CN111108512A

CN111108512A - Fingerprint recognition device under screen, fingerprint recognition system under screen, backlight module and liquid crystal display screen

Info

Publication number: CN111108512A
Application number: CN201980004393.4A
Authority: CN
Inventors: 李顺展; 李家成; 青小刚; 曾红林
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2020-05-05
Also published as: WO2021097707A1

Abstract

The application provides fingerprint recognition device and system under screen, backlight unit and liquid crystal display. Fingerprint recognition device is applicable to the electronic equipment who has liquid crystal display under the screen, fingerprint recognition device is including the fingerprint identification module that is located liquid crystal display's backlight unit below under the screen, backlight unit includes diffusion barrier and the adjacent light guide plate that sets up in the diffusion barrier below, the diffusion barrier is faced the microstructure that has a plurality of interval distribution to the surface of light guide plate, the microstructure is used for increasing the interval between diffusion barrier and the light guide plate, avoid the fingerprint to detect the light and produce the film interference phenomenon when seeing through between diffusion barrier and the light guide plate. The utility model provides a fingerprint recognition device under screen can eliminate or alleviate the film interference phenomenon that backlight unit produced, guarantees fingerprint imaging effect.

Description

Fingerprint recognition device under screen, fingerprint recognition system under screen, backlight module and liquid crystal display screen

Technical Field

The application relates to the technical field of fingerprint identification, especially, relate to a fingerprint identification device and system, backlight unit and liquid crystal display under screen.

Background

Fingerprint identification and unlocking become functions equipped in most mobile terminals such as mobile phones and tablet computers, and since a Liquid Crystal Display (LCD) screen has the advantages of thin thickness, point saving, no radiation and the like, the technology for identifying fingerprints under an optical screen of a mobile terminal adopting the LCD screen is advancing to commercialization.

The LCD screen usually includes a backlight module and a display module located above the backlight module, and generally, the optical film of the backlight module includes a reflective film, a light guide plate, a diffusion film and a brightness enhancement film which are arranged between a back plate and the display panel and sequentially stacked from bottom to top, and the films of the layers have different functions. The backlight module provides visible light through the backlight lamp, and the visible light forms an evenly distributed surface light source after being processed by each layer of optical film of the backlight module so as to evenly illuminate the display module of the LCD screen, thereby displaying pictures through the display module.

However, the thickness of each layer of optical film in the backlight module of the LCD screen is thin, and there is an air gap between adjacent optical films, the thin optical film is easy to deform, and then an uneven air gap is formed, which may cause the optical path difference of light propagating between each layer of optical film, and easily generate the film interference phenomenon. Because the fingerprint sensor can receive the interference lines generated by the interference of the thin film, the imaging effect of fingerprint identification can be seriously interfered.

Disclosure of Invention

The application provides fingerprint recognition device and system, backlight unit and liquid crystal display under screen can eliminate or alleviate the film interference phenomenon that backlight unit produced, guarantees fingerprint imaging effect.

In a first aspect, the present application provides an off-screen fingerprint identification apparatus, which is suitable for an electronic device having a liquid crystal display screen, wherein a fingerprint detection area of the off-screen fingerprint identification apparatus is at least partially located in a display area of the liquid crystal display screen;

the under-screen fingerprint identification device comprises a fingerprint identification module positioned below a backlight module of the liquid crystal display screen, wherein the fingerprint identification module is used for receiving fingerprint detection light which is formed by the reflection of a finger above a fingerprint detection area and penetrates through the liquid crystal display screen so as to acquire a fingerprint image of the finger;

the backlight module comprises a diffusion film and a light guide plate adjacently arranged below the diffusion film, the diffusion film faces the surface of the light guide plate and is provided with a plurality of microstructures which are distributed at intervals, the microstructures are used for increasing the distance between the diffusion film and the light guide plate, and the phenomenon of film interference generated when fingerprint detection light penetrates between the diffusion film and the light guide plate is avoided.

In one embodiment of the present application, the microstructure is a raised structure formed on the surface of the diffusion film.

In one embodiment of the present application, the microstructures are hemispherical convex structures.

In one embodiment of the present application, the diameter of the microstructures is between 120-170 μm and the height of the microstructures is between 1-3 μm.

In one embodiment of the present application, the plurality of microstructures are uniformly spaced on the surface of the diffusion film.

In one embodiment of the present application, the plurality of microstructures are uniformly spaced along the length direction and the width direction of the diffusion film.

In one embodiment of the present application, the pitch between every two adjacent rows of microstructures is equal to the pitch between every two adjacent columns of microstructures.

In a specific embodiment of the present application, the plurality of microstructures are uniformly arranged along the length direction of the diffusion film at intervals, the distances between every two adjacent rows of microstructures are equal, and the microstructures between every two adjacent rows are staggered.

In one embodiment of the present application, the microstructures are equidistant from two microstructures of an adjacent row that are offset from each other.

In one embodiment of the present application, a pitch between two adjacent microstructures in two adjacent rows is equal to a pitch between two adjacent microstructures in the same row.

In one embodiment of the present application, the pitch between two adjacent rows of microstructures is between 200 and 450 μm.

In one embodiment of the present application, the surface of the light guide plate facing the diffusion film has a plurality of raised light guide strips, the light guide strips extend along the width direction of the light guide plate, and the plurality of light guide strips are uniformly spaced along the length direction of the light guide plate.

In one embodiment of the present application, the light guide strip extends from one side to the other side of the light guide plate in the width direction.

In one embodiment of the present application, the cross section of the light guide bar is circular arc.

In one embodiment of the present application, the radius of curvature of the cross-section of the light guide bar is between 30-150 μm and the height of the light guide bar is between 1-5 μm.

In one embodiment of the present application, the distance between the centerlines of two adjacent light guide bars is between 40-150 μm.

In one embodiment of the present application, a surface of the light guide plate facing away from the diffusion film has a plurality of light guide particles distributed at intervals, and the light guide particles are supported between the light guide plate and the reflective film of the backlight module.

In one embodiment of the present application, the height of the light guiding particles is between 3-5 μm.

In one embodiment of the present application, the light guide plate has a different density of light guide particles at different regions of the surface of the light guide plate facing away from the diffuser film.

In one embodiment of the present application, the backlight module further comprises a brightness enhancement film disposed adjacent to the diffuser film, wherein a surface of the brightness enhancement film facing the diffuser film has a plurality of brightness enhancement particles spaced apart from each other.

In one embodiment of the present application, the brightness enhancing particles are microsphere structures embedded in the brightness enhancing film and have a diameter between 4-10 μm.

In one embodiment of the present application, the brightness enhancing particles are uniformly distributed across the surface of the brightness enhancing film.

In a specific implementation of this application, fingerprint recognition device still includes the detection light source under the screen, and the detection light source is used for launching the probe light, and the probe light passes through liquid crystal display and shines the finger above the fingerprint detection area, and the fingerprint detection light that carries fingerprint information is formed to the reflection of finger.

In an embodiment of the present application, the detection light has a different wavelength from a backlight provided by the backlight module for displaying a picture.

In an embodiment of the present application, the detection light is infrared light, and the backlight provided by the backlight module is visible light.

The second aspect, the application provides a backlight unit, the liquid crystal display who is applicable to and supports fingerprint recognition function under the screen, backlight unit includes diffusion barrier and adjacent light guide plate that sets up in the diffusion barrier below, and the diffusion barrier faces the micro-structure that has a plurality of interval distribution to the surface of light guide plate, and the micro-structure is used for increasing the interval between diffusion barrier and the light guide plate, avoids fingerprint detection light to produce light interference when seeing through between diffusion barrier and the light guide plate.

In one embodiment of the present application, the radius of curvature of the microstructures is between 120-170 μm and the height of the microstructures is between 1-3 μm.

In a third aspect, the application provides a fingerprint identification system under screen, including liquid crystal display and as above any fingerprint identification device under screen, liquid crystal display includes display module and as above any backlight unit, wherein, backlight unit is located the display module below.

In a fourth aspect, the application provides a support liquid crystal display of fingerprint identification function under screen, liquid crystal display's below be provided with as above arbitrary the screen fingerprint identification device under, liquid crystal display include display module assembly and as above arbitrary backlight unit, backlight unit is located the display module assembly below for display module assembly provides backlight, and detect the fingerprint detection optical transmission to the fingerprint sensor of backlight unit below with the finger formation of liquid crystal display top.

