CN109993144B - Optical fingerprint identification component and electronic equipment - Google Patents
Optical fingerprint identification component and electronic equipment Download PDFInfo
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- CN109993144B CN109993144B CN201910286341.2A CN201910286341A CN109993144B CN 109993144 B CN109993144 B CN 109993144B CN 201910286341 A CN201910286341 A CN 201910286341A CN 109993144 B CN109993144 B CN 109993144B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/10—Image acquisition
- G06V10/12—Details of acquisition arrangements; Constructional details thereof
- G06V10/14—Optical characteristics of the device performing the acquisition or on the illumination arrangements
- G06V10/145—Illumination specially adapted for pattern recognition, e.g. using gratings
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1318—Sensors therefor using electro-optical elements or layers, e.g. electroluminescent sensing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/1365—Matching; Classification
- G06V40/1376—Matching features related to ridge properties or fingerprint texture
Abstract
The application provides an optical fingerprint identification component and electronic equipment, wherein the optical fingerprint identification component comprises a substrate, an optical sensor layer and an optical structure layer, wherein the optical structure layer comprises a first structure layer and a second structure layer which are attached to each other, the refractive index of the first structure layer is larger than that of the second structure layer, the optical structure layer can screen light rays incident from fingerprint ridges and fingerprint valleys, the light rays with incidence angles larger than or equal to a preset angle are blocked from entering the second structure layer, the light rays incident from the fingerprint ridges and the fingerprint valleys are distinguished, the quantity of the light rays of a photosensitive element for receiving a fingerprint Gu Rushe is larger than that of the fingerprint ridges, and accordingly fingerprint images with alternate brightness and darkness are obtained for fingerprint identification. Under strong light environment, the optical structure layer can effectively utilize the light with increased quantity, so that the light and shade difference between the fingerprint valley and the fingerprint ridge formed on the photosensitive element is increased, the fingerprint images with alternate light and shade are clearer, the fingerprint images with high quality are obtained, and the accuracy and the effectiveness of fingerprint identification under strong light environment are ensured.
Description
Technical Field
The application relates to the technical field of display, in particular to an optical fingerprint identification component and electronic equipment.
Background
A fingerprint is made up of a series of ridges and valleys on the surface of the finger tip skin, which is unique to each individual. With the development of fingerprint identification technology, the fingerprint identification technology is widely applied in various fields, such as mobile phones, tablet computers, intelligent wearable devices and the like in electronic equipment terminals; access control and safes in security systems, and the like. Before a user operates the display device with the fingerprint identification function, the user can carry out authority verification by only touching a specific area of the display device with a finger and identifying the fingerprint identification unit, so that the safety of verification is improved while the authority verification is simplified.
Fingerprint recognition can be classified into light sensing fingerprint recognition, capacitance type fingerprint recognition and ultrasonic fingerprint recognition according to its working principle. For light-sensitive fingerprint identification, the intensity of light reflected by the fingerprint ridges and the fingerprint valleys received by the fingerprint identification unit is different, so that the magnitudes of current/voltage signals converted by the reflected light formed at the positions of the fingerprint ridges and the reflected light formed at the fingerprint valleys are different, and fingerprint images with alternate brightness are formed according to the difference of the Gu Ji reflectivity, so that fingerprint identification is realized.
But under strong light environment, reflected light imaging by utilizing the fingerprint valley and ridge can be interfered by a large amount of strong light rays around the finger, so that the acquired fingerprint image is overexposed, and the accuracy of fingerprint identification is affected.
Disclosure of Invention
The application aims to solve the problems that in an optical fingerprint identification component and electronic equipment in the prior art, reflected light imaging by utilizing fingerprint ridges can be interfered by strong light around a finger, so that the acquired fingerprint image is overexposed, and the accuracy of fingerprint identification is affected.
In order to solve the technical problems, the application provides an optical fingerprint identification component, which comprises a substrate, a light sensor layer and an optical structure layer, wherein the light sensor layer is arranged on the surface of the substrate, and the light sensor layer comprises a plurality of photosensitive pixels arranged in an array; the optical structure layer is arranged on one side of the light sensor layer, which is away from the substrate; the optical structure layer comprises a first structure layer and a second structure layer which are attached to each other, and the refractive index of the first structure layer is larger than that of the second structure layer; the optical structure layer is used for blocking light rays with an incident angle larger than a preset angle from refracting into the second structure layer, so that the light rays reflected in the first structure layer or the light rays refracted in the second structure layer are received by the photosensitive pixels to form a fingerprint image; the incident angle is an included angle between the propagation direction of the light and the direction perpendicular to the interface between the first structural layer and the second structural layer, and the preset angle is a critical angle at which the light enters the second structural layer from the first structural layer for total reflection.
