WO2021022488A1 - 指纹检测的装置和电子设备 - Google Patents

指纹检测的装置和电子设备 Download PDF

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Publication number
WO2021022488A1
WO2021022488A1 PCT/CN2019/099487 CN2019099487W WO2021022488A1 WO 2021022488 A1 WO2021022488 A1 WO 2021022488A1 CN 2019099487 W CN2019099487 W CN 2019099487W WO 2021022488 A1 WO2021022488 A1 WO 2021022488A1
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WO
WIPO (PCT)
Prior art keywords
light
image acquisition
acquisition unit
optical
light guide
Prior art date
Application number
PCT/CN2019/099487
Other languages
English (en)
French (fr)
Inventor
谢浩
杜灿鸿
汪海翔
Original Assignee
深圳市汇顶科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 深圳市汇顶科技股份有限公司 filed Critical 深圳市汇顶科技股份有限公司
Priority to PCT/CN2019/099487 priority Critical patent/WO2021022488A1/zh
Priority to CN201980004078.1A priority patent/CN111133442B/zh
Priority to CN201980004253.7A priority patent/CN111095281B/zh
Priority to PCT/CN2019/112778 priority patent/WO2021022680A1/zh
Priority to CN201921791947.3U priority patent/CN210605741U/zh
Priority to EP20803435.5A priority patent/EP3800579B1/en
Priority to CN202021792452.5U priority patent/CN213069852U/zh
Priority to KR1020207029218A priority patent/KR102462669B1/ko
Priority to CN202080001560.2A priority patent/CN111801688B/zh
Priority to CN202020066554.2U priority patent/CN211529172U/zh
Priority to PCT/CN2020/071511 priority patent/WO2021022789A1/zh
Priority to US17/033,761 priority patent/US11176348B2/en
Publication of WO2021022488A1 publication Critical patent/WO2021022488A1/zh

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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
    • 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
    • G06V10/143—Sensing or illuminating at different wavelengths
    • 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
    • G06V10/147—Details of sensors, e.g. sensor lenses
    • 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
    • G06V40/1324—Sensors therefor by using geometrical optics, e.g. using prisms

Definitions

  • the embodiments of the present application relate to the field of fingerprint detection, and more specifically, to a fingerprint detection device and electronic equipment.
  • the fingerprint detection technology under the optical screen is to collect the light signal formed by the reflection or transmission of light on the finger.
  • the optical signal carries the fingerprint information of the finger, so as to realize the fingerprint detection under the screen.
  • special fingers such as relatively dry fingers, there is an air gap between the fingerprint and the display screen. The air gap will cause the reflection of the ridges and valleys of the fingerprint to become smaller, which reduces the contrast of the fingerprint image and affects the fingerprint detection performance. .
  • the embodiments of the present application provide a fingerprint detection device and electronic equipment, which can improve fingerprint detection performance.
  • a fingerprint detection device which is suitable for under the display screen to realize under-screen optical fingerprint detection, and the device includes:
  • the first light guide layer is arranged above the image acquisition unit and is used to transmit the oblique light signal incident on the finger above the display screen and returned via the finger to the image acquisition unit, wherein the oblique light
  • the signal includes a reflected light signal and a transmitted light signal from the finger.
  • the reflected light signal is attenuated after passing through a linear polarization unit in the optical path between the finger and the image acquisition unit, so that it reaches the image acquisition unit.
  • the proportion of the transmitted light signal of the unit is relatively increased;
  • the pixels located under the first light guide layer in the image acquisition unit are used to receive the oblique light signal, and the oblique light signal is used to obtain a fingerprint image of the finger.
  • the linear polarization unit is integrated inside the display screen and located above the organic light emitting diode OLED layer of the display screen.
  • the linear polarization unit is located between the display screen and the image acquisition unit.
  • the polarization direction of the linear polarization unit is perpendicular to the incident surface of the inclined optical signal; or, the polarization direction of the linear polarization unit is parallel to the incident surface of the inclined optical signal; or The angle between the polarization direction of the linear polarization unit and the incident surface of the oblique optical signal is 45°.
  • the tilt angle of the tilted optical signal is less than or equal to the Brewster angle.
  • the first light guide layer includes: a microlens array formed by a plurality of microlenses for converging the oblique light signal; at least one light blocking layer is provided on the Below the microlens array, each light blocking layer includes a plurality of openings corresponding to the plurality of microlenses, and the oblique light signal condensed by each microlens passes through different light blocking layers and each The corresponding opening of the micro lens reaches the image acquisition unit.
  • the projection of the condensing surface of each microlens in the microlens array on a plane perpendicular to its optical axis is a rectangle or a circle.
  • the curvature of the condensing surface of each microlens in the microlens array is the same in all directions.
  • the last light blocking layer of the at least one light blocking layer is integrated in the image acquisition unit.
  • the apertures of the openings corresponding to the same microlens in different light blocking layers are sequentially reduced from top to bottom.
  • the device further includes: a transparent medium layer for connecting the microlens array, the at least one light blocking layer, and the image acquisition unit, and filling the at least one light blocking layer The opening in the layer.
  • the first light guide layer includes: an optical function film layer, which is used to select the tilt light signal from the light signals in various directions returned by the finger, and to set the tilt The optical signal is transmitted to the image acquisition unit.
  • the optical function film layer is further used to refract the selected oblique light signal so that the oblique light signal is perpendicularly incident on the pixels of the image acquisition unit.
  • the optical function film layer is a grating film or a prism film.
  • the optical function film layer is integrated in the image acquisition unit, or is disposed above the image acquisition unit as a relatively independent device from the image acquisition unit.
  • the first light guide layer includes: a light guide channel array formed by a plurality of light guide channels.
  • the multiple light guide channels are formed by optical fibers, air through holes, or light-transmitting materials.
  • the first light guide layer is arranged horizontally, and the multiple light guide channels are inclined with respect to the surface of the first light guide layer to guide the inclined light signal to the Image acquisition unit.
  • the multiple light guide channels are formed by optical fibers, the first light guide layer is arranged horizontally, and the multiple light guide channels are perpendicular to the surface of the first light guide layer.
  • the oblique light signal reaches the image acquisition unit after at least one total reflection in each light guide channel of the plurality of light guide channels.
  • the plurality of light guide channels are perpendicular to the surface of the first light guide layer, and the first light guide layer is arranged obliquely to guide the oblique light signal to the image Collection unit.
  • the device further includes: a second light guide layer, which is arranged above the image acquisition unit, and is used to transmit the light signal in the second direction returned by the finger to the image Acquisition unit; wherein, the pixels located under the second light guide layer in the image acquisition unit are used to receive the optical signal in the second direction, and the optical signal in the second direction is used to obtain the fingerprint of the finger An image, wherein the oblique optical signal transmitted by the first light guide layer is an optical signal in a first direction, and the second direction is different from the first direction.
  • the second direction is a vertical direction or an oblique direction.
  • the device further includes: a filter layer, which is arranged in the optical path between the display screen and the image acquisition unit, and is used to filter light signals of non-target wavelength bands and pass through the target wavelength bands.
  • a filter layer which is arranged in the optical path between the display screen and the image acquisition unit, and is used to filter light signals of non-target wavelength bands and pass through the target wavelength bands. Light signal.
  • the filter layer is a coating formed on the surface of any layer in the optical path.
  • the image acquisition unit includes one optical fingerprint sensor, or includes multiple optical fingerprint sensors spliced together.
  • a fingerprint detection device which is suitable for under the display screen to realize the under-screen optical fingerprint detection, and the device includes:
  • the first light guide layer is arranged above the image acquisition unit, and is used to transmit the light signal in the first direction incident on the finger above the display screen and returned by the finger to the image acquisition unit;
  • the second light guide layer is arranged above the image acquisition unit, and is used to transmit the light signal in the second direction returned by the finger to the image acquisition unit;
  • pixels located under the first light guide layer in the image acquisition unit are used to receive light signals in the first direction, and the image acquisition unit is located under the second light guide layer
  • the pixels in the second direction are used to receive the optical signal in the second direction, and the optical signal in the first direction and the optical signal in the second direction are used to obtain the fingerprint image of the finger.
  • the two directions are different.
  • the oblique light signal includes a reflected light signal and a transmitted light signal from the finger, wherein the reflected light signal passes through the optical path between the finger and the image acquisition unit
  • the linear polarization unit in the image pickup unit is then attenuated, so that the proportion of the transmitted light signal reaching the image acquisition unit is relatively increased.
  • the first direction is an oblique direction
  • the second direction is a vertical direction or an oblique direction
  • the incident surface of the optical signal in the first direction is perpendicular to the polarization direction of the linear polarization unit; or, the incident surface of the optical signal in the first direction is perpendicular to the linear polarization unit.
  • the angle between the incident surface of the optical signal in the first direction and the polarization direction of the linear polarization unit is 45°.
  • the linear polarization unit is integrated inside the display screen and located above the OLED layer of the display screen.
  • the linear polarization unit is located between the display screen and the image acquisition unit.
  • the tilt angle of the tilted optical signal is less than or equal to the Brewster angle.
  • an electronic device including:
  • the fingerprint detection device in the first aspect or any possible implementation of the first aspect or the fingerprint detection device in the second aspect or any possible implementation of the second aspect.
  • oblique light is used for fingerprint detection, and a linear polarization unit is used, so that the reflected light in the light after passing through the linear polarization unit can be attenuated, thereby relatively increasing the transmission light signal of the finger reaching the image acquisition unit
  • the ratio improves the fingerprint detection performance, especially for special fingers such as dry fingers.
  • FIG. 1A and FIG. 2A are schematic diagrams of the structure of electronic equipment to which the present application can be applied.
  • Figures 1B and 2B are schematic cross-sectional views of the electronic device shown in Figures 1A and 2A along the A-A' direction, respectively.
  • Fig. 3 is a schematic block diagram of a fingerprint detection device according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of fingerprint detection based on the reflected light signal and the transmitted light signal of the finger.
  • 5A and 5B are schematic diagrams of the relationship between the distance between the finger and the display screen and the contrast of the fingerprint image.
  • Fig. 6 is a schematic diagram of a possible linear polarization unit according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of a possible first light guide layer according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a possible first light guide layer according to an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a possible first light guide layer in an embodiment of the present application.
  • FIGS. 10A and 10B are schematic diagrams of a possible first light guide layer according to an embodiment of the present application.
  • 11A, 11B, and 11C are schematic diagrams of a possible first light guide layer according to an embodiment of the present application.
  • FIG. 12 is a schematic block diagram of a fingerprint detection device according to another embodiment of the present application.
  • 13A, 13B and 13C are schematic diagrams of fingerprint detection based on light from different directions.
  • FIG. 14 is a schematic diagram of a possible second light guide layer according to an embodiment of the present application.
  • FIG. 15 is a schematic diagram of a possible second light guide layer according to an embodiment of the present application.
  • 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
  • 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.
  • 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.
  • 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 fingerprint detection technology under the optical screen uses the light returned from the top surface of the device display component to perform fingerprint sensing and other sensing operations.
  • the returned light carries the information of the object (for example, a finger) in contact with the top surface.
  • a 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.
  • FIGS. 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
  • FIG. 1B and FIG. 2B are partial cross-sectional schematic 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.
