Optical imaging system, imaging module and electronic device

Abstract

The present application discloses an optical imaging system, an imaging module, and an electronic device. The optical imaging system sequentially includes, from the object side to the image side: a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power, the object side surface of the third lens being concave near the optical axis; and a fourth lens having a positive refractive power, the image side surface of the fourth lens being concave near the optical axis. The optical imaging system satisfies the following conditional expressions: 0.4 < Imgh / f < 1.4, 0.7 < TL / f < 2; where Imgh is half of the image height corresponding to the maximum field of view angle of the optical imaging system, f is the effective focal length of the optical imaging system, and TL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical imaging system. The above optical imaging system ensures the performance of each lens, reduces errors and image degradation phenomena, and improves image resolution by reasonably configuring the surface types and refractive powers of the lenses.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and in particular to an optical imaging system, an imaging module and an electronic device. Background Art

[0002] Camera lenses are increasingly used in electronic products, and with the continuous growth of the consumer electronics industry, the market demand for small imaging modules is increasing. Especially for mobile phone imaging modules, computer imaging modules, or automotive safety impact monitors, users are increasingly demanding product performance, requiring not only good image resolution quality, but also smaller product errors.

[0003] The photosensitive elements of fixed-focus lenses usually use charge coupled devices (CCDs) and complementary metal-oxide semiconductor sensors (CMOSEsnsor). The sensitivity of the photosensitive elements will decay rapidly as the angle of the lens output light increases. Therefore, fixed-focus lenses are usually composed of 3-4 lenses.

[0004] However, the fixed-focus lens using this configuration still has the following defects: the first lens of the existing lens module is a two-way convex lens, and the second lens is a two-way concave lens. The two-way convex lens and the two-way concave lens have the ability to capture too large an image, resulting in unstable imaging quality of the entire optical imaging system. Summary of the invention

[0005] In view of the above, it is necessary to propose an optical imaging system, an imaging module and an electronic device to solve the above problems.

[0006] An embodiment of the present application provides an optical imaging system, which includes, from the object side to the image side, the following:

[0007] The first lens has positive refractive power;

[0008] The second lens has negative refractive power;

[0009] A third lens element has positive refractive power, and the object side surface of the third lens element is concave at the near optical axis; and

[0010] a fourth lens element having negative refractive power, wherein the image side surface of the fourth lens element is concave at the near optical axis;

[0011] The optical imaging system satisfies the following conditional formula:

[0012] 0.4 <Imgh / f<1.4,0.7<TL / f<2;

[0013] Among them, Imgh is half of the image height corresponding to the maximum field angle of the optical imaging system, f is the effective focal length of the optical imaging system, and TL is the distance from the object side of the first lens to the imaging plane of the optical imaging system on the optical axis.

[0014] The above optical imaging system ensures the performance of each lens, reduces errors and image degradation, improves the image resolution of the optical imaging system, and stabilizes the imaging quality of the optical imaging system by reasonably configuring the surface shape and refractive power of each lens. By satisfying the above conditional formula, the optical imaging system can shorten the total optical length of the optical imaging system, making the optical imaging system thinner and smaller.

[0015] In some embodiments, the object-side surface and the image-side surface of the second lens, the object-side surface and the image-side surface of the third lens, and the object-side surface and the image-side surface of the fourth lens are all aspherical surfaces.

[0016] In some embodiments, the object-side surface of the first lens is convex at the near optical axis, and the image-side surface of the first lens is convex at the near optical axis.

[0017] In some embodiments, the optical imaging system satisfies the following condition:

[0018] 0.6 <TL2 / f<1.8;

[0019] Wherein, TL2 is the distance from the object side of the second lens to the imaging surface of the optical imaging system on the optical axis.

[0020] In some embodiments, the optical imaging system satisfies the following condition:

[0021] 0.3 <TL3 / f<1;

[0022] Wherein, TL3 is the distance from the object side surface of the third lens to the imaging surface of the optical imaging system on the optical axis.

