WO2024020893A1

WO2024020893A1 - Imaging lens assembly, camera module, and imaging device

Info

Publication number: WO2024020893A1
Application number: PCT/CN2022/108382
Authority: WO
Inventors: Kenshi Nabeta
Original assignee: Guangdong Oppo Mobile Telecommunications Corp., Ltd.
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2024-02-01

Abstract

An imaging lens assembly (2), a camera module (11), and an imaging device (1) are provided. The imaging lens assembly (2) includes an optical system including: in order from an object side to an image side, two aperture diaphragms of an adjustable diaphragm (1a) and an aperture diaphragm (1b), a diameter of the adjustable diaphragm (1a) not regulating a maximum diameter and a diameter of the aperture diaphragm (1b) regulating the maximum diameter, and eight lenses. The eight lenses of the optical system include in order from the object side, a first lens (L1) that has positive refractive power and whose object-side surface has a convex shape and image-side surface has a concave shape near a paraxial area; a second lens (L2) that has negative refractive power; a third lens (L3) that has positive refractive power; a fourth lens (L4); a fifth lens (L5); a sixth lens (L6); a seventh lens (L7); and an eighth lens (L8) that has negative refractive power and whose image-side surface has a concave shape. The imaging lens assembly (2) satisfies the following conditional expressions: Fno_min<2.4; HFOV>30, FL/Fno_min/((18*FL/ImgH*21.63)/FL-1)>0.085; and FL/Fno_max/((18*FL/ImgH*21.63)/FL-1)<0.080. The imaging lens assembly (2), the camera module (11), and the imaging device (1) can obtain a sufficient backgroud blur effect while maintaining an image quality and a resolution.

Description

IMAGING LENS ASSEMBLY, CAMERA MODULE, AND IMAGING DEVICE

TECHNICAL FIELD

The present disclosure relates to an imaging lens assembly having a plurality of lenses, an aperture diaphragm, and an adjustable diaphragm, a camera module, and an imaging device.

BACKGROUND

A main camera having a plurality of lenses, an aperture diaphragm, an adjustable diaphragm, and a sensor has been developed. The main camera can adjust an amount of light entering the sensor by using the adjustable diaphragm. For example, at the time of a digital zoom, a technology of squeezing the adjustable diaphragm to raise resolution has been developed.

[Prior Art document (s) ]

[Patent literature 1]

U.S. Patent Application Publication No. 2020/0257087

[Patent literature 2]

Chinese Patent No. 101918874

SUMMARY

[Problem to be Solved by the Invention]

However, in the case of the main camera whose F-number (Fno) is about 1.8, it is difficult to shoot a sufficiently blurred background image during portrait shooting or macro shooting. Moreover, a camera whose Fno is 1.4 is developed, but it is difficult to obtain a sufficient background blur effect due to a small sensor size. Moreover, even if Fno is sufficiently small and a sensor size is sufficiently large, it may be determined that an image quality of a captured image is bad if a background is excessively blurred.

The present disclosure has been made in view of the above problem, and an object of the present disclosure is to provide an imaging lens assembly, a camera module, and an imaging device, which can obtain a sufficient background blur effect while maintaining an image quality and a resolution.

[Means for Solving Problem]

To solve the problem described above and achieve the object, a lens system includes an optical system including: in order from an object side to an image side, two aperture diaphragms of an adjustable diaphragm whose diameter is not regulated at a maximum diameter and an aperture diaphragm whose diameter is regulated at a maximum diameter; and eight lenses. The eight lenses of the optical system include: in order from the object side, a first lens that has positive refractive power and whose object-side surface has a convex shape and image-side surface has a concave shape near a paraxial area; a second lens that has negative refractive power; a third lens that has positive refractive power; a fourth lens; a fifth lens; a sixth lens; a seventh lens; and an eighth lens that has negative refractive power and whose image-side surface has a concave shape. The lens system satisfies the following conditional expressions:

Fno_min < 2.4, wherein Fno_min: Fno at a maximum diameter;

HFOV > 30, wherein HFOV: a half angle of view corresponding to an effective pixel area of an imaging surface of the optical system;

FL/Fno_min/ ( (18*FL/ImgH*21.63) /FL-1) > 0.085; and

FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) < 0.080, wherein FL: a focal length of the optical system, Fno_max: Fno at a minimum diameter, and ImgH: a half-diagonal length of the effective pixel area of the imaging surface of the optical system.

