TWM608710U - Under-screen fingerprint sensing device - Google Patents

Abstract

An under-screen fingerprint sensing device including an image sensor and a controller is provided. The image sensor is disposed under a display. The display emits an illumination light transmitted to a finger pressing on the display. The finger reflects the illumination light into a signal light carrying fingerprint information of the finger. The signal light passes through the display and then form a fingerprint image on the image sensor. The controller is electrically connected to the image sensor and configured to process the fingerprint image sensed by the image sensor. The controller is configured to calculate inner products of gray levels on axes in two different directions and a Haar-like feature, whereby determining whether the fingerprint image is from a real finger or a fake finger.

Description

Under-screen fingerprint sensing device

This new creation relates to a sensing device, and in particular to a fingerprint sensing device.

With the development of portable electronic devices toward a larger screen-to-body ratio, the capacitive fingerprint sensor originally placed on the front of the electronic device is no longer applicable, and needs to be changed to be placed on the side or back of the electronic device. However, the fingerprint sensor placed on the side or the back is inconvenient to use, so an under-screen fingerprint sensor has been developed.

Under-screen fingerprint sensors can be roughly divided into optical fingerprint sensors and ultrasonic fingerprint sensors. Among them, optical fingerprint sensors are cheaper and more suitable for mass production. Since fingerprint sensing is critical to the security of the user's personal data, it is still necessary to develop an anti-spoofing function. For example, a person who intends to steal personal data may collect a user's fingerprint in the environment and make a fake finger with the fingerprint, and then press the electronic device with the fake finger to achieve successful fingerprint recognition and unlock. Therefore, it is necessary to develop a fingerprint sensor that can recognize fake fingers instead of real fingers to further enhance the security of the user's personal data.

This new creation provides an under-screen fingerprint sensing device, which can identify real fingers and fake fingers.

An embodiment of the present invention proposes an under-screen fingerprint sensing device for matching with a display. The display emits an illuminating light, which is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a carrying finger A signal light of fingerprint information. The under-screen fingerprint sensor includes an image sensor and a controller. The image sensor is arranged under the display, and the signal light penetrates the display to form a fingerprint image on the image sensor. The controller is electrically connected to the image sensor, and processes the fingerprint image sensed by the image sensor, and performs the function of the grayscale value and the Haar-like feature on the two axes of the fingerprint image in different directions. The inner product is used to determine whether the fingerprint image is from a real finger or a fake finger.

An embodiment of the present invention proposes an under-screen fingerprint sensing device for matching with a display. The display emits an illuminating light, which is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a carrying finger A signal light of fingerprint information. The under-screen fingerprint sensor includes an image sensor and a controller. The image sensor is arranged under a display, and the signal light penetrates the display to form a fingerprint image on the image sensor. The controller is electrically connected to the image sensor and used for processing the fingerprint image sensed by the image sensor. The controller is used to calculate the average gray level of a central area of the fingerprint image and the respective average gray levels of the two peripheral areas on both sides of the central area, and thereby determine whether the fingerprint image is from a real finger or a fake finger.

An embodiment of the present invention proposes an under-screen fingerprint sensing device for matching with a display. The display emits an illuminating light, which is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a carrying finger A signal light of fingerprint information. The under-screen fingerprint sensor includes an image sensor and a controller. The image sensor is arranged under a display, and the signal light penetrates the display to form a fingerprint image on the image sensor. The controller is electrically connected to the image sensor and used for processing the fingerprint image sensed by the image sensor. The controller is used to internally product the grayscale values on the two axes of the fingerprint image in different directions and a Haar feature to obtain a first result. The controller is used to calculate the average gray scale of a central area of the fingerprint image and the respective gray scale averages of the two peripheral areas on both sides of the central area to obtain a second result. The controller is used to synthesize the first result and the second result to determine whether the fingerprint image is from a real finger or a fake finger.

In the under-screen fingerprint sensing device of the embodiment of the present invention, the controller performs the inner product of the grayscale values on the two axes of the fingerprint image in different directions and a Haar feature, and/or calculates the fingerprint image The average gray level of the central area and the average gray levels of the two peripheral areas on both sides of the central area are used to determine whether the fingerprint image comes from a real finger or a fake finger. Therefore, the under-screen fingerprint sensing device of the inventive embodiment of the present invention can achieve the effect of anti-spoofing in fingerprint sensing, thereby improving the security of the user's personal data.

