Optical system, imaging device and electronic device

Abstract

The present application provides an optical system, an imaging device and an electronic device. The optical system includes, in order from the object side to the image side along the optical axis: a first lens having positive refractive power, whose object side surface is convex at the near optical axis; a second lens having negative refractive power, whose object side surface is convex at the near optical axis, and whose image side surface is concave at the near optical axis; a third lens having refractive power; a fourth lens having refractive power, whose image side surface is convex at the near optical axis; a fifth lens having negative refractive power; a sixth lens having positive refractive power, whose image side surface is convex at the near optical axis; and a seventh lens having negative refractive power, whose object side surface is concave at the near optical axis, and whose image side surface is concave at the near optical axis, the object side surface and the image side surface of the seventh lens are both aspherical surfaces, and at least one of the object side surface and the image side surface is provided with at least one inflection point. The above optical system can achieve a balance in achieving a large image surface, high resolution and miniaturization when satisfying a specific relationship.

Description

Technical Field

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

[0002] At present, high-pixel camera functions have become the standard of portable devices, and photosensitive chips with up to 100 million pixels have appeared, making it possible to shoot ultra-high-quality images. The characteristics of this type of photosensitive chip are that the diagonal length is very large, the size of the pixels is smaller, and the number is larger.

[0003] However, traditional optical lenses have a small image surface and their resolution is not very outstanding, so it is difficult to meet the adaptation requirements of this type of photosensitive chips. Summary of the invention

[0004] Based on this, it is necessary to provide an improved optical system to address the problems of traditional optical lenses, such as small image surface, low resolution, and difficulty in adapting to ultra-high pixel photosensitive chips.

[0005] An optical system, the optical system comprising, in order from the object side to the image side along the optical axis:

[0006] The first lens has positive refractive power and its object side surface is convex near the optical axis;

[0007] The second lens has negative refractive power, its object side surface is convex at the near optical axis, and its image side surface is concave at the near optical axis;

[0008] The third lens has refractive power;

[0009] The fourth lens has refractive power and its image side surface is convex near the optical axis;

[0010] A fifth lens element having negative refractive power;

[0011] a sixth lens element having positive refractive power and an image-side surface thereof being convex near the optical axis; and

[0012] A seventh lens element having negative refractive power, wherein the object side surface is concave at the near optical axis, and the image side surface is concave at the near optical axis. Both the object side surface and the image side surface of the seventh lens element are aspherical surfaces, and at least one surface of the object side surface and the image side surface is provided with at least one inflection point;

[0013] The optical system satisfies the following relationship:

[0014] 0.26<(CT1+CT2+CT3+CT4) / TTL<0.29;

[0015] Wherein, CT1 represents the thickness of the first lens on the optical axis, CT2 represents the thickness of the second lens on the optical axis, CT3 represents the thickness of the third lens on the optical axis, CT4 represents the thickness of the fourth lens on the optical axis, and TTL represents the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis.

[0016] The above optical system can have a larger image surface by selecting an appropriate number of lenses and reasonably allocating the refractive power and surface shape of each lens. At the same time, it can enhance the imaging resolution capability of the lens and effectively correct aberrations to ensure the imaging quality of the image. In addition, when the above relationship is met, the thickness of the front lens group can be reasonably set to facilitate the molding and assembly of the lens, reduce the difficulty of manufacturing the lens, and also facilitate the reasonable allocation of the spacing between lenses, making the lens structure of the optical system more compact and realizing the miniaturization of the system.

[0017] In one embodiment, the d-light Abbe number of at least three lenses in the optical system is less than 30.

[0018] When the above relationship is met, the system's light collection ability can be enhanced by setting a high refractive index (i.e., low Abbe number) lens, which helps to converge the light into the system and focus it on the imaging surface, thereby ensuring the system's viewing angle and image surface brightness. At the same time, setting a low refractive index (i.e., high Abbe number) lens is beneficial for reducing system dispersion, thereby reducing chromatic aberration and improving image quality.

[0019] In one embodiment, the optical system satisfies the following relationship: ImgH≥6.34mm; wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

[0020] When the above relationship is met, a large-size image surface can be achieved, thereby ensuring that the above-mentioned optical system can match the chip with an ultra-large photosensitive area and ensure the high-pixel imaging effect of the lens. At the same time, it can also increase the photosensitive area corresponding to a single pixel point to meet the adaptation requirements of a larger light flux and improve the imaging quality under weak light.

[0021] In one embodiment, the optical system satisfies the following relationship: f / EPD≤1.85; wherein f represents the effective focal length of the optical system, and EPD represents the entrance pupil diameter of the optical system.

[0022] When the above relationship is met, the effective focal length and entrance pupil diameter of the optical system can be reasonably configured, and the front aperture can ensure that the system has sufficient light input, thereby improving the system's shooting effect in a dark light environment. In addition, increasing the aperture is also conducive to reducing the size of the Airy disk, thereby having a higher resolution limit and meeting the design requirements of ultra-high pixel optical systems.

[0023] In one embodiment, the optical system satisfies the following relationship: TTL / ImgH≤1.404; wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

[0024] ImgH determines the size of the photosensitive chip. The larger the ImgH is, the larger the size of the photosensitive chip that the optical system can support. Therefore, when the above relationship is met, ImgH can be reasonably increased to facilitate the system to adapt to high-pixel photosensitive chips. It is also beneficial to appropriately reduce TTL to compress the length of the entire optical system and keep the system structure compact.

[0025] In one embodiment, the optical system satisfies the following relationship: 1.2<TTL / f<1.3; wherein f represents the effective focal length of the optical system.

[0026] When the above relationship is met, the total length and effective focal length of the optical system can be reasonably configured, which is conducive to miniaturization of the optical system while obtaining the telephoto characteristic.

[0027] In one embodiment, the optical system satisfies the following relationship: |f / f4|≤1.2; wherein f represents the effective focal length of the optical system, and f4 represents the effective focal length of the fourth lens.

[0028] When the above relationship is met, the effective focal length of the optical system and the effective focal length of the fourth lens can be reasonably configured, so that the fourth lens can provide appropriate positive or negative refractive power, thereby adjusting the overall refractive power of the system, forming a quasi-symmetrical structure with the front first lens, the second lens and the third lens, balancing the distortion caused by the front lens group, and avoiding high-order aberrations caused by excessive refractive index.

[0029] In one embodiment, the optical system satisfies the following relationship: 0.2<|f6 / RS11|<0.9; wherein f6 represents the effective focal length of the sixth lens, and RS11 represents the curvature radius of the object side of the sixth lens at the optical axis.

[0030] When the above relationship is satisfied, it is beneficial to reasonably configure the effective focal length of the sixth lens element and the radius of curvature of the object side of the sixth lens element at the optical axis, thereby effectively improving the aberration produced by the front lens group and enhancing the resolution capability of the optical system.

[0031] In one embodiment, the optical system satisfies the following relationship: 1.6<∑CT / ∑AT<2.2; wherein ∑CT represents the sum of thicknesses of lenses in the optical system on the optical axis, and ∑AT represents the sum of air intervals between adjacent lenses in the optical system on the optical axis.

[0032] When the above relationship is met, the proportions of ∑CT and ∑AT in the optical system can be reasonably set, so that the light can achieve smooth transition on each mirror surface during the transmission process, which helps to improve the imaging quality of the optical system.

[0033] In one embodiment, the optical system satisfies the following relationship: 0.07<BF / TTL<0.12; wherein BF represents the minimum distance from the image side surface of the seventh lens to the imaging surface of the optical system in the optical axis direction.

