WO2020186415A1

WO2020186415A1 - Device and method for fingerprint recognition, and electronic apparatus

Info

Publication number: WO2020186415A1
Application number: PCT/CN2019/078458
Authority: WO
Inventors: 黄力; 吴东承
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2019-03-18
Filing date: 2019-03-18
Publication date: 2020-09-24
Also published as: CN110100250A; CN110100250B

Abstract

Provided are a device and method for fingerprint recognition, and an electronic apparatus capable of reducing the impact of a film attached to a display screen on in-screen fingerprint recognition performance. The device comprises: an optical fingerprint sensor used to perform imaging of an optical signal reflected by a finger above a display screen so as to obtain a fingerprint image of the finger; and a processing unit used to acquire the thickness of a film attached to the display screen, and to determine a fingerprint algorithm according to the thickness of the film, the fingerprint algorithm being used to perform fingerprint recognition on the basis of the fingerprint image.

Description

Fingerprint identification device, method and electronic equipment

Technical field

The embodiments of the present application relate to the field of biometric identification, and more specifically, to a fingerprint identification device, method, and electronic device.

Background technique

The fingerprint recognition technology under the optical screen uses the optical fingerprint sensor to collect the light emitted by the light source and reflect the reflected light on the finger above the display, and obtain the fingerprint image of the finger according to the reflected light, thereby performing fingerprint recognition based on the fingerprint image . People usually like to stick a layer of film on the surface of the display screen of the device, and the film has a certain thickness, so it will affect the performance of fingerprint recognition under the screen.

Summary of the invention

The embodiments of the present application provide a fingerprint identification method, device and electronic equipment, which can reduce the influence of the film on the display screen on the fingerprint identification performance under the screen.

In a first aspect, a fingerprint identification device is provided, which is applied to an electronic device with a display screen, and the device includes:

An optical fingerprint sensor for imaging the light signal reflected by the finger above the display screen to obtain a fingerprint image of the finger;

The processing unit is configured to: obtain the thickness of the sticker on the display screen; determine a fingerprint algorithm according to the thickness of the sticker, and the fingerprint algorithm is used for fingerprint recognition based on the fingerprint image.

In a possible implementation, the optical fingerprint sensor is also used to: collect a first image and a second image of a light spot with a specific shape emitted by the excitation light source for fingerprint recognition, and the first image is the image of the light spot. An image formed by direct light, and the second image is an image formed by light reflected by the upper surface of the film of the light spot;

The processing unit is specifically configured to determine the thickness of the sticker film according to the first image and the second image.

In a possible implementation manner, the processing unit is specifically configured to determine the thickness of the sticker film according to the difference between the radial length of the first image and the second image.

In a possible implementation manner, the larger the difference between the radial length of the first image and the second image, the smaller the thickness of the sticker.

In a possible implementation, the excitation light source is a light-emitting layer of the display screen, and the light spot is located in a fingerprint collection area in the display screen.

In a possible implementation, the device further includes a lens, which is located between the display screen and the optical fingerprint sensor, and is used to combine the direct light from the light spot with the upper surface of the film. The reflected light is imaged to the optical fingerprint sensor.

In a possible implementation manner, the specific shape is a circular, elliptical, triangular, rectangular, or polygonal ring.

In a possible implementation, the light spot is a monochromatic light spot or a composite color light spot.

In a possible implementation, the light spot is a bright light spot on a dark background, or a dark light spot on a bright background.

In a possible implementation manner, the processing unit is specifically configured to: determine the range to which the thickness of the sticker belongs; among a plurality of fingerprint algorithms, select the fingerprint algorithm corresponding to the range.

In a second aspect, a fingerprint identification method is provided, including: obtaining the thickness of a sticker on a display screen; and determining a fingerprint algorithm according to the thickness of the sticker, and the fingerprint algorithm is used for fingerprint recognition.

In a possible implementation, the obtaining the thickness of the film on the display screen includes: collecting a first image and a second image with a specific shape of a light spot emitted by an excitation light source for fingerprint recognition, and the first image is The image formed by the direct light of the light spot, and the second image is an image formed by the light reflected by the upper surface of the film of the light spot; according to the first image and the second image, the The thickness of the film.

In a possible implementation manner, the determining the thickness of the sticker film according to the first image and the second image includes: according to the radial length of the first image and the second image The difference determines the thickness of the film.

In a possible implementation, the greater the difference between the radial length of the first image and the second image, the smaller the thickness of the sticker.

In a possible implementation manner, the determining the fingerprint algorithm according to the thickness of the sticker includes: determining the range to which the thickness of the sticker belongs; among a plurality of fingerprint algorithms, selecting the fingerprint corresponding to the range algorithm.

In a third aspect, a terminal device is provided, including:

Display screen

Optical fingerprint sensor; and,

The fingerprint recognition device in the second aspect or any possible implementation of the second aspect.

