mm；

where bh is the maximum effective radius of the image-side surface of the lens closest to the object side of the stop STO, and ah is the maximum effective radius of the object-side surface of the lens closest to the object side of the stop STO.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: bh-ah is more than or equal to 0.216 and less than or equal to 1.174; thus, the change of the refraction angle of the incident light is relatively mild, the generation of more aberration due to too strong refraction change can be avoided, and a large field angle can be realized. However, when the value of bh — ah exceeds the above range, the refractive angle change of incident light is too strong and more aberrations are likely to be generated.

0mm/°≤hmax/FOV≤0.5mm/°；

where hmax is the maximum effective radius in each surface of the first lens L1 to the fourth lens L4, and FOV is the maximum angle of view of the optical imaging system 10.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: 0.01mm/° hmax/FOV ≦ 0.013mm/°; thus, miniaturization and a large angle of view can be realized. However, when the value hmax/FOV exceeds the above range, it is not advantageous to achieve miniaturization and a large field angle of the optical imaging system 10.

0≤f/f34≤1；

where f is an effective focal length of the optical imaging system 10, and f34 is a combined focal length of the third lens L3 and the fourth lens L4.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: f/f34 is more than or equal to 0.13 and less than or equal to 0.983; thus, a large field angle can be realized by the meandering force distribution. However, when the value of f/f34 is out of the above range, it is disadvantageous to achieve a large angle of view.

0mm/°≤f/FOV≤0.5mm/°；

where f is the effective focal length of the optical imaging system 10 and the FOV is the maximum field angle of the optical imaging system 10.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: f/FOV is less than or equal to 0.015 mm/degree; in this manner, the large field angle and the effective focal length of the optical imaging system 10 can be balanced. However, when the value of f/FOV is beyond the above range, it is not favorable to balance the large field angle and the effective focal length of the optical imaging system 10.

45≤(V1+V2+V3+V4)/4≤50；

wherein V1 is the abbe number of the first lens L1 under d light, V2 is the abbe number of the second lens L2 under d light, V3 is the abbe number of the third lens L3 under d light, and V4 is the abbe number of the fourth lens L4 under d light.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: 46.755 (V1+ V2+ V3+ V4)/4 is not more than 47.036; thus, chromatic aberration can be corrected. However, when the value of (V1+ V2+ V3+ V4)/4 is out of the above range, correction of the color difference is not facilitated.

2≤TTL/IMGH≤4；

wherein, TTL is a distance on the optical axis from the object-side surface S1 of the first lens element L1 to the imaging surface S12 of the optical imaging system 10, and IMGH is half of the image height corresponding to the maximum field angle of the optical imaging system 10.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: TTL/IMGH is not less than 2.053 and not more than 3.608; thus, the miniaturization of the image capturing module can be realized. However, when the value of TTL/IMGH is beyond the above range, it is not favorable to miniaturize the image capturing module.

-0.5≤L4S1C5*V4≤0.5；

wherein L4S1C5 is the coefficient of the fourth zernike polynomial of the object-side surface S8 of the fourth lens L4, and V4 is the abbe number of the fourth lens L4.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: -0.08 ≤ L4S1C5 × V4 ≤ 0.128; in this way, a non-rotationally symmetric aspheric surface can be fitted using mutually orthogonal polynomials inside the unit circle, and particularly, primary astigmatism in the x direction can be balanced by the L4S1C5, and a material with small chromatic dispersion is used, so that a free-form surface can be realized by a resin molding process, and the image quality of the large-field-angle optical imaging system 10 can be improved.

-10≤L4S1C6*V4≤0；

wherein L4S1C6 is the coefficient of the fifth zernike polynomial of the object-side surface S8 of the fourth lens L4, and V4 is the abbe number of the fourth lens L4.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: -7.041 ≤ L4S1C6 × V4 ≤ 2.351; in this way, the rotationally asymmetric aspheric surface can be fitted using mutually orthogonal polynomials inside the unit circle, and particularly, the primary astigmatism in the y direction is balanced by the L4S1C6, and a material with small chromatic dispersion is used, so that a plurality of base planes can be used for fitting a surface of an arbitrary shape, and the image quality of the large-field-angle optical imaging system 10 can be improved.

-40≤L4S1C2*FOV≤-10；

where L4S1C2 is the coefficient of the first term zernike polynomial of the object-side surface S8 of the fourth lens L4, and the FOV is the maximum field angle of the optical imaging system 10.

Wherein, the optical imaging system 10 further satisfies the following conditional expression: -30.626 ≤ L4S1C2 ≤ FOV-11.752; in this manner, by adding meridional tilt control, the wide angle and distortion of the optical imaging system 10 can be balanced.

