CN211319244U

CN211319244U - Fingerprint detection device and electronic equipment

Info

Publication number: CN211319244U
Application number: CN202020142210.5U
Authority: CN
Inventors: 王炳文; 池文明; 王磊
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2020-08-21
Anticipated expiration: 2030-01-22

Abstract

The embodiment of the application provides a fingerprint detection device and electronic equipment, and the performance of fingerprint identification can be improved. This fingerprint detection's device is applicable to the below of display screen in order to realize optical fingerprint detection under the screen, the display screen includes fingerprint detection area, fingerprint detection area includes first region and second area, the second area encircles first region, the device includes: an optical path guiding structure for guiding a first return light signal formed by a finger above the display screen to an optical sensor, wherein the first return light signal is a light signal in which pixels in the first area do not emit light, and light emitted by pixels in the second area is transmitted into the finger, and then transmitted out of the finger and through the display screen; an optical sensor disposed below the optical path guide structure for receiving the first return light signal passing through the optical path guide structure, the first return light signal being used to acquire a fingerprint image of the finger.

Description

Fingerprint detection device and electronic equipment

Technical Field

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

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.

The current technology of fingerprint under optical screen is basically applied to the screen of a mobile phone with self-luminous organic light-Emitting Diode (OLED), and the self-luminous screen pixels included in the screen are used as a light source, so that light rays irradiate to fingers, are reflected by the fingers, penetrate through the screen of the mobile phone and a special optical lens, and are received by a sensor under the screen, and fingerprint image collection and fingerprint identification are realized. This method has some disadvantages, such as difficulty in identifying wet fingers and inability to counterfeit 2D fake fingers.

SUMMERY OF THE UTILITY MODEL

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

In a first aspect, a fingerprint detection apparatus is provided, which is suitable for below a display screen to realize optical fingerprint detection under the display screen, where the display screen includes a fingerprint detection area, the fingerprint detection area includes a first area and a second area, the second area surrounds the first area, and the fingerprint detection apparatus includes: an optical path guiding structure for guiding a first return light signal formed by a finger above the display screen to an optical sensor, wherein the first return light signal is a light signal in which pixels in the first area do not emit light, and light emitted by pixels in the second area is transmitted into the finger, and then transmitted out of the finger and through the display screen; an optical sensor disposed below the optical path guide structure for receiving the first return light signal passing through the optical path guide structure, the first return light signal being used to acquire a fingerprint image of the finger.

In the technical scheme of the embodiment of the application, the pixels in the first area of the fingerprint detection area do not emit light, the light emitted by the pixels in the second area is transmitted into the finger and then transmitted out from the finger and passes through the display screen, the transmitted light passing through the finger is detected to obtain the fingerprint pattern of the finger, the imaging quality is higher, the identification capability of a wet finger can be improved, and the anti-counterfeiting effect can be realized on the 2D fake finger. Therefore, the technical scheme can improve the performance of fingerprint identification.

In one possible implementation, the size of the first area is not smaller than the diameter of the field of view of the fingerprint sensor.

In a possible implementation manner, the vertical projection area of the first region coincides with the vertical projection area of the field of view of the fingerprint sensor, or the vertical projection area of the first region covers the vertical projection area of the field of view of the fingerprint sensor.

In one possible implementation, the size L of the first area satisfies:

D≤L≤D+2×d×tanα

wherein D is a field diameter of the optical sensor, D is a distance from the pixel in the second region to the upper surface of the display screen, and a represents a light emitting angle of the pixel.

In one possible implementation, the first region has a circular or square shape, and the boundary of the second region has a circular or square shape.

In one possible implementation, the combined shape of the first region and the second region is concentric circles.

In one possible implementation, the light emitted by the pixels in the second region is red or yellow.

In one possible implementation, the apparatus further includes: and the optical filter is positioned above the optical fingerprint sensor and used for filtering other optical signals except the first return optical signal.

In a possible implementation manner, the wavelength range of the first return light signal is 600-660 nm, and the optical filter is used for filtering out light with a wavelength not equal to 600-660 nm.

In one possible implementation, the optical path guiding structure includes an optical lens disposed above the optical fingerprint sensor for converging the first return optical signal passing through the display screen to a sensing array of the optical fingerprint sensor.

In a possible implementation manner, the optical path guiding structure includes a microlens array having a plurality of microlenses and a light blocking layer having a plurality of micro-holes, and the microlens array is configured to focus the first return optical signal passing through the display screen to the corresponding micro-holes of the light blocking layer through the plurality of microlenses respectively, and transmit the first return optical signal to the corresponding optical sensing units in the sensing array of the optical fingerprint sensor through the micro-holes.

In one possible implementation, the light intensity of the first return light signal received by the optical sensor is used to determine whether the finger is a real finger.