[0023] In some embodiments, the optical imaging system satisfies the following condition:

[0024] 0.1 <TL4 / f<0.5;

[0025] Wherein, TL4 is the distance from the object side surface of the fourth lens to the imaging surface of the optical imaging system on the optical axis.

[0026] In some embodiments, the optical imaging system satisfies the following conditional formula:

[0027] 1.1 <f / EPD<3.9;

[0028] Wherein, EPD is the entrance pupil diameter of the optical imaging system.

[0029] In some embodiments, the optical imaging system satisfies the following condition:

[0030] 0.42 <V1 / (V2+V3+V4)<0.44;

[0031] Among them, V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, V3 is the dispersion coefficient of the third lens, and V4 is the dispersion coefficient of the fourth lens.

[0032] An embodiment of the present application further provides an imaging module, including:

[0033] An optical imaging system as described above; and

[0034] A photosensitive element is arranged on the image side of the optical imaging system.

[0035] An embodiment of the present application further provides an electronic device, including:

[0036] housing; and

[0037] As described above, the imaging module is arranged on the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure of the optical imaging system provided in the first embodiment of the present application.

[0039] Figure 2 It is a schematic diagram of field curvature and distortion of the optical imaging system in the first embodiment of the present application.

[0040] Figure 3 It is a schematic diagram of the structure of the optical imaging system provided in the second embodiment of the present application.

[0041] Figure 4 It is a schematic diagram of field curvature and distortion of the optical imaging system in the second embodiment of the present application.

[0042] Figure 5 It is a schematic diagram of the structure of the optical imaging system provided in the third embodiment of the present application.

[0043] Figure 6 It is a schematic diagram of field curvature and distortion of the optical imaging system in the third embodiment of the present application.

[0044] Figure 7 It is a schematic diagram of the structure of the optical imaging system provided in the fourth embodiment of the present application.

[0045] Figure 8 It is a schematic diagram of field curvature and distortion of the optical imaging system in the fourth embodiment of the present application.

[0046] Fig. 9 It is a schematic diagram of the structure of the optical imaging system provided in the fifth embodiment of the present application.

[0047] Fig.10 It is a schematic diagram of field curvature and distortion of the optical imaging system in the fifth embodiment of the present application.

[0048] Fig.11 It is a schematic diagram of the structure of the optical imaging system provided in the sixth embodiment of the present application.

[0049] Fig.12 It is a schematic diagram of field curvature and distortion of the optical imaging system in the sixth embodiment of the present application.

[0050] Fig.13 It is a structural schematic diagram of the imaging module provided in the seventh embodiment of the present application.

[0051] Fig.14 It is a schematic diagram of the structure of the electronic device provided in the eighth embodiment of the present application.

[0052] Main component symbols

[0053] Electronic device 1000

[0054] Image acquisition module 100

[0055] Optical imaging system 10

[0056] First lens L1

[0057] Second lens L2

[0058] The third lens L3

[0059] The fourth lens L4

[0060] Filter L5

[0061] Object side S1, S3, S5, S7, S9

[0062] Like the side S2, S4, S6, S8, S10

[0063] Aperture STO

[0064] Imaging Surface IMA

[0065] Photosensitive element 20

[0066] Housing 200 DETAILED DESCRIPTION

[0067] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application and should not be construed as limiting the present application.

[0068] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means three or more unless otherwise specifically defined.

[0069] Please refer to Figure 1 , a first embodiment of the present application provides an optical imaging system 10, which successively includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 from the object side to the image side. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all approximately meniscus lenses.

[0070] The first lens L1 has a positive refractive power and has an object side surface S1 and an image side surface S2; the second lens L2 has a negative refractive power and has an object side surface S3 and an image side surface S4; the third lens L3 has a positive refractive power and has an object side surface S5 and an image side surface S6. The object side surface S5 of the third lens L3 is concave near the optical axis; the fourth lens L4 has a positive refractive power and has an object side surface S7 and an image side surface S8. The image side surface of the fourth lens L4 is concave near the optical axis.

