CN104181676B - Microminiature lens - Google Patents

Abstract

The invention relates to a miniature lens, which sequentially includes a first lens, a second lens and a third lens along the optical axis from the object side to the image side. The first lens is a convex-concave lens with negative refractive power. The convex surface of the first lens faces the object side and the concave surface faces the image side. The second lens has positive refractive power. The third lens is a convex-concave lens with negative refractive power. The convex surface of the third lens faces the object side and the concave surface faces the image side.

Description

micro lens

technical field

The present invention relates to a lens, in particular to a miniature lens.

Background technique

Most of the currently known lenses with a three-piece structure adopt a lens with a positive refractive power as the first lens, which limits the viewing angle of this type of lens and affects the application range of this type of lens.

Contents of the invention

The technical problem to be solved by the present invention is to provide a micro-miniature lens with miniaturization and a large viewing angle, but still has good optical performance and high image resolution, aiming at the above-mentioned defects of the three-piece lens in the prior art. It can also meet the requirements and can reduce the production cost.

The solution adopted by the present invention to solve the technical problem is to provide a miniature lens, which sequentially includes a first lens, a second lens and a third lens along the optical axis from the object side to the image side. The first lens is a convex-concave lens with negative refractive power. The convex surface of the first lens faces the object side and the concave surface faces the image side. The second lens has positive refractive power. The third lens is a convex-concave lens with negative refractive power. The convex surface of the third lens faces the object side and the concave surface faces the image side.

The miniature lens satisfies the following conditions: 0.35≤BFL/TTL≤0.38; wherein, BFL is the back focal length of the miniature lens, and TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging plane.

The first lens satisfies the following condition: -4.5≤f ₁ /f≤-3.3; wherein, f ₁ is the effective focal length of the first lens, and f is the effective focal length of the miniature lens.

Wherein the second lens satisfies the following condition: 0.5≤f ₂ /f≤0.55; wherein, f ₂ is the effective focal length of the second lens, and f is the effective focal length of the miniature lens.

The third lens satisfies the following condition: -0.9≤f ₃ /f≤-0.8; wherein, f ₃ is the effective focal length of the third lens, and f is the effective focal length of the miniature lens.

Wherein the first lens and the third lens satisfy the following condition: 3.75≤f ₁ /f ₃ ≤5.5; wherein, f ₁ is the effective focal length of the first lens, and f ₃ is the effective focal length of the third lens.

Wherein at least one side of the first lens is an aspheric surface or both surfaces are aspheric surfaces.

Wherein at least one side of the second lens is an aspheric surface or both surfaces are aspheric surfaces.

Wherein at least one side of the third lens is an aspheric surface or both surfaces are aspheric surfaces.

Wherein the first lens, the second lens and the third lens are made of plastic material.

The miniature lens of the present invention may further include an aperture disposed between the first lens and the second lens.

The miniature lens implemented in the present invention has the following beneficial effects: the total length of the lens can be effectively shortened, the viewing angle can be improved, the aberration can be effectively corrected, and the resolution of the lens can be improved.

Description of drawings

In order to make the above objects, features, and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below with accompanying drawings.

FIG. 1 is a schematic diagram of the lens configuration and optical path of the first embodiment of the micro lens according to the present invention.

FIG. 2A is a field curvature diagram of the micro lens of FIG. 1 .

FIG. 2B is a distortion diagram of the micro lens of FIG. 1 .

2C, 2D, and 2E are lateral light fan diagrams of the miniature lens in FIG. 1 .

2F, 2G, and 2H are light spot diagrams of the micro-miniature lens in FIG. 1 .

FIG. 3 is a schematic diagram of the lens configuration and optical path of the second embodiment of the micro lens according to the present invention.

FIG. 4A is a field curvature diagram of the micro lens of FIG. 3 .

FIG. 4B is a distortion diagram of the miniature lens of FIG. 3 .

4C, 4D, and 4E are lateral light fan diagrams of the miniature lens in FIG. 3 .

