Video conference lens and electronic equipment

Abstract

The utility model discloses a video conference lens and an electronic device. The lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens from an object side to an image side, the first lens has negative diopter, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; the second lens has positive diopter, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; the third lens has positive diopter, the object side surface of the lens is a convex surface, and the image side surface of the lens is a convex surface; the fourth lens has negative diopter, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; the fifth lens has negative diopter, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface. According to the video conference lens, the compact structure is kept, meanwhile, performance improvement in multiple aspects such as high resolution, low distortion and large target surface compatibility is achieved, and an ideal optical solution is provided for a video conference system.

Description

TECHNICAL FIELD

[0001] The utility model relates to video conference lens technical field especially, a kind of video conference lens and electronic equipment. BACKGROUND

[0002] With the continuous progress of video conference system technology, the performance requirements of lens are increasingly stringent. Modern video conference lens not only needs to match with large target surface imaging element to meet the needs of high resolution and large field of view, but also must realize miniaturization design while maintaining excellent imaging quality. However, the design of existing video conference lens often faces technical bottleneck: in the process of pursuing miniaturization, it is difficult to balance large target surface and imaging quality. This contradiction puts forward higher challenge to the design of optical system, requires breakthrough in power distribution, aberration correction and structure optimization, etc. to meet the needs of modern video conference system for high-performance, miniaturization lens. SUMMARY

[0003] Therefore, the purpose of the utility model is to provide a kind of video conference lens and electronic equipment. The lens can at least solve one of the technical defects mentioned in the background art.

[0004] According to one aspect of the utility model, a kind of video conference lens is provided, the lens is sequentially first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens from object side to image side;

[0005] The first lens has negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave;

[0006] The second lens has positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave;

[0007] The third lens has positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is convex;

[0008] The fourth lens has negative refractive power, the object side surface of the lens is concave, and the image side surface of the lens is concave;

[0009] The fifth lens has negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave;

[0010] The sixth lens has positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave;

[0011] The seventh lens has positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave;

[0012] The eighth lens has negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave.

[0013] In the above technical solution, through the optimization design of the above technical solution, the video conference lens realizes the performance improvement of high resolution, low distortion, large target surface compatibility and the like while maintaining the compact structure, and provides an ideal optical solution for the video conference system. Specifically, by reasonably configuring the diopter and surface curvature of the lens group, the total length of the system (TTL≤25mm) is effectively optimized, the manufacturing cost is significantly reduced, and excellent optical performance is maintained under the compact structure. The symmetric structure design of the front group of four pieces and the rear group of four pieces significantly improves the imaging quality of the system, while effectively reducing the system distortion (F-Tan(Theta) distortion <8%, TV distortion <5%), ensuring that the imaging picture has no obvious distortion influence, and meeting the needs of high-quality video conference. The design of the rear group of lenses continuously bending towards the image surface direction significantly reduces the field curvature of the system, while optimizing the lens outer diameter size (lens effective diameter <φ12.6mm), realizing the compact design of the system under the premise of maintaining a large image surface (target surface height >10.24mm, matching 1 / 1.56” sensor). The optical transfer function (MTF) of the system full field of view is greater than 0.4 at 125lp / mm frequency, indicating that the lens has excellent imaging performance under high resolution conditions and can provide clear and sharp image output. The lens performs well in volume, image quality, distortion control and large target surface compatibility, and is suitable for the demand of modern video conference equipment for small-sized and high-performance optical lens.

[0014] In some embodiments, the fifth lens and the sixth lens are cemented as a double-cemented lens.

[0015] In the technical solution, the fifth lens and the sixth lens are designed as a doublet lens, and the image side surface of the sixth lens is designed as a concave surface. The technical solution has obvious advantages in suppressing aberration, improving imaging quality, and optimizing the light convergence path, and provides an efficient optical solution for the video conference lens. Specifically, the doublet lens is formed by bonding two lenses made of different optical materials, and the chromatic aberration is effectively eliminated by compensating for the dispersion characteristics of the two lenses. At the same time, the spherical aberration, field curvature, and astigmatism are significantly reduced. This design makes the light rays in different fields of view converge more uniformly on the imaging surface, thereby improving the overall imaging quality. The image side surface of the sixth lens is designed as a concave surface, which helps to optimize the deflection path of the light, so that the incident light beams of each field of view can converge more accurately on the imaging surface after passing through the optical system. This design not only improves the clarity of the image, but also enhances the optical transfer function (MTF) performance of the system, ensuring excellent imaging quality under high resolution conditions. The design of the doublet lens provides sufficient degrees of freedom to balance and correct various aberrations while maintaining the compactness of the optical system. This structural optimization optimizes the power distribution of the system, enabling higher performance in a limited physical size.

