Optical imaging system

Abstract

The present invention provides an optical imaging system, comprising: a first lens having a convex object-side surface; a second lens having a convex object-side surface; a third lens having a convex object-side surface; a fourth lens having a negative refractive power and a concave image-side surface; a fifth lens having a concave image-side surface; and a sixth lens having a convex object-side surface, wherein the first lens to the sixth lens are arranged sequentially from the object side.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0154877 filed on November 20, 2017, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety for all purposes by reference. Technical Field

[0002] The present application relates to an optical imaging system comprising six lenses. Background Art

[0003] A compact camera module may be installed in a mobile communication terminal. For example, a compact camera module may be installed in a slim device such as a mobile phone. Such compact camera modules include an optical imaging system having a small number of lenses so that they may also be slim. For example, the optical imaging system of a compact camera module may include four or fewer lenses.

[0004] However, such an optical imaging system may have a high f-number (F No.), so that the optical imaging system may be difficult to use in a small camera module with high performance.

[0005] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with respect to the present disclosure. Summary of the invention

[0006] This summary is provided to introduce selected concepts in a simplified form that are further described in the detailed description below. This summary is neither intended to identify key features or essential features of the claimed subject matter nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] In a general aspect, an optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in order from an object side. The third lens and the sixth lens have positive refractive power, and the f-number (F No.) of the optical imaging system is 1.7 or less.

[0008] The first lens may have positive refractive power.

[0009] The second lens may have negative refractive power.

[0010] The fourth lens may have negative refractive power.

[0011] TTL / (IMG HT) may be less than 1.5, wherein TTL is the distance on the optical axis from the object surface of the first lens to the imaging plane of the optical imaging system, and IMG HT is half of the diagonal length of the imaging plane.

[0012] In another general aspect, an optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in order from the object side. The object side surface and the image side surface of the fourth lens are concave. The image side surface of the sixth lens is concave, and the f-number (F No.) of the optical imaging system is 1.7 or less.

[0013] The object-side surface of the first lens may be convex.

[0014] The object-side surface of the second lens may be convex.

[0015] An object-side surface of the third lens may be convex.

[0016] An image-side surface of the fifth lens may be concave.

[0017] An object-side surface of the sixth lens may be convex.

[0018] The full field of view (FOV) of the optical imaging system may be 75° or greater.

[0019] R2 / R1 may be greater than 20, wherein R1 is a radius of curvature of an object-side surface of the first lens, and R2 is a radius of curvature of an image-side surface of the first lens.

[0020] R8 / R10 may be greater than 0 and less than 2.0, wherein R8 is a radius of curvature of an image-side surface of the fourth lens, and R10 is a radius of curvature of an image-side surface of the fifth lens.

[0021] R11 / R12 may be greater than 0 and less than 1.2, wherein R11 is a curvature radius of an object-side surface of the sixth lens, and R12 is a curvature radius of an image-side surface of the sixth lens.

[0022] D45 / D56 may be greater than 5.0 and less than 10, wherein D45 is the distance on the optical axis from the image surface of the fourth lens to the object surface of the fifth lens, and D56 is the distance on the optical axis from the image surface of the fifth lens to the object surface of the sixth lens.

[0023] In another general aspect, an optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens sequentially arranged from an object side toward an imaging plane of the optical imaging system. The first lens, the third lens, and the sixth lens each have a refractive index less than the refractive index of the second lens, the fourth lens, and the fifth lens, and an f-number (F No.) of the optical imaging system is 1.7 or less.

[0024] The first lens, the third lens, and the sixth lens may each have a refractive index of 1.56 or less, and the second lens, the fourth lens, and the fifth lens may each have a refractive index of 1.6 or more.

[0025] The first lens and the third lens may each have an Abbe number greater than Abbe numbers of the second lens, the fourth lens, the fifth lens, and the sixth lens.

[0026] The first lens and the third lens may each have an Abbe number of 55 or more, and the second lens may have an Abbe number of 22 or less.

[0027] Other features and aspects will be apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a diagram illustrating a first example of an optical imaging system.

[0029] Figure 2 Shows the representation Figure 1 Graphs of the aberration characteristics of the optical imaging system shown in .

[0030] Figure 3 is a diagram illustrating a second example of the optical imaging system.

[0031] Figure 4 Shows the representation Figure 3 Graphs of the aberration characteristics of the optical imaging system shown in .