[0034] When the above relationship is met, it is beneficial to reasonably set the optical back focus and the total length of the optical system, which is beneficial to the assembly of the lens module. It is also beneficial to reduce the incident angle of the main light in the edge area of ​​the imaging surface, increase the relative illumination of the image surface, and thus improve the imaging quality.

[0035] In one embodiment, the optical system satisfies the following relationship:

[0036] 0.35<|SAG72| / RS14<0.65; wherein, SAG72 represents the distance from the intersection of the image side surface of the seventh lens and the optical axis to the maximum effective aperture of the image side surface of the seventh lens in the direction of the optical axis, and RS14 represents the curvature radius of the image side surface of the seventh lens at the optical axis.

[0037] When the above relationship is met, the image side sag of the seventh lens and the curvature radius of the image side of the seventh lens at the optical axis can be reasonably configured, which is beneficial to reducing the structural complexity of the lens, improving the production yield, and also beneficial to reducing the high-order aberrations of the system.

[0038] The present application also provides an imaging device.

[0039] An imaging device comprises the above-mentioned optical system and a photosensitive element, wherein the photosensitive element is arranged on the image side of the optical system.

[0040] The above-mentioned imaging device, utilizing the aforementioned optical system, can adapt to photosensitive elements with ultra-large photosensitive areas, thereby capturing bright images with high pixels. At the same time, the imaging device also has the characteristics of a miniaturized structure, which is convenient for adaptation to devices with limited size such as mobile phones and tablets, thereby better meeting market demand.

[0041] The present application also provides an electronic device, comprising a housing and the imaging device as described above, wherein the imaging device is mounted on the housing.

[0042] The electronic device is lightweight and can achieve ultra-high pixel scene shooting effect by using the aforementioned imaging device, which is beneficial to improving the user's shooting experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic structural diagram of an optical system according to Embodiment 1 of the present application is shown;

[0044] Figure 2 The longitudinal spherical aberration curve, the astigmatism curve and the distortion curve of the optical system of Example 1 are respectively shown;

[0045] Figure 3 A schematic diagram of the structure of an optical system according to Embodiment 2 of the present application is shown;

[0046] Figure 4 The longitudinal spherical aberration curve, the astigmatism curve and the distortion curve of the optical system of Example 2 are respectively shown;

[0047] Figure 5 A schematic structural diagram of an optical system according to Embodiment 3 of the present application is shown;

[0048] Figure 6 The longitudinal spherical aberration curve, the astigmatism curve and the distortion curve of the optical system of Example 3 are respectively shown;

[0049] Figure 7 A schematic structural diagram of an optical system according to Embodiment 4 of the present application is shown;

[0050] Figure 8 The longitudinal spherical aberration curve, the astigmatism curve and the distortion curve of the optical system of Example 4 are respectively shown;

[0051] Fig. 9 A schematic structural diagram of an optical system according to Embodiment 5 of the present application is shown;

[0052] Fig.10 The longitudinal spherical aberration curve, the astigmatism curve and the distortion curve of the optical system of Example 5 are respectively shown;

[0053] Fig.11 A schematic diagram of an imaging device according to an embodiment of the present application is shown;

[0054] Fig.12 A schematic diagram of an electronic device using an imaging device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0055] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to understand the disclosure of the present invention more thoroughly and comprehensively.

[0056] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right", "upper", "lower", "front", "rear", "circumferential" and similar expressions used herein are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0058] In this specification, the expressions first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens. For ease of explanation, the shapes of spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of spherical or aspherical surfaces are not limited to the shapes of spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0059] In this specification, the side space where the object is located relative to the optical element is called the object side of the optical element, and correspondingly, the side space where the image of the object is located relative to the optical element is called the image side of the optical element. The surface closest to the object in each lens is called the object side, and the surface closest to the imaging surface in each lens is called the image side. The distance from the object side to the image side is defined as the positive direction.

[0060] In addition, in the following description, if the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least near the optical axis; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least near the optical axis. Here, the near optical axis refers to the area near the optical axis. Specifically, the concave and convexity of the lens surface area is determined by whether the intersection of the light rays passing through the area in parallel with the optical axis is on the image side or the object side. For example, when the parallel light rays pass through the area, the light rays focus toward the image side and the intersection with the optical axis is on the image side, then the area is convex; conversely, if the light rays diverge after passing through the area and the intersection of the extended line of the light rays with the optical axis is on the object side, then the area is concave. In addition, the lens includes an area near the optical axis, an area near the circumference, and an extension for fixing the lens. Ideally, the imaging light rays do not pass through the extension, so the area range from the area near the optical axis to the area near the circumference can be defined as the effective aperture range of the lens. In the following embodiments, some extension parts are omitted for simplicity of the drawings. Further, the method for determining the range of the area near the optical axis, the area near the circumference, or multiple areas is as follows:

[0061] First, define a center point as an intersection point with the optical axis on the lens surface, the distance from the center point to the boundary of the lens effective aperture range is the effective semi-aperture of the lens, and an inflection point is a point located on the lens surface but not on the optical axis, and a tangent line through the inflection point is perpendicular to the optical axis (i.e., the surface shapes on both sides of the inflection point on the lens surface are opposite). If there are several inflection points from the center point in the radial direction of the lens, they are the first inflection point, the second inflection point, and the inflection point farthest from the center point in the effective aperture range of the lens is the Nth inflection point. Define the range between the center point and the first inflection point as the area near the optical axis, the area radially outward from the Nth inflection point as the area near the circumference, and the area between the first inflection point and the Nth inflection point is divided into different areas according to each inflection point; if there is no inflection point on the lens surface, the area near the optical axis is defined as the area corresponding to 0% to 50% of the effective semi-aperture, and the area near the circumference is defined as the area corresponding to 50% to 100% of the effective semi-aperture.

[0062] The features, principles and other aspects of the present application will be described in detail below.

[0063] Please also read Figure 1 , Figure 3 , Figure 5 , Figure 7 and Fig. 9, the present application provides an optical system with a large image surface and high resolution. The optical system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens. The seven lenses are arranged in sequence from the first lens to the seventh lens along the optical axis from the object side to the image side, and the imaging surface of the optical system is located on the image side of the seventh lens. In detail, the seven lenses are non-joined, that is, there is a spacing between any two adjacent lenses. Since the manufacturing process of the joined lens is more complicated than that of the non-joined lens, especially the joining surface of the two lenses needs to have a high-precision curved surface (such as an aspheric surface) in order to achieve a high degree of closeness when the two lenses are joined, and during the joining process, the poor closeness may also be caused by deviation, affecting the overall optical imaging quality. Therefore, the seven lenses in the optical system of the present invention are non-joined lenses, which can effectively improve the problems caused by the joined lenses.

[0064] Specifically, the first lens has positive refractive power, which is conducive to the light converging into the system and focusing on the imaging surface, and also helps to shorten the total length of the system and realize the miniaturization of the system. Furthermore, the object side of the first lens is convex at the near optical axis, which helps to enhance the positive refractive power provided by the first lens.

[0065] The second lens has negative refractive power, which helps to correct the spherical aberration produced by the first lens and further expand the field of view of the optical system. Furthermore, the object side of the second lens is convex near the optical axis, and the image side is concave near the optical axis, which helps to prevent over-correction of the spherical aberration and chromatic aberration of the first lens.

