CN211528811U - Lens, imaging system and electronic equipment - Google Patents

Abstract

The utility model provides a camera lens, imaging system and electronic equipment, the camera lens includes seven lenses of arranging in proper order along the optical axis, first to fourth lens constitute first mirror group, the fifth lens constitutes second mirror group, sixth lens with the seventh lens constitute third mirror group, the focus of first mirror group with the second mirror group is positive, the focus of third mirror group is negative, and be provided with the diaphragm between first and the second mirror group; the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all spherical glass lenses, and the first lens and the seventh lens are aspheric glass lenses; the lens meets the following parameter conditions: FOV is more than or equal to 24.8 degrees and less than or equal to 35.6 degrees, and NA is more than or equal to 0.250 and less than or equal to 0.292; f' is more than or equal to 5.5 and less than or equal to 8.5. The utility model discloses a camera lens technology is simple relatively, and image quality is good, does not have obvious distortion and colour difference problem, and it is big to throw the picture, and camera lens F number is littleer and thermal stability can be better.

Description

Lenses, Imaging Systems and Electronics

technical field

The utility model relates to the technical field of optical imaging, in particular to a lens, an imaging system and an electronic device.

Background technique

With the advancement of video technology, more and more electronic devices work with lens components, such as projectors, scanners, 3D printers. Taking the projector as an example, it mainly uses DMD, LCOS or LCD as the display device, and uses the polarization beam splitter (PBS) or total reflection beam splitter (TIR) as the illumination and imaging beam splitting device. The image reflected on the display device is focused on the display screen. For LCOS and LCD projection optical systems, they have a common feature that they need a telecentric beam to illuminate the imaging chip, and of course, a projection lens with a telecentric optical path is required. Matching, this can better ensure the uniformity of the image surface illumination. Since the TIR or PBS prism is used to achieve effective illumination, the projection lens needs to retain a long rear working distance when it is matched, which greatly increases the lens. Difficulty in controlling length and off-axis aberrations leads to complex lenses with a large number of lenses, making assembly tolerances difficult to control.

In the prior art, in order to achieve good display image quality and large screen size (in the case of projection ratio <1.5), the projection lens usually has a complex structure and a large volume, and the number of lenses is generally more than 14 pieces. In order to improve, an aspherical lens is used on the image surface side of the lens, and at least two lenses are required for various lens groups, but this solution also requires at least nine or eight lenses, and the processing and assembly processes are still relatively complex. Difficult to control, expensive and display image quality is uneven. And all use spherical lenses, the projection is relatively large, when applied to a larger display screen, the resolution is low, the distortion is serious, and the image quality is poor, which cannot meet the market demand.

Utility model content

Based on the above situation, the main purpose of the present invention is to provide a lens, an imaging system and an electronic device to overcome the complicated processing and assembly process, low resolution, large distortion and poor imaging effect caused by too many lenses in the prior art. and other issues that cannot meet market demand.

For achieving the above object, the technical scheme adopted by the present utility model is as follows:

A first aspect of the present invention provides a lens, the lens has a first side and a second side along an optical axis direction, the lens includes a first side to a second side sequentially arranged along the optical axis the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens, the first lens, the second lens, the third lens and the Four lenses constitute a first mirror group, the fifth lens constitutes a second mirror group, the sixth lens and the seventh lens constitute a third mirror group, the first mirror group and the second mirror group The focal length is positive, the focal length of the third mirror group is negative, and a diaphragm is arranged between the first mirror group and the second mirror group;

The second to sixth lenses are spherical glass lenses, and the first lens and the seventh lens are aspherical glass lenses;

The first lens is a biconvex positive lens; the second lens is a crescent negative lens with both the first and second refracting surfaces concave to the second side; the third lens is a biconvex positive lens; the The fourth lens is a crescent negative lens with the first and second refracting surfaces both concave to the first side; the fifth lens is a double-convex positive lens; the sixth lens is a double-concave negative lens or the first and second lenses. The second refracting surface is concave to the first side of the crescent negative lens; the seventh lens is the crescent negative lens whose first and second refracting surfaces are both concave to the first side; wherein, the first refracting surface of each lens refers to It is the refracting surface close to the first side, and the second refracting surface refers to the refracting surface that is close to the second side;

The lens satisfies the following parameter conditions:

24.8°≤FOV.≤35.6°,

0.250≤NA≤0.292,

5.5≤f'≤8.5;

The refractive index of the first lens is less than 1.7, and the Abbe number is greater than 55;

The refractive index of the seventh lens is greater than 1.5, and the Abbe number is greater than 50.

Wherein: FOV. represents the image-side half-field angle of the lens, NA represents the object-side numerical aperture of the lens; f' is the focal length of the lens, in mm.

Preferably, the lens satisfies the following parameter conditions:

1.47≤f' _A /f'≤2.44,

1.148≤f' _B /f'≤2.452,

-1.21≤f' _C /f'≤-0.80,

Wherein, f' _A , f' _B , and f' _c are the focal lengths of the first mirror group, the second mirror group, and the third mirror group, respectively, and the unit is mm.

Preferably, the second lens, the third lens and the fourth lens are laminated in sequence to form a triplet lens; the focal length of the triplet lens is negative;

The refractive index of the second lens and the refractive index of the fourth lens are both greater than 1.7, and the refractive index of the third lens is less than 1.6;

The Abbe number of the second lens is less than 45, the Abbe number of the third lens is greater than 70, and the Abbe number of the fourth lens is less than 40.

Preferably, the first mirror group also satisfies:

0.95≤f ₁ '/f' _A ≤1.3,

-102≤f _glued '/f' _A≤10.65 ,

Wherein, f ₁ ′ and f _cemented are respectively the focal lengths of the first lens and the triplet lens, and the unit is mm.

