WO2021249123A1 - 显示装置及其指纹识别方法 - Google Patents

显示装置及其指纹识别方法 Download PDF

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Publication number
WO2021249123A1
WO2021249123A1 PCT/CN2021/094131 CN2021094131W WO2021249123A1 WO 2021249123 A1 WO2021249123 A1 WO 2021249123A1 CN 2021094131 W CN2021094131 W CN 2021094131W WO 2021249123 A1 WO2021249123 A1 WO 2021249123A1
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WIPO (PCT)
Prior art keywords
light
backlight module
layer
liquid crystal
fingerprint identification
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PCT/CN2021/094131
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English (en)
French (fr)
Inventor
海晓泉
丁小梁
梁轩
丁丁
王迎姿
Original Assignee
京东方科技集团股份有限公司
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Publication of WO2021249123A1 publication Critical patent/WO2021249123A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • 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
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Definitions

  • the present disclosure relates to the field of display technology, in particular to a display device and a fingerprint identification method thereof.
  • Fingerprint recognition as a biometric method, provides a huge role in protecting personal privacy.
  • almost all electronic products on the market are equipped with fingerprint recognition systems.
  • fingerprint recognition systems For example, cars, mobile phones, and card punches can all have fingerprint recognition functions.
  • the embodiment of the present disclosure provides a fingerprint identification method for a display device, including:
  • At least one light-emitting area corresponding to the touched position is determined in the backlight module of the display device, and a deflection area corresponding to the light-emitting area is determined in the liquid crystal layer; the liquid crystal The layer is located on the light emitting side of the backlight module;
  • the backlight module is controlled to emit light only in the light-emitting area, and the liquid crystal molecules in the deflection area in the liquid crystal layer are controlled to deflect, so that the light emitted by the backlight module in the light-emitting area is first polarized Layer, the liquid crystal layer and the second polarizing layer, a point light source is formed on the light exit surface of the second polarizing layer; the first polarizing layer is located between the backlight module and the liquid crystal layer, and the first polarizing layer The second polarizing layer is located on the side of the liquid crystal layer away from the backlight module;
  • the fingerprint identification signal is output by the photosensitive detection layer; the fingerprint identification signal is output by the photosensitive detection layer after receiving the reflected light of the point light source radiated to the finger; the photosensitive detection layer is located in the first polarizing layer Between and the second polarizing layer;
  • the fingerprint pattern of the finger is determined.
  • the fingerprint identification method provided by the embodiment of the present disclosure, according to the determined touch position, it is determined in the backlight module of the display device that the light-emitting area corresponding to the touch position is At least two
  • the determining the fingerprint pattern of the finger according to the fingerprint identification signal includes:
  • the fingerprint pattern is formed through image splicing processing.
  • determining the touch position of the finger on the display surface of the display device includes:
  • the touch position of the finger is determined according to the touch detection signal output by the touch detection layer in the display device.
  • the backlight module includes: a driving backplane, and a plurality of light emitting diodes evenly distributed on the driving backplane;
  • the controlling the backlight module to emit light only in the light-emitting area includes:
  • the light-emitting area satisfies the following formula:
  • S represents the maximum width of the light-emitting area
  • ⁇ c represents the critical angle of total reflection between the protective cover and the air
  • ⁇ represents the maximum light-emitting angle of the point light source
  • t1 represents that the second polarizing layer is away from the backlight
  • M represents the imaging magnification of the point light source
  • t3 represents the backlight module is close to the protective cover
  • h represents the surface of the liquid crystal layer facing away from the backlight module to the position of the photosensitive detection layer facing away from the backlight module. The distance between the surfaces on one side of the backlight module.
  • the size of the point light source is less than 0.5 mm ⁇ 0.5 mm.
  • the distance between adjacent light-emitting diodes in the backlight module is 100 ⁇ m;
  • the controlling the backlight module to emit light only in the light-emitting area includes:
  • the 13 ⁇ 13 light-emitting diode chips corresponding to the light-emitting area are controlled to emit light.
  • the backlight module is controlled to emit light only in the light-emitting area, and the liquid crystal layer in the deflection area is controlled
  • the deflection of liquid crystal molecules includes:
  • the backlight module is controlled to emit light only in the light-emitting area, and the liquid crystal molecules in the deflection area in the liquid crystal layer are controlled to deflect.
  • the embodiment of the present disclosure also provides a display device, including: a memory, and a processor coupled with the memory;
  • the processor is configured to execute the above fingerprint identification method based on instructions stored in the memory.
  • FIG. 1 is a flowchart of a fingerprint identification method provided in an embodiment of the disclosure
  • FIG. 2 is a schematic diagram of a cross-sectional structure of a display device in an embodiment of the present disclosure
  • FIG. 3 is a schematic diagram of a specific structure at a sub-pixel position in FIG. 2;
  • FIG. 4 is a schematic top view of the structure of the display device in an embodiment of the disclosure.
  • FIG. 5 is a schematic structural diagram of a backlight module in an embodiment of the disclosure.
  • Figure 6 is a simplified schematic diagram of the structure of Figure 2;
  • FIG. 7 is a schematic diagram of an optical path of a fingerprint identification process in an embodiment of the disclosure.
  • Fig. 8 is a schematic diagram of imaging of a point light source
  • FIG. 9 is a schematic diagram of another optical path in the fingerprint identification process in an embodiment of the disclosure.
  • FIG. 11 is a schematic diagram of a point light source formed in Experiment 8 in an embodiment of the disclosure.
  • FIG. 12 is a schematic diagram of a fingerprint image detected in Experiment 8 in an embodiment of the disclosure.
  • the photosensitive element is integrated in the liquid crystal display device.
  • the light source is controlled to emit light.
  • the light emitted by the light source is reflected to the photosensitive element, and the signal output by the photosensitive element is detected.
  • the fingerprint image of the finger is collected.
  • the photosensitive element has reached the signal saturation before receiving the light reflected by the finger, resulting in the failure of fingerprint recognition.
  • Table 1 The following is a comparative analysis of the influence of the stray light inside the display device on the signal amount of the photosensitive element in conjunction with Table 1.
  • Table 1 shows the analysis of the influence of the stray light inside the device on the signal amount of the photosensitive element
  • experiment 1 the liquid crystal cell upper substrate and the protective cover plate were not set in the display device, and the backlight module was closed.
  • the display device was not provided with the protective cover plate and white glass was set as the liquid crystal cell upper substrate , And the backlight module is in the open state. Comparing experiment 1 and experiment 2 we can see that because the white glass is set as the upper substrate of the liquid crystal cell in the display device, the signal of the photosensitive element is greatly increased after the backlight module is turned on, which can prove that, The reflected light of the white glass has an effect on the photosensitive element.