[0066] The third lens has refractive power. When the third lens has positive refractive power, it can help the first lens share part of the positive refractive power, avoid excessive bending of the first lens, make the adjacent lens surfaces more matched, and further shorten the total length of the system. When the third lens has negative refractive power, it helps the optical system to further diffuse the light, allowing the light to enter the lens below more smoothly, thereby reducing the generation of high-order aberrations.

[0067] The fourth lens has a refractive power, which can effectively balance the refractive power of the front lens group, thereby improving the distortion caused by the first lens, the second lens and the third lens, and also helps to reduce the high-order aberrations caused by the excessive refractive index of the lens. Furthermore, the image side of the fourth lens is convex at the near optical axis, which is conducive to focusing light, thereby shortening the total length of the system and ensuring the miniaturization of the system.

[0068] The fifth lens has negative refractive power, which can expand the light emitted by the front lens group, and the appropriate negative refractive power helps to smoothly transition the light, thereby further improving the imaging quality.

[0069] The sixth lens has positive refractive power, which can effectively improve the aberration produced by the front lens group and enhance the resolving power of the optical system. The image side surface of the sixth lens is convex near the optical axis, which helps to enhance the positive refractive power provided by the sixth lens to better correct the chromatic aberration produced by the front lens group.

[0070] The seventh lens has negative refractive power, which helps to correct the system aberrations and adjust the optical back focus of the system, thereby providing sufficient matching space for the photosensitive chip, facilitating the assembly and adjustment of the photosensitive chip, so as to better achieve the matching of the incident angle of the main light on the photosensitive chip and improve the imaging quality of the system. Furthermore, the object side of the seventh lens is concave at the near optical axis, and the image side is concave at the near optical axis, which helps to further enhance the negative refractive power provided by the seventh lens and appropriately increase the optical back focus of the system.

[0071] Furthermore, both the object side and the image side of the seventh lens are aspherical. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better imaging characteristics and has the advantages of improving edge aberrations and astigmatism field curvature. Through the above-mentioned method, the flexibility of lens design can be improved, and aberrations can be effectively corrected to improve the imaging quality of the optical system. Furthermore, at least one surface of the object side and the image side of the seventh lens is provided with at least one inflection point, which is conducive to reducing the incident angle of the main light of the off-axis field of view on the imaging plane, improving the response efficiency of the pixel unit in the edge area of ​​the photosensitive chip, and improving the relative illumination, thereby reducing the generation of off-axis field aberrations and improving the imaging resolution capability of the system.

[0072] Further, the optical system satisfies the following relationship: 0.26<(CT1+CT2+CT3+CT4) / TTL<0.29; wherein CT1 represents the thickness of the first lens on the optical axis, CT2 represents the thickness of the second lens on the optical axis, CT3 represents the thickness of the third lens on the optical axis, CT4 represents the thickness of the fourth lens on the optical axis, and TTL represents the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis. (CT1+CT2+CT3+CT4) / TTL can be 0.265, 0.27, 0.275, 0.28, 0.285 or 0.288. When the above relationship is met, the thickness of the front lens group can be reasonably set to facilitate the molding and assembly of the lens, reduce the difficulty of manufacturing the lens, and also facilitate the reasonable distribution of the spacing between the lenses, so that the lens structure of the optical system is more compact and the system is miniaturized. When (CT1+CT2+CT3+CT4) / TTL is lower than the lower limit, some lenses may be too thin, unable to effectively control light, and reduce image quality. It is also easy to increase the distance between lenses, which is not conducive to the miniaturization of the system. When (CT1+CT2+CT3+CT4) / TTL is higher than the upper limit, some lenses may be too thick, the air distance is too small, and the lenses are prone to touch, which increases the difficulty of manufacturing and assembling the lenses.

[0073] When the above optical system is used for imaging, light emitted or reflected by the object enters the optical system from the object side, and passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens in sequence, and finally converges on the imaging surface.

[0074] The above optical system can have a larger image surface by selecting an appropriate number of lenses and reasonably allocating the refractive power and surface shape of each lens. At the same time, it can enhance the imaging resolution capability of the lens and effectively correct aberrations to ensure the imaging quality of the image. When a specific relationship is met, the thickness of the front lens group can be reasonably set to facilitate the molding and assembly of the lens, reduce the difficulty of manufacturing the lens, and is also conducive to the reasonable allocation of the spacing between lenses, making the lens structure of the optical system more compact and realizing the miniaturization of the system.

[0075] In an exemplary embodiment, the object side and image side of the first lens to the seventh lens may both be aspherical surfaces. The characteristics of aspherical lenses have been described in the previous text and will not be repeated here. Through the above method, the flexibility of lens design can be improved, and aberrations can be effectively corrected to improve the imaging quality of the optical system. Setting the object side and image side of the first lens to the seventh lens as aspherical surfaces can better correct the aberrations generated during the light transmission process. It should be pointed out that, without deviating from the technical solution of the optical system of the present application, the surface of each lens can also be any combination of spherical and aspherical surfaces, and the present application does not limit this.

[0076] In an exemplary embodiment, the d-light Abbe number of at least three lenses in the optical system is less than 30. Wherein, the wavelength of the d-light is 587.56nm, and the three lenses can be the second lens, the fourth lens, and the fifth lens. When the above relationship is met, the light collection ability of the system can be enhanced by setting a high refractive index (i.e., low Abbe number) lens, which helps to converge the light into the system and focus on the imaging surface, ensuring the viewing angle and image brightness of the system, and at the same time, by setting a low refractive index (i.e., high Abbe number) lens, it is beneficial to reduce the dispersion of the system, thereby reducing chromatic aberration (such as purple fringing) and improving the imaging quality of the image. The combination of high and low refractive index lenses can effectively reduce dispersion while the system is focused on imaging, ensuring the imaging quality of the image.

[0077] In an exemplary embodiment, the optical system satisfies the following relationship: ImgH ≥ 6.34mm; wherein ImgH represents half of the image height corresponding to the maximum field of view angle of the optical system. Furthermore, half of the maximum field of view angle in the present application refers to the angle between the light incident at the maximum viewing angle and the optical axis of the system. ImgH can be 6.34mm, 6.36mm, 6.38mm, 6.40mm, 6.42mm, 6.44mm or 6.46mm. When the above relationship is met, the system can have a large-size image plane, thereby ensuring that the optical system can match the chip with a large photosensitive area and ensure the ultra-high pixel imaging effect of the lens. At the same time, it can also increase the photosensitive area corresponding to a single pixel point and improve image quality. When ImgH is lower than the lower limit, it is more difficult to match a chip with a large photosensitive area, and it is difficult to achieve an ultra-high pixel shooting effect.

[0078] In an exemplary embodiment, the optical system satisfies the following relationship: f / EPD≤1.85; wherein f represents the effective focal length of the optical system, and EPD represents the entrance pupil diameter of the optical system. f / EPD can be 1.79, 1.80, 1.81, 1.82, 1.83, 1.84 or 1.85. When the above relationship is met, the effective focal length and entrance pupil diameter of the optical system can be reasonably configured, and the system can be ensured to have sufficient light input by pre-positioning the aperture, thereby improving the shooting effect of the system in a dark light environment; in addition, an increase in the aperture is also conducive to reducing the size of the Airy disk, thereby having a higher resolution limit and meeting the design requirements of an ultra-high pixel optical system. When f / EPD is higher than the upper limit, the aperture of the system is small, the imaging quality is not high, and it is not conducive to shooting in a low-light environment.