4F, 4G, and 4H are light spot diagrams of the micro-miniature lens in FIG. 3 .

detailed description

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of the lens configuration and optical path of the first embodiment of the micro-lens according to the present invention. The micro lens 1 sequentially includes a first lens L11 , a diaphragm ST1 , a second lens L12 , a third lens L13 and an optical filter OF1 along the optical axis OA1 from the object side to the image side. The first lens L11 has a negative refractive power and is made of plastic material. The object side S11 is convex and the image side S12 is concave. Both the object side S11 and the image side S12 are aspheric surfaces. The second lens L12 has a positive refractive power and is made of plastic material. The object side S14 is convex and the image side S15 is convex. Both the object side S14 and the image side S15 are aspheric surfaces. The third lens L13 has negative refractive power and is made of plastic material. The object side S16 is convex and the image side S17 is concave. Both the object side S16 and the image side S17 are aspheric surfaces. The filter OF1 is flat glass, and its object side S18 and image side S19 are both flat.

In addition, in order to make the micro-miniature lens of the present invention maintain good optical performance, the micro-miniature lens 1 in the first embodiment needs to meet the following five conditions:

0.35≤BFL1/TTL1≤0.38 (1)

-4.5≤f1 ₁ /f1≤-3.3 (2)

0.5≤f1 ₂ /f1≤0.55 (3)

-0.9≤f1 ₃ /f1≤-0.8 (4)

3.75≤f1 ₁ /f1 ₃ ≤5.5 (5)

Wherein, BFL1 is the back focal length of the miniature lens 1, TTL1 is the distance from the object side S11 of the first lens L11 to the imaging plane IMA1 on the optical axis OA1, f1 is the effective focal length of the miniature lens ₁ , and f11 is the first lens The effective focal length of L11, f1 and ₂ are the effective focal length of the second lens L12, and f1 and ₃ are the effective focal length of the third lens L13.

Utilizing the above-mentioned design of the lens and the aperture ST1, the miniature lens 1 can effectively shorten the total length of the lens, increase the viewing angle, effectively correct aberrations, and improve the resolution of the lens.

Table 1 is a table of relevant parameters of each lens of the miniature lens 1 in Fig. 1, and the data in Table 1 shows that the effective focal length of the miniature lens 1 of the present embodiment is equal to 1.009mm, the aperture value is equal to 2.8, the viewing angle is equal to 82.74°, and the total lens length Equal to 2.301mm.

Table I

The concavity z of the aspheric surface of each lens in Table 1 is obtained by the following formula:

z=ch ² /{1+[1-(k+1)c ² h ² ] ^1/2 }+Ah ⁴ +Bh ⁶ +Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

in:

c: curvature;

h: the vertical distance from any point on the lens surface to the optical axis;

k: conic coefficient;

A～G: Aspheric coefficient.

Table 2 is a table of relevant parameters of the aspheric surface of each lens in Table 1, wherein k is a conic constant (Conic Constant), and A˜G are aspheric coefficients.

Table II

The miniature lens 1 of the first embodiment has a back focal length BFL1=0.866mm, a total lens length TTL1=2.301mm, an effective focal length f1=1.009mm of the miniature lens 1, and an effective focal length f1 ₌ -3.442mm of the first lens L11 , the effective focal length f1 ₂ of the second lens L12 = 0.541mm, the effective focal length f1 ₃ of the third lens L13 = -0.907mm, from the above data, it can be obtained that BFL1/TTL1 = 0.3764, f1 ₁ /f1 = -3.4113, f1 ₂ / f1=0.5362, f1 ₃ /f1=-0.8989, f1 ₁ /f1 ₃ =3.7949, all of which can satisfy the requirements of the above conditions (1) to (5).

In addition, the optical performance of the miniature lens 1 of the first embodiment can also meet the requirements, which can be seen from FIGS. 2A to 2H . FIG. 2A shows the Field Curvature diagram of the micro lens 1 of the first embodiment. FIG. 2B shows the distortion diagram of the micro lens 1 of the first embodiment. 2C, 2D, and 2E are the Transverse Ray Fan Plots of the miniature lens 1 of the first embodiment. FIG. 2F, FIG. 2G, and FIG. 2H show the spot diagram (Spot Diagram) of the micro-miniature lens 1 of the first embodiment.

