Optical image capturing system

Abstract

The optical image capturing system includes: a first lens having a positive refractive power, a convex object-side surface, and a concave image-side surface; a second lens having a negative refractive power, a convex object-side surface, and a concave image-side surface; a third lens having a negative refractive power, a convex object-side surface, and a concave image-side surface; a fourth lens having positive refractive power, a convex object-side surface, and a convex image-side surface; a fifth lens having refractive power; a sixth lens having refractive power; and a seventh lens having a negative refractive power, in which the first to seventh lenses are sequentially disposed in a digital ascending order along an optical axis of the optical imaging system from an object side of the optical imaging system toward an imaging surface of the image sensor, in which the optical imaging system has seven lenses in total, and a conditional expression-0.89 < = f / f2 + f / f3lt is satisfied; -0.4, where f is the focal length of the optical imaging system, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2019-0020453, filed with the Korean Intellectual Property Office on February 21, 2019, and Korean Patent Application No. 10-2019-0091493, filed with the Korean Intellectual Property Office on July 29, 2019, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0003] This application relates to optical imaging systems. Background Technology

[0004] Recently, portable terminal devices have been designed to include cameras to allow for video calls and image capture. Furthermore, with the frequent use of camera functionality in portable terminal devices, the demand for high-resolution and high-performance cameras in these devices is constantly increasing.

[0005] However, with the size and weight of portable terminals already reduced, there are difficulties in realizing cameras with high resolution and high performance.

[0006] To address these issues, plastic materials, which are lighter than glass, have been used to manufacture camera lenses, and optical imaging systems have been designed to include five or six lenses to achieve high resolution. Summary of the Invention

[0007] The summary portion of this invention is intended to provide a brief overview of the chosen inventive concepts, which will be further described in the detailed description portion below. This summary portion is not intended to identify key or essential features of the claimed subject matter, nor to help determine the scope of the claimed subject matter.

[0008] In one general aspect, the optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in ascending numerical order along the optical axis of the optical imaging system from the object side of the optical imaging system toward the imaging surface of the image sensor, wherein the conditional expression f / f2+f / f3 < -0.4 can be satisfied, where f is the focal length of the optical imaging system, f2 is the focal length of the second lens, and f3 is the focal length of the third lens, and the conditional expression TTL / (2×IMG HT) < 0.69 can be satisfied, where TTL is the distance along the optical axis from the object side of the first lens to the imaging surface of the image sensor, and IMG HT is half the diagonal length of the imaging surface of the image sensor.

[0009] A conditional expression n2+n3>3.15 can be satisfied, where n2 is a refractive index of the second lens, and n3 is a refractive index of the third lens.

[0010] A conditional expression n2+n3+n4>4.85 can be satisfied, where n4 is a refractive index of the fourth lens.

[0011] A conditional expression v1-v2>30 can be satisfied, where v1 is an Abbe number of the first lens, and v2 is an Abbe number of the second lens.

[0012] A conditional expression 1.0

[0013] A conditional expression 0.15

[0014] A conditional expression 0.005

[0015] A conditional expression 0.30

[0016] A conditional expression 1.4

[0017] A conditional expression Fno<2.3 can be satisfied, where Fno is an F number of the optical imaging system.

[0018] A refractive index of each of at least two lenses among the first lens to the seventh lens can be 1.67 or more.

[0019] The first lens can have a positive refractive power, either one or both of the second lens and the third lens can have a negative refractive power, and a refractive index of each of the either one or both of the second lens and the third lens can be 1.67 or more.

[0020] The first lens can have a positive refractive power, and the seventh lens can have a negative refractive power.

[0021] In another general aspect, an optical imaging system includes, in order along an optical axis of the optical imaging system from an object side of the optical imaging system toward an imaging surface of an image sensor, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, wherein the first lens has a positive refractive power, and either one or both of the second lens and the third lens has a negative refractive power, a condition expression n2+n3 > 3.15 is satisfied, where n2 is a refractive index of the second lens and n3 is a refractive index of the third lens, and a condition expression TTL / (2xIMG HT) < 0.69 is satisfied, where TTL is a distance along the optical axis from an object side surface of the first lens to the imaging surface of the image sensor, and IMG HT is half of a diagonal length of the imaging surface of the image sensor.

[0022] A condition expression f / f2+f / f3 < -0.4 can be satisfied, where f is a focal length of the optical imaging system, f2 is a focal length of the second lens, and f3 is a focal length of the third lens.

[0023] A condition expression v1-v2 > 30 and n2+n3+n4 > 4.85 can be satisfied, where v1 is an Abbe number of the first lens, v2 is an Abbe number of the second lens, and n4 is a refractive index of the fourth lens.

[0024] Other features and aspects will become apparent from the following detailed description, drawings and claims. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a diagram illustrating a first example of an optical imaging system.

[0026] Figure 2 FIG. 2 is a diagram illustrating aberration characteristics of the optical imaging system illustrated in FIG. 1. Figure 1

[0027] Figure 3 FIG. 3 is a diagram illustrating a second example of an optical imaging system.

[0028] Figure 4 FIG. 4 is a diagram illustrating aberration characteristics of the optical imaging system illustrated in FIG. 3. Figure 3

[0029] Figure 5 FIG. 5 is a diagram illustrating a third example of an optical imaging system.