Preferably, the triplet lens satisfies:

-0.15≤f ₂ '/f _{glued'≤0.05} ,

_-0.05≤f3 '/ _{fglued'≤0.15} ,

-0.2≤f ₄ '/f _{glued'≤0.05} ,

0.6≤f ₂ '/f ₄ '≤1.7;

Wherein, f ₂ ′, f ₃ ′, and f ₄ ′ are the focal lengths of the second lens, the third lens, and the fourth lens, respectively, and the unit is mm.

Preferably, the first mirror group also satisfies:

The center thickness T of the triplet lens satisfies: _{0.815≤T cement} /f'≤1.278;

The central thickness T1 of the first lens satisfies: 0.443≤T1/f'≤0.563;

The axial distance D1 between the first lens and the triplet lens satisfies: 0.014≤D1/f'≤0.023;

Among them, the unit of T _glue , T1, D1 is mm.

Preferably, the first mirror group also satisfies:

The radii R ₁₁ and R ₁₂ of the first refracting surface and the second refracting surface in the first lens satisfy: 1.455≤R ₁₁ /f'≤2.44, -11.759≤R ₁₂ /f'≤-3.394;

The radii R ₂₁ and R ₂₂ of the first refracting surface and the second refracting surface in the second lens satisfy: 1.245≤R ₂₁ /f'≤2.412, 0.759≤R ₂₂ /f'≤1.021;

The radii R ₃₁ and R ₃₂ of the first refracting surface and the second refracting surface in the third lens satisfy: 0.759≤R ₃₁ /f'≤1.021, -1.884≤R ₃₂ /f'≤-1.379;

The radii R ₄₁ and R ₄₂ of the first refracting surface and the second refracting surface in the fourth lens satisfy: -1.884≤R ₄₁ /f'≤-1.379, -17.895≤R ₄₂ /f'≤-5.004;

The units of R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , R ₄₁ , and R ₄₂ are all mm.

Preferably, the refractive index of the fifth lens is greater than 1.55, and the Abbe coefficient is less than 40;

The central thickness T5 of the fifth lens satisfies: 0.308≤T5/f'≤0.654;

The radii R51 and R52 of the first refractive surface and the second refractive surface in the fifth lens satisfy: 1.748≤R51/ _f'≤3.555 , _-3.513≤R52 /f'≤-2.146;

The units of T5, R ₅₁ , and R ₅₂ are mm.

Preferably, the third mirror group satisfies:

1.85≤f ₆ '/f' _C ≤2.4,

2.2≤f ₇ '/f' _C ≤2.5;

Wherein, f ₆ ′ and f ₇ ′ are the focal lengths of the sixth lens and the seventh lens, respectively, and the unit is mm.

Preferably, the third mirror group satisfies:

0.75≤f ₆ '/f ₇ '≤1.05;

The axial distance D6 between the sixth lens and the seventh lens satisfies: 0.414≤D6/f'≤0.818;

Wherein, f ₆ ′ and f ₇ ′ are the focal lengths of the sixth lens and the seventh lens, respectively, and the units of f ₆ ′, f ₇ ′, and D6 are all mm.

Preferably,

The radii R61 and R62 of the first refractive surface and the second refractive surface in the sixth lens satisfy: -1.541≤R61/ _f'≤ -1.192, _R62 /f'≤-4.965 or _R62 /f'≥1.918 ;

The radii R71 and R72 of the first refractive surface and the second refractive surface in the seventh lens satisfy: -0.653≤R71/ _f'≤ -0.343, _-1.395≤R72 /f'≤-0.636;

The units of R ₆₁ , R ₆₂ , R ₇₁ , and R ₇ are all mm.

Preferably, the respective first and second refractive surfaces of the first lens and the seventh lens satisfy:

Among them, Z represents the distance from the point on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis; r represents the distance from the point on the aspheric surface to the optical axis; c represents the central curvature of the aspheric surface; k represents the conic rate; a4, a6, a8, a10, a12, a14, and a16 represent aspherical high-order coefficients.

Preferably,

The axial distance D4 between the first mirror group and the diaphragm satisfies: 0.575≤D4/f'≤1.152;

The axial distance DS between the diaphragm and the second mirror group satisfies: 0.371≤DS/f'≤0.594;

The axial distance D5 between the second mirror group and the third mirror group satisfies: 0.098≤D5/f'≤1.035;

The units of D4, DS, and D5 are all mm.

In the lens of the present invention, two aspherical lenses are respectively used on the frontmost side and the rearmost side of the lens, which can respectively replace several spherical lenses on both sides, and the first lens group uses a combination of four lenses, and the second lens group uses a combination of four lenses. One biconvex lens, and the third lens group uses a combination of three lenses. After this setting, compared with the use of multiple lenses for each lens group and the use of spherical lenses for each lens, it is possible to make the first side of the lens and the third lens. Under the condition that the two sides meet the same focal length, the axial size of the entire lens is greatly reduced, the distortion is reduced, and a smaller focal length can be obtained, so that the projection ratio of the lens is smaller; at the same time, all glass lenses are used to increase the lens's projection ratio. The light transmittance ensures sufficient light energy in the imaging process. Compared with some lenses using plastic lenses, the utility model can improve the defocusing caused by the temperature of the lens.

A second aspect of the present invention provides an imaging system, comprising a display device, a light splitting device, and the lens according to any one of the above arranged sequentially, and the display device and the light splitting device are all located at a position of the lens. first side.