In a possible implementation manner, if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, the finger is a real finger; and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, the finger is a fake finger.

According to the technical scheme, not only can wet fingers be identified, but also whether the fingers are real fingers or not can be determined according to the received light intensity of the first light signal.

In a second aspect, an electronic device is provided, which includes the apparatus for fingerprint detection as in the first aspect or any possible implementation manner of the first aspect, where the apparatus is disposed below the display screen to implement an off-screen optical fingerprint detection.

In one possible implementation, the electronic device further includes: and the processor is used for determining whether the finger is a real finger or not according to the light intensity of the first return light signal received by the optical sensor.

In one possible implementation, the processor is specifically configured to: if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, determining that the finger is a true finger; and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, determining that the finger is a fake finger.

Drawings

Fig. 1 is a schematic configuration diagram of an electronic apparatus to which the present application can be applied.

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

Fig. 3 is another schematic block diagram of an electronic device to which the present application may be applied.

Fig. 4 is a schematic cross-sectional view of the electronic device shown in fig. 3.

FIG. 5 is a schematic diagram of a model for imaging a fingerprint from reflected light after a finger is illuminated by a light source.

Fig. 6 is a reflected light fingerprint image of a normal finger.

Fig. 7 is a reflected light fingerprint image of a wet finger.

FIG. 8 is a model schematic of fingerprint imaging from transmitted light after a light source illuminates the finger.

Fig. 9 is a transmitted light fingerprint image of a normal finger.

Figure 10 is a transmitted light fingerprint image of a wet finger.

Fig. 11 is a schematic side view of an electronic device according to an embodiment of the present application during fingerprint detection.

Fig. 12 is a schematic front view of an electronic device of an embodiment of the present application.

FIG. 13 is a cross-sectional view of the dimensions of different areas in the fingerprint detection area.

Fig. 14(a) to 14(d) are schematic combined shapes of the first region and the second region in the fingerprint detection region.

FIG. 15 is a schematic diagram of fingerprint recognition of a 2D fake finger on an electronic device according to an embodiment of the present application.

Detailed Description

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

The technical scheme of the embodiment of the application can be applied to various electronic devices. Such as portable or mobile computing devices, e.g., smart phones, laptops, tablets, gaming devices, etc., and other electronic devices, e.g., electronic databases, automobiles, Automated Teller Machines (ATMs), etc. However, the present embodiment is not limited thereto.

The technical scheme of the embodiment of the application can be used for the biological feature recognition technology. The biometric technology includes, but is not limited to, fingerprint recognition, palm print recognition, iris recognition, face recognition, and living body recognition. For convenience of explanation, the fingerprint identification technology is described as an example below.

The technical scheme of the embodiment of the application can be used for the under-screen fingerprint identification technology and the in-screen fingerprint identification technology.

Fingerprint identification technique is installed in the display screen below with fingerprint identification module under the screen to realize carrying out the fingerprint identification operation in the display area of display screen, need not set up the fingerprint collection region in the positive region except that the display area of electronic equipment. Specifically, the fingerprint identification module uses the light that returns from the top surface of electronic equipment's display module to carry out fingerprint response and other response operations. This returned light carries information about objects (e.g., fingers) in contact with or in proximity to the top surface of the display assembly, and the fingerprint recognition module located below the display assembly performs underscreen fingerprint recognition by capturing and detecting this returned light. The fingerprint identification module can be designed to realize desired optical imaging by properly configuring an optical element for collecting and detecting returned light, so as to detect fingerprint information of the finger.

Correspondingly, (In-display) fingerprint identification technique means installs inside the display screen fingerprint identification module or partial fingerprint identification module In the screen to realize carrying out the fingerprint identification operation In the display area of display screen, need not set up the fingerprint collection region In the positive region except that the display area of electronic equipment.

Fig. 1 to 4 are schematic views showing an electronic device to which the embodiment of the present application can be applied. Fig. 1 and 3 are schematic orientation diagrams of the electronic device 10, and fig. 2 and 4 are schematic cross-sectional diagrams of the electronic device 10 shown in fig. 1 and 3, respectively.

Referring to fig. 1 to 4, the electronic device 10 may include a display 120 and an optical fingerprint identification module 130.

The display 120 may be a self-luminous display employing display units having self-luminous properties as display pixels. For example, the display screen 120 may be an Organic Light-Emitting Diode (OLED) display screen or a Micro-LED (Micro-LED) display screen. In other alternative embodiments, the Display 120 may also be a Liquid Crystal Display (LCD) or other passive light emitting Display, which is not limited in this embodiment of the present application. Further, the display screen 120 may also be specifically a touch display screen, which not only can perform image display, but also can detect a touch or pressing operation of a user, thereby providing a human-computer interaction interface for the user. For example, in one embodiment, the electronic device 10 may include a Touch sensor, which may be embodied as a Touch Panel (TP), which may be disposed on a surface of the display screen 120, or may be partially or wholly integrated within the display screen 120, thereby forming the Touch display screen.