[0030] Figure 6 FIG. 6 is a diagram illustrating aberration characteristics of the optical imaging system illustrated in FIG. 5. Figure 5

[0031] Figure 7 FIG. 7 is a diagram illustrating a fourth example of an optical imaging system.​​​

[0032] Figure 8 is a graph showing aberration characteristics of the optical imaging system shown in Figure 7

[0033] Figure 9 is a graph showing aberration characteristics of the optical imaging system shown in

[0034] Figure 10 is a graph showing aberration characteristics of the optical imaging system shown in Figure 9

[0035] Throughout the drawings and specific embodiments, identical reference numerals designate identical elements, for the purposes of clarity, illustration and convenience, the drawings can not be to scale, and the relative dimensions, proportions and depiction of elements in the drawings can be exaggerated for illustrative purposes. DETAILED DESCRIPTION

[0036] The following detailed description is presented to aid the reader in gaining a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, various changes, modifications, and equivalents can be used, and the

[0037] The features described herein can be implemented in different forms and should not be construed as limited to the examples described herein. Rather, these examples are provided as illustration only so that those skilled in the art will understand the many possible ways in which the methods, apparatuses, and / or systems described herein can be implemented.

[0038] The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the disclosure. Unless otherwise defined, the adjectives "one" and "the" are intended to encompass both the singular and the plural. The phrase "comprising" or "including" means that the features, numbers, operations, components, elements, and / or combinations thereof described are present, but does not exclude the presence or addition of one or more other features, numbers, operations, components, elements, and / or combinations thereof.

[0039] In the drawings, the thickness, size, and shape of each lens of the optical imaging system can be exaggerated for ease of explanation, and the spherical shape or aspherical shape shown in the drawings is merely an example, and the shape is not limited thereto. ​​

[0040] The first lens of the optical imaging system is a lens closest to an object side of the optical imaging system, and the seventh lens of the optical imaging system is a lens closest to an image sensor of the optical imaging system.

[0041] The first surface (or object side surface) of the lens is a surface facing the object side of the optical imaging system, and the second surface (or image side surface) of the lens is a surface facing the image sensor.

[0042] The radius of curvature of the surface of the element, the thickness of the element, the distance between the elements, the distance between the surface of one element and the surface of another element, the focal length, the image height (IMG HT) are expressed in millimeters (mm), and the field of view angle (FOV) is expressed in degrees. The thickness and the distance are measured along the optical axis of the optical imaging system.

[0043] The expression that the surface of the lens is convex means that at least the paraxial region of the surface is convex, the expression that the surface of the lens is concave means that at least the paraxial region of the surface is concave, and the expression that the surface of the lens is flat means that at least the paraxial region of the surface is flat. Therefore, even when the surface of the lens is described as convex, the edge region of the surface can be concave. In addition, even when the surface of the lens is described as concave, the edge region of the surface can be convex. In addition, even when the surface of the lens is described as flat, the edge region of the surface can be convex or concave.

[0044] The paraxial region of the surface of the lens is a central portion of the surface of the lens around the optical axis of the surface of the lens, in which the angle between the light ray incident to the surface of the lens and the optical axis is a small angle θ, and the approximations sin θ ≈ θ, tan θ ≈ θ, and cos θ ≈ 1 are valid.

[0045] The optical imaging system can include seven lenses.

[0046] For example, the optical imaging system can include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in a numerical ascending order along the optical axis of the optical imaging system from the object side of the optical imaging system toward the image side of the optical imaging system. The first lens to the seventh lens can be disposed to have a predetermined distance along the optical axis therebetween.

[0047] However, in addition to the seven lenses, the optical imaging system can include other elements.

[0048] For example, the optical imaging system can further include an image sensor for converting an incident image of an object into an electrical signal.

[0049] In addition, the optical imaging system can further include an infrared filter (hereinafter, referred to as a "filter") for blocking infrared rays. The filter can be disposed between the seventh lens and the image sensor.

[0050] Additionally, the optical imaging system can further include a diaphragm for adjusting an amount of light incident onto the image sensor. The diaphragm can be disposed at any desired location.

[0051] The first lens through the seventh lens included in the optical imaging system can be made of a plastic material.

[0052] Any one or any combination of two or more of the first lens through the seventh lens can have an aspherical surface. Alternatively, each of the first lens through the seventh lens can have at least one aspherical surface.

[0053] Either one or both of the first face and the second face of each of the first lens through the seventh lens can be an aspherical surface defined by the following Equation 1.

[0054] (1)

[0055] In Equation 1, "c" is a curvature of the aspherical surface at an optical axis of the aspherical surface and is equal to an inverse of a radius of curvature of the aspherical surface at the optical axis, "K" is a conic constant, "Y" is a distance from an arbitrary point on the aspherical surface to the optical axis in a direction perpendicular to the optical axis, "A" through "H" and "J" are aspherical coefficients of the aspherical surface, and "Z" is a distance from the arbitrary point on the aspherical surface to a plane perpendicular to the optical axis and containing a vertex of the aspherical surface in a direction parallel to the optical axis.

