CN210142330U

CN210142330U - Fingerprint identification device and terminal equipment

Info

Publication number: CN210142330U
Application number: CN201921022138.6U
Authority: CN
Inventors: 姚国峰; 沈健
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2018-09-25
Filing date: 2018-09-25
Publication date: 2020-03-13
Anticipated expiration: 2028-09-25
Also published as: CN209168144U

Abstract

A fingerprint identification device and a terminal device, the fingerprint identification device comprises: an optical sensor comprising a pixel array, wherein the pixel array comprises a plurality of first type pixels and at least one second type pixel, the plurality of first type pixels and the at least one second type pixel being configured to receive an optical signal from a target; the color filter layer or the polaroid is arranged above the at least one second-type pixel point; the intensity of the optical signal received by the at least one second-type pixel point and the intensity of the optical signal received by the at least one first-type pixel point adjacent to the at least one second-type pixel point are used for determining whether the target is a real finger.

Description

Fingerprint identification device and terminal equipment

The application is a divisional application of the utility model with the application date of 2018, 9 and 25, the application number of 201821567445.8 and the name of fingerprint identification device, method and terminal equipment.

Technical Field

The present application relates to the field of optical fingerprint technology, and more particularly, to a fingerprint identification device and a terminal device.

Background

The application of the optical fingerprint recognition device brings safe and convenient user experience to users, but counterfeit fingerprints such as fingerprint molds, printed fingerprint images and the like manufactured by artificial materials (e.g., silica gel, white gel and the like) are a potential safety hazard in fingerprint application. Therefore, how to identify the authenticity of the fingerprint collected by the optical fingerprint identification device to improve the security of fingerprint identification is an urgent problem to be solved.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides a fingerprint identification device and terminal equipment, which can identify the authenticity of a fingerprint, thereby improving the safety of fingerprint identification.

In a first aspect, a fingerprint identification device is provided, which includes:

an optical sensor comprising a pixel array, wherein the pixel array comprises a plurality of first type pixels and at least one second type pixel, the plurality of first type pixels and the at least one second type pixel being configured to receive an optical signal from a target; the color filter layer or the polaroid is arranged above the at least one second-type pixel point; the intensity of the optical signal received by the at least one second-type pixel point and the intensity of the optical signal received by the at least one first-type pixel point adjacent to the at least one second-type pixel point are used for determining whether the target is a real finger.

Optionally, the color filter layer is a color filter material, and a wavelength band range of the color filter material includes only a portion of a wavelength band range of the optical signal for fingerprint identification.

Optionally, the color filter material is a green filter material, a blue filter material, or a red filter material.

Optionally, the light signals received by the second type of pixel points and the adjacent first type of pixel points are both from fingerprint ridges or both from fingerprint valleys.

Optionally, a light-transmitting material is disposed above the plurality of first-type pixels.

Optionally, the fingerprint identification device further includes:

the processor is used for determining the relative light intensity of each second-class pixel point according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by the adjacent at least one first-class pixel point; and determining whether the target is a real finger or not according to the relative light intensity and the relative light intensity range of each second-class pixel point.

Optionally, the processor is specifically configured to: and determining at least one ratio of the intensity of the optical signal received by each second-type pixel point to the intensity of the optical signal received by the adjacent at least one first-type pixel point as the relative light intensity of each second-type pixel point.

Optionally, the processor is further configured to: determining the number of second-class pixel points with relative light intensity within the relative light intensity range; and determining whether the target is a real finger or not according to the number.

Optionally, the processor is further configured to: if the number is larger than or equal to a specific number threshold value, or the proportion of the number to the total number of the second type pixel points is larger than or equal to a specific proportion threshold value, determining that the target is a real finger; or if the number is smaller than the specific number threshold, or the proportion of the number to the total number of the second type pixel points is smaller than the specific proportion threshold, determining that the target is a fake finger.

Optionally, the processor is further configured to: and determining the specific proportion threshold or the specific quantity threshold according to the security level of the operation triggering fingerprint identification and a first corresponding relation, wherein the first corresponding relation is the corresponding relation between the security level and the proportion threshold or the specific quantity threshold.

Optionally, in the first corresponding relationship, a first security level corresponds to a first proportion threshold or a first quantity threshold, and a second security level corresponds to a second proportion threshold or a second quantity threshold, where the first security level is higher than the second security level, the first proportion threshold is greater than the second proportion threshold, and the first quantity threshold is greater than the second quantity threshold.

Optionally, the processor is further configured to: and determining the relative light intensity range according to the safety level of the operation for triggering fingerprint identification and a second corresponding relationship, wherein the second corresponding relationship is the corresponding relationship between the safety level and the relative light intensity range.

Optionally, in the second corresponding relationship, the first safety level corresponds to a first light intensity range, and the second safety level corresponds to a second light intensity range, where the first safety level is higher than the second safety level, and a difference between an upper limit and a lower limit of the first light intensity range is smaller than a difference between an upper limit and a lower limit of the second light intensity range.

Optionally, the processor is further configured to: and determining the relative light intensity range according to the finger position from which the optical signal received by the second type pixel point comes, wherein the fingerprint ridge and the fingerprint valley respectively correspond to different relative light intensity ranges.

Optionally, the processor is further configured to: and determining the relative light intensity range according to the intensity of the light signals from the real finger, which are collected by the plurality of first-type pixel points and the at least one second-type pixel point for multiple times.

Optionally, the processor is further configured to: and determining that the fingerprint authentication is successful under the condition that the fingerprint information of the target is matched with the prestored fingerprint information of the target and the target is a real finger.

Optionally, the fingerprint identification device further includes: an optical assembly disposed above the pixel array for directing light signals reflected from a surface of the target to the pixel array.

Optionally, the optical assembly includes a filter layer for filtering ambient light entering the pixel array and a light guide layer for guiding light signals reflected from the surface of the target to the pixel array.

