Fingerprint module, fingerprint image acquisition method, electronic equipment and storage medium

Abstract

The invention provides a fingerprint module, a fingerprint image acquisition method, electronic equipment and a storage medium, and relates to the technical field of fingerprint acquisition. In order to solve the problem of low fingerprint acquisition quality, the invention provides a fingerprint module which is arranged below a display screen and comprises an infrared light source and an image sensor, and the surface of a finger in contact with the display screen reflects light emitted by the infrared light source to generate first reflected light; the lower surface and / or the interior of the display screen reflect the light emitted by the infrared light source to generate second reflected light; the image sensor performs fingerprint image acquisition by using the first reflected light, and the duration of the infrared light source in the lightening state is less than the first target duration, so that a first moment when the first reflected light starts to enter the image sensor is later than a second moment when the second reflected light stops entering the image sensor. Therefore, the interference of light emission of the display module on the camera is avoided, the fingerprint acquisition quality is improved, and optimization of fingerprint imaging is realized.

Description

Technical Field

[0001] This invention relates to the field of fingerprint acquisition technology, and in particular to a fingerprint module, a fingerprint image acquisition method, an electronic device, and a storage medium. Background Technology

[0002] Under-display optical fingerprint technology mainly utilizes the transmittance of OLED (Organic Light-Emitting Diode) to allow the reflected light from the fingerprint to pass through the OLED to reach the camera, thereby collecting the fingerprint image and realizing the fingerprint recognition function based on the fingerprint image.

[0003] In current under-display optical fingerprint collection methods, the camera is located below the OLED screen. The OLED emits visible light, which is reflected off the finger's surface and onto the camera to generate a fingerprint image. However, the quality of the fingerprint images collected by this method is not high. Summary of the Invention

[0004] The present invention provides a fingerprint module, a fingerprint image acquisition method, an electronic device, and a storage medium to overcome or at least partially solve the above-mentioned problems.

[0005] The first aspect of the present invention provides a fingerprint module for being disposed below a display screen; the fingerprint module includes: an infrared light source and an image sensor;

[0006] The surface of a finger touching the display screen reflects the light emitted by the infrared light source, generating a first reflected light;

[0007] The lower surface and / or interior of the display screen reflect the light emitted by the infrared light source to generate a second reflected light;

[0008] The image sensor uses the first reflected light to acquire fingerprint images;

[0009] Wherein, the duration for which the infrared light source is in the lit state is less than the duration of the first target, so that the first moment when the first reflected light begins to enter the image sensor is later than the second moment when the second reflected light stops entering the image sensor.

[0010] A second aspect of the present invention provides an electronic device, comprising:

[0011] Display screen;

[0012] The fingerprint module as described in the first aspect of the present invention is disposed below the display screen.

[0013] A third aspect of the present invention provides a fingerprint image acquisition method applied to a fingerprint module, the fingerprint module being disposed below a display screen; the fingerprint module includes: an infrared light source and an image sensor; the method includes:

[0014] The duration for which the infrared light source is kept lit is less than the duration of the first target, so that the first moment when the first reflected light begins to enter the image sensor is later than the second moment when the second reflected light stops entering the image sensor.

[0015] The image sensor is controlled to acquire a fingerprint image using the first reflected light.

[0016] The first reflected light is generated by the reflection of light emitted by the infrared light source by the surface of a finger touching the display screen, and the second reflected light is generated by the reflection of light emitted by the infrared light source by the lower surface and / or interior of the display screen.

[0017] A fourth aspect of the present invention provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executed, implements the steps of the fingerprint image acquisition method described in the third aspect of the present invention.

[0018] The fifth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the fingerprint image acquisition method described in the third aspect of the present invention.

[0019] The fingerprint module provided by this invention includes an infrared light source and an image sensor. When the infrared light source is lit, it emits infrared light. The surface of the finger touching the display screen reflects the light emitted by the infrared light source, generating first reflected light. The image sensor uses the first reflected light to acquire a fingerprint image. The lower surface and / or interior of the display screen also reflect the light emitted by the infrared light source, generating second reflected light. The infrared light source of this invention can emit light for a single, short duration, meaning its lit duration is less than the first target duration. This ensures that the first moment the first reflected light begins to enter the image sensor is later than the second moment the second reflected light stops entering the image sensor, guaranteeing that the times of the first and second reflected light entering the image sensor do not overlap. Therefore, when the image sensor uses the first reflected light to acquire a fingerprint image, it can ensure that the fingerprint image acquisition is not interfered with by other reflected light, allowing for a longer exposure time and preventing camera saturation, thereby improving fingerprint acquisition quality and optimizing fingerprint imaging. Furthermore, this invention uses an infrared light source to emit infrared light for fingerprint image acquisition. Infrared light has stronger penetrability than visible light, making it easier for infrared light to penetrate low-transmittance displays and reach the finger surface for fingerprint acquisition. This avoids the situation where the light signal intensity reflected to the image sensor is insufficient due to the low transmittance of the display, thus achieving fingerprint imaging optimization for low-transmittance displays. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an under-display optical fingerprint acquisition method proposed in related technologies;

