CN113917655B

CN113917655B - Optical lens, fingerprint identification module and electronic equipment

Info

Publication number: CN113917655B
Application number: CN202111112276.5A
Authority: CN
Inventors: 张�林; 毕莹
Original assignee: TIANJIN JIHAO TECHNOLOGY CO LTD
Current assignee: TIANJIN JIHAO TECHNOLOGY CO LTD
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2023-11-21
Anticipated expiration: 2041-09-18
Also published as: CN113917655A

Abstract

The application provides an optical lens, a fingerprint identification module and electronic equipment, wherein the optical lens comprises a plurality of lenses, and the lenses comprise: a first lens, an object side surface and an image side surface of which are concave along an optical axis of the optical lens; a second lens, an object side surface of which is convex along the optical axis; and a third lens having an object side surface and an image side surface protruding along the optical axis, wherein the first lens to the third lens are sequentially disposed in a direction from an object side of the optical lens to an imaging surface of the optical lens.

Description

Optical lens, fingerprint identification module and electronic equipment

Technical Field

The present application relates to the field of optics, and in particular, to an optical lens, a fingerprint identification module, and an electronic device.

Background

With the development of full-face screens, fingerprint identification has become a basic configuration of mobile phone display screens. However, the volume of the optical lens in the current market is larger, and is limited by the number of lenses forming the optical system, the processing size of the lenses and the like, so that the pursuit of miniaturization of the fingerprint lens in the mobile phone cannot be satisfied, and the volume and the sensor size of the fingerprint lens circulated in the current market still occupy space due to overlarge size. In order to better match the internal space of a mobile phone, a miniaturized optical lens is needed to meet the requirements of the mobile phone market for an optical fingerprint lens.

The above information disclosed in this background section is only for enhancement of understanding of the background of the disclosure and therefore may contain information that does not form any part of the prior art nor that does it form the prior art that may teach one of ordinary skill in the art.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In order to solve the problem that the volume of a fingerprint lens circulated in the market occupies a large space, the application provides an optical lens, a fingerprint identification module and electronic equipment, which can realize the compact structure and miniaturization of the optical lens under the condition of ensuring the imaging performance.

A first aspect of the present application provides an optical lens, wherein the optical lens includes a plurality of lenses including: a first lens, an object side surface and an image side surface of which are concave along an optical axis of the optical lens; a second lens, an object side surface of which is convex along the optical axis; and a third lens having an object side surface and an image side surface protruding along the optical axis, wherein the first lens to the third lens are sequentially disposed in a direction from an object side of the optical lens to an imaging surface of the optical lens.

In a first aspect, the first lens has a negative refractive power.

In the first aspect, the second lens has positive refractive power.

In the first aspect, the third lens has positive refractive power.

In the first aspect, the optical lens further includes a stop disposed between the first lens and the second lens.

In a first aspect, 5< TTL/f < 8, where TTL is a distance on the optical axis from an intersection point of an object side surface of the first lens and the optical axis to the imaging plane, and f is a total focal length of the optical lens.

In a first aspect, 120 ° < fov <140 °, wherein fov is the field angle of the optical lens.

In a first aspect, -1 < f1/f 2< 0, wherein f1 is the focal length of the first lens and f2 is the focal length of the second lens.

In a first aspect, -2 < f1/f 3< -1, wherein f1 is the focal length of the first lens and f3 is the focal length of the third lens.

In a first aspect, 0< f1+f2 < 0.9, wherein f1 is the focal length of the first lens and f2 is the focal length of the second lens.

In a first aspect, -0.8 < f1+f3 < 0, wherein f1 is the focal length of the first lens and f3 is the focal length of the third lens.

In a first aspect, 1.5< ND1<1.7,1.5< ND2<1.7,1.5< ND3<1.7, wherein ND1, ND2, and ND3 are refractive indices of the first, second, and third lenses, respectively.

In the first aspect 50<VD1<70, 50<VD2<70, 50<VD3<70, wherein VD1, VD2, and VD3 are abbe numbers of the first lens, the second lens, and the third lens, respectively.

