CN212181146U

CN212181146U - Miniature lens

Info

Publication number: CN212181146U
Application number: CN202020981383.6U
Authority: CN
Inventors: 孙旭科; 赵鸿明; 孙仲辉
Original assignee: Ningbo Jinhui Optical Technology Co ltd
Current assignee: Ningbo Jinhui Optical Technology Co ltd
Priority date: 2020-06-02
Filing date: 2020-06-02
Publication date: 2020-12-18
Anticipated expiration: 2030-06-02

Abstract

The utility model discloses a miniature lens, which comprises a lens group, wherein the lens group sequentially comprises a first lens, a second lens, a third lens and a fourth lens from an object side to an image side, the first lens has negative focal power, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface; the second lens has positive focal power; the object side surface is convex, and the image side surface is convex; the third lens has positive focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the fourth lens has positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; the diagonal field angle range of the lens group is satisfied: FOV-D is more than or equal to 137 degrees and less than or equal to 152 degrees, and the lens group meets the conditional expression: the (R1+ R2)/(R1-R2) is more than or equal to 0.34 and less than or equal to 2.5, wherein R1 is the curvature radius of the first lens, R2 is the curvature radius of the second lens, the miniature lens is miniaturized and portable, has high-quality imaging effect at the same time, and is suitable for various products with portable requirements.

Description

Miniature lens

Technical Field

The utility model relates to an optical lens technical field, concretely relates to miniature camera lens.

Background

Along with the requirement of portability of optical lenses, the field of digital images is continuously innovated and changed, the micro-lens not only needs a small volume, but also needs high-quality imaging, at present, most of the micro-lenses in the market are composed of at least 4 optical lenses, each lens has different structural designs, and the micro-lens in the prior art is usually in a mode of adding lenses in order to improve the field angle of the lens to be larger than 90 degrees, so that the light path is easily diverged in a lens group, distortion and aberration are caused, the imaging effect is influenced, and in order to make up for the imaging problem, the whole volume of the lens is increased, and the miniaturization requirement of the lens is opposite to the miniaturization requirement of the lens.

SUMMERY OF THE UTILITY MODEL

Not enough to prior art exists, the utility model aims to provide a miniature camera lens reduces whole volume and guarantees the imaging effect.

The above technical purpose of the present invention can be achieved by the following technical solutions: a miniature lens, its characterized in that: comprises a lens group, the lens group comprises a first lens, a second lens, a third lens and a fourth lens from an object side to an image side in sequence,

the first lens has negative focal power, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface;

the second lens has positive optical power; the object side surface is convex, and the image side surface is convex;

the third lens has positive focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface;

the fourth lens has positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface;

the diagonal field angle range of the lens group satisfies the following conditions: FOV-D is more than or equal to 137 degrees and less than or equal to 152 degrees, and the lens group satisfies the conditional expression: 0.34-2.5 of (R1+ R2)/(R1-R2), wherein R1 is the curvature radius of the first lens, and R2 is the curvature radius of the second lens.

Furthermore, the first lens, the second lens and the third lens are all made of optical plastic materials.

Further, the first lens, the second lens and the third lens may be disposed adjacent to each other in sequence, and the fourth lens may be disposed at an interval from the third lens.

Further, the second lens and the fourth lens are both aspheric lenses.

Further, the lens group also comprises a horizontal angle of view FOV-H and a vertical angle of view FOV-V, and satisfies: the FOV-H is more than or equal to 99 degrees and less than or equal to 109 degrees, and the FOV-V is more than or equal to 70 degrees and less than or equal to 78 degrees.

Further, the lens group further satisfies the conditional expression: 1.02 ≦ R7/R8 ≦ 1.8, where R7 is the radius of curvature of the object-side surface of the fourth lens and R8 is the radius of curvature of the image-side surface of the fourth lens.

Further, the lens group further satisfies the conditional expression: 1.49 ≦ R4/R3 ≦ 1.52, where R3 is the radius of curvature of the object-side surface of the second lens and R4 is the radius of curvature of the image-side surface of the second lens.