Based on the above technical solution, according to the thickness of the film on the display screen, a fingerprint algorithm for processing the collected fingerprint images is selected, so that fingerprint recognition can adapt to the thickness of the film, thereby reducing the impact of the film on fingerprint recognition performance.

Description of the drawings

Fig. 1 is a schematic diagram of the structure of an electronic device to which this application can be applied.

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

FIG. 3 is a schematic block diagram of a fingerprint recognition device 300 according to an embodiment of the present application.

Fig. 4 is a schematic diagram of a method for detecting the thickness of a film according to an embodiment of the present application.

Fig. 5(a) is a schematic diagram of light spots on the light-emitting layer of the display screen.

Figure 5(b) is a schematic diagram of the spot image corresponding to the film.

Figure 5(c) is a schematic diagram of a light spot image corresponding to a thick film.

FIG. 6 is a schematic diagram of data of light spot images corresponding to thin films and thick films.

Fig. 7 is a schematic diagram of light spots of different shapes.

Fig. 8 is a schematic diagram of light spots under different backgrounds.

FIG. 9 is a schematic flowchart of a fingerprint identification method according to an embodiment of the present application.

detailed description

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

It should be understood that the embodiments of this application can be applied to optical fingerprint systems, including but not limited to optical fingerprint identification systems and medical diagnostic products based on optical fingerprint imaging. The embodiments of this application only take optical fingerprint systems as an example for description, but should not The embodiments of the application constitute any limitation, and the embodiments of the present application are also applicable to other systems using optical imaging technology.

As a common application scenario, the optical fingerprint system provided in the embodiments of this application can be applied to smart phones, tablet computers, and other mobile terminals with display screens or other terminal devices; more specifically, in the above-mentioned terminal devices, the optical fingerprint The module may be specifically an optical fingerprint module, which may be arranged in a partial area or the entire area below the display screen to form an under-display or under-screen optical fingerprint system. Alternatively, the optical fingerprint module can also be partially or fully integrated into the display screen of the terminal device to form an in-display or in-screen optical fingerprint system.

Figures 1 and 2 show schematic diagrams of electronic devices to which the embodiments of the present application can be applied. 1 is a schematic view of the orientation of the electronic device 10, and FIG. 2 is a schematic partial cross-sectional view of the electronic device 10 shown in FIG.

The terminal device 10 includes a display screen 120 and an optical fingerprint module 130. Wherein, the optical fingerprint module 130 is arranged in a partial area below the display screen 120. The optical fingerprint module 130 includes an optical fingerprint sensor, and the optical fingerprint sensor includes a sensing array 133 having a plurality of optical sensing units 131. The area where the sensing array 133 is located or its sensing area is the fingerprint detection area 121 of the optical fingerprint module 130 (also referred to as fingerprint collection area, fingerprint recognition area, etc.). As shown in FIG. 1, the fingerprint detection area 121 is located in the display area of the display screen 120. In an alternative embodiment, the optical fingerprint module 130 may also be arranged in other positions, such as the side of the display screen 120 or the non-transparent area of the edge of the terminal device 10, and the optical fingerprint module 130 The optical signal of at least part of the display area of the display screen 120 is guided to the optical fingerprint module 130 so that the fingerprint detection area 121 is actually located in the display area of the display screen 120.

It should be understood that the area of the fingerprint detection area 121 may be different from the area of the sensing array 133 of the optical fingerprint module 130, for example, through an optical path design such as lens imaging, a reflective folding optical path design, or other optical paths such as light convergence or reflection. The design can make the area of the fingerprint detection area 121 of the optical fingerprint module 130 larger than the area of the sensing array 133 of the optical fingerprint module 130. In other alternative implementations, if for example, light collimation is used for light path guidance, the fingerprint detection area 121 of the optical fingerprint module 130 can also be designed to be substantially the same as the area of the sensing array of the optical fingerprint module 130.

Therefore, when the user needs to unlock the terminal device or perform other fingerprint verification, he only needs to press his finger on the fingerprint detection area 121 of the display screen 120 to realize fingerprint input. Since fingerprint detection can be implemented in the screen, the terminal device 10 adopting the above structure does not need to reserve a space on the front side for the fingerprint button (such as the Home button), so that a full screen solution can be adopted, that is, the display area of the display screen 120 It can be basically extended to the front of the entire terminal device 10.

As an optional implementation manner, as shown in FIG. 1, the optical fingerprint module 130 includes a light detecting part 134 and an optical component 132. The light detection part 134 includes the sensing array 133, a reading circuit electrically connected to the sensing array 133, and other auxiliary circuits, which can be fabricated on a chip (Die) by a semiconductor process, such as an optical imaging chip or Optical fingerprint sensor. The sensing array 133 is specifically a photodetector (Photodetector) array, which includes a plurality of photodetectors distributed in an array, and the photodetectors can be used as the aforementioned optical sensing unit. The optical component 132 may be disposed above the sensing array 133 of the light detecting part 134, and it may specifically include a filter layer (Filter), a light guide layer or a light path guiding structure, and other optical elements. The filter layer It can be used to filter out ambient light penetrating the finger, and the light guide layer or light path guiding structure is mainly used to guide the reflected light reflected from the surface of the finger to the sensor array 133 for optical detection.