According to the under-screen fingerprint identification device and system, the backlight module and the liquid crystal display screen, the under-screen fingerprint identification device is suitable for electronic equipment with the liquid crystal display screen, and the fingerprint detection area of the under-screen fingerprint identification device is at least partially located in the display area of the liquid crystal display screen; fingerprint identification device includes the fingerprint identification module under the screen, and the fingerprint identification module is located liquid crystal display's backlight unit below, and the fingerprint detection light that carries fingerprint information of the finger reflection of fingerprint detection area top sees through liquid crystal display and transmits to fingerprint sensor, receives and discerns fingerprint image through fingerprint sensor. Wherein, backlight unit is including range upon range of diffusion barrier and the light guide plate that sets up, the light guide plate is located the diffusion barrier below, through set up a plurality of interval distribution's micro-structure on the surface towards light guide plate one side at the diffusion barrier, a plurality of micro-structures support between diffusion barrier and light guide plate, the micro-structure can increase the interval between diffusion barrier and the light guide plate, and then the air gap between diffusion barrier and the light guide plate has been increased, and can make the air gap of each position more even, and then can avoid fingerprint detection light to produce the film interference phenomenon when seeing through between diffusion barrier and the light guide plate, can eliminate the interference light that produces by the film interference phenomenon to fingerprint imaging's interference, guarantee fingerprint imaging effect, so that fingerprint sensor obtains clear fingerprint image.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings required for describing the embodiments or the prior art, and it is obvious that the drawings in the following description are some embodiments of the present application. For a person skilled in the art, without inventive effort, further figures can be obtained from these figures.

FIG. 1 is a schematic diagram of an underscreen fingerprint identification system;

FIG. 2 is a schematic view of a local deformation of the backlight module;

FIG. 3 is a thin film interference pattern generated by the backlight module of FIG. 2;

fig. 4 is a schematic structural diagram of a backlight module according to an embodiment of the present application;

FIG. 5 is a side view of a diffusion membrane provided in accordance with one embodiment of the present application;

FIG. 6 is a front view of a diffusion membrane according to an embodiment of the present disclosure;

FIG. 7 is a front view of another diffusion membrane provided in accordance with an embodiment of the present application;

fig. 8 is a schematic structural diagram of a light guide plate according to a first embodiment of the present application.

Description of reference numerals:

1-an underscreen fingerprint identification device; 11-fingerprint identification module; 111-an optical path guiding structure; 112-a fingerprint sensor; 12-a detection light source; 2-liquid crystal display screen; 21-a display module; 211-transparent protective cover plate; 212-liquid crystal panel; 22-a backlight module; 221-a brightness enhancement film; 2211-brightening particles; 222-a diffusion membrane; 2221. 2221a, 2221b, 2221 c-microstructure; 223-a light guide plate; 2231-a light guide bar; 2232-light-conducting particles; 224-a reflective film; 225-a back plate; 3-Newton's ring.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Example one

FIG. 1 is a schematic diagram of an underscreen fingerprint identification system; FIG. 2 is a schematic view of a local deformation of the backlight module; FIG. 3 is a thin film interference pattern generated by the backlight module of FIG. 2; fig. 4 is a schematic structural diagram of a backlight module according to an embodiment of the present application; FIG. 5 is a side view of a diffusion membrane provided in accordance with one embodiment of the present application; FIG. 6 is a front view of a diffusion membrane according to an embodiment of the present disclosure; FIG. 7 is a front view of another diffusion membrane provided in accordance with an embodiment of the present application; fig. 8 is a schematic structural diagram of a light guide plate according to a first embodiment of the present application.

As shown in fig. 1, the present embodiment provides an off-screen fingerprint identification device 1, which is suitable for an electronic apparatus having a liquid crystal display 2, and the fingerprint detection area of the off-screen fingerprint identification device 1 is at least partially located in the display area of the liquid crystal display 2. Specifically, the fingerprint identification device 1 under the screen that this embodiment provided can be applicable to Liquid Crystal Display (LCD)2, and this fingerprint identification device 1 is optical fingerprint identification device under the screen, can use on smart mobile phone, panel computer and other adopt liquid crystal display 2's mobile terminal or electronic equipment.

More specifically, in the above-mentioned mobile terminal or electronic device, the underscreen fingerprint identification apparatus 1 may be disposed in a local area below the liquid crystal display 2, and cooperate with the liquid crystal display 2 to form an underscreen fingerprint identification system. Wherein, the fingerprint detection area of the under-screen fingerprint identification device 1 can be specifically positioned in at least a part of the display area of the liquid crystal display screen 2. For example, by placing a finger above a corresponding fingerprint detection area in the display area of the liquid crystal display 2, the off-screen fingerprint recognition apparatus 1 acquires and recognizes a fingerprint image of the finger.

As shown in fig. 1, the lcd 2 generally includes a liquid crystal panel 212 and a backlight module 22, and the backlight module 22 is disposed below the liquid crystal panel 212 and is used for providing a backlight source for the liquid crystal panel 212, so that the liquid crystal panel 212 displays a picture for a user to watch.

Specifically, fingerprint identification device 1 can be including the fingerprint identification module 11 that is located liquid crystal display 2's backlight unit 22 below under the screen, and fingerprint identification module 11 is used for receiving the fingerprint reflection formation and the fingerprint detection light that sees through liquid crystal display 2 through the fingerprint detection area top to acquire the fingerprint image of finger.

As shown in fig. 1, the off-screen fingerprint identification device 1 includes a fingerprint identification module 11, the fingerprint identification module 11 may include a fingerprint sensor 112, the fingerprint sensor 112 may be an optical fingerprint sensor 112, and the fingerprint sensor 112 may include an optical sensing array having a plurality of sensing units, and a reading circuit electrically connected to the optical sensing array and other auxiliary circuits. The sensing area of the optically sensitive array may correspond to a fingerprint recognition area of the fingerprint sensor 112.

Wherein, fingerprint sensor 112 can be located liquid crystal display 2's fingerprint detection area below, for example, fingerprint sensor 112 is located liquid crystal display 2's fingerprint detection area just right backlight unit 22 below, through placing the finger in liquid crystal display 2's fingerprint detection area top, the fingerprint detection light that carries fingerprint information that the finger reflection formed sees through backlight unit 22 and transmits to fingerprint sensor 112, through fingerprint sensor 112's fingerprint identification regional acquisition and discernment fingerprint image.

In addition, because the fingerprint detection region that fingerprint identification device 1 corresponds under the screen can be located among liquid crystal display 2's display area, when the user need carry out fingerprint unblock or other fingerprint verification to mobile terminal or electronic equipment that adopt above-mentioned fingerprint identification device 1 under the screen, it only need press the fingerprint detection region alright in this liquid crystal display 2 with the finger and realize fingerprint input, consequently, this liquid crystal display 2's display area can expand to the front that covers whole mobile terminal or electronic equipment, satisfy the comprehensive screen demand of high screen occupation ratio.

In one possible embodiment, the optical sensing array of the fingerprint sensor 112 and other circuits may be fabricated on a chip (Die) by a semiconductor process, wherein the optical sensing array is specifically a photo detector (photo detector) array, which includes a plurality of photo detectors distributed in an array, and the photo detectors may be used as optical sensing units.

In addition, the fingerprint identification module 11 may further include a light path guiding structure 111 and other optical components, and the light path guiding structure 111 and other optical components may be disposed below the fingerprint detection area of the liquid crystal display screen 2; the light path guiding structure 111 is mainly used for guiding the fingerprint detection light generated when a finger is pressed on the fingerprint detection area and transmitted through the liquid crystal display screen 2 to the optical sensing array of the fingerprint sensor 112 for optical detection; the other optical components may include a Filter layer (Filter), which may be disposed between the optical path guiding structure 111 and the fingerprint sensor 112, and is used to Filter the interference light passing through the optical path guiding structure 111, so as to prevent the interference light from being received by the optical sensor array to affect the fingerprint recognition effect.

In the device 1 for identifying fingerprints under a screen provided in this embodiment, the fingerprint sensor 112, the light path guiding structure 111 and the filter layer may be packaged in the same optical component to form the fingerprint identification module 11.