[Effect of the Invention]

The imaging lens assembly, the camera module, and the imaging device according to the present disclosure have an effect that can obtain a sufficient background blur effect while maintaining an image quality and a resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram illustrating an imaging device according to an embodiment;

FIG. 1B is a diagram illustrating an example of a configuration of a camera module according to the present embodiment;

FIG. 1C is a diagram explaining a mechanism of a background blur during portrait shooting;

FIG. 1D is a diagram explaining an example of a background blur obtained by the imaging device according to the present embodiment;

FIG. 2 is a diagram illustrating a curvature radius Ri, a distance D, a refractive index Nd, and an Abbe number νd of lenses included in an imaging lens assembly according to Example 1;

FIG. 3 is a diagram illustrating a focal length, Fno, an angle of view, an INF total track length, a sensor size, and a flange focal length of the imaging lens assembly according to Example 1;

FIG. 4 is a diagram illustrating a focal length of each lens included in the imaging lens assembly according to Example 1;

FIG. 5 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 1;

FIG. 6 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 1;

FIG. 7 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 1;

FIG. 8 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 2;

FIG. 9 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 2;

FIG. 10 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 2;

FIG. 11 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 2;

FIG. 12 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 2;

FIG. 13 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 2;

FIG. 14 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 3;

FIG. 15 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 3;

FIG. 16 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 3;

FIG. 17 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 3;

FIG. 18 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 3;

FIG. 19 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 3;

FIG. 20 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 4;

FIG. 21 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 4;

FIG. 22 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 4;

FIG. 23 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 4;

FIG. 24 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 4;

FIG. 25 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 4;

FIG. 26 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 5;

FIG. 27 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 5;

FIG. 28 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 5;

FIG. 29 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 5;

FIG. 30 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 5;

FIG. 31 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 5;

FIG. 32 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 6;

FIG. 33 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 6;

FIG. 34 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 6;

FIG. 35 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 6;

FIG. 36 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 6;

FIG. 37 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 6;

FIG. 38 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 7;

FIG. 39 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 7;

FIG. 40 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 7;

FIG. 41 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 7;

FIG. 42 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 7;

FIG. 43 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 7;

FIG. 44 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 8;

FIG. 45 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 8;

FIG. 46 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 8;

FIG. 47 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 8;

FIG. 48 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 8;

FIG. 49 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 8;

FIG. 50 is a diagram explaining an example of a switching process of a background blur amount in the imaging device according to the present embodiment; and

FIG. 51 is a diagram explaining another example of a switching process of a background blur amount in the imaging device according to the present embodiment.

DETAILED DESCRIPTION

Hereinafter, an embodiment of an imaging lens assembly, a camera module, and an imaging device according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to the present embodiment.

FIG. 1A is a schematic diagram illustrating an imaging device 1 according to the present embodiment. As illustrated in FIG. 1A, the imaging device 1 according to the present embodiment includes a camera module 11 and an image processing unit 13. The camera module 11 includes an imaging lens assembly 2, an optical filter 3, an image sensor 4, a board 24, and the like. The imaging lens assembly 2 includes an adjustable diaphragm 1a, an aperture diaphragm 1b, and an optical lens 12.

The image sensor 4 is mounted on the board 24. The image processing unit 13 performs image processing on imaging signals (image data) output from the image sensor 4. Note that the adjustable diaphragm 1a, the aperture diaphragm 1b, the imaging lens assembly 2, the optical filter 3, and the image sensor 4 will be described below.

FIG. 1B is a diagram illustrating an example of a configuration of the camera module according to the present embodiment. FIG. 1C is a diagram explaining a mechanism of a background blur during portrait shooting. FIG. 1D is a diagram explaining an example of a background blur obtained by the imaging device according to the present embodiment. As illustrated in FIG. 1B, the camera module 11 according to the present embodiment includes, in order from the object side to the image side, the adjustable diaphragm 1a, the aperture diaphragm 1b, the imaging lens assembly 2 (example of optical system) , the optical filter 3, and the image sensor 4.

The adjustable diaphragm 1a is an example of an adjustable diaphragm whose aperture is variable and whose diameter of the aperture does not regulate the maximum diameter. The aperture diaphragm 1b is an example of an aperture diaphragm whose diameter of the aperture regulates the maximum diameter. The optical filter 3 is provided between the imaging lens assembly 2 and the image sensor 4 in a direction from the object side to the image side.

The image sensor 4 has a light receiving surface on which light generated from an object is formed as an image through an optical system such as the imaging lens assembly 2 and the optical filter 3. The optical filter 3 may be an IR cut filter, an IR absorption filter, or the like. The image sensor 4 outputs an electrical signal obtained by photo-electrically converting light and darkness by the light of the image formed on the light receiving surface. In other words, the image sensor 4 constitutes an example of an image sensor configured to output an imaging signal according to an optical image formed by the imaging lens assembly 2.

The imaging lens assembly 2 is an example of an optical system that has eight lenses. Optionally, the imaging lens assembly 2 includes, in order from the object side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.

The first lens L1 is a lens that has positive refractive power and whose object-side surface has a convex shape and image-side surface has a concave shape near a paraxial area. The second lens L2 is a lens that has negative refractive power. The third lens L3 is a lens that has positive refractive power. The eighth lens L8 is a lens that has negative refractive power and whose image-side surface has a concave shape.

The imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (1) to (4) . As a result, it is possible to suppress a background blur to raise resolution when a blurred background is not desired. Moreover, it is possible to provide an optimum background blur when performing portrait shooting or macro shooting.

Fno_min < 2.4 (1)

Fno_min: Fno at maximum diameter.

HFOV > 30 (2)

HFOV: Half angle of view corresponding to effective pixel area of imaging surface of whole lens system (the imaging lens assembly 2) .

FL/Fno_min/ ( (18*FL/ImgH*21.63) /FL-1) > 0.085 (3)

FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) < 0.080 (4)

FL: Focal length of whole lens system;

Fno_max: Fno at minimum diameter;

ImgH: Half-diagonal length of effective pixel area of imaging surface of whole lens system.

Herein, a mechanism of a background blur during portrait shooting will be described by using FIG. 1C. The background blur of the imaging device 1 during portrait shooting has the characteristics of the following (1) to (3) :

(1) a background is easier to blur as a focal length is longer;

(2) a background is easy to blur if a sensor size is large;

(3) a background is easier to blur as a diaphragm diameter is larger;

(4) a background is easier to blur as a subject is closer; and

(5) a background is easier to blur as a background is farther.

The conventional optical lens system has Fno of about 1.8, and thus it is difficult to shoot a sufficiently blurred background image when performing portrait shooting or macro shooting as illustrated in FIG. 1D. A camera having Fno of 1.4 has been developed, but it is difficult to obtain a sufficient background blur effect due to a small sensor size. Moreover, even if Fno is sufficiently small and a sensor size is sufficiently large, it may be determined that an image quality of a captured image is bad if a background is excessively blurred. On the contrary, the imaging lens assembly (optical lens system) 2 according to the present embodiment can obtain an optimum background blur effect when performing portrait shooting or macro shooting, and also can select a background blur effect according to a demand of a user by squeezing the aperture of the adjustable diaphragm 1a so as to satisfy the above expressions to obtain an optimum background blur effect, as illustrated in FIG. 1D, and can improve resolution of a background image when a blurred background is not desired.

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (5) to (9) .

F1/FL > 0 (5)

F2/FL < 0 (6)

F3/FL > 0 (7)

F1/F8 < 0 (8)

0.5< (F _L1-L5) /FL < 2.0 (9)

Herein, FL is a focal length of the whole lens system (the imaging lens assembly 2) . Moreover, F1 is a focal length of the first lens L1. Moreover, F2 is a focal length of the second lens L2. Moreover, F3 is a focal length of the third lens L3. F8 is a focal length of the eighth lens L8. (F _L1-L5) is a composite focal length from the first lens L1 to the fifth lens L5.

Moreover, it is desirable that the imaging lens assembly 2 satisfies a conditional expression indicated by the following Expression (10) .

15 < Σ|F (i) /FL| < 500 (10)

Herein, F (i) is a focal length of the i-th lens among the first to eighth lenses L1 to L8.

Moreover, it is desirable that the imaging lens assembly 2 satisfies a conditional expression indicated by the following Expression (11) .

Σ|Ri/FL| > 10 (11)

Herein, Ri is a curvature radius of a lens surface of the i-th lens from the object side of the whole lens system (the imaging lens assembly 2) .

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (12) and (13) .

1.0 < TTL/ (D _L1-L5) < 3.0 (12)

TTL/ (D8) > 30 (13)

Herein, TTL is a distance from an object-side surface on the optical axis of the first lens L1 to a focus position of the whole lens system (the imaging lens assembly 2) . Moreover, (D _L1-L5) is a distance from the object-side surface on the optical axis of the first lens L1 to an image-side surface on the optical axis of the fifth lens L5. (D8) is a distance from an image-side surface on the optical axis of the fourth lens L4 to an object-side surface on the optical axis of the fifth lens L5.

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (14) to (16) .

R2/R1 > 0 (14)

R3/R4 > 0 (15)

R6/R5 > 0 (16)

Herein, R1 is a curvature radius of the object-side surface of the first lens L1. Moreover,

R2 is a curvature radius of the image-side surface of the first lens L1. Moreover, R3 is a curvature radius of the object-side surface of the second lens L2. Moreover, R4 is a curvature radius of the image-side surface of the second lens L2. R5 is a curvature radius of the object-side surface of the third lens L3. R6 is a curvature radius of the image-side surface of the third lens L3.

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (17) and (18) .

R7/R11 > 0 (17)

R14/R13 > 0 (18)

Herein, R7 is a curvature radius of the object-side surface of the fourth lens L4. R11 is a curvature radius of the object-side surface of the sixth lens L6. R13 is a curvature radius of the object-side surface of the seventh lens L7. Moreover, R14 is a curvature radius of the image-side surface of the seventh lens L7.