[0016] In some embodiments, the lens satisfies the following conditional expression:

[0017] nd7>2.0

[0018] In the formula, nd7 is the refractive index of the seventh lens.

[0019] In the technical solution, the use of high refractive index material lenses can significantly reduce the spacing between the lenses, thereby effectively shortening the overall length of the optical system. Specifically, high refractive index material (the refractive index of the seventh lens satisfies nd7>2.0) can enhance the refractive ability of light, allowing the lenses to achieve the same power distribution in a shorter spacing. This design reduces the air gap between the lenses, thereby optimizing the overall layout of the optical system.

[0020] In some embodiments, the lens satisfies the following conditional expression:

[0021] |nd2-nd3|>0.25; |vd3-vd2|>30

[0022] In the formula, nd2 and nd3 are the refractive indices of the second lens and the third lens, respectively, and vd2 and vd3 are the dispersion coefficients of the second lens and the third lens, respectively.

[0023] In the technical solution, the material parameters of the second lens and the third lens are reasonably selected to effectively correct the chromatic aberration of the optical system and significantly improve the imaging quality. Specifically, by setting the refractive index difference and the dispersion coefficient difference of the second lens and the third lens, the combination of the positive focal length lens made of high dispersion coefficient material and the negative focal length lens made of low dispersion coefficient material effectively compensates the chromatic aberration of the optical system. This design significantly reduces the axial chromatic aberration and lateral chromatic aberration by compensating each other through the dispersion characteristics of the materials, ensuring that the imaging system has excellent color restoration ability in the full field of view. The conditional design not only optimizes the chromatic aberration performance of the system, but also further improves the MTF (optical transfer function) performance of the system by reasonably allocating the focal length, ensuring clear and sharp image output under high resolution conditions. At the same time, this material combination design provides greater design freedom for the overall optimization of the optical system, which helps to achieve higher optical performance in limited physical size.

[0024] In some embodiments, a diaphragm is arranged between the fourth lens and the fifth lens.

[0025] In the technical solution, a diaphragm is arranged between the fourth lens and the fifth lens to effectively correct the aberration of the optical system and significantly improve the imaging quality. Specifically, by adjusting the distance between the diaphragm and the lens group, the focusing characteristics of the light in the optical system are optimized. This design is particularly helpful in compensating for the coma, i.e. the focusing difference of light at the edge and center of the lens, thereby improving the imaging sharpness of the system. At the same time, the position optimization of the diaphragm also helps to reduce the distortion of the system, ensuring that the geometric shape of the imaging picture remains true.

[0026] In some embodiments, the lens satisfies the following conditional expression:

[0027] 3 < TTL / f < 4

[0028] In the formula, TTL is the total optical length of the lens, and f is the focal length of the lens.

[0029] In the above technical solution, by reasonably controlling the ratio of the total optical length (TTL) to the focal length (f), the best balance between the volume and the imaging quality of the optical system is ensured. Specifically, when the ratio of the total optical length to the focal length satisfies 3 < TTL / f < 4, the optical system can ensure excellent imaging quality while maintaining a small volume. This design precisely controls the compactness of the optical system, avoiding the decline in imaging quality caused by too small volume and the unsatisfactory miniaturization caused by too large volume. When TTL / f < 3, the volume of the optical system may be too small, which limits the light path and affects the imaging quality. When 3 < TTL / f < 4, the optical system can achieve optimal power distribution and aberration correction within a limited volume, ensuring that the imaging quality is not affected. When TTL / f > 4, the volume of the optical system may be too large, increasing the manufacturing cost and portability problems, and possibly leading to redundancy of optical performance.

[0030] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are glass spherical lenses, and the eighth lens is a glass aspherical lens.

[0031] In the above technical solution, the processing technology of spherical lenses is mature, and the manufacturing cost is relatively low. Compared with aspherical lenses, the processing equipment and technology of spherical lenses are simpler, suitable for large-scale production, and the material uniformity is high, which can maintain stable optical performance in various environments, suitable for optical systems that need to work stably for a long time. In addition, the eighth lens adopts a glass aspherical design, which significantly improves the utilization efficiency of single-piece lenses by increasing the order of even aspheric surfaces. This design not only reduces the total number of lenses required, but also effectively reduces the overall volume of the lens, while significantly suppressing edge distortion and improving the imaging quality of the system. Specifically, the aspherical design optimizes the focusing characteristics of the light by precisely controlling the curvature variation of the lens surface, so that a single-piece lens can bear more power distribution. This design reduces the need for additional lenses, thereby simplifying the structure of the optical system.