[0022] Figure 2 This is a structural block diagram of a fingerprint module shown in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram illustrating an under-display optical fingerprint acquisition method according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of a CIS pixel circuit structure according to an embodiment of the present invention;

[0025] Figure 5 This is a timing diagram illustrating a fingerprint image acquisition operation according to an embodiment of the present invention;

[0026] Figure 6This is a schematic diagram of a CIS pixel circuit structure shown in another embodiment of the present invention;

[0027] Figure 7 This is a structural block diagram of an electronic device provided in an embodiment of the present invention;

[0028] Figure 8 This is a flowchart of the steps of a fingerprint image acquisition method provided in an embodiment of the present invention;

[0029] Figure 9 This is a schematic diagram of an electronic device according to another embodiment of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Biometric technology has been widely applied to various terminal devices and electronic devices. Biometric identification technologies include, but are not limited to, fingerprint recognition, palm print recognition, vein recognition, iris recognition, facial recognition, liveness detection, and anti-counterfeiting technologies. Taking fingerprint recognition technology as an example, it includes fingerprint image acquisition technology, which can be applied to portable or mobile terminals such as smartphones, tablets, and gaming devices, as well as other electronic devices such as smart locks, automobiles, and bank ATMs. The fingerprint image acquisition described in this embodiment of the invention is optical fingerprint image acquisition.

[0032] This invention takes into account the interference problem caused by OLED reflected light generated by current under-display optical fingerprint collection methods: Figure 1 This is a schematic diagram of an under-display optical fingerprint acquisition method proposed in related technologies, such as... Figure 1 As shown, the camera is located below the OLED screen. The OLED emits visible light, which is reflected off the finger's surface and onto the camera to create a fingerprint image. However, because the light emitted by the OLED is directly projected onto the camera, this light does not contain fingerprint information and can interfere with the camera, causing it to easily become saturated (overexposed). This prevents the camera from capturing a high-quality fingerprint image by extending the exposure time.

[0033] Based on this, the present invention proposes a fingerprint module, including an infrared light source and an image sensor. When the infrared light source is lit, it emits infrared light. The surface of the finger touching the display screen reflects the light emitted by the infrared light source, generating first reflected light. The image sensor uses the first reflected light to acquire a fingerprint image. The present invention ensures that the infrared light source emits light for a short duration (less than the first target duration), so that the first reflected light begins to enter the image sensor at a time later than the second reflected light stops entering the image sensor. This guarantees that the times of the first and second reflected light entering the image sensor do not overlap. Therefore, when the image sensor uses the first reflected light to acquire a fingerprint image, it can ensure that the fingerprint image acquisition is not interfered with by other reflected light, allowing for a longer exposure time without camera saturation, thereby improving fingerprint acquisition quality and optimizing fingerprint imaging.

[0034] Reference Figure 2 The diagram illustrates a structural block diagram of a fingerprint module according to an embodiment of the present invention. The fingerprint module provided in the first aspect of the present invention includes at least an infrared light source and an image sensor, and the fingerprint module is disposed below the display screen. The image sensor has the ability to sense light emitted by the infrared light source. In an optional embodiment, the fingerprint module can be disposed in a partial or complete area below the display screen, thereby forming an under-display optical fingerprint acquisition system.

[0035] When fingerprint collection is triggered, the infrared light source illuminates and emits infrared light. This infrared light reaches the display screen, where a portion undergoes a first reflection: the lower surface and / or interior of the display screen reflects the light emitted by the infrared light source, generating a second reflected light. This first reflection is caused by the metal on the lower surface and / or interior of the display screen. The second reflected light can enter the image sensor, and since it does not carry fingerprint information, it is considered interference and needs to be removed.

[0036] Another portion of the infrared light passes through the display screen and reaches the surface of the finger touching the screen, where it undergoes a second reflection, forming the first reflected light: the surface of the finger touching the screen reflects the light emitted by the infrared light source, generating the first reflected light. The first reflected light carries the fingerprint information of the finger surface, and the first reflected light carrying the fingerprint information can pass through the display screen to reach the image sensor. The image sensor receives the first reflected light and uses the first reflected light to acquire a fingerprint image.

