WO2021022680A1 - Fingerprint detection apparatus and electronic device - Google Patents

Abstract

The present application provides a fingerprint detection apparatus, capable of detecting whether the fingerprint of a finger is a 3D fingerprint or a forged 2D fingerprint, thereby improving the security of fingerprint detection. The apparatus comprises: a light guide layer, used for guiding oblique light signals that are incident to a finger above a display screen and returned by the finger to an image acquisition unit; and the image acquisition unit, used for receiving the light signals to obtain a fingerprint image of the finger, wherein a polarization unit is provided in a light path between the finger and the image acquisition unit, and the light signals received by the image acquisition unit comprise light signals having different included angles between a receiving surface therefor and the polarization direction of the polarization unit, for determining whether the fingerprint image is a 3D fingerprint image.

Description

Fingerprint detection device and electronic equipment

This application claims the priority of the PCT application filed with the Chinese Patent Office on August 6, 2019, with the application number PCT/CN2019/099487 and the name "fingerprint detection device and electronic equipment", the entire content of which is incorporated herein by reference Applying.

Technical field

The embodiments of the present application relate to the field of biometric identification, and more specifically, to a fingerprint detection device and electronic equipment.

Background technique

The optical fingerprint module collects the light signal returned by reflection and transmission on the finger, and realizes the under-screen optical fingerprint detection according to the fingerprint information of the finger carried in the light signal. However, by making fake 2D fingerprints, the fingerprint password can be easily cracked, causing huge losses to information security and property security.

Summary of the invention

The embodiments of the present application provide a fingerprint detection device and electronic equipment, which can detect whether a fingerprint of a finger is a 3D fingerprint or a forged 2D fingerprint, thereby improving the security of fingerprint detection.

In the first aspect, a fingerprint detection device is provided, which is set under the display screen of an electronic device, and includes:

The light guide layer is used to guide the inclined light signal incident on the finger above the display screen and returning via the finger to the image acquisition unit;

The image acquisition unit is configured to receive the optical signal to acquire a fingerprint image of the finger, wherein a polarization unit is provided in the optical path between the finger and the image acquisition unit, and the image acquisition unit receives The optical signal includes an optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles, so as to determine whether the fingerprint image is a 3D fingerprint image.

In a possible implementation manner, the polarization unit includes a polarization direction, and the light guide layer is used to guide the optical signals in multiple directions to the image acquisition unit, wherein The angle between the receiving surface of the optical signal and the polarization direction is different.

In a possible implementation, the multiple directions include a first direction and a second direction, wherein the receiving surface of the optical signal in the first direction is perpendicular to the polarization direction, and the light in the second direction The receiving surface of the signal is parallel to the polarization direction.

In a possible implementation, the image acquisition unit includes a plurality of sensors, the number of the light guide layers is multiple, and the plurality of light guide layers respectively correspond to the multiple directions and are used to The optical signals in the direction are respectively guided to the plurality of sensors.

In a possible implementation, the light guide layer includes: a microlens array, including a plurality of microlenses, for converging the optical signal; at least one light blocking layer is sequentially arranged on the microlens array Below, each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein the connection direction of the openings corresponding to the same microlens in each light blocking layer corresponds to the light guide layer Direction.

In a possible implementation, the light guide layer includes an array of light guide channels, the array of light guide channels includes: a plurality of light guide channels, the light guide channels are arranged obliquely, and the oblique direction of the light guide channel Is the direction corresponding to the light guide layer; or, multiple optical fibers, the optical fibers are arranged vertically, and the optical signal in the direction corresponding to the light guide layer is transmitted in the optical fiber based on total reflection.

In a possible implementation, the light guide layer includes: an optical function film layer for transmitting light signals in a direction corresponding to the light guide layer and blocking the light signals in other directions.

In a possible implementation, the image acquisition unit includes a sensor, the number of the light guide layer is one, and the light guide layer includes a plurality of regions, and the plurality of regions respectively correspond to the plurality of regions. Direction, the part of the light guide layer located in each area is used to guide the light signal in the corresponding direction to the sensor.

In a possible implementation, the part of the light guide layer located in each area includes: a microlens array, including a plurality of microlenses, for converging the optical signal; at least one light blocking layer, Are sequentially arranged under the microlens array, each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein the direction of the connection line of the openings corresponding to the same microlens in each light blocking layer Is the direction corresponding to the area.

In a possible implementation manner, the part of the light guide layer located in each region includes: a plurality of light guide channels, the light guide channels are arranged obliquely, and the inclination direction of the light guide channel is the region Corresponding direction; or, multiple optical fibers, the optical fibers are arranged vertically, and the optical signal in the direction corresponding to the area is transmitted in the optical fiber based on total reflection.

In a possible implementation, the part of the light guide layer located in each area includes: an optical function film layer, which is used to transmit light signals in the corresponding direction of the area and block other directions. The light signal.

In a possible implementation manner, the polarization unit includes a plurality of polarization directions, and the light guide layer is used to guide the optical signal in the target direction to the image acquisition unit, wherein all directions of the direction are The angles between the receiving surface of the optical signal and the multiple polarization directions are different.

In a possible implementation manner, the multiple polarization directions form a centrally symmetric pattern.

In a possible implementation manner, the centrally symmetric pattern is circular or square.

In a possible implementation manner, the image acquisition unit includes a plurality of sensors, the number of the light guide layer is more than one, and the plurality of light guide layers are used to capture the light signal in the target direction. Lead to the plurality of sensors respectively.

In a possible implementation, the image acquisition unit includes a sensor, the number of the light guide layer is one, and the light guide layer is used to guide the light signal in the target direction to the sensor.

In a possible implementation, the light guide layer includes: a microlens array, including a plurality of microlenses, for converging the optical signal; at least one light blocking layer is sequentially arranged on the microlens array Below, each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein the connection direction of the openings corresponding to the same microlens in each light blocking layer is the target direction.

In a possible implementation, the light guide layer includes an array of light guide channels, the array of light guide channels includes: a plurality of light guide channels, the light guide channels are arranged obliquely, and the oblique direction of the light guide channel Or, multiple optical fibers, the optical fibers are arranged vertically, and the optical signals in the target direction are transmitted in the optical fibers based on total reflection.

In a possible implementation, the light guide layer includes a light guide channel array, and the light guide channel array includes: an optical function film layer for transmitting the optical signal in the target direction and blocking The optical signal in other directions.

In a possible implementation manner, the polarization unit is located in the display screen.

In a possible implementation manner, the polarization unit is located above the light guide layer.

In a possible implementation manner, the polarization unit is formed on the upper surface of the light guide layer by coating, or the polarization unit is pasted on the upper surface of the light guide layer by optical glue.

In a possible implementation manner, the device further includes a processor, configured to determine whether the fingerprint image is a 3D fingerprint image according to the sharpness of the fingerprint image in different regions.

In a possible implementation manner, the processor is specifically configured to: in the fingerprint image, the resolution of the region corresponding to the optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles is different. At the same time, it is determined that the fingerprint image is a 3D fingerprint image; when the definitions are the same, it is determined that the fingerprint image is not a 3D fingerprint image.

In a possible implementation manner, the device further includes: a filter layer, which is arranged in the light path between the display screen and the image acquisition unit, and is used to filter light signals of non-target wavelength bands so that the target The optical signal of the waveband is transmitted to the image acquisition unit.

In a possible implementation manner, the light filter layer is disposed above the light guide layer.

In the second aspect, an electronic device is provided, including:

Display screen; and,

The fingerprint detection device in the first aspect or any possible implementation of the first aspect.