The application also provides electronic equipment, a shell and a main board arranged in the shell, the electronic equipment further comprises a display component and the optical fingerprint identification component, the display component is arranged on the shell, the optical fingerprint identification component is arranged on the backlight side of the display component, and the optical fingerprint identification component is electrically connected with the main board.
According to the technical scheme, the beneficial effects of the application are as follows:
in the optical fingerprint identification component and the electronic equipment, based on the fact that light rays entering the optical sensor layer from the fingerprint ridges are mainly large-angle light rays, and light rays entering the optical sensor layer from the fingerprint valleys are mainly small-angle light rays, the first structural layer and the second structural layer with different refractive indexes are arranged, so that the optical structural layer screens the light rays entering the fingerprint ridges and the fingerprint valleys, the light rays with the incident angles larger than or equal to the preset angle are blocked from entering the second structural layer, the quantity of the light rays of the fingerprint Gu Rushe received by the photosensitive element is larger than that of the light rays entering the fingerprint ridges, the fingerprint valley image formed by the photosensitive element is brighter, the image of the formed fingerprint ridges is darker, and the fingerprint image with alternate brightness is obtained, so that fingerprint identification is performed. Under strong light environment, the optical structure layer can effectively utilize the light with increased quantity, so that the light and shade difference between the fingerprint valley and the fingerprint ridge formed on the photosensitive element is increased, the fingerprint images with alternate light and shade are clearer, the fingerprint images with high quality are obtained, and the accuracy and the effectiveness of fingerprint identification under strong light environment are ensured.
Drawings
FIG. 1 is a schematic diagram of an electronic device according to an embodiment of the present application;
FIG. 2 is a schematic diagram of an optical fingerprint recognition module according to an embodiment of the present application;
FIG. 3 is a schematic view of the optical structure layer in the optical fingerprint recognition module shown in FIG. 2;
fig. 4 is another schematic structural view of an optical structural layer in the optical fingerprint recognition device shown in fig. 2.
The reference numerals are explained as follows: 100. an electronic device; 10. an optical fingerprint identification component; 11. a substrate; 112. a circuit layer; 12. a photosensor layer; 121. a photosensitive pixel; 13. an optical structural layer; 131. a first structural layer; 132. a second structural layer; 133. a light absorbing layer; 14. a cover sheet layer; 15. an outer frame; 20. a housing; 30. a main board; 40. a display assembly; 41. a light emitting element; 42. a display cover plate; 43. a polarizer; 200. a fingerprint ridge; 300. fingerprint valleys.
Detailed Description
Exemplary embodiments that embody features and advantages of the present application will be described in detail in the following description. It will be understood that the application is capable of various modifications in various embodiments, all without departing from the scope of the application, and that the description and illustrations herein are intended to be by way of illustration only and not to be construed as limiting the application.
As is well known, biometric identification systems have been increasingly used in life today, wherein fingerprint identification is one of the common identification means. The implementation modes of fingerprint acquisition mainly include an optical type, a capacitive type and an ultrasonic imaging type, wherein the identification range of the optical fingerprint identification technology is relatively large, the cost is relatively low, and the application is relatively wide.
At present, the optical fingerprint technology mainly images through the reflectivity difference between fingerprint ridges and fingerprint valleys. When fingerprint verification is performed, the fingerprint ridges and the fingerprint valleys reflect light emitted by the light source to the image sensor. Because of the difference of the reflectivities of the fingerprint ridges and the fingerprint valleys, the image sensor senses the difference of the light intensities reflected by the fingerprint ridges and the fingerprint valleys so as to form corresponding fingerprint images for fingerprint identification.
However, the inventor of the present application has found through research that when the reflectivity difference between the fingerprint ridges and the fingerprint valleys is directly used for imaging, under a strong light environment, the light reflected by the fingerprint ridges and the fingerprint valleys is interfered by surrounding strong light, so that the overexposure condition of the collected fingerprint image occurs, and the accuracy of fingerprint identification is affected.