[0037] This embodiment addresses the aforementioned technical shortcomings by analyzing that the display screen cannot emit light for short periods, causing the visible light emitted by the display screen to overlap with the light directly reflected from the finger surface, resulting in unavoidable interference. Therefore, this embodiment incorporates an infrared light source, with the duration of its illumination being less than a first target duration. This ensures that the first moment the first reflected light begins to enter the image sensor is later than the second moment the second reflected light stops entering the image sensor. Thus, this embodiment can ensure that the times when the first and second reflected light enter the image sensor do not overlap by controlling the infrared light source to emit light for a short period (i.e., the duration of its illumination is less than the first target duration). In an optional embodiment, the image sensor can control the duration of the infrared light source's illumination to be less than the first target duration, or a controller in the electronic device (such as the CPU in a mobile phone or tablet) can control the duration of the infrared light source's illumination to be less than the first target duration, etc. This embodiment does not impose specific limitations on this.

[0038] In an alternative embodiment, the image sensor may be a CIS (CMOS Image Sensor).

[0039] In this embodiment, the infrared light source can emit light for a short, single burst, meaning its illuminated duration is shorter than the first target duration. This ensures that the first moment the first reflected light begins to enter the image sensor is later than the second moment the second reflected light stops entering the image sensor, guaranteeing that the arrival times of the first and second reflected light do not overlap. Thus, when the image sensor uses the first reflected light to acquire a fingerprint image, it is ensured that the fingerprint image acquisition is not interfered with by other reflected light, allowing for a longer exposure time and preventing camera saturation. This improves fingerprint acquisition quality and optimizes fingerprint imaging. Furthermore, this invention uses an infrared light source to emit infrared light for fingerprint image acquisition. Infrared light has stronger penetrating power than visible light, making it easier to penetrate low-transmittance displays and reach the finger surface for fingerprint acquisition. This avoids insufficient light signal intensity reflected to the image sensor due to low display transmittance, thus optimizing fingerprint imaging on low-transmittance displays.

[0040] In one alternative embodiment, the image sensor does not have the ability to sense visible light. During fingerprint image acquisition, the display screen may or may not emit light. When the display screen emits light (emitting visible light), the visible light reflected after passing through the finger surface, as well as the visible light directly reflected by the display screen, will not be sensed by the image sensor even if they are projected onto it. Therefore, interference from the display screen emitting light to the image sensor is avoided.

[0041] In conjunction with the above embodiments, in one embodiment, the display screen includes at least a backlight and a glass cover, the glass cover is attached to the backlight and is positioned above the backlight, the surface of a finger contacts the glass cover, and the backlight has holes.

[0042] In this embodiment, when fingerprint acquisition is triggered, an infrared light source emits infrared light. The infrared light first reaches the light-emitting backplate, passes through the holes in the light-emitting backplate, passes through the glass cover, and reaches the surface of the finger, forming a reflection to generate first reflected light. The first reflected light then passes through the glass cover, through the holes in the light-emitting backplate, and reaches the image sensor. The image sensor receives the first reflected light and uses it to acquire a fingerprint image.

[0043] In an alternative embodiment, the backlight can be an OLED or a liquid crystal display (LCD), etc., and there is no limitation thereto.

[0044] In this embodiment, by creating holes in the light-emitting backplate, infrared light can reach the finger surface smoothly to collect fingerprint images without being interfered with by the low transmittance of the light-emitting backplate, thereby further improving the fingerprint collection quality.

[0045] In conjunction with the above embodiments, in one embodiment, the first aspect of the present invention also provides a fingerprint module. In this embodiment, the infrared light source can be periodically illuminated multiple times, and the image sensor can acquire fingerprint images based on the first reflected light generated by the multiple illuminations. The first reflected light generated by the multiple illuminations carries more fingerprint information, enabling the image sensor to acquire higher quality fingerprint images, further improving fingerprint acquisition quality and optimizing fingerprint imaging.

[0046] In this embodiment, the time interval between the first and next illumination of the infrared light source is greater than the second target duration, so that the third moment when the first reflected light generated by the infrared light source stops entering the image sensor is earlier than the fourth moment when the second reflected light generated by the infrared light source starts entering the image sensor. This ensures that the time when the first and second reflected light generated by the infrared light source illuminates the image sensor does not overlap, further ensuring that the image sensor is not interfered with by other reflected light (such as the second reflected light) when acquiring fingerprint images.