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (19) to (27) .

(Nd2) < 1.75 (19)

(Nd4) < 1.75 (20)

(Nd5) < 1.75 (21)

(Nd8) < 1.75 (22)

(νd1) > 45 (23)

(νd2) < 35 (24)

(νd6) < 65 (25)

(νd7) < 60 (26)

(νd8) < 60 (27)

Herein, (Nd2) is a refractive index of d-line of the second lens L2. Moreover, (Nd4) is a refractive index of d-line of the fourth lens L4. (Nd5) is a refractive index of d-line of the fifth lens L5. (Nd8) is a refractive index of d-line of the eighth lens L8.

(νd1) : Abbe number of the first lens,

(νd2) : Abbe number of the second lens,

(νd6) : Abbe number of the sixth lens,

(νd7) : Abbe number of the seventh lens, and

(νd8) : Abbe number of the eighth lens.

Moreover, it is desirable that the imaging lens assembly 2 satisfies conditional expressions indicated by the following Expressions (28) to (30) .

TTL/ImgH < 2.5 (28)

TTL/FL > 0.5 (29)

TTL/BFL > 5 (30)

Herein, TTL is a distance from the object-side surface vertex on the optical axis of the first lens L1 to the focus position of the whole lens system (the imaging lens assembly 2) . Moreover, ImgH is a half-diagonal length of the effective pixel area of the imaging surface of the whole lens system (the imaging lens assembly 2) . Moreover, BFL is a distance from a front surface to an image surface of the optical filter 3 such as the IRCF (IR cut filter) .

Moreover, it is desirable that a lens on the most image side among the first to eighth lenses L1 to L8 is formed of aspherical plastic having an inflection point.

Next, examples of a configuration of the imaging lens assembly 2 according to Examples 1 to 8 will be described with reference to FIGS. 2 to 49. Examples 1 to 8 are examples that have different combinations of the curvature radius Ri, the distance D, the refractive index Nd, the Abbe number νd (νd1 to νd8) , the focal length, Fno, the angle of view, the INF total track length, the sensor size, the flange focal length, and the refractive power Li of the first to eighth lenses included in the imaging lens assembly 2. In FIGS. 2, 8, 14, 20, 26, 32, 38, and 44, "LiR1" indicates an object-side surface of the i-th lens, and "LiR2" indicates an image-side surface of the i-th lens. Ri indicates a curvature radius of the i-th lens surface from the object side of the whole lens system (the imaging lens assembly 2) , R15 is a curvature radius of the object-side surface of the eighth lens L8, and R16 is a curvature radius of the image-side surface of the eighth lens L8.

(Example 1)

FIG. 2 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 1. FIG. 3 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 1. FIG. 4 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 1. FIG. 5 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 1. FIG. 6 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 1. FIG. 7 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 1. In (a) of FIG. 7, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 7, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 7, the vertical axis is an image height, and the horizontal axis is a distortion. Note that aspherical coefficients of the imaging lens assembly 2 according to Examples 1 to 8 may be calculated by using the following Expression (31) .

Z=C*h^2/ {1+ [1- (1+K) *C^2*h^2] ^1/2} +ΣAn*h^n (31)

Herein, "n" is an integer number greater than or equal to 3. Moreover, "Z" is a depth of a aspheric surface. Moreover, "C" is a paraxial curvature (=1/R) . "H" is a distance from the optical axis to the lens surface. "K" is an eccentricity (second aspherical coefficient) . "An" is the nth aspherical coefficient.

[Table 1]

Table 1 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 1. As indicated in Table 1, the imaging lens assembly according to Example 1 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 1, the camera module using the imaging lens assembly according to Example 1, and the imaging device using the imaging lens assembly according to Example 1 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 2)

Unlike Example 1, Example 2 assumes that the focal length of the fourth lens L4 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 8 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 2. FIG. 9 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 2. FIG. 10 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 2. FIG. 11 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 2. FIG. 12 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 2. FIG. 13 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 2. In (a) of FIG. 13, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 13, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 13, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 2]

Table 2 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 2. As indicated in Table 2, the imaging lens assembly according to Example 2 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 2, the camera module using the imaging lens assembly according to Example 2, and the imaging device using the imaging lens assembly according to Example 2 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 3)

Unlike Example 1, Example 3 assumes that the focal length of the fifth lens L5 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 14 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 3. FIG. 15 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 3. FIG. 16 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 3. FIG. 17 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 3. FIG. 18 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 3. FIG. 19 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 3. In (a) of FIG. 19, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 19, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 19, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 3]

Table 3 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 3. As indicated in Table 3, the imaging lens assembly according to Example 3 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 3, the camera module using the imaging lens assembly according to Example 3, and the imaging device using the imaging lens assembly according to Example 3 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 4)