In this regard, the present inventors have further studied and analyzed that when a finger touches a screen, a fingerprint ridge is attached to the screen, and an air layer is provided between a fingerprint valley and the screen. Because the density of the finger skin is similar to that of the screen glass, the refraction angle of the light rays at the fingerprint ridge is smaller, and the angle of the light rays transmitted from the fingerprint ridge and entering the screen is only narrowed by a small extent, namely, the light rays entering the screen by the fingerprint ridge are mainly large-angle light rays.
For the transmitted light at the fingerprint valley, because the air layer is arranged between the fingerprint valley and the screen, the density of the air is smaller than that of the screen glass, the refraction angle of the light at the fingerprint valley is larger, and the angle of the light transmitted out of the fingerprint valley and entering the screen is greatly narrowed, so that compared with the light entering the screen from the fingerprint ridge, the light transmitted into the screen from the fingerprint valley is mainly light with a small angle.
Based on the research analysis, the inventor provides an optical fingerprint identification component and electronic equipment, and aims to solve the problem that the fingerprint identification accuracy is affected due to the fact that the imaging of reflected light of fingerprint ridges is interfered by strong light around fingers, so that the acquired fingerprint image is overexposed.
For the purpose of further illustrating the principles and structure of the present application, preferred embodiments of the application will now be described in detail with reference to the accompanying drawings.
Referring to fig. 1 and 2, in an embodiment of the present application, an electronic device 100 includes a housing 20 and a main board 30 disposed inside the housing 20. The electronic device 100 further comprises a display assembly 40 and an optical fingerprint recognition assembly 10, wherein the display assembly 40 is arranged on the housing 20, the optical fingerprint recognition assembly 10 is arranged on the backlight side of the display assembly 40, and the optical fingerprint recognition assembly 10 is electrically connected with the main board 30.
Specifically, the electronic device 100 may be a mobile phone, a television, a tablet computer, a notebook computer, a digital camera, a navigator, an intelligent wearable device, and the like. The electronic device 100 improves the accuracy and success rate of fingerprint identification by obtaining high-quality fingerprint images, and is beneficial to improving the performance and user experience of the electronic device 100.
In this embodiment, the optical fingerprint recognition module 10 includes a substrate 11, a light sensor layer 12, and an optical structure layer 13.
Specifically, a photosensor layer 12 is provided on the surface of the substrate 11, the photosensor layer 12 including photosensitive pixels 121. The optical structure layer 13 is disposed on a side of the light sensor layer 12 facing away from the substrate 11, and the optical structure layer 13 includes a first structure layer 131 and a second structure layer 132 that are attached to each other, where the refractive index of the first structure layer 131 is greater than the refractive index of the second structure layer 132.
The light is reflected by the target fingerprint and enters the optical structure layer 13, and the optical structure layer 13 is used for blocking the light with an incident angle larger than a preset angle from refracting into the second structure layer 132, so that the light reflected by the first structure layer 131 or the light refracted by the second structure layer 132 is received by the photosensitive pixels 121, thereby forming a fingerprint image.
The incident angle is the included angle between the propagation direction of the light ray and the direction perpendicular to the interface between the first structural layer 131 and the second structural layer 132, and the preset angle is the critical angle for the light ray entering the second structural layer 132 from the first structural layer 131 to generate total reflection.
Further, the display assembly 40 of the present embodiment is an OLED screen (Organic Light Emitting Display, organic light emitting diode display screen), and the display assembly 40 includes a display cover 42, a polarizer 43, and a light emitting element 41 sequentially stacked from top to bottom. It will be appreciated that the display assembly 40 may also be an LED screen (Light Emitting Diode, light emitting diode display), LCD screen (Liquid Crystal Display ), or the like.
In this embodiment, the display cover 42 of the display assembly 40 is made of transparent glass, and the polarizer 43 covers the lower surface of the display cover 42. The light emitting element 41 of the present embodiment is an OLED light emitting panel, which can be used as a light source for fingerprint recognition.
When a finger contacts with the surface of the display cover 42, the light emitted by the light emitting element 41 enters the optical structure layer 13 through the reflection of the fingerprint ridges 200 and the fingerprint valleys 300, and is screened by the optical structure layer 13 and finally imaged by the photosensitive pixels 121 in an induction manner, so that fingerprint identification is realized.
