Optical imaging system, imaging device, and electronic device

Abstract

The present invention provides an optical imaging system, an imaging device, and an electronic device. The optical imaging system provided by the present invention sequentially includes, from the object side to the image side: a first lens with positive optical power; a second lens with optical power; a third lens with optical power; and a fourth lens with optical power; wherein, the optical imaging system satisfies the following conditional formula: TTL ≤ 2.644 mm; wherein, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis. The total length of the optical imaging system of the present invention is less than or equal to 2.644 mm, and it can well meet the requirement of the ultra-thinning of the camera.

Description

Technical Field

[0001] The present invention relates to optical imaging technology, and particularly to an optical imaging system, an image capturing device, and an electronic device. Background Art

[0002] With the development of technologies such as mobile phone face unlocking, automobile autonomous driving, human-machine interface and gaming, industrial machine vision and measurement, and security monitoring, people require these devices to have functions such as three-dimensional (3D) face recognition, object restoration, and mobile payment. The realization of these functions places higher requirements on the technology of cameras. The time-of-flight (TOF) imaging technology applied to cameras can well realize the 3D face recognition function of cameras and has good object restoration performance. However, the total length of the existing camera systems based on TOF imaging is too long and cannot meet the requirements of these devices for ultra-thin cameras. Summary of the Invention

[0003] In view of this, an embodiment of the present invention provides an optical imaging system with a short total length, which can well meet the requirements of cameras for ultra-thinness.

[0004] It is also necessary to provide an image capturing device using the above optical imaging system.

[0005] In addition, it is necessary to provide an electronic device using the above image capturing device.

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

[0007] A first lens with a positive focal power;

[0008] A second lens with a focal power;

[0009] A third lens with a focal power; and

[0010] A fourth lens with a focal power;

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

[0012] TTL ≤ 2.644 mm;

[0013] Wherein, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis.

[0014] The total length of the optical imaging system of the present invention is fully compressed and can well meet the requirements of ultra-thinness.

[0015] Among them, the object side of the first lens near the optical axis is a convex surface; the image side near the optical axis is a concave surface. The convex surface at the object side near the optical axis is more conducive to the convergence of light, enabling the first lens to have sufficient positive optical power, thereby shortening the total length of the optical imaging system. The image side cooperates with the object side to converge light.

[0016] Among them, the object side of the third lens near the optical axis is a concave surface; the image side near the optical axis is a convex surface. The convex surface at the image side near the optical axis can ensure the ability of the third lens to correct aberrations.

[0017] Among them, the object side of the fourth lens near the optical axis is a convex surface; the image side near the optical axis is a concave surface. The concave surface at the image side near the optical axis of the fourth lens helps to correct the field curvature of the optical imaging system, suppress the excessive increase in the incident angle of the chief ray in the off-axis field of view, and at the same time correct the aberrations in the off-axis field of view.

[0018] Among them, at least one inflection point is provided on at least one of the object side and the image side of the fourth lens. The inflection point can be used to correct the aberrations in the off-axis field of view, suppress the incident angle of light to the imaging surface, and can more accurately match the photosensitive element.

[0019] Among them, the optical imaging system satisfies the following conditional formula:

[0020] 0.8 < tan(FOV / 2) < 1.0;

[0021] Among them, FOV is the maximum field of view angle of the optical imaging system.

[0022] When tan(FOV / 2) is less than 0.8, the field of view angle of the optical imaging system is too small to obtain a wide image, and it will make the effective focal length of the optical imaging system longer, which is not conducive to lens length compression. When 0.8 < tan(FOV / 2) < 1.0, the image range of the optical imaging system can be expanded.

[0023] Among them, the optical imaging system satisfies the following conditional formula:

[0024] FNO ≤ 1.6;

[0025] Among them, FNO is the aperture number of the optical imaging system.

[0026] When FNO ≤ 1.6, the optical imaging system has a larger light flux and a higher relative brightness.

[0027] Among them, the optical imaging system satisfies the following conditional formula:

[0028] FNO ≤ 1.3;

[0029] Among them, FNO is the aperture number of the optical imaging system.

[0030] When FNO ≤ 1.3, the optical imaging system has a larger light flux and a higher relative brightness.

[0031] Among them, the optical imaging system satisfies the following conditional formula:

[0032] 19 < Vd1 < 25;

[0033] 19 < Vd2 < 25;

[0034] 19 < Vd3 < 25;

[0035] 19 < Vd4 < 25;

[0036] Among them, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and Vd4 is the Abbe number of the fourth lens.

[0037] When Vd1, Vd2, Vd3, and Vd4 are all greater than 19 and less than 25, it is beneficial for the optical imaging system to obtain a higher modulation transfer function and improve the imaging quality of the optical imaging system.

[0038] Among them, the optical imaging system satisfies the following conditional formula:

[0039] 0.5 < CT2 / CT3 < 1.5;

[0040] Among them, CT2 is the central thickness of the second lens, and CT3 is the central thickness of the third lens.

[0041] When 0.5 < CT2 / CT3 < 1.5, the assembly of the optical imaging system can be made more stable.

[0042] Among them, the optical imaging system satisfies the following conditional formula:

[0043] 0 < R5 / R6 < 2.2;

[0044] Among them, R5 is the curvature radius of the object side of the second lens on the optical axis, and R6 is the curvature radius of the image side of the second lens on the optical axis.