  • 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 (may also be referred to as pixels, photosensitive pixels, pixel units, etc.).
  • the area where the sensing array 133 is located or the sensing area thereof is the fingerprint detection area 103 of the optical fingerprint module 130 (also referred to as fingerprint collection area, fingerprint recognition area, etc.). As shown in FIG. 1, the fingerprint detection area 103 is located in the display area of the display screen 120.
  • the optical fingerprint module 130 may also be arranged in other positions, such as the side of the display screen 120 or the non-transparent area of the edge of the electronic device 10, and the optical fingerprint module 130 The optical signal of 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.
  • 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, for example, through a light path design such as lens imaging, a reflective folding light path design, or other light paths such as light convergence or reflection.
  • the design can make the area of the fingerprint detection area 103 of the optical fingerprint module 130 larger than the area of the sensing array 133 of the optical fingerprint module 130.
  • the fingerprint detection area 103 of the optical fingerprint module 130 can also be designed to be substantially the same as the area of the sensing array of the optical fingerprint module 130.
  • 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.
  • 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, such as an optical imaging chip Or an optical fingerprint sensor.
  • 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 aforementioned 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 (also called an optical path guide structure), and other optical elements.
  • the filter layer can be used to filter out 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 sensing array 133 for optical detection.
  • the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component.
  • the optical component 132 and the optical detection part 134 can be packaged in the same optical fingerprint chip, or the optical component 132 can 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.
  • the light guide layer of the optical component 132 has a variety of implementation schemes.
  • the light guide layer may specifically be a collimator layer made on a semiconductor silicon wafer, which has multiple collimator units.
  • the collimating unit may be specifically a small hole.
  • the reflected light reflected from the finger the light that is perpendicularly incident on the collimating unit can pass through and be received by the optical sensing unit below it, and then enter The light with an excessively large angle is attenuated by multiple reflections inside the collimating unit. Therefore, each optical sensing unit can basically only receive the reflected light reflected by the fingerprint pattern directly above it, so the sensing array 133 is The fingerprint image of the finger can be detected.
  • the light guide layer may also be an optical lens (Lens) layer, which has one or more lens units, such as a lens group consisting of one or more aspheric lenses, which is used to The reflected light reflected by 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.
  • 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.
  • 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.
  • other optical film layers may be formed between the microlens layer and the sensing unit, such as a dielectric layer or a passivation layer.
  • a light blocking layer (or called a light blocking layer, a light blocking layer, etc.) with micro holes (or called openings) may also be included between the micro lens layer and the sensing unit, wherein the micro The hole is formed between the corresponding micro lens and the sensing unit, the light blocking layer can block the optical interference between the adjacent micro lens and the sensing unit, and make the light corresponding to the sensing unit converge through the micro lens To the inside of the micropore and transfer to the sensing unit through the micropore for optical fingerprint imaging.
  • a micro lens layer may be further provided above or below the collimator layer or the optical lens layer.
  • 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.
  • 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.
  • 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.
  • OLED Organic Light-Emitting Diode
  • Micro-LED Micro-LED
  • 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.
  • the display screen 120 emits a beam of light 111 to the target 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.
  • the above-mentioned reflected light and scattered light are 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.
  • the optical fingerprint detection function is implemented in the electronic device 10.
  • 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.
  • 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.
  • 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.
  • 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.
  • the electronic device 10 may also include a transparent protective cover plate, which may be a glass cover plate or a sapphire cover plate, which is located above the display screen 120 and covers the front surface of the electronic device 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.
  • a transparent protective cover plate which may be a glass cover plate or a sapphire 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.
  • 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 electronic device 10 through the circuit board 150. Control unit, etc.
  • 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 perform fingerprint input 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.
  • the optical fingerprint module 130 may specifically 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 together constitute the fingerprint detection area 103 of the optical fingerprint module 130.
  • 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.
  • the multiple 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 device 130.
  • the optical component 132 may have multiple light guide layers, and each light guide layer corresponds to an optical fingerprint sensor, and is attached to each Set above the corresponding optical fingerprint sensor.
  • 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.
  • the optical assembly 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 display.
  • the screen 120 and the light guide layer are mainly used to isolate the influence of external interference light on optical fingerprint detection.
  • 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 filter can be specific to each The optical fingerprint sensors are separately arranged to filter out interference light, or a large-area filter can also be used to simultaneously cover the multiple optical fingerprint sensors.
  • the light guide layer may also adopt an optical lens (Lens), and a small hole can be formed through a light-shielding material above the optical lens to cooperate with the optical lens to converge fingerprint detection light to an optical fingerprint sensor below to realize fingerprint imaging.
  • 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 achieve light convergence and fingerprint imaging.
  • 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.
  • the number, size, and arrangement of the fingerprint sensors shown above are only examples and can be adjusted according to actual needs.
  • the number of the plurality of fingerprint sensors may be 2, 3, 4, 5, etc., and the plurality of fingerprint sensors may be distributed in a square or circular shape.
  • the embodiments of the present application can be applied to the detection of various types of fingers, and are particularly suitable for the detection of dry fingers.
  • the so-called dry fingers refer to dry fingers or clean fingers.
  • the current fingerprint detection solution using vertical light has a poor effect on dry finger fingerprint detection, and the fingerprint detection solution provided by the embodiment of the present application can improve the fingerprint detection performance on dry fingers.
  • FIG. 3 shows a schematic diagram of a fingerprint detection device 300 according to an embodiment of the present application.
  • the device 300 includes a first light guide layer 310 and an image acquisition unit 320.
  • image acquisition unit 320 reference may be made to the related description of the above-mentioned light detection part 134, which is not repeated in this embodiment.
  • the first light guide layer 310 is disposed above the image acquisition unit 320.
  • the first light guide layer 310 is used to transmit the oblique light signal incident on the finger above the display screen and returning via the finger to the image acquisition unit 320.
  • the optical signal returned by the finger includes the reflected optical signal and the transmitted optical signal from the finger.
  • the reflected light signal is attenuated after passing through the linear polarization unit 330, so that the proportion of the transmitted light signal reaching the image acquisition unit 320 is relatively increased.
  • the linear polarization unit 330 is provided in the optical path between the finger and the image acquisition unit 320.
  • the linear polarization unit 330 is used to attenuate the reflected light signal, thereby relatively increasing the proportion of the transmitted light signal reaching the image acquisition unit 320.
  • the linear polarization unit 330 may be integrated inside the display screen to be a part of the display screen, for example, located above the OLED layer of the display screen; or, the linear polarization unit 330 is located on the first light guide layer 310 Or, the linear polarization unit 330 is integrated in the image acquisition unit 320, so as to be a part of the image acquisition unit 320, for example, located in the pixel array of the image acquisition unit 320 Above.
  • the image acquisition unit 320 includes one optical fingerprint sensor, or includes multiple optical fingerprint sensors spliced together, for example, as shown in FIGS. 2A and 2B.
  • Each optical fingerprint sensor includes a pixel array formed by a plurality of pixels.
  • the pixels located under the first light guide layer 310 in the image acquisition unit 320 are used to receive the oblique light signal, and the oblique light signal is used to obtain a fingerprint image of the finger.
  • the optical signal incident on the finger above the display screen 340 and returning via the finger includes two parts, one part is the reflected light signal from the finger, and the other part is the transmitted light signal from the finger.
  • the fingerprint image obtained by using the reflected light signal shown on the left is shown as bright valleys and dark ridges (positive color fingerprints).
  • the ridge becomes darker, and the contrast between the ridge and valley becomes better.
  • the fingerprint image obtained with the transmitted light signal shown on the right shows dark ridges and bright ridges (reverse color fingerprints).
  • Figures 5A and 5B show the relationship between the distance between the finger and the display screen and the contrast of the fingerprint image.
  • Figure 5A shows the fingerprint detection using vertical light signals
  • Figure 5B shows the fingerprint detection using oblique light.
  • Fingerprint detection The abscissa is the distance between the finger and the display screen, and the ordinate is the contrast of the fingerprint image.
  • the reflected light imaging is dominant at this time, and the fingerprint image shows the characteristics of bright valleys and dark ridges. At this time, the fingerprint detection performance of normal fingers is better.
  • the contact between the fingerprint and the display gradually becomes worse, as the distance between the ridge and the display becomes larger, the effect of reflected light imaging gradually weakens, and the transmitted light imaging gradually becomes dominant, and the fingerprint image presents the characteristics of dark valleys and bright ridges. .
  • the contrast of the fingerprint image is the lowest, and this stage is called the transition zone. In this transition zone, the fingerprint images of the reflected light imaging and the transmitted light imaging cancel each other out, so that the final fingerprint image of the finger has a poor contrast.
  • Reflected light imaging is more sensitive to changes in the distance between the finger and the display screen, while transmitted light imaging is less sensitive to changes in the distance. Therefore, when detecting dry fingers, it is expected that the transmitted light imaging will be dominant, and the proportion of the transmitted light will be increased to reduce the transition zone, thereby improving the fingerprint detection performance.
  • oblique light is used for fingerprint detection, and the reflected light signal of the finger is attenuated by the linear polarization unit to relatively increase the proportion of the transmitted light signal reaching the image acquisition unit, thereby improving the fingerprint detection performance, especially Recognition performance for special fingers such as dry fingers.
  • the angle between the polarization direction of the linear polarization unit 330 and the incident surface of the oblique optical signal is between 0° and 90°.
  • the polarization direction of the linear polarization unit 330 is perpendicular to the incident surface of the oblique optical signal, parallel to the incident surface of the oblique optical signal, or the included angle with the incident surface of the oblique optical signal is 45°.
  • FIG. 6 shows a possible linear polarization unit 330 according to an embodiment of the present application.
  • the linear polarization unit 330 is located above the OLED layer 341 in the display screen 340.
  • the light emitted from the OLED layer 341 passes through the linear polarization unit 330 and then becomes linearly polarized light and irradiates the finger 350 above the cover plate 342.
  • the polarization direction of the transmitted light remains unchanged, so that it can pass through the linear polarization unit 330 and then return, and is guided by the light guide layer 310 to be transmitted to the image acquisition unit 320.
  • the reflected light of the finger 350 since it is incident on the finger 350 obliquely, the reflected light of the finger 350 includes p-wave and s-wave, where the polarization direction of the p-wave is parallel to the incident plane of the light, and the polarization direction of the s-wave It is perpendicular to the incident plane, which is perpendicular to the display screen 340.
  • the polarization polarity of the linear polarization unit 330 is parallel to the incident plane of the oblique light (or called the receiving plane of the oblique light signal), the s-wave in the reflected light from the finger will be attenuated, and only the p-wave can pass through
  • the linear polarization unit 330 then returns and is guided by the light guide layer 310 and then transmitted to the image acquisition unit 320.
  • the polarization polarity of the linear polarization unit 330 is perpendicular to the incident plane, the p-wave in the reflected light of the finger will be attenuated, and only the s-wave can pass through the linear polarization unit 330 and then return and be guided by the light guide layer 310 It is then transmitted to the image acquisition unit 320, as shown in FIG. 6, for example. Regardless of whether the p-wave or s-wave is attenuated, the reflected light signal of the finger is weakened, but the transmitted light signal of the finger remains unchanged. Therefore, relatively speaking, the proportion of the transmitted light signal in the light signal returned by the finger is increased and decreased The transition zone improves the detection performance of dry fingers.