Optionally, the light guiding layer comprises at least one of: a lens layer, a collimator layer, or an aperture array layer.

Optionally, the at least one second-type pixel point is arranged in the center of the pixel array in a cross shape, a rectangular shape or a meter shape.

In a second aspect, a fingerprint identification method is provided, which is applied to a fingerprint identification apparatus including an optical sensor, where the optical sensor includes a pixel array including a plurality of first-type pixel points and at least one second-type pixel point, and a color filter layer or a polarizer is disposed above the at least one second-type pixel point, the method includes: acquiring optical signals from a target received by the plurality of first-class pixel points and the at least one second-class pixel point; and determining whether the target is a real finger or not according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by at least one first-class pixel point adjacent to each second-class pixel point.

Optionally, the determining whether the target is a real finger according to the intensity of the optical signal received by each second-type pixel point and the intensity of the optical signal received by at least one first-type pixel point adjacent to each second-type pixel point includes: determining the relative light intensity of each second-class pixel point according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by the at least one adjacent first-class pixel point; and determining whether the target is a real finger or not according to the relative light intensity and the relative light intensity range of each second-class pixel point.

Optionally, the determining the relative light intensity of each second-class pixel according to the intensity of the light signal received by each second-class pixel and the intensity of the light signal received by the at least one adjacent first-class pixel includes: and determining at least one ratio of the intensity of the optical signal received by each second-type pixel point to the intensity of the optical signal received by the adjacent at least one first-type pixel point as the relative light intensity of each second-type pixel point.

Optionally, the determining whether the target is a real finger according to the relative light intensity and the relative light intensity range of each second-type pixel point includes: determining the number of second-class pixel points with relative light intensity within the relative light intensity range; and determining whether the target is a real finger or not according to the number.

Optionally, the determining whether the target is a real finger according to the number includes:

if the number is larger than or equal to a specific number threshold value, or the proportion of the number to the total number of the second type pixel points is larger than or equal to a specific proportion threshold value, determining that the target is a real finger; or

And if the number is smaller than the specific number threshold value, or the proportion of the number to the total number of the second type pixel points is smaller than the specific proportion threshold value, determining that the target is a fake finger.

Optionally, the method further comprises: and determining the specific proportion threshold or the specific quantity threshold according to the security level of the operation triggering fingerprint identification and a first corresponding relation, wherein the first corresponding relation is the corresponding relation between the security level and the proportion threshold or the specific quantity threshold.

Optionally, the method further comprises: and determining the relative light intensity range according to the safety level of the operation for triggering fingerprint identification and a second corresponding relationship, wherein the second corresponding relationship is the corresponding relationship between the safety level and the relative light intensity range.

Optionally, the method further comprises: and determining the relative light intensity range according to the finger position from which the optical signal received by the second type pixel point comes, wherein the fingerprint ridge and the fingerprint valley respectively correspond to different relative light intensity ranges.

Optionally, the method further comprises: and determining the relative light intensity range according to the intensity of the light signals from the real finger, which are collected by the plurality of first-type pixel points and the at least one second-type pixel point for multiple times.

Optionally, the method further comprises: and determining that the fingerprint authentication is successful under the condition that the fingerprint information of the target is matched with the prestored fingerprint information of the target and the target is a real finger.

In a third aspect, a chip is provided, where the chip includes an input/output interface, at least one processor, at least one memory, and a bus, where the at least one memory is used to store instructions, and the at least one processor is used to call the instructions in the at least one memory to execute the second aspect or the method in any possible implementation manner of the second aspect.

In a fourth aspect, a terminal device is provided, which includes the fingerprint identification apparatus as in the first aspect or any possible implementation manner of the first aspect.

Optionally, the terminal device further includes: and the display screen is arranged above the fingerprint identification device.

In a fifth aspect, a terminal device is provided, which includes a fingerprint recognition apparatus and a processor. The processor and the fingerprint identification device communicate with each other via an internal connection path, and control and/or data signals are transmitted, so that the terminal device performs the method of the second aspect or any possible implementation manner of the second aspect.

A sixth aspect provides a computer readable medium for storing a computer program comprising instructions for carrying out the second aspect or any of its possible implementations.

In a seventh aspect, there is provided a computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method of fingerprint identification of the second aspect or any possible implementation manner of the second aspect.

In particular, the computer program product may be run on the terminal device of the fifth aspect described above.

Based on above-mentioned technical scheme, through set up certain quantity of second type pixel in fingerprint identification device's pixel array, detect the intensity of light signal through second type pixel and first type pixel, wherein, the intensity of the light signal that second type pixel detected is less than the intensity of the light signal that adjacent first type pixel detected, because to different materials, this intensity difference is different, consequently, according to the intensity difference of the light signal that second type pixel and first type pixel detected, can confirm the true and false of fingerprint, and then can promote fingerprint identification's security.

Drawings

Fig. 1 is a schematic structural diagram of a terminal device to which the embodiment of the present application is applied.

Fig. 2 is a schematic structural diagram of a fingerprint recognition device according to an embodiment of the present application.

Fig. 3 is a cross-sectional view of a fingerprint recognition device according to an embodiment of the present application.

FIG. 4 is a schematic flow chart diagram of a method of fingerprint identification according to an embodiment of the present application.

FIG. 5 is a schematic flow chart diagram of a fingerprint entry process according to another embodiment of the present application.

Fig. 6 is an overall flowchart of a method of fingerprint recognition according to an embodiment of the present application.

Fig. 7 is a schematic block diagram of a terminal device according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

It should be understood that the embodiments of the present application can be applied to optical fingerprint systems, including but not limited to optical fingerprint identification systems and medical diagnostic products based on optical fingerprint imaging, and the embodiments of the present application are only described by way of example, but should not be construed as limiting the embodiments of the present application, and the embodiments of the present application are also applicable to other systems using optical imaging technology, etc.