[0032] Figure 5 is a diagram illustrating a third example of the optical imaging system.

[0033] Figure 6 Shows the representation Figure 5 Graphs of the aberration characteristics of the optical imaging system shown in .

[0034] In all drawings and detailed description, the same reference numerals refer to the same elements. The drawings may not be drawn to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0035] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0036] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0037] In the drawings, for the convenience of explanation, the thickness, size and shape of the lens are slightly exaggerated. Specifically, the shapes of the spherical surface or the aspherical surface shown in the drawings are shown by way of example. That is, the shapes of the spherical surface or the aspherical surface are not limited to those shown in the drawings.

[0038] Note that the term "may" used herein with respect to examples or embodiments (e.g., regarding what an example or embodiment may include or implement) means that there is at least one example or embodiment that includes or implements such features, but all examples and embodiments are not limited thereto.

[0039] In addition, in the present application, the first lens refers to the lens closest to the object (or subject), and the sixth lens refers to the lens closest to the imaging plane (or image sensor). In addition, the radius of curvature and thickness of the lens, the distance from the object surface of the first lens to the imaging plane (TTL), half the diagonal length of the imaging plane (IMG HT), and the focal length of the lens are all expressed in millimeters (mm). In addition, the thickness of the lens, the spacing between the lenses, and TTL are distances measured on the optical axis of the lens. In addition, in the description of the shape of the lens, the meaning of one surface of the lens being convex is that the optical axis portion of the corresponding surface is convex, and the meaning of one surface of the lens being concave is that the optical axis portion of the corresponding surface is concave. Therefore, although one surface of the lens is described as convex, the edge portion of the one surface of the lens may be concave. Similarly, although one surface of the lens is described as concave, the edge portion of the one surface of the lens may be convex.

[0040] An aspect of the present disclosure may provide an optical imaging system that can be used in a small camera module with high performance.

[0041] The optical imaging system may include six lenses arranged sequentially from the object side toward the imaging surface. For example, the optical imaging system may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially. The first lens to the sixth lens may be arranged with a predetermined spacing therebetween. For example, a predetermined spacing may be formed between the image side surface of the first lens and the object side surface of the second lens.

[0042] The first lens may have a refractive power. For example, the first lens may have a positive refractive power.

[0043] One surface of the first lens may be convex. For example, the object-side surface of the first lens may be convex. The first lens may have an aspherical surface. For example, both surfaces of the first lens may be aspherical. The first lens may be formed using a material having high light transmittance and excellent processability. For example, the first lens may be formed using plastic. However, the material of the first lens is not limited to plastic. For example, the first lens may be formed using glass.

[0044] The first lens may have a predetermined refractive index. For example, the refractive index of the first lens may be less than 1.6. The first lens may have a predetermined Abbe number. For example, the Abbe number of the first lens may be 50 or greater.

[0045] The second lens may have refractive power. For example, the second lens may have negative refractive power.

[0046] One surface of the second lens may be convex. For example, the object-side surface of the second lens may be convex. The second lens may have an aspherical surface. For example, both surfaces of the second lens may be aspherical. The second lens may be formed using a material having high light transmittance and excellent processability. For example, the second lens may be formed using plastic. However, the material of the second lens is not limited to plastic. For example, the second lens may also be formed using glass.

[0047] The second lens may have a refractive index greater than that of the first lens. For example, the refractive index of the second lens may be 1.6 or greater. The second lens may have a predetermined Abbe number. For example, the Abbe number of the second lens may be less than 24.

[0048] The third lens may have refractive power. For example, the third lens may have positive refractive power.

[0049] One surface of the third lens may be convex. For example, the object-side surface of the third lens may be convex. The third lens may have an aspherical surface. For example, both surfaces of the third lens may be aspherical. The third lens may be formed using a material having high light transmittance and excellent processability. For example, the third lens may be formed using plastic. However, the material of the third lens is not limited to plastic. For example, the third lens may be formed using glass.

[0050] The third lens may have a refractive index substantially similar to that of the first lens. For example, the refractive index of the third lens may be less than 1.6. The third lens may have an Abbe number similar to that of the first lens. For example, the Abbe number of the third lens may be 50 or greater.

[0051] The fourth lens may have refractive power. For example, the fourth lens may have negative refractive power.