  • the p-wave in the reflected light is usually less than the s-wave. If the incident angle reaches the Brewster angle, there is no p-wave in the reflected light, only s-waves are left. Therefore, the reflected light is completely polarized and its polarization direction is perpendicular to The plane of incidence. When the incident angle exceeds Brewster's angle, both s-wave and p-wave increase until they reach the total reflection angle and they are all reflected. Therefore, preferably, if the tilt angle of the tilt light signal returned by the finger is less than or equal to the Brewster angle, the reflected light signal returned by the finger can be made as few as possible.
  • the embodiment of the present application provides three possible implementation manners of the first light guide layer 310. A detailed description will be given below with reference to FIGS. 7 to 12.
  • the first light guide layer 310 includes a micro lens array formed by a plurality of micro lenses 311, and at least one light blocking layer 312 disposed under the micro lens array.
  • each microlens 311 is used to converge the tilt light signal returned by the finger.
  • Each light-blocking layer 312 of the at least one light-blocking layer 312 includes a plurality of openings 313 corresponding to the plurality of microlenses 311, and the oblique light signal condensed by each microlens 311 passes through different light-blocking layers.
  • the opening 313 in the 312 corresponding to the micro lens 311 reaches the image acquisition unit 320.
  • the projection of the condensing surface of the microlens 311 on a plane perpendicular to the optical axis may be rectangular or circular.
  • the condensing surface of the microlens 311 is a surface for converging light.
  • the condensing surface may be spherical or aspherical.
  • the curvature of the condensing surface in all directions is the same, so that the imaging focus of the micro lens 311 in all directions can be at the same position, thereby ensuring the imaging quality.
  • Each microlens 311 corresponds to a pixel 321 in the image acquisition unit 320, wherein the oblique light signal condensed by the microlens 311 passes through the openings corresponding to the microlens 311 in different light blocking layers to reach the microlens 321.
  • the pixel 321 corresponding to the lens 311.
  • the connection lines of the openings corresponding to each microlens in different light blocking layers should be inclined.
  • the tilt angle is equal to or approximately equal to the tilt angle of the tilted optical signal.
  • the light blocking layer 312 may be provided with one layer or multiple layers.
  • the light blocking layer 312 may be integrated in the image acquisition unit 320, for example, a metal mask is used to form a light blocking layer above the pixel array.
  • the inclination angle of the connection line of the openings corresponding to each microlens in the different light blocking layers is equal to the inclination angle of the inclined light signal returned by the finger .
  • the openings corresponding to the pixel in the plurality of light blocking layers are sequentially offset from top to bottom, so that the pixel 321 can receive the oblique light signal returned by the finger, while blocking light signals in other directions.
  • the last light-blocking layer of the multiple light-blocking layers may be integrated in the image acquisition unit 320, for example, as shown in FIGS. 8 and 9, when a light-blocking layer is integrated in the image acquisition unit 320, the light-blocking layer The layer has higher reliability.
  • the apertures of the openings in different light blocking layers corresponding to the same microlens are sequentially reduced from top to bottom.
  • the aperture of the aperture in the upper light-blocking layer is set to be larger than the aperture in the lower light-blocking layer, so that more (a certain range of angle) light signals can be guided to the corresponding Pixels.
  • a transparent medium layer is also provided between the micro lens array, the at least one light blocking layer and the image acquisition unit.
  • the transparent medium layer is used to connect the microlens array, the at least one light blocking layer and the pixels in the image acquisition unit, and to fill the openings in the at least one light blocking layer.
  • the transparent medium layer can transmit the optical signal of the target wavelength band (that is, the optical signal of the wavelength band required for fingerprint detection).
  • the transparent dielectric layer may be oxide or nitride.
  • the transparent medium layer may include multiple layers to implement functions such as protection, transition, and buffering respectively.
  • a transition layer can be provided between the inorganic layer and the organic layer to achieve a tight connection; a protective layer can be provided on the easily oxidized layer to achieve protection.
  • the first light guide layer 310 includes an optical function film layer 314, which is used to select the oblique light signal from the light signals in various directions returned by the finger, and transmit the oblique light signal to the image acquisition Unit 320.
  • the optical function film layer 314 may be, for example, a grating film or a prism film.
  • the optical function film layer 314 can transmit oblique light 316 at a specific angle and transmit the light 316 to the image acquisition unit 320, while blocking light at other angles.
  • the optical function film layer 314 can also be used to refract the oblique light signal, so that the oblique light signal can be incident on the pixels of the image acquisition unit 320 perpendicularly.
  • the optical function film layer 314 can transmit oblique light 316 at a specific angle, and refract the light 316 to make it incident on the image acquisition unit 320 perpendicularly. Since the pixels of the image acquisition unit 320 have the highest quantum efficiency for the light received vertically, the optimal photoelectric conversion efficiency can be obtained in this way, and the fingerprint detection performance is further improved.
  • the optical function film layer 314 may be integrated in the image acquisition unit 320 or disposed above the image acquisition unit 320 as a relatively independent device from the image acquisition unit 320.
  • the first light guide layer 310 includes a light guide channel array formed by a plurality of light guide channels 315.
  • the light guide channel 315 may be formed of, for example, an optical fiber, an air through hole, or a light-transmitting material.
  • the first light guide layer 310 is arranged horizontally, and the plurality of light guide channels 315 are inclined relative to the surface of the first light guide layer 310 to guide the inclined light signal to the image Collection unit 320.
  • the first light guide layer 310 is arranged parallel to the display screen 340, and the light guide channel 315 is an inclined channel whose inclination angle is the same as that of the inclined light signal returned by the finger, so that the inclined light The signal can pass through the light guide channel 315 to reach the image acquisition unit 320, while light signals in other directions are blocked.
  • the plurality of light guide channels 315 are perpendicular to the surface of the first light guide layer 310, and the first light guide layer 310 is arranged obliquely to guide the oblique light signal to the The image acquisition unit 320.
  • the light guide channel 315 is a vertical channel, which is perpendicular to the surface of the first light guide layer 310.
  • the first light guide layer 310 can be arranged obliquely so that the inclination angle of the The oblique angles of the oblique light signals are the same, so that the oblique light signals can reach the image acquisition unit 320 through the light guide channel 315, while light signals in other directions are blocked.
  • the first light guide layer 310 is arranged horizontally, the plurality of light guide channels 315 are perpendicular to the surface of the first light guide layer 310, and the oblique light signal is in the plurality of Each light guide channel 315 in the light guide channel 315 reaches the image acquisition unit 320 after at least one total reflection.
  • the first light guide layer 310 is arranged parallel to the display screen 340, and the light guide channel 315 is a vertical channel, and the light guide channel 315 is an optical fiber. Since the optical fiber can transmit the incident light at a specific angle, the optical fiber can be used to guide the oblique light signal at a specific angle reflected by the finger. After the oblique optical signal enters from one end of the optical fiber 315, multiple total reflections occur in the optical fiber 315, and finally exits from the other end of the optical fiber 315, thereby reaching the image acquisition unit 320.
  • the embodiment of the present application also provides another implementation manner of the fingerprint detection device 300.
  • the fingerprint detection device 300 includes a first light guide layer 320, a second light guide layer 360 and an image acquisition unit 320.
  • the second light guide layer 360 is disposed above the image acquisition unit 320, and is used to transmit the light signal in the second direction returned by the finger to the image acquisition unit 320.
  • the pixels located under the second light guide layer 360 in the image acquisition unit 320 are used to receive the light signal in the second direction, and the light signal in the second direction is used to obtain the fingerprint image of the finger.
  • the oblique optical signal transmitted by the first light guide layer is an optical signal in a first direction, and the second direction is different from the first direction.
  • the fingerprint detection device 300 may include the second light guide layer 360 in addition to the aforementioned first light guide layer 320.
  • the first light guide layer 320 is used to transmit the light signal incident on the finger above the display screen and returned by the finger in the first direction to the image acquisition unit 320; and the second light guide layer 360 The light signal in the second direction used to return the finger is transmitted to the image acquisition unit 320. Since the light signals in different directions can be detected at the same time for fingerprint detection, the fingerprint detection performance is improved.
  • the first direction is different from the second direction.
  • the second direction may be an oblique direction or a vertical direction.
  • the inclination angle of the light in the second direction and the inclination angle of the light in the first direction may be the same or different.
  • the incident surface of the optical signal in the first direction may be perpendicular to the polarization direction of the linear polarization unit 330; or, the incident surface of the optical signal in the first direction may be perpendicular to the linear polarization unit 330.
  • the polarization direction of 330 is parallel; or, the incident surface of the optical signal in the first direction and the polarization direction of the linear polarization unit 330 form a certain angle, for example, 45°, which is not limited in this application.
  • the first direction is an oblique direction, and there is an angle between it and the display screen.
  • FIG. 13A is a top view.
  • the arrow shown can be considered as the incident surface of the light in the first direction in the display screen.
  • the dashed line represents the polarization direction of the linear polarization unit 330.
  • the second direction is the vertical direction, which is perpendicular to the display screen.
  • the oblique light signal in the first direction returned by the finger is transmitted to the image acquisition unit 320 through the first light guide layer 310, and the vertical light signal returned by the finger is transmitted to the image acquisition unit through the second light guide layer 360 Unit 320.
  • the first direction and the second direction are both oblique directions, but the incident surface of the optical signal in the first direction is perpendicular to the polarization direction of the linear polarization unit 330, and the incident surface of the optical signal in the second direction
  • the plane is parallel to the polarization direction of the linear polarization unit 330.
  • 13B is a top view, the arrows shown can be considered as projections of light rays in the first direction and the second direction into the display screen on the incident surface, and the dotted line indicates the polarization direction of the linear polarization unit 330.
  • the incident surface of the optical signal in the first direction is perpendicular to the polarization direction of the linear polarization unit 330, and the angle between the optical signal in the second direction and the polarization direction of the linear polarization unit 330 is 45°.
  • the device 300 may further include more light guide layers, and these light guide layers are respectively used to transmit light signals in different directions to the image acquisition unit 320.
  • these light guide layers are respectively used to transmit light signals in different directions to the image acquisition unit 320.
  • four light guide layers can be provided to guide light from four different directions of A, B, C, and D to the image acquisition unit 320, respectively.
  • different light guide layers are used to transmit light signals in different directions to the image acquisition unit for fingerprint detection, which improves fingerprint detection performance.
  • the main concern is the size of the ridge-valley difference.
  • the contrast of fingerprint images obtained when using oblique light to detect fingerprints is better than when using vertical light to detect fingerprints.
  • the contrast of fingerprint images obtained when using vertical light to detect fingerprints is better than when using oblique light to detect fingerprints.
  • the first light guide layer 310 and the second light guide layer 360 are used to transmit oblique light signals and vertical light signals, part of the fingerprint information of the finger can pass through the first light guide layer.
  • 320 is transmitted to the image acquisition unit 320.
  • the first light guide layer 320 transmits the oblique light signal carrying this part of the fingerprint information to the corresponding pixels, so that a better fingerprint image can be obtained when the finger is dry;
  • Part of the fingerprint information can be transmitted to the image acquisition unit 320 through the second light guide layer 360.