Further, the lens group further satisfies the conditional expression: 15.2 ≦ (R1+ CT1)/R2 ≦ 22, wherein R1 is the radius of curvature of the object-side surface of the first lens; r2 is the radius of curvature of the image-side surface of the first lens; CT1 is the center thickness of the first lens in the optical axis direction.

Further, the light-shielding mylar sheet has a predetermined aperture; the light guide device is characterized in that an acute angle light guide angle is arranged on the light through hole of the first space ring, an obtuse angle light guide angle is arranged on the light through hole of the second space ring, and the upper molding surface of the acute angle light guide angle and the upper molding surface of the obtuse angle light guide angle are larger than the lower molding surface so that light is converged towards the injection direction and is diffused towards the injection direction.

Further, the optical back focal length BFL of the miniature lens and the optical total length TTL of the miniature lens meet the following requirements: BFL/TTL is more than or equal to 0.21 and less than or equal to 0.25.

Further, the focal length value F1 of the third lens and the focal length value F2 of the fourth lens satisfy that: F2/F1 of which the ratio is more than or equal to 5.15 and less than or equal to 5.75.

Further, the lens group further comprises a space ring and an optical filter, a cavity for accommodating the lens group is formed in the lens frame, the optical filter is arranged at the end portion, close to an imaging surface, of the lens frame, the space ring is erected on the inner wall of the lens frame, and a mounting seat for erecting a third lens is arranged at one end, close to the object side, of the space ring.

Furthermore, a first light guide angle for guiding light from the third lens and a light guide surface for limiting the light to enter the effective area of the fourth lens are sequentially arranged on the mounting seat close to the image side, and a second light guide angle for guiding the light to cover the optical filter is arranged on the spectacle frame.

Compared with the prior art, the utility model has the advantages of it is following and beneficial effect: compared with the existing miniature lens, the utility model provides a miniature lens is at the during operation, the light path is at first dispersed through the object side of first lens and is restrainted, through the second lens alignment and level and smooth light path, restraint to minimum light path through the cooperation of first light guide angle on third lens and the spacer ring, the cooperation of leaded light face and fourth lens is enlargied again and is dispersed and pass through the light filter to the imaging surface on the spacer ring, realize miniature lens's portable and miniaturized function, the imaging effect that has the high quality simultaneously, be applicable to various products that have portable requirement.

Drawings

Fig. 1 is a schematic structural view of a lens group, a lens holder and an image plane according to the present invention;

fig. 2 is a schematic view of the mirror holder, spacer ring and optical filter of the present invention;

FIG. 3 is a light path diagram of the lens assembly of the present invention;

FIG. 4 is a MTF chart of the present invention

Fig. 5 is a relative illuminance diagram of the present invention;

in the figure: 1. a frame; 1.1, a second light guide angle; 2. a first lens; 3. a second lens; 4. a third lens; 5. a fourth lens; 6. a space ring; 6.1, mounting seats; 6.2, a first light guide angle; 6.3, a light guide surface; 7. an optical filter;

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

It will be understood that, although the terms upper, middle, lower, top, end, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another for ease of understanding, and are not used to define any direction or order of limitation.

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. It should be understood that the surface of each lens near the image source side is referred to as the object side surface, and the surface of each lens near the image forming side is referred to as the image side surface.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

A miniature lens comprises a lens group and a lens frame 1, wherein an installation cavity for installing the lens group is arranged in the lens frame 1, the lens group comprises four lenses with focal power, namely a first lens 2, a second lens 3, a third lens 4 and a fourth lens 5, the three lenses are sequentially arranged from an imaging side to an image source side along an optical axis, and each lens is provided with an object side surface facing to an object side and enabling imaging light to pass through and an image side surface facing to the image side and enabling the imaging light to pass through.