[0079] In an exemplary embodiment, the optical system satisfies the following relationship: TTL / ImgH≤1.404; wherein ImgH represents half of the image height corresponding to the maximum field angle of the optical system. TTL / ImgH can be 1.32, 1.33, 1.34, 1.36, 1.38, 1.39, 1.40, 1.402 or 1.404. ImgH determines the size of the photosensitive chip. The larger the ImgH, the larger the size of the photosensitive chip that the optical system can support. Therefore, when the above relationship is met, ImgH can be reasonably increased, so that the system can be adapted to high-pixel photosensitive chips. At the same time, it is also beneficial to appropriately reduce TTL to compress the length of the entire optical system and keep the system compact. When TTL / ImgH is higher than the upper limit, it is easy to cause the total length of the system to become longer, which is not conducive to miniaturization.

[0080] In an exemplary embodiment, the optical system satisfies the following relationship: 1.2<TTL / f<1.3; wherein f represents the effective focal length of the optical system. TTL / f can be 1.22, 1.24, 1.25, 1.26, 1.27, 1.28 or 1.29. The total length is positively correlated with the focal length, and a long focal length will inevitably lead to an increase in the total optical length. Therefore, when the above relationship is satisfied, the total length and effective focal length of the optical system can be reasonably configured, which is conducive to miniaturization of the optical system while obtaining the telephoto characteristic. When TTL / f is lower than the lower limit, it is easy to cause the focal length of the system to be too long and it is difficult to compress the total length of the system; and when TTL / f is higher than the upper limit, it is not conducive to obtaining the telephoto characteristic of the system.

[0081] In an exemplary embodiment, the optical system satisfies the following relationship: |f / f4|≤1.2; wherein f represents the effective focal length of the optical system, and f4 represents the effective focal length of the fourth lens. |f / f4| can be 2.85E-4, 0.2, 0.25, 0.3, 0.5, 0.8, 1.1, 1.12, 1.14, 1.16, 1.18 or 1.2. When the above relationship is satisfied, the effective focal length of the optical system and the effective focal length of the fourth lens can be reasonably configured, so that the fourth lens can provide appropriate positive or negative refractive power to adjust the overall refractive power of the system, form a quasi-symmetrical structure with the front first lens, the second lens and the third lens, balance the distortion generated by the front lens group, and avoid high-order aberrations caused by excessive refractive index. When |f / f4| is higher than the upper limit, the effective focal length of the fourth lens is short, and the refractive power provided is too large, which is not conducive to balancing the overall refractive power of the system, and easily leads to excessive aberration correction and reduced imaging quality.

[0082] In an exemplary embodiment, the optical system satisfies the following relationship: 0.2<|f6 / RS11|<0.9; wherein f6 represents the effective focal length of the sixth lens, and RS11 represents the radius of curvature of the object side of the sixth lens at the optical axis. |f6 / RS11| can be 0.202, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.82, 0.84, 0.86 or 0.88. When the above relationship is satisfied, it is beneficial to reasonably configure the effective focal length of the sixth lens and the radius of curvature of the object side of the sixth lens at the optical axis, so as to effectively improve the aberration generated by the front lens group and enhance the resolution of the optical system. When |f6 / RS11| is lower than the lower limit, the effective focal length of the sixth lens is small, the positive refractive power is strong, and high-order aberrations are easily introduced; when |f6 / RS11| is higher than the lower limit, the radius of curvature of the object side of the sixth lens at the optical axis is small, and the lens surface is over-curved, which is not conducive to the molding and assembly of the lens.

[0083] In an exemplary embodiment, the optical system satisfies the following relationship: 1.6<∑CT / ∑AT<2.2; wherein ∑CT represents the sum of the thickness of each lens on the optical axis in the optical system, and ∑AT represents the sum of the air intervals of each adjacent lens on the optical axis in the optical system. ∑CT / ∑AT can be 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, 2.05, 2.1 or 2.15. When the above relationship is satisfied, the proportion of ∑CT and ∑AT in the optical system can be reasonably set, so that the light can achieve a smooth transition on each mirror surface during the transmission process, which helps to improve the imaging quality of the optical system. When ∑CT / ∑AT is lower than the lower limit, it is easy to cause the lens to be too thin, and the lens cannot effectively control the light, resulting in reduced imaging quality; When ∑CT / ∑AT is higher than the upper limit, it is easy to cause the lens to be too thick, which is not conducive to the convergence and diffusion of light between the lenses, forcing the lens to change the light trend in a more curved shape, increasing the difficulty of manufacturing the lens.

[0084] In an exemplary embodiment, the optical system satisfies the following relationship: 0.07<BF / TTL<0.12; wherein BF represents the minimum distance from the image side of the seventh lens to the imaging plane of the optical system in the direction of the optical axis. BF / TTL can be 0.075, 0.08, 0.09, 0.095, 0.10, 0.11 or 0.115. When the above relationship is met, it is beneficial to reasonably set the optical back focus and the total length of the system of the optical system, which is beneficial to the assembly of the lens module, and it is also beneficial to reduce the incident angle of the main light in the edge area of ​​the imaging surface, improve the relative illumination of the image surface, and thus improve the imaging quality. When BF / TTL is lower than the lower limit, it is easy to cause the optical back focus to be too small, the installation space of the lens module is insufficient, and it is not conducive to suppressing the incident angle of the main light; when BF / TTL is higher than the upper limit, it is easy to cause the optical back focus to be too large, which is not conducive to the miniaturization of the system and the assembly of the lens module.

[0085] In an exemplary embodiment, the optical system satisfies the following relationship: 0.35<|SAG72| / RS14<0.65; wherein, SAG72 represents the distance from the intersection of the image side surface of the seventh lens and the optical axis to the maximum effective aperture of the image side surface of the seventh lens in the direction of the optical axis, and RS14 represents the radius of curvature of the image side surface of the seventh lens at the optical axis. |SAG72| / RS14 can be 0.36, 0.38, 0.4, 0.45, 0.5, 0.55, 0.6, 0.62 or 0.64. When the above relationship is met, the image side surface sagittal height of the seventh lens and the radius of curvature of the image side surface of the seventh lens at the optical axis can be reasonably configured, which is conducive to reducing the structural complexity of the lens, improving the production yield, and also helping to reduce the high-order aberrations of the system. When |SAG72| / RS14 is lower than the lower limit or higher than the upper limit, it is easy to cause the lens shape to be too curved, which increases the difficulty of manufacturing the lens, and is not conducive to light control, and it is difficult to ensure the imaging quality.

[0086] In an exemplary embodiment, a stop is also provided in the optical system to better control the size of the incident light beam and improve the imaging quality of the optical system. Further, the stop is provided on the object side of the first lens. Preferably, the stop is an aperture stop. The aperture stop may be located on the surface of the lens (e.g., the object side and the image side) and form an operative relationship with the lens, for example, by coating a light-blocking coating on the surface of the lens to form an aperture stop on the surface; or by fixing the surface of the lens with a clamp, the clamp structure located on the surface can limit the width of the imaging beam of the object point on the axis, thereby forming an aperture stop on the surface.

[0087] In an exemplary embodiment, a filter is further provided between the seventh lens and the imaging surface of the optical system to filter out light in a non-working band, thereby preventing false color or ripples from being generated due to interference from light in a non-working band, and avoiding color distortion in the image. Specifically, the filter may be an infrared cutoff filter made of glass.