[0045] When 0 < R5 / R6 < 2.2, the shapes of the object side and the image side of the second lens are similar, the forming is more uniform, and the object side and the image side are bent on the same side, which is beneficial to improving the resolution of the optical imaging system.

[0046] Among them, the optical imaging system satisfies the following conditional formula:

[0047] 0.18 < R7 / R8 < 1.1;

[0048] Wherein, R7 is the curvature radius of the object side surface of the third lens on the optical axis, and R8 is the curvature radius of the image side surface of the third lens on the optical axis.

[0049] When 0.18 < R7 / R8 < 1.1, the object side surface and the image side surface of the third lens are similar in shape, the forming is more uniform, and the object side surface and the image side surface are bent on the same side, which is beneficial to improving the resolution of the optical imaging system.

[0050] Wherein, the optical imaging system satisfies the following conditional formula:

[0051] 0.4 < R10 / f < 0.8;

[0052] Wherein, R10 is the curvature radius of the image side surface of the fourth lens on the optical axis, and f is the effective focal length of the optical imaging system.

[0053] When 0.4 < R10 / f < 0.8, the image side surface of the fourth lens is concave near the optical axis and convex at the circumference, which helps to correct the field curvature of the optical imaging system, suppress the excessive increase of the principal ray incident angle in the off-axis field of view, and at the same time correct the aberration of the off-axis field of view.

[0054] Wherein, the optical imaging system satisfies the following conditional formula:

[0055] -1 < f1 / f23 < 0.5;

[0056] Wherein, f1 is the effective focal length of the first lens, and f23 is the combined focal length of the second lens and the third lens.

[0057] By providing most of the positive optical power with the first lens and reasonably configuring the optical power of the second lens and the third lens, the positive spherical aberration generated by the first lens can be corrected, and a small part of positive optical power can be compensated for the optical imaging system, and the optical imaging system has a high imaging quality.

[0058] An embodiment of the present invention further provides an image pickup device, which includes:

[0059] The above-mentioned optical imaging system; and

[0060] A photosensitive element, and the photosensitive element is located on the image side of the optical imaging system.

[0061] The orientation device of the present invention is small in thickness and can be used to prepare an ultra-thin camera.

[0062] The image pickup device of the present invention has a wide focusing range and imaging quality while ensuring miniaturization.

[0063] An embodiment of the present invention further provides an electronic device, which includes:

[0064] A device main body; and

[0065] The above imaging device is mounted on the device body.

[0066] The camera of the electronic device of the present invention has a small thickness, which is beneficial to reducing the volume of the electronic device.

[0067] Therefore, the total length of the optical imaging system of the present invention is less than or equal to 2.644 mm. The small total length of the system can well meet the requirement of ultra-thinning of the camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] To more clearly illustrate the structural features and functions of the present invention, the following will describe it in detail in combination with the drawings and specific embodiments.

[0069] Figure 1-1 It is a schematic structural diagram of the optical imaging system according to the first embodiment of the present invention.

[0070] Figure 1-2 From left to right are the spherical aberration, astigmatism and distortion curves of the optical imaging system according to the first embodiment of the present invention.

[0071] Figure 2-1 It is a schematic structural diagram of the optical imaging system according to the second embodiment of the present invention.

[0072] Figure 2-2 From left to right are the spherical aberration, astigmatism and distortion curves of the optical imaging system according to the second embodiment of the present invention.

[0073] Figure 3-1 It is a schematic structural diagram of the optical imaging system according to the third embodiment of the present invention.

[0074] Figure 3-2 From left to right are the spherical aberration, astigmatism and distortion curves of the optical imaging system according to the third embodiment of the present invention.

[0075] Figure 4-1 It is a schematic structural diagram of the optical imaging system according to the fourth embodiment of the present invention.

[0076] Figure 4-2 From left to right are the spherical aberration, astigmatism and distortion curves of the optical imaging system according to the fourth embodiment of the present invention.

[0077] Figure 5-1 It is a schematic structural diagram of the optical imaging system according to the fifth embodiment of the present invention.

[0078] Figure 5-2 From left to right are the spherical aberration, astigmatism and distortion curves of the optical imaging system according to the fifth embodiment of the present invention.

[0079] Figure 6-1 It is a schematic structural diagram of the optical imaging system according to the sixth embodiment of the present invention.

[0080] Figure 6-2 From left to right are the spherical aberration, astigmatism, and distortion curve graphs of the optical imaging system according to the sixth embodiment of the present invention.

[0081] Figure 7 Schematic structural diagram of the imaging device according to an embodiment of the present invention.

[0082] Figure 8 Schematic structural diagram of the electronic device according to an embodiment of the present invention. Specific embodiments

[0083] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0084] Please refer to Figure 1-1 , Figure 2-1 , Figure 3-1 , Figure 4-1 , Figure 5-1 and Figure 6-1 , the optical imaging system 100 according to an embodiment of the present invention is suitable for infrared band imaging and can be applied to the lenses of camera devices such as computers, mobile phones, tablet computers, vehicles, monitoring, security, medical, game consoles, robots, etc. It sequentially includes a first lens L1 with positive optical power, a second lens L2 with optical power, a third lens L3 with optical power, a fourth lens L4 with optical power, and an imaging surface 50 from the object side to the image side. Among them, the optical imaging system 100 satisfies the following conditional expressions:

[0085] TTL ≤ 2.644 mm;

[0086] Among them, TTL is the distance from the object side surface of the first lens L1 to the imaging surface 50 on the optical axis, that is, the total length of the optical imaging system 100.