The optical path directing structure 111 may take a variety of embodiments. In one possible embodiment, the optical path directing structure 111 may be an optical Lens (Lens) layer having one or more Lens units, such as a Lens group consisting of one or more aspheric lenses. The optical lens layer may be used to condense the fingerprint detection light formed from the finger and transmitted through the liquid crystal display 2 to the optical sensing array of the fingerprint sensor 112 therebelow, so that the optical sensing array may perform optical imaging based on the fingerprint detection light, thereby obtaining a fingerprint image of the finger.

Optionally, the optical lens layer may further be formed with a pinhole or an aperture stop in the optical path of the one or more lens units, and the pinhole or the aperture stop may cooperate with the optical lens layer to enlarge a field of View (FOV) of the underscreen fingerprint identification apparatus 1, so as to improve the fingerprint imaging effect of the underscreen fingerprint identification apparatus.

In another possible embodiment, the optical path guiding structure 111 may be a Collimator (collimater) layer fabricated on a semiconductor silicon chip or other substrate, and has a plurality of collimating units, which may be collimating through holes with a certain aspect ratio; the user carries out fingerprint identification at liquid crystal display 2 when, in the fingerprint detection light that the finger of 2 tops of liquid crystal display formed and see through liquid crystal display 2, the fingerprint detection light that incident angle and the extending direction of this collimation unit are unanimous basically can pass the collimation unit and be received by the induction element of its below, and the fingerprint detection light that the incident angle degree is too big is attenuated by multiple reflection in this collimation unit is inside, consequently, each induction element can only receive the fingerprint detection light that the fingerprint line that its is directly over formed basically, thereby make the fingerprint detection light that the optical induction array utilized each detection element to detect respectively obtain the fingerprint image of finger.

In other embodiments, the optical path guiding structure 111 may further specifically include a Micro-Lens (Micro-Lens) layer and an optical film layer, the Micro-Lens layer includes a Micro-Lens array formed by a plurality of Micro-lenses, which may be formed on the optical sensing array of the fingerprint sensor 112 through a semiconductor growth process or other processes, and each Micro-Lens may correspond to one or more sensing units of the optical sensing array, respectively. An optical film layer may be formed between the microlens layer and the optical sensing unit, and may include at least one light blocking layer having micro-holes, and a dielectric layer, a passivation layer, or a buffer layer, etc., formed between the light blocking layer and the microlens layer and the optical sensing array, wherein the at least one light blocking layer having micro-holes employs a specific optical design to form micro-holes between its corresponding microlens and the sensing unit, thereby defining a receiving optical path of the sensing unit.

The light blocking layer can block optical interference between adjacent micro lenses and the sensing unit, and the micro lenses converge received light rays into the micro holes at a specific vertical or inclined angle and transmit the light rays to the sensing unit through the micro holes for optical fingerprint imaging.

It is understood that, in practical applications, the liquid crystal display panel 2 may further include a transparent protective cover 211, such as a glass cover or a sapphire cover, which is specifically located above the liquid crystal panel 212 of the liquid crystal display panel 2 and covers the front surface of the liquid crystal panel 212. Therefore, in the present embodiment, the pressing of the finger on the liquid crystal display 2 may specifically be pressing the transparent protective cover 211 above the liquid crystal panel 212 or a protective layer (such as a tempered film or other protective film) covering the surface of the transparent protective cover 211.

In a possible embodiment, the device 1 may further include a detection light source 12, where the detection light source 12 is configured to emit detection light, and the detection light is irradiated to a finger above the fingerprint identification area through the liquid crystal display 2, and forms fingerprint detection light carrying fingerprint information through reflection of the finger.

As shown in fig. 1, in this embodiment, fingerprint identification device 1 is including fingerprint identification module 11 under the screen, still including detecting light source 12, detecting light source 12 transmission detecting light, detecting light can shine the finger above the fingerprint monitoring area through liquid crystal display 2, detecting light shines to the finger after by finger reflection formation fingerprint detection light, the fingerprint identification module 11 of fingerprint detection light transmission to backlight unit 22 below of formation is seen through liquid crystal display 2, the fingerprint detection light that carries fingerprint information forms the fingerprint image on fingerprint sensor 112, carry out fingerprint identification through fingerprint sensor 112.

In order to avoid the mutual influence between the fingerprint detection light and the backlight provided by the backlight module 22, as shown in fig. 1, in one possible embodiment, the wavelength of the detection light and the backlight provided by the backlight module 22 for displaying the image may be different. In practical applications, the backlight module 22 may include a backlight source, and the backlight source provides backlight for illuminating the liquid crystal display panel 2, so that the liquid crystal display panel 2 displays images through the backlight provided by the backlight module 22.

In this embodiment, the wavelength of the detection light emitted by the detection light source 12 of the underscreen fingerprint identification device 1 is different from the wavelength of the backlight provided by the backlight module 22, so that the mutual influence between the detection light and the backlight can be avoided, and the backlight emitted by the backlight source of the backlight module 22 can be completely used for illuminating the screen, so as to ensure the brightness of the liquid crystal display screen 2; and the probe light that light source 12 sent then mainly is used for shining the finger to fingerprint detection area top to make the finger to the sufficient light of fingerprint identification module 11 reflection, and then can ensure that fingerprint sensor 112 acquires the better fingerprint image of definition.

In one embodiment, the detection light may be infrared light, and the backlight provided by the backlight module 22 may be visible light. In this embodiment, the underscreen fingerprint identification apparatus 1 may use a non-visible light source with a specific wavelength as a fingerprint excitation light source to realize optical fingerprint identification, for example, the detection light emitted by the detection light source 12 may be infrared light, that is, the detection light source 12 is an infrared light source, and exemplarily, the infrared light source may be an infrared LED light source, an infrared Vertical Cavity Surface Emitting Laser (VCSEL) or an infrared Laser Diode (Laser Diode).

The infrared light that detection light source 12 sent can see through liquid crystal display panel 212 or transparent protection apron 211 shines the finger to liquid crystal display 2's fingerprint detection area top, and the infrared light can take place the transmission on the finger surface or form infrared fingerprint detection light from the transmission of finger surface, this infrared fingerprint detection light carries the fingerprint information of finger, it can see through liquid crystal display 2's liquid crystal display panel 212 and backlight unit 22, and transmit fingerprint identification module 11 to backlight unit 22 below, fingerprint identification module 11 leads fingerprint detection light guide to fingerprint sensor 112's optical induction array through light path guide structure 111, optical induction array can accept fingerprint detection light and further obtains the fingerprint information of finger according to fingerprint detection light.

The backlight provided by the backlight source in the backlight module 22 may be visible light, and the liquid crystal display screen 2 is illuminated by the visible light, so that the liquid crystal display screen 2 displays a picture; in this way, the detection light source 12 of the underscreen fingerprint identification device 1 is infrared light, and the infrared light is different from the backlight visible light, so as to avoid the mutual influence between the detection light source 12 and the backlight source, so that the visible light emitted by the backlight source is all used for illuminating the liquid crystal display screen 2, and the infrared light emitted by the detection light source 12 is all used for illuminating the finger to form fingerprint detection light.

In this embodiment, the backlight module 22 of the liquid crystal display 2 may include a diffusion film 222 and a light guide plate 223 adjacently disposed below the diffusion film 222, a surface of the diffusion film 222 facing the light guide plate 223 has a plurality of microstructures 2221 distributed at intervals, and the microstructures 2221 are used to increase a distance between the diffusion film 222 and the light guide plate 223, so as to prevent a film interference phenomenon when fingerprint detection light passes through between the diffusion film 222 and the light guide plate 223.

Since the fingerprint detection light reflected by the finger needs to be transmitted to the fingerprint identification module 11 through the backlight module 22, the backlight module 22 at least includes the diffusion film 222 and the light guide plate 223 stacked in sequence below the liquid crystal panel 212, the light guide plate 223 can be adjacently disposed below the diffusion film 222, for the lateral backlight module 22, the backlight is usually disposed at the side of the light guide plate 223, the light guide plate 223 is used for converting the line light source emitted by the backlight into the surface light source and emitting the surface light source to the liquid crystal panel 212 above the backlight module 22, and the diffusion film 222 is used for further homogenizing the surface light source passing through the light guide plate 223 to form a uniform surface light source.