With the electronic apparatus 100 of the present embodiment, a light-emitting annulus may be provided in the display module 40, the light-emitting annulus being arranged on the peripheral side of the optical structure layer 13. The light-emitting ring belt can be an LED lamp ring belt, which can be matched with the light-emitting element 41 to be used as a light source for fingerprint identification, so as to enhance the light-emitting brightness of light rays during fingerprint identification and ensure that the photosensitive pixels 121 accurately acquire fingerprint images.
Further, the optical structure layer 13 is disposed on the backlight side of the display assembly 40, and fingerprint recognition is achieved through cooperation between the optical structure layer 13 and the photosensitive pixels 121 under the display assembly 40. This arrangement allows the optical structure layer 13 and the photosensitive pixels 121 to not occupy the display area of the display assembly 40, facilitating the overall screen arrangement of the electronic device 100.
In this embodiment, the optical fingerprint recognition assembly 10 further includes a cover sheet layer 14, and the cover sheet layer 14 is attached under the display assembly 40 by optical adhesive. The cover sheet layer 14 of the present embodiment is made of a transparent material having the same refractive index as the display cover 42 so that light rays emitted from the light sensor layer 12 are emitted at the same angle after passing through the cover sheet layer 14.
Referring to fig. 2 and 3 together, a plurality of optical structure layers 13 may be disposed in the present embodiment, the plurality of optical structure layers 13 are disposed in a matrix between the display assembly 40 and the substrate 11, and a space is provided between two adjacent optical structure layers 13.
In each optical structure layer 13, the first structure layer 131 and the second structure layer 132 are arranged in a direction perpendicular to the surface of the light sensor layer 12, i.e. the interface between the first structure layer 131 and the second structure layer 132 is perpendicular to the surface of the light sensor layer 12. The upper surfaces of the first and second structural layers 131 and 132 are flush and parallel to the surface of the light sensor layer 12.
The first structural layer 131 and the second structural layer 132 of the present embodiment are each made of resin. In addition, the first and second structural layers 131 and 132 may be made of other transparent materials. In the present embodiment, the refractive index of the first structural layer 131 is greater than the refractive index of the second structural layer 132.
After the light reflected by the finger passes through the display component 40 and enters the optical structural layer 13, part of the light is emitted into the first structural layer 131 by the display component 40, and then the light path changes in the first structural layer 131 and the second structural layer 132; still another portion of the light is directed from the light sensor layer 12 into the second structural layer 132 and changes in the optical path at the second structural layer 132.
When light enters the first structural layer 131 from the display assembly 40 and is injected into the second structural layer 132 from the first structural layer 131, the incident angle of the light is an angle between the propagation direction of the light and the direction perpendicular to the interface between the first structural layer 131 and the second structural layer 132.
In the present embodiment, the refractive index of the first structural layer 131 is n1, the refractive index of the second structural layer 132 is n2, and n1 is greater than n2. The critical angle c=arcsin (n 1/n 2) at which light rays enter the second structural layer 132 from the first structural layer 131 and undergo total reflection, and when the incident angle is greater than the critical angle C, the light rays undergo total reflection at the interface of the first structural layer 131 and the second structural layer 132.
For the light ray a reflected by the fingerprint ridge 200 into the optical structure layer 13, the angle between the light ray a and the direction perpendicular to the interface between the first structure layer 131 and the second structure layer 132 is the incident angle α of the light ray a. From the above analysis, the angle of the light reflected by the fingerprint ridge 200 and entering the display device 40 is narrowed, and the light entering the display device 40 from the fingerprint ridge 200 is mainly light with a large angle, i.e. the divergence angle of the light at the interface of the display device 40 is larger.
When the light divergence angle of the fingerprint ridge 200 entering the display assembly 40 is larger, the light is still kept at a larger divergence angle by refraction of the display assembly 40 when entering the optical structural layer 13, so that the included angle between the light a and the direction perpendicular to the interface between the first structural layer 131 and the second structural layer 132, that is, the incident angle α of the light a is mainly a small range of angles.