In terms of specific implementation, the optical assembly 132 and the light detecting part 134 may be packaged in the same optical fingerprint component. For example, the optical component 132 and the optical detection part 134 can be packaged in the same optical fingerprint chip, or the optical component 132 can be arranged outside the chip where the optical detection part 134 is located, for example, the optical component 132 is attached above the chip, or some components of the optical assembly 132 are integrated into the chip.

Wherein, the light guide layer or light path guiding structure of the optical component 132 has multiple implementation schemes. For example, the light guide layer may specifically be a collimator layer made on a semiconductor silicon wafer, which has multiple A collimating unit or a micro-hole array. The collimating unit can be specifically a small hole. Among the reflected light reflected from the finger, the light that is perpendicularly incident on the collimating unit can pass through and be passed by the optical sensing unit below it. The light with an excessively large incident angle is attenuated by multiple reflections inside the collimating unit. Therefore, each optical sensing unit can basically only receive the reflected light reflected by the fingerprint pattern directly above it. The sensing array 133 can detect the fingerprint image of the finger.

In another embodiment, the light guide layer or the light path guide 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, which The sensing array 133 of the light detecting part 134 is used to converge the reflected light reflected from the finger to the sensing array 133 of the light detection part 134 below, so that the sensing array 133 can perform imaging based on the reflected light, thereby obtaining a fingerprint image of the finger. Optionally, the optical lens layer may further have a pinhole formed in the optical path of the lens unit, and the pinhole may cooperate with the optical lens layer to expand the field of view of the optical fingerprint module 130 to improve The fingerprint imaging effect of the optical fingerprint module 130 is described.

In other embodiments, the light guide layer or the light path guide 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 can be grown by semiconductors. A process or other processes are formed above the sensing array 133 of the light detecting part 134, and each microlens may correspond to one of the sensing units of the sensing array 133, respectively. In addition, other optical film layers may be formed between the microlens layer and the sensing unit, such as a dielectric layer or a passivation layer. More specifically, between the microlens layer and the sensing unit, a light blocking layer (or called a light shielding layer) with microholes may also be included, wherein the microholes are formed between the corresponding microlens and the sensing unit. In between, the light blocking layer can block the optical interference between the adjacent microlens and the sensing unit, and make the light corresponding to the sensing unit converge into the microhole through the microlens and pass through the microhole. It is transmitted to the sensing unit for optical fingerprint imaging.

It should be understood that the above-mentioned several implementation schemes of the light guide layer or light path guide structure can be used alone or in combination. For example, a micro lens layer may be further provided 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 micro lens layer, its specific laminated structure or optical path may need to be adjusted according to actual needs.

As an optional embodiment, the display screen 120 may be a display screen with a self-luminous display unit, such as an organic light-emitting diode (Organic Light-Emitting Diode, OLED) display or a micro-LED (Micro-LED) display Screen. Taking an OLED display screen as an example, the optical fingerprint module 130 may use the display unit (ie, an OLED light source) of the OLED display screen 120 located in the fingerprint detection area 121 as an excitation light source for optical fingerprint detection. When the finger 140 is pressed on the fingerprint detection area 121, the display screen 120 emits a beam of light 111 to the target finger 140 above the fingerprint detection area 121. The light 111 is reflected on the surface of the finger 140 to form reflected light or pass through all the fingers. The finger 140 scatters to form scattered light. In related patent applications, for ease of description, the above-mentioned reflected light and scattered light are collectively referred to as reflected light. Because the ridge 141 and valley 142 of the fingerprint have different light reflection capabilities, the reflected light 151 from the fingerprint ridge and the reflected light 152 from the fingerprint valley have different light intensities, and the reflected light passes through the optical component 132. After that, it is received by the sensor array 133 in the optical fingerprint module 130 and converted into a corresponding electrical signal, that is, a fingerprint detection signal; based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification can be further performed, thereby The terminal device 10 realizes the optical fingerprint recognition function.

In other embodiments, the optical fingerprint module 130 may also use a built-in light source or an external light source to provide an optical signal for fingerprint detection. In this case, the optical fingerprint module 130 may be suitable for non-self-luminous display screens, such as liquid crystal display screens or other passively-luminous display screens. Taking a liquid crystal display with a backlight module and a liquid crystal panel as an example, in order to support the under-screen fingerprint detection of the liquid crystal display, the optical fingerprint system of the terminal device 10 may also include an excitation light source for optical fingerprint detection. The excitation light source may specifically be an infrared light source or a light source of invisible light of a specific wavelength, which may be arranged under the backlight module of the liquid crystal display or arranged in the edge area under the protective cover of the terminal device 10, and the The optical fingerprint module 130 may be arranged under the edge area of the liquid crystal panel or the protective cover and guided by the light path so that the fingerprint detection light can reach the optical fingerprint module 130; or, the optical fingerprint module 130 may also be arranged at all Below the backlight module, and the backlight module is designed to allow the fingerprint detection light to pass through the liquid crystal panel and the backlight module and reach the optical Fingerprint module 130. When the optical fingerprint module 130 uses a built-in light source or an external light source to provide an optical signal for fingerprint detection, the detection principle is the same as that described above.