In a first aspect, the plurality of lenses is three lenses.

In the first aspect, 1.3 < BFL/f < 1.4, where BFL is a distance on the optical axis from an intersection point of an image side surface of the third lens and the optical axis to an imaging plane, and f is a total focal length of the optical lens.

In a first aspect, 3.9 < IMGH/f < 4, wherein IMGH is the diagonal length of the effective imaging area of the imaging face of the optical lens and f is the total focal length of the optical lens.

In a first aspect, 1.2< f number <1.6.

A second aspect of the present application provides a fingerprint recognition module, wherein the fingerprint recognition module includes an image sensor and the optical lens as described above, and the image sensor is disposed on an image side of the optical lens.

In a second aspect, the fingerprint recognition module further includes an infrared filter disposed above the image sensor for filtering infrared light entering the image sensor.

A third aspect of the present application provides an electronic device, where the electronic device includes a display screen and the fingerprint identification module as described above, and the display screen is disposed on an object side of the optical lens.

According to the optical lens, the fingerprint identification module and the electronic equipment, the compact structure and the miniaturization of the optical lens can be realized under the condition of ensuring the imaging performance.

In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a diagram showing a first example of an electronic device having an optical lens.

Fig. 2 shows an astigmatism curve of the optical lens shown in fig. 1.

Fig. 3 shows a distortion curve of the optical lens shown in fig. 1.

Fig. 4 presents the MTF curves of the optical lens shown in fig. 1.

Fig. 5 is a diagram showing a second example of an electronic device having an optical lens.

Fig. 6 shows an astigmatism curve of the optical lens shown in fig. 5.

Fig. 7 shows a distortion curve of the optical lens shown in fig. 5.

Fig. 8 presents the MTF curves of the optical lens shown in fig. 5.

Icon: 100-a display screen; 110-a first lens; 120-a second lens; 130-a third lens; 140-an optical filter; 150-an image sensor; 210-a first lens; 220-a second lens; 230-a third lens; 240-an optical filter; 250-an image sensor; STO-stop.

Detailed Description

The following detailed description is provided to assist the reader in obtaining a thorough understanding of the methods, apparatus, and/or systems described herein. However, various alterations, modifications and equivalents of the methods, devices and/or systems described herein will be apparent after an understanding of the present disclosure. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but rather, obvious variations may be made upon an understanding of the present disclosure, other than operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for the sake of clarity and conciseness.

The features described herein may be embodied in different forms and are not to be construed as limited to the examples described herein. Rather, the examples described herein have been provided solely to illustrate some of the many possible ways in which the methods, devices, and/or systems described herein may be implemented that will be apparent upon an understanding of the present disclosure.

Biometric technology has been widely applied to various terminal devices or electronic apparatuses. Biometric techniques include, but are not limited to, fingerprint recognition, palm print recognition, vein recognition, iris recognition, face recognition, living body recognition, anti-counterfeit recognition, and the like. Among them, fingerprint recognition generally includes optical fingerprint recognition, capacitive fingerprint recognition, and ultrasonic fingerprint recognition. With the rise of the full screen technology, the fingerprint identification module can be arranged in a local area or a whole area below the display screen, so that Under-screen (render-display) optical fingerprint identification is formed; alternatively, part or all of the optical fingerprint recognition module may be integrated into the display screen of the electronic device, thereby forming an In-screen (In-display) optical fingerprint recognition. The display screen may be an organic light emitting diode (Organic Light Emitting Diode, OLED) display screen or a liquid crystal display screen (LiquidCrystal Display, LCD) or the like. The fingerprint identification method generally comprises the steps of fingerprint image acquisition, preprocessing, feature extraction, feature matching and the like. Some or all of the above steps may be implemented by conventional Computer Vision (CV) algorithms, or by artificial intelligence (Artificial Intelligence, AI) based deep learning algorithms. The fingerprint identification technology can be applied to portable or mobile terminals such as smart phones, tablet computers and game devices, and other electronic devices such as intelligent door locks, automobiles and bank automatic teller machines, and is used for fingerprint unlocking, fingerprint payment, fingerprint attendance checking, identity authentication and the like.

