CN111095287A

CN111095287A - Optical fingerprint device and electronic equipment

Info

Publication number: CN111095287A
Application number: CN201980004322.4A
Authority: CN
Inventors: 纪登鑫; 沈健; 姚国峰
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2019-08-08
Filing date: 2019-08-30
Publication date: 2020-05-01
Anticipated expiration: 2039-08-30
Also published as: CN111095287B

Abstract

An optical fingerprint device and an electronic device, the optical fingerprint device is arranged below a display screen of the electronic device, and comprises: the incident angle conversion structure is arranged below the display screen and used for converting a first optical signal returned from a finger above the display screen into a second optical signal, wherein the first optical signal is an optical signal inclined relative to the display screen, and the second optical signal is an optical signal vertical relative to the display screen; the optical assembly is arranged below the incidence angle conversion structure and used for receiving the second optical signal and transmitting the second optical signal to the optical sensor; the optical sensor comprises a plurality of optical sensing units, is arranged below the optical assembly and is used for receiving optical signals transmitted by the optical assembly, and the optical signals are used for acquiring fingerprint information of the finger.

Description

Optical fingerprint device and electronic equipment

This application claims priority from PCT patent applications with the application number PCT/CN2019/099822, entitled "fingerprint detection device and electronic device", filed by the chinese patent office on 8/2019, the entire contents of which are incorporated herein by reference.

Technical Field

The embodiments of the present application relate to the field of optical fingerprint technology, and more particularly, to an optical fingerprint device and an electronic apparatus.

Background

With the rapid development of the terminal industry, people pay more and more attention to the biometric identification technology, and the practicability of the more convenient under-screen biometric identification technology, such as the under-screen optical fingerprint identification technology, has become a requirement of the public.

Optical fingerprint identification technique under the screen sets up the optical fingerprint module in the display screen under, through gathering optical fingerprint image, realizes fingerprint identification. With the development of terminal products, the requirements on fingerprint identification performance are higher and higher. Therefore, how to improve the performance of fingerprint identification becomes a technical problem to be solved urgently.

Disclosure of Invention

The embodiment of the application provides an optical fingerprint device and electronic equipment, and fingerprint identification performance can be improved.

In a first aspect, an optical fingerprint device is provided, configured to be disposed below a display screen of an electronic device, including: the incident angle conversion structure is arranged below the display screen and used for converting a first optical signal returned from a finger above the display screen into a second optical signal, wherein the first optical signal is an optical signal inclined relative to the display screen, and the second optical signal is an optical signal vertical relative to the display screen; the optical assembly is arranged below the incidence angle conversion structure and used for receiving the second optical signal and transmitting the second optical signal to the optical sensor; the optical sensor comprises a plurality of optical sensing units, is arranged below the optical assembly and is used for receiving optical signals transmitted by the optical assembly, and the optical signals are used for acquiring fingerprint information of the finger.

In some possible implementations, the incident angle conversion structure includes a micro prism array including a plurality of micro prism units, each micro prism unit includes at least one micro prism, each micro prism includes at least one first incident surface and at least one first exit surface, the first incident surface is inclined with respect to a plane of the display screen, and the first exit surface is parallel to the plane of the display screen.

In some possible implementations, each of the micro-prism units includes a micro-prism, and an optical sensing unit or a row of optical sensing units is disposed below the micro-prism; or

Each micro prism unit comprises a plurality of micro prisms which are distributed in a central symmetry mode, wherein a plurality of optical sensing units are arranged below the micro prisms.

In some possible implementations, the incidence planes of the plurality of microprisms are oriented in different directions with respect to the plane of the optical sensor.

In some possible implementations, the plurality of microprisms includes four microprisms, and incident surfaces of adjacent ones of the four microprisms are angularly separated by 90 degrees with respect to the direction of the optical sensor.

In some possible implementations, the first optical signal forms a first angle with a direction perpendicular to the optical sensor

The first incident surface and the first incident surface of each micro prismThe emergent surface forms a second included angle theta, wherein the first included angle theta

The second angle θ, the refractive index n of the propagation medium of the first optical signal₁Refractive index n of the microprisms₂The following relationship is satisfied:

in some possible implementations, each of the micro prisms includes at least one first supporting surface provided with a reflective layer.

In some possible implementation manners, the first optical signal is incident to the first incident surface and enters the micro prism to form a third optical signal, the third optical signal is incident to the first incident surface again after being reflected by the first supporting surface, and the second optical signal is emitted vertically after being reflected again by the first incident surface, wherein a first included angle is formed between the first optical signal and a direction perpendicular to the optical sensor

The first incident surface and the first emergent surface of each micro prism form a second included angle theta, the third optical signal and the direction perpendicular to the first incident surface form a third included angle α, the third optical signal and the direction parallel to the first emergent surface form a fourth included angle β, wherein the first included angle

The second angle θ, the third angle α, the fourth angle β, a refractive index n of a propagation medium of the first optical signal₁Refractive index n of the microprisms₂The following relationship is satisfied:

β＝(90°-θ)+α

θ＝(90°-θ)。

in some possible implementations, the optical fingerprint device further includes:

and the light-transmitting coating is arranged on the incident surface of the incident light conversion structure and comprises at least one second incident surface and at least one second emergent surface, wherein the first optical signal enters the light-transmitting coating from the second incident surface to form a fourth optical signal, and the fourth optical signal is emergent from the second emergent surface, is incident to the incident light conversion structure and is converted into the second optical signal which is emergent vertically by the incident light conversion structure.

The light-transmitting coating with the high refractive index is arranged on the incident surface of the incident angle conversion structure, so that a first light signal returned from a finger can be converted into a light signal which is vertically emitted after being refracted twice, on one hand, the direction of the incident light can be converted, so that the incident light conversion structure is just right opposite to the light signal of the incident surface of the incident light conversion structure, the light signal is refracted on the air/light-transmitting coating interface and then converted into a vertical light signal, and finally reaches the optical sensor.

In some possible implementation manners, the second emergent surface is parallel to the incident surface of the incident light conversion structure, the second incident surface is parallel to the emergent surface of the incident light conversion structure, and the first optical signal forms a first included angle with a direction perpendicular to the second incident surface

The incident surface of the incident light conversion structure and the emergent surface of the incident light conversion structure form a second included angle theta, the fourth optical signal and the direction perpendicular to the incident surface of the incident light conversion structure form a third included angle α, wherein the first included angle

The second included angle theta, the third included angle α, and the refractive index n of the light-transmitting coating layer₀Refractive index n of the propagation medium of said first optical signal₁And refractive index n of the microprisms₂The following relationship is satisfied:

n₁sinα＝n₂sinθ。

in some possible implementations, the light-transmitting coating is prepared on the incident surface of the incident light conversion structure by spin coating or spray coating.

In some possible implementations, the at least one second incident surface of the light-transmissive coating is provided with an anti-reflection coating for reducing the reflectivity of the first optical signal at the at least one second incident surface and/or a polarization coating for selecting the polarization direction of the first optical signal.

In some possible implementations, the optical assembly includes at least one light blocking layer disposed below the microlens array and a microlens array, each of the at least one light blocking layer having an opening disposed therein;

wherein the micro-lens array is used for transmitting the received second optical signal to the optical sensor through the opening in the at least one light blocking layer.

In some possible implementations, the at least one light blocking layer includes a first light blocking layer disposed at a back focal plane position of the microlens array.

In some possible implementations, the first light blocking layer is a metal layer of the optical sensor.

In some possible implementations, the optical assembly further includes:

an optical filter provided in at least one of the following positions:

the incident angle conversion structure and the micro lens array;

between the microlens array and the optical sensor.

In some possible implementations, the optical assembly includes a straight hole collimator including a plurality of collimating holes, and each optical sensing unit in the optical sensor corresponds to at least one collimating hole in the straight hole collimator, wherein the straight hole collimator is configured to receive the second optical signal converted by the incident light conversion structure and transmit the second optical signal to the plurality of optical sensing units through the collimating holes in the straight hole collimator.

In some possible implementations, the straight hole alignment unit is formed by a metal layer and a metal via layer of the optical sensing unit.

In some possible implementations, the optical assembly further includes:

an optical filter provided in at least one of the following positions:

the incident angle conversion structure and the straight hole collimator;

the straight hole collimator and the optical sensing unit.

In some possible implementations, the display screen is an organic light emitting diode OLED display screen, and the optical fingerprint device utilizes a portion of the display units of the OLED display screen as an excitation light source for optical fingerprint detection.

In a second aspect, an electronic device is provided, comprising:

a display screen;

and the optical fingerprint device of the first aspect or any possible implementation manner of the first aspect, wherein the optical fingerprint device is disposed below the display screen.

In some possible implementations, the display screen is an organic light emitting diode OLED display screen, and the display screen includes a plurality of OLED light sources, wherein the optical fingerprint device uses at least a portion of the OLED light sources as an excitation light source for optical fingerprint detection.