It should be understood that, in specific implementation, the terminal device 10 further includes a transparent protective cover, and the cover may be a glass cover or a sapphire cover, which is located above the display screen 120 and covers the terminal. The front of the device 10. Therefore, in the embodiments of the present application, the so-called finger pressing on the display screen 120 actually refers to pressing on the cover plate above the display screen 120 or covering the surface of the protective layer of the cover plate.

On the other hand, in some embodiments, the optical fingerprint module 130 may include only one optical fingerprint sensor. At this time, the fingerprint detection area 121 of the optical fingerprint module 130 has a small area and a fixed position, so the user is performing During fingerprint input, it is necessary to press the finger to a specific position of the fingerprint detection area 121, otherwise the optical fingerprint module 130 may not be able to collect fingerprint images, resulting in poor user experience. In other alternative embodiments, the optical fingerprint module 130 may specifically include multiple optical fingerprint sensors. The multiple optical fingerprint sensors may be arranged side by side under the display screen 120 in a splicing manner, and the sensing areas of the multiple optical fingerprint sensors collectively constitute the fingerprint detection area 121 of the optical fingerprint module 130. In other words, the fingerprint detection area 121 of the optical fingerprint module 130 may include multiple sub-areas, and each sub-area corresponds to the sensing area of one of the optical fingerprint sensors, so that the fingerprint detection area of the optical fingerprint module 130 121 can be extended to the main area of the lower half of the display screen, that is, to the area where the finger is habitually pressed, so as to realize the blind fingerprint input operation. Alternatively, when the number of optical fingerprint sensors is sufficient, the fingerprint detection area 130 can also be extended to half of the display area or even the entire display area, thereby realizing half-screen or full-screen fingerprint detection.

At present, there are many types of mobile phone film on the market, and the thickness of the film varies greatly. For example, the thickness of the ordinary film is smaller, and the thickness of the tempered film is larger. The fingerprint algorithm used for fingerprint recognition is usually optimized based on a specific film thickness, and only a film of that specific thickness can achieve better fingerprint recognition performance. If the user sticks a film of other thickness on his mobile phone, it may affect the performance of fingerprint recognition.

In view of this, the embodiment of the present application proposes a fingerprint recognition solution, which detects the thickness of the film on the upper surface of the display screen, and selects an appropriate fingerprint algorithm based on the obtained film thickness, so that fingerprint recognition has a better effect on different film thicknesses. The adaptability improves the performance of fingerprint recognition.

Fig. 3 is a schematic block diagram of a fingerprint recognition device according to an embodiment of the present application. As shown in FIG. 3, the device 300 is applied to an electronic device with a display screen. The fingerprint identification device 300 may be an electronic device, such as the electronic device 10 described in FIGS. 1 and 2; it may also be an optical fingerprint module in the terminal device, and the optical fingerprint module may be, for example, FIG. And the optical fingerprint module 130 described in FIG. 2.

As shown in FIG. 3, the fingerprint recognition device 300 includes an optical fingerprint sensor 310 and a processing unit 320. among them:

The optical fingerprint sensor 310 is used for imaging the light signal reflected by the finger above the display screen to obtain a fingerprint image of the finger.

The processing unit 320 is configured to: obtain the thickness of the sticker on the display screen; and determine the fingerprint algorithm according to the thickness of the sticker.

Among them, the fingerprint algorithm is used for fingerprint recognition based on the fingerprint image.

In this embodiment, the processing unit 320 obtains the thickness of the sticker on the display screen, and selects an appropriate fingerprint algorithm according to the thickness of the sticker, so that the fingerprint algorithm is used to process the fingerprint image collected by the optical fingerprint sensor 310, so that the fingerprint Recognition has better adaptability to different film thicknesses and improves the performance of fingerprint recognition.

The fingerprint algorithm for different film thicknesses may be different.

For example, when the thickness of the film is different, the dots per inch (DPI) of the fingerprint image collected by the optical fingerprint sensor 310 may be different, so the fingerprint algorithm used when performing image processing on the fingerprint image can be adjusted adaptively.

Optionally, the processing unit 320 is specifically configured to: determine the film thickness range to which the thickness of the sticker film belongs; and select the fingerprint algorithm corresponding to the film thickness range among the candidate fingerprint algorithms.

For example, multiple film thickness ranges can be preset, and multiple candidate fingerprint algorithms corresponding to the multiple film thickness ranges. The data obtained through repeated experiments can be used to determine the best fingerprint algorithm for different film thicknesses.