Based on the above technical solution, a polarization unit is provided in the optical path between the finger and the image capture unit, and the optical signal received by the image capture unit includes light whose receiving surface and the polarization direction of the polarization unit are at different angles. signal. In this way, for the optical signal reflected by the 3D fingerprint, the energy of the S wave and the P wave included in the optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles are different; while the forged 2D fingerprint The reflection that occurs is diffuse reflection, and the energy of the light signal whose receiving surface and the polarization direction are at different angles is the same. Therefore, there is a difference between the fingerprint image of the 3D fingerprint and the 2D fingerprint formed. Based on the difference, it can be judged whether the finger is 3D fingerprint, thereby improving the security of fingerprint detection.

Description of the drawings

Figures 1A and 1B are schematic diagrams of electronic devices to which this application can be applied.

2A and 2B are schematic cross-sectional views of the electronic device shown in FIGS. 1A and 1B along the direction A-A', respectively.

Fig. 3 is a schematic block diagram of a fingerprint detection device according to an embodiment of the present application.

Figure 4 is a schematic diagram of the receiving surface.

Fig. 5 is a schematic diagram of a microlens and a light blocking layer in an embodiment of the present application.

Fig. 6 is a schematic diagram of a microlens and a light blocking layer in an embodiment of the present application.

Fig. 7 is a schematic diagram of a microlens and a light blocking layer in an embodiment of the present application.

Fig. 8 is a schematic diagram of a light guide channel array according to an embodiment of the present application.

Fig. 9 is a schematic diagram of a light guide channel array according to an embodiment of the present application.

FIG. 10 is a schematic diagram of a light guide channel array according to an embodiment of the present application.

FIG. 11 is a schematic diagram of an optical function film layer of an embodiment of the present application.

FIG. 12 is a schematic diagram of an optical function film layer of an embodiment of the present application.

FIG. 13 is a schematic diagram of a receiving surface when multiple sensors are used in an embodiment of the present application.

Fig. 14 is a schematic diagram of a receiving surface when multiple sensors are used in an embodiment of the present application.

FIG. 15 is a schematic diagram of a receiving surface when a single sensor is used in an embodiment of the present application.

Fig. 16 is a schematic diagram of a polarizer according to an embodiment of the present application.

Fig. 17 is a schematic diagram of a polarizing plate according to an embodiment of the present application.

FIG. 18 is a schematic diagram of fingerprint detection of 3D fingerprints according to an embodiment of the present application.

Fig. 19 is a schematic diagram of S light and P light.

FIG. 20 is a schematic diagram of the fingerprint image obtained based on FIG. 18.

FIG. 21 is a schematic diagram of fingerprint detection of 2D fingerprints according to an embodiment of the present application.

detailed description

The technical solution in this application will be described below in conjunction with the drawings.

It should be understood that the embodiments of this application can be applied to fingerprint systems, including but not limited to optical, ultrasonic or other fingerprint detection systems and medical diagnostic products based on optical, ultrasonic or other fingerprint imaging. The embodiments of this application only take optical fingerprint systems as an example For illustration, the embodiments of the present application should not constitute any limitation, and the embodiments of the present application are also applicable to other systems that use optical, ultrasonic, or other imaging technologies.

As a common application scenario, the optical fingerprint system provided in the embodiments of this application can be applied to smart phones, tablet computers, and other mobile terminals with display screens or other electronic devices; more specifically, in the above electronic devices, the optical fingerprint The module can be set in a partial area or the entire area under the display screen to form an under-display or under-screen optical fingerprint system. Alternatively, the optical fingerprint module can also be partially or fully integrated into the display screen of the electronic device, thereby forming an in-display or in-screen optical fingerprint system.

The under-screen optical fingerprint detection technology uses light returned from the top surface of the device's display assembly to perform fingerprint sensing and other sensing operations. The returned light carries the information of the object in contact with the top surface, such as a finger. By collecting and detecting the light returned by the finger, the optical fingerprint detection of the specific optical sensor module located under the display screen is realized. The design of the optical sensor module can be such that the desired optical imaging can be achieved by appropriately configuring optical elements for collecting and detecting the returned light.

Figures 1A and 2A show schematic diagrams of electronic devices to which the embodiments of the present application can be applied. 1A and 2A are schematic diagrams of the orientation of the electronic device 10, and Figs. 1B and 2B are schematic partial cross-sectional diagrams of the electronic device 10 shown in Figs. 1A and 2A along the direction A-A', respectively.

The electronic device 10 includes a display screen 120 and an optical fingerprint module 130. Wherein, the optical fingerprint module 130 is arranged in a partial area below the display screen 120. The optical fingerprint module 130 includes an optical fingerprint sensor, and the optical fingerprint sensor includes a sensing array 133 having a plurality of optical sensing units 131 (also called pixels, photosensitive pixels, pixel units, etc.). The area where the sensing array 133 is located or its sensing area is the fingerprint detection area 103 of the optical fingerprint module 130. As shown in FIG. 1A, the fingerprint detection area 103 is located in the display area of the display screen 120. In an alternative implementation manner, the optical fingerprint module 130 is arranged in other positions, such as on the side of the display screen 120 or the non-transmissive area at the edge of the electronic device 10, and the optical fingerprint module 130 is designed to The optical signal from at least a part of the display area of the display screen 120 is guided to the optical fingerprint module 130, so that the fingerprint detection area 103 is actually located in the display area of the display screen 120.

It should be understood that the area of the fingerprint detection area 103 may be different from the area of the sensing array 133 of the optical fingerprint module 130, such as an optical path design for imaging through a lens, a reflective folding optical path design, or other optical path designs such as light convergence or reflection. , So that the area of the fingerprint detection area 103 of the optical fingerprint module 130 is larger than the area of the sensing array 133 of the optical fingerprint module 130. In other alternative implementation manners, if the optical path is guided by, for example, light collimation, the fingerprint detection area 103 of the optical fingerprint module 130 can also be designed to be the same as the area of the sensing array 133 of the optical fingerprint module 130. Basically the same.

Therefore, when the user needs to unlock the electronic device 10 or perform other fingerprint verification, he only needs to press his finger on the fingerprint detection area 103 located on the display screen 120 to realize fingerprint input. Since fingerprint detection can be implemented in the screen, the electronic device 10 adopting the above structure does not need to reserve space on the front side for setting fingerprint buttons (such as the Home button), so that a full screen solution can be adopted, that is, the display area of the display screen 120 It can be basically extended to the front of the entire electronic device 10.

As an optional implementation, as shown in FIG. 1B, the optical fingerprint module 130 includes a light detecting part 134 and an optical component 132. The light detection part 134 includes the sensor array 133, a reading circuit electrically connected to the sensor array 133, and other auxiliary circuits, which can be fabricated on a chip (Die) by a semiconductor process to form an optical fingerprint sensor ( Also called optical fingerprint chip, sensor, sensor chip, chip, etc.). The sensing array 133 is specifically a photodetector (Photodetector) array, which includes a plurality of photodetectors distributed in an array, and the photodetectors can be used as the above-mentioned optical sensing unit. The optical component 132 may be disposed above the sensing array 133 of the light detecting part 134, and it may specifically include a filter layer (Filter), a light guide layer or a light path guiding structure, and other optical elements. The filter layer It can be used to filter out the ambient light penetrating the finger, and the light guide layer is mainly used to guide the reflected light reflected from the surface of the finger to the sensor array 133 for fingerprint detection.