According to the technical scheme, the incident angle conversion structure is arranged above the optical assembly, so that inclined incident light can be converted into vertical incident light to be incident on the optical assembly, light loss caused by the inclined light can be reduced, the signal quantity of optical signals received by the optical sensor can be increased, exposure time can be shortened, and fingerprint identification speed is increased.

Drawings

Fig. 1 is a schematic plan view of an electronic device to which the present application may be applied.

Fig. 2 is a schematic partial cross-sectional view of the electronic device shown in fig. 1 along a '-a'.

Fig. 3 is a schematic diagram of a fingerprint detection device for performing fingerprint detection based on oblique light.

Fig. 4 is a schematic view of another fingerprint detection device based on oblique light for fingerprint detection.

Fig. 5 is a schematic block diagram of an optical fingerprint device according to an embodiment of the present application.

Fig. 6 is a schematic cross-sectional view of an example of an optical fingerprint device according to an embodiment of the present application.

Fig. 7 is a schematic view of the working principle of the microprism.

Fig. 8 is a schematic illustration of the working principle of a microprism whose support surface is provided with a reflective coating.

Fig. 9 is a perspective view of a microprism array of fig. 6.

Fig. 10 is a schematic configuration diagram of a top view of the optical fingerprint device shown in fig. 6.

Fig. 11 is another exemplary schematic cross-sectional view of an optical fingerprint device according to an embodiment of the present application.

Fig. 12 and 13 are top views of the microprism unit of fig. 11.

Fig. 14 is a schematic cross-sectional view of another example of an optical fingerprint device according to an embodiment of the present application.

Fig. 15 is a schematic block diagram of a field of view of an optical fingerprint device according to an embodiment of the present application.

Fig. 16 is a schematic cross-sectional view of an example of an optical fingerprint device including a microprism array and a light transmissive coating.

Fig. 17 is a schematic diagram of the operating principle of the structure shown in fig. 16.

Fig. 18 is another exemplary schematic cross-sectional view of an optical fingerprint device including a microprism array and a light transmissive coating.

Fig. 19 is a schematic cross-sectional view of yet another example of an optical fingerprint device including a microprism array and a light transmissive coating.

Fig. 20 is a schematic structural diagram of an electronic apparatus according to an embodiment of the present application.

Detailed Description

The technical solution in the embodiments of the present invention will be described below with reference to the accompanying drawings.

As a common application scenario, the fingerprint identification device provided by the embodiment of the application can be applied to smart phones, tablet computers and other mobile terminals or other terminal devices with display screens; more specifically, in the terminal device described above, the fingerprint recognition device may be embodied as an optical fingerprint device, which may be disposed in a partial area or an entire area below the display screen, thereby forming an Under-screen (Under-display) optical fingerprint system.

Fig. 1 and fig. 2 are schematic diagrams illustrating an electronic device to which an embodiment of the present application may be applied, where fig. 1 is an orientation schematic diagram of an electronic device 10, and fig. 2 is a schematic diagram of a partial cross-sectional structure of the electronic device 10 shown in fig. 1 along a '-a'.

As shown in fig. 1 to 2, the electronic device 10 includes a display screen 120 and an optical fingerprint device 130, wherein the optical fingerprint device 130 is disposed in a partial area below the display screen 120, for example, below a middle area of the display screen. The optical fingerprint device 130 comprises an optical fingerprint sensor, the optical fingerprint sensor comprises a sensing array with a plurality of optical sensing units, and the area where the sensing array is located or the sensing area is the fingerprint detection area 103 of the optical fingerprint device 130. As shown in fig. 1, the fingerprint detection area 103 is located in a display area of the display screen 120.

It should be appreciated that the area of the fingerprint sensing area 103 may be different from the area of the sensing array of the optical fingerprint device 130, for example, by using a light path design such as lens imaging, a reflective folded light path design, or other light converging or reflecting light path design, the area of the fingerprint sensing area 103 of the optical fingerprint device 130 may be larger than the area of the sensing array of the optical fingerprint device 130. In other alternative implementations, the fingerprint sensing area 103 of the optical fingerprint device 130 may be designed to substantially coincide with the area of the sensing array of the optical fingerprint device 130 if optical path guidance is performed, for example, by light collimation.

Therefore, when the user needs to unlock the terminal device or perform other fingerprint verification, the user only needs to press a finger on the fingerprint detection area 103 of the display screen 120, so as to realize fingerprint input. Since fingerprint detection can be implemented in the screen, the electronic device 10 with the above structure does not need to reserve a special space on the front surface thereof to set a fingerprint key (such as a Home key), so that a full-screen scheme can be adopted, that is, the display area of the display screen 120 can be substantially extended to the front surface of the whole electronic device 10.

As an alternative implementation, as shown in fig. 2, the optical fingerprint device 130 includes a light detection portion 134 and an optical component 132, where the light detection portion 134 includes the sensing array and a reading circuit and other auxiliary circuits electrically connected to the sensing array, which can be fabricated on a chip (Die) through a semiconductor process, such as an optical imaging chip or an optical fingerprint sensor, the 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 can be used as the optical sensing units as described above; the optical assembly 132 may be disposed above the sensing array of the light detecting portion 134, and may specifically include a Filter layer (Filter) for filtering out ambient light penetrating the finger, such as infrared light interfering with imaging, and a light guiding layer or light path guiding structure for guiding reflected light reflected from the surface of the finger to the sensing array for optical detection, and other optical elements.

In particular implementations, the optical assembly 132 may be packaged with the same optical fingerprint component as the light detection portion 134. For example, the optical component 132 may be packaged in the same optical fingerprint chip as the optical detection portion 134, or the optical component 132 may be disposed outside the chip where the optical detection portion 134 is located, for example, the optical component 132 is attached to the chip, or some components of the optical component 132 are integrated into the chip.

For example, the light guide layer may specifically be a Collimator (collimater) layer manufactured on a semiconductor silicon wafer, and the collimater unit may specifically be a small hole, and in reflected light reflected from a finger, light perpendicularly incident to the collimater unit may pass through and be received by an optical sensing unit below the collimater unit, and light with an excessively large incident angle is attenuated by multiple reflections inside the collimater unit, so that each optical sensing unit can basically only receive reflected light reflected from a fingerprint pattern directly above the optical sensing unit, and the sensing array can detect a fingerprint image of the finger.

In another embodiment, the light guiding layer or the light path guiding structure may also be an optical Lens (Lens) layer, which has one or more Lens units, such as a Lens group composed of one or more aspheric lenses, and is used to converge the reflected light reflected from the finger to the sensing array of the light detecting portion 134 therebelow, so that the sensing array can perform imaging based on the reflected light, thereby obtaining the fingerprint image of the finger. Optionally, the optical lens layer may further form a pinhole in the optical path of the lens unit, and the pinhole may cooperate with the optical lens layer to enlarge the field of view of the optical fingerprint device, so as to improve the fingerprint imaging effect of the optical fingerprint device 130.

In other embodiments, the light guide layer or the light path guiding structure may also specifically adopt a Micro-Lens (Micro-Lens) layer, the Micro-Lens layer has a Micro-Lens array formed by a plurality of Micro-lenses, which may be formed above the sensing array of the light detecting portion 134 through a semiconductor growth process or other processes, and each Micro-Lens may respectively correspond to one of the sensing units of the sensing array. And another optical film layer, such as a dielectric layer or a passivation layer, may be further formed between the microlens layer and the sensing unit, and more specifically, a light blocking layer having micro holes may be further included between the microlens layer and the sensing unit, where the micro holes are formed between the corresponding microlenses and the sensing unit, and the light blocking layer may block optical interference between the adjacent microlenses and the sensing unit, and enable light corresponding to the sensing unit to be converged inside the micro holes through the microlenses and transmitted to the sensing unit through the micro holes for optical fingerprint imaging.

It should be understood that several implementations of the above-mentioned optical path guiding structure may be used alone or in combination, for example, a microlens layer may be further disposed below the collimator layer or the optical lens layer. Of course, when the collimator layer or the optical lens layer is used in combination with the microlens layer, the specific lamination structure or optical path thereof may need to be adjusted according to actual needs.

As an alternative embodiment, the display screen 120 may adopt a display screen having a self-Light Emitting display unit, such as an Organic Light-Emitting Diode (OLED) display screen or a Micro-LED (Micro-LED) display screen. Taking an OLED display screen as an example, the optical fingerprint device 130 may use the display unit (i.e., OLED light source) of the OLED display screen 120 located in the fingerprint detection area 103 as an excitation light source for optical fingerprint detection. When a finger is pressed against the fingerprint detection area 103, the display 120 emits a beam of light to a target finger above the fingerprint detection area 103, the light being reflected at the surface of the finger to form reflected light or scattered light by scattering inside the finger, which is collectively referred to as reflected light for convenience of description in the related patent application. Because ridges (ridges) and valleys (valley) of the fingerprint have different light reflection capacities, reflected light from the ridges and emitted light from the valleys have different light intensities, and the reflected light is received by the sensing array in the optical fingerprint device 130 and converted into corresponding electric signals, i.e., fingerprint detection signals, after passing through the optical assembly; fingerprint image data can be obtained based on the fingerprint detection signal, and fingerprint matching verification can be further performed, so that an optical fingerprint identification function is realized in the electronic device 10. In other embodiments, the optical fingerprint device 130 may also use an internal light source or an external light source to provide an optical signal for fingerprint detection.