Preferably, the display device includes a DMD, LCOS or LCD display device; the size of the display device is less than or equal to 0.3 inches.

A third aspect of the present invention provides an electronic device, including the imaging system described in any one of the above.

Other beneficial effects of the present invention will be described in the specific embodiments through the introduction of specific technical features and technical solutions. Those skilled in the art should be able to understand the technical features and technical solutions through the introduction of these technical features and technical solutions. beneficial technical effects.

Description of drawings

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the picture:

1 is a schematic structural diagram of a preferred embodiment of an imaging system provided by the present invention;

2 is a schematic structural diagram of a preferred embodiment of the lens provided by the present invention;

3-5 are schematic structural diagrams of Embodiments 1, 2, and 3, respectively.

In the picture:

1. Display device;

2. Protective glass;

3. Spectroscopic device;

4. Lens; A, the first lens group; L1, the first lens; L2, the second lens; L3, the third lens; L4, the fourth lens; B, the second lens group; L5, the fifth lens; C, The third lens group; L6, the sixth lens; L7, the seventh lens; S diaphragm;

5. Image surface.

Detailed ways

The present invention is described below based on examples, but the present invention is not limited to these examples. In the following detailed description of the present invention, some specific details are described in detail. In order to avoid obscuring the essence of the present invention, well-known methods, procedures, processes, and elements are not described in detail.

Furthermore, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Unless clearly required by the context, words such as "including", "comprising" and the like throughout the specification and claims should be construed in an inclusive rather than an exclusive or exhaustive sense; that is, "including but not limited to" meaning.

In the description of the present invention, it should be understood that the terms "first", "second" and the like are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

In addition, the units of focal length, radius, center thickness and on-axis distance in the present invention are all mm, and the radius is the radius of curvature of the lens. The reciprocal of the curvature of the The distance between the two adjacent surfaces on the optical axis; for an aspheric lens, it refers to its spherical center, which refers to the spherical center of the curved surface where the aspheric surface is close to the optical axis (that is, intersecting with the optical axis). And for the sake of description, the lens coordinate system is established, and the direction of the first side along the optical axis is defined as "negative", and the direction of the second side is "positive", that is, in Figure 1, the direction along the optical axis is positive. , negative to the left. Among them, the meanings of the parameters in the text and the table are as follows: FOV.: the image-side half-field angle of the lens, NA: the object-side numerical aperture of the lens; Nd: refractive index; Vd: Abbe number; f': the focal length of the lens , in mm; f _i ': the focal length of the i-th lens, in mm; R _ij : the radius of the j-th refraction surface of the i-th lens, in mm; with reference to Figure 1, Ti: the i-th lens's radius Center thickness, in mm; Di: the distance between the i-th lens and its adjacent lenses in the positive direction or the two adjacent optical surfaces of the optical component in the optical axis direction, in mm; The distance between the two adjacent optical surfaces of a lens on the optical axis, in mm; DS: the distance between the diaphragm and the adjacent two optical surfaces of the fifth lens along the optical axis, D0 and DS are in mm. In addition, the above i and j are 1, 2, . . . , 7, respectively.

The utility model provides an electronic device, such as a projection device, a 3D printing device, a scanning device and other imaging devices, which includes an imaging system. As shown in FIG. 1 , the imaging system includes a display device 1 , a light splitting device 3 and The lens 4 is arranged along the optical axis of the lens 4 , wherein the display device 1 and the light splitting device 3 are both located on the first side of the lens 4 .

The display device 1 may include any one of DMD (Digital Micromirror Device, digital micro mirror device), LCOS (Liquid Crystal on Silicon, liquid crystal on silicon) display, or LCD (Liquid Crystal Display, liquid crystal display), specifically, display The size of the device 1 can be 0.45 inches, 0.3 inches or less than 0.3 inches, and the display device 1 can be in the form of a chip. To protect it, a protective glass 2 can be arranged between the display device 1 and the spectroscopic device 3 . The spectroscopic device 3 may in particular comprise a prism. Of course, the imaging system also has an image plane 5. When the lens 4 is used in a projection device, the image plane 5 is a projection plane, such as a projection cloth or a wall.

The lens 4 has a first side and a second side along the optical axis. When applied to projection equipment, scanning equipment and 3D printing equipment, the first side can be set as the object side, the second side as the image side, and the display device 1, Both the protective glass 2 and the spectroscopic device 3 are located on the first side. Of course, according to the principle of reversibility of the optical path, in actual use, the first side can also be the image side and the second side can be the object side, which can be set according to specific needs. The following description takes the first side as the object side and the second side as the image side as an example.

The lens includes a lens barrel (not shown in the figure) and a plurality of lenses, which are arranged in sequence along the optical axis and installed in the lens barrel. In the prior art, in order to obtain better imaging quality, the lens is provided with three, four or more mirror groups, each mirror group includes at least two lenses, and usually each lens is a spherical lens, therefore, at least the More than eight lenses are combined together, which increases the assembly process of the lens, and in this way, the axial dimension (dimension along the optical axis) of the assembled lens is relatively large, which is not conducive to the application of small equipment; When it is applied to a small display device with a size of less than 0.45 inches, the resolution is too poor.