Unlike Example 1, Example 4 assumes that the focal length of the fourth lens L4 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 20 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 4. FIG. 21 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 4. FIG. 22 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 4. FIG. 23 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 4. FIG. 24 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 4. FIG. 25 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 4. In (a) of FIG. 25, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 25, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 25, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 4]

Table 4 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 4. As indicated in Table 4, the imaging lens assembly according to Example 4 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 4, the camera module using the imaging lens assembly according to Example 4, and the imaging device using the imaging lens assembly according to Example 4 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 5)

Unlike Example 1, Example 5 assumes that the focal length of the fourth lens L4 is negative, the focal length of the fifth lens L5 is negative, and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 26 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 5. FIG. 27 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 5. FIG. 28 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 5. FIG. 29 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 5. FIG. 30 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 5. FIG. 31 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 5. In (a) of FIG. 31, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 31, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 31, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 5]

Table 5 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 5. As indicated in Table 5, the imaging lens assembly according to Example 5 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 5, the camera module using the imaging lens assembly according to Example 5, and the imaging device using the imaging lens assembly according to Example 5 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 6)

Unlike Example 1, Example 6 assumes that the focal length of the fourth lens L4 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 32 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 6. FIG. 33 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 6. FIG. 34 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 6. FIG. 35 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 6. FIG. 36 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 6. FIG. 37 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 6. In (a) of FIG. 37, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 37, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 37, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 6]

Table 6 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 6. As indicated in Table 6, the imaging lens assembly according to Example 6 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 6, the camera module using the imaging lens assembly according to Example 6, and the imaging device using the imaging lens assembly according to Example 6 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 7)

Unlike Example 1, Example 7 assumes that the focal length of the fourth lens L4 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 38 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 7. FIG. 39 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 7. FIG. 40 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 7. FIG. 41 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 7. FIG. 42 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 7. FIG. 43 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 7. In (a) of FIG. 43, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 43, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 43, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 7]

Table 7 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 7. As indicated in Table 7, the imaging lens assembly according to Example 7 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 7, the camera module using the imaging lens assembly according to Example 7, and the imaging device using the imaging lens assembly according to Example 7 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

(Example 8)

Unlike Example 1, Example 8 assumes that the focal length of the fourth lens L4 is negative and the focal length of the sixth lens L6 is positive, and have different lens parameters (focal length, Fno, angle of view, INF total track length, sensor size, flange focal length, and the like of the imaging lens assembly) from those of Example 1, to be able to further improve design freedom of the camera module 11 while obtaining the same effects as those of Example 1.

FIG. 44 is a diagram illustrating the curvature radius Ri, the distance D, the refractive index Nd, and the Abbe number νd of lenses included in the imaging lens assembly according to Example 8. FIG. 45 is a diagram illustrating the focal length, Fno, the angle of view, the INF total track length, the sensor size, and the flange focal length of the imaging lens assembly according to Example 8. FIG. 46 is a diagram illustrating the focal length of each lens included in the imaging lens assembly according to Example 8. FIG. 47 is a diagram illustrating an example of a configuration of the imaging lens assembly according to Example 8. FIG. 48 is a diagram illustrating aspherical coefficients of the imaging lens assembly according to Example 8. FIG. 49 is a graph illustrating longitudinal aberration of the imaging lens assembly according to Example 8. In (a) of FIG. 49, the vertical axis is a spherical aberration, and the horizontal axis is a focus. In (b) of FIG. 49, the vertical axis is an astigmatism and a field curvature, and the horizontal axis is a focus. In (c) of FIG. 49, the vertical axis is an image height, and the horizontal axis is a distortion.

[Table 8]

Table 8 indicates numerical values of Conditional Expressions (1) to (30) in the imaging lens assembly according to Example 8. As indicated in Table 8, the imaging lens assembly according to Example 8 satisfies Conditional Expressions (1) to (30) . Therefore, the imaging lens assembly according to Example 8, the camera module using the imaging lens assembly according to Example 8, and the imaging device using the imaging lens assembly according to Example 8 have an effect that a sufficient background blur effect can be obtained while maintaining an image quality and a resolution.

Because an amount of light irradiated on an image surface becomes small when Fno_min is 2.4 or more, a captured image darkens and an image quality in a dark place etc. gets worse. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (1) . Note that it is desirable that Fno_min is 2.1 or less.

Moreover, because a focal length becomes long and the total track length of the lens becomes too large when HFOV is 38.5° or less, the product size becomes large and a merit becomes small. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (2) .

Moreover, when FL/Fno_min/ ( (18*FL/ImgH*21.63) /FL-1) is 0.085 or less, a blurred amount of a screen background at portrait shooting or macro shooting in the open diaphragm (the adjustable diaphragm 1a) becomes small, a coordination effect of a main subject becomes thin, and a stage effect is not obtained. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (3) .