As a common application scenario, the optical fingerprint system provided by the embodiment of the application can be applied to smart phones, tablet computers and other mobile terminals or other terminal devices with display screens; more specifically, in the terminal device described above, the fingerprint recognition device may be embodied as an optical fingerprint device, which may be disposed in a partial area or an entire area below the display screen, thereby forming an Under-screen (Under-display) optical fingerprint system.

As shown in fig. 1, which is a schematic structural diagram of a terminal device to which the embodiment of the present application is applicable, the terminal device 10 includes a display screen 120 and an optical fingerprint device 130, where the optical fingerprint device 130 is disposed in a local area below the display screen 120. The optical fingerprint device 130 includes a sensing array having a plurality of optical sensing units, and the sensing array is located in a fingerprint detection area 103 of the optical fingerprint device 130. As shown in fig. 1, the fingerprint detection area 103 is located in the display area of the display screen 120, so that when a user needs to unlock or otherwise verify the fingerprint of the terminal device, the user only needs to press a finger on the fingerprint detection area 103 located on the display screen 120, so as to implement fingerprint input. Since fingerprint detection can be implemented in the screen, the terminal device 10 adopting the above structure does not need to reserve a special space on the front surface thereof to set a fingerprint key (such as a Home key), so that a full-screen scheme can be adopted, that is, the display area of the display screen 120 can be substantially extended to the front surface of the whole terminal device 10.

As an alternative implementation, as shown in fig. 1, the optical fingerprint device 130 includes a light detection portion 134 and an optical component 132, where the light detection portion 134 includes the sensing array and a reading circuit and other auxiliary circuits electrically connected to the sensing array, which can be fabricated on a chip (Die) by a semiconductor process, and the sensing array is specifically a Photo detector (photodetector) array, which includes a plurality of photodetectors distributed in an array, and the photodetectors can be used as the optical sensing units as described above; the optical assembly 132 may be disposed above the sensing array of the light detecting portion 134, and may specifically include a Filter layer (Filter) for filtering out ambient light penetrating through the finger, a light guide layer for guiding reflected light reflected from the surface of the finger to the sensing array for optical detection, and other optical elements.

In a specific implementation, the optical component 132 and the light detection portion 134 can be packaged in the same optical fingerprint module. The light guide layer can be specifically a Collimator (collimater) layer or a Lens (Lens) layer which is manufactured on a semiconductor silicon wafer, the light guide layer is provided with a plurality of collimation units or Lens units, the collimation units can be specifically small holes, in reflected light reflected back from a finger, light which is vertically incident to the collimation units can penetrate through and be received by an optical sensing unit below the collimation units, and light which is obliquely incident is attenuated in the collimation units through multiple reflections, so that each optical sensing unit basically only can receive the reflected light reflected back by fingerprint grains right above the optical sensing unit, and the sensing array can detect a fingerprint image of the finger.

In the optical fingerprint device 130, each collimating unit or lens unit may correspond to one of the optical sensing units of the sensing array; alternatively, the collimator units or the lens units and the optical sensing units of the sensing array may also use a non-one-to-one correspondence relationship to reduce moire interference, for example, one optical sensing unit may correspond to a plurality of collimating units or lens units, or the collimating units or lens units may also use an irregular arrangement manner; the irregular arrangement of the collimating units or the lens units can be used for correcting the reflected light rays detected by each sensing unit through a later software algorithm.

As an alternative embodiment, the display screen 120 may adopt a display screen having a self-Light Emitting display unit, such as an Organic Light-Emitting Diode (OLED) display screen or a Micro-LED (Micro-LED) display screen. Taking an OLED display screen as an example, the optical fingerprint device 130 may use the display unit (i.e., OLED light source) of the OLED display screen 120 located in the fingerprint detection area 103 as an excitation light source for optical fingerprint detection. When the finger 140 is pressed against the fingerprint detection area 103, the display 120 emits a beam of light 111 towards the target finger 140 above the fingerprint detection area 103, which light 111 is reflected at the surface of the finger 140 to form reflected light. Because ridges (ridges) and valleys (vally) of the fingerprint have different light reflection capabilities, reflected light 151 from the ridges and the peaks and valleys 152 from the fingerprint have different light intensities, and after passing through the optical assembly 132, the reflected light is received by the sensor array 134 in the optical fingerprint device 130 and converted into corresponding electric signals, i.e., fingerprint detection signals; fingerprint image data can be obtained based on the fingerprint detection signal, and fingerprint matching verification can be further performed, so that an optical fingerprint identification function is realized in the terminal device 10.

In other alternative implementations, the display screen 120 may also be a non-self-luminous display screen, such as a liquid crystal display screen that uses a backlight; in this case, the optical detection device 130 cannot use the display unit of the display screen 120 as an excitation light source, so that it is necessary to integrate the excitation light source inside the optical detection device 130 or arrange the excitation light source outside the optical detection device 130 to realize optical fingerprint detection, and the detection principle is consistent with the above description.

It should be understood that in a specific implementation, the terminal device 10 further includes a transparent protective cover plate, which may be a glass cover plate or a sapphire cover plate, positioned above the display screen 120 and covering the front surface of the terminal device 10. Because, in the present embodiment, the pressing of the finger on the display screen 120 actually means pressing on the cover plate above the display screen 120 or the surface of the protective layer covering the cover plate.

It should also be understood that, the technical solution of the embodiment of the present application may perform other biometric identification besides fingerprint identification, for example, palm print identification or vein identification, and the embodiment of the present application is also not limited thereto.

It should be noted that, optical fingerprint device in this application embodiment also can be called optical fingerprint identification module, fingerprint identification device, fingerprint identification module, fingerprint collection device etc. but above-mentioned term mutual replacement.