Optical fingerprint module 130 includes an optical fingerprint sensor that includes a sensing array 133 having a plurality of optical sensing elements 131 (which may also be referred to as optical sensing pixels, light sensing pixels, pixel cells, etc.). The sensing array 133 is located in an area or a sensing area thereof, which is the fingerprint detection area 103 (also called a fingerprint collection area, a fingerprint identification area, etc.) of the optical fingerprint module 130.

Wherein, the optical fingerprint module 130 is disposed in a local area below the display screen 120.

With continued reference to fig. 1, the fingerprint detection area 103 may be located within a display area of the display screen 120. In an alternative embodiment, the optical fingerprint module 130 may be disposed at other positions, such as the side of the display screen 120 or the edge opaque area of the electronic device 10, and the optical path is designed to guide the optical signal from at least a part of the display area of the display screen 120 to the optical fingerprint module 130, so that the fingerprint detection area 103 is actually located in the display area of the display screen 120.

For the electronic device 10, when a user needs to unlock or perform other fingerprint verification on the electronic device 10, 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.

With continued reference to fig. 2, the optical fingerprint module 130 may include a light detection portion 134 and an optical assembly 132. The light detecting portion 134 includes the sensing array 133 (also referred to as an optical fingerprint sensor) and a reading circuit and other auxiliary circuits electrically connected to the sensing array 133, which can be fabricated on a chip (Die) by a semiconductor process, such as an optical imaging chip or an optical fingerprint sensor. The sensing array 133 is specifically a 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 133 of the light detecting portion 134, and may specifically include a Filter (Filter) for filtering out ambient light penetrating through the finger, a light guiding layer or a light path guiding structure for guiding reflected light reflected from the surface of the finger to the sensing array 133 for optical detection, and other optical elements.

In some embodiments of the present application, 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.

In some embodiments of the present application, the area or the light sensing range of the sensing array 133 of the optical fingerprint module 130 corresponds to the fingerprint detection area 103 of the optical fingerprint module 130. The fingerprint collecting area 103 of the optical fingerprint module 130 may be equal to or not equal to an area or a light sensing range of an area where the sensing array 133 of the optical fingerprint module 130 is located, which is not specifically limited in the embodiment of the present application.

For example, the light path is guided by the light collimation method, and the fingerprint detection area 103 of the optical fingerprint module 130 may be designed to be substantially consistent with the area of the sensing array of the optical fingerprint module 130.

For another example, for example, through a light path design such as lens imaging, a reflective folded light path design, or other light path designs such as light convergence or reflection, the area of the fingerprint detection area 103 of the optical fingerprint module 130 may be larger than the area of the sensing array 133 of the optical fingerprint module 130.

The following is an exemplary description of the optical path guiding structure that the optical component 132 may include.

Taking the optical Collimator with the through hole array having the high aspect ratio as an example, the optical Collimator may specifically be a Collimator (collimater) layer made of a semiconductor silicon wafer, and the optical Collimator has a plurality of collimating units or micropores, the collimating units may specifically be small holes, in reflected light reflected from a finger, light perpendicularly incident to the collimating units may pass through and be received by sensor chips below the collimating units, and light with an excessively large incident angle is attenuated by multiple reflections inside the collimating units, so that each sensor chip can basically only receive reflected light reflected from fingerprint lines directly above the sensor chip, and image resolution can be effectively improved, and fingerprint identification effect is improved.

Taking the optical path design of the optical Lens adopted by the optical path guiding structure as an example, the optical path guiding structure may 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 for converging the reflected light reflected from the finger to the sensing array 133 of the light detection portion 134 therebelow, so that the sensing array 133 may perform imaging based on the reflected light, thereby obtaining the fingerprint image of the finger. Further, the optical lens layer may further be formed with a pinhole or a micropore diaphragm in the optical path of the lens unit, for example, one or more light-shielding sheets may be formed in the optical path of the lens unit, wherein at least one light-shielding sheet may be formed with a light-transmitting micropore in the optical axis or the optical central region of the lens unit, and the light-transmitting micropore may serve as the pinhole or the micropore diaphragm. The pinhole or the micro-aperture diaphragm can cooperate with the optical lens layer and/or other optical film layers above the optical lens layer to enlarge the field of view of the optical fingerprint module 130, so as to improve the fingerprint imaging effect of the optical fingerprint module 130.