[0088] In an exemplary embodiment, the material of each lens in the optical system can be glass or plastic. The plastic lens can reduce the weight of the optical system and reduce the production cost, while the glass lens can make the optical system have better temperature tolerance and excellent optical performance. Furthermore, when the optical system is applied to a mobile phone or tablet, the material of each lens is preferably plastic, so as to reduce the weight of the optical system and reduce the production cost while meeting the imaging performance. It should be noted that the material of each lens in the optical system can also be any combination of glass and plastic, and it does not have to be all glass or all plastic.

[0089] In an exemplary embodiment, the optical system may further include a protective glass. The protective glass is disposed on the image side of the seventh lens or the image side of the filter to protect the photosensitive element and prevent the photosensitive element from being contaminated by dust, thereby further ensuring the imaging quality. It should be noted that when the optical system is applied to electronic devices such as mobile phones and tablets, the protective glass may not be provided to further reduce the weight of the electronic device.

[0090] The optical system of the above-mentioned embodiment of the present application may use multiple lenses, such as the seven lenses described above. By reasonably allocating the focal length, refractive power, surface shape, thickness of each lens and the on-axis spacing between each lens, the above-mentioned optical system can have large image surface, small total length and high resolution characteristics, and also have a large aperture (FNO can be 1.79) and light weight, so as to better meet the application requirements of electronic devices such as mobile phones and tablets. However, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses constituting the optical system can be changed to obtain the various results and advantages described in this specification.

[0091] Specific embodiments of the optical system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0092] Example 1

[0093] The following reference Figure 1 to Figure 2 An optical system 100 according to Embodiment 1 of the present application is described.

[0094] Figure 1 FIG. 1 is a schematic diagram showing the structure of the optical system 100 of Example 1. Figure 1As shown, the optical system 100 includes, in order from the object side to the image side along the optical axis, 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 imaging surface S17.

[0095] The first lens L1 has positive refractive power, and its object side surface S1 and image side surface S2 are both aspherical surfaces, wherein the object side surface S1 is convex near the optical axis and is convex near the circumference, and the image side surface S2 is concave near the optical axis and is concave near the circumference.

[0096] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces, wherein the object-side surface S3 is convex near the optical axis and is convex near the circumference, and the image-side surface S4 is concave near the optical axis and is concave near the circumference.

[0097] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces, wherein the object-side surface S5 is concave near the optical axis and is concave near the circumference, and the image-side surface S6 is convex near the optical axis and is convex near the circumference.

[0098] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces, wherein the object-side surface S7 is concave near the optical axis and is concave near the circumference, and the image-side surface S8 is convex near the optical axis and is convex near the circumference.

[0099] The fifth lens L5 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces, wherein the object-side surface S9 is convex near the optical axis and is concave near the circumference, and the image-side surface S10 is concave near the optical axis and is convex near the circumference.

[0100] The sixth lens L6 has positive refractive power, and its object-side surface S11 and image-side surface S12 are both aspherical surfaces, wherein the object-side surface S11 is convex near the optical axis and is concave near the circumference, and the image-side surface S12 is convex near the optical axis and is convex near the circumference.

[0101] The seventh lens L7 has negative refractive power, and its object-side surface S13 and image-side surface S14 are both aspherical surfaces, wherein the object-side surface S13 is concave near the optical axis and is concave near the circumference, and the image-side surface S14 is concave near the optical axis and is convex near the circumference.

[0102] Setting the object-side surface and the image-side surface of the first lens L1 to the seventh lens L7 as aspherical surfaces is beneficial to correcting aberrations and solving the problem of image distortion, and can also enable the lenses to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical system 100 miniaturized.

[0103] A stop STO is also provided on the object side of the first lens L1 to limit the size of the incident light beam, further improving the imaging quality of the optical system 100. The optical system 100 also includes a filter 110 provided on the image side of the seventh lens L7 and having an object side surface S15 and an image side surface S16. The light from the object OBJ passes through each surface S1 to S16 in sequence and is finally imaged on the imaging surface S17. The filter 110 is used to filter out light in non-working bands, thereby preventing the generation of false colors or ripples due to interference from light in non-working bands and avoiding color distortion of the imaging. Specifically, the filter 110 is an infrared cutoff filter, and its material is glass.

[0104] Table 1 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of the lens of the optical system 100 of Example 1, wherein the reference wavelength of the refractive index and Abbe number is 587.56 nm, the reference wavelength of the effective focal length is 555 nm, and the units of the radius of curvature, thickness, and effective focal length of the lens are all millimeters (mm). In addition, the first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance from the image side of the lens to the next surface in the image side direction on the optical axis; the value of the aperture ST0 in the "thickness" parameter column is the distance from the aperture ST0 to the vertex of the next surface (the vertex refers to the intersection of the surface and the optical axis) on the optical axis. We assume that the direction from the object side of the first lens L1 to the image side of the last lens is the positive direction of the optical axis. When the value is negative, it indicates that the aperture ST0 is set at Figure 1 The aperture is on the right side of the surface vertex. If the aperture STO thickness is a positive value, the aperture is on the left side of the surface vertex.

[0105] Table 1

[0106]

[0107]

[0108] The aspheric surface shape in a lens is defined by the following formula:

[0109]

[0110] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1); k is the cone coefficient; Ai is the i-th order coefficient of the aspheric surface. The following Table 2 lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for the aspheric surfaces S1-S14 of the lens in Example 1.

[0111] Table 2

[0112]

[0113] Combining the data in Table 1 and Table 2, it can be seen that the optical system 100 in Example 1 satisfies:

[0114] (CT1+CT2+CT3+CT4) / TTL=0.268, wherein CT1 represents the thickness of the first lens L1 on the optical axis, CT2 represents the thickness of the second lens L2 on the optical axis, CT3 represents the thickness of the third lens L3 on the optical axis, CT4 represents the thickness of the fourth lens L4 on the optical axis, and TTL represents the distance from the object-side surface S1 of the first lens L1 to the imaging surface of the optical system 100 on the optical axis;

[0115] ImgH=6.46 mm, where ImgH represents half of the image height corresponding to the maximum field angle of the optical system 100;

[0116] f / EPD=1.819, where f represents the effective focal length of the optical system 100, and EPD represents the entrance pupil diameter of the optical system 100;

[0117] TTL / ImgH=1.331;

[0118] TTL / f=1.289, where f represents the effective focal length of the optical system 100;

[0119] |f / f4|=0.269, wherein f represents the effective focal length of the optical system 100, and f4 represents the effective focal length of the fourth lens L4;

[0120] |f6 / RS11|=0.591, wherein f6 represents the effective focal length of the sixth lens L6, and RS11 represents the radius of curvature of the object-side surface S11 of the sixth lens L6 at the optical axis;

[0121] ∑CT / ∑AT=1.872, where ∑CT represents the sum of the thicknesses of the lenses in the optical system 100 on the optical axis, and ∑AT represents the sum of the air intervals between adjacent lenses in the optical system 100 on the optical axis;

[0122] BF / TTL=0.08, where BF represents the minimum distance between the image-side surface S14 of the seventh lens L7 and the imaging surface S17 of the optical system 100 in the optical axis direction;

[0123] |SAG72| / RS14=0.515, wherein SAG72 represents the distance from the intersection of the image side surface S14 of the seventh lens L7 and the optical axis to the maximum effective aperture of the image side surface S14 of the seventh lens L7 in the optical axis direction, and RS14 represents the curvature radius of the image side surface S14 of the seventh lens L7 at the optical axis.

