Video lens and electronic device

Abstract

This invention discloses a video lens and an electronic device. The video lens has an object side and an image side arranged opposite to each other along the optical axis. The video lens includes a lens barrel and a lens group disposed within the lens barrel. The lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip arranged sequentially from the object side to the image side. The video lens satisfies the following condition: 0.1≤FA / TTL≤0.25, where FA is the optical focal length of the video lens, and TTL is the distance between the object side surface of the first lens and the imaging surface of the video lens on the optical axis. Through the reasonable arrangement of the five lenses, the optical focal length FA and the total optical length TTL of the optical system of the video lens satisfy the relationship: 0.1≤FA / TTL≤0.25, and the distortion rate reaches below 3%, so as to provide a video lens with small size, low distortion rate, and 4K high pixel resolution.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, in particular to a video lens and an electronic device. Background Art

[0002] At present, there are many small video lenses used for video conferencing and webcasting. Now, the requirement for image quality has been further improved; module manufacturers generally need to correct lens distortion, which affects production efficiency, and hope that the lens distortion can be further reduced; at the same time, in order to obtain a larger depth of field or a wider object distance for use, a focus adjustment device is often used in combination. At present, the focus adjustment devices at different prices on the market vary significantly. In order to meet the requirements of high image quality and low cost, this optical system is designed.

[0003] For general video lenses of the same type with a small volume, the image quality is relatively poor, and the distortion reaches 7% - 8%, and distortion correction needs to be done by backend engineering; however, for video lenses with better performance and smaller distortion, the volume is generally larger, and the volume requirement for the corresponding focus adjustment device is enlarged, increasing the overall cost. Summary of the Invention

[0004] The main object of the present invention is to propose a video lens and an electronic device, aiming to provide a video lens with a small volume, a small distortion rate, and capable of achieving 4K high pixels.

[0005] To achieve the above object, a video lens proposed by the present invention has an object side and an image side arranged oppositely along the optical axis direction. The video lens includes a lens barrel and a lens group disposed inside the lens barrel. The lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip arranged in sequence from the object side to the image side. The first lens and the second lens are both meniscus lenses, and the concave surfaces of the first lens and the second lens face the image side. The third lens is a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a biconcave lens, and the sixth lens is a biconvex lens;

[0006] The video lens satisfies the following condition: 0.1 ≤ FA / TTL ≤ 0.25, where FA is the optical focal length of the video lens, and TTL is the distance on the optical axis between the object side surface of the first lens and the imaging surface of the video lens.

[0007] Optionally, the video lens further satisfies the following condition: 1.0 < TTL / Φ1 < 1.8, where Φ1 is the maximum aperture of the video lens.

[0008] Optionally, the video lens further satisfies the following condition: 0.8 < IM / Φ2 < 1.1, where IM is the size of the imaging surface of the video lens, and Φ2 is the thread diameter of the end of the lens barrel at the image side.

[0009] Optionally, Φ2 = 8mm.

[0010] Optionally, the refractive index of the first lens is nd1, and the Abbe number of the first lens is vd1, wherein 1.5≤nd1≤1.9 and 20≤vd1≤60.

[0011] Optionally, the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are made of plastic.

[0012] The third lens is made of glass.

[0013] Optionally, the refractive index of the third lens is nd3, and the Abbe number of the third lens is vd3, wherein 1.84≤nd3≤2.01, and 24≤vd3≤30.

[0014] Optionally, the refractive index of the second lens is nd2, the refractive index of the fifth lens is nd5, the Abbe number of the second lens is vd2, and the Abbe number of the fifth lens is vd5, wherein 1.6≤nd2≤1.7, 1.6≤nd5≤1.7, 18≤vd2≤19, and 18≤vd5≤19.

[0015] The present invention also provides a projection device, the projection device including an electronic device, the electronic device including the above-described video lens.

[0016] Optionally, the electronic device further includes a focusing device located on the image side of the video lens for adjusting the focal length of the video lens.