  • the second light guide layer 360 transmits the vertical light signal carrying this part of the fingerprint information to the corresponding pixels, so that it can be acquired when the finger is a normal finger.
  • Better fingerprint image In this way, whether the finger is a dry finger or a normal finger, a better fingerprint image can be obtained, and the fingerprint detection performance of the normal finger and the dry finger is taken into consideration, which improves the success rate of fingerprint detection and improves user experience.
  • the second light guide layer 360 may also be implemented by the above-mentioned method 1, method 2, or method 3.
  • the second light guide layer 360 includes a microlens array and at least one light blocking layer to guide vertical light.
  • the guide of light in a certain direction can be realized by setting the offset of the opening position in the at least one light blocking layer. For example, as shown in FIG.
  • each light blocking layer 362 includes a plurality of openings 363 corresponding to a plurality of microlenses, and different light blocking layers 362 correspond to The openings of the same microlens are arranged vertically from top to bottom, so that the oblique light signal condensed by each microlens 361 passes through the openings corresponding to the microlens 361 in different light-blocking layers, and reaches the image acquisition unit vertically. 320.
  • the lines of the openings corresponding to the microlens 361 in different light blocking layers are perpendicular to the display screen, so that the vertical light signal returned by the finger can reach the pixels 321 of the image acquisition unit 320, and the oblique light is blocked.
  • the second light guide layer 360 includes an optical function film layer 317 to filter the vertical light.
  • the optical function film layer 317 can transmit the vertical light 318 and transmit the light 318 to the image acquisition unit 320, while blocking the oblique light.
  • the vertical light is guided by the light guide channel array.
  • the second light guide layer 360 is arranged parallel to the display screen, and each light guide channel is perpendicular to the surface of the second light guide layer 360, so that the vertical light signal returned by the finger can pass through, while oblique light is blocked.
  • the embodiment of the present application does not limit the relative positions of the first light guide layer 310 and the second light guide layer 360.
  • the first light guide layer 310 and the second light guide layer 360 may be placed side by side.
  • the first light guide layer 310 is used to guide the light signal in the first direction returned by the finger to the pixels below it
  • the second light guide layer 360 is used to guide the light signal in the second direction returned by the finger to the pixels below it.
  • pixels are used to guide the light signal in the second direction returned by the finger to the pixels below it.
  • the device 300 further includes a filter layer.
  • the filter layer is arranged in the light path between the display screen and the image acquisition unit 320, and is used to filter light signals in non-target wavelength bands and transmit light signals in the target wavelength bands.
  • the transmittance of the filter layer to light in the target wavelength band is ⁇ 80%
  • the cut-off rate to light in the non-target wavelength band is ⁇ 80%
  • the filter layer may be an independently formed filter layer.
  • the filter layer may be a filter layer formed by using blue crystal or blue glass as a carrier.
  • the filter layer may be a coating formed on the surface of any layer in the optical path.
  • a film can be coated on the surface of the pixel, the surface of any layer of the transparent medium layer, or the lower surface of the microlens to form a filter layer.
  • the fingerprint detection device 300 may further include: a medium and a metal layer, which may include a connection circuit for pixels.
  • the medium and the metal layer can be arranged above the photosensitive pixel, this way is Front Side Illumination (FSI); the medium and the metal layer can also be arranged below the photosensitive pixel, this way is the back-illuminated type ( Back Side Illumination, BSI).
  • FSI Front Side Illumination
  • BSI Back Side Illumination
  • An embodiment of the present application also provides an electronic device, which includes the fingerprint detection device in the foregoing various embodiments of the present application.
  • the electronic device further includes a display screen, and the display screen may be a common non-folding display screen, and the display screen may also be a foldable display screen, or called a flexible display screen.
  • 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.

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Abstract

一种指纹检测的装置，能够提高指纹检测性能。所述装置适用于显示屏下方以实现屏下光学指纹检测，所述装置包括：第一导光层，设置在图像采集单元上方，用于将入射至所述显示屏上方的手指并经所述手指返回的倾斜光信号，传输至所述图像采集单元，其中，所述倾斜光信号包括来自所述手指的反射光信号和透射光信号，所述反射光信号经过位于所述手指至所述图像采集单元之间的光路中的线偏振单元后被衰减，使得到达所述图像采集单元的所述透射光信号的比例相对地增加；所述图像采集单元，所述图像采集单元中位于所述第一导光层下方的像素用于接收所述倾斜光信号，所述倾斜光信号用于获取所述手指的指纹图像。