For ray b reflected by the fingerprint valley 300 into the optical structure layer 13, the angle of ray b with respect to the direction perpendicular to the interface of the first structure layer 131 and the second structure layer 132 is the angle of incidence β of ray b. From the above analysis, the angle of the light reflected by the fingerprint valley 300 and entering the display device 40 is greatly narrowed, and the light entering the display device 40 from the fingerprint ridge 200 is mainly light with a small angle, i.e. the divergence angle of the light at the interface of the display device 40 is smaller.
When the divergence angle of the light beam entering the display assembly 40 from the fingerprint valley 300 is smaller, the light beam still maintains a smaller divergence angle when entering the optical structure layer 13 through the refraction of the display assembly 40, so that the included angle between the light beam b and the direction perpendicular to the interface between the first structure layer 131 and the second structure layer 132, that is, the incident angle β of the light beam b is mainly a wide range of angles.
In summary, the incident angle α of the light ray a is mainly a small range of angles, and the incident angle β of the light ray b is mainly a large range of angles, for the light ray a incident from the fingerprint ridge 200 and the light ray b incident from the fingerprint valley 300. Compared to the critical angle C, the incident angle β of the light ray b incident from the fingerprint valley 300 is larger than the majority of the critical angle C, while the incident angle α of only a few of the light rays a incident from the fingerprint ridge 200 is larger than the critical angle C.
When the incident angle is greater than the critical angle, the incident light ray is totally reflected at the interface of the first and second structural layers 131 and 132. Since the incidence angle β of the majority of the light rays b incident from the fingerprint valley 300 is greater than the critical angle C, the majority of the light rays b incident from the fingerprint valley 300 are totally reflected at the interface of the first structural layer 131 and the second structural layer 132, i.e., the optical structural layer 13 blocks the majority of the light rays b incident at an angle β greater than the critical angle C from entering the second structural layer 132, so that the majority of the light rays b are reflected in the first structural layer 131 and enter the photosensitive pixels 121, and the photosensitive pixels 121 sense a large amount of the light rays b incident from the fingerprint valley 300, thereby forming a brighter image of the fingerprint valley 300.
Since only a few incident angles α of the light rays a incident from the fingerprint ridge 200 are larger than the critical angle C, only a few light rays a incident from the fingerprint ridge 200 are totally reflected at the interface between the first structural layer 131 and the second structural layer 132, and most light rays a enter the second structural layer 132 to be refracted. A small amount of light a totally reflected by the first structural layer 131 enters the photosensitive pixel 121 after being reflected, and a large amount of light a refracted by the second structural layer 132 is absorbed and cannot be received by the photosensitive pixel 121, so that the photosensitive pixel 121 can only receive a small amount of light a incident by the fingerprint ridge 200, thereby forming a darker fingerprint ridge 200 image.
In the optical fingerprint identification assembly 10 of the present embodiment, the optical structure layer 13 can screen the light incident by the fingerprint ridges 200 and the fingerprint valleys 300, so that the photosensitive pixels 121 receive the light incident by the fingerprint valleys 300 more than the fingerprint ridges 200, so that the fingerprint valleys 300 formed by the photosensitive pixels 121 are brighter, and the formed fingerprint ridges 200 are darker, thereby obtaining the fingerprint images with alternate brightness, so as to perform fingerprint identification.
In a strong light environment, the total number of light rays entering the optical structural layer 13 from the finger is increased, so that the number of light rays entering the first structural layer 131 from the fingerprint valley 300 is increased, and the light rays entering the second structural layer 132 from the fingerprint ridge 200 are refracted and absorbed, so that the light and shade difference between the fingerprint valley 300 and the fingerprint ridge 200 formed on the photosensitive pixel 121 is larger, the fingerprint images with alternate light and shade are clearer, and the accuracy of fingerprint identification in the strong light environment is ensured.
As can be seen, for the optical fingerprint identification assembly 10 of the present embodiment, the strong light irradiation does not affect the formation of the fingerprint image, but rather makes the difference of the amounts of light incident by the fingerprint ridges 200 and the fingerprint valleys 300 received by the photosensitive pixels 121 larger, and the difference of the brightness of the images formed by the fingerprint valleys 300 and the fingerprint ridges 200 on the photosensitive pixels 121 is also more obvious, so that the accuracy of fingerprint identification is improved.
Further, in the present embodiment, each optical structure layer 13 further includes a light absorbing layer 133. The light absorbing layer 133 is disposed vertically and is disposed outside the first and second structural layers 131 and 132.