Taking the optical path design in which the optical path guiding structure employs a Micro-Lens (Micro-Lens) layer as an example, the optical path guiding structure may be a Micro-Lens array including a plurality of Micro-lenses, which may be formed above the sensing array 133 of the light detecting portion 134 through a semiconductor growth process or other processes, and each of the Micro-lenses may respectively correspond to one of the sensing units of the sensing array 133. And other optical film layers, such as a dielectric layer or a passivation layer, can be formed between the microlens layer and the sensing unit. More specifically, a light blocking layer (or referred to as a light shielding layer, a light blocking layer, etc.) having micro holes (or referred to as open holes) may be further included between the microlens layer and the sensing unit, wherein the micro holes are formed between the corresponding microlenses and the sensing unit, and the light blocking layer may block optical interference between adjacent microlenses and the sensing unit, and enable light corresponding to the sensing unit to be converged into 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 of the implementations described above for the optical path directing structure may be used alone or in combination.

For example, a microlens layer may be further disposed above or below the collimator layer or the optical lens layer. Of course, when the collimator layer or the optical lens layer is used in combination with the microlens layer, the specific lamination structure or optical path thereof may need to be adjusted according to actual needs.

On the other hand, the optical assembly 132 may further include other optical elements, such as a Filter (Filter) or other optical film, which may be disposed between the optical path guiding structure and the optical fingerprint sensor or between the display screen 120 and the optical path guiding structure, and mainly used for isolating the influence of external interference light on the optical fingerprint detection. The filter layer may be configured to filter ambient light that penetrates through a finger and enters the optical fingerprint sensor through the display screen 120, and similar to the optical path guiding structure, the filter layer may be respectively disposed for each optical fingerprint sensor to filter interference light, or may also cover the plurality of optical fingerprint sensors simultaneously with one large-area filter layer.

Fingerprint identification module 130 may be configured to collect fingerprint information (e.g., fingerprint image information) of a user.

Taking the display screen 120 as an example, the display screen has a self-luminous display unit, such as an Organic Light-Emitting Diode (OLED) display screen or a Micro-LED (Micro-LED) display screen. The optical fingerprint module 130 may use a display unit (i.e., an 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 the finger 140 is pressed against the fingerprint detection area 103, the display 120 emits a beam of light 111 towards the target finger 140 above the fingerprint detection area 103, and the light 111 is reflected at the surface of the finger 140 to form reflected light or scattered light (transmitted light) is formed by scattering through the inside of the finger 140. In the related patent application, the above-mentioned reflected light and scattered light are collectively referred to as reflected light for convenience of description. Because the ridges (ridges) 141 and the valleys (valley)142 of the fingerprint have different light reflection capabilities, the reflected light 151 from the ridges and the reflected light 152 from the valleys of the fingerprint have different light intensities, and after passing through the optical assembly 132, the reflected light is received by the sensing array 133 in the optical fingerprint module 130 and converted into corresponding electrical signals, i.e., fingerprint detection signals; 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 alternatives, the optical fingerprint module 130 may also use an internal light source or an external light source to provide an optical signal for fingerprint detection and identification. In this case, the optical fingerprint module 130 may be applied to not only a self-luminous display screen such as an OLED display screen, but also a non-self-luminous display screen such as a liquid crystal display screen or other passive luminous display screens.

Taking an application to a liquid crystal display screen with a backlight module and a liquid crystal panel as an example, to support the underscreen fingerprint detection of the liquid crystal display screen, the optical fingerprint system of the electronic 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 screen or in an edge area below a protective cover plate of the electronic device 10, and the optical fingerprint module 130 may be disposed below the edge area of the liquid crystal panel or the protective cover plate and guided through a light path so that the fingerprint detection light may reach the optical fingerprint module 130; alternatively, the optical fingerprint module 130 may be disposed below the backlight module, and the backlight module may open holes or perform other optical designs on film layers such as a diffusion sheet, a brightness enhancement sheet, and a reflection sheet to allow the fingerprint detection light to pass through the liquid crystal panel and the backlight module and reach the optical fingerprint module 130. When the optical fingerprint module 130 is used to provide an optical signal for fingerprint detection by using an internal light source or an external light source, the detection principle is consistent with the above description.

In a specific implementation, the electronic device 10 may further include a transparent protective cover, which may be a glass cover or a sapphire cover, located above the display screen 120 and covering the front surface of the electronic device 10. Therefore, in the embodiment of the present application, 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, optics fingerprint module 130 can only include an optics fingerprint sensor, and the area of the fingerprint detection area 103 of optics fingerprint module 130 is less and the rigidity this moment, therefore the user need press the finger to the specific position of fingerprint detection area 103 when carrying out the fingerprint input, otherwise optics fingerprint module 130 probably can't gather the fingerprint image and cause user experience not good. In other alternative embodiments, the optical fingerprint module 130 may specifically include a plurality of optical fingerprint sensors. A plurality of optics fingerprint sensor can set up side by side through the concatenation mode the below of display screen 120, just a plurality of optics fingerprint sensor's response area constitutes jointly optics fingerprint module 130's fingerprint detection area 103. Thereby the fingerprint detection area 103 of optical fingerprint module 130 can extend to the main area of the lower half of display screen, extend to the finger and press the region conventionally promptly to realize blind formula fingerprint input operation of pressing. Further, when the number of the optical fingerprint sensors is sufficient, the fingerprint detection area 103 may also be extended to a half display area or even the entire display area, thereby realizing half-screen or full-screen fingerprint detection.