[0052] One surface of the fourth lens may be concave. For example, the object-side surface of the fourth lens may be concave. The fourth lens may have an aspherical surface. For example, both surfaces of the fourth lens may be aspherical. The fourth lens may be formed using a material having high light transmittance and excellent processability. For example, the fourth lens may be formed using plastic. However, the material of the fourth lens is not limited to plastic. For example, the fourth lens may be formed using glass.

[0053] The fourth lens may have a refractive index greater than that of the first lens. For example, the refractive index of the fourth lens may be 1.6 or greater. The fourth lens may have an Abbe number less than that of the first lens. For example, the Abbe number of the fourth lens may be less than 30.

[0054] The fifth lens may have refractive power. For example, the fifth lens may have negative refractive power.

[0055] One surface of the fifth lens may be concave. For example, the image-side surface of the fifth lens may be concave. The fifth lens may have an aspherical surface. For example, both surfaces of the fifth lens may be aspherical. The fifth lens may have an inflection point. For example, one or more inflection points may be formed on the object-side surface and / or the image-side surface of the fifth lens.

[0056] The fifth lens may be formed using a material having high light transmittance and excellent processability. For example, the fifth lens may be formed using plastic. However, the material of the fifth lens is not limited to plastic. For example, the fifth lens may be formed using glass.

[0057] The fifth lens may have a refractive index greater than that of the first lens. For example, the refractive index of the fifth lens may be 1.6 or greater. The fifth lens may have an Abbe number less than that of the first lens. For example, the Abbe number of the fifth lens may be 30 or less.

[0058] The sixth lens may have refractive power. For example, the sixth lens may have positive refractive power.

[0059] One surface of the sixth lens may be concave. For example, the image-side surface of the sixth lens may be concave. The sixth lens may have an inflection point. For example, one or more inflection points may be formed on both surfaces of the sixth lens. The sixth lens may have an aspherical surface. For example, both surfaces of the sixth lens may be aspherical.

[0060] The sixth lens may be formed using a material having high light transmittance and excellent processability. For example, the sixth lens may be formed using plastic. However, the material of the sixth lens is not limited to plastic. For example, the sixth lens may be formed using glass.

[0061] The sixth lens may have a refractive index substantially similar to that of the first lens. For example, the refractive index of the sixth lens may be less than 1.6. The sixth lens may have an Abbe number greater than that of the fifth lens. For example, the Abbe number of the sixth lens may be 50 or greater.

[0062] In addition, the f-number (F No.) of the optical imaging system may be 1.7 or less. The full field of view (FOV) of the optical imaging system may be 75° or greater.

[0063] As described above, the first lens to the sixth lens may have an aspherical shape. For example, at least one surface of all lenses in the first lens to the sixth lens may be aspherical. Here, the aspherical surface of each lens may be represented by the following formula 1:

[0064]

[0065] In Formula 1, c is the inverse of the radius of curvature of the lens, k is the cone constant, r is the distance from a point on the aspheric surface of the lens to the optical axis in a direction perpendicular to the optical axis, A to H are aspheric coefficients, and Z (or SAG) is the distance between a point on the aspheric surface of the lens at a distance r from the optical axis and a tangent plane intersecting the vertex of the aspheric surface of the lens.

[0066] The optical imaging system may further include an aperture stop, which may be disposed between the second lens and the third lens.

[0067] The optical imaging system may further include an optical filter. The optical filter may block incident light of a portion of wavelengths incident through the first lens to the sixth lens. For example, the optical filter may block incident light of infrared wavelengths.

[0068] The optical imaging system may further include an image sensor. The image sensor may provide an imaging surface, and light refracted by the lens may be imaged on the imaging surface. For example, the surface of the image sensor may form the imaging surface. The image sensor may be configured to achieve a high level of resolution.

[0069] The optical imaging system may satisfy the following conditional expressions 2-6:

[0070] TTL / (IMG HT)<1.5 (2)

[0071] 20 <R2 / R1 (3)

[0072] 0 <R8 / R10<2.0 (4)

[0073] 0 <R11 / R12<1.2 (5)

[0074] 5.0 <D45 / D56<10 (6)

[0075] In the above Conditional Expression 2 to Conditional Expression 6, TTL is the distance from the object-side surface of the first lens to the imaging plane, IMG HT is half the diagonal length of the imaging plane, R1 is the curvature radius of the object-side surface of the first lens, R2 is the curvature radius of the image-side surface of the first lens, R8 is the curvature radius of the image-side surface of the fourth lens, R10 is the curvature radius of the image-side surface of the fifth lens, R11 is the curvature radius of the object-side surface of the sixth lens, R12 is the curvature radius of the image-side surface of the sixth lens, D45 is the distance from the image-side surface of the fourth lens to the object-side surface of the fifth lens, and D56 is the distance from the image-side surface of the fifth lens to the object-side surface of the sixth lens.