In other embodiments, the optical fingerprint device 130 may also use an internal light source or an external light source to provide an optical signal for fingerprint detection. In this case, the optical fingerprint device 130 may be adapted for use with a non-self-emissive display such as a liquid crystal display or other passively emissive display. Taking an application to a liquid crystal display having a backlight module and a liquid crystal panel as an example, to support the underscreen fingerprint detection of the liquid crystal display, the optical fingerprint system of the terminal device 10 may further include an excitation light source for optical fingerprint detection, where the excitation light source may specifically be an infrared light source or a light source of non-visible light with a specific wavelength, and may be disposed below the backlight module of the liquid crystal display or in an edge area below a protective cover of the terminal device 10, and the optical fingerprint device 130 may be disposed below the edge area of the liquid crystal panel or the protective cover and guided through a light path so that the fingerprint detection light may reach the optical fingerprint device 130; alternatively, the optical fingerprint device 130 may be disposed below the backlight module, and the backlight module may be perforated or otherwise optically designed to allow the fingerprint detection light to pass through the liquid crystal panel and the backlight module and reach the optical fingerprint device 130. In other alternative implementations, the display screen 120 may also be a non-self-luminous display screen, such as a liquid crystal display screen that uses a backlight; in this case, the optical detection device 130 cannot use the display unit of the display screen 120 as an excitation light source, so that it is necessary to integrate the excitation light source inside the optical detection device 130 or arrange the excitation light source outside the optical detection device 130 to realize optical fingerprint detection, and when the optical fingerprint device 130 uses an internal light source or an external light source to provide an optical signal for fingerprint detection, the detection principle is the same as that described above.

It should be appreciated that in particular implementations, the electronic device 10 also includes a transparent protective cover positioned over the display screen 120 and covering the front of the electronic device 10. Because, in the present embodiment, the pressing of the finger on the display screen 120 actually means pressing on the cover plate above the display screen 120 or the surface of the protective layer covering the cover plate.

On the other hand, in some embodiments, the optical fingerprint device 130 may include only one optical fingerprint sensor, where the area of the fingerprint detection area 103 of the optical fingerprint device 130 is small and the location is fixed, so that the user needs to press a finger to a specific location of the fingerprint detection area 103 when performing a fingerprint input, otherwise the optical fingerprint device 130 may not acquire a fingerprint image and the user experience is poor. In other alternative embodiments, the optical fingerprint device 130 may specifically include a plurality of optical fingerprint sensors; the plurality of optical fingerprint sensors may be disposed in the middle area of the display screen 120 side by side in a splicing manner, and sensing areas of the plurality of optical fingerprint sensors jointly form the fingerprint detection area 103 of the optical fingerprint device 130. That is, the fingerprint detection area 103 of the optical fingerprint device 130 may include a plurality of sub-areas, each of which corresponds to a sensing area of one of the optical fingerprint sensors, so that the fingerprint capture area 103 of the optical fingerprint device 130 may be extended to a main area of the middle portion of the display screen, i.e., to a usual finger pressing area, thereby implementing a blind-touch fingerprint input operation. Alternatively, when the number of optical fingerprint sensors is sufficient, the fingerprint detection area 130 may also be extended to half or even the entire display area, thereby enabling half-screen or full-screen fingerprint detection.

Optionally, in some embodiments of the present application, the optical fingerprint device 130 may further include a Circuit board for transmitting signals (e.g., the fingerprint detection signals), for example, the Circuit board may be a Flexible Printed Circuit (FPC). The optical fingerprint sensor may be connected to the FPC and enable electrical interconnection and signal transmission through the FPC with other peripheral circuits or other components in the electronic device. For example, the optical fingerprint sensor may receive a control signal of a processing unit of the electronic device through the FPC, and may also output a fingerprint detection signal (e.g., a fingerprint image) to the processing unit or the control unit of the electronic device through the FPC, or the like.

It is to be noted that, in the embodiments shown below, the same reference numerals are given to the same structures among the structures shown in the different embodiments for the convenience of understanding, and a detailed description of the same structures is omitted for the sake of brevity.

It should be understood that the heights or thicknesses of the various structural members in the embodiments of the present application shown below, as well as the overall thickness of the optical fingerprint device, are illustrative only and should not be construed as limiting the present application in any way.

In some embodiments, in order to improve the flexibility of fingerprint identification, a scheme for fingerprint detection based on oblique light is proposed, and fig. 3 and 4 respectively show schematic structural diagrams of a fingerprint detection device for fingerprint detection based on oblique light.

As shown in fig. 3, the fingerprint detection device 20 may include a micro-lens 21, a micro-aperture stop 22 disposed on a back focal plane 211 of the micro-lens 21, an optical sensing unit 23 disposed below the micro-aperture stop 22, and an optical filter 25 disposed above the micro-lens 21.

When the incident angle is

After entering the fingerprint detection device 20, the finger reflection light 24 firstly passes through the optical filter 25, the optical filter 25 has high transmittance to light in a visible light band and low transmittance to infrared light, and can be used for preventing light signals in an infrared band in sunlight from penetrating through the finger and the fingerprintThe acquisition of the image causes interference. The reflected light 24 then passes through the microlens 21 and is focused to a point F on the back focal plane 211 of the microlens₁. Wherein, F₁From the back focus F of the microlens 21₀Distance F of₀F₁Can be expressed approximately as:

where r is the radius of curvature of the microlens 21 and n is the refractive index of the microlens 21. The aperture diaphragm 22 is disposed at F1, the non-light-transmitting layer 220 is disposed in the region other than the aperture diaphragm 22, and the size of the aperture diaphragm determines the angle range of the incident light that can pass through

Only the incident angle is

To

The finger-reflected light 24 within the range can reach the optical sensing unit 23. The combination of the micro-lens 21 and the aperture stop 22 can realize the angle screening of the incident light, and the incident light of the non-target angle is blocked by the non-transparent layer 220.

However, when it comes to receiving high angle optical signals (e.g. angle of incidence)

Greater than 30 degrees), the solution shown in fig. 3 faces two problems: firstly, the transmittance of the filter 25 for the incident light with large angle is lower than that of the incident light with normal angle; secondly, a part of the area of the microlens 21 (e.g. the area 241 in fig. 3) cannot converge due to the shadow effect (lens shading effect). Therefore, when the fingerprint detection device 20 receives incident light with a larger angle, the light loss is larger, and therefore, the light loss must be largerBy extending the exposure time of the fingerprint detection device 20 to obtain a sufficient amount of signal, the fingerprint recognition time is longer, which affects the user experience.

As shown in fig. 4, the fingerprint detection device 30 may include an optical filter 35, an inclined hole collimator 36 (provided with a plurality of inclined holes 361) disposed below the optical filter 35, and an optical sensing unit 33 below the inclined hole collimator 36. Because the inclined hole 361 is arranged at an angle with the normal 310

Therefore, the optical sensor unit 33 can only receive the finger reflection light 34 with an incident angle of

Or is close to

The oblique optical signal of (1).

The solution shown in fig. 4 still has a problem that the filter 35 has a low transmittance for a large-angle oblique incident light. In addition, the process for manufacturing the inclined hole collimator 36 is relatively complex, the manufacturing difficulty is high, and the method is not suitable for large-scale production.

Further, in order to solve the above problem, an embodiment of the present application proposes an optical fingerprint device, as shown in fig. 5, the optical fingerprint device 70 may include an incident angle conversion structure 71, an optical assembly 72 and an optical sensor 73, wherein:

the incident angle converting structure 71 is disposed above the optical assembly 72, and is configured to convert a first optical signal returned from the finger into a second optical signal, wherein the first optical signal is an optical signal inclined with respect to a plane of the optical sensor, and the second optical signal is an optical signal perpendicular to the plane of the optical sensor;

the optical assembly 72 is disposed above the optical sensor 73, and is configured to receive the second optical signal and transmit the second optical signal to the optical sensor 73;

the optical sensor 73 may include a plurality of optical sensing units for receiving the second optical signal transmitted through the optical assembly 72 and acquiring fingerprint information of the finger according to the second optical signal.

Therefore, in the embodiment of the application, the incident angle conversion structure is arranged above the optical assembly, so that oblique incident light can be converted into vertical incident light to be incident on the optical assembly, light loss caused by oblique light incidence can be reduced, the signal quantity of an optical signal received by the optical sensor can be increased, and compared with the scheme of the inclined hole collimator, the technical scheme is simple in process and easy to implement.