Referring to fig. 3 and 4, the optical fingerprint module 130 in the electronic device 10 may include a plurality of optical fingerprint sensors, the plurality of optical fingerprint sensors may be arranged below the display screen 120 side by side in a manner such as splicing, and sensing areas of the plurality of optical fingerprint sensors jointly form the fingerprint detection area 103 of the optical fingerprint device 130.

Further, the optical assembly 132 may include a plurality of optical path guiding structures, each of which corresponds to one optical fingerprint sensor (i.e., the sensing array 133) and is attached above the corresponding optical fingerprint sensor. Alternatively, the plurality of optical fingerprint sensors may share an integral optical path directing structure, i.e. the optical path directing structure has an area large enough to cover the sensing array of the plurality of optical fingerprint sensors.

Taking the optical collimator with the through hole array having the aspect ratio as an example of the optical assembly 132, when the optical fingerprint module 130 includes a plurality of optical fingerprint sensors, one or more collimating units may be configured for one optical sensing unit in the optical sensing array of each optical fingerprint sensor, and the collimating units are attached to and disposed above the corresponding optical sensing units. Of course, the plurality of optical sensing units may also share one collimating unit, i.e. the one collimating unit has a sufficiently large aperture to cover the plurality of optical sensing units. Because a collimation unit can correspond a plurality of optical sensing units or an optical sensing unit corresponds a plurality of collimation units, the spatial period of display screen 120 and optical fingerprint sensor's spatial period's correspondence has been destroyed, therefore, even the spatial structure of the luminous display array of display screen 120 and optical fingerprint sensor's optical sensing array's spatial structure are similar, also can effectively avoid optical fingerprint module 130 to utilize the optical signal through display screen 120 to carry out fingerprint imaging and generate moire fringe, optical fingerprint module 130's fingerprint identification effect has effectively been improved.

Taking the optical lens as an example of the optical component 132, when the optical fingerprint module 130 includes a plurality of sensor chips, an optical lens may be configured for each sensor chip to perform fingerprint imaging, or an optical lens may be configured for a plurality of sensor chips to implement light convergence and fingerprint imaging. Even when one sensor chip has two sensing arrays (Dual Array) or multiple sensing arrays (Multi-Array), two or more optical lenses can be configured for the sensor chip to cooperate with the two or more sensing arrays for optical imaging, so as to reduce the imaging distance and enhance the imaging effect.

It should be understood that fig. 1-4 are only examples of the present application and should not be construed as limiting the present application.

For example, the number, size and arrangement of the fingerprint sensors are not specifically limited, and may be adjusted according to actual requirements. For example, the optical fingerprint module 130 may include a plurality of fingerprint sensors distributed in a square or circle.

At present, the technology of fingerprint identification under a screen mainly carries out fingerprint identification by the principle of reflected light imaging. As shown in fig. 5, after the light signals emitted from the pixels in the self-light-emitting display 120 irradiate the finger, a part of the light signals are transmitted and another part of the light signals are reflected. Since the index of refraction of the finger tissue is 1.43, the index of refraction of the optical signal at the ridges of the fingerprint is similar to the index of refraction of the display screen 120 (about 1.5), and the intensity of the transmitted optical signal at the ridges is higher and the intensity of the reflected optical signal is lower. Because the fingerprint valley is filled with air, the refractive index of the air is 1, and the difference between the refractive index of the air and the refractive index of the display screen 120 is large, the intensity of the transmitted light signal at the fingerprint valley is weak, and the intensity of the reflected light signal is high. The contrast in intensity of the light signal reflected back at the fingerprint ridges and at the fingerprint valleys is about 1: 40. Therefore, according to the intensity difference of the reflected light signals at the fingerprint ridge and the fingerprint valley, the fingerprint image of the finger can be obtained, and fingerprint identification is further carried out. As shown in fig. 6, the fingerprint image of a normal finger obtained by the principle of reflected light imaging has a good imaging effect, and can be used for fingerprint identification of a normal finger.

When a finger is wet, that is, the finger is a wet finger, the valley line is filled with water, and since the refractive index of water is about 1.33, and the refractive index of water is closer to the refractive index of the display screen 120 compared to the refractive index of air, the intensity of the light signal reflected back from the fingerprint valley when the finger is wet is seriously attenuated, and the contrast of the intensity of the light signal reflected back from the fingerprint ridge and the fingerprint valley is about 1: 2. At this time, since the contrast of the intensity of the reflected light signals at the fingerprint ridges and the fingerprint valleys is seriously degraded, the quality of the fingerprint image of the wet finger obtained according to the reflected light imaging principle is poor, as shown in fig. 7.