[0071] The optical imaging system 10 satisfies the following conditional expressions:

[0072] 0.4 < Imgh / f < 1.4, 0.7 < TL / f < 2; where Imgh is half of the image height corresponding to the maximum field of view angle of the optical imaging system 10, f is the effective focal length of the optical imaging system 10, and TL is the distance from the object side surface of the first lens L1 to the imaging surface of the optical imaging system 10 on the optical axis.

[0073] By reasonably controlling the values of Imgh / f and TL / f, the above-mentioned optical imaging system 10 can improve the image resolution of the optical imaging system 10, the imaging quality is stable, the total optical length of the optical imaging system 10 can be shortened, and the optical imaging system 10 can be made thinner, lighter, and smaller.

[0074] The optical imaging system 10 of this embodiment can ensure the performance of each lens, reduce imaging errors and image degradation, and improve the image resolution of the optical imaging system 10 by reasonably configuring the refractive power and surface shape of each lens.

[0075] In some embodiments, the optical imaging system 10 further includes a stop STO. The stop STO may be disposed on the surface of any lens, or disposed before the first lens L1, or disposed between any two lenses, or disposed on the image side surface S8 of the fourth lens L4. Figure 1 , the stop STO is disposed on the object-side surface S1 of the first lens L1.

[0076] In some embodiments, the optical imaging system 10 further includes a filter L5, which has an object side surface S9 and an image side surface S10. The filter L5 is disposed on the image side of the fourth lens L4 to filter out light of other wavelengths such as visible light and only allow infrared light to pass, so that the optical imaging system 10 can also form images in dim environments and other special application scenarios.

[0077] It can be understood that in other embodiments, the filter L5 in the optical imaging system 10 can also be used to filter out invisible light such as infrared light, and only allow visible light to pass through to adapt to the human eye's vision, so that the optical imaging system 10 can have higher pixels and good imaging quality when used in daytime with sufficient light.

[0078] In some embodiments, the object-side surface S3 and the image-side surface S4 of the second lens L2 are both aspherical surfaces, the object-side surface S5 and the image-side surface S6 of the third lens L3 are both aspherical surfaces, and the object-side surface S7 and the image-side surface S8 of the fourth lens L4 are both aspherical surfaces.

[0079] In this way, most of the spherical aberration of the optical imaging system 10 can be eliminated, thereby improving the imaging quality of the optical imaging system 10 .

[0080] In some embodiments, the object-side surface S1 of the first lens L1 is convex at the near optical axis, and the image-side surface S2 of the first lens L1 is convex at the near optical axis.

[0081] In this way, by reasonably configuring the surface shape of the first lens L1, the performance of the first lens L1 can be ensured, and the image resolution of the optical imaging system 10 can be improved.

[0082] In some embodiments, the second lens L2 , the third lens L3 , and the fourth lens L4 are all plastic lenses.

[0083] In this way, each lens of the optical imaging system 10 is easier to manufacture, which can effectively reduce costs and improve product bonding yield.

[0084] In some embodiments, the optical imaging system 10 satisfies the following conditional formula:

[0085] 0.6 < TL2 / f < 1.8; where TL2 is the distance on the optical axis from the object side surface S3 of the second lens L2 to the imaging surface IMA of the optical imaging system 10.

[0086] Thus, by satisfying the above range for TL2 / f, it is beneficial to shorten the overall optical length of the optical imaging system 10.

[0087] In some embodiments, the optical imaging system 10 satisfies the following conditional formula:

[0088] 0.3 < TL3 / f < 1; where TL3 is the distance on the optical axis from the object side surface S5 of the third lens L3 to the imaging surface IMA of the optical imaging system 10.

[0089] Thus, by satisfying the above range for TL3 / f, it is beneficial to shorten the overall optical length of the optical imaging system 10.