It should be understood that the reflection performance of human skin tissue to light with specific wavelength is significantly different from that of artificial materials such as silica gel, paper and adhesive tape, etc. under the influence of factors such as cortex thickness, hemoglobin concentration, melanin content, etc. of human skin tissue.

Based on this, this application embodiment provides a fingerprint identification scheme, set up certain quantity of characteristic pixel in fingerprint identification device's pixel array, wherein, to same light signal, the intensity of the light signal that characteristic pixel detected is less than the intensity of the light signal that adjacent ordinary pixel detected, detect the intensity of light signal through characteristic pixel and ordinary pixel, because to different materials, this intensity difference is different, consequently can be according to the intensity difference of the light signal that characteristic pixel and ordinary pixel detected, confirm the true and false of fingerprint, this fingerprint is whether promptly comes from the live body finger, that is to say, the fingerprint identification scheme of this application embodiment can be used for the live body to detect.

Hereinafter, the fingerprint identification device according to the embodiment of the present application will be described in detail with reference to fig. 2 to 3.

It should be noted that, for the sake of understanding, the same structures are denoted by the same reference numerals in the embodiments shown below, and detailed descriptions of the same structures are omitted for the sake of brevity.

It should be understood that the dimensions, heights, thicknesses, etc. of the various structural members in the embodiments of the present application shown below are merely illustrative and should not limit the present application in any way.

Fig. 2 is a schematic structural diagram of a fingerprint identification device 20 according to an embodiment of the present application, where the fingerprint identification device 20 includes: an optical sensor 200 and a processor 220. The optical sensor 200 includes a pixel array 210, the pixel array 210 includes a plurality of first-type pixels 211 and at least one second-type pixel 212, and a color filter layer or polarizer 221 is disposed above the at least one second-type pixel.

It should be understood that in the embodiment of the present application, the optical sensor 200 may be the light detection portion 134 in fig. 1, or a fingerprint sensor (sensor).

Optionally, in the embodiment of the present application, the fingerprint identification device 200 may further include an optical component 230, and the optical component 230 may correspond to the optical component 132 in fig. 1.

It should be understood that, in this embodiment of the present application, the first-type pixel points may be referred to as common pixel points, the setting manner of the first-type pixel points may be the same as that of pixel points in an existing pixel array, the second-type pixel points may be referred to as feature pixel points, and are used for determining whether a fingerprint is true or false, the setting manner of the second-type pixel points is different from that of the existing pixel points, and a material or a structure capable of reducing intensity of an optical signal entering the feature pixel points, such as a color filter layer or a polarizer, is disposed above the second-type pixel.

It should be noted that the positions, the numbers, and the distribution of the first-type pixel points 211 and the second-type pixel points 212 in fig. 2 are only examples, and should not limit any embodiment of the present application, and the present application may also be adjusted according to actual requirements.

In some alternative arrangements, the second type pixels 212 may be disposed in a cross shape, a rectangular shape or a meter shape at the center of the pixel array 210.

In the embodiment of the present application, the color filter layer 221 may filter the optical signals, which only allows the optical signals within a specific wavelength range to pass through, for example, the color filter layer 221 may be a green filter material, which only allows the optical signals in a green light band to pass through, so that after the optical signals pass through the color filter layer 221, the wavelength band of the optical signals becomes narrow, the overall light intensity decreases, that is, the intensity of the optical signals entering the second type of pixels decreases. The polarizing film can be used for changing the polarization direction of the optical signal, so that the polarizing film can also play a role in reducing the intensity of the optical signal entering the second type pixel point.

It should be understood that, in the embodiment of the present application, other structures may be disposed above the second type of pixels, or other materials may be coated, as long as the purpose of reducing the intensity of the optical signal entering the second type of pixels is achieved, and the embodiment of the present application does not limit this. In the following, an example of disposing the color filter layer 221 above the second type pixels 212 is described, but the present invention should not be limited thereto.

It should be noted that, in the embodiment of the present application, the wavelength band of the emitted light of the light source for fingerprint detection needs to include the wavelength band of the color filter material, and at least some other wavelength bands besides this wavelength band range, that is, the wavelength band of the color filter material only includes some of the wavelength bands of the emitted light. Therefore, the reflected light enters the color filter layer after being reflected on the surface of the target, a part of optical signals are filtered after passing through the color filter layer, and meanwhile, a part of optical signals are allowed to pass through so as to determine the relative light intensity of the second type of pixel points.

For example, if the light source emits white light, the color filter material may be a green filter material that only allows a green light band to pass, or may also be a blue filter material that only allows a blue light band to pass, or may also be a cyan filter material that simultaneously allows green light and blue light bands to pass, as long as the color filter material can filter optical signals of a partial band and simultaneously allows optical signals of other bands to pass, which is not limited in the embodiment of the present application.

Optionally, in this embodiment of the present application, the light source for fingerprint detection may be a self-luminous light source from a display screen, or may also be an excitation light source integrated inside the fingerprint identification device or other external excitation light sources, which is not limited in this embodiment of the present application.

Optionally, in some embodiments, a light-transmitting material 222 may be disposed above the first-type pixels 211, so that the intensity of the light signal entering the first-type pixels 211 is not affected or is less affected. Alternatively, in other embodiments, no light-transmitting material may be disposed above the first type pixels 211, i.e., air may be disposed between the first type pixels and the optical component 230 above the first type pixels.

Then, the optical signal reflected from the target surface respectively reaches the first type pixel point 211 and the second type pixel point 212 after passing through the transparent material 222 and the color filter layer 221, and due to the different optical properties of the transparent material 222 and the color filter layer 221, the intensity of the reflected light detected by the second type pixel point 212 and the adjacent first type pixel point 211 has a certain difference, and for different materials (for example, skin tissue and artificial material), the intensity difference is obviously different, so that based on the intensity difference, it can be determined whether the fingerprint image collected by the fingerprint identification device is from a real finger.