It can be seen from FIG. 2A that the field curvature in the meridian (Tangential) direction and the sagittal (Sagittal) direction produced by the miniature lens 1 of the first embodiment for light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm is between -0.04 Between ㎜ and 0.01㎜. It can be seen from FIG. 2B that the distortion produced by the micro-miniature lens 1 of the first embodiment for light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm is between -1.3% and 0.4%. It can be seen from FIG. 2C, FIG. 2D, and FIG. 2E that the miniature lens 1 of the first embodiment has a pair of light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm, at image heights of 0.0000 mm, 0.5280 mm, and 0.8800 mm, respectively. The resulting lateral aberration values range from -12.0 μm to 10.0 μm. Fig. 2F, Fig. 2G, and Fig. 2H show that the miniature lens 1 of the first embodiment has a pair of light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm respectively at image heights of 0.000mm, 0.528mm, and 0.880mm. The root mean square (Root Mean Square) radii of the light spots are 3.459um, 1.718um, and 2.198um, respectively, and the corresponding geometrical radii of the light spots are 5.451um, 3.924um, and 5.892um. It is obvious that field curvature, distortion, and lateral aberration of the miniature lens 1 of the first embodiment can be effectively corrected, thereby obtaining better optical performance.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of a lens configuration and an optical path of a second embodiment of a micro lens according to the present invention. The micro lens 2 sequentially includes a first lens L21 , a diaphragm ST2 , a second lens L22 , a third lens L23 and an optical filter OF2 along the optical axis OA2 from the object side to the image side. The first lens L21 has negative refractive power and is made of plastic material. The object side S21 is convex and the image side S22 is concave. Both the object side S21 and the image side S22 are aspheric surfaces. The second lens L22 has positive refractive power and is made of plastic material. The object side S24 is convex and the image side S25 is convex. Both the object side S24 and the image side S25 are aspheric surfaces. The third lens L23 has negative refractive power and is made of plastic material. The object side S26 is convex and the image side S27 is concave. Both the object side S26 and the image side S27 are aspheric surfaces. The filter OF2 is flat glass, and its object side S28 and image side S29 are both flat.

In addition, in order to make the micro-miniature lens of the present invention maintain good optical performance, the micro-miniature lens 2 in the second embodiment needs to meet the following five conditions:

0.35≤BFL2/TTL2≤0.38 (6)

-4.5≤f2 ₁ /f2≤-3.3 (7)

0.5≤f2 ₂ /f2≤0.55 (8)

-0.9≤f2 ₃ /f2≤-0.8 (9)

3.75≤f2 ₁ /f2 ₃ ≤5.5 (10)

Wherein, BFL2 is the back focal length of the miniature lens 2, TTL2 is the distance from the object side S21 of the first lens L21 to the imaging plane IMA2 on the optical axis OA2, f2 is the effective focal length of the miniature lens ₂ , and f21 is the first lens The effective focal length of L21, f2 ₂ is the effective focal length of the second lens L22, and f2 ₃ is the effective focal length of the third lens L23.

Utilizing the above-mentioned design of the lens and the aperture ST2, the miniature lens 2 can effectively shorten the total length of the lens, improve the viewing angle, effectively correct aberrations, and improve the resolution of the lens.

Table 3 is a table of relevant parameters of each lens of the miniature lens 2 in Fig. 3, and the data in Table 3 shows that the effective focal length of the miniature lens 2 of the present embodiment is equal to 1.007mm, the aperture value is equal to 2.8, the viewing angle is equal to 82.75°, and the total length of the lens Equal to 2.303mm.

Table three

The aspherical surface sag z of each lens in Table 3 is obtained by the following formula:

z=ch ² /{1+[1-(k+1)c ² h ² ] ¹ / ² }+Ah ⁴ +Bh ⁶ +Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

in:

c: curvature;

h: the vertical distance from any point on the lens surface to the optical axis;

k: conic coefficient;

A～G: Aspheric coefficient.

Table 4 is a table of relevant parameters of the aspheric surface of each lens in Table 3, wherein k is a conic constant, and A˜G are aspherical coefficients.

Table four

The microminiature lens 2 of the second embodiment has its back focal length BFL2=0.822mm, the total lens length TTL2=2.303mm, the effective focal length f2=1.007mm of the microminiature lens 2, and the effective focal length f21 ₌ -4.373mm of the first lens L21 , the effective focal length f2 2 of the second lens L22 = 0.535 mm, the effective focal length f2 ₃ = -0.818 mm of the _third lens L23, from the above data, it can be obtained that BFL2/TTL2 = 0.3569, f2 ₁ /f2 = -4.3426, f2 ₂ / f2=0.5313, f2 ₃ /f2=-0.8123, f2 ₁ /f2 ₃ =5.3460, all of which can satisfy the requirements of the above conditions (6) to (10).