[0087] More specifically, TTL can be 2.3 mm, 2.35 mm, 2.4 mm, 2.45 mm, 2.5 mm, 2.55 mm, 2.6 mm, 2.64 mm.

[0088] When TTL ≤ 2.644 mm, the total length of the optical imaging system 100 is sufficiently compressed, and it can well meet the requirements of the camera for ultra-thinness.

[0089] The term "focal power" in the present invention characterizes the ability of an optical system to deflect light rays.

[0090] The total length of the optical imaging system 100 of the present invention is less than or equal to 2.644 mm, which can well meet the requirements of the thinning of the camera.

[0091] Optionally, the first lens L1 is made of glass or plastic, and has an object side S1 and an image side S2. The object side S1 is convex near the optical axis; it can be convex or concave at the circumference. The image side S2 is concave near the optical axis, and can be convex or concave at the circumference. The object side S101 is convex near the optical axis, which is more conducive to the convergence of light, so that the first lens L1 has sufficient positive optical power, thereby shortening the total length of the optical imaging system 100, and the image side S2 cooperates with the object side to converge light.

[0092] Optionally, the second lens L2 is made of glass or plastic, and has an object side S3 and an image side S4. The second lens L2 can have positive optical power or negative optical power. The object side S3 can be convex or concave near the optical axis; it can be convex or concave at the circumference. The image side S4 can be convex or concave near the optical axis; it can be convex or concave at the circumference.

[0093] Optionally, the third lens L3 is made of glass or plastic, and has an object side S5 and an image side S6. The third lens L3 can have positive optical power or negative optical power. The object side S5 is concave near the optical axis; it can be convex or concave at the circumference. The image side S6 is convex near the optical axis, and can be convex or concave at the circumference. The image side S6 of the third lens L3 is convex near the optical axis, which can ensure the ability of the third lens to correct aberrations.

[0094] Optionally, the fourth lens L4 is made of glass or plastic, and has an object side S7 and an image side S8. The fourth lens L4 can have positive optical power or negative optical power. The object side S7 is convex near the optical axis; it can be convex or concave at the circumference. The image side S8 is concave near the optical axis, and can be convex or concave at the circumference. When the image side S8 of the fourth lens L4 is concave near the axis and convex at the circumference, this helps to correct the field curvature of the optical imaging system 100, suppress the excessive increase of the principal ray incident angle in the off-axis field of view, and at the same time correct the aberrations in the off-axis field of view.

[0095] In some embodiments, at least one inflection point is provided on at least one of the object side S7 and the image side S8 of the fourth lens L4. The "inflection point" refers to the inflection point where the radius of curvature changes from positive to negative or from negative to positive. The inflection point can be used to correct the aberrations in the off-axis field of view, suppress the incident angle of light to the imaging surface 50, and can more accurately match the photosensitive element (please refer to Figure 7 and the following embodiments).

[0096] In some embodiments, among the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, there are glass lenses and plastic lenses. For example, the first lens L1 is a glass lens, and the second lens L2, the third lens L3, and the fourth lens L4 are all plastic lenses. By setting the first lens L1 closest to the object side as a glass lens, it can better withstand the influence of the environmental temperature on the object side. At the same time, since the second lens L2, the third lens L3, and the fourth lens L4 are plastic lenses, it can well reduce the weight of the optical imaging system 100 and lower the production cost. In addition, the optical imaging system 100 with a mixture of glass lenses and plastic lenses has a higher light transmittance and more stable chemical properties compared to an optical imaging system that only includes plastic lenses, and can improve the imaging quality under different light and dark contrast ratios.

[0097] In some embodiments, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all aspherical lenses. Aspherical lenses are beneficial for correcting the aberration of the optical imaging system 100 and improving the imaging quality of the optical imaging system 100. They can be easily made into shapes other than spherical shapes, obtaining more control variables, having the advantage of achieving good imaging with a smaller number of lenses, and thus reducing the number of lenses to meet miniaturization requirements. An "aspherical lens" refers to a lens with at least one aspherical surface.

[0098] In some embodiments, when the object side surface and / or the image side surface of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are aspherical, the aspherical surface satisfies the following relational expression:

[0099]

[0100] Where Z is the distance from a corresponding point on the aspherical surface to the plane tangent to the vertex of the object side surface or the image side surface, r is the distance from the corresponding point on the aspherical surface to the optical axis, c is the curvature of the vertex (at the optical axis) of the aspherical surface, k is the conic coefficient, and Ai is the i-th order aspherical coefficient of the object side surface or the image side surface.

[0101] Optionally, the optical imaging system 100 further includes a diaphragm 10. Specifically, the diaphragm 10 can be located between the object side of the first lens L1 and the object side surface S8 of the fourth lens L4. More specifically, the diaphragm 10 is located between the first lens L1 and the second lens L2, which is beneficial for expanding the field of view angle of the optical imaging system 100. The diaphragm 10 can be located at any position between the object side of the first lens L1 and the object side surface S8 of the fourth lens L4. The present invention does not make a specific limitation on the position of the diaphragm 10.