FIG. 1 is a schematic cross-sectional view of an electronic device according to an embodiment of the new creation. Please refer to FIG. 1, the electronic device 100 of this embodiment includes a display 105 and an under-screen fingerprint sensor 200. The electronic device 100 is, for example, a smart phone, a tablet computer, a notebook computer, a personal digital assistant (PDA) or other appropriate electronic devices. The under-screen fingerprint sensor device 200 is used to match with a display 105 and includes an image sensor 210 and a controller 230. The image sensor 210 is disposed under the display 105. The display 105 emits an illuminating light 60, and the illuminating light 60 is transmitted to a finger 50 pressed on the display 105, and the finger 50 reflects the illuminating light 60 into a signal light 70 carrying fingerprint information of the finger. The signal light 70 penetrates the display 105 to form a fingerprint image on the image sensor 210. In this way, the image sensor 210 can sense the fingerprint image of the finger 50. The controller 230 is electrically connected to the image sensor 210 and used for processing the fingerprint image sensed by the image sensor 210.

In this embodiment, the display 105 includes a cover glass 120, a linear polarizer 116, a phase retardation film 114, and an organic light emitting diode display panel 112. The finger presses on the glass cover 120. The linear polarizer 116 is disposed between the glass cover 120 and the image sensor 210. The phase retardation film 114 is disposed between the linear polarizer 116 and the image sensor 210. The phase retardation film 114 is, for example, a wave plate, which may be formed of the material of the display itself, or an additional wave plate. Formed. The organic light emitting diode display panel 112 is disposed between the phase retardation film 114 and the image sensor 210. In other embodiments, a liquid crystal display panel, a micro-light-emitting diode display panel, an electrophoretic display panel, or other suitable display panels can also be used to replace the organic light-emitting diode display panel 112.

In this embodiment, the under-screen fingerprint sensing device 200 further includes a lens 220 disposed on the path of the signal light 70 and located between the display 105 and the image sensor 210. The lens 220 may include one or more lenses, which can image the signal light 70 on the image sensor 210 to form a fingerprint image on the image sensor 210.

Specifically, the illuminating light 60 emitted by the organic light emitting diode display panel 112 does not have polarization, and after it penetrates the phase retardation film 114, it still does not have polarization. However, when the illumination light 60 penetrates the linear polarizer 116, it will have a polarization direction K0, where the polarization direction K0 can be decomposed into two components, a first polarization direction K1 and a second polarization direction K2, as shown in FIGS. 2A and 2B As shown, the first polarization direction K1 is the P polarization direction, and the second polarization direction K2 is the S polarization direction. In other words, the illumination light 60 having the polarization direction K0 can be regarded as a combination of the illumination light 62 having the first polarization direction K1 and the illumination light 64 having the second polarization direction K2.

FIG. 2A illustrates a situation in which the illumination light with a P polarization direction in FIG. 1 is reflected by a finger, and FIG. 2B illustrates a situation in which the illumination light with an S polarization direction in FIG. 1 is reflected by a finger. 1, 2A and 2B, the illumination light 62 with the first polarization direction K1 travels in the glass cover 120 (as shown in FIG. 2A), and is partially reflected by the finger 50 at the upper surface 122 of the glass cover 120 as a signal Light 72, and another part of the illuminating light 82 is transmitted in the finger 50. On the other hand, the illuminating light 64 with the second polarization direction K2 travels in the glass cover 120 (as shown in FIG. 2B), and is partially reflected by the finger 50 at the upper surface 122 of the glass cover 120 as the signal light 74, and the other part The illuminating light 84 is transmitted in the finger 50. Among them, the signal light 72 and the signal light 74 combine the signal light 70 and transmit it in the direction of the image sensor 210.

The light intensity and the ratio of the signal light 72 and the signal light 74 sensed by the image sensor 210 are related to the reflectance caused by the refractive index of the finger 50 and the glass cover 120. Fig. 3 is a distribution curve of the reflectance and transmittance of the illuminating light at the interface between the finger and the glass cover of Fig. 1 with respect to the incident angle of the interface, where R _{p is} the reflectance of the interface to the illuminating light 62 with respect to the incident angle _{R s is} the distribution curve of the reflectance of the interface to the illumination light 64 with respect to the angle of incidence, T _{p is} the distribution curve of the interface’s transmittance of the illumination light 62 with respect to the angle of incidence, and T _{s is the} interface control The distribution curve of the transmittance of the bright light 64 with respect to the incident angle. Among them, T _p =1-R _p , and T _s =1-R _s . It can be seen from FIG. 3 that the light intensity difference between the signal light 72 (P polarized light) and the signal light 74 (S polarized light) corresponding to a larger incident angle is greater. Since the image sensor 210 receives the signal light 70 reflected by the illumination light 60 with a larger incident angle at the outer ring, the signal light 72 (P polarized light) and the signal light at the outer ring are sensed The greater the difference in light intensity of 74 (S-polarized light).