  • experiment three used the color film substrate as the upper substrate of the liquid crystal cell. Comparing experiment two and experiment three, it can be seen that because the color film substrate is set in the display device as the upper substrate of the liquid crystal cell, the signal amount of the photosensitive element is further increased. Therefore, it can be proved that, compared with white glass, the color film substrate has stronger reflection performance, emits more light to the photosensitive element, and saturates the signal amount of the photosensitive element.
  • embodiments of the present disclosure provide a display device and a fingerprint recognition method thereof.
  • a fingerprint identification method for a display device provided by an embodiment of the present disclosure, as shown in FIG. 1, includes:
  • S101 Determine the touch position of the finger on the display surface of the display device
  • the liquid crystal layer is located on the light emitting side of the backlight module ;
  • the fingerprint recognition signal is output by the photosensitive detection layer; the fingerprint recognition signal is output by the photosensitive detection layer after receiving the reflected light from the point light source to the finger; the photosensitive detection layer is located between the first polarizing layer and the second polarizing layer;
  • S105 Determine the fingerprint pattern of the finger according to the fingerprint identification signal.
  • the fingerprint identification method controls the backlight module to emit light only in the light-emitting area corresponding to the touched position, and controls the deflection of the liquid crystal molecules in the deflection area corresponding to the light-emitting area in the liquid crystal layer, so that the backlight module is After the light emitted from the light-emitting area passes through the first polarizing layer, the liquid crystal layer, and the second polarizing layer, a point light source is formed on the light-emitting surface of the second polarizing layer, thereby reducing the stray light inside the display device and alleviating the fingerprints caused by the stray light inside the display device.
  • the interference of the identification signal makes the photosensitive detection layer not reach the signal saturation before receiving the light reflected by the finger, so that the light emitted by the point light source is reflected by the finger and directed to the photosensitive detection layer. According to the fingerprint identification signal output by the photosensitive detection layer, we get The fingerprint pattern of the finger realizes accurate fingerprint recognition.
  • FIG. 2 is a schematic diagram of a cross-sectional structure of a display device in an embodiment of the disclosure
  • FIG. 3 is a schematic diagram of a specific structure at a sub-pixel position in FIG.
  • the schematic diagram of the structure of the backlight module in the embodiment is disclosed.
  • the structure of the display device in the embodiment of the present disclosure will be described in detail below with reference to FIGS. 2 to 5.
  • the display device in the embodiment of the present disclosure includes: a backlight module 2, an array substrate 3 on the side of the light emitting surface of the backlight module 2, and a color film on the side of the array substrate 3 away from the backlight module 2
  • the substrate 4 the liquid crystal layer 5 between the array substrate 3 and the color filter substrate 4, the first polarizing layer 61 on the side of the array substrate 3 close to the backlight module 2, and the first polarizing layer 61 on the side of the color filter substrate 4 away from the backlight module 2
  • the array substrate 3 includes: a first base substrate 30, a circuit layer 31 located on the first base substrate 30, and a photosensitive detection layer 32 located on the side of the circuit layer 31 away from the first base substrate 30.
  • the photosensitive detection layer 32 may include a plurality of photosensitive detection units 321.
  • the photosensitive detection unit 321 can be used as a photosensitive element to detect the light reflected by the finger, and each photosensitive detection unit 321 can be electrically connected to the circuit layer 31.
  • the fingerprint identification signal output by each photosensitive detection unit 321 can be independently controlled by the circuit layer 31.
  • the color filter substrate 4 includes: a second base substrate 40, a flat layer 41 located on the second base substrate 40, and a color filter layer 42 located on the side of the flat layer 41 away from the second base substrate 40, located on the color film
  • the layer 42 is away from the supporting pillar 43 on the side of the second base substrate 40.
  • the color film layer 42 can include a filter unit 421 and a light shielding unit 422.
  • the filter unit 421 can filter light so that light of a specific color is emitted at the sub-pixel position to achieve color display.
  • the light shielding unit 422 can shield the display device.
  • the signal wiring and the support column 43 can be arranged in the range of the shading unit 422 to avoid affecting the aperture ratio of the display device.
  • first polarizing layer 61 and the first base substrate 30 can be bonded by optically clear adhesive (OCA), and the second polarizing layer 62 and the second base substrate 40, and the second polarizing layer
  • OCA optically clear adhesive
  • the layer 62 and the protective cover 7 can also be bonded by optical glue.
  • the transmission axis directions of the first polarizing layer 61 and the second polarizing layer 62 are perpendicular to each other.
  • the touch position of the finger F is determined. According to the determined touch position, at least the touch position corresponding to the touch position is determined in the backlight module 2.
  • a light-emitting area P, and a deflection area N corresponding to the light-emitting area P is determined in the liquid crystal layer 5, the backlight module 2 is controlled to emit light only in the light-emitting area P, and the liquid crystal molecules in the deflection area N are controlled to deflect to make the backlight module 2
  • a point light source E is formed on the light exit surface of the second polarizing layer 62, and the light emitted by the point light source E is directed toward the finger F Afterwards, it is reflected by the finger F to the photosensitive detection layer 32. Since the valleys and ridges of the finger
  • FIG. 2 only one beam of light is directed to the photosensitive detection unit 321 for illustration, and the number of light reflected by the finger F is not limited. In specific implementation, the light reflected by the finger F can be directed in multiple directions. To multiple photosensitive detection units 321.
  • each photosensitive detection unit 321 may be disposed within the range of the light shielding unit 422.
  • the photosensitive detection unit 321 may be a PIN photosensitive diode or other photosensitive elements, which is not limited here.
  • the circuit layer 31 can include a first thin film transistor TFT1 and a second thin film transistor TFT2, etc., wherein the first thin film transistor TFT1 can be electrically connected to the pixel electrode 312, by controlling the pixel electrode 312 The voltage between the common electrode 311 and the common electrode 311 controls the deflection of the liquid crystal molecules in the liquid crystal layer 5.
  • the second thin film transistor TFT2 can be electrically connected to the photosensitive detection unit 321. During the fingerprint recognition process, the second thin film transistor TFT2 can read the photosensitive The fingerprint recognition signal output by the detection unit 321.
  • the first thin film transistor TFT1 and the second thin film transistor TFT2 are also provided on the side of the TFT2 close to the first base substrate 30.
  • the array substrate may also include a plurality of gate lines G and a plurality of data lines D.
  • the photosensitive detection unit 321 may be located above the gate line G, and the photosensitive detection unit 321 may be arranged in a rectangular shape. The side may be consistent with the extending direction of the gate line G, and the photosensitive detection unit 321 may also have other shapes, which are not limited here.
  • the above-mentioned backlight module may be a direct type backlight module.
  • the backlight module may include: a driving backplane 21, which is located between the driving backplane 21
  • the multiple light-emitting diodes 211 on the upper part the encapsulation layer 22 used to encapsulate the light-emitting diode 211, the quantum dot film 23 on the encapsulation layer 22, the first diffusion sheet 24 on the quantum dot film 23, and the first diffusion sheet
  • a plurality of light-emitting diodes 211 are uniformly distributed on the driving backplane 21, and the light-emitting diodes 211 may be mine light-emitting diodes.
