Optical imaging system

Abstract

An optical imaging system includes, in order from an object side of the optical imaging system toward an imaging surface of an image sensor along an optical axis of the optical imaging system, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, wherein a condition expression 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, and a condition expression TTL / (2xIMG HT) < 0.69 is satisfied, where TTL is a distance from an object side surface of the first lens to the imaging surface of the image sensor along the optical axis, and IMG HT is half of a diagonal length of the imaging surface of the image sensor.

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 to seventh lenses can be 1.67 or more.

[0019] The first lens can have a positive refractive power, either one or both of the second and third lenses can have a negative refractive power, and a refractive index of each of the second and third lenses 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, 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. The first lens has positive refractive power, and either or both of the second and third lenses have negative refractive power, satisfying the conditional expression n2+n3>3.15, where n2 is the refractive index of the second lens and n3 is the refractive index of the third lens, and satisfying the condition TTL / (2×IMG HT)<0.69, 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.

[0022] 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.

[0023] It can satisfy the conditional expressions v1-v2>30 and n2+n3+n4>4.85, where v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and n4 is the refractive index of the fourth lens.

[0024] Other features and aspects will become apparent from the following detailed description and accompanying drawings. Attached Figure Description

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

[0026] Figure 2 It is shown Figure 1 The diagram shows the aberration characteristics of the optical imaging system.

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

[0028] Figure 4 It is shown Figure 3 The diagram shows the aberration characteristics of the optical imaging system.

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

[0030] Figure 6 It is shown Figure 5 The diagram shows the aberration characteristics of the optical imaging system.

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

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

[0033] Figure 9 is a graph illustrating

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

[0035] In all the drawings and specific embodiments, the same reference numerals refer to the same elements. The drawings can not be drawn to scale, and the relative sizes, proportions, and depictions of elements in the drawings can be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0036] The following detailed description is provided to help the reader obtain a thorough understanding of the methods, devices, and / or systems described in this application. However, various changes, modifications, and equivalents in the methods, devices, and / or systems described in this application will be apparent after an understanding of the disclosure of this application. For example, the order of the operations described in this application is merely an example, and is not limited to the order set forth in this application, except for operations that must occur in a specific order, and can be changed as will be apparent after an understanding of the disclosure of this application. In addition, descriptions of features that are well known in the art can be omitted for the sake of clarity and brevity.

[0037] The features described in this application can be implemented in different forms and should not be construed as being limited to the examples described in this application. Rather, the examples described in this application are provided merely to illustrate some of the many possible ways of implementing the methods, devices, and / or systems described in this application, which will be apparent after an understanding of the disclosure of this application.

[0038] The terminology used in this application is for the purpose of describing various examples only and is not intended to limit the disclosure. Unless the context clearly indicates otherwise, the articles "a," "an," and "the" are intended to include both the singular and the plural. The expressions "including," "containing," and "having" are inclusive and do not exclude the presence of one or more other features, numbers, operations, members, 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 numerical values of 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 angle of field (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. Thus, 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 of the light ray incident to the surface of the lens with the optical axis is a small angle θ, and the approximations sinθ≈θ, tanθ≈θ, and cosθ≈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, the optical imaging system can include other elements in addition to the seven lenses.

[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 on 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 any 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]

[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 two or more of the following conditional expressions 1 through 11.

[0062] f / f2 + f / f3 < -0.4 (Condition Expression 1)

[0063] v1-v2 > 30 (Condition Expression 2)

[0064] 1.0 < TTL / f < 1.10 (Condition Expression 3)

[0065] n2+n3 > 3.15 (Condition Expression 4)

[0066] 0.15 < BFL / f < 0.25 (Condition Expression 5)

[0067] 0.005 < D1 / f < 0.04 (Condition Expression 6)

[0068] 0.30 < R1 / f < 0.40 (Condition Expression 7)

[0069] TTL / (2 x IMG HT) < 0.69 (Condition Expression 8)

[0070] Fno < 2.3 (Condition Expression 9)

[0071] n2+n3+n4 > 4.85 (Condition Expression 10)

[0072] 1.4 < |f23| / f1 < 2.8 (Condition Expression 11)

[0073] In the Condition 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 the 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 lens to the seventh lens in the example of the 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 face and the second face 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 face and the second face 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 face and the second face 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 face and the second face 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 face and the second face of the fourth lens can be convex.