First embodiment

Referring to fig. 1, the optical imaging system 10 in the embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative bending force, a second lens L2 with positive bending force, a third lens L3 with positive bending force, a fourth lens L4 with negative bending force, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region, the image-side surface S2 of the first lens element L1 is concave at the paraxial region, the object-side surface S4 of the second lens element L2 is concave at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is concave at the paraxial region.

The object-side surface S1 of the first lens L1 is convex at the near circumference, the image-side surface S2 of the first lens L1 is concave at the near circumference, the object-side surface S4 of the second lens L2 is concave at the near circumference, the image-side surface S5 of the second lens L2 is convex at the near circumference, the object-side surface S6 of the third lens L3 is concave at the near circumference, the image-side surface S7 of the third lens L3 is convex at the near circumference, the object-side surface S8 of the fourth lens L4 is concave at the near circumference, and the image-side surface S9 of the fourth lens L4 is convex at the near circumference.

When the optical imaging system 10 is used for imaging, light emitted or reflected by a subject enters the optical imaging system 10 from the object side direction, and passes through the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the infrared filter L5 in sequence, and finally converges on the imaging surface S12.

Table 1 shows a table of characteristics of the optical imaging system 10 of the present embodiment, the reference wavelength of the focal length, the refractive index, and the abbe number is 587.56nm, and the units of the Y radius, the thickness, and the focal length are all millimeters (mm).

Table 1

Where f is the effective focal length of the optical imaging system 10, FNO is the aperture size of the optical imaging system 10, and FOV is the maximum field angle of the optical imaging system 10.

The rotationally symmetric aspherical surface types in the first lens L1 to the fourth lens L4 are defined by the following formulas:

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is the inverse of the radius of curvature R in table 2); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 2 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the first embodiment.

TABLE 2

The non-rotationally symmetric aspherical surface types in the first lens L1 to the fourth lens L4 are defined by the following formulas:

wherein z is a plane parallel to the z-axis directionRise; c is the vertex curvature of the non-rotationally symmetric aspheric surface; k is a conic coefficient;

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 3 gives the non-rotationally symmetric aspheric coefficients of the lenses that can be used in the first embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

TABLE 3

Fig. 2 shows the size of the RMS spot diameter of the optical imaging system in the first embodiment at different image height positions in the first quadrant, i.e. the relation between the RMS spot diameter and the real ray image height. In FIG. 2, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean RMS spot diameter is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 2, the optical imaging system provided in the first embodiment can achieve good imaging quality.

Second embodiment

Referring to fig. 3, the optical imaging system 10 in the embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative bending force, a second lens L2 with positive bending force, a third lens L3 with negative bending force, a fourth lens L4 with positive bending force, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is concave at the paraxial region, the image-side surface S2 of the first lens element L1 is convex at the paraxial region, the object-side surface S4 of the second lens element L2 is convex at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is concave at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is concave at the paraxial region.

Table 4 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 4

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is the inverse of the radius of curvature R in table 5); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 5 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the second embodiment.

TABLE 5

wherein z is the rise of a plane parallel to the z-axis direction; c is the vertex curvature of the non-rotationally symmetric aspheric surface; k is a conic coefficient;

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 6 gives the non-rotationally symmetric aspheric coefficients of the lenses that can be used in the second embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient which is not given is 0,the following is C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

TABLE 6

Fig. 4 shows the size of the RMS spot diameter of the optical imaging system in the second embodiment at different image height positions in the first quadrant, i.e. the RMS spot diameter versus the real ray image height. In FIG. 4, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean RMS spot diameter is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 4, the optical imaging system provided in the second embodiment can achieve good imaging quality.

Third embodiment

Referring to fig. 5, the optical imaging system 10 in the embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative refractive power, a second lens L2 with positive refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region, the image-side surface S2 of the first lens element L1 is concave at the paraxial region, the object-side surface S4 of the second lens element L2 is convex at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S8 of the fourth lens element L4 is concave at the paraxial region.

Table 7 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 7

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is a curvature half of Table 8The inverse of radius R); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 8 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the third embodiment.

TABLE 8

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 9 gives the non-rotationally symmetric aspheric coefficients of the lens that can be used in the third embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

TABLE 9

Fig. 6 shows the size of the RMS spot diameter of the optical imaging system in the third embodiment at different image height positions in the first quadrant, i.e. the relation of the RMS spot diameter to the real ray image height. In FIG. 6, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean RMS spot diameter is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 6, the optical imaging system according to the third embodiment can achieve good imaging quality.