[0090] In some embodiments, the optical imaging system 10 satisfies the following conditional formula:

[0091] 0.1 < TL4 / f < 0.5; where TL4 is the distance on the optical axis from the object side surface S7 of the fourth lens L4 to the imaging surface IMA of the optical imaging system 10.

[0092] Thus, by satisfying the above range for TL4 / f, it is beneficial to shorten the overall optical length of the optical imaging system 10.

[0093] In some embodiments, the optical imaging system 10 satisfies the following conditional formula:

[0094] 1.1 < f / EPD < 3.9; where EPD is the entrance pupil diameter of the optical imaging system 10.

[0095] Thus, by satisfying the above range for f / EPD, it is beneficial to control the light incident amount and the f-number of the optical imaging system 10, enabling the optical imaging system 10 to have excellent image resolution for an object, thereby improving the imaging quality of the optical imaging system 10.

[0096] In some embodiments, the optical imaging system 10 satisfies the following conditional formula:

[0097] 0.42 < V1 / (V2 + V3 + V4) < 0.44; where V1 is the dispersion coefficient of the first lens L1, V2 is the dispersion coefficient of the second lens L2, V3 is the dispersion coefficient of the third lens L3, and V4 is the dispersion coefficient of the fourth lens L4.

[0098] Thus, by V1 / (V2+V3+V4) satisfying the above range, the optical imaging system 10 can achieve a good balance between chromatic aberration correction and astigmatism correction, thereby improving the imaging quality of the optical imaging system 10.

[0099] First embodiment

[0100] See also Figure 1 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0101] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0102] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is concave at the near optical axis, the image side surface S4 of the second lens L2 is convex at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is convex at the near optical axis, the object side surface S7 of the fourth lens L4 is concave at the near optical axis, and the image side surface S8 of the fourth lens L4 is convex at the near optical axis.

[0103] Among them, the dispersion coefficient of the first lens L1 is 55.978, the dispersion coefficient of the second lens L2 is 20.373, the dispersion coefficient of the third lens L3 is 55.978, and the dispersion coefficient of the fourth lens L4 is 55.978.

[0104] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0105] Table 1 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the curvature radius, thickness and semi-diameter are all millimeters (mm).

[0106] Table 1

[0107]

[0108] Wherein, f is the effective focal length of the optical imaging system 10, TL is the distance from the object-side surface S1 of the first lens L1 to the imaging surface IMA of the optical imaging system 10 on the optical axis, TL2 is the distance from the object-side surface S3 of the second lens L2 to the imaging surface IMA of the optical imaging system 10 on the optical axis, TL3 is the distance from the object-side surface S5 of the third lens L3 to the imaging surface IMA of the optical imaging system 10 on the optical axis, and TL4 is the distance from the object-side surface S7 of the fourth lens L4 to the imaging surface IMA of the optical imaging system 10 on the optical axis.

[0109] In this embodiment, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all aspherical surfaces, and the surface shape Z of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0110]

[0111] Wherein, Z is the distance between any point on the aspheric surface and the vertex of the surface parallel to the optical axis, r is the perpendicular distance from any point on the aspheric surface to the optical axis, c is the vertex curvature (the inverse of the radius of curvature), k is the cone constant, Ai is the correction coefficient of the i-th order aspheric surface, and Table 2 shows the high-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspheric lens S1-S8 in the first embodiment.

[0112] Table 2

[0113]

[0114] Figure 2 The field curvature and distortion curves of the optical imaging system 10 of the first embodiment are shown. The field curvature curve represents the meridional image plane curvature and the sagittal image plane curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Figure 2 It can be seen that the optical imaging system 10 provided in the first embodiment can achieve good imaging quality.

[0115] Second embodiment

[0116] See also Figure 3 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0117] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0118] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is concave at the near optical axis, the image side surface S4 of the second lens L2 is convex at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is convex at the near optical axis, the object side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image side surface S8 of the fourth lens L4 is concave at the near optical axis.