[0085] Either one or both of the first face and the second face 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 illustrating a first example of an optical imaging system, and Figure 2 is a diagram illustrating Figure 1 aberration characteristics of the optical imaging system illustrated 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 illustrated 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]

[0111]

[0112] 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.

[0113] The Fno is a numerical 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.

[0114] 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.

[0115] 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.

[0116] The third lens 130 can have a positive refractive power, the first surface of the third lens 130 can be convex in a paraxial region of the first surface, and the second surface of the third lens 130 can be concave in a paraxial region of the second surface.

[0117] 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 a paraxial region of the first surface, and concave in an edge region of the first surface. The second surface of the third lens 130 can be concave in a paraxial region of the second surface, and convex in an edge region of the second surface.

[0118] 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.

[0119] The fifth lens 150 can have a positive refractive power, the first surface of the fifth lens 150 can be convex in a paraxial region of the first surface, and the second surface of the fifth lens 150 can be concave in a paraxial region of the second surface.

[0120] 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 a paraxial region of the first surface, and concave in an edge region of the first surface. The second surface of the fifth lens 150 can be concave in a paraxial region of the second surface, and convex in an edge region of the second surface.

[0121] The sixth lens 160 can have a positive refractive power, and the first and second surfaces of the sixth lens 160 can be convex.

[0122] 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 a paraxial region of the first surface, and concave in an edge region of the first surface. The second surface of the sixth lens 160 can be convex in a paraxial region of the second surface, and concave in an edge region of the second surface.

[0123] The seventh lens 170 can have a negative refractive power, the first surface of the seventh lens 170 can be concave in a paraxial region of the first surface, and the second surface of the seventh lens 170 can be concave in a paraxial region of the second surface.

[0124] At least one inflection point may be formed on either or both of the first and second surfaces of the seventh lens 170. For example, the first surface of the seventh lens 170 may be concave in the paraxial region of the first surface and convex in the edge region of the first surface. The second surface of the seventh lens 170 may be concave in the paraxial region of the second surface and convex in the edge region of the second surface.

[0125] The surfaces of the first lens 110 to the seventh lens 170 may 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 lens 110 to the seventh lens 170 may be aspherical.

[0126] Table 2

[0127]

[0128]

[0129] Figure 1 The first example of the optical imaging system shown, configured according to Tables 1 and 2 above, may have: Figure 2 The aberration characteristics shown are illustrated.

[0130] Figure 3 This is a diagram illustrating a second example of an optical imaging system, and Figure 4 It is shown Figure 3 The diagram shows the aberration characteristics of the optical imaging system.

[0131] The optical imaging system of the second example may 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 may also include an aperture (not shown), a filter 280 and an image sensor 290.

[0132] The following table 3 lists... Figure 3 The characteristics of the elements shown include the radius of curvature of the element's surface, 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.

[0133] Table 3

[0134]

[0135]

[0136] In the second example, the focal length f of the optical imaging system is 6.000 mm, Fno is 2.18, FOV is 72.96°, BFL is 0.908 mm, TTL is 6.202 mm, and IMG HT is 4.56 mm.

[0137] Definitions of Fno, FOV, BFL, TTL, and IMG HT are the same as in the first example.

[0138] In the second example, the first lens 210 can have a positive refractive power, the first face of the first lens 210 can be convex, and the second face of the first lens 210 can be concave.

[0139] The second lens 220 can have a positive refractive power, the first face of the second lens 220 can be convex, and the second face of the second lens 220 can be concave.

[0140] The third lens 230 can have a negative refractive power, the first face of the third lens 230 can be convex, and the second face of the third lens 230 can be concave.

[0141] The fourth lens 240 can have a positive refractive power, the first face of the fourth lens 240 can be convex in the paraxial region of the first face, and the second face of the fourth lens 240 can be concave in the paraxial region of the second face.

[0142] At least one inflection point can be formed on either one or both of the first and second faces of the fourth lens 240. For example, the first face of the fourth lens 240 can be convex in the paraxial region of the first face and concave in the edge region of the first face. The second face of the fourth lens 240 can be concave in the paraxial region of the second face and convex in the edge region of the second face.

[0143] The fifth lens 250 can have a positive refractive power, the first face of the fifth lens 250 can be convex in the paraxial region of the first face, and the second face of the fifth lens 250 can be concave in the paraxial region of the second face.