It should be understood that the backlight module 22 includes other optical films stacked above the diffusion film 222 or below the light guide plate 223, in addition to the diffusion film 222 and the light guide plate 223, and the description thereof is omitted. A back plate 225 is generally disposed under the light guide plate 223, the back plate 225 is used for supporting the optical film in the backlight module 22, and the fingerprint identification module 11 may be disposed under the back plate 225. The back plate 225 may be generally supported by a metal material having high strength and high rigidity, for example, the back plate 225 may be a steel plate, and a through hole is formed in a portion of the back plate 225 corresponding to the fingerprint identification module 11, so that the fingerprint detection light reflected by a finger passes through the through hole in the back plate 225 to irradiate the fingerprint identification module 11 after passing through each layer of optical film, and the fingerprint detection light can be received by the fingerprint identification module 11.

As shown in fig. 2 and fig. 3, an air gap inevitably exists between the optical films stacked on top of each other, and particularly, in the area of the optical film corresponding to the through hole of the back plate 225, because the area is not supported by the back plate 225, and the gravity of the optical film itself is added, in the area corresponding to the through hole of the back plate 225, each optical film has a phenomenon that each optical film is recessed to the through hole of the back plate 225 to a different degree, which may result in an uneven air gap being formed between the optical films of each layer, and the uneven air gap may cause an optical path difference in light propagation.

Because the fingerprint detection region is located directly over this region, therefore the fingerprint detection light of the finger reflection of fingerprint detection region top can pass through each layer optical film that this region corresponds, when the fingerprint detection light passes through the inhomogeneous air gap between each layer optical film, can produce film interference phenomenon between the fingerprint detection light of optical film transmission and reflection, and then can make the fingerprint detection light form "newton ring 3", this can make the image formation clear "newton ring 3" that fingerprint sensor 112 received, newton ring 3 "can cover the fingerprint image even, and then can reduce the definition of the fingerprint image that fingerprint sensor 112 received, fingerprint sensor 112 can't receive effectual fingerprint image even, this can seriously disturb the fingerprint formation of image, lead to fingerprint sensor 112 can't effectively receive and discern the fingerprint image.

In order to obtain clear fingerprint image for fingerprint sensor 112, so as to ensure that fingerprint sensor 112 can effectively identify the fingerprint image, avoid the fingerprint to detect the light and produce the film interference phenomenon in the process of seeing through backlight unit 22, avoid producing "newton ring 3" between each optics diaphragm, in this embodiment, through changing the air gap between each optics diaphragm in backlight unit 22, solve the problem of the film interference that the fingerprint detects the light and produces when seeing through backlight unit 22.

In particular, as shown in fig. 4 to 7, for the non-uniform air gap generated between the diffusion film 222 and the light guide plate 223 in the backlight assembly 22 in the region corresponding to the through-hole of the back plate 225, by providing a plurality of microstructures 2221 on the surface of the diffusion film 222 on the side facing the light guide plate 223, the plurality of microstructures 2221 are distributed at intervals on the surface of the diffusion film 222, by thus supporting a plurality of microstructures 2221 between diffusion film 222 and light guide plate 223, microstructures 2221 can increase the gap between diffusion film 222 and light guide plate 223, thereby increasing the air gap between the diffusion film 222 and the light guide plate 223, preventing the fingerprint detection light from generating a thin film interference phenomenon when passing between the diffusion film 222 and the light guide plate 223, and further, it is possible to reduce or even prevent the fingerprint detection light from forming "newton's ring 3" on the fingerprint sensor 112, so as to ensure the fingerprint imaging effect and enable the fingerprint sensor 112 to acquire a clear fingerprint image.

It can be understood that the plurality of microstructures 2221 are spaced apart from each other and cover the entire surface of the diffusion film 222, so that the air gap between the diffusion film 222 and the light guide plate 223 can be increased as a whole, the uniformity of the gap between different portions of the diffusion film 222 and the light guide plate 223 can be improved, and a uniform air gap can be formed between the diffusion film 222 and the light guide plate 223, thereby better eliminating the thin film interference phenomenon generated between the diffusion film 222 and the light guide plate 223.

As shown in fig. 5, in one possible embodiment, the microstructures 2221 of the surface of the diffusion film 222 facing the light guide plate 223 may be convex structures formed on the surface of the diffusion film 222. Specifically, the microstructures 2221 on the surface of the diffusion film 222 are protruding structures protruding from the light guide plate 223, the protruding structures are supported between the diffusion film 222 and the light guide plate 223, the top ends of the protruding structures abut against the light guide plate 223, and the height of the protruding structures is the gap between the diffusion film 222 and the light guide plate 223.

Specifically, as shown in fig. 5, microstructures 2221 may be hemispherical convex structures. By arranging the microstructures 2221 as hemispherical protruding structures, the microstructures 2221 protrude from the surface of the diffusion film 222 in a hemispherical structure, so that the contact area between the microstructures 2221 and the diffusion film 222 is large, the microstructures 2221 can be formed on the surface of the diffusion film 222 conveniently, and the connection strength between the microstructures 2221 and the diffusion film 222 is large; in addition, the spherical top of microstructure 2221 contacts light guide plate 223, microstructure 2221 and light guide plate 223 are point contacts, which has a small influence on the light guiding performance of light guide plate 223, and the gap between adjacent microstructures 2221 is large, which can ensure that a large air gap exists between diffusion film 222 and light guide plate 223, wherein the height of the hemispherical surface is the distance between diffusion film 222 and light guide plate 223.

In one embodiment, the diameter of microstructures 2221 may be between 120-170 μm and the height of microstructures 2221 may be between 1-3 μm. By setting the diameter of microstructure 2221 between 120 and 170 μm, the hemispherical protrusion serving as microstructure 2221 has a larger volume, and the height of the hemispherical protrusion is controlled to be between 1-3 μm, so that the contact area between the hemispherical protrusion and the diffusion film 222 is large, and the surface of the hemispherical protrusion is smooth, thereby ensuring that the microstructure 2221 can increase the distance between the diffusion film 222 and the light guide plate 223, and avoiding that the surface of the hemispherical protrusion serving as microstructure 2221 is too steep, and when the hemispherical protrusion with a steep surface is in contact with the light guide plate 223, the surface of the light guide plate 223 can be scratched or damaged, thereby affecting the light guiding effect of the light guide plate 223.

By controlling the height of microstructures 2221 to be between 1-3 μm, for example, the height of microstructures 2221 is 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, preferably, the height of microstructures 2221 may be 2.3 μm, so that the gap between diffusion film 222 and light guide plate 223 can effectively solve the problem of thin film interference between diffusion film 222 and light guide plate 223; meanwhile, the height of the microstructure 2221 is in a suitable range, and the diameter of the microstructure 2221 is controlled in a larger radius range between 120 μm and 170 μm, for example, the diameter of the microstructure 2221 may be 130 μm, 138 μm, 142 μm, 153 μm or 160 μm, and preferably, the diameter of the microstructure 2221 may be 150 μm, so that the microstructure 2221 may form a gentle hemispherical protrusion, and thus the microstructure 2221 may not have a great influence on the light uniformity of the diffusion film 222 and may not affect the display effect of the liquid crystal display panel 2.

In the embodiment, the microstructure 2221 on the surface of the diffusion film 222 is set to be the hemispherical convex structure with the diameter of 120-170 μm and the height of 1-3 μm, so that the gap between the diffusion film 222 and the light guide plate 223 is increased, the thin film interference phenomenon between the diffusion film 222 and the light guide plate 223 is effectively solved, and the fingerprint imaging effect is improved; meanwhile, the microstructures 2221 are smooth hemispherical protruding structures, which will not affect the light-uniformizing effect of the diffusion film 222, and will not damage the surface of the light guide plate 223.

As shown in fig. 6 and 7, in one possible embodiment, a plurality of microstructures 2221 may be uniformly spaced on the surface of diffusion film 222. As described above, in this embodiment, the microstructures 2221 on the surface of the diffusion film 222 are hemispherical protruding structures with large volumes and smooth surfaces, and the microstructures 2221 are in contact with the light guide plate 223, so that the microstructures 2221 can be uniformly arranged on the surface of the diffusion film 222 at intervals, and thus the microstructures 2221 are uniformly distributed in each area of the diffusion film 222, gaps between the diffusion film 222 and each area of the light guide plate 223 are uniform, and the microstructures 2221 have a good supporting effect on the diffusion film 222 and the light guide plate 223, so that the microstructures 2221 can be improved to improve the effect of improving the film interference between the diffusion film 222 and the light guide plate 223.