Alternatively, in some embodiments, the incident angle converting structure 71 may be a structure composed of micro prisms, the micro prisms may have inclined incident surfaces, and may be used to convert incident light incident on the inclined incident surfaces into optical signals perpendicular to the display screen, or in other embodiments, the incident angle converting structure may also be a structure made of other materials with high refractive index, as long as the above-mentioned functions can be performed, and the present application is not limited thereto. Hereinafter, the incident angle conversion structure will be described as an example of a microprism structure, but the present invention is not limited thereto.

As one example, the optical fingerprint device 70 may be the optical fingerprint device 40 shown in FIG. 6. As shown in fig. 6, the optical fingerprint device 40 may include a light guiding portion 41 and a light detecting portion 42. Wherein the light guiding portion 41 may be used to guide the light signal reflected or scattered via the finger to the light detecting portion 42. The light-directing portion 41 may include an incident light converting structure and an optical component (e.g., optical component 132 of fig. 2) corresponding to the incident light converting structure 71 and the optical component 72 of fig. 5, respectively, and in further embodiments, the light-directing portion 41 may also include a light-transmissive coating, as described in detail below.

The light detecting part 42 corresponds to the optical sensor 73 in fig. 5, and may include an optical sensing array 424, which may include a plurality of optical sensing units. For example, the optical sensing array 424 may include a first optical sensing unit 424a, a second optical sensing unit 424b, and a third optical sensing unit 424 c. The optical sensing array 424 receives the optical signal for detecting the fingerprint information of the finger.

The incident light conversion structure may be, for example, the micro-prism array 410 shown in fig. 6, which may include a plurality of micro-prisms (micro-prisms), such as a first micro-prism 410a, a second micro-prism 410b, a third micro-prism 410c, and the like. The micro-prism array 410 may be used to convert a first optical signal reflected via a finger into a second optical signal. The first optical signal may be an optical signal inclined with respect to the display screen, and the second optical signal may be an optical signal perpendicular to the display screen. Alternatively, the first optical signal may be an optical signal inclined with respect to the plane of the light detecting section 42, and the second optical signal may be an optical signal perpendicular to the plane of the light detecting section 42.

In some embodiments, at least one optical sensing unit is disposed under each of the microprisms in the microprism array 410, for example, at least a first optical sensing unit 424a is disposed under the first microprism 410a, at least a second optical sensing unit 424b is disposed under the second microprism 410b, and at least a third optical sensing unit 424c is disposed under the third microprism 410 c.

Further, the light detecting portion 42 may further include at least one metal layer 421 and a dielectric layer 423. The metal layer 421 can be a metal wiring layer of the optical sensor array 424, and is used for electrically interconnecting the optical sensor units in the optical sensor array 424 and electrically connecting the optical sensor array 424 to an external device, so as to implement communication with other devices in an electronic apparatus. The dielectric layer may be disposed between the metal layers 421 and the optical sensing array 424, and the material of the dielectric layer 423 may be a transparent material.

In some embodiments of the present application, the optical assembly may be disposed between the microprism array 410 and the optical sensing array 424, and the optical assembly is used to screen or separate the second optical signal converted by the microprism array 410. That is, the optical assembly may be used to screen out a portion of the second optical signal converted by the microprism array 410 and direct the portion of the second optical signal to a specific optical sensing unit in the optical sensing array 424. In this embodiment, the optical assembly is configured to guide the second optical signal converted by the corresponding micro-prism to the optical sensing unit below the micro-prism. For example, after a first optical signal returned from a finger above the display screen is converted into a second optical signal by the micro-prism 410a, the second optical signal transmits the second optical signal converted by the micro-prism 410a to the optical sensing unit 424a disposed below the micro-prism 410a through the corresponding optical component (e.g., the micro-lens 412 a).

In an actual product, since the thickness of the micro prism array 410 is generally thin, it is possible to ensure that the thickness of the optical fingerprint device 40 is small.

It should be understood that fig. 6 only shows a scene where one micro-prism corresponds to one optical sensing unit, and in other embodiments, one micro-prism may correspond to a plurality of optical sensing units, that is, a plurality of optical sensing units may be disposed below the micro-prisms, that is, after a first optical signal returned from a finger above the display screen is converted into a second optical signal by the micro-prism, the second optical signal may be further transmitted to the plurality of optical sensing units through corresponding optical components, for example, if the micro-prism 410a corresponds to the

optical sensing units

424a and 424b, after the first optical signal returned from the finger above the display screen is converted into the second optical signal by the micro prism 410a, the second optical signal converted by the micro-prism 410a is further transmitted to the

optical sensing units

424a and 424b disposed below the micro-prism 410a through the corresponding optical component (e.g., the micro-lens 412 a).

Optionally, in some embodiments, when one micro prism corresponds to a plurality of optical sensing units, a projection of the micro prism on a plane where the optical sensing array is located covers the plurality of optical sensing units corresponding to the micro prism, so as to ensure that the optical signal converted by the micro prism can maximally reach the plurality of optical sensing units.

Alternatively, in some embodiments, the optical assembly may include a microlens array and at least one light blocking layer, as shown in fig. 6, the microlens array 413 includes a plurality of microlenses, for example, a first microlens 412a, a second microlens 412b, a third microlens 412c, and the like, disposed below the micro prism array 410; the at least one light blocking layer may be disposed between the microlens array 410 and the optical sensing array 424, and each of the at least one light blocking layer has an opening disposed therein corresponding to the microlens array or the optical sensing unit. Wherein the optical sensing array 424 is used for receiving the optical signal converged by the microlens array 412 and transmitted through the opening of the at least one light blocking layer. Alternatively, the microlens array 412 is configured to receive the second optical signal converted by the microprism array and transmit the second optical signal to the optical sensing array 424 through an opening in the at least one light blocking layer.

Alternatively, as an example, as shown in fig. 6, the at least one light-blocking layer includes a first light-blocking layer and a second light-blocking layer 414, wherein an opening corresponding to each microlens in the microlens array 412 is respectively disposed in the first light-blocking layer and the second light-blocking layer 414. For example, the metal layer 421 in the light detecting portion 42 can be reused as the first light blocking layer to simplify the structure of the optical fingerprint device, so that the first light blocking layer 421 is provided with a first opening 422a corresponding to the first microlens 412a, a second opening 422b corresponding to the second microlens 412b, and a third opening 422c corresponding to the third microlens 412 c. Similarly, a fourth opening 415a corresponding to the first microlens 412a, a fifth opening 415b corresponding to the second microlens 412b, and a sixth opening 415c corresponding to the third microlens 412c are disposed in the second light-blocking layer 414.

The first optical sensing unit 424a is configured to receive the optical signal converged by the first microlens 412a and transmitted through the fourth aperture 415a and the first aperture 422 a. The second optical sensing unit 424b is configured to receive the optical signal converged by the second microlens 412b and transmitted through the fifth opening 415b and the second opening 422 b. The third optical sensing unit 424c is configured to receive the optical signal converged by the third microlens 412c and transmitted through the sixth aperture 415c and the third aperture 422 c.

It should be understood that in the scheme shown in fig. 6, one microlens may correspond to one optical sensing unit, that is, the microlens may guide the second optical signal transmitted through the microprism to one optical sensing unit, or one microlens may correspond to a plurality of optical sensing units, that is, the microlens may guide the second optical signal transmitted through the microprism to a plurality of optical sensing units, in this case, one opening in the at least one light-blocking layer may also correspond to a plurality of optical sensing units, and the optical signals transmitted to the plurality of optical sensing units may all be transmitted through the one opening.

Therefore, compared with the scheme shown in fig. 4, in the scheme shown in fig. 6, the microprism array 410 converts the light signal reflected by the finger and inclined with respect to the display screen into a signal vertical to the display screen, and then the vertical light signal is converged by the microlens and the light blocking layer, so that the shadow effect of the edge area of the microlens can be reduced, the amount of the signal received by the optical sensing array 424 is increased, and the exposure time and the fingerprint identification time can be shortened.

Optionally, in some embodiments, the first light blocking layer is disposed at a back focal plane position of a microlens in the microlens array, wherein the back focal plane of the microlens array may be a plane formed by a back focal point of each microlens in the microlens array. The focusing point of the micro lens is in the opening in the first light blocking layer, so that the second optical signal obtained by the conversion of the micro prism enters the micro lens corresponding to the micro prism, is converged and transmitted to the opening in the first light blocking layer through the micro lens, and is further transmitted to the corresponding optical sensing unit through the opening.

As described above, the metal layer 421 in the light detecting section 42 can be reused as the first light blocking layer, that is, the first light blocking layer can be disposed inside the light detecting section 42, for example, the first light blocking layer 421 is formed by using a metal layer in a back-end-of-chip (BEOL) process, and the metal layer can be the metal layer 421 at any position in the light detecting section 42, for example, a metal layer at a bottom position, a middle position or a top position. By multiplexing the metal wiring layer of the optical sensing array 424 as a light blocking layer, it is beneficial to be able to reduce the thickness of the optical fingerprint device 40.