It should be understood that, in this embodiment of the present application, the first type pixel 211 adjacent to the second type pixel 212 may include at least one of the first type pixels 211 located above, below, to the left, or to the right of the second type pixel 212, or a circle may be drawn with a specific radius by taking the second type pixel 212 as a center, and the first type pixel 211 located in the circle is determined as the first type pixel adjacent to the second type pixel 212, or the adjacent first type pixel may also be determined according to other manners, which is not limited in this embodiment of the present application.

It should be noted that the second-type pixel point and the first-type pixel point adjacent to the second-type pixel point are the same-type pixel points, where the same-type pixel point may mean that the light signals received by the second-type pixel point and the adjacent first-type pixel point are both from a fingerprint ridge or both from a fingerprint valley, that is, the types of the fingerprint positions from which the light signals are received are the same.

In summary, the main difference between the second type of pixel points and the adjacent first type of pixel points lies in that the filtering material disposed above the second type of pixel points is different, that is, a color filtering layer or a polarizing film is disposed above the second type of pixel points, while the first type of pixel points are disposed above the transparent material or without any material, and the characteristics in other aspects are substantially the same, for example, the collected light signals all come from a fingerprint ridge or all come from a fingerprint valley, and the positions in the pixel array are adjacent, so that the environments where the collected light signals are located can be considered to be the same or similar, in other words, the influence of the environmental factors on the collected light signals is the same or similar, then, the ratio of the intensity of the light signals received by the second type of pixel points to the intensity of the light signals received by the adjacent first type of pixel points is calculated, so that the ratio for eliminating the influence of the environmental factors can significantly reflect the optical characteristics of the material of the target object, furthermore, whether the target object is a real finger or not is determined according to the ratio, so that the accuracy of living body detection can be improved.

It should be understood that, in this embodiment of the present application, the fingerprint information of the target object may not be determined by using the sampling value of the second type pixel, in this case, the sampling value of the second type pixel may be determined according to the sampling value of the adjacent first type pixel, for example, the sampling value of the adjacent first type pixel is interpolated or fitted to obtain the sampling value of the second type pixel.

Optionally, in this application embodiment, the sampling value of this second type of pixel point also can be used to determine the fingerprint information of the target object, because of the optical imaging principle, the pixel point of the central position of the fingerprint detection area usually enters the saturation region in advance, and through setting the second type of pixel point at the central position of the pixel array, it can be favorable to avoiding the too early entering of the sampling value of the central position into the saturation region, thereby can promote the sampling value of the central area pixel point.

Optionally, in some embodiments, the processor 220 is specifically configured to:

determining the relative light intensity of each second-class pixel point according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by the at least one adjacent first-class pixel point;

and determining whether the target is a real finger or not according to the relative light intensity and the relative light intensity range of each second-class pixel point.

As an embodiment, the relative light intensity of the second-type pixel may be a ratio of the intensities of the optical signals received by the second-type pixel and the adjacent first-type pixel, or alternatively, a plurality of ratios between the second-type pixel and the adjacent first-type pixels may be determined, and the relative light intensity of the second-type pixel is determined according to the ratios, for example, a maximum value, a minimum value, or an average value of the ratios may be determined as the relative intensity of the second pixel.

The second-class pixel point is P2, the intensity of the detected optical signal is S2, the first-class pixel points adjacent to the second-class pixel point include P11, P12 and P13, the intensities of the detected optical signals are S11, S12 and S13 respectively, and then the relative intensity of the P2 can be any one of S2/S11, S2/S12 and S2/S13; alternatively, the relative intensity of P2 may be the maximum, minimum, or average of S2/S11, S2/S12, and S2/S13.

As another embodiment, the maximum value, the minimum value, or the average value of the intensities of the light signals received by the plurality of first-type pixel points adjacent to the second-type pixel point may be determined first, and then the ratio of the intensity of the light signal received by the second-type pixel point to the maximum value, the minimum value, or the average value of the intensities of the light signals received by the plurality of first-type pixel points adjacent to the second-type pixel point is determined as the relative light intensity of the second-type pixel point.

Following the above example, the relative intensity RS of the second type pixel point P2 may be S2/max (S11+ S12+ S13), S2/min (S11+ S12+ S13) or S2/avg (S11+ S12+ S13), where max, min, and avg respectively represent taking a maximum value, a minimum value, and an average value.

It should be understood that the above determination manner of the relative light intensity of the second-type pixel point is only an example, and the processor may also determine the relative light intensity of the second-type pixel point according to other formulas, as long as the difference between the intensity of the optical signal collected by the second-type pixel point and the intensity of the optical signal collected by the adjacent same-type first-type pixel point can be reflected, and the embodiment of the present application is not particularly limited.

Therefore, the relative light intensity of the second-type pixels can be used to represent the degree of reduction (or attenuation) of the light intensity of the second-type pixels relative to the light intensity of the light signal received by the adjacent first-type pixels. For different materials, the reduction degree has obvious difference, that is, the real finger corresponds to a specific relative light intensity range, and for artificial materials, the relative light intensity of the second type pixel point is not in the relative light intensity range, so that whether the target is the real finger or not can be determined according to whether the relative light intensity of the second type pixel point is in the relative light intensity range or not.

In an alternative implementation manner, the processor may determine the number (or matching number) of the second type pixel points with the relative light intensity within the relative light intensity range, and further determine whether the target is a real finger according to the number. For example, the processor may determine that the target is a real finger when the number is greater than a certain number threshold, otherwise, determine that the target is a fake finger; or, the processor may determine that the target is a real finger when the ratio (or called matching ratio) of the number to the total number of the second type of pixels is greater than or equal to a specific ratio threshold, otherwise, determine that the target is a fake finger.