The first lens element 2 has negative focal power, the object-side surface S1 of the first lens element is a concave surface, i.e., a concave surface facing the image source side and a curved surface close to a plane, so that the optical path converges towards the image-side surface S2 in a wide field angle range, the image-side surface S2 of the first lens element is a convex surface, i.e., an arc protruding towards the object side, the light converged by the object-side surface S1 is converged and dispersed onto the object-side surface S3 of the second lens element 3, the first lens element 2 is made of an optical glass material S-LAL61, and the refractive index of the first: nd1 is more than or equal to 1.741, and the first lens 2 is a spherical lens;

and plating first reflecting films on the object side surface and the image side surface of the first lens 2 to reduce the reflectivity and improve the transmittance, wherein when the wavelength of visible light is 400-430 nm, the absolute reflectivity Rabs meets the following requirements: rabs is less than 1 percent; when the wavelength of visible light is 430-650 nm, the average reflectivity Ravg meets the following requirements: ravg is less than 0.5%, and the absolute reflectivity Rabs meets the following conditions: rabs is less than 0.8 percent; when the wavelength of visible light is 650-700 nm, the absolute reflectivity Rabs meets the following requirements: rabs is less than 1.5 percent;

the second lens 3 has positive optical power; the object side surface S3 is a convex surface, the image side surface S4 is a convex surface, the object side surface S3 and the image side surface S4 are both in a meniscus shape protruding towards the image source side, the convexity of the object side surface S3 and the convexity of the image side surface S4 on the optical axis are close, namely, the object side surface S4 and the image side surface S4 are close to the shape of a concentric circle, the second lens 3 has larger thickness, so that the optical path is smoothly performed, the effective diameter of the object side surface S3 is larger than that of the image side surface S4, so that the optical path is converged towards the third lens 4, the propagation effect is met, the second lens 3 is made of an optical plastic material OKP 1: nd1 is more than or equal to 1.642, and the second lens 3 is an aspheric lens;

and plating second reflecting films on the object side surface and the image side surface of the second lens 3 to reduce the reflectivity and improve the transmittance, wherein when the wavelength of visible light is 420-680 nm, the average reflectivity meets the following requirements: ravg is less than or equal to 0.8 percent.

The third lens 4 has positive focal power, the object side surface S5 is a convex surface, the image side surface S6 is a concave surface, the curvature radius of the image side surface S6 is larger than that of the object side surface S5, so that the light path passing through the image side surface S6 is close to the first light guide angle 6.2 of the spacer 6, the light guide effect is better, the use requirement of the micro optical lens is met, the third lens 4 is made of optical glass material S-LAL61, and the refractive index of the third lens is satisfied: the Nd1 is more than or equal to 1.741, and the third lens 4 is a spherical lens.

And third reflecting films are plated on the object side surface and the image side surface of the third lens 4 to reduce the reflectivity and improve the transmittance, and when the wavelength of visible light is 420-680 nm, the average reflectivity meets the following requirements: ravg is less than or equal to 0.8 percent.

The fourth lens 5 has positive power, the object-side surface S7 is a concave surface, the image-side surface S8 is a concave surface, and the image-side surface S6 has a tendency to move further toward the image side relative to the object-side surface S5, so that the light passing through the image-side surface S5 passes through the image-side surface S6 and is more gentle and tangential to the second light guiding angle 1.1, thereby the light path covers a larger area on the optical filter 7, the fourth lens 5 is made of an optical plastic material 480R, and the refractive index of the optical plastic material is satisfied: nd1 is equal to or more than 1.531, and the fourth lens 5 is an aspheric lens.

And fourth reflecting films are plated on the object side surface and the image side surface of the fourth lens 5 to reduce the reflectivity and improve the transmittance, and when the wavelength of visible light is 420-680 nm, the average reflectivity meets the following requirements: ravg is less than or equal to 0.8 percent.

The lens group further comprises a space ring 6 and a light filter 7, a cavity for accommodating the lens group is arranged in the lens frame 1, the light filter 7 is arranged at the end part, close to an imaging surface, of the lens frame 1, the space ring 6 is erected on the inner wall of the lens frame 1, a mounting seat 6.1 for erecting the third lens 4 is arranged at one end, close to the object side, of the space ring 6, a first light guide angle 6.2 for guiding light rays from the third lens 4 and a light guide surface 6.3 for limiting the light rays to be emitted into an effective area of the fourth lens 5 are sequentially arranged at the position, close to the imaging side, of the mounting frame 1, a second light guide angle 1.1 for guiding the light rays to cover the light filter 7 is arranged at one end, close to the imaging side, stray light is eliminated by the space ring 6 to a certain degree, and the light guide surface 6.3, the first light guide angle 6.2 and the second light guide angle.