The refractive index of the light absorbing layer 133 of this embodiment is the same as that of the second structural layer 132, and the light absorbing layer 133 includes black light absorbing particles. When light is totally reflected from the interface between the first structural layer 131 and the second structural layer 132 to the interface between the first structural layer 131 and the light-absorbing layer 133, the light is totally reflected due to the constant incident angle, and enters the photosensitive pixel 121 through multiple total reflections. When light is refracted at the interface between the first structural layer 131 and the second structural layer 132 and enters the second structural layer 132, the light refracted at the second structural layer 132 is absorbed by the light absorbing particles in the light absorbing layer 133, so that the light refracted into the second structural layer 132 cannot be received by the photosensitive pixels 121.
The light absorbing layer 133 can ensure that a large amount of light incident from the fingerprint valley 300 enters the photosensitive pixel 121 through total reflection, and ensure that a large amount of light incident from the fingerprint ridge 200 is refracted and absorbed through the second structural layer 132, so that the photosensitive pixel 121 receives the difference of the incident light amounts of the fingerprint ridge 200 and the fingerprint valley 300, and the fingerprint image with alternate brightness is formed more clearly.
Further, in the present embodiment, the substrate 11 further includes a circuit layer 112, and the circuit layer 112 includes a circuit substrate, a flexible circuit flat cable, and a steel reinforcement. The steel reinforcement is used for rapidly absorbing heat of the circuit substrate and radiating the heat into the air, so that the substrate 11 has a better heat radiation effect, and normal operation of the substrate 11 is ensured.
The photosensor layer 12 of the present embodiment includes a plurality of photosensitive pixels 121, and the plurality of photosensitive pixels 121 are arranged on the circuit layer 112 at intervals. In the present embodiment, each photosensitive pixel 121 is disposed corresponding to the optical structure layer 13, that is, a plurality of optical structure layers 13 are arranged in a matrix on the circuit layer 112 corresponding to the optical structure layers 13. This arrangement ensures that light screened by the optical structure layer 13 is accurately received by the photosensitive pixels 121, so that the photosensitive pixels 121 clearly display the fingerprint image.
In addition, in the present embodiment, the optical fingerprint recognition assembly 10 further includes an outer frame 15. The outer frame 15 is disposed between the cover sheet layer 14 and the circuit layer 112, and is disposed outside the optical structure layer 13 and the photosensitive pixels 121.
Referring to fig. 4, in the optical structural layer 13 of the above embodiment, the first structural layer 131 and the second structural layer 132 may also be disposed parallel to the surface of the substrate 11, that is, the interface between the first structural layer 131 and the second structural layer 132 is parallel to the surface of the substrate 11. Wherein the first structural layer 131 is arranged on the side of the second structural layer 132 facing away from the light sensor layer 12.
When the light reflected by the finger enters the optical structural layer 13 through the display component 40 and then is emitted to the interface between the first structural layer 131 and the second structural layer 132 through the first structural layer 131, the incident angle of the light is the included angle between the propagation direction of the light and the direction perpendicular to the interface between the first structural layer 131 and the second structural layer 132.
The refractive index of the first structural layer 131 is n1, the refractive index of the second structural layer 132 is n2, and n1 is greater than n2. The critical angle c=arcsin (n 1/n 2) at which light rays enter the second structural layer 132 from the first structural layer 131 and undergo total reflection, and when the incident angle is greater than the critical angle C, the light rays undergo total reflection at the interface of the first structural layer 131 and the second structural layer 132.
For the light ray a1 reflected by the fingerprint ridge 200 into the optical structure layer 13, the angle between the light ray a1 and the direction perpendicular to the interface between the first structure layer 131 and the second structure layer 132 is the incident angle α1 of the light ray a 1. From the above analysis, the angle of the light reflected by the fingerprint ridge 200 and entering the display device 40 is narrowed, and the light entering the display device 40 from the fingerprint ridge 200 is mainly light with a large angle, i.e. the divergence angle of the light at the interface of the display device 40 is larger.
When the light beam divergence angle of the fingerprint ridge 200 entering the display assembly 40 is larger, the light beam is still kept at a larger divergence angle by refraction of the display assembly 40 when entering the optical structure layer 13, so that the included angle between the light beam a1 and the direction perpendicular to the interface between the first structure layer 131 and the second structure layer 132, that is, the incident angle α1 of the light beam a1 is mainly a wide range of angles.