In addition, since the microstructures 2221 are uniformly distributed, the microstructures 2221 can be conveniently formed on the surface of the diffusion film 222, and the flatness of the diffusion film 222 and the light guide plate 223 can be improved, so that the optical effects of the diffusion film 222 and the light guide plate 223 can be improved.

In the case where the plurality of microstructures 2221 are uniformly spaced on the surface of the diffusion film 222, as shown in fig. 6, in one possible embodiment, the plurality of microstructures 2221 may be uniformly spaced along the length direction and the width direction of the diffusion film 222. By arranging the microstructures 2221 in the length direction and the width direction of the diffusion film 222, a plurality of microstructures 2221 may be formed in a row arrangement form parallel to the length direction of the diffusion film 222 and a column arrangement form parallel to the width direction of the diffusion film 222, and a plurality of rows and columns of microstructures 2221 are interlaced to form a uniformly distributed rectangular distribution form.

Specifically, the pitch between every two adjacent rows of microstructures 2221 and the pitch between every two adjacent columns of microstructures 2221 may be equal. In this embodiment, the pitch between two adjacent rows of microstructures 2221 is equal to the pitch between two adjacent columns of microstructures 2221, that is, the row pitch and the column pitch of the microstructures 2221 in the rectangular distribution form are equal, so that the pitch between adjacent microstructures 2221 in each row is equal to the pitch between adjacent microstructures 2221 in two adjacent rows, and a square structure is formed between four adjacent microstructures 2221 in two adjacent rows.

As shown in fig. 7, in another possible embodiment, a plurality of microstructures 2221 may be uniformly spaced along the length direction of the diffusion film 222, the pitch between every two adjacent rows of microstructures 2221 is equal, and the microstructures 2221 between two adjacent rows are staggered from each other.

In addition to the plurality of microstructures 2221 arranged in the longitudinal direction and the width direction of the diffusion film 222 to form rows, columns and rows, the microstructures 2221 may also be arranged at regular intervals in the longitudinal direction of the diffusion film 222, with the pitch between two adjacent rows being equal, but the microstructures 2221 between two adjacent rows being staggered. Thus, the microstructures 2221 are arranged in rows, the pitch between adjacent microstructures 2221 in each row is equal, and the row pitch between adjacent rows is equal, so that the microstructures 2221 can still form a structure uniformly arrayed on the surface of the diffusion film 222, but the microstructures 2221 in adjacent rows are staggered, that is, the adjacent microstructures 2221 in adjacent rows are not on the same column.

Specifically, microstructures 2221 can be equidistant from two microstructures 2221 in adjacent rows that are offset from one another. As shown in fig. 7, taking a certain microstructure 2221a in a certain row as an example, two microstructures 2221 adjacent to the microstructure 2221a in adjacent rows are respectively a microstructure 2221b located at the left side of the microstructure 2221 and a microstructure 2221c located at the right side of the microstructure 2221a, and by making the pitches between the microstructure 2221a and the two

microstructures

2221b and 2221c in adjacent rows equal, the projection of the microstructure 2221a in its adjacent row is located at the midpoint of the connecting line between the

microstructures

2221b and 2221 c. In this way, in each three rows of microstructures 2221, a diamond-shaped structure may be formed between two adjacent microstructures 2221 in the middle row and two microstructures 2221 in the two rows on both sides that are located on the perpendicular bisector of the line connecting the two microstructures 2221 in the middle row. For example, microstructure 2221a, microstructure 2221b, microstructure 2221c, and microstructure 2221d form separate structures.

In one embodiment, the spacing between two adjacent microstructures 2221 in two adjacent rows may be equal to the spacing between two adjacent microstructures 2221 in the same row. By making the pitch between two adjacent microstructures 2221 in two adjacent rows equal to the pitch between two adjacent microstructures 2221 in the same row, for example, the pitch between

microstructure

2221a and 2221b is equal to the pitch between

microstructure

2221b and 2221c, so that the pitches between

microstructure

2221a and 2221b,

microstructure

2221b and 2221c, and

microstructure

2221a and 2221c are equal, regular triangular structures are formed between three adjacent microstructures 2221 in two adjacent rows, and the distribution of microstructures 2221 on the surface of diffusion film 222 is more uniform.

Whether the plurality of microstructures 2221 are distributed on the surface of the diffusion film 222 in a rectangular shape as a whole or in a diamond shape as a whole, the pitch between two adjacent rows of microstructures 2221 can be between 200 μm and 450 μm. By setting the line pitch of the microstructures 2221 to be between 200 and 450 μm, so that the pitch of the microstructures 2221 is relatively matched with the structure of the surface of the light guide plate 223, the pitch between the diffusion film 222 and the light guide plate 223 can be controlled within a suitable range, and the microstructures 2221 have relatively moderate density on the surface of the diffusion film 222, and have no significant influence on the even light diffusion effect. For example, the pitch between two adjacent rows of microstructures 2221 can be 250 μm, 300 μm, 350 μm, 400 μm, or 450 μm.

Wherein, for the structure form that the microstructures 2221 are arranged in rows and columns to form a rectangular distribution as a whole, preferably, the distance between two adjacent rows of microstructures 2221 is equal to the distance between two adjacent microstructures 2221 in the same row, and may be 320 μm; for the structure form that the microstructures 2221 are arranged in rows and adjacent rows are staggered to form a rhombus distribution as a whole, it is preferable that the pitch between two adjacent rows of microstructures 2221 is 320 μm and the pitch between two adjacent microstructures 2221 in the same row is 370 μm, so that the connecting lines between three adjacent microstructures 2221 in two adjacent rows form a regular triangle.

As shown in fig. 8, in one possible embodiment, a surface of the light guide plate 223 facing the diffusion film 222 may have a plurality of convex light guide bars 2231, the light guide bars 2231 may extend in a width direction of the light guide plate 223, and the plurality of light guide bars 2231 may be uniformly spaced in a length direction of the light guide plate 223.

In this embodiment, the surface of the light guide plate 223 facing the diffusion film 222 has a plurality of convex light guide strips 2231, and the light guide strips 2231 can enhance the light guiding effect of the light guide plate 223, so that the backlight emitted from the backlight source located at one side of the light guide plate 223 can be better transmitted to the other side of the light guide plate 223, and the surface light source emitted from the front surface of the light guide plate 223 has more uniform brightness.

Specifically, the light guide strips 2231 extend in the width direction of the light guide plate 223, and the plurality of light guide strips 2231 are arranged at intervals in the length direction of the light guide plate 223, so that the light guiding effect of the light guide strips 2231 can be enhanced, and the backlight emitted by the backlight source sequentially passes through different light guide strips 2231 to the other side of the light guide plate 223. In addition, a plurality of light guide strips 2231 and microstructures 2221 of diffusion film 222 are supported between diffusion film 222 and light guide plate 223, so that the distance between diffusion film 222 and light guide plate 223 can be further increased, and the problem of film interference between diffusion film 222 and light guide plate 223 is effectively solved.

It should be noted that, as described above, in this embodiment, by setting microstructures 2221 on the surface of diffusion film 222 to be uniformly spaced, microstructures 2221 can better correspond to light guide strips 2231, and a plurality of microstructures 2221 contact different portions of different light guide strips 2231, so that the gap between diffusion film 222 and light guide plate 223 is uniform as a whole, and the distance between diffusion film 222 and light guide plate 223 is determined by microstructures 2221 and light guide strips 2231.

As shown in fig. 8, alternatively, the light guide strip 2231 may extend from one side to the other side in the width direction of the light guide plate 223. Extend to the opposite side by the width direction's of light guide plate 223 one side through light guide bar 2231, the light of each position and each angle of incidence to light guide plate 223 all can transmit to light guide bar 2231, and light guide bar 2231 all can lead light to it, can promote light guide bar 2231's leaded light effect like this.

Specifically, the cross section of the light guide bar 2231 may be a circular arc. As shown in fig. 8, the cross section of the light guide strip 2231 is configured to be circular arc, on one hand, the circular arc light guide strip 2231 has a certain light condensing effect, so that the light guide effect of the light guide plate 223 is enhanced, and at the same time, the brightness of the light emitted from the light guide plate 223 can be increased by the light guide strip 2231, so as to enhance the display effect of the liquid crystal display 2.