[0144] At least one inflection point can be formed on either one or both of the first and second faces of the fifth lens 250. For example, the first face of the fifth lens 250 can be convex in the paraxial region of the first face and concave in the edge region of the first face. The second face of the fifth lens 250 can be concave in the paraxial region of the second face and convex in the edge region of the second face.

[0145] The sixth lens 260 can have a positive refractive power, the first face of the sixth lens 260 can be convex in the paraxial region of the first face, and the second face of the sixth lens 260 can be convex in the paraxial region of the second face.

[0146] At least one inflection point may be formed on either or both of the first and second surfaces of the sixth lens 260. For example, the first surface of the sixth lens 260 may convex in the paraxial region of the first surface and concave in the edge region of the first surface. The second surface of the sixth lens 260 may convex in the paraxial region of the second surface and concave in the edge region of the second surface.

[0147] The seventh lens 270 may have negative refractive power, and the first surface of the seventh lens 270 may be concave in the paraxial region of the first surface, and the second surface of the seventh lens 270 may be concave in the paraxial region of the second surface.

[0148] At least one inflection point may be formed on either or both of the first and second surfaces of the seventh lens 270. For example, the first surface of the seventh lens 270 may be concave in the paraxial region of the first surface and convex in the edge region of the first surface. The second surface of the seventh lens 270 may be concave in the paraxial region of the second surface and convex in the edge region of the second surface.

[0149] The surfaces of the first lens 210 through the seventh lens 270 may have aspheric coefficients listed in Table 4 below. For example, each of the object-side surface and the image-side surface of each of the first lens 210 through the seventh lens 270 may be aspherical.

[0150] Table 4

[0151] S1 S2 S3 S4 S5 S6 S7 K -1.048 -21.819 16.835 11.583 -11.465 5.970 -79.619 A 0.008 -0.106 -0.153 -0.038 -0.002 -0.025 -0.026 B 0.027 0.119 0.268 0.185 0.004 0.129 -0.052 C -0.069 0.101 -0.170 -0.375 -0.163 -0.706 0.227 D 0.114 -0.420 -0.109 0.431 0.390 1.852 -0.623 E -0.116 0.537 0.295 -0.310 -0.415 -2.706 0.949 F 0.072 -0.371 -0.243 0.144 0.240 2.377 -0.856 G -0.026 0.145 0.100 -0.042 -0.070 -1.238 0.457 H 0.005 -0.030 -0.020 0.007 0.006 0.349 -0.132 J 0.000 0.003 0.002 -0.001 0.001 -0.041 0.016 S8 S9 S10 S11 S12 S13 S14 K -99.000 -22.463 -24.850 -55.438 43.550 -8.774 -99.000 A -0.057 -0.036 -0.039 0.027 0.039 -0.083 -0.050 B -0.002 -0.006 -0.018 -0.065 -0.041 0.034 0.015 C 0.094 0.037 0.056 0.043 0.018 -0.008 -0.003 D -0.289 -0.038 -0.051 -0.023 -0.006 0.001 0.000 E 0.394 0.016 0.024 0.009 0.002 0.000 0.000 F -0.302 -0.003 -0.006 -0.002 0.000 0.000 0.000 G 0.134 0.000 0.001 0.000 0.000 0.000 0.000 H -0.032 0.000 0.000 0.000 0.000 0.000 0.000 J 0.003 0.000 0.000 0.000 0.000 0.000 0.000

[0152] Figure 3 The second example of the optical imaging system shown, configured according to Tables 3 and 4 above, may have... Figure 4 The aberration characteristics shown are illustrated.

[0153] Figure 5 This is a diagram illustrating a third example of an optical imaging system, and Figure 6 It is shown Figure 5 The diagram shows the aberration characteristics of the optical imaging system.

[0154] The optical imaging system of the third example may 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 may also include an aperture, a filter 380 and an image sensor 390.

[0155] The following table 5 lists... Figure 5 The characteristics of the elements shown include the radius of curvature of the element's surface, 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.

[0156] Table 5

[0157]

[0158] 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.

[0159] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0160] In the third example, the first lens 310 can have a positive refractive power, the first surface of the first lens 310 can be convex, and the second surface of the first lens 310 can be concave.

[0161] The second lens 320 can have a negative refractive power, the first surface of the second lens 320 can be convex, and the second surface of the second lens 320 can be concave.

[0162] The third lens 330 can have a negative refractive power, the first surface of the third lens 330 can be convex in the paraxial region of the first surface, and the second surface of the third lens 330 can be concave in the paraxial region of the second surface.