[0119] Among them, the dispersion coefficient of the first lens L1 is 55.978, the dispersion coefficient of the second lens L2 is 20.373, the dispersion coefficient of the third lens L3 is 55.978, and the dispersion coefficient of the fourth lens L4 is 55.978.

[0120] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0121] Table 3 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the radius of curvature, thickness and semi-diameter are all millimeters (mm).

[0122] Table 3

[0123]

[0124]

[0125] Table 4 shows the higher-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical lens S1-S8 in the second embodiment.

[0126] Table 4

[0127]

[0128] Figure 4 The field curvature and distortion curves of the optical imaging system 10 of the second embodiment are shown. The field curvature curve represents the meridional image plane curvature and the sagittal image plane curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Figure 4 It can be seen that the optical imaging system 10 provided in the second embodiment can achieve good imaging quality.

[0129] Third embodiment

[0130] See also Figure 5 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0131] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0132] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is concave at the near optical axis, the image side surface S4 of the second lens L2 is convex at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is convex at the near optical axis, the object side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image side surface S8 of the fourth lens L4 is concave at the near optical axis.

[0133] Among them, the dispersion coefficient of the first lens L1 is 55.978, the dispersion coefficient of the second lens L2 is 20.373, the dispersion coefficient of the third lens L3 is 55.978, and the dispersion coefficient of the fourth lens L4 is 55.978.

[0134] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0135] Table 5 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the radius of curvature, thickness and semi-diameter are all millimeters (mm).

[0136] Table 5

[0137]

[0138] Table 6 shows the higher-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical lens S1-S8 in the third embodiment.

[0139] Table 6

[0140]

[0141] Figure 6 The field curvature and distortion curves of the optical imaging system 10 of the third embodiment are shown. The field curvature curve represents the meridional image plane curvature and the sagittal image plane curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Figure 6 It can be seen that the optical imaging system 10 provided in the third embodiment can achieve good imaging quality.

[0142] Fourth embodiment

[0143] See also Figure 7 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0144] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0145] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is convex at the near optical axis, the image side surface S4 of the second lens L2 is concave at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is convex at the near optical axis, the object side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image side surface S8 of the fourth lens L4 is concave at the near optical axis.

[0146] Among them, the dispersion coefficient of the first lens L1 is 55.978, the dispersion coefficient of the second lens L2 is 20.373, the dispersion coefficient of the third lens L3 is 55.978, and the dispersion coefficient of the fourth lens L4 is 55.978.

[0147] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0148] Table 7 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the radius of curvature, thickness and semi-diameter are all millimeters (mm).

[0149] Table 7

[0150]

[0151] Table 8 shows the higher-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical lens S1-S8 in the fourth embodiment.

[0152] Table 8

[0153]

[0154]

[0155] Figure 8 The field curvature and distortion curves of the optical imaging system 10 of the fourth embodiment are shown. The field curvature curve represents the meridional image plane curvature and the sagittal image plane curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Figure 8 It can be seen that the optical imaging system 10 provided in the fourth embodiment can achieve good imaging quality.

[0156] Fifth embodiment

[0157] See also Fig. 9 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0158] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0159] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is concave at the near optical axis, the image side surface S4 of the second lens L2 is convex at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is convex at the near optical axis, the object side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image side surface S8 of the fourth lens L4 is concave at the near optical axis.

[0160] Among them, the dispersion coefficient of the first lens L1 is 56.000, the dispersion coefficient of the second lens L2 is 20.400, the dispersion coefficient of the third lens L3 is 56.000, and the dispersion coefficient of the fourth lens L4 is 56.000.

[0161] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0162] Table 9 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the radius of curvature, thickness and semi-diameter are all millimeters (mm).

[0163] Table 9

[0164]

[0165]

[0166] Table 10 shows the higher-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical lens S1-S8 in the fifth embodiment.