Take Table 1 as an example for description. It is assumed that 4 fingerprint algorithms are preset, corresponding to 4 film thickness ranges. If the thickness of the detected film is 0-0.15 mm, select fingerprint algorithm 1 to process the collected fingerprint image. If the thickness of the detected film is 0.15-0.2 mm, select fingerprint algorithm 2 to process the collected fingerprint image. If the thickness of the detected film is 0.2-0.35 mm, fingerprint algorithm 3 is selected to process the collected fingerprint image. If the thickness of the detected film is 0.35-0.45 mm, select fingerprint algorithm 4 to process the collected fingerprint image.

Table I

膜厚范围Film thickness range	指纹算法Fingerprint algorithm
0mm-0.15mm0mm-0.15mm	指纹算法1Fingerprint algorithm 1
0.15mm-0.2mm0.15mm-0.2mm	指纹算法2Fingerprint Algorithm 2
0.2mm-0.35mm0.2mm-0.35mm	指纹算法3Fingerprint Algorithm 3
0.35mm-0.45mm0.35mm-0.45mm	指纹算法4Fingerprint Algorithm 4

The fingerprint algorithm may be, for example, an algorithm used in processes such as preprocessing of fingerprint images, image enhancement, image feature extraction, and feature matching.

For example, different fingerprint algorithms use different parameters for filtering fingerprint images.

For another example, the parameters used to convolve the fingerprint image in different fingerprint algorithms are different.

For another example, different fingerprint algorithms use different similarity thresholds when matching fingerprint images. When the similarity between the collected fingerprint image and the fingerprint image in the fingerprint library reaches the similarity threshold, it can be confirmed that the fingerprint recognition is successful.

Hereinafter, the method for detecting the thickness of the film in the embodiment of the present application will be described in detail with reference to FIGS. 4 to 8.

Optionally, the optical fingerprint sensor 310 is also used to collect the first image and the second image of the light spot with a specific shape emitted by the excitation light source for fingerprint recognition.

Wherein, the first image is an image formed by direct light from the light spot, and the second image is an image formed by light reflected by the upper surface of the film of the light spot.

At this time, the processing unit 320 is specifically configured to determine the thickness of the sticker film according to the first image and the second image.

The excitation light source used for fingerprint recognition is, for example, the light-emitting layer of the display screen, for example, the light-emitting layer of an OLED or other self-luminous display screens. Alternatively, the excitation light source may also be an additional light source provided outside the display screen.

The fingerprint detection area of the optical fingerprint sensor 310 is located in the display screen. Optionally, the light spot is located in a fingerprint detection area in the display screen.

The thickness of the film can be detected when the finger is pressed in the fingerprint detection area for fingerprint recognition. At this time, the touch of the finger can trigger the process of detecting the film thickness.

Of course, it is also possible to detect the thickness of the film based on the interface reflection on the upper surface of the film when there is no finger pressing.

In the embodiment of the present application, the light emitted by the excitation light source for fingerprint recognition forms a light spot with a specific shape. The optical fingerprint sensor 310 collects a first image formed by the direct light of the light spot, and a second image formed by the light reflected by the light spot on the upper surface of the film.

The first image is obtained based on the direct rays of the light spot, so the real image of the light spot is obtained. The second image is obtained based on the reflected light formed by the light spot on the upper surface of the film, so the virtual image of the light spot is obtained. The real image and virtual image of the light spot are symmetrical with respect to the upper surface of the film, and the virtual image of the light spot is located above the film, and the virtual image of the light spot is located below the film. Since the real image and the virtual image of the light spot are at different distances from the optical fingerprint sensor 310, the size of the first image and the second image collected by the optical fingerprint sensor 310 are different. Based on the difference between the first image and the second image, the distance between the real image and the virtual image of the light spot can be determined, thereby determining the thickness of the sticker.

For example, the thickness of the sticker can be determined based on the difference between the radial length of the first image and the second image.

Wherein, the greater the difference between the radial length of the first image and the second image, the greater the thickness of the film; the smaller the difference between the radial length of the first image and the second image, the smaller the film’s The smaller the thickness.

This is because the first image collected by the optical fingerprint sensor 310 is a real image of the light spot, and the second image collected by the optical fingerprint sensor 310 is a virtual image of the light spot. When the spot position is unchanged, the size of the image is not affected by the thickness of the film because the distance between the spot and the optical fingerprint sensor 310 is constant. However, the size of the virtual image of the light spot will be affected by the thickness of the film. The greater the thickness of the film, the farther the virtual image is from the real image and the farther away from the optical fingerprint sensor 310. Therefore, the smaller the virtual image of the light spot collected by the optical fingerprint sensor 310, the greater the radial length difference between the real image and the virtual image; the greater the film thickness Smaller, the closer the virtual image is to the real image, the closer it is to the optical fingerprint sensor 310. Therefore, the larger the virtual image collected by the optical fingerprint sensor 310, the smaller the radial length difference between the real image and the virtual image.

Optionally, the fingerprint identification device 300 further includes a lens 330, which is located between the display screen and the optical fingerprint sensor 310, and is used to image the direct light from the spot and the light reflected by the upper surface of the film to Optical fingerprint sensor 310.