On the other hand, by setting light guide bar 2231 in a circular arc column shape, since microstructures 2221 of diffusion film 222 are hemispherical protrusions, light guide bar 2231 and microstructures 2221 are in a circular arc contact form and are in smooth contact with each other, and thus light guide bar 2231 and microstructures 2221 are not damaged, and the strength of both can be improved.

More importantly, as shown in fig. 8, when microstructures 2221 of diffusion film 222 and light guide bar 2231 are in contact, the top of microstructures 2221 may be in contact with the top of light guide bar 2231, or other parts of the spherical surface of microstructures 2221 may be in contact with other parts of light guide bar 2231, and no matter which part of microstructures 2221 and light guide bar 2231 is in contact, a large gap may be ensured between diffusion film 222 and light guide plate 223, so as to effectively avoid the film interference phenomenon between diffusion film 222 and light guide plate 223.

In one embodiment, the radius of curvature of the cross-section of the light guide 2231 can be between 30-150 μm and the height of the light guide 2231 can be between 1-5 μm. By controlling the radius of curvature of the cross section of the light guide strip 2231 to be 30-150 μm and controlling the height of the light guide strip 2231 to be 1-5 μm, the light guide strip 2231 forms a relatively gentle arc columnar structure on the surface of the light guide plate 223, and the light guide strip 2231 can improve the light guide effect of the light guide plate 223, and at the same time, the light guide strip 2231 has good stability when contacting the microstructures 2221 of the diffusion film 222. For example, the radius of curvature of the cross section of the light guide bar 2231 may be 30 μm, 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, or the like, and preferably, the radius of curvature of the cross section of the light guide bar 2231 is 40 μm.

The height of the light guide strip 2231 is set to be 1-5 μm, and the overall height of the light guide strip 2231 and the microstructures 2221 of the diffusion film 222 can be greater than 5 μm, so that the condition of avoiding the occurrence of the film interference phenomenon between the diffusion film 222 and the light guide plate 223 can be completely met, and the problem of the generation of the newton ring 3 between the diffusion film 222 and the light guide plate 223 can be effectively solved, so as to ensure the fingerprint imaging effect. Illustratively, the height of the light guide bar 2231 may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, and preferably, the height of the light guide bar 2231 may be 3 μm.

Alternatively, the spacing between the centerlines of two adjacent light guide bars 2231 may be between 40-150 μm. By controlling the distance between the center lines of two adjacent light guide bars 2231 to be between 40 and 150 μm, and combining the curvature radius of the cross section of the light guide bars 2231 and the height of the light guide bars 2231, a suitable interval can be provided between the light guide bars 2231, and the light guide bars 2231 can cover the whole light guide plate 223, so as to improve the light guide effect of the light guide bars 2231; moreover, the degree of correspondence between light guide strip 2231 and microstructures 2221 of diffuser film 222 is good, and the gap between light guide plate 223 and diffuser film 222 can be controlled well. For example, the distance between the center lines of two adjacent light guide bars 2231 may be 50 μm, 70 μm, 90 μm, 110 μm, or 130 μm, and preferably, the distance between the center lines of two adjacent light guide bars 2231 may be 80 μm.

As shown in fig. 8, in one possible embodiment, a surface of the light guide plate 223 facing away from the diffusion film 222 may have a plurality of light guide particles 2232 distributed at intervals, and the light guide particles 2232 are supported between the light guide plate 223 and the reflective film 224 of the backlight module 22.

In the backlight module 22, a reflective film 224 is further disposed below the light guide plate 223, the reflective film 224 is located between the light guide plate 223 and the back plate 225, and the reflective film 224 is used for reflecting all the light emitted from the backlight to the light guide plate 223 so that the light guide plate 223 emits all the light from the front surface thereof. A plurality of light guide particles 2232 are formed on a surface of the light guide plate 223 facing away from the diffusion film 222, that is, a surface of the light guide plate 223 facing the reflective film 224, the plurality of light guide particles 2232 are distributed on the surface of the light guide plate 223 at intervals, and when light emitted from the backlight strikes each light guide particle 2232, the light guide particles 2232 diffuse the reflected light to various angles, and then the reflective condition is destroyed to be emitted from the front surface of the light guide plate 223. The light guide plate 223 can uniformly emit light through the light guide particles 2232 at different positions.

In addition, the light guide particles 2232 are supported between the light guide plate 223 and the reflective film 224, and by setting a reasonable size of the light guide particles 2232, a gap between the light guide plate 223 and the reflective film 224 can be controlled within a reasonable range to eliminate a thin film interference phenomenon between the light guide plate 223 and the reflective film 224.

It can be understood that the light guide strip 2231 and the light guide particles 2232 may be made of the same material as the light guide plate 223, and the light guide strip 2231 and the light guide particles 2232 may be formed on the surface of the light guide plate 223 by etching or the like, so that the light guide plate 223, the light guide strip 2231, and the light guide particles 2232 are integrally formed.

In particular, the height of light-guiding particles 2232 may be between 3-5 μm. By setting the height of the light guide particles 2232 to 3 to 5 μm, the distance between the light guide plate 223 and the reflective film 224 can be controlled to 3 to 5 μm, which can effectively solve the problem of thin film interference between the light guide plate 223 and the reflective film 224, avoid the generation of "newton ring 3" when fingerprint detection light passes between the light guide plate 223 and the reflective film 224, and improve the fingerprint imaging effect. Illustratively, the height of the light-guiding particles 2232 may be 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm, and preferably, the height of the light-guiding particles 2232 may be 4.6 μm.

In one embodiment, the density of light directing particles 2232 may be different at different regions of the surface of light directing plate 223 facing away from diffuser film 222. In this embodiment, the light guiding particles 2232 may be non-uniformly distributed on the surface of the light guiding plate 223 facing the reflective film 224, wherein the backlight of the backlight module 22 is disposed on one side of the light guiding plate 223, so that the light beam at the portion of the light guiding plate 223 closer to the backlight is stronger, and the light beam at the portion farther from the backlight is weaker, so that the density of the light guiding particles 2232 at the portion of the light guiding plate 223 closer to the backlight may be smaller than the density of the light guiding particles 2232 at the portion farther from the backlight, so that the light guiding particles 2232 with different densities may make the light intensity of each portion of the light guiding plate 223 more uniform.

As shown in fig. 4, in one possible embodiment, the backlight module 22 may further include a brightness enhancement film 221 disposed adjacent to and above the diffuser film 222, and the surface of the brightness enhancement film 221 facing the diffuser film 222 may have a plurality of brightness enhancement particles 2211 distributed at intervals. The backlight module 22 further includes a brightness enhancement film 221, the brightness enhancement film 221 is adjacently disposed above the diffuser film 222, the brightness enhancement film 221 is used for enhancing the brightness of the light, the diffuser film 222 homogenizes the light and emits the homogenized light to the brightness enhancement film 221, and the brightness of the light is further increased through the brightness enhancement film 221, so as to enhance the brightness of the liquid crystal display 2.

In this embodiment, a plurality of brightness enhancement particles 2211 are formed on the surface of the brightness enhancement film 221 facing the diffuser 222, the brightness enhancement particles 2211 are distributed at intervals, and the brightness enhancement particles 2211 are supported between the brightness enhancement film 221 and the diffuser 222 to increase the gap between the brightness enhancement film 221 and the diffuser 222, so as to avoid the film interference phenomenon when fingerprint detection light passes through the gap between the brightness enhancement film 221 and the diffuser 222, and improve the fingerprint imaging effect.

In particular, as shown in FIG. 4, the brightness enhancing particles 2211 may be microsphere structures embedded in the brightness enhancing film 221, with the diameter of the brightness enhancing particles 2211 being between 4-10 μm. By arranging the brightness enhancement particles 2211 in a microsphere structure, the brightness of the liquid crystal display screen 2 can be further enhanced by the brightness enhancement particles 2211. Also, by controlling the diameter of the brightness enhancing particles 2211 to be between 4-10 μm, the height of the brightness enhancing particles 2211 exposed at the surface of the brightness enhancing film 221 can still ensure that no thin film interference occurs between the brightness enhancing film 221 and the diffuser film 222, based on the fact that there is a portion of brightness enhancing particles 2211 embedded in the brightness enhancing film 221.