  • FIG. 2 is simplified in FIG. 6 to more clearly illustrate the distribution of light.
  • the finger F touches the protective cover 7
  • determine the touch position of the finger F according to the determined touch position, determine in the backlight module 2 at least one light-emitting area P corresponding to the touched position, and determine the deflection area corresponding to the light-emitting area P in the liquid crystal layer 5 N.
  • the light-emitting diodes in the light-emitting area P of the backlight module 2 are controlled to emit light.
  • a high-level signal is applied to the light-emitting diodes in the light-emitting area P to light up the light-emitting diodes in the light-emitting area P.
  • Other areas in the backlight module 2 are in a silent state.
  • a high-level signal can be applied to the liquid crystal molecules in the deflection area N, so that the light emitted from the light-emitting area P can pass through the first polarizing layer, the liquid crystal layer, and the second polarizing layer. The polarizing layer is emitted.
  • the liquid crystal molecules in other regions of the liquid crystal layer 5 do not deflect.
  • low-level signals can be applied to the liquid crystal molecules in other regions to prevent light from being emitted from other regions, thereby forming a point light source E at the position of the second polarizing layer.
  • the point light source E continues to transmit upward to the fingerprint recognition interface, that is, the contact interface between the protective cover 7 and the finger F.
  • the light reflected and scattered at the fingerprint recognition interface is directed to the photosensitive detection unit 321, and the photosensitive detection unit 321 converts the light into electricity after receiving the light.
  • the fingerprint pattern can be determined by detecting the fingerprint identification signal output by the photosensitive detection unit 321.
  • step S102 according to the determined touch position, it is determined in the backlight module of the display device that there are at least two light-emitting areas corresponding to the touch position;
  • the foregoing step S105 may include:
  • a fingerprint pattern is formed through image splicing processing.
  • the number of light-emitting areas P in the backlight module 2 can be determined according to the contact area between the finger F and the protective cover 7.
  • a fingerprint pattern can be formed through image splicing processing. Get a more complete fingerprint pattern.
  • the above-mentioned step S101 may include:
  • the touch position of the finger is determined according to the touch detection signal output by the touch detection layer in the display device.
  • a touch detection layer can be provided in the display device, and an in-cell touch detection layer can be provided.
  • a touch detection layer can be provided in a color filter substrate or an array substrate, or a surface touch detection layer can also be covered. There is no limit. When the finger touches the display surface of the display device, the touch position of the finger can be determined according to the touch detection signal output by the touch detection layer.
  • the light-emitting area corresponding to the touch position can be determined according to the determined touch position.
  • the touch position determined according to the touch detection layer can be a certain coordinate value or a certain area.
  • the light-emitting area is set as an area including the touch position. For example, a certain range around the touch area can be taken as the light-emitting area.
  • the light-emitting area may be square or circular, or may have other shapes, which is not limited here.
  • the deflection area in the liquid crystal layer may be slightly smaller than the light-emitting area, or the deflection area may also be slightly larger than the light-emitting area, which can be set according to actual conditions.
  • the backlight module may include: a driving backplane 21, and a plurality of light emitting diodes 211 evenly distributed on the driving backplane 21;
  • controlling the backlight module to emit light only in the light-emitting area may include:
  • the light-emitting diode to be lit can be further determined according to the determined light-emitting area, which can be determined by combining the size of the light-emitting diode and the distance between adjacent light-emitting diodes. Therefore, in step S103, the direction can be determined
  • the determined light-emitting area which can be determined by combining the size of the light-emitting diode and the distance between adjacent light-emitting diodes. Therefore, in step S103, the direction can be determined
  • Each light-emitting diode that needs to be lighted applies a high-level signal to light each light-emitting diode, so that the backlight module emits light in the light-emitting area.
  • Figures 7 and 9 are schematic diagrams of the light path of the fingerprint identification process in the embodiments of the present disclosure.
  • Figure 8 is a schematic diagram of imaging of a point light source.
  • the light-emitting area P satisfies the following formula:
  • S represents the maximum width of the light-emitting area P
  • ⁇ c represents the critical angle of total reflection between the protective cover 7 and the air, generally about 42°
  • ⁇ represents the maximum light-emitting angle of the point light source E (and the maximum light-emitting area P The angle is the same)
  • t1 represents the distance from the surface of the second polarizing layer away from the backlight module 2 to the surface of the protective cover 7 away from the backlight module 2
  • M represents the imaging magnification of the point light source E
  • t3 represents The distance between the surface of the backlight module 2 on the side close to the protective cover 7 and the surface of the photosensitive detection layer 32 on the side close to the backlight module 2
  • h represents the surface of the liquid crystal layer on the side facing away from the backlight module 2 (ie, the color film substrate 4) the distance from the surface on the side close to the backlight module 2) to the surface on the side facing away from the backlight module 2 of the photosensitive detection layer 32.
  • the photosensitive detection unit In order to avoid the stray light inside the display device from interfering with the fingerprint recognition process, it is necessary to prevent light other than the light reflected by the finger from being directed to the photosensitive detection unit, that is to say, it is necessary to prevent the light emitted by the backlight module from being reflected by the internal film of the display device. To the photosensitive detection unit. Since the refractive index of most of the film layers in the display device is relatively similar, the reflection between the film layer interfaces can be ignored, and the color film substrate has a greater impact on the reflection of the light emitted by the backlight module. Therefore, in order to avoid stray light inside the display device The interference of the fingerprint recognition process needs to prevent the light emitted by the backlight module from being reflected by the color film substrate and then directed toward the photosensitive detection unit.
  • t represents the surface of the backlight module on the side close to the protective cover to the surface of the second polarizing layer on the side close to the protective cover.
  • W1 is the actual fingerprint area obtained by the point light source E directed to the fingerprint recognition interface (that is, the interface between the protective cover and the finger)
  • W2 represents the light emitted by the point light source E is reflected by the finger and formed on the photosensitive detection layer
  • the fingerprint image is located at the position of the photosensitive detection layer
  • the fingerprint image W2 is an enlarged image of the actual fingerprint area W1, as can be seen from Figure 8, the actual fingerprint area W1 and the fingerprint image W2 are both circular, and the actual fingerprint area W1
  • the inner edge of the fingerprint image W2 is formed by total reflection when the light hits the fingerprint recognition interface, and the outer edge is determined by the maximum light-emitting angle of the point light source E.
  • the imaging magnification of the point light source E can be calculated as follows: Sure:
  • the imaging size of the point light source E is: L1 ⁇ L2; where L1 is the outer diameter of the fingerprint image W2, L2 is the inner diameter of the fingerprint image W2, L1 and L2 can be determined according to the following formula:
  • S′ is the maximum radiation width when the light-emitting area P is transmitted to the plane where the photosensitive detection layer 32 is located
  • L3 represents the increase in light radiation after the light-emitting area P is reflected by the color film substrate 4 compared to the S′ light-emitting area P.