The lens 330 guides the direct light of the spot and the light reflected by the upper surface of the film to the sensing array of the optical fingerprint sensor 310. The optical fingerprint sensor 310 collects the direct light from the light spot and the light reflected by the upper surface of the film. The reflected light obtains the real and virtual images of the spot.

The principle of detecting the thickness of the film in the embodiment of the present application will be described in detail below with reference to FIG. 4. FIG. 4 shows a display screen 410, a lens 420 and an optical fingerprint sensor 430 arranged in sequence below the display screen 410. Wherein, the display screen 410 includes an OLED light-emitting layer 411, a glass cover plate 412 and a sticker 413. The distance setting between the display screen 410, the lens 420, and the optical fingerprint sensor 430 satisfies the imaging condition of the lens 420. When the finger is performing fingerprint recognition, the finger is in contact with the upper surface of the sticker 413.

As shown in FIG. 4, the OLED light-emitting layer 411 has an OLED virtual image layer 414 symmetrical about the upper surface of the film. The light emitted from the OLED light-emitting layer 411 forms a light spot 440 with a specific shape. The light of the light spot 440 is reflected on the upper surface of the film 413, that is, on the surface where the finger contacts the display screen, to form reflected light. The reflected light forms a virtual image of the spot 440 on the OLED virtual image layer 414.

Since the light spot 440 and its virtual image are at different distances from the lens 420, the size of the real image and the virtual image of the light spot 440 collected by the optical fingerprint sensor 430 through the lens 420 are different. Based on the difference between the real image and the virtual image of the light spot 440, it can be determined The thickness of the film 413.

Assume that the light spot 440 on the OLED light-emitting layer 411 is a ring-shaped light spot as shown in FIG. 5(a). Part of the light in the ring spot is directly transmitted to the optical fingerprint sensor 430. After the optical fingerprint sensor 430 collects this part of the light, the real image of the spot 440 can be obtained, that is, the outer ring image in FIGS. 5(b) and 5(c). Hereinafter referred to as the outer ring, its radius is R ₀ . Another part of the light in the ring light spot illuminates the finger above the display screen 410, and the optical fingerprint sensor 430 collects the reflected light generated by the finger to obtain a virtual image of the ring light spot formed by the reflected light, as shown in Figure 5(b) and Figure 5( c) The inner ring image in, hereinafter referred to as the inner ring.

Based on the principle of lens imaging, the farther away from the lens, the smaller the image formed. Therefore, the thicker the film 413, the farther the virtual image of the ring light spot symmetrical with respect to the upper surface of the film 413 is from the lens 420, the smaller the virtual image of the ring light spot collected by the optical fingerprint sensor 430. On the contrary, the thinner the film 413 is, the closer the virtual image of the ring light spot symmetrical to the upper surface of the film 413 is from the lens 420, the larger the virtual image of the ring light spot collected by the optical fingerprint sensor.

The radius of the inner ring collected by the optical fingerprint sensor 430 when a thin film is used as shown in FIG. 5(b) is R ₁ , and the radius of the inner ring collected by the optical fingerprint sensor 430 when a thick film is used as shown in FIG. 5(b) The radius is R ₂ . It can be seen that R ₁ > R ₂ .

In FIG. 4, the film thickness detection can be triggered by pressing the display screen 410 with a finger. For example, the user triggers the film thickness detection when performing fingerprint recognition. At this time, the film thickness detection can be realized based on the reflected light of the finger, that is, the light reflected by the finger. It is imaged to the optical fingerprint sensor 430 to obtain a virtual image of the light spot 440. At this time, since the pressing position of the finger is uncertain, the thickness of the sticker 413 can be determined based on the radius difference between the real image and the virtual image of the annular light spot collected by the optical fingerprint sensor 430. The greater the difference in radius, the greater the thickness of the film 413. For example, in Fig. 5(b), the radius difference is R _0- R ₁ , and in Fig. 5 (c), the radius difference is R _0- R ₂ . Since R1>R2, correspondingly, R ₀ -R ₁ <R ₀ -R ₂ , the thickness of the sticker 413 corresponding to FIG. 5(b) is smaller than the thickness of the sticker 413 corresponding to FIG. 5(c).

However, when there is no finger above the display screen 410, the film thickness detection can still be implemented based on the method described in the embodiment of the present application. At this time, it can be realized based on the interface reflection of the upper surface of the sticker 413, that is, the light reflected by the upper surface of the sticker 412 is imaged to the optical fingerprint sensor 430 to obtain a virtual image of the light spot 440. At this time, the difference in film thickness can be judged based on the size of R ₀ -R ₁ and R ₀ -R ₂ ; or, when the position of the spot 400 on the OLED light-emitting layer 411 is fixed, it can also be judged directly based on the size of R ₁ and R ₂ Difference in film thickness. For example, according to R ₁ >R ₂ , it can be determined that the thickness of the film 413 corresponding to FIG. 5(b) is smaller than the thickness of the film 413 corresponding to FIG. 5(c).