Alternatively, in some embodiments, a security level of the operation triggering the fingerprint recognition may be set, for example, the unlocking operation of the terminal device may be set to a low security level, the payment class operation may be set to a high security level, and further, different specific number thresholds or specific proportion thresholds may be set for different security levels, that is, a first corresponding relationship between the security level and the specific number threshold or the specific proportion threshold may be determined, so that the processor may determine the specific number threshold or the specific proportion threshold according to the security level of the operation triggering the fingerprint recognition in combination with the first corresponding relationship.

For example, if the high security level corresponds to a first quantity threshold or a first proportion threshold, and the low security level corresponds to a second quantity threshold or a second proportion threshold, the first quantity threshold may be set to be greater than the second quantity threshold, and the first proportion threshold may be greater than the second proportion threshold. The fingerprint identification method has the advantages that the fingerprint identification safety is favorably improved by setting the high security level to correspond to the high matching quantity or matching proportion, the fingerprint identification Rejection Rate (FRR) is favorably reduced by setting the low security level to correspond to the low matching quantity or matching proportion, and the fingerprint identification speed is improved.

Alternatively, in some embodiments, different safety levels may be set for different relative light intensity ranges, i.e. a second correspondence between the safety level and the relative light intensity range is determined, e.g. a low safety level may be set for a wider relative light intensity range than a high safety level. For example, if a high safety level corresponds to a first light intensity range and a low safety level corresponds to a second light intensity range, the upper limit of the first light intensity range may be set smaller than the upper limit of the second light intensity range and/or the lower limit of the first light intensity range may be set larger than the lower limit of the second light intensity range. Correspond narrower relative light intensity scope through setting up high security level, be favorable to promoting fingerprint identification's security, correspond the relative light intensity scope of broad through setting up low security level, be favorable to reducing FRR, promote fingerprint identification speed.

Optionally, in some embodiments, because the reflection capacities of the fingerprint ridge and the fingerprint valley are different, the corresponding relative light intensity ranges may be configured for whether the light signal is from the fingerprint ridge or the fingerprint valley, respectively, so that the processor may determine, according to which relative light intensity range the light signal received by the second type of pixel point is from the fingerprint ridge or the fingerprint valley, whether the fingerprint is true or false.

Alternatively, the relative light intensity range in the embodiment of the present application may be obtained by collecting a large number of fingerprint samples of real fingers for training, and the following method embodiments are described in detail.

Alternatively, in this embodiment of the application, the processor may determine that fingerprint authentication is successful if fingerprint information of a target collected by the fingerprint identification device matches a registered fingerprint template of the target, and the target is a real finger, and further, may perform an operation of triggering the fingerprint identification, for example, perform an operation of unlocking a terminal or paying.

The operation principle of the fingerprint recognition device according to the embodiment of the present application will be described with reference to the transmission diagram of the optical signal shown in fig. 3.

When the target 240 is placed over a fingerprint identification region (e.g., the fingerprint detection region 103 in fig. 1), the light signals 251, 255, and 253 emitted by the display 250 reach the fingerprint ridge 241 and the fingerprint valley 242, respectively, and form reflected light 252, 256, and 254, respectively, where the reflected

light

252 and 256 are from the reflection of the fingerprint ridge 241 and the reflected light 254 is from the reflection of the fingerprint valley 242. Generally, the reflection of the light signal at the fingerprint ridge is strong, so the intensity of the reflected light signal is large, the reflection at the fingerprint valley is weak, so the intensity of the reflected light signal is small, and after the reflected

lights

254 and 256 are received by the first type pixel points 211, a fingerprint image with bright and dark contrast can be obtained.

After the reflected light 252 passes through the color filter layer 222, the signal intensity is decreased relative to the reflected light 256, and it can be determined that the ratio of the intensity of the reflected light 252 received by the second-type pixel points 212 to the intensity of the reflected light 256 received by the first-type pixel points 211 fluctuates within a specific light intensity range for a real finger, whereas for artificial materials such as silica gel, paper, or tape, the ratio is not within the light intensity range due to the difference in reflection performance from skin tissue, and therefore, it can be determined whether the target 240 is a real finger according to whether the ratio is within the light intensity range. For example, if the light intensity range is [0.65,0.75], the object 240 can be considered as a fake finger if the relative light intensities of the second-type pixels are all determined to be around 0.5.

Optionally, in this embodiment of the application, the fingerprint identification device 20 may further include a driving module and a signal reading module, the driving module and the signal reading module may be connected to the pixel array 210 through internal traces, wherein the driving module is configured to control the line-by-line scanning of the pixel array 210, the signal reading module may be configured to process a signal detected by the pixel array 210, for example, perform amplification and Analog-to-Digital conversion (ADC), and further send the processed signal to the processor 220, and optionally, the signal reading module and the processor 220 may be connected through a Flexible Printed Circuit (FPC).

The apparatus embodiments of the present application are described in detail above with reference to fig. 2-3, and the method embodiments of the present application are described in detail below with reference to fig. 4-6, it being understood that the method embodiments correspond to the apparatus embodiments and that similar descriptions may be made with reference to the apparatus embodiments.

Fig. 4 is a schematic flow chart of a method of fingerprint identification according to an embodiment of the present application, and it should be understood that the method 400 may be applied to the fingerprint identification device 20 shown in fig. 2, and in particular, the method 400 may be executed by a processor in the fingerprint identification device, as shown in fig. 4, and the method 400 includes:

s401, acquiring optical signals from a target, which are received by a plurality of first-class pixel points and at least one second-class pixel point;

s402, determining whether the target is a real finger or not according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by at least one first-class pixel point adjacent to each second-class pixel point.