[0102] Optionally, the optical imaging system 100 further includes an infrared band-pass filter 30. The infrared band-pass filter 30 is located between the fourth lens L4 and the imaging surface 50. The infrared band-pass filter 30 has a first surface 31 and a second surface 32. The infrared band-pass filter 30 is made of glass, which can increase the transmittance of light in the infrared band, enabling the optical imaging system 100 to be better applied to infrared imaging.

[0103] The term "ghost image" in the present invention, also known as a ghost, refers to an additional image generated near the focal plane of an optical imaging system due to reflection on the lens surface. Its brightness is generally dim, and it is offset from the original image.

[0104] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0105] 0.8 < tan(FOV / 2) < 1.0;

[0106] where FOV is the maximum field of view angle of the optical imaging system 100.

[0107] That is to say, tan(FOV / 2) can be any value between 0.8 and 1.0, for example: 0.81, 0.85, 0.90, 0.95, 0.99, etc.

[0108] When tan(FOV / 2) is less than 0.8, the field of view angle of the optical imaging system 100 is too small to obtain a wide image, and it will also make the effective focal length of the optical imaging system 100 longer, which is not conducive to lens length compression. When 0.8 < tan(FOV / 2) < 1.0, the image range of the optical imaging system 100 can be expanded.

[0109] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0110] FNO ≤ 1.6;

[0111] where FNO is the f-number of the optical imaging system 100.

[0112] That is to say, FNO can be any value less than or equal to 1.6, such as 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, etc.

[0113] When FNO ≤ 1.6, the optical imaging system 100 has a larger light flux and a relatively higher brightness.

[0114] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0115] FNO ≤ 1.3;

[0116] where FNO is the f-number of the optical imaging system 100.

[0117] That is, FNO can be any value less than or equal to 1.3, such as 0.91, 0.95, 1.0, 1.1, 1.2, 1.3, etc.

[0118] When FNO ≤ 1.3, the optical imaging system 100 has a larger light flux and a relatively higher brightness.

[0119] In some embodiments, the optical imaging system 100 satisfies the following conditional expressions:

[0120] 19 < Vd1 < 25;

[0121] 19 < Vd2 < 25;

[0122] 19 < Vd3 < 25;

[0123] 19 < Vd4 < 25;

[0124] Wherein, Vd1 is the Abbe number of the first lens L1, Vd2 is the Abbe number of the second lens L2, Vd3 is the Abbe number of the third lens L3, and Vd4 is the Abbe number of the fourth lens L4.

[0125] That is, Vd1, Vd2, Vd3, and Vd4 can be any values between 19 and 25 respectively, such as 19.1, 20, 21, 22, 23, 24, 24.9, etc.

[0126] When Vd1, Vd2, Vd3, and Vd4 are all greater than 19 and less than 25, it is beneficial for the optical imaging system 100 to obtain a higher modulation transfer function and improve the imaging quality of the optical imaging system 100.

[0127] The term "Modulation Transfer Function" of the present invention is also known as the spatial contrast transfer function and the spatial frequency contrast sensitivity function, which reflects the ability of the optical imaging system 100 to transfer the modulation degrees of various frequency sine objects. The higher the modulation transfer function of the optical imaging system 100, the better the imaging quality.

[0128] In some embodiments, the optical imaging system 100 satisfies the following conditional expressions:

[0129] 0.5 < CT2 / CT3 < 1.5;

[0130] Among them, CT2 is the central thickness of the second lens L2, that is, the distance from the object side surface S3 to the image side surface S4 of the second lens L2 on the optical axis; CT3 is the central thickness of the third lens L3, that is, the distance from the object side surface S5 to the image side surface S6 of the third lens L3 on the optical axis.

[0131] That is to say, CT2 / CT3 can be any value between 0.5 and 1.5, such as 0.51, 0.6, 0.7, 0.8, 0.85, 0.9, 0.95, 1.0, 1.04, 1.2, 1.3, 1.49, etc.

[0132] When 0.5 < CT2 / CT3 < 1.5, the assembly of the optical imaging system 100 can be made more stable.

[0133] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0134] 0 < R5 / R6 < 2.2;

[0135] Among them, R5 is the radius of curvature of the object side surface S3 of the second lens L2 on the optical axis, and R6 is the radius of curvature of the image side surface S4 of the second lens L2 on the optical axis.

[0136] That is to say, R5 / R6 can be any value between 0 and 2.2, such as 0.1, 0.6, 0.8, 1.0, 1.5, 2.0, 2.1, 2.19, etc.

[0137] When 0 < R5 / R6 < 2.2, the shapes of the object side surface S3 and the image side surface S4 of the second lens L2 are similar, the forming is more uniform, and the object side surface S3 and the image side surface S4 are bent on the same side, which is beneficial to improving the resolution of the optical imaging system 100.

[0138] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0139] 0.18 < R7 / R8 < 1.1;

[0140] Among them, R7 is the radius of curvature of the object side surface S5 of the third lens L3 on the optical axis, and R8 is the radius of curvature of the image side surface S6 of the third lens L3 on the optical axis.

[0141] That is to say, R7 / R8 can be any value between 0.18 and 1.1, such as 0.3, 0.5, 0.6, 0.8, 0.9, 1.0, 1.09, etc.

[0142] When 0.18 < R7 / R8 < 1.1, the shapes of the object side surface S5 and the image side surface S6 of the third lens L3 are similar, the forming is more uniform, and the object side surface S5 and the image side surface S6 are bent on the same side, which is beneficial to improving the resolution of the optical imaging system 100.