[0163] At least one inflection point can be formed on either one 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 the paraxial region of the first surface and concave in the edge region of the first surface. The second surface of the third lens 330 can be concave in the paraxial region of the second surface and convex in the edge region of the second surface.

[0164] The fourth lens 340 can have a positive refractive power, the first surface of the fourth lens 340 can be flat in the paraxial region of the first surface, and the second surface of the fourth lens 340 can be convex in the paraxial region of the second surface.

[0165] At least one inflection point can be formed on either one 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 the paraxial region of the first surface and convex in the edge region of the first surface.

[0166] The fifth lens 350 can have a positive refractive power, and the first and second surfaces of the fifth lens 350 can be convex.

[0167] The sixth lens 360 can have a positive refractive power, the first surface of the sixth lens 360 can be concave, and the second surface of the sixth lens 360 can be convex.

[0168] The seventh lens 370 may have negative refractive power, and the first surface of the seventh lens 370 may be concave in the paraxial region of the first surface, and the second surface of the seventh lens 370 may be concave in the paraxial region of the second surface.

[0169] At least one inflection point may 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 may be concave in the paraxial region of the first surface and convex in the edge region of the first surface. The second surface of the seventh lens 370 may be concave in the paraxial region of the second surface and convex in the edge region of the second surface.

[0170] The surfaces of the first lens 310 to the seventh lens 370 may 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 lens 310 to the seventh lens 370 may be aspherical.

[0171] Table 6

[0172] S1 S2 S3 S4 S5 S6 S7 K -0.841 26.507 15.248 6.857 0.000 0.000 -95.502 A 0.019 -0.011 0.017 0.019 -0.123 -0.131 -0.064 B -0.008 0.055 0.078 0.022 0.087 0.141 0.013 C 0.039 -0.131 -0.180 0.064 -0.056 -0.174 0.014 D -0.072 0.195 0.288 -0.227 0.170 0.362 0.006 E 0.077 -0.185 -0.292 0.378 -0.293 -0.467 -0.024 F -0.047 0.107 0.184 -0.332 0.266 0.353 0.021 G 0.015 -0.034 -0.063 0.156 -0.124 -0.146 -0.008 H -0.002 0.004 0.009 -0.030 0.023 0.025 0.001 J 0.000 0.000 0.000 0.000 0.000 0.000 0.000 S8 S9 S10 S11 S12 S13 S14 K -1.463 83.726 19.055 6.205 3.301 35.076 -0.120 A -0.054 -0.054 -0.081 -0.039 0.035 -0.109 -0.149 B 0.001 0.043 0.164 0.115 -0.009 0.031 0.064 C 0.020 -0.072 -0.218 -0.168 -0.027 -0.005 -0.026 D -0.037 0.050 0.154 0.112 0.022 0.001 0.008 E 0.042 -0.018 -0.064 -0.043 -0.008 0.000 -0.002 F -0.026 0.002 0.016 0.011 0.001 0.000 0.000 G 0.009 0.000 -0.002 -0.002 0.000 0.000 0.000 H -0.001 0.000 0.000 0.000 0.000 0.000 0.000 J 0.000 0.000 0.000 0.000 0.000 0.000 0.000

[0173] Figure 5 The third example of the optical imaging system shown, configured according to Tables 5 and 6 above, may have... Figure 6 The aberration characteristics shown are illustrated.

[0174] Figure 7 This is a diagram illustrating a fourth example of an optical imaging system, and Figure 8 It is shown Figure 7 The diagram shows the aberration characteristics of the optical imaging system.

[0175] The optical imaging system of the fourth example may 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 may also include an aperture, a filter 480 and an image sensor 490.

[0176] The following table 7 lists... Figure 7 The characteristics of the elements shown include the radius of curvature of the element's surface, 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.

[0177] Table 7

[0178]

[0179] In the fourth example, the focal length f of the optical imaging system is 6.000 mm, Fno is 2.20, FOV is 74.55°, BFL is 1.196 mm, TTL is 6.200 mm, and IMG HT is 4.56 mm.

[0180] Definitions of Fno, FOV, BFL, TTL, and IMG HT are the same as in the first example.

[0181] In the fourth example, the first lens 410 can have a positive refractive power, a first surface of the first lens 410 can be convex, and a second surface of the first lens 410 can be concave.