[0124] Figure 2 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 100 of Example 1 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focal point of light rays with wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism curve shows the meridional (T) image curvature and sagittal (S) image curvature of light rays with a wavelength of 555nm after passing through the optical system 100; the distortion curve shows the distortion of light rays with a wavelength of 555nm at different image heights after passing through the optical system 100. Figure 2 It can be seen that the optical system 100 provided in Example 1 can achieve good imaging quality.

[0125] Example 2

[0126] The following reference Figure 3 to Figure 4 The optical system 100 of the second embodiment of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of the first embodiment will be omitted.

[0127] Figure 3 FIG. 2 shows a schematic diagram of the structure of an optical system 100 according to Embodiment 2 of the present application. Figure 3 As shown, the optical system 100 includes, in order from the object side to the image side along the optical axis, 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 imaging surface S17.

[0128] The first lens L1 has positive refractive power, and its object side surface S1 and image side surface S2 are both aspherical surfaces, wherein the object side surface S1 is convex near the optical axis and is convex near the circumference, and the image side surface S2 is concave near the optical axis and is concave near the circumference.

[0129] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces, wherein the object-side surface S3 is convex near the optical axis and is convex near the circumference, and the image-side surface S4 is concave near the optical axis and is concave near the circumference.

[0130] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces, wherein the object-side surface S5 is convex near the optical axis and is convex near the circumference, and the image-side surface S6 is convex near the optical axis and is convex near the circumference.

[0131] The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces, wherein the object-side surface S7 is concave near the optical axis and is concave near the circumference, and the image-side surface S8 is convex near the optical axis and is convex near the circumference.

[0132] The fifth lens L5 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces, wherein the object-side surface S9 is convex near the optical axis and is concave near the circumference, and the image-side surface S10 is concave near the optical axis and is convex near the circumference.

[0133] The sixth lens L6 has positive refractive power, and its object-side surface S11 and image-side surface S12 are both aspherical surfaces, wherein the object-side surface S11 is convex near the optical axis and is concave near the circumference, and the image-side surface S12 is convex near the optical axis and is convex near the circumference.

[0134] The seventh lens L7 has negative refractive power, and its object-side surface S13 and image-side surface S14 are both aspherical surfaces, wherein the object-side surface S13 is concave near the optical axis and is concave near the circumference, and the image-side surface S14 is concave near the optical axis and is convex near the circumference.

[0135] The materials of the first lens L1 to the seventh lens L7 are all plastic. A stop STO is also provided on the object side of the first lens L1 to limit the size of the incident light beam, further improving the imaging quality of the optical system 100. The optical system 100 also includes a filter 110 provided on the image side of the seventh lens L7 and having an object side surface S15 and an image side surface S16. The light from the object OBJ passes through each surface S1 to S16 in sequence and is finally imaged on the imaging surface S17. Specifically, the filter 110 is an infrared cutoff filter, and its material is glass.

[0136] Table 3 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of each lens of the optical system 100 of Example 2, wherein the reference wavelength of the refractive index and the Abbe number is 587.56 nm, the reference wavelength of the effective focal length is 555 nm, and the units of the radius of curvature, thickness, and effective focal length of each lens are all millimeters (mm); Table 4 shows the high-order coefficients of the aspheric surfaces S1-S14 of the lenses that can be used in Example 2, wherein the aspheric surface shape can be defined by the formula (1) given in Example 1.

[0137] Table 3

[0138]

[0139] Table 4

[0140]

[0141] Figure 4The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 100 of Example 2 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focal point of light rays with wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism curve shows the meridional (T) image curvature and sagittal (S) image curvature of light rays with a wavelength of 555nm after passing through the optical system 100; the distortion curve shows the distortion of light rays with a wavelength of 555nm at different image heights after passing through the optical system 100. Figure 4 It can be seen that the optical system 100 provided in Example 2 can achieve good imaging quality.

[0142] Example 3

[0143] The following reference Figures 5 and 6 The optical system 100 of the third embodiment of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of the first embodiment will be omitted.

[0144] Figure 5 FIG. 1 is a schematic diagram showing the structure of an optical system 100 according to Embodiment 3 of the present application. Figure 5 As shown, the optical system 100 includes, in order from the object side to the image side along the optical axis, 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 imaging surface S17.

[0145] The first lens L1 has positive refractive power, and its object side surface S1 and image side surface S2 are both aspherical surfaces, wherein the object side surface S1 is convex near the optical axis and is convex near the circumference, and the image side surface S2 is concave near the optical axis and is concave near the circumference.

[0146] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces, wherein the object-side surface S3 is convex near the optical axis and is convex near the circumference, and the image-side surface S4 is concave near the optical axis and is concave near the circumference.

[0147] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces, wherein the object-side surface S5 is concave near the optical axis and is concave near the circumference, and the image-side surface S6 is convex near the optical axis and is convex near the circumference.

[0148] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces, wherein the object-side surface S7 is concave near the optical axis and is concave near the circumference, and the image-side surface S8 is convex near the optical axis and is convex near the circumference.

[0149] The fifth lens L5 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces, wherein the object-side surface S9 is convex near the optical axis and is concave near the circumference, and the image-side surface S10 is concave near the optical axis and is convex near the circumference.

[0150] The sixth lens L6 has positive refractive power, and its object-side surface S11 and image-side surface S12 are both aspherical surfaces, wherein the object-side surface S11 is convex near the optical axis and is concave near the circumference, and the image-side surface S12 is convex near the optical axis and is convex near the circumference.

[0151] The seventh lens L7 has negative refractive power, and its object-side surface S13 and image-side surface S14 are both aspherical surfaces, wherein the object-side surface S13 is concave near the optical axis and is concave near the circumference, and the image-side surface S14 is concave near the optical axis and is convex near the circumference.

[0152] The materials of the first lens L1 to the seventh lens L7 are all plastic. A stop STO is also provided on the object side of the first lens L1 to limit the size of the incident light beam, further improving the imaging quality of the optical system 100. The optical system 100 also includes a filter 110 provided on the image side of the seventh lens L7 and having an object side surface S15 and an image side surface S16. The light from the object OBJ passes through each surface S1 to S16 in sequence and is finally imaged on the imaging surface S17. Specifically, the filter 110 is an infrared cutoff filter, and its material is glass.

[0153] Table 5 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of each lens of the optical system 100 of Example 3, wherein the reference wavelength of the refractive index and the Abbe number is 587.56 nm, the reference wavelength of the effective focal length is 555 nm, and the units of the radius of curvature, thickness, and effective focal length of each lens are all millimeters (mm); Table 6 shows the high-order coefficients of the aspheric surfaces S1-S14 of the lenses that can be used in Example 3, wherein the aspheric surface shape can be defined by the formula (1) given in Example 1.

[0154] Table 5

[0155]

[0156]

[0157] Table 6

[0158]

[0159] Figure 6The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 100 of Example 3 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focal point of light rays with wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism curve shows the meridional (T) image curvature and sagittal (S) image curvature of light rays with a wavelength of 555nm after passing through the optical system 100; the distortion curve shows the distortion of light rays with a wavelength of 555nm at different image heights after passing through the optical system 100. Figure 6 It can be seen that the optical system 100 provided in Example 3 can achieve good imaging quality.

[0160] Example 4

[0161] The following reference Figures 7 and 8 The optical system 100 of Embodiment 4 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Embodiment 1 will be omitted.

[0162] Figure 7 FIG. 4 shows a schematic diagram of the structure of an optical system 100 according to Embodiment 4 of the present application. Figure 7 As shown, the optical system 100 includes, in order from the object side to the image side along the optical axis, 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 imaging surface S17.