[0143] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0144] 0.4 < R10 / f < 0.8;

[0145] wherein, R10 is the radius of curvature of the image side surface S8 of the fourth lens L4 with respect to the optical axis, and f is the effective focal length of the optical imaging system 100.

[0146] That is to say, 0.4 < R10 / f < 0.8 can be any value between 0.4 and 0.8, such as 0.41, 0.5, 0.6, 0.7, 0.79, etc.

[0147] When 0.4 < R10 / f < 0.8, the image side surface S8 of the fourth lens L4 is concave near the optical axis and convex at the circumference, which helps to correct the field curvature of the optical imaging system 100, suppress the excessive increase of the principal ray incident angle in the off-axis (away from the optical axis) field of view, and at the same time correct the aberration of the off-axis field of view.

[0148] In some embodiments, the optical imaging system 100 satisfies the following conditional formula:

[0149] -1 < f1 / f23 < 0.5;

[0150] wherein, f1 is the effective focal length of the first lens L1, and f23 is the combined focal length of the second lens L2 and the third lens L3.

[0151] That is to say, f1 / f23 can be any value between -1 and 0.5, such as -0.99, -0.8, -0.5, -0.1, 0.1, 0.2, 0.3, 0.49, etc.

[0152] By providing most of the positive optical power by the first lens L1 and reasonably configuring the optical power of the second lens L2 and the third lens L3, the positive spherical aberration generated by the first lens L1 can be corrected, and a small part of positive optical power can be compensated for the optical imaging system 100, and the optical imaging system 100 has a high imaging quality.

[0153] The optical imaging system 100 of the present invention will be further described in detail below in conjunction with specific embodiments.

[0154] First Embodiment

[0155] Please refer to Figure 1-1 and Figure 1-2 where Figure 1-1 is a schematic structural diagram of the optical imaging system 100 of the first embodiment, Figure 1-2 from left to right are the spherical aberration, astigmatism and distortion curves of the first embodiment of the present invention. From Figure 1-1It can be known that the optical imaging system 100 of this embodiment sequentially includes a first lens L1 with positive optical power, a diaphragm 10, a second lens L2 with positive optical power, a third lens L3 with negative optical power, a fourth lens L4 with positive optical power, an infrared band-pass filter 30, and an imaging surface 50 from the object side to the image side.

[0156] The first lens L1 is made of plastic and has an object side surface S1 and an image side surface S2. The object side surface S1 is convex near the optical axis and concave at the circumference. The image side surface S2 is concave near the optical axis and convex at the circumference.

[0157] The second lens L2 is made of plastic and has an object side surface S3 and an image side surface S4. The object side surface S3 is concave both near the optical axis and at the circumference. The image side surface S4 is convex both near the optical axis and at the circumference.

[0158] The third lens L3 is made of plastic and has an object side surface S5 and an image side surface S6. The object side surface S5 is concave both near the optical axis and at the circumference. The image side surface S6 is convex both near the optical axis and at the circumference.

[0159] The fourth lens L4 is made of plastic and has an object side surface S7 and an image side surface S8. The object side surface S7 is convex both near the optical axis and at the circumference. The image side surface S8 is concave near the optical axis and convex at the circumference.

[0160] In this embodiment, TTL = 2.63 mm; FOV = 86.68°, tan(FOV / 2) = 0.944; FNO = 1.2; CT2 = 0.314, CT3 = 0.215; CT2 / CT3 = 1.460; R5 = -1.808, R6 = -0.849, R5 / R6 = 2.130; R7 = -0.677, R8 = -3.857, R7 / R8 = 0.176; R10 = 0.813, f = 1.691, R10 / f = 0.481; f1 = 2.61, f23 = -3.21, f1 / f23 = -0.813.

[0161] In this embodiment, the optical imaging system 100 satisfies the conditions in Table 1 and Table 2 below.

[0162]

[0163]

[0164] Table 2 shows the aspheric data of the first embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspheric coefficients of each surface.

[0165] From Figure 1-1 and Figure 1-2 It can be known that the optical imaging system 100 of the present invention has high imaging quality while meeting the miniaturization requirement.

[0166] Second Embodiment

[0167] Please refer to Figure 2-1 and Figure 2-2 , where Figure 2-1 is a schematic structural diagram of the optical imaging system 100 of the second embodiment, Figure 2-2 from left to right are the spherical aberration, astigmatism, and distortion curves of the second embodiment of the present invention. As can be seen from Figure 2-1 , the optical imaging system 100 of this embodiment sequentially includes a first lens L1 with a positive optical power, a diaphragm 10, a second lens L2 with a negative optical power, a third lens L3 with a negative optical power, a fourth lens L4 with a positive optical power, an infrared band-pass filter 30, and an imaging surface 50 from the object side to the image side.

[0168] The first lens L1 is made of plastic and has an object side surface S1 and an image side surface S2. Both the near-optical axis and the circumference of the object side surface S1 are convex surfaces. The near-optical axis of the image side surface S2 is a concave surface, and the circumference is a convex surface.

[0169] The second lens L2 is made of plastic and has an object side surface S3 and an image side surface S4. The near-optical axis of the object side surface S3 is a convex surface, and the circumference is a concave surface. The near-optical axis of the image side surface S4 is a concave surface, and the circumference is a convex surface.