Description

指纹检测的装置和电子设备 技术领域
本申请实施例涉及指纹检测领域，并且更具体地，涉及一种指纹检测的装置和电子设备。
背景技术
光学屏下指纹检测技术是通过采集光线在手指发生反射或透射形成的光信号，该光信号中携带手指的指纹信息，从而实现屏下指纹检测。对于特殊手指，例如较为干燥的手指，指纹与显示屏之间存在空气间隙，该空气间隙会导致指纹的脊和谷对光线的反射差异变小，使得指纹图像的对比度降低，影响了指纹检测性能。
发明内容
本申请实施例提供一种指纹检测的装置和电子设备，能够提高指纹检测性能。
第一方面，提供了一种指纹检测的装置，适用于显示屏下方以实现屏下光学指纹检测，所述装置包括：
第一导光层，设置在图像采集单元上方，用于将入射至所述显示屏上方的手指并经所述手指返回的倾斜光信号，传输至所述图像采集单元，其中，所述倾斜光信号包括来自所述手指的反射光信号和透射光信号，所述反射光信号经过位于所述手指至所述图像采集单元之间的光路中的线偏振单元后被衰减，使得到达所述图像采集单元的所述透射光信号的比例相对地增加；
所述图像采集单元，所述图像采集单元中位于所述第一导光层下方的像素用于接收所述倾斜光信号，所述倾斜光信号用于获取所述手指的指纹图像。
在一种可能的实现方式中，所述线偏振单元集成在所述显示屏内部，且位于所述显示屏的机发光二极管OLED层上方。
在一种可能的实现方式中，所述线偏振单元位于所述显示屏与所述图像采集单元之间。
在一种可能的实现方式中，所述线偏振单元的偏振方向垂直于所述倾斜光信号的入射面；或者，所述线偏振单元的偏振方向平行于所述倾斜光信号 的入射面；或者，所述线偏振单元的偏振方向与所述倾斜光信号的入射面之间的夹角为45°。
在一种可能的实现方式中，所述倾斜光信号的倾斜角度小于或等于布儒斯特角。
在一种可能的实现方式中，所述第一导光层包括：由多个微透镜形成的微透镜阵列，用于对所述倾斜光信号进行会聚；至少一个挡光层，设置在所述微透镜阵列下方，其中每个挡光层包括与所述多个微透镜分别对应的多个开孔，经每个微透镜会聚后的倾斜光信号穿过不同挡光层内与所述每个微透镜对应的开孔，到达所述图像采集单元。
在一种可能的实现方式中，所述微透镜阵列中每个微透镜的聚光面在与其光轴垂直的平面上的投影为矩形或者圆形。
在一种可能的实现方式中，所述微透镜阵列中每个微透镜的聚光面的各个方向上的曲率相同。
在一种可能的实现方式中，所述至少一个挡光层中的最后一个挡光层集成在所述图像采集单元中。
在一种可能的实现方式中，不同挡光层内与相同微透镜对应的开孔的孔径由上至下依次减小。
在一种可能的实现方式中，所述装置还包括：透明介质层，用于连接所述微透镜阵列、所述至少一个挡光层以及所述图像采集单元，并填充所述至少一个挡光层中的开孔。
在一种可能的实现方式中，所述第一导光层包括：光学功能膜层，用于在所述手指返回的各个方向的光信号中，选择所述倾斜光信号，并将所述倾斜光信号传输至所述图像采集单元。
在一种可能的实现方式中，所述光学功能膜层还用于：对所选择的所述倾斜光信号进行折射，以使所述倾斜光信号垂直入射至所述图像采集单元的像素上。
在一种可能的实现方式中，所述光学功能膜层为光栅膜或者棱镜膜。
在一种可能的实现方式中，所述光学功能膜层集成在于所述图像采集单元中，或者作为与所述图像采集单元相对独立的器件设置在所述图像采集单元上方。
在一种可能的实现方式中，所述第一导光层包括：由多个导光通道形成 的导光通道阵列。
在一种可能的实现方式中，所述多个导光通道由光纤、空气通孔、或者透光材料形成。
在一种可能的实现方式中，所述第一导光层水平设置，所述多个导光通道相对于所述第一导光层的表面倾斜，以将所述倾斜光信号引导至所述图像采集单元。
在一种可能的实现方式中，所述多个导光通道由光纤形成，所述第一导光层水平设置，所述多个导光通道垂直于所述第一导光层的表面，所述倾斜光信号在所述多个导光通道中的每个导光通道内经过至少一次全反射后到达所述图像采集单元。
在一种可能的实现方式中，所述多个导光通道垂直于所述第一导光层的表面，所述第一导光层倾斜设置，以将所述倾斜光信号引导至所述图像采集单元。
在一种可能的实现方式中，所述装置还包括：第二导光层，设置在所述图像采集单元上方，用于将所述手指返回的第二方向的光信号，传输至所述图像采集单元；其中，所述图像采集单元中位于所述第二导光层下方的像素用于接收所述第二方向的光信号，所述第二方向的光信号用于获取所述手指的指纹图像，其中，所述第一导光层传输的所述倾斜光信号为第一方向的光信号，所述第二方向与所述第一方向不同。
在一种可能的实现方式中，所述第二方向为垂直方向或者倾斜方向。
在一种可能的实现方式中，所述装置还包括：滤波层，设置在所述显示屏至所述图像采集单元之间的光路中，用于滤除非目标波段的光信号，透过目标波段的光信号。
在一种可能的实现方式中，所述滤波层为形成在所述光路中任一层表面的镀膜。
在一种可能的实现方式中，所述图像采集单元包括一个光学指纹传感器，或者包括拼接在一起的多个光学指纹传感器。
第二方面，提供了一种指纹检测的装置，适用于显示屏下方以实现屏下光学指纹检测，所述装置包括：
第一导光层，设置在图像采集单元上方，用于将入射至所述显示屏上方的手指并经所述手指返回的第一方向的光信号，传输至所述图像采集单元；
第二导光层，设置在所述图像采集单元上方，用于将所述手指返回的第二方向的光信号，传输至所述图像采集单元；
所述图像采集单元，所述图像采集单元中位于所述第一导光层下方的像素用于接收所述第一方向的光信号，所述图像采集单元中位于所述第二导光层下方的像素用于接收所述第二方向的光信号，所述第一方向的光信号和所述第二方向的光信号用于获取所述手指的指纹图像，所述第一方向与所述第二方向不同。
在一种可能的实现方式中，所述倾斜光信号包括来自所述手指的反射光信号和透射光信号，其中，所述反射光信号经过位于所述手指至所述图像采集单元之间的光路中的线偏振单元后被衰减，使得到达所述图像采集单元的所述透射光信号的比例相对地增加。
在一种可能的实现方式中，所述第一方向为倾斜方向，所述第二方向为垂直方向或者倾斜方向。
在一种可能的实现方式中，所述第一方向的光信号的入射面与所述线偏振单元的偏振方向垂直；或者，所述第一方向的光信号的入射面与所述线偏振单元的偏振方向平行；或者，所述第一方向的光信号的入射面与所述线偏振单元的偏振方向之间的夹角为45°。
在一种可能的实现方式中，所述线偏振单元集成在所述显示屏内部，且位于所述显示屏的OLED层上方。
在一种可能的实现方式中，所述线偏振单元位于所述显示屏与所述图像采集单元之间。
在一种可能的实现方式中，所述倾斜光信号的倾斜角度小于或等于布儒斯特角。
第三方面，提供了一种电子设备，包括：
显示屏；以及，
第一方面或第一方面的任意可能的实现方式中的指纹检测的装置，或者，第二方面或第二方面的任意可能的实现方式中的指纹检测的装置。
基于上述技术方案，采用倾斜光进行指纹检测，并采用线偏振单元，使得经过线偏振单元后的光线中的反射光能被衰减，从而相对地增加到达图像采集单元的该手指的透射光信号的比例，提升了指纹检测性能，尤其是对特殊手指例如干手指的检测性能。
附图说明
图1A和图2A是本申请可以适用的电子设备的结构示意图。
图1B和图2B分别是图1A和图2A所示的电子设备沿A-A’方向的剖面示意图。
图3是本申请实施例的指纹检测的装置的示意性框图。
图4是基于手指的反射光信号和透射光信号进行指纹检测的示意图。
图5A和图5B是手指与显示屏之间的距离与指纹图像的对比度之间的关系的示意图。
图6是本申请实施例的一种可能的线偏振单元的示意图。
图7是本申请实施例的一种可能的第一导光层的示意图。
图8是本申请实施例的一种可能的第一导光层的示意图。
图9是本申请实施例的一种可能的第一导光层的示意图。
图10A和图10B是本申请实施例的一种可能的第一导光层的示意图。
图11A、图11B和图11C是本申请实施例的一种可能的第一导光层的示意图。
图12是本申请另一实施例的指纹检测的装置的示意性框图。
图13A、图13B和图13C是根据不同方向光线进行指纹检测的示意图。
图14是本申请实施例的一种可能的第二导光层的示意图。
图15是本申请实施例的一种可能的第二导光层的示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
应理解，本申请实施例可以应用于指纹系统，包括但不限于光学、超声波或其他指纹检测系统和基于光学、超声波或其他指纹成像的医疗诊断产品，本申请实施例仅以光学指纹系统为例进行说明，但不应对本申请实施例构成任何限定，本申请实施例同样适用于其他采用光学、超声波或其他成像技术的系统等。
作为一种常见的应用场景，本申请实施例提供的光学指纹系统可以应用在智能手机、平板电脑以及其他具有显示屏的移动终端或者其他电子设备；更具体地，在上述电子设备中，光学指纹模组可以设置在显示屏下方的局部 区域或者全部区域，从而形成屏下(Under-display或Under-screen)光学指纹系统。或者，所述光学指纹模组也可以部分或者全部集成至所述电子设备的显示屏内部，从而形成屏内(In-display或In-screen)光学指纹系统。
光学屏下指纹检测技术使用从设备显示组件的顶面返回的光来进行指纹感应和其他感应操作。该返回的光携带与该顶面接触的物体(例如手指)的信息，通过采集和检测该返回的光，实现位于显示屏下方的特定光学传感器模块。光学传感器模块的设计可以为通过恰当地配置用于采集和检测返回的光的光学元件来实现期望的光学成像。
图1A和图2A示出了本申请实施例可以适用的电子设备的示意图。其中，图1A和图2A为电子设备10的定向示意图，图1B和图2B分别为图1A和图2A所示的电子设备10沿A-A’方向的部分剖面示意图。
所述电子设备10包括显示屏120和光学指纹模组130。其中，所述光学指纹模组130设置在所述显示屏120下方的局部区域。所述光学指纹模组130包括光学指纹传感器，所述光学指纹传感器包括具有多个光学感应单元131(也可以称为像素、感光像素、像素单元等)的感应阵列133。所述感应阵列133所在区域或者其感应区域为所述光学指纹模组130的指纹检测区域103(也称为指纹采集区域、指纹识别区域等)。如图1所示，所述指纹检测区域103位于所述显示屏120的显示区域之中。在一种替代实施例中，所述光学指纹模组130还可以设置在其他位置，比如所述显示屏120的侧面或者所述电子设备10的边缘非透光区域，并通过光路设计来将来自所述显示屏120的至少部分显示区域的光信号导引到所述光学指纹模组130，从而使得所述指纹检测区域103实际上位于所述显示屏120的显示区域。
应当理解，所述指纹检测区域103的面积可以与所述光学指纹模组130的感应阵列133的面积不同，例如通过例如透镜成像的光路设计、反射式折叠光路设计或者其他光线会聚或者反射等光路设计，可以使得所述光学指纹模组130的指纹检测区域103的面积大于所述光学指纹模组130的感应阵列133的面积。在其他替代实现方式中，如果采用例如光线准直方式进行光路引导，所述光学指纹模组130的指纹检测区域103也可以设计成与所述光学指纹模组130的感应阵列的面积基本一致。
因此，使用者在需要对所述电子设备10进行解锁或者其他指纹验证的时候，只需要将手指按压在位于所述显示屏120的指纹检测区域103，便可 以实现指纹输入。由于指纹检测可以在屏内实现，因此采用上述结构的电子设备10无需其正面专门预留空间来设置指纹按键(比如Home键)，从而可以采用全面屏方案，即所述显示屏120的显示区域可以基本扩展到整个电子设备10的正面。
作为一种可选的实现方式，如图1B所示，所述光学指纹模组130包括光检测部分134和光学组件132。所述光检测部分134包括所述感应阵列133以及与所述感应阵列133电性连接的读取电路及其他辅助电路，其可以在通过半导体工艺制作在一个芯片(Die)上，比如光学成像芯片或者光学指纹传感器。所述感应阵列133具体为光探测器(Photodetector)阵列，其包括多个呈阵列式分布的光探测器，所述光探测器可以作为如上所述的光学感应单元。所述光学组件132可以设置在所述光检测部分134的感应阵列133的上方，其可以具体包括滤光层(Filter)、导光层(也称光路引导结构)、以及其他光学元件，所述滤光层可以用于滤除穿透手指的环境光，而所述导光层主要用于从手指表面反射回来的反射光导引至所述感应阵列133进行光学检测。