Moreover, when FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) is 0.080 or more, because a blurred amount of a screen background at stop-down shooting does not become small and thus a sharp shot of the entire screen cannot be taken, an image having a high resolution cannot be taken. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (4) . To acquire a sharper image, it is desirable that FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) is 0.060 or less.

Moreover, when F1/FL is 0 or less, because power of the first lens L1 becomes negative and a convergent effect of light rays of the entire optical system (the imaging lens assembly 2) becomes small, it is not possible to brighten the lens system. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (5) . To keep the balance between the lens diameter and the optical performance, it is further desirable that F1/FL is 0.5 or more.

Moreover, when F2/FL is 0 or more, negative optical power inside the front lens group becomes small, and a spherical aberration and a chromatic aberration on the axis cannot be corrected. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (6) . To balance with the performance, it is further desirable that F2/FL is -1.0 or less.

Moreover, when F3/FL is 0 or less, because power of the third lens L3 becomes negative and thus a convergent effect of light rays of the entire optical system becomes small, it is not possible to shorten the lens system. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (7) . Moreover, in order to keep the balance between the total track length of the lens and the optical performance, it is further desirable that F3/FL is 2.0 or more.

Moreover, when F1/F8 is 0 or more, power of the eighth lens L8 becomes positive and thus the focal length and the shortening of the flange focal length cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (8) . Moreover, in order to obtain a shortening effect of the effective flange focal length, it is further desirable that F1/F8 is -0.5 or less.

Moreover, when (F _L1-L5) is 2.0 or more, positive optical power of the front lens group becomes weak and thus a spherical aberration and a chromatic aberration on the axis cannot be corrected. Moreover, when (F _L1-L5) is 0.5 or less, positive optical power of the front lens group becomes strong and a sensitivity at manufacturing becomes high to cause the decrease in a yield ratio. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (9) . In order to keep the balance with the performance, it is further desirable that (F _L1-L5) is 0.8 or more and 1.8 or less.

Moreover, when Σ|F (i) /FL| is 15 or less, because power of each lens becomes too strong, a sensitivity when manufacturing lenses rises to affect a yield ratio. Moreover, when Σ|F (i) /FL| is 500 or more, because power of each lens becomes weak and sufficient aberration correction cannot be made, the total track length of the lens becomes large. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly according to the present embodiment satisfies the conditional expression indicated by the above Expression (10) . Moreover, it is further desirable that Σ|F (i) /FL| is about 20 or more and 350 or less.

Moreover, when Σ|Ri/FL| is 10 or less, because power of each lens surface becomes too strong, a high-order aberration occurs and a sensitivity when manufacturing lenses rises to affect a yield ratio. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (11) . Moreover, it is further desirable that Σ|Ri/FL| is 15 or more.

Moreover, when TTL/ (D _L1-L5) is 1.0 or less, because the total track length of the front positive lens group becomes large, aberration correction around the screen in the rear lens cannot be made sufficiently, and the performance cannot be balanced. Moreover, when TTL/ (D _L1-L5) is 3.0 or more, because power of the front positive lens group becomes too strong, an aberration on the axis occurs and a sensitivity when manufacturing lenses rises to affect a yield ratio. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (12) . Moreover, it is further desirable that TTL/ (D _L1-L5) is 1.5 or more and 2.5 or less.

Moreover, when TTL/ (D8) is 30 or less, a distance between the fourth lens L4 and the fifth lens L5 becomes wide, and thus an aberration improvement effect using the refractive index difference and Abbe number difference of the front and rear lenses is not obtained. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (13) . Moreover, it is more desirable that TTL/ (D8) is 40 or more.

Moreover, when R2/R1 is 0 or less, because the first lens L1 has a biconvex shape, the angle of light ray incident on the rear surface of the first lens L1 becomes tight to cause a high-order aberration. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (14) . Moreover, it is further desirable that R2/R1 is 2.0 or more.

Moreover, when R3/R4 is 0 or less, because the second lens L2 has a biconcave shape, the angle of light ray incident on the front surface of the second lens L2 becomes tight to cause a high-order aberration. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (15) . It is further desirable that R3/R4 is 1.0 or more.

Moreover, when R6/R5 is 0 or less, because the third lens L3 has a biconvex shape, the angle of light ray incident on the rear surface of the third lens L3 becomes tight to cause a high- order aberration. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (16) . It is further desirable that R6/R5 is 1.0 or more.

Moreover, when R7/R11 is 0 or less, because the front surface of the fourth lens L4 and the front surface of the sixth lens L6 have different shapes, bending of the light ray is not smooth. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (17) . It is further desirable that R7/R11 is 1.0 or more.

Moreover, when R14/R13 is 0 or less, because the seventh lens L7 has a biconvex shape, positive optical power of the seventh lens L7 becomes too strong and aberration correction is out of balance. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (18) . It is further desirable that R14/R13 is 1.0 or more.

