CN113777759A

CN113777759A - Fingerprint identification optical lens

Info

Publication number: CN113777759A
Application number: CN202111195773.6A
Authority: CN
Inventors: 葛杰; 宋亮; 陈军
Original assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Current assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Priority date: 2021-10-14
Filing date: 2021-10-14
Publication date: 2021-12-10

Abstract

The invention relates to the technical field of optical lenses and discloses a fingerprint identification optical lens. The fingerprint identification optical lens is sequentially provided with the following components from an object side to an image side along an optical axis: the lens comprises a glass flat plate, a first lens, a second lens, a third lens and an optical filter, wherein a diaphragm is arranged between the second lens and the third lens; the first lens has negative focal power, and paraxial regions of the object side surface and the image side surface are both concave; the second lens has positive focal power, the paraxial region of the object side surface is a convex surface, and the paraxial region of the image side surface is a concave surface; the third lens has positive focal power, and paraxial regions of the object side surface and the image side surface are convex surfaces; the optical lens satisfies the following conditions: 2.4< OBH/TTL < 4; wherein, TTL is the total length from the bottom of the cover plate to the image surface, and OBH is the object height of the fingerprint identification optical lens. The fingerprint identification optical lens provided by the invention has good optical performance and meets the design requirements of wide angle, large aperture and fingerprint identification.

Description

Fingerprint identification optical lens

Technical Field

The invention relates to the field of optical lenses, in particular to a fingerprint identification optical lens which is suitable for smart devices such as smart phones.

Background

With the development trend of electronic products in a form of being thin, light, thin, short, and small, the small-sized photographing lens with good imaging quality is becoming the mainstream in the market at present. However, the existing fingerprint identification lens still has a large volume, so that the fingerprint module also occupies a large space, and the installation equipment cannot have a thinner body.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a fingerprint recognition optical lens, which can greatly limit the total length of the lens to be shortened on the basis of a large object height.

The fingerprint identification optical lens has smaller volume and good imaging quality.

In order to achieve the purpose, the invention adopts the main technical scheme that:

the invention provides a fingerprint identification optical lens, which is sequentially provided with the following components from an object side to an image side along an optical axis: the lens comprises a glass flat plate, a first lens, a second lens, a third lens and an optical filter, wherein a diaphragm is arranged between the second lens and the third lens; the first lens has negative focal power, and paraxial regions of the object side surface and the image side surface are both concave; the second lens has positive focal power, the paraxial region of the object side surface is a convex surface, and the paraxial region of the image side surface is a concave surface; the third lens has positive focal power, and paraxial regions of the object side surface and the image side surface are convex surfaces; the fingerprint identification optical lens meets the following conditional expression:

2.4<OBH/TTL<4

wherein, TTL is the total length from the bottom of the cover plate to the image surface, and OBH is the object height of the fingerprint identification optical lens. The condition is satisfied, and the lens has the characteristics of large object height and short total length.

Further, the fingerprint identification optical lens satisfies the following conditional expression:

1<F2/F3<3.2

wherein F2 is the second lens focal length, and F3 is the third lens focal length. The condition is satisfied, which is helpful for reducing aberration and improving resolution.

FNO≤1.5

wherein, FNO is the aperture value of the fingerprint identification optical lens. Satisfying the conditional expression indicates that the lens has a large aperture and a large light input amount.

0.7<CT2/CT1<1

wherein, CT2 is the total length from the object side surface of the first lens to the image plane, and CT1 is the total length from the front surface of the glass plate to the object side surface of the first lens. Satisfying the conditional expression shows that the lens has smaller total length and the fingerprint module has enough space.

OBH>7.8

wherein OBH is the optical lens object height. When the conditional expression is satisfied, the lens has large object height, and the size required by fingerprint identification is satisfied.

ANG≤62°

wherein the ANG is a maximum value of the surface angles of the first lens, the second lens or the third lens. The condition is satisfied, and the lens has a good surface shape and high mass production.