[0047] Because the infrared light source is periodically lit multiple times, each lighting cycle generates a corresponding first reflected light and a second reflected light. However, for each lighting cycle of the infrared light source, the first reflected light enters the image sensor later than the second reflected light. Based on this, this embodiment controls the time interval between the periodic lighting of the infrared light source: the time interval between the current lighting cycle and the next lighting cycle is controlled to be greater than the second target duration, ensuring that the time of the first reflected light generated during the current lighting cycle and the second reflected light generated during the next lighting cycle do not overlap when they enter the image sensor.

[0048] In one optional embodiment, the time interval between the current illumination and the next illumination of the infrared light source may be greater than the second target duration, controlled by an image sensor. Alternatively, the controller in an electronic device (such as the CPU in a mobile phone or tablet) may control the time interval between the current illumination and the next illumination of the infrared light source to be greater than the second target duration, etc. This embodiment does not impose specific limitations on this.

[0049] In one embodiment, such as Figure 3 As shown, Figure 3 This is a schematic diagram illustrating an under-display optical fingerprint sensor according to an embodiment of the present invention. In this embodiment, the infrared camera includes an image sensor and an optical lens above the image sensor. Figure 3 In this fingerprint module, an infrared light source (IRlight) and an infrared camera are used. The display includes a cover glass and a backlight (such as OLED). The infrared light source illuminates and emits infrared light. When this light reaches the backlight, a portion undergoes a first reflection, generating a second reflected light. This second reflection, caused by the metal back of the backlight, contains no fingerprint information and is considered interference, needing to be removed. Next, another portion of the infrared light passes through holes in the backlight, through the glass cover, and reaches the finger surface, forming a second reflection and generating a first reflected light. This first reflected light carries fingerprint information and passes through the holes in the backlight to the infrared camera, which uses the first reflected light to capture the fingerprint image. In this embodiment, the duration of the infrared light source being lit is less than the duration of the first target, so that the first moment when the first reflected light begins to enter the infrared camera is later than the second moment when the second reflected light stops entering the infrared camera. This ensures that the times when the first and second reflected light enter the infrared camera do not overlap. In this way, when the infrared camera uses the first reflected light to collect fingerprint images, it can ensure that the infrared camera is not interfered with by other reflected light when collecting fingerprint images.

[0050] In conjunction with any of the above embodiments, in one embodiment, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the infrared light source is periodically illuminated multiple times; corresponding to each illumination of the infrared light source, the image sensor performs one exposure, and each exposure of the image sensor corresponds to an exposure start time and an exposure end time.

[0051] In this embodiment, the exposure start time of the image sensor is no earlier than the first moment when the first reflected light begins to enter the image sensor; the exposure end time of the image sensor is no later than the third moment when the first reflected light stops entering the image sensor. Thus, this embodiment ensures that the image sensor performs exposure to acquire fingerprint images only during the period when the first reflected light enters the image sensor, ensuring that the image sensor is not interfered with by other reflected light (such as second reflected light) when acquiring fingerprint images.

[0052] In conjunction with any of the above embodiments, in one embodiment, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the image sensor includes at least: a photosensitive unit, a first switch, and a storage unit; and the first switch is disposed between the photosensitive unit and the storage unit.

[0053] In this embodiment, after the first reflected light reaches the image sensor, it can reach the photosensitive unit. The photosensitive unit can generate a signal charge based on the received first reflected light. This signal charge carries fingerprint information and is used to generate a first fingerprint signal. In an optional embodiment, the photosensitive unit mainly consists of a photodiode structure, which can form a signal charge after receiving light.

[0054] In this embodiment, the first switch is closed during the exposure time of the image sensor, ensuring that the photosensitive unit maintains a communication connection with the storage unit during this period. Conversely, the first switch is open for the remaining time period outside the image sensor's exposure time, preventing the photosensitive unit from maintaining a communication connection with the storage unit during this time. The exposure time period in this embodiment is the time between the start and end of the exposure.

[0055] In this embodiment, during the period when the first switch is in the closed state, the photosensitive unit can temporarily store the generated signal charge in the storage unit (generally a capacitor structure for temporary storage) through the first switch. The photosensitive unit generates a signal charge upon receiving light and temporarily stores the signal charge in the storage unit; this constitutes one exposure process.

[0056] In this embodiment, the first switch is closed during the exposure time of the image sensor and open during the remaining time outside the exposure time. This allows for precise control of the exposure timing of the image sensor, enabling the exposure to be activated synchronously after the first reflected light containing fingerprint information reaches the image sensor. Only the first reflected light reflected from the finger surface is processed to generate signal charges, avoiding interference from other reflected light and improving the acquisition quality of the fingerprint image.

[0057] In conjunction with any of the above embodiments, in one embodiment, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the image sensor further includes: a second switch and a charge integration unit, wherein the second switch is disposed between the storage unit and the charge integration unit.