Moreover, when (Nd2) is 1.75 or more, because negative refractive power becomes excessive, it is difficult to manufacture the lens system even if the second lens L2 becomes too thin. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (19) . It is further desirable that (Nd2) is 1.73 or less.

Moreover, when (Nd4) is 1.75 or more, an astigmatism and a field curvature cannot be unbalanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (20) . It is further desirable that (Nd4) is 1.73 or less.

Moreover, when (Nd5) is 1.75 or more, an astigmatism and a field curvature cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (21) . It is further desirable that (Nd5) is 1.73 or less.

Moreover, when (Nd8) is 1.75 or more, because negative refractive power becomes excessive, it is difficult to manufacture the lens system even if the eighth lens L8 becomes too thin. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (22) . It is further desirable that (Nd8) is 1.73 or less.

Moreover, when (νd1) is 45 or less, because correction of axial chromatic aberration is insufficient, the performance on the axis cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (23) . It is further desirable that (νd1) is 48 or more.

Moreover, when (νd2) is 35 or more, because correction of the entire chromatic aberration is insufficient, the performance cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (24) .

Moreover, when (νd6) is 65 or more, because correction of the entire chromatic aberration is insufficient, the performance cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (25) . It is further desirable that (νd6) is 60 or less.

Moreover, when (νd7) is 60 or more, because correction of the entire chromatic aberration is insufficient, the performance cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (26) .

Moreover, when (νd8) is 60 or more, because correction of the entire chromatic aberration is insufficient, the performance cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (27) .

Moreover, when TTL/ImgH is 2.5 or more, because the total track length of the lens becomes too large, the product size becomes large and a merit becomes small. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (28) . It is desirable that TTL/ImgH is 2.0 or less because balance between size and optical performance is kept.

Moreover, when TTL/FL is 0.5 or less, because the total track length of the lens becomes too small, the optical performance cannot be balanced. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (29) . It is further desirable that TTL/FL is 1.0 or more.

Moreover, when TTL/BFL is 5 or less, because the flange focal length of the lens becomes too long, it is disadvantageous for the shortening of the total track length of the lens. For that reason, as indicated in Tables 1 to 8, it is desirable that the imaging lens assembly 2 according to the present embodiment satisfies the conditional expression indicated by the above Expression (30) . It is further desirable that TTL/BFL is 6 or more.

FIGS. 50 and 51 are diagrams explaining examples of a switching process of a background blur amount in the imaging device according to the present embodiment. For example, in the imaging device according to the present embodiment, when Fno is 1.48, because a background blur (blurring) becomes stronger as it moves from an object to a peripheral image (background image) , it is possible to obtain a captured image in which a main object (subject) stands out, as illustrated in FIG. 50. On the other hand, in the imaging device according to the present embodiment, when Fno is reduced to 3.0, it is possible to improve resolution of a background image (surrounding picture) as illustrated in FIG. 51.

As described above, according to the imaging device of the present embodiment, because a background blur effect can be changed in accordance with a demand of the user, it is possible to obtain an optimum background blur effect when performing portrait shooting or macro shooting, and it is possible to improve resolution of a background image when a blurred background is not desired.

[Explanations of Letters or Numerals]

1 imaging device

1a adjustable diaphragm

1b aperture diaphragm

2 imaging lens assembly

3 optical filter

4 image sensor

11 camera module

13 image processing unit

24 board

L1 first lens

L2 second lens

L3 third lens

L4 fourth lens

L5 fifth lens

L6 sixth lens

L7 seventh lens

L8 eighth lens

Claims

An imaging lens assembly comprising:

an optical system including: in order from an object side to an image side,

two aperture diaphragms of an adjustable diaphragm and an aperture diaphragm, a diameter of the adjustable diaphragm not regulating a maximum diameter, and a diameter of the aperture diaphragm regulating the maximum diameter; and

eight lenses,

the eight lenses of the optical system including: in order from the object side,

a first lens that has positive refractive power and whose object-side surface has a convex shape and image-side surface has a concave shape near a paraxial area;

a second lens that has negative refractive power;

a third lens that has positive refractive power;

a fourth lens;

a fifth lens;

a sixth lens;

a seventh lens; and

an eighth lens that has negative refractive power and whose image-side surface has a concave shape, wherein

the imaging lens assembly satisfies the following conditional expressions:

Fno_min < 2.4, wherein Fno_min: Fno at a maximum diameter;

HFOV > 30, wherein HFOV: a half angle of view corresponding to an effective pixel area of an imaging surface of the optical system;

FL/Fno_min/ ( (18*FL/ImgH*21.63) /FL-1) > 0.085; and

FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) < 0.080, wherein FL: a focal length of the optical system, Fno_max: Fno at a minimum diameter, and ImgH: a half-diagonal length of the effective pixel area of the imaging surface of the optical system.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

F1/FL > 0;

F2/FL < 0;