To this end, the utility model has developed a lens 4 that can be applied to small-sized display devices. Specifically, referring to FIGS. 2-5 , the lens includes a lens from the first side to the second side (that is, the lens from left to right in the figure). direction) the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the first lens L1, the third lens L7, the The second lens L2, the third lens L3 and the fourth lens L4 form the first lens group A, the fifth lens L5 forms the second lens group B, the sixth lens L6 and the seventh lens L7 form the third lens group C, and the first lens The focal lengths of the group A and the second mirror group B are positive, the focal length of the third mirror group C is negative, and a diaphragm S is provided between the first mirror group A and the second mirror group B. Referring to Table 1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are spherical glass lenses, the first lens L1 and the seventh lens L7 are aspheric glass lenses, wherein , the first lens L1 is a biconvex positive lens; the second lens L2 is a crescent negative lens with both the first and second refractive surfaces concave to the second side; the third lens L3 is a biconvex positive lens; the fourth lens L4 is the first 1. The second refracting surface is concave to the first side of the crescent negative lens; the fifth lens L5 is a biconvex positive lens; the sixth lens L6 is a biconcave negative lens or both the first and second refracting surfaces are concave to the first side The seventh lens L7 is a negative crescent lens with both the first and second refracting surfaces concave to the first side; wherein, the first refracting surface of the lens refers to the refracting surface close to the first side, and the second refracting surface Refers to its refracting surface close to the second side. The above lenses meet the following parameters:

24.8°≤FOV.≤35.6°,

0.250≤NA≤0.292,

5.5≤f'≤8.5,

The refractive index of the first lens L1 is less than 1.7, and the Abbe number is greater than 55;

The refractive index of the seventh lens L7 is greater than 1.5, and the Abbe number is greater than 50.

The above-mentioned lens 4 only has three lens groups, and the first lens group A only uses five lenses, the second lens group B only uses one lens, and the third lens group C only uses two lenses, so that the number of lenses in the lens 4 is reduced. Significantly reduced, the impact of assembly tolerances on the resolution of the lens 4 is reduced, and the axial dimension of the lens 4 is significantly shortened, which can adapt to the development trend of electronic devices toward miniaturization and miniaturization.

Moreover, each lens of the lens of the present invention adopts an all-glass design, so that the light transmittance of the entire lens 4 is good, higher light energy can be output, the utilization rate of light is improved, and no vignetting setting is required, which achieves better performance. The uniformity of the image surface illumination, the relative illumination difference between the central field of view and the edge field of view can be controlled within 2%, the light utilization efficiency is high, and the brightness of the imaging is improved; at the same time, the thermal stability of the lens can be improved, and the lens heat can be avoided as much as possible. The phenomenon of defocus caused by deformation occurs, thereby reducing the impact of ambient temperature on the imaging effect of the lens and improving the adaptability of the lens. In the present invention, the diaphragm S is arranged between the first mirror group A and the second mirror group B, so that the overall structure of the lens 4 is relatively symmetrical, which can effectively balance coma and distortion, and further improve the imaging quality of the lens 4 .

Considering that such few lenses may cause larger projection ratio and distortion of the lens, the present invention uses a combination of five spherical lenses and two aspherical lenses, and sets the two aspherical lenses on two of the lens 3 respectively. The outermost part can effectively reduce distortion and improve imaging quality. In the imaging system, the projection ratio=projection distance/frame length. In the case of a certain projection distance, the smaller the projection ratio, the larger the frame length, which means that a larger frame is projected. The larger the field angle will be, the image-side field of view of the lens in the present invention is in the range of 24.8° to 35.6°, the object-side numerical aperture is in the range of 0.250 to 0.292, and the focal length is in the range of 5.5 to 8.5. It is used in conjunction with the display device 1 such as DMD or LCOS and the corresponding illumination light path to collect and focus the light beam reflected by the display device 1 to the image surface such as the display screen. Advantages, especially for a display device 1 with a smaller pixel size, such as a display device smaller than or equal to 0.3 inches, still can achieve higher resolution, thereby improving image quality.

It should be noted that the crescent lens refers to the spherical centers of its two refraction surfaces (the first side refraction surface and the second side refraction surface) are both on the left side of the corresponding surface or both are on the right side of the corresponding surface, that is, the two refraction surfaces are both. Concave on the same side; biconvex lens means the sphere center of its first refraction surface is on the right side of the surface, and the sphere center of the second refraction surface is on the left side of the surface; biconcave lens means the sphere center of its first refraction surface is on the On the left side of the surface, the center of the second refractive surface is on the right side of the surface. When the lens surface is flat, the relative position of the sphere center relative to the surface is positive infinity or negative infinity by default, which is classified in the lens shape. An aspherical lens means that both the first refractive surface and the second refractive surface of the lens are aspherical.

Specifically, the focal lengths of each lens group can be combined in various ways. In a preferred embodiment, the above-mentioned lens also satisfies the following parameter conditions:

1.47≤f' _A /f'≤2.44,

1.148≤f' _B /f'≤2.452,

-1.21≤f' _C /f'≤-0.80,

Wherein, f' _A , f' _B , and f' _C are the focal lengths of the first mirror group, the second mirror group, and the third mirror group, respectively, and the unit is mm.

By setting the above parameter ranges, each lens group can be better matched, thereby improving the imaging quality of the entire lens, reducing its throw ratio, and better adapting to the development of small display devices.

In the first lens group A, the four lenses can be arranged at intervals (meaning that there is a gap between the two lenses), or two or three of them can be attached together. The present invention considers the second lens L2, Both the third lens L3 and the fourth lens L4 are spherical lenses, therefore, in a preferred embodiment, the second lens L2, the third lens L3 and the fourth lens L4 in the first lens group A are laminated in sequence to form A triplet lens; the triplet lens is spaced apart from the first lens L1. In this embodiment, the triplet lens is combined with the first lens L1 so that the focal length of the entire first lens group A is positive. By gluing the three lenses in the first lens group A, the axial dimension of the first lens group A is significantly shortened, which is beneficial to the miniaturized design of the entire lens 4; It can effectively reduce the vertical axis chromatic aberration and better improve the color consistency of imaging. At the same time, since the triplet lens directly forms a whole, in the assembly of the entire lens 4, there is no need to adjust the relative positions of the second lens L2, the third lens L3 and the fourth lens L4. The assembly error between the lenses facilitates the stability of the assembly of the lens 4, reduces the impact of assembly tolerances on the resolution of the lens, saves assembly processes, improves the assembly efficiency of the lens, and is beneficial to the improvement of the lens yield in actual production.