  • the critical angle ⁇ c of total reflection between the protective cover 7 and the air can be about 42°
  • the magnification M can be between 2.5-3
  • t can be 0.8mm-1mm.
  • t3 can be in the range of 0.3 mm to 0.5 mm
  • h can be in the range of 3 um to 5 um.
  • the size of the light-emitting area P can be obtained according to the actual thickness of each film layer in the display device.
  • 0 ⁇ S ⁇ 1.3mm that is, the maximum width of the light-emitting area P preferably does not exceed 1.3mm, and the size of the light-emitting area and the deflection area can also be controlled by ,
  • the size of the formed point light source E is less than or equal to 0.5 mm ⁇ 0.5 mm to prevent the light emitted from the light-emitting area P from being reflected by the color filter substrate 4 and directed toward the photosensitive detection layer 32.
  • the distance between adjacent light-emitting diodes in the backlight module is 100 ⁇ m;
  • controlling the backlight module to emit light only in the light-emitting area includes:
  • the maximum width of the light-emitting area does not exceed 1.3 mm, so that the light emitted from the light-emitting area cannot be directed toward the photosensitive detection layer after being reflected by the color film substrate.
  • the above-mentioned step S103 may include:
  • the backlight module is controlled to emit light only in the light-emitting area, and the liquid crystal molecules in the deflection area in the liquid crystal layer are controlled to deflect.
  • the fingerprint identification process and the display process can be performed in a time-sharing manner, and the fingerprint identification process can be prevented from affecting the display effect of the display device.
  • the embodiment of the present disclosure also provides four sets of comparative experiments for verification, which are described in detail below in conjunction with Table 2.
  • Comparing Experiment 6 and Experiment 7 shows that, compared with Experiment 6, controlling the backlight module to turn on only the light-emitting area in Experiment 7 can greatly reduce the signal amount of the photosensitive detection layer without reaching saturation, so that fingerprints can be identified.
  • FIGS. 10 to 12 show the actual test schematic diagrams in the eighth experiment, where Fig. 10 is a schematic diagram of the backlight module emitting light in the light-emitting area in the eighth experiment, and Fig. 11
  • FIG. 12 is a schematic diagram of a fingerprint image obtained by detection. It can be fully proved from FIGS. 10 to 12 that the fingerprint identification method provided by the embodiment of the present disclosure can accurately detect the fingerprint image.
  • the embodiments of the present disclosure also provide a display device, which can be applied to any product or component with display function such as mobile phones, tablet computers, televisions, monitors, notebook computers, digital photo frames, navigators, etc. . Since the principle of solving the problem of the display device is similar to the above-mentioned fingerprint identification method, the implementation of the display device can refer to the implementation of the above-mentioned fingerprint identification method, and the repetition will not be repeated.
  • the above-mentioned display device includes: a memory, and a processor coupled with the memory;