It should be noted that, in the embodiment of the present application, an optical sensing unit, and optical components (for example, the optical filter, the micro lens and the light blocking layer in fig. 6, or the optical filter and the one or more collimating holes in fig. 14) disposed thereon, and the micro prism may constitute an optical image capturing unit, which may be used to form one pixel of a captured image, and an array of a plurality of optical image capturing units constitutes the optical fingerprint device.

It is to be understood that in the embodiments of the present application, the at least one light-blocking layer may include only the first light-blocking layer, and in other embodiments, the at least one light-blocking layer may include the first light-blocking layer and the second light-blocking layer 414, and the second light-blocking layer 414 is used to avoid interference between adjacent optical image capturing units. In some embodiments, the second light-blocking layer 414 can be disposed between the microlens array and the first light-blocking layer; in other embodiments, the second light-blocking layer may also be disposed between adjacent microlenses or on the upper or lower surface of the optical filter. Alternatively, in some embodiments, the opening in the first light-blocking layer corresponding to the same microlens is smaller than the opening in the second light-blocking layer 414, for example, the opening 415a in the first light-blocking layer corresponding to the microlens 412a is larger than the opening 422a in the second light-blocking layer 421 corresponding to the microlens 412 a.

Further, in some embodiments, the optical fingerprint device 40 may further include a planarization layer 411 located above the microlens array 412, and an optical path layer 413 located below the microlens array 412. The planarization layer 411 and the light path layer 413 may be formed of a light transmitting material, and a second light blocking layer 414 formed of a light blocking material may be disposed within the light path layer 413.

Optionally, in some embodiments, the optical assembly may further include an optical filter 416, which may be fabricated at any position along an optical path from the reflected light formed by the reflection of the finger to the optical sensing array 424, which is not specifically limited in this embodiment. For example, the optical filter 416 may be disposed above the microlens array 412, or may be disposed below the microlens array 412, or above the optical sensing unit, etc. Alternatively, the filter 416 may be an infrared cut filter (IR cut filter).

The vertical light signal entering the filter reduces the loss of light signal compared to the oblique light signal passing directly through the filter 416, and the filter 416 need not be customized, thereby reducing its manufacturing complexity.

In the present embodiment, the optical filter 416 is used to reduce unwanted ambient light in the sensing of fingerprints to improve the optical sensing of the received light by the optical sensing array 424. The filter 416 may specifically be used to filter out light of a particular wavelength, e.g., near infrared light and portions of red light, etc. For example, a human finger absorbs most of the energy of light with a wavelength below 580nm, and if one or more optical filters or optical filter layers are designed to filter light with a wavelength from 580nm to infrared, the effect of ambient light on the optical detection in fingerprint sensing can be greatly reduced.

For example, the optical filter 416 may include one or more optical filters, which may be configured, for example, as a band pass filter to allow transmission of light emitted by the OLED screen while blocking other light components such as infrared light in sunlight. Such optical filtering may effectively reduce background light caused by sunlight when the optical fingerprint device 40 is used outdoors under a screen. The one or more optical filters may be implemented, for example, as optical filter coatings formed on one or more continuous interfaces, or may be implemented as one or more discrete interfaces. In addition, the light inlet surface of the optical filter 416 may be provided with an optical coating, so that the reflectivity of the light inlet surface of the optical filter is lower than a first threshold value, for example, 1%, thereby ensuring that the optical sensor array 424 can receive sufficient optical signals, and further improving the fingerprint identification effect.

In the example shown in FIG. 6, the microprism array 410 may only receive return from a finger at a particular angle

An incident optical signal (e.g., optical signal 43 shown in fig. 6). Take the second microprism 410b as an example, take an angle

The incident light signal 43 is converted into a vertical light signal after passing through the second micro prism 410 b. The vertical light signal passes through the optical filter 416 to filter out the light in the non-target wavelength band, and then passes through the second micro-lens 412b to be focused at the back focal point of the micro-lens 412b under the action of the micro-lens, i.e. focused in the fifth opening 422b corresponding to the second micro-lens 412b, and the light signal passing through the fifth opening 422b is received by the corresponding optical sensing unit 424 b. Because the light intensity of the light from the fingerprint valley is greater than that of the light from the fingerprint ridge, the electrical signal output by the optical sensing unit corresponding to the fingerprint valley is stronger, and the image is brighter; the electric signal output by the optical sensing unit corresponding to the fingerprint ridge is weak, the image is dark, and finally a clear fingerprint image with certain contrast is output.

Optionally, in some embodiments, the micro-prism may include at least one first incident surface, at least one first supporting surface, and at least one first exit surface, provided that the at least one first exit surface is parallel to the display screen, and the at least one first incident surface forms a second angle with the at least one first exit surface, so that the micro-prism can convert the first optical signal into the second optical signal. The operation principle of the microprisms will be described with reference to fig. 7, taking the second microprism 410b of the microprism array 410 shown in fig. 6 as an example.

Specifically, the second micro-prism 410b includes a first incident surface 501, a first exit surface 502, and a first supporting surface 500. When the incident light 51 reaches the first incident surface 501, part of the light is reflected to form reflected light 53, and the remaining part is refracted to form refracted light 52 and emitted from the first emission surface 502.

Assuming that the first optical signal forms a first included angle with a direction perpendicular to the display screen, the first included angle and a second included angle of the first incident surface and the second emergent surface may satisfy the following formula (1):

wherein theta represents the second included angle,

representing said first angle, n₁Representing the refractive index, n, of the propagation medium of the incident light 51₂Representing the refractive index of the microprisms.

Suppose that

The refractive index of the second microprism 410b is 1.56 and the incident light 51 is incident from air, i.e., n ₁1. The second included angle is 35.8 degrees as can be obtained by the above formula. That is, in the case where the refractive index of the micro-prism is 1.56 and the incident light is incident from the air, the second micro-prism 410b having the second included angle of 35.8 degrees may convert the first optical signal having the first included angle of 30 ° into the second optical signal that is vertically emitted.

From the above equation (1), the first angle is defined

In the fixed condition, by controlling the refractive index n of the second microprism₂The second angle theta of the second microprism can be controlled, for example, by setting the refractive index n of the microprism₂It is great, can make the second contained angle theta of microprism is less, that is to say, adopt the microprism of high refractive index material, be favorable to reducing the thickness of microprism, and then can reduce optical fingerprint device's whole thickness.

It should be noted that, since the optical signal reflected by the finger includes optical signals in various directions, the embodiment of the present application does not limit the specific value of the first included angle. The person skilled in the art can determine the angle of the second included angle formed by the incident surface and the exit surface of the micro-prisms in the micro-prism array 410 according to the angle of the oblique light signal reflected by the finger to be actually collected. Preferably, the first included angle is greater than or equal to 20 degrees. That is, the optical fingerprint device 40 can detect fingerprint information of a finger based on a large-angle oblique optical signal, thereby improving a fingerprint recognition effect.

Optionally, in this embodiment of the application, the micro-prism having the second included angle may be manufactured by a process such as nano-imprinting or gray scale lithography, which is mature and will not be described herein again.

In the above examples, the first supporting surface may be light-transmissive or may also be light-opaque, which is not limited in the embodiments of the present application.

In other embodiments, the micro-prism may include at least one first incident surface, at least one first supporting surface and at least one first emergent surface, the at least one supporting surface is provided with a reflective layer, wherein a first optical signal returned from a finger is incident on the first incident surface, enters the micro-prism to form a third optical signal, the third optical signal is incident on the first incident surface again after being reflected by the first supporting surface, and forms a second optical signal emergent perpendicularly after being reflected by the first incident surface again, that is, the reflective layer is used for causing the optical signal incident on the first supporting surface to undergo mirror reflection on the first supporting surface to form an optical signal emergent perpendicularly, the reflective layer may be a metal coating, such as a silver coating, an aluminum coating, and the like, and the micro-prism may be a teli-reul type prism.

It is assumed that the at least one first exit surface is parallel to the display screen and the at least one first entrance surface forms a second angle with the at least one first exit surface, so that the micro-prism can convert the first optical signal into the second optical signal. The operation principle of the microprisms will be described with reference to fig. 8, taking the second microprism 410b of the microprism array 410 shown in fig. 6 as an example.

Specifically, the second micro-prism 410b includes a first incident surface 501, a first exit surface 502, and a first supporting surface 505, and the first supporting surface 505 is provided with a reflective layer. When the incident light 51 reaches the first incident surface 501, part of the light is reflected to form reflected light 53, the remaining part is refracted to form refracted light 54 (i.e., a third optical signal), the refracted light 54 is specularly reflected on the first supporting surface 505, the reflected light 56 reaches the first incident surface 501 again, and at this time, the reflected light 56 forms reflected light 52 by total reflection because the angle between the reflected light 56 and the normal 503 of the first incident surface 501 is greater than the critical angle, and is emitted perpendicularly to the first emission surface 502.