[0076] Next, optical imaging systems according to several examples will be described.

[0077] Will refer to Figure 1 A first example of an optical imaging system is described.

[0078] The first example of the optical imaging system 100 may include a plurality of lenses having refractive power. For example, the optical imaging system 100 may include a first lens 110 , a second lens 120 , a third lens 130 , a fourth lens 140 , a fifth lens 150 , and a sixth lens 160 .

[0079] The first lens 110 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The second lens 120 may have negative refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The third lens 130 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The fourth lens 140 may have negative refractive power, and its object-side surface may be concave, and its image-side surface may be concave. The fifth lens 150 may have negative refractive power, and its object-side surface may be concave, and its image-side surface may be concave. In addition, an inflection point may be formed on the object-side surface and the image-side surface of the fifth lens 150. The sixth lens 160 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. In addition, an inflection point may be formed on both surfaces of the sixth lens 160. For example, the object-side surface of the sixth lens may be convex in the paraxial region and may be concave in the region surrounding the paraxial region, and the image-side surface thereof may be concave in the paraxial region and may be convex in the region surrounding the paraxial region.

[0080] The first lens 110, the third lens 130, and the sixth lens 160 may have relatively low refractive indices. For example, the refractive indexes of the first lens 110, the third lens 130, and the sixth lens 160 may be 1.56 or less. The second lens 120, the fourth lens 140, and the fifth lens 150 may have relatively high refractive indices. For example, the refractive indexes of the second lens 120, the fourth lens 140, and the fifth lens 150 may be 1.6 or greater. The second lens 120 may have the highest refractive index in the optical imaging system 100. For example, the refractive index of the second lens 120 may be 1.66 or greater. The sixth lens 160 may have the lowest refractive index in the optical imaging system 100. For example, the refractive index of the sixth lens 160 may be 1.54 or less.

[0081] The first lens 110 and the third lens 130 may have the largest Abbe number in the optical imaging system 100. For example, the Abbe number of the first lens 110 and the third lens 130 may be 55 or more. The second lens 120 may have the smallest Abbe number in the optical imaging system 100. For example, the Abbe number of the second lens 120 may be 22 or less.

[0082] The optical imaging system 100 may include a stop ST. For example, the stop ST may be disposed between the second lens 120 and the third lens 130. The stop ST disposed as described above may control the amount of light incident on the imaging surface 180.

[0083] The optical imaging system 100 may include an optical filter 170. For example, the optical filter 170 may be disposed between the sixth lens 160 and the imaging surface 180. The optical filter 170 disposed as described above may block infrared light incident on the imaging surface 180.

[0084] The optical imaging system 100 may include an image sensor. The image sensor may provide an imaging surface 180, and the light refracted by the lens is imaged on the imaging surface 180. The image sensor may convert the optical signal imaged on the imaging surface 180 into an electrical signal.

[0085] The optical imaging system 100 configured as described above may have a low f-number (F No.). For example, the F No. of the optical imaging system in the first example may be 1.680.

[0086] The optical imaging system in the first example may have Figure 2 Table 1 shows the characteristics of the lens of the optical imaging system in the first example, and Table 2 shows the aspherical surface characteristics of the optical imaging system in the first example.

[0087] Table 1

[0088]