Illustratively, the diameter of the brightness enhancing particles 2211 may be 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, and preferably, the diameter of the brightness enhancing particles 2211 may be 5 μm.

In one embodiment, the brightness enhancing particles 2211 can be uniformly distributed across the surface of the brightness enhancing film 221. In this embodiment, the main function of the brightness enhancement particles 2211 is to increase the gap between the brightness enhancement film 221 and the diffuser film 222, and since the diameter of the brightness enhancement particles 2211 is small, the brightness enhancement particles 2211 may be formed on the surface of the brightness enhancement film 221 by etching or printing, and the brightness enhancement particles 2211 may be randomly distributed on the surface of the brightness enhancement film 221, so that the smaller and denser brightness enhancement particles 2211 are uniform on the surface of the brightness enhancement film 221.

The under-screen fingerprint identification device provided by the embodiment is suitable for electronic equipment with a liquid crystal display screen, and the fingerprint detection area of the under-screen fingerprint identification device is at least partially positioned in the display area of the liquid crystal display screen; fingerprint identification device includes the fingerprint identification module under the screen, and the fingerprint identification module is located liquid crystal display's backlight unit below, and the fingerprint detection light that carries fingerprint information of the finger reflection of fingerprint detection area top sees through liquid crystal display and transmits to fingerprint sensor, receives and discerns fingerprint image through fingerprint sensor. Wherein, backlight unit is including range upon range of diffusion barrier and the light guide plate that sets up, the light guide plate is located the diffusion barrier below, through set up a plurality of interval distribution's micro-structure on the surface towards light guide plate one side at the diffusion barrier, a plurality of micro-structures support between diffusion barrier and light guide plate, the micro-structure can increase the interval between diffusion barrier and the light guide plate, and then the air gap between diffusion barrier and the light guide plate has been increased, and can make the air gap of each position more even, and then can avoid fingerprint detection light to produce the film interference phenomenon when seeing through between diffusion barrier and the light guide plate, can eliminate the interference light that produces by the film interference phenomenon to fingerprint imaging's interference, guarantee fingerprint imaging effect, so that fingerprint sensor obtains clear fingerprint image.

Example two

On the basis of the first embodiment, the present embodiment provides an underscreen fingerprint identification system, which includes a liquid crystal display 2 and the underscreen fingerprint identification apparatus 1 described in the first embodiment, where the liquid crystal display 2 includes a display module 21 and a backlight module 22, and the backlight module 22 is located below the display module 21.

Specifically, in this embodiment, reference may be made to the description of the first embodiment on the fingerprint identification device 1 and the backlight module 22, and in this embodiment, no further description is given to the fingerprint identification device 1 and the backlight module 22.

Liquid crystal display 2 generally includes display module 21 and the backlight unit 22 that is located display module 21 below, display module 21 can include transparent protection apron 211 and the liquid crystal display panel 212 that is located transparent protection apron 211 below, fingerprint identification module 11 is located backlight unit 22 below, be formed with the light transmission area that is used for making fingerprint detection light to see through on backlight unit 22, the light transmission area can be referred to backlight unit 22's relevant optics diaphragm and is formed the region that is non-light tight about the wave band of fingerprint detection light in the transmission route of fingerprint detection light, fingerprint identification module 11 is located below backlight unit 22's light transmission area, so that fingerprint detection light sees through backlight unit 22 and transmits fingerprint identification module 11.

Specifically, in this embodiment, the light-transmitting area may be an area corresponding to a transmission path of the fingerprint detection light on the liquid crystal display screen 2, and the transmission waveband of the detection light covers the reflection waveband of the detection light, so that the detection light and the fingerprint detection light formed by the detection light at the finger can penetrate through the light-transmitting area of the backlight module 22.

It should be noted that, in practical application, can adjust the relative position between detection light source 12, backlight unit 22's the light transmission area as required, and the fingerprint identification module 11, but detection light source 12 after the adjustment, backlight unit 22's the light transmission area, and the relative position between the fingerprint identification module 11, the finger that the detection light that needs to satisfy the emission of detection light source 12 can shine the fingerprint detection area top, and the fingerprint detection light that forms through finger reflection or transmission can get into fingerprint identification module 11 through backlight unit 22's light transmission area.

The system for identifying the fingerprint under the screen provided by the embodiment comprises a liquid crystal display screen and the fingerprint identification device under the screen, wherein a fingerprint detection area of the fingerprint identification device under the screen is at least partially positioned in a display area of the liquid crystal display screen; fingerprint identification device includes the fingerprint identification module under the screen, and the fingerprint identification module is located liquid crystal display's backlight unit below, and the fingerprint detection light that carries fingerprint information of the finger reflection of fingerprint detection area top sees through liquid crystal display and transmits to fingerprint sensor, receives and discerns fingerprint image through fingerprint sensor. Wherein, backlight unit is including range upon range of diffusion barrier and the light guide plate that sets up, the light guide plate is located the diffusion barrier below, through set up a plurality of interval distribution's micro-structure on the surface towards light guide plate one side at the diffusion barrier, a plurality of micro-structures support between diffusion barrier and light guide plate, the micro-structure can increase the interval between diffusion barrier and the light guide plate, and then the air gap between diffusion barrier and the light guide plate has been increased, and can make the air gap of each position more even, and then can avoid fingerprint detection light to produce the film interference phenomenon when seeing through between diffusion barrier and the light guide plate, can eliminate the interference light that produces by the film interference phenomenon to fingerprint imaging's interference, guarantee fingerprint imaging effect, so that fingerprint sensor obtains clear fingerprint image.

EXAMPLE III

On the basis of the first embodiment, the embodiment provides a liquid crystal display 2 supporting the fingerprint identification function under the screen, the fingerprint identification device 1 of the first embodiment is disposed under the liquid crystal display 2, the liquid crystal display 2 includes a display module 21 and a backlight module 22, the backlight module 22 is disposed under the display module 21 and is used for providing backlight for the display module 21 and transmitting the fingerprint detection light formed by the fingers above the liquid crystal display 2 to the fingerprint sensor 112 below the backlight module 22.

Fingerprint identification device 1 is including detecting light source 12 and fingerprint identification module 11 under the screen, wherein, detects light source 12 and is used for emitting the probe light to the finger that is located fingerprint detection area top, the probe light shines the finger of fingerprint detection area top, form the fingerprint detection light that carries fingerprint information after finger reflection or transmission, fingerprint identification module 11 is used for receiving the fingerprint detection light that carries fingerprint information that sees through liquid crystal display 2 to acquire the fingerprint image of finger.

In this embodiment, reference may be made to the description of the backlight module 22 in the first embodiment, and in this embodiment, no further description is made on the backlight module 22.

The below that the liquid crystal display that this embodiment provided is provided with fingerprint recognition device under the screen, and liquid crystal display includes display module assembly and the backlight unit who is located display module assembly below. Wherein, backlight unit is including range upon range of diffusion barrier and the light guide plate that sets up, the light guide plate is located the diffusion barrier below, through set up a plurality of interval distribution's micro-structure on the surface towards light guide plate one side at the diffusion barrier, a plurality of micro-structures support between diffusion barrier and light guide plate, the micro-structure can increase the interval between diffusion barrier and the light guide plate, and then the air gap between diffusion barrier and the light guide plate has been increased, and can make the air gap of each position more even, and then can avoid fingerprint detection light to produce the film interference phenomenon when seeing through between diffusion barrier and the light guide plate, can eliminate the interference light that produces by the film interference phenomenon to fingerprint imaging's interference, guarantee fingerprint imaging effect, so that fingerprint sensor obtains clear fingerprint image.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An under-screen fingerprint identification device is suitable for an electronic device with a liquid crystal display screen, and is characterized in that a fingerprint detection area of the under-screen fingerprint identification device is at least partially positioned in a display area of the liquid crystal display screen;

the under-screen fingerprint identification device comprises a fingerprint identification module positioned below a backlight module of the liquid crystal display screen, and the fingerprint identification module is used for receiving fingerprint detection light which is formed by reflection of a finger above the fingerprint detection area and penetrates through the liquid crystal display screen so as to obtain a fingerprint image of the finger;

the backlight module comprises a diffusion film and a light guide plate which is adjacently arranged below the diffusion film, wherein the surface of the diffusion film facing the light guide plate is provided with a plurality of microstructures which are distributed at intervals, the microstructures are used for increasing the distance between the diffusion film and the light guide plate, and the phenomenon of film interference generated when fingerprint detection light penetrates through the diffusion film and the light guide plate is avoided.