In this embodiment, the incident light 51 forms a first angle with the direction perpendicular to the optical sensor

The first incident surface and the first exit surface form a second included angle θ, the refracted light 54 forms a third included angle α with the direction perpendicular to the first incident surface 501, the refracted light 54 forms a fourth included angle β with the direction parallel to the first exit surface 502, wherein the first included angle

The second angle θ, the third angle α, the fourth angle β, a refractive index n of a propagation medium of the first optical signal₁Refractive index n of the microprisms₂Satisfies the following formula (2):

hereinafter, a specific arrangement of the microprism array 410 according to the embodiments of the present application will be described with reference to fig. 9 to 13.

Alternatively, as an embodiment, as mode 1, the micro prism array 410 may include a plurality of micro prism units distributed in an array, each micro prism unit may include one micro prism, and one micro prism may correspond to one optical sensing unit, for example, the optical sensing unit may be disposed below an incident surface of the micro prism, so that the micro prism, and the optical assembly and the optical sensing unit disposed below the micro prism may constitute one optical image collecting unit.

Alternatively, as another embodiment, as mode 2, the micro-prism array 410 may include a plurality of micro-prism units distributed in an array, each micro-prism unit may include one micro-prism, and the one micro-prism may correspond to a plurality of optical sensing units, for example, each micro-prism may correspond to a row of optical sensing units or a column of optical sensing units in the optical sensing array, for example, the row or the column of optical sensing units may be disposed below an incident surface of the micro-prism. That is, the plurality of microprism units may include a row of microprisms or a column of microprisms distributed in an array, each microprism being elongated.

Fig. 9 may be a schematic perspective view of the microprism array 410 of fig. 6 implemented in mode 2. As shown in fig. 9, the micro-prism array 410 may include a row of micro-prisms, and a column of optical sensing units may be disposed below each micro-prism. That is, in fig. 6, the first, second, and third micro-prisms 410a, 410b, and 410c may be bar-shaped structures.

It should be understood that, in the embodiment of the present application, the number of the micro lenses disposed between the micro prisms and the optical sensing units is not limited, when one micro prism may correspond to one row of optical sensing units, one micro lens may be disposed below the one micro prism, the micro lens may also be in a strip structure, and corresponds to the one row of optical sensing units, in this case, the second optical signal converted by the micro prism reaches the one row of optical sensing units after being transmitted through the one micro lens; or, a row of microlenses may be disposed below the microprisms, each microlens corresponds to one optical sensing unit, and in this case, the second optical signal converted by the microprisms reaches the optical sensing unit corresponding to each microlens after being transmitted through the row of microlenses.

Fig. 10 is a top view of an optical fingerprint device 40 according to an embodiment of the present application. It should be understood that the number of the micro prisms and the micro lenses shown in the drawings are only examples, but the present application is not limited thereto.

Alternatively, as still another embodiment, as shown in mode 3, as shown in fig. 11, the micro prism array 410 may include a plurality of micro prism units 810 distributed in an array, and each micro prism unit 810 may include a plurality of micro prisms, and the plurality of micro prisms have a plurality of incident surfaces with different directions, and may be used for receiving optical signals returned via the finger from different directions. Optionally, projections of the plurality of micro prisms on the plane where the optical sensing unit is located may be in a quadrilateral shape, a pentagonal shape, or other shapes, which is not limited in this application. The projection area of each micro prism in the micro prism unit 810 on the plane where the optical sensing unit array 424 is located may be equal to or approximately equal to the projection area of each micro lens in the micro lens array on the plane where the optical sensing unit 424 is located, so as to improve the utilization rate of the micro prism unit 810 and reduce the volume of the optical fingerprint device 40.

Fig. 12 to 13 are schematic top views illustrating a microprism unit including four microprisms, and fig. 12 is a cross-sectional view of an optical fingerprint device along the direction of E-E', and it should be understood that one microprism unit is illustrated in the drawings, but the present application is not limited thereto.

Referring to fig. 12, the microprism unit 810 may include 4 microprisms, for example, the 4 microprisms are distributed in central symmetry. Further, one microlens may be disposed under each of the microprisms in each of the microprism units 810. At least one light blocking layer is arranged below each micro lens, an opening is formed in each light blocking layer, and an optical sensing unit is arranged below each opening.

It should be understood that in this embodiment, one microprism unit 810 and the optical components contained therebelow as well as the light detecting section 42 may be used to form one parent unit of the fingerprint sensing device 40. That is, each mother unit is composed of four sub-units (sub-unit a, sub-unit b, sub-unit c, and sub-unit d), each of which includes a first micro-prism 810a, a second micro-prism 810b, a third micro-prism 810c, a fourth micro-prism 810d, and a corresponding optical component and a light detection portion therebelow, each sub-unit may form one optical image capturing unit for forming one pixel of a captured image, and one mother unit may be used for forming four pixels of the captured image, that is, 2 rows × 2 columns of pixels.

As an example, the microprism unit 810 consisting of the first microprism 810a, the second microprism 810b, the third microprism 810c and the fourth microprism 810d may be constructed as a truncated pyramid. I.e., truncated pyramids, for example, the microprism units 810 consisting of the first microprism 810a, the second microprism 810b, the third microprism 810c and the fourth microprism 810d may be inscribed with a regular quadrangle to form the truncated pyramid, i.e., the top view of the microprism unit 810 may be the area enclosed by ABCD as shown in fig. 12. Alternatively, fig. 12 may be a top view of fig. 11 in the direction OA.

If a coordinate system is established with the lateral direction as the X axis and the longitudinal direction as the Y axis, the directions of the first microprism 810a, the second microprism 810b, the third microprism 810c and the fourth microprism 810d with respect to the origin O are different, for example, ∠ AOX ═ 135 °, ∠ BOX ═ 45 °, ∠ COX ═ 45 °, ∠ DOX ═ 135 °.

That is, the angles of two adjacent microprisms in the microprism unit 810 with respect to the origin O are different by 90 degrees. Thus, the microprism units 810 may be used to receive light from four different directions at an angle of incidence of

The light signals (light 831 and 832 in fig. 11 indicate two directions thereof) can effectively reduce the dependency on the finger placement angle in fingerprint authentication.

For example, the microprisms in the microprism unit array may be divided into multiple groups, each group of microprisms is configured to receive an optical signal in one direction, the optical sensing units in the optical sensing array are divided into multiple groups, each group of optical sensing units may be configured to receive an optical signal in one direction, each microprism in each group of microprisms may be configured to convert an optical signal in one direction into a vertical optical signal and transmit the vertical optical signal to a corresponding microlens, and further transmit the vertical optical signal to a corresponding group of optical sensing units through the microlens, and the optical signal received by the group of optical sensing units may be configured to generate a fingerprint image.

Therefore, in the embodiment of the application, the microprism units are arranged to receive optical signals at a plurality of angles, so that the exposure time of the optical sensing array can be reduced, the fingerprint identification time can be shortened, and the dependence of fingerprint acquisition on the incident light angle can be reduced.

Further, by receiving the optical signals of a plurality of angles by each micro-prism unit 810, the field of view of the fingerprint detection device 40 can be increased.

Fig. 14 is a side sectional view of the electronic device with the display screen taken along the direction E-E' shown in fig. 13.

Referring to fig. 14, the electronic device 60 may include a display 61 and a fingerprint detection device 40 under the display, wherein a micro-prism unit in the fingerprint detection device 40 may be used to receive light signals in 4 directions. For example, the third microprism 810c may be configured to receive optical signals in a second direction, i.e., the second field of view shown in the figure may be the field of view of the third microprism 810c, and similarly the first field of view shown in the figure may be the field of view of the first microprism 810 a. I.e. the fingerprint detection device 40 has a field of view in the direction E-E' which is the third field of view shown in the figure, which is larger than the first field of view and larger than the second field of view, effectively increasing the field of view of the fingerprint detection device 40.

It should be understood that the number of incidence surfaces of the micro prisms in the micro prism array 410 is not limited by the embodiments of the present application. For example, each of the plurality of microprisms comprises at least one incident surface, and at least one optical sensing unit is arranged under each incident surface of each of the plurality of microprisms; for another example, each of the plurality of microprisms includes a plurality of entrance faces that are axisymmetric or centrosymmetric.

It should also be understood that the embodiments of the present application do not limit the specific shape of the microprism array 410. For example, each of the plurality of microprisms is a triangular prism or a trapezoidal prism; for another example, each of the plurality of microprisms is a right-angle prism, and an incident surface of each of the plurality of microprisms is an inclined surface of the right-angle prism; as another example, each microprism in the array of microprisms 410 includes, but is not limited to, any of the following: right angle triangle prism, isosceles triangle prism, right angle trapezoidal prism and isosceles trapezoidal prism.

Optionally, the embodiment of the present application does not limit the specific structure of the optical assembly. For example, the optical assembly 132 shown in fig. 2 may be used. For example, the optical assembly may include a microlens array and a light blocking layer, and may also be a straight-hole collimator. For example, the straight hole collimator comprises a plurality of straight holes, wherein each optical sensing unit is configured to receive an optical signal transmitted via one or more straight holes. Further, the optical assembly may further include an optical filter.