Fourth embodiment

Referring to fig. 7, the optical imaging system 10 in the embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative bending force, a second lens L2 with positive bending force, a third lens L3 with positive bending force, a fourth lens L4 with negative bending force, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is concave at the paraxial region, the image-side surface S2 of the first lens element L1 is convex at the paraxial region, the object-side surface S4 of the second lens element L2 is convex at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is concave at the paraxial region.

Table 10 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 10

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is the inverse of the radius of curvature R in table 11); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 11 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the fourth embodiment.

TABLE 11

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 12 shows non-rotationally symmetric aspheric coefficients of the lens that can be used in the fourth embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

TABLE 12

Fig. 8 shows the size of the RMS spot diameter of the optical imaging system in the fourth embodiment at different image height positions in the first quadrant, i.e. the relation of the RMS spot diameter to the real ray image height. In fig. 8, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean of the RMS spot diameters is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 8, the optical imaging system according to the fourth embodiment can achieve good imaging quality.

Fifth embodiment

Referring to fig. 9, the optical imaging system 10 of the present embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is concave at the paraxial region, the image-side surface S2 of the first lens element L1 is convex at the paraxial region, the object-side surface S4 of the second lens element L2 is concave at the paraxial region, the image-side surface S5 of the second lens element L2 is concave at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is concave at the paraxial region.

Table 13 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 13

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is the inverse of radius of curvature R in table 14); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 14 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the fifth embodiment.

TABLE 14

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 15 shows non-rotationally symmetric aspheric coefficients of the lens that can be used in the fifth embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

Watch 15

Fig. 10 shows the size of the RMS spot diameter of the optical imaging system in the fifth embodiment at different image height positions in the first quadrant, i.e., the relation between the RMS spot diameter and the real ray image height. In fig. 10, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean of the RMS spot diameters is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 10, the optical imaging system according to the fifth embodiment can achieve good imaging quality.

Sixth embodiment

Referring to fig. 11, the optical imaging system 10 of the present embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative bending force, a second lens L2 with positive bending force, a third lens L3 with positive bending force, a fourth lens L4 with negative bending force, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is concave at the paraxial region, the image-side surface S2 of the first lens element L1 is convex at the paraxial region, the object-side surface S4 of the second lens element L2 is convex at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is concave at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is convex at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is concave at the paraxial region.

Table 16 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 16

wherein χ is a distance from the aspheric surface at a position of height h along the optical axis directionDistance rise of the vertex; c. C₀Paraxial curvature being a rotationally symmetric aspherical surface, c ₀1/R (i.e., paraxial curvature c)₀Is the inverse of radius of curvature R in table 17); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 17 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the sixth embodiment.

TABLE 17

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 18 shows non-rotationally symmetric aspherical coefficients that can be used for the lens in the sixth embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

Watch 18

Fig. 12 shows the size of the RMS spot diameter of the optical imaging system in the sixth embodiment at different image height positions in the first quadrant, i.e., the relation between the RMS spot diameter and the real ray image height. In fig. 12, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean of the RMS spot diameters is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 12, the optical imaging system according to the sixth embodiment can achieve good imaging quality.

Seventh embodiment

Referring to fig. 13, the optical imaging system 10 in the embodiment includes, from the object side to the image side, a stop STO, a first lens L1 with negative bending force, a second lens L2 with positive bending force, a third lens L3 with positive bending force, a fourth lens L4 with negative bending force, and an ir filter L5.

The object-side surface S1 of the first lens element L1 is concave at the paraxial region, the image-side surface S2 of the first lens element L1 is concave at the paraxial region, the object-side surface S4 of the second lens element L2 is concave at the paraxial region, the image-side surface S5 of the second lens element L2 is convex at the paraxial region, the object-side surface S6 of the third lens element L3 is convex at the paraxial region, the image-side surface S7 of the third lens element L3 is convex at the paraxial region, the object-side surface S8 of the fourth lens element L4 is concave at the paraxial region, and the image-side surface S9 of the fourth lens element L4 is convex at the paraxial region.

The object-side surface S1 of the first lens L1 is convex at the near circumference, the image-side surface S2 of the first lens L1 is concave at the near circumference, the object-side surface S4 of the second lens L2 is concave at the near circumference, the image-side surface S5 of the second lens L2 is convex at the near circumference, the object-side surface S6 of the third lens L3 is convex at the near circumference, the image-side surface S7 of the third lens L3 is convex at the near circumference, the object-side surface S8 of the fourth lens L4 is concave at the near circumference, and the image-side surface S9 of the fourth lens L4 is convex at the near circumference.

Table 19 shows a table of characteristics of the optical imaging system of the present embodiment, the reference wavelength of the focal length, refractive index, and abbe number is 587.56nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

Table 19

wherein chi is the rise of the distance from the vertex of the aspheric surface when the aspheric surface is at the position with the height of h along the optical axis direction; c0 is the paraxial curvature of the rotationally symmetric aspheric surface, c0 ═ 1/R (i.e., paraxial curvature c0 is the reciprocal of radius of curvature R in table 20); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 20 shows the high-order coefficient coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 of the rotationally symmetric aspheric surfaces that can be used in the seventh embodiment.