In terms of specific implementation, the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component. For example, the optical component 132 and the optical detection part 134 may be packaged in the same optical fingerprint chip, or the optical component 132 may be arranged outside the chip where the optical detection part 134 is located, for example, the optical component 132 is attached above the chip, or some components of the optical assembly 132 are integrated into the chip.

Among them, the light guide layer of the optical component 132 has multiple implementation schemes. For example, the light guide layer may specifically be a collimator (Collimator) layer fabricated on a semiconductor silicon wafer, which has a plurality of collimator units or a microhole array, and the collimator unit may be specifically small holes, from Among the reflected light reflected by the finger, the light incident perpendicularly to the collimating unit can pass through and be received by the optical sensor unit below it, while the light with an excessively large incident angle is reflected inside the collimating unit multiple times. Attenuated, each optical sensor unit can basically only receive the reflected light reflected by the fingerprint lines directly above it, so that the sensor array 133 can detect the fingerprint image of the finger.

In another implementation, the light guide layer may also be an optical lens (Lens) layer, which has one or more lens units, such as a lens group composed of one or more aspheric lenses, which is used to The reflected light reflected from the finger is condensed to the sensing array 133 of the light detection part 134 below it, so that the sensing array 133 can perform imaging based on the reflected light, thereby obtaining a fingerprint image of the finger. Optionally, the optical lens layer may further have a pinhole formed in the optical path of the lens unit, and the pinhole may cooperate with the optical lens layer to expand the field of view of the optical fingerprint module 130 to improve The fingerprint imaging effect of the optical fingerprint module 130 is described.

In other implementations, the light guide layer may also specifically adopt a micro-lens (Micro-Lens) layer. The micro-lens layer has a micro-lens array formed by a plurality of micro-lens, which may be through a semiconductor growth process or other processes. It is formed above the sensing array 133 of the light detecting part 134, and each microlens may correspond to one of the sensing units of the sensing array 133, respectively. Another optical film layer, such as a dielectric layer or a passivation layer, may also be formed between the microlens layer and the sensing unit. Further, a light blocking layer (also called a light blocking layer, a light blocking layer, etc.) with micro holes may be included between the micro lens layer and the sensing unit, wherein the micro holes are formed in the corresponding micro lens. Between the sensor unit and the sensor unit, the light blocking layer can block the optical interference between the adjacent micro lens and the sensor unit, and make the light corresponding to the sensor unit converge into the micro hole through the micro lens, and It is transmitted to the sensing unit via the micro-hole for optical fingerprint imaging.

It should be understood that the above-mentioned several implementation schemes of the light guide layer can be used alone or in combination. For example, a micro lens layer may be further provided above or below the collimator layer or the optical lens layer. Of course, when the collimator layer or the optical lens layer is used in combination with the micro lens layer, its specific laminated structure or optical path may need to be adjusted according to actual needs.

As an optional implementation manner, the display screen 120 may adopt a display screen with a self-luminous display unit, such as an organic light-emitting diode (Organic Light-Emitting Diode, OLED) display or a micro-LED (Micro-LED) display. Screen. Taking an OLED display screen as an example, the optical fingerprint module 130 can use the display unit (ie, an OLED light source) of the OLED display screen 120 in the fingerprint detection area 103 as an excitation light source for optical fingerprint detection. When the finger 140 is pressed on the fingerprint detection area 103, the display screen 120 emits a beam of light 111 to the finger 140 above the fingerprint detection area 103. The light 111 is reflected on the surface of the finger 140 to form reflected light or pass through all the fingers. The finger 140 scatters to form scattered light. In related patent applications, for ease of description, the above-mentioned reflected light and scattered light are also collectively referred to as reflected light. Because the ridge 141 and valley 142 of the fingerprint have different light reflection capabilities, the reflected light 151 from the fingerprint ridge and the reflected light 152 from the fingerprint valley have different light intensities, and the reflected light passes through the optical component 132. Then, it is received by the sensing array 133 in the optical fingerprint module 130 and converted into a corresponding electrical signal, that is, a fingerprint detection signal. Based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification is further performed, thereby realizing an optical fingerprint detection function in the electronic device 10.

In other implementations, the optical fingerprint module 130 may also use a built-in light source or an external light source to provide an optical signal for fingerprint detection. In this case, the optical fingerprint module 130 may be suitable for non-self-luminous display screens, such as liquid crystal display screens or other passively-luminous display screens. Taking a liquid crystal display with a backlight module and a liquid crystal panel as an example, in order to support the under-screen fingerprint detection of the liquid crystal display, the optical fingerprint system of the electronic device 10 may also include an excitation light source for optical fingerprint detection. The excitation light source may specifically be an infrared light source or a light source of non-visible light of a specific wavelength, which may be arranged under the backlight module of the liquid crystal display or in the edge area under the protective cover of the electronic device 10, and the The optical fingerprint module 130 may be arranged under the edge area of the liquid crystal panel or the protective cover and guided by the light path so that the fingerprint detection light can reach the optical fingerprint module 130; or, the optical fingerprint module 130 may also be arranged at all Below the backlight module, and the backlight module is designed to allow the fingerprint detection light to pass through the liquid crystal panel and the backlight module and reach the optical Fingerprint module 130. When the optical fingerprint module 130 uses a built-in light source or an external light source to provide an optical signal for fingerprint detection, the detection principle is the same as that described above.

It should be understood that, in specific implementation, the electronic device 10 may also include a transparent protective cover, and the cover may be a glass cover or a sapphire cover, which is located above the display screen 120 and covers the electronic device. The front of 10. Therefore, in the embodiments of the present application, the so-called finger pressing on the display screen 120 actually refers to pressing on the cover plate above the display screen 120 or covering the surface of the protective layer of the cover plate.

The electronic device 10 may further include a circuit board 150, and the circuit board 150 is disposed under the optical fingerprint module 130. The optical fingerprint module 130 can be adhered to the circuit board 150 through adhesive, and is electrically connected to the circuit board 150 through bonding pads and metal wires. The optical fingerprint module 130 can realize electrical interconnection and signal transmission with other peripheral circuits or other components of the electronic device 10 through the circuit board 150. For example, the optical fingerprint module 130 may receive the control signal of the processing unit of the electronic device 10 through the circuit board 150, and may also output the fingerprint detection signal from the optical fingerprint module 130 to the processing unit of the terminal device 10 through the circuit board 150 or Control unit, etc.

In some implementations, the optical fingerprint module 130 may include only one optical fingerprint sensor. At this time, the fingerprint detection area 103 of the optical fingerprint module 130 has a small area and a fixed position. Therefore, the user needs to input fingerprints. Press the finger to a specific position of the fingerprint detection area 103, otherwise the optical fingerprint module 130 may not be able to collect fingerprint images, resulting in poor user experience. In other alternative embodiments, the optical fingerprint module 130 may include multiple optical fingerprint sensors. The multiple optical fingerprint sensors may be arranged side by side under the display screen 120 in a splicing manner, and the sensing areas of the multiple optical fingerprint sensors collectively constitute the fingerprint detection area 103 of the optical fingerprint module 130. Therefore, the fingerprint detection area 103 of the optical fingerprint module 130 can be extended to the main area of the lower half of the display screen, that is, to the area where the finger is habitually pressed, so as to realize the blind fingerprint input operation. Further, when the number of optical fingerprint sensors is sufficient, the fingerprint detection area 103 can also be extended to half of the display area or even the entire display area, thereby realizing half-screen or full-screen fingerprint detection.