[0163] The first lens L1 has positive refractive power, and its object side surface S1 and image side surface S2 are both aspherical surfaces, wherein the object side surface S1 is convex near the optical axis and is convex near the circumference, and the image side surface S2 is concave near the optical axis and is concave near the circumference.

[0164] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces, wherein the object-side surface S3 is convex near the optical axis and is convex near the circumference, and the image-side surface S4 is concave near the optical axis and is concave near the circumference.

[0165] The third lens L3 has negative refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces, wherein the object-side surface S5 is concave near the optical axis and is concave near the circumference, and the image-side surface S6 is convex near the optical axis and is convex near the circumference.

[0166] The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces, wherein the object-side surface S7 is concave near the optical axis and is concave near the circumference, and the image-side surface S8 is convex near the optical axis and is concave near the circumference.

[0167] The fifth lens L5 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces, wherein the object-side surface S9 is concave near the optical axis and is concave near the circumference, and the image-side surface S10 is convex near the optical axis and is convex near the circumference.

[0168] The sixth lens L6 has positive refractive power, and its object-side surface S11 and image-side surface S12 are both aspherical surfaces, wherein the object-side surface S11 is concave near the optical axis and is concave near the circumference, and the image-side surface S12 is convex near the optical axis and is convex near the circumference.

[0169] The seventh lens L7 has negative refractive power, and its object-side surface S13 and image-side surface S14 are both aspherical surfaces, wherein the object-side surface S13 is concave near the optical axis and is concave near the circumference, and the image-side surface S14 is concave near the optical axis and is convex near the circumference.

[0170] The materials of the first lens L1 to the seventh lens L7 are all plastic. A stop STO is also provided on the object side of the first lens L1 to limit the size of the incident light beam, further improving the imaging quality of the optical system 100. The optical system 100 also includes a filter 110 provided on the image side of the seventh lens L7 and having an object side surface S15 and an image side surface S16. The light from the object OBJ passes through each surface S1 to S16 in sequence and is finally imaged on the imaging surface S17. Specifically, the filter 110 is an infrared cutoff filter, and its material is glass.

[0171] Table 7 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of each lens of the optical system 100 of Example 4, wherein the reference wavelength of the refractive index and the Abbe number is 587.56 nm, the reference wavelength of the effective focal length is 555 nm, and the units of the radius of curvature, thickness, and effective focal length of each lens are all millimeters (mm); Table 8 shows the high-order coefficients of the aspheric surfaces S1-S14 of the lenses that can be used in Example 4, wherein the aspheric surface shape can be defined by the formula (1) given in Example 1.

[0172] Table 7

[0173]

[0174]

[0175] Table 8

[0176]

[0177] Figure 8The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 100 of Example 4 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focal point of light rays with wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism curve shows the meridional (T) image curvature and sagittal (S) image curvature of light rays with a wavelength of 555nm after passing through the optical system 100; the distortion curve shows the distortion of light rays with a wavelength of 555nm at different image heights after passing through the optical system 100. Figure 8 It can be seen that the optical system 100 provided in Example 4 can achieve good imaging quality.

[0178] Example 5

[0179] The following reference Figures 9 and 10 The optical system 100 of Embodiment 5 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Embodiment 1 will be omitted.

[0180] Fig. 9 FIG. 5 shows a schematic diagram of the structure of an optical system 100 according to Embodiment 5 of the present application. Fig. 9 As shown, the optical system 100 includes, in order from the object side to the image side along the optical axis, 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 imaging surface S17.

[0181] The first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces, wherein the object-side surface S1 is convex near the optical axis and is convex near the circumference, and the image-side surface S2 is convex near the optical axis and is concave near the circumference.

[0182] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces, wherein the object-side surface S3 is convex near the optical axis and is convex near the circumference, and the image-side surface S4 is concave near the optical axis and is concave near the circumference.

[0183] The third lens L3 has negative refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces, wherein the object-side surface S5 is concave near the optical axis and is concave near the circumference, and the image-side surface S6 is concave near the optical axis and is convex near the circumference.

[0184] The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces, wherein the object-side surface S7 is convex near the optical axis and is concave near the circumference, and the image-side surface S8 is convex near the optical axis and is convex near the circumference.

[0185] The fifth lens L5 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces, wherein the object-side surface S9 is concave near the optical axis and is concave near the circumference, and the image-side surface S10 is concave near the optical axis and is convex near the circumference.

[0186] The sixth lens L6 has positive refractive power, and its object-side surface S11 and image-side surface S12 are both aspherical surfaces, wherein the object-side surface S11 is convex near the optical axis and is concave near the circumference, and the image-side surface S12 is convex near the optical axis and is convex near the circumference.

[0187] The seventh lens L7 has negative refractive power, and its object-side surface S13 and image-side surface S14 are both aspherical surfaces, wherein the object-side surface S13 is concave near the optical axis and is concave near the circumference, and the image-side surface S14 is concave near the optical axis and is convex near the circumference.

[0188] The materials of the first lens L1 to the seventh lens L7 are all plastic. A stop STO is also provided on the object side of the first lens L1 to limit the size of the incident light beam, further improving the imaging quality of the optical system 100. The optical system 100 also includes a filter 110 provided on the image side of the seventh lens L7 and having an object side surface S15 and an image side surface S16. The light from the object OBJ passes through each surface S1 to S16 in sequence and is finally imaged on the imaging surface S17. Specifically, the filter 110 is an infrared cutoff filter, and its material is glass.

[0189] Table 9 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of each lens of the optical system 100 of Example 5, wherein the reference wavelength of the refractive index and the Abbe number is 587.56 nm, the reference wavelength of the effective focal length is 555 nm, and the units of the radius of curvature, thickness, and effective focal length of each lens are all millimeters (mm); Table 10 shows the high-order coefficients of the aspheric surfaces S1-S14 of the lenses that can be used in Example 5, wherein the aspheric surface shape can be defined by the formula (1) given in Example 1.

[0190] Table 9

[0191]

[0192]

[0193] Table 10

[0194]

[0195] Fig.10The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 100 of Example 5 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focal point of light rays with wavelengths of 470nm, 510nm, 555nm, 610nm and 655nm after passing through the optical system 100; the astigmatism curve shows the meridional (T) image curvature and sagittal (S) image curvature of light rays with a wavelength of 555nm after passing through the optical system 100; the distortion curve shows the distortion of light rays with a wavelength of 555nm at different image heights after passing through the optical system 100. Fig.10 It can be seen that the optical system 100 provided in Example 5 can achieve good imaging quality.

[0196] Table 11 shows the numerical values ​​of the above-mentioned embodiments corresponding to the correlation equations of the present invention.