[0170] The third lens L3 is made of plastic and has an object side surface S5 and an image side surface S6. Both the near-optical axis and the circumference of the object side surface S5 are concave surfaces. Both the near-optical axis and the circumference of the image side surface S6 are convex surfaces.

[0171] The fourth lens L4 is made of plastic and has an object side surface S7 and an image side surface S8. The near-optical axis of the object side surface S7 is a convex surface, and the circumference is a concave surface. The near-optical axis of the image side surface S8 is a concave surface, and the circumference is a convex surface.

[0172] In this embodiment, TTL = 2.63 mm; FOV = 82.7°, tan(FOV / 2) = 0.880; FNO = 1.40; CT2 = 0.2, CT3 = 0.315; CT2 / CT3 = 0.635; R5 = 7.766, R6 = 6.85, R5 / R6 = 1.134; R7 = -0.998, R8 = -1.78, R7 / R8 = 0.561; R10 = 0.748, f = 1.81, R10 / f = 0.413; f1 = 2.46, f23 = -4.22, f1 / f23 = -0.583.

[0173] In this embodiment, the optical imaging system 100 satisfies the conditions in Table 3 and Table 4 below.

[0174]

[0175]

[0176] Table 4 shows the aspheric data of the second embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspheric coefficients of each surface.

[0177] From Figure 2-1 and Figure 2-2 it can be seen that under the condition of meeting miniaturization, the optical imaging system 100 of the present invention has high imaging quality.

[0178] Third Embodiment

[0179] Please refer to Figure 3-1 and Figure 3-2 , where Figure 3-1 is a schematic structural diagram of the optical imaging system 100 of the third embodiment. Figure 3-2 From left to right are the spherical aberration, astigmatism, and distortion curves of the third embodiment of the present invention. From Figure 3-1 it can be seen that the optical imaging system 100 of this embodiment sequentially includes a first lens L1 with positive optical power, a diaphragm 10, a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, an infrared band - pass filter 30, and an imaging surface 50 from the object side to the image side.

[0180] The first lens L1 is made of plastic and has an object side S1 and an image side S2. Both the near - optical - axis part and the circumferential part of the object side S1 are convex surfaces. The near - optical - axis part of the image side S2 is a concave surface, and the circumferential part is a convex surface.

[0181] The second lens L2 is made of plastic and has an object side S3 and an image side S4. Both the near - optical - axis part and the circumferential part of the object side S3 are concave surfaces. Both the near - optical - axis part and the circumferential part of the image side S4 are convex surfaces.

[0182] The third lens L3 is made of plastic and has an object side S5 and an image side S6. Both the near - optical - axis part and the circumferential part of the object side S5 are concave surfaces. Both the near - optical - axis part and the circumferential part of the image side S6 are convex surfaces.

[0183] The fourth lens L4 is made of plastic and has an object side S7 and an image side S8. The near - optical - axis part of the object side S7 is a convex surface, and the circumferential part is a concave surface. The near - optical - axis part of the image side S8 is a concave surface, and the circumferential part is a convex surface.

[0184] In this embodiment, TTL = 2.644 mm; FOV = 85°, tan(FOV / 2) = 0.916; FNO = 1.60; CT2 = 0.2, CT3 = 0.339; CT2 / CT3 = 0.590; R5 = -9.032, R6 = -7.493, R5 / R6 = 1.205; R7 = -0.954, R8 = -1.067, R7 / R8 = 0.894; R10 = 0.747, f = 1.797, R10 / f = 0.416; f1 = 2.49, f23 = 42.755, f1 / f23 = 0.058.

[0185] In this embodiment, the optical imaging system 100 satisfies the conditions in Table 5 and Table 6 below.

[0186]

[0187]

[0188] Table 6 shows the aspheric data of the third embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspheric coefficients of each surface.

[0189] From Figure 3-1 and Figure 3-2 it can be seen that the optical imaging system 100 of the present invention has high imaging quality while meeting the miniaturization requirements.

[0190] Fourth Embodiment

[0191] Please refer to Figure 4-1 and Figure 4-2 , where Figure 4-1 is a schematic structural diagram of the optical imaging system 100 of the fourth embodiment. Figure 4-2 From left to right are the spherical aberration, astigmatism, and distortion curves of the optical imaging system 100 of the fourth embodiment of the present invention. From Figure 4-1 it can be seen that the optical imaging system 100 of this embodiment sequentially includes a first lens L1 with positive optical power, a diaphragm 10, a second lens L2 with positive optical power, a third lens L3 with negative optical power, a fourth lens L4 with positive optical power, an infrared band - pass filter 30, and an imaging surface 50 from the object side to the image side.

[0192] The first lens L1 is made of plastic and has an object side surface S1 and an image side surface S2. The object side surface S1 is convex both near the optical axis and at the circumference. The image side surface S2 is concave near the optical axis and convex at the circumference.

[0193] The second lens L2 is made of plastic and has an object side surface S3 and an image side surface S4. The object side surface S3 is concave both near the optical axis and at the circumference. The image side surface S4 is convex both near the optical axis and at the circumference.

[0194] The third lens L3 is made of plastic and has an object side S5 and an image side S6. Both the near optical axis and the circumference of the object side S5 are concave surfaces. The near optical axis of the image side S6 is a convex surface, and the circumference is a concave surface.