[0017] The technical solution provided by this invention comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip, arranged sequentially from the object side to the image side. The first and second lenses are both meniscus lenses, with their concave surfaces facing the image side. The third lens is a biconvex lens; the fourth lens is a biconvex lens; the fifth lens is a biconcave lens; and the sixth lens is a biconvex lens. Distortion is corrected by using the first and second lenses; the third lens improves chromatic aberration and exhibits good stability under varying temperature conditions; the fourth, fifth, and sixth lenses correct the chromatic aberration of the system, resulting in high-quality imaging on the photosensitive chip. The reasonable arrangement of the five lenses ensures that the optical focal length FA and total optical length TTL of the video lens optical system satisfy the relationship: 0.1 ≤ FA / TTL ≤ 0.25, and the distortion rate is below 3%, thus providing a small-sized video lens with low distortion and capable of achieving 4K high resolution. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the video lens provided by the present invention;

[0020] Figure 2 for Figure 1 The MTF curve of the video lens in the image at room temperature (25℃);

[0021] Figure 3 for Figure 1 Distortion / field curvature of the video lens at room temperature (25℃);

[0022] Figure 4 for Figure 1 The MTF curve of the video lens at a low temperature of -40℃;

[0023] Figure 5 for Figure 1 The distortion / field curvature of the video camera at a low temperature of -40°C;

[0024] Figure 6 for Figure 1 The MTF curve of the video camera at a high temperature of 80°C;

[0025] Figure 7 for Figure 1 The distortion / field curvature of the video camera at a high temperature of 80°C.

[0026] Explanation of icon numbers:

[0027] label name label name 10 lens tube 4 Fourth lens 1 First lens 5 Fifth lens 2 Second lens 6 Sixth lens 3 Third lens 7 Photosensitive chip

[0028] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0031] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0032] Currently, many small video lenses are used for video conferencing and live streaming, and the requirements for image quality are further increasing. Module manufacturers generally need to correct lens distortion, which affects production efficiency, and they hope to further reduce lens distortion. At the same time, in order to obtain a greater depth of field or a wider shooting distance, they are often used with adjustable focusing devices. Currently, there are significant differences in the price of adjustable focusing devices on the market. To meet the demand for high image quality at low cost, this optical system was designed. Similar small video lenses generally have relatively poor image quality and distortion of 7% to 8%, requiring distortion correction in the back-end engineering. However, video lenses with better performance and lower distortion are generally larger in size, requiring a larger adjustable focusing device, which increases the overall cost.

[0033] To address the above problems, the present invention provides a video lens. Figures 1 to 7 This is a specific embodiment of the video lens provided by the present invention.

[0034] Please see Figure 1, the video lens has an object side and an image side that are oppositely arranged along the optical axis direction. The video lens includes a lens barrel and a lens group disposed within the lens barrel. The lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a photosensitive chip 7 arranged in sequence from the object side to the image side. Both the first lens 1 and the second lens 2 are meniscus lenses, and the concave surfaces of the first lens 1 and the second lens 2 face the image side; the third lens 3 is a biconvex lens; the fourth lens 4 is a biconvex lens; the fifth lens 5 is a biconcave lens; the sixth lens 6 is a biconvex lens; the video lens satisfies the following condition: 0.1 ≤ FA / TTL ≤ 0.25, where FA is the focal length of the video lens and TTL is the distance on the optical axis between the object side surface of the first lens 1 and the imaging surface of the video lens.

[0035] In the technical solution provided by the present invention, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a photosensitive chip 7 are arranged in sequence from the object side to the image side. The first lens 1 and the second lens 2 are provided to correct distortion; the third lens 3 improves chromatic aberration and has good stability in an environment with a large temperature difference; the fourth lens 4, the fifth lens 5, and the sixth lens 6 can correct the chromatic aberration of the system, so that the lens group finally obtains high-quality imaging on the photosensitive chip 7. Through the reasonable setting of five lenses, the optical focal length FA and the optical total length TTL of the optical system of the video lens satisfy the relational expression: 0.1 ≤ FA / TTL ≤ 0.25, and the distortion rate reaches below 3%, so as to provide a video lens with a small volume, a small distortion rate, and a 4K high pixel.

[0036] Specifically, in this embodiment, the video lens also satisfies the following condition: 1.0 < TTL / Φ1 < 1.8, where Φ1 is the maximum aperture of the video lens. It should be noted that the maximum aperture of the video lens is the thread diameter at the end of the lens barrel at the object side. Specifically, in this embodiment, the maximum aperture Φ1 of the video lens is set to 10 mm. Thus, the diameter of the video lens is small, and because 1.0 < TTL / Φ1 < 1.8, it can be seen that the optical total length of the video lens is between 10 mm and 18 mm, and it can be seen that the volume of the video lens is small, enabling the video lens to achieve miniaturization.