[0197] Table 11

[0198] Example 1 Example 2 Example 3 Example 4 Example 5 f(mm) 6.67 6.89 7.24 6.92 6.86 FNO 1.82 1.79 1.8 1.8 1.85 FOV(deg) 86.85 84.92 82.06 83.58 84.12 TTL(mm) 8.6 8.7 8.84 8.9 8.89 ImgH(mm) 6.46 6.46 6.34 6.34 6.34 (CT1+CT2+CT3+CT4) / TTL 0.268 0.274 0.266 0.288 0.282 f / EPD 1.819 1.79 1.80 1.80 1.85 TTL / ImgH 1.331 1.347 1.394 1.404 1.402 TTL / f 1.289 1.262 1.221 1.286 1.297 |f / f4| 0.269 0.130 2.85E-4 1.181 1.151 |f6 / RS11| 0.591 0.810 0.845 0.398 0.202 ∑CT / ∑AT 1.872 2.096 1.683 2.132 2.118 BF / TTL 0.08 0.079 0.095 0.112 0.081 |SAG72| / RS14 0.515 0.384 0.387 0.567 0.629

[0199] like Fig.11 As shown, the present application also provides an imaging device 200, including the optical system 100 as described above (as shown in FIG. 1 ); and a photosensitive element 210, the photosensitive element 210 is arranged on the image side of the optical system 100, and the photosensitive surface of the photosensitive element 210 coincides with the imaging surface S17. Specifically, the photosensitive element 210 can be a complementary metal oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor, and the imaging surface S17 can be a plane or a curved surface with any curvature, especially a curved surface with a concave surface facing the object side, depending on the corresponding photosensitive element 210.

[0200] In some other implementations, the imaging device 200 further includes a lens barrel (not shown) for carrying the optical system 100 and a corresponding supporting device (not shown).

[0201] In addition, the imaging device 200 also includes a driving device (not shown) and an image stabilization module (not shown). The driving device may have an auto-focus function, and its driving method may use a driving system such as a voice coil motor (VCM), a micro electro-mechanical system (MEMS), a piezoelectric system (Piezoelectric), and a shape memory alloy. The driving device allows the optical system 100 to obtain a better imaging position, so that the subject can be photographed at different object distances to obtain a clear image; the image stabilization module may be an accelerometer, a gyroscope, or a Hall Effect Sensor. The driving device and the image stabilization module together serve as an optical image stabilization (OIS) device, which adjusts the displacement of the optical system 100 on the optical axis to compensate for the blurred image caused by shaking at the moment of shooting, or uses the image compensation technology in the image software to provide an electronic image stabilization (EIS) function to further improve the image quality of dynamic and low-light scene shooting.

[0202] The imaging device 200 can adapt to a photosensitive element with a large photosensitive area by using the aforementioned optical system 100, so as to capture a bright image with high pixels. At the same time, the imaging device 200 also has the structural characteristics of miniaturization and lightness. The imaging device 200 can be applied to the fields of mobile phones, automobiles, monitoring, and medical treatment. Specifically, it can be used as a mobile phone camera, a car camera, a monitoring camera, or an endoscope, etc., and has a wide range of market applications.

[0203] like Fig.12 As shown, the present application further provides an electronic device 300, including a housing 310 and the imaging device 200 as described above, and the imaging device 200 is mounted on the housing 310. Specifically, the imaging device 200 is disposed in the housing 310 and exposed from the housing 310 to acquire images, and the housing 310 can provide the imaging device 200 with protection such as dustproof, waterproof and drop-proof, and a hole corresponding to the imaging device 200 is opened on the housing 310 to allow light to pass into or out of the housing from the hole.

[0204] The electronic device 300 is lightweight and can capture ultra-high pixel images using the imaging device 200, which is beneficial to improving the user's shooting experience. In other embodiments, the electronic device 300 is also provided with a corresponding processing system. After capturing the image of the object, the electronic device 300 can promptly transmit the image to the corresponding processing system so that the system can make accurate analysis and judgment.

[0205] In other embodiments, the "electronic device" used may also include, but is not limited to, a device configured to receive or send communication signals via a wired line connection and / or via a wireless interface. An electronic device configured to communicate via a wireless interface may be referred to as a "wireless communication terminal", "wireless terminal" or "mobile terminal". Examples of mobile terminals include, but are not limited to, satellite or cellular phones; personal communication system (PCS) terminals that can combine cellular radio telephones with data processing, fax and data communication capabilities; personal digital assistants (PDAs) that can include radiotelephones, pagers, Internet / intranet access, web browsers, notepads, calendars and / or global positioning system (GPS) receivers; and conventional laptop and / or handheld receivers or other electronic devices including radiotelephone transceivers. In addition, "electronic devices" may also include three-dimensional image capture devices, digital cameras, tablet computers, smart TVs, network monitoring equipment, driving recorders, reversing development devices, multi-lens devices, identification systems, somatosensory game consoles and wearable devices. The above-mentioned electronic device is only an exemplary embodiment of the practical application of the present invention, and is not intended to limit the application scope of the imaging device of the present application.

[0206] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0207] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical system, characterized in that: There are seven lenses with refractive power. The optical system includes the following in order from the object side to the image side along the optical axis: The first lens has positive refractive power and its object side surface is convex near the optical axis; The second lens has negative refractive power, its object side surface is convex at the near optical axis, and its image side surface is concave at the near optical axis; The third lens has refractive power; The fourth lens has refractive power and its image side surface is convex near the optical axis; A fifth lens element having negative refractive power; a sixth lens element having positive refractive power and an image-side surface thereof being convex near the optical axis; and a seventh lens element having negative refractive power, wherein the object side surface is concave at the near optical axis, and the image side surface is concave at the near optical axis, wherein both the object side surface and the image side surface of the seventh lens element are aspherical surfaces, and at least one surface of the object side surface and the image side surface is provided with at least one inflection point; The optical system satisfies the following relationship: 0.26<(CT1+CT2+CT3+CT4) / TTL<0.29; Wherein, CT1 represents the thickness of the first lens on the optical axis, CT2 represents the thickness of the second lens on the optical axis, CT3 represents the thickness of the third lens on the optical axis, CT4 represents the thickness of the fourth lens on the optical axis, and TTL represents the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis; The optical system also satisfies the following relationship: 1.2<TTL / f<1.3; 1.6<∑CT / ∑AT<2.2; Wherein, f represents the effective focal length of the optical system; ∑CT represents the sum of the thicknesses of the lenses in the optical system on the optical axis; and ∑AT represents the sum of the air intervals between adjacent lenses in the optical system on the optical axis.

2. The optical system according to claim 1, characterized in that In the optical system, at least three lenses have d-light Abbe numbers lower than 30.

3. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: ImgH≥6.34mm; Wherein, ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

4. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 1.79≤f / EPD≤1.85; Wherein, f represents the effective focal length of the optical system, and EPD represents the entrance pupil diameter of the optical system.

5. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 1.331≤TTL / ImgH≤1.404; Wherein, ImgH represents half of the image height corresponding to the maximum field angle of the optical system.

6. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: |f / f4|≤1.2; Wherein, f represents the effective focal length of the optical system, and f4 represents the effective focal length of the fourth lens.

7. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 0.2<|f6 / RS11|<0.9; Wherein, f6 represents the effective focal length of the sixth lens, and RS11 represents the curvature radius of the object side of the sixth lens at the optical axis.

8. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 0.07<BF / TTL<0.12; Wherein, BF represents the minimum distance from the image side surface of the seventh lens to the imaging surface of the optical system in the optical axis direction.

9. The optical system according to claim 1, characterized in that The optical system satisfies the following relationship: 0.35<|SAG72| / RS14<0.65; Among them, SAG72 represents the distance from the intersection of the image side surface of the seventh lens and the optical axis to the maximum effective aperture of the image side surface of the seventh lens in the direction of the optical axis, and RS14 represents the curvature radius of the image side surface of the seventh lens at the optical axis.

10. An imaging device, characterized in that: It comprises the optical system as described in any one of claims 1 to 9 and a photosensitive element, wherein the photosensitive element is arranged on the image side of the optical system.

11. An electronic device, characterized in that: It comprises a housing and the imaging device as claimed in claim 10, wherein the imaging device is mounted on the housing.

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