For ray b1 reflected by fingerprint valley 300 into optical structure layer 13, ray b1 makes an angle of incidence β1 of ray b1 with respect to a direction perpendicular to the interface of first structure layer 131 and second structure layer 132. The angle of light reflected by the fingerprint valleys 300 into the display assembly 40 is greatly narrowed such that light entering the display assembly 40 from the fingerprint ridges 200 is dominated by light rays at small angles, i.e., light rays diverge at the interface of the display assembly 40 at small angles.
When the divergence angle of the light beam entering the display assembly 40 from the fingerprint valley 300 is smaller, the light beam still maintains a smaller divergence angle when entering the optical structure layer 13 through the refraction of the display assembly 40, so that the included angle between the light beam b1 and the direction perpendicular to the interface between the first structure layer 131 and the second structure layer 132, that is, the incident angle β1 of the light beam b1 is mainly a small range of angles.
To sum up, the incident angle α1 of the light ray a1 incident from the fingerprint ridge 200 and the incident angle β1 of the light ray b1 incident from the fingerprint valley 300 are mainly in a wide range of angles, and the incident angle β1 of the light ray b1 is mainly in a small range of angles. Compared to critical angle C, the incident angle α1 of the light ray a1 incident from the fingerprint ridge 200 is larger than the majority of critical angle C, while the incident angle β1 of only a few of the light rays b1 incident from the fingerprint valley 300 is larger than critical angle C.
When the incident angle is greater than the critical angle, the incident light ray is totally reflected at the interface of the first and second structural layers 131 and 132. Since the incident angle α1 of the light ray a1 incident on the fingerprint ridge 200 is larger than the critical angle C, the majority of the light ray a1 incident on the fingerprint ridge 200 is totally reflected at the interface between the first structure layer 131 and the second structure layer 132, i.e. the optical structure layer 13 blocks the majority of the light ray a1 incident on the fingerprint ridge 200 from entering the second structure layer 132, and only a small amount of the light ray a1 incident on the fingerprint ridge 200 is refracted in the second structure layer 132 and received by the photosensitive pixel 121, thereby forming a darker image of the fingerprint ridge 200
Since the incident angle β1 of the light beam b1 incident from the fingerprint valley 300 is smaller than the critical angle C, only a small number of the light beam b1 incident from the fingerprint valley 300 is totally reflected at the interface between the first structural layer 131 and the second structural layer 132, and most of the light beam b1 enters the second structural layer 132 to be refracted, i.e. the optical structural layer 13 blocks a small amount of the light beam b1 incident from the fingerprint valley 300 with the incident angle β1 being larger than the critical angle C from entering the second structural layer 132, so that a large amount of the light beam b1 incident from the fingerprint valley 300 is refracted in the second structural layer 132 to be received by the photosensitive pixel 121, thereby forming a brighter image of the fingerprint valley 300.
In the optical fingerprint identification assembly 10 of the present embodiment, the optical structure layer 13 can screen the light incident by the fingerprint ridges 200 and the fingerprint valleys 300, so that the photosensitive pixels 121 receive the light incident by the fingerprint valleys 300 more than the fingerprint ridges 200, so that the fingerprint valleys 300 formed by the photosensitive pixels 121 are brighter, and the formed fingerprint ridges 200 are darker, thereby obtaining the fingerprint images with alternate brightness, so as to perform fingerprint identification.
For the optical fingerprint identification component and the electronic device of the embodiment, based on the fact that light rays entering the optical sensor layer from the fingerprint ridges are mainly large-angle light rays, light rays entering the optical sensor layer from the fingerprint valleys are mainly small-angle light rays, the first structural layer and the second structural layer with different refractive indexes are arranged, the optical structural layer screens the light rays entering the fingerprint ridges and the fingerprint valleys, the light rays entering the second structural layer from the incident angles larger than or equal to the preset angle are blocked, the quantity of the light rays of the fingerprint Gu Rushe received by the photosensitive element is larger than that of the light rays entering the fingerprint ridges, the fingerprint valley image formed by the photosensitive element is brighter, the image of the formed fingerprint ridges is darker, and accordingly the fingerprint image with alternate brightness and darkness is obtained, so that fingerprint identification is performed. Under strong light environment, the optical structure layer can effectively utilize the light with increased quantity, so that the light and shade difference between the fingerprint valley and the fingerprint ridge formed on the photosensitive element is increased, the fingerprint images with alternate light and shade are clearer, the fingerprint images with high quality are obtained, and the accuracy and the effectiveness of fingerprint identification are ensured.