The material of the third lens L3 is different from that of the second lens L2 and the fourth lens L4. Specifically, the refractive index of the second lens L2 and the refractive index of the fourth lens L4 are both greater than the refractive index of the third lens L3. Both the Abbe number of the second lens L2 and the Abbe number of the fourth lens L4 are smaller than the Abbe number of the third lens L3. Preferably, the refractive index of the second lens L2 and the refractive index of the fourth lens L4 are both greater than 1.7, and the refractive index of the third lens L3 is less than 1.6; the Abbe number of the second lens L2 is less than 45, and the Abbe number of the third lens L3 If the number is greater than 70, the Abbe number of the fourth lens L4 is less than 40. Through the above settings, the difference between the second lens L2, the fourth lens L4 and the third lens L3 is increased, thereby reducing the dispersion of the triplet lens and further optimizing The vertical axis chromatic aberration of lens 4 avoids the phenomenon of color fringing of the picture and optimizes the actual display effect. Specifically, through the above optimized settings, the vertical axis chromatic aberration of the present invention can reach less than half a pixel.

In the above triplet lens, the focal length of each lens satisfies: -0.15≤f ₂ '/f _{cemented'≤0.05} , -0.05≤f ₃ '/f _{cemented'≤0.15} , -0.2≤f ₄ '/f _{cemented'≤0.05} , 0.6≤f ₂ '/f ₄ '≤1.7. By setting the above parameters, the imaging effect of the triplet lens can be better improved. Wherein, the unit of _fgluing ' is mm.

In order to achieve better optimization of the entire lens, the focal length of the first lens L1 is positive, and the first lens group A also satisfies: 0.95≤f ₁ '/f' _A ≤1.3, -102≤f _glued '/f' _A ≤ 10.65.

The thickness of each lens in the above triplet lens and the parameters of the first refraction surface and the second refraction surface can be set according to the above parameters. In order to further reduce the axial dimension of the first lens group A and optimize the Image quality, the first mirror group A also satisfies:

The center thickness T of the triplet lens satisfies: _{0.815≤T cement} /f'≤1.278;

The central thickness T1 of the first lens L1 satisfies: 0.443≤T1/f'≤0.563;

The axial distance D1 between the first lens L1 and the triplet lens satisfies: 0.014≤D1/f'≤0.023.

In an embodiment, the first mirror group A also satisfies:

The radii R ₁₁ and R ₁₂ of the first refracting surface and the second refracting surface in the first lens L1 satisfy: 1.455≤R ₁₁ /f'≤2.44, -11.759≤R ₁₂ /f'≤-3.394;

The radii R ₂₁ and R ₂₂ of the first refracting surface and the second refracting surface in the second lens L2 satisfy: 1.245≤R ₂₁ /f'≤2.412, 0.759≤R ₂₂ /f'≤1.021;

The radii R ₃₁ and R ₃₂ of the first refracting surface and the second refracting surface in the third lens L3 satisfy: 0.759≤R ₃₁ /f'≤1.021, -1.884≤R ₃₂ /f'≤-1.379;

The radii R ₄₁ and R ₄₂ of the first refractive surface and the second refractive surface in the fourth lens L4 satisfy: -1.884≤R ₄₁ /f'≤-1.379, -17.895≤R ₄₂ /f'≤-5.004.

Through the above arrangement, the size of the first lens group A can be better reduced, and the imaging quality of the lens 4 can be improved. Notably, in the triplet embodiment, R ₂₂ is equal to R ₃₁ , and R ₃₂ is equal to R ₄₁ . In the remaining embodiments, R ₂₂ and R ₃₁ do not necessarily have to be equal, and R ₃₂ and R ₄₁ do not necessarily have to be equal.

In the embodiment in which the lenses in the first lens group A are arranged at intervals, the focal lengths of the lenses are preferably: 1.781≤f ₁ '/f'≤2.495, -3.219≤f ₂ '/f'≤-2.244, 1.12≤f ₃ '/f'≤1.457, -3.489≤f ₄ '/f'≤-1.935, so as to improve the imaging quality of the entire lens 4.

In the second lens group B, only one spherical convex lens is provided, and the fifth lens L5 is preferably set with the following parameters:

The refractive index is greater than 1.55, and the Abbe coefficient is less than 40;

The central thickness T5 of the fifth lens L5 satisfies: 0.308≤T5/f'≤0.654;

The radii R ₅₁ and R ₅₂ of the first refracting surface and the second refracting surface in the fifth lens L5 satisfy: 1.748≤R ₅₁ /f'≤3.555, -3.513≤R ₅₂ /f'≤-2.146.

By adopting the above parameter settings, the volume of the entire lens 4 can be further reduced, and the imaging quality of the lens 4 can be improved at the same time.

In the third lens group C, each lens satisfies: 1.85≤f ₆ '/f' _C ≤2.4, 2.2≤f ₇ '/f' _C ≤2.5; with respect to the entire lens 4, f ₆ ', f ₇ Satisfaction: -2.484≤f ₆ '/f'≤-1.544, -2.718≤f ₇ '/f'≤-1.94. In this way, the imaging quality of the third mirror group C can be further optimized.