  • the processor is configured to execute the aforementioned fingerprint identification method based on instructions stored in the memory.
  • the display device and the fingerprint identification method provided by the implementation of the present disclosure control the backlight module to emit light only in the light-emitting area corresponding to the touched position, and control the deflection of the liquid crystal molecules in the deflection area corresponding to the light-emitting area in the liquid crystal layer, thereby enabling the backlight
  • a point light source is formed on the light exit surface of the second polarizing layer, thereby reducing the stray light inside the display device and alleviating the stray light inside the display device.
  • the interference of astigmatism on the fingerprint recognition signal makes the photosensitive detection layer not reach the signal saturation before receiving the light reflected by the finger, so that the light emitted by the point light source is reflected by the finger and directed to the photosensitive detection layer, and the fingerprint identification output by the photosensitive detection layer Signal, get the fingerprint pattern of the finger, and realize accurate fingerprint recognition.

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Abstract

显示装置及其指纹识别方法，控制背光模组（2）仅在与触摸位置对应的发光区域（P）发光，并控制液晶层（5）中与发光区域（P）对应的偏转区域（N）内的液晶分子偏转，使背光模组（2）在发光区域（P）出射的光线经第一偏光层（61）、液晶层（5）、第二偏光层（62）后，在第二偏光层（62）的出光面形成点光源（E），使光敏检测层（32）在接收手指（F）反射的光线之前未达到信号量饱和，使点光源（E）出射的光线经手指（F）反射后射向光敏检测层（32），根据光敏检测层（32）输出的指纹识别信号，得到手指的指纹图样。从而减少了显示装置内部的杂散光，缓解其对指纹识别信号的干扰，实现精确的指纹识别。

Description

显示装置及其指纹识别方法
相关申请的交叉引用
本公开要求在2020年06月08日提交中国专利局、申请号为202010511971.8、申请名称为“一种显示装置及其指纹识别方法”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及显示技术领域，尤指一种显示装置及其指纹识别方法。
背景技术
指纹识别作为一种生物识别方式，在保护个人隐私方面提供了巨大的作用，目前市场电子产品几乎都配备有指纹识别系统，例如汽车、手机、打卡机等都可以具备指纹识别功能。
发明内容
本公开实施例提供了一种显示装置的指纹识别方法，包括：
确定手指在所述显示装置的显示面的触摸位置；
根据确定的所述触摸位置，在所述显示装置的背光模组中确定与所述触摸位置对应的至少一个发光区域，以及在液晶层中确定与所述发光区域对应的偏转区域；所述液晶层位于所述背光模组的出光侧；
控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转，以使所述背光模组在所述发光区域出射的光线经第一偏光层、所述液晶层及第二偏光层后，在所述第二偏光层的出光面形成点光源；所述第一偏光层位于所述背光模组与所述液晶层之间，所述第二偏光层位于所述液晶层背离所述背光模组的一侧；
接收光敏检测层输出的指纹识别信号；所述指纹识别信号是由所述光敏 检测层接收所述点光源射向手指后的反射光后输出的；所述光敏检测层位于所述第一偏光层与所述第二偏光层之间；
根据所述指纹识别信号，确定手指的指纹图样。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，根据确定的所述触摸位置，在所述显示装置的背光模组中确定与所述触摸位置对应的发光区域为至少两个；
所述根据所述指纹识别信号，确定手指的指纹图样，包括：
根据所述指纹识别信号，通过图像拼接处理形成所述指纹图样。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，确定手指在所述显示装置的显示面的触摸位置，包括：
根据所述显示装置中的触控检测层输出的触控检测信号，确定手指的触摸位置。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，所述背光模组，包括：驱动背板，以及均匀分布于所述驱动背板的多个发光二极管；
所述控制所述背光模组仅在所述发光区域发光，包括：
控制所述发光区域中的各所述发光二极管发光。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，所述发光区域满足以下公式：
S≤2*tanθc*t1*M-2*t3*tanθ-4*h*tanθ；
其中，S表示所述发光区域的最大宽度，θc表示保护盖板与空气之间的全反射临界角，θ表示所述点光源的最大发光角度，t1表示所述第二偏光层背离所述背光模组一侧的表面至所述保护盖板背离所述背光模组一侧的表面之间的距离，M表示所述点光源的成像放大率，t3表示所述背光模组靠近所述保护盖板一侧的表面至所述光敏检测层靠近所述背光模组一侧的表面之间的距离；h表示所述液晶层背离所述背光模组一侧的表面至所述光敏检测层背离所述背光模组一侧的表面之间的距离。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，0＜S≤1.3mm。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，所述点光源的尺寸小于0.5mm×0.5mm。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，所述背光模组中相邻的发光二极管之间的间距为100μm；
所述控制所述背光模组仅在所述发光区域发光，包括：
控制与所述发光区域对应的13×13个所述发光二极管芯片发光。
在一种可能的实现方式中，在本公开实施例提供的指纹识别方法中，所述控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转，包括：
在相邻两帧显示时间段的间隔时间段内，控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转。