For example, in the electronic device 10 shown in FIGS. 2A and 2B, the optical fingerprint module 130 in the electronic device 10 includes a plurality of optical fingerprint sensors, and the plurality of optical fingerprint sensors may be arranged side by side in the Below the display screen 120 and the sensing areas of the multiple optical fingerprint sensors collectively constitute the fingerprint detection area 103 of the optical fingerprint module 130.

Optionally, corresponding to the multiple optical fingerprint sensors of the optical fingerprint module 130, the optical component 132 may include multiple light guide layers, and each light guide layer corresponds to an optical fingerprint sensor, and is attached to the optical fingerprint sensor. It is arranged above the corresponding optical fingerprint sensor. Alternatively, the plurality of optical fingerprint sensors may also share an integral light guide layer, that is, the light guide layer has an area large enough to cover the sensing array of the plurality of optical fingerprint sensors.

In addition, the optical component 132 may also include other optical elements, such as a filter or other optical films, which may be arranged between the light guide layer and the optical fingerprint sensor, or arranged on the The display screen 120 and the light guide layer are mainly used to isolate the influence of external interference light on the optical fingerprint detection. Wherein, the filter can be used to filter the ambient light that penetrates the finger and enters the optical fingerprint sensor through the display screen 120. Similar to the light guide layer, the optical filter may be separately provided for each optical fingerprint sensor to filter out interference light, or a large-area optical filter may be used to simultaneously cover the multiple optical fingerprint sensors.

The light guide layer may also be replaced by an optical lens (Lens), and a small hole formed by a light-shielding material above the optical lens can cooperate with the optical lens to converge the fingerprint detection light to the optical fingerprint sensor below to realize fingerprint imaging. Similarly, each optical fingerprint sensor may be configured with an optical lens to perform fingerprint imaging, or the multiple optical fingerprint sensors may also use the same optical lens to realize light convergence and fingerprint imaging. In other alternative embodiments, each optical fingerprint sensor may even have two sensing arrays (Dual Array) or multiple sensing arrays (Multi-Array), and two or more optical lenses are configured to cooperate with the two at the same time. Or multiple sensing arrays perform optical imaging, thereby reducing the imaging distance and enhancing the imaging effect.

During fingerprint detection, the light source illuminates the finger above the display screen, and the optical fingerprint sensor collects the light signal returned by the reflection or scattering of the finger, so as to obtain the fingerprint information of the finger. However, if the fingerprint image of the finger is copied and the fingerprint image is used for fingerprint detection, the fingerprint password can be easily cracked, causing huge losses to information security and property security.

Therefore, the embodiment of the present application provides a fingerprint detection solution, which can detect whether the fingerprint of the finger is a 3D fingerprint or a forged 2D fingerprint, thereby improving the security of fingerprint detection.

Fig. 3 is a schematic block diagram of a fingerprint detection device according to an embodiment of the present application. The device 300 is arranged under the display screen of the electronic device to realize the under-screen optical fingerprint detection. Wherein, the device 300 includes:

The light guide layer 310 is used to guide the inclined light signal incident on the finger above the display screen and returning through the finger to the image acquisition unit 320; and,

The image acquisition unit 320 is configured to receive the light signal to acquire a fingerprint image of the finger.

Wherein, a polarizer (POL) unit 330 is provided in the optical path between the finger and the image acquisition unit. The optical signals received by the image acquisition unit 320 include optical signals whose receiving surface and the polarization direction of the polarization unit 330 are at different angles, so as to determine whether the fingerprint image is a 3D fingerprint image.

In this embodiment, a polarization unit is provided in the optical path between the finger and the image acquisition unit, and the optical signals received by the image acquisition unit include optical signals whose receiving surface and the polarization direction of the polarization unit are at different angles. In this way, for the optical signal reflected by the 3D fingerprint, the energy of the S wave and the P wave included in the optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles are different; while the forged 2D fingerprint The reflection that occurs is diffuse reflection, and the energy of the light signal whose receiving surface and the polarization direction are at different angles is the same. Therefore, there is a difference between the fingerprint image of the 3D fingerprint and the 2D fingerprint formed. Based on the difference, it can be judged whether the finger is 3D fingerprint, thereby improving the security of fingerprint detection.

The receiving surface is the plane formed by the incident light and the reflected light, that is, the transmission surface where the optical signal is located, so the receiving surface can also be called the incident surface. The receiving surface is perpendicular to the display screen and the pixels of the image acquisition unit, that is, the photosensitive surface of the photo-diode (PD).

In the embodiment of the present application, the tilt angle of the optical signal returned by the finger may be between 10 degrees and 50 degrees, for example.

For the image acquisition unit 320, reference may be made to the description of the light detection part 134 in FIG. 1B and FIG. 2B, which will not be repeated here.

The embodiment of the present application does not make any limitation on the position of the polarization unit 330. The polarization unit 330 can be arranged at any position in the optical path between the finger and the image acquisition unit 320.

For example, the polarization unit 330 is disposed in the display screen, such as above the OLED light-emitting layer of the display screen.

For another example, the polarization unit 330 is disposed above the light guide layer 310, such as formed on the upper surface of the light guide layer 310 by coating, or pasted on the upper surface of the light guide layer 310 by optical glue. Wherein, the refractive index of the optical glue can be close to the refractive index of the polarizing unit 330 to avoid loss.

For another example, the polarization unit 330 is disposed above the image acquisition unit 320, such as formed on the upper surface of the image acquisition unit 320 by coating, or pasted on the upper surface of the image acquisition unit 320 by optical glue. Wherein, the refractive index of the optical glue can be close to the refractive index of the polarizing unit 330 to avoid loss.

Generally, for an LCD display screen or an OLED display screen, the polarization unit 330 may be disposed inside the display screen to simultaneously implement related functions of the display screen. For a micro LED (Micro LED) display screen, since the polarization unit 330 is usually not needed in the display screen, the polarization unit 330 can be provided in the fingerprint detection device 300, for example, the light guide layer 310 or the image acquisition unit 320. The upper surface is used to judge the authenticity of the fingerprint.

In the embodiment of the present application, the light guide layer may be used to guide light signals in one or more inclined receiving surfaces. One or more polarization directions can be set on the polarization unit 330. Through the cooperation between the polarization unit 330 and the light guide layer 310, the optical signals received by the image acquisition unit 320 can include optical signals with different angles between its receiving surface and the polarization direction of the polarization unit 300, and It is used to determine whether the fingerprint of the finger is a 3D fingerprint or a forged 2D fingerprint.

The embodiment of the present application provides two ways to determine the authenticity of fingerprints, which will be described in detail below with reference to FIGS. 4-17. Hereinafter, the horizontal plane is the plane where the display screen of the electronic device is located. The horizontal direction refers to the direction parallel to the display screen.

Way 1

The polarization unit 330 includes one polarization direction, and the light guide layer 310 is used to guide light signals in multiple directions to the image acquisition unit 320. Wherein, the angles between the receiving surface of the optical signals in the multiple directions and the polarization direction are different.

Wherein, the receiving surface of the optical signal is perpendicular to the display screen, and the polarization direction of the polarization unit 330 is parallel to the display screen, so the polarization direction is perpendicular to the receiving surface. However, the angle between the polarization direction and the receiving surface may be different.

For example, the multiple directions include a first direction and a second direction. Wherein, the receiving surface of the optical signal in the first direction is perpendicular to the polarization direction, and the receiving surface of the optical signal in the second direction is parallel to the polarization direction. It should be understood that optical signals in multiple directions can be transmitted on the same receiving surface. Generally, the light guide layer 310 is used to guide the optical signals in one direction to the image acquisition unit 320.