1.0<V2/V3<3.0

wherein V2 is the abbe number of the second lens, and V3 is the abbe number of the third lens. Satisfying the conditional expression helps to reduce the aberration of the optical lens.

HFOV>128°

the HFOV is a field angle of the fingerprint identification optical lens. The optical lens has larger zoom magnification and can image a larger object height to a smaller image plane by meeting the conditional expression.

The invention has the beneficial effects that: the invention provides a fingerprint identification optical lens, which adopts three lenses, and has the advantages of miniaturization, higher quality and the like through the matching of the focal power, the surface type, the center thickness of each lens, the axial distance between each lens and the like. The method is suitable for small portable electronic mobile equipment.

Drawings

FIG. 1 illustrates a schematic structural diagram of an optical lens for fingerprint recognition according to the present invention;

fig. 2 is a schematic structural diagram showing a fingerprint recognition optical lens according to embodiment 1 of the present invention;

fig. 3 shows an astigmatic field curvature diagram of a fingerprint recognition optical lens according to embodiment 1 of the present invention;

FIG. 4 is a distortion curve diagram of the optical lens for fingerprint recognition according to embodiment 1 of the present invention;

FIG. 5 is a graph showing an optical modulation transfer function curve of a fingerprint recognition optical lens according to embodiment 1 of the present invention;

fig. 6 is a schematic structural diagram showing a fingerprint recognition optical lens according to embodiment 2 of the present invention;

FIG. 7 is an astigmatic field curvature diagram of an optical lens for fingerprint recognition according to embodiment 2 of the present invention;

FIG. 8 is a diagram showing a distortion curve of an optical lens for fingerprint recognition in embodiment 2 of the present invention;

FIG. 9 is a graph showing an optical modulation transfer function curve of a fingerprint recognition optical lens according to embodiment 2 of the present invention;

fig. 10 is a schematic structural diagram showing a fingerprint recognition optical lens according to embodiment 2 of the present invention;

FIG. 11 is an astigmatic field curvature diagram of an optical lens for fingerprint recognition according to embodiment 3 of the present invention;

FIG. 12 is a diagram showing a distortion curve of an optical lens for fingerprint recognition in embodiment 3 of the present invention;

fig. 13 is a graph showing an optical modulation transfer function curve of a fingerprint identification optical lens according to embodiment 3 of the present invention.

In the figure: 1. a glass plate; 2. a first lens; 3. a second lens; 4. a third lens; 5. an optical filter; 6. a diaphragm; 7. and (4) an image plane.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

As shown in fig. 1, the present invention provides an optical lens for fingerprint recognition. The fingerprint identification optical lens is sequentially provided with the following components from an object side to an image side along an optical axis: the lens comprises a glass flat plate 1, a first lens 2, a second lens 3, a third lens 4, a filter 5 and an image plane 7. A diaphragm 6 is arranged between the second lens 3 and the third lens 4 and is used for adjusting the light flux of the optical lens. The first lens 2 has negative focal power, and paraxial regions of the object side surface and the image side surface are both concave. The second lens element 3 has positive refractive power, and has a convex object-side surface paraxial region and a concave image-side surface paraxial region. The third lens element 4 has positive refractive power, and both paraxial regions of the object-side surface and the image-side surface are convex.

Example 1

The following table specifically refers to the design parameters of the optical lens for fingerprint identification in this embodiment 1.

Table one (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 1. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm).

Watch 1 (a)

Table one (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 1.