Therefore, in the case of wet fingers, fingerprint recognition cannot be performed by the principle of reflected light imaging. In addition, the 2D false fingerprint can be imaged by the principle of reflected light imaging, the imaging effect is similar to that of a real finger, and the risk of being cracked by the false fingerprint exists.

Therefore, the embodiment of the application provides a fingerprint detection device and an electronic device, and fingerprint identification is carried out by using a transmitted light imaging principle. The embodiment of the application can be applied to detection of various fingers, is particularly suitable for detection of wet fingers, can also be used for anti-counterfeiting of 2D fake fingers, and can improve fingerprint identification performance. The term "wet finger" refers to a wet finger or a wet finger.

Fingerprint recognition is performed by the principle of transmitted light imaging, as shown in fig. 8, light signals emitted from pixels in a self-light-emitting display 120 are transmitted into a finger and then transmitted out of the finger through the display. Because the refractive index of the finger tissue is similar to that of the display screen, the light in the finger tissue has higher intensity of the transmitted light signal and weaker intensity of the reflected light signal. The light in the finger tissue is transmitted from the valley and can enter the display screen only through two interfaces of skin and air and the display screen, so that the intensity of the light signal transmitted from the valley of the fingerprint is weaker, and the intensity of the reflected light signal is higher. The contrast of the intensity of the light signals transmitted at the ridges and the valleys of the fingerprint is about 50:1, and thus, a fingerprint image having a quality equivalent to that obtained by the reflected light imaging principle can be obtained according to the difference in the intensity of the light signals transmitted at the ridges and the valleys of the fingerprint to perform fingerprint recognition, as shown in fig. 9. Therefore, the fingerprint identification of the normal finger can be carried out by the transmitted light imaging principle.

When a finger is stained with water, the valley lines of the fingerprint are filled with water, the intensity of the light signals transmitted at the valley lines is slightly increased, but the water in the valley lines has a certain loss to the light and is still reflected on the interface between the water and the display screen, so that the intensity of the light signals transmitted at the ridges of the fingerprint is still greatly different from the intensity of the light signals transmitted at the valleys of the fingerprint, and the contrast ratio is about 20: 1. Therefore, the fingerprint identification of the wet finger by the transmitted light imaging principle can obtain the contrast which is 10 times of the light signal intensity obtained by the existing reflected light imaging principle, and the imaging quality can be better, as shown in fig. 10. Therefore, the fingerprint recognition performance for a wet finger can be improved by the principle of transmitted light imaging.

Fig. 11 is a partial schematic diagram of an electronic device 20 according to an embodiment of the application, and fig. 11 is a side view of the electronic device 20; fig. 12 illustrates a front view of an electronic device 20 according to an embodiment of the application. As shown in fig. 11 and 12, the electronic device 20 includes a display 200 and a fingerprint detection device 300, and the display 200 is located above the fingerprint detection device 300.

Specifically, the display 200 in FIG. 11 may represent a portion of the display 200, rather than the actual size and dimensions of the display 200; fig. 12 shows a front view of the display screen 200. The display screen 200 may correspond to the display screen 120 in the electronic device 10 described in fig. 1 and fig. 2, and is applicable to the description related to the display screen 120, and for brevity, will not be described again.

In addition, the electronic device 20 of the embodiment of the present application is described by taking as an example that the display screen 200 includes several light-emitting display pixels capable of self-emitting light, which can be used for displaying images. As shown in fig. 11 and 12, the display 200 includes a fingerprint detection area 210 for finger pressing, that is, when the user needs to unlock or otherwise identify the electronic device 20, the user only needs to press the finger on the fingerprint detection area 210 to input a fingerprint. The fingerprint detection area 210 may correspond to the fingerprint detection area 103 in the electronic device 10 described in fig. 1 to 4, and is suitable for the above description related to the fingerprint detection area 103, and for brevity, no further description is provided here.

In the embodiment of the present application, as shown in fig. 12, the display screen 200 includes a fingerprint detection area 210, the fingerprint detection area 210 includes a first area 211 and a second area 212, the second area 212 surrounds the first area 211, and the first area 211 and the second area 212 do not overlap.

It should be understood that the fingerprint detection device 300 is disposed below the display screen 200 of the terminal device 20 in the embodiment of the present application, and the fingerprint detection device 300 may be used to receive the optical signal returned by the finger. Specifically, the fingerprint detection apparatus 300 may include: an optical path guiding structure and an optical sensor disposed below the optical path guiding structure.