[0032] According to another aspect of the present application, an electronic device is provided, according to the video conference lens described above; and an image sensor configured to receive an image formed by the video conference lens.

[0033] In the above technical solution, the advantages of the electronic device depend on the video conference lens, which will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0035] Figure 1 is a structural schematic diagram of a video conference lens example 1 of the present application;

[0036] Figure 2 is an MTF curve diagram of the video conference lens example 1 of the present application;

[0037] Figure 3 is a Through Focus curve diagram of the video conference lens example 1 of the present application;

[0038] Figure 4 is a Lateral Color curve diagram of the video conference lens example 1 of the present application;

[0039] Figure 5 is a field curvature & distortion curve diagram of the video conference lens example 1 of the present application;

[0040] Figure 6 is a structural schematic diagram of a video conference lens example 2 of the present application;

[0041] Figure 7 is an MTF curve diagram of the video conference lens example 2 of the present application;

[0042] Figure 8 is a Through Focus curve diagram of the video conference lens example 2 of the present application;

[0043] Figure 9 is a Lateral Color curve diagram of the video conference lens example 2 of the present application;

[0044] Figure 10 is a field curvature & distortion curve diagram of the video conference lens example 2 of the present application;

[0045] Figure 11 is a structural schematic diagram of a video conference lens example 3 of the present application;

[0046] Figure 12 is an MTF curve diagram of the video conference lens example 3 of the present application;

[0047] Figure 13is a Through Focus curve diagram of the video conference lens example 3 of the utility model;

[0048] Figure 14 is a Lateral Color curve diagram of the video conference lens example 3 of the utility model;

[0049] Figure 15 is a field curvature & distortion curve diagram of the video conference lens example 3 of the utility model;

[0050] Figure 16 is a structure schematic diagram of the video conference lens example 4 of the utility model;

[0051] Figure 17 is an MTF curve diagram of the video conference lens example 4 of the utility model;

[0052] Figure 18 is a Through Focus curve diagram of the video conference lens example 4 of the utility model;

[0053] Figure 19 is a Lateral Color curve diagram of the video conference lens example 4 of the utility model;

[0054] Figure 20 is a field curvature & distortion curve diagram of the video conference lens example 4 of the utility model;

[0055] Figure 21 is a structure schematic diagram of the video conference lens example 5 of the utility model;

[0056] Figure 22 is an MTF curve diagram of the video conference lens example 5 of the utility model;

[0057] Figure 23 is a Through Focus curve diagram of the video conference lens example 5 of the utility model;

[0058] Figure 24 is a Lateral Color curve diagram of the video conference lens example 5 of the utility model;

[0059] Figure 25 is a field curvature & distortion curve diagram of the video conference lens example 5 of the utility model;

[0060] Figure 26 is a structure schematic diagram of the electronic equipment example 6 of the utility model; DETAILED DESCRIPTION

[0061] The utility model will be described in further detail below in connection with the drawings and examples. It is particularly pointed out that the following examples are only for illustrating the utility model, but do not limit the scope of the utility model. Similarly, the following examples are only part of the embodiments of the utility model rather than all the embodiments, and all other embodiments obtained by the ordinary skilled in the art without making creative efforts belong to the scope of the utility model protection.

[0062] The utility model discloses a video conference lens with high optical performance and electronic equipment. The embodiment according to the utility model will be described in detail with reference to the drawings.

[0063] Figure 1 、 Figure 6 、 Figure 11 、 Figure 16 、 Figure 21 is the section view of the glass-plastic day and night confocal lens (optical system) according to examples 1 to 5. The glass-plastic day and night confocal lens according to example 1 is used for the optical equipment of camera equipment and interchangeable lens including such as digital video camera, digital still camera, broadcast camera, monitoring camera and the like. In each section view, the left side is the object side OBJ and the right side is the image side IMA, and the optical axis OA. In each section view, Li indicates the i-th lens, L56 indicates the cemented lens group, and G2 indicates the protection glass & filter. IMA indicates the image plane, and when the glass-plastic day and night confocal lens according to examples 1 to 5 is used for the camera optical system of digital video camera or digital still camera, the solid-state camera element (photoelectric conversion element) such as CMOS image sensor or CCD image sensor is arranged on the camera plane IMA.