4A is a comparison diagram of the fingerprint image sensed by the image sensor of FIG. 1 and the area of the P-polarized light and S-polarized light it receives. Please refer to Figure 1, Figure 2A, Figure 2B and Figure 4A. In Figure 4A, the image brightness in the area where P is mainly contributed by the signal light 72 (P polarized light), and the image brightness in the area where S is mainly contributed by the signal light 74 (S-polarized light), and the image brightness of the area where S+P is located is mainly contributed by the signal light 72 (P-polarized light) and the signal light 74 (S-polarized light). The area where P is located because there is a lot of penetrating light, so the contrast of the fingerprint image is stronger; the area where S is located because there is less penetrating light, so the contrast of the fingerprint image is weak; the area where P is located because there is less reflected light, so the DC value of the fingerprint image value) is low, that is, the average brightness is low; because the area where S is located, the DC value of the fingerprint image is high, that is, the average brightness is high.

FIG. 4B shows the fingerprint image of the fake finger detected by the image sensor of FIG. 1. 5A is an average grayscale distribution diagram on the diagonal MN of the fingerprint image of the real finger sensed by the image sensor of FIG. 1, and FIG. 5B is the fake finger image of the fake finger sensed by the image sensor of FIG. 1 The average gray scale distribution map of the fingerprint image on the diagonal MN. The average gray scale of a certain pixel on the diagonal MN of Fig. 5A and Fig. 5B is obtained by averaging the gray scale values of several pixels near the pixel and the gray scale value of the pixel itself. And gotta. Comparing FIGS. 4A and 4B, and FIGS. 5A and 5B, it can be found that the average brightness of the fingerprint image of the real finger at the center is lower, while the average brightness near the two ends on the diagonal line M-N is higher. Conversely, the average brightness of the fingerprint image of the fake finger is higher in the center, while the average brightness near the two ends on the diagonal line M-N is lower. One of the main reasons for this phenomenon is that the refractive index of the fake finger is different from that of the real finger, which will cause the reflectivity of P-polarized light and S-polarized light to be different, resulting in different distribution curves of average brightness at different positions. Therefore, the embodiment of the present invention can take advantage of this phenomenon to generate a scheme for identifying the real finger and the fake finger, which will be described in detail in the following content.

FIG. 6 is a schematic diagram of the controller in FIG. 1 processing fingerprint images. 1 and FIG. 6, in this embodiment, the controller 230 is used to make the inner product of the grayscale value and a Haar feature on the two axes L1 and L2 of the fingerprint image in different directions. To obtain a first result. Specifically, in this embodiment, the controller first performs blurring processing on the fingerprint image, and then performs grayscale values and Haar characteristics on the two axes L1 and L2 of the blurred fingerprint image in different directions. Inner product. The blur here is, for example, mean blur or Gaussian blur. For example, the grayscale value of each pixel is averaged with the grayscale values of several pixels around the pixel. Value, and use the average value as the new grayscale value of this pixel.

In this embodiment, the Haar feature is that the middle area C1 has a first value and the side areas C2 and C3 have a function of a second value, wherein the first value is greater than the second value. For example, the first value is +1, and the second value is -1. The blurred fingerprint image has, for example, 200×200 pixels, and the first to 75th pixels from the left end of the Haar feature each have a value of, for example, -1, and the 76th to 125th pixels each have The value of is set to, for example, +1, and the value of each of the 126th to 200th pixels is set to, for example, -1. The blurred fingerprint image also has 200 pixels on the axis L1, and each pixel has its own grayscale value, and the grayscale value represents the brightness of the blurred fingerprint image. Then, the grayscale values of the 200 pixels on the axis L1 are sequentially and respectively multiplied by the value of the 200 pixels of the Haar feature (that is, -1 or +1) to obtain 200 products, Then, the 200 products are added together to obtain the value obtained after the inner product operation.