本公开实施例还提供了一种显示装置，包括：存储器，以及与所述存储器耦接的处理器；
所述处理器被配置为基于存储在所述存储器中的指令，执行上述指纹识别方法。
附图说明
图1为本公开实施例中提供的指纹识别方法的流程图；
图2本公开实施例中显示装置的截面结构示意图；
图3为图2中一个子像素位置处的具体结构示意图；
图4为本公开实施例中显示装置的俯视结构示意图；
图5为本公开实施例中背光模组的结构示意图；
图6为图2的简化结构示意图；
图7为本公开实施例中指纹识别过程的一种光路示意图；
图8为点光源的成像示意图；
图9为本公开实施例中指纹识别过程的另一种光路示意图；
图10为本公开实施例中实验八中背光模组在发光区域发光的示意图；
图11为本公开实施例中实验八中形成的点光源的示意图；
图12为本公开实施例中实验八中检测得到的指纹像的示意图。
具体实施方式
在相关技术中，将感光元件集成于液晶显示装置中，在指纹识别过程中，控制光源出射光线，手指触摸屏幕时会将光源出射的光线反射至感光元件，通过检测感光元件输出的信号，来采集手指的指纹像，然而，由于显示装置内部膜层对光线的反射，使感光元件在未接收到手指反射的光线时就已经达到信号量饱和，导致指纹识别失败。以下结合表1对显示装置内部杂散光对感光元件信号量的影响进行对比分析。
表1显示装置内部杂散光对感光元件信号量的影响分析表
  实验一 实验二 实验三 实验四
背光模组 关 开 开 开
第一偏光片 有 有 有 有
第二偏光片 有 有 有 有
液晶盒上基板 无 白玻璃 彩膜基板 彩膜基板
保护盖板 无 无 无 有
信号量 9500 22000 47000(饱和) 47000(饱和)
如表1所示，以四组实验来分析显示装置内部杂散光对感光元件信号量的影响，应该说明的是，上述实验一至实验四中，除表1中所列的不同点外，其余结构和参数相同，并且，表1中背光模组的状态为“开”，表示背光模组中的背光源全部开启。
在实验一中，显示装置中未设置液晶盒上基板及保护盖板，并且背光模组为关闭状态，在实验二中，显示装置中未设置保护盖板，设置了白玻璃作 为液晶盒上基板，并且背光模组为打开状态，对比实验一及实验二可知，由于显示装置中设置了白玻璃作为液晶盒上基板，打开背光模组后使感光元件的信号量大幅增加，由此可以证明，白玻璃的反射光对感光元件产生了影响。
相比于实验二，实验三中将彩膜基板作为液晶盒上基板，对比实验二和实验三可知，由于显示装置中设置了彩膜基板作为液晶盒上基板，感光元件的信号量进一步增大，由此可以证明，相比于白玻璃，彩膜基板的反射性能更强，将更多的光线发射至感光元件，使感光元件的信号量达到饱和。
相比于实验三，实验四中设置了保护盖板，对比实验三和实验四可知，由于彩膜基板和保护盖板的反射作用，使感光元件的信号量达到饱和。
由表1中的实验一至实验四可知，在光线还为从保护盖板的出光面射出时，由于显示装置内部膜层的反射，已经使感光元件的信号量达到饱和，在指纹识别过程中，显示装置内部的杂散光对检测结果的干扰较大，甚至造成指纹识别失败。
基于此，针对相关技术中存在的由于显示装置内部杂散光的干扰导致指纹识别失败的问题，本公开实施例提供了一种显示装置及其指纹识别方法。
下面结合附图，对本公开实施例提供的显示装置及其指纹识别方法的具体实施方式进行详细地说明。附图中各膜层的厚度和形状不反映真实比例，目的只是示意说明本公开内容。
本公开实施例提供的一种显示装置的指纹识别方法，如图1所示，包括：
S101、确定手指在显示装置的显示面的触摸位置；
S102、根据确定的触摸位置，在显示装置的背光模组中确定与触摸位置对应的至少一个发光区域，以及在液晶层中确定与发光区域对应的偏转区域；液晶层位于背光模组的出光侧；
S103、控制背光模组仅在发光区域发光，并控制液晶层中偏转区域中的液晶分子偏转，以使背光模组在发光区域出射的光线经第一偏光层、液晶层及第二偏光层后，在第二偏光层的出光面形成点光源；第一偏光层位于背光模组与液晶层之间，第二偏光层位于液晶层背离背光模组的一侧；
S104、接收光敏检测层输出的指纹识别信号；指纹识别信号是由光敏检测层接收点光源射向手指后的反射光后输出的；光敏检测层位于第一偏光层与第二偏光层之间；
S105、根据指纹识别信号，确定手指的指纹图样。
本公开实施例提供的指纹识别方法，通过控制背光模组仅在与触摸位置对应的发光区域发光，并控制液晶层中与发光区域对应的偏转区域内的液晶分子偏转，从而使背光模组在发光区域出射的光线经第一偏光层、液晶层、第二偏光层后，在第二偏光层的出光面形成点光源，从而减少了显示装置内部的杂散光，缓解显示装置内部杂散光对指纹识别信号的干扰，使光敏检测层在接收手指反射的光线之前未达到信号量饱和，从而使点光源出射的光线经手指反射后射向光敏检测层，根据光敏检测层输出的指纹识别信号，得到手指的指纹图样，实现精确的指纹识别。
图2为本公开实施例中显示装置的截面结构示意图，图3为图2中一个子像素位置处的具体结构示意图，图4为本公开实施例中显示装置的俯视结构示意图，图5为本公开实施例中背光模组的结构示意图。以下结合图2至图5，对本公开实施例中的显示装置的结构进行详细说明。
如图2所示，本公开实施例中的显示装置，包括：背光模组2，位于背光模组2出光面一侧的阵列基板3，位于阵列基板3背离背光模组2一侧的彩膜基板4，位于阵列基板3与彩膜基板4之间的液晶层5，位于阵列基板3靠近背光模组2一侧的第一偏光层61，位于彩膜基板4背离背光模组2一侧的第二偏光层62，以及位于第二偏光层62背离背光模组2一侧的保护盖板7。
其中，阵列基板3包括：第一衬底基板30，位于第一衬底基板30之上的线路层31，以及位于线路层31背离第一衬底基板30一侧的光敏检测层32。光敏检测层32可以包括多个光敏检测单元321，在指纹识别过程中，光敏检测单元321可以作为感光元件，检测手指反射的光线，并且，各光敏检测单元321可以与线路层31电连接，在指纹识别过程中，可以通过线路层31独权各光敏检测单元321输出的指纹识别信号。
彩膜基板4包括：第二衬底基板40，位于第二衬底基板40之上的平坦层41，以及位于平坦层41背离第二衬底基板40一侧的彩膜层42，位于彩膜层42背离第二衬底基板40一侧的支撑柱43。彩膜层42可以包括滤光单元421及遮光单元422，滤光单元421可以对光线进行过滤，以使子像素位置处出射特定颜色的光线，从而实现彩色显示，遮光单元422可以遮挡显示装置中影响开口率的部件，例如可以将信号走线、支撑柱43设置在遮光单元422的范围内，避免影响显示装置的开口率。
在具体实施时，第一偏光层61与第一衬底基板30之间可以通过光学胶(Optically Clear Adhesive，OCA)粘合，第二偏光层62与第二衬底基板40，以及第二偏光层62与保护盖板7之间也可以通过光学胶粘合。并且，第一偏光层61与第二偏光层62的透过轴方向相互垂直。
参照图2，本公开实施例中，当检测到手指F触摸保护盖板7的表面时，确定手指F的触摸位置，根据确定的触摸位置，在背光模组2中确定与触摸位置对应的至少一个发光区域P，以及在液晶层5中确定与发光区域P对应的偏转区域N，控制背光模组2仅在发光区域P发光，并控制偏转区域N中的液晶分子偏转，以使背光模组2在发光区域P出射的光线经第一偏光层61、液晶层5及第二偏光层62后，在第二偏光层62的出光面形成点光源E，点光源E出射的光线射向手指F后，被手指F反射至光敏检测层32，由于手指F的谷和脊反射的光线强度不同，从而可以根据光敏检测层32输出的指纹识别信号，确定手指的指纹图样。
应该说明的是，图2中仅以一束光线射向光敏检测单元321为例进行示意，并不限定手指F反射光线的数量，在具体实施时，手指F反射的光线可以朝多个方向射向多个光敏检测单元321。
此外，图2中以光敏检测层32位于阵列基板3中为例进行示意，在具体实施时，光敏检测层32也可以设置在其他位置，例如可以设置于彩膜基板4中。并且，为了避免光敏检测层32影响显示装置的开口率，可以将各光敏检测单元321设置于遮光单元422的范围内。具体地，光敏检测单元321可以 为PIN光敏二极管，也可以为其他感光元件，此处不做限定。