2. The underscreen fingerprint identification device of claim 1, wherein the microstructures are raised structures formed on a surface of the diffusion film.

3. The underscreen fingerprint identification device of claim 2, wherein the microstructures are hemispherical convex structures.

4. The underscreen fingerprint identification device of claim 3, wherein the radius of curvature of the microstructure is between 120 and 170 μm, and the height of the microstructure is between 1-3 μm.

5. The underscreen fingerprint identification device of any one of claims 2-4 wherein a plurality of the microstructures are uniformly spaced on the surface of the diffuser film.

6. The underscreen fingerprint identification device of claim 5, wherein the plurality of microstructures are uniformly spaced along the length and width directions of the diffuser film.

7. The device of claim 6, wherein a pitch between every two adjacent rows of the microstructures is equal to a pitch between every two adjacent columns of the microstructures.

8. The device for identifying the underscreen fingerprint is characterized in that a plurality of the microstructures are uniformly arranged at intervals along the length direction of the diffusion film, the distance between every two adjacent rows of the microstructures is equal, and the microstructures between every two adjacent rows are staggered mutually.

9. The underscreen fingerprint identification device of claim 8, wherein the microstructures are equidistant from two microstructures of an adjacent row that are staggered back and forth therefrom.

10. The underscreen fingerprint identification device of claim 9 wherein a pitch between two adjacent microstructures in two adjacent rows is equal to a pitch between two adjacent microstructures in the same row.

11. The device according to claim 6 or 8, wherein the distance between two adjacent columns of the microstructures is between 200 and 450 μm.

12. The underscreen fingerprint identification device of any one of claims 5-11, wherein the surface of the light guide plate facing the diffusion film is provided with a plurality of raised light guide strips, the light guide strips extend along the width direction of the light guide plate, and the plurality of light guide strips are uniformly spaced along the length direction of the light guide plate.

13. The underscreen fingerprint identification device of claim 12, wherein the light guide strip extends from one side to another side of the light guide plate in a width direction.

14. The underscreen fingerprint identification device of claim 13, wherein the cross-section of the light guide bar is circular arc-shaped.

15. The underscreen fingerprint identification device of claim 14 wherein the radius of curvature of the cross section of the light guide bar is between 30-150 μm and the height of the light guide bar is between 1-5 μm.

16. The underscreen fingerprint identification device of claim 15, wherein the distance between the centerlines of two adjacent light guide bars is between 40-150 μm.

17. The device of claim 12, wherein a surface of the light guide plate facing away from the diffuser film has a plurality of light guiding particles spaced apart from each other, the light guiding particles being supported between the light guide plate and the reflective film of the backlight module.

18. The underscreen fingerprint identification device of claim 17, wherein the height of the light guiding particles is between 3-5 μ ι η.

19. The underscreen fingerprint identification device of claim 17, wherein different regions of the surface of the light guide plate facing away from the diffuser film have different densities of the light guide particles.

20. The device as claimed in any one of claims 5 to 19, wherein the backlight module further comprises a brightness enhancement film disposed adjacent to and above the diffuser film, and a surface of the brightness enhancement film facing the diffuser film has a plurality of brightness enhancement particles spaced apart from each other.

21. The underscreen fingerprint identification device of claim 20, wherein the brightness enhancing particles are microsphere structures embedded in the brightness enhancing film and have a diameter between 4-10 μm.

22. The device of claim 21, wherein the brightness enhancing particles are uniformly distributed across the surface of the brightness enhancing film.

23. The device according to any one of claims 1 to 22, further comprising a detection light source for emitting a detection light, wherein the detection light is irradiated to a finger above the fingerprint identification area through the liquid crystal display screen, and forms the fingerprint detection light carrying fingerprint information by reflection of the finger.

24. The device according to claim 23, wherein the detection light has a different wavelength from a backlight provided by the backlight module for displaying a picture.

25. The device according to claim 24, wherein the detection light is infrared light, and the backlight provided by the backlight module is visible light.

26. The utility model provides a backlight unit, is applicable to the liquid crystal display who supports fingerprint identification function under the screen, and its characterized in that is in including diffusion barrier and adjacent setting the light guide plate of diffusion barrier below, the diffusion barrier face the surface of light guide plate has a plurality of interval distribution's micro-structure, the micro-structure is used for increasing the diffusion barrier with interval between the light guide plate avoids fingerprint detection light sees through the diffusion barrier with produce light interference when between the light guide plate.

27. A backlight module according to claim 26, wherein the microstructures are raised structures formed on the surface of the diffuser film.

28. A backlight module according to claim 27, wherein the microstructures are hemispherical convex structures.

29. The backlight module as claimed in claim 28, wherein the radius of curvature of the microstructures is between 120 μm and 170 μm, and the height of the microstructures is between 1 μm and 3 μm.

30. A backlight module according to any one of claims 27-29, wherein the microstructures are uniformly spaced on the surface of the diffuser film.

31. A backlight module according to claim 30, wherein the microstructures are uniformly spaced along the length and width of the diffuser film.

32. A backlight module according to claim 31, wherein the pitch between every two adjacent rows of the microstructures is equal to the pitch between every two adjacent columns of the microstructures.

33. The backlight module according to claim 30, wherein the microstructures are uniformly spaced along the length of the diffuser film, the distance between every two adjacent rows of the microstructures is equal, and the microstructures in two adjacent rows are staggered.

34. A backlight module according to claim 33, wherein the microstructures are equidistant from two microstructures of an adjacent row staggered from front to back.

35. A backlight module according to claim 34, wherein the pitch between two adjacent microstructures in two adjacent rows is equal to the pitch between two adjacent microstructures in the same row.

36. The backlight module as claimed in claim 31 or 33, wherein the pitch between two adjacent rows of the microstructures is between 200 μm and 450 μm.

37. A backlight module according to any one of claims 30-36, wherein the surface of the light guide plate facing the diffuser film has a plurality of raised light guide strips extending along the width of the light guide plate, and the plurality of light guide strips are uniformly spaced along the length of the light guide plate.

38. A backlight module according to claim 37, wherein the light guide strip extends from one side to the other side of the light guide plate in the width direction.

39. A backlight module according to claim 38, wherein the light guide strip has a circular arc cross-section.

40. A backlight module according to claim 39, wherein the radius of curvature of the cross-section of the light guide strip is between 30-150 μm and the height of the light guide strip is between 1-5 μm.

41. A backlight module according to claim 40, wherein the distance between the centerlines of two adjacent light guide bars is between 40-150 μm.

42. A backlight module according to claim 37, wherein a surface of the light guide plate facing away from the diffuser film has a plurality of light guiding particles spaced apart and supported between the light guide plate and the reflective film of the backlight module.

43. A backlight module according to claim 42, wherein the light directing particles have a height between 3-5 μm.

44. A backlight module according to claim 42, wherein different regions of the surface of the light guide plate facing away from the diffuser film have different densities of the light guide particles.

45. A backlight module according to any one of claims 30-44, further comprising a brightness enhancing film disposed adjacent the diffuser film, wherein a surface of the brightness enhancing film facing the diffuser film comprises a plurality of brightness enhancing particles in a spaced apart arrangement.

46. A backlight module according to claim 45, wherein the brightness enhancing particles are microsphere structures embedded in the brightness enhancing film and have a diameter of between 4-10 μm.

47. A backlight module according to claim 46, wherein the brightness enhancing particles are uniformly distributed across the surface of the brightness enhancing film.

48. An off-screen fingerprint identification system, comprising a liquid crystal display screen and the off-screen fingerprint identification device of any one of claims 1 to 25, wherein the liquid crystal display screen comprises a display module and the backlight module of any one of claims 26 to 47, and wherein the backlight module is located below the display module.

49. A liquid crystal display screen supporting an off-screen fingerprint identification function, wherein the off-screen fingerprint identification device according to any one of claims 1 to 25 is arranged below the liquid crystal display screen, and the liquid crystal display screen comprises a display module and the backlight module according to any one of claims 26 to 47, wherein the backlight module is arranged below the display module and is used for providing backlight for the display module and transmitting fingerprint detection light formed by fingers above the liquid crystal display screen to a fingerprint sensor below the backlight module.