Fig. 15 is a schematic cross-sectional view of an optical fingerprint device implemented with an optical assembly using a straight-hole collimator. As shown in fig. 15, the optical assembly is a straight hole collimator 911, the straight hole collimator 911 may be disposed between the microprism array 410 and the light detecting portion 42, the straight hole collimator 911 may include a plurality of collimating holes 912 arranged in a certain manner, and each optical sensing unit may correspond to one or more collimating holes 912. For example, each optical sensing unit may correspond to 3 collimating holes 912. Incident angle of

The light signal reflected by the finger is converted into a vertical light signal by the micro-prism array 410, and further transmitted to the optical sensor array 424 by the straight hole collimator 911. Incident angle of not

The optical signal reflected by the finger is blocked by the straight hole collimator 911, and thus cannot reach the optical sensor array 424.

Compared with the inclined hole collimator scheme shown in fig. 4, the microprism array 410 converts the optical signal which is returned by the finger and inclined relative to the display screen into a signal which is vertical to the display screen, and then the straight hole collimator 911 transmits the optical signal to the photoelectric sensing array, so that the manufacturing difficulty and cost of the collimator are effectively reduced.

In addition, since the angular screening capability of the straight hole collimator 911 is mainly determined by the aspect ratio (depth-to-aperture ratio) of the collimating hole 912, the straight hole with small aperture is favorable for improving the image resolution, but reduces the light input amount, so that the exposure time of the photo sensor array 424 needs to be prolonged. In the embodiment of the present application, a plurality of straight holes are disposed above each optical sensing unit, so that the exposure time of the optical sensing array 424 can be effectively reduced, and the user experience can be further improved.

It should be understood that fig. 15 is only an exemplary structure of the present application and should not limit the present application in any way.

For example, the optical sensing array 424 and the straight hole collimator 911 may be integrated. For example, the straight hole collimator 911 may be integrated into the light detection section 92, for example, by forming a collimating hole in the straight hole collimator 911 using a metal layer and a metal via layer in a later process.

In the above, the working principle of the angular conversion by the microprisms is explained with reference to fig. 6 to 15, and in some cases, if the incident angle of the optical signal returned from the finger is too large, for example, in the example shown in fig. 7,

the refractive index of the microprism is 40 degrees, and if the refractive index of the microprism is 1.5, the angle θ between the incident surface and the exit surface of the microprism is 41.2 degrees, in which case the angle between the incident light and the normal to the incident surface of the microprism is

I.e., 81.2 degrees, where about 43% of the incident light is reflected at the air/microprism interface, it is still necessary to extend the exposure time to compensate for the insufficient amount of light entering, increasing the fingerprintTime is identified, which affects user experience.

Based on the problem, further, in the embodiment of the present application, a transparent coating may be disposed on the incident surface of the incident light angle conversion structure, wherein the refractive index of the transparent coating is greater than the refractive index of the incident light angle conversion structure, so that the incident light is directly opposite to the first incident surface of the incident light angle conversion structure, thereby increasing the incident light amount entering the optical sensing array, and shortening the exposure time and the fingerprint identification time.

Hereinafter, referring to fig. 16 to 19, a specific description will be given by taking the incident light angle conversion structure as a micro prism array as an example, and when the incident light angle conversion structure is other structures, the implementation manner is similar, and details are not repeated here.

Fig. 17 to 19 are schematic cross-sectional views of an optical fingerprint device having a light transmissive coating provided on an incident light converting structure, and as shown in fig. 17 to 19, the light guiding part 41 may further include, in addition to the structure described in the foregoing embodiment: a light-transmitting coating 417 disposed on an incident surface of the incident light conversion structure, for example, if the incident light conversion structure is a micro prism array, the light-transmitting coating 417 is disposed on an incident surface of a micro prism in the micro prism array 410, and the light-transmitting coating 417 is configured to convert a first optical signal returned from a finger into a fourth optical signal, and further, the fourth optical signal is incident on an incident surface of a micro prism in the micro prism array 410 and is converted into a second optical signal emitted vertically by the micro prism array 410, where a refractive index of the light-transmitting coating 417 is greater than a refractive index of a material of the micro prism. The following description will take the incident light conversion structure as a micro prism array as an example to illustrate the specific implementation of the light-transmitting coating, but the application is not limited thereto. It should be understood that the specific description of each structural component in the optical fingerprint device shown in fig. 17 to 19 refers to the related description of the foregoing embodiments, and the detailed description is omitted here.

Therefore, in this application embodiment, through the printing opacity coating that sets up the high refracting index at the incident plane of microprism array, can make the first light signal that returns from the finger after twice refraction, convert the light signal of perpendicular outgoing into, can convert the direction of incident light on the one hand, make just right the light signal of the first incident plane of microprism array takes place the refraction and then converts into perpendicular light signal at this air/printing opacity coating interface, finally reachs the optical sensing array, and on the other hand adopts the printing opacity coating of high refracting index, under the condition of the same incident angle, the contained angle of required incident plane and the emergent plane of microprism is littleer, is favorable to reducing the thickness of microprism, and then reduces optical fingerprint device's whole thickness.

It should be understood that the thickness, shape, etc. of the light-transmitting coating layer are not limited in the embodiments of the present application, as long as the light-transmitting coating layer can cooperate with the micro-prism array to convert the first optical signal into the second optical signal emitted vertically.

Optionally, in some embodiments, a light transmissive coating may be disposed on each of the microprisms in the microlens array 410. Specifically, the light transmissive coating 417 may be disposed on an incident surface of the microprisms. For example, the light transmissive coating 417 has at least one second entrance face, at least a second exit face and at least one second support face, the second exit face being parallel to the first entrance face of the microprisms. Hereinafter, a specific operation principle of the light-transmissive coating will be described by taking the light-transmissive coating 417b on the microprism 410b as an example with reference to fig. 16.

Specifically, the light-transmissive coating 417b may have a second incident surface 504, a second exit surface 501 (i.e., an incident surface of the micro-prism), and a second supporting surface 500, and the second incident surface 504 may be parallel to the direction of the display screen, or parallel to an exit surface of the micro-prism. Alternatively, the light-transmissive coating 417b may be grown by coating (e.g., spinning, spraying, etc.) to obtain the light-transmissive coating of the above-described structure.

Incident light 51 returning from the finger is incident on the second incident surface 504 of the light-transmissive coating 417b, part of the light is reflected to form reflected light 53, the other light is refracted at the air/light-transmissive coating interface to form refracted light 54, further, the refracted light 54 is refracted for the second time at the light-transmissive coating/micro-prism interface and finally exits from the first exit surface 502 of the micro-prism, if the refracted light 52 is to be emitted perpendicularly, whereinThe incident light 51 forms a first angle with the direction perpendicular to the second incident surface 504

The first incident surface 501 and the first exit surface 502 form a second included angle θ, the refracted light 54 forms a third included angle α with the direction perpendicular to the first incident surface 501, wherein the refractive index n of the light-transmitting coating layer is equal to or greater than the first included angle, the second included angle, the third included angle, and the refractive index n of the light-transmitting coating layer₀The refractive index n of the propagation medium of said incident light 51₁And refractive index n of the microprisms₂Satisfies the following formula (3):

n₁sinα＝n₂sin θ equation (3).

In this embodiment, if

Degree, incident light 51 is incident from air, i.e. n₁When the refractive index of the high refractive index light transmissive coating layer is 2 and the refractive index of the material of the micro lens is 1.3, the included angle θ of the micro prism can be determined to be 38.2.

It should be understood that in the embodiment of the present application, the second incident surface of the light-transmissive coating is parallel to the first exit surface of the micro-prism, and the second incident surface of the light-transmissive coating is substantially parallel or approximately parallel to the first exit surface of the micro-prism, and correspondingly, the refracted light 54 may exit from the first exit surface of the micro-prism approximately perpendicularly or substantially perpendicularly.

Optionally, in this embodiment, the second incident surface of the transparent coating 417 may be disposed flush with, slightly above, or slightly below the plane where the highest point of the supporting surface of the micro prism is located, that is, the transparent coating disposed on the first incident surface of the micro prism has little influence on the overall thickness of the module.

It should be understood that, in the optical fingerprint device using the transparent coating shown in fig. 16, since the incident surface of the transparent coating is parallel to the display screen, the transparent coating corresponding to each micro prism can be uniformly prepared on the incident surface of the micro prism array after the micro prism array is prepared, which can reduce the complexity of the preparation process.

Alternatively, in this embodiment, the light-transmitting coating layer may be formed by filling an organic material with a high-refractive-index inorganic material, for example, zirconia or other inorganic materials.

In order to further reduce the reflectivity of the surface of the light-transmitting coating, an anti-reflection coating can be arranged on the incident surface of the light-transmitting coating, so that the light loss of the surface of the light-transmitting coating can be further reduced, and most of light signals can be refracted to enter the light-transmitting coating and then enter the micro-prism array.