[0167] Table 10

[0168]

[0169] Fig.10 The field curvature and distortion curves of the optical imaging system 10 of the fifth embodiment are shown. The field curvature curve represents the meridional image plane curvature and the sagittal image plane curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Fig.10 It can be seen that the optical imaging system 10 provided in the fifth embodiment can achieve good imaging quality.

[0170] Sixth embodiment

[0171] See also Fig.11 In the optical imaging system 10 of this embodiment, from the object side to the image side, it includes an aperture STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power and a filter L5.

[0172] The materials of the first lens L1 , the second lens L2 , the third lens L3 and the fourth lens L4 are all made of plastic, and the material of the filter L5 is glass.

[0173] The object side surface S1 of the first lens L1 is convex at the near optical axis, the image side surface S2 of the first lens L1 is convex at the near optical axis, the object side surface S3 of the second lens L2 is convex at the near optical axis, the image side surface S4 of the second lens L2 is convex at the near optical axis, the object side surface S5 of the third lens L3 is concave at the near optical axis, the image side surface S6 of the third lens L3 is concave at the near optical axis, the object side surface S7 of the fourth lens L4 is concave at the near optical axis, and the image side surface S8 of the fourth lens L4 is concave at the near optical axis. The image side surface S4 of the second lens L2 is bonded to the object side surface S5 of the third lens L3.

[0174] Among them, the dispersion coefficient of the first lens L1 is 56.000, the dispersion coefficient of the second lens L2 is 45.400, the dispersion coefficient of the third lens L3 is 27.500, and the dispersion coefficient of the fourth lens L4 is 56.000.

[0175] When the optical imaging system 10 is used for imaging, the light emitted or reflected by the object enters the optical imaging system 10 from the object side, and passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the filter L5 in sequence, and finally converges on the imaging surface IMA.

[0176] Table 11 shows a table of characteristics of the optical imaging system 10 of this embodiment, wherein the reference wavelength of the focal length, refractive index and Abbe number is 558 nm, and the units of the radius of curvature, thickness and semi-diameter are all millimeters (mm).

[0177] Table 11

[0178]

[0179]

[0180] Table 12 shows the higher-order coefficients K, A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspherical lens S1-S8 in the sixth embodiment.

[0181] Table 12

[0182]

[0183] Fig.12The field curvature and distortion curves of the optical imaging system 10 of the sixth embodiment are shown. The field curvature curve represents the meridional image curvature and the sagittal image curvature, wherein the maximum values ​​of the sagittal field curvature and the meridional field curvature are both less than 0.1 mm, which are well compensated; the distortion curve represents the distortion magnitude values ​​corresponding to different field angles, wherein the maximum distortion is less than 1%, which is also well corrected. Fig.12 It can be seen that the optical imaging system 10 provided in the sixth embodiment can achieve good imaging quality.

[0184] Table 13 shows the values ​​of Imgh / f, TL / f, TL2 / f, TL3 / f, TL4 / f, f / EPD and V1 / (V2+V3+V4) in the optical imaging system 10 of the first to sixth embodiments.

[0185] Table 13

[0186] Example First embodiment Second embodiment Third embodiment Fourth embodiment Fifth embodiment Sixth embodiment Imgh / f 0.693 0.701 0.726 0.796 0.694 0.694 TL / f 1.326 1.327 1.340 1.122 1.525 1.734 TL2 / f 1.151 1.137 1.142 1.030 1.283 1.253 TL3 / f 0.741 0.740 0.731 0.533 0.984 0.561 TL4 / f 0.538 0.536 0.519 0.379 0.712 0.179 f / EPD 1.994 1.881 1.815 2.051 1.993 2.344 V1 / (V2+V3+V4) 0.423 0.423 0.423 0.423 0.423 0.434

[0187] See also Fig.13 The seventh embodiment of the present application provides an imaging module 100 , including an optical imaging system 10 and a photosensitive element 20 , wherein the photosensitive element 20 is disposed on the image side of the optical imaging system 10 .