[0195] The fourth lens L4 is made of plastic and has an object side S7 and an image side S8. The near optical axis of the object side S7 is a convex surface, and the circumference is a concave surface. The near optical axis of the image side S8 is a concave surface, and the circumference is a convex surface.

[0196] In this embodiment, TTL = 2.63 mm; FOV = 87.1°, tan(FOV / 2) = 0.951; FNO = 1.08; CT2 = 0.228, CT3 = 0.245; CT2 / CT3 = 0.931; R5 = -1.826, R6 = -0.942, R5 / R6 = 1.938; R7 = -0.878, R8 = -4.688, R7 / R8 = 0.187; R10 = 1.241, f = 1.689, R10 / f = 0.735; f1 = 2.64, f23 = -4.41, f1 / f23 = -0.599.

[0197] In this embodiment, the optical imaging system 100 meets the conditions in Table 7 and Table 8 below.

[0198]

[0199]

[0200]

[0201] Table 8 shows the aspherical data of the fourth embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspherical coefficients of each surface.

[0202] From Figure 4-1 and Figure 4-2 it can be seen that the optical imaging system 100 of the present invention has high imaging quality while meeting the requirement of miniaturization.

[0203] Fifth Embodiment

[0204] Please refer to Figure 5-1 and Figure 5-2 , where Figure 5-1 is a schematic structural diagram of the optical imaging system 100 of the fifth embodiment. Figure 5-2 From left to right are the spherical aberration, astigmatism, and distortion curves of the fifth embodiment of the present invention. From Figure 5-1It can be known that the optical imaging system 100 of this embodiment sequentially includes, from the object side to the image side, a first lens L1 with positive optical power, a diaphragm 10, a second lens L2 with negative optical power, a third lens L3 with positive optical power, a fourth lens L4 with positive optical power, an infrared band-pass filter 30, and an imaging surface 50.

[0205] The first lens L1 is made of plastic and has an object side surface S1 and an image side surface S2. Both the near-optical axis part and the circumferential part of the object side surface S1 are convex surfaces. The near-optical axis part of the image side surface S2 is a concave surface, and the circumferential part is a convex surface.

[0206] The second lens L2 is made of plastic and has an object side surface S3 and an image side surface S4. Both the near-optical axis part and the circumferential part of the object side surface S3 are concave surfaces. Both the near-optical axis part and the circumferential part of the image side surface S4 are convex surfaces.

[0207] The third lens L3 is made of plastic and has an object side surface S5 and an image side surface S6. Both the near-optical axis part and the circumferential part of the object side surface S5 are concave surfaces. The near-optical axis part of the image side surface S6 is a convex surface, and the circumferential part is a concave surface.

[0208] The fourth lens L4 is made of plastic and has an object side surface S7 and an image side surface S8. The near-optical axis part of the object side surface S7 is a convex surface, and the circumferential part is a concave surface. The near-optical axis part of the image side surface S8 is a concave surface, and the circumferential part is a convex surface.

[0209] In this embodiment, TTL = 2.63 mm; FOV = 86.36°, tan(FOV / 2) = 0.938; FNO = 1.16; CT2 = 0.209, CT3 = 0.294; CT2 / CT3 = 0.711; R5 = -3.523, R6 = -3.707, R5 / R6 = 0.950; R7 = -1.162, R8 = -1.226, R7 / R8 = 0.948; R10 = 0.796, f = 1.7, R10 / f = 0.468; f1 = 2.62, f23 = 55.9, f1 / f23 = 0.047.

[0210] In this embodiment, the optical imaging system 100 satisfies the conditions in Table 9 and Table 10 below.

[0211]

[0212]

[0213]

[0214] Table 10 is the aspheric data of the fifth embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspheric coefficients of each surface.

[0215] From Figure 5-2It can be seen that the optical imaging system 100 of the present invention has a high resolution while meeting the requirement of miniaturization.

[0216] Sixth Embodiment

[0217] Please refer to Figure 6-1 and Figure 6-2 , where Figure 6-1 is a schematic structural diagram of the optical imaging system 100 of the sixth embodiment. Figure 6-2 From left to right are the spherical aberration, astigmatism, and distortion curves of the fifth embodiment of the present invention. It can be seen from Figure 6-1 that the optical imaging system 100 of this embodiment sequentially includes a first lens L1 with a positive optical power, a diaphragm 10, a second lens L2 with a positive optical power, a third lens L3 with a positive optical power, a fourth lens L4 with a negative optical power, an infrared band-pass filter 30, and an imaging surface 50 from the object side to the image side.

[0218] The first lens L1 is made of plastic and has an object side surface S1 and an image side surface S2. Both the near-optical axis and the circumferential part of the object side surface S1 are convex surfaces. The near-optical axis part of the image side surface S2 is a concave surface, and the circumferential part is a convex surface.

[0219] The second lens L2 is made of plastic and has an object side surface S3 and an image side surface S4. The near-optical axis part of the object side surface S3 is a convex surface, and the circumferential part is a concave surface. The near-optical axis part of the image side surface S4 is a concave surface, and the circumferential part is a convex surface.

[0220] The third lens L3 is made of plastic and has an object side surface S5 and an image side surface S6. Both the near-optical axis and the circumferential part of the object side surface S5 are concave surfaces. The near-optical axis part of the image side surface S6 is a convex surface, and the circumferential part is a concave surface.