[0056] In one example, the first lens through the seventh lens can have positive refractive power, negative refractive power, positive refractive power, positive refractive power, positive refractive power, positive refractive power, and negative refractive power, respectively.

[0057] In another example, the first lens through the seventh lens can have positive refractive power, positive refractive power, negative refractive power, positive refractive power, positive refractive power, positive refractive power, and negative refractive power, respectively.

[0058] In another example, the first lens through the seventh lens can have positive refractive power, negative refractive power, negative refractive power, positive refractive power, positive refractive power, positive refractive power, and negative refractive power, respectively.

[0059] In another example, the first lens through the seventh lens can have positive refractive power, negative refractive power, negative refractive power, positive refractive power, positive refractive power, negative refractive power, and negative refractive power, respectively.

[0060] In another example, the first lens through the seventh lens can have positive refractive power, negative refractive power, positive refractive power, negative refractive power, negative refractive power, positive refractive power, and negative refractive power, respectively.

[0061] Examples of the optical imaging system can satisfy any one or any combination of any group of the following conditional expressions 1 to 11.

[0062] f / f2 + f / f3 < -0.4 (Conditional expression 1)

[0063] v1-v2 > 30 (Conditional expression 2)

[0064] 1.0 < TTL / f < 1.10 (Conditional expression 3)

[0065] n2+n3 > 3.15 (Conditional expression 4)

[0066] 0.15 < BFL / f < 0.25 (Conditional expression 5)

[0067] 0.005 < D1 / f < 0.04 (Conditional expression 6)

[0068] 0.30 < R1 / f < 0.40 (Conditional expression 7)

[0069] TTL / (2xIMG HT) < 0.69 (Conditional expression 8)

[0070] Fno < 2.3 (Conditional expression 9)

[0071] n2+n3+n4 > 4.85 (Conditional expression 10)

[0072] 1.4 < |f23| / f1 < 2.8 (Conditional expression 11)

[0073] In the conditional expressions 1 to 11, “f” is a focal length of the optical imaging system, “f1” is a focal length of the first lens, “f2” is a focal length of the second lens, “f3” is a focal length of the third lens, “f23” is a combined focal length of the second lens and the third lens, “v1” is an Abbe number of the first lens, “v2” is an Abbe number of the second lens, “TTL” is a distance along an optical axis of the optical imaging system from an object side surface of the first lens to an imaging surface of an image sensor, “n2” is a refractive index of the second lens, “n3” is a refractive index of the third lens, “n4” is a refractive index of the fourth lens, “BFL” is a distance along the optical axis from an image side surface of the seventh lens to the imaging surface of the image sensor, “D1” is a distance along the optical axis between the image side surface of the first lens and the object side surface of the second lens, “R1” is a radius of curvature of the object side surface of the first lens, “IMG HT” is half of a diagonal length of the imaging surface of the image sensor, and “Fno” is an F number of the optical imaging system.

[0074] In the following description, the first to seventh lenses in an example of an optical imaging system will be described.

[0075] The first lens can have a positive refractive power. The first lens can have a meniscus shape convex toward an object side of the optical imaging system. In other words, the first face of the first lens can be convex, and the second face of the first lens can be concave.

[0076] Either one or both of the first and second faces of the first lens can be aspherical. For example, both faces of the first lens can be aspherical.

[0077] The second lens can have a positive refractive power or a negative refractive power. The second lens can have a meniscus shape convex toward an object side of the optical imaging system. In other words, the first face of the second lens can be convex, and the second face of the second lens can be concave.

[0078] Either one or both of the first and second faces of the second lens can be aspherical. For example, both faces of the second lens can be aspherical.

[0079] The third lens can have a positive refractive power or a negative refractive power. The third lens can have a meniscus shape convex toward an object side of the optical imaging system. In other words, the first face of the third lens can be convex, and the second face of the third lens can be concave.

[0080] Either one or both of the first and second faces of the third lens can be aspherical. For example, both faces of the third lens can be aspherical.

[0081] At least one inflection point can be formed on either one or both of the first and second faces of the third lens. For example, the first face of the third lens can be convex in a paraxial region of the first face, and concave in an edge region of the first face.

[0082] The fourth lens can have a positive refractive power or a negative refractive power. The fourth lens can have a meniscus shape convex toward an object side of the optical imaging system. In other words, the first face of the fourth lens can be convex, and the second face of the fourth lens can be concave.

[0083] Alternatively, the first face of the fourth lens can be flat in a paraxial region of the first face, and the second face can be convex.

[0084] Alternatively, both faces of the fourth lens can be convex. In other words, the first and second faces of the fourth lens can be convex.

[0085] Either one or both of the first and second faces of the fourth lens can be aspherical. For example, both faces of the fourth lens can be aspherical.

[0086] At least one inflection point can be formed on either or both of the first and second surfaces of the fourth lens. For example, the second surface of the fourth lens can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0087] The fifth lens can have a positive or negative refractive power. The fifth lens can have a meniscus shape convex toward the object side of the optical imaging system. In other words, the first surface of the fifth lens can be convex in the paraxial region of the first surface and the second surface of the fifth lens can be concave.

[0088] Alternatively, both surfaces of the fifth lens can be convex. In other words, the first and second surfaces of the fifth lens can be convex.

