TWI783230B - Under-screen fingerprint sensing module and electronic device - Google Patents

Abstract

An under-screen fingerprint sensing module configured to be disposed under a display panel, so as to sense a fingerprint of a finger on the display panel. The under-screen fingerprint sensing module includes an image sensor, an imaging lens, and a field lens. The image sensor is disposed under the display panel. The imaging lens is disposed between the display panel and the image sensor. The field lens is disposed between the display panel and the imaging lens. An electronic device is also provided.

Description

Under-display fingerprint sensor module and electronic device

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

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

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

A known optical sensor is to install a camera under a transparent display panel (such as an organic light-emitting diode display panel) to photograph fingerprints pressed on the transparent display panel, and the light source for illuminating the fingerprint is the transparent display panel emitted light. However, a general organic light emitting diode light source is a Lambertian source, and its luminous intensity has a cosine proportional relationship with the outgoing light angle, that is, the more inclined the emitted light, the weaker the intensity. Therefore, when the camera captures a fingerprint image, the closer to the edge of the finger the fingerprint is reflected and the light incident on the camera lens is more 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 lead to The brightness of the fingerprint image on the edge of the finger sensed by the image sensor is weaker, which in turn affects the accuracy and success rate of fingerprint identification.

The invention provides an under-screen fingerprint sensing module, which can sense fingerprint images with uniform brightness.

The invention provides an electronic device, the under-screen fingerprint sensing module can sense fingerprint images with uniform brightness.

An embodiment of the present invention provides an under-display fingerprint sensing module, which is configured under a display panel to sense a fingerprint of a finger on the display panel. The under-screen fingerprint sensing 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 disposed 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-display fingerprint sensing module of the embodiment of the present invention, since the light emitted from the finger in a direction approximately perpendicular to the display panel is converged on the image sensor by using a field lens, the image sensor The sensed images of the edge area of the finger and the central area of the finger are both 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 identification.

50: finger

52: Fingerprint

100: Electronic device

110: display panel

112: pixel

113, 115: light

114: upper surface

117:Criminal light

200: Under-screen fingerprint sensor module

210: image sensor

220: imaging lens

230: field lens

240: transparent colloid

250: middle frame

252: Light-transmitting opening

A: optical axis

D1: Maximum outer diameter

D2: Diagonal length

θ: included angle

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

FIG. 1 is a schematic partial cross-sectional view of an electronic device according to an embodiment of the present invention. Please refer to FIG. 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. A fingerprint 52 of a finger 50 on the panel 110 . The under-screen fingerprint sensing module 200 includes an image sensor 210 , an imaging lens 220 and a field lens 230 . Wherein, the imaging lens 220 is configured between the display panel 110 and the image sensor between the detectors 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, such as 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 (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 other various electronic devices.

In this embodiment, the light 113 emitted by the pixels 112 of the display panel 110 illuminates the finger 50 upwards, and the finger 50 reflects the light 113 into light 115 carrying the information of the fingerprint 52 . In this embodiment, the field lens 230 is used to converge the light 115 emitted from the finger 50 toward the direction approximately perpendicular to the display panel 110 on the image sensor 210, that is, the light 115 emitted from the finger 50 toward the direction approximately perpendicular to the display panel 110 The light 115 is first condensed by the field lens 230 to the imaging lens 220 , and then transmitted 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 will not be caused by only sensing The brightness of the image is reduced due to oblique light. In this way, the electronic device 100 and the under-display fingerprint sensor module 200 of this embodiment can sense a fingerprint image 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 tested. The ratio of the maximum outer diameter D1 of the field lens 230 to the diagonal length D2 of the sensing region of the image sensor 210 falls within a range from 4 to 10. In addition, the included 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 is pressed and the fingerprint can be sensed), so that the field lens 230 can collect light that is almost vertically downward 115 , and transmit such light 115 to the image sensor 210 to form a fingerprint image with uniform brightness. That is to say, 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 principal rays of the object space nearly parallel, and because of the telecentric design, the light 115 collected by the field lens 230 for the light 115 with different object heights in the object space The angles of light are similar. In this way, the brightness of the edge area and the central area of the fingerprint image can be made to be consistent.

In one 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, transparent The refractive index of the colloid 240 is, for example, 1.3.

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 is attached to the middle frame 250, and configured Between the light transmission opening 252 and the display panel 110 between.

To sum up, in the electronic device and the under-display fingerprint sensing module of the embodiment of the present invention, since the field lens is used to converge the light emitted from the finger in a direction approximately perpendicular to the display panel on the image sensor, Therefore, the images of the edge area of the finger and the central area of the finger sensed by the image sensor are contributed by the light emitted in a direction approximately perpendicular to the display panel, and the brightness of the image will not be caused by only sensing oblique light. reduce. 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 identification.

50: finger

52: Fingerprint

100: Electronic device

110: display panel

112: pixel

113, 115: light

114: upper surface

117:Criminal light

200: Under-screen fingerprint sensor module

210: image sensor

220: imaging lens

230: field lens

240: transparent colloid

250: middle frame

252: Light-transmitting opening

A: optical axis

D1: Maximum outer diameter

D2: Diagonal length

θ: included angle

Claims (14)

An under-screen fingerprint sensing module is arranged under a display panel to sense the fingerprint of a finger on the display panel. The under-screen fingerprint sensing module includes: an image sensor; an imaging lens , configured between the display panel and the image sensor; and a field lens, configured between the display panel and the imaging lens, wherein the field lens collects the image from the upper surface of the display panel and transmits it to the image The angle between the chief ray of the sensor and the optical axis of the imaging lens is less than 15 degrees, and 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-display fingerprint sensor module as claimed in claim 1, wherein the imaging lens and the field lens form a telecentric lens. The under-display fingerprint sensor module as described in claim 1, wherein the image sensor is arranged under a light-transmitting opening of a middle frame, the field lens is attached to the middle frame, and is arranged on the transparent between the light opening and the display panel. The under-display fingerprint sensor module as claimed in claim 1, wherein the maximum outer diameter of the field mirror is in the range of 30 mm to 50 mm. The under-screen fingerprint sensing module as claimed in claim 1, wherein there is an air gap between the field lens and the display panel. The under-screen fingerprint sensing module as claimed in item 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 transparent colloid has a refractive index less than The refractive index of the field lens. An electronic device, comprising: a display panel; and an under-screen fingerprint sensing module configured below the display panel to sense a fingerprint of a finger on the display panel, the under-screen fingerprint sensing module It includes: an image sensor arranged under the display panel; an imaging lens arranged between the display panel and the image sensor; and a field lens arranged between the display panel and the imaging lens, wherein The included 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 is less than 15 degrees, and the maximum outer diameter of the field lens and the image sensor The ratio of the diagonal lengths of the sensing regions falls within the range from 4 to 10. The electronic device as claimed in claim 7, wherein the imaging lens and the field lens form a telecentric lens. The electronic device as described in claim 7 further includes a middle frame with a light-transmitting opening, the image sensor is disposed under the light-transmitting opening, the field lens is attached to the middle frame, and is disposed on the light-transmitting opening. Between the light-transmitting opening and the display panel. The electronic device as claimed in claim 7, wherein the maximum outer diameter of the field mirror is in the range of 30 mm to 50 mm. The electronic device as claimed in claim 7, wherein an air gap exists between the field lens and the display panel. The electronic device as claimed in item 7, 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 . The electronic device as claimed in claim 7, wherein the display panel is a transparent display panel. The electronic device as claimed in claim 13, wherein the display panel is an OLED display panel.

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