[0182] The second lens 420 can have a negative refractive power, a first surface of the second lens 420 can be convex, and a second surface of the second lens 420 can be concave.

[0183] The third lens 430 can have a negative refractive power, a first surface of the third lens 430 can be convex in a paraxial region of the first surface, and a second surface of the third lens 430 can be concave.

[0184] At least one inflection point can be formed on either one 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 an edge region of the first surface.

[0185] The fourth lens 440 can have a positive refractive power, and the first and second surfaces of the fourth lens 440 can be convex.

[0186] The fifth lens 450 can have a positive refractive power, and the first and second surfaces of the fifth lens 450 can be convex.

[0187] The sixth lens 460 can have a negative refractive power, a first surface of the sixth lens 460 can be concave, and a second surface of the sixth lens 460 can be convex.

[0188] The seventh lens 470 can have a negative refractive power, a first surface of the seventh lens 470 can be concave in a paraxial region of the first surface, and a second surface of the seventh lens 470 can be concave in a paraxial region of the second surface.

[0189] At least one inflection point can be formed on either one 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 an edge 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 an edge region of the second surface.

[0190] 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 side surface and the image side surface of each of the first through seventh lenses 410-470 can be aspheric.

[0191] Table 8

[0192]

[0193]

[0194] Figure 7 A fourth example of the optical imaging system shown in FIG. 5 configured according to the above Table 7 and Table 8 can have Figure 8 aberration characteristics shown in FIG. 6.

[0195] Figure 9 is a graph showing aberration characteristics of the optical imaging system shown in FIG. 5. Figure 10 is a graph showing Figure 9 aberration characteristics of the optical imaging system shown in FIG. 5.

[0196] The optical imaging system of the fifth example can include a first lens 510, a second lens 520, a third lens 530, a fourth lens 540, a fifth lens 550, a sixth lens 560, and a seventh lens 570, and can further include a stop, a filter 580, and an image sensor 590.

[0197] In the following Table 9, characteristics of the elements shown in FIG. 5 are listed, including radii of curvature of surfaces of the elements, thicknesses of the elements, distances between the elements, refractive indices of the elements, Abbe numbers of the elements, and focal lengths of the elements. Figure 9

[0198] Table 9

[0199]

[0200]

[0201] 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.

[0202] The definitions of the Fno, the FOV, the BFL, the TTL, and the IMG HT are the same as in the first example.

[0203] In the fifth example, the first lens 510 can have a positive refractive power, the first face of the first lens 510 can be convex, and the second face of the first lens 510 can be concave.

[0204] The second lens 520 can have a negative refractive power, the first face of the second lens 520 can be convex, and the second face of the second lens 520 can be concave.

[0205] ​The third lens 530 can have a positive refractive power, a first surface of the third lens 530 can be convex, and a second surface of the third lens 530 can be concave.

[0206] The fourth lens 540 can have a negative refractive power, a first surface of the fourth lens 540 can be convex in a paraxial region of the first surface, and a second surface of the fourth lens 540 can be concave in a paraxial region of the second surface.

[0207] 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 a paraxial region of the first surface and concave in an edge region of the first surface. The second surface of the fourth lens 540 can be concave in a paraxial region of the second surface and convex in an edge region of the second surface.

[0208] The fifth lens 550 can have a negative refractive power, a first surface of the fifth lens 550 can be concave, and a second surface of the fifth lens 550 can be concave.

[0209] The sixth lens 560 can have a positive refractive power, a first surface of the sixth lens 560 can be convex in a paraxial region of the first surface, and a second surface of the sixth lens 560 can be concave in a paraxial region of the second surface.

[0210] 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 a paraxial region of the first surface and concave in an edge region of the first surface. The second surface of the sixth lens 560 can be concave in a paraxial region of the second surface and convex in an edge region of the second surface.

[0211] The seventh lens 570 can have a negative refractive power, a first surface of the seventh lens 570 can be convex in a paraxial region of the first surface, and a second surface of the seventh lens 570 can be concave in a paraxial region of the second surface.

[0212] 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 a paraxial region of the second surface and convex in an edge region of the second surface.

[0213] 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.

[0214] Table 10

[0215]

[0216]

[0217] Figure 9 A fifth example of the optical imaging system shown in FIG. 1 1 can have the configurations according to the above Table 9 and Table 10 in the first example to the fifth example. Figure 10 aberration characteristics shown in FIG. 1 1.