在具体实现上，所述光学组件132可以与所述光检测部分134封装在同一个光学指纹部件。比如，所述光学组件132可以与所述光学检测部分134封装在同一个光学指纹芯片，也可以将所述光学组件132设置在所述光检测部分134所在的芯片外部，比如将所述光学组件132贴合在所述芯片上方，或者将所述光学组件132的部分元件集成在上述芯片之中。
其中，所述光学组件132的导光层有多种实现方案，比如，所述导光层可以具体为在半导体硅片制作而成的准直器(Collimator)层，其具有多个准直单元或者微孔阵列，所述准直单元可以具体为小孔，从手指反射回来的反射光中，垂直入射到所述准直单元的光线可以穿过并被其下方的光学感应单元接收，而入射角度过大的光线在所述准直单元内部经过多次反射被衰减掉，因此每一个光学感应单元基本只能接收到其正上方的指纹纹路反射回来的反射光，从而所述感应阵列133便可以检测出手指的指纹图像。
在另一种实现方式中，所述导光层也可以为光学透镜(Lens)层，其具有一个或多个透镜单元，比如一个或多个非球面透镜组成的透镜组，其用于将从手指反射回来的反射光会聚到其下方的光检测部分134的感应阵列133，以使得所述感应阵列133可以基于所述反射光进行成像，从而得到所述手指 的指纹图像。可选地，所述光学透镜层在所述透镜单元的光路中还可以形成有针孔，所述针孔可以配合所述光学透镜层扩大所述光学指纹模组130的视场，以提高所述光学指纹模组130的指纹成像效果。
在其他实现方式中，所述导光层也可以具体采用微透镜(Micro-Lens)层，所述微透镜层具有由多个微透镜形成的微透镜阵列，其可以通过半导体生长工艺或者其他工艺形成在所述光检测部分134的感应阵列133上方，并且每一个微透镜可以分别对应于所述感应阵列133的其中一个感应单元。并且，所述微透镜层和所述感应单元之间还可以形成其他光学膜层，比如介质层或者钝化层。更具体地，所述微透镜层和所述感应单元之间还可以包括具有微孔(或称为开孔)的挡光层(或称为遮光层、阻光层等)，其中所述微孔形成在其对应的微透镜和感应单元之间，所述挡光层可以阻挡相邻微透镜和感应单元之间的光学干扰，并使得所述感应单元所对应的光线通过所述微透镜会聚到所述微孔内部并经由所述微孔传输到所述感应单元以进行光学指纹成像。
应理解，上述导光层的几种实现方案可以单独使用也可以结合使用。比如，可以在所述准直器层或者所述光学透镜层的上方或下方进一步设置微透镜层。当然，在所述准直器层或者所述光学透镜层与所述微透镜层结合使用时，其具体叠层结构或者光路可能需要按照实际需要进行调整。
作为一种可选的实现方式，所述显示屏120可以采用具有自发光显示单元的显示屏，比如有机发光二极管(Organic Light-Emitting Diode，OLED)显示屏或者微型发光二极管(Micro-LED)显示屏。以采用OLED显示屏为例，所述光学指纹模组130可以利用所述OLED显示屏120位于所述指纹检测区域103的显示单元(即OLED光源)作为光学指纹检测的激励光源。当手指140按压在所述指纹检测区域103时，显示屏120向所述指纹检测区域103上方的目标手指140发出一束光111，该光111在手指140的表面发生反射形成反射光或者经过所述手指140内部散射而形成散射光。在相关专利申请中，为便于描述，上述反射光和散射光统称为反射光。由于指纹的脊(ridge)141与谷(valley)142对于光的反射能力不同，因此，来自指纹脊的反射光151和来自指纹谷的反射光152具有不同的光强，反射光经过光学组件132后，被光学指纹模组130中的感应阵列133所接收并转换为相应的电信号，即指纹检测信号；基于所述指纹检测信号便可以获得指纹图像数据， 并且可以进一步进行指纹匹配验证，从而在电子设备10实现光学指纹检测功能。
在其他实现方式中，所述光学指纹模组130也可以采用内置光源或者外置光源来提供用于进行指纹检测的光信号。在这种情况下，所述光学指纹模组130可以适用于非自发光显示屏，比如液晶显示屏或者其他的被动发光显示屏。以应用在具有背光模组和液晶面板的液晶显示屏为例，为支持液晶显示屏的屏下指纹检测，所述电子设备10的光学指纹系统还可以包括用于光学指纹检测的激励光源，所述激励光源可以具体为红外光源或者特定波长非可见光的光源，其可以设置在所述液晶显示屏的背光模组下方或者设置在所述电子设备10的保护盖板下方的边缘区域，而所述光学指纹模组130可以设置液晶面板或者保护盖板的边缘区域下方并通过光路引导以使得指纹检测光可以到达所述光学指纹模组130；或者，所述光学指纹模组130也可以设置在所述背光模组下方，且所述背光模组通过对扩散片、增亮片、反射片等膜层进行开孔或者其他光学设计以允许指纹检测光穿过液晶面板和背光模组并到达所述光学指纹模组130。当采用所述光学指纹模组130采用内置光源或者外置光源来提供用于进行指纹检测的光信号时，其检测原理与上面描述内容是一致的。
在具体实现上，所述电子设备10还可以包括透明保护盖板，所述盖板可以为玻璃盖板或者蓝宝石盖板，其位于所述显示屏120的上方并覆盖所述电子设备10的正面。因此，本申请实施例中，所谓的手指按压在所述显示屏120实际上是指按压在所述显示屏120上方的盖板或者覆盖所述盖板的保护层表面。
所述电子设备10还可以包括电路板150，电路板150设置在所述光学指纹模组130的下方。光学指纹模组130可以通过背胶粘接在电路板150上，并通过焊盘及金属线焊接与电路板150实现电性连接。光学指纹模组130可以通过电路板150实现与其他外围电路或者电子设备10的其他元件的电性互连和信号传输。比如，光学指纹模组130可以通过电路板150接收电子设备10的处理单元的控制信号，并且还可以通过电路板150将来自光学指纹模组130的指纹检测信号输出给电子设备10的处理单元或者控制单元等。
在某些实现方式中，所述光学指纹模组130可以仅包括一个光学指纹传感器，此时光学指纹模组130的指纹检测区域103的面积较小且位置固定， 因此用户在进行指纹输入时需要将手指按压到所述指纹检测区域103的特定位置，否则光学指纹模组130可能无法采集到指纹图像而造成用户体验不佳。在其他替代实施例中，所述光学指纹模组130可以具体包括多个光学指纹传感器。所述多个光学指纹传感器可以通过拼接方式并排设置在所述显示屏120的下方，且所述多个光学指纹传感器的感应区域共同构成所述光学指纹模组130的指纹检测区域103。从而所述光学指纹模组130的指纹检测区域103可以扩展到所述显示屏的下半部分的主要区域，即扩展到手指惯常按压区域，从而实现盲按式指纹输入操作。进一步地，当所述光学指纹传感器数量足够时，所述指纹检测区域103还可以扩展到半个显示区域甚至整个显示区域，从而实现半屏或者全屏指纹检测。
例如图2A和图2B所示的电子设备10，所述电子设备10中的光学指纹装置130包括多个光学指纹传感器时，所述多个光学指纹传感器可以通过例如拼接等方式并排设置在所述显示屏120的下方，且所述多个光学指纹传感器的感应区域共同构成所述光学指纹装置130的指纹检测区域103。
可选地，与所述光学指纹装置130的多个光学指纹传感器相对应，所述光学组件132中可以有多个导光层，每个导光层分别对应一个光学指纹传感器，并分别贴合设置在其对应的光学指纹传感器的上方。或者，所述多个光学指纹传感器也可以共享一个整体的导光层，即所述导光层具有一个足够大的面积以覆盖所述多个光学指纹传感器的感应阵列。另外，所述光学组件132还可以包括其他光学元件，比如滤光层(Filter)或其他光学膜片，其可以设置在所述导光层和所述光学指纹传感器之间或者设置在所述显示屏120与所述导光层之间，主要用于隔离外界干扰光对光学指纹检测的影响。其中，所述滤光片可以用于滤除穿透手指并经过所述显示屏120进入所述光学指纹传感器的环境光，与所述导光层相类似，所述滤光片可以针对每个光学指纹传感器分别设置以滤除干扰光，或者也可以采用一个大面积的滤光片同时覆盖所述多个光学指纹传感器。
所述导光层也可以采用光学镜头(Lens)，所述光学镜头上方可以通过遮光材料形成小孔配合所述光学镜头将指纹检测光会聚到下方的光学指纹传感器以实现指纹成像。相类似地，每一个光学指纹传感器可以分别配置一个光学镜头以进行指纹成像，或者，所述多个光学指纹传感器也可以利用同一个光学镜头来实现光线会聚和指纹成像。在其他替代实施例中，每一个光 学指纹传感器甚至还可以具有两个感应阵列(Dual Array)或者多个感应阵列(Multi-Array)，且同时配置两个或多个光学镜头配合所述两个或多个感应阵列进行光学成像，从而减小成像距离并增强成像效果。
以上所示的指纹传感器的数量、尺寸和排布情况仅为示例，可以根据实际需求进行调整。例如，该多个指纹传感器的个数可以为2个、3个、4个或5个等，该多个指纹传感器可以呈方形或圆形分布等。
本申请实施例可以应用于各类手指的检测，尤其能够适用于干手指的检测。所谓的干手指，指的是比较干燥的手指或者较为干净的手指。目前采用垂直光线进行指纹检测的方案对干手指的指纹检测效果欠佳，而本申请实施例提供的指纹检测的方案能够提升对干手指的指纹检测性能。
本申请实施例的指纹检测的装置适用于显示屏下方以实现屏下光学指纹检测。图3示出了本申请实施例的指纹检测的装置300的示意图。该装置300包括第一导光层310和图像采集单元320。图像采集单元320可以参见上述光检测部分134的相关描述，本实施例不进行赘述。
所述第一导光层310设置在所述图像采集单元320的上方。所述第一导光层310用于将入射至显示屏上方的手指并经该手指返回的倾斜光信号，传输至图像采集单元320。
所述手指返回的光信号中包括来自该手指的反射光信号和透射光信号。其中，所述反射光信号经过线偏振单元330后被衰减，从而使得到达所述图像采集单元320的所述透射光信号的比例相对地增加。
所述线偏振单元330位于所述手指至所述图像采集单元320之间的光路中设置有。所述线偏振单元330用于衰减所述反射光信号，从而相对地增加到达图像采集单元320的透射光信号的比例。
所述线偏振单元330可以集成在所述显示屏内部，从而作为显示屏的一部分，例如位于所述显示屏的OLED层上方；或者，所述线偏振单元330位于所述第一导光层310与所述图像采集单元320之间；或者，所述线偏振单元330集成在所述图像采集单元320中，从而作为所述图像采集单元320的一部分，例如位于所述图像采集单元320的像素阵列的上方。
所述图像采集单元320包括一个光学指纹传感器，或者包括多个拼接在一起的多个光学指纹传感器，例如图2A和图2B所示。其中每个光学指纹传感器包括由多个像素形成的像素阵列。图像采集单元320中位于第一导光 层310下方的像素用于接收所述倾斜光信号，所述倾斜光信号用于获取该手指的指纹图像。
下面结合图4、图5A、图5B对本申请实施例的检测原理进行详细说明。
在进行指纹检测时，入射至显示屏340上方的手指并经该手指返回的光信号中包括两部分，一部分是来自该手指的反射光信号，另一部分是来自该手指的透射光信号。例如图4所示，采用左侧所示的所述反射光信号获取的指纹图像表现为谷亮脊暗(正色指纹)。并且随着手指与显示屏之间的接触越好，脊处越暗，脊和谷之间的对比度越好。采用右侧所示的所述透射光信号获取的指纹图像表现为谷暗脊亮(反色指纹)，这是由于指纹的脊内存在血液和组织，光线会在脊内发生散射并从脊中出射，而入射至指纹的谷的光线在谷处发生多次反射后迅速衰弱，导致从谷处出射的光线十分微弱，因此表现为谷暗脊亮。由于反射光成像和透射光成像得到的指纹图像呈现相反的状态，当反射光和透射光同时存在时，正色指纹和反色指纹相互抵消，容易使指纹图像变得模糊。
图5A和图5B示出了手指与显示屏之间的距离与指纹图像的对比度之间的关系，其中，图5A所示为采用垂直光信号进行指纹检测，图5B所示为采用倾斜光进行指纹检测。横坐标为手指与显示屏之间的距离，纵坐标为指纹图像的对比度。当指纹与显示屏接触较好，此时主要是反射光成像占主导，指纹图像呈现谷亮脊暗的特征，此时对正常手指的指纹检测性能较佳。当指纹与显示屏之间的接触逐渐变差，随着脊与显示屏之间的距离变大，反射光成像的效果逐渐减弱，透射光成像逐渐占主导，指纹图像呈现谷暗脊亮的特征。当反射光成像与透射光成像处于势均力敌的状态时，指纹图像的对比度最低，将这个阶段称为过渡带。在该过渡带内，由于反射光成像和透射光成像的指纹图像相互抵消，使得最终得到的手指的指纹图像的对比度较差。