[0058] In this embodiment, the second switch is in the closed state for the period from the end of the current exposure of the image sensor to the start of the next exposure of the image sensor. The second switch is in the open state for the remaining time outside the closed state period.

[0059] During the period when the second switch is closed, the storage unit can store the current temporary signal charge to the charge integration unit through the second switch. The charge integration unit can accumulate the signal charge received multiple times. The total amount of signal charge accumulated by the charge integration unit multiple times is used to generate a second fingerprint signal, which is greater than the first fingerprint signal.

[0060] In this embodiment, multiple exposures are performed, and the signal charges generated from these exposures are accumulated to form a high fingerprint signal quantity, which is essential for better fingerprint acquisition. Based on this, a charge integration unit is set after the storage unit. After each exposure, the signal charges temporarily stored in the storage unit are placed into the charge integration unit. The signal charges generated from multiple exposures accumulate in the charge integration unit to form a high signal quantity, which is then used for fingerprint image generation. Thus, this embodiment can optimize fingerprint imaging on low-transmittance displays by using an active light emission mode and a fast shutter speed, solving the interference problem of reflected light from the display screen. Furthermore, even with low transmittance displays, the exposure time can be increased without saturation.

[0061] In one embodiment, the image sensor is a CIS (CMOS image sensor), which includes at least: a photosensitive unit, a first switch, a memory unit, a second switch, and a charge integration unit. Figure 4 As shown, Figure 4 This is a schematic diagram illustrating a CIS pixel circuit structure according to an embodiment of the present invention. Figure 4In CIS, there are three basic units: photosensitive unit, storage unit and charge integration unit. The photosensitive unit is mainly composed of a photodiode structure. After being exposed to light, it forms a signal charge, which is the exposure process. The signal charge is injected into the storage unit through the first switch (S1), which is usually a capacitor structure for temporary storage. Then it enters the charge integration unit through the second switch (S2). The charge integration unit will accumulate the signal charge from multiple exposures.

[0062] In one embodiment, the display screen includes at least an OLED, the first switch is S1, and the second switch is S2. Figure 5 As shown, Figure 5 This is a timing diagram illustrating a fingerprint image acquisition operation according to an embodiment of the present invention. Figure 5 In this embodiment, the timing signal within the image sensor can be used for control as follows: After the infrared light source (IRlight) emits light, the infrared light first reaches the OLED and is reflected. This reflected light (i.e., the second reflected light) does not contain fingerprint information, causing interference. Therefore, the image sensor's exposure has not started at this time (i.e., Camera exposure S1 is at a low level, representing S1 being disconnected, and the storage unit is disconnected from the photosensitive unit). Subsequently, the infrared light reaches the finger surface and is reflected. This reflected light (i.e., the first reflected light) contains fingerprint information. After reaching the camera (the infrared camera, which includes an image sensor and an optical lens above the image sensor), the exposure is synchronously turned on (i.e., Camera exposure S1 is at a high level, representing S1 being closed, and the storage unit is connected to the photosensitive unit). In this way, only the light reflected from the finger is received, while the light reflected from the OLED back panel is not captured by the camera (i.e., the second reflected light from the OLED does not start exposure after reaching the camera), thus eliminating interference. In this embodiment, the camera's exposure is equivalent to the image sensor's exposure. In this embodiment, it is ensured that the first reflected light from the finger reaches the image sensor and the exposure is synchronously turned on.

[0063] Furthermore, during the period from the closing of the current Camera exposure S1 to the closing of the next Camera exposure S1, or during the entire period from the closing of the current Camera exposure S1 to the closing of the next Camera exposure S1, the second switch is controlled to close (i.e., the charge integration S2 is at a high level), and before the closing of the next Camera exposure S1, the second switch is controlled to open (i.e., the charge integration S2 is at a low level), thereby completing the control of signal charge accumulation.

[0064] In conjunction with any of the above embodiments, in one implementation, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the image sensor further includes a controller. The controller is electrically connected to at least one of a first switch and a second switch.

[0065] If the controller is electrically connected to the first switch, the controller controls the first switch to be in a closed state during the exposure time of the image sensor and in an open state during the remaining time period excluding the exposure time.

[0066] If the controller is electrically connected to the second switch, the controller controls the second switch such that the second switch is in the closed state for the period of time between the end of the current exposure of the image sensor and the start of the next exposure of the image sensor; and the second switch is in the open state for the remaining period outside the closed state. Furthermore, in other embodiments, the controller can be a main control unit of the electronic device, such as a CPU.