A first aspect of the present disclosure provides an optical lens capable of achieving miniaturization while securing imaging performance.

In the embodiment of the present application, the first lens is a lens closest to the object (or subject), and the third lens is a lens closest to the imaging plane (or image sensor). In addition, in the present application, the radius of curvature, the effective radius and thickness of the lens, the distance (TTL) from the object side surface of the first lens to the imaging surface, the diagonal length (IMGH) of the effective imaging area of the imaging surface, and the focal length are all expressed in units of millimeters (mm).

Further, the thickness of the lenses, the distance between the lenses, and TTL are distances measured based on the optical axis of the lenses. Further, in the description of the shape of the lens, the expression that one surface of the lens is convex along the optical axis means that the paraxial region of the corresponding surface is convex, and the expression that one surface of the lens is concave along the optical axis means that the paraxial region of the corresponding surface is concave. Therefore, even when one surface of the lens is described as convex, an edge portion of the one surface of the lens may be concave. Also, even when one surface of the lens is described as concave, an edge portion of the one surface of the lens may be convex.

The optical lens includes three lenses. For example, the optical lens includes a first lens, a second lens, and a third lens disposed in order from an object side of the optical lens.

The object-side surface of the first lens is concave along the optical axis and the image-side surface of the first lens is concave along the optical axis. For example, the first lens has a negative refractive power.

The first lens may have an aspherical surface, such as an even aspherical surface. For example, both surfaces of the first lens are aspherical. The first lens may be formed using a material having high light transmittance and excellent workability. For example, the first lens is formed using plastic. The refractive index of the first lens is greater than 1.5 and less than 1.7.

The object side surface of the second lens is convex along the optical axis. For example, the second lens has positive refractive power.

The second lens may have an aspherical surface, such as an even aspherical surface. For example, both surfaces of the second lens are aspherical. The second lens may be formed using a material having high light transmittance and excellent workability. For example, the second lens is formed using plastic. The refractive index of the second lens is greater than 1.5 and less than 1.7.

The object-side surface of the third lens is convex along the optical axis, and the image-side surface of the third lens is convex along the optical axis. For example, the third lens has positive refractive power.

The third lens may have an aspherical surface. For example, both surfaces of the third lens are aspherical. The third lens may be formed using a material having high light transmittance and excellent workability. For example, the third lens is formed using plastic. The refractive index of the third lens is more than 1.5 and less than 1.7.

Any of the aspherical surfaces of the first lens to the third lens can be expressed by the following equation:

where Z is a distance sagittal height from an aspherical surface vertex when the aspherical surface is located at a height r in the optical axis direction, c represents a vertex curvature of the aspherical surface, k is a conic coefficient, and a2, a3, a4, a5, a6 are higher order aspherical coefficients.

The optical lens may have positive refractive power. That is, the combined focal length of the optical lens including the first lens, the second lens, and the third lens has a positive value. In some embodiments, the optical lens may further include an optical filter and/or a stop.

A filter may be disposed on the image side of the third lens, and the filter may be disposed between the third lens and an image sensor as described below. The filter blocks light of a partial wavelength so that a clear image can be achieved. For example, the filter is an infrared filter for blocking light of infrared wavelengths.

The diaphragm is arranged to control the amount of light incident on the lens. According to various embodiments, a stop may be provided between two adjacent lenses. For example, a diaphragm may be provided between the first lens and the second lens.

The second aspect of the present disclosure further relates to a fingerprint identification module, where the fingerprint identification module includes the optical lens of the first aspect and an image sensor, and the image sensor is disposed on an image side of the optical lens. The image sensor may form an imaging plane. For example, the surface of the photosensitive pixel array of the image sensor may form an imaging plane.