Preferably, 0.75≤f ₆ '/f ₇ '≤1.05, the on-axis distance D6 between the sixth lens L6 and the seventh lens L7 satisfies: 0.414≤D6/f'≤0.818, so as to reduce the axis of the third lens group C The size of the entire lens 4 is made smaller, so as to better meet the imaging requirements of the small display device 1 .

Further, among the lenses of the third lens group C, the central thickness T6 of the sixth lens L6 satisfies: 0.142≤T6/f'≤0.316, and the central thickness T7 of the seventh lens L7 satisfies: 0.181≤T7/f'≤0.261 , to further optimize the third mirror group C to make it smaller in axial size.

In the third lens group C, the radii R ₆₁ and R ₆₂ of the first refractive surface and the second refractive surface in the sixth lens L6 satisfy: -1.541≤R ₆₁ /f'≤-1.192, R ₆₂ /f'≤- 4.965 or R ₆₂ /f'≥1.918; the radii R ₇₁ and R ₇₂ of the first refractive surface and the second refractive surface in the seventh lens L7 satisfy: -0.653≤R ₇₁ /f'≤-0.343, -1.395≤R ₇₂ /f'≤-0.636. In order to further optimize the lenses of the third lens group C, the imaging quality of the entire lens 4 is improved; and the volume of the entire third lens group C is better reduced to adapt to the development of small equipment.

No matter which of the above-mentioned embodiments is adopted, the respective first and second refractive surfaces of the first lens L1 and the seventh lens L7 satisfy:

Among them, for the convenience of expression, since the first refraction surface and the second refraction surface of the first lens L1 and the seventh lens L7 are both aspherical, the following is a unified expression for each refraction surface of the two as aspherical, and the aspherical surface The vertex refers to the intersection of the aspheric surface and the optical axis, then, Z represents the distance between the point on the aspheric surface and the vertex of the aspheric surface in the direction of the optical axis; r represents the distance from the point on the aspheric surface to the optical axis; c represents the distance of the aspheric surface Center curvature; k represents conic rate; a4, a6, a8, a10, a12, a14, a16 represent aspheric high-order coefficients.

Through the above arrangement, the refracting surfaces of the first lens L1 and the seventh lens L7 are controllable, so as to facilitate the adjustment of various parameters in the entire lens 4, so that the entire lens 4 has a smaller F number, projection ratio, and vertical axis chromatic aberration. , and higher resolution to achieve better image quality.

The specific position of the diaphragm S can be adjusted. In the preferred embodiment of the present invention, the diaphragm S is closer to the second mirror group B than the first mirror group A. Preferably, the distance between the first mirror group A and the diaphragm S is The on-axis distance D4 satisfies: 0.575≤D4/f'≤1.152; the on-axis distance DS between the diaphragm S and the second mirror group B satisfies: 0.371 ≤DS/f'≤0.594; to limit the beam and image size on the second side , so that the image formed by the lens 4 is clearer and more accurate, and the brightness of the image is improved.

In order to further improve the imaging effect, the on-axis distance D5 between the second mirror group B and the third mirror group C satisfies: 0.098≤D5/f'≤1.035.

Refer to Table 1 for the main parameters of each lens in the preferred embodiment of the present invention.

Table 1

When the above lens is used in an imaging system, the distance D0 between the first lens group A and the beam splitting device 3 on the optical axis is not limited in size, as long as the interference between the lens and other devices can be avoided. Under the same design conditions, this value The larger the size, the greater the design difficulty. Therefore, for the various embodiments in this paper, preferably, D0 is 0.1mm to 10mm, such as 4.781mm. In practical applications, this value can be changed according to actual needs; the third lens group The distance D7 between C and the image plane 5 (if applied to a projection device, it is the projection plane) on the optical axis satisfies: 117.647≤D7/f'≤181.818, wherein the units of D0 and D7 are mm. And the distance between the display device 1 and the protective glass 2 on the optical axis is 0.303mm. Of course, the distance is not limited to this, and can be determined according to the specific selected display device 1; the distance between the protective glass 2 and the spectroscopic device 3 on the optical axis is The distance is greater than 0.1mm, preferably 0.297mm. This value can be adjusted according to the actual design situation to avoid interference between the display device 1 and the scenery device 3 and the lens. By setting the above parameters, the projection ratio of the entire imaging system can be made smaller, the size of the entire imaging system can be further reduced, and the trend of miniaturization and miniaturization of electronic equipment can be adapted.

It is worth noting that the parameters of the above-mentioned lenses are not necessarily limited to the parameter combination limited by each embodiment, the parameter range of each lens can be combined in various ways, and the specific value of each parameter can be appropriately selected to achieve the overall zooming of the lens. Then it can adapt to more occasions. In addition, when the lens is zoomed, its focal length f' also changes accordingly, so that it can adapt to different focal length occasions, and can be adapted to different DMDs, such as 0.3 inch DMD and 0.47 inch DMD etc.

The design of the specific embodiment of the imaging system of the present invention is listed below by taking the display device 1 as a DMD and the light splitting device 3 as a prism. Among them, the parameters in the following tables are consistent with those in Table 1, and the interval in the display device 1, the protective glass 2 and the prism all refers to the distance between the optical component and the adjacent component located on one side of the positive direction on the optical axis. distance. Li-Sj refers to the j-th refractive surface of the i-th lens.

Referring to FIG. 3, it is a specific embodiment 1 of the imaging system, wherein the parameters of each lens, diaphragm and each optical device in the imaging system are shown in Table 2; wherein, the parameters of each aspherical surface of the first lens L1 and the seventh lens L7 See Table 3.