Optionally, in some embodiments, the anti-reflective coating may be an anti-reflective coating, which increases the transmittance of the optical signal and decreases the reflectance of the optical signal.

Through the printing opacity coating that sets up the high refracting index at the incident plane of microprism array, can make the incident light take place twice refraction in this printing opacity coating and microprism, and then from the vertical outgoing of microprism's exit face, under the condition of same incident angle, set up the printing opacity coating of high refracting index, be favorable to reducing the contained angle of required microprism's incident plane and exit face, thereby can reduce the thickness of module, and the printing opacity coating that sets up the high refracting index on microprism can reduce the reflectivity on microprism surface, reduce the light loss, thereby can shorten when the exposure, promote fingerprint identification speed.

It should be appreciated that the optical fingerprint device shown in fig. 16 to 19 may receive the light signal incident directly to the incident surface of the micro prism, which is advantageous to increase the light receiving area of the optical fingerprint device, relative to the optical fingerprint device shown in fig. 6, 11 and 15, where the light receiving area may be the area of the optical fingerprint device receiving the light signal. For example, for the optical fingerprint device shown in fig. 6, when the incident light is 30 °, the light receiving area of a single micro prism is 58.4% of the base area of the micro prism, and when the optical fingerprint device described in fig. 16 is adopted as the optical path, for the same incident angle, in the case that the refractive index of the light-transmitting coating is 2, the light receiving area of a single micro prism is 1.34 times of the base area of the micro prism, which is about 2.29 times of the light receiving area of the optical fingerprint device shown in fig. 6, which is beneficial to increasing the signal quantity of the optical signal received by the optical sensor, thereby being capable of shortening the exposure time and increasing the fingerprint identification speed.

It will be appreciated that the microprismatic structure of figure 8, without the light transmissive coating, also has a higher light-receiving area relative to the microprismatic structure of figure 7, and thus, for high angle incident light, for example

Greater than 45 degrees, the microprism still can be effectual carries out the receipt of incident light, consequently, adopts the microprism structure shown in fig. 8 can not set up the printing opacity coating, in other embodiments, also can set up the printing opacity coating above the microprism structure shown in fig. 8, further promotes and receives the light area, shortens exposure time, promotes fingerprint identification speed.

It should be noted that the thickness of the transparent coating in fig. 16 to 19 is only for convenience of describing the optical path transmission in the transparent coating, and in an actual product, the thickness of the transparent coating is very thin, and has little influence on the thickness of the optical fingerprint device.

The embodiment of the present application also provides an electronic device, as shown in fig. 20, the electronic device 700 may include a display 710 and an optical fingerprint device 720, where the optical fingerprint device 720 is disposed below the display 710.

Optionally, the optical fingerprint device 720 may be the optical fingerprint device 40 in the foregoing embodiment, and the specific structure may refer to the related description, which is not described herein again.

Alternatively, in one embodiment of the present application, the display screen 710 may be embodied as a self-luminous display screen (such as an OLED display screen) and includes a plurality of self-luminous display units (such as OLED pixels or OLED light sources). When the optical image acquisition system is a biometric identification system, a part of the self-luminous display units in the display screen can be used as an excitation light source for biometric identification of the biometric identification system, and is used for emitting optical signals to the biometric detection area for biometric detection.

It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application and are not intended to limit the scope of the embodiments of the present application.

It is to be understood that the terminology used in the embodiments of the present application and the appended claims is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application. For example, as used in the examples of this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Those of ordinary skill in the art will appreciate that the elements of the examples described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described above generally in terms of their functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed system and apparatus may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present application.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially or partially contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

While the invention has been described with reference to specific embodiments, the scope of the invention is not limited thereto, and those skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An optical fingerprint device, for being disposed below a display screen of an electronic device, comprising:

the incident angle conversion structure is arranged below the display screen and used for converting a first optical signal returned from a finger above the display screen into a second optical signal, wherein the first optical signal is an optical signal inclined relative to the display screen, and the second optical signal is an optical signal vertical relative to the display screen;

the optical assembly is arranged below the incidence angle conversion structure and used for receiving the second optical signal and transmitting the second optical signal to the optical sensor;

the optical sensor comprises a plurality of optical sensing units, is arranged below the optical assembly and is used for receiving optical signals transmitted by the optical assembly, and the optical signals are used for acquiring fingerprint information of the finger.

2. The optical fingerprint device of claim 1, wherein the incident angle conversion structure comprises a microprism array comprising a plurality of microprism units, each microprism unit comprising at least one microprism, each microprism comprising at least one first entrance face and at least one first exit face, the first entrance face being tilted with respect to the plane of the display screen and the first exit face being parallel to the plane of the display screen.

3. The optical fingerprint device according to claim 2, wherein each micro prism unit comprises a micro prism, and an optical sensing unit or a row of optical sensing units is arranged below one micro prism; or

4. The optical fingerprint device of claim 3, wherein the incidence surfaces of the plurality of microprisms are oriented in different directions relative to the plane of the optical sensor.

5. The optical fingerprint device of claim 4, wherein the plurality of microprisms comprises four microprisms, wherein the incident surfaces of adjacent ones of the four microprisms are angularly displaced by 90 degrees relative to the orientation of the optical sensor.

6. The optical fingerprint device of any one of claims 2 to 5, wherein the first light signal forms a first angle with a direction perpendicular to the optical sensor

The first incident surface and the first emergent surface of each micro prism form a second included angle theta, wherein the first included angle theta

7. the optical fingerprint device of any one of claims 2 to 5, wherein each microprism comprises at least one first supporting surface provided with a reflective layer.

8. The optical fingerprint device of claim 7, wherein the first optical signal is incident on the first incident surface, enters the microprisms to form a third optical signal, and the third optical signal is reflected by the first supporting surface and then re-incident on the first incident surface, and is re-reflected by the first incident surface to form the second optical signal that is vertically emittedWherein the first optical signal forms a first angle with a direction perpendicular to the optical sensor

β (90 ° - θ) ten α

θ＝(90°-θ)。

9. The optical fingerprint device of any one of claims 1 to 8, further comprising:

10. The optical fingerprint device of claim 9, wherein the second exit surface is parallel to the incident surface of the incident light conversion structure, and the second incident surface is parallel to the incident surface of the incident light conversion structureThe surface is parallel to the emergent surface of the incident light conversion structure, and the first optical signal forms a first included angle with the direction perpendicular to the second incident surface

n_tsinα＝n₂sinθ。

11. the optical fingerprint device of claim 9 or 10, wherein the light-transmissive coating is formed on the incident surface of the incident light conversion structure by spin coating or spray coating.

12. The optical fingerprint device according to any one of claims 9 to 11, wherein the at least one second entrance face of the light transmissive coating is provided with an anti-reflection coating for reducing the reflectivity of the first light signal at the at least one second entrance face and/or a polarization coating for selecting the polarization direction of the first light signal.

13. The optical fingerprint device according to any one of claims 1 to 12, wherein the optical assembly comprises at least one light blocking layer and a microlens array, the at least one light blocking layer is disposed below the microlenses, and each of the at least one light blocking layer is provided with an aperture therein;

14. The optical fingerprint device of claim 13, wherein the at least one light blocking layer comprises a first light blocking layer disposed at a back focal plane location of the microlens array.

15. The optical fingerprint device of claim 14, wherein the first light blocking layer is a metal layer of the optical sensor.

16. The optical fingerprint device of any one of claims 13 to 15, wherein the optical assembly further comprises:

an optical filter provided in at least one of the following positions:

the incident angle conversion structure and the micro lens array;

between the microlens array and the optical sensor.

17. The optical fingerprint device of any one of claims 1 to 12, wherein the optical assembly comprises a straight hole collimator comprising a plurality of straight holes, and each optical sensing unit in the optical sensor corresponds to at least one straight hole in the straight hole collimator, wherein the straight hole collimator is configured to receive the second optical signal converted by the incident light conversion structure and transmit the second optical signal to the plurality of optical sensing units through the straight holes in the straight hole collimator.

18. The optical fingerprint device of claim 17, wherein the straight hole collimating unit is formed by a metal layer and a metal via layer of the optical sensing unit.

19. The optical fingerprint device of claim 17 or 18, wherein the optical assembly further comprises:

an optical filter provided in at least one of the following positions:

the incident angle conversion structure and the straight hole collimator;

the straight hole collimator and the optical sensing unit.

20. The optical fingerprint device according to any one of claims 1 to 19, wherein the display screen is an Organic Light Emitting Diode (OLED) display screen, and the optical fingerprint device utilizes a part of the display unit of the OLED display screen as an excitation light source for optical fingerprint detection.

21. An electronic device, comprising:

a display screen;

the optical fingerprint device of any one of claims 1 to 20, wherein the optical fingerprint device is disposed below the display screen.

22. The electronic device of claim 21, wherein the display screen is an Organic Light Emitting Diode (OLED) display screen comprising a plurality of OLED light sources, and wherein the optical fingerprint device employs at least some of the OLED light sources as excitation light sources for optical fingerprint detection.