[0064] According to the video conference lens of various examples, in order from the object side to the image side, the video conference lens comprises: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8; the first lens L1 has a negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave; the second lens L2 has a positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave; the third lens L3 has a positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is convex; the fourth lens L4 has a negative refractive power, the object side surface of the lens is concave, and the image side surface of the lens is concave; the fifth lens L5 has a negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave; the sixth lens L6 has a positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave; the seventh lens L7 has a positive refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave; and the eighth lens L8 has a negative refractive power, the object side surface of the lens is convex, and the image side surface of the lens is concave. The fifth lens L5 and the sixth lens L6 are cemented into a double-cemented lens L56. A diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are glass spherical lenses, and the eighth lens L8 is a glass aspherical lens.

[0065] The video conference lens according to various examples can satisfy at least one of the following setting conditions 1) to 10):

[0066] 1) the first lens, 1.55 < nd < 1.65, 55 < vd < 65;

[0067] 2) the second lens, 1.80 < nd < 2.05, 20 < vd < 40;

[0068] 3) the third lens, 1.56 < nd < 1.62, 63 < vd < 72;

[0069] 4) the fourth lens, 1.55 < nd < 1.65, 30 < vd < 40;

[0070] 5) the fifth lens, 1.75 < nd < 1.85, 22 < vd < 27;

[0071] 6) the sixth lens, 1.56 < nd < 1.63, 63 < vd < 72;

[0072] 7) the seventh lens, 2.00 < nd < 2.10, 25 < vd < 30;

[0073] 8) the eighth lens, 1.75 < nd < 1.85, 35 < vd < 50;

[0074] 9) |nd2-nd3| > 0.25; |vd3-vd2| > 30;

[0075] 10) 3 < TTL / f < 4;

[0076] In the above conditional expressions, nd is the refractive index, and vd is the dispersion coefficient; nd2 and nd3 are the refractive indices of the second lens and the third lens respectively, and vd2 and vd3 are the dispersion coefficients of the second lens and the third lens respectively; TTL is the total optical length of the lens, and f is the focal length of the lens.

[0077] Now, detailed descriptions of the video conference lens according to various examples will be given.

[0078] The optical structure of Example 1 is shown in Table 1 and Table 2. Figure 1 The specific parameters of Example 1 are shown in Table 1 and Table 2. In Example 1, the focal length f of the lens is 6.4 mm, and the TTL is 24.9 mm.

[0079] Table 1 shows the parameter table of Example 1.

[0080]

[0081] Table 2 shows the aspherical surface parameter table.

[0082] Surface K A4 A6 A8 A10 A12 10 -4.104E-03 -2.377E-04 2.224E-05 4.777E-07 -3.076E-08 13 -3.258E-03 -4.233E-04 6.217E-05 -3.440E-06 9.156E-08

[0083] Figure 2 The MTF curve of Example 1 is shown in Table 1 and Table 2. The MTF of the field of view of 0-0.8 is greater than 0.5 at 125 lp / mm, and the MTF of the full field of view is greater than 0.4 at 125 lp / mm. Figure 3 The Through Focus curve of Example 1 is shown in Table 1 and Table 2. The full field of view curve is concentrated, and the defocus amount is small. Figure 4 The Lateral Color curve of Example 1 is shown in Table 1 and Table 2. The lens magnification chromatic aberration correction is less than 3 um. Figure 5 The Field Curvature & Distortion curve of Example 1 is shown in Table 1 and Table 2. The field curvature curves of each wavelength coincide, and the lens chromatic aberration correction is good; the distortion is less than 8%, the TV distortion is less than 5%, and the imaging picture will not be affected by the too large distortion.

[0084] The optical structure of Example 2 is shown in Table 3 and Table 4. Figure 6 The specific parameters of Example 2 are shown in Table 3 and Table 4. In Example 2, the focal length f of the lens is 6.4 mm, and the TTL is 25 mm.

[0085] Table 3 shows the parameter table of Example 2.

[0086]

[0087] Table 4 shows the aspherical surface parameter table.

