WO2020248809A1 - Under-display fingerprint sensing module and electronic apparatus - Google Patents

Abstract

Provided are an under-display fingerprint sensing module and an electronic apparatus. The under-display fingerprint sensing module is used for being configured below a display panel so as to sense a fingerprint of a finger on the display panel. The under-display fingerprint sensing module comprises an image sensor, an imaging lens, and a field lens, wherein the image sensor is configured below the display panel, the imaging lens is configured between the display panel and the image sensor, and the field lens is configured between the display panel and the imaging lens.

Description

Under-screen fingerprint sensing module and electronic device Technical field

The invention relates to a fingerprint sensing module and an electronic device, in particular to an under-screen fingerprint sensing module and an electronic device.

Background technique

With the development of handheld electronic devices (such as smart phones, tablet computers, etc.) toward a high screen-to-body ratio, there is not enough area on the front of the electronic device to install a traditional capacitive fingerprint sensor. To solve this problem, side fingerprint sensors, back fingerprint sensors and even other biometric sensors (such as face sensing) have been developed. However, the side fingerprint sensor has a small sensing area, and the back fingerprint sensor may not be used when the electronic device is placed on the desktop. The face sensor is expensive, easily damaged by moisture, and cannot be used when wearing a mask. problem.

One solution is to place the fingerprint sensor under the screen and sense the fingerprint by penetrating the screen. This is the under-screen fingerprint sensor solution. Under-screen fingerprint sensors can be divided into ultrasonic sensors and optical sensors. Ultrasonic sensors are more expensive, while optical sensors have the advantages of lower cost and high accuracy.

An existing optical sensor is to set up a camera under a transparent display panel (such as an organic light-emitting diode display panel) to capture fingerprints pressed on the transparent display panel, and the light source to illuminate the fingerprint is emitted by the transparent display panel Light. However, the general organic light-emitting diode light source is a Lambertian source, and its luminous intensity is in a cosine ratio with the light exit angle, that is, the more inclined the light is emitted, the weaker the intensity of the light. Therefore, when the camera captures a fingerprint image, the closer the fingerprint is to the edge of the finger and the light that enters the camera lens is obliquely incident on the lens, the more it is contributed by the oblique light emitted by the organic light-emitting diode light source, which will cause the image sensor The weaker the brightness of the fingerprint image at the edge of the finger is sensed, which affects the accuracy and success rate of fingerprint recognition.

Summary of the invention

The present invention is directed to an under-screen fingerprint sensing module, which can sense fingerprint images with uniform brightness.

The present invention is directed to an electronic device whose under-screen fingerprint sensing module can sense fingerprint images with uniform brightness.

An embodiment of the present invention provides an under-screen fingerprint sensor module, which is configured under a display panel to sense the fingerprint of a finger on the display panel. The under-screen fingerprint sensor module includes an image sensor, an imaging lens and a field mirror. The image sensor is arranged under the display panel, and the imaging lens is arranged between the display panel and the image sensor. The field lens is arranged between the display panel and the imaging lens.

An embodiment of the present invention provides an electronic device including a display panel and the above-mentioned under-screen fingerprint sensing module, wherein the under-screen fingerprint sensing module is disposed under the display panel.

In the electronic device and the under-screen fingerprint sensing module of the embodiment of the present invention, since the field lens is used to make the light emitted from the finger in the direction approximately perpendicular to the display panel converge on the image sensor, the finger sensed by the image sensor The images in the edge area and the central area of the finger are all contributed by the light emitted in a direction approximately perpendicular to the display panel, and the brightness of the image will not decrease because only oblique light is sensed. In this way, the electronic device and the under-screen fingerprint sensing module of the embodiment of the present invention can sense a fingerprint image with uniform brightness, thereby improving the accuracy and success rate of fingerprint recognition.

Description of the drawings

FIG. 1 is a schematic partial cross-sectional view of an electronic device according to an embodiment of the invention.