[0188] Specifically, the photosensitive element 20 may be a complementary metal oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD).

[0189] The optical imaging system 10 in the imaging module 100 of this embodiment can improve the image resolution of the optical imaging system 10 by reasonably controlling the value of Imgh / f and the value of TL / f, and the imaging quality is stable, and the total optical length of the optical imaging system 10 can be shortened, making the optical imaging system 10 thinner and smaller. The optical imaging system 10 can ensure the performance of each lens, reduce imaging errors and image degradation, and improve the image resolution of the optical imaging system 10 by reasonably configuring the refractive power and surface shape of each lens.

[0190] See also Fig.14 The eighth embodiment of the present application provides an electronic device 1000 , including a housing 200 and an imaging module 100 , wherein the imaging module 100 is disposed in the housing 200 .

[0191] The electronic device 1000 of this embodiment includes but is not limited to smart phones, tablet computers, laptop computers, e-book readers, portable multimedia players (PMPs), portable phones, video phones, digital still cameras, mobile medical devices, wearable devices, and other electronic devices 1000 that support imaging.

[0192] The optical imaging system 10 in the electronic device 1000 of this embodiment can improve the image resolution of the optical imaging system 10 by reasonably controlling the value of Imgh / f and the value of TL / f, and the imaging quality is stable, and the total optical length of the optical imaging system 10 can be shortened, making the optical imaging system 10 thinner and smaller. The optical imaging system 10 can ensure the performance of each lens, reduce imaging errors and image degradation, and improve the image resolution of the optical imaging system 10 by reasonably configuring the refractive power and surface shape of each lens.

[0193] It is obvious to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present application.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. An optical imaging system, characterized in that: From the object side to the image side, it includes: The first lens has positive refractive power; The second lens has negative refractive power; A third lens element has positive refractive power, and the object side surface of the third lens element is concave at the near optical axis; and a fourth lens element having positive refractive power, wherein the image side surface of the fourth lens element is concave at the near optical axis; The optical imaging system satisfies the following conditional formula: 0.4 <Imgh / f<1.4,0.7<TL / f<2,0.42<V1 / (V2+V3+V4)<0.44; Among them, Imgh is half of the image height corresponding to the maximum field of view angle of the optical imaging system, f is the effective focal length of the optical imaging system, TL is the distance from the object side of the first lens to the imaging surface of the optical imaging system on the optical axis, V1 is the dispersion coefficient of the first lens, V2 is the dispersion coefficient of the second lens, V3 is the dispersion coefficient of the third lens, and V4 is the dispersion coefficient of the fourth lens.

2. The optical imaging system according to claim 1, wherein: The object side surface and the image side surface of the second lens, the object side surface and the image side surface of the third lens, and the object side surface and the image side surface of the fourth lens are all aspherical surfaces.

3. The optical imaging system according to claim 1, wherein: The object side surface of the first lens is a convex surface at the near optical axis, and the image side surface of the first lens is a convex surface at the near optical axis.

4. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following conditional formula: 0.6 <TL2 / f<1.8; Wherein, TL2 is the distance from the object side of the second lens to the imaging surface of the optical imaging system on the optical axis.

5. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following conditional formula: 0.3 <TL3 / f<1; Wherein, TL3 is the distance from the object side surface of the third lens to the imaging surface of the optical imaging system on the optical axis.

6. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following conditional formula: 0.1 <TL4 / f<0.8; Wherein, TL4 is the distance from the object side surface of the fourth lens to the imaging surface of the optical imaging system on the optical axis.

7. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following conditional formula: 1.1 <f / EPD<3.9; Wherein, EPD is the entrance pupil diameter of the optical imaging system.

8. An imaging module, characterized in that: include: The optical imaging system according to any one of claims 1 to 7; and A photosensitive element is arranged on the image side of the optical imaging system.

9. An electronic device, characterized in that: include: case; and The imaging module as described in claim 8, wherein the imaging module is disposed in the housing.

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