Optionally, in some embodiments, S402 may specifically include:

determining the relative light intensity of each second-class pixel point according to the intensity of the optical signal received by each second-class pixel point and the intensity of the optical signal received by the at least one adjacent first-class pixel point; and determining whether the target is a real finger or not according to the relative light intensity and the relative light intensity range of each second-class pixel point.

Optionally, in some embodiments, the determining the relative light intensity of each second-type pixel according to the intensity of the light signal received by each second-type pixel and the intensity of the light signal received by the adjacent at least one first-type pixel includes:

and determining at least one ratio of the intensity of the optical signal received by each second-type pixel point to the intensity of the optical signal received by the adjacent at least one first-type pixel point as the relative light intensity of each second-type pixel point.

Optionally, in some embodiments, the determining whether the object is a real finger according to the relative light intensity and the relative light intensity range of each of the second-type pixels includes:

determining the number of second-class pixel points with relative light intensity within the relative light intensity range;

and determining whether the target is a real finger or not according to the number.

Optionally, in some embodiments, the determining whether the target is a real finger according to the number includes:

Optionally, in some embodiments, the method 400 further comprises:

and determining the specific proportion threshold or the specific quantity threshold according to the security level of the operation triggering fingerprint identification and a first corresponding relation, wherein the first corresponding relation is the corresponding relation between the security level and the proportion threshold or the specific quantity threshold.

Optionally, in some embodiments, the method further comprises:

and determining the relative light intensity range according to the safety level of the operation for triggering fingerprint identification and a second corresponding relationship, wherein the second corresponding relationship is the corresponding relationship between the safety level and the relative light intensity range.

Optionally, in some embodiments, the method 400 further comprises:

and determining the relative light intensity range according to the finger position from which the optical signal received by the second type pixel point comes, wherein the finger position comprises a fingerprint ridge and a fingerprint valley which respectively correspond to different intensity ranges.

Optionally, in some embodiments, the method 400 further comprises:

and determining the relative light intensity range according to the light signals from the plurality of real fingers collected by the plurality of first-type pixel points and the at least one second-type pixel point.

For a user who performs fingerprint identification for the first time, fingerprint information needs to be collected and input, and the process of determining the relative light intensity range can be realized in the process of inputting the fingerprint. As shown in fig. 5, the method may specifically include the following steps:

s301, light signals reflected from the finger of the user are collected for multiple times through common pixel points and characteristic pixel points in a pixel array of the fingerprint identification device, wherein the light signals collected by the common pixel points can be used for determining fingerprint information of the user, meanwhile, multiple ratios of the intensity of the light signals collected by each characteristic pixel point and the adjacent common pixel points can also be determined, and the multiple ratios can be used for determining the relative light intensity range.

Because the light signal detected by the characteristic pixel point can come from the fingerprint ridge and also can come from the fingerprint valley, the corresponding relative light intensity ranges under the two conditions can be determined.

In the embodiment of the application, a large number of real fingers can be subjected to fingerprint acquisition through common pixel points and characteristic pixel points in a pixel array of the fingerprint identification device to determine the relative light intensity range, and the large number of real fingers can be from the same user or can be from a plurality of different users.

Further, in S302, the relative light intensity range may be determined according to the plurality of ratios obtained in S301.

Optionally, the plurality of ratios may be machine-learned, or sample data of the plurality of ratios may also be trained by a convolutional neural network to determine the relative light intensity range.

After determining the fingerprint information entered by the user and the relative light intensity range, a subsequent fingerprint authentication (i.e., fingerprint identification) process will be described with reference to fig. 6. The method specifically comprises the following steps:

s510, determining a safety level according to an application scene;

specifically, the application scenario may include a terminal unlocking scenario, a payment scenario, and the like, different application scenarios may correspond to different security levels, fingerprint identification algorithms corresponding to different security levels are different, and different security levels may specifically correspond to different relative light intensity ranges, matching number thresholds, matching proportion thresholds, and the like, and the specific implementation may refer to the related description of the foregoing embodiment.

S520, the fingerprint identification device detects a fingerprint image of the target above the fingerprint identification area.

S530, whether the fingerprint image is matched with the input fingerprint image of the target is determined.

If so, executing S540, otherwise, executing S535, indicating that the fingerprint identification fails to the user, or prompting the user to perform the fingerprint input again, and the process goes to S520.

In S540, a ratio of the intensity of the optical signal received by each characteristic pixel point and the adjacent common pixel points of the same type, i.e. the relative light intensity of the second type pixel point, is calculated.

Further, in S550, the number of characteristic pixels whose ratio is within the relative light intensity range is determined according to the relative light intensity range corresponding to the security level determined in the step 510 and the matching number threshold.

In S560, it is determined whether the number reaches a matching number threshold.

If so, executing S570 to determine that the fingerprint authentication is successful, otherwise, executing S565 to indicate that the fingerprint identification fails to the user, or prompt the user to perform fingerprint input again, and the process goes to S520.

Therefore, in the embodiment of the present application, the fingerprint identification apparatus may determine that the fingerprint authentication is successful when the fingerprint information of the target matches the pre-stored fingerprint information of the target, and the target is a real finger, so as to improve the security of fingerprint identification.

It should be understood that the above fingerprint identification process is only an example, and in the embodiment of the present application, it may also be determined whether the target is a real finger, and then, in a case that the target is a real finger, it is determined whether the fingerprint information of the target matches the entered fingerprint information of the target, and in a case that the above two conditions are simultaneously met, it is determined that the fingerprint authentication is successful, and further, an operation triggering the fingerprint identification is performed, for example, an operation of unlocking the terminal or paying is performed.

It should be understood that, in the method embodiment of the present application, the sequence numbers of the above-mentioned processes do not imply an order of execution, and the order of execution of the processes should be determined by their functions and inherent logic, and should not limit the implementation process of the embodiment of the present application.