[0037] Specifically, in this embodiment, the video lens further satisfies the following condition: 0.8 < IM / Φ2 < 1.1, where IM is the size of the imaging surface of the video lens, and Φ2 is the thread diameter of the end of the lens barrel at the image side. Specifically, in this embodiment, Φ2 = 8 mm. Therefore, preferably, the size of the imaging surface of the video lens is set to be within the range of 6.4 mm to 8.8 mm. Since the external thread of the lens barrel of the video lens meets the requirement of a diameter of 8 mm, an M8 adjustable focusing device can be matched, so that the assembly is more convenient and the production cost is greatly reduced.

[0038] Specifically, in this embodiment, the refractive index of the first lens 1 is nd1, and the Abbe number of the first lens 1 is vd1, where 1.5 ≤ nd1 ≤ 1.9 and 20 ≤ vd1 ≤ 60, which can reduce spherical chromatic aberration and aberration, so the distortion parameter can be effectively reduced.

[0039] Specifically, because the resin lens has strong impact resistance, light weight and low cost, in this embodiment, the materials of the first lens 1, the second lens 2, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are plastics. By using plastic aspherical lenses, the cost can be effectively controlled, and the chromatic aberration of the lens can be well corrected. Under the condition of ensuring the control of purple fringing of the lens, infrared confocal can be achieved, and at the same time, the spherical aberration and sine aberration at the high magnification position can be corrected.

[0040] However, because the chemical properties of the plastic material are relatively unstable under the influence of environmental temperature, and its refractive index is weaker than that of the all-glass lens, resulting in a worse picture restoration degree than the all-glass lens. In order to ensure the stability of the video lens, in this embodiment, the material of the third lens 3 is glass. Since the glass lens is not easily affected by thermal expansion and contraction and does not have a focus shift phenomenon, the glass lens can well resist the problem of the lens being deformed by heat and maintain the high precision of the lens for a long time. The video lens uses a glass-plastic hybrid material, which not only saves cost, has strong impact resistance, but also ensures the stability of the system and the applicability at high and low temperatures.

[0041] Specifically, in this embodiment, the refractive index of the third lens 3 is nd3, and the Abbe number of the third lens 3 is vd3, where 1.84 ≤ nd3 ≤ 2.01 and 24 ≤ vd3 ≤ 30. The refractive index of the second lens 2 is nd2, the refractive index of the fifth lens 5 is nd5, the Abbe number of the second lens 2 is vd2, and the Abbe number of the fifth lens 5 is vd5, where 1.6 ≤ nd2 ≤ 1.7, 1.6 ≤ nd5 ≤ 1.7, 18 ≤ vd2 ≤ 19, and 18 ≤ vd5 ≤ 19. In this way, the chromatic aberration can be effectively improved, and it is ensured that the entire optical system can still form a clear image in an environment with a high temperature below 80° and a low temperature above -40°.

[0042] It is understood that the surface of the photosensitive chip 7 facing the object is the imaging surface.

[0043] The video lens also includes a filter, which is located between the sixth lens 6 and the imaging surface. The filter can effectively filter out stray light in non-working wavelength bands to reduce optical noise, reduce difficulties for subsequent optoelectronic module processing, and thus improve imaging quality.

[0044] Specifically, the imaging surface can be understood as the surface of the photosensitive chip 7 facing the object, that is, the surface of a camera element such as a CCD or CMOS. It can be understood that the light carrying the information of the object being photographed can pass through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 in sequence and finally be imaged on the imaging surface.

[0045] Specifically, in this embodiment, the surface shape, radius of curvature, and thickness of the lens are shown in Table 1:

[0046] Table 1

[0047]

[0048] Furthermore, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following condition:

[0049]

[0050] Where c is the curvature corresponding to the radius, y is the radial coordinate (its unit is the same as the lens length unit), and Conic(k) is the conic quadratic coefficient (when the coefficient k is less than -1, the surface curve is a hyperbola; when the coefficient k is equal to -1, it is a parabola; when the coefficient k is between -1 and 0, it is an ellipse; when the coefficient k is equal to 0, it is a circle; and when the coefficient k is greater than 0, it is an oval). Please refer to Tables 1 and 2. The shape and size of the aspherical surface of the object side and image side of the lens can be set by the above parameters.