And an optical path guiding structure for guiding a first return light signal formed by a finger above the display screen to the optical sensor, wherein the first return light signal is a light signal in which the pixels in the first region 211 do not emit light, and the pixels in the second region 212 emit light which is transmitted into the finger, and then transmitted out of the finger and passes through the display screen.

Optionally, in an embodiment, the optical path guiding structure includes an optical lens disposed above the optical fingerprint sensor for converging the first return optical signal passing through the display screen to a sensing array of the optical fingerprint sensor.

Optionally, in an embodiment, the optical path guiding structure includes a microlens array having a plurality of microlenses and a light blocking layer having a plurality of micropores, and the microlens array is configured to focus the first return optical signal passing through the display screen to the corresponding micropores of the light blocking layer through the plurality of microlenses, respectively, and transmit the first return optical signal to the corresponding optical sensing units in the sensing array of the optical fingerprint sensor through the micropores.

An optical sensor for receiving the first return light signal passing through the optical path guiding structure, the first return light signal being for acquiring a fingerprint image of the finger.

That is, in the case where the pixels in the first region 211 in the fingerprint detection region 210 do not emit light and the pixels in the second region 212 emit light, the light irradiates the finger to generate a first return light signal, which is guided to the optical sensor via the optical path guide structure to acquire a fingerprint image of the finger.

Optionally, to prevent the reflected light signal generated after the light emitted by the pixels in the second region 212 irradiates the finger, the size of the first region 211 is not smaller than the diameter of the field of view of the fingerprint sensor. I.e. the size of the first area 211 may be larger than the diameter of the field of view of the fingerprint sensor or may be equal to the diameter of the field of view of the fingerprint sensor. It should be understood that the diameter of the field of view of the fingerprint sensor refers to the diameter of the corresponding area of the field of view of the fingerprint sensor on the display screen. For example, if the first area is a rectangle, the size of the dimension is the smallest value of the length or width of the rectangle.

In particular, the perpendicular projected area of the first region may coincide with the perpendicular projected area of the field of view of the fingerprint sensor, or the perpendicular projected area of the first region may cover the perpendicular projected area of the field of view of the fingerprint sensor.

Alternatively, considering that the light transmitted to the fingerprint sensor has a higher intensity after the light emitted by the pixels in the second area 212 irradiates the finger, so as to facilitate the acquisition of the fingerprint image of the finger, the size L of the first area 211 can be made to satisfy:

D≤L≤D+2×d×tanα

where D represents the diameter of the field of view of the optical sensor, D represents the distance of the pixel in the second region 212 from the upper surface of the display screen, and α represents the light emission angle of the pixel.

For example, the light emitting angle of the pixel in the display screen is between-60 ° and +60 °, as shown in fig. 13, the size L of the first region 211 may satisfy:

D≤L≤D+2×d×tan60°

alternatively, the first region 211 may be circular or square. When the shape of the first region 211 is a circle, the diameter of the circle satisfies the above condition; when the shape of the first region 211 is a square, the side length of the square may satisfy the above condition. It should be understood that the shape of the first region may also be any other regular shape, for example, a regular hexagon, a regular octagon. The embodiment of the present application is not limited to this.

Alternatively, the boundary of the second region 212 (light emitting region) may have a circular or square shape. The shape of the second region is preferably circular, but other shapes are possible to achieve the solution of the present application. As shown in fig. 14(a) to 14(d), the combination of the shapes of the first region 211 and the second region 212 in the fingerprint detection region 210 is illustrated.

Specifically, as shown in fig. 14(a), the combined shape of the first region and the second region is preferably concentric circles. Concentric circles are a more common combination of shapes.

14(b), the first area is square, the second area surrounds the first area, and the second area is circular. In this embodiment, the center of the first region coincides with the center of the second region.

14(c), the first area is circular, the second area surrounds the first area, and the second area is square. In this embodiment, the center of the first area coincides with the center of the second area.

14(d), the first area is square, the second area surrounds the first area, and the second area is square. In this embodiment, the center of the first region coincides with the center of the second region.

The shape of the fingerprint detection area 210 in the embodiment of the present application may be set according to practical applications, and may be set to any regular shape. The embodiment of the present application is not limited to this.

The shorter the wavelength of light irradiating the finger, the shallower the transmission depth of light in the finger, and the worse the effect of fingerprint imaging according to the transmitted light; the longer the wavelength of light irradiating the finger, the deeper the light is transmitted through the finger, and the better the effect of fingerprint imaging by the transmitted light is. Therefore, the pixels in the second region are preferably pixels that can emit red light or yellow light. The pixels in the second region may also be pixels in which the color of the emitted light is other displayable colors, for example, green, cyan, white, and the like. The embodiment of the present application is not limited to this.