Then, the controller 230 adds the two inner product values respectively corresponding to the axis L1 and the axis L2 to obtain a first characteristic value. Comparing Fig. 5A, Fig. 5B and Fig. 6, it can be seen that the inner product value or the first characteristic value of the real finger in Fig. 5A is smaller after the gray scale values on the axes L1 and L2 are calculated with the Haar feature. The inner product value or the first feature value of the fake finger of 5B is larger, so the calculated first feature value can be used to distinguish whether the sensed finger is a real finger or a fake finger.

FIG. 7 is another schematic diagram of the controller in FIG. 1 processing fingerprint images. 1 and 7, the controller 230 is used to calculate the average gray level of a central area D2 of the fingerprint image and the respective gray level averages of the two peripheral areas D1 and D3 on both sides of the central area D2 to obtain A second result. In addition, the controller 230 is used to synthesize the first result and the second result to determine whether the fingerprint image is from a real finger or a fake finger.

Specifically, the average gray level of the central area D2 is R2, and the average gray levels of the two peripheral areas D1 and D3 are R1 and R3, respectively. The controller 230 is used to perform arithmetic operations on R1, R2, and R3 to obtain a The second characteristic value. In this embodiment, the central area D2 and the two peripheral areas D1 and D3 are arranged on the diagonal of the fingerprint image, and the direction of the diagonal can be determined according to the direction of the penetration axis of the linear polarizer 116. That is, the direction with the greater difference between the second feature value of the real finger and the fake finger is selected as the direction of the diagonal. In one embodiment, the above-mentioned arithmetic operation is, for example, (R2-R1)+(R2-R3), or the above-mentioned arithmetic operation is, for example, R2-R1-R3. Comparing FIG. 5A, FIG. 5B, and FIG. The second characteristic value obtained by these two arithmetic operations is that the second characteristic value of the real finger is smaller, while the second characteristic value of the fake finger is larger, so the calculated second characteristic value can be used to distinguish What is sensed is a real finger or a fake finger.

FIG. 8 is a schematic diagram of the controller in FIG. 1 processing the first characteristic value and the second characteristic value of the fingerprint image. 1 and 8, the controller 230 is used to determine whether a two-dimensional coordinate formed by the first characteristic value and the second characteristic value (such as the coordinate in the coordinate plane of FIG. 8) falls in a predetermined area F1 Or F2 (for example, whether it falls within the elliptical area of the preset area F1, or whether it falls within the elliptical area of the preset area F2), and the selection of the preset area F1, the preset area F2 or other areas can be based on the experiment It is decided by the case of real finger and fake finger. If the two-dimensional coordinates fall within the predetermined area F1 or F2, the controller 230 determines that the fingerprint image is from a real finger. If the two-dimensional coordinates fall outside the preset area F1 or F2, the controller 230 determines that the fingerprint image is from a fake finger. In this way, the under-screen fingerprint sensing device 100 of this embodiment can achieve an anti-spoofing effect in fingerprint sensing, thereby enhancing the security of the user's personal data.

In the above embodiment, the real finger and the fake finger are judged based on the result of combining the first feature value and the second feature value. However, in other embodiments, the real finger and the fake finger can also be judged based on the first feature value alone, or the real finger and the fake finger can be judged based on the second feature value alone. For example, the controller 230 may only calculate the first characteristic value, and determine whether the first characteristic value falls within a preset range. If the first feature value falls within the preset range, it is determined that the fingerprint image is from a real finger; if the first feature value falls outside the preset range, it is determined that the fingerprint image is from a fake finger. Alternatively, the controller 230 may only calculate the second characteristic value and determine whether the second characteristic value falls within a preset range. If the second feature value falls within the preset range, it is determined that the fingerprint image is from a real finger; if the second feature value falls outside the preset range, it is determined that the fingerprint image is from a fake finger.

In one embodiment, the controller 230 is, for example, a central processing unit (CPU), a microprocessor (microprocessor), a digital signal processor (DSP), a programmable controller, and a programmable controller. Logic device (programmable logic device, PLD) or other similar devices or combinations of these devices are not restricted by the creation of this new model. In addition, in one embodiment, each function of the controller 230 can be implemented as a plurality of program codes. These codes are stored in a memory, and the controller 230 executes these codes. Alternatively, in an embodiment, each function of the controller 230 may be implemented as one or more circuits. The present invention does not limit the use of software or hardware to implement the functions of the controller 230.