Description of reference signs

50: finger

52: Fingerprint

100: electronic device

110: display panel

112: pixels

113, 115: light

114: upper surface

117: Chief Ray

200: Under-screen fingerprint sensor module

210: Image sensor

220: imaging lens

230: field lens

240: transparent colloid

250: middle frame

252: light opening

A: Optical axis

D1: Maximum outer diameter

D2: Diagonal length

T1: pitch

θ: included angle

Detailed ways

Reference will now be made in detail to the exemplary embodiments of the present invention, and examples of the exemplary embodiments are illustrated in the accompanying drawings. Whenever possible, the same reference symbols are used in the drawings and the description to indicate the same or similar parts.

FIG. 1 is a schematic partial cross-sectional view of an electronic device according to an embodiment of the invention. 1, the electronic device 100 of this embodiment includes a display panel 110 and an under-screen fingerprint sensing module 200, wherein the under-screen fingerprint sensing module 200 is disposed under the display panel 110 to sense the display panel 110 Fingerprint 52 on a finger 50. The under-screen fingerprint sensor module 200 includes an image sensor 210, an imaging lens 220, and a field lens 230. The imaging lens 220 is disposed between the display panel 110 and the image sensor 210, and the field lens 230 is disposed between the display panel 110 and the imaging lens 220.

In this embodiment, the display panel 110 is a transparent display panel, for example, an organic light emitting diode display panel. Alternatively, in other embodiments, the display panel 110 may also be a liquid crystal display panel. The image sensor 210 is, for example, a complementary metal oxide semiconductor image sensor (complementary metal oxide semiconductor image sensor, CMOS image sensor, CIS). However, in other embodiments, the image sensor 210 may also be a charge coupled device (CCD). The electronic device 100 is, for example, a smart phone, a tablet computer, a notebook computer, or various other electronic devices.

In this embodiment, the light 113 emitted by the pixel 112 of the display panel 110 illuminates the finger 50 upward, and the finger 50 reflects the light 113 into the light 115 that carries the information of the fingerprint 52. In this embodiment, the field lens 230 is used to make the light 115 emitted from the finger 50 in a direction approximately perpendicular to the display panel 110 converge on the image sensor 210, that is, the light emitted from the finger 50 in a direction approximately perpendicular to the display panel 110 115 is focused on the imaging lens 220 by the field lens 230, and then transferred to the sensing area of the image sensor 210 by the imaging lens 220 to form an image. Therefore, the images of the edge area of the finger 50 and the central area of the finger 50 sensed by the image sensor 210 are all contributed by the light 115 emitted in a direction approximately perpendicular to the display panel 110, and it will not only sense the oblique direction. Light causes the image brightness to decrease. In this way, the electronic device 100 and the under-screen fingerprint sensing module 200 of this embodiment can sense fingerprint images with uniform brightness, thereby improving the accuracy and success rate of fingerprint recognition.

In this embodiment, the maximum outer diameter D1 of the field lens 230 falls within the range of 30 mm to 50 mm, depending on the area of the finger to be measured. The ratio of the maximum outer diameter D1 of the field lens 230 to the diagonal length D2 of the sensing area of the image sensor 210 falls within a range from 4 to 10. In addition, the angle θ between the chief ray 117 collected by the field lens 230 from the upper surface 114 of the display panel 110 and transmitted to the image sensor 210 and the optical axis A of the imaging lens 220 is less than 15 degrees. In other words, the area of the field lens 230 is close to the area of the entire fingerprint sensing area (that is, the area on the upper surface 114 where the finger can be pressed and the fingerprint can be sensed), so that the field lens 230 can collect almost vertically downward The light 115 is transmitted to the image sensor 210 to form a fingerprint image with uniform brightness. In other words, the imaging lens 220 and the field lens 230 form a telecentric lens.

That is to say, in this embodiment, a field lens 230 is added under the display panel 110 to make the chief ray of the object space nearly parallel, and because of the telecentric design, light 115 with different object heights in the object space is collected by the field lens 230. The light receiving angles are similar. In this way, the brightness of the edge area and the central area of the fingerprint image can be aligned.

In an embodiment, there is an air gap between the field lens 230 and the display panel 110. However, in another embodiment, there is a transparent colloid 240 between the field lens 230 and the display panel 110 so that the field lens 230 is attached to the display panel 110, wherein the refractive index of the transparent colloid 240 is smaller than that of the field lens, and is transparent. The refractive index of the colloid 240 is 1.3, for example.