[0221] The fourth lens L4 is made of plastic and has an object side surface S7 and an image side surface S8. The near-optical axis part of the object side surface S7 is a convex surface, and the circumferential part is a concave surface. The near-optical axis part of the image side surface S8 is a concave surface, and the circumferential part is a convex surface.

[0222] In this embodiment, TTL = 2.60 mm; FOV = 78°, tan(FOV / 2) = 0.81; FNO = 1.40; CT2 = 0.21, CT3 = 0.307; CT2 / CT3 = 0.684; R5 = 11.062, R6 = 116.012, R5 / R6 = 0.095; R7 = -0.95, R8 = -0.887, R7 / R8 = 1.071; R10 = 0.785, f = 1.831, R10 / f = 0.429; f1 = 2.5, f23 = 5.727, f1 / f23 = 0.437.

[0223] In this embodiment, the optical imaging system 100 meets the conditions in Table 11 and Table 12 below.

[0224]

[0225]

[0226] Table 12 shows the aspheric data of the sixth embodiment, where k is the conic coefficient of each surface, and A4 - A20 are the 4th - 20th order aspheric coefficients of each surface.

[0227] From Figure 6-1 and Figure 6-2 it can be seen that the optical imaging system 100 of the present invention has high imaging quality while meeting the requirement of miniaturization.

[0228] Please refer to Figure 7 , the present invention further provides an imaging device 200, which includes the optical imaging system 100 of the present invention and a photosensitive element 210. The photosensitive element 210 is located on the image side of the optical imaging system 100.

[0229] The photosensitive element 210 of the present invention can be a Charge Coupled Device (CCD) or a Complementary Metal - Oxide Semiconductor Sensor (CMOS sensor).

[0230] The imaging device 200 of the present invention has a wide focusing range and imaging quality while ensuring miniaturization.

[0231] For other feature descriptions of the imaging device 200, please refer to the above description and will not be elaborated here.

[0232] Please refer to Figure 8 , the present invention further provides an electronic device 300, which includes a device main body 310 and the imaging device 200 of the present invention. The imaging device 200 is installed on the device main body 310.

[0233] The electronic device 300 of the present invention includes, but is not limited to, vehicle-mounted cameras, computers, laptops, tablets, mobile phones, cameras, smart bracelets, smart watches, smart glasses, e-book readers, portable multimedia players, mobile medical devices, etc.

[0234] The camera of the electronic device 300 of the present invention has a small thickness, which is beneficial to reducing the volume of the electronic device 300.

[0235] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An optical imaging system, characterized in that, There are a total of four lenses with refractive power, which successively include from the object side to the image side: A first lens with positive optical power, where the object side surface of the first lens is convex near the optical axis; the image side surface is concave near the optical axis; A second lens with optical power; A third lens with optical power, where the object side surface of the third lens is concave near the optical axis; the image side surface is convex near the optical axis; and A fourth lens with optical power, where the object side surface of the fourth lens is convex near the optical axis; the image side surface is concave near the optical axis; Among them, the optical imaging system satisfies the following conditional expressions: TTL ≤ 2.644 mm; 0.8 < tan(FOV / 2) < 1.0; FNO ≤ 1.6; Among them, TTL is the distance from the object side surface of the first lens to the imaging surface on the optical axis, FOV is the maximum field of view angle of the optical imaging system, and FNO is the aperture number of the optical imaging system.

2. The optical imaging system according to claim 1, wherein At least one inflection point is provided on at least one of the object side surface and the image side surface of the fourth lens.

3. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 1.08 ≤ FNO ≤ 1.4; Among them, FNO is the aperture number of the optical imaging system.

4. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 1.08 ≤ FNO ≤ 1.3; Among them, FNO is the aperture number of the optical imaging system.

5. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 19 < Vd1 < 25; 19 < Vd2 < 25; 19 < Vd3 < 25; 19 < Vd4 < 25; Among them, Vd1 is the Abbe number of the first lens, Vd2 is the Abbe number of the second lens, Vd3 is the Abbe number of the third lens, and Vd4 is the Abbe number of the fourth lens.

6. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 0.5 < CT2 / CT3 < 1.5; Among them, CT2 is the central thickness of the second lens, and CT3 is the central thickness of the third lens.

7. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 0 < R5 / R6 < 2.2; Among them, R5 is the radius of curvature of the object side surface of the second lens on the optical axis, and R6 is the radius of curvature of the image side surface of the second lens on the optical axis.

8. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 0.18 < R7 / R8 < 1.1; Among them, R7 is the radius of curvature of the object side surface of the third lens on the optical axis, and R8 is the radius of curvature of the image side surface of the third lens on the optical axis.

9. The optical imaging system according to claim 1, wherein The optical imaging system satisfies the following conditional expressions: 0.4 < R10 / f < 0.8; Among them, R10 is the radius of curvature of the image side surface of the fourth lens on the optical axis, and f is the effective focal length of the optical imaging system.

10. The optical imaging system according to any one of claims 1-9, characterized in that, The optical imaging system satisfies the following conditional expressions: -1 < f1 / f23 < 0.5; Among them, f1 is the effective focal length of the first lens, and f23 is the combined focal length of the second lens and the third lens.

11. An imaging device, characterized in that, Including: The optical imaging system according to any one of claims 1-10; And An image sensor, which is located on the image side of the optical imaging system.

12. An electronic device, characterized in that, Including: A device body; And The imaging device according to claim 11, which is installed on the device body.

Images