4, the polarization direction of the polarizer 330 is shown by the dotted arrow, the receiving surface 3101 and the polarization direction of the polarizer 330 are parallel (the angle is 0 degrees), and the receiving surface 3102 is perpendicular to the polarization direction of the polarizer 330 (the angle is 90 degrees). The angle between the receiving surface and the polarization direction can also be other values, such as the receiving surface 3103 shown in FIG. 4.

In this way 1, in order to realize that the angle between the receiving surface of the optical signal and the polarization direction of the polarization unit 330 is different, the light guide layer 310 can be used to separate the different receiving surfaces while keeping the polarization direction of the polarization unit 330 unchanged. The optical signal inside is guided to the image acquisition unit 320, so that the optical signal received by the image acquisition unit 320 includes the optical signal whose receiving surface and the polarization direction are at different angles.

In this way 1, the image acquisition unit 320 may include one sensor, such as shown in FIG. 1A and FIG. 1B; the image acquisition unit 320 may also include multiple sensors, such as shown in FIG. 2A and FIG. 2B.

When the image acquisition unit 320 includes multiple sensors, the number of the light guide layer 310 is multiple. The plurality of light guide layers 310 respectively correspond to the plurality of directions. Wherein, the multiple light guide layers 310 are used to guide light signals in corresponding directions to the multiple sensors respectively.

Wherein, each light guide layer 310 can be implemented in the following ways.

In an implementation manner, each light guide layer 310 includes:

The microlens array 311 includes a plurality of microlenses for converging the optical signal;

At least one light blocking layer 312 is sequentially arranged under the microlens array 311, each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein each light blocking layer corresponds to the same microlens The direction of the connection lines of the openings is the direction corresponding to the light guide layer 310.

Wherein, the projection of the condensing surface of each microlens on a plane perpendicular to its optical axis may be rectangular or circular. The condensing surface of the microlens is a surface used to converge light. The condensing surface may be spherical or aspherical. Preferably, the curvature of the condensing surface in all directions is the same, so that the focal point of the microlens when imaging the light in all directions is at the same position, thereby ensuring the imaging quality.

Each microlens may correspond to one pixel in the image acquisition unit 320. Wherein, the oblique light signal condensed by each microlens passes through the openings in each light blocking layer corresponding to the microlens to reach the corresponding pixels.

Since the openings in the light blocking layer are used to guide the light, in order to make the inclined light signal reach the image acquisition unit 320, the lines of the openings corresponding to the same microlens in each light blocking layer should be inclined. The tilt angle is equal to or approximately equal to the tilt angle of the optical signal.

The light blocking layer 312 may be provided with one layer or multiple layers.

For example, as shown in FIG. 5, when a light blocking layer 312 is used, the light blocking layer 312 can be integrated in the image acquisition unit 320, for example, a metal mask is used to form above the pixel array of the image acquisition unit 320 A light blocking layer.

For example, as shown in FIG. 6 and FIG. 7, when multiple light blocking layers 312 are used, the inclination angle of the connection line of the openings corresponding to the same microlens in each light blocking layer determines the inclination angle of the light signal reaching the sensor. The openings in each light blocking layer corresponding to the same microlens are sequentially shifted from top to bottom, so that the optical signal in the corresponding direction is transmitted to the corresponding pixel. Wherein, the last light blocking layer 312 in FIG. 6 and FIG. 7 can be integrated in the image acquisition unit 320, thereby improving reliability.

The size of the openings in each light blocking layer corresponding to the same microlens can be sequentially reduced from top to bottom, so as to guide the optical signal within a certain angle range to the corresponding pixel, as shown in FIG. 7 for example.

A transparent medium layer may also be provided between the microlens array 311, the light blocking layer 312 and the image acquisition unit 320. Wherein, the transparent medium layer can be used to connect the microlens array 311, the light blocking layer 312, and the image acquisition unit 320, and fill the opening in the at least one light blocking layer. The transparent medium layer can transmit optical signals in the target wavelength band, that is, optical signals in the wavelength band required for fingerprint detection. For example, the transparent medium layer may be oxide or nitride.

The transparent medium layer may include multiple layers to realize functions such as protection, transition and buffering respectively. For example, a transition layer can be provided between the inorganic material layer and the organic material layer to achieve a tight connection; another example, a protective layer can be provided on the easily oxidized layer to achieve protection.

In another implementation manner, each light guide layer 310 includes an array of light guide channels 313, and the light guide channels are used to transmit optical signals in one direction.

For example, the light guide channel array 313 includes a plurality of light guide channels, and the light guide channels are arranged obliquely. Wherein, the inclined direction of the light guide channel is the direction corresponding to the light guide layer 310. The light guide channel may be formed of air through holes or light-transmitting materials.

As shown in FIG. 8, the light guide layer 310 is arranged parallel to the display screen 340, and the light guide channel is an inclined channel, which has a certain inclination with respect to the surface of the light guide layer 310, so that the transmission direction is the same as the inclined direction of the light guide channel. The optical signal can be transmitted to the image acquisition unit 320 through the light guide channel, while the optical signal in other directions is blocked.

Of course, a light guide channel perpendicular to the surface of the light guide layer 310 can also be made on the light guide layer 310 first, and then the light guide layer 310 is inclined to a certain angle with respect to the display screen 340, as shown in FIG. 9 for example. At this time, optical signals with the same transmission direction as the tilt direction of the light guide layer 310 can be transmitted to the image acquisition unit 320 through the light guide channel, while optical signals in other directions are blocked.

For another example, the light guide channel array 313 includes a plurality of optical fibers, and the optical fibers are arranged vertically. The optical signal in the direction corresponding to the light guide layer 310 is transmitted in the optical fiber based on total reflection.

The transmission of optical signals in optical fibers is based on the principle of total reflection. Due to the difference in refractive index between the core and the cladding of the optical fiber, the optical signal meeting the total reflection angle is totally reflected at the interface between the core and the cladding, so that the qualified optical signal is blocked inside the core and propagates forward. As shown in FIG. 10, the optical signal enters at one end of the optical fiber, and after performing at least one total reflection in the optical fiber, it exits from the other end of the optical fiber.

In another implementation manner, each light guide layer 310 includes an optical functional film layer 314 for transmitting light signals in a direction corresponding to the light guide layer 310 and blocking the light signals in other directions.

The optical function film layer 314 may be, for example, a grating film or a prism film.

For example, as shown in FIG. 11, the optical function film layer 314 can select the optical signal in a fixed direction among the optical signals in various directions and allow it to exit from the optical function film layer 314, so that the optical signal reaches the image acquisition unit. 320. The optical signals in other directions are attenuated or reflected, and thus cannot be emitted from the optical function film layer 314.

Further, the optical function film layer 314 can also refract the optical signal, so that the optical signal can be perpendicularly incident on the pixels of the image acquisition unit 320.

For example, as shown in FIG. 12, the optical function film layer 314 can transmit the optical signal in the direction A and refract the optical signal so that the optical signal can be vertically emitted from the optical function film layer 314 and incident To the pixels in the image acquisition unit 320. When the light signal is received vertically by the pixel, its quantum efficiency is the highest, so the optimal photoelectric conversion efficiency can be obtained and the fingerprint detection performance is improved.

The optical function film layer 314 may be integrated in the image acquisition unit 320; or, the optical function film layer 314, as a relatively independent device from the image acquisition unit 320, is arranged above the image acquisition unit 320, for example, is pasted on the image acquisition unit through optical glue. The upper surface of 320.