[0088] Surface K A4 A6 A8 A10 A12 10 2.25 -4.547E-03 -1.233E-04 1.739E-05 -2.669E-07 2.777E-09 13 1.60 -3.485E-03 -2.540E-04 3.745E-05 -2.302E-06 5.959E-08

[0089] Figure 7 For the MTF curve of Example 1, the MTF of 0-0.8 field is greater than 0.5 at 125 lp / mm, and the MTF of full field is greater than 0.4 at 125 lp / mm. Figure 8 For the Through Focus curve of Example 1, the curves of full field are concentrated, and the defocus amount is small. Figure 9 For the Lateral Color curve of Example 1, the chromatic aberration correction of the lens is less than 3 um. Figure 10 For the Field Curvature & Distortion curve of Example 1, the field curvature curves of different wavelengths coincide, the chromatic aberration correction of the lens is good, the distortion is less than 8%, the TV distortion is less than 5%, and the imaging picture will not be affected by too large distortion.

[0090] The optical structure of Example 3 is shown in Table 5, Table 6. Figure 11 The specific parameters of Example 3 are shown in Table 5, Table 6. In Example 3, the focal length of the lens f = 6.4 mm, and the TTL = 24.9 mm.

[0091] Table 5 shows the parameter table of Example 3.

[0092]

[0093] Table 6 shows the aspherical surface parameter table.

[0094] Surface K A4 A6 A8 A10 A12 10 0.29 -4.125E-03 -1.347E-04 2.233E-05 -1.117E-06 3.516E-08 13 -0.35 -2.699E-03 -2.574E-04 4.434E-05 -2.867E-06 7.209E-08

[0095] Figure 12 For the MTF curve of Example 3, the MTF of 0-0.8 field is greater than 0.5 at 125 lp / mm, and the MTF of full field is greater than 0.4 at 125 lp / mm. Figure 13 For the Through Focus curve of Example 3, the curves of full field are concentrated, and the defocus amount is small. Figure 14 For the Lateral Color curve of Example 3, the chromatic aberration correction of the lens is less than 3 um. Figure 15 For the Field Curvature & Distortion curve of Example 3, the field curvature curves of different wavelengths coincide, the chromatic aberration correction of the lens is good, the distortion is less than 8%, the TV distortion is less than 5%, and the imaging picture will not be affected by too large distortion.

[0096] The optical structure of Example 4 is shown in Table 7, Table 8. Figure 16 The specific parameters of Example 4 are shown in Table 7, Table 8. In Example 4, the focal length of the lens f = 6.4 mm, and the TTL = 25 mm.

[0097] Table 7 shows the parameter table of Example 4.

[0098]

[0099] Table 8 Aspherical surface parameter table

[0100] Surface K A4 A6 A8 A10 A12 10 0.20 -3.462E-03 -4.372E-05 6.102E-06 1.702E-08 6.082E-09 13 0.02 -2.153E-03 -1.430E-04 2.484E-05 -1.522E-06 4.398E-08

[0101] Figure 2 For the MTF curve diagram of Example 4, the MTF of 0-0.8 field of view is greater than 0.5 at 125 lp / mm, and the MTF of full field of view is greater than 0.4 at 125 lp / mm. Figure 3 For the Through Focus curve diagram of Example 4, the full field of view curve is concentrated, and the defocus amount is small. Figure 4 For the Lateral Color curve diagram of Example 4, the lens magnification chromatic aberration correction is less than 3um. Figure 5 For the Field Curvature & Distortion curve diagram of Example 4, the field curvature curves of each wavelength coincide, the lens chromatic aberration correction is good; the distortion is less than 8%, the TV distortion is less than 5%, and the imaging picture will not be affected by too large distortion.

[0102] The optical structure of Example 5 is shown in Figure 1 The specific parameters of Example 5 are shown in Table 9 and Table 10. In Example 5, the lens focal length f = 6.4mm, and the TTL = 25mm.

[0103] Table 9 Parameter table of Example 5

[0104]

[0105] Table 10 Aspherical surface parameter table

[0106] Surface K A4 A6 A8 A10 A12 10 0.73 -3.543E-03 -5.845E-05 3.847E-06 3.397E-07 -1.594E-09 13 0.07 -1.965E-03 -1.603E-04 2.410E-05 -1.390E-06 3.942E-08

[0107] Figure 2 For the MTF curve diagram of Example 5, the MTF of 0-0.8 field of view is greater than 0.5 at 125 lp / mm, and the MTF of full field of view is greater than 0.4 at 125 lp / mm. Figure 3 For the Through Focus curve diagram of Example 5, the full field of view curve is concentrated, and the defocus amount is small. Figure 4 For the Lateral Color curve diagram of Example 5, the lens magnification chromatic aberration correction is less than 3um. Figure 5 For the Field Curvature & Distortion curve diagram of Example 5, the field curvature curves of each wavelength coincide, the lens chromatic aberration correction is good; the distortion is less than 8%, the TV distortion is less than 5%, and the imaging picture will not be affected by too large distortion.