[0089] Alternatively, both surfaces of the fifth lens can be concave. In other words, the first and second surfaces of the fifth lens can be concave.

[0090] Either or both of the first and second surfaces of the fifth lens can be aspherical. For example, both surfaces of the fifth lens can be aspherical.

[0091] At least one inflection point can be formed on either or both of the first and second surfaces of the fifth lens. For example, the first surface of the fifth lens can be convex in the paraxial region of the first surface and concave in the peripheral region of the first surface. The second surface of the fifth lens can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0092] The sixth lens can have a positive or negative refractive power. Both surfaces of the sixth lens can be convex. In other words, the first and second surfaces of the sixth lens can be convex in the paraxial regions of the first and second surfaces, respectively.

[0093] The sixth lens can have a meniscus shape convex toward the image side of the optical imaging system. In other words, the first surface of the sixth lens can be concave in the paraxial region of the first surface and the second surface of the sixth lens can be convex in the paraxial region of the second surface.

[0094] Alternatively, the sixth lens can have a meniscus shape convex toward the object side of the optical imaging system. In other words, the first surface of the sixth lens can be convex in the paraxial region of the first surface and the second surface of the sixth lens can be concave in the paraxial region of the second surface.

[0095] Either or both of the first and second surfaces of the sixth lens can be aspherical. For example, both surfaces of the sixth lens can be aspherical.

[0096] At least one inflection point can be formed on either one or both of the first and second surfaces of the sixth lens. For example, the first surface of the sixth lens can be convex in the paraxial region of the first surface and concave in the peripheral region of the first surface. The second surface of the sixth lens can be convex in the paraxial region of the second surface and concave in the peripheral region of the second surface.

[0097] The seventh lens can have a negative refractive power. Both of the first and second surfaces of the seventh lens can be concave. In other words, the first surface of the seventh lens can be concave in the paraxial region of the first surface and the second surface of the seventh lens can be concave in the paraxial region of the second surface.

[0098] Alternatively, the seventh lens can have a meniscus shape convex toward the object side of the optical imaging system. In other words, the first surface of the seventh lens can be convex in the paraxial region of the first surface and the second surface of the seventh lens can be concave in the paraxial region of the second surface.

[0099] Either one or both of the first and second surfaces of the seventh lens can be aspherical. For example, both of the first and second surfaces of the seventh lens can be aspherical.

[0100] At least one inflection point can be formed on either one or both of the first and second surfaces of the seventh lens. For example, the first surface of the seventh lens can be concave in the paraxial region of the first surface and convex in the peripheral region of the first surface. The second surface of the seventh lens can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0101] The first lens can be made of a first plastic material, and the second lens can be made of a second plastic material having optical properties different from the optical properties of the first plastic material.

[0102] The refractive index of at least one lens among the first to seventh lenses can be 1.67 or more.

[0103] In addition, the refractive index of each of at least two lenses among the first to seventh lenses can be 1.67 or more. For example, in one example, the refractive index of each of three lenses among the first to seventh lenses can be 1.67 or more, and in another example, the refractive index of each of two lenses among the first to seventh lenses can be 1.67 or more.

[0104] The refractive index of a lens having a negative refractive power among the first to third lenses can be 1.67 or more. As an example, either one or both of the second and third lenses can have a negative refractive power and can have a refractive index of 1.67 or more.

[0105] An example of an optical imaging system having the first lens to the seventh lens configured as described above has improved aberration characteristics.

[0106] Figure 1 is a diagram showing a first example of an optical imaging system, and Figure 2 is a diagram showing Figure 1 aberration characteristics of the optical imaging system shown in

[0107] The optical imaging system of the first example can include the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160, and the seventh lens 170, and can further include a stop (not shown), a filter 180, and an image sensor 190.

[0108] Features of the elements shown in Figure 1 including a radius of curvature of a surface of the element, a thickness of the element, a distance between the elements, a refractive index of the element, an Abbe number of the element, and a focal length of the element, are listed in Table 1 below.

[0109] Table 1

[0110] In the first example, a focal length f of the optical imaging system is 5.744 mm, an Fno is 2.01, a FOV is 77.23°, a BFL is 0.909 mm, a TTL is 6.201 mm, and an IMG HT is 4.56 mm.

[0111] The Fno is a value representing a brightness of the optical imaging system, and is equal to an effective focal length of the optical imaging system divided by an entrance pupil diameter of the optical imaging system, the FOV is a field of view angle of the optical imaging system, the BFL is a distance along an optical axis of the optical imaging system from an image side surface of the seventh lens to an imaging surface of the image sensor, the TTL is a distance along the optical axis from an object side surface of the first lens to the imaging surface of the image sensor, and the IMG HT is half of a diagonal length of the imaging surface of the image sensor.

[0112] In the first example, the first lens 110 can have a positive refractive power, a first surface of the first lens 110 can be convex, and a second surface of the first lens 110 can be concave.

[0113] The second lens 120 can have a negative refractive power, a first surface of the second lens 120 can be convex, and a second surface of the second lens 120 can be concave.