[0089] Table 2

[0090] First example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of curvature 1.503 31.216 6.214 2.379 6.814 21.082 -48.326 22.417 -40.411 20.146 1.427 1.287 k -0.418 0.996 0.964 -1.000 -0.995 1.000 0.453 -0.291 41.061 -49.945 -1.996 -0.830 A -0.003 0.004 -0.012 0.013 -0.010 -0.032 -0.050 0.044 0.387 0.070 -0.525 -0.408 B 0.045 -0.058 -0.017 -0.045 -0.087 0.398 -0.050 -0.485 -0.947 -0.070 0.487 0.282 C -0.090 0.095 0.033 0.062 -0.120 -3.023 0.022 0.834 1.100 -0.078 -0.347 -0.167 D 0.093 -0.065 0.050 0.062 0.293 10.280 -0.038 -0.761 -0.85 0.125 0.17 0.07 E -0.057 -0.042 -0.032 -0.031 -0.271 -21.285 -0.050 0.289 0.379 -0.083 -0.053 -0.019 F 0.008 0.094 -0.050 -0.062 0.051 26.147 -0.036 0.042 -0.073 0.031 0.010 0.003 G 0.009 -0.066 0.042 -0.062 0.033 -17.499 0.050 -0.060 -0.001 -0.006 -0.001 0.000 H -0.006 0.017 -0.005 0.145 0.105 4.957 0.001 0.012 0.001 0.001 0.000 0.000

[0091] Will refer to Figure 3 A second example of an optical imaging system is described.

[0092] The optical imaging system 200 in the second example may include a plurality of lenses having refractive power. For example, the optical imaging system 200 may include a first lens 210 , a second lens 220 , a third lens 230 , a fourth lens 240 , a fifth lens 250 , and a sixth lens 260 .

[0093] The first lens 210 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The second lens 220 may have negative refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The third lens 230 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be convex. The fourth lens 240 may have negative refractive power, and its object-side surface may be concave, and its image-side surface may be concave. The fifth lens 250 may have negative refractive power, and its object-side surface may be convex, and its image-side surface may be concave. In addition, an inflection point may be formed on the object-side surface and the image-side surface of the fifth lens 250. The sixth lens 260 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. In addition, an inflection point may be formed on both surfaces of the sixth lens 260. For example, the object-side surface of the sixth lens may be convex in the paraxial region and may be concave in the region surrounding the paraxial region, and the image-side surface thereof may be concave in the paraxial region and may be convex in the region surrounding the paraxial region.

[0094] The first lens 210, the third lens 230, and the sixth lens 260 may have relatively low refractive indices. For example, the refractive indexes of the first lens 210, the third lens 230, and the sixth lens 260 may be 1.56 or less. The second lens 220, the fourth lens 240, and the fifth lens 250 may have relatively high refractive indices. For example, the refractive indexes of the second lens 220, the fourth lens 240, and the fifth lens 250 may be 1.6 or greater. The second lens 220 may have the highest refractive index in the optical imaging system 200. For example, the refractive index of the second lens 220 may be 1.66 or greater. The sixth lens 260 may have the lowest refractive index in the optical imaging system 200. For example, the refractive index of the sixth lens 260 may be 1.54 or less.

[0095] The first lens 210 and the third lens 230 may have the largest Abbe number in the optical imaging system 200. For example, the Abbe number of the first lens 210 and the third lens 230 may be 55 or more. The second lens 220 may have the smallest Abbe number in the optical imaging system 200. For example, the Abbe number of the second lens 220 may be 22 or less.

[0096] The optical imaging system 200 may include a stop ST. For example, the stop ST may be disposed between the second lens 220 and the third lens 230. The stop ST disposed as described above may control the amount of light incident on the imaging surface 280.

[0097] The optical imaging system 200 may include an optical filter 270. For example, the optical filter 270 may be disposed between the sixth lens 260 and the imaging surface 280. The optical filter 270 disposed as described above may block infrared light incident on the imaging surface 280.

[0098] The optical imaging system 200 may include an image sensor. The image sensor may provide an imaging surface 280, and the light refracted by the lens is imaged on the imaging surface 280. The image sensor may convert the optical signal imaged on the imaging surface 280 into an electrical signal.

[0099] The optical imaging system 200 configured as described above may have a low F No. For example, the F No. of the optical imaging system according to the present exemplary embodiment may be 1.689.

[0100] The optical imaging system in the second example may have Figure 4 Table 3 shows the characteristics of the lens of the optical imaging system in the second example, and Table 4 shows the aspherical surface characteristics of the optical imaging system in the second example.