Watch 20

r is the radius value; ZP_jIs the jth Zernike polynomial; c_(j+1)Is ZP_jThe coefficient of (a). Table 21 shows non-rotationally symmetric aspherical coefficients that can be used for the lens in the seventh embodiment. Zernike terms from ZP₁To ZP₆₆Having a corresponding coefficient C₂To C₆₇The coefficient not given is 0, hereinafter C₂、C₅、C₆、C₁₂、C₁₃、C₁₄、C₂₃、C₂₄、C₂₅、C₂₆、C₃₈、C₃₉、C₄₀、C₄₁、C₄₂、C₅₇、C₅₈、C₅₉、C₆₀、C₆₁、C₆₂And (4) the coefficient.

TABLE 21

Fig. 14 shows the size of the RMS spot diameter of the optical imaging system in the seventh embodiment at different image height positions in the first quadrant, i.e., the relation between the RMS spot diameter and the real ray image height. In fig. 14, the minimum RMS spot diameter is in mm, the maximum RMS spot diameter is in mm, the mean of the RMS spot diameters is in mm, and the standard deviation of the RMS spot diameters is in mm. As can be seen from fig. 14, the optical imaging system according to the seventh embodiment can achieve good imaging quality.

Table 22 shows values of BL/f, bh-ah, hmax/FOV, f/f34, f/FOV, (V1+ V2+ V3+ V4)/4, TTL/IMGH, L4S1C 5V 4, L4S1C 6V 4, and L4S1C2 FOV in the optical imaging systems of the first to seventh embodiments.

Table 22

Referring to fig. 15, the optical imaging system 10 according to the embodiment of the invention can be applied to the image capturing module 100 according to the embodiment of the invention. The image capturing module 100 includes a photosensitive element 20 and the optical imaging system 10 of any of the above embodiments. The photosensitive element 20 is disposed on the image side of the optical imaging system 10.

The photosensitive element 20 may be a Complementary Metal Oxide Semiconductor (CMOS) image sensor or a Charge-coupled Device (CCD).

The optical imaging system 10 in the image capturing module 100 realizes the lightness and thinness of the image capturing module and has the characteristic of short total length through compact spatial arrangement and reasonable bending force distribution, and has low optical sensitivity and excellent imaging quality; and under the limited lens quantity, through non-rotational symmetry aspheric surface, increase the degree of freedom of meridian plane and corrected the image quality, can carry out batch production processing, satisfy the demand in current market.

Referring to fig. 15, the image capturing module 100 according to the embodiment of the invention can be applied to the electronic device 1000 according to the embodiment of the invention. The electronic device 1000 includes a housing 200 and an image capturing module 100, wherein the image capturing module 100 is mounted on the housing 200.

The electronic device 1000 according to the embodiment of the present invention includes, but is not limited to, an imaging-enabled electronic device such as a car recorder, a smart phone, a tablet computer, a notebook computer, an electronic book reader, a Portable Multimedia Player (PMP), a portable phone, a video phone, a digital still camera, a mobile medical device, and a wearable device.

The optical imaging system 10 in the electronic device 1000 realizes the lightness and thinness of the image capturing module and has the characteristic of short total length through compact spatial arrangement and reasonable bending force distribution, and has low optical sensitivity and excellent imaging quality; and under the limited lens quantity, through non-rotational symmetry aspheric surface, increase the degree of freedom of meridian plane and corrected the image quality, can carry out batch production processing, satisfy the demand in current market.

Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An optical imaging system, comprising, in order from an object side to an image side:

a first lens having a bending force;

a second lens having a bending force;

a third lens having a bending force; and

a fourth lens having a bending force;

the optical imaging system satisfies the following conditional expression:

0≤BL/f≤2；

2. The optical imaging system of claim 1, further comprising:

3. The optical imaging system of claim 2, wherein the optical imaging system satisfies the following conditional expression:

0mm≤bh-ah≤2mm；

4. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

0mm/°≤hmax/FOV≤0.5mm/°；

5. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

0≤f/f34≤1；

6. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

0mm/°≤f/FOV≤0.5mm/°；

7. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

45≤(V1+V2+V3+V4)/4≤50；

8. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

2≤TTL/IMGH≤4；

9. An image capturing module, comprising:

the optical imaging system of any one of claims 1 to 8; and

10. An electronic device, comprising:

a housing; and

the image capturing module of claim 9, wherein the image capturing module is mounted on the housing.