To sum up, in the under-screen fingerprint sensing device of the inventive embodiment of the present invention, the controller makes the inner product of the grayscale values on the two axes of the fingerprint image in different directions and a Haar feature, and/ Or calculate the average gray level of the central area of the fingerprint image and the respective average gray levels of the two peripheral areas on both sides of the central area, and determine whether the fingerprint image comes from a real finger or a fake finger. Therefore, the under-screen fingerprint sensing device of the inventive embodiment of the present invention can achieve the effect of anti-spoofing in fingerprint sensing, thereby improving the security of the user's personal data.

50: finger 60, 62, 64, 82, 84: Illumination light 70, 72, 74: signal light 100: electronic device 105: display 112: organic light-emitting diode display panel 114: Phase retardation film 116: Linear polarizer 120: glass cover 122: upper surface 200: Under-screen fingerprint sensor 210: image sensor 220: lens 230: Controller C1: Middle area C2, C3: Areas on both sides D2: Central area D1, D3: surrounding area F1, F2: preset area K0: Polarization direction K1: first polarization direction K2: second polarization direction L1, L2: axis

FIG. 1 is a schematic cross-sectional view of an electronic device according to an embodiment of the new creation. FIG. 2A illustrates a situation in which the illumination light with the P polarization direction in FIG. 1 is reflected by a finger. FIG. 2B illustrates a situation in which the illumination light with the S polarization direction in FIG. 1 is reflected by the finger. 3 is a distribution curve of the reflectance and transmittance of the illuminating light at the interface of the finger and the glass cover of FIG. 1 with respect to the incident angle of the interface. 4A is a comparison diagram of the fingerprint image sensed by the image sensor of FIG. 1 and the area of the P-polarized light and S-polarized light it receives. FIG. 4B shows the fingerprint image of the fake finger detected by the image sensor of FIG. 1. FIG. 5A is an average gray scale distribution diagram of a fingerprint image of a real finger sensed by the image sensor of FIG. 1 on a diagonal line M-N. FIG. 5B is an average gray scale distribution diagram of the fingerprint image of the fake finger sensed by the image sensor of FIG. 1 on the diagonal line M-N. FIG. 6 is a schematic diagram of the controller in FIG. 1 processing fingerprint images. FIG. 7 is another schematic diagram of the controller in FIG. 1 processing fingerprint images. FIG. 8 is a schematic diagram of the controller in FIG. 1 processing the first characteristic value and the second characteristic value of the fingerprint image.

50: finger

60: Illumination light

70: Signal Light

100: electronic device

105: display

112: organic light-emitting diode display panel

114: Phase retardation film

116: Linear polarizer

120: glass cover

122: upper surface

200: Under-screen fingerprint sensor

210: image sensor

220: lens

230: Controller

K0: Polarization direction

Claims (20)