[0101] Table 3

[0102]

[0103] Table 4

[0104] Second example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of curvature 1.523 57.595 5.700 2.392 19.599 -15.215 -20.767 14.466 352.603 60.254 1.449 1.251 k -0.455 0.762 0.721 -0.994 -0.995 1.000 0.453 -0.291 42.178 -49.952 -2.056 -0.828 A -0.002 -0.012 -0.037 -0.005 -0.020 -0.025 -0.044 0.059 0.406 0.112 -0.464 -0.406 B 0.046 -0.013 0.041 -0.009 -0.155 0.339 0.005 -0.530 -0.977 -0.100 0.386 0.278 C -0.093 0.075 0.044 0.062 0.232 -2.561 -0.012 0.937 1.100 -0.063 -0.259 -0.168 D 0.085 -0.095 -0.031 0.050 -0.310 8.395 -0.050 -0.905 -0.80 0.118 0.13 0.07 E -0.040 -0.031 -0.050 -0.049 0.140 -16.736 -0.050 0.443 0.300 -0.078 -0.039 -0.019 F -0.003 0.088 0.029 -0.062 0.053 19.845 0.046 -0.069 -0.020 0.029 0.007 0.003 G 0.009 -0.036 0.050 -0.062 0.053 -12.853 -0.003 -0.017 -0.017 -0.006 -0.001 0.000 H -0.005 0.001 -0.033 0.212 0.025 3.541 -0.001 0.005 0.003 0.000 0.000 0.000

[0105] Will refer to Figure 5 A third example of an optical imaging system is described.

[0106] The optical imaging system 300 according to the third example may include a plurality of lenses having refractive power. For example, the optical imaging system 300 may include a first lens 310 , a second lens 320 , a third lens 330 , a fourth lens 340 , a fifth lens 350 , and a sixth lens 360 .

[0107] The first lens 310 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The second lens 320 may have negative refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The third lens 330 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. The fourth lens 340 may have negative refractive power, and its object-side surface may be concave, and its image-side surface may be concave. The fifth lens 350 may have negative refractive power, and its object-side surface may be concave, and its image-side surface may be concave. In addition, an inflection point may be formed on the object-side surface and the image-side surface of the fifth lens 350. The sixth lens 360 may have positive refractive power, and its object-side surface may be convex, and its image-side surface may be concave. In addition, an inflection point may be formed on both surfaces of the sixth lens 360. For example, the object-side surface of the sixth lens may be convex in the paraxial region and may be concave in the region surrounding the paraxial region, and the image-side surface thereof may be concave in the paraxial region and may be convex in the region surrounding the paraxial region.

[0108] The first lens 310, the third lens 330, and the sixth lens 360 may have relatively low refractive indices. For example, the refractive index of the first lens 310, the refractive index of the third lens 330, and the refractive index of the sixth lens 360 may be 1.56 or less. The second lens 320, the fourth lens 340, and the fifth lens 350 may have relatively high refractive indices. For example, the refractive index of the second lens 320, the refractive index of the fourth lens 340, and the refractive index of the fifth lens 350 may be 1.6 or greater. The second lens 320 may have the highest refractive index in the optical imaging system 300. For example, the refractive index of the second lens 320 may be 1.66 or greater. The sixth lens 360 may have the lowest refractive index in the optical imaging system 300. For example, the refractive index of the sixth lens 360 may be 1.54 or less.

[0109] The first lens 310 and the third lens 330 may have the largest Abbe number in the optical imaging system 300. For example, the Abbe number of the first lens 310 and the third lens 330 may be 55 or more. The second lens 320 may have the smallest Abbe number in the optical imaging system 300. For example, the Abbe number of the second lens 320 may be 22 or less.

[0110] The optical imaging system 300 may include a stop ST. For example, the stop ST may be disposed between the second lens 320 and the third lens 330. The stop ST disposed as described above may control the amount of light incident on the imaging surface 380.

[0111] The optical imaging system 300 may include an optical filter 370. For example, the optical filter 370 may be disposed between the sixth lens 360 and the imaging surface 380. The optical filter 370 disposed as described above may block infrared light incident on the imaging surface 380.

[0112] The optical imaging system 300 may include an image sensor. The image sensor may provide an imaging surface 380, and the light refracted by the lens is imaged on the imaging surface 380. The image sensor may convert the optical signal imaged on the imaging surface 380 into an electrical signal.

[0113] The optical imaging system 300 configured as described above may have a low F No. For example, the F No. of the optical imaging system according to the third example may be 1.683.

[0114] The optical imaging system according to the third example may have Figure 6 Table 5 shows the characteristics of the lens of the optical imaging system in the third example, and Table 6 shows the aspherical surface characteristics of the optical imaging system in the third example.