[0114] The third lens 130 can have a positive refractive power, a first surface of the third lens 130 can be convex in a paraxial region of the first surface, and a second surface of the third lens 130 can be concave in a paraxial region of the second surface.

[0115] At least one inflection point can be formed on either one or both of the first and second surfaces of the third lens 130. For example, the first surface of the third lens 130 can be convex in the paraxial region of the first surface and concave in the peripheral region of the first surface. The second surface of the third lens 130 can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0116] The fourth lens 140 can have a positive refractive power, the first surface of the fourth lens 140 can be convex, and the second surface of the fourth lens 140 can be concave.

[0117] The fifth lens 150 can have a positive refractive power, the first surface of the fifth lens 150 can be convex in the paraxial region of the first surface, and the second surface of the fifth lens 150 can be concave in the paraxial region of the second surface.

[0118] At least one inflection point can be formed on either one or both of the first and second surfaces of the fifth lens 150. For example, the first surface of the fifth lens 150 can be convex in the paraxial region of the first surface and concave in the peripheral region of the first surface. The second surface of the fifth lens 150 can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0119] The sixth lens 160 can have a positive refractive power, and the first and second surfaces of the sixth lens 160 can be convex.

[0120] At least one inflection point can be formed on either one or both of the first and second surfaces of the sixth lens 160. For example, the first surface of the sixth lens 160 can be convex in the paraxial region of the first surface and concave in the peripheral region of the first surface. The second surface of the sixth lens 160 can be convex in the paraxial region of the second surface and concave in the peripheral region of the second surface.

[0121] The seventh lens 170 can have a negative refractive power, the first surface of the seventh lens 170 can be concave in the paraxial region of the first surface, and the second surface of the seventh lens 170 can be concave in the paraxial region of the second surface.

[0122] At least one inflection point can be formed on either one or both of the first and second surfaces of the seventh lens 170. For example, the first surface of the seventh lens 170 can be concave in the paraxial region of the first surface and convex in the peripheral region of the first surface. The second surface of the seventh lens 170 can be concave in the paraxial region of the second surface and convex in the peripheral region of the second surface.

[0123] The surfaces of the first to seventh lenses 110 to 170 can have aspheric coefficients listed in Table 2 below. For example, each of the object side surface and the image side surface of each of the first to seventh lenses 110 to 170 can be aspheric.

[0124] Table 2

[0125] Figure 1 The first example of the optical imaging system shown in FIG. 1A configured according to the above Table 1 and Table 2 can have Figure 2 aberration characteristics shown in FIG. 2A.

[0126] Figure 3 is a graph showing aberration characteristics of the optical imaging system shown in FIG. 1A. Figure 4 is a graph showing Figure 3 aberration characteristics of the optical imaging system shown in FIG. 2A.

[0127] The optical imaging system of the second example can include a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, a sixth lens 260, and a seventh lens 270, and can further include a stop (not shown), a filter 280, and an image sensor 290.

[0128] The characteristics of the elements shown in FIG. 3A, including the radius of curvature of the surface of the element, the thickness of the element, the distance between the elements, the refractive index of the element, the Abbe number of the element, and the focal length of the element, are listed in Table 3 below. Figure 3

[0129] Table 3

[0130] In the second example, the focal length f of the optical imaging system is 6.000 mm, the Fno is 2.18, the FOV is 72.96°, the BFL is 0.908 mm, the TTL is 6.202 mm, and the IMG HT is 4.56 mm.

[0131] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0132] In the second example, the first lens 210 can have a positive refractive power, the first surface of the first lens 210 can be convex, and the second surface of the first lens 210 can be concave.

[0133] The second lens 220 can have a positive refractive power, the first surface of the second lens 220 can be convex, and the second surface of the second lens 220 can be concave.

[0134] ​The third lens 230 can have a negative refractive power, a first surface of the third lens 230 can be convex, and a second surface of the third lens 230 can be concave.

[0135] The fourth lens 240 can have a positive refractive power, a first surface of the fourth lens 240 can be convex in a paraxial region of the first surface, and a second surface of the fourth lens 240 can be concave in a paraxial region of the second surface.

[0136] At least one inflection point can be formed on either one or both of the first and second surfaces of the fourth lens 240. For example, the first surface of the fourth lens 240 can be convex in a paraxial region of the first surface and concave in an edge region of the first surface. The second surface of the fourth lens 240 can be concave in a paraxial region of the second surface and convex in an edge region of the second surface.

[0137] The fifth lens 250 can have a positive refractive power, a first surface of the fifth lens 250 can be convex in a paraxial region of the first surface, and a second surface of the fifth lens 250 can be concave in a paraxial region of the second surface.

[0138] At least one inflection point can be formed on either one or both of the first and second surfaces of the fifth lens 250. For example, the first surface of the fifth lens 250 can be convex in a paraxial region of the first surface and concave in an edge region of the first surface. The second surface of the fifth lens 250 can be concave in a paraxial region of the second surface and convex in an edge region of the second surface.

[0139] The sixth lens 260 can have a positive refractive power, a first surface of the sixth lens 260 can be convex in a paraxial region of the first surface, and a second surface of the sixth lens 260 can be convex in a paraxial region of the second surface.