[0051] Table 2 Conicity and Asphericity Coefficients for Aspherical Lenses

[0052]

[0053] Figure 2 The MTF curve of the video lens at room temperature (25°C); Figure 3 The distortion / field curvature of the video lens at room temperature (25°C); Figure 4 The MTF curve of the video lens at a low temperature of -40°C; Figure 5It is the distortion / field curvature diagram of the video lens at a low temperature of -40°C; Figure 6 It is the MTF curve diagram of the video lens at a high temperature of 80°C; Figure 7 It is the distortion / field curvature diagram of the video lens at a high temperature of 80°C.

[0054] As can be seen from the above figures, the spherical aberration, field curvature, and distortion of the video lens in this embodiment can all be well corrected.

[0055] In summary, the first lens 1 and the second lens 2 are set as meniscus plastic lenses, effectively reducing the distortion parameters. The third lens 3 is set as a glass spherical lens, ensuring that the entire optical system can still form a clear image in an environment where the temperature is below 80°C and above -40°C. The second lens 2, the third lens 3, and the fifth lens 5 effectively improve chromatic aberration. It is achieved that the video lens can satisfy 0.1 ≤ FA / TTL ≤ 0.25, 1.0 < TTL / Φ1 < 1.8, and 0.8 < IM / Φ2 < 1.1, making the video lens small in volume, with a small distortion rate after use, and capable of meeting the imaging requirements of 4K high pixels.

[0056] In addition, the present invention also provides an electronic device. The projection device includes the video lens described in the above technical solution. Since the projection device includes the video lens, the specific structure of this video lens refers to the above embodiment. Since the video lens of this projection device adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0057] Specifically, in this embodiment, the electronic device further includes a focusing device. The focusing device is disposed on the image side of the video lens and is used to adjust the focal length of the video lens. The focusing device can focus the light rays that sequentially pass through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6. Among them, the focusing device is externally threaded and screwed to the lens barrel of the video lens on the image side, and the internal thread of the focusing device is set to M8. In this way, it is more convenient for assembly, greatly reducing the production cost.

[0058] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A video lens, characterized in that, The video lens has an object side and an image side that are oppositely arranged along the optical axis direction. The video lens includes a lens barrel and a lens group disposed within the lens barrel. The lens group is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip arranged in sequence from the object side to the image side. The first lens and the second lens are both meniscus lenses, and the concave surfaces of the first lens and the second lens face the image side. The third lens is a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a convex-concave lens, and the sixth lens is a biconvex lens. The optical power of the first lens is negative, the optical power of the second lens is negative, and the optical power of the fifth lens is negative; The video lens satisfies the following condition: 0.1 ≤ FA / TTL ≤ 0.25, where FA is the optical focal length of the video lens, and TTL is the distance on the optical axis between the object side surface of the first lens and the imaging surface of the video lens; The video lens also satisfies the following condition: 1.0 < TTL / Φ1 < 1.8, where Φ1 is the maximum aperture of the video lens, that is, the thread diameter of the end of the lens barrel at the object side; The video lens also satisfies the following condition: 0.8 < IM / Φ2 < 1.1, where IM is the size of the imaging surface of the video lens, and Φ2 is the thread diameter of the end of the lens barrel at the image side; 2. The video lens as described in claim 1, characterized in that, Φ2 = 8 mm.

3. The video lens as described in claim 1, characterized in that, The refractive index of the first lens is nd1, and the Abbe number of the first lens is vd1, where 1.5 ≤ nd1 ≤ 1.9 and 20 ≤ vd1 ≤ 60.

4. The video lens as described in claim 1, characterized in that, The materials of the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are plastics; The material of the third lens is glass.

5. The video lens as described in claim 1, characterized in that, The refractive index of the third lens is nd3, and the Abbe number of the third lens is vd3, where 1.84 ≤ nd3 ≤ 2.01 and 24 ≤ vd3 ≤ 30.

6. The video lens as described in claim 1, characterized in that, The refractive index of the second lens is nd2, the refractive index of the fifth lens is nd5, the Abbe number of the second lens is vd2, and the Abbe number of the fifth lens is vd5, where 1.6 ≤ nd2 ≤ 1.7, 1.6 ≤ nd5 ≤ 1.7, vd2 = 23.91, and vd5 = 20.

38.

7. An electronic device, characterized in that, Including the video lens according to any one of claims 1 to 6.

8. The electronic device as claimed in claim 7, characterized in that, The electronic device further includes a focusing device, which is disposed on the image side of the video lens and is used to adjust the focal length of the video lens.

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