[0115] Table 5

[0116]

[0117] Table 6

[0118] Third Example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of curvature 1.513 32.180 5.763 2.318 9.080 231.495 -45.570 20.349 -427.313 16.111 1.416 1.283 k -0.410 0.996 0.202 -0.694 -0.995 1.000 0.453 -0.291 41.061 -49.945 -2.001 -0.832 A -0.002 0.001 -0.023 0.000 -0.013 -0.002 -0.021 0.052 0.393 0.088 -0.496 -0.397 B 0.047 -0.044 0.000 -0.014 -0.171 0.145 -0.006 -0.421 -0.954 -0.069 0.450 0.271 C -0.093 0.057 0.050 0.062 0.204 -1.638 0.000 0.666 1.100 -0.092 -0.308 -0.162 D 0.093 0.013 0.022 0.062 -0.208 5.718 -0.050 -0.531 -0.88 0.132 0.15 0.07 E -0.056 -0.089 -0.050 -0.036 0.052 -11.903 0.016 0.159 0.413 -0.081 -0.044 -0.019 F 0.008 0.016 -0.026 -0.062 0.053 14.581 -0.048 0.042 -0.085 0.029 0.008 0.003 G 0.009 0.045 0.050 -0.062 0.053 -9.667 0.046 -0.037 0.000 -0.006 -0.001 0.000 H -0.007 -0.021 -0.013 0.185 0.031 2.707 -0.011 0.006 0.002 0.000 0.000 0.000

[0119] Table 7 shows the values ​​of the conditional expressions of the optical imaging systems according to the first to third examples. As seen in Table 7, the optical imaging systems according to the first to third examples can satisfy all the numerical ranges of Conditional Expression 2 to Conditional Expression 6 set forth above.

[0120] Table 7

[0121]

[0122] As explained above, in the examples disclosed herein, an optical imaging system applicable to a small camera module with high performance may be realized.

[0123] Although the present disclosure includes specific examples, it will be apparent after understanding the disclosure of the present application that various changes in form and detail can be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described here will be considered as descriptive only, not for the purpose of limitation. The description of the features or aspects in each example will be considered to be applicable to similar features or aspects in other examples. If the described techniques are performed in a different order, and / or if the components in the described system, architecture, device or circuit are replaced or added in a different manner and / or by other components or their equivalents, suitable results can be obtained. Therefore, the scope of the present disclosure is not limited by specific embodiments but by claims and their equivalents, and all variations within the scope of claims and their equivalents will be understood to be included in the present disclosure.

Claims

1. An optical imaging system, wherein the full field of view (FOV) of the optical imaging system is 75° to 79.8°, the f-number of the optical imaging system is 1.7 or less, and the optical imaging system comprises: A first lens having positive refractive power and a convex object-side surface; The second lens has negative refractive power, a convex object-side surface and a concave image-side surface; The third lens has positive refractive power and a convex object-side surface; a fourth lens element having negative refractive power and a concave image-side surface; a fifth lens element having negative refractive power and a concave image-side surface; and The sixth lens has positive refractive power, a convex object-side surface and a concave image-side surface, The optical imaging system includes a total of six lenses with refractive power, and the first lens to the sixth lens are arranged in sequence from the object side. wherein the third lens has an Abbe number of 55 or greater, and The optical imaging system satisfies TTL / (IMG HT) < 1.5, 20 < R2 / R1, 0 < R8 / R10 < 2.0, 0 < R11 / R12 < 1.2 and 5.0 < D45 / D56 < 10, Wherein, TTL is the distance from the object surface of the first lens to the imaging surface of the optical imaging system, IMG HT is half of the diagonal length of the imaging surface, R1 is the curvature radius of the object surface of the first lens, R2 is the curvature radius of the image surface of the first lens, R8 is the curvature radius of the image surface of the fourth lens, R10 is the curvature radius of the image surface of the fifth lens, R11 is the curvature radius of the object surface of the sixth lens, R12 is the curvature radius of the image surface of the sixth lens, D45 is the distance from the image surface of the fourth lens to the object surface of the fifth lens, and D56 is the distance from the image surface of the fifth lens to the object surface of the sixth lens.

2. The optical imaging system according to claim 1, wherein: The third lens has a concave image-side surface.

3. The optical imaging system according to claim 1, wherein: The second lens has an Abbe number of 22 or less.

4. The optical imaging system according to claim 1, wherein: The first lens has an Abbe number of 55 or more.

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