The fingerprint identification module further comprises an infrared filter, wherein the infrared filter is arranged above the image sensor and is used for filtering infrared light entering the image sensor

The third aspect of the present disclosure also relates to an electronic device, wherein the electronic device includes a display screen and the fingerprint recognition module as described above, and the display screen is disposed on the object side of the optical lens. Here, the electronic device may be a portable or mobile terminal such as a mobile phone, a tablet computer, a game device, and the like. In electronic equipment, fingerprint identification module sets up in the below of display screen for receive the light beam that carries fingerprint information, the optical lens in the fingerprint identification module is used for guiding the light beam of incidence to image sensor, image sensor converts the light beam into fingerprint signal and obtains fingerprint image based on fingerprint signal. In an embodiment, the display screen may provide a light source for the finger that illuminates the finger and reflects a light beam carrying the light signal.

In the optical lens, the fingerprint identification module and the electronic device related to the disclosure, the following conditional expressions can be satisfied:

in some embodiments, 5< TTL/f < 8.

In some embodiments, 120 ° < fov <140 °.

In some embodiments, -1 < f1/f 2< 0.

In some embodiments, -2 < f1/f 3< -1.

In some embodiments, 0< f1+f2 < 0.9.

In some embodiments, -0.8 < f1+f3 < 0.

In some embodiments, 1.5< nd1<1.7,1.5< nd2<1.7,1.5< nd3<1.7.

In some embodiments, 50<VD1<70, 50<VD2<70, 50<VD3<70.

In some embodiments, 1.2< f number <1.6.

In some embodiments, 1.3 < BFL/f < 1.4.

In some embodiments, 3.9 < IMGH/f < 4.

In the above expression, TTL is a distance on the optical axis from an intersection point of an object side surface of the first lens and the optical axis to the imaging surface, F is a total focal length of the optical lens, fov is a field angle of the optical lens, IMGH is a diagonal length of an effective imaging area of the imaging surface of the optical lens, where the effective imaging area is an area of a photosensitive pixel of the sensor, BFL is a distance from an intersection point of an image side surface of the third lens and the optical axis to the imaging surface, F1 is a focal length of the first lens, F2 is a focal length of the second lens, F3 is a focal length of the third lens, ND1, ND2, and ND3 are refractive indexes of the first lens, the second lens, and the third lens, respectively, VD1, VD2, and VD3 are abbe numbers of the first lens, the second lens, and the third lens, respectively, F number is inverse of a relative aperture of the optical lens, and relative = entrance diameter/focal length, that is, F = entrance diameter/focal length, F = F number of the entrance pupil number of the optical lens is represented by a large pupil number.

Here, according to 5< TTL/f < 8, miniaturization of the optical lens can be further achieved while ensuring imaging performance. Further, according to 120 ° < fov <140 °, an ultra-wide angle of the optical lens can be achieved.

Next, an electronic device according to several examples will be described.

First, an electronic device according to a first example will be described with reference to fig. 1. The electronic device comprises a display screen 100 and a fingerprint identification module, wherein the display screen 100 is arranged on the object side of the fingerprint identification module. The fingerprint recognition module comprises an optical lens and an image sensor 150, wherein the image sensor 150 is arranged on the image side of the optical lens. The fingerprint recognition module further comprises an infrared filter, and the infrared filter is arranged above the image sensor 150 and is used for filtering infrared light entering the image sensor 150.

The optical lens according to the first example includes a first lens 110, a second lens 120, and a third lens 130.

The first lens 110 has a negative refractive power. As shown in fig. 1, the object-side surface of the first lens 110 is concave along the optical axis, and the image-side surface of the first lens 110 is concave along the optical axis. The object-side surface of the second lens 120 is convex along the optical axis, and the image-side surface of the second lens 120 is convex along the optical axis. The object-side surface of the third lens 130 is convex along the optical axis, and the image-side surface of the third lens 130 is convex along the optical axis.

The optical lens further includes an optical filter 140 and a stop STO. The filter 140 is disposed between the third lens 130 and the image sensor 150, and the STO is disposed between the first lens 110 and the second lens 120.

The optical lens may be configured to realize a bright optical system. For example, the F-number of the optical lens is 1.46. The optical lens may have a field of view (fov) at ultra-wide angles, the entire field of view of the optical lens being 136.