In summary, the lens assembly has a first region for collecting light path and a second region for emitting light path, wherein the first region is composed of the first lens 2, the second lens 3 and the third lens 4, and the second region is composed of the spacer 6, the fourth lens 5 and the optical filter 7.

And the micro optical lens satisfies the following parameters:

conditional formula (1): FOV-D is more than or equal to 137 degrees and less than or equal to 152 degrees, FOV-H is more than or equal to 99 degrees and less than or equal to 109 degrees, and FOV-V is more than or equal to 70 degrees and less than or equal to 78 degrees; FOV-H is horizontal field angle, FOV-V is vertical field angle, and FOV-D is diagonal field angle.

Conditional formula (2): BFL/TTL is more than or equal to 0.21 and less than or equal to 0.25, and the preferable range is between 0.221 and 0.246.

Conditional formula (3): D/H/FOV is more than or equal to 0.013 and less than or equal to 0.015, and the preferable range is between 0.0131 and 0.0145; wherein D is the maximum clear aperture of the object-side surface S1 of the first lens element 2 corresponding to the maximum field angle of the optical lens assembly; h is the image height corresponding to the maximum field angle of the optical lens group 2.

Conditional formula (4): TTL/EFL is less than or equal to 4.5, the preferred range is 4.32-4.41, TTL is the total optical length of the optical lens assembly, and EFL is the effective focal length of the optical lens assembly.

Conditional formula (5): TTL/H/FOV is more than or equal to 0.025 and less than or equal to 0.030, and the preferable range is between 0.026 and 0.027.

Conditional formula (6): 0.34-2.5 of (R1+ R2)/(R1-R2), wherein R1 is the curvature radius of the object side S1 of the first lens 2; r2 is the radius of curvature of the image-side surface S2 of the first lens element 2;

conditional formula (7): 15.2 is less than or equal to (R1+ CT1)/R2 is less than or equal to 22; wherein R1 is the radius of curvature of the object-side surface S1 of the first lens 2; r2 is the radius of curvature of the image-side surface S2 of the first lens element 2; CT1 is the central thickness of the first lens 2 on the optical axis.

Conditional formula (8): the absolute value of R6/R5 is more than or equal to 0.58 and less than or equal to 0.605; where R5 is a radius of curvature of the object-side surface S5 of the third lens 4, and R6 is a radius of curvature of the image-side surface S6 of the third lens 4.

Conditional formula (9): F2/F1 is not less than 5.15 and not more than 5.75, wherein F1 is the focal length value of the first lens 2, and F2 is the focal length value of the first lens 2.

Example one

As a first embodiment of the present invention, as shown in fig. 1-3, a micro lens includes a lens group and a lens holder 1, the lens holder 1 has a mounting cavity for placing the lens group, the lens group includes four lenses with refractive power, i.e. a first lens 2, a second lens 3, a third lens 4 and a fourth lens 5, the three lenses are sequentially arranged along an optical axis from an image side to an image source side, and each lens has an object side surface facing to the object side and passing the image light and an image side surface facing to the image side and passing the image light.

The first lens element 2 has negative power, the object-side surface S1 is concave, the image-side surface S2 is convex, and the first lens element 2 is a spherical lens element; the second lens 3 has positive optical power; the object-side surface S3 is a convex surface, the image-side surface S4 is a convex surface, and the second lens element 3 is an aspheric lens element; the third lens element 4 has positive power, the object-side surface S5 is a convex surface, the image-side surface S6 is a concave surface, and the third lens element 4 is a spherical lens element; the fourth lens element 5 has positive optical power, the object-side surface S7 is concave, the image-side surface S8 is concave, and the fourth lens element 5 is an aspherical lens element.