[0140] At least one inflection point can be formed on either one or both of the first and second surfaces of the sixth lens 260. For example, the first surface of the sixth lens 260 can be convex in a paraxial region of the first surface and concave in an edge region of the first surface. The second surface of the sixth lens 260 can be convex in a paraxial region of the second surface and concave in an edge region of the second surface.

[0141] The seventh lens 270 can have a negative refractive power, a first surface of the seventh lens 270 can be concave in a paraxial region of the first surface, and a second surface of the seventh lens 270 can be concave in a paraxial region of the second surface.

[0142] At least one inflection point can be formed on either or both of the first and second faces of the seventh lens 270. For example, the first face of the seventh lens 270 can be concave in the paraxial region of the first face and convex in the edge region of the first face. The second face of the seventh lens 270 can be concave in the paraxial region of the second face and convex in the edge region of the second face.

[0143] The surfaces of the first lens 210 through the seventh lens 270 can have the aspheric coefficients listed in Table 4 below. For example, each of the object side face and the image side face of each of the first lens 210 through the seventh lens 270 can be aspheric.

[0144] Table 4

[0145] Figure 3 The second example of the optical imaging system configured according to the above Table 3 and Table 4 shown in FIG. 2 can have Figure 4 aberration characteristics shown in FIG. 3.

[0146] Figure 5 is a graph showing a third example of an optical imaging system, and Figure 6 is a graph showing Figure 5 aberration characteristics of the optical imaging system shown in FIG. 4.

[0147] The optical imaging system of the third example can include a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, a sixth lens 360, and a seventh lens 370, and can further include a stop, a filter 380, and an image sensor 390.

[0148] The characteristics of the elements shown in FIG. 5 below are listed in Table 5 below, including the radius of curvature of the surface of the element, the thickness of the element, the distance between the elements, the refractive index of the element, the Abbe number of the element, and the focal length of the element. Figure 5

[0149] Table 5

[0150] In the third example, the focal length f of the optical imaging system is 6.000 mm, the Fno is 2.14, the FOV is 73.59°, the BFL is 1.234 mm, the TTL is 6.200 mm, and the IMG HT is 4.56 mm.

[0151] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0152] ​In a third example, the first lens 310 can have a positive refractive power, a first surface of the first lens 310 can be convex, and a second surface of the first lens 310 can be concave.

[0153] The second lens 320 can have a negative refractive power, a first surface of the second lens 320 can be convex, and a second surface of the second lens 320 can be concave.

[0154] The third lens 330 can have a negative refractive power, a first surface of the third lens 330 can be convex in a paraxial region of the first surface, and a second surface of the third lens 330 can be concave in a paraxial region of the second surface.

[0155] At least one inflection point can be formed on either or both of the first and second surfaces of the third lens 330. For example, the first surface of the third lens 330 can be convex in a paraxial region of the first surface, and concave in a peripheral region of the first surface. The second surface of the third lens 330 can be concave in a paraxial region of the second surface, and convex in a peripheral region of the second surface.

[0156] The fourth lens 340 can have a positive refractive power, a first surface of the fourth lens 340 can be flat in a paraxial region of the first surface, and a second surface of the fourth lens 340 can be convex in a paraxial region of the second surface.

[0157] At least one inflection point can be formed on either or both of the first and second surfaces of the fourth lens 340. For example, the first surface of the fourth lens 340 can be flat in a paraxial region of the first surface, and convex in a peripheral region of the first surface.

[0158] The fifth lens 350 can have a positive refractive power, and the first and second surfaces of the fifth lens 350 can be convex.

[0159] The sixth lens 360 can have a positive refractive power, a first surface of the sixth lens 360 can be concave, and a second surface of the sixth lens 360 can be convex.

[0160] The seventh lens 370 can have a negative refractive power, a first surface of the seventh lens 370 can be concave in a paraxial region of the first surface, and a second surface of the seventh lens 370 can be concave in a paraxial region of the second surface.

[0161] At least one inflection point can be formed on either or both of the first and second surfaces of the seventh lens 370. For example, the first surface of the seventh lens 370 can be concave in a paraxial region of the first surface, and convex in a peripheral region of the first surface. The second surface of the seventh lens 370 can be concave in a paraxial region of the second surface, and convex in a peripheral region of the second surface.

[0162] The surfaces of the first to seventh lenses 310 to 370 can have aspheric coefficients listed in Table 6 below. For example, each of the object side surface and the image side surface of each of the first to seventh lenses 310 to 370 can be aspheric.

[0163] Table 6

[0164] Figure 5 The third example of the optical imaging system shown in FIG. 13A can have the aberration characteristics according to the configuration of the above Tables 5 and 6. Figure 6

[0165] Figure 7 is a graph showing the aberration characteristics of the optical imaging system shown in FIG. 13A. Figure 8 Figure 7

[0166] The optical imaging system of the fourth example can include a first lens 410, a second lens 420, a third lens 430, a fourth lens 440, a fifth lens 450, a sixth lens 460, and a seventh lens 470, and can further include a stop, a filter 480, and an image sensor 490.