[0067] In conjunction with any of the above embodiments, in one implementation, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the image sensor further includes a charge detection unit.

[0068] In this embodiment, the charge detection unit is communicatively connected to both the photosensitive unit and the charge integration unit. The charge detection unit can detect the total amount of signal charge accumulated multiple times by the charge integration unit, and determine whether the total amount of signal charge accumulated multiple times by the charge integration unit reaches the target charge amount. The target charge amount represents the minimum charge amount sufficient to generate a fingerprint image. The target charge amount can be freely set according to the fingerprint generation requirements, and its specific value is not limited.

[0069] If the total amount of signal charge accumulated by the charge integration unit (the total amount of signal charge stored in the charge integration unit during a single fingerprint acquisition process) does not reach the target charge amount, it indicates that the currently obtained fingerprint signal is insufficient to generate a fingerprint image. At this time, the charge detection unit instructs the photosensitive unit to continue generating signal charge until the total amount of signal charge accumulated by the charge integration unit reaches the target charge amount.

[0070] When the total amount of signal charge accumulated by the charge integration unit reaches the target charge amount, it indicates that the currently acquired fingerprint signal is sufficient to generate a fingerprint image. At this point, the charge detection unit instructs the photosensitive unit to stop generating signal charge, thereby completing one fingerprint acquisition.

[0071] In addition, in an alternative embodiment, the exposure can be controlled by setting the number of accumulations in the charge integration unit. Adaptive exposure can be achieved by adjusting the number of integrations (accumulations). When the charge detection unit determines that the number of accumulations in the charge integration unit has reached the target number, it instructs the photosensitive unit to stop generating signal charges and / or completely turn off the exposure (e.g., in one embodiment, the charge detection unit instructs the controller to completely disconnect the first switch during this fingerprint acquisition).

[0072] In an alternative embodiment, exposure is completely shut off when the total amount of signal charge accumulated by the charge integration unit reaches the target charge amount (e.g., in one embodiment, the charge detection unit instructs the controller to completely disconnect the first switch during this fingerprint acquisition).

[0073] In conjunction with any of the above embodiments, in one embodiment, the first aspect of the present invention further provides a fingerprint module. In this embodiment, the image sensor further includes: a charge detection unit and an analog-to-digital conversion unit.

[0074] In this embodiment, the charge detection unit is communicatively connected to both the photosensitive unit and the charge integration unit, and the analog-to-digital conversion unit is communicatively connected to both the charge detection unit and the charge integration unit. The charge detection unit can detect the total amount of signal charge accumulated multiple times by the charge integration unit, and detect whether the total amount of signal charge accumulated multiple times by the charge integration unit reaches the target charge amount. The target charge amount represents the minimum charge amount sufficient to generate a fingerprint image, and the target charge amount can be freely set according to the fingerprint generation requirements; its specific value is not limited.

[0075] When the total amount of signal charge accumulated by the charge integration unit (the total amount of signal charge stored in the charge integration unit during a single fingerprint acquisition process) reaches the target charge amount, it indicates that the currently obtained fingerprint signal is sufficient to generate a fingerprint image. At this time, the charge detection unit instructs the charge integration unit to transmit the accumulated signal charge to the analog-to-digital conversion unit. The analog-to-digital conversion unit can perform analog-to-digital conversion based on the received signal charge to obtain the fingerprint image.

[0076] In one embodiment, the image sensor is a CIS (CMOS image sensor), which includes at least: a photosensitive unit, a first switch, a storage unit, a second switch, a charge integration unit, a charge detection unit, and an analog-to-digital conversion unit. Figure 6 As shown, Figure 6 This is a schematic diagram illustrating a CIS pixel circuit structure according to another embodiment of the present invention. Figure 6 In CIS, there are five basic units: photosensitive unit, storage unit, charge integration unit, charge detection unit, and analog-to-digital conversion unit (ADC unit). Figure 6The photosensitive unit, first switch, storage unit, second switch, and charge integration unit in the middle are... Figure 4 The photosensitive unit, first switch, storage unit, second switch, and charge integration unit are the same or similar. When the total amount of signal charge accumulated in the charge integration unit reaches the target charge amount, the exposure is completely turned off. The charge detection unit instructs the charge integration unit to transfer the accumulated signal charge to the subsequent analog-to-digital conversion unit and requests the analog-to-digital conversion unit to quantize the accumulated signal charge to perform analog-to-digital conversion to obtain a fingerprint image. The analog-to-digital conversion unit then outputs the fingerprint image to the host (such as the main processor of an electronic device).