In addition, the optical performance of the miniature lens 2 of the second embodiment can also meet the requirements, which can be seen from FIGS. 4A to 4H . FIG. 4A shows the Field Curvature diagram of the micro lens 2 of the second embodiment. FIG. 4B shows the distortion diagram of the micro lens 2 of the second embodiment. 4C, 4D, and 4E are the Transverse Ray Fan Plots of the micro-miniature lens 2 of the second embodiment. FIG. 4F, FIG. 4G, and FIG. 4H show the spot diagram (Spot Diagram) of the micro-miniature lens 2 of the second embodiment.

It can be seen from FIG. 4A that the field curvature in the meridional (Tangential) direction and the sagittal (Sagittal) direction of the light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm produced by the micro-miniature lens 2 of the second embodiment is between -0.05 ㎜ to 0.02㎜. It can be seen from FIG. 4B that the distortion produced by the micro-miniature lens 2 of the second embodiment for light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm is between -1.4% and 0.4%. It can be seen from FIG. 4C, FIG. 4D, and FIG. 4E that the miniature lens 2 of the second embodiment has a pair of light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm, respectively, at image heights of 0.0000 mm, 0.5280 mm, and 0.8800 mm. The resulting lateral aberration values range from -10.0 μm to 9.0 μm. Fig. 4F, Fig. 4G, and Fig. 4H show that the micro-miniature lens 2 of the second embodiment has a pair of light rays with wavelengths of 0.436 μm, 0.546 μm, and 0.656 μm, respectively, at image heights of 0.000mm, 0.528mm, and 0.880mm. The root mean square (Root Mean Square) radii of the light spots are 1.441um, 2.027um, and 2.208um, respectively, and the corresponding geometrical radii of the light spots are 2.268um, 4.914um, and 6.108um. It is obvious that field curvature, distortion, and lateral aberration of the micro-miniature lens 2 of the second embodiment can be effectively corrected, thereby obtaining better optical performance.

In the above-mentioned embodiment, the object side and the image side of the first lens, the second lens and the third lens are all aspherical surfaces, but it can be understood that if some lenses in the first lens, the second lens and the third lens Or changing the object side or image side of all lenses into a spherical surface should also belong to the scope of the present invention.

In the above-mentioned embodiment, the first lens, the second lens and the third lens are all made of plastic material, but it can be understood that if some or all of the first lens, the second lens and the third lens are changed to glass Material should also belong to the category of the present invention.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can still make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention should be defined by the claims.

Claims (10)

1. a microminiature lens, it is characterised in that sequentially include to image side from thing side along optical axis:

First lens, these first lens are convexoconcave lens and have negative refractive power, the convex surface court of these the first lens To this thing side and concave surface towards this image side；

Second lens, these second lens have positive refractive power；And

3rd lens, the 3rd lens are convexoconcave lens and have negative refractive power, the convex surface court of the 3rd lens To this thing side and concave surface towards this image side；

This microminiature lens meets following condition:

0.35≤BFL/TTL≤0.38

Wherein, BFL is the back focal length of this microminiature lens, and TTL is that the thing side of these the first lens is to becoming Image planes distance on this optical axis.

2. microminiature lens as claimed in claim 1, it is characterised in that below these first lens meet Condition:

-4.5≤f₁/f≤-3.3

Wherein, f₁For the effective focal length of these the first lens, f is the effective focal length of this microminiature lens.

3. microminiature lens as claimed in claim 1, it is characterised in that below these second lens meet Condition:

0.5≤f₂/f≤0.55

Wherein, f₂For the effective focal length of these the second lens, f is the effective focal length of this microminiature lens.

4. microminiature lens as claimed in claim 1, it is characterised in that below the 3rd lens meet Condition:

-0.9≤f₃/f≤-0.8

Wherein, f₃For the effective focal length of the 3rd lens, f is the effective focal length of this microminiature lens.

5. microminiature lens as claimed in claim 1, it is characterised in that these first lens and this Three lens meet following condition:

3.75≤f₁/f₃≤5.5

Wherein, f₁For the effective focal length of these the first lens, f₃Effective focal length for the 3rd lens.

6. microminiature lens as claimed in claim 1, it is characterised in that this first lens at least one side For non-spherical surface.

7. microminiature lens as claimed in claim 1, it is characterised in that this second lens at least one side For non-spherical surface.

8. microminiature lens as claimed in claim 1, it is characterised in that the 3rd lens at least one side For non-spherical surface.

9. microminiature lens as claimed in claim 1, it is characterised in that these first lens, this second Lens and the 3rd lens are made up of plastic material.

10. microminiature lens as claimed in claim 1, it is characterised in that further include aperture, this aperture It is arranged between these first lens and this second lens.