反射光成像对手指与显示屏之间的距离变化更加敏感，而透射光成像对该距离的变化不太敏感。因此，在对干手指进行检测时，期望透射光成像占主导，提升透射光的比重，以减小该过渡带，从而提升指纹检测性能。
本申请实施例中采用倾斜光进行指纹检测，并通过线偏振单元对手指的反射光信号进行衰减，以相对地增加到达图像采集单元的透射光信号的比例，从而提升指纹检测性能，尤其是对特殊手指例如干手指的识别性能。
从图5A和图5B中可以看出，相对于采用垂直光信号进行指纹检测， 采用倾斜光信号进行指纹检测时该过渡带明显减小，因此提高了对干手指的检测性能。
线偏振单元330的偏振方向与所述倾斜光信号的入射面之间的夹角位于0°至90°之间。例如，线偏振单元330的偏振方向垂直于所述倾斜光信号的入射面、平行于所述倾斜光信号的入射面、或者与所述倾斜光信号的入射面之间的夹角为45°。
图6示出了本申请实施例的一种可能的线偏振单元330。假设线偏振单元330位于显示屏340中的OLED层341上方。OLED层341发出的光线经过该线偏振单元330后变成线偏振光照射至盖板342上方的手指350。经手指350透射后，该透射光线的偏振方向不变，从而能够通过该线偏振单元330后返回，并经过导光层310的引导后传输至图像采集单元320。
而对于经手指350反射的光线，由于是倾斜入射至手指350，因此手指350的反射光线中包括p波和s波，其中，p波的偏振方向与光线的入射平面平行，s波的偏振方向与入射平面垂直，该入射平面垂直于显示屏340。
如果线偏振单元330的偏振极性与倾斜光的入射平面(或者称为所述倾斜光信号的接收平面)平行，则手指的反射光线中的s波会被衰减，而只剩p波能够通过该线偏振单元330后返回，并经过导光层310的引导后传输至图像采集单元320。如果线偏振单元330的偏振极性与入射平面垂直，则手指的反射光线中的p波会被衰减，而只剩s波能够通过该线偏振单元330后返回，并经过导光层310的引导后传输至图像采集单元320，例如图6所示。无论是衰减掉p波还是s波，手指的反射光信号均被减弱，而手指的透射光信号不变，因此相对而言，手指返回的光信号中透射光信号的比例增加了，减小了过渡带，提高了干手指的检测性能。
通常，反射光中的p波通常少于s波，如果入射角达到布儒斯特角，则反射光中没有p波，只剩s波，因而反射光是完全偏振的，其偏振方向垂直于入射平面。当入射角超过布儒斯特角后，s波和p波均增加，直至达到全反射角后被全部反射。因此，优选地，如果手指返回的倾斜光信号的倾斜角度小于或等于布儒斯特角，则能够使得手指返回的反射光信号尽可能少。
本申请实施例提供了第一导光层310的三种可能的实现方式。以下结合图7至图12进行详细描述。
方式1
所述第一导光层310包括由多个微透镜311形成的微透镜阵列，以及设置在微透镜阵列下方至少一个挡光层312。
其中，每个微透镜311用于对手指返回的倾斜光信号进行会聚。至少一个挡光层312中的每个挡光层312包括与多个微透镜311分别对应的多个开孔313，经每个微透镜311会聚后的所述倾斜光信号穿过不同挡光层312内与该微透镜311对应的开孔313，到达图像采集单元320。
微透镜311的聚光面在与其光轴垂直的平面上的投影可以为矩形或者圆形。微透镜311的聚光面是用于对光线起会聚作用的面。该聚光面可以是球面也可以是非球面。优选地，该聚光面在各个方向上的曲率相同，这样可以使微透镜311的各个方向的成像焦点在同一位置，从而保证成像质量。
每个微透镜311对应于图像采集单元320中的一个像素321，其中，经微透镜311会聚后的倾斜光信号穿过不同挡光层内与该微透镜311对应的开孔，到达与该微透镜311对应的像素321。
由于采用挡光层内的开孔对光线进行引导，因此，为了使倾斜光信号到达图像采集单元，不同挡光层内与所述每个微透镜对应的开孔的连线应为倾斜的，其倾斜角度等于或近似等于该倾斜光信号的倾斜角度。
应理解，本申请实施例不考虑各个层之间的折射对光线传输的影响。
所述挡光层312可以设置一层或多层。
例如图7所示，采用一个挡光层312时，该挡光层312可以集成在图像采集单元320中，比如采用金属掩膜(mask)的方式，在像素阵列上方形成一层挡光层。
例如图8和图9所示，采用多个挡光层312时，不同挡光层内与每个微透镜对应的开孔的连线的倾斜角度，等于手指返回的该倾斜光信号的倾斜角度。对于每个像素，多个挡光层中与该像素对应的开孔由上至下依次偏移设置，从而能够使像素321接收到手指返回的倾斜光信号，而阻挡其他方向的光信号。
可选地，多个挡光层中的最后一个挡光层可以集成在图像采集单元320中，例如图8和图9所示，当图像采集单元320中集成有一挡光层时，该挡光层具有更高的可靠性。
可选地，不同挡光层内与相同微透镜对应的开孔的孔径由上至下依次减小。例如图8和图9所示，上方的挡光层中的开孔孔径设置为大于下方的挡 光层中的开孔孔径，这样可以引导较多(一定的角度范围)的光信号至相应的像素。
可选地，在微透镜阵列、至少一个挡光层以及图像采集单元之间还设置有透明介质层。
其中，透明介质层用于连接所述微透镜阵列、所述至少一层挡光层以及所述图像采集单元中的像素，并填充所述至少一个挡光层中的开孔。
透明介质层可透过目标波段的光信号(即指纹检测所需波段的光信号)。例如，透明介质层可采用氧化物或氮化物等。
可选地，透明介质层可以包括多层，以分别实现保护、过渡和缓冲等功能。
例如，在无机层和有机层之间可以设置过渡层，以实现紧密的连接；在易氧化的层上可以设置保护层，以实现保护。
方式2
所述第一导光层310包括光学功能膜层314，用于在所述手指返回的各个方向的光信号中，选择所述倾斜光信号，并将所述倾斜光信号传输至所述图像采集单元320。
光学功能膜层314例如可以为光栅膜或者棱镜膜。
例如图10A所示，光学功能膜层314可以透过特定角度的倾斜光线316，并将该光线316传输至图像采集单元320，而阻挡其他角度的光线。
进一步地，可选地，光学功能膜层314还可以用于对所述倾斜光信号进行折射，以使所述倾斜光信号能够垂直入射至图像采集单元320的像素上。
例如图10B所示，光学功能膜层314可以透过特定角度的倾斜光线316，并对该光线316进行折射，使其垂直入射至图像采集单元320。由于图像采集单元320的像素对垂直接收到的光线的量子效率最高，因此这样可以获得最优的光电转换效率，进一步提高指纹检测性能。
可选地，光学功能膜层314可以集成在于图像采集单元320中，或者作为与图像采集单元320相对独立的器件设置在图像采集单元320上方。
方式3
所述第一导光层310包括由多个导光通道315形成的导光通道阵列。
所述导光通道315例如可以由光纤、空气通孔、或者透光材料形成。
在一种实现方式中，所述第一导光层310水平设置，所述多个导光通道 315相对于第一导光层310的表面倾斜，以将所述倾斜光信号引导至所述图像采集单元320。
例如图11A所示，第一导光层310平行于显示屏340设置，导光通道315为倾斜通道，其倾斜角度与手指返回的所述倾斜光信号的倾斜角度相同，从而使得所述倾斜光信号能够经过导光通道315到达图像采集单元320，而其他方向的光信号被阻挡。
在另一种实现方式中，所述多个导光通道315垂直于所述第一导光层310的表面，所述第一导光层310倾斜设置，以将所述倾斜光信号引导至所述图像采集单元320。
例如图11B所示，导光通道315为垂直通道，其垂直于第一导光层310的表面，此时，可以将第一导光层310倾斜设置，使其倾斜角度与手指返回的所述倾斜光信号的倾斜角度相同，从而使得所述倾斜光信号能够经过导光通道315到达图像采集单元320，而其他方向的光信号被阻挡。
在另一种实现方式中，所述第一导光层310水平设置，所述多个导光通道315垂直于所述第一导光层310的表面，所述倾斜光信号在所述多个导光通道315中的每个导光通道315内经过至少一次全反射后到达所述图像采集单元320。
例如图11C所示，第一导光层310平行于显示屏340设置，且导光通道315为垂直通道，所述导光通道315为光纤。由于光纤能够对特定角度的入射光线进行传输，因此，可以通过光纤实现对手指反射的特定角度的倾斜光信号的引导。所述倾斜光信号从光纤315的一端进入后，在光纤315中发生多次全反射，最终从光纤315的另一端出射，从而到达所述图像采集单元320。
本申请实施例还提供指纹检测的装置300的另一种实现方式。如图12所示，所述指纹检测的装置300包括第一导光层320、第二导光层360和图像采集单元320。
其中，所述第二导光层360设置在所述图像采集单元320上方，用于将所述手指返回的第二方向的光信号，传输至图像采集单元320。
图像采集单元320中位于第二导光层360下方的像素用于接收所述第二方向的光信号，所述第二方向的光信号用于获取所述手指的指纹图像。其中，所述第一导光层传输的所述倾斜光信号为第一方向的光信号，所述第二方向与所述第一方向不同。
该实施例中，指纹检测的装置300除了包括前述的所述第一导光层320，还可以包括第二导光层360。所述第一导光层320用于将入射至显示屏上方的手指并经所述手指返回的第一方向的光信号，传输至所述图像采集单元320；而所述第二导光层360用于将所述手指返回的第二方向的光信号，传输至图像采集单元320。由于可以同时检测不同方向的光信号从而进行指纹检测，因此提高了指纹检测性能。
所述第一方向与所述第二方向不同，若所述第一方向为倾斜方向，则所述第二方向可以为倾斜方向或者垂直方向。其中，所述第一方向和所述第二方向均为倾斜方向时，所述第二方向的光线的倾斜角度与所述第一方向的光线的倾斜角度可以相同或者不同。
其中，该实施例中，所述第一方向的光信号的入射面可以与所述线偏振单元330的偏振方向垂直；或者，所述第一方向的光信号的入射面与所述线偏振单元330的偏振方向平行；或者，所述第一方向的光信号的入射面与所述线偏振单元330的偏振方向成一定角度例如45°，本申请对此不做限定。
例如，如图13A所示，第一方向为倾斜方向，其与显示屏之间存在角度，其中图13A为俯视图，所示的箭头可以认为是第一方向的光线的入射面的在显示屏内的投影，其中虚线表示线偏振单元330的偏振方向。第二方向为垂直方向，其垂直于显示屏。在指纹检测区域103内，手指返回的第一方向的倾斜光信号通过第一导光层310传输至图像采集单元320，所述手指返回的垂直光信号通过第二导光层360传输至图像采集单元320。
又例如，如图13B所示，第一方向和第二方向均为倾斜方向，但是第一方向的光信号的入射面垂直于线偏振单元330的偏振方向，而第二方向的光信号的入射平面平行于线偏振单元330的偏振方向。其中图13B为俯视图，所示的箭头可以认为是第一方向和第二方向的光线的入射面的在显示屏内的投影，其中虚线表示线偏振单元330的偏振方向。
又例如，第一方向的光信号的入射面垂直于线偏振单元330的偏振方向，而第二方向的光信号与线偏振单元330的偏振方向之间夹角为45°。
可选地，装置300还可以包括更多的导光层，这些导光层分别用于将不同方向的光信号传输至图像采集单元320。例如图13C所示，可以在通过设置四个导光层，分别将来自A、B、C、D四个不同方向的光线引导至图像采集单元320。
该实施例中，通过采用不同导光层，传输不同方向的光信号至图像采集单元，以用于指纹检测，提高了指纹检测性能。
例如，采用倾斜光进行对干手指进行指纹检测时，主要关注的是脊-谷差值的大小，差值越大对比度越高，越容易找到特征点，进而进行指纹检测。对于干手指而言，采用倾斜光检测指纹时得到的指纹图像的对比度优于采用垂直光检测指纹时的对比度。但是对于正常手指而言，采用垂直光检测指纹时得到的指纹图像的对比度优于采用倾斜光检测指纹时的对比度。