Optionally, the fingerprint detection device may further include an optical filter, the optical filter is located above the optical fingerprint sensor, and the optical filter is configured to filter out other optical signals except the first return optical signal. For example, when the wavelength range of the first return light signal is preferably 600 to 660nm (red light band), the filter is used for filtering light with a wavelength not equal to 600 to 660 nm. In this case, in addition to the red light source, a good fingerprint imaging effect can be obtained by using light sources of other displayable colors.

The light intensity of the first return light signal received by the optical sensor may also be used to determine whether the finger is a real finger.

Specifically, as shown in fig. 11, assuming that the finger touching the fingerprint detection area 210 is a real finger, the light signal emitted from the illuminated second area returns after propagating through the finger, and the optical sensor can receive more transmitted light; however, in the case of a 2D false fingerprint, as shown in fig. 15, since the material of the 2D false fingerprint is different from the biological tissue, the optical signal cannot pass through the false fingerprint for fingerprint imaging, and therefore, the optical signal received by the optical sensor mainly depends on the self-reflection of the false fingerprint, and the optical sensor does not receive the optical signal or receives only a very small amount of optical signal under the action of the oblique receiving optical path or the vertical receiving optical path. That is, the intensity of the light signal received by the fingerprint sensor is greater than that of the 2D false fingerprint, so that the true and false fingerprint can be distinguished according to the characteristic. Specifically, if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, the finger is a real finger; and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, the finger is a fake finger.

A processor may be included in the electronic device 20 for determining whether the finger is a real finger based on the light intensity of the first return light signal received by the optical sensor. In particular, the processor may be configured to: if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, determining that the finger is a true finger; and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, determining that the finger is a fake finger.

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. The utility model provides a fingerprint detection's device, its characterized in that is applicable to the below of display screen in order to realize optical fingerprint detection under the screen, the display screen includes fingerprint detection area, fingerprint detection area includes first region and second area, the second area encircles the first region, fingerprint detection's device includes:

an optical path guiding structure for guiding a first return light signal formed by a finger above the display screen to an optical sensor, wherein the first return light signal is a light signal in which pixels in the first area do not emit light, and light emitted by pixels in the second area is transmitted into the finger, and then transmitted out of the finger and through the display screen;

an optical sensor disposed below the optical path guide structure for receiving the first return light signal passing through the optical path guide structure, the first return light signal being used to acquire a fingerprint image of the finger.

2. The apparatus of claim 1, wherein the first area is sized to be no smaller than a field of view diameter of the optical sensor.

3. The apparatus of claim 1, wherein the perpendicular projected area of the first region coincides with the perpendicular projected area of the field of view of the optical sensor, or wherein the perpendicular projected area of the first region covers the perpendicular projected area of the field of view of the optical sensor.

4. The apparatus of claim 1, wherein the dimension L of the first area satisfies:

D≤L≤D+2×d×tanα

5. The device of claim 1, wherein the first region is circular or square in shape and the second region is circular or square in shape at its boundary.

6. The device of claim 5, wherein the combined shape of the first region and the second region is concentric circles.

7. The device of claim 1, wherein the pixels in the second region emit light that is red or yellow.

8. The apparatus of claim 1, further comprising:

and the optical filter is positioned above the optical sensor and used for filtering other optical signals except the first return optical signal.

9. The apparatus of claim 8, wherein the first return light signal has a wavelength in the range of 600-660 nm, and the filter is configured to filter light having a wavelength not equal to 600-660 nm.

10. The apparatus of claim 1, wherein the optical path directing structure comprises an optical lens disposed above the optical sensor for focusing the first return optical signal passing through the display screen onto a sensing array of the optical sensor.

11. The apparatus of claim 1, wherein the optical path directing structure comprises a microlens array having a plurality of microlenses and a light-blocking layer having a plurality of micropores, the microlens array being configured to focus the first return optical signal passing through the display screen to the corresponding micropores of the light-blocking layer through the plurality of microlenses, respectively, and transmit the first return optical signal to the corresponding optical sensing units in the sensing array of the optical sensor through the micropores.

12. The apparatus of any one of claims 1 to 11, wherein the intensity of the first return light signal received by the optical sensor is used to determine whether the finger is a real finger.

13. The apparatus according to claim 12, wherein if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, the finger is a real finger;

and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, the finger is a fake finger.

14. An electronic device comprising a display screen and an apparatus for fingerprint detection according to any one of claims 1 to 12, said apparatus being arranged below said display screen to enable an off-screen optical fingerprint detection.

15. The electronic device of claim 14, further comprising: and the processor is used for determining whether the finger is a real finger or not according to the light intensity of the first return light signal received by the optical sensor.

16. The electronic device of claim 15, wherein the processor is specifically configured to:

if the light intensity of the first return light signal received by the optical sensor is greater than or equal to a preset value, determining that the finger is a true finger;

and if the light intensity of the first return light signal received by the optical sensor is smaller than the preset value, determining that the finger is a fake finger.