[0167] The characteristics of the elements shown in FIG. 14A are listed in Table 7 below, including the radius of curvature of the surface of the element, the thickness of the element, the distance between the elements, the refractive index of the element, the Abbe number of the element, and the focal length of the element. Figure 7

[0168] Table 7

[0169] In the fourth example, the focal length f of the optical imaging system is 6.000 mm, the Fno is 2.20, the FOV is 74.55°, the BFL is 1.196 mm, the TTL is 6.200 mm, and the IMG HT is 4.56 mm.

[0170] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0171] In the fourth example, the first lens 410 can have a positive refractive power, the first surface of the first lens 410 can be convex, and the second surface of the first lens 410 can be concave.

[0172] The second lens 420 can have a negative refractive power, the first surface of the second lens 420 can be convex, and the second surface of the second lens 420 can be concave.

[0173] ​​​​The third lens 430 can have a negative refractive power, the first surface of the third lens 430 can be convex in a paraxial region of the first surface, and the second surface of the third lens 430 can be concave.

[0174] At least one inflection point can be formed on either or both of the first and second surfaces of the third lens 430. For example, the first surface of the third lens 430 can be convex in a paraxial region of the first surface, and concave in a peripheral region of the first surface.

[0175] The fourth lens 440 can have a positive refractive power, and the first and second surfaces of the fourth lens 440 can be convex.

[0176] The fifth lens 450 can have a positive refractive power, and the first and second surfaces of the fifth lens 450 can be convex.

[0177] The sixth lens 460 can have a negative refractive power, the first surface of the sixth lens 460 can be concave, and the second surface of the sixth lens 460 can be convex.

[0178] The seventh lens 470 can have a negative refractive power, the first surface of the seventh lens 470 can be concave in a paraxial region of the first surface, and the second surface of the seventh lens 470 can be concave in a paraxial region of the second surface.

[0179] At least one inflection point can be formed on either or both of the first and second surfaces of the seventh lens 470. For example, the first surface of the seventh lens 470 can be concave in a paraxial region of the first surface, and convex in a peripheral region of the first surface. The second surface of the seventh lens 470 can be concave in a paraxial region of the second surface, and convex in a peripheral region of the second surface.

[0180] The surfaces of the first through seventh lenses 410-470 can have aspheric coefficients listed in Table 8 below. For example, each of the object and image sides of each of the first through seventh lenses 410-470 can be aspheric.

[0181] Table 8

[0182] Figure 7 A fourth example of the optical imaging system configured according to the above Tables 7 and 8 can have Figure 8 aberration characteristics as shown in FIG. 7.

[0183] Figure 9 is a graph showing a fifth example of an optical imaging system, and Figure 10 is a graph showing Figure 9 aberration characteristics of the optical imaging system shown in FIG. 7.

[0184] The optical imaging system of the fifth example can include the first lens 510, the second lens 520, the third lens 530, the fourth lens 540, the fifth lens 550, the sixth lens 560, and the seventh lens 570, and can further include a stop, a filter 580, and an image sensor 590.

[0185] The characteristics of the elements shown in Table 9 below are listed in Table 10 below, including the radius of curvature of the surface of the element, the thickness of the element, the distance between the elements, the refractive index of the element, the Abbe number of the element, and the focal length of the element. Figure 9

[0186] Table 9

[0187] In the fifth example, the focal length f of the optical imaging system is 5.870 mm, the Fno is 2.27, the FOV is 75.52°, the BFL is 0.965 mm, the TTL is 6.197 mm, and the IMG HT is 4.62 mm.

[0188] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0189] In the fifth example, the first lens 510 can have a positive refractive power, the first surface of the first lens 510 can be convex, and the second surface of the first lens 510 can be concave.

[0190] The second lens 520 can have a negative refractive power, the first surface of the second lens 520 can be convex, and the second surface of the second lens 520 can be concave.

[0191] The third lens 530 can have a positive refractive power, the first surface of the third lens 530 can be convex, and the second surface of the third lens 530 can be concave.

[0192] The fourth lens 540 can have a negative refractive power, the first surface of the fourth lens 540 can be convex in the paraxial region of the first surface, and the second surface of the fourth lens 540 can be concave in the paraxial region of the second surface.

[0193] At least one inflection point can be formed on either one or both of the first and second surfaces of the fourth lens 540. For example, the first surface of the fourth lens 540 can be convex in the paraxial region of the first surface and concave in the edge region of the first surface. The second surface of the fourth lens 540 can be concave in the paraxial region of the second surface and convex in the edge region of the second surface.

[0194] The fifth lens 550 can have a negative refractive power, the first surface of the fifth lens 550 can be concave, and the second surface of the fifth lens 550 can be concave. ​

[0195] The sixth lens 560 can have a positive refractive power, the first surface of the sixth lens 560 can be convex in the paraxial region of the first surface, and the second surface of the sixth lens 560 can be concave in the paraxial region of the second surface.

[0196] At least one inflection point can be formed on either one or both of the first and second surfaces of the sixth lens 560. For example, the first surface of the sixth lens 560 can be convex in the paraxial region of the first surface, and concave in the peripheral region of the first surface. The second surface of the sixth lens 560 can be concave in the paraxial region of the second surface, and convex in the peripheral region of the second surface.

[0197] The seventh lens 570 can have a negative refractive power, the first surface of the seventh lens 570 can be convex in the paraxial region of the first surface, and the second surface of the seventh lens 570 can be concave in the paraxial region of the second surface.