该实施例中，在进行指纹检测时，若第一导光层310和第二导光层360分别用于传输倾斜光信号和垂直光信号，则手指的一部分指纹信息可以通过第一导光层320传输至图像采集单元320，第一导光层320将携带这部分指纹信息的倾斜光信号传输至相应的像素，从而能够在手指为干手指时，获取较优的指纹图像；而手指的另一部分指纹信息可以通过第二导光层360传输至图像采集单元320，第二导光层360将携带这部分指纹信息的垂直光信号传输至相应的像素，从而能够在手指为正常手指时，获取较优的指纹图像。这样，无论该手指为干手指还是正常手指，均能够获得较优的指纹图像，兼顾了正常手指和干手指的指纹检测性能，提高了指纹检测的成功率，提升用户体验。
本申请实施例中，所述第二导光层360也可以通过上述的方式1、方式2或者方式3来实现。
例如，采用方式1时，第二导光层360包括微透镜阵列和至少一个挡光层，以实现对垂直光线的引导。可以通过设置至少一个挡光层中开孔位置的偏移，实现对某一方向的光线的引导。例如图14所示，当第二导光层360用于引导垂直光信号时，每个挡光层362包括与多个微透镜分别对应的多个开孔363，不同挡光层362内对应于同一微透镜的开孔由上至下垂直布置，这样，经每个微透镜361会聚后的倾斜光信号穿过不同挡光层内与该微透镜361对应的开孔，垂直地到达图像采集单元320。也即，不同挡光层内与该微透镜361对应的开孔的连线垂直于显示屏，以使手指返回的垂直光信号能够到达图像采集单元320的像素321，而倾斜光线被阻挡。
又例如，采用方式2时，第二导光层360包括光学功能膜层317，以实现对垂直光线的筛选。例如图15所示，光学功能膜层317可以透过垂直光线318，并将该光线318传输至图像采集单元320，而阻挡倾斜光线。
又例如，采用方式3时，通过导光通道阵列实现对垂直光线的引导。第二导光层360平行于显示屏设置，且每个导光通道垂直于第二导光层360的表面，从而使手指返回的垂直光信号能够通过，而倾斜光线被阻挡。
第二导光层360中的其他特征可以参考前述对第一导光层310的相关描述，为了简洁，这里不在赘述。
本申请实施例对第一导光层310和第二导光层360的相对位置不做限定。例如图13A至图13C所示，第一导光层310和第二导光层360可以并排放置。其中，第一导光层310用于将手指返回的第一方向的光信号引导至其下方的像素，而第二导光层360用于将手指返回的第二方向的光信号引导至其下方的像素。
可选地，所述装置300还包括滤波层。其中，所述滤波层设置在所述显示屏至所述图像采集单元320之间的光路中，用于滤除非目标波段的光信号，透过目标波段的光信号。
可选地，所述滤波层对目标波段的光的透过率≥80％，对非目标波段的光的截止率≥80％。
可选地，所述滤波层可以为独立形成的滤波层。例如，所述滤波层可以是采用蓝水晶或者蓝玻璃做载体形成的滤波层。
可选地，所述滤波层可以为形成在所述光路中任一层表面的镀膜。例如，可以在像素表面、透明介质层中任一层的表面或微透镜的下表面等镀膜，形成滤波层。
可选地，所述指纹检测的装置300还可以包括：介质和金属层，其中可包括像素的连接电路。
例如，介质和金属层可以设置于感光像素的上方，这种方式为前照式(Front Side Illumination，FSI)；介质和金属层也可以设置于感光像素的下方，这种方式为背照式(Back Side Illumination，BSI)。
本申请实施例还提供了一种电子设备，该电子设备包括上述本申请各种实施例中的指纹检测的装置。
可选地，该电子设备还包括显示屏，该显示屏可以为普通的非折叠显示屏，该显示屏也可以为可折叠显示屏，或称为柔性显示屏。
作为示例而非限定，本申请实施例中的电子设备可以为终端设备、手机、平板电脑、笔记本电脑、台式机电脑、游戏设备、车载电子设备或穿戴式智 能设备等便携式或移动计算设备，以及电子数据库、汽车、银行自动柜员机(Automated Teller Machine，ATM)等其他电子设备。该穿戴式智能设备包括功能全、尺寸大、可不依赖智能手机实现完整或部分的功能，例如：智能手表或智能眼镜等，以及只专注于某一类应用功能，需要和其它设备如智能手机配合使用，如各类进行体征监测的智能手环、智能首饰等设备。
需要说明的是，在不冲突的前提下，本申请描述的各个实施例和/或各个实施例中的技术特征可以任意的相互组合，组合之后得到的技术方案也应落入本申请的保护范围。
应理解，本申请实施例中的具体的例子只是为了帮助本领域技术人员更好地理解本申请实施例，而非限制本申请实施例的范围，本领域技术人员可以在上述实施例的基础上进行各种改进和变形，而这些改进或者变形均落在本申请的保护范围内。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (33)

  1. 一种指纹检测的装置，其特征在于，适用于显示屏下方以实现屏下光学指纹检测，所述装置包括：
    第一导光层，设置在图像采集单元上方，用于将入射至所述显示屏上方的手指并经所述手指返回的倾斜光信号，传输至所述图像采集单元，其中，所述倾斜光信号包括来自所述手指的反射光信号和透射光信号，所述反射光信号经过位于所述手指至所述图像采集单元之间的光路中的线偏振单元后被衰减，使得到达所述图像采集单元的所述透射光信号的比例相对地增加；
    所述图像采集单元，所述图像采集单元中位于所述第一导光层下方的像素用于接收所述倾斜光信号，所述倾斜光信号用于获取所述手指的指纹图像。
  2. 根据权利要求1所述的装置，其特征在于，所述线偏振单元集成在所述显示屏内部，且位于所述显示屏的有机发光二极管OLED层上方。
  3. 根据权利要求1所述的装置，其特征在于，所述线偏振单元位于所述显示屏与所述图像采集单元之间。
  4. 根据权利要求1至3中任一项所述的装置，其特征在于，
    所述线偏振单元的偏振方向垂直于所述倾斜光信号的入射面；或者，
    所述线偏振单元的偏振方向平行于所述倾斜光信号的入射面；或者，
    所述线偏振单元的偏振方向与所述倾斜光信号的入射面之间的夹角为45°。
  5. 根据权利要求1至4中任一项所述的装置，其特征在于，所述倾斜光信号的倾斜角度小于或等于布儒斯特角。
  6. 根据权利要求1至5中任一项所述的装置，其特征在于，所述第一导光层包括：
    由多个微透镜形成的微透镜阵列，用于对所述倾斜光信号进行会聚；
    至少一个挡光层，设置在所述微透镜阵列下方，其中每个挡光层包括与所述多个微透镜分别对应的多个开孔，经每个微透镜会聚后的倾斜光信号穿过不同挡光层内与所述每个微透镜对应的开孔，到达所述图像采集单元。
  7. 根据权利要求6所述的装置，其特征在于，所述微透镜阵列中每个微透镜的聚光面在与其光轴垂直的平面上的投影为矩形或者圆形。
  8. 根据权利要求6或7所述的装置，其特征在于，所述微透镜阵列中每个微透镜的聚光面的各个方向上的曲率相同。
  9. 根据权利要求6至8中任一项所述的装置，其特征在于，所述至少一个挡光层中的最后一个挡光层集成在所述图像采集单元中。
  10. 根据权利要求6至9中任一项所述的装置，其特征在于，不同挡光层内与相同微透镜对应的开孔的孔径由上至下依次减小。
  11. 根据权利要求6至10中任一项所述的装置，其特征在于，所述装置还包括：
    透明介质层，用于连接所述微透镜阵列、所述至少一个挡光层以及所述图像采集单元，并填充所述至少一个挡光层中的开孔。
  12. 根据权利要求1至5中任一项所述的装置，其特征在于，所述第一导光层包括：
    光学功能膜层，用于在所述手指返回的各个方向的光信号中，选择所述倾斜光信号，并将所述倾斜光信号传输至所述图像采集单元。
  13. 根据权利要求12所述的装置，其特征在于，所述光学功能膜层还用于：
    对所选择的所述倾斜光信号进行折射，以使所述倾斜光信号垂直入射至所述图像采集单元的像素上。
  14. 根据权利要求12或13所述的装置，其特征在于，所述光学功能膜层为光栅膜或者棱镜膜。
  15. 根据权利要求12至14中任一项所述的装置，其特征在于，所述光学功能膜层集成在于所述图像采集单元中，或者作为与所述图像采集单元相对独立的器件设置在所述图像采集单元上方。
  16. 根据权利要求1至5中任一项所述的装置，其特征在于，所述第一导光层包括：
    由多个导光通道形成的导光通道阵列。
  17. 根据权利要求16所述的装置，其特征在于，所述多个导光通道由光纤、空气通孔、或者透光材料形成。
  18. 根据权利要求16或17所述的装置，其特征在于，所述第一导光层水平设置，所述多个导光通道相对于所述第一导光层的表面倾斜，以将所述倾斜光信号引导至所述图像采集单元。
  19. 根据权利要求16或17所述的装置，其特征在于，所述多个导光通道由光纤形成，所述第一导光层水平设置，所述多个导光通道垂直于所述第 一导光层的表面，所述倾斜光信号在所述多个导光通道中的每个导光通道内经过至少一次全反射后到达所述图像采集单元。
  20. 根据权利要求16或17所述的装置，其特征在于，所述多个导光通道垂直于所述第一导光层的表面，所述第一导光层倾斜设置，以将所述倾斜光信号引导至所述图像采集单元。
  21. 根据权利要求1至20中任一项所述的装置，其特征在于，所述装置还包括：
    第二导光层，设置在所述图像采集单元上方，用于将所述手指返回的第二方向的光信号，传输至所述图像采集单元，其中，所述第一导光层传输的所述倾斜光信号为第一方向的光信号，所述第二方向与所述第一方向不同；
    其中，所述图像采集单元中位于所述第二导光层下方的像素用于接收所述第二方向的光信号，所述第二方向的光信号用于获取所述手指的指纹图像。
  22. 根据权利要求21所述的装置，其特征在于，所述第二方向为垂直方向或者倾斜方向。
  23. 根据权利要求1至22中任一项所述的装置，其特征在于，所述装置还包括：
    滤波层，设置在所述显示屏至所述图像采集单元之间的光路中，用于滤除非目标波段的光信号，透过目标波段的光信号。
  24. 根据权利要求23所述的装置，其特征在于，所述滤波层为形成在所述光路中任一层表面的镀膜。
  25. 根据权利要求1至24中任一项所述的装置，其特征在于，所述图像采集单元包括一个光学指纹传感器，或者包括拼接在一起的多个光学指纹传感器。
  26. 一种指纹检测的装置，其特征在于，适用于显示屏下方以实现屏下光学指纹检测，所述装置包括：
    第一导光层，设置在图像采集单元上方，用于将入射至所述显示屏上方的手指并经所述手指返回的第一方向的光信号，传输至所述图像采集单元；
    第二导光层，设置在所述图像采集单元上方，用于将所述手指返回的第二方向的光信号，传输至所述图像采集单元；
    所述图像采集单元，所述图像采集单元中位于所述第一导光层下方的像素用于接收所述第一方向的光信号，所述图像采集单元中位于所述第二导光 层下方的像素用于接收所述第二方向的光信号，所述第一方向的光信号和所述第二方向的光信号用于获取所述手指的指纹图像，所述第一方向与所述第二方向不同。
  27. 根据权利要求26所述的装置，其特征在于，所述光信号包括来自所述手指的反射光信号和透射光信号，其中，所述反射光信号经过位于所述手指至所述图像采集单元之间的光路中的线偏振单元后被衰减，使得到达所述图像采集单元的所述透射光信号的比例相对地增加。
  28. 根据权利要求26或27所述的装置，其特征在于，所述第一方向为倾斜方向，所述第二方向为垂直方向或者倾斜方向。
  29. 根据权利要求28所述的装置，其特征在于，所述线偏振单元集成在所述显示屏内部，且位于所述显示屏的有机发光二极管OLED层上方。
  30. 根据权利要求28所述的装置，其特征在于，所述线偏振单元位于所述显示屏与所述图像采集单元之间。
  31. 根据权利要求26至30中任一项所述的装置，其特征在于，
    所述第一方向的光信号的入射面与所述线偏振单元的偏振方向垂直；或者，
    所述第一方向的光信号的入射面与所述线偏振单元的偏振方向平行；或者，
    所述第一方向的光信号的入射面与所述线偏振单元的偏振方向之间的夹角为45°。
  32. 根据权利要求26至31中任一项所述的装置，其特征在于，所述倾斜光信号的倾斜角度小于或等于布儒斯特角。
  33. 一种电子设备，其特征在于，包括：
    显示屏；以及，
    根据权利要求1至32中任一项所述的装置，所述装置设置于所述显示屏下方，以实现屏下光学指纹检测。
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