It should be understood that each light guide layer 310 described above corresponds to a sensor, and can be respectively disposed above the corresponding sensor, but the application is not limited to this. The plurality of sensors may also share an integral light guide layer 310, which has an area large enough to cover the plurality of sensors. At this time, the light guide layer 310 includes a plurality of regions, the plurality of regions respectively correspond to the plurality of directions, and the plurality of sensors are respectively disposed under the plurality of regions. The part of the light guide layer 310 located in each area is used to guide the light signal in the corresponding direction to the corresponding sensor.

When the image acquisition unit 320 includes a sensor, a light guide layer 310 may be provided above the sensor. The light guide layer 310 includes multiple regions, and the multiple regions respectively correspond to the multiple directions. The part of the light guide layer 310 located in each area is used to guide the light signal in the corresponding direction to the sensor.

In an implementation manner, the portion of the light guide layer 310 located in each area includes: a microlens array, including a plurality of microlenses, for converging the optical signal; and, at least one light blocking Layers are sequentially arranged below the microlens array, and each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses. Wherein, the connection direction of the openings corresponding to the same microlens in each light blocking layer is the direction corresponding to the area.

In another implementation manner, the portion of the light guide layer located in each region includes: a plurality of light guide channels, the light guide channels are arranged obliquely, and the inclination direction of the light guide channel is corresponding to the region Or, multiple optical fibers, the optical fibers are arranged vertically, and the optical signal in the direction corresponding to the area is transmitted in the optical fiber based on total reflection.

In another implementation manner, the part of the light guide layer located in each area includes: an optical function film layer for transmitting light signals in a direction corresponding to the area, and blocking the light signals in other directions Light signal.

It should be understood that for the part of the light guide layer 310 located in each area, the structure can refer to the related descriptions of FIGS. 5 to 12, and for the sake of brevity, the details are not repeated here.

When the image acquisition unit 320 includes multiple sensors, multiple light guide layers corresponding to the multiple sensors are respectively used to guide light signals in different directions to the corresponding sensors. For example, in the top view shown in FIG. 13, the dashed arrow indicates the polarization direction of the linear polarization unit 330, and the solid arrow indicates the projection of the receiving surface of the optical signal in the horizontal plane. The image acquisition unit 320 includes two sensors. The sensing areas corresponding to the two sensors are the sensing area 341 and the sensing area 342, respectively, and a light guide layer is provided above the two sensors. One of the light guide layers is used to transmit optical signals in the first direction. It is assumed that the receiving surface of the light signal in the first direction is the receiving surface 1302 in FIG. 4, which is perpendicular to the polarization direction of the polarizer 330; the other light guide layer is used for For transmitting the optical signal in the second direction, it is assumed that the receiving surface of the optical signal in the second direction is the receiving surface 1301 in FIG. 4, which is parallel to the polarization direction of the polarizer 330. In this way, the two sensors can respectively receive the optical signals in the receiving planes perpendicular and parallel to the polarization direction.

It should be understood that the light guide layers corresponding to the two sensors may be identical light guide layers, that is, the two light guide layers are used to guide light signals with the same inclination angle. When assembling the fingerprint module, one light guide layer can be rotated 90 degrees horizontally relative to the other light guide layer, so that the inclination angles of the light signals guided by the two light guide layers can be the same, but the receiving surfaces are perpendicular to each other , For example, the situation shown in FIG. 13 is formed.

For another example, as shown in FIG. 14, when the image acquisition unit 320 includes 4 sensors, 4 identical light guide layers are provided, and when the 4 light guide layers are installed, they can be rotated horizontally by 90 degrees in sequence, so that the The light signal is guided to the corresponding 4 sensors. Among them, the optical signals received by the two diagonal sensors are located on the same receiving surface, but the transmission directions of the optical signals are different.

When the image acquisition unit includes a sensor, a light guide layer is arranged above the sensor. The parts of the light guide layer located in different regions are respectively used to guide light signals in different directions to the sensor. For example, in the top view shown in FIG. 15, the dashed arrow indicates the polarization direction of the linear polarization unit 330, and the solid arrow indicates the projection of the receiving surface of the optical signal on the horizontal plane. The image acquisition unit 320 includes a sensor, and the sensing area corresponding to the sensor is the sensing area 343. A part of the light guide layer is used to guide the light signal in the first direction to the corresponding pixel in the sensor, and the other part of the light guide layer is used to guide the light signal in the second direction to the corresponding pixel in the sensor . The receiving surfaces of the optical signal in the first direction and the second direction are 1301 and 1302, respectively, and the receiving surface 1301 and the receiving surface 1302 are parallel and perpendicular to the polarization direction.

Way 2

The polarization unit 330 includes multiple polarization directions, and the light guide layer 310 is used to guide the optical signal in the same direction (for example, the target direction) to the image acquisition unit 320, wherein the optical signal in the target direction The angle between the receiving surface and the multiple polarization directions is different.

In this way 2, in order to realize the difference in the angle between the oblique receiving surface of the optical signal and the polarization direction of the polarization unit 330, the receiving surface of the optical signal guided by the light guide layer 310 can be kept unchanged. Multiple polarization directions are made on the unit 330, so that the optical signals received by the image acquisition unit 320 include optical signals whose receiving surface and the polarization direction are at different angles.

Preferably, the plurality of polarization directions include two directions perpendicular to each other. Among them, the two polarization directions are respectively perpendicular and parallel to the receiving surface of the optical signal.

For example, the plurality of polarization directions form a centrally symmetric pattern. The centrally symmetric pattern is, for example, a circle or a square.

16 and 17 are the top views of the polarizing plate, the black arrow is the projection of the light signal receiving surface on the horizontal plane. It can be seen that the angles between the receiving surface and the polarization directions of the polarizer are different. Taking FIG. 17 as an example, the multiple polarization directions of the polarization unit 330 form a circle. Among them, the polarization direction on the P1-P2 connection is perpendicular to the oblique receiving surface of the optical signal (the angle is 90 degrees); the polarization direction on the P3-P4 connection is parallel to the oblique receiving surface of the optical signal (the angle is 0 degrees) ); The angle between other polarization directions and the receiving surface is between 0 degrees and 90 degrees. It should be understood that the polarization direction in FIG. 17 is the tangential direction of the circle shown. For example, the polarization direction on the P1-P2 line is perpendicular to the P1-P2 line, and the polarization direction on the P3-P4 line is parallel to P3. -P4 connection.

In order to more clearly illustrate the influence of the angle between the receiving surface of the optical signal and the polarization direction on the fingerprint image. First, the principles of 3D fingerprint detection and 2D fingerprint detection will be explained with reference to FIGS. 18 and 19.

Figure 18 shows the fingerprint detection of 3D fingerprints. There is blood and tissue in the ridge of the fingerprint of the finger 350, and the light incident on the ridge is absorbed by the ridge, and the light emitted from the ridge is less. There is an air gap between the valley of the fingerprint and the display screen 340, so that the light incident to the valley is reflected at the glass-air interface, so more light emerges from the valley. Therefore, the fingerprint image acquired based on the reflected light appears as bright and dark. Since the embodiment of the present application performs fingerprint detection based on oblique light, after the light is reflected by the finger, the light returned from the finger includes S light and P light. Assuming that the polarization unit 330 is a polarization unit with a circular polarization direction shown in FIG. 17, after passing through the light guide layer 310, the receiving surface where the optical signal in the target direction is located is perpendicular to the polarization direction in the P1-P2 direction, and Parallel to the polarization direction on the P3-P4 connection. Since the polarization direction on the P1-P2 connection is perpendicular to the receiving surface, in this direction, the S light in the optical signal can pass, but the P light is blocked; and the polarization direction on the P3-P4 connection is The planes are parallel and straight, so in this direction, the P light in the optical signal can pass, but the S light is blocked. In other polarization directions, the components of transmitted S light and P light gradually change.