[0218] Table 1 1 below lists the values of the conditional expressions 1 to 1 1 in the first example to the fifth example.

[0219] Table 1 1

[0220]

[0221] 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.

[0222] While the present disclosure includes specific examples, it will be apparent to one of ordinary skill in the art, after having regard to the disclosure contained herein, that various changes in form and detail can be made without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to 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 components in the described systems, architectures, devices, or circuits are combined in a different manner, and / or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure should be determined by the following claims and their equivalents, rather than by the described examples, and all variations within the scope of the claims and their equivalents are intended to be embraced.

Claims

1. An optical imaging system, comprising: first, second, third, fourth, fifth, sixth, and seventh lenses disposed in a sequence in a numerical order from an object side of the optical imaging system toward an imaging surface of an image sensor along an optical axis of the optical imaging system, wherein a number of lenses having refractive power in the optical imaging system is seven, wherein the first lens has positive refractive power, a convex object side surface, and a concave image side surface, the second lens has a convex object side surface and a concave image side surface, the third lens has a convex object side surface and a concave image side surface, and the seventh lens has negative refractive power and a concave image side surface, wherein a conditional expression -0.89 ≤ f / f2 + f / f3 ≤ -0.44 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 0.6707 ≤ TTL / (2×IMG HT) < 0.69 is satisfied, where TTL is a distance from an object side surface of the first lens to the imaging surface of the image sensor along the optical axis, and IMG HT is half of a diagonal length of the imaging surface of the image sensor, a conditional expression 1.0 < TTL / f < 1.10 is satisfied, and wherein refractive power distributions of the second, third, fourth, fifth, and sixth lenses are one of: negative, positive, negative, negative, positive; negative, negative, positive, positive, negative; negative, negative, positive, positive, positive; positive, negative, positive, positive, positive; and negative, positive, positive, positive, positive.

2. The optical imaging system of claim 1, wherein, 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.

3. The optical imaging system of claim 2, wherein, a conditional expression n2 + n3 + n4 > 4.85 is satisfied, where n4 is a refractive index of the fourth lens.

4. The optical imaging system of claim 2, wherein, a conditional expression v1 - v2 > 30 is satisfied, where v1 is an Abbe number of the first lens, and v2 is an Abbe number of the second 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 from an image side surface of the seventh lens to the imaging surface of the image sensor along the optical axis.

6. The optical imaging system of claim 1, wherein, a conditional expression 0.005 < D1 / f < 0.04 is satisfied, where 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.

7. The optical imaging system of claim 1, wherein, a conditional expression 0.30 < R1 / f < 0.40 is satisfied, where R1 is a radius of curvature of an object side surface of the first lens.

8. The optical imaging system of claim 1, wherein, 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 and third lenses.

9. 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.

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

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

12. An optical imaging system comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from an object side of the optical imaging system toward an imaging surface of an image sensor along an optical axis of the optical imaging system in a numerical ascending order, wherein the number of lenses having refractive power in the optical imaging system is seven, wherein the first lens has positive refractive power, a convex object side surface, and a concave image side surface, the second lens has a convex object side surface and a concave image side surface, the third lens has a convex object side surface and a concave image side surface, and the seventh lens has negative refractive power and a concave image side surface, a condition expression 3.37 ≥ n2+n3 > 3.15 is satisfied, where n2 is the refractive index of the second lens and n3 is the refractive index of the third lens, a condition expression 0.6707 ≤ TTL / (2xIMG HT) < 0.69 is satisfied, where TTL is a distance from an object side surface of the first lens to the imaging surface of the image sensor along the optical axis and IMG HT is half of a diagonal length of the imaging surface of the image sensor, a condition expression 1.0 < TTL / f < 1.10 is satisfied, where f is a focal length of the optical imaging system, a condition expression -0.89 ≤ f / f2+f / f3 ≤ -0.44 is satisfied, where f2 is a focal length of the second lens and f3 is a focal length of the third lens, and wherein the refractive power distribution of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens is one of: negative, positive, negative, negative, positive; negative, negative, positive, positive, negative; negative, negative, positive, positive, positive; positive, negative, positive, positive, positive; and negative, positive, positive, positive, positive.

13. The optical imaging system of claim 12, wherein, a condition expression v1-v2 > 30 and n2+n3+n4 > 4.85 is satisfied, where v1 is the Abbe number of the first lens, v2 is the Abbe number of the second lens, and n4 is the refractive index of the fourth lens.

Images