The lens group further comprises a space ring 6 and a light filter 7, the light filter 7 is arranged at the end part, close to an imaging surface, of the lens frame 1, the space ring 6 is erected on the inner wall of the lens frame 1, a mounting seat 6.1 for the third lens 4 to be erected is arranged at one end, close to the object side, of the space ring 6, a first light guide angle 6.2 for guiding light rays from the third lens 4 and a light guide surface 6.3 for limiting the light rays to be emitted into an effective area of the fourth lens 5 are sequentially arranged on the mounting seat 6.1, close to the imaging surface, of the lens frame 1, a second light guide angle 1.1 for guiding the light rays to cover the light filter 7 is arranged at one end, close to the imaging surface, the first light guide angle 6.2 is an acute angle converging towards the imaging side center, and the second light guide angle 1.1 is an acute angle far away from the.

Table 1 shows the curvature radius R, the thickness T, the gap G, the refractive index Nd, the abbe number Vd, the focal length F, and the material of the first lens element 2, the second lens element 3, the third lens element 4, and the fourth lens element 5 in the lens group, wherein the curvature radius R, the thickness T, the gap G, and the focal length F are all in millimeters (mm).

TABLE 1

The even-order aspheric rise formula for each mirror is defined as follows:

wherein Z is the distance rise from the aspheric surface fixed point when the aspheric surface is at the position with the height of h along the optical axis direction; c is paraxial curvature of the aspheric surface, and c is 1/R; k is a conic coefficient; r is the distance from a point on the optical surface to the optical axis; α 1, α 2, α 3, α 4, α 5, α 6, α 7, α 8 are all high-order coefficient.

Table 2 shows the conical coefficients k and the respective high-order term coefficients for the aspherical lens surfaces S3 to S4, S7 to S8 used in the present embodiment.

TABLE 2

Table 3 below shows an optical back focus BFL (i.e., an on-axis distance from the center of the image-side surface S8 of the fourth lens element 5 to the imaging surface IMA), a total length TTL of the lens assembly (i.e., an on-axis distance from the center of the object-side surface S1 of the first lens element 2 to the imaging surface IMA), a maximum aperture diameter D of the object-side surface S1 of the first lens element 2 corresponding to a maximum field angle of the lens assembly, an image height H corresponding to a maximum field angle of the optical lens, a diagonal field angle FOV-D of the optical lens, a horizontal field angle-H, a vertical field angle FOV-V, an effective focal length EFL of the optical lens assembly, and an optical focus FNO of the present embodiment.

TABLE 3

EFL(mm)	2.3	D(mm)	φ4.5
				BFL(mm)	2.35	FOV-D(°)	144°
TTL(mm)	10.05	FOV-H(°)	104°
				H(mm)	2.58	FOV-V(°)	74°
FNO	2.65

In this embodiment, the optical back focus BFL of the optical lens group and the total optical length TTL of the optical lens assembly satisfy the following conditional expression: BFL/TTL 0.2338; the maximum clear aperture D of the object-side surface S1 of the first lens 2 corresponding to the maximum field angle and the image height H corresponding to the maximum field angle satisfy D/H/FOV of 0.0121; the total optical length TTL and the effective focal length of the optical lens group satisfy the following conditional expression: TTL/EFL 4.3695; the total optical length TTL, the maximum field angle FOV of the optical lens and the image height H corresponding to the maximum field angle of the optical lens meet the condition that TTL/H/FOV is 0.027; the radius of curvature R1 of the object-side surface S1 of the first lens 2 and the radius of curvature R2 of the image-side surface S2 of the first lens 2 satisfy | (R1+ R2)/(R1-R2) | 0.088; the radius of curvature R3 of the object-side surface S5 of the third lens 4 and the radius of curvature R4 of the image-side surface S6 of the third lens 4 are all 0.605 from | R6/R5 |; the radii of curvature of the object-side surface S1 and the image-side surface S2 of the first lens 2 and CT1 satisfy the following relationship: (R1+ CT1)/R2| ═ 15.4546; the focal length value F1 of the first lens 2 and the focal length value F2 of the second lens 3 satisfy that: F2/F1 ═ 5.172;