Generally, as shown in FIG. 19, when the incident angle is smaller than the Brewster angle, the energy of the S light in the reflected light is greater than the energy of the P light. And, as the incident angle increases, the energy of S light gradually increases, and the energy of P light gradually decreases. Among them, the vibration direction of S light is perpendicular to the receiving surface, and the vibration direction of P light is parallel to the receiving surface.

Fig. 20 is a fingerprint image obtained by using the polarization unit shown in Fig. 17. Among them, the polarization direction in the P1-P2 direction is perpendicular to the receiving surface, so S light can pass and P light is blocked; and the polarization direction in the P3-P4 direction is parallel to the receiving surface, so P light can pass through and S light is blocked . But the energy of S light is greater than that of P light. Therefore, the sharpness of the fingerprint image in the P1-P2 direction is significantly higher than the sharpness of the fingerprint image in the P3-P4 direction. In other directions, the clarity is somewhere in between.

It can be seen that for 3D fingerprints, when the angles between the different polarization directions and the inclined receiving surface are different, the components of the S wave and the P wave in the optical signal in the different polarization directions received by the image acquisition unit are different, so the different polarizations There is also a difference between the sharpness of the fingerprint image in the direction.

However, for a 2D fake fingerprint, as shown in FIG. 21, for example, the 2D fingerprint 360 has no valleys and ridges, and uses white and black stripes to forge the actual valleys and ridges. Among them, the black stripes will absorb the incident light, while the white stripes reflect the incident light. Since 2D fingerprints are usually carried on rough surfaces such as paper and photos, the reflection of light at the white stripes is dominated by diffuse reflection, and the reflected light basically does not include S light and P light. Therefore, the energy of the optical signal in each polarization direction is approximate. For 2D fingerprints, the clarity of the fingerprint image in all directions is the same.

The reflection at the valley of the 3D fingerprint shown in FIG. 18 is interface reflection, so the reflected light includes S light and P light, and the resolution of the fingerprint image corresponding to the polarization direction in which more S light is transmitted on the polarization unit 330 is high. The sharpness of the fingerprint image corresponding to the polarization direction of more P light. The reflection at the valley shown in FIG. 21 is diffuse reflection, so the reflected light is close to natural light, and its attenuation in each polarization direction is the same, so the resolution of the fingerprint image corresponding to each polarization direction is similar. It can be judged whether the clarity of the fingerprint image in different polarization directions is the same, to judge whether the fingerprint of the finger is a 3D fingerprint or a 2D fingerprint. When the fingerprint is a forged 2D fake fingerprint, the sharpness of the fingerprint image is relatively uniform; when the fingerprint is a 3D fingerprint, the sharpness of the fingerprint image is different in different polarization directions.

In Manner 2, the image acquisition unit 320 may include one sensor, such as shown in FIGS. 1A and 1B; the image acquisition unit 320 may also include multiple sensors, such as shown in FIGS. 2A and 2B.

When the image acquisition unit 320 includes multiple sensors, the number of the light guide layer 310 is multiple. The multiple light guide layers 310 are used to guide light signals in the target direction to the multiple sensors, respectively.

When the image acquisition unit 320 includes a sensor, a light guide layer 310 may be provided above the sensor. The light guide layer 310 is used to guide the light signal in the target direction to the sensor.

Wherein, each light guide layer 310 may be the light guide layer as described in Mode 1.

For example, the light guide layer 310 includes: a microlens array 311, which includes a plurality of microlenses for condensing the optical signal; and, at least one light blocking layer 312, which is sequentially disposed on the microlens array Below 311, each light blocking layer includes a plurality of openings respectively corresponding to the plurality of microlenses. Wherein, the direction of the connection line of the openings corresponding to the same microlens in each light blocking layer is the target direction.

For another example, the light guide layer 310 includes an array of light guide channels 313, and the light guide channels are used to guide the light signal in the target direction to the image acquisition unit 320.

The light guide channel array 313 includes a plurality of light guide channels, and the light guide channels are arranged obliquely. Wherein, the tilt direction of the light guide channel is the target direction. The light guide channel may be formed of, for example, air through holes or light-transmitting materials.

Alternatively, the light guide channel array 313 includes a plurality of optical fibers, and the optical fibers are arranged vertically. The optical signal in the target direction is transmitted in the optical fiber based on total reflection.

For another example, the light guide layer 310 includes an optical functional film layer 314 for transmitting light signals in the target direction and blocking light signals in other directions. The optical function film layer 314 may be, for example, a grating film or a prism film.

It should be understood that, for the structure of the light guide layer 310 here, reference may be made to the aforementioned related descriptions of FIGS. 5 to 12, and for the sake of brevity, details are not repeated here.

Optionally, in the embodiment of the present application, the fingerprint detection device 300 further includes a processor, configured to determine whether the fingerprint image is a 3D fingerprint image according to the sharpness of the fingerprint image in different regions.

For example, in the fingerprint image, when the resolution of the region corresponding to the optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles is different, it is determined that the fingerprint is a 3D fingerprint; and/or, In the fingerprint image, when the resolution of the area corresponding to the optical signal whose receiving surface and the polarization direction are at different angles is the same, it is determined that the fingerprint is a forged 2D fingerprint.

The processor may be a processor of a terminal device, for example, the main control of the terminal device; the processor may also be a processor integrated in the pattern detection apparatus 300. There is no limitation here.

Optionally, in the embodiment of the present application, the fingerprint detection device 300 further includes: a filter layer, which is provided in the light path between the display screen and the image acquisition unit 320, and is used to filter non-target wavelength bands. Optical signal, so that the optical signal of the target wavelength band is transmitted to the image acquisition unit 320.

Wherein, the filter layer is arranged in the light path between the display screen and the image acquisition unit 320. For example, the filter layer is disposed above the light guide layer 310; or the filter layer is disposed above the image acquisition unit 320, such as the filter layer 370 shown in FIGS. 5 to 7.

The filter layer may be an independently formed filter layer, for example, a filter layer formed by using blue crystal or blue glass as a carrier; it may also be a coating formed on any surface of the light path, for example, on the surface of a pixel , The surface of any layer of the transparent medium layer, or the surface of the micro lens is coated with a film to form a filter layer.

Optionally, in the embodiment of the present application, the fingerprint detection device 300 further includes: a medium and a metal layer, which may include a connection circuit with the pixel.

For example, the medium and metal layer can be arranged above the pixel, this method is Front Side Illumination (FSI); the medium and metal layer can also be arranged below the pixel, this method is Back Side Illumination (Back Side Illumination). Illumination, BSI).

An embodiment of the present application also provides an electronic device, which includes: a display screen and the fingerprint detection device 300 in the foregoing various embodiments of the present application.

The display screen may be an ordinary non-folding display screen, or may be a foldable display screen or called a flexible display screen.