[0077] Based on the same inventive concept, a second aspect of the present invention provides an electronic device. (See reference...) Figure 7 , Figure 7 This is a structural block diagram of an electronic device provided in an embodiment of the present invention. The electronic device includes: a display screen, and a fingerprint module provided in the first aspect of the present invention, the fingerprint module being disposed below the display screen.

[0078] Based on the same inventive concept, a third aspect of this invention provides a fingerprint image acquisition method, which is applied to a fingerprint module, the fingerprint module comprising: an infrared light source and an image sensor. (Reference) Figure 8 , Figure 8 This is a flowchart illustrating the steps of a fingerprint image acquisition method provided in an embodiment of the present invention. The method includes:

[0079] S101, control the duration of the infrared light source being lit to be less than the first target duration, so that the first moment when the first reflected light begins to enter the image sensor is later than the second moment when the second reflected light stops entering the image sensor.

[0080] S102, control the image sensor to acquire fingerprint image using the first reflected light.

[0081] The first reflected light is generated by the reflection of light emitted by the infrared light source by the surface of a finger touching the display screen, and the second reflected light is generated by the reflection of light emitted by the infrared light source by the lower surface and / or interior of the display screen.

[0082] Optionally, the time interval between the current illumination and the next illumination of the infrared light source is greater than the second target duration, so that the third moment when the first reflected light generated by the current illumination of the infrared light source stops entering the image sensor is earlier than the fourth moment when the second reflected light generated by the next illumination of the infrared light source begins to enter the image sensor.

[0083] Optionally, the infrared light source is periodically lit, and the image sensor performs one exposure corresponding to each lighting of the infrared light source;

[0084] The exposure start time of the image sensor is no earlier than the first moment when the first reflected light begins to enter the image sensor;

[0085] The exposure end time of the image sensor is no later than the third moment when the first reflected light stops entering the image sensor.

[0086] Optionally, step S102 above includes at least:

[0087] The photosensitive unit in the image sensor generates a signal charge based on the received first reflected light;

[0088] During the exposure time period of the image sensor, the photosensitive unit temporarily stores the signal charge in the storage unit of the image sensor, and the signal charge is used to generate a first fingerprint signal; the exposure time period is the time period between the start time of the exposure and the end time of the exposure.

[0089] Optionally, the above S102 further includes:

[0090] The storage unit stores the temporarily stored signal charge in the charge integration unit of the image sensor during the time period between the end of the current exposure of the image sensor and the start of the next exposure of the image sensor. The total amount of signal charge accumulated by the charge integration unit is used to generate a second fingerprint signal, which is greater than the first fingerprint signal.

[0091] Optionally, the above S102 further includes:

[0092] The charge detection unit detects whether the total amount of signal charge accumulated multiple times by the charge integration unit in the image sensor reaches the target charge amount.

[0093] If the total amount of signal charge accumulated by the multiple accumulations does not reach the target charge amount, the charge detection unit instructs the photosensitive unit to continue generating signal charge until the total amount of signal charge accumulated by the charge integration unit reaches the target charge amount.

[0094] When the total amount of accumulated signal charge reaches the target charge amount, the charge detection unit instructs the photosensitive unit to stop generating signal charge.

[0095] Optionally, the above S102 further includes:

[0096] The charge detection unit detects whether the total amount of signal charge accumulated multiple times by the charge integration unit in the image sensor reaches the target charge amount.

[0097] When the total amount of the accumulated signal charge reaches the target charge amount, the charge detection unit instructs the charge integration unit to transfer the accumulated signal charge to the analog-to-digital conversion unit in the image sensor.

[0098] The analog-to-digital conversion unit performs analog-to-digital conversion based on the received signal charge to obtain a fingerprint image.

[0099] As the method embodiments are basically similar to the fingerprint module embodiments, the description is relatively simple. For relevant details, please refer to the description of the fingerprint module embodiments.

[0100] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of the present invention are not limited to the described order of actions, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0101] Based on the same inventive concept, a fourth aspect of the present invention provides an electronic device, such as... Figure 9 As shown. Figure 9 This is a schematic diagram of an electronic device according to another embodiment of the present invention. The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the fingerprint image acquisition method described in the third aspect of the present invention.

[0102] Based on the same inventive concept, a fifth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the fingerprint image acquisition method described in the third aspect of the present invention.