In the optical lens according to the first example, the focal length f1 of the first lens is-0.70 mm, the focal length f2 of the second lens is 1.07mm, the focal length f3 of the third lens is 0.63mm, the total focal length (effective focal length) f of the optical lens is 0.368mm, the distance TTL on the optical axis from the intersection of the object side surface of the first lens and the optical axis to the imaging plane is 1.95mm, bfl is 0.50mm, and imgh is 1.46mm.

TABLE 1

Here, the conic coefficient is a higher-order term coefficient of the above formula.

Where OBJ stands for an object or a subject, S01 and S02 stand for an upper surface and a lower surface of a display screen, for example, respectively, S1 and S2 stand for an object side surface and an image side surface of a first lens, respectively, STO stands for a stop, S3 and S4 stand for an object side surface and an image side surface of a second lens, respectively, S5 and S6 stand for an object side surface and an image side surface of a third lens, respectively, S7 and S8 stand for an object side surface and an image side surface of a filter, respectively, and S9 stands for an imaging plane.

FIG. 2 presents an astigmatism curve for a first example optical lens; FIG. 3 presents a distortion curve of a first example optical lens; fig. 4 presents MTF curves for different image heights of the optical lens of the first example at different spatial frequencies. Table 1 presents the characteristics of the lenses of the optical lens according to the first example.

An electronic device according to a second example will be described with reference to fig. 5. The electronic device comprises a display screen 100 and a fingerprint identification module, wherein the display screen 100 is arranged on the object side of the fingerprint identification module. The fingerprint identification module comprises an optical lens and an image sensor 250, wherein the image sensor 250 is arranged on the image side of the optical lens. The fingerprint recognition module further comprises an infrared filter, and the infrared filter is arranged above the image sensor 250 and is used for filtering infrared light entering the image sensor 250.

The optical lens according to the second example includes a first lens 210, a second lens 220, and a third lens 230.

The first lens 210 has positive refractive power. As shown in fig. 5, the object-side surface of the first lens 210 is concave along the optical axis, and the image-side surface of the first lens 210 is concave along the optical axis. The object-side surface of the second lens 220 is convex along the optical axis, and the image-side surface of the second lens 220 is concave along the optical axis. The object-side surface of the third lens 230 is convex along the optical axis, and the image-side surface of the third lens 230 is convex along the optical axis.

The optical lens further includes an optical filter 240 and a stop STO. The filter 240 is disposed between the third lens 230 and the image sensor 250, and the STO is disposed between the first lens 210 and the second lens 220.

The optical lens may be configured to realize a bright optical system. For example, the F-number of the optical lens is 1.38. The optical lens may have a field of view (fov) at an ultra-wide angle, the entire field of view of the optical lens being 133.8 °.

In the optical lens according to the second example, the focal length f1 of the first lens is-0.79 mm, the focal length f2 of the second lens is 1.31mm, the focal length f3 of the third lens is 0.477mm, the total focal length (effective focal length) f of the optical lens is 0.373mm, the distance TTL on the optical axis from the intersection of the object side surface of the first lens and the optical axis to the imaging plane is 1.95mm, bfl is 0.49mm, and imgh is 1.46mm.

TABLE 2

Here, the effective radius is the net caliber (radius through which light actually passes) of the corresponding surface of the optical lens, and the conic coefficient is the higher-order term coefficient of the above formula.

FIG. 6 presents an astigmatism curve for a second example optical lens; FIG. 7 presents a distortion curve of a second example optical lens; fig. 8 presents MTF curves for different image heights of the optical lens of the second example at different spatial frequencies. Table 2 presents the characteristics of the lenses of the optical lens according to the second example.

Table 3 presents values of conditional expressions of the optical lenses according to the first example to the second example.

TABLE 3 Table 3

Conditional/implementation formula	1	2
			TTL/f	5.3	5.22
FOV	136°	133.8°
			f1/f2	-0.65	-0.60
f1/f3	-1.11	-1.66
			f1+f2	0.37	0.52
f1+f3	-0.07	-0.313
			ND1、VD1	1.54、55.9	1.54、55.9
ND2、VD2	1.54、55.9	1.54、55.9
			ND3、VD3	1.64、55.9	1.64、55.9
F number	1.46	1.38
			BFL/f	1.358	1.314
IMGH/f	3.97	3.91

According to the above example, miniaturization of the optical lens can be achieved while ensuring imaging performance.