F3/FL > 0;

F1/F8 < 0; and

0.5 < (F _L1-L5) /FL < 2.0, wherein

FL: a focal length of the optical system,

F1: a focal length of the first lens,

F2: a focal length of the second lens,

F3: a focal length of the third lens,

F8: a focal length of the eighth lens, and

(F _L1-L5) : a composite focal length from the first lens to the fifth lens.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expression:

15 < Σ|F (i) /FL| < 500, wherein

F (i) : a focal length of an i-th lens among the first to eighth lenses.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expression:

Σ|Ri/FL| > 10, wherein

Ri: a curvature radius of a lens surface of an i-th lens from the object side of the optical system among the first to eighth lenses.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

1.0 < TTL/ (D _L1-L5) < 3.0; and

TTL/ (D8) > 30, wherein

TTL: a distance from an object-side surface on an optical axis of the first lens to a focus position of the optical system,

(D _L1-L5) : a distance from the object-side surface on the optical axis of the first lens to an image-side surface on the optical axis of the fifth lens, and

(D8) : a distance from an image-side surface on the optical axis of the fourth lens to an object-side surface on the optical axis of the fifth lens.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

R2/R1 > 0;

R3/R4 > 0; and

R6/R5 > 0, wherein

R1: a curvature radius of an object-side surface of the first lens,

R2: a curvature radius of an image-side surface of the first lens,

R3: a curvature radius of an object-side surface of the second lens,

R4: a curvature radius of an image-side surface of the second lens,

R5: a curvature radius of an object-side surface of the third lens, and

R6: a curvature radius of an image-side surface of the third lens.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

R7/R11 > 0; and

R14/R13 > 0, wherein

R7: a curvature radius of an object-side surface of the fourth lens,

R11: a curvature radius of an object-side surface of the sixth lens,

R13: a curvature radius of an object-side surface of the seventh lens, and

R14: a curvature radius of an image-side surface of the seventh lens.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

(Nd2) < 1.75;

(Nd4) < 1.75;

(Nd5) < 1.75;

(Nd8) < 1.75;

(νd1) > 45;

(νd2) < 35;

(νd6) < 65;

(νd7) < 60; and

(νd8) < 60, wherein

(Nd2) : a refractive index of d-line of the second lens,

(Nd4) : a refractive index of d-line of the fourth lens,

(Nd5) : a refractive index of d-line of the fifth lens,

(Nd8) : a refractive index of d-line of the eighth lens,

(νd1) : an Abbe number of the first lens,

(νd2) : an Abbe number of the second lens,

(νd6) : an Abbe number of the sixth lens,

(νd7) : an Abbe number of the seventh lens, and

(νd8) : an Abbe number of the eighth lens.
The imaging lens assembly according to claim 1, wherein

the imaging lens assembly satisfies the following conditional expressions:

TTL/ImgH < 2.5;

TTL/FL > 0.5; and

TTL/BFL > 5, wherein

TTL: a distance from an object-side surface vertex on an optical axis of the first lens to a focus position of the optical system,

ImgH: a half-diagonal length of the effective pixel area of the imaging surface of the optical system, and

BFL: a distance from an ICRF front surface to an image surface.
The imaging lens assembly according to claim 1, wherein a lens on a most image side among the first to eighth lenses is formed of aspherical plastic having an inflection point.
A camera module comprising:

an imaging lens assembly; and

an imaging element configured to output an imaging signal according to an optical image formed by the imaging lens assembly,

the imaging lens assembly comprising an optical system including: in order from an object side to an image side,

two aperture diaphragms of an adjustable diaphragm and an aperture diaphragm, a diameter of the adjustable diaphragm not regulating a maximum diameter, and a diameter of the aperture diaphragm regulating the maximum diameter; and

eight lenses,

the eight lenses of the optical system including: in order from the object side,

a first lens that has positive refractive power and whose object-side surface has a convex shape and image-side surface has a concave shape near a paraxial area;

a second lens that has negative refractive power;

a third lens that has positive refractive power;

a fourth lens;

a fifth lens;

a sixth lens;

a seventh lens; and

an eighth lens that has negative refractive power and whose image-side surface has a concave shape, wherein

the camera module satisfies the following conditional expressions:

Fno_min < 2.4, wherein Fno_min: Fno at a maximum diameter;

HFOV > 30, wherein HFOV: a half angle of view corresponding to an effective pixel area of an imaging surface of the optical system;

FL/Fno_min/ ( (18*FL/ImgH*21.63) /FL-1) > 0.085; and

FL/Fno_max/ ( (18*FL/ImgH*21.63) /FL-1) < 0.080, wherein FL: a focal length of the optical system, Fno_max: Fno at a minimum diameter, and ImgH: a half-diagonal length of the effective pixel area of the imaging surface of the optical system.
An imaging device comprising the camera module according to claim 11.