同时参照图3，在阵列基板3中，线路层31可以包括第一薄膜晶体管TFT1及第二薄膜晶体管TFT2等结构，其中，第一薄膜晶体管TFT1可以与像素电极312电连接，通过控制像素电极312与公共电极311之间的电压，来控制液晶层5中的液晶分子偏转，第二薄膜晶体管TFT2可以与光敏检测单元321电连接，在指纹识别过程中，可以通过第二薄膜晶体管TFT2读取光敏检测单元321输出的指纹识别信号。此外，为了避免光线从第一衬底基板30一侧射向第一薄膜晶体管TFT1和第二薄膜晶体管TFT2，而产生光生电流影响薄膜警惕感的性能，在第一薄膜晶体管TFT1和第二薄膜晶体管TFT2靠近第一衬底基板30的一侧还设有遮光层33。
如图4所示，阵列基板还可以包括多条栅线G以及多条数据线D，光敏检测单元321可以位于栅线G的上方，光敏检测单元321可以设置为长方形，光敏检测单元321的长边可以与栅线G的延伸方向一致，光敏检测单元321也可以为其他形状，此处不做限定。
本公开实施例中，为了便于控制背光模组仅在发光区域发光，上述背光模组可以为直下式背光模组，具体地，背光模组可以包括：驱动背板21，位于驱动背板21之上的多个发光二极管211，用于封装发光二极管211的封装层22，位于封装层22之上的量子点膜23，位于量子点膜23之上的第一扩散片24，位于第一扩散片24之上的第一棱镜片25，位于第一棱镜片25之上的第二棱镜片26，位于第二棱镜片26之上的第二扩散片。多个发光二极管211均匀分布于驱动背板21之上，发光二极管211可以为微型(Mine)发光二极管。
为了更清楚的示意本公开实施例中指纹识别发光的过程，图6中对图2的结构进行了简化，以更清楚的示意光线的分布，具体地，当检测到手指F触摸保护盖板7的表面时，确定手指F的触摸位置，根据确定的触摸位置，在背光模组2中确定与触摸位置对应的至少一个发光区域P，以及在液晶层5中确定与发光区域P对应的偏转区域N。控制背光模组2的发光区域P中的 发光二极管发光，具体地，向发光区域P中的发光二极管施加高电平信号，以点亮发光区域P中的发光二极管。背光模组2中的其他区域(如图中的区域Q1和Q2)处于静默状态。控制液晶层5中偏转区域N中的液晶分子偏转，例如可以向偏转区域N的液晶分子施加高电平信号，从而使发光区域P出射的光线能够穿过第一偏光层、液晶层、第二偏光层而射出。而液晶层5中其他区域的液晶分子不发生偏转，例如可以向其他区域的液晶分子施加低电平信号，使光线无法从其他区域射出，从而在第二偏光层的位置处形成点光源E。点光源E向上继续传输射向指纹识别界面，即保护盖板7与手指F的接触界面，在指纹识别界面反射与散射的光线射向光敏检测单元321，光敏检测单元321接收光线后转换为电信号，由于手指F谷和脊反射的光线强度不同，因此，可以通过检测光敏检测单元321输出的指纹识别信号，来确定指纹图样。
在具体实施时，本公开实施例提供的上述指纹识别方法中，上述步骤S102中，根据确定的触摸位置，在显示装置的背光模组中确定与触摸位置对应的发光区域为至少两个；
上述步骤S105，可以包括：
根据指纹识别信号，通过图像拼接处理形成指纹图样。
可以根据手指F与保护盖板7的接触面积，来确定背光模组2中发光区域P的个数，当发光区域P的个数大于等于两个时，可以通过图像拼接处理形成指纹图样，以得到较完整的指纹图样。
具体地，本公开实施例提供的上述指纹识别方法中，上述步骤S101，可以包括：
根据显示装置中的触控检测层输出的触控检测信号，确定手指的触摸位置。
在显示装置中可以设置触控检测层，可以设置内嵌式触控检测层，例如可以在彩膜基板内或阵列基板内设置触控检测层，或者也可以覆盖表面式触控检测层，此处不做限定。当手指触摸显示装置的显示面时，可以根据触控检测层输出的触控检测信号，确定手指的触摸位置。
在上述步骤S102中，可以根据确定出的触摸位置，确定与该触摸位置对应的发光区域，具体地，根据触摸检测层确定的触摸位置可以为某个坐标值也可以为某个区域，可以将发光区域设置为包括触摸位置的区域，例如可以取触摸区域周围一定范围作为发光区域，发光区域可以为方形也可以为圆形，或者也可以为其他形状，此处不做限定。并且，为了便于形成点光源，液晶层中的偏转区域可以稍小于发光区域，或者也偏转区域也可以稍大于发光区域，可以根据实际情况来设置。
具体地，本公开实施例提供的上述指纹识别方法中，参照图5，背光模组，可以包括：驱动背板21，以及均匀分布于驱动背板21的多个发光二极管211；
上述步骤S103中，控制背光模组仅在发光区域发光，可以包括：
控制发光区域中的各发光二极管发光。
在具体实施时，可以根据确定的发光区域，进一步确定需要点亮的发光二极管，可以结合发光二极管的大小及相邻发光二极管之间的间距来确定，因而，在步骤S103中，可以向确定出的需要点亮的各发光二极管施加高电平信号，以点亮各发光二极管，使背光模组在发光区域发光。
图7和图9为本公开实施例中指纹识别过程的光路示意图，图8为点光源的成像示意图，结合图7至图9，本公开实施例提供的指纹识别方法中，发光区域P满足以下公式：
S≤2*tanθ c*t1*M-2*t3*tanθ-4*h*tanθ      (1)；
其中，S表示发光区域P的最大宽度，θc表示保护盖板7与空气之间的全反射临界角，一般为42°左右，θ表示点光源E的最大发光角度(与发光区域P的最大发光角度一致)，t1表示第二偏光层背离背光模组2一侧的表面至保护盖板7背离背光模组2一侧的表面之间的距离，M表示点光源E的成像放大率，t3表示背光模组2靠近保护盖板7一侧的表面至光敏检测层32靠近背光模组2一侧的表面之间的距离；h表示液晶层背离背光模组2一侧的表面(即彩膜基板4靠近背光模组2一侧的表面)至光敏检测层32背离背光模组2一侧的表面之间的距离。
当发光区域P满足上述公式时，可以避免显示装置内部杂散光对指纹识别结果的干扰，以下结合图7至图9对上述公式的推导过程进行详细说明。
为了避免显示装置内部杂散光对指纹识别过程的干扰，需要避免手指反射的光线以外的光线射向光敏检测单元，也就是说，需要避免背光模组出射的光线经显示装置内部膜层反射后射向光敏检测单元。由于显示装置中大部分膜层的折射率比较相近，膜层界面之间的反射可以忽略，对背光模组出射的光线反射影响较大为彩膜基板，因而，为了避免显示装置内部杂散光对指纹识别过程的干扰，需要避免背光模组出射的光线经彩膜基板反射后射向光敏检测单元。
由图7中的几何关系可以得到：
S＝2*t*tanθ          (2)；
其中，t表示背光模组靠近保护盖板一侧的表面至第二偏光层靠近保护盖板一侧的表面。
如图8所示，W1为点光源E射向指纹识别界面(即保护盖板与手指接触的界面)得到的实际指纹区域，W2表示点光源E出射的光线经手指反射后在光敏检测层形成的指纹像，指纹像W2位于光敏检测层的位置处，指纹像W2为实际指纹区域W1的放大像，从图8可以看出，实际指纹区域W1与指纹像W2均为环形，实际指纹区域W1与指纹像W2的内边缘是由于光线射向指纹识别界面时发生全反射形成的，外边缘是由点光源E的最大发光角度确定的。结合图7，可知点光源E与实际指纹区域W1之间的距离为t1，实际指纹区域W1与指纹像W2之间的距离为t1+t2，因而，点光源E的成像放大率可以按以下公式确定：
M＝(t1+t2)/t1       (3)；
点光源E的成像大小为：L1～L2；其中L1为指纹像W2的外部直径，L2为指纹像W2的内部直径，L1与L2可以按以下公式确定：
L1＝2*tanθ*t1*M     (4)；
L2＝2*tanθc*t1*M    (5)；
图9为发光区域P发出的光线经彩膜基板4反射后，射向光敏检测层32的边缘的临界状态，参照图9，为了使发光区域P发出的光线经彩膜基板4反射后，无法射向光敏检测层32，需满足以下关系式：
S′+2*L3≤L2      (6)；
S′＝S+2t3*tanθ    (7)；
L3＝2*h*tanθ       (8)；
其中，S′为发光区域P传输至光敏检测层32所在的平面时的最大辐射宽度，L3表示相比于S′发光区域P经彩膜基板4反射后的光线辐射增幅。
结合上述公式(2)～(8)可以得出上述公式(1)。