While this disclosure includes particular examples, it will be apparent from an understanding of the disclosure of the application that various changes in form and details can be made therein without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in descriptive sense only and not for purposes of limitation. The description of features or aspects in each example will be considered applicable to similar features or aspects in other examples. Suitable results may be obtained if the described techniques are performed in a different order and/or if components in the described systems, frameworks, devices or circuits are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Thus, the scope of the disclosure is not to be limited by the specific embodiments, but by the claims and their equivalents, and all changes within the scope of the claims and their equivalents are to be interpreted as being included in the disclosure.

Claims

1. An optical lens, the optical lens comprising a plurality of lenses, the plurality of lenses comprising:

a first lens, an object side surface and an image side surface of which are concave along an optical axis of the optical lens;

a second lens, an object side surface of which is convex along the optical axis; and

a third lens having an object side surface and an image side surface which are convex along the optical axis,

wherein the first lens to the third lens are sequentially arranged along the direction from the object side of the optical lens to the imaging surface of the optical lens,

5< TTL/f < 8, wherein TTL is the distance on the optical axis from the intersection point of the object side surface of the first lens and the optical axis to the imaging surface, f is the total focal length of the optical lens,

1.3 < BFL/f < 1.4, wherein BFL is the distance on the optical axis from the intersection point of the image side surface of the third lens and the optical axis to the imaging surface, or 3.9 < IMGH/f < 4, wherein IMGH is the diagonal length of the effective imaging area of the imaging surface of the optical lens.

2. The optical lens of claim 1, wherein the first lens has a negative refractive power.

3. The optical lens of claim 1, wherein the second lens has positive refractive power.

4. The optical lens of claim 1, wherein the third lens has positive refractive power.

5. The optical lens of claim 1, further comprising a stop disposed between the first lens and the second lens.

6. The optical lens of any of claims 1-5, wherein 120 ° < fov <140 °, wherein fov is the field angle of the optical lens.

7. The optical lens according to any one of claims 1 to 5, wherein-1 < f1/f 2< 0, wherein f1 is a focal length of the first lens and f2 is a focal length of the second lens.

8. The optical lens according to any one of claims 1 to 5, characterized in that, -2 < f1/f 3< -1, wherein f1 is the focal length of the first lens and f3 is the focal length of the third lens.

9. The optical lens of any one of claims 1 to 5, wherein 0< f1+f2 < 0.9, wherein f1 is a focal length of the first lens and f2 is a focal length of the second lens.

10. The optical lens according to any one of claims 1 to 5, wherein-0.8 < f1+f3 < 0, wherein f1 is the focal length of the first lens and f3 is the focal length of the third lens.

11. The optical lens according to any one of claims 1 to 5, wherein,

1.5< ND1<1.7,1.5< ND2<1.7,1.5< ND3<1.7, wherein ND1, ND2, and ND3 are refractive indices of the first, second, and third lenses, respectively.

12. The optical lens according to any one of claims 1 to 5, wherein,

50<VD1<70, 50<VD2<70, 50<VD3<70, wherein VD1, VD2, and VD3 are abbe numbers of the first lens, the second lens, and the third lens, respectively.

13. The optical lens of any of claims 1-5 wherein the plurality of lenses is three lenses.

14. The optical lens according to any one of claims 1 to 5, characterized in that 1.2< f number <1.6.

15. A fingerprint recognition module, characterized in that the fingerprint recognition module comprises an image sensor and the optical lens according to any one of claims 1 to 14, the image sensor being arranged on the image side of the optical lens.

16. The fingerprint recognition module of claim 15, further comprising an infrared filter disposed over the image sensor for filtering infrared light entering the image sensor.

17. An electronic device, characterized in that the electronic device comprises a display screen and the fingerprint recognition module according to claim 15 or 16, the display screen being arranged at the object side of the optical lens.