Fig. 6 shows data extracted along any diameter direction in Fig. 5(b) and Fig. 5(c). Wherein, the horizontal axis is the position coordinate in the diameter direction, and the vertical axis is the data value collected by the optical fingerprint sensor 430, and the data value may represent light intensity or brightness. Fig. 6 shows the respective radial light intensity curves corresponding to the thin film and the thick film. Among them, the first peak and last peak of the curve represent the outer ring in Fig. 5(b) and Fig. 5(c), and the two peaks in the middle of the curve represent the inner ring in Fig. 5(b) and Fig. 5(c). ring. It can be seen that the diameter of the inner ring corresponding to the thin film is larger than the diameter of the inner ring corresponding to the thick film.

The optical fingerprint sensor 430 obtains a virtual image and a real image of the light spot 440 on the OLED light-emitting layer by imaging the light spot 440 with a special shape, so that the film thickness information can be obtained based on the difference between the virtual image and the real image of the light spot 440.

Among them, for example, as shown in FIG. 7, the light spot of a specific shape in the embodiment of the present application can be a ring, such as a circle, an ellipse, a triangle, a rectangle, a polygon, or a ring of any shape; it can also be a light spot of other shapes, such as The spot is two vertical bars "||" and so on. The embodiments of this application do not limit this. Preferably, the shape of the light spot is selected so that the real image and the virtual image of the light spot collected by the optical fingerprint sensor do not overlap.

In addition, the embodiment of the present application does not limit the color of the light spot, for example, it may be a monochromatic light spot or a light spot of composite color.

In addition, as shown in FIG. 8, the embodiment of the present application does not limit the background color of the light spot. For example, it may be a bright light spot under a dark background or a dark light spot under a bright background.

In the embodiment of the present application, the fingerprint recognition device 300 can detect the thickness of the film by imaging the light spot formed by the excitation light source, or obtain the thickness of the film by other means, such as inputting the thickness of the film by the user, so that the device 300 is based on the user The input film thickness selects the matching fingerprint algorithm.

The embodiment of the application also provides a method for fingerprint identification. As shown in Figure 9, the method may include all or part of the following steps.

Step 910: Obtain the thickness of the film on the display screen.

Step 920: Determine a fingerprint algorithm according to the thickness of the sticker, and the fingerprint algorithm is used for fingerprint identification.

The optical fingerprint sensor collects the light reflected by the finger above the display screen to obtain the fingerprint image of the finger. At the same time, the thickness of the film above the display screen is acquired, and an appropriate fingerprint algorithm is selected based on the thickness of the film, so that the fingerprint algorithm is used to process the fingerprint image, which can improve the adaptability of fingerprint recognition to the thickness of the film.

For example, it is possible to determine the film thickness range that the thickness of the film on the upper surface of the display screen belongs to, and select the fingerprint algorithm corresponding to the film thickness range among the candidate fingerprint algorithms.

Optionally, in 910, the obtaining the thickness of the film on the display screen includes: collecting a first image and a second image with a light spot with a specific shape emitted by an excitation light source for fingerprint recognition, where the first image is The image formed by the direct light of the light spot, the second image is an image formed by the light reflected by the upper surface of the film of the light spot; the film is determined according to the first image and the second image thickness of.

The first image is obtained based on the direct rays of the light spot, so the real image of the light spot is obtained. The second image is obtained based on the reflected light formed by the light spot on the upper surface of the film, so the virtual image of the light spot is obtained. The real image and virtual image of the light spot are symmetrical with respect to the upper surface of the film, and the virtual image of the light spot is located above the film, and the virtual image of the light spot is located below the film. Since the real image and the virtual image of the light spot are at different distances from the optical fingerprint sensor, the size of the first image and the second image collected by the optical fingerprint sensor are different. Based on the difference between the first image and the second image, the distance between the real image and the virtual image of the light spot can be determined, thereby determining the thickness of the sticker.

Wherein, the greater the difference between the radial length of the first image and the second image, the greater the thickness of the sticker. The smaller the difference between the radial length of the first image and the second image, the smaller the thickness of the sticker.

The greater the thickness of the film, the farther the virtual image is from the real image and the farther from the optical fingerprint sensor. Therefore, the smaller the virtual image of the light spot collected by the optical fingerprint sensor, the greater the radial length difference between the real image and the virtual image; the smaller the film thickness, The closer the virtual image is to the real image, the closer it is to the optical fingerprint sensor. Therefore, the larger the virtual image collected by the optical fingerprint sensor, the smaller the radial length difference between the real image and the virtual image.

In the fingerprint identification method 900, the method of detecting the thickness of the film and the process of selecting the fingerprint algorithm can refer to the foregoing specific descriptions of FIGS. 3 to 8. For the sake of brevity, details are not repeated here. The features on the device side also apply to method testing.

The embodiments of the present application also provide an electronic device, which includes a display screen, an optical fingerprint sensor, and the fingerprint recognition device in the various embodiments of the present application.