Table 2

table 3

The optical system parameters of the imaging system formed according to the parameters in Tables 2 and 3 are shown in Table 4.

Table 4

parameter unit Numerical value Remark Half field of view FOV ° 35.57 - Focal length f' mm 5.5 - Object Numerical Aperture NA 0.257 - telecentricity ° <1.05 MTF % >55% Spatial frequency 93lp/mm distortion % <0.81% Vertical chromatic aberration μm ≤2.7 Half pixel size 2.7μm

Referring to FIG. 4, it is a specific embodiment 2 of the imaging system, wherein the parameters of each lens, diaphragm and each optical device in the imaging system are shown in Table 5; wherein, the parameters of each aspherical surface of the first lens L1 and the seventh lens L7 See Table 6.

table 5

Table 6

The optical system parameters of the imaging system formed according to the parameters in Tables 5 and 6 are shown in Table 7.

Table 7

Referring to FIG. 5, it is the specific embodiment 3 of the imaging system, wherein the parameters of each lens, diaphragm and each optical device in the imaging system are shown in Table 8; wherein, the parameters of each aspherical surface of the first lens L1 and the seventh lens L7 See Table 9.

Table 8

Table 9

The optical system parameters of the imaging system formed according to the parameters in Tables 8 and 9 are shown in Table 10.

Table 10

parameter unit Numerical value Remark Half field of view FOV ° 24.82 - Focal length f' mm 8.5 - Object Numerical Aperture NA 0.292 - telecentricity ° <1 MTF % >49% Spatial frequency 93lp/mm distortion % <0.7% Vertical chromatic aberration μm ≤2.1 Half pixel size 2.7μm

Among them, in Table 4, Table 7, and Table 10, the Chinese meaning of MTF is modulation transfer function, which is a relatively scientific method for analyzing the imaging of lens. The range of MTF value is from 0 to 1; the unit of spatial frequency is line pair / In millimeters (lp/mm), the adjacent black and white lines can be called a line pair. The number of line pairs that can be distinguished per millimeter is the spatial frequency. Under the known spatial frequency, the closer the MTF value is to 1, the better the lens is. The better the resolution; distortion refers to the degree of distortion of the image formed by the optical system on the object relative to the object itself.

It can be seen from Table 4, Table 7 and Table 10 that when the display device 1 adopts a 0.3-inch DMD device, the lens 4 of the present invention is used, so that the entire imaging system has a larger field of view and a smaller projection. ratio, and the imaging is clear, the MTF can be greater than 49%, and the spatial frequency can reach 93lp/mm. At the same time, the distortion is less than 0.81%, and the vertical axis chromatic aberration is less than or equal to half a pixel. High quality. It can be seen that the lens has small distortion, high imaging quality, and uses a small number of optical parts, which can adapt to the application requirements of small display devices and high resolution, and is conducive to the development of electronic equipment towards miniaturization and miniaturization.

Those skilled in the art can understand that, under the premise of no conflict, the above preferred solutions can be freely combined and superimposed.

It should be understood that the above-mentioned embodiments are only exemplary rather than restrictive, and those skilled in the art can make various obvious or equivalent to the above-mentioned details without departing from the basic principles of the present invention. Modifications or replacements will be included within the scope of the claims of the present invention.

Claims (16)