An under-screen fingerprint sensing device for matching with a display, the display emits an illuminating light, the illuminating light is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a fingerprint carrying the finger A signal light of information, the under-screen fingerprint sensing device includes: An image sensor disposed under the display, wherein the signal light penetrates the display to form a fingerprint image on the image sensor; and A controller, electrically connected to the image sensor, processes the fingerprint image sensed by the image sensor, and internalizes the grayscale values on the two axes of the fingerprint image in different directions and a Haar feature To determine whether the fingerprint image is from a real finger or a fake finger. The under-screen fingerprint sensing device according to claim 1, wherein the controller first performs a blurring process on the fingerprint image, and then calculates the gray scales on the two different axes of the blurred fingerprint image The inner product of the value and the Haar characteristic. The under-screen fingerprint sensing device according to claim 2, wherein the controller adds two inner product values corresponding to axes in two different directions, and determines whether the added value falls within a preset value Within the range, the controller reflects that the added value falls within the preset range and determines that the fingerprint image is from a real finger, and the controller reflects that the added value falls within the preset range Outside the range, it is determined that the fingerprint image is from a fake finger. The under-screen fingerprint sensing device according to claim 1, wherein the Haar feature is a function of a first value in the middle area and a second value in the areas on both sides, wherein the first value is greater than the second value . The under-screen fingerprint sensing device according to claim 1, wherein the display includes: A glass cover, wherein the finger presses on the glass cover; A linear polarizer arranged between the glass cover and the image sensor; A phase retardation film disposed between the linear polarizer and the image sensor; and An organic light emitting diode display panel is arranged between the phase retardation film and the image sensor. The under-screen fingerprint sensor according to claim 1, further comprising a lens arranged on the path of the signal light and located between the display and the image sensor. An under-screen fingerprint sensing device for matching with a display, the display emits an illuminating light, the illuminating light is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a fingerprint carrying the finger A signal light of information, the under-screen fingerprint sensing device includes: An image sensor disposed under the display, wherein the signal light penetrates the display to form a fingerprint image on the image sensor; and A controller, electrically connected to the image sensor, processes the fingerprint image sensed by the image sensor, and calculates the average gray level of a central area of the fingerprint image and two peripheral edges on both sides of the central area The average value of the respective gray levels of the area, and by this, it can be judged whether the fingerprint image is from a real finger or a fake finger. The under-screen fingerprint sensing device according to claim 7, wherein the central area and the two peripheral areas are arranged on a diagonal of the fingerprint image. The under-screen fingerprint sensing device according to claim 7, wherein the average gray level of the central area is R2, and the average gray levels of the two peripheral areas are R1 and R3, respectively, and the controller is used for comparing R1 and R2. , R3 performs arithmetic operations to obtain a feature value, and determines whether the feature value falls within a preset range, the controller responds that the feature value falls within the preset range and determines that the fingerprint image is from a true Finger, and the controller determines that the fingerprint image is from a fake finger in response to the characteristic value falling outside the preset range. The under-screen fingerprint sensing device according to claim 9, wherein the arithmetic operation is (R2-R1)+(R2-R3), or the arithmetic operation is R2-R1-R3. The under-screen fingerprint sensing device according to claim 7, wherein the display includes: A glass cover, wherein the finger presses on the glass cover; A linear polarizer arranged between the glass cover and the image sensor; A phase retardation film disposed between the linear polarizer and the image sensor; and An organic light emitting diode display panel is arranged between the phase retardation film and the image sensor. The under-screen fingerprint sensing device according to claim 7, further comprising a lens arranged on the path of the signal light and located between the display and the image sensor. An under-screen fingerprint sensing device for matching with a display, the display emits an illuminating light, the illuminating light is transmitted to a finger pressed on the display, and the finger reflects the illuminating light into a fingerprint carrying the finger A signal light of information, the under-screen fingerprint sensing device includes: An image sensor disposed under the display, wherein the signal light penetrates the display to form a fingerprint image on the image sensor; and A controller, electrically connected to the image sensor, processes the fingerprint image sensed by the image sensor, and internalizes the grayscale values on the two axes of the fingerprint image in different directions and a Haar feature To obtain a first result. The controller is used to calculate the average gray level of a central area of the fingerprint image and the average gray levels of the two peripheral areas on both sides of the central area to obtain a second As a result, the controller is used to synthesize the first result and the second result to determine whether the fingerprint image is from a real finger or a fake finger. The under-screen fingerprint sensing device according to claim 13, wherein the controller is used to first blur the fingerprint image, and then perform the blurring of the gray on the two different axes of the blurred fingerprint image. The order value is the inner product of the Haar characteristic. The under-screen fingerprint sensing device according to claim 14, wherein the controller adds two inner product values corresponding to axes in two different directions to obtain a first characteristic value, and the gray in the central area The average value of the order is R2, and the average values of the gray levels of the two peripheral areas are R1 and R3 respectively. The controller is used to perform arithmetic operations on R1, R2, and R3 to obtain a second characteristic value. The controller is used to determine the first characteristic value. Whether a two-dimensional coordinate formed by a feature value and the second feature value falls within a preset area, the controller responds to whether the two-dimensional coordinate falls within the preset area and determines that the fingerprint image is from a real Finger, and the controller determines that the fingerprint image is from a fake finger in response to the two-dimensional coordinates falling outside the predetermined area. The under-screen fingerprint sensing device according to claim 15, wherein the Haar feature is a function in which the middle area has a first value and the side areas have a second value, wherein the first value is greater than the second value . The under-screen fingerprint sensing device according to claim 15, wherein the arithmetic operation is (R2-R1)+(R2-R3), or the arithmetic operation is R2-R1-R3. The under-screen fingerprint sensing device according to claim 13, wherein the central area and the two peripheral areas are arranged on a diagonal of the fingerprint image. The under-screen fingerprint sensing device according to claim 13, wherein the display includes: A glass cover, wherein the finger presses on the glass cover; A linear polarizer arranged between the glass cover and the image sensor; A phase retardation film disposed between the linear polarizer and the image sensor; and An organic light emitting diode display panel is arranged between the phase retardation film and the image sensor. The under-screen fingerprint sensing device according to claim 13, further comprising a lens arranged on the path of the signal light and located between the display and the image sensor.

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