While the application has been described with reference to several exemplary embodiments, it is to be understood that the terminology used is intended to be in the nature of words of description and of limitation. As the present application may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.
Claims (8)
1. An optical fingerprint recognition assembly, comprising:
a substrate;
a light sensor layer disposed on a surface of the substrate, the light sensor layer including a plurality of photosensitive pixels disposed in an array; and
an optical structure layer arranged on one side of the light sensor layer away from the substrate; the optical structure layer comprises a first structure layer and a second structure layer which are attached to each other, and the refractive index of the first structure layer is larger than that of the second structure layer;
the optical structure layer is used for blocking light rays with an incident angle larger than a preset angle from refracting into the second structure layer, so that the light rays reflected in the first structure layer or the light rays refracted in the second structure layer are received by the photosensitive pixels to form a fingerprint image;
the incident angle is an included angle between the propagation direction of the light and the direction perpendicular to the interface between the first structural layer and the second structural layer, and the preset angle is a critical angle at which the light enters the second structural layer from the first structural layer for total reflection;
the optical structure layers are arranged in a matrix, and a space is arranged between two adjacent optical structure layers;
the first structure layer and the second structure layer are vertically arranged, and the interface of the first structure layer and the second structure layer is perpendicular to the surface of the light sensor layer;
and the light rays with the incidence angle larger than the preset angle are subjected to total reflection at the interface of the first structural layer and the second structural layer, so that the light rays reflected in the first structural layer enter the photosensitive pixels.
2. The optical fingerprint recognition assembly of claim 1, wherein the optical structural layer further comprises a light absorbing layer disposed outside of the first and second structural layers.
3. The optical fingerprint recognition assembly of claim 2, wherein the light absorbing layer has a refractive index that is the same as a refractive index of the second structural layer, the light absorbing layer comprising light absorbing particles.
4. The optical fingerprint recognition assembly of claim 1, wherein each of the optical structure layers is disposed corresponding to one of the photosensitive pixels.
5. The optical fingerprint recognition assembly of claim 2, wherein an interface of the light absorbing layer and the first structural layer is perpendicular to a surface of the light sensor layer, and an interface of the light absorbing layer and the second structural layer is perpendicular to the surface of the light sensor layer.
6. An electronic device comprising a housing and a motherboard disposed inside the housing, wherein the electronic device further comprises a display assembly and an optical fingerprint recognition assembly according to any one of claims 1-5, the display assembly is disposed on the housing, the optical fingerprint recognition assembly is disposed on a backlight side of the display assembly, and the optical fingerprint recognition assembly is electrically connected with the motherboard.
7. The electronic device of claim 6, wherein the display assembly comprises a display cover plate and a polarizer, the display cover plate and the polarizer being stacked.
8. The electronic device of claim 7, wherein the optical fingerprint recognition assembly further comprises a cover plate layer disposed on a side of the optical structure layer facing away from the light sensor layer, the cover plate layer having a refractive index that is the same as a refractive index of the display cover plate.
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| CN110376782B (en) * | 2019-07-31 | 2022-05-10 | 厦门天马微电子有限公司 | Display panel and display device |
| CN111046775A (en) * | 2019-12-06 | 2020-04-21 | Oppo广东移动通信有限公司 | Light collimation component, fingerprint identification device and electronic equipment |
| WO2021138781A1 (en) * | 2020-01-06 | 2021-07-15 | 深圳市汇顶科技股份有限公司 | Fingerprint detection device and electronic device |
| EP4147164A4 (en) * | 2020-05-07 | 2023-10-04 | Fingerprint Cards Anacatum IP AB | Biometric imaging device comprising collimating structures and method of imaging in the biometric imaging device |
| CN113641023A (en) * | 2021-08-06 | 2021-11-12 | 武汉华星光电技术有限公司 | Display panel and electronic device |
| CN113589421A (en) * | 2021-09-16 | 2021-11-02 | 维沃移动通信有限公司 | Light guide member and electronic apparatus |
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