1. A lens having a first side and a second side along an optical axis direction, wherein the lens comprises a first side and a second side sequentially arranged along the optical axis from the first side to the second side lens, second lens, third lens, fourth lens, fifth lens, sixth lens and seventh lens, the first lens, the second lens, the third lens and the fourth lens constitute The first mirror group, the fifth lens constitutes the second mirror group, the sixth lens and the seventh lens constitute the third mirror group, and the focal lengths of the first mirror group and the second mirror group are positive , the focal length of the third mirror group is negative, and a diaphragm is arranged between the first mirror group and the second mirror group; The second to sixth lenses are spherical glass lenses, and the first lens and the seventh lens are aspherical glass lenses; The first lens is a biconvex positive lens; the second lens is a crescent negative lens with both the first and second refracting surfaces concave to the second side; the third lens is a biconvex positive lens; the The fourth lens is a crescent negative lens with the first and second refracting surfaces both concave to the first side; the fifth lens is a double-convex positive lens; the sixth lens is a double-concave negative lens or the first and second lenses. The second refracting surface is concave to the first side of the crescent negative lens; the seventh lens is the crescent negative lens whose first and second refracting surfaces are both concave to the first side; wherein, the first refracting surface of each lens refers to It is the refracting surface close to the first side, and the second refracting surface refers to the refracting surface that is close to the second side; The lens satisfies the following parameter conditions: 24.8°≤FOV.≤35.6°, 0.250≤NA≤0.292, 5.5≤f'≤8.5; The refractive index of the first lens is less than 1.7, and the Abbe number is greater than 55; The refractive index of the seventh lens is greater than 1.5, and the Abbe number is greater than 50; Wherein: FOV. represents the image-side half-field angle of the lens, NA represents the object-side numerical aperture of the lens; f' is the focal length of the lens, in mm. 2. The lens according to claim 1, wherein the lens satisfies the following parameter conditions: 1.47≤f' _A /f'≤2.44, 1.148≤f' _B /f'≤2.452, -1.21≤f' _C /f'≤-0.80, Wherein, f' _A , f' _B , and f' _C are the focal lengths of the first mirror group, the second mirror group, and the third mirror group, respectively, and the unit is mm. 3 . The lens according to claim 2 , wherein the second lens, the third lens and the fourth lens are laminated in sequence to form a triplet lens; the focal length of the triplet lens is negative. 4 . ; The refractive index of the second lens and the refractive index of the fourth lens are both greater than 1.7, and the refractive index of the third lens is less than 1.6; The Abbe number of the second lens is less than 45, the Abbe number of the third lens is greater than 70, and the Abbe number of the fourth lens is less than 40. 4. The lens according to claim 3, wherein the first lens group also satisfies: 0.95≤f ₁ '/f' _A ≤1.3, -102≤f _glued '/f' _A≤10.65 , Wherein, f ₁ ′ and f _cemented are respectively the focal lengths of the first lens and the triplet lens, and the unit is mm. 5. The lens according to claim 4, wherein the triplet satisfies: -0.15≤f ₂ '/f _{glued'≤0.05} , _-0.05≤f3 '/ _{fglued'≤0.15} , -0.2≤f ₄ '/f _{glued'≤0.05} , 0.6≤f ₂ '/f ₄ '≤1.7; Wherein, f ₂ ′, f ₃ ′, and f ₄ ′ are the focal lengths of the second lens, the third lens, and the fourth lens, respectively, and the unit is mm. 6. The lens according to claim 4, wherein the first lens group also satisfies: The center thickness T of the triplet lens satisfies: _{0.815≤T cement} /f'≤1.278; The central thickness T1 of the first lens satisfies: 0.443≤T1/f'≤0.563; The axial distance D1 between the first lens and the triplet lens satisfies: 0.014≤D1/f'≤0.023; Among them, the unit of T _glue , T1, D1 is mm. 7. The lens according to claim 4, wherein the first lens group also satisfies: The radii R ₁₁ and R ₁₂ of the first refracting surface and the second refracting surface in the first lens satisfy: 1.455≤R ₁₁ /f'≤2.44, -11.759≤R ₁₂ /f'≤-3.394; The radii R ₂₁ and R ₂₂ of the first refracting surface and the second refracting surface in the second lens satisfy: 1.245≤R ₂₁ /f'≤2.412, 0.759≤R ₂₂ /f'≤1.021; The radii R ₃₁ and R ₃₂ of the first refracting surface and the second refracting surface in the third lens satisfy: 0.759≤R ₃₁ /f'≤1.021, -1.884≤R ₃₂ /f'≤-1.379; The radii R ₄₁ and R ₄₂ of the first refracting surface and the second refracting surface in the fourth lens satisfy: -1.884≤R ₄₁ /f'≤-1.379, -17.895≤R ₄₂ /f'≤-5.004; The units of R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₃₂ , R ₄₁ , and R ₄₂ are all mm. 8. The lens according to claim 2, wherein the refractive index of the fifth lens is greater than 1.55, and the Abbe coefficient is less than 40; The central thickness T5 of the fifth lens satisfies: 0.308≤T5/f'≤0.654; The radii R51 and R52 of the first refracting surface and the second refracting surface in the fifth lens satisfy: 1.748≤R ₅₁ /f'≤3.555, -3.513≤R ₅₂ /f'≤-2.146; The units of T5, R ₅₁ , and R ₅₂ are mm. 9. The lens according to claim 2, wherein the third lens group satisfies: 1.85≤f ₆ '/f' _C ≤2.4, 2.2≤f ₇ '/f' _C ≤2.5; Wherein, f ₆ ′ and f ₇ ′ are the focal lengths of the sixth lens and the seventh lens, respectively, and the unit is mm. 10. The lens according to claim 2, wherein the third lens group satisfies: 0.75≤f ₆ '/f ₇ '≤1.05; The axial distance D6 between the sixth lens and the seventh lens satisfies: 0.414≤D6/f'≤0.818; Wherein, f ₆ ′ and f ₇ ′ are the focal lengths of the sixth lens and the seventh lens, respectively, and the units of f ₆ ′, f ₇ ′, and D6 are all mm. 11. The lens of claim 2, wherein: The radii R61 and R62 of the first refractive surface and the second refractive surface in the sixth lens satisfy: -1.541≤R61/ _f'≤ -1.192, _R62 /f'≤-4.965 or _R62 /f'≥1.918 ; The radii R71 and R72 of the first refracting surface and the second refracting surface in the seventh lens satisfy: -0.653≤R71/ _f'≤ -0.343, _-1.395≤R72 /f'≤-0.636; The units of R ₆₁ , R ₆₂ , R ₇₁ , and R ₇ are all mm. 12. The lens according to any one of claims 1-11, wherein the first and second refractive surfaces of the first lens and the seventh lens both satisfy:

Among them, Z represents the distance from the point on the aspheric surface to the vertex of the aspheric surface in the direction of the optical axis; r represents the distance from the point on the aspheric surface to the optical axis; c represents the central curvature of the aspheric surface; k represents the conic rate; a4, a6, a8, a10, a12, a14, and a16 represent aspherical high-order coefficients. 13. The lens according to any one of claims 1-11, characterized in that, The axial distance D4 between the first mirror group and the diaphragm satisfies: 0.575≤D4/f'≤1.152; The axial distance DS between the diaphragm and the second mirror group satisfies: 0.371≤DS/f'≤0.594; The axial distance D5 between the second mirror group and the third mirror group satisfies: 0.098≤D5/f'≤1.035; The units of D4, DS, and D5 are all mm. 14. An imaging system, characterized in that it comprises a display device, a light-splitting device and the lens according to any one of claims 1-13 arranged in sequence, and the display device and the light-splitting device are all located in the The first side of the lens. 15. The imaging system according to claim 14, wherein the display device comprises a DMD, LCOS or LCD display device; and the size of the display device is less than or equal to 0.3 inches. 16. An electronic device, characterized by comprising the imaging system according to claim 14 or 15.

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