example two

As a second embodiment of the present invention, a micro lens includes a lens group and a lens holder 1, the lens holder 1 has a mounting cavity for placing the lens group, the lens group includes four lenses with refractive power, i.e. a first lens 2, a second lens 3, a third lens 4 and a fourth lens 5, the three lenses are sequentially arranged along an optical axis from an image side to an image source side, and each lens has an object side surface facing an object side and an image side surface facing the image side and making the image side pass through.

Table 4 shows the curvature radius R, the thickness T, the gap G, the refractive index Nd, the abbe number Vd, the focal length F, and the material of the first lens element 2, the second lens element 3, the third lens element 4, and the fourth lens element 5 in the lens group, wherein the curvature radius R, the thickness T, the gap G, and the focal length F are all in millimeters (mm).

TABLE 4

The even-order aspheric rise formula for each mirror is defined as follows:

Table 5 shows the conic coefficients k and the respective high-order term coefficients for the aspherical lens surfaces S3 to S4, S7 to S8 used in the present embodiment.

TABLE 5

Table 6 below shows the optical back focus BFL (i.e. the on-axis distance from the center of the image-side surface S8 of the fourth lens element 5 to the imaging surface IMA), the total length TTL (i.e. the on-axis distance from the center of the object-side surface S1 of the first lens element 2 to the imaging surface IMA), the maximum aperture D of the object-side surface S1 of the first lens element 2 corresponding to the maximum field angle of the lens assembly, the image height H corresponding to the maximum field angle of the optical lens, the diagonal field angle FOV-D, the horizontal field angle-H, the vertical field angle FOV-V, the effective focal length EFL and the optical focus FNO of the optical lens group.

TABLE 6

EFL(mm)	2.3	D(mm)	φ4.5
				BFL(mm)	2.25	FOV-D(°)	144°
TTL(mm)	9.95	FOV-H(°)	104°
				H(mm)	2.58	FOV-V(°)	74°
FNO	2.52

In this embodiment, the optical back focus BFL of the optical lens group and the total optical length TTL of the optical lens assembly satisfy the following conditional expression: BFL/TTL 0.2261; the maximum light transmission aperture D of the object-side surface S1 of the first lens 2 corresponding to the maximum field angle and the image height H corresponding to the horizontal field angle satisfy D/H/FOV 0.1677; the total optical length TTL and the effective focal length of the optical lens group satisfy the following conditional expression: TTL/EFL 4.3261; the total optical length TTL, the maximum field angle FOV of the optical lens and the image height H corresponding to the maximum field angle of the optical lens satisfy that TTL/H/FOV is 0.02678; the radius of curvature R5 of the object-side surface S5 of the third lens 4 and the radius of curvature R6 of the image-side surface S6 of the third lens 4 meet the conditions of | R6/R5| -0.5817; the radius of curvature R1 of the object-side surface S1 of the first lens 2 and the radius of curvature R2 of the image-side surface S2 of the first lens 2 satisfy | (R1+ R2)/(R1-R2) | ═ 0.9134; the radii of curvature of the object-side surface S1 and the image-side surface S2 of the first lens 2 and CT1 satisfy the following relationship: (R1+ CT1)/R2 ═ -21.7954; the focal length value F1 of the first lens 2 and the focal length value F2 of the second lens 3 satisfy that: F2/F1 ═ -5.6761;

EXAMPLE III

As a third embodiment of the present invention, a micro lens includes a lens group and a lens holder 1, a mounting cavity for placing the lens group is provided in the lens holder 1, the lens group includes four lenses with refractive power, i.e. a first lens 2, a second lens 3, a third lens 4 and a fourth lens 5, the three lenses are sequentially arranged along an optical axis from an image side to an image source side, and each lens has an object side surface facing an object side and an image side surface facing the image side and allowing the image light to pass through.