[0103] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0104] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, embodiments of the present invention can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of the present invention can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] The embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable image processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable image processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0106] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable image processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable image processing terminal device, causing a series of operational steps to be performed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal device for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0108] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0109] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0110] The fingerprint module, fingerprint image acquisition method, electronic device, and storage medium provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fingerprint module, characterized in that, The fingerprint module is arranged below the display screen; the fingerprint module comprises an infrared light source and an image sensor; A finger surface contacting the display screen reflects the light emitted by the infrared light source to generate first reflected light; The lower surface and / or the interior of the display screen reflects the light emitted by the infrared light source to generate second reflected light; The image sensor collects a fingerprint image by using the first reflected light; The duration of the infrared light source in the lighting state is less than a first target duration, so that the first time when the first reflected light begins to enter the image sensor is later than the second time when the second reflected light stops entering the image sensor.

2. The fingerprint module of claim 1, wherein, The time interval between the current lighting of the infrared light source and the next lighting is greater than a second target duration, so that the third time when the first reflected light generated by the current lighting of the infrared light source stops entering the image sensor is earlier than the fourth time when the second reflected light generated by the next lighting of the infrared light source begins to enter the image sensor.

3. The fingerprint module according to claim 1 or 2, characterized in that, The infrared light source is periodically lit, and the image sensor is exposed once corresponding to one lighting of the infrared light source; The exposure start time of the image sensor is not earlier than the first time when the first reflected light begins to enter the image sensor, and the exposure end time of the image sensor is not later than the third time when the first reflected light stops entering the image sensor.

4. The fingerprint module of claim 3, wherein, The image sensor at least comprises a photosensitive unit, a first switch and a storage unit, and the first switch is arranged between the photosensitive unit and the storage unit; The photosensitive unit generates signal charges based on the received first reflected light; The first switch is in a closed state during an exposure time period of the image sensor, and is in an open state during a remaining time period except the exposure time period, and the exposure time period is a time period between the exposure start time and the exposure end time. The photosensitive unit temporarily stores the signal charges to the storage unit during the closed state of the first switch, and the signal charges are used to generate a first fingerprint signal amount.

5. The fingerprint module of claim 4, wherein, The image sensor further comprises a second switch and a charge integration unit, and the second switch is arranged between the storage unit and the charge integration unit; The time period during which the second switch is in a closed state is a time period between the exposure end time of the current exposure of the image sensor and the exposure start time of the next exposure of the image sensor; The storage unit stores the current temporarily stored signal charges to the charge integration unit during the time period during which the second switch is in a closed state, and the total amount of the signal charges accumulated by the charge integration unit multiple times is used to generate a second fingerprint signal amount, and the second fingerprint signal amount is greater than the first fingerprint signal amount.

6. The fingerprint module of claim 5, wherein, The image sensor further comprises a controller, and the controller is electrically connected with at least one of the first switch and the second switch.

7. The fingerprint module of claim 5, wherein the first and second substrates are made of glass. The image sensor further comprises a charge detection unit; The charge detection unit detects whether the total amount of the signal charges accumulated by the charge integration unit multiple times reaches a target charge amount. In a case where the total amount of the multiple accumulated signal charges does not reach the target charge amount, the charge detection unit instructs the photosensitive unit to continue to generate signal charges until the total amount of the multiple accumulated signal charges reaches the target charge amount. In a case where the total amount of the multiple accumulated signal charges reaches the target charge amount, the charge detection unit instructs the photosensitive unit to stop generating signal charges.

8. The fingerprint module of claim 5, wherein, The image sensor further comprises a charge detection unit and an analog-digital conversion unit. The charge detection unit detects whether the total amount of the multiple accumulated signal charges reaches a target charge amount. In a case where the total amount of the multiple accumulated signal charges reaches the target charge amount, the charge detection unit instructs the charge accumulation unit to transmit the multiple accumulated signal charges to the analog-digital conversion unit. The analog-digital conversion unit performs analog-digital conversion based on the received signal charges to obtain a fingerprint image.

9. An electronic device, comprising: The fingerprint module comprises: a display screen; The fingerprint module according to any one of claims 1-8 is arranged below the display screen.

10. A method of capturing a fingerprint image, characterized by, The fingerprint module is arranged below the display screen. The fingerprint module comprises an infrared light source and an image sensor; and the method comprises: controlling the infrared light source to be in a lighting state for a duration less than a first target duration, so that a first time at which first reflected light starts to enter the image sensor is later than a second time at which second reflected light stops entering the image sensor; controlling the image sensor to collect a fingerprint image by using the first reflected light; The first reflected light is generated by the surface of a finger contacting the display screen reflecting light emitted by the infrared light source, and the second reflected light is generated by the lower surface and / or the interior of the display screen reflecting light emitted by the infrared light source.

11. An electronic device, comprising: A computer program product comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the fingerprint image collection method of claim 10 when executed.

12. A computer-readable storage medium, characterized in that, A computer program product comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the fingerprint image collection method of claim 10 when executed.

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