Watch 1 (b)

Flour mark

3

4

5

6

8

9

K

-1.11E+00

2.77E-01

-9.90E+01

1.07E+01

-9.45E+01

-3.30E+00

A4

1.04E+01

-5.97E+00

7.59E+01

1.43E+01

-1.09E+01

4.35E+01

A6

-7.39E+01

7.42E+02

-5.20E+03

-1.81E+03

7.48E+03

-8.54E+03

A8

3.62E+02

-1.71E+04

2.42E+05

1.37E+05

-1.62E+06

8.13E+05

A10

-1.19E+03

2.03E+05

-7.48E+06

-1.05E+07

1.89E+08

-4.63E+07

A12

2.61E+03

-1.30E+06

1.48E+08

6.65E+08

-1.26E+10

1.68E+09

A14

-3.77E+03

4.16E+06

-1.80E+09

-2.50E+10

4.88E+11

-3.88E+10

A16

3.43E+03

-5.20E+06

1.21E+10

4.75E+11

-1.07E+13

5.57E+11

In this embodiment, specific parameters of the optical lens are shown in the following table:

watch 1 (c)

The lens shape and the lens properties of example 1 are clearly shown in tables one (a) and one (b).

Referring to fig. 2, which is an optical arrangement diagram of the optical lens for fingerprint identification in embodiment 1, it can be seen that the close arrangement of the lenses of the lens can realize the smaller structural feature of the lens.

From the astigmatic field curves in fig. 3, it is shown more clearly that: the maximum difference value of the astigmatism S line and the astigmatism T line of the lens is below 0.2mm, and the maximum value of the field curvature is below 0.2mm, which shows that the lens has better capability of improving the astigmatism and the field curvature.

From the distortion curve in fig. 4, it is shown more clearly that: the maximum distortion value of the optical lens is about 2%, which shows that the lens has good capability of improving distortion.

According to the optical modulation transfer function curve in fig. 5, it is clearly shown that the lens has good resolving power.

Example 2

Fig. 6 is a schematic view showing an optical arrangement of a fingerprint recognition optical lens according to embodiment 2 of the present invention. As shown in fig. 6, the optical lens for fingerprint recognition according to the exemplary embodiment of the present invention, in order from an object side to an image side along an optical axis, comprises: the lens comprises a glass flat plate, a first lens, a second lens, a diaphragm, a third lens, an optical filter and an image plane.

The design parameters of the optical lens for fingerprint identification of the present embodiment refer to the following table.

Table two (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 2. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm).

Watch two (a)

Table two (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 2.

Watch two (b)

Flour mark

3

4

5

6

8

9

K

-1.88E+00

2.48E+00

-9.69E+01

1.08E+01

-9.49E+01

-3.01E+00

A4

1.16E+01

2.80E+00

5.93E+01

1.07E+01

-2.73E+01

2.63E+01

A6

-9.33E+01

8.22E+02

-3.24E+03

-2.42E+03

4.60E+03

-4.61E+03

A8

4.88E+02

-2.69E+04

1.16E+05

3.09E+05

-2.70E+05

3.52E+05

A10

-1.69E+03

4.11E+05

-2.52E+06

-2.40E+07

-1.58E+07

-1.63E+07

A12

3.89E+03

-3.16E+06

3.17E+07

1.11E+09

3.39E+09

4.89E+08

A14

-5.87E+03

1.17E+07

-2.07E+08

-2.93E+10

-2.19E+11

-9.39E+09

A16

5.56E+03

-1.63E+07

4.76E+08

4.06E+11

7.06E+12

1.11E+11

watch two (c)

According to the second table (a) and the second table (b), the lens shape and the attributes of the lens of the current embodiment are clearly shown.

Referring to fig. 6, which is an optical arrangement diagram of the optical lens for fingerprint identification in embodiment 2, it can be seen that the close arrangement of the lenses of the lens can realize the smaller structural features of the lens.

According to the astigmatic field curvature curve in fig. 7, it is clearly shown that the maximum difference between the astigmatic S line and the T line of the lens is below 0.2mm, and the maximum value of the field curvature is below 0.2mm, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion curve in fig. 8, it is clearly shown that the maximum distortion value of the optical lens is about 3%, which indicates that the lens has a good capability of improving distortion.

According to the optical modulation transfer function curve in fig. 9, it is clearly shown that the lens has good resolving power.