In this embodiment, the electronic device 100 further includes a middle frame 250 with a light-transmitting opening 252, wherein the image sensor 210 is disposed under the light-transmitting opening 252, and the field lens 230 rests on the middle frame 250 and is disposed in the transparent opening 252. Between the light opening 252 and the display panel 110.

To sum up, in the electronic device and the under-screen fingerprint sensing module of the embodiment of the present invention, since the field lens is used to condense the light emitted from the finger in the direction approximately perpendicular to the display panel on the image sensor, the image sensor The sensed images of the edge area of the finger and the central area of the finger are all contributed by the light emitted in a direction approximately perpendicular to the display panel, and the brightness of the image will not decrease because only oblique light is sensed. In this way, the electronic device and the under-screen fingerprint sensing module of the embodiment of the present invention can sense a fingerprint image with uniform brightness, thereby improving the accuracy and success rate of fingerprint recognition.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: It is still possible to modify the technical solutions described in the foregoing embodiments, or equivalently replace some or all of the technical features; these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention range.

Claims (18)

An under-screen fingerprint sensing module, characterized in that it is disposed under a display panel to sense fingerprints of a finger on the display panel, and the under-screen fingerprint sensing module includes: Image Sensor; An imaging lens arranged between the display panel and the image sensor; and The field lens is arranged between the display panel and the imaging lens. The under-screen fingerprint sensing module according to claim 1, wherein the ratio of the maximum outer diameter of the field lens to the diagonal length of the sensing area of the image sensor is from 4 to 10 In the range. The under-screen fingerprint sensing module of claim 1, wherein the chief ray collected by the field lens from the upper surface of the display panel and transmitted to the image sensor and the main ray of the imaging lens The angle of the optical axis is less than 15 degrees. The under-screen fingerprint sensing module of claim 1, wherein the imaging lens and the field lens form a telecentric lens. The under-screen fingerprint sensor module according to claim 1, wherein the image sensor is disposed under the transparent opening of the middle frame, and the field lens is supported on the middle frame and is disposed on the middle frame. Between the transparent opening and the display panel. The under-screen fingerprint sensor module according to claim 1, wherein the maximum outer diameter of the field lens falls within a range of 30 mm to 50 mm. The under-screen fingerprint sensor module of claim 1, wherein there is an air gap between the field lens and the display panel. The under-screen fingerprint sensing module according to claim 1, wherein there is a transparent colloid between the field lens and the display panel, so that the field lens is attached to the display panel, wherein The refractive index of the transparent colloid is smaller than the refractive index of the field lens. An electronic device, characterized in that it comprises: Display panel; and The under-screen fingerprint sensing module is configured under the display panel to sense the fingerprint of a finger on the display panel, and the under-screen fingerprint sensing module includes: The image sensor is arranged under the display panel; An imaging lens arranged between the display panel and the image sensor; and The field lens is arranged between the display panel and the imaging lens. 9. The electronic device according to claim 9, wherein the ratio of the maximum outer diameter of the field lens to the diagonal length of the sensing area of the image sensor falls within a range from 4 to 10. 8. The electronic device of claim 9, wherein the angle between the chief ray collected by the field lens from the upper surface of the display panel and transmitted to the image sensor and the optical axis of the imaging lens Less than 15 degrees. 9. The electronic device according to claim 9, wherein the imaging lens and the field lens form a telecentric lens. 9. The electronic device according to claim 9, further comprising a middle frame having a light-transmitting opening, the image sensor is disposed under the light-transmitting opening, and the field lens is supported on the middle frame, And is arranged between the transparent opening and the display panel. 9. The electronic device according to claim 9, wherein the maximum outer diameter of the field lens falls within a range of 30 mm to 50 mm. 9. The electronic device of claim 9, wherein there is an air gap between the field lens and the display panel. 8. The electronic device of claim 9, wherein a transparent colloid is present between the field lens and the display panel, so that the field lens is attached to the display panel, wherein the refraction of the transparent colloid The rate is less than the refractive index of the field lens. 9. The electronic device according to claim 9, wherein the display panel is a transparent display panel. 18. The electronic device of claim 17, wherein the display panel is an organic light emitting diode display panel.

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