[0108] Based on Examples 1 to 5, the present application has the following advantages:

[0109] The video conference lens realizes performance improvement in high resolution, low distortion, large target surface compatibility and other aspects while maintaining a compact structure, and provides an ideal optical solution for a video conference system. Specifically, by reasonably configuring the refractive power and surface curvature of the lens group, the technical scheme effectively optimizes the total length of the system (TTL≤25mm), while significantly reducing the manufacturing cost, and ensures that the excellent optical performance is maintained under the compact structure. The symmetric structure design of the front group of four pieces and the rear group of four pieces significantly improves the imaging quality of the system, while effectively reducing the system distortion (F-Tan(Theta) distortion <8%, TV distortion <5%), ensuring that the imaging picture is not significantly affected by distortion, meeting the needs of high-quality video conference. The design of the rear group of continuously used lenses bending towards the image surface direction significantly reduces the field curvature of the system, while optimizing the lens outer diameter size (lens effective diameter <φ12.6mm), realizing the compact design of the system on the premise of maintaining a large image surface (target surface height >10.24mm, matching 1 / 1.56” sensor). At a frequency of 125lp / mm, the optical transfer function (MTF) of the system in the full field of view is greater than 0.4, indicating that the lens has excellent imaging performance under high resolution conditions and can provide clear and sharp image output. The lens performs well in volume, image quality, distortion control and large target surface compatibility, and meets the needs of modern video conference equipment for small-sized and high-performance optical lenses.

[0110] Example 6

[0111] Reference will now be made to Figure 26 A description of the electronic device A according to Example 6 of the present application will be given. Figure 26 is a schematic view of an electronic device (industrial camera) in which the video conference lens according to Examples 1 to 5 is used for an imaging optical system.

[0112] In Figure 26 , reference sign A2 denotes an electronic device main body, and reference sign A1 denotes an imaging optical system (interchangeable lens) including the video conference lens according to Examples 1 to 5. Reference sign A3 denotes an image sensor (photoelectric conversion element) such as a CMOS image sensor or a CCD image sensor, which is built into the camera main body A2 and receives light from the imaging optical system A1 (forms an optical image through the imaging optical system A1 and performs photoelectric conversion.

[0113] By using the video conference lens according to Examples 1 to 5 for an electronic device such as a digital still camera, an electronic device with a high optical performance lens can be obtained.

[0114] While the application has been described with reference to the typical embodiments, it will be understood that the application is not limited to the details of the embodiments disclosed. The application extends to all modifications and equivalent structures and functions falling within the scope of the appended claims taken in their broadest possible interpretation.

Claims

1. A video conference lens characterized by, The lens sequentially comprises, from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; The first lens has a negative refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; The second lens has a positive refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; The third lens has a positive refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a convex surface; The fourth lens has a negative refractive power, the object side surface of the lens is a concave surface, and the image side surface of the lens is a concave surface; The fifth lens has a negative refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; The sixth lens has a positive refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; The seventh lens has a positive refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface; The eighth lens has a negative refractive power, the object side surface of the lens is a convex surface, and the image side surface of the lens is a concave surface.

2. The video conference lens according to claim 1, wherein the fifth lens and the sixth lens are cemented together as a double cemented lens.

3. The video conference lens according to claim 1, wherein the lens satisfies the following condition formula: nd7>2.0 wherein nd7 is the refractive index of the seventh lens.

4. The video conference lens according to claim 1, wherein the lens satisfies the following condition formula: |nd2-nd3|>0.25; |vd3-vd2|>30 wherein nd2 and nd3 are the refractive indices of the second lens and the third lens, respectively, and vd2 and vd3 are the dispersion coefficients of the second lens and the third lens, respectively.

5. The video conference lens according to claim 1, wherein a diaphragm is arranged between the fourth lens and the fifth lens.

6. The video conference lens according to claim 1, wherein the lens satisfies the following condition formula: 3<TTL / f<4 wherein TTL is the total optical length of the lens, and f is the focal length of the lens.

7. The video conference lens according to claim 1, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are glass spherical lenses, and the eighth lens is a glass aspherical lens. A video conference lens according to any one of claims 1-7; and an image sensor configured to receive an image formed by the video conference lens. ​ ​ ​ ​ 8. An electronic device, comprising: ​ ​

Images