Example 3

Fig. 10 is a schematic view showing an optical arrangement of a fingerprint recognition optical lens according to embodiment 3 of the present invention. As shown in fig. 10, the optical lens for fingerprint recognition according to the exemplary embodiment of the present invention, in order from an object side to an image side along an optical axis, comprises: the lens comprises a glass flat plate, a first lens, a second lens, a diaphragm, a third lens, an optical filter and an image plane.

Table three (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 3. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm).

Watch III (a)

Table three (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 3.

Watch III (b)

Flour mark

3

4

5

6

8

9

K

-1.313E+00

-2.622E-01

-9.888E+01

1.134E+01

-9.900E+01

-2.191E+00

A4

7.457E+00

1.826E+00

1.049E+01

2.673E+01

-1.399E+01

3.449E-01

A6

-4.836E+01

3.259E+02

-4.593E+02

-3.669E+03

2.805E+03

-1.848E+02

A8

2.198E+02

-9.189E+03

1.279E+04

2.548E+05

-2.071E+05

8.583E+03

A10

-6.563E+02

1.271E+05

-2.589E+05

-1.040E+07

8.667E+06

-1.979E+05

A12

1.267E+03

-8.982E+05

3.351E+06

2.574E+08

-2.226E+08

2.748E+06

A14

-1.543E+03

3.089E+06

-2.613E+07

-3.799E+09

3.573E+09

-2.349E+07

A16

1.119E+03

-4.132E+06

1.118E+08

3.075E+10

-3.492E+10

1.183E+08

watch III (c)

According to table three (a) and table three (b), the lens shape and various attributes of the lens of the current embodiment are clearly shown.

Referring to fig. 10, which is an optical arrangement diagram of the optical lens for fingerprint identification in embodiment 3, it can be seen that the close arrangement of the lenses of the lens can realize the smaller structural features of the lens.

According to the astigmatic field curvature curve in fig. 11, it is clearly shown that the maximum difference between the astigmatic S line and the T line of the lens is below 0.2mm, and the maximum value of the field curvature is below 0.2mm, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion curve in fig. 12, it is clearly shown that the maximum distortion value of the optical lens is about 2.5%, which shows that the lens has a good capability of improving distortion.

According to the optical modulation transfer function curve in fig. 13, it is clearly shown that the lens has good resolving power.

Although embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are illustrative and not restrictive, and that those skilled in the art may make changes, modifications, substitutions and alterations to the above embodiments without departing from the scope of the present invention.

Claims

1. A fingerprint recognition optical lens, characterized by: along the optical axis from the object side to the image side are arranged in sequence: the lens comprises a glass flat plate, a first lens, a second lens, a third lens and an optical filter, wherein a diaphragm is arranged between the second lens and the third lens;

the first lens has negative focal power, and paraxial regions of the object side surface and the image side surface are both concave;

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

the third lens has positive focal power, and paraxial regions of the object side surface and the image side surface are convex surfaces;

the optical lens satisfies the following conditions:

2.4<OBH/TTL<4

wherein, TTL is the total length from the bottom of the cover plate to the image surface, and OBH is the object height of the fingerprint identification optical lens.

2. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

1<F2/F3<3.2

wherein F2 is the second lens focal length, and F3 is the third lens focal length.

3. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

FNO≤1.5

wherein, FNO is the aperture value of the fingerprint identification optical lens.

4. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

0.7<CT2/CT1<1

wherein, CT2 is the total length from the object side surface of the first lens to the image plane, and CT1 is the total length from the front surface of the glass plate to the object side surface of the first lens.

5. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

OBH>7.8

wherein OBH is the optical lens object height.

6. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

ANG≤62°

wherein the ANG is a maximum value of the surface angles of the first lens, the second lens or the third lens.

7. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

1.0<V2/V3<3.0

wherein V2 is the abbe number of the second lens, and V3 is the abbe number of the third lens.

8. The optical lens for fingerprint recognition according to claim 1, wherein the optical lens satisfies the following condition:

HFOV>128°

the HFOV is a field angle of the fingerprint identification optical lens.