在具体实施时，本公开实施例中，保护盖板7与空气之间的全反射临界角θc可以为42°左右，放大率M可以在2.5～3之间，t可以在0.8mm～1mm的范围内，t3可以在0.3mm～0.5mm的范围内，h可以在3um～5um的范围内，可以根据显示装置中各膜层的实际厚度，得到发光区域P的尺寸。
具体地，本公开实施例提供的上述指纹识别方法中，0＜S≤1.3mm，也就是说，发光区域P的最大宽度最好不超过1.3mm，也可以通过控制发光区域及偏转区域的尺寸，使形成的点光源E的尺寸小于或等于0.5mm×0.5mm，以防止发光区域P出射的光线经彩膜基板4反射后，射向光敏检测层32。
在具体实施时，本公开实施例提供的上述指纹识别方法中，背光模组中相邻的发光二极管之间的间距为100μm；
上述步骤S103中，控制背光模组仅在发光区域发光，包括：
控制与发光区域对应的13×13个发光二极管芯片发光。
这样，可以保证发光区域的最大宽度不超过1.3mm，使发光区域出射的光线经彩膜基板反射后，无法射向光敏检测层。
在实际应用中，本公开实施例提供的上述指纹识别方法中，上述步骤S103，可以包括：
在相邻两帧显示时间段的间隔时间段内，控制背光模组仅在发光区域发光，并控制液晶层中偏转区域中的液晶分子偏转。
这样，可以使指纹识别过程与显示过程分时进行，可以防止指纹识别过程影响显示装置的显示效果。
为了证明本公开实施例提供的指纹识别方法，可以缓解显示装置内部杂散光对指纹识别过程的影响，本公开实施例还提供了四组对比实验进行验证，以下结合表2进行详细说明。
表2显示装置内部杂散光对指纹识别过程的影响分析表
  实验五 实验六 实验七 实验八
背光模组 关 全开 仅发光区域开 仅发光区域开
第一偏光片 有 有 有 有
第二偏光片 有 有 有 有
液晶盒上基板 彩膜基板 彩膜基板 彩膜基板 彩膜基板
光敏检测层 有 有 有 有
保护盖板 无 无 无 有
是否有手指触摸 无 无 无 有
信号量 8700 48000(饱和) 30000(未饱和) 28000
如表2所示，应该说明的是，上述实验五至实验八中，除表中所列的不同点外，其余结构和参数相同。对比实验五和实验六可知，实验六中将背光模组全部打开，使光敏检测层的信号量大幅增加，并达到饱和，从而证明，背光模组全部打开时，显示装置内部的杂散光对检测结果的干扰较大。
对比实验六和实验七可知，与实验六相比，实验七中控制背光模组仅发光区域打开，可以使光敏检测层的信号量大幅降低，没有达到饱和，从而可以识别指纹。
对比实验七和实验八可知，实验八中手指触摸显示装置的显示面时，由于手指对光线的影响，使光敏检测层的信号量有一定程度的降低，从而可以通过光敏检测层的信号量变化，得到手指的指纹图样，从而证明了本公开实施例提供的指纹识别方法，可以缓解显示装置内部杂散光对指纹识别过程的 影响，提高指纹识别的精确度。
为了进一步证明本公开实施例提供的指纹识别方法的效果，图10至图12示出了实验八中的实测示意图，其中，图10为实验八中背光模组在发光区域发光的示意图，图11为形成的点光源的示意图，图12为检测得到的指纹像的示意图，由图10至图12可以充分证明，本公开实施例提供的指纹识别方法能够准确检测指纹图像。
基于同一发明构思，本公开实施例还提供了一种显示装置，该显示装置可以应用于手机、平板电脑、电视机、显示器、笔记本电脑、数码相框、导航仪等任何具有显示功能的产品或部件。由于该显示装置解决问题的原理与上述指纹识别方法相似，因此该显示装置的实施可以参见上述指纹识别方法的实施，重复之处不再赘述。
本公开实施例提供的上述显示装置，包括：存储器，以及与存储器耦接的处理器；
处理器被配置为基于存储在存储器中的指令，执行上述指纹识别方法。
本公开实施提供的显示装置及其指纹识别方法，通过控制背光模组仅在与触摸位置对应的发光区域发光，并控制液晶层中与发光区域对应的偏转区域内的液晶分子偏转，从而使背光模组在发光区域出射的光线经第一偏光层、液晶层、第二偏光层后，在第二偏光层的出光面形成点光源，从而减少了显示装置内部的杂散光，缓解显示装置内部杂散光对指纹识别信号的干扰，使光敏检测层在接收手指反射的光线之前未达到信号量饱和，从而使点光源出射的光线经手指反射后射向光敏检测层，根据光敏检测层输出的指纹识别信号，得到手指的指纹图样，实现精确的指纹识别。
显然，本领域的技术人员可以对本公开进行各种改动和变型而不脱离本公开的精神和范围。这样，倘若本公开的这些修改和变型属于本公开权利要求及其等同技术的范围之内，则本公开也意图包含这些改动和变型在内。

Claims (10)

  1. 一种显示装置的指纹识别方法，其中，包括：
    确定手指在所述显示装置的显示面的触摸位置；
    根据确定的所述触摸位置，在所述显示装置的背光模组中确定与所述触摸位置对应的至少一个发光区域，以及在液晶层中确定与所述发光区域对应的偏转区域；所述液晶层位于所述背光模组的出光侧；
    控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转，以使所述背光模组在所述发光区域出射的光线经第一偏光层、所述液晶层及第二偏光层后，在所述第二偏光层的出光面形成点光源；所述第一偏光层位于所述背光模组与所述液晶层之间，所述第二偏光层位于所述液晶层背离所述背光模组的一侧；
    接收光敏检测层输出的指纹识别信号；所述指纹识别信号是由所述光敏检测层接收所述点光源射向手指后的反射光后输出的；所述光敏检测层位于所述第一偏光层与所述第二偏光层之间；
    根据所述指纹识别信号，确定手指的指纹图样。
  2. 如权利要求1所述的指纹识别方法，其中，根据确定的所述触摸位置，在所述显示装置的背光模组中确定与所述触摸位置对应的发光区域为至少两个；
    所述根据所述指纹识别信号，确定手指的指纹图样，包括：
    根据所述指纹识别信号，通过图像拼接处理形成所述指纹图样。
  3. 如权利要求1所述的指纹识别方法，其中，确定手指在所述显示装置的显示面的触摸位置，包括：
    根据所述显示装置中的触控检测层输出的触控检测信号，确定手指的触摸位置。
  4. 如权利要求1所述的指纹识别方法，其中，所述背光模组，包括：驱动背板，以及均匀分布于所述驱动背板的多个发光二极管；
    所述控制所述背光模组仅在所述发光区域发光，包括：
    控制所述发光区域中的各所述发光二极管发光。
  5. 如权利要求1所述的指纹识别方法，其中，所述发光区域满足以下公式：
    S≤2*tanθc*t1*M-2*t3*tanθ-4*h*tanθ；
    其中，S表示所述发光区域的最大宽度，θc表示保护盖板与空气之间的全反射临界角，θ表示所述点光源的最大发光角度，t1表示所述第二偏光层背离所述背光模组一侧的表面至所述保护盖板背离所述背光模组一侧的表面之间的距离，M表示所述点光源的成像放大率，t3表示所述背光模组靠近所述保护盖板一侧的表面至所述光敏检测层靠近所述背光模组一侧的表面之间的距离；h表示所述液晶层背离所述背光模组一侧的表面至所述光敏检测层背离所述背光模组一侧的表面之间的距离。
  6. 如权利要求5所述的指纹识别方法，其中，0＜S≤1.3mm。
  7. 如权利要求6所述的指纹识别方法，其中，所述点光源的尺寸小于0.5mm×0.5mm。
  8. 如权利要求6所述的指纹识别方法，其中，所述背光模组中相邻的发光二极管之间的间距为100μm；
    所述控制所述背光模组仅在所述发光区域发光，包括：
    控制与所述发光区域对应的13×13个所述发光二极管芯片发光。
  9. 如权利要求1所述的指纹识别方法，其中，所述控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转，包括：
    在相邻两帧显示时间段的间隔时间段内，控制所述背光模组仅在所述发光区域发光，并控制所述液晶层中所述偏转区域中的液晶分子偏转。
  10. 一种显示装置，其中，包括：存储器，以及与所述存储器耦接的处理器；
    所述处理器被配置为基于存储在所述存储器中的指令，执行如权利要求 1～9任一项所述的指纹识别方法。
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