Table 7 shows the radius of curvature R, the thickness T, the gap G, the refractive index Nd, the abbe number Vd, the focal length F, and the material of the first lens element 2, the second lens element 3, the third lens element 4, and the fourth lens element 5 in the lens group, wherein the unit of the radius of curvature R, the thickness T, the gap G, and the focal length F is millimeters (mm).

TABLE 7

The even-order aspheric rise formula for each mirror is defined as follows:

Table 8 shows the conical coefficients k and the respective high-order term coefficients for the aspherical lens surfaces S3 to S4, S7 to S8 used in the present embodiment.

TABLE 8

Table 9 below shows an optical back focus BFL (i.e., an on-axis distance from the center of the image-side surface S8 of the fourth lens element 5 to the imaging surface IMA), a total length TTL of the lens assembly (i.e., an on-axis distance from the center of the object-side surface S1 of the first lens element 2 to the imaging surface IMA), a maximum aperture diameter D of the object-side surface S1 of the first lens element 2 corresponding to a maximum field angle of the lens assembly, an image height H corresponding to a maximum field angle of the optical lens, a diagonal field angle FOV-D of the optical lens, a horizontal field angle-H, a vertical field angle FOV-V, an effective focal length EFL of the optical lens assembly, and an optical focus FNO of the present embodiment.

TABLE 9

In this embodiment, the optical back focus BFL of the optical lens group and the total optical length TTL of the optical lens assembly satisfy the following conditional expression: BFL/TTL 0.2413; the maximum light transmission aperture D of the object side surface S1 of the first lens 2 corresponding to the maximum field angle and the image height H corresponding to the maximum field angle satisfy that D/H/FOV is 0.0216; total track length TTL and optical lens set

The effective focal length satisfies the following conditional expression: TTL/EFL 4.413; the total optical length TTL, the maximum field angle FOV of the optical lens and the image height H corresponding to the maximum field angle of the optical lens meet the condition that TTL/H/FOV is 0.0273; the radius of curvature R1 of the object-side surface S1 of the first lens 2 and the radius of curvature R2 of the image-side surface S2 of the first lens 2 satisfy | (R1+ R2)/(R1-R2) | 1.675; the radius of curvature R5 of the object-side surface S5 of the third lens 4 and the radius of curvature R6 of the image-side surface S6 of the third lens 4 satisfy | R6/R5| — -0.6051; the radius of curvature R1 of the object-side surface S1 of the first lens 2 and the radius of curvature R2 of the image-side surface S2 of the first lens 2 satisfy | (R1+ R2)/(R1-R2) | ═ 0.8813; the radii of curvature of the object-side surface S1 and the image-side surface S2 of the first lens 2 and CT1 satisfy the following relationship: (R1+ CT1)/R2 ═ 15.548; the focal length value F1 of the first lens 2 and the focal length value F2 of the second lens 3 satisfy that: F2/F1 ═ 5.174;

fig. 3 is a graph of MTF (modulation optical transfer function) of the middle micro optical lens of the present invention, in which the abscissa represents spatial frequency, unit: wire pairs per millimeter (lp/mm); the ordinate represents the value of MTF (modulation optical transfer function), the value of MTF is used for evaluating the imaging clarity condition of the vehicle-mounted lens, the value range is 0-1, and the MTF curve represents the imaging clarity capability of the lens and the image restoration capability. As can be seen from fig. 3, the MTF curves in the meridional direction T and the sagittal direction S of each field are dense, which indicates that: the vehicle-mounted lens has good consistency on the whole imaging surface IMA, and can realize high-quality clear imaging on the whole imaging surface.

Fig. 4 is a relative illumination chart of the micro optical lens of the present invention. As can be seen from fig. 4, the relative illumination of more than 68% can be maintained in the full field of view, so that the overall illumination of the image plane is uniform, and the defect that some lenses on the market are dark at the periphery is avoided.