Among them, the display screen can be a common display screen or a flexible display screen.

As an example and not a limitation, the electronic devices in the embodiments of the present application may be portable or mobile computing devices such as terminal devices, mobile phones, tablet computers, notebook computers, desktop computers, game devices, in-vehicle electronic devices, or wearable smart devices, and Electronic databases, automobiles, bank automated teller machines (Automated Teller Machine, ATM) and other electronic equipment. The wearable smart device includes full-featured, large-sized, complete or partial functions that can be achieved without relying on smart phones, such as smart watches or smart glasses, etc., and only focus on a certain type of application function, and need to cooperate with other devices such as smart phones Use, such as various types of smart bracelets, smart jewelry and other equipment for physical sign monitoring.

It should be noted that, under the premise of no conflict, the various embodiments described in this application and/or the technical features in each embodiment can be combined with each other arbitrarily, and the technical solutions obtained after the combination should also fall within the protection scope of this application. .

It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than limiting the scope of the embodiments of the present application. Those skilled in the art can base on the above-mentioned embodiments. Various improvements and modifications are made, and these improvements or modifications fall within the scope of protection of the present application.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application. Should be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

A fingerprint identification device, characterized in that it is applied to an electronic device with a display screen, and the device includes:

An optical fingerprint sensor for imaging the light signal reflected by the finger above the display screen to obtain a fingerprint image of the finger;

Processing unit for:

Obtaining the thickness of the film on the display screen;

A fingerprint algorithm is determined according to the thickness of the sticker, and the fingerprint algorithm is used for fingerprint recognition based on the fingerprint image.
The device according to claim 1, wherein the optical fingerprint sensor is further used for:

Collect a first image and a second image of a light spot with a specific shape emitted by an excitation light source for fingerprint recognition, where the first image is an image formed by the direct light of the light spot, and the second image is the result of the light spot. The image formed by the light reflected from the upper surface of the film;

The processing unit is specifically used for:

According to the first image and the second image, the thickness of the sticker is determined.
The device according to claim 2, wherein the processing unit is specifically configured to:

The thickness of the sticker film is determined according to the difference between the radial length of the first image and the second image.
3. The device according to claim 3, wherein the greater the difference between the radial length of the first image and the second image, the greater the thickness of the sticker.
The device according to any one of claims 2 to 4, wherein the excitation light source is a light-emitting layer of the display screen, and the light spot is located in a fingerprint collection area in the display screen.
The device according to any one of claims 2 to 5, wherein the device further comprises a lens, and the lens is located between the display screen and the optical fingerprint sensor, and is used to divide the light spot The direct light and the light reflected by the upper surface of the film are imaged to the optical fingerprint sensor.
The device according to any one of claims 2 to 6, wherein the specific shape is a circle, ellipse, triangle, rectangle, or polygonal ring.
The device according to any one of claims 2 to 7, wherein the light spot is a monochromatic light spot or a composite color light spot.
The device according to any one of claims 2 to 8, wherein the light spot is a bright light spot on a dark background, or a dark light spot on a bright background.
The device according to any one of claims 1 to 9, wherein the processing unit is specifically configured to:

Determining the film thickness range of the film thickness;

Among the candidate fingerprint algorithms, the fingerprint algorithm corresponding to the film thickness range is selected.
A fingerprint recognition method, characterized in that the method includes:

Obtain the thickness of the film on the display screen;

The fingerprint algorithm is determined according to the thickness of the sticker, and the fingerprint algorithm is used for fingerprint identification.
The method according to claim 11, wherein said obtaining the thickness of the film on the display screen comprises:

Collect a first image and a second image of a light spot with a specific shape emitted by an excitation light source for fingerprint recognition, where the first image is an image formed by the direct light of the light spot, and the second image is the result of the light spot. The image formed by the light reflected from the upper surface of the film;

According to the first image and the second image, the thickness of the sticker is determined.
The method according to claim 12, wherein the determining the thickness of the sticker film according to the first image and the second image comprises:

The thickness of the sticker film is determined according to the difference between the radial length of the first image and the second image.
The method of claim 13, wherein the greater the difference between the radial length of the first image and the second image, the smaller the thickness of the sticker.
The method according to any one of claims 12 to 14, wherein the specific shape is a circle, ellipse, triangle, rectangle, or polygonal ring.
The method according to any one of claims 12 to 15, wherein the light spot is a monochromatic light spot or a composite color light spot.
The method according to any one of claims 12 to 16, wherein the light spot is a bright light spot under a dark background, or a dark light spot under a bright background.
The method according to any one of claims 11 to 17, wherein the determining a fingerprint algorithm according to the thickness of the sticker includes:

Determining the film thickness range of the film thickness;

Among the candidate fingerprint algorithms, the fingerprint algorithm corresponding to the film thickness range is selected.
An electronic device, characterized in that, the electronic device includes:

Display screen

Optical fingerprint sensor; and,

The fingerprint identification device according to any one of claims 1 to 10.