[0198] At least one inflection point can be formed on either one or both of the first and second surfaces of the seventh lens 570. For example, the second surface of the seventh lens 570 can be concave in the paraxial region of the second surface, and convex in the peripheral region of the second surface.

[0199] The surfaces of the first to seventh lenses 510 to 570 can have aspherical coefficients listed in Table 10 below. For example, each of the object side surface and the image side surface of each of the first to seventh lenses 510 to 570 can be aspherical.

[0200] Table 10

[0201] Figure 9 The fifth example of the optical imaging system configured according to the above Tables 9 and 10 shown in the above description can have Figure 10 aberration characteristics shown in the above description.

[0202] Table 11 below lists values of the conditional expressions 1 to 11 in the first to fifth examples.

[0203] Table 11

[0204] According to the above examples, the optical imaging system can have a reduced size and an increased focal length. The increased focal length allows the optical imaging system to have a high resolution.

[0205] While the present disclosure includes specific examples, it will be apparent to one skilled in the art, after an understanding of the disclosure herein, that various changes in form and details can be made without departing from the spirit and scope of the claims and their equivalents. The examples described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects in each example should be considered as being applicable to similar features or aspects in other examples. Suitable results can be achieved if the described techniques are performed in a different order, and / or if the described systems, architectures, devices, or circuits are combined or substituted with other components or their equivalents. Therefore, the scope of the disclosure should not be defined by the specific examples, but should be understood to include any and all variations that are within the scope of the claims and their equivalents.

Claims

1. An optical imaging system, comprising: a first lens having positive refractive power, a convex object side surface, and a concave image side surface; a second lens having negative refractive power, a convex object side surface, and a concave image side surface; a third lens having negative refractive power, a convex object side surface, and a concave image side surface; a fourth lens having positive refractive power, a convex object side surface, and a convex image side surface; a fifth lens having refractive power; a sixth lens having refractive power; and a seventh lens having negative refractive power, wherein the first lens to the seventh lens are sequentially arranged in ascending numerical order along an optical axis of the optical imaging system from an object side of the optical imaging system toward an imaging surface of an image sensor, wherein the optical imaging system has a total of seven lenses, wherein a conditional expression -0.89 ≤ f / f2 + f / f3 < -0.4 is satisfied, where f is a focal length of the optical imaging system, f2 is a focal length of the second lens, and f3 is a focal length of the third lens. a conditional expression 1.4 < |f23| / f1 <2.8 is satisfied, where f1 is a focal length of the first lens, and f23 is a combined focal length of the second lens and the third lens.

2. The optical imaging system of claim 1, wherein, a conditional expression 30 < v1-v2 ≤ 44.35 is satisfied, where v1 is an Abbe number of the first lens, and v2 is an Abbe number of the second lens.

3. The optical imaging system of claim 1, wherein, a conditional expression 3.15 < n2+n3 ≤3.37 is satisfied, where n2 is a refractive index of the second lens, and n3 is a refractive index of the third lens.

4. The optical imaging system of claim 1, wherein, a conditional expression 4.85 < n2+n3+n4 ≤5.04 is satisfied, where n2 is a refractive index of the second lens, n3 is a refractive index of the third lens, and n4 is a refractive index of the fourth lens.

5. The optical imaging system of claim 1, wherein, a conditional expression 0.15 < BFL / f < 0.25 is satisfied, where BFL is a distance along the optical axis from an image side surface of the seventh lens to the imaging surface of the image sensor.

6. The optical imaging system of claim 1, wherein, a conditional expression Fno < 2.3 is satisfied, where Fno is an F number of the optical imaging system.

7. The optical imaging system of claim 1, wherein, a conditional expression 0.005 < D1 / f < 0.04 is satisfied, where f is a focal length of the optical imaging system, and D1 is a distance along the optical axis between an image side surface of the first lens and an object side surface of the second lens.

8. The optical imaging system of claim 1, wherein, a conditional expression 1.0 < TTL / f < 1.10 is satisfied, where TTL is a distance along the optical axis from an object side surface of the first lens to the imaging surface of the image sensor, and f is a focal length of the optical imaging system.

9. The optical imaging system of claim 1, wherein, a conditional expression TTL / (2×IMG HT) <0.69 is satisfied, where TTL is a distance along the optical axis from an object side surface of the first lens to the imaging surface of the image sensor, and IMG HT is half of a diagonal length of the imaging surface of the image sensor.

10. The optical imaging system of claim 1, wherein, ​ 11. The optical imaging system of claim 1, wherein, satisfies a conditional expression 0.30 < R1 / f < 0.40, where R1 is a radius of curvature of an object side surface of the first lens, and f is a focal length of the optical imaging system.

12. The optical imaging system of claim 1, wherein, A refractive index of each of at least two lenses among the first lens to the seventh lens is 1.67 or more.

13. The optical imaging system of claim 1, wherein, A refractive index of each of either one or both of the second lens and the third lens is 1.67 or more.

14. The optical imaging system of claim 1, wherein, Each of an object side surface and an image side surface of each of the first lens to the seventh lens is aspherical.

Images