As shown in fig. 7, the present application further provides a terminal device 700, where the terminal device 700 may include a fingerprint identification apparatus 710, and the fingerprint identification apparatus 710 may be the fingerprint identification apparatus 20 in the foregoing apparatus embodiments, which can be used to execute the contents in the method embodiments in fig. 4 to fig. 6.

It should be understood that the processor of the embodiments of the present application may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor may be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

It will be appreciated that the fingerprinting of embodiments of the present application may also include memory, which may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory. The volatile Memory may be a Random Access Memory (RAM) which functions as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static random access memory (Static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), Synchronous dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous dynamic random access memory (DDR SDRAM), Enhanced Synchronous SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), and Direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

Embodiments of the present application also provide a computer-readable storage medium storing one or more programs, the one or more programs including instructions, which when executed by a portable electronic device including a plurality of application programs, enable the portable electronic device to perform the method of the embodiments shown in fig. 4 to 6.

Embodiments of the present application also provide a computer program, which includes instructions, when the computer program is executed by a computer, the computer may execute the method of the embodiments shown in fig. 4 to 6.

The embodiment of the present application further provides a chip, where the chip includes an input/output interface, at least one processor, at least one memory, and a bus, where the at least one memory is used to store instructions, and the at least one processor is used to call the instructions in the at least one memory to execute the method of the embodiment shown in fig. 4 to 6.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A fingerprint identification device is suitable for a terminal device with a display screen, and is characterized in that a fingerprint detection area of the fingerprint identification device is located in a display area of the display screen, and the fingerprint identification device comprises:

the optical sensor is arranged below a display screen of the terminal equipment and comprises a pixel array, wherein the pixel array comprises a plurality of first-class pixel points and at least one second-class pixel point, and the first-class pixel points and the at least one second-class pixel point are used for receiving optical signals from a target above the display screen;

the color filter layer is arranged above the at least one second-type pixel point to filter partial optical signals entering the at least one second-type pixel point;

the light signals received by the plurality of first-class pixel points are used for detecting the fingerprint image of the target, and the light signals received by the at least one second-class pixel point are at least used for determining whether the target is a real finger.

2. The fingerprint recognition device of claim 1, wherein the color filter layer is a color filter material, and the wavelength range of the color filter material comprises a partial wavelength range of an optical signal for fingerprint recognition.

3. The fingerprint recognition device of claim 1, wherein the color filter layer is at least one of a green filter layer, a blue filter layer, and a red filter layer.

4. The fingerprint recognition device of claim 1, wherein the light signals received by the second type of pixel points and the adjacent first type of pixel points are both from fingerprint ridges or both from fingerprint valleys.

5. The fingerprint identification device according to claim 1, wherein a transparent material is disposed above the plurality of first-type pixels, and the transparent material is optically formed differently from the color filter layer, so that the intensity of the optical signal detected by the second-type pixels and the adjacent first-type pixels is different.

6. The fingerprint recognition device of claim 5, wherein the intensity difference of the light signals detected by the second-type pixels and the adjacent first-type pixels is used to determine whether the object is a real finger.

7. The fingerprint identification device of claim 5, wherein the light transmissive material disposed over the first type of pixel comprises a layer of air.

8. The fingerprint recognition device according to any one of claims 1 to 7, further comprising:

an optical assembly disposed above the pixel array for directing light signals reflected from a surface of the target to the pixel array.

9. The fingerprint recognition device of claim 8, wherein the optical assembly comprises an optical filter layer and a light guide layer, wherein the optical filter layer is configured to filter out ambient light entering the pixel array, and the light guide layer is configured to guide light signals reflected from the surface of the object to the pixel array.

10. The fingerprint recognition device of claim 9, wherein the light guide layer comprises at least one of: a lens layer, a collimator layer, or an aperture array layer.

11. The fingerprint recognition device of claim 1, wherein the light signal from the object above the display screen is a light signal formed by at least a portion of the emitted light from the light-emitting display unit of the display screen impinging on the object above the display screen and returning through the display screen.

12. The fingerprint recognition device according to claim 1, wherein the light signal from the object above the display screen is a light signal formed by the emission light emitted by the excitation light source inside the fingerprint recognition device or the external excitation light source irradiating the object above the display screen and returning through the display screen.

13. The fingerprint recognition device according to claim 11 or 12, wherein the wavelength band range of the emitted light includes at least the wavelength band of the color filter layer.

14. The fingerprint recognition device of claim 13, wherein the emitted light is white light, and the color filter is a blue filter that allows blue light to pass, a green filter that allows green light to pass, or a cyan filter that allows both green and blue light to pass.

15. The fingerprint identification device according to claim 1, further comprising a driving module, a signal reading module and a processor, wherein the driving module and the signal reading module are connected to the pixel array through internal routing, the driving module is configured to control the pixel array to perform line-by-line scanning, and the signal reading module is configured to process the optical signal detected by the pixel array and send the processed signal to the processor.

16. The fingerprint identification device of claim 15, wherein the processor is connected to the signal reading module through a flexible circuit board, and the processor is configured to determine the relative light intensity of each second-type pixel according to the intensity of the light signal received by each second-type pixel and the intensity of the light signal received by the at least one adjacent first-type pixel; and determining whether the target is a real finger or not according to the relative light intensity and the relative light intensity range of each second-class pixel point.

17. A terminal device, comprising:

the fingerprint recognition device according to any one of claims 1 to 16; and the number of the first and second groups,

and the display screen is arranged above the fingerprint identification device.

18. The terminal device according to claim 17, wherein the display screen is a self-luminous display screen having a plurality of self-luminous display units, wherein at least a part of the self-luminous display units of the fingerprint detection area serve as an excitation light source of the fingerprint recognition apparatus, and the light signal from the object above the display screen is a light signal formed by irradiating light emitted from the at least part of the self-luminous display units to the object above the display screen and returning through the display screen.