As an example and not a limitation, the electronic devices in the embodiments of the present application may be portable or mobile computing devices such as terminal devices, mobile phones, tablet computers, notebook computers, desktop computers, game devices, in-vehicle electronic devices, or wearable smart devices, and Electronic databases, automobiles, bank automated teller machines (Automated Teller Machine, ATM) and other electronic equipment. The wearable smart device includes full-featured, large-sized, complete or partial functions that can be achieved without relying on smart phones, such as smart watches or smart glasses, etc., and only focus on a certain type of application function, and need to cooperate with other devices such as smart phones Use, such as various types of smart bracelets, smart jewelry and other equipment for physical sign monitoring.

It should be noted that, under the premise of no conflict, the various embodiments described in this application and/or the technical features in each embodiment can be combined with each other arbitrarily, and the technical solutions obtained after the combination should also fall within the protection scope of this application. .

It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than limiting the scope of the embodiments of the present application. Those skilled in the art can base on the above-mentioned embodiments. Various improvements and modifications are made, and these improvements or modifications fall within the scope of protection of the present application.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application. Should be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (27)

1. A fingerprint detection device, characterized in that it is arranged under the display screen of an electronic device, and the device includes:

   The light guide layer is used to guide the inclined light signal incident on the finger above the display screen and returning via the finger to the image acquisition unit;

   The image acquisition unit is configured to receive the optical signal to acquire a fingerprint image of the finger, wherein a polarization unit is provided in the optical path between the finger and the image acquisition unit, and the image acquisition unit receives The optical signal includes an optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles, so as to determine whether the fingerprint image is a 3D fingerprint image.
2. The device according to claim 1, wherein the polarization unit comprises a polarization direction, and the light guide layer is used to guide the optical signals in multiple directions to the image acquisition unit, wherein the The angles between the receiving surface of the optical signal in multiple directions and the polarization direction are different.
3. The apparatus according to claim 2, wherein the multiple directions include a first direction and a second direction, wherein the receiving surface of the optical signal in the first direction is perpendicular to the polarization direction, and the first direction The receiving surface of the two-directional optical signal is parallel to the polarization direction.
4. The device according to claim 2 or 3, wherein the image acquisition unit comprises a plurality of sensors, the number of the light guide layers is more than one, and the plurality of light guide layers respectively correspond to the plurality of sensors. Direction, and used to guide the light signals in the corresponding directions to the multiple sensors respectively.
5. The device according to claim 4, wherein the light guide layer comprises:

   A microlens array, including a plurality of microlenses, for converging the optical signal;

   At least one light-blocking layer is sequentially arranged under the microlens array, and each light-blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein each light-blocking layer corresponds to the same microlens The connection direction of the opening is the direction corresponding to the light guide layer.
6. The device according to claim 4, wherein the light guide layer comprises an array of light guide channels, and the array of light guide channels comprises:

   A plurality of light guide channels, the light guide channels are arranged obliquely, and the inclination direction of the light guide channel is the direction corresponding to the light guide layer; or,

   A plurality of optical fibers are arranged vertically, and optical signals in a direction corresponding to the light guide layer are transmitted in the optical fibers based on total reflection.
7. The device according to claim 4, wherein the light guide layer comprises:

   The optical function film layer is used to transmit light signals in the direction corresponding to the light guide layer and block the light signals in other directions.
8. The device according to claim 2 or 3, wherein the image acquisition unit includes a sensor, the number of the light guide layer is one, the light guide layer includes a plurality of regions, and the plurality of regions respectively Corresponding to the multiple directions, a portion of the light guide layer located in each area is used to guide the light signal in the corresponding direction to the sensor.
9. The device according to claim 8, wherein the part of the light guide layer located in each area comprises:

   A microlens array, including a plurality of microlenses, for converging the optical signal;

   At least one light-blocking layer is sequentially arranged under the microlens array, and each light-blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein the openings in each light-blocking layer corresponding to the same microlens The direction of the line of the hole is the direction corresponding to the area.
10. The device according to claim 8, wherein the part of the light guide layer located in each area comprises:

    A plurality of light guide channels, the light guide channels are arranged obliquely, and the inclination direction of the light guide channels is the direction corresponding to the area; or,

    A plurality of optical fibers are arranged vertically, and the optical signal in the direction corresponding to the area is transmitted in the optical fiber based on total reflection.
11. The device according to claim 8, wherein the part of the light guide layer located in each area comprises:

    The optical function film layer is used to transmit light signals in the direction corresponding to the region and block the light signals in other directions.
12. The device according to claim 1, wherein the polarization unit comprises a plurality of polarization directions, and the light guide layer is used to guide the optical signal in the target direction to the image acquisition unit, wherein The angles between the receiving surface of the optical signal in the target direction and the multiple polarization directions are different.
13. The device of claim 12, wherein the plurality of polarization directions form a centrally symmetric pattern.
14. The device according to claim 13, wherein the centrally symmetric pattern is circular or square.
15. The device according to any one of claims 12 to 14, wherein the image acquisition unit comprises a plurality of sensors, the number of the light guide layer is multiple, and the plurality of light guide layers are used to The optical signals in the target direction are respectively guided to the plurality of sensors.
16. The device according to any one of claims 12 to 14, wherein the image acquisition unit comprises a sensor, the number of the light guide layer is one, and the light guide layer is used to direct the target direction The light signal on the sensor is guided to the sensor.
17. The device according to claim 15 or 16, wherein the light guide layer comprises:

    A microlens array, including a plurality of microlenses, for converging the optical signal;

    At least one light-blocking layer is sequentially arranged under the microlens array, and each light-blocking layer includes a plurality of openings corresponding to the plurality of microlenses, wherein the openings in each light-blocking layer corresponding to the same microlens The direction of the line of the hole is the target direction.
18. The device according to claim 15 or 16, wherein the light guide layer comprises a light guide channel array, and the light guide channel array comprises:

    Multiple light guide channels, the light guide channels are arranged obliquely, and the inclination direction of the light guide channels is the target direction; or,

    A plurality of optical fibers are arranged vertically, and the optical signal in the target direction is transmitted in the optical fiber based on total reflection.
19. The device according to claim 15 or 16, wherein the light guide layer comprises a light guide channel array, and the light guide channel array comprises:

    The optical function film layer is used to transmit the optical signal in the target direction and block the optical signal in other directions.
20. The device according to any one of claims 1 to 19, wherein the polarization unit is located in the display screen.
21. The device according to any one of claims 1 to 20, wherein the polarization unit is located above the light guide layer.
22. The device according to claim 21, wherein the polarization unit is formed on the upper surface of the light guide layer or the image acquisition unit by coating, or the polarization unit is pasted on the guide by optical glue. The optical layer or the upper surface of the image acquisition unit.
23. The device according to any one of claims 1-22, wherein the device further comprises:

    The processor is configured to determine whether the fingerprint image is a 3D fingerprint image according to the sharpness of the fingerprint image in different regions.
24. The device according to claim 23, wherein the processor is specifically configured to:

    In the fingerprint image, when the resolution of the area corresponding to the optical signal whose receiving surface and the polarization direction of the polarization unit are at different angles is different, determining that the fingerprint image is a 3D fingerprint image;

    When the definitions are the same, it is determined that the fingerprint image is not a 3D fingerprint image.
25. The device according to any one of claims 1 to 24, wherein the device further comprises:

    The filter layer is arranged in the optical path between the display screen and the image acquisition unit, and is used to filter the optical signal in the non-target wavelength band, so that the optical signal in the target wavelength band is transmitted to the image acquisition unit.
26. The device of claim 25, wherein the filter layer is disposed above the light guide layer.
27. An electronic device, characterized in that it comprises:

    Display screen; and,

    The fingerprint detection device according to any one of claims 1 to 26.

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