Known through above embodiment, compare with current micro lens, the utility model provides a micro lens is at the during operation, the first thing side S1 through first lens 2 that diverges of light path is restrainted, through the 3 alignment of second lens and level and smooth light path, through the cooperation of first leaded light angle 6.2 on third lens 4 and the spacer 6 is restrainted to minimum light path, the cooperation of leaded light face 6.3 and fourth lens 5 is enlargied again and is dispersed and pass through light filter 7 to the image plane on the spacer 6, realize that micro lens is miniaturized and portable, the imaging effect that has the high quality simultaneously, be applicable to various products that have portable requirement.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications to the present embodiment without inventive contribution as required after reading the present specification, but all of them are protected by patent laws within the scope of the claims of the present invention.

Claims

1. A miniature lens, its characterized in that: comprises a lens group which comprises a first lens (2), a second lens (3), a third lens (4) and a fourth lens (5) from an object side to an image side in sequence,

the first lens (2) has negative focal power, the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a convex surface;

the second lens (3) has a positive optical power; the object side surface is convex, and the image side surface is convex;

the third lens (4) has positive focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface;

the fourth lens (5) has positive focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface;

the field angles of the lens group comprise diagonal field angles, and the diagonal field angle range of the lens group satisfies: FOV-D is more than or equal to 137 degrees and less than or equal to 152 degrees, and the lens group satisfies the conditional expression: 0.34-2.5 of (R1+ R2)/(R1-R2), wherein R1 is the curvature radius of the first lens (2), and R2 is the curvature radius of the second lens (3).

2. A miniature lens as set forth in claim 1, wherein: the first lens (2), the second lens (3) and the third lens (4) can be arranged adjacent to each other in sequence, and the fourth lens (5) can be arranged at intervals with the third lens (4).

3. A miniature lens as set forth in claim 1, wherein: the second lens (3) and the fourth lens (5) are both aspheric lenses.

4. A miniature lens according to any one of claims 1 to 3, wherein: the lens group further comprises a horizontal field angle FOV-H and a vertical field angle FOV-V, and satisfies: the FOV-H is more than or equal to 99 degrees and less than or equal to 109 degrees, and the FOV-V is more than or equal to 70 degrees and less than or equal to 78 degrees.

5. A miniature lens according to any one of claims 1 to 3, wherein: the lens group further satisfies the conditional expression: 1.02 ≦ R7/R8 ≦ 1.8, where R7 is the radius of curvature of the object-side surface of the fourth lens (5), and R8 is the radius of curvature of the image-side surface of the fourth lens (5).

6. A miniature lens according to any one of claims 1 to 3, wherein: the lens group further satisfies the conditional expression: 15.2 is less than or equal to (R1+ CT1)/R2 is less than or equal to 22,

wherein R1 is the curvature radius of the object side surface of the first lens (2);

r2 is the radius of curvature of the image side surface of the first lens (2);

CT1 is the central thickness of the first lens (2) in the optical axis direction.

7. A miniature lens according to any one of claims 1 to 3, wherein: the optical back focal length BFL of the miniature lens and the optical total length TTL of the miniature lens meet the following requirements: BFL/TTL is more than or equal to 0.21 and less than or equal to 0.25.

8. A miniature lens according to any one of claims 1 to 3, wherein: the focal length value F1 of the first lens (2) and the focal length value F2 of the first lens (2) satisfy that: F2/F1 of which the ratio is more than or equal to 5.15 and less than or equal to 5.75.

9. A miniature lens according to any one of claims 1 to 3, wherein: the mirror group further comprises a space ring (6) and a mirror bracket (1), a cavity for accommodating the mirror group is arranged in the mirror bracket (1), the space ring (6) is erected on the inner wall of the mirror bracket (1), and a mounting seat (6.1) for erecting a third lens (4) is arranged at one end, close to the object side, of the space ring (6).

10. A miniature lens as set forth in claim 9, wherein: the mounting seat (6.1) is provided with a first light guide angle (6.2) used for guiding light rays from the third lens (4) and a light guide surface (6.3) used for limiting the light rays to enter an effective area of the fourth lens (5) in sequence close to the image side, and the spectacle frame (1) is provided with a second light guide